POSSIBLE SOURCES AND PREFERRED PATHWAYS FOR BIOGENIC AND NON-SEA-SALTSULFUR FOR THE HIGH ARCTIC

Sulfate is a major constituent observed in Arctic haze. Sulfur sources include anthropogenic, biogenic, and other natural sources. Previous studies have examined the concentrations and temporal variability of t he concentrations of methanesulfonic acid (MSA) and sulfate(SO4=) at A lert, Northwest Territories, Canada. A receptor modeling method called the potential source contribution function (PSCF) combines the concen tration data for these species measured in 7-day samples continuously collected between 1980 and 1991 with meteorological information in the form of air parcel back trajectories into conditional probability map s indicating the possible source areas and/or the preferred pathways t hat give rise to the observed high-concentration samples. After examin ation of the time series for MSA and SO4=, the data were segregated in to time periods representing the spring, summer, and winter months and the PSCF analyses performed based on criterion values of the annual a verage species concentration. The potential source contribution method has been found to be effective in identifying possible source locatio ns and the preferred pathways of MSA and SO4= in samples collected at Alert. Two concentration peaks are typically observed in the time seri es for MSA. The time series for SO4= is quite different from the serie s for MSA. The SO4= series only has peaks in the winter caused primari ly by anthropogenic emissions. It was found that different regions of the North Atlantic Ocean contribute to the observed MSA concentrations during these different periods in agreement with prior hypotheses. So urces areas for sulfate during the summer and MSA during the winter ca n only be observed by changing the criterion value to the average duri ng the period.