1. School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
2. Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge Massachusetts 02139, United States
3. Center for Rural Environment Protection, Chinese Academy for Environmental Planning, Beijing 100012, China
4. Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
5. School of Science, Tibet University, Lhasa 850012, China
6. School of Environment and Natural Resources, Renmin University of China, Beijing 100872, China
7. College of Urban and Environmental Sciences, Peking University, Beijing 100871, China