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COMMUNITY DEVELOPMENT IN FRESHWATER MICROCOSMS

Description: Two cylindrical freshwater microcosms with a volume of 700 {ell} were maintained under controlled laboratory conditions for 190 days. The two microcosms were identical with regard to initial chemical composition and biological inocula, with the exceptions that in one microcosm (designated Tank 2) mosquitofish (Gambusia) and herbivorous catfish (Placostomas) were added. Three distinct communities developed in the tanks: (1) a phytoplankton-zooplankton assemblage and (2) two periphyton-zoobenthos communities associated with the sides and bottom of the tank, respectively. Community development and successional patterns were similar in both tanks. Major differences between the tanks involved timing of succession of the zooplankton and zoobenthos, attributable to predation by fish, principally Gambusia. A major drawback for these microcosms as use for experimental analogs such as lakes was a luxuriant periphyton growth which eventually overwhelmed the biomass of the system. The tanks displayed a degree of successional replicability, a large number of species, and a diversity of community development. Microcosms of this size could find use as experimental systems for higher level trophic manipulation and observation of life cycles not amenable to field studies.
Date: January 1, 1978
Creator: Rees, John T.
Partner: UNT Libraries Government Documents Department

Ecological Interactions Between Metals and Microbes

Description: Analyses of chromium resistant microbes. Culturable xylene-degrading and chromate-resistant microbes were obtained from chronically cocontaminated soil using a microcosm enrichment technique, and shown to correlate to dominant soil populations using culture independent techniques. The soil microbial community proved able to mount a respiratory response to addition of xylene in the presence of chromate. The majority of isolates belonged to the ubiquitous but poorly studied high %G+C Gram positive genus Arthrobacter, and exhibited considerable genotypic and phenotypic variability. Phenotypic assays uncovered a wide variation in the levels of chromate resistance, even between very closely related strains. Primers designed against conserved motifs in the known chrA chromate efflux gene failed to detect similar sequences among the chromate resistant Arthrobacter isolates obtained through enrichment.
Date: June 1, 2004
Creator: Konopka, Allan E.
Partner: UNT Libraries Government Documents Department

Bacterial quorum sensing and nitrogen cycling in rhizosphere soil

Description: Plant photosynthate fuels carbon-limited microbial growth and activity, resulting in increased rhizosphere nitrogen (N)-mineralization. Most soil organic N is macromolecular (chitin, protein, nucleotides); enzymatic depolymerization is likely rate-limiting for plant N accumulation. Analyzing Avena (wild oat) planted in microcosms containing sieved field soil, we observed increased rhizosphere chitinase and protease specific activities, bacterial cell densities, and dissolved organic nitrogen (DON) compared to bulk soil. Low-molecular weight DON (<3000 Da) was undetectable in bulk soil but comprised 15% of rhizosphere DON. Extracellular enzyme production in many bacteria requires quorum sensing (QS), cell-density dependent group behavior. Because proteobacteria are considered major rhizosphere colonizers, we assayed the proteobacterial QS signals acyl-homoserine lactones (AHLs), which were significantly increased in the rhizosphere. To investigate the linkage between soil signaling and N cycling, we characterized 533 bacterial isolates from Avena rhizosphere: 24% had chitinase or protease activity and AHL production; disruption of QS in 7 of 8 eight isolates disrupted enzyme activity. Many {alpha}-Proteobacteria were newly found with QS-controlled extracellular enzyme activity. Enhanced specific activities of N-cycling enzymes accompanied by bacterial density-dependent behaviors in rhizosphere soil gives rise to the hypothesis that QS could be a control point in the complex process of rhizosphere N-mineralization.
Date: October 1, 2008
Creator: DeAngelis, K. M.; Lindow, S. E. & Firestone, M. K.
Partner: UNT Libraries Government Documents Department

Horizontal gene transfer as adaptive response to heavy metal stress in subsurface microbial communities. Final report for period October 15, 1997 - October 15, 2000

