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Sample records for 300a subsurface sediments

  1. Fe(III) Reduction and U(VI) Immobilization by Paenibacillus sp. Strain 300A, Isolated from Hanford 300A Subsurface Sediments

    PubMed Central

    Ahmed, Bulbul; Cao, Bin; McLean, Jeffrey S.; Ica, Tuba; Dohnalkova, Alice; Istanbullu, Ozlem; Paksoy, Akin; Fredrickson, Jim K.

    2012-01-01

    A facultative iron-reducing [Fe(III)-reducing] Paenibacillus sp. strain was isolated from Hanford 300A subsurface sediment biofilms that was capable of reducing soluble Fe(III) complexes [Fe(III)-nitrilotriacetic acid and Fe(III)-citrate] but unable to reduce poorly crystalline ferrihydrite (Fh). However, Paenibacillus sp. 300A was capable of reducing Fh in the presence of low concentrations (2 μM) of either of the electron transfer mediators (ETMs) flavin mononucleotide (FMN) or anthraquinone-2,6-disulfonate (AQDS). Maximum initial Fh reduction rates were observed at catalytic concentrations (<10 μM) of either FMN or AQDS. Higher FMN concentrations inhibited Fh reduction, while increased AQDS concentrations did not. We also found that Paenibacillus sp. 300A could reduce Fh in the presence of natural ETMs from Hanford 300A subsurface sediments. In the absence of ETMs, Paenibacillus sp. 300A was capable of immobilizing U(VI) through both reduction and adsorption. The relative contributions of adsorption and microbial reduction to U(VI) removal from the aqueous phase were ∼7:3 in PIPES [piperazine-N,N′-bis(2-ethanesulfonic acid)] and ∼1:4 in bicarbonate buffer. Our study demonstrated that Paenibacillus sp. 300A catalyzes Fe(III) reduction and U(VI) immobilization and that these reactions benefit from externally added or naturally existing ETMs in 300A subsurface sediments. PMID:22961903

  2. Fe(III) Reduction and U(VI) Immobilization by Paenibacillus sp. Strain 300A, Isolated from Hanford 300A Subsurface Sediments

    SciTech Connect

    Ahmed, B.; Cao, B.; McLean, Jeffrey S.; Ica, Tuba; Dohnalkova, Alice; Istanbullu, Ozlem; Paksoy, Akin; Fredrickson, Jim K.; Beyenal, Haluk

    2012-11-07

    A facultative iron-reducing (Fe(III)-reducing) Paenibacillus sp. strain was isolated from Hanford 300A subsurface sediment biofilms that was capable of reducing soluble Fe(III) complexes (Fe(III)-NTA and Fe(III)-citrate) but unable to reduce poorly crystalline ferrihydrite (Fh). However, Paenibacillus sp. 300A was capable of reducing Fh in the presence of low concentrations (2 µM) of either of electron transfer mediators (ETMs) flavin mononucleotide (FMN) or anthraquinone-2,6-disulfonate (AQDS). Maximum initial Fh reduction rates were observed at catalytic concentrations (<10 µM) of either FMN or AQDS. Higher FMN concentrations inhibited Fh reduction, while increased AQDS concentrations did not. We found that Paenibacillus sp. 300A also could reduce Fh in the presence of natural ETMs from Hanford 300A subsurface sediments. In the absence of ETMs, Paenibacillus sp. 300A was capable of immobilizing U(VI) through both reduction and adsorption. The relative contributions of adsorption and microbial reduction to U(VI) removal from the aqueous phase were ~7:3 in PIPES and ~1:4 in bicarbonate buffer. Our study demonstrated that Paenibacillus sp. 300A catalyzes Fe(III) reduction and U(VI) immobilization and that these reactions benefit from externally added or naturally existing ETMs in 300A subsurface sediments.

  3. Subsurface hydrologic effects on sediment deposition

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantification of soil erosion processes has been traditionally focused on soil detachment and sediment transport while efforts in quantifying sediment deposition process are relatively minor. Nevertheless, most sediment generated on the hill slopes are deposited within the field and only a small am...

  4. Hydrogen Utilization Potential in Subsurface Sediments.

    PubMed

    Adhikari, Rishi R; Glombitza, Clemens; Nickel, Julia C; Anderson, Chloe H; Dunlea, Ann G; Spivack, Arthur J; Murray, Richard W; D'Hondt, Steven; Kallmeyer, Jens

    2016-01-01

    Subsurface microbial communities undertake many terminal electron-accepting processes, often simultaneously. Using a tritium-based assay, we measured the potential hydrogen oxidation catalyzed by hydrogenase enzymes in several subsurface sedimentary environments (Lake Van, Barents Sea, Equatorial Pacific, and Gulf of Mexico) with different predominant electron-acceptors. Hydrogenases constitute a diverse family of enzymes expressed by microorganisms that utilize molecular hydrogen as a metabolic substrate, product, or intermediate. The assay reveals the potential for utilizing molecular hydrogen and allows qualitative detection of microbial activity irrespective of the predominant electron-accepting process. Because the method only requires samples frozen immediately after recovery, the assay can be used for identifying microbial activity in subsurface ecosystems without the need to preserve live material. We measured potential hydrogen oxidation rates in all samples from multiple depths at several sites that collectively span a wide range of environmental conditions and biogeochemical zones. Potential activity normalized to total cell abundance ranges over five orders of magnitude and varies, dependent upon the predominant terminal electron acceptor. Lowest per-cell potential rates characterize the zone of nitrate reduction and highest per-cell potential rates occur in the methanogenic zone. Possible reasons for this relationship to predominant electron acceptor include (i) increasing importance of fermentation in successively deeper biogeochemical zones and (ii) adaptation of H2ases to successively higher concentrations of H2 in successively deeper zones. PMID:26858697

  5. Hydrogen Utilization Potential in Subsurface Sediments

    PubMed Central

    Adhikari, Rishi R.; Glombitza, Clemens; Nickel, Julia C.; Anderson, Chloe H.; Dunlea, Ann G.; Spivack, Arthur J.; Murray, Richard W.; D'Hondt, Steven; Kallmeyer, Jens

    2016-01-01

    Subsurface microbial communities undertake many terminal electron-accepting processes, often simultaneously. Using a tritium-based assay, we measured the potential hydrogen oxidation catalyzed by hydrogenase enzymes in several subsurface sedimentary environments (Lake Van, Barents Sea, Equatorial Pacific, and Gulf of Mexico) with different predominant electron-acceptors. Hydrogenases constitute a diverse family of enzymes expressed by microorganisms that utilize molecular hydrogen as a metabolic substrate, product, or intermediate. The assay reveals the potential for utilizing molecular hydrogen and allows qualitative detection of microbial activity irrespective of the predominant electron-accepting process. Because the method only requires samples frozen immediately after recovery, the assay can be used for identifying microbial activity in subsurface ecosystems without the need to preserve live material. We measured potential hydrogen oxidation rates in all samples from multiple depths at several sites that collectively span a wide range of environmental conditions and biogeochemical zones. Potential activity normalized to total cell abundance ranges over five orders of magnitude and varies, dependent upon the predominant terminal electron acceptor. Lowest per-cell potential rates characterize the zone of nitrate reduction and highest per-cell potential rates occur in the methanogenic zone. Possible reasons for this relationship to predominant electron acceptor include (i) increasing importance of fermentation in successively deeper biogeochemical zones and (ii) adaptation of H2ases to successively higher concentrations of H2 in successively deeper zones. PMID:26858697

  6. Plasmid incidence in bacteria from deep subsurface sediments.

    PubMed

    Fredrickson, J K; Hicks, R J; Li, S W; Brockman, F J

    1988-12-01

    Bacteria were isolated from deep terrestrial subsurface sediments underlying the coastal plain of South Carolina. A total of 163 isolates from deep sediments, surface soil, and return drill muds were examined for plasmid DNA content and resistance to the antibiotics penicillin, ampicillin, carbenicillin, streptomycin, kanamycin, and tetracycline. MICs of Cu, Cr, and Hg for each isolate were also determined. The overall frequency of plasmid occurrence in the subsurface bacteria was 33%. Resistance was most frequent to penicillin (70% of all isolates), ampicillin (49%), and carbenicillin (32%) and was concluded to be related to the concentrations of the individual antibiotics in the disks used for assaying resistance and to the production of low levels of beta-lactamase. The frequencies of resistance to penicillin and ampicillin were significantly greater for isolates bearing plasmids than for plasmidless isolates; however, resistance was not transferable to penicillin-sensitive Escherichia coli. Hybridization of subsurface bacterial plasmids and chromosomal DNA with a whole-TOL-plasmid (pWWO) probe revealed some homology of subsurface bacterial plasmid and chromosomal DNAs, indicating a potential for those bacteria to harbor catabolic genes on plasmids or chromosomes. The incidences of antibiotic resistance and MICs of metals for subsurface bacteria were significantly different from those for drill mud bacteria, ruling out the possibility that bacteria from sediments were derived from drill muds. PMID:16347789

  7. Plasmid incidence in bacteria from deep subsurface sediments

    SciTech Connect

    Fredrickson, J.K.; Hicks, R.J.; Li, S.W.; Brockman, F.J. )

    1988-12-01

    Bacteria were isolated from deep terrestrial subsurface sediments underlying the coastal plain of South Carolina. A total of 163 isolates from deep sediments, surface soil, and return drill muds were examined for plasmid DNA content and resistance to the antibiotics penicillin, ampicillin, carbenicillin, streptomycin, kanamycin, and tetracycline. MICs of Cu{sup 2+}, Cr{sup 3+}, and Hg{sup 2+} for each isolate were also determined. The overall frequency of plasmid occurrence in the subsurface bacteria was 33%. Resistance was most frequent to penicillin (70% of all isolates), ampicillin (49%), and carbenicillin (32%) and was concluded to be related to the concentrations of the individual antibiotics in the disks used for assaying resistance and to the production of low levels of {beta}-lactamase. The frequencies of resistance to penicillin and ampicillin were significantly greater for isolates bearing plasmids than for plasmidless isolates; however, resistance was not transferable to penicillin-sensitive Escherichia coli. Hybridization of subsurface bacterial plasmids and chromosomal DNA with a whole-TOL-plasmid (pWWO) probe revealed some homology of subsurface bacterial plasmid and chromosomal DNAs, indicating a potential for those bacterial to harbor catabolic genes on plasmids or chromosomes. The incidences of antibiotic resistance and MICs of metals for subsurface bacteria were significantly different from those drill mud bacteria, ruling out the possibility that bacteria from sediments were derived from drill muds.

  8. Distribution and activity of hydrogenase enzymes in subsurface sediments

    NASA Astrophysics Data System (ADS)

    Adhikari, R.; Nickel, J.; Glombitza, C.; Spivack, A. J.; D'Hondt, S. L.; Kallmeyer, J.

    2013-12-01

    Metabolically active microbial communities are present in a wide range of subsurface environments. Techniques like enumeration of microbial cells, activity measurements with radiotracer assays and the analysis of porewater constituents are currently being used to explore the subsurface biosphere, alongside with molecular biological analyses. However, many of these techniques reach their detection limits due to low microbial activity and abundance. Direct measurements of microbial turnover not just face issues of insufficient sensitivity, they only provide information about a single specific process rather than an overall microbial activity. Since hydrogenase enzymes are intracellular and ubiquitous in subsurface microbial communities, the enzyme activity represents a measure of total activity of the entire microbial community. A hydrogenase activity assay could quantify total metabolic activity without having to identify specific processes. This would be a major advantage in subsurface biosphere studies, where several metabolic processes can occur simultaneously. We quantified hydrogenase enzyme activity and distribution in sediment samples from different aquatic subsurface environments (Lake Van, Barents Sea, Equatorial Pacific and Gulf of Mexico) using a tritium-based assay. We found enzyme activity at all sites and depths. Volumetric hydrogenase activity did not show much variability between sites and sampling depths, whereas cell-specific activity ranged from 10-5 to 1 nmol H2 cell-1 d-1. Activity was lowest in sediment layers where nitrate was detected. Higher activity was associated with samples in which sulfate was the predominant electron acceptor. We found highest activity in samples from environments with >10 ppm methane in the pore water. The results show that cell-specific hydrogenase enzyme activity increases with decreasing energy yield of the electron acceptor used. It is not possible to convert volumetric or cell-specific hydrogenase activity into a

  9. Effect of Extent of Natural Subsurface Bioreduction on Fe-mineralogy of Subsurface Sediments

    SciTech Connect

    Kukkadapu, Ravi K.; Qafoku, Nikolla; Arey, Bruce W.; Resch, Charles T.; Long, Philip E.

    2010-05-16

    Naturally bioreduced zones with considerable sorbed U were recently identified at a former U mining and processing site at Rifle, CO, USA. Most of the sorbed U appears to be associated with Fe minerals. Variably reduced sediment samples were analyzed by suite of techniques, primarily by room temperature Mössbauer spectroscopy. Fe-oxides of different types and crystallinity, and Fe(II)/Fe(III)-containing clays are dominant in all the sediments. The amounts of poorly crystalline Fe(III)-oxide, however, was lower in the reduced samples. In addition, framboidal pyrites with sorbed U were common in the highly reduced sediments. Overall, the information gained from this work may help develop design field strategies for immobilization and stabilization of U(VI) in contaminated subsurface environments.

  10. Re-Defining the Subsurface Biosphere: Characterization of Fungal Populations from Energy Limited Deep Marine Subsurface Sediments

    NASA Astrophysics Data System (ADS)

    Reese, B. K.; Ariza, M.; St. Peter, C.; Hoffman, C.; Edwards, K. J.; Mills, H. J.

    2012-12-01

    The detection and characterization of metabolically active fungal populations within the deep marine subsurface will alter current ecosystem models that are limited to bacterial and archaeal populations. Although marine fungi have been studied for over fifty years, a detailed description of fungal populations within the deep subsurface is lacking. Fungi possess metabolic pathways capable of utilizing previously considered non-bioavailable energy reserves. Therefore, metabolically active fungi would occupy a unique niche within subsurface ecosystems, with the potential to provide an organic carbon source for heterotrophic prokaryotic populations not currently being considered in subsurface energy budgets. Sediments from the South Pacific Gyre subsurface, one of the most energy-limited environments on Earth, were collected during the Integrated Ocean Drilling Program (IODP) Expedition 329. Anaerobic and aerobic sediment slurry cultures using fresh sediment began directly following the completion of the Expedition (December 2010). From these cultures, multiple fungal lineages have been isolated on several media types that vary in carbon concentrations. Physical growth parameters of these subsurface fungal isolates were determined and compared to previously characterized lineages. Additionally, the overall diversity of metabolically active and dormant fungal populations was determined using high throughput sequencing of nucleic acids extracted from in situ cryopreserved South Pacific Gyre sediments. This project provides a robust step in determining the importance and impact of fungal populations within the marine subsurface biosphere.

  11. Microbial biomass and activity in subsurface sediments from Vejen, Denmark.

    PubMed

    Albrechtsen, H J; Winding, A

    1992-05-01

    Subsurface sediment samples were collected from 4 to 31 m below landsurface in glacio-fluvial sediments from the Quaternary period. The samples were described in terms of pH, electrical conductivity, chloride concentration, organic matter content, and grain size distribution. Viable counts of bacteria varied from 0.5 to 1,203 x 103 colony forming units/g dry weight (gdw); total numbers of bacteria acridine orange direct counts (AODC) varied from 1.7 to 147 × 10(7) cells/gdw; growth rates (incorporation of [(3)H]-thymidine) varied from 1.4 to 60.7 × 10(4) cells/(gdw · day); and rate constants for mineralization of (14)C-labelled compounds varied from 0.2 to 2.3 × 10(-3) ml/(dpm · day) for acetate, and from 0 to 2.0 × 10(-3) ml/(dpm · day) for phenol. Sediment texture influenced the total number of bacteria and potential for mineralization; with increasing content of clay and silt and decreasing content of sand, AODC increased and the mineralization rate declined. Intrinsic permeability calculated from grain size correlated positively with mineralization rate for acetate. Statistical correlation analysis showed high correlations between some of the abiotic parameters, but it was not possible to point out a single abiotic parameter that could explain the variation of size and activity of the microbial population. The microbial data obtained in these geologically young sediments were compared to literature data from older sediments, and this comparison showed that age and type of geological formation might be important for the size and activity of the microbial populations. PMID:24192937

  12. Biogeochemical Processes In Ethanol Stimulated Uranium Contaminated Subsurface Sediments

    SciTech Connect

    Mohanty, Santosh R.; Kollah, Bharati; Hedrick, David B.; Peacock, Aaron D.; Kukkadapu, Ravi K.; Roden, Eric E.

    2008-06-15

    A laboratory incubation experiment was conducted with uranium contaminated subsurface sediment to assess the geochemical and microbial community response to ethanol amendment. A classical sequence of TEAPs was observed in ethanol-amended slurries, with NO3- reduction, Fe(III) reduction, SO4 2- reduction, and CH4 production proceeding in sequence until all of the added 13C-ethanol (9 mM) was consumed. Approximately 60% of the U(VI) content of the sediment was reduced during the period of Fe(III) reduction. No additional U(VI) reduction took place during the sulfate-reducing and methanogenic phases of the experiment. Only gradual reduction of NO3 -, and no reduction of U(VI), took place in ethanol-free slurries. Stimulation of additional Fe(III) or SO4 2- reduction in the ethanol-amended slurries failed to promote further U(VI) reduction. Reverse transcribed 16S rRNA clone libraries revealed major increases in the abundance of organisms related to Dechloromonas, Geobacter, and Oxalobacter in the ethanolamended slurries. PLFAs indicative of Geobacter showed a distinct increase in the amended slurries, and analysis of PLFA 13C/12C ratios confirmed the incorporation of ethanol into these PLFAs. A increase in the abundance of 13C-labeled PLFAs indicative of Desulfobacter, Desulfotomaculum, and Desulfovibrio took place during the brief period of sulfate reduction which followed the Fe(III) reduction phase. Our results show that major redox processes in ethanol-amended sediments can be reliably interpreted in terms of standard conceptual models of TEAPs in sediments. However, the redox speciation of uranium is complex and cannot be explained based on simplified thermodynamic considerations.

  13. Storms as agents of wetland elevation change: their impact on surface and subsurface sediment processes

    USGS Publications Warehouse

    Cahoon, D.R.

    2003-01-01

    Direct measures of the impact of major storms on wetland sediment elevation are rare. Recently developed techniques have enabled simultaneous, quantitative observations of surface and subsurface processes affecting sediment elevation. An analysis of ten wetland sites revealed the following patterns of sediment elevation change after storm passage: (1) elevation change equivalent to sediment accretion or erosion, (2) elevation loss in spite of sediment deposition, or in excess of erosion, and (3) elevation gain greater than the amount of sediment accretion. These observations suggest that storms influence sediment elevation not only by sediment deposition and erosion but also through subsurface processes of sediment compaction, root growth and decomposition, and water flux. Wetlands receiving a substantial deposit of sediment did not always realize an equivalent elevation gain. Some realized a net loss in elevation as a result of sediment compaction apparently caused by the weight of the sediment deposit or the tidal surge waters, or both. Sediment elevation collapsed in two mangrove forests with highly organic substrate when the storm killed the forest. In two marshes, elevation gain exceeded deposition apparently through increased sediment water storage or plant root growth via nutrient enrichment from storm sediment deposits. The elevation responses were either temporary or permanent on an ecological time scale (> 8 years). In one organic marsh substrate, compaction was followed by expansion, only to be compacted again by another storm. Thus the elevation response of coastal wetlands to major storms varied depending on local substrate conditions and degree of storm impact.

  14. U(VI) Reduction in Sulfate-Reducing Subsurface Sediments Amended with Ethanol or Acetate

    PubMed Central

    Converse, Brandon J.; Wu, Tao; Findlay, Robert H.

    2013-01-01

    An experiment was conducted with subsurface sediments from Oak Ridge National Laboratory to determine the potential for reduction of U(VI) under sulfate-reducing conditions with either ethanol or acetate as the electron donor. The results showed extensive U(VI) reduction in sediments supplied with either electron donor, where geochemical and microbiological analyses demonstrated active sulfate reduction. PMID:23624470

  15. NEPTUNIUM IV AND V SORPTIN TO END-MEMBER SUBSURFACE SEDIMENTS TO THE SAVANNAH RIVER SITE

    SciTech Connect

    Kaplan, D.

    2009-11-13

    Migration of Np through the subsurface is expected to be primarily controlled by sorption to sediments. Therefore, understanding and quantifying Np sorption to sediments and sediments from the Savannah River Site (SRS) is vital to ensure safe disposal of Np bearing wastes. In this work, Np sorption to two sediments representing the geological extremes with respect to sorption properties expected in the SRS subsurface environment (named 'subsurface sandy sediment' and 'subsurface clayey sediment') was examined under a variety of conditions. First a series of baseline sorption tests at pH 5.5 under an oxic atmosphere was performed to understand Np sorption under typical subsurface conditions. These experiments indicated that the baseline K{sub d} values for the subsurface sandy and subsurface clayey sediments are 4.26 {+-} 0.24 L kg{sup -1} and 9.05 {+-} 0.61 L kg{sup -1}, respectively. These Np K{sub d} values of SRS sediments are the first to be reported since Sheppard et al. (1979). The previous values were 0.25 and 0.16 L kg{sup -1} for a low pH sandy sediment. To examine a possible range of K{sub d} values under various environmental scenarios, the effects of natural organic matter (NOM, also a surrogate for cellulose degradation products), the presence of various chemical reductants, and an anaerobic atmosphere on Np sorption were examined. The presence of NOM resulted in an increase in the Np K{sub d} values for both sediments. This behavior is hypothesized to be the result of formation of a ternary Np-NOM-sediment complex. Slight increases in the Np sorption (K{sub d} 13-24 L kg{sup -1}) were observed when performing experiments in the presence of chemical reductants (dithionite, ascorbic acid, zero-valent iron) or under anaerobic conditions. Presumably, the increased sorption can be attributed to a slight reduction of Np(V) to Np(IV), the stronger sorbing form of Np. The most significant result of this study is the finding that Np weakly sorbs to both end

  16. High virus-to-cell ratios indicate ongoing production of viruses in deep subsurface sediments.

    PubMed

    Engelhardt, Tim; Kallmeyer, Jens; Cypionka, Heribert; Engelen, Bert

    2014-07-01

    Marine sediments cover two-thirds of our planet and harbor huge numbers of living prokaryotes. Long-term survival of indigenous microorganisms within the deep subsurface is still enigmatic, as sources of organic carbon are vanishingly small. To better understand controlling factors of microbial life, we have analyzed viral abundance within a comprehensive set of globally distributed subsurface sediments. Phages were detected by electron microscopy in deep (320 m below seafloor), ancient (∼14 Ma old) and the most oligotrophic subsurface sediments of the world's oceans (South Pacific Gyre (SPG)). The numbers of viruses (10(4)-10(9) cm(-3), counted by epifluorescence microscopy) generally decreased with sediment depth, but always exceeded the total cell counts. The enormous numbers of viruses indicate their impact as a controlling factor for prokaryotic mortality in the marine deep biosphere. The virus-to-cell ratios increased in deeper and more oligotrophic layers, exhibiting values of up to 225 in the deep subsurface of the SPG. High numbers of phages might be due to absorption onto the sediment matrix and a diminished degradation by exoenzymes. However, even in the oldest sediments, microbial communities are capable of maintaining viral populations, indicating an ongoing viral production and thus, viruses provide an independent indicator for microbial life in the marine deep biosphere.

  17. High virus-to-cell ratios indicate ongoing production of viruses in deep subsurface sediments.

    PubMed

    Engelhardt, Tim; Kallmeyer, Jens; Cypionka, Heribert; Engelen, Bert

    2014-07-01

    Marine sediments cover two-thirds of our planet and harbor huge numbers of living prokaryotes. Long-term survival of indigenous microorganisms within the deep subsurface is still enigmatic, as sources of organic carbon are vanishingly small. To better understand controlling factors of microbial life, we have analyzed viral abundance within a comprehensive set of globally distributed subsurface sediments. Phages were detected by electron microscopy in deep (320 m below seafloor), ancient (∼14 Ma old) and the most oligotrophic subsurface sediments of the world's oceans (South Pacific Gyre (SPG)). The numbers of viruses (10(4)-10(9) cm(-3), counted by epifluorescence microscopy) generally decreased with sediment depth, but always exceeded the total cell counts. The enormous numbers of viruses indicate their impact as a controlling factor for prokaryotic mortality in the marine deep biosphere. The virus-to-cell ratios increased in deeper and more oligotrophic layers, exhibiting values of up to 225 in the deep subsurface of the SPG. High numbers of phages might be due to absorption onto the sediment matrix and a diminished degradation by exoenzymes. However, even in the oldest sediments, microbial communities are capable of maintaining viral populations, indicating an ongoing viral production and thus, viruses provide an independent indicator for microbial life in the marine deep biosphere. PMID:24430483

  18. Comparison of bacteria from deep subsurface sediment and adjacent groundwater.

    PubMed

    Hazen, T C; Jiménez, L; López de Victoria, G; Fliermans, C B

    1991-12-01

    Samples of groundwater and the enclosing sediments were compared for densities of bacteria using direct (acridine orange direct staining) and viable (growth on 1% PTYG medium) count methodology. Sediments to a depth of 550 m were collected from boreholes at three sites on the Savannah River Site near Aiken, South Carolina, using techniques to insure a minimum of surface contamination. Clusters of wells screened at discreet intervals were established at each site. Bacterial densities in sediment were higher, by both direct and viable count, than in groundwater samples. Differences between direct and viable counts were much greater for groundwater samples than for sediment samples. Densities of bacteria in sediment ranged from less than 1.00×10(6) bacteria/g dry weight (gdw) up to 5.01 ×10(8) bacteria/gdw for direct counts, while viable counts were less than 1.00×10(3) CFU/gdw to 4.07×10(7) CFU/gdw. Bacteria densities in groundwater were 1.00×10(3)-6.31×10(4) bacteria/ml and 5.75-4.57×10(2) CFU/ml for direct and viable counts, respectively. Isolates from sediment were also found to assimilate a wider variety of carbon compounds than groundwater bacteria. The data suggest that oligotrophic aquifer sediments have unique and dense bacterial communities that are attached and not reflected in groundwater found in the strata. Effective in situ bioremediation of contaimination in these aquifers may require sampling and characterization of sediment communities.

  19. Distribution of subsurface hydrocarbon seepage in near surface marine sediments

    SciTech Connect

    Abrams, M.A. )

    1993-02-01

    Hydrocarbon seeps in surficial marine sediments are of two types: ACTIVE: Where gas bubbles, pockmarks, or bright spots are visible on seismic records and/or the presence of chemosynthetic communities in conjunction with large concentrations of migrated-hydrocarbons. Generally in areas where generation and migration of hydrocarbons from the source rock is ongoing today (i.e., maximum burial) and/or where significant migration pathways have developed from tectonic activity. PASSIVE: Where concentrations of migrated hydrocarbons are so low that few or no geophysical anomalies are seen. Typically in areas where generation and expulsion is relict (no longer at maximum burial) and/or regional seals prevent significant vertical migration. The type of seep strongly controls the distribution of migrated hydrocarbons in the near surface sediments and should dictate the sampling equipment and approach required to detect seeps. Active seeps or macroseeps, usually can be detected near the water-sediment interface, within the water column, and at relatively large distances from major leak points. Most conventional sediment and water samplers will capture active seeps, Precise location of sampling is typically not critical to detect active seeps. The Gulf of Mexico, Santa Barbara Channel, and parts of the North Sea have active hydrocarbon seeps.

  20. Survival and phospholipid fatty acid profiles of surface and subsurface bacteria in natural sediment microcosms

    SciTech Connect

    Kieft, T.L.; Wilch, E.; O`Connor, K.

    1997-04-01

    Although starvation survival has been characterized for many bacteria, few subsurface bacteria have been tested, and few if any have been tested in natural subsurface porous media. We hypothesized that subsurface bacteria may be uniquely adapted for long-term survival in situ. We further hypothesized that subsurface conditions (sediment type and moisture content) would influence microbial survival. We compared starvation survival capabilities of surface and subsurface strains of Pseudomonas fluorescens and a novel Arthrobacter sp. in microcosms composed of natural sediments. Bacteria were incubated for up to 64 weeks under saturated and unsaturated conditions in sterilized microcosms containing either a silty sand paleosol (buried soil) or a sandy silt nonpaleosol sediment. Direct counts, plate counts, and cell sizes were measured. Membrane phospholipid fatty acid (PLFA) profiles were quantified to determine temporal patterns of PLFA stress signatures and differences in PLFAs among strains and treatments. The Arthrobacter strains survived better than the P. fluorescens strains; however, differences in survival between surface and subsurface strains of each genus were not significant. Bacteria survived better in the paleosol than in the nonpaleosol and survived better under saturated conditions than under unsaturated conditions. Cell volumes of all strains decreased; however, sediment type and moisture did not influence rates of miniaturization. Both P.fluorescens strains showed PLFA stress signatures typical for gram-negative bacteria: increased ratios of saturated to unsaturated fatty acids, increased ratios of trans- to cis-monoenoic fatty acids, and increased ratios of cyclopropyl to monoenoic precursor fatty acids. The Arthrobacter strains showed few changes in PLFAs. Environmental conditions strongly influenced PLFA profiles. 40 refs., 7 figs.

  1. Fossilization and degradation of intact polar lipids in deep subsurface sediments: A theoretical approach

    NASA Astrophysics Data System (ADS)

    Schouten, Stefan; Middelburg, Jack J.; Hopmans, Ellen C.; Sinninghe Damsté, Jaap S.

    2010-07-01

    Intact polar membrane lipids (IPLs) are frequently used as markers for living microbial cells in sedimentary environments. The assumption with these studies is that IPLs are rapidly degraded upon cell lysis and therefore IPLs present in sediments are derived from in situ microbial production. We used a theoretical approach to assess whether IPLs in surface sediments can potentially represent fossilized IPLs derived from the upper part of the water column and whether IPLs can be preserved during sediment burial. Previous studies which examined the degradation kinetics of IPLs show that phospholipids, i.e. ester-linked lipids with a phosphor-containing head group, degrade more rapidly than glycosidic ether lipids, i.e. ether-linked lipids with a glycosidically bound sugar moiety. Based on these studies, we calculate that only a minor fraction of phospholipids but a major fraction of glycosidic ether lipids biosynthesized in the upper part of the water column can potentially reach deep-sea surface sediments. Using a simple model and power law kinetic degradation parameters reported in the literature, we also evaluated the degradation of IPLs during sediment burial. Our model predicts a log-log relationship between IPL concentrations and depth, consistent with what has been observed in studies of IPLs in subsurface sediments. Although our results do not exclude production of IPLs in subsurface sediment, they do suggest that IPLs present in the deep biosphere may contain a substantial fossil component potentially masking in situ IPL production.

  2. Final report - Microbial pathways for the reduction of mercury in saturated subsurface sediments

    SciTech Connect

    Tamar barkay; Lily Young; Gerben Zylstra

    2009-08-25

    Mercury is a component of mixed wastes that have contaminated vast areas of the deep subsurface as a result of nuclear weapon and energy production. While this mercury is mostly bound to soil constituents episodes of groundwater contamination are known in some cases resulting in potable water super saturated with Hg(0). Microbial processes that reduce Hg(II) to the elemental form Hg(0) in the saturated subsurface sediments may contribute to this problem. When we started the project, only one microbial pathway for the reduction of Hg(II), the one mediated by the mer operon in mercury resistant bacteria was known. As we had previously demonstrated that the mer mediated process occurred in highly contaminated environments (Schaefer et al., 2004), and mercury concentrations in the subsurface were reported to be low (Krabbenhoft and Babiarz, 1992), we hypothesized that other microbial processes might be active in reducing Hg(II) to Hg(0) in saturated subsurface environments. The specific goals of our projects were: (1) Investigating the potential for Hg(II) reduction under varying electron accepting conditions in subsurface sediments and relating these potential to mer gene distribution; and (2) Examining the physiological and biochemical characteristics of the interactions of anaerobic bacteria with mercury. The results are briefly summarized with references to published papers and manuscripts in preparation where details about our research can be found. Additional information may be found in copies of our published manuscripts and conference proceedings, and our yearly reports that were submitted through the RIMS system.

  3. Sediment mobilization deposits from episodic subsurface fluid flow - A new tool to reveal long-term earthquake records?

    NASA Astrophysics Data System (ADS)

    Reusch, Anna; Moernaut, Jasper; Anselmetti, Flavio S.; Strasser, Michael

    2016-04-01

    Subsurface fluid flow can be affected by earthquakes: increased spring activity, mud volcano eruptions, groundwater fluctuations, changes in geyser frequency and other forms of altered subsurface fluid flow have been documented during, after, or even prior to earthquakes. Recently discovered giant pockmarks on the bottom of Lake Neuchâtel, Switzerland, are the lake-floor expression of subsurface fluid flow. They discharge karstic groundwater from the Jura Mountains and experience episodically increased subsurface fluid flow documented by subsurface sediment mobilization deposits at the levees of the pockmarks. In this study, we present the spatio-temporal distribution of event deposits from phases of sediment expulsion and their time correlative multiple mass-transport deposits. We report striking evidence for five events of concurrent multiple subsurface sediment deposits and multiple mass-transport deposits since Late Glacial times, for which we propose past earthquakes as trigger. Comparison of this new event catalogue with historic earthquakes and other independent paleoseismic records suggests that initiation of sediment expulsion requires a minimum macroseismic intensity of VII. Thus, our study presents for the first time sedimentary deposits resulting from increased subsurface fluid flow as new paleoseismic proxy. Comparable processes must also be relevant for other mountain front ranges and coastal mountain ranges, where groundwater flow triggers subsurface sediment mobilization and discharges into lacustrine and marine settings.

  4. Biosphere frontiers of subsurface life in the sedimented hydrothermal system of Guaymas Basin.

    PubMed

    Teske, Andreas; Callaghan, Amy V; LaRowe, Douglas E

    2014-01-01

    Temperature is one of the key constraints on the spatial extent, physiological and phylogenetic diversity, and biogeochemical function of subsurface life. A model system to explore these interrelationships should offer a suitable range of geochemical regimes, carbon substrates and temperature gradients under which microbial life can generate energy and sustain itself. In this theory and hypothesis article, we make the case for the hydrothermally heated sediments of Guaymas Basin in the Gulf of California as a suitable model system where extensive temperature and geochemical gradients create distinct niches for active microbial populations in the hydrothermally influenced sedimentary subsurface that in turn intercept and process hydrothermally generated carbon sources. We synthesize the evidence for high-temperature microbial methane cycling and sulfate reduction at Guaymas Basin - with an eye on sulfate-dependent oxidation of abundant alkanes - and demonstrate the energetic feasibility of these latter types of deep subsurface life in previously drilled Guaymas Basin locations of Deep-Sea Drilling Project 64.

  5. Radioiodine sorption/desorption and speciation transformation by subsurface sediments from the Hanford Site

    SciTech Connect

    Xu, Chen; Kaplan, Daniel I.; Zhang, Saijin; Athon, Matthew; Ho, Yi-Fang; Li, Hsiu-Ping; Yeager, Chris; Schwehr, Kathy; Grandbois, Russell; Wellman, Dawn M.; Santschi, Peter H.

    2015-01-01

    During the last few decades, considerable research efforts have been extended to identify more effective remediation treatment technologies to lower the 129I concentrations to below federal drinking water standards at the Hanford Site (Richland, USA). Few studies have taken iodate into consideration, though recently iodate, instead of iodide, was identified as the major species in the groundwater of 200-West Area within the Hanford Site. The objective of this study was thus to quantify and understand aqueous radioiodine species transformations and uptake by three sediments collected from the semiarid, carbonate-rich environment of the Hanford subsurface. All three sediments reduced iodate (IO-) to iodide (I-), but the loamy-sand sediment reduced more IO3- (100% reduced within 7 days) than the two sand-textured sediments (~20% reduced after 28 days). No dissolved organo-iodine species were observed in any of these studies.

  6. Methane production from protozoan endosymbionts following stimulation of microbial metabolism within subsurface sediments

    PubMed Central

    Holmes, Dawn E.; Giloteaux, Ludovic; Orellana, Roberto; Williams, Kenneth H.; Robbins, Mark J.; Lovley, Derek R.

    2014-01-01

    Previous studies have suggested that protozoa prey on Fe(III)- and sulfate-reducing bacteria that are enriched when acetate is added to uranium contaminated subsurface sediments to stimulate U(VI) reduction. In order to determine whether protozoa continue to impact subsurface biogeochemistry after these acetate amendments have stopped, 18S rRNA and ß-tubulin sequences from this phase of an in situ uranium bioremediation field experiment were analyzed. Sequences most similar to Metopus species predominated, with the majority of sequences most closely related to M. palaeformis, a cilitated protozoan known to harbor methanogenic symbionts. Quantification of mcrA mRNA transcripts in the groundwater suggested that methanogens closely related to Metopus endosymbionts were metabolically active at this time. There was a strong correlation between the number of mcrA transcripts from the putative endosymbiotic methanogen and Metopus ß-tubulin mRNA transcripts during the course of the field experiment, suggesting that the activity of the methanogens was dependent upon the activity of the Metopus species. Addition of the eukaryotic inhibitors cyclohexamide and colchicine to laboratory incubations of acetate-amended subsurface sediments significantly inhibited methane production and there was a direct correlation between methane concentration and Metopus ß-tubulin and putative symbiont mcrA gene copies. These results suggest that, following the stimulation of subsurface microbial growth with acetate, protozoa harboring methanogenic endosymbionts become important members of the microbial community, feeding on moribund biomass and producing methane. PMID:25147543

  7. Microbial Reductive Transformation of Phyllosilicate Fe(III) and U(VI) in Fluvial Subsurface Sediments

    SciTech Connect

    Lee, Ji-Hoon; Fredrickson, Jim K.; Kukkadapu, Ravi K.; Boyanov, Maxim I.; Kemner, Kenneth M.; Lin, Xueju; Kennedy, David W.; Bjornstad, Bruce N.; Konopka, Allan; Moore, Dean A.; Resch, Charles T.; Phillips, Jerry L.

    2012-03-14

    The microbial reduction of Fe(III) and U(VI) were investigated in shallow aquifer sediments collected from subsurface Pleistocene flood deposits near the Hanford Reach of the Columbia River in Washington State. Increases in 0.5 N HCl-extractable Fe(II) were observed in incubated sediments and 57Fe Mössbauer spectroscopy revealed that Fe(III) associated with phyllosilicates and pyroxene was reduced to Fe(II). Aqueous uranium(VI) concentrations decreased in incubated Hanford sediments with the rate and extent being greater in sediment amended with organic carbon. X-ray absorption spectroscopy of bioreduced sediments indicated that 67-77% of the U signal was U(VI), probably as an adsorbed species associated with a new or modified reactive mineral phase. Phylotypes within the Deltaproteobacteria were more common in Hanford sediments incubated with U(VI) than without and in U(VI)-free incubations, members of the Clostridiales were dominant with sulfate-reducing phylotypes more common in the sulfate-amended sediments. These results demonstrate the potential for anaerobic reduction phyllosilicate Fe(III) and sulfate in Hanford unconfined aquifer sediments and biotransformations involving reduction and adsorption leading to decreased aqueous U concentrations.

  8. Biogeography and diversity of methane and sulfur-cycling ecotypes in deep subsurface sediments

    NASA Astrophysics Data System (ADS)

    Adams, M. M.; Biddle, J.; Girguis, P. R.

    2013-12-01

    The microbially mediated anaerobic oxidation of methane (AOM) is critical for regulating the flux of methane from the ocean. AOM is coupled to sulfate availability in many anoxic marine environments, which has been extensively studied at cold seeps, hydrothermal vents, and the sulfate-methane transition zone at the seafloor. The microbes known to catalyze AOM form phylogenetically distinct anaerobic methanotroph (ANME) clusters and sometimes live in concert with sulfate-reducing bacteria (SRB). Strikingly, certain ANME groups and subgroups have been shown to occupy different ecological niches in both hydrocarbon seep and hydrothermal vent sediments. However, the environmental parameters that select for certain phylogenetic variants or 'ecotypes' in a wide range of marine systems are still unknown. A marine environment that remains elusive to characterization of potential ANME and SRB ecotype diversity is methane hydrate formations in the deep subsurface. Current estimates indicate that seafloor hydrates may exceed 10,000 GtC at standard temperature and pressure conditions. However, only a handful of studies have investigated the potential for AOM in the deep subsurface associated with methane hydrates. To gain a better understanding of the distribution of methane- and sulfur- cycling ecotypes in biogeochemically distinct marine subsurface ecosystems, we generated a substantial library of 16S rRNA gene sequences for these uncultivable deep sea microorganisms using Illumina sequencing. Sediment strata were collected from the methane-hydrate associated deep subsurface of Hydrate Ridge (30 - 100 mbsf), hydrocarbon cold seeps of Monterey Bay, metalliferous sedimented hydrothermal vents of Juan de Fuca Ridge, and organic-rich hydrothermally influenced sediments of Guaymas Basin. We used the Illumina MiSeq sequencing platform to assess Archaeal and Bacterial richness in a total of 36 deep sea sediment samples followed by qPCR for quantification of ANME and SRB phylotype

  9. Don Quixote Pond Sediments: Surface and Subsurface Chemistry and Mineralogy

    NASA Astrophysics Data System (ADS)

    Englert, P. A. J.; Bishop, J. L.; Patel, S.; Gibson, E. K.; Koeberl, C.

    2014-12-01

    Don Quixote Pond, like Don Juan Pond in the South Fork of Wright Valley, Antarctica, is a model for calcium and chlorine weathering and distribution on Mars. It is located in the western part of the North Fork about 100 m above Mean Seawater Level; its brine is seasonally frozen [1]. Field observations show zones of discoloration which grow lighter with distance from the pond edges. Four sediment cores, a set of radial surface samples, special surface samples, and samples of local rocks were obtained [2]. We report on chemical and mineral analyses of traverse samples and on two cores. Core DQ20 is a northeastern shoreline core. Its soluble salt concentration exceeds 200 micromoles/g in the top 5 cm, and then falls to less than 70 micromoles/g at the permafrost depth of 15 cm. These concentrations are low when compared to similarly positioned locations at Don Juan Pond and to cores from Prospect Mesa close to Lake Vanda, Wright Valley. Halite, soda niter, tachyhydrite and/bischovite are suggested from the ionic molar relationships Measured halite concentrations of surface samples, collected along a traverse of 35 m from the pond outwards, range from over 5% to trace amounts, decreasing with distance. Gypsum is also present in almost all of these samples ranging from 0.2% to 2.6%, but does not exhibit a trend. However, in core DQ35, located at a distance of 15 m along the traverse, gypsum decreases from 2.5% to 0.6% from the surface to the permafrost depth of 12 cm. While DQ35 and radial samples show high quartz and albite abundance, samples that contained visible encrustations and evaporites are low in these minerals and rich in highly diverse alteration products. Don Juan Basin ponds may have formed by a complex surface water mobilization of weathering products [3] and local groundwater action [4,5]. In contrast, Don Quixote pond mineralogy and chemistry may be consistent with a less complex shallow and deep groundwater system origin [1]. [1] Harris H

  10. Sorption and oxic degradation of the explosive CL-20 during transport in subsurface sediments.

    PubMed

    Szecsody, J E; Girvin, D C; Devary, B J; Campbell, J A

    2004-08-01

    The abiotic sorption and oxic degradation processes that control the fate of the explosive CL-20, Hexanitrohexaazaisowurtzitane, in the subsurface environment were investigated to determine the potential for vadose and groundwater contamination. Sorption of aqueous CL-20 is relatively small (K(d) = 0.02-3.83 cm3 g(-1) for 7 sediments and 12 minerals), which results in only slight retardation relative to water movement. Thus, CL-20 could move quickly through unsaturated and saturated sediments of comparable composition to groundwater, similar to the subsurface behavior of RDX. CL-20 sorption was mainly to mineral surfaces of the sediments, and the resulting isotherm was nonlinear. CL-20 abiotically degrades in oxic environments at slow rates (i.e., 10s to 100s of hours) with a wide variety of minerals, but at fast rates (i.e., minutes) in the presence of 2:1 phyllosilicate clays (hectorite, montmorillonite, nontronite), micas (biotite, illite), and specific oxides (MnO2 and the ferrous-ferric iron oxide magnetite). High concentrations of surface ferrous iron in a dithionite reduced sediment degraded CL-20 the fastest (half-life < 0.05 h), but 2:1 clays containing no structural or adsorbed ferrous iron (hectorite) could also quickly degrade CL-20 (half-life < 0.2 h). CL-20 degradation rates were slower in natural sediments (half-life 3-800 h) compared to minerals. Sediments with slow degradation rates and small sorption would exhibit the highest potential for deep subsurface migration. Products of CL-20 oxic degradation included three high molecular weight compounds and anions (nitrite and formate). The 2-3.5 moles of nitrite produced suggest CL-20 nitro-groups are degraded, and the amount of formate produced (0.2-1.2 moles) suggests the CL-20 cage structure is broken in some sediments. Identification of further degradation products and CL-20 mineralization rates is needed to fully assess the impact of these CL-20 transformation rates on the risk of CL-20 (and

  11. Sorption and oxic degradation of the explosive CL-20 during transport in subsurface sediments.

    PubMed

    Szecsody, J E; Girvin, D C; Devary, B J; Campbell, J A

    2004-08-01

    The abiotic sorption and oxic degradation processes that control the fate of the explosive CL-20, Hexanitrohexaazaisowurtzitane, in the subsurface environment were investigated to determine the potential for vadose and groundwater contamination. Sorption of aqueous CL-20 is relatively small (K(d) = 0.02-3.83 cm3 g(-1) for 7 sediments and 12 minerals), which results in only slight retardation relative to water movement. Thus, CL-20 could move quickly through unsaturated and saturated sediments of comparable composition to groundwater, similar to the subsurface behavior of RDX. CL-20 sorption was mainly to mineral surfaces of the sediments, and the resulting isotherm was nonlinear. CL-20 abiotically degrades in oxic environments at slow rates (i.e., 10s to 100s of hours) with a wide variety of minerals, but at fast rates (i.e., minutes) in the presence of 2:1 phyllosilicate clays (hectorite, montmorillonite, nontronite), micas (biotite, illite), and specific oxides (MnO2 and the ferrous-ferric iron oxide magnetite). High concentrations of surface ferrous iron in a dithionite reduced sediment degraded CL-20 the fastest (half-life < 0.05 h), but 2:1 clays containing no structural or adsorbed ferrous iron (hectorite) could also quickly degrade CL-20 (half-life < 0.2 h). CL-20 degradation rates were slower in natural sediments (half-life 3-800 h) compared to minerals. Sediments with slow degradation rates and small sorption would exhibit the highest potential for deep subsurface migration. Products of CL-20 oxic degradation included three high molecular weight compounds and anions (nitrite and formate). The 2-3.5 moles of nitrite produced suggest CL-20 nitro-groups are degraded, and the amount of formate produced (0.2-1.2 moles) suggests the CL-20 cage structure is broken in some sediments. Identification of further degradation products and CL-20 mineralization rates is needed to fully assess the impact of these CL-20 transformation rates on the risk of CL-20 (and

  12. Immobilization and Natural Attenuation of Arsenic in Surface and Subsurface Sediments

    NASA Astrophysics Data System (ADS)

    O'Day, P. A.; Illera, V.; Choi, S.; Vlassopoulos, D.

    2008-12-01

    Understanding of molecular-scale biogeochemical processes that control the mobilization and distribution of As and other oxyanions can be used to develop remediation strategies that take advantage of natural geochemical and hydrologic gradients. Arsenic and other toxic oxyanions can be mobilized at low bulk sediment concentrations (ppm range) and thus, treatment technologies are challenged by low contaminant concentrations, widespread sources, variable pH and Eh conditions, and inaccessibility of subsurface environments. In situ chemical amendments to soils and sediments can be used to decrease the mobility and bioaccessibility of As and oxyanions through sorption to, or precipitation with, stabilizing phases. At a site near San Francisco Bay (CA, USA), treatment of As-contaminated soils with sulfate-cement amendments has effectively immobilized As. Laboratory experiments with field soils and spectroscopic characterizations showed that in high pH cement-type treatments, As is precipitated in ettringite-type phases (Ca-Al sulfates), whereas in low pH ferrous sulfate treatments, As is associated with an iron-arsenate phase (angellelite). The presence of As-associated ettringite-type phases in field sediments amended more than a decade ago indicates long-term stability of these neophases, as long as environmental conditions are relatively constant. At sites of subsurface contamination, monitored natural attenuation (MNA) as a remediation approach for As is gaining interest and acceptance. Successful implementation of MNA requires a mechanistic understanding of As sequestration processes and of the subsurface conditions that may enhance or reduce long-term effectiveness. At a former military site (MA, USA), naturally occurring As was mobilized from sediments as a result of reducing conditions from addition of organic carbon as a biodegradation treatment of chlorinated solvents. Elevated As concentrations were not detected further than about 30 m downgradient of the

  13. Microbially catalyzed nitrate-dependent metal/radionuclide oxidation in shallow subsurface sediments

    NASA Astrophysics Data System (ADS)

    Weber, K.; Healy, O.; Spanbauer, T. L.; Snow, D. D.

    2011-12-01

    Anaerobic, microbially catalyzed nitrate-dependent metal/radionuclide oxidation has been demonstrated in a variety of sediments, soils, and groundwater. To date, studies evaluating U bio-oxidation and mobilization have primarily focused on anthropogenically U contaminated sites. In the Platte River Basin U originating from weathering of uranium-rich igneous rocks in the Rocky Mountains was deposited in shallow alluvial sediments as insoluble reduced uranium minerals. These reduced U minerals are subject to reoxidation by available oxidants, such nitrate, in situ. Soluble uranium (U) from natural sources is a recognized contaminant in public water supplies throughout the state of Nebraska and Colorado. Here we evaluate the potential of anaerobic, nitrate-dependent microbially catalyzed metal/radionuclide oxidation in subsurface sediments near Alda, NE. Subsurface sediments and groundwater (20-64ft.) were collected from a shallow aquifer containing nitrate (from fertilizer) and natural iron and uranium. The reduction potential revealed a reduced environment and was confirmed by the presence of Fe(II) and U(IV) in sediments. Although sediments were reduced, nitrate persisted in the groundwater. Nitrate concentrations decreased, 38 mg/L to 30 mg/L, with increasing concentrations of Fe(II) and U(IV). Dissolved U, primarily as U(VI), increased with depth, 30.3 μg/L to 302 μg/L. Analysis of sequentially extracted U(VI) and U(IV) revealed that virtually all U in sediments existed as U(IV). The presence of U(IV) is consistent with reduced Fe (Fe(II)) and low reduction potential. The increase in aqueous U concentrations with depth suggests active U cycling may occur at this site. Tetravalent U (U(IV)) phases are stable in reduced environments, however the input of an oxidant such as oxygen or nitrate into these systems would result in oxidation. Thus co-occurrence of nitrate suggests that nitrate could be used by bacteria as a U(IV) oxidant. Most probable number

  14. Sorption and Oxic Degradation of the Explosive CL-20 During Transport in Subsurface Sediments

    SciTech Connect

    Szecsody, Jim E.; Girvin, Donald C.; Devary, Brooks J.; Campbell, James A.

    2004-08-15

    The abiotic sorption and oxic degradation processes that control the fate of the explosive CL-20, Hexanitrohexaazaisowurtzitane, in the subsurface environment were investigated to determine the potential for vadose and groundwater contamination. Sorption of CL-20 is relatively small (Kd = 0.02 to 4.2 cm3 g-1, 7 low organic carbon sediments, 12 minerals), which results in only slight retardation relative to water, so CL-20 could move quickly through unsaturated and saturated sediments to groundwater. Sorption was mainly to mineral surfaces for these low organic carbon sediments, and the resulting isotherm was nonlinear. CL-20 abiotically degrades in an oxic environment at slow rates (i.e., 10s to 100s of hours) with a wide variety of minerals, but at fast rates (i.e., minutes) in the presence of 2:1 clays (biotite, hectorite, montmorillonite, illite), ferrous iron oxides (i.e., magnetite) and manganous oxide. High concentrations of surface ferrous iron degraded CL-20 the fastest, but 2:1 clays containing no structural or adsorbed ferrous iron (hectorite) could also quickly degrade CL-20. Products of CL-20 oxic degradation included three high molecular weight compounds and anions (nitrite and formate). The 2 to 3.5 moles of nitrite produced suggests the CL-20 cage remains intact. Identification of further degradation products and CL-20 mineralization rates is needed to fully assess the impact of these CL-20 transformation rates on the risk of CL-20 (and degradation product) subsurface movement.

  15. Subsurface sediment mobilization and active pockmarks from sublacustrine ground-water seepage

    NASA Astrophysics Data System (ADS)

    Reusch, A.; Moernaut, J.; Loher, M.; Hilbe, M.; Meinecke, G.; Kipfer, R.; Anselmetti, F.; Bouffard, D.; Strasser, M.

    2014-12-01

    Lakes can be used as "model basins" to study fluid-flow processes with a multi-method approach in a well-defined environment. We present unprecedented insight into newly discovered pockmarks and associated subsurface sediment-mobilization structures in Lake Neuchâtel, Switzerland. A geophysical approach using multiple tools provides precise high-resolution bathymetric data and subsurface information of the sedimentary infill. We combine geophysical (300 kHz Kongsberg EM2040 multibeam, 3.5 kHz pinger seismic, deep-towed multi-frequency chirp seismic, mounted on an AUV), sedimentological (piston cores), hydrological (CTD), geochemical (methane, δ18O) and visual (ROV survey) data and observations. The data show several circular, crater-shaped pockmarks of up to 160 m in diameter and up to 30 m depth. The pockmarks are partially filled with mud in a fluid-like state. It is hypothesized that this mud is a result of active fluid flow within the pockmark. The levees of the pockmarks are characterized by high-amplitude wedge-shaped seismic reflections being intercalated with the background sediments. They are interpreted as overflow deposits originating from episodic increases in fluid flow from inside the pockmarks, causing sediment to be spilled over the margin and deposited on the levees. Data show multiple phases of sediment expulsion during discrete periods throughout the Holocene. Geochemical sediment analyses of headspace methane indicate the presence of purely microbial methane at low concentrations, thus no indications of active gas seepage. Elevated temperature values and depleted δ18O signals within the pockmark, compared to the reference sites, hint towards different water sources. We interpret these data to show two water bodies: (i) lake bottom-water, and (ii) groundwater entering as focused fluid flow through the pockmark. This multi-proxy approach shows that the newly discovered pockmarks of Lake Neuchâtel are sublacustrine springs, possibly related to

  16. Marine Subsurface Microbial Communities Across a Hydrothermal Gradient in Okinawa Trough Sediments

    NASA Astrophysics Data System (ADS)

    Brandt, L. D.; Hser Wah Saw, J.; Ettema, T.; House, C. H.

    2015-12-01

    IODP Expedition 331 to the Okinawa backarc basin provided an opportunity to study the microbial stratigraphy within the sediments surrounding a hydrothermal vent. The Okinawa backarc basin is a sedimented region of the seafloor located on a continental margin, and also hosts a hydrothermal network within the subsurface. Site C0014 within the Iheya North hydrothermal field is located 450 m east of the active vent and has a surface temperature of 5°C with no evidence of hydrothermal alteration within the top 10 meters below sea floor (mbsf). Temperature increases with depth at an estimated rate of 3°C/m and transitions from non-hydrothermal margin sediments to a hydrothermally altered regime below 10 mbsf. In this study, we utilized deep 16S rRNA sequencing of DNA from IODP Expedition 331 Site C0014 sediment horizons in order to assess diversity throughout the sediment column as well as determine the potential limits of the biosphere. Analysis of the amplicon data shows a shift over 15 mbsf from a heterogeneous community of cosmopolitan marine subsurface taxa toward an archaeal-dominated community in the deepest horizons of the predicted biosphere. Notably, the phylum Chloroflexi represents a substantial taxon through most horizons, where it appears to be replaced below 10 mbsf by punctuations of thermophilic and methanotrophic Archaea and Miscellaneous Crenarchaeotic Group abundances. DNA from the aforementioned transition horizons was further analyzed using metagenomic sequencing. Preliminary taxonomic analysis of the metagenomic data agrees well with amplicon data in capturing the shift in relative abundance of Archaea increasing with depth. Additionally, reverse gyrase, a gene found exclusively in hyperthermophilic microorganisms, was recovered only in the metagenome of the deepest horizon. A BLAST search of this protein sequence against the GenBank non-redudnant protein database produced top hits with reverse gyrase from Thermococcus and Pyrococcus, which are

  17. The microbial methane cycle in subsurface sediments. Final project report, July 1, 1993--August 31, 1997

    SciTech Connect

    Grossman, E.L.; Ammerman, J.W.; Suflita, J.M.

    1997-12-31

    The objectives of this study were to determine the factors controlling microbial activity and survival in the subsurface and, specifically, to determine whether microbial communities in aquitards and in aquifer microenvironments provide electron donors and/or acceptors that enhance microbial survival in aquifers. Although the original objectives were to focus on methane cycling, the authors pursued an opportunity to study sulfur cycling in aquifer systems, a process of much greater importance in microbial activity and survival, and in the mobility of metals in the subsurface. Furthermore, sulfur cycling is pertinent to the Subsurface Science Program`s study at Cerro Negro, New Mexico. The study combined field and laboratory approaches and microbiological, molecular, geochemical, and hydrogeological techniques. During drilling operations, sediments were collected aseptically and assayed for a variety of microorganisms and metabolic capabilities including total counts, viable aerobic heterotrophs, total anaerobic heterotrophs, sulfate reducing bacteria (SRB) and sulfate reduction activity (in situ and in slurries), methanogens, methanotrophs, and Fe- and S-oxidizers, among others. Geochemical analyses of sediments included organic carbon content and {sup 13}C/{sup 12}C ratio, sulfur chemistry (reduced sulfur, sulfate), {sup 34}S/{sup 32}S, {sup 13}C/{sup 12}C, {sup 14}C, tritium, etc. The authors drilled eight boreholes in the Eocene Yegua formation at four localities on the Texas A&M University campus using a hollow-stem auger drilling rig. The drilling pattern forms a T, with three well clusters along the dip direction and two along strike. Four boreholes were sampled for sediments and screened at the deepest sand interval encountered, and four boreholes were drilled to install wells in shallower sands. Boreholes range in depth from 8 to 31 m, with screened intervals ranging from 6 to 31 m. Below are the results of these field studies.

  18. A new DNA extraction method by controlled alkaline treatments from consolidated subsurface sediments.

    PubMed

    Kouduka, Mariko; Suko, Takeshi; Morono, Yuki; Inagaki, Fumio; Ito, Kazumasa; Suzuki, Yohey

    2012-01-01

    Microbial communities that thrive in subterranean consolidated sediments are largely unknown owing to the difficulty of extracting DNA. As this difficulty is often attributed to DNA binding onto the silica-bearing sediment matrix, we developed a DNA extraction method for consolidated sediment from the deep subsurface in which silica minerals were dissolved by being heated under alkaline conditions. NaOH concentrations (0.07 and 0.33 N), incubation temperatures (65 and 94 °C) and incubation times (30-90 min) before neutralization were evaluated based on the copy number of extracted prokaryotic DNA. Prokaryotic DNA was detected by quantitative PCR analysis after heating the sediment sample at 94 °C in 0.33 N NaOH solution for 50-80 min. Results of 16S rRNA gene sequence analysis of the extracted DNA were all consistent with regard to the dominant occurrence of the metallophilic bacterium, Cupriavidus metallidurans, and Pseudomonas spp. Mineralogical analysis revealed that the dissolution of a silica mineral (opal-CT) during alkaline treatment was maximized at 94 °C in 0.33 N NaOH solution for 50 min, which may have resulted in the release of DNA into solution. Because the optimized protocol for DNA extraction is applicable to subterranean consolidated sediments from a different locality, the method developed here has the potential to expand our understanding of the microbial community structure of the deep biosphere.

  19. Subsurface sediment contamination during borehole drilling with an air-actuated down-hole hammer.

    PubMed

    Malard, Florian; Datry, Thibault; Gibert, Janine

    2005-10-01

    Drilling methods can severely alter physical, chemical, and biological properties of aquifers, thereby influencing the reliability of water samples collected from groundwater monitoring wells. Because of their fast drilling rate, air-actuated hammers are increasingly used for the installation of groundwater monitoring wells in unconsolidated sediments. However, oil entrained in the air stream to lubricate the hammer-actuating device can contaminate subsurface sediments. Concentrations of total hydrocarbons, heavy metals (Cu, Ni, Cr, Zn, Pb, and Cd), and nutrients (particulate organic carbon, nitrogen, and phosphorus) were measured in continuous sediment cores recovered during the completion of a 26-m deep borehole drilled with a down-hole hammer in glaciofluvial deposits. Total hydrocarbons, Cu, Ni, Cr and particulate organic carbon (POC) were all measured at concentrations far exceeding background levels in most sediment cores. Hydrocarbon concentration averaged 124 +/- 118 mg kg(-1) dry sediment (n = 78 samples) with peaks at depths of 8, 14, and 20 m below the soil surface (maximum concentration: 606 mg kg(-1)). The concentrations of hydrocarbons, Cu, Ni, Cr, and POC were positively correlated and exhibited a highly irregular vertical pattern, that probably reflected variations in air loss within glaciofluvial deposits during drilling. Because the penetration of contaminated air into the formation is unpreventable, the representativeness of groundwater samples collected may be questioned. It is concluded that air percussion drilling has strong limitations for well installation in groundwater quality monitoring surveys.

  20. Characterization of anaerobic chloroethene-dehalogenating activity in several subsurface sediments

    SciTech Connect

    Skeen, R.S.; Gao, J.; Hooker, B.S.; Quesenberry, R.D.

    1996-11-01

    Anaerobic microcosms of subsurface soils from four locations were used to investigate the separate effects of several electron donors on tetrachloroethylene (PCE) dechlorination activity. The substrates tested were methanol, formate, lactate, acetate, and sucrose. Various levels of sulfate-reducing, acetogenic, fermentative, and methanogenic activity were observed in all sediments. PCE dechlorination was detected in all microcosms, but the amount of dehalogenation varied by several orders of magnitude. Trichloroethylene was the primary dehalogenation product; however, small amounts of cis-1,2-dichloroethylene, 1,1-dichloroethylene, and vinyl chloride were also detected in several microcosms. Lactate-amended microcosms showed large amounts of dehalogenation. in three of the four sediments. One of the two sediments which showed positive activity with lactate also had large amounts of delialogenation with methanol. Sucrose, formate, and acetate also stimulated large amounts of delialogenation in one sediment that showed activity with lactate. These results suggest that lactate may be an appropriate substrate for screening sediments for PCE or TCE delialogenation activity, but that the microbial response is not sufficient for complete in situ bioremediation. A detailed study of the Victoria activity revealed that delialogenation rates were more similar to the Cornell culture than to rates measured for methanogens, or a methanol-enriched sediment culture. This may suggest that these sediments contain a highly efficient delialogenation activity similar to the Cornell culture. This assertion is supported further by the fact that an average of 3% of added reducing equivalents could be diverted to dehalogenation in tests which were conducted using PCE-saturated hexadecane as a constant source of PCE during incubation. Further evidence is needed to confirm this premise. The application of these results to in situ bioremediation of highly contaminated areas are discussed.

  1. Quantifying microbial activity in deep subsurface sediments using a tritium based hydrognease enzyme assay

    NASA Astrophysics Data System (ADS)

    Adhikari, R.; Nickel, J.; Kallmeyer, J.

    2012-12-01

    Microbial life is widespread in Earth's subsurface and estimated to represent a significant fraction of Earth's total living biomass. However, very little is known about subsurface microbial activity and its fundamental role in biogeochemical cycles of carbon and other biologically important elements. Hydrogen is one of the most important elements in subsurface anaerobic microbial metabolism. Heterotrophic and chemoautotrophic microorganisms use hydrogen in their metabolic pathways. They either consume or produce protons for ATP synthesis. Hydrogenase (H2ase) is a ubiquitous intracellular enzyme that catalyzes the interconversion of molecular hydrogen and/or water into protons and electrons. The protons are used for the synthesis of ATP, thereby coupling energy generating metabolic processes to electron acceptors such as CO2 or sulfate. H2ase enzyme targets a key metabolic compound in cellular metabolism therefore the assay can be used as a measure for total microbial activity without the need to identify any specific metabolic process. Using the highly sensitive tritium assay we measured H2ase enzyme activity in the organic-rich sediments of Lake Van, a saline, alkaline lake in eastern Turkey, in marine sediments of the Barents Sea and in deep subseafloor sediments from the Nankai Trough. H2ase activity could be quantified at all depths of all sites but the activity distribution varied widely with depth and between sites. At the Lake Van sites H2ase activity ranged from ca. 20 mmol H2 cm-3d-1 close to the sediment-water interface to 0.5 mmol H2 cm-3d-1 at a depth of 0.8 m. In samples from the Barents Sea H2ase activity ranged between 0.1 to 2.5 mmol H2 cm-3d-1 down to a depth of 1.60 m. At all sites the sulfate reduction rate profile followed the upper part of the H2ase activity profile until sulfate reduction reached the minimum detection limit (ca. 10 pmol cm-3d-1). H2ase activity could still be quantified after the decline of sulfate reduction, indicating that

  2. Protozoa in subsurface sediments from sites contaminated with aviation gasoline or jet fuel

    SciTech Connect

    Sinclair, J.L.; Kampbell, D.H.; Cook, M.L.; Wilson, J.T. )

    1993-02-01

    Fuel hydrocarbons are known to be readily biodegraded and protozoa may be associated with this process. The objective of this study is to determine whether protozoa are numerous enough in the contaminated areas of the subsurface to play a significant role in the microbial community. The results indicate that protozoa can become very numerous in the subsurface at fuel-contaminated sites with the greatest abundance of protozoa in the unsaturated zone, where fuel vapors mixed with atmospheric oxygen, and slightly beneath the floating fuel on the water table. In contrast, bacteria seemed to adapt to local conditions and showed less change in numbers in different parts of the profile than protozoa. Bioremediation of subsurface sediments is dependent on a sufficient hydraulic conductivity to permit pumping nutrients through the affected area. Bacteria have been known to cause large reductions in hydraulic conductivity. At the study area this reduction was not noted in spite of large concentrations of bacteria. The authors conclude that this may indicate a role for protozoa in maintaining hydraulic conductivity during biotreatment of readily degraded organic contaminants.

  3. Biosphere frontiers of subsurface life in the sedimented hydrothermal system of Guaymas Basin

    PubMed Central

    Teske, Andreas; Callaghan, Amy V.; LaRowe, Douglas E.

    2014-01-01

    Temperature is one of the key constraints on the spatial extent, physiological and phylogenetic diversity, and biogeochemical function of subsurface life. A model system to explore these interrelationships should offer a suitable range of geochemical regimes, carbon substrates and temperature gradients under which microbial life can generate energy and sustain itself. In this theory and hypothesis article, we make the case for the hydrothermally heated sediments of Guaymas Basin in the Gulf of California as a suitable model system where extensive temperature and geochemical gradients create distinct niches for active microbial populations in the hydrothermally influenced sedimentary subsurface that in turn intercept and process hydrothermally generated carbon sources. We synthesize the evidence for high-temperature microbial methane cycling and sulfate reduction at Guaymas Basin – with an eye on sulfate-dependent oxidation of abundant alkanes – and demonstrate the energetic feasibility of these latter types of deep subsurface life in previously drilled Guaymas Basin locations of Deep-Sea Drilling Project 64. PMID:25132832

  4. Microbial Community Responses to Organophosphate Substrate Additions in Contaminated Subsurface Sediments

    PubMed Central

    Martinez, Robert J.; Wu, Cindy H.; Beazley, Melanie J.; Andersen, Gary L.; Conrad, Mark E.; Hazen, Terry C.; Taillefert, Martial; Sobecky, Patricia A.

    2014-01-01

    Background Radionuclide- and heavy metal-contaminated subsurface sediments remain a legacy of Cold War nuclear weapons research and recent nuclear power plant failures. Within such contaminated sediments, remediation activities are necessary to mitigate groundwater contamination. A promising approach makes use of extant microbial communities capable of hydrolyzing organophosphate substrates to promote mineralization of soluble contaminants within deep subsurface environments. Methodology/Principal Findings Uranium-contaminated sediments from the U.S. Department of Energy Oak Ridge Field Research Center (ORFRC) Area 2 site were used in slurry experiments to identify microbial communities involved in hydrolysis of 10 mM organophosphate amendments [i.e., glycerol-2-phosphate (G2P) or glycerol-3-phosphate (G3P)] in synthetic groundwater at pH 5.5 and pH 6.8. Following 36 day (G2P) and 20 day (G3P) amended treatments, maximum phosphate (PO43−) concentrations of 4.8 mM and 8.9 mM were measured, respectively. Use of the PhyloChip 16S rRNA microarray identified 2,120 archaeal and bacterial taxa representing 46 phyla, 66 classes, 110 orders, and 186 families among all treatments. Measures of archaeal and bacterial richness were lowest under G2P (pH 5.5) treatments and greatest with G3P (pH 6.8) treatments. Members of the phyla Crenarchaeota, Euryarchaeota, Bacteroidetes, and Proteobacteria demonstrated the greatest enrichment in response to organophosphate amendments and the OTUs that increased in relative abundance by 2-fold or greater accounted for 9%–50% and 3%–17% of total detected Archaea and Bacteria, respectively. Conclusions/Significance This work provided a characterization of the distinct ORFRC subsurface microbial communities that contributed to increased concentrations of extracellular phosphate via hydrolysis of organophosphate substrate amendments. Within subsurface environments that are not ideal for reductive precipitation of uranium, strategies that

  5. Widespread distribution and high abundance of Rhizobium radiobacter within Mediterranean subsurface sediments.

    PubMed

    Süss, Jacqueline; Schubert, Karin; Sass, Henrik; Cypionka, Heribert; Overmann, Jörg; Engelen, Bert

    2006-10-01

    Eastern Mediterranean sediments are characterized by the occurrence of distinct, organic-rich layers, called sapropels. These harbour elevated microbial numbers in comparison with adjacent carbon-lean intermediate layers. A recently obtained culture collection from these sediments was composed of 20% of strains closely related to Rhizobium radiobacter, formerly classified as Agrobacterium tumefaciens. To prove and quantify the in situ abundance of R. radiobacter, a highly specific quantitative polymerase chain reaction (PCR) protocol was developed. To convert quantification results into cell numbers, the copy number of rrn operons per genome was determined. Southern hybridization showed that our isolates contained four operons. Finally, quantitative PCR was applied to 45 sediment samples obtained across the eastern Mediterranean. Rhizobium radiobacter was present in 38 of 45 samples indicating an almost ubiquitous distribution. In total, 25-40 000 cells per gram of sediment were detected, corresponding to 0.001-5.1% of the bacterial cells. In general, the relative and absolute abundance of R. radiobacter increased with depth and was higher in sapropels than in intermediate layers. This indicates that R. radiobacter forms an active population in up to 200 000 years old sapropels. The present study shows for the first time that a cultivated subsurface bacterium is highly abundant in this environment.

  6. Kosi megafan: Sub-surface stratigraphy, sediment provenance and paleoclimate proxies

    NASA Astrophysics Data System (ADS)

    Sinha, Rajiv; Yadav, Manish; Paul, Debajyoti; Chabaux, François; Granet, Mathieu

    2015-04-01

    The Kosi megafan is a well-known Himalayan megafan formed due to high sediment delivery of Kosi River and frequent migration of the trunk river. The topography of conical Kosi megafan is convex-upward and the numerous paleochannels on its surface are the remnants of westward movements of the Kosi during last 200 years. The sub-surface stratigraphy of Kosi megafan has been reconstructed after detailed facies analysis of the drill core sediments. Near-surface (~20 m) strata have pockets of mud and silt within large amalgamated sand bodies whereas shallow sub-surface (~50 m) deposits are sandy and devoid of mud and silt pockets. Luminescence dating of core sediments suggests that the Kosi megafan has been evolving at least since MIS 4. Depositional phases characterized by aggradation and lithological discontinuity preserved in sedimentary succession has signatures of multiple aggradational events and autocyclic movements of channels. Variable net deposition rates (0.3 - 2.4 mm/yr) since MIS 3, calculated in different cores, relate to channel residence times as well as major climatic shifts. Stratigraphic reconstruction suggests that the Kosi River has been a multi-channel system for the last 65 ka due to high sediment flux from the Himalaya. We have recorded five cycles of channel activity: (i) > 65ka (MIS4), (ii) 32 to 50ka (MIS3), (iii) 12 to 28ka (MIS2), (iv) 9 to 11ka (Early Holocene), and (v) 5ka to Modern (Late Holocene) in the studied cores. Multiple aggradational events and abandonment due to migration of the river show some correlation with the major climatic shifts, which in turn influenced the sediment flux from the Higher/Lesser Himalaya. Proximal to distal progradation of the megafan in response to climate and energy conditions reflects gradual decrease in flow energy through time or change in sediment supply from the hinterland. After confirming that the radiogenic isotopic ratios (87Sr/86Sr and 143Nd/144Nd) in Kosi core sediments are not affected by

  7. Impact of mercury on denitrification and denitrifying microbial communities in nitrate enrichments of subsurface sediments.

    PubMed

    Wang, Yanping; Wiatrowski, Heather A; John, Ria; Lin, Chu-Ching; Young, Lily Y; Kerkhof, Lee J; Yee, Nathan; Barkay, Tamar

    2013-02-01

    The contamination of groundwater with mercury (Hg) is an increasing problem worldwide. Yet, little is known about the interactions of Hg with microorganisms and their processes in subsurface environments. We tested the impact of Hg on denitrification in nitrate reducing enrichment cultures derived from subsurface sediments from the Oak Ridge Integrated Field Research Challenge site, where nitrate is a major contaminant and where bioremediation efforts are in progress. We observed an inverse relationship between Hg concentrations and onset and rates of denitrification in nitrate enrichment cultures containing between 53 and 1.1 μM of inorganic Hg; higher Hg concentrations increasingly extended the time to onset of denitrification and inhibited denitrification rates. Microbial community complexity, as indicated by terminal restriction fragment length polymorphism (tRFLP) analysis of the 16S rRNA genes, declined with increasing Hg concentrations; at the 312 nM Hg treatment, a single tRFLP peak was detected representing a culture of Bradyrhizobium sp. that possessed the merA gene indicating a potential for Hg reduction. A culture identified as Bradyrhizobium sp. strain FRC01 with an identical 16S rRNA sequence to that of the enriched peak in the tRFLP patterns, reduced Hg(II) to Hg(0) and carried merA whose amino acid sequence has 97 % identity to merA from the Proteobacteria and Firmicutes. This study demonstrates that in subsurface sediment incubations, Hg may inhibit denitrification and that inhibition may be alleviated when Hg resistant denitrifying Bradyrhizobium spp. detoxify Hg by its reduction to the volatile elemental form.

  8. Denitrifying bacteria isolated from terrestrial subsurface sediments exposed to mixed-waste contamination.

    PubMed

    Green, Stefan J; Prakash, Om; Gihring, Thomas M; Akob, Denise M; Jasrotia, Puja; Jardine, Philip M; Watson, David B; Brown, Steven D; Palumbo, Anthony V; Kostka, Joel E

    2010-05-01

    In terrestrial subsurface environments where nitrate is a critical groundwater contaminant, few cultivated representatives are available to verify the metabolism of organisms that catalyze denitrification. In this study, five species of denitrifying bacteria from three phyla were isolated from subsurface sediments exposed to metal radionuclide and nitrate contamination as part of the U.S. Department of Energy's Oak Ridge Integrated Field Research Challenge (OR-IFRC). Isolates belonged to the genera Afipia and Hyphomicrobium (Alphaproteobacteria), Rhodanobacter (Gammaproteobacteria), Intrasporangium (Actinobacteria), and Bacillus (Firmicutes). Isolates from the phylum Proteobacteria were complete denitrifiers, whereas the Gram-positive isolates reduced nitrate to nitrous oxide. rRNA gene analyses coupled with physiological and genomic analyses suggest that bacteria from the genus Rhodanobacter are a diverse population of denitrifiers that are circumneutral to moderately acidophilic, with a high relative abundance in areas of the acidic source zone at the OR-IFRC site. Based on genome analysis, Rhodanobacter species contain two nitrite reductase genes and have not been detected in functional-gene surveys of denitrifying bacteria at the OR-IFRC site. Nitrite and nitrous oxide reductase gene sequences were recovered from the isolates and from the terrestrial subsurface by designing primer sets mined from genomic and metagenomic data and from draft genomes of two of the isolates. We demonstrate that a combination of cultivation and genomic and metagenomic data is essential to the in situ characterization of denitrifiers and that current PCR-based approaches are not suitable for deep coverage of denitrifiers. Our results indicate that the diversity of denitrifiers is significantly underestimated in the terrestrial subsurface. PMID:20305024

  9. Denitrifying bacteria isolated from terrestrial subsurface sediments exposed to mixed-waste contamination.

    PubMed

    Green, Stefan J; Prakash, Om; Gihring, Thomas M; Akob, Denise M; Jasrotia, Puja; Jardine, Philip M; Watson, David B; Brown, Steven D; Palumbo, Anthony V; Kostka, Joel E

    2010-05-01

    In terrestrial subsurface environments where nitrate is a critical groundwater contaminant, few cultivated representatives are available to verify the metabolism of organisms that catalyze denitrification. In this study, five species of denitrifying bacteria from three phyla were isolated from subsurface sediments exposed to metal radionuclide and nitrate contamination as part of the U.S. Department of Energy's Oak Ridge Integrated Field Research Challenge (OR-IFRC). Isolates belonged to the genera Afipia and Hyphomicrobium (Alphaproteobacteria), Rhodanobacter (Gammaproteobacteria), Intrasporangium (Actinobacteria), and Bacillus (Firmicutes). Isolates from the phylum Proteobacteria were complete denitrifiers, whereas the Gram-positive isolates reduced nitrate to nitrous oxide. rRNA gene analyses coupled with physiological and genomic analyses suggest that bacteria from the genus Rhodanobacter are a diverse population of denitrifiers that are circumneutral to moderately acidophilic, with a high relative abundance in areas of the acidic source zone at the OR-IFRC site. Based on genome analysis, Rhodanobacter species contain two nitrite reductase genes and have not been detected in functional-gene surveys of denitrifying bacteria at the OR-IFRC site. Nitrite and nitrous oxide reductase gene sequences were recovered from the isolates and from the terrestrial subsurface by designing primer sets mined from genomic and metagenomic data and from draft genomes of two of the isolates. We demonstrate that a combination of cultivation and genomic and metagenomic data is essential to the in situ characterization of denitrifiers and that current PCR-based approaches are not suitable for deep coverage of denitrifiers. Our results indicate that the diversity of denitrifiers is significantly underestimated in the terrestrial subsurface.

