HR: 0830h
AN: B41C-0888    [PDF]
TI: Reconstruction of Overbank Sedimentation Rates with Chromite Mining Waste in Small, Urbanizing Eastern Piedmont Watersheds (Baltimore, MD, USA)
AU: * Bain, D J
EM: dbain@jhu.edu
AF: Johns Hopkins University Department of Geography and Environmental Engineering, 3400 N. Charles St. Ames 313, Baltimore, MD 21218 United States
AU: Brush, G S
EM: dbain@jhu.edu
AF: Johns Hopkins University Department of Geography and Environmental Engineering, 3400 N. Charles St. Ames 313, Baltimore, MD 21218 United States
AB: Basin scale sediment dynamics continue to elude generalization, especially in areas where the agricultural transition preceded the advent of conventional data sources such as the decennial census and aerial photography. Studies of sediment accumulation in overbank areas are similarly impeded by the short temporal coverage of radio-isotopes (e.g., $^{137}$Cs $\sim$40 years and $^{210}$Pb $\sim$100 years) and the tendency of biomarkers to degrade in unsaturated overbank sediments. European settlement and associated land use transitions began $\sim$1730 in the Red Run basin, a small (2000 ha) drainage in western Baltimore County. Early chromite mining activity (1820-1880) introduced Cr contaminated sediments to the fluvial system during a rapid transition to agricultural land use (the peak of local agricultural activity is commonly estimated to be $\sim$1900). Sedimentation rates were reconstructed for a series of overbank cores using $^{137}$Cs techniques and Cr concentration stratigraphy dated with corresponding changes in mining activity. Sedimentation rates during 1820-1880 are 4-8x pre-1820 rates, 1-4x 1880-1963 rates and 2-8x post 1963 rates. These rates are compared with regional land use change/basin sediment dynamics models. Sediment accumulation in Red Run began earlier than regional models suggest and periods of peak sedimentation occurred before peak regional agricultural activity. These results indicate that floodplain sedimentation in Eastern Piedmont basins may have occurred much earlier than expected, leaving a legacy of buried sediments that continues to influence fluvial systems, especially as these areas undergo urbanization.
DE: 1065 Trace elements (3670)
DE: 1699 General or miscellaneous
DE: 1803 Anthropogenic effects
DE: 1824 Geomorphology (1625)
SC: Biogeosciences [B]
MN: 2003 Fall Meeting