8 Matching Results

Search Results

Advanced search parameters have been applied.

Relating groundwater and sediment chemistry to microbial characterization at a BTEX-contaminated site

Description: The National Center for Manufacturing Science is investigating bioremediation of petroleum hydrocarbon at a site in Belleville, Michigan. As part of this study we examined the microbial communities to help elucidate biodegradative processes currently active at the site. We observed high densities of aerobic hydrocarbon degraders and denitrifiers in the less-contaminated sediments. Low densities of iron and sulfate reducers were measured in the same sediments. In contrast, the highly-contaminated sediments showed low densities of aerobic hydrocarbon degraders and denitrifiers and high densities of iron and sulfate reducers. Methanogens were also found in these highly-contaminated sediments. These contaminated sediments also showed a higher biomass, by phospholipid fatty acids, and greater ratios of phospholipid fatty acids which indicate stress within the microbial community. Aquifer chemistry analyses indicated that the more-contaminated area was more reduced and had lower sulfate than the less-contaminated area. These conditions suggest that the subsurface environment at the highly-contaminated area had progressed into sulfate reduction and methanogensis. The less-contaminated area, although less reduced, also appeared to be progressing into primarily iron- and sulfate-reducing microbial communities. The proposed treatment to stimulate bioremediation includes addition of oxygen and nitrate. Groundwater chemistry and microbial analyses revealed significant differences resulted from the injection of dissolved oxygen and nitrate in the subsurface. These differences included increases in pH and Eh and large decreases in BTEX, dissolved iron, and sulfate concentrations at the injection well.
Date: July 1996
Creator: Pfiffner, S. M.; Palumbo, A. V.; McCarthy, J. F. & Gibson, T.
Partner: UNT Libraries Government Documents Department

Subsurface microbial communities and degradative capacities during trichloroethylene bioremediation

Description: Subsurface amendments of air, methane, and nutrients were investigated for the in situ stimulation of trichloroethylene- degrading microorganisms at the US DOE Savannah River Integrated Demonstration. Amendments were injected into a lower horizontal well coupled with vacuum extraction from the vadose zone horizontal well. The amendments were sequenced to give increasingly more aggressive treatments. Microbial populations and degradative capacities were monitored in groundwaters samples bimonthly.
Date: December 31, 1995
Creator: Pfiffner, S.M.; Ringelberg, D.B.; Hedrick, D.B.; Phelps, T.J. & Palumbo, A.V.
Partner: UNT Libraries Government Documents Department

Apparatus and method for phosphate-accelerated bioremediation

Description: An apparatus and method for supplying a vapor-phase nutrient to contaminated soil for in situ bioremediation. The apparatus includes a housing adapted for containing a quantity of the liquid nutrient, a conduit in fluid communication with the interior of the housing, means for causing a gas to flow through the conduit, and means for contacting the gas with the liquid so that a portion thereof evaporates and mixes with the gas. The mixture of gas and nutrient vapor is delivered to the contaminated site via a system of injection and extraction wells configured to the site. The mixture has a partial pressure of vaporized nutrient that is no greater than the vapor pressure of the liquid. If desired, the nutrient and/or the gas may be heated to increase the vapor pressure and the nutrient concentration of the mixture. Preferably, the nutrient is a volatile, substantially nontoxic and nonflammable organic phosphate that is a liquid at environmental temperatures, such as triethyl phosphate or tributyl phosphate.
Date: January 1994
Creator: Looney, B. B.; Phelps, T. J.; Hazen, T. C.; Pfiffner, S. M.; Lombard, K. H. & Borthen, J. W.
Partner: UNT Libraries Government Documents Department

