Download or read book Vadose Zone Microbial Community Structure and Activity in Metal radionuclide Contaminated Sediments Final Technical Report written by and published by . This book was released on 2002 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: This final technical report describes the research carried out during the final two months of the no-cost extension ending 11/14/01. The primary goals of the project were (1) to determine the potential for transformation of Cr(VI) (oxidized, mobile) to Cr(III) (reduced, immobile) under unsaturated conditions as a function of different levels and combinations of (a) chromium, (b) nitrate (co-disposed with Cr), and (c) molasses (inexpensive bioremediation substrate), and (2) to determine population structure and activity in experimental treatments by characterization of the microbial community by signature biomarker analysis and by RT-PCR and terminal restriction fragment length polymorphism (T-RFLP) and 16S ribosomal RNA genes. It was determined early in the one-year no-cost extension period that the T-RFLP approach was problematic in regard to providing information on the identities of microorganisms in the samples examined. As a result, it could not provide the detailed information on microbial community structure that was needed to assess the effects of treatments with chromium, nitrate, and/or molasses. Therefore, we decided to obtain the desired information by amplifying (using TR-PCR, with the same primers used for T-RFLP) and cloning 16S rRNA gene sequences from the same RNA extracts that were used for T-RFLP analysis. We also decided to use a restriction enzyme digest procedure (fingerprinting procedure) to place the clones into types. The primary focus of the research carried out during this report period was twofold: (a) to complete the sequencing of the clones, and (b) to analyze the clone sequences phylogenetically in order to determine the relatedness of the bacteria detected in the samples to each other and to previously described genera and species.

Download or read book Vadose Zone Microbial Community Structure and Activity in Metal written by and published by . This book was released on 2002 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: This final technical report describes the research carried out during the final two months of the no-cost extension ending 11/14/01. The primary goals of the project were (1) to determine the potential for transformation of Cr(VI) (oxidized, mobile) to Cr(III) (reduced, immobile) under unsaturated conditions as a function of different levels and combinations of (a) chromium, (b) nitrate (co-disposed with Cr), and (c) molasses (inexpensive bioremediation substrate), and (2) to determine population structure and activity in experimental treatments by characterization of the microbial community by signature biomarker analysis and by RT-PCR and terminal restriction fragment length polymorphism (T-RFLP) and 16S ribosomal RNA genes. It was determined early in the one-year no-cost extension period that the T-RFLP approach was problematic in regard to providing information on the identities of microorganisms in the samples examined. As a result, it could not provide the detailed information on microbial community structure that was needed to assess the effects of treatments with chromium, nitrate, and/or molasses. Therefore, we decided to obtain the desired information by amplifying (using TR-PCR, with the same primers used for T-RFLP) and cloning 16S rRNA gene sequences from the same RNA extracts that were used for T-RFLP analysis. We also decided to use a restriction enzyme digest procedure (fingerprinting procedure) to place the clones into types. The primary focus of the research carried out during this report period was twofold: (a) to complete the sequencing of the clones, and (b) to analyze the clone sequences phylogenetically in order to determine the relatedness of the bacteria detected in the samples to each other and to previously described genera and species.

Download or read book Microbial Characterization of a Radionuclide and Metal contaminated Waste Site written by and published by . This book was released on 1993 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: The operation of nuclear processing facilities and defense-related nuclear activities has resulted in contamination of near-surface and deep-subsurface sediments with both radionuclides and metals. The presence of mixed inorganic contaminants may result in undetectable microbial populations or microbial populations that are different from those present in uncontaminated sediments. To determine the impact of mixed radionuclide and metal contaminants on sediment microbial communities, we sampled a processing pond that was used from 1948 to 1975 for the disposal of radioactive and metal-contaminated wastewaters from laboratories and nuclear fuel fabrication facilities on the Hanford Site in Washington State. Because the Hanford Site is located in a semiarid environment with average rainfall of 159 mm/year, the pond dried and a settling basin remained after wastewater input into the pond ceased in 1975. This processing pond basin offered a unique opportunity to obtain near-surface sediments that had been contaminated with both radionuclides and metals for several decades. Our objectives were to determine the viable populations of microorganisms in the sediments and to test several hypotheses about how the addition of both radionuclides and metals influenced the microbial ecology of the sediments. Our first hypothesis was that viable populations of microorganisms would be lower in the more contaminated sediments. Second, we expected that long-term metal exposure would result in enhanced metal resistance. Finally, we hypothesized that microorganisms from the most radioactive sediments should have had enhanced radiation resistance.

