Utilization of a landscape level airborne mercury survey network to evaluate residual contamination from agricultural use in the Shenandoah Valley, VA.
Temple, Susan*,1, Allak, Amir2, Kelley, Allison 3, Lumbi, Zamda1, Ditzler, Kristin1, Wilson, James4, Cocking, Dean1, 1 James Madison University, Harrisonburg, VA2 University of Virginia Medical School, Charlottesville, VA3 Augusta Medical Center, Fishersville, VA4 Old Dominion University, Norfolk, VA
ABSTRACT- Apple orchard operations are extensive in Rockingham Co. VA, and this land use has been important since the civil war. Mercury based fungicides were applied to control a variety of diseases prior to their ban for agricultural applications in the mid-1900's. Residues of this heavy metal do not degrade and remain in the soil. It is hypothesized that this source of airborne Hg contamination non-randomly supplements regional atmospheric deposition at the landscape level. This is being examined through a survey of 84 locations in the City of Harrisonburg and environs of Rockingham Co. Deposition is sampled using inexpensive passive collectors constructed from plastic Petri plates. They were poured with Tangletrap™, a sticky substance used to trap insects in order to facilitate particulate capture. Then replicate plates were stapled to telephone poles dispersed according to a random grid over approximately 200 km2 of predominantly rural landscape. A preliminary study indicated that Harrisonburg experienced Hg deposition (0.256 mg/m2/mo) which was significantly greater (p<0.01) than unexposed plates (0.028 mg/m2/mo). The Harrisonburg concentrations tended to be greater than those in a city with little Hg pollution, Staunton, VA, (0.162 mg/m2/mo) (0.20>p>0.10) and were more variable. The data were geospatially referenced using GIS for comparison with the historic orchard distribution. The non-random dispersion of airborne Hg deposition, while not always related to readily identifiable potential sources, does facilitate the formulation of hypotheses and supports the utility of this relatively inexpensive study method for airborne toxicants which are illusive landscape habitat factors to evaluate.
Key words: landscape ecology, mercury toxicological cycling, GIS mapping
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