1. CAS-Key Laboratory of Crust-Mantle Materials and the Environments; School of Earth and Space Sciences; University of Science and Technology of China; Hefei 230026 China
2. State Key Laboratory of Loess and Quaternary Geology; Institute of Earth Environment; The Chinese Academy of Sciences; Xi'an Shaanxi 710075 China
3. Microelement Research Center; College of Resources and Environment; Huazhong Agricultural University; Wuhan 430070 China