Source-receptor relationships for heavy metals in the European atmosphere

Atmospheric concentrations of heavy metals (HMs), in particular As, Cd, Cu, Pb and Zn, were studied in an effort to contribute to the understanding of European source-receptor relationships. A comparison was made between the ambient concentrations measured at 11 background aerosol monitoring stations (in Denmark, the Czech Republic, Finland. Norway and Sweden) and the corresponding HM concentrations estimated by the Heavy Metals Eulerian Transport (HMET) meteorological dispersion model. The collected samples which were analysed with Particle Induced X-ray Emission analysis (PIXE) except the Finnish samples which were analysed with Inductively Coupled Plasma - Mass Spectrometry. (ICP-MS). The available data covers the period 1985-1994. The comparison showed that the European emissions of As, Cd and Pb seem to be fairly well estimated. On the other hand, the European Zn emissions are underestimated by a factor of 3 or more, while the Cu emissions appear to be slightly overestimated. The HMET dispersion model also made it possible to select occasions for which the sampling sites had a substantial contribution of HM from the highly polluted ''Black Triangle" region (on the borders between the Czech Republic, Poland and Germany). The time evolution of the sources of HMs within this source region could be studied by applying various statistical receptor models on the extensive data set from two Danish stations, Keldsnor and Tange, covering the period 1985-1994. Four source types were clearly discerned throughout the 10 year time period. These sources were: soil dust: sea spray, general combustion and oil combustion. The strong time-dependence observed for the contribution from the Black Triangle region emphasizes the importance of keeping the emission inventories continuously updated if HMs deposition calculations and HMs emissions reduction protocols are to be based on dispersion modelling approaches. (C) 1999 Elsevier Science B.V. All rights reserved.