1. Tianjin Center China Geological Survey Tianjin 300170 P.R. China
2. School of Water Resources and Environment China University of Geosciences (Beijing) Beijing 100083 P.R. China
3. Center for Hydrogeology and Environmental Geology China Geological Survey Baoding 071051 Hebei P.R. China
4. State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences (Beijing) Beijing 100083 P.R. China