ARSENIC CONTAMINATION IN SOUTHEAST WISCONSIN: SOURCES OF ARSENIC AND MECHANISMS OF ARSENIC MOBILIZATION
Ongoing work includes efforts to identify geologic and hydrogeologic controls on arsenic concentrations by comparing groundwater chemistry data to information about well construction, lithology, bedrock topography, stratigraphy, and groundwater flow regimes. Data sources for this analysis include existing groundwater chemistry data, archived core and cuttings samples, and well construction reports. Extensive groundwater sampling in arsenic-impacted areas will provide additional chemistry data. Detailed lithologic and mineralogic data will be obtained from core samples collected during rotasonic drilling.
Future work will include sequential extraction experiments on arsenic rich core samples to characterize the solid phases with which arsenic is associated. Bench-scale leaching experiments will be conducted to determine the chemical and environmental conditions that promote the mobilization of arsenic in the study area, and geochemical reaction models will be developed to further test hypotheses regarding processes controlling mobilization of arsenic. The results of this work will aid in developing guidelines for siting, constructing, and operating wells in a manner that prevents or reduces the likelihood of arsenic contamination.