1. Department of Chemistry, and Department of Environment and Geography, University of Manitoba, Winnipeg, MB R3T 2N2, Canada, Department of Fisheries and Oceans, Freshwater Institute, Winnipeg, MB R3T 2N6, Canada, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, P.R. China, and State Key Laboratory of the Cryospheric Science, Chinese Academy of Sciences, Lanzhou 730000, P.R. China