Records of sulfate and nitrate in an ice core from Mount Muztagata, central Asia

Annually resolved ice core records of major soluble ions (Na+, NH4+, K+, Mg2+, Ca2+, Cl-, SO42-, and NO3-) covering the period 1907-2002 A. D. from Mount Muztagata in central Asia are presented in this paper. Time series of major ion concentrations generally exhibit very similar temporal trends except NO3- and NH4+. Statistical analyses show that the chemical composition in the Muztagata ice core is predominantly controlled by terrestrial dust inputs originating from the extensive arid and semiarid regions of central Asia. However, by comparison with the typical dust-derived ion Ca2+, the SO42- and NO3 concentrations increase more rapidly after the mid-1970s and late 1970s, respectively, possibly indicating the strong anthropogenic contributions from then on. The good agreements between SO42- and NO3 concentration records and their precursor gas emissions from central and southwest Asia suggest the potential source regions contributing to the Muztagata ice core records.