Description: Horizontal gene transfer as adaptive response to heavy metal stress in the presence of heavy metal stress was evaluated in oligotrophic subsurface soil laboratory scale microcosms. Increasing levels of cadmium (10, 100 and 1000 mM) were applied and an E. coli donor was used to deliver the target plasmids, pMOL187 and pMOL222, which contained the czc and ncc operons, and the helper plasmid RP4. Plasmid transfer was evaluated through monitoring of the heavy metal resistance and presence of the genes. The interactive, clearly revealed, effect of biological and chemical external factors on the extent of plasmid-DNA propagation in microbial communities in contaminated soil environments was observed in this study. Additionally, P.putida LBJ 415 carrying a suicide construct was used to evaluate selective elimination of a plasmid donor.
Date: December 21, 2001
Creator: Smets, B. F.
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

Bioavailability of Fe(III) in natural soils and the impact on mobility of inorganic contaminants

Description: Inorganic contaminants, such as heavy metals and radionuclides, can adhere to insoluble Fe(III) minerals resulting in decreased mobility of these contaminants through subsurface environments. Dissimilatory Fe(III)-reducing bacteria (DIRB), by reducing insoluble Fe(III) to soluble Fe(II), may enhance contaminant mobility. The Savannah River Site, South Carolina (SRS), has been subjected to both heavy metal and radionuclide contamination. The overall objective of this project is to investigate the release of inorganic contaminants such as heavy metals and radionuclides that are bound to solid phase soil Fe complexes and to elucidate the mechanisms for mobilization of these contaminants that can be associated with microbial Fe(III) reduction. This is being accomplished by (i) using uncontaminated and contaminated soils from SRS as prototype systems, (ii) evaluating the diversity of DIRBs within the samples and isolating cultures for further study, (iii) using batch microcosms to evaluate the bioavailability of Fe(III) from pure minerals and SRS soils, (iv) developing kinetic and mass transfer models that reflect the system dynamics, and (v) carrying out soil column studies to elucidate the dynamics and interactions amongst Fe(III) reduction, remineralization and contaminant mobility.
Date: October 3, 2002
Creator: Kosson, David S.; Cowan, Robert M.; Young, Lily Y.; Hacherl, Eric L. & Scala, David J.
Partner: UNT Libraries Government Documents Department

STUDIES TO SUPPORT DEPLOYMENT OF EDIBLE OILS AS THE FINAL CVOC REMEDIATION IN T AREA SUMMARY REPORT

Description: The purpose of these studies was to determine the feasibility of using edible oils for remediation of the low but persistent chlorinated solvent (cVOC) groundwater contamination at the SRS T-Area. The following studies were completed: (1) Review of cVOC degradation processes and edible oil delivery for enhanced bioremediation. (2) Column studies to investigate placing neat oil on top of the water table to increase oil saturation and sequestration. (3) Analysis of T-Area groundwater geochemistry to determine the applicability of edible oils for remediation at this site. (4) Microcosm studies to evaluate biotic and abiotic processes for the T-Area groundwater system and evaluation of the existing microbial community with and with out soybean oil amendments. (5) Monitoring of a surrogate vadose zone site undergoing edible oil remediation at the SRS to understand partitioning and biotransformation products of the soybean oil. (6) Design of a delivery system for neat and emulsified edible oil deployment for the T-Area groundwater plume. A corresponding white paper is available for each of the studies listed. This paper provides a summary and overview of the studies completed for the remediation of the T-Area groundwater plume using edible oils. This report begins with a summary of the results and a brief description of the preliminary oil deployment design followed by brief descriptions of T-Area and current groundwater conditions as related to edible oil deployment. This is followed by a review of the remediation processes using edible oils and specific results from modeling, field and laboratory studies. Finally, a description of the preliminary design for full scale oil deployment is presented.
Date: October 31, 2006
Creator: Riha, B; Brian02 Looney, B; Miles Denham, M; Christopher Bagwell, C; Richard Hall, R & Carol Eddy-Dilek, C
Partner: UNT Libraries Government Documents Department