  10. Denitrifying Bacteria Isolated from Terrestrial Subsurface Sediments Exposed to Mixed-Waste Contamination▿ †

    PubMed Central

    Green, Stefan J.; Prakash, Om; Gihring, Thomas M.; Akob, Denise M.; Jasrotia, Puja; Jardine, Philip M.; Watson, David B.; Brown, Steven D.; Palumbo, Anthony V.; Kostka, Joel E.

    2010-01-01

    In terrestrial subsurface environments where nitrate is a critical groundwater contaminant, few cultivated representatives are available to verify the metabolism of organisms that catalyze denitrification. In this study, five species of denitrifying bacteria from three phyla were isolated from subsurface sediments exposed to metal radionuclide and nitrate contamination as part of the U.S. Department of Energy's Oak Ridge Integrated Field Research Challenge (OR-IFRC). Isolates belonged to the genera Afipia and Hyphomicrobium (Alphaproteobacteria), Rhodanobacter (Gammaproteobacteria), Intrasporangium (Actinobacteria), and Bacillus (Firmicutes). Isolates from the phylum Proteobacteria were complete denitrifiers, whereas the Gram-positive isolates reduced nitrate to nitrous oxide. rRNA gene analyses coupled with physiological and genomic analyses suggest that bacteria from the genus Rhodanobacter are a diverse population of denitrifiers that are circumneutral to moderately acidophilic, with a high relative abundance in areas of the acidic source zone at the OR-IFRC site. Based on genome analysis, Rhodanobacter species contain two nitrite reductase genes and have not been detected in functional-gene surveys of denitrifying bacteria at the OR-IFRC site. Nitrite and nitrous oxide reductase gene sequences were recovered from the isolates and from the terrestrial subsurface by designing primer sets mined from genomic and metagenomic data and from draft genomes of two of the isolates. We demonstrate that a combination of cultivation and genomic and metagenomic data is essential to the in situ characterization of denitrifiers and that current PCR-based approaches are not suitable for deep coverage of denitrifiers. Our results indicate that the diversity of denitrifiers is significantly underestimated in the terrestrial subsurface. PMID:20305024

  11. Radioiodine sorption/desorption and speciation transformation by subsurface sediments from the Hanford Site.

    PubMed

    Xu, Chen; Kaplan, Daniel I; Zhang, Saijin; Athon, Matthew; Ho, Yi-Fang; Li, Hsiu-Ping; Yeager, Chris M; Schwehr, Kathleen A; Grandbois, Russell; Wellman, Dawn; Santschi, Peter H

    2015-01-01

    During the last few decades, considerable research efforts have been extended to identify more effective remediation treatment technologies to lower the (129)I concentrations to below federal drinking water standards at the Hanford Site (Richland, USA). Few studies have taken iodate into consideration, though recently iodate, instead of iodide, was identified as the major species in the groundwater of 200-West Area within the Hanford Site. The objective of this study was thus to quantify and understand aqueous radioiodine species transformations and uptake by three sediments collected from the semi-arid, carbonate-rich environment of the Hanford subsurface. All three sediments reduced iodate (IO3(-)) to iodide (I(-)), but the loamy-sand sediment reduced more IO3(-) (100% reduced within 7 days) than the two sand-textured sediments (∼20% reduced after 28 days). No dissolved organo-iodine species were observed in any of these studies. Iodate uptake Kd values ([Isolid]/[Iaq]; 0.8-7.6 L/kg) were consistently and appreciably greater than iodide Kd values (0-5.6 L/kg). Furthermore, desorption Kd values (11.9-29.8 L/kg) for both iodate and iodide were consistently and appreciably greater than uptake Kd values (0-7.6 L/kg). Major fractions of iodine associated with the sediments were unexpectedly strongly bound, such that only 0.4-6.6 % of the total sedimentary iodine could be exchanged from the surface with KCl solution, and 0-1.2% was associated with Fe or Mn oxides (weak NH2HCl/HNO3 extractable fraction). Iodine incorporated into calcite accounted for 2.9-39.4% of the total sedimentary iodine, whereas organic carbon (OC) is likely responsible for the residual iodine (57.1-90.6%) in sediments. The OC, even at low concentrations, appeared to be controlling iodine binding to the sediments, as it was found that the greater the OC concentrations in the sediments, the greater the values of uptake Kd, desorption Kd, and the greater residual iodine concentrations (non

  12. Enumeration and Characterization of Iron(III)-Reducing Microbial Communities from Acidic Subsurface Sediments Contaminated with Uranium(VI)

    PubMed Central

    Petrie, Lainie; North, Nadia N.; Dollhopf, Sherry L.; Balkwill, David L.; Kostka, Joel E.

    2003-01-01

    Iron(III)-reducing bacteria have been demonstrated to rapidly catalyze the reduction and immobilization of uranium(VI) from contaminated subsurface sediments. Thus, these organisms may aid in the development of bioremediation strategies for uranium contamination, which is prevalent in acidic subsurface sediments at U.S. government facilities. Iron(III)-reducing enrichment cultures were initiated from pristine and contaminated (high in uranium, nitrate; low pH) subsurface sediments at pH 7 and pH 4 to 5. Enumeration of Fe(III)-reducing bacteria yielded cell counts of up to 240 cells ml−1 for the contaminated and background sediments at both pHs with a range of different carbon sources (glycerol, acetate, lactate, and glucose). In enrichments where nitrate contamination was removed from the sediment by washing, MPN counts of Fe(III)-reducing bacteria increased substantially. Sediments of lower pH typically yielded lower counts of Fe(III)-reducing bacteria in lactate- and acetate-amended enrichments, but higher counts were observed when glucose was used as an electron donor in acidic enrichments. Phylogenetic analysis of 16S rRNA gene sequences extracted from the highest positive MPN dilutions revealed that the predominant members of Fe(III)-reducing consortia from background sediments were closely related to members of the Geobacteraceae family, whereas a recently characterized Fe(III) reducer (Anaeromyxobacter sp.) and organisms not previously shown to reduce Fe(III) (Paenibacillus and Brevibacillus spp.) predominated in the Fe(III)-reducing consortia of contaminated sediments. Analysis of enrichment cultures by terminal restriction fragment length polymorphism (T-RFLP) strongly supported the cloning and sequencing results. Dominant members of the Fe(III)-reducing consortia were observed to be stable over several enrichment culture transfers by T-RFLP in conjunction with measurements of Fe(III) reduction activity and carbon substrate utilization. Enrichment

  13. Microbial physiology-based model of ethanol metabolism in subsurface sediments

    NASA Astrophysics Data System (ADS)

    Jin, Qusheng; Roden, Eric E.

    2011-07-01

    A biogeochemical reaction model was developed based on microbial physiology to simulate ethanol metabolism and its influence on the chemistry of anoxic subsurface environments. The model accounts for potential microbial metabolisms that degrade ethanol, including those that oxidize ethanol directly or syntrophically by reducing different electron acceptors. Out of the potential metabolisms, those that are active in the environment can be inferred by fitting the model to experimental observations. This approach was applied to a batch sediment slurry experiment that examined ethanol metabolism in uranium-contaminated aquifer sediments from Area 2 at the U.S. Department of Energy Field Research Center in Oak Ridge, TN. According to the simulation results, complete ethanol oxidation by denitrification, incomplete ethanol oxidation by ferric iron reduction, ethanol fermentation to acetate and H 2, hydrogenotrophic sulfate reduction, and acetoclastic methanogenesis: all contributed significantly to the degradation of ethanol in the aquifer sediments. The assemblage of the active metabolisms provides a frame work to explore how ethanol amendment impacts the chemistry of the environment, including the occurrence and levels of uranium. The results can also be applied to explore how diverse microbial metabolisms impact the progress and efficacy of bioremediation strategies.

  14. Influence of acidic and alkaline waste solution properties on uranium migration in subsurface sediments

    NASA Astrophysics Data System (ADS)

    Szecsody, Jim E.; Truex, Mike J.; Qafoku, Nikolla P.; Wellman, Dawn M.; Resch, Tom; Zhong, Lirong

    2013-08-01

    This study shows that acidic and alkaline wastes co-disposed with uranium into subsurface sediments have significant impact on changes in uranium retardation, concentration, and mass during downward migration. For uranium co-disposal with acidic wastes, significant rapid (i.e., hours) carbonate and slow (i.e., 100 s of hours) clay dissolution resulted, releasing significant sediment-associated uranium, but the extent of uranium release and mobility change was controlled by the acid mass added relative to the sediment proton adsorption capacity. Mineral dissolution in acidic solutions (pH 2) resulted in a rapid (< 10 h) increase in aqueous carbonate (with Ca2 +, Mg2 +) and phosphate and a slow (100 s of hours) increase in silica, Al3 +, and K+, likely from 2:1 clay dissolution. Infiltration of uranium with a strong acid resulted in significant shallow uranium mineral dissolution and deeper uranium precipitation (likely as phosphates and carbonates) with downward uranium migration of three times greater mass at a faster velocity relative to uranium infiltration in pH neutral groundwater. In contrast, mineral dissolution in an alkaline environment (pH 13) resulted in a rapid (< 10 h) increase in carbonate, followed by a slow (10 s to 100 s of hours) increase in silica concentration, likely from montmorillonite, muscovite, and kaolinite dissolution. Infiltration of uranium with a strong base resulted in not only uranium-silicate precipitation (presumed Na-boltwoodite) but also desorption of natural uranium on the sediment due to the high ionic strength solution, or 60% greater mass with greater retardation compared with groundwater. Overall, these results show that acidic or alkaline co-contaminant disposal with uranium can result in complex depth- and time-dependent changes in uranium dissolution/precipitation reactions and uranium sorption, which alter the uranium migration mass, concentration, and velocity.

  15. Fungal diversity from deep marine subsurface sediments (IODP 317, Canterbury Basin, New Zealand)

    NASA Astrophysics Data System (ADS)

    Redou, V.; Arzur, D.; Burgaud, G.; Barbier, G.

    2012-12-01

    Recent years have seen a growing interest regarding micro-eukaryotic communities in extreme environments as a third microbial domain after Bacteria and Archaea. However, knowledge is still scarce and the diversity of micro-eukaryotes in such environments remains hidden and their ecological role unknown. Our research program is based on the deep sedimentary layers of the Canterbury Basin in New Zealand (IODP 317) from the subsurface to the record depth of 1884 meters below seafloor. The objectives of our study are (i) to assess the genetic diversity of fungi in deep-sea sediments and (ii) identify the functional part in order to better understand the origin and the ecological role of fungal communities in this extreme ecosystem. Fingerprinting-based methods using capillary electrophoresis single-strand conformation polymorphism and denaturing high-performance liquid chromatography were used as a first step to raise our objectives. Molecular fungal diversity was assessed using amplification of ITS1 (Internal Transcribed Spacer 1) as a biomarker on 11 samples sediments from 3.76 to 1884 meters below seafloor. Fungal molecular signatures were detected throughout the sediment core. The phyla Ascomycota and Basidiomycota were revealed with DNA as well as cDNA. Most of the phylotypes are affiliated to environmental sequences and some to common fungal cultured species. The discovery of a present and metabolically active fungal component in this unique ecosystem allows some interesting first hypotheses that will be further combined to culture-based methods and deeper molecular methods (454 pyrosequencing) to highlight essential informations regarding physiology and ecological role of fungal communities in deep marine sediments.

  16. Microbial Diversity in Coastal Subsurface Sediments: a Cultivation Approach Using Various Electron Acceptors and Substrate Gradients

    PubMed Central

    Köpke, Beate; Wilms, Reinhard; Engelen, Bert; Cypionka, Heribert; Sass, Henrik

    2005-01-01

    Microbial communities in coastal subsurface sediments are scarcely investigated and have escaped attention so far. But since they are likely to play an important role in biogeochemical cycles, knowledge of their composition and ecological adaptations is important. Microbial communities in tidal sediments were investigated along the geochemical gradients from the surface down to a depth of 5.5 m. Most-probable-number (MPN) series were prepared with a variety of different carbon substrates, each at a low concentration, in combination with different electron acceptors such as iron and manganese oxides. These achieved remarkably high cultivation efficiencies (up to 23% of the total cell counts) along the upper 200 cm. In the deeper sediment layers, MPN counts dropped significantly. Parallel to the liquid enrichment cultures in the MPN series, gradient cultures with embedded sediment subcores were prepared as an additional enrichment approach. In total, 112 pure cultures were isolated; they could be grouped into 53 different operational taxonomic units (OTU). The isolates belonged to the Proteobacteria, “Bacteroidetes,” “Fusobacteria,” Actinobacteria, and “Firmicutes.” Each cultivation approach yielded a specific set of isolates that in general were restricted to this single isolation procedure. Analysis of the enrichment cultures by PCR and denaturing gradient gel electrophoresis revealed an even higher diversity in the primary enrichments that was only partially reflected by the culture collection. The majority of the isolates grew well under anoxic conditions, by fermentation, or by anaerobic respiration with nitrate, sulfate, ferrihydrite, or manganese oxides as electron acceptors. PMID:16332756

  17. Influence of acidic and alkaline waste solution properties on uranium migration in subsurface sediments.

    PubMed

    Szecsody, Jim E; Truex, Mike J; Qafoku, Nikolla P; Wellman, Dawn M; Resch, Tom; Zhong, Lirong

    2013-08-01

    This study shows that acidic and alkaline wastes co-disposed with uranium into subsurface sediments have significant impact on changes in uranium retardation, concentration, and mass during downward migration. For uranium co-disposal with acidic wastes, significant rapid (i.e., hours) carbonate and slow (i.e., 100 s of hours) clay dissolution resulted, releasing significant sediment-associated uranium, but the extent of uranium release and mobility change was controlled by the acid mass added relative to the sediment proton adsorption capacity. Mineral dissolution in acidic solutions (pH2) resulted in a rapid (<10 h) increase in aqueous carbonate (with Ca(2+), Mg(2+)) and phosphate and a slow (100 s of hours) increase in silica, Al(3+), and K(+), likely from 2:1 clay dissolution. Infiltration of uranium with a strong acid resulted in significant shallow uranium mineral dissolution and deeper uranium precipitation (likely as phosphates and carbonates) with downward uranium migration of three times greater mass at a faster velocity relative to uranium infiltration in pH neutral groundwater. In contrast, mineral dissolution in an alkaline environment (pH13) resulted in a rapid (<10h) increase in carbonate, followed by a slow (10 s to 100 s of hours) increase in silica concentration, likely from montmorillonite, muscovite, and kaolinite dissolution. Infiltration of uranium with a strong base resulted in not only uranium-silicate precipitation (presumed Na-boltwoodite) but also desorption of natural uranium on the sediment due to the high ionic strength solution, or 60% greater mass with greater retardation compared with groundwater. Overall, these results show that acidic or alkaline co-contaminant disposal with uranium can result in complex depth- and time-dependent changes in uranium dissolution/precipitation reactions and uranium sorption, which alter the uranium migration mass, concentration, and velocity.

  18. Influence of acidic and alkaline waste solution properties on uranium migration in subsurface sediments.

    PubMed

    Szecsody, Jim E; Truex, Mike J; Qafoku, Nikolla P; Wellman, Dawn M; Resch, Tom; Zhong, Lirong

    2013-08-01

    This study shows that acidic and alkaline wastes co-disposed with uranium into subsurface sediments have significant impact on changes in uranium retardation, concentration, and mass during downward migration. For uranium co-disposal with acidic wastes, significant rapid (i.e., hours) carbonate and slow (i.e., 100 s of hours) clay dissolution resulted, releasing significant sediment-associated uranium, but the extent of uranium release and mobility change was controlled by the acid mass added relative to the sediment proton adsorption capacity. Mineral dissolution in acidic solutions (pH2) resulted in a rapid (<10 h) increase in aqueous carbonate (with Ca(2+), Mg(2+)) and phosphate and a slow (100 s of hours) increase in silica, Al(3+), and K(+), likely from 2:1 clay dissolution. Infiltration of uranium with a strong acid resulted in significant shallow uranium mineral dissolution and deeper uranium precipitation (likely as phosphates and carbonates) with downward uranium migration of three times greater mass at a faster velocity relative to uranium infiltration in pH neutral groundwater. In contrast, mineral dissolution in an alkaline environment (pH13) resulted in a rapid (<10h) increase in carbonate, followed by a slow (10 s to 100 s of hours) increase in silica concentration, likely from montmorillonite, muscovite, and kaolinite dissolution. Infiltration of uranium with a strong base resulted in not only uranium-silicate precipitation (presumed Na-boltwoodite) but also desorption of natural uranium on the sediment due to the high ionic strength solution, or 60% greater mass with greater retardation compared with groundwater. Overall, these results show that acidic or alkaline co-contaminant disposal with uranium can result in complex depth- and time-dependent changes in uranium dissolution/precipitation reactions and uranium sorption, which alter the uranium migration mass, concentration, and velocity. PMID:23851265

  19. Geochemical and Mineralogical Investigation of Uranium in Multi–element Contaminated, Organic–rich Subsurface Sediment

    SciTech Connect

    Qafoku, Nikolla; Gartman, Brandy N.; Kukkadapu, Ravi K.; Arey, Bruce W.; Williams, Kenneth H.; Mouser, Paula J.; Heald, Steve M.; Bargar, John R.; Janot, Noemie; Yabusaki, Steven B.; Long, Philip E.

    2014-03-02

    Alluvial sediments characterized by an abundance of refractory or lignitic organic carbon compounds and reduced Fe and S bearing mineral phases have been identified through drilling activities at the U.S. Department of Energy’s (DOE) Integrated Field Research Challenge (IFRC) site at Rifle, CO. Regions of the subsurface from which such sediments are derived are referred to as Naturally Reduced Zones (NRZ). We conducted a study with NRZ sediments with the objective to: i.) Characterize solid phase contamination of U and other co-contaminants; ii.) Document the occurrence of potential U host minerals; iii.) Determine U valence state and micron scale spatial association with co-contaminants. Macroscopic (wet chemical batch extractions and a column experiment), microscopic (SEM-EDS), and spectroscopic (Mössbauer, µ-XRF and XANES) techniques were employed. Results showed that sediments’ solid phase had significant concentrations of U, S, As, Zn, V, Cr, Cu and Se, and a remarkable assortment of potential U hosts (sorbents and/or electron donors), such as Fe oxides (hematite, magnetite, Al-substituted goethite), siderite, reduced Fe(II) bearing clays, sulfides of different types, Zn sulfide framboids and multi – element sulfides. Multi-contaminants, micron size (ca. 5 to 30 µm) areas of mainly U(IV) and some U(VI), and/or other electron scavengers or donors such as Se, As, Cr, and V were discovered in the sediments, suggesting complex micron-scale system responses to transient redox conditions, and different extent and rates of competing U redox reactions than those of single contaminant systems. Collectively, the results improve our understanding and ability to predict U and NRZ’s complex behavior and will delineate future research directions to further study both the natural attenuation and persistence of contaminant plumes and their contribution to groundwater contamination.

  20. Influence of Acidic and Alkaline Waste Solution Properties on Uranium Migration in Subsurface Sediments

    SciTech Connect

    Szecsody, James E.; Truex, Michael J.; Qafoku, Nikolla; Wellman, Dawn M.; Resch, Charles T.; Zhong, Lirong

    2013-08-01

    This study shows that acidic and alkaline wastes co-disposed with uranium into subsurface sediments has significant impact on changes in uranium retardation, concentration, and mass during downward migration. For uranium co-disposal with acidic wastes, significant rapid (i.e., hours) carbonate and slow (i.e., 100s of hours) clay dissolution resulted, releasing significant sediment-associated uranium, but the extent of uranium release and mobility change was controlled by the acid mass added relative to the sediment proton adsorption capacity. Mineral dissolution in acidic solutions (pH 2) resulted in a rapid (< 10 h) increase in aqueous carbonate (with Ca2+, Mg2+) and phosphate and a slow (100s of hours) increase in silica, Al3+, and K+, likely from 2:1 clay dissolution. Infiltration of uranium with a strong acid resulted in significant shallow uranium mineral dissolution and deeper uranium precipitation (likely as phosphates and carbonates) with downward uranium migration of three times greater mass at a faster velocity relative to uranium infiltration in pH neutral groundwater. In contrast, mineral dissolution in an alkaline environment (pH 13) resulted in a rapid (< 10 h) increase in carbonate, followed by a slow (10s to 100s of hours) increase in silica concentration, likely from montmorillonite, muscovite, and kaolinite dissolution. Infiltration of uranium with a strong base resulted in uranium-silicate precipitation (presumed Na-boltwoodite) but also desorption of natural uranium on the sediment due to the high ionic strength solution, or 60% greater mass with greater retardation compared with groundwater. Overall, these results show that acidic or alkaline co-contaminant disposal with uranium can result in complex depth- and time-dependent changes in uranium dissolution/precipitation reactions and uranium sorption, which alter the uranium migration mass, concentration, and velocity.

  1. Acidobacteria Phylum Sequences in Uranium-Contaminated Subsurface Sediments Greatly Expand the Known Diversity within the Phylum▿ †

    PubMed Central

    Barns, Susan M.; Cain, Elizabeth C.; Sommerville, Leslie; Kuske, Cheryl R.

    2007-01-01

    The abundance and composition of bacteria of the phylum Acidobacteria were surveyed in subsurface sediments from uranium-contaminated sites using amplification of 16S rRNA genes followed by clone/sequence analysis. Analysis of sequences from this study and public databases produced a revised and greatly expanded phylogeny of the Acidobacteria phylum consisting of 26 subgroups. PMID:17337544

  2. ANME-2D Archaea Catalyze Methane Oxidation in Deep Subsurface Sediments Independent of Nitrate Reduction

    NASA Astrophysics Data System (ADS)

    Hernsdorf, A. W.; Amano, Y.; Suzuki, Y.; Ise, K.; Thomas, B. C.; Banfield, J. F.

    2015-12-01

    Terrestrial sediments are an important global reservoir for methane. Microorganisms in the deep subsurface play a critical role in the methane cycle, yet much remains to be learned about their diversity and metabolisms. To provide more comprehensive insight into the microbiology of the methane cycle in the deep subsurface, we conducted a genome-resolved study of samples collected from the Horonobe Underground Research Laboratory (HURL), Japan. Groundwater samples were obtained from three boreholes from a depth range of between 140 m and 250 m in two consecutive years. Groundwater was filtered and metagenomic DNA extracted and sequenced, and the sequence data assembled. Based on the sequences of phylogenetically informative genes on the assembled fragments, we detected a high degree of overlap in community composition across a vertical transect within one borehole at the two sampling times. However, there was comparatively little similarity observed among communities across boreholes. Spatial and temporal abundance patterns were used in combination with tetranucleotide signatures of assembled genome fragments to bin the data and reconstruct over 200 unique draft genomes, of which 137 are considered to be of high quality (>90% complete). The deepest samples from one borehole were highly dominated by an archaeon identified as ANME-2D; this organism was also present at lower abundance in all other samples from that borehole. Also abundant in these microbial communities were novel members of the Gammaproteobacteria, Saccharibacteria (TM7) and Tenericute phyla. Notably, a ~2 Mbp draft genome for the ANME-2D archaeon was reconstructed. As expected, the genome encodes all of the genes predicted to be involved in the reverse methanogenesis pathway. In contrast with the previously reported ANME2-D genome, the HURL ANME-2D genome lacks the capacity to reduce nitrate. However, we identified many multiheme cytochromes with closest similarity to those of the known Fe

  3. Change in Bacterial Community Structure during In Situ Biostimulation of Subsurface Sediment Cocontaminated with Uranium and Nitrate

    PubMed Central

    North, Nadia N.; Dollhopf, Sherry L.; Petrie, Lainie; Istok, Jonathan D.; Balkwill, David L.; Kostka, Joel E.

    2004-01-01

    Previous studies have demonstrated that metal-reducing microorganisms can effectively promote the precipitation and removal of uranium from contaminated groundwater. Microbial communities were stimulated in the acidic subsurface by pH neutralization and addition of an electron donor to wells. In single-well push-pull tests at a number of treated sites, nitrate, Fe(III), and uranium were extensively reduced and electron donors (glucose, ethanol) were consumed. Examination of sediment chemistry in cores sampled immediately adjacent to treated wells 3.5 months after treatment revealed that sediment pH increased substantially (by 1 to 2 pH units) while nitrate was largely depleted. A large diversity of 16S rRNA gene sequences were retrieved from subsurface sediments, including species from the α, β, δ, and γ subdivisions of the class Proteobacteria, as well as low- and high-G+C gram-positive species. Following in situ biostimulation of microbial communities within contaminated sediments, sequences related to previously cultured metal-reducing δ-Proteobacteria increased from 5% to nearly 40% of the clone libraries. Quantitative PCR revealed that Geobacter-type 16S rRNA gene sequences increased in biostimulated sediments by 1 to 2 orders of magnitude at two of the four sites tested. Evidence from the quantitative PCR analysis corroborated information obtained from 16S rRNA gene clone libraries, indicating that members of the δ-Proteobacteria subdivision, including Anaeromyxobacter dehalogenans-related and Geobacter-related sequences, are important metal-reducing organisms in acidic subsurface sediments. This study provides the first cultivation-independent analysis of the change in metal-reducing microbial communities in subsurface sediments during an in situ bioremediation experiment. PMID:15294831

  4. Nontoxic chemical process for in situ permeability enhancement and accelerated decontamination of fine-grain subsurface sediments

    DOEpatents

    Kansa, Edward J.; Wijesinghe, Ananda M.; Viani, Brian E.

    1997-01-01

    The remediation of heterogeneous subsurfaces is extremely time consuming and expensive with current and developing technologies. Although such technologies can adequately remove contaminants in the high hydraulic conductivity, coarse-grained sediments, they cannot access the contaminated low hydraulic conductivity fine-grained sediments. The slow bleed of contaminants from the fine-grained sediments is the primary reason why subsurface remediation is so time-consuming and expensive. This invention addresses the problem of remediating contaminated fine-grained sediments. It is intended that, in the future, a heterogeneous site be treated by a hybrid process that first remediates the high hydraulic conductivity, coarse-grained sediments, to be followed by the process, described in this invention, to treat the contaminated low hydraulic conductivity fine-grained sediments. The invention uses cationic flocculents and organic solvents to collapse the swelling negative double layer surrounding water saturated clay particles, causing a flocculated, cracked clay structure. The modification of the clay fabric in fine-grained sediments dramatically increases the hydraulic conductivity of previously very tight clays many orders of magnitude.

  5. Nontoxic chemical process for in situ permeability enhancement and accelerated decontamination of fine-grain subsurface sediments

    DOEpatents

    Kansa, E.J.; Wijesinghe, A.M.; Viani, B.E.

    1997-01-14

    The remediation of heterogeneous subsurfaces is extremely time consuming and expensive with current and developing technologies. Although such technologies can adequately remove contaminants in the high hydraulic conductivity, coarse-grained sediments, they cannot access the contaminated low hydraulic conductivity fine-grained sediments. The slow bleed of contaminants from the fine-grained sediments is the primary reason why subsurface remediation is so time-consuming and expensive. This invention addresses the problem of remediating contaminated fine-grained sediments. It is intended that, in the future, a heterogeneous site be treated by a hybrid process that first remediates the high hydraulic conductivity, coarse-grained sediments, to be followed by the process, described in this invention, to treat the contaminated low hydraulic conductivity fine-grained sediments. The invention uses cationic flocculants and organic solvents to collapse the swelling negative double layer surrounding water saturated clay particles, causing a flocculated, cracked clay structure. The modification of the clay fabric in fine-grained sediments dramatically increases the hydraulic conductivity of previously very tight clays many orders of magnitude. 8 figs.

  6. Modeling subsurface transport in extensive glaciofluvial and littoral sediments to remediate a municipal drinking water aquifer

    NASA Astrophysics Data System (ADS)

    Bergvall, M.; Grip, H.; Sjöström, J.; Laudon, H.

    2011-07-01

    Few studies have been carried out that cover the entire transport process of pesticides, from application at the soil surface, through subsurface transport, to contamination of drinking water in esker aquifers. In formerly glaciated regions, such as Scandinavia, many of the most important groundwater resources are situated in glaciofluvial eskers. The purpose of the present study was to model and identify significant processes that govern subsurface transport of pesticides in extensive glaciofluvial and littoral sediments. To simulate the transport processes, we coupled a vadose zone model at soil profile scale to a regional groundwater flow model. The model was applied to a municipal drinking-water aquifer, contaminated with the pesticide-metabolite BAM (2,6-dichlorobenzoamide). At regional scale, with the combination of a ten-meter-deep vadose zone and coarse texture, the observed concentrations could be described by the model without assuming preferential flow. A sensitivity analysis revealed that hydraulic conductivity in the aquifer and infiltration rate accounted for almost half of the model uncertainty. The calibrated model was applied to optimize the location of extraction wells for remediation, which were used to validate the predictive modeling. Running a worst-case scenario, the model showed that the establishment of two remediation wells would clean the aquifer in four years, compared to nine years without them. Further development of the model would require additional field measurements in order to improve the description of macrodispersion in deep, sandy vadose zones. We also suggest that future research should focus on characterization of the variability of hydraulic conductivity and its effect on contaminant transport in eskers.

  7. Final report - Reduction of mercury in saturated subsurface sediments and its potential to mobilize mercury in its elemental form

    SciTech Connect

    Bakray, Tamar

    2013-06-13

    The goal of our project was to investigate Hg(II) reduction in the deep subsurface. We focused on microbial and abiotic pathways of reduction and explored how it affected the toxicity and mobility of Hg in this unique environment. The project’s tasks included: 1. Examining the role of mer activities in the reduction of Hg(II) in denitrifying enrichment cultures; 2. Investigating the biotic/abiotic reduction of Hg(II) under iron reducing conditions; 3. Examining Hg(II) redox transformations under anaerobic conditions in subsurface sediments from DOE sites.

  8. Plutonium and 210Pb distributions in northeast Atlantic sediments: subsurface anomalies caused by non-local mixing

    NASA Astrophysics Data System (ADS)

    Smith, John Norton; Boudreau, Bernard P.; Noshkin, Victor

    1986-12-01

    The depth distributions of 210Pb and 239,240Pu measured in a suite of box cores collected from water depths of 4000-5000 m in the northeast Atlantic Ocean exhibit pronounced subsurface maxima caused by sediment reworking by benthic infauna. Small-scale spatial heterogeneity in bioturbation rates is indicated by large differences in tracer profiles from duplicate cores separated only by a few centimeters. 210Pb and 239,240Pu activity distributions from each subcore exhibit a high degree of correlation, and most tracer profiles exhibit one or more subsurface maxima. One-dimensional, "biodiffusion" analogue models do not adequately simulate the principal features of this data set. However, an inverse "conveyer belt" mixing model which simulates subsurface egestion (or a functionally equivalent process) of surficial material which is enriched both in organic debris and radioactive tracers can reproduce the subsurface tracer maxima. Single-event and continuous subsurface egestion models have been formulated and solved for different "feeding rates" and background biodiffusive fields. The single-event model provides a better fit to the data and, in particular, ensures the observed, high degree of correlation between the 210Pb and 239,240Pu activity profiles, regardless of the different tracer input functions. The most likely candidate responsible for subsurface tracer egestion is a large infaunal worm of the phylum Sipunculida which dominates the biomass below a depth of 3 cm.

  9. Phylogenetic and Functional Diversity of Microbial Communities Associated with Subsurface Sediments of the Sonora Margin, Guaymas Basin

    PubMed Central

    Vigneron, Adrien; Cruaud, Perrine; Roussel, Erwan G.; Pignet, Patricia; Caprais, Jean-Claude; Callac, Nolwenn; Ciobanu, Maria-Cristina; Godfroy, Anne; Cragg, Barry A.; Parkes, John R.; Van Nostrand, Joy D.; He, Zhili; Zhou, Jizhong; Toffin, Laurent

    2014-01-01

    Subsurface sediments of the Sonora Margin (Guaymas Basin), located in proximity of active cold seep sites were explored. The taxonomic and functional diversity of bacterial and archaeal communities were investigated from 1 to 10 meters below the seafloor. Microbial community structure and abundance and distribution of dominant populations were assessed using complementary molecular approaches (Ribosomal Intergenic Spacer Analysis, 16S rRNA libraries and quantitative PCR with an extensive primers set) and correlated to comprehensive geochemical data. Moreover the metabolic potentials and functional traits of the microbial community were also identified using the GeoChip functional gene microarray and metabolic rates. The active microbial community structure in the Sonora Margin sediments was related to deep subsurface ecosystems (Marine Benthic Groups B and D, Miscellaneous Crenarchaeotal Group, Chloroflexi and Candidate divisions) and remained relatively similar throughout the sediment section, despite defined biogeochemical gradients. However, relative abundances of bacterial and archaeal dominant lineages were significantly correlated with organic carbon quantity and origin. Consistently, metabolic pathways for the degradation and assimilation of this organic carbon as well as genetic potentials for the transformation of detrital organic matters, hydrocarbons and recalcitrant substrates were detected, suggesting that chemoorganotrophic microorganisms may dominate the microbial community of the Sonora Margin subsurface sediments. PMID:25099369

  10. Phylogenetic and functional diversity of microbial communities associated with subsurface sediments of the Sonora Margin, Guaymas Basin.

    PubMed

    Vigneron, Adrien; Cruaud, Perrine; Roussel, Erwan G; Pignet, Patricia; Caprais, Jean-Claude; Callac, Nolwenn; Ciobanu, Maria-Cristina; Godfroy, Anne; Cragg, Barry A; Parkes, John R; Van Nostrand, Joy D; He, Zhili; Zhou, Jizhong; Toffin, Laurent

    2014-01-01

    Subsurface sediments of the Sonora Margin (Guaymas Basin), located in proximity of active cold seep sites were explored. The taxonomic and functional diversity of bacterial and archaeal communities were investigated from 1 to 10 meters below the seafloor. Microbial community structure and abundance and distribution of dominant populations were assessed using complementary molecular approaches (Ribosomal Intergenic Spacer Analysis, 16S rRNA libraries and quantitative PCR with an extensive primers set) and correlated to comprehensive geochemical data. Moreover the metabolic potentials and functional traits of the microbial community were also identified using the GeoChip functional gene microarray and metabolic rates. The active microbial community structure in the Sonora Margin sediments was related to deep subsurface ecosystems (Marine Benthic Groups B and D, Miscellaneous Crenarchaeotal Group, Chloroflexi and Candidate divisions) and remained relatively similar throughout the sediment section, despite defined biogeochemical gradients. However, relative abundances of bacterial and archaeal dominant lineages were significantly correlated with organic carbon quantity and origin. Consistently, metabolic pathways for the degradation and assimilation of this organic carbon as well as genetic potentials for the transformation of detrital organic matters, hydrocarbons and recalcitrant substrates were detected, suggesting that chemoorganotrophic microorganisms may dominate the microbial community of the Sonora Margin subsurface sediments.

  11. The role of nanopores on U(VI) sorption and redox behavior in U(VI)-contaminated subsurface sediments

    SciTech Connect

    Xu, Huifang; Roden, Eric E.; Kemner, Kenneth M.; Jung, Hun-Bok; Konishi, Hiromi; Boyanov, Maxim; Sun, Yubing; Mishra, Bhoopesh

    2013-10-16

    Most reactive surfaces in clay-dominated sediments are present within nanopores (pores of nm dimension). The behavior of geological fluids and minerals in nanopores is significantly different from those in normal non-nanoporous environments. The effect of nanopore surfaces on U(VI) sorption/desorption and reduction is likely to be significant in clay-rich subsurface environments. Our research results from both model nanopore system and natural sediments from both model system (synthetic nanopore alumina) and sediments from the ORNL Field Research Center prove that U(VI) sorption on nanopore surfaces can be greatly enhanced by nanopore confinement environments. The results from the project provide advanced mechanistic, quantitative information on the physiochemical controls on uranium sorption and redox behavior in subsurface sediments. The influence of nanopore surfaces on coupled uranium sorption/desorption and reduction processes is significant in virtually all subsurface environments, because most reactive surfaces are in fact nanopore surfaces. The results will enhance transfer of our laboratory-based research to a major field research initiative where reductive uranium immobilization is being investigated. Our results will also provide the basic science for developing in-situ colloidal barrier of nanoporous alumina in support of environmental remediation and long term stewardship of DOE sites.

  12. Microbial Communities and Organic Matter Composition in Surface and Subsurface Sediments of the Helgoland Mud Area, North Sea

    PubMed Central

    Oni, Oluwatobi E.; Schmidt, Frauke; Miyatake, Tetsuro; Kasten, Sabine; Witt, Matthias; Hinrichs, Kai-Uwe; Friedrich, Michael W.

    2015-01-01

    The role of microorganisms in the cycling of sedimentary organic carbon is a crucial one. To better understand relationships between molecular composition of a potentially bioavailable fraction of organic matter and microbial populations, bacterial and archaeal communities were characterized using pyrosequencing-based 16S rRNA gene analysis in surface (top 30 cm) and subsurface/deeper sediments (30–530 cm) of the Helgoland mud area, North Sea. Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) was used to characterize a potentially bioavailable organic matter fraction (hot-water extractable organic matter, WE-OM). Algal polymer-associated microbial populations such as members of the Gammaproteobacteria, Bacteroidetes, and Verrucomicrobia were dominant in surface sediments while members of the Chloroflexi (Dehalococcoidales and candidate order GIF9) and Miscellaneous Crenarchaeota Groups (MCG), both of which are linked to degradation of more recalcitrant, aromatic compounds and detrital proteins, were dominant in subsurface sediments. Microbial populations dominant in subsurface sediments (Chloroflexi, members of MCG, and Thermoplasmata) showed strong correlations to total organic carbon (TOC) content. Changes of WE-OM with sediment depth reveal molecular transformations from oxygen-rich [high oxygen to carbon (O/C), low hydrogen to carbon (H/C) ratios] aromatic compounds and highly unsaturated compounds toward compounds with lower O/C and higher H/C ratios. The observed molecular changes were most pronounced in organic compounds containing only CHO atoms. Our data thus, highlights classes of sedimentary organic compounds that may serve as microbial energy sources in methanic marine subsurface environments. PMID:26635758

  13. Microbial Communities and Organic Matter Composition in Surface and Subsurface Sediments of the Helgoland Mud Area, North Sea.

    PubMed

    Oni, Oluwatobi E; Schmidt, Frauke; Miyatake, Tetsuro; Kasten, Sabine; Witt, Matthias; Hinrichs, Kai-Uwe; Friedrich, Michael W

    2015-01-01

    The role of microorganisms in the cycling of sedimentary organic carbon is a crucial one. To better understand relationships between molecular composition of a potentially bioavailable fraction of organic matter and microbial populations, bacterial and archaeal communities were characterized using pyrosequencing-based 16S rRNA gene analysis in surface (top 30 cm) and subsurface/deeper sediments (30-530 cm) of the Helgoland mud area, North Sea. Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) was used to characterize a potentially bioavailable organic matter fraction (hot-water extractable organic matter, WE-OM). Algal polymer-associated microbial populations such as members of the Gammaproteobacteria, Bacteroidetes, and Verrucomicrobia were dominant in surface sediments while members of the Chloroflexi (Dehalococcoidales and candidate order GIF9) and Miscellaneous Crenarchaeota Groups (MCG), both of which are linked to degradation of more recalcitrant, aromatic compounds and detrital proteins, were dominant in subsurface sediments. Microbial populations dominant in subsurface sediments (Chloroflexi, members of MCG, and Thermoplasmata) showed strong correlations to total organic carbon (TOC) content. Changes of WE-OM with sediment depth reveal molecular transformations from oxygen-rich [high oxygen to carbon (O/C), low hydrogen to carbon (H/C) ratios] aromatic compounds and highly unsaturated compounds toward compounds with lower O/C and higher H/C ratios. The observed molecular changes were most pronounced in organic compounds containing only CHO atoms. Our data thus, highlights classes of sedimentary organic compounds that may serve as microbial energy sources in methanic marine subsurface environments.

  14. Fossilized intact polar lipids of photosynthetic organisms in ancient subsurface sediments

    NASA Astrophysics Data System (ADS)

    Bauersachs, T.; Schouten, S.; Hopmans, E. C.; Sinninghe Damsté, J. S.

    2009-12-01

    In recent years, the idea of a rich microbial biosphere in the marine sea floor has been widely accepted. This so-called “deep biosphere” is estimated to contain ca. 50 % of Earth’s total prokaryotic biomass with the overall order of magnitude of microbial cells in the sea floor being the same as the biomass of all surface plant life (Whitman et al. 1998). Evidence for the existence of a deep biosphere comes, among others, from the analysis of intact polar lipids (IPLs). This approach presumes that IPLs almost instantaneously lose their polar head group after cell death and thus do not preserve on geological timescales. Consequently, IPLs in the subsurface should derive from in situ production and hence indicate the presence of living prokaryotic cells. For example, in various oceanic subsurface sediments archaeal IPLs have been found, suggesting that Archaea constitute a major fraction of the deep biosphere biomass (Lipp et al. 2008). In this study, we found IPLs of heterocystous cyanobacteria in a number of ancient and deeply buried sediments. Heterocystous cyanobacteria are strictly photoautotrophic organisms that are a common constituent of the phytoplankton community in many freshwater and brackish environments but are also encountered in the marine realm as endosymbionts of diatom species. Under nitrogen-depleted conditions, these organisms carry out nitrogen fixation in specialized cells, known as heterocysts. These cells contain a suite of heterocyst glycolipids (HGs) that have not been identified in any other organism and are thus unique biological markers for nitrogen-fixing heterocystous cyanobacteria. Using high performance liquid chromatography coupled to electrospray ionisation tandem mass spectrometry (HPLC/ESI-MS/MS), we detected HGs in Pleistocene and Pliocene Mediterranean sapropels buried up to 60 m below the seafloor. In addition, these HGs were also found in lacustrine deposits of the Oligocene Lake Enspel (35 Ma), the Eocene Lake Messel

  15. Distribution of microbial biomass and potential for anaerobic respiration in Hanford Site 300 Area subsurface sediment.

    PubMed

    Lin, Xueju; Kennedy, David; Peacock, Aaron; McKinley, James; Resch, Charles T; Fredrickson, James; Konopka, Allan

    2012-02-01

    Subsurface sediments were recovered from a 52-m-deep borehole cored in the 300 Area of the Hanford Site in southeastern Washington State to assess the potential for biogeochemical transformation of radionuclide contaminants. Microbial analyses were made on 17 sediment samples traversing multiple geological units: the oxic coarse-grained Hanford formation (9 to 17.4 m), the oxic fine-grained upper Ringold formation (17.7 to 18.1 m), and the reduced Ringold formation (18.3 to 52 m). Microbial biomass (measured as phospholipid fatty acids) ranged from 7 to 974 pmols per g in discrete samples, with the highest numbers found in the Hanford formation. On average, strata below 17.4 m had 13-fold less biomass than those from shallower strata. The nosZ gene that encodes nitrous oxide reductase (measured by quantitative real-time PCR) had an abundance of 5 to 17 relative to that of total 16S rRNA genes below 18.3 m and <5 above 18.1 m. Most nosZ sequences were affiliated with Ochrobactrum anthropi (97 sequence similarity) or had a nearest neighbor of Achromobacter xylosoxidans (90 similarity). Passive multilevel sampling of groundwater geochemistry demonstrated a redox gradient in the 1.5-m region between the Hanford-Ringold formation contact and the Ringold oxic-anoxic interface. Within this zone, copies of the dsrA gene and Geobacteraceae had the highest relative abundance. The majority of dsrA genes detected near the interface were related to Desulfotomaculum spp. These analyses indicate that the region just below the contact between the Hanford and Ringold formations is a zone of active biogeochemical redox cycling. PMID:22138990

  16. Multiple influences of nitrate on uranium solubility during bioremediation of uranium-contaminated subsurface sediments.

    PubMed

    Finneran, Kevin T; Housewright, Meghan E; Lovley, Derek R

    2002-09-01

    Microbiological reduction of soluble U(VI) to insoluble U(IV) has been proposed as a remediation strategy for uranium-contaminated groundwater. Nitrate is a common co-contaminant with uranium. Nitrate inhibited U(VI) reduction in acetate-amended aquifer sediments collected from a uranium-contaminated site in New Mexico. Once nitrate was depleted, both U(VI) and Fe(III) were reduced concurrently. When nitrate was added to sediments in which U(VI) had been reduced, U(VI) reappeared in solution. Parallel studies with the dissimilatory Fe(III)-, U(VI)- and nitrate-reducing microorganism, Geobacter metallireducens, demonstrated that nitrate inhibited reduction of Fe(III) and U(VI) in cell suspensions of cells that had been grown with nitrate as the electron acceptor, but not in Fe(III)-grown cells. Suspensions of nitrate-grown G. metallireducens oxidized Fe(II) and U(IV) with nitrate as the electron acceptor. U(IV) oxidation was accelerated when Fe(II) was also added, presumably due to the Fe(III) being formed abiotically oxidizing U(IV). These studies demonstrate that although the presence of nitrate is not likely to be an impediment to the bioremediation of uranium contamination with microbial U(VI) reduction, it is necessary to reduce nitrate before U(VI) can be reduced. These results also suggest that anaerobic oxidation of U(IV) to U(VI) with nitrate serving as the electron acceptor may provide a novel strategy for solubilizing and extracting microbial U(IV) precipitates from the subsurface.

  17. Studies on arsenic transforming groundwater bacteria and their role in arsenic release from subsurface sediment.

    PubMed

    Sarkar, Angana; Kazy, Sufia K; Sar, Pinaki

    2014-01-01

    Ten different Gram-negative arsenic (As)-resistant and As-transforming bacteria isolated from As-rich groundwater of West Bengal were characterized to assess their role in As mobilization. 16S rRNA gene analysis confirmed the affiliation of these bacteria to genera Achromobacter, Brevundimonas, Rhizobium, Ochrobactrum, and Pseudoxanthomonas. Along with superior As-resistance and As-transformation abilities, the isolates showed broad metabolic capacity in terms of utilizing a variety of electron donors and acceptors (including As) under aerobic and anaerobic conditions, respectively. Arsenic transformation studies performed under various conditions indicated highly efficient As(3+) oxidation or As(5+) reduction kinetics. Genes encoding As(3+) oxidase (aioA), cytosolic As(5+) reductase (arsC), and As(3+) efflux pump (arsB and acr3) were detected within the test isolates. Sequence analyses suggested that As homeostasis genes (particularly arsC, arsB, and acr3) were acquired by most of the bacteria through horizontal gene transfer. A strong correlation between As resistance phenotype and the presence of As(3+) transporter genes was observed. Microcosm study showed that bacterial strain having cytosolic As(5+) reductase property could play important role in mobilizing As (as As(3+)) from subsurface sediment. PMID:24764001

  18. Biogeochemical Coupling of Fe and Tc Speciation in Subsurface Sediments: Implications to Long-Term Tc Immobilization

    SciTech Connect

    Jim K. Fredrickson; C. I. Steefel; R. K. Kukkadapu; S. M. Heald

    2006-06-01

    The project has been focused on biochemical processes in subsurface sediments involving Fe that control the valence state, solubility, and effective mobility of 99Tc. Our goal has been to understand the Tc biogeochemistry as it may occur in suboxic and biostimulated subsurface environments. Two objectives have been pursued: (1) To determine the relative reaction rates of 99Tc(VII)O2(aq) with metal reducing bacteria and biogenic Fe(II); and to characterize the identity, structure, and molecular speciation of Tc(IV) products formed through reaction with both biotic and abiotic reductants. (2) To quantify the biogeochemical factors controlling the reaction rate of O2 with Tc(IV)O2?nH2O in sediment resulting from the direct enzymatic reduction of Tc(VII) by DIRB and/or the reaction of Tc(VII) with the various types of biogenic Fe(II) produced by DIRB.

  19. Archaea in Organic-Lean and Organic-Rich Marine Subsurface Sediments: An Environmental Gradient Reflected in Distinct Phylogenetic Lineages

    PubMed Central

    Durbin, Alan M.; Teske, Andreas

    2012-01-01

    Examining the patterns of archaeal diversity in little-explored organic-lean marine subsurface sediments presents an opportunity to study the association of phylogenetic affiliation and habitat preference in uncultured marine Archaea. Here we have compiled and re-analyzed published archaeal 16S rRNA clone library datasets across a spectrum of sediment trophic states characterized by a wide range of terminal electron-accepting processes. Our results show that organic-lean marine sediments in deep marine basins and oligotrophic open ocean locations are inhabited by distinct lineages of archaea that are not found in the more frequently studied, organic-rich continental margin sediments. We hypothesize that different combinations of electron donor and acceptor concentrations along the organic-rich/organic-lean spectrum result in distinct archaeal communities, and propose an integrated classification of habitat characteristics and archaeal community structure. PMID:22666218

  20. Impact of paleoclimate on the distribution of microbial communities in the subsurface sediment of the Dead Sea.

    PubMed

    Thomas, C; Ionescu, D; Ariztegui, D

    2015-11-01

    A long sedimentary core has been recently retrieved from the Dead Sea Basin (DSB) within the framework of the ICDP-sponsored Dead Sea Deep Drilling Project. Contrasting climatic intervals were evident by distinctive lithological facies such as laminated aragonitic muds and evaporites. A geomicrobiological investigation was conducted in representative sediments of this core. To identify the microbial assemblages present in the sediments and their evolution with changing depositional environments through time, the diversity of the 16S rRNA gene was analyzed in gypsum, aragonitic laminae, and halite samples. The subsurface microbial community was largely dominated by the Euryarchaeota phylum (Archaea). Within the latter, Halobacteriaceae members were ubiquitous, probably favored by their 'high salt-in' osmotic adaptation which also makes them one of the rare inhabitants of the modern Dead Sea. Bacterial community members were scarce, emphasizing that the 'low salt-in' strategy is less suitable in this environment. Substantial differences in assemblages are observed between aragonitic sediments and gypsum-halite ones, independently of the depth and salinity. The aragonite sample, deposited during humid periods when the lake was stratified, consists mostly of the archaeal MSBL1 and bacterial KB1 Candidate Divisions. This consortium probably relies on compatible solutes supplied from the lake by halotolerant species present in these more favorable periods. In contrast, members of the Halobacteriaceae were the sole habitants of the gypsum-halite sediments which result from a holomictic lake. Although the biomass is low, these variations in the observed subsurface microbial populations appear to be controlled by biological conditions in the water column at the time of sedimentation, and subsequently by the presence or absence of stratification and dilution in the lake. As the latter are controlled by climatic changes, our data suggest a relationship between local

  1. Impact of paleoclimate on the distribution of microbial communities in the subsurface sediment of the Dead Sea.

    PubMed

    Thomas, C; Ionescu, D; Ariztegui, D

    2015-11-01

    A long sedimentary core has been recently retrieved from the Dead Sea Basin (DSB) within the framework of the ICDP-sponsored Dead Sea Deep Drilling Project. Contrasting climatic intervals were evident by distinctive lithological facies such as laminated aragonitic muds and evaporites. A geomicrobiological investigation was conducted in representative sediments of this core. To identify the microbial assemblages present in the sediments and their evolution with changing depositional environments through time, the diversity of the 16S rRNA gene was analyzed in gypsum, aragonitic laminae, and halite samples. The subsurface microbial community was largely dominated by the Euryarchaeota phylum (Archaea). Within the latter, Halobacteriaceae members were ubiquitous, probably favored by their 'high salt-in' osmotic adaptation which also makes them one of the rare inhabitants of the modern Dead Sea. Bacterial community members were scarce, emphasizing that the 'low salt-in' strategy is less suitable in this environment. Substantial differences in assemblages are observed between aragonitic sediments and gypsum-halite ones, independently of the depth and salinity. The aragonite sample, deposited during humid periods when the lake was stratified, consists mostly of the archaeal MSBL1 and bacterial KB1 Candidate Divisions. This consortium probably relies on compatible solutes supplied from the lake by halotolerant species present in these more favorable periods. In contrast, members of the Halobacteriaceae were the sole habitants of the gypsum-halite sediments which result from a holomictic lake. Although the biomass is low, these variations in the observed subsurface microbial populations appear to be controlled by biological conditions in the water column at the time of sedimentation, and subsequently by the presence or absence of stratification and dilution in the lake. As the latter are controlled by climatic changes, our data suggest a relationship between local

  2. Isolation and Characterization of Gram-Positive Piezophilic Bacteria from Deep Marine Subsurface Sediment

    NASA Astrophysics Data System (ADS)

    Runko, G. M.; Fang, J.; Kato, C.

    2014-12-01

    The marine deep biosphere remains as the least studied of all of Earth's habitats and is inadequately understood, but is extremely important to understand the impacts that microbes have on global biogeochemical cycles. Sediment samples were obtained during IODP Expedition 337 in the western Pacific Ocean, from 1,498 meters below the seafloor (mbsf; samples 6R3), 1,951-1,999 mbsf (19R1), and 2,406 mbsf (29R7). These samples were initially mixed with marine broth and cultivated under anaerobic conditions at pressure of 35 MPa (megapascal) and temperatures of 35° C, 45° C, and 55° C for 3 months on board the Chikyu. Single colonies were isolated via plating on marine broth. Then, six strains of bacteria were identified, 6R3-1, 6R3-15, 19R1-5, 29R7-12B, 29R7-12M, and 29R7-12S. The six strains were then examined for optimal growth temperature and pressure. These organisms are Gram-positive, spore-forming, facultative anaerobic piezophilic bacteria. Major fatty acids are anteiso-15:0, anteiso-17:0 and iso-15:0. Phylogenetic analysis of 16S rRNA gene sequences revealed that the isolates are closely related to Virgibacillus pantothenticus, Robinsoniella peoriensis, and Bacillus subtilis. Because of their abundance in the deep marine subsurface, these microorganisms likely play an important role in sustaining the deep microbial ecosystem and influencing biogeochemical cycles in the deep biosphere.

  3. Characterization of the intragranular water regime within subsurface sediments: Pore volume, surface area, and mass transfer limitations

    USGS Publications Warehouse

    Hay, M.B.; Stoliker, D.L.; Davis, J.A.; Zachara, J.M.

    2011-01-01

    Although "intragranular" pore space within grain aggregates, grain fractures, and mineral surface coatings may contain a relatively small fraction of the total porosity within a porous medium, it often contains a significant fraction of the reactive surface area, and can thus strongly affect the transport of sorbing solutes. In this work, we demonstrate a batch experiment procedure using tritiated water as a high-resolution diffusive tracer to characterize the intragranular pore space. The method was tested using uranium-contaminated sediments from the vadose and capillary fringe zones beneath the former 300A process ponds at the Hanford site (Washington). Sediments were contacted with tracers in artificial groundwater, followed by a replacement of bulk solution with tracer-free groundwater and the monitoring of tracer release. From these data, intragranular pore volumes were calculated and mass transfer rates were quantified using a multirate first-order mass transfer model. Tritium-hydrogen exchange on surface hydroxyls was accounted for by conducting additional tracer experiments on sediment that was vacuum dried after reaction. The complementary ("wet" and "dry") techniques allowed for the simultaneous determination of intragranular porosity and surface area using tritium. The Hanford 300A samples exhibited intragranular pore volumes of ???1% of the solid volume and intragranular surface areas of ???20%-35% of the total surface area. Analogous experiments using bromide ion as a tracer yielded very different results, suggesting very little penetration of bromide into the intragranular porosity. Copyright 2011 by the American Geophysical Union.

  4. Characterization of the intragranular water regime within subsurface sediments: pore volume, surface area, and mass transfer limitations

    USGS Publications Warehouse

    Hay, Michael B.; Stoliker, Deborah L.; Davis, James A.; Zachara, John M.

    2011-01-01

    Although "intragranular" pore space within grain aggregates, grain fractures, and mineral surface coatings may contain a relatively small fraction of the total porosity within a porous medium, it often contains a significant fraction of the reactive surface area, and can thus strongly affect the transport of sorbing solutes. In this work, we demonstrate a batch experiment procedure using tritiated water as a high-resolution diffusive tracer to characterize the intragranular pore space. The method was tested using uranium-contaminated sediments from the vadose and capillary fringe zones beneath the former 300A process ponds at the Hanford site (Washington). Sediments were contacted with tracers in artificial groundwater, followed by a replacement of bulk solution with tracer-free groundwater and the monitoring of tracer release. From these data, intragranular pore volumes were calculated and mass transfer rates were quantified using a multirate first-order mass transfer model. Tritium-hydrogen exchange on surface hydroxyls was accounted for by conducting additional tracer experiments on sediment that was vacuum dried after reaction. The complementary ("wet" and "dry") techniques allowed for the simultaneous determination of intragranular porosity and surface area using tritium. The Hanford 300A samples exhibited intragranular pore volumes of ~1% of the solid volume and intragranular surface areas of ~20%–35% of the total surface area. Analogous experiments using bromide ion as a tracer yielded very different results, suggesting very little penetration of bromide into the intragranular porosity.

  5. Characterization of the intragranular water regime within subsurface sediments: Pore volume, surface area, and mass transfer limitations

    NASA Astrophysics Data System (ADS)

    Hay, Michael B.; Stoliker, Deborah L.; Davis, James A.; Zachara, John M.

    2011-10-01

    Although "intragranular" pore space within grain aggregates, grain fractures, and mineral surface coatings may contain a relatively small fraction of the total porosity within a porous medium, it often contains a significant fraction of the reactive surface area, and can thus strongly affect the transport of sorbing solutes. In this work, we demonstrate a batch experiment procedure using tritiated water as a high-resolution diffusive tracer to characterize the intragranular pore space. The method was tested using uranium-contaminated sediments from the vadose and capillary fringe zones beneath the former 300A process ponds at the Hanford site (Washington). Sediments were contacted with tracers in artificial groundwater, followed by a replacement of bulk solution with tracer-free groundwater and the monitoring of tracer release. From these data, intragranular pore volumes were calculated and mass transfer rates were quantified using a multirate first-order mass transfer model. Tritium-hydrogen exchange on surface hydroxyls was accounted for by conducting additional tracer experiments on sediment that was vacuum dried after reaction. The complementary ("wet" and "dry") techniques allowed for the simultaneous determination of intragranular porosity and surface area using tritium. The Hanford 300A samples exhibited intragranular pore volumes of ˜1% of the solid volume and intragranular surface areas of ˜20%-35% of the total surface area. Analogous experiments using bromide ion as a tracer yielded very different results, suggesting very little penetration of bromide into the intragranular porosity.

  6. Isotopic identification of the source of methane in subsurface sediments of an area surrounded by waste disposal facilities

    USGS Publications Warehouse

    Hackley, Keith C.; Liu, Chao-Li; Trainor, D.

    1999-01-01

    The major source of methane (CH4) in subsurface sediments on the property of a former hazardous waste treatment facility was determined using isotopic analyses measured on CH4 and associated groundwater. The site, located on an earthen pier built into a shallow wetland lake, has had a history of waste disposal practices and is surrounded by landfills and other waste management facilities. Concentrations of CH4 up to 70% were found in the headspace gases of several piezometers screened at 3 different depths (ranging from 8 to 17 m) in lacustrine and glacial till deposits. Possible sources of the CH4 included a nearby landfill, organic wastes from previous impoundments and microbial gas derived from natural organic matter in the sediments. Isotopic analyses included ??13C, ??D, 14C, and 3H on select CH4 samples and ??D and ??18O on groundwater samples. Methane from the deepest glacial till and intermediate lacustrine deposits had ??13C values from -79 to -82???, typical of natural 'drift gas' generated by microbial CO2-reduction. The CH4 from the shallow lacustrine deposits had ??13C values from -63 to -76???, interpreted as a mixture between CH4 generated by microbial fermentation and the CO2-reduction processes within the subsurface sediments. The ??D values of all the CH4 samples were quite negative ranging from -272 to -299???. Groundwater sampled from the deeper zones also showed quite negative ??D values that explained the light ??D observed for the CH4. Radiocarbon analyses of the CH4 showed decreasing 14C activity with depth, from a high of 58 pMC in the shallow sediments to 2 pMC in the deeper glacial till. The isotopic data indicated the majority of CH4 detected in the fill deposits of this site was microbial CH4 generated from naturally buried organic matter within the subsurface sediments. However, the isotopic data of CH4 from the shallow piezometers was more variable and the possibility of some mixing with oxidized landfill CH4 could not be completely

  7. PROTOZOA IN SUBSURFACE SEDIMENTS FROM SITE CONTAMI- NATED WITH AVIATION GASOLINE OR JET FUEL

    EPA Science Inventory

    Numbers of protozoa in the subsurface of aviation gasoline and jet fuel spill areas at a Coast Guard base at Traverse City, Mich., were determined. Boreholes were drilled in an uncontaminated location, in contaminated but untreated parts of the fuel plumes, and in the aviation ga...

  8. Morphologic evidence of subsurface sediment mobilization and mud volcanism in Candor and Coprates Chasmata, Valles Marineris, Mars

    NASA Astrophysics Data System (ADS)

    Okubo, Chris H.

    2016-05-01

    Populations of distinctive knobs, rings and lobate structures are observed in the Candor and Coprates Chasmata regions of Mars. To interpret the formation mechanisms of these landforms, I investigate their morphologies, facies, superposition and crosscutting relationships using data from the High Resolution Imaging Science Experiment (HiRISE) and the High Resolution Stereo Camera (HRSC). The knobs and rings have quasi-circular to elliptical shapes in map view, with basal diameters between several hundred meters and three kilometers. The knobs rise ∼10 to 350 m above the surrounding terrain, while the rings are ∼10 to 70 m tall. In three dimensions the knobs have a rounded cone shape, and some knobs exhibit a summit depression, which in some examples contains a subordinate mound. The rings have rounded to sharp crests and in some instances contain subordinate rings and mounds. The lobate structures are commonly ∼1 to 2 km wide, ∼3 to 5 km long and rise up to 50 m above the surrounding terrain. The lobate structures partially or completely encircle some knobs, rings and irregularly shaped rock masses. The knobs, rings and lobate structures exhibit massive and stratified facies, with some structures exhibiting both, such as a massive central rock mass surrounded by outwardly dipping layers. I interpret these landforms as mud volcanoes, injectites and mud flows based on superposition and cross-cutting relationships as well as similarities between the morphologies and facies of these landforms with terrestrial products of mud volcanism. I infer the source of sediment for this mud volcanism to be the Hesperian eolian deposits that occur within these chasmata. Further, I suggest that groundwater upwelling during the Hesperian to possibly the Early Amazonian facilitated the mobilization of these sediments within the subsurface and thereby contributed to the ensuing mud volcanism. Based on these results, I propose that the Candor Chaos formed through subsurface

  9. Isolation and microbial reduction of Fe(III) phyllosilicates from subsurface sediments

    SciTech Connect

    Wu, Tao; Shelobolina, Evgenya S.; Xu, Huifang; Konishi, Hiromi; Kukkadapu, Ravi K.; Roden, Eric E.

    2012-10-12

    Fe(III)-bearing phyllosilicates can be important sources of Fe(III) for dissimilatory microbial iron reduction in clay-rich anoxic soils and sediments. The goal of this research was to isolate Fe(III) phyllosilicate phases, and if possible, Fe(III) oxide phases, from a weathered shale saprolite sediment in order to permit experimentation with each phase in isolation. Physical partitioning by density gradient centrifugation did not adequately separate phyllosilicate and Fe(III) oxide phases (primarily nanoparticulate goethite). Hence we examined the ability of chemical extraction methods to remove Fe(III) oxides without significantly altering the properties of the phyllosilicates. XRD analysis showed that extraction with oxalate alone or oxalate in the presence of added Fe(II) altered the structure of Fe-bearing phyllosilicates in the saprolite. In contrast, citrate-bicarbonate-dithionite (CBD) extraction at room temperature and 80C led to minimal alteration of phyllosilicate structures. Reoxidation of CDB-extracted sediment with H2O2 restored phyllosilicate structure (i.e. d-spacing) and redox speciation to conditions similar to that in the pristine sediment. The extent of microbial (Geobacter sulfurreducens) reduction of Fe(III) phyllosilicates isolated by CDB extraction (ca. 16 %) was comparable to what took place in pristine sediments as determined by Mossbauer spectroscopy (ca. 18 % reduction). These results suggest that materials isolated by CDB extraction and H2O2 reoxidation are appropriate targets for detailed studies of natural soil/sediment Fe(III) phyllosilicate reduction.

  10. Degradation of the herbicide dichlobenil and its metabolite BAM in soils and subsurface sediments.

    PubMed

    Clausen, Liselotte; Arildskov, Niels P; Larsen, Flemming; Aamand, Jens; Albrechtsen, Hans-Jørgen

    2007-01-30

    The worldwide used herbicide dichlobenil (2,6-dichlorobenzonitrile) has resulted in widespread presence of its metabolite 2,6-dichlorobenzamide (BAM) in surface water and groundwater. To evaluate the potential for natural attenuation of this BAM pollution in groundwater, we studied the degradation of BAM and dichlobenil in 16 samples of clayey till, unconsolidated sand and limestone, including sediments from both oxidized and reduced conditions. The degradation of dichlobenil occurred primarily in the upper few meters below surface, although dichlobenil was strongly sorbed to these sediments. However, the degradation of dichlobenil to BAM could not be correlated to either sorption, water chemistry, composition of soils or sediments. Degradation of dichlobenil to BAM was limited (<2% degraded) in the deeper unsaturated zones, and no degradation was observed in aquifer sediments. This illustrates, that dichlobenil transported to aquifers does not contribute to the BAM-contamination in aquifers. A small, but significant degradation of BAM was observed in the upper part of the unsaturated zones in sandy sediments, but no degradation was observed in the clayey till sediment or in the deeper unsaturated zones. The insignificant degradation of BAM in aquifer systems shows that BAM pollution detected in aquifers will appear for a long time; and consequently the potential for natural attenuation of BAM in aquifer systems is limited.

  11. HyFlux - Part II: Subsurface sequestration of methane-derived carbon in gas-hydrate- bearing marine sediments

    NASA Astrophysics Data System (ADS)

    Naehr, T. H.; Asper, V. L.; Garcia, O.; Kastner, M.; Leifer, I.; MacDonald, I. R.; Solomon, E. A.; Yvon-Lewis, S.; Zimmer, B.

    2008-12-01

    The recently funded DOE/NETL study "HyFlux: Remote sensing and sea-truth measurements of methane flux to the atmosphere" (see MacDonald et al.: HyFlux - Part I) will combine sea surface, water column and shallow subsurface observations to improve our estimates of methane flux from submarine seeps and associated gas hydrate deposits to the water column and atmosphere along the Gulf of Mexico continental margin and other selected areas world-wide. As methane-rich fluids rise towards the sediment-water interface, they will interact with sulfate-rich pore fluids derived from overlying bottom water, which results in the formation of an important biogeochemical redox boundary, the so-called sulfate-methane interface, or SMI. Both methane and sulfate are consumed within the SMI and dissolved inorganic carbon, mostly bicarbonate (HCO3-) and hydrogen sulfide are produced, stimulating authigenic carbonate precipitation at and immediately below the SMI. Accordingly, the formation of authigenic carbonates in methane- and gas-hydrate-rich sediments will sequester a portion of the methane-derived carbon. To date, however, little is known about the quantitative aspects of these reactions. Rates of DIC production are not well constrained, but recent biogeochemical models indicate that CaCO3 precipitation rates may be as high as 120 μmol cm-2a-1. Therefore, AOM-driven carbonate precipitation must be considered when assessing the impact of gas-hydrate-derived methane on the global carbon cycle. As part of HyFlux, we will conduct pore water analyses (DOC, DIC, CH4, δ13CDIC, δ13CDOC, δ13CCH4, δ18O, and δD isotope ratios) to evaluate the importance of authigenic carbonate precipitation as a sequestration mechanism for methane- derived carbon. In addition, sediment and seafloor carbonate samples will be analyzed for bulk sedimentary carbonate (δ13C and δ18O) and bulk sedimentary organic matter (δ13C and δ15N), as well as sulfur, bulk mineralogy, texture and morphological

  12. A simulation study of infiltration into surficial sediments at the Subsurface Disposal Area, Idaho National Engineering Laboratory

    SciTech Connect

    Martian, P.; Magnuson, S.O.

    1994-04-01

    Soil moisture monitoring data in the surficial sediments at the Subsurface Disposal Area (SDA) at the Idaho National Engineering Laboratory were used to calibrate two numerical infiltration models. The calibration was performed with the ultimate goal of providing a reliable estimate of hydraulic properties and infiltration amounts to be used in other modeling efforts. Two neutron probe access tubes and a tensiometer nest were monitored from 1986 to 1990 and again during 1993. The field measurements of moisture content and matrix potential inside the SDA were used as calibration data for the two locations. The two locations showed vastly different behavior, which was well captured in the models. The average root mean square error between simulated and measured moisture contents over the simulation period was 0.03 and 0.06 for the two locations. The hydraulic parameters resulting from the calibration compared favorably with laboratory and field scale estimates. The simulation results also provided the opportunity to partially explain infiltration and redistribution processes occurring at the SDA. The underlying fractured basalt appears to behave similar to a capillary barrier. This behavior inhibits moisture movement into the underlying basalts until moisture contents in the overlying silts approach saturation. As a result, a large proportion of recharge occurring at the SDA may be due to spring snowmelt, when the surficial sediments become nearly saturated. The results also indicated that a unit gradient boundary condition (free drainage due to gravity) at the bottom of the silts is not appropriate because of the very low relative hydraulic conductivity of the basalts. Finally, the amount of water moving into the SDA subsurface from spring snowmelt appears larger than cumulative snowfall, indicating that snow drifting due to local topography as well as current snow management practices may have a substantial influence on local infiltration.

  13. Geochemical and microbiological responses to oxidant introduction into reduced subsurface sediment from the Hanford 300 Area, Washington.

    PubMed

    Percak-Dennett, Elizabeth M; Roden, Eric E

    2014-08-19

    Pliocene-aged reduced lacustrine sediment from below a subsurface redox transition zone at the 300 Area of the Hanford site (southeastern Washington) was used in a study of the geochemical response to introduction of oxygen or nitrate in the presence or absence of microbial activity. The sediments contained large quantities of reduced Fe in the form of Fe(II)-bearing phyllosilicates, together with smaller quantities of siderite and pyrite. A loss of ca. 50% of 0.5 M HCl-extractable Fe(II) [5-10 mmol Fe(II) L(-1)] and detectable generation of sulfate (ca. 0.2 mM, equivalent to 10% of the reduced inorganic sulfur pool) occurred in sterile aerobic reactors. In contrast, no systematic loss of Fe(II) or production of sulfate was observed in any of the other oxidant-amended sediment suspensions. Detectable Fe(II) accumulation and sulfate consumption occurred in non-sterile oxidant-free reactors. Together, these results indicate the potential for heterotrophic carbon metabolism in the reduced sediments, consistent with the proliferation of known heterotrophic taxa (e.g., Pseudomonadaceae, Burkholderiaceae, and Clostridiaceae) inferred from 16S rRNA gene pyrosequencing. Microbial carbon oxidation by heterotrophic communities is likely to play an important role in maintaining the redox boundary in situ, i.e., by modulating the impact of downward oxidant transport on Fe/S redox speciation. Diffusion-reaction simulations of oxygen and nitrate consumption coupled to solid-phase organic carbon oxidation indicate that heterotrophic consumption of oxidants could maintain the redox boundary at its current position over millennial time scales. PMID:25014732

  14. Aminostratigraphy of surface and subsurface Quaternary sediments, North Carolina coastal plain, USA

    USGS Publications Warehouse

    Wehmiller, J. F.; Thieler, E.R.; Miller, D.; Pellerito, V.; Bakeman, Keeney V.; Riggs, S.R.; Culver, S.; Mallinson, D.; Farrell, K.M.; York, L.L.; Pierson, J.; Parham, P.R.

    2010-01-01

    The Quaternary stratigraphy and geochronology of the Albemarle Embayment of the North Carolina (NC) Coastal Plain is examined using amino acid racemization (AAR) in marine mollusks, in combination with geophysical, lithologic, and biostratigraphic analysis of 28 rotasonic cores drilled between 2002 and 2006. The Albemarle Embayment is bounded by structural highs to the north and south, and Quaternary strata thin westward toward the Suffolk paleoshoreline, frequently referred to as the Suffolk Scarp. The Quaternary section is up to ???90. m thick, consists of a variety of estuarine, shelf, back-barrier, and lagoonal deposits, and has been influenced by multiple sea-level cycles. The temporal resolution of the amino acid racemization method is tested statistically and with the stratigraphic control provided by this geologic framework, and it is then applied to the correlation and age estimation of subsurface units throughout the region. Over 500 specimens (primarily Mercenaria and Mulinia) from the subsurface section have been analyzed using either gas chromatographic (GC) or reverse-phase liquid chromatographic (RPLC) techniques. The subsurface stratigraphic data are compared with AAR results from numerous natural or excavated exposures from the surrounding region, as well as results from NC beach collections, to develop a comprehensive aminostratigraphic database for the entire Quaternary record within the NC coastal system. Age mixing, recognized in the beach collections, is also seen in subsurface sections, usually where major seismic reflections or core lithology indicate the presence of stratigraphic discontinuities. Kinetic models for racemization are tested within the regional stratigraphic framework, using either radiocarbon or U-series calibrations or comparison with regional biostratigraphy. Three major Pleistocene aminozones [AZ2, AZ3, and AZ4] are found throughout the region, all being found in superposition in several cores. Each can be subdivided

  15. Spatial and temporal variations of microbial properties at different scales in shallow subsurface sediments

    SciTech Connect

    Zhang, Chuanlun; Pfiffner, S.M.; Phelps, T.J.

    1997-12-31

    Microbial abundance, activity, and community-level physiological profiles (CLPP) were examined at centimeter and meter scales in the subsurface environment at a site near Oyster, VA. At the centimeter scale, variations in aerobic culturable heterotrophs (ACH) and glucose mineralization rates (GMR) were highest in the water table zone, indicating that water availability has a major effect on variations in microbial abundance and activity. At the meter scale, ACH and microaerophiles decreased significantly with depth, whereas anaerobic GMR often increased with depth; this may indicate low redox potentials at depth caused by microbial consumption of oxygen. Data of CUP indicated that the microbial community (MC) in the soybean field exhibited greater capability to utilize multiple carbon sources than MC in the corn field. This difference may reflect nutrient availability associated with different crops (soybean vs corn). By using a regression model, significant spatial and temporal variations were observed for ACH, microaerophiles, anaerobic GMR, and CLPP. Results of this study indicated that water and nutrient availability as well as land use could have a dominant effect on spatial and temporal variations in microbial properties in shallow subsurface environments. 32 refs., 3 figs., 3 tabs.

  16. Feasibility of In Situ Redox Manipulation of Subsurface Sediments for RDX Remediation at Pantex

    SciTech Connect

    Szecsody, James E.; Fruchter, Jonathan S.; Mckinley, Mark A.; Resch, Charles T.; Gilmore, Tyler J.

    2001-12-31

    This laboratory study was conducted to assess RDX (hexahydro-1,3,5-trinitro-1,3,5 triazine) abiotic degradation by chemically reduced sediments and other geochemical aspects of the application of this technology to remediation of RDX contamination in groundwater at the U.S. DOE Pantex facility...

  17. Controls on subsurface methane fluxes and shallow gas formation in Baltic Sea sediment (Aarhus Bay, Denmark)

    NASA Astrophysics Data System (ADS)

    Flury, Sabine; Røy, Hans; Dale, Andrew W.; Fossing, Henrik; Tóth, Zsuzsanna; Spiess, Volkhard; Jensen, Jørn Bo; Jørgensen, Bo Barker

    2016-09-01

    Shallow gas accumulates in coastal marine sediments when the burial rate of reactive organic matter beneath the sulfate zone is sufficiently high and the methanogenic zone is sufficiently deep. We investigated the controls on methane production and free methane gas accumulation along a 400 m seismo-acoustic transect across a sharp transition from gas-free into gas-bearing sediment in Aarhus Bay (Denmark). Twelve gravity cores were taken, in which the pore water was analyzed for inorganic solutes while rates of organic carbon mineralization were measured experimentally by 35SO42- radiotracer method. The thickness of organic-rich Holocene mud increased from 5 to 10 m along the transect concomitant with a shallowing of the depth of the sulfate-methane transition from >4 m to 2.5 m. In spite of drastic differences in the distribution of methane and sulfate in the sediment along the transect, there were only small differences in total mineralization, and methanogenesis was only equivalent to about 1% of sulfate reduction. Shallow gas appeared where the mud thickness exceeded 8-9 m. Rates of methanogenesis increased along the transect as did the upward diffusive flux of methane. Interestingly, the increase in the sedimentation rate and Holocene mud thickness had only a modest direct effect on methanogenesis rates in deep sediments. This increase in methane flux, however, triggered a shallowing of the sulfate-methane transition which resulted in a large increase in methanogenesis at the top of the methanogenic zone. Thus, our results demonstrate a positive feedback mechanism that causes a strong enhancement of methanogenesis and explains the apparently abrupt appearance of gas when a threshold thickness of organic-rich mud is exceeded.

  18. Oxidative Dissolution Potential of Biogenic and Abiogenic TcO2 in Subsurface Sediments

    SciTech Connect

    Fredrickson, Jim K.; Zachara, John M.; Plymale, Andrew E.; Heald, Steve M.; McKinley, James P.; Kennedy, David W.; Liu, Chongxuan; Nachimuthu, Ponnusamy

    2009-04-15

    Technetium-99 (Tc) is an important fission product contaminant associated with sites of nuclear fuels reprocessing and geologic nuclear waste disposal. Exhibiting an intermediate redox potential, Tc is highly mobile in its anionic, oxidized state [Tc(VII)O4-]; and less mobile as a poorly soluble oxyhydroxide precipitate [Tc(IV)O2•nH2O] in its reduced state. Here we investigate the potential for oxidation of Tc(IV) that was heterogeneously reduced by reaction with biogenic Fe(II) in two sediments differing in mineralogy and aggregation state (FRC, RG). Both sediments contained Fe(III) and Mn(III/IV) as redox active phases, but FRC also contained mass-dominant Fe-phyllosilicates of different types. Biogenic Tc(IV)O2•nH2O was oxidized in anoxic, but unreduced RG and FRC sediments through redox interaction with Mn(III/IV) oxides. Bioreduction by Shewanella putrefaciens CN32 dissolved Mn(III/IV) oxides and generated biogenic Fe(II) that was reactive with Tc(VII) in heat-killed, bioreduced sediment. Biogenic Fe(II) in the FRC exceeded that in RG by a factor of two. More rapid reduction rates were observed in the RG that had lower biogenic Fe(II), and less particle aggregation. EXAFS measurements indicated that the primary reduction product was a TcO2-like phase in both sediments. Redox product Tc(IV) oxidized rapidly and completely in RG when contacted with air. Oxidation, in contrast, was slow and incomplete in the FRC, in spite of similar molecular speciation to RG. X-ray microprobe, electron microprobe, x-ray absorption spectroscopy, and micro x-ray diffraction were applied to the whole sediment and isolated Tc-contained particles. These analyses revealed that non-oxidizable Tc(IV) in the FRC existed as complexes with octahedral Fe(III) within intra-grain domains of 50-100 µm-sized, Fe-containing micas presumptively identified as celadonite. The markedly slower oxidation rates in FRC as compared to RG were attributed to mass-transfer-limited migration of O2 into

  19. Protozoa in subsurface sediments from sites contaminated with aviation gasoline or jet fuel

    SciTech Connect

    Sinclair, J.L.; Kampbell, D.H.; Cook, M.L.; Wilson, J.T.

