HR: 1340h
AN: B33A-0866    [Abstracts]
TI: Heavy Metal Contaminated Soils in Riverside Park, Milwaukee, WI: Character, Bioavailability, and Distribution
AU: * Dansand, J J
EM: dansandj@lawrence.edu
AF: Department of Geology Lawrence University, 115 S Drew St, Appleton, WI 54912, United States
AU: Knudsen, A C
EM: knudsena@lawrence.edu
AF: Department of Geology Lawrence University, 115 S Drew St, Appleton, WI 54912, United States
AB: Prior to being breached in 1990, the North Avenue Dam on the Milwaukee River had created a 2.5-mile impoundment for over 150 years. Upstream urban runoff and industrial pollution resulted in the deposition of heavy metal rich sediments in the slow moving waters of the impoundment. After the dam removal, the river returned to a more natural flowpath and as the river narrowed, newly exposed riverbed was annexed as part of Riverside Park, enabling ecological recovery efforts on the river and riparian zones. However, these newly exposed soils are enriched with heavy metal contaminants, most notably, Pb, Zn, Cd, Cu, and Ni, concentrated by the impoundment. The current study has analyzed the location and concentrations of these trace metals, as well as their mobility and availability. This study is being conducted in conjunction with the Urban Ecology Center, a nonprofit environmental organization located in Riverside Park that is dedicated to serving the local community and urban youth while restoring and protecting the natural areas along the Milwaukee River. Analyses have included determination of general soil parameters such as particle size, organic content, and point of zero charge analyses. Beyond bulk chemical analysis, we have conducted selective sequential extractions to estimate the chemical speciation of these elements, which showed that approximately 30 percent of contaminants are highly available. Additionally, the soils have been analyzed with an Electron Microprobe to directly observe phase relationships of metals in the soils. Microprobe and other analyses have shown that heavy metals are associated with a variety of phases, including Mn and Fe oxy-hydroxides, and vary in concentration and phase relationships with depth and distance from the river. Finally, a field-portable x-ray fluorescence spectrometer (pXRF), coupled with GPS data, is being used to create a geochemical map of heavy metal distributions throughout the park.
DE: 0744 Rivers (0483, 1856)
DE: 1039 Alteration and weathering processes (3617)
DE: 1090 Field relationships (3690, 8486)
DE: 1865 Soils (0486)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting