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Sample records for anoxic marine sediment

  1. 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.

  2. Nitrogen losses in anoxic marine sediments driven by Thioploca-anammox bacterial consortia.

    PubMed

    Prokopenko, M G; Hirst, M B; De Brabandere, L; Lawrence, D J P; Berelson, W M; Granger, J; Chang, B X; Dawson, S; Crane, E J; Chong, L; Thamdrup, B; Townsend-Small, A; Sigman, D M

    2013-08-01

    Ninety per cent of marine organic matter burial occurs in continental margin sediments, where a substantial fraction of organic carbon escapes oxidation and enters long-term geologic storage within sedimentary rocks. In such environments, microbial metabolism is limited by the diffusive supply of electron acceptors. One strategy to optimize energy yields in a resource-limited habitat is symbiotic metabolite exchange among microbial associations. Thermodynamic and geochemical considerations indicate that microbial co-metabolisms are likely to play a critical part in sedimentary organic carbon cycling. Yet only one association, between methanotrophic archaea and sulphate-reducing bacteria, has been demonstrated in marine sediments in situ, and little is known of the role of microbial symbiotic interactions in other sedimentary biogeochemical cycles. Here we report in situ molecular and incubation-based evidence for a novel symbiotic consortium between two chemolithotrophic bacteria--anaerobic ammonium-oxidizing (anammox) bacteria and the nitrate-sequestering sulphur-oxidizing Thioploca species--in anoxic sediments of the Soledad basin at the Mexican Pacific margin. A mass balance of benthic solute fluxes and the corresponding nitrogen isotope composition of nitrate and ammonium fluxes indicate that anammox bacteria rely on Thioploca species for the supply of metabolic substrates and account for about 57 ± 21 per cent of the total benthic N2 production. We show that Thioploca-anammox symbiosis intensifies benthic fixed nitrogen losses in anoxic sediments, bypassing diffusion-imposed limitations by efficiently coupling the carbon, nitrogen and sulphur cycles. PMID:23925243

  3. Nitrogen losses in anoxic marine sediments driven by Thioploca-anammox bacterial consortia.

    PubMed

    Prokopenko, M G; Hirst, M B; De Brabandere, L; Lawrence, D J P; Berelson, W M; Granger, J; Chang, B X; Dawson, S; Crane, E J; Chong, L; Thamdrup, B; Townsend-Small, A; Sigman, D M

    2013-08-01

    Ninety per cent of marine organic matter burial occurs in continental margin sediments, where a substantial fraction of organic carbon escapes oxidation and enters long-term geologic storage within sedimentary rocks. In such environments, microbial metabolism is limited by the diffusive supply of electron acceptors. One strategy to optimize energy yields in a resource-limited habitat is symbiotic metabolite exchange among microbial associations. Thermodynamic and geochemical considerations indicate that microbial co-metabolisms are likely to play a critical part in sedimentary organic carbon cycling. Yet only one association, between methanotrophic archaea and sulphate-reducing bacteria, has been demonstrated in marine sediments in situ, and little is known of the role of microbial symbiotic interactions in other sedimentary biogeochemical cycles. Here we report in situ molecular and incubation-based evidence for a novel symbiotic consortium between two chemolithotrophic bacteria--anaerobic ammonium-oxidizing (anammox) bacteria and the nitrate-sequestering sulphur-oxidizing Thioploca species--in anoxic sediments of the Soledad basin at the Mexican Pacific margin. A mass balance of benthic solute fluxes and the corresponding nitrogen isotope composition of nitrate and ammonium fluxes indicate that anammox bacteria rely on Thioploca species for the supply of metabolic substrates and account for about 57 ± 21 per cent of the total benthic N2 production. We show that Thioploca-anammox symbiosis intensifies benthic fixed nitrogen losses in anoxic sediments, bypassing diffusion-imposed limitations by efficiently coupling the carbon, nitrogen and sulphur cycles.

  4. Marine silicate weathering in the anoxic sediment of the Ulleung Basin: Evidence and consequences

    NASA Astrophysics Data System (ADS)

    Kim, Ji-Hoon; Torres, Marta E.; Haley, Brian A.; Ryu, Jong-Sik; Park, Myong-Ho; Hong, Wei-Li; Choi, Jiyoung

    2016-08-01

    Marine silicate weathering (MSiW) in anoxic sediments has been recently shown to be a significant sink for CO2 generated by methanogenesis. Independently, the roles of clay dehydration (illitization) in producing water and driving upward fluid advection have been well established in deep marine sediments, but to date the K+ source required for the reaction has not been established. Here we present chemical and strontium isotope properties of pore fluids from seven cores in the Ulleung Basin, which show radiogenic 87Sr/86Sr values (up to ˜0.71045), very high alkalinity values (maximum ˜130 mM), and enrichment in H4SiO4, Na+, K+, and Mg2+, consistent with MSiW. This reaction consumes CO2, generates alkalinity, and acts as a K+ source for illitization; water released from MSiW-supported illitization drives upward fluid flow. Our results highlight the importance of MSiW along continental margins and its underappreciated role in carbon cycling, silicate diagenesis, and hydrogeology of marine systems.

  5. INTERACTION OF METALS AND ORGAINIC CARBON COLLOIDS IN ANOXIC INTERSTITIAL WATERS OF MARINE SEDIMENTS

    EPA Science Inventory

    Marine colloids are an important component of natural water geochemistry critical to the cycling, speciation and bioavailability of metals in marine sediments. In sediment, metals exist in three phases: particulate, colloidal and dissolved. Dissolved metal concentrations have bee...

  6. Factors that control the stable carbon isotopic composition of methane produced in an anoxic marine sediment

    NASA Technical Reports Server (NTRS)

    Alperin, M. J.; Blair, Neal E.; Albert, D. B.; Hoehler, T. M.; Martens, C. S.

    1993-01-01

    The carbon isotopic composition of methane produced in anoxic marine sediment is controlled by four factors: (1) the pathway of methane formation, (2) the isotopic composition of the methanogenic precursors, (3) the isotope fractionation factors for methane production, and (4) the isotope fractionation associated with methane oxidation. The importance of each factor was evaluated by monitoring stable carbon isotope ratios in methane produced by a sediment microcosm. Methane did not accumulate during the initial 42-day period when sediment contained sulfate, indicating little methane production from 'noncompetitive' substrates. Following sulfate depletion, methane accumulation proceeded in three distinct phases. First, CO2 reduction was the dominant methanogenic pathway and the isotopic composition of the methane produced ranged from -80 to -94 per thousand. The acetate concentration increased during this phase, suggesting that acetoclastic methanogenic bacteria were unable to keep pace with acetate production. Second, acetate fermentation became the dominant methanogenic pathway as bacteria responded to elevated acetate concentrations. The methane produced during this phase was progressively enriched in C-13, reaching a maximum delta(C-13) value of -42 per thousand. Third, the acetate pool experienced a precipitous decline from greater than 5 mM to less than 20 micro-M and methane production was again dominated by CO2 reduction. The delta(C-13) of methane produced during this final phase ranged from -46 to -58 per thousand. Methane oxidation concurrent with methane production was detected throughout the period of methane accumulation, at rates equivalent to 1 to 8 percent of the gross methane production rate. Thus methane oxidation was too slow to have significantly modified the isotopic signature of methane. A comparison of microcosm and field data suggests that similar microbial interactions may control seasonal variability in the isotopic composition of methane

  7. The isotopic composition of authigenic chromium in anoxic marine sediments: A case study from the Cariaco Basin

    NASA Astrophysics Data System (ADS)

    Reinhard, Christopher T.; Planavsky, Noah J.; Wang, Xiangli; Fischer, Woodward W.; Johnson, Thomas M.; Lyons, Timothy W.

    2014-12-01

    Chromium (Cr) isotopes are an emerging proxy for tracking redox processes at the Earth's surface. However, there has been limited exploration of the Cr isotope record of modern and recent marine sediments. The basic inorganic chemistry of Cr suggests that anoxic marine basins should factor prominently in the global Cr cycle and that sediments deposited within anoxic basins may offer a valuable Cr isotope archive throughout Earth's history. Here, we present δ53Cr data from sediments of the Cariaco Basin, Venezuela-a 'type' environment for large, perennially anoxic basins with a relatively strong hydrological connection to the global oceans. We document a marked positive shift in bulk δ53Cr values following the termination of the Last Glacial Maximum, followed by relative stasis. Based on a suite of independent redox proxies, this transition marks a switch from oxic to persistently anoxic and sulfidic (euxinic) depositional conditions within the basin. We find good agreement between two independent approaches toward estimating the δ53Cr composition of authigenic Cr in euxinic Cariaco Basin sediments and that these estimates are very similar to the δ53Cr composition of modern open Atlantic Ocean seawater. These data, together with considerations of reaction kinetics and mass balance within the Cariaco Basin, are consistent with the hypothesis that anoxic marine settings can serve as a chemical archive of first-order trends in seawater δ53Cr composition. Additionally, the Cariaco Basin data suggest that there has been secular stability in the average δ53Cr value of Atlantic seawater over the last ∼15 kyr.

  8. Jellyfish Lake, Palau: early diagenesis of organic matter in sediments of an anoxic marine lake

    USGS Publications Warehouse

    Orem, W.H.; Burnett, W.C.; Landing, W.M.; Lyons, W.B.; Showers, W.

    1991-01-01

    The major postdepositional change in the sedimentary organic matter is carbohydrate biodegradation. Lignin and aliphatic substances are preserved in the sediments. Dissolved organic matter in pore waters is primarily composed of carbohydrates, reflecting the degradation of sedimentary carbohydrates. Rate constants for organic carbon degradation and sulfate reduction in sediments of the lake are about 10?? lower than in other anoxic sediments. This may reflect the vascular plant source and partly degraded nature of the organic matter reaching the sediments of the lake. -from Authors

  9. Effects of prokaryotic diversity changes on hydrocarbon degradation rates and metal partitioning during bioremediation of contaminated anoxic marine sediments.

    PubMed

    Rocchetti, Laura; Beolchini, Francesca; Hallberg, Kevin B; Johnson, D Barrie; Dell'Anno, Antonio

    2012-08-01

    We investigated changes of prokaryotic diversity during bioremediation experiments carried out on anoxic marine sediments characterized by high hydrocarbon and metal content. Microcosms containing contaminated sediments were amended with lactose and acetate and incubated in anaerobic conditions up to 60 d at 20 or 35 °C. Microcosms displaying higher degradation efficiency of hydrocarbons were characterized by the dominance of Alphaproteobacteria and Methanosarcinales and the lack of gene sequences belonging to known hydrocarbonoclastic bacteria. Multivariate analyses support the hypothesis that Alphaproteobacteria are important for hydrocarbon degradation and highlight a potential synergistic effect of archaea and bacteria in changes of metal partitioning. Overall, these results point out that the identification of changes in the prokaryotic diversity during bioremediation of contaminated marine sediments is not only important for the improvement of bio-treatment performance towards hydrocarbons, but also for a better comprehension of changes occurring in metal partitioning which affect their mobility and toxicity.

  10. Methane production from bicarbonate and acetate in an anoxic marine sediment

    NASA Technical Reports Server (NTRS)

    Crill, P. M.; Martens, C. S.

    1986-01-01

    Methane production from C-14 labeled bicarbonate and acetate was measured over the top 28 cm of anoxic Cape Lookout Bight sediments during the summer of 1983. The depth distribution and magnitude of summed radioisotopically determined rates compare well with previous measurements of total methane production and the sediment-water methane flux. Methane production from CO2 reduction and acetate fermentation accounts for greater than 80 percent of the total production rate and sediment-water flux. Methane production from bicarbonate was found to occur in all depth intervals sampled except those in the top 2 cm, whereas significant methane production from acetate only occurred at depths below 10 cm where sulfate was exhausted. Acetate provided 20 to 29 percent of the measured methane production integrated over the top 30 cm of the sediments.

  11. Sedimentological, Magnetic and Geochemical Proxies for Holocene Climate Change and Paleoseismology from Marine Anoxic Inlet Sediments

    NASA Astrophysics Data System (ADS)

    Enkin, R. J.; Dallimore, A.; Baker, J.; Ivanochko, T.; Chang, A. S.

    2009-05-01

    Sediments deposited in anoxic basins are not bioturbated and thus hold high temporal resolution proxy recordings of climate and other physical controls. This paper focuses on the inner basin of Effingham Inlet on the west coast of Vancouver Island, Canada, a 120m deep fiord basin restricted from the open ocean by a 46m deep sill. Fifteen years of oceanographic monitoring have helped establish the physical and sedimentary processes at play. Freeze cores, piston cores, and especially the 40 m long MD02-2494 core hold a15 ka record of Late Pleistocene deglaciation, relative sea level change, Holocene climate and paleoseismology, revealed by sedimentological, magnetic and geochemical analysis. The age model is established using terrestrial 14C dates complemented by varve counting and paleomagnetic secular variation correlations. Annual laminations are formed of spring/summer diatom deposits following algal blooms and dominantly- winter deposits of clastics. These sediments provide proxies of Holocene weather with annual resolution. There are several episodes of rapid regime change from high seasonality warm climate to low seasonality wet-cold climate. Interspersed with the the annual laminations, there are two types of massive deposits: "homogenites" formed by remixing of suspended sediments by bottom-hugging currents, and "seismites" formed by mass wasting events associated with ground shaking. Magnetically, both the laminations and homogenites feature similar single-domain magnetic grains, while the seismites feature larger magnetic grains with multi-domain signatures, thus providing a simple tool for distinguishing the two visually similar deposit types. Homogenites, which result from La Nina-like oceanic conditions, first appear in core MD02- 2494 approximately 8 ka and have been increasing in frequency ever since.

  12. Seasonal C-13 variations of methane from an anoxic marine sediment

    NASA Technical Reports Server (NTRS)

    Blair, Neal; Desmarais, David S.; Martens, Christopher S.

    1985-01-01

    Recent analyses of glacial ice suggest that the atmospheric concentration of methane has doubled in the last several hundred years, presumably due to anthropogenic perturbations of the relevant biogeochemical cycles. In principal, carbon isotopic measurements of atmospheric methane would provide information concerning changes in the sources and sinks of methane. The isotopic composition of methane is dependent on the source of the methane carbon, the mechanism of methane synthesis, and the degree and mode of oxidation which the methane has experienced. Unfortunately, few carbon isotopic measurements of atmospheric variations have been reported, so conclusions about temporal isotopic variations cannot be made. Also, before isotopic measurements of atmospheric methane can be used to identify changes in methane isotopic composition from different sources must be obtained. Methane bubbles from the anoxic sediments of Cape Lookout Bight, NC exhibit seasonal C-13 variations. The C-13 values ranged from -58 in August to -64 in the winter months with the evolution of the C-13 enriched gas occurring during periods of peak methane production. Even though a few intramolecular C-13 measurements of the pore water acetate have been made (methyl group, -26 per mil; carbonyl, -6 per mil), it is not clear how the acetate fermentation pathway affects the methane C-13/C-12 composition.

  13. Jellyfish Lake, Palau: Regeneration of C, N, Si, and P in anoxic marine lake sediments

    USGS Publications Warehouse

    Lyons, W.B.; Lent, R.M.; Burnett, W.C.; Chin, P.; Landing, W.M.; Orem, W.H.; McArthur, J.M.

    1996-01-01

    Sediment cores from Jellyfish Lake were processed under an inert atmosphere and the pore waters extracted and analyzed for the following parameters: pH, titration alkalinity (TA), Cl-, H4SiO4, PO43-, NH4+, Ca2-, Mg2+, SO42-, and H2S. Additionally, in one set of pore-water samples (core 10), the ??13C of the ??CO2 was also determined. The TA, H4SiO4, PO43-, NH4+, and H2S increased with depth in the pore waters above anoxic bottom-water values. H2S values increased to 3.8 ??M. In one case, both H4SiO4 and PO43- concentrations increased to a maximum value and then decreased with depth, suggesting removal into solid phases. The H4SiO4 concentrations are equal to or greater than pore-water values observed in sediments underlying upwelling areas. PO43- concentrations are, in general, lower than pore-water values from terrigenous nearshore areas but higher than nearshore carbonate pore-water values from Florida Bay or Bermuda. The Ca2+, Cl-, and Mg2+: Cl- ratios show slight decreases in the top 15-20 cm, suggesting that authigenic carbonate may be forming. This suggestion is supported by the fact that the pore waters are saturated with respect to CaCO3 due to the very high TAs. The ??13C measurements of the pore-water ??CO2 are from a shorter core. These measurements reach their most negative concentration at 72 cm and then become slightly heavier. This change is accompanied by a decrease in TA, suggesting the onset of methanogenesis at this location in this core.

  14. Field and laboratory studies of methane oxidation in an anoxic marine sediment: Evidence for a methanogen-sulfate reducer consortium

    NASA Astrophysics Data System (ADS)

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

    1994-12-01

    Field and laboratory studies of anoxic sediments from Cape Lookout Bight, North Carolina, suggest that anaerobic methane oxidation is mediated by a consortium of methanogenic and sulfate-reducing bacteria. A seasonal survey of methane oxidation and CO2 reduction rates indicates that methane production was confined to sulfate-depleted sediments at all times of year, while methane oxidation occurred in two modes. In the summer, methane oxidation was confined to sulfate-depleted sediments and occurred at rates lower than those of CO2 reduction. In the winter, net methane oxidation occurred in an interval at the base of the sulfate-containing zone. Sediment incubation experiments suggest both methanogens and sulfate reducers were responsible for the observed methane oxidation. In one incubation experiment both modes of oxidation were partially inhibited by 2-bromoethanesulfonic acid (a specific inhibitor of methanogens). This evidence, along with the apparent confinement of methane oxidation to sulfate-depleted sediments in the summer, indicates that methanogenic bacteria are involved in methane oxidation. In a second incubation experiment, net methane oxidation was induced by adding sulfate to homogenized methanogenic sediments, suggesting that sulfate reducers also play a role in the process. We hypothesize that methanogens oxidize methane and produce hydrogen via a reversal of CO2 reduction. The hydrogen is efficiently removed and maintained at low concentrations by sulfate reducers. Pore water H2 concentrations in the sediment incubation experiments (while net methane oxidation was occurring) were low enough that methanogenic bacteria could derive sufficient energy for growth from the oxidation of methane. The methanogen-sulfate reducer consortium is consistent not only with the results of this study, but may also be a feasible mechanism for previously documented anaerobic methane oxidation in both freshwater and marine environments.

  15. Field and laboratory studies of methane oxidation in an anoxic marine sediment: Evidence for a methanogen-sulfate reducer consortium

    SciTech Connect

    Hoehler, T.M.; Alperin, M.J.; Albert, D.B.

    1994-12-01

    Field and laboratory studies of anoxic sediments from Cape Lookout Bight, North Carolina, suggest that anaerobic methane oxidation is mediated by a consortium of methanogenic and sulfate-reducing bacteria. A seasonal survey of methane oxidation and CO{sub 2} reduction rates indicates that methane production was confined to sulfate-depleted sediments at all times of year, while methane oxidation occurred in two modes. In the summer, methane oxidation was confined to sulfate-depleted sediments and occurred at rates lower than those of CO{sub 2} reduction. In the winter, net methane oxidation occurred in an interval at the base of the sulfate-containing zone. Sediment incubation experiments suggest both methanogens and sulfate reducers were responsible for the observed methane oxidation. In one incubation experiment both modes of oxidation were partially inhibited by 2-bromoethanesulfonic acid (a specific inhibitor of methanogens). This evidence, along with the apparent confinement of methane oxidation to sulfate-depleted sediments in the summer, indicates that methanogenic bacteria are involved in methane oxidation. In a second incubation experiment, net methane oxidation was induced by adding sulfate to homogenized methanogenic sediments, suggesting that sulfate reducers also a play a role in the process. We hypothesize that methanogens oxidize methane and produce hydrogen via a reversal of CO{sub 2} reduction. The hydrogen is efficiently removed and maintained at low concentrations by sulfate reducers. Pore water H{sub 2} concentrations in the sediment incubation experiments (while net methane oxidation was occurring) were low enough that methanogenic bacteria could derive sufficient energy for growth from the oxidation of methane. The methanogen-sulfate reducer consortium may also be a feasible mechanism for previously documented anaerobic methane oxidation in both freshwater and marine environments. 63 refs., 6 refs.

  16. Controls on the preservation of buried organic matter in an anoxic coastal marine sediment

    SciTech Connect

    Haddad, R.I. ); Martens, C.S. )

    1992-01-01

    Previous work detailing the carbon budget for the upper meter of sediments at Station A-1, Cap Lookout Bight, N.C., indicates that of the 165 [+-] 20 mol C/m[sup 2]y buried below the sediment-water interface, 71 [+-] 14% survives remineralization on a ten-year time scale. Whether this high degree of preservation is due to the nature of the system or to the nature of the organic matter (OM) itself is of considerable interest to geochemists interested in either the dynamics of global element cycling or the prediction of ancient deposition of hydrocarbon-prone organic facies. Organic geochemical measurements have been made to evaluate and compare the carbon budget in terms of the biochemically recognizable carbon fraction (BRC). Results from this study show that the BRC fraction accounts for < 30% of the TOC in the 0--5cm surface interval and that this decreases to 18 [+-] 8% by a depth of 100cm. In terms of carbon preservation, it appears that approximately 50% of the buried BRC fraction survives early diagenesis. Evaluation of the CHS fraction indicates that aside from some possible incorporation of labile biochemicals within the fulvic acids, elemental analysis and CP/MAS 13C-NMR results support a marine/algal/bacterial source for the bulk of the humic organic matter. Comparative microbial sulfate reduction studies employing independent manipulation of both the organic matter and sulfate oxidant concentrations were performed in order to evaluate the effect of inorganic oxidant availability on organic matter preservation. The authors conclude that while the buried organic matter is predominantly derived from microbially-reactive algal/bacterial sources, pre-depositional diagenetic processes effectively transform it into a microbial unreactive form.

  17. A carbon isotope mass balance for an anoxic marine sediment: Isotopic signatures of diagenesis

    NASA Technical Reports Server (NTRS)

    Boehme, Susan E.

    1993-01-01

    A carbon isotope mass balance was determined for the sediments of Cape Lookout Bight, NC to constrain the carbon budgets published previously. The diffusive, ebullitive and burial fluxes of sigma CO2 and CH4, as well as the carbon isotope signatures of these fluxes, were measured. The flux-weighted isotopic signature of the remineralized carbon (-18.9 plus or minus 2.7 per mil) agreed with the isotopic composition of the remineralized organic carbon determined from the particulate organic carbon (POC) delta(C-13) profiles (-19.2 plus or minus 0.2), verifying the flux and isotopic signature estimates. The measured delta(C-13) values of the sigma CO2 and CH4 diffusive fluxes were significantly different from those calculated from porewater gradients. The differences appear to be influenced by methane oxidation at the sediment-water interface, although other potential processes cannot be excluded. The isotope mass balance provides important information concerning the locations of potential diagenetic isotope effects. Specifically, the absence of downcore change in the delta(C-13) value of the POC fraction and the identical isotopic composition of the POC and the products of remineralization indicate that no isotopic fractionation is expressed during the initial breakdown of the POC, despite its isotopically heterogeneous composition.

  18. Oxygenation of anoxic sediments triggers hatching of zooplankton eggs.

    PubMed

    Broman, Elias; Brüsin, Martin; Dopson, Mark; Hylander, Samuel

    2015-10-22

    Many coastal marine systems have extensive areas with anoxic sediments and it is not well known how these conditions affect the benthic-pelagic coupling. Zooplankton lay their eggs in the pelagic zone, and some sink and lie dormant in the sediment, before hatched zooplankton return to the water column. In this study, we investigated how oxygenation of long-term anoxic sediments affects the hatching frequency of dormant zooplankton eggs. Anoxic sediments from the brackish Baltic Sea were sampled and incubated for 26 days with constant aeration whereby, the sediment surface and the overlying water were turned oxic. Newly hatched rotifers and copepod nauplii (juveniles) were observed after 5 and 8 days, respectively. Approximately 1.5 × 10(5) nauplii m(-2) emerged from sediment turned oxic compared with 0.02 × 10(5) m(-2) from controls maintained anoxic. This study demonstrated that re-oxygenation of anoxic sediments activated a large pool of buried zooplankton eggs, strengthening the benthic-pelagic coupling of the system. Modelling of the studied anoxic zone suggested that a substantial part of the pelagic copepod population can derive from hatching of dormant eggs. We suggest that this process should be included in future studies to understand population dynamics and carbon flows in marine pelagic systems.

  19. Effective bioremediation strategy for rapid in situ cleanup of anoxic marine sediments in mesocosm oil spill simulation

    PubMed Central

    Genovese, Maria; Crisafi, Francesca; Denaro, Renata; Cappello, Simone; Russo, Daniela; Calogero, Rosario; Santisi, Santina; Catalfamo, Maurizio; Modica, Alfonso; Smedile, Francesco; Genovese, Lucrezia; Golyshin, Peter N.; Giuliano, Laura; Yakimov, Michail M.

    2014-01-01

    The purpose of present study was the simulation of an oil spill accompanied by burial of significant amount of petroleum hydrocarbons (PHs) in coastal sediments. Approximately 1000 kg of sediments collected in Messina harbor were spiked with Bunker C furnace fuel oil (6500 ppm). The rapid consumption of oxygen by aerobic heterotrophs created highly reduced conditions in the sediments with subsequent recession of biodegradation rates. As follows, after 3 months of ageing, the anaerobic sediments did not exhibit any significant levels of biodegradation and more than 80% of added Bunker C fuel oil remained buried. Anaerobic microbial community exhibited a strong enrichment in sulfate-reducing PHs-degrading and PHs-associated Deltaproteobacteria. As an effective bioremediation strategy to clean up these contaminated sediments, we applied a Modular Slurry System (MSS) allowing the containment of sediments and their physical–chemical treatment, e.g., aeration. Aeration for 3 months has increased the removal of main PHs contaminants up to 98%. As revealed by CARD-FISH, qPCR, and 16S rRNA gene clone library analyses, addition of Bunker C fuel oil initially affected the activity of autochthonous aerobic obligate marine hydrocarbonoclastic bacteria (OMHCB), and after 1 month more than the third of microbial population was represented by Alcanivorax-, Cycloclasticus-, and Marinobacter-related organisms. In the end of the experiment, the microbial community composition has returned to a status typically observed in pristine marine ecosystems with no detectable OMHCB present. Eco-toxicological bioassay revealed that the toxicity of sediments after treatment was substantially decreased. Thus, our studies demonstrated that petroleum-contaminated anaerobic marine sediments could efficiently be cleaned through an in situ oxygenation which stimulates their self-cleaning potential due to reawakening of allochtonous aerobic OMHCB. PMID:24782850

  20. Apparent Minimum Free Energy Requirements for Methanogenic Archaea and Sulfate-Reducing Bacteria in an Anoxic Marine Sediment

    NASA Technical Reports Server (NTRS)

    Hoehler, Tori M.; Alperin, Marc J.; Albert, Daniel B.; Martens, Christopher S.; DeVincenzi, Don (Technical Monitor)

    2000-01-01

    Among the most fundamental constraints governing the distribution of microorganisms in the environment is the availability of chemical energy at biologically useful levels. To assess the minimum free energy yield that can support microbial metabolism in situ, we examined the thermodynamics of H2-consuming processes in anoxic sediments from Cape Lookout Bight, NC, USA. Depth distributions of H2 partial pressure, along with a suite of relevant concentration data, were determined in sediment cores collected in November (at 14.5 C) and August (at 27 C) and used to calculate free energy yields for methanogenesis and sulfate reduction. At both times of year, and for both processes, free energy yields gradually decreased (became less negative) with depth before reaching an apparent asymptote. Sulfate reducing bacteria exhibited an asymptote of -19.1 +/- 1.7 kj(mol SO4(2-)(sup -1) while methanogenic archaea were apparently supported by energy yields as small as -10.6 +/- 0.7 kj(mol CH4)(sup -1).

  1. Microbial sequestration of phosphorus in anoxic upwelling sediments

    NASA Astrophysics Data System (ADS)

    Goldhammer, Tobias; Brüchert, Volker; Ferdelman, Timothy G.; Zabel, Matthias

    2010-08-01

    Phosphorus is an essential nutrient for life. In the ocean, phosphorus burial regulates marine primary production. Phosphorus is removed from the ocean by sedimentation of organic matter, and the subsequent conversion of organic phosphorus to phosphate minerals such as apatite, and ultimately phosphorite deposits. Bacteria are thought to mediate these processes, but the mechanism of sequestration has remained unclear. Here, we present results from laboratory incubations in which we labelled organic-rich sediments from the Benguela upwelling system, Namibia, with a 33P-radiotracer, and tracked the fate of the phosphorus. We show that under both anoxic and oxic conditions, large sulphide-oxidizing bacteria accumulate 33P in their cells, and catalyse the nearly instantaneous conversion of phosphate to apatite. Apatite formation was greatest under anoxic conditions. Nutrient analyses of Namibian upwelling waters and sediments suggest that the rate of phosphate-to-apatite conversion beneath anoxic bottom waters exceeds the rate of phosphorus release during organic matter mineralization in the upper sediment layers. We suggest that bacterial apatite formation is a significant phosphorus sink under anoxic bottom-water conditions. Expanding oxygen minimum zones are projected in simulations of future climate change, potentially increasing sequestration of marine phosphate, and restricting marine productivity.

  2. Oxic and Anoxic Regions of Subseafloor Sediment

    NASA Astrophysics Data System (ADS)

    D'Hondt, S.; Pockalny, R. A.; Spivack, A. J.; Inagaki, F.; Murray, R. W.; Adhikari, R. R.; Gribsholt, B.; Kallmeyer, J.; McKinley, C. C.; Morono, Y.; Røy, H.; Sauvage, J.; Ziebis, W.

    2015-12-01

    Dissolved oxygen content defines two broad categories of subseafloor sediment. In areas with high rates of microbial respiration, most of the sediment column is anoxic and active anaerobic microbial communities are present for hundreds of meters or more below the seafloor. In these regions, O2 and aerobic communities penetrate only millimeters to centimeters into the sediment from the sediment-water interface. In some areas of active fluid flow through the underlying basalt, O2 may also penetrate meters upward into the sediment from the basalt. In areas with low sedimentary respiration, O2 and aerobic communities penetrate tens of meters downward from the seafloor and may persist throughout the entire sediment column. IODP Expedition 329 showed that microbial cells and aerobic respiration persist through the entire sediment sequence (to depths of at least 75 meters below seafloor) in the South Pacific Gyre. Extrapolating from these results and a global relationship of O2 penetration depth to sedimentation rate and sediment thickness, we suggest that oxygen and aerobic communities occur throughout the entire sediment sequence in 15-44% of the Pacific and 9-37% of the global seafloor. Subduction of sediment from largely anoxic regions and subduction of sediment and basalt from fully oxic regions are respectively sources of reduced and oxidized material to the mantle. The balance between oxic and anoxic regions has presumably changed considerably throughout Earth history. Regions with largely anoxic sediment and regions with fully oxic sediment present fundamentally different opportunities for understanding of (i) paleoceanographic history and (ii) the nature of microbial life under extreme energy limitations.

  3. 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

  4. Denitrification in anoxic sediments supported by biological nitrate transport

    NASA Astrophysics Data System (ADS)

    Prokopenko, M. G.; Sigman, D. M.; Berelson, W. M.; Hammond, D. E.; Barnett, B.; Chong, L.; Townsend-Small, A.

    2011-11-01

    Biologically available nitrogen (fixed N) is removed from the oceans by metabolic conversion of inorganic N forms (nitrate and ammonium) to N 2 gas. Much of this removal occurs in marine sediments, where reaction rates are thought to be limited by diffusion. We measured the concentration and isotopic composition of major dissolved nitrogen species in anoxic sediments off the coast of California. At depths below the diffusive penetration of nitrate, we found evidence of a large nitrate pool transported into the sediments by motile microorganisms. A ˜20‰ enrichment in 15N and 18O of this biologically transported nitrate over bottom water values and elevated [N 2] and δ 15N-N 2 at depth indicate that this nitrate is consumed by enzymatic redox reactions with the production of N 2 as the end product. Elevated N 2O concentrations in pore waters below the nitrate diffusion depth confirm that these reactions include the denitrification pathway. A data-constrained model shows that at least 31% of the total N 2 production in anoxic sediments is linked to nitrate bio-transport. Under suboxic/anoxic regimes, this nitrate bio-transport augments diffusive transport, thus increasing benthic fixed nitrogen losses and the reducing burial efficiency of sedimentary organic matter.

  5. Anoxic marine lakes - an analogue environment for insular phosphorite formation

    SciTech Connect

    Burnett, W.C. )

    1990-06-01

    Hundreds of islands in the tropical Pacific Ocean contain phosphate deposits ranging from inconsequential to economically significant in size. Although many of these deposits clearly have formed by the interaction of avian guano with underlying limestone, some display evidence of having developed within an aqueous environment. Several of the emergent carbonate islands in the southern part of Palau contain phosphate deposits that the authors speculate formed in anoxic marine lakes, similar to those which still occur on a few of these islands. Lake water, sediments, and sediment pore waters from Jellyfish Lake, on the island of Eil Malk in Palau, were analyzed during an expedition in 1987. The results of this investigation supported, but did not provide, conclusive evidence of our hypothesis. Pore water profiles of phosphate and fluoride confirmed precipitation of carbonate fluorapatite. However, the extremely high bulk sediment accumulation rate, driven by the high biological productivity of the surface waters of the lake, dilutes authigenic phosphate to low levels. They have refined their original proposal to suggest that phosphate deposits may form either by: (1) subaerial weathering and concentration of phosphatic sediments after these lakes disappear; or (2) interaction of phosphate-enriched sediment pore solutions with limestone at the underlying contact. Another expedition to test these concepts is being planned.

  6. Are Iron-Phosphate Minerals a Sink for Phosphorus in Anoxic Black Sea Sediments?

    PubMed Central

    Dijkstra, Nikki; Kraal, Peter; Kuypers, Marcel M. M.; Schnetger, Bernhard; Slomp, Caroline P.

    2014-01-01

    Phosphorus (P) is a key nutrient for marine organisms. The only long-term removal pathway for P in the marine realm is burial in sediments. Iron (Fe) bound P accounts for a significant proportion of this burial at the global scale. In sediments underlying anoxic bottom waters, burial of Fe-bound P is generally assumed to be negligible because of reductive dissolution of Fe(III) (oxyhydr)oxides and release of the associated P. However, recent work suggests that Fe-bound P is an important burial phase in euxinic (i.e. anoxic and sulfidic) basin sediments in the Baltic Sea. In this study, we investigate the role of Fe-bound P as a potential sink for P in Black Sea sediments overlain by oxic and euxinic bottom waters. Sequential P extractions performed on sediments from six multicores along two shelf-to-basin transects provide evidence for the burial of Fe-bound P at all sites, including those in the euxinic deep basin. In the latter sediments, Fe-bound P accounts for more than 20% of the total sedimentary P pool. We suggest that this P is present in the form of reduced Fe-P minerals. We hypothesize that these minerals may be formed as inclusions in sulfur-disproportionating Deltaproteobacteria. Further research is required to elucidate the exact mineral form and formation mechanism of this P burial phase, as well as its role as a sink for P in sulfide-rich marine sediments. PMID:24988389

  7. Are iron-phosphate minerals a sink for phosphorus in anoxic Black Sea sediments?

    PubMed

    Dijkstra, Nikki; Kraal, Peter; Kuypers, Marcel M M; Schnetger, Bernhard; Slomp, Caroline P

    2014-01-01

    Phosphorus (P) is a key nutrient for marine organisms. The only long-term removal pathway for P in the marine realm is burial in sediments. Iron (Fe) bound P accounts for a significant proportion of this burial at the global scale. In sediments underlying anoxic bottom waters, burial of Fe-bound P is generally assumed to be negligible because of reductive dissolution of Fe(III) (oxyhydr)oxides and release of the associated P. However, recent work suggests that Fe-bound P is an important burial phase in euxinic (i.e. anoxic and sulfidic) basin sediments in the Baltic Sea. In this study, we investigate the role of Fe-bound P as a potential sink for P in Black Sea sediments overlain by oxic and euxinic bottom waters. Sequential P extractions performed on sediments from six multicores along two shelf-to-basin transects provide evidence for the burial of Fe-bound P at all sites, including those in the euxinic deep basin. In the latter sediments, Fe-bound P accounts for more than 20% of the total sedimentary P pool. We suggest that this P is present in the form of reduced Fe-P minerals. We hypothesize that these minerals may be formed as inclusions in sulfur-disproportionating Deltaproteobacteria. Further research is required to elucidate the exact mineral form and formation mechanism of this P burial phase, as well as its role as a sink for P in sulfide-rich marine sediments.

  8. Arrest of transcription following anoxic exposure in a marine mollusc.

    PubMed

    Larade, Kevin; Storey, Kenneth B

    2007-09-01

    The intertidal marine snail, Littorina littorea, is an anoxia tolerant species that endures long-term oxygen deprivation using a suite of compensatory metabolic adaptations that includes overall metabolic rate depression. Nuclear run-off assays were used to quantify the relative rates of mRNA transcription in nuclear extracts from hepatopancreas of aerobic and anoxic snails. Total [(32)P]-UTP incorporation into RNA by nuclei from 48 h anoxic snails ranged from 42 to 50% of that observed for nuclei from normoxic snails. When this data is transformed with respect to incubation time, the rate of [(32)P]-UTP incorporation by nuclei from 48 h anoxic snails showed a decrease of 68% as compared with the normoxic level. Examination of selected expressed sequence tags also showed an overall decrease in mRNA transcription levels in samples derived from anoxic nuclei as compared with normoxic nuclei. Control of ribosomal translation was also examined by assessing the levels of the eukaryotic initiation factors eIF-2alpha and eIF-4E and the eukaryotic elongation factor-1gamma (eEF-1gamma). Levels of eIF-4E and eEF-1gamma did not change between aerobic and anoxic states, but the amount of phosphorylated inactive eIF-2alpha rose strongly under anoxic conditions indicating that control of this factor is key to suppressing protein translation in anoxic snails. Since gene transcription is an ATP expensive process in cells, suppression of transcription to minimum levels provides substantial energy savings for the hepatopancreas, and the organism as a whole, under anoxic conditions. PMID:17503005

  9. Chlorofluorocarbon-11 removal in anoxic marine waters

    NASA Astrophysics Data System (ADS)

    Bullister, John L.; Lee, Bing-Sun

    Measurements of the chlorofluorocarbons CCl3F (F-11) and CCl2F2 (F-12) made in the subsurface anoxic zones of the Black Sea and Saanich Inlet, B.C., Canada show a pronounced depletion of dissolved F-11. These zones are strongly reducing and are characterized by the absence of dissolved nitrate (NO3-) and the presence of hydrogen sulfide (H2S). Models incorporating the atmospheric input histories of these CFCs and the observed distributions are used to estimate residence times for water in these zones and first order in-situ removal rates for F-11. In contrast, measurements in the mid-depth low-oxygen zone of the eastern Pacific (where NO3- is present and H2S is below detection limits) do not show evidence of similar rapid F-11 removal.

  10. Chlorofluorocarbon-11 removal in anoxic marine waters

    SciTech Connect

    Bullister, J.L.; Lee, B.S.

    1995-07-15

    Measurements of the chlorofluorocarbons CCl{sub 3}F (F-11) and CCl{sub 2}F{sub 2}(F-12) made in the subsurface anoxic zones of the Black Sea and Saanich Inlet, B.C., Canada show a pronounced depletion of dissolved F-11. These zones are strongly reducing and are characterized by the absence of dissolved nitrate (NO{sub 3}{sup {minus}}) and the presence of hydrogen sulfide (H{sub 2}S). Models incorporating the atmospheric input histories of these CFCs and the observed distributions are used to estimate residence times for water in these zones and first order in-situ removal rates for F-11. In contrast, measurements in the mid-depth low-oxygen zone of the eastern Pacific (where NO{sub 3}{sup {minus}} is present and H{sub 2}S is below detection limits) do not show evidence of similar rapid F-11 removal. 22 refs., 3 figs., 1 tab.

  11. Microbiological reduction of Sb(V) in anoxic freshwater sediments

    USGS Publications Warehouse

    Oremland, Ronald S.; Kulp, Thomas R.; Miller, Laurence G.; Braiotta, Franco; Webb, Samuel M.; Kocar, Benjamin D; Blum, Jodi S.

    2013-01-01

    Microbiological reduction of millimolar concentrations of Sb(V) to Sb(III) was observed in anoxic sediments from two freshwater settings: (1) a Sb- and As-contaminated mine site (Stibnite Mine) in central Idaho and 2) an uncontaminated suburban lake (Searsville Lake) in the San Francisco Bay Area. Rates of Sb(V) reduction in anoxic sediment microcosms and enrichment cultures were enhanced by amendment with lactate or acetate as electron donors but not by H2, and no reduction occurred in sterilized controls. Addition of 2-14C-acetate to Stibnite Mine microcosms resulted in the production of 14CO2 coupled to Sb(V) reduction, suggesting that this process proceeds by a dissimilatory respiratory pathway in those sediments. Antimony(V) reduction in Searsville Lake sediments was not coupled to acetate mineralization and may be associated with Sb-resistance. The microcosms and enrichment cultures also reduced sulfate, and the precipitation of insoluble Sb(III)-sulfide complexes was a major sink for reduced Sb. The reduction of Sb(V) by Stibnite Mine sediments was inhibited by As(V), suggesting that As(V) is a preferred electron acceptor for the indigenous community. These findings indicate a novel pathway for anaerobic microbiological respiration and suggest that communities capable of reducing high concentrations of Sb(V) commonly occur naturally in the environment.

  12. Microbiological reduction of Sb(V) in anoxic freshwater sediments.

    PubMed

    Kulp, Thomas R; Miller, Laurence G; Braiotta, Franco; Webb, Samuel M; Kocar, Benjamin D; Blum, Jodi S; Oremland, Ronald S

    2014-01-01

    Microbiological reduction of millimolar concentrations of Sb(V) to Sb(III) was observed in anoxic sediments from two freshwater settings: (1) a Sb- and As-contaminated mine site (Stibnite Mine) in central Idaho and 2) an uncontaminated suburban lake (Searsville Lake) in the San Francisco Bay Area. Rates of Sb(V) reduction in anoxic sediment microcosms and enrichment cultures were enhanced by amendment with lactate or acetate as electron donors but not by H2, and no reduction occurred in sterilized controls. Addition of 2-(14)C-acetate to Stibnite Mine microcosms resulted in the production of (14)CO2 coupled to Sb(V) reduction, suggesting that this process proceeds by a dissimilatory respiratory pathway in those sediments. Antimony(V) reduction in Searsville Lake sediments was not coupled to acetate mineralization and may be associated with Sb-resistance. The microcosms and enrichment cultures also reduced sulfate, and the precipitation of insoluble Sb(III)-sulfide complexes was a major sink for reduced Sb. The reduction of Sb(V) by Stibnite Mine sediments was inhibited by As(V), suggesting that As(V) is a preferred electron acceptor for the indigenous community. These findings indicate a novel pathway for anaerobic microbiological respiration and suggest that communities capable of reducing high concentrations of Sb(V) commonly occur naturally in the environment.

  13. Investigating phosphorus uptake in anoxic and sulfidic surface sediments with 33P radiotracer experiments

    NASA Astrophysics Data System (ADS)

    Dijkstra, Nikki; Kraal, Peter; Gonzalez, Santiago; Slomp, Caroline

    2016-04-01

    Phosphorus (P) is a key nutrient for marine organisms. Enhanced P availability in the water column can fuel algal blooms and the development of bottom water anoxia. Recently, it was suggested that micro-organisms in sediments overlain by anoxic and sulfidic bottom waters might take up dissolved P and form Fe(II)-P minerals, thereby enhancing P removal. In this study, we investigated the uptake of P in surface sediments with 33P radiotracer experiments. The sediments were recovered from the anoxic and sulfidic deep basin of the Black Sea and, for comparison, from the adjacent oxic shelf. Results suggest a very fast sedimentary uptake of 33P at all sites but in particular for sediments from the oxic shelf. At all sites, most 33P was sequestered in the citrate-dithionite-bicarbonate-(CDB)-extractable sediment P fraction. No significant differences with abiotic controls were observed, implying that micro-organisms were not directly involved in the P uptake. Whereas 33P uptake by the oxic shelf sediment was likely controlled by sorption of 33P to iron(Fe)-(oxyhydr)oxides, the nature of the CDB-extractable P fraction in the deep basin sediments remains unclear. We discuss whether authigenic formation of Fe(II)-P minerals or fast adsorption of P to calcites may explain our findings.

  14. The carbon isotope biogeochemistry of methane production in anoxic sediments. 1: Field observations

    NASA Technical Reports Server (NTRS)

    Blair, Neal E.; Boehme, Susan E.; Carter, W. Dale, Jr.

    1993-01-01

    The natural abundance C-13/C-12 ratio of methane from anoxic marine and freshwater sediments in temperate climates varies seasonally. Carbon isotopic measurements of the methanogenic precursors, acetate and dissolved inorganic carbon, from the marine sediments of Cape Lookout Bight, North Carolina were used to determine the sources of the seasonal variations at that site. Movement of the methanogenic zone over an isotopic gradient within the dissolved CO2 pool appears to be the dominant control of the methane C-13/C-12 ratio from February to June. The onset of acetoclastic methane-production is a second important controlling process during mid-summer. An apparent temperature dependence on the fractionation factor for CO2-reduction may have a significant influence on the isotopic composition of methane throughout the year.

  15. Chromium isotope composition of reducing and anoxic sediments from the Peru Margin and Cariaco Basin

    NASA Astrophysics Data System (ADS)

    Gueguen, B.; Planavsky, N.; Wang, X.; Algeo, T. J.; Peterson, L. C.; Reinhard, C. T.

    2014-12-01

    Chromium isotope systematics in marine sediments are now being used as a new redox proxy of the modern and ancient Earth's surface. Chromium is primarily delivered to the oceans by riverine inputs through weathering of Cr(III)-rich minerals present in the continental crust and oxidation of insoluble Cr(III) to soluble Cr(VI) species. Since oxidation-reduction reactions fractionate Cr isotopes whereby oxidized Cr(VI) species are preferentially enriched in heavy Cr isotopes, the Cr isotope composition of marine sediments may be useful tracers of redox conditions at the Earth's surface through geological time. Chromium is quantitatively removed in organic-rich sediments where reducing conditions prevail and promote reduction of Cr(VI) to Cr(III), and thus, these sediments should capture the ambient seawater Cr isotope composition. However, the isotopic composition of modern organic-rich sediments is poorly documented so far, and this step is essential for further modeling the global oceanic Cr isotope mass balance and assessing the effects of sedimentation and post-depositional processes on the marine Cr isotopes archive. In this study, we have characterized modern marine organic-rich sediments for their Cr isotope composition (δ53/52Cr) from two different settings, the Peru margin upwelling zone and the anoxic Cariaco Basin (Venezuela). Chromium isotopes were measured on a MC-ICP-MS (Nu Plasma) using a double-spike correction method. The authigenic fraction of shallow samples from the Peru margin sedimentary sequence with a high Total Organic Carbon (TOC) content (>10 wt%) yield an average δ53/52Crauthigenic value of +0.67 ±0.05 ‰ (2sd). However, although this value is close to the seawater value (Atlantic Ocean) and to Cariaco basin sediments (~ +0.6 ‰), reducing sediments from the Peru margin are on average isotopically slightly heavier, especially in samples having a low authigenic fraction and a low TOC content (δ53/52Crauthigenic values up to +1.30

  16. H2 cycling and microbial bioenergetics in anoxic sediments

    NASA Technical Reports Server (NTRS)

    Hoehler, Tori M.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    The simple biochemistry of H2 is central to a large number of microbial processes, affecting the interaction of organisms with each other and with the environment. In anoxic sediments, the great majority of microbial redox processes involve H2 as a reactant, product, or potential by-product, and the thermodynamics of these processes are thus highly sensitive to fluctuations in environmental H2 concentrations. In turn, H2 concentrations are controlled by the activity of H2-consuming microorganisms, which efficiently utilize this substrate down to levels which correspond to their bioenergetic limitations. Consequently, any environmental change which impacts the thermodynamics of H2-consuming organisms is mirrored by a corresponding change in H2 concentrations. This phenomenon is illustrated in anoxic sediments from Cape Lookout Bight, NC, USA: H2 concentrations are controlled by a suite of environmental parameters (e.g., temperature, sulfate concentrations) in a fashion which can be quantitatively described by a simple thermodynamic model. These findings allow us to calculate the apparent minimum quantity of biologically useful energy in situ. We find that sulfate reducing bacteria are not active at energy yields below -18 kJ per mole sulfate, while methanogenic archaea exhibit a minimum close to -10 kJ per mole methane.

  17. Methane production and simultaneous sulphate reduction in anoxic, salt marsh sediments

    USGS Publications Warehouse

    Oremland, R.S.; Marsh, L.M.; Polcin, S.

    1982-01-01

    It has been generally believed that sulphate reduction precludes methane generation during diagenesis of anoxic sediments1,2. Because most biogenic methane formed in nature is thought to derive either from acetate cleavage or by hydrogen reduction of carbon dioxide3-6, the removal of these compounds by the energetically more efficient sulphate-reducing bacteria can impose a substrate limitation on methanogenic bacteria 7-9. However, two known species of methanogens, Methanosarcina barkeri and Methanococcus mazei, can grow on and produce methane from methanol and methylated amines10-13. In addition, these compounds stimulate methane production by bacterial enrichments from the rumen11,14 and aquatic muds13,14. Methanol can enter anaerobic food webs through bacterial degradation of lignins15 or pectin16, and methylated amines can be produced either from decomposition of substances like choline, creatine and betaine13,14 or by bacterial reduction of trimethylamine oxide17, a common metabolite and excretory product of marine animals. However, the relative importance of methanol and methylated amines as precursors of methane in sediments has not been previously examined. We now report that methanol and trimethylamine are important substrates for methanogenic bacteria in salt marsh sediments and that these compounds may account for the bulk of methane produced therein. Furthermore, because these compounds do not stimulate sulphate reduction, methanogenesis and sulphate reduction can operate concurrently in sulphate-containing anoxic sediments. ?? 1982 Nature Publishing Group.

  18. ENANTIOSELECTIVE MICROBIAL TRANSFORMATION OF THE PHENYLPYRAZOLE INSECTICIDE FIPRONIL IN ANOXIC SEDIMENTS

    EPA Science Inventory

    Fipronil, a chiral insecticide, was biotransformed initially to fipronil sulfide in anoxic sediment slurries following a short lag period. Sediment slurries characterized as either sulfidogenic or methanogenic transformed fipronil with half-lives of approximately 35 and 40 days, ...

  19. Sulfur diagenesis in marine sediments

    NASA Technical Reports Server (NTRS)

    Goldhaber, M.

    1985-01-01

    Bacterial sulfate reduction occurs in all marine sediments that contain organic matter. Aqueous sulfide (HS-, H2S), one of the initial products of bacterial sulfide reduction, is extremely reactive with iron bearing minerals: sulfur is fixed into sediments as iron sulfide (first FeS and then Fe2S2). A working definition is given of sulfur diagenesis in marine sediments. Controls and consequences of sulfate reduction rates in marine sediments are examined.

  20. Enhanced carbon loss from anoxic lake sediment through diffusion of dissolved organic carbon

    NASA Astrophysics Data System (ADS)

    Peter, Simone; Isidorova, Anastasija; Sobek, Sebastian

    2016-07-01

    Lakes are highly relevant players in the global carbon cycle as they can store large amounts of organic carbon (OC) in sediments, thereby removing OC from the actively cycling pool. However, sediment OC can be released to pore water under anoxic conditions and diffuse into the water column. In carbon budgets of lake ecosystems, this potential OC loss pathway from sediments is generally disregarded. Combining field observations and incubation experiments, we quantitatively investigated dissolved OC (DOC) diffusion from sediments into anoxic water of a boreal lake. We observed substantial increases of bottom water DOC (26% in situ, 16% incubation), translating into a DOC flux from the sediment that was comparable to anoxic sediment respiration (3.3 versus 5.1 mmol m-2 d-1). Optical characterization indicated that colored and aromatic DOC was preferentially released. Reactivity assays showed that DOC released from anoxic sediment enhanced water column respiration and flocculation in reoxygenated water. Upon water oxygenation, flocculation was the most important loss pathway removing ~77% of released DOC, but the remaining ~23% was mineralized, constituting a pathway of permanent loss of sediment OC. DOC diffusion from lake sediment during anoxia and subsequent mineralization in oxic water during mixing increases overall OC loss from anoxic sediments by ~15%. This study enlarges our understanding of lake ecosystems by showing that under anoxic conditions significant amounts of DOC can be released from OC stored in sediments and enter the active aquatic carbon cycle again.

  1. Benthic protists and fungi of Mediterranean deep hypsersaline anoxic basin redoxcline sediments

    PubMed Central

    Bernhard, Joan M.; Kormas, Konstantinos; Pachiadaki, Maria G.; Rocke, Emma; Beaudoin, David J.; Morrison, Colin; Visscher, Pieter T.; Cobban, Alec; Starczak, Victoria R.; Edgcomb, Virginia P.

    2014-01-01

    Some of the most extreme marine habitats known are the Mediterranean deep hypersaline anoxic basins (DHABs; water depth ∼3500 m). Brines of DHABs are nearly saturated with salt, leading many to suspect they are uninhabitable for eukaryotes. While diverse bacterial and protistan communities are reported from some DHAB water-column haloclines and brines, the existence and activity of benthic DHAB protists have rarely been explored. Here, we report findings regarding protists and fungi recovered from sediments of three DHAB (Discovery, Urania, L’ Atalante) haloclines, and compare these to communities from sediments underlying normoxic waters of typical Mediterranean salinity. Halocline sediments, where the redoxcline impinges the seafloor, were studied from all three DHABs. Microscopic cell counts suggested that halocline sediments supported denser protist populations than those in adjacent control sediments. Pyrosequencing analysis based on ribosomal RNA detected eukaryotic ribotypes in the halocline sediments from each of the three DHABs, most of which were fungi. Sequences affiliated with Ustilaginomycotina Basidiomycota were the most abundant eukaryotic signatures detected. Benthic communities in these DHABs appeared to differ, as expected, due to differing brine chemistries. Microscopy indicated that only a low proportion of protists appeared to bear associated putative symbionts. In a considerable number of cases, when prokaryotes were associated with a protist, DAPI staining did not reveal presence of any nuclei, suggesting that at least some protists were carcasses inhabited by prokaryotic scavengers. PMID:25452749

  2. Benthic protists and fungi of Mediterranean deep hypsersaline anoxic basin redoxcline sediments.

    PubMed

    Bernhard, Joan M; Kormas, Konstantinos; Pachiadaki, Maria G; Rocke, Emma; Beaudoin, David J; Morrison, Colin; Visscher, Pieter T; Cobban, Alec; Starczak, Victoria R; Edgcomb, Virginia P

    2014-01-01

    Some of the most extreme marine habitats known are the Mediterranean deep hypersaline anoxic basins (DHABs; water depth ∼3500 m). Brines of DHABs are nearly saturated with salt, leading many to suspect they are uninhabitable for eukaryotes. While diverse bacterial and protistan communities are reported from some DHAB water-column haloclines and brines, the existence and activity of benthic DHAB protists have rarely been explored. Here, we report findings regarding protists and fungi recovered from sediments of three DHAB (Discovery, Urania, L' Atalante) haloclines, and compare these to communities from sediments underlying normoxic waters of typical Mediterranean salinity. Halocline sediments, where the redoxcline impinges the seafloor, were studied from all three DHABs. Microscopic cell counts suggested that halocline sediments supported denser protist populations than those in adjacent control sediments. Pyrosequencing analysis based on ribosomal RNA detected eukaryotic ribotypes in the halocline sediments from each of the three DHABs, most of which were fungi. Sequences affiliated with Ustilaginomycotina Basidiomycota were the most abundant eukaryotic signatures detected. Benthic communities in these DHABs appeared to differ, as expected, due to differing brine chemistries. Microscopy indicated that only a low proportion of protists appeared to bear associated putative symbionts. In a considerable number of cases, when prokaryotes were associated with a protist, DAPI staining did not reveal presence of any nuclei, suggesting that at least some protists were carcasses inhabited by prokaryotic scavengers.

  3. Benthic protists and fungi of Mediterranean deep hypsersaline anoxic basin redoxcline sediments.

    PubMed

    Bernhard, Joan M; Kormas, Konstantinos; Pachiadaki, Maria G; Rocke, Emma; Beaudoin, David J; Morrison, Colin; Visscher, Pieter T; Cobban, Alec; Starczak, Victoria R; Edgcomb, Virginia P

    2014-01-01

    Some of the most extreme marine habitats known are the Mediterranean deep hypersaline anoxic basins (DHABs; water depth ∼3500 m). Brines of DHABs are nearly saturated with salt, leading many to suspect they are uninhabitable for eukaryotes. While diverse bacterial and protistan communities are reported from some DHAB water-column haloclines and brines, the existence and activity of benthic DHAB protists have rarely been explored. Here, we report findings regarding protists and fungi recovered from sediments of three DHAB (Discovery, Urania, L' Atalante) haloclines, and compare these to communities from sediments underlying normoxic waters of typical Mediterranean salinity. Halocline sediments, where the redoxcline impinges the seafloor, were studied from all three DHABs. Microscopic cell counts suggested that halocline sediments supported denser protist populations than those in adjacent control sediments. Pyrosequencing analysis based on ribosomal RNA detected eukaryotic ribotypes in the halocline sediments from each of the three DHABs, most of which were fungi. Sequences affiliated with Ustilaginomycotina Basidiomycota were the most abundant eukaryotic signatures detected. Benthic communities in these DHABs appeared to differ, as expected, due to differing brine chemistries. Microscopy indicated that only a low proportion of protists appeared to bear associated putative symbionts. In a considerable number of cases, when prokaryotes were associated with a protist, DAPI staining did not reveal presence of any nuclei, suggesting that at least some protists were carcasses inhabited by prokaryotic scavengers. PMID:25452749

  4. Predictive isotopic biogeochemistry: hydrocarbons from anoxic marine basins

    NASA Technical Reports Server (NTRS)

    Freeman, K. H.; Wakeham, S. G.; Hayes, J. M.

    1994-01-01

    Carbon isotopic compositions were determined for individual hydrocarbons in water column and sediment samples from the Cariaco Trench and Black Sea. In order to identify hydrocarbons derived from phytoplankton, the isotopic compositions expected for biomass of autotrophic organisms living in surface waters of both localities were calculated based on the concentrations of CO2(aq) and the isotopic compositions of dissolved inorganic carbon. These calculated values are compared to measured delta values for particulate organic carbon and for individual hydrocarbon compounds. Specifically, we find that lycopane is probably derived from phytoplankton and that diploptene is derived from the lipids of chemoautotrophs living above the oxic/anoxic boundary. Three acyclic isoprenoids that have been considered markers for methanogens, pentamethyleicosane and two hydrogenated squalenes, have different delta values and apparently do not derive from a common source. Based on the concentration profiles and isotopic compositions, the C31 and C33 n-alkanes and n-alkenes have a similar source, and both may have a planktonic origin. If so, previously assigned terrestrial origins of organic matter in some Black Sea sediments may be erroneous.

  5. Minimum Energy Requirements for Sustained Microbial Activity in Anoxic Sediments

    NASA Technical Reports Server (NTRS)

    Hoehler, Tori M.; Alperin, Marc J.; Albert, Daniel B.; Martens, Christoper S.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Currently understood mechanisms of biochemical energy conservation dictate that, in order to be biologically useful, energy must be available to organisms in "quanta" equal to, at minimum one-third to one-fifth of the energy required to synthesize ATP in vivo. The existence of this biological energy quantum means that a significant fraction of the chemical amp on Earth cannot be used to drive biological productivity, and places a fundamental thermodynamic constraint on the origins, evolution, and distribution of life. We examined the energy requirements of intact microbial assemblages in anoxic sediments from Cape Lookout Bight, NC, USA, using dissolved hydrogen concentrations as a non-invasive probe. In this system, the thermodynamics of metabolic processes occurring inside microbial cells is reflected quantitatively by H2 concentrations measured outside those cells. We find that methanogenic archaea are supported by energy yields as small as 10 kJ per mol, about half the quantity calculated from studies of microorganisms in culture. This finding implies that a significantly broader range of geologic and chemical niches might be exploited by microorganisms than would otherwise be expected.

  6. Metatranscriptomic insights into polyphosphate metabolism in marine sediments.

    PubMed

    Jones, Daniel S; Flood, Beverly E; Bailey, Jake V

    2016-04-01

    Microorganisms can influence inorganic phosphate (Pi) in pore waters, and thus the saturation state of phosphatic minerals, by accumulating and hydrolyzing intracellular polyphosphate (poly-P). Here we used comparative metatranscriptomics to explore microbial poly-P utilization in marine sediments. Sulfidic marine sediments from methane seeps near Barbados and from the Santa Barbara Basin (SBB) oxygen minimum zone were incubated under oxic and anoxic sulfidic conditions. Pi was sequestered under oxic conditions and liberated under anoxic conditions. Transcripts homologous to poly-P kinase type 2 (ppk2) were 6-22 × more abundant in metatranscriptomes from the anoxic incubations, suggesting that reversible poly-P degradation by Ppk2 may be an important metabolic response to anoxia by marine microorganisms. Overall, diverse taxa differentially expressed homologues of genes for poly-P degradation (ppk2 and exopolyphosphatase) under different incubation conditions. Sulfur-oxidizing microorganisms appeared to preferentially express genes for poly-P degradation under anoxic conditions, which may impact phosphorus cycling in a wide range of oxygen-depleted marine settings.

  7. Rapid bacterial degradation of polysaccharides in anoxic marine systems

    SciTech Connect

    Arnosti, C.; Repeta, D.J.; Blough, N.V. )

    1994-06-01

    Extracellular hydrolysis of organic macromolecules is often assumed to be the slow step in remineralization of organic matter. The authors tested this assumption by comparing the degradation of four polysaccharides (pullulan, laminarin, and two polysaccharides isolated from the marine cyanobacterium Synechococcus WH7335) to determine whether size, linkage position, or anomeric linkage affected rates or mechanisms of carbohydrate degradation by mixed cultures of anaerobic bacteria enriched from marine sediments. Gel permeation chromatography and nuclear magnetic resonance spectroscopy (NMR) were used to follow the extracellular conversion of high molecular weight polysaccharides to lower molecular weight polysaccharides and oligosaccharides which were subsequently remineralized. In all cases, substrate degradation was rapid. NMR spectra showed that preferential hydrolysis occurred at specific chemical linkages, and extracellular enzymatic hydrolysis of polysaccharides occurred far more rapidly than bacterial uptake and remineralization of the lower molecular weight oligosaccharides produced through enzymatic hydrolysis. Substrate size was not a significant determinant of remineralization rate: High molecular weight does not always correlate with slow degradation rate. The hypothesis that extracellular enzymatic hydrolysis is a slow step in the degradation of macromolecular organic matter in marine systems needs to be critically re-examined.

  8. Sediment impacts on marine sponges.

    PubMed

    Bell, James J; McGrath, Emily; Biggerstaff, Andrew; Bates, Tracey; Bennett, Holly; Marlow, Joseph; Shaffer, Megan

    2015-05-15

    Changes in sediment input to marine systems can influence benthic environments in many ways. Sponges are important components of benthic ecosystems world-wide and as sessile suspension feeders are likely to be impacted by changes in sediment levels. Despite this, little is known about how sponges respond to changes in settled and suspended sediment. Here we review the known impacts of sedimentation on sponges and their adaptive capabilities, whilst highlighting gaps in our understanding of sediment impacts on sponges. Although the literature clearly shows that sponges are influenced by sediment in a variety of ways, most studies confer that sponges are able to tolerate, and in some cases thrive, in sedimented environments. Critical gaps exist in our understanding of the physiological responses of sponges to sediment, adaptive mechanisms, tolerance limits, and the particularly the effect of sediment on early life history stages.

