日本地球惑星科学連合2014年大会

講演情報

インターナショナルセッション(ポスター発表)

セッション記号 A (大気海洋・環境科学) » A-GE 地質環境・土壌環境

[A-GE03_30PO1] Subsurface Mass Transport and Environmental Assessment

2014年4月30日(水) 14:00 〜 15:15 3階ポスター会場 (3F)

コンビーナ:*森 也寸志(岡山大学大学院環境生命科学研究科)、斎藤 広隆(東京農工大学大学院農学研究院)、川本 健(埼玉大学大学院理工学研究科)、濱本 昌一郎(東京大学大学院農学生命科学研究科)、張 銘(産業技術総合研究所地圏資源環境研究部門)

14:00 〜 15:15

[AGE03-P03] Characterization of water repellency parameters in soil water repellency characteristic curves for JP and NZ soils

*WIJEWARDANA Senani1KAWAMOTO Ken1MULLER Karin2CLOTHIER Brent3HIRADATE Syuntaro4KOMATSU Toshiko1MOLDRUP Per5 (1.Graduate School of Science and Engineering, Saitama University, Japan、2.Plant & Food Research Institute, Ruakura Research Centre, New Zealand、3.Plant & Food Research Institute, Palmerston North, New Zealand、4.Biodiversity Division, National Institute for Agro-Environmental Sciences (NIAES) Japan、5.Department of Civil Engineering, Aalborg University, Denmark)

キーワード:soil water repellency characteristic curve, water repellency parameters, soil organic carbon

Soil water repellency (SWR) is the phenomenon where soil does not wet when water is applied to its surface. Characterization of water repellency in natural soil is very important to understand the soil hydrological processes, surface flow and infiltration rates. Objectives of this study were (i) to characterize SWR using molarity of ethanol droplet (MED) test, sessile drop method (SDM) and water drop penetration time (WDPT) test, and (ii) to identify the relationships between the determined SWR parameters and soil organic carbon (SOC) contents. Soil samples were collected from different soil depths of representative Andosols and Cambisols in Japan (Nishigo, Hiruzen and Nikko; all sites under forest) and New Zealand (Ngahinapouri, Wahihora and Whatawhata; all sites under pasture). The soil-water contact angle was directly measured using SDM, and indirectly derived from MED and WDPT measurements. All the A horizons of the Japanese soils showed water repellency, and the New Zealand soils were also water repellent at all depths except the Ngahinapouri, B horizon. Then, soil water repellency characteristic curves (SWRCCs) were obtained for water repellent (WR) soils, i.e., soil-water contact angle / degree of WR as a function of the volumetric water content (θ). Three WR parameters were determined from the SWRCCs. They are (i) the integrated areas below a SWRCC, SWR(θ), (ii) the soil water content at maximum (θWR-Max) and (iii) minimum (θWR-Min) WR. Further, WR parameters were studied with soil organic carbon (SOC) contents. These relationships were agreed well with recently published work of Kawamoto et al. (2007) and Karunarathna et al. (2010). The SOC contents of New Zealand soils varied between 1.4% (WR) to 12.1% (WR), for the Japanese soils they ranged between 2.6% (Non-WR) and 26.3% (WR). Although the Japanese soils had high SOC contents in >10 cm depths, they were not WR (for Nikko >5 cm depth-Not WR). Therefore, further studies are needed to assess SWR as affected by SOC.