1. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, P. R. China
2. State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430078, P. R. China
3. State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, P. R. China