業績情報

• Unsaturated hydraulic properties of recycled concrete aggregates blended with autoclaved aerated concrete grains for unbound road base materials in Vietnam
  Van Nam Pham; Tien Dung Nguyen; Hoang Giang Nguyen; Ken Kawamoto
  Journal of Material Cycles and Waste Management, 巻：27, 号：2, 開始ページ：712, 終了ページ：728, 2024年12月, ［査読有り］, ［最終著者］
  Abstract
  
  Understanding of hydraulic properties is necessary to evaluate the water infiltration and balance in a road course. An easily available hydraulic model can contribute to the design of urban flooding countermeasures and mitigation of urban heat islands by covering roads with pavements. Many studies have evaluated saturated hydraulic conductivity, but few studies of measurements and modeling of unsaturated hydraulic properties such as water retention and unsaturated hydraulic conductivity for roadbase materials have been done. Therefore, this study measured the unsaturated hydraulic properties of typical roadbase materials of recycled concrete aggregates (RCA) using an evaporation method in the laboratory. To improve the water retention capacity, RCA blended with autoclaved aerated concrete (AAC) grains were also used. The results showed that the Gardner–Campbell (GC) model described the hydraulic properties of tested roadbed materials well, and the inclusion of AAC grains increased the water-holding capacity effectively. As a case study, the GC model was incorporated into the Green–Ampt infiltration model to simulate the change in the infiltration rate over time. The simulated results analyzed the water infiltration characteristics well, and this approach would be a good tool to make a quick assessment of the infiltration process of roadbed materials.
  Springer Science and Business Media LLC, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s10163-024-02134-y
  DOI ID：10.1007/s10163-024-02134-y, ISSN：1438-4957, eISSN：1611-8227, 共同研究・競争的資金等ID：44511245
• Current condition of solid waste management and JICA support in Sri Lanka　　　　　　　　　　　　　　　
  Sato, N.; T. Kondo; M.H. Cherki; M. Kalyanasundaram; K. Kawamoto
  Global Environmental Research, 巻：28, 号：4, 開始ページ：53, 終了ページ：61, 2024年12月, ［査読有り］, ［最終著者］
  英語, 研究論文（学術雑誌）
• Evaluating the thermal performance of permeable pavements: A case study in an urban Area of Vietnam　　　　　　　　　　　　　　　
  Ngo, K.T.; K. Kawamoto; M. Takata; M. Suzuki; Y. Tanaka; Q.M. Phan; H.G. Nguyen; T.D. Nguyen
  Global Environmental Research, 巻：28, 号：4, 開始ページ：45, 終了ページ：52, 2024年12月, ［査読有り］
  英語, 研究論文（学術雑誌）
• Diffusive and convective transport properties and pore-network characteristics of recycled, compacted concrete aggregates for use as road pavement materials　　　　　　　　　　　　　　　
  Hong Nam Thai; Ken Kawamoto; Hoang Giang Nguyen; Toshiko Komatsu; Per Moldrup
  Construction and Building Materials, 巻：457, 開始ページ：139460, 終了ページ：139460, 2024年12月, ［査読有り］
  Elsevier BV, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.conbuildmat.2024.139460
  DOI ID：10.1016/j.conbuildmat.2024.139460, ISSN：0950-0618, 共同研究・競争的資金等ID：44511245
• Thermal conductivity and volumetric heat capacity of air-dried granulated bentonite mixtures (GBMs) under different packing conditions　　　　　　　　　　　　　　　
  Nazir, M.; K. Nakamura; A. Matsuno; T. Sakaki; K. Kawamoto
  International Journal of GEOMATE, 巻：27, 号：122, 2024年10月, ［査読有り］, ［責任著者］
  International Journal of Geomate, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.21660/2024.122.4577
  DOI ID：10.21660/2024.122.4577, ISSN：2186-2982, eISSN：2186-2990
• Flexural behavior of reinforced concrete beams using synthetic aggregates produced from concrete waste powder in Vietnam　　　　　　　　　　　　　　　
  Tran, V.C.; N.T. Nguyen; K. Kawamoto; H.G. Nguyen
  International Journal of GEOMATE, 巻：27, 号：120, 2024年08月, ［査読有り］, ［最終著者］
  International Journal of Geomate, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.21660/2024.120.4494
  DOI ID：10.21660/2024.120.4494, ISSN：2186-2982, eISSN：2186-2990
• An empirical study of the behavior of recycled aggregate concrete beams from CDW in Hanoi, Vietnam　　　　　　　　　　　　　　　
  Nghiem, H.T.; V.T. Tran; N.T. Nguyen; Q.M. Phan; T.D. Nguyen; K. Kawamoto; H.G. Nguyen
  International Journal of GEOMATE, 巻：26, 号：118, 2024年06月, ［査読有り］
  International Journal of Geomate, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.21660/2024.118.g12300
  DOI ID：10.21660/2024.118.g12300, ISSN：2186-2982, eISSN：2186-2990, 共同研究・競争的資金等ID：44511245
• Mechanical, hydraulic, and particle breakage properties of recycled concrete aggregates blended with autoclaved aerated concrete (AAC) grains for unbound road base and subbase materials in Vietnam
  Van Nam Pham; Tien Dung Nguyen; Hoang Giang Nguyen; Ken Kawamoto
  Journal of Material Cycles and Waste Management, 巻：26, 号：2, 開始ページ：845, 終了ページ：859, 2023年12月, ［査読有り］, ［最終著者］
  Springer Science and Business Media LLC, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s10163-023-01858-7
  DOI ID：10.1007/s10163-023-01858-7, ISSN：1438-4957, eISSN：1611-8227, 共同研究・競争的資金等ID：44511245
• Compaction-induced variability in the 80/20 sand-bentonite mixture: Spatial variation in dry density at different scales in the laboratory and large-scale gas seal test　　　　　　　　　　　　　　　
  Toshihiro Sakaki; Keisuke Sakabayashi; Ken Kawamoto; Thomas Spillmann
  Applied Clay Science, 巻：246, 開始ページ：107146, 終了ページ：107146, 2023年12月, ［査読有り］
  Elsevier BV, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.clay.2023.107146
  DOI ID：10.1016/j.clay.2023.107146, ISSN：0169-1317
• Material and monetary flows of construction and demolition waste and assessment on physical and environmental properties of illegally dumped construction and demolition waste in Hanoi
  Lan Huong Nguyen; Thi Viet Nga Tran; Minh Giang Hoang; Hoang Giang Nguyen; Ton Kien Tong; Yugo Isobe; Mikio Kawasaki; Tomonori Ishigaki; Ken Kawamoto
  Environmental Science and Pollution Research, 巻：30, 号：60, 開始ページ：125965, 終了ページ：125976, 2023年11月, ［査読有り］, ［最終著者］
  Springer Science and Business Media LLC, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11356-023-30978-8
  DOI ID：10.1007/s11356-023-30978-8, eISSN：1614-7499, 共同研究・競争的資金等ID：44511245
• Autoclaved aerated concrete grains as alternative absorbent and filter media for phosphorus recovery from municipal wastewater: A case study in Hanoi, Vietnam　　　　　　　　　　　　　　　
  Hoai Son Tran; Nga Tran Thi Viet; Thu Hang Duong; Lan Huong Nguyen; Ken Kawamoto
  Environmental Technology & Innovation, 巻：31, 開始ページ：103175, 終了ページ：103175, 2023年08月, ［査読有り］, ［最終著者］
  Elsevier BV, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.eti.2023.103175
  DOI ID：10.1016/j.eti.2023.103175, ISSN：2352-1864, 共同研究・競争的資金等ID：44511245
• Mechanical properties of synthetic aggregate pelletized by waste concrete fines in Vietnam
  Tran Viet Cuong; Ken Kawamoto; Tran Thi Viet Nga; Nguyen Hoang Giang
  Journal of Science and Technology in Civil Engineering (STCE) - HUCE, 巻：17, 号：2, 開始ページ：1, 終了ページ：8, 2023年06月, ［査読有り］
  Due to rapid industrialization and economic growth, the generation of construction and demolition waste (CDW) from the activities of demolishing buildings is increasing in Vietnam. The Vietnamese Government has regulations on recycling and collecting CDW for reuse, recycling to environmental protection through Circular No. 08/2017/TT-BXD in 2017, and Directive 41/CT-TTg in 2020. Waste concrete fines (WCF) are generated during demolishing process or crushing of CDW materials. To save natural resources and increase the recycling rate, a disc pelleting technology has been used to recycle WCF. The pellet machine has a disk with 1.5m of diameter and 0.3m of depth; tilted at an angle of 55 degrees and the rotation speed from 15 to 22 rpm; the capacity is 0.5 to 0.8 tons per hour. This paper presents the results of pelletizing WCF research to produce synthetic aggregate (SA). The SA pelletized by WCF and cement had an apparent specific gravity of 2.45 – 2.55 g/cm3, a dry bulk specific gravity of 1.85 – 1.95 g/cm3, a crushing value of 19.2 – 29.9%, a LA (Los Angeles) value of 23 – 33% and water absorption around 13.2%. The mechanical properties of SA meet the requirement of TCVN 11969:2018, recycled aggregate type II for concrete.
  Hanoi University of Civil Engineering (HUCE), ベトナム語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.31814/stce.huce2023-17(2)-01
  DOI ID：10.31814/stce.huce2023-17(2)-01, ISSN：1859-2996, eISSN：2734-9489, 共同研究・競争的資金等ID：44511245
• Assessment of Dispersed Oil Sorption in Oily Wastewater onto Hydrophobized/Oleophilized Autoclaved Aerated Concrete (AAC) Grains
  Akihiro Matsuno; Ken Kawamoto
  Environments, 巻：10, 号：6, 開始ページ：92, 終了ページ：92, 2023年05月, ［査読有り］, ［最終著者］
  The discharge of untreated oily wastewater into the environment has serious impacts on human health, living nature, and ecosystems and leads to significant economic losses. Many engineering techniques have been proposed and applied to treat oily wastewater, but limited studies have investigated low-cost and effective techniques using by-products and waste/scrap materials from the construction industry. Materials to treat oily wastewater are needed not only to mitigate environmental pollution but also to promote the reuse and recycling of industrial by-products, especially in developing countries. This study, therefore, examined the sorption capacity of dispersed oil in wastewater (dispersed soybean oil in water; initial oil concentrations, Ci = 10–1000 mg/L; oil droplet size in water <2 μm) onto the hydrophobized/oleophilized autoclaved porous aerated concrete (AAC) grains made from waste scrap in Vietnam by using batch sorption tests in the laboratory. The AAC grains (sizes 0.106–0.25, 0.25–0.85, and 0.85–2.00 mm) were hydrophobized/oleophilized using oleic and stearic acids (coating concentrations of 1.0, 5.0, and 10 g/kg), and two sands (0.18–2.00 and 0.30–2.00 mm) were used as control samples. The results showed that the hydrophobized/oleophilized AAC grains had high sorption capacity for dispersed oil (i.e., high oil removal efficiency) compared to the control sands. Especially, the removal of AAC grains coated with stearic acid was >80% in high oil concentration solutions (Ci = 100 and 1000 mg/L), indicating that the hydrophobized/oleophilized AAC grains have high potential as useful adsorbents to trap dispersed oil in oily wastewater. Moreover, adsorption isotherms were drawn to examine the sorption characteristics of dispersed oil onto AAC grains. For all tested samples, the sorption of dispersed oil increased linearly with increasing equilibrium concentration. The commonly used Langmuir model, on the other hand, did not capture the measured isotherms.
  MDPI AG, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.3390/environments10060092
  DOI ID：10.3390/environments10060092, eISSN：2076-3298, 共同研究・競争的資金等ID：44511245
• Review on water and heat balance and challenges for the adoption of permeable pavement system in Vietnam　　　　　　　　　　　　　　　
  Pham, V.N.; K. Kawamoto; T.D. Nguyen; T.K. Tong; H.G. Nguyen
  International Journal of GEOMATE, 巻：24, 号：103, 2023年03月, ［査読有り］
  International Journal of Geomate, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.21660/2023.103.g12169
  DOI ID：10.21660/2023.103.g12169, ISSN：2186-2982, eISSN：2186-2990, 共同研究・競争的資金等ID：44511245
• Đánh giá khả năng xử lý Cadmi trong nước thải của bê tông khí chưng áp (AAC)
  Trần Hoài Sơn; Trần Thị Việt Nga; Ken Kawamoto
  Tạp chí Khoa học Công nghệ Xây dựng (KHCNXD) - ĐHXDHN, 巻：17, 号：1V, 開始ページ：1, 終了ページ：10, 2023年02月, ［査読有り］, ［最終著者］
  Bê tông khí chưng áp (AAC) là vật liệu rỗng xốp (độ rỗng tổng >70%), thành phần hóa học giàu canxi và các kim loại khác (Fe, Al, K, Mg). AAC cho thấy tiềm năng là chất hấp phụ hiệu quả các kim loại nặng (KLN) đặc biệt là Cadmi trong nước thải. Quá trình công nghiệp hóa trong ngành xây dựng và xu hướng giảm, không sử dụng các vật liệu nung truyền thống đã làm gia tăng quy mô sản xuất và sử dụng vật liệu AAC từ đó làm phát sinh hàng trăm nghìn mét khối AAC phế thải. Việc tái sử dụng chất thải AAC cho mục đích xử lý nước thải có ý nghĩa thực tiễn lớn khi giải quyết được bài toán quản lý chất thải rắn và xử lý KLN kiểm soát ô nhiễm môi trường nước. Trong nghiên cứu này, AAC đã được thử nghiệm như chất hấp phụ để loại bỏ Cd(II) ra khỏi nước thải. Các thí nghiệm hấp phụ tĩnh đã được thực hiện bằng cách sử dụng bê tông thải AAC với 2 kích cỡ khác nhau 3-5 mm và 5-10 mm để xử lý nước thải tổng hợp có nồng độ Cd(II) từ 0-5000 mg/L, trong các thời gian phản ứng khác nhau để đánh giá thời gian hấp phụ cân bằng và dung lượng hấp phụ cực đại của vật liệu. Kết quả nghiên cứu đã xác định được các thông số động học hấp phụ theo mô hình Langmuir và dung lượng hấp phụ Cd(II) của AAC lên đến 9,26 mg/g, từ đó chứng minh AAC có thể được sử dụng làm vật liệu hấp phụ chi phí thấp, hiệu quả, thân thiện, bền vững trong việc loại bỏ Cd(II) trong nước thải.
  Hanoi University of Civil Engineering (HUCE), ベトナム語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.31814/10.31814/stce.huce(nuce)2023-17(1v)-01
  DOI ID：10.31814/10.31814/stce.huce(nuce)2023-17(1v)-01, ISSN：2615-9058, eISSN：2734-9268, 共同研究・競争的資金等ID：44511245
• Applicability of Alkaline Waste and By-products as Low Cost Alternative Neutralizers for Acidic Soils
  Isiri Upeksha Nagasinghe; Takeshi Saito; Takato Takemura; Ken Kawamoto; Toshiko Komatsu; Naoki Watanabe; Yoshishige Kawabe
  ISIJ International, 巻：63, 号：2, 開始ページ：228, 終了ページ：234, 2023年02月, ［査読有り］
  Iron and Steel Institute of Japan, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2355/isijinternational.isijint-2022-247
  DOI ID：10.2355/isijinternational.isijint-2022-247, ISSN：0915-1559, eISSN：1347-5460
• Porosity and permeability of pervious concrete using construction and demolition waste in Vietnam　　　　　　　　　　　　　　　
  Tuan, K.N.; P.Q. Minh; K. Kawamoto; N.H. Giang; N.T. Dung
  International Journal of GEOMATE, 巻：24, 号：101, 2023年01月, ［査読有り］
  International Journal of Geomate, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.21660/2023.101.3511
  DOI ID：10.21660/2023.101.3511, ISSN：2186-2982, eISSN：2186-2990, 共同研究・競争的資金等ID：44511245
• Application of Autoclaved Aerated Concrete Grains Coated with Stearic Acid for Removal of Oil from Water
  Huyen T. T. Dang; Cuong Q. Le; Son H. Tran; Ken Kawamoto; Nga T. V. Tran; Pham Thanh Huyen
  Water, Air, & Soil Pollution, 巻：233, 号：12, 2022年12月, ［査読有り］
  Springer Science and Business Media LLC, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11270-022-05941-x
  DOI ID：10.1007/s11270-022-05941-x, ISSN：0049-6979, eISSN：1573-2932, 共同研究・競争的資金等ID：44511245
• Gas transport parameters of differently compacted granulated bentonite mixtures (GBMs) under air-dried conditions　　　　　　　　　　　　　　　
  Mazhar Nazir; Ken Kawamoto; Toshihiro Sakaki; Toshiko Komatsu; Per Moldrup
  Soils and Foundations, 巻：62, 号：6, 開始ページ：101223, 終了ページ：101223, 2022年12月, ［査読有り］
  Elsevier BV, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.sandf.2022.101223
  DOI ID：10.1016/j.sandf.2022.101223, ISSN：0038-0806, 共同研究・競争的資金等ID：44511237
• Hydrophobicity/Oleophilicity of Autoclaved Aerated Concrete (AAC) Grains Coated with Oleic and Stearic Acids for Application as Oil/Water Separating Filtration and Adsorbent Materials in Vietnam
  Akihiro Matsuno; Ken Kawamoto
  Environments, 巻：9, 号：8, 開始ページ：101, 終了ページ：101, 2022年08月, ［査読有り］, ［最終著者］
  Separation of oil and water is an effective technique to treat oily wastewater. For examining the applicability of porous grains coated with hydrophobic agents (HA) as low-cost and easily available filtration and adsorbent materials in the separation of oil and water, this study assessed the hydrophobicity/oleophilicity of porous grains made from autoclaved aerated concrete scrap coated with low-cost and harmless hydrophobic agents such as oleic and stearic acids. Tests using a sessile droplet method showed unique relationships between the contact angles (CA) of water droplets in air (CAwa), oil droplets in water (CAow) and coated HA concentrations. The CAwa increased linearly with increasing HA concentration and then became almost constant and/or gently increased after a specific point, indicating that a minimum coating amount gives the maximum hydrophobicity to HA-coated porous grains exists. The CAow gradually decreased exponentially with increasing HA concentration. In particular, the CAow of porous grains coated with stearic acid decreased with increasing of HA concentration in a two-step process. Furthermore, analyses of the Pearson correlation showed that both CAwa and CAow correlated well with the specific surface area (SSA), implying that the SSA is a good indicator as a quick assessment of hydrophobicity/oleophilicity of HA-coated porous grains.
  MDPI AG, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.3390/environments9080101
  DOI ID：10.3390/environments9080101, eISSN：2076-3298, 共同研究・競争的資金等ID：44511245
• Management Assessment and Future Projections of Construction and Demolition Waste Generation in Hai Phong City, Vietnam
  Kien Ton Tong; Ngoc Tan Nguyen; Giang Hoang Nguyen; Tomonori Ishigaki; Ken Kawamoto
  Sustainability, 巻：14, 号：15, 開始ページ：9628, 終了ページ：9628, 2022年08月, ［査読有り］, ［最終著者］
  Along with economic development, urbanization will generate a large amount of solid waste and put pressure on the waste management systems in developing countries. Face-to-face interview methods were used to investigate the current status of construction and demolition waste (CDW) management (collection, transportation, treatment, and storage) as well as reveal attitudes of governmental agencies and enterprises towards CDW recycling and recycled material products in Hai Phong City, Vietnam. Waste generation rates (WGRs) of the works were also determined by site surveys and as-built drawings method of typical old buildings to be demolished and two licensed new construction works. WGRs of 34.5 kg/m2 and 758 kg/m2 were identified during the construction and demolition of small private houses, respectively, while WGRs at public house demolition sites were 1053 kg/m2. To effectively manage the CDW, the gross floor area of new construction work was estimated by a multiple regression equation with the population and gross region domestic product growth. Based on this model combining the investigation results, the amount of CDW increase in 5–30 years is also predicted. This data set will help management agencies plan storage yards as well as select the appropriate CDW treatment and recycling methods, contributing to building a sustainable and effective CDW management model for Hai Phong City as well as Vietnam in the future.
  MDPI AG, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.3390/su14159628
  DOI ID：10.3390/su14159628, eISSN：2071-1050, 共同研究・競争的資金等ID：44511245
• Current state of building demolition and potential for selective dismantling in Vietnam　　　　　　　　　　　　　　　
  Ngoc Han Hoang; Tomonori Ishigaki; Takuma Watari; Masato Yamada; Ken Kawamoto
  Waste Management, 巻：149, 開始ページ：218, 終了ページ：227, 2022年07月, ［査読有り］, ［最終著者］
  Elsevier BV, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.wasman.2022.06.007
  DOI ID：10.1016/j.wasman.2022.06.007, ISSN：0956-053X, 共同研究・競争的資金等ID：44511245
• Laterite grains as a low-cost adsorbent to treat heavy metal-contaminated water: A review　　　　　　　　　　　　　　　
  Bandara, A.B.P.; K. Kawamoto
  International Journal of GEOMATE, 巻：22, 号：94, 2022年06月, ［査読有り］, ［最終著者］
  International Journal of Geomate, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.21660/2022.94.3228
  DOI ID：10.21660/2022.94.3228, ISSN：2186-2982, eISSN：2186-2990, 共同研究・競争的資金等ID：44511245
• Permanent Deformation and Breakage Response of Recycled Concrete Aggregates under Cyclic Loading Subject to Moisture Change
  Syed Kamran Hussain Shah; Taro Uchimura; Ken Kawamoto
  Sustainability, 巻：14, 号：9, 開始ページ：5427, 終了ページ：5427, 2022年04月, ［査読有り］, ［最終著者］
  Natural granular materials widely used in building and infrastructure development consume a considerable number of natural resources. To avoid depleting natural granular materials, recycled concrete aggregates (RCA) from construction and demolition waste are now commonly used as an alternative. The mechanical behavior of RCA used in road construction is highly influenced by field conditions such as traffic load and moisture variation. The particle breakage of RCA influences long-term pavement performance because it changes the RCA grading over time. However, the effect of moisture content (m.c.) on mechanical behavior and particle breakage during compaction and cyclic loading is often neglected. The aims of the study were to investigate the mechanism of permanent deformation development due to moisture change, the breakage response of RCA in this process, and the assessment of existing permanent deformation prediction model. The results showed that initial m.c. effectively controlled the deformation of RCA; the permanent axial strain (εpa) was enhanced, and the breakage of coarse fraction (19~9.5 mm) under cyclic loading was reduced at higher levels of m.c. Based on the experimental results, a modified model for predicting εpa was proposed, incorporating a deviation factor induced by m.c. The model fitted the experimental data well, suggesting that it is useful to have a quantitative estimation of εpa of RCA with different m.c. under cyclic loading.
  MDPI AG, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.3390/su14095427
  DOI ID：10.3390/su14095427, eISSN：2071-1050, 共同研究・競争的資金等ID：44511245
• Mechanical and Hydraulic Properties of Recycled Concrete Aggregates Mixed with Clay Brick Aggregates and Particle Breakage Characteristics for Unbound Road Base and Subbase Materials in Vietnam
  Trong Lam Nguyen; Van Tuan Nguyen; Hoang Giang Nguyen; Akihiro Matsuno; Hirofumi Sakanakura; Ken Kawamoto
  Sustainability, 巻：14, 号：8, 開始ページ：4854, 終了ページ：4854, 2022年04月, ［査読有り］, ［最終著者］
  The construction industry is one of the key industries with high potential for the circular economy; the promotion of reuse and recycling of construction and demolition waste (CDW) is essential for sustainable urban development. In this study, a series of compaction, California bearing ratio, saturated hydraulic conductivity, and particle breakage tests of well– and poor–graded mixtures of recycled clay brick aggregates (RCBs) and recycled concrete aggregates (RCAs) with maximum aggregate diameters of 19, 25, and 37.5 mm were carried out to examine the practical application of those mixtures to unbound roadbed materials in Vietnam. The experimental results suggest that the maximum amount of RCBs added to RCAs should be less than 30% when applied to unbound roadbed materials. In addition, it was found that the mixing proportions of RCBs and RCAs and the maximum aggregate diameter, gradation of aggregates, and initial moisture condition control the saturated hydraulic conductivity. Further, the particle breakage characteristics under compaction were carefully examined, and it was found that the percentage increment/decrement, as well as a newly introduced method of estimating the mixing proportions of RCAs and RCBs in the fine fraction (<2.36 mm), is effective in understanding the mechanism of particle breakage of RCA and RCB mixtures.
  MDPI AG, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.3390/su14084854
  DOI ID：10.3390/su14084854, eISSN：2071-1050, 共同研究・競争的資金等ID：44511245
• Characterization of Physicochemical and Mechanical Properties of Dumped Municipal Solid Waste in Sri Lanka as Affected by the Climate Zone and Dumping Age
  Muhammad Rashid Iqbal; Abeywickrama Bamunusin Kankanamge Thilini Piumali; Nadeej Hansaraj Priyankara; Alagiyawanna Mohottalalage Nayana Alagiyawanna; Laksiri Chandana Kurukulasuriya; Ken Kawamoto
  Sustainability, 巻：14, 号：8, 開始ページ：4706, 終了ページ：4706, 2022年04月, ［査読有り］, ［最終著者］
  Due to the rapid increase in population and urbanization, municipal solid waste (MSW) generation is increasing. Sri Lanka, in particular, faces serious difficulties in finding new sites for MSW disposal, due to the lack of available space; therefore, the rehabilitation of existing MSW dumping sites and the extension of their services are required to achieve sustainable urban development. To examine suitable rehabilitation techniques, it is essential to identify the physicochemical and mechanical properties of dumped MSW, fully considering climatic conditions, waste composition, and the time since the waste was dumped. In this study, therefore, the physicochemical and mechanical properties of dumped MSW were investigated; the dumped MSW was taken from existing MSW dumping sites in three climate zones in Sri Lanka, namely the Karadiyana site in the wet zone, Udapalatha in the intermediate zone, and Hambantota in the dry zone, and it was taken at different times after being dumped. The results showed that the waste composition and biodegradation of organic materials affected the physicochemical and mechanical properties of the dumped waste. The measured compaction parameters of the “old” sites at Udapalatha and Hambantota were higher compared to the “new” sites. Compaction parameters at the Karadiyana site, on the other hand, were low, at even >20 years since being dumped, probably due to the high amount of scarcely compacted materials. In direct shear tests, both strain hardening and softening of the waste samples were observed, depending on the difference in vertical stress. Based on the Pearson correlations among measured physicochemical and mechanical parameters, it was found that the loss on ignition (LOI) would be a good indicator to quickly assess the mechanical parameters of “new” and “old” waste materials, due to the small sensitivities to waste age and climate conditions in Sri Lanka. In particular, LOI correlated well to measured specific gravity and compaction properties, and the r2 values of correlations exceeded |0.80|.
  MDPI AG, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.3390/su14084706
  DOI ID：10.3390/su14084706, eISSN：2071-1050, 共同研究・競争的資金等ID：44511249
• Experimental studies on behaviors of reinforced concrete column structures made of recycled aggregates under concentric loads
  Nguyen Thanh Quang; Tran Viet Cuong; Nguyen Ngoc Tan; Nghiem Ha Tan; Ken Kawamoto; Nguyen Hoang Giang
  Journal of Science and Technology in Civil Engineering (STCE) - HUCE, 2022年04月, ［査読有り］
  The paper presents experimental results and structural analysis of reinforced concrete (RC) columns made of recycled aggregate concrete (RAC) and natural aggregate concrete (NAC) under concentric compressive load. The ratio of recycled aggregates in mixture (i.e, replacement ratio, r in %) was 0, 50, and 100% by mass, where r = 0% corresponding to NAC. The load and deformation curves including cracking load, ultimate load, crack width, and compressive strain of the tested columns, were analyzed to determine the effects of replacement ratio of recycled aggregate on the behaviors of square column structures. The results show that the increase of r reduced the load-carrying capacity of RC columns under the concentric compressive load. Horizontal and vertical cracks also were observed immediately for tested columns with high r. The effect of r of RAC on the mechanical behaviros, however, became relatively small and did not affect the behaviors of RAC columns, indicating that the RAC tested in this study was feasible for use in recycled concrete structures.
  Hanoi University of Civil Engineering (HUCE), 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.31814/stce.huce(nuce)2022-16(2)-01
  DOI ID：10.31814/stce.huce(nuce)2022-16(2)-01, ISSN：1859-2996, eISSN：2734-9489, 共同研究・競争的資金等ID：44511245
• Review on current situation of generation and management of coal ash in Vietnam　　　　　　　　　　　　　　　
  Tran, V.C.; K. Kawamoto; T.K. Tong; H.G. Nguyen
  International Journal of GEOMATE, 巻：22, 号：91, 2022年03月, ［査読有り］
  International Journal of Geomate, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.21660/2022.91.gxi316
  DOI ID：10.21660/2022.91.gxi316, ISSN：2186-2982, eISSN：2186-2990, 共同研究・競争的資金等ID：44511245
• Visualization of microstructure and measurement of mass transport parameters for granulated bentonite mixtures
  Mazhar Nazir; Akihiro Matsuno; Takeshi Saito; Ken Kawamoto; Toshihiro Sakaki
  Japanese Geotechnical Society Special Publication, 巻：9, 号：2, 開始ページ：26, 終了ページ：30, 2021年10月, ［査読有り］
  The Japanese Geotechnical Society, 研究論文（学術雑誌）
  DOI：https://doi.org/10.3208/jgssp.v09.cpeg121
  DOI ID：10.3208/jgssp.v09.cpeg121, eISSN：2188-8027
• Characterization of hydrophobicity for artificially hydrophobized autoclave aerated concrete grains
  Zafar Muhammad Junaid; Akihiro Matsuno; Takeshi Saito; Huyen Thi-Thanh Dang; Pham Thanh Huyen; Ken Kawamoto
  Japanese Geotechnical Society Special Publication, 巻：9, 号：8, 開始ページ：398, 終了ページ：402, 2021年10月, ［査読有り］
  The Japanese Geotechnical Society, 研究論文（学術雑誌）
  DOI：https://doi.org/10.3208/jgssp.v09.cpeg124
  DOI ID：10.3208/jgssp.v09.cpeg124, eISSN：2188-8027
• OIL/WATER SEPARATION TECHNIQUES USING HYDROPHOBIZED/OLEOPHILIZED GRAINS: A REVIEW OF RECENT STUDIES　　　　　　　　　　　　　　　
  Akihiro Matsuno; Zafar Muhammad Junaid; Takeshi Saito; Huyen Thi Thanh Dang; Pham Thanh Huyen; Tran Thi Viet Nga; Ken Kawamoto
  International Journal of GEOMATE, 巻：20, 号：81, 開始ページ：28, 終了ページ：34, 2021年05月, ［査読有り］, ［最終著者］
  Many domestic sources and industries, such as foods, textiles, metal industries, petrochemicals, and mining, produce massive volumes of oily wastewater all over the world. The insufficient treatment of oily wastewater in developing countries leads to serious environmental pollution and so on. In this review, we summarize many oil/water separation techniques to treat oily wastewater that have been developed such as flotation, chemical coagulation, biological treatment, filtration and membrane separation, and adsorption. Among them, oil/water separation techniques based on adsorption and filtration utilizing naturally hydrophilic sands and hydrophobized/oleophilized grains are worth attention due to their ease of application and cost effectiveness. In this review, we summarize recent studies on adsorption- and filtration-based oil/water separation techniques utilizing naturally hydrophilic sands and grains coated/modified with hydrophobic/oleophilic substances and compare the treatment performance, categorizing types of grains, coating substances, oil used, and testing methods. Prospects and challenges of oil/water separation studies are also given.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.21660/2021.81.6268
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85101586748&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85101586748&origin=inward
  DOI ID：10.21660/2021.81.6268, ISSN：2186-2982, SCOPUS ID：85101586748
• 荒川低地における不飽和帯の温度変化と二酸化炭素の生成と消失　　　　　　　　　　　　　　　
  斎藤健志; 川本健; 小松登志子
  土木学会論文集G（環境）, 巻：77, 号：3, 開始ページ：72, 終了ページ：82, 2021年, ［査読有り］
  Japan Society of Civil Engineers, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2208/jscejer.77.3_72
  DOI ID：10.2208/jscejer.77.3_72, ISSN：2185-6648, eISSN：2185-6648, J-Global ID：202102274435914559
• Characterization and comparison of groundwater quality and redox conditions in the Arakawa Lowland and Musashino Upland, southern Kanto Plain of the Tokyo Metropolitan area, Japan　　　　　　　　　　　　　　　
  Takeshi Saito; Lorenzo Spadini; Hirotaka Saito; Jean M. F. Martins; Laurent Oxarango; Takato Takemura; Shoichiro Hamamoto; Per Moldrup; Ken Kawamoto; Toshiko Komatsu
  SCIENCE OF THE TOTAL ENVIRONMENT, 巻：722, 2020年06月, ［査読有り］
  Groundwater is essential for the Earth biosphere but is often contaminated by harmful chemical compounds due to both anthropogenic and natural causes. A key factor controlling the fate of harmful chemicals in groundwater is the reduction/oxidation (redox) conditions. The formation factors for the groundwater redox conditions are insufficiently understood. In this study, long-term groundwater quality beneath one of the world megacities was monitored and evaluated. We measured and compared hydrogeochemical conditions including groundwater quality (35 chemical parameters) and redox conditions of five aquifers in the Arakawa Lowland and Musashino Upland, southern Kanto Plain of the TokyoMetropolitan area, Japan. Monitoring results suggested the following: The main origin of groundwater is precipitation in both the Lowland and Upland areas. The three aquifers in the Arakawa Lowland are likely fully separated, with one unconfined and two confined aquifers under iron reducing and methanogenic conditions, respectively. Oppositely, in the Musashino Upland, the water masses in the two aquifers are likely partly connected, under aerobic conditions, and undergoing the same groundwater recharge and flow processes under similar hydrogeological conditions. The different groundwater redox conditions observed are likely caused by the very different groundwater residence times for the Arakawa Lowland and Musashino Upland. (C) 2020 Elsevier B.V. All rights reserved.