  9. Aquatic plant debris improve phosphorus sorption into sediment under anoxic condition.

    PubMed

    Jin, Chong-Wei; Du, Shao-Ting; Dong, Wu-Yuan; Wang, Jue-Hua; Shen, Cheng; Zhang, Yong-Song

    2013-11-01

    The effects of plant debris on phosphorus sorption by anoxic sediment were investigated. Addition of plant debris significantly enhanced the decrease of soluble relative phosphorus (SRP) in overlying water at both 10 and 30 °C during the 30-day investigation. Both cellulose and glucose, two typical plant components, also clearly enhanced the SRP decrease in anoxic overlying water. The measurement of phosphorus (P) fractions in sediment revealed that the levels of unstable P forms were decreased by plant debris addition, whereas the opposites were true for stable P forms. However, under sterilized condition, plant debris/glucose addition has no effect on the SRP decrease in overlying water. Overall, our results suggested that plant debris improve P sorption into sediment under anoxic condition through a microorganism-mediated mechanism. PMID:23686758

  10. Attenuation and colloidal mobilization of bacteriophages in natural sediments under anoxic as compared to oxic conditions.

    PubMed

    Klitzke, Sondra; Schroeder, Jendrik; Selinka, Hans-Christoph; Szewzyk, Regine; Chorus, Ingrid

    2015-06-15

    Redox conditions are known to affect the fate of viruses in porous media. Several studies report the relevance of colloid-facilitated virus transport in the subsurface, but detailed studies on the effect of anoxic conditions on virus retention in natural sediments are still missing. Therefore, we investigated the fate of viruses in natural flood plain sediments with different sesquioxide contents under anoxic conditions by considering sorption to the solid phase, sorption to mobilized colloids, and inactivation in the aqueous phase. Batch experiments were conducted under oxic and anoxic conditions at pH values between 5.1 and 7.6, using bacteriophages MS2 and PhiX174 as model viruses. In addition to free and colloid-associated bacteriophages, dissolved and colloidal concentrations of Fe, Al and organic C as well as dissolved Ca were determined. Results showed that regardless of redox conditions, bacteriophages did not adsorb to mobilized colloids, even under favourable charge conditions. Under anoxic conditions, attenuation of bacteriophages was dominated by sorption over inactivation, with MS2 showing a higher degree of sorption than PhiX174. Inactivation in water was low under anoxic conditions for both bacteriophages with about one log10 decrease in concentration during 16 h. Increased Fe/Al concentrations and a low organic carbon content of the sediment led to enhanced bacteriophage removal under anoxic conditions. However, even in the presence of sufficient Fe/A-(hydr)oxides on the solid phase, bacteriophage sorption was low. We presume that organic matter may limit the potential retention of sesquioxides in anoxic sediments and should thus be considered for the risk assessment of virus breakthrough in the subsurface.

  11. Carbon dioxide production in surface sediments of temporarily anoxic basins (Baltic Sea) and resulting sediment-water interface fluxes

    NASA Astrophysics Data System (ADS)

    Böttcher, M. E.; Al-Raei, A. M.; Winde, V.; Lenz, C.; Dellwig, O.; Leipe, T.; Segl, M.; Struck, U.

    2009-04-01

    Organic matter is mineralized in marine sediments by microbial activity using predominantly oxygen, sulfate, and metal oxides as electron acceptors. Modern euxinic basins as found in the Baltic Sea or the Black Sea are of particular importance because they may serve as type systems for anoxia in Earth's history. We present here results from biogeochemical investigations carried out in the Baltic deeps (Gotland Basin, Landsort Deep) during the first scientific cruise of RV M.S. MERIAN in 2006, additionally during RV Prof. Penck cruises in 2006 and 2007. Short sediment cores were obtained with a multi-corer and analyzed for particulate and dissolved main, minor and trace elements, pH, DIC, methane alkalinity, besides the stable carbon isotopes of dissolved inorganic carbon (DIC). Microsensors were applied to analyze steep gradients of oxygen, sulphide and sulphate. Pore water profiles are evaluated in terms of process rates and associated element fluxes using the PROFILE software (Berg et al., 1998, L&O). Gross and net anaerobic mineralization rates were additionally obtained from core incubations with 35S. Steep gradients in DIC are associated with a strong enrichment of the light stable isotope resulting in the Gotland basin from oxidized OM. Element fluxes across the sediment-water interface are compared with literature data and show for the Baltic Sea a dependence from bottom water redox conditions, and sediment compositions and formation conditions (e.g., accumulation rates). DIC in the anoxic part of the water column in the Landsort Deep and the Gotland Deep show relatively similar isotope values, close to the bottom water value, but steep gradients towards heavier values above the pelagic redoxcline. Acknowledgements: The research was supported by Leibniz IO Warnemünde, DFG (Cruise RV MSM MERIAN 01), and MPG. Thanks to B. Schneider and F. Pollehne stimulating discussions, and S. Lage and A. Schipper for technical support.

  12. The challenge of proving the existence of metazoan life in permanently anoxic deep-sea sediments.

    PubMed

    Danovaro, Roberto; Gambi, Cristina; Dell'Anno, Antonio; Corinaldesi, Cinzia; Pusceddu, Antonio; Neves, Ricardo Cardoso; Kristensen, Reinhardt Møbjerg

    2016-01-01

    The demonstration of the existence of metazoan life in absence of free oxygen is one of the most fascinating and difficult challenges in biology. Danovaro et al. (2010) discovered three new species of the Phylum Loricifera, living in the anoxic sediments of the L'Atalante, a deep-hypersaline anoxic basin of the Mediterranean Sea. Multiple and independent analyses based on staining, incorporation of radiolabeled substrates, CellTracker Green incorporation experiments and ultra-structure analyses, allowed Danovaro et al. (2010) to conclude that these animals were able to spend their entire life cycle under anoxic conditions. Bernhard et al. (2015) investigated the same basin. Due to technical difficulties in sampling operations, they could not collect samples from the permanently anoxic sediment, and sampled only the redoxcline portion of the L'Atalante basin. They found ten individuals of Loricifera and provided alternative interpretations of the results of Danovaro et al. (2010). Here we analyze these interpretations, and present additional evidence indicating that the Loricifera encountered in the anoxic basin L'Atalante were actually alive at the time of sampling. We also discuss the reliability of different methodologies and approaches in providing evidence of metazoans living in anoxic conditions, paving the way for future investigations.This paper is a response to Bernhard JM, Morrison CR, Pape E, Beaudoin DJ, Todaro MA, Pachiadaki MG, Kormas KAr, Edgcomb VG. 2015. Metazoans of redoxcline sediments in Mediterranean deep-sea hypersaline anoxic basins. BMC Biology 2015 13:105.See research article at http://bmcbiol.biomedcentral.com/articles/10.1186/s12915-015-0213-6. PMID:27267928

  13. A thiosulfate shunt in the sulfur cycle of marine sediments.

    PubMed

    Jørgensen, B B

    1990-07-13

    The oxidation of sulfide, generated by bacterial sulfate reduction, is a key process in the biogeochemistry of marine sediments, yet the pathways and oxidants are poorly known. By the use of (35)S-tracer studies of the S cycle in marine and freshwater sediments, a novel shunt function of thiosulfate (S(2)O(3)(2-)) was identified. The S(2)O(3)(2-) constituted 68 to 78 percent of the immediate HS(-)-oxidation products and was concurrently (i) reduced back to HS(-), (ii) oxidized to SO(4)(2-), and (iii) disproportionated to HS(-) + SO(4)(2-). The small thiosulfate pool is thus involved in a dynamic HS(-) - S(2)O(3)(2-) cycle in anoxic sediments. The disproportionation of thiosulfate may help account for the large difference in isotopic composition ((34)S/(32)S) of sulfate and sulfides in sediments and sedimentary rocks.

  14. Formation of Dimethyl Sulfide and Methanethiol in Anoxic Freshwater Sediments

    PubMed Central

    Lomans, B. P.; Smolders, A.; Intven, L. M.; Pol, A.; Op, De; Van Der Drift, C.

    1997-01-01

    Concentrations of volatile organic sulfur compounds (VOSC) were measured in water and sediment columns of ditches in a minerotrophic peatland in The Netherlands. VOSC, with methanethiol (4 to 40 nM) as the major compound, appeared to be mainly of sediment origin. Both VOSC and hydrogen sulfide concentrations decreased dramatically towards the water surface. High methanethiol and high dimethyl sulfide concentrations in the sediment and just above the sediment surface coincided with high concentrations of hydrogen sulfide (correlation factors, r = 0.91 and r = 0.81, respectively). Production and degradation of VOSC were studied in 32 sediment slurries collected from various freshwater systems in The Netherlands. Maximal endogenous methanethiol production rates of the sediments tested (up to 1.44 (mu)mol per liter of sediment slurry (middot) day(sup-1)) were determined after inhibition of methanogenic and sulfate-reducing populations in order to stop VOSC degradation. These experiments showed that the production and degradation of VOSC in sediments are well balanced. Statistical analysis revealed multiple relationships of methanethiol production rates with the combination of methane production rates (indicative of total anaerobic mineralization) and hydrogen sulfide concentrations (r = 0.90) or with the combination of methane production rates and the sulfate/iron ratios in the sediment (r = 0.82). These findings and the observed stimulation of methanethiol formation in sediment slurry incubations in which the hydrogen sulfide concentrations were artificially increased provided strong evidence that the anaerobic methylation of hydrogen sulfide is the main mechanism for VOSC formation in most freshwater systems. Methoxylated aromatic compounds are likely a major source of methyl groups for this methylation of hydrogen sulfide, since they are important degradation products of the abundant biopolymer lignin. Increased sulfate concentrations in several freshwater

  15. Enhancing the intrinsic bioremediation of PAH-contaminated anoxic estuarine sediments with biostimulating agents.

    PubMed

    Bach, Quang-Dung; Kim, Sang-Jin; Choi, Sung-Chan; Oh, Young-Sook

    2005-08-01

    Estuarine sediments are frequently polluted with hydrocarbons from fuel spills and industrial wastes. Polycyclic aromatic hydrocarbons (PAHs) are components of these contaminants that tend to accumulate in the sediment due to their low aqueous solubility, low volatility, and high affinity for particulate matter. The toxic, recalcitrant, mutagenic, and carcinogenic nature of these compounds may require aggressive treatment to remediate polluted sites effectively. In petroleum-contaminated sediments near a petrochemical industry in Gwangyang Bay, Korea, in situ PAH concentrations ranged from 10 to 2,900 microg/kg dry sediment. To enhance the biodegradation rate of PAHs under anaerobic conditions, sediment samples were amended with biostimulating agents alone or in combination: nitrogen and phosphorus in the form of slow-release fertilizer (SRF), lactate, yeast extract (YE), and Tween 80. When added to the sediment individually, all tested agents enhanced the degradation of PAHs, including naphthalene, acenaphthene, anthracene, fluorene, phenanthrene, fluoranthene, pyrene, chrysene, and benzo[a]pyrene. Moreover, the combination of SRF, Tween 80, and lactate increased the PAH degradation rate 1.2-8.2 times above that of untreated sediment (0.01-10 microg PAH/kg dry sediment/day). Our results indicated that in situ contaminant PAHs in anoxic sediment, including high molecular weight PAHs, were degraded biologically and that the addition of stimulators increased the biodegradation potential of the intrinsic microbial populations. Our results will contribute to the development of new strategies for in situ treatment of PAH-contaminated anoxic sediments.

  16. Centimeter-long electron transport in marine sediments via conductive minerals.

    PubMed

    Malvankar, Nikhil S; King, Gary M; Lovley, Derek R

    2015-02-01

    Centimeter-long electron conduction through marine sediments, in which electrons derived from sulfide in anoxic sediments are transported to oxygen in surficial sediments, may have an important influence on sediment geochemistry. Filamentous bacteria have been proposed to mediate the electron transport, but the filament conductivity could not be verified and other mechanisms are possible. Surprisingly, previous investigations have never actually measured the sediment conductivity or its basic physical properties. Here we report direct measurements that demonstrate centimeter-long electron flow through marine sediments, with conductivities sufficient to account for previously estimated electron fluxes. Conductivity was lost for oxidized sediments, which contrasts with the previously described increase in the conductivity of microbial biofilms upon oxidation. Adding pyrite to the sediments significantly enhanced the conductivity. These results suggest that the role of conductive minerals, which are more commonly found in sediments than centimeter-long microbial filaments, need to be considered when modeling marine sediment biogeochemistry.

  17. The lipid geochemistry of interstitial waters of recent marine sediments

    SciTech Connect

    Saliot, A.; Brault, M.; Boussuge, C. )

    1988-04-01

    To elucidate the nature of biogeochemical processes occurring at the water-sediment interface, the authors have analyzed fatty acids, n-alkanes and sterols contained in interstitial waters collected from oxic and anoxic marine sediments in the eastern and western intertropical Atlantic Ocean and in the Arabian Sea. Lipid concentrations in interstitial waters vary widely and are generally much higher than concentrations encountered in the overlying sea water. Higher concentrations in interstitial water are observed in environments favorable for organic input and preservation of the organic matter in the water column and in the surficial sediment. The analysis of biogeochemical markers in the various media of occurrence of the organic matter such as sea water, suspended particles, settling particles and sediment is discussed in terms of differences existing between these media and bio-transformations of the organic matter at the water-sediment interface.

  18. Degradation of trifluoroacetate in oxic and anoxic sediments

    USGS Publications Warehouse

    Visscher, P.T.; Culbertson, C.W.; Oremland, R.S.

    1994-01-01

    THE deleterious effect of chlorofluorocarbons on stratospheric ozone has led to international cooperation to end their use. The search for acceptable alternatives has focused on hydrofluorocarbons (HFCs) or hydrochlorofluorocarbons (HCFCs) which are attractive because they have relatively short atmospheric residence times. HFCs and HCFCs are attacked by tropospheric hydroxyl radicals, leading to the formation of trifluoroacetate (TFA). Most of the atmospheric TFA is deposited at the Earth's surface, where it is thought to be highly resistant to bacterial attack. Therefore, use of HCFCs and HFCs may lead to accumulation of TFA in soils, where it could prove toxic or inhibitory to plants and soil microbial communities. Although little is known about the toxicity of TFA, monofluoroacetate, which occurs at low levels in some plants and which is susceptible to slow attack by aerobic soil microbes, is known to be acutely toxic. Here we report that TFA can be rapidly degraded microbially under anoxic and oxic conditions. These results imply that significant microbial sinks exist in nature for the elimination of TFA from the environment. We also show that oxic degradation of TFA leads to the formation of fluoroform, a potential ozone-depleting compound with a much longer atmospheric lifetime than the parent compounds.The deleterious effect of chlorofluorcarbons on stratospheric ozone has led to international cooperation to end their use. The search for acceptable alternatives has focused on hydroflnorocarbons (HFCs) or hydrochloroflnorcarbons (HCFs) which are attractive because they have relatively short atmospheric residence times. HFCs and HCFs are attacked by tropospheric hydroxyl radicals, leading to the formation of trifluoroacetate (TFA). Most of the atmospheric TFA is deposited at the Earth's surface, where it is thought to be highly resistant to bacterial attack. Therefore, use of HCFs and HCFs may lead to accummulation of TFA in soils, where it could prove toxic

  19. 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.

  20. Microbial formation of ethane in anoxic estuarine sediments

    USGS Publications Warehouse

    Oremland, Ronald S.

    1981-01-01

    Estuarine sediment slurries produced methane and traces of ethane when incubated under hydrogen. Formation of methane occurred over a broad temperature range with an optimum above 65°C. Ethane formation had a temperature optimum at 40°C. Formation of these two gases was inhibited by air, autoclaving, incubation at 4 and 80°C, and by the methanogenic inhibitor, 2-bromoethanesulfonic acid. Ethane production was stimulated by addition of ethylthioethanesulfonic acid, and production from ethylthioethanesulfonic acid was blocked by 2-bromoethanesulfonic acid. A highly purified enrichment culture of a methanogenic bacterium obtained from sediments produced traces of ethane from ethylthioethanesulfonic acid. These results indicate that the small quantities of ethane found in anaerobic sediments can be formed by certain methanogenic bacteria.

  1. ENAA studies of pollution in anoxic Black Sea sediments.

    PubMed

    Duliu, Octavian G; Cristache, Carmen; Oaie, Gheorghe; Culicov, Otilia A; Frontasyeva, Marina V; Toma, Magdalena

    2009-06-01

    The vertical distributions of five potential pollutants - Zn, As, Br, Sn, and Sb - were determined via epithermal neutron activation in the upper 50cm of unconsolidated sediments from the Black Sea, which were collected 600m below sea surface. This analysis demonstrated increasing concentrations towards the upper limits of sediments, which were greater than alert concentrations in the case of As and Br, and in accordance with Romanian Environment Regulations. The utilization of Chernobyl (137)Cs as a time marker allowed for dating of this region to the last 100 years. PMID:19261305

  2. Glacial marine sedimentation: Paleoclimatic significance

    SciTech Connect

    Anderson, J.B.; Ashley, G.M.

    1991-01-01

    This publication resulted from a symposium held during the 1988 Annual Meeting of the Geological Society of America. Many, but not all, contributors to the symposium have papers in this volume. This Special Paper consists of 14 chapters and a Subject/Geographic index. Each chapter has is own list of references. The papers cover a wide range of modem climate/ ocean environments, including papers on glacial marine sediments from Antarctica, the fiords of Alaska, and sediments from the Canadian High Arctic. In addition, three papers discuss [open quote]old[close quotes] glacial marine records (i.e., pre-Tertiary), and one paper discusses the Yakataga Formation of the Gulf of Alaska which is a Miocene-to-late-Pleistocene sequence. The last chapter in the book includes a survey and summary of the evidence for the paleoclimatic significance of glacial marine sediments by the two editors, John Anderson and Gail Ashley. It is worth noting that Anderson and Domack state in the Foreword that there is a considerable variation in terminology; hence they employ a series of definitions which they urge the other authors to employ. They define and explain what they mean by [open quotes]polar ice cap,[close quotes] [open quote]polar tundra (subpolar),[close quotes] and [open quotes]temperate oceanic and boreal[close quotes] in terms of the dominant glacial and glacial marine processes. Although one might quarrel with the terminology, the broad differences between these three glaciological regimes are indeed fundamental and need to be sought in the geological record. The flavor of the volume can be judged by some of the chapter titles. Contributions on Antarctica include a paper by Anderson and other entitled [open quote]Sedimentary facies associated with Antarctica's floating ice masses[close quotes] and a companion paper by Anderson and Domack which deals with the extremely complex glacial marine facies (13 facies are delimited) in McMurdo Sound, Antarctica.

  3. Effects of soil erosion and anoxic-euxinic ocean in the Permian-Triassic marine crisis.

    PubMed

    Kaiho, Kunio; Saito, Ryosuke; Ito, Kosuke; Miyaji, Takashi; Biswas, Raman; Tian, Li; Sano, Hiroyoshi; Shi, Zhiqiang; Takahashi, Satoshi; Tong, Jinnan; Liang, Lei; Oba, Masahiro; Nara, Fumiko W; Tsuchiya, Noriyoshi; Chen, Zhong-Qiang

    2016-08-01

    The largest mass extinction of biota in the Earth's history occurred during the Permian-Triassic transition and included two extinctions, one each at the latest Permian (first phase) and earliest Triassic (second phase). High seawater temperature in the surface water accompanied by euxinic deep-intermediate water, intrusion of the euxinic water to the surface water, a decrease in pH, and hypercapnia have been proposed as direct causes of the marine crisis. For the first-phase extinction, we here add a causal mechanism beginning from massive soil and rock erosion and leading to algal blooms, release of toxic components, asphyxiation, and oxygen-depleted nearshore bottom water that created environmental stress for nearshore marine animals. For the second-phase extinction, we show that a soil and rock erosion/algal bloom event did not occur, but culmination of anoxia-euxinia in intermediate waters did occur, spanning the second-phase extinction. We investigated sedimentary organic molecules, and the results indicated a peak of a massive soil erosion proxy followed by peaks of marine productivity proxy. Anoxic proxies of surface sediments and water occurred in the shallow nearshore sea at the eastern and western margins of the Paleotethys at the first-phase extinction horizon, but not at the second-phase extinction horizon. Our reconstruction of ocean redox structure at low latitudes indicates that a gradual increase in temperature spanning the two extinctions could have induced a gradual change from a well-mixed oxic to a stratified euxinic ocean beginning immediately prior to the first-phase extinction, followed by culmination of anoxia in nearshore surface waters and of anoxia and euxinia in the shallow-intermediate waters at the second-phase extinction over a period of approximately one million years or more. Enhanced global warming, ocean acidification, and hypercapnia could have caused the second-phase extinction approximately 60 kyr after the first

  4. Effects of soil erosion and anoxic-euxinic ocean in the Permian-Triassic marine crisis.

    PubMed

    Kaiho, Kunio; Saito, Ryosuke; Ito, Kosuke; Miyaji, Takashi; Biswas, Raman; Tian, Li; Sano, Hiroyoshi; Shi, Zhiqiang; Takahashi, Satoshi; Tong, Jinnan; Liang, Lei; Oba, Masahiro; Nara, Fumiko W; Tsuchiya, Noriyoshi; Chen, Zhong-Qiang

    2016-08-01

    The largest mass extinction of biota in the Earth's history occurred during the Permian-Triassic transition and included two extinctions, one each at the latest Permian (first phase) and earliest Triassic (second phase). High seawater temperature in the surface water accompanied by euxinic deep-intermediate water, intrusion of the euxinic water to the surface water, a decrease in pH, and hypercapnia have been proposed as direct causes of the marine crisis. For the first-phase extinction, we here add a causal mechanism beginning from massive soil and rock erosion and leading to algal blooms, release of toxic components, asphyxiation, and oxygen-depleted nearshore bottom water that created environmental stress for nearshore marine animals. For the second-phase extinction, we show that a soil and rock erosion/algal bloom event did not occur, but culmination of anoxia-euxinia in intermediate waters did occur, spanning the second-phase extinction. We investigated sedimentary organic molecules, and the results indicated a peak of a massive soil erosion proxy followed by peaks of marine productivity proxy. Anoxic proxies of surface sediments and water occurred in the shallow nearshore sea at the eastern and western margins of the Paleotethys at the first-phase extinction horizon, but not at the second-phase extinction horizon. Our reconstruction of ocean redox structure at low latitudes indicates that a gradual increase in temperature spanning the two extinctions could have induced a gradual change from a well-mixed oxic to a stratified euxinic ocean beginning immediately prior to the first-phase extinction, followed by culmination of anoxia in nearshore surface waters and of anoxia and euxinia in the shallow-intermediate waters at the second-phase extinction over a period of approximately one million years or more. Enhanced global warming, ocean acidification, and hypercapnia could have caused the second-phase extinction approximately 60 kyr after the first

  5. Anoxic carbon degradation in Arctic sediments: Microbial transformations of complex substrates

    NASA Astrophysics Data System (ADS)

    Arnosti, C.; Finke, N.; Larsen, O.; Ghobrial, S.

    2005-05-01

    Complex substrates are degraded in anoxic sediments by the concerted activities of diverse microbial communities. To explore the effects of substrate complexity on carbon transformations in permanently cold anoxic sediments, four substrates— Spirulina cells, Isochrysis cells, and soluble high molecular weight carbohydrate-rich extracts of these cells (Spir-Ex and Iso-Ex)—were added to sediments collected from Svalbard. The sediments were homogenized, incubated anaerobically in gas-tight bags at 0°C, and enzyme activities, fermentation, and terminal respiration were monitored over a 1134 h time course. All substrate additions yielded a fraction (8%-13%) of carbon that was metabolized to CO 2 over the first 384 h of incubation. The timecourse of VFA (volatile fatty acid) production and consumption, as well as the suite of VFAs produced, was similar for all substrates. After this phase, pathways of carbon degradation diverged, with an additional 43%, 32%, 33%, and 8% of Isochrysis, Iso-Ex, Spirulina, and Spir-Ex carbon respired to CO 2 over the next 750 h of incubation. Somewhat surprisingly, the soluble, carbohydrate-rich extracts did not prove to be more labile substrates than the whole cells from which they were derived. Although Spirulina and Iso-Ex differed in physical and chemical characteristics (solid/soluble, C/N ratio, lipid and carbohydrate content), nearly identical quantities of carbon were respired to CO 2. In contrast, only 15% of Spir-Ex carbon was respired, despite the initial burst of activity that it fueled, its soluble nature, and its relatively high (50%) carbohydrate content. The microbial community in these cold anoxic sediments clearly has the capacity to react rapidly to carbon input; extent and timecourse of remineralization of added carbon is similar to observations made at much higher temperatures in temperate sediments. The extent of carbon remineralization from these specific substrates, however, would not likely have been predicted

  6. Redox processes in pore water of anoxic sediments with shallow gas.

    PubMed

    Ramírez-Pérez, A M; de Blas, E; García-Gil, S

    2015-12-15

    The Ría de Vigo (NW Spain) has a high organic matter content and high rates of sedimentation. The microbial degradation of this organic matter has led to shallow gas accumulations of methane, currently distributed all along the ría. These peculiar characteristics favor the development of anoxic conditions that can determine the dynamics of iron and manganese. In order to study the role played by iron and manganese in the processes that take place in anoxic sediments with shallow gas, four gravity cores were retrieved in anoxic sediments of the Ría de Vigo in November 2012. Methane was present in two of them, below 90cm in the inner zone and below 200cm, in the outer zone. Pore water was collected and analyzed for vertical profiles of pH, sulfide, sulfate, iron and manganese concentrations. Sulfate concentrations decreased with depth but never reached the minimum detection limit. High sulfide concentrations were measured in all cores. The highest sulfide concentrations were found in the inner zone with methane and the lowest were in the outer zone without methane. Concentrations of iron and manganese reached maximum values in the upper layers of the sediment, decreasing with depth, except in the outer zone without gas, where iron and manganese concentration increased strongly toward the bottom of the sediment. In areas with shallow gas iron reduction, sulfate reduction and methane production processes coexist, showing that the traditional redox cascade is highly simplified and suggesting that iron may be involved in a cryptic sulfur cycle and in the oxidation of methane. PMID:26312406

  7. High bacterial biodiversity increases degradation performance of hydrocarbons during bioremediation of contaminated harbor marine sediments.

    PubMed

    Dell'Anno, Antonio; Beolchini, Francesca; Rocchetti, Laura; Luna, Gian Marco; Danovaro, Roberto

    2012-08-01

    We investigated changes of bacterial abundance and biodiversity during bioremediation experiments carried out on oxic and anoxic marine harbor sediments contaminated with hydrocarbons. Oxic sediments, supplied with inorganic nutrients, were incubated in aerobic conditions at 20 °C and 35 °C for 30 days, whereas anoxic sediments, amended with organic substrates, were incubated in anaerobic conditions at the same temperatures for 60 days. Results reported here indicate that temperature exerted the main effect on bacterial abundance, diversity and assemblage composition. At higher temperature bacterial diversity and evenness increased significantly in aerobic conditions, whilst decreased in anaerobic conditions. In both aerobic and anaerobic conditions, biodegradation efficiencies of hydrocarbons were significantly and positively related with bacterial richness and evenness. Overall results presented here suggest that bioremediation strategies, which can sustain high levels of bacterial diversity rather than the selection of specific taxa, may significantly increase the efficiency of hydrocarbon degradation in contaminated marine sediments.

  8. Archaeal and bacterial communities respond differently to environmental gradients in anoxic sediments of a California hypersaline lake, the Salton Sea.

    PubMed

    Swan, Brandon K; Ehrhardt, Christopher J; Reifel, Kristen M; Moreno, Lilliana I; Valentine, David L

    2010-02-01

    Sulfidic, anoxic sediments of the moderately hypersaline Salton Sea contain gradients in salinity and carbon that potentially structure the sedimentary microbial community. We investigated the abundance, community structure, and diversity of Bacteria and Archaea along these gradients to further distinguish the ecologies of these domains outside their established physiological range. Quantitative PCR was used to enumerate 16S rRNA gene abundances of Bacteria, Archaea, and Crenarchaeota. Community structure and diversity were evaluated by terminal restriction fragment length polymorphism (T-RFLP), quantitative analysis of gene (16S rRNA) frequencies of dominant microorganisms, and cloning and sequencing of 16S rRNA. Archaea were numerically dominant at all depths and exhibited a lesser response to environmental gradients than that of Bacteria. The relative abundance of Crenarchaeota was low (0.4 to 22%) at all depths but increased with decreased carbon content and increased salinity. Salinity structured the bacterial community but exerted no significant control on archaeal community structure, which was weakly correlated with total carbon. Partial sequencing of archaeal 16S rRNA genes retrieved from three sediment depths revealed diverse communities of Euryarchaeota and Crenarchaeota, many of which were affiliated with groups previously described from marine sediments. The abundance of these groups across all depths suggests that many putative marine archaeal groups can tolerate elevated salinity (5.0 to 11.8% [wt/vol]) and persist under the anaerobic conditions present in Salton Sea sediments. The differential response of archaeal and bacterial communities to salinity and carbon patterns is consistent with the hypothesis that adaptations to energy stress and availability distinguish the ecologies of these domains. PMID:19948847

  9. Detailed Phosphorus Geochemistry of Sediments from the Equatorial Proto-Atlantic at Demerara Rise During Oceanic Anoxic Event 2

    NASA Astrophysics Data System (ADS)

    Smith, M. E.; Latimer, J.; Pugh, E.

    2011-12-01

    Oceanic anoxic events (OAE) are associated with increased organic matter burial and possibly major changes in marine nutrient cycling. Phosphorus (P) limits biological productivity on geologic timescales, thus detailed P geochemistry may provide insight into the role of nutrients on the formation of these organic-rich deposits. P geochemical records that encompass the complete OAE 2 interval across the Cenomanian-Turonian boundary (CTB, ~94 Ma) are rare, and detailed P geochemical records are usually limited to relatively shallow settings. In this study, a sequential extraction (SEDEX) technique is employed to evaluate the sedimentary distribution of P (oxide-associated, authigenic, detrital and organic) in sediments mainly consisting of laminated black shales spanning the CTB/OAE2 interval at a sample resolution of ~2-5 cm collected from Demerara Rise during ODP Leg 207. Intermediate (Site 1260, 2549 m) and deep-sea (Site 1258, 3292 m) water depths will be compared to assess variations in P distribution across the CTB, with paleo-water depths of ~500 to 1000 m respectively. Diagenetic and redox conditions result in alterations of the sedimentary distribution of P in ancient sediments; most notably the effect of "sink-switching" of organic P to authigenic and/or oxide-associated phases. Here we evaluate the impacts of diagenetic remobilization of P through the critical OAE 2 interval. Sequential extraction enables an examination of the dominant pathways of P removal from the ocean thus providing insight into marine P mass balance. Initial results reveal little or undetectable concentrations of oxide-associated and organic P. Authigenic and detrital phases dominate the extractable P. Under anoxic conditions Fe-oxides would no longer be a major sedimentary sink and would likely lead to losses of oxide-associated P from the sediments. Low concentrations of organic P are likely due to diagenetic alteration to authigenic carbonate fluorapatite (CFA) and oxide

  10. Microbial conversion of inorganic carbon to dimethyl sulfide in anoxic lake sediment (Plußsee, Germany)

    NASA Astrophysics Data System (ADS)

    Lin, Y. S.; Heuer, V. B.; Ferdelman, T. G.; Hinrichs, K.-U.

    2010-08-01

    -forming pathway may be relevant for anoxic environments such as hydrothermally influenced sediments and fluids and sulfate-methane transition zones in marine sediments.

  11. Degradation of selected halogenated ethanes in anoxic sediment-water systems

    SciTech Connect

    Jafvert, C.T.; Wolfe, N.L.

    1987-01-01

    The degradation of selected halogenated ethanes was studied in anoxic sediment-water suspensions at 1 to 20% sediment concentrations. Batch kinetic experiments were used to quantify decay. Eh measurements of all suspensions were below -100mV (vs SHE), indicating reduced environmental conditions. Hexachloroethane (HCA), 1,1,2,2-tetrachloroethane (TTCA), 1,2-diiodoethane (DIA) and 1,2-dibromoethane (DBA) were degraded within minutes to days, but 1,2-dichloroethane (DCA) remained in the system through 35 d, at which point the study was ended. The major route of transformation of these compounds in the system was vicinal dehalogenation. Rates of disappearance followed pseudo-first-order kinetics at low reactant concentrations and high sediment concentration.

  12. Genomic potential for nitrogen assimilation in uncultivated members of Prochlorococcus from an anoxic marine zone.

    PubMed

    Astorga-Eló, Marcia; Ramírez-Flandes, Salvador; DeLong, Edward F; Ulloa, Osvaldo

    2015-05-01

    Cyanobacteria of the genus Prochlorococcus are the most abundant photosynthetic marine organisms and key factors in the global carbon cycle. The understanding of their distribution and ecological importance in oligotrophic tropical and subtropical waters, and their differentiation into distinct ecotypes, is based on genetic and physiological information from several isolates. Currently, all available Prochlorococcus genomes show their incapacity for nitrate utilization. However, environmental sequence data suggest that some uncultivated lineages may have acquired this capacity. Here we report that uncultivated low-light-adapted Prochlorococcus from the nutrient-rich, low-light, anoxic marine zone (AMZ) of the eastern tropical South Pacific have the genetic potential for nitrate uptake and assimilation. All genes involved in this trait were found syntenic with those present in marine Synechococcus. Genomic and phylogenetic analyses also suggest that these genes have not been aquired recently, but perhaps were retained from a common ancestor, highlighting the basal characteristics of the AMZ lineages within Prochlorococcus.

  13. Genomic potential for nitrogen assimilation in uncultivated members of Prochlorococcus from an anoxic marine zone

    PubMed Central

    Astorga-Eló, Marcia; Ramírez-Flandes, Salvador; DeLong, Edward F; Ulloa, Osvaldo

    2015-01-01

    Cyanobacteria of the genus Prochlorococcus are the most abundant photosynthetic marine organisms and key factors in the global carbon cycle. The understanding of their distribution and ecological importance in oligotrophic tropical and subtropical waters, and their differentiation into distinct ecotypes, is based on genetic and physiological information from several isolates. Currently, all available Prochlorococcus genomes show their incapacity for nitrate utilization. However, environmental sequence data suggest that some uncultivated lineages may have acquired this capacity. Here we report that uncultivated low-light-adapted Prochlorococcus from the nutrient-rich, low-light, anoxic marine zone (AMZ) of the eastern tropical South Pacific have the genetic potential for nitrate uptake and assimilation. All genes involved in this trait were found syntenic with those present in marine Synechococcus. Genomic and phylogenetic analyses also suggest that these genes have not been aquired recently, but perhaps were retained from a common ancestor, highlighting the basal characteristics of the AMZ lineages within Prochlorococcus. PMID:25700337

  14. Genomic potential for nitrogen assimilation in uncultivated members of Prochlorococcus from an anoxic marine zone.

    PubMed

    Astorga-Eló, Marcia; Ramírez-Flandes, Salvador; DeLong, Edward F; Ulloa, Osvaldo

    2015-05-01

    Cyanobacteria of the genus Prochlorococcus are the most abundant photosynthetic marine organisms and key factors in the global carbon cycle. The understanding of their distribution and ecological importance in oligotrophic tropical and subtropical waters, and their differentiation into distinct ecotypes, is based on genetic and physiological information from several isolates. Currently, all available Prochlorococcus genomes show their incapacity for nitrate utilization. However, environmental sequence data suggest that some uncultivated lineages may have acquired this capacity. Here we report that uncultivated low-light-adapted Prochlorococcus from the nutrient-rich, low-light, anoxic marine zone (AMZ) of the eastern tropical South Pacific have the genetic potential for nitrate uptake and assimilation. All genes involved in this trait were found syntenic with those present in marine Synechococcus. Genomic and phylogenetic analyses also suggest that these genes have not been aquired recently, but perhaps were retained from a common ancestor, highlighting the basal characteristics of the AMZ lineages within Prochlorococcus. PMID:25700337

  15. Metal impacts on microbial biomass in the anoxic sediments of a contaminated lake

    SciTech Connect

    Gough, Heidi L.; Dahl, Amy L.; Nolan, Melissa A.; Gaillard, Jean-Francois; Stahl, David A.

    2008-04-26

    Little is known about the long-term impacts of metal contamination on the microbiota of anoxic lake sediments. In this study, we examined microbial biomass and metals (arsenic, cadmium, chromium, copper, iron, lead, manganese, and zinc) in the sediments of Lake DePue, a backwater lake located near a former zinc smelter. Sediment core samples were examined using two independent measures for microbial biomass (total microscopic counts and total phospholipid-phosphate concentrations), and for various fractions of each metal (pore water extracts, sequential extractions, and total extracts of all studied metals and zinc speciation by X-ray absorption fine structure (XAFS). Zinc concentrations were up to 1000 times higher than reported for sediments in the adjacent Illinois River, and ranged from 21,400 mg/kg near the source to 1,680 mg/kg near the river. However, solid metal fractions were not well correlated with pore water concentrations, and were not good predictors of biomass concentrations. Instead, biomass, which varied among sites by as much as two-times, was inversely correlated with concentrations of pore water zinc and arsenic as established by multiple linear regression. Monitoring of other parameters known to naturally influence biomass in sediments (e.g., organic carbon concentrations, nitrogen concentrations, pH, sediment texture, and macrophytes) revealed no differences that could explain observed biomass trends. This study provides strong support for control of microbial abundance by pore water metal concentrations in contaminated freshwater sediments.

  16. Impact of LIP formation on marine productivity during early Aptian and latest Cenomanian Oceanic Anoxic Events

    NASA Astrophysics Data System (ADS)

    Erba, E.; Duncan, R.

    2003-04-01

    Of all the Cretaceous Oceanic Anoxic Events (OAEs), the Early Aptian OAE1a and latest Cenomanian OAE2 are truly global in nature and typically represented by carbonate crisis and Corg-rich black shales. They correlate with onset and climax of the mid-Cretaceous greenhouse, a time of exceptional warmth with accelerated burial of organic matter, carbon and strontium isotope excursions, and major biotic changes. Extraordinary rates of volcanism during the formation of Ontong Java and Caribbean Plateaus are proposed to have introduced excess CO_2 in the ocean/atmosphere system, turning the climate into a super-greenhouse state. High-resolution multidisciplinary investigations of well-dated sections indicate that marine ecosystems reacted to higher fertility and pCO2 by reducing biomineralization and increasing production of organic matter. In particular, rates of calcitization and evolutionary changes of micrite-forming calcareous nannoplankton (the biological and carbonate pump) affected the organic and inorganic carbon cycle as well as diffusion of atmospheric CO_2 in the Cretaceous ocean. Increasing geological evidence suggests that OAE1a and OAE2 were mainly oceanic productivity events, directly or indirectly controlled by submarine volcanic eruptions. High levels of volcanogenic CO_2 in the atmosphere accelerated continental weathering and increased nutrient content in oceanic surface waters via river run-off. However, only coastal eutrophication can be triggered by river input, and this mechanism cannot explain enhanced primary productivity in remote parts of large oceans like those recorded in wide-spread sediments of OAE1a and OAE2. Conversely, global productivity can be stimulated by hydrothermal megaplumes that introduce in the oceans high concentrations of dissolved and particulate metals that are biolimiting (and toxic) and, consequently, can trigger large blooms (and deaths) of primary producers. We speculate that during OAE1a and OAE2, higher productivity

  17. Bacterial dissimilatory reduction of arsenic(V) to arsenic(III) in anoxic sediments

    USGS Publications Warehouse

    Dowdle, P.R.; Laverman, A.M.; Oremland, R.S.

    1996-01-01

    Incubation of anoxic salt marsh sediment slurries with 10 mM As(V) resulted in the disappearance over time of the As(V) in conjunction with its recovery as As(III). No As(V) reduction to As(III) occurred in heat- sterilized or formalin-killed controls or in live sediments incubated in air. The rate of As(V) reduction in slurries was enhanced by addition of the electron donor lactate, H2, or glucose, whereas the respiratory inhibitor/uncoupler dinitrophenol, rotenone, or 2-heptyl-4-hydroxyquinoline N-oxide blocked As(V) reduction. As(V) reduction was also inhibited by tungstate but not by molybdate, sulfate, or phosphate. Nitrate inhibited As(V) reduction by its action as a preferred respiratory electron acceptor rather than as a structural analog of As(V). Nitrate-respiring sediments could reduce As(V) to As(III) once all the nitrate was removed. Chloramphenicol blocked the reduction of As(V) to As(III) in nitrate- respiring sediments, suggesting that nitrate and arsenate were reduced by separate enzyme systems. Oxidation of [2-14C]acetate to 14CO2 by salt marsh and freshwater sediments was coupled to As(V). Collectively, these results show that reduction of As(V) in sediments proceeds by a dissimilatory process. Bacterial sulfate reduction was completely inhibited by As(V) as well as by As(III).

  18. Genetic diversity of microbial eukaryotes in anoxic sediment around fumaroles on a submarine caldera floor based on the small-subunit rDNA phylogeny.

    PubMed

    Takishita, Kiyotaka; Miyake, Hiroshi; Kawato, Masaru; Maruyama, Tadashi

    2005-06-01

    Recent culture-independent molecular analyses have shown the diversity and ecological importance of microbial eukaryotes (protists) in various marine environments. In the present study we directly extracted DNA from anoxic sediment near active fumaroles on a submarine caldera floor at a depth of 200 m and constructed genetic libraries of PCR-amplified eukaryotic small-subunit (SSU) rDNA. By sequencing cloned SSU rDNA of the libraries and their phylogenetic analyses, it was shown that most sequences have affiliations with known major lineages of eukaryotes (Cercozoa, Alveolata, stramenopiles and Opisthokonta). In particular, some sequences were closely related to those of representatives of eukaryotic parasites, such as Phagomyxa and Cryothecomonas of Cercozoa, Pirsonia of stramenopiles and Ichthyosporea of Opisthokonta, although it is not clear whether the organisms occur in free-living or parasitic forms. In addition, other sequences did not seem to be related to any described eukaryotic lineages suggesting the existence of novel eukaryotes at a high-taxonomic level in the sediment. The community composition of microbial eukaryotes in the sediment we surveyed was different overall from those of other anoxic marine environments previously investigated. PMID:15744454

  19. Genetic diversity of microbial eukaryotes in anoxic sediment around fumaroles on a submarine caldera floor based on the small-subunit rDNA phylogeny.

    PubMed

    Takishita, Kiyotaka; Miyake, Hiroshi; Kawato, Masaru; Maruyama, Tadashi

    2005-06-01

    Recent culture-independent molecular analyses have shown the diversity and ecological importance of microbial eukaryotes (protists) in various marine environments. In the present study we directly extracted DNA from anoxic sediment near active fumaroles on a submarine caldera floor at a depth of 200 m and constructed genetic libraries of PCR-amplified eukaryotic small-subunit (SSU) rDNA. By sequencing cloned SSU rDNA of the libraries and their phylogenetic analyses, it was shown that most sequences have affiliations with known major lineages of eukaryotes (Cercozoa, Alveolata, stramenopiles and Opisthokonta). In particular, some sequences were closely related to those of representatives of eukaryotic parasites, such as Phagomyxa and Cryothecomonas of Cercozoa, Pirsonia of stramenopiles and Ichthyosporea of Opisthokonta, although it is not clear whether the organisms occur in free-living or parasitic forms. In addition, other sequences did not seem to be related to any described eukaryotic lineages suggesting the existence of novel eukaryotes at a high-taxonomic level in the sediment. The community composition of microbial eukaryotes in the sediment we surveyed was different overall from those of other anoxic marine environments previously investigated.

  20. Kinetics Study of Uranium and Iodine Transport Across The Marine Sediment-water Interface.

    NASA Astrophysics Data System (ADS)

    Simonucci, C.; Viollier, E.; Jézéquel, D.; Sarazin, G.; Metzger, E.; Prévot, F.; Anschutz, P.; Bouran, J. J.

    Even if extensive lab and fieldwork has been done to determine geo- or biogeochemical reactions that precipitate uranium ore, dominant pathways of uranium accumulation in anoxic marine sediments remain to be demonstrated. As well iodine transformation below sediment-water interface lacks of definitive explanation. In this work, we utilize bioreactors for undisturbed sediment to validate possible mechanisms and extract kinetics information that applies to in situ conditions in order to feed diagenetic model. Here, we are presenting our first results in uranium and iodine from our study sites in the Bay of Biscay (France) and in the Thau lagoon (France). We observe that uranium is trapped in anoxic marine sediments (cores from Bay of Biscay) during our bioreactor experiment under anoxic conditions. The concentration of uranium decreases drastically from the injection concentration, to almost zero, in 20 hours. For iodine, it is not as clear as for uranium, because the concentration is still the same from the beginning of circulation of the injection solution, until the end of the experiment (96 hours). In order to decide wether iodine is trapped in marine sediments or transformed in one of its compounds, we also study its speciation at the reactor output.

  1. Electricity generation by anaerobic bacteria and anoxic sediments from hypersaline soda lakes.

    PubMed

    Miller, Laurence G; Oremland, Ronald S

    2008-11-01

    Anaerobic bacteria and anoxic sediments from soda lakes produced electricity in microbial fuel cells (MFCs). No electricity was generated in the absence of bacterial metabolism. Arsenate respiring bacteria isolated from moderately hypersaline Mono Lake (Bacillus selenitireducens), and salt-saturated Searles Lake, CA (strain SLAS-1) oxidized lactate using arsenate as the electron acceptor. However, these cultures grew equally well without added arsenate using the MFC anode as their electron acceptor, and in the process oxidized lactate more efficiently. The decrease in electricity generation by consumption of added alternative electron acceptors (i.e. arsenate) which competed with the anode for available electrons proved to be a useful indicator of microbial activity and hence life in the fuel cells. Shaken sediment slurries from these two lakes also generated electricity, with or without added lactate. Hydrogen added to sediment slurries was consumed but did not stimulate electricity production. Finally, electricity was generated in statically incubated "intact" sediment cores from these lakes. More power was produced in sediment from Mono Lake than from Searles Lake, however microbial fuel cells could detect low levels of metabolism operating under moderate and extreme conditions of salt stress.

  2. Electricity generation by anaerobic bacteria and anoxic sediments from hypersaline soda lakes

    USGS Publications Warehouse

    Miller, L.G.; Oremland, R.S.

    2008-01-01

    Anaerobic bacteria and anoxic sediments from soda lakes produced electricity in microbial fuel cells (MFCs). No electricity was generated in the absence of bacterial metabolism. Arsenate respiring bacteria isolated from moderately hypersaline Mono Lake (Bacillus selenitireducens), and salt-saturated Searles Lake, CA (strain SLAS-1) oxidized lactate using arsenate as the electron acceptor. However, these cultures grew equally well without added arsenate using the MFC anode as their electron acceptor, and in the process oxidized lactate more efficiently. The decrease in electricity generation by consumption of added alternative electron acceptors (i.e. arsenate) which competed with the anode for available electrons proved to be a useful indicator of microbial activity and hence life in the fuel cells. Shaken sediment slurries from these two lakes also generated electricity, with or without added lactate. Hydrogen added to sediment slurries was consumed but did not stimulate electricity production. Finally, electricity was generated in statically incubated "intact" sediment cores from these lakes. More power was produced in sediment from Mono Lake than from Searles Lake, however microbial fuel cells could detect low levels of metabolism operating under moderate and extreme conditions of salt stress. ?? 2008 US Government.

  3. [Bacterial diversity in Lianyungang marine sediment and Qinghai Lake sediment].

    PubMed

    Hou, Mei-Feng; He, Shi-Long; Li, Dong; Zhang, Jie; Zhao, Yun

    2011-09-01

    The 16S rRNA clone libraries of two different saline environments the Lianyungang marine sediment and the Qinghai Lake sediment were constructed. The Shannon diversity index, Chao and ACE richness index and Simpson dominance index of the bacterial communities in the two samples was compared, and the analysis for the bacterial community structures of this two samples was conducted. The results showed that the Shannon diversity index of Lianyungang marine sediment achieved 3.53, and that of Qinghai Lake sediment achieved 3.05, it was concluded that the bacterial communities in the two samples were diverse. The main bacterial communities in Lianyungang marine sediment included Proteobacteria (49.2%) and Bacteroidetes (29.2%), and Bacteroidetes (60.0%) and Firmicutes (26.0%) were the main bacterial communities in Qinghai Lake sediment. Some halotolerant and halophilic bacteria were found, which were important for industrial production and high saline wastewater treatment.

  4. Isotope fractionation and isotope decoupling during nitrate reduction in marine sediments

    NASA Astrophysics Data System (ADS)

    Dähnke, Kirstin; Thamdrup, Bo

    2015-04-01

    In summer 2010, we sampled marine sediments in the Skagerrak, covering a gradient of reactivity, oxygen consumption, and manganese concentration in the sediment. Along this gradient, we aimed to evaluate links between nitrogen cycling and sediment properties. The focus of the study was the interplay of nitrate and nitrite reduction rates and concomitant nitrate and nitrite isotope changes in sediment incubations. As expected, nitrate reduction was fastest in sediments with highest sediment reactivity and oxygen consumption. At the shallower sampling sites, denitrification was the main removal pathway of nitrate and nitrite, but acetylene inhibition experiments pointed towards significant importance of anammox at the deepest site in the Skagerrak. The N-isotope of denitrification effect varied with depth, with stronger N-isotope fractionation at deeper, and less reactive, sites, and ranged from -12 to -16o. At the deepest site in the Skagerrak, anammox was the dominant N2 production pathway. For this site, we calculated the intrinsic isotope effect of anammox in marine sediments, and found that it is ~-15o, which is in accordance with recent culture studies. The isotope effect of oxygen, however, was not consistent pattern along the gradient of sediment reactivity. The oxygen isotope effect of nitrate reduction was entirely decoupled from the nitrogen isotope effect. Surprisingly, this variability in oxygen isotope fractionation was not linked to the occurrence of anammox, but rather to intermediate nitrite accumulation in the anoxic incubations. Consequently, the ratio of 18ɛ / 15ɛ was highly variable in all sediments we investigated. We presume that such decoupling of oxygen and nitrogen isotopes is due to anoxic nitrite oxidation, which rises in turn with nitrite accumulation in the sediment incubations. These findings suggest that the ratio of 18ɛ / 15ɛ in marine environments is highly flexible, and might, especially in regions with considerable nitrite

  5. Formation of methane and carbon dioxide from dimethylselenide in anoxic sediments and by a methanogenic bacterium

    USGS Publications Warehouse

    Oremland, Ronald S.; Zehr, Jon P.

    1986-01-01

    Anaerobic San Francisco Bay salt marsh sediments rapidly metabolized [14C]dimethylselenide (DMSe) to 14CH4 and 14CO2. Addition of selective inhibitors (2-bromoethanesulfonic acid or molybdate) to these sediments indicated that both methanogenic and sulfate-respiring bacteria could degrade DMSe to gaseous products. However, sediments taken from the selenium-contaminated Kesterson Wildlife Refuge produced only 14CO2 from [14C]DMSe, implying that methanogens were not important in the Kesterson samples. A pure culture of a dimethylsulfide (DMS)-grown methylotrophic methanogen converted [14C]DMSe to 14CH4 and14CO2. However, the organism could not grow on DMSe. Addition of DMS to either sediments or the pure culture retarded the metabolism of DMSe. This effect appeared to be caused by competitive inhibition, thereby indicating a common enzyme system for DMS and DMSe metabolism. DMSe appears to be degraded as part of the DMS pool present in anoxic environments. These results suggest that methylotrophic methanogens may demethylate methylated forms of other metals and metalloids found in nature.

  6. Anoxic Oxidation of Arsenite Linked to Denitrification in Sludges and Sediments

    PubMed Central

    Sun, Wenjie; Sierra, Reyes; Field, Jim A.

    2008-01-01

    In this study, denitrification linked to the oxidation of arsenite (As(III)) to arsenate (As(V)) was shown to be a widespread microbial activity in anaerobic sludge and sediment samples that were not previously exposed to arsenic contamination. When incubated with 0.5 mM As(III) and 10 mM NO3−, the anoxic oxidation of As(III) commenced within a few days, achieving specific activities of up to 1.24 mmol As(V) formed g−1 volatile suspended solids d−1 due to growth (doubling times of 0.74 to 1.4 d). The anoxic oxidation of As(III) was partially to completely inhibited by 1.5 and 5 mM As(III), respectively. Inhibition was minimized by adding As(III) adsorbed onto activated aluminum (AA). The oxidation of As(III) was shown to be linked to the complete denitrification of NO3− to N2 by demonstrating a significantly enhanced production of N2 beyond the background endogenous production as a result of adding As(III)-AA to the cultures. The N2 production corresponded closely the expected stoichiometry of the reaction, 2.5 mol As(III) mol−1 N2-N. The oxidation of As(III) linked to the use of common occuring nitrate as an electron acceptor may be an important missing link in the biogeochemical cycling of arsenic. PMID:18762312

  7. Authigenic phases and biomass contents drive Zr, Hf and REE distributions in anoxic lake sediments

    NASA Astrophysics Data System (ADS)

    Censi, P.; Saiano, F.; Zuddas, P.; Nicosia, A.; Mazzola, S.; Raso, M.

    2013-05-01

    REE, Zr and Hf distributions in seafloor sediments collected from the hypersaline, anoxic Thetis, Kryos, Medee and Tyro deep-sea basins from the Eastern Mediterranean were determined in light of their mineralogical composition, and biomass contents. Mineralogical investigations demonstrate that all the studied sediments show a similar mineralogy. Detritic assemblages mainly consist of quartz, gypsum and calcite with Mg contents ranging from 0 to about 7%, often of a bioclastic nature. On the contrary, authigenic parageneses are formed by halite, bischofite, dolomite and calcite, with Mg contents up to 22%. Textural evidences of biological activity were also identified. In sediments from the Medee and Tyro basins, REE, Zr and Hf distributions were analysed in the fraction soluble in nitric acid, whereas in materials coming from the Thetis and Kryos basins, the water-soluble sediment fraction had been previously removed and REE, Zr and Hf distributions were investigated in the residue. This approach evidenced that shale-normalised REE patterns of the whole fraction soluble in nitric acid show strong intermediate REE (MREE) enrichments that give way to positive Gd anomalies once water-soluble minerals are removed. Y/Ho ratios are clustered around chondritic values justified by the occurrence of detritic minerals whereas Zr/Hf values span a~wider range from slightly subchondritic to superchondritic terms. Negative Gd anomalies, subchondritic Y/Ho and Zr/Hf values are found in Mg-carbonate rich samples suggesting that authigenic Mg-carbonates partition Ho and Hf with respect to Y and Zr during their crystallization from brines. Textural observations and biomass analyses highlighted effects of biological activities in sediments involving Zr and Hf enrichments and the highest Zr/Hf values according to the preferential Zr removal onto biological surfaces, without partitioning Y with respect to Ho. These first data suggest that Zr/Hf ratio and REE distributions can

  8. Isolation of cellulolytic actinomycetes from marine sediments

    SciTech Connect

    Veiga, M.; Esparis, A.; Fabregas, J.

    1983-07-01

    The cellulolytic activity of 36 actinomycetes strains isolated from marine sediments was investigated by the cellulose-azure method. Approximately 50% of the isolates exhibited various degrees of cellulolytic activity. 13 references.

  9. Bacterial ethane formation from reduced, ethylated sulfur compounds in anoxic sediments

    USGS Publications Warehouse

    Oremland, R.S.; Whiticar, Michael J.; Strohmaier, F.E.; Kiene, R.P.

    1988-01-01

    Trace levels of ethane were produced biologically in anoxic sediment slurries from five chemically different aquatic environments. Gases from these locations displayed biogenic characteristics, having 12C-enriched values of ??13CH4 (-62 to -86%.), ??13C2H6 (-35 to -55%.) and high ratios (720 to 140,000) of CH4 [C2H6 + C3H8]. Endogenous production of ethane by slurries was inhibited by autoclaving or by addition of the inhibitor of methanogenic bacteria, 2-bromoethanesulfonic acid (BES). Ethane formation was stimulated markedly by ethanethiol (ESH), and, to a lesser extent, by diethylsulfide (DES). Formation of methane and ethane in ESH- or DES-amended slurries was blocked by BES. Experiments showed that ethionine (or an analogous compound) could be a precursor of ESH. Ethylamine or ethanol additions to slurries caused only a minor stimulation of ethane formation. Similarly, propanethiol additions resulted in only a minor enhancement of propane formation. Cell suspensions of a methyltrophic methanogen produced traces of ethane when incubated in the presence of DES, although the organism did not grow on this compound. These results indicate that methanogenic bacteria produce ethane from the traces of ethylated sulfur compounds present in recent sediments. Preliminary estimates of stable carbon isotope fractionation associated with sediment methane formation from dimethylsulfide was about 40%., while ethane formation from DES and ESH was only 4. 6 and 6.5%., respectively. ?? 1988.

  10. Stable carbon isotope discrimination and microbiology of methane formation in tropical anoxic lake sediments

    NASA Astrophysics Data System (ADS)

    Conrad, R.; Noll, M.; Claus, P.; Klose, M.; Bastos, W. R.; Enrich-Prast, A.

    2010-11-01

    Methane is an important end product of degradation of organic matter in anoxic lake sediments. Methane is mainly produced by either reduction of CO2 or cleavage of acetate involving different methanogenic archaea. The contribution of the different methanogenic paths and of the diverse bacteria and archaea involved in CH4 production exhibits a large variability that is not well understood. Lakes in tropical areas, e.g. in Brazil, are wetlands with high potential impact on the global CH4 budget. However, they have hardly been studied with respect to methanogenesis. Therefore, we used samples from 16 different lake sediments in the Pantanal and Amazon region of Brazil to measure production of CH4, CO2, analyze the content of 13C in the products and in intermediately formed acetate, determine the abundance of bacterial and archaeal microorgansisms and their community composition and diversity by targeting the genes of bacterial and archaeal ribosomal RNA and of methyl coenzyme M reductase, the key enzyme of methanogenic archaea. These experiments were done in the presence and absence of methyl fluoride, an inhibitor of acetoclastic methanogenesis. While production rates of CH4 and CO2 were correlated to the content of organic matter and the abundance of archaea in the sediment, values of 13C in acetate and CH4 were related to the 13C content of organic matter and to the path of CH4 production with its intrinsic carbon isotope fractionation. Isotope fractionation was small (average 10‰) for conversion of Corg to acetate-methyl, which was hardly further fractionated during CH4 production. However, fractionation was strong for CO2 conversion to CH4 (average 75‰), which generally accounted for >50% of total CH4 production. Canonical correspondence analysis did not reveal an effect of microbial community composition, despite the fact that it exhibited a pronounced variability among the different sediments.

  11. Stable carbon isotope discrimination and microbiology of methane formation in tropical anoxic lake sediments

    NASA Astrophysics Data System (ADS)

    Conrad, R.; Noll, M.; Claus, P.; Klose, M.; Bastos, W. R.; Enrich-Prast, A.

    2011-03-01

    Methane is an important end product of degradation of organic matter in anoxic lake sediments. Methane is mainly produced by either reduction of CO2 or cleavage of acetate involving different methanogenic archaea. The contribution of the different methanogenic paths and of the diverse bacteria and archaea involved in CH4 production exhibits a large variability that is not well understood. Lakes in tropical areas, e.g. in Brazil, are wetlands with high potential impact on the global CH4 budget. However, they have hardly been studied with respect to methanogenesis. Therefore, we used samples from 16 different lake sediments in the Pantanal and Amazon region of Brazil to measure production of CH4, CO2, analyze the content of 13C in the products and in intermediately formed acetate, determine the abundance of bacterial and archaeal microorgansisms and their community composition and diversity by targeting the genes of bacterial and archaeal ribosomal RNA and of methyl coenzyme M reductase, the key enzyme of methanogenic archaea. These experiments were done in the presence and absence of methyl fluoride, an inhibitor of acetoclastic methanogenesis. While production rates of CH4 and CO2 were correlated to the content of organic matter and the abundance of archaea in the sediment, values of 13C in acetate, CO2, and CH4 were related to the 13C content of organic matter and to the path of CH4 production with its intrinsic carbon isotope fractionation. Isotope fractionation was small (average 10‰) for conversion of Corg to acetate-methyl, which was hardly further fractionated during CH4 production. However, fractionation was strong for CO2 conversion to CH4 (average 75‰), which generally accounted for >50% of total CH4 production. Canonical correspondence analysis did not reveal an effect of microbial community composition, despite the fact that it exhibited a pronounced variability among the different sediments.

  12. Electric coupling between distant nitrate reduction and sulfide oxidation in marine sediment.

    PubMed

    Marzocchi, Ugo; Trojan, Daniela; Larsen, Steffen; Meyer, Rikke Louise; Revsbech, Niels Peter; Schramm, Andreas; Nielsen, Lars Peter; Risgaard-Petersen, Nils

    2014-08-01

    Filamentous bacteria of the Desulfobulbaceae family can conduct electrons over centimeter-long distances thereby coupling oxygen reduction at the surface of marine sediment to sulfide oxidation in deeper anoxic layers. The ability of these cable bacteria to use alternative electron acceptors is currently unknown. Here we show that these organisms can use also nitrate or nitrite as an electron acceptor thereby coupling the reduction of nitrate to distant oxidation of sulfide. Sulfidic marine sediment was incubated with overlying nitrate-amended anoxic seawater. Within 2 months, electric coupling of spatially segregated nitrate reduction and sulfide oxidation was evident from: (1) the formation of a 4-6-mm-deep zone separating sulfide oxidation from the associated nitrate reduction, and (2) the presence of pH signatures consistent with proton consumption by cathodic nitrate reduction, and proton production by anodic sulfide oxidation. Filamentous Desulfobulbaceae with the longitudinal structures characteristic of cable bacteria were detected in anoxic, nitrate-amended incubations but not in anoxic, nitrate-free controls. Nitrate reduction by cable bacteria using long-distance electron transport to get privileged access to distant electron donors is a hitherto unknown mechanism in nitrogen and sulfur transformations, and the quantitative importance for elements cycling remains to be addressed.

  13. Terrestrial-marine teleconnections in the Devonian: links between the evolution of land plants, weathering processes, and marine anoxic events

    PubMed Central

    Algeo, T. J.

    1998-01-01

    The Devonian Period was characterized by major changes in both the terrestrial biosphere, e.g. the evolution of trees and seed plants and the appearance of multi-storied forests, and in the marine biosphere, e.g. an extended biotic crisis that decimated tropical marine benthos, especially the stromatoporoid-tabulate coral reef community. Teleconnections between these terrestrial and marine events are poorly understood, but a key may lie in the role of soils as a geochemical interface between the lithosphere and atmosphere/hydrosphere, and the role of land plants in mediating weathering processes at this interface. The effectiveness of terrestrial floras in weathering was significantly enhanced as a consequence of increases in the size and geographic extent of vascular land plants during the Devonian. In this regard, the most important palaeobotanical innovations were (1) arborescence (tree stature), which increased maximum depths of root penetration and rhizoturbation, and (2) the seed habit, which freed land plants from reproductive dependence on moist lowland habitats and allowed colonization of drier upland and primary successional areas. These developments resulted in a transient intensification of pedogenesis (soil formation) and to large increases in the thickness and areal extent of soils. Enhanced chemical weathering may have led to increased riverine nutrient fluxes that promoted development of eutrophic conditions in epicontinental seaways, resulting in algal blooms, widespread bottomwater anoxia, and high sedimentary organic carbon fluxes. Long-term effects included drawdown of atmospheric pCO2 and global cooling, leading to a brief Late Devonian glaciation, which set the stage for icehouse conditions during the Permo-Carboniferous. This model provides a framework for understanding links between early land plant evolution and coeval marine anoxic and biotic events, but further testing of Devonian terrestrial-marine teleconnections is needed.

