1. Department of Environmental Engineering, Norwegian Geotechnical Institute (NGI), P.O. Box 3930, Ullevål Stadion, N-0806, Oslo, Norway
2. Department of Crop and Soil Sciences, Cornell University, Ithaca, New York 14853, United States
3. Department of Geological Sciences, University of Florida, 241 Williamson Hall, P.O. Box 112120, Gainesville, Florida 32611, United States
4. Department of Applied Environmental Sciences, Stockholm University, 10691 Stockholm, Sweden
5. Institute for Plant and Environmental Sciences, University of Life Sciences, 5003 Ås, Norway