1. State Key Laboratory of Loess and Quaternary Geology (SKLLQG)Institute of Earth EnvironmentChinese Academy of Sciences Xi'an 710061 China
2. Key Laboratory of Aerosol Chemistry & PhysicsInstitute of Earth EnvironmentChinese Academy of Sciences Xi'an 710061 China
3. Center of Excellence in Quaternary Science and Global ChangeChinese Academy of Sciences 710061 Xi'an Shaanxi China
4. Department of Science and Environmental StudiesThe Education University of Hong Kong Tai Po, New Territories Hong Kong China