  ELSEVIER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.scitotenv.2020.137783
  DOI ID：10.1016/j.scitotenv.2020.137783, ISSN：0048-9697, eISSN：1879-1026, Web of Science ID：WOS:000535470700002
• ベトナムにおける建設廃棄物の適正管理と建廃リサイクル資材を活用した環境浄化およびインフラ整備技術の開発　　　　　　　　　　　　　　　
  川本 健
  廃棄物資源循環学会誌, 巻：31, 号：1, 開始ページ：44, 終了ページ：50, 2020年, ［査読有り］, ［招待有り］, ［筆頭著者, 責任著者］
  日本語, 研究論文（学術雑誌）
  共同研究・競争的資金等ID：44511245
• Examination of crushed laterite brick for removal of chromium and arsenic from wastewater　　　　　　　　　　　　　　　
  Arachchillage Buddhika Priyadarshani Bandara; Gajanayaka Mudalige Pradeep Kumara; Akihiro Matsuno; Takeshi Saito; Tran Thi Viet Nga; Ken Kawamoto
  International Journal of GEOMATE, 巻：19, 号：74, 開始ページ：22, 終了ページ：30, 2020年, ［査読有り］, ［最終著者］
  Adsorption is one of the highly efficient methods to treat heavy metals in wastewater. Due to their economic feasibility, the use of locally available low-cost adsorbents has received much attention, especially in developing countries. The objective of this study was to investigate the applicability of laterite grains made from crushing laterite brick in Vietnam (0.105-2 mm) for the removal of chromium (Cr) and arsenic (As) from wastewater. For comparison, commercially available zeolite and Autoclaved Aerated Concrete (AAC) grains were tested. A series of laboratory tests for examining the effects of the initial metal concentration, initial solution pH, background ion concentration (ionic strength), and solid-to-liquid (S:L) ratio on adsorption and desorption characteristics were carried out. The test results showed that the Langmuir model captured well all obtained data in concentration range of 0-2,000 mg/L for laterite grains, suggesting that monolayer adsorption dominantly occurred. The measured maximum adsorption capacities of laterite grains were 8.2 mg/g and 1.3 mg/g for As and Cr, and the laterite grains gave a relatively high As adsorption compared to previously reported materials. The removal efficiencies of Cr and As were dependent on initial pH and S:L ratio, and lower initial pH and S:L ratio gave higher removal % for all tested adsorbents. Based on the results for desorption tests, laterite grains gave a higher hysteresis index for As (480%) compared to those from zeolite (128%) and AAC (176%), indicating that the tested laterite in this study possessed a strong irreversibility for adsorbed As (i.e. As immobilization). Consequently, laterite grains have a high potential as a low-cost adsorbent for As removal from wastewater.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.21660/2020.74.9176
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85088111674&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85088111674&origin=inward
  DOI ID：10.21660/2020.74.9176, ISSN：2186-2982, SCOPUS ID：85088111674
• Evaluation of Autoclaved Aerated Concrete Fines for Removal of Cd(II) and Pb(II) from Wastewater　　　　　　　　　　　　　　　
  G. M. P. Kumara; Ken Kawamoto; Takeshi Saito; Shoichiro Hamamoto; Shingo Asamoto
  JOURNAL OF ENVIRONMENTAL ENGINEERING, 巻：145, 号：11, 2019年11月, ［査読有り］
  Along with the increase of autoclaved aerated concrete (AAC) production, the amount of scrap waste (industrial by-products) is increasing. AAC waste, however, is not yet being fully reused or recycled and is discarded without any treatment in most developing countries. In this study, AAC fines were tested as effective and economic adsorbents for the removal of Cd2+ and Pb2+ from wastewater. A series of batch adsorption experiments were carried out using AAC with three different particle sizes (<0.105, 0.105-2, and 2-4.75 mm) to examine effects of the particle size, initial metal concentration (Ci), initial pH (pHi), ionic strength, contact time, and competitive metals. For comparing the adsorption characteristics and capacities, crushed concrete fines and a fine sand were also used. Results showed that the adsorption kinetic data were well fitted to the pseudo-second-order kinetics model for all tested materials. Pb2+ adsorption was independent of pHi and ionic strength for AAC fines, whereas Cd2+ adsorption varied depending on pHi and decreased drastically at pHi <= 7. Based on the results from adsorption isotherms, the Freundlich model fitted well (R2>0.90) to the data for 300 <= Ci <= 5,000 mg/L, whereas the Langmuir model was applicable (R2>0.99) to the data for Ci <= 2,000 mg/L. The maximum adsorption capacity of each particle size of AAC exhibited almost the same adsorption capacity for Cd2+ (15 mg/g) and Pb2+ (>250 mg/g), which are similar to or higher than the values of other types of adsorbents in previous studies. The metal removal by AAC is controlled mainly by ion exchange, surface complexation, and surface precipitation. In particular, the Ca2+ ion exchange on the hydrated adsorbent surface is the dominant adsorption mechanism at the early stage of adsorption. The selectivity sequence of metal adsorptions became Pb2+>Cu2+>Ni2+>Cd2+>Zn2+ for AAC, and the existence of Pb2+ and Cu2+ in wastewater highly impeded the Cd2+ adsorption onto AAC fines.
  ASCE-AMER SOC CIVIL ENGINEERS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1061/(ASCE)EE.1943-7870.0001597
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85071765777&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85071765777&origin=inward
  DOI ID：10.1061/(ASCE)EE.1943-7870.0001597, ISSN：0733-9372, eISSN：1943-7870, SCOPUS ID：85071765777, Web of Science ID：WOS:000486511200004
• Methane eruptions from landfill final cover soil during rainfall events in laboratory experiments　　　　　　　　　　　　　　　
  Satoshi Izumoto; Shoichiro Hamamoto; Ken Kawamoto; Masanao Nagamori; Taku Nishimura
  SOILS AND FOUNDATIONS, 巻：59, 号：4, 開始ページ：1052, 終了ページ：1062, 2019年08月, ［査読有り］
  Landfill sites are significant sources of greenhouse gases, particularly methane. It is believed that methane gas eruptions occur under a surface ponding condition during rainfall events. In this study, based on laboratory column experiments in which mixed gas was applied to variably compacted soil columns (10 cm in diameter and 30.5 cm in height) under different rainfall intensities, the effects of the bulk density of the landfill cover soil, the gas injection rates, and the rainfall intensities on the gas eruption phenomenon were investigated. The gas pressure and the water content were monitored during rainfall events. The main results were that (1) an episodic gas compression and eruption cycle was observed under a surface ponding condition, (2) gas eruptions occurred at a higher gas pressure in the soil with a higher dry bulk density, and (3) a higher gas injection rate resulted in continuous gas eruptions. The monitoring of the gas eruption flux and gas concentration in the soil columns, using oxygen-mixed gas as an injected gas, showed that longer gas compression led to higher gas fluxes during the gas eruptions. The concentration of gas in the soil increased over time because of the upward gas flow in accordance with the eruptions. The calculation of the oxygen mass balance indicated that the eruptions had slightly promoted the emission of gas from that which had been stored in the soil prior to the rainfall events. (C) 2019 Production and hosting by Elsevier B.V. on behalf of The Japanese Geotechnical Society.
  JAPANESE GEOTECHNICAL SOC, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.sandf.2019.05.002
  DOI ID：10.1016/j.sandf.2019.05.002, ISSN：0038-0806, Web of Science ID：WOS:000488957500020
• Linking pore network structure derived by microfocus X-ray CT to mass transport parameters in differently compacted loamy soils　　　　　　　　　　　　　　　
  Arjun Baniya; Ken Kawamoto; Shoichiro Hamamoto; Toshihiro Sakaki; Takeshi Saito; Karin Mueller; Per Moldrup; Toshiko Komatsu
  SOIL RESEARCH, 巻：57, 号：6, 開始ページ：642, 終了ページ：656, 2019年, ［査読有り］
  Mass transport in soil occurs through the soil pore network, which is highly influenced by pore structural parameters such as pore-size distribution, porosity, pore tortuosity, and coordination number. In this study, we visualised the networks of meso- and macro-pores (typical pore radius r >= 10 mu m) using microfocus X-ray computed tomography (MFXCT) and evaluated pore structural parameters of two loamy soils from Japan and New Zealand packed at different degrees of compaction. The effect of compaction on pore structural parameters and relationships between pore structural parameters and measured mass transport parameters were examined. Results showed a clear influence of compaction on pore structural parameters, with the MFXCT-derived mean pore radii and pore tortuosities decreasing and the mean pore coordination number increasing with increasing dry bulk density. Especially, pores with r > 80 mu m became finer or were not well formed due to compaction. The MFXCT-derived pore structural parameters were not well correlated with the equivalent pore radii from measured water retention curves. However, volumetric surface areas and pore-network connectivity-tortuosity factors derived from MFXCT allowed a fair prediction of several important mass transport parameters such as saturated hydraulic conductivities, soil-gas diffusion coefficients, and soil-air permeabilities. Further studies are needed to link micro-pores with radii smaller than the X-ray CT resolution to meso- and macro-pores visualised by X-ray CT to improve the prediction of mass transport parameters in soil.
  CSIRO PUBLISHING, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1071/SR18186
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85069515125&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85069515125&origin=inward
  DOI ID：10.1071/SR18186, ISSN：1838-675X, eISSN：1838-6768, SCOPUS ID：85069515125, Web of Science ID：WOS:000484546300012
• Saturation-dependent gas transport in sand packs: Experiments and theoretical applications　　　　　　　　　　　　　　　
  Behzad Ghanbarian; Shoichiro Hamamoto; Ken Kawamoto; Toshihiro Sakaki; Per Moldrup; Taku Nishimura; Toshiko Komatsu
  ADVANCES IN WATER RESOURCES, 巻：122, 開始ページ：139, 終了ページ：147, 2018年12月, ［査読有り］
  Understanding gas transport in porous media and its mechanism has broad applications in various research areas, such as carbon sequestration in deep saline aquifers and gas explorations in reservoir rocks. Gas transport is mainly controlled by pore space geometrical and morphological characteristics. In this study, we apply a physically-based model developed using concepts from percolation theory (PT) and the effective-medium approximation (EMA) to better understand diffusion and permeability of gas in packings of angular and rounded sand grains as well as glass beads. Two average sizes of grain i.e., 0.3 and 0.5 mm were used to pack sands in a column of 6 cm height and 4.9 cm diameter so that the total porosity of all packs was near 0.4. Water content, gas-filled porosity (also known as gas content), gas diffusion, and gas permeability were measured at different capillary pressures. The X-ray computed tomography method and the 3DMA-Rock software package were applied to determine the average pore coordination number z. Results showed that both saturation-dependent diffusion and permeability of gas showed almost linear behavior at higher gas-filled porosities, while deviated substantially from linear scaling at lower gas saturations. Comparing the theory with the diffusion and permeability experiments showed that the determined value of z ranged between 2.8 and 5.3, not greatly different from X-ray computed tomography results. The obtained results clearly indicate that the effect of the pore-throat size distribution on gas diffusion and permeability was minimal in these sand and glass bead packs.
  ELSEVIER SCI LTD, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.advwatres.2018.10.011
  DOI ID：10.1016/j.advwatres.2018.10.011, ISSN：0309-1708, eISSN：1872-9657, Web of Science ID：WOS:000450094200011
• Evaluation of applicability of filling materials in permeable reactive barrier (PRB) system to remediate groundwater contaminated with Cd and Pb at open solid waste dump sites　　　　　　　　　　　　　　　
  Udayagee Kumarasinghe; Ken Kawamoto; T. Saito; Y. Sakamoto; M. I.M. Mowjood
  Process Safety and Environmental Protection, 巻：120, 開始ページ：118, 終了ページ：127, 2018年11月, ［査読有り］
  This study aimed to identify appropriate filling materials for a permeable reactive barrier (PRB) system to treat groundwater contaminated with trace metals in the vicinity of solid waste landfills in Sri Lanka. Mixtures of alluvial loamy soil, coconut shell biochar, and laterite clay brick in different proportions were tested as easily-available PRB adsorbents. A series of adsorption and desorption experiments were carried out to investigate the effects of initial concentration, pH, ionic strength, and multiple competitive trace elements on Cd and Pb adsorption onto the tested adsorbents. In addition, hydraulic conductivities (Ks) of the tested adsorbents under different compaction levels were measured to examine a suitable packing condition for the PRB system. Results showed that the Langmuir model performed well for fitting Cd and Pb adsorption isotherms and maximum adsorption capacities (Qm) for Pb (2.1–15.3 mg/g) became higher than those for Cd (0.8–6.8 mg/g). All tested adsorbents showed low leaching of adsorbed metals with high hysteresis indices in desorption studies. In the multiple trace element solution, the existence of other trace metals (Cu, Zn, Ni) had a significant effect on Cd adsorption but less on Pb adsorption. The three mixed adsorbents had no dependency on the initial pH and ionic strength of the solution, while the single material showed a low dependency in both Cd and Pb adsorption. The inclusion of brick was effective to improve the hydraulic property and measured Ks values for the 75% brick mixed materials resulted of >10−4 cm/s at high compaction levels (Dr = 90% and 100%). Three mixed materials can be strongly recommended as a PRB filling material to treat landfill leachate based on their reactivity and hydraulic properties.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.psep.2018.09.003
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85053428787&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85053428787&origin=inward
  DOI ID：10.1016/j.psep.2018.09.003, ISSN：0957-5820, SCOPUS ID：85053428787, 共同研究・競争的資金等ID：44511249
• Monitoring of methane emission from a landfill site in daily and hourly time scales using an automated gas sampling system　　　　　　　　　　　　　　　
  Izumoto Satoshi; Hamamoto Shoichiro; Kawamoto Ken; Nagamori Masanao; Nishimura Taku
  ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH, 巻：25, 号：24, 開始ページ：24500, 終了ページ：24506, 2018年08月, ［査読有り］
  Landfill sites are significant sources of methane gas globally. Understanding the temporal variabilities of methane emissions from landfill sites is necessary for estimating such emissions. In this study, an automated monitoring system was used to monitor methane emission flux and concentration on daily and hourly time scales at a landfill site. Measured methane emission fluxes were almost negligible in the studied area. However, methane concentration at landfill surface at nighttime was significantly higher than those in the daytime, which demonstrates the importance of investigating methane emissions at an hourly time scale, including during nighttime. The daily and hourly variations in methane concentration were well correlated with either soil temperature or volumetric water content near the surface. The obtained relations indicate that the automated monitoring system measurements can facilitate a more comprehensive understanding of the methane emission mechanisms at different time scales.
  SPRINGER HEIDELBERG, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11356-018-2671-1
  DOI ID：10.1007/s11356-018-2671-1, ISSN：0944-1344, eISSN：1614-7499, Web of Science ID：WOS:000441784000089
• Runoff and nutrient loss from a water-repellent soil　　　　　　　　　　　　　　　
  Karin Müller; Karen Mason; Alfonso Gastelum Strozzi; Robert Simpson; Toshiko Komatsu; Ken Kawamoto; Brent Clothier
  Geoderma, 巻：322, 開始ページ：28, 終了ページ：37, 2018年07月, ［査読有り］
  The effects of soil water repellency (SWR) on runoff and nutrient losses are difficult to isolate. Hydrophobic organic substances coating soil particles can severely delay water infiltration and enhance runoff. We used a portable run-on simulator to investigate the effect of SWR on runoff and nutrient loss. Intact soil slabs, 0.48 m long and 0.19 m wide, were collected from a severely water-repellent Andosol under pasture. One day before simulating 60-min long run-on events with an intensity of 60 mm h−1, superphosphate was applied at a rate of 45 kg P ha−1. The effects of SWR were quantified by comparing runoff volumes and nutrient losses from run-on events conducted with water and a fully wetting aqueous ethanol solution as run-on liquids. Further, through conducting multiple consecutive water run-on events with the same soil slab, the hypothesis, that SWR is lost through the washing off of hydrophobic materials, was tested. Finally, runoff dynamics were visualised by adding a dye to the run-on water. In the first run-on experiment, 88% of the water applied was captured as runoff, while no runoff was observed when aqueous ethanol was used as run-on liquid, providing strong evidence that SWR governed runoff generation from this Andosol. In consecutive water run-on experiments, approximately 23% of the applied P was recovered in the runoff from the first event, while the cumulative P loss over ten consecutive run-on events was around 30% of the applied P. This confirms that nutrient losses were associated with SWR and the occurrence of runoff. After ten consecutive run-on events, the persistence of both actual and potential SWR in areas of the slab that had been wetted were significantly (p <
  0.5) reduced. But the persistence of potential SWR of the soil was still classified as severe, suggesting only minor losses of hydrophobic materials from the soil surface. The persistence of potential SWR and the degree of SWR of the dry areas remained more or less unchanged. In accordance with this, visualisation of the wetted areas showed that runoff occurred as rivulets guided by surface topography, rather than as sheet flow, with the wetted area increasing from approximately 20% of the slab in the first event to around one third of the total slab area in the final event. This pattern is reflected in the cumulative pattern of the P losses over the ten events. Consequently, we conclude that SWR should be considered as a factor in hydrological modelling and should be included in models to address appropriately the risk of surface water contamination by solutes exogenously applied to water-repellent soils.
  Elsevier B.V., 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.geoderma.2018.02.019
  DOI ID：10.1016/j.geoderma.2018.02.019, ISSN：0016-7061, SCOPUS ID：85042317407
• Reviews on the applicability of construction and demolition waste as low-cost adsorbents to remove-heavy metals in wastewater　　　　　　　　　　　　　　　
  G. M.P. Kumara; Takeshi Saito; Shingo Asamoto; Ken Kawamoto
  International Journal of GEOMATE, 巻：14, 号：42, 開始ページ：44, 終了ページ：51, 2018年, ［査読有り］, ［最終著者］
  Removal of heavy metals from wastewater is of special concern due to the persistence of heavy metals in the environment. The industrial discharge of heavy metals adversely affects soil and water resources, aquatic organisms, and ecosystem integrity. In addition, high concentrations of heavy metals are detected in solid waste landfill leachate in many developing countries due to non-segregated waste dumping. At present, various kinds of adsorbents such as activated carbon, biomass resources, geomaterials, and industrial waste products are used to treat heavy metal-contaminated water. However, the use of construction and demolition waste (CDW) and its recycled materials to treat heavy metal-contaminated water has not been fully examined. Because the generation of CDW is increasing due to rapid urbanization and a high demand for construction, the wise use of CDW and its recycled materials is necessary. This paper reviews journal articles published from 2004 to 2016 that studied the applicability of low-cost CDW adsorbents to remove heavy metals from wastewater. In particu-lar, it summarizes results on using CDW and recycled materials such as cement, concrete, and brick compared to those from various other adsorbents such as biosorbents, geomaterials, and their industrial products. The poten-tial applicability of CDW and its recycled materials as heavy-metal adsorbents was examined based on a com-parison table listing material properties, test conditions, and measured adsorption properties.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.21660/2018.42.7148
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85040908556&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85040908556&origin=inward
  DOI ID：10.21660/2018.42.7148, ISSN：2186-2982, SCOPUS ID：85040908556, 共同研究・競争的資金等ID：44511249
• Effectiveness of permeable reactive barrier (PRB) on heavy metal trap in aquifer at solid waste dumpsite: A simulation study　　　　　　　　　　　　　　　
  Udayagee Kumarasinghe; Y. Sakamoto; T. Saito; M. Nagamori; C. S. Kalpage; G. B. Herath; M. I.M. Mowjood; Ken Kawamoto
  International Journal of GEOMATE, 巻：15, 号：51, 開始ページ：225, 終了ページ：232, 2018年, ［査読有り］, ［最終著者］
  Open dumping of solid waste causes a serious environmental impact on groundwater due to contamination of landfill leachate rich in heavy metals. Identification of contaminant flow and implementation of remediation technologies, such as permeable reactive barriers (PRB) are highly demanded and applicable. In this study, a groundwater model, Geo-Environmental Risk Assessment System (GERAS) has been used to simulate two-dimensional heavy metal transport in an aquifer at solid waste dumpsite and to estimate the effectiveness of virtual PRB on trap heavy metals. First, two cases were examined: 1) Open dumping of waste located above the aquifer and 2) Buried dumping of waste into the aquifer. Concentration changes of heavy metals (Cd and Pb) inside the aquifer beneath the waste unit, inside PRB, upstream and downstream points to PRB were examined by changing the hydraulic gradient, distribution coefficient, and pollution load. Results showed the numerical simulations well captured the wash-out process of heavy metals from the pollutant source. The time required for full wash-out was highly dependent on the hydraulic gradient, distribution coefficient, pollution load and the way of waste dumping. In Case 2, a sudden pollution plume was observed with high heavy metal concentrations, by creating greater risk at the downstream. Next, a virtual PRB was set in downstream of the aquifer by installing a section with a high heavy metal adsorption capacity (based on previous studies). Results showed that in both cases, the virtual PRB well trapped the target metals and reduced the contamination level less than the effluent water quality standards.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.21660/2018.51.7179
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85048772836&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85048772836&origin=inward
  DOI ID：10.21660/2018.51.7179, ISSN：2186-2982, SCOPUS ID：85048772836, 共同研究・競争的資金等ID：44511249
• 温度変化が堆積物からのホウ素およびヒ素の溶出量とその存在形態に及ぼす影響　　　　　　　　　　　　　　　
  斎藤 健志; 濱本 昌一郎; 竹村 貴人; 上島 雅人; 川本 健; 小松 登志子
  土木学会論文集Ｇ（環境）, 巻：74, 号：1, 開始ページ：8, 終了ページ：15, 2018年, ［査読有り］
  温度変化が堆積物からのホウ素とヒ素の溶出量と存在形態に及ぼす影響を解明することを目的に，荒川低地中部で深度50 mまでのボーリングにより採取した4試料を用い，嫌気的条件および異なる温度条件下（15℃，25℃，40℃）で溶出試験（水溶性を分画）を行った．溶出試験後の試料に対し，逐次抽出法試験（イオン交換態，炭酸塩態，鉄・マンガン酸化物態，有機物態，残渣に分画）を適用した．溶出試験でホウ素とヒ素の水溶性画分に温度効果が顕著であった堆積物について，水溶性，イオン交換態，炭酸塩態の量を足し合わせた最大溶出可能量は，温度上昇とともに増加する傾向が確認された．一方，鉄・マンガン酸化物態は減少傾向にあり，この画分から溶出しやすい存在形態（水溶性，イオン交換態，炭酸塩態）へと温度上昇により移行した可能性が考えられた．
  公益社団法人 土木学会, 日本語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2208/jscejer.74.8
  DOI ID：10.2208/jscejer.74.8, eISSN：2185-6648, CiNii Articles ID：130006386873
• Closure to discussion of “Pore network structure linked by X-ray CT to particle characteristics and transport parameters” by Hamamoto S., Moldrup P., Kawamoto K., Sakaki T., Nishimura T., and Komtatsu, T　　　　　　　　　　　　　　　
  Shoichiro Hamamoto; Per Moldrup; Ken Kawamoto; Toshihiro Sakaki; Taku Nishimura; Toshiko Komatsu
  Soils and Foundations, 巻：57, 号：5, 開始ページ：901, 終了ページ：903, 2017年10月, ［査読有り］
  Japanese Geotechnical Society, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.sandf.2017.08.016
  DOI ID：10.1016/j.sandf.2017.08.016, ISSN：0038-0806, SCOPUS ID：85030647903
• Characterization of locally available soil as a liner material for solid waste landfills in Sri Lanka　　　　　　　　　　　　　　　
  Hafiz Muhammad Awais Rashid; J. A.D.K. Wanigarathna; L. C. Kurukulasuriya; N. H. Priyankara; A. M.N. Alagiyawanna; Takeshi Saito; Ken Kawamoto
  Environmental Earth Sciences, 巻：76, 号：11, 2017年06月, ［査読有り］, ［最終著者］
  This study aimed to develop a low-cost and effective clay liner material for solid waste landfills in Sri Lanka. A locally available clayey soil and its admixtures with 5 and 10% bentonite were examined for this purpose. Laboratory experiments to determine soil plasticity and swell index were carried out on the tested samples. Hydraulic conductivity (k) tests were carried out in the laboratory using water and an aqueous solution of CaCl2 on unconsolidated samples prepared by either dry or slurry packing and pre-consolidated samples with five different consolidation pressures (p) from 10 to 200 kPa. Measured liquid limits for tested admixtures increased with increasing bentonite contents and correlated well with measured values of the swell index. The difference in permeant solutions had little effect on measured k values for both unconsolidated and pre-consolidated samples. The hydraulic conductivities were highly affected by changing p, i.e., the k values decreased on two orders of magnitude as p increased from 10 to 200 kPa. The Kozeny–Carman equation, a theoretical permeability model that expresses the k-porosity relationship, was applied to measured data including reported values. Results showed the Kozeny–Carman equation captured well the porosity-dependent k values for tested soils and their admixtures with bentonite under a wide range of void ratios, suggesting that the Kozeny–Carman equation is a useful tool to estimate the magnitude of k values for differently compacted soil and its bentonite admixtures.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s12665-017-6717-3
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85020045112&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85020045112&origin=inward
  DOI ID：10.1007/s12665-017-6717-3, ISSN：1866-6280, eISSN：1866-6299, SCOPUS ID：85020045112, 共同研究・競争的資金等ID：44511249
• Microcosm experiments on a coconut-fibre biofilm treatment system to evaluatewaste water treatment efficiencies　　　　　　　　　　　　　　　
  Naofumi Sato; W. N.K. Dharmarathne; Takeshi Saito; Hiroyasu Sato; Norio Tanaka; Ken Kawamoto
  International Journal of GEOMATE, 巻：12, 号：33, 開始ページ：160, 終了ページ：166, 2017年05月, ［最終著者］
  Interest in utilization of locally available biomasses as biofilm support media for wastewater treatment in developing countries is increasing. In this study, microcosm experiments on a coconut-fibre biofilm treatment system were carried out to evaluate wastewater treatment efficiencies in the laboratory using two wastewaters, synthetic sewage and leachate, with different pollutant loads. Three coconut-fibre conditions were set as a single bundle (low fibre density: LFD), two bundles (high fibre density: HFD), and no coconut fibre (blank). The wastewater was first circulated in the system for six weeks (circulation stage) and then discharged from the treatment tank for 7-24 weeks (treatment stage). Water quality parameters of effluents, pH, DO, EC, BOD, COD, TC, and TN, were measured at one-week intervals, and the sedimented sludge in each treatment tank was collected to determine C, N, and P contents. Results showed effective reductions in BOD and COD in the LFD and HFD conditions for the synthetic leachate, indicating that the coconut fibre contributed to the treatment of wastewater. On the other hand, the fibre density had less or no effect on the reduction of water quality parameters in the synthetic sewage. For both synthetic sewage and leachate, the C and N consumptions generally increased in the order of blank, LFD, and HFD. In particular, sludge sedimentation contributed to C consumption under the HFD condition.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.21660/2017.33.2754
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85018239515&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85018239515&origin=inward
  DOI ID：10.21660/2017.33.2754, ISSN：2186-2982, SCOPUS ID：85018239515, 共同研究・競争的資金等ID：44511249
• Temporal variations in perched water and groundwater qualities at an open solid waste dumpsite in Sri Lanka　　　　　　　　　　　　　　　
  Udayagee Kumarasinghe; Y. Inoue; T. Saito; M. Nagamori; Y. Sakamoto; M. I.M. Mowjood; K. Kawamoto
  International Journal of GEOMATE, 巻：13, 号：38, 開始ページ：1, 終了ページ：8, 2017年
  Open dumping of municipal solid waste is a common practice in many developing countries and contaminates surface and groundwater in the vicinity. In this study, long-term monitoring was conducted at an abandoned solid waste dumpsite to characterize temporal variations of perched water and groundwater qualities. The dumpsite was located at Udapalatha PS in Central Province of Sri Lanka and consisted of two sections (namely Old and New sections). The Old section was used for waste dumping for seven years from 2003 to 2010, and the New section was used for six months in 2011. Multiple wells were installed at each section and water qualities monitored for two years from May 2013 to March 2015. Water quality parameters such as pH, EC, BOD, COD, TN, TP, major cations, major anions, and heavy metals were measured monthly. Leachate pollution index (LPI) was used to quantify the leachate contamination potential of landfill site. Results showed that groundwater samples from both Old and New sections exhibited relatively low LPI during the monitoring period, whereas perched water samples from New section showed high LPI with fluctuations. At the monitoring site, perched water and groundwater seem to persist as two independent bodies for both Old and New sections. Especially, the dumped waste at lower layer at the Old section was fully washed out by rainfall and surface water after waste dumping and currently carries a low risk of groundwater contamination.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.21660/2017.38.2761
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85020117172&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85020117172&origin=inward
  DOI ID：10.21660/2017.38.2761, ISSN：2186-2982, SCOPUS ID：85020117172
• Coconut-Fibre Biofilm Wastewater Treatment System in Sri Lanka: Microcosm Experiments for Evaluating Wastewater Treatment Efficiencies and Oxygen Consumption
  Naofumi Sato; Takeshi Saito; Hiroyasu Satoh; Norio Tanaka; Ken Kawamoto
  International Journal of Environmental Science and Development, 巻：8, 号：10, 開始ページ：691, 終了ページ：695, 2017年, ［査読有り］, ［最終著者］
  EJournal Publishing, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.18178/ijesd.2017.8.10.1040
  DOI ID：10.18178/ijesd.2017.8.10.1040, eISSN：2010-0264, 共同研究・競争的資金等ID：44511249
• Characterization of temporal variations in landfill gas components inside an open solid waste dump site in Sri Lanka　　　　　　　　　　　　　　　
  Masanao Nagamori; M. I. M. Mowjood; Youichi Watanabe; Yugo Isobe; Tomonori Ishigaki; Ken Kawamoto
  JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 巻：66, 号：12, 開始ページ：1257, 終了ページ：1267, 2016年12月, ［査読有り］
  A long-term monitoring of composition of landfill gases in the region with high rainfall was conducted using an argon assay in order to discuss air intrusion into the dump site. Gas samples were taken from vertical gas monitoring pipes installed along transects at two sections (called new and old) of an abandoned waste dump site in Sri Lanka. N2O concentrations varied especially widely, by more than three orders of magnitude (0.046-140 ppmv). The nitrogen/argon ratio of landfill gas was normally higher than that of fresh air, implying that denitrification occurred in the dump site. Argon assays indicate that both N-2 and N2O production occurred inside waste and more significantly in the old section. The Ar assay would help for evaluations of N2O emission in developing countries.Implications: A long-term monitoring of composition of landfill gases in the region with high rainfall was conducted using an argon assay in order to discuss air intrusion into the dump site. Argon assays indicate that both N-2 and N2O production occurred inside waste and more significantly in the old section.
