A dual site study of PM2.5 and PM10 aerosol chemistry in the larger region of Vienna, Austria

The measurements of PM2.5 and PM10 at two sites—an urban site in Vienna (AUPHEP-1) and a rural site considered local background (AUPHEP-2)—indicated only low aerosol generation activity in the city on an annual basis. Defining the term “urban impact” as the difference between observations at the urban and the local background site we find an annually averaged urban impact for PM2.5 of 3.4 μg m−3 and for PMC of 3.3 μg m−3 (the coarse fraction PMC=PM10−PM2.5). The relative increase of the particulate matter (PM) concentration at the urban site compared to the background site (AUPHEP-2) is annually averaged only 19% for PM2.5, but 60% for PMC. The chemical main constituents of the PM2.5 urban impact are black carbon (BC), organic carbon (OC), and sulfate; the main constituents of the PMC urban impact are OC and indicators for mineralic aerosol (Fe, Ca, Mg, Na, K). The BC/TC ratio of the PM2.5 urban impact is typical as for combustion sources, e.g. automotive traffic, oil or coal combustion. Urban coarse OC is considered to originate from non-pyrogenic sources. From the trace metals investigated (As, Cd, Co, Cu, Cr, Mn, Ni, Pb, V, Zn) only Cd, Ni, Pb, and Zn exhibited a slight cold season enrichment in the urban airshed. From the weak signal of a seasonality of oil or coal combustion indicators we conclude that local domestic heating sources are using “clean fuels”.