Size-distributed metallic elements in submicronic and ultrafine atmospheric particles from urban and industrial areas in northern France

摘要

To determine the size distribution of potentially toxic trace metals (TM) in atmospheric particulate matter (PM), sampling experiments were performed in the urban-industrial area of Dunkirk (North of France) during winter 2012. Total mass concentrations are in accordance with typical values obtained at European urban background sites but lower than the concentrations reported for some Asian industrial countries. Considering the local wind directions, mass concentrations are higher downwind of urban influences than downwind of industrial emissions. The mean PM_(10) mass concentration (25-30 μg/m~3) is less than the European Union and US EPA limit values (40-50 μg/m~3) but greater than the WHO guidelines (20 μg/m~3). The calculated TM crustal enrichment factors (EF_(Crust)) suggest the anthropogenic origins of most of the studied TM (Sb, Cd, As, Mo, Pb, Zn. Cu, Ni, Cr, Mn and V). The highest TM concentrations were obtained for Zn and Mn (＞50 ng/m～3) under industrial influence, but the finest particle (＜ 0.29 μm) concentrations were higher for the urban sector than for the industrial sector. This enrichment may be attributed to local urban traffic. In contrast, trace metals are more abundant in the coarser fraction (＞ 0.29 μm) downwind of industrial emissions. Moreover, mechanical operations associated with industrial processes (excavating, crushing, and sintering), as well as the resuspension of industrial soils, likely represent some significant TM source-terms in the supermicronic fraction. The EF_(Crust) comparison between the two prevailing sectors demonstrates the importance of steelworks and smelting emissions in the abundance of some TM (As, Cd, Fe, Mn, Mo, Pb, Rb and Zn). In contrast, the Cr and Co concentrations seem to be more related to coal combustion emissions, Cu and Sb to automotive traffic, and V, La and Ni to petrochemical activities.