1. Key Laboratory for Environmental Pollution Prediction and Control, Gansu Province, Key Laboratory of Western China’s Environmental Systems Stems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, P. R. China
2. Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, P. R. China
3. School of Public Health, Chengdu University of Traditional Chinese Medicine, Chengdu 610000, P. R. China