    1993-01-01

    Numbers of protozoa in the subsurface of aviation gasoline and jet fuel spill areas at a Coast Guard base at Traverse City, Mich., were determined. Boreholes were drilled in an uncontaminated location, in contaminated but untreated parts of the fuel plumes, and in the aviation gasoline source area undergoing H2O2 biotreatment. Protozoa were found to occur in elevated numbers in the unsaturated zone, where fuel vapors mixed with atmospheric oxygen, and below the layer of floating fuel, where uncontaminated groundwater came into contact with fuel. Numbers of protozoa in some contaminated areas equalled or exceeded those found in surface soil. The abundance of protozoa in the biotreatment area was high enough that it would be expected to significantly reduce the bacterial community that was degrading the fuel.

  20. Residence of habitat-specific anammox bacteria in the deep-sea subsurface sediments of the South China Sea: analyses of marker gene abundance with physical chemical parameters.

    PubMed

    Hong, Yi-Guo; Li, Meng; Cao, Huiluo; Gu, Ji-Dong

    2011-07-01

    Anaerobic ammonium oxidation (anammox) has been recognized as an important process for the global nitrogen cycle. In this study, the occurrence and diversity of anammox bacteria in the deep-sea subsurface sediments of the South China Sea (SCS) were investigated. Results indicated that the anammox bacterial sequences recovered from this habitat by amplifying both 16S rRNA gene and hydrazine oxidoreductase encoding hzo gene were all closely related to the Candidatus Scalindua genus. A total of 96 16S rRNA gene sequences from 346 clones were grouped into five subclusters: two subclusters affiliated with the brodae and arabica species, while three new subclusters named zhenghei-I, -II, and -III showed ≤ 97.4% nucleic acid sequence identity with other known Candidatus Scalindua species. Meanwhile, 88 hzo gene sequences from the sediments also formed five distant subclusters within hzo cluster 1c. Through fluorescent real-time PCR analysis, the abundance of anammox bacteria in deep-sea subsurface sediment was quantified by hzo genes, which ranged from 1.19 × 10(4) to 7.17 × 10(4) copies per gram of dry sediments. Combining all the information from this study, diverse Candidatus Scalindua anammox bacteria were found in the deep-sea subsurface sediments of the SCS, and they could be involved in the nitrogen loss from the fixed inventory in the habitat.

  1. Discriminative detection and enumeration of microbial life in marine subsurface sediments.

    PubMed

    Morono, Yuki; Terada, Takeshi; Masui, Noriaki; Inagaki, Fumio

    2009-05-01

    Detection and enumeration of microbial life in natural environments provide fundamental information about the extent of the biosphere on Earth. However, it has long been difficult to evaluate the abundance of microbial cells in sedimentary habitats because non-specific binding of fluorescent dye and/or auto-fluorescence from sediment particles strongly hampers the recognition of cell-derived signals. Here, we show a highly efficient and discriminative detection and enumeration technique for microbial cells in sediments using hydrofluoric acid (HF) treatment and automated fluorescent image analysis. Washing of sediment slurries with HF significantly reduced non-biological fluorescent signals such as amorphous silica and enhanced the efficiency of cell detachment from the particles. We found that cell-derived SYBR Green I signals can be distinguished from non-biological backgrounds by dividing green fluorescence (band-pass filter: 528/38 nm (center-wavelength/bandwidth)) by red (617/73 nm) per image. A newly developed automated microscope system could take a wide range of high-resolution image in a short time, and subsequently enumerate the accurate number of cell-derived signals by the calculation of green to red fluorescence signals per image. Using our technique, we evaluated the microbial population in deep marine sediments offshore Peru and Japan down to 365 m below the seafloor, which provided objective digital images as evidence for the quantification of the prevailing microbial life. Our method is hence useful to explore the extent of sub-seafloor life in the future scientific drilling, and moreover widely applicable in the study of microbial ecology.

  2. Discriminative detection and enumeration of microbial life in marine subsurface sediments.

    PubMed

    Morono, Yuki; Terada, Takeshi; Masui, Noriaki; Inagaki, Fumio

    2009-05-01

    Detection and enumeration of microbial life in natural environments provide fundamental information about the extent of the biosphere on Earth. However, it has long been difficult to evaluate the abundance of microbial cells in sedimentary habitats because non-specific binding of fluorescent dye and/or auto-fluorescence from sediment particles strongly hampers the recognition of cell-derived signals. Here, we show a highly efficient and discriminative detection and enumeration technique for microbial cells in sediments using hydrofluoric acid (HF) treatment and automated fluorescent image analysis. Washing of sediment slurries with HF significantly reduced non-biological fluorescent signals such as amorphous silica and enhanced the efficiency of cell detachment from the particles. We found that cell-derived SYBR Green I signals can be distinguished from non-biological backgrounds by dividing green fluorescence (band-pass filter: 528/38 nm (center-wavelength/bandwidth)) by red (617/73 nm) per image. A newly developed automated microscope system could take a wide range of high-resolution image in a short time, and subsequently enumerate the accurate number of cell-derived signals by the calculation of green to red fluorescence signals per image. Using our technique, we evaluated the microbial population in deep marine sediments offshore Peru and Japan down to 365 m below the seafloor, which provided objective digital images as evidence for the quantification of the prevailing microbial life. Our method is hence useful to explore the extent of sub-seafloor life in the future scientific drilling, and moreover widely applicable in the study of microbial ecology. PMID:19212428

  3. Assessing water quality by ratio of the number of dominant bacterium species between surface/subsurface sediments in Haihe River Basin.

    PubMed

    Ke, Xin; Wang, Chunyong; Jing, Debing; Zhang, Yun; Zhang, Haijun

    2015-09-15

    Sedimentary microorganisms can be used as a sensitive indicator of integrated aquatic environment quality assessment and indicate long-term water quality or toxicity. According to the Chinese National Standards of GB 3838-2002 and GB 18918-2002, the comprehensive water quality in Haihe River Basin has been described. Results showed that the comprehensive water quality in 6 sites, 4 sites, and 20 sites were good, bad, and medium. Furthermore, 162 dominant bacterial species were identified in surface and subsurface sediments in the 30 sampling sites. As revealed by two initial models constructed by logistic regression, the comprehensive water quality exhibited a pattern from good to bad as the ratio of the number of dominant bacterial species in surface sediments to that in subsurface sediments increased from 1 to 2.1. This finding possibly bridged a traditional gap between aquatic microbe indicators and water quality assessment or monitoring techniques.

  4. Impact of Highly Basic Solutions on Sorption of Cs+ to Subsurface Sediments from the Hanford Site, USA

    SciTech Connect

    Ainsworth, Calvin C.; Zachara, John M.; Wagnon, Ken B.; McKinley, Susan G.; Liu, Chongxuan; Smith, Steven C.; Schaef, Herbert T.; Gassman, Paul L.

    2005-11-28

    The effect of caustic NaNO3 solutions on the sorption of 137Cs to the Hanford site micaceous subsurface sediment was investigated as a function of time, temperature (10 C or 50 C), and NaOH concentration. At 100C and 0.1 M NaOH, the slow evolution of [Al]aq was in stack contrast to the rapid increase and subsequent loss of [Al]aq observed at 50 C (regardless of base concentration). At 50 C, dissolution of phyllosilicate minerals increased with [OH], at 1 and 3 M NaOH solutions, almost complete dissolution of clay-sized phyllosilicates occurred. At 0.1 M NaOH, a zeolite (tetranatrolite) precipitated after about 7 days, while an unnamed mineral phase (Na2Al2Si3O10?2H2O) precipitated after 4 and 2 days of exposure to 1 M and 3 M NaOH solutions. At 100C there was no conclusive evidence of secondary mineral precipitation. The effect of base dissolution on Cs+ sorption by the Hanford sediment was investigated via (1) Cs+ sorption over a large concentration range (10-9 ? 10-2 mol/L) to sediment after exposure to 0.1 M NaOH for 56, 112, and 168 days, (2) Cs+ sorption to sediment in the presence of NaOH (0.1 M, 1 M, and 3 M NaOH) at Cs+ concentrations selected to probe high affinity, transition, and low affinity cation exchange sites, and (3) the application of a two-site numeric ion exchange model (Zachara et al. 2002a). No effect on Cs+ sorption to the Hanford sediment was observed during the 168 days sediment was exposed to 0.1 M NaOH, at 10 C; Cs+ sorption in the presence of base was well described by the ion exchange model when enthalpy effects were considered. In contrast, at 50 C, there was a trend toward slightly lower (log {approx} 0.25) conditional equilibrium exchange constants over the entire range of surface coverage, and a slight loss of high affinity sites (15%) after 168 days of exposure to 0.1 M base solution. However, model simulations of Cs+ sorption to the sediment in the presence of 0.1 M base for 112 days were good at the lower Cs+ surface densities

  5. Effect of replacing surface inlets with blind or gravel inlets on sediment and phosphorus subsurface drainage losses.

    PubMed

    Feyereisen, Gary W; Francesconi, Wendy; Smith, Douglas R; Papiernik, Sharon K; Krueger, Erik S; Wente, Christopher D

    2015-03-01

    Open surface inlets that connect to subsurface tile drainage systems provide a direct pathway for movement of sediment, nutrients, and agrochemicals to surface waters. This study was conducted to determine the reduction in drainage effluent total suspended sediment (TSS) and phosphorus (P) concentrations and loads when open surface inlets were replaced with blind (in gravel capped with 30 cm of soil) or gravel (in very coarse sand/fine gravel) inlets. In Indiana, a pair of closed depressions in adjacent fields was fitted with open inlet tile risers and blind inlets in 2005 and monitored for flow and water chemistry. Paired comparisons on a storm event basis during the growing season for years 2006 to 2013 showed that TSS loads were 40.4 and 14.4 kg ha event for tile risers and blind inlets, respectively. Total P (TP) and soluble reactive P (SRP) loads were 66 and 50% less for the blind inlets, respectively. In Minnesota, TSS and SRP concentrations were monitored for 3 yr before and after modification of 24 open inlets to gravel inlets in an unreplicated large-field on-farm study. Median TSS concentrations were 97 and 8.3 mg L and median SRP concentrations were 0.099 and 0.064 mg L for the open inlet and gravel inlet periods, respectively. Median TSS and SRP concentrations were elevated for snowmelt vs. non-snowmelt seasons for open and gravel inlets. Both replacement designs reduced suspended sediment and P concentrations and loads. The Indiana study suggests blind inlets will be effective beyond a 10-yr service life. PMID:26023978

  6. Effect of replacing surface inlets with blind or gravel inlets on sediment and phosphorus subsurface drainage losses.

    PubMed

    Feyereisen, Gary W; Francesconi, Wendy; Smith, Douglas R; Papiernik, Sharon K; Krueger, Erik S; Wente, Christopher D

    2015-03-01

    Open surface inlets that connect to subsurface tile drainage systems provide a direct pathway for movement of sediment, nutrients, and agrochemicals to surface waters. This study was conducted to determine the reduction in drainage effluent total suspended sediment (TSS) and phosphorus (P) concentrations and loads when open surface inlets were replaced with blind (in gravel capped with 30 cm of soil) or gravel (in very coarse sand/fine gravel) inlets. In Indiana, a pair of closed depressions in adjacent fields was fitted with open inlet tile risers and blind inlets in 2005 and monitored for flow and water chemistry. Paired comparisons on a storm event basis during the growing season for years 2006 to 2013 showed that TSS loads were 40.4 and 14.4 kg ha event for tile risers and blind inlets, respectively. Total P (TP) and soluble reactive P (SRP) loads were 66 and 50% less for the blind inlets, respectively. In Minnesota, TSS and SRP concentrations were monitored for 3 yr before and after modification of 24 open inlets to gravel inlets in an unreplicated large-field on-farm study. Median TSS concentrations were 97 and 8.3 mg L and median SRP concentrations were 0.099 and 0.064 mg L for the open inlet and gravel inlet periods, respectively. Median TSS and SRP concentrations were elevated for snowmelt vs. non-snowmelt seasons for open and gravel inlets. Both replacement designs reduced suspended sediment and P concentrations and loads. The Indiana study suggests blind inlets will be effective beyond a 10-yr service life.

  7. Desorption kinetics of radiocesium from subsurface sediments at Hanford Site, USA

    NASA Astrophysics Data System (ADS)

    Liu, Chongxuan; Zachara, John M.; Smith, Steve C.; McKinley, James P.; Ainsworth, Calvin C.

    2003-08-01

    The desorption of 137Cs + was investigated on sediments from the United States Hanford site. Pristine sediments and ones that were contaminated by the accidental release of alkaline 137Cs +-containing high level nuclear wastes (HLW, 2 × 10 6 to 6 × 10 7 pCi 137Cs +/g) were studied. The desorption of 137Cs + was measured in Na +, K +, Rb +, and NH 4+electrolytes of variable concentration and pH, and in presence of a strong Cs +-specific sorbent (self-assembled monolayer on a mesoporous support, SAMMS). 137Cs + desorption from the HLW-contaminated Hanford sediments exhibited two distinct phases: an initial instantaneous release followed by a slow kinetic process. The extent of 137Cs + desorption increased with increasing electrolyte concentration and followed a trend of Rb + ≥ K + > Na + at circumneutral pH. This trend followed the respective selectivities of these cations for the sediment. The extent and rate of 137Cs + desorption was influenced by surface armoring, intraparticle diffusion, and the collapse of edge-interlayer sites in solutions containing K +, Rb +, or NH 4+. Scanning electron microscopic analysis revealed HLW-induced precipitation of secondary aluminosilicates on the edges and basal planes of micaceous minerals that were primary Cs + sorbents. The removal of these precipitates by acidified ammonium oxalate extraction significantly increased the long-term desorption rate and extent. X-ray microprobe analyses of Cs +-sorbed micas showed that the 137Cs + distributed not only on mica edges, but also within internal channels parallel to the basal plane, implying intraparticle diffusive migration of 137Cs +. Controlled desorption experiments using Cs +-spiked pristine sediment indicated that the 137Cs + diffusion rate was fast in Na +-electrolyte, but much slower in the presence of K + or Rb +, suggesting an effect of edge-interlayer collapse. An intraparticle diffusion model coupled with a two-site cation exchange model was used to interpret the

  8. Mineral-Association and Activity of Bacteria and Archaea in the Deep Subsurface South Pacific Gyre Sediment

    NASA Astrophysics Data System (ADS)

    Steele, J. A.; Dekas, A. E.; Harrison, B. K.; Morono, Y.; Inagaki, F.; Ziebis, W.; Orphan, V. J.

    2012-12-01

    Although the subsurface biosphere is now recognized as an important reservoir of life on our planet, until recently the microbial community beneath open-ocean oligotrophic gyres (making up the majority of the seafloor) has just begun to be studied in detail. IODP Expedition 329 and the KNOX-022RR site survey cruise have taken some of the first steps at characterizing the microbial community beneath the South Pacific Gyre, a region with low organic carbon burial rates (10-8 and 10-10 moles C cm-1 yr-1), deep oxygen penetration (sediments are oxidized to the basement), and low prokaryotic cell counts (106 cells cm-3 to <103 cells cm-3). In these sediments, the dominant fraction of organic carbon may be aggregated or adsorbed to minerals, suggesting that microbes that are able to grow on the minerals may create potential "hotspots" of activity. In this study, we performed magnetic separation on oligotrophic sediment samples and examined the bacterial and archaeal communities using 16S rRNA tag sequencing. To determine if the mineral-associated cells were autotrophic and/or utilizing nitrate, we performed long-term (20 month) incubations with 13CO2 and 15NO3- from sediment taken at depths ~2-70 mbsf beneath the oligotrophic gyre and outside of the oligotrophic gyre (IODP Exp. 329 stations U1368-U1371). Subsequently we used the DNA stain SYBR Green I, and CARD-FISH-NanoSIMS to identify cells which were actively taking up the isotopic label. We then used SEM-EDS to identify the mineral particle composition. Preliminary results found the magnetic fraction in oligotrophic sediment (KNOX-022RR station SPG-5) from 1.2-2.6 mbsf showed a greater diversity of both bacteria and archaea. OTUs from Chloroflexi groups SO85 and SAR202 were dominant in the magnetic fraction. Firmicutes, Bacteroidetes, δ-Proteobacteria, Verrucomicrobia, Deferribacteres, WS3, OP10, and OP1 OTUs were found only in the magnetic fraction. Crenarchaeal OTUs from Marine Benthic Group B and Marine Group I

  9. Protozoa in Subsurface Sediments from Sites Contaminated with Aviation Gasoline or Jet Fuel

    PubMed Central

    Sinclair, James L.; Kampbell, Don H.; Cook, Mike L.; Wilson, John T.

    1993-01-01

    Numbers of protozoa in the subsurface of aviation gasoline and jet fuel spill areas at a Coast Guard base at Traverse City, Mich., were determined. Boreholes were drilled in an uncontaminated location, in contaminated but untreated parts of the fuel plumes, and in the aviation gasoline source area undergoing H2O2 biotreatment. Samples were taken from the unsaturated zone to depths slightly below the floating free product in the saturated zone. Protozoa were found to occur in elevated numbers in the unsaturated zone, where fuel vapors mixed with atmospheric oxygen, and below the layer of floating fuel, where uncontaminated groundwater came into contact with fuel. The same trends were noted in the biotreatment area, except that numbers of protozoa were higher. Numbers of protozoa in some contaminated areas equalled or exceeded those found in surface soil. The abundance of protozoa in the biotreatment area was high enough that it would be expected to significantly reduce the bacterial community that was degrading the fuel. Little reduction in hydraulic conductivity was observed, and no bacterial fouling of the aquifer was observed during biotreatment. PMID:16348871

  10. MICROSCALE METABOLIC, REDOX AND ABIOTIC REACTIONS IN HANFORD 300 AREA SUBSURFACE SEDIMENTS

    SciTech Connect

    Beyenal, Haluk; McLEan, Jeff; Majors, Paul; Fredrickson, Jim

    2013-11-14

    The Hanford 300 Area is a unique site due to periodic hydrologic influence of river water resulting in changes in groundwater elevation and flow direction. This area is also highly subject to uranium remobilization, the source of which is currently believed to be the region at the base of the vadose zone that is subject to period saturation due to the changes in the water levels in the Columbia River. We found that microbial processes and redox and abiotic reactions which operate at the microscale were critical to understanding factors controlling the macroscopic fate and transport of contaminants in the subsurface. The combined laboratory and field research showed how microscale conditions control uranium mobility and how biotic, abiotic and redox reactions relate to each other. Our findings extended the current knowledge to examine U(VI) reduction and immobilization using natural 300 Area communities as well as selected model organisms on redox-sensitive and redox-insensitive minerals. Using innovative techniques developed specifically to probe biogeochemical processes at the microscale, our research expanded our current understanding of the roles played by mineral surfaces, bacterial competition, and local biotic, abiotic and redox reaction rates on the reduction and immobilization of uranium.

  11. Protozoa in subsurface sediments from sites contaminated with aviation gasoline or jet fuel.

    PubMed

    Sinclair, J L; Kampbell, D H; Cook, M L; Wilson, J T

    1993-02-01

    Numbers of protozoa in the subsurface of aviation gasoline and jet fuel spill areas at a Coast Guard base at Traverse City, Mich., were determined. Boreholes were drilled in an uncontaminated location, in contaminated but untreated parts of the fuel plumes, and in the aviation gasoline source area undergoing H(2)O(2) biotreatment. Samples were taken from the unsaturated zone to depths slightly below the floating free product in the saturated zone. Protozoa were found to occur in elevated numbers in the unsaturated zone, where fuel vapors mixed with atmospheric oxygen, and below the layer of floating fuel, where uncontaminated groundwater came into contact with fuel. The same trends were noted in the biotreatment area, except that numbers of protozoa were higher. Numbers of protozoa in some contaminated areas equalled or exceeded those found in surface soil. The abundance of protozoa in the biotreatment area was high enough that it would be expected to significantly reduce the bacterial community that was degrading the fuel. Little reduction in hydraulic conductivity was observed, and no bacterial fouling of the aquifer was observed during biotreatment.

  12. An Integrated Assessment of Geochemical and Community Structure Determinants of Metal Reduction Rates in Subsurface Sediments

    SciTech Connect

    Joel E. Kostka

    2008-03-24

    This project represented a joint effort between Oak Ridge National Laboratory (ORNL), the University of Tennessee (UT), and Florida State University (FSU). ORNL served as the lead in-stitution with Dr. A.V. Palumbo responsible for project coordination, integration, and deliver-ables. In situ uranium bioremediation is focused on biostimulating indigenous microorganisms through a combination of pH neutralization and the addition of large amounts of electron donor. Successful biostimulation of U(VI) reduction has been demonstrated in the field and in the laboratory. However, little data is available on the dynamics of microbial populations capable of U(VI) reduction, and the differences in the microbial community dynamics between proposed electron donors have not been explored. In order to elucidate the potential mechanisms of U(VI) reduction for optimization of bioremediation strategies, structure-function relationships of microbial populations were investigated in microcosms of subsurface materials cocontaminated with radionuclides and nitrate from the Oak Ridge Field Research Center (ORFRC), Oak Ridge, Tennessee.

  13. Lab-scale simulation of the fate and transport of nano zero-valent iron in subsurface environments: aggregation, sedimentation, and contaminant desorption.

    PubMed

    Yin, Ke; Lo, Irene M C; Dong, Haoran; Rao, Pinhua; Mak, Mark S H

    2012-08-15

    Heavy metal removal using nano zero-valent iron (NZVI) has drawn growing attention due to the ease of application and high removal efficiency. However, uncertainties regarding its fate and transport in subsurface environments have raised concerns that require further exploration. In this study, aggregation, sedimentation, and Cr/As desorption of three types of NZVIs were investigated under various conditions. It was found that the aggregation behavior of the NZVIs differed from one another in regard to reaction time and ionic strength, associated with the respective critical size for sedimentation. Sedimentation of NZVIs was positively related to the concentrations and average particle sizes. The sedimentation kinetics of NZVI followed two concomitant processes, i.e., (1) direct sedimentation of larger particles, and (2) initial aggregation and then sedimentation of smaller particles. When loaded with Cr/As, NZVIs tended to deposit faster, possibly due to the precipitation of Cr/As onto the nanoparticle surfaces resulting in larger particle sizes. Moreover, desorption of Cr/As from Cr/As loaded NZVIs was detected in the presence of typical groundwater ions, as well as natural organic matter, and poses a potential risk to the subsurface environment. The desorption of Cr was linearly related to the release of iron ions, while As desorption was mitigated when the immobilization of Cr increased.

  14. A New Sensitive GC-MS-based Method for Analysis of Dipicolinic Acid and Quantifying Bacterial Endospores in Deep Marine Subsurface Sediment

    NASA Astrophysics Data System (ADS)

    Fang, J.

    2015-12-01

    Marine sediments cover more than two-thirds of the Earth's surface and represent a major part of the deep biosphere. Microbial cells and microbial activity appear to be widespread in these sediments. Recently, we reported the isolation of gram-positive anaerobic spore-forming piezophilic bacteria and detection of bacterial endospores in marine subsurface sediment from the Shimokita coalbed, Japan. However, the modern molecular microbiological methods (e.g., DNA-based microbial detection techniques) cannot detect bacterial endospore, because endospores are impermeable and are not stained by fluorescence DNA dyes or by ribosomal RNA staining techniques such as catalysed reporter deposition fluorescence in situ hybridization. Thus, the total microbial cell abundance in the deep biosphere may has been globally underestimated. This emphasizes the need for a new cultivation independent approach for the quantification of bacterial endospores in the deep subsurface. Dipicolinic acid (DPA, pyridine-2,6-dicarboxylic acid) is a universal and specific component of bacterial endospores, representing 5-15wt% of the dry spore, and therefore is a useful indicator and quantifier of bacterial endospores and permits to estimate total spore numbers in the subsurface biosphere. We developed a sensitive analytical method to quantify DPA content in environmental samples using gas chromatography-mass spectrometry. The method is sensitive and more convenient in use than other traditional methods. We applied this method to analyzing sediment samples from the South China Sea (obtained from IODP Exp. 349) to determine the abundance of spore-forming bacteria in the deep marine subsurface sediment. Our results suggest that gram-positive, endospore-forming bacteria may be the "unseen majority" in the deep biosphere.

  15. Distribution of microbial biomass and the potential for anaerobic respiration in Hanford Site 300 Area subsurface sediment

    SciTech Connect

    Lin, Xueju; Kennedy, David W.; Peacock, Aaron D.; McKinley, James P.; Resch, Charles T.; Fredrickson, Jim K.; Konopka, Allan

    2012-02-01

    Subsurface sediments were recovered from a 52 m deep borehole cored in the 300 Area of the Hanford Site in southeastern Washington State to assess the potential for biogeochemical transformation of radionuclide contaminants. Microbial analyses were made on 17 sediment samples traversing multiple geological units: the oxic coarse-grained Hanford formation (9-17.4 m), the oxic fine-grained upper Ringold Formation (17.7-18.1 m), and the reduced Ringold Formation (18.3-52m). Microbial biomass (measured as phospholipid) ranged from 7-974 pmols per g in discrete samples, with the highest numbers found in the Hanford formation. On average, strata below 17.4 m had 13-fold less biomass than those from shallower strata. The nosZ gene encoding nitrous oxide reductase had an abundance of 5-17% relative to total 16S rRNA genes below 18.3 m and <5% above 18.1 m. Most nosZ sequences were affiliated with Ochrobactrum anthropi (97% sequence similarity) or had a nearest neighbor of Achromobacter xylosoxidans (90% similarity). Passive multilevel sampling of groundwater geochemistry demonstrated a redox gradient in the 1.5 m region between the Hanford-Ringold formation contact and the Ringold oxic-anoxic interface. Within this zone, copies of the dsrA gene and Geobacteraceae had the highest relative abundance. The majority of dsrA genes detected near the interface were related to Desulfotomaculum sp.. These analyses indicate that the region just below the contact between the Hanford and Ringold formations is a zone of active biogeochemical redox cycling.

  16. Intrinsic Anaerobic Bioremediation of Hydrocarbons in Contaminated Subsurface Plumes and Marine Sediments

    NASA Astrophysics Data System (ADS)

    Nanny, M. A.; Nanny, M. A.; Suflita, J. M.; Suflita, J. M.; Davidova, I.; Kropp, K.; Caldwell, M.; Philp, R.; Gieg, L.; Rios-Hernandez, L. A.

    2001-05-01

    In recent years, several classes of petroleum hydrocarbons contaminating subsurface and marine environments have been found susceptible to anaerobic biodegradation using novel mechanisms entirely distinct from aerobic metabolic pathways. For example, the anaerobic decay of toluene can be initiated by the addition of the aryl methyl group to the double bond of fumarate, resulting in a benzylsuccinic acid metabolite. Our work has shown that an analogous mechanism also occurs with ethylbenzene and the xylene isomers, yielding 3-phenyl-1,2-butane dicarboxylic acid and methylbenzylsuccinic acid, respectively. Moreover, these metabolites have been detected in contaminated environments. Most recently, we have identified metabolites resulting from the initial attack of H26- or D26-n-dodecane during degradation by a sulfate-reducing bacterial culture. Using GC-MS, these metabolites were identified as fatty acids that result from C-H or C-D addition across the double bond of fumarate to give dodecylsuccinic acids in which all 26 protons or deuteriums of the parent alkane were retained. Further, when this enrichment culture was challenged with hexane or decane, hexylsuccinic acid or decylsuccinic acid were identified as resulting metabolites. Similarly, the study of an ethylcyclopentane-degrading sulfate-reducing enrichment produced a metabolite, which is consistent with the addition of fumarate to the parent substrate. These novel anaerobic addition products are characterized by similar, distinctive mass spectral (MS) features (ions specific to the succinic acid portion of the molecule) that can potentially be used to probe contaminated environments for evidence of intrinsic remediation of hydrocarbons. Indeed, analyses of water extracts from two gas condensate-contaminated sites resulted in the tentative detection of alkyl- and cycloalkylsuccinic acids ranging from C3 to C9, including ethylcyclopentyl-succinic acid. In water extracts collected from an area underlying a

  17. Assessing production of the ubiquitous archaeal diglycosyl tetraether lipids in marine subsurface sediment using intramolecular stable isotope probing.

    PubMed

    Lin, Yu-Shih; Lipp, Julius S; Elvert, Marcus; Holler, Thomas; Hinrichs, Kai-Uwe

    2013-05-01

    The membrane lipids diglycosyl-glycerol dibiphytanyl glycerol tetraethers (2G-GDGTs) in marine subsurface sediments are believed to originate from uncultivated benthic archaea, yet the production of 2G-GDGTs from subseafloor samples has not been demonstrated in vitro. In order to validate sedimentary biosynthesis of 2G-GDGTs, we performed a stable carbon isotope probing experiment on a subseafloor sample with six different (13) C-labelled substrates (bicarbonate, methane, acetate, leucine, glucose and Spirulina platensis biomass). After 468 days of anoxic incubation, only glucose and S. platensis resulted in label uptake in lipid moieties of 2G-GDGTs, indicating incorporation of carbon from these organic substrates. The hydrophobic moieties of 2G-GDGTs showed minimal label incorporation, with up to 4‰ (13) C enrichment detected in crenarchaeol-derived tricyclic biphytane from the S. platensis-supplemented slurries. The 2G-GDGT-derived glucose or glycerol moieties also showed (13) C incorporation (Δδ(13) C = 18-38‰) in the incubations with glucose or S. platensis, consistent with a lipid salvage mechanism utilized by marine benthic archaea to produce new 2G-GDGTs. The production rates were nevertheless rather slow, even when labile organic matter was supplied. The 2G-GDGT turnover times of 1700-20,500 years were much longer than those estimated for subseafloor microbial communities, implying that sedimentary 2G-GDGTs as biomarkers of benthic archaea are cumulative records of past and present generations.

  18. Dissimilatory Bacterial Reduction of Al-Substituted Goethite in Subsurface Sediments

    SciTech Connect

    Kukkadapu, Ravi K.; Zachara, John M.; Smith, Steven C.; Fredrickson, Jim K.; Liu, Chongxuan

    2001-09-13

    Microbiologic reduction of the 0.2-2.0 mm size fraction of an Atlantic coastal plain sediment (Eatontown) was investigated using a dissimilatory Fe(III)-reducing bacterium (Shewanella putrefaciens, strain CN32) to evaluate mineralogic controls on the rate and extent of Fe(III) reduction and resulting distribution of biogenic Fe(II). Mössbauer spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) was used to show that the sedimentary Fe(III) oxide was Al-substituted goethite (11-17% Al) that existed as 1-5 mm aggregates of indistinct morphology. Bioreduction experiments were performed in two buffers [HCO3-, 1,4-piperazinediethansulfonic acid (PIPES)] both without and with 2,6-anthraquinone disulfonate (AQDS), an electron shuttle. The production of biogenic Fe(II) and the distribution of Al (aqueous and sorbed) were followed over time, as was formation of Fe(II) biominerals and physical/chemical changes to the goethite.

  19. Fixation Mechanisms and Desorption Rates of Sorbed Cs in High-Level Waste Contaminated Subsurface Sediments: Implications to Future Behavior and In-Ground Stability

    SciTech Connect

    Zachara, John M.; McKinley, James P.; Ainsworth, Calvin C.; Serne, R. Jeff

    2002-06-01

    Research is investigating mineralogic and geochemical factors controlling the desorption rate of 137Cs+ from subsurface sediments on the Hanford Site contaminated with different types of high level waste. The project will develop kinetic data and models that describe the release rates of 137Cs+ from contaminated sediments over a range of potential geochemical conditions that may evolve during waste retrieval from overlying tanks, or in response to meteoric water infiltration. Scientific understanding and computational techniques will be established to predict the future behavior of sorbed, in-ground 137Cs+.

  20. Fixation Mechanisms and Desorption Rates of Sorbed Cs in High-Level Waste Contaminated Subsurface Sediments: Implications to Future Behavior and In-Ground Stability

    SciTech Connect

    Zachara, John M.; McKinley, James P.; Ainsworth, Calvin C.; Serne, R. Jeff

    2001-06-01

    The high-yield fission product 137Cs is a major contaminant of the vadose zone at Hanford and other DOE sites. Over 100 kCi of 137Cs was discharged to the vadose zone in the S-SX tank farm at Hanford through the leakage of high-level waste from tanks SX-108 and SX-109. Although 137Cs is strongly sorbed by subsurface sediments, certain waste characteristics, such as high Na+, can expedite its migration and reduce its retardation to low values. This project is focused on defining the in-ground geochemistry of sorbed 137Cs released from high-level waste tanks, so that better future projections can be made of Cs mobility in the vadose zone. The project will study Cs-contaminated subsurface sediments from various Hanford tank farms to (1) determine the mineralogic and surface site residence of sorbed Cs in contaminated sediments varying in current Cs content and original waste composition, (2) establish geochemical factors and processes controlling Cs desorbability and desorption kinetics from contaminated sediment and Cs-enriched sediment particles, and (3) define and parameterize a kinetic model for Cs desorption that incorporates multi-site behavior and heterogeneous intraparticle Cs distribution.

  1. Dissimilatory bacterial reduction of Al-substituted goethite in subsurface sediments

    NASA Astrophysics Data System (ADS)

    Kukkadapu, Ravi K.; Zachara, John M.; Smith, Steven C.; Fredrickson, James K.; Liu, Chongxuan

    2001-09-01

    The microbiologic reduction of a 0.2 to 2.0 μm size fraction of an Atlantic coastal plain sediment (Eatontown) was investigated using a dissimilatory Fe(III)-reducing bacterium ( Shewanella putrefaciens, strain CN32) to evaluate mineralogic controls on the rate and extent of Fe(III) reduction and the resulting distribution of biogenic Fe(II). Mössbauer spectroscopy and X-ray diffraction (XRD) were used to show that the sedimentary Fe(III) oxide was Al-substituted goethite (13-17% Al) that existed as 1- to 5-μm aggregates of indistinct morphology. Bioreduction experiments were performed in two buffers [HCO 3-; 1,4-piperazinediethansulfonic acid (PIPES)] both without and with 2,6-anthraquinone disulfonate (AQDS) as an electron shuttle. The production of biogenic Fe(II) and the distribution of Al (aqueous and sorbed) were followed over time, as was the formation of Fe(II) biominerals and physical/chemical changes to the goethite. The extent of reduction was comparable in both buffers. The reducibility (rate and extent) was enhanced by AQDS; 9% of dithionite-citrate-bicarbonate (DCB) extractable Fe(III) was reduced without AQDS whereas 15% was reduced in the presence of AQDS. XRD and Mössbauer spectroscopy were used to monitor the disposition of biogenic Fe(II) and changes to the Al-goethite. Fe(II) biomineralization was not evident by XRD. Biomineralization was observed by Mössbauer when sorbed Fe(II) concentrations exceeded a threshold value. The biomineralization products displayed Mössbauer spectra consistent with siderite FeCO 3 (HCO 3- buffer only) and green rust [Fe (6-x)IIFe xIII(OH) 12] x+[(A 2-) x/2. yH 2O] x-. Adsorption of biogenic Fe(II) to accessory mineral phases (e.g., kaolinite) and bacterial surfaces appeared to limit biomineralization. Al evolved during reduction was sorbed, and extractable Al increased with reduction. XRD analysis indicated that neither crystallite size or the Al content of the goethite was affected by bacterial reduction, i

  2. The effects of temperature and motility on the advective transport of a deep subsurface bacteria through saturated sediment

    SciTech Connect

    McCaulou, D.R.

    1993-10-01

    Replicate column experiments were done to quantify the effects of temperature and bacterial motility on advective transport through repacked, but otherwise unaltered, natural aquifer sediment. The bacteria used in this study, A0500, was a flagellated, spore-forming rod isolated from the deep subsurface at DOE`s Savannah River Laboratory. Motility was controlled by turning on flagellar metabolism at 18{degrees}C but off at 40{degrees}C. Microspheres were used to independently quantify the effects of temperature on the sticking efficiency ({alpha}), estimated using a steady-state filtration model. The observed greater microsphere removal at the higher temperature agreed with the physical-chemical model, but bacteria removal at 18{degrees}C was only half that at 4{degrees}C. The sticking efficiency for non-motile A0500 (4{degrees}C) was over three times that of the motile A0500 (18{degrees}C), 0.073 versus 0.022 respectively. Analysis of complete breakthrough curves using a non-steady, kinetically limited, transport model to estimate the time scales of attachment and detachment suggested that motile A 0500 bacteria traveled twice as far as non-motile A 0500 bacteria before becoming attached. Once attached, non-motile colloids detached on the time scale of 9 to 17 days. The time scale for detachment of motile A0500 bacteria was shorter, 4 to 5 days. Results indicate that bacterial attachment was reversible and detachment was enhanced by bacterial motifity. The kinetic energy of bacterial motility changed the attachment-detachment kinetics in favor of the detached state. The chemical factors responsible for the enhanced transport are not known. However, motility may have caused weakly held bacteria to detach from the secondary minimum, and possibly from the primary minimum, as described by DLVO theory.

  3. Immobilization of U(VI) from Oxic Groundwater by Hanford 300 Area Sediments and Effects of Columbia River Water

    SciTech Connect

    Ahmed, B.; Cao, Bin; Mishra, Bhoopesh; Boyanov, Maxim I.; Kemner, Kenneth M.; Fredrickson, Jim K.; Beyenal, Haluk

    2012-09-23

    Regions within the U.S. Department of Energy Hanford 300 Area (300 A) site experience periodic hydrologic influences from the nearby Columbia River as a result of changing river stage, which causes changes in groundwater elevation, flow direction and water chemistry. An important question is the extent to which the mixing of Columbia River water and groundwater impacts the speciation and mobility of uranium (U). In this study, we designed experiments to mimic interactions among U, oxic groundwater or Columbia River water, and 300 A sediments in the subsurface environment of Hanford 300 A. The goals were to investigate mechanisms of: 1) U immobilization in 300 A sediments under bulk oxic conditions and 2) U remobilization from U-immobilized 300 A sediments exposed to oxic Columbia River water. Initially, 300 A sediments in column reactors were fed with U(VI)-containing oxic 1) synthetic groundwater (SGW), 2) organic-amended SGW (OA-SGW), and 3) de-ionized (DI) water to investigate U immobilization processes. After that, the sediments were exposed to oxic Columbia River water for U remobilization studies. The results reveal that U was immobilized by 300 A sediments predominantly through reduction (80-85%) when the column reactor was fed with oxic OA-SGW. However, U was immobilized by 300 A sediments through adsorption (100%) when the column reactors were fed with oxic SGW or DI water. The reduced U in the 300 A sediments fed with OA-SGW was relatively resistant to remobilization by oxic Columbia River water. Oxic Columbia River water resulted in U remobilization (~7%) through desorption, and most of the U that remained in the 300 A sediments fed with OA-SGW (~93%) was in the form of uraninite nanoparticles. These results reveal that: 1) the reductive immobilization of U through OA-SGW stimulation of indigenous 300 A sediment microorganisms may be viable in the relatively oxic Hanford 300 A subsurface environments and 2) with the intrusion of Columbia River water

  4. The new CutSprof sampling tool and method for micromorphological and microfacies analyses of subsurface salt marsh sediments, Algarve, Portugal

    NASA Astrophysics Data System (ADS)

    Araújo-Gomes, João; Ramos-Pereira, Ana

    2015-02-01

    A new tool and method for collecting undisturbed subsurface samples in estuarine environments by means of trenching, timbering and sectioning is presented. Smoothing of sidewalls is achieved by a so-called cutting sediment profiler (CutSprof), while water draining into the trench is cleared by pumping. From smoothed sidewall sections, undisturbed thin sediment slices can then be collected for micromorphological and microfacies analyses. Results demonstrating the successful application of this procedure are presented for salt marshes of the Bensafrim River estuary (Lagos, Algarve, Portugal). In addition to palaeo-reconstructions in salt marsh settings, the CutSprof would be highly suitable in various other research domains as well as for environmental management purposes, particularly where sampling below the groundwater table is desirable to explore, for example, animal-sediment relationships in tidal-flat and mangrove ecosystems as well as the dynamics of coastal wetlands today threatened by ever-increasing anthropogenic influence.

  5. Biogeochemical dynamics of amino acids in deep-subsurface marine sediments: Constraints from compound-specific nitrogen isotopic composition and enantiomer ratio

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Y. T.; Chikaraishi, Y.; Takano, Y.; Ogawa, N. O.; Suga, H.; Yokoyama, Y.; Ohkouchi, N.

    2013-12-01

    Vast microbial populations exist in deep-subsurface marine sediments. Although amino acids in sediment pore waters are key compounds in metabolic activities of sedimentary microbes and in remineralization of carbon and nitrogen, to date little is known about their biogeochemical dynamics (e.g., sources and transformation processes) in deep-subsurface sediments. As a new approach to constrain the sources of dissolved amino acids in sediment pore waters, we analyzed compound-specific nitrogen isotopic composition (d15N) and enantiomer ratio (%D) of total hydrolysable amino acids (THAA) in sediment solid phase and dissolved hydrolysable amino acids (DHAA) in sediment pore waters from the same sediment samples. Enantiomer ratio can be an indicator of source organisms of amino acids, because specific D-amino acids (such as alanine, aspartic acid, glutamic acid, and serine) are commonly found in the cell wall complex of bacteria. Compound-specific d15N can be an indicator of microbial metabolism of amino acids, because biosynthesis and degradation of amino acids cause nitrogen isotopic fractionation. Samples were collected from deep-subsurface sediments (up to 172.9 m below seafloor) at the Sagami Trough (Northwestern Pacific) during D/V Chikyu cruise CK09-03. In the sediments deeper than 9 mbsf, %D values of DHAA were 25.9×2.8% in alanine, 24.8×2.1% in aspartic acid, 11.3×2.8% in serine, and 16.3×2.7% in glutamic acid, and %D changes from THAA were +15.3×2.1% in alanine, -0.4×2.4% in aspartic acid, -8.1×6.2% in serine, and 4.6×3.3% in glutamic acid. Compound-specific d15N analysis showed that d15N values of alanine are higher in DHAA than THAA and that d15N values of glycine and glutamic acid are similar between the two fractions (d15N of DHAA - d15N of THAA = +5.8×2.3 permill, +1.9×0.6 permill, -0.3×1.1 permill, respectively). The differences of d15N and %D signatures between DHAA and THAA suggest that the depolymerization of THAA is not the sole source of

  6. Vernal Crater, SW Arabia Terra: MSL Candidate with Extensively Layered Sediments, Possible Lake Deposits, and a Long History of Subsurface Ice

    NASA Technical Reports Server (NTRS)

    Oehler, Dorothy Z.; Allen, Carlton C.

    2007-01-01

    Vernal Crater is a Mars Science Laboratory (MSL) landing site candidate providing relatively easy access to extensively layered sediments as well as potential lake deposits. Sediments of Vernal Crater are 400-1200 m below those being investigated by Opportunity in Meridiani Planum, and as such would allow study of significantly older geologic units, if Vernal Crater were selected for MSL. The location of Vernal Crater in SW Arabia Terra provides exceptional scientific interest, as rampart craters and gamma-ray spectrometer (GRS) data from the region suggest a long history of ice/fluids in the subsurface. The potential value of this MSL candidate is further enhanced by reports of atmospheric methane over Arabia, as any insight into the source of that methane would significantly increase our understanding of Mars. Finally, should MSL survive beyond its prime mission, the gentle slope within Vernal Crater would provide a route out of the crater for study of the once ice/fluid-rich plains.

  7. [The first results of a study of the phylogenetic diversity of microorganisms in southern Baikal sediments from the area of subsurface depositions of methane hydrates].

    PubMed

    Shubenkova, O V; Zemskaia, T I; Chernitsyna, S M; Khlystov, O M; Triboĭ, T I

    2005-01-01

    Phylogenetic analysis of the bacterial communities in Lake Baikal bottom sediments in the region of subsurface methane hydrate depositions has been carried out using data on 16S rRNA sequences. The composition of these microbial communities is shown to be different in different horizons. Methanotrophic bacteria are found in the surface layer (0-5 cm), and uncultured bacteria constitute a great portion of this population. In deeper sediment layers (92-96 cm), achange in the microbial community occurs; specifically, a decreased homology with the known sequences is observed. The new sequences form separate clusters on a phylogenetic tree, indicating the possibly endemic nature of the bacteria revealed. Organisms related to the genus Pseudomonas constitute the main portion of the population. An archaea-related sequence was found in a horizon containing gas hydrate crystals (100-128 cm). Uncultured bacteria remain predominant. PMID:16119851

  8. Porosity and Organic Carbon Controls on Naturally Reduced Zone (NRZ) Formation Creating Microbial ';Hotspots' for Fe, S, and U Cycling in Subsurface Sediments

    NASA Astrophysics Data System (ADS)

    Jones, M. E.; Janot, N.; Bargar, J.; Fendorf, S. E.

    2013-12-01

    Previous studies have illustrated the importance of Naturally Reduced Zones (NRZs) within saturated sediments for the cycling of metals and redox sensitive contaminants. NRZs can provide a source of reducing equivalents such as reduced organic compounds or hydrogen to stimulate subsurface microbial communities. These NRZ's are typically characterized by low permeability and elevated concentrations of organic carbon and trace metals. However, both the formation of NRZs and their importance to the overall aquifer carbon remineralization is not fully understood. Within NRZs the hydrolysis of particulate organic carbon (POC) and subsequent fermentation of dissolved organic carbon (DOC) to form low molecular weight dissolved organic carbon (LMW-DOC) provides electron donors necessary for the respiration of Fe, S, and in the case of the Rifle aquifer, U. Rates of POC hydrolysis and subsequent fermentation have been poorly constrained and rates in excess and deficit to the rates of subsurface anaerobic respiratory processes have been suggested. In this study, we simulate the development of NRZ sediments in diffusion-limited aggregates to investigate the physical and chemical conditions required for NRZ formation. Effects of sediment porosity and POC loading on Fe, S, and U cycling on molecular and nanoscale are investigated with synchrotron-based Near Edge X-ray Absorption Fine Structure Spectroscopy (NEXAFS). Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) and Fourier Transform Infrared spectroscopy (FTIR) are used to characterize the transformations in POC and DOC. Sediment aggregates are inoculated with the natural microbial biota from the Rifle aquifer and population dynamics are monitored by 16S RNA analysis. Overall, establishment of low permeability NRZs within the aquifer stimulate microbial respiration beyond the diffusion-limited zones and can limit the transport of U through a contaminated aquifer. However, the long-term stability of

  9. In situ redox manipulation of subsurface sediments from Fort Lewis, Washington: Iron reduction and TCE dechlorination mechanisms

    SciTech Connect

    JE Szecsody; JS Fruchter; DS Sklarew; JC Evans

    2000-03-21

    Pacific Northwest National Laboratory (PNNL) conducted a bench-scale study to determine how effective chemically treated Ft. Lewis sediments can degrade trichloroethylene (TCE). The objectives of this experimental study were to quantify: (1) sediment reduction and oxidation reactions, (2) TCE degradation reactions, and (3) other significant geochemical changes that occurred. Sediment reduction and oxidation were investigated to determine the mass of reducible iron in the Ft. Lewis sediments and the rate of this reduction and subsequent oxidation at different temperatures. The temperature dependence was needed to be able to predict field-scale reduction in the relatively cold ({approximately}11 C) Ft. Lewis aquifer. Results of these experiments were used in conjunction with other geochemical and hydraulic characterization to design the field-scale injection experiment and predict barrier longevity. For example, the sediment reduction rate controls the amount of time required for the dithionite solution to fully react with sediments. Sediment oxidation experiments were additionally conducted to determine the oxidation rate and provide a separate measure of the mass of reduced iron. Laboratory experiments that were used to meet these objectives included: (1) sediment reduction in batch (static) systems, (2) sediment reduction in 1-D columns, and (3) sediment oxidation in 1-D columns. Multiple reaction modeling was conducted to quantify the reactant masses and reaction rates.

  10. Diversity, abundance, and distribution of NO-forming nitrite reductase-encoding genes in deep-sea subsurface sediments of the South China Sea.

    PubMed

    Li, M; Hong, Y; Cao, H; Klotz, M G; Gu, J-D

    2013-03-01

    In marine ecosystems, both nitrite-reducing bacteria and anaerobic ammonium-oxidizing (anammox) bacteria, containing different types of NO-forming nitrite reductase-encoding genes, contribute to the nitrogen cycle. The objectives of study were to reveal the diversity, abundance, and distribution of NO-forming nitrite reductase-encoding genes in deep-sea subsurface environments. Results showed that higher diversity and abundance of nirS gene than nirK and Scalindua-nirS genes were evident in the sediments of the South China Sea (SCS), indicating bacteria containing nirS gene dominated the NO-forming nitrite-reducing microbial community in this ecosystem. Similar diversity and abundance distribution patterns of both nirS and Scalindua-nirS genes were detected in this study sites, but different from nirK gene. Further statistical analyses also showed both nirS and Scalindua-nirS genes respond similarly to environmental factors, but differed from nirK gene. These results suggest that bacteria containing nirS and Scalindua-nirS genes share similar niche in deep-sea subsurface sediments of the SCS, but differed from those containing nirK gene, indicating that community structures of nitrite-reducing bacteria are segregated by the functional modules (NirS vs. NirK) rather than the competing processes (anammox vs. classical denitrification). PMID:23398962

  11. Diversity, abundance, and distribution of NO-forming nitrite reductase-encoding genes in deep-sea subsurface sediments of the South China Sea.

    PubMed

    Li, M; Hong, Y; Cao, H; Klotz, M G; Gu, J-D

    2013-03-01

    In marine ecosystems, both nitrite-reducing bacteria and anaerobic ammonium-oxidizing (anammox) bacteria, containing different types of NO-forming nitrite reductase-encoding genes, contribute to the nitrogen cycle. The objectives of study were to reveal the diversity, abundance, and distribution of NO-forming nitrite reductase-encoding genes in deep-sea subsurface environments. Results showed that higher diversity and abundance of nirS gene than nirK and Scalindua-nirS genes were evident in the sediments of the South China Sea (SCS), indicating bacteria containing nirS gene dominated the NO-forming nitrite-reducing microbial community in this ecosystem. Similar diversity and abundance distribution patterns of both nirS and Scalindua-nirS genes were detected in this study sites, but different from nirK gene. Further statistical analyses also showed both nirS and Scalindua-nirS genes respond similarly to environmental factors, but differed from nirK gene. These results suggest that bacteria containing nirS and Scalindua-nirS genes share similar niche in deep-sea subsurface sediments of the SCS, but differed from those containing nirK gene, indicating that community structures of nitrite-reducing bacteria are segregated by the functional modules (NirS vs. NirK) rather than the competing processes (anammox vs. classical denitrification).

  12. Interstitial fluid chemistry of sediments underlying the North Atlantic gyre and the influence of subsurface fluid flow

    NASA Astrophysics Data System (ADS)

    Ziebis, Wiebke; McManus, James; Ferdelman, Timothy; Schmidt-Schierhorn, Friederike; Bach, Wolfgang; Muratli, Jesse; Edwards, Katrina J.; Villinger, Heinrich

    2012-03-01

    The western flank of the Mid-Atlantic Ridge is a region underlying the oligotrophic waters of the central Atlantic. The seafloor along portions of this ridge is characterized by sediment-filled depressions, which are surrounded by steep basaltic outcrops. We present pore fluid and sediment solid-phase chemical data from fourteen gravity cores from "North Pond", a sediment pond where previous drilling work indicated directed flow of seawater within the basement. Sediment lithology is broadly characterized as a nannofossil pelagic sediment containing varying amounts of clay, foraminifers, and Mn-micronodules and typically contains less than 0.3% organic carbon and ~ 70% calcium carbonate. Consistent with its location within an oligotrophic ocean gyre, oxygen and nitrate penetrated deeply into the sediment package. However there is significant spatial variability in the pore fluid nitrate and oxygen profiles, with oxygen generally lower and nitrate higher toward the center of the basin as compared to the edges. In addition, oxygen increased with sediment depth at a number of sites toward the edges of the pond, where sediment cover was thinnest. We interpret these oxygen distributions to indicate that there is upward diffusion of dissolved oxygen from the underlying basaltic basement fluid and the sediment package, and this process appears to be regionally pervasive. Pore fluid molybdenum generally decreases with depth and exhibits spatial variability similar to dissolved oxygen and nitrate. Molybdenum is likely being taken up at depth via adsorption onto manganese oxides, as these sediments are rich in manganese (~ 300-3000 ppm Mn) and molybdenum (~ 2-14 ppm Mo). The strong geographical variations in pore fluid chemistry coupled with the co-variation between molybdenum and oxygen, two species that we would not necessarily expect to be coupled, suggest that diffusion of dissolved constituents into the sediment package from below plays an important role in determining

  13. In Situ Redox Manipulation of Subsurface Sediments from Fort Lewis, Washington: Iron Reduction and TCE Dechlorination Mechanisms

    SciTech Connect

    Szecsody, James E.; Fruchter, Jonathan S.; Sklarew, Deborah S.; Evans, John C.

    2000-03-17

    The feasibility of chemically treating sediments from the Ft. Lewis, Washington, Logistics Center to develop a permeable barrier for dechlorination of TCE was investigated in a series of laboratory experiments.

  14. The effect of biogenic Fe(II) on the stability and sorption of Co(II)EDTA{sup 2{minus}} to goethite and a subsurface sediment

    SciTech Connect

    Zachara, J.M.; Smith, S.C.; Fredrickson, J.K.

    2000-04-01

    Laboratory experiments were conducted with suspensions of goethite ({alpha}-FeOOH) and a subsurface sediment to assess the influence of bacterial iron reduction on the fate of Co(II)EDTA{sup 2{minus}}, a representative metal-ligand complex of intermediate stability (log K{sub Co(II)EDTA} = 17.97). The goethite was synthetic (ca. 55 m{sup 2}/g) and the sediment was a Pleistocene age, Fe(III) oxide-containing material from the Atlantic coastal plain (Milford). Shewanella alga strain BrY, a dissimulatory iron reducing bacterium (DIRB), was used to promote Fe(III) oxide reduction. Sorption isotherms and pH adsorption edges were measured for Co{sup 2+}, Fe{sup 2+}, Co(II)EDTA{sup 2{minus}}, and Fe(II)EDTA{sup 2{minus}} on the two sorbents in 0.001 mol/L Ca(ClO{sub 4}){sub 2} to aid in experiment interpretation. It is concluded that cationic radionuclides such as {sup 60}Co or {sup 239/240}Pu, which may be mobilized from disposed wastes by complexation with EDTA{sup 4{minus}}, may become immobilized in groundwater zones where dissimilatory bacterial iron reduction is operative.

  15. Subsurface fluids from basement basalt of the Juan de Fuca Ridge possess microbial communities that are distinct from overlying sediments and surrounding seawater

    NASA Astrophysics Data System (ADS)

    Jungbluth, S.; Bowers, R. M.; Lin, H.; Hsieh, C.; Cowen, J. P.; Rappe, M. S.

    2013-12-01

    Hydrothermal circulation of fluids through the porous and permeable ocean basement fuels a deep subsurface microbial community that remains poorly characterized due to the logistical and methodological constraints associated with sampling the sediment-covered seafloor. Ocean Drilling Program and Integrated Ocean Drilling Program holes penetrating 1.2-3.5 million-years old sediment-covered basaltic crust of the Juan de Fuca Ridge flank fitted with Circulation Obviation Retrofit Kit (CORK) borehole observatories have enabled sampling of chemically-reducing basement fluids over the course of multiple years (2008-2013). Consistent and reliable access to pristine fluids from the ocean crust is due to improvements to CORK observatories, through incorporation of microbiologically-friendly materials, and fluid sampling techniques and equipment. By analyzing ~1.7 million reads of the small subunit ribosomal RNA (SSU rRNA) gene by next-generation Illumina sequencing from marine sediment, deep seawater, and 24 crustal fluid samples spanning multiple years and boreholes (1025C, U1301A, U1362A, and U1362), a distinct subseafloor biosphere dominated by the domain Bacteria was uncovered. Fluids from borehole U1301A sampled annually over the course of three years each had distinct microbial community structure and were dominated by the Proteobacteria. In contrast, fluids from boreholes 1362A and 1362B, located ~500 meters to the northeast, contained lineages phylogenetically related to the phylum Nitrospirae in highest abundance. The domain Archaea was was dominated by either the phylum Crenarchaeota (borehole U1301A) or the Euryarchaeota (boreholes 1025C, U1362A and U1362B). SSU rRNA genes phylogenetically affiliated with known lineages of methane producing Euryarchaeota (e.g. Methanobacteria) were the most abundant archaeal group detected in fluids from Holes U1362A and U1362B, predominantly within samples originating from the deepest subsurface sampling horizon (~200 meters sub

  16. Microbial Community Dynamics in Uranium Contaminated Subsurface Sediments under Biostimulated Conditions with High Nitrate and Nickel Pressure

    SciTech Connect

    Moreels,D.; Crosson, G.; Garafola, C.; Monteleone, D.; Taghavi, S.; Fitts, J.; van der Lelie, D.

    2008-01-01

    The subsurface at the Oak Ridge Field Research Center represents an extreme and diverse geochemical environment that places different stresses on the endogenous microbial communities, including low pH, elevated nitrate concentrations, and the occurrence of heavy metals and radionuclides, including hexavalent uranium [U(VI)]. The in situ immobilization of U(VI) in the aquifer can be achieved through microbial reduction to relatively insoluble U(IV). However, a high redox potential due to the presence of nitrate and the toxicity of heavy metals will impede this process. Our aim is to test biostimulation of the endogenous microbial communities to improve nitrate reduction and subsequent U(VI) reduction under conditions of elevated heavy metals.

  17. Linking specific heterotrophic bacterial populations to bioreduction of uranium and nitrate using stable isotope probing in contaminated subsurface sediments

    SciTech Connect

    Akob, Denise M.; Kerkhof, Lee; Kusel, Kirsten; Watson, David B; Palumbo, Anthony Vito; Kostka, Joel

    2011-01-01

    Shifts in terminal electron-accepting processes during biostimulation of uranium-contaminated sediments were linked to the composition of stimulated microbial populations using DNA-based stable isotope probing. Nitrate reduction preceded U(VI) and Fe(III) reduction in [{sup 13}C]ethanol-amended microcosms. The predominant, active denitrifying microbial groups were identified as members of the Betaproteobacteria, whereas Actinobacteria dominated under metal-reducing conditions.

  18. The Effect of mining and related activities on the sediment-trace element geochemistry of Lake Coeur d'Alene, Idaho, U.S.A.; Part II, Subsurface sediments

    USGS Publications Warehouse

    Horowitz, A.J.; Elrick, K.A.; Robbins, J.A.; Cook, R.B.

    1993-01-01

    During the summer of 1990, 12 gravity cores were collected in Lake Coeur d'Alene, Idaho, at various depths and in a variety of depositional environments. All core subsamples were analyzed to determine bulk chemistry and selected subsamples were analyzed for trace-element partitioning and (137)Cs activity. The purpose of these analyses was to determine the trace-element concentrations and distributions in the sediment column and to try to establish a trace-element geochemical history of the lake in relation to mining and mining-related discharge operations in the area. Substantial portions of the near-surface sediments in Lake Coeur d'Alene are markedly enriched in Ag, As, Cd, Hg, Pb, Sb, and Zn, and somewhat enriched in Cu, Fe, and Mn. Variations in the thickness of the trace element- rich sediments suggest that the source of much of this material is the Coeur d'Alene River. Calculated estimates indicate that there are some 75 million metric tons of trace element-rich sediments currently on/in the lakebed. Estimated trace-element masses in excess of those caused by non-mining-related sources, range from a high of 468,000 metric tons of Pb to a low of 260 metric tons of Hg. The similarity between the trace element-rich surface and subsurface sediments as regards their: (1) location; (2) bulk chemistry; (3) interelement relationships; and (4) trace-element partitioning indicate that the sources and/or concentrating mechanisms causing the trace-element enrichment in the lake probably have been the same throughout their depositional history. Based on Mt. St. Helens' ash layer from the 1980 eruption, ages estimated from (137)Cs activity, and the presence of 80 discernible and presumably annual layers in a core collected near the Coeur d'Alene River delta, it appears that deposition rates for the trace element-rich sediments varied from 2.1 to 1.3 cm/yr. These data also indicate that the deposition of trace element-rich sediments began, at least in the Coeur d

  19. Biogeochemical Coupling of Fe and Tc Speciation in Subsurface Sediments: Implications to Long-Term Tc Immobilization

    SciTech Connect

    Zachara, John M.; Kukkadapu, Ravi K.; Heald, Steve M.; McKinley, James P.; Dohnalkova, Alice C.; Fredrickson, James K.; Byong-Hun Jeon

    2006-04-05

    The overall project has been investigating the reactivity of pertechnetate [Tc(VII)] with Fe(II) forms in model mineral and mineral-microbe systems, and with sediments from the Oak Ridge FRC and the Hanford site. Past project results with Hanford and Oak Ridge sediments have been published in Fredrickson et al., (2004) and Kukkadapu et al., (2006). This poster summarizes a series of model system experiments that investigates whether microbes or biogenic Fe(II) were more important in the reduction of Tc(VII) in an anoxic suspension of ferrihydrite, Shewanella oneidensis MR-1, Tc(VII), and electron donor. Ferrihydrite is used to represent a bioavailable Fe(III) oxide present in small amounts in Oak Ridge and Hanford sediments. In order to address this overall goal, Tc(VII) reduction rates and redox products were studied in less complex systems where individual abiotic and biotic reactions were isolated for rigorous characterization. The specific objectives of the individual experiments in the series were as follows: (1) Identify the rates and products of the reaction of Tc(VII) with aqueous Fe(II) at circumneutral pH values (homogeneous reduction). (2) Identify the rates and products of the reaction of Tc(VII) with surface complexed Fe(II) on goethite and hematite in the circumneutral pH range (heterogeneous reduction). (3) Identify the rates and products of the reaction of Tc(VII) with MR-1 under anoxic conditions individually with hydrogen and lactate as electron donors (biologic reduction). (4) Use insights from the above experiments to determine which of the three above, potentially parallel reactions determine the final speciation of Tc in a mixture of ferrihydrite, respiring MR-1, and Tc(VII).

  20. DOE ER63951-3 Final Report: An Integrated Assessment of Geochemical and Community Structure Determinants of Metal Reduction Rates in Subsurface Sediments

    SciTech Connect

    Susan Pfiffner

    2010-06-28

    The objective of this research was to examine the importance of microbial community structure in influencing uranium reduction rates in subsurface sediments. If the redox state alone is the key to metal reduction, then any organisms that can utilize the oxygen and nitrate in the subsurface can change the geochemical conditions so metal reduction becomes an energetically favored reaction. Thus, community structure would not be critical in determining rates or extent of metal reduction unless community structure influenced the rate of change in redox. Alternatively, some microbes may directly catalyze metal reduction (e.g., specifically reduce U). In this case the composition of the community may be more important and specific types of electron donors may promote the production of communities that are more adept at U reduction. Our results helped determine if the type of electron donor or the preexisting community is important in the bioremediation of metal-contaminated environments subjected to biostimulation. In a series of experiments at the DOE FRC site in Oak Ridge we have consistently shown that all substrates promoted nitrate reduction, while glucose, ethanol, and acetate always promoted U reduction. Methanol only occasionally promoted extensive U reduction which is possibly due to community heterogeneity. There appeared to be limitations imposed on the community related to some substrates (e.g. methanol and pyruvate). Membrane lipid analyses (phospholipids and respiratory quinones) indicated different communities depending on electron donor used. Terminal restriction fragment length polymorphism and clone libraries indicated distinct differences among communities even in treatments that promoted U reduction. Thus, there was enough metabolic diversity to accommodate many different electron donors resulting in the U bioimmobilization.

  1. The effect of biogenic Fe(II) on the stability and sorption of Co(II)EDTA 2- to goethite and a subsurface sediment

    NASA Astrophysics Data System (ADS)

    Zachara, John M.; Smith, Steven C.; Fredrickson, James K.

    2000-04-01

    Laboratory experiments were conducted with suspensions of goethite (α-FeOOH) and a subsurface sediment to assess the influence of bacterial iron reduction on the fate of Co(II)EDTA 2-, a representative metal-ligand complex of intermediate stability (log K Co(II)EDTA = 17.97). The goethite was synthetic (ca. 55 m 2/g) and the sediment was a Pleistocene age, Fe(III) oxide-containing material from the Atlantic coastal plain (Milford). Shewanella alga strain BrY, a dissimilatory iron reducing bacterium (DIRB), was used to promote Fe(III) oxide reduction. Sorption isotherms and pH adsorption edges were measured for Co 2+, Fe 2+, Co(II)EDTA 2-, and Fe(II)EDTA 2- on the two sorbents in 0.001 mol/L Ca(ClO 4) 2 to aid in experiment interpretation. Anoxic suspensions of the sorbents in PIPES buffer at pH 6.5-7.0 were spiked with Co(II)EDTA 2- (10 -5 mol/L, 60Co and 14EDTA labeled), inoculated with BrY (1-6 × 10 8 organisms/mL), and the headspace filled with a N 2/H 2 gas mix. The experiments were conducted under non-growth conditions. The medium did not contain PO 43- (with one exception), trace elements, or vitamins. The tubes were incubated under anoxic conditions at 25°C for time periods in excess of 100 d. Replicate tubes were sacrificed and analyzed at desired time periods for pH, Fe(II) TOT, Fe (aq)2+, 60Co, and 14EDTA. Abiotic analogue experiments were conducted where Fe (aq)2+ was added in increasing concentration to Co(II)EDTA 2-/mineral suspensions to simulate the influence of bacterial Fe(II) evolution. The DIRB generated Fe(II) from both goethite and the Milford sediment that was strongly sorbed by mineral surfaces. Aqueous Fe 2+ increased during the experiment as surfaces became saturated; Fe (aq)2+ induced the dissociation of Co(II)EDTA 2- into a mixture of Co 2+, Co(II)EDTA 2-, and Fe(II)EDTA 2- (log K Fe(II)EDTA = 15.98). The extent of dissociation of Co(II)EDTA 2- was greater in the subsurface sediment because it sorbed Fe(II) less strongly than did

  2. Deep subsurface microbial processes

    USGS Publications Warehouse

    Lovley, D.R.; Chapelle, F.H.

    1995-01-01

    Information on the microbiology of the deep subsurface is necessary in order to understand the factors controlling the rate and extent of the microbially catalyzed redox reactions that influence the geophysical properties of these environments. Furthermore, there is an increasing threat that deep aquifers, an important drinking water resource, may be contaminated by man's activities, and there is a need to predict the extent to which microbial activity may remediate such contamination. Metabolically active microorganisms can be recovered from a diversity of deep subsurface environments. The available evidence suggests that these microorganisms are responsible for catalyzing the oxidation of organic matter coupled to a variety of electron acceptors just as microorganisms do in surface sediments, but at much slower rates. The technical difficulties in aseptically sampling deep subsurface sediments and the fact that microbial processes in laboratory incubations of deep subsurface material often do not mimic in situ processes frequently necessitate that microbial activity in the deep subsurface be inferred through nonmicrobiological analyses of ground water. These approaches include measurements of dissolved H2, which can predict the predominant microbially catalyzed redox reactions in aquifers, as well as geochemical and groundwater flow modeling, which can be used to estimate the rates of microbial processes. Microorganisms recovered from the deep subsurface have the potential to affect the fate of toxic organics and inorganic contaminants in groundwater. Microbial activity also greatly influences 1 the chemistry of many pristine groundwaters and contributes to such phenomena as porosity development in carbonate aquifers, accumulation of undesirably high concentrations of dissolved iron, and production of methane and hydrogen sulfide. Although the last decade has seen a dramatic increase in interest in deep subsurface microbiology, in comparison with the study of

  3. Keep your Sox on: Community genomics-directed isolation and microscopic characterization of the dominant subsurface sulfur-oxidizing bacterium in a sediment aquifer

    NASA Astrophysics Data System (ADS)

    Mullin, S. W.; Wrighton, K. C.; Luef, B.; Wilkins, M. J.; Handley, K. M.; Williams, K. H.; Banfield, J. F.

    2012-12-01

    Community genomics and proteomics (proteogenomics) can be used to predict the metabolic potential of complex microbial communities and provide insight into microbial activity and nutrient cycling in situ. Inferences regarding the physiology of specific organisms then can guide isolation efforts, which, if successful, can yield strains that can be metabolically and structurally characterized to further test metagenomic predictions. Here we used proteogenomic data from an acetate-stimulated, sulfidic sediment column deployed in a groundwater well in Rifle, CO to direct laboratory amendment experiments to isolate a bacterial strain potentially involved in sulfur oxidation for physiological and microscopic characterization (Handley et al, submitted 2012). Field strains of Sulfurovum (genome r9c2) were predicted to be capable of CO2 fixation via the reverse TCA cycle and sulfur oxidation (Sox and SQR) coupled to either nitrate reduction (Nap, Nir, Nos) in anaerobic environments or oxygen reduction in microaerobic (cbb3 and bd oxidases) environments; however, key genes for sulfur oxidation (soxXAB) were not identified. Sulfidic groundwater and sediment from the Rifle site were used to inoculate cultures that contained various sulfur species, with and without nitrate and oxygen. We isolated a bacterium, Sulfurovum sp. OBA, whose 16S rRNA gene shares 99.8 % identity to the gene of the dominant genomically characterized strain (genome r9c2) in the Rifle sediment column. The 16S rRNA gene of the isolate most closely matches (95 % sequence identity) the gene of Sulfurovum sp. NBC37-1, a genome-sequenced deep-sea sulfur oxidizer. Strain OBA grew via polysulfide, colloidal sulfur, and tetrathionate oxidation coupled to nitrate reduction under autotrophic and mixotrophic conditions. Strain OBA also grew heterotrophically, oxidizing glucose, fructose, mannose, and maltose with nitrate as an electron acceptor. Over the range of oxygen concentrations tested, strain OBA was not

  4. Characteristics of the surface-subsurface flow generation and sediment yield to the rainfall regime and land-cover by long-term in-situ observation in the red soil region, Southern China

    NASA Astrophysics Data System (ADS)

    Liu, Yao-Jun; Yang, Jie; Hu, Jian-Min; Tang, Chong-Jun; Zheng, Hai-Jin

    2016-08-01

    Land cover and rainfall regime are two important factors that affect soil erosion. In this paper, three land cover types - grass cover, litter cover and bare land - were employed to analyze surface runoff, subsurface flow and sediment loss processes in relation to the rainfall regimes in the red soil region of China. Five rainfall regimes were classified according to 393 rainfall events via a k-means clustering method based on the rainfall depth, duration and maximum 30-min intensity. The highest surface runoff coefficient and erosion amount were found on bare land in all five rainfall regimes, and the lowest were found on grass cover. The litter cover generated the highest subsurface flow rate, followed by the grass cover; the lowest was on bare land. For grass cover and litter cover plots, rainfall events of rainfall regime IV which had the longest duration, greatest depth and lowest intensity had the highest surface runoff coefficient, soil erosion amount and subsurface flow rate. For bare land, storm rainfall events of rainfall regime V had the highest intensity, lowest depth and duration, had the highest surface runoff coefficient and soil erosion amount, but the lowest subsurface flow rate. The highest subsurface flow rate of bare land happened in rainfall regime IV. Surface cover was urgently needed to reduce soil erosion. When the lands under dense surface cover, more attention should be paid to rainfall events that of long duration, high depth but low in intensity which commonly occurred in spring. The interactions of surface-subsurface flow and its effects on soil erosion and nutrient loss were worth considering in the red soil region.

  5. Terrestrial Subsurface Ecosystem

    SciTech Connect

    Wilkins, Michael J.; Fredrickson, Jim K.

    2015-10-15

    The Earth’s crust is a solid cool layer that overlays the mantle, with a varying thickness of between 30-50 km on continental plates, and 5-10 km on oceanic plates. Continental crust is composed of a variety of igneous, metamorphic, and sedimentary rocks that weather and re-form over geologic cycles lasting millions to billions of years. At the crust surface, these weathered minerals and organic material combine to produce a variety of soils types that provide suitable habitats and niches for abundant microbial diversity (see Chapter 4). Beneath this soil zone is the subsurface. Once thought to be relatively free of microorganisms, recent estimates have calculated that between 1016-1017 g C biomass (2-19% of Earth’s total biomass) may be present in this environment (Whitman et al., 1998;McMahon and Parnell, 2014). Microbial life in the subsurface exists across a wide range of habitats: in pores associated with relatively shallow unconsolidated aquifer sediments to fractures in bedrock formations that are more than a kilometer deep, where extreme lithostatic pressures and temperatures are encountered. While these different environments contain varying physical and chemical conditions, the absence of light is a constant. Despite this, diverse physiologies and metabolisms enable microorganisms to harness energy and carbon for growth in water-filled pore spaces and fractures. Carbon and other element cycles are driven by microbial activity, which has implications for both natural processes and human activities in the subsurface, e.g., bacteria play key roles in both hydrocarbon formation and degradation. Hydrocarbons are a major focus for human utilization of the subsurface, via oil and gas extraction and potential geologic CO2 sequestration. The subsurface is also utilized or being considered for sequestered storage of high-level radioactive waste from nuclear power generation and residual waste from past production of weapons grade nuclear materials. While our

  6. Subsurface sounders

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Airborne or spaceborne electromagnetic systems used to detect subsurface features are discussed. Data are given as a function of resistivity of ground material, magnetic permeability of free space, and angular frequency. It was noted that resistivities vary with the water content and temperature.

  7. An improved cell separation technique for marine subsurface sediments: applications for high-throughput analysis using flow cytometry and cell sorting.

    PubMed

    Morono, Yuki; Terada, Takeshi; Kallmeyer, Jens; Inagaki, Fumio

    2013-10-01

    Development of an improved technique for separating microbial cells from marine sediments and standardization of a high-throughput and discriminative cell enumeration method were conducted. We separated microbial cells from various types of marine sediment and then recovered the cells using multilayer density gradients of sodium polytungstate and/or Nycodenz, resulting in a notably higher percent recovery of cells than previous methods. The efficiency of cell extraction generally depends on the sediment depth; using the new technique we developed, more than 80% of the total cells were recovered from shallow sediment samples (down to 100 meters in depth), whereas ~50% of cells were recovered from deep samples (100-365 m in depth). The separated cells could be rapidly enumerated using flow cytometry (FCM). The data were in good agreement with those obtained from manual microscopic direct counts over the range 10(4)-10(8) cells cm(-3). We also demonstrated that sedimentary microbial cells can be efficiently collected using a cell sorter. The combined use of our new cell separation and FCM/cell sorting techniques facilitates high-throughput and precise enumeration of microbial cells in sediments and is amenable to various types of single-cell analyses, thereby enhancing our understanding of microbial life in the largely uncharacterized deep subseafloor biosphere. PMID:23731283

  8. Environmental factors affecting distribution and abundance of bacteria, fungi and protozoa in subsurface sediments of the Upper Atlantic Coastal Plain, USA

    SciTech Connect

    Levine, S.N.; Ghiorse, W.C.

    1990-01-01

    Exploratory statistical analyses of microbiological, hydrological and geochemical data for samples from four boreholes drilled into Upper Atlantic Coastal Plain sediments near the Savannah River Site, SC, showed highly significant correlations between bacterial abundance (AODC and CFU) and hydraulic conductivity (K). Sediment texture variables (% sand (S), % silt, % clay (C), and S/C) were strongly interrelated with K and, therefore, also correlated with bacterial abundance. AODC did not correlate with the concentrations of dissolved inorganic nitrogen (DIN) or dissolved organic carbon (DOC) in pore water. CFU also did not correlate with DIN, but a negative relationship was found between the CFU and DOC for sandy sediments, suggesting that microbial activity may control pore water DOC concentration. In some, but not all boreholes, AODC and CFU correlated negatively with pore water concentrations of metals and positively with pH. Protozoan abundance correlated strongly with AODC and CFU in the two boreholes closest to the recharge areas for their major aquifers. It also correlated with sediment texture variables, but not with K. Fungal abundance did not correlate with the abundance of other microbial types when data from individual boreholes were considered; however it did correlate with both bacterial and protozoan abundance when data from all four boreholes were combined. There was no relationship between fungal abundance and either K or sediment texture.

  9. Environmental factors affecting distribution and abundance of bacteria, fungi and protozoa in subsurface sediments of the Upper Atlantic Coastal Plain, USA

    SciTech Connect

    Levine, S.N.; Ghiorse, W.C.

    1990-12-31

    Exploratory statistical analyses of microbiological, hydrological and geochemical data for samples from four boreholes drilled into Upper Atlantic Coastal Plain sediments near the Savannah River Site, SC, showed highly significant correlations between bacterial abundance (AODC and CFU) and hydraulic conductivity (K). Sediment texture variables (% sand (S), % silt, % clay (C), and S/C) were strongly interrelated with K and, therefore, also correlated with bacterial abundance. AODC did not correlate with the concentrations of dissolved inorganic nitrogen (DIN) or dissolved organic carbon (DOC) in pore water. CFU also did not correlate with DIN, but a negative relationship was found between the CFU and DOC for sandy sediments, suggesting that microbial activity may control pore water DOC concentration. In some, but not all boreholes, AODC and CFU correlated negatively with pore water concentrations of metals and positively with pH. Protozoan abundance correlated strongly with AODC and CFU in the two boreholes closest to the recharge areas for their major aquifers. It also correlated with sediment texture variables, but not with K. Fungal abundance did not correlate with the abundance of other microbial types when data from individual boreholes were considered; however it did correlate with both bacterial and protozoan abundance when data from all four boreholes were combined. There was no relationship between fungal abundance and either K or sediment texture.

