1. Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, 810008 Xining, P. R. China
2. Qinghai Engineering and Technology Research Center of Comprehensive Utilization of Salt Lake Resources, 810008 Xining, P. R. China
3. University of Chinese Academy of Sciences, 100049 Beijing, P. R. China