  TAYLOR & FRANCIS INC, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1080/10962247.2016.1212746
  DOI ID：10.1080/10962247.2016.1212746, ISSN：1096-2247, eISSN：2162-2906, Web of Science ID：WOS:000387785100010
• Characterizing volatile organic compounds in leachate from Gohagoda municipal solid waste dumpsite, Sri Lanka　　　　　　　　　　　　　　　
  Prasanna Kumarathilaka; Yohan Jayawardhana; B. F.A. Basnayake; M. I.M. Mowjood; M. Nagamori; Takeshi Saito; Ken Kawamoto; Meththika Vithanage
  Groundwater for Sustainable Development, 巻：2-3, 開始ページ：1, 終了ページ：6, 2016年08月, ［査読有り］
  Fate and transport of volatile organic compounds (VOCs) in landfill leachate causes environmental pollution and human health concern. These VOCs can directly be emitted to the atmosphere and also can end up in leachate plume from open solid waste dumpsites. However, no data exists on the VOCs in landfill leachate in Sri Lanka. Hence, the purpose of this study was to assess the variation of VOCs in landfill leachate at the Gohagoda Municipal Solid Waste (MSW) dumpsite, Kandy, Sri Lanka in a dry (Spring) and a wet (Autumn) month. A list of the key offensive VOCs covering 13 chemicals in leachate was quantified by using a head space-gas-chromatography-mass-spectrometry (HS-GC-MS). Results indicated that benzene and toluene were most commonly observed in both sampling periods, ranging from 1.78-21.7 and 1.73-20.2 μg L-1, respectively. 4-Isopropyltoluene had the highest concentrations of the VOCs investigated in both sampling periods (38.0 and 129 μg L-1 in spring and autumn, respectively). Totally, 9 different VOCs out of 13 listed were detected in the landfill leachate. In comparison, the number of VOCs and total VOC concentrations were higher at all sampling locations in spring except GSV1 sampling point. Thereby, it appears that a time series analysis of VOCs during the dry and wet months may provide a better understanding of the degree and risk of pollution of the Mahaweli River water.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.gsd.2016.04.001
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84969760258&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84969760258&origin=inward
  DOI ID：10.1016/j.gsd.2016.04.001, eISSN：2352-801X, SCOPUS ID：84969760258, 共同研究・競争的資金等ID：44511249
• Pore network structure linked by X-ray CT to particle characteristics and transport parameters　　　　　　　　　　　　　　　
  Shoichiro Hamamoto; Per Moldrup; Ken Kawamoto; Toshihiro Sakaki; Taku Nishimura; Toshiko Komatsu
  SOILS AND FOUNDATIONS, 巻：56, 号：4, 開始ページ：676, 終了ページ：690, 2016年08月, ［査読有り］
  Mass transport in soils occurs through pore networks that are highly affected by basic physical properties such as the degree of compaction, and particle size and shape. In this study, micro-focus X-ray computed tomography (CT) was used to obtain information on the pore network structure at different compaction levels for repacked columns of sands and glass beads representing different size fractions and particle shapes. Mass transport parameters, including gas diffusion coefficient (D-p) and air permeability (k(a)) at variably saturated conditions, were measured on the same columns using standard methods, and literature data on saturated hydraulic conductivity (K-sat) for the same materials were analyzed. A comparison of X-ray CT derived pore network structure and physical parameters showed that the round sands and glass beads exhibited larger pores, a higher pore coordination number, and a lower volumetric surface area than that of angular sands at the same particle size, resulting in higher K-sat as well as higher D-p and k(a) under relatively dry conditions. The X-ray CT derived the mean pore diameter (d), and the pore coordination number (C-n) for each material correlated well with key gas transport properties such as percolation thresholds and pore network connectivity. A predictive D-p model from wet to dry conditions based fully on X-ray CT derived parameters (d and C-n) was developed and showed good agreement with measured D-p for both round and angular sands. (C) 2016 The Japanese Geotechnical Society. Production and hosting by Elsevier B.V.
  JAPANESE GEOTECHNICAL SOC, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.sandf.2016.07.008
  DOI ID：10.1016/j.sandf.2016.07.008, ISSN：0038-0806, Web of Science ID：WOS:000384065100008
• Temperature change affected groundwater quality in a confined marine aquifer during long-term heating and cooling　　　　　　　　　　　　　　　
  Takeshi Saito; Shoichiro Hamamoto; Takashi Ueki; Satoshi Ohkubo; Per Moldrup; Ken Kawamoto; Toshiko Komatsu
  WATER RESEARCH, 巻：94, 開始ページ：120, 終了ページ：127, 2016年05月, ［査読有り］
  Global warming and urbanization together with development of subsurface infrastructures (e.g. subways, shopping complexes, sewage systems, and Ground Source Heat Pump (GSHP) systems) will likely cause a rapid increase in the temperature of relatively shallow groundwater reservoirs (subsurface thermal pollution). However, potential effects of a subsurface temperature change on groundwater quality due to changed physical, chemical, and microbial processes have received little attention. We therefore investigated changes in 34 groundwater quality parameters during a 13-month enhanced heating period, followed by 14 months of natural or enhanced cooling in a confined marine aquifer at around 17 m depth on the Saitama University campus, Japan. A full-scale GSHP test facility consisting of a 50 m deep U-tube for circulating the heat-carrying fluid and four monitoring wells at 1, 2, 5, and 10 m from the U-tube were installed, and groundwater quality was monitored every 1-2 weeks. Rapid changes in the groundwater level in the area, especially during the summer, prevented accurate analyses of temperature effects using a single-well time series. Instead, Dual-Well Analysis (DWA) was applied, comparing variations in subsurface temperature and groundwater chemical concentrations between the thermally-disturbed well and a non-affected reference well. Using the 1 m distant well (temperature increase up to 7 degrees C) and the 10 m distant well (non-temperature-affected), the DWA showed an approximately linear relationships for eight components (B, Si, Li, dissolved organic carbon (DOC), Mg2+, NH4+, Na+, and K+) during the combined 27 months of heating and cooling, suggesting changes in concentration between 4% and 31% for a temperature change of 7 degrees C. (C) 2016 Elsevier Ltd. All rights reserved.
  PERGAMON-ELSEVIER SCIENCE LTD, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.watres.2016.01.043
  DOI ID：10.1016/j.watres.2016.01.043, ISSN：0043-1354, Web of Science ID：WOS:000374360900012
• Temperature effects on solute diffusion and adsorption in differently compacted kaolin clay　　　　　　　　　　　　　　　
  Ei Ei Mon; Shoichiro Hamamoto; Ken Kawamoto; Toshiko Komatsu; Per Moldrup
  ENVIRONMENTAL EARTH SCIENCES, 巻：75, 号：7, 2016年04月, ［査読有り］
  Effects of soil temperature on the solute diffusion process in soils are important since subsurface temperature variation affects solute transport such as a fertilizer movement, leaching of salt, and pollutant movement to groundwater aquifers. However, the temperature dependency on the solute diffusion process in soils has been poorly understood and rarely documented. In this study, solute diffusion experiments as well as equilibrium adsorption experiments using pure kaolin clay were conducted under different temperature conditions. The experiments of K+ adsorption on kaolin clay showed more enhanced adsorption of K+ at elevated temperature likely because surface charge characteristics were affected at different temperature conditions for the kaolin clay. The temperature dependent solute diffusion showed that the solute diffusion coefficient at 40 degrees C was around two times higher than that at 6 degrees C for Cl- and K+. Overall, Arrhenius equation describing temperature dependent solute diffusion was applicable for both ions in samples at different bulk densities. At 40 degrees C, the liquid-phase impedance factor decreased, while liquid-phase pore-network tortuosity increased, suggesting changes in chemical surface activity towards the solute or pore structure changes of the clay fabric at the elevated temperature.
  SPRINGER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s12665-016-5358-2
  DOI ID：10.1007/s12665-016-5358-2, ISSN：1866-6280, eISSN：1866-6299, Web of Science ID：WOS:000373635400021
• Adsorption of Cd²⁺ and Pb²⁺ onto coconut shell biochar and biochar-mixed soil　　　　　　　　　　　　　　　
  G. N. Paranavithana; K. Kawamoto; Y. Inoue; T. Saito; M. Vithanage; C. S. Kalpage; G. B.B. Herath
  Environmental Earth Sciences, 巻：75, 号：6, 2016年03月
  Permeable reactive barrier (PRB) systems containing effective and low-cost adsorbents for heavy metals are expected to function as in situ treatment methods for leachate from waste landfills and contaminated groundwater surrounding the landfills in developing countries. This study was conducted to characterize the adsorption of Cd2+ and Pb2+ onto coconut shell biochar (fine granules), a local soil from Sri Lanka (Entisol), and a biochar-mixed soil (1:1 mixture of biochar and soil) as potential adsorbents for PRB systems. Batch experiments were carried out to investigate the effects of solution pH, contact time, initial ion concentration, and competitive ions on the Cd2+ and Pb2+ adsorption. Results showed that the adsorption kinetics of Cd2+ and Pb2+ onto all adsorbents were well described by the pseudo second order kinetics model and that adsorption isotherms followed the Langmuir model. In the range of pH ≥3, the initial solution pH had a minor effect on efficiency of metal removal and the removal of metals mostly exceeded 80 % for all adsorbents. Measured maximum adsorptions onto soil and biochar-mixed soil were 30.1 mmol/g for Cd2+ and 44.8–46.7 mmol/g for Pb2+. These adsorption capacities are similar to or higher than the values of biosorbents tested for wastewater treatment in previous studies, suggesting our tested materials would be useful as adsorbents of Cd2+ and Pb2+ in PRB systems. Additional analysis by scanning electron microscopy linked with energy dispersive X-ray revealed that both Cd2+ and Pb2+ exhibited high adsorption affinity towards soil particles while adsorbing randomly to biochar granules.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s12665-015-5167-z
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84960976929&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84960976929&origin=inward
  DOI ID：10.1007/s12665-015-5167-z, ISSN：1866-6280, eISSN：1866-6299, SCOPUS ID：84960976929
• Soil-water repellency characteristic curves for soil profiles with organic carbon gradients　　　　　　　　　　　　　　　
  Nadeeka Senani Wijewardana; Karin Mueller; Per Moldrup; Brent Clothier; Toshiko Komatsu; Syuntaro Hiradate; Lis Wollesen de Jonge; Ken Kawamoto
  GEODERMA, 巻：264, 開始ページ：150, 終了ページ：159, 2016年02月, ［査読有り］, ［最終著者］
  Soil water repellency (SWR) of soils is a property with significant consequences for agricultural water management, water infiltration, contaminant transport, and for soil erosion. It is caused by the presence of hydrophobic agents on mineral grain surfaces. Soils were samples in different depths at three forest sites in Japan and three pasture sites in New Zealand, covering soil organic carbon (SOC) contents between 1 and 26%. The SWR was measured over a range of water contents by three common methods; the water drop penetration time (WDPT) test, the molarity of an ethanol droplet (MED) method, and the sessile drop method (SDM). The aim to (i) compare the methods, (ii) characterize the soil-water repellency characteristic curves (SWRCC) being SWR as a function of the volumetric soil-water content (theta) or matric potential (psi), and (iii) find relationships between SWRCC parameters and SOC content. The WDPT, MED, and SDM generally agreed well in predicting the theta Orange where SWR occurred, and there was close agreement between SWR results determined by average MED and SDM at similar theta. Generally, SWR was only found within the top 20 cm of the soil profiles. Six SWR parameters were introduced: (i) the area under the curve (S-WR(theta)); (ii) theta at the maximum SWR (theta(WR-max)), (iii) theta where SWR ceased (theta(non-WR)), (iv) the maximum SWR (CA(i-max)) (v) pF at the maximum SWR (pF(WR-max)) and (vi) pF where SWR ceased (pF(non-WR)) The relationship between the first three parameters and SOC content were best described with Langmuir type equations (r(2) of 0.5-0.7), while the other three parameters changed linearly with SOC contents. (C) 2015 Elsevier B.V. All rights reserved.
  ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.geoderma.2015.10.020
  DOI ID：10.1016/j.geoderma.2015.10.020, ISSN：0016-7061, eISSN：1872-6259, Web of Science ID：WOS:000366776100016, 共同研究・競争的資金等ID：44511241
• Transport properties and pore-network structure in variably-saturated Sphagnum peat soil　　　　　　　　　　　　　　　
  S. Hamamoto; S. H. Dissanayaka; K. Kawamoto; O. Nagata; T. Komtatsu; P. Moldrup
  EUROPEAN JOURNAL OF SOIL SCIENCE, 巻：67, 号：1, 開始ページ：121, 終了ページ：131, 2016年01月, ［査読有り］
  Gas and water transport in peat soil are of increasing interest because of their potentially large environmental and climatic effects under different types of land use. In this research, the water retention curve (WRC), gas diffusion coefficient (D-g) and air and water permeabilities (k(a) and k(w)) of layers in peat soil from two profiles were measured under different moisture conditions. A two-region Archie's Law (2RAL)-type model was applied successfully to the four properties; the reference point was taken at -9.8kPa of soil-water matric potential where volume shrinkage typically started to occur. For WRC in the very decomposed peat soil, the 2RAL saturation exponents (n) obtained for both the wetter (n(w)) and drier regions (n(d)) were smaller than those for the less decomposed peat. For D-g, the saturation exponent in the wetter region was larger than that in the drier one for all layers, which indicated enhanced blocking effects of water on gas diffusion in the wetter region. For the peat layers within each soil, there was a linear relation between saturation exponents in the drier region for k(a) and D-g. The larger saturation exponent of the wetter region for k(w) in peat than in sand suggests a need for specific hydraulic functions for peat soil. The 2RAL model for D-g agreed well with measured data, and performed better than existing unimodal models. To facilitate use of the 2RAL for D-g, we developed a simple predictive expression for D-g at the reference point. The pore-network tortuosity factor and equivalent pore diameter for gas transport confirmed very different pore structure and mass transport behaviour for peat soil and uniform sand.
  WILEY-BLACKWELL, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/ejss.12312
  DOI ID：10.1111/ejss.12312, ISSN：1351-0754, eISSN：1365-2389, ORCID：38310240, Web of Science ID：WOS:000368079600015
• Characterization of water repellency for hydrophobized grains with different geometries and sizes　　　　　　　　　　　　　　　
  N. Senani Wijewardana; Ken Kawamoto; Per Moldrup; Toshiko Komatsu; L. Chandana Kurukulasuriya; Nadeej H. Priyankara
  ENVIRONMENTAL EARTH SCIENCES, 巻：74, 号：7, 開始ページ：5525, 終了ページ：5539, 2015年10月, ［査読有り］
  Capillary barrier cover systems (CBCSs) are useful and low-cost earthen cover systems for preventing water infiltration and controlling seepage at solid waste landfills. A possible technique to enhance the impermeable properties of CBCSs is to make water repellent grains by mixing the earthen cover material with a hydrophobic agent (HA). In this study, six different grains with different geometries and sizes were used to prepare dry hydrophobized grains by mixing with different contents of oleic acid as a HA. Wet hydrophobized grains were prepared by adjusting the water content (theta(g); kg kg(-1)) of dry hydrophobized grains. To characterize the water repellency (WR) of dry and wet hydrophobized grains, initial solidwater contact angles (alpha(i)) were measured using the sessile drop method (SDM). Based on SDM results from the aiHA content and alpha(i)-theta(g) curves, useful WR indices were introduced as "Area_(dry)'' and "Area_(wet)'' (areas under the alpha(i)-HA content and alpha(i)-theta(g) curves, respectively), "HA_(zica)'' and "theta(g)_(zica)'' (maximum HA content and theta(g) at which WR disappears, respectively), and "alpha(i,peak)'' and "HA_alpha(i,peak)'' (peak alpha(i) in the alpha(i)-HA content curve and corresponding HA content to alpha(i),(peak), respectively). Pearson correlation analysis was performed to identify correlations between proposed WR indices and basic grain properties. Results showed that WR indices correlated well to d(50) and coefficient of uniformity (C-u) and regression equations for WR indices were obtained as functions of d(50) and C-u (r(2) > 0.7).
  SPRINGER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s12665-015-4565-6
  DOI ID：10.1007/s12665-015-4565-6, ISSN：1866-6280, eISSN：1866-6299, Web of Science ID：WOS:000362016100006
• The Water-Induced Linear Reduction Gas Diffusivity Model Extended to Three Pore Regions　　　　　　　　　　　　　　　
  T. K. K. Chamindu Deepagoda; Lis Wollesen de Jonge; Ken Kawamoto; Toshiko Komatsu; Per Moldrup
  VADOSE ZONE JOURNAL, 巻：14, 号：10, 2015年10月, ［査読有り］
  Characterization of soil functional pore structure is an essential prerequisite to understand key gas transport processes in variably saturated soils in relation to soil ecosystems, climate, and environmental services. In this study, the water-induced linear reduction (WLR) soil gas diffusivity model originally developed for sieved, repacked soil was extended to two simple, linear regions to characterize gas diffusion and functional pore-network structure also in intact, structured soil systems. Based on the measurements in soils with markedly different pore regions, we showed that the two linear regions can denote a percolation threshold where soil gas diffusion ceases due to interconnected water films, preferential gas diffusion in fracture networks (e.g., fractured limestone), and intra-aggregate or intramatrix gas diffusion. From measured or three-region WLR (3WLR) modeled gas diffusivity, we derived a simple pore connectivity index, Cip (ranging from 0 to 1), that showed a linear behavior with air-filled porosity (epsilon) for sieved, repacked soils ranging from 6 to 54% clay. We suggest that deviation from this Cip. e line is a direct measure of soil structure. The new 3WLR model could accurately describe gas diffusivity from moist to dry conditions across differently structured porous media, including narrow soil size fractions, perforated plastic blocks, fractured limestone, peaty soils, aggregated volcanic ash soils, and particulate substrates for Earth-or space-based applications. The new Cip function provided distinct soil structural fingerprints from moist to dry conditions for all porous media. We further used the 3WLR and Cip analyses to discuss the decreasing trend in gas diffusion percolation threshold with soil compaction.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/vzj2015.04.0051
  DOI ID：10.2136/vzj2015.04.0051, ISSN：1539-1663, Web of Science ID：WOS:000367225300003
• Geotechnical Properties of Kanto Alluvial Soils based on Geochemical Survey　　　　　　　　　　　　　　　
  Shoichiro Hamamoto; Ken Kawamoto; Takato Takemura; Katsumi Kimura; Toshiko Komatsu; Masanobu Oda
  GSTF Journal of Geological Sciences, 巻：2, 号：1, 開始ページ：1, 終了ページ：7, 2015年07月, ［査読有り］
  Global Science {\&} Technology Forum Pte Ltd., 研究論文（学術雑誌）
  DOI：https://doi.org/10.5176/2335-6774_2.1.18
  DOI ID：10.5176/2335-6774_2.1.18, ORCID：35962418
• Temperature effects on geotechnical and hydraulic properties of bentonite hydrated with inorganic salt solutions　　　　　　　　　　　　　　　
  H. M.A. Rashid; K. Kawamoto; T. Saito; T. Komatsu; Y. Inoue; P. Moldrup
  International Journal of GEOMATE, 巻：8, 号：1, 開始ページ：1172, 終了ページ：1179, 2015年, ［査読有り］
  This study investigated the combined effect of temperature and single-species salt solutions on geotechnical properties (swell index and liquid limit) and hydraulic conductivity of bentonite applying different cation types, concentrations, and temperatures. Results showed that both the swell index and the liquid limit decreased with an increase in salt concentration irrespective of the type of cation. Monovalent cations showed higher values of the swell index and the liquid limit compared to divalent cations. In general, the swell index of bentonite increased whereas the liquid limit decreased with increasing temperature for all cation types and concentrations. Significant and high correlations were found between swell index and liquid limit of bentonite at all three temperatures. Hydraulic conductivity of bentonite was found to increase with increasing temperature. No significant change in hydraulic conductivity with time was observed for all concentrations and cation types, and, overall, concentration and valance of cations had little effect on the hydraulic conductivity of bentonite.
  GEOMATE International Society, 英語, 研究論文（学術雑誌）
  ISSN：2186-2982, SCOPUS ID：84930268026
• Modeling gravity effects on water retention and gas transport characteristics in plant growth substrates　　　　　　　　　　　　　　　
  T. K. K. Chamindu Deepagoda; Scott B. Jones; Markus Tuller; Lis Wollesen de Jonge; Ken Kawamoto; Toshiko Komatsu; Per Moldrup
  ADVANCES IN SPACE RESEARCH, 巻：54, 号：4, 開始ページ：797, 終了ページ：808, 2014年08月, ［査読有り］
  Growing plants to facilitate life in outer space, for example on the International Space Station (ISS) or at planned deep-space human outposts on the Moon or Mars, has received much attention with regard to NASA's advanced life support system research. With the objective of in situ resource utilization to conserve energy and to limit transport costs, native materials mined on Moon or Mars are of primary interest for plant growth media in a future outpost, while terrestrial porous substrates with optimal growth media characteristics will be useful for onboard plant growth during space missions. Due to limited experimental opportunities and prohibitive costs, liquid and gas behavior in porous substrates under reduced gravity conditions has been less studied and hence remains poorly understood. Based on ground-based measurements, this study examined water retention, oxygen diffusivity and air permeability characteristics of six plant growth substrates for potential applications in space, including two terrestrial analogs for lunar and Martian soils and four particulate substrates widely used in reduced gravity experiments. To simulate reduced gravity water characteristics, the predictions for ground-based measurements (1 - g) were scaled to two reduced gravity conditions, Martian gravity (0.38 - g) and lunar gravity (0.16 - g), following the observations in previous reduced gravity studies. We described the observed gas diffusivity with a recently developed model combined with a new approach that estimates the gas percolation threshold based on the pore size distribution. The model successfully captured measured data for all investigated media and demonstrated the implications of the poorly-understood shift in gas percolation threshold with improved gas percolation in reduced gravity. Finally, using a substrate-structure parameter related to the gaseous phase, we adequately described the air permeability under reduced gravity conditions. (C) 2014 COSPAR. Published by Elsevier Ltd. All rights reserved.
  ELSEVIER SCI LTD, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.asr.2014.04.018
  DOI ID：10.1016/j.asr.2014.04.018, ISSN：0273-1177, eISSN：1879-1948, Web of Science ID：WOS:000339692800022
• Simultaneous Loss of Soil Biodiversity and Functions along a Copper Contamination Gradient: When Soil Goes to Sleep　　　　　　　　　　　　　　　
  Muhammad Naveed; Per Moldrup; Emmanuel Arthur; Martin Holmstrup; Mogens Nicolaisen; Markus Tuller; Lasantha Herath; Shoichiro Hamamoto; Ken Kawamoto; Toshiko Komatsu; Hans-Joerg Vogel; Lis Wollesen de Jonge
  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, 巻：78, 号：4, 開始ページ：1239, 終了ページ：1250, 2014年07月, ［査読有り］
  The impact of biodiversity loss on soil functions is well established via laboratory experiments that generally consider soil biota groups in isolation from each other, a condition rarely present in field soils. As a result, our knowledge about anthropogenic-induced changes in biodiversity and associated soil functions is limited. We quantified an array of soil biological constituents (plants, earthworms, nematodes, bacteria, and fungi) to explore their interactions and to characterize their influence on various soil functions (habitat for soil organisms, air and water regulation, and recycling of nutrients and organic waste) along a legacy Cu pollution gradient. Increasing Cu concentrations had a detrimental impact on both plant growth and species richness. Belowground soil biota showed similar responses, with their sensitivity to elevated Cu concentrations decreasing in the order: earthworms > bacteria > nematodes > fungi. The observed loss of soil biota adversely affected natural soil bioturbation, aggregate formation and stabilization, and decomposition and mineralization processes and therefore resulted in compacted soil with narrow pore size distributions and overall smaller pores, restricted air and water storage and flow, and impeded C, N, and P cycling. The simultaneous evolution of soil biodiversity and functions along the Cu gradient emphasized the key role of soil life in controlling ecosystem services. Furthermore, results indicated that different soil biodiversity and functional indicators started to decline (10% loss) within a Cu concentration range of 110 to 800 mg total Cu kg(-1).
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/sssaj2014.02.0052
  DOI ID：10.2136/sssaj2014.02.0052, ISSN：0361-5995, eISSN：1435-0661, Web of Science ID：WOS:000343163800011
• A new method to quantify how water repellency compromises soils' filtering function　　　　　　　　　　　　　　　
  K. Mueller; M. Deurer; K. Kawamoto; T. Kuroda; S. Subedi; S. Hiradate; T. Komatsu; B. E. Clothier
  EUROPEAN JOURNAL OF SOIL SCIENCE, 巻：65, 号：3, 開始ページ：348, 終了ページ：359, 2014年05月, ［査読有り］
  Soil water repellency (SWR) is known to lead to preferential flow and to degrade the soil's filtering efficiency. However, no method is available to quantify directly how SWR affects the transport of reactive solutes. We propose a new method for conducting solute transport experiments in water-repellent soils. It involves sequentially applying two liquids, one water, the other a reference fully wetting liquid, namely aqueous ethanol, to the same intact soil core with air-drying between liquids. We applied this approach to quantify the impact of SWR on the filtering of the herbicide 2,4-Dichlorophenoxyacetic acid (2,4-D) in two Andosols. In batch experiments conducted prior to the transport experiments, 2,4-D sorption was not influenced by aqueous ethanol for one soil. However, sorption in the second soil followed the co-solvency theory, which predicts decreasing sorption with increasing solvent fractions. Thus, sorption experiments are necessary to complement our new method. Breakthrough curves were characterized by preferential flow with large initial concentrations, tailing and a long prevalence of solutes remaining in the soil. In the soil in which 2,4-D sorption was unaffected by aqueous ethanol, SWR increased 2,4-D losses by four and 50 times in the first 5-mm outflow compared with the 2,4-D losses with water. After 50-mm outflow, the 2,4-D losses were similar for one core, but in the other core they were still about four times greater with water than with aqueous ethanol. This method to quantify the reduction of the soil's filtering efficiency by SWR is needed for assessing the increased risk of groundwater contamination by solutes exogenously applied to water-repellent soils.
  WILEY-BLACKWELL, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/ejss.12136
  DOI ID：10.1111/ejss.12136, ISSN：1351-0754, eISSN：1365-2389, Web of Science ID：WOS:000335445800003
• Adsorption of Cd(II) and Pb(II) onto humic acid-treated coconut (cocos nucifera) husk　　　　　　　　　　　　　　　
  B. G.N. Sewwandi; Meththika Vithanage; S. S.R.M.D.H.R. Wijesekara; M. I.M. Mowjood; Shoichiro Hamamoto; Ken Kawamoto
  Journal of Hazardous, Toxic, and Radioactive Waste, 巻：18, 号：2, 2014年, ［最終著者］
  This study was conducted to characterize the adsorption of Cd2+ and Pb2+ by raw coconut husk (RCH) and humic acid-treated coconut husk (HACH). Grounded and sieved coconut husk (CH) from Sri Lanka was treated with humic acid to use as the adsorbent in laboratory experiments. Capacities of HACH and RCH for adsorption of Cd2+ and Pb2+ at different pH, ionic strengths, initial metal concentrations, and contact times between adsorbent and adsorbate were measured. The effects of binary metal solution, anions, and cations on adsorptions of Cd2+ and Pb2+ by treated and nontreated CH in batch experiments were also examined. The surface characteristics of HACH and RCH were investigated by scanning electron micrography (SEM), X-ray energy dispersion analysis (EDAX), methylene blue (MB), and the Brunauer, Emmett, and Teller (BET) methods to explain the results. Results showed that adsorption of Cd2+ and Pb2+ ions by HACH was independent of pH and ionic strength. The maximum adsorption capacities of Cd2+ and Pb2+ of HACH were 47.28 and 66.26 mg g-1 and were greater than 24.24 and 21.21 mg g-1 for RCH. The adsorption of both Cd2+ and Pb2+ onto HACH was a chemical sorption, and Pb2+ adsorption needed a longer reaction time than Cd2+ adsorption. The adsorption reaction rates of Cd2+ and Pb2+ of HACH were 0.056 and 3.17 mg g-1 min-1. Some anions and cations affected the adsorption of Cd2+ and Pb2+ onto HACH. Based on the results from adsorption tests under different conditions, RCH and HACH are effective for individual removal of Cd2+ and Pb2+ from aqueous solutions. However, humic acid treatment effectively removes metal ions from single metal solutions, although the removal of metal ions in the presence of coexisting ions and other anions and cations could be retarded. © 2014 American Society of Civil Engineers.