Ecological Interactions Between Metals and Microbes That Impact Bioremediation

Description: Previous work showed the correlation between bacterial biomass, population structure and the amount of lead, chromium and aromatic compounds present along a 21.6 m transect in which the concentrations of both heavy metals (Pb and Cr) and aromatic compounds varied 2-3 orders of magnitude. This work suggested that (a) biomass level was better correlated to the level of biodegradable organic C than the level of heavy metals, (b) microbial community composition differed between highly contaminated soils and uncontaminated ones, and (c) substantial microbial activity was found even in the highly contaminated soils. One confounding factor in these analyses was that the contaminated soils contained Pb, Cr, and aromatic hydrocarbons. Therefore, it was difficult to determine which factors were most important in the shifts of microbial community composition. Therefore, experiments were conducted in microcosms in which individual factors could be systematically varied. In this case, soils were used from the Seymour, IN site which had low levels of contamination, and the microbial community had little chance to adapt to heavy metals or aromatic compounds.
Date: June 1, 2003
Creator: Konopka, Allan E.
Partner: UNT Libraries Government Documents Department

Enhanced Microbial Pathways for Methane Production from Oil Shale

Description: Methane from oil shale can potentially provide a significant contribution to natural gas industry, and it may be possible to increase and continue methane production by artificially enhancing methanogenic activity through the addition of various substrate and nutrient treatments. Western Research Institute in conjunction with Pick & Shovel Inc. and the U.S. Department of Energy conducted microcosm and scaled-up reactor studies to investigate the feasibility and optimization of biogenic methane production from oil shale. The microcosm study involving crushed oil shale showed the highest yield of methane was produced from oil shale pretreated with a basic solution and treated with nutrients. Incubation at 30 C, which is the estimated temperature in the subsurface where the oil shale originated, caused and increase in methane production. The methane production eventually decreased when pH of the system was above 9.00. In the scaled-up reactor study, pretreatment of the oil shale with a basic solution, nutrient enhancements, incubation at 30 C, and maintaining pH at circumneutral levels yielded the highest rate of biogenic methane production. From this study, the annual biogenic methane production rate was determined to be as high as 6042 cu. ft/ton oil shale.
Date: February 15, 2009
Creator: Fallgren, Paul
Partner: UNT Libraries Government Documents Department

Microbial response to triepthylphosphate

Description: The effect of triethylphosphate (TEP) on the activity of a landfill aquifer microbial community was evaluated using standard techniques and in situ hybridizations with phylogenetic probes. Benzene was used as an external carbon source to monitor degradation of an aromatic compound in TEP amended microcosms. Microscopical and viable counts were higher in TEP containing microcosms when compared to unamended controls. A significant increase in metabolic activity was also observed for TEP amended samples as determined by the number of cells hybridizing to an eubacterial probe. In addition, the number of beta and gamma Proteobacteria increased from undetectable levels prior to the study to 15-29% of the total bacteria in microcosms containing TEP and benzene. In these microcosms, nearly 40% of the benzene was degraded during the incubation period compared to less than 5% in unamended microcosms. While TEP has previously been used as an alternate phosphate source in the bioremediation of chlorinated aliphatics, this study shows that it can also stimulate the microbial degradation of aromatics in phosphate limited aquifers.
Date: May 1, 1997
Creator: Hazen, T.C.; Santo Domingo, J.W. & Berry, C.J.
Partner: UNT Libraries Government Documents Department

Application of electrical methods to measure microbial activity in soils: Preliminary microcosm results

Description: The application of the geophysical technique known as self-potential to the measurement of microbial activity was tested on laboratory microcosms containing ferric iron and iron-reducing bacteria Shewanella alga BrY. Measurements of the electrical response of silver-coated copper electrodes distributed along a Teflon probe inserted into sterile and inoculated layers containing either ferric chloride, ferric citrate, or ferric oxide rich soil were recorded over hours or days. Strong electrical signals reached values more negative than {minus}400 mV for all types of inoculated ferric iron layers. Electric signals in sterile control layers, by contrast, rarely reached values more negative than {minus}150 mV. These preliminary experiments indicate that it may be possible to apply the self-potential geophysical method to monitor bioremediation in the field.
Date: December 1, 1997
Creator: Cox, B.L. Sweet, A. & Majer, E.
Partner: UNT Libraries Government Documents Department

