| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 2004: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2003: ¥100,000 (Direct Cost: ¥100,000)
Fiscal Year 2002: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
Surfactants are used in detergents, shampoos, chemical fertilizers, agricultural chemicals, and the like, and a large amount of the surfactants has been discharged to the environment. Surfactants are also used for contaminated soil washing and amelioration of soil-water repellency. However, their influence on the soil environment is not fully understood. In this study, we investigated the influence of an anionic surfactant on water infiltration. Sodium dodecyl sulfate (SDS) solutions of different concentrations were infiltrated by capillary rise into dry material columns. We proposed a capillary rise equation and used it to explain the influence of SDS. In glass beads and sand, which are hydrophilic inorganic materials, the infiltration rate decreased as the SDS concentration increased due to the decrease of the surface tension of the solution. In polyethylene particles and peat moss, which are hydrophobic organic materials, the infiltration rate increased as the SDS concentration increased because of the decrease in the contact angle and the surface tension. In the case of leaf mold, the infiltration rate decreased as the SDS concentration increased due to the decrease of the saturated hydraulic conductivity caused by swelling. Interfacial phenomena clearly affected the infiltration rate into the soils.
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