Download or read book Structure and Function of Microbial Communities Controlling the Fate and Transformation of U VI in Radionuclide Contaminated Subsurface Sediments written by Denise Marie Akob and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A polyphasic approach employing microbiological and geochemical techniques was used in this dissertation to link the structure and function of microbial communities in subsurface sediments of the U.S. Department of Energy's Oak Ridge Field Research Center (ORFRC), in Oak Ridge, Tennessee. Subsurface sediments at the ORFRC site are cocontaminated with high levels of U(VI) and nitrate and microbial activity is limited by carbon availability and variable pH. The conditions at the ORFRC site are representative of many radionuclide-contaminated sites; therefore, results from this dissertation will have broader significance for development of bioremediation strategies that can be employed worldwide.

Download or read book Potential for Microbial Stimulation in Deep Vadose Zone Sediments by Gas Phase Nutrients written by F. J. Brockman and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Viable microbial populations are low, typically 10{sup 4} cells per gram, in deep vadose zones in arid climates. There is evidence that microbial distribution in these environments is patchy. In addition, infiltration or injection of nutrient-laden water has the potential to spread and drive contaminants downward to the saturated zone. For these reasons, there are uncertainties regarding the feasibility of bioremediation of recalcitrant contaminants in deep vadose zones. The objectives of this study were to investigate the occurrence of denitrifying activity and gaseous carbon-utilizing activity in arid-climate deep vadose zone sediments contaminated with, and/or affected by past exposure to, carbon tetrachloride (CT). These metabolisms are known to degrade CT and/or its breakdown product chloroform under anoxic conditions. A second objective was to determine if CT would be degraded in these sediments under unsaturated, bulk-phase aerobic incubation conditions. Both denitrifier population (determined by MPN) and microbial heterotrophic activity (measured by mineralization of 14-C labeled glucose and acetate) were relatively low and the sediments with greater in situ moisture (10-21% versus 2-7%) tended to have higher activities. When sediments were amended with gaseous nutrients (nitrous oxide and triethyl/tributyl phosphate) and gaseous C sources (a mixture of methane, ethane, propylene, propane, and butane) and incubated for 6 months, approximately 50% of the samples showed removal of one or more gaseous C sources, with butane most commonly used (44% of samples), followed by propylene (42%), propane (31%), ethane (22%), and methane (4%). Gaseous N and gaseous P did not stimulate removal of gaseous C substrates compared to no addition of N and P. CT and gaseous C sources were spiked into the sediments that removed gaseous C sources to determine if hydrocarbon-degraders have the potential to degrade CT under unsaturated conditions. In summary, gaseous C sources--particularly butane and propylene--have promise for increasing the numbers and activity of indigenous microbial populations in arid-climate deep vadose zone sediments.

Download or read book Vadose Zone Processes written by John S. Selker and published by CRC Press. This book was released on 1999-06-28 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vadose Zone Processes provides a unified, up-to-date treatment on the movement of water through unsaturated media. In addition to covering the basic equations governing the flow and fate of water in unsaturated media, the text covers the biogeochemistry of vadose environments and the statistical description of vadose processes. The authors emphasize maintaining an intuitive understanding of how the results are derived and how they are appropriately applied. This comprehensive and important book will be useful not only to those in traditional fields such as civil engineering, geology, crop science, chemical engineering, agricultural engineering, and hydrology but also in the newer environmental engineering fields including containment transport, pollution remediation, and waste disposal.