Behavior of Dense, Immiscible Solvents in Fractured Clay-rich Soils

Description: This research program addresses the nature and distribution of chlorinated solvent DNAPL sources in fractured clays and weathered shales, and the potential for natural attenuation of plumes derived from these sources. Specific objectives include: (1) Investigate the factors controlling migration of chlorinated solvent DNAPLs in fine-grained, highly structured soils and weathered shale bedrock. (2) Investigate the influence of ''matrix diffusion'' on the dissolution and apparent disappearance of residual DNAPL. (3) Investigate potential for biodegradation of chlorinated solvents in fractured and weathered shales at an existing contaminated field site and through the use of laboratory studies in microcosms and undisturbed columns of fractured shale saprolite. (4) Comparison of DNAPL behavior in different types of fractured clay-rich materials.
Date: June 1, 2000
Creator: McKay, Larry D.; Sanseverino, John; Jardine, Phillip M.; Brooks, Scott C.; Cherry, John A. & Parker, Beth L.
Partner: UNT Libraries Government Documents Department

Ecological Interactions Between Metals and Microbes That Impact Bioremediation

Description: Samples have been obtained from (a) soil highly contaminated with Cr (tannery site) and (b) soils contaminated with petroleum, Cr, and Pb (Seymour, IN). Microcosm experiments with the tannery site soil indicated that microbial biomass (assayed as phospholipid-phosphate) and activity (assayed as carbon dioxide evolution) were primarily determined by organic carbon availability, but not total Cr concentration. The toxicity of metals to the indigenous microbial populations of the Seymour soils was determined by measuring microbial activity (incorporation of tritiated leucine into protein) of cells extracted from soil particles in solutions of increasing metal concentration. Although total Cr concentration varied 100-fold in these soils, the inhibition constant for Cr toxicity varied &lt; 3-fold. Of additional interest in one soil was the dose-response function; the response suggests the soil contains a complex mixture of microbes with different Cr resistance levels. Cr and Pb resistant bacteria have been isolated from these soil samples. In Arthrobacter sp. Cr15, Cr resistance was spontaneously lost at a frequency of ca. 0.5% after growth for 20 generations in non-selective medium. The wild-type contained a 60 kb plasmid. In two Cr sensitive strains, restriction fragment analysis has shown that 15 kb of the plasmid have been lost. Matings between the wild type and cured strains result in transfer of the Cr resistance phenotype at a frequency of 1%.
Date: June 1, 1998
Creator: Konopka, Allan E.
Partner: UNT Libraries Government Documents Department

RHIZOSPHERE MICROBIOLOGY OF CHLORINATED ETHENE CONTAMINATED SOILS: EFFECTS ON PHOSPHOLIPID FATTY ACID CONTENT

Description: Microbial degradation of chlorinated ethenes (CE) in rhizosphere soils was investigated at seepline areas impacted by CE plumes. Successful bioremediation of CE in rhizosphere soils is dependent on microbial activity, soil types, plant species, and groundwater CE concentrations. Seepline soils were exposed to trichloroethylene (TCE) and perchloroethylene (PCE) in the 10-50 ppb range. Greenhouse soils were exposed to 2-10 ppm TCE. Plants at the seepline were poplar and pine while the greenhouse contained sweet gum, willow, pine, and poplar. Phospholipid fatty acid (PLFA) analyses were performed to assess the microbial activity in rhizosphere soils. Biomass content was lowest in the nonvegetated control soil and highest in the Sweet Gum soil. Bacterial rhizhosphere densities, as measured by PLFA, were similar in different vegetated soils while fungi biomass was highly variable. The PLFA soil profiles showed diverse microbial communities primarily composed of Gram-negative bacteria. Adaptation of the microbial community to CE was determined by the ratio of {omega}7t/{omega}7c fatty acids. Ratios (16:1{omega}7v16:1{omega}7c and 18:l{omega}7t/18:1{omega}7c) greater than 0.1 were demonstrated in soils exposed to higher CE concentrations (10-50 ppm), indicating an adaptation to CE resulting in decreased membrane permeability. Ratios of cyclopropyl fatty acids showed that the vegetated control soil sample contained the fastest microbial turnover rate and least amount of environmental stress. PLFA results provide evidence that sulfate reducing bacteria (SRB) are active in these soils. Microcosm studies with these soils showed CE dechlorinating activity was occurring. This study demonstrates microbial adaptation to environmental contamination and supports the application of natural soil rhizosphere activity as a remedial strategy.
Date: May 26, 2005
Creator: Brigmon, R. L.; Stanhopc, A.; Franck, M. M.; McKinsey, P. C. & Berry, C. J.
Partner: UNT Libraries Government Documents Department

