Atmospheric dust aerosols over the Eastern Pamirs: major element concentrations and composition

Abstract

This study measured the major element con- centrations and compositions of atmospheric dust aerosol samples collected weekly for nearly 2 years at Mt. Muz- tagata, a remote and high-elevation site (3817 0 N, 7501 0 E, 4,430 m) in the Eastern Pamirs. Inductively coupled plasma mass spectroscopy (ICP-MS) results show that on the weekly timescale, air at Muztagata contained average element Al concentrations of 842 ng m -3 between June 2004 and December 2005, and 509 ng m -3 between June 2005 and April 2006. The dust load over the Eastern Pamirs appears to be far lower (by more than an order of magnitude) than those in northern China. The Muztagata dust aerosols show Ca/Al ratios (*0.7) and Fe/Al ratios (*0.7) that differ from that in northern China. The general homogeneity exists in the major element compositions, expect Ca/Al ratios which show minor but clear seasonal variations. Element ratios vary with aerosol concentration. Results indicate that concentrations and compositions of Asian dust change significantly between different emission regions, and confirm that major element ratios can be used to efficiently characterize the dust aerosols composition at different sites in northern China.