Download or read book Integrated Field Laboratory and Modeling Studies to Determine the Effects of Linked Microbial and Physical Spatial Heterogeneity on Engineered Vadose Zone Bioremediation written by and published by . This book was released on 2003 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: While numerous techniques exist for remediation of contaminant plumes in groundwater or near the soil surface, remediation methods in the deep vadose zone are less established due to complex transport dynamics and sparse microbial populations. Yet pollution in the vadose zone poses a serious threat to the groundwater resources lying deeper in the sediment. While the contaminant may be slowly degraded by native microbial communities; microbial degradation rates rarely keep pace with the spread of the pollutant. Hydrologic and microbiological properties of the zone, and their interactions, are fundamentally different from the saturated zone: the vadose zone has an additional phase (air), higher levels of oxygen, and contaminant transport and water movement is predominantly perpendicular to geologic strata and occurs in water films. In addition, microbial populations in the vadose zone are sparse and spatially discontinuous, especially in arid climates. At the Department of Energy's Hanford site in Richland, WA, numerous recalcitrant organic compounds were disposed of in the vadose zone, and now are continual sources of groundwater pollution. Among the most problematic of these is a plume of carbon tetrachloride (CT), a common solvent, the majority of which still resides in the vadose zone despite the presence of microbes that can degrade it and its byproduct chloroform. Gaseous nutrients can in principle be used to stimulate the native degrading population and has shown some promise in isolated field cases. However, there is a lack of knowledge on how physical and hydrologic features of the vadose zone control the spatial distribution of microbes, and the extent that microbes can colonize the vadose zone in response to nutrient delivery during bioremediation. The overall objective of the project was to increase knowledge of the feasibility of engineered bioremediation in the deep vadose zone, particularly at arid western sites where microbial populations and activities are low. Specific objectives were to: (1) Conduct laboratory studies of how physical and hydrologic features of the vadose zone control the spatial distribution of microbial growth and the ability of microorganisms to colonize microbially sparse or ''empty'' regions of the vadose zone. (2) Characterize microbiological properties of a carbon tetrachloride-contaminated deep vadose zone site at the DOE Hanford Site. (3) Evaluate the potential for gas phase feeding of carbon, nitrogen, and phosphorus to deep vadose zone microbial communities. (4) Use field and laboratory data generated from the project to parameterize an unsaturated zone transport model with microbial growth, colonization, and biotransformation kinetics and conduct reactive transport simulations. Pacific Northwest National Lab (PNNL) and Oregon State University (OSU) jointly addressed objectives 1, 3, and 4. PNNL addressed objective 2. For objective 4, laboratory data was simulated during the project; field data was not used in modeling and simulation due to the late initiation of the field study and the small number (n=24) of samples studied.

Download or read book Characterization of Vadose Zone Sediments Below the C Tank Farm written by Christopher F. Brown and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Impacts of Metal Contamination on Microbial Communities in Anoxic Freshwater Sediments of Lake DePue IL written by Heidi Lois Gough and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The resulting study, which included monitoring impacts of metals on microbial biomass, microbial community structure, and select population's activities, has established that anaerobic microbial communities were stressed by metal contamination and followed many trends predicted by established ecological models for stress-response. Microbial biomass concentrations decreased in negative correlation with pore water zinc and arsenic concentrations in the lake sediments. Further, an important result of this work has been the discovery of elevated biologic sulfate reduction rates in conjunction with metal contamination. While, microbial communities were similar irregardless of metal concentration, correlation was established between metal concentrations and several microbial populations. Of particular interest were data suggesting that some mesophilic crenarchaeota---a recently established sub-division of crenarchaeota kingdom may be selectively enriched in metal stressed sediments.