  American Society of Civil Engineers (ASCE), 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1061/(ASCE)HZ.2153-5515.0000196
  DOI ID：10.1061/(ASCE)HZ.2153-5515.0000196, ISSN：2153-5515, SCOPUS ID：84896290879, 共同研究・競争的資金等ID：44511249
• Contact Angles of Water-repellent Porous Media Inferred by Tensiometer- TDR Probe Measurement Under Controlled Wetting and Drying Cycles　　　　　　　　　　　　　　　
  Shaphal Subedi; Ken Kawamoto; Toshiko Komatsu; Per Moldrup; Lis Wollesen de Jonge; Karin Mueller; Brent Clothier
  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, 巻：77, 号：6, 開始ページ：1944, 終了ページ：1954, 2013年11月, ［査読有り］
  The time dependency of water repellency (WR) in hydrophobic porous media plays a crucial role for water infiltration processes after rainfall and for the long-term performance of capillary barrier systems. The contact angle (CA) of hydrophobic media normally decreases with continuous contact with water, eventually allowing water imbibition. However, the effect of the reduction in CA with soil-water contact time on the water retention function of hydrophobic media is not yet fully understood. In this study, water retention characteristics were measured using a hanging water column apparatus equipped with a mini-time domain reflectometry (TDR) coil probe under controlled wetting and drying in a water-repellent volcanic ash soil (VAS) and in sands coated with different hydrophobic agents. The contact angle (CA(-SWRC)) under imbibition was evaluated based on the inflection points on the water retention curves. For both water-repellent VAS and hydrophobized sand samples, the calculated CA(-SWRC) increased with increasing WR. This was determined from both the water drop penetration time and the initial contact angle (CA(i)) by the sessile drop method. Calculated CA(-SWRC) values ranged from 20 degrees to 48 degrees for the water-repellent VAS and from 40 degrees to 63 degrees for the hydrophobized sand. The CA reduction with contact time was quantified by relating CA(-SWRC) and CA(i). This gave a significant linear relationship for the hydrophobized sand [CA(-SWRC) = 0.40CA(i) + 11.3 (30 degrees < CA(i) < 120 degrees), R-2 = 0.66]. A large difference in water-filled pore distributions under controlled wetting and drying cycles was found on calculating the soil water capacity and pore size density as a function of water potential.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/sssaj2013.05.0203
  DOI ID：10.2136/sssaj2013.05.0203, ISSN：0361-5995, eISSN：1435-0661, Web of Science ID：WOS:000327024500005
• Mini tensiometer-time domain reflectometry coil probe for measuring soil water retention properties　　　　　　　　　　　　　　　
  Shaphal Subedi; Ken Kawamoto; Anurudda Kumara Karunarathna; Per Moldrup; Lis Wollesen De Jonge; Toshiko Komatsu
  Soil Science Society of America Journal, 巻：77, 号：5, 開始ページ：1517, 終了ページ：1528, 2013年09月, ［査読有り］
  Time domain reflectometry (TDR) is used widely for measuring soil-water content. New TDR coil probe technology facilitates the development of small, nondestructive probes for simultaneous measurement of soil-water content (θ) and soil-water potential (ψ). In this study we developed mini tensiome-ter-time domain reflectometry (T-TDR) coil probes, 6-mm wide and 32-mm long. The coil probes were calibrated against a conventional three-rod probe and were used for measuring θ for a aggregated volcanic ash soil (VAS) and a uniform sand. A commonly-used dielectric mixing model did not accurately describe the measured relation between the dielectric constant of the T-TDR coil probe (εcoil) and θ, and a new calibration model for εcoil (θ) was proposed instead. The new model assumes single-region behavior for sand and two-region behavior for aggregated VAS, when plotting the normalized dielectric constant of the coil probe (εcoil-εdry where εdry is the dielectric constant of the T-TDR coil probe for air-dried material) as a function of θ. The new calibration model accurately described the (εcoil-εdry)-θ relations measured by 7 T-TDR coil probes on both sand and VAS. Additionally, there was a good agreement between measured soil-water retention curves (ψ >
  -100 cm H2O) by the new T-TDR coil probes and independent measurements by the hanging water column method. © Soil Science Society of America, All rights reserved.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/sssaj2012.0106
  DOI ID：10.2136/sssaj2012.0106, ISSN：0361-5995, SCOPUS ID：84884873654
• Gas Diffusivity-Based Design and Characterization of Greenhouse Growth Substrates　　　　　　　　　　　　　　　
  T. K. K. Chamindu Deepagoda; Per Moldrup; Markus Tuller; Mette Pedersen; Jose Choc Chen Lopez; Lis Wollesen de Jonge; Ken Kawamoto; Toshiko Komatsu
  VADOSE ZONE JOURNAL, 巻：12, 号：3, 2013年08月, ［査読有り］
  Growing plants in containerized substrates has long been common practice in horticulture. Containerized plants (e.g., greenhouse tomatoes) have restricted access to essential growth resources such as oxygen, water, and nutrients. Since a wide range of inorganic and organic materials, and different combinations thereof, are commonly used as growth media, detailed and comparable physical characterization is key to identify the best performing media. In this study, five potential growth media and two mixtures thereof were characterized based on soil gas diffusivity (D-p/D-o, where D-p and D-o are gas diffusion coefficients in soil air and free air, respectively) and an operationally defined critical window of diffusivity (CWD) representing the interval of air-filled porosity between critical air filled porosity where D-p/D-o approximate to 0.02 and interaggregate porosity. The D-p measurements were conducted with 100-cm(3) samples from wet to complete dry conditions achieved by stepwise air drying and equilibration of initially water-saturated samples. A previously developed inactive pore and density-corrected (IPDC) model was able to describe gas diffusivities for media with distinct inactive pore space in the interaggregate pore region reasonably well. An extended IPDC model was introduced for media exhibiting a second percolation threshold in the intra-aggregate pore region. The analysis revealed comparable CWD values for the majority of the investigated media. The results further highlighted the importance of other major aspects (physical, chemical, and biological) of growth media characterization for optimal growth media design. A simple approach toward designing a gas diffusivity mixing model is presented to assist with selection of optimal mixing ratios of growth media with markedly different D-p/D-o behavior.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/vzj2013.03.0061
  DOI ID：10.2136/vzj2013.03.0061, ISSN：1539-1663, Web of Science ID：WOS:000323161600039
• Structure-Dependent Water-Induced Linear Reduction Model for Predicting Gas Diffusivity and Tortuosity in Repacked and Intact Soil　　　　　　　　　　　　　　　
  Per Moldrup; T. K. K. Chamindu Deepagoda; Shoichiro Hamamoto; Toshiko Komatsu; Ken Kawamoto; Dennis E. Rolston; Lis Wollesen de Jonge
  VADOSE ZONE JOURNAL, 巻：12, 号：3, 2013年08月, ［査読有り］
  The soil-gas diffusion is a primary driver of transport, reactions, emissions, and uptake of vadose zone gases, including oxygen, greenhouse gases, fumigants, and spilled volatile organics. The soil-gas diffusion coefficient, D-p, depends not only on soil moisture content, texture, and compaction but also on the local-scale variability of these. Different predictive models have been developed to estimate D-p in intact and repacked soil, but clear guidelines for model choice at a given soil state are lacking. In this study, the water-induced linear reduction (WLR) model for repacked soil is made adaptive for different soil structure conditions (repacked, intact) by introducing a media complexity factor (C-m) in the dry media term of the model. With C-m = 1, the new structure-dependent WLR (SWLR) model accurately predicted soil-gas diffusivity (D-p/D-o, where D-o is the gas diffusion coefficient in free air) in repacked soils containing between 0 and 54% clay. With C-m = 2.1, the SWLR model on average gave excellent predictions for 290 intact soils, performing well across soil depths, textures, and compactions (dry bulk densities). The SWLR model generally outperformed similar, simple D-p/D-o models also depending solely on total and air-filled porosity. With C-m = 3, the SWLR performed well as a lower-limit D-p/D-o model, which is useful in terms of predicting critical air-filled porosity for adequate soil aeration. Because the SWLR model distinguishes between and well represents both repacked and intact soil conditions, this model is recommended for use in simulations of gas diffusion and fate in the soil vadose zone, for example, as a key element in developing more accurate climate change models.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/vzj2013.01.0026
  DOI ID：10.2136/vzj2013.01.0026, ISSN：1539-1663, Web of Science ID：WOS:000323161600009
• Modeling Air Permeability in Variably Saturated Soil from Two Natural Clay Gradients　　　　　　　　　　　　　　　
  Chamindu T. K. K. Deepagoda; Emmanuel Arthur; Per Moldrup; Shoichiro Hamamoto; Ken Kawamoto; Toshiko Komatsu; Lis Wollesen de Jonge
  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, 巻：77, 号：2, 開始ページ：362, 終了ページ：371, 2013年03月, ［査読有り］
  Understanding soil-gas phase properties and processes is important for finding solutions to critical environmental problems such as greenhouse gas emissions and transport of gaseous-phase contaminants in soils. Soil-air permeability, k(a) (mu m(2)), is the key parameter governing advective gas movement in soil and is controlled by soil physical characteristics representing soil texture and structure. Models predicting k(a) as a function of air-filled porosity (epsilon) often use a reference-point measurement, for example, k(a), 1000 at epsilon(1000) (where the measurement is done at a suction of -1000 cm H2O). Using k(a) measurements from two Danish arable fields, each located on natural clay gradients, this study presents a pore tortuosity-disconnectivity analysis to characterize the soil-gas phase. The main objective of this study is to investigate the effect of soil-moisture condition, clay content, and other potential drivers of soil texture and structure on soil-gas phase characteristics based on a k(a)-based pore tortuosity parameter, X-a [= log(k(a)/k(a,1000))/log(epsilon/epsilon(,1000))]. Results showed that X-a did not vary significantly with soil matric potential (in the range of -10 to -1000 cm H2O), but the average X-a across moisture conditions showed a strong linear relation (R-2 = 0.74) to clay content. The X-a, further showed promising relations to specific surface area, Rosin-Rammler particle size distribution indices, alpha and beta (representing characteristic particle size and degree of sorting, respectively), and the Campbell water retention parameter, b. Considering clay as a main driver of soil-gas phase characteristics, we developed expressions linking clay content and k(a,1000) at epsilon(1000) and discussed the effect of clay content on general k(a)-epsilon behavior.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/sssaj2012.0300
  DOI ID：10.2136/sssaj2012.0300, ISSN：0361-5995, eISSN：1435-0661, Web of Science ID：WOS:000322827900003
• Correlating Gas Transport Parameters and X-Ray Computed Tomography Measurements in Porous Media　　　　　　　　　　　　　　　
  Muhammad Naveed; Shoichiro Hamamoto; Ken Kawamoto; Toshihiro Sakaki; Manabu Takahashi; Toshiko Komatsu; Per Moldrup; Mathieu Lamande; Dorthe Wildenschild; Masa Prodanovic; Lis Wollesen de Jonge
  SOIL SCIENCE, 巻：178, 号：2, 開始ページ：60, 終了ページ：68, 2013年02月, ［査読有り］
  Gas transport parameters and X-ray computed tomography (CT) measurements in porous medium under controlled and identical conditions provide a useful methodology for studying the relationships among them, ultimately leading to a better understanding of subsurface gaseous transport and other soil physical processes. The objective of this study was to characterize the relationships between gas transport parameters and soil-pore geometry revealed by X-ray CT. Sands of different shapes with a mean particle diameter (d(50)) ranging from 0.19 to 1.51 mm were used as porous media under both air-dried and partially saturated conditions. Gas transport parameters including gas dispersivity (alpha), diffusivity (D-P/D-0), and permeability (k(a)) were measured using a unified measurement system (UMS). The 3DMA-Rock computational package was used for analysis of three-dimensional CT data. A strong linear relationship was found between alpha and tortuosity calculated from gas transport parameters (T-UMS = root epsilon.D-O/D-P), indicating that gas dispersivity has a linear and inverse relationship with gas diffusivity. A linear relationship was also found between k(a) and d(50)/T-UMS(2), indicating a strong dependency of k(a) on mean particle size and direct correlation with gas diffusivity. Tortuosity (T-MFX) and equivalent pore diameter (d(eq.MFX)) analyzed from microfocus X-ray CT increased linearly with increasing d(50) for both Granusil and Accusand and further showing no effect of particle shape. The T-UMS values showed reasonably good agreement with T-MFX values. The k(a) showed a strong relationship when plotted against d(eq.MFX)/T-MFX(2), indicating its strong dependency on pore size distribution and tortuosity of pore space.
  LIPPINCOTT WILLIAMS & WILKINS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1097/SS.0b013e318288784c
  DOI ID：10.1097/SS.0b013e318288784c, ISSN：0038-075X, Web of Science ID：WOS:000316738500002
• 沖積粘性土の剪断剛性率とその堆積時環境依存性に関する研究-関東平野南部における事例-　　　　　　　　　　　　　　　
  竹村貴人; 小田匡寛; 濱本昌一郎; 川本健; 赤間友哉; 田井秀迪; 木村克己
  地学雑誌, 巻：122, 号：3, 開始ページ：472, 終了ページ：492, 2013年, ［査読有り］
  The effects of earthquakes in the Kanto district are strongly related to the three-dimensional distribution of the soil mechanical properties of Chuseki-so, which is the name given to incised-valley fills from the Late Pleistocene to the Holocene. To characterize the effects of the sedimentary depositional environment and sedimentary process of Chuseki-so on soil mechanical properties, PS logging test, physical-chemical test, consolidation test, cyclic tri-axial test, and bender element test were conducted on an undisturbed core sample. Based on the test results, we propose a method to estimate the elastic shear modulus of clay soil from conventional soil properties, and discuss the relationship between the sedimentary process of Chuseki-so and the three-dimensional distribution of soil mechanical properties. Through our investigation, we derived the following conclusions: (1) The delta front and inner bay deposits of the Kasukabe core in the Nakagawa Lowland comprise very soft clay and have a high water content and liquidity index; these characteristics are related to the sedimentary depositional environment such as water depth and salinity (ratio of marine diatoms in the sediment). (2) The proposed method can be used to estimate elastic shear moduli on the basis of water content, depth, and locality parameter; in particular, it can be used to evaluate very soft clay, the N value of which is less than 1, on the basis of water content, an easily measurable property. (3) Both bender element and PS logging tests show similar S-wave velocities, and elastic shear moduli measured using the respective tests, G₀^BE and G₀^PS, were also similar; therefore, elastic shear moduli can be determined through measurements using these two tests or estimations based on water content. (4) The method to determine the elastic shear modulus, G₀^TR, which is obtained using a cyclic test, is proposed based on the H-D model; G₀^TR btained correlates well with G₀^BE, even if though it is obtained by a different method. The proposed method can be used to determine elastic shear moduli with great accurac.
  Tokyo Geographical Society, 日本語
  DOI：https://doi.org/10.5026/jgeography.122.472
  DOI ID：10.5026/jgeography.122.472, ISSN：0022-135X, CiNii Articles ID：130003373649
• 脱水・吸水過程が不飽和砂質土の通気係数に与える影響　　　　　　　　　　　　　　　
  笹沼公美; 濱本昌一郎; 川本健; 榊利博; 小松 登志子
  土木学会論文集C, 巻：69, 号：3, 開始ページ：378, 終了ページ：385, 2013年, ［査読有り］
  土壌汚染サイトにおいて，汚染範囲を正確に把握し汚染除去工法の最適化を図る上で，吸引圧や飽和度とガス輸送特性の理解することは非常に重要である．本研究では異なる粒径・形状を有する砂試料を用い，乾湿履歴が土壌の通気係数に与える影響を調べた．その結果，同気相率条件で脱水過程の方が吸水過程よりも低い通気係数を示した．これは，ガスの通り道となる間隙の連続性が吸水過程に比べ，脱水過程で低いためと考えられる．通気係数の実測値にべき乗の予測モデル式を適用した結果，ガスの通り道の連結性を表すパラメータと水分特性曲線のモデルパラメータに相関性があることが明らかになった．粒径の違いによる影響は明確にはみられなかったが，粒子形状の違いが粒子間接点数ならびに通気に寄与する間隙の連結性に影響を与えることが示唆された．
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.2208/jscejge.69.378
  DOI ID：10.2208/jscejge.69.378, eISSN：2185-6516, CiNii Articles ID：130004559405
• 異なる水分条件を有する砂の熱特性：粒子の粒径・形状，および石英含有率の影響　　　　　　　　　　　　　　　
  鴨志田剛久; 濱本昌一郎; 川本健; 榊利博; 小松登志子
  土壌の物理性, 巻：11, 開始ページ：11, 終了ページ：16, 2013年, ［査読有り］
  粒径.形状の異なる砂試料を用いて異なる水分条件で熱特性を測定した.体積熱容量は,土粒子の粒径-形状及び石英含有率によらず,同体積含水率で比較した場合,試料間で顕著な差はみられなかった.乾燥領域では,粗い粒子形状の砂試料において平均粒径が大きいほど体積含水率の上昇にともなう熱伝導率の増加率が高くなる結果が得られた.一方湿潤領域での熱伝導率の増加率は,同種の試料であれば粒径によらずほぼ一定であり,同粒径の試料で比較すると石英含有率の高い試料ほど高くなる結果が得られた.本研究で得られた絶乾.飽和状態における熱伝導率の経験式を既存の熱伝導率予測モデルに考慮することで,熱伝導率の予測精度は改善された.
  土壌物理学会, 日本語
  DOI：https://doi.org/10.34467/jssoilphysics.124.0_11
  DOI ID：10.34467/jssoilphysics.124.0_11, ISSN：0387-6012, eISSN：2435-2497, CiNii Articles ID：130008072513, CiNii Books ID：AN00347581
• Soil Specific Surface Area and Non-Singularity of Soil-Water Retention at Low Saturations　　　　　　　　　　　　　　　
  Emmanuel Arthur; Markus Tuller; Per Moldrup; Augustus C. Resurreccion; Mercer S. Meding; Ken Kawamoto; Toshiko Komatsu; Lis Wollesen de Jonge
  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, 巻：77, 号：1, 開始ページ：43, 終了ページ：53, 2013年01月, ［査読有り］
  The dry end of the soil water characteristic (SWC) is important for modeling vapor flow dynamics and predicting soil properties such as specific surface area (SSA) and clay content (CL). Verification of new instrumentation for rapid measurement of the dry end of the SWC is relevant to avoid long equilibration times and potential for hydraulic decoupling. The objectives of this study were to measure both adsorption and desorption branches of the dry end of the SWC for 21 variably-textured Arizona soils using new, fully automated instrumentation (AquaSorp); apply the data to parameterize the Tuller and Or (TO) and new single-parameter non-singularity (SPN) models; and evaluate estimates of SSA from water sorption, ethylene glycol monoethyl ether (EGME), and N-2-BET methods. The AquaSorp successfully measured water sorption isotherms (similar to 140 data points) within a reasonably short time (1-3 d). The SPN model well described the distinct non-singularity between the adsorption and desorption branches, while the TO model captured the adsorption data reasonably well (<5% deviation from measurements), except for matric potentials below -200 MPa. The SSA derived from water sorption and the TO model were comparable to SSA(EGME) for all soils. The matric potential at "zero" water content was confirmed as the widely accepted value of around -800 MPa. A non-singularity coefficient based on water adsorption at monolayer coverage was positively correlated with CL. Obtained results show the potential of the AquaSorp to accurately measure the dry region of the SWC, providing a rapid determination of SSA.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/sssaj2012.0262
  DOI ID：10.2136/sssaj2012.0262, ISSN：0361-5995, Web of Science ID：WOS:000321750500005
• Prediction of the Soil Water Characteristic from Soil Particle Volume Fractions　　　　　　　　　　　　　　　
  Muhammad Naveed; Per Moldrup; Markus Tuller; T. P. A. Ferre; Ken Kawamoto; Toshiko Komatsu; Lis Wollesen de Jonge
  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, 巻：76, 号：6, 開始ページ：1946, 終了ページ：1956, 2012年11月, ［査読有り］
  Modeling water distribution and flow in partially saturated soils requires knowledge of the soil water characteristic (SWC). However, measurement of the SWC is challenging and time-consuming and, in some cases, not feasible. This study introduces two predictive models (F-w-model and A(w)-model) for the SWC, derived from readily available soil properties such as texture and bulk density. A total of 46 undisturbed soils from different horizons at 15 locations across Denmark were used for model evaluation. The F-w-model predicts the volumetric water content as a function of volumetric fines content (organic matter and clay). It performed reasonably well for the dry-end of SWC (above a pF value of 2.0; pF = log(vertical bar Psi vertical bar), where Psi is the matric potential in cm), but did not do as well closer to saturated conditions. The A(w)-model predicts the volumetric water content as a function of volumetric content of different particle size fractions (organic matter, clay, silt, and fine and coarse sands). The volumetric content of a particular soil particle size fraction was considered if it contributed to the pore size fraction still occupied with water at the given pF value. Hereby, the A(w)-model implicitly assumes that a given particle size fraction creates an analogue pore size fraction and further this pore size fraction filled with water is corresponding to a certain pF value according to the well-known capillary rise equation. The A(w)-model was found to be quite robust, and it performed exceptionally well for pF values ranging from 0.4 to 4.2 for different soil types. For prediction of the continuous SWC, it is recommended to parameterize the van Genuchten model based on the SWC data points predicted by the A(w)-model.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/sssaj2012.0124
  DOI ID：10.2136/sssaj2012.0124, ISSN：0361-5995, Web of Science ID：WOS:000312180100003
• Maxwell's Law Based Models for Liquid and Gas Phase Diffusivities in Variably-Saturated Soil　　　　　　　　　　　　　　　
  Shoichiro Hamamoto; Per Moldrup; Ken Kawamoto; Toshiko Komatsu
  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, 巻：76, 号：5, 開始ページ：1509, 終了ページ：1517, 2012年09月, ［査読有り］
  The gas diffusion coefficient (D-s,D-g) and solute diffusion coefficient (D-s,D-l) and their dependencies on fluid content (kappa) (equal to soil-air content theta for D-s,D-g and soil-water content epsilon for D-s,D-l) are controlling factors for gas and solute transport in variably saturated soils. In this study, we propose unified, predictive models for D-s,D-g(epsilon) and D-s,D-l(theta) based on modifying and extending the classical Maxwell model at fluid saturation with a fluid-induced reduction term including a percolation threshold (epsilon(th) for D-s,D-g and theta(th) for D-s,D-l). Different percolation threshold terms adopted from recent studies for gas (D-s,D-g) and solute (D-s,D-l) diffusion were applied. For gas diffusion, epsilon(th) was a function of bulk density (total porosity), while for solute diffusion theta(th) was best described by volumetric content of finer soil particles (clay and organic matter), FINESvol. The resulting LIquid and GAs diffusivity and tortuosity (LIGA) models were tested against D-s,D-g and D-s,D-l data for differently-textured soils and performed well against the measured data across soil types. A sensitivity analysis using the new Maxwell's Law based LIGA models implied that the liquid phase but not the gaseous-phase tortuosity was controlled by soil type. The analyses also suggested very different pathways and fluid-phase connectivity for gas and solute diffusion in unsaturated soil. In conclusion, the commonly applied strategy of using the same, soil-type-independent model for gas and solute diffusivity in analytical and numerical models for chemical transport and fate in variably-saturated soils appears invalid, except for highly sandy soils. The unified LIGA model with differing percolation thresholds for diffusion in the liquid and gaseous phases solves this problem.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/sssaj2012.0033
  DOI ID：10.2136/sssaj2012.0033, ISSN：0361-5995, Web of Science ID：WOS:000308806300001
• Diffusion Aspects of Designing Porous Growth Media for Earth and Space　　　　　　　　　　　　　　　
  Deepagoda T. K. K. Chamindu; Per Moldrup; Maria P. Jensen; Scott B. Jones; Lis Wollesen de Jonge; Per Schjonning; Kate Scow; Jan W. Hopmans; Dennis E. Rolston; Ken Kawamoto; Toshiko Komatsu
  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, 巻：76, 号：5, 開始ページ：1564, 終了ページ：1578, 2012年09月, ［査読有り］
  Growing plants in extraterrestrial environments, for example on a space station or in a future lunar or Martian outpost, is a challenge that has attracted increasing interest over the last few decades. Most of the essential plant needs for optimal growth (air, water, and nutrient supply, and mechanical support) are closely linked with the basic physical properties of the growth media. Diffusion is the main process whereby oxygen and nutrients are supplied to plant roots, and gas and solute diffusivity are the key parameters controlling the diffusive movement of oxygen and nutrients in the root zone. As one among several essential aspects of optimal porous media design for plant growth, this study presents a diffusion-based characterization of four commercial, aggregated growth media. To account for the observed large percolation threshold for gas diffusivity in the selected media, an inactive pore and density corrected (IPDC) model was developed and excellently described measured gas diffusivity in both inter-and intraaggregate pore regions. A strong relation (r(2) = 0.98) between percolation threshold for gas diffusivity and mean particle (aggregate) diameter was found and suggested to be used in future design models. Also, critical windows of diffusivity (CWD) was defined identifying the air content range where gas diffusivity (hence, oxygen supply) and solute diffusivity or the analogous electrical conductivity (hence, nutrient supply) are above pre-defined, critical minimum values. Assuming different critical values for gas diffusivity under terrestrial and Martian conditions, the four growth media were compared and it was found that one medium did not fulfill the pre-set criteria. Overall, the analyses suggested that particle (aggregate) sizes below 0.25 and above 5 mm should likely be avoided when designing safe plant growth media for space. The CWD concept was also applied to a natural volcanic ash soil (Nishi-Tokyo, Japan), and the natural soil was found competitive or better than the tested commercial growth media. This could bear large perspectives for Martian outpost missions, since NASA has found that Martian dust/soil mostly resembles volcanic ash soil among terrestrial materials.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/sssaj2011.0438
  DOI ID：10.2136/sssaj2011.0438, ISSN：0361-5995, eISSN：1435-0661, Web of Science ID：WOS:000308806300006
• Gas Dispersion in Granular Porous Media under Air-Dry and Wet Conditions　　　　　　　　　　　　　　　
  Muhammad Naveed; Shoichiro Hamamoto; Ken Kawamoto; Toshihiro Sakaki; Manabu Takahashi; Toshiko Komatsu; Lis Wollesen de Jonge; Mathieu Lamande; Per Moldrup
  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, 巻：76, 号：3, 開始ページ：845, 終了ページ：852, 2012年05月, ［査読有り］
  Subsurface gaseous-phase transport is governed by three gas transport parameters: the air permeability coefficient (k(a)), gas diffusion coefficient (D-p), and gas dispersion coefficient (D-H). Among these, D-H is the least understood due to hitherto limited research into the relationship between gas dispersion and soil physical characteristics. In this study, a series of advection dispersion experiments was performed on granular porous media to identify the effects of soil column dimensions (length and diameter), particle size and shape, dry bulk density, and moisture content on the magnitude of gas dispersion. Glass beads and various sands of different shapes (angular and rounded) with mean particle diameters (d(50)) ranging from 0.19 to 1.51 mm at both air-dry and variable moisture contents were used as granular porous media. Gas dispersion coefficients and gas dispersivities alpha = D-H/v, where v is the pore-gas velocity) were determined by fitting the advection-dispersion equation to the measured breakthrough curves. For all test conditions, D-H increased linearly with v. The test results showed that neither soil column length nor diameter had significant effect on gas dispersivity. Under air-dry conditions, higher gas dispersivities were observed for media with wider particle size distribution and higher dry bulk density. The minor effect of particle shape on gas dispersivity was found under both air-dry and wet conditions. Under wet conditions, the variations in gas dispersivity were mainly controlled by the air-filled porosity. An empirical model was also proposed for the prediction of gas dispersivity in granular, unsaturated porous media.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/sssaj2011.0314
  DOI ID：10.2136/sssaj2011.0314, ISSN：0361-5995, Web of Science ID：WOS:000304725100010
• Organic Matter Fraction Dependent Model for Predicting the Gas Diffusion Coefficient in Variably Saturated Soils　　　　　　　　　　　　　　　
  Shoichiro Hamamoto; Per Moldrup; Ken Kawamoto; Toshiko Komatsu
  VADOSE ZONE JOURNAL, 巻：11, 号：1, 2012年02月, ［査読有り］
  Gas diffusion is a dominant transport mechanism for climate and regulated gases in the vadose zone. Soil-gas diffusion is governed by the gas diffusion coefficient (D-p, m(2) s(-1)) which is highly dependent on soil texture, such as sand, silt, clay, and organic mater contents, as well as soil physical properties such as soil-air content (epsilon, m(3) m(-3)) or total porosity (Phi, m(3) m(-3)). Soil organic matter is a key contributor to the formation of the soil pore structure (i.e., total porosity and air-filled pore tortuosity), and it highly affects D-p behavior under variably saturated conditions. In this study, based on numerous D-p data sets across soil types including sands, loamy clay soils, volcanic ash soils, and organic soils, predictive D-p models incorporating a percolation threshold (epsilon th, m(3) m(-3)) and pore tortuosity factor (X') are proposed. The observed relations between either epsilon(th) or X' and either Phi or volumetric organic matter fraction (OMF, m(3) m(-3)) were embedded in the proposed D-p model. The proposed D-p models, coupled with predictive epsilon(th) and OMF models, performed well against the measured D-p data across soil types. Finally, a sensitivity analysis of the OMF in relation to the D-p and pore-network tortuosity (T) showed a reduction in D-p and increase in T with increasing OMF under the same epsilon conditions.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/vzj2011.0065
  DOI ID：10.2136/vzj2011.0065, ISSN：1539-1663, Web of Science ID：WOS:000304802500014
• Thermal Properties of Peaty Soils: Effects of Liquid-Phase Impedance Factor and Shrinkage　　　　　　　　　　　　　　　
  Shiromi Himalika Dissanayaka; Shoichiro Hamamoto; Ken Kawamoto; Toshiko Komatsu; Per Moldrup
  VADOSE ZONE JOURNAL, 巻：11, 号：1, 2012年02月, ［査読有り］
  Soil thermal conductivity (lambda) and heat capacity (C) control heat transport and the thermal environment for biogeophysical processes in the vadose zone. Accurate lambda and C predictions for peaty soils with high organic contents are particularly important for assessing emissions of greenhouse gases formed during microbial activity in wetlands. In this study, we measured the lambda and C at different soil-water matric potentials on undisturbed samples for three peaty soil profiles at the Hokkaido Bibai marsh in Japan, representing a total of 10 different soil horizons. The thermal properties under air-dried conditions, lambda(dry) and C-dry, were measured separately at changing volumetric solids contents (sigma). For each sample, volume shrinkage was observed to varying degrees during the drying process. Measured lambda and C increased linearly with increasing volumetric water content (theta). Applying the concept of a three-phase mixing model and incorporating the lambda-theta or C-theta and the lambda(dry)-sigma or C-dry-sigma relations, predictive lambda and C models were developed as functions of sigma and theta. The new mixing model is represented by lambda = lambda(dry) + f(lambda)theta lambda(w) and C = C-dry + f(C)theta C-w, where lambda(w) and C-w are the thermal conductivity and heat capacity of water, respectively, and f is an impedance factor that takes into account the liquid-phase tortuosity. The new mixing model predicted literature lambda-theta data on peaty and highly organic soils under variable saturation well. The probable ranges of lambda and C under variable saturation were proposed based on the sensitivity analysis.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/vzj2011.0092
  DOI ID：10.2136/vzj2011.0092, ISSN：1539-1663, Web of Science ID：WOS:000304802500025
• Characterizing Time-Dependent Contact Angles for Sands Hydrophobized with Oleic and Stearic Acids　　　　　　　　　　　　　　　
  Shaphal Subedi; Ken Kawamoto; Lakmal Jayarathna; Meththika Vithanage; Per Moldrup; Lis Wollesen de Jonge; Toshiko Komatsu
  VADOSE ZONE JOURNAL, 巻：11, 号：1, 2012年02月, ［査読有り］
  Capillary barriers (CBs) represent useful, low-cost systems for limiting water infiltration and controlling seepage at solid waste landfills in semiarid and arid regions. The application of CBs in wet regions can be problematic due to loss of water-impermeable properties under high-frequency precipitation. A potential solution is to alter soil grain surfaces to become water repellent by mixing or coating the soil cover material with hydrophobic agents (HAs). In this study, hydrophobic CBs comprised of sands mixed with environmentally friendly HAs (oleic acid [OA] and stearic acid [SA]) were studied. Water repellency (WR) characteristics for hydrophobized sand samples with different HA contents and representing different coating methods (mixing in and solvent aided) were measured. Initial contact angles (alpha(i)) for OA-coated samples sharply increased with increasing HA content and reached peak values of 97 to 101 degrees at 0.75 to 1.0 g HA kg(-1) sand, whereafter alpha(i) gradually decreased. Measured alpha(i) values for SA-coated samples increased sharply to 90 degrees and then gradually reached a maximum of 108 degrees at 6.0 g kg(-1) HA content. Each test sample exhibited a decrease in contact angle (alpha) withtime (t) and reached an apparent equilibrium after around 1200 s. The time dependence of alpha was expressed by an exponential function, alpha = alpha(i) exp (-At), where A is the coefficient of temporal change in WR (s(-1)). While the A values for the solvent-aided OA-coated samples were relatively constant (between 3 x 10(-4) and 6 x 10(-4) s(-1)), A values for the mixing-in OA-coated samples fluctuated. Generally, the solvent-aided coating method yielded less time dependency of alpha and higher WR persistence.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/vzj2011.0055
  DOI ID：10.2136/vzj2011.0055, ISSN：1539-1663, Web of Science ID：WOS:000304802500010
• Unified measurement system with suction control for measuring hysteresis in soil-gas transport parameters　　　　　　　　　　　　　　　
  Md Abdur Rouf; Shoichiro Hamamoto; Ken Kawamoto; Toshihiro Sakaki; Toshiko Komatsu; Per Moldrup
  WATER RESOURCES RESEARCH, 巻：48, 2012年02月, ［査読有り］
  A unified measurement system with suction control (UMS_SC) was developed for measuring soil water characteristics curves (SWCC) and gas transport parameters under alternating drying and wetting cycles. The new system consists of a diffusion chamber, sample ring, porous plate, tensiometer, moisture sensor, oxygen electrodes, and air pressure gauges. The SWCC and gas transport parameters [gas diffusion coefficient (D-p) and air permeability (k(a))] for two different porous materials, Toyoura sand and granulated slag, were simultaneously measured under drying and wetting cycles. The SWCC and gas transport parameters measured by UMS_SC were consistent with recent models and independently measured data on exactly the same materials using standard experimental setups from literature. For an applied water suction head of less than 50 cm and corresponding water saturation of around 0.3-0.5, the UMS_SC data documented hysteretic (nonsingular) behavior in both measured Dp and ka under repeated drying and wetting cycles. The hysteretic behavior was insignificant for water and air contents but large for both gas transport parameters when applying suction, and hysteretic effects were larger for air permeability than for gas diffusivity. Additionally, hysteresis in the percolation threshold (soil-air content where gas transport ceases due to interconnected water-filled pores) for both gas diffusion and air permeability was insignificant for both materials. These findings should be taken into account when developing models for diffusive and convective gas transport and their parameters in variably saturated porous media.
