Chemical components and distributions in glaciers of the Third Pole

Abstract The Tibetan Plateau (TP) and its surroundings contain a large volume of glaciers. Glaciochemistry in this region can provide valuable information on current and past climatic change and environmental conditions. In this chapter, the spatial–temporal characteristics of glacier chemistry on the TP are summarized, including major ions, trace elements, persistent organic pollutants, black carbon (BC) and organic carbon, and mineral dust. Current spatial distributions of chemical composition generally indicate a higher concentration in the northern TP in comparison with the central and southern plateau. Seasonality shows different patterns in the southern and northern plateau because of the alternate dominant influence of the South Asian monsoon and westerlies. Due to higher chemical loading in the nonmonsoon season and heavy precipitation in summer, chemicals show lower values in summer and higher values in winter, especially on the southern plateau; while in the Pamir region, higher values occur in the spring to summer. Historical variations highlight the impact of anthropogenic activities, especially since the Industrial Revolution. Potential sources of chemicals in glaciers are documented by backward trajectory and Nd–Sr/carbon isotope distributions, which further emphasize the impacts of pollutants emitted from South and Central Asia. The impacts of BC and mineral dust on glacier melt are also discussed. These results will help us to understand the status of glaciochemistry in the world’s highest plateau, and the possible impact of glacier melt on water quality in downstream.