1. Environmental Engineering Lab., Dep. of Civil Engineering; Aalborg Univ.; Sohngaardsholmsvej 57 DK-9000 Aalborg Denmark
2. Dep. of Crop Physiology and Soil Science; Danish Institute of Agricultural Sciences; Research Centre Foulum; P.O. Box 50 DK-8830 Tjele Denmark
3. Dep. of Civil and Environmental Engineering, Faculty of Engineering; Hiroshima Univ.; 1-4-1 Kagamiyama Higashi-Hiroshima 739 Japan
4. Soils and Biogeochemistry, Dep. of Land, Air and Water Resources; Univ. of California; Davis CA 95616 USA