1. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
2. Environmental Geosciences, University of Basel, 4056 Basel, Switzerland
3. Institute of Agricultural Sciences, ETH Zurich, 8092 Zurich, Switzerland
4. Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland