Estimation of annual trace element deposition to the Chesapeake watershed
- Maryland Dept. of Natural Resources, Annapolis, MD (United States)
- Pennsylvania State Univ., University Park, PA (United States)
- Univ. of Maryland, College Park, MD (United States)
Trace elements are emitted to the atmosphere from a variety of natural and anthropogenic sources, including fossil fuel combustion, incineration, and agricultural and construction activities. In recent years precipitation and aerosol concentrations have been made at several locations throughout the Chesapeake Bay watershed, which have been used to estimate direct deposition to the Bay surface. These measurements indicate that for many elements (e.g., Al, Cd, Cr, Mn, Pb and Zn) atmospheric flux is comparable to their dissolved riverine input. Furthermore, an unknown fraction of the fluvial input is derived indirectly from atmospheric deposition to the watershed and eventual transmission through the watersheds. Although the degree of transmission is presumed to be relatively small, by virtue of the large watershed to open water ratio of the Chesapeake ({approximately} 16:1), the net indirect loading may in fact be quite significant. A first step in assessing the importance of watershed transmission of atmospherically deposited trace elements is to estimate the annual integrated deposition to the watershed. This has been done using a statistical precipitation model developed at Pennsylvania State University, employing existing data from a number of studies. Wet deposition was estimated using flux measurements from 5 sites: Wye-Island, the Elms, Bear Branch and Haven Beach, VA. Dry deposition estimates are based on measured aerosol concentrations at several locations, using appropriate deposition velocities (V{sub d}) for land use specification produced by the Chesapeake Bay Program. Source attribution analysis of selected trace elements and major ions were based on seven years of precipitation event data from the Lewes, DE site using Chemical Mass Balance, factor analysis and air-mass back-trajectories.
- OSTI ID:
- 460470
- Report Number(s):
- CONF-961149-; TRN: IM9718%%51
- Resource Relation:
- Conference: 17. annual meeting of the Society of Environmental Toxicology and Chemistry: partnerships for the environment - science, education, and policy, Washington, DC (United States), 17-21 Nov 1996; Other Information: PBD: 1995; Related Information: Is Part Of SETAC 17. annual meeting -- Abstract book. Partnerships for the environment: Science, education, and policy; PB: 378 p.
- Country of Publication:
- United States
- Language:
- English
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