Concentrations and seasonal variation of ambient PM(2.5) and associated metals at a typical residential area in Beijing, China.

In this study, continuous monitoring of PM2.5 was carried out for 1 year period at one of the largest residential areas in Beijing. Annual mean of PM2.5 during sampling period was 100.4 µg/m(3). The seasonal variation trend of PM2.5 was winter > spring > autumn and summer. The total mass concentrations of metals in PM2.5 ranged from 0.4 to 13.2 μg/m(3). There were significant (p < 0.05) seasonal variations for concentrations of Ca, Al, Mn, As, Rb, Cr, Ni, Cd and Co, seasonal variations in PM-associated metals were not necessarily the same as the seasonal variation in PM2.5, related to differing seasonal trends in source types. The impact of meteorological factors (e.g., wind speed) on metals levels of PM2.5 was found to be significant by regression models. The EFs value of Ag, Ca, Cd, Pb, Zn, As, Cu, and Cr were higher than ten, suggesting that those elements were primarily contributed by anthropogenic sources. Seasonal characteristic of EFs were found for As, Cr, Ca and Ag, which indicating the seasonal pollution sources types for those metals. Overall, these findings indicated that the pollution control of ambient PM2.5 should not be negligible in residential area in Beijing and the local government should pertinent and accurate prevent and control of air pollution as well as protect human health.