MEASURED FLUXES OF SULFUR, CHLORINE AND SOME ANTHROPOGENIC METALS TO THE SWEDISH WEST-COAST

Deposition measurements were performed during one month in autumn 1992 in a rural place on the west coast of Sweden, Airborne particle concentrations and deposition fluxes were measured simultaneously. Aerosol sampling was made with a dichotomous virtual impactor which size segregated the particles into fine (< 2.5 mu m) and coarse particles (2.5-10 mu m). The flux determination consisted in measuring the total (bulk) deposition, wet deposition and dry deposition to three surrogate surfaces. A modified Andersen deposition sampler was used to discriminate between the dry and the wet periods. The analytical techniques for element analysis were EDXRF, ICP/MS and ion chromatography. By correlation analysis of the airborne elemental concentrations in fine and coarse particles it was possible to identify sources of the encountered aerosol. The K/Cl Ca/Cl and Br/Cl ratios in coarse particles were very close to those in sea water, suggesting a predominantly marine source of coarse particle Cl, K, Ca, and Br. The highest correlations were obtained for coarse particle Br vs Cl (0.99) and for coarse particle K vs Ca (0.98). The Br/Pb ratio in fine particles, approaching the ''ethyl ratio'' in fresh car exhaust, indicated that traffic was the dominant source of the fine particle Br and Pb. The positive correlations between most of the metals in fine particles indicated long distance transport from industrial source regions in Europe. The measured dry and wet deposition fluxes are reported for S, Cl, V, Mn, Fe, Ni, Cu, Zn and Pb, and estimates of annual total deposition at the measurement site are given and compared with reference data. The general feature is that fluxes are smaller in the northeast part of the North Sea compared to the southern part. Average dry deposition velocities obtained in the present study are compared with reference data and also with the elemental coarse/fine particle ratios. These ratios give a rough estimate of what deposition rate to expect. The fine particle elements having coarse/fine ratios less than one (V, Ni, Zn, Pb and S) have lower dry deposition velocities than coarse particle elements (Mn, Fe, Cu, Cl).