1. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, P. R. China
2. University of Chinese Academy of Sciences, Beijing 100049, P. R. China
3. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, P. R. China
4. School of Water, Energy and Environment, Cranfield University, Cranfield MK430AL, United Kingdom
5. Center for Excellence in Quaternary Science and Global Change, Chinese Academy of Sciences, Xian 710061, P. R. China