  AMER GEOPHYSICAL UNION, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1029/2011WR010615
  DOI ID：10.1029/2011WR010615, ISSN：0043-1397, Web of Science ID：WOS:000300231500001
• Variable Pore Connectivity Model Linking Gas Diffusivity and Air-Phase Tortuosity to Soil Matric Potential　　　　　　　　　　　　　　　
  T. K. K. Chamindu Deepagoda; Per Moldrup; Per Schjonning; Ken Kawamoto; Toshiko Komatsu; Lis Wollesen de Jonge
  VADOSE ZONE JOURNAL, 巻：11, 号：1, 2012年02月, ［査読有り］
  Soil-gas diffusivity (D-p/D-o) and its dependency on soil matric potential (psi) is important when taking regulative measures (based on accurate predictions) for climate gas emissions and also risk-mitigating measures (based on upper-limit predictions) of gaseous-phase contaminant emissions. Useful information on soil functional pore structure, e.g., pore network tortuosity and connectivity, can also be revealed from D-p/D-o-psi relations. Based on D-p/D-o measurements in a wide range of soil types across geographically remote vadose zone profiles, this study analyzed pore connectivity for the development of a variable pore connectivity factor, X, as a function of soil matric potential, expressed as pF (=log vertical bar-psi vertical bar), for pF values ranging from 1.0 to 3.5. The new model takes the form of X = X* (F/F*)(A) with F = 1 + pF(-1), where X* is the pore network tortuosity at reference F (F*) and A is a model parameter that accounts for water blockage. The X-pF relation can be linked to drained pore size to explain the lower probability of the larger but far fewer air-filled pores at lower pF effectively interconnecting and promoting gas diffusion. The model with X* = 2 and A = 0.5 proved promising for generalizing D-p/D-o predictions across soils of wide geographic contrast and yielded results comparable to those from widely used predictive models. The X-pF model additionally proved valuable for differentiating between soils (providing a unique soil structural fingerprint for each soil layer) and also between the inter-and intraaggregate pore regions of aggregated soils. We further suggest that the new model with parameter values of X* = 1.7 and A = 0 may be used for upper limit D-p/D-o predictions in risk assessments of, e.g., fluxes of toxic volatile organics from soil to indoor air at polluted soil sites.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/vzj2011.0096
  DOI ID：10.2136/vzj2011.0096, ISSN：1539-1663, Web of Science ID：WOS:000304802500026
• The pH Dependency of 2,4-Dichlorophenoxyacetic Acid Adsorption and Desorption in Andosol and Kaolinite　　　　　　　　　　　　　　　
  Ei Ei Mon; Anu Sharma; Ken Kawamoto; Shoichiro Hamamoto; Toshiko Komatsu; Syuntaro Hiradate; Per Moldrup
  SOIL SCIENCE, 巻：177, 号：1, 開始ページ：12, 終了ページ：21, 2012年01月, ［査読有り］
  Batch adsorption and consecutive desorption experiments were performed under different pH conditions to assess the pH dependency of 2,4-dichlorophenoxyacetic acid (2,4-D) adsorption and desorption in Andosol (having pH-dependent surface charge characteristics) and kaolinite. The adsorption-desorption isotherms for both Andosol and kaolinite were well fitted by the Freundlich isotherm model. Adsorption of 2,4-D onto Andosol increased markedly with decreasing pH and was higher than for kaolinite under the same pH condition. Hysteresis, expressing the nonsingularity of the desorption compared with the adsorption isotherm, was found at all concentrations and each pH for both Andosol and kaolinite. For Andosol, the fitted Freundlich parameters for desorption, K(f,d) and n(d), showed a negative, linear and a positive, exponential relationship, respectively, with pH. Higher hysteresis index (omega), expressing the degree of partial irreversibility of 2,4-D adsorption, was obtained under lower pH, indicating that less adsorbed 2,4-D was released back from the Andosol under acidic condition. The effect of pH on 2,4-D desorption from kaolinite was less pronounced as compared with Andosol. Combining the measured data in this study with previously reported data on 2,4-D adsorption-desorption in several types of soil including Andosols, the possible mobility of adsorbed 2,4-D in soil was evaluated. Results show that adsorbed 2,4-D in soils exhibiting a total adsorption percentage of less than 55% of the applied pesticide typically exhibited a greater potential to be mobile in the soil-water system. Opposite, a total adsorption percentage greater than 55% implied higher residual adsorption and a prolonged existence of adsorbed 2,4-D in the soils.
  LIPPINCOTT WILLIAMS & WILKINS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1097/SS.0b013e3182376ef3
  DOI ID：10.1097/SS.0b013e3182376ef3, ISSN：0038-075X, Web of Science ID：WOS:000299164400002
• Effects of dry bulk density and particle size fraction on gas transport parameters in variably saturated landfill cover soil　　　　　　　　　　　　　　　
  Praneeth Wickramarachchi; Ken Kawamoto; Shoichiro Hamamoto; Masanao Nagamori; Per Moldrup; Toshiko Komatsu
  WASTE MANAGEMENT, 巻：31, 号：12, 開始ページ：2464, 終了ページ：2472, 2011年12月, ［査読有り］
  Landfill sites are emerging in climate change scenarios as a significant source of greenhouse gases. The compacted final soil cover at landfill sites plays a vital role for the emission, fate and transport of landfill gases. This study investigated the effects of dry bulk density, rho(b), and particle size fraction on the main soil-gas transport parameters - soil-gas diffusivity (D(p)/D(o), ratio of gas diffusion coefficients in soil and free air) and air permeability (k(a)) - under variably-saturated moisture conditions. Soil samples were prepared by three different compaction methods (Standard and Modified Proctor compaction, and hand compaction) with resulting rho(b) values ranging from 1.40 to 2.10 g cm(-3). Results showed that D(p) and k(p) values for the '+gravel' fraction (<35 mm) became larger than for the '-gravel' fraction (<2 mm) under variably-saturated conditions for a given soil-air content (epsilon), likely due to enhanced gas diffusion and advection through less tortuous, large-pore networks. The effect of dry bulk density on D(p), and k(a) was most pronounced for the '+gravel' fraction. Normalized ratios were introduced for all soil-gas parameters: (i) for gas diffusivity D(p)/D(f), the ratio of measured D(p) to D(p) in total porosity (f), (ii) for air permeability k(a)/k(a,pF4.1), the ratio of measured k(a) to k(a), at 1235 kPa matric potential (=pF 4.1), and (iii) for soil-air content, the ratio of soil-air content (epsilon) to total porosity (f) (air saturation). Based on the normalized parameters, predictive power-law models for D(p)(epsilon/f) and k(a) (epsilon/f) models were developed based on a single parameter (water blockage factor M for D(p) and P for k(a)). The water blockage factors, M and P. were found to be linearly correlated to rho(b) values, and the effects of dry bulk density on D(p) and k(a) for both '+gravel' and '-gravel' fractions were well accounted for by the new models. (C) 2011 Elsevier Ltd. All rights reserved.
  PERGAMON-ELSEVIER SCIENCE LTD, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.wasman.2011.07.008
  DOI ID：10.1016/j.wasman.2011.07.008, ISSN：0956-053X, Web of Science ID：WOS:000297485700011
• Transport and deposition of suspended soil colloids in saturated sand columns　　　　　　　　　　　　　　　
  Anu Sharma; Ken Kawamoto; Per Moldrup; Lis Wollesen de Jonge; Toshiko Komatsu
  Journal of Hazardous, Toxic, and Radioactive Waste, 巻：15, 号：4, 開始ページ：275, 終了ページ：284, 2011年11月, ［査読有り］
  Understanding colloid mobilization, transport, and deposition in the subsurface is a prerequisite for predicting colloid-facilitated transport of strongly adsorbing contaminants and further developing remedial activities. This study investigated the transport behavior of soil-colloids extracted from a red-yellow soil from Okinawa, Japan. Different concentrations of suspended-soil colloids (with diameter <
  1 μm) were applied, at different flow velocities and pH conditions, to 10-cm long water-saturated columns repacked with either Narita (mean diameter D50=0.64 mm) or Toyoura (mean diameter D50=0.21 mm) sands. The transport and retention of colloids were studied by analyzing colloid effluent breakthrough curves (BTCs), particle size distribution in the effluent, and colloid deposition profiles within the column. The results showed a significant influence of flow velocity: Low flow velocity caused tailing of colloid BTCs with higher reversible entrapment and release of colloids than high flow velocity. The finer Toyoura sand retained more colloids than the coarser Narita sand at low pH conditions. The deposition profile and particle size distribution of colloids in the Toyoura sand clearly indicated a depth-dependent straining mechanism. By fitting colloid transport models (one-site and two-site models) to the colloid effluent breakthrough curves, transport and deposition of colloids in Narita sand at low pH were best described by a one-site attachment-detachment model, whereas colloid transport and deposition in Toyoura sand at low pH were better captured by a two-site attachment, detachment, and straining model. The coupled effects of solution chemistry, colloid sizes, and medium surface properties have a dominating role in particle-particle and particle-collector interactions in colloid transport and deposition. © 2011 American Society of Civil Engineers.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1061/(ASCE)HZ.1944-8376.0000060
  DOI ID：10.1061/(ASCE)HZ.1944-8376.0000060, ISSN：2153-5493, SCOPUS ID：80155137241
• Gas transport parameters for compacted reddish-brown soil in sri lankan landfill final cover　　　　　　　　　　　　　　　
  Praneeth Wickramarachchi; Kaushalya Ranasinghe; Shoichiro Hamamoto; Ken Kawamoto; Udeni P. Nawagamuwa; Per Moldrup; Toshiko Komatsu
  Journal of Hazardous, Toxic, and Radioactive Waste, 巻：15, 号：4, 開始ページ：285, 終了ページ：295, 2011年11月, ［査読有り］
  Gas exchange through the compacted final cover soil at landfill sites plays a vital role for emission, fate, and transport of toxic landfill gases. This study involved measuring the soil-gas diffusivity (Dp/Do, the ratio of gas diffusion coefficients in soil and free air) and air permeability (ka) for differently compacted soil samples (reddish-brown soil) from the final cover at the Maharagama landfill in Sri Lanka. The samples were prepared by either standard Proctor compaction or hand compaction to dry bulk densities of 1.60-1.94 g cm-3. Existing and modified models for predicting Dp/Do and ka were tested against the measured data. The simple, single-parameter Buckingham model predicted measured Dp/Do values across compaction levels equally well or better than a dry bulk density (DBD) dependent model and a soil-water retention (SWR) dependent model. The measured ka values for differently compacted samples were highly affected by the compaction level and the sample moisture preparation method. Also, for air permeability, a single-parameter Buckingham-type ka model was most accurate in predicting ka in the differently compacted soil samples. Equivalent air-filled pore diameters (the effective diameter of the drained pores active in leading air through the sample) for gas flow, deq, were calculated from the measured Dp/D0 and ka values. The deq increased with compaction level, suggesting that a very high compaction level creates well-connected macropores in the reduced total pore space of the cover soil. This is an important consideration when designing cover soils for optimally low water and high oxygen exchange while minimizing climate and toxic gas emissions from the waste layer to the atmosphere. © 2011 American Society of Civil Engineers.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1061/(ASCE)HZ.1944-8376.0000078
  DOI ID：10.1061/(ASCE)HZ.1944-8376.0000078, ISSN：2153-5493, SCOPUS ID：80155137236
• Transport and Deposition of Variably Charged Soil Colloids in Saturated Porous Media　　　　　　　　　　　　　　　
  Anu Sharma; Ken Kawamoto; Per Moldrup; Lis Wollesen de Jonge; Toshiko Komatsu
  VADOSE ZONE JOURNAL, 巻：10, 号：4, 開始ページ：1228, 終了ページ：1241, 2011年11月, ［査読有り］
  A series of column experiments was conducted to investigate the transport and deposition of variably charged colloids in saturated porous media. Soil colloids with diameters <1 mu m were extracted from a volcanic-ash soil from Nishi-Tokyo (referred to here as VAS colloids) and a red-yellow soil from Okinawa (RYS colloids) in Japan. The VAS colloids exhibited a negative surface charge with a high pH dependency, whereas the RYS colloids exhibited a negative surface charge with less pH dependency. The soil colloids were applied as colloidal suspensions to 10-cm-long saturated sand columns packed with either Narita sand (mean diameter = 0.64 mm) or Toyoura sand (mean diameter = 0.21 mm) at different flow rates, suspension concentrations, and pH conditions. Both sands exhibited a negative surface charge in the measured pH range, but the pH dependency was more pronounced for the Toyoura sand. Breakthrough curves and deposition profiles for soil colloids were strong functions of the hydrodynamics, solution pH, and surface charge of the colloids and sand grains. Greater deposition was typical for lower flow rates and lower pH. The deposition of VAS colloids in both sands under low-pH conditions exhibited depth-dependent retention, with high colloid deposition at the column inlet. The RYS colloids were mainly deposited uniformly along columns, and depth-dependent retention was observed only in Toyoura sand at low pH. Results suggest that decreasing solution pH enhanced surface charge neutralization of both soil colloids and sand grains, thereby increasing colloid deposition. This study emphasizes that the pH-dependent surface charge of both mobile colloids and receiving porous media needs more consideration in models for colloid and colloid-facilitated transport in soil.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/vzj2010.0161
  DOI ID：10.2136/vzj2010.0161, ISSN：1539-1663, Web of Science ID：WOS:000297377000009
• Extreme Compaction Effects on Gas Transport Parameters and Estimated Climate Gas Exchange for a Landfill Final Cover Soil　　　　　　　　　　　　　　　
  Shoichiro Hamamoto; Per Moldrup; Ken Kawamoto; Praneeth Nishadi Wickramarachchi; Masanao Nagamori; Toshiko Komatsu
  JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING, 巻：137, 号：7, 開始ページ：653, 終了ページ：662, 2011年07月, ［査読有り］
  Landfill sites have been implicated in greenhouse warming scenarios as a significant source of atmospheric methane. In this study, the effects of extreme compaction on the two main soil-gas transport parameters, the gas diffusion coefficient (D(p)) and the intrinsic air permeability (k(a)), and the cumulative methane oxidation rate in a landfill cover soil were investigated. Extremely compacted landfill cover soil exhibited negligible inactive soil-air contents for both D(p) and k(a). In addition, greater D(p) and k(a) were observed as compared with normal compacted soils at the same soil-air content (epsilon), likely because of reduced water-blockage effects under extreme compaction. These phenomena are not included in existing predictive models for D(p)(epsilon) and k(a)(epsilon). On the basis of the measured data, new predictive models for D(p)(epsilon) and k(a)(epsilon) were developed with model parameters (representing air-filled pore connectivity and water-blockage effects) expressed as functions of dry density (rho(b)). The developed D(p)(epsilon) and k(a)(epsilon) models together with soil-water retention data for soils at normal and extreme compaction (rho(b)=1.44 and 1.85 g cm(-3)) implied that extremely compacted soils will exhibit lower D(p) and k(a) at natural field-water content (-100 cm H(2)O of soil-water matric potential) because of much lower soil-air content. Numerical simulations of methane gas transport, including a first-order methane oxidation rate, were performed for differently compacted soils by using the new predictive D(p)(epsilon) model. Model results showed that compaction-induced difference in soil-air content at a given soil-water matric potential condition is likely the most important parameter governing methane oxidation rates in extremely compacted landfill cover soil.DOI: 10.1061/(ASCE)GT.1943-5606.0000459. (C) 2011 American Society of Civil Engineers.
  ASCE-AMER SOC CIVIL ENGINEERS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1061/(ASCE)GT.1943-5606.0000459
  DOI ID：10.1061/(ASCE)GT.1943-5606.0000459, ISSN：1090-0241, Web of Science ID：WOS:000292517800003
• Generalized Density-Corrected Model for Gas Diffusivity in Variably Saturated Soils　　　　　　　　　　　　　　　
  T. K. K. Chamindu Deepagoda; Per Moldrup; Per Schjonning; Ken Kawamoto; Toshiko Komatsu; Lis Wollesen de Jonge
  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, 巻：75, 号：4, 開始ページ：1315, 終了ページ：1329, 2011年07月, ［査読有り］
  Accurate predictions of the soil-gas diffusivity (D-p/D-o' where D-p is the soil-gas diffusion coefficient and D-o is the diffusion coefficient in free air) from easily measureable parameters like air-filled porosity (epsilon) and soil total porosity (phi) are valuable when predicting soil aeration and the emission of greenhouse gases and gaseous-phase contaminants from soils. Soil type (texture) and soil density (compaction) are two key factors controlling gas diffusivity in soils. We extended a recently presented density-corrected D-p(epsilon)/D-o model by letting both model parameters (alpha and beta) be interdependent and also functions of phi. The extension was based on literature measurements on Dutch and Danish soils ranging from sand to peat. The parameter alpha showed a promising linear relation to total porosity, while beta also varied with alpha following a weak linear relation. The thus generalized density-corrected (GDC) model gave improved predictions of diffusivity across a wide range of soil types and density levels when tested against two independent data sets (total of 280 undisturbed soils or soil layers) representing Danish soil profile data (0-8 m below the ground surface) and performed better than existing models. The GDC model was further extended to describe two-region (bimodal) soils and could describe and predict D-p/D-o well for both different soil aggregate size fractions and variably compacted volcanic ash soils. A possible use of the new GDC model is engineering applications such as the design of highly compacted landfill site caps.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/sssaj2010.0405
  DOI ID：10.2136/sssaj2010.0405, ISSN：0361-5995, Web of Science ID：WOS:000293076400012
• Relationship between specific surface area and the dry end of the water retention curve for soils with varying clay and organic carbon contents　　　　　　　　　　　　　　　
  Augustus C. Resurreccion; Per Moldrup; Markus Tuller; T. P. A. Ferre; Ken Kawamoto; Toshiko Komatsu; Lis Wollesen De Jonge
  WATER RESOURCES RESEARCH, 巻：47, 2011年06月, ［査読有り］
  Accurate description of the soil water retention curve (SWRC) at low water contents is important for simulating water dynamics and biochemical vadose zone processes in arid environments. Soil water retention data corresponding to matric potentials of less than -10 MPa, where adsorptive forces dominate over capillary forces, have also been used to estimate soil specific surface area (SA). In the present study, the dry end of the SWRC was measured with a chilled-mirror dew point psychrometer for 41 Danish soils covering a wide range of clay (CL) and organic carbon (OC) contents. The 41 soils were classified into four groups on the basis of the Dexter number (n = CL/OC), and the Tuller-Or (TO) general scaling model describing water film thickness at a given matric potential (<-10 MPa) was evaluated. The SA estimated from the dry end of the SWRC (SA_SWRC) was in good agreement with the SA measured with ethylene glycol monoethyl ether (SA_EGME) only for organic soils with n >10. A strong correlation between the ratio of the two surface area estimates and the Dexter number was observed and applied as an additional scaling function in the TO model to rescale the soil water retention curve at low water contents. However, the TO model still overestimated water film thickness at potentials approaching ovendry condition (about -800 MPa). The semi-log linear Campbell-Shiozawa-Rossi-Nimmo (CSRN) model showed better fits for all investigated soils from -10 to -800 MPa and yielded high correlations with CL and SA. It is therefore recommended to apply the empirical CSRN model for predicting the dry part of the water retention curve (-10 to -800 MPa) from measured soil texture or surface area. Further research should aim to modify the more physically based TO model to obtain better descriptions of the SWRC in the very dry range (-300 to -800 MPa).
  AMER GEOPHYSICAL UNION, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1029/2010WR010229
  DOI ID：10.1029/2010WR010229, ISSN：0043-1397, Web of Science ID：WOS:000292152900001
• Two-Region Extended Archie's Law Model for Soil Air Permeability and Gas Diffusivity　　　　　　　　　　　　　　　
  Shoichiro Hamamoto; Per Moldrup; Ken Kawamoto; Lis Wollesen de Jonge; Per Schjonning; Toshiko Komatsu
  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, 巻：75, 号：3, 開始ページ：795, 終了ページ：806, 2011年05月, ［査読有り］
  The air permeability (k(a)) and soil gas diffusion coefficients (D(p)) are controlling factors for gas transport and fate in variably saturated soils. We developed a unified model for k(a) and D(p) based on the classical Archie's law, extended by: (i) allowing for two-region gas transport behavior for structured soils, with the natural field moisture condition (set at -100 cm H(2)O matric potential [pF 2]) as the reference (spliced) point between the large-pore (drained pore diameter >= 30 mu m at pF <= 2) and the small-pore (subsequently drained pores <30 mu m at pF > 2) regions, and (ii) including a percolation threshold, set as 10% of the total porosity for structureless porous media or 10% of the porosity in the large-pore region for structured soils. The resulting extended Archie's law with reference point (EXAR) models for k(a) and D(p) were fitted to the measured data. For both structureless and structured porous media, Archie's saturation exponent (n) was higher for D(p) than for k(a), indicating higher water blockage effects on gas diffusion. For structured soils, the saturation exponent for the large-pore region (n(1)) was lower than for the small-pore region (n(2)). Generally, n(1) values of similar to 1 for k(a) and 2 for D(p) and n(2) values of 4/3 for k(a) and 7/3 for D(p) described the data well. Two reference-point expressions for k(a) at pF 2 were also developed and tested together with existing models for D(p) at pF 2 against independent data across soil types. The best-performing reference-point models were a k(a) model based on the classical Kozeny equation and the Moldrup D(p) model.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/sssaj2010.0207
  DOI ID：10.2136/sssaj2010.0207, ISSN：0361-5995, Web of Science ID：WOS:000290856500004
• Density-Corrected Models for Gas Diffusivity and Air Permeability in Unsaturated Soil　　　　　　　　　　　　　　　
  T. K. K. Chamindu Deepagoda; Per Moldrup; Per Schjonning; Lis Wollesen de Jonge; Ken Kawamoto; Toshiko Komatsu
  VADOSE ZONE JOURNAL, 巻：10, 号：1, 開始ページ：226, 終了ページ：238, 2011年02月, ［査読有り］
  Accurate prediction of gas diffusivity (D(p)/D(O)) and air permeability (k(a)) and their variations with air-filled porosity (epsilon) in soil is critical for simulating subsurface migration and emission of climate gases and organic vapors. Gas diffusivity and air permeability measurements from Danish soil profile data (total of 150 undisturbed soil samples) were used to investigate soil type and density effects on the gas transport parameters and for model development. The measurements were within a given range of matric potentials (-10 to -500 cm H(2)O) typically representing natural field conditions in subsurface soil. The data were regrouped into four categories based on compaction (total porosity phi <0.4 or >0.4 m(3) m(-3)) and soil texture (volume-based content of clay, silt, and organic matter <15 or >15%). The results suggested that soil compaction more than soil type was the major control on gas diffusivity and to some extent also on air permeability. We developed a density-corrected (D-C) D(p)(epsilon)/D(O) model as a generalized form of a previous model for D(p)/D(O) at -100 cm H2O of matric potential (D(p,100)/D(O)). The D-C model performed well across soil types and density levels compared with existing models. Also, a power-law k(a) model with exponent 1.5 (derived from analogy with a previous gas diffusivity model) used in combination with the D-C approach for k(a,100) (reference point) seemed promising for k(a)(epsilon) predictions, with good accuracy and minimum parameter requirements. Finally, the new D-C model concept for gas diffusivity was extended to bimodal (aggregated) media and performed well against data for uncompacted and compacted volcanic ash soil.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/vzj2009.0137
  DOI ID：10.2136/vzj2009.0137, ISSN：1539-1663, Web of Science ID：WOS:000287573300019
• MOBILIZATION AND LEACHING OF NATURAL AND WATER DISPERSIBLE COLLOIDS IN AGGREGATED VOLCANIC ASH SOIL COLUMNS　　　　　　　　　　　　　　　
  Chamindu T. K. K. Deepagoda; Ken Kawamoto; Hirotaka Saito; Lis Wollesen de Jonge; Per Moldrup; Toshiko Komatsu
  SOILS AND FOUNDATIONS, 巻：51, 号：1, 開始ページ：123, 終了ページ：132, 2011年02月, ［査読有り］
  Colloid-facilitated transport enhances migration of strongly sorbing compounds (e.g., radionuclides, phosphorus, heavy metals) in soil and groundwater. Mobilization, transport and deposition of soil colloids are the underlying processes governing colloid-facilitated contaminant transport. Although significant progress has been made in simulating mobilization and transport/deposition of model colloids in different collector systems, it may be inadequate for the prediction of natural colloidal behavior in the subsurface. This study quantifies the leaching of natural volcanic ash soil colloids (NC) as well as the simultaneous transport of applied water dispersible soil colloids (WDC) in aggregated volcanic ash soil columns. Two water-saturated soil columns were irrigated with artificial irrigation water (AIW) at an intensity of 80 mm/hr for 60 hours. Two additional columns were irrigated at the same intensity, but a colloidal suspension of 5 mg/L was applied after 20 hours for a period of 20 hours. Effluent colloid concentrations were measured in each experiment. HYDRUS-1D was used for the simulation and estimation of colloid transport parameters. The results clearly showed different kinetics for applied colloid transport and natural colloid leaching. Transport of applied WDC followed first-order attachment kinetics, while the two-site equilibrium/kinetic model with equal fractions of equilibrium and kinetic sites best described the leaching of NC. Coupling these best model approaches well predicted the simultaneous leaching of natural and applied colloids, hereby providing a useful tool for the design of colloid-based in-situ soil remediation systems.
  JAPANESE GEOTECHNICAL SOC, 英語, 研究論文（学術雑誌）
  ISSN：0038-0806, Web of Science ID：WOS:000292233600010
• A Simple Beta-Function Model for Soil-Water Repellency as a Function of Water and Organic Carbon Contents　　　　　　　　　　　　　　　
  Anurudda Kumara Karunarathna; Ken Kawamoto; Per Moldrup; Lis Wollesen de Jonge; Toshiko Komatsu
  SOIL SCIENCE, 巻：175, 号：10, 開始ページ：461, 終了ページ：468, 2010年10月, ［査読有り］
  Soil-water content (theta) and soil organic carbon (SOC) are key factors controlling the occurrence and magnitude of soil-water repellency (WR). Although expressions have recently been proposed to describe the nonlinear variation of WR with theta, the inclusion of easily measurable parameters in predictive WR(theta) models is still lacking. In this study, a simple empirical beta function was suggested to describe the effect of changing soil-water content on the change of WR given as apparent contact angle (alpha) measured by the molarity of ethanol droplet (MED) method. The beta function for predicting alpha(theta) is based on measurement of WR on air-dry soil and three additional model parameters: the water contents at which the maximum WR (highest alpha) occurs and where WR ceases (alpha = 90 degrees), and the maximum alpha value. The MED data for three data sets from literature comprising WR measurements across moisture conditions for 19 soils were used to test the model. The beta function successfully reproduced all the measured soil-water repellency characteristic, alpha(theta), curves. Significant correlations were found between model parameters and SOC content (1%-14%). The model was independently tested against data for further three soils and performed accurately for all three. Consequently, we suggest that the alpha(theta) model represents a useful strategy to predict the entire soil-water repellency characteristic curve, and thus potential risks for enhanced runoff and preferential (fingered) soil-water flow at given initial soil-water contents, from measurements of only air-dry soil-water repellency and SOC content.