  10. An improved cell separation technique for marine subsurface sediments: applications for high-throughput analysis using flow cytometry and cell sorting

    PubMed Central

    Morono, Yuki; Terada, Takeshi; Kallmeyer, Jens; Inagaki, Fumio

    2013-01-01

    Summary Development of an improved technique for separating microbial cells from marine sediments and standardization of a high-throughput and discriminative cell enumeration method were conducted. We separated microbial cells from various types of marine sediment and then recovered the cells using multilayer density gradients of sodium polytungstate and/or Nycodenz, resulting in a notably higher percent recovery of cells than previous methods. The efficiency of cell extraction generally depends on the sediment depth; using the new technique we developed, more than 80% of the total cells were recovered from shallow sediment samples (down to 100 meters in depth), whereas ∼ 50% of cells were recovered from deep samples (100–365 m in depth). The separated cells could be rapidly enumerated using flow cytometry (FCM). The data were in good agreement with those obtained from manual microscopic direct counts over the range 104–108 cells cm−3. We also demonstrated that sedimentary microbial cells can be efficiently collected using a cell sorter. The combined use of our new cell separation and FCM/cell sorting techniques facilitates high-throughput and precise enumeration of microbial cells in sediments and is amenable to various types of single-cell analyses, thereby enhancing our understanding of microbial life in the largely uncharacterized deep subseafloor biosphere. PMID:23731283

  11. Mineralogic Residence and Desorption Rates of Sorbed 90Sr in Contaminated Subsurface Sediments: Implications to Future Behavior and In-Ground Stability

    SciTech Connect

    Peter C. Lichtner

    2006-06-01

    90Sr desorption process will be quantified in coarse-textured Hanford sediments contaminated by different waste types and a reaction-based reactive transport model developed to forecast 90Sr concentration dynamics in Hanford's 100-N plume. Previous research has addressed 137Cs desorption from HLW-contaminated sediment providing results critical for HLW tank farm closure decisions. This renewal focuses on 90Sr with the objective of providing fundamental knowledge to predict future in-ground behavior as required for sound remedial decisions. Preliminary observations that suggest that 10-y sorbed 90Sr in coarse-textured sediment resides in the interiors of basaltic lithic fragments. This intraparticle retention defines a new conceptual model for 90Sr retardation that is tentatively attributed to internal domains of phyllosilicates formed from the weathering of basaltic glass. Research will characterize the spatial locations, composition, and reactivity of these intragrain phyllosilicate domains using spectroscopic, microscopic, and wet chemical methods. Intragrain porosity, diffusivity, and tortuosity will be estimated using emersion experiments coupled with particle imaging (using electron, X-ray, and NMR techniques). Desorption rates and extent will be measured from contaminated Hanford sediments of different waste impact in electrolytes that promote isotopic exchange, ion exchange, and/or dissolution. Desorption results will be interpreted with a geochemical-physical model that incorporates aqueous speciation, mass transfer, and other important factors. Batch and column experiments will be performed with sediments from Hanfords 100-N plume to quantify factors controlling long-term release rates and river stage effects. Newfound understanding and geochemical parameters will be incorporated into the FLOTRAN reactive transport code for simulation of 100-N plume dynamics.

  12. Linking Specific Heterotrophic Bacterial Populations to Bioreduction of Uranium and Nitrate in Contaminated Subsurface Sediments by Using Stable Isotope Probing▿†

    PubMed Central

    Akob, Denise M.; Kerkhof, Lee; Küsel, Kirsten; Watson, David B.; Palumbo, Anthony V.; Kostka, Joel E.

    2011-01-01

    Shifts in terminal electron-accepting processes during biostimulation of uranium-contaminated sediments were linked to the composition of stimulated microbial populations using DNA-based stable isotope probing. Nitrate reduction preceded U(VI) and Fe(III) reduction in [13C]ethanol-amended microcosms. The predominant, active denitrifying microbial groups were identified as members of the Betaproteobacteria, whereas Actinobacteria dominated under metal-reducing conditions. PMID:21948831

  13. Marine subsurface eukaryotes: the fungal majority.

    PubMed

    Edgcomb, Virginia P; Beaudoin, David; Gast, Rebecca; Biddle, Jennifer F; Teske, Andreas

    2011-01-01

    Studies on the microbial communities of deep subsurface sediments have indicated the presence of Bacteria and Archaea throughout the sediment column. Microbial eukaryotes could also be present in deep-sea subsurface sediments; either bacterivorous protists or eukaryotes capable of assimilating buried organic carbon. DNA- and RNA-based clone library analyses are used here to examine the microbial eukaryotic diversity and identify the potentially active members in deep-sea sediment cores of the Peru Margin and the Peru Trench. We compared surface communities with those much deeper in the same cores, and compared cores from different sites. Fungal sequences were most often recovered from both DNA- and RNA-based clone libraries, with variable overall abundances of different sequence types and different dominant clone types in the RNA-based and the DNA-based libraries. Surficial sediment communities were different from each other and from the deep subsurface samples. Some fungal sequences represented potentially novel organisms as well as ones with a cosmopolitan distribution in terrestrial, fresh and salt water environments. Our results indicate that fungi are the most consistently detected eukaryotes in the marine sedimentary subsurface; further, some species may be specifically adapted to the deep subsurface and may play important roles in the utilization and recycling of nutrients.

  14. Rudimentary Cleaning Compared to Level 300A

    NASA Technical Reports Server (NTRS)

    Arpin, Christina Y. Pina; Stoltzfus, Joel

    2012-01-01

    A study was done to characterize the cleanliness level achievable when using a rudimentary cleaning process, and results were compared to JPR 5322.1G Level 300A. While it is not ideal to clean in a shop environment, some situations (e.g., field combat operations) require oxygen system hardware to be maintained and cleaned to prevent a fire hazard, even though it cannot be sent back to a precision cleaning facility. This study measured the effectiveness of basic shop cleaning. Initially, three items representing parts of an oxygen system were contaminated: a metal plate, valve body, and metal oxygen bottle. The contaminants chosen were those most likely to be introduced to the system during normal use: oil, lubricant, metal shavings/powder, sand, fingerprints, tape, lip balm, and hand lotion. The cleaning process used hot water, soap, various brushes, gaseous nitrogen, water nozzle, plastic trays, scouring pads, and a controlled shop environment. Test subjects were classified into three groups: technical professionals having an appreciation for oxygen hazards; professional precision cleaners; and a group with no previous professional knowledge of oxygen or precision cleaning. Three test subjects were in each group, and each was provided with standard cleaning equipment, a cleaning procedure, and one of each of the three test items to clean. The results indicated that the achievable cleanliness level was independent of the technical knowledge or proficiency of the personnel cleaning the items. Results also showed that achieving a Level 300 particle count was more difficult than achieving a Level A nonvolatile residue amount.

  15. 21 CFR 520.300a - Cambendazole suspension.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Cambendazole suspension. 520.300a Section 520.300a Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.300a Cambendazole...

  16. 21 CFR 520.300a - Cambendazole suspension.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Cambendazole suspension. 520.300a Section 520.300a Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.300a Cambendazole...

  17. Isolation, Characterization, and U(VI)-Reducing Potential of a Facultatively Anaerobic, Acid-Resistant Bacterium from Low-pH, Nitrate- and U(VI)-Contaminated Subsurface Sediment and Description of Salmonella subterranea sp. nov.

    PubMed Central

    Shelobolina, Evgenya S.; Sullivan, Sara A.; O'Neill, Kathleen R.; Nevin, Kelly P.; Lovley, Derek R.

    2004-01-01

    A facultatively anaerobic, acid-resistant bacterium, designated strain FRCl, was isolated from a low-pH, nitrate- and U(VI)-contaminated subsurface sediment at site FW-024 at the Natural and Accelerated Bioremediation Research Field Research Center in Oak Ridge, Tenn. Strain FRCl was enriched at pH 4.5 in minimal medium with nitrate as the electron acceptor, hydrogen as the electron donor, and acetate as the carbon source. Clones with 16S ribosomal DNA (rDNA) sequences identical to the sequence of strain FRCl were also detected in a U(VI)-reducing enrichment culture derived from the same sediment. Cells of strain FRCl were gram-negative motile regular rods 2.0 to 3.4 μm long and 0.7 to 0.9 μm in diameter. Strain FRCl was positive for indole production, by the methyl red test, and for ornithine decarboxylase; it was negative by the Voges-Proskauer test (for acetylmethylcarbinol production), for urea hydrolysis, for arginine dihydrolase, for lysine decarboxylase, for phenylalanine deaminase, for H2S production, and for gelatin hydrolysis. Strain FRCl was capable of using O2, NO3−, S2O32−, fumarate, and malate as terminal electron acceptors and of reducing U(VI) in the cell suspension. Analysis of the 16S rDNA sequence of the isolate indicated that this strain was 96.4% similar to Salmonella bongori and 96.3% similar to Enterobacter cloacae. Physiological and phylogenetic analyses suggested that strain FRCl belongs to the genus Salmonella and represents a new species, Salmonella subterranea sp. nov. PMID:15128557

  18. Microscale geochemical gradients in Hanford 300 Area sediment biofilms and influence of uranium

    SciTech Connect

    Nguyen, Hung D.; Cao, Bin; Mishra, Bhoopesh; Boyanov, Maxim I.; Kemner, Kenneth M.; Fredrickson, Jim K.; Beyenal, Haluk

    2012-01-01

    The presence and importance of microenvironments in the subsurface at contaminated sites were suggested by previous geochemical studies. However, no direct quantitative characterization of the geochemical microenvironments had been reported. We quantitatively characterized microscale geochemical gradients (dissolved oxygen (DO), H(2), pH, and redox potential) in Hanford 300A subsurface sediment biofilms. Our results revealed significant differences in geochemical parameters across the sediment biofilm/water interface in the presence and absence of U(VI) under oxic and anoxic conditions. While the pH was relatively constant within the sediment biofilm, the redox potential and the DO and H(2) concentrations were heterogeneous at the microscale (<500-1000 μm). We found microenvironments with high DO levels (DO hotspots) when the sediment biofilm was exposed to U(VI). On the other hand, we found hotspots (high concentrations) of H(2) under anoxic conditions both in the presence and in the absence of U(VI). The presence of anoxic microenvironments inside the sediment biofilms suggests that U(VI) reduction proceeds under bulk oxic conditions. To test this, we operated our biofilm reactor under air-saturated conditions in the presence of U(VI) and characterized U speciation in the sediment biofilm. U L(III)-edge X-ray absorption spectroscopy (XANES and EXAFS) showed that 80-85% of the U was in the U(IV) valence state.

  19. Complete genome sequence of Anaeromyxobacter sp. Fw109-5, an Anaerobic, Metal-Reducing Bacterium Isolated from a Contaminated Subsurface Environment

    SciTech Connect

    Hwang, C.; Copeland, A.; Lucas, Susan; Lapidus, Alla; Barry, Kerrie W.; Glavina del Rio, T.; Dalin, Eileen; Tice, Hope; Pitluck, S.; Sims, David R.; Brettin, T.; Bruce, David; Detter, J. C.; Han, Cliff F.; Schmutz, Jeremy; Larimer, F.; Land, M.; Hauser, L.; Kyrpides, Nikos C.; Lykidis, Athanasios; Richardson, P. M.; Beliaev, Alex S.; Sanford, Robert A.; Loeffler, Frank E.; Fields, Matthew W.

    2015-01-22

    We report the genome sequence of Anaeromyxobacter sp. Fw109-5, isolated from nitrate- and uranium-contaminated subsurface sediment of the Oak Ridge Integrated Field-Scale Subsurface Research Challenge (IFC) site, Oak Ridge Reservation, TN. The bacterium’s genome sequence will elucidate its physiological potential in subsurface sediments undergoing in situ uranium bioremediation and natural attenuation.

  20. LeCroy MQT300A - charge to time converter

    SciTech Connect

    Yamrone, B.; Roberts, K.; Kelly, J.

    1997-12-31

    The MQT300A was developed to offer high resolution (12 bit) and wide dynamic range (18 bit) with reasonable cost, high density and fast conversion time (< 10 {mu}s). The reduced conversion time has allowed its first users the option to choose whether or not to develop a fast clear strategy as part of their trigger system. It can also be used for chamber-mounted applications allowing compact digital data cabling to the remote TDC. The MQT300A is a custom development produced in collaboration with the BELLE collaboration at KEK and the CLEO group at Cornell. In this collaboration Cornell and KEK were partners with LeCroy in both the specification and evaluation of the first prototypes. LeCroy has been responsible for the remainder of the project. The MQT300A is available in LeCroy modules and also as a separate monolithic. The MQT300A was designed to take advantage of the latest generation of multi-hit TDCs, for example the LeCroy 1877S FASTBUS ADC. The 1877S was specifically optimized to improve conversion time and to intelligently minimize the data record size for the MQT300A application. A prototype part was designed and fabricated using a custom bipolar process. Though fully functional it did not meet several important performance specifications. A reiteration with significant redesign of two sections resulted in a part that meets all specifications. The unique encoding algorithm used to provide auto-ranging has had a U.S. patent allowed. The part is now commercially available in production volumes.

  1. Ceramic subsurface marker prototypes

    SciTech Connect

    Lukens, C.E.

    1985-05-02

    The client submitted 5 sets of porcelain and stoneware subsurface (radioactive site) marker prototypes (31 markers each set). The following were determined: compressive strength, thermal shock resistance, thermal crazing resistance, alkali resistance, color retention, and chemical resistance.

  2. Subsurface Microbiology and Biogeochemistry

    SciTech Connect

    Fredrickson, Jim K.; Fletcher, Madilyn

    2001-05-01

    Jim contributed a chapter to this book, in addition to co-editing it with Madilyn Fletcher. Fredrickson, J. K., and M. Fletcher. (eds.) 2001 Subsurface Microbiology and Biogeochemistry. Wiley-Liss, Inc., New York.

  3. Electrical Subsurface Grounding Analysis

    SciTech Connect

    J.M. Calle

    2000-11-01

    The purpose and objective of this analysis is to determine the present grounding requirements of the Exploratory Studies Facility (ESF) subsurface electrical system and to verify that the actual grounding system and devices satisfy the requirements.

  4. Site Recommendation Subsurface Layout

    SciTech Connect

    C.L. Linden

    2000-06-28

    The purpose of this analysis is to develop a Subsurface Facility layout that is capable of accommodating the statutory capacity of 70,000 metric tons of uranium (MTU), as well as an option to expand the inventory capacity, if authorized, to 97,000 MTU. The layout configuration also requires a degree of flexibility to accommodate potential changes in site conditions or program requirements. The objective of this analysis is to provide a conceptual design of the Subsurface Facility sufficient to support the development of the Subsurface Facility System Description Document (CRWMS M&O 2000e) and the ''Emplacement Drift System Description Document'' (CRWMS M&O 2000i). As well, this analysis provides input to the Site Recommendation Consideration Report. The scope of this analysis includes: (1) Evaluation of the existing facilities and their integration into the Subsurface Facility design. (2) Identification and incorporation of factors influencing Subsurface Facility design, such as geological constraints, thermal loading, constructibility, subsurface ventilation, drainage control, radiological considerations, and the Test and Evaluation Facilities. (3) Development of a layout showing an available area in the primary area sufficient to support both the waste inventories and individual layouts showing the emplacement area required for 70,000 MTU and, if authorized, 97,000 MTU.

  5. Subsurface Contamination Control

    SciTech Connect

    Y. Yuan

    2001-12-12

    There are two objectives of this report, ''Subsurface Contamination Control''. The first is to provide a technical basis for recommending limiting radioactive contamination levels (LRCL) on the external surfaces of waste packages (WP) for acceptance into the subsurface repository. The second is to provide an evaluation of the magnitude of potential releases from a defective WP and the detectability of the released contents. The technical basis for deriving LRCL has been established in ''Retrieval Equipment and Strategy for Wp on Pallet'' (CRWMS M and O 2000g, 6.3.1). This report updates the derivation by incorporating the latest design information of the subsurface repository for site recommendation. The derived LRCL on the external surface of WPs, therefore, supercede that described in CRWMS M and O 2000g. The derived LRCL represent the average concentrations of contamination on the external surfaces of each WP that must not be exceeded before the WP is to be transported to the subsurface facility for emplacement. The evaluation of potential releases is necessary to control the potential contamination of the subsurface repository and to detect prematurely failed WPs. The detection of failed WPs is required in order to provide reasonable assurance that the integrity of each WP is intact prior to MGR closure. An emplaced WP may become breached due to manufacturing defects or improper weld combined with failure to detect the defect, by corrosion, or by mechanical penetration due to accidents or rockfall conditions. The breached WP may release its gaseous and volatile radionuclide content to the subsurface environment and result in contaminating the subsurface facility. The scope of this analysis is limited to radioactive contaminants resulting from breached WPs during the preclosure period of the subsurface repository. This report: (1) documents a method for deriving LRCL on the external surfaces of WP for acceptance into the subsurface repository; (2) provides a

  6. Subsurface Contamination Control

    SciTech Connect

    Y. Yuan

    2001-11-16

    There are two objectives of this report, ''Subsurface Contamination Control''. The first is to provide a technical basis for recommending limiting radioactive contamination levels (LRCL) on the external surfaces of waste packages (WP) for acceptance into the subsurface repository. The second is to provide an evaluation of the magnitude of potential releases from a defective WP and the detectability of the released contents. The technical basis for deriving LRCL has been established in ''Retrieval Equipment and Strategy for Wp on Pallet'' (CRWMS M and O 2000g, 6.3.1). This report updates the derivation by incorporating the latest design information of the subsurface repository for site recommendation. The derived LRCL on the external surface of WPs, therefore, supercede that described in CRWMS M and O 2000g. The derived LRCL represent the average concentrations of contamination on the external surfaces of each WP that must not be exceeded before the WP is to be transported to the subsurface facility for emplacement. The evaluation of potential releases is necessary to control the potential contamination of the subsurface repository and to detect prematurely failed WPs. The detection of failed WPs is required in order to provide reasonable assurance that the integrity of each WP is intact prior to MGR closure. An emplaced WP may become breached due to manufacturing defects or improper weld combined with failure to detect the defect, by corrosion, or by mechanical penetration due to accidents or rockfall conditions. The breached WP may release its gaseous and volatile radionuclide content to the subsurface environment and result in contaminating the subsurface facility. The scope of this analysis is limited to radioactive contaminants resulting from breached WPs during the preclosure period of the subsurface repository. This report: (1) documents a method for deriving LRCL on the external surfaces of WP for acceptance into the subsurface repository; (2) provides a

  7. 17 CFR 301.300a - Form 300-A, for summary of buy-ins or sell-outs of all open contractual commitments.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Form 300-A, see the List of CFR Sections Affected, which appears in the Finding Aids section of the... 17 Commodity and Securities Exchanges 3 2013-04-01 2013-04-01 false Form 300-A, for summary of buy... Form 300-A, for summary of buy-ins or sell-outs of all open contractual commitments. This form shall...

  8. 17 CFR 301.300a - Form 300-A, for summary of buy-ins or sell-outs of all open contractual commitments.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Form 300-A, see the List of CFR Sections Affected, which appears in the Finding Aids section of the... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Form 300-A, for summary of buy... Form 300-A, for summary of buy-ins or sell-outs of all open contractual commitments. This form shall...

  9. 17 CFR 301.300a - Form 300-A, for summary of buy-ins or sell-outs of all open contractual commitments.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Form 300-A, see the List of CFR Sections Affected, which appears in the Finding Aids section of the... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Form 300-A, for summary of buy... Form 300-A, for summary of buy-ins or sell-outs of all open contractual commitments. This form shall...

  10. 17 CFR 301.300a - Form 300-A, for summary of buy-ins or sell-outs of all open contractual commitments.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Form 300-A, see the List of CFR Sections Affected, which appears in the Finding Aids section of the... 17 Commodity and Securities Exchanges 3 2012-04-01 2012-04-01 false Form 300-A, for summary of buy... Form 300-A, for summary of buy-ins or sell-outs of all open contractual commitments. This form shall...

  11. 17 CFR 301.300a - Form 300-A, for summary of buy-ins or sell-outs of all open contractual commitments.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Form 300-A, see the List of CFR Sections Affected, which appears in the Finding Aids section of the... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Form 300-A, for summary of buy... Form 300-A, for summary of buy-ins or sell-outs of all open contractual commitments. This form shall...

  12. Best Practice -- Subsurface Investigations

    SciTech Connect

    Clark Scott

    2010-03-01

    These best practices for Subsurface Survey processes were developed at the Idaho National Laboratory (INL) and later shared and formalized by a sub-committee, under the Electrical Safety Committee of EFCOG. The developed best practice is best characterized as a Tier II (enhanced) survey process for subsurface investigations. A result of this process has been an increase in the safety and lowering of overall cost, when utility hits and their related costs are factored in. The process involves improving the methodology and thoroughness of the survey and reporting processes; or improvement in tool use rather than in the tools themselves. It is hoped that the process described here can be implemented at other sites seeking to improve their Subsurface Investigation results with little upheaval to their existing system.

  13. The Serpentinite Subsurface Microbiome

    NASA Astrophysics Data System (ADS)

    Schrenk, M. O.; Nelson, B. Y.; Brazelton, W. J.

    2011-12-01

    Microbial habitats hosted in ultramafic rocks constitute substantial, globally-distributed portions of the subsurface biosphere, occurring both on the continents and beneath the seafloor. The aqueous alteration of ultramafics, in a process known as serpentinization, creates energy rich, high pH conditions, with low concentrations of inorganic carbon which place fundamental constraints upon microbial metabolism and physiology. Despite their importance, very few studies have attempted to directly access and quantify microbial activities and distributions in the serpentinite subsurface microbiome. We have initiated microbiological studies of subsurface seeps and rocks at three separate continental sites of serpentinization in Newfoundland, Italy, and California and compared these results to previous analyses of the Lost City field, near the Mid-Atlantic Ridge. In all cases, microbial cell densities in seep fluids are extremely low, ranging from approximately 100,000 to less than 1,000 cells per milliliter. Culture-independent analyses of 16S rRNA genes revealed low-diversity microbial communities related to Gram-positive Firmicutes and hydrogen-oxidizing bacteria. Interestingly, unlike Lost City, there has been little evidence for significant archaeal populations in the continental subsurface to date. Culturing studies at the sites yielded numerous alkaliphilic isolates on nutrient-rich agar and putative iron-reducing bacteria in anaerobic incubations, many of which are related to known alkaliphilic and subsurface isolates. Finally, metagenomic data reinforce the culturing results, indicating the presence of genes associated with organotrophy, hydrogen oxidation, and iron reduction in seep fluid samples. Our data provide insight into the lifestyles of serpentinite subsurface microbial populations and targets for future quantitative exploration using both biochemical and geochemical approaches.

  14. Subsurface connection methods for subsurface heaters

    SciTech Connect

    Vinegar, Harold J.; Bass, Ronald Marshall; Kim, Dong Sub; Mason, Stanley Leroy; Stegemeier, George Leo; Keltner, Thomas Joseph; Carl, Jr., Frederick Gordon

    2010-12-28

    A system for heating a subsurface formation is described. The system includes a first elongated heater in a first opening in the formation. The first elongated heater includes an exposed metal section in a portion of the first opening. The portion is below a layer of the formation to be heated. The exposed metal section is exposed to the formation. A second elongated heater is in a second opening in the formation. The second opening connects to the first opening at or near the portion of the first opening below the layer to be heated. At least a portion of an exposed metal section of the second elongated heater is electrically coupled to at least a portion of the exposed metal section of the first elongated heater in the portion of the first opening below the layer to be heated.

  15. SUBSURFACE EMPLACEMENT TRANSPORTATION SYSTEM

    SciTech Connect

    T. Wilson; R. Novotny

    1999-11-22

    The objective of this analysis is to identify issues and criteria that apply to the design of the Subsurface Emplacement Transportation System (SET). The SET consists of the track used by the waste package handling equipment, the conductors and related equipment used to supply electrical power to that equipment, and the instrumentation and controls used to monitor and operate those track and power supply systems. Major considerations of this analysis include: (1) Operational life of the SET; (2) Geometric constraints on the track layout; (3) Operating loads on the track; (4) Environmentally induced loads on the track; (5) Power supply (electrification) requirements; and (6) Instrumentation and control requirements. This analysis will provide the basis for development of the system description document (SDD) for the SET. This analysis also defines the interfaces that need to be considered in the design of the SET. These interfaces include, but are not limited to, the following: (1) Waste handling building; (2) Monitored Geologic Repository (MGR) surface site layout; (3) Waste Emplacement System (WES); (4) Waste Retrieval System (WRS); (5) Ground Control System (GCS); (6) Ex-Container System (XCS); (7) Subsurface Electrical Distribution System (SED); (8) MGR Operations Monitoring and Control System (OMC); (9) Subsurface Facility System (SFS); (10) Subsurface Fire Protection System (SFR); (11) Performance Confirmation Emplacement Drift Monitoring System (PCM); and (12) Backfill Emplacement System (BES).

  16. Mars penetrator: Subsurface science mission

    NASA Technical Reports Server (NTRS)

    Lumpkin, C. K.

    1974-01-01

    A penetrator system to emplace subsurface science on the planet Mars is described. The need for subsurface science is discussed, and the technologies for achieving successful atmospheric entry, Mars penetration, and data retrieval are presented.

  17. Design of 300A constant current electronic load

    NASA Astrophysics Data System (ADS)

    Cai, Ying

    2016-01-01

    Energy efficient and stable power supply is the core of most electronic products. DC electronic load is essential equipment to calibrate the DC regulated power supply. with the development of power industry towards to diversification and complication, the electronic load equipment for testing power supply is put forward higher requirements. Quality of electronic load equipment is mainly reflected in three aspects, measurement accuracy, completeness of measuring project and richness of load characteristic. In the paper, the high power and constant current DC electronic load is designed. Two pieces of D/A converter are used to constitute the 20 D/A conversion unit, to realize the minimum resolution of 0.045 mV. Four magnetic rings of high permeability and magnetic properties consistency, and the corresponding processing unit circuit compose the current sampling unit, which solve a key problem and difficulty of high precision and large current test. The three groups of 600 W power modules in parallel to realize the function of 1800 W power constant current. The electronic load has the 0 ~ 300A constant current characteristic, uncertainty of measurement is 1×10-4, and the maximum load voltage is 5V. After testing, every specifications have reached the design requirements. The load is mainly used for the metrology of DC regulated power supply.

  18. Subsurface contaminants focus area

    SciTech Connect

    1996-08-01

    The US Department of Enregy (DOE) Subsurface Contaminants Focus Area is developing technologies to address environmental problems associated with hazardous and radioactive contaminants in soil and groundwater that exist throughout the DOE complex, including radionuclides, heavy metals; and dense non-aqueous phase liquids (DNAPLs). More than 5,700 known DOE groundwater plumes have contaminated over 600 billion gallons of water and 200 million cubic meters of soil. Migration of these plumes threatens local and regional water sources, and in some cases has already adversely impacted off-site rsources. In addition, the Subsurface Contaminants Focus Area is responsible for supplying technologies for the remediation of numerous landfills at DOE facilities. These landfills are estimated to contain over 3 million cubic meters of radioactive and hazardous buried Technology developed within this specialty area will provide efective methods to contain contaminant plumes and new or alternative technologies for development of in situ technologies to minimize waste disposal costs and potential worker exposure by treating plumes in place. While addressing contaminant plumes emanating from DOE landfills, the Subsurface Contaminants Focus Area is also working to develop new or alternative technologies for the in situ stabilization, and nonintrusive characterization of these disposal sites.

  19. Connecting Surface Planting with Subsurface Erosion Due to Groundwater Flow

    NASA Astrophysics Data System (ADS)

    Reardon, M.; Curran, J. C.

    2014-12-01

    Bank erosion and failure is a major contributor of fine sediment to streams and rivers, and can be driven by subsurface flow. In restoration projects, vegetation is often planted on banks to reduce erosion and stabilize the banks. However, the relationship between subsurface flow, erosion and vegetation remains somewhat speculative. A comparative study quantified the effect of surface planting on subsurface erosion and soil strength. Six 32-gallon containers were layered with a sandy loam overlying a highly conductive sand layer and a confining clay. Three treatments were applied in pairs: switchgrass (Panicum virgatum L.), sod (turf-type tall fescue and Kentucky bluegrass mix), and no vegetation. After a vegetation establishment period, the 2, 10, and 100 year rainfalls were simulated. Samples collected from ports in the containers were analyzed for subsurface drainage volume and suspended sediment concentration. After all rainfall simulations, a sediment core was taken from each container to measure shear strength and root density. Results indicate the relative benefits of vegetative planting to reduce subsurface erosion during storms and enhance soil strength. Switchgrass reduced the total amount of sediment removed from containers during all three storms when compared to the sod and during the 10 and 100 year storms when compared to the bare ground. Results from the volume analysis were more variable. Switchgrass retained the greatest volume of water from the 100 year storm event, but also released the largest fraction of water in the 2 and 10 year storms. Both sod and switchgrass planting considerably increased the time required for the soil samples to fail despite reducing the shear stress at failure. Where switchgrass grew long, woody roots, the sod developed a dense mat of interconnected thin roots. We suspect the different root patterns between sod and switchgrass to be a dominant factor in the response of the different containers.

  20. Subsurface Flow in Gravel River Bars

    NASA Astrophysics Data System (ADS)

    Bray, E. N.; Dunne, T.

    2014-12-01

    The geomorphic and hydraulic characteristics of gravel bars control the direction, magnitude and spatial patterns of infiltration and exfiltration between rivers and their immediate subsurface environments. Bed undulation, water-surface gradient, alluvial depth, and the spatial variation of hydraulic conductivity (both deterministic trends and stochastic variability) affect the hydrologically-driven groundwater-surface water exchange. In this paper, we use a set of field measurements of morphological and hydrological characteristics along two reaches of the San Joaquin River, California to motivate a systematic analysis of the factors that affect paths and residence times of flow through gravel bars under an observed range of streamflow values. In the field investigation, it is shown that asymmetry of bar morphology is a first-order control on the extent and magnitude of infiltration, which is often represented to produce approximately equal areas of infiltration and seepage under the assumption of sinusoidal bedforms. Infiltration over the length of a bar is shown to be greater at low flow than at high flow because of the effect of water-surface gradient. Hydraulic conductivity (ksat) varies by orders of magnitude and systematic downstream coarsening arises related to the process of bar evolution. The lowest values of ksat were observed where the difference between the topographic gradient and the water-surface gradient is at a maximum and thus where the infiltration would be greatest into a uniform bar of homogeneous gravel. Morphology and fine sediment accumulation in recharge zones exert an important control over the mechanisms driving subsurface fluid exchange. Simulations from a numerical groundwater flow model that isolate the signatures of morphology and streambed sediment patterns on subsurface flow corroborate our interpretation that the infiltration patterns and rates are primarily controlled by bed morphology, with ksat playing a secondary role.

  1. Metalliferous Biosignatures for Deep Subsurface Microbial Activity

    NASA Astrophysics Data System (ADS)

    Parnell, John; Brolly, Connor; Spinks, Sam; Bowden, Stephen

    2016-03-01

    The interaction of microbes and metals is widely assumed to have occurred in surface or very shallow subsurface environments. However new evidence suggests that much microbial activity occurs in the deep subsurface. Fluvial, lacustrine and aeolian `red beds' contain widespread centimetre-scale reduction spheroids in which a pale reduced spheroid in otherwise red rocks contains a metalliferous core. Most of the reduction of Fe (III) in sediments is caused by Fe (III) reducing bacteria. They have the potential to reduce a range of metals and metalloids, including V, Cu, Mo, U and Se, by substituting them for Fe (III) as electron acceptors, which are all elements common in reduction spheroids. The spheroidal morphology indicates that they were formed at depth, after compaction, which is consistent with a microbial formation. Given that the consequences of Fe (III) reduction have a visual expression, they are potential biosignatures during exploration of the terrestrial and extraterrestrial geological record. There is debate about the energy available from Fe (III) reduction on Mars, but the abundance of iron in Martian soils makes it one of the most valuable prospects for life there. Entrapment of the microbes themselves as fossils is possible, but a more realistic target during the exploration of Mars would be the colour contrasts reflecting selective reduction or oxidation. This can be achieved by analysing quartz grains across a reduction spheroid using Raman spectroscopy, which demonstrates its suitability for life detection in subsurface environments. Microbial action is the most suitable explanation for the formation of reduction spheroids and may act as metalliferous biosignatures for deep subsurface microbial activity.

  2. Metalliferous Biosignatures for Deep Subsurface Microbial Activity.

    PubMed

    Parnell, John; Brolly, Connor; Spinks, Sam; Bowden, Stephen

    2016-03-01

    The interaction of microbes and metals is widely assumed to have occurred in surface or very shallow subsurface environments. However new evidence suggests that much microbial activity occurs in the deep subsurface. Fluvial, lacustrine and aeolian 'red beds' contain widespread centimetre-scale reduction spheroids in which a pale reduced spheroid in otherwise red rocks contains a metalliferous core. Most of the reduction of Fe (III) in sediments is caused by Fe (III) reducing bacteria. They have the potential to reduce a range of metals and metalloids, including V, Cu, Mo, U and Se, by substituting them for Fe (III) as electron acceptors, which are all elements common in reduction spheroids. The spheroidal morphology indicates that they were formed at depth, after compaction, which is consistent with a microbial formation. Given that the consequences of Fe (III) reduction have a visual expression, they are potential biosignatures during exploration of the terrestrial and extraterrestrial geological record. There is debate about the energy available from Fe (III) reduction on Mars, but the abundance of iron in Martian soils makes it one of the most valuable prospects for life there. Entrapment of the microbes themselves as fossils is possible, but a more realistic target during the exploration of Mars would be the colour contrasts reflecting selective reduction or oxidation. This can be achieved by analysing quartz grains across a reduction spheroid using Raman spectroscopy, which demonstrates its suitability for life detection in subsurface environments. Microbial action is the most suitable explanation for the formation of reduction spheroids and may act as metalliferous biosignatures for deep subsurface microbial activity.

  3. Metalliferous Biosignatures for Deep Subsurface Microbial Activity.

    PubMed

    Parnell, John; Brolly, Connor; Spinks, Sam; Bowden, Stephen

    2016-03-01

    The interaction of microbes and metals is widely assumed to have occurred in surface or very shallow subsurface environments. However new evidence suggests that much microbial activity occurs in the deep subsurface. Fluvial, lacustrine and aeolian 'red beds' contain widespread centimetre-scale reduction spheroids in which a pale reduced spheroid in otherwise red rocks contains a metalliferous core. Most of the reduction of Fe (III) in sediments is caused by Fe (III) reducing bacteria. They have the potential to reduce a range of metals and metalloids, including V, Cu, Mo, U and Se, by substituting them for Fe (III) as electron acceptors, which are all elements common in reduction spheroids. The spheroidal morphology indicates that they were formed at depth, after compaction, which is consistent with a microbial formation. Given that the consequences of Fe (III) reduction have a visual expression, they are potential biosignatures during exploration of the terrestrial and extraterrestrial geological record. There is debate about the energy available from Fe (III) reduction on Mars, but the abundance of iron in Martian soils makes it one of the most valuable prospects for life there. Entrapment of the microbes themselves as fossils is possible, but a more realistic target during the exploration of Mars would be the colour contrasts reflecting selective reduction or oxidation. This can be achieved by analysing quartz grains across a reduction spheroid using Raman spectroscopy, which demonstrates its suitability for life detection in subsurface environments. Microbial action is the most suitable explanation for the formation of reduction spheroids and may act as metalliferous biosignatures for deep subsurface microbial activity. PMID:26376912

  4. Comparison and assessment of four sediment particle-size analysis methodologies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sediment particle-size analysis is a fundamental component of a wide variety of environmental disciplines such as sediment transport dynamics, subsurface and groundwater flow, lacustrine depositional history, and nutrient transport. There are several readily available methods for measuring particle ...

  5. Subsurface fracture spacing

    SciTech Connect

    Lorenz, J.C. ); Hill, R.E. )

    1991-01-01

    This study was undertaken in order to document and analyze the unique set of data on subsurface fracture characteristics, especially spacing, provided by the US Department of Energy's Slant Hole Completion Test well (SHCT-1) in the Piceance Basin, Colorado. Two hundred thirty-six (236) ft (71.9 m) of slant core and 115 ft (35.1 m) of horizontal core show irregular, but remarkably close, spacings for 72 natural fractures cored in sandstone reservoirs of the Mesaverde Group. Over 4200 ft (1280 m) of vertical core (containing 275 fractures) from the vertical Multiwell Experiment wells at the same location provide valuable information on fracture orientation, termination, and height, but only data from the SHCT-1 core allow calculations of relative fracture spacing. Within the 162-ft (49-m) thick zone of overlapping core from the vertical and deviated wellbores, only one fracture is present in vertical core whereas 52 fractures occur in the equivalent SHCT-1 core. The irregular distribution of regional-type fractures in these heterogeneous reservoirs suggests that measurements of average fracture spacing'' are of questionable value as direct input parameters into reservoir engineering models. Rather, deviated core provides data on the relative degree of fracturing, and confirms that cross fractures can be rare in the subsurface. 13 refs., 11 figs.

  6. Subsurface Tectonics and Pingos of Northern Alaska

    NASA Astrophysics Data System (ADS)

    Skirvin, S.; Casavant, R.; Burr, D.

    2008-12-01

    We describe preliminary results of a two-phase study that investigated links between subsurface structural and stratigraphic controls, and distribution of hydrostatic pingos on the central coastal plain of Arctic Alaska. Our 2300 km2 study area is underlain by a complete petroleum system that supports gas, oil and water production from 3 of the largest oil fields in North America. In addition, gas hydrate deposits exist in this area within and just below the permafrost interval at depths of 600 to 1800 feet below sea level. Phase 1 of the study compared locations of subsurface faults and pingos for evidence of linkages between faulting and pingo genesis and distribution. Several hundred discrete fault features were digitized from published data and georeferenced in a GIS database. Fault types were determined by geometry and sense of slip derived from well log and seismic maps. More than 200 pingos and surface sediment type associated with their locations were digitized from regional surficial geology maps within an area that included wire line and seismic data coverage. Beneath the pingos lies an assemblage of high-angle normal and transtensional faults that trend NNE and NW; subsidiary trends are EW and NNW. Quaternary fault reactivation is evidenced by faults that displaced strata at depths exceeding 3000 meters below sea level and intersect near-surface units. Unpublished seismic images and cross-section analysis support this interpretation. Kinematics and distribution of reactivated faults are linked to polyphase deformational history of the region that includes Mesozoic rift events, succeeded by crustal shortening and uplift of the Brooks Range to the south, and differential subsidence and segmentation of a related foreland basin margin beneath the study area. Upward fluid migration, a normal process in basin formation and fault reactivation, may play yet unrecognized roles in the genesis (e.g. fluid charging) of pingos and groundwater hydrology. Preliminary

  7. Imaging subsurface geology and volatile organic compound plumes

    SciTech Connect

    Qualheim, B.J.; Daley, P.F.; Johnson, V.; McPherrin, R.V.; Laguna, G.

    1992-03-01

    Lawrence Livermore National Laboratory (LLNL) (Fig. 1) is in the final stages of the Superfund decisionmaking process for site remediation and restoration. In the process of characterizing the subsurface of the LLNL site, we have developed unique methods of collecting, storing, retrieving, and imaging geologic and chemical data from more than 350 drill holes. The lateral and vertical continuity of subsurface paleostream channels were mapped for the entire LLNL site using geologic descriptions from core samples, cuttings, and interpretations from geophysical logs. A computer-aided design and drafting program, SLICE, written at LLNL, was used to create two-dimensional maps of subsurface sediments, and state-of-the-art software produced three-dimensional images of the volatile organic compound (VOC) plumes using data from water and core fluid analyses.

  8. Heating Unsaturated Sediments Using Solar Energy to Enhance Passive Sediment Remediation Technologies

    NASA Astrophysics Data System (ADS)

    Rossman, A.

    2002-12-01

    Sediment heating has been shown to enhance passive sediment remediation technologies such as bioremediation and barometric pumping (passive soil venting). Sediment heating raises the slow remediation rates that often limit the widespread use of these technologies. In bioremediation applications, a 10 degree C increase in subsurface temperature is expected to double the microbial activity, and thus the remediation rate. The removal rate of tetracholorethylene (PCE - a common subsurface contaminant) by passive soil vapor extraction is expected to nearly double in low-permeable sediments when the subsurface is heated 10 degree C from ambient temperatures due to an increased vapor pressure in the PCE. When the sediment is heated using renewable energy sources, these thermally enhanced remediation technologies can be environmentally benign alternatives to conventional remediation techniques that rely on large external energy inputs. The thermally enhanced passive technologies may be particularly useful for remediating unsaturated, low-permeable lenses that are troublesome to most conventional remediation technologies such as conventional soil vapor extraction and co-solvent flushes. The main objective of this work was to quantify subsurface sediment heating using a solar powered heat injection well. To do this, a pilot sediment heating system was installed in Vermont and high resolution meteorological and sediment temperature data were collected using a stand-alone data acquisition system. Unsaturated, silty sediments were heated in-situ by converting the direct and indirect solar energy available at the surface to heat energy in the subsurface using stand-alone renewable energy sources and a resistive element heat injection well. The heat injection well was powered by a 600-W passively tracking photovoltaic (PV) array and a small 1.2-m swept area wind turbine. It is envisioned that the heat injection well would be placed directly into an area of high subsurface

  9. Containment of subsurface contaminants

    DOEpatents

    Corey, J.C.

    1994-09-06

    A barrier is disclosed for reducing the spread of a plume of subsurface contaminants. The apparatus includes a well system for injecting a fluid, such as air, just outside and below the periphery of the plume. The fluid is injected at a pressure sufficient to lower the hydraulic conductivity of the soil from the point of injection to the surface thus establishing a curtain-like barrier to groundwater movement. The barrier is established upgradient of the plume to divert groundwater away, or preferably completely around the plume to reduce the flow of groundwater into or out of the plume. The barrier enables the remediation of the confined contamination and then, when the injection of the fluid is halted, the barrier quickly dissipates. 5 figs.

  10. Nonintrusive subsurface surveying capability

    SciTech Connect

    Tunnell, T.W.; Cave, S.P.

    1994-06-01

    This presentation describes the capabilities of a ground-pentrating radar (GPR) system developed by EG&G Energy Measurements (EM), a prime contractor to the Department of Energy (DOE). The focus of the presentation will be on the subsurface survey of DOE site TA-21 in Los Alamos, New Mexico. EG&G EM developed the system for the Department of Defense. The system is owned by the Department of the Army and currently resides at KO in Albuquerque. EM is pursuing efforts to transfer this technology to environmental applications such as waste-site characterization with DOE encouragement. The Army has already granted permission to use the system for the waste-site characterization activities.

  11. Containment of subsurface contaminants

    DOEpatents

    Corey, John C.

    1994-01-01

    A barrier for reducing the spread of a plume of subsurface contaminants. The apparatus includes a well system for injecting a fluid, such as air, just outside and below the periphery of the plume. The fluid is injected at a pressure sufficient to lower the hydraulic conductivity of the soil from the point of injection to the surface thus establishing a curtain-like barrier to groundwater movement. The barrier is established upgradient of the plume to divert groundwater away, or preferably completely around the plume to reduce the flow of groundwater into or out of the plume. The barrier enables the remediation of the confined contamination and then, when the injection of the fluid is halted, the barrier quickly dissipates.

  12. Uranium Biomineralization by Natural Microbial Phosphatase Activities in the Subsurface

    SciTech Connect

    Sobecky, Patricia A.

    2015-04-06

    In this project, inter-disciplinary research activities were conducted in collaboration among investigators at The University of Alabama (UA), Georgia Institute of Technology (GT), Lawrence Berkeley National Laboratory (LBNL), Brookhaven National Laboratory (BNL), the DOE Joint Genome Institute (JGI), and the Stanford Synchrotron Radiation Light source (SSRL) to: (i) confirm that phosphatase activities of subsurface bacteria in Area 2 and 3 from the Oak Ridge Field Research Center result in solid U-phosphate precipitation in aerobic and anaerobic conditions; (ii) investigate the eventual competition between uranium biomineralization via U-phosphate precipitation and uranium bioreduction; (iii) determine subsurface microbial community structure changes of Area 2 soils following organophosphate amendments; (iv) obtain the complete genome sequences of the Rahnella sp. Y9-602 and the type-strain Rahnella aquatilis ATCC 33071 isolated from these soils; (v) determine if polyphosphate accumulation and phytate hydrolysis can be used to promote U(VI) biomineralization in subsurface sediments; (vi) characterize the effect of uranium on phytate hydrolysis by a new microorganism isolated from uranium-contaminated sediments; (vii) utilize positron-emission tomography to label and track metabolically-active bacteria in soil columns, and (viii) study the stability of the uranium phosphate mineral product. Microarray analyses and mineral precipitation characterizations were conducted in collaboration with DOE SBR-funded investigators at LBNL. Thus, microbial phosphorus metabolism has been shown to have a contributing role to uranium immobilization in the subsurface.

  13. Microbial communities in the deep subsurface

    NASA Astrophysics Data System (ADS)

    Krumholz, Lee R.

    The diversity of microbial populations and microbial communities within the earth's subsurface is summarized in this review. Scientists are currently exploring the subsurface and addressing questions of microbial diversity, the interactions among microorganisms, and mechanisms for maintenance of subsurface microbial communities. Heterotrophic anaerobic microbial communities exist in relatively permeable sandstone or sandy sediments, located adjacent to organic-rich deposits. These microorganisms appear to be maintained by the consumption of organic compounds derived from adjacent deposits. Sources of organic material serving as electron donors include lignite-rich Eocene sediments beneath the Texas coastal plain, organic-rich Cretaceous shales from the southwestern US, as well as Cretaceous clays containing organic materials and fermentative bacteria from the Atlantic Coastal Plain. Additionally, highly diverse microbial communities occur in regions where a source of organic matter is not apparent but where igneous rock is present. Examples include the basalt-rich subsurface of the Columbia River valley and the granitic subsurface regions of Sweden and Canada. These subsurface microbial communities appear to be maintained by the action of lithotrophic bacteria growing on H2 that is chemically generated within the subsurface. Other deep-dwelling microbial communities exist within the deep sediments of oceans. These systems often rely on anaerobic metabolism and sulfate reduction. Microbial colonization extends to the depths below which high temperatures limit the ability of microbes to survive. Energy sources for the organisms living in the oceanic subsurface may originate as oceanic sedimentary deposits. In this review, each of these microbial communities is discussed in detail with specific reference to their energy sources, their observed growth patterns, and their diverse composition. This information is critical to develop further understanding of subsurface

  14. Subsurface Ventilation System Description Document

    SciTech Connect

    2000-10-12

    The Subsurface Ventilation System supports the construction and operation of the subsurface repository by providing air for personnel and equipment and temperature control for the underground areas. Although the system is located underground, some equipment and features may be housed or located above ground. The system ventilates the underground by providing ambient air from the surface throughout the subsurface development and emplacement areas. The system provides fresh air for a safe work environment and supports potential retrieval operations by ventilating and cooling emplacement drifts. The system maintains compliance within the limits established for approved air quality standards. The system maintains separate ventilation between the development and waste emplacement areas. The system shall remove a portion of the heat generated by the waste packages during preclosure to support thermal goals. The system provides temperature control by reducing drift temperature to support potential retrieval operations. The ventilation system has the capability to ventilate selected drifts during emplacement and retrieval operations. The Subsurface Facility System is the main interface with the Subsurface Ventilation System. The location of the ducting, seals, filters, fans, emplacement doors, regulators, and electronic controls are within the envelope created by the Ground Control System in the Subsurface Facility System. The Subsurface Ventilation System also interfaces with the Subsurface Electrical System for power, the Monitored Geologic Repository Operations Monitoring and Control System to ensure proper and safe operation, the Safeguards and Security System for access to the emplacement drifts, the Subsurface Fire Protection System for fire safety, the Emplacement Drift System for repository performance, and the Backfill Emplacement and Subsurface Excavation Systems to support ventilation needs.

  15. Subsurface Ventilation System Description Document

    SciTech Connect

    Eric Loros

    2001-07-25

    The Subsurface Ventilation System supports the construction and operation of the subsurface repository by providing air for personnel and equipment and temperature control for the underground areas. Although the system is located underground, some equipment and features may be housed or located above ground. The system ventilates the underground by providing ambient air from the surface throughout the subsurface development and emplacement areas. The system provides fresh air for a safe work environment and supports potential retrieval operations by ventilating and cooling emplacement drifts. The system maintains compliance within the limits established for approved air quality standards. The system maintains separate ventilation between the development and waste emplacement areas. The system shall remove a portion of the heat generated by the waste packages during preclosure to support thermal goals. The system provides temperature control by reducing drift temperature to support potential retrieval operations. The ventilation system has the capability to ventilate selected drifts during emplacement and retrieval operations. The Subsurface Facility System is the main interface with the Subsurface Ventilation System. The location of the ducting, seals, filters, fans, emplacement doors, regulators, and electronic controls are within the envelope created by the Ground Control System in the Subsurface Facility System. The Subsurface Ventilation System also interfaces with the Subsurface Electrical System for power, the Monitored Geologic Repository Operations Monitoring and Control System to ensure proper and safe operation, the Safeguards and Security System for access to the emplacement drifts, the Subsurface Fire Protection System for fire safety, the Emplacement Drift System for repository performance, and the Backfill Emplacement and Subsurface Excavation Systems to support ventilation needs.

  16. Ecology, physiology, and phylogeny of deep subsurface Sphingomonas sp.

    SciTech Connect

    Fredrickson, Jim K.; Balkwill, David L.; Romine, Margaret F.; Shi, T

    1999-10-01

    Several new species of the genus Sphingomonas including S. aromaticivorans, S. stygia, and S. subterranea that have the capacity for degrading a broad range of aromatic compounds including toluene, naphthalene, xylenes, p-cresol, fluorene, biphenyl, and dibenzothiophene, were isolated from deeply-buried (>200 m) sediments of the US Atlantic coastal plain (ACP). In S. aromaticivorans F199, many of the genes involved in the catabolism of these aromatic compounds are encoded on a 184-kb conjugative plasmid; some of the genes involved in aromatic catabolism are plasmid-encoded in the other strains as well. Members of the genus Sphingomonas were common among aerobic heterotrophic bacteria cultured from ACP sediments and have been detected in deep subsurface environments elsewhere. The major source of organic carbon for heterotrophic metabolism in ACP deep aquifers is lignite that originated from plant material buried with the sediments. We speculate that the ability of the subsurface Sphingomonas strains to degrade a wide array of aromatic compounds represents an adaptation for utilization of sedimentary lignite. These and related subsurface Sphingomonas spp may play an important role in the transformation of sedimentary organic carbon in the aerobic and microaerobic regions of the deep aquifers of the ACP.

  17. From surface to subsurface and back again: the contribution of subsurface particle motion to surface armoring

    NASA Astrophysics Data System (ADS)

    Ferdowsi, B.; Jerolmack, D. J.; Ortiz, C. P.; Houssais, M.

    2015-12-01

    Armoring is the development of a coarse surface layer of sediments on a river bed, which overlies a smaller and typically more heterogeneous substrate. All existing models for this phenomenon are predicated on the idea that armoring develops due to size-selective transport and kinetic sieving at the surface of the granular bed. Here examine the development of armoring in the absence of size-selective surface transport, and demonstrate that subsurface particle movement can create an armored surface layer. We first conduct experiments in a laminar and annular flume, over a range of Shields stresses, with bimodal and refractive index-matched spherical sediments; this allows us to image the internal motion of the granular bed that is sheared from above by a viscous oil. Fluid-driven particle motion of the surface layer results in granular shear, that drives motion deep into the bed. This subsurface motion causes an upward migration of coarser particles, at a rate that is proportional to the granular shear rate. Comparison of experimental results to an existing continuum-granular flow model suggest that armoring in our bed-load exeriments is entirely consistent with shear-induced segregation in dry avalanches - but is slower. There is no size-selective transport at the surface in the experiments, as the annular flume is mass conserving and all particles move as bed load; this was confirmed by observation. To probe the granular physics of armor development further, we perform numerical simulations using a discrete element model (DEM) of granular flow, with and without damping. Simulations reproduce salient features of the experiments, and indicate that armoring is robust but that the rate of segregation is related to the degree of viscous damping. We posit that subsurface granular flow is an important and perhaps dominant contributor to surface armoring in rivers. More generally, this work shows how information is transferred from the surface to the subsurface and back

  18. Subsurface Facility System Description Document

    SciTech Connect

    Eric Loros

    2001-07-31

    The Subsurface Facility System encompasses the location, arrangement, size, and spacing of the underground openings. This subsurface system includes accesses, alcoves, and drifts. This system provides access to the underground, provides for the emplacement of waste packages, provides openings to allow safe and secure work conditions, and interfaces with the natural barrier. This system includes what is now the Exploratory Studies Facility. The Subsurface Facility System physical location and general arrangement help support the long-term waste isolation objectives of the repository. The Subsurface Facility System locates the repository openings away from main traces of major faults, away from exposure to erosion, above the probable maximum flood elevation, and above the water table. The general arrangement, size, and spacing of the emplacement drifts support disposal of the entire inventory of waste packages based on the emplacement strategy. The Subsurface Facility System provides access ramps to safely facilitate development and emplacement operations. The Subsurface Facility System supports the development and emplacement operations by providing subsurface space for such systems as ventilation, utilities, safety, monitoring, and transportation.

  19. Microbial Transport in the Subsurface

    SciTech Connect

    Ginn, Timothy R.; Camesano, Terri; Scheibe, Timothy D.; Nelson, Kirk B.; Clement, T. P.; Wood, Brian D.

    2005-12-01

    In this article we focus on the physical, chemical, and biological processes involved in the transport of bacteria in the saturated subsurface. We will first review conceptual models of bacterial phases in the subsurface, and then the processes controlling fate and transport on short (e.g., bioremediation) time scales. Finally we briefly review field bacterial transport experiments and discuss a number of issues that impact the application of current process descriptions and models at the field scale.

  20. Characterization of the methanotrophic bacterial community present in a trichloroethylene-contaminated subsurface groundwater site

    SciTech Connect

    Bowman, J.P.; Jimenez, L.; Rosario, I.; Sayler, G.S. ); Hazen, T.C. )

    1993-08-01

    Contamination of subsurface environments with chlorinated hydrocarbons is a potentially serious threat to drinking water sources. Subsurface microbial communities degrade a wide variety of chlorinated hydrocarbons in the laboratory. This paper examines the ground water methanotrophic community, finding that it is dominated by sMMO-producting group II methanotrophs, suggested by the presence of sMMO genes in the aquifer sediments, and well adapted to oligotrophic conditions. sMMO is expressed in the sediments, but it is not clear that this is sufficient for in situ bioremediation. 46 refs., 2 figs., 2 tabs.

  1. Subsurface Geotechnical Parameters Report

    SciTech Connect

    D. Rigby; M. Mrugala; G. Shideler; T. Davidsavor; J. Leem; D. Buesch; Y. Sun; D. Potyondy; M. Christianson

    2003-12-17

    The Yucca Mountain Project is entering a the license application (LA) stage in its mission to develop the nation's first underground nuclear waste repository. After a number of years of gathering data related to site characterization, including activities ranging from laboratory and site investigations, to numerical modeling of processes associated with conditions to be encountered in the future repository, the Project is realigning its activities towards the License Application preparation. At the current stage, the major efforts are directed at translating the results of scientific investigations into sets of data needed to support the design, and to fulfill the licensing requirements and the repository design activities. This document addresses the program need to address specific technical questions so that an assessment can be made about the suitability and adequacy of data to license and construct a repository at the Yucca Mountain Site. In July 2002, the U.S. Nuclear Regulatory Commission (NRC) published an Integrated Issue Resolution Status Report (NRC 2002). Included in this report were the Repository Design and Thermal-Mechanical Effects (RDTME) Key Technical Issues (KTI). Geotechnical agreements were formulated to resolve a number of KTI subissues, in particular, RDTME KTIs 3.04, 3.05, 3.07, and 3.19 relate to the physical, thermal and mechanical properties of the host rock (NRC 2002, pp. 2.1.1-28, 2.1.7-10 to 2.1.7-21, A-17, A-18, and A-20). The purpose of the Subsurface Geotechnical Parameters Report is to present an accounting of current geotechnical information that will help resolve KTI subissues and some other project needs. The report analyzes and summarizes available qualified geotechnical data. It evaluates the sufficiency and quality of existing data to support engineering design and performance assessment. In addition, the corroborative data obtained from tests performed by a number of research organizations is presented to reinforce

  2. Actinobacterial diversity across a marine transgression in the deep subsurface off Shimokita Peninsula, Japan

    NASA Astrophysics Data System (ADS)

    Harrison, B. K.; Bailey, J. V.

    2013-12-01

    Sediment horizons represent a significant - but not permanent - barrier to microbial transport. Cells commonly attach to mineral surfaces in unconsolidated sediments. However, by taxis, growth, or passive migration under advecting fluids, some portion of the microbial community may transgress sedimentary boundaries. Few studies have attempted to constrain such transport of community signatures in the marine subsurface and its potential impact on biogeography. Integrated Ocean Drilling Program (IODP) Expedition 337 off the Shimokita Peninsula recovered sediments over a greater than 1km interval representing a gradual decrease of terrestrial influence, from tidal to continental shelf depositional settings. This sequence represents a key opportunity to link subsurface microbial communities to lithological variability and investigate the permanence of community signatures characteristic of distinct depositional regimes. The phylogenetic connectivity between marine and terrestrially-influenced deposits may demonstrate to what degree sediments offer a substantial barrier to cell transport in the subsurface. Previous work has demonstrated that the Actinobacterial phylum is broadly distributed in marine sediments (Maldonado et al., 2005), present and active in the deep subsurface (Orsi et al., 2013), and that marine and terrestrial lineages may potentially be distinguished by 16S rRNA gene sequencing (e.g. Prieto-Davó et al., 2013). We report on Actinobacteria-specific 16S rRNA gene diversity recovered between 1370 and 2642 mbsf with high-throughput sequencing using the Illumina MiSeq platform, as well as selective assembly and analysis of environmental clone libraries.

  3. Geophysical monitoring of microbial activity during stimulated subsurface bioremediation

    NASA Astrophysics Data System (ADS)

    Williams, K. H.; Kemna, A.; Wilkins, M.; Druhan, J.; Arntzen, E.; N'guessan, L.; Long, P.; Hubbard, S.; Banfield, J.

    2007-12-01

    Understanding how microorganisms alter their physical and chemical environment during bioremediation is hindered by our inability to resolve subsurface microbial activity with high spatial resolution. Here we demonstrate the use of a minimally invasive geophysical technique to monitor microbe-mediated iron and sulfate reduction during acetate amendment of a uranium-contaminated aquifer near Rifle, CO. During induced polarization (IP) measurements, spatiotemporal variations in the phase response between applied and measured voltages correlated with changes in groundwater geochemistry indicative of microbial iron and sulfate reduction and sulfide mineral precipitation. The enhanced sensitivity of the high and low frequency phase responses to accumulated aqueous iron and sulfide, respectively, provide the ability to discriminate the dominant subsurface biogeochemical process. The spectral effect was verified and calibrated using a biostimulated column experiment containing Rifle sediments and groundwater. Sediments and fluids recovered from regions of the field site exhibiting an anomalous phase response were enriched in sorbed Fe(II) and cell-associated 2-4 nm diameter FeS nanoparticles. These mineral precipitates and accumulated electroactive ions altered the ability of pore fluids to conduct electrical charge, accounting for the IP response. The results reveal the usefulness of multi-frequency IP measurements for discriminating mineralogical and geochemical changes during stimulated subsurface bioremediation.

  4. Pore geometry, avalanching, and subsurface flow: A sand infiltration model

    NASA Astrophysics Data System (ADS)

    Leonardson, R.; Hunt, J. R.; Dietrich, W. E.

    2009-12-01

    The deposition of sand into gravel riverbeds has been well-documented, along with its negative impacts on developing salmon eggs and riverbank extraction for water supplies. Dam releases may be used on regulated rivers to flush the bed of fine sediment, but it is not generally known how deep the sand deposit extends or how much sand is there. One-dimensional (plane-bed) experiments consistently show that the depth of infiltration is a function of the sand and gravel grain size distributions and that the saturation sand fraction is near 8-10%. However, precise empirical relationships developed in individual studies do poorly at predicting the results of other experiments. Furthermore, no infiltration model includes the effect of flow conditions in the water column, although flow conditions clearly impact the deposit characteristics. We propose a mechanistic model for the infiltration of fine sediment and compare its predictions to the results of two recent infiltration experiments. This model is based on geometric arguments about pore and particle shape and five mechanisms: particle settling, particle capture, subsurface avalanching, average subsurface flow, and subsurface pressure fluctuations. The model successfully predicts for both experiments the fraction of sand deposited and the shape of that deposit as a function of depth.

  5. Microbial communities in the deep subsurface

    NASA Astrophysics Data System (ADS)

    Krumholz, Lee R.

    The diversity of microbial populations and microbial communities within the earth's subsurface is summarized in this review. Scientists are currently exploring the subsurface and addressing questions of microbial diversity, the interactions among microorganisms, and mechanisms for maintenance of subsurface microbial communities. Heterotrophic anaerobic microbial communities exist in relatively permeable sandstone or sandy sediments, located adjacent to organic-rich deposits. These microorganisms appear to be maintained by the consumption of organic compounds derived from adjacent deposits. Sources of organic material serving as electron donors include lignite-rich Eocene sediments beneath the Texas coastal plain, organic-rich Cretaceous shales from the southwestern US, as well as Cretaceous clays containing organic materials and fermentative bacteria from the Atlantic Coastal Plain. Additionally, highly diverse microbial communities occur in regions where a source of organic matter is not apparent but where igneous rock is present. Examples include the basalt-rich subsurface of the Columbia River valley and the granitic subsurface regions of Sweden and Canada. These subsurface microbial communities appear to be maintained by the action of lithotrophic bacteria growing on H2 that is chemically generated within the subsurface. Other deep-dwelling microbial communities exist within the deep sediments of oceans. These systems often rely on anaerobic metabolism and sulfate reduction. Microbial colonization extends to the depths below which high temperatures limit the ability of microbes to survive. Energy sources for the organisms living in the oceanic subsurface may originate as oceanic sedimentary deposits. In this review, each of these microbial communities is discussed in detail with specific reference to their energy sources, their observed growth patterns, and their diverse composition. This information is critical to develop further understanding of subsurface

  6. Genomic inference of the metabolism of cosmopolitan subsurface Archaea, Hadesarchaea.

    PubMed

    Baker, Brett J; Saw, Jimmy H; Lind, Anders E; Lazar, Cassandre Sara; Hinrichs, Kai-Uwe; Teske, Andreas P; Ettema, Thijs J G

    2016-02-15

    The subsurface biosphere is largely unexplored and contains a broad diversity of uncultured microbes(1). Despite being one of the few prokaryotic lineages that is cosmopolitan in both the terrestrial and marine subsurface(2-4), the physiological and ecological roles of SAGMEG (South-African Gold Mine Miscellaneous Euryarchaeal Group) Archaea are unknown. Here, we report the metabolic capabilities of this enigmatic group as inferred from genomic reconstructions. Four high-quality (63-90% complete) genomes were obtained from White Oak River estuary and Yellowstone National Park hot spring sediment metagenomes. Phylogenomic analyses place SAGMEG Archaea as a deeply rooting sister clade of the Thermococci, leading us to propose the name Hadesarchaea for this new Archaeal class. With an estimated genome size of around 1.5 Mbp, the genomes of Hadesarchaea are distinctly streamlined, yet metabolically versatile. They share several physiological mechanisms with strict anaerobic Euryarchaeota. Several metabolic characteristics make them successful in the subsurface, including genes involved in CO and H2 oxidation (or H2 production), with potential coupling to nitrite reduction to ammonia (DNRA). This first glimpse into the metabolic capabilities of these cosmopolitan Archaea suggests they are mediating key geochemical processes and are specialized for survival in the subsurface biosphere.

  7. Genomic inference of the metabolism of cosmopolitan subsurface Archaea, Hadesarchaea.

    PubMed

    Baker, Brett J; Saw, Jimmy H; Lind, Anders E; Lazar, Cassandre Sara; Hinrichs, Kai-Uwe; Teske, Andreas P; Ettema, Thijs J G

    2016-01-01

    The subsurface biosphere is largely unexplored and contains a broad diversity of uncultured microbes(1). Despite being one of the few prokaryotic lineages that is cosmopolitan in both the terrestrial and marine subsurface(2-4), the physiological and ecological roles of SAGMEG (South-African Gold Mine Miscellaneous Euryarchaeal Group) Archaea are unknown. Here, we report the metabolic capabilities of this enigmatic group as inferred from genomic reconstructions. Four high-quality (63-90% complete) genomes were obtained from White Oak River estuary and Yellowstone National Park hot spring sediment metagenomes. Phylogenomic analyses place SAGMEG Archaea as a deeply rooting sister clade of the Thermococci, leading us to propose the name Hadesarchaea for this new Archaeal class. With an estimated genome size of around 1.5 Mbp, the genomes of Hadesarchaea are distinctly streamlined, yet metabolically versatile. They share several physiological mechanisms with strict anaerobic Euryarchaeota. Several metabolic characteristics make them successful in the subsurface, including genes involved in CO and H2 oxidation (or H2 production), with potential coupling to nitrite reduction to ammonia (DNRA). This first glimpse into the metabolic capabilities of these cosmopolitan Archaea suggests they are mediating key geochemical processes and are specialized for survival in the subsurface biosphere. PMID:27572167

  8. Subsurface microbial habitats on Mars

    NASA Technical Reports Server (NTRS)

    Boston, P. J.; Mckay, C. P.

    1991-01-01

    We developed scenarios for shallow and deep subsurface cryptic niches for microbial life on Mars. Such habitats could have considerably prolonged the persistence of life on Mars as surface conditions became increasingly inhospitable. The scenarios rely on geothermal hot spots existing below the near or deep subsurface of Mars. Recent advances in the comparatively new field of deep subsurface microbiology have revealed previously unsuspected rich aerobic and anaerobic microbal communities far below the surface of the Earth. Such habitats, protected from the grim surface conditions on Mars, could receive warmth from below and maintain water in its liquid state. In addition, geothermally or volcanically reduced gases percolating from below through a microbiologically active zone could provide the reducing power needed for a closed or semi-closed microbial ecosystem to thrive.

  9. Endoscopic subsurface imaging in tissues

    SciTech Connect

    Demos, S G; Staggs, M; Radousky, H B

    2001-02-12

    The objective of this work is to develop endoscopic subsurface optical imaging technology that will be able to image different tissue components located underneath the surface of the tissue at an imaging depth of up to 1 centimeter. This effort is based on the utilization of existing technology and components developed for medical endoscopes with the incorporation of the appropriate modifications to implement the spectral and polarization difference imaging technique. This subsurface imaging technique employs polarization and spectral light discrimination in combination with image processing to remove a large portion of the image information from the outer layers of the tissue which leads to enhancement of the contrast and image quality of subsurface tissue structures.

  10. Towed Subsurface Optical Communications Buoy

    NASA Technical Reports Server (NTRS)

    Stirbl, Robert C.; Farr, William H.

    2013-01-01

    The innovation allows critical, high-bandwidth submarine communications at speed and depth. This reported innovation is a subsurface optical communications buoy, with active neutral buoyancy and streamlined flow surface veins for depth control. This novel subsurface positioning for the towed communications buoy enables substantial reduction in water-absorption and increased optical transmission by eliminating the intervening water absorption and dispersion, as well as by reducing or eliminating the beam spread and the pulse spreading that is associated with submarine-launched optical beams.

  11. The Phosphatidylserine and Phosphatidylethanolamine Receptor CD300a Binds Dengue Virus and Enhances Infection

    PubMed Central

    Carnec, Xavier; Meertens, Laurent; Dejarnac, Ophélie; Perera-Lecoin, Manuel; Hafirassou, Mohamed Lamine; Kitaura, Jiro; Ramdasi, Rasika; Schwartz, Olivier

    2015-01-01

    ABSTRACT Dengue virus (DENV) is the etiological agent of the major human arboviral disease. We previously demonstrated that the TIM and TAM families of phosphatidylserine (PtdSer) receptors involved in the phagocytosis of apoptotic cells mediate DENV entry into target cells. We show here that human CD300a, a recently identified phospholipid receptor, also binds directly DENV particles and enhances viral entry. CD300a facilitates infection of the four DENV serotypes, as well as of other mosquito-borne viruses such as West Nile virus and Chikungunya virus. CD300a acts as an attachment factor that enhances DENV internalization through clathrin-mediated endocytosis. CD300a recognizes predominantly phosphatidylethanolamine (PtdEth) and to a lesser extent PtdSer associated with viral particles. Mutation of residues in the IgV domain critical for phospholipid binding abrogate CD300a-mediated enhancement of DENV infection. Finally, we show that CD300a is expressed at the surface of primary macrophages and anti-CD300a polyclonal antibodies partially inhibited DENV infection of these cells. Overall, these data indicate that CD300a is a novel DENV binding receptor that recognizes PtdEth and PtdSer present on virions and enhance infection. IMPORTANCE Dengue disease, caused by dengue virus (DENV), has emerged as the most important mosquito-borne viral disease of humans and is a major global health concern. The molecular bases of DENV-host cell interactions during virus entry are poorly understood, hampering the discovery of new targets for antiviral intervention. We recently discovered that the TIM and TAM proteins, two receptor families involved in the phosphatidylserine (PtdSer)-dependent phagocytic removal of apoptotic cells, interact with DENV particles-associated PtdSer through a mechanism that mimics the recognition of apoptotic cells and mediate DENV infection. In this study, we show that CD300a, a novel identified phospholipid receptor, mediates DENV infection. CD300a

  12. Microbial production and oxidation of methane in deep subsurface

    NASA Astrophysics Data System (ADS)

    Kotelnikova, Svetlana

    2002-10-01

    The goal of this review is to summarize present studies on microbial production and oxidation of methane in the deep subterranean environments. Methane is a long-living gas causing the "greenhouse" effect in the planet's atmosphere. Earlier, the deep "organic carbon poor" subsurface was not considered as a source of "biogenic" methane. Evidence of active methanogenesis and presence of viable methanogens including autotrophic organisms were obtained for some subsurface environments including water-flooded oil-fields, deep sandy aquifers, deep sea hydrothermal vents, the deep sediments and granitic groundwater at depths of 10 to 2000 m below sea level. As a rule, the deep subterranean microbial populations dwell at more or less oligotrophic conditions. Molecular hydrogen has been found in a variety of subsurface environments, where its concentrations were significantly higher than in the tested surface aquatic environments. Chemolithoautotrophic microorganisms from deep aquifers that could grow on hydrogen and carbon dioxide can act as primary producers of organic carbon, initiating heterotrophic food chains in the deep subterranean environments independent of photosynthesis. "Biogenic" methane has been found all over the world. On the basis of documented occurrences, gases in reservoirs and older sediments are similar and have the isotopic character of methane derived from CO 2 reduction. Groundwater representing the methanogenic end member are characterized by a relative depletion of dissolved organic carbon (DOC) in combination with an enrichment in 13C in inorganic carbon, which is consistent with the preferential reduction of 12CO 2 by autotrophic methanogens or acetogens. The isotopic composition of methane formed via CO 2 reduction is controlled by the δ13C of the original CO 2 substrate. Literature data shows that CH 4 as heavy as -40‰ or -50‰ can be produced by the microbial reduction of isotopically heavy CO 2. Produced methane may be oxidized

  13. ASSESSMENT OF THE SUBSURFACE FATE OF MONOETHANOLAMINE

    SciTech Connect

    James A. Sorensen; John R. Gallagher; Lori G. Kays

    2000-05-01

    Burial of amine reclaimer unit sludges and system filters has resulted in contamination of soil at the CanOxy Okotoks decommissioned sour gas-processing plant with amines, amine byproducts, and salts. A three-phase research program was devised to investigate the natural attenuation process that controls the subsurface transport and fate of these contaminants and to apply the results toward the development of a strategy for the remediation of this type of contamination in soils. Phase I experimental activities examined interactions between monoethanolamine (MEA) and sediment, the biodegradability of MEA in soils at various concentrations and temperatures, and the biodegradability of MEA sludge contamination in a soil slurry bioreactor. The transport and fate of MEA in the subsurface was found to be highly dependant on the nature of the release, particularly MEA concentration and conditions of the subsurface environment, i.e., pH, temperature, and oxygen availability. Pure compound biodegradation experiments in soil demonstrated rapid biodegradation of MEA under aerobic conditions and moderate temperatures (>6 C). Phase II landfarming activities confirmed that these contaminants are readily biodegradable in soil under ideal laboratory conditions, yet considerable toxicity was observed in the remaining material. Examination of water extracts from the treated soil suggested that the toxicity is water-soluble. Phase II activities led to the conclusion that landfarming is not the most desirable bioremediation technique; however, an engineered biopile with a leachate collection system could remove the remaining toxic fraction from the soil. Phase III was initiated to conduct field-based experimental activities to examine the optimized remediation technology. A pilot-scale engineered biopile was constructed at a decommissioned gas-sweetening facility in Okotoks, Alberta, Canada. On the basis of a review of the analytical and performance data generated from soil and

  14. Tillage impact on herbicide loss by surface runoff and lateral subsurface flow

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is worldwide interest in conservation tillage practices because they can reduce surface runoff, and agrichemical and sediment losses from farm fields. Since these practices typically increase infiltration, their use may increase subsurface transport of water-soluble contaminants. Thus, to asse...

  15. Tillage impact on herbicide loss by surface runoff and lateral subsurface flow

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is worldwide interest in conservation tillage practices because they can reduce surface runoff, agrichemical, and sediment loss from farm fields. Since these practices typically increase infiltration, their use may increase subsurface transport of water-soluble contaminants. Thus, to assess lo...

  16. Targeting sediment management strategies using sediment quantification and fingerprinting methods

    NASA Astrophysics Data System (ADS)

    Sherriff, Sophie; Rowan, John; Fenton, Owen; Jordan, Phil; hUallacháin, Daire Ó.

    2016-04-01

    Cost-effective sediment management is required to reduce excessive delivery of fine sediment due to intensive land uses such as agriculture, resulting in the degradation of aquatic ecosystems. Prioritising measures to mitigate dominant sediment sources is, however, challenging, as sediment loss risk is spatially and temporally variable between and within catchments. Fluctuations in sediment supply from potential sources result from variations in land uses resulting in increased erodibility where ground cover is low (e.g., cultivated, poached and compacted soils), and physical catchment characteristics controlling hydrological connectivity and transport pathways (surface and/or sub-surface). Sediment fingerprinting is an evidence-based management tool to identify sources of in-stream sediments at the catchment scale. Potential sediment sources are related to a river sediment sample, comprising a mixture of source sediments, using natural physico-chemical characteristics (or 'tracers'), and contributions are statistically un-mixed. Suspended sediment data were collected over two years at the outlet of three intensive agricultural catchments (approximately 10 km2) in Ireland. Dominant catchment characteristics were grassland on poorly-drained soils, arable on well-drained soils and arable on moderately-drained soils. High-resolution (10-min) calibrated turbidity-based suspended sediment and discharge data were combined to quantify yield. In-stream sediment samples (for fingerprinting analysis) were collected at six to twelve week intervals, using time-integrated sediment samplers. Potential sources, including stream channel banks, ditches, arable and grassland field topsoils, damaged road verges and tracks were sampled, oven-dried (<40oC) and sieved (125 microns). Soil and sediment samples were analysed for mineral magnetics, geochemistry and radionuclide tracers, particle size distribution and soil organic carbon. Tracer data were corrected to account for particle

  17. Deep Subsurface Life from North Pond: Enrichment, Isolation, Characterization and Genomes of Heterotrophic Bacteria

    PubMed Central

    Russell, Joseph A.; León-Zayas, Rosa; Wrighton, Kelly; Biddle, Jennifer F.

    2016-01-01

    Studies of subsurface microorganisms have yielded few environmentally relevant isolates for laboratory studies. In order to address this lack of cultivated microorganisms, we initiated several enrichments on sediment and underlying basalt samples from North Pond, a sediment basin ringed by basalt outcrops underlying an oligotrophic water-column west of the Mid-Atlantic Ridge at 22°N. In contrast to anoxic enrichments, growth was observed in aerobic, heterotrophic enrichments from sediment of IODP Hole U1382B at 4 and 68 m below seafloor (mbsf). These sediment depths, respectively, correspond to the fringes of oxygen penetration from overlying seawater in the top of the sediment column and upward migration of oxygen from oxic seawater from the basalt aquifer below the sediment. Here we report the enrichment, isolation, initial characterization and genomes of three isolated aerobic heterotrophs from North Pond sediments; an Arthrobacter species from 4 mbsf, and Paracoccus and Pseudomonas species from 68 mbsf. These cultivated bacteria are represented in the amplicon 16S rRNA gene libraries created from whole sediments, albeit at low (up to 2%) relative abundance. We provide genomic evidence from our isolates demonstrating that the Arthrobacter and Pseudomonas isolates have the potential to respire nitrate and oxygen, though dissimilatory nitrate reduction could not be confirmed in laboratory cultures. The cultures from this study represent members of abundant phyla, as determined by amplicon sequencing of environmental DNA extracts, and allow for further studies into geochemical factors impacting life in the deep subsurface. PMID:27242705

  18. Deep Subsurface Life from North Pond: Enrichment, Isolation, Characterization and Genomes of Heterotrophic Bacteria.

    PubMed

    Russell, Joseph A; León-Zayas, Rosa; Wrighton, Kelly; Biddle, Jennifer F

    2016-01-01

    Studies of subsurface microorganisms have yielded few environmentally relevant isolates for laboratory studies. In order to address this lack of cultivated microorganisms, we initiated several enrichments on sediment and underlying basalt samples from North Pond, a sediment basin ringed by basalt outcrops underlying an oligotrophic water-column west of the Mid-Atlantic Ridge at 22°N. In contrast to anoxic enrichments, growth was observed in aerobic, heterotrophic enrichments from sediment of IODP Hole U1382B at 4 and 68 m below seafloor (mbsf). These sediment depths, respectively, correspond to the fringes of oxygen penetration from overlying seawater in the top of the sediment column and upward migration of oxygen from oxic seawater from the basalt aquifer below the sediment. Here we report the enrichment, isolation, initial characterization and genomes of three isolated aerobic heterotrophs from North Pond sediments; an Arthrobacter species from 4 mbsf, and Paracoccus and Pseudomonas species from 68 mbsf. These cultivated bacteria are represented in the amplicon 16S rRNA gene libraries created from whole sediments, albeit at low (up to 2%) relative abundance. We provide genomic evidence from our isolates demonstrating that the Arthrobacter and Pseudomonas isolates have the potential to respire nitrate and oxygen, though dissimilatory nitrate reduction could not be confirmed in laboratory cultures. The cultures from this study represent members of abundant phyla, as determined by amplicon sequencing of environmental DNA extracts, and allow for further studies into geochemical factors impacting life in the deep subsurface. PMID:27242705

  19. Deep Subsurface Life from North Pond: Enrichment, Isolation, Characterization and Genomes of Heterotrophic Bacteria.

    PubMed

    Russell, Joseph A; León-Zayas, Rosa; Wrighton, Kelly; Biddle, Jennifer F

    2016-01-01

    Studies of subsurface microorganisms have yielded few environmentally relevant isolates for laboratory studies. In order to address this lack of cultivated microorganisms, we initiated several enrichments on sediment and underlying basalt samples from North Pond, a sediment basin ringed by basalt outcrops underlying an oligotrophic water-column west of the Mid-Atlantic Ridge at 22°N. In contrast to anoxic enrichments, growth was observed in aerobic, heterotrophic enrichments from sediment of IODP Hole U1382B at 4 and 68 m below seafloor (mbsf). These sediment depths, respectively, correspond to the fringes of oxygen penetration from overlying seawater in the top of the sediment column and upward migration of oxygen from oxic seawater from the basalt aquifer below the sediment. Here we report the enrichment, isolation, initial characterization and genomes of three isolated aerobic heterotrophs from North Pond sediments; an Arthrobacter species from 4 mbsf, and Paracoccus and Pseudomonas species from 68 mbsf. These cultivated bacteria are represented in the amplicon 16S rRNA gene libraries created from whole sediments, albeit at low (up to 2%) relative abundance. We provide genomic evidence from our isolates demonstrating that the Arthrobacter and Pseudomonas isolates have the potential to respire nitrate and oxygen, though dissimilatory nitrate reduction could not be confirmed in laboratory cultures. The cultures from this study represent members of abundant phyla, as determined by amplicon sequencing of environmental DNA extracts, and allow for further studies into geochemical factors impacting life in the deep subsurface.