Novel imaging techniques, integrated with mineralogical, geochemical and microbiological characterizations to determine the biogeochemical controls on technetium mobility in FRC sediments

Description: The objective of this research program was to take a highly multidisciplinary approach to define the biogeochemical factors that control technetium (Tc) mobility in FRC sediments. The aim was to use batch and column studies to probe the biogeochemical conditions that control the mobility of Tc at the FRC. Background sediment samples from Area 2 (pH 6.5, low nitrate, low {sup 99}Tc) and Area 3 (pH 3.5, high nitrate, relatively high {sup 99}Tc) of the FRC were selected (http://www.esd.ornl.gov/nabirfrc). For the batch experiments, sediments were mixed with simulated groundwater, modeled on chemical constituents of FRC waters and supplemented with {sup 99}Tc(VII), both with and without added electron donor (acetate). The solubility of the Tc was monitored, alongside other biogeochemical markers (nitrate, nitrite, Fe(II), sulfate, acetate, pH, Eh) as the 'microcosms' aged. At key points, the microbial communities were also profiled using both cultivation-dependent and molecular techniques, and results correlated with the geochemical conditions in the sediments. The mineral phases present in the sediments were also characterized, and the solid phase associations of the Tc determined using sequential extraction and synchrotron techniques. In addition to the batch sediment experiments, where discrete microbial communities with the potential to reduce and precipitate {sup 99}Tc will be separated in time, we also developed column experiments where biogeochemical processes were spatially separated. Experiments were conducted both with and without amendments proposed to stimulate radionuclide immobilization (e.g. the addition of acetate as an electron donor for metal reduction), and were also planned with and without competing anions at high concentration (e.g. nitrate, with columns containing Area 3 sediments). When the columns had stabilized, as determined by chemical analysis of the effluents, we used a spike of the short-lived gamma emitter {sup 99m}Tc (50-200 MBq; half life 6 hours) and its mobility was monitored using a {gamma}-camera. ...
Date: February 3, 2009
Creator: Lloyd, Jonathan R.
Partner: UNT Libraries Government Documents Department

Subtask 1.22 - Microbial Cycling of CH4, CO2, and N2O in a Wetlands Environment

Description: Soil microbial metabolic activities play an important role in determining CO{sub 2}, CH{sub 4}, and N{sub 2}O fluxes from terrestrial ecosystems. To verify and evaluate CO{sub 2} sequestration potential by wetland restoration in the Prairie Pothole Region (PPR), as well as to address concern over restoration effects on CH{sub 4} and N{sub 2}O emissions, laboratory and in situ microcosm studies on microbial cycling of CO{sub 2}, CH{sub 4}, and N{sub 2}O were initiated. In addition, to evaluate the feasibility of the use of remote sensing to detect soil gas flux from wetlands, a remote-sensing investigation was also conducted. Results of the laboratory microcosm study unequivocally proved that restoration of PPR wetlands does sequester atmospheric CO{sub 2}. Under the experimental conditions, the simulated restored wetlands did not promote neither N{sub 2}O nor CH{sub 4} fluxes. Application of ammonia enhanced both N{sub 2}O and CH{sub 4} emission, indicating that restoration of PPR wetlands may reduce both N{sub 2}O and CH{sub 4} emission by cutting N-fertilizer input. Enhancement of CO{sub 2} emission by the N-fertilizer was observed, and this observation revealed an overlooked fact that application of N-fertilizer may potentially increase CO{sub 2} emission. In addition, the CO{sub 2} results also demonstrate that wetland restoration sequesters atmospheric carbon not only by turning soil conditions from aerobic to anoxic, but also by cutting N-fertilizer input that may enhance CO{sub 2} flux. The investigation on microbial community structure and population dynamics showed that under the experimental conditions restoration of the PPR wetlands would not dramatically increase population sizes of those microorganisms that produce N{sub 2}O and CH{sub 4}. Results of the in situ study proved that restoration of the PPR wetland significantly reduced CO{sub 2} flux. Ammonia enhanced the greenhouse gas emission and linearly correlated to the CO{sub 2} flux within the experimental rate range ...
Date: December 31, 2008
Creator: Ye, Dingyi; Kurz, Bethany & Kurz, Marc
Partner: UNT Libraries Government Documents Department

