Concentrations and chemical forms of heavy metals in the bulk atmospheric deposition of Beijing, China.

This study aimed to investigate concentrations and mobility of selected metals (As, Cd, Cr, Co, Cu, Mn, Ni, Pb and Zn) contained in the bulk atmospheric deposition of Beijing, China, between March 2007 and February 2008, and to evaluate the metal deposition fluxes. Beijing endured heavy atmospheric deposited metal pollution with a deposition flux of 149.28 kg km-2 year-1 from nine metals studied, and a significant increasing trend was noted from metals studied during the past 23 years. High enrichment factors (EFs) of As, Zn, Pb, Cd, and Cu manifested their major anthropogenic sources. Among which, Cd and Pb require a consistent monitoring and to be strictly controlled regarding their high mobility and ecotoxicity. Furthermore, a declined metal concentration was observed in the bulk atmospheric deposition during spring, and long-transported crustal particles sourced from East Asian dust emission belt can reasonably account for this phenomenon.