1. Postdoctoral Researcher, Dept. of Geosciences, Univ. of Oslo, Sem Sælands vei 1, 0316 Oslo, Norway.
2. Professor, Dept. of Civil and Environmental Engineering, Michigan Technological Univ., 1400 Townsend Dr., Houghton, MI 49931.
3. Professor, Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China (corresponding author).