  14. Anaerobic ammonium-oxidising bacteria: A biological source of the bacteriohopanetetrol stereoisomer in marine sediments

    NASA Astrophysics Data System (ADS)

    Rush, Darci; Sinninghe Damsté, Jaap S.; Poulton, Simon W.; Thamdrup, Bo; Garside, A. Leigh; Acuña González, Jenaro; Schouten, Stefan; Jetten, Mike S. M.; Talbot, Helen M.

    2014-09-01

    Bacterially-derived bacteriohopanepolyols (BHPs) are abundant, well preserved lipids in modern and paleo-environments. Bacteriohopanetetrol (BHT) is a ubiquitously produced BHP while its less common stereoisomer (BHT isomer) has previously been associated with anoxic environments; however, its biological source remained unknown. We investigated the occurrence of BHPs in Golfo Dulce, an anoxic marine fjord-like enclosure located in Costa Rica. The distribution of BHT isomer in four sediment cores and a surface sediment transect closely followed the distribution of ladderane fatty acids, unique biomarkers for bacteria performing anaerobic ammonium oxidation (anammox). This suggests that BHT isomer and ladderane lipids likely shared the same biological source in Golfo Dulce. This was supported by examining the BHP lipid compositions of two enrichment cultures of a marine anammox species (‘Candidatus Scalindua profunda’), which were found to contain both BHT and BHT isomer. Remarkably, the BHT isomer was present in higher relative abundance than BHT. However, a non-marine anammox enrichment contained only BHT, which explains the infrequence of BHT isomer observations in terrestrial settings, and indicates that marine anammox bacteria are likely responsible for at least part of the environmentally-observed marine BHT isomer occurrences. Given the substantially greater residence time of BHPs in sediments, compared to ladderanes, BHT isomer is a potential biomarker for past anammox activity.

  15. Anaerobic propane oxidation in marine hydrocarbon seep sediments

    NASA Astrophysics Data System (ADS)

    Quistad, Steven D.; Valentine, David L.

    2011-04-01

    Propane (C 3H 8) is an abundant hydrocarbon in subsurface reservoirs with significance to atmospheric chemistry and to marine biogeochemistry. The anaerobic oxidation of propane coupled to sulfate reduction may prevent sub-seafloor accumulations of propane from entering the ocean and atmosphere. Anaerobic oxidation of propane has recently been demonstrated in cultures of novel sulfate-reducing bacteria, but has not been directly demonstrated or quantified in nature. In this work we describe a method involving incubation with 13C-propane to quantify rates of anaerobic oxidation of propane in anoxic sediment, and we conclusively demonstrate the oxidation of propane under sulfidic conditions in fresh sediments of a marine hydrocarbon seep. Observed rates of anaerobic oxidation of propane adhere to first-order kinetic behavior, enabling the modification of this method for whole core rate determinations. Whole core rates in nine cores from two hydrocarbon seeps measured 0.04-2100 nmoles C 3H 8 cm -3 day -1 by this method. The seep persistently supplied with more propane displayed substantially higher rates of anaerobic oxidation of propane, by 1-2 orders of magnitude when averaged over the top 10-cm, suggesting the development of the microbial community is strongly modulated by the availability of propane. This work is the first to estimate rates for anaerobic oxidation of propane in any environment, and demonstrates the potential importance of the process as a filter for preventing propane from entering the ocean and atmosphere.

  16. Stable carbon isotope discrimination and microbiology of methane formation in tropical anoxic lake sediments

    NASA Astrophysics Data System (ADS)

    Conrad, R.; Noll, M.; Claus, P.; Klose, M.; Enrich-Prast, A.

    2010-12-01

    Methane is an important end product of degradation of organic matter in anoxic lake sediments. Methane is produced by either reduction of CO2 or cleavage of acetate involving different methanogenic archaea. The contribution of the different methanogenic paths and of the diverse bacteria and archaea involved in CH4 production exhibits a large variability that is not well understood. Lakes in tropical areas, e.g. in Brazil, are wetlands with high potential impact on the global CH4 budget. However, they have hardly been studied with respect to methanogenesis. Therefore, we used samples from 16 different lake sites in the Pantanal and Amazon region of Brazil to measure production of CH4, CO2, analyze the content of 13C in the products and in intermediately formed acetate, determine the abundance of bacterial and archaeal microorganisms and their community composition and diversity by targeting the genes of bacterial and archaeal ribosomal RNA and of methyl coenzyme M reductase, the key enzyme of methanogenic archaea. These experiments were done in the presence and absence of methyl fluoride, an inhibitor of acetoclastic methanogenesis. While production rates of CH4 and CO2 were correlated to the content of organic matter and the abundance of archaea in the sediment, values of 13C in acetate and CH4 were related to the 13C content of organic matter and to the path of CH4 production with its intrinsic carbon isotope fractionation. Isotope fractionation was small (average 10‰) for conversion of C-org to acetate-methyl, which was hardly further fractionated during CH4 production. However, fractionation was strong for CO2 conversion to CH4 (average 75‰), which generally accounted for >50% of total CH4 production. Canonical correspondence analysis did not reveal an effect of microbial community composition, despite the fact that it exhibited a pronounced variability among the different sediments.

  17. Microbial community structures in anoxic freshwater lake sediment along a metal contamination gradient.

    PubMed

    Gough, Heidi L; Stahl, David A

    2011-03-01

    Contamination, such as by heavy metals, has frequently been implicated in altering microbial community structure. However, this association has not been extensively studied for anaerobic communities, or in freshwater lake sediments. We investigated microbial community structure in the metal-contaminated anoxic sediments of a eutrophic lake that were impacted over the course of 80 years by nearby zinc-smelting activities. Microbial community structure was inferred for bacterial, archaeal and eukaryotic populations by evaluating terminal restriction fragment length polymorphism (TRFLP) patterns in near-surface sediments collected in triplicate from five areas of the lake that had differing levels of metal contamination. The majority of the fragments in the bacterial and eukaryotic profiles showed no evidence of variation in association with metal contamination levels, and diversity revealed by these profiles remained consistent even as metal concentrations varied from 3000 to 27,000 mg kg(-1) total Zn, 0.125 to 11.2 μ pore water Zn and 0.023 to 5.40 μM pore water As. Although most archaeal fragments also showed no evidence of variation, the prevalence of a fragment associated with mesophilic Crenarchaeota showed significant positive correlation with total Zn concentrations. This Crenarchaeota fragment dominated the archaeal TRFLP profiles, representing between 35% and 79% of the total measured peak areas. Lake DePue 16S rRNA gene sequences corresponding to this TRFLP fragment clustered with anaerobic and soil mesophilic Crenarchaeota sequences. Although Crenarchaeota have been associated with metal-contaminated groundwater and soils, this is a first report (to our knowledge) documenting potential increased prevalence of Crenarchaeota associated with elevated levels of metal contamination.

  18. Accumulation and preservation of organic carbon in marine sediments: The roles of anoxia vs. production

    SciTech Connect

    Calvert, S.E.; Pedersen, T.F. )

    1990-05-01

    Organic carbon enrichments in marine sediments and sedimentary rocks commonly are explained by the preferential preservation of the deposited organic matter under anoxic conditions; the role of primary organic (plankton) production is seldom considered. A review of the available information shows that modern marine sediment accumulating in oxic and anoxic basins in similar topographic and sedimentary settings have very similar carbon contents. On continental slopes, carbon maxima are apparently produced by the complex interplay between the supply of carbon to the sea floor, the texture of the sediment, the dilution of carbon by other sediment components, and the decreasing settling flux of carbon in the deeper waters of the open ocean. Contrary to contemporary thought, there is no causal relationship between such maxima and the position of the oxygen minimum. The degradation of sedimentary organic matter by aerobes and by sulfate reducers is very similar where the supply of fresh organic matter to the sea floor is similar. Hence, there is no evidence for the preferential preservation of organic matter under anoxic conditions. Terrestrial organic matter, however, appears to be degraded to a lesser extent by sulfate reducers. The burial of carbon below the surficial, oxygenated horizons of a sediment removes the easily oxidized fractions leaving material that may be less susceptible to attack by sulfate reducers. Sedimentary carbon maxima in Pleistocene glacial horizons are due to the increased settling flux of organic matter brought about by climatically induced increases in upwelling in the equatorial and marginal areas of the ocean. Changes in bottom water oxygen levels during these periods plays a minor role in producing these signals. Previous work that claimed that anoxic bottom waters were prevalent during the accumulation of organic-rich black shales in the geological record should be reevaluated.

  19. Microbial Reduction of Elemental Selenium to Selenide in Anoxic Sediments - A XANES Study

    NASA Astrophysics Data System (ADS)

    Herbel, M. J.; Switzer Blum, J.; Borglin, S. E.; Oremland, R. S.

    2002-12-01

    Elemental selenium [Se(0)] is the dominant species of selenium present in anoxic sediments. The forms of Se in sedimentary rocks similarly contain high proportions of Se(0), but much of the Se is also in the form of metal selenides, Se(-II). It is not clear if the occurrence of these selenides is due to microbial reduction of Se(0), or a purely chemical process. In this study, we examined the Se redox state of San Francisco Bay sediments that were amended with chemically-formed amorphous Se(0) [Se(0)Chem], biologically-formed amorphous Se(0) [Se(0)Biol], chemically formed black crystalline Se(0) [Se(0)Black] and selenite [Se(IV)] by analyzing the Se XANES spectra in the region 12620-12700 eV. Additions of lactate were used to stimulate activity, while formalin was used as a poisoned control. Samples of the sediment slurries were taken over a period of 95 d. The sediments were centrifuged and loaded into acrylic sample holders in an anaerobic chamber. The sample spectra were fitted with up to three standards with the R-Space X-ray Absorption Package. The standards providing the best fits to the samples were the Se(0) form added to the sediments, selenocystine, FeSe(-II), and Se(IV). For samples amended with Se(0)Chem, first order Se(0) reduction rate constants ranged between 0.11 to 0.025 d-1, and only slight stimulation was found in lactate amended samples. A slightly higher initial reduction rate constant was found for samples amended with Se(0)Biol, while rapid reduction of Se(IV) to Se(0) and selenocystine was observed in the sample with Se(IV). No change in the Se(0) spectrum was observed for samples killed with formalin. The significant proportion of sedimentary Se(-II) as revealed by Se XANES spectra compared to freely soluble Se(-II) concentrations measured by ICP-MS or acid volatile Se(-II) indicates most of the reduced Se was present in the solid form. These results confirm our earlier findings that bacteria are capable of reducing Se(0) to Se(-II), and

  20. Natural abundances of carbon isotopes in acetate from a coastal marine sediment

    NASA Technical Reports Server (NTRS)

    Blair, N. E.; Martens, C. S.; Des Marais, D. J.

    1987-01-01

    Measurements of the natural abundances of carbon isotopes were made in acetate samples isolated from the anoxic marine sediment of Cape Lookout Bight, North Carolina. The typical value of the total acetate carbon isotope ratio (delta 13C) was -16.1 +/- 0.2 per mil. The methyl and carboxyl groups were determined to be -26.4 +/- 0.3 and -6.0 +/- 0.3 per mil, respectively, for one sample. The isotopic composition of the acetate is thought to have resulted from isotopic discriminations that occurred during the cycling of that molecule. Measurements of this type, which have not been made previously in the natural environment, may provide information about the dominant microbial pathways in anoxic sediments as well as the processes that influence the carbon isotopic composition of biogenic methane from many sources.

  1. The chromium isotope composition of reducing and oxic marine sediments

    NASA Astrophysics Data System (ADS)

    Gueguen, Bleuenn; Reinhard, Christopher T.; Algeo, Thomas J.; Peterson, Larry C.; Nielsen, Sune G.; Wang, Xiangli; Rowe, Harry; Planavsky, Noah J.

    2016-07-01

    The chromium (Cr) isotope composition of marine sediments has the potential to provide new insights into the evolution of Earth-surface redox conditions. There are significant but poorly constrained isotope fractionations associated with oxidative subaerial weathering and riverine transport, the major source of seawater Cr, and with partial Cr reduction during burial in marine sediments, the major sink for seawater Cr. A more comprehensive understanding of these processes is needed to establish global Cr isotope mass balance and to gauge the utility of Cr isotopes as a paleoredox proxy. For these purposes, we investigated the Cr isotope composition of reducing sediments from the upwelling zone of the Peru Margin and the deep Cariaco Basin. Chromium is present in marine sediments in both detrital and authigenic phases, and to estimate the isotopic composition of the authigenic fraction, we measured δ53Cr on a weakly acid-leached fraction in addition to the bulk sediment. In an effort to examine potential variability in the Cr isotope composition of the detrital fraction, we also measured δ53Cr on a variety of oxic marine sediments that contain minimal authigenic Cr. The average δ53Cr value of the oxic sediments examined here is -0.05 ± 0.10‰ (2σ, n = 25), which is within the range of δ53Cr values characteristic of the bulk silicate Earth. This implies that uncertainty in estimates of authigenic δ53Cr values based on bulk sediment analyses is mainly linked to estimation of the ratio of Cr in detrital versus authigenic phases, rather than to the Cr-isotopic composition of the detrital pool. Leaches of Cariaco Basin sediments have an average δ53Cr value of +0.38 ± 0.10‰ (2σ, n = 7), which shows no dependency on sample location within the basin and is close to that of Atlantic deepwater Cr (∼+0.5‰). This suggests that authigenic Cr in anoxic sediments may reliably reflect the first-order Cr isotope composition of deepwaters. For Peru Margin samples

  2. Magnesium Isotopic Composition of Subducting Marine Sediments

    NASA Astrophysics Data System (ADS)

    Hu, Y.; Teng, F. Z.; Plank, T. A.; Huang, K. J.

    2015-12-01

    Subducted marine sediments have recently been called upon to explain the heterogeneous Mg isotopic composition (δ26Mg, ‰) found in mantle wehrlites (-0.39 to +0.09 [1]) in the context of a homogeneous mantle (-0.25 ± 0.07 [2]). However, no systematic measurements of δ26Mg on marine sediments are currently available to provide direct support to this model. To characterize the Mg inputs to global subduction zones, we measured δ26Mg data for a total of 90 marine sediments collected from 12 drill sites outboard of the world's major subduction zones. These sediments span a 1.73‰ range in δ26Mg. The detritus-dominated sediments have δ26Mg (-0.59 to +0.53) comparable to those of weathered materials on continents (e.g. -0.52 to +0.92 [3]), while the calcareous oozes yield δ26Mg (as light as -1.20) more similar to the seawater value (-0.83 [4]). The negative correlation between δ26Mg and CaO/Al2O3 in these sediments indicates the primary control of mineralogy over the Mg isotopic distribution among different sediment types, as carbonates are enriched in light Mg isotopes (-5.10 to -0.40 [5]) whereas clay-rich weathering residues generally have heavier δ26Mg (e.g. up to +0.65 in saprolite [6]). In addition, chemical weathering and grain-size sorting drive sediments to a heavier δ26Mg, as indicated by the broad positive trends between δ26Mg with CIA (Chemical Index of Alteration [7]) and Al2O3/SiO2, respectively. Collectively, the arc systems sampled in this study represent ~30% of global arc length and the extrapolated global Mg flux of subducting marine sediments accounts for ~9% of the yearly Mg riverine input with a flux-weighted average δ26Mg at -0.26. Subduction of these heterogeneous sediments may not cause significant mantle heterogeneity on a global scale, but the highly variable Mg fluxes and δ26Mg of sediments delivered to different trenches are capable of producing local mantle variations. Volcanic rocks sourced from these mantle domains are thus

  3. Massive Expansion of Marine Archaea During The Early Albian Oceanic Anoxic Event 1B

    NASA Astrophysics Data System (ADS)

    Kuypers, M. M.; Kuypers, M. M.; Blokker, P.; Erbacher, J.; Kinkel, H.; Pancost, R. D.; Pancost, R. D.; Schouten, S.; Sinninghe Damsté, J. S.

    2001-12-01

    Oceanic anoxic events (OAEs), periods of globally enhanced burial of organic matter (OM) in the marine realm, played an important role in the mid-Cretaceous `greenhouse climate' by effectively reducing atmospheric carbon dioxide concentrations. It is generally believed that these OAEs were caused either by decreased remineralisation or increased production of phytoplanktonic OM. Here we show that enhanced organic carbon (OC) burial during the early Albian OAE1b (~112 My) was caused by a different process. Combined biogeochemical and stable carbon isotopic analyses indicate that black shales from this period contain up to 80% of OC derived from archaea. Archaea-derived isoprenoidal tetraether membrane lipids and free and macromolecularly bound isoprenoid alkanes are abundantly present in these black shales. More specifically the presence of certain ether lipids (cyclic biphytane tetraethers) indicates representatives of the pelagic archaea. To the best of our knowledge this is the earliest fossil evidence for marine planktonic archaea, extending their geological record by more than 60 million years. The diversity of archaeal lipids recovered from the OAE1b black shales suggests that they derive from a multitude of archaeal species. However, the specific 13C enrichment of all such lipids indicates a common `heavy' (13C-rich) carbon source for the archaea and/or a common pathway of carbon-fixation with a reduced 13C fractionation effect compared to the Calvin cycle used by algae, cyanobacteria and higher plants. The large differences (up to 12%) in 13C/12C ratios between the algal biomarkers and the much more abundant archaeal molecular fossils suggest that the latter were not living heterotrophically on photoautotrophic biomass. It seems likely that the archaea present during OAE1b used a chemical energy source (possibly ammonium) for carbon fixation since photoautotrophy within the domain of the Archaea is restricted to only a few species from hypersaline

  4. Abundant Atribacteria in deep marine sediment from the Adélie Basin, Antarctica

    PubMed Central

    Carr, Stephanie A.; Orcutt, Beth N.; Mandernack, Kevin W.; Spear, John R.

    2015-01-01

    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. In this study of deep sediment from Antarctica’s Adélie Basin, collected during Expedition 318 of the Integrated Ocean Drilling Program (IODP), Atribacteria-related sequences of the 16S rRNA gene were abundant (up to 51% of the sequences) and steadily increased in relative abundance with depth throughout the methane-rich zones. To better understand the metabolic potential of Atribacteria within this environment, and to compare with phylogenetically distinct Atribacteria from non-deep-sea environments, individual cells were sorted for single cell genomics from sediment collected from 97.41 m below the seafloor from IODP Hole U1357C. As observed for non-marine Atribacteria, a partial single cell genome suggests 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. This first report of a single cell genome from deep sediment broadens the known diversity within the Atribacteria phylum and highlights the potential role of Atribacteria in carbon cycling in deep sediment. PMID:26379647

  5. Chemical influences on trace metal-sulfide interactions in anoxic sediments

    SciTech Connect

    Morse, J.W.; Luther, G.W. III

    1999-10-01

    Interactions of trace metals with sulfide in anoxic environments are important in determining their chemical form and potential toxicity to organisms. In recent years, a considerable body of observational data has accumulated that indicates very different behavior for various trace metals in sulfidic sediments. These differences in behavior cannot be entirely attributed to thermodynamic relationships, but also reflect differences in ligand exchange reaction kinetics, and redox reaction pathways. Pb, Zn, and Cd, which are generally pyritized to only a few percent of the reactive fraction, have faster water exchange reaction kinetics than Fe{sup 2+}, resulting in MeS phases precipitating prior to FeS formation and subsequent pyrite formation, whereas, Co and Ni, which have slower H{sub 2}O exchange kinetics than Fe{sup 2+}, are incorporated into pyrite. Although Hg and Cu have faster reaction kinetics than Fe{sup 2+}, both are incorporated into pyrite or leached from the pyrite fraction with nitric acid. Hg undergoes significant chloride complexation, which can retard reaction with sulfide, but can also replace Fe in FeS to form HgS, which can only be dissolved in the pyrite fraction. Cu{sup 2+} is reduced by sulfide and forms a variety of sulfides with and without Fe that can only be dissolved with nitric acid. Mn{sup 2+} does not form a MnS phase easily and is incorporated into pyrite at high iron degrees of pyritization (DOP). Oxyanions of Mo and As are first reduced by sulfide. These reduced forms may then react with sulfides resulting in incorporation into pyrite. However, the oxyanion of Cr is reduced to Cr{sup 3+}, which is kinetically inert to reaction with sulfide and, therefore, not incorporated into pyrite.

  6. ENVIRONMENTAL CHARACTERISTICS AFFECTING REDUCTIVE TRANSFORMATION OF ORGANIC POLLUTANTS IN ANOXIC SEDIMENTS

    EPA Science Inventory

    Reductive transformations are important processes for determining the fate of organic pollutants in anoxic environments. These processes are most often microbially mediated by both direct and indirect means. For example, specific bacteria transform organic pollutants directly as ...

  7. Geochemical and anthropogenic enrichments of Mo in sediments from perennially oxic and seasonally anoxic lakes in Eastern Canada

    NASA Astrophysics Data System (ADS)

    Chappaz, Anthony; Gobeil, Charles; Tessier, André

    2008-01-01

    We measured the vertical distributions of Mo, Fe, Mn, sulfide, sulfate, organic carbon, major ions, and pH in sediment porewater from one perennially oxic and three seasonally anoxic lacustrine basins in Eastern Canada, as well as those of Mo, acid volatile sulfide, Fe, Mn, Al, organic C, 210Pb and 137Cs in sediment cores from the same sites. The only input of anthropogenic Mo to these lakes comes from atmospheric deposition. The relatively monotonous distribution of Mo in the porewater of three seasonally anoxic basins suggests that Mo is not redistributed in the sedimentary column during periods of anoxia. In contrast, porewater Mo profiles obtained at three sampling dates in a perennially oxic basin display sharp Mo peaks below the sediment-water interface, indicating redistribution subsequent to deposition. Modeling of these latter porewater Mo profiles with a diagenetic reaction-transport equation coupled to comparisons among the various porewater and solid phase profiles reveal that Mo is released at 1-2 cm depth as a consequence of the reductive dissolution of Fe oxyhydroxides and scavenged both at the vicinity of the sediment-water interface, by re-adsorption onto authigenic Fe oxyhydroxides, and deeper in the sediments where dissolved sulfide concentrations are higher. The estimated rate constant for the adsorption of Mo onto Fe oxyhydroxides is 36 ± 45 cm 3 mol -1 s -1. Diagenetic modeling indicates that authigenic Mo in sediments of the perennially oxic basin represents about one-third of the total solid phase Mo in the first cm below the sediment-water interface and only one tenth below this horizon. If we assume that no authigenic Mo is accumulated in the seasonally anoxic lake sediments we conclude that the sediment Mo concentrations, which are up to 3-16 times higher than the average lithogenic composition, depending on the lake, are mainly due to atmospheric deposition of anthropogenic Mo and not to the formation of authigenic Mo phases

  8. Temperature-driven decoupling of key phases of organic matter degradation in marine sediments

    PubMed Central

    Weston, Nathaniel B.; Joye, Samantha B.

    2005-01-01

    The long-term burial of organic carbon in sediments results in the net accumulation of oxygen in the atmosphere, thereby mediating the redox state of the Earth's biosphere and atmosphere. Sediment microbial activity plays a major role in determining whether particulate organic carbon is recycled or buried. A diverse consortium of microorganisms that hydrolyze, ferment, and terminally oxidize organic compounds mediates anaerobic organic matter mineralization in anoxic sediments. Variable temperature regulation of the sequential processes, leading from the breakdown of complex particulate organic carbon to the production and subsequent consumption of labile, low-molecular weight, dissolved intermediates, could play a key role in controlling rates of overall organic carbon mineralization. We examined sediment organic carbon cycling in a sediment slurry and in flow through bioreactor experiments. The data show a variable temperature response of the microbial functional groups mediating organic matter mineralization in anoxic marine sediments, resulting in the temperature-driven decoupling of the production and consumption of organic intermediates. This temperature-driven decoupling leads to the accumulation of labile, low-molecular weight, dissolved organic carbon at low temperatures and low-molecular weight dissolved organic carbon limitation of terminal metabolism at higher temperatures. PMID:16286654

  9. Cultivation of methanogens from shallow marine sediments at Hydrate Ridge, Oregon

    PubMed Central

    Kendall, Melissa M.; Boone, David R.

    2006-01-01

    Little is known about the methanogenic degradation of acetate, the fate of molecular hydrogen and formate or the ability of methanogens to grow and produce methane in cold, anoxic marine sediments. The microbes that produce methane were examined in permanently cold, anoxic marine sediments at Hydrate Ridge (44°35' N, 125°10' W, depth 800 m). Sediment samples (15 to 35 cm deep) were collected from areas of active methane ebullition or areas where methane hydrates occurred. The samples were diluted into enrichment medium with formate, acetate or trimethylamine as catabolic substrate. After 2 years of incubation at 4 °C to 15 °C, enrichment cultures produced methane. PCR amplification and sequencing of the rRNA genes from the highest dilutions with growth suggested that each enrichment culture contained a single strain of methanogen. The level of sequence similarity (91 to 98%) to previously characterized prokaryotes suggested that these methanogens belonged to novel genera or species within the orders Methanomicrobiales and Methanosarcinales. Analysis of the 16S rRNA gene libraries from DNA extracted directly from the sediment samples revealed phylotypes that were either distantly related to cultivated methanogens or possible anaerobic methane oxidizers related to the ANME-1 and ANME-2 groups of the Archaea. However, no methanogenic sequences were detected, suggesting that methanogens represented only a small proportion of the archaeal. PMID:16877319

  10. Nonlinear compressional waves in marine sediments

    NASA Astrophysics Data System (ADS)

    McDonald, B. Edward

    2005-09-01

    A theory for nonlinear waves in marine sediments must account for the presence of a granular frame filled with water and possibly gas bubbles. When grains are in full contact, the stress-strain relation for the sediment contains a contribution varying as strain to the power 3/2, referred to as the Hertz force. The quadratic nonlinearity parameter derived from the second pressure derivative with respect to density thus diverges in the limit of small strain. We present a simple nonlinear wave equation model (a variant of the NPE) for compressional waves in marine sediments that avoids Taylor expansion and the problem of diverging nonlinearity parameter. An equation of state for partially consolidated sediments is derived from consolidation test results. Pressure is found to increase with overdensity to the power 5/2, indicating an increase in the number of contacts per grain as density increases. Numerical results for nonlinear compressional waves show agreement with analytic self-similar profiles derived from the nonlinear wave equation. [Work supported by the ONR.

  11. Carotenoid diagenesis in a marine sediment

    NASA Technical Reports Server (NTRS)

    Watts, C. D.; Maxwell, J. R.

    1977-01-01

    The major carotenoids at three levels (3, 40, and 175 m below the sediment-water interface) in a core from a marine sediment (Cariaco Trench, off Venezuela) have been examined. Mass and electronic spectral data have provided evidence for the onset of a progressive reduction of carotenoids in the geological column. The time scale of the process appears to depend on the particular carotenoid. Reduction of up to two double bonds is observed for the diol, zeaxanthin, in the oldest sediment (about 340,000 years old) but no reduction is observed in the younger samples (about 5000 and 56,000 years old). The diketone, canthaxanthin, shows evidence of reduction of up to two double bonds in the 56,000-yr sample and up to five double bonds in the oldest sample. No reduction of beta-carotene was observed in any of the samples.

  12. Kinetics of phytoplankton decay during simulated sedimentation: Changes in biochemical composition and microbial activity under oxic and anoxic conditions

    NASA Astrophysics Data System (ADS)

    Harvey, H. Rodger; Tuttle, Jon H.; Bell, J. Tyler

    1995-08-01

    A series of oxic and anoxic incubations examined the decay of two marine phytoplankton, the diatom Thalassiosira weissffogii and the coccoid cyanobacterium Synechococcus sp, in flow-through systems without macrozooplankton grazers. The major biochemical fractions of algal carbon (protein, carbohydrates, and lipid) were quantified over time together with bacterial abundance and activity. Oxic decay constants of bulk and individual biochemical fractions showed good agreement between both phytoplankters, suggesting that composition at the molecular level within a particular biochemical class does not influence decay rate as much as differences among the major biochemical fractions. Large differences in decay rates did exist among biochemical classes, with carbohydrates utilized most rapidly under oxic conditions, followed by protein and then lipid. Turnover times among the particulate pools ranged from 10.7 days for diatom and cyanobacterial carbohydrates under oxic conditions to over 160 days for cyanobacterial lipids under anoxia, with oxygen having a substantial effect on overall rates of algal carbon decomposition. PON values tracked POC with an average POC:PON ratio of 4.99 ± 0.52 for diatoms and 4.48 ± 0.66 for cyanobacteria throughout the experiments. Bacterial abundances and activity varied substantially over the course of the incubations with greatest activity during periods of greatest particulate loss. Bacterial abundances and metabolism were comparable under oxic and anoxic conditions even though the amount of material degraded under anoxic conditions was significantly less than when oxygen was present, suggesting that oxygen increased rates of particulate material degradation.

  13. Succession of cable bacteria and electric currents in marine sediment

    PubMed Central

    Schauer, Regina; Risgaard-Petersen, Nils; Kjeldsen, Kasper U; Tataru Bjerg, Jesper J; B Jørgensen, Bo; Schramm, Andreas; Nielsen, Lars Peter

    2014-01-01

    Filamentous Desulfobulbaceae have been reported to conduct electrons over centimetre-long distances, thereby coupling oxygen reduction at the surface of marine sediment to sulphide oxidation in sub-surface layers. To understand how these ‘cable bacteria' establish and sustain electric conductivity, we followed a population for 53 days after exposing sulphidic sediment with initially no detectable filaments to oxygen. After 10 days, cable bacteria and electric currents were established throughout the top 15 mm of the sediment, and after 21 days the filament density peaked with a total length of 2 km cm−2. Cells elongated and divided at all depths with doubling times over the first 10 days of <20 h. Active, oriented movement must have occurred to explain the separation of O2 and H2S by 15 mm. Filament diameters varied from 0.4–1.7 μm, with a general increase over time and depth, and yet they shared 16S rRNA sequence identity of >98%. Comparison of the increase in biovolume and electric current density suggested high cellular growth efficiency. While the vertical expansion of filaments continued over time and reached 30 mm, the electric current density and biomass declined after 13 and 21 days, respectively. This might reflect a breakdown of short filaments as their solid sulphide sources became depleted in the top layers of the anoxic zone. In conclusion, cable bacteria combine rapid and efficient growth with oriented movement to establish and exploit the spatially separated half-reactions of sulphide oxidation and oxygen consumption. PMID:24451206

  14. Succession of cable bacteria and electric currents in marine sediment.

    PubMed

    Schauer, Regina; Risgaard-Petersen, Nils; Kjeldsen, Kasper U; Tataru Bjerg, Jesper J; B Jørgensen, Bo; Schramm, Andreas; Nielsen, Lars Peter

    2014-06-01

    Filamentous Desulfobulbaceae have been reported to conduct electrons over centimetre-long distances, thereby coupling oxygen reduction at the surface of marine sediment to sulphide oxidation in sub-surface layers. To understand how these 'cable bacteria' establish and sustain electric conductivity, we followed a population for 53 days after exposing sulphidic sediment with initially no detectable filaments to oxygen. After 10 days, cable bacteria and electric currents were established throughout the top 15 mm of the sediment, and after 21 days the filament density peaked with a total length of 2 km cm(-2). Cells elongated and divided at all depths with doubling times over the first 10 days of <20 h. Active, oriented movement must have occurred to explain the separation of O2 and H2S by 15 mm. Filament diameters varied from 0.4-1.7 μm, with a general increase over time and depth, and yet they shared 16S rRNA sequence identity of >98%. Comparison of the increase in biovolume and electric current density suggested high cellular growth efficiency. While the vertical expansion of filaments continued over time and reached 30 mm, the electric current density and biomass declined after 13 and 21 days, respectively. This might reflect a breakdown of short filaments as their solid sulphide sources became depleted in the top layers of the anoxic zone. In conclusion, cable bacteria combine rapid and efficient growth with oriented movement to establish and exploit the spatially separated half-reactions of sulphide oxidation and oxygen consumption.

  15. Anoxic Decomposition in Sediments from a Tropical Mangrove Forest and the Temperate Wadden Sea: Implications of N and P Addition Experiments

    NASA Astrophysics Data System (ADS)

    Holmboe, N.; Kristensen, E.; Andersen, F. Ø.

    2001-08-01

    The anoxic decomposition processes in sediments from a tropical mangrove forest (Bangrong, Thailand) and a salt marsh in the temperate Wadden Sea (Denmark) were compared, and the effects of increased ammonium and/or phosphate concentrations on the anoxic decomposition were studied. Sediment was incubated in jars (20-ml glass vials) and changes in porewater solutes were followed in a time series of 3 weeks. Furthermore, the short-term fate (days) of dissolved inorganic phosphate (DIP) added to Bangrong mangrove sediment was evaluated from phosphorus fractionation. Although the organic matter at both study sites had relatively high C:N and C:P ratios, the anoxic sediment decomposition was not affected by nutrient enrichments at the level applied in this study. The sediment metabolism (TCO 2and DOC production, and sulfate consumption) was 5-10 times higher in Wadden Sea sediment than in Bangrong mangrove sediment, probably due to the higher content of structural carbohydrates (e.g. cellulose) as indicated by higher C:N and C:P ratios in mangrove organic matter. This is substantiated by a lower nutrient release from Bangrong mangrove sediments and suggests a faster turnover of N and P by nutrient deficient bacteria in the mangrove sediment. DIP was released during anoxic decomposition in Wadden Sea sediment, but was retained in Bangrong mangrove sediment. Analysis of phosphorus fractions in Bangrong mangrove sediment revealed that added excess DIP was efficiently taken up by the sediment particles and primarily retrieved in the easily exchangeable and iron bound fractions. The studied mangrove forest sediment seems to be a phosphorus sink.

  16. Radioactive equilibrium in ancient marine sediments

    USGS Publications Warehouse

    Breger, I.A.

    1955-01-01

    Radioactive equilibrium in eight marine sedimentary formations has been studied by means of direct determinations of uranium, radium and thorium. Alpha-particle counting has also been carried out in order to cross-calibrate thick-source counting techniques. The maximum deviation from radioactive equilibrium that has been noted is 11 per cent-indicating that there is probably equilibrium in all the formations analyzed. Thick-source alpha-particle counting by means of a proportional counter or an ionization chamber leads to high results when the samples contain less than about 10 p.p.m. of uranium. For samples having a higher content of uranium the results are in excellent agreement with each other and with those obtained by direct analytical techniques. The thorium contents that have been obtained correspond well to the average values reported in the literature. The uranium content of marine sediments may be appreciably higher than the average values that have been reported for sedimentary rocks. Data show that there is up to fourteen times the percentage of uranium as of thorium in the formations studied and that the percentage of thorium never exceeds that of uranium. While the proximity of a depositional environment to a land mass may influence the concentration of uranium in a marine sediment, this is not true with thorium. ?? 1955.

  17. Anaerobic ammonium oxidation by nitrite (anammox): Implications for N 2 production in coastal marine sediments

    NASA Astrophysics Data System (ADS)

    Engström, Pia; Dalsgaard, Tage; Hulth, Stefan; Aller, Robert C.

    2005-04-01

    The respiratory reduction of nitrate (denitrification) is acknowledged as the most important process that converts biologically available nitrogen to gaseous dinitrogen (N 2) in marine ecosystems. Recent findings, however, indicate that anaerobic ammonium oxidation by nitrite (anammox) may be an important pathway for N 2 formation and N removal in coastal marine sediments and in anoxic water columns of the oceans. In the present study, we explored this novel mechanism during N mineralization by 15N amendments (single and coupled additions of 15NH 4+, 14NO 3- and 15NO 3-) to surface sediments with a wide range of characteristics and overall reactivity. Patterns of 29/30N 2 production in the pore water during closed sediment incubations demonstrated anammox at all 7 of the investigated sites. Stoichiometric calculations revealed that 4% to 79% of total N 2 production was due to this novel route. The relative importance of anammox for N 2 release was inversely correlated with remineralized solute production, benthic O 2 consumption, and surface sediment Chl a. The observed correlations indicate competition between reductants for pore water nitrite during early diagenesis and that additional factors (e.g. availability of Mn-oxides), superimposed on overall patterns of diagenetic activity, are important for determining absolute and relative rates of anammox in coastal marine sediments.

  18. Metabarcoding Marine Sediments: Preparation of Amplicon Libraries.

    PubMed

    Fonseca, Vera G; Lallias, Delphine

    2016-01-01

    The accurate assessment of community composition and ultimately species identification is of utmost importance in any ecological and evolutionary study. Advances in sequencing technologies have allowed the unraveling of levels of biodiversity never imagined before when applied to large-scale environmental DNA studies (also termed metabarcoding/metagenetics/metasystematics/environmental barcoding). Here, we describe a detailed protocol to assess eukaryotic biodiversity in marine sediments, identifying key steps that should not be neglected when preparing Next-Generation Sequencing (NGS) amplicon libraries: DNA extraction, multiple PCR amplification of DNA barcode markers with index/ tag-primers, and final Illumina MiSeq sequencing library preparation. PMID:27460378

  19. Sediment Burial Intolerance of Marine Macroinvertebrates.

    PubMed

    Hendrick, Vicki J; Hutchison, Zoë L; Last, Kim S

    2016-01-01

    The marine environment contains suspended particulate matter which originates from natural and anthropogenic sources. Settlement of this material can leave benthic organisms susceptible to smothering, especially if burial is sudden i.e. following storms or activities such as dredging. Their survival will depend on their tolerance to, and their ability to escape from burial. Here we present data from a multi-factorial experiment measuring burial responses incorporating duration, sediment fraction and depth. Six macroinvertebrates commonly found in sediment rich environments were selected for their commercial and/or conservation importance. Assessments revealed that the brittle star (Ophiura ophiura), the queen scallop (Aequipecten opercularis) and the sea squirt (Ciona intestinalis) were all highly intolerant to burial whilst the green urchin (Psammichinus miliaris) and the anemone (Sagartiogeton laceratus), showed intermediate and low intolerance respectively, to burial. The least intolerant, with very high survival was the Ross worm (Sabellaria spinulosa). With the exception of C. intestinalis, increasing duration and depth of burial with finer sediment fractions resulted in increased mortality for all species assessed. For C. intestinalis depth of burial and sediment fraction were found to be inconsequential since there was complete mortality of all specimens buried for more than one day. When burial emergence was assessed O. ophiura emerged most frequently, followed by P. miliaris. The former emerged most frequently from the medium and fine sediments whereas P. miliaris emerged more frequently from coarse sediment. Both A. opercularis and S. laceratus showed similar emergence responses over time, with A. opercularis emerging more frequently under coarse sediments. The frequency of emergence of S. laceratus increased with progressively finer sediment and C. intestinalis did not emerge from burial irrespective of sediment fraction or depth. Finally, and perhaps

  20. Sediment Burial Intolerance of Marine Macroinvertebrates

    PubMed Central

    Hendrick, Vicki J.; Hutchison, Zoë L.; Last, Kim S.

    2016-01-01

    The marine environment contains suspended particulate matter which originates from natural and anthropogenic sources. Settlement of this material can leave benthic organisms susceptible to smothering, especially if burial is sudden i.e. following storms or activities such as dredging. Their survival will depend on their tolerance to, and their ability to escape from burial. Here we present data from a multi-factorial experiment measuring burial responses incorporating duration, sediment fraction and depth. Six macroinvertebrates commonly found in sediment rich environments were selected for their commercial and/or conservation importance. Assessments revealed that the brittle star (Ophiura ophiura), the queen scallop (Aequipecten opercularis) and the sea squirt (Ciona intestinalis) were all highly intolerant to burial whilst the green urchin (Psammichinus miliaris) and the anemone (Sagartiogeton laceratus), showed intermediate and low intolerance respectively, to burial. The least intolerant, with very high survival was the Ross worm (Sabellaria spinulosa). With the exception of C. intestinalis, increasing duration and depth of burial with finer sediment fractions resulted in increased mortality for all species assessed. For C. intestinalis depth of burial and sediment fraction were found to be inconsequential since there was complete mortality of all specimens buried for more than one day. When burial emergence was assessed O. ophiura emerged most frequently, followed by P. miliaris. The former emerged most frequently from the medium and fine sediments whereas P. miliaris emerged more frequently from coarse sediment. Both A. opercularis and S. laceratus showed similar emergence responses over time, with A. opercularis emerging more frequently under coarse sediments. The frequency of emergence of S. laceratus increased with progressively finer sediment and C. intestinalis did not emerge from burial irrespective of sediment fraction or depth. Finally, and perhaps

  1. Sediment Burial Intolerance of Marine Macroinvertebrates.

    PubMed

    Hendrick, Vicki J; Hutchison, Zoë L; Last, Kim S

    2016-01-01

    The marine environment contains suspended particulate matter which originates from natural and anthropogenic sources. Settlement of this material can leave benthic organisms susceptible to smothering, especially if burial is sudden i.e. following storms or activities such as dredging. Their survival will depend on their tolerance to, and their ability to escape from burial. Here we present data from a multi-factorial experiment measuring burial responses incorporating duration, sediment fraction and depth. Six macroinvertebrates commonly found in sediment rich environments were selected for their commercial and/or conservation importance. Assessments revealed that the brittle star (Ophiura ophiura), the queen scallop (Aequipecten opercularis) and the sea squirt (Ciona intestinalis) were all highly intolerant to burial whilst the green urchin (Psammichinus miliaris) and the anemone (Sagartiogeton laceratus), showed intermediate and low intolerance respectively, to burial. The least intolerant, with very high survival was the Ross worm (Sabellaria spinulosa). With the exception of C. intestinalis, increasing duration and depth of burial with finer sediment fractions resulted in increased mortality for all species assessed. For C. intestinalis depth of burial and sediment fraction were found to be inconsequential since there was complete mortality of all specimens buried for more than one day. When burial emergence was assessed O. ophiura emerged most frequently, followed by P. miliaris. The former emerged most frequently from the medium and fine sediments whereas P. miliaris emerged more frequently from coarse sediment. Both A. opercularis and S. laceratus showed similar emergence responses over time, with A. opercularis emerging more frequently under coarse sediments. The frequency of emergence of S. laceratus increased with progressively finer sediment and C. intestinalis did not emerge from burial irrespective of sediment fraction or depth. Finally, and perhaps

  2. Century-long record of Mo isotopic composition in sediments of a seasonally anoxic estuary (Chesapeake Bay)

    NASA Astrophysics Data System (ADS)

    Scheiderich, K.; Helz, G. R.; Walker, R. J.

    2010-01-01

    A double-spike method was used to obtain Mo isotope data for sediments and waters of the seasonally anoxic Chesapeake Bay, and its primary tributary, the Susquehanna River. The dissolved Mo distribution in the estuary is non-conservative, reflecting minor Mo loss to the sediments, although removal of Mo to the sediments does not have a large influence on the isotopic composition of the water column. The δ98Mo of dissolved Mo in most of the estuary is dominated by seawater. Six samples with salinity > 15 have an average δ98Mo = + 2.17‰ (± 0.12), which agrees well with a δ98Mo value for the CASS-4 seawater standard of + 2.23‰. A single sample of Susquehanna River water has a δ98Mo of + 1.02‰, consistent with recent findings of positive δ98Mo in rivers worldwide. Susquehanna river sediments, in contrast, have δ98Mo ˜ - 0.1‰. The difference between the river water and sediment values implies that isotopic fractionation occurs within the river basin. The δ98Mo values for estuarine sediments are offset from values in the overlying water. Most samples deposited before 1925 have δ98Mo less than 0‰, similar to the Susquehanna sediments. Subsequently, there is an increase in the variability of δ98Mo, with values ranging up to + 0.8‰. The transition to increased variability coincides with the onset of authigenic Mo deposition, which was previously attributed to escalating summertime anoxia. Authigenic Mo concentrations correlate poorly with δ98Mo in core samples, suggesting that independent mechanisms influence the two parameters. Authigenic Mo concentrations may be controlled by shifting pore water H 2S levels, while δ98Mo may be primarily affected by annual variations in Mn refluxing.

  3. Anaerobic degradation of cyclohexane by sulfate-reducing bacteria from hydrocarbon-contaminated marine sediments.

    PubMed

    Jaekel, Ulrike; Zedelius, Johannes; Wilkes, Heinz; Musat, Florin

    2015-01-01

    The fate of cyclohexane, often used as a model compound for the biodegradation of cyclic alkanes due to its abundance in crude oils, in anoxic marine sediments has been poorly investigated. In the present study, we obtained an enrichment culture of cyclohexane-degrading sulfate-reducing bacteria from hydrocarbon-contaminated intertidal marine sediments. Microscopic analyses showed an apparent dominance by oval cells of 1.5 × 0.8 μm. Analysis of a 16S rRNA gene library, followed by whole-cell hybridization with group- and sequence-specific oligonucleotide probes showed that these cells belonged to a single phylotype, and were accounting for more than 80% of the total cell number. The dominant phylotype, affiliated with the Desulfosarcina-Desulfococcus cluster of the Deltaproteobacteria, is proposed to be responsible for the degradation of cyclohexane. Quantitative growth experiments showed that cyclohexane degradation was coupled with the stoichiometric reduction of sulfate to sulfide. Substrate response tests corroborated with hybridization with a sequence-specific oligonucleotide probe suggested that the dominant phylotype apparently was able to degrade other cyclic and n-alkanes, including the gaseous alkane n-butane. Based on GC-MS analyses of culture extracts cyclohexylsuccinate was identified as a metabolite, indicating an activation of cyclohexane by addition to fumarate. Other metabolites detected were 3-cyclohexylpropionate and cyclohexanecarboxylate providing evidence that the overall degradation pathway of cyclohexane under anoxic conditions is analogous to that of n-alkanes.

  4. Anaerobic degradation of cyclohexane by sulfate-reducing bacteria from hydrocarbon-contaminated marine sediments

    PubMed Central

    Jaekel, Ulrike; Zedelius, Johannes; Wilkes, Heinz; Musat, Florin

    2015-01-01

    The fate of cyclohexane, often used as a model compound for the biodegradation of cyclic alkanes due to its abundance in crude oils, in anoxic marine sediments has been poorly investigated. In the present study, we obtained an enrichment culture of cyclohexane-degrading sulfate-reducing bacteria from hydrocarbon-contaminated intertidal marine sediments. Microscopic analyses showed an apparent dominance by oval cells of 1.5 × 0.8 μm. Analysis of a 16S rRNA gene library, followed by whole-cell hybridization with group- and sequence-specific oligonucleotide probes showed that these cells belonged to a single phylotype, and were accounting for more than 80% of the total cell number. The dominant phylotype, affiliated with the Desulfosarcina-Desulfococcus cluster of the Deltaproteobacteria, is proposed to be responsible for the degradation of cyclohexane. Quantitative growth experiments showed that cyclohexane degradation was coupled with the stoichiometric reduction of sulfate to sulfide. Substrate response tests corroborated with hybridization with a sequence-specific oligonucleotide probe suggested that the dominant phylotype apparently was able to degrade other cyclic and n-alkanes, including the gaseous alkane n-butane. Based on GC-MS analyses of culture extracts cyclohexylsuccinate was identified as a metabolite, indicating an activation of cyclohexane by addition to fumarate. Other metabolites detected were 3-cyclohexylpropionate and cyclohexanecarboxylate providing evidence that the overall degradation pathway of cyclohexane under anoxic conditions is analogous to that of n-alkanes. PMID:25806023

  5. Analysis of marine bivalves and sediments

    SciTech Connect

    Zeisler, R.; Stone, S.F.

    1986-01-01

    Recently, environmental monitoring has been complemented by programs for systematic and controlled long-term storage of environmental samples; i.e., environmental specimen banking (ESB). In the US a pilot ESB program is currently expanding to become past of several environmental and human health monitoring projects. The National Status and Trends (NS and T) program on the marine environment, administrated by the National Oceanic and Atmospheric Administration (NOAA), is one of these projects and has initialized new investigations within the ESB research program. This research includes all steps of the ESB operation, with special emphasis on quality assurance in the selection, collection, preparation, storage, and analysis of marine samples according to validated procedures. A unique sequence of instrumental analytical methods involving x-ray fluorescence and neutron activation analysis procedures has been employed for the determination of 44 elements in marine bivalves. The individual procedures are an x-ray fluorescence method based on backscatter with fundamental parameter corrections, prompt gamma activation analysis, and neutron activation analysis with instrumental and radiochemical procedures. This analytical approach has been expanded to include the analysis of sediments and fish tissues.

  6. Boreal organic-rich sediments of Oceanic Anoxic Event 2: dinoflagellate cysts, anoxia and an intensified hydrological cycle

    NASA Astrophysics Data System (ADS)

    Young, Tom; Jarvis, Ian; Dodsworth, Paul; Trabucho-Alexandre, João; Tocher, Bruce; Waller, Martyn

    2014-05-01

    Diverse palynological assemblages have been recovered from Cenomanian-Turonian boundary (CTB) successions in the central North Sea and onshore NE England that contain organic-rich deposits characteristic of Oceanic Anoxic Event 2 (OAE2). The stratigraphic extent of the event is evidenced by a marked positive excursion in δ13Corg profiles. Palynomorphs are absent in the chalks immediately underlying the onset of the positive isotope excursion. Pulses of abundant spores and pollen are associated with the appearance of organic-walled dinoflagellate cysts (dinocysts) in marlier but organic-lean sediments characterizing the early stages of the event. Dinocyst assemblages are indicative of an outer neritic environment, with high abundances of Spiniferites spp. and the presence species such as Pterodinium cornutum. Black shales are confined to the later stages of the CTB interval and the peak of the δ13Corg excursion. These are characterized by abundant Cyclonephelium, which has been reported to be representative of anoxic conditions, but also reduced salinity and lower nutrient environments. Changes of the assemblage from open water species to that of species associated with lower salinity/shallower water environments is coeval with a trend to more negative δ18O values, indicative of increasing water temperature. It is postulated that intensification the hydrological cycle during latest Cenomanian global warming and eustatic sea-level rise, increased the flow of freshwater into the oceans and modified ocean circulation patterns, transporting shallower water species out into open water.

  7. Assessing carbon and nitrogen removal in a novel anoxic-aerobic cyanobacterial-bacterial photobioreactor configuration with enhanced biomass sedimentation.

    PubMed

    de Godos, I; Vargas, V A; Guzmán, H O; Soto, R; García, B; García, P A; Muñoz, R

    2014-09-15

    The carbon and nitrogen removal potential of an innovative anoxic-aerobic photobioreactor configuration operated with both internal and external recyclings was evaluated under different cyanobacterial-bacterial sludge residence times (9-31 days) during the treatment of wastewaters with low C/N ratios. Under optimal operating conditions, the two-stage photobioreactor was capable of providing organic carbon and nitrogen removals over 95% and 90%, respectively. The continuous biomass recycling from the settler resulted in the enrichment and predominance of rapidly-settling cyanobacterial-bacterial flocs and effluent suspended solid concentrations lower than 35 mg VSS L(-1). These flocs exhibited sedimentation rates of 0.28-0.42 m h(-1) but sludge volumetric indexes of 333-430 ml/g. The decoupling between the hydraulic retention time and sludge retention time mediated by the external recycling also avoided the washout of nitrifying bacteria and supported process operation at biomass concentrations of 1000-1500 mg VSS L(-1). The addition of additional NaHCO3 to the process overcame the CO2 limitation resulting from the intense competition for inorganic carbon between cyanobacteria and nitrifying bacteria in the photobioreactor, which supported the successful implementation of a nitrification-denitrification process. Unexpectedly, this nitrification-denitrification process occurred both simultaneously in the photobioreactor alone (as a result of the negligible dissolved oxygen concentrations) and sequentially in the two-stage anoxic-aerobic configuration with internal NO3(-)/NO2(-) recycling. PMID:24880959

  8. MODEL FOR CHANGES IN SEDIMENT AND WATER-COLUMN BIOGEOCHEMISTRY IN RESPONSE TO SEASONALLY HYPOXIC/ANOXIC CONDITIONS BENEATH THE MISSISSIPPI RIVER PLUME

    EPA Science Inventory

    Although the bottom waters of many freshwater and marine environments are either permanently oxic or anoxic, there is a growing appreciation that in many bodies of water near-bottom conditions seasonally oscillate between these extremes. Although observational databases for these...

  9. QSARS for predicting biotic and abiotic reductive transformation rate constants of halogenated hydrocarbons in anoxic sediment systems

    SciTech Connect

    Peijnenburg, W.J.G.M.; 't Hart, M.J.; den Hollander, H.A.; van de Meent, D.; Verboom, H.H.

    1991-01-01

    Quantitative structure-activity relationships (QSARs) are developed relating biotic and abiotic pseudo-first-order disappearance rate constants of halogenated hydrocarbons in anoxic sediments to a number of readily available molecular descriptors. Based upon knowledge of the underlying reaction mechanisms, four descriptors were selected: carbon halogen bond strength, the summation of the Hammett (aromatics) and Taft (aliphatics) sigma constants and the inductive constants (aromatics) of the additional substituents, carbon-carbon bond dissociation energy (aliphatics), and steric factors of the additional substituents. Comparison of the abiotic and biotic QSARs clearly showed the close similarities between both processes. By correlating the rate constants for reduction of a number of halocarbons obtained in a number of distinct sediment samples to the organic carbon content of the samples, the QSARs were made operative for predicting rates of reduction of given halocarbons in given sediment-water systems. The correlations were enhanced by taking into account the fraction of the compounds sorbed to the solid phase. (Copyright (c) 1991 Elsevier Science Publishers B.V.)

  10. Reactivity and fate of secondary alkane sulfonates (SAS) in marine sediments.

    PubMed

    Baena-Nogueras, Rosa María; Rojas-Ojeda, Patricia; Sanz, José Luis; González-Mazo, Eduardo; Lara-Martín, Pablo A

    2014-06-01

    This research is focused on secondary alkane sulfonates (SAS), anionic surfactants widely used in household applications that access aquatic environments mainly via sewage discharges. We studied their sorption capacity and anaerobic degradation in marine sediments, providing the first data available on this topic. SAS partition coefficients increased towards those homologues having longer alkyl chains (from up to 141 L kg(-1) for C14 to up to 1753 L kg(-1) for C17), which were those less susceptible to undergo biodegradation. Overall, SAS removal percentages reached up to 98% after 166 days of incubation using anoxic sediments. The degradation pathway consisted on the formation of sulfocarboxylic acids after an initial fumarate attack of the alkyl chain and successive β-oxidations. This is the first study showing that SAS can be degraded in absence of oxygen, so this new information should be taken into account for future environmental risk assessments on these chemicals.

  11. Microeukaryotic diversity in marine environments, an analysis of surface layer sediments from the East Sea.

    PubMed

    Park, Soo-Je; Park, Byoung-Joon; Pham, Vinh Hoa; Yoon, Dae-No; Kim, Si-Kwan; Rhee, Sung-Keun

    2008-06-01

    Molecular techniques, based on clone library of 18S rRNA gene, were employed to ascertain the diversity of microeukaryotic organisms in sediments from the East Sea. A total of 261 clones were recovered from surface sediments. Most of the clone sequences (90%) were affiliated with protists, dominated by Ciliates (18%) and Dinoflagellates (19%) of Alveolates, phototrophic Stramenopiles (11%), and Cercozoa (20%). Many of the clones were related to uncultivated eukaryotes clones retrieved from anoxic environments with several highly divergent 18S rRNA gene sequences. However, no clones were related to cultivated obligate anaerobic protists. Protistan communities between subsurface layers of 1 and 9 cm shared 23% of total phylotypes which comprised 64% of total clones retrieved. Analysis of diversity indices and rarefaction curve showed that the protistan community within the 1 cm layer exhibited higher diversity than the 9 cm layer. Our results imply that diverse protists remain to be uncovered within marine benthic environments.

  12. Reactivity and fate of secondary alkane sulfonates (SAS) in marine sediments.

    PubMed

    Baena-Nogueras, Rosa María; Rojas-Ojeda, Patricia; Sanz, José Luis; González-Mazo, Eduardo; Lara-Martín, Pablo A

    2014-06-01

    This research is focused on secondary alkane sulfonates (SAS), anionic surfactants widely used in household applications that access aquatic environments mainly via sewage discharges. We studied their sorption capacity and anaerobic degradation in marine sediments, providing the first data available on this topic. SAS partition coefficients increased towards those homologues having longer alkyl chains (from up to 141 L kg(-1) for C14 to up to 1753 L kg(-1) for C17), which were those less susceptible to undergo biodegradation. Overall, SAS removal percentages reached up to 98% after 166 days of incubation using anoxic sediments. The degradation pathway consisted on the formation of sulfocarboxylic acids after an initial fumarate attack of the alkyl chain and successive β-oxidations. This is the first study showing that SAS can be degraded in absence of oxygen, so this new information should be taken into account for future environmental risk assessments on these chemicals. PMID:24631971

  13. PRELIMINARY RESULTS: RELEASE OF METALS FROM ACID-MINE DRAINAGE CONTAMINATED STREAMBED SEDIMENTS UNDER ANOXIC CONDITIONS

    EPA Science Inventory

    Many miles of streams are contaminated with acid-mine drainage (AMD) from abandoned metal mines in the western U.S. Treatment of these streams may include dredging of the existing sediments, with subsequent burial. Burial of previously toxic sediments may result in release of met...

  14. Trace element abundances in the Rock Canyon Anticline, Pueblo, Colorado, marine sedimentary section and their relationship to Caribbean plateau construction and oxygen anoxic event 2

    NASA Astrophysics Data System (ADS)

    Snow, Laura J.; Duncan, Robert A.; Bralower, Timothy J.

    2005-09-01

    Rapid eruption of submarine lava flows during formation of the Caribbean plateau correlates closely with ocean anoxic event 2 (OAE2), which bracketed the Cenomanian/Turonian boundary (˜93.5 Ma). These events also correspond with a positive excursion in carbon isotopic composition of seawater. Hydrothermal activity associated with large-scale submarine volcanism may have been responsible for this abrupt change in ocean chemistry. We determined the distribution of major, minor, and trace element abundances in the Rock Canyon marine sedimentary section (Pueblo, Colorado). After normalizing element concentrations to Zr to remove the variable contribution of terrigenous material to these sediments, we detected an interval of concentrated metal abundance anomalies that coincides with the abrupt beginning of the positive δ13C isotope excursion. The metal abundance anomalies indicate that intermittent hydrothermal activity, in the form of both water/rock exchange and magmatic degassing, introduced large concentrations of trace metals into the Cretaceous ocean at the same time that extinctions of benthic species, turnover in plankton communities, and increases in isotopically light organic carbon burial occurred. The stratigraphic position of this interval of trace metal anomalies matches events associated with OAE2 and indicates that intermittent hydrothermal activity on a massive scale triggered abrupt changes in carbon burial and deep ocean oxygen contents.

  15. Platinum-group elements (PGE) and Rhenium in Marine Sediments across the Cretaceous-Tertiary Boundary: Constraints on Re-PGE Transport in the Marine Environment

    NASA Technical Reports Server (NTRS)

    Lee, Cin-Ty Aeolus; Wasserburg, Gerald J.; Kyte, Frank T.

    2003-01-01

    environment is a general process throughout geologic time because most of the inputs of Os and Ir into the ocean have OsAr ratios greater than or = 1. Mass balance calculations show that Os and Re burial fluxes in pelagic sediments account for only a small fraction of the riverine Os (less than 10%) and Re (less than 0.1%) inputs into the oceans. In contrast, burial of Ir in pelagic sediments is similar to the riverine Ir input, indicating that pelagic sediments are a much larger repository for Ir than for Os and Re. If all of the missing Os and Re is assumed to reside in anoxic sediments in oceanic margins, the calculated burial fluxes in anoxic sediments are similar to observed burial fluxes. However, putting all of the missing Os and Re into estuarine sediments would require high concentrations to balance the riverine input and would also fail to explain the depletion of Os at pelagic KTB sites, where at most approx. 25% of the K-T impactor's Os could have passed through estuaries. If Os is preferentially sequestered in anoxic marine environments, it follows that the OsAr ratio of pelagic sediments should be sensitive to changes in the rates of anoxic sediment deposition. There is thus a clear fractionation of Os and Re from Ir in precipitation out of sea water in pelagic sections. Accordingly, it is inferred here that Re and Os are removed from sea water in anoxic marine depositional regimes.

  16. Microbial colonization and degradation of polyethylene and biodegradable plastic bags in temperate fine-grained organic-rich marine sediments.

    PubMed

    Nauendorf, Alice; Krause, Stefan; Bigalke, Nikolaus K; Gorb, Elena V; Gorb, Stanislav N; Haeckel, Matthias; Wahl, Martin; Treude, Tina

    2016-02-15

    To date, the longevity of plastic litter at the sea floor is poorly constrained. The present study compares colonization and biodegradation of plastic bags by aerobic and anaerobic benthic microbes in temperate fine-grained organic-rich marine sediments. Samples of polyethylene and biodegradable plastic carrier bags were incubated in natural oxic and anoxic sediments from Eckernförde Bay (Western Baltic Sea) for 98 days. Analyses included (1) microbial colonization rates on the bags, (2) examination of the surface structure, wettability, and chemistry, and (3) mass loss of the samples during incubation. On average, biodegradable plastic bags were colonized five times higher by aerobic and eight times higher by anaerobic microbes than polyethylene bags. Both types of bags showed no sign of biodegradation during this study. Therefore, marine sediment in temperate coastal zones may represent a long-term sink for plastic litter and also supposedly compostable material. PMID:26790603

  17. Microbial colonization and degradation of polyethylene and biodegradable plastic bags in temperate fine-grained organic-rich marine sediments.

    PubMed

    Nauendorf, Alice; Krause, Stefan; Bigalke, Nikolaus K; Gorb, Elena V; Gorb, Stanislav N; Haeckel, Matthias; Wahl, Martin; Treude, Tina

    2016-02-15

    To date, the longevity of plastic litter at the sea floor is poorly constrained. The present study compares colonization and biodegradation of plastic bags by aerobic and anaerobic benthic microbes in temperate fine-grained organic-rich marine sediments. Samples of polyethylene and biodegradable plastic carrier bags were incubated in natural oxic and anoxic sediments from Eckernförde Bay (Western Baltic Sea) for 98 days. Analyses included (1) microbial colonization rates on the bags, (2) examination of the surface structure, wettability, and chemistry, and (3) mass loss of the samples during incubation. On average, biodegradable plastic bags were colonized five times higher by aerobic and eight times higher by anaerobic microbes than polyethylene bags. Both types of bags showed no sign of biodegradation during this study. Therefore, marine sediment in temperate coastal zones may represent a long-term sink for plastic litter and also supposedly compostable material.

  18. Dynamics of Nitrification and Denitrification in Root-Oxygenated Sediments and Adaptation of Ammonia-Oxidizing Bacteria to Low-Oxygen or Anoxic Habitats

    PubMed Central

    Bodelier, P.; Libochant, J. A.; Blom, C.; Laanbroek, H. J.