  20. Aquatic Sediments.

    ERIC Educational Resources Information Center

    Sanville, W. D.; And Others

    1978-01-01

    Presents a literature review of aquatic sediments and its effect upon water quality, covering publications of 1976-77. This review includes: (1) sediment water interchange; (2) chemical and physical characterization; and (3) heavy water in sediments. A list of 129 references is also presented. (HM)

  1. SUBSURFACE VISUAL ALARM SYSTEM ANALYSIS

    SciTech Connect

    D.W. Markman

    2001-08-06

    The ''Subsurface Fire Hazard Analysis'' (CRWMS M&O 1998, page 61), and the document, ''Title III Evaluation Report for the Surface and Subsurface Communication System'', (CRWMS M&O 1999a, pages 21 and 23), both indicate the installed communication system is adequate to support Exploratory Studies Facility (ESF) activities with the exception of the mine phone system for emergency notification purposes. They recommend the installation of a visual alarm system to supplement the page/party phone system The purpose of this analysis is to identify data communication highway design approaches, and provide justification for the selected or recommended alternatives for the data communication of the subsurface visual alarm system. This analysis is being prepared to document a basis for the design selection of the data communication method. This analysis will briefly describe existing data or voice communication or monitoring systems within the ESF, and look at how these may be revised or adapted to support the needed data highway of the subsurface visual alarm. system. The existing PLC communication system installed in subsurface is providing data communication for alcove No.5 ventilation fans, south portal ventilation fans, bulkhead doors and generator monitoring system. It is given that the data communication of the subsurface visual alarm system will be a digital based system. It is also given that it is most feasible to take advantage of existing systems and equipment and not consider an entirely new data communication system design and installation. The scope and primary objectives of this analysis are to: (1) Briefly review and describe existing available data communication highways or systems within the ESF. (2) Examine technical characteristics of an existing system to disqualify a design alternative is paramount in minimizing the number of and depth of a system review. (3) Apply general engineering design practices or criteria such as relative cost, and degree of

  2. Environmental parameters controlling microbial activities in terrestrial subsurface environments

    SciTech Connect

    Kieft, T.L.

    1990-01-01

    This project was begun in July 1988 as part of Phase I of the Deep Microbiology Subprogram. At this time, the Subprogram was preparing for sampling near the Savannah River Site (SRS) from what was being termed the Investigator's Hole.'' This was the fourth hole drilled for sampling in the coastal plain sediments at a site near the SRS. Since there was a possibility of sampling from the saline Triassic basin in the deeper regions in this fourth hole, there was particular interest in quantifying halotolerant microorganisms from these samples and in determining the responses of subsurface microbes to a range of soft concentrations. Further interest in the soft tolerances of microbes from these coastal sediments arose from the fact that all of these sediments were deposited under marine conditions. It was also anticipated that samples would be available from the shallow unsaturated (vadose) zone at this site, so there was interest in quantifying microbial responses to matric water potential as well as solute water potential. The initial objectives of this research project were to: characterize microbial communities in a saline aquifer; determine the potential for microbial metabolism of selected organic compounds in a saline aquifers; characterize microbial communities in unsaturated subsurface materials (vadose zones); and determine the potential for microbial metabolism of selected organic compounds in unsaturated subsurface materials (vadose zones). Samples were collected from the borehole during a period extending from August to October 1988. A total of nine samples were express shipped to New Mexico Tech for analyses. These were all saturated zone samples from six different geological formations. Water contents and water potentials were measured at the time of sample arrival.

  3. The genome of Geobacter bemidjiensis, exemplar for the subsurface clade of Geobacter species that predominate in Fe(III)-reducing subsurface environments

    SciTech Connect

    Aklujkar, Muktak; Young, Nelson D; Holmes, Dawn; Chavan, Milind; Risso, Carla; Kiss, Hajnalka; Han, Cliff; Land, Miriam L; Lovley, Derek

    2010-01-01

    Background. Geobacter species in a phylogenetic cluster known as subsurface clade 1 are often the predominant microorganisms in subsurface environments in which Fe(III) reduction is the primary electron-accepting process. Geobacter bemidjiensis, a member of this clade, was isolated from hydrocarbon-contaminated subsurface sediments in Bemidji, Minnesota, and is closely related to Geobacter species found to be abundant at other subsurface sites. This study examines whether there are significant differences in the metabolism and physiology of G. bemidjiensis compared to non-subsurface Geobacter species. Results. Annotation of the genome sequence of G. bemidjiensis indicates several differences in metabolism compared to previously sequenced non-subsurface Geobacteraceae, which will be useful for in silico metabolic modeling of subsurface bioremediation processes involving Geobacter species. Pathways can now be predicted for the use of various carbon sources such as propionate by G. bemidjiensis. Additional metabolic capabilities such as carbon dioxide fixation and growth on glucose were predicted from the genome annotation. The presence of different dicarboxylic acid transporters and two oxaloacetate decarboxylases in G. bemidjiensis may explain its ability to grow by disproportionation of fumarate. Although benzoate is the only aromatic compound that G. bemidjiensis is known or predicted to utilize as an electron donor and carbon source, the genome suggests that this species may be able to detoxify other aromatic pollutants without degrading them. Furthermore, G. bemidjiensis is auxotrophic for 4-aminobenzoate, which makes it the first Geobacter species identified as having a vitamin requirement. Several features of the genome indicated that G. bemidjiensis has enhanced abilities to respire, detoxify and avoid oxygen. Conclusion. Overall, the genome sequence of G. bemidjiensis offers surprising insights into the metabolism and physiology of Geobacteraceae in

  4. RADIOIODINE GEOCHEMISTRY IN THE SRS SUBSURFACE ENVIRONMENT

    SciTech Connect

    Kaplan, D.; Emerson, H.; Powell, B.; Roberts, K.; Zhang, S.; Xu, C.; Schwer, K.; Li, H.; Ho, Y.; Denham, M.; Yeager, C.; Santschi, P.

    2013-05-16

    Iodine-129 is one of the key risk drivers for several Savannah River Site (SRS) performance assessments (PA), including that for the Low-Level Waste Disposal Facility in E-Area. In an effort to reduce the uncertainty associated with the conceptual model and the input values used in PA, several studies have recently been conducted dealing with radioiodine geochemistry at the SRS. The objective of this report was to review these recent studies and evaluate their implications on SRS PA calculations. For the first time, these studies measured iodine speciation in SRS groundwater and provided technical justification for assuming the presence of more strongly sorbing species (iodate and organo-iodine), and measured greater iodine sediment sorption when experiments included these newly identified species; specifically they measured greater sorption coefficients (K{sub d} values: the concentration ratio of iodine on the solid phase divided by the concentration in the aqueous phase). Based on these recent studies, new best estimates were proposed for future PA calculations. The new K{sub d} values are greater than previous recommended values. These proposed K{sub d} values reflect a better understanding of iodine geochemistry in the SRS subsurface environment, which permits reducing the associated conservatism included in the original estimates to account for uncertainty. Among the key contributing discoveries supporting the contention that the K{sub d} values should be increased are that: 1) not only iodide (I{sup -}), but also the more strongly sorbing iodate (IO{sub 3}{sup -}) species exists in SRS groundwater (average total iodine = 15% iodide, 42% iodate, and 43% organoiodine), 2) when iodine was added as iodate, the measured K{sub d} values were 2 to 6 times greater than when the iodine was added as iodide, and perhaps most importantly, 3) higher desorption (10 to 20 mL/g) than (ad)sorption (all previous studies) K{sub d} values were measured. The implications of this

  5. Active Marine Subsurface Bacterial Population Composition in Low Organic Carbon Environments from IODP Expedition 320

    NASA Astrophysics Data System (ADS)

    Shepard, A.; Reese, B. K.; Mills, H. J.; IODP Expedition 320 Shipboard Science Party

    2011-12-01

    The marine subsurface environment contains abundant and active microorganisms. These microbial populations are considered integral players in the marine subsurface biogeochemical system with significance in global geochemical cycles and reservoirs. However, variations in microbial community structure, activity and function associated with the wide-ranging sedimentary and geochemical environments found globally have not been fully resolved. Integrated Ocean Drilling Program Expedition 320 recovered sediments from site U1332. Two sampling depths were selected for analysis that spanned differing lithological units in the sediment core. Sediments were composed of mostly clay with zeolite minerals at 8 meters below sea floor (mbsf). At 27 mbsf, sediments were composed of alternating clayey radiolarian ooze and nannofossil ooze. The concentration of SO42- had little variability throughout the core and the concentration of Fe2+ remained close to, or below, detection limits (0.4 μM). Total organic carbon content ranged from a low of 0.03 wt% to a high of 0.07 wt% between 6 and 30 mbsf providing an opportunity to evaluate marine subsurface microbial communities under extreme electron donor limiting conditions. The metabolically active fraction of the bacterial population was isolated by the extraction and amplification of 16S ribosomal RNA. Pyrosequencing of 16S rRNA transcripts and subsequent bioinformatic analyses provided a robust data set (15,931 total classified sequences) to characterize the community at a high resolution. As observed in other subsurface environments, the overall diversity of active bacterial populations decreased with depth. The population shifted from a diverse but evenly distributed community at approximately 8 mbsf to a Firmicutes dominated population at 27 mbsf (80% of sequences). A total of 95% of the sequences at 27 mbsf were grouped into three genera: Lactobacillus (phylum Firmicutes) at 80% of the total sequences, Marinobacter (phylum

  6. Method of installing subsurface barrier

    DOEpatents

    Nickelson, Reva A.; Richardson, John G.; Kostelnik, Kevin M.; Sloan, Paul A.

    2007-10-09

    Systems, components, and methods relating to subterranean containment barriers. Laterally adjacent tubular casings having male interlock structures and multiple female interlock structures defining recesses for receiving a male interlock structure are used to create subterranean barriers for containing and treating buried waste and its effluents. The multiple female interlock structures enable the barriers to be varied around subsurface objects and to form barrier sidewalls. The barrier may be used for treating and monitoring a zone of interest.

  7. Deep subsurface life from North Pond: Enrichment, isolation, characterization and genomes of heterotrophic bacteria

    DOE PAGES

    Russell, Joseph A.; Leon-Zayas, Rosa; Wrighton, Kelly; Biddle, Jennifer F.

    2016-05-10

    Studies of subsurface microorganisms have yielded few environmentally relevant isolates for laboratory studies. In order to address this lack of cultivated microorganisms, we initiated several enrichments on sediment and underlying basalt samples from North Pond, a sediment basin ringed by basalt outcrops underlying an oligotrophic watercolumn west of the Mid-Atlantic Ridge at 22° N. In contrast to anoxic enrichments, growth was observed in aerobic, heterotrophic enrichments from sediment of IODP Hole U1382B at 4 and 68 m below seafloor (mbsf). These sediment depths, respectively, correspond to the fringes of oxygen penetration from overlying seawater in the top of the sedimentmore » column and upward migration of oxygen from oxic seawater from the basalt aquifer below the sediment. Here we report the enrichment, isolation, initial characterization and genomes of three isolated aerobic heterotrophs from North Pond sediments; an Arthrobacter species from 4 mbsf, and Paracoccus and Pseudomonas species from 68 mbsf. These cultivated bacteria are represented in the amplicon 16S rRNA gene libraries created from whole sediments, albeit at low (up to 2%) relative abundance. We provide genomic evidence from our isolates demonstrating that the Arthrobacter and Pseudomonas isolates have the potential to respire nitrate and oxygen, though dissimilatory nitrate reduction could not be confirmed in laboratory cultures. Furthermore, the cultures from this study represent members of abundant phyla, as determined by amplicon sequencing of environmental DNA extracts, and allow for further studies into geochemical factors impacting life in the deep subsurface.« less

  8. INL Subsurface Wireless Sensor Platform

    SciTech Connect

    Dennis C. Kunerth; John M. Svoboda; James T. Johnson

    2005-10-01

    The Idaho National Laboratory is developing a versatile micro-power sensor interface platform for periodic subsurface sensing of environmental variables important to waste disposal sites such as volumetric moisture, water potential, and temperature. The key characteristics of the platform architecture are that the platform is passive until externally energized --no internal power source is required -- and that it communicates with a "reader" via short-range telemetry - no wires penetrate the subsurface. Other significant attributes include the potential for a long service life and a compact size that makes it well suited for retrofitting existing landfill structures. Functionally, the sensor package is "read" by a short-range induction coil that activates and powers the sensor platform as well as detects the sensor output via a radio frequency signal generated by the onboard programmable interface controller microchip. As a result, the platform has a functional subsurface communication range of approximately 10 to 12 ft. and can only accept sensors that require low power to operate.

  9. Geophysical characterization of subsurface barriers

    SciTech Connect

    Borns, D.J.

    1995-08-01

    An option for controlling contaminant migration from plumes and buried waste sites is to construct a subsurface barrier of a low-permeability material. The successful application of subsurface barriers requires processes to verify the emplacement and effectiveness of barrier and to monitor the performance of a barrier after emplacement. Non destructive and remote sensing techniques, such as geophysical methods, are possible technologies to address these needs. The changes in mechanical, hydrologic and chemical properties associated with the emplacement of an engineered barrier will affect geophysical properties such a seismic velocity, electrical conductivity, and dielectric constant. Also, the barrier, once emplaced and interacting with the in situ geologic system, may affect the paths along which electrical current flows in the subsurface. These changes in properties and processes facilitate the detection and monitoring of the barrier. The approaches to characterizing and monitoring engineered barriers can be divided between (1) methods that directly image the barrier using the contrasts in physical properties between the barrier and the host soil or rock and (2) methods that reflect flow processes around or through the barrier. For example, seismic methods that delineate the changes in density and stiffness associated with the barrier represents a direct imaging method. Electrical self potential methods and flow probes based on heat flow methods represent techniques that can delineate the flow path or flow processes around and through a barrier.

  10. 3-D modeling of water balance and soil erosion in a clayey subsurface drained agricultural field in boreal climate

    NASA Astrophysics Data System (ADS)

    Turunen, M.; Warsta, L.; Koivusalo, H. J.; Paasonen-Kivekäs, M.; Nurminen, J.; Myllys, M.; Alakukku, L.; Äijö, H.; Puustinen, M.

    2012-12-01

    Fluxes of nutrients and other substances from cultivated fields cause eutrophication and deterioration of water quality in aquatic ecosystems worldwide. In order to develop effective strategies to control the environmental impacts of crop cultivation, it is crucial to identify the main transport pathways and the effects of different water management methods on the loads. Reduction of sediment loads is essential since sediment particles typically carry nutrients (especially sorbed phosphorus) and other potentially harmful substances, e.g. pesticides, from the fields to the adjacent surface waters. The novel part of this study was the investigation of suspended sediment transport in soil macropores to the subsurface drains and to the deep groundwater. We applied a 3-D distributed dual-permeability model (FLUSH) using a dataset collected from a subsurface drained, clayey agricultural field (15 ha) to holistically assess water balance, soil erosion and sediment transport from the field to an adjacent stream. The data set included five years of hydrological and water quality measurements from four intensively monitored field sections with different soil properties, topography, drainage systems (drain spacing and drain depth), drain installation methods (trenchless and trench drainage) and drain envelope materials (gravel and fiber). The 3-D model allowed us to quantify how soil erosion and sediment transport differed between the field sections within the field area. The simulations were conducted during snow- and frost-free periods. The simulation results include closure of water balance of the cultivated field, distribution of soil erosion and sediment transport within the field area and the effects of different subsurface drainage systems on sediment loads. The 3-D dual-permeability subsurface flow model was able to reproduce the measured drainflows and sediment fluxes in the clayey field and according to the simulations over 90% of drainflow waters were conveyed to

  11. Sources of suspended sediment in the Lower Roanoke River, NC

    NASA Astrophysics Data System (ADS)

    Jalowska, A. M.; McKee, B. A.; Rodriguez, A. B.; Laceby, J. P.

    2015-12-01

    The Lower Roanoke River, NC, extends 220 km from the fall line to the bayhead delta front in the Albemarle Sound. The Lower Roanoke is almost completely disconnected from the upper reaches by a series of dams, with the furthest downstream dam located at the fall line. The dams effectively restrict the suspended sediment delivery from headwaters, making soils and sediments from the Lower Roanoke River basin, the sole source of suspended sediment. In flow-regulated rivers, bank erosion, especially mass wasting, is the major contributor to the suspended matter. Additional sources of the suspended sediment considered in this study are river channel, surface soils, floodplain surface sediments, and erosion of the delta front and prodelta. Here, we examine spatial and temporal variations in those sources. This study combined the use of flow and grain size data with a sediment fingerprinting method, to examine the contribution of surface and subsurface sediments to the observed suspended sediment load along the Lower Roanoke River. The fingerprinting method utilized radionuclide tracers 210Pb (natural atmospheric fallout), and 137Cs (produced by thermonuclear bomb testing). The contributions of surface and subsurface sources to the suspended sediment were calculated with 95% confidence intervals using a Monte-Carlo numerical mixing model. Our results show that with decreasing river slope and changing hydrography along the river, the contribution of surface sediments increases and becomes a main source of sediments in the Roanoke bayhead delta. At the river mouth, the surface sediment contribution decreases and is replaced by sediments eroded from the delta front and prodelta. The area of high surface sediment contribution is within the middle and upper parts of the delta, which are considered net depositional. Our study demonstrates that floodplains, often regarded to be a sediment sink, are also a sediment source, and they should be factored into sediment, carbon and

  12. 46 CFR 308.518 - Standard optional endorsement No. 1, Form MA-300-A.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 8 2014-10-01 2014-10-01 false Standard optional endorsement No. 1, Form MA-300-A. 308.518 Section 308.518 Shipping MARITIME ADMINISTRATION, DEPARTMENT OF TRANSPORTATION EMERGENCY OPERATIONS WAR RISK INSURANCE War Risk Cargo Insurance Open Policy War Risk Cargo Insurance §...

  13. Laboratory and Field Evidence for Long-Term Starvation Survival of Microorganisms in Subsurface Terrestrial Environments

    SciTech Connect

    Kieft, T.L.; Murphy, E.M.; Amy, P.S.; Haldeman, D.L.; Ringelberg, D. B. |

    1997-12-31

    BIOGEOCHEMICAL MODELING OF GROUNDWATER FLOW AND NUTRIENT FLUX IN SUBSURFACE ENVIRONMENTS INDICATES THAT INHABITANT MICROORGANISMS EXPERIENCE SEVERE NUTRIENT LIMITATION. USING LABORATORY AND FIELD METHODS, WE HAVE BEEN TESTING STARVATION SURVIVAL IN SUBSURFACE MICROORGANISMS. IN MICROCOSM EXPERIMENTS, WE HAVE SHOWN THAT STRAINS OF TWO COMMONLY ISOLATED SUBSURFACE GENERA, ARTHROBACTER AND PSEUDOMONAS, ARE ABLE TO MAINTAIN VIABILITY IN LOW-NUTRIENT, NATURAL SUBSURFACE SEDIMENTS FOR OVER ONE YEAR. THESE NON-SPORE-FORMING BACTERIA UNDERGO RAPID INITIAL MINIATURIZATION FOLLOWED BY A STABILIZATION OF CELL SIZE. MEMBRANE LIPID PHOSPHOLIPID FATTY ACID (PLFA) PROFILES OF THE PSEUDOMONAS ARE CONSISTENT WITH ADAPTATION TO NUTRIENT STRESS; ARTHROBACTER APPARENTLY RESPONDS TO NUTRIENT DEPRIVATION WITHOUT ALTERING MEMBRANE PLFA. TO TEST SURVIVABILITY OF MICROORGANISMS OVER A GEOLOGIC TIME SCALE, WE CHARACTERIZED MICROBIAL COMMUNITIES IN A SEQUENCE OF UNSATURATED SEDIMENTS RANGING IN AGE FROM MODEM TO {gt}780,000 years. Sediments were relatively uniform silts in Eastern Washington State. Porewater ages at depth (measured by the chloride mass-balance approach) were as old as 3,600 years. Microbial abundance, biomass, and activities (measured by direct counts, culture counts, total PLFAs, and radiorespirometry) declined with sediment age. The pattern is consistent with laboratory microcosm studies of Microbial survival: rapid short-term change followed by long-term survival of a proportion of cells. Even the oldest sediments evinced a small but viable Microbial community. Microbial survival appeared to be a function of sediment age. Porewater age appeared to influence the markup of surviving communities, as indicated by PLFA profiles. Sites with different Porewater recharge rates and patterns of Pleistocene flooding had different communities.

  14. Laboratory and field evidence for long-term starvation survival of microorganisms in subsurface terrestrial environments

    NASA Astrophysics Data System (ADS)

    Kieft, Thomas L.; Murphy, Ellyn M.; Amy, P. S.; Haldeman, D. L.; Ringelberg, David B.; White, David C.

    1997-07-01

    Biogeochemical modeling of groundwater flow and nutrient flux in subsurface environments indicates that inhabitant microorganisms experience severe nutrient limitation. Using laboratory and field methods, we have been testing starvation survival in subsurface microorganisms. In microcosm experiments, we have shown that strains of two commonly isolated subsurface genera, Arthrobacter and Pseudomonas, are able to maintain viability in low-nutrient, natural subsurface sediments for over one year. These non- spore-forming bacteria undergo rapid initial miniaturization followed by a stabilization of cell size. Membrane lipid phospholipid fatty acid (PLFA) profiles of the Pseudomonas are consistent with adaptation to nutrient stress; Arthrobacter apparently responds to nutrient deprivation without altering membrane PLFAs. To test survivability of microorganisms over a geologic time scale, we characterized microbial communities in a sequence of unsaturated sediments ranging in age from modern to > 780,000 years. Sediments were relatively uniform silts in eastern Washington State. Porewater ages at depth (measured by the chloride mass- balance approach) were as old as 3,600 years. Microbial abundance, biomass, and activities (measured by direct counts, culture counts, total PLFAs, and radiorespirometry) declined with sediment age. The pattern is consistent with laboratory microcosm studies of microbial survival: rapid short-term change followed by long-term survival of a proportion of cells. Even the oldest sediments evinced a small but viable microbial community. Microbial survival appeared to be a function of sediment age. Porewater age appeared to influence the makeup of surviving communities, as indicated by PLFA profiles. Sites with different porewater recharge rates and patterns of Pleistocene flooding had different communities. These and other studies provide evidence that microorganisms can survive nutrient limitation for geologic time periods.

  15. Geomorphic factors related to the persistence of subsurface oil from the Exxon Valdez oil spill

    USGS Publications Warehouse

    Nixon, Zachary; Michel, Jacqueline; Hayes, Miles O.; Irvine, Gail V.; Short, Jeffrey

    2013-01-01

    Oil from the 1989 Exxon Valdez oil spill has persisted along shorelines of Prince William Sound, Alaska, for more than two decades as both surface and subsurface oil residues. To better understand the distribution of persistent subsurface oil and assess the potential need for further restoration, a thorough and quantitative understanding of the geomorphic factors controlling the presence or absence of subsurface oil is required. Data on oiling and geomorphic features were collected at 198 sites in Prince William Sound to identify and quantify the relationships among these geomorphic factors and the presence and absence of persistent subsurface oil. Geomorphic factors associated with the presence of subsurface oil were initial oil exposure, substrate permeability, topographic slope, low exposure to waves, armoring on gravel beaches, tombolos, natural breakwaters, and rubble accumulations. Geomorphic factors associated with the absence of subsurface oil were impermeable bedrock; platforms with thin sediment veneer; fine-grained, well-sorted gravel beaches with no armor; and low-permeability, raised bay-bottom beaches. Relationships were found between the geomorphic and physical site characteristics and the likelihood of encountering persistent subsurface oiling at those sites. There is quantitative evidence of more complex interactions between the overall wave energy incident at a site and the presence of fine-scale geomorphic features that may have provided smaller, local wave energy sheltering of oil. Similarly, these data provide evidence for interactions between the shoreline slope and the presence of angular rubble, with decreased likelihood for encountering subsurface oil at steeply sloped sites except at high-angle sheltered rubble shoreline locations. These results reinforce the idea that the interactions of beach permeability, stability, and site-specific wave exposure are key drivers for subsurface oil persistence in exposed and intermittently exposed mixed

  16. Drilling Automation Demonstrations in Subsurface Exploration for Astrobiology

    NASA Technical Reports Server (NTRS)

    Glass, Brian; Cannon, H.; Lee, P.; Hanagud, S.; Davis, K.

    2006-01-01

    This project proposes to study subsurface permafrost microbial habitats at a relevant Arctic Mars-analog site (Haughton Crater, Devon Island, Canada) while developing and maturing the subsurface drilling and drilling automation technologies that will be required by post-2010 missions. It builds on earlier drilling technology projects to add permafrost and ice-drilling capabilities to 5m with a lightweight drill that will be automatically monitored and controlled in-situ. Frozen cores obtained with this drill under sterilized protocols will be used in testing three hypotheses pertaining to near-surface physical geology and ground H2O ice distribution, viewed as a habitat for microbial life in subsurface ice and ice-consolidated sediments. Automation technologies employed will demonstrate hands-off diagnostics and drill control, using novel vibrational dynamical analysis methods and model-based reasoning to monitor and identify drilling fault states before and during faults. Three field deployments, to a Mars-analog site with frozen impact crater fallback breccia, will support science goals, provide a rigorous test of drilling automation and lightweight permafrost drilling, and leverage past experience with the field site s particular logistics.

  17. Deep sequencing of subseafloor eukaryotic rRNA reveals active Fungi across marine subsurface provinces.

    PubMed

    Orsi, William; Biddle, Jennifer F; Edgcomb, Virginia

    2013-01-01

    The deep marine subsurface is a vast habitat for microbial life where cells may live on geologic timescales. Because DNA in sediments may be preserved on long timescales, ribosomal RNA (rRNA) is suggested to be a proxy for the active fraction of a microbial community in the subsurface. During an investigation of eukaryotic 18S rRNA by amplicon pyrosequencing, unique profiles of Fungi were found across a range of marine subsurface provinces including ridge flanks, continental margins, and abyssal plains. Subseafloor fungal populations exhibit statistically significant correlations with total organic carbon (TOC), nitrate, sulfide, and dissolved inorganic carbon (DIC). These correlations are supported by terminal restriction length polymorphism (TRFLP) analyses of fungal rRNA. Geochemical correlations with fungal pyrosequencing and TRFLP data from this geographically broad sample set suggests environmental selection of active Fungi in the marine subsurface. Within the same dataset, ancient rRNA signatures were recovered from plants and diatoms in marine sediments ranging from 0.03 to 2.7 million years old, suggesting that rRNA from some eukaryotic taxa may be much more stable than previously considered in the marine subsurface.

  18. Deep Sequencing of Subseafloor Eukaryotic rRNA Reveals Active Fungi across Marine Subsurface Provinces

    PubMed Central

    Orsi, William; Biddle, Jennifer F.; Edgcomb, Virginia

    2013-01-01

    The deep marine subsurface is a vast habitat for microbial life where cells may live on geologic timescales. Because DNA in sediments may be preserved on long timescales, ribosomal RNA (rRNA) is suggested to be a proxy for the active fraction of a microbial community in the subsurface. During an investigation of eukaryotic 18S rRNA by amplicon pyrosequencing, unique profiles of Fungi were found across a range of marine subsurface provinces including ridge flanks, continental margins, and abyssal plains. Subseafloor fungal populations exhibit statistically significant correlations with total organic carbon (TOC), nitrate, sulfide, and dissolved inorganic carbon (DIC). These correlations are supported by terminal restriction length polymorphism (TRFLP) analyses of fungal rRNA. Geochemical correlations with fungal pyrosequencing and TRFLP data from this geographically broad sample set suggests environmental selection of active Fungi in the marine subsurface. Within the same dataset, ancient rRNA signatures were recovered from plants and diatoms in marine sediments ranging from 0.03 to 2.7 million years old, suggesting that rRNA from some eukaryotic taxa may be much more stable than previously considered in the marine subsurface. PMID:23418556

  19. Aquatic sediments

    SciTech Connect

    Bonner, J.S.; Autenrieth, R.L.; Schreiber, L. )

    1990-06-01

    The authors present a literature review concerning sediment properties, interactions, and conditions. Topics of discussion include the following: biological activity and toxicity; nutrients; metals; organic compounds; dredging; radionuclides; oxygen demand and organic carbon; mathematical modeling; sediment transport and suspension; and paleolimnology.

  20. Azaarenes in Puget sound sediments

    NASA Astrophysics Data System (ADS)

    Furlong, Edward T.; Carpenter, Roy

    1982-08-01

    The first quantitative measurements of azaarenes in marine sediments are reported for Puget Sound, in northwestern Washington State, U.S.A. Two- to four-ring azaarenes, in concentrations as low as 50 ppb (relative to organic carbon), are measured in 210Pb dated sediments using glass capillary gas chromatography combined with nitrogen-selective detection. Azaarene distributions are geographically and temporally variable. Azaarene distributions in upper sediment layers suggest that total azaarene concentrations are related to proximity to urban areas, and may be anthropogenically derived. Subsurface maxima between 6 and 17 cm in several cores resemble similar maxima in PAH and organo-sulfur compounds. Trace quantities of azaarenes present in sediments, deposited prior to urbanization of the Puget Sound region, suggest low-level natural azaarene sources. One core containing particulate coal produced a concentrated and complex azaarene mixture, suggesting either introduction of mined coal or erosion of regional coal deposits. Analyses of possible azaarene sources indicate that although azaarene compositions vary between sources, coal azaarenes can be distinguished from petroleum azaarenes by their ratios of 2-ring to 3-ring azaarenes, and may identify predominant azaarene inputs in environmental samples. Gross differences in azaarene composition exist between European and American air particulates and sediments, suggesting differences in azaarene sources.

  1. The layered subsurface - periglacial slope deposits as crucial elements for soil formation and variability

    NASA Astrophysics Data System (ADS)

    Völkel, Jörg; Huber, Juliane

    2014-05-01

    Still most concepts of soil formation, weathering production rates and weathering front ideas are dealing with a monolayered near-surface underground and subsoil. At best a line is given on so-called moved regolith. In fact the subsurface is often characterized by stratified and multilayered slope deposits with thicknesses exceeding 1 m. These stratified slope sediments play a significant role in the nature of the physical and chemical properties as well as on soil forming processes. Examples are given for sediment sourced chemical elements and common clay minerals, and the significance of slope sediments as both barriers and pathways for interflow that moves through the stratified sediments. The stratified subsurface is often datable by numeric age techniques (OSL) showing up how sediment features contradict weathering effects and meaning e.g. for soil genesis. In the mid latitudes, geomorphic and sedimentologic evidence supports a periglacial origin, involving solifluction, for the origin of these slope deposits. The study areas are situated within the Colorado Front Range, U.S. and the Bavarian Forest, Germany. The projects are currently financed and supported by the German Science Foundation DFG. Literature: Völkel, J., Huber, J. & Leopold, M. (2011): Significance of slope sediments layering on physical characteristics and interflow within the Critical Zone… - Applied Geochemistry 26: 143-145.

  2. Introduction: energy and the subsurface.

    PubMed

    Christov, Ivan C; Viswanathan, Hari S

    2016-10-13

    This theme issue covers topics at the forefront of scientific research on energy and the subsurface, ranging from carbon dioxide (CO2) sequestration to the recovery of unconventional shale oil and gas resources through hydraulic fracturing. As such, the goal of this theme issue is to have an impact on the scientific community, broadly, by providing a self-contained collection of articles contributing to and reviewing the state-of-the-art of the field. This collection of articles could be used, for example, to set the next generation of research directions, while also being useful as a self-study guide for those interested in entering the field. Review articles are included on the topics of hydraulic fracturing as a multiscale problem, numerical modelling of hydraulic fracture propagation, the role of computational sciences in the upstream oil and gas industry and chemohydrodynamic patterns in porous media. Complementing the reviews is a set of original research papers covering growth models for branched hydraulic crack systems, fluid-driven crack propagation in elastic matrices, elastic and inelastic deformation of fluid-saturated rock, reaction front propagation in fracture matrices, the effects of rock mineralogy and pore structure on stress-dependent permeability of shales, topographic viscous fingering and plume dynamics in porous media convection.This article is part of the themed issue 'Energy and the subsurface'. PMID:27597784

  3. Introduction: energy and the subsurface.

    PubMed

    Christov, Ivan C; Viswanathan, Hari S

    2016-10-13

    This theme issue covers topics at the forefront of scientific research on energy and the subsurface, ranging from carbon dioxide (CO2) sequestration to the recovery of unconventional shale oil and gas resources through hydraulic fracturing. As such, the goal of this theme issue is to have an impact on the scientific community, broadly, by providing a self-contained collection of articles contributing to and reviewing the state-of-the-art of the field. This collection of articles could be used, for example, to set the next generation of research directions, while also being useful as a self-study guide for those interested in entering the field. Review articles are included on the topics of hydraulic fracturing as a multiscale problem, numerical modelling of hydraulic fracture propagation, the role of computational sciences in the upstream oil and gas industry and chemohydrodynamic patterns in porous media. Complementing the reviews is a set of original research papers covering growth models for branched hydraulic crack systems, fluid-driven crack propagation in elastic matrices, elastic and inelastic deformation of fluid-saturated rock, reaction front propagation in fracture matrices, the effects of rock mineralogy and pore structure on stress-dependent permeability of shales, topographic viscous fingering and plume dynamics in porous media convection.This article is part of the themed issue 'Energy and the subsurface'.

  4. Phylogenetic relationships among subsurface microorganisms

    SciTech Connect

    Nierzwicki-Bauer, S.A.

    1991-01-01

    This project involves the development of group specific 16S ribosomal RNA-targeted oligonucleotide hybridization probes for the rapid detection of specific types of subsurface organisms (e.g., groups of microbes that share certain physiological traits). Major accomplishments for the period of 6/91 to 12/1/91 are described. Nine new probes have been synthesized on the basis of published 16S rRNA sequence data from the Ribosomal Database Project. We have initiated rapid screening of many of the subsurface microbial isolates obtained from the P24 borehole at the Savannah River Site. To date, we have screened approximately 50% of the isolates from P24. We have optimized our {und in situ} hybridization technique, and have developed a cell blot hybridization technique to screen 96 samples on a single blot. This is much faster than reading 96 individual slides. Preliminary experiments have been carried out which indicate specific nutrients can be used to amplify rRNA only in those organisms capable of metabolizing those nutrients. 1 tab., 2 figs.

  5. The evolution of cave systems from the surface to subsurface

    SciTech Connect

    Loucks, R.G.; Handford, C.R.

    1996-12-31

    Many carbonate reservoirs are the result of cave-forming processes. The origin and recognition of fractures, breccias, and sediment fills associated with paleocaves were determined through the study of modern and paleocaves systems. Cave formation and destruction are the products of near-surface processes. Near-surface processes include solutional excavation, clastic and chemical sedimentation, and collapse of cave walls and ceilings. Cave sediment is derived from inside and/or outside the system. Depositional mechanisms include suspension, tractional, mass-flow and rock-fall. Collapse of ceilings and walls from chaotic breakdown breccias. These piles can be tens of meters thick and contain large voids and variable amounts of matrix. Cave-roof crackle breccia forms from stress-and tension-related fractures in cave-roof strata. As the cave-bearing strata subside into the subsurface, mechanical compaction increases and restructures the existing breccias and remaining cavities. Fracture porosity increases and breccia and vug porosity decreases. Large cavities collapse forming burial chaotic breakdown breccias. Differentially compacted strata over the collapsed chamber fracture and form burial cave-roof crackle breccias. Continued burial leads to more extensive mechanical compaction causing previously formed clasts to fracture and pack closer together. The resulting product is a rebrecciated chaotic breakdown breccia composed predominantly of small clasts. Rebrecciated blocks are often overprinted by crackling. Subsurface paleocave systems commonly have a complex history with several episodes of fracturing and brecciation. The resulting collapsed-paleocave reservoir targets are not single collapsed passages of tens of feet across, but are homogenized collapsed-cave systems hundreds to several thousand feet across.

  6. The evolution of cave systems from the surface to subsurface

    SciTech Connect

    Loucks, R.G. ); Handford, C.R. )

    1996-01-01

    Many carbonate reservoirs are the result of cave-forming processes. The origin and recognition of fractures, breccias, and sediment fills associated with paleocaves were determined through the study of modern and paleocaves systems. Cave formation and destruction are the products of near-surface processes. Near-surface processes include solutional excavation, clastic and chemical sedimentation, and collapse of cave walls and ceilings. Cave sediment is derived from inside and/or outside the system. Depositional mechanisms include suspension, tractional, mass-flow and rock-fall. Collapse of ceilings and walls from chaotic breakdown breccias. These piles can be tens of meters thick and contain large voids and variable amounts of matrix. Cave-roof crackle breccia forms from stress-and tension-related fractures in cave-roof strata. As the cave-bearing strata subside into the subsurface, mechanical compaction increases and restructures the existing breccias and remaining cavities. Fracture porosity increases and breccia and vug porosity decreases. Large cavities collapse forming burial chaotic breakdown breccias. Differentially compacted strata over the collapsed chamber fracture and form burial cave-roof crackle breccias. Continued burial leads to more extensive mechanical compaction causing previously formed clasts to fracture and pack closer together. The resulting product is a rebrecciated chaotic breakdown breccia composed predominantly of small clasts. Rebrecciated blocks are often overprinted by crackling. Subsurface paleocave systems commonly have a complex history with several episodes of fracturing and brecciation. The resulting collapsed-paleocave reservoir targets are not single collapsed passages of tens of feet across, but are homogenized collapsed-cave systems hundreds to several thousand feet across.

  7. Calculation notes that support accident scenario and consequence development for the subsurface leak remaining subsurface accident

    SciTech Connect

    Ryan, G.W., Westinghouse Hanford

    1996-07-12

    This document supports the development and presentation of the following accident scenario in the TWRS Final Safety Analysis Report: Subsurface Leak Remaining Subsurface. The calculations needed to quantify the risk associated with this accident scenario are included within.

  8. Preliminary Investigation of Linkages Between Arctic Pingos and Subsurface Stratigraphy

    NASA Astrophysics Data System (ADS)

    Casavant, R.; Skirvin, S.; Patel, C.; Burr, D.

    2008-12-01

    This NASA-SETI supported study investigates the distribution of pingos (elliptically-shaped ice-rich topographic mounds) across 2300 square kilometers of the central coastal plain of Arctic Alaska in relation to the shallow geological framework that exists immediately beneath them. Pingos in the central North Slope of Alaska are classified as being of the closed or hydrostatic type. Their genesis is often assigned to freezing and cryogenic uplift of near-surface saturated thaw lake sediments that are exposed as lakes are drained and/or become choked with sediments. Although thaw lakes appear rather ubiquitous across the study area, pingos do not. Pingo distributions can be categorized as either clusters of elements or as relatively dispersed. Spatial statistical analysis reveals that pingo distribution is non-random and clustered. The analysis also took into account that pingo distribution is a function of preferential preservation between modern rivers channels that cross the study area. Pingo distributions and frequency were tested in relation to the location and type of stratigraphic and sedimentological features that characterized the shallow subsurface across the study area. Subsurface interpretation was derived mostly from oil well wireline logs. Gamma ray logs for more than 160 wells were used to define, correlate and assess the connectivity and conductivity of shallow and near-surface stratigraphic units between wells. Assessed also were major facies changes and the type and locations of subsurface structures such as major basement-to-surface faults and folds. The surface and near-surface truncation and subcropping of tilted, alternating units of permeable coarse-grained and confining fine- grained units were also mapped in relation to pingo locations. Preliminary and intriguing findings will be presented which contribute to the hypothesis that pingo genesis, location, and variations in morphology could be, in part, linked to a well-documented and active

  9. A field evaluation of subsurface and surface runoff. II. Runoff processes

    USGS Publications Warehouse

    Pilgrim, D.H.; Huff, D.D.; Steele, T.D.

    1978-01-01

    Combined use of radioisotope tracer, flow rate, specific conductance and suspended-sediment measurements on a large field plot near Stanford, California, has provided more detailed information on surface and subsurface storm runoff processes than would be possible from any single approach used in isolation. Although the plot was surficially uniform, the runoff processes were shown to be grossly nonuniform, both spatially over the plot, and laterally and vertically within the soil. The three types of processes that have been suggested as sources of storm runoff (Horton-type surface runoff, saturated overland flow, and rapid subsurface throughflow) all occurred on the plot. The nonuniformity of the processes supports the partial- and variable-source area concepts. Subsurface storm runoff occurred in a saturated layer above the subsoil horizon, and short travel times resulted from flow through macropores rather than the soil matrix. Consideration of these observations would be necessary for physically realistic modeling of the storm runoff process. ?? 1978.

  10. Microbial processes and subsurface contaminants

    NASA Astrophysics Data System (ADS)

    Molz, Fred J.

    A Chapman Conference entitled “Microbial Processes in the Transport, Fate, and In Situ Treatment of Subsurface Contaminants” was held in Snowbird, Utah, October 1-3, 1986. Members of the program committee and session chairmen were Lenore Clesceri (Rensselaer Polytechnic Institute, Troy, N.Y.), David Gibson (University of Texas, Austin), James Mercer (GeoTrans, Inc., Herndon , Va.), Donald Michelsen (Virginia Polytechnic Institute and State University, Blacksburg), Fred Molz (Auburn University, Auburn, Ala.), Bruce Rittman (University of Illinois, Urbana), Gary Sayler (University of Tennessee, Knoxville), and John T. Wilson (U.S. Environmental Protection Agency, Ada, Okla.). The following report attempts to highlight the six sessions that constituted the conference. For additional information, including a bound summary and abstracts, contact Fred J. Molz, Civil Engineering Department, Auburn University, AL 36849 (telephone: 205-826-4321).

  11. Subsurface Flow and Contaminant Transport

    2000-09-19

    FACT is a transient three-dimensional, finite element code for simulating isothermal groundwater flow, moisture movement, and solute transport in variably and/or fully saturated subsurface porous media. Both single and dual-domain transport formulations are available. Transport mechanisms considered include advection, hydrodynamic dispersion, linear adsorption, mobile/immobile mass transfer and first-order degradation. A wide range of acquifier conditions and remediation systems commonly encountered in the field can be simulated. Notable boundary condition (BC) options include, a combined rechargemore » and drain BC for simulating recirculation wells, and a head dependent well BC that computes flow based on specified drawdown. The code is designed to handle highly heterogenous, multi-layer, acquifer systems in a numerically efficient manner. Subsurface structure is represented with vertically distorted rectangular brick elements in a Cartesian system. The groundwater flow equation is approximated using the Bubnov-Galerkin finite element method in conjunction with an efficient symmetric Preconditioned Conjugate Gradient (PCG) ICCG matrix solver. The solute transport equation is approximated using an upstream weighted residual finite element method designed to alleviate numerical oscillation. An efficient asymmetric PCG (ORTHOMIN) matrix solver is employed for transport. For both the flow and transport equations, element matrices are computed from either influence coefficient formulas for speed, or two point Gauss-Legendre quadrature for accuracy. Non-linear flow problems can be solved using either Newton-Ralphson linearization or Picard iteration, with under-relaxation formulas to further enhance convergence. Dynamic memory allocation is implemented using Fortran 90 constructs. FACT coding is clean and modular.« less

  12. Multiply Methyl-Branched Fatty Acids and Diacids in the Polar Lipids of a Microaerophilic Subsurface Microbial Community

    SciTech Connect

    Hedrick, David B.; Peacock, Aaron D.; Long, Philip E.; White, David C.

    2008-09-01

    A previously unreported series of di- and trimethylated fatty acids, as well as saturated and monounsaturated diacids were identified in polar lipids isolated from environmental subsurface sediment samples. Mechanisms are proposed for their formation, but their origin and role in cell membranes remains unknown.

  13. Immunological techniques as tools to characterize the subsurface microbial community at a trichloroethylene contaminated site

    SciTech Connect

    Fliermans, C.B.; Dougherty, J.M.; Franck, M.M.; McKinzey, P.C.; Hazen, T.C.

    1992-12-31

    Effective in situ bioremediation strategies require an understanding of the effects pollutants and remediation techniques have on subsurface microbial communities. Therefore, detailed characterization of a site`s microbial communities is important. Subsurface sediment borings and water samples were collected from a trichloroethylene (TCE) contaminated site, before and after horizontal well in situ air stripping and bioventing, as well as during methane injection for stimulation of methane-utilizing microorganisms. Subsamples were processed for heterotrophic plate counts, acridine orange direct counts (AODC), community diversity, direct fluorescent antibodies (DFA) enumeration for several nitrogen-transforming bacteria, and Biolog {reg_sign} evaluation of enzyme activity in collected water samples. Plate counts were higher in near-surface depths than in the vadose zone sediment samples. During the in situ air stripping and bioventing, counts increased at or near the saturated zone, remained elevated throughout the aquifer, but did not change significantly after the air stripping. Sporadic increases in plate counts at different depths as well as increased diversity appeared to be linked to differing lithologies. AODCs were orders of magnitude higher than plate counts and remained relatively constant with depth except for slight increases near the surface depths and the capillary fringe. Nitrogen-transforming bacteria, as measured by serospecific DFA, were greatly affected both by the in situ air stripping and the methane injection. Biolog{reg_sign} activity appeared to increase with subsurface stimulation both by air and methane. The complexity of subsurface systems makes the use of selective monitoring tools imperative.

  14. Immunological techniques as tools to characterize the subsurface microbial community at a trichloroethylene contaminated site

    SciTech Connect

    Fliermans, C.B.; Dougherty, J.M.; Franck, M.M.; McKinzey, P.C.; Hazen, T.C.

    1992-01-01

    Effective in situ bioremediation strategies require an understanding of the effects pollutants and remediation techniques have on subsurface microbial communities. Therefore, detailed characterization of a site's microbial communities is important. Subsurface sediment borings and water samples were collected from a trichloroethylene (TCE) contaminated site, before and after horizontal well in situ air stripping and bioventing, as well as during methane injection for stimulation of methane-utilizing microorganisms. Subsamples were processed for heterotrophic plate counts, acridine orange direct counts (AODC), community diversity, direct fluorescent antibodies (DFA) enumeration for several nitrogen-transforming bacteria, and Biolog [reg sign] evaluation of enzyme activity in collected water samples. Plate counts were higher in near-surface depths than in the vadose zone sediment samples. During the in situ air stripping and bioventing, counts increased at or near the saturated zone, remained elevated throughout the aquifer, but did not change significantly after the air stripping. Sporadic increases in plate counts at different depths as well as increased diversity appeared to be linked to differing lithologies. AODCs were orders of magnitude higher than plate counts and remained relatively constant with depth except for slight increases near the surface depths and the capillary fringe. Nitrogen-transforming bacteria, as measured by serospecific DFA, were greatly affected both by the in situ air stripping and the methane injection. Biolog[reg sign] activity appeared to increase with subsurface stimulation both by air and methane. The complexity of subsurface systems makes the use of selective monitoring tools imperative.

  15. Desulfotomaculum spp. and related gram-positive sulfate-reducing bacteria in deep subsurface environments

    PubMed Central

    Aüllo, Thomas; Ranchou-Peyruse, Anthony; Ollivier, Bernard; Magot, Michel

    2013-01-01

    Gram-positive spore-forming sulfate reducers and particularly members of the genus Desulfotomaculum are commonly found in the subsurface biosphere by culture based and molecular approaches. Due to their metabolic versatility and their ability to persist as endospores. Desulfotomaculum spp. are well-adapted for colonizing environments through a slow sedimentation process. Because of their ability to grow autotrophically (H2/CO2) and produce sulfide or acetate, these microorganisms may play key roles in deep lithoautotrophic microbial communities. Available data about Desulfotomaculum spp. and related species from studies carried out from deep freshwater lakes, marine sediments, oligotrophic and organic rich deep geological settings are discussed in this review. PMID:24348471

  16. Fate of Brine Applied to Unpaved Roads at a Radioactive Waste Subsurface Disposal Area

    SciTech Connect

    Larry C. Hull; Carolyn W. Bishop

    2004-02-01

    Between 1984 and 1993, MgCl2 brine was used to suppress dust on unpaved roads at a radioactive waste subsurface disposal area. Because Cl– might enhance corrosion of buried metals in the waste, we investigated the distribution and fate of Cl– in the vadose zone using pore water samples collected from suction lysimeters and soluble salt concentrations extracted from sediment samples. The Cl/Br mass ratio and the total dissolved Cl– concentration of pore water show that brine contamination occurs primarily within 13 m of treated roads, but can extend as much as 30 m laterally in near-surface sedimentary deposits. Within the deep vadose zone, which consists of interlayered basalt lava flows and sedimentary interbeds, brine has moved up to 110 m laterally. This lateral migration suggests formation of perched water and horizontal transport during periods of high recharge. In a few locations, brine migrated to depths of 67 m within 3 to 5 yr. Elevated Cl– concentrations were found to depths of 2 m in roadbed material. In drainage ditches along roads, where runoff accumulates and recharge of surface water is high, Cl– was flushed from the sediments in 3 to 4 yr. In areas of lower recharge, Cl– remained in the sediments after 5 yr. Vertical brine movement is directly related to surface recharge through sediments. The distribution of Cl– in pore water and sediments is consistent with estimates of vadose zone residence times and spatial distribution of surface water recharge from other investigations at the subsurface disposal area.

  17. Subsurface geology of Kansai International Airport: sequence related to global glacial - interglacial cycles and island tectonics

    NASA Astrophysics Data System (ADS)

    Takemura, K.; Kitada, N.; Furudoi, T.; Nakaseko, K.

    2007-12-01

    Tectonic sedimentary basins aligned in the central part of Japan during Quaternary . Thick sediments deposited in these basins provide useful records of climatic changes and tectonics throughout Quaternary. The Osaka sedimentary basin including Osaka Bay and area of Kansai International Airport is one of them. The Quaternary Osaka sedimentary basin has developed at an eastern contractional bend of a major transcurrent fault system named the Median Tectonic Line, which divides the southwest Japan arc. The thickness of Pliocene - Pleistocene sediments reaches to ca 3500m at the deepest part. These sequences are called the Osaka Group and are distributed in the Osaka Bay and exposed in the surrounding mountain areas. The Osaka Group is characterized by alternating sequences of marine and nonmarine strata. The subsurface sediments of Kansai International Airport (KIA) is composed mainly of Pliocene - Pleistocene sediments, which is characterized by alternating sequences of marine and nonmarine strata related to glacial - interglacial cycles. . The stratigraphy at KIA was established by micropaleontological, tephrochronological and magnetostratigraphical method. The sedimentary sequence at KIX is divided into two main units (Kukojima and Sennanoki Formations in ascending order) with the uncomformity within two units. Although thick marine clay units are mainly of the subsurface sequence, characteristics of coarser sediment units have an important role of moving of water during construction of the reclaimed land.

  18. On using rational enzyme redesign to improve enzyme-mediated microbial dehalogenation of recalcitrant substances in deep-subsurface environments

    SciTech Connect

    Ornstein, R.L.

    1993-06-01

    Heavily halogenated hydrocarbons are one of the most prevalent classes of man-made recalcitrant environmental contaminants and often make their way into subsurface environments. Biodegradation of heavily chlorinated compounds in the deep subsurface often occurs at extremely slow rates because native enzymes of indigenous microbes are unable to efficiently metabolize such synthetic substances. Cost-effective engineering solutions do not exist for dealing with disperse and recalcitrant pollutants in the deep subsurface (i.e., ground water, soils, and sediments). Timely biodegradation of heavily chlorinated compounds in the deep subsurface may be best accomplished by rational redesign of appropriate enzymes that enhance the ability of indigenous microbes to metabolize these substances. The isozyme family cytochromes P450 are catalytically very robust and are found in all aerobic life forms and may be active in may anaerobes as well. The author is attempting to demonstrate proof-of-principle rational enzyme redesign of cytochromes P450 to enhance biodehalogenation.

  19. Relationship between the adhesive properties of bacteria and their transport and colonization in the subsurface environment. Final technical report

    SciTech Connect

    Fletcher, M.

    1997-03-13

    The adhesion of bacteria to sediment particle or rock surfaces considerably effects their transport in subsurface environments. This research focuses on the macromolecular properties of bacteria that determine their adhesiveness and on the significance of adhesion in transport of subsurface bacteria. Specific objectives include (1) to obtain adhesion mutants of subsurface Pseudomonas species altered in surface adhesives; (2) to determine alterations in adhesives in selected mutants; (3) to evaluate the effect of adhesiveness on transport and long-term distribution and colonization of bacteria in porous media. Primary methods will be tranposon mutagenesis to generate adhesion mutants, biochemical analyses of cell surface polymers, and the use of laboratory columns containing subsurface materials to study the distribution and transport of bacteria along flow paths over time.

  20. Remediation of contaminated subsurface materials by a metal-reducing bacterium

    SciTech Connect

    Gorby, Y.A.; Amonette, J.E.; Fruchter, J.S.

    1994-11-01

    A biotic approach for remediating subsurface sediments and groundwater contaminated with carbon tetrachloride (CT) and chromium was evaluated. Cells of the Fe(iii)-reducing bacterium strain BrY were added to sealed, anoxic flasks containing Hanford groundwater, natural subsurface sediments, and either carbon tetrachloride, CT, or oxidized chromium, Cr(VI). With lactate as the electron donor, BrY transformed CT to chloroform (CF), which accumulated to about 1 0 % of the initial concentration of CT. The remainder of the CT was transformed to unidentified, nonvolatile compounds. Transformation of CT by BrY was an indirect process Cells reduced solid phase Fe(ill) to chemically reactive FE(II) that chemically transformed the chlorinated contaminant. Cr(VI), in contrast, was reduced by a direct enzymatic reaction in the presence or absence of Fe(III)-bearing sediments. These results demonstrate that Fe(ill)-reducing bacteria provide potential for transforming CT and for reducing CR(VI) to less toxic Cr(III). Technologies for stimulating indigenous populations of metal-reducing bacteria or for introducing specific metal-reducing bacteria to the subsurface are being investigated.

  1. Estimating sedimentation rates and sources in a partially urbanized catchment using caesium-137

    NASA Astrophysics Data System (ADS)

    Ormerod, L. M.

    1998-06-01

    While there has been increased interest in determining sedimentation rates and sources in agricultural and forested catchments in recent years, there have been few studies dealing with urbanized catchments. A study of sedimentation rates and sources within channel and floodplain deposits of a partially urbanized catchment has been undertaken using the 137Cs technique. Results for sedimentation rates showed no particular downstream pattern. This may be partially explained by underestimation of sedimentation rates at some sites by failure to sample the full 137Cs profile, floodplain erosion and deliberate removal of sediment. Evidence of lateral increases in net sedimentation rates with distance from the channel may be explained by increased floodplain erosion at sites closer to the channel and floodplain formation by lateral deposition. Potential sediment sources for the catchment were considered to be forest topsoil, subsurface material and sediments derived from urban areas, which were found to be predominantly subsurface material. Tracing techniques showed an increase in subsurface material for downstream sites, confirming expectations that subsurface material would increase in the downstream direction in response to the direct and indirect effects of urbanization.

  2. Subsurface imaging across the 2001 Spokane, Washington earthquake swarm

    NASA Astrophysics Data System (ADS)

    Finn, S.; Stephenson, W. J.; Wicks, C. W.; Pratt, T. L.; Odum, J. K.; Angster, S. J.

    2012-12-01

    We acquired 4 km of minivibe reflection seismic data in Spokane, Washington, to image subsurface deformation associated with the 2001 swarm of shallow (<2 km) earthquakes. These data were collected by USGS as part of ongoing earthquake hazards investigations in the area. In 2001 unexplained earthquake ground shaking as well as audible "booms" were reported over a span of six months (June to November) in the Emerson-Garfield and West Central neighborhoods of Spokane.; the area has since been seismically quiescent. Seismograph recordings of the earthquake swarm suggest shallow depths of hypocenters, yet the local subsurface geology is not well known. Although the source region of this swarm is poorly constrained within Spokane due to sparse seismic station coverage in the area at that time, recent InSAR data analysis has revealed a zone of surface deformation that may be related to the earthquake swarm. This surface deformation consists of an elliptical area about 3 km across that had as much as 15 mm of uplift during 2001. Preliminary processing of the two new seismic profiles provides the first subsurface images of the upper 500 m within the Spokane area across the inferred source region. One seismic profile through downtown Spokane shows a three-layer structure of Holocene valley fill and Quaternary Lake Missoula flood deposits underlain by Tertiary Columbia River basalts. We observe a Columbia River basalt bedrock high of 100 m located between seismic profiles and verified by geologic and aeromagnetic maps. The seismic data also image a paleochannel showing the migration of the Spokane River through time. An inflection within the Quaternary basin sediment reflections suggests uplift from faulting that is consistent with the sense of deformation observed in the InSAR data.

  3. Progression of methanogenic degradation of crude oil in the subsurface

    USGS Publications Warehouse

    Bekins, B.A.; Hostettler, F.D.; Herkelrath, W.N.; Delin, G.N.; Warren, E.; Essaid, H.I.

    2005-01-01

    Our results show that subsurface crude-oil degradation rates at a long-term research site were strongly influenced by small-scale variations in hydrologic conditions. The site is a shallow glacial outwash aquifer located near Bemidji in northern Minnesota that became contaminated when oil spilled from a broken pipeline in August 1979. In the study area, separate-phase oil forms a subsurface oil body extending from land surface to about 1 m (3.3 ft) below the 6-8-m (20-26 ft)-deep water table. Oil saturation in the sediments ranges from 10-20% in the vadose zone to 30-70% near the water table. At depths below 2 m (6.6 ft), degradation of the separate-phase crude oil occurs under methanogenic conditions. The sequence of methanogenic alkane degradation depletes the longer chain n-alkanes before the shorter chain n-alkanes, which is opposite to the better known aerobic sequence. The rates of degradation vary significantly with location in the subsurface. Oil-coated soils within 1.5 m (5 ft) of land surface have experienced little degradation where soil water saturation is less than 20%. Oil located 2-8 m (6.6-26 ft) below land surface in areas of higher recharge has been substantially degraded. The best explanation for the association between recharge and enhanced degradation seems to be increased downward transport of microbial growth nutrients to the oil body. This is supported by observations of greater microbial numbers at higher elevations in the oil body and significant decreases with depth in nutrient concentrations, especially phosphorus. Our results suggest that environmental effects may cause widely diverging degradation rates in the same spill, calling into question dating methods based on degradation state. Copyright ?? 2005. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

  4. Geomicrobial Processes and Biodiversity in the Deep Terrestrial Subsurface

    SciTech Connect

    Fredrickson, Jim K.; Balkwill, David L.

    2005-09-01

    The concept of a deep microbial biosphere has advanced over the past several decades from a hypothesis viewed with considerable skepticism to being widely accepted. Phylogenetically diverse prokaryotes have been cultured from or detected via characterization of directly-extracted nucleic acids from a wide range of deep terrestrial environments. Recent advances have linked the metabolic potential of these microorganisms, determined directly or inferred from phylogeny, to biogeochemical reactions determined via geochemical measurements and modeling. Buried organic matter or kerogen is an important source of energy for sustaining anaerobic heterotrophic microbial communities in deep sediments and sedimentary rock although rates of respiration are among the slowest rates measured on the planet. In contrast, Subsurface Lithoautotrophic Microbial Ecosystems based on H2 as the primary energy source appear to dominate in many crystalline rock environments. These photosynthesis-independent ecosystems remain an enigma due to the difficulty in accessing and characterizing appropriate samples. Deep mines and dedicated rock laboratories, however, may offer unprecedented opportunities for investigating subsurface microbial communities and their interactions with the geosphere.

  5. Microbial Metagenomics Reveals Climate-Relevant Subsurface Biogeochemical Processes.

    PubMed

    Long, Philip E; Williams, Kenneth H; Hubbard, Susan S; Banfield, Jillian F

    2016-08-01

    Microorganisms play key roles in terrestrial system processes, including the turnover of natural organic carbon, such as leaf litter and woody debris that accumulate in soils and subsurface sediments. What has emerged from a series of recent DNA sequencing-based studies is recognition of the enormous variety of little known and previously unknown microorganisms that mediate recycling of these vast stores of buried carbon in subsoil compartments of the terrestrial system. More importantly, the genome resolution achieved in these studies has enabled association of specific members of these microbial communities with carbon compound transformations and other linked biogeochemical processes-such as the nitrogen cycle-that can impact the quality of groundwater, surface water, and atmospheric trace gas concentrations. The emerging view also emphasizes the importance of organism interactions through exchange of metabolic byproducts (e.g., within the carbon, nitrogen, and sulfur cycles) and via symbioses since many novel organisms exhibit restricted metabolic capabilities and an associated extremely small cell size. New, genome-resolved information reshapes our view of subsurface microbial communities and provides critical new inputs for advanced reactive transport models. These inputs are needed for accurate prediction of feedbacks in watershed biogeochemical functioning and their influence on the climate via the fluxes of greenhouse gases, CO2, CH4, and N2O.

  6. Microbial Metagenomics Reveals Climate-Relevant Subsurface Biogeochemical Processes.

    PubMed

    Long, Philip E; Williams, Kenneth H; Hubbard, Susan S; Banfield, Jillian F

    2016-08-01

    Microorganisms play key roles in terrestrial system processes, including the turnover of natural organic carbon, such as leaf litter and woody debris that accumulate in soils and subsurface sediments. What has emerged from a series of recent DNA sequencing-based studies is recognition of the enormous variety of little known and previously unknown microorganisms that mediate recycling of these vast stores of buried carbon in subsoil compartments of the terrestrial system. More importantly, the genome resolution achieved in these studies has enabled association of specific members of these microbial communities with carbon compound transformations and other linked biogeochemical processes-such as the nitrogen cycle-that can impact the quality of groundwater, surface water, and atmospheric trace gas concentrations. The emerging view also emphasizes the importance of organism interactions through exchange of metabolic byproducts (e.g., within the carbon, nitrogen, and sulfur cycles) and via symbioses since many novel organisms exhibit restricted metabolic capabilities and an associated extremely small cell size. New, genome-resolved information reshapes our view of subsurface microbial communities and provides critical new inputs for advanced reactive transport models. These inputs are needed for accurate prediction of feedbacks in watershed biogeochemical functioning and their influence on the climate via the fluxes of greenhouse gases, CO2, CH4, and N2O. PMID:27156744

  7. Introduction: energy and the subsurface

    PubMed Central

    Viswanathan, Hari S.

    2016-01-01

    This theme issue covers topics at the forefront of scientific research on energy and the subsurface, ranging from carbon dioxide (CO2) sequestration to the recovery of unconventional shale oil and gas resources through hydraulic fracturing. As such, the goal of this theme issue is to have an impact on the scientific community, broadly, by providing a self-contained collection of articles contributing to and reviewing the state-of-the-art of the field. This collection of articles could be used, for example, to set the next generation of research directions, while also being useful as a self-study guide for those interested in entering the field. Review articles are included on the topics of hydraulic fracturing as a multiscale problem, numerical modelling of hydraulic fracture propagation, the role of computational sciences in the upstream oil and gas industry and chemohydrodynamic patterns in porous media. Complementing the reviews is a set of original research papers covering growth models for branched hydraulic crack systems, fluid-driven crack propagation in elastic matrices, elastic and inelastic deformation of fluid-saturated rock, reaction front propagation in fracture matrices, the effects of rock mineralogy and pore structure on stress-dependent permeability of shales, topographic viscous fingering and plume dynamics in porous media convection. This article is part of the themed issue ‘Energy and the subsurface’. PMID:27597784

  8. Subsurface Explosions in Granular Media

    NASA Astrophysics Data System (ADS)

    Lai, Shuyue; Houim, Ryan; Oran, Elaine

    2015-11-01

    Numerical simulations of coupled gas-granular flows are used to study properties of shock formation and propagation in media, such as sand or regolith on the moon, asteroids, or comets. The simulations were performed with a multidimensional fully compressible model, GRAF, which solves two sets of coupled Navier-Stokes equations, one for the gas and one for the granular medium. The specific case discussed here is for a subsurface explosion in a granular medium initiated by an equivalent of 200g of TNT in depths ranging from 0.1m to 3m. The background conditions of 100K, 10 Pa and loose initial particle volume fraction of 25% are consistent with an event on a comet. The initial blast creates a cavity as a granular shock expands outwards. Since the gas-phase shock propagates faster than the granular shock in loose, granular material, some gas and particles are ejected before the granular shock arrives. When the granular shock reaches the surface, a cap-like structure forms. This cap breaks and may fall back on the surface and in this process, relatively dense particle clusters form. At lower temperatures, the explosion timescales are increased and entrained particles are more densely packed.

  9. Solar subsurface flows from local helioseismology

    NASA Astrophysics Data System (ADS)

    Zhao, Junwei; Chen, Ruizhu

    2016-07-01

    In this article, we review recent progresses in subsurface flows obtained from two local helioseismology methods: time-distance helioseismology and ring-diagram analysis. We review results in the following four topics: flows beneath sunspots and active regions, supergranular subsurface flows, shallow meridional flow and its variations with solar cycles, and meridional circulation in the deep solar interior. Despite recent advancements in methodology, modeling, and observations, many questions are still to be answered and a few topics remain controversial. More efforts, especially in numerical modeling and accurate interpretation of acoustic wave travel-time measurements, are needed to improve the derivations of subsurface flows.

  10. Microbial community transitions across the deep sediment-basement interface

    NASA Astrophysics Data System (ADS)

    Labonté, J.; Lever, M. A.; Orcutt, B.

    2015-12-01

    Previous studies of microbial abundance and geochemistry in deep marine sediments indicate a stimulation of microbial activity near the sediment-basement interface; yet, the extent to which microbial communities in bottom sediments and underlying crustal habitats interact is unclear. We conducted tag pyrosequencing on DNA extracted from a spectrum of deep sediment-basement samples to try to identify patterns in microbial community shifts across sediment-basement interfaces, focusing on samples from the subsurface of the Juan de Fuca Ridge flank (IODP Expedition 327). Our results demonstrate that sediment and the basaltic crust harbor microbial communities that are phylogenetically connected, but the eveness is characteristic of the environment. We will discuss the microbial community transitions that occur horizontally along fluid flow pathways and vertically across the sediment basement interface, as well as the possible implications regarding the controls of microbial community composition along deep sediment-basement interfaces in hydrothermal systems. We will also highlight efforts to overcome sample contamination in crustal subsurface samples.

  11. Exploring Microbial Life in Oxic Sediments Underlying Oligotrophic Ocean Gyres

    NASA Astrophysics Data System (ADS)

    Ziebis, W.; Orcutt, B.; Wankel, S. D.; D'Hondt, S.; Szubin, R.; Kim, J. N.; Zengler, K.

    2015-12-01

    Oxygen, carbon and nutrient availability are defining parameters for microbial life. In contrast to organic-rich sediments of the continental margins, where high respiration rates lead to a depletion of O2 within a thin layer at the sediment surface, it was discovered that O2 penetrates several tens of meters into organic-poor sediments underlying oligotrophic ocean gyres. In addition, nitrate, another important oxidant, which usually disappears rapidly with depth in anoxic sediments, tends to accumulate above seawater concentrations in the oxic subsurface, reflecting the importance of nitrogen cycling processes, including both nitrification and denitrification. Two IODP drilling expeditions were vital for exploring the nature of the deep subsurface beneath oligotrophic ocean gyres, expedition 329 to the South Pacific Gyre (SPG) and expedition 336 to North Pond, located on the western flank of the Mid-Atlantic ridge beneath the North Atlantic Gyre. Within the ultra-oligotrophic SPG O2 penetrates the entire sediment column from the sediment-water interface to the underlying basement to depths of > 75 m. At North Pond, a topographic depression filled with sediment and surrounded by steep basaltic outcrops, O2 penetrates deeply into the sediment (~ 30 m) until it eventually becomes depleted. O2 also diffuses upward into the sediment from seawater circulating within the young crust underlying the sediment, resulting in a deep oxic layer several meters above the basalt. Despite low organic carbon contents microbial cells persist throughout the entire sediment column within the SPG (> 75 m) and at North Pond, albeit at low abundances. We explored the nature of the subsurface microbial communities by extracting intact cells from large volumes of sediment obtained from drill cores of the two expeditions. By using CARD-FiSH, amplicon (16s rRNA) and metagenome sequencing we shed light on the phylogenetic and functional diversity of the elusive communities residing in the

  12. In-Well Sediment Incubators to Evaluate Microbial Community Stability and Dynamics following Bioimmobilization of Uranium

    SciTech Connect

    Baldwin, Brett R.; Peacock, Aaron D.; Gan, M.; Resch, Charles T.; Arntzen, Evan V.; Smithgall, A. N.; Pfiffner, S.; Freifeld, Barry M.; White, D. C.; Long, Philip E.

    2009-09-23

    An in-situ incubation device (ISI) was developed in order to investigate the stability and dynamics of sediment associated microbial communities to prevailing subsurface oxidizing or reducing conditions. Here we describe the use of these devices at the Old Rifle Uranium Mill Tailings Remedial Action (UMTRA) site. During the 7 month deployment oxidized Rifle aquifer background sediments (RABS) were deployed in previously biostimulated wells under iron reducing conditions, cell densities of known iron reducing bacteria including Geobacteraceae increased significantly showing the microbial community response to local subsurface conditions. PLFA profiles of RABS following in situ deployment were strikingly similar to those of adjacent sediment cores suggesting ISI results could be extrapolated to the native material of the test plots. Results for ISI deployed reduced sediments showed only slight changes in community composition and pointed toward the ability of the ISIs to monitor microbial community stability and response to subsurface conditions.

  13. Deglacial Subsurface Temperature Change in the Tropical North Atlantic Linked to Atlantic Meridional Overturning Circulation Variability

    NASA Astrophysics Data System (ADS)

    Schmidt, M. W.; Chang, P.; Otto-Bliesner, B. L.

    2010-12-01

    Coupled ocean-atmosphere modeling experiments indicate that Atlantic meridional overturning circulation (AMOC) variability is tightly coupled to abrupt tropical North Atlantic (TNA) climate change through both atmospheric and oceanic processes (Zhang, 2007; Chang et al., 2008; and Chiang et al., 2008). While a slowdown of AMOC in these experiments results in an atmospheric-induced surface cooling in the entire TNA, the subsurface experiences an even larger warming due to rapid reorganizations of ocean circulation patterns (Wan et al., 2009). In addition, observational records of detrended 20th century ocean temperature and salinity variability show a strong anticorrelation between surface cooling and subsurface warming in the TNA over the past several decades, suggesting changing vertical temperature gradients in this region may be a distinct fingerprint of AMOC variability (Zhang 2007). In order to test the hypothesis that subsurface temperature change in the TNA is coupled to AMOC variability across abrupt climate events over the last deglacial, we reconstructed high-resolution Mg/Ca-temperature and δ18O records from both surface (G. ruber) and sub-thermocline dwelling (G. truncatulinoides, 350-500 m depth and G. crassaformis, 450-580 m) planktonic foraminifera in the southern Caribbean Sea sediment core VM12-107 (11.33oN, 66.63oW; 1079 m; 18 cm/kyr sedimentation rate). Sea surface temperatures indicate a gradual warming in the TNA starting at ~19 kyr BP with small cold reversals of ~1.5oC during Heinrich Event 1 (H1) and the Younger Dryas (YD). In contrast, last glacial maximum subsurface temperatures were as much as 2.5oC warmer than Late Holocene values and H1 and the YD are marked by the warmest subsurface temperatures characterized by abrupt temperature increases as large as 4-5oC. Furthermore, a comparison of our subsurface temperature record with the Bermuda Rise 231Pa/230Th proxy record of AMOC variability (McManus et al., 2004) indicates a strong

  14. SORPTION OF NONIONIC SURFACTANT OLIGOMERS TO SEDIMENT AND PCE DNAPL: EFFECTS ON PCE DISTRIBUTION BETWEEN WATER AND SEDIMENT. (R826650)

    EPA Science Inventory

    Introduction of surfactant mixtures to the subsurface for the purpose of
    surfactant-enhanced aquifer remediation requires consideration of the effects of
    surfactant sorption to sediment and nonaqueous phase liquids. These effects
    include alteration of the solubiliz...

  15. Watershed-Scale Fungal Community Characterization along a pH Gradient in a Subsurface Environment Cocontaminated with Uranium and Nitrate

    PubMed Central

    Jasrotia, Puja; Green, Stefan J.; Canion, Andy; Overholt, Will A.; Prakash, Om; Wafula, Denis; Hubbard, Daniela; Watson, David B.; Schadt, Christopher W.; Brooks, Scott C.

    2014-01-01

    The objective of this study was to characterize fungal communities in a subsurface environment cocontaminated with uranium and nitrate at the watershed scale and to determine the potential contribution of fungi to contaminant transformation (nitrate attenuation). The abundance, distribution, and diversity of fungi in subsurface groundwater samples were determined using quantitative and semiquantitative molecular techniques, including quantitative PCR of eukaryotic small-subunit rRNA genes and pyrosequencing of fungal internal transcribed spacer (ITS) regions. Potential bacterial and fungal denitrification was assessed in sediment-groundwater slurries amended with antimicrobial compounds and in fungal pure cultures isolated from the subsurface. Our results demonstrate that subsurface fungal communities are dominated by members of the phylum Ascomycota, and a pronounced shift in fungal community composition occurs across the groundwater pH gradient at the field site, with lower diversity observed under acidic (pH <4.5) conditions. Fungal isolates recovered from subsurface sediments, including cultures of the genus Coniochaeta, which were detected in abundance in pyrosequence libraries of site groundwater samples, were shown to reduce nitrate to nitrous oxide. Denitrifying fungal isolates recovered from the site were classified and found to be distributed broadly within the phylum Ascomycota and within a single genus of the Basidiomycota. Potential denitrification rate assays with sediment-groundwater slurries showed the potential for subsurface fungi to reduce nitrate to nitrous oxide under in situ acidic pH conditions. PMID:24389927

  16. Watershed scale fungal community characterization along a pH gradient in a subsurface environment co-contaminated with uranium and nitrate

    SciTech Connect

    Jasrotia, Puja; Green, Stefan; Canion, Andy; Overholt, Will; Prakash, Om; Wafula, Dennis; Hubbard, Daniela; Watson, David B; Schadt, Christopher Warren; Brooks, Scott C; Kostka,

    2014-01-01

    The objective of this study was to characterize fungal communities in a subsurface environment co-contaminated with uranium and nitrate at the watershed scale, and to determine the potential contribution of fungi to contaminant transformation (nitrate attenuation). The abundance, distribution and diversity of fungi in subsurface groundwater samples were determined using quantitative and semi-quantitative molecular techniques, including quantitative PCR of eukaryotic SSU rRNA genes and pyrosequencing of fungal internal transcribed spacer (ITS) regions. Potential bacterial and fungal denitrification was assessed in sediment-groundwater slurries amended with antimicrobial compounds and in fungal pure cultures isolated from subsurface. Our results demonstrate that subsurface fungal communities are dominated by members of the phylum Ascomycota, and a pronounced shift in fungal community composition occurs across the groundwater pH gradient at the field site, with lower diversity observed under acidic (pH < 4.5) conditions. Fungal isolates recovered from subsurface sediments were shown to reduce nitrate to nitrous oxide, including cultures of the genus Coniochaeta that were detected in abundance in pyrosequence libraries of site groundwater samples. Denitrifying fungal isolates recovered from the site were classified, and found to be distributed broadly within the phylum Ascomycota, and within a single genus within the Basidiomycota. Potential denitrification rate assays with sediment-groundwater slurries showed the potential for subsurface fungi to reduce nitrate to nitrous oxide under in situ acidic pH conditions.

  17. Watershed-scale fungal community characterization along a pH gradient in a subsurface environment cocontaminated with uranium and nitrate.

    PubMed

    Jasrotia, Puja; Green, Stefan J; Canion, Andy; Overholt, Will A; Prakash, Om; Wafula, Denis; Hubbard, Daniela; Watson, David B; Schadt, Christopher W; Brooks, Scott C; Kostka, Joel E

    2014-03-01

    The objective of this study was to characterize fungal communities in a subsurface environment cocontaminated with uranium and nitrate at the watershed scale and to determine the potential contribution of fungi to contaminant transformation (nitrate attenuation). The abundance, distribution, and diversity of fungi in subsurface groundwater samples were determined using quantitative and semiquantitative molecular techniques, including quantitative PCR of eukaryotic small-subunit rRNA genes and pyrosequencing of fungal internal transcribed spacer (ITS) regions. Potential bacterial and fungal denitrification was assessed in sediment-groundwater slurries amended with antimicrobial compounds and in fungal pure cultures isolated from the subsurface. Our results demonstrate that subsurface fungal communities are dominated by members of the phylum Ascomycota, and a pronounced shift in fungal community composition occurs across the groundwater pH gradient at the field site, with lower diversity observed under acidic (pH <4.5) conditions. Fungal isolates recovered from subsurface sediments, including cultures of the genus Coniochaeta, which were detected in abundance in pyrosequence libraries of site groundwater samples, were shown to reduce nitrate to nitrous oxide. Denitrifying fungal isolates recovered from the site were classified and found to be distributed broadly within the phylum Ascomycota and within a single genus of the Basidiomycota. Potential denitrification rate assays with sediment-groundwater slurries showed the potential for subsurface fungi to reduce nitrate to nitrous oxide under in situ acidic pH conditions.

  18. Re-assessment of ossicle frequency patterns in sediment cores: rate of sedimentation related to Acanthaster planci

    NASA Astrophysics Data System (ADS)

    Fabricius, Katharina E.; Fabricius, Frank H.

    1992-07-01

    Data on Acanthaster planci skeletal element distribution in reefal subsurface sediment cores of two reefs of the central Great Barrier Reef (Walbran et al. 1989 a, b) were shown to be readily interpretable after a timescaled evaluation of element frequencies. After re-scaling using 14C bulk sediment ages, high frequencies of elements were recognized in the top layers of John Brewer Reef sediment cores and attributed to the two recent A. planci population outbreaks. Beneath these top layers, the subsurface sediments contain consistently low element frequencies down to bulk-sediment ages of 7750±100 years BP. From Green Island, the maximum abundance of skeletal elements was found in the sediment layers of about 1900 to 2300 years BP in some cores, but patterns were too inconsistent and the number of cores too small to suggest former A. planci outbreaks from these data. A strong correlation was found between the frequency of A. planci elements and the rate of sedimentation per time unit in sediment cores of all sites. This correlation was attributed to increased erosion of coral reefs as a consequence of the activities of high-density populations of A. planci. We conclude that reef erosion, after intense predation of reef-constructing organisms, has to be considered when causes of deterioriation of reef growth or termination of a reef facies in the geological past are discussed.

