The chemistry and transport of mercury in a small wetland in the Adirondack region of New York, USA

The biogeochemistry of Hg was evaluated in a small wetland in the Adirondack region of New York. Concentrations of total Hg (Hg-T) in streamwater draining the wetland showed little temporal variation, The annual areal watershed flux of Hg-T (2.2 mu g/m(2)-yr) was considerably smaller than regional inputs of atmospheric deposition of Hg-T, indicating that the terrestrial environment is a net sink for atmospheric deposition of Hg-T. Drainage inputs of Hg-T were conservatively transported through the beaver impoundment. The annual flux of total methylmercury (CH3HgT+) was greater than literature values of atmospheric deposition suggesting that the watershed is a net source of CH3HgT+. Stream concentrations of CH3HgT+ increased during low-flow summer conditions in a riparian wetland, and particularly at the outlet of the beaver impoundment. Net production of CH3HgT+ occurred in the beaver impoundment (0.45 mu g/m(2)-yr). Rates of net methylation for the beaver impoundment were comparable to values reported in the literature for wetlands.