A methodology for examining the long-range transport and the source-receptor relationships for acidic pollutants

A receptor-oriented methodology was applied to study the source-receptor relationships for sulfur dioxide, particulate sulfate and non-sea salt sulfate collected at a background site in France. In this methodology, chemical data and air parcel backward trajectories were combined to produce concentration field maps of likely contributing sources. The sources were essentially identified outside France in known European regions of high emissions of SO2. The quantitative relationships between the computed concentration maps and the European emissions of SO2 are examined performing a correlation analysis. Satisfying correlations were found between the sulfur species and the SO2 emitted above 100 meters, while weaker correlations were found between these same species and the SO2 emissions below 100 meters. The results of this study mean that the occurrence of high sulfur concentrations at once in gas, particles and in precipitation at Morvan are mainly caused by the long range transport of anthropogenic SO2 and SO2's secondary species. The SO2 emitted above 100 meters seems to be the major cause of episodes of high SO2 concentrations, particulate SO42- concentrations and non-sea salt SO42- concentrations in precipitation at the receptor site.