  19. STRUCTURE AND FUNCTION OF SUBSURFACE MICROBIAL COMMUNITIES AFFECTING RADIONUCLIDE TRANSPORT AND BIOIMMOBILIZATION

    SciTech Connect

    Joel E. Kostka; Lee Kerkhof; Kuk-Jeong Chin; Martin Keller; Joseph W. Stucki

    2011-06-15

    The objectives of this project were to: (1) isolate and characterize novel anaerobic prokaryotes from subsurface environments exposed to high levels of mixed contaminants (U(VI), nitrate, sulfate), (2) elucidate the diversity and distribution of metabolically active metal- and nitrate-reducing prokaryotes in subsurface sediments, and (3) determine the biotic and abiotic mechanisms linking electron transport processes (nitrate, Fe(III), and sulfate reduction) to radionuclide reduction and immobilization. Mechanisms of electron transport and U(VI) transformation were examined under near in situ conditions in sediment microcosms and in field investigations at the Oak Ridge Field Research Center (ORFRC), in Oak Ridge, Tennessee, where the subsurface is exposed to mixed contamination predominated by uranium and nitrate. A total of 20 publications (16 published or 'in press' and 4 in review), 10 invited talks, and 43 contributed seminars/ meeting presentations were completed during the past four years of the project. PI Kostka served on one proposal review panel each year for the U.S. DOE Office of Science during the four year project period. The PI leveraged funds from the state of Florida to purchase new instrumentation that aided the project. Support was also leveraged by the PI from the Joint Genome Institute in the form of two successful proposals for genome sequencing. Draft genomes are now available for two novel species isolated during our studies and 5 more genomes are in the pipeline. We effectively addressed each of the three project objectives and research highlights are provided. Task I - Isolation and characterization of novel anaerobes: (1) A wide range of pure cultures of metal-reducing bacteria, sulfate-reducing bacteria, and denitrifying bacteria (32 strains) were isolated from subsurface sediments of the Oak Ridge Field Research Center (ORFRC), where the subsurface is exposed to mixed contamination of uranium and nitrate. These isolates which are new

  20. Plutonium and americium in anoxic marine sediments: Evidence against remobitization

    NASA Astrophysics Data System (ADS)

    Carpenter, R.; Beasley, T. M.

    1981-10-01

    239 + 240Pu activities of 100-450dpm/kg are found down to 15-18 cm in anoxic Saanich Inlet sediments, with a subsurface maximum in undisturbed deposits. Integrated 239 + 240Pu inventories which overlap delivery estimates are present both in two cores of anoxic sediments from Saanich Inlet and in one core of oxic sediments 65 km away in Dabob Bay, Washington. 241Am /239 + 240Pu ratios in Saanich Inlet sediments overlap ratios in unfractionated midnorthern latitude fallout, in oxic sediments from the Washington continental shelf, and in anoxic sediments from two basins off southern California and Mexico. The 239 + 240Pu /137Cs ratios in three intervals of Saanich Inlet sediments are also in agreement with ratios previously reported for oxic coastal marine sediments. The Pu inventories, the Am/Pu and Pu/Cs ratios, and the Saanich Inlet Dabob Bay comparison all argue that Pu is not rapidly remobilized in anoxic sediments. The subsurface 239 + 240Pu activity maximum is not in agreement with the historical record of peak Pu fallout in 1963-1964 unless our 210Pb-derived sedimentation rates are incorrectly high. However, they are in good agreement with previous 210Pb and varve chronologies in Saanich Inlet, and also give reasonable dates for times when 239 + 240Pu and SNAP-9A supplied 238Pu first appear in the sediments. We conclude they properly date the maximum in sedimentary 239 + 240Pu activity at 1970-1973, and seek explanations for the 7-10yr time lag after peak fallout. 239 + 240Pu inventories in one core from the eastern basin of the Cariaco Trench and in two cores from Golfo Dulce. an anoxic basin off the Pacific coast of Costa Rica, are also in reasonable agreement with fallout delivery to these latitudes when excess 210Pb inventories and fluxes are used to verify recovery of at least a major fraction of the most recently deposited sediments.

  1. Component-Based Framework for Subsurface Simulations

    SciTech Connect

    Palmer, Bruce J.; Fang, Yilin; Hammond, Glenn E.; Gurumoorthi, Vidhya

    2007-08-01

    Simulations in the subsurface environment represent a broad range of phenomena covering an equally broad range of scales. Developing modelling capabilities that can integrate models representing different phenomena acting at different scales present formidable challenges both from the algorithmic and computer science perspective. This paper will describe the development of an integrated framework that will be used to combine different models into a single simulation. Initial work has focused on creating two frameworks, one for performing smooth particle hydrodynamics (SPH) simulations of fluid systems, the other for performing grid-based continuum simulations of reactive subsurface flow. The SPH framework is based on a parallel code developed for doing pore scale simulations, the continuum grid-based framework is based on the STOMP (Subsurface Transport Over Multiple Phases) code developed at PNNL. Future work will focus on combining the frameworks together to perform multiscale, multiphysics simulations of reactive subsurface flow.

  2. Complete Subsurface Elemental Composition Measurements with PING

    NASA Astrophysics Data System (ADS)

    Parsons, A. M.

    2012-06-01

    The Probing In situ with Neutrons and Gamma rays (PING) instrument will measure the complete bulk elemental composition of the subsurface of Mars down to ~ 1 m depth without the need for contacting the surface or extracting samples.

  3. SUBSURFACE REPOSITORY INTEGRATED CONTROL SYSTEM DESIGN

    SciTech Connect

    D.C. Randle

    2000-01-07

    The primary purpose of this document is to develop a preliminary high-level functional and physical control system architecture for the potential repository at Yucca Mountain. This document outlines an overall control system concept that encompasses and integrates the many diverse process and communication systems being developed for the subsurface repository design. This document presents integrated design concepts for monitoring and controlling the diverse set of subsurface operations. The Subsurface Repository Integrated Control System design will be composed of a series of diverse process systems and communication networks. The subsurface repository design contains many systems related to instrumentation and control (I&C) for both repository development and waste emplacement operations. These systems include waste emplacement, waste retrieval, ventilation, radiological and air monitoring, rail transportation, construction development, utility systems (electrical, lighting, water, compressed air, etc.), fire protection, backfill emplacement, and performance confirmation. Each of these systems involves some level of I&C and will typically be integrated over a data communications network throughout the subsurface facility. The subsurface I&C systems will also interface with multiple surface-based systems such as site operations, rail transportation, security and safeguards, and electrical/piped utilities. In addition to the I&C systems, the subsurface repository design also contains systems related to voice and video communications. The components for each of these systems will be distributed and linked over voice and video communication networks throughout the subsurface facility. The scope and primary objectives of this design analysis are to: (1) Identify preliminary system-level functions and interfaces (Section 6.2). (2) Examine the overall system complexity and determine how and on what levels the engineered process systems will be monitored, controlled, and

  4. DOE UST interim subsurface barrier technologies workshop

    SciTech Connect

    1992-09-01

    This document contains information which was presented at a workshop regarding interim subsurface barrier technologies that could be used for underground storage tanks, particularly the tank 241-C-106 at the Hanford Reservation.

  5. MODELING CONTAMINANT TRANSPORT THROUGH SUBSURFACE SYSTEMS

    EPA Science Inventory

    Modeling of contaminant transport through soil to groundwater to a receptor requires that consideration be given to the many processes which control the transport and fate of chemical constituents in the subsurface environment. These processes include volatilization, degradation,...

  6. Modeling the influence of subsurface topography on spatial and temporal variability of subsurface stormflow

    NASA Astrophysics Data System (ADS)

    van Verseveld, W. J.; Tromp-van Meerveld, H. J.; Weiler, M.; McDonnell, J. J.

    2003-12-01

    Recent investigations of spatial patterns of soil depth, water table and subsurface flow response at the hillslope scale suggest that the variability in depth to bedrock (or to any other low permeable layer) may be a primary control on the space-time variability of subsurface stormflow. However, simulating or even predicting subsurface flow variability is still a challenge. Even more problematic is the fact that spatially explicit soil depth information is generally lacking at hillslope and catchment scales. We investigate how soil depth variability affects the spatial and temporal response of subsurface stormflow and propose a new way forward to defining these controls on sites without soil depth data. We used long-term data of spatially explicit subsurface flow measurements from a trenched hillslope at the Panola Mountain Research Watershed, as well as soil depth and soil property information, to calibrate and verify the HillVi hillslope model. Then we generated numerous realizations of the subsurface topography using geo-statistical information of the observed soil depth in the watershed. Subsurface flow variability was simulated based on these subsurface topography realizations. The spatial-temporal properties of the modeled flow were compared with the spatial and temporal variability of the observed flow. HillVi is a quasi 3D spatially explicit saturated and unsaturated water balance model and is well suited for this approach as it captures all major subsurface runoff generation processes (matrix and macropore flow and infiltration, lateral subsurface flow and pipe flow). We discuss the potentials and drawbacks of this approach to simulate spatially variable outflow from hillslopes and the general role of subsurface topography on the spatial and temporal patterns of subsurface flow.

  7. Microbial life in the deep terrestrial subsurface

    SciTech Connect

    Fliermans, C.B.; Balkwill, D.L.; Beeman, R.E.

    1988-12-31

    The distribution and function of microorganisms is a vital issue in microbial ecology. The US Department of Energy`s Program, ``Microbiology of the Deep Subsurface,`` concentrates on establishing fundamental scientific information about organisms at depth, and the use of these organisms for remediation of contaminants in deep vadose zone and groundwater environments. This investigation effectively extends the Biosphere hundreds of meters into the Geosphere and has implications to a variety of subsurface activities.

  8. Floating insulated conductors for heating subsurface formations

    DOEpatents

    Burns, David; Goodwin, Charles R.

    2014-07-29

    A heating system for a subsurface formation includes a conduit located in a first opening in the subsurface formation. Three electrical conductors are located in the conduit. A return conductor is located inside the conduit. The return conductor is electrically coupled to the ends of the electrical conductors distal from the surface of the formation. Insulation is located inside the conduit. The insulation electrically insulates the three electrical conductors, the return conductor, and the conduit from each other.

  9. Phylogenetic relationships among subsurface microorganisms

    SciTech Connect

    Nierzwicki-Bauer, S.A.

    1991-01-01

    This report summarizes the progress made from 6/90--3/91 toward completion of our project, Phylogenetic Relationships among subsurface microorganisms. 16S rRNA was sequenced, and based on the sequence the SMCC isolates were assigned to preliminary groups. Microorganisms were obtained at various depths at the Savannah River Site, including the Surface (0 m), Congaree (91 m), and Middendorf (244 m, 259 m, 265 m). Sequence data from four isolates from the Congaree formation indicate these microorganisms can be divided into Pseudomonas spp. or Acinetobacter spp. Three 16S rRNA probes were synthesized based on sequence data. The synthesized probes were tested through in situ hybridization. Optimal conditions for in situ hybridization were determined. Because stability of RNA-DNA hybrids is dependent on hybridization stringency, related organisms can be differentiated using a single probe under different strigencies. The results of these hybridizations agree with results obtained by Balkwill and Reeves using restriction fragment length polymorphism analysis. The RNA content of a cell reflects its metabolic state. Cells which are starved for four days are not detectable with the homologous 16S rRNA probe. However, within 15 minutes of refeeding, detectable rRNA appeared. This suggests that organisms which are undetectable in environmental samples due to starvation may be detectable after addition of nutrients. Stepwise addition of specific nutrients could indicate which nutrients are rate limiting for growth. Preliminary experiments with soil samples from the Hanford Site indicate indigenous microorganisms can be detected by oligionucleotide probes. Further, using multiple probes based on universal sequences increases the number of organisms detected. Double label experiments, using a rhodamine-labelled oligionucleotide probe with free coumarin succinimidyl ester will allow simultaneous detection of total bacteria and specific 16S rRNA containing bacteria. 4 tabs. (MHB)

  10. Energy Requirements of Hydrogen-utilizing Microbes: A Boundary Condition for Subsurface Life

    NASA Technical Reports Server (NTRS)

    Hoehler, Tori M.; Alperin, Marc J.; Albert, Daniel B.; Martens, Christopher S.

    2003-01-01

    Microbial ecosystems based on the energy supplied by water-rock chemistry carry particular significance in the context of geo- and astrobiology. With no direct dependence on solar energy, lithotrophic microbes could conceivably penetrate a planetary crust to a depth limited only by temperature or pressure constraints (several kilometers or more). The deep lithospheric habitat is thereby potentially much greater in volume than its surface counterpart, and in addition offers a stable refuge against inhospitable surface conditions related to climatic or atmospheric evolution (e.g., Mars) or even high-energy impacts (e.g., early in Earth's history). The possibilities for a deep microbial biosphere are, however, greatly constrained by life s need to obtain energy at a certain minimum rate (the maintenance energy requirement) and of a certain minimum magnitude (the energy quantum requirement). The mere existence of these requirements implies that a significant fraction of the chemical free energy available in the subsurface environment cannot be exploited by life. Similar limits may also apply to the usefulness of light energy at very low intensities or long wavelengths. Quantification of these minimum energy requirements in terrestrial microbial ecosystems will help to establish a criterion of energetic habitability that can significantly constrain the prospects for life in Earth's subsurface, or on other bodies in the solar system. Our early work has focused on quantifying the biological energy quantum requirement for methanogenic archaea, as representatives of a plausible subsurface metabolism, in anoxic sediments (where energy availability is among the most limiting factors in microbial population growth). In both field and laboratory experiments utilizing these sediments, methanogens retain a remarkably consistent free energy intake, in the face of fluctuating environmental conditions that affect energy availability. The energy yields apparently required by

  11. Biogeochemical Cycle of Methanol in Anoxic Deep-Sea Sediments

    PubMed Central

    Yanagawa, Katsunori; Tani, Atsushi; Yamamoto, Naoya; Hachikubo, Akihiro; Kano, Akihiro; Matsumoto, Ryo; Suzuki, Yohey

    2016-01-01

    The biological flux and lifetime of methanol in anoxic marine sediments are largely unknown. We herein reported, for the first time, quantitative methanol removal rates in subsurface sediments. Anaerobic incubation experiments with radiotracers showed high rates of microbial methanol consumption. Notably, methanol oxidation to CO2 surpassed methanol assimilation and methanogenesis from CO2/H2 and methanol. Nevertheless, a significant decrease in methanol was not observed after the incubation, and this was attributed to the microbial production of methanol in parallel with its consumption. These results suggest that microbial reactions play an important role in the sources and sinks of methanol in subseafloor sediments. PMID:27301420

  12. Quantifying the dominant sources of sediment in a drained lowland agricultural catchment: The application of a thorium-based particle size correction in sediment fingerprinting

    NASA Astrophysics Data System (ADS)

    Foucher, Anthony; Laceby, Patrick J.; Salvador-Blanes, Sébastien; Evrard, Olivier; Le Gall, Marion; Lefèvre, Irène; Cerdan, Olivier; Rajkumar, Vignesh; Desmet, Marc

    2015-12-01

    Soil erosion is one of the main factors influencing land degradation and water quality at the global scale. Identifying the main sediment sources is therefore essential for the implementation of appropriate soil erosion mitigation measures. Accordingly, caesium-137 (137Cs) concentrations were used to determine the relative contribution of surface and subsurface erosion sources in a lowland drained catchment in France. As 137Cs concentrations are often dependent on particle size, specific surface area (SSA) and novel thorium (Th) based particle size corrections were applied. Surface and subsurface samples were collected to characterize the radionuclide properties of potential sources. Sediment samples were collected during one hydrological year and a sediment core was sampled to represent sediment accumulated over a longer temporal period. Additionally, sediment from tile drains was sampled to determine the radionuclide properties of sediment exported from the drainage network. A distribution modelling approach was used to quantify the relative sediment contributions from surface and subsurface sources. The results highlight a substantial enrichment in fine particles and associated 137Cs concentrations between the sources and the sediment. The application of both correction factors reduced this difference, with the Th correction providing a more accurate comparison of source and sediment samples than the SSA correction. Modelling results clearly indicate the dominance of surface sources during the flood events and in the sediment core. Sediment exported from the drainage network was modelled to originate predominantly from surface sources. This study demonstrates the potential of Th to correct for 137Cs particle size enrichment. More importantly, this research indicates that drainage networks may significantly increase the connectivity of surface sources to stream networks. Managing sediment transferred through drainage networks may reduce the deleterious effects of

  13. Determining the Hydraulic Conductivity of the Subsurface in Wetland Environments

    NASA Astrophysics Data System (ADS)

    Berry, L. E.; Mutiti, S.; Hazzard, S.

    2011-12-01

    Slug tests are a popular method for determining hydraulic conductivity (K) of subsurface material and have the potential to be very accurate because of minimal disturbance to the subsurface. A variety of methods and piezometer construction are widely used for slug tests. Most wetland environments are composed of low K material such as silt or clay, which can make determination of hydrogeologic properties challenging. This study is part of a broader ongoing project to understand the functions of wetlands in Milledgeville, Georgia, a city in the Oconee River Basin (ORB), which straddles the Piedmont and the Coastal Plain. The ORB sits on saprolite and gneiss bedrock, and consequently, its wetlands exhibit a high concentration of clay materials. One site, the Oconee River Greenway, lies along the riverbanks of the Oconee. The second site, Andalusia Farm, is a historical site formerly belonging to writer, Flannery O'Connor. The objective of this study was to determine the best method and/or piezometer type for determining K values for low permeability wetland material. We also investigated the potential of using heat and pressure monitoring to determine horizontal and vertical extent of slug tests. The Greenway wetland has significant seasonal interflow through a relatively more permeable sandy layer. Borehole logs and electrical resistivity profiling were used to study the subsurface stratigraphy. Slug test results from different types of piezometers (borehole, drive point, partially screened and fully screened) were compared. Pressure transducers and HOBO thermisters were used to collect water depth, pressure and temperature data. These results were also compared to results from sediment analyses, in-situ permeameters and heat monitoring. Drive point and borehole piezometers with equal diameters produced comparable K estimates at each site. However, fully screened piezometers of either installation type produced higher K values than partially screened piezometers

  14. Subsurface structure around Omi basin using borehole database

    NASA Astrophysics Data System (ADS)

    Kitada, N.; Ito, H.; Takemura, K.; Mitamura, M.

    2015-12-01

    Kansai Geo-informatics Network (KG-NET) is organized as a new system of management of GI-base in 2005. This organization collects the geotechnical and geological information of borehole data more than 60,000 data. GI-base is the database system of the KG-NET and platform to use these borehole data. Kansai Geo-informatics Research Committee (KG-R) is tried to explain the geotechnical properties and geological environment using borehole database in Kansai area. In 2014, KG-R established the 'Shin-Kansai Jiban Omi plain', and explain the subsurface geology and characteristics of geotechnical properties. In this study we introduce this result and consider the sedimental environment and characteristics in this area. Omi Basin is located in the central part of Shiga Prefecture which includes the largest lake in Japan called Lake Biwa. About 15,000 borehole data are corrected to consider the subsurface properties. The outline of topographical and geological characteristics of the basin is divided into west side and east side. The west side area is typical reverse fault called Biwako-Seigan fault zone along the lakefront. From Biwako-Seigan fault, the Omi basin is tilting down from east to west. Otherwise, the east areas distribute lowland and hilly area comparatively. The sedimentary facies are also complicate and difficult to be generally evaluated. So the discussion has been focused about mainly the eastern and western part of Lake Biwa. The widely dispersed volcanic ash named Aira-Tn (AT) deposited before 26,000-29,000 years ago (Machida and Arai, 2003), is sometimes interbedded the humic layers in the low level ground area. However, because most of the sediments are comprised by thick sand and gravels whose deposit age could not be investigated, it is difficult to widely identify the boundary of strata. Three types of basement rocks are distributed mainly (granite, sediment rock, rhyolite), and characteristics of deposit are difference of each backland basement rock

  15. Heterotrophic potential of Atribacteria from deep marine Antarctic sediment

    NASA Astrophysics Data System (ADS)

    Carr, S. A.; Orcutt, B.; Mandernack, K. W.; Spear, J. R.

    2015-12-01

    Bacteria belonging to the newly classified candidate phylum "Atribacteria" (formerly referred to as "OP9" and "JS1") are common in anoxic methane-rich sediments. However, the metabolic functions and biogeochemical role of these microorganisms in the subsurface remains unrealized due to the lack of pure culture representatives. This study observed a steady increase of Atribacteria-related sequences with increasing sediment depth throughout the methane-rich zone of the Adélie Basin, Antarctica (according to a 16S rRNA gene survey). To explore the functional potential of Atribacteria in this basin, samples from various depths (14, 25 and 97 meters below seafloor), were subjected to metagenomic sequencing. Additionally, individual cells were separated from frozen, unpreserved sediment for whole genome amplification. The successful isolation and sequencing of a single-amplified Atribacteria genome from these unpreserved sediments demonstrates a future use of single cell techniques with previously collected and frozen sediments. Our resulting single-cell amplified genome, combined with metagenomic interpretations, provides our first insights to the functional potential of Atribacteria in deep subsurface settings. As observed for non-marine Atribacteria, genomic analyses suggest a heterotrophic metabolism, with Atribacteria potentially producing fermentation products such as acetate, ethanol and CO2. These products may in turn support methanogens within the sediment microbial community and explain the frequent occurrence of Atribacteria in anoxic methane-rich sediments.

  16. Tillage impact on herbicide loss by surface runoff and lateral subsurface flow.

    PubMed

    Potter, Thomas L; Bosch, David D; Strickland, Timothy C

    2015-10-15

    There is worldwide interest in conservation tillage practices because they can reduce surface runoff, and agrichemical and sediment losses from farm fields. Since these practices typically increase infiltration, their use may increase subsurface transport of water-soluble contaminants. Thus, to assess long-term environmental benefits of conservation tillage data may be needed that quantify both surface and subsurface contaminant fluxes. This study focused on the herbicide fluometuron (N,N-dimethyl-N'-[3-(trifluoromethyl)phenyl]-urea) and its soil degradate DMF (N-methyl-N'-[3-(trifluoromethyl) phenyl]-urea). Both compounds are classed as "leachable". They were measured for 10 years in surface runoff and lateral subsurface flow from paired fields located on a hill slope in the Atlantic Coastal Plain region of the southeastern USA. One group of fields was conventionally tilled incorporating all crop residues into soil prior to planting. The second was strip tilled, a common conservation tillage practice. Seven fluometuron applications were made to cotton (Gossypium hirsutum) produced in rotation with peanut (Arachis hypogea). Combined fluometuron and DMF surface and subsurface losses from the conventionally tilled fields were equivalent to 1.2% and 0.13% of fluometuron applied and 0.31% and 0.32% from the strip tilled fields. Annual surface runoff losses were significantly greater from the conventionally tilled fields while the strip tilled fields had significantly greater annual subsurface losses. Results demonstrated that shifting from conventional to conservation tillage management of farm fields in this landscape will reduce surface runoff losses of herbicides like fluometuron but subsurface losses will likely increase. The same trends can be expected in landscapes with similar soil and hydrologic properties. This should be considered when planning implementation of programs that promote conservation tillage use.

  17. Sediment fingerprinting to determine the source of suspended sediment in a southern Piedmont stream.

    PubMed

    Mukundan, R; Radcliffe, D E; Ritchie, J C; Risse, L M; McKinley, R A

    2010-01-01

    Thousands of stream miles in the southern Piedmont region are impaired because of high levels of suspended sediment. It is unclear if the source is upland erosion from agricultural sources or bank erosion of historic sediment deposited in the flood plains between 1830 and 1930 when cotton farming was extensive. The objective of this study was to determine the source of high stream suspended sediment concentrations in a typical southern Piedmont watershed using sediment fingerprinting techniques. Twenty-one potential tracers were tested for their ability to discriminate between sources, conservative behavior, and lack of redundancy. Tracer concentrations were determined in potential sediment sources (forests, pastures, row crop fields, stream banks, and unpaved roads and construction sites), and suspended sediment samples collected from the stream and analyzed using mixing models. Results indicated that 137Cs and 15N were the best tracers to discriminate potential sediment sources in this watershed. The delta15N values showed distinct signatures in all the potential suspended sediment sources, and delta15N was a unique tracer to differentiate stream bank soil from upland subsurface soils, such as soil from construction sites, unpaved roads, ditches, and field gullies. Mixing models showed that about 60% of the stream suspended sediment originated from eroding stream banks, 23 to 30% from upland subsoil sources (e.g., construction sites and unpaved roads), and about 10 to 15% from pastures. The results may be applicable to other watersheds in the Piedmont depending on the extent of urbanization occurring in these watersheds. Better understanding of the sources of fine sediment has practical implications on the type of sediment control measures to be adopted. Investment of resources in improving water quality should consider the factors causing stream bank erosion and erosion from unpaved roads and construction sites to water quality impairment.

  18. The metal oxide fraction of pelagic sediment in the equatorial North Pacific Ocean: A source of metals in ferromanganese nodules

    USGS Publications Warehouse

    Piper, D.Z.

    1988-01-01

    Pelagic sediment recovered at DOMES Site A in the equatorial North Pacific (151??W, 9?? 15???N) consists of a surface homogeneous layer, approximately 10 cm thick, overlying a strongly mottled layer that is lighter in color. The radiolarian composition of both units is Quaternary. In areas where this sediment was only a few centimeters thick, the underlying sediment was early Tertiary. Clay mineralogy and major oxide composition of the two Quaternary sediments are uniform. Their similarity to continental shale suggests that the sediment has a terrigenous source. Clay mineralogy and major oxide composition of the Tertiary sediment also are uniform, although they differ markedly from the Quarternary sediment. In contrast to the major oxides, concentrations of Mn, Co, Cu, and Ni soluble in hydroxylamine hydrochlorideacetic acid are strongly different in the surface and subsurface Quaternary sediment. Mn and Ni exhibit pronounced depletions in the subsurface sediment, Ni slightly more than Mn. Cu is also depleted in the subsurface sediment, but less than Mn. It is also depleted in the subsurface Tertiary sediment, whereas the Mn concentration remains high. Concentration of Co relative to Mn increases into the subsurface Quaternary sediment to a constant Co:Mn ratio of 3 ?? 10-2. The trivalent REE (the REE exclusive of Ce) and Fe exhibit little down-core variation. Distribution of elements in these sediments is closely related to their concentration in associated surface ferromanganese nodules. The nodules are of two distinct types: those from the area where the Quaternary sediment is relatively thick have ??-MnO2 as the dominant manganese mineral. The ratios of Ni:Mn, Cu:Mn, and Fe:Mn in these nodules approximate the corresponding ratios of the soluble fraction of surface sediment. Todorokite is the dominant mineral of nodules recovered from areas where the Quaternary sediment is thin. Relatively high Cu/Mn, Ni/Mn, and low Fe/Mn ratios of these nodules mirror

  19. Examining Deep Subsurface Sulfate Reducing Bacterial Diversity to Test Spatial and Temporal Biogeography

    NASA Astrophysics Data System (ADS)

    Mills, H. J.; Reese, B. K.

    2013-12-01

    In this study, we take advantage of the isolation and scale of the deep marine subsurface to examine microbial biogeography. Unlike other environments, deep marine subsurface provides a unique opportunity to study biogeography across four dimensions. These samples are not only isolated by linear space on a global scale, but they are also temporally isolated by, in some cases, tens of millions of years. Through the support of multiple Integrated Ocean Drilling Program expeditions, we characterized the metabolically active fraction of the subsurface microbial community by targeting and sequencing 16S rRNA gene transcripts (RNA-based analysis). By characterizing the metabolically active fraction, we described lineages that were currently under selective environmental pressure and not relic lineages that may have become dormant or dead at some point in the past. This study was narrowed from the total diversity obtained to provide a detailed examination of the distribution and diversity of sulfate reducing bacteria (SRB); a functional group highly important to and ubiquitous in marine systems. The biogeochemical importance of this functional group, compounded with defined clades makes it a valuable and feasible target for a global biogeography study. SRB lineages from the deep subsurface were compared to contemporary lineages collected from multiple shallow sediment sites that had been extracted and sequenced using the same techniques. The SRB sequences acquired from our databases were clustered using 97% sequence similarity and analyzed using a suite of diversity and statistical tools. The geochemical conditions of the sediments sampled were considered when analyzing the resulting dendrograms and datasets. As hypothesized, lineages from the deep subsurface phylogenetically grouped together. However, similarities were detected to lineages from the shallow modern sediments, suggesting novel lineages may have evolved at a slow rate due to predicted lengthened life cycles

  20. Sediment chemoautotrophy in the coastal ocean

    NASA Astrophysics Data System (ADS)

    Vasquez-Cardenas, Diana; Meysman, Filip J. R.; van Breugel, Peter; Boschker, Henricus T. S.

    2016-04-01

    oxidation. Sediments with an O2-H2S interface exhibited highest chemoautotrophy activity in the top centimeter via canonical sulfur oxidation, whereas in the presence of electrogenic sulfur oxidation a uniform distribution of chemoautotrophy throughout the top centimeters of the sediment was evidenced. Lowest dark carbon fixation was found in permeable advective-driven sediments with deep oxygen penetration resulting in higher subsurface than surface activity. Hence, the depth-distribution of chemoautotrophy in coastal sediments varies due to several biogeochemical characteristics such as grain size, organic carbon content, presence of filamentous sulfur oxidizing bacteria, and macrofaunal activity.

  1. Sediment chemoautotrophy in the coastal ocean

    NASA Astrophysics Data System (ADS)

    Vasquez-Cardenas, Diana; Meysman, Filip J. R.; van Breugel, Peter; Boschker, Henricus T. S.

    2016-04-01

    sulfur oxidation. Sediments with an O2-H2S interface exhibited highest chemoautotrophy activity in the top centimeter via canonical sulfur oxidation, whereas in the presence of electrogenic sulfur oxidation a uniform distribution of chemoautotrophy throughout the top centimeters of the sediment was evidenced. Lowest dark carbon fixation was found in permeable advective-driven sediments with deep oxygen penetration resulting in higher subsurface than surface activity. Hence, the depth-distribution of chemoautotrophy in coastal sediments varies due to several biogeochemical characteristics such as grain size, organic carbon content, presence of filamentous sulfur oxidizing bacteria, and macrofaunal activity.

  2. Using Geochemical Indicators to Distinguish High Biogeochemical Activity in Sediments

    NASA Astrophysics Data System (ADS)

    Kenwell, A. M.; Navarre-Sitchler, A.; Prugue, R.; Spear, J. R.; Williams, K. H.; Maxwell, R. M.

    2014-12-01

    A better understanding of how microbial communities interact with their surroundings in physically and chemically heterogeneous subsurface environments will lead to improved quantification of biogeochemical reactions and associated nutrient cycling. This study develops a methodology to predict elevated rates of biogeochemical activity (microbial "hotspots") in subsurface environments by correlating microbial community structure with the spatial distribution of geochemical indicators in subsurface sediments. Statistical hierarchical cluster analyses (HCA) of X-ray fluorescence (XRF), simulated precipitation leachate, bioavailable Fe and Mn, total organic carbon (TOC), microbial community structure, grain size, bulk density and moisture content data were used to identify regions of the subsurface characterized by biogeochemical hotspots and sample characteristics indicative of these hotspots within fluvially-derived aquifer sediments. The methodology has been applied to (a) alluvial materials collected at a former uranium mill site near Rifle, Colorado and (b) relatively undisturbed floodplain deposits (soils and sediments) collected along the East River near Crested Butte, Colorado. At Rifle, 33 sediment samples were taken from 8 sediment cores and at the East River 33 soil/sediment samples were collected across and perpendicular to 3 active meanders. The East River watershed exhibits characteristic fluvial progression and serves as a representative example of many headwater catchments with the upper Colorado River basin. Initial clustering revealed that operationally defined hotspots were characterized by high organic carbon, bioavailable iron and dark colors but not necessarily low hydraulic conductivity. Applying the method to identify hotspots in both contaminated and natural floodplain deposits and their associated alluvial aquifers demonstrates the broad applicability of a geochemical indicator based approach.

  3. Subsurface Nitrogen-Cycling Microbial Communities at Uranium Contaminated Sites in the Colorado River Basin

    NASA Astrophysics Data System (ADS)

    Cardarelli, E.; Bargar, J.; Williams, K. H.; Dam, W. L.; Francis, C.

    2015-12-01

    Throughout the Colorado River Basin (CRB), uranium (U) persists as a relic contaminant of former ore processing activities. Elevated solid-phase U levels exist in fine-grained, naturally-reduced zone (NRZ) sediments intermittently found within the subsurface floodplain alluvium of the following Department of Energy-Legacy Management sites: Rifle, CO; Naturita, CO; and Grand Junction, CO. Coupled with groundwater fluctuations that alter the subsurface redox conditions, previous evidence from Rifle, CO suggests this resupply of U may be controlled by microbially-produced nitrite and nitrate. Nitrification, the two-step process of archaeal and bacterial ammonia-oxidation followed by bacterial nitrite oxidation, generates nitrate under oxic conditions. Our hypothesis is that when elevated groundwater levels recede and the subsurface system becomes anoxic, the nitrate diffuses into the reduced interiors of the NRZ and stimulates denitrification, the stepwise anaerobic reduction of nitrate/nitrite to dinitrogen gas. Denitrification may then be coupled to the oxidation of sediment-bound U(IV) forming mobile U(VI), allowing it to resupply U into local groundwater supplies. A key step in substantiating this hypothesis is to demonstrate the presence of nitrogen-cycling organisms in U-contaminated, NRZ sediments from the upper CRB. Here we investigate how the diversity and abundances of nitrifying and denitrifying microbial populations change throughout the NRZs of the subsurface by using functional gene markers for ammonia-oxidation (amoA, encoding the α-subunit of ammonia monooxygenase) and denitrification (nirK, nirS, encoding nitrite reductase). Microbial diversity has been assessed via clone libraries, while abundances have been determined through quantitative polymerase chain reaction (qPCR), elucidating how relative numbers of nitrifiers (amoA) and denitrifiers (nirK, nirS) vary with depth, vary with location, and relate to uranium release within NRZs in sediment

  4. SUBSURFACE REPOSITORY INTEGRATED CONTROL SYSTEM DESIGN

    SciTech Connect

    C.J. Fernado

    1998-09-17

    The purpose of this document is to develop preliminary high-level functional and physical control system architectures for the proposed subsurface repository at Yucca Mountain. This document outlines overall control system concepts that encompass and integrate the many diverse systems being considered for use within the subsurface repository. This document presents integrated design concepts for monitoring and controlling the diverse set of subsurface operations. The subsurface repository design will be composed of a series of diverse systems that will be integrated to accomplish a set of overall functions and objectives. The subsurface repository contains several Instrumentation and Control (I&C) related systems including: waste emplacement systems, ventilation systems, communication systems, radiation monitoring systems, rail transportation systems, ground control monitoring systems, utility monitoring systems (electrical, lighting, water, compressed air, etc.), fire detection and protection systems, retrieval systems, and performance confirmation systems. Each of these systems involve some level of I&C and will typically be integrated over a data communication network. The subsurface I&C systems will also integrate with multiple surface-based site-wide systems such as emergency response, health physics, security and safeguards, communications, utilities and others. The scope and primary objectives of this analysis are to: (1) Identify preliminary system level functions and interface needs (Presented in the functional diagrams in Section 7.2). (2) Examine the overall system complexity and determine how and on what levels these control systems will be controlled and integrated (Presented in Section 7.2). (3) Develop a preliminary subsurface facility-wide design for an overall control system architecture, and depict this design by a series of control system functional block diagrams (Presented in Section 7.2). (4) Develop a series of physical architectures that

  5. Effect of subsurface electrical heating and steam injection on the indigenous microbial community

    SciTech Connect

    Krauter, P.; MacQueen, D.; Horn, J.; Bishop, D.

    1995-11-01

    Since the potential for contaminant bioremediation in steam treated subsurface environments has not been explored, the thermal remedial treatment of a gasoline spill at Lawrence Livermore National Laboratory`s (LLNL) Livermore site provided an opportunity to study microbial community changes in the subsurface environment. Many terrestrial microorganisms die or become metabolically inactive if heated for a sufficient time at temperatures of 62-100{degrees}C thus thermal remediation techniques are expected to significantly alter the microbial community structure. We studied changes in community structure and population abundance as well as the characteristics of indigenous heat-tolerant microorganisms before and after steam treatment. Using fatty acid profiles from culturable microorganisms obtained from sediment cores before and after thermal treatment, a 90-98% decline in total microorganism populations in hot subsurface sediments (up to 94{degrees}C) was found. Surviving heat-tolerant microorganisms were found to possess elevated concentrations of saturated fatty acids in their lipid membranes. We also observed that some heat-tolerant microorganisms were capable of degrading gasoline compounds.

  6. Novel Archaea and Bacteria in a hydrologically isolated deep subsurface environment

    NASA Astrophysics Data System (ADS)

    Chandler, Darrell P.; Brockman, Fred J.; Fredrickson, James K.

    1997-07-01

    Total community DNA and RNA were extracted from a deep (188 m), saturated, mesophilic (17 degree(s)C), low biomass (10(superscript 4) cells g(superscript -1)) subsurface paleosol. 16S rDNA was amplified by PCR using universal eubacterial or archaeal primers and cloned. Cloned 16S rDNA fragments were sequenced and subjected to phylogenetic analysis. A novel clade of Crenarchaea were discovered which are most closely related to a single clone recovered from an Fe-S hot spring (80 degree(s)C). Novel Bacterial sequences were also found which branch deeply in the universal phylogenetic tree in association with Chloroflexus, Deinococcus, and Thermus. Total RNA analysis suggested that the novel Crenarchaea were active in this environment. Geological and hydrologic properties of the sediment indicate that microbial and nutrient transport between individual strata are restricted, and are consistent with chemolithoautotrophic metabolisms of cultured Crenarchaea involving the H(subscript 2)/SO(subscript 4) electron donor/acceptor couple. The physical properties of the surrounding lithologies suggest that these novel microorganisms are descendants of the microbial communities originally deposited with the sediment ca. 6 - 8 Mya. Identification of these novel, active microorganisms in an oligotrophic, hydrologically isolated subsurface system provides an opportunity and species-specific nucleic acid sequences and probes necessary to study long-term microbial survival in terrestrial subsurface environments.

  7. Finding Signals for Quiescence from the Dark Matter in Marine Subsurface Metagenomics

    NASA Astrophysics Data System (ADS)

    Biddle, J.; Marsh, A.; Rambo, I. M.; Pasqualone, A.; Christman, G.

    2014-12-01

    Microorganisms are expected to occupy deep marine sediments and underlying basalts, suriving on limited energy and potentially dividing on a thousand year time scale. For a microorganism to do this, and be only slightly active, is a difficult process to maintain, as many cells are programmed to be constantly active or face death. In order to maintain low levels of activity, cells may need additional control on which genes are activated in their genomes. In the surface world, particularly in eukaryotes, gene activity is controlled by factors including methylation of genes to silence activity. Methylation is now recognized as being present in many bacterial and archaeal genomes, and we hypothesized that this may be a prevalent lifestyle in subsurface organisms. We saw initial signals of methylation activity in a deep subsurface metatranscriptome and have shown which genes are methylated in a shallower sediment core. Methylation does appear to be a widespread phenomenon in microbial genomes of the subsurface, and additional tests will be needed to prove it's overall control on the potential for microbial activity.

  8. Subsurface photodisruption in scattering biological tissue

    NASA Astrophysics Data System (ADS)

    Sacks, Zachary S.; Spooner, Greg J. R.; Kurtz, Ron M.; Juhasz, Tibor; Mourou, Gerard A.

    2000-11-01

    Approximately five million people worldwide are blind due to complications from glaucoma. Current surgical techniques often fail due to infection and scarring. Both failure routes are associated with damaging surface tissues. Femtosecond lasers allow a method to create a highly precise incision beneath the surface of the tissue without damaging any of the overlying layers. However, subsurface surgery can only be performed where the beam can be focused tightly enough to cause optical breakdown. Under normal conditions, subsurface surgery is not possible since sclera is highly scattering. Using two independent methods, we show completely subsurface surgery in human sclera using a femtosecond laser. The first method is to make the sclera transparent by injecting a dehydrating agent. The second method is to choose a wavelength that is highly focusable in the sclera. Both methods may be applied in other tissues, such as skin. We show highly precise incisions in in vitro tissues. Subsurface femtosecond photodisruption may be useful for in vivo surgical technique to perform a completely subsurface surgery.

  9. Wave-Based Subsurface Guide Star

    SciTech Connect

    Lehman, S K

    2011-07-26

    Astronomical or optical guide stars are either natural or artificial point sources located above the Earth's atmosphere. When imaged from ground-based telescopes, they are distorted by atmospheric effects. Knowing the guide star is a point source, the atmospheric distortions may be estimated and, deconvolved or mitigated in subsequent imagery. Extending the guide star concept to wave-based measurement systems to include acoustic, seismo-acoustic, ultrasonic, and radar, a strong artificial scatterer (either acoustic or electromagnetic) may be buried or inserted, or a pre-existing or natural sub-surface point scatterer may be identified, imaged, and used as a guide star to determine properties of the sub-surface volume. That is, a data collection is performed on the guide star and the sub-surface environment reconstructed or imaged using an optimizer assuming the guide star is a point scatterer. The optimization parameters are the transceiver height and bulk sub-surface background refractive index. Once identified, the refractive index may be used in subsequent reconstructions of sub-surface measurements. The wave-base guide star description presented in this document is for a multimonostatic ground penetrating radar (GPR) but is applicable to acoustic, seismo-acoustic, and ultrasonic measurement systems operating in multimonostatic, multistatic, multibistatic, etc., modes.

  10. Subsurface Shielding Source Term Specification Calculation

    SciTech Connect

    S.Su

    2001-04-12

    The purpose of this calculation is to establish appropriate and defensible waste-package radiation source terms for use in repository subsurface shielding design. This calculation supports the shielding design for the waste emplacement and retrieval system, and subsurface facility system. The objective is to identify the limiting waste package and specify its associated source terms including source strengths and energy spectra. Consistent with the Technical Work Plan for Subsurface Design Section FY 01 Work Activities (CRWMS M&O 2001, p. 15), the scope of work includes the following: (1) Review source terms generated by the Waste Package Department (WPD) for various waste forms and waste package types, and compile them for shielding-specific applications. (2) Determine acceptable waste package specific source terms for use in subsurface shielding design, using a reasonable and defensible methodology that is not unduly conservative. This calculation is associated with the engineering and design activity for the waste emplacement and retrieval system, and subsurface facility system. The technical work plan for this calculation is provided in CRWMS M&O 2001. Development and performance of this calculation conforms to the procedure, AP-3.12Q, Calculations.

  11. Impact of abrupt deglacial climate change on tropical Atlantic subsurface temperatures.

    PubMed

    Schmidt, Matthew W; Chang, Ping; Hertzberg, Jennifer E; Them, Theodore R; Ji, Link; J, Link; Otto-Bliesner, Bette L

    2012-09-01

    Both instrumental data analyses and coupled ocean-atmosphere models indicate that Atlantic meridional overturning circulation (AMOC) variability is tightly linked to abrupt tropical North Atlantic (TNA) climate change through both atmospheric and oceanic processes. Although a slowdown of AMOC results in an atmospheric-induced surface cooling in the entire TNA, the subsurface experiences an even larger warming because of rapid reorganizations of ocean circulation patterns at intermediate water depths. Here, we reconstruct high-resolution temperature records using oxygen isotope values and Mg/Ca ratios in both surface- and subthermocline-dwelling planktonic foraminifera from a sediment core located in the TNA over the last 22 ky. Our results show significant changes in the vertical thermal gradient of the upper water column, with the warmest subsurface temperatures of the last deglacial transition corresponding to the onset of the Younger Dryas. Furthermore, we present new analyses of a climate model simulation forced with freshwater discharge into the North Atlantic under Last Glacial Maximum forcings and boundary conditions that reveal a maximum subsurface warming in the vicinity of the core site and a vertical thermal gradient change at the onset of AMOC weakening, consistent with the reconstructed record. Together, our proxy reconstructions and modeling results provide convincing evidence for a subsurface oceanic teleconnection linking high-latitude North Atlantic climate to the tropical Atlantic during periods of reduced AMOC across the last deglacial transition. PMID:22908256

  12. Impact of abrupt deglacial climate change on tropical Atlantic subsurface temperatures

    PubMed Central

    Schmidt, Matthew W.; Chang, Ping; Hertzberg, Jennifer E.; Them, Theodore R.; Ji, Link; Otto-Bliesner, Bette L.

    2012-01-01

    Both instrumental data analyses and coupled ocean-atmosphere models indicate that Atlantic meridional overturning circulation (AMOC) variability is tightly linked to abrupt tropical North Atlantic (TNA) climate change through both atmospheric and oceanic processes. Although a slowdown of AMOC results in an atmospheric-induced surface cooling in the entire TNA, the subsurface experiences an even larger warming because of rapid reorganizations of ocean circulation patterns at intermediate water depths. Here, we reconstruct high-resolution temperature records using oxygen isotope values and Mg/Ca ratios in both surface- and subthermocline-dwelling planktonic foraminifera from a sediment core located in the TNA over the last 22 ky. Our results show significant changes in the vertical thermal gradient of the upper water column, with the warmest subsurface temperatures of the last deglacial transition corresponding to the onset of the Younger Dryas. Furthermore, we present new analyses of a climate model simulation forced with freshwater discharge into the North Atlantic under Last Glacial Maximum forcings and boundary conditions that reveal a maximum subsurface warming in the vicinity of the core site and a vertical thermal gradient change at the onset of AMOC weakening, consistent with the reconstructed record. Together, our proxy reconstructions and modeling results provide convincing evidence for a subsurface oceanic teleconnection linking high-latitude North Atlantic climate to the tropical Atlantic during periods of reduced AMOC across the last deglacial transition. PMID:22908256

  13. Impact of abrupt deglacial climate change on tropical Atlantic subsurface temperatures.

    PubMed

    Schmidt, Matthew W; Chang, Ping; Hertzberg, Jennifer E; Them, Theodore R; Ji, Link; J, Link; Otto-Bliesner, Bette L

    2012-09-01

    Both instrumental data analyses and coupled ocean-atmosphere models indicate that Atlantic meridional overturning circulation (AMOC) variability is tightly linked to abrupt tropical North Atlantic (TNA) climate change through both atmospheric and oceanic processes. Although a slowdown of AMOC results in an atmospheric-induced surface cooling in the entire TNA, the subsurface experiences an even larger warming because of rapid reorganizations of ocean circulation patterns at intermediate water depths. Here, we reconstruct high-resolution temperature records using oxygen isotope values and Mg/Ca ratios in both surface- and subthermocline-dwelling planktonic foraminifera from a sediment core located in the TNA over the last 22 ky. Our results show significant changes in the vertical thermal gradient of the upper water column, with the warmest subsurface temperatures of the last deglacial transition corresponding to the onset of the Younger Dryas. Furthermore, we present new analyses of a climate model simulation forced with freshwater discharge into the North Atlantic under Last Glacial Maximum forcings and boundary conditions that reveal a maximum subsurface warming in the vicinity of the core site and a vertical thermal gradient change at the onset of AMOC weakening, consistent with the reconstructed record. Together, our proxy reconstructions and modeling results provide convincing evidence for a subsurface oceanic teleconnection linking high-latitude North Atlantic climate to the tropical Atlantic during periods of reduced AMOC across the last deglacial transition.

  14. Sediment mixing and accumulation rate effects on radionuclide depth profiles in Hudson estuary sediments

    SciTech Connect

    Olsen, C.R.; Simpson, H.J.; Peng, T.H.; Bopp, R.F.; Trier, R.M.

    1981-11-01

    Measured anthropogenic radionuclide profiles in sediment cores from the Hudson River estuary were compared with profiles computed by using known input histories of radionuclides to the estuary and mixing coefficients which decreased exponentially with depth in the sediment. Observed /sup 134/Cs sediment depth profiles were used in the mixing rate computation because reactor releases were the only significant source for this nuclide, whereas the inputs of /sup 137/Cs and /sup 239,240/Pu to the estuary were complicated by runoff or erosion in upstream areas, in addition to direct fallout from precipitation. Our estimates for the rates of surface sediment mixing in the low salinity reach of the estuary range from 0.25 to 1 cm/sup 2//yr, or less. In some areas of the harbor adjacent to New York City, where fine-particle accumulation rates are generally 3 cm/yr, and often as high as 10 to 20 cm/yr, sediment mixing rates as high as 10 cm/sup 2//yr would have little effect on radionuclide peak distributions. Consequently, anthropogenic radionuclide maximum activities in subsurface sediments of the Hudson appear to be useful as time-stratigraphic reference levels, which can be correlated with periods of maximum radionuclide inputs for estimating rates and patterns of sediment accumulation. 10 figures.

  15. Sediment mixing and accumulation rate effects on radionuclide depth profiles in Hudson estuary sediments

    SciTech Connect

    Olsen, C.R.; Simpson, H.J.; Peng, T.; Bopp, R.F.; Trier, R.M.

    1981-11-20

    Measured anthropogenic radionuclide profiles in sediment cores from the Hudson River estuary were compared with profiles computed by using known input histories of radionuclides to the estuary and mixing coefficients which decreased exponentially with depth in the sediment. Observed /sup 134/Cs sediment depth profiles were used in the mixing rate computation because reactor releases were the only significant source for this nuclide, whereas the inputs of /sup 137/Cs and /sup 239.240/Pu to the estuary were complicated by runoff or erosion in upstream areas, in addition to direct fallout from precipitation. Our estimates for the rates of surface sediment mixing in the low salinity reach of the estuary range from 0.25 to 1 cm/sup 2//yr, or less. In some areas of the harbor adjacent to New York City, were fine-particle accumulation rates are generally >3 cm/yr, and often as high as 10 to 20 cm/yr, sediment mixing rates as high as 10 cm/sup 2//yr would have little effect on radionuclide peak distributions. Consequently, anthropogenic radionuclide maximum activities in subsurface sediments of the Hudson appear to be useful as time-stratigraphic reference levels, which can be correlated with periods of maximum radionuclide inputs for estimating rates and patterns of sediment accumulation.

  16. Tidal response of Europa's subsurface ocean

    NASA Astrophysics Data System (ADS)

    Karatekin, Özgür; Comblen, Richard; Toubeau, Jonathan; Deleersnijder, Eric; van Hoolst, Tim; Dehant, Veronique

    2010-05-01

    Observations of Cassini and Galileo spacecrafts suggest the presence of subsurface global water oceans under the icy shells of several satellites of Jupiter and Saturn. Previous studies have shown that in the presence of subsurface oceans, time-variable tides cause large periodic surface displacements and that tidal dissipation in the icy shell becomes a major energy source that can affect long-term orbital evolution. However, in most studies so far, the dynamics of these satellite oceans have been neglected. In the present study, we investigate the tidal response of the subsurface ocean of Europa to a time-varying potential. Two-dimensional nonlinear shallow water equations are solved on a sphere by means of a finite element code. The resulting ocean tidal flow velocities and surface displacements will be presented.

  17. Complete Subsurface Elemental Composition Measurements With PING

    NASA Technical Reports Server (NTRS)

    Parsons, A. M.

    2012-01-01

    The Probing In situ with Neutrons and Gamma rays (PING) instrument will measure the complete bulk elemental composition of the subsurface of Mars as well as any other solid planetary body. PING can thus be a highly effective tool for both detailed local geochemistry science investigations and precision measurements of Mars subsurface reSOurces in preparation for future human exploration. As such, PING is thus fully capable of meeting a majority of both ncar and far term elements in Challenge #1 presented for this conference. Measuring the ncar subsurface composition of Mars will enable many of the MEPAG science goals and will be key to filling an important Strategic Knowledge Gap with regard to In situ Resources Utilization (ISRU) needs for human exploration. [1, 2] PING will thus fill an important niche in the Mars Exploration Program.

  18. Autonomous microexplosives subsurface tracing system final report.

    SciTech Connect

    Engler, Bruce Phillip; Nogan, John; Melof, Brian Matthew; Uhl, James Eugene; Dulleck, George R., Jr.; Ingram, Brian V.; Grubelich, Mark Charles; Rivas, Raul R.; Cooper, Paul W.; Warpinski, Norman Raymond; Kravitz, Stanley H.

    2004-04-01

    The objective of the autonomous micro-explosive subsurface tracing system is to image the location and geometry of hydraulically induced fractures in subsurface petroleum reservoirs. This system is based on the insertion of a swarm of autonomous micro-explosive packages during the fracturing process, with subsequent triggering of the energetic material to create an array of micro-seismic sources that can be detected and analyzed using existing seismic receiver arrays and analysis software. The project included investigations of energetic mixtures, triggering systems, package size and shape, and seismic output. Given the current absence of any technology capable of such high resolution mapping of subsurface structures, this technology has the potential for major impact on petroleum industry, which spends approximately $1 billion dollar per year on hydraulic fracturing operations in the United States alone.

  19. Improving the biodegradative capacity of subsurface bacteria

    SciTech Connect

    Romine, M.F.; Brockman, F.J.

    1993-04-01

    The continual release of large volumes of synthetic materials into the environment by agricultural and industrial sources over the last few decades has resulted in pollution of the subsurface environment. Cleanup has been difficult because of the relative inaccessibility of the contaminants caused by their wide dispersal in the deep subsurface, often at low concentrations and in large volumes. As a possible solution for these problems, interest in the introduction of biodegradative bacteria for in situ remediation of these sites has increased greatly in recent years (Timmis et al. 1988). Selection of biodegradative microbes to apply in such cleanup is limited to those strains that can survive among the native bacterial and predator community members at the particular pH, temperature, and moisture status of the site (Alexander, 1984). The use of microorganisms isolated from subsurface environments would be advantageous because the organisms are already adapted to the subsurface conditions. The options are further narrowed to strains that are able to degrade the contaminant rapidly, even in the presence of highly recalcitrant anthropogenic waste mixtures, and in conditions that do not require addition of further toxic compounds for the expression of the biodegradative capacity (Sayler et al. 1990). These obstacles can be overcome by placing the genes of well-characterized biodegradative enzymes under the control of promoters that can be regulated by inexpensive and nontoxic external factors and then moving the new genetic constructs into diverse groups of subsurface microbes. ne objective of this research is to test this hypothesis by comparing expression of two different toluene biodegradative enzymatic pathways from two different regulatable promoters in a variety of subsurface isolates.

  20. MSTS - Multiphase Subsurface Transport Simulator theory manual

    SciTech Connect

    White, M.D.; Nichols, W.E.

    1993-05-01

    The US Department of Energy, through the Yucca Mountain Site Characterization Project Office, has designated the Yucca Mountain site in Nevada for detailed study as the candidate US geologic repository for spent nuclear fuel and high-level radioactive waste. Site characterization will determine the suitability of the Yucca Mountain site for the potential waste repository. If the site is determined suitable, subsequent studies and characterization will be conducted to obtain authorization from the Nuclear Regulatory Commission to construct the potential waste repository. A principal component of the characterization and licensing processes involves numerically predicting the thermal and hydrologic response of the subsurface environment of the Yucca Mountain site to the potential repository over a 10,000-year period. The thermal and hydrologic response of the subsurface environment to the repository is anticipated to include complex processes of countercurrent vapor and liquid migration, multiple-phase heat transfer, multiple-phase transport, and geochemical reactions. Numerical simulators based on mathematical descriptions of these subsurface phenomena are required to make numerical predictions of the thermal and hydrologic response of the Yucca Mountain subsurface environment The engineering simulator called the Multiphase Subsurface Transport Simulator (MSTS) was developed at the request of the Yucca Mountain Site Characterization Project Office to produce numerical predictions of subsurface flow and transport phenomena at the potential Yucca Mountain site. This document delineates the design architecture and describes the specific computational algorithms that compose MSTS. Details for using MSTS and sample problems are given in the {open_quotes}User`s Guide and Reference{close_quotes} companion document.

  1. Apparatus for passive removal of subsurface contaminants

    DOEpatents

    Pemberton, Bradley E.; May, Christopher P.; Rossabi, Joseph

    1997-01-01

    An apparatus is provided which passively removes contaminated gases from a subsurface. The apparatus includes a riser pipe extending into a subsurface which has an exterior end in fluid communication with a valve. When well pressure is greater than atmospheric pressure, the valve opens to release contaminants into the atmosphere, and when well pressure is less than atmospheric pressure, the valve closes to prevent flow of air into the well. The valve assembly of the invention comprises a lightweight ball which is lifted from its valve seat with a slight pressure drop between the well and the atmosphere.

  2. Heating systems for heating subsurface formations

    SciTech Connect

    Nguyen, Scott Vinh; Vinegar, Harold J.

    2011-04-26

    Methods and systems for heating a subsurface formation are described herein. A heating system for a subsurface formation includes a sealed conduit positioned in an opening in the formation and a heat source. The sealed conduit includes a heat transfer fluid. The heat source provides heat to a portion of the sealed conduit to change phase of the heat transfer fluid from a liquid to a vapor. The vapor in the sealed conduit rises in the sealed conduit, condenses to transfer heat to the formation and returns to the conduit portion as a liquid.

  3. Subsurface Microbes Expanding the Tree of Life

    SciTech Connect

    Banfield, Jillian

    2015-05-11

    Jillian Banfield, Ph.D., UC Berkeley Professor and Berkeley Lab Earth Sciences Division staff scientist and long-time user of the DOE Joint Genome Institute’s resources shares her perspective on how the DOE JGI helps advance her research addressing knowledge gaps related to the roles of subsurface microbial communities in biogeochemical cycling. The video was filmed near the town of Rifle, Colorado at the primary field site for Phase I of the Subsurface Systems Scientific Focus Area 2.0 sponsored by the DOE Office of Biological and Environmental Research.

  4. Induction heaters used to heat subsurface formations

    DOEpatents

    Nguyen, Scott Vinh; Bass, Ronald M.

    2012-04-24

    A heating system for a subsurface formation includes an elongated electrical conductor located in the subsurface formation. The electrical conductor extends between at least a first electrical contact and a second electrical contact. A ferromagnetic conductor at least partially surrounds and at least partially extends lengthwise around the electrical conductor. The electrical conductor, when energized with time-varying electrical current, induces sufficient electrical current flow in the ferromagnetic conductor such that the ferromagnetic conductor resistively heats to a temperature of at least about 300.degree. C.

  5. Radar Soundings of the Subsurface of Mars

    NASA Technical Reports Server (NTRS)

    Picardi, Giovanni; Plaut, Jeffrey J.; Biccari, Daniela; Bombaci, Ornella; Calabrese, Diego; Cartacci, Marco; Cicchetti, Andrea; Clifford, Stephen M.; Edenhofer, Peter; Farrell, William M.; Federico, Costanzo; Frigeri, Alessandro; Gurnett, Donald A.; Hagfors, Tor; Heggy, Essam; Herique, Alain; Huff, Richard L.; Ivanov, Anton B.; Johnson, William T. K.; Jordan, Rolando L.; Kirchner, Donald L.; Kofman, Wlodek; Leuschen, Carlton J.; Nielsen, Erling; Orosei, Roberto

    2005-01-01

    The martian subsurface has been probed to kilometer depths by the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument aboard the Mars Express orbiter. Signals penetrate the polar layered deposits, probably imaging the base of the deposits. Data from the northern lowlands of Chryse Planitia have revealed a shallowly buried quasi-circular structure about 250 kilometers in diameter that is interpreted to be an impact basin. In addition, a planar reflector associated with the basin structure may indicate the presence of a low-loss deposit that is more than 1 kilometer thick.

  6. Apparatus for passive removal of subsurface contaminants

    DOEpatents

    Pemberton, B.E.; May, C.P.; Rossabi, J.

    1997-06-24

    An apparatus is provided which passively removes contaminated gases from a subsurface. The apparatus includes a riser pipe extending into a subsurface which has an exterior end in fluid communication with a valve. When well pressure is greater than atmospheric pressure, the valve opens to release contaminants into the atmosphere, and when well pressure is less than atmospheric pressure, the valve closes to prevent flow of air into the well. The valve assembly of the invention comprises a lightweight ball which is lifted from its valve seat with a slight pressure drop between the well and the atmosphere. 7 figs.

  7. Rain and channel flow supplements to subsurface water beneath hyper-arid ephemeral stream channels

    NASA Astrophysics Data System (ADS)

    Kampf, Stephanie K.; Faulconer, Joshua; Shaw, Jeremy R.; Sutfin, Nicholas A.; Cooper, David J.

    2016-05-01

    In hyper-arid regions, ephemeral stream channels are important sources of subsurface recharge and water supply for riparian vegetation, but few studies have documented the subsurface water content dynamics of these systems. This study examines ephemeral channels in the hyper-arid western Sonoran Desert, USA to determine how frequently water recharges the alluvial fill and identify variables that affect the depth and persistence of recharge. Precipitation, stream stage, and subsurface water content measurements were collected over a three-year study at six channels with varying contributing areas and thicknesses of alluvial fill. All channels contain coarse alluvium composed primarily of sands and gravels, and some locations also have localized layers of fine sediment at 2-3 m depth. Rain alone contributed 300-400 mm of water input to these channels over three years, but water content responses were only detected for 36% of the rain events at 10 cm depth, indicating that much of the rain water was either quickly evaporated or taken up by plants. Pulses of water from rain events were detected only in the top meter of alluvium. The sites each experienced ⩽5 brief flow events, which caused transient saturation that usually lasted only a few hours longer than flow. These events were the only apparent source of water to depths >1 m, and water from flow events quickly percolated past the deepest measurement depths (0.5-3 m). Sustained saturation in the shallow subsurface only developed where there was a near-surface layer of finer consolidated sediments that impeded deep percolation.

  8. Tropical North Atlantic Subsurface Temperature Change Linked to Atlantic Meridional Overturning Circulation Variability During the Last Deglacial

    NASA Astrophysics Data System (ADS)

    Schmidt, M. W.; Chang, P.

    2009-12-01

    Water hosing experiments using coupled ocean-atmosphere models indicate that Atlantic meridional overturning circulation (AMOC) variability can have a major impact on abrupt tropical North Atlantic (TNA) climate change through both atmospheric and oceanic processes (Zhang, 2007; Chang et al., 2008; Chiang et al., 2008). While a slowdown of AMOC results in an atmospheric-induced surface cooling in the entire TNA, the subsurface experiences an even larger warming due to rapid reorganizations of ocean circulation patterns (Wan et al., 2009). In addition, observed records of detrended 20th century ocean temperature and salinity variability show a strong anticorrelation between surface cooling and subsurface warming in the TNA over the past several decades, suggesting changing vertical temperature gradients in this region may be a distinct fingerprint of AMOC variability (Zhang 2007). In order to test the hypothesis that surface and subsurface temperature change in the TNA are sensitive indicators of AMOC variability over the last deglacial, we reconstructed Mg/Ca-temperature and δ18O records from surface (G. ruber) and deeper thermocline dwelling (G. truncatulinoides, 200 - 500 m depth habitat) planktonic foraminifera from southern Caribbean Sea core VM12-107 (11.33oN, 66.63oW; 1079 m; 15 cm/kyr sedimentation rate). As a result, we present the first deglacial subsurface Mg/Ca-temperature record for this region. Results show that glacial sea surface temperatures (SST) were 4oC cooler than those in the late Holocene. SSTs during the deglacial show little or no SST rise (1oC) during Heinrich Event 1 (H1), and a 2oC SST decrease during the Younger Dryas (YD). In contrast, last glacial maximum subsurface temperatures were 2oC warmer than Late Holocene values of 12 - 13oC and periods of reduced AMOC are marked by abrupt subsurface warming events. Subsurface temperatures increased by almost 3oC during H1 and the YD, warming to as much as 16.5oC. Furthermore, a comparison of

  9. BIODEGRADATION OF ATRAZINE IN SUBSURFACE ENVIRONMENTS

    EPA Science Inventory

    The pesticide atrazine is frequently detected in ground water, including ground water used as drinking water. Little information is available on the fate of atrazine in the subsurface, including its biodegradability. The objectives of this study were to evaluate the biodegradabil...

  10. Is Europa's Subsurface Water Ocean Warm?

    NASA Technical Reports Server (NTRS)

    Melosh, H. J.; Ekholm, A. G.; Showman, A. P.; Lorenz, R. D.

    2002-01-01

    Europa's subsurface water ocean may be warm: that is, at the temperature of water's maximum density. This provides a natural explanation of chaos melt-through events and leads to a correct estimate of the age of its surface. Additional information is contained in the original extended abstract.

  11. Methods for forming long subsurface heaters

    SciTech Connect

    Kim, Dong Sub

    2013-09-17

    A method for forming a longitudinal subsurface heater includes longitudinally welding an electrically conductive sheath of an insulated conductor heater along at least one longitudinal strip of metal. The longitudinal strip is formed into a tubular around the insulated conductor heater with the insulated conductor heater welded along the inside surface of the tubular.

  12. Subsurface manure application to reduce ammonia emissions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Incorporation into soil is generally recommended to reduce ammonia volatilization and nutrient runoff following land application of manures. A range of subsurface applicators are available for manure incorporation with minimal soil disturbance in reduced tillage systems, but none have been widely a...

  13. Lateral gene transfer in the subsurface

    SciTech Connect

    Barkay, Tamar; Sobecky, Patricia

    2007-08-27

    Lateral gene transfer (LGT) is an important adaptive mechanism among prokaryotic organisms. This mechanism is particularly important for the response of microorganisms to changing environmental conditions because it facilitates the transfer of a large number of genes and their rapid expression. Together the transferred genes promote rapid genetic and metabolic changes that may enhance survival to newly established and sometimes hostile environmental conditions. The goal of our project was to examine if and how LGT enhances microbial adaptation to toxic heavy metals in subsurface environments that had been contaminated by mixed wastes due to activities associated with the production of nuclear energy and weapons. This task has been accomplished by dividing the project to several sub-tasks. Thus, we: (1) Determined the level of resistance of subsurface bacterial isolates to several toxic metals, all identified as pollutants of concern in subsurface environments; (2) Designed, tested, and applied, a molecular approach that determined whether metal resistance genes had evolved by LGT among subsurface bacteria; and (3) Developed a DNA hybridization array for the identification of broad host range plasmids and of metal resistance plasmids. The results are briefly summarized below with references to published papers and manuscripts in preparation where details about our research can be found. Additional information may be found in copies of our published manuscripts and conference proceedings, and our yearly reports that were submitted through the RIMS system.

  14. Biomarker Preservation Potential of Subsurface Ecosystems

    NASA Astrophysics Data System (ADS)

    Onstott, T. C.; Harris, R. L.; Sherwood Lollar, B.; Pedersen, K. A.; Colwell, F. S.; Pfiffner, S. M.; Phelps, T. J.; Kieft, T. L.; Bakermans, C.

    2016-05-01

    If surface life emerged on Mars it may have succumbed to a Gaian bottleneck, whereas subsurface life would have continued to grow and evolve sheltered in rocks with sub-freezing saline pore water and their remains preserved in excavated rock.

  15. Irrigation strategies using subsurface drip irrigation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Subsurface drip irrigation (SDI) is practiced on approximately 60,000 ha in the Texas High Plains region of the USA. Adoption of SDI continues to increase in the region. This has been attributed to record drought in Texas and the US Southwest in recent years, declining irrigation well yields, and ev...

  16. Liquid cryobrines in the subsurface of Mars

    NASA Astrophysics Data System (ADS)

    Möhlmann, Diedrich

    Liquid cryobrines in the subsurface of Mars D. Mühlmann, DLR Institut für Planetenforschung, Berlin (dirk.moehlmann@dlr.de) Thermodynamics shows that undercooled liquid interfacial water must necessarily exist in the upper surface of Mars, at least temporarily. In case of a given presence of soluble salt grains in the soil with attached interfacial water (of atmospheric-or ice-origin) there must evolve liquid brines ("cryobrines"). The eutectic temperature of cryobrines can be far below 0 C and numerous known brines will remain liquid at martian temperatures. Liquid cryobrines are therefore expected to exist at appropriate sites in the subsurface of Mars, at least temporarily but also at present. Properties like eutectic phase diagrams, related water activity and stability of "Mars-relevant" salts and brines under current martian atmospheric conditions are presented and discussed. It is described that the presence of at least temporarily liquid cryobrines in the subsurface soil can be related to rheological phenomena of viscous liquid brines, and that liquid cryobrines are a current challenge in view of their possible support to a habitability of the subsurface of Mars.

  17. Surface and subsurface oxygen on Pd(111)

    NASA Astrophysics Data System (ADS)

    Leisenberger, F. P.; Koller, G.; Sock, M.; Surnev, S.; Ramsey, M. G.; Netzer, F. P.; Klötzer, B.; Hayek, K.

    2000-01-01

    The interaction of O2 with Pd(111) in the temperature range from 300 K to 1000 K was studied by molecular beam adsorption, thermal desorption (TDS), low energy electron diffraction (LEED), high-resolution X-ray photoelectron spectroscopy (XPS) and high-resolution electron energy loss spectroscopy (HREELS). Using a capillary array doser and high effective oxygen pressures, evidence was found for the formation of a densely packed chemisorbed oxygen adlayer saturating at ΘO close to 1 and separately for subsurface migration of oxygen at elevated temperatures, but not at room temperature and below. Up to completion of a p(2×2) oxygen adlayer at 0.25 ML surface coverage, the dissociative sticking probability of oxygen into the chemisorbed state is high and masks the much slower diffusion into the bulk. Beyond 0.25 ML surface coverage, the adsorption rate into the chemisorbed state becomes small and the influence of bulk migration detectable. Exposure of the sample to high oxygen dosages at 1000 K fills up the subsurface reservoir and subsequent sticking measurements are no longer influenced by oxygen loss to the bulk. The subsurface oxygen could be distinguished in both XPS and off-specular HREELS. These latter techniques revealed that considerable concentrations of oxygen in the near-surface region can build up, even at lower temperatures (523 K) and oxygen exposures (40 L). In contrast to chemisorbed oxygen atoms on Pd(111), the subsurface species cannot be removed by reaction with CO.

  18. Holocene sea subsurface and surface water masses in the Fram Strait - Comparisons of temperature and sea-ice reconstructions

    NASA Astrophysics Data System (ADS)

    Werner, Kirstin; Müller, Juliane; Husum, Katrine; Spielhagen, Robert F.; Kandiano, Evgenia S.; Polyak, Leonid

    2016-09-01

    Two high-resolution sediment cores from eastern Fram Strait have been investigated for sea subsurface and surface temperature variability during the Holocene (the past ca 12,000 years). The transfer function developed by Husum and Hald (2012) has been applied to sediment cores in order to reconstruct fluctuations of sea subsurface temperatures throughout the period. Additional biomarker and foraminiferal proxy data are used to elucidate variability between surface and subsurface water mass conditions, and to conclude on the Holocene climate and oceanographic variability on the West Spitsbergen continental margin. Results consistently reveal warm sea surface to subsurface temperatures of up to 6 °C until ca 5 cal ka BP, with maximum seawater temperatures around 10 cal ka BP, likely related to maximum July insolation occurring at that time. Maximum Atlantic Water (AW) advection occurred at surface and subsurface between 10.6 and 8.5 cal ka BP based on both foraminiferal and dinocyst temperature reconstructions. Probably, a less-stratified, ice-free, nutrient-rich surface ocean with strong AW advection prevailed in the eastern Fram Strait between 10 and 9 cal ka BP. Weakened AW contribution is found after ca 5 cal ka BP when subsurface temperatures strongly decrease with minimum values between ca 4 and 3 cal ka BP. Cold late Holocene conditions are furthermore supported by high planktic foraminifer shell fragmentation and high δ18O values of the subpolar planktic foraminifer species Turborotalita quinqueloba. While IP25-associated indices as well as dinocyst data suggest a sustained cooling due to a decrease in early summer insolation and consequently sea-ice increase since about 7 cal ka BP in surface waters, planktic foraminiferal data including stable isotopes indicate a slight return of stronger subsurface AW influx since ca 3 cal ka BP. The observed decoupling of surface and subsurface waters during the later Holocene is most likely attributed to a strong

  19. Impact of agricultural activities on anaerobic processes in stream sediments

    NASA Astrophysics Data System (ADS)

    Schade, J. D.; Ludwig, S.; Nelson, L. C.; Porterfield, J.; Sather, K. L.; Songpitak, M.; Spawn, S.; Weigel, B.

    2013-12-01

    Streams draining agriculture watersheds are subject to significant anthropogenic impacts, including sedimentation from soil erosion and high nitrate input from heavy fertilizer application. Sedimentation degrades habitat and can reduce hydrologic exchange between surface and subsurface waters. Disconnecting surface and subsurface flow reduces oxygen input to hyporheic water, increasing the extent of anoxic zones in stream sediments and creating hotspots for anaerobic processes like denitrification and methanogenesis that can be important sources of nitrous oxide and methane, both powerful greenhouse gases. Increased nitrate input may influence greenhouse gas fluxes from stream sediments by stimulating rates of denitrification and potentially reducing rates of methanogenesis, either through direct inhibition or by increasing competition for organic substrates from denitrifying bacteria. We hypothesized that accumulation of fine sediments in stream channels would result in high rates of methanogenesis in stream sediments, and that increased nitrate input from agricultural runoff would stimulate denitrification and reduce rates of methane production. Our work focused on streams in northern and central Minnesota, in particular on Rice Creek, a small stream draining an agricultural watershed. We used a variety of approaches to test our hypotheses, including surveys of methane concentrations in surface waters of streams ranging in sediment type and nitrate concentration, bottle incubations of sediment from several sites in Rice Creek, and the use of functional gene probes and RNA analyses to determine if genes for these processes are present and being expressed in stream sediments. We found higher methane concentrations in surface water from streams with large deposits of fine sediments, but significantly less methane in these streams when nitrate concentrations were high. We also found high potential for both methanogenesis and denitrification in sediment incubations

  20. Fate of Magnesium Chloride Brine Applied to Suppress Dust from Unpaved Roads at the INEEL Subsurface Disposal Area

    SciTech Connect

    Larry Hull; Carolyn Bishop

    2004-02-01

    Between 1984 and 1993, MgCl2 brine was used to suppress dust on unpaved roads at a radioactive waste subsurface disposal area. Because Cl– might enhance corrosion of buried metals in the waste, we investigated the distribution and fate of Cl– in the vadose zone using pore water samples collected from suction lysimeters and soluble salt concentrations extracted from sediment samples. The Cl/Br mass ratio and the total dissolved Cl– concentration of pore water show that brine contamination occurs primarily within 13 m of treated roads, but can extend as much as 30 m laterally in near-surface sedimentary deposits. Within the deep vadose zone, which consists of interlayered basalt lava flows and sedimentary interbeds, brine has moved up to 110 m laterally. This lateral migration suggests formation of perched water and horizontal transport during periods of high recharge. In a few locations, brine migrated to depths of 67 m within 3 to 5 yr. Elevated Cl– concentrations were found to depths of 2 m in roadbed material. In drainage ditches along roads, where runoff accumulates and recharge of surface water is high, Cl– was flushed from the sediments in 3 to 4 yr. In areas of lower recharge, Cl– remained in the sediments after 5 yr. Vertical brine movement is directly related to surface recharge through sediments. The distribution of Cl– in pore water and sediments is consistent with estimates of vadose zone residence times and spatial distribution of surface water recharge from other investigations at the subsurface

  1. Subsurface geological modeling of Corrientes province (NE Argentina) and its relationships with the Guaraní Aquifer system function

    NASA Astrophysics Data System (ADS)

    Mira, Andrés; Veroslavsky, Gerardo; Rossello, Eduardo; Vives, Luis; Rodríguez, Leticia

    2015-10-01

    From the integration results of geological and geophysical data, a subsurface geological model of the Corrientes province (Argentina) that allows visualizing its deep geological structure and how it affected the Guaraní Aquifer System (GAS) is presented. 44 boreholes, 21 geophysical surveys and 1366 depth data from a Bouguer gravity anomaly model have been used. The model was built from five layers easily distinguishable in the regional subsurface: basement, pre-GAS sediments (Paleozoic), GAS sediments (Triassic-Lower Cretaceous), basalts (Serra Geral Group, Lower Cretaceous) and post basaltic sediments. The resulting geometry shows a basement with a structural high, the Dorsal Asunción-Rio Grande, where the GAS and the basaltic layer are thinner and the Mesozoic sediments rise near the surface. It is an area prone to local recharge and regional discharge of the GAS and it is in line with the latest piezometry and groundwater chemical analysis. Furthermore, two important depocenters have been identified, Corrientes and Curuzú structural high blocks, with at least 3500 m of sedimentary and volcano-sedimentary deposits that suggest the existence of significant pre-carboniferous sediment units associated to ancient extensional structures of the early Paleozoic. The proposed model allows defining a lithostratigraphic column of Corrientes and gives new criteria to redraw the southwest limit of the GAS.

  2. IODP Exp 331: Iron-oxidizing Bacteria from the Okinawa Trough Deep Subsurface Biosphere

    NASA Astrophysics Data System (ADS)

    Moyer, C. L.; McAllister, S. M.

    2011-12-01

    Communities of Fe-oxidizing Bacteria (FeOB) are common at sites of hydrothermal venting and are known to form complex communities in microbial mats, hydrothermal sediments, and borehole fluids. Studies at sites around the Pacific Ocean have found the Zetaproteobacteria to be dominant members of these FeOB communities. Preliminary culture-independent analyses indicate that borehole fluids from the deep subsurface may support several novel and distinct Zetaproteobacteria phylotypes (McAllister et al., 2011). Sampling from the deep subsurface at the Iheya North hydrothermal field has provided an opportunity to explore the microbial biodiversity of this unique subsurface habitat. Onboard enrichment experiments for FeOB were carried out at several sites over a wide range of depths as part of IODP Expedition 331. Enrichment experiments were carried out in both microaerophilic and anaerobic environments, with oxygen and nitrate as terminal electron acceptors, respectively. Although tested for the presence of FeOB from 0.23 to 42.45 meters below the seafloor (mbsf), Site C0014 showed little growth except for in the top half meter of hydrothermally unaltered, weakly oxidized sediment. Site C0015, which was diffusely venting and had a relatively low-temperature (~15°C), showed growth throughout the hole with both microaerophilic and anaerobic conditions to a depth of nine mbsf. Growth at this low-temperature site is consistent with previous studies of iron-oxidizing communities, and may correlate best with the borehole community at the Southern Mariana Trough (Kato et al., 2009). At Site C0017, a potential zone of recharge flow (down-welling of cold oxygenated seawater) was traversed from ~26 to 35 mbsf, and at the top of this zone the microaerophilic enrichment experiments showed growth. Growth in this recharge zone represents the deepest subsurface cultivation of FeOB to date, and may lend insight into the colonization of low-temperature vent systems via subsurface fluid

  3. 29 CFR 1960.67 - Federal agency certification of the injury and illness annual summary (OSHA 300-A or equivalent).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 300-A or equivalent). As required by 29 CFR 1904.32, a company executive must certify that he or she has examined the OSHA 300 Log and that he or she believes, based on his or her knowledge of the... senior establishment management official, (b) The head of the Agency for which the senior...

