HR: 1340h
AN: H13G-1670    [Abstracts]
TI: The role of redox conditions in controlling arsenic release from a tailings aquifer
AU: * Schreiber, M E
EM: mschreib@vt.edu
AF: Department of Geosciences, Virginia Tech, 4044 Derring Hall, Blacksburg, VA 24061, United States
AB: At an abandoned arsenic mine both geology and hydrology play important roles in controlling redox conditions, which in turn influence arsenic release from minerals to groundwater. The shallow aquifer at the site is comprised of mine tailings, which contain a variety of arsenic-bearing minerals, including arsenopyrite, scorodite, and As-rich iron oxides. Based on sequential extraction, most of the As in the mine tailings (> 80%) is associated with iron oxides. Groundwater is microaerophillic but recharge introduces DO almost instantaneously to the shallow aquifer, which contributes to oxidation of arsenopyrite in the aquifer. Because conditions in the aquifer are not strongly reducing, release of As from iron oxides due to reductive dissolution does not appear to be a significant As release mechanism. However, desorption may play a role in releasing high concentrations (up to 5 mg/L) of arsenic to groundwater.
DE: 0489 Trace element cycling (4875)
DE: 1830 Groundwater/surface water interaction
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2007 Fall Meeting