Download or read book Characterization of Vadose Zone Sediments Below the T Tank Farm written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report contains geologic, geochemical, and physical characterization data collected on sediment recovered from boreholes C4104 and C4105 in the T Tank Farm, and 299-W-11-39 installed northeast of the T Tank Farm. The measurements on sediments from borehole C4104 are compared to a nearby borehole 299-W10-196 placed through the plume from the 1973 T-106 tank leak. This report also presents the data in the context of sediment types, the vertical extent of contamination, the migration potential of the contaminants, and the likely source of the contamination in the vadose zone and groundwater below the T Tank Farm. Sediment samples were characterized for: moisture content, gamma-emission radionuclides, one-to-one water extracts (which provide soil pH, electrical conductivity, cation, trace metal, radionuclide and anion data), total carbon and inorganic carbon content, and 8 M nitric acid extracts (which provide a measure of the total leachable sediment content of contaminants). Overall, our analyses showed that common ion exchange is a key mechanism that influences the distribution of contaminants within that portion of the vadose zone affected by tank liquor. We observed slight elevated pH values in samples from borehole C4104. The sediments from the three boreholes, C4104, C4105, and 299-W10-196 do show that sodium-, nitrate-, and sulfate-dominated fluids are present below tank T-106 and have formed a salt plume. The fluids are more dilute than tank fluids observed below tanks at the SX and BX Tank Farms and slightly less than those from the most saline porewater found in contaminated TX tank farm sediments. The boreholes could not penetrate below the gravel-rich strata of the Ringold Formation Wooded Island member (Rwi) (refusal was met at about 130 ft bgs); therefore, we could not identify the maximum vertical penetration of the tank related plumes. The moisture content, pH, electrical conductivity, nitrate, and technetium-99 profiles versus depth in the three contaminated boreholes around T-106 do not clearly identify the leading edge of the plume. However, the profiles do collectively suggest that bulk of tank-related fluids (center of mass) still resides in Ringold Formation Taylor Flats member fine-grained sediments. Most of the chemical data, especially the nitrate and technetium-99 distributions with depth, support a flow conceptual model that suggests vertical percolation through the Hanford formation H2 unit near T-106 and then a strong horizontal spreading within the CCUu unit followed by more slow vertical percolation, perhaps via diffusion, into the deeper strata. Slow flushing by enhanced recharge and rapid snow melt events (Feb. 1979) appear to lead to more horizontal movement of the tank fluids downgradient towards C4105. The inventories as a function of depth of potential contaminants of concern, nitrate, technetium, uranium, and chromium, are provided. In-situ Kd values were calculated from water and acid extract measurements. For conservative modeling purposes we recommend using Kd values of 0 mL/g for nitrate, Co-60, and technetium-99, a value of 0.1 mL/g for uranium near borehole C4104 and 10 mL/g for U near borehole C4105, and 1 mL/g for chromium to represent the entire vadose zone profile from the bottoms of the tanks to the water table. A technetium-99 groundwater plume exists northeast and east of T WMA. The highest technetium-99 concentration in fiscal year 2003 was 9,200 pCi/L in well 299-W11-39. The most probable source for the technetium-99 is the T waste management area. Groundwater from wells in the west (upgradient) and north of WMA T appear to be highly influenced by wastes disposed to the cribs and trenches on the west side of the WMA. Groundwater from wells at the northeast corner and the east side of the WMA appears to be evolving towards tank waste that has leaked from T-101 or T-106.

Download or read book Government reports annual index written by and published by . This book was released on 199? with total page 890 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization of Vadose Zone Sediments Below the TX Tank Farm written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Pacific Northwest National Laboratory performed detailed analyses on vadose zone sediments from within Waste Management Area T-TX-TY. This report contains all the geologic, geochemical, and selected physical characterization data collected on vadose zone sediment recovered from three probe holes (C3830, C3831, and C3832) in the TX Tank Farm, and from borehole 299-W-10-27. Sediments from borehole 299-W-10-27 are considered to be uncontaminated sediments that can be compared with contaminated sediments. This report also presents our interpretation of the sediment lithologies, the vertical extent of contamination, the migration potential of the contaminants, and the likely source of the contamination in the vadose zone and groundwater below the TX Tank Farm. Sediment from the probe holes was analyzed for: moisture, radionuclide and carbon contents;, one-to-one water extracts (soil pH, electrical conductivity, cation, trace metal, and anion data), and 8 M nitric acid extracts. Overall, our analyses showed that common ion exchange is a key mechanism that influences the distribution of contaminants within that portion of the vadose zone affected by tank liquor. We did not observe significant indications of caustic alteration of the sediment mineralogy or porosity, or significant zones of slightly elevated pH values in the probe holes. The sediments do show that sodium-, nitrate-, and sulfate-dominated fluids are present. The fluids are more dilute than tank fluids observed below tanks at the SX and BX Tank Farms. Three primary stratigraphic units were encountered in each probe hole: (1) backfill material, (2) the Hanford formation, and (3) the Cold Creek unit. Each of the probe holes contain thin fine-grained layers in the Hanford H2 stratigraphic unit that may impact the flow of leaked fluids and effect irregular and horizontal flow. The probe holes could not penetrate below the enriched calcium carbonate strata of the Cold Creek lower subunit; therefore, we did not identify the maximum vertical penetration of the tank related plumes. However, the more elevated portions of the electrical conductivity (EC) profile at probe hole C3830 currently resides at the bottom of a fine-grained thin lens in the Hanford H2 unit at 87 ft bgs. At C3831, we lack good sample coverage to ascertain whether the salt plume has significantly descended into the Cold Creek Unit. There is strong indication at probe hole C3832 that the saline plume has descended into the Cold Creek Unit. The profiles do collectively suggest that the deepest penetration of tank related fluids is found in probe hole C3832. The water potential data from 299-W10-27?s H2 unit, the unit where most of the contaminants reside in the TX probe holes, are consistent with a draining profile. Despite the evidence that elevated EC values may be present in all three probe holes to their depth of refusal, the concentrations of long-term risk drivers are not large. The inventories of potential contaminants of concern, nitrate, technetium-99, uranium, and chromium, are provided. In addition, in situ desorption Kd values for these contaminants are provided. For conservative modeling purposes, we recommend using Kd values of 0 mL/g for nitrate and technetium-99, a value of 1 mL/g for uranium, and 10 mL/g for chromium to represent the entire vadose zone profile from the bottoms of the tanks to the water table. These conservative Kd values along with the provided inventories in the vadose zone sediments obtained from the three probe holes can be used in long-term risk projections that rely on estimates of water recharge and vadose zone and aquifer transport calculations.

