1. Dep. of Agroecology, Faculty of Science and Technology; Aarhus Univ.; Blichers Allé 20, P.O. Box 50 DK-8830 Tjele Denmark
2. Dep. of Soil, Water and Environ. Sci.; The Univ. of Arizona; Tucson AZ 85721
3. Dep. of Biotechnology, Chemistry and, Environmental Engineering; Aalborg Univ.; Sohngaardsholmsvej 57 DK-9000 Aalborg Denmark
4. Institute of Civil Engineering, Univ. of the Philippines; Diliman Philippines
5. Graduate School of Science and Engineering and Institute for, Environmental Sci. and Technology, Saitama Univ.; 255 Shimo-Okubo Sakura-ku Saitama 338-8570 Japan