  4. 29 CFR 1960.67 - Federal agency certification of the injury and illness annual summary (OSHA 300-A or equivalent).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 300-A or equivalent). As required by 29 CFR 1904.32, a company executive must certify that he or she has examined the OSHA 300 Log and that he or she believes, based on his or her knowledge of the... senior establishment management official, (b) The head of the Agency for which the senior...

  5. 29 CFR 1960.67 - Federal agency certification of the injury and illness annual summary (OSHA 300-A or equivalent).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 300-A or equivalent). As required by 29 CFR 1904.32, a company executive must certify that he or she has examined the OSHA 300 Log and that he or she believes, based on his or her knowledge of the... senior establishment management official, (b) The head of the Agency for which the senior...

  6. 7 CFR 330.300a - Administrative instructions exempting soil from parts of Canada from certain restrictions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 5 2014-01-01 2014-01-01 false Administrative instructions exempting soil from parts... FEDERAL PLANT PEST REGULATIONS; GENERAL; PLANT PESTS; SOIL, STONE, AND QUARRY PRODUCTS; GARBAGE Movement of Soil, Stone, And Quarry Products § 330.300a Administrative instructions exempting soil from...

  7. 7 CFR 330.300a - Administrative instructions exempting soil from parts of Canada from certain restrictions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 5 2013-01-01 2013-01-01 false Administrative instructions exempting soil from parts... FEDERAL PLANT PEST REGULATIONS; GENERAL; PLANT PESTS; SOIL, STONE, AND QUARRY PRODUCTS; GARBAGE Movement of Soil, Stone, And Quarry Products § 330.300a Administrative instructions exempting soil from...

  8. 7 CFR 330.300a - Administrative instructions exempting soil from parts of Canada from certain restrictions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 5 2010-01-01 2010-01-01 false Administrative instructions exempting soil from parts... FEDERAL PLANT PEST REGULATIONS; GENERAL; PLANT PESTS; SOIL, STONE, AND QUARRY PRODUCTS; GARBAGE Movement of Soil, Stone, And Quarry Products § 330.300a Administrative instructions exempting soil from...

  9. 7 CFR 330.300a - Administrative instructions exempting soil from parts of Canada from certain restrictions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 5 2012-01-01 2012-01-01 false Administrative instructions exempting soil from parts... FEDERAL PLANT PEST REGULATIONS; GENERAL; PLANT PESTS; SOIL, STONE, AND QUARRY PRODUCTS; GARBAGE Movement of Soil, Stone, And Quarry Products § 330.300a Administrative instructions exempting soil from...

  10. 7 CFR 330.300a - Administrative instructions exempting soil from parts of Canada from certain restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 5 2011-01-01 2011-01-01 false Administrative instructions exempting soil from parts... FEDERAL PLANT PEST REGULATIONS; GENERAL; PLANT PESTS; SOIL, STONE, AND QUARRY PRODUCTS; GARBAGE Movement of Soil, Stone, And Quarry Products § 330.300a Administrative instructions exempting soil from...

  11. The T300A Crohn's disease risk polymorphism impairs function of the WD40 domain of ATG16L1.

    PubMed

    Boada-Romero, Emilio; Serramito-Gómez, Inmaculada; Sacristán, María P; Boone, David L; Xavier, Ramnik J; Pimentel-Muiños, Felipe X

    2016-01-01

    A coding polymorphism of human ATG16L1 (rs2241880; T300A) increases the risk of Crohn's disease and it has been shown to enhance susceptibility of ATG16L1 to caspase cleavage. Here we show that T300A also alters the ability of the C-terminal WD40-repeat domain of ATG16L1 to interact with an amino acid motif that recognizes this region. Such alteration impairs the unconventional autophagic activity of TMEM59, a transmembrane protein that contains the WD40 domain-binding motif, and disrupts its normal intracellular trafficking and its ability to engage ATG16L1 in response to bacterial infection. TMEM59-induced autophagy is blunted in cells expressing the fragments generated by caspase processing of the ATG16L1-T300A risk allele, whereas canonical autophagy remains unaffected. These results suggest that the T300A polymorphism alters the function of motif-containing molecules that engage ATG16L1 through the WD40 domain, either by influencing this interaction under non-stressful conditions or by inhibiting their downstream autophagic signalling after caspase-mediated cleavage. PMID:27273576

  12. The T300A Crohn's disease risk polymorphism impairs function of the WD40 domain of ATG16L1

    PubMed Central

    Boada-Romero, Emilio; Serramito-Gómez, Inmaculada; Sacristán, María P.; Boone, David L.; Xavier, Ramnik J.; Pimentel-Muiños, Felipe X.

    2016-01-01

    A coding polymorphism of human ATG16L1 (rs2241880; T300A) increases the risk of Crohn's disease and it has been shown to enhance susceptibility of ATG16L1 to caspase cleavage. Here we show that T300A also alters the ability of the C-terminal WD40-repeat domain of ATG16L1 to interact with an amino acid motif that recognizes this region. Such alteration impairs the unconventional autophagic activity of TMEM59, a transmembrane protein that contains the WD40 domain-binding motif, and disrupts its normal intracellular trafficking and its ability to engage ATG16L1 in response to bacterial infection. TMEM59-induced autophagy is blunted in cells expressing the fragments generated by caspase processing of the ATG16L1-T300A risk allele, whereas canonical autophagy remains unaffected. These results suggest that the T300A polymorphism alters the function of motif-containing molecules that engage ATG16L1 through the WD40 domain, either by influencing this interaction under non-stressful conditions or by inhibiting their downstream autophagic signalling after caspase-mediated cleavage. PMID:27273576

  13. Linear absorption coefficient of beryllium in the 50-300-A wavelength range. [bandpass filter materials for ultraviolet astronomy instrumentation

    NASA Technical Reports Server (NTRS)

    Barstow, M. A.; Lewis, M.; Petre, R.

    1983-01-01

    Transmittances of thin-film filters fabricated for an extreme-UV astronomy sounding-rocket experiment yield values for the linear absorption coefficient of beryllium in the 50-300-A wavelength range, in which previous measurements are sparse. The inferred values are consistent with the lowest data previously published and may have important consequences for extreme-UV astronomers.

  14. Adsorption Behavior of Black Carbon for Radioactive Iodine Species in Subsurface Environments

    NASA Astrophysics Data System (ADS)

    Choung, S.; Kim, M.; Um, W.

    2012-12-01

    Releases of radioactive iodines (125/129/131I) into subsurface environments occur during nuclear power plant operations, nuclear weapons tests, and nuclear accidents such as Chernobyl and Fukushima. Environmental concern is mostly for 129I due to high toxicity and long-half life, t1/2=1,600,000 years. The fate and transport of radioactive iodines depend on the speciation in the environments. Sorption of iodate (IO3-) is strongly affected by natural organic matter (NOM) in soil/sediments, while iodide (I-) sorption is less. Although there are numerous forms and compositions of NOM in soil/sediments, previous studies were mostly focused on general organic matter such as humic and fulvic acids. The objective of this study is addressed to evaluate the impact of black carbon as different NOM forms in subsurface environments. Laboratory-produced wood char was used as a representative of black carbon for sorption batch experiments. Commercial humic acid was added to experiments for comparison of iodine sorption behavior to black carbon material. Stable iodine isotope, 127I, was used as a surrogate of radioactive iodine. The 13C-NMR analyses indicated that the wood char consisted of dominantly aromatic chemical structures, while the humic acid exhibited relatively more aliphatic structures than aromaticity. The char and humic acid significantly increased iodide and iodate sorption, respectively. However, iodate sorption on char and iodide sorption on humic acid were negligible in this study. These observations implied different sorption mechanisms between black carbon and humic acid due to different pore structures and chemical compositions. Both of sorption isotherms are dependent on aqueous concentrations, following Freundlich isotherm with n~0.7. The sorption behavior and mechanism of iodine is significantly influenced by the NOM types in soils and sediments, which can enhance iodine retardation in the subsurface environment.

  15. Environmental parameters controlling microbial activities in terrestrial subsurface environments. Technical completion report

    SciTech Connect

    Kieft, T.L.

    1990-12-31

    This project was begun in July 1988 as part of Phase I of the Deep Microbiology Subprogram. At this time, the Subprogram was preparing for sampling near the Savannah River Site (SRS) from what was being termed the ``Investigator`s Hole.`` This was the fourth hole drilled for sampling in the coastal plain sediments at a site near the SRS. Since there was a possibility of sampling from the saline Triassic basin in the deeper regions in this fourth hole, there was particular interest in quantifying halotolerant microorganisms from these samples and in determining the responses of subsurface microbes to a range of soft concentrations. Further interest in the soft tolerances of microbes from these coastal sediments arose from the fact that all of these sediments were deposited under marine conditions. It was also anticipated that samples would be available from the shallow unsaturated (vadose) zone at this site, so there was interest in quantifying microbial responses to matric water potential as well as solute water potential. The initial objectives of this research project were to: characterize microbial communities in a saline aquifer; determine the potential for microbial metabolism of selected organic compounds in a saline aquifers; characterize microbial communities in unsaturated subsurface materials (vadose zones); and determine the potential for microbial metabolism of selected organic compounds in unsaturated subsurface materials (vadose zones). Samples were collected from the borehole during a period extending from August to October 1988. A total of nine samples were express shipped to New Mexico Tech for analyses. These were all saturated zone samples from six different geological formations. Water contents and water potentials were measured at the time of sample arrival.

  16. Effects of nitrate on the stability of uranium in a bioreduced region of the subsurface.

    PubMed

    Wu, Wei-Min; Carley, Jack; Green, Stefan J; Luo, Jian; Kelly, Shelly D; Van Nostrand, Joy; Lowe, Kenneth; Mehlhorn, Tonia; Carroll, Sue; Boonchayanant, Benjaporn; Löfller, Frank E; Watson, David; Kemner, Kenneth M; Zhou, Jizhong; Kitanidis, Peter K; Kostka, Joel E; Jardine, Philip M; Criddle, Craig S

    2010-07-01

    The effects of nitrate on the stability of reduced, immobilized uranium were evaluated in field experiments at a U.S. Department of Energy site in Oak Ridge, TN. Nitrate (2.0 mM) was injected into a reduced region of the subsurface containing high levels of previously immobilized U(IV). The nitrate was reduced to nitrite, ammonium, and nitrogen gas; sulfide levels decreased; and Fe(II) levels increased then deceased. Uranium remobilization occurred concomitant with nitrite formation, suggesting nitrate-dependent, iron-accelerated oxidation of U(IV). Bromide tracer results indicated changes in subsurface flowpaths likely due to gas formation and/or precipitate. Desorption-adsorption of uranium by the iron-rich sediment impacted uranium mobilization and sequestration. After rereduction of the subsurface through ethanol additions, background groundwater containing high levels of nitrate was allowed to enter the reduced test zone. Aqueous uranium concentrations increased then decreased. Clone library analyses of sediment samples revealed the presence of denitrifying bacteria that can oxidize elemental sulfur, H(2)S, Fe(II), and U(IV) (e.g., Thiobacillus spp.), and a decrease in relative abundance of bacteria that can reduce Fe(III) and sulfate. XANES analyses of sediment samples confirmed changes in uranium oxidation state. Addition of ethanol restored reduced conditions and triggered a short-term increase in Fe(II) and aqueous uranium, likely due to reductive dissolution of Fe(III) oxides and release of sorbed U(VI). After two months of intermittent ethanol addition, sulfide levels increased, and aqueous uranium concentrations gradually decreased to <0.1 microM.

  17. Uranium(IV) Complexation by Natural Organic Matter Controls Speciation in the Subsurface

    NASA Astrophysics Data System (ADS)

    Bone, S.; Dynes, J.; Fendorf, S. E.; Jones, M. E.; Bargar, J.

    2014-12-01

    Uranium contaminates groundwater at many sites throughout the United States. At the aquifer in Rifle, CO, U(IV) has been found to accumulate in natural organic matter (NOM)-rich sediments comprising buried alluvial material. We expect that NOM, which is composed of detrital plant material and microbial biomass and necromass, profoundly influences the speciation of U(IV). Specifically, we hypothesize that NOM forms stable complexes with U(IV) (i.e., "noncrystalline" U(IV)), particularly through organic phosphorus moieties associated with bacteria and exopolymeric substances (EPS). Complexation with NOM can help to explain why noncrystalline U(IV) is more abundant in the subsurface than the mineral uraninite (UO2). The abundance and relative reactivity of non-crystalline U(IV) suggests that it drives U fate and transport in the subsurface. W are examining the reduction of U(VI) and subsequent complexation of U(IV) in model NOM systems comprising homogenized, partially degraded plant material, which is analogous to the detrital plant material abundant in Rifle sediments, and its associated microbial consortia. We employ a suite of spectroscopic (X-ray absorption spectroscopies) and microscopic (scanning transmission X-ray microscopy, scanning electron microscopy, and nano-scale secondary ion mass spectrometry) tools that allow us to identify the number and types of coordinating ligands and the distribution of U with respect to NOM components, including bacterial cells, plant matter and entrained minerals. In preliminary experiments we found that 50 - 100 % of U(VI) was reduced to U(IV) within several days. Furthermore, NOM was observed to sorb both U(VI), as a carbonyl complex, and U(IV), possibly as a phosphoryl complex. Further microscopic analyses are designed to elucidate whether U(IV)-P complexes are associated with bacteria or EPS. Our research suggests a new, more complicated model for U(IV) speciation in subsurface sediments, in which complexation by NOM, as

  18. Quantifying nonisothermal subsurface soil water evaporation

    NASA Astrophysics Data System (ADS)

    Deol, Pukhraj; Heitman, Josh; Amoozegar, Aziz; Ren, Tusheng; Horton, Robert

    2012-11-01

    Accurate quantification of energy and mass transfer during soil water evaporation is critical for improving understanding of the hydrologic cycle and for many environmental, agricultural, and engineering applications. Drying of soil under radiation boundary conditions results in formation of a dry surface layer (DSL), which is accompanied by a shift in the position of the latent heat sink from the surface to the subsurface. Detailed investigation of evaporative dynamics within this active near-surface zone has mostly been limited to modeling, with few measurements available to test models. Soil column studies were conducted to quantify nonisothermal subsurface evaporation profiles using a sensible heat balance (SHB) approach. Eleven-needle heat pulse probes were used to measure soil temperature and thermal property distributions at the millimeter scale in the near-surface soil. Depth-integrated SHB evaporation rates were compared with mass balance evaporation estimates under controlled laboratory conditions. The results show that the SHB method effectively measured total subsurface evaporation rates with only 0.01-0.03 mm h-1difference from mass balance estimates. The SHB approach also quantified millimeter-scale nonisothermal subsurface evaporation profiles over a drying event, which has not been previously possible. Thickness of the DSL was also examined using measured soil thermal conductivity distributions near the drying surface. Estimates of the DSL thickness were consistent with observed evaporation profile distributions from SHB. Estimated thickness of the DSL was further used to compute diffusive vapor flux. The diffusive vapor flux also closely matched both mass balance evaporation rates and subsurface evaporation rates estimated from SHB.

  19. Alternative filter media for phosphorous removal in a horizontal subsurface flow constructed wetland.

    PubMed

    Vohla, Christina; Põldvere, Elar; Noorvee, Alar; Kuusemets, Valdo; Mander, Ulo

    2005-01-01

    During the study period from 1997 to 2002 the purification efficiency of phosphorus in the horizontal subsurface flow (HSSF) constructed wetland (CW) in Kodijärve, has been quite high (63-95%). However, slowly increasing trend in outlet P concentrations and decreasing annual P removal rate are obviously the indicators that show possible saturation processes in filter media. To search for potential filter media with high phosphorus sorption capacity, sorption characteristics and particle size distribution of several local sands, gravels, glauconite-sandstone, LWA, and calcareous waste products from oil-shale industry were investigated. The average P sorption capacity for best materials (crashed ash block, oil, shale fly ash and the sediment from oil shale ash plateau) was higher than 96% and estimated design capacity was around 4-5 g P kg(-1). According to results, sediment from oil shale ash plateau was considered as perspective filter media for P retention. In Summer 2002 experimental sedimentation filter, filled with the sediment from oil shale ash plateau, was installed in the outlet from the Kodijärve HSSF CW. According to preliminary results the average P removal in the sedimentation filter was 52%. PMID:15921280

  20. Dissimilatory Iron Reduction by Microorganisms Under Hot Deep Subsurface Conditions

    NASA Astrophysics Data System (ADS)

    Ruper, S.; Sharma, A.; Scott, J. H.

    2010-04-01

    In subsurface environments the availability of terminal electron acceptors will be the major biogeochemical constraint, before temperature or pressure begin plays a role. Data is presented to show the impact of deep hot subsurface conditions on dissimilatory iron reduction.

  1. Trajectories of Microbial Community Function in Response to Accelerated Remediation of Subsurface Metal Contaminants

    SciTech Connect

    Firestone, Mary

    2015-01-14

    Objectives of proposed research were to; Determine if the trajectories of microbial community composition and function following organic carbon amendment can be related to, and predicted by, key environmental determinants; Assess the relative importance of the characteristics of the indigenous microbial community, sediment, groundwater, and concentration of organic carbon amendment as the major determinants of microbial community functional response and bioremediation capacity; and Provide a fundamental understanding of the microbial community ecology underlying subsurface metal remediation requisite to successful application of accelerated remediation and long-term stewardship of DOE-IFC sites.

  2. Microbial abundance in the deep subsurface of the Chesapeake Bay impact crater: relationship to lithology and impact processes

    USGS Publications Warehouse

    Cockell, Charles S.; Gronstal, Aaron L.; Voytek, Mary A.; Kirshtein, Julie D.; Finster, Kai; Sanford, Ward E.; Glamoclija, Mihaela; Gohn, Gregroy S.; Powars, David S.; Horton, J. Wright

    2009-01-01

    Asteroid and comet impact events are known to cause profound disruption to surface ecosystems. The aseptic collection of samples throughout a 1.76-km-deep set of cores recovered from the deep subsurface of the Chesapeake Bay impact structure has allowed the study of the subsurface biosphere in a region disrupted by an impactor. Microbiological enumerations suggest the presence of three major microbiological zones. The upper zone (127–867 m) is characterized by a logarithmic decline in microbial abundance from the surface through the postimpact section of Miocene to Upper Eocene marine sediments and across the transition into the upper layers of the impact tsunami resurge sediments and sediment megablocks. In the middle zone (867–1397 m) microbial abundances are below detection. This zone is predominantly quartz sand, primarily composed of boulders and blocks, and it may have been mostly sterilized by the thermal pulse delivered during impact. No samples were collected from the large granite block (1096–1371 m). The lowest zone (below 1397 m) of increasing microbial abundance coincides with a region of heavily impact-fractured, hydraulically conductive suevite and fractured schist. These zones correspond to lithologies influenced by impact processes. Our results yield insights into the influence of impacts on the deep subsurface biosphere.

  3. Microbial mineral colonization across a subsurface redox transition zone

    DOE PAGES

    Converse, Brandon J.; McKinley, James P.; Resch, Charles T.; Roden, Eric E.

    2015-08-28

    Here our study employed 16S rRNA gene amplicon pyrosequencing to examine the hypothesis that chemolithotrophic Fe(II)-oxidizing bacteria (FeOB) would preferentially colonize the Fe(II)-bearing mineral biotite compared to quartz sand when the minerals were incubated in situ within a subsurface redox transition zone (RTZ) at the Hanford 300 Area site in Richland, WA, USA. The work was motivated by the recently documented presence of neutral-pH chemolithotrophic FeOB capable of oxidizing structural Fe(II) in primary silicate and secondary phyllosilicate minerals in 300 Area sediments and groundwater (Benzine et al., 2013). Sterilized portions of sand+biotite or sand alone were incubated in situ formore » 5 months within a multilevel sampling (MLS) apparatus that spanned a ca. 2-m interval across the RTZ in two separate groundwater wells. Parallel MLS measurements of aqueous geochemical species were performed prior to deployment of the minerals. Contrary to expectations, the 16S rRNA gene libraries showed no significant difference in microbial communities that colonized the sand+biotite vs. sand-only deployments. Both mineral-associated and groundwater communities were dominated by heterotrophic taxa, with organisms from the Pseudomonadaceae accounting for up to 70% of all reads from the colonized minerals. These results are consistent with previous results indicating the capacity for heterotrophic metabolism (including anaerobic metabolism below the RTZ) as well as the predominance of heterotrophic taxa within 300 Area sediments and groundwater. Although heterotrophic organisms clearly dominated the colonized minerals, several putative lithotrophic (NH4+, H2, Fe(II), and HS- oxidizing) taxa were detected in significant abundance above and within the RTZ. Such organisms may play a role in the coupling of anaerobic microbial metabolism to oxidative pathways with attendant impacts on elemental cycling and redox-sensitive contaminant behavior in the vicinity of the RTZ.« less

  4. A subsurface model of the beaver meadow complex

    NASA Astrophysics Data System (ADS)

    Nash, C.; Grant, G.; Flinchum, B. A.; Lancaster, J.; Holbrook, W. S.; Davis, L. G.; Lewis, S.

    2015-12-01

    Wet meadows are a vital component of arid and semi-arid environments. These valley spanning, seasonally inundated wetlands provide critical habitat and refugia for wildlife, and may potentially mediate catchment-scale hydrology in otherwise "water challenged" landscapes. In the last 150 years, these meadows have begun incising rapidly, causing the wetlands to drain and much of the ecological benefit to be lost. The mechanisms driving this incision are poorly understood, with proposed means ranging from cattle grazing to climate change, to the removal of beaver. There is considerable interest in identifying cost-effective strategies to restore the hydrologic and ecological conditions of these meadows at a meaningful scale, but effective process based restoration first requires a thorough understanding of the constructional history of these ubiquitous features. There is emerging evidence to suggest that the North American beaver may have had a considerable role in shaping this landscape through the building of dams. This "beaver meadow complex hypothesis" posits that as beaver dams filled with fine-grained sediments, they became large wet meadows on which new dams, and new complexes, were formed, thereby aggrading valley bottoms. A pioneering study done in Yellowstone indicated that 32-50% of the alluvial sediment was deposited in ponded environments. The observed aggradation rates were highly heterogeneous, suggesting spatial variability in the depositional process - all consistent with the beaver meadow complex hypothesis (Polvi and Wohl, 2012). To expand on this initial work, we have probed deeper into these meadow complexes using a combination of geophysical techniques, coring methods and numerical modeling to create a 3-dimensional representation of the subsurface environments. This imaging has given us a unique view into the patterns and processes responsible for the landforms, and may shed further light on the role of beaver in shaping these landscapes.

  5. Microbial mineral colonization across a subsurface redox transition zone

    PubMed Central

    Converse, Brandon J.; McKinley, James P.; Resch, Charles T.; Roden, Eric E.

    2015-01-01

    This study employed 16S rRNA gene amplicon pyrosequencing to examine the hypothesis that chemolithotrophic Fe(II)-oxidizing bacteria (FeOB) would preferentially colonize the Fe(II)-bearing mineral biotite compared to quartz sand when the minerals were incubated in situ within a subsurface redox transition zone (RTZ) at the Hanford 300 Area site in Richland, WA, USA. The work was motivated by the recently documented presence of neutral-pH chemolithotrophic FeOB capable of oxidizing structural Fe(II) in primary silicate and secondary phyllosilicate minerals in 300 Area sediments and groundwater (Benzine et al., 2013). Sterilized portions of sand+biotite or sand alone were incubated in situ for 5 months within a multilevel sampling (MLS) apparatus that spanned a ca. 2-m interval across the RTZ in two separate groundwater wells. Parallel MLS measurements of aqueous geochemical species were performed prior to deployment of the minerals. Contrary to expectations, the 16S rRNA gene libraries showed no significant difference in microbial communities that colonized the sand+biotite vs. sand-only deployments. Both mineral-associated and groundwater communities were dominated by heterotrophic taxa, with organisms from the Pseudomonadaceae accounting for up to 70% of all reads from the colonized minerals. These results are consistent with previous results indicating the capacity for heterotrophic metabolism (including anaerobic metabolism below the RTZ) as well as the predominance of heterotrophic taxa within 300 Area sediments and groundwater. Although heterotrophic organisms clearly dominated the colonized minerals, several putative lithotrophic (NH4+, H2, Fe(II), and HS- oxidizing) taxa were detected in significant abundance above and within the RTZ. Such organisms may play a role in the coupling of anaerobic microbial metabolism to oxidative pathways with attendant impacts on elemental cycling and redox-sensitive contaminant behavior in the vicinity of the RTZ. PMID

  6. Microbial mineral colonization across a subsurface redox transition zone

    SciTech Connect

    Converse, Brandon J.; McKinley, James P.; Resch, Charles T.; Roden, Eric E.

    2015-08-28

    Here our study employed 16S rRNA gene amplicon pyrosequencing to examine the hypothesis that chemolithotrophic Fe(II)-oxidizing bacteria (FeOB) would preferentially colonize the Fe(II)-bearing mineral biotite compared to quartz sand when the minerals were incubated in situ within a subsurface redox transition zone (RTZ) at the Hanford 300 Area site in Richland, WA, USA. The work was motivated by the recently documented presence of neutral-pH chemolithotrophic FeOB capable of oxidizing structural Fe(II) in primary silicate and secondary phyllosilicate minerals in 300 Area sediments and groundwater (Benzine et al., 2013). Sterilized portions of sand+biotite or sand alone were incubated in situ for 5 months within a multilevel sampling (MLS) apparatus that spanned a ca. 2-m interval across the RTZ in two separate groundwater wells. Parallel MLS measurements of aqueous geochemical species were performed prior to deployment of the minerals. Contrary to expectations, the 16S rRNA gene libraries showed no significant difference in microbial communities that colonized the sand+biotite vs. sand-only deployments. Both mineral-associated and groundwater communities were dominated by heterotrophic taxa, with organisms from the Pseudomonadaceae accounting for up to 70% of all reads from the colonized minerals. These results are consistent with previous results indicating the capacity for heterotrophic metabolism (including anaerobic metabolism below the RTZ) as well as the predominance of heterotrophic taxa within 300 Area sediments and groundwater. Although heterotrophic organisms clearly dominated the colonized minerals, several putative lithotrophic (NH4+, H2, Fe(II), and HS- oxidizing) taxa were detected in significant abundance above and within the RTZ. Such organisms may play a role in the coupling of anaerobic microbial metabolism to oxidative pathways with attendant impacts on elemental cycling and redox-sensitive contaminant

  7. Denitrifying bacteria from the genus Rhodanobacter dominate bacterial communities in the highly contaminated subsurface of a nuclear legacy waste site

    SciTech Connect

    Green, Stefan; Prakash, Om; Jasrotia, Puja; Overholt, Will; Cardenas, Erick; Hubbard, Daniela; Tiedje, James M.; Watson, David B; Schadt, Christopher Warren; Brooks, Scott C; Kostka, Joel

    2011-01-01

    The effect of long-term mixed-waste contamination, particularly uranium and nitrate, on the microbial community in the terrestrial subsurface was investigated at the field scale at the Oak Ridge Integrated Field Research Challenge (ORIFRC) site in Oak Ridge, TN. The abundance, community composition, and distribution of groundwater microorganisms were examined across the site during two seasonal sampling events. At representative locations, subsurface sediment was also examined from two boreholes, one sampled from the most heavily contaminated area of the site and another from an area with low contamination. A suite of DNA- and RNA-based molecular tools were employed for community characterization, including quantitative PCR of ribosomal RNA and nitrite reductase genes, community composition fingerprinting analysis, and high-throughput pyrotag sequencing of rRNA genes. The results demonstrate that pH is a major driver of the subsurface microbial community structure, and denitrifying bacteria from the genus Rhodanobacter (class Gammaproteobacteria) dominate at low pH. The relative abundance of bacteria from this genus was positively correlated with lower pH conditions, and these bacteria were abundant and active in the most highly contaminated areas. Other factors, such as concentration of nitrogen species, oxygen and sampling season did not appear to strongly influence the distribution of Rhodanobacter. Results indicate that these organisms are acid-tolerant denitrifiers, well suited to the acidic, nitrate-rich subsurface conditions, and pH is confirmed as a dominant driver of bacterial community structure in this contaminated subsurface environment.

  8. Analysis of riverbed temperatures to determine the geometry of subsurface water flow around in-stream geomorphological structures

    NASA Astrophysics Data System (ADS)

    Munz, Matthias; Oswald, Sascha E.; Schmidt, Christian

    2016-08-01

    The analytical evaluation of diurnal temperature variation in riverbed sediments provides detailed information on exchange fluxes between rivers and groundwater. The underlying assumption of the stationary, one-dimensional vertical flow field is frequently violated in natural systems where subsurface water flow often has a significant horizontal component. In this paper, we present a new methodology for identifying the geometry of the subsurface flow field using vertical temperature profiles. The statistical analyses are based on model optimisation and selection and are used to evaluate the shape of vertical amplitude ratio profiles. The method was applied to multiple profiles measured around in-stream geomorphological structures in a losing reach of a gravel bed river. The predominant subsurface flow field was systematically categorised in purely vertical and horizontal (hyporheic, parafluvial) components. The results highlight that river groundwater exchange flux at the head, crest and tail of geomorphological structures significantly deviated from the one-dimensional vertical flow, due to a significant horizontal component. The geometry of the subsurface water flow depended on the position around the geomorphological structures and on the river level. The methodology presented in this paper features great potential for characterising the spatial patterns and temporal dynamics of complex subsurface flow geometries by using measured temperature time series in vertical profiles.

  9. The Mars Underground Mole (MUM): A Subsurface Penetration Device with Infrared Reflectance and Raman Spectroscopic Sensing Capability

    NASA Technical Reports Server (NTRS)

    Stoker, C. R.; Richter, L.; Smith, W. H.; Lemke, L. G.; Hammer, P.; Dalton, J. B.; Glass, B.; Zent, A.

    2003-01-01

    Searching for evidence of life on Mars will probably require access to the subsurface. The Martian surface is bathed in ultraviolet radiation which decomposes organic compounds, destroying possible evidence for life. Also, experiments performed by the Viking Landers imply the presence of several strongly oxidizing compounds at the Martian surface that may also play a role in destroying organic compounds near the surface. While liquid water is unstable on the Martian surface, and ice is unstable at the surface at low latitudes, recent results from the Mars Odyssey Gamma Ray Spectrometer experiment indicate that water ice is widely distributed near the surface under a thin cover of dry soil. Organic compounds created by an ancient Martian biosphere might be preserved in such ice-rich layers. Furthermore, accessing the subsurface provides a way to identify unique stratigraphy such as small-scale layering associated with lacustrine sediments. Subsurface access might also provide new insights into the Mars climate record that may be preserved in the Polar Layered Deposits. Recognizing the importance of accessing the subsurface of Mars to the future scientific exploration of the planet, the Mars Surveyor 2007 Science Definition Team called for drilling beneath the surface soils. Subsurface measurements are also cited as high priority in by MEPAG. Recognizing the importance of accessing the Martian subsurface to search for life, the European Space Agency has incorporated a small automated burrowing device called a subsurface penetrometer or Mole onto the Beagle 2 lander planned for 2003 launch. This device, called the Planetary Underground Tool (PLUTO), is a pointed slender cylinder 2 cm wide and 28 cm long equipped with a small sampling device at the pointed end that collects samples and brings them to the surface for analysis. Drawing on the PLUTO design, we are developing a larger Mole carrying sensors for identifying mineralogy, organic compounds, and water.

  10. In situ time-series measurements of subseafloor sediment properties

    USGS Publications Warehouse

    Wheatcroft, R.A.; Stevens, A.W.; Johnson, R.V.

    2007-01-01

    The capabilities and diversity of subsurface sediment sensors lags significantly from what is available for the water column, thereby limiting progress in understanding time-dependent seabed exchange and high-frequency acoustics. To help redress this imbalance, a new instrument, the autonomous sediment profiler (ASP), is described herein. ASP consists of a four-electrode, Wenner-type resistivity probe and a thermistor that log data at 0.1-cm vertical intervals over a 58-cm vertical profile. To avoid resampling the same spot on the seafloor, the probes are moved horizontally within a 20 times 100-cm-2 area in one of three preselected patterns. Memory and power capacities permit sampling at hourly intervals for up to 3-mo duration. The system was tested in a laboratory tank and shown to be able to resolve high-frequency sediment consolidation, as well as changes in sediment roughness. In a field test off the southern coast of France, the system collected resistivity and temperature data at hourly intervals for 16 d. Coupled with environmental data collected on waves, currents, and suspended sediment, the ASP is shown to be useful for understanding temporal evolution of subsurface sediment porosity, although no large depositional or erosional events occurred during the deployment. Following a rapid decrease in bottom-water temperature, the evolution of the subsurface temperature field was consistent with the 1-D thermal diffusion equation coupled with advection in the upper 3-4 cm. Collectively, the laboratory and field tests yielded promising results on time-dependent seabed change.

  11. Quantification of subsurface pore pressure through IODP drilling

    NASA Astrophysics Data System (ADS)

    Saffer, D. M.; Flemings, P. B.

    2010-12-01

    It is critical to understand the magnitude and distribution of subsurface pore fluid pressure: it controls effective stress and thus mechanical strength, slope stability, and sediment compaction. Elevated pore pressures also drive fluid flows that serve as agents of mass, solute, and heat fluxes. The Ocean Drilling Program (ODP) and Integrated Ocean Drilling Program (IODP) have provided important avenues to quantify pore pressure in a range of geologic and tectonic settings. These approaches include 1) analysis of continuous downhole logs and shipboard physical properties data to infer compaction state and in situ pressure and stress, 2) laboratory consolidation testing of core samples collected by drilling, 3) direct downhole measurements using pore pressure probes, 3) pore pressure and stress measurements using downhole tools that can be deployed in wide diameter pipe recently acquired for riser drilling, and 4) long-term monitoring of formation pore pressure in sealed boreholes within hydraulically isolated intervals. Here, we summarize key advances in quantification of subsurface pore pressure rooted in scientific drilling, highlighting with examples from subduction zones, the Gulf of Mexico, and the New Jersey continental shelf. At the Nankai, Costa Rican, and Barbados subduction zones, consolidation testing of cores samples, combined with analysis of physical properties data, indicates that even within a few km landward of the trench, pore pressures in and below plate boundary décollement zones reach a significant fraction of the lithostatic load (λ*=0.25-0.91). These results document a viable and quantifiable mechanism to explain the mechanical weakness of subduction décollements, and are corroborated by a small number of direct measurements in sealed boreholes and by inferences from seismic reflection data. Recent downhole measurements conducted during riser drilling using the modular formation dynamics tester wireline tool (MDT) in a forearc basin ~50

  12. Quantifying sediment sources in a lowland agricultural catchment pond using (137)Cs activities and radiogenic (87)Sr/(86)Sr ratios.

    PubMed

    Le Gall, Marion; Evrard, Olivier; Foucher, Anthony; Laceby, J Patrick; Salvador-Blanes, Sébastien; Thil, François; Dapoigny, Arnaud; Lefèvre, Irène; Cerdan, Olivier; Ayrault, Sophie

    2016-10-01

    Soil erosion often supplies high sediment loads to rivers, degrading water quality and contributing to the siltation of reservoirs and lowland river channels. These impacts are exacerbated in agricultural catchments where modifications in land management and agricultural practices were shown to accelerate sediment supply. In this study, sediment sources were identified with a novel tracing approach combining cesium ((137)Cs) and strontium isotopes ((87)Sr/(86)Sr) in the Louroux pond, at the outlet of a lowland cultivated catchment (24km(2), Loire River basin, France) representative of drained agricultural areas of Northwestern Europe. Surface soil (n=36) and subsurface channel bank (n=17) samples were collected to characterize potential sources. Deposited sediment (n=41) was sampled across the entire surface of the pond to examine spatial variation in sediment deposits. In addition, a 1.10m sediment core was sampled in the middle of the pond to reconstruct source variations throughout time. (137)Cs was used to discriminate between surface and subsurface sources, whereas (87)Sr/(86)Sr ratios discriminated between lithological sources. A distribution modeling approach quantified the relative contribution of these sources to the sampled sediment. Results indicate that surface sources contributed to the majority of pond (μ 82%, σ 1%) and core (μ 88%, σ 2%) sediment with elevated subsurface contributions modeled near specific sites close to the banks of the Louroux pond. Contributions of the lithological sources were well mixed in surface sediment across the pond (i.e., carbonate sediment contribution, μ 48%, σ 1% and non-carbonate sediment contribution, μ 52%, σ 3%) although there were significant variations of these source contributions modeled for the sediment core between 1955 and 2013. These fluctuations reflect both the progressive implementation of land consolidation schemes in the catchment and the eutrophication of the pond. This original sediment

  13. Quantifying sediment sources in a lowland agricultural catchment pond using (137)Cs activities and radiogenic (87)Sr/(86)Sr ratios.

    PubMed

    Le Gall, Marion; Evrard, Olivier; Foucher, Anthony; Laceby, J Patrick; Salvador-Blanes, Sébastien; Thil, François; Dapoigny, Arnaud; Lefèvre, Irène; Cerdan, Olivier; Ayrault, Sophie

    2016-10-01

    Soil erosion often supplies high sediment loads to rivers, degrading water quality and contributing to the siltation of reservoirs and lowland river channels. These impacts are exacerbated in agricultural catchments where modifications in land management and agricultural practices were shown to accelerate sediment supply. In this study, sediment sources were identified with a novel tracing approach combining cesium ((137)Cs) and strontium isotopes ((87)Sr/(86)Sr) in the Louroux pond, at the outlet of a lowland cultivated catchment (24km(2), Loire River basin, France) representative of drained agricultural areas of Northwestern Europe. Surface soil (n=36) and subsurface channel bank (n=17) samples were collected to characterize potential sources. Deposited sediment (n=41) was sampled across the entire surface of the pond to examine spatial variation in sediment deposits. In addition, a 1.10m sediment core was sampled in the middle of the pond to reconstruct source variations throughout time. (137)Cs was used to discriminate between surface and subsurface sources, whereas (87)Sr/(86)Sr ratios discriminated between lithological sources. A distribution modeling approach quantified the relative contribution of these sources to the sampled sediment. Results indicate that surface sources contributed to the majority of pond (μ 82%, σ 1%) and core (μ 88%, σ 2%) sediment with elevated subsurface contributions modeled near specific sites close to the banks of the Louroux pond. Contributions of the lithological sources were well mixed in surface sediment across the pond (i.e., carbonate sediment contribution, μ 48%, σ 1% and non-carbonate sediment contribution, μ 52%, σ 3%) although there were significant variations of these source contributions modeled for the sediment core between 1955 and 2013. These fluctuations reflect both the progressive implementation of land consolidation schemes in the catchment and the eutrophication of the pond. This original sediment

  14. Are sea otters being exposed to subsurface intertidal oil residues from the Exxon Valdez oil spill?

    PubMed

    Boehm, P D; Page, D S; Neff, J M; Brown, J S

    2011-03-01

    Twenty years after the Exxon Valdez oil spill, scattered patches of subsurface oil residues (SSOR) can still be found in intertidal sediments at a small number of shoreline locations in Prince William Sound, Alaska. Some scientists hypothesize that sea otters continue to be exposed to SSOR by direct contact when otters dig pits in search of clams. This hypothesis is examined through site-specific examinations where SSOR and otter-dug pits co-occur. Surveys documented the exact sediment characteristics and locations on the shore at the only three subdivisions where both SSOR and otter pits were found after 2000. Shoreline characteristics and tidal heights where SSOR have persisted are not suitable habitat for sea otters to dig pits during foraging. There is clear separation between areas containing SSOR and otter foraging pits. The evidence allows us to reject the hypothesis that sea otters encounter and are being exposed by direct contact to SSOR.

  15. Are sea otters being exposed to subsurface intertidal oil residues from the Exxon Valdez oil spill?

    PubMed

    Boehm, P D; Page, D S; Neff, J M; Brown, J S

    2011-03-01

    Twenty years after the Exxon Valdez oil spill, scattered patches of subsurface oil residues (SSOR) can still be found in intertidal sediments at a small number of shoreline locations in Prince William Sound, Alaska. Some scientists hypothesize that sea otters continue to be exposed to SSOR by direct contact when otters dig pits in search of clams. This hypothesis is examined through site-specific examinations where SSOR and otter-dug pits co-occur. Surveys documented the exact sediment characteristics and locations on the shore at the only three subdivisions where both SSOR and otter pits were found after 2000. Shoreline characteristics and tidal heights where SSOR have persisted are not suitable habitat for sea otters to dig pits during foraging. There is clear separation between areas containing SSOR and otter foraging pits. The evidence allows us to reject the hypothesis that sea otters encounter and are being exposed by direct contact to SSOR. PMID:21185036

  16. Spreadsheet log analysis in subsurface geology

    USGS Publications Warehouse

    Doveton, J.H.

    2000-01-01

    Most of the direct knowledge of the geology of the subsurface is gained from the examination of core and drill-cuttings recovered from boreholes drilled by the petroleum and water industries. Wireline logs run in these same boreholes generally have been restricted to tasks of lithostratigraphic correlation and thee location of hydrocarbon pay zones. However, the range of petrophysical measurements has expanded markedly in recent years, so that log traces now can be transformed to estimates of rock composition. Increasingly, logs are available in a digital format that can be read easily by a desktop computer and processed by simple spreadsheet software methods. Taken together, these developments offer accessible tools for new insights into subsurface geology that complement the traditional, but limited, sources of core and cutting observations.

  17. Desiccation-crack-induced salinization in deep clay sediment

    NASA Astrophysics Data System (ADS)

    Baram, S.; Ronen, Z.; Kurtzman, D.; Külls, C.; Dahan, O.

    2013-04-01

    A study on water infiltration and solute transport in a clayey vadose zone underlying a dairy farm waste source was conducted to assess the impact of desiccation cracks on subsurface evaporation and salinization. The study is based on five years of continuous measurements of the temporal variation in the vadose zone water content and on the chemical and isotopic composition of the sediment and pore water in it. The isotopic composition of water stable isotopes (δ18O and δ2H) in water and sediment samples, from the area where desiccation crack networks prevail, indicated subsurface evaporation down to ~ 3.5 m below land surface, and vertical and lateral preferential transport of water, following erratic preferential infiltration events. Chloride (Cl-) concentrations in the vadose zone pore water substantially increased with depth, evidence of deep subsurface evaporation and down flushing of concentrated solutions from the evaporation zones during preferential infiltration events. These observations led to development of a desiccation-crack-induced salinization (DCIS) conceptual model. DCIS suggests that thermally driven convective air flow in the desiccation cracks induces evaporation and salinization in relatively deep sections of the subsurface. This conceptual model supports previous conceptual models on vadose zone and groundwater salinization in fractured rock in arid environments and extends its validity to clayey soils in semi-arid environments.

  18. Desiccation-crack-induced salinization in deep clay sediment

    NASA Astrophysics Data System (ADS)

    Baram, S.; Ronen, Z.; Kurtzman, D.; Küells, C.; Dahan, O.

    2012-11-01

    A study on water infiltration and solute transport in a clayey vadose zone underlying a dairy farm waste source was conducted to assess the impact of desiccation cracks on subsurface evaporation and salinization. The study is based on five years of continuous measurements of the temporal variation in the vadose zone water-content and on the chemical and isotopic composition of the sediment and pore-water in it. The isotopic composition of water stable isotopes (δ18O and δ2H) in water and sediment samples, from the area where desiccation crack networks prevail, indicated subsurface evaporation down to ∼3.5 m below land surface, and vertical and lateral preferential transport of water, following erratic preferential infiltration events. Chloride (Cl-) concentrations in the vadose zone pore water substantially increased with depth, evidence of deep subsurface evaporation and down flushing of concentrated solutions from the evaporation zones during preferential infiltration events. These observations led to development of a Desiccation-Crack-Induced Salinization (DCIS) conceptual model. DCIS suggests that thermally driven convective air flow in the desiccation cracks induces evaporation and salinization in relatively deep sections of the subsurface. This conceptual model supports previous conceptual models on vadose zone and groundwater salinization in fractured rock in arid environments and extends its validity to clayey soils in semi-arid environments.

  19. CLASSIFICATION OF THE MGR SUBSURFACE EXCAVATION SYSTEM

    SciTech Connect

    R. Garrett

    1999-08-31

    The purpose of this analysis is to document the Quality Assurance (QA) classification of the Monitored Geologic Repository (MGR) subsurface excavation system structures, systems and components (SSCs) performed by the MGR Safety Assurance Department. This analysis also provides the basis for revision of YMP/90-55Q, Q-List (YMP 1998). The Q-List identifies those MGR SSCs subject to the requirements of DOE/RW-0333P, ''Quality Assurance Requirements and Description'' (QARD) (DOE 1998).

  20. CLASSIFICATION OF THE MGR SUBSURFACE VENTILATION SYSTEM

    SciTech Connect

    R.J. Garrett

    1999-08-31

    The purpose of this analysis is to document the Quality Assurance (QA) classification of the Monitored Geologic Repository (MGR) subsurface ventilation system structures, systems and components (SSCs) performed by the MGR Safety Assurance Department. This analysis also provides the basis for revision of YMP/90-55Q, Q-List (YMP 1998). The Q-List identifies those MGR SSCs subject to the requirements of DOE/RW-0333P7 ''Quality Assurance Requirements and Description'' (QARD) (DOE 1998).

  1. Drill Embedded Nanosensors For Planetary Subsurface Exploration

    NASA Technical Reports Server (NTRS)

    Li, Jing

    2014-01-01

    We have developed a carbon nanotube (CNT) sensor for water vapor detection under Martian Conditions and the miniaturized electronics can be embedded in the drill bit for collecting sensor data and transmit it to a computer wirelessly.This capability will enable the real time measurement of ice during drilling. With this real time and in-situ measurement, subsurface ice detection can be easy, fast, precise and low cost.

  2. Surface Signature of Subsurface-Intensified Vortices

    NASA Astrophysics Data System (ADS)

    Ciani, D.; Carton, X. J.; Chapron, B.; Bashmachnikov, I.

    2014-12-01

    The ocean at mesoscale (20-200 km) and submesoscale (0.5-20km) is highly populated by vortices. These recirculating structures are more energetic than the mean flow, they trap water masses from their origin areas and advect them across the ocean, with consequent impact on the 3D distribution of heat and tracers. Mesoscale and submesoscale structures characterize the ocean dynamics both at the sea surface and at intrathermocline depths (0-1500m), and are presently investigated by means of model outputs, in-situ and satellite (surface) data, the latest being the only way to get high resolution and synoptic observations at planetary scale (e.g., thermal-band observations, future altimetric observations given by the SWOT satellite mission). The scientific question arising from this context is related to the role of the ocean surface for inferring informations on mesoscale and submesoscale vortices at depth. This study has also been motivated by the recent detection of subsurface eddies east of the Arabian Peninsula (PHYSINDIEN experiment - 2011).Using analytical models in the frame of the QG theory, we could describe the theoretical altimetric signature of non-drifting and of drifting subsurface eddies. Numerical experiments, using both coupled QG-SQG and primitive equations models, allowed us to investigate the surface expression of intrathermocline eddies interacting with baroclinic currents or evolving under planetary beta-effect. The eddy characteristics (radius, depth, thickness, velocity) were varied, to represent various oceanic examples (Meddies, Swoddies, Reddies, Peddies, Leddies). Idealized simulations with the ROMS model, confirming theoretical estimates, showed that drifting subsurface-intensified vortices can induce dipolar sea level anomalies, up to 3 cm. This result, compatibly with future SWOT measurement accuracies (about 2 cm), is a first step towards systematic and synoptic detection of subsurface vortices.

  3. Subsurface materials management and containment system

    DOEpatents

    Nickelson, Reva A.; Richardson, John G.; Kosteinik, Kevin M.; Sloan, Paul A.

    2004-07-06

    Systems, components, and methods relating to subterranean containment barriers. Laterally adjacent tubular casings having male interlock structures and multiple female interlock structures defining recesses for receiving a male interlock structure are used to create subterranean barriers for containing and treating buried waste and its effluents. The multiple female interlock structures enable the barriers to be varied around subsurface objects and to form barrier sidewalls. The barrier may be used for treating and monitoring a zone of interest.

  4. Subsurface materials management and containment system

    DOEpatents

    Nickelson, Reva A.; Richardson, John G.; Kostelnik, Kevin M.; Sloan, Paul A.

    2006-10-17

    Systems, components, and methods relating to subterranean containment barriers. Laterally adjacent tubular casings having male interlock structures and multiple female interlock structures defining recesses for receiving a male interlock structure are used to create subterranean barriers for containing and treating buried waste and its effluents. The multiple female interlock structures enable the barriers to be varied around subsurface objects and to form barrier sidewalls. The barrier may be used for treating and monitoring a zone of interest.

  5. Nitrate bioreduction in redox-variable low permeability sediments

    SciTech Connect

    Yan, Sen; Liu, Yuanyuan; Liu, Chongxuan; Shi, Liang; Shang, Jianying; Shan, Huimei; Zachara, John M.; Fredrickson, Jim K.; Kennedy, David W.; Resch, Charles T.; Thompson, Christopher J.; Fansler, Sarah J.

    2015-09-09

    Denitrification is a microbial process that reduces nitrate and nitrite to nitrous oxide (N2O) or dinitrogen (N2) with a strong implication to global nitrogen cycling and climate change. This paper reports the effect of sediment redox conditions on the rate and end product of denitrification. The sediments were collected from a redox transition zone consisting of oxic and reduced layers at US Department of Energy’s Hanford Site where N2O was locally accumulated in groundwater. The results revealed that denitrification rate and end product varied significantly with initial sediment redox state. The denitrification rate was relatively faster, limited by organic carbon content and bioavailability in the oxic sediment. In contrast, the rate was much slower in the reduced sediment, limited by biomass and microbial function. A significant amount of N2O was accumulated in the reduced sediment; while in the oxic sediment, N2O was further reduced to N2. RT-PCR analysis revealed that nosZ, the gene that codes for N2O reductase, was below detection in the reduced sediment. The results implied that redox transition zones can be important sinks or sources of N2O depending on local biogeochemical and microbial conditions, and are important systems for understanding and modeling denitrification in subsurface environments.

  6. Combining multiple fallout radionuclides (137Cs, 7Be, 210Pbxs) improves our understanding of sediment source dynamics in tropical rivers

    NASA Astrophysics Data System (ADS)

    Evrard, O.; Laceby, J. P.; Huon, S.; Lefèvre, I.; Sengtaheuanghoung, O.; Ribolzi, O.

    2015-12-01

    Soil erosion has accelerated as a result of land use change, increasing the sediment supply to rivers worldwide. A thorough knowledge of sediment dynamics is required to design efficient management measures to control erosion and reduce sediment delivery from catchments. Fallout radionuclides are often used separately to provide spatial (137Cs) or temporal (7Be, 210Pbxs) information on sediment sources. In this study, we examine their combined application to simultaneously model spatial and temporal sediment source dynamics. To this end, potential sediment sources (n=84) and suspended sediment (n=16) were collected at two stations in a 12 km² catchment in Northern Laos during the first flood of the 2014 wet season. Part of the source material was directly sampled in ephemeral flow occurring on hillslopes to avoid the grain size selectivity problems that may occur during erosion and river transport processes. A distribution modelling approach quantified the relative contributions of recently eroded surface (labelled with both 7Be and 137Cs), recently eroded subsurface (depleted in both 7Be and 137Cs), re-suspended surface (depleted in 7Be and labelled with 137Cs) and re-suspended subsurface sources (enriched in 7Be and depleted in 137Cs). At an upstream sampling location, surface sources contributed the majority of sediment (55%) whereas subsurface sources dominated the supply of sediment downstream (74%). Importantly, re-suspended subsurface sources, labelled with 7Be, were a significant sediment source at the catchment outlet (60%). This approach demonstrates the utility of combining multiple radionuclides when investigating spatial and temporal sediment source dynamics in tropical catchments. In the future, sampling of source material in ephemeral flows occurring on hillslopes should be encouraged. Furthermore, the proposed approach should be tested in larger catchments to guide the implementation of efficient erosion control measures.

  7. Resonant seismic emission of subsurface objects

    SciTech Connect

    Korneev, Valeri A.

    2009-04-15

    Numerical modeling results and field data indicate that some contrasting subsurface objects (such as tunnels, caves, pipes, filled pits, and fluid-filled fractures) are capable of generating durable resonant oscillations after trapping seismic energy. These oscillations consist of surface types of circumferential waves that repeatedly propagate around the object. The resonant emission of such trapped energy occurs primarily in the form of shear body waves that can be detected by remotely placed receivers. Resonant emission reveals itself in the form of sharp resonant peaks for the late parts of the records, when all strong direct and primary reflected waves are gone. These peaks were observed in field data for a buried barrel filled with water, in 2D finite-difference modeling results, and in the exact canonical solution for a fluid-filled sphere. A computed animation for the diffraction of a plane wave upon a low-velocity elastic sphere confirms the generation of resonances by durable surface waves. Resonant emission has characteristic quasi-hyperbolic traveltime patterns on shot gathers. The inversion of these patterns can be performed in the frequency domain after muting the strong direct and primary scattered waves. Subsurface objects can be detected and imaged at a single resonance frequency without an accurate knowledge of source trigger time. The imaging of subsurface objects requires information about the shear velocity distribution in an embedding medium, which can be done interactively during inversion.

  8. New technologies for subsurface barrier wall construction

    SciTech Connect

    Mutch, R.D. Jr.; Ash, R.E. IV; Caputi, J.R.

    1996-12-31

    New technologies for subsurface barrier wall construction are entering the marketplace at an unprecedented pace. Much of this innovation centers around construction of geomembrane barrier walls but also includes advancements in self-hardening slurries and in permeation grouts, involving such diverse materials as colloidal silica gel and montan wax emulsions. These advancements come at a time when subsurface barrier walls are cautiously emerging out of the technological closet. During much of the 1980s, barrier walls of any type were regarded in some quarters as crude and antiquated. It was correspondingly predicted that remediation would be dominated by emerging treatment technologies such as bioremediation, air sparging, and surfactant flushing. Notwithstanding the considerable successes of these emerging technologies, particularly bioremediation, the fact remains that a significant percentage of Superfund, RCRA-corrective action and other waste disposal sites present hydrogeologic, chemical, and waste matrix complexities that far exceed the capabilities of current treatment-based remedial technologies. Consequently, containment-based technologies such as subsurface barrier walls and caps are being recognized once again as irreplaceable components of practical remediation programs at many complex sites.

  9. Activation of Peroxymonosulfate by Subsurface Minerals

    NASA Astrophysics Data System (ADS)

    Yu, Miao; Teel, Amy L.; Watts, Richard J.

    2016-08-01

    In situ chemical oxidation (ISCO) has become a widely used technology for the remediation of soil and groundwater. Although peroxymonosulfate is not a common oxidant source for ISCO, its chemical structure is similar to the ISCO reagents hydrogen peroxide and persulfate, suggesting that peroxymonosulfate may have the beneficial properties of each of these oxidants. Peroxymonosulfate activation in the presence of subsurface minerals was examined as a basis for ISCO, and possible reactive species (hydroxyl radical, sulfate radical, and reductants + nucleophiles) generated in the mineral-activated peroxymonosulfate systems were investigated. Rates of peroxymonosulfate decomposition and generation rates of reactive species were studied in the presence of three iron oxides, one manganese oxide, and three soil fractions. The iron oxide hematite-activated peroxymonosulfate system most effectively degraded the hydroxyl radical probe nitrobenzene. Reductants + nucleophiles were not generated in mineral-activated peroxymonosulfate systems. Use of the probe compound anisole in conjunction with scavengers demonstrated that both sulfate radical and hydroxyl radical are generated in mineral-activated peroxymonosulfate systems. In order to confirm the activation of peroxymonosulfate by subsurface minerals, one natural soil and associated two soil fractions were evaluated as peroxymonosulfate catalysts. The natural soil did not effectively promote the generation of oxidants; however, the soil organic matter was found to promote the generation of reductants + nucleophiles. The results of this research show that peroxymonosulfate has potential as an oxidant source for ISCO applications, and would be most effective in treating halogenated contaminants when soil organic matter is present in the subsurface.

  10. Subsurface urban heat islands in German cities.

    PubMed

    Menberg, Kathrin; Bayer, Peter; Zosseder, Kai; Rumohr, Sven; Blum, Philipp

    2013-01-01

    Little is known about the intensity and extension of subsurface urban heat islands (UHI), and the individual role of the driving factors has not been revealed either. In this study, we compare groundwater temperatures in shallow aquifers beneath six German cities of different size (Berlin, Munich, Cologne, Frankfurt, Karlsruhe and Darmstadt). It is revealed that hotspots of up to +20K often exist, which stem from very local heat sources, such as insufficiently insulated power plants, landfills or open geothermal systems. When visualizing the regional conditions in isotherm maps, mostly a concentric picture is found with the highest temperatures in the city centers. This reflects the long-term accumulation of thermal energy over several centuries and the interplay of various factors, particularly in heat loss from basements, elevated ground surface temperatures (GST) and subsurface infrastructure. As a primary indicator to quantify and compare large-scale UHI intensity the 10-90%-quantile range UHII(10-90) of the temperature distribution is introduced. The latter reveals, in comparison to annual atmospheric UHI intensities, an even more pronounced heating of the shallow subsurface.

  11. Subsurface barrier integrity verification using perfluorocarbon tracers

    SciTech Connect

    Sullivan, T.M.; Heiser, J.; Milian, L.; Senum, G.

    1996-12-01

    Subsurface barriers are an extremely promising remediation option to many waste management problems. Gas phase tracers include perfluorocarbon tracers (PFT`s) and chlorofluorocarbon tracers (CFC`s). Both have been applied for leak detection in subsurface systems. The focus of this report is to describe the barrier verification tests conducted using PFT`s and analysis of the data from the tests. PFT verification tests have been performed on a simulated waste pit at the Hanford Geotechnical facility and on an actual waste pit at Brookhaven National Laboratory (BNL). The objective of these tests were to demonstrate the proof-of-concept that PFT technology can be used to determine if small breaches form in the barrier and for estimating the effectiveness of the barrier in preventing migration of the gas tracer to the monitoring wells. The subsurface barrier systems created at Hanford and BNL are described. The experimental results and the analysis of the data follow. Based on the findings of this study, conclusions are offered and suggestions for future work are presented.

  12. Subsurface urban heat islands in German cities.

    PubMed

    Menberg, Kathrin; Bayer, Peter; Zosseder, Kai; Rumohr, Sven; Blum, Philipp

    2013-01-01

    Little is known about the intensity and extension of subsurface urban heat islands (UHI), and the individual role of the driving factors has not been revealed either. In this study, we compare groundwater temperatures in shallow aquifers beneath six German cities of different size (Berlin, Munich, Cologne, Frankfurt, Karlsruhe and Darmstadt). It is revealed that hotspots of up to +20K often exist, which stem from very local heat sources, such as insufficiently insulated power plants, landfills or open geothermal systems. When visualizing the regional conditions in isotherm maps, mostly a concentric picture is found with the highest temperatures in the city centers. This reflects the long-term accumulation of thermal energy over several centuries and the interplay of various factors, particularly in heat loss from basements, elevated ground surface temperatures (GST) and subsurface infrastructure. As a primary indicator to quantify and compare large-scale UHI intensity the 10-90%-quantile range UHII(10-90) of the temperature distribution is introduced. The latter reveals, in comparison to annual atmospheric UHI intensities, an even more pronounced heating of the shallow subsurface. PMID:23178772

  13. Activation of Peroxymonosulfate by Subsurface Minerals.

    PubMed

    Yu, Miao; Teel, Amy L; Watts, Richard J

    2016-08-01

    In situ chemical oxidation (ISCO) has become a widely used technology for the remediation of soil and groundwater. Although peroxymonosulfate is not a common oxidant source for ISCO, its chemical structure is similar to the ISCO reagents hydrogen peroxide and persulfate, suggesting that peroxymonosulfate may have the beneficial properties of each of these oxidants. Peroxymonosulfate activation in the presence of subsurface minerals was examined as a basis for ISCO, and possible reactive species (hydroxyl radical, sulfate radical, and reductants+nucleophiles) generated in the mineral-activated peroxymonosulfate systems were investigated. Rates of peroxymonosulfate decomposition and generation rates of reactive species were studied in the presence of three iron oxides, one manganese oxide, and three soil fractions. The iron oxide hematite-activated peroxymonosulfate system most effectively degraded the hydroxyl radical probe nitrobenzene. Reductants+nucleophiles were not generated in mineral-activated peroxymonosulfate systems. Use of the probe compound anisole in conjunction with scavengers demonstrated that both sulfate radical and hydroxyl radical are generated in mineral-activated peroxymonosulfate systems. In order to confirm the activation of peroxymonosulfate by subsurface minerals, one natural soil and associated two soil fractions were evaluated as peroxymonosulfate catalysts. The natural soil did not effectively promote the generation of oxidants; however, the soil organic matter was found to promote the generation of reductants + nucleophiles. The results of this research show that peroxymonosulfate has potential as an oxidant source for ISCO applications, and would be most effective in treating halogenated contaminants when soil organic matter is present in the subsurface.

  14. Vertical stratification of subsurface microbial community composition across geological formations at the Hanford Site

    SciTech Connect

    Lin, Xueju; Kennedy, David W.; Fredrickson, Jim K.; Bjornstad, Bruce N.; Konopka, Allan

    2012-02-01

    The microbial diversity in subsurface sediments at the Hanford Site's 300 Area in southeastern Washington State was investigated by analyzing 21 samples recovered from depths that ranged from 9 to 52 m. Approximately 8000 non-chimeric Bacterial and Archaeal 16S rRNA gene sequences were analyzed across geological strata that contain a natural redox transition zone. These strata included the oxic coarse-grained Hanford formation, fine-grained oxic and anoxic Ringold Formation sediments, and the weathered basalt group. We detected 1233 and 120 unique bacterial and archaeal OTUs (Operational Taxonomic Units, defined at the 97% identity level). Microbial community structure and richness varied substantially across the different geological strata. Bacterial OTU richness (based upon Chao1 estimator) was highest (>700) in the upper Hanford formation, and declined to about 120 at the bottom of the Hanford formation. Just above the Ringold oxic-anoxic transition zone, richness was about 325 and declined to less than 50 in the deeper reduced zones. The Bacterial community in the oxic Hanford and Ringold Formations contained members of 9 major well-recognized phyla as well 30 as unusually high proportions of 3 candidate divisions (GAL15, NC10, and SPAM). The deeper Ringold strata were characterized by low OTU richness and a very high preponderance (ca. 90%) of Proteobacteria. The study has greatly expanded the intralineage phylogenetic diversity within some major divisions. These subsurface sediments have been shown to contain a large number of phylogenetically novel microbes, with substantial heterogeneities between sediment samples from the same geological formation.

  15. Modeling of Carbon Tetrachloride Flow and Transport in the Subsurface of the 200 West Disposal Sites: Large-Scale Model Configuration and Prediction of Future Carbon Tetrachloride Distribution Beneath the 216-Z-9 Disposal Site

    SciTech Connect

    Oostrom, Mart; Thorne, Paul D.; Zhang, Z. F.; Last, George V.; Truex, Michael J.

    2008-12-17

    Three-dimensional simulations considered migration of dense, nonaqueous phase liquid (DNAPL) consisting of CT and co disposed organics in the subsurface as a function of the properties and distribution of subsurface sediments and of the properties and disposal history of the waste. Simulations of CT migration were conducted using the Water-Oil-Air mode of Subsurface Transport Over Multiple Phases (STOMP) simulator. A large-scale model was configured to model CT and waste water discharge from the major CT and waste-water disposal sites.

  16. Identifying sediment sources in a drained lowland agricultural catchment: the application of a novel thorium-based particle size correction in sediment fingerprinting

    NASA Astrophysics Data System (ADS)

    Laceby, J. P.; Le Gall, M.; Foucher, A.; Salvador-Blanes, S.; Evrard, O.; Lefèvre, I.; Cerdan, O.; Desmet, M.

    2015-12-01

    Soil erosion is one of the main processes influencing land and water degradation at the global scale. Identifying the main sediment sources is therefore essential for effective soil erosion management. Accordingly, caesium-137 (137Cs) concentrations were used to quantify the relative contribution of surface and subsurface erosion sources in a lowland drained catchment in France. As 137Cs concentrations are often dependent on particle size, specific surface area (SSA) and novel Thorium (Th) based particle size corrections were applied. Surface and subsurface samples were collected to characterize the radionuclide properties of potential sources. Sediment samples were collected during one hydrological year and a sediment core was sampled to represent sediment accumulated over a longer temporal period. Additionally, sediment from tile drains was sampled to determine the radionuclide properties of sediment exported from the drainage network. The results highlight a substantial enrichment in fine particles and associated 137Cs concentrations between the sources and the sediment. The application of both correction factors reduced this difference, with the Th correction providing a more accurate comparison of source and sediment samples than the SSA correction. Modelling results clearly indicate the dominance of surface sources during the flood events and in the sediment core. Sediment exported from the drainage network was modelled to originate predominantly from surface sources. This study demonstrates the potential of Th to correct for 137Cs particle size enrichment. More importantly, this research indicates that drainage networks may significantly increase the connectivity of surface sources to stream networks. Managing sediment transferred through drainage networks may reduce the deleterious effects of suspended sediment loads on riverine systems in similar lowland drained agricultural catchments.

  17. Influences of topography and subsurface heterogeneity on lateral subsurface flow in unsaturated zone

    NASA Astrophysics Data System (ADS)

    Kim, J.; Mohanty, B.

    2014-12-01

    Lateral subsurface flow plays a significant role in redistributing soil water which has a direct effect on biological, chemical, and geomorphologic processes in root zone. However, most of the land surface models (LSMs) are neglecting the horizontal exchanges of water at the grid or subgrid scales, focusing only on the vertical exchanges of entities including water as one-dimensional process. Topography and hydrologic properties are the main controls on the vertical and lateral subsurface flow in heterogeneous land surface. Thus, in this study, we designed three cases to consider the lateral subsurface flow in unsaturated zone using a land surface model (Community Land Model, CLM): Case 1 is to consider only surface topography for the entire soil column, Case 2 is to consider surface topography in upper soil layers and heterogeneous soil hydraulic properties between the soil columns (using uniform anisotropy for lateral hydraulic conductivity) in lower soil layers, and Case 3 is also to consider surface topography and heterogeneous soil hydraulic properties but using spatially distributed anisotropy derived from hydrologic connectivity which can be created by physical controls (e.g., soil type, vegetation cover) at a watershed scale. The results of this study indicated that all of the cases improved the subsurface flow in unsaturated zone compared to the results of original model, especially representing the best performance in the case 3. Hence, this approach could characterize the spatially distributed patterns of subsurface flow and improve a simulation of the hydrologic cycle.

  18. Role of the terrestrial subsurface in shaping geothermal spring microbial communities.

    PubMed

    Tin, Sara; Bizzoco, Richard W; Kelley, Scott T

    2011-08-01

    In this study, we explored the possibility that dispersal from terrestrial subsurface sources 'seeds' the development of geothermal spring microbial assemblages. We combined microscopy and culture-independent molecular approaches to survey the bacterial diversity of spring source waters in Yellowstone National Park, Lassen Volcanic National Park, and Russia's Kamchatka peninsula. Microscopic analysis uncovered clear evidence of microbial cells from spring sources in all three regions. Analysis of source water phylogenetic diversity identified members of all bacteria groups found previously in downstream sediments, as well as many other phylogenetic groups. Closely related or identical 16S sequences were determined from the source waters of geographically distant, chemically distinct springs, and we found no association between spring water chemistry and microbial diversity. In the source waters of two different Yellowstone springs, we also discovered a phylogenetic group of uncultured Firmicutes never before reported in geothermal habitats that were closely related to uncultured bacteria found in the hyper-arid Atacama Desert. Altogether, our results suggest geothermal features can be connected via the subsurface over long distances and that subsurface sources provide a potentially diverse source of microorganisms for downstream surface mat communities.

  19. Flat meridional temperature gradient in the early Eocene in the subsurface rather than surface ocean

    NASA Astrophysics Data System (ADS)

    Ho, Sze Ling; Laepple, Thomas

    2016-08-01

    The early Eocene (49-55 million years ago) is a time interval characterized by elevated surface temperatures and atmospheric CO2 (refs ,), and a flatter-than-present latitudinal surface temperature gradient. The multi-proxy-derived flat temperature gradient has been a challenge to reproduce in model simulations, especially the subtropical warmth at the high-latitude surface oceans, inferred from the archaeal lipid-based palaeothermometry, . Here we revisit the interpretation by analysing a global collection of multi-proxy temperature estimates from sediment cores spanning millennia to millions of years. Comparing the variability between proxy types, we demonstrate that the present interpretation overestimates the magnitude of past climate changes on all timescales. We attribute this to an inappropriate calibration, which reflects subsurface ocean but is calibrated to the sea surface, where the latitudinal temperature gradient is steeper. Recalibrating the proxy to the temperatures of subsurface ocean, where the signal is probably formed, yields colder -temperatures and latitudinal gradient consistent with standard climate model simulations of the Eocene climate, invalidating the apparent, extremely warm polar sea surface temperatures. We conclude that there is a need to reinterpret -inferred marine temperature records in the literature, especially for reconstructions of past warm climates that rely heavily on this proxy as reflecting subsurface ocean.

  20. Tertiary subsurface solution in the Mississippian Leadville Limestone geothermal aquifer of Colorado

    SciTech Connect

    Bridges, L.W.D.; McCarthy, K.

    1990-04-01

    Subsurface solution by geothermal waters during the Tertiary rather than karst formation during the Paleozoic may account for the solution features found at the top of the Mississippian Leadville Limestone. Evidence at Guernsey, Wyoming suggests overlying sediments were lithified long before solution features formed. At Treasure Mountain, Colorado, a 108 ft (33 m) interval above the fill material is also Mississippian, which may indicate nearly continuous Mississippian deposition in the axis of the Mississippian seaway. It is unlikely that a karst surface could have developed in this restricted time period. The chert breccias of Guernsey and Treasure Mountain show no evidence of abrasion. This chert appears to have been precipitated from silica dissolved by geothermal waters in Tertiary time and later fractured by slumping. Earlier workers found much debris from overlying formations in Leadville solution features, but most dismissed the possibility of late-state subsurface dissolution contemporaneous with ore deposition. The authors postulate that subsurface solution took place in Tertiary time during the heating phase associated with orogeny, mineralization, and igneous activity. Dissolution was localized by pressure differences and fluid flow near major faults associated with mineralization. The largest solution areas are associated with deep-seated faults such as the Rio Grande Rift. Moderate to intense local solution is associated with mineralization. Small-scale, local solution and alteration may be associated with topographically controlled hot spring systems.

  1. Mineral Dissolution and Secondary Precipitation on Quartz Sand in Simulated Hanford Tank Solutions Affecting Subsurface Porosity

    SciTech Connect

    Wang, Guohui; Um, Wooyong

    2012-11-23

    Highly alkaline nuclear waste solutions have been released from underground nuclear waste storage tanks and pipelines into the vadose zone at the U.S. Department of Energy’s Hanford Site in Washington, causing mineral dissolution and re-precipitation upon contact with subsurface sediments. High pH caustic NaNO3 solutions with and without dissolved Al were reacted with quartz sand through flow-through columns stepwise at 45, 51, and 89°C to simulate possible reactions between leaked nuclear waste solution and primary subsurface mineral. Upon reaction, Si was released from the dissolution of quartz sand, and nitrate-cancrinite [Na8Si6Al6O24(NO3)2] precipitated on the quartz surface as a secondary mineral phase. Both steady-state dissolution and precipitation kinetics were quantified, and quartz dissolution apparent activation energy was determined. Mineral alteration through dissolution and precipitation processes results in pore volume and structure changes in the subsurface porous media. In this study, the column porosity increased up to 40.3% in the pure dissolution column when no dissolved Al was present in the leachate, whereas up to a 26.5% porosity decrease was found in columns where both dissolution and precipitation were observed because of the presence of Al in the input solution. The porosity change was also confirmed by calculation using the dissolution and precipitation rates and mineral volume changes.

  2. Legacy Sediments in U.S. River Environments: Atrazine and Aggradation to Zinc and Zoobenthos

    NASA Astrophysics Data System (ADS)

    Wohl, E.

    2014-12-01

    Legacy sediments are those that are altered by human activities. Alterations include (i) human-caused aggradation (and subsequent erosion), such as sediment accumulating upstream from relict or contemporary dams, (ii) human-caused lack of continuing deposition that results in changing moisture and nutrient levels within existing sediments, such as on floodplains that no longer receive lateral or vertical accretion deposits because of levees, bank stabilization, and other channel engineering, and (iii) human-generated contaminants such as PCBs and pesticides that adsorb to fine sediment. Existing estimates of human alterations of river systems suggest that legacy sediments are ubiquitous. Only an estimated 2% of river miles in the United States are not affected by flow regulation that alters sediment transport, for example, and less than half of major river basins around the world are minimally altered by flow regulation. Combined with extensive but poorly documented reduction in floodplain sedimentation, as well as sediment contamination by diverse synthetic compounds, excess nutrients, and heavy metals, these national and global estimates suggest that legacy sediments now likely constitute a very abundant type of fluvial sediment. Because legacy sediments can alter river form and function for decades to centuries after the cessation of the human activity that created the legacy sediments, river management and restoration must be informed by accurate knowledge of the distribution and characteristics of legacy sediments. Geomorphologists can contribute understanding of sediment dynamics, including: the magnitude, frequency, and duration of flows that mobilize sediments with adsorbed contaminants; sites where erosion and deposition are most likely to occur under specified flow and sediment supply; residence time of sediments; and the influence of surface and subsurface water fluxes on sediment stability and geochemistry.

  3. Reactive transport benchmarks for subsurface environmental simulation

    SciTech Connect

    Steefel, Carl I.; Yabusaki, Steven B.; Mayer, K. U.

    2015-06-01

    Over the last 20 years, we have seen firsthand the evolution of multicomponent reactive transport modeling and the expanding range and increasing complexity of subsurface applications it is being used to address. There is a growing reliance on reactive transport modeling (RTM) to address some of the most compelling issues facing our planet: climate change, nuclear waste management, contaminant remediation, and pollution prevention. While these issues are motivating the development of new and improved capabilities for subsurface environmental modeling using RTM (e.g., biogeochemistry from cell-scale physiology to continental-scale terrestrial ecosystems, nonisothermal multiphase conditions, coupled geomechanics), there remain longstanding challenges in characterizing the natural variability of hydrological, biological, and geochemical properties in subsurface environments and limited success in transferring models between sites and across scales. An equally important trend over the last 20 years is the evolution of modeling from a service sought out after data has been collected to a multifaceted research approach that provides (1) an organizing principle for characterization and monitoring activities; (2) a systematic framework for identifying knowledge gaps, developing and integrating new knowledge; and (3) a mechanistic understanding that represents the collective wisdom of the participating scientists and engineers. There are now large multidisciplinary projects where the research approach is model-driven, and the principal product is a holistic predictive simulation capability that can be used as a test bed for alternative conceptualizations of processes, properties, and conditions. Much of the future growth and expanded role for RTM will depend on its continued ability to exploit technological advancements in the earth and environmental sciences. Advances in measurement technology, particularly in molecular biology (genomics), isotope fractionation, and high

  4. Subsurface geology of Medina Group (Lower Silurian) and Clinton Group (Lower to Upper Silurian) of New York

    SciTech Connect

    Kearney, M.W.

    1984-12-01

    The depositional environments and geologic history of the Medina Group (Lower Silurian) and the Clinton Group (Lower to Upper Silurian) of New York have been interpreted from a regional subsurface study using approximately 250 ..gamma..-ray logs and 125 sample logs. A sequence of paleogeographic maps illustrate the geologic history and depositional environments associated with this predominantly clastic, rock sequence. Seven principle depositional environments are recognized on the basis of subsurface sedimentary facies. The Silurian clastic rocks were deposited during an overall marine transgression that was interrupted by three major progradational phases. The orogenic episodes represented by these progradational phases steadily decreased in intensity. The sediment influx during the first progradational phase was large enough to produce a deltaic system that extended throughout New York. During the second progradational phase, the sediment influx was small relative to the first event, and subsidence probably increased from loading of the Grimsby sediments. The deltaic system that developed during this time was restricted to east-central New York. The final progradational phase represents an even smaller influx of terrigenous material; only a linear clastic shoreline developed in eastern New York. This phase marks the last major influx of terrigenous clastic sediments until Devonian time.

  5. Effects of Surface and Subsurface Bed Material Composition on Gravel Transport and Flow Competence Relations—Possibilities for Prediction

    NASA Astrophysics Data System (ADS)

    Bunte, K.; Abt, S. R.; Swingle, K. W.; Cenderelli, D. A.; Gaeuman, D. A.

    2014-12-01

    Bedload transport and flow competence relations are difficult to predict in coarse-bedded steep streams where widely differing sediment supply, bed stability, and complex flow hydraulics greatly affect amounts and sizes of transported gravel particles. This study explains how properties of bed material surface and subsurface size distributions are directly related to gravel transport and may be used for prediction of gravel transport and flow competence relations. Gravel transport, flow competence, and bed material size were measured in step-pool and plane-bed streams. Power functions were fitted to gravel transport QB=aQb and flow competence Dmax=cQd relations; Q is water discharge. Frequency distributions of surface FDsurf and subsurface FDsub bed material were likewise described by power functions FDsurf=hD j and FDsub=kDm fitted over six 0.5-phi size classes within 4 to 22.4 mm. Those gravel sizes are typically mobile even in moderate floods. Study results show that steeper subsurface bed material size distributions lead to steeper gravel transport and flow competence relations, whereas larger amounts of sediment contained in those 6 size bedmaterial classes (larger h and k) flatten the relations. Similarly, steeper surface size distributions decrease the coefficients of the gravel transport and flow competence relations, whereas larger amounts of sediment within the six bed material classes increase the intercepts of gravel transport and flow competence relations. Those relations are likely causative in streams where bedload stems almost entirely from the channel bed as opposed to direct (unworked) contributions from hillslopes and tributaries. The exponent of the subsurface bed material distribution m predicted the gravel transport exponent b with r2 near 0.7 and flow competence exponent d with r2 near 0.5. The intercept of bed surface distributions h increased the intercept a of gravel transport and c of the flow competence relations with r2 near 0.6.

  6. Quantification of microbial activity in subsurface environments using a hydrogenase enzyme assay

    NASA Astrophysics Data System (ADS)

    Adhikari, R. R.; Nickel, J.; Kallmeyer, J.