Field Evidence for Co-Metabolism of Trichloroethene Stimulated by Addition of Electron Donor to Groundwater

Description: For more than 10 years, electron donor has been injected into the Snake River aquifer beneath the Test Area North site of the Idaho National Laboratory for the purpose of stimulating microbial reductive dechlorination of trichloroethene (TCE) in groundwater. This has resulted in significant TCE removal from the source area of the contaminant plume and elevated dissolved CH4 in the groundwater extending 250 m from the injection well. The delta13C of the CH4 increases from 56o/oo in the source area to -13 o/oo with distance from the injection well, whereas the delta13C of dissolved inorganic carbon decreases from 8 o/oo to -13 o/oo, indicating a shift from methanogenesis to methane oxidation. This change in microbial activity along the plume axis is confirmed by PhyloChip microarray analyses of 16S rRNA genes obtained from groundwater microbial communities, which indicate decreasing abundances of reductive dechlorinating microorganisms (e.g., Dehalococcoides ethenogenes) and increasing CH4-oxidizing microorganisms capable of aerobic co-metabolism of TCE (e.g., Methylosinus trichosporium). Incubation experiments with 13C-labeled TCE introduced into microcosms containing basalt and groundwater from the aquifer confirm that TCE co-metabolism is possible. The results of these studies indicate that electron donor amendment designed to stimulate reductive dechlorination of TCE may also stimulate co-metabolism of TCE.
Date: May 17, 2010
Creator: Conrad, Mark E.; Brodie, Eoin L.; Radtke, Corey W.; Bill, Markus; Delwiche, Mark E.; Lee, M. Hope et al.
Partner: UNT Libraries Government Documents Department

Biodegradation of BTEX and Other Petroleum Hydrocarbons by Enhanced and Controlled Sulfate Reduction

Description: High concentrations of sulfide in the groundwater at a field site near South Lovedale, OK, were inhibiting sulfate reducing bacteria (SRB) that are known to degrade contaminants including benzene, toluene, ethylbenzene, and m+p-xylenes (BTEX). Microcosms were established in the laboratory using groundwater and sediment collected from the field site and amended with various nutrient, substrate, and inhibitor treatments. All microcosms were initially amended with FeCl{sub 2} to induce FeS precipitation and, thereby, reduce sulfide concentrations. Complete removal of BTEX was observed within 39 days in treatments with various combinations of nutrient and substrate amendments. Results indicate that elevated concentration of sulfide is a limiting factor to BTEX biodegradation at this site, and that treating the groundwater with FeCl{sub 2} is an effective remedy to facilitate and enhance BTEX degradation by the indigenous SRB population. On another site in Moore, OK, studies were conducted to investigate barium in the groundwater. BTEX biodegradation by SRB is suspected to mobilize barium from its precipitants in groundwater. Data from microcosms demonstrated instantaneous precipitation of barium when sulfate was added; however, barium was detected redissolving for a short period and precipitating eventually, when active sulfate reduction was occurring and BTEX was degraded through the process. SEM elemental spectra of the evolved show that sulfur was not present, which may exclude BaSO{sub 4} and BaS as a possible precipitates. The XRD analysis suggests that barium probably ended in BaS complexing with other amorphous species. Results from this study suggest that SRB may be able to use the sulfate from barite (BaSO{sub 4}) as an electron acceptor, resulting in the release of free barium ions (Ba{sup 2+}), and re-precipitate it in BaS, which exposes more toxicity to human and ecological health.
Date: July 1, 2007
Creator: Jin, Song
Partner: UNT Libraries Government Documents Department

Novel Imaging Techniques, Integrated with Mineralogical, Geochemical and Microbiological Characterization to Determine the Biogeochemical Controls....

