CHESAPEAKE BAY ATMOSPHERIC DEPOSITION STUDY, YEAR-1 - SOURCES AND DRY DEPOSITION OF SELECTED ELEMENTS IN AEROSOL-PARTICLES

Week-long aerosol particulate samples collected over a 57-week period at two shoreline sites along the northern Chesapeake Bay were analysed for up to 44 elements, including 14 elements of interest to Bay water quality (i.e. Al, As, Cr, Fe, Mn, S, Se, V and Zn, by nuclear; and Cd, Cu, Ni and Pb by atomic spectroscopy techniques) to examine their temporal and spatial variations in Bay air, sources, and estimate dry deposition fluxes to the Bay surface. The concentrations of non-crustal elements V, Se, Cr and Zn were elevated in winter months, whereas elements with substantial crustal residence, Al, Fe and Mn, were elevated during periods in spring and summer. Despite substantial differences in weekly concentrations, annual average concentrations determined for the two sites were quite similar, differing by less-than-or-equal-to 23% for all elements except Al, 35%. Chemical mass balance calculations made with 11 generic sources suggest that incinerators were important sources of Cr, Cd, Sb and Zn in Bay air; oil combustion, V; regional sulfate, S; local coal combustion, Se; steel, As; and soil, Al, Fe and Mn, with small amounts from wood combustion, regional sulfate, steel and coal combustion. Lead and Cd concentrations were well correlated and peaked in fall, suggesting another important source for these elements. Estimated dry deposition fluxes were comparable to wet fluxes for all elements.