    1996-01-01

    Oxygen-releasing plants may provide aerobic niches in anoxic sediments and soils for ammonia-oxidizing bacteria. The oxygen-releasing, aerenchymatous emergent macrophyte Glyceria maxima had a strong positive effect on numbers and activities of the nitrifying bacteria in its root zone in spring and early summer. The stimulation of the aerobic nitrifying bacteria in the freshwater sediment, ascribed to oxygen release by the roots of G. maxima, disappeared in late summer. Numbers and activities of the nitrifying bacteria were positively correlated, and a positive relationship with denitrification activities also was found. To assess possible adaptations of ammonia-oxidizing bacteria to low-oxygen or anoxic habitats, a comparison was made between the freshwater lake sediment and three soils differing in oxicity profiles. Oxygen kinetics and tolerance to anoxia of the ammonia-oxidizing communities from these habitats were determined. The apparent K(infm) values for oxygen of the ammonia-oxidizing community in the lake sediment were in the range of 5 to 15 (mu)M, which was substantially lower than the range of K(infm) values for oxygen of the ammonia-oxidizing community from a permanently oxic dune location. Upon anoxic incubation, the ammonia-oxidizing communities of dune, chalk grassland, and calcareous grassland soils lost 99, 95, and 92% of their initial nitrifying capacity, respectively. In contrast, the ammonia-oxidizing community in the lake sediment started to nitrify within 1 h upon exposure to oxygen at the level of the initial capacity. It is argued that the conservation of the nitrifying capacity during anoxic periods and the ability to react instantaneously to the presence of oxygen are important traits of nitrifiers in fluctuating oxic-anoxic environments such as the root zone of aerenchymatous plant species. PMID:16535441

  19. ENANTIOSELECTIVE TRANSFORMATION OF CHIRAL PCBS AND THE INSECTICIDE FIPRONIL IN NATURAL ANOXIC SEDIMENTS

    EPA Science Inventory

    In this study, we examined the microbial transformation of two chiral PCB congeners and the insecticide fipronil in natural sediment microcosms. The specific goals of the study were to identify biotransformation pathways and determine if enantioselective microbial transformation ...

  20. Desulfuromonas thiophila sp. nov., a new obligately sulfur-reducing bacterium from anoxic freshwater sediment

    USGS Publications Warehouse

    Finster, K.; Coates, J.D.; Liesack, W.; Pfennig, N.

    1997-01-01

    A mesophilic, acetate-oxidizing, sulfur-reducing bacterium, strain NZ27(T), was isolated from anoxic mud from a freshwater sulfur spring. The cells were ovoid, motile, and gram negative. In addition to acetate, the strain oxidized pyruvate, succinate, and fumarate. Sulfur flower could be replaced by polysulfide as an electron acceptor. Ferric nitrilotriacetic acid was reduced in the presence of pyruvate; however, this reduction did not sustain growth. These phenotypic characteristics suggested that strain NZ27(T) is affiliated with the genus Desulfuromonas. A phylogenetic analysis based on the results of comparative 16S ribosomal DNA sequencing confirmed that strain NZ27(T) belongs to the Desulfuromonas cluster in the recently proposed family 'Geobacteraceae' in the delta subgroup of the Proteobacteria. In addition, the results of DNA-DNA hybridization studies confirmed that strain NZ27(T) represents a novel species. Desulfuromonas thiophila, a name tentatively used in previous publications, is the name proposed for strain NZ27(T) in this paper.

  1. Alkyl amides in two organic-rich anoxic sediments: A possible new abiotic route for N sequestration

    NASA Astrophysics Data System (ADS)

    McKee, Georgina A.; Hatcher, Patrick G.

    2010-11-01

    Fixed nitrogen (N) plays an integral role in global cycling; while most is recycled to refuel primary productivity, a small fraction escapes to be preserved and stabilised in sediments. Despite decades of research, the functionality and reactivity of this sequestered organic N has been poorly understood. This study was undertaken to shed light on this problem by characterising the bulk sediment organic matter using nuclear magnetic resonance (NMR), followed by molecular level analysis using ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). We studied two organic-rich anaerobic sediments, one from a freshwater system and another from a marine paralic basin. Mangrove Lake, Bermuda (marine) and Mud Lake, Florida (freshwater) have been shown in past studies to contain high levels of N-containing organic matter. Our resulting multidimensional NMR data suggests the existence of a new type of amide functionality in both these lake sediments, and we investigated this further using FT-ICR-MS and gas chromatography mass spectrometry (GC-MS). FT-ICR-MS confirmed the existence of homologous series of CHNO containing compounds, whose structures are verified using GC-MS as alkyl amides. Model reactions involving naturally occurring esters and ammonia suggest the source of alkyl amides to be amidation of esters with sedimentary ammonia derived from anaerobic degradation of organic matter. This expands upon previous hypotheses for preservation of amide containing compounds that call upon biological/abiological protection of proteins and peptides or the formation of refractory nitrogenous adducts.

  2. Metaproteomic analysis of bacterial communities in marine mudflat aquaculture sediment.

    PubMed

    Lin, Rui; Lin, Xiangmin; Guo, Tingting; Wu, Linkun; Zhang, Wenjing; Lin, Wenxiong

    2015-09-01

    Bacteria living in marine sediment play crucial roles in the benthic-pelagic interface coupling process. However, the complexity of the marine environment and the abundance of interfering materials hamper metaproteomic research of the marine mudflat environment. In this study, a modified sequential protein extraction method was used for marine mudflat sediment metaproteomic investigation. For marine sediment samples in cultured clam mudflat, more than 1000 protein spots were visualized in a two-dimensional gel electrophoresis map and 78 % of 194 randomly selected spots were successfully identified by mass spectrometry. We further applied this method to compare long-term clam aquaculture and natural mudflat sediment and identified 53 altered proteins from different microbe resources, which belonged to different functional categories or metabolic pathways. We found that proteins involved in stress/defense response process, ATP regeneration and protein folding more inclined to increase abundance while arginine biosynthesis and signal transduction process related proteins preferred to decrease in clam cultured mudflat sediment. Meanwhile, proteins were abundant in pathogens of bivalves, such as Vibrio and Photobacterium, and decreased in Acinetobacter, after about 8 months clam cultured. Furthermore, the terminal restriction fragment length polymorphism assay was performed to compare microbial community composition between sediments mentioned above. Results showed that the top three enrich genera in natural sediment were Cytophaga, Butyrivibrio and Spirochaeta, while Cytophaga, Spirochaeta and Azoarcus were found enrichment in long-term mudflat aquaculture sediment.

  3. Anaerobic versus aerobic degradation of dimethyl sulfide and methanethiol in anoxic freshwater sediments

    SciTech Connect

    Lomans, B.P.; Op den Camp, H.J.M.; Pol, A.; Vogels, G.D.

    1999-02-01

    Degradation of dimethyl sulfide and methanethiol in slurries prepared from sediments of minerotrophic peatland ditches were studied under various conditions. Maximal aerobic dimethyl sulfide-degrading capacities, measured in bottles shaken under an air atmosphere, were 10-fold higher than the maximal anaerobic degrading capacities determined from bottles shaken under N{sub 2} or H{sub 2} atmosphere. Incubations under experimental conditions which mimic the in situ conditions, however, revealed that aerobic degradation of dimethyl sulfide and methanethiol in freshwater sediments is low due to oxygen limitation. Inhibition studies with bromoethanesulfonic acid and sodium tungstate demonstrated that the degradation of dimethyl sulfide and methanethiol in these incubations originated mainly from methanogenic activity. Prolonged incubation under a H{sub 2} atmosphere resulted in lower dimethyl sulfide degradation rates. Kinetic analysis of the data resulted in apparent K{sub m} values (6 to 8 {micro}M) for aerobic dimethyl sulfide degradation which are comparable to those reported for Thiobacillus spp., Hyphomicrobium spp., and other methylotrophs. Apparent K{sub m} values determined for anaerobic degradation of dimethyl sulfide were of the same order of magnitude. The low apparent K{sub m} values obtained explain the low dimethyl sulfide and methanethiol concentrations in freshwater sediments that they reported previously. The observations point to methanogenesis as the major mechanism of dimethyl sulfide and methanethiol consumption in freshwater sediments.

  4. ON THE USE OF HYDROCHLORIC ACID FOR DETERMINING SOLID-PHASE ARSENIC PARTITIONING IN ANOXIC SEDIMENTS

    EPA Science Inventory

    One of the challenges in assessing the current impact of the discharge of arsenic contaminated ground water into a surface water body is differentiating the arsenic ground water flux versus dissolution of in-place contaminated sediments. Results from a field study at a Superfund...

  5. PCB contamination in marine sediments from Golfo Dulce, Pacific coast of Costa Rica.

    PubMed

    Spongberg, Alison L

    2004-12-01

    Twenty-nine marine sediment samples collected from 1996 through 2002 from the Golfo Dulce embayment of Costa Rica were analyzed for PCB concentrations. The Esquinas River and Rincon Bay in the northern and western part of the gulf had relatively low overall concentrations of PCBs, with no samples having greater than 2.1 microg/g dw sediment. The Port of Golfito had the highest overall concentrations, ranging up to 15.7 microg/g dw sediment. These samples were also dominated by higher chlorinated congeners. Samples from the deeper (> 100 m) waters in the northern part of the gulf, as well as within the sediment plume from the Rio Coto Colorado had intermediate values. Within the Rio Coto Colorado sediment plume the concentrations did decrease with increasing depth and the congeners showed a shift towards less chlorinated congeners with depth. However, the deep northern basin had some of the highest PCB concentrations and the shift towards less chlorinated congeners was not apparent or significant. Whether the anoxic conditions that exist in the deep waters are capable of initiating dechlorination is still unknown. Overall, the data from Golfo Dulce show moderate PCB contamination, despite the pristine nature of the gulf and surrounding lands.

  6. Bioremediation of oil polluted marine sediments: A bio-engineering treatment.

    PubMed

    Cappello, Simone; Calogero, Rosario; Santisi, Santina; Genovese, Maria; Denaro, Renata; Genovese, Lucrezia; Giuliano, Laura; Mancini, Giuseppe; Yakimov, Michail M

    2015-06-01

    The fate of hydrocarbon pollutants and the development of oil-degrading indigenous marine bacteria in contaminated sediments are strongly influenced by abiotic factors such as temperature, low oxygen levels, and nutrient availability. In this work, the effects of different biodegradation processes (bioremediation) on oil-polluted anoxic sediments were analyzed. In particular, as a potential bioremediation strategy for polluted sediments, we applied a prototype of the "Modular Slurry System" (MSS), allowing containment of the sediments and their physical-chemical treatment (by air insufflations, temperature regulation, and the use of a slow-release fertilizer). Untreated polluted sediments served as the blank in a non-controlled experiment. During the experimental period (30 days), bacterial density and biochemical oxygen demand were measured and functional genes were identified by screening. Quantitative measurements of pollutants and an eco-toxicological analysis (mortality of Corophium orientale) were carried out at the beginning and end of the experiments. The results demonstrated the high biodegradative capability achieved with the proposed technology and its strong reduction of pollutant concentrations and thus toxicity. PMID:26496620

  7. Bioremediation of oil polluted marine sediments: A bio-engineering treatment.

    PubMed

    Cappello, Simone; Calogero, Rosario; Santisi, Santina; Genovese, Maria; Denaro, Renata; Genovese, Lucrezia; Giuliano, Laura; Mancini, Giuseppe; Yakimov, Michail M

    2015-06-01

    The fate of hydrocarbon pollutants and the development of oil-degrading indigenous marine bacteria in contaminated sediments are strongly influenced by abiotic factors such as temperature, low oxygen levels, and nutrient availability. In this work, the effects of different biodegradation processes (bioremediation) on oil-polluted anoxic sediments were analyzed. In particular, as a potential bioremediation strategy for polluted sediments, we applied a prototype of the "Modular Slurry System" (MSS), allowing containment of the sediments and their physical-chemical treatment (by air insufflations, temperature regulation, and the use of a slow-release fertilizer). Untreated polluted sediments served as the blank in a non-controlled experiment. During the experimental period (30 days), bacterial density and biochemical oxygen demand were measured and functional genes were identified by screening. Quantitative measurements of pollutants and an eco-toxicological analysis (mortality of Corophium orientale) were carried out at the beginning and end of the experiments. The results demonstrated the high biodegradative capability achieved with the proposed technology and its strong reduction of pollutant concentrations and thus toxicity.

  8. Genetic Diversity of Microbial Eukaryotes in Anoxic Sediment of the Saline Meromictic Lake Namako-ike (Japan): On the Detection of Anaerobic or Anoxic-tolerant Lineages of Eukaryotes.

    PubMed

    Takishita, Kiyotaka; Tsuchiya, Masashi; Kawato, Masaru; Oguri, Kazumasa; Kitazato, Hiroshi; Maruyama, Tadashi

    2007-01-01

    Available sequence data on eukaryotic small-subunit ribosomal DNA (SSU rDNA) directly retrieved from various environments have increased recently, and the diversity of microbial eukaryotes (protists) has been shown to be much greater than previously expected. However, the molecular information accumulated to date does still not thoroughly reveal ecological distribution patterns of microbial eukaryotes. In the ongoing challenge to detect anaerobic or anoxic-tolerant lineages of eukaryotes, we directly extracted DNA from the anoxic sediment of a saline meromictic lake, constructed genetic libraries of PCR-amplified SSU rDNA, and performed phylogenetic analyses with the cloned SSU rDNA sequences. Although a few sequences could not be confidently assigned to any major eukaryotic groups in the analyses and are debatable regarding their taxonomic positions, most sequences obtained have affiliations with known major lineages of eukaryotes (Cercozoa, Alveolata, Stramenopiles, and Opisthokonta). Among these sequences, some branched with lineages predominantly composed of uncultured environmental clones retrieved from other anoxic environments, while others were closely related to those of eukaryotic parasites (e.g. Phytomyxea of Cercozoa, Gregarinea of Alveolata, and Ichthyosporea of Opisthokonta).

  9. PAH dissipation in a contaminated river sediment under oxic and anoxic conditions.

    PubMed

    Quantin, C; Joner, E J; Portal, J M; Berthelin, J

    2005-03-01

    A batch experiment was conducted to compare PAH degradation in a polluted river sediment under aerobic and anaerobic conditions, and to investigate whether input of fresh organic material (cellulose) could enhance such degradation. All measurements were checked against abiotic control treatments to exclude artifacts of sample preparation and non-biological processes like aging. Three- and four-ring PAHs could be degraded by the indigenous microbial community under aerobic conditions, but anaerobic metabolism based on iron and sulphate reduction was not coupled with PAH degradation of even the simplest 3-ring compounds like phenanthrene. Cellulose addition stimulated both aerobic and anaerobic respiration, but had no effect on PAH dissipation. We conclude that natural attenuation of PAHs in polluted river sediments under anaerobic conditions is exceedingly slow. Dredging and biodegradation on land under aerobic conditions would be required to safely remediate and restore polluted sites. PMID:15589658

  10. Sediment Core Sectioning and Extraction of Pore Waters under Anoxic Conditions.

    PubMed

    Keimowitz, Alison R; Zheng, Yan; Lee, Ming-Kuo; Natter, Michael; Keevan, Jeffrey

    2016-01-01

    We demonstrate a method for sectioning sediment cores and extracting pore waters while maintaining oxygen-free conditions. A simple, inexpensive system is built and can be transported to a temporary work space close to field sampling site(s) to facilitate rapid analysis. Cores are extruded into a portable glove bag, where they are sectioned and each 1-3 cm thick section (depending on core diameter) is sealed into 50 ml centrifuge tubes. Pore waters are separated with centrifugation outside of the glove bag and then returned to the glove bag for separation from the sediment. These extracted pore water samples can be analyzed immediately. Immediate analyses of redox sensitive species, such as sulfide, iron speciation, and arsenic speciation indicate that oxidation of pore waters is minimal; some samples show approximately 100% of the reduced species, e.g. 100% Fe(II) with no detectable Fe(III). Both sediment and pore water samples can be preserved to maintain chemical species for further analysis upon return to the laboratory. PMID:27023267

  11. Ubiquitous Presence and Novel Diversity of Anaerobic Alkane Degraders in Cold Marine Sediments

    PubMed Central

    Gittel, Antje; Donhauser, Johanna; Røy, Hans; Girguis, Peter R.; Jørgensen, Bo B.; Kjeldsen, Kasper U.

    2015-01-01

    Alkanes are major constituents of crude oil and are released to the marine environment by natural seepage and from anthropogenic sources. Due to their chemical inertness, their removal from anoxic marine sediments is primarily controlled by the activity of anaerobic alkane-degrading microorganisms. To facilitate comprehensive cultivation-independent surveys of the diversity and distribution of anaerobic alkane degraders, we designed novel PCR primers that cover all known diversity of the 1-methylalkyl succinate synthase gene (masD/assA), which catalyzes the initial activation of alkanes. We studied masD/assA gene diversity in pristine and seepage-impacted Danish coastal sediments, as well as in sediments and alkane-degrading enrichment cultures from the Middle Valley (MV) hydrothermal vent system in the Pacific Northwest. MasD/assA genes were ubiquitously present, and the primers captured the diversity of both known and previously undiscovered masD/assA gene diversity. Seepage sediments were dominated by a single masD/assA gene cluster, which is presumably indicative of a substrate-adapted community, while pristine sediments harbored a diverse range of masD/assA phylotypes including those present in seepage sediments. This rare biosphere of anaerobic alkane degraders will likely increase in abundance in the event of seepage or accidental oil spillage. Nanomolar concentrations of short-chain alkanes (SCA) were detected in pristine and seepage sediments. Interestingly, anaerobic alkane degraders closely related to strain BuS5, the only SCA degrader in pure culture, were found in mesophilic MV enrichments, but not in cold sediments from Danish waters. We propose that the new masD/assA gene lineages in these sediments represent novel phylotypes that are either fueled by naturally occurring low levels of SCA or that metabolize medium- to long-chain alkanes. Our study highlights that masD/assA genes are a relevant diagnostic marker to identify seepage and microseepage, e

  12. Ubiquitous Presence and Novel Diversity of Anaerobic Alkane Degraders in Cold Marine Sediments.

    PubMed

    Gittel, Antje; Donhauser, Johanna; Røy, Hans; Girguis, Peter R; Jørgensen, Bo B; Kjeldsen, Kasper U

    2015-01-01

    Alkanes are major constituents of crude oil and are released to the marine environment by natural seepage and from anthropogenic sources. Due to their chemical inertness, their removal from anoxic marine sediments is primarily controlled by the activity of anaerobic alkane-degrading microorganisms. To facilitate comprehensive cultivation-independent surveys of the diversity and distribution of anaerobic alkane degraders, we designed novel PCR primers that cover all known diversity of the 1-methylalkyl succinate synthase gene (masD/assA), which catalyzes the initial activation of alkanes. We studied masD/assA gene diversity in pristine and seepage-impacted Danish coastal sediments, as well as in sediments and alkane-degrading enrichment cultures from the Middle Valley (MV) hydrothermal vent system in the Pacific Northwest. MasD/assA genes were ubiquitously present, and the primers captured the diversity of both known and previously undiscovered masD/assA gene diversity. Seepage sediments were dominated by a single masD/assA gene cluster, which is presumably indicative of a substrate-adapted community, while pristine sediments harbored a diverse range of masD/assA phylotypes including those present in seepage sediments. This rare biosphere of anaerobic alkane degraders will likely increase in abundance in the event of seepage or accidental oil spillage. Nanomolar concentrations of short-chain alkanes (SCA) were detected in pristine and seepage sediments. Interestingly, anaerobic alkane degraders closely related to strain BuS5, the only SCA degrader in pure culture, were found in mesophilic MV enrichments, but not in cold sediments from Danish waters. We propose that the new masD/assA gene lineages in these sediments represent novel phylotypes that are either fueled by naturally occurring low levels of SCA or that metabolize medium- to long-chain alkanes. Our study highlights that masD/assA genes are a relevant diagnostic marker to identify seepage and microseepage, e

  13. Influence of chemical reactivities of lipids bound in different pools on their isotopic compositions during degradation in marine sediments

    NASA Astrophysics Data System (ADS)

    Sun, M.; Pan, H.; Culp, R.

    2013-05-01

    Lipid biomarkers and associated compound specific stable carbon isotope compositions have been widely applied to study biogeochemical cycling of organic matter in natural environments. This experimental study was specifically designed to examine the influence of chemical reactivities of lipid compounds bound in different pools on their isotopic composition during microbial degradation in marine sediments. 13C-labeled (labeling at different carbon positions of fatty acid chains) and unlabeled tripalmitins were spiked and incubated in natural oxic (top 1 cm) and anoxic (> 10 cm) marine sediments. In anoxic sediments, neither naturally-occurred fatty acids nor tripalmitin-derived 16:0 fatty acid were apparently degraded within two months and hence no significant variation in stable carbon isotopic composition of 16:0 fatty acid was observed. However, in oxic sediments, both naturally-occurred fatty acids and spiked tripalmitin-derived 16:0 fatty acid were degraded by 26% - 95% during incubation. For natural fatty acids such as 14:0, 16:1, 18:1, 20:5/20:4, and >C20:0, degradation rates varied according to the following order: polyunsaturated > monounsaturated > short chain saturated > long chain saturated fatty acids, which reflects variable reactivities of natural lipid compounds from different sources. Tripalmitin-derived 16:0 fatty acid degraded at an at least 2-3× faster rate compared to naturally-occurred 16:0 in sediments. Meanwhile, isotopic compositions of 16:0 fatty acid in the oxic sediments shifted negatively during incubation. It appears that the isotopic shifts are dependent on the amount of 13C-labeled compound spiked into the sediments but not related to the labeling position of 13C in the molecular structure. The results from this study provide direct evidence that the relative reactivities of lipid compounds from different sources (or different pools) can cause alterations in molecular isotopic composition during microbial degradation in natural

  14. Phosphorus regeneration and burial in near-shore marine sediments (the Gulf of Trieste, northern Adriatic Sea)

    NASA Astrophysics Data System (ADS)

    Ogrinc, N.; Faganeli, J.

    2006-05-01

    According to bioassay studies and high dissolved nutrient N/P ratios in the seawater column, phosphorus (P) is thought to control marine productivity in the northern Adriatic Sea. P in near-shore marine sediments of the Gulf of Trieste, the northernmost part of the Adriatic Sea, was investigated using pore water P distributions, and benthic P flux studies under oxic and anoxic conditions. The data show that P regeneration is up to three-fold more extensive in sediments overlain by oxygen-depleted waters and proceeds in parallel with Fe and Mn enhanced benthic fluxes. It appears from the incubation experiments that degradation of sedimentary organic matter is the main contribution to the flux of P at the sediment-water interface, while the release of phosphate adsorbed on the iron oxide surface is of minor importance. It appears that about 50% of P in the Gulf of Trieste is retained within in the sediments, probably bonded to clay minerals and carbonate grains or precipitated as fluoroapatite. In these sediments total P (P tot) is preserved preferentially over organic C (C org). P regenerated from surficial sediments contributes about 1/3 of the P that is assimilated by benthic microalgae. The phytoplankton P requirement should be entirely supplied from fresh-water sources. These results suggest that oxygen depletion in coastal areas caused by eutrophication enhances P regeneration from sediments, providing the additional P necessary for increased biological productivity. The development of anoxic bottom waters in coastal areas enhances the recycling of P, exacerbating the nutrient requirement in the area. A geochemical record of P burial in a longer sedimentary sequence revealed an increasing trend of P tot and organic P (P org) contents occurring approximately 50 years BP (after 1950), probably due to increasing use of inorganic fertilizers and detergents in the area.

  15. Identification of a granulin-like transcript expressed during anoxic exposure and translated during aerobic recovery in a marine gastropod.

    PubMed

    Larade, Kevin; Storey, Kenneth B

    2008-02-29

    A novel transcript encoding a cysteine-rich granulin-like peptide (l-grn) was identified in the hepatopancreas of the marine intertidal gastropod, Littorina littorea, an anoxia-tolerant species. Experimental exposure of snails to anoxia induced a gradual accumulation of l-grn transcripts over time, with expression regulated in vitro through elements responsive to second messengers of protein kinases A, C and G. Translation of this transcript was analyzed by examining l-grn association with ribosomes during normoxia, anoxia, and aerobic recovery. Transcripts of l-grn were associated with polysomes during normoxia, moved into the monosome fractions under anoxia, but shifted back to the polysomal fractions during aerobic recovery. Western blotting confirmed this with a granulin-like protein detected under normoxic conditions, but not during anoxia exposure. A significant increase in the precursor protein and peptide (L-GRN) was observed during the aerobic recovery period. The accumulation of l-grn transcripts during anoxic exposure and subsequent translation following the return to aerobic conditions may be a response to oxidant damage that occurs during re-oxygenation. Overall, the data show that the l-grn gene is anoxia-responsive in this species and may have pro-survival functions during the recovery period. PMID:18187271

  16. DNA damage in the gill cells of the marine scallop Mizuhopecten yessoensis during anoxic stress and aerobic recovery

    NASA Astrophysics Data System (ADS)

    Slobodskova, Valentina V.; Zhukovskaya, Avianna F.; Chelomin, Victor P.

    2012-06-01

    Anoxia-induced DNA damage in the gill cells of the marine scallop Mizuhopecten yessoensis was assessed with the alkaline comet assay (single-cell gel electrophoresis). The alkaline comet assay method for detecting DNA strand breaks and alkali labile sites in individual cells. DNA damage was determened in the scallops ( M. yessoensis) gill cells. The scallops were exposed to air for 8 h showing a clear increase in the levels of DNA damage. After the air exposure, M. yessoensis were re-submersed for a period of 12 h, leading values to return to a pre-aerial exposure level. Control animals were kept immersed during the whole period. The resulting data demonstrate that natural influences, such as oxygen depletion (anoxia) in seawater, can be responsible for the induction of DNA damage. If the scallops were re-immersed in oxic conditions, the anoxically induced breaks were repaired. The main mechanisms influencing the integrity of the DNA structure are discussed in this paper.

  17. Dissolution and analysis of amorphous silica in marine sediments.

    USGS Publications Warehouse

    Eggimann, D.W.; Manheim, F. T.; Betzer, P.R.

    1980-01-01

    The analytical estimation of amorphous silica in selected Atlantic and Antarctic Ocean sediments, the U.S.G.S. standard marine mud (MAG-1), A.A.P.G. clays, and samples from cultures of a marine diatom, Hemidiscus, has been examined. Our values for amorphous silica-rich circum-Antarctic sediments are equal to or greater than literature values, whereas our values for a set of amorphous silica-poor sediments from a transect of the N. Atlantic at 11oN, after appropriate correction for silica released from clays, are significantly lower than previous estimates from the same region. -from Authors

  18. Bioavailability of sediment-bound contaminants to marine organisms

    SciTech Connect

    Brown, B. |

    1993-09-01

    The bioavailability of sediment-bound contaminants to marine organisms indicates that there exists a potential for transfer of these contaminants through marine food webs to commercial fisheries products consumed by humans. However, there has been relatively little effort to combine and synthesize data on chemical/biological interactions between benthic animals and seagrasses and the sediments in which they reside on the one hand, and on the chemistry of bioaccumulation on the other. This report provides a conceptual basis for an approach to bioavailability and biomagnification of sediment-bound contaminants that reviews biological and chemical approaches.

  19. Is these a link between eustatic variations, platform drowning, oceanic anoxic events, and ammonite faunal turnovers ? Case study of the Aptian sediments along the northern Tethyan margin

    NASA Astrophysics Data System (ADS)

    Pictet, Antoine; Föllmi, Karl; Spangenberg, Jorge

    2014-05-01

    The early Aptian witnessed an important episode of paleoenvironmental change, which has been linked to major marine volcanic activity related to the formation of the Ontong-Java large igneous province (e.g., Larson and Erba, 1999). This phase culminated in the formation of hemipelagic and pelagic organic-rich sediments, whereas profound changes are also observed in shallow-water settings, with the step-by-step disappearance of the northern Tethyan platform. Results show that the northern Tethyan platform has passed through three major crises in its evolution during the early Aptian. A first one started with an emersion phase, marked by a subaerial karstified discontinuity reported from the middle early Aptian (Deshayesites forbesi or early D. deshayesi zone). This is directly followed by the drowning of the Urgonian platform along the northern Tethyan margin, preceding the Selli Episode. The period following this drowning phase coincides with the negative and the following positive excursions in the δ13C records and went along with the deposition of the so-called Lower Grünten Member, which is the result of heterozoan carbonate production and characterized by increased detrital input. Ammonite fauna witnessed an important diversification of hemipelagic forms, especially inside the heteromorph Ancyloceratacea. This radiation is probably linked to the expansion of hemipelagic facies, one of the main habitats of ammonites. A second phase, reported from the late early Aptian (late D. deshayesi zone), started with a small drowning event, marked by a firmground and by a phosphatic enrichment. This stratigraphical layer also corresponds to the establishment of the anoxic Apparein level. Above, the Upper Grünten Member continues with heterozoan carbonate production or with glauconitic condensed sediments. The corresponding δ13C record is a the onset of a long-term decrease. The ammonite fauna is marked by a first turnover with the disappearance of Deshayesites, and the

  20. Carotenoid diagenesis in recent marine sediments: II. Degradation of fucoxanthin to loliolide

    NASA Astrophysics Data System (ADS)

    Repeta, Daniel J.

    1989-03-01

    The quantitative distributions of loliolide and the major phytoplankton carotenoids: fucoxanthin, diadinochrome, diatoxanthin, and β-carotene in two cores of anoxic marine sediment recovered from the Peru continental shelf are reported. Our results demonstrate that the rapid degradation of carotenoids in sediments is not a result of their high degree of unsaturation as has been previously suggested. Instead, carotenoids exhibit a wide range of degradation rates that are proportional to the ability of specific pigments to form unstable bicyclic furanoxides. Carotenoid furanoxides undergo subsequent fragmentation to loliolide, isololiolide, dihydroactinidiolide and other, as yet undetermined, low molecular weight products. This degradation pathway accounts for the relative rates of removal for specific carotenoids (fucoxanthin = fucoxanthinol > diadinoxanthin > diatoxanthin = carotene), the distribution of carotenoids reported by Wpatts and Maxwell (1977) and C ARDOSOet al. (1978) in ancient sediments, the occurrence of novel carotenoid transformation products in surface sediments reported by r pidout et al. (1984), and the distribution of loliolides in recent sediments recovered from the Namibian shelf reported by k plok et al. (1984a,b). We predict that loliolide and isololiolide will inherit a specific stereochemistry from their carotenoid precursors, but that dihydroactinidiolide will be racemic. For every μmole of fucoxanthin degraded in Peru sediments, 0.7-1.1 μmole of loliolide is produced. Summation of fucoxanthin and loliolide at each subsurface horizon yields an estimate of the total deposition of fucoxanthin at t = 0. Throughout the 0-20 cm depth of our samples, this parameter is remarkably constant to ±16%. Individual horizons exhibit excursions which may reflect changes in surface productivity. Extrapolation of our measurements to deeper sediments may therefore be of some value in deciphering questions on environmental conditions of deposition and

  1. Disentangling the fossil world from the deep biosphere in marine sediment

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, J. B.; Walsh, E. A.; D'Hondt, S.

    2015-12-01

    DNA in marine sediment contains both detrital sequences and sequences from organisms native to the sediment. The demarcation between these two pools and their rates of respective turnover as sediment ages are generally unknown. Here we address these issues by quantifying the total extractable DNA pool and comparing it to the fraction of sequenced chloroplast DNA (cpDNA) in sediment from two sites in the Bering Sea. Sediment at both of these sites is initially oxic, but transitions to suboxic and anoxic within approximately hundred years. In our samples, cpDNA as a tracer of detrital DNA is dominated by identifiable phylotypes that match specific siliceous microfossil taxa. The fraction of sequences comprised by cpDNA decreases with increasing sediment age over hundreds of thousands of years (kyr) to 1.4 million years (Ma), but does not reach zero at either site. When we take into account the overall shrinkage of the DNA pool, this cpDNA fraction follows a power-law function, suggesting that the residual cpDNA becomes increasingly recalcitrant with age. This increasing recalcitrance can be explained by biological activity decreasing with sediment age and / or by preferential long-term survival of only the most thoroughly protected DNA. In either case, this trend suggests that DNA persisting beyond an initial period (ca. 100 - 200 kyr at our sites) has an increased chance of preservation at depth. The association of sequenced cpDNA reads with specific siliceous microfossil taxa suggests that microfossils may help to preserve DNA; DNA from such taxa may be useful for studies of paleoenvironmental conditions and biological evolution on timescales that approach or exceed one million years.

  2. Sulfate reduction and methanogenesis in marine sediments

    NASA Technical Reports Server (NTRS)

    Oremland, R. S.; Taylor, B. F.

    1978-01-01

    Methanogenesis and sulfate-reduction were followed in laboratory incubations of sediments taken from tropical seagrass beds. Methanogenesis and sulfate-reduction occurred simultaneously in sediments incubated under N2, thereby indicating that the two processes are not mutually exclusive. Sediments incubated under an atmosphere of H2 developed negative pressures due to the oxidation of H2 by sulfate-respiring bacteria. H2 also stimulated methanogenesis, but methanogenic bacteria could not compete for H2 with the sulfate-respiring bacteria.

  3. Culture-dependent and independent studies of microbial diversity in highly copper-contaminated Chilean marine sediments.

    PubMed

    Besaury, Ludovic; Marty, Florence; Buquet, Sylvaine; Mesnage, Valérie; Muyzer, Gerard; Quillet, Laurent

    2013-02-01

    Cultivation and molecular-based approaches were used to study microbial diversity in two Chilean marine sediments contaminated with high (835 ppm) and very high concentrations of copper (1,533 ppm). The diversity of cultivable bacteria resistant to copper was studied at oxic and anoxic conditions, focusing on sulfate-, thiosulfate-, and iron-reducing bacteria. For both sediments, the cultivable bacteria isolated at oxic conditions were mostly affiliated to the genus Bacillus, while at anoxic conditions the majority of the cultivable bacteria found were closely related to members of the genera Desulfovibrio, Sphingomonas, and Virgibacillus. Copper resistance was between 100 and 400 ppm, with the exception of a strain affiliated to members of the genus Desulfuromonas, which was resistant up to 1,000 ppm of copper. In parallel, cloning and sequencing of 16S rRNA was performed to study the total bacterial diversity in the sediments. A weak correlation was observed between the isolated strains and the 16S rRNA operational taxonomic units detected. The presence of copper resistance genes (copA, cusA, and pcoA) was tested for all the strains isolated; only copA was detected in a few isolates, suggesting that other copper resistance mechanisms could be used by the bacteria in those highly copper-contaminated sediments. PMID:22976340

  4. Cenozoic marine geochemistry of thallium deduced from isotopic studies of ferromanganese crusts and pelagic sediments

    USGS Publications Warehouse

    Rehkamper, M.; Frank, M.; Hein, J.R.; Halliday, A.

    2004-01-01

    Cenozoic records of Tl isotope compositions recorded by ferromanganese (Fe-Mn) crusts have been obtained. Such records are of interest because recent growth surfaces of Fe-Mn crusts display a nearly constant Tl isotope fractionation relative to seawater. The time-series data are complemented by results for bulk samples and leachates of various marine sediments. Oxic pelagic sediments and anoxic marine deposits can be distinguished by their Tl isotope compositions. Both pelagic clays and biogenic oozes are typically characterized by ??205Tl greater than +2.5, whereas anoxic sediments have ??205Tl of less than -1.5 (??205Tl is the deviation of the 205Tl/203Tl isotope ratio of a sample from NIST SRM 997 Tl in parts per 104). Leaching experiments indicate that the high ??205Tl values of oxic sediments probably reflect authigenic Fe-Mn oxyhydroxides. Time-resolved Tl isotope compositions were obtained from six Fe-Mn crusts from the Atlantic, Indian, and Pacific oceans and a number of observations indicate that these records were not biased by diagenetic alteration. Over the last 25 Myr, the data do not show isotopic variations that significantly exceed the range of Tl isotope compositions observed for surface layers of Fe-Mn crusts distributed globally (??205 Tl=+12.8??1.2). This indicates that variations in deep-ocean temperature were not recorded by Tl isotopes. The results most likely reflect a constant Tl isotope composition for seawater. The growth layers of three Fe-Mn crusts that are older than 25 Ma show a systematic increase of ??205Tl with decreasing age, from about +6 at 60-50 Ma to about +12 at 25 Ma. These trends are thought to be due to variations in the Tl isotope composition of seawater, which requires that the oceans of the early Cenozoic either had smaller output fluxes or received larger input fluxes of Tl with low ??205Tl. Larger inputs of isotopically light Tl may have been supplied by benthic fluxes from reducing sediments, rivers, and/or volcanic

  5. Archaea of the Miscellaneous Crenarchaeotal Group are abundant, diverse and widespread in marine sediments

    PubMed Central

    Kubo, Kyoko; Lloyd, Karen G; F Biddle, Jennifer; Amann, Rudolf; Teske, Andreas; Knittel, Katrin

    2012-01-01

    Members of the highly diverse Miscellaneous Crenarchaeotal Group (MCG) are globally distributed in various marine and continental habitats. In this study, we applied a polyphasic approach (rRNA slot blot hybridization, quantitative PCR (qPCR) and catalyzed reporter deposition FISH) using newly developed probes and primers for the in situ detection and quantification of MCG crenarchaeota in diverse types of marine sediments and microbial mats. In general, abundance of MCG (cocci, 0.4 μm) relative to other archaea was highest (12–100%) in anoxic, low-energy environments characterized by deeper sulfate depletion and lower microbial respiration rates (P=0.06 for slot blot and P=0.05 for qPCR). When studied in high depth resolution in the White Oak River estuary and Hydrate Ridge methane seeps, changes in MCG abundance relative to total archaea and MCG phylogenetic composition did not correlate with changes in sulfate reduction or methane oxidation with depth. In addition, MCG abundance did not vary significantly (P>0.1) between seep sites (with high rates of methanotrophy) and non-seep sites (with low rates of methanotrophy). This suggests that MCG are likely not methanotrophs. MCG crenarchaeota are highly diverse and contain 17 subgroups, with a range of intragroup similarity of 82 to 94%. This high diversity and widespread distribution in subsurface sediments indicates that this group is globally important in sedimentary processes. PMID:22551871

  6. The role of denitrification on arsenite oxidation and arsenic mobility in an anoxic sediment column model with activated alumina.

    PubMed

    Sun, Wenjie; Sierra-Alvarez, Reyes; Field, Jim A

    2010-12-01

    Arsenite (As(III)) is the predominant arsenic (As) species in reducing environments. As(III) is less strongly adsorbed than As(V) at circumneutral pH conditions by common non-iron metal oxides in sediments such as those of aluminum. Therefore, oxidation of As(III) to As(V) could contribute to an improved immobilization of As and thus help mitigate As contamination in groundwater. Microbial oxidation of As(III) is known to readily under aerobic conditions, however, the dissolved oxygen (O₂) concentration in groundwater may be limited due to the poor solubility of O₂ and its high chemical reactivity with reduced compounds. Nitrate (NO₃⁻), can be considered as an alternative electron acceptor, which can support oxidation of As(III) to As(V) by denitrifying bacteria. In this study, two up-flow sediment columns packed with activated alumina (AA) were utilized to demonstrate the role of denitrification on the oxidation of As(III) to As(V) and its contribution to improved As adsorption onto AA. One column was supplied with NO₃⁻(C1) and its performance was compared with a control column lacking NO₃⁻(C2). During most of the operation when the pH was in the circumneutral range (days 50-250), the release of arsenic was greater from C2 compared to C1. The effluent As concentrations started increasing on days 60 and 100 in C2 and C1, respectively. Complete breakthrough started on day 200 in C2; whereas in C1, complete breakthrough was never achieved. The effluent and solid phase As speciation was dominated by As(V) in C1, indicating the occurrence of As(III) oxidation due to NO₃⁻; whereas in C2, only As(III) was dominant. This study illustrates a bioremediation or natural attenuation process based on anoxic microbial NO₃⁻-dependent oxidation of As(III) to more readily adsorbed As(V) as a means to enhance the immobilization of As on alumina oxide particles in subsurface environments.

  7. Pertechnetate (TcO4-) reduction by reactive ferrous iron forms in naturally anoxic, redox transition zone sediments from the Hanford Site, USA

    SciTech Connect

    Peretyazhko, Tetyana; Zachara, John M.; Kukkadapu, Ravi K.; Heald, Steve M.; Kutnyakov, Igor V.; Resch, Charles T.; Arey, Bruce W.; Wang, Chong M.; Kovarik, Libor; Phillips, Jerry L.; Moore, Dean A.

    2012-09-01

    Technetium is an important environmental contaminant introduced by the processing and disposal of irradiated nuclear fuel and atmospheric nuclear tests. Under oxic conditions technetium is soluble and exists as pertechnatate anion (TcO4-), while under anoxic conditions Tc is usually insoluble and exists as precipitated Tc(IV). Here we investigated abiotic Tc(VII) reduction in mineralogically heterogeneous, Fe(II)-containing sediments. The sediments were collected from a 55 m borehole that sampled a semi-confined aquifer at the Hanford Site, USA that contained a dramatic redox transition zone. One oxic facies (18.0-18.3 m) and five anoxic facies (18.3-18.6 m, 30.8-31.1 m, 39.0-39.3 m, 47.2-47.5 m and 51.5-51.8 m) were selected for this study. Chemical extractions, X-ray diffraction, electron microscopy, and Mössbauer spectroscopy were applied to characterize the Fe(II) mineral suite that included: Fe(II)-phyllosilicates, pyrite, magnetite and siderite. The Fe(II) mineral phase distribution differed between the sediments. Sediment suspensions were adjusted to the same 0.5 M HCl extracted Fe(II) concentration (0.6 mM) for Tc(VII) reduction experiments. Aqueous Fe was low in all sediment suspensions (<2 μM) and below the Fe(II)aq detection limit (10 μM). Technetium(VII) reduction occurred in all anoxic sediments at depths greater than 18.3 m and reaction time differed significantly between the sediments (8-219 d). Mössbauer analysis of the Tc-reacted, 30.8-31.1 m sediment confirmed that Tc(VII) was reduced by solid-phase Fe(II), with siderite and Fe(II)-containing phyllosilicates implicated as redox reactive phases. Technetium-XAS analysis demonstrated that Tc associated with sediments was in the Tc(IV) valence state and immobilized as clusters of a TcO2·nH2O-like phase. The speciation of redox product Tc(IV) was not affected by reduction rate or Fe(II) mineralogy.

  8. In situ Measurement of Pore-Water pH in Anoxic Sediments Using Laser Raman Spectrometry

    NASA Astrophysics Data System (ADS)

    Peltzer, E. T.; Luna, M.; Walz, P. M.; Zhang, X.; Brewer, P. G.

    2010-12-01

    Accurate measurement of the geochemical properties of sediment pore waters is of fundamental importance in ocean geochemistry and microbiology. Recent work has shown that the properties of pore waters can be measured rapidly in situ with a novel Raman based insertion probe (Zhang et al., 2010), and that data obtained from anoxic sediments on in situ dissolved methane concentrations are very different (~30x) than from recovered cores due the large scale degassing that occurs during core recovery (Zhang et al., submitted). Degassing of methane must carry with it via Henry’s Law partioning significant quantities of H2S, which is clearly detectable by smell during sample processing, and thus in situ measurement of H2S is also highly desirable. In practice, dissolved H2S is partitioned between the HS- and H2S species as a function of pH with pKa ~7 for the acid dissociation reaction. Since both species are Raman active full determination of the sulfide system is possible if the relative Raman cross sections are known. The diagenetic equations for these reactions are commonly summarized as: 2CH2O + SO4= ↔ 2HCO3- + H2S CH4 + SO4= ↔ HCO3- + HS- + H2O Three of the major components of these equations, CH4, SO4=, and H2S/HS-, are all observable directly by Raman spectroscopy; but the detection of HCO3- presents a challenge due to its low Raman cross section and thus poor sensitivity. We show that pore water pH, which is a good estimator of HCO3- if total CO2 or alkalinity are known, can be measured by observing the H2S / HS- ratio via the equation: pH = pKa + log([HS-]/[H2S]) thereby fully constraining these equations within a single measurement protocol. The Raman peak for HS- is at 2573 cm-1 and for H2S is at 2592 cm-1; thus the peaks are well separated and may easily be deconvoluted from the observed spectrum. We have determined the relative Raman cross sections by a series of laboratory measurements over a range of pH and by using the definition that when pH = p

  9. Remnants of marine bacterial communities can be retrieved from deep sediments in lakes of marine origin.

    PubMed

    Langenheder, Silke; Comte, Jérôme; Zha, Yinghua; Samad, Md Sainur; Sinclair, Lucas; Eiler, Alexander; Lindström, Eva S

    2016-08-01

    Some bacteria can be preserved over time in deep sediments where they persist either in dormant or slow-growing vegetative stages. Here, we hypothesized that such cells can be revived when exposed to environmental conditions similar to those before they were buried in the sediments. To test this hypothesis, we collected bacteria from sediment samples of different ages (140-8500 calibrated years before present, cal BP) from three lakes that differed in the timing of their physical isolation from the Baltic Sea following postglacial uplift. After these bacterial communities were grown in sterile water from the Baltic Sea, we determined the proportion of 16S rRNA sequence reads associated with marine habitats by extracting the environment descriptive terms of homologous sequences retrieved from public databases. We found that the proportion of reads associated with marine descriptive term was significantly higher in cultures inoculated with sediment layers formed under Baltic conditions and where salinities were expected to be similar to current levels. Moreover, a similar pattern was found in the original sediment layers. Our study, therefore, suggests that remnants of marine bacterial communities can be preserved in sediments over thousands of years and can be revived from deep sediments in lakes of marine origin.

  10. Remnants of marine bacterial communities can be retrieved from deep sediments in lakes of marine origin.

    PubMed

    Langenheder, Silke; Comte, Jérôme; Zha, Yinghua; Samad, Md Sainur; Sinclair, Lucas; Eiler, Alexander; Lindström, Eva S

    2016-08-01

    Some bacteria can be preserved over time in deep sediments where they persist either in dormant or slow-growing vegetative stages. Here, we hypothesized that such cells can be revived when exposed to environmental conditions similar to those before they were buried in the sediments. To test this hypothesis, we collected bacteria from sediment samples of different ages (140-8500 calibrated years before present, cal BP) from three lakes that differed in the timing of their physical isolation from the Baltic Sea following postglacial uplift. After these bacterial communities were grown in sterile water from the Baltic Sea, we determined the proportion of 16S rRNA sequence reads associated with marine habitats by extracting the environment descriptive terms of homologous sequences retrieved from public databases. We found that the proportion of reads associated with marine descriptive term was significantly higher in cultures inoculated with sediment layers formed under Baltic conditions and where salinities were expected to be similar to current levels. Moreover, a similar pattern was found in the original sediment layers. Our study, therefore, suggests that remnants of marine bacterial communities can be preserved in sediments over thousands of years and can be revived from deep sediments in lakes of marine origin. PMID:26929161

  11. Marine clathrate mining and sediment separation

    DOEpatents

    Borns, David J.; Hinkebein, Thomas E.; Lynch, Richard W.; Northrop, David A.

    2001-01-01

    A method and apparatus for mining of hydrocarbons from a hydrocarbon-containing clathrate such as is found on the ocean floor. The hydrocarbon containing clathrate is disaggregated from sediment by first disrupting clathrate-containing strata using continuous mining means such as a rotary tilling drum, a fluid injector, or a drill. The clathrate-rich portion of sediment thus disrupted from the sea floor strata are carried through the apparatus to regions of relative lower pressure and/or relative higher temperature where the clathrate further dissociates into component hydrocarbons and water. The hydrocarbon is recovered with the assistance of a gas that is injected and buoys the hydrocarbon containing clathrate helping it to rise to regions of lower pressure and temperature where hydrocarbon is released. The sediment separated from the hydrocarbon returns to the ocean floor.

  12. Meiofauna increases bacterial denitrification in marine sediments

    PubMed Central

    Bonaglia, S.; Nascimento, F. J. A; Bartoli, M.; Klawonn, I.; Brüchert, V.

    2014-01-01

    Denitrification is a critical process that can alleviate the effects of excessive nitrogen availability in aquatic ecosystems subject to eutrophication. An important part of denitrification occurs in benthic systems where bioturbation by meiofauna (invertebrates <1 mm) and its effect on element cycling are still not well understood. Here we study the quantitative impact of meiofauna populations of different abundance and diversity, in the presence and absence of macrofauna, on nitrate reduction, carbon mineralization and methane fluxes. In sediments with abundant and diverse meiofauna, denitrification is double that in sediments with low meiofauna, suggesting that meiofauna bioturbation has a stimulating effect on nitrifying and denitrifying bacteria. However, high meiofauna densities in the presence of bivalves do not stimulate denitrification, while dissimilatory nitrate reduction to ammonium rate and methane efflux are significantly enhanced. We demonstrate that the ecological interactions between meio-, macrofauna and bacteria are important in regulating nitrogen cycling in soft-sediment ecosystems. PMID:25318852

  13. Assessment of Density Variations of Marine Sediments with Ocean and Sediment Depths

    PubMed Central

    Tenzer, R.; Gladkikh, V.

    2014-01-01

    We analyze the density distribution of marine sediments using density samples taken from 716 drill sites of the Deep Sea Drilling Project (DSDP). The samples taken within the upper stratigraphic layer exhibit a prevailing trend of the decreasing density with the increasing ocean depth (at a rate of −0.05 g/cm3 per 1 km). Our results confirm findings of published studies that the density nonlinearly increases with the increasing sediment depth due to compaction. We further establish a 3D density model of marine sediments and propose theoretical models of the ocean-sediment and sediment-bedrock density contrasts. The sediment density-depth equation approximates density samples with an average uncertainty of about 10% and better represents the density distribution especially at deeper sections of basin sediments than a uniform density model. The analysis of DSDP density data also reveals that the average density of marine sediments is 1.70 g/cm3 and the average density of the ocean bedrock is 2.9 g/cm3. PMID:24744686

  14. The "Oil-Spill Snorkel": an innovative bioelectrochemical approach to accelerate hydrocarbons biodegradation in marine sediments.

    PubMed

    Cruz Viggi, Carolina; Presta, Enrica; Bellagamba, Marco; Kaciulis, Saulius; Balijepalli, Santosh K; Zanaroli, Giulio; Petrangeli Papini, Marco; Rossetti, Simona; Aulenta, Federico

    2015-01-01

    This study presents the proof-of-concept of the "Oil-Spill Snorkel": a novel bioelectrochemical approach to stimulate the oxidative biodegradation of petroleum hydrocarbons in sediments. The "Oil-Spill Snorkel" consists of a single conductive material (the snorkel) positioned suitably to create an electrochemical connection between the anoxic zone (the contaminated sediment) and the oxic zone (the overlying O2-containing water). The segment of the electrode buried within the sediment plays a role of anode, accepting electrons deriving from the oxidation of contaminants. Electrons flow through the snorkel up to the part exposed to the aerobic environment (the cathode), where they reduce oxygen to form water. Here we report the results of lab-scale microcosms setup with marine sediments and spiked with crude oil. Microcosms containing one or three graphite snorkels and controls (snorkel-free and autoclaved) were monitored for over 400 days. Collectively, the results of this study confirmed that the snorkels accelerate oxidative reactions taking place within the sediment, as documented by a significant 1.7-fold increase (p = 0.023, two-tailed t-test) in the cumulative oxygen uptake and 1.4-fold increase (p = 0.040) in the cumulative CO2 evolution in the microcosms containing three snorkels compared to snorkel-free controls. Accordingly, the initial rate of total petroleum hydrocarbons (TPH) degradation was also substantially enhanced. Indeed, while after 200 days of incubation a negligible degradation of TPH was noticed in snorkel-free controls, a significant reduction of 12 ± 1% (p = 0.004) and 21 ± 1% (p = 0.001) was observed in microcosms containing one and three snorkels, respectively. Although, the "Oil-Spill Snorkel" potentially represents a groundbreaking alternative to more expensive remediation options, further research efforts are needed to clarify factors and conditions affecting the snorkel-driven biodegradation processes and to identify suitable

  15. Dynamics of bacterial assemblages and removal of polycyclic aromatic hydrocarbons in oil-contaminated coastal marine sediments subjected to contrasted oxygen regimes.

    PubMed

    Militon, Cécile; Jézéquel, Ronan; Gilbert, Franck; Corsellis, Yannick; Sylvi, Léa; Cravo-Laureau, Cristiana; Duran, Robert; Cuny, Philippe

    2015-10-01

    To study the impact of oxygen regimes on the removal of polycylic aromatic hydrocarbons (PAHs) in oil-spill-affected coastal marine sediments, we used a thin-layer incubation method to ensure that the incubated sediment was fully oxic, anoxic, or was influenced by oxic-anoxic switches without sediment stirring. Hydrocarbon content and microbial assemblages were followed during 60 days to determine PAH degradation kinetics and microbial community dynamics according to the oxygenation regimes. The highest PAH removal, with 69 % reduction, was obtained at the end of the experiment under oxic conditions, whereas weaker removals were obtained under oscillating and anoxic conditions (18 and 12 %, respectively). Bacterial community structure during the experiment was determined using a dual 16S rRNA genes/16S rRNA transcripts approach, allowing the characterization of metabolically active bacteria responsible for the functioning of the bacterial community in the contaminated sediment. The shift of the metabolically active bacterial communities showed that the selection of first responders belonged to Pseudomonas spp. and Labrenzia sp. and included an unidentified Deltaproteobacteria-irrespective of the oxygen regime-followed by the selection of late responders adapted to the oxygen regime. A novel unaffiliated phylotype (B38) was highly active during the last stage of the experiment, at which time, the low-molecular-weight (LMW) PAH biodegradation rates were significant for permanent oxic- and oxygen-oscillating conditions, suggesting that this novel phylotype plays an active role during the restoration phase of the studied ecosystem.

  16. Dynamics of bacterial assemblages and removal of polycyclic aromatic hydrocarbons in oil-contaminated coastal marine sediments subjected to contrasted oxygen regimes.

    PubMed

    Militon, Cécile; Jézéquel, Ronan; Gilbert, Franck; Corsellis, Yannick; Sylvi, Léa; Cravo-Laureau, Cristiana; Duran, Robert; Cuny, Philippe

    2015-10-01

    To study the impact of oxygen regimes on the removal of polycylic aromatic hydrocarbons (PAHs) in oil-spill-affected coastal marine sediments, we used a thin-layer incubation method to ensure that the incubated sediment was fully oxic, anoxic, or was influenced by oxic-anoxic switches without sediment stirring. Hydrocarbon content and microbial assemblages were followed during 60 days to determine PAH degradation kinetics and microbial community dynamics according to the oxygenation regimes. The highest PAH removal, with 69 % reduction, was obtained at the end of the experiment under oxic conditions, whereas weaker removals were obtained under oscillating and anoxic conditions (18 and 12 %, respectively). Bacterial community structure during the experiment was determined using a dual 16S rRNA genes/16S rRNA transcripts approach, allowing the characterization of metabolically active bacteria responsible for the functioning of the bacterial community in the contaminated sediment. The shift of the metabolically active bacterial communities showed that the selection of first responders belonged to Pseudomonas spp. and Labrenzia sp. and included an unidentified Deltaproteobacteria-irrespective of the oxygen regime-followed by the selection of late responders adapted to the oxygen regime. A novel unaffiliated phylotype (B38) was highly active during the last stage of the experiment, at which time, the low-molecular-weight (LMW) PAH biodegradation rates were significant for permanent oxic- and oxygen-oscillating conditions, suggesting that this novel phylotype plays an active role during the restoration phase of the studied ecosystem. PMID:25997808

  17. Ocean currents shape the microbiome of Arctic marine sediments.

    PubMed

    Hamdan, Leila J; Coffin, Richard B; Sikaroodi, Masoumeh; Greinert, Jens; Treude, Tina; Gillevet, Patrick M

    2013-04-01

    Prokaryote communities were investigated on the seasonally stratified Alaska Beaufort Shelf (ABS). Water and sediment directly underlying water with origin in the Arctic, Pacific or Atlantic oceans were analyzed by pyrosequencing and length heterogeneity-PCR in conjunction with physicochemical and geographic distance data to determine what features structure ABS microbiomes. Distinct bacterial communities were evident in all water masses. Alphaproteobacteria explained similarity in Arctic surface water and Pacific derived water. Deltaproteobacteria were abundant in Atlantic origin water and drove similarity among samples. Most archaeal sequences in water were related to unclassified marine Euryarchaeota. Sediment communities influenced by Pacific and Atlantic water were distinct from each other and pelagic communities. Firmicutes and Chloroflexi were abundant in sediment, although their distribution varied in Atlantic and Pacific influenced sites. Thermoprotei dominated archaea in Pacific influenced sediments and Methanomicrobia dominated in methane-containing Atlantic influenced sediments. Length heterogeneity-PCR data from this study were analyzed with data from methane-containing sediments in other regions. Pacific influenced ABS sediments clustered with Pacific sites from New Zealand and Chilean coastal margins. Atlantic influenced ABS sediments formed another distinct cluster. Density and salinity were significant structuring features on pelagic communities. Porosity co-varied with benthic community structure across sites and methane did not. This study indicates that the origin of water overlying sediments shapes benthic communities locally and globally and that hydrography exerts greater influence on microbial community structure than the availability of methane.

  18. Reburial of fossil organic carbon in marine sediments.

    PubMed

    Dickens, Angela F; Gélinas, Yves; Masiello, Caroline A; Wakeham, Stuart; Hedges, John I

    2004-01-22

    Marine sediments act as the ultimate sink for organic carbon, sequestering otherwise rapidly cycling carbon for geologic timescales. Sedimentary organic carbon burial appears to be controlled by oxygen exposure time in situ, and much research has focused on understanding the mechanisms of preservation of organic carbon. In this context, combustion-derived black carbon has received attention as a form of refractory organic carbon that may be preferentially preserved in soils and sediments. However, little is understood about the environmental roles, transport and distribution of black carbon. Here we apply isotopic analyses to graphitic black carbon samples isolated from pre-industrial marine and terrestrial sediments. We find that this material is terrestrially derived and almost entirely depleted of radiocarbon, suggesting that it is graphite weathered from rocks, rather than a combustion product. The widespread presence of fossil graphitic black carbon in sediments has therefore probably led to significant overestimates of burial of combustion-derived black carbon in marine sediments. It could be responsible for biasing radiocarbon dating of sedimentary organic carbon, and also reveals a closed loop in the carbon cycle. Depending on its susceptibility to oxidation, this recycled carbon may be locked away from the biologically mediated carbon cycle for many geologic cycles.

  19. Low bacterial diversity and high labile organic matter concentrations in the sediments of the Medee deep-sea hypersaline anoxic basin.

    PubMed

    Akoumianaki, Ioanna; Nomaki, Hidetaka; Pachiadaki, Maria; Kormas, Konstantinos Ar; Kitazato, Hiroshi; Tokuyama, Hidekazu

    2012-01-01

    Studies in the center and margin of the Medee Basin, a Mediterranean deep-sea hypersaline anoxic basin, and at a reference site during Penelope cruise (2007), revealed the existence of a 7 m-thick halocline, with high salinity (328 psu), and high sedimentary organic carbon and biopolymer concentrations. The 194 16S rRNA sequences retrieved were grouped into 118 unique phylotypes. Pseudomonas gessardii, dominated in the center, while 33 phylotypes were detected at the margin and 73 at the reference site. The study suggested conditions hostile to bacteria in the sediments of the Medee Basin and preservation of sedimentary labile organic matter. PMID:22504432

  20. Occurrence of Priming in the Degradation of Lignocellulose in Marine Sediments

    PubMed Central

    Gontikaki, Evangelia; Thornton, Barry; Cornulier, Thomas; Witte, Ursula

    2015-01-01

    More than 50% of terrestrially-derived organic carbon (terrOC) flux from the continents to the ocean is remineralised in the coastal zone despite its perceived high refractivity. The efficient degradation of terrOC in the marine environment could be fuelled by labile marine-derived material, a phenomenon known as “priming effect”, but experimental data to confirm this mechanism are lacking. We tested this hypothesis by treating coastal sediments with 13C-lignocellulose, as a proxy for terrOC, with and without addition of unlabelled diatom detritus that served as the priming inducer. The occurrence of priming was assessed by the difference in lignocellulose mineralisation between diatom-amended treatments and controls in aerobic sediment slurries. Priming of lignocellulose degradation was observed only at the initial stages of the experiment (day 7) and coincided with overall high microbial activity as exemplified by total CO2 production. Lignocellulose mineralisation did not differ consistently between diatom treatments and control for the remaining experimental time (days 14–28). Based on this pattern, we hypothesize that the faster initiation of lignocellulose mineralisation in diatom-amended treatments is attributed to the decomposition of accessible polysaccharide components within the lignocellulose complex by activated diatom degraders. The fact that diatom-degraders contributed to lignocellulose degradation was also supported by the different patterns in 13C-enrichment of phospholipid fatty acids between treatments. Although we did not observe differences between treatments in the total quantity of respired lignocellulose at the end of the experiment, differences in timing could be important in natural ecosystems where the amount of time that a certain compound is subject to aerobic degradation before burial to deeper anoxic sediments may be limited. PMID:26633175

  1. Occurrence of Priming in the Degradation of Lignocellulose in Marine Sediments.

    PubMed

    Gontikaki, Evangelia; Thornton, Barry; Cornulier, Thomas; Witte, Ursula

    2015-01-01

    More than 50% of terrestrially-derived organic carbon (terrOC) flux from the continents to the ocean is remineralised in the coastal zone despite its perceived high refractivity. The efficient degradation of terrOC in the marine environment could be fuelled by labile marine-derived material, a phenomenon known as "priming effect", but experimental data to confirm this mechanism are lacking. We tested this hypothesis by treating coastal sediments with 13C-lignocellulose, as a proxy for terrOC, with and without addition of unlabelled diatom detritus that served as the priming inducer. The occurrence of priming was assessed by the difference in lignocellulose mineralisation between diatom-amended treatments and controls in aerobic sediment slurries. Priming of lignocellulose degradation was observed only at the initial stages of the experiment (day 7) and coincided with overall high microbial activity as exemplified by total CO2 production. Lignocellulose mineralisation did not differ consistently between diatom treatments and control for the remaining experimental time (days 14-28). Based on this pattern, we hypothesize that the faster initiation of lignocellulose mineralisation in diatom-amended treatments is attributed to the decomposition of accessible polysaccharide components within the lignocellulose complex by activated diatom degraders. The fact that diatom-degraders contributed to lignocellulose degradation was also supported by the different patterns in 13C-enrichment of phospholipid fatty acids between treatments. Although we did not observe differences between treatments in the total quantity of respired lignocellulose at the end of the experiment, differences in timing could be important in natural ecosystems where the amount of time that a certain compound is subject to aerobic degradation before burial to deeper anoxic sediments may be limited. PMID:26633175

  2. Influence of biochar amendments on marine sediment trace metal bioavailability

    NASA Astrophysics Data System (ADS)

    Gehrke, G. E.; Hsu-Kim, H.

    2014-12-01

    Biochar has become a desirable material for use in agricultural application to enhance soil quality and in-situ soil and sediment remediation to immobilize organic contaminants. We investigated the effects of biochar sediment amendments on the bioavailability of a suite of inorganic trace metals (Cr, Co, Ni, Cu, Zn, Pb) in contaminated sediments from multiple sites in Elizabeth River, VA. We incubated sediments in microcosms with a variety of water column redox and salinity conditions and compared sediments amended with two types of woody biochar to sediments amended with charcoal activated carbon and unamended sediments. We leached sediments in artificial gut fluid mimic of the benthic invertebrate Arenicola marina as a measure of bioavailability of the trace metals analyzed. In unamended anaerobic sediments, the gut fluid mimic leachable fraction of each trace metal is 1-4% of the total sediment concentration for each metal. Initial results indicate that in anaerobic microcosms, woody biochar sediment amendments (added to 5% dry wt) decrease the gut fluid mimic leachable fraction by 30-90% for all trace metals analyzed, and have comparable performance to charcoal activated carbon amendments. However, in microcosms without controlled redox conditions, woody biochar amendments increase the bioavailable fraction of Ni and Cu by up to 80%, while decreasing the bioavailable fraction of Co, Zn, and Pb by approximately 50%; charcoal activated carbon amendments decreased the bioavailability of all trace metals analyzed by approximately 20%. In microcosms without an overlying water column, biochar and activated carbon amendments had no significant effects on trace metal bioavailability. This research demonstrates that biochar can effectively decrease the bioavailability of trace metals in marine sediments, but its efficiency is metal-specific, and environmental conditions impact biochar performance.

