CURRENT METHODS OF ESTIMATING ATMOSPHERIC MERCURY FLUXES IN REMOTE AREAS

Evaluation of the impact of anthropogenic mercury (Hg) emissions to the atmosphere requires an understanding of natural background levels and cycling processes. Baseline geochemical surveys indicate that Hg is a significant and highly variable natural constituent of bedrock, surficial sediments, and vegetation. To evaluate the geological contribution of Hg to aquatic systems and to the atmosphere, methods are needed to translate existing spatial geochemical data into annual flux estimates. At the global scale, estimates of the geological component of the atmospheric Hg cycle vary widely, depending on which sources are considered, the magnitude of the Hg emission factors used, and the geographic area to which these emission factors are applied. Plate tectonic theory offers a useful framework for interpreting Hg distribution patterns on the earth's surface and a means of quantifying the magnitude of geological loading to the oceans, the latter being a critical component of the global Hg cycle.