Environment information encoded in major ion concentrations in the Noijin Kangsang ice core of the southern Qinghai-xizang Plateau

A 55 m long ice core was drilled from the Noijin Kangsang glacier on the southern Qinghai-xizang Plateau in 2007． The ice core was drilled close to bedrock and annually dated covering the period of 1864-2006． The concentrations of major soluble ions (Ca²⁺、\mathrmNH_4^+ 、Na⁺、Mg²⁺、K⁺、\mathrmNO_3^- 、\mathrmSO_4^2- 、Cl⁻) in the ice core were measured, ion concentration variations and ion sources were analyzed by empirical orthogonal function (EOF) and atmospheric circulation field analysis． The variations of soluble ion concentrations in the ice core are found to be highly consistent and correlated． The land mineral dust in the arid and semi-arid regions of northern South Asia is the main source of soluble ions, variations in concentration are controlled by westerly circulation． Higher ice core ion mass concentrations during the periods 1864-1922 and 1950-1970 correspond to colder periods of Northern Hemisphere climate and stronger westerly circulation. During the time period covered by the ice cores, there is an overall decreasing trend in ice core ion mass concentrations, indicating an overall weakening of the westerly circulation.