Controls on Mercury and Methylmercury Deposition for Two Watersheds in Acadia National Park, Maine |
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| Authors: | K B Johnson T A Haines J S Kahl S A Norton Aria Amirbahman K D Sheehan |
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| Institution: | (1) Senator George J. Mitchell Center for Environmental and Watershed Research, 5710 Norman Smith Hall, University of Maine, Orono, ME 04469, USA;(2) U.S. Geological Survey, Orono Field Station, Leetown Science Center, Orono, ME, USA;(3) Department of Geological Sciences, University of Maine, Orono, ME, USA;(4) Department of Civil Engineering, University of Maine, Orono, ME, USA;(5) Department of Biological Sciences, University of Maine, Orono, ME, USA;(6) Center for the Environment, Plymouth State University, Plymouth, NH, USA |
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| Abstract: | Throughfall and bulk precipitation samples were collected for two watersheds at Acadia National Park, Maine, from 3 May to
16 November 2000, to determine which landscape factors affected mercury (Hg) deposition. One of these watersheds, Cadillac
Brook, burned in 1947, providing a natural experimental design to study the effects of forest type on deposition to forested
watersheds. Sites that face southwest received the highest Hg deposition, which may be due to the interception of cross-continental
movement of contaminated air masses. Sites covered with softwood vegetation also received higher Hg deposition than other
vegetation types because of the higher scavenging efficiency of the canopy structure. Methyl mercury (MeHg) deposition was
not affected by these factors. Hg deposition, as bulk precipitation and throughfall was lower in Cadillac Brook watershed
(burned) than in Hadlock Brook watershed (unburned) because of vegetation type and watershed aspect. Hg and MeHg inputs were
weighted by season and vegetation type because these two factors had the most influence on deposition. Hg volatilization was
not determined. The total Hg deposition via throughfall and bulk precipitation was 9.4 μg/m2/year in Cadillac Brook watershed and 10.2 μg/m2/year in Hadlock Brook watershed. The total MeHg deposition via throughfall and bulk precipitation was 0.05 μg/m2/year in Cadillac Brook watershed and 0.10 μg/m2/year in Hadlock Brook watershed. |
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| Keywords: | mercury methylmercury throughfall atmospheric deposition Maine USA Acadia National Park |
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