1 College of Geoscience and Surveying Engineering, China University of Mining and Technology, Beijing 100083, China.
2 State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China. Electronic address: chshwang@cugb.edu.cn.
3 German Research Centre for Geosciences, Potsdam 14473, Germany.
4 State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China.