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Other Microbial Genomics and Ecology
Projects
Project and Related Publications |
Funding for this project is from the Office of Science of the US Department of Energy.
Significant advances have been made in the ability to measure the composition of indigenous subsurface microbial communities. However, fundamental questions still persist concerning the interactive effects of geochemistry and community structure on metal reduction rates in the subsurface. Many microorganisms can change the subsurface geochemical conditions (e.g., cause a drop in redox) so metal reduction becomes an energetically favored reaction. Some microbes can directly catalyze the necessary reactions so that metal reduction occurs at a more rapid rate than without microbial activity. Many microorganisms can accomplish the first role but many fewer can accomplish the second. Physical and geochemical factors such as mass transport, oxygen level, and nitrate concentration will likely dominate the rate of microbial change in the redox potential. Thus, it is possible that the importance of community structure at this stage of metal reduction may be minimal. However, the effect of community composition on the rate of metal reduction may be important. We are using controlled laboratory experiment with sediments and groundwater from the NABIR Field Research Center (FRC) to compare the effects of manipulations designed to influence community structure (differences in electron donors) to those designed to influence geochemistry (presence of humics as electron shuttles) on uranium reduction. Also, the effect of carbon:phosphate ratios on community structure and uranium reduction rates will be examined in the context of resource-ratio theory to help predict the nutrient supply rates and ratios that maximize uranium reduction at the FRC site. In the final stage we will extend the research to other sites where toxic metals and radionuclides are problematic.
MicrocosmsWe are using laboratory microcosms containing sediments and groundwater collected from the Natural and Accelerated Bioremediation Research (NABIR) program Field Research Center (FRC) located at Oak Ridge National Laboratory. The FRC is contaminated with uranium and has high levels of nitrate and an acidic pH. Sediment samples are homogenized anaerobically prior to use in the microcosms.NABIR Related LinksNABIR Home Page NABIR Field Research Center DOE Office of Science US Department of Energy |
Figure 2.
Microcosms containing FRC site sediment and groundwater with additions
of substrates (methanol, ethanol, and glucose) and unamended control. |
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Project and Related Publications:
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ESD | Microbial Genomics and Ecology Research |
Anthony V. Palumbo, Environmental Sciences Division, P. O. Box 2008, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6038 |
Phone: (865)576-8002, Fax: (865)576-8646, E-mail: palumboav@ornl.gov |
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Revised May 23, 2005 |