  3. Evaluating Sediment Stability at Offshore Marine Hydrokinetic Energy Facilities

    NASA Astrophysics Data System (ADS)

    Jones, C. A.; Magalen, J.; Roberts, J.; Chang, G.

    2014-12-01

    Development of offshore alternative energy production methods through the deployment of Marine Hydrokinetic (MHK) devices (e.g. wave, tidal, and wind generators) in the United States continues at a rapid pace, with significant public and private investment in recent years. The installation of offshore MHK systems includes cabling to the shoreline and some combination of bottom foundation (e.g., piles, gravity bases, suction buckets) or anchored floating structure. Installation of any of this infrastructure at the seabed may affect coastal sediment dynamics. It is, therefore, necessary to evaluate the interrelationships between hydrodynamics and seabed dynamics and the effects of MHK foundations and cables on sediment transport. If sufficient information is known about the physical processes and sediment characteristics of a region, hydrodynamic and sediment transport models may be developed to evaluate near and far-field sediment transport. The ultimate goal of these models and methods is to quantitatively evaluate changes to the baseline seabed stability due to the installation of MHK farms in the water. The objective of the present study is to evaluate and validate wave, current, and sediment transport models (i.e., a site analysis) that may be used to estimate risk of sediment mobilization and transport. While the methodology and examples have been presented in a draft guidance document (Roberts et al., 2013), the current report presents an overall strategy for model validation, specifically for a case study in the Santa Cruz Bight, Monterey Bay, CA. Innovative techniques to quantify the risk of sediment mobility has been developed to support these investigations. Public domain numerical models are utilized to estimate the near-shore wave climate (SWAN: Simulating Waves Near-shore) and circulation and sediment transport (EFDC: Environmental Fluid Dynamics Code) regimes. The models were validated with field hydrodynamic data. Sediment size information was

  4. Three manganese oxide-rich marine sediments harbor similar communities of acetate-oxidizing manganese-reducing bacteria.

    PubMed

    Vandieken, Verona; Pester, Michael; Finke, Niko; Hyun, Jung-Ho; Friedrich, Michael W; Loy, Alexander; Thamdrup, Bo

    2012-11-01

    Dissimilatory manganese reduction dominates anaerobic carbon oxidation in marine sediments with high manganese oxide concentrations, but the microorganisms responsible for this process are largely unknown. In this study, the acetate-utilizing manganese-reducing microbiota in geographically well-separated, manganese oxide-rich sediments from Gullmar Fjord (Sweden), Skagerrak (Norway) and Ulleung Basin (Korea) were analyzed by 16S rRNA-stable isotope probing (SIP). Manganese reduction was the prevailing terminal electron-accepting process in anoxic incubations of surface sediments, and even the addition of acetate stimulated neither iron nor sulfate reduction. The three geographically distinct sediments harbored surprisingly similar communities of acetate-utilizing manganese-reducing bacteria: 16S rRNA of members of the genera Colwellia and Arcobacter and of novel genera within the Oceanospirillaceae and Alteromonadales were detected in heavy RNA-SIP fractions from these three sediments. Most probable number (MPN) analysis yielded up to 10(6) acetate-utilizing manganese-reducing cells cm(-3) in Gullmar Fjord sediment. A 16S rRNA gene clone library that was established from the highest MPN dilutions was dominated by sequences of Colwellia and Arcobacter species and members of the Oceanospirillaceae, supporting the obtained RNA-SIP results. In conclusion, these findings strongly suggest that (i) acetate-dependent manganese reduction in manganese oxide-rich sediments is catalyzed by members of taxa (Arcobacter, Colwellia and Oceanospirillaceae) previously not known to possess this physiological function, (ii) similar acetate-utilizing manganese reducers thrive in geographically distinct regions and (iii) the identified manganese reducers differ greatly from the extensively explored iron reducers in marine sediments. PMID:22572639

  5. Two-dimensional distribution of living benthic foraminifera in anoxic sediment layers of an estuarine mudflat (Loire estuary, France)

    NASA Astrophysics Data System (ADS)

    Thibault de Chanvalon, A.; Metzger, E.; Mouret, A.; Cesbron, F.; Knoery, J.; Rozuel, E.; Launeau, P.; Nardelli, M. P.; Jorissen, F. J.; Geslin, E.

    2015-10-01

    We present a new rapid and accurate protocol to simultaneously sample benthic living foraminifera in two dimensions in a centimetre-scale vertical grid and dissolved iron and phosphorus in two dimensions at high resolution (200 μm). Such an approach appears crucial for the study of foraminiferal ecology in highly dynamic and heterogeneous sedimentary systems, where dissolved iron shows a strong variability at the centimetre scale. On the studied intertidal mudflat of the Loire estuary, foraminiferal faunas are dominated by Ammonia tepida, which accounts for 92 % of the living (CellTracker Green(CTG)-labelled) assemblage. The vertical distribution shows a maximum density in the oxygenated 0-0.4 cm surface layer. A sharp decrease is observed in the next 2 cm, followed by a second, well-defined maximum in the suboxic sediment layer (3-8 cm depth). The presented method yields new information concerning the 2-D distribution of living A. tepida in suboxic layers. First, the identification of recent burrows by visual observation of the sediment cross section and the burrowing activity as deduced from the dissolved iron spatial distribution show no direct relation to the distribution of A. tepida at the centimetre scale. This lack of relation appears contradictory to previous studies (Aller and Aller, 1986; Berkeley et al., 2007). Next, the heterogeneity of A. tepida in the 3-8 cm depth layer was quantified by means of Moran's index to identify the scale of parameters controlling the A. tepida distribution. The results reveal horizontal patches with a characteristic length of 1-2 cm. These patches correspond to areas enriched in dissolved iron likely generated by anaerobic degradation of labile organic matter. These results suggest that the routine application of our new sampling strategy could yield important new insights about foraminiferal life strategies, improving our understanding of the role of these organisms in coastal marine ecosystems.

  6. Glacial-marine and glacial-lacustrine sedimentation in Sebago Lake, Maine: Locating the marine limit

    SciTech Connect

    Johnston, R.A.; Kelley, J.T. ); Belknap, D. . Dept. of Geological Sciences)

    1993-03-01

    The marine limit in Maine marks a sea-level highstand at approximately 13 ka. It was inferred to cross Sebago Lake near Frye Island by Thompson and Borns (1985) on the Surficial Geological Map of Maine, dividing the lake into a northern glacial-lacustrine basin and a southern glacial-marine basin. This study examined the accuracy of the mapped marine limit in the lake and the nature of glacial-lacustrine and glacial-marine facies in Maine. Recognition of the marine limit is usually based on mapped shorelines, glacial-marine deltas, and contacts with glacial-marine sediments. This study, in Maine's second largest lake, collected 100 kilometers of side-scan sonar images, 100 kilometers of seismic reflection profiles, and one core. Side-scan sonar records show coarse sand and gravel and extensive boulder fields at an inferred grounding-line position near Frye Island, where the marine limit was drawn. ORE Geopulse seismic reflection profiles reveal a basal draping unit similar to glacial-marine units identified offshore. Later channels cut more than 30 m into the basal stratified unit. In addition, till and a possible glacial-tectonic grounding-line feature were identified. Slumps and possible spring disruptions are found in several locations. The top unit is an onlapping ponded Holocene lacustrine unit. Total sediment is much thicker in the southern basin; the northern basin, >97 m deep, north of the marine limit appears to have been occupied by an ice block. Retrieved sediments include 12 meters of rhythmites. Microfossil identifications and dating will resolve the environments and time of deposition in this core.

  7. Ecotoxicological characterization of marine sediment in Kostrena coastal area.

    PubMed

    Linsak, Zeljko; Linsak, Dijana Tomić; Glad, Marin; Cenov, Arijana; Coklo, Mirna; Coklo, Miran; Manestar, Dubravko; Mićović, Vladimir

    2012-12-01

    Samples of marine sediment were taken on 4 selected sites close to the shipyard industry in Kostrena coastal area. Concentration of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and heavy metals (Cu, Pb, Zn, Hg, Fe) were analyzed from chemical-analytical and toxicological aspect. For toxicity detection, the bacterial bioluminescence test (Vibrio fisheri) was used. Concentration of total PAHs varied in the range from 697 to 7807 microg/kg dry weight in marine sediments. The concentration of PCBs in sediment was 1.1 mg/kg dry weight. The highest concentrations of heavy metals were found at the station within the shipyard. PAH toxicity was not correlated with the toxic potential of sediments. The obtained results indicate a high degree of environmental risk, especially at stations within the shipyard, with the 54% possibility of toxic effects. Chemical determination of the concentration of conventional pollutants is not sufficient for assessing the quality of the marine environment and it is necessary to use other approaches in order to evaluate the biological impact.

  8. Preservation potential of ancient plankton DNA in Pleistocene marine sediments.

    PubMed

    Boere, A C; Rijpstra, W I C; De Lange, G J; Sinninghe Damsté, J S; Coolen, M J L

    2011-09-01

    Recent studies have shown that ancient plankton DNA can be recovered from Holocene lacustrine and marine sediments, including from species that do not leave diagnostic microscopic fossils in the sediment record. Therefore, the analysis of this so-called fossil plankton DNA is a promising approach for refining paleoecological and paleoenvironmental information. However, further studies are needed to reveal whether DNA of past plankton is preserved beyond the Holocene. Here, we identified past eukaryotic plankton members based on 18S rRNA gene profiling in eastern Mediterranean Holocene and Pleistocene sapropels S1 (~9 ka), S3 (~80 ka), S4 (~105 ka), and S5 (~125 ka). The majority of preserved ~400- to 500-bp-long 18S rDNA fragments of microalgae that were studied in detail (i.e. from haptophyte algae and dinoflagellates) were found in the youngest sapropel S1, whereas their specific lipid biomarkers (long-chain alkenones and dinosterol) were also abundant in sediments deposited between 80 and 124 ka BP. The late-Pleistocene sediments mainly contained eukaryotic DNA of marine fungi and from terrestrial plants, which could have been introduced via the river Nile at the time of deposition and preserved in pollen grains. A parallel analysis of Branched and Isoprenoid Tetraethers (i.e. BIT index) showed that most of the organic matter in the eastern Mediterranean sediment record was of marine (e.g. pelagic) origin. Therefore, the predominance of terrestrial plant DNA over plankton DNA in older sapropels suggests a preferential degradation of marine plankton DNA.

  9. Biochemical and microbial features of shallow marine sediments along the Terra Nova Bay (Ross Sea, Antarctica)

    NASA Astrophysics Data System (ADS)

    Baldi, Franco; Marchetto, Davide; Pini, Francesco; Fani, Renato; Michaud, Luigi; Lo Giudice, Angelina; Berto, Daniela; Giani, Michele

    2010-09-01

    Shallow marine sediments were collected from seven stations (three of which located at Gerlache Inlet, two at Tethys Bay, one at Adelie Cove and one just beneath the Italian Research Base) along the Terra Nova Bay coast (Ross Sea, Antarctica). Their chemical, biochemical and microbiological properties were studied in order to provide further insights in the knowledge of this Antarctic benthic ecosystem. Overall, the organic carbon (OC) represented the major fraction of total carbon (TC) and displayed concentrations similar to or slightly lower than those previously measured in Antarctic bottom sediments. The biopolymeric carbon within OC ranged from 4.1% to 19.9% and showed a wide trophic range (65-834 μg g -1 d.w.). Proteins (PRT) represented on average the main biochemical class contributing to labile organic carbon, followed by lipids (LIP) and carbohydrates (CHO). The activity of aminopeptidase, β- D-glucosidase, alkaline phosphatase and esterase was checked, giving the highest values at Tethys Bay and at the deepest water sediments. The principal component analysis, which was computed considering physical, chemical (elemental and biochemical sedimentary composition) and microbiological parameters (including bacterial abundance, ectoenzymatic activities, T-RFs richness and diversity indices), allowed to obtain two main clusters ("Tethys Bay" and "other stations"). Based on data obtained, two representative 16S rRNA clone libraries using samples from Tethys Bay and Gerlache Inlet were constructed. The sequences of 171 clones were compared to those available in public databases to determine their approximate phylogenetic affiliations. Both aerobic and anaerobic bacteria were disclosed, with the majority of them affiliated with the Gamma- and Deltaproteobacteria, Bacteroidetes and Acidobacteria. The occurrence of strictly anaerobic bacteria suggests that sediments might also undergo anoxic conditions that, in turn, could favor the accumulation of PRT in respect

  10. Impact of short-term storage temperature on determination of microbial community composition and abundance in aerated forest soil and anoxic pond sediment samples.

    PubMed

    Brandt, Franziska B; Breidenbach, Björn; Brenzinger, Kristof; Conrad, Ralf

    2014-12-01

    Sampling strategy is important for unbiased analysis of the characteristics of microbial communities in the environment. During field work it is not always possible to analyze fresh samples immediately or store them frozen. Therefore, the effect of short-term storage temperature was investigated on the abundance and composition of bacterial, archaeal and denitrifying communities in environmental samples from two different sampling sites. Oxic forest soil and anoxic pond sediment were investigated by measuring microbial abundance (DNA) and transcriptional activity (RNA). Prior to investigating the effect of storage temperature, samples were immediately analyzed, in order to represent the original situation in the habitat. The effect of storage temperature was then determined after 11 days at different low temperatures (room temperature, 4 °C, −22 °C and −80 °C). Community profiling using terminal restriction fragment length polymorphism (T-RFLP) showed no significant differences between the immediately analyzed reference sample and the samples stored at different incubation temperatures, both for DNA and RNA extracts. The abundance of microbial communities was determined using quantitative PCR and it also revealed a stable community size at all temperatures tested. By contrast, incubation at an elevated temperature (37 °C) resulted in changed bacterial community composition. In conclusion, short-term storage, even at room temperature, did not affect microbial community composition, abundance and transcriptional activity in aerated forest soil and anoxic pond sediment.

  11. Detoxification of hazardous dust with marine sediment.

    PubMed

    Wei, Yu-Ling; Lin, Chang-Yuan; Wang, H Paul

    2014-08-30

    Hazardous electric arc furnace dust containing dioxins/furans and heavy metals is blended with harbor sediment, fired at 950-1100 °C to prepare lightweight aggregates. Dust addition can lower the sintering temperature by about 100 °C, as compared to a typical industrial process. After firing at 950 °C and 1050 °C, more than 99.85% of dioxins/furans originally present in the dust have been removed and/or destructed in the mix containing a dust/sediment ratio of 50:100. The heavy metals leached from all fired mixes are far below Taiwan EPA legal limits. The particle density of the lightweight aggregates always decreases with increasing firing temperature. Greater addition of the dust results in a considerably lower particle density (mostly <2.0 g cm(-3)) fired at 1050 °C and 1100 °C. However, firing at temperatures lower than 1050 °C produces no successful bloating, leading to a denser particle density (>2.0 g cm(-3)) that is typical of bricks.

  12. Mycodiversity in marine sediments contaminated by heavy metals: preliminary results

    NASA Astrophysics Data System (ADS)

    Zotti, Mirca; Carbone, Cristina; Cecchi, Grazia; Consani, Sirio; Cutroneo, Laura; Di Piazza, Simone; Gabutto, Giacomo; Greco, Giuseppe; Vagge, Greta; Capello, Marco

    2016-04-01

    Fungi represent the main decomposers of woody and herbaceous substrates in the marine ecosystems. To date there is a gap in the knowledge about the global diversity and distribution of fungi in marine habitats. On the basis of their biological diversity and their role in ecosystem processes, marine fungi may be considered one of the most attractive groups of organisms in modern biotechnology, e.g. ecotoxic metal bioaccumulation. Here we report the data about the first mycological survey in the metal contaminated coastal sediments of the Gromolo Bay. The latter is located in Ligurian Sea (Eastern Liguria, Italy) and is characterized by an enrichment of heavy metals due to pollution of Gromolo Torrent by acidic processes that interest Fe-Cu sulphide mine. 24 samples of marine sediments were collected along a linear plot in front of the shoreline in July 2015. Each sample was separated into three aliquot for mineralogical, chemical analyses and fungal characterization. The sediment samples are characterised by clay fractions (illite and chlorite), minerals of ophiolitic rocks (mainly serpentine, pyroxene and plagioclase) and quartz and are enriched some chemical elements of environmental importance (such as Cu, Zn, Pb, Cd, As). For fungal characterisation the sediment samples were inoculated in Petri dishes on different culture media (Malt Extract Agar and Rose Bengal) prepared with sea water and added with antibiotics. The inoculated dishes were incubated at 20°C in the dark for 28 days. Every week fungal growth was monitored counting the number of colonies. Later, the colonies were isolated in axenic culture for further molecular analysis. The mycodiversity evaluate on the basis of Colony Forming Units (CFU) and microfungal-morphotype characterised by macro-and micro-morphology. Until now on the 72 Petri dishes inoculated 112 CFU of filamentous fungi were counted, among these about 50 morphotypes were characterized. The quantitative results show a mean value of 4

  13. Marine dredged sediments as new materials resource for road construction.

    PubMed

    Siham, Kamali; Fabrice, Bernard; Edine, Abriak Nor; Patrick, Degrugilliers

    2008-01-01

    Large volumes of sediments are dredged each year in Europe in order to maintain harbour activities. With the new European Union directives, harbour managers are encouraged to find environmentally sound solutions for these materials. This paper investigates the potential uses of Dunkirk marine dredged sediment as a new material resource for road building. The mineralogical composition of sediments is evaluated using X-ray diffraction and microscopy analysis. Since sediments contain a high amount of water, a dewatering treatment has been used. Different suitable mixtures, checking specific geotechnical criteria as required in French standards, are identified. The mixtures are then optimized for an economical reuse. The mechanical tests conducted on these mixtures are compaction, bearing capacity, compression and tensile tests. The experimental results show the feasibility of the beneficial use of Dunkirk marine dredged sand and sediments as a new material for the construction of foundation and base layers for roads. Further research is now needed to prove the resistance of this new material to various environmental impacts (e.g., frost damage).

  14. In situ tensile fracture toughness of surficial cohesive marine sediments

    NASA Astrophysics Data System (ADS)

    Johnson, Bruce D.; Barry, Mark A.; Boudreau, Bernard P.; Jumars, Peter A.; Dorgan, Kelly M.

    2012-02-01

    This study reports the first in situ measurements of tensile fracture toughness, K IC, of soft, surficial, cohesive marine sediments. A newly developed probe continuously measures the stress required to cause tensile failure in sediments to depths of up to 1 m. Probe measurements are in agreement with standard laboratory methods of K IC measurements in both potter's clay and natural sediments. The data comprise in situ depth profiles from three field sites in Nova Scotia, Canada. Measured K IC at two muddy sites (median grain size of 23-50 μm) range from near zero at the sediment surface to >1,800 Pa m1/2 at 0.2 m depth. These profiles also appear to identify the bioturbated/mixed depth. K IC for a sandy site (>90% sand) is an order of magnitude lower than for the muddy sediments, and reflects the lack of cohesion/adhesion. A comparison of K IC, median grain size, and porosity in muddy sediments indicates that consolidation increases fracture strength, whereas inclusion of sand causes weakening; thus, sand-bearing layers can be easily identified in K IC profiles. K IC and vane-measured shear strength correlate strongly, which suggests that the vane measurements should perhaps be interpreted as shear fracture toughness, rather than shear strength. Comparison of in situ probe-measured values with K IC of soils and gelatin shows that sediments have a K IC range intermediate between denser compacted soils and softer, elastic gelatin.

  15. Heterotrophic euglenids from marine sediments of cape tribulation, tropical australia

    NASA Astrophysics Data System (ADS)

    Je Lee, Won

    2006-06-01

    This paper presents new data on free-living heterotrophic euglenids (Euglenozoa, Protista) that occurred in the marine sediments at Cape Tribulation, Queensland, Australia. Twenty-nine species from 9 genera are described with uninterpreted records based on light microscopy, including one new taxon: Notosolenus capetribulationi n. sp. There was little evidence for endemism because the majority of heterotrophic euglenid species encountered here have been reported or were found from other habitats.

  16. Manganese cycles in Arctic marine sediments - Climate signals or diagenesis?

    NASA Astrophysics Data System (ADS)

    März, C.; Stratmann, A.; Eckert, S.; Schnetger, B.; Brumsack, H.-J.

    2009-04-01

    In comparison to sediments from other parts of the world ocean, the inorganic geochemistry of Arctic Ocean sediments is poorly investigated. However, marked light to dark brown layers are well-known features of Quaternary Arctic sediments, and have been related to variable Mn contents. Brown layers represent intervals relatively rich in Mn (often > 1 wt.%), while yellowish-greyish intervals contain less Mn. As these brown layers are widespread in pelagic Quaternary deposits of the Arctic Ocean, there are attempts to use them as stratigraphic, age-equivalent marker horizons that are genetically related to global climate changes (e.g. Jakobsson et al., 2000; Löwemark et al., 2008). In the Arctic Ocean, other conventional stratigraphic methods often fail, therefore the use of Mn-rich layers as a chemostratigraphic tool seems to be a promising approach. However, several inorganic-geochemical and modelling studies of Mn cycles in the Arctic as well as in other parts of the world ocean have shown that multiple Mn layers in marine sediments can be created by non-steady state diagenetic processes, i.e. secondary Mn redistribution in the sediment due to microbially mediated dissolution-reprecipitation reactions (e.g. Li et al., 1969; Gobeil et al., 1997; Burdige, 2006; Katsev et al., 2006). Such biogeochemical processes can lead to rapid migration or fixation of redox boundaries in the sediment, resulting in the formation or (partial) destruction of metal-rich layers several thousands of years after sediment deposition. As this clearly would alter primary paleoenvironmental signals recorded in the sediments, we see an urgent need to unravel the real stratigraphic potential of Arctic Mn cycles before they are readily established as standard tools. For this purpose, we are studying Mn cycles in Arctic Ocean sediments recovered during R/V Polarstern expedition ARK XXIII/3 on the Mendeleev Ridge (East Siberian Sea). First results of pore water and sediment composition

  17. Modeling signal loss in surficial marine sediments containing occluded gas.

    PubMed

    Gardner, Trevor

    2003-03-01

    The presence of occluded gas in inland lakes, harbor muds, and surficial marine sediments is well documented. Surficial gassy sediments cause underlying beds to be acoustically impenetrable to seismic surveys; therefore, the modeling of signal loss arising from mudline reflection and transmission absorption is of particular interest. The Anderson and Hampton [J. Acoust. Soc. Am. 67, 1890-1903 (1980)] model for attenuation in gassy sediments was evaluated against the physical and acoustical properties of eight laboratory silty clay soils containing different amounts of occluded gas in bubbles of 0.2- to 1.8-mm diameter. The model was shown to give good agreement with measured data over the lower frequencies of bubble resonance and above resonance. It did not agree with measured data at frequencies below resonance, for which the model did not simulate the bulk properties of the gassy soils. The Mackenzie [J. Acoust. Soc. Am. 32, 221-231 (1960)] model for reflection loss was also examined for the gassy soils. The maximum reflection losses of 6 dB, at a grazing angle of 40 degrees, does not wholly support speculation by Levin [Geophysics 27, 35-47 (1962)] of highly reflective pressure-release boundaries arising from substantial reflection and absorption losses in gassy sediments. It was found that mudlines formed from sediments with significant occluded gas may be successfully penetrated, although the substantial absorption loss arising from signal transmission through the sediment prevents penetration of the surficial layers to much beyond a meter in depth.

  18. Demethylation and cleavage of dimethylsulfoniopropionate in marine intertidal sediments

    USGS Publications Warehouse

    Visscher, P.T.; Kiene, R.P.; Taylor, B.F.

    1994-01-01

    Demethylation and cleavage of dimethylsulfoniopropionate (DMSP) was measured in three different types of,intertidal marine sediments: a cyanobacterial mat, a diatom-covered tidal flat and a carbonate sediment. Consumption rates of added DMSP were highest in cyanobacterial mat slurries (59 ?? mol DMSP l-1 slurry h-1) and lower in slurries from a diatom mat and a carbonate tidal sediment (24 and 9 ??mol DMSP l-1 h-1, respectively). Dimethyl sulfide (DMS) and 3-mercaptopropionate (MPA) were produced simultaneously during DMSP consumption, indicating that cleavage and demethylation occurred at the same time. Viable counts of DMSP-utilizing bacteria revealed a population of 2 x 107 cells cm-3 sediment (90% of these cleaved DMSP to DMS, 10% demethylated DMSP to MPA) in the cyanobacterial mat, 7 x 105 cells cm-3 in the diatom mat (23% cleavers, 77% demethylators), and 9 x 104 cells cm-3 (20% cleavers and 80% demethylators) in the carbonate sediment. In slurries of the diatom mat, the rate of MPA production from added 3-methiolpropionate (MMPA) was 50% of the rate of MPA formation from DMSP. The presence of a large population of demethylating bacteria and the production of MPA from DMSP suggest that the demethylation pathway, in addition to cleavage, contributes significantly to DMSP consumption in coastal sediments.

  19. Sulfur and carbon cycling in organic-rich marine sediments

    NASA Technical Reports Server (NTRS)

    Martens, C. S.

    1985-01-01

    Nearshore, continental shelf, and slope sediments are important sites of microbially mediated carbon and sulfur cycling. Marine geochemists investigated the rates and mechanisms of cycling processes in these environments by chemical distribution studies, in situ rate measurements, and steady state kinetic modeling. Pore water chemical distributions, sulfate reduction rates, and sediment water chemical fluxes were used to describe cycling on a ten year time scale in a small, rapidly depositing coastal basin, Cape Lookout Bight, and at general sites on the upper continental slope off North Carolina, U.S.A. In combination with 210 Pb sediment accumulation rates, these data were used to establish quantitative carbon and sulfur budgets as well as the relative importance of sulfate reduction and methanogeneis as the last steps in the degradation of organic matter.

  20. A model for microbial phosphorus cycling in bioturbated marine sediments: Significance for phosphorus burial in the early Paleozoic

    NASA Astrophysics Data System (ADS)

    Dale, Andrew W.; Boyle, Richard A.; Lenton, Timothy M.; Ingall, Ellery D.; Wallmann, Klaus

    2016-09-01

    A diagenetic model is used to simulate the diagenesis and burial of particulate organic carbon (Corg) and phosphorus (P) in marine sediments underlying anoxic versus oxic bottom waters. The latter are physically mixed by animals moving through the surface sediment (bioturbation) and ventilated by burrowing, tube-dwelling organisms (bioirrigation). The model is constrained using an empirical database including burial ratios of Corg with respect to organic P (Corg:Porg) and total reactive P (Corg:Preac), burial efficiencies of Corg and Porg, and inorganic carbon-to-phosphorus regeneration ratios. If Porg is preferentially mineralized relative to Corg during aerobic respiration, as many previous studies suggest, then the simulated Porg pool is found to be completely depleted. A modified model that incorporates the redox-dependent microbial synthesis of polyphosphates and Porg (termed the microbial P pump) allows preferential mineralization of the bulk Porg pool relative to Corg during both aerobic and anaerobic respiration and is consistent with the database. Results with this model show that P burial is strongly enhanced in sediments hosting fauna. Animals mix highly labile Porg away from the aerobic sediment layers where mineralization rates are highest, thereby mitigating diffusive PO43- fluxes to the bottom water. They also expand the redox niche where microbial P uptake occurs. The model was applied to a hypothetical shelf setting in the early Paleozoic; a time of the first radiation of benthic fauna. Results show that even shallow bioturbation at that time may have had a significant impact on P burial. Our model provides support for a recent study that proposed that faunal radiation in ocean sediments led to enhanced P burial and, possibly, a stabilization of atmospheric O2 levels. The results also help to explain Corg:Porg ratios in the geological record and the persistence of Porg in ancient marine sediments.

  1. Phylogenetic analysis of the bacterial communities in marine sediments.

    PubMed Central

    Gray, J P; Herwig, R P

    1996-01-01

    For the phylogenetic analysis of microbial communities present in environmental samples microbial DNA can be extracted from the sample, 16S rDNA can be amplified with suitable primers and the PCR, and clonal libraries can be constructed. We report a protocol that can be used for efficient cell lysis and recovery of DNA from marine sediments. Key steps in this procedure include the use of a bead mill homogenizer for matrix disruption and uniform cell lysis and then purification of the released DNA by agarose gel electrophoresis. For sediments collected from two sites in Puget Sound, over 96% of the cells present were lysed. Our method yields high-molecular-weight DNA that is suitable for molecular studies, including amplification of 16S rRNA genes. The DNA yield was 47 micrograms per g (dry weight) for sediments collected from creosote-contaminated Eagle Harbor, Wash. Primers were selected for the PCR amplification of (eu)bacterial 16S rDNA that contained linkers with unique 8-base restriction sites for directional cloning. Examination of 22 16S rDNA clones showed that the surficial sediments in Eagle Harbor contained a phylogenetically diverse population of organisms from the Bacteria domain (G. J. Olsen, C. R. Woese, and R. Overbeek, J. Bacteriol. 176:1-6, 1994) with members of six major lineages represented: alpha, delta, and gamma Proteobacteria; the gram-positive high G+C content subdivision; clostridia and related organisms; and planctomyces and related organisms. None of the clones were identical to any representatives in the Ribosomal Database Project small subunit RNA database. The analysis of clonal representives in the first report using molecular techniques to determine the phylogenetic composition of the (eu)bacterial community present in coastal marine sediments. PMID:8899989

  2. Archaeal Diversity in Marine Sediments in the South China Sea

    NASA Astrophysics Data System (ADS)

    Wei, Y.; Wang, P.; Liu, Z.; Zhao, M.; Zhang, C.

    2010-12-01

    Archaea are widespread and play an important role in the global carbon and nitrogen cycles. However, we still have limited knowledge about archaeal diversity and their function in the natural environment. The purpose of this study was to examine the diversity, distribution and abundance of archaea associated with methane-rich sediments in the South China Sea. A gravity core (HQ08-48PC, 714 cm) was collected from the northern South China Sea and aseptically sliced into 20-cm sections. Samples from near the surface (0-20 cm), middle (350-370 cm) and bottom (630-650 cm) of the core were used for the construction of archaeal clone libraries. Chemical analysis indicated that the core was rich in methane (13.6-58.8 ppm) and had low TOC/TN ratios (< 8), which indicated a marine source of the organic matter. Total amino acids ranged between 2.72 µmol/g and 8.75 µmol/g. Phylogenetic analysis revealed that archaeal community structures were dramatically different and Crenarchaeaota dominates over Euryarchaeota among the surface, middle and bottom sediments of the core. The dominant archaeal groups were MGI (40%), MBGB (27%) and MCG (9%) in the surface sediment, MCG (35%), MBGD (20%) and MCG (20%) in the middle sediment, and MCG (52%) and MBGD (33%) in the bottom sediment. MCG and MBGD increased in phytotypes with increasing depth of the core, indicating their potential importance in deeper marine subsurface. The archaeal lipids (GDGTs) showed an increase in abundance with depth. Calculations of TEX86 based on certain types of GDGTs suggested a dramatic change in sea surface temperature (SST) that might correspond to the transition from the last glacial maximum (LGM) to post-glacial period. This study will enhance our understanding of archaeal diversity and function as well as their paleoclimate applications in the South China Sea.

  3. Bacterial activities driving arsenic speciation and solubility in marine sediments

    NASA Astrophysics Data System (ADS)

    Battaglia-Brunet, F.; Seby, F.; Crouzet, C.; Joulian, C.; Mamindy-Pajany, Y.; Guezennec, A. G.; Hurel, C.; Marmier, N.; Bataillard, P.

    2012-04-01

    Harbour and marina sediments represent particular environments, with high concentrations in organic carbon and pollutants. Over 50 million m3 of marine sediments are dredged every year in French maritime and commercial ports, to maintain the water depth suitable for navigation, and the most part of them is discharged in deeper sea zones. The present study aimed to elucidate, using a range of complementary approaches, the influence of bacterial activity on arsenic speciation and mobility in marina sediments. Two sites were considered: L'Estaque, impacted by metallurgical activities and by the commercial port of Marseille, and St-Mandrier, less polluted, affected by classical chemical pollutants associated to professional and recreational boating. Arsenic concentration was noticeably higher in l'Estaque sediment (200-350 mg/kg) than in St-Mandrier sediment (15-50 mg/kg). In the solid phases, As(III) was the dominant species in L'Estaque sediment, whereas As(V) was the main form in St Mandrier sediment. At both sites, arsenic was the major trace element detected in interstitial water. Free sulfide and thio-arsenic complexes were detected in the interstitial water of l'Estaque sediment, suggesting a role of sulfate-reduction bacterial activity on arsenic solubility. Anaerobic microcosm experiments confirmed this hypothesis, as stimulation of sulfate-reduction induced a dramatic increase of arsenic concentration in the liquid phase, linked to the formation of soluble thio-arsenic complexes. Nevertheless, microcosms performed in aerobic conditions showed that bacterial activity globally decreased the transfer of arsenic from the sediment toward the overlying water. A red-brown fine layer developed at the sediment-water interface. Altogether, these results suggest that the sediment-water interface zone and the close transition area between aerobic and anaerobic conditions host intense biogeochemical reactions involving As, Fe and S species. These reactions most probably

  4. Toxicity and photoactivation of PAH mixtures in marine sediment

    SciTech Connect

    Swartz, R.; Ferraro, S.; Lamberson, J.; Cole, F.; Ozretich, R.; Boese, B.; Schults, D.; Behrenfeld, M.; Ankley, G.

    1995-12-31

    The toxicity and toxicological photoactivation of mixtures of sediment-associated fluoranthene, phenanthrene, pyrene, and acenaphthene were determined using standard 10 d sediment toxicity tests with the marine amphipod, Rhepoxynius abronius. The four PAHs were spiked into sediment in a concentration series of either single compounds or an equitoxic mixture. Spiked sediment was stored at 4 C for 28 d before testing. Toxicity tests were conducted under fluorescent lighting. Survivors after 10 d in PAH-contaminated sediment were exposed for 1 h to UV light in the absence of sediment and then tested for their ability to bury in clean sediment. The 10 d LC50s for single PAHs were 3.3, 2.2, 2.8, and 2.3 mg/g oc for fluoranthene, phenanthrene, pyrene, and acenaphthene, respectively. These LC50s were used to calculate the sum of toxic units ({Sigma}TU) of the four PAHs in the equitoxic mixture treatments. The {Sigma}TU LC50 was then calculated for the mixture treatments. If the toxicological interaction of the four PAHs in the mixture was additive, the {Sigma}TU LC50 should equal 1.0. The observed {Sigma}TU LC50 in the mixture was 1.55, indicating the interaction was slightly less than additive. UV enhancement of toxic effects of individual PAHs was correctly predicted by photophysical properties, i.e. pyrene and fluoranthene were photoactivated and phenanthrene and acenaphthene were not. UV effects in the mixture of four PAHs can be explained by the photoactivation of pyrene and fluoranthene alone.

  5. Marine fungi isolated from Chilean fjord sediments can degrade oxytetracycline.

    PubMed

    Ahumada-Rudolph, R; Novoa, V; Sáez, K; Martínez, M; Rudolph, A; Torres-Diaz, C; Becerra, J

    2016-08-01

    Salmon farming is the main economic activity in the fjords area of Southern Chile. This activity requires the use of antibiotics, such as oxytetracycline, for the control and prevention of diseases, which have a negative impact on the environment. We analyzed the abilities of endemic marine fungi to biodegrade oxytetracycline, an antibiotic used extensively in fish farming. We isolated marine fungi strains from sediment samples obtained from an area of fish farming activity. The five isolated strains showed an activity on oxytetracycline and were identified as Trichoderma harzianum, Trichoderma deliquescens, Penicillium crustosum, Rhodotorula mucilaginosa, and Talaromyces atroroseus by a scanning electron microscopy and characterized by molecular techniques. Results showed significant degradation in the concentration of oxytetracycline at the first 2 days of treatment for all strains analyzed. At 21 days of treatment, the concentration of oxytetracycline was decreased 92 % by T. harzianum, 85 % by T. deliquescens, 83 % by P. crustosum, 73 % by R. mucilaginosa, and 72 % by T. atroroseus, all of which were significantly higher than the controls. Given these results, we propose that fungal strains isolated from marine sediments may be useful tools for biodegradation of antibiotics, such as oxytetracycline, in the salmon industry. PMID:27418075

  6. Marine fungi isolated from Chilean fjord sediments can degrade oxytetracycline.

    PubMed

    Ahumada-Rudolph, R; Novoa, V; Sáez, K; Martínez, M; Rudolph, A; Torres-Diaz, C; Becerra, J

    2016-08-01

    Salmon farming is the main economic activity in the fjords area of Southern Chile. This activity requires the use of antibiotics, such as oxytetracycline, for the control and prevention of diseases, which have a negative impact on the environment. We analyzed the abilities of endemic marine fungi to biodegrade oxytetracycline, an antibiotic used extensively in fish farming. We isolated marine fungi strains from sediment samples obtained from an area of fish farming activity. The five isolated strains showed an activity on oxytetracycline and were identified as Trichoderma harzianum, Trichoderma deliquescens, Penicillium crustosum, Rhodotorula mucilaginosa, and Talaromyces atroroseus by a scanning electron microscopy and characterized by molecular techniques. Results showed significant degradation in the concentration of oxytetracycline at the first 2 days of treatment for all strains analyzed. At 21 days of treatment, the concentration of oxytetracycline was decreased 92 % by T. harzianum, 85 % by T. deliquescens, 83 % by P. crustosum, 73 % by R. mucilaginosa, and 72 % by T. atroroseus, all of which were significantly higher than the controls. Given these results, we propose that fungal strains isolated from marine sediments may be useful tools for biodegradation of antibiotics, such as oxytetracycline, in the salmon industry.

  7. Volatile fatty acids as substrates for iron and sulfate reduction in Arctic marine sediments, Svalbard

    NASA Astrophysics Data System (ADS)

    Finke, N.; Vandieken, V.; Jorgensen, B. B.

    2006-12-01

    Anaerobic degradation of complex organic material in aquatic systems is a multi-step process. The metabolic products of fermentative bacteria serve as electron donors for the terminal oxidizing bacteria. In marine sediments, iron reduction and sulfate reduction are generally the most important terminal oxidation processes in the upper anoxic zone [1]. Microorganisms that reduce iron and sulfate may use a broad range of electron donors, yet the list of potential substrates provides little information about the substrates used in situ by these organisms. Investigations on the electron donors for sulfate reducers in marine sediments have shown that volatile fatty acids (VFA), and in particular acetate, together with hydrogen are the major substrates (e.g. [2-4]). Similar investigations for iron reduction or simultaneous iron and sulfate reduction are lacking for marine sediments. Furthermore, most of these studies were made in temperate sediments and little is known about the substrates for sulfate reducers in permanently cold sediments, which account for >90% of the ocean floor [5]. We investigated the relative contributions of iron reduction and sulfate reduction to the terminal oxidation of organic carbon and the importance of acetate, lactate, propionate, and isobutyrate as electron donors for iron and sulfate reduction in permanently cold, Arctic sediments from Svalbard. In the surface layer (0-2 cm) sulfate reduction accounted for 2/3 of the organic carbon oxidation (determined as DIC production), the remaining 1/3 were attributed to iron reduction. In the 5-9 cm layer sulfate reduction was the sole important terminal oxidation step. The contribution of acetate to terminal oxidation was determined by radiotracer incubation as well as from the accumulation after the inhibition of sulfate reduction by selenate. The rates determined with the two methods varied by less than 20%. Acetate turnover, determined with the tracer incubations, accounted for 10 and 40% of

  8. MARINE SEDIMENT TOXICITY IDNETIFICATION EVALUATION METHODS FOR THE ANIONIC METALS ARSENIC AND CHROMIUM

    EPA Science Inventory

    Marine sediments accumulate a diversity of contaminants and, in some cases, demonstrate toxicity because of this contamination. Toxicity Identification Evaluation (TIE) methods provide tools for identifying the toxic chemicals causing sediment toxicity. Currently, whole sedimen...

  9. IMPORTANCE OF INTERSTITIAL, OVERLYING WATER AND WHOLE SEDIMENT EXPOSURES TO BIOACCUMUALTION BY MARINE BIVALVES

    EPA Science Inventory

    During the performance of contaminated sediment studies using nonpolar pollutants, like polyclorinated biphenyls (PCBs), with marine organisms, the routes of exposure can include whole sediment, overlying waters and interstitial waters (assuming no feeding). These routes can be f...

  10. PHOTOACTIVATION AND TOXICITY OF MIXTURES OF POLYCYCLIC AROMATIC HYDROCARBON COMPOUNDS IN MARINE SEDIMENT

    EPA Science Inventory

    The direct toxicity and photoinduced toxicity of sediment-associated acenaphthene, phenanthrene, fluoranthene, and pyrene were determined for the marine amphipod Rhepoxynius abronius. The four polycyclic aromatic hydrocarbons (PAHs) were spiked into sediment in a concentration se...

  11. Contaminated marine sediments: Water column and interstitial toxic effects

    SciTech Connect

    Burgess, R.M.; Schweitzer, K.A.; McKinney, R.A.; Phelps, D.K.

    1993-01-01

    The toxicity that contaminated sediments may introduce into the water column has not been measured extensively. In order to quantify this potential toxicity, the seawater overlying two uncontaminated and three contaminated marine sediments was evaluated in the laboratory with the sea urchin Arbacia punctulata fertilization test. Concentrations of polychlorinated biphenyls (PCBs) and copper, as representative contaminants, were also measured. To characterize sources of toxicity, samples were chemically manipulated using reversed-phase chromatography, cation exchange, and chelation. Water column toxicity and contaminant concentrations were higher in the suspended exposures than in bedded exposures. Interstitial water toxicity and contaminant concentrations were generally greater than either bedded or suspended exposures. Chemical manipulation indicated that the observed toxicity in water column exposures was probably caused by metallic and/or nonionic organic contaminants. Conversely, manipulation of interstitial waters did not result in significantly reduced toxicity, suggesting that other toxicants such as ammonia and hydrogen sulfide may be active.

  12. Contaminated marine sediments: Water column and interstitial toxic effects

    SciTech Connect

    Burgess, R.M.; McKinney, R.A. ); Schweitzer, K.A. ); Phelps, D.K. )

    1993-01-01

    The toxicity that contaminated sediments may introduce into the water column has not been measured extensively. In order to quantify this potential toxicity, the seawater overlying two uncontaminated and three contaminated marine sediments was evaluated in the laboratory with the sea urchin Arbacia punctulata fertilization test. Concentration of polychlorinated biphenyls (PCBs) and copper, as representative contaminants, were also measured. To characterize sources of toxicity, samples were chemically manipulated using reversed-phase chromatography, cation exchange, and chelation. Water column toxicity and contaminant concentrations were higher in the suspended exposures than in bedded exposures. Interstitial water toxicity and contaminant concentrations were generally greater than either bedded or suspended exposures. Chemical manipulation indicated that the observed toxicity in water column exposures was probably caused by metallic and/or nonionic organic contaminants. Conversely, manipulation of interstitial water did not result in significantly reduced toxicity, suggesting that other toxicants such as ammonia and hydrogen sulfide may be active.

  13. Factors influencing organic carbon preservation in marine sediments

    NASA Technical Reports Server (NTRS)

    Canfield, D. E.

    1994-01-01

    The organic matter that escapes decomposition is buried and preserved in marine sediments, with much debate as to whether the amount depends on bottom-water O2 concentration. One group argues that decomposition is more efficient with O2, and hence, organic carbon will be preferentially oxidized in its presence, and preserved in its absence. Another group argues that the kinetics of organic matter decomposition are similar in the presence and absence of O2, and there should be no influence of O2 on preservation. A compilation of carbon preservation shows that both groups are right, depending on the circumstances of deposition. At high rates of deposition, such as near continental margins, little difference in preservation is found with varying bottom-water O2. It is important that most carbon in these sediments decomposes by anaerobic pathways regardless of bottom-water O2. Hence, little influence of bottom-water O2 on preservation would, in fact, be expected. As sedimentation rate drops, sediments deposited under oxygenated bottom water become progressively more aerobic, while euxinic sediments remain anaerobic. Under these circumstances, the relative efficiencies of aerobic and anaerobic decomposition could affect preservation. Indeed, enhanced preservation is observed in low-O2 and euxinic environments. To explore in detail the factors contributing to this enhanced carbon preservation, aspects of the biochemistries of the aerobic and anaerobic process are reviewed. Other potential influences on preservation are also explored. Finally, a new model for organic carbon decomposition, the "pseudo-G" model, is developed. This model couples the degradation of refractory organic matter to the overall metabolic activity of the sediment, and has consequences for carbon preservation due to the mixing together of labile and refractory organic matter by bioturbation.

  14. Trace metal seasonal variations in Texas marine sediments

    USGS Publications Warehouse

    Holmes, C.W.

    1986-01-01

    Trace elements in coastal environments are derived from three major sources: (1) the bordering watershed; (2) the offshore marine environment; and (3) industrial and/or urban effluent. The site of deposition, however, is controlled by physical and chemical processes in the coastal zone. In many cases, these processes are controlled by climate and can vary seasonally. In the harbor at Corpus Christi, Texas, the summer climate creates an oxygen-poor environment in the water column near the sediment-water interface. This causes chalcophilic metals to precipitate from the water, resulting in high concentrations in the sediments near the source. During the winter, turbulence created by strong winds causes the entire water mass to become aerated and oxidizing, and remobilization of some metals results. In addition, this turbulence accelerates circulation which transports the metal-enriched waters from the harbor. On the outer continental shelf of south Texas, the infaunal activity varies seasonally with bottom water temperatures. As this infaunal activity has an effect on the chemical environment within the sediment near the sediment-water interface, the observed trace metal content at the interface also appears to change with the seasons. ?? 1986.

  15. Idealized model of nitrogen recycling in marine sediments

    SciTech Connect

    Billen, G.

    1982-04-01

    A model of the interdependent processes involved in nitrogen mineralization in marine sediments is presented, based on data collected in the sandy sediments of the North Sea. It relates the flux of organic material deposited in the sediments to the release of dissolved nitrogen to the overlying water, given the mixing conditions undergone by the solid and interstitial phases of the sediment under the action of physical or biological processes. Although idealized, the model can be useful in predicting the trends of variation in the relative importance of ammonification, nitrification, and denitrification, as a result of variations in the organic matter input to the bottom. It shows that, at low input of organic matter, most nitrogen release occurs as nitrate, whereas, at higher input, ammonium release prevails. Denitrification reaches a plateau above a certain input of organic material. It can involve an appreciable proportion (more than about 30 percent of the flux) of remineralized nitrogen only at high organic input and when a high nitrate concentration exists in the overlying water.

  16. 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.

  17. Magnet-Facilitated Selection of Electrogenic Bacteria from Marine Sediment

    PubMed Central

    Kiseleva, Larisa; Briliute, Justina; Khilyas, Irina V.; Simpson, David J. W.; Fedorovich, Viacheslav; Cohen, M.; Goryanin, Igor

    2015-01-01

    Some bacteria can carry out anaerobic respiration by depositing electrons on external materials, such as electrodes, thereby creating an electrical current. Into the anode chamber of microbial fuel cells (MFCs) having abiotic air-cathodes we inoculated microorganisms cultured from a magnetic particle-enriched portion of a marine tidal sediment, reasoning that since some external electron acceptors are ferromagnetic, electrogenic bacteria should be found in their vicinity. Two MFCs, one inoculated with a mixed bacterial culture and the other with an axenic culture of a helical bacterium isolated from the magnetic particle enrichment, termed strain HJ, were operated for 65 d. Both MFCs produced power, with production from the mixed culture MFC exceeding that of strain HJ. Strain HJ was identified as a Thalassospira sp. by transmission electron microscopic analysis and 16S rRNA gene comparisons. An MFC inoculated with strain HJ and operated in open circuit produced 47% and 57% of the maximal power produced from MFCs inoculated with the known electrogen Geobacter daltonii and the magnetotactic bacterium Desulfamplus magnetomortis, respectively. Further investigation will be needed to determine whether bacterial populations associated with magnetic particles within marine sediments are enriched for electrogens. PMID:26504814

  18. Magnet-Facilitated Selection of Electrogenic Bacteria from Marine Sediment.

    PubMed

    Kiseleva, Larisa; Briliute, Justina; Khilyas, Irina V; Simpson, David J W; Fedorovich, Viacheslav; Cohen, M; Goryanin, Igor

    2015-01-01

    Some bacteria can carry out anaerobic respiration by depositing electrons on external materials, such as electrodes, thereby creating an electrical current. Into the anode chamber of microbial fuel cells (MFCs) having abiotic air-cathodes we inoculated microorganisms cultured from a magnetic particle-enriched portion of a marine tidal sediment, reasoning that since some external electron acceptors are ferromagnetic, electrogenic bacteria should be found in their vicinity. Two MFCs, one inoculated with a mixed bacterial culture and the other with an axenic culture of a helical bacterium isolated from the magnetic particle enrichment, termed strain HJ, were operated for 65 d. Both MFCs produced power, with production from the mixed culture MFC exceeding that of strain HJ. Strain HJ was identified as a Thalassospira sp. by transmission electron microscopic analysis and 16S rRNA gene comparisons. An MFC inoculated with strain HJ and operated in open circuit produced 47% and 57% of the maximal power produced from MFCs inoculated with the known electrogen Geobacter daltonii and the magnetotactic bacterium Desulfamplus magnetomortis, respectively. Further investigation will be needed to determine whether bacterial populations associated with magnetic particles within marine sediments are enriched for electrogens. PMID:26504814

  19. Pyrite framboid size distribution as a record for relative variations in sedimentation rate: An example on the Toarcian Oceanic Anoxic Event in Southiberian Palaeomargin

    NASA Astrophysics Data System (ADS)

    Gallego-Torres, David; Reolid, Matías; Nieto-Moreno, Vanesa; Martínez-Casado, Francisco Javier

    2015-12-01

    The Early Toarcian Oceanic Anoxic Event (T-OAE) represents one of the major alterations of the carbon cycle of the Mesozoic period. Despite being globally recognized, and particularly represented within the Tethys realm, its expression in the sedimentary record is highly variable depending on the studied section, which suggests local environmental factors exert a major control on the resulting lithological appearance of the event. We investigated the Fuente Vidriera section, in the eastern External Subbetic of the Betic Cordillera (Spain), where the Lower Jurassic is represented by alternate layers of marls and marly limestones, and the T-OAE is identified by a major δ13C excursion, micropalaeontological, ichnofacies and geochemical evidences. For this study, we analyzed pyrite framboid size distribution of the sedimentary sequence in Fuente Vidriera. The outcome, according to previous studies on pyrite framboid distribution, is contradictory when compared to all other evidences, suggesting oxygen depletion during the T-OAE. The results have been reinterpreted in the light of Crystal Size Distribution Theory and we conclude that not only growth time but also geochemical environment controls pyrite formation. Since growth time is directly related to burial rates, this approach allows us to reconstruct relative variations of sedimentation rates during the Early Jurassic in this location. Based on the obtained results, we provide new evidences for wide-spread transgression during the Early Toarcian in the South Iberian palaeomargin, which induced low sedimentation rate and lower energetic conditions, as well as favored oxygen impoverished bottom waters.

  20. Role of methanogens and other bacteria in degradation of dimethyl sulfide and methanethiol in anoxic freshwater sediments

    SciTech Connect

    Lomans, B.P.; Op den Camp, H.J.M.; Pol, A.; Drift, C. van der; Vogels, G.D.

    1999-05-01

    The roles of several trophic groups of organisms (methanogens and sulfate- and nitrate-reducing bacteria) in the microbial degradation of methanethiol (MT) and dimethyl sulfide (DMS) were studied in freshwater sediments. The incubation of DMS- and MT-amended slurries revealed that methanogens are the dominant DMS and MT utilizers in sulfate-poor freshwater systems. In sediment slurries, which were depleted of sulfate, 75 {micro}mol of DMS was stoichiometrically converted into 112 {micro}mol of methane. The addition of methanol or MT to DMS-degrading slurries at concentrations similar to that of DMS reduced DMS degradation rates. This indicates that the methanogens in freshwater sediments, which degrade DMS, are also consumers of methanol and MT. To verify whether a competition between sulfate-reducing and methanogenic bacteria for DMS or MT takes place in sulfate-rich freshwater systems, the effects of sulfate and inhibitors, like bromoethanesulfonic acid, molybdate, and tungstate, on the degradation of MT and DMS were studied. The results for these sulfate-rich and sulfate-amended slurry incubations clearly demonstrated that besides methanogens, sulfate-reducing bacteria take part in MT and DMS degradation in freshwater sediments, provided that sulfate is available. The possible involvement of an interspecies hydrogen transfer in these processes is discussed. In general, the study provides evidence for methanogenesis as a major sink for MT and DMS in freshwater sediments.

  1. Influence of acid volatile sulfide and metal concentrations on metal bioavailability to marine invertebrates in contaminated sediments

    USGS Publications Warehouse

    Lee, B.-G.; Lee, J.-S.; Luoma, S.N.; Choi, H.J.; Koh, C.-H.

    2000-01-01

    An 18-day microcosm study was conducted to evaluate the influence of acid volatile sulfides (AVS) and metal additions on bioaccumulation from sediments of Cd, Ni, and Zn in two clams (Macoma balthica and Potamocorbula amurensis) and three marine polychaetes (Neanthes arenaceodentata, Heteromastus filiformis, and Spiophanes missionensis). Manipulation of AVS by oxidation of naturally anoxic sediments allowed use of metal concentrations typical of nature and evaluation of processes important to chronic metal exposure. A vertical sediment column similar to that often found in nature was used to facilitate realistic biological behavior. Results showed that AVS or porewater (PW) metals controlled bioaccumulation in only 2 of 15 metal-animal combinations. Bioaccumulation of all three metals by the bivalves was related significantly to metal concentrations extracted from sediments (SEM) but not to [SEM - AVS] or PW metals. SEM predominantly influenced bioaccumulation of Ni and Zn in N. arenaceodentata, but Cd bioaccumulation followed PW Cd concentrations. SEM controlled tissue concentrations of all three metals in H. filiformis and S. missionensis, with minor influences from metal-sulfide chemistry. Significant bioaccumulation occurred when SEM was only a small fraction of AVS in several treatments. Three factors appeared to contribute to the differences between these bioaccumulation results and the results from toxicity tests reported previously: differences in experimental design, dietary uptake, and biological attributes of the species, including mode and depth of feeding.An 18-day microcosm study was conducted to evaluate the influence of acid volatile sulfides (AVS) and metal additions on bioaccumulation from sediments of Cd, Ni, and Zn in two clams (Macoma balthica and Potamocorbula amurensis) and three marine polychaetes (Neanthes arenaceodentata, Heteromastus filiformis, and Spiophanes missionensis). Manipulation of AVS by oxidation of naturally anoxic sediments

  2. Effect of physical sediments reworking on hydrocarbon degradation and bacterial community structure in marine coastal sediments.

    PubMed

    Duran, Robert; Bonin, Patricia; Jezequel, Ronan; Dubosc, Karine; Gassie, Claire; Terrisse, Fanny; Abella, Justine; Cagnon, Christine; Militon, Cecile; Michotey, Valérie; Gilbert, Franck; Cuny, Philippe; Cravo-Laureau, Cristiana

    2015-10-01

    The present study aimed to examine whether the physical reworking of sediments by harrowing would be suitable for favouring the hydrocarbon degradation in coastal marine sediments. Mudflat sediments were maintained in mesocosms under conditions as closer as possible to those prevailing in natural environments with tidal cycles. Sediments were contaminated with Ural blend crude oil, and in half of them, harrowing treatment was applied in order to mimic physical reworking of surface sediments. Hydrocarbon distribution within the sediment and its removal was followed during 286 days. The harrowing treatment allowed hydrocarbon compounds to penetrate the first 6 cm of the sediments, and biodegradation indexes (such as n-C18/phytane) indicated that biodegradation started 90 days before that observed in untreated control mesocosms. However, the harrowing treatment had a severe impact on benthic organisms reducing drastically the macrofaunal abundance and diversity. In the harrowing-treated mesocosms, the bacterial abundance, determined by 16S rRNA gene Q-PCR, was slightly increased; and terminal restriction fragment length polymorphism (T-RFLP) analyses of 16S rRNA genes showed distinct and specific bacterial community structure. Co-occurrence network and canonical correspondence analyses (CCA) based on T-RFLP data indicated the main correlations between bacterial operational taxonomic units (OTUs) as well as the associations between OTUs and hydrocarbon compound contents further supported by clustered correlation (ClusCor) analysis. The analyses highlighted the OTUs constituting the network structural bases involved in hydrocarbon degradation. Negative correlations indicated the possible shifts in bacterial communities that occurred during the ecological succession.

  3. Effect of physical sediments reworking on hydrocarbon degradation and bacterial community structure in marine coastal sediments.

    PubMed

    Duran, Robert; Bonin, Patricia; Jezequel, Ronan; Dubosc, Karine; Gassie, Claire; Terrisse, Fanny; Abella, Justine; Cagnon, Christine; Militon, Cecile; Michotey, Valérie; Gilbert, Franck; Cuny, Philippe; Cravo-Laureau, Cristiana

    2015-10-01

    The present study aimed to examine whether the physical reworking of sediments by harrowing would be suitable for favouring the hydrocarbon degradation in coastal marine sediments. Mudflat sediments were maintained in mesocosms under conditions as closer as possible to those prevailing in natural environments with tidal cycles. Sediments were contaminated with Ural blend crude oil, and in half of them, harrowing treatment was applied in order to mimic physical reworking of surface sediments. Hydrocarbon distribution within the sediment and its removal was followed during 286 days. The harrowing treatment allowed hydrocarbon compounds to penetrate the first 6 cm of the sediments, and biodegradation indexes (such as n-C18/phytane) indicated that biodegradation started 90 days before that observed in untreated control mesocosms. However, the harrowing treatment had a severe impact on benthic organisms reducing drastically the macrofaunal abundance and diversity. In the harrowing-treated mesocosms, the bacterial abundance, determined by 16S rRNA gene Q-PCR, was slightly increased; and terminal restriction fragment length polymorphism (T-RFLP) analyses of 16S rRNA genes showed distinct and specific bacterial community structure. Co-occurrence network and canonical correspondence analyses (CCA) based on T-RFLP data indicated the main correlations between bacterial operational taxonomic units (OTUs) as well as the associations between OTUs and hydrocarbon compound contents further supported by clustered correlation (ClusCor) analysis. The analyses highlighted the OTUs constituting the network structural bases involved in hydrocarbon degradation. Negative correlations indicated the possible shifts in bacterial communities that occurred during the ecological succession. PMID:25847440

  4. Sulfonates: A novel class of organic sulfur compounds in marine sediments

    NASA Astrophysics Data System (ADS)

    Vairavamurthy, Appathurai; Zhou, Weiqing; Eglinton, Timothy; Manowitz, Bernard

    1994-11-01

    X-ray absorption near-edge structure spectroscopy (XANES) used to measure sulfur speciation in a variety of organic-rich marine sediments has established sulfonates as a novel and major component of sedimentary organic sulfur. The origins of sulfonates in sediments are not clear, although both biological and geochemical mechanisms are possible. The accumulation of oxidized sulfonate sulfur in reducing marine sediments was not known previously; hence, a new perspective in sulfur geochemistry is established. The biogeochemical implications of the presence of sulfonates in marine sediments are discussed.

  5. Terrestrial Sediment Delivery to Coastal and Marine Environments: US Virgin Islands

    NASA Astrophysics Data System (ADS)

    Larson, R. A.; Brooks, G. R.; Devine, B.; Wallace, L. E.; Holmes, C. W.; Schwing, P. T.

    2007-05-01

    Understanding terrestrial sediment dynamics in high-relief, tropical island settings, such as St. Thomas and St. John, USVI, has become a critical issue, as sediments are a potential threat to the health of down-slope environments. The primary depositional sinks of terrestrial sediments are 1) coastal buffer zones such as salt ponds, which trap sediments and keep them from being input into the marine environment, and 2) near-shore marine environments (coral reefs, seagrasses, algal flats etc.), many of which are adversely affected by terrestrial sedimentation. Land use change by anthropogenic activities has been shown to alter terrestrial sediment dynamics and greatly increase sediment delivery and accumulation rates in coastal and marine environments. Sediment cores collected in salt ponds and the near-shore marine environment were used to determine the sedimentology (texture and composition) and geochronology (using 14C, and 210Pb) prior to anthropogenic activities to define the "natural signal", or "baseline", as well as recent deviations from the "natural signal", which may be attributed to anthropogenic activities. Salt pond and marine sediments in watersheds without anthropogenic activities exhibit no deviations from the "natural signal" in sedimentology or accumulation rate. Salt pond and marine sediments in watersheds with anthropogenic activities contain a deviation from the "natural signal" manifested as an increase in accumulation rate within the last 100 yrs (most likely within the last 25-50 yrs) ranging from 3 -10 times greater than the "natural" accumulation rate. Sedimentologically, salt ponds reflect no recent change, where as marine sediments do show a recent deviation in sedimentology. This marine deviation is represented by an increase in organic content, a decrease in grain size, and a decrease in carbonate content (marine-derived) compared to the "natural signal". This change reflects an increase in terrestrial (non- carbonate, finer

  6. Evaluation of marine sediments as microbial sources for methane production from brown algae under high salinity.

    PubMed

    Miura, Toyokazu; Kita, Akihisa; Okamura, Yoshiko; Aki, Tsunehiro; Matsumura, Yukihiko; Tajima, Takahisa; Kato, Junichi; Nakashimada, Yutaka

    2014-10-01

    Various marine sediments were evaluated as promising microbial sources for methane fermentation of Saccharina japonica, a brown alga, at seawater salinity. All marine sediments tested produced mainly acetate among volatile fatty acids. One marine sediment completely converted the produced volatile fatty acids to methane in a short period. Archaeal community analysis revealed that acetoclastic methanogens belonging to the Methanosarcina genus dominated after cultivation. Measurement of the specific conversion rate at each step of methane production under saline conditions demonstrated that the marine sediments had higher conversion rates of butyrate and acetate than mesophilic methanogenic granules. These results clearly show that marine sediments can be used as microbial sources for methane production from algae under high-salt conditions without dilution.

  7. Estimating rates of authigenic carbonate precipitation in modern marine sediments

    NASA Astrophysics Data System (ADS)

    Mitnick, E. H.; Lammers, L. N.; DePaolo, D. J.

