HR: 09:00h
AN: B11A-04    [PDF]
TI: Natural Organic Matter-Promoted Metal Inhibition of Hematite Bioreduction
AU: * Stone, J J
EM: James.Stone@sdsmt.edu
AF: South Dakota School of Mines and Technology, Dept of Civil and Environmental Engineering, 501 E. Saint Joseph St., Rapid City, SD 57701 United States
AU: Burgos, W D
EM: bburgos@psu.edu
AF: The Pennsylvania State University, Dept of Civil and Environmental Engineering, 212 Sackett Building, University Park, PA 16802 United States
AB: A developing technology for the in situ treatment of metal and radionuclide contaminants is the stimulation of dissimilatory metal-reducing bacteria (DMRB) to reduce solid phase iron oxides which promote Fe(II) induced chemical reduction of contaminants. Natural organic matter (NOM) can stimulate the biological reduction of solid-phase iron oxides by serving as an electron shuttle and by complexing biogenic Fe(II). The addition of NOM to contaminated zones has been proposed to further stimulate iron reduction and the fortuitous reduction and immobilization of contaminants. However, little research has been conducted on quarternary systems that contain DMRB, ferric oxides, NOM, and metals or radionuclides. The effect of zinc on the biological reduction of hematite and nitrate by the DMRB Shewanella putrefaciens strain CN32 was studied in the absence and presence of NOM. Nitrate was used to compare results between solid-phase and soluble electron acceptors. Previous work has demonstrated that, in the absence of zinc, NOM significantly enhanced hematite bioreduction but slightly inhibited nitrate reduction. In the absence of NOM, zinc was shown to significantly inhibit both hematite and nitrate bioreduction. In the presence of NOM, zinc inhibition of nitrate bioreduction was completely eliminated, presumably due to the NOMs' ability to complex Zn(II) and decrease Zn2+ activity. It was assumed that the presence of NOM would also decrease zinc inhibition of hematite reduction. Contrary to this hypothesis, NOM significantly increased the inhibitory effect of zinc during hematite bioreduction. In addition, non-toxic Mn(II) became inhibitory in the presence of NOM during hematite bioreduction. These results suggest that ternary Me(II)-NOM-oxide surface complexes may specifically inhibit solid-phase bioreduction. Thus, interactions between NOM and metal/radionuclide contaminants may effect the overall efficacy of the biostimulation remediation strategy.
DE: 0400 Biogeosciences
DE: 1055 Organic geochemistry
DE: 4840 Microbiology
SC: Biogeosciences [B]
MN: 2003 Fall Meeting