  LIPPINCOTT WILLIAMS & WILKINS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1097/SS.0b013e3181f55ab6
  DOI ID：10.1097/SS.0b013e3181f55ab6, ISSN：0038-075X, Web of Science ID：WOS:000282562500001
• Two-Region Model for Soil Water Repellency as a Function of Matric Potential and Water Content　　　　　　　　　　　　　　　
  Anurudda Kumara Karunarathna; Per Moldrup; Ken Kawamoto; Lis Wollesen de Jonge; Toshiko Komatsu
  VADOSE ZONE JOURNAL, 巻：9, 号：3, 開始ページ：719, 終了ページ：730, 2010年08月, ［査読有り］
  Soil water repellency (WR) occurs worldwide and affects hydrologic processes such as infiltration, preferential flow, and surface erosion. The degree of WR varies with soil organic C (SOC) and water contents. In this study, we measured WR (by ethanol molarity) as a function of moisture conditions for two soil profiles (17 layers, of which 13 exhibited WR), representing different vegetation and SOC between 0.6 and 14%. Generally, WR was found at SOC >= 2%. Based on measured data, a two-region water repellency (TRWR) model was developed. The model assumes two linear regions in a WR vs. pF (= log[-psi], where psi is the soil water matric potential in centimeters of H(2)O) plot, with linear increase in WR from the moisture content where WR first occurs during drying to the maximum WR at pF(WR-max), and a linear decrease from pFWR-max until ambient air-dried conditions. The van Genuchten soil water retention model was used to convert WR-theta (where theta is the volumetric water content) to WR-pF. The TRWR model fitting parameters, slopes, and intercepts, were all highly correlated with SOC (R(2) > 0.8). The TRWR model was tested against an independent data set for five soils with 2 to 12% SOC and predicted well the measured WR-theta and WR-pF relations. For high-SOC surface soils, the TRWR model seems promising to predict WR from fully wettable to ambient air-dried conditions, i.e., within the interval where WR-induced fingered water flow probably occurs. Finally, our data imply that clay saturation by SOC (quantified by the so-called Dexter index) is useful for predicting if soils are likely to exhibit WR.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/vzj2009.0124
  DOI ID：10.2136/vzj2009.0124, ISSN：1539-1663, Web of Science ID：WOS:000284058700020
• Excluded-volume expansion of Archie's law for gas and solute diffusivities and electrical and thermal conductivities in variably saturated porous media　　　　　　　　　　　　　　　
  Shoichiro Hamamoto; Per Moldrup; Ken Kawamoto; Toshiko Komatsu
  WATER RESOURCES RESEARCH, 巻：46, 2010年06月, ［査読有り］
  Describing and predicting gas and solute diffusivities and electrical and thermal conductivities under variably saturated fluid conditions are necessary for simulating gas, solute, and heat transport in soils. On the basis of comprehensive data for gas (D(p)) and solute (D(s)) diffusivities and electrical (EC) and thermal (TC) conductivities for differently textured and variably saturated soils, we investigated analogies and differences between the four parameters. At fluid (water or air) saturation, relative parameter values for D(p), D(s), and EC were all well described by an excluded- volume expansion of Archie's first law. The cementation exponent in Archie's first law was close to 1.5 for all parameters. At fluid- unsaturated conditions, relative values of D(p), D(s), and EC (normalized at fluid saturation) were well described by an excluded- volume expansion of Archie's second law. In the case of relative TC, the saturation exponent in Archie's second law was substituted by the inverse of it for the three other parameters since water bridge effects dramatically enhance the TC with increasing moisture contents in relatively dry porous media. If appropriate but different expressions for a percolation threshold in Archie's second law were applied for the four parameters, a saturation exponent value of around 2.0 generally gave accurate predictions of all four parameters for differently textured soils. Finally, the excludedvolume expansion of Archie's second law was modified to also represent porous media with bimodal pore size distribution and well- described data for D(p) and D(s) in aggregated soil.
  AMER GEOPHYSICAL UNION, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1029/2009WR008424
  DOI ID：10.1029/2009WR008424, ISSN：0043-1397, Web of Science ID：WOS:000278993700002
• Hierarchical, Bimodal Model for Gas Diffusivity in Aggregated, Unsaturated Soils　　　　　　　　　　　　　　　
  Augustus C. Resurreccion; Per Moldrup; Ken Kawamoto; Shoichiro Hamamoto; Dennis E. Rolston; Toshiko Komatsu
  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, 巻：74, 号：2, 開始ページ：481, 終了ページ：491, 2010年03月, ［査読有り］
  The soil gas diffusion coefficient (D(p)) and its dependency on soil air content, epsilon, and tortuosity-connectivity of the air-filled pore networks control the transport and fate of gaseous-phase contaminants in variably saturated soil. The bimodality in pore size distribution of structured soil often yields a variation of D(p) with epsilon in the intraaggregate pore region that is distinctly different from that in the interaggregate region. Data imply a highly nonlinear behavior of soil gas diffusivity, D(p)(epsilon)/D(o) (where D(o) is the gas diffusion coefficient in free air), in the interaggregate region of aggregated soils similar to that of structureless soils with a unimodal pore size distribution, probably due to diffusion-limiting effects by connected water films at low epsilon. In contrast, for the intraaggregate region, we show that the impedance factor F* (= D(p)/epsilon D(o)) and tortuosity factor T [= (1/F*)(1/2)] are approximately constant for most soil media. We suggest a typically well-defined separation between the two pore regions at the minimum for the pore connectivity factor X* [= log(D(p)/D(o))/log(epsilon)], at which point the interaggregate pores are devoid of water while the intraaggregate pore region is water saturated. Based on this, a hierarchical two independent region (TIR) D(p)/D(o) model was developed by applying a cumulative series of Buckingham-Currie power-law functions, F epsilon(X). A nonlinear, water-content-dependent. expression for F best described the measured D(p)/D(o) in the interaggregate region, while constant F (around 0-5) and X(around 1) generally sufficed for the intraaggregate region. The TIR model better predicted gas diffusivities for both aggregate fractions and highly structured soils across the entire range of moisture conditions with MISE reduced by two to five times compared with traditional predictive D(p)(epsilon)/D(o) models.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/sssaj2009.0055
  DOI ID：10.2136/sssaj2009.0055, ISSN：0361-5995, Web of Science ID：WOS:000275187300016
• 泥炭林土壌の温室効果ガスの生成と消失
  森本聡; 永田修; 川本健; 長谷川周一
  土壌の物理性, 号：113, 開始ページ：3, 終了ページ：12, 2009年11月, ［査読有り］
  日本語, 研究論文（学術雑誌）
  ISSN：0387-6012, J-Global ID：201002215564608105
• Unified Measurement System for the Gas Dispersion Coefficient, Air Permeability, and Gas Diffusion Coefficient in Variably Saturated Soil　　　　　　　　　　　　　　　
  Shoichiro Hamamoto; Per Moldrup; Ken Kawamoto; Toshiko Komatsu; Dennis E. Rolston
  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, 巻：73, 号：6, 開始ページ：1921, 終了ページ：1930, 2009年11月, ［査読有り］
  The transport of gaseous compounds in soil takes place by gas diffusion, advection, and dispersion. Gas transport processes are influenced by tic soil-gas diffusion coefficient (D), air permeability (k(a)) and soil-gas dispersion coefficient (D(H)), respectively. Of three gas transport parameters, DH is the least understood especially hov it is correlated to soil type, moisture conditions, and other transport parameters (i.e., D(P) and k(a)). In this study, a unified measurement system (UMS) that enables sequential measurement of D(P), k(a), and D(H) on the same soil core was developed. The experimental sequence is based on a two-chamber measurement of DH and k(a), followed by a one-chamber measurement of L P. Gaseous oxygen concentration and air pressure sensors are located in inlet and outlet chambers as well as at multiple points along the soil column. Using different particle-size fractions of non-aggregated (Toyoura sand) and aggregated (Nishi-Tokyo loam) soils, the effects of soil structure, particle (aggregate) size, and column scale (5-cm i.d. and 30-cm or 60-cm length) on the three gas transport parameters were investigated. For both soils, D(H) linearly increased with increasing pore-air velocity. For Toyoura sand, gas dispersivity (lambda = D(H)/u(0)) decreased with increasing soil-air content, while for Nishi-Tokyo loam, gas dispersivity decreased with increasing soil-air content to a minimum value when inter-aggregate pores were drained and increased again whether pores inside the soil aggregates started to act as tortuous air-filled pathways. In the arterial bore region (corresponding to the total pore volume for Narita sand and the inter-aggregate pore volume for Nishi-Tokyo loam), a linear relation between tortuosity of the air-filled pore network (T, calculated from D(P)) and the gas dispersivity (lambda) was observed.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/sssaj2009.0012
  DOI ID：10.2136/sssaj2009.0012, ISSN：0361-5995, Web of Science ID：WOS:000271752700020
• The Solute Diffusion Coefficient in Variably Compacted, Unsaturated Volcanic Ash Soils　　　　　　　　　　　　　　　
  Shoichiro Hamamoto; Mandadige Samintha Anne Perera; Augustus Resurreccion; Ken Kawamoto; Shuichi Hasegawa; Toshiko Komatsu; Per Moldrup
  VADOSE ZONE JOURNAL, 巻：8, 号：4, 開始ページ：942, 終了ページ：952, 2009年11月, ［査読有り］
  The solute diffusion coefficient in soil (D(s)) and its dependency on the soil water content (theta), soil type, and compaction govern the transport and fate of dissolved chemicals in the soil vadose zone. Only a few studies have quantified solute diffusivity (D(s)/D(0), where D(s) and D(0) are the solute diffusion coefficients in soil and pure water, respectively) for variably compacted soils with different textures. We measured the D(s) for KCI on five different soils from Japan: two volcanic ash soils (Andisols) at different bulk densities, two sandy soils, and a loamy soil. The D(s) was measured across a wide range of theta using the half-cell method. The D(s)/D(0) values for Andisols with bimodal pore size distribution were comparatively lower than for the other soils. Opposite to the behavior for sandy soils, the D(s)/D(0) for Andisols at a given theta decreased markedly with increasing bulk density under wet conditions but Increased with increasing bulk density under dry conditions. Data for all soil types including sandy soils with unimodal pore size distribution implied a two-region behavior when plotted as log(D(s)/D(0)) vs. theta. We suggest that the similar behavior across soil types can be explained by regions of low and high water phase connectivity for relatively structureless soils and by high Intraaggregate and low interaggregate water phase tortuosity for aggregated soils. Among a number of tested predictive models for D(s)/D(0), the Penman-Millington-Quirk model, which requires knowledge of only theta and total porosity, performed best across soil types.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/vzj2008.0184
  DOI ID：10.2136/vzj2008.0184, ISSN：1539-1663, Web of Science ID：WOS:000271936900012
• Effect of Particle Size and Soil Compaction on Gas Transport Parameters in Variably Saturated, Sandy Soils　　　　　　　　　　　　　　　
  Shoichiro Hamamoto; Per Moldrup; Ken Kawamoto; Toshiko Komatsu
  VADOSE ZONE JOURNAL, 巻：8, 号：4, 開始ページ：986, 終了ページ：995, 2009年11月, ［査読有り］
  The soil gas diffusion coefficient (D(p)) and air permeability (k(a)) and their dependency on soil air content (epsilon) control gas diffusion and advection in soils. This study investigated the effects of average particle size (D(50)) and dry bulk density (rho(b)) on D(p) and k(a) for six sandy soils under variably saturated conditions. Data showed that particle size markedly affects the effective diameter of the drained pores active in leading gas through the sample at -100 cm H(2)O of soil water matric potential (calculated from D(p) and k(a)) as well as the average pore diameter at half saturation (calculated from the water retention curve), both exhibiting similar and exponential relationships with D(50) Under variably saturated conditions, higher D(p) and k(a) in coarser sand (larger D(50)) were observed due to rapid gas diffusion and advection through the less tortuous large-pore networks. In addition, soil compaction (larger rho(b)) simultaneously caused reduced water blockage effects and a reduction of large-pore space, resulting in higher D(p)(epsilon) but lower k(a)(epsilon). Two recent models for D(p)(epsilon) and k(a)(epsilon) were evaluated: the water-induced linear reduction (WLR) model for D(p), and the reference-point power law (RPL) model for k(a), with reference point ka set at -100 cm H(2)O. The performance of both models for the sandy soils (particle size range 0.02-0.9 mm) was improved if the pore connectivity-tortuosity factor and water blockage factors were assumed to be functions of D(50) and rho(b). Water blockage factors, N for the WLR D(p)(epsilon) model and M for the RPL k(a)(epsilon) model, showed a strong nonlinear relationship (R(2) = 0.95) that seems promising for predicting D(p)(epsilon) from the more easily measureable k(a)(epsilon).
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/vzj2008.0157
  DOI ID：10.2136/vzj2008.0157, ISSN：1539-1663, Web of Science ID：WOS:000271936900016
• 境界条件が原位置通気係数の算出に用いられる形状係数に及ぼす影響　　　　　　　　　　　　　　　
  濱本昌一郎; 川本健; 長森正尚; 小松登志子; Per Moldrup
  土木学会論文集C, 巻：65, 号：2, 開始ページ：579, 終了ページ：586, 2009年, ［査読有り］
  原位置通気係数（K_{a, insitu}）は，比較的低コストかつ迅速測定が可能であり，地盤内でのガスや水の移動特性を把握する上で非常に有効な物質移動パラメータである．一般に，K_{a, insitu}の計算には，地盤内の三次元空気流れを考慮するための形状係数が組み込まれる．本研究では，有限要素法による数値解析により地盤内空気流れをシミュレーションし，得られた形状係数やK_{a, insitu}を既往の研究結果と比較するとともに，形状係数に横境界や下端境界条件の変化が及ぼす影響を数値解析および模型実験により検証した．その結果，K_{a, insitu}測定時の下端境界条件が形状係数やK_{a, insitu}に大きな影響を与えることが明らかにされた．特に，地盤表層付近に不透気層が存在する場合は，調査地点での境界条件を考慮した形状係数を求め，Ka, insitu を適切に算出することが必要である．
  公益社団法人 土木学会, 日本語
  DOI：https://doi.org/10.2208/jscejc.65.579
  DOI ID：10.2208/jscejc.65.579, eISSN：1880-604X, CiNii Articles ID：130004943055
• Adsorption of 2,4-dichlorophenoxyacetic acid onto volcanic ash soils: Effects of pH and soil organic matter　　　　　　　　　　　　　　　
  Ei Mon, E; T. Hirata; K. Kawamoto; S. Hiradate; T. Komatsu; P. Moldrup
  EnvironmentAsia, 巻：2, 号：1, 開始ページ：1, 終了ページ：9, 2009年, ［査読有り］
  英語, 研究論文（学術雑誌）
• USEFUL SOIL-WATER REPELLENCY INDICES: LINEAR CORRELATIONS　　　　　　　　　　　　　　　
  Carlos M. Regalado; Axel Ritter; Lis W. de Jonge; Ken Kawamoto; Toshiko Komatsu; Per Moldrup
  SOIL SCIENCE, 巻：173, 号：11, 開始ページ：747, 終了ページ：757, 2008年11月, ［査読有り］
  Water repellency (WR) has been classically characterized at fixed (usually oven-dry) soil water content (theta(g)) in terms of the soil water contact angle (CA), alpha. However, a has been previously reported to depend upon theta(g) in a nonlinear fashion, such that WR increases from a wettable state close to saturation (theta(g-min)) up to a maximum, alpha(max), decreasing afterward either monotonically or rising again to a second local or absolute a maximum nearby the dried soil state. Hence, a CA versus water content (alpha-theta(g)) curve may be described in terms of different WR parameters, such as theta(g-min), theta(g-max), alpha(max), or the integrated area below the alpha-theta(g) curve S Based on previous alpha-theta(g) measurements carried out with the molarity of an ethanol droplet (MED) test, both in mineral and volcanic soils from different world regions, including cultivated and natural forest soils, and textures ranging from clay-loam to sandy, we confirm here the usefulness of the integrated area below the alpha-theta(g) curve (S) as a WR describing index for a large variety of alpha-theta(g) curve shapes. We found a simple relationship between S and the soil water content at which WR is triggered, theta(g-min), such that S = 16.903 theta(g-min) (R-2 = 0.946), which provides an easy method for the rapid characterization of the overall WR degree of soils. S was also linearly correlated with the soil organic matter (SOM) content (R-2 = 0.817) for 1 g (100 g)(-1) < SOM < 88 g (100 g)(-1), such that the best estimate of S was that obtained by combining linearly both theta(g-min) and the SOM content (R-2 = 0.990). Linear correlations were also found between theta(g-max), that is, the soil water content at which alpha is maximum, and S (R-2 = 0.834) or the SOM content (R-2 = 0.705), and consequently between theta(g-max) and theta(g-min) (R-2 = 0.830). In addition, both theta(g-min) and theta(g-max) were found to depend linearly upon the soil water content at - 33 kPa and - 1500 kPa, respectively. Finally, a mean soil WR may be defined as the ratio S/theta(g-min). We found that the maximum 2 CA, alpha(max), and the mean soil WR S/theta(g-min) were positively correlated (R-2 = 0.780), such that a particular soil with high (low) values of maximum CA is expected to exhibit a high (low) WR degree on average across the whole water regimen from - 33 kPa down to oven-dry moisture. Such an estimate of the mean WR index S/theta(g-min) was further improved if both and the alpha(max) and the SOM content were available (R-2 = 0.825). (Soil Science 2008;173:747-757)
  LIPPINCOTT WILLIAMS & WILKINS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1097/SS.0b013e31818d4163
  DOI ID：10.1097/SS.0b013e31818d4163, ISSN：0038-075X, CiNii Articles ID：80019976641, Web of Science ID：WOS:000260935900001
• Linear model to predict soil-gas diffusivity from two soil-water retention points in unsaturated volcanic ash soils　　　　　　　　　　　　　　　
  Augustus C. Resurreccion; Toshiko Komatsu; Ken Kawamoto; Masanobu Oda; Seiko Yoshikawa; Per Moldrup
  SOILS AND FOUNDATIONS, 巻：48, 号：3, 開始ページ：397, 終了ページ：406, 2008年06月, ［査読有り］
  Risk assessment and design of remediation methods at soil sites polluted with gaseous phase contaminant require an accurate description of soil-gas diffusion coefficient (D(p)) which is typically governed by the variations in soil air-filled porosity (nu(a)). For undisturbed volcanic ash soils, recent studies have shown that a linear D(p)(nu(a)) model, taking into account inactive air-filled pore space (threshold soil-air content, nu(a), (th)), captured the D(p) data across the total soil moisture range from wet to completely dry conditions. In this study, we developed a simple, easy to apply, and still accurate linear D(p)(nu(a)) model for undisturbed volcanic ash soils. The model slope C and intercept (interpreted as nu(a), (th) were derived using the classical Buckingham (1904) D(p)(nu(a)) power-law model, nu(x)(a), at two soil-water matric potentials of pF 2 (near field capacity condition) and pF 4.1 (near wilting point condition), and assuming the same value for the Buckingham exponent (X = 2.3) in agreement with measured data. This linear D(p)(nu(a)) prediction model performed better than the traditionally-used non-linear D(p)(nu(a)) models, especially at dry soil conditions, when tested against several independent data sets from literature. Model parameter sensitivity analysis on soil compaction effects showed that a decrease in slope C and nu(a), (th) due to uniaxial reduction of air-filled pore space in between aggregates markedly affects the magnitude of soil-gas diffusivity. We recommend the new D(p)(nu(a)) model using only the soil-air contents at two soil-water matric potential conditions (field capacity and wilting point) for a rapid assessment of the entire D(p)-nu(a) function.
  JAPANESE GEOTECHNICAL SOC, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.3208/sandf.48.397
  DOI ID：10.3208/sandf.48.397, ISSN：0038-0806, CiNii Articles ID：110007327346, Web of Science ID：WOS:000258745000007, 共同研究・競争的資金等ID：44511240
• Variable pore connectivity factor model for gas diffusivity in unsaturated, aggregated soil　　　　　　　　　　　　　　　
  Augustus C. Resurreccion; Per Moldrup; Ken Kawamoto; Seiko Yoshikawa; Dennis E. Rolston; Toshiko Komatsu
  VADOSE ZONE JOURNAL, 巻：7, 号：2, 開始ページ：397, 終了ページ：405, 2008年05月, ［査読有り］
  The soil gas diffusion coefficient (D(p)) and its variations with soil air content (epsilon) and soil water matric potential (psi) control vadose zone transport and emissions of volatile organic chemicals and greenhouse gases. This study revisits the 1904 Buckingham power-law model where D(p) is proportional to E with X characterizing the tortuosity and connectivity of air-filled pore space. One hundred years later, most models linking D(p) (epsilon) to Soil water retention and pore size distribution still assume that the pore connectivity factor, X, is a constant for a given soil. We show that X varies strongly with both epsilon and matric potential [given as pF = log(psi, cm H(2)O)] for individual soils ranging from undisturbed sand to aggregated volcanic ash soils (Andisols). For Andisols with bimodal pore size distribution, the X-pF function appears symmetrical. The minimum X value is typically around 2 and was observed close to psi of -1000 cm H(2)O (pF 3) when inter-aggregate voids are drained. To link D(p) with bimodal pore size distribution, we coupled a two-region van Genuchten soil water retention model with the Buckingham D(p) (epsilon) model, assuming X to vary symmetrically around a given pF. The coupled model well described D(p) as a function of both epsilon and psi for both repacked and undisturbed Andisols and for other soil types. By merely using average values of the three constants in the proposed symmetrical X-pF expression, predictions of D(p) were better than with traditional models.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/vzj2007.0058
  DOI ID：10.2136/vzj2007.0058, ISSN：1539-1663, Web of Science ID：WOS:000256204600001, 共同研究・競争的資金等ID：44511240
• 泥炭土のガス拡散・透気特性に脱水収縮が及ぼす影響　　　　　　　　　　　　　　　
  飯塚健仁; 川本健; 小松登志子; 長谷川周一
  土木学会論文集, 巻：G 64, 号：3, 開始ページ：242, 終了ページ：249, 2008年, ［査読有り］, ［責任著者］
  日本語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2208/jscejg.64.242
  DOI ID：10.2208/jscejg.64.242
• Water repellency of aggregate size fractions of a volcanic ash soil　　　　　　　　　　　　　　　
  Ken Kawamoto; Per Moldrup; Toshiko Komatsu; Lis Wollesende de Jonge; Masanobu Oda
  SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, 巻：71, 号：6, 開始ページ：1658, 終了ページ：1666, 2007年11月, ［査読有り］, ［筆頭著者, 責任著者］
  Water repellency (WR) of soils can induce hydrological problems such as reduced water infiltration, enhanced surface runoff and erosion, and the forming of preferential flow patterns in soil. Although soil organic matter (SOM) may cause both soil aggregation and a hydrophobic-material-coating of aggregates, little is known about WR in aggregated soils. We investigated the degree of WR as functions of volumetric water content (theta) and pF [= log (-Psi; soil-water potential)] for sieved fractions of a volcanic ash soil samples from different depths with varying soil organic carbon (SOC) contents of between 1.1 and 12.3%. Water repellency was determined by the molarity of ethanol droplet (MED) test. Water repellency was observed in the samples with SOC >= 4.6%, and the effects of sample pretreatments (pressure chamber desorption, air-drying at 20 degrees C, and oven-drying at 60 degrees C on the degree of WR were small. The degree of WR varied greatly with both SOC content, theta, and pF. Peaks of WR were observed when the water retained in intra-aggregate pores was drained to a moderate extent with the corresponding pF values located in a relatively narrow range from 3.2 to 3.6. This indicates that the hydrophobicity of high-SOC aggregate surfaces might be enhanced the most at a specific soil-water potential. Examining relations between water repellency parameters, the integrated areas below the WR-theta and WR-pF curves were useful indexes for characterizing WR, and linear relationships between the integrated areas and both SOC and water contents at maximum repellency were found.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/sssaj2006.0284
  DOI ID：10.2136/sssaj2006.0284, ISSN：0361-5995, CiNii Articles ID：80018041716, Web of Science ID：WOS:000251092100002, 共同研究・競争的資金等ID：44511243
• Gas diffusivity and air permeability in a volcanic ash soil profile: Effects of organic matter and water retention　　　　　　　　　　　　　　　
  Augustus C. Resurreccion; Ken Kawamoto; Toshiko Komatsu; Per Moldrup; Kuniaki Sato; Dennis E. Rolston
  SOIL SCIENCE, 巻：172, 号：6, 開始ページ：432, 終了ページ：443, 2007年06月, ［査読有り］
  The soil-gas diffusion coefficient (D-p) and air permeability (k(a)) govern the transport and emission of greenhouse gases and volatile organic chemicals in the unsaturated zone. The effects of soil organic matter and water retention on the two gas transport parameters are not well known. In this study, we measured D-p and k(a) in three depths of a volcanic ash soil (Amdisol) profile, with organic matter contents of 17% (0-5 cm depth), 4.7% (15-20 cm), and 0.2% (55-60 cm), respectively. Measurements were made on undisturbed samples at soil-water matric potentials from psi = - 10 cm H2O (pF 1) to - 12,600 cm H2O (pF 4.1) and, for Dp, also on air- and oven-dried samples. Soil-water retention was larger in the loworganic layer (55-60 cm) and similar for the other 2 organic layers. Soilgas diffusivity varied the most in the high-organic top layer (0-5 cm) and was lower for samples with total porosity exceeding 0.8 m(3) m(-3) likely because of additional inactive air-filled pore space created by interconnected water films. The threshold air-filled porosity (epsilon(th)) where Dp approached zero was on the average 0.05 m(3) m(-3) higher in the highorganic top layer (epsilon(th) around 0.2 m(3) m(-3)) compared with the lower layers. For air permeability, the low-organic layer (55-60 cm) behaved differently because of a different soil structure. A recent power law ka(C) model compared well with data between pF 1 and pF 3 but typically underestimated ka at pF 4.1 because of a sudden increase in pore connectivity. A recent linear D-p(epsilon) model for Andisols is further developed, with Eth and model slope C predicted from soil total porosity and volumetric content of intra-aggregate pores (soil-water content at pF 3). The linear model performed better than frequently used nonlinear D-p(epsilon) models, especially at low soil-water contents.
  LIPPINCOTT WILLIAMS & WILKINS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1097/SS.0b013e3180471c94
  DOI ID：10.1097/SS.0b013e3180471c94, ISSN：0038-075X, CiNii Articles ID：80018462143, Web of Science ID：WOS:000247353000002, 共同研究・競争的資金等ID：44511240
• Gas transport parameters along field transects of a volcanic ash soil　　　　　　　　　　　　　　　
  Augustus C. Resurreccion; Ken Kawamoto; Toshiko Komatsu; Per Moldrup; Noriatsu Ozaki; Dennis E. Rolston
  SOIL SCIENCE, 巻：172, 号：1, 開始ページ：3, 終了ページ：16, 2007年01月, ［査読有り］
  Variations in gas transport parameters at the field scale govern the transport, fate, and emission of greenhouse gases and volatile organic chemicals in soil. In this study, we evaluated predictive models for soil-gas diffusivity (D-p/D-o) and air permeability (k(a)) based on measurements along a 117-m transect and a parallel 33-m transect of a humic volcanic ash soil 3 (Andisol) in Nishi-Tokyo, Japan. Measurements were done on 100-cm(3) undisturbed soil samples, with 3-m spacing between sampling points, and included water retention, soil-gas diffusion coefficient (D) k(a) at different soil-water matric potentials, and saturated hydraulic conductivity. Traditionally used predictive gas diffusivity models underestimated D-p/D-o in wet soil and largely overestimated D-p/D-o under dry conditions because of soil aggregation effects. A linear model for D-p/D-o. as a function of air-filled porosity (epsilon), taking into account inactive/ remote air-filled pore space, accurately described D-p(epsilon)/D-o from wet to oven-dry conditions and well captured the spatial variations in D-p/D-o along the transects. The k(a) exhibited a nonlinear relation with epsilon. and k(a)(epsilon) was best predicted from a recently presented power-law model, with measured k(a) at -100 cm H2O of soil-water matric potential (k(a),100) as a reference point. Trends of decreasing soil-water retention and increasing epsilon along transects were observed. Similar trends in k(a) and saturated hydraulic conductivity were not observed because the convective fluid transport parameters were mainly governed by soil structure and not by fluid phase contents. Autocorrelograms suggested a spatial correlation range of 10 to 20 m for gas transport parameters (D-p/D-o and ka). Measurements of epsilon and k(a) at conditions close to -100 cm H2O of soil-water matric potential are suggested for rapid assessment of the magnitude and spatial variations in gas transport properties at the field scale.
  LIPPINCOTT WILLIAMS & WILKINS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1097/01.ss.0000235850.55944.04
  DOI ID：10.1097/01.ss.0000235850.55944.04, ISSN：0038-075X, CiNii Articles ID：80018673303, Web of Science ID：WOS:000243569100001, 共同研究・競争的資金等ID：44511240
• Gas transport parameters in the vadose zone: Development and tests of power-law models for air permeability　　　　　　　　　　　　　　　
  Ken Kawamoto; Per Moldrup; Per Schjonning; Bo V. Iversen; Toshiko Komatsu; Dennis E. Rolston
  VADOSE ZONE JOURNAL, 巻：5, 号：4, 開始ページ：1205, 終了ページ：1215, 2006年11月, ［査読有り］
  he soil-air permeability (k(a)) and its dependency on air-filled porosity (epsilon) govern convective air and gas transport in soil. For example, accurate prediction of k(a)(epsilon) is a prerequisite for optimizing soil vapor extraction systems for cleanup of soils polluted with volatile organic chemicals. In this study, we measured k(a) at different soil-water matric potentials down to 5.6-m depth, totaling 25 differently textured soil layers. Comparing k(a) and soil-gas diffusivity (D-p/D-0) measurements on the same soil samples suggested an analogy between how the two soil-gas transport parameters depend on epsilon. The exponent in a power-law model for k(a)(epsilon) was typically smaller than for D-p(epsilon)/D-0, however, probably due to the influence of soil structure and large-pore network being more pronounced for k(a) than for D-p/D-0. In analogy to recent gas diffusivity models and in line with capillary tube models for unsaturated hydraulic conductivity, two power-law k(a)(epsilon) models were suggested. One k(a)(epsilon) model is based on the Campbell pore-size distribution parameter b and the other on the content of larger pores (epsilon(100), corresponding to the air-filled porosity at -100 cm H2O of soil-water matric potential). Both new models require measured k(a) at -100 cm H2O (k(a,100)) as a reference point to obtain reasonably accurate predictions. If k(a,100) is not known, two expressions for predicting k(a,100) from epsilon(100) were proposed but will cause at least one order of magnitude uncertainty in predicted k(a). The k(a)(epsilon) model based on only epsilon(100) performed well in the model tests and is recommended together with a similar model for gas diffusivity for predicting variations in soil-gas transport parameters in the vadose zone.
  SOIL SCI SOC AMER, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2136/vzj2006.0030
  DOI ID：10.2136/vzj2006.0030, ISSN：1539-1663, Web of Science ID：WOS:000243724900015, 共同研究・競争的資金等ID：44511240
• Linking the gardner and campbell models for water retention and hydraulic conductivity in near-saturated soil　　　　　　　　　　　　　　　
  Ken Kawamoto; Per Moldrup; Ty P. A. Ferre; Markus Tuller; Ole H. Jacobsen; Toshiko Komatsu
  SOIL SCIENCE, 巻：171, 号：8, 開始ページ：573, 終了ページ：584, 2006年08月, ［査読有り］, ［筆頭著者, 責任著者］
  Linking the classical Gardner and Campbell models for soil hydraulic properties yields a combined Gardner-Campbell (GC) relationship for predicting unsaturated hydraulic conductivity (K) from soil-water retention. The new GC water retention and hydraulic conductivity relationships are described by simple linearized expressions based on Campbell-b-scaled values of volumetric soil-water content (0). The GC hydraulic properties models include four parameters, the pore connectivity parameter x (typically between 1 and 2), the Campbell pore size distribution parameter b, the Gardner macroscopic capillary length X, and the air-entry soil-water matric potential (psi(e)). In the GC model for K(theta), these parameters are merged into a single dimensionless parameter, A. The GC models are applied to seven different undisturbed soils within a soil-water matric potential psi with a range of 0 to -60 cm H2O. Results show that the simple GC psi(theta) model adequately describes water retention data close to saturation, and that the GC K(theta) model performs well for predicting near-saturated hydraulic conductivity. The GC water retention and hydraulic conductivity parameters were incorporated into Wooding's equation for steady-state infiltration rate to examine the effects of variability in physical characteristics on infiltration. The steady-state infiltration rate was less sensitive to the GC water retention and hydraulic conductivity parameters than the saturated hydraulic conductivity. The GC models, which combine advantages of the Gardner model for linearization of the Richards' equation and the simple Campbell model for soil-water retention, seem useful for describing or predicting near-saturated soil hydraulic properties and for stochastic simulations of field-scale water infiltration.
