MERCURY WET DEPOSITION PATTERNS AT THOMPSON FARM, DURHAM, NH - JULY 2006 TO SEPTEMBER 2009

Mercury (Hg) is a global contaminant of concern due to its known toxicity and ubiquitous presence in the atmosphere. The primary source of Hg to terrestrial and aquatic ecosystems is atmospheric deposition. In an effort to understand the atmospheric behavior and deposition of Hg, event-based wet deposition samples have been collected from July 2006 to September 2009 at Thompson Farm (TF), a near-coastal rural site in Durham, NH. These samples have been analyzed for total aqueous mercury. Seasonal trends in Hg wet deposition exist at TF. Lower deposition occurs in the winter with an average total deposition of 1.56 mg m^-2 compared to the summer average total deposition of 4.71 mg m^-2. Similar trends have been observed at Mercury Deposition Network (MDN) sites located throughout the Northeastern United States. The deposition values at TF are typically elevated compared to those reported at MDN sites located in the adjacent state of Maine, possibly reflecting the proximity of TF to urban sources. In-depth analysis will be conducted using meteorological data and concurrent measurements of continuous gaseous elemental and reactive mercury to understand the mechanisms contributing to the observed variations in Hg wet deposition.