Model Assessment of the Annual Atmospheric Deposition of Trace Metals to Lake Superior

摘要

Mass balance studies indicate atmospheric deposition of toxic pollutants to the Great Lakes accounts for a significant portion of the total loading. Identifying the types and locations of both natural and anthropogenic sources of these loadings is imperative before effective and efficient emission control strategies are developed. A regional atmospheric dispersion model, in tandem with an anthropogenic toxics emission inventory, was applied to calculate the atmospheric deposition of five trace metals to Lake Superior for the entire year of 1989. Although there are significant uncertainties in the emission estimates, the model results illustrate three significant points. First, less than 1% of the trace metal mass emitted from sources within the modeling domain are deposited to Lake Superior. Second, long-range transport of trace metals to Lake Superior is significant, especially for cadmium, chromium, and nickel. Finally, both the significance of long-range transport and total annual atmospheric deposition to the Lake increase for the smaller 0.5 micrometer particle size.