  LIPPINCOTT WILLIAMS & WILKINS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1097/01.ss.0000228035.72647.3c
  DOI ID：10.1097/01.ss.0000228035.72647.3c, ISSN：0038-075X, CiNii Articles ID：80019003470, Web of Science ID：WOS:000239875200001
• 土壌ガス拡散係数予測モデルの提案と国内土壌への適用　　　　　　　　　　　　　　　
  川本健; 小松登志子; PerMoldrup; 吉川省子; 藤川智紀
  土壌の物理性, 号：101, 開始ページ：37, 終了ページ：50, 2005年, ［査読有り］
  土壌物理学会, 日本語, 研究論文（学術雑誌）
  ISSN：0387-6012, CiNii Articles ID：40007202059, CiNii Books ID：AN00347581
• TDRコイルプローブ法による撥水性火山灰土壌の保水性評価　　　　　　　　　　　　　　　
  川本 健; Banyar Aung; Per Moldrup; 小松 登志子; 小田 匡寛
  農業土木学会論文集, 巻：72, 号：5, 開始ページ：531, 終了ページ：539, 2004年10月, ［査読有り］, ［筆頭著者, 責任著者］
  農業土木学会, 日本語, 研究論文（学術雑誌）
  ISSN：0387-2335, CiNii Articles ID：10013726291, CiNii Books ID：AN00201203, 共同研究・競争的資金等ID：44511243
• 火山灰土壌の撥水性評価に関する実験的研究 : 有機物含有量と初期水分量が及ぼす影響　　　　　　　　　　　　　　　
  川本 健; Banyar Aung
  農業土木学会論文集, 巻：72, 号：2, 開始ページ：193, 終了ページ：201, 2004年04月, ［査読有り］, ［筆頭著者, 責任著者］
  農業土木学会, 日本語, 研究論文（学術雑誌）
  ISSN：0387-2335, CiNii Articles ID：10012911085, CiNii Books ID：AN00201203, 共同研究・競争的資金等ID：44511243
• Moisture structures of laterally expanding fingering flows in sandy soils　　　　　　　　　　　　　　　
  K Kawamoto; S Mashino; M Oda; T Miyazaki
  GEODERMA, 巻：119, 号：3-4, 開始ページ：197, 終了ページ：217, 2004年04月, ［査読有り］, ［筆頭著者, 責任著者］
  Water sometimes infiltrates into a sandy soil along preferential flow paths called fingers, rather than homogeneously. In order to understand the physical fundamentals of fingering flow, we carried out two-dimensional infiltration tests under continuous rainfall. Each finger was composed of two moisture structure zones, a finger core and a finger-swelling zone surrounding the finger core. Each finger can be classified as a low-swell finger (LSF) or a high-swell finger (HSF) based on the swelling velocity. In LSF, water moves laterally across a constant potential boundary where sorptivity is a dominant factor in making the finger swell. In HSF, on the other hand, water moves laterally through a constant flux boundary where pressure gradient is a driving force. In the latter, accordingly, the corresponding water flux can be estimated by the hydraulic conductivity multiplied by the water pressure gradient. Based on these observations, we propose a growth model for a finger moving downward along with subsequent lateral expansion, which makes it possible to estimate the area of soil wetted by fingers. The estimated area is in a fairly good agreement with that observed. (C) 2003 Elsevier B.V. All rights reserved.
  ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.geoderma.2003.07.001
  DOI ID：10.1016/j.geoderma.2003.07.001, ISSN：0016-7061, CiNii Articles ID：80016533205, Web of Science ID：WOS:000220101400003, 共同研究・競争的資金等ID：44511243
• 現地計測と室内実験の組み合わせによる自然丘陵斜面表土の透水性評価　　　　　　　　　　　　　　　
  川本健; 大村大志; 小林邦宏; 久保順一
  土と基礎, 巻：52, 号：11, 開始ページ：35, 終了ページ：37, 2004年, ［筆頭著者, 責任著者］
  日本語, 研究論文（学術雑誌）
  共同研究・競争的資金等ID：44511243
• TDRコイルプローブ法による撥水性火山灰土壌の保水性評価　　　　　　　　　　　　　　　
  川本健; BanyarAung,PerMoldrup; 小松登志子; 小田匡寛
  農業土木学会論文集, 巻：233, 開始ページ：83, 終了ページ：91, 2004年, ［査読有り］, ［筆頭著者, 責任著者］
  日本語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.11408/jsidre1965.2004.531
  DOI ID：10.11408/jsidre1965.2004.531, 共同研究・競争的資金等ID：44511243
• 火山灰土壌の撥水性評価に関する実験的研究 -有機物含有量と初期水分量が及ぼす影響-　　　　　　　　　　　　　　　
  川本健; BanyarAung
  農業土木学会論文集, 巻：230, 開始ページ：75, 終了ページ：83, 2004年, ［査読有り］, ［筆頭著者, 責任著者］
  日本語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.11408/jsidre1965.2004.193
  DOI ID：10.11408/jsidre1965.2004.193, 共同研究・競争的資金等ID：44511243
• Microstructural interpretation on reliquefaction of saturated granular soils under cyclic loading　　　　　　　　　　　　　　　
  M Oda; K Kawamoto; K Suzuki; H Fujimori; M Sato
  JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING, 巻：127, 号：5, 開始ページ：416, 終了ページ：423, 2001年05月, ［査読有り］
  It is well known that the resistance to liquefaction of a saturated sand decreases sharply when it has been presheared, either cyclically or quasi statically, beyond a threshold value. The possible mechanism is discussed in light of recent findings on the microstructural anisotropy developed in preshearing (induced anisotropy). A columnlike structure, through which applied stress is mainly transmitted, grows parallel to the major principal stress direction in the strain hardening process. Voids, randomly distributed at first, are also connected in series between the columnlike structures. The anisotropic structure can carry the increasing stress as long as the major stress is applied parallel to the elongation direction of the structure. However, it becomes extremely unstable when the major stress is rotated. The excess pore-water pressure increases markedly under undrained cyclic loading, particularly when the connected voids are stressed perpendicular to their elongation direction. This is the reason why once liquefied sand sharply loses liquefaction resistance in a subsequent reliquefaction faction.
  ASCE-AMER SOC CIVIL ENGINEERS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1061/(ASCE)1090-0241(2001)127:5(416)
  DOI ID：10.1061/(ASCE)1090-0241(2001)127:5(416), ISSN：1090-0241, CiNii Articles ID：80012443432, Web of Science ID：WOS:000168293600004, 共同研究・競争的資金等ID：44511244
• 三軸試験装置における飽和砂の再液状化抵抗に及ぼす構造異方性の影響　　　　　　　　　　　　　　　
  鈴木輝一; 小田匡寛; 川本健; 藤森啓之
  構造工学論文集, 巻：46, 号：A, 開始ページ：289, 終了ページ：298, 2000年, ［査読有り］
  日本語, 研究論文（学術雑誌）
  共同研究・競争的資金等ID：44511244
• Hydro-Geological Study of Landslides Caused by Heavy Rainfall on August 1998 in Fukushima, Japan　　　　　　　　　　　　　　　
  KAWAMOTO K.
  Journal of Natural Disaster Science, 巻：22, 号：1, 開始ページ：13, 終了ページ：23, 2000年, ［査読有り］, ［筆頭著者, 責任著者］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.2328/jnds.22.13
  DOI ID：10.2328/jnds.22.13, ISSN：0388-4090, CiNii Articles ID：30018744648
• Fingering flow in homogeneous sandy soils under continuous rainfall infiltration　　　　　　　　　　　　　　　
  Kawamoto, K; T. Miyazaki
  Soils and Foundations, 巻：39, 号：4, 開始ページ：79, 終了ページ：91, 1999年, ［査読有り］, ［筆頭著者, 責任著者］
  rights: 社団法人地盤工学会rights: 本文データは学協会の許諾に基づきCiNiiから複製したものであるrelation: IsVersionOf: http://ci.nii.ac.jp/naid/110003945709/In order to establish a physical model leading to stable (uniform) and unstable (non-uniform fingering) flows in unsaturated soils, two-dimensional tests on continuous rainfall infiltration were carried out by changing not only the initial water content (air dry, 0.5%, 1.0%) but also the rainfall intensity (15,30,180 mm/h). The physical mechanism of fingering flow was discussed on the basis of precise suction measurements inside and outside the fingers. The results show that wetting fronts developed in unsaturated sandy soils can be classified into three types ; 1) fingering flow, 2) wavy front, and 3) plane front. Two types of fingering flow can be further distinguished by the difference of the swelling velocity ; i. e., low-swell finger and high-swell finger flows. In each of the low-swell and high-swell fingers, a core and a swelling zone are developed while a finger is growing. Based on suction measurements inside them, it is found that the water condition in the finger core changes from wetting to drying processes while the water condition in the swelling zone remains in the wetting process. This hysteretic behavior in the core can be explained by the moisture distribution changing along a finger from tip to tail. Fingers swell when water moves from a finger core to surrounding dry sand. Such a swelling process is mainly controlled by the hydraulic conductivity for the wetting process at a finger tail.
  社団法人地盤工学会, 英語, 研究論文（学術雑誌）
  DOI ID：10.3208/sandf.39.4_79, ISSN：1341-7452, CiNii Articles ID：110003945709, CiNii Books ID：AN10496056, 共同研究・競争的資金等ID：44511243
• 美唄泥炭地の持続的農業生産と土壌・水文・大気ダイナミックス －物質移動をフィールドサイエンスにみる－　　　　　　　　　　　　　　　
  宮崎毅; 中野政詩; 梅田安治; 粕渕辰昭; 伊藤純雄; 西村拓; 塩沢昌; 前村庸之; 川本健; 斎藤広隆; 神谷貴文; 飯山一平; 井本博美
  水利科学, 巻：41, 号：3, 開始ページ：27, 終了ページ：40, 1997年, ［査読有り］
  水利科学研究所, 日本語, 研究論文（学術雑誌）
  ISSN：0039-4858, CiNii Articles ID：120005773272, CiNii Books ID：AN00125003
• フィンガー流の形態による塩分溶脱効果の相違　　　　　　　　　　　　　　　
  川本健; 宮崎毅; 中野政詩
  農業土木学会論文集, 巻：64, 号：186, 開始ページ：89, 終了ページ：96, 1996年, ［査読有り］, ［筆頭著者, 責任著者］
  モデル実験を行い,豊浦標準砂と石英砂で発生するフィンガー流の形態を調べるとともに,フィンガー流が砂層のリーチングに与える影響を調べた.砂の平均粒径は豊浦標準砂が0.18mm,石英砂が0.64mmで,砂には風乾砂100g当たりNaCl1.65gを均一に混入した.実験は初期含水比が3種類(風乾,1%,2%),散水フラックスが2種類(30mm/h,180mm/h)の条件で行った.
  乾いた単一砂層の散水浸潤時に発生した浸潤の形状はフィンガー流,波状の浸潤前線,および滑らかな浸潤前緑に分類でき,さらにフィンガー流は非膨張型と膨張型の2種類に分類できた.
  非膨張型および膨張型フィンガー流内部の水移動は,サクション勾配が0に近い値を示したことから,主に重力勾配によって行われることが分かった.また非膨張型と膨張型は異なるサクション変化を示し,これはフィンガー内部の水分分布の違いによるものと考えられる.
  散水による塩類集積砂層のリーチングには浸潤の形状が大きく影響し,特に風乾条件では非膨張型フィンガー流の発生により,他の型に比べてリーチング効果が著しく低下した.
  The Japanese Society of Irrigation, Drainage and Rural Engineering, 日本語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.11408/jsidre1965.1996.981
  DOI ID：10.11408/jsidre1965.1996.981, ISSN：0387-2335, CiNii Articles ID：10016223879, CiNii Books ID：AN00201203

• 土壌水分ヒステリシスがガス・熱輸送係数に及ぼす影響　　　　　　　　　　　　　　　
  濱本 昌一郎; 川本 健; 小松 登志子
  CACS forum : 埼玉大学研究機構科学分析支援センター機関誌, 号：3, 開始ページ：6, 終了ページ：11, 2012年
  Knowledge of soil-gas and heat transport parameters is essential for simulating behaviors of greenhouse/toxic gases and changes in soil temperature in natural and man-made soil ecosystems, for example in urban polluted soil sites and the soil cover layer at municipal landfill sites. Degree of water-saturation at different water potentials (as described by the soil-water retention curve) highly affects both gas and heat transport parameters. In this study, the effects of water retention hysteresis (non-singularity in the wetting and drainage curves of soil-water retention) on the soil-gas diffusion coefficient (Dp), air permeability (ka), and thermal conductivity (K) were investigated. Different sand size fractions representing different particle shapes were used for measuring gas and heat transport parameters. Soil-water retention hysteresis highly affected the gas transport parameters, showing higher Dp and ka values for the wetting processes than those for drying processes at the same air content. This suggests that the existence of more continuous pore-networks for the wetting processes enhanced diffusive and advective gas transport. Opposite to the behavior of the gas transport parameters, the effect of soil water retention hysteresis on K was insignificant for all sand materials.
  埼玉大学研究機構科学分析支援センター, 日本語
  CiNii Articles ID：120005254400, CiNii Books ID：AA12504266
• 不飽和泥炭土のガス拡散係数の測定と予測モデルの構築・検証＜論文＞
  川本 健; 海野 将孝; 飯塚 健仁; 小松 登志子
  埼玉大学工学部紀要 第一部 論文集, 巻：42, 開始ページ：19, 終了ページ：24, 2008年
  The soil-gas diffusion coefficient (Dp) and its dependency on air-filled porosity (ε) govern the gas diffusion and reaction processes in soil. Accurate Dp(ε) prediction models for unsaturated saturated peat soils are needed to evaluate vadose zone transport and fate of greenhouse gases such as methane in peaty wetlands. In this study, we measured Dp on peat soil samples at different pF conditions, and developed new expressions for describing and predicting Dp(ε). Undisturbed peat soil samples were taken from Bibai wetland, Hokkaido, Japan. By modifying existing Dp(ε) models, the Buckingham model and the Macroporosity-Dependent model, we suggested two new Dp(ε) models for peat soils. To validate the new Dp(ε) models, we tested the models against independent datasets for peat soil samples from literatures. The modified Buckingham type model performed the best against independent datasets.
  埼玉大学工学部, 日本語
  CiNii Articles ID：120005373729
• 黒ぼく土カラムからの土壌コロイド流出解析
  川本 健; 斎藤 広隆; MOLDRUP Per; 小松 登志子
  埼玉大学工学部紀要 第一部 論文集, 巻：40, 開始ページ：28, 終了ページ：35, 2006年
  Transport of pesticides, heavy metal, radionuclide, and other strongly sorbing contaminants in soils is enhanced by colloid-facilitated transport. In order to understand colloid transport in soil, we first characterized coagulation/dispersion properties of colloidal solutions extracted from volcanic ash soil. Next, we investigated mobilization and leaching of colloidal materials from soil columns during rainfall irrigation. The coagulation/dispersion properties greatly varied with pH in colloidal solutions, causing change in particle size distributions with time. The leaching of colloids was numerically simulated using a new colloid transport model considering both equilibrium and kinetic sorption sites for colloids. HYDRUS-1D was used for the numerical simulation and estimation for transport parameters of colloids. The estimated distribution coefficient of natural colloids (which leached under application of artificial rainwater) was an order of magnitude larger than that of applied colloidal solution. The estimated detachment coefficient of natural colloids was three to four orders of magnitude greater than that of applied colloidal solution.
  埼玉大学工学部, 日本語
  CiNii Articles ID：120001370459

• Circular Economy and Waste Valorisation: Theory and Practice from an International Perspective　　　　　　　　　　　　　　　
  Giang, N.H.; T.T.V. Nga; T.T. Kien; N.H.Tan; K. Kawamoto, ［分担執筆］, A Circular Economy: Promotion of Construction and Demolition Waste Management in Vietnam
  Springer Nature, 2022年08月
  共同研究・競争的資金等ID：44511245
• Bifurcation and Localisation Theory in Geomechanics　　　　　　　　　　　　　　　
  Oda, M.; K. Suzuki; K. Kawamoto; K. Iwashita; S. Takahashi; H. Fujimori, ［分担執筆］, Micro-structural change during shearing and its contribution to the re-liquefaction phenomena of saturated granular soils under cyclic loading
  CRC Press, 2021年
• 土壌物理実験書　　　　　　　　　　　　　　　
  川本健, ［分担執筆］, 第I部 基礎編 実験2 土粒子の密度を測る－真比重，実験8 水の通りやすさを測る－飽和透水係数（変水頭法），第II部 応用編 実験17 ガス移動を測る－土壌ガス拡散係数と通気係数
  東京大学出版会, 2011年
• 改訂七版 農業農村工学ハンドブック　　　　　　　　　　　　　　　
  川本健, ［分担執筆］, 基礎編 第2部 土 1. 土壌・土壌物理 1.1.5 土壌空気
  社団法人農業農村工学会, 2010年
• 水再生利用学 －持続可能社会を支える水マネジメント　　　　　　　　　　　　　　　
  濱本昌一郎; 川本健; 小松登志子, ［共訳］, 第17章 再生水の農業利用
  技法堂出版, 2010年

• 科学技術外交の推進：持続可能なゼロエミッション社会形成の実現に向けて　　　　　　　　　　　　　　　
  川本 健
  R6年度埼玉大学研究機構戦略研究センター第一回公開シンポジウム, 2024年12月
  2024年12月 - 2024年12月, 日本語, 公開講演，セミナー，チュートリアル，講習，講義等
• Assessment of arsenic adsorption performance using calcinated laterite grains in fixed-bed column experiments for the water treatment　　　　　　　　　　　　　　　
  Bandara; I.M.N.N.; K. Nakamura; A. Matsuno; K. Kawamoto
  第21回地盤工学会関東支部発表会 (GeoKanto 2024), 2024年11月
  2024年11月 - 2024年11月, 英語, 口頭発表（一般）
• 顆粒状軽量気泡コンクリート(AAC)を混合した透水性舗装ブロックの蒸発性評価　　　　　　　　　　　　　　　
  坂井 優太; 中村 謙吾; 松野 晃大; 川本 健
  第21回地盤工学会関東支部発表会 (GeoKanto 2024), 2024年11月
  2024年11月 - 2024年11月, 日本語, 口頭発表（一般）
• ベトナム顆粒状ラテライトのヒ素吸脱着量にpHが及ぼす影響　　　　　　　　　　　　　　　
  藤﨑 鉄心; 中村 謙吾; 松野 晃大; 川本 健
  第21回地盤工学会関東支部発表会 (GeoKanto 2024), 2024年11月
  2024年11月 - 2024年11月, 日本語, 口頭発表（一般）
• Assessing the adaptability of urban water management through wetland-inspired filtration techniques: A review　　　　　　　　　　　　　　　
  Wijewardana, Y.N.S.; P. Gajanayake; L.W. Galagedara; K. Kawamoto
  The International Conference on Biomimicry for Sustainability (ICBS 2024), 2024年08月
  2024年08月 - 2024年08月, 英語, 口頭発表（一般）
• Removal of arsenic contaminated water by continuous column adoption using laterite grains as a low-cost adsorbent　　　　　　　　　　　　　　　
  Indraji Madhushan; Nayaka Bandara; I.M.N.; A. Matsuno; K. Nakamura; K. Kawamoto
  The 10th International Symposium on Advances in Civil and Environmental Engineering Practices for Sustainable Development (ACEPS2024), 2024年06月
  2024年06月 - 2024年06月, 英語, 口頭発表（一般）
• International technical cooperation project of construction and demolition waste (CDW) management and recycling in Vietnam　　　　　　　　　　　　　　　
  Kawamoto, K.
  The 10th International Symposium on Advances in Civil and Environmental Engineering Practices for Sustainable Development (ACEPS2024), 2024年06月, ［招待有り］
  2024年06月 - 2024年06月, 英語, 口頭発表（基調）
• ラテライト・熱処理ラテライトのヒ素吸着性の評価 ―バッチ試験・カラム試験から想定される試験方法による吸着性の違い―　　　　　　　　　　　　　　　
  中村 謙吾; 柳澤 龍太郎; N. Bandara; 松野 晃大; 川本 健
  第29回地下水・土壌汚染とその防止対策に関する研究集会, 2024年06月
  2024年06月 - 2024年06月, 日本語, ポスター発表
• Establishment of mutual technology for ground improvement and insolubilization of heavy metals by mixing Vietnamese coal ash and mud　　　　　　　　　　　　　　　
  Komori, I.; S. Uddin; A. Matsuno; K. Nakamura; K. Kawamoto
  Japanese Geoscience Union Meeting 2024, 2024年05月
  2024年05月 - 2024年05月, 英語, 口頭発表（一般）
• Evaluation of pH-dependent on arsenic adsorption and desorption process of laterite　　　　　　　　　　　　　　　
  Fujisaki, T.; K. Nakamura; K. Kawamoto; A. Matsuno
  Japanese Geoscience Union Meeting 2024, 2024年05月
  2024年05月 - 2024年05月, 英語, 口頭発表（一般）
• Comparative evaluation of evaporation efficiency of permeable pavement blocks made from recycled concrete and autoclaved aerated concrete at different design porosity　　　　　　　　　　　　　　　
  Sakai, Y.; S. Yanagisawa; A. Matsuno; K. Nakamura; K. Kawamoto
  Japanese Geoscience Union Meeting 2024, 2024年05月
  2024年05月 - 2024年05月, 英語, 口頭発表（一般）
• Evaluation of Adsorption performance of laterite soil for removal of arsenic from contaminated water bodies　　　　　　　　　　　　　　　
  Bandara; N.B.I.M.N.; R. Yanagisawa; A. Matsuno; K. Nakamura; K. Kawamoto
  Japanese Geoscience Union Meeting 2024, 2024年05月
  2024年05月 - 2024年05月, 英語, 口頭発表（一般）
• Thermal conductivity of recycled concrete aggregates blended with autoclaved aerated concrete grains　　　　　　　　　　　　　　　
  Pham, V.N.; A. Matsuno; K. Nakamura; K. Kawamoto
  Japanese Geoscience Union Meeting 2024, 2024年05月
  2024年05月 - 2024年05月, 英語, 口頭発表（一般）
• 荒川低地における原位置長期熱負荷・自然放冷試験中の浅層地下水の水質変化—Change in shallow groundwater quality during in-situ, long-term heating and natural cooling in Arakawa Lowland　　　　　　　　　　　　　　　
  杉江 瞭; 斎藤 健志; 川本 健; 小松 登志子
  地下水・土壌汚染とその防止対策に関する研究集会講演集, 2017年11月, [東京] : [地盤工学会]
  2017年11月 - 2017年11月, 日本語
• 埋立地最終覆土における降雨時のガス及び水移動　　　　　　　　　　　　　　　
  伊豆本聡; 濱本昌一郎; 井本博美; 川本健; 長森正尚; 西村拓
  地盤工学研究発表会発表講演集(CD-ROM), 2017年
  2017年 - 2017年
• 堆積環境の異なる地下帯水層における温度変化と水質変化の関係—Relationships between changes in subsurface temperature and groundwater quality in two confined aquifers with different sedimentary facies　　　　　　　　　　　　　　　
  斎藤 健志; 上島 雅人; 川本 健; 小松 登志子
  地下水・土壌汚染とその防止対策に関する研究集会講演集, 2016年06月, [東京] : [地盤工学会]
  2016年06月 - 2016年06月, 日本語
• 降雨中の浸潤に伴う土中空気圧変化とメタンガス噴出　　　　　　　　　　　　　　　
  伊豆本聡; 濱本昌一郎; 井本博美; 川本健; 西村拓
  農業農村工学会大会講演会講演要旨集(CD-ROM), 2016年
  2016年 - 2016年
• 温度変化が飽和多孔質体中の溶質移動特性に与える影響　　　　　　　　　　　　　　　
  有原萌恵; 濱本昌一郎; 川本健; 小松登志子
  地盤工学会関東支部発表会(CD-ROM), 2014年
  2014年 - 2014年
• 不飽和土壌の溶質・ガス拡散係数の統合的予測モデルの構築　　　　　　　　　　　　　　　
  濱本昌一郎; 川本健; 小松登志子; MOLDRUP Per
  農業農村工学会大会講演会講演要旨集(CD-ROM), 2014年
  2014年 - 2014年
• 地下水温変化が地下水質に与える影響　　　　　　　　　　　　　　　
  植木崇; 立石佳祐; 斉藤健志; 濱本昌一郎; 川本健; 小松登志子
  地下水・土壌汚染とその防止対策に関する研究集会講演集(CD-ROM), 2013年
  2013年 - 2013年
• 粒子形状・粒径・締固め度の違いが土壌の間隙構造および物質輸送係数に与える影響　　　　　　　　　　　　　　　
  小池拓也; 濱本昌一郎; 川本健; 小松登志子; 榊利博
  地下水・土壌汚染とその防止対策に関する研究集会講演集(CD-ROM), 2013年
  2013年 - 2013年
• 温度変化が地盤内の溶質分散特性に与える影響　　　　　　　　　　　　　　　
  有原萌恵; 濱本昌一郎; 濱本昌一郎; 川本健; 川本健; 小松登志子; 小松登志子
  地下水・土壌汚染とその防止対策に関する研究集会講演集(CD-ROM), 2013年
  2013年 - 2013年
• 異なる砂試料を用いたマイクロフォーカスX線CTによる間隙構造解析及び物質移動係数測定　　　　　　　　　　　　　　　
  小池拓也; 濱本昌一郎; 川本健; 小松登志子; 榊利博
  地盤工学研究発表会発表講演集(CD-ROM), 2013年
  2013年 - 2013年
• 砂質土の土壌水分ヒステリシスがガス・熱輸送係数に及ぼす影響　　　　　　　　　　　　　　　
  濱本昌一郎; 笹沼久美; 川本健; 榊利博; 小松登志子
  地盤工学研究発表会発表講演集(CD-ROM), 2013年
  2013年 - 2013年
• 二次圧密時の温度変化が粘土の圧密特性およびせん断剛性に与える影響　　　　　　　　　　　　　　　
  新屋陽理; MON Ei Ei; 濱本昌一郎; 川本健; 小松登志子
  地盤工学研究発表会発表講演集(CD-ROM), 2013年
  2013年 - 2013年
• 地盤内の溶質分散特性の温度依存性に関する研究　　　　　　　　　　　　　　　
  有原萌恵; 濱本昌一郎; 川本健; 小松登志子
  地盤工学会関東支部発表会(CD-ROM), 2013年
  2013年 - 2013年
• 温度変化が間隙水組成および土壌中重金属の存在形態に与える影響　　　　　　　　　　　　　　　
  栗原由衣; 濱本昌一郎; 濱本昌一郎; 川本健; 川本健; 小松登志子; 小松登志子
  地下水・土壌汚染とその防止対策に関する研究集会講演集(CD-ROM), 2013年
  2013年 - 2013年
• 美唄湿地の水・熱循環機構解明のためのシミュレーションおよび評価　　　　　　　　　　　　　　　
  稲葉薫; 川本健; 齊藤広隆; 濱本昌一郎; 小松登志子; 永田修
  日本地下水学会講演会講演要旨, 2013年
  2013年 - 2013年, 日本語
• 単粒・団粒構造を有する土壌の熱伝導特性:粒径および形状による影響　　　　　　　　　　　　　　　
  鴨志田剛久; 濱本昌一郎; 濱本昌一郎; 川本健; 川本健; 榊利博; 小松登志子; 小松登志子
  地下水・土壌汚染とその防止対策に関する研究集会講演集(CD-ROM), 2012年
  2012年 - 2012年
• 土壌撥水性曲線のモデル化と撥水性パラメータの評価　　　　　　　　　　　　　　　
  黒田卓也; SHAPHAL Subedi; 川本健; 平館俊太郎; MUEELLER Karin; 濱本昌一郎; 小松登志子
  地盤工学会関東支部発表会(CD-ROM), 2012年
  2012年 - 2012年
• 排水・吸水過程における不飽和砂質土のガス輸送係数　　　　　　　　　　　　　　　
  笹沼公美; 濱本昌一郎; 川本健; 榊利博; 小松登志子
  地盤工学会関東支部発表会(CD-ROM), 2012年
  2012年 - 2012年
• 砂の熱特性:土粒子の粒径・形状及び石英含有率による影響　　　　　　　　　　　　　　　
  鴨志田剛久; 濱本昌一郎; 川本健; 榊利博; 小松登志子
  地盤工学会関東支部発表会(CD-ROM), 2012年
  2012年 - 2012年
• 美唄湿地の水・熱循環機構解明のためのシミュレーション　　　　　　　　　　　　　　　
  稲葉薫; 川本健; 齊藤広隆; 濱本昌一郎; 小松登志子; 永田修
  日本地下水学会講演会講演要旨, 2012年
  2012年 - 2012年, 日本語
• 廃棄物処分場覆土におけるガス成分の分散特性　　　　　　　　　　　　　　　
  濱本昌一郎; 濱本昌一郎; 平野貴大; 川本健; 川本健; 小松登志子; 小松登志子
  地下水・土壌汚染とその防止対策に関する研究集会講演集(CD-ROM), 2011年
  2011年 - 2011年
• 異なる形状および粒径サイズを有する砂の熱移動に関する研究　　　　　　　　　　　　　　　
  鴨志田剛久; 濱本昌一郎; 川本健; 小松登志子
  地盤工学会関東支部発表会発表講演集, 2010年
  2010年 - 2010年
• 地盤内の物質・熱輸送係数の統合的予測式を用した処分場最終覆土層内のガス・熱輸送解析　　　　　　　　　　　　　　　
  濱本昌一郎; 川本健; 小松登志子; MOLDRUP Per
  地下水・土壌汚染とその防止対策に関する研究集会講演集(CD-ROM), 2010年
  2010年 - 2010年
• 国内土壌の透気係数測定と予測式の提案　　　　　　　　　　　　　　　
  杉本雄一; 濱本昌一郎; 飯塚健仁; 川本健; 小松登志子
  地下水・土壌汚染とその防止対策に関する研究集会講演集(CD-ROM), 2009年
  2009年 - 2009年
• 美唄湿地の水・熱循環機構解明のための基礎的数値モデルの構築　　　　　　　　　　　　　　　
  稲葉薫; 川本健; 齊藤広隆; 長谷川周一; 永田修
  日本地下水学会講演会講演要旨, 2009年
  2009年 - 2009年, 日本語
• Direct determination of water-table depths using multiple offset GPR profiling data in peatland　　　　　　　　　　　　　　　
  The Proceedings of 9th International Symposium for Environmental Issues in Korea and Japan, 2009年