Description: Tc(VII) will be reduced and precipitated in FRC sediments under anaerobic conditions in batch experiments (progressive microcosms). The complementary microcosm experiments using low pH/nigh nitrate sediments from 3 (near FW 009) are imminent, with the sediment cores already shipped to Manchester. HYPOTHESIS 2. Tc(VII) reduction and precipitation can be visualized in discrete biogeochemical zones in sediment columns using 99mTc and a gamma-camera. Preliminary experiments testing the use of 99mTc as a radiotracer to address hypotheses 2 and 3 have suggested that the 99mTc associates with Fe(II)-bearing sediments in microcosms and stratified columns containing FRC sediments. Initial proof of concept microcosms containing Fe(II)-bearing, microbially-reduced FRC sediments were spiked with 99mTc and imaged using a gamma-camera. In comparison with oxic controls, 99mTc was significantly partitioned in the solid phase in Fe(III)-reducing sediments in batch experiments. Column experiments using FRC background area soil with stratified biogeochemical zones after stimulation of anaerobic processes through nutrient supplementation, suggested that 99mTc transport was retarded through areas of Fe(III) reduction. HYPOTHESIS 3. Sediment-bound reduced 99mTc can be solubilized by perturbations including oxidation coupled to biological nitrate reduction, and mobilization visualized in real-time using a gamma-camera. Significant progress has been made focusing on the impact of nitrate on the biogeochemical behavior of technetium. Additions of 100 mM nitrate to FRC sediment microcosms, which could potentially compete for electrons during metal reduction, inhibited the reduction of both Fe(III) and Tc(VII) completely. Experiments have also addressed the impact of high nitrate concentrations on Fe(II) and Tc(IV) in pre-reduced sediments, showing no significant resolubilization of Tc with the addition of 25 mM nitrate. A parallel set of experiments addressing the impact of aerobic conditions on the stability/solubility of Fe(II) and Tc(IV), found 80 % resolubilization of the Tc. Column experiments exploring this behavior are being planned. HYPOTHESIS 4 The mobility of ...
Date: June 1, 2005
Creator: Lloyd, Jonathan R.
Partner: UNT Libraries Government Documents Department

Energy recovery through termites. Final report

Description: This project, Energy Recovery Through Termites, was based on the proposed development of an energy recovery system to produce low cost animal protein for use in animal feeds. The result of my study shows that to date we are unable to establish viable colonies of termites. This is based on several key factors as follows: (a) inability to capture reproductives to establish new colonies in a confined area needed to offer recovery or harvest of protein; (b) confinement of colonies (even without queen or reproductives) has proven to be far too complex to establish in low cost and modest facilities; (c) the proposal is not cost effective. The resources of skill and materials could not be repaid from the protein recovered.
Date: December 15, 1981
Creator: Granger, J.A.
Partner: UNT Libraries Government Documents Department

Rapid Mass Spectrometric DNA Diagnostics for Assessing Microbial Community Activity During Bioremediation

Description: Changes in pollutant profiles observed in contaminated soils have been attributed to biological activity when in actuality abiotic processes caused pollutant removal.1 This sometimes casual implication of biodegradation is not acceptable, but understandable, because factors which cause the disappearance of pollutants are not always easy to identify. Several pollutant removal or transformation pathways are possible with most pollutants found in soil and these processes may or may not operate independently. Careful evaluation of bioremediation necessitates that all transformation and removal pathways are anticipated so that the pathways are either controlled or monitored but in practice this is generally not possible. The diminution in pollutant oxidation might track with several candidate loss mechanisms and when this occurs the real cause becomes problematic to pin point. Many factors disguise or prevent the effectual tracking of bioremediation processes among which are three general types of problems: (1) The estimate that only about 0.1% or less of the microorganisms living in soils are culturable leads to the conclusion that the possibility for unknown organisms participating in a biodegradation pathway is high. How should these imperceptible microorganisms be tracked? (2) The diversity of the microcosm is large, yet several different genera have been shown to possess the same or very similar enzymes for degrading a pollutant. Cell counts of specific organisms, therefore may not track very well with the rate of loss or conversion of a pollutant. Should groups of organisms possessing similar biochemical reaction capabilities become the focus or is it more useful to track specific organisms? (3) Abiotic processes such as physical processes which transport pollutants away from a contamination site lead sometimes to the counterfactual conclusion that bioremediation occurred when in actuality the pollutant was diluted or dispersed heterogeneously. How do we handle a large number of samples so that significantly representative ...
Date: December 31, 1999
Creator: Benner, W. Henry; Hunter-Cevera, Jennie; Jaklevic, Joseph M. & Torok, Tamas
Partner: UNT Libraries Government Documents Department

Rapid Mass Spectrometric DNA Diagnostics for Assessing Microbial Community Activity During Bioremediation