    2015-12-01

    The formation of authigenic carbonate (AC) in marine sediments provides a plausible explanation for large, long-lasting marine δ13C excursions that does not require extreme swings in atmospheric O2 or CO2. AC precipitation during diagenesis is driven by alkalinity production during anaerobic organic matter oxidation and is coupled to sulfate reduction. To evaluate the extent to which this process contributes to global carbon cycling, we need to relate AC production to the geochemical and geomicrobiological processes and ocean chemical conditions that control it. We present a method to estimate modern rates of AC precipitation using an inversion approach based on the diffusion-advection-reaction equation and sediment pore fluid chemistry profiles as a function of depth. SEM images and semi-quantitative elemental map analyses provide further constraints. Our initial focus is on ODP sites 807 and 1082. We sum the diffusive, advective, and reactive terms that describe changes in pore fluid Ca and Mg concentrations due to precipitation of secondary carbonate. We calculate the advective and diffusive terms from the first and second derivatives of the Ca and Mg pore fluid concentrations using a spline fit to the data. Assuming steady-state behavior we derive net AC precipitation rates of up to 8 x 10-4 mmol m-2 y-1 for Site 807 and 0.6 mmol m-2 y-1 for Site 1082. Site 1082 sediments contain pyrite, which increases in amount down-section towards the estimated peak carbonate precipitation rate, consistent with sulfate-reduction-induced AC precipitation. However, the presence of gypsum and barite throughout the sediment column implies incomplete sulfate reduction and merits further investigation of the biogeochemical reactions controlling authigenesis. Further adjustments to our method could account for the small but non-negligible fraction of groundmass with a CaSO4 signature. Our estimates demonstrate that AC formation may represent a sizeable flux in the modern global

  8. Evidence for Microbial Fe(III) Reduction in Anoxic, Mining-Impacted Lake Sediments (Lake Coeur d'Alene, Idaho)

    PubMed Central

    Cummings, David E.; March, Anthony W.; Bostick, Benjamin; Spring, Stefan; Caccavo, Frank; Fendorf, Scott; Rosenzweig, R. Frank

    2000-01-01

    Mining-impacted sediments of Lake Coeur d'Alene, Idaho, contain more than 10% metals on a dry weight basis, approximately 80% of which is iron. Since iron (hydr)oxides adsorb toxic, ore-associated elements, such as arsenic, iron (hydr)oxide reduction may in part control the mobility and bioavailability of these elements. Geochemical and microbiological data were collected to examine the ecological role of dissimilatory Fe(III)-reducing bacteria in this habitat. The concentration of mild-acid-extractable Fe(II) increased with sediment depth up to 50 g kg−1, suggesting that iron reduction has occurred recently. The maximum concentrations of dissolved Fe(II) in interstitial water (41 mg liter−1) occurred 10 to 15 cm beneath the sediment-water interface, suggesting that sulfidogenesis may not be the predominant terminal electron-accepting process in this environment and that dissolved Fe(II) arises from biological reductive dissolution of iron (hydr)oxides. The concentration of sedimentary magnetite (Fe3O4), a common product of bacterial Fe(III) hydroxide reduction, was as much as 15.5 g kg−1. Most-probable-number enrichment cultures revealed that the mean density of Fe(III)-reducing bacteria was 8.3 × 105 cells g (dry weight) of sediment−1. Two new strains of dissimilatory Fe(III)-reducing bacteria were isolated from surface sediments. Collectively, the results of this study support the hypothesis that dissimilatory reduction of iron has been and continues to be an important biogeochemical process in the environment examined. PMID:10618217

  9. Influence of pH on terminal carbon metabolism in anoxic sediments from a mildly acidic lake

    SciTech Connect

    Phelps, T.J.; Zeikus, J.G.

    1984-12-01

    The carbon and electron flow pathways and the bacterial populations responsible for transformation of H/sub 2/-CO/sub 2/, formate, methanol, methylamine, acetate, glycine, ethanol, and lactate were examined in sediments collected from Knaack Lake, Wisconsin. The sediments were 60% organic matter (pH 6.2) and did not display detectable sulfate-reducing activity, but they contained the following average concentration (in micromoles per liter of sediment) of metabolites and end products: sulfide, 10; methane, 1540; CO/sub 2/, 3950; formate, 25; acetate, 157; ethanol, 174; and lactate, 138. Methane was produced predominately from acetate, and only 4% of the total CH/sub 4/ was derived from CO/sub 2/. Methanogenesis was limited by low environmental temperature and sulfide levels and more importantly by low pH. Increasing in vitro pH to neutral values enhanced total methane production rates and the percentage of CO/sub 2/ transformed to methane but did not alter the amount of /sup 14/CO/sub 2/ produced from (2-/sup 14/C)acetate (approx. 24%). Analysis of both carbon transformation parameters with /sup 14/C-labeled tracers and bacterial trophic group enumerations indicated that methanogenesis from acetate and both heterolactic- and acetic acid-producing fermentations were important to the anaerobic digestion process.

  10. The “Oil-Spill Snorkel”: an innovative bioelectrochemical approach to accelerate hydrocarbons biodegradation in marine sediments

    PubMed Central

    Cruz Viggi, Carolina; Presta, Enrica; Bellagamba, Marco; Kaciulis, Saulius; Balijepalli, Santosh K.; Zanaroli, Giulio; Petrangeli Papini, Marco; Rossetti, Simona; Aulenta, Federico

    2015-01-01

    This study presents the proof-of-concept of the “Oil-Spill Snorkel”: a novel bioelectrochemical approach to stimulate the oxidative biodegradation of petroleum hydrocarbons in sediments. The “Oil-Spill Snorkel” consists of a single conductive material (the snorkel) positioned suitably to create an electrochemical connection between the anoxic zone (the contaminated sediment) and the oxic zone (the overlying O2-containing water). The segment of the electrode buried within the sediment plays a role of anode, accepting electrons deriving from the oxidation of contaminants. Electrons flow through the snorkel up to the part exposed to the aerobic environment (the cathode), where they reduce oxygen to form water. Here we report the results of lab-scale microcosms setup with marine sediments and spiked with crude oil. Microcosms containing one or three graphite snorkels and controls (snorkel-free and autoclaved) were monitored for over 400 days. Collectively, the results of this study confirmed that the snorkels accelerate oxidative reactions taking place within the sediment, as documented by a significant 1.7-fold increase (p = 0.023, two-tailed t-test) in the cumulative oxygen uptake and 1.4-fold increase (p = 0.040) in the cumulative CO2 evolution in the microcosms containing three snorkels compared to snorkel-free controls. Accordingly, the initial rate of total petroleum hydrocarbons (TPH) degradation was also substantially enhanced. Indeed, while after 200 days of incubation a negligible degradation of TPH was noticed in snorkel-free controls, a significant reduction of 12 ± 1% (p = 0.004) and 21 ± 1% (p = 0.001) was observed in microcosms containing one and three snorkels, respectively. Although, the “Oil-Spill Snorkel” potentially represents a groundbreaking alternative to more expensive remediation options, further research efforts are needed to clarify factors and conditions affecting the snorkel-driven biodegradation processes and to identify

  11. Sorption kinetics of TNT and RDX in anaerobic freshwater and marine sediments: Batch studies.

    PubMed

    Ariyarathna, Thivanka; Vlahos, Penny; Tobias, Craig; Smith, Richard

    2016-01-01

    Examination of the partitioning of explosives onto sediment in marine environments is critical to predict the toxicological impacts of worldwide explosive-contaminated sites adjacent to estuaries, wetlands, and the coastal ocean. Marine sediments have been identified as sites of enhanced munitions removal, yet most studies addressing these interactions focus on soils and freshwater sediments. The present study measured the kinetics of 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) sorption onto 2 marine sediments of varying grain sizes (silt vs sand) and organic carbon (OC) content. Abiotic sediment sorption tests were performed at 23 °C, 15 °C, and 4 °C by spiking TNT and RDX solutions directly into anaerobic sediment slurries. Marine sediments showed significantly higher compound uptake rates (0.30-0.80 h(-1) ) than freshwater silt (0.0046-0.0065 h(-1) ) for both compounds, probably because of lower compound solubilities and a higher pH in marine systems. Equilibrium partition constants are on the same order of magnitude for marine silt (1.1-2.0 L kg(-1) sediment) and freshwater silt (1.4-3.1 L kg(-1) sediment) but lower for marine sand (0.72-0.92 L kg(-1) sediment). Total organic carbon content in marine sediments varied linearly with equilibrium partition constants for TNT and was moderately linear for RDX. Uptake rates and equilibrium constants of explosives are inversely correlated to temperature regardless of sediment type because of kinetic barriers associated with low temperatures.

  12. Relative role of pore water versus ingested sediment in bioavailability of organic contaminants in marine sediments

    SciTech Connect

    Forbes, T.L.; Hansen, R.; Kure, L.K.; Forbes, V.E.; Giessing, A. |

    1998-12-01

    Experimental data for fluoranthene and feeding selectivity in combination with reaction-diffusion modeling suggest that ingestion of contaminated sediment may often be the dominant uptake pathway for deposit-feeding invertebrates in sediments. A dietary absorption efficiency of 56% and accompanying forage ratio of 2.4 were measured using natural sediment that had been dual-labeled ({sup 14}C:{sup 51}Cr) with fluoranthene and fed to the marine deposit-feeding polychaete Capitella species I. Only 3 to 4% of the total absorption could be accounted for by desorption during gut passage. These data were then used as input into a reaction-diffusion model to calculate the importance of uptake from ingested sediment relative to pore-water exposure. The calculations predict a fluoranthene dietary uptake flux that is 20 to 30 times greater than that due to pore water. Factors that act to modify or control the formation of local chemical gradients, boundary layers, or dietary absorption rates including particle selection or burrow construction will be important in determining the relative importance of potential exposure pathways. From a chemical perspective, the kinetics of the adsorption and desorption process are especially important as they will strongly influence the boundary layer immediately surrounding burrowing animals or irrigated tubes. The most important biological factors likely include irrigation behavior and burrow density and size.

  13. Failure of Marine Sediments due to Gas Hydrate Dissociation

    NASA Astrophysics Data System (ADS)

    Germanovich, L.; Xu, W.

    2004-12-01

    Methane gas hydrate (MGH) dissociation in the pore space of marine sediments may be caused by various natural and human-induced processes including sea level decrease, tectonic uplift of continental margins, global warming, and petroleum operations. While these processes generally have different spatial and temporal scales, they result in MGH dissociation, and the released gas and water tend to expand. This may change the pore pressure in the sediments, affecting their mechanical state and failure processes. If the pressure does not change, the hydrate dissociation may still affect the sediment properties by perturbing particle cementation and by introducing phase interfaces (e.g., capillary menisci). In this work, the pressure change has been calculated by coupling the dissociation rate with fluid flow in the sediments based on thermodynamic considerations. The common seafloor failure, submarine landslides, can reach a length of ˜100 km, with a length-to-thickness ratio as large as ˜1000. It is often assumed that the Storegga Slides were caused by earthquakes that instantaneously created a shallow discontinuity ( ˜100 m below the seafloor) along the entire slide length of ˜100 km. Instead, Puzrin and Germanovich [2004] reasoned that the MGH dissociation may have resulted in an initial flaw at the scale of only ˜1 km. They explained the landslide evolution in submarine slopes by the mechanism of catastrophic shear band propagation of this flaw. Our modeling suggests that the sediment de-cementation and the excess pore pressure due to MGH dissociation may indeed have determined the scale of ˜1 km of this initial defect. Our calculations also suggest that dissociation-affected submarine landslides may be common for shallow sea water depths of < 1 km and involve thin sediment layers (usually ˜100 m or less). However, the MGH dissociation may also occur underneath a massive and horizontally extended MGH layer, which could serve as a seal or cap-rock. In this

  14. Assessment of sediment toxicity to marine benthos. (Chapter 9). Book chapter

    SciTech Connect

    Lamberson, J.O.; DeWitt, T.H.; Swartz, R.C.

    1992-01-01

    Most chemical contaminants entering the marine environment eventually accumulate in sediments and, thereby, potentially render the sediments toxic to benthic and demersal organisms. Through deposition, adsorption, diffusion, resuspension, and emigration, sediments serve as both a sink and source for toxic contaminants in the marine environment. The relationship between the concentrations of chemicals in sediments and in the tissues of benthic biota is well established. Although the linkage between bioaccumulation and toxicological responses is poorly documented, logic indicates a strong association. Chemical contaminants in sediments have been implicated as the cause of the abnormal pathology observed in benthic and demersal organisms and the alterations in the structure of benthic invertebrate populations and communities.

  15. Isolation of naphthalene-degrading bacteria from tropical marine sediments.

    PubMed

    Zhuang, W Q; Tay, J H; Maszenan, A M; Tay, S T L

    2003-01-01

    Oil pollution is a major environmental concern in many countries, and this has led to a concerted effort in studying the feasibility of using oil-degrading bacteria for bioremediation. Although many oil-degrading bacteria have been isolated from different environments, environmental conditions can impose a selection pressure on the types of bacteria that can reside in a particular environment. This study reports the successful isolation of two indigenous naphthalene-degrading bacteria from oil-contaminated tropical marine sediments by enrichment culture. Strains MN-005 and MN-006 were characterized using an extensive range of biochemical tests. The 16S ribosomal deoxyribonucleic acid (rDNA) sequence analysis was also performed for the two strains. Their naphthalene degradation capabilities were determined using gas chromatography and DAPI counting of bacterial cells. Strains MN-005 and MN-006 are phenotypically and phylogenetically different from each other, and belong to the genera Staphylococcus and Micrococcus, respectively. Strains MN-005 and MN-006 had maximal specific growth rates (micro(max)) of 0.082 +/- 0.008 and 0.30 +/- 0.02 per hour, respectively, and half-saturation constants (K(s)) of 0.79 +/- 0.10 and 2.52 +/- 0.32 mg per litre, respectively. These physiological and growth studies are useful in assessing the potential of these indigenous isolates for in situ or ex situ naphthalene pollutant bioremediation in tropical marine environments.

  16. Bacterial diversity in oil-polluted marine coastal sediments.

    PubMed

    Acosta-González, Alejandro; Marqués, Silvia

    2016-04-01

    Marine environments harbour a persistent microbial seed which can be shaped by changes of the environmental conditions such as contamination by petroleum components. Oil spills, together with small but continuous discharges of oil from transportation and recreational activities, are important sources of hydrocarbon pollution within the marine realm. Consequently, prokaryotic communities have become well pre-adapted toward oil pollution, and many microorganisms that are exposed to its presence develop an active degradative response. The natural attenuation of oil pollutants, as has been demonstrated in many sites, is modulated according to the intrinsic environmental properties such as the availability of terminal electron acceptors and elemental nutrients, together with the degree of pollution and the type of hydrocarbon fractions present. Whilst dynamics in the bacterial communities in the aerobic zones of coastal sediments are well characterized and the key players in hydrocarbon biodegradation have been identified, the subtidal ecology of the anaerobic community is still not well understood. However, current data suggest common patterns of response in these ecosystems. PMID:26773654

  17. Bacterial diversity in oil-polluted marine coastal sediments.

    PubMed

    Acosta-González, Alejandro; Marqués, Silvia

    2016-04-01

    Marine environments harbour a persistent microbial seed which can be shaped by changes of the environmental conditions such as contamination by petroleum components. Oil spills, together with small but continuous discharges of oil from transportation and recreational activities, are important sources of hydrocarbon pollution within the marine realm. Consequently, prokaryotic communities have become well pre-adapted toward oil pollution, and many microorganisms that are exposed to its presence develop an active degradative response. The natural attenuation of oil pollutants, as has been demonstrated in many sites, is modulated according to the intrinsic environmental properties such as the availability of terminal electron acceptors and elemental nutrients, together with the degree of pollution and the type of hydrocarbon fractions present. Whilst dynamics in the bacterial communities in the aerobic zones of coastal sediments are well characterized and the key players in hydrocarbon biodegradation have been identified, the subtidal ecology of the anaerobic community is still not well understood. However, current data suggest common patterns of response in these ecosystems.

  18. Relevance of Palynological Data for Reconstruction of Abrupt Climatic Change in the Neotropics Region, Based on Marine Sediments from the Cariaco Basin, Caribbean Sea

    NASA Astrophysics Data System (ADS)

    Delusina, I.

    2007-05-01

    Pollen analyses from a deep marine core from the anoxic Cariaco Basin, off the coast of Venezuela, encompass the Late Glacial/Bolling-Allerod transition, through the Younger Dryas and into the beginning of the Preboreal. The unique pollen assemblages indicate significant differences, as well as some basic similarities, with pollen results from continental cross-sections and lacustrine deposits of Neotropical regions. Interpretation of the pollen data from these marine sediments must address the specific challenge of distinguishing the climatic signal from preservation patterns in the marine environment. Because the Cariaco Basin acts as a natural sediment trap for rapidly accumulating sediments of marine and terrestrial origin, it provides an opportunity to compare both signals. The pollen assemblages in the basin mirror the complex altitudinal zonation of the coastal vegetation as well as its dynamics in the marine environment which went through the oxic-anoxic transition. Correlation of the pollen data with percentage of sediment lightness, oxygen isotopes, and titanium/iron concentrations in other Cariaco basin cores, as well as a comparison with vascular plant data, shows that the pollen signal is related to climatic events, rather than to a simple preservation pattern. However, an increase in pollen productivity might not be indicative of climate conditions, but of increased discharge of terrigenous material from the continent. The relative constancy in the pollen list and the gradual change in the percentage of counted palynomorphs and the diversity of pollen assemblages speaks to altitudinal reconstruction of vegetation. Thus, the Montana rain forest predominated over deciduous Montana forest or Paramo elements during Bolling-Allerod time, but didn't replace them. At the end of the Late Glacial and in the middle of Younger Dryas time, seasonally dry forest prevailed. At the end of a Heinrich Event (ca 15,500 cal B.P.), the largest shift in vegetation

  19. Tritirachium candoliense sp. nov., a novel basidiomycetous fungus isolated from the anoxic zone of the Arabian Sea.

    PubMed

    Manohar, Cathrine Sumathi; Boekhout, Teun; Müller, Wally H; Stoeck, Thorsten

    2014-02-01

    A fungal culture (FCAS11) was isolated from coastal sediments of the Arabian Sea during the anoxic season. Multigene phylogenetic analyses confidentially place the organism as a novel species within the recently defined class Tritirachiomycetes, subphylum Pucciniomycotina, phylum Basidiomycota. We named the new species Tritirachium candoliense and provide the first description of a member of this class from a marine environment. DNA sequences and morphological characters distinguish T. candoliense from previously described Tritirachium species. Its growth characteristics, morphology, and ultrastructural features showed that under anoxic conditions the species grows slowly and produces mainly hyphae with only few blastoconidia. Electron microscopy revealed differences when the culture was exposed to anoxic stress. Notable ultrastructural changes occur for example in mitochondrial cristae, irregularly shaped fat globules and the presence of intracellular membrane invaginations. We assume that the growth characteristics and substrate utilization patterns are an adaptation to its source location, the seasonally anoxic environment of the Arabian Sea.

  20. Reduction of elemental selenium to selenide: Experiments with anoxic sediments and bacteria that respire Se-oxyanions

    USGS Publications Warehouse

    Herbel, M.J.; Blum, J.S.; Oremland, R.S.; Borglin, S.E.

    2003-01-01

    A selenite-respiring bacterium, Bacillus selenitireducens, produced significant levels of Se(-II) (as aqueous HSe-) when supplied with Se(O). B. selenitireducens was also able to reduce selenite [Se(IV)] through Se(O) to Se(-II). Reduction of Se(O) by B.selenitireducens was more rapid in cells grown on colloidal sulfur [S(O)] or Se(IV) as their electron acceptor than for cell lines grown on fumarate. In contrast, three cultures of selenate-respiring bacteria, Sulfurospirillum barnesii, B. arsenicoselenatis, and Selenihalanaerobacter shriftii either were unable to reduce Se(O) to Se(-II) or had only a very limited capacity to achieve this reduction. Biological reduction of Se(O) to Se(-II) was observed during incubation of estuarine sediment slurries, while no such activity was noted in formalin-killed controls. The majority of the Se(-II) produced was found in the sediments as a solid precipitate of FeSe, rather than in solution as HSe-. These results demonstrate that certain anaerobic bacteria have the capacity to reduce Se(O) to Se(-II), providing a possible biological explanation for the occurrence of the selenide species in some sedimentary rocks.

  1. Temperature-induced impacts on groundwater quality and arsenic mobility in anoxic aquifer sediments used for both drinking water and shallow geothermal energy production.

    PubMed

    Bonte, Matthijs; van Breukelen, Boris M; Stuyfzand, Pieter J

    2013-09-15

    Aquifers used for the production of drinking water are increasingly being used for the generation of shallow geothermal energy. This causes temperature perturbations far beyond the natural variations in aquifers and the effects of these temperature variations on groundwater quality, in particular trace elements, have not been investigated. Here, we report the results of column experiments to assess the impacts of temperature variations (5°C, 11°C, 25°C and 60°C) on groundwater quality in anoxic reactive unconsolidated sandy sediments derived from an aquifer system widely used for drinking water production in the Netherlands. Our results showed that at 5 °C no effects on water quality were observed compared to the reference of 11°C (in situ temperature). At 25°C, As concentrations were significantly increased and at 60 °C, significant increases were observed pH and DOC, P, K, Si, As, Mo, V, B, and F concentrations. These elements should therefore be considered for water quality monitoring programs of shallow geothermal energy projects. No consistent temperature effects were observed on Na, Ca, Mg, Sr, Fe, Mn, Al, Ba, Co, Cu, Ni, Pb, Zn, Eu, Ho, Sb, Sc, Yb, Ga, La, and Th concentrations, all of which were present in the sediment. The temperature-induced chemical effects were probably caused by (incongruent) dissolution of silicate minerals (K and Si), desorption from, and potentially reductive dissolution of, iron oxides (As, B, Mo, V, and possibly P and DOC), and mineralisation of sedimentary organic matter (DOC and P).

  2. Temperature-induced impacts on groundwater quality and arsenic mobility in anoxic aquifer sediments used for both drinking water and shallow geothermal energy production.

    PubMed

    Bonte, Matthijs; van Breukelen, Boris M; Stuyfzand, Pieter J

    2013-09-15

    Aquifers used for the production of drinking water are increasingly being used for the generation of shallow geothermal energy. This causes temperature perturbations far beyond the natural variations in aquifers and the effects of these temperature variations on groundwater quality, in particular trace elements, have not been investigated. Here, we report the results of column experiments to assess the impacts of temperature variations (5°C, 11°C, 25°C and 60°C) on groundwater quality in anoxic reactive unconsolidated sandy sediments derived from an aquifer system widely used for drinking water production in the Netherlands. Our results showed that at 5 °C no effects on water quality were observed compared to the reference of 11°C (in situ temperature). At 25°C, As concentrations were significantly increased and at 60 °C, significant increases were observed pH and DOC, P, K, Si, As, Mo, V, B, and F concentrations. These elements should therefore be considered for water quality monitoring programs of shallow geothermal energy projects. No consistent temperature effects were observed on Na, Ca, Mg, Sr, Fe, Mn, Al, Ba, Co, Cu, Ni, Pb, Zn, Eu, Ho, Sb, Sc, Yb, Ga, La, and Th concentrations, all of which were present in the sediment. The temperature-induced chemical effects were probably caused by (incongruent) dissolution of silicate minerals (K and Si), desorption from, and potentially reductive dissolution of, iron oxides (As, B, Mo, V, and possibly P and DOC), and mineralisation of sedimentary organic matter (DOC and P). PMID:23870436

  3. Mechanisms of browning development in aggregates of marine organic matter formed under anoxic conditions: A study by mid-infrared and near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Mecozzi, Mauro; Acquistucci, Rita; Nisini, Laura; Conti, Marcelo Enrique

    2014-03-01

    In this paper we analyze some chemical aspects concerning the browning development associated to the aggregation of marine organic matter (MOM) occurring in anoxic conditions. Organic matter samples obtained by the degradation of different algal samples were daily taken to follow the evolution of the aggregation process and the associated browning process. These samples were examined by Fourier transform mid infrared (FTIR) and Fourier transform near infrared (FTNIR) spectroscopy and the colour changes occurring during the above mentioned aggregation process were measured by means of Colour Indices (CIs). Spectral Cross Correlation Analysis (SCCA) was applied to correlate changes in CI values to the structural changes of MOM observed by FTIR and FTNIR spectra which were also submitted to Two-Dimensional Hetero Correlation Analysis (2HDCORR). SCCA results showed that all biomolecules present in MOM aggregates such as carbohydrates, proteins and lipids are involved in the browning development. In particular, SCCA results of algal mixtures suggest that the observed yellow-brown colour can be linked to the development of non enzymatic (i.e. Maillard) browning reactions. SCCA results for MOM furthermore suggest that aggregates coming from brown algae also showed evidence of browning related to enzymatic reactions. In the end 2HDCORR results indicate that hydrogen bond interactions among different molecules of MOM can play a significant role in the browning development.

  4. Mobility of authigenic rhenium, silver, and selenium during postdepositional oxidation in marine sediments

    USGS Publications Warehouse

    Crusius, John; Thomson, John

    2003-01-01

    Sedimentary records of redox-sensitive trace elements hold significant potential as indicators of paleoceanographic environmental conditions. Records of Re can reveal the intensity of past reducing conditions in sediments at the time of deposition, whereas records of Ag may record the magnitude of past diatom fluxes to the seafloor. Confidence in paleoenvironmental reconstruction from records of either metal, however, requires it to have experienced negligible redistribution since deposition. This study examines diagenetic rearrangements of Re and Ag that occur in response to exposure to bottom-water O2 in environments of low sedimentation rate, including Madeira Abyssal Plain turbidites and eastern Mediterranean basin sapropels. Authigenic Re was remobilized quantitatively by oxidation but poorly retained by the underlying sediments. All records are consistent with previous work demonstrating that only a limited reimmobilization of Re occurs preferentially in Corg-rich, reducing sediments. Silver was also mobilized quantitatively by oxidation, but it was subsequently immobilized more efficiently in all cases as sharp peaks immediately into anoxic conditions below active oxidation fronts, and these peaks remain immobile in anoxic conditions during long-term burial. Comparison of Ag, S, and Se records from various cores suggests that Ag is likely to have been immobilized as a selenide, a mechanism previously proposed for Hg in similar situations (Mercone et al., 1999). Coexisting narrow peaks of Ag and Hg with Se offer a means of assessing whether oxidative burndown has ever occurred at the top of Corg- and sulfide-rich sedimentary units. Although these results suggest that caution must be used when inferring paleoenvironmental information from records of Ag and Re in cores with low sediment accumulation rates (−1), they should not affect the promise that authigenic Ag and Re records hold for paleoenvironmental reconstruction in sediments with higher accumulation

  5. 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.

  6. A TOXICITY IDENTIFICATION EVALUATION OF SILTY MARINE HARBOR SEDIMENTS TO CHARACTERIZE PERSISTENT AND NON-PERSISTENT CONSTITUENTS

    EPA Science Inventory

    Sediment toxicity in silty marine harbor sediments is frequently dominated by ammonia or sulfide, leaving the adverse effects of persistent toxic substances unnoticed. To investigate the latter, we subjected interstitial water from three contaminated silty sediments to toxicity i...

  7. Paleomagnetic Studies of Marine Sediments for Evaluation of Sedimentation Rates on the Mendeleev Ridge, Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Elkina, D.

    2014-12-01

    Nowadays the Arctic Ocean is an area of higher scientific interest. Investigation of composition, genesis, sources and source areas of marine sediments is necessary for a gain of geological knowledge and geo-engineering development of the region. One should note that the dating issue in the Arctic Ocean is a challenge by itself. However, magnetostratigraphy can offer a powerful stratigraphic tool applying to marine sediments here. The 6-meters length core was retrieved from the Mendeleev Ridge in 2012 and subjected to paleomagnetic studies. The examined core was revealed to dominate by normal polarity up to 123 cm below seafloor (cmbsf) and assigned there to the Brunhes polarity chron of the geomagnetic field (0.78 Ma). Then prevalence of reverse polarity persists up to 394-397 cmbsf, assigned to Matuyama age, and short positive intervals are believed to be subchrons of normal polarity. Change from reverse to normal polarity at 394-397 cmbsf is considered as the Matuyama - Gauss (2.58 Ma) boundary and is traced up to 530-531 cmbsf including one short reversal. After this depth a drop back to reverse polarity is ascribed to the beginning of the Gilbert polarity chron (3.58 Ma). The resultant magnetostratigraphy is presented on Figure 1. The stepwise alternating field demagnetization and demagnetization by heating were performed to remove viscous overprints and then to define component magnetization directions. Spikes of natural remanent magnetization intensity and magnetic susceptibility are discovered near almost all assigned chron boundaries, and it may act as an independent factor for determination of polarity boundaries. Anisotropy of magnetic susceptibility is also considered in order to find out additional peculiarities of the sedimentation. The relative abundance of shallow inclinations at least implies the existence of secondary processes, which may have altered the paleomagnetic record. The mean sedimentation rates on the Mendeleev Ridge do not exceed 1

  8. Comparison of test specific sediment effect concentrations with marine sediment quality assessment guidelines

    SciTech Connect

    Carr, R.S.; Biedenbach, J.M.; Long, E.R.; MacDonald, D.D.

    1995-12-31

    As part of NOAA`s National Status and Trends (NS and T) Bioeffects Assessment program and studies conducted by the National Biological Service, numerous sediment quality assessment surveys have recently been conducted along the Atlantic and Gulf coasts of the US using the sea urchin (Arbacia punctulata) fertilization and embryological development tests with pore water. Additional toxicity tests were also conducted in conjunction with most of these studies. The areas that have been sampled include Boston harbor, Massachusetts; Charleston Harbor, Winyah Bay, and Savannah River, South Carolina; St. Simon Sound, Georgia; Biscayne Bay, Tampa Bay, Choctawhatchee Bay, Apalachicola Bay, St. Andrew Bay, and Pensacola Bay, Florida; Galveston Bay, Lavaca Bay, and Sabine Lake, Texas, and 200 stations in the vicinity of offshore oil and gas production platforms in the Gulf of Mexico. Sufficient data are now available from this series of surveys to calculate test specific sediment effect concentrations (SECs). Based on these recent studies, SECs were developed for the sea urchin porewater and amphipod tests and compared with existing marine sediment quality assessment guidelines.

  9. Structured Multiple Endosymbiosis of Bacteria and Archaea in a Ciliate from Marine Sulfidic Sediments: A Survival Mechanism in Low Oxygen, Sulfidic Sediments?

    PubMed Central

    Edgcomb, Virginia P.; Leadbetter, Edward R.; Bourland, William; Beaudoin, David; Bernhard, Joan M.

    2011-01-01

    Marine micro-oxic to sulfidic environments are sites of intensive biogeochemical cycling and elemental sequestration, where prokaryotes are major driving forces mediating carbon, nitrogen, sulfur, phosphorus, and metal cycles, important from both biogeochemical and evolutionary perspectives. Associations between single-celled eukaryotes and bacteria and/or archaea are common in such habitats. Here we describe a ciliate common in the micro-oxic to anoxic, typically sulfidic, sediments of Santa Barbara Basin (CA, USA). The ciliate is 95% similar to Parduzcia orbis (18S rRNA). Transmission electron micrographs reveal clusters of at least three different endobiont types organized within membrane-bound sub-cellular regions. Catalyzed reporter deposition–fluorescent in situ hybridization and 16S rRNA clone libraries confirm the symbionts include up to two sulfate reducers (Desulfobulbaceae, Desulfobacteraceae), a methanogen (Methanobacteriales), and possibly a Bacteroidete (Cytophaga) and a Type I methanotroph, suggesting synergistic metabolisms in this environment. This case study is discussed in terms of implications to biogeochemistry, and benthic ecology. PMID:21833311

  10. Targeted search for actinomycetes from nearshore and deep-sea marine sediments.

    PubMed

    Prieto-Davó, Alejandra; Villarreal-Gómez, Luis J; Forschner-Dancause, Stephanie; Bull, Alan T; Stach, James E M; Smith, David C; Rowley, Dave C; Jensen, Paul R

    2013-06-01

    Sediment samples collected off the coast of San Diego were analyzed for actinomycete diversity using culture-independent techniques. Eight new operational taxonomic units (OTUs) in the Streptomycetaceae were identified as well as new diversity within previously cultured marine OTUs. Sequences belonging to the marine actinomycete genus Salinispora were also detected, despite the fact that this genus has only been reported from more tropical environments. Independent analyses of marine sediments from the Canary Basin (3814 m) and the South Pacific Gyre (5126 and 5699 m) also revealed Salinispora sequences providing further support for the occurrence of this genus in deep-sea sediments. Efforts to culture Salinispora spp. from these samples have yet to be successful. This is the first report of Salinispora spp. from marine sediments > 1100 m and suggests that the distribution of this genus is broader than previously believed. PMID:23360553

  11. EXTRACTION OF ORGANIC CONTAMINANTS FROM MARINE SEDIMENTS AND TISSUES USING MICROWAVE ENERGY

    EPA Science Inventory

    In this study, we compared microwave solvent extraction (MSE) to conventional methods for extracting organic contaminants from marine sediments and tissues with high and varying moisture content. The organic contaminants measured were polychlorinated biphenyl (PCB) congeners, chl...

  12. Microbes of deep marine sediments as viewed by metagenomics

    NASA Astrophysics Data System (ADS)

    Biddle, J.

    2015-12-01

    Ten years after the first deep marine sediment metagenome was produced, questions still exist about the nucleic acid sequences we have retrieved. Current data sets, including the Peru Margin, Costa Rica Margin and Iberian Margin show that consistently, data forms larger assemblies at depth due to the reduced complexity of the microbial community. But are these organisms active or preserved? At SMTZs, a change in the assembly statistics is noted, as well as an increase in cell counts, suggesting that cells are truly active. As depth increases, genome sizes are consistently large, suggesting that much like soil microbes, sedimentary microbes may maintain a larger reportorie of genomic potential. Functional changes are seen with depth, but at many sites are not correlated to specific geochemistries. Individual genomes show changes with depth, which raises interesting questions on how the subsurface is settled and maintained. The subsurface does have a distinct genomic signature, including unusual microbial groups, which we are now able to analyze for total genomic content.

  13. Deposition of zinc and cadmium by marine bacteria in estuarine sediments

    USGS Publications Warehouse

    McLerran, C.J.; Holmes, Charles W.

    1974-01-01

    Mixed cultures of marine bacteria isolated from the sediments of Corpus Christi Harbor were examined for their ability to assimilate or precipitate radioactive zinc and cadmium from solution. Test data indicate that during summer, when bacterial activity is at a maximum, the bacteria and their metabolic byproducts play a significant role in the removal of zinc and cadmium from seawater and their subsequent deposition in marine sediments.

  14. D/H Ratios of Marine Lipids from Santa Barbara Basin Sediments

    NASA Astrophysics Data System (ADS)

    Li, C.; Sessions, A.; Kinnaman, F.; Valentine, D.

    2006-12-01

    With the early successful application of compound-specific D/H analyses to reconstructing paleoclimate records, most subsequent research has focused on understanding organic D/H fractionations in terrestrial environments. Thus we still know very little about natural D/H variations in lipids derived from marine organisms, or indeed if any such variations exist. We have therefore conducted an extensive survey of lipid δD values in two sediment cores collected in the Santa Barbara Basin. These data allow us to examine 1) variations between the lipid products of different organisms, 2) down-core variations due to diagenesis, and 3) differences between sediments deposited under oxic or anoxic bottom-water conditions. Our results show that considerable D/H variability between different marine products does exist. δD values of n-alkanes (except n-C35) ranged from -94 to -175 ‰, and exhibit a systematic offset between odd and even carbon numbers. The δD value of n-C35 is anomalous at -220‰. Isotopic compositions of n-alkanols range from -126 to -221 , with a pattern of progressive D depletion with chain length observed for free alcohols. δD values of sterols range from -215 to -309‰, and show no systematic variation with carbon number. However, offsets do exist between the saturated, monounsaturated, and diunsaturated sterols. Sterols as a group are strongly depleted in D relative to the bacterial-derived hopanols (-166 to -232‰), suggesting possible differences in biosynthetic fractionations by bacteria and eukaryotes. Phytol and phytane δD values roughly ranged from -360 to -410‰, while phytanol was systematically enriched at -300 to -340‰. Fatty acids encompassed much greater variability, with dD values ranging from -55 to -270‰. In general, saturated fatty acids are enriched in D relative to their unsaturated analogs, and long-chain (>C24) acids are enriched in D relative to short-chain (

  15. USE OF ULVA LACTUCA TO DISTINGUISH PH DEPENDENT TOXICANTS IN MARINE WATERS AND SEDIMENTS

    EPA Science Inventory

    Ulva lactuca (sea lettuce) is a cosmopolitan marine attached green seaweed capable of sequestering high environmental levels of ammonia. Ammonia can be acutely toxic to marine organisms and is often found in dredged sediments from highly industrial areas or from areas with high c...

  16. Enumeration and phylogenetic analysis of polycyclic aromatic hydrocarbon-degrading marine bacteria from Puget Sound sediments

    SciTech Connect

    Geiselbrecht, A.D.; Herwig, R.P.; Deming, J.W.; Staley, J.T.

    1996-09-01

    Polycyclic aromatic hydrocarbons (PAHs) are primarily released into the environment through anthropomorphic sources. PAH degradation has been known to occur in marine sediments. This paper describes the enumeration, isolation, and preliminary characterization of PAH-degrading strains from Puget Sound sediments. 38 refs., 3 figs., 3 tabs.

  17. Thermal alteration of organic matter in recent marine sediments. 2: Isoprenoids. [Tanner Basin off Southern California

    NASA Technical Reports Server (NTRS)

    Ikan, R.; Baedecker, M. J.; Kaplan, I. R.

    1974-01-01

    A series of isoprenoid compounds were isolated from a heat treated marine sediment (from Tanner Basin) which were not present in the original sediment. Among the compounds identified were: phytol, dihydrophytol, c-18-isoprenoid ketone, phytanic and pristanic acids, c-19 and c-20-monoolefines, and the alkanes pristane and phytane. The significance and possible routes leading to these compounds is discussed.

  18. Molecular Approaches to Understanding C & N Dynamics in MArine Sediments

    SciTech Connect

    Arturo Massol; James Tiedje; Jizhong Zhou; Allan Devol

    2007-05-16

    Continental margin sediments constitute only about 10% of the total sediment surface area in the world’s oceans, nevertheless they are the dominant sites of nitrogen (N) cycling. Recent studies suggest that the oceanic nitrogen budget is unbalanced, primarily due to a higher nitrogen removal rate in contrast to the fixation rate, and it has been suggested that denitrification activity contributes significantly to this imbalance. Although denitrification in marine environments has been studied intensively at the process level, little is known about the species abundance, composition, distribution, and functional differences of the denitrifying population. Understanding the diversity of microbial populations in marine environments, their responses to various environmental factors such as NO3-, and how this impact the rate of denitrification is critical to predict global N dynamics. Environmental Microbiology has the prompt to study the influence of each microbial population on a biogeochemical process within a given ecosystem. Culture-dependent and –independent techniques using nucleic acid probes can access the identity and activity of cultured and uncultured microorganisms. Nucleic acid probes can target distintict genes which set phylogenetic relationships, such as rDNA 16S, DNA gyrase (gyrB) and RNA polymerase sigma 70 factor (rpoD). In the other hand, the genetic capabilities and their expression could be tracked using probes that target several functional genes, such as nirS, nirK, nosZ, and nifH, which are genes involved in denitrification. Selective detection of cells actively expressing functional genes within a community using In Situ Reverse Transcription-PCR (ISRT-PCR) could become a powerful culture-independent technique in microbial ecology. Here we describe an approach to study the expression of nirS genes in denitrifying bacteria. Pure cultures of Pseudomonas stutzeri and Paracoccus denitrificans, as well as co-cultures with non

  19. Autigenic and Anthropogenic Uranium in the Marine Sediments of the Gulf of California in Front of Santa Rosalia Mining District

    NASA Astrophysics Data System (ADS)

    Choumiline, K.; Rodríguez-Figueroa, G.; Shumilin, E.; Sapozhnikov, D.

    2007-05-01

    To verify the possibilities of U enrichments in the marine sedimentary environment of the eastern sector of the central Gulf of Califoria (GC), eleven sediment cores were collected in front of the Santa Rosalia mining region, peninsula of Baja California. Uranium and some other trace element contents in sliced core layers, dried and homogenized, were determined using instrumental neutron activation analysis. Average total U contents in sediments of five cores collected in the open GC in front of Santa Rosalía at sites with water depths from 265 m to 1030 m and in the Guaymas Basin with 2019 m, ranged from 1.36±0.26 mg kg-1 (Guaymas Basin) to 9.31±3.03 mg kg-1 (SR63 core, depth 630 m). To distinguish non-lithogenic U from the lithogenic one, the normalization of total U contents to the concentrations of Sc in the samples was used. That because this element is a reliable indicator of crustal materials, mainly aluminosilicates in the marine sediments. The relative contribution of non-lithogenic (authigenic) U varied from 49.8±3 % (Guaymas Basin) to 84.2±8.2 % (SR62 core) of the total U content in the sediments of the open central GC. Surprisingly, in three sediment cores from the coastal zone adjacent to the town of Santa Rosalía in water depth range 3-6 m very high concentrations of total U were found, ranging from 54.2±7.3 mg kg-1 (SR4 core) to 110±13 mg kg-1 (SR2 core) and exceeding not only U average abundance in the earth´s crust (2.7 mg kg-1), but also its levels found for SR62 core, as well as those reported for natural enrichments of U in suboxic-anoxic environments, e.g. at Mexico and Peru margin sites (3.04 mg kg-1 - 24.54 mg kg-1, McManus et al., 2006). The relative contribution of non-lithogenic U in the sediments of these three anomalous cores varied from 97.2±0.4 % (SR4 core) to 98.80.2 % (SR1 and SR2 cores) of their total U content. The sediments were also depleted in organic C (0.05 % - 0.18 %), which is not typical for marine solid phases

  20. Maribacter lutimaris sp. nov., isolated from marine sediment.

    PubMed

    Kim, Kyung Hyun; Jin, Hyun Mi; Jeong, Hye Im; Jeon, Che Ok

    2016-04-01

    A Gram-staining-negative, moderately halophilic and strictly aerobic bacterium, designated strain KJ4T, was isolated from marine sediment at Gangjin in South Korea. Cells were catalase- and oxidase-positive long rods with gliding motility. Growth of strain KJ4T was observed at 4-37 °C (optimum, 15-25 °C), at pH 6.0-9.0 (optimum, pH 7.0-8.5) and in the presence of 1.0-7.0% (w/v) NaCl (optimum, 2.0-5.0%). Menaquinone 6 (MK-6) was the only isoprenoid quinone detected and iso-C15:0, iso-C17:0 3-OH, iso-C15:1 G and summed feature 3 (comprising C16:1ω7c and/or C16:1ω6c) were the major cellular fatty acids. The polar lipids of strain KJ4T consisted of phosphatidylethanolamine, an unidentified aminophospholipid and five unidentified lipids. The G+C content of the genomic DNA was 38.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain KJ4T formed a distinct phylogenetic lineage within the genus Maribacter. Strain KJ4T was most closely related to Maribacter orientalis KMM 3947T with 97.4% 16S rRNA gene sequence similarity. On the basis of phenotypic, chemotaxonomic and molecular features, strain KJ4T clearly represents a novel species of the genus Maribacter, for which the name Maribacter lutimaris sp. nov. is proposed. The type strain is KJ4T (=KACC 16438T=JCM 31154T). PMID:26828017

  1. Tropicimonas sediminicola sp. nov., isolated from marine sediment.

    PubMed

    Shin, Na-Ri; Roh, Seong Woon; Kim, Min-Soo; Yun, Bora; Whon, Tae Woong; Kim, Young-Ok; Bae, Jin-Woo

    2012-10-01

    A novel Gram-negative, obligately aerobic, non-motile, rod-shaped bacterium, strain M97(T), was isolated from marine sediment of a cage-cultured ark clam farm on the south coast of Korea. Strain M97(T) was positive for oxidase and catalase. Optimal growth occurred at 37 °C, with 1-2 % (w/v) NaCl and at pH 7-8. The main cellular fatty acids were C(16 : 0), C(18 : 1)ω7c, C(12 : 0) 3-OH and cyclo-C(19 : 0)ω8c. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, an unknown aminolipid and three unknown lipids. The predominant respiratory quinone was ubiquinone-10 (Q-10). Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain M97(T) belongs to the genus Tropicimonas, with highest sequence similarity to Tropicimonas aquimaris DPG-21(T) (99.0 %). The DNA G+C content of strain M97(T) was 68.5 mol%. Mean DNA-DNA relatedness between strain M97(T) and T. aquimaris DPG-21(T) was 46 ± 10 %. Based on phylogenetic, phenotypic and genotypic analyses, strain M97(T) is considered to represent a novel species of the genus Tropicimonas, for which the name Tropicimonas sediminicola sp. nov. is proposed. The type strain is M97(T) ( = KACC 15544(T) = JCM 17731(T)). PMID:22140172

  2. Deinococcus enclensis sp. nov., isolated from a marine sediment sample.

    PubMed

    Thorat, Meghana N; Mawlankar, Rahul; Sonalkar, Vidya V; Venkata Ramana, V; Joseph, Neetha; Shouche, Yogesh S; Dastager, Syed G

    2015-01-01

    A novel pale-pink coloured strain, designated NIO-1023(T), was isolated from a marine sediment sample from Chorao Island, Goa, India. The taxonomic position of strain NIO-1023(T) was investigated by using a polyphasic approach. The cells were observed to be Gram-stain positive, coccal shaped and non-spore forming. Phylogenetic analyses using the 16S rRNA gene sequence of the isolate indicated that the organism belongs to the genus Deinococcus. The strain NIO-1023(T) showed highest 16S rRNA gene sequence similarities with Deinococcus ficus (97.8 %), whereas other Deinococcus species showed less than 95 % sequence similarity. The DNA-DNA relatedness with respect to D. ficus CC-FR2-10(T) was 23.9 %. Chemotaxonomic data revealed that strain NIO-1023(T) contains only menaquinone MK-8 as the respiratory quinone and a complex polar lipid profile consisting of different unidentified glycolipids and polar lipids, two unknown phospholipids and three unknown phosphoglycolipids. As in other deinococci, one of these phosphoglycolipids was predominant in the profile. The predominant fatty acids were identified as C17:1 w8c, C16:1 w6c/w7c, C15:1 w6c and C17:1 w9c. The genomic DNA G + C content of strain NIO-1023(T) was determined to be 67.2 mol%. The biochemical and chemotaxonomic properties demonstrate that strain NIO-1023(T) represents a novel species, for which the name Deinococcus enclensis sp. nov. is proposed. The type strain is NIO-1023(T) (=DSM 25127(T) = NCIM 5456(T)).

  3. Pseudonocardia sediminis sp. nov., isolated from marine sediment.

    PubMed

    Zhang, Dao-Feng; Jiang, Zhao; Li, Li; Liu, Bing-Bing; Zhang, Xiao-Mei; Tian, Xin-Peng; Zhang, Si; Li, Wen-Jun

    2014-03-01

    A Gram-stain-positive, aerobic actinomycete, designated strain YIM M13141(T), was isolated from a marine sediment sample from the South China Sea, and its taxonomic position was determined using a polyphasic approach. The strain produced branched substrate mycelium and aerial hyphae, but no diffusible pigments were produced on the media tested. At maturity, substrate mycelium was fragmented and spore chains were formed on aerial hyphae and substrate mycelium. Optimum growth occurred at 28 °C, 1-3% (w/v) NaCl and pH 7.0. Comparative analysis of the 16S rRNA gene sequence showed that the isolate belongs to the genus Pseudonocardia, showing highest levels of similarity with respect to Pseudonocardia sichuanensis KLBMP 1115(T) (97.1%), Pseudonocardia tetrahydrofuranoxydans K1(T) (97.1%) and Pseudonocardia kunmingensis YIM 63158(T) (97.0%). Whole-organism hydrolysates of the strain contained meso-diaminopimelic acid and the sugars galactose, glucose, mannose and arabinose. The predominant menaquinone was MK-8(H4). The polar lipids detected were diphosphatidylglycerol, phosphatidylcholine, phosphatidylinositol, phosphatidylmethylethanolamine, phosphatidylethanolamine, two unknown phosphoglycolipids and two glycolipids. The major fatty acid was iso-C16 : 0. The G+C content of the genomic DNA was 73.1 mol%. DNA-DNA relatedness with P. tetrahydrofuranoxydans DSM 44239(T) was 42.8 ± 3.5% (mean±sd). Based on phylogenetic analysis, phenotypic and genotypic data, it is concluded that the isolate represents a novel species of the genus Pseudonocardia, for which the name Pseudonocardia sediminis sp. nov. is proposed. The type strain is YIM M13141(T) ( = DSM 45779(T) = JCM 18540(T)).

  4. Bacillus tianshenii sp. nov., isolated from a marine sediment sample.

    PubMed

    Jiang, Zhao; Zhang, Dao-Feng; Khieu, Thi-Nhan; Son, Chu Ky; Zhang, Xiao-Mei; Cheng, Juan; Tian, Xin-Peng; Zhang, Si; Li, Wen-Jun

    2014-06-01

    A novel Gram-stain-positive, motile, catalase- and oxidase-positive, aerobic, endospore-forming, peritrichous, rod-shaped bacterium, designated YIM M13235(T), was isolated from a marine sediment sample collected from the South China Sea. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain YIM M13235(T) belonged to the genus Bacillus. The strain grew optimally at 30 °C, pH 7.0 and in the presence of 2-4% (w/v) NaCl. meso-Diaminopimelic acid was present in the cell-wall peptidoglycan. Strain YIM M13235(T) exhibited a menaquinone system with MK-7, and the major polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, four unknown phospholipids and one unknown glycolipid. The major fatty acids (>5%) were iso-C(15 : 0), anteiso-C(15 : 0), anteiso-C(17 : 0), iso-C(17 : 1)ω10c and summed feature 4 (anteiso-C(17 : 1) and/or iso-C(17 : 1)). The genomic DNA G+C content was 42.1 mol%. The DNA-DNA relatedness values between strain YIM M13235(T) and its close relatives (16S rRNA gene sequence similarities >97%) including Bacillus halmapalus DSM 8723(T), Bacillus horikoshii DSM 8719(T) and Bacillus zhanjiangensis JSM 099021(T) were 41%, 44% and 44%, respectively. On the basis of genotypic, phenotypic and DNA-DNA relatedness data, it is apparent that strain YIM M13235(T) represents a novel species of the genus Bacillus, for which the name Bacillus tianshenii sp. nov. is proposed. The type strain is YIM M13235(T) ( = DSM 25879(T) = KCTC 33044(T)).

  5. Idiomarina maris sp. nov., a marine bacterium isolated from sediment.

    PubMed

    Zhang, Yan-Jiao; Zhang, Xi-Ying; Zhao, Hui-Lin; Zhou, Ming-Yang; Li, Hui-Juan; Gao, Zhao-Ming; Chen, Xiu-Lan; Dang, Hong-Yue; Zhang, Yu-Zhong

    2012-02-01

    A protease-producing marine bacterium, designated CF12-14(T), was isolated from sediment of the South China Sea. Phylogenetic analysis of the 16S rRNA gene sequence revealed that strain CF12-14(T) formed a separate lineage within the genus Idiomarina (Gammaproteobacteria). The isolate showed the highest 16S rRNA gene sequence similarity with Idiomarina salinarum ISL-52(T) (94.7 %), Idiomarina seosinensis CL-SP19(T) (94.6 %) and other members of the genus Idiomarina (91.9-94.6 %). Cells were gram-negative, aerobic, flagellated, straight or slightly curved, and often formed buds and prosthecae. Strain CF12-14(T) grew at 4-42 °C (optimum 30-35 °C) and with 0.1-15 % (w/v) NaCl (optimum 2-3 %). The isolate reduced nitrate to nitrite and hydrolysed DNA, but did not produce acids from sugars. The predominant cellular fatty acids were iso-C(15 : 0) (27.4 %), iso-C(17 : 0) (16.0 %) and iso-C(17 : 1)ω9c (15.8 %). The major polar lipids were phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. The major respiratory quinone was ubiquinone 8. The DNA G+C content was 50.4 mol%. The phylogenetic, phenotypic and chemotaxonomic data supported the conclusion that CF12-14(T) represents a novel species of the genus Idiomarina, for which the name Idiomarina maris sp. nov. is proposed. The type strain is CF12-14(T) ( = CCTCC AB 208166(T) = KACC 13974(T)).

  6. Influence of water column anoxia and sediment supply on the burial and preservation of organic carbon in marine shales

    NASA Astrophysics Data System (ADS)

    Calvert, S. E.; Bustin, R. M.; Ingall, E. D.

    1996-05-01

    in the latter. δ 15N values are 1.9z.permil; lighter on average in laminated compared with bioturbated intervals, suggesting that nutrient drawdown was less during the deposition of the organic-rich, laminated shales. The chemical, mineralogical, and isotopic contrasts between the two shale facies of the Camp Run Member indicate that the conditions of sedimentation were different during their deposition. The difference was possibly related to variations in sea level, which would have caused the Camp Run shoreline to move closer to and farther from the core site, causing, in turn, the deposition of coarser and finer grained sediments that contained different mixtures of marine and terrestrial organic matter. Bottomwater conditions were anoxic during deposition of most laminated intervals. Bottom-water anoxia or dysoxia led to decreased burial and preservation of the essential nutrient phosphorus in the laminated, organic-rich shales relative to the rocks deposited beneath better oxygenated bottomwaters. Increased availability of phosphorus in the water column on long timescales leads to increased productivity and a higher settling flux of organic matter, causing bottom-water oxygen levels to fall. This is consistent with the nitrogen isotope evidence suggesting that production was probably higher during the deposition of the organic-rich shales. Thus, production variations coupled with enhanced sedimentary regeneration of phosphorus from sediments related to low oxygen bottom-water concentrations provide a general mechanism for the formation of the alternating facies of this member of the New Albany Shale.

  7. IDENTIFICATION OF TOXICANTS IN WHOLE MARINE SEDIMENTS: METHODS AND RESULTS

    EPA Science Inventory

    Identification of stressors in aquatic systems is critical to sound assessment and management of our nation's waterways. Information from stressor identification can be useful in designing effective sediment remediation methods, assessing options for sediment disposal, allowing m...

  8. Studies of the DOM aqueous extracts from coastal marine sediments

    NASA Astrophysics Data System (ADS)

    Sakellariadou, F.

    2012-04-01

    Dissolved organic matter (DOM) represents a major exchangeable organic pool playing an outstanding role in the ocean carbon cycle. It has a complex chemical structure made up of a wide range of organic molecules. The composition of DOM depends on the sources proximity and the exposure to any sort of degradation mechanism. The coloured (or chromophoric) dissolved organic matter (CDOM), representing the optically active fraction of DOM, consists of aromatic rings able to absorb light in the visible and UV regions (Kirk, 1994) and fluorophoric molecules that emit light. The main fluorophoric moieties of CDOM are humic material with a blue fluorescence and protein material with an ultraviolet (UV) fluorescence (Mopper and Schultz, 1993). Dissolved organic matter interacts with pollutants either by enhancing their bioavailability or by influencing their transportation to the soluble phase. In addition, DOM affects the remineralisation of carbon and its preservation in marine sediments. Referring to its origin, it can be terrestrial, freshwater or marine one. Fluorescence spectroscopy is a technique widely applied for the identification and characterization of organic matter, being fast, simple, non-destructive and sensitive. In addition, the fluorescence analysis for the physico-chemical characterization of organic matter requires a small amount of aqueous sample at a low concentration, in comparison with the large sample volumes needed for conventional techniques. At the present study coastal sediment samples were collected from Messiniakos gulf in the south western Peloponnese in South Greece. Messiniakos gulf has a seabed dominated by very abrupt inclinations reaching depths of more than 1000m. All samples, according to their grain size, are classified as fine clayey silt. Dissolved organic matter was extracted under gentle extraction conditions (4 mM CaCl2 solution). The various classes of organic components present at the DOM aqueous extracts were characterised by

  9. Nonlinear Raman-Type Acoustic Scattering in Three-Phase Marine Sediments

    NASA Astrophysics Data System (ADS)

    Pushkina, N. I.

    2001-03-01

    Stimulated Raman-type acoustic scattering by bubble oscillations in three-phase marine sediments, which consist of a solid frame, the pore water, and air bubbles, is considered. A model is developed for the case of the bubbles surrounded by water. The acoustic properties of the sediments are described on the basis of the Biot theory of sound propagation in a fluid-saturated porous medium. Nonlinear wave equations are obtained for marine sediments containing air bubbles. Expressions for the nonlinear scattering coefficient and the threshold intensity of the exciting sound wave are derived. A possibility of an experimental observation of the scattering process is discussed.

  10. The remedial investigation of marine sediment at the United Heckathorn Superfund site

    SciTech Connect

    White, P.J.; Kohn, N.P.; Gardiner, W.W.; Word, J.Q.

    1994-02-01

    The former United Heckathom site in Richmond, California, was used to process and package chlorinated pesticides from the 1940s to the mid-1960s. These activities resulted in the contamination of upland soils and marine sediment in the adjacent waterways. Battelle/Marine Sciences Laboratory (MSL) was requested by USEPA to conduct a remedial investigation and feasibility study (RI/FS). of the marine portion of the site. The objectives of this RI are to determine the extent of pesticide contamination in inner Richmond Harbor, estimate the total volume of contaminated sediment, characterize the subsurface geology; characterize the biological effects of contaminated sediment; and characterize the quality of effluent derived from dewatered sediment through treatability testing. Sediment cores were collected from 53 stations. Vertical subsamples from each sediment core were analyzed for chlorinated pesticides. Sediment from selected cores was also analyzed for other contaminants. Younger Bay Mud (YBM) sediment from multiple stations was mixed to form composite samples representing various segments of the study area. These composites were used for solid-phase toxicity and bioaccumulation tests, and the preparation of liquid-phase samples for treatability testing. The probable quality of effluent produced by dewatering sediment was evaluated by chemical and toxicological testing of suspended-particulate-phase (SPP) and elutriate samples.

  11. Marine ciliates as a widespread source of tetrahymanol and hopan-3. beta. -ol in sediments

    SciTech Connect

    Harvey, H.R.; McManus, G.B. )

    1991-11-01

    The authors observed tetrahymanol (gammaceran-3{beta}-ol) as a principal neutral lipid in eight marine ciliate species, most of which were scuticociliates, a group of ciliates that feeds mainly on bacteria. Tetrahymanol abundance in pure cultures and field samples (sediment traps, water column particulates, and enrichments from coastal and estuarine environments) shows good agreement with ciliate biovolume (R{sup 2} = 0.89), suggesting that tetrahymanol is a specific marker for marine ciliates that feed on bacteria. Hopan-3{beta}-ol was also positively identified in several ciliates, but did not occur in all species examined. Because of their widespread distribution in modern marine systems, these organisms provide a likely source for the common appearance of tetrahymanol in many marine sediments. By analogy, the presumed presence of ciliates in ancient seas may explain the occurrence of its diagenetic product, gammacerane, in more mature sediments and crude oils.

  12. Biogeochemical cycling in an organic-rich coastal marine basin. 8. A sulfur isotopic budget balanced by differential diffusion across the sediment-water interface

    USGS Publications Warehouse

    Chanton, J.P.; Martens, C.S.; Goldhaber, M.B.

    1987-01-01

    The sulfur isotopic composition of the sulfur fluxes occurring in the anoxic marine sediments of Cape Lookout Bight, N.C., U.S.A., was determined, and the result of isotopic mass balance was obtained via the differential diffusion model. Seasonal pore water sulfate ??34S measurements yielded a calculated sulfate input of 0.6%.. Sulfate transported into the sediments via diffusion appeared to be enriched in the lighter isotope because its concentration gradient was steeper, due to the increase in the measured isotopic composition of sulfate with depth. Similarly, the back diffusion of dissolved sulfide towards the sediment-water interface appeared enriched in the heavier isotope. The isotopic composition of this flux was calculated from measurements of the ??34S of dissolved sulfide and was determined to be 15.9%.. The isotopic composition of buried sulfide was determined to be -5.2%. and the detrital sulfur input was estimated to be -6.2%.. An isotope mass balance equation based upon the fluxes at the sediment-water interface successfully predicted the isotopic composition of the buried sulfur flux within 0.5%., thus confirming that isotopes diffuse in response to their individual concentration gradients. ?? 1987.

  13. Dissolved and particulate carbohydrates in contrasting marine sediments

    NASA Astrophysics Data System (ADS)

    Burdige, D. J.; Skoog, A.; Gardner, K.

    2000-03-01

    Dissolved and particulate carbohydrates were examined in contrasting Chesapeake Bay (estuarine) and mid-Atlantic shelf/slope break (continental margin) sediments. Particulate carbohydrates (PCHOs) represented ˜5-9% of the total sediment particulate organic carbon (POC), and PCHO remineralization appeared to be a similar fraction of total sediment carbon oxidation (or C ox). When these results are compared with results from other coastal sediments and a pelagic turbidite, PCHO remineralization (as a percentage of C ox) did not vary by more than a factor of ˜2-3 over a 3-4 order of magnitude range in C ox values. The causes of this are not well understood, but may be related to specific effects associated with the remineralization of highly altered organic matter mixtures under aerobic conditions. Dissolved carbohydrates (DCHOs) in these sediment pore waters ranged from ˜30 to 400 μM, increased with depth in a manner similar to total DOC, and represented ˜10 to 55% of pore water DOC. In Chesapeake Bay sediments this percentage decreased with sediment depth, while in these continental margin sediments it was constant (upper 30 cm). Of the DCHOs in these pore waters ˜30 to 50% could be identified as individual aldoses (monomeric neutral sugars), and total aldose yields (individual aldoses as a percentage of total DOC) were higher in these continental margin sediment pore waters (>9%) than they were in the estuarine sediment pore waters (<5%). A comparison of DCHO and PCHO concentrations in these sediments indicates that their concentrations are uncoupled, and that pore water DCHO concentrations are primarily controlled by sediment remineralization processes. Pore water DCHOs appeared to be preferentially found in the high molecular weight (HMW) DOC pool, and likely occur as some of the initial HMW intermediates produced and consumed during sediment POC remineralization. These results also support past suggestions about the differing controls on carbon

  14. Endogenous isolation of replicon probes for assessing plasmid ecology of marine sediment microbial communities.

    PubMed

    Cook, M A; Osborn, A M; Bettandorff, J; Sobecky, P A

    2001-08-01

    Six functional replication origins (repGA14, repGA33, repGA70, repSD41, repSD164 and repSD172), obtained from endogenously isolated, broad-host-range (BHR) marine plasmids ranging in size from 5 to 60 kb, were used to determine plasmid occurrence in three coastal marine sediment sites (in California, Georgia and South Carolina, USA). The plasmid-specific replicons were isolated from plasmid-bearing marine sediment bacteria belonging to the alpha and gamma subclasses of the Proteobacteria. The plasmid sources of the endogenous replicons were considered to be cryptic due to a lack of identifiable phenotypic traits. The putative Rep proteins from a number of these replicons showed similarity to replicons of two recognized families: RCR group III (repSD164) and the FIA family of theta group A (repSD41, repSD121, repGA33 and repGA14). Plasmids isolated from marine bacteria belonging to the genera Pseudoalteromonas, Shewanella and Vibrio cultivated from geographically different coastal sites exhibited homology to two of the marine plasmid replicons, repSD41 and repGA70, obtained from a Vibrio sp. The repGA33 plasmid origin, obtained from a Shewanella sp. isolated from coastal Georgia, was detected in 7% of the Georgia marine sediment Shewanella sp. isolates. Microbial community DNA extracted from marine sediments was also screened for the presence of the plasmid replication sequences. Community DNA samples amplified by PCR yielded a positive signal for the repSD172 and repGA14 replication sequences. The replication origin of BHR plasmid RK2 (IncP) was also detected in marine Vibrio sp. and microbial community DNA extracted from the three coastal sites. These findings provide molecular evidence that marine sediment bacteria harbour an untapped population of BHR plasmids.

  15. Cs-137 geochronology, epithermal neutron activation analysis, and principal component analysis of heavy metals pollution of the Black Sea anoxic continental shelf sediments

    NASA Astrophysics Data System (ADS)

    Duliu, O. G.; Cristache, C.; Oaie, G.; Culicov, O. A.; Frontasyeva, M. V.