• Direct determination of water-table depths using multiple offset GPR profiling data in peatland　　　　　　　　　　　　　　　
  The Proceedings of 9th International Symposium for Environmental Issues in Korea and Japan, 2009年
• 泥炭林土壌の温室効果ガスの濃度変化と放出　　　　　　　　　　　　　　　
  森本聡; 永田修; 川本健; 長谷川周一
  日本土壌肥料学会講演要旨集, 2008年09月
  2008年09月 - 2008年09月, 日本語
• 一次元カラム実験装置を用いた土壌ガス分散係数の測定　　　　　　　　　　　　　　　
  濱本昌一郎; 川本健; 小松登志子
  地下水・土壌汚染とその防止対策に関する研究集会講演集(CD-ROM), 2008年
  2008年 - 2008年
• 原位置試験を用いた土壌透気係数の評価　　　　　　　　　　　　　　　
  杉本雄一; 濱本昌一郎; 川本健; 小松登志子
  地下水・土壌汚染とその防止対策に関する研究集会講演集(CD-ROM), 2008年
  2008年 - 2008年
• 砂と団粒土のガス分散長に関する研究　　　　　　　　　　　　　　　
  濱本昌一郎; 川本健; 小松登志子
  土壌物理学会講演要旨集, 2008年
  2008年 - 2008年
• Characterizing soil water repellency properties by soil organic carbon content, soil texture and sieved-size fractions　　　　　　　　　　　　　　　
  Interfaces Against Pollution 2008, 2008年
  2008年 - 2008年
• The effect of soil compaction on solute diffusion in volcanic ash soil　　　　　　　　　　　　　　　
  Interfaces Against Pollution 2008, 2008年
  2008年 - 2008年, ポスター発表
• Transport and straining of colloid-sized materials in saturated porous media　　　　　　　　　　　　　　　
  Interfaces Against Pollution 2008, 2008年
  2008年 - 2008年, ポスター発表
• 泥炭林土壌でのCO₂・CH₄の生成と放出　　　　　　　　　　　　　　　
  森本聡; 長谷川周一; 永田修; 川本健
  農業農村工学会北海道支部研究発表会講演集, 2008年
  2008年 - 2008年, 日本語
• Gas diffusion coefficient in variably saturated peat soil: Development and tests of predictive models　　　　　　　　　　　　　　　
  American Geophysical Union Fall Meeting 2008, 2008年
  ポスター発表
• Three-dimensional pore structure analysis for peat materials using microfocus X-ray computed tomography　　　　　　　　　　　　　　　
  American Geophysical Union Fall Meeting 2008, 2008年
  ポスター発表
• Irreversibility of 2,4-dichlorophenoxyacetic acid sorption onto a volcanic ash soil : Effect of pH　　　　　　　　　　　　　　　
  American Geophysical Union Fall Meeting 2008, 2008年
  ポスター発表
• Single- and two-individual-region models for gas diffusivity in structureless or aggregated, unsaturated soil　　　　　　　　　　　　　　　
  S-1 Division, 2008 ASA-CSSA-SSSA International Annual Meetings, 2008年
  ポスター発表
• Development of a predictive expression for soil water repellency based on soil organic carbon content　　　　　　　　　　　　　　　
  S-1 Division, 2008 ASA-CSSA-SSSA International Annual Meetings, 2008年
  ポスター発表
• Simultaneous measurements of the soil-gas dispersion coefficient, gas permeability, and gas diffusivity in repacked, structureless and aggregated soils　　　　　　　　　　　　　　　
  S-1 Division, 2008 ASA-CSSA-SSSA International Annual Meetings, 2008年
  ポスター発表
• Transport and straining of colloid-sized materials in saturated porous media: Experimental and numerical analysis　　　　　　　　　　　　　　　
  S-1 Division, 2008 ASA-CSSA-SSSA International Annual Meetings, 2008年
  ポスター発表
• Measurement of gas transport parameters for peat soils: Effect of volume shrinkage with successive drainage　　　　　　　　　　　　　　　
  International Symposium on Environmental Management: Hazardous-Environmental Management Toward Sustainability (iSEM 2008), 2008年
• Spatial variability and scale dependency of soil-air permeability at waste disposal landfill site and natural field　　　　　　　　　　　　　　　
  International Symposium on Environmental Management: Hazardous-Environmental Management Toward Sustainability (iSEM 2008), 2008年
• Sorption and desorption behavior of 2,4-dichlorophenoxyacetic acid in kaolinite, volcanic ash soil and water dispersible colloid　　　　　　　　　　　　　　　
  International Symposium on Environmental Management: Hazardous-Environmental Management Toward Sustainability (iSEM 2008), 2008年
• Measurements of the soil-gas dispersion coefficient, gas permeability, and gas diffusivity in repacked structureless and aggregated soils: Effect of soil structure, particle size and column scale　　　　　　　　　　　　　　　
  International Symposium on Environmental Management: Hazardous-Environmental Management Toward Sustainability (iSEM 2008), 2008年
• Scale dependency of gas transport parameters in undisturbed soils　　　　　　　　　　　　　　　
  Japanese Geoscience Union Meeting 2008, 2008年
  ポスター発表
• Comparison of solute diffusivity between volcanic ash soils and normal mineral soils　　　　　　　　　　　　　　　
  Japanese Geoscience Union Meeting 2008, 2008年
  ポスター発表
• Measurements of gas phase convection and dispersion parameters in soil　　　　　　　　　　　　　　　
  Japanese Geoscience Union Meeting 2008, 2008年
  ポスター発表
• Experimental and numerical analysis of colloid transport and straining in saturated sand　　　　　　　　　　　　　　　
  Japanese Geoscience Union Meeting 2008, 2008年
• Gas transport parameters for peat soils at near saturated condition　　　　　　　　　　　　　　　
  Proceedings of the International Exchange Symposium on Sustainable Infrastructure Development in Asia, 2008年
• Spatial variability and scale dependency of soil-air permeability in a landfill soil cover and three natural field soils　　　　　　　　　　　　　　　
  Proceedings of the International Exchange Symposium on Sustainable Infrastructure Development in Asia, 2008年
• Emerging aspects of soil hydrology: Soil water repellency, fingered flow, and high resolution measurement methods　　　　　　　　　　　　　　　
  Proceedings of the International Exchange Symposium on Sustainable Infrastructure Development in Asia, 2008年
• Development of a predictive expression for soil water repellency curve based on soil organic carbon content　　　　　　　　　　　　　　　
  Proceedings on the Third HYDRUS Workshop, 2008年
  ポスター発表
• Measurements of distribution coefficients for pesticide onto soil and colloidal materials　　　　　　　　　　　　　　　
  Proceedings of the International Exchange Symposium on Sustainable Infrastructure Development in Asia, 2008年
• Transport and retention of colloid-sized materials in saturated porous media: Experimental and numerical analysis　　　　　　　　　　　　　　　
  Proceedings on the Third HYDRUS Workshop, 2008年
  ポスター発表
• Gas diffusion coefficient in variably saturated peat soil: Development and tests of predictive models　　　　　　　　　　　　　　　
  American Geophysical Union Fall Meeting 2008, 2008年
  ポスター発表
• Three-dimensional pore structure analysis for peat materials using microfocus X-ray computed tomography　　　　　　　　　　　　　　　
  American Geophysical Union Fall Meeting 2008, 2008年
  ポスター発表
• Irreversibility of 2,4-dichlorophenoxyacetic acid sorption onto a volcanic ash soil : Effect of pH　　　　　　　　　　　　　　　
  American Geophysical Union Fall Meeting 2008, 2008年
  ポスター発表
• Single- and two-individual-region models for gas diffusivity in structureless or aggregated, unsaturated soil　　　　　　　　　　　　　　　
  S-1 Division, 2008 ASA-CSSA-SSSA International Annual Meetings, 2008年
  ポスター発表
• Development of a predictive expression for soil water repellency based on soil organic carbon content　　　　　　　　　　　　　　　
  S-1 Division, 2008 ASA-CSSA-SSSA International Annual Meetings, 2008年
  ポスター発表
• Simultaneous measurements of the soil-gas dispersion coefficient, gas permeability, and gas diffusivity in repacked, structureless and aggregated soils　　　　　　　　　　　　　　　
  S-1 Division, 2008 ASA-CSSA-SSSA International Annual Meetings, 2008年
  ポスター発表
• Transport and straining of colloid-sized materials in saturated porous media: Experimental and numerical analysis　　　　　　　　　　　　　　　
  S-1 Division, 2008 ASA-CSSA-SSSA International Annual Meetings, 2008年
  ポスター発表
• Measurement of gas transport parameters for peat soils: Effect of volume shrinkage with successive drainage　　　　　　　　　　　　　　　
  International Symposium on Environmental Management: Hazardous-Environmental Management Toward Sustainability (iSEM 2008), 2008年
• Spatial variability and scale dependency of soil-air permeability at waste disposal landfill site and natural field　　　　　　　　　　　　　　　
  International Symposium on Environmental Management: Hazardous-Environmental Management Toward Sustainability (iSEM 2008), 2008年
• Sorption and desorption behavior of 2,4-dichlorophenoxyacetic acid in kaolinite, volcanic ash soil and water dispersible colloid　　　　　　　　　　　　　　　
  International Symposium on Environmental Management: Hazardous-Environmental Management Toward Sustainability (iSEM 2008), 2008年
• Measurements of the soil-gas dispersion coefficient, gas permeability, and gas diffusivity in repacked structureless and aggregated soils: Effect of soil structure, particle size and column scale　　　　　　　　　　　　　　　
  International Symposium on Environmental Management: Hazardous-Environmental Management Toward Sustainability (iSEM 2008), 2008年
• Scale dependency of gas transport parameters in undisturbed soils　　　　　　　　　　　　　　　
  Japanese Geoscience Union Meeting 2008, 2008年
  ポスター発表
• Comparison of solute diffusivity between volcanic ash soils and normal mineral soils　　　　　　　　　　　　　　　
  Japanese Geoscience Union Meeting 2008, 2008年
  ポスター発表
• Measurements of gas phase convection and dispersion parameters in soil　　　　　　　　　　　　　　　
  Japanese Geoscience Union Meeting 2008, 2008年
  ポスター発表
• Experimental and numerical analysis of colloid transport and straining in saturated sand　　　　　　　　　　　　　　　
  Japanese Geoscience Union Meeting 2008, 2008年
• Gas transport parameters for peat soils at near saturated condition　　　　　　　　　　　　　　　
  Proceedings of the International Exchange Symposium on Sustainable Infrastructure Development in Asia, 2008年
• Spatial variability and scale dependency of soil-air permeability in a landfill soil cover and three natural field soils　　　　　　　　　　　　　　　
  Proceedings of the International Exchange Symposium on Sustainable Infrastructure Development in Asia, 2008年
• Emerging aspects of soil hydrology: Soil water repellency, fingered flow, and high resolution measurement methods　　　　　　　　　　　　　　　
  Proceedings of the International Exchange Symposium on Sustainable Infrastructure Development in Asia, 2008年
• Development of a predictive expression for soil water repellency curve based on soil organic carbon content　　　　　　　　　　　　　　　
  Proceedings on the Third HYDRUS Workshop, 2008年
  ポスター発表
• Measurements of distribution coefficients for pesticide onto soil and colloidal materials　　　　　　　　　　　　　　　
  Proceedings of the International Exchange Symposium on Sustainable Infrastructure Development in Asia, 2008年
• Transport and retention of colloid-sized materials in saturated porous media: Experimental and numerical analysis　　　　　　　　　　　　　　　
  Proceedings on the Third HYDRUS Workshop, 2008年
  ポスター発表
• 土壌の構造および粒径がガス拡散係数に及ぼす影響　　　　　　　　　　　　　　　
  杉本雄一; 濱本昌一郎; 長谷川久展; 川本健; 小松登志子
  土壌物理学会講演要旨集, 2007年
  2007年 - 2007年
• 人工マクロポアを含む砂のガス輸送パラメータへの毛管束モデルの適用　　　　　　　　　　　　　　　
  濱本昌一郎; 川本健; 小松登志子
  土壌物理学会講演要旨集, 2007年
  2007年 - 2007年
• Modeling of laterally expanding fingering flow in sandy soils　　　　　　　　　　　　　　　
  Proceedings of the 2nd Asian Conference on Unsaturated Soils, UNSAT-ASIA 2003, 2003年
• Modeling of laterally expanding fingering flow in sandy soils　　　　　　　　　　　　　　　
  Proceedings of the 2nd Asian Conference on Unsaturated Soils, UNSAT-ASIA 2003, 2003年
• Micro-structural change during shearing and its contribution to the re-liquefaction phenomena of saturated granular soils under cyclic loading　　　　　　　　　　　　　　　
  5th International Workshop on Bifurcation and Localisation Theory in Geomechanics, The, 2001年
• Micro-structural change during shearing and its contribution to the re-liquefaction phenomena of saturated granular soils under cyclic loading　　　　　　　　　　　　　　　
  5th International Workshop on Bifurcation and Localisation Theory in Geomechanics, The, 2001年
• フィンガー流の形態による塩分溶脱効果の相違.　　　　　　　　　　　　　　　
  川本健
  農業土木学会論文集, 1996年
  1996年 - 1996年

• 2016年04月 - 現在
  Environmental Geotechnical Engineering, 埼玉大学, 大学院専門科目
• 2013年 - 現在
  地盤環境工学, 埼玉大学, 学部専門科目
• 2007年 - 現在
  地盤環境工学特論(E), 埼玉大学, 大学院専門科目
• 2007年 - 2012年
  地盤工学Ⅰ, 埼玉大学, 学部専門科目

• 土壌物理学会
• 土木学会
• 地盤工学会
• 廃棄物資源循環学会

• ベトナムにおける廃棄物処分場環境汚染防止のための適正技術開発　　　　　　　　　　　　　　　
  国立研究開発法人 科学技術振興機構, さくら招へいプログラム, A. 科学技術体験コース, 2025年02月 - 2025年02月
  埼玉大学、ダナン工科大学, 研究代表者
  配分額（総額）：1528540
• ベトナムにおける重金属含有泥土の地盤改良・浄化に向けた石炭灰有効利用　　　　　　　　　　　　　　　
  日本学術振興会, ベトナムとの共同研究(MOST), 2022年04月 - 2024年03月
  埼玉大学、ハノイ国立建設大学, 研究代表者
  配分額（総額）：5000000
• ベトナムにおける建設廃棄物の適正管理と建廃リサイクル資材を活用した環境浄化及びインフラ整備技術の開発　　　　　　　　　　　　　　　
  科学技術振興機構, 国際的な科学技術共同研究などの推進 SATREPS, 2017年 - 2024年
  川本 健(研究代表)、他, 埼玉大学, 研究代表者
  建設廃棄物の適正管理とリサイクルを推進! 新たな技術開発も! ベトナムをはじめとするアジア都市域では開発にともなう建設廃棄物の発生量が急増している。本研究では、ベトナムにおける建設廃棄物の適正管理とリサイクルを推進するため、建廃取扱いガイドラインやリサイクル資材の品質基準を整備し、リサイクル資材を活用した技術開発(水質浄化や透水性路盤)を進める。さらに、リサイクル推進のための戦略的ビジネスモデルを提案し、現地での試験的事業によりその有効性を検証する。ベトナム国家戦略達成を可能とする資源循環システムの構築へ 建設廃棄物の適正管理とリサイクルのための資源循環システムの基盤がハノイ市で構築されるとともに、開発された技術やビジネスモデルが実際の事業に適用されることを通じて、ベトナム国家戦略の2025年数値目標である建廃リサイクル率50%達成に貢献することを目指す。
  論文ID：49522070, 書籍等出版物ID：49539139, 受賞ID：49140852, 社会貢献活動ID：49528046, メディア報道ID：49527087
• 微視的構造解析に基づくベントナイトの物質移動係数のモデル化　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2017年04月01日 - 2020年03月31日
  川本 健, 埼玉大学
  配分額（総額）：17680000, 配分額（直接経費）：13600000, 配分額（間接経費）：4080000
  放射性廃棄物地層処分において廃棄物収納容器と周辺地盤の間を充填する材料として、ベントナイトの利用が検討されている。本研究では異なる相対湿度・充填密度条件の顆粒状及びブロック状ベントナイトを用いて、マイクロフォーカスX線CTを用いた微視的構造観察、物質移動係数を評価し、その数理モデル構築を試みた。その結果、ベントナイト内部均質化は細粒・粗粒分比率で定量的に評価でき、顆粒状ベントナイトのガス拡散係数・通気係数は、有効気相率を考慮した予測モデルで上手く表現できること等が明らかとなった。これらの知見は、放射性廃棄物地層処分における充填材内部の物質動態評価や長期安定性評価に活用されることが期待される。
  課題番号：17H03301
  論文ID：49528747
• 微細間隙構造と地下水流れを考慮した堆積岩の凍結挙動の定量的な評価手法の開発　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 基盤研究(A), 2014年04月01日 - 2019年03月31日
  山辺 正; 長田 昌彦; 竹村 貴人; 川本 健; 浅本 晋吾; 竹内 真司; 橘 伸也; 渡邉 邦夫, 埼玉大学
  配分額（総額）：30680000, 配分額（直接経費）：23600000, 配分額（間接経費）：7080000
  低温環境に置かれた岩質材料の伝熱特性について検討した．供試体レベルの冷却試験では直径50 mm高さ50 mm の円柱供試体と，直径50 mm および100 mm の球状供試体を用いた．実験では中心と側面において時間経過に伴う温度変化を計測した．解析では円柱および球状供試体の冷却試験に厳密解を適用し，熱伝達境界を適切に設定することにより伝熱特性を精度良く表現できた．さらに数値解析においても０℃付近で温度低下が停留する状況を再現することが出来た．また，凍結管周辺の流れ挙動を室内実験により検討し，凍結領域が進展する様子を可視化することに成功した．これらの成果を実地盤に適用することが期待される．
  課題番号：26249068
• スリランカ廃棄物処分場における地域特性を活かした汚染防止と修復技術の構築　　　　　　　　　　　　　　　
  科学技術振興機構, 国際的な科学技術共同研究などの推進 SATREPS, 2010年 - 2015年
  田中 規夫、川本 健(主研究取組者)、他, 埼玉大学
  その国の実情や特徴に合わせた廃棄物処分場汚染防止策を検討する 近年、開発途上国では廃棄物排出量が増加し、深刻な社会・環境問題を引き起こしている。スリランカも廃棄物問題に悩む国の一つであり、廃棄物処分場とその周辺域で健康被害や環境劣化が急速に進行している。本課題では、スリランカ廃棄物処分場における環境汚染防止技術や安全な修復技術の構築に挑んでいる。これらの技術には、地域で入手が容易な土材料やココヤシ等のバイオ材料を活用し、低コスト・低メンテナンスで、持続可能な技術確立を目指す。この技術をもとに処分場の計画・管理・汚染防止ガイドを作成し、廃棄物問題解決に貢献する。 持続可能な汚染防止技術を確立・活用、野外スケール研究の実施も 対象処分場の土壌・地下水汚染の調査、地方自治体の廃棄物管理事業調査を行っている。次のステップとして、これらの調査結果を踏まえて、低コストかつ持続可能な廃棄物処分場の汚染防止・修復技術開発を行い、これらの技術を活用した野外スケール研究を実施し、廃棄物処分場を設計する際のガイドをスリランカ関連省と共同で作成する。
  論文ID：49528657, 受賞ID：49141671
• 土壌ガス挙動のモデル化と環境リスク評価への適用　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2006年 - 2008年
  小松 登志子; 川本 健; 長谷川 周一; 溝口 勝, 埼玉大学
  配分額（総額）：15150000, 配分額（直接経費）：14100000, 配分額（間接経費）：1050000
  本研究では, 環境リスク評価に適用できる統合モデルの構築を目指して, 土壌内におけるガスの挙動を測定し, ガス挙動に与える土壌特性の影響を調べるとともに, トランスポート・パラメータ(拡散係数, 分散係数, 通気係数, 溶質拡散係数)のモデル化を行った. 土壌ガスのトランスポート・パラメータについては, 火山灰土壌, 砂質土を用いて実測を行い, 間隙構造や粒径分布, 有機物含有量などの土壌特性を考慮した多くの新しい予測モデルを提案した. 従来のモデルの検証も行った. また, 同一カラムで3つの土壌ガスのトランスポート・パラメータ(拡散係数, 分散係数, 通気係数)を測定できる新しい方法を開発した. 構造異方性のある泥炭土の乾燥過程におけるガス拡散係数, 通気係数を測定し, 泥炭土のガス輸送機構は泥炭の内間隙と外間隙の水分状態に応じて大きく3つに区分されることが示唆された. 溶質拡散についてはこれまでに報告例の少ない火山灰土壌の拡散係数を測定し, 火山灰土壌は団粒内間隙と団粒間間隙という複雑な土壌構造を持つため, 拡散係数が他の土壌に比べて特異な挙動を示すことがわかった. 土壌特性(粘土, 有機物含有量)と土壌構造(間隙径分布)を考慮した新しい溶質拡散係数の予測モデルも提案した. このように多くの実測とともに, 最終目標とする統合モデルの構築の基盤となる多くの簡便で正確な予測モデルを提案した.
  課題番号：18360224
  論文ID：24337889
• 汚染物質のコロイド形態による土壌内移動と運命予測の解明　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 若手研究(A), 2006年 - 2008年
  川本 健; 斎藤 広隆; MOLDRUP; 小松 登志子, 埼玉大学
  配分額（総額）：19110000, 配分額（直接経費）：14700000, 配分額（間接経費）：4410000
  現在,土壌・地下水汚染問題が国内外で顕在化している。本研究では,汚染物質を吸着して地盤内を長距離まで移動することが報告されている土壌コロイド(粒径が1μm以下)に注目し,土壌内での移動挙動解析や汚染物質(農薬や鉛)の吸着特性を,室内実験を中心に検討した。その結果,多孔質媒体内での土壌コロイドの移動特性は各付着係数を考慮した移流分散式で上手く表現できること等の成果が得られ,これらの成果は汚染物質のコロイド担体輸送が関与する諸問題(汚染領域の特定や汚染土壌の効率的な浄化工法の構築)に寄与するものと言える。
  課題番号：18686039
• 粒状体の準静的流れから高速流れへの移行に関する基礎的研究　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2004年 - 2006年
  小田 匡寛; 岩下 和義; 岸野 佑次; 鈴木 輝一; 風間 秀彦; 川本 健, 埼玉大学
  配分額（総額）：11500000, 配分額（直接経費）：11500000
  土構造物は、壊れてはならないとの前提で設計される。しかし現実には、土構造物の基礎地盤の破壊は毎年繰り返され、流れる土砂は土木構造物に大きな被害を及ぼし続けている。この事実は、破壊後の土の挙動がいかに重要であるかを示している。土の破壊は、せん断帯に沿う準静的な滑りから始まり、条件によっては高速な流れへと移行する。この移行現象は、土石流の制御や被害の軽減を考えなければならない技術者にとって、きわめて緊急かっ重要な課題であると言わざるを得ない。本年度は、二次元せん断装置を使った室内実験と数値シミュレーションを行い、準静的から高速までの流動特性について検討し、次の結果を得た。
  1)2次元のせん断流れ実験装置により、高速流れにある粒子を高速ビデオの画像を処理することによって追跡し、粒子移動・回転を高精度に捉え、粒状温度分布、粒子密度分布、速度分布、速度勾配を量的に把握した。この実験成果を、数値シミュレーション結果、理論的な予測と照合することによって、粒子レベルでの静的流れから高速流れへの移行機構について明らかにした。
  2)マイクロフォカスX-線CTにより3次元で静的せん断帯の構造変化を観察することにより、その粒子レベルでの流動メカニズムを解明した。また、準静的流れにある粒状体の微視的構造を数量化する一般的な手法を提案した。
  3)個別要素法(DEM)により、準静的から高速流れへの移行を数値解析的にシミュレーションし、物理実験との定性的な一致を確認した。また、水との練成を考慮した数値解析的にシミュレーションの有効性が確認できたので、今後、液相の効果を考慮した高速流れへの移行問題を数値的に解明する予定である。
  課題番号：16360233
• 選択流の形態による水・コロイド・汚染物質同時輸送機構の解明　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 若手研究(B), 2005年 - 2005年
  川本 健, 埼玉大学
  配分額（総額）：3000000, 配分額（直接経費）：3000000
  課題番号：17760386
  論文ID：27643536
• 森林土壌における選択的水みちを考慮した水移動に関する研究　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 若手研究(B), 2002年 - 2003年
  川本 健, 埼玉大学
  配分額（総額）：2800000, 配分額（直接経費）：2800000
  本研究は、集中豪雨にともなう斜面崩壊が発生した福島県内の森林丘陵サイトを選定し、原位置調査・試験、長期にわたる原位置計測、採取試料を用いた室内試験を行い、以下の二つについての研究を行った。
  1)現地計測と室内試験の組み合わせによる選択流形成の実態把握
  2)森林土壌における選択流発生メカニズムの解明
  1)に関しては、現地計測データと室内試験から求めた不飽和透水係数、水分特性曲線を比較することにより、原位置の透水性に及ぼす選択流の影響を調べた。この成果は、第38回地盤工学研究発表会(H15年6月)にて発表し、「Preferential Flow Effect on Soil Water Dynamics in a Forested Volcanic Ash Soil」と題して、Journal of Hydrologyに投稿中である。
  2)に関しては、森林土壌における選択流発生の要因として表土の土壌撥水性に注目し、その発現条件、発現度合いに土壌の初期水分量や有機物含有量が及ぼす影響を調べた。この成果を平成15年度農業土木学会大会講演会や第45回土壌物理学会シンポジウムに発表するとともに、農業土木学会論文集に、「火山灰土壌の撥水性評価に関する研究-有機物含有量と初期水分量が及ぼす影響-(印刷中)」にて報告した。さらに、選択流の発生メカニズムの解明、成長モデル構築の基礎として、砂質土壌を用いた室内実験を行い、選択流(フィンガー流)の膨張メカニズムを明らかにした。この成果をGeodermaに、「Moisture Structures of Laterally Expanding Fingering Flows in Sandy Soils (2004)」と題して報告した。
  課題番号：14750410
  論文ID：24337884, 受賞ID：49141607
• マイクロメカニックスの手法による砂の液状化機構解明に関する実験的研究　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2000年 - 2002年
  小田 匡寛; 中瀬 仁; 岩下 和義; 鈴木 輝一; 川本 建; 風間 秀彦, 埼玉大学
  配分額（総額）：7800000, 配分額（直接経費）：7800000
  平成12〜14年度の研究は、1)水との連成を考慮した液状化解析用個別要素法プログラム(DEM)を開発し、その結果を使って、2)流動化のメカニズムを粒子レベルで解明し、流動化に及ぼす種々の影響因子を具体的に解明することにある。また、解析用プログラムの信頼性を確認する日的で、3)浸透流による地盤の破壊現象を室内実験と数値実験の両面から検討した。その研究経過を要約すれば以下の通りである。
  1)水との連成を考慮した液状化解析用個別要素法プログラムの開発(鈴木、田中、中瀬):浸透流に伴う地盤のパイピング破壊現象を室内実験と数値実験の両面から検討し、数値解析結果は現象を定性的に再現する事が確認された。現在、この成果を論文として取りまとめ、土木学会の論文集に投稿の予定である。
  2)DEMによる数値実験(岸下、小田):DEMにより、体積一定下で繰返しのせん断の数値実験を行い、液状化に至る構造変化をファブリックテンソル、ループテンソルで漸し、流動化の微視的機構について検討した。更に、得られた成果を高速流れの問題への拡張を図るために、室内実験と数値シミュレーションを行った。その成果を論文として取りまとめ、土木学会の論文集に投稿中である。
  3)非排水繰返しせん断試験による液状化実験(小田、川本):豊浦砂・成田砂・真砂土を試料とした非排水繰返し三軸試験を行い、液状化強度に及ぼす初期構造異方性、不均質、誘導構造異方性、粒度組成の影響を検討した。またマイクロフォーカスX線CTにより、液状化供試体の土粒子の構造を解析した。その成果の一部は、ASCEに発表した。
  課題番号：12450187
  論文ID：24337875

• Editorial board member, Journal of Science and Technology in Civil Engineering (STCE)　　　　　　　　　　　　　　　
  監修, 査読
  2021年01月01日 - 現在
  学会・研究会等
• Scientific Committee Member, The International Conference on Resource Efficiency Towards Sustainability (ICRES 2025)　　　　　　　　　　　　　　　
  企画立案・運営等
  GAP HQ, Sri Lanka, 2025年03月06日 - 2025年03月06日
  学会・研究会等
• Co-organizer, The 10th International Symposium on Advances in Civil and Environmental Engineering Practices for Sustainable Development (ACEPS2024)　　　　　　　　　　　　　　　
  企画立案・運営等, パネル司会・セッションチェア等
  Ruhuna University, Sri Lanka and Saitama University, Japan, 2024年06月27日 - 2024年06月27日
  大会・シンポジウム等
• 地下水・土壌汚染とその防止対策に関する研究集会 幹事　　　　　　　　　　　　　　　
  企画立案・運営等, 査読
  土壌環境センター, 2008年 - 2021年
  大会・シンポジウム等
• 第26回地下水・土壌汚染とその防止対策に関する研究集会 実行委員長　　　　　　　　　　　　　　　
  企画立案・運営等
  土壌環境センター, 2021年
  大会・シンポジウム等
• Soils and Foundations, Executive board member　　　　　　　　　　　　　　　
  監修, 査読
  地盤工学会, 2016年04月 - 2019年08月
  学会・研究会等
• 関東支部委員 埼玉県グループ リーダー幹事　　　　　　　　　　　　　　　
  企画立案・運営等
  地盤工学会, 2014年 - 2019年
  学会・研究会等
• International Advisory Committee, Conference on Sri Lanka Japan Collaborative Research 2013 (SLJCR-2013)　　　　　　　　　　　　　　　
  企画立案・運営等, パネル司会・セッションチェア等
  University of Peradeniya, Sri Lanka, 2013年03月
• 第18回地下水・土壌汚染とその防止対策に関する研究集会 幹事長　　　　　　　　　　　　　　　
  企画立案・運営等
  土壌環境センター, 2011年
  大会・シンポジウム等
• 調査研究部門 コンクリート委員会 コンクリート－地盤協会問題研究小委員会委員　　　　　　　　　　　　　　　
  企画立案・運営等, 監修
  土木学会, 2008年10月 - 2010年06月
  学会・研究会等
• JSPS Asia Africa Science Platform Program Joint seminar on “Innovative vegetation bio-engineering approaches for water quality improvement and disaster mitigation”, Committee Member　　　　　　　　　　　　　　　
  企画立案・運営等
  日本学術振興会, 2010年05月
  大会・シンポジウム等
• 論文集編集委員　　　　　　　　　　　　　　　
  企画立案・運営等, 査読
  土壌物理学会, 2007年04月01日 - 2010年03月31日
  査読等
• 関東支部委員 埼玉県グループ リーダー幹事　　　　　　　　　　　　　　　
  企画立案・運営等
  地盤工学会, 2004年05月 - 2009年10月
  学会・研究会等
• 論文集編集委員　　　　　　　　　　　　　　　
  企画立案・運営等, 査読
  農業土木学会, 2004年06月 - 2008年05月
  学会・研究会等
• 国内委員会実行委員　　　　　　　　　　　　　　　
  企画立案・運営等, パネル司会・セッションチェア等
  Interface Against Pollution 2008, 2008年
  大会・シンポジウム等
• 「土壌の物理性」100号記念準備委員会委員　　　　　　　　　　　　　　　
  企画立案・運営等, 査読
  土壌物理学会, 2004年10月
  学会・研究会等
• The Sixth International Summer Symposium Committee Member　　　　　　　　　　　　　　　
  企画立案・運営等, 査読
  土木学会, 2004年07月
  学会・研究会等
• 「土と基礎」会誌部委員, 編集委員会 企画担当グループ主査　　　　　　　　　　　　　　　
  企画立案・運営等, 査読
  地盤工学会, 2002年06月 - 2004年06月
  学会・研究会等
• 「土と基礎」編集委員会 企画担当グループ委員　　　　　　　　　　　　　　　
  企画立案・運営等, 査読
  地盤工学会, 2000年06月 - 2001年06月
  学会・研究会等

• ダナン工科大学とJSTさくらサイエンスプログラムを実施しました　　　　　　　　　　　　　　　
  埼玉大学Webニュース, https://www.saitama-u.ac.jp/topics_archives/202503051400.html, 2025年03月05日, ［インターネットメディア］