HR: 17:30h
AN: B24B-07    [Abstracts]
TI: A Novel Approach to Estimate the Distribution of Reducible Iron Within Different Pore Fractions of Structured Media.
AU: * Kamolpornwijit, W
EM: wka@ornl.gov
AF: Pacific Northwest National Laboratory, PO 999, Richland, WA 99354 United States
AU: Brooks, S C
EM: brookssc@ornl.gov
AF: Oak Ridge National Laboratory, PO 2008, Oak Ridge, TN 37831 United States
AU: Kim, Y
EM: kimy1@ornl.gov
AF: Oak Ridge National Laboratory, PO 2008, Oak Ridge, TN 37831 United States
AU: Scheibe, T D
EM: tim.scheibe@pnl.gov
AF: Pacific Northwest National Laboratory, PO 999, Richland, WA 99354 United States
AB: The success of bioremediation processes employing iron reducing bacteria depends on several factors; one of the crucial factors is the availability of Fe(III) as an electron acceptor. The iron content of subsurface media usually is obtained through different extraction techniques performed in a well-mixed batch experiment. For structured media where preferential flow prevails over the matrix flow, however, the iron content from homogenized samples may not well represent the iron content available for microbial activity. Results from the batch experiments may overestimate the availability of reducible iron. As microbes remain within the macro- and mesopores due to their cellular size restriction, the iron content within micropores may play an insignificant role during the biostimulation process. In this new approach, we extract Fe from different pore classes of intact cores of structured saprolite. The extracting solution (0.2 M ammonium oxalate) is introduced to an unsaturated column at specific tension. Unit gradient across the cores is maintained with a Marriotte device and vacuum chamber at the column inlet and outlet, respectively. Nonreactive tracers are included in the extractant solution to quantify transport properties. When the iron content in the effluent falls below detection limit, the tension is decreased (higher degree of saturation). The process is repeated until the column is operated at saturated conditions. The distribution of extractable iron within different pore fractions will be obtained directly from the experiment. In this study we will estimate the flow distribution, affected area, and mass concentration of iron using transport parameters obtained from non reactive tracer tests under both saturated and unsaturated conditions. The study will provide a novel approach supplementing the bulk extraction procedures which is critical to the success of bioremediation processes especially in structured media.
DE: 0418 Bioremediation
DE: 0461 Metals
DE: 1094 Instruments and techniques
DE: 1832 Groundwater transport
DE: 1865 Soils (0486)
SC: Biogeosciences [B]
MN: Fall Meeting 2005