HR: 0800h
AN: H51E-0823    [Abstracts]
TI: Developing Depositional Models for Mercury Contaminated Floodplain Deposits Using Geomorphic Mapping and GIS in South River, Virginia
AU: * Barbieri, A
EM: andreakb@udel.edu
AF: University of Delaware, Department of Geological Sciences, Newark, DE 19716, United States
AU: Pizzuto, J
EM: pizzuto@udel.edu
AF: University of Delaware, Department of Geological Sciences, Newark, DE 19716, United States
AU: O'Neal, M A
EM: michael@udel.edu
AF: University of Delaware, Department of Geography, Newark, DE 19716, United States
AU: Rhoades, E
EM: erhoades@udel.edu
AF: University of Delaware, Department of Geography, Newark, DE 19716, United States
AB: Mercury was introduced into the South River from the 1930s to the 1950s from an industrial plant in Waynesboro, Virginia. Mercury contamination in fish tissue continues to exceed acceptable levels. The contaminated sediments in the river's floodplains are probably the present source of mercury to the South River ecosystem. Locating and determining the extent and depositional history of these deposits are important for understanding the mercury cycle in the river as well as for remediation plans. The South River is a sinuous, single thread alluvial river with frequent bedrock exposures along its bed and banks. Overbank deposits are discontinuous and thin. Rates of lateral migration by the South River are extremely low, averaging 0.02 m/yr, and the river has been influenced by mill dams along a 19 km study reach. This 19 km section of the 37 km river reach was selected for the study because of its high concentration of Hg. Six different categories of floodplain deposits dating from 1937-2005 have been identified throughout the river using studies of historical aerial photographs in a GIS framework, field mapping, dendro- and radionuclide dating, grain size and Hg analysis. Not surprisingly, traditional depositional models of meandering rivers do not apply. Floodplain depositional units include mill dam deposits, point bar/bench deposits, concave bank bench deposits, islands, cattle deposits, and tributary confluences deposits. The most important deposits for sequestering historic mercury are those that also store the most silt and clay. These include mill dam deposits, point bar/bench deposits, concave bank deposits, and tributary confluence deposits. Many of these deposits represent reservoirs of mercury-contaminated sediments that could supply significant amounts of mercury into the river presently and in the future.
DE: 1819 Geographic Information Systems (GIS)
DE: 1820 Floodplain dynamics
DE: 1825 Geomorphology: fluvial (1625)
DE: 1834 Human impacts
SC: Hydrology [H]
MN: 2007 Fall Meeting