1. Ph.D. Candidate, Laboratory of Earth Surface Processes, College of Urban and Environmental Sciences, Peking Univ., Beijing 100871, China.
2. Lecturer, Institute of Reproductive and Child Health, Ministry of Health Key Laboratory of Reproductive Health, School of Public Health, Peking Univ., Beijing 100191, China.
3. Associate Professor, Laboratory of Earth Surface Processes, College of Urban and Environmental Sciences, Peking Univ., Beijing 100871, China.
4. Professor, Dept. of Mechanical and Nuclear Engineering, School of Engineering, Virginia Commonwealth Univ., Richmond, VA 23284.
5. Professor, School of Environment, Jinan Univ., Guangzhou 510632, China.
6. Professor, Laboratory of Earth Surface Processes, College of Urban and Environmental Sciences, Peking Univ., Beijing 100871, China (corresponding author).