Description: Changes in pollutant profiles observed in contaminated soils have been attributed to biological activity when in actuality abiotic processes caused pollutant removal.1 This sometimes casual implication of biodegradation is not acceptable, but understandable, because factors which cause the disappearance of pollutants are not always easy to identify. Several pollutant removal or transformation pathways are possible with most pollutants found in soil and these processes may or may not operate independently. Careful evaluation of bioremediation necessitates that all transformation and removal pathways are anticipated so that the pathways are either controlled or monitored but in practice this is generally not possible. The diminution in pollutant oxidation might track with several candidate loss mechanisms and when this occurs the real cause becomes problematic to pin point. Many factors disguise or prevent the effectual tracking of bioremediation processes among which are three general types of problems: (1) The estimate that only about 0.1% or less of the microorganisms living in soils are culturable leads to the conclusion that the possibility for unknown organisms participating in a biodegradation pathway is high. How should these imperceptible microorganisms be tracked? (2) The diversity of the microcosm is large, yet several different genera have been shown to possess the same or very similar enzymes for degrading a pollutant. Cell counts of specific organisms, therefore may not track very well with the rate of loss or conversion of a pollutant. Should groups of organisms possessing similar biochemical reaction capabilities become the focus or is it more useful to track specific organisms? (3) Abiotic processes such as physical processes which transport pollutants away from a contamination site lead sometimes to the counterfactual conclusion that bioremediation occurred when in actuality the pollutant was diluted or dispersed heterogeneously. How do we handle a large number of samples so that significantly representative ...
Date: December 31, 1999
Creator: Benner, W. Henry; Hunter-Cevera, Jennie & Jaklevic, Joseph M.
Partner: UNT Libraries Government Documents Department

Behavior of Dense, Immiscible Solvents in Fractured Clay-Rich Soils

Description: This research program addresses the nature and distribution of chlorinated solvent DNAPL sources in fractured clays and weathered shales and the potential for natural attenuation of plumes derived from these sources. These investigations are needed to build the scientific framework for assessment of DNAPL fate in fractured clays and remediation or control options. Specific objectives include: 1. Determine whether chlorinated solvent DNAPLs are likely to enter fractures and/or fine matrix pores for a typical DNAPL spill scenario and determine how DNAPL will be distributed in the soil, using capillary pressure - saturation experiments in large undisturbed columns of fractured shale saprolite. 2. Determine whether values of fracture aperture and fracture porosity derived from the ''cubic law'' are useful indicators of DNAPL entry pressure and residual saturation. 3. Investigate the influence of ''matrix diffusion'' on the dissolution and apparent disappearance of residual DNAPL (t his mechanism can cause more rapid dissolution and spreading of the DNAPL, but does not actually cause disappearance of the contaminant). 4. Investigate potential for biodegradation of chlorinated solvents in fractured and weathered shales at an existing contaminated field site and through the use of laboratory studies in microcosms and undisturbed columns of fractured shale saprolite. 5. Comparison of DNAPL behavior in different types of fractured clay-rich materials, primarily clay-rich shale saprolite in east Tennessee, and clay-rich tills in southwestern Ontario.
Date: June 1, 1999
Creator: McKay, Larry D.; Jardine, Philip; Cherry, John A.; Sanseverino, John; Brooks, Scott & Parker, Beth L.
Partner: UNT Libraries Government Documents Department

Experimental terrestrial soil-core microcosm test protocol. A method for measuring the potential ecological effects, fate, and transport of chemicals in terrestrial ecosystems

Description: In order to protect the environment properly and have a realistic appraisal of how a chemical will act in the environment, tests of ecological effects and chemical fate must be performed on complex assemblages of biotic and abiotic components (i.e., microcosms) as well as single species. This protocol is one which could be added to a series of tests recently developed as guidelines for Section 4 of the Toxic Substances Control Act (P.L. 94-469; U.S.C., Section 2601-2629). The terrestrial soil-core microcosm is designed to supply site-specific and possibly regional information on the probable chemical fate and ecological effects resulting from release of a chemical substance to a terrestrial ecosystem. The EPA will use the data resulting from this test system to compare the potential hazards of a chemical with others that have been previously evaluated.
Date: June 1, 1985
Creator: Van Voris, P.; Tolle, D.A. & Arthur, M.F.
Partner: UNT Libraries Government Documents Department