full text is available online.
|Author:||Sarah J. Nelson|
|Title:||Determining Atmospheric Deposition Inputs to Two Small Watersheds at Acadia National Park|
|Department:||Ecology and Environmental Science|
|Committee Chair:||J. Steve Kahl, Director, Senator George J. Mitchell Center for Environmental and Watershed Research|
|Committee Members:||Christopher S. Cronan, Professor of Botany and Ecology; Ivan J. Fernandez, Professor of Soil Science; Alan S. White, Associate Professor of Forest Ecosystem Science|
|Subjects:||Watershed ecology -- Maine -- Acadia National Park|
|Date of Defense:||2002|
Two small upland watersheds have been gauged and monitored at Acadia National Park since 1998. Cadillac Brook watershed burned in a wildfire in 1947. Hadlock Brook watershed has been undisturbed for several centuries, and serves as the reference site. Precipitation and throughfall volume and chemistry data have been collected using wetonly and continuously open collectors. Hydrologic and chemical inputs to the sites have been determined for each site. Differences in watershed and vegetation characteristics control the input of water and major ions to these watersheds. Vegetation type was the dominant control on enhancement of precipitation across the heterogeneous watersheds. Relative annual enhancement of throughfall over wet-only deposition for coniferous stands at Hadlock was 2.0 for NH4 and NO3, 2.7 for SO4, 7.1-7.3 for C1 and Na, 6.8 for Ca, 92 for Mg, and 58 for K. Enhancement was similar for mixed stands, intermediate for deciduous stands, and lowest (except C1 and Na) at scrub and open sites. At Cadillac, enhancement was slightly lower for each ion, but the same pattern, coniferous = mixed > deciduous > scrublopen, was observed. Seasonal differences were important, with highest deposition in fall and summer; however, wet deposition inputs of C1 and Na were highest in winter. Elemental stream flux was calculated using discharge data from the U. S. Geological Survey, combined with periodic water chemistry data. The chemical mass balance in the watersheds was determined from streah outputs minus wet inputs, where negative values indicate retention within the watershed. At Cadillac and Hadlock, H, Mg, K, N a , and NO3 are retained; Ca and SO4 are lost. Retention of DM (NO3 plus NH4) was 96% at Cadillac and 72% at Hadlock, indicating that differences related to vegetation andlor soils control the relative patterns of retention and release.
Nelson, Sarah J., University of Maine, EES2002-011