1. Dep. of Environ. Engineering; Aalborg Univ.; Sohngaardsholmsvej 57 DK-9000 Aalborg Denmark
2. Dep. of Regional Crops Science, Natl. Agric. Res. Center for Western Region; Senyu 1-3-1 Zentsuji Kagawa 765-8508 Japan
3. Graduate School of Science and Engineering, Saitama University; 255 Shimo-Okub Saitama 338-8570 Japan
4. Soils and Biogeochemistry, Dep. of Land, Air, and Water Resources; Univ. of California; Davis CA 95616