1. Key Laboratory of Aerosol Chemistry & Physics, State Key Laboratory of Loess and Quaternary Geology (SKLLQG), Institute of Earth Environment, Chinese Academy of Sciences (CAS), Xi’an 710061, P. R. China
2. CAS Center for Excellence in Quaternary Science and Global Change, Xi’an 710061, P. R. China
3. University of Chinese Academy of Sciences, Beijing 100049, China
4. Department of Science and Environmental Studies, The Education University of Hong Kong, Hong Kong, P. R. China
5. Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, P. R. China