Using Artificial Neural Networks to Assess Changes in Microbial Communities

Description: We evaluated artificial neural networks (ANNs) as a technique for assessing changes in soil microbial communities following exposure to metals. We analyzed signature lipid biomarker (SLB) data collected from two soil microcosm experiments using traditional statistical techniques and ANN. Two phases of data analysis were done; pattern recognition and prediction. In general, the ANNs were better able to detect patterns and relationships in the SLB data than were the traditional statistical techniques.
Date: April 19, 1999
Creator: Brandt, C.C.; Macnaughton, S.; Palumbo, A.V.; Pfiffner, S.M. & Schryver, J.C.
Partner: UNT Libraries Government Documents Department

Using Artificial Neural Networks to Assess Microbial Communities

Description: We are evaluating artificial neural networks (ANNs) as tools for assessing changes in soil microbial communities following exposure to metals. We analyzed signature lipid biomarker data collected from two soil microcosm experiments using an autoassociative ANN. In one experiment, the microcosms were exposed to O, 100, or 250 ppm of metals, and in the other experiment the microcosms were exposed to O or 500 ppm of metals. The ANNs were able to distinguish between microcosms exposed and not exposed to metals in both experiments.
Date: September 8, 1998
Creator: Almeida, J.S.; Brand, C.C.; Palumbo, A.V.; Pfiffner, S.M. & Schryver, J.C.
Partner: UNT Libraries Government Documents Department

Influence of Other Contaminants on Natural Attenuation of Chlorinated Solvents

Description: Studies at numerous sites have shown high variability in the degradation rates of chlorinated solvents as measured by microcosm studies with <sup>14</sup>C labeled contaminants. The ability of nutrient and carbon additions to stimulate degradation can vary widely. Although some of these variations can be related to the structure of the extant microbial community, the presence of other less refractory contaminants may be critical fctors impacting the rate of chlorocarbon mineralization. Relaatively highe rates of TCE degradation have been observed in the DOE K-25 burial grounds with diverse organic loadings as well as in areas that show evidence for hydrocarbon contamination. Similarly, at other sites where there was TCE in the absence of hydrocarbons or other contaminants, the measured degradation rates have often been found to be very low. At various other sites, the intrasite variability in degradation rates appeared to be related to the presence of hydrocarbon contamination. The highest rates were observed at sites with evidence of hydrocarbons. These observations indicated that the viability of natural attenuation as a remediation option for chlorinated solvents might depend in part on the presence co-contaminants such as hydrocarbons or natural matter.
Date: April 19, 1999
Creator: Kinsall, B.L.; Palumbo, A.V.; Pfiffner, S.M.; Phelps, T.J. & Salpas, P.
Partner: UNT Libraries Government Documents Department

Phospholipid anaysis of extant microbiota for monitoring in situ bioremediation effectiveness

Description: Two sites undergoing bioremediation were studied using the signature lipid biomarker (SLB) technique. This technique isolates microbial lipid moieties specifically related to viable biomass and to both prokaryotic and eukaryotic biosynthetic pathways. The first site was a South Pacific atoll heavily contaminated with petroleum hydrocarbons. The second site was a mine waste reclamation area. The SLB technique was applied to quantitate directly the viable biomass, community structure, and nutritional/physiological status of the microbiota in the soils and subsurface sediments of these sites. All depths sampled at the Kwajalein Atoll site showed an increase in biomass that correlated with the co-addition of air, water, and nutrients. Monoenoic fatty acids increased in abundance with the nutrient amendment, which suggested an increase in gram-negative bacterial population. Ratios of specific phospholipid fatty acids indicative of nutritional stress decreased with the nutrient amendment. Samples taken from the mine reclamation site showed increases in total microbial biomass and in Thiobacillus biomass in the plots treated with lime and bactericide, especially when a cover soil was added. The plot treated with bactericide and buffered lime without the cover soil showed some decrease in Thiobacillus numbers, but was still slightly higher than that observed in the control plots.
Date: December 31, 1995
Creator: Pinkart, H.C.; Ringelberg, D.B.; Stair, J.O.; Sutton, S.D..; Pfiffner, S.M. & White, D.C.
Partner: UNT Libraries Government Documents Department