    2012-04-01

    The subsurface biosphere is the largest microbial ecosystem on Earth. Despite its large size and extensive industrial exploitation, very little is known about the role of microbial activity in the subsurface. Subsurface microbial activity plays a fundamental role in geochemical cycles of carbon and other biologically important elements. How the indigenous microbial communities are supplied with energy is one of the most fundamental questions in subsurface research. It is still an enigma how these communities can survive with such recalcitrant carbon over geological time scales. Despite its usually very low concentration, hydrogen is an important element in subsurface environments. Heterotrophic and chemoautotrophic microorganisms use hydrogen in their metabolic pathways; they either obtain protons from the radiolysis of water and/or cleavage of hydrogen generated by the alteration of basaltic crust, or they dispose of protons by formation of water. Hydrogenase (H2ase) is a ubiquitous intracellular enzyme that catalyzes the interconversion of molecular hydrogen and/or water into protons and electrons. The protons are used for the synthesis of ATP, thereby coupling energy-generating metabolic processes to electron acceptors such as carbon dioxide or sulfate. H2ase activity can therefore be used as a measure for total microbial activity as it targets a key metabolic compound rather than a specific turnover process. Using a highly sensitive tritium assay we measured H2ase enzyme activity in the organic-rich sediments of Lake Van, a saline, alkaline lake in eastern Turkey and in marine subsurface sediments of the Barents Sea. Additionally, sulfate reduction rates (SRRs) were measured to compare the results of the H2ase enzyme assay with the quantitatively most important electron acceptor process. H2ase activity was found at all sites, measured values and distribution of activity varied widely with depth and between sites. At the Lake Van sites H2ase activity ranged from

  7. The Influence of Sediment Size on Dissolved Inorganic Nitrogen in Hyporheic Mesocosms

    NASA Astrophysics Data System (ADS)

    Harvey, B. N.; Johnson, M. L.; Kiernan, J. D.; Green, P. G.

    2007-12-01

    Dissolved inorganic nitrogen (DIN) is composed of nitrate, nitrite and ammonia. The availability of DIN in streams is important to water quality and to stream ecosystems in general because at low concentrations DIN can limit primary productivity, while at high concentrations DIN contributes to eutrophication. An important location of nitrogen transformations in streams is the interstitial spaces between streambed sediments. As surface water passes transiently along shallow subsurface flow paths, the activities of interstitial biofilms and invertebrates alter the form and availability of nitrogen. Heterotrophic consumers release nitrogen as ammonia. Nitrifying bacteria further transform ammonia to nitrate under aerobic conditions. While under anaerobic conditions denitrifying bacteria can transform nitrate to nitrogen gas. Studies in natural streambeds have suggested the size of streambed sediments can influence whether the streambed serves as a net source or sink for DIN in transient sub-surface water. We tested whether the size distribution of streambed sediments in isolation from the effects of streambed topography and groundwater upwelling could alter DIN production or uptake as stream water passed transiently along interstitial flow paths. We filled pipes with contrasting sediment mixes, and placed them in a stream so that surface water flowed through the sediments. After an incubation period allowing biofilm development, we measured nitrate + nitrite and ammonia in interstitial water drawn at several distances along the pipes. These measurements revealed that both sediment types were net sources of DIN, with the majority of DIN production occurring near the beginning of subsurface flow paths. Concentrations of DIN were greater in the finer sediments at any given distance along the pipes. However, higher surface water exchange rates through the coarser sediments caused net DIN production in the coarse sediments, and therefore DIN release to surface water, to

  8. Lower Silurian-Upper Ordovician subsurface glacial outwash deposits, northern Saudi Arabia

    SciTech Connect

    Dobson, P.B. )

    1991-08-01

    Recently acquired seismic data reinterpreted well information in northwest Saudi Arabia extends outcropping Lower Silurian to Upper Ordovician Zarqa/Sarah glacial and periglacial deposits into the subsurface. These deposits range from northeast-trending outwash-filled channels deeply incised into the underlying Ordovician Qasim and the Cambrian-Ordovician Saq Formation in the east. A southwest source for these sediments is implied by this new data. This supports previously interpreted source directions mapped from outcrop. It also correlates with the position of the Arabian plate relative to known Gonwanaland ice caps during the Early Silurian-Late Ordovician. The recognition of glacial outwash sediments in the subsurface provides new insight into the continuity and environments of deposition of the Qasim Formation members in northwest Saudi Arabia. The hydrocarbon-prone Lower Silurian Qusaiba Member of the Qalibah Formation overlies the Zarqa/Sarah Formations. The Qusaiba represents a rapid transgression of the Paleo-Tethys Sea during the final melting of the Gondwanaland ice caps. The seal-source characteristics of the Qusaiba Member, combined with the good porosity and permeability of the underlying outwash deposits, suggest a prospective hydrocarbon exploration play. Gas is produced from this reservoir in the Risha field of eastern Jordan.

  9. Physical and chemical controls on habitats for life in the deep subsurface beneath continents and ice

    PubMed Central

    Parnell, John; McMahon, Sean

    2016-01-01

    The distribution of life in the continental subsurface is likely controlled by a range of physical and chemical factors. The fundamental requirements are for space to live, carbon for biomass and energy for metabolic activity. These are inter-related, such that adequate permeability is required to maintain a supply of nutrients, and facies interfaces invite colonization by juxtaposing porous habitats with nutrient-rich mudrocks. Viable communities extend to several kilometres depth, diminishing downwards with decreasing porosity. Carbon is contributed by recycling of organic matter originally fixed by photosynthesis, and chemoautotrophy using crustal carbon dioxide and methane. In the shallow crust, the recycled component predominates, as processed kerogen or hydrocarbons, but abiotic carbon sources may be significant in deeper, metamorphosed crust. Hydrogen to fuel chemosynthesis is available from radiolysis, mechanical deformation and mineral alteration. Activity in the subcontinental deep biosphere can be traced through the geological record back to the Precambrian. Before the colonization of the Earth's surface by land plants, a geologically recent event, subsurface life probably dominated the planet's biomass. In regions of thick ice sheets the base of the ice sheet, where liquid water is stable and a sediment layer is created by glacial erosion, can be regarded as a deep biosphere habitat. This environment may be rich in dissolved organic carbon and nutrients accumulated from dissolving ice, and from weathering of the bedrock and the sediment layer. PMID:26667907

  10. Geophysical Monitoring of Coupled Microbial and Geochemical Processes During Stimulated Subsurface Bioremediation

    SciTech Connect

    Williams, Kenneth H.; Kemna, Andreas; Wilkins, Michael J.; Druhan, Jennifer L.; Arntzen, Evan V.; N'Guessan, A. Lucie; Long, Philip E.; Hubbard, Susan S.; Banfield, Jillian F.

    2009-08-05

    Understanding how microorganisms alter their physical and chemical environment during bioremediation is hindered by our inability to resolve subsurface microbial activity with high spatial resolution. Here we demonstrate the use of a minimally invasive geophysical technique to monitor stimulated microbial activity during acetate amendment in an aquifer near Rifle, Colorado. During electrical induced polarization (IP) measurements, spatiotemporal variations in the phase response between imposed electric current and the resultant electric field correlated with changes in groundwater geochemistry accompanying stimulated iron and sulfate reduction and sulfide mineral precipitation. The magnitude of the phase response varied with measurement frequency (0.125 and 1 Hz) andwasdependent upon the dominant metabolic process. The spectral effect was corroborated using a biostimulated column experiment containing Rifle sediments and groundwater. Fluids and sediments recovered from regions exhibiting an anomalous phase response were enriched in Fe(II), dissolved sulfide, and cell-associated FeS nanoparticles. The accumulation of mineral precipitates and electroactive ions altered the ability of pore fluids to conduct electrical charge, accounting for the anomalous IP response and revealing the usefulness of multifrequency IP measurements for monitoring mineralogical and geochemical changes accompanying stimulated subsurface bioremediation.

  11. Physical and chemical controls on habitats for life in the deep subsurface beneath continents and ice.

    PubMed

    Parnell, John; McMahon, Sean

    2016-01-28

    The distribution of life in the continental subsurface is likely controlled by a range of physical and chemical factors. The fundamental requirements are for space to live, carbon for biomass and energy for metabolic activity. These are inter-related, such that adequate permeability is required to maintain a supply of nutrients, and facies interfaces invite colonization by juxtaposing porous habitats with nutrient-rich mudrocks. Viable communities extend to several kilometres depth, diminishing downwards with decreasing porosity. Carbon is contributed by recycling of organic matter originally fixed by photosynthesis, and chemoautotrophy using crustal carbon dioxide and methane. In the shallow crust, the recycled component predominates, as processed kerogen or hydrocarbons, but abiotic carbon sources may be significant in deeper, metamorphosed crust. Hydrogen to fuel chemosynthesis is available from radiolysis, mechanical deformation and mineral alteration. Activity in the subcontinental deep biosphere can be traced through the geological record back to the Precambrian. Before the colonization of the Earth's surface by land plants, a geologically recent event, subsurface life probably dominated the planet's biomass. In regions of thick ice sheets the base of the ice sheet, where liquid water is stable and a sediment layer is created by glacial erosion, can be regarded as a deep biosphere habitat. This environment may be rich in dissolved organic carbon and nutrients accumulated from dissolving ice, and from weathering of the bedrock and the sediment layer. PMID:26667907

  12. Channel initiation by surface and subsurface flows in a steep catchment of the Akaishi Mountains, Japan

    NASA Astrophysics Data System (ADS)

    Imaizumi, Fumitoshi; Hattanji, Tsuyoshi; Hayakawa, Yuichi S.

    2010-02-01

    Channel initiation, which is a key factor in the evolution of mountain landforms, is caused by a combination of various hydrogeomorphic processes. We modeled the channel initiation in steep mountains on the basis of the physical mechanism for sediment transport by surface and subsurface flows. Field investigations and Geographic Information Systems (GIS) analysis in the Higashi-gouchi catchment of central Japan showed that our model can well explain the area-slope relationship in steep and highly incised subcatchments, in which surface flow and shallow underground water would be the dominant flow components. In contrast, the area-slope relationship is not clear in gentler subcatchments, in which the contribution of deeper flow components (i.e., deep underground water) on the entire runoff is not negligible. Thus, the contribution of each runoff component to the total runoff is an important factor affecting the location of the channel head. Most channel heads in the deeply incised subcatchments in the Higashi-gouchi catchment have been formed by surface and subsurface flows, although many landslides have also occurred around the channel heads. Compared with the dominant flow components, activity of sediment supply from hillslopes might be a minor factor in determining the area-slope relationship for locating the channel head.

  13. Physical and chemical controls on habitats for life in the deep subsurface beneath continents and ice.

    PubMed

    Parnell, John; McMahon, Sean

    2016-01-28

    The distribution of life in the continental subsurface is likely controlled by a range of physical and chemical factors. The fundamental requirements are for space to live, carbon for biomass and energy for metabolic activity. These are inter-related, such that adequate permeability is required to maintain a supply of nutrients, and facies interfaces invite colonization by juxtaposing porous habitats with nutrient-rich mudrocks. Viable communities extend to several kilometres depth, diminishing downwards with decreasing porosity. Carbon is contributed by recycling of organic matter originally fixed by photosynthesis, and chemoautotrophy using crustal carbon dioxide and methane. In the shallow crust, the recycled component predominates, as processed kerogen or hydrocarbons, but abiotic carbon sources may be significant in deeper, metamorphosed crust. Hydrogen to fuel chemosynthesis is available from radiolysis, mechanical deformation and mineral alteration. Activity in the subcontinental deep biosphere can be traced through the geological record back to the Precambrian. Before the colonization of the Earth's surface by land plants, a geologically recent event, subsurface life probably dominated the planet's biomass. In regions of thick ice sheets the base of the ice sheet, where liquid water is stable and a sediment layer is created by glacial erosion, can be regarded as a deep biosphere habitat. This environment may be rich in dissolved organic carbon and nutrients accumulated from dissolving ice, and from weathering of the bedrock and the sediment layer.

  14. Submarine cementation of subsurface Pliocene carbonates from the interior of Great Bahama Bank

    SciTech Connect

    Beach, D.K.

    1993-11-01

    Thick intervals of early Pliocene subtidal carbonate sediments in the subsurface of northwestern Great Bahama Bank were lithified by submarine cement. This cementation, subsequently altered by meteoric diagenesis, occurred over a broad expanse of the platform interior. It shows that submarine cements can lithify thick packstone and grainstone intervals in the interior of large shallow-water carbonate shelves and platforms given open circulation, moderate to slow sedimentation rates, and minimal accumulation of fine sediments. A submarine origin for these cements is inferred from direct and circumstantial evidence, including: (1) regional depositional and diagenetic setting; (2) fabric and habit similar to modern submarine cements; (3) alteration of cements from mineralogically unstable precursors indicated by (a) abundant inclusions, (b) relict precursor fabric, and commonly (c) yellowish coloration, (d) undulose crystal extinction, and (e) selective leaching of specific generations of cement or cement types; (4) sutured mid-pore crystal contacts; (5) precipitation coeval with accumulation of internal marine sediment; (6) association with organisms requiring a firm substrate for attachment. These considerations may help other workers recognize submarine cements in ancient carbonate rocks.

  15. Physiologically anaerobic microorganisms of the deep subsurface. Final performance report, June 1, 1990--August 31, 1993

    SciTech Connect

    Stevens, S.E. Jr.; Chung, K.T.

    1993-10-01

    Anaerobic bacteria were isolated from deep subsurface sediment samples taken at study sites in Idaho (INEL) and Washington (HR) by culturing on dilute and concentrated medium. Morphologically distinct colonies were purified, and their responses to 21 selected physiological tests were determined. Although the number of isolates was small (18 INEL, 27 HR) some general patterns could be determined. Most strains could utilize all the carbon sources, however the glycerol and melizitose utilization was positive for 50% or less of the HR isolates. Catalase activity (27.78% at INEL, 74.07% at HR) and tryptophan metabolism (11.12% at INEL, 40.74% at HR) were significantly different between the two study sites. MPN and viable counts indicate that sediments near the water table yield the greatest numbers of anaerobes. Deeper sediments also appear to be more selective with the greatest number of viable counts on low-nutrient mediums. Likewise, only strictly obligate anaerobes were found in the deepest sediment samples. Selective media indicated the presence of methanogens, acetogens, and sulfate reducers at only the HR site.

  16. Deglacial Subsurface Temperature Change in the Tropical North Atlantic Linked to Atlantic Meridional Overturning Circulation Variability

    NASA Astrophysics Data System (ADS)

    Schmidt, M. W.; Hertzberg, J. E.; Them, T. R.; Parker, A. O.; Chang, P.

    2011-12-01

    Coupled ocean-atmosphere modeling experiments conducted under both the present and Last Glacial Maximum (LGM) conditions indicate that Atlantic meridional overturning circulation (AMOC) variability is tightly coupled to abrupt tropical North Atlantic (TNA) climate change through both atmospheric and oceanic processes (Zhang, 2007; Chang et al., 2008; Chiang et al., 2008; Otto-Bliesner and Brady, 2009). While a slowdown of AMOC in these experiments results in an atmospheric-induced surface cooling in the entire TNA, the subsurface experiences an even larger warming due to rapid reorganizations of ocean circulation patterns (Wan et al., 2009). To test the hypothesis that subsurface temperature change in the TNA is coupled to AMOC variability across abrupt climate events over the last deglacial, we reconstruct Mg/Ca-temperature and δ18O records from both surface (Globigerinoides ruber, upper mixed layer) and sub-thermocline dwelling (Globorotalia truncatulinoides, 350-500 m depth) planktonic foraminifera, as well as from the benthic species Cibicidoides pachyderma in the southern Caribbean Sea sediment core VM12-107 (11.33 °N, 66.63 °W; 1079 m; 18 cm/kyr sedimentation rate). Reconstructed sea surface temperatures (SSTs) indicate a gradual warming in the TNA starting at ~19 kyr BP with small cold reversals of ~1.5 °C during Heinrich Event 1 (H1) and the Younger Dryas (YD). In contrast, LGM subsurface temperatures were as much as 2.5 °C warmer than Late Holocene values and H1 and the YD are marked by the warmest subsurface temperatures characterized by abrupt temperature increases as large as 4-5 °C. In addition, benthic Mg/Ca ratios during the YD and H1 increase by 50% relative to Holocene intervals, suggesting significant warming extending to 1079 m water depth across these events. Comparison of our subsurface temperature records with the Bermuda Rise 231Pa/230Th proxy record of AMOC variability (McManus et al., 2004) indicates a strong correlation between

  17. Iberian Pyrite Belt Subsurface Life (IPBSL): searching for life in the Rio Tinto subsurface

    NASA Astrophysics Data System (ADS)

    Amils, R.; Gómez, F.; Prieto-Ballesteros, O.; Fernández-Remolar, D.; Parro, V.; Rodríguez-Manfredi, J. A.; Tornos-Arroyo, F.; Timmis, K.; Oggerin, M.; Sánchez-Román, M.; López, F. J.; Fernández, J. P.; Omoregie, E.; Puente-Sánchez, F.; García, M.; Rodríguez, N.

    2013-09-01

    The geomicrobiologica l characterization of Río Tinto (Iberian Pyrite Belt), has proven the importance of the iron and sulfur cycles in generating the extreme conditions of acidity and high concentration of heavy metals of the habitat. It has been hypothesized that the extreme conditions found in the Tinto basin are the product of the subsurface chemolithotrophic metabolism of microorganisms thriving on the high concentrat ion of metal sulfides of the IPB. To test this hypothesis, a drilling project (IPBSL) is currently under development to provide evidence of subsurface microbial activities and the potential resources to support them.

  18. Temperature and pressure adaptation of a sulfate reducer from the deep subsurface.

    PubMed

    Fichtel, Katja; Logemann, Jörn; Fichtel, Jörg; Rullkötter, Jürgen; Cypionka, Heribert; Engelen, Bert

    2015-01-01

    Microbial life in deep marine subsurface faces increasing temperatures and hydrostatic pressure with depth. In this study, we have examined growth characteristics and temperature-related adaptation of the Desulfovibrio indonesiensis strain P23 to the in situ pressure of 30 MPa. The strain originates from the deep subsurface of the eastern flank of the Juan de Fuca Ridge (IODP Site U1301). The organism was isolated at 20°C and atmospheric pressure from ~61°C-warm sediments approximately 5 m above the sediment-basement interface. In comparison to standard laboratory conditions (20°C and 0.1 MPa), faster growth was recorded when incubated at in situ pressure and high temperature (45°C), while cell filamentation was induced by further compression. The maximum growth temperature shifted from 48°C at atmospheric pressure to 50°C under high-pressure conditions. Complementary cellular lipid analyses revealed a two-step response of membrane viscosity to increasing temperature with an exchange of unsaturated by saturated fatty acids and subsequent change from branched to unbranched alkyl moieties. While temperature had a stronger effect on the degree of fatty acid saturation and restructuring of main phospholipids, pressure mainly affected branching and length of side chains. The simultaneous decrease of temperature and pressure to ambient laboratory conditions allowed the cultivation of our moderately thermophilic strain. This may in turn be one key to a successful isolation of microorganisms from the deep subsurface adapted to high temperature and pressure. PMID:26500624

  19. Temperature and pressure adaptation of a sulfate reducer from the deep subsurface.

    PubMed

    Fichtel, Katja; Logemann, Jörn; Fichtel, Jörg; Rullkötter, Jürgen; Cypionka, Heribert; Engelen, Bert

    2015-01-01

    Microbial life in deep marine subsurface faces increasing temperatures and hydrostatic pressure with depth. In this study, we have examined growth characteristics and temperature-related adaptation of the Desulfovibrio indonesiensis strain P23 to the in situ pressure of 30 MPa. The strain originates from the deep subsurface of the eastern flank of the Juan de Fuca Ridge (IODP Site U1301). The organism was isolated at 20°C and atmospheric pressure from ~61°C-warm sediments approximately 5 m above the sediment-basement interface. In comparison to standard laboratory conditions (20°C and 0.1 MPa), faster growth was recorded when incubated at in situ pressure and high temperature (45°C), while cell filamentation was induced by further compression. The maximum growth temperature shifted from 48°C at atmospheric pressure to 50°C under high-pressure conditions. Complementary cellular lipid analyses revealed a two-step response of membrane viscosity to increasing temperature with an exchange of unsaturated by saturated fatty acids and subsequent change from branched to unbranched alkyl moieties. While temperature had a stronger effect on the degree of fatty acid saturation and restructuring of main phospholipids, pressure mainly affected branching and length of side chains. The simultaneous decrease of temperature and pressure to ambient laboratory conditions allowed the cultivation of our moderately thermophilic strain. This may in turn be one key to a successful isolation of microorganisms from the deep subsurface adapted to high temperature and pressure.

  20. Denitrifying bacteria from the terrestrial subsurface exposed to mixed waste contamination

    SciTech Connect

    Green, Stefan; Prakash, Om; Gihring, Thomas; Akob, Denise M.; Jasrotia, Puja; Jardine, Philip M; Watson, David B; Brown, Steven D; Palumbo, Anthony Vito; Kostka, Joel

    2010-01-01

    In terrestrial subsurface environments where nitrate is a critical groundwater contaminant, few cultivated representatives are available with which to verify the metabolism of organisms that catalyze denitrification. In this study, five species of denitrifying bacteria from three phyla were isolated from subsurface sediments exposed to metal radionuclide and nitrate contamination as part of the U.S. Department of Energy s Oak Ridge Integrated Field Research Challenge (OR-IFRC). Isolates belonged to the genera Afipia and Hyphomicrobium (Alphaproteobacteria), Rhodanobacter (Gammaproteobacteria), Intrasporangium (Actinobacteria) and Bacillus (Firmicutes). Isolates from the phylum Proteobacteria were confirmed as complete denitrifiers, whereas the Gram-positive isolates reduced nitrate to nitrous oxide. Ribosomal RNA gene analyses reveal that bacteria from the genus Rhodanobacter comprise a diverse population of circumneutral to moderately acidophilic denitrifiers at the ORIFRC site, with a high relative abundance in areas of the acidic source zone. Rhodanobacter species do not contain a periplasmic nitrite reductase and have not been previously detected in functional gene surveys of denitrifying bacteria at the OR-IFRC site. Sequences of nitrite and nitrous oxide reductase genes were recovered from the isolates and from the terrestrial subsurface by designing primer sets mined from genomic and metagenomic data and from draft genomes of two of the isolates. We demonstrate that a combination of cultivation, genomic and metagenomic data are essential to the in situ characterization of denitrifiers and that current PCR-based approaches are not suitable for deep coverage of denitrifying microorganisms. Our results indicate that the diversity of denitrifiers is significantly underestimated in the terrestrial subsurface.

  1. Development of in-aquifer heat testing for high resolution subsurface thermal-storage capability characterisation

    NASA Astrophysics Data System (ADS)

    Seibertz, Klodwig Suibert Oskar; Chirila, Marian Andrei; Bumberger, Jan; Dietrich, Peter; Vienken, Thomas

    2016-03-01

    The ongoing transition from fossil fuels to alternative energy source provision has resulted in increased geothermal uses as well as storage of the shallow subsurface. Existing approaches for exploration of shallow subsurface geothermal energy storage often lack the ability to provide information concerning the spatial variability of thermal storage parameters. However, parameter distributions have to be known to ensure that sustainable geothermal use of the shallow subsurface can take place - especially when it is subject to intensive usage. In this paper, we test a temperature decay time approach to obtain in situ, direct, qualitative, spatial high-resolution information about the distribution of thermal storage capabilities of the shallow subsurface. To achieve this, temperature data from a high-resolution Fibre-Optic-Distributed-Temperature-Sensing device, as well as data from conventional Pt100-temperature-sensors were collected during a heat injection test. The latter test was used to measure the decay time of temperature signal dissipation of the subsurface. Signal generation was provided by in-aquifer heating with a temperature self-regulating electric heating cable. Heating was carried out for 4.5 days. After this, a cooling period of 1.5 weeks was observed. Temperature dissipation data was also compared to Direct-Push-derived high-resolution (hydro-)geological data. The results show that besides hydraulic properties also the bedding and compaction state of the sediment have an impact on the thermal storage capability of the saturated subsurface. The temperature decay time approach is therefore a reliable method for obtaining information regarding the qualitative heat storage capability of heterogeneous aquifers for the use with closed loop system geothermal storage systems. Furthermore, this approach is advantageous over other commonly used methods, e.g. soil-sampling and laboratory analysis, as even small changes in (hydro-)geological properties lead to

  2. Noble gas fractionation during subsurface gas migration

    NASA Astrophysics Data System (ADS)

    Sathaye, Kiran J.; Larson, Toti E.; Hesse, Marc A.

    2016-09-01

    Environmental monitoring of shale gas production and geological carbon dioxide (CO2) storage requires identification of subsurface gas sources. Noble gases provide a powerful tool to distinguish different sources if the modifications of the gas composition during transport can be accounted for. Despite the recognition of compositional changes due to gas migration in the subsurface, the interpretation of geochemical data relies largely on zero-dimensional mixing and fractionation models. Here we present two-phase flow column experiments that demonstrate these changes. Water containing a dissolved noble gas is displaced by gas comprised of CO2 and argon. We observe a characteristic pattern of initial co-enrichment of noble gases from both phases in banks at the gas front, followed by a depletion of the dissolved noble gas. The enrichment of the co-injected noble gas is due to the dissolution of the more soluble major gas component, while the enrichment of the dissolved noble gas is due to stripping from the groundwater. These processes amount to chromatographic separations that occur during two-phase flow and can be predicted by the theory of gas injection. This theory provides a mechanistic basis for noble gas fractionation during gas migration and improves our ability to identify subsurface gas sources after post-genetic modification. Finally, we show that compositional changes due to two-phase flow can qualitatively explain the spatial compositional trends observed within the Bravo Dome natural CO2 reservoir and some regional compositional trends observed in drinking water wells overlying the Marcellus and Barnett shale regions. In both cases, only the migration of a gas with constant source composition is required, rather than multi-stage mixing and fractionation models previously proposed.

  3. Shallow Subsurface Structures of Volcanic Fissures

    NASA Astrophysics Data System (ADS)

    Parcheta, C. E.; Nash, J.; Mitchell, K. L.; Parness, A.

    2015-12-01

    Volcanic fissure vents are a difficult geologic feature to quantify. They are often too thin to document in detail with seismology or remote geophysical methods. Additionally, lava flows, lava drain back, or collapsed rampart blocks typically conceal a fissure's surface expression. For exposed fissures, quantifying the surface (let along sub0surface) geometric expression can become an overwhelming and time-consuming task given the non-uniform distribution of wall irregularities, drain back textures, and the larger scale sinuosity of the whole fissure system. We developed (and previously presented) VolcanoBot to acquire robust characteristic data of fissure geometries by going inside accessible fissures after an eruption ends and the fissure cools off to <50 C. Data from VolcanoBot documents the fissure conduit geometry with a near-IR structured light sensor, and reproduces the 3d structures to cm-scale accuracy. Here we present a comparison of shallow subsurface structures (<30 m depth) within the Mauna Ulu fissure system and their counterpart features at the vent-to-ground-surface interface. While we have not mapped enough length of the fissure to document sinuosity at depth, we see a self-similar pattern of irregularities on the fissure walls throughout the entire shallow subsurface, implying a fracture mechanical origin similar to faults. These irregularities are, on average, 1 m across and protrude 30 cm into the drained fissure. This is significantly larger than the 10% wall roughness addressed in the engineering literature on fluid dynamics, and implies that magma fluid dynamics during fissure eruptions are probably not as passive nor as simple as previously thought. In some locations, it is possible to match piercing points across the fissure walls, where the dike broke the wall rock in order to propagate upwards, yet in other locations there are erosional cavities, again, implying complex fluid dynamics in the shallow sub-surface during fissure eruptions.

  4. Tree Distributions, Subsurface Characteristics and Nitrogen Cycling

    NASA Astrophysics Data System (ADS)

    Brunner, L.; Wallace, M. C.; Brush, G.

    2014-12-01

    This study examines the connection between vegetation and geologic, soil and hydrologic subsurface characteristics of a natural deciduous forest in Oregon Ridge Park, located in the Piedmont physiographic province in Maryland, USA. A preliminary study showed the relationship between nitrogen cycling and four different species occurring on a coarse grained schist and a fine grained schist. Mineralization values for Liriodendon tulipifera were positive on the coarser grained substrate and negative on the fine grained substrate. Nitrification values were positive on both substrates. Mineralization and nitrification values were both positive for Quercus prinus on both the coarse and fine substrates. Mineralization values for Acer rubrum were negative on the coarse substrate and positive on the finer substrate, while mineralization for Quercus rubra was negative on the coarse substrate and positive on the fine schist. Nitrification was positive for Q. rubra on the coarse schist and both positive and negative on the fine schist. Resistivity analyses were performed in collaboration with the Wyoming Center for Environmental Hydrology and Geophysics (WyCEHG) along two perpendicular transects at the study site. This analysis provides indirect information on subsurface conductivity, with low resistivity being interpreted as subsurface water or clay. One transect crossed a valley with a first-order stream in the center, while the second transect was taken along the break and slope of the hillslope. All trees were identified and diameter at breast height (DBH) measured in sixty-three randomly located plots along both transects. A principle components analysis of all tree data showed four associations of species. The plots were labelled as to association. The position of the associations along the transects show a relationship between wet, dry and mesic associations with differences in transect resistivity.

  5. Single cell genomics of subsurface microorganisms

    NASA Astrophysics Data System (ADS)

    Stepanauskas, R.; Onstott, T. C.; Lau, C.; Kieft, T. L.; Woyke, T.; Rinke, C.; Sczyrba, A.; van Heerden, E.

    2012-12-01

    Recent studies have revealed unexpected abundance and diversity of microorganisms in terrestrial and marine subsurface, providing new perspectives over their biogeochemical significance, evolution, and the limits of life. The now commonly used research tools, such as metagenomics and PCR-based gene surveys enabled cultivation-unbiased analysis of genes encoded by natural microbial communities. However, these methods seldom provide direct evidence for how the discovered genes are organized inside genomes and from which organisms do they come from. Here we evaluated the feasibility of an alternative, single cell genomics approach, in the analysis of subsurface microbial community composition, metabolic potential and microevolution at the Sanford Underground Research Facility (SURF), South Dakota, and the Witwaterstrand Basin, South Africa. We successfully recovered genomic DNA from individual microbial cells from multiple locations, including ultra-deep (down to 3,500 m) and low-biomass (down to 10^3 cells mL^-1) fracture water. The obtained single amplified genomes (SAGs) from SURF contained multiple representatives of the candidate divisions OP3, OP11, OD1 and uncharacterized archaea. By sequencing eight of these SAGs, we obtained the first genome content information for these phylum-level lineages that do not contain a single cultured representative. The Witwaterstrand samples were collected from deep fractures, biogeochemical dating of which suggests isolation from tens of thousands to tens of millions of years. Thus, these fractures may be viewed as "underground Galapagos", a natural, long-term experiment of microbial evolution within well-defined temporal and spatial boundaries. We are analyzing multiple SAGs from these environments, which will provide detailed information about adaptations to life in deep subsurface, mutation rates, selective pressures and gene flux within and across microbial populations.

  6. Activation of Peroxymonosulfate by Subsurface Minerals.

    PubMed

    Yu, Miao; Teel, Amy L; Watts, Richard J

    2016-08-01

    In situ chemical oxidation (ISCO) has become a widely used technology for the remediation of soil and groundwater. Although peroxymonosulfate is not a common oxidant source for ISCO, its chemical structure is similar to the ISCO reagents hydrogen peroxide and persulfate, suggesting that peroxymonosulfate may have the beneficial properties of each of these oxidants. Peroxymonosulfate activation in the presence of subsurface minerals was examined as a basis for ISCO, and possible reactive species (hydroxyl radical, sulfate radical, and reductants+nucleophiles) generated in the mineral-activated peroxymonosulfate systems were investigated. Rates of peroxymonosulfate decomposition and generation rates of reactive species were studied in the presence of three iron oxides, one manganese oxide, and three soil fractions. The iron oxide hematite-activated peroxymonosulfate system most effectively degraded the hydroxyl radical probe nitrobenzene. Reductants+nucleophiles were not generated in mineral-activated peroxymonosulfate systems. Use of the probe compound anisole in conjunction with scavengers demonstrated that both sulfate radical and hydroxyl radical are generated in mineral-activated peroxymonosulfate systems. In order to confirm the activation of peroxymonosulfate by subsurface minerals, one natural soil and associated two soil fractions were evaluated as peroxymonosulfate catalysts. The natural soil did not effectively promote the generation of oxidants; however, the soil organic matter was found to promote the generation of reductants + nucleophiles. The results of this research show that peroxymonosulfate has potential as an oxidant source for ISCO applications, and would be most effective in treating halogenated contaminants when soil organic matter is present in the subsurface. PMID:27209171

  7. Holocene Sea Surface and Subsurface Water Mass Variability Reconstructed from Temperature and Sea-ice Proxies in Fram Strait

    NASA Astrophysics Data System (ADS)

    Werner, Kirstin; Spielhagen, Robert F.; Müller, Juliane; Husum, Katrine; Kandiano, Evgenia S.; Polyak, Leonid

    2016-04-01

    In two high-resolution sediment cores from the West Spitsbergen continental margin we investigated planktic foraminiferal, biomarker and dinocyst proxy data in order to reconstruct surface and subsurface water mass variability during the Holocene. The two study sites are today influenced by northward flowing warm and saline Atlantic Water. Both foraminiferal and dinocyst (de Vernal et al., 2013) temperature reconstructions indicate a less-stratified, ice-free, nutrient-rich summer surface ocean with strong Atlantic Water advection between 10.6 and 8.5 cal ka BP, likely related to maximum July insolation during the early Holocene. Sea surface to subsurface water temperatures of up to 6°C prevailed until ca 5 cal ka BP. A weakened contribution of Atlantic Water is found when subsurface temperatures strongly decreased with minimum values between ca 4 and 3 cal ka BP. High planktic foraminifer shell fragmentation and increased oxygen isotope values of the subpolar planktic foraminifer species Turborotalita quinqueloba as well as increasing concentrations of the sea ice biomarker IP25 further indicate cool conditions. Indices associated with IP25 as well as dinocyst data suggest a sustained cooling and consequently sea-ice increase during the late Holocene. However, planktic foraminiferal data indicate a slight return of stronger subsurface influx of Atlantic Water since ca 3 cal ka BP. The observed decoupling of cooling surface and warming subsurface waters during the later Holocene might be attributed to a strong pycnocline layer separating cold sea-ice fed surface waters from enhanced subsurface Atlantic Water advection. Reference: de Vernal, A., Hillaire-Marcel, C., Rochon, A., Fréchette, B., Henry, M., Solignac, S., Bonnet, S., 2013. Dinocyst-based reconstructions of sea ice cover concentration during the Holocene in the Arctic Ocean, the northern North Atlantic Ocean and its adjacent seas. Quaternary Science Reviews 79, 111-121.

  8. Vertical distribution of benthic infauna in continental slope sediments off Cape Lookout, North Carolina

    NASA Astrophysics Data System (ADS)

    Blake, James A.

    The vertical distribution of 30 species of benthic infauna from continental slope (583-3000 m) sediments off Cape Lookout, North Carolina was closely correlated with feeding types. Carnivores, omnivores, filter feeders, and surface deposit feeders were mostly concentrated in the upper 0-2 cm of the cores. The depth distribution of subsurface deposit feeders was more variable, even among related taxa.

  9. Widefield subsurface microscopy of integrated circuits.

    PubMed

    Köklü, Fatih Hakan; Quesnel, Justin I; Vamivakas, Anthony N; Ippolito, Stephen B; Goldberg, Bennett B; Unlü, M Selim

    2008-06-23

    We apply the numerical aperture increasing lens technique to widefield subsurface imaging of silicon integrated circuits. We demonstrate lateral and longitudinal resolutions well beyond the limits of conventional backside imaging. With a simple infrared widefield microscope (lambda(0) = 1.2 microm), we demonstrate a lateral spatial resolution of 0.26 microm (0.22 lambda(0)) and a longitudinal resolution of 1.24 microm (1.03 lambda(0)) for backside imaging through the silicon substrate of an integrated circuit. We present a spatial resolution comparison between widefield and confocal microscopy, which are essential in integrated circuit analysis for emission and excitation microscopy, respectively.

  10. Physiologically anaerobic microorganisms of the deep subsurface

    SciTech Connect

    Stevens, S.E. Jr.; Chung, K.T.

    1991-06-01

    This study seeks to determine numbers, diversity, and morphology of anaerobic microorganisms in 15 samples of subsurface material from the Idaho National Engineering Laboratory, in 18 samples from the Hanford Reservation and in 1 rock sample from the Nevada Test Site; set up long term experiments on the chemical activities of anaerobic microorganisms based on these same samples; work to improve methods for the micro-scale determination of in situ anaerobic microbial activity;and to begin to isolate anaerobes from these samples into axenic culture with identification of the axenic isolates.

  11. Subsurface plankton layers in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Churnside, James H.; Marchbanks, Richard D.

    2015-06-01

    The first synoptic measurements of subsurface plankton layers were made in the western Arctic Ocean in July 2014 using airborne lidar. Layers were detected in open water and in pack ice where up to 90% of the surface was covered by ice. Layers under the ice were less prevalent, weaker, and shallower than those in open water. Layers were more prevalent in the Chukchi Sea than in the Beaufort Sea. Three quarters of the layers observed were thinner than 5 m. The presence of these layers, which are not adequately captured in satellite data, will influence primary productivity, secondary productivity, fisheries recruitment, and carbon export to the benthos.

  12. CLASSIFICATION OF THE MGR SUBSURFACE FACILITY SYSTEM

    SciTech Connect

    R.J. Garrett

    1999-08-31

    The purpose of this analysis is to document the Quality Assurance (QA) classification of the Monitored Geologic Repository (MGR) subsurface facility system structures, systems and components (SSCs) performed by the MGR Safety Assurance Department. This analysis also provides the basis for revision of YMP/90-55Q, Q-List (YMP 1998). The Q-List identifies those MGR SSCs subject to the requirements of DOE/RW-0333P, ''Quality Assurance Requirements and Description'' (QARD) (DOE 1998). This QA classification incorporates the current MGR design and the results of the ''Preliminary Preclosure Design Basis Event Calculations for the Monitored Geologic Repository'' (CRWMS M&O 1998a).

  13. Low temperature monitoring system for subsurface barriers

    SciTech Connect

    Vinegar, Harold J.; McKinzie, II. Billy John

    2009-08-18

    A system for monitoring temperature of a subsurface low temperature zone is described. The system includes a plurality of freeze wells configured to form the low temperature zone, one or more lasers, and a fiber optic cable coupled to at least one laser. A portion of the fiber optic cable is positioned in at least one freeze well. At least one laser is configured to transmit light pulses into a first end of the fiber optic cable. An analyzer is coupled to the fiber optic cable. The analyzer is configured to receive return signals from the light pulses.

  14. Microbiological Transformations of Radionuclides in the Subsurface

    SciTech Connect

    Marshall, Matthew J.; Beliaev, Alex S.; Fredrickson, Jim K.

    2010-01-04

    Microorganisms are ubiquitous in subsurface environments although their populations sizes and metabolic activities can vary considerably depending on energy and nutrient inputs. As a result of their metabolic activities and the chemical properties of their cell surfaces and the exopolymers they produce, microorganisms can directly or indirectly facilitate the biotransformation of radionuclides, thus altering their solubility and overall fate and transport in the environment. Although biosorption to cell surfaces and exopolymers can be an important factor modifying the solubility of some radionuclides under specific conditions, oxidation state is often considered the single most important factor controlling their speciation and, therefore, environmental behavior.

  15. Enabling computational technologies for subsurface simulations

    SciTech Connect

    Falgout, R D

    1999-02-22

    We collaborated with Environmental Programs to develop and apply advanced computational methodologies for simulating multiphase flow through heterogeneous porous media. The primary focus was on developing a fast accurate advection scheme using a new temporal subcycling technique and on the scalable and efficient solution of the nonlinear Richards' equation used to model two-phase (variably saturated) flow. The resulting algorithms can be orders-of-magnitude faster than existing methods. Our computational technologies were applied to the simulation of subsurface fluid flow and chemical transport in the context of two important applications: water resource management and groundwater remediation.

  16. Nonisothermal multiphase subsurface transport on parallel computers

    SciTech Connect

    Martinez, M.J.; Hopkins, P.L.; Shadid, J.N.

    1997-10-01

    We present a numerical method for nonisothermal, multiphase subsurface transport in heterogeneous porous media. The mathematical model considers nonisothermal two-phase (liquid/gas) flow, including capillary pressure effects, binary diffusion in the gas phase, conductive, latent, and sensible heat transport. The Galerkin finite element method is used for spatial discretization, and temporal integration is accomplished via a predictor/corrector scheme. Message-passing and domain decomposition techniques are used for implementing a scalable algorithm for distributed memory parallel computers. An illustrative application is shown to demonstrate capabilities and performance.

  17. Instrumented Moles for Planetary Subsurface Regolith Studies

    NASA Astrophysics Data System (ADS)

    Richter, L. O.; Coste, P. A.; Grzesik, A.; Knollenberg, J.; Magnani, P.; Nadalini, R.; Re, E.; Romstedt, J.; Sohl, F.; Spohn, T.

    2006-12-01

    Soil-like materials, or regolith, on solar system objects provide a record of physical and/or chemical weathering processes on the object in question and as such possess significant scientific relevance for study by landed planetary missions. In the case of Mars, a complex interplay has been at work between impact gardening, aeolian as well as possibly fluvial processes. This resulted in regolith that is texturally as well as compositionally layered as hinted at by results from the Mars Exploration Rover (MER) missions which are capable of accessing shallow subsurface soils by wheel trenching. Significant subsurface soil access on Mars, i.e. to depths of a meter or more, remains to be accomplished on future missions. This has been one of the objectives of the unsuccessful Beagle 2 landed element of the ESA Mars Express mission having been equipped with the Planetary Underground Tool (PLUTO) subsurface soil sampling Mole system capable of self-penetration into regolith due to an internal electro-mechanical hammering mechanism. This lightweight device of less than 900 g mass was designed to repeatedly obtain and deliver to the lander regolith samples from depths down to 2 m which would have been analysed for organic matter and, specifically, organic carbon from potential extinct microbial activity. With funding from the ESA technology programme, an evolved Mole system - the Instrumented Mole System (IMS) - has now been developed to a readiness level of TRL 6. The IMS is to serve as a carrier for in situ instruments for measurements in planetary subsurface soils. This could complement or even eliminate the need to recover samples to the surface. The Engineering Model hardware having been developed within this effort is designed for accommodating a geophysical instrument package (Heat Flow and Physical Properties Package, HP3) that would be capable of measuring regolith physical properties and planetary heat flow. The chosen design encompasses a two-body Mole

  18. Airborne Electromagnetic Mapping of Subsurface Permafrost

    NASA Astrophysics Data System (ADS)

    Abraham, J. D.; Minsley, B. J.; Cannia, J. C.; Smith, B. D.; Walvoord, M. A.; Voss, C. I.; Jorgenson, T. T.; Wylie, B. K.; Anderson, L.

    2011-12-01

    Concerns over the impacts of climate change have recently energized research on the potential impacts thawing permafrost may have on groundwater flow, infrastructure, forest health, ecosystems, energy production, CO2 release, and contaminant transport. There is typically little knowledge about subsurface permafrost distributions, such as thickness and where groundwater-surface-water connections may occur through taliks. In June of 2010, the U.S. Geological Survey undertook an airborne electromagnetic (AEM) survey in the area of Fort Yukon, Alaska in order to map the 3-D distribution of permafrost and provide information for the development of groundwater models within the Yukon River Basin. Prior to the development of these models, information on areas of groundwater-surface water interaction was extremely limited. Lithology determined from a borehole drilled in Fort Yukon in 1994 agrees well with the resistivity depth sections inferred from the airborne survey. In addition to lithology, there a thermal imprint appears on the subsurface resistivity values. In the upper 20-50 m, the sections show continuous areas of high electrical resistivity, consistent with alluvial gravel deposits that are likely frozen. At depth, unfrozen gravel deposits have intermediate-to-high resistivity; frozen silts have intermediate resistivity; and unfrozen silts have low resistivity. Under the Yukon River and lakes where the subsurface is not frozen, zones of moderate resistivity intermix with areas of low resistivity. The areas of loess hills on the margins of the Yukon Flats have very-high electrical resistivity, indicating higher ice content, and are associated with the some of the greatest thickness of permafrost in the survey area. This work provides the first look into the 3-D distribution of permafrost in the areas around Fort Yukon and is a demonstration of the application of AEM to permafrost mapping. The AEM survey provides unprecedented 3-D images of subsurface electrical

  19. Detection of microbes in the subsurface

    NASA Technical Reports Server (NTRS)

    White, David C.; Tunlid, Anders

    1989-01-01

    The search for evidence of microbial life in the deep subsurface of Earth has implications for the Mars Rover Sampling Return Missions program. If suitably protected environments can be found on Mars then the instrumentation to detect biomarkers could be used to examine the molecular details. Finding a lipid in Martian soil would represent possibly the simplest test for extant or extinct life. A device that could do a rapid extraction possibly using the supercritical fluid technology under development now with a detection of the carbon content would clearly indicate a sample to be returned.

  20. Transport of subsurface bacteria in porous media

    SciTech Connect

    Bales, R.C.; Arnold, R.G.; Gerba, C.P.

    1995-02-01

    The primary objective of this study was to develop tools with which to measure the advective transport of microorganisms through porous media. These tools were then applied to investigate the sorptive properties of representative microorganisms that were selected at random from the DOE`s deep subsurface collection of bacterial, maintained at Florida State University. The transport screening procedure that arose from this study was also used to investigate biological factors that affect the transport/sorption of biocolloids during their movement through porous media with the bulk advective flow.

  1. Evidence for the migration of steroidal estrogens through river bed sediments.

    PubMed

    Labadie, Pierre; Cundy, Andrew B; Stone, Kevin; Andrews, Michael; Valbonesi, Sam; Hill, Elizabeth M

    2007-06-15

    Estrogenic substances discharged from wastewater treatment plants have been detected in surface sediments of receiving waters, but little is known of their vertical migration through buried sediments and their potential to contaminate subsurface waters. The vertical profiles of estrogenic chemicals were investigated in sediment cores at an alluvial freshwater site (Ditchling) and a clay-rich estuarine site (Lewes), both of which are downstream of wastewater discharges into the River Ouse (Sussex, U.K.). Estrone (E1) was the predominant estrogen detected in surface and buried sediments at both sites and was detected in undisturbed clay sediments > 120 years old. Profiles of E1 at Ditchling were characterized by a prominent subsurface peak of E1 at the alluvium/clay interface (-15 cm) at a concentration (28.8 +/- 6.0 ng/g of dry wt) that was 9-fold higher than in the surface sediment. In contrast, a steady downcore decline in E1 concentrations was observed in the clay-rich Lewes core. This work provides the first in situ evidence of estrogen migration through river bed sediments and reveals that movement of estrogens through unconsolidated sediment can result in penetration to the underlying substrata and therefore the potential for groundwater contamination.

  2. CL-20 Reactivity in the Subsurface Environment and Potential for Migration

    SciTech Connect

    Szecsody, Jim E.; Girvin, Donald C.; Qasim, Mohammad M.

    2004-07-07

    Hexanitrohexaazaisowurtzitane (CL-20) is being considered by DoD as a replacement for existing propellant and explosives. This SERDP-funded study is focused on quantification of geochemical and microbial reactions of CL-20 in sediments and transport in the subsurface environment. CL-20 is unstable in aqueous alkaline conditions (pH > 9.0), but is stable with some sediments for a year or more. Low sorption and slow degradation rates observed with oxic sediments indicate a high potential for deep migration of CL-20 (similar to RDX). Sorption of CL-20 is relatively small (Kd = 0.02 to 4.2 cm3 g-1, which results in only slight to moderate retardation relative to water (i.e., Rf 1.1 to 12). In oxic systems, CL-20 abiotically degrades at slow rates (i.e., 10s to 100s of hours) in a wide variety of sediments, but at fast rates (i.e., minutes) in the presence of 2:1 smectite clays and ferrous iron oxides. CL-20 was degraded rapidly in sediments under iron reducing conditions, demonstrating that reduced iron technologies for groundwater remediation of RDX and TNT may work for CL-20. The degradation process in reduced sediments was investigated further using specific ferrous iron phases. CL-20 was rapidly degraded with adsorbed Fe(II) on amorphous iron oxides or clays, but not adsorbed Fe(II) on silica or feldspar. Because iron oxides delocalize electrons from adsorbed Fe(II), this may increase the rate of CL-20 degradation. CL-20 degradation was also at moderate rates in the presence of minerals containing only structural Fe(II). CL-20 oxic degradation produced 2 to 4 moles of nitrate with little carbon mass, whereas anaerobic degradation produced mainly low-molecular weight compounds that are aromatic. This degradation pathway in a reducing environment may follow C-C bond breaking, as predicted from molecular modeling. Identification of further degradation products and CL-20 mineralization rates is needed to fully assess the impact of these CL-20 transformation rates on

  3. Contaminated Sediment Core Profiling

    EPA Science Inventory

    Evaluating the environmental risk of sites containing contaminated sediments often poses major challenges due in part to the absence of detailed information available for a given location. Sediment core profiling is often utilized during preliminary environmental investigations ...

  4. Sediment Toxicity Identification Evaluation

    EPA Science Inventory

    Approach combining chemical manipulations and aquatic toxicity testing, generally with whole organisms, to systematically characterize, identify and confirm toxic substances causing toxicity in whole sediments and sediment interstitial waters. The approach is divided into thre...

  5. Fluvial sediment concepts

    USGS Publications Warehouse

    Guy, Harold P.

    1970-01-01

    This report is the first of a series concerned with the measurement of and recording of information about fluvial sediment and with related environmental data needed to maintain and improve basic sediment knowledge. Concepts presented in this report involve (1) the physical characteristics of sediment which include aspects relative 'to weathering, soils, resistance to erosion, and particle size, (2) sediment erosion, transport, and deposition characteristics, which include aspects relative to fine sediment and overland flow, coarse sediment and streamflow, variations in stream sediment concentration, deposition, and denudation, (3) geomorphic considerations, which include aspects relative to the drainage basin, mass wasting, and channel properties, (4) economic aspects, and (5) data needs and program objectives to be attained through the use of several kinds of sediment records.

  6. Optimal Electromagnetic (EM) Geophysical Techniques to Map the Concentration of Subsurface Ice and Adsorbed Water on Mars and the Moon

    NASA Astrophysics Data System (ADS)

    Stillman, D. E.; Grimm, R. E.

    2013-12-01

    Water ice is ubiquitous in our Solar System and is a probable target for planetary exploration. Mapping the lateral and vertical concentration of subsurface ice from or near the surface could determine the origin of lunar and martian ice and quantify a much-needed resource for human exploration. Determining subsurface ice concentration on Earth is not trivial and has been attempted previously with electrical resistivity tomography (ERT), ground penetrating radar (GPR), airborne EM (AEM), and nuclear magnetic resonance (NMR). These EM geophysical techniques do not actually detect ice, but rather the absence of unfrozen water. This causes a non-unique interpretation of frozen and dry subsurface sediments. This works well in the arctic because most locations are not dry. However, for planetary exploration, liquid water is exceedingly rare and subsurface mapping must discriminate between an ice-rich and a dry subsurface. Luckily, nature has provided a unique electrical signature of ice: its dielectric relaxation. The dielectric relaxation of ice creates a temperature and frequency dependence of the electrical properties and varies the relative dielectric permittivity from ~3.1 at radar frequencies to >100 at low frequencies. On Mars, sediments smaller than silt size can hold enough adsorbed unfrozen water to complicate the measurement. This is because the presence of absorbed water also creates frequency-dependent electrical properties. The dielectric relaxation of adsorbed water and ice can be separated as they have different shapes and frequency ranges as long as a spectrum spanning the two relaxations is measured. The volume concentration of ice and adsorbed water is a function of the strength of their relaxations. Therefore, we suggest that capacitively-coupled dielectric spectroscopy (a.k.a. spectral induced polarization or complex resistivity) can detect the concentration of both ice and adsorbed water in the subsurface. To prove this concept we have collected

  7. Crystal structure of laser-induced subsurface modifications in Si

    DOE PAGES

    Verburg, P. C.; Smillie, L. A.; Römer, G. R. B. E.; Haberl, B.; Bradby, J. E.; Williams, J. S.; Huis in ’t Veld, A. J.

    2015-06-04

    Laser-induced subsurface modification of dielectric materials is a well-known technology. Applications include the production of optical components and selective etching. In addition to dielectric materials, the subsurface modification technology can be applied to silicon, by employing near to mid-infrared radiation. An application of subsurface modifications in silicon is laser-induced subsurface separation, which is a method to separate wafers into individual dies. Other applications for which proofs of concept exist are the formation of waveguides and resistivity tuning. However, limited knowledge is available about the crystal structure of subsurface modifications in silicon. In this paper, we investigate the geometry and crystalmore » structure of laser-induced subsurface modifications in monocrystalline silicon wafers. Finally, in addition to the generation of lattice defects, we found that transformations to amorphous silicon and Si-iii/Si-xii occur as a result of the laser irradiation.« less

  8. Crystal structure of laser-induced subsurface modifications in Si

    SciTech Connect

    Verburg, P. C.; Smillie, L. A.; Römer, G. R. B. E.; Haberl, B.; Bradby, J. E.; Williams, J. S.; Huis in ’t Veld, A. J.

    2015-06-04

    Laser-induced subsurface modification of dielectric materials is a well-known technology. Applications include the production of optical components and selective etching. In addition to dielectric materials, the subsurface modification technology can be applied to silicon, by employing near to mid-infrared radiation. An application of subsurface modifications in silicon is laser-induced subsurface separation, which is a method to separate wafers into individual dies. Other applications for which proofs of concept exist are the formation of waveguides and resistivity tuning. However, limited knowledge is available about the crystal structure of subsurface modifications in silicon. In this paper, we investigate the geometry and crystal structure of laser-induced subsurface modifications in monocrystalline silicon wafers. Finally, in addition to the generation of lattice defects, we found that transformations to amorphous silicon and Si-iii/Si-xii occur as a result of the laser irradiation.

  9. Distribution and geochemistry of contaminated subsurface waters in fissured volcanogenic bed rocks of the Lake Karachai Area, Chelyabinsk, Southern Urals

    SciTech Connect

    Solodov, I.N.; Belichkin, V.I.; Zotov, A.V.; Kochkin, B.T.; Drozhko, E.G.; Glagolev, A.V.; Skokov, A.N.

    1994-06-01

    The present investigation is devoted to the study of the distribution and geochemistry of contaminated subsurface waters, beneath the site of temporary storage of liquid radioactive waste known as Lake Karachai. For this purpose a method of hydrogeochemical logging (HGCL) together with standard hydrogeochemical and geophysical methods of uncased hole logging were used. The distribution of sodium nitrate brine plumes in the subsurface was determined by the physical and physico-chemical properties of these brines and by the petrochemical composition of enclosing rocks and the structural setting of the flow paths. The latter is represented by fractures and large faults in the bedrock of volcanogenic and volcanogenic-sedimentary rocks of intermediate-to-basic composition. The volcanogenic rocks are overlain in some places by a thin cover of unconsolidated sediments, i.e., by loams and relatively impermeable silts. Contaminated waters flow-in accordance with the eluvium bottom relief towards local areas of natural (Mishelyak and Techa rivers) and artificial (Novogomenskii water intake) discharge of subsurface waters. The large Mishelyak fault, southwest of Lake Karachai and under fluvial sediments of the Mishelyak, is assumed to significantly influence the flow pattern of contaminated waters, diverting them from an intake of drinking water.

  10. Laterally spreading iron, humic-like dissolved organic matter and nutrients in cold, dense subsurface water of the Arctic Ocean.

    PubMed

    Hioki, Nanako; Kuma, Kenshi; Morita, Yuichirou; Sasayama, Ryouhei; Ooki, Atsushi; Kondo, Yoshiko; Obata, Hajime; Nishioka, Jun; Yamashita, Youhei; Nishino, Shigeto; Kikuchi, Takashi; Aoyama, Michio

    2014-10-27

    The location and magnitude of oceanic iron sources remain uncertain owing to a scarcity of data, particularly in the Arctic Ocean. The formation of cold, dense water in the subsurface layer of the western Arctic Ocean is a key process in the lateral transport of iron, macronutrients, and other chemical constituents. Here, we present iron, humic-like fluorescent dissolved organic matter, and nutrient concentration data in waters above the continental slope and shelf and along two transects across the shelf-basin interface in the western Arctic Ocean. We detected high concentrations in shelf bottom waters and in a plume that extended in the subsurface cold dense water of the halocline layer in slope and basin regions. At σθ = 26.5, dissolved Fe, humic-like fluorescence intensity, and nutrient maxima coincided with N* minima (large negative values of N* indicate significant denitrification within shelf sediments). These results suggest that these constituents are supplied from the shelf sediments and then transported laterally to basin regions. Humic dissolved organic matter probably plays the most important role in the subsurface maxima and lateral transport of dissolved Fe in the halocline layer as natural Fe-binding organic ligand.

  11. Laterally spreading iron, humic-like dissolved organic matter and nutrients in cold, dense subsurface water of the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Hioki, Nanako; Kuma, Kenshi; Morita, Yuichirou; Sasayama, Ryouhei; Ooki, Atsushi; Kondo, Yoshiko; Obata, Hajime; Nishioka, Jun; Yamashita, Youhei; Nishino, Shigeto; Kikuchi, Takashi; Aoyama, Michio

    2014-10-01

    The location and magnitude of oceanic iron sources remain uncertain owing to a scarcity of data, particularly in the Arctic Ocean. The formation of cold, dense water in the subsurface layer of the western Arctic Ocean is a key process in the lateral transport of iron, macronutrients, and other chemical constituents. Here, we present iron, humic-like fluorescent dissolved organic matter, and nutrient concentration data in waters above the continental slope and shelf and along two transects across the shelf-basin interface in the western Arctic Ocean. We detected high concentrations in shelf bottom waters and in a plume that extended in the subsurface cold dense water of the halocline layer in slope and basin regions. At σθ = 26.5, dissolved Fe, humic-like fluorescence intensity, and nutrient maxima coincided with N* minima (large negative values of N* indicate significant denitrification within shelf sediments). These results suggest that these constituents are supplied from the shelf sediments and then transported laterally to basin regions. Humic dissolved organic matter probably plays the most important role in the subsurface maxima and lateral transport of dissolved Fe in the halocline layer as natural Fe-binding organic ligand.

  12. Laterally spreading iron, humic-like dissolved organic matter and nutrients in cold, dense subsurface water of the Arctic Ocean.

    PubMed

    Hioki, Nanako; Kuma, Kenshi; Morita, Yuichirou; Sasayama, Ryouhei; Ooki, Atsushi; Kondo, Yoshiko; Obata, Hajime; Nishioka, Jun; Yamashita, Youhei; Nishino, Shigeto; Kikuchi, Takashi; Aoyama, Michio

    2014-01-01

    The location and magnitude of oceanic iron sources remain uncertain owing to a scarcity of data, particularly in the Arctic Ocean. The formation of cold, dense water in the subsurface layer of the western Arctic Ocean is a key process in the lateral transport of iron, macronutrients, and other chemical constituents. Here, we present iron, humic-like fluorescent dissolved organic matter, and nutrient concentration data in waters above the continental slope and shelf and along two transects across the shelf-basin interface in the western Arctic Ocean. We detected high concentrations in shelf bottom waters and in a plume that extended in the subsurface cold dense water of the halocline layer in slope and basin regions. At σθ = 26.5, dissolved Fe, humic-like fluorescence intensity, and nutrient maxima coincided with N* minima (large negative values of N* indicate significant denitrification within shelf sediments). These results suggest that these constituents are supplied from the shelf sediments and then transported laterally to basin regions. Humic dissolved organic matter probably plays the most important role in the subsurface maxima and lateral transport of dissolved Fe in the halocline layer as natural Fe-binding organic ligand. PMID:25345398

  13. Interstitial brines in playa sediments

    USGS Publications Warehouse

    Jones, B.F.; Van Denburgh, A.S.; Truesdell, A.H.; Rettig, S.L.

    1969-01-01

    Study of several closed drainages in the Great Basin has shown that the interstitial solutions of shallow, fine-grained playa deposits store a large quantity of dissolved solids and are often more concentrated than associated lakes and ponds, except in peripheral zones of stream or ground-water inflow. These interstitial fluids, when compared with local runoff, impoundments, or spring waters, commonly have a distinctive ionic composition which sometimes cannot be explained by either simple mixing of surface and subsurface inflow or by evaporative concentration. At Abert Lake, Oregon, the interstitial solute concentrations increased with depth to values as much as five times greater than the lake, except where springs indicate significant ground-water input. Where Na+, Cl, and CO2 species constitute more than 90% of the solutes, Na+ Cl- ratios in the lake water are lower than in interstitial solutions of bottom cores and higher than in playa fluids. At the same time, Na+ K+ ratios are highest in the fluids of lake bottom muds and lowest in playa interstitials. In deeper playa profiles, interstitial Na+ Cl- tended to decrease with depth (5 ft. maximum). In the Abert Lake area, as in other parts of the western Great Basin, Na+ Cl- ratios are indicative of total CO2 in solution and the effects of organic decay in surficial sediments. These ratios, coupled with data on silica and bulk density, show that higher PCO2 accompanying decay promotes silicate dissolution and hydrogen ion exchange, stripping alkalis from sediment which had preferentially adsorbed K+ when entering the lake. On subsequent loss of pore fluid in the playa regime, silica initially released to solution in the lake environment is readsorbed on dissolution products. ?? 1969.

  14. Atmospheric energy for subsurface life on Mars?

    PubMed Central

    Weiss, Benjamin P.; Yung, Yuk L.; Nealson, Kenneth H.

    2000-01-01

    The location and density of biologically useful energy sources on Mars will limit the biomass, spatial distribution, and organism size of any biota. Subsurface Martian organisms could be supplied with a large energy flux from the oxidation of photochemically produced atmospheric H2 and CO diffusing into the regolith. However, surface abundance measurements of these gases demonstrate that no more than a few percent of this available flux is actually being consumed, suggesting that biological activity driven by atmospheric H2 and CO is limited in the top few hundred meters of the subsurface. This is significant because the available but unused energy is extremely large: for organisms at 30-m depth, it is 2,000 times previous estimates of hydrothermal and chemical weathering energy and far exceeds the energy derivable from other atmospheric gases. This also implies that the apparent scarcity of life on Mars is not attributable to lack of energy. Instead, the availability of liquid water may be a more important factor limiting biological activity because the photochemical energy flux can only penetrate to 100- to 1,000-m depth, where most H2O is probably frozen. Because both atmospheric and Viking lander soil data provide little evidence for biological activity, the detection of short-lived trace gases will probably be a better indicator of any extant Martian life. PMID:10660689

  15. Atmospheric energy for subsurface life on Mars?

    NASA Technical Reports Server (NTRS)

    Weiss, B. P.; Yung, Y. L.; Nealson, K. H.

    2000-01-01

    The location and density of biologically useful energy sources on Mars will limit the biomass, spatial distribution, and organism size of any biota. Subsurface Martian organisms could be supplied with a large energy flux from the oxidation of photochemically produced atmospheric H(2) and CO diffusing into the regolith. However, surface abundance measurements of these gases demonstrate that no more than a few percent of this available flux is actually being consumed, suggesting that biological activity driven by atmospheric H(2) and CO is limited in the top few hundred meters of the subsurface. This is significant because the available but unused energy is extremely large: for organisms at 30-m depth, it is 2,000 times previous estimates of hydrothermal and chemical weathering energy and far exceeds the energy derivable from other atmospheric gases. This also implies that the apparent scarcity of life on Mars is not attributable to lack of energy. Instead, the availability of liquid water may be a more important factor limiting biological activity because the photochemical energy flux can only penetrate to 100- to 1,000-m depth, where most H(2)O is probably frozen. Because both atmospheric and Viking lander soil data provide little evidence for biological activity, the detection of short-lived trace gases will probably be a better indicator of any extant Martian life.

  16. Phylogenetic relationships among subsurface microorganisms. Progress report

    SciTech Connect

    Nierzwicki-Bauer, S.A.

    1991-12-31

    This project involves the development of group specific 16S ribosomal RNA-targeted oligonucleotide hybridization probes for the rapid detection of specific types of subsurface organisms (e.g., groups of microbes that share certain physiological traits). Major accomplishments for the period of 6/91 to 12/1/91 are described. Nine new probes have been synthesized on the basis of published 16S rRNA sequence data from the Ribosomal Database Project. We have initiated rapid screening of many of the subsurface microbial isolates obtained from the P24 borehole at the Savannah River Site. To date, we have screened approximately 50% of the isolates from P24. We have optimized our {und in situ} hybridization technique, and have developed a cell blot hybridization technique to screen 96 samples on a single blot. This is much faster than reading 96 individual slides. Preliminary experiments have been carried out which indicate specific nutrients can be used to amplify rRNA only in those organisms capable of metabolizing those nutrients. 1 tab., 2 figs.

  17. Atmospheric energy for subsurface life on Mars?

    PubMed

    Weiss, B P; Yung, Y L; Nealson, K H

    2000-02-15

    The location and density of biologically useful energy sources on Mars will limit the biomass, spatial distribution, and organism size of any biota. Subsurface Martian organisms could be supplied with a large energy flux from the oxidation of photochemically produced atmospheric H(2) and CO diffusing into the regolith. However, surface abundance measurements of these gases demonstrate that no more than a few percent of this available flux is actually being consumed, suggesting that biological activity driven by atmospheric H(2) and CO is limited in the top few hundred meters of the subsurface. This is significant because the available but unused energy is extremely large: for organisms at 30-m depth, it is 2,000 times previous estimates of hydrothermal and chemical weathering energy and far exceeds the energy derivable from other atmospheric gases. This also implies that the apparent scarcity of life on Mars is not attributable to lack of energy. Instead, the availability of liquid water may be a more important factor limiting biological activity because the photochemical energy flux can only penetrate to 100- to 1,000-m depth, where most H(2)O is probably frozen. Because both atmospheric and Viking lander soil data provide little evidence for biological activity, the detection of short-lived trace gases will probably be a better indicator of any extant Martian life.

  18. Method and apparatus for subsurface exploration

    NASA Technical Reports Server (NTRS)

    Wilcox, Brian (Inventor)

    2002-01-01

    A subsurface explorer (SSX) for exploring beneath the terrestrial surface of planetary bodies such as the Earth, Mars, or comets. This exploration activity utilizes appropriate sensors and instrument to evaluate the composition, structure, mineralogy and possibly biology of the subsurface medium, as well as perhaps the ability to return samples of that medium back to the surface. The vehicle comprises an elongated skin or body having a front end and a rear end, with a nose piece at the front end for imparting force to composition material of the planetary body. Force is provided by a hammer mechanism to the back side of a nose piece from within the body of the vehicle. In the preferred embodiment, a motor spins an intermediate shaft having two non-uniform threads along with a hammer which engages these threads with two conical rollers. A brake assembly halts the rotation of the intermediate shaft, causing the conical roller to spin down the non-uniform thread to rapidly and efficiently convert the rotational kinetic energy of the hammer into translational energy.

  19. The subsurface of Pluto from submillimetre observations

    NASA Astrophysics Data System (ADS)

    Greaves, J. S.; Whitelaw, A. C. M.; Bendo, G. J.

    2015-04-01

    Surface areas on Pluto change in brightness and colour, at optical to infrared wavelengths, over time-scales as short as years. The subsurface contains a reservoir of frozen volatiles, but little is known about it because Pluto is out of reach for cm-radar. Here we present a 0.85 mm wavelength light curve of the Pluto system, from archival data taken in 1997 August with the SCUBA (Submillimetre Common-User Bolometer Array) camera on the James Clerk Maxwell Telescope (JCMT). This wavelength probes for the first time to just below the skin depth of thermal changes over Pluto's day. The light curve differs significantly from counterparts in the mid- to far-infrared, in a longitude range that is optically dark on Pluto's surface. An estimate from Herschel of the 0.5 mm flux in 2012 is comparable to the mean 0.45 mm flux from SCUBA in 1997, suggesting that layers centimetres below the surface have not undergone any gross temperature change. The longitudes that are relatively submillimetre-faint could have a different emissivity, perhaps with a subsurface layer richer in nitrogen or methane ices than at the surface. The Radio Science Experiment (REX) instrument on New Horizons may be able to constrain physical properties deeper down, as it looks back on Pluto's nightside after the 2015 July flyby.

  20. Viral activities and life cycles in deep subseafloor sediments.

    PubMed

    Engelhardt, Tim; Orsi, William D; Jørgensen, Bo Barker

    2015-12-01

    Viruses are highly abundant in marine subsurface sediments and can even exceed the number of prokaryotes. However, their activity and quantitative impact on microbial populations are still poorly understood. Here, we use gene expression data from published continental margin subseafloor metatranscriptomes to qualitatively assess viral diversity and activity in sediments up to 159 metres below seafloor (mbsf). Mining of the metatranscriptomic data revealed 4651 representative viral homologues (RVHs), representing 2.2% of all metatranscriptome sequence reads, which have close translated homology (average 77%, range 60-97% amino acid identity) to viral proteins. Archaea-infecting RVHs are exclusively detected in the upper 30 mbsf, whereas RVHs for filamentous inoviruses predominate in the deepest sediment layers. RVHs indicative of lysogenic phage-host interactions and lytic activity, notably cell lysis, are detected at all analysed depths and suggest a dynamic virus-host association in the marine deep biosphere studied here. Ongoing lytic viral activity is further indicated by the expression of clustered, regularly interspaced, short palindromic repeat-associated cascade genes involved in cellular defence against viral attacks. The data indicate the activity of viruses in subsurface sediment of the Peruvian margin and suggest that viruses indeed cause cell mortality and may play an important role in the turnover of subseafloor microbial biomass. PMID:26109514

  1. Viral activities and life cycles in deep subseafloor sediments.

    PubMed

    Engelhardt, Tim; Orsi, William D; Jørgensen, Bo Barker

    2015-12-01

    Viruses are highly abundant in marine subsurface sediments and can even exceed the number of prokaryotes. However, their activity and quantitative impact on microbial populations are still poorly understood. Here, we use gene expression data from published continental margin subseafloor metatranscriptomes to qualitatively assess viral diversity and activity in sediments up to 159 metres below seafloor (mbsf). Mining of the metatranscriptomic data revealed 4651 representative viral homologues (RVHs), representing 2.2% of all metatranscriptome sequence reads, which have close translated homology (average 77%, range 60-97% amino acid identity) to viral proteins. Archaea-infecting RVHs are exclusively detected in the upper 30 mbsf, whereas RVHs for filamentous inoviruses predominate in the deepest sediment layers. RVHs indicative of lysogenic phage-host interactions and lytic activity, notably cell lysis, are detected at all analysed depths and suggest a dynamic virus-host association in the marine deep biosphere studied here. Ongoing lytic viral activity is further indicated by the expression of clustered, regularly interspaced, short palindromic repeat-associated cascade genes involved in cellular defence against viral attacks. The data indicate the activity of viruses in subsurface sediment of the Peruvian margin and suggest that viruses indeed cause cell mortality and may play an important role in the turnover of subseafloor microbial biomass.

  2. Iron monosulfide accumulation and pyrite formation in eutrophic estuarine sediments

    NASA Astrophysics Data System (ADS)

    Kraal, Peter; Burton, Edward D.; Bush, Richard T.

    2013-12-01

    This study investigates iron (Fe) and sulfur (S) cycling in sediments from the eutrophic Peel-Harvey Estuary in Western Australia, which is subject to localized accumulation of strongly reducing, organic- and sulfide-rich sediments. Sedimentary iron was mostly present in highly reactive form (on average 73% of total Fe) and showed extensive sulfidization even in surface sediments, despite being overlain by a well-mixed oxygenated water column. This indicates that, under eutrophic marine conditions, Fe sulfidization may be driven by reductive processes in the sediment without requiring oxygen depletion in the overlying waters. Strong enrichments in iron monosulfide (FeS > 300 μmol g-1) were observed in fine-grained sediment intervals up to 45 cm depth. This metastable Fe sulfide is commonly restricted to thin subsurface sediment intervals, below which pyrite (FeS2) dominates. Our findings suggest inhibition of the dissolution-precipitation processes that replace FeS with FeS2 in sediments. Rates of pyrite formation based on the FeS2 profiles were much lower than those predicted by applying commonly used kinetic equations for pyrite formation. Dissolved H2S was present at millimolar levels throughout the investigated sediment profiles. This may indicate that (i) pyrite formation via reaction between dissolved Fe (including Fe clusters) and H2S was limited by low availability of dissolved Fe or (ii) reaction kinetics of pyrite formation via the H2S pathway may be relatively slow in natural reducing sediments. We propose that rapid burial of the FeS under anoxic conditions in these organic-rich reducing sediments minimizes the potential for pyrite formation, possibly by preventing dissolution of FeS or by limiting the availability of oxidized sulfur species that are required for pyrite formation via the polysulfide pathway.

  3. Impact of overpressures on subsurface exploration and reservoir management

    NASA Astrophysics Data System (ADS)

    Kukla, P.

    2009-04-01

    The presence of overpressures in the subsurface poses major problems for safety and cost efficient well design, but less well known is their importance for exploration and reservoir development. Overpressures reduce the vertical effective stress (VES, the difference between the vertical stress and fluid pressure) experienced by the sediment. As sediment compaction is primarily an irreversible function of VES, a reduction in VES will halt compaction. Similarly, a reduction in its rate of increase will reduce the rate of porosity loss. Porosity and other key rock properties will therefore reflect changes in vertical effective stress. Any measurement that senses porosity, or seismic velocity (e.g. sonic, density or resistivity logs) will provide a means of estimating overpressures. The reduction of porosity with vertical effective stress is exponential in nature. Consequently, overpressures generated early in the burial history, such as those generated by disequilibrium compaction, will have a greater impact on rock properties than those generated or emplaced during late burial. Indeed, late overpressuring, so-called inflation, may have little or no impact on rock properties and therefore methods for the prediction of overpressures from properties such as seismic velocity will not provide reliable pressure estimates. In order for fluid pressures to rise in a basin, the pressures have to be contained by rocks with sufficiently low permeability. Overpressures are transient and gradually leak away when the generation mechanism ceases to operate. In some areas, such as in parts of the central North Sea and the Middle East, fluid pressures have built up until the failure envelope of the seal is reached, leading to a subsequent loss of the sealing capacity. The failure envelope is usually considered to be determined by the minimum horizontal stress. The failure pressure for the seal systematically increases with depth and this variation will control the maximum pressures

  4. Lateral subsurface flow pathways in a semiarid Ponderosa pine hillslope

    NASA Astrophysics Data System (ADS)

    Newman, Brent D.; Campbell, Andrew R.; Wilcox, Bradford P.

    1998-12-01

    The mechanisms controlling lateral subsurface flow in semiarid environments have received relatively little attention despite the fact that lateral subsurface flow can be an important runoff process in these environments. The objective of the current study is to better understand lateral subsurface flow process in semiarid environments. Natural chloride, dissolved organic carbon, and stable isotope (δD and δ18O) tracers were used to investigate the lateral subsurface flow process and the chemical changes that occur as a result of lateral subsurface flow. Observed differences in chemistry between soil matrix water and lateral subsurface flow were large (for example, chloride concentrations in matrix soil water samples were >200 mg/L, compared with only 2 mg/L in lateral subsurface flow samples obtained at the same time). This difference in chemistry is indicative of a two-domain flow system in which macropores conduct lateral subsurface flow that is not in chemical or hydrological equilibrium with the soil matrix. The size of precipitation events appeared to have a strong influence on the variations in old/new water percentages, and examples of both old and new water dominated events were observed. There were also large variations in the chemistry of lateral subsurface flow with time. For example, chloride and dissolved organic carbon concentrations were 10 and 70 times greater, respectively, under saturated conditions than under unsaturated conditions.

  5. Modeling subsurface stormflow initiation in low-relief landscapes

    NASA Astrophysics Data System (ADS)

    Hopp, Luisa; Vaché, Kellie B.; Rhett Jackson, C.; McDonnell, Jeffrey J.

    2015-04-01

    Shallow lateral subsurface flow as a runoff generating mechanism at the hillslope scale has mostly been studied in steeper terrain with typical hillside angles of 10 - 45 degrees. These studies have shown that subsurface stormflow is often initiated at the interface between a permeable upper soil layer and a lower conductivity impeding layer, e.g. a B horizon or bedrock. Many studies have identified thresholds of event size and soil moisture states that need to be exceeded before subsurface stormflow is initiated. However, subsurface stormflow generation on low-relief hillslopes has been much less studied. Here we present a modeling study that investigates the initiation of subsurface stormflow on low-relief hillslopes in the Upper Coastal Plain of South Carolina, USA. Hillslopes in this region typically have slope angles of 2-5 degrees. Topsoils are sandy, underlain by a low-conductivity sandy clay loam Bt horizon. Subsurface stormflow has only been intercepted occasionally in a 120 m long trench, and often subsurface flow was not well correlated with stream signals, suggesting a disconnect between subsurface flow on the hillslopes and stream flow. We therefore used a hydrologic model to better understand which conditions promote the initiation of subsurface flow in this landscape, addressing following questions: Is there a threshold event size and soil moisture state for producing lateral subsurface flow? What role does the spatial pattern of depth to the impeding clay layer play for subsurface stormflow dynamics? We reproduced a section of a hillslope, for which high-resolution topographic data and depth to clay measurements were available, in the hydrologic model HYDRUS-3D. Soil hydraulic parameters were based on experimentally-derived data. The threshold analysis was first performed using hourly climate data records for 2009-2010 from the study site to drive the simulation. For this period also trench measurements of subsurface flow were available. In addition

  6. Surface and subsurface nitrate flow pathways on a watershed scale.

    PubMed

    Daughtry, C S; Gish, T J; Dulaney, W P; Walthall, C L; Kung, K J; McCarty, G W; Angier, J T; Buss, P

    2001-11-30

    Determining the interaction and impact of surface runoff and subsurface flow processes on the environment has been hindered by our inability to characterize subsurface soil structures on a watershed scale. Ground penetrating radar (GPR) data were collected and evaluated in determining subsurface hydrology at four small watersheds in Beltsville, MD. The watersheds have similar textures, organic matter contents, and yield distributions. Although the surface slope was greater on one of the watersheds, slope alone could not explain why it also had a nitrate runoff flux that was 18 times greater than the other three watersheds. Only with knowledge of the subsurface hydrology could the surface runoff differences be explained. The subsurface hydrology was developed by combining GPR and surface topography in a geographic information system. Discrete subsurface flow pathways were identified and confirmed with color infrared imagery, real-time soil moisture monitoring, and yield monitoring. The discrete subsurface flow patterns were also useful in understanding observed nitrate levels entering the riparian wetland and first order stream. This study demonstrated the impact that subsurface stratigraphy can have on water and nitrate (NO3-N) fluxes exiting agricultural lands, even when soil properties, yield distributions, and climate are similar. Reliable protocols for measuring subsurface fluxes of water and chemicals need to be developed.

  7. Plutonium Contamination Issues in Hanford Soils and Sediments: Discharges from the Z-Plant (PFP) Complex

    SciTech Connect

    Felmy, Andrew R.; Cantrell, Kirk J.; Conradson, Steven D.

    2010-08-23

    Beginning in 1945, weapons prod