    2009-04-01

    Anthropogenic Cs-137 Gamma-ray Spectroscopy assay (GrSA) performed at the National Institute of Research and Development for Physics and Nuclear Engineering - Bucharest (Romania) in correlation with Epithermal Neutrons Activation Analysis (ENAA) performed at the Joint Institute of Nuclear Researches - Dubna (Russia) were used to investigate a 50 cm core containing unconsolidated sediments collected at a depth of 600 m off Romanian town of Constantza, located in the anoxic zone of the Black Sea Continental Shelf. A digital radiography showed the presence of about 265 distinct laminae, 1 to 3 mm thick, a fact attesting a stationary sedimentary process, completely free of bioturbation. After being radiographed, the core was sliced into 45 segments whose thickness gradually increased from 0.5 to 5 cm, such that the minimum thickness corresponded to the upper part of the core. From each segment two aliquots of about 0.5 g and 50 g were extracted for subsequent ENAA and Cs-137 GrSA. The Cs-137 vertical profile evidenced two maxima, one of them was very sharp and localized at a depth of 1 cm and the other very broad, almost undistinguished at about 8 cm depth, the first one being attributed to 1986 Chernobyl accident. Based on these date, we have estimated a sedimentation ratio of about 0.5 mm/year, value taken as reference for further assessment of recent pollution history. By means of ENAA we have determined the vertical content of five presumed pollutants, e.i. Zn, As, Br, Sn and Sb and of Sc, as natural, nonpolluting element. In the first case, all five elements presented a more or less similar vertical profile consisting of an almost exponential decrease for the first 10 cm below sediment surface followed by a plateau until the core base, i.e. 50 cm below surface, dependency better described by the equation: c(z) = c0 [1+k exp (-z/Z)] (1) where: where c(z) represents the concentration vertical profile; z represents depth (in absolute value); c0 represents the plateau

  16. Sulfate reduction and oxic respiration in marine sediments: implications for organic carbon preservation in euxinic environments

    NASA Technical Reports Server (NTRS)

    Canfield, D. E.; DeVincenzi, D. L. (Principal Investigator)

    1989-01-01

    Compilations have been made of sulfate reduction rates and oxic respiration rates over the entire range of marine sedimentation rates, and sedimentary environments, including several euxinic sites. These data show, consistent with the findings of Jorgensen (1982, Nature, 296, 643-645), that sulfate reduction and oxic respiration oxidize equal amounts of organic carbon in nearshore sediments. As sedimentation rates decrease, oxic respiration, becomes progressively more important, and in deep-sea sediments 100-1000 times more organic carbon is oxidized by oxic respiration than by sulfate reduction. By contrast, nearly as much organic carbon is oxidized by sulfate reduction in euxinic sediments as is oxidized by the sum of sulfate reduction and oxic respiration in normal marine sediments of similar deposition rate. This observation appears at odds with the enhanced preservation of organic carbon observed in euxinic sediments. However, only small reductions in (depth-integrated) organic carbon decomposition rates (compared to normal marine) are required to give both high organic carbon concentrations and enhanced carbon preservation in euxinic sediments. Lower rates of organic carbon decomposition (if only by subtle amounts) are explained by the diminished ability of anaerobic bacteria to oxidize the full suite of sedimentary organic compounds.

  17. EXPLORATORY ANALYSIS OF THE EFFECTS OF PARTICULATE CHARACTERISTICS ON THE VARIATION IN PARTITIONING OF NONPOLAR ORGANIC CONTAMINANTS TO MARINE SEDIMENTS

    EPA Science Inventory

    The partitioning of nonpolar organic contaminants to marine sediments is considered to be controlled by the amount of organic carbon present. However, several studies propose that other characteristics of sediments may affect the partitioning of contaminants. For this exploratory...

  18. Evaluation of the Polyethylene Reverse Sampler as a Dosing System in Marine Phase II Whole Sediment Toxicity Identification Evaluations (TIEs)

    EPA Science Inventory

    Contaminated marine sediments can cause acute and chronic impairments to benthic organisms. Nonionic organic contaminants (NOCs) are often a primary cause of impairment. Toxicity Identification Evaluations (TIEs) are used to identify chemicals causing toxicity in sediments. Ph...

  19. Sediment toxicity to a marine infaunal amphipod: cadmium and its interaction with sewage sludge

    SciTech Connect

    Swartz, R.C.; Ditsworth, G.R.; Schults, D.W.; Lamberson, J.O.

    1985-01-01

    The acute toxicity of cadmium to the marine infaunal amphipod, Rhepoxynius abronius, was determined separately in sediment and seawater. Most cadmium added to test sediment was bound to particles and less than 5% was dissolved in interstitial water. The LC50 based on cadmium concentration in interstitial water was similar to the LC50 based on cadmium concentration in seawater without sediment. Cadmium in interstitial water, rather than that bound to particles, therefore appears responsible for acute sediment toxicity to this species. The addition of small quantities of sewage sludge or an increase in the proportion of the fine fraction of sediment particles significantly reduced the toxicity of cadmium in sediment. Binding of cadmium by sediment particles may explain the presence of phoxocephalid amphipods at sites where sewage and metal pollution occur together.

  20. Germanium isotopic variations in igneous rocks and marine sediments

    NASA Astrophysics Data System (ADS)

    Rouxel, Olivier; Galy, Albert; Elderfield, Henry

    2006-07-01

    A new technique for the precise and accurate determination of Ge stable isotope compositions has been developed and applied to silicate rocks and biogenic opal. The analyses were performed using a continuous flow hydride generation system coupled to a MC-ICPMS. Samples have been purified through anion- and cation-exchange resins to separate Ge from matrix elements and eliminate potential isobaric interferences. Variations of 74Ge/ 70Ge ratios are expressed as δ74Ge values relative to our internal standard and the long-term external reproducibility of the data is better than 0.2‰ for sample size as low as 15 ng of Ge. Data are presented for igneous and sedimentary rocks, and the overall variation is 2.4‰ in δ74Ge, representing 12 times the uncertainty of the measurements and demonstrating that the terrestrial isotopic composition of Ge is not unique. Co-variations of 74Ge/ 70Ge, 73Ge/ 70Ge and 72Ge/ 70Ge ratios follow a mass-dependent behaviour and imply natural isotopic fractionation of Ge by physicochemical processes. The range of δ74Ge in igneous rocks is only 0.25‰ without systematic differences among continental crust, oceanic crust or mantle material. On this basis, a Bulk Silicate Earth reservoir with a δ74Ge of 1.3 ± 0.2‰ can be defined. In contrast, modern biogenic opal such as marine sponges and authigenic glauconite displayed higher δ74Ge values between 2.0‰ and 3.0‰. This suggests that biogenic opal may be significantly enriched in light isotopes with respect to seawater and places a lower bound on the δ74Ge of the seawater to +3.0‰.This suggests that seawater is isotopically heavy relative to Bulk Silicate Earth and that biogenic opal may be significantly fractionated with respect to seawater. Deep-sea sediments are within the range of the Bulk Silicate Earth while Mesozoic deep-sea cherts (opal and quartz) have δ74Ge values ranging from 0.7‰ to 2.0‰. The variable values of the cherts cannot be explained by binary mixing

  1. Natural Organobromine in Marine Sediments: New Evidence of Biogeochemical Br Cycling

    SciTech Connect

    A Leri; J Hakala; M Marcus; A Lanzirotti; C Reddy; S Myneni

    2011-12-31

    Organobromine (Br{sub org}) compounds, commonly recognized as persistent, toxic anthropogenic pollutants, are also produced naturally in terrestrial and marine systems. Several enzymatic and abiotic bromination mechanisms have been identified, as well as an array of natural Br{sub org} molecules associated with various marine organisms. The fate of the carbon-bromine functionality in the marine environment, however, remains largely unexplored. Oceanographic studies have noted an association between bromine (Br) and organic carbon (C{sub org}) in marine sediments. Even so, there has been no direct chemical evidence that Br in the sediments exists in a stable form apart from inorganic bromide (Br{sub inorg}), which is widely presumed conservative in marine systems. To investigate the scope of natural Br{sub org} production and its fate in the environment, we probed Br distribution and speciation in estuarine and marine sediments using in situ X-ray spectroscopy and spectromicroscopy. We show that Br{sub org} is ubiquitous throughout diverse sedimentary environments, occurring in correlation with C{sub org} and metals such as Fe, Ca, and Zn. Analysis of sinking particulate carbon from the seawater column links the Br{sub org} observed in sediments to biologically produced Br{sub org} compounds that persist through humification of natural organic matter (NOM). Br speciation varies with sediment depth, revealing biogeochemical cycling of Br between organic and inorganic forms as part of the burial and degradation of NOM. These findings illuminate the chemistry behind the association of Br with Corg in marine sediments and cast doubt on the paradigmatic classification of Br as a conservative element in seawater systems.

  2. Ratio of the concentration of anthraquinone to anthracene in coastal marine sediments.

    PubMed

    McKinney, R A; Pruell, R J; Burgess, R M

    1999-04-01

    The ratio of the concentration of the oxidation product anthraquinone to that of its parent polycyclic aromatic hydrocarbon anthracene is reported for several coastal marine sediments. The ratio ranges from 0.317 in a highly contaminated industrialized harbor to 2.81 in a remote, less contaminated site. We hypothesize that differences in this ratio result from the input source of PAHs, with input from atmospheric deposition at remote sites resulting in a predominance of anthraquinone (ratio > 1), and direct discharge to highly contaminated industrialized harbors resulting in a predominance of anthracene (ratio < 1). To support this hypothesis, the fate of anthracene in the marine environment was investigated with respect to conversion to its oxidation product, anthraquinone. Once associated with sediments, anthracene is believed to be relatively persistent; however, it can potentially be subjected to oxidation via biological (microbial degradation) and chemical (chemical oxidation and photooxidation) processes. An assessment of the extent of oxidation of anthracene associated with sediments was conducted both under conditions simulating those found in the marine environment and under rigorous conditions by exposure to UV radiation. Results of this study show that while anthracene associated with marine sediments does not readily undergo oxidation to anthraquinone under conditions normally encountered in the marine environment, under extreme conditions anthracene is photooxidized by exposure to UV radiation. The extent of oxidation is influenced by sediment characteristics such as percent organic carbon, humic acid content and sediment surface area. The relative stability of anthracene under normal conditions may help to validate the use of the anthraquinone to anthracene ratio in marine sediments as an environmental marker of contaminant source.

  3. The use of the Novosol process for the treatment of polluted marine sediment.

    PubMed

    Zoubeir, Lafhaj; Adeline, Saliceto; Laurent, Cohen Solal; Yoann, Coudray; Truc, Huynh Trung; Benoît, Le Guen; Federico, Anguoni

    2007-09-30

    The work presented in this article concerns polluted marine sediments. The article is divided into three parts. The first part discusses existing industrial procedures of treatment. The second part introduces the Novosol((R)) process, which was used for the treatment of polluted marine sediments. This process is based on the stabilization of heavy metals in the solid matrix by phosphatation and the destruction of organic matter by calcination. Finally, after a comparison had been made between environmental results obtained on both polluted marine sediments and inert ones, treated sediments were introduced in the production of clay bricks. The results obtained show that the Novosol process leads to the immobilization of most heavy metals and can be considered as an efficient tool for the stabilisation of polluted marine sediment. Thus, the results of physical and mechanical tests as compressive strength and water absorption indicate that performances obtained were comparable to standard brick values. These results confirm that, once treated, polluted sediments can be recycled.

  4. The use of the Novosol process for the treatment of polluted marine sediment.

    PubMed

    Zoubeir, Lafhaj; Adeline, Saliceto; Laurent, Cohen Solal; Yoann, Coudray; Truc, Huynh Trung; Benoît, Le Guen; Federico, Anguoni

    2007-09-30

    The work presented in this article concerns polluted marine sediments. The article is divided into three parts. The first part discusses existing industrial procedures of treatment. The second part introduces the Novosol((R)) process, which was used for the treatment of polluted marine sediments. This process is based on the stabilization of heavy metals in the solid matrix by phosphatation and the destruction of organic matter by calcination. Finally, after a comparison had been made between environmental results obtained on both polluted marine sediments and inert ones, treated sediments were introduced in the production of clay bricks. The results obtained show that the Novosol process leads to the immobilization of most heavy metals and can be considered as an efficient tool for the stabilisation of polluted marine sediment. Thus, the results of physical and mechanical tests as compressive strength and water absorption indicate that performances obtained were comparable to standard brick values. These results confirm that, once treated, polluted sediments can be recycled. PMID:17459577

  5. Degradation of dissolved organic monomers and short-chain fatty acids in sandy marine sediment by fermentation and sulfate reduction

    NASA Astrophysics Data System (ADS)

    Valdemarsen, Thomas; Kristensen, Erik

    2010-03-01

    The decay of a wide range of organic monomers (short-chain volatile fatty acids (VFA's), amino acids, glucose and a pyrimidine) was studied in marine sediments using experimental plug flow-through reactors. The reactions were followed in the presence and absence of 10 mM SO 42-. Degradation stoichiometry of individual monomers (inflow concentration of 6 mM organic C) was traced by measuring organic (VFA's, amino acids) and inorganic (CO 2, NH 4+, SO 42-) compounds in the outflow. Fermentation of amino acids was efficient and complete during passage through anoxic sediment reactors. Aliphatic amino acids (alanine, serine and glutamate) were primarily recovered as CO 2 (24-34%), formate (3-22%) and acetate (41-83%), whereas only ˜1/3 of the aromatic amino acid (tyrosine) was recovered as CO 2 (13%) and acetate (20%). Fermentation of glucose and cytosine was also efficient (78-86%) with CO 2 (30-35%), formate (3%) and acetate (28-33%) as the primary products. Fermentation of VFA's (acetate, propionate and butyrate), on the other hand, appeared to be product inhibited. The presence of SO 42- markedly stimulated VFA degradation (29-45% efficiency), and these compounds were recovered as CO 2 (17% for butyrate to 100% for acetate) and acetate (51% and 82% for propionate and butyrate, respectively). When reaction stoichiometry during fermentation is compared with compound depletion during sulfate reduction, the higher proportion CO 2 recovery is consistent with lower acetate and formate accumulation. Our results therefore suggest that fermentation reactions mediate the initial degradation of added organic compounds, even during active sulfate reduction. Fermentative degradation stoichiometry also suggested significant H 2 production, and >50% of sulfate reduction appeared to be fuelled by H 2. Furthermore, our results suggest that fermentation was the primary deamination step during degradation of the amino acids and cytosine.

  6. Algal blooms and "Marine snow": Mechanisms that enhance preservation of organic carbon in ancient fine-grained sediments

    USGS Publications Warehouse

    Macquaker, J.H.S.; Keller, M.A.; Davies, S.J.

    2010-01-01

    Combined petographic and geochemical methods are used to investigate the microfabrics present in thin sections prepared from representative organic carbon-rich mudstones collected from three successions (the Kimmeridge Clay Formation, the Jet Rock Member of the Whitby Mudstone Formation, and the pebble shale and Hue Shale). This study was initiated to determine how organic carbon-rich materials were being delivered to the sediment-water interface, and what happened to them after deposition, prior to deep burial. Analyses of the fabrics present shows that they exhibit many common attributes. In particular they are all: (1) highly heterogeneous on the scale of a thin section, (2) organized into thin beds (< 10 mm thick) composed mainly of mineral mixtures of fine-grained siliciclastic detritus and carbonate materials, and (3) contain significant concentrations of organic carbon, much of which is organized into laminasets that contain abundant organomineralic aggregates and pellets. In addition, framboidal pyrite (range of sizes from < 20 urn to < 1 ??m) and abundant agglutinated foraminifers are present in some units. The individual beds are commonly sharp-based and overlain by thin, silt lags. The tops of many of the beds have been homogenized and some regions of the pelleted laminasets contain small horizontal burrows. The organomineralic aggregates present in these mudstones are interpreted to be ancient examples of marine snow. This marine snow likely formed in the water column, particularly during phytoplankton blooms, and was then transported rapidly to the seafloor. The existence of the thin beds with homogenized tops and an in-situ infauna indicates that between blooms there was sufficient oxygen and time for a mixed layer to develop as a result of sediment colonization by diminutive organisms using either aerobic or dysaerobic metabolic pathways. These textures suggest that the constituents of these mudstones were delivered neither as a continuous rain of

  7. Transformation of marine sediment to paddy soil: Primary marine, lacustrine, and land plant lipids

    NASA Astrophysics Data System (ADS)

    Mueller-Niggemann, Cornelia; Cao, Zhihong; Schwark, Lorenz

    2010-05-01

    More than fifty percent of the world's population feeds on rice. The continuous population increase and urban sprawl leads to an ever-increasing demand for new rice cultivation area, in particular China. For centuries suitable coastal areas in China have been exploited for land reclamation, i.e. conversion of coastal marine and lacustrine marshlands into rice paddy fields. Flooded rice paddies are considered one of the major biogenic sources of methane into the atmospheric. Methane is thought to be about 30 times more efficient as greenhouse gas, when compared to carbon dioxide. Overall, rice fields are assumed to contribute app. 10-25% to global CH4 production. It is thus paramount importance to study the effects of increasing rice cultivation and land reclamation in China. For global carbon cycle investigation, it is crucial whether paddy soils, due to their large extent and higher carbon turnover, serve as carbon (CO2) sinks or sources. Here we present results from a chronosequence study of paddy soils with different and well known starting dates of cultivation, in the Zhejiang province (Yangtze River delta) by land reclamation through the building of protective dikes over the past 2000 years. Two end members of natural sediments subjected to land reclamation, a marine tidal mudflat in the Yangtze delta and a coastal lake, represent the substrate on which the paddy soil evolution started. Dike systems were constructed 2000, 1000, 700, 300, 100, and 50 years before present. We are thus able to follow the evolution of rice paddy soils developed on marine sediments using eight well defined tie-points. This chronosequence is then used for assessing the relative proportion of primary marine or lacustrine organic matter preserved in present day soils and to identify the amount and composition of organic matter added since cultivation started. Paddy soil management introduces rice plants debris and exudates as well as rice-associated microbial biomass (covered in a

  8. Natural thorium isotopes in marine sediment core off Labuan port

    SciTech Connect

    Hafidz, B. Y.; Asnor, A. S.; Terence, R. C.; Mohamed, C. A. R.

    2014-02-12

    Sediment core was collected from Labuan port and analyzed to determine the radioactivity of thorium (Th) isotopes. The objectives of this study are to determine the possible sources of Th isotopes at Labuan port and estimates the sedimentation rate based on {sup 228}Th/{sup 232}Th model. The results suggest the {sup 230}Th and {sup 232}Th might be originated from terrestrial sedimentary rock while {sup 228}Th originated by authigenic origin. High ratio value of {sup 230}Th/{sup 232}Th detected at the top surface sediment indicates the increasing of {sup 230}Th at the recent years which might be contributed from the anthropogenic sources. The sedimentation rate of core sediment from Labuan Port was successfully estimated by using {sup 228}Th/{sup 232}Th model. The result show high sedimentation rate with 4.67 cm/year indicates rapid deposition occurred at this study area due to the high physical activity at the Labuan port. By assume the constant sedimentation rate at this area; we estimated the age of 142 cm core sediment obtained from Labuan port is 32 years started from 1981 to 2012. This chronology will be used in forthcoming research to investigate the historical profile of anthropogenic activities affecting the Labuan port.

  9. The microbial nitrogen cycling potential is impacted by polyaromatic hydrocarbon pollution of marine sediments

    PubMed Central

    Scott, Nicole M.; Hess, Matthias; Bouskill, Nick J.; Mason, Olivia U.; Jansson, Janet K.; Gilbert, Jack A.

    2014-01-01

    During hydrocarbon exposure, the composition and functional dynamics of marine microbial communities are altered, favoring bacteria that can utilize this rich carbon source. Initial exposure of high levels of hydrocarbons in aerobic surface sediments can enrich growth of heterotrophic microorganisms having hydrocarbon degradation capacity. As a result, there can be a localized reduction in oxygen potential within the surface layer of marine sediments causing anaerobic zones. We hypothesized that increasing exposure to elevated hydrocarbon concentrations would positively correlate with an increase in denitrification processes and the net accumulation of dinitrogen. This hypothesis was tested by comparing the relative abundance of genes associated with nitrogen metabolism and nitrogen cycling identified in 6 metagenomes from sediments contaminated by polyaromatic hydrocarbons from the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico, and 3 metagenomes from sediments associated with natural oil seeps in the Santa Barbara Channel. An additional 8 metagenomes from uncontaminated sediments from the Gulf of Mexico were analyzed for comparison. We predicted relative changes in metabolite turnover as a function of the differential microbial gene abundances, which showed predicted accumulation of metabolites associated with denitrification processes, including anammox, in the contaminated samples compared to uncontaminated sediments, with the magnitude of this change being positively correlated to the hydrocarbon concentration and exposure duration. These data highlight the potential impact of hydrocarbon inputs on N cycling processes in marine sediments and provide information relevant for system scale models of nitrogen metabolism in affected ecosystems. PMID:24723913

  10. A statistical approach to the interpretation of aliphatic hydrocarbon distributions in marine sediments

    USGS Publications Warehouse

    Rapp, J.B.

    1991-01-01

    Q-mode factor analysis was used to quantitate the distribution of the major aliphatic hydrocarbon (n-alkanes, pristane, phytane) systems in sediments from a variety of marine environments. The compositions of the pure end members of the systems were obtained from factor scores and the distribution of the systems within each sample was obtained from factor loadings. All the data, from the diverse environments sampled (estuarine (San Francisco Bay), fresh-water (San Francisco Peninsula), polar-marine (Antarctica) and geothermal-marine (Gorda Ridge) sediments), were reduced to three major systems: a terrestrial system (mostly high molecular weight aliphatics with odd-numbered-carbon predominance), a mature system (mostly low molecular weight aliphatics without predominance) and a system containing mostly high molecular weight aliphatics with even-numbered-carbon predominance. With this statistical approach, it is possible to assign the percentage contribution from various sources to the observed distribution of aliphatic hydrocarbons in each sediment sample. ?? 1991.

  11. Microbial activity in deep marine sediments: does pressure make the difference?

    NASA Astrophysics Data System (ADS)

    Picard, Aude; Ferdelman, Timothy G.

    2012-07-01

    We attempted to evaluate the effects of high hydrostatic pressure on microbial heterotrophic activity in deep marine sediments from the Atlantic Ocean. We investigated the potential respiration rates (acetate/glucose oxidation to CO2) in oxic sediments recovered from up to ~4500 m water depth. Incubations were performed at ambient pressure and at near in situ pressure (~40-45 MPa) with sediments stored at ambient pressure and at in situ pressure. Potential respiration rates in sediments stored at ambient pressure were lower when measured at in situ pressure than when measured at ambient pressure, independently of the substrate used. It appears that the pressure of storage is critical since potential respiration rates of sediments stored at in situ pressure were higher than in the counterpart sediments stored at ambient pressure.

  12. Chronic effects of organochlorine exposure in sediment to the marine polychaete Neanthes arenaceodentata

    SciTech Connect

    Murdoch, M.H.; Chapman, P.M.; Johns, D.M.; Paine, M.D.

    1997-07-01

    Organisms exposed to organochlorinated compounds in sediments are likely to suffer chronic rather than acute effects. Thus, acute toxicity tests are unlikely to truly assess their potential impact. A 120-d toxicity test was designed to assess the impact of polychlorinated biphenyl on the marine polychaete Neanthes arenacedodentata. A two-tiered approach was used: Tier 1 involved reference sediment spiked with a range of concentrations of the organochlorine bracketing the concentrations found in natural sediments, and tier 2 involved field sediments collected from a coastal area contaminated with high concentrations of the same organochlorine. Testing measured a number of endpoints, including survival, growth, and reproduction. Survival and growth were unaffected in either tier by any of the test sediments. Reproductive endpoints, however, were depressed in both tiers relative to the reference sediment.

  13. Decoupling of the Carbon Cycle during Ocean Anoxic Event-2

    NASA Astrophysics Data System (ADS)

    Eldrett, J.; Bergman, S. C.; Minisini, D.

    2013-12-01

    The Cenomanian to Turonian Boundary transition (95-93 Ma) represents one of the most profound global perturbations in the carbon cycle of the last 140 million years. This interval is characterized by widespread deposition of organic-rich fine-grained sediment marked by a globally recognised positive carbon isotope excursion (CIE) reflecting the widespread removal of 12C-enriched organic matter in marine sediments under global anoxic conditions. However, the exact timing and trigger of this inferred global phenomenon, termed Oceanic Anoxic Event-2 is still debated, with recent studies showing diachroneity between the deposition of the organic-rich sediment and the CIE, and conflicting interpretations on detailed redox analyses in several of these inferred anoxic settings. Here we present the first evidence for widespread and persistent oxygenation during OAE-2 based primarily on the distribution of redox-sensitive trace metals preserved in sediments from the Eagle Ford Formation, Western Interior Seaway of North America. We generated a δ13C curve which indicates an earlier initiation of the CIE in Texas compared to the Global Stratotype and Point Section at Pueblo, Colorado. Our data also indicate anoxic-euxinic conditions in the mid-late Cenomanian, but improved bottom-water oxygenation prior to and during the CIE, corroborated by increased bioturbation, abundance of benthic foraminifera and reduced total organic carbon values. Trace metal enrichments support large volumes of mafic volcanism possibly from the High Arctic Large Igneous Province (LIP), which occur during peak bottom-water oxygenation and a plateau in δ13Corg values and does not immediately precede the Cenomanian-Turonian CIE, as previously stated. This suggests that the emplacement of a LIP was not the primary trigger of the OAE-2 event. It is also unlikely that bottom-water oxygenation was promoted by the introduction of volcanogenic Fe inhibiting sulfate reduction, as the depletion in redox

  14. Development and application of a marine sediment porewater toxicity test using algal spores

    SciTech Connect

    Hooten, R.; Carr, R.S.

    1995-12-31

    An acute pore water toxicity test protocol using germination and growth of marine macroalgae as endpoints was developed to indicate the presence of toxic compounds in marine/estuarine and sediment porewater samples. Zoospores collected from Ulva fasciata and U. lactuca were used as test organisms. Preliminary results with sodium dodecyl sulfate (SDS, a reference toxicant) indicate that zoospores germination and growth of embryonic gametophytes are as sensitive as the sea urchin fertilization and embryological development toxicity tests. Algal germination and growth data for copper, mercury and other metals will be presented. The results of tests utilizing this algal assay with sediment pore water from contaminated sediments will be compared with more traditional sediment toxicity test methods.

  15. Degradation of PCBs in a marine sediment treated with ionizing and UV radiation.

    PubMed

    Poster, Dianne L; Chaychian, Mahnaz; Neta, Pedatsur; Huie, Robert E; Silverman, Joseph; Al-Sheikhly, Mohamad

    2003-09-01

    Radiolytic (electron beam) and photolytic (ultraviolet, UV) dechlorination of polychlorinated biphenyls (PCBs) in a marine sediment are described. Samples of a PCB-laden marine sediment, Standard Reference Material (SRM) 1944, NewYork/New Jersey Waterway Sediment, have been mixed with aqueous alcohol solutions and irradiated with an electron beam or photolyzed. Additives, such as alcohol, enhance the radiolytic yield and PCB dechlorination. In the electron beam irradiated samples, the concentrations of 29 PCB congeners decrease with irradiation dose. At the highest dose (500 kGy), the total concentration of PCBs is decreased by 83%. Photolysis leads to little dechlorination, but photolysis with added triethylamine leads to dechlorination (about 60%). It is likely that photolysis under optimal conditions (other additives, exposure time) may be as effective as electron beam radiolysis for the dechlorination of PCBs in sediment.

  16. Development of marine sediment toxicity identification evaluation methods using Strongylocentrotus purpuratus, Mytilus edulis, and Eohaustorius estuarius

    SciTech Connect

    Wortham, G.; Cotsifas, J.S.; Taberski, K.; Hansen, S.R.

    1994-12-31

    Widespread sediment toxicity, including ``clean`` reference sites, dictates that the causes of toxicity in sediments be determined. Toxicity Identification Evaluations (TIE) are useful tools in characterizing compounds responsible for toxicity, but were unavailable for sediment samples. TIE methods were developed for sediment porewater and included the following components: determination of an appropriate porewater extraction process; control TIE tests using marine water and porewater evaluating species sensitivities to the fractionation procedures; validation experiments investigating the removal efficiencies of organics using C18 solid phase extraction, and metals chelation using EDTA and STS; spiking experiments to determine the effectiveness of the TIE procedure in identifying multiple toxicants. The authors determined that fractionation procedures could be applied to both marine water and porewater using S. purpuratus, M. edulis and E. estuarius as biological detectors.

  17. The Scientific and Societal Need for Accurate Global Remote Sensing of Marine Suspended Sediments

    NASA Technical Reports Server (NTRS)

    Acker, James G.

    2006-01-01

    Population pressure, commercial development, and climate change are expected to cause continuing alteration of the vital oceanic coastal zone environment. These pressures will influence both the geology and biology of the littoral, nearshore, and continental shelf regions. A pressing need for global observation of coastal change processes is an accurate remotely-sensed data product for marine suspended sediments. The concentration, delivery, transport, and deposition of sediments is strongly relevant to coastal primary production, inland and coastal hydrology, coastal erosion, and loss of fragile wetland and island habitats. Sediment transport and deposition is also related to anthropogenic activities including agriculture, fisheries, aquaculture, harbor and port commerce, and military operations. Because accurate estimation of marine suspended sediment concentrations requires advanced ocean optical analysis, a focused collaborative program of algorithm development and assessment is recommended, following the successful experience of data refinement for remotely-sensed global ocean chlorophyll concentrations.

  18. Diatoms respire nitrate to survive dark and anoxic conditions

    PubMed Central

    Kamp, Anja; de Beer, Dirk; Nitsch, Jana L.; Lavik, Gaute; Stief, Peter

    2011-01-01

    Diatoms survive in dark, anoxic sediment layers for months to decades. Our investigation reveals a correlation between the dark survival potential of marine diatoms and their ability to accumulate NO3− intracellularly. Axenic strains of benthic and pelagic diatoms that stored 11–274 mM NO3− in their cells survived for 6–28 wk. After sudden shifts to dark, anoxic conditions, the benthic diatom Amphora coffeaeformis consumed 84–87% of its intracellular NO3− pool within 1 d. A stable-isotope labeling experiment proved that 15NO3− consumption was accompanied by the production and release of 15NH4+, indicating dissimilatory nitrate reduction to ammonium (DNRA). DNRA is an anaerobic respiration process that is known mainly from prokaryotic organisms, and here shown as dissimilatory nitrate reduction pathway used by a eukaryotic phototroph. Similar to large sulfur bacteria and benthic foraminifera, diatoms may respire intracellular NO3− in sediment layers without O2 and NO3−. The rapid depletion of the intracellular NO3− storage, however, implies that diatoms use DNRA to enter a resting stage for long-term survival. Assuming that pelagic diatoms are also capable of DNRA, senescing diatoms that sink through oxygen-deficient water layers may be a significant NH4+ source for anammox, the prevalent nitrogen loss pathway of oceanic oxygen minimum zones. PMID:21402908

  19. Interaction of marine and fluvial clastic sedimentation, central Italy, Tyrrhenian coast

    SciTech Connect

    Evangelista, S.; Full, W.E.; Tortora, P.

    1989-03-01

    An integrated approach was used to study the interaction of fluvial, beach, and marine processes on sedimentation at the west-central coast of Italy along the Tyrrhenian Sea. The study area, 120 km northwest of Rome, is bounded on the north by Mt. Argentario, on the east by Pleistocene volcanics, on the south by the St. Augustine River, and on the west by the 50-mn bathymetric isopleth. The primary tools used included field work, textural analysis, high-resolution marine seismic, SEM, and Fourier shape analysis. Field work revealed incised streams, potentially relict beach ridges and lagoons, and relatively steep nearshore marine slopes in the northern portions of the study area. The result of the shape analysis performed on 56 samples was the definition of four end members. Each end member reflects a sedimentation process. Three end members were directly associated with fluvial sedimentation, and the fourth reflected marine processes. The seismic data along with the SEM analysis strongly supported the interpretation of four processes that dominate the recent sedimentation history. The sand interpreted to be associated with marine processes was found to represent the smoothest end member. SEM analysis suggests that the smoothing is not due to abrasion but to plastering associated with biologic processes (digestion.) and/or with silica precipitation associated with clay alteration at the freshwater/saltwater interface.

  20. Formation of natural gas hydrates in marine sediments 1. Conceptual model of gas hydrate growth conditioned by host sediment properties

    USGS Publications Warehouse

    Clennell, M.B.; Hovland, M.; Booth, J.S.; Henry, P.; Winters, W.J.

    1999-01-01

    The stability of submarine gas hydrates is largely dictated by pressure and temperature, gas composition, and pore water salinity. However, the physical properties and surface chemistry of deep marine sediments may also affect the thermodynamic state, growth kinetics, spatial distributions, and growth forms of clathrates. Our conceptual model presumes that gas hydrate behaves in a way analogous to ice in a freezing soil. Hydrate growth is inhibited within fine-grained sediments by a combination of reduced pore water activity in the vicinity of hydrophilic mineral surfaces, and the excess internal energy of small crystals confined in pores. The excess energy can be thought of as a "capillary pressure" in the hydrate crystal, related to the pore size distribution and the state of stress in the sediment framework. The base of gas hydrate stability in a sequence of fine sediments is predicted by our model to occur at a lower temperature (nearer to the seabed) than would be calculated from bulk thermodynamic equilibrium. Capillary effects or a build up of salt in the system can expand the phase boundary between hydrate and free gas into a divariant field extending over a finite depth range dictated by total methane content and pore-size distribution. Hysteresis between the temperatures of crystallization and dissociation of the clathrate is also predicted. Growth forms commonly observed in hydrate samples recovered from marine sediments (nodules, and lenses in muds; cements in sands) can largely be explained by capillary effects, but kinetics of nucleation and growth are also important. The formation of concentrated gas hydrates in a partially closed system with respect to material transport, or where gas can flush through the system, may lead to water depletion in the host sediment. This "freeze-drying" may be detectable through physical changes to the sediment (low water content and overconsolidation) and/or chemical anomalies in the pore waters and metastable

  1. Development of a toxicity identification evaluation procedure for characterizing metal toxicity in marine sediments

    SciTech Connect

    Burgess, R.M.; Cantwell, M.G.; Pelletier, M.C.; Ho, K.T.; Serbst, J.R.; Cook, H.F.; Kuhn, A.

    2000-04-01

    A multiagency effort is underway to develop whole sediment toxicity identification evaluation (TIE) methods. Whole sediment TIE methods will be critical tools for characterizing toxicity at hazardous waste sites and in the conduct of environmental risk assessments. The research approach is based on the predominance of three classes of toxicants in sediments: ammonia, nonpolar organic chemicals, and metals. Here the authors describe a procedure for characterizing acute toxicity caused by metals in whole marine sediments. The procedure involves adding a chelating resin to sediments, resulting in the sequestration of bioavailable metal while not stressing testing organisms. Within the testing chambers, the presence of resin resulted in statistically significant reductions in the overlying and interstitial water concentrations of five metals (cadmium, copper, nickel, lead, and zinc) generally by factors of 40 and 200. Toxicity to both the amphipod Ampelisca abdita and mysid Americamysis bahia (formerly Mysidopsis bahia) of sediments spiked with the five metals was decreased by approximately a factor of four when resin was present. While very effective at reducing the concentrations and toxicity of metals, the resin has only minor ameliorative effects on the toxicity of ammonia and a representative nonpolar toxicant (Endosulfan). Resin and accumulated metal were easily isolated from the testing system following exposures allowing for the initiation of phase II TIE (identification) procedures. This procedure using the addition of a chelating resin provides an approach for determining the importance of metals to the toxicity of marine sediments. Work is continuing to validate the method with environmentally contaminated sediments.

  2. An improved electroelution method for separation of DNA from humic substances in marine sediment DNA extracts.

    PubMed

    Kallmeyer, Jens; Smith, David C

    2009-07-01

    We present a method for the rapid and simple extraction of DNA from marine sediments using electroelution. It effectively separates DNA from compounds, including humic substances, that interfere with subsequent DNA quantification and amplification. After extraction of the DNA from the sediment into an aqueous solution, the crude sample is encased in 2% agarose gel and exposed to an electrical current, which draws the DNA out of the gel into a centrifugal filter vial. After electroelution, the sample is centrifuged to remove contaminants sediment and is particularly useful for sediments containing low biomass such as deeply buried marine sediments. It works with both organic-rich and -poor sediment, as well as with sediment where calcium carbonate is abundant and sediment where it is limited; consequently, adjustment of protocols is unnecessary for samples with very different organic and mineral contents.

  3. Sulfur reduction in sediments of marine and evaporite environments

    NASA Technical Reports Server (NTRS)

    Klug, M. J.; Boston, P.; Francois, R.; Gyure, R. A.; Javor, B.; Tribble, G.; Vairavamurthy, A.

    1985-01-01

    Transformations of sulfur in sediments of ponds ranging in salinities from that of normal seawater to those of brines saturated with sodium chloride were examined. The chemistry of the sediment and pore waters were focused on with emphasis on the fate of sulfate reduction. The effects of increasing salinity on both forms of sulfur and microbial activity were determined. A unique set of chemical profiles and sulfate-reducing activity was found for the sediments of each of the sites examined. The quantity of organic matter in the salt pond sediments was significantly greater than that occurring in the adjacent intertidal site. The total quantitative and qualitative distribution of volatile fatty acids was also greater in the salt ponds. Volatile fatty acids increased with salinity.

  4. Ecotoxicological sediment evaluations in marine aquaculture areas of Chile.

    PubMed

    Rudolph, Anny; Medina, Paulina; Urrutia, Carolina; Ahumada, Ramón

    2009-08-01

    Given its geographic characteristics, the southern Chilean fjord area is subjected to growing environmental pressure from the development of diverse forms of aquaculture (i.e., fish, algae, shellfish). The sediments accumulate substances as a natural sink, and ecotoxicology assays offer a reliable and robust proxy for sediment quality analyses. This study's objective was to establish a mid-range toxicity base line for the sediments in the region by applying a battery of non-specific ecotoxicological assays. Sediment samples (28) were collected in the channels and fjords studied during the CIMAR-Fiordos 11 cruise (July 2005). The sediments were evaluated using different species endemic to the eastern Pacific as targets: Ampelisca araucana, Tisbe longicornis, Arbacia spatuligera, and Dunaliella tertiolecta. The conditions for each assay were reported previously. Of the four species used as ecotoxicological tools, only D. tertiolecta differed significantly from the control group (negative) in terms of its growth. This difference could be attributed to nutrient enrichment. In general, we concluded that, although local changes occurred in the sediments, the mesoscale magnitude of the ecotoxicological alterations was small. Nonetheless, a surveillance program should be implemented that would allow us to follow-up and analyze the changes that are taking place in the systems on broader scales of time and space. PMID:18633720

  5. Phototoxic evaluation of marine sediments collected from a PAH-contaminated site.

    PubMed

    Boese, B L; Ozretich, R J; Lamberson, J O; Cole, F A; Swartz, R C; Ferraro, S P

    2000-04-01

    The phototoxicity potential of PAH-contaminated field sediment was evaluated and compared to standard sediment toxicity test results. Marine sediments were collected from 30 sites along a presumed PAH sediment pollution gradient in Elliot Bay, WA. Standard 10-day acute and 28-day chronic sediment toxicity tests were conducted with the infaunal amphipods Rhepoxynius abronius and Leptocheirus plumulosus using mortality and the ability to rebury as endpoints. The survivors of these tests were then subjected to 1-h exposures to UV radiation with mortality and reburial again determined. The most highly toxic sediments identified in these experiments were evaluated further for toxicity and phototoxicity by serially diluting them with uncontaminated sediment and repeating the toxicity tests. Standard 10-day toxicity test results indicated that over 70% of the sites sampled in Elliot Bay exhibited measurable toxicity with nine sites being highly toxic to both species of amphipods. Results of standard 28-day chronic sediment toxicity tests were similar. In contrast, almost all of the sites were found to be highly phototoxic. Results indicated that exposure to UV increased toxicity five- to eightfold. This suggests that standard toxicity tests underestimate the potential ecological risk of PAH-contaminated sediments in animals exposed to sunlight. However, only when PAH contamination was between 0.05 and 1.0 toxic units would conducting a phototoxicity evaluation add information to that gained from conducting a standard sediment toxicity test alone.

  6. Concurrent low- and high-affinity sulfate reduction kinetics in marine sediment

    NASA Astrophysics Data System (ADS)

    Harder Tarpgaard, Irene; Røy, Hans; Jørgensen, Bo Barker

    Bacterial sulfate reduction in marine sediments generally occurs in the presence of high millimolar concentrations of sulfate. Published data indicate that low sulfate concentrations may limit sulfate reduction rates below 0.2-2 mM. Yet, high sulfate reduction rates occur in the 1-100 μM range in freshwater sediments and at the sulfate-methane transition in marine sediments. Through a combination of 35S-tracer experiments, including initial velocity experiments and time course experiments, we searched for different sulfate affinities in the mixed community of sulfate reducers in a marine sediment. We supported the radiotracer experiments with a highly sensitive ion chromatographic technique for sulfate with a detection limit of 0.15 μM SO 42- in marine pore water. Our results showed that high and low affinities for sulfate co-occur and that the applied experimental approach may determine the observed apparent half saturation constant, Km. Our experimental and model data both show that sulfate reduction in the studied marine sediment could be explained by two dominating affinities for sulfate: a low affinity with a mean half saturation constant, Km, of 430 μM SO 42- and a high affinity with a mean Km of 2.6 μM SO 42-. The high-affinity sulfate reduction was thermodynamically un-constrained down to <1 μM SO 42-, both in our experiments and under in situ conditions. The reduction of radio-labeled sulfate was partly reversible due to concurrent re-oxidation of sulfide by Fe(III) and possibly due to a reversibility of the enzymatic pathway of sulfate reduction. A literature survey of apparent Km values for sediments and pure cultures is presented and discussed.

  7. Microbiome Dynamics of a Polychlorobiphenyl (PCB) Historically Contaminated Marine Sediment under Conditions Promoting Reductive Dechlorination

    PubMed Central

    Matturro, Bruna; Ubaldi, Carla; Rossetti, Simona

    2016-01-01

    The toxicity of polychlorinated biphenyls (PCB) can be efficiently reduced in contaminated marine sediments through the reductive dechlorination (RD) process lead by anaerobic organohalide bacteria. Although the process has been extensively investigated on PCB-spiked sediments, the knowledge on the identity and metabolic potential of PCB-dechlorinating microorganisms in real contaminated matrix is still limited. Aim of this study was to explore the composition and the dynamics of the microbial communities of the marine sediment collected from one of the largest Sites of National Interest (SIN) in Italy (Mar Piccolo, Taranto) under conditions promoting the PCBs RD. A long-term microcosm study revealed that autochthonous bacteria were able to sustain the PCB dechlorination at a high extent and the successive addition of an external fermentable organic substrate (lactate) caused the further depletion of the high-chlorinated PCBs (up to 70%). Next Generation Sequencing was used to describe the core microbiome of the marine sediment and to follow the changes caused by the treatments. OTUs affiliated to sulfur-oxidizing ε-proteobacteria, Sulfurovum, and Sulfurimonas, were predominant in the original sediment and increased up to 60% of total OTUs after lactate addition. Other OTUs detected in the sediment were affiliated to sulfate reducing (δ-proteobacteria) and to organohalide respiring bacteria within Chloroflexi phylum mainly belonging to Dehalococcoidia class. Among others, Dehalococcoides mccartyi was enriched during the treatments even though the screening of the specific reductive dehalogenase genes revealed the occurrence of undescribed strains, which deserve further investigations. Overall, this study highlighted the potential of members of Dehalococcoidia class in reducing the contamination level of the marine sediment from Mar Piccolo with relevant implications on the selection of sustainable bioremediation strategies to clean-up the site. PMID:27708637

  8. Observations of gas hydrates in marine sediments, offshore northern California

    USGS Publications Warehouse

    Brooks, J.M.; Field, M.E.; Kennicutt, M.C.

    1991-01-01

    Biogenic gas hydrates were recovered in shallow cores (< 6 m deep) from the Eel River basin in offshore northern California between 40??38??? and 40??56???N. The gas hydrates contained primarily methane (??13C = -57.6 to -69.1???) and occurred as dispersed crystals, small (2-20 mm) nodules, and layered bands within the sediment. These hydrates, recovered in sediment at water depths between 510 and 642 m, coincide nearly, but not exactly, with areas showing bottom-simulating reflectors (BSRs) on seismic-reflection records. This study confirms indirect geophysical and geologic observations that gas hydrates are present north of the Mendocino Fracture Zone in sediment of the Eel River basin but probably are absent to the south in the Point Arena basin. This discovery extends the confirmed sites of gas hydrates in the eastern Pacific region beyond the Peruvian and Central American margins to the northern California margin. ?? 1991.

  9. Abiotic racemization kinetics of amino acids in marine sediments.

    PubMed

    Steen, Andrew D; Jørgensen, Bo Barker; Lomstein, Bente Aa

    2013-01-01

    The ratios of d- versus l-amino acids can be used to infer the sources and composition of sedimentary organic matter. Such inferences, however, rely on knowing the rates at which amino acids in sedimentary organic matter racemize abiotically between the d- and the l-forms. Based on a heating experiment, we report kinetic parameters for racemization of aspartic acid, glutamic acid, serine, and alanine in bulk sediment from Aarhus Bay, Denmark, taken from the surface, 30 cm, and 340 cm depth below seafloor. Extrapolation to a typical cold deep sea sediment temperature of 3°C suggests racemization rate constants of 0.50×10(-5)-11×10(-5) yr(-1). These results can be used in conjunction with measurements of sediment age to predict the ratio of d:l amino acids due solely to abiotic racemization of the source material, deviations from which can indicate the abundance and turnover of active microbial populations.

  10. Denitrification, Anammox, and N2 Production in Marine Sediments

    NASA Astrophysics Data System (ADS)

    Devol, Allan H.

    2015-01-01

    Fixed nitrogen limits primary productivity in many parts of the global ocean, and it consequently plays a role in controlling the carbon dioxide content of the atmosphere. The concentration of fixed nitrogen is determined by the balance between two processes: the fixation of nitrogen gas into organic forms by diazotrophs, and the reconversion of fixed nitrogen to nitrogen gas by denitrifying organisms. However, current sedimentary denitrification rates are poorly constrained, especially in permeable sediments, which cover the majority of the continental margin. Also, anammox has recently been shown to be an additional pathway for the loss of fixed nitrogen in sediments. This article briefly reviews sedimentary fixed nitrogen loss by sedimentary denitrification and anammox, including in sediments in contact with oxygen-deficient zones. A simple extrapolation of existing rate measurements to the global sedimentary denitrification rate yields a value smaller than many existing measurement-based estimates but still larger than the rate of water column denitrification.

  11. Relationship between acid volatile sulfide and the toxicity of zinc, lead and copper in marine sediments

    SciTech Connect

    Casas, A.M. . School of Fisheries); Crecelius, E.A. )

    1994-03-01

    It has been proposed that acid volatile sulfide (AVS) is an important sediment phase for determining the toxicity of certain trace metals. By evaluating the ratio of the molar quantities of simultaneously extracted metal (SEM) to AVS, the toxicity of metals to organisms in contact with sediment can be predicted. This study examines the role of AVS in prediction the toxicity of zinc, lead, and copper in marine sediments. Sediment samples were titrated with zinc, lead, and copper and subsequently analyzed for SEM, pore-water (PW) metal, and AVS retention. In most cases, metal was not detected in the pore waters until the AVS was exceeded, suggesting that AVS is an adequate measure of the metal-blinding capacity of a sediment. The [SEM]-to-[AVS] ratios were calculated and toxicities predicted for each spiking concentration where [SEM]/[AVS] > 1. A 10-d, flow-though, acute bioassay using the marine polychaete Capitella capita was conducted to examine the prediction of toxicity from the metal titrations and the bioassay sediment chemistry data. In most cases, mortalities occurred as predicted. AVS and the [SEM]-to-[AVS] ratio proved useful as predictors of toxicity for zinc, lead, and perhaps copper. Another tool for predicting metal toxicity in sediments may be the [PW]/LC50 value; in every case where this ratio was > 1, mortalities occurred.

  12. Accumulation of polychlorinated organic contaminants from sediment by three benthic marine species

    SciTech Connect

    Pruell, R.J.; Rubinstein, N.I.; Taplin, B.K.; LiVolsi, J.A.; Bowen, R.D.

    1993-01-01

    A laboratory experiment was conducted to measure the accumulation of selected polychlorinated compounds by marine benthos exposed to environmentally contaminated sediment. Sandworms (Nereis virens), clams (Macoma nasuta), and grass shrimp (Palaemonetes pugio) were exposed to sediment collected from the Passaic River, New Jersey. All three species accumulated 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), 2,3,7,8-tetrachlorodibenzofuran (2,3,7,8-TCDF) and polychlorinated biphenyls (PCBs) from the sediment. In addition, a recently identified sulfur containing analog of tetrachlorinated dibenzofurans. The objectives of the study were to determine the relative bioavailability of 2,3,7,8-TCDD, 2,3,7,8-tetrachlorodibenzofuran (2,3,7,8-TCDF) and selected PCB congeners from bottom sediments as well as to examine the relationship between contaminant concentrations in sediments and biota.

  13. Cathodic protection by zinc sacrificial anodes: impact on marine sediment metallic contamination.

    PubMed

    Rousseau, C; Baraud, F; Leleyter, L; Gil, O

    2009-08-15

    Cathodic protection by sacrificial zinc anodes is often applied to prevent immerged metallic structures from corrosion. But this technique induces the zinc anodes dissolution, which can induce marine sediments and seawater contamination. A large scale experiment, in natural seawater, was conducted during 12 months, in order to evaluate the potential environmental impact of this continuous zinc dissolution, and of some necessary cleaning operations of the anodes surfaces. The heavy metal (Cr, Cu, Pb and Zn) concentration in water and sediment samples was monitored. A sequential extraction procedure was applied on sediment samples to differentiate the zinc mobile fractions from the residual one. A significant increase of zinc concentration was observed in water as well as in the surface sediments under the specific operating conditions. Sediments then become a secondary pollution source, as the sorbed labile zinc can be remobilized to seawater. PMID:19250740

  14. Sorption behaviors of a persistent toxaphene congener on marine sediments under different physicochemical conditions.

    PubMed

    Soubaneh, Youssouf Djibril; Gagné, Jean-Pierre; Lebeuf, Michel; Gouteux, Bruno; Nikiforov, Vladimir; Awaleh, Mohamed Osman

    2014-11-01

    Sorptive processes are important parameters affecting the mobility, availability and fate of persistent organic pollutants (POPs), such as toxaphene, in aquatic systems. The sorption and desorption behaviors of the B7-1450, a stable toxaphene congener in environment, on marine sediment was studied under different temperature and salinity conditions to better understand the B-1450 distribution in estuarine systems. The data were fitted to different sorption models to characterize sorption behaviors by evaluating sorption coefficients and sequestrated fraction of B7-1450 on sediments. High carbon-normalized sorption coefficients (Koc) of the B7-1450 were observed with values ranging from 3.2×104 to 6.0×104 mL g(-1) under experimental conditions. The data showed an increase of B7-1450 sorption coefficients with the salinity and a decrease with temperature. These investigations indicate that B7-1450 is three times more sequestred on sediments in cold (2°C, 30 psu) than in warm marine conditions (20°C, 30 psu). These results suggest that the mobility and bioavailable of B7-1450 or other POPs from the sediments could be less important in cold marine comparatively in warm marine and warm freshwater media. As a result of climate changes, the warming of mid and high latitudes coastal waters could enhance the mobility of POPs.

  15. APPLICATION OF COMPUTER-AIDED TOMOGRAPHY TO VISUALIZE AND QUANTIFY BIOGENIC STRUCTURES IN MARINE SEDIMENTS

    EPA Science Inventory

    We used computer-aided tomography (CT) for 3D visualization and 2D analysis of

    marine sediment cores from 3 stations (at 10, 75 and 118 m depths) with different environmental

    impact. Biogenic structures such as tubes and burrows were quantified and compared among st...

  16. Molybdenum Accumulation in Marine Sediments as an Indicator of Hypoxic Water Conditions (NACAETAC)

    EPA Science Inventory

    Direct monitoring of hypoxic water column conditions over large spatial and temporal extents is difficult due to the substantial logistical and financial investment required. Recent studies have indicated that concentrations of molybdenum (Mo) in marine sediments may serve as a u...

  17. Sorption behaviors of a persistent toxaphene congener on marine sediments under different physicochemical conditions.

    PubMed

    Soubaneh, Youssouf Djibril; Gagné, Jean-Pierre; Lebeuf, Michel; Gouteux, Bruno; Nikiforov, Vladimir; Awaleh, Mohamed Osman

    2014-11-01

    Sorptive processes are important parameters affecting the mobility, availability and fate of persistent organic pollutants (POPs), such as toxaphene, in aquatic systems. The sorption and desorption behaviors of the B7-1450, a stable toxaphene congener in environment, on marine sediment was studied under different temperature and salinity conditions to better understand the B-1450 distribution in estuarine systems. The data were fitted to different sorption models to characterize sorption behaviors by evaluating sorption coefficients and sequestrated fraction of B7-1450 on sediments. High carbon-normalized sorption coefficients (Koc) of the B7-1450 were observed with values ranging from 3.2×104 to 6.0×104 mL g(-1) under experimental conditions. The data showed an increase of B7-1450 sorption coefficients with the salinity and a decrease with temperature. These investigations indicate that B7-1450 is three times more sequestred on sediments in cold (2°C, 30 psu) than in warm marine conditions (20°C, 30 psu). These results suggest that the mobility and bioavailable of B7-1450 or other POPs from the sediments could be less important in cold marine comparatively in warm marine and warm freshwater media. As a result of climate changes, the warming of mid and high latitudes coastal waters could enhance the mobility of POPs. PMID:25113217

  18. Diversity of Thiosulfate-Oxidizing Bacteria from Marine Sediments and Hydrothermal Vents†

    PubMed Central

    Teske, A.; Brinkhoff, T.; Muyzer, G.; Moser, D. P.; Rethmeier, J.; Jannasch, H. W.

    2000-01-01

    Species diversity, phylogenetic affiliations, and environmental occurrence patterns of thiosulfate-oxidizing marine bacteria were investigated by using new isolates from serially diluted continental slope and deep-sea abyssal plain sediments collected off the coast of New England and strains cultured previously from Galapagos hydrothermal vent samples. The most frequently obtained new isolates, mostly from 103- and 104-fold dilutions of the continental slope sediment, oxidized thiosulfate to sulfate and fell into a distinct phylogenetic cluster of marine alpha-Proteobacteria. Phylogenetically and physiologically, these sediment strains resembled the sulfate-producing thiosulfate oxidizers from the Galapagos hydrothermal vents while showing habitat-related differences in growth temperature, rate and extent of thiosulfate utilization, and carbon substrate patterns. The abyssal deep-sea sediments yielded predominantly base-producing thiosulfate-oxidizing isolates related to Antarctic marine Psychroflexus species and other cold-water marine strains of the Cytophaga-Flavobacterium-Bacteroides phylum, in addition to gamma-proteobacterial isolates of the genera Pseudoalteromonas and Halomonas-Deleya. Bacterial thiosulfate oxidation is found in a wide phylogenetic spectrum of Flavobacteria and Proteobacteria. PMID:10919760

  19. Estimating production and consumption of solid reactive Fe phases in marine sediments from concentration profiles

    EPA Science Inventory

    1D diffusion models may be used to estimate rates of production and consumption of dissolved metabolites in marine sediments, but are applied less often to the solid phase. Here we used a numerical inverse method to estimate solid phase Fe(III) and Fe(II) consumption and product...

  20. Comparative phosphorus sorption by marine sediments and agricultural soils in a tropical environment.

    PubMed

    Fox, Robert L; Fares, Ali; Wan, Y; Evensen, Carl I

    2006-01-01

    The influence of soil phosphorus (P) sources on P sorption characteristics of marine sediments was investigated for Pearl Harbor and off shore Molokai in Hawaii. Estuary sediments were sampled in seven locations; these represented different soils and on-shore activities. The soil samples included nine major soils that contributed sediment to the Harbor and coastal sediments near the island of Molokai. Sediment and soil samples were equilibrated for 6 days in 0.01 M CaCl(2) solution and synthetic seawater containing differing amounts of P. Phosphorus sorption curves were constructed. The equilibrated solution P, with no P added, ranged from 0.01 to 0.2 mg L(-1); P sorption by sediments at standard solution concentration 0.2 mg L(-1), ranged from 0 to 230 mg kg(-1). Sediment P sorption corresponded closely with soil sorption characteristics. Soils contributing sediments to the west reach of Pearl Harbor are highly weathered Oxisols with high standard P sorption values while those in the southeast of the Harbor were Vertisols and Mollisols which sorb little P. The influence of source materials on sediment P sorption was also observed for off-shore sediments near Molokai. Sediments serve as both source and sink for P in Pearl Harbor and in this role can be a stabilizing influence on P concentration in the water column. Phosphorus sorption curves in conjunction with water quality data can help to understand P dynamics between sediments and the water column and help evaluate concerns about P loading to a water body. For Pearl Harbor, solution P in equilibrium with sediments from the Lochs was 0.021 mg L(-1); a value unlikely to produce an algal bloom. (Measured total P in the water columns (mean) was 0.060.).

  1. Marine protist diversity in European coastal waters and sediments as revealed by high-throughput sequencing.

    PubMed

    Massana, Ramon; Gobet, Angélique; Audic, Stéphane; Bass, David; Bittner, Lucie; Boutte, Christophe; Chambouvet, Aurélie; Christen, Richard; Claverie, Jean-Michel; Decelle, Johan; Dolan, John R; Dunthorn, Micah; Edvardsen, Bente; Forn, Irene; Forster, Dominik; Guillou, Laure; Jaillon, Olivier; Kooistra, Wiebe H C F; Logares, Ramiro; Mahé, Frédéric; Not, Fabrice; Ogata, Hiroyuki; Pawlowski, Jan; Pernice, Massimo C; Probert, Ian; Romac, Sarah; Richards, Thomas; Santini, Sébastien; Shalchian-Tabrizi, Kamran; Siano, Raffaele; Simon, Nathalie; Stoeck, Thorsten; Vaulot, Daniel; Zingone, Adriana; de Vargas, Colomban

    2015-10-01

    Although protists are critical components of marine ecosystems, they are still poorly characterized. Here we analysed the taxonomic diversity of planktonic and benthic protist communities collected in six distant European coastal sites. Environmental deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) from three size fractions (pico-, nano- and micro/mesoplankton), as well as from dissolved DNA and surface sediments were used as templates for tag pyrosequencing of the V4 region of the 18S ribosomal DNA. Beta-diversity analyses split the protist community structure into three main clusters: picoplankton-nanoplankton-dissolved DNA, micro/mesoplankton and sediments. Within each cluster, protist communities from the same site and time clustered together, while communities from the same site but different seasons were unrelated. Both DNA and RNA-based surveys provided similar relative abundances for most class-level taxonomic groups. Yet, particular groups were overrepresented in one of the two templates, such as marine alveolates (MALV)-I and MALV-II that were much more abundant in DNA surveys. Overall, the groups displaying the highest relative contribution were Dinophyceae, Diatomea, Ciliophora and Acantharia. Also, well represented were Mamiellophyceae, Cryptomonadales, marine alveolates and marine stramenopiles in the picoplankton, and Monadofilosa and basal Fungi in sediments. Our extensive and systematic sequencing of geographically separated sites provides the most comprehensive molecular description of coastal marine protist diversity to date.

  2. The Atmospheric Supply of Terrestrial Authigenic Phosphate Minerals to Open Marine Sediments

    NASA Astrophysics Data System (ADS)

    Flaum, J. A.; Jacobson, A. D.; Sageman, B. B.

    2007-12-01

    Authigenic P-bearing minerals (Pauth), such as carbonate fluorapatite, form within shallow marine sediments as biological processes degrade organic matter and release associated phosphate to the dissolved pool during early diagenesis. Thus, Pauth is commonly used as a proxy for productivity in modern and ancient marine depositional environments. To help refine this proxy and further improve understanding of the marine P cycle, we investigated if dust deposition could supply terrestrially derived Pauth and other P-bearing phases to modern marine sediments. We used the SEDEX sequential extraction procedure to quantify the occurrence of P in ten samples of loess from the Chinese Loess Plateau, a major source of dust to the North Pacific Ocean (NPO). On average, 40% of the total P within Chinese Loess occurs as Pauth, 33% as detrital apatite (Pdet), 17% in organic matter (Porg), and 10% bound to Fe-Al oxides (Pox). Using eolian dust and total P accumulation rates reported for core LL44-GC3 taken from the central NPO, we find that ~86% of the total P accumulation within the central NPO could originate from the atmospheric deposition of Pauth and Pdet. Hence, productivity estimates based upon total P accumulation for this site are likely lower than previously estimated. Our findings suggest that marine productivity studies predicated on the measurement of Pauth need to quantify the fraction of Pauth supplied from terrestrial sources. This may be even more significant along continental margins where rivers can supply sediments with high concentrations of Pauth minerals.

  3. HCH and DDT in sediments from marine and adjacent riverine areas of North Bohai Sea, China.

    PubMed

    Hu, Wenyou; Wang, Tieyu; Khim, Jong Seong; Luo, Wei; Jiao, Wentao; Lu, Yonglong; Naile, Jonathan E; Chen, Chunli; Zhang, Xiang; Giesy, John P

    2010-07-01

    Residues of organochlorine pesticides (OCPs), hexachlorocyclohexanes (HCHs), and dichlorodiphenyltrichloroethanes (DDTs) and their environmental risks in surface sediments collected from marine and adjacent riverine/estuarine areas in the northern Bohai Sea, China, were investigated. Concentrations of SigmaHCH and SigmaDDT in sediments ranged from below detection (marine than riverine sediments. Concentrations of HCH and DDT residues found in the present study were higher than those reported in marine and river/estuary sediments from other areas of the world. The source of HCH in sediments could be explained by the large amount of historical use, while DDT seemed to be a combination of erosion of the weathered soils and long-range atmospheric transport. Concentrations of HCH in sediments from the study areas did not exceed sediment quality guidelines (SQGs), with the exception of gamma-HCH. However, risks posed by concentrations of DDT observed in sediments were found to be moderate to high compared with those posed by consensus-based SQGs. Although the mean sedimentary concentrations of HCH and DDT found in the area of the northern Bohai Sea, China were lower than suggested SQGs in general, their concentrations in some locations were close to or above the SQGs for adverse effects in benthic organisms and, thus, remain a cause for concern.

  4. Development and Evaluation of Polychaete Reverse Samplers for Marine Phase II Whole Sediment Toxicitiy Identification Evaluations (TIE)

    EPA Science Inventory

    Marine and estuarine sediments accumulate contaminants and act as a sink for a wide range of toxic chemicals. As a result, the sediments themselves can become a source of contamination. At sufficient levels, contaminated sediments can cause benthic impairments and toxicity to m...

  5. Development and Evaluation of Reverse Polyethylene Samplers for Marine Phase II Whole-Sediment Toxicity Identification Evaluation

    EPA Science Inventory

    Marine and estuarine sediments accumulate contaminants and act as a sink for a wide range of toxic chemicals. As a result, the sediments themselves can become a source of contamination. At sufficient levels, contaminated sediments can cause benthic impairments and toxicity to mar...

  6. Neutron activation analysis of major, minor, and trace elements in marine sediments

    SciTech Connect

    Stone, S.F.; Zeisler, R.; Koster, B.J.

    1988-01-01

    Neutron activation analysis (NAA) techniques are well established in the multielement assay of geological materials. Similarly, applications of NAA to the analysis of marine sediments have been described. The different emphasis on elemental composition in studying and monitoring the health of the environment, however, presents a new challenge to the analyst. To investigate as many elements as possible, previous multielement procedures need to be reevaluated and modified. In this work, the authors have utilized the NAA steps of a recently developed sequential analysis procedure that obtained concentrations for 45 biological and pollutant elements in marine bivalves. This procedure, with modification, was applied to samples of marine sediments collected for the National Oceanic and Atmospheric Administration (NOAA) National Status and Trends (NS T) specimen banking program.

  7. Optimization of hard clams, polychaetes, physical disturbance and denitrifying bacteria of removing nutrients in marine sediment.