Download or read book Monitored Natural Attenuation of Inorganic Contaminants in Ground Water written by and published by . This book was released on 2007 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: V.3 ... consists of individual chapters that describe 1) the conceptual background for radionuclides, including tritium, radon, strontium, technetium, uranium, iodine, radium, thorium, cesium, plutonium-americium and 2) data requirements to be met during site characterization.

Download or read book Chromate Effects on Microbial Activity in Vadose Zone Sediment Microcosms written by Chuck Helma and published by . This book was released on 1999 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Bioavailability of Contaminants in Soils and Sediments written by National Research Council and published by National Academies Press. This book was released on 2003-05-03 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bioavailability refers to the extent to which humans and ecological receptors are exposed to contaminants in soil or sediment. The concept of bioavailability has recently piqued the interest of the hazardous waste industry as an important consideration in deciding how much waste to clean up. The rationale is that if contaminants in soil and sediment are not bioavailable, then more contaminant mass can be left in place without creating additional risk. A new NRC report notes that the potential for the consideration of bioavailability to influence decision-making is greatest where certain chemical, environmental, and regulatory factors align. The current use of bioavailability in risk assessment and hazardous waste cleanup regulations is demystified, and acceptable tools and models for bioavailability assessment are discussed and ranked according to seven criteria. Finally, the intimate link between bioavailability and bioremediation is explored. The report concludes with suggestions for moving bioavailability forward in the regulatory arena for both soil and sediment cleanup.

Download or read book Energy Research Abstracts written by and published by . This book was released on 1993 with total page 574 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Radionuclide Behaviour in the Natural Environment written by Christophe Poinssot and published by Elsevier. This book was released on 2012-09-20 with total page 737 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding radionuclide behaviour in the natural environment is essential to the sustainable development of the nuclear industry and key to assessing potential environmental risks reliably. Minimising those risks is essential to enhancing public confidence in nuclear technology. Scientific knowledge in this field has developed greatly over the last decade.Radionuclide behaviour in the natural environment provides a comprehensive overview of the key processes and parameters affecting radionuclide mobility and migration.After an introductory chapter, part one explores radionuclide chemistry in the natural environment, including aquatic chemistry and the impact of natural organic matter and microorganisms. Part two discusses the migration and radioecological behavior of radionuclides. Topics include hydrogeology, sorption and colloidal reactions as well as in-situ investigations. Principles of modelling coupled geochemical, transport and radioecological properties are also discussed. Part three covers application issues: assessment of radionuclide behaviour in contaminated sites, taking Chernobyl as an example, estimation of radiological exposure to the population, performance assessment considerations related to deep geological repositories, and remediation concepts for contaminated sites.With its distinguished editors and international team of expert contributors, Radionuclide behaviour in the natural environment is an essential tool for all those interested or involved in nuclear energy, from researchers, designers and industrial operators to environmental scientists. It also provides a comprehensive guide for academics of all levels in this field. - Provides a comprehensive overview of the key processes and parameters affecting radionuclide mobility and migration - Explores radionuclide chemistry in the natural environment - Discusses the migration and radioecological behaviour of radionuclides