Chemical composition and sources of PM_2.5 and TSP collected at Qinghai Lake

PM_2.5 and total suspended particulates (TSP) samples were collected from June to September 2010 at Qinghai Lake, northeastern Tibetan Plateau. The concentrations of major water soluble ions, 12 elements, elemental carbons (EC) and organic carbons (OC) were quantified. Mass concentrations of PM_2.5 and TSP were 21.27 ± 10.70μg/cu m and 41.47 ± 20.25 μg/ cu m, respectively, and the mean ratio of PM_2.5/TSP was 0.51. SO₄^2- and Ca²⁺ were the greatest anion and cation both in PM_2.5 and TSP samples, respectively. EC has various sources including diesel engine emissions, fossil fuel combustion at low burning efficiency and biomass burning. Crustal elements such as Ca, Fe and K were the main element in aerosol samples, and their enrichment factors (EF) were lower than 10. EFs for Pb, As and Zn were greater than 10, indicating they were influenced by anthropogenic sources. EC concentrations were 0.33 ± 0.17 μg/cu m and 0.47 ± 0.28 μg/cu m in PM_2.5 and TSP, respectively, while the concentrations of OC were 1.49 ± 0.63 μg/cu m and 2.30 ± 0.95 μg/cu m in PM_2.5 and TSP. Most of the EC was related to biomass burning emissions and traffic-related sources. Due pollution from local sources, the ratios of OC/EC were 4.77 ± 1.32 and 5.23 ± 1.39 in PM_2.5 and TSP, respectively, which were lower than other remote sites. Salt particles produced by the salty lake reacted with acid gases, and then caused the most nitrates and a small fraction of sulfate distributed in the coarse mode and Cl deficit in aerosol samples. Concentrations of SO₄^2- and OC were influenced by long distance transport from eastern China, as well as As, Pb and Zn concentrations. This is an abstract of a paper presented at the 106th AWMA Annual Conference and Exhibition (Chicago, IL 6/25-28/2013).