    PubMed

    Shen, Hui; Thrush, Simon F; Wan, Xihe; Li, Hui; Qiao, Yi; Jiang, Ge; Sun, Ruijian; Wang, LiBao; He, Peimin

    2016-09-15

    Marine organisms are known to play important roles in transforming nutrients in sediments, however, guidelines to optimize sediment restoration are not available. We conducted a laboratory mesocosm experiment to investigate the role of hard clams, polychaetes, the degree of physical disturbance and denitrifying bacterial concentrations in removing total nitrogen (TN), total phosphorus (TP), and total organic carbon (TOC) in marine sediments. Response surface methodology was employed to analyze the results of initial experiments and in a subsequent experiment identified optimal combinations of parameters. Balancing the TN, TP, TOC removal efficiency, our model predicted 39% TN removal, 33% TP removal, and 42% TOC removal for a 14-day laboratory bioremediation trial using hard clams biomass of 1.2kgm(-2), physical disturbance depth of 16.4cm, bacterial density of 0.18Lm(-2), and polychaetes biomass of 0.16kgm(-2), respectively. These results emphasize the value of combining different species in field-based bioremediation.

  8. Optimization of hard clams, polychaetes, physical disturbance and denitrifying bacteria of removing nutrients in marine sediment.

    PubMed

    Shen, Hui; Thrush, Simon F; Wan, Xihe; Li, Hui; Qiao, Yi; Jiang, Ge; Sun, Ruijian; Wang, LiBao; He, Peimin

    2016-09-15

    Marine organisms are known to play important roles in transforming nutrients in sediments, however, guidelines to optimize sediment restoration are not available. We conducted a laboratory mesocosm experiment to investigate the role of hard clams, polychaetes, the degree of physical disturbance and denitrifying bacterial concentrations in removing total nitrogen (TN), total phosphorus (TP), and total organic carbon (TOC) in marine sediments. Response surface methodology was employed to analyze the results of initial experiments and in a subsequent experiment identified optimal combinations of parameters. Balancing the TN, TP, TOC removal efficiency, our model predicted 39% TN removal, 33% TP removal, and 42% TOC removal for a 14-day laboratory bioremediation trial using hard clams biomass of 1.2kgm(-2), physical disturbance depth of 16.4cm, bacterial density of 0.18Lm(-2), and polychaetes biomass of 0.16kgm(-2), respectively. These results emphasize the value of combining different species in field-based bioremediation. PMID:27371956

  9. Recent sediment remolding on a deep shelf, Ross Sea: implications for radiocarbon dating of Antarctic marine sediments

    NASA Astrophysics Data System (ADS)

    Domack, Eugene W.; Taviani, Marco; Rodriguez, Anthonio

    1999-11-01

    Coarse, bioclastic rich sands have been widely reported from the banks of the Antarctic continental shelf but their origin is still poorly known. We report on a suite of coarse sediments recovered from the top of the Mawson Bank in the northwestern Ross Sea. Radiocarbon ages of biogenic calcite, for modern and apparently late Pleistocene deposits, range from 1085±45 to 20,895±250 yr B.P.. Discovery of soft tissue (Ascidian) preserved as an incrustation on a pebble at 2 m depth indicates aggregation of the sediment within several months or a year of core recovery. Radiocarbon ages of acid insoluble organic matter (aiom) are less than those of the foraminifera calcite. The aiom ages are also reversed in sequence, indicating reworking of the sediment during deposition. These observations and a review of recently published literature suggest that much of the bank top sediment in Antarctica is presently undergoing remobilization, under the influence of strong currents and/or icebergs even under interglacical (high-stand) sea levels. These observations point out the need for careful, integrated studies on high latitude marine sediment cores before resultant "ages" alone are used as the foundation for paleoglacial reconstructions.

  10. Enhancement of dimethylsulfide production by anoxic stress in natural seawater

    NASA Astrophysics Data System (ADS)

    Omori, Yuko; Tanimoto, Hiroshi; Inomata, Satoshi; Wada, Shigeki; Thume, Kathleen; Pohnert, Georg

    2015-05-01

    Dimethylsulfide (DMS) is produced by phytoplankton in the ocean and plays an important role in biogeochemical cycles and climate system of the Earth. Previous field studies reported a possible relationship between DMS enhancement and anoxic condition, although the governing processes are still to be identified. Here we show the first direct evidence for the enhancement of DMS production by natural planktonic assemblages caused by anoxic stress. Under the anoxic condition, DMS production was considerably enhanced and DMS bacterial consumption was inhibited, resulting in an eightfold higher rate of gross DMS production than that under the oxic condition. Our results demonstrated that anoxic stress is one of important "environmental factors" in the marine DMS dynamics, suggesting the possible global importance due to ubiquity of anoxic conditions in the coastal oceans. This process would become more important in the future due to expansion of coastal hypoxic and anoxic zones by global warming.

  11. 20th-century glacial-marine sedimentation in Vitus Lake, Bering Glacier, Alaska, U.S.A.

    USGS Publications Warehouse

    Molnia, B.F.; Post, A.; Carlson, P.R.

    1996-01-01

    Vitus Lake, the ice-marginal basin at the southeastern edge of Bering Glacier, Alaska, U.S.A., is a site of modern, rapid, glacial-marine sedimentation. Rather than being a fresh-water lake, Vitus Lake is a tidally influenced, marine to brackish embayment connected to the Pacific Ocean by an inlet, the Seal River. Vitus Lake consists of five deep bedrock basins, separated by interbasinal highs. Glacial erosion has cut these basins as much as 250 m below sea level. High-resolution seismic reflection surveys conducted in 1991 and 1993 of four of Vitus Lake's basins reveal a complex, variable three-component acoustic stratigraphy. Although not fully sampled, the stratigraphy is inferred to be primarily glacial-marine units of (1) basal contorted and deformed glacial-marine and glacial sediments deposited by basal ice-contact processes and submarine mass-wasting; (2) acoustically well-stratified glacial-marine sediment, which unconformably overlies the basal unit and which grades upward into (3) acoustically transparent or nearly transparent glacial-marine sediment. Maximum thicknesses of conformable glacial-marine sediment exceed 100 m. All of the acoustically transparent and stratified deposits in Vitus Lake are modern in age, having accumulated between 1967 and 1993. The basins where these three-part sequences of "present-day" glacial-marine sediment are accumulating are themselves cut into older sequences of stratified glacial and glacial-marine deposits. These older units outcrop on the islands in Vitus Lake. In 1967, as the result of a major surge, glacier ice completely filled all five basins. Subsequent terminus retreat, which continued through August 1993, exposed these basins, providing new locations for glacial-marine sediment accumulation. A correlation of sediment thicknesses measured from seismic profiles at specific locations within the basins, with the year that each location became ice-free, shows that the sediment accumulation at some locations

  12. Prevailing oxic environments in the Pacific Ocean during the mid-Cretaceous Oceanic anoxic event 2.

    PubMed

    Takashima, Reishi; Nishi, Hiroshi; Yamanaka, Toshiro; Tomosugi, Takashige; Fernando, Allan G; Tanabe, Kazushige; Moriya, Kazuyoshi; Kawabe, Fumihisa; Hayashi, Keiichi

    2011-01-01

    The occurrence of Oceanic Anoxic Event 2 (OAE2) 94 million years ago is considered to be one of the largest carbon cycle perturbations in the Earth's history. The marked increase in the spatial extent of the anoxic conditions in the world's oceans associated with OAE2 resulted in the mass accumulation of organic-rich sediments. Although extensive oceanographic studies of OAE2 have been undertaken in the Atlantic Ocean, the Tethys Sea, and the epicontinental seas of Europe and America, little is known about OAE2 in the Pacific Ocean. Here, we present high-resolution carbon-isotope and degree of pyritization (DOP) data from marine sequences that formed along the continental margins of North America and Asia below the northeastern and northwestern Pacific Ocean. The predominance of low DOP values in these areas revealed that the continental margins of the Pacific Ocean were oxic for most of the OAE2 interval.

  13. Sequential Sediment Budgets in an Ungauged Watershed: Redwood Creek, Marin County, California

    NASA Astrophysics Data System (ADS)

    Downs, P. W.; Stallman, J.

    2005-12-01

    Sediment budgets provide an organizing framework in fluvial geomorphology and have enormous potential in environmental management. A sediment budget approach assisted in developing strategies for restoring Big Lagoon, the wetland ecosystem at the terminus of the 22.7 km2 Redwood Creek watershed in Marin County, California. Persistence of a restored lagoon largely depends on the current sediment yield relative to the reference yield prior to European settlement. Process-based, distributed sediment budgets were constructed for several historical time periods to account for accelerated sediment production from contemporary land management practices and legacy factors stemming from past resource exploitation. Sediment production, storage, and transfer were investigated using digital terrain modeling, field reconnaissance to ascertain and validate hillslope processes, mainstem channel surveys and dendrochronology to assess trends in alluvial sediment storage, application of published process rate estimates, use of short-term and prorated stream gauging records, and sediment transport modeling to validate sediment yields into Big Lagoon. Evidence suggests that the Redwood Creek valley bottom aggraded from at least 3,500 B.P., with floodplain wetlands acting as sediment sinks (average annual sediment yield of 34 t km2 yr-1). Channel incision rapidly followed European settlement and intensive hillslope disturbances beginning around 1840 (peak yield 1921-1982 of 324 t km2 yr-1). Mainstem and large tributary valley bottoms became major sediment sources during this time and remain sources despite progressive retirement of most agricultural land use (yield 1981-2000 of 198 t km2 yr-1). Numerous issues related to data availability and resolution limited quantification of some sediment sources and resulted in potential uncertainties in estimates of yield to Big Lagoon. Historical sediment budgets, however, require more than adequate data sources, they require accurate conceptual

  14. Food quality determines sediment community responses to marine vs. terrigenous organic matter in a submarine canyon

    NASA Astrophysics Data System (ADS)

    Hunter, W. R.; Jamieson, A.; Huvenne, V. A. I.; Witte, U.

    2012-08-01

    The Whittard canyon is a branching submarine canyon on the Celtic continental margin, which may act as a conduit for sediment and organic matter (OM) transport from the European continental slope to the abyssal sea floor. In situ stable-isotope labelling experiments were conducted in the eastern and western branches of the Whittard canyon testing short term (3-7 day) responses of sediment communities to deposition of nitrogen-rich marine (Thallassiosira weissflogii) and nitrogen-poor terrigenous (Triticum aestivum) phytodetritus. 13C and 15N labels were traced into faunal biomass and bulk sediments, and the 13C label traced into bacterial polar lipid fatty acids (PLFAs). Isotopic labels penetrated to 5 cm sediment depth, with no differences between stations or experimental treatments (substrate or time). Macrofaunal assemblage structure differed between the eastern and western canyon branches. Following deposition of marine phytodetritus, no changes in macrofaunal feeding activity were observed between the eastern and western branches, with little change between 3 and 7 days. Macrofaunal C and N uptake was substantially lower following deposition of terrigenous phytodetritus with feeding activity governed by a strong N demand. Bacterial C uptake was greatest, in the western branch of the Whittard canyon, but feeding activity decreased between 3 and 7 days. Bacterial processing of marine and terrigenous OM were similar to the macrofauna in surficial (0-1 cm) sediments. However, in deeper sediments bacteria utilised greater proportions of terrigenous OM. Bacterial biomass decreased following phytodetritus deposition and was negatively correlated to macrofaunal feeding activity. Consequently, this study suggests that macrofaunal-bacterial interactions influence benthic C cycling in the Whittard canyon, resulting in differential fates for marine and terrigenous OM.

  15. Distributions and biomass of benthic ciliates, foraminifera and amoeboid protists in marine, brackish, and freshwater sediments.

    PubMed

    Lei, Yan-Li; Stumm, Karen; Wickham, Stephen A; Berninger, Ulrike-G

    2014-01-01

    The quantitative importance of ciliates, foraminifers, and amoebae was investigated in marine, brackish, and freshwater sediments from 15 littoral stations. Total protozoan communities were usually dominated by ciliates in term of abundance, while amoebae often dominated in terms of biomass. Applying the biomass-metabolic rate equation, ciliates, amoebae, and foraminifera were estimated to contribute 66% of the total abundance and 33% of the biomass, but up to 55% of the combined metabolic rate to the micro- and meiobenthos in the 15 sediments. Statistical analyses using ciliate data demonstrated: (1) species composition and community structures represented significant differences between freshwater and marine/brackish sediments, and subsequently between temperate and arctic sampling sites; (2) the occurrence of dominant ciliates and their allocation to feeding types indicated that herbivory was the most common feeding strategy in these sediments; (3) multivariate analyses showed all of the tested environmental factors (temperature, salinity, silt/clay, carbon, nitrogen, and chlorophyll a) to be important to varying degrees, but especially the combination of salinity, temperature, and silt/clay. Multiple factor effects or comprehensive influences might be important in regulating the distribution of protozoa in sediments. The importance of protozoa in sediment systems and the potential ecological significance of cysts are discussed. PMID:24919761

  16. Distributions and biomass of benthic ciliates, foraminifera and amoeboid protists in marine, brackish, and freshwater sediments.

    PubMed

    Lei, Yan-Li; Stumm, Karen; Wickham, Stephen A; Berninger, Ulrike-G

    2014-01-01

    The quantitative importance of ciliates, foraminifers, and amoebae was investigated in marine, brackish, and freshwater sediments from 15 littoral stations. Total protozoan communities were usually dominated by ciliates in term of abundance, while amoebae often dominated in terms of biomass. Applying the biomass-metabolic rate equation, ciliates, amoebae, and foraminifera were estimated to contribute 66% of the total abundance and 33% of the biomass, but up to 55% of the combined metabolic rate to the micro- and meiobenthos in the 15 sediments. Statistical analyses using ciliate data demonstrated: (1) species composition and community structures represented significant differences between freshwater and marine/brackish sediments, and subsequently between temperate and arctic sampling sites; (2) the occurrence of dominant ciliates and their allocation to feeding types indicated that herbivory was the most common feeding strategy in these sediments; (3) multivariate analyses showed all of the tested environmental factors (temperature, salinity, silt/clay, carbon, nitrogen, and chlorophyll a) to be important to varying degrees, but especially the combination of salinity, temperature, and silt/clay. Multiple factor effects or comprehensive influences might be important in regulating the distribution of protozoa in sediments. The importance of protozoa in sediment systems and the potential ecological significance of cysts are discussed.

  17. Luminescence Dating of Marine Terrace Sediments Between Trabzon and Rize, Eastern Black Sea Basin: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Softa, Mustafa; Spencer, Joel Q. G.; Emre, Tahir; Sözbilir, Hasan; Turan, Mehmet

    2016-04-01

    Quaternary marine terraces in the coastal region of Pontides in Northeastern Turkey are valuable archives of past sea level change. Until recently, dates of raised marine terraces undeciphered in the coastal region between Trabzon and Rize because of chronologic limitations. In this paper was to determine ages of the terrace deposits by applying optically stimulated luminescence (OSL) dating methods using single aliquot regenerative dose (SAR) techniques on quartz minerals from extracted marine terraces. Several samples were collected from three orders of Quaternary marine terraces which are reproducible at all sampling location in between cities of Trabzon and Rize, Turkey, coastal of Eastern Pontides, at the front of the thrust system. The terrace deposits mainly consist of clays, silts, sands and gravels. The sediments in these deposits are mainly derived from basaltic, andesitic, and limestone geology, and have elipsoid, square and flat shapes. The terrace deposits have heights ranging from 1 to 17 meters and increases in height and thickness from west to east. Initial OSL results from 1 mm and 3 mm quartz aliquots demonstrate good luminescence characteristics. Preliminary equivalent dose analysis results ranging from 17.6 Gy to 79.6 Gy have been calculated using the Central Age Model (CAM) and Minimum Age Model (MAM). According to ages obtained from three separate terrace is ~8 ka, ~42 ka and ~78 ka, respectively. Results of marine terrace sediments indicate this region has three sedimentation periods and coastal region of Pontides has been remarkably tectonically active since latest Pleistocene to earlier Holocene. This study will present preliminary OSL dating results obtained from samples of Quaternary marine terrace formation. Keywords: optically stimulated luminescence (OSL) dating, single grain, marine terraces, Eastern Pontides.

  18. Estimates of Biogenic Methane Production Rates in Deep Marine Sediments at Hydrate Ridge, Cascadia Margin

    SciTech Connect

    F. S. Colwell; S. Boyd; M. E. Delwiche; D. W. Reed; T. J. Phelps; D. T. Newby

    2008-06-01

    Methane hydrate found in marine sediments is thought to contain gigaton quantities of methane and is considered an important potential fuel source and climate-forcing agent. Much of the methane in hydrates is biogenic, so models that predict the presence and distribution of hydrates require accurate rates of in situ methanogenesis. We estimated the in situ methanogenesis rates in Hydrate Ridge (HR) sediments by coupling experimentally derived minimal rates of methanogenesis to methanogen biomass determinations for discrete locations in the sediment column. When starved in a biomass recycle reactor Methanoculleus submarinus produced ca. 0.017 fmol methane/cell/day. Quantitative polymerase chain reaction (QPCR) directed at the methyl coenzyme M reductase subunit A (mcrA) gene indicated that 75% of the HR sediments analyzed contained <1000 methanogens/g. The highest methanogen numbers were mostly from sediments <10 meters below seafloor. By combining methanogenesis rates for starved methanogens (adjusted to account for in situ temperatures) and the numbers of methanogens at selected depths we derived an upper estimate of <4.25 fmol methane produced/g sediment/day for the samples with fewer methanogens than the QPCR method could detect. The actual rates could vary depending on the real number of methanogens and various seafloor parameters that influence microbial activity. However, our calculated rate is lower than rates previously reported from such sediments and close to the rate derived using geochemical modeling of the sediments. These data will help to improve models that predict microbial gas generation in marine sediments and determine the potential influence of this source of methane on the global carbon cycle.

  19. Marine sediment toxicity identification evaluation methods for the anionic metals arsenic and chromium.

    PubMed

    Burgess, Robert M; Perron, Monique M; Cantwell, Mark G; Ho, Kay T; Pelletier, Marguerite C; Serbst, Jonathan R; Ryba, Stephan A

    2007-01-01

    Marine sediments accumulate a variety of contaminants and, in some cases, demonstrate toxicity because of this contamination. Toxicity identification evaluation (TIE) methods provide tools for identifying the toxic chemicals causing sediment toxicity. Currently, whole-sediment TIE methods are not available for anionic metals like arsenic and chromium. In the present paper, we describe two new anion-exchange resins used in the development of whole-sediment TIE methods for arsenic and chromium. Resins were shown to reduce whole-sediment toxicity and overlying water concentrations of the anionic metals. Sediment toxicity, expressed as the median lethal concentration, was reduced by a factor of two to a factor of nearly six between amended sediment treatments containing resin and those without resin. Aqueous concentrations of arsenic and chromium in the toxicity exposures decreased to less than the detection limits or to concentrations much lower than those measured in treatments without resin. Interference studies indicated that the anion-exchange resins had no significant effect on concentrations of the representative pesticide endosulfan and minimal effects on concentrations of ammonia. However, the anion-exchange resins did significantly reduce the concentrations of a selection of cationic metals (Cd, Cu, Ni, Pb, and Zn). These data demonstrate the utility of anion-exchange resins for determining the contribution of arsenic and chromium to whole-sediment toxicity. The present results also indicate the importance of using TIE methods in a formal TIE structure to ensure that results are not misinterpreted. These methods should be useful in the performance of marine whole-sediment TIEs.

  20. Effects of organic matter addition on methylmercury formation in capped and uncapped marine sediments.

    PubMed

    Ndungu, Kuria; Schaanning, Morten; Braaten, Hans Fredrik Veiteberg

    2016-10-15

    In situ subaqueous capping (ISC) of contaminated marine sediments is frequently proposed as a feasible and effective mitigation option. However, though effective in isolating mercury species migration into overlying water, capping can also alter the location and extent of biogeochemical zones and potentially enhance methylmercury (MeHg) formation in Hg-contaminated marine sediments. We carried out a boxcosm study to investigate whether the addition of organic carbon (OC) to Hg-contaminated marine sediments beneath an in situ cap would initiate and/or enhance MeHg formation of the inorganic Hg present. The study was motivated by ongoing efforts to remediate ca. 30,000 m(2) of Hg-contaminated seabed sediments from a Hg spill from the U864 WWII submarine wreck. By the time of sinking, the submarine is assumed to have been holding a cargo of ca. 65 tons of liquid Hg. Natural organic matter and petroleum hydrocarbons from fuels and lubricants in the wreck are potential sources of organic carbon that could potentially fuel MeHg formation beneath a future cap. The results of our study clearly demonstrated that introduction of algae OC to Hg-contaminated sediments, triggered high rates of MeHg production as long a there was sufficient OC. Thus, MeHg production was limited by the amount of organic carbon available. The study results also confirmed that, within the six-month duration of the study and in the absence of bioturbating fauna, a 3-cm sediment clay cap could effectively reduce fluxes of Hg species to the overlying water and isolate the Hg-contaminated sediments from direct surficial deposition of organic matter that could potentially fuel methylation. PMID:27494695

  1. Acetate and other Volatile Fatty Acids - Key Intermediates in marine sediment metabolism - Thermodynamic and kinetic implications

    NASA Astrophysics Data System (ADS)

    Glombitza, C.; Jaussi, M.; Røy, H.; Jørgensen, B. B.

    2014-12-01

    Volatile fatty acids (VFAs) play important roles as key intermediates in the anaerobic metabolism of subsurface microbial communities. Usually they are present in marine sediment pore water in low concentrations as a result of balanced production and consumption, both occurring in the same sediment zone. Thus their low concentrations represent a steady state condition regulated by either thermodynamics or kinetics. We have developed a novel analytical approach for the parallel measurement of several VFAs directly from marine pore water without any sample pretreatment by the use of a 2-dimensional ion chromatography coupled to mass spectrometry. In a first study we analyzed acetate, formate, and propionate in pore water from sediment cores retrieved from 5 different stations within and offshore of the Godhåbsfjord (Greenland). The sediment cores represent different sedimentological conditions, ranging from a typical marine sedimentation site to a glacier/freshwater dominated site. In addition to VFA concentrations, we measured sulfate concentrations, sulfate reduction rates, and cell abundances. We calculated the Gibbs free energy (ΔG) available for sulfate reduction (SR), as well as the VFA turnover times by the in-situ SR rates. The turnover time for acetate by SR ranged from several hours to days in the top cm of sediment and increased to several hundred years at the bottom of the SR zone. From the associated cell abundances we calculated that the VFA turnover times were significantly longer than the diffusion times of the VFA between individual cells. This shows that VFA consumption in the SR zone, and concomitantly the observed pore water concentrations, are not constrained by diffusion. DG values for SR using acetate were >36 kJ/mol which is significantly above the lower limit for anaerobic microbial energy metabolism. It thus remains unclear what controls the VFA concentrations in the sediment.

  2. The carbon isotope biogeochemistry of acetate from a methanogenic marine sediment

    NASA Technical Reports Server (NTRS)

    Blair, N. E.; Carter, W. D., Jr.

    1992-01-01

    The delta C-13 value of porewater acetate isolated from the anoxic sediments of Cape Lookout Bight (North Carolina) ranged from -17.6 percent in the sulfate reduction zone to -2.8 percent in the underlying methanogenic zone. The large C-13 enrichment in the sulfate-depleted sediments appears to be associated with the dissimilation of acetate to CH4 and CO2. Fractionation factors for that process were estimated to be 1.032 +/- 0.014 and 1.036 +/- 0.019 for the methyl and carboxyl groups. A subsurface maximum in delta C-13 of the total acetate molecule, as well as the methyl and carboxyl carbons at 10-15 cm depth within the sediment column, indicate that changes in the relative rates of acetate cycling pathways occur in the methanogenic zone. The methyl group of the acetate was depleted in C-13 by 7-14 percent relative to the carboxyl moiety. The intramolecular heterogeneity may be the result of both synthetic and catabolic isotope effects.

  3. Nucleic acid based quantitative microbial community analysis in different marine and terrestrial sediments

    NASA Astrophysics Data System (ADS)

    Schippers, A.; Blazejak, A.; Köweker, G.

    2009-12-01

    Sub-seafloor sediments harbour over half of all prokaryotic cells on Earth. This immense cell number is calculated from numerous microscopic cell counts (AODC) in ODP sediment cores. Since AODC can not differentiate between living or dead cells, the population size of living microorganisms and the abundance of different prokaryotic groups are unknown. Recent molecular nucleic acid and biomarker analyses showed that a high proportion of the cells are alive and that the microbial communities of deep marine sediments harbour members of distinct, uncultured bacterial and archaeal lineages. The main objective of our project is the quantification of living prokaryotes in various sediments. Deep sediment samples from the Pacific and the Atlantic Oceans (ODP Legs 201 and 207, IODP Exp. 307 and 308), sediments from the Indian Ocean (RV Sonne 189-2) and the Black Sea (RV Meteor 51/4) as well as terrestrial Chesapeake Bay Sediments (ICDP) were analyzed using Catalyzed Reporter Deposition - Fluorescence In Situ Hybridisation (CARD - FISH) and quantitative, real-time PCR (Q-PCR), targeting either the 16S rRNA gene or the functional genes dsrA, mcrA and aprA to quantify microorganisms of various phylogenetic or physiological groups (e.g. JS1 cluster and Chloroflexi). At all sediment sites, cell numbers decreased with depth, however, the abundance of particular microbial groups varied at different sites and depths. The results indicate that global estimates of the deep biosphere should be reconsidered.

  4. Bioturbation: impact on the marine nitrogen cycle.

    PubMed

    Laverock, Bonnie; Gilbert, Jack A; Tait, Karen; Osborn, A Mark; Widdicombe, Steve

    2011-01-01

    Sediments play a key role in the marine nitrogen cycle and can act either as a source or a sink of biologically available (fixed) nitrogen. This cycling is driven by a number of microbial remineralization reactions, many of which occur across the oxic/anoxic interface near the sediment surface. The presence and activity of large burrowing macrofauna (bioturbators) in the sediment can significantly affect these microbial processes by altering the physicochemical properties of the sediment. For example, the building and irrigation of burrows by bioturbators introduces fresh oxygenated water into deeper sediment layers and allows the exchange of solutes between the sediment and water column. Burrows can effectively extend the oxic/anoxic interface into deeper sediment layers, thus providing a unique environment for nitrogen-cycling microbial communities. Recent studies have shown that the abundance and diversity of micro-organisms can be far greater in burrow wall sediment than in the surrounding surface or subsurface sediment; meanwhile, bioturbated sediment supports higher rates of coupled nitrification-denitrification reactions and increased fluxes of ammonium to the water column. In the present paper we discuss the potential for bioturbation to significantly affect marine nitrogen cycling, as well as the molecular techniques used to study microbial nitrogen cycling communities and directions for future study.

  5. Subdivision of Holocene Baltic sea sediments by their physical properties [Gliederung holozaner ostseesedimente nach physikalischen Eigenschaften

    USGS Publications Warehouse

    Harff, Jan; Bohling, G.C.; Endler, R.; Davis, J.C.; Olea, R.A.

    1999-01-01

    The Holocene sediment sequence of a core taken within the centre of the Eastern Gotland Basin was subdivided into 12 lithostratigraphic units based on MSCL-data (sound velocity, wet bulk density, magnetic susceptibility) using a multivariate classification method. The lower 6 units embrace the sediments until the Litorina transgression, and the upper 6 units subdivide the brackish-marine Litorina- and post-Litorina sediments. The upper lithostratigraphic units reflect a change of anoxic (laminated) and oxic (non-laminated) sediments. By application of a numerical stratigraphic correlation method the zonation was extended laterally onto contiguous sediment cores within the central basin. Consequently the change of anoxic and oxic sediments can be used for a general lithostratigraphic subdivision of sediments of the Gotland Basin. A quantitative criterion based on the sediment-physical lithofacies is added to existing subdivisions of the Holocene in the Baltic Sea.

  6. Sediment Contaminants and Infauna Associated with Recreational Boating Structures in a Multi-Use Marine Park.

    PubMed

    Sim, Vivian X Y; Dafforn, Katherine A; Simpson, Stuart L; Kelaher, Brendan P; Johnston, Emma L

    2015-01-01

    Multi-use marine parks achieve conservation through spatial management of activities. Zoning of marine parks in New South Wales, Australia, includes high conservation areas and special purpose zones (SPZ) where maritime activities are concentrated. Although such measures geographically constrain anthropogenic impacts, we have limited understanding of potential ecological effects. We assessed sediment communities and contaminants adjacent to boating infrastructure (boat ramps, jetties and a marina) in a SPZ from the Clyde Estuary in Batemans Marine Park. Metal concentrations and fines content were elevated at boating structures compared to reference sites. Species richness was higher at sites with boating structures, where capitellid polychaetes and nematodes dominated the communities. Changes associated with boating structures were localised and did not extend beyond breakwalls or to reference sites outside the SPZ. The study highlights the benefits of appropriate zoning in a multi-use marine park and the potential to minimise stress on pristine areas through the application of spatial management.

  7. Sediment Contaminants and Infauna Associated with Recreational Boating Structures in a Multi-Use Marine Park

    PubMed Central

    Sim, Vivian X. Y.; Dafforn, Katherine A.; Simpson, Stuart L.; Kelaher, Brendan P.; Johnston, Emma L.

    2015-01-01

    Multi-use marine parks achieve conservation through spatial management of activities. Zoning of marine parks in New South Wales, Australia, includes high conservation areas and special purpose zones (SPZ) where maritime activities are concentrated. Although such measures geographically constrain anthropogenic impacts, we have limited understanding of potential ecological effects. We assessed sediment communities and contaminants adjacent to boating infrastructure (boat ramps, jetties and a marina) in a SPZ from the Clyde Estuary in Batemans Marine Park. Metal concentrations and fines content were elevated at boating structures compared to reference sites. Species richness was higher at sites with boating structures, where capitellid polychaetes and nematodes dominated the communities. Changes associated with boating structures were localised and did not extend beyond breakwalls or to reference sites outside the SPZ. The study highlights the benefits of appropriate zoning in a multi-use marine park and the potential to minimise stress on pristine areas through the application of spatial management. PMID:26086427

  8. Analysis of marine sediment and lobster hepatopancreas reference materials by instrumental photon activation

    SciTech Connect

    Landsberger, S.; Davidson, W.F.

    1985-01-01

    By use of instrumental photon activation analysis, twelve trace (As, Ba, Cr, Co, Mn, Ni, Pb, Sb, Sr, U, Zn, and Zr) and eight minor (C, Na, Mg, Co, K, Ca, Tl, and Fe) elements were determined in a certified marine sediment standard reference material as well as eight trace (Mn, Ni, Cu, Zn, As, Sr, Cd, and Pb) and four minor (Na, Mg, Cl, and Ca) elements in a certified marine tissue (lobster hepatopancreas) standard reference material. The precision and accuracy of the present results when compared to the accepted values clearly demonstrate the reliability of this nondestructive technique and its applicability to marine environmental or marine geochemical studies. 24 references, 4 figures, 3 tables.

  9. Biogeomorphological implications of microscale interactions between sediment geotechnics and marine benthos: a review

    NASA Astrophysics Data System (ADS)

    Murray, John M. H.; Meadows, Azra; Meadows, Peter S.

    2002-09-01

    At the foundations of biogeomorphological processes in the sea lie interactions between the activities of marine benthic animals and the geotechnical properties of their sedimentary environments. The potential significance of these interactions, which take place at a microscale level of millimetres to metres, for the large-scale geomorphology of the seabed has rarely been appreciated. In the context of this review, large-scale is defined as greater than 50 m to hundreds of kilometres. The present review addresses this link, drawing examples from a wide range of marine environments, including estuaries, the intertidal zone, continental shelves and slopes, and the deep sea. It firstly considers sediment stabilisation, slope failure, sediment mixing, biodeposition, sediment compaction, and hydrodynamic effects. This is followed by a consideration of two extremes of the ecological pyramid—the effects of marine meiofauna and marine vertebrates. The final section draws attention to the central role of faunal mucus and extracellular polymeric material (ECPM) in many of the microscale interactions that we describe. The implications of these microscale biological processes and features are discussed in terms of their influence on and control of the large-scale geomorphology of the seabed.

  10. Effects of dredged sediment disposal on the coastal marine macrobenthic assemblage in Southern Brazil.

    PubMed

    Angonesi, L G; Bemvenuti, C E; Gandra, M S

    2006-05-01

    The aim of this study was to evaluate the deposition impact of dredged material from Patos lagoon estuary on a benthic macroinvertebrate assemblage structure in an adjacent coastal marine area. Nine sampling stations were chosen at random in the disposal area, and nine others in the same way in an adjacent control area. Samples were collected at a 19 m depth before sediment disposal (11 July 2000), during dredging and disposal operations (25 Oct. 2000), and three months thereafter (24 Aug. 2001). Statistical analysis indicated that sampling periods presented similar characteristics in both the control and disposal sites. Disposal of dredged sediment from Patos lagoon had no detectable detrimental effects upon macrobenthic faunal assemblage at the dumping site. This result is attributed both to adaptation of resident biota to dynamic sedimentary conditions and to the fine estuarine sediment dredged, the dispersion of which in the water column might have minimized sediment deposition and consequent damage to the benthic fauna. PMID:16862294

  11. Evaluation of bioremediation potential of three benthic annelids in organically polluted marine sediment.

    PubMed

    Ito, Mana; Ito, Katsutoshi; Ohta, Kohei; Hano, Takeshi; Onduka, Toshimitsu; Mochida, Kazuhiko; Fujii, Kazunori

    2016-11-01

    This study aimed to evaluate the possible remedial effects of three marine benthic annelids on organically polluted sediments from the waters of Hatsukaichi Marina, Hiroshima, Japan. Two polychaetes, Perinereis nuntia and Capitella cf. teleta, and an oligochaete, Thalassodrilides sp., were incubated in sediments for 50 days. Their effects on physicochemical properties such as organic matter (loss on ignition), redox potential (Eh), acid volatile sulfides (AVS), and degradation of polycyclic aromatic hydrocarbons (PAHs) were assessed. The polychaetes P. nuntia and C. cf. teleta significantly increased Eh level and decreased AVS level compared with the oligochaete Thalassodrilides sp. and control (without benthic organisms). Total PAH concentration significantly decreased from the initial level with all three groups; Thalassodrilides sp. had a marked ability to reduce PAHs in sediment. These results indicate that benthic organisms have species-specific remediation properties and ecological functions in organically polluted sediments. PMID:27565306

  12. Evaluation of bioremediation potential of three benthic annelids in organically polluted marine sediment.

    PubMed

    Ito, Mana; Ito, Katsutoshi; Ohta, Kohei; Hano, Takeshi; Onduka, Toshimitsu; Mochida, Kazuhiko; Fujii, Kazunori

    2016-11-01

    This study aimed to evaluate the possible remedial effects of three marine benthic annelids on organically polluted sediments from the waters of Hatsukaichi Marina, Hiroshima, Japan. Two polychaetes, Perinereis nuntia and Capitella cf. teleta, and an oligochaete, Thalassodrilides sp., were incubated in sediments for 50 days. Their effects on physicochemical properties such as organic matter (loss on ignition), redox potential (Eh), acid volatile sulfides (AVS), and degradation of polycyclic aromatic hydrocarbons (PAHs) were assessed. The polychaetes P. nuntia and C. cf. teleta significantly increased Eh level and decreased AVS level compared with the oligochaete Thalassodrilides sp. and control (without benthic organisms). Total PAH concentration significantly decreased from the initial level with all three groups; Thalassodrilides sp. had a marked ability to reduce PAHs in sediment. These results indicate that benthic organisms have species-specific remediation properties and ecological functions in organically polluted sediments.

  13. Exposure of the marine deposit feeder Hydrobia ulvae to sediment associated LAS.

    PubMed

    Mauffret, A; Rico-Rico, A; Temara, A; Blasco, J

    2010-02-01

    Linear Alkylbenzene Sulfonates (LAS) effects (mortality, egestion rate, behaviour) on the marine deposit feeder Hydrobia ulvae were assessed in whole-sediment and water-only systems. The results were combined with a bioenergetic-based kinetic model of exposure pathways to account for the observed toxicity. The 10-d LC50 value based on the freely dissolved fraction was 9.3 times lower in spiked sediment (0.152 +/- 0.001 (95% CI) mg/L) than in water-only (1.390 +/- 0.020 (95% CI) mg/L). Consequently, the actual 10-d LC50 value (208 mg/kg) was overestimated by the Equilibrium Partitioning calculation (1629 mg/kg). This suggests that the sediment associated LAS fraction was bioavailable to the snails. It could also be due to modifications in physiological parameters in absence of sediment, the organism natural substrate.

  14. Development of a chronic sediment toxicity test for marine benthic amphipods

    SciTech Connect

    DeWitt, T.H.; Redmond, M.S.; Sewall, J.E.; Swartz, R.C.

    1992-12-01

    The results of the research effort culminated in the development of a research method for assessing the chronic toxicity of contaminated marine and estuarine sediments using the benthic amphipod, Leptocheirus plumulosus. The first chapter describes the efforts at collecting, handling, and culturing four estuarine amphipods from Chesapeake Bay, including L. plumulosus. This chapter includes maps of the distribution and abundance of these amphipods within Chesapeake Bay and methodologies for establishing cultures of amphipods which could be readily adopted by other laboratories. The second chapter reports the development of acute and chronic sediment toxicity test methods for L. plumulosus, its sensitivity to non-contaminant environmental variables, cadmium, two polynuclear aromatic hydrocarbons, and contaminated sediment from Baltimore Harbor, MD. The third chapter reports the authors attempts to develop a chronic sediment toxicity test with Ampelisca abdita.

  15. Enhancement of nitrate-induced bioremediation in marine sediments contaminated with petroleum hydrocarbons by using microemulsions.

    PubMed

    Zhang, Zhen; Zheng, Guanyu; Lo, Irene M C

    2015-06-01

    The effect of microemulsion on the biodegradation of total petroleum hydrocarbons (TPH) in nitrate-induced bioremediation of marine sediment was investigated in this study. It was shown that the microemulsion formed with non-ionic surfactant polyoxyethylene sorbitan monooleate (Tween 80), 1-pentanol, linseed oil, and either deionized water or seawater was stable when subjected to dilution by seawater. Desorption tests revealed that microemulsion was more effective than the Tween 80 solution or the solution containing Tween 80 and 1-pentanol to desorb TPH from marine sediment. In 3 weeks of bioremediation treatment, the injection of microemulsion and NO3 (-) seems to have delayed the autotrophic denitrification between NO3 (-) and acid volatile sulfide (AVS) in sediment compared to the control with NO3 (-) injection alone. However, after 6 weeks of treatment, the delaying effect of microemulsion on the autotrophic denitrification process was no longer observed. In the meantime, the four injections of microemulsion and NO3 (-) resulted in as high as 29.73 % of TPH degradation efficiency, higher than that of two injections of microemulsion and NO3 (-) or that of four or two injections of NO3 (-) alone. These results suggest that microemulsion can be potentially applied to enhance TPH degradation in the nitrate-induced bioremediation of marine sediment.

  16. Fungal communities from methane hydrate-bearing deep-sea marine sediments in South China Sea.

    PubMed

    Lai, Xintian; Cao, Lixiang; Tan, Hongming; Fang, Shu; Huang, Yali; Zhou, Shining

    2007-12-01

    To elucidate fungal diversity in methane hydrate-bearing deep-sea marine sediments in the South China Sea, internal transcribed spacer (ITS) regions of rRNA genes from five different sediment DNA samples were amplified and phylogenetically analyzed. Total five ITS libraries were constructed and 413 clones selected randomly were grouped into 24 restriction patterns by Amplified Ribosomal DNA Restriction Analysis (ARDRA). ITS sequences of 44 representative clones were determined and compared with the GenBank database using gapped-BLAST. The phylogenetic analysis showed that the ITS sequences (71-97% similarity) were similar to those of Phoma, Lodderomyces, Malassezia, Cryptococcus, Cylindrocarpon, Hortaea, Pichia, Aspergillus and Candida. The remaining sequences were not associated to any known fungi or fungal sequences in the public database. The results suggested that methane hydrate-bearing deep-sea marine sediments harbor diverse fungi. This is the first report on fungal communities from methane hydrate-bearing deep-sea marine sediments in South China Sea.

  17. Constraining magnesium cycling in marine sediments using magnesium isotopes

    NASA Astrophysics Data System (ADS)

    Higgins, J. A.; Schrag, D. P.

    2010-09-01

    Magnesium concentrations in deep-sea sediment pore-fluids typically decrease down core due to net precipitation of dolomite or clay minerals in the sediments or underlying crust. To better characterize and differentiate these processes, we have measured magnesium isotopes in pore-fluids and sediment samples from Ocean Drilling Program sites (1082, 1086, 1012, 984, 1219, and 925) that span a range of oceanographic settings. At all sites, magnesium concentrations decrease with depth. At sites where diagenetic reactions are dominated by the respiration of organic carbon, pore-fluid δ 26Mg values increase with depth by as much as 2‰. Because carbonates preferentially incorporate 24Mg (low δ 26Mg), the increase in pore-fluid δ 26Mg values at these sites is consistent with the removal of magnesium in Mg-carbonate (dolomite). In contrast, at sites where the respiration of organic carbon is not important and/or weatherable minerals are abundant, pore-fluid δ 26Mg values decrease with depth by up to 2‰. The decline in pore-fluid δ 26Mg at these sites is consistent with a magnesium sink that is isotopically enriched relative to the pore-fluid. The identity of this enriched magnesium sink is likely clay minerals. Using a simple 1D diffusion-advection-reaction model of pore-fluid magnesium, we estimate rates of net magnesium uptake/removal and associated net magnesium isotope fractionation factors for sources and sinks at all sites. Independent estimates of magnesium isotope fractionation during dolomite precipitation from measured δ 26Mg values of dolomite samples from sites 1082 and 1012 are very similar to modeled net fractionation factors at these sites, suggesting that local exchange of magnesium between sediment and pore-fluid at these sites can be neglected. Our results indicate that the magnesium incorporated in dolomite is 2.0-2.7‰ depleted in δ 26Mg relative to the precipitating fluid. Assuming local exchange of magnesium is minor at the rest of the

  18. Kinetic parameters for nutrient enhanced crude oil biodegradation in intertidal marine sediments

    PubMed Central

    Singh, Arvind K.; Sherry, Angela; Gray, Neil D.; Jones, D. Martin; Bowler, Bernard F. J.; Head, Ian M.

    2014-01-01

    Availability of inorganic nutrients, particularly nitrogen and phosphorous, is often a primary control on crude oil hydrocarbon degradation in marine systems. Many studies have empirically determined optimum levels of inorganic N and P for stimulation of hydrocarbon degradation. Nevertheless, there is a paucity of information on fundamental kinetic parameters for nutrient enhanced crude oil biodegradation that can be used to model the fate of crude oil in bioremediation programmes that use inorganic nutrient addition to stimulate oil biodegradation. Here we report fundamental kinetic parameters (Ks and qmax) for nitrate- and phosphate-stimulated crude oil biodegradation under nutrient limited conditions and with respect to crude oil, under conditions where N and P are not limiting. In the marine sediments studied, crude oil degradation was limited by both N and P availability. In sediments treated with 12.5 mg/g of oil but with no addition of N and P, hydrocarbon degradation rates, assessed on the basis of CO2 production, were 1.10 ± 0.03 μmol CO2/g wet sediment/day which were comparable to rates of CO2 production in sediments to which no oil was added (1.05 ± 0.27 μmol CO2/g wet sediment/day). When inorganic nitrogen was added alone maximum rates of CO2 production measured were 4.25 ± 0.91 μmol CO2/g wet sediment/day. However, when the same levels of inorganic nitrogen were added in the presence of 0.5% P w/w of oil (1.6 μmol P/g wet sediment) maximum rates of measured CO2 production increased more than four-fold to 18.40 ± 1.04 μmol CO2/g wet sediment/day. Ks and qmax estimates for inorganic N (in the form of sodium nitrate) when P was not limiting were 1.99 ± 0.86 μmol/g wet sediment and 16.16 ± 1.28 μmol CO2/g wet sediment/day respectively. The corresponding values for P were 63 ± 95 nmol/g wet sediment and 12.05 ± 1.31 μmol CO2/g wet sediment/day. The qmax values with respect to N and P were not significantly different (P < 0.05). When N and P

  19. Geochemical Screening of Contaminated Marine and Estuarine Sediments

    NASA Astrophysics Data System (ADS)

    Kruge, M. A.

    2004-05-01

    Waterways near urban centers have been subject to pollution by human activities for centuries. This process greatly intensified with the advent of the Industrial Revolution and the attendant exponential population increase in coastal areas. The co-occurrence of port facilities for ocean-going vessels, large factories, major power generating stations, dense automotive transportation networks, and massive wastewater outfalls, all in compact geographical areas, has produced severe environmental stress. In recent decades, the growing awareness of the seriousness of coastal urban environmental degradation has inspired intensive efforts at pollution prevention and remediation. To better understand pollution dynamics over time in an aquatic urban setting, a program of intensive sampling and analysis leading to the creation of geographic information systems (GIS) would be desirable. Chemical evaluation of sediments for pollution remains a costly and time-consuming procedure, particularly for organic analysis. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) offers a practical alternative for rapid, inexpensive molecular organic analysis, simply employing milligram quantities of dry, whole sediment. The compounds detected comprise an information-rich mixture of thermally extractable components and the products of the thermal decomposition of (bio)polymers present in the sample. These include PAHs, petroleum-derived hopanes, organonitrogen compounds, and linear alkylbenzenes, as illustrated with examples from Long Island Sound and the Passaic River (USA) and Barcelona harbor (Spain).

  20. Formation of natural gas hydrates in marine sediments. Gas hydrate growth and stability conditioned by host sediment properties

    USGS Publications Warehouse

    Clennell, M.B.; Henry, P.; Hovland, M.; Booth, J.S.; Winters, W.J.; Thomas, M.

    2000-01-01

    The stability conditions of submarine gas hydrates (methane clathrates) are largely dictated by pressure, temperature, gas composition, and pore water salinity. However, the physical properties and surface chemistry of the host sediments also affect the thermodynamic state, growth kinetics, spatial distributions, and growth forms of clathrates. Our model presumes that gas hydrate behaves in a way analogous to ice in the pores of a freezing soil, where capillary forces influence the energy balance. Hydrate growth is inhibited within fine-grained sediments because of the excess internal phase pressure of small crystals with high surface curvature that coexist with liquid water in small pores. Therefore, the base of gas hydrate stability in a sequence of fine sediments is predicted by our model to occur at a lower temperature, and so nearer to the seabed than would be calculated from bulk thermodynamic equilibrium. The growth forms commonly observed in hydrate samples recovered from marine sediments (nodules, sheets, and lenses in muds; cements in sand and ash layers) can be explained by a requirement to minimize the excess of mechanical and surface energy in the system.

  1. Cobalt and marine redox evolution

    NASA Astrophysics Data System (ADS)

    Swanner, Elizabeth D.; Planavsky, Noah J.; Lalonde, Stefan V.; Robbins, Leslie J.; Bekker, Andrey; Rouxel, Olivier J.; Saito, Mak A.; Kappler, Andreas; Mojzsis, Stephen J.; Konhauser, Kurt O.

    2014-03-01

    Cobalt (Co) is a bio-essential trace element and limiting nutrient in some regions of the modern oceans. It has been proposed that Co was more abundant in poorly ventilated Precambrian oceans based on the greater utilization of Co by anaerobic microbes relative to plants and animals. However, there are few empirical or theoretical constraints on the history of seawater Co concentrations. Herein, we present a survey of authigenic Co in marine sediments (iron formations, authigenic pyrite and bulk euxinic shales) with the goal of tracking changes in the marine Co reservoir throughout Earth's history. We further provide an overview of the modern marine Co cycle, which we use as a platform to evaluate how changes in the redox state of Earth's surface were likely to have affected marine Co concentrations. Based on sedimentary Co contents and our understanding of marine Co sources and sinks, we propose that from ca. 2.8 to 1.8 Ga the large volume of hydrothermal fluids circulating through abundant submarine ultramafic rocks along with a predominantly anoxic ocean with a low capacity for Co burial resulted in a large dissolved marine Co reservoir. We tentatively propose that there was a decrease in marine Co concentrations after ca. 1.8 Ga resulting from waning hydrothermal Co sources and the expansion of sulfide Co burial flux. Changes in the Co reservoir due to deep-water ventilation in the Neoproterozoic, if they occurred, are not resolvable with the current dataset. Rather, Co enrichments in Phanerozoic euxinic shales deposited during ocean anoxic events (OAE) indicate Co mobilization from expanded anoxic sediments and enhanced hydrothermal sources. A new record of marine Co concentrations provides a platform from which we can reevaluate the role that environmental Co concentrations played in shaping biological Co utilization throughout Earth's history.

  2. Landslide-dammed paleolake perturbs marine sedimentation and drives genetic change in anadromous fish

    PubMed Central

    Mackey, Benjamin H.; Roering, Joshua J.; Lamb, Michael P.

    2011-01-01

    Large bedrock landslides have been shown to modulate rates and processes of river activity by forming dams, forcing upstream aggradation of water and sediment, and generating catastrophic outburst floods. Less apparent is the effect of large landslide dams on river ecosystems and marine sedimentation. Combining analyses of 1-m resolution topographic data (acquired via airborne laser mapping) and field investigation, we present evidence for a large, landslide-dammed paleolake along the Eel River, CA. The landslide mass initiated from a high-relief, resistant outcrop which failed catastrophically, blocking the Eel River with an approximately 130-m-tall dam. Support for the resulting 55-km-long, 1.3-km3 lake includes subtle shorelines cut into bounding terrain, deltas, and lacustrine sediments radiocarbon dated to 22.5 ka. The landslide provides an explanation for the recent genetic divergence of local anadromous (ocean-run) steelhead trout (Oncorhynchus mykiss) by blocking their migration route and causing gene flow between summer run and winter run reproductive ecotypes. Further, the dam arrested the prodigious flux of sediment down the Eel River; this cessation is recorded in marine sedimentary deposits as a 10-fold reduction in deposition rates of Eel-derived sediment and constitutes a rare example of a terrestrial event transmitted through the dispersal system and recorded offshore. PMID:22084068

  3. Landslide-dammed paleolake perturbs marine sedimentation and drives genetic change in anadromous fish.

    PubMed

    Mackey, Benjamin H; Roering, Joshua J; Lamb, Michael P

    2011-11-22

    Large bedrock landslides have been shown to modulate rates and processes of river activity by forming dams, forcing upstream aggradation of water and sediment, and generating catastrophic outburst floods. Less apparent is the effect of large landslide dams on river ecosystems and marine sedimentation. Combining analyses of 1-m resolution topographic data (acquired via airborne laser mapping) and field investigation, we present evidence for a large, landslide-dammed paleolake along the Eel River, CA. The landslide mass initiated from a high-relief, resistant outcrop which failed catastrophically, blocking the Eel River with an approximately 130-m-tall dam. Support for the resulting 55-km-long, 1.3-km(3) lake includes subtle shorelines cut into bounding terrain, deltas, and lacustrine sediments radiocarbon dated to 22.5 ka. The landslide provides an explanation for the recent genetic divergence of local anadromous (ocean-run) steelhead trout (Oncorhynchus mykiss) by blocking their migration route and causing gene flow between summer run and winter run reproductive ecotypes. Further, the dam arrested the prodigious flux of sediment down the Eel River; this cessation is recorded in marine sedimentary deposits as a 10-fold reduction in deposition rates of Eel-derived sediment and constitutes a rare example of a terrestrial event transmitted through the dispersal system and recorded offshore.

  4. Comparison of four chronic sediment toxicity tests using selected marine/estuarine tests species

    SciTech Connect

    Sims, I.; Fleming, R.

    1995-12-31

    Several draft standard guidelines exist for acute marine/estuarine sediment bioassays which measure lethality over a 4 to 14 day exposure period. Although these are very useful tools for certain applications, such tests may not be useful for discriminating between sediments with the low levels of contaminants most likely to be found in UK estuaries. For this application, chronic sediment bioassays are required which allow the measurement of both lethal and sublethal effects (growth, development and reproduction). Some chronic bioassays are currently being developed for estuarine sediments by workers in Europe, America and Canada. The objectives of the study presented here were to compare four bioassays, currently in development, in terms of their sensitivity to sediment-bound lindane and to differences in particle size. The test species selected for the study were Corophium volutator, Arenicola marina, Macoma Balthica and Neanthes arenaceodentata. Three sediment types were used: high, medium and low percentage of fine material, These were achieved using mixtures of silica sand and a fine, natural, estuarine sediment, and spiked with lindane using a spiking protocol developed at WRc. The results of the study will be presented.

  5. Comparison of marine gas hydrates in sediments of an active and passive continental margin

    USGS Publications Warehouse

    Kvenvolden, K.A.

    1985-01-01

    Two sites of the Deep Sea Drilling Project in contrasting geologic settings provide a basis for comparison of the geochemical conditions associated with marine gas hydrates in continental margin sediments. Site 533 is located at 3191 m water depth on a spit-like extension of the continental rise on a passive margin in the Atlantic Ocean. Site 568, at 2031 m water depth, is in upper slope sediment of an active accretionary margin in the Pacific Ocean. Both sites are characterized by high rates of sedimentation, and the organic carbon contents of these sediments generally exceed 0.5%. Anomalous seismic reflections that transgress sedimentary structures and parallel the seafloor, suggested the presence of gas hydrates at both sites, and, during coring, small samples of gas hydrate were recovered at subbottom depths of 238m (Site 533) and 404 m (Site 568). The principal gaseous components of the gas hydrates wer methane, ethane, and CO2. Residual methane in sediments at both sites usually exceeded 10 mll-1 of wet sediment. Carbon isotopic compositions of methane, CO2, and ??CO2 followed parallel trends with depth, suggesting that methane formed mainly as a result of biological reduction of oxidized carbon. Salinity of pore waters decreased with depth, a likely result of gas hydrate formation. These geochemical characteristics define some of the conditions associated with the occurrence of gas hydrates formed by in situ processes in continental margin sediments. ?? 1984.

  6. Preliminary mapping of void fractions and sound speeds in gassy marine sediments from subbottom profiles.

    PubMed

    Leighton, T G; Robb, G B N

    2008-11-01

    Bubbles of gas (usually methane) in marine sediments affect the load-bearing properties of the seabed and act as a natural reservoir of "greenhouse" gas. This paper describes a simple method which can be applied to historical and future subbottom profiles to infer bubble void fractions and map the vertical and horizontal distributions of gassy sediments, and the associated sound speed perturbations, even with single-frequency insonification. It operates by identifying horizontal features in the geology and interpreting any perceived change of depth in these as a bubble-mediated change in sound speed. PMID:19045684

  7. Toxicological effects of short-term resuspension of metal-contaminated freshwater and marine sediments.

    PubMed

    Fetters, Kyle J; Costello, David M; Hammerschmidt, Chad R; Burton, G Allen

    2016-03-01

    Sediments in navigation-dominated waterways frequently are contaminated with a variety of particle-associated pollutants and are subject to frequent short-term resuspension events. There is little information documenting whether resuspension of metal-contaminated sediments has adverse ecological effects on resident aquatic organisms. Using a novel laboratory approach, the authors examined the mobilization of Zn, Cu, Cd, Pb, Ni, and Cr during resuspension of 1 freshwater and 2 coastal marine sediments and whether resuspension and redeposition resulted in toxicity to model organisms. Sediment flux exposure chambers were used to resuspend metal-contaminated sediments from 1 site in Lake DePue, Illinois (USA), and 2 sites in Portsmouth Naval Shipyard, Maine (USA). Short-term (4-h) resuspension of sediment at environmentally relevant suspended particulate matter concentrations (<1 g/L) resulted in metal mobilization to water that was sediment and metal specific. Overall, the net release of metals from suspended particles was limited, likely because of scavenging by organic matter and Fe oxides that formed during sediment interaction with oxic water. Minimal toxicity to organisms (survival of Hyalella azteca and Daphnia magna; survival, growth, and tissue metal concentration of Neanthes arenaceodentata; bioluminescence of Pyrocystis lunula) was observed during 4-h exposure to resuspended sediments and during 4-d to 10-d post-exposure recovery periods in uncontaminated water. Redeposited suspended particles exhibited increased metal bioavailability and toxicity to H. azteca, highlighting the potential for adverse ecological impacts because of changes in metal speciation. It is important to consider interactions between organisms' life histories and sediment disturbance regimes when assessing risks to ecosystems.

  8. Thermal alteration experiments on organic matter from recent marine sediments in relation to petroleum genesis

    NASA Technical Reports Server (NTRS)

    Ishiwatari, R.; Ishiwatari, M.; Rohrback, B. G.; Kaplan, I. R.

    1977-01-01

    Three fractions of organic matter: lipid (benzene:methanol-extractable), humic acid (alkali-extractable) and kerogen (residue) were extracted from a young marine sediment (Tanner Basin, offshore southern California) and heated for different times (5-116 hr) and temperatures (150-410 C). The volatile (gases) and liquid products, as well as residual material, were then analyzed. On a weight basis, the lipid fraction produced 58% of the total identified n-alkanes, the kerogen fraction 41%, and the humic acid less than 1%. The volatiles produced by heating the lipid and humic acid fractions were largely CO2 and water, whereas those produced from heated kerogen also included methane, hydrogen gas and small amounts of C2-C4 hydrocarbons. A mechanism for hydrocarbon production due to the thermal alteration of organic constituents of marine sediment is discussed.

  9. Modelling acoustic scattering, sound speed, and attenuation in gassy soft marine sediments.

    PubMed

    Mantouka, A; Dogan, H; White, P R; Leighton, T G

    2016-07-01

    A model for nonlinear gas bubble pulsation in marine sediments is presented. This model is then linearized to determine the resonance frequency and the damping terms for linear radial oscillations. The linear model is then used to predict the effects that such bubble pulsations will have on the sound speed and attenuation of acoustic waves propagating in gassy marine sediment. The results are compared for monodisperse populations against the predictions of a model of Anderson and Hampton and, furthermore, the additional abilities of the model introduced in this paper are discussed. These features include the removal of the sign ambiguities in the expressions, the straightforward implementation for acoustic propagation through polydisperse bubble populations, the capability to estimate bubble size distributions through a full acoustic inversion, and the capability to predict nonlinear effects. PMID:27475152

  10. A note on the relationships between organic matter and some geotechnical properties of a marine sediment

    USGS Publications Warehouse

    1986-01-01

    Comparing the results of regression analyses from this and several similar studies shows that although there is good qualitative agreement, there are quantitative inconsistencies. In particular there is considerable overall variability in the regression coefficients. Among studies on marine sediments the inconsistencies are less pronounced, yet still evident. The increase in liquid limit as organic carbon increased by 1 % sediment dry weight ranged from 9 to 28% water content; in the plastic limit the range was from 4 to 18%. However, in these marine studies regression coefficients are relatively close in value in some cases, levels of significance of the regressions are high in most cases, and in all cases the relationships appear to be linear over the range of organic carbon percentage studied. Finally, we believe that a relatively clear relationship between plasticity and organic carbon begins to emerge when the latter exceeds a value of 2%.

  11. Lead isotopes in Southern Ocean marine sediments: implications for paleoclimatic provenance and seawater studies

    NASA Astrophysics Data System (ADS)

    Cook, C. P.; Martin, E. E.

    2014-12-01

    Lead (Pb) isotopes in detrital marine sediments and authigenic oxide coatings have proven useful in reconstructing past changes in continental weathering of glaciated continents and ocean circulation. This approach is under-utilised in the Southern Ocean, despite uncertainties about the evolution of Antarctica's ice sheets and oceanographic changes in this region throughout the Cenozoic. Lead isotopes in sediments are controlled by the mineralogy and age of their bedrock sources, making them an ideal tool to trace changes in Southern Ocean sediment provenance associated with onland erosion patterns (and ice sheet variability), and ocean circulation. However, core-top mapping of Pb isotope signatures of detrital marine sediments in this region is non-existent. We present new Pb isotope data for acid-digested <63µm and bulk Late Holocene sediments from 40 cores located in the East Antarctic sector of Southern Ocean. Results demonstrate that, similar to existing Nd and Sr core-top surveys, distinct provenance sectors can be seen in sediments proximal to the continent, due to the geological characteristics of bedrock sources along the margin. A striking N-S trend is also evident, with distal sediments characterised by less radiogenic isotopic signatures, likely associated with a decrease in radiogenic Pb-bearing minerals with increasing distance from the continental margin. This pattern suggests that Pb isotopes in marine sediments may be useful in reconstructing past provenance trends associated with ice sheet change, and migrations of Southern Ocean frontal positions. In addition, we will present new seawater Pb isotope data from reductive leaching of authigenic coatings of these same sediments, permitting for Late Holocene Pb isotope seawater mapping of the Southern Ocean. To ensure we measured the true seawater signal, we adapted established sequential leaching procedures to minimise detrital contamination, and monitored leachate compositions with Nd isotopes, and

  12. Quantifying the degradation of organic matter in marine sediments: A review and synthesis

    NASA Astrophysics Data System (ADS)

    Arndt, Sandra; Jørgensen, B. B.; LaRowe, D. E.; Middelburg, J. J.; Pancost, R. D.; Regnier, P.

    2013-08-01

    Quantifying the rates of biogeochemical processes in marine sediments is essential for understanding global element cycles and climate change. Because organic matter degradation is the engine behind benthic dynamics, deciphering the impact that various forces have on this process is central to determining the evolution of the Earth system. Therefore, recent developments in the quantitative modeling of organic matter degradation in marine sediments are critically reviewed. The first part of the review synthesizes the main chemical, biological and physical factors that control organic matter degradation in sediments while the second part provides a general review of the mathematical formulations used to model these processes and the third part evaluates their application over different spatial and temporal scales. Key transport mechanisms in sedimentary environments are summarized and the mathematical formulation of the organic matter degradation rate law is described in detail. The roles of enzyme kinetics, bioenergetics, temperature and biomass growth in particular are highlighted. Alternative model approaches that quantify the degradation rate constant are also critically compared. In the third part of the review, the capability of different model approaches to extrapolate organic matter degradation rates over a broad range of temporal and spatial scales is assessed. In addition, the structure, functions and parameterization of more than 250 published models of organic matter degradation in marine sediments are analyzed. The large range of published model parameters illustrates the complex nature of organic matter dynamics, and, thus, the limited transferability of these parameters from one site to another. Compiled model parameters do not reveal a statistically significant correlation with single environmental characteristics such as water depth, deposition rate or organic matter flux. The lack of a generic framework that allows for model parameters to be

  13. 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

  14. METAL-COLLOID PARTITIONING IN ARTIFICIAL INTERSTITIAL WATERS OF MARINE SEDIMENTS: INFLUENCES OF SALINITY, PH AND COLLOIDAL ORGANIC CARBON CONCENTRATION

    EPA Science Inventory

    For decades, heavy metals have been deposited into marine sediments as a result of anthropogenic activities. Depending on their bioavailability, these metals may represent a risk to benthic organisms. Dissolved interstitial water metal concentrations have been shown to be better ...

  15. IMPORTANCE OF BLACK CARBON IN DISTRIBUTION AND BIOACCUMULATION MODELS OF POLYCYCLIC AROMATIC HYDROCARBONS IN CONTAMINATED MARINE SEDIMENTS

    EPA Science Inventory

    The roles and relative importance of nonpyrogenic organic carbon (NPOC) and black carbon (BC) as binding phases of polycyclic aromatic hydrocarbons (PAHs) were assessed by their ability to estimate pore water concentrations and biological uptake in various marine sediments. Sedim...

  16. Manual for the geochemical analyses of marine sediments and suspended particulate matter

    NASA Astrophysics Data System (ADS)

    Loring, D. H.; Rantala, R. T. T.

    1992-07-01

    Accurate and precise sampling and analytical procedures are essential in environmental geochemical studies. This report provides a detailed description of the techniques and analytical procedures for sampling, grain size determinations, and for precise and accurate AAS determination of the major and trace metals in marine sediments and suspended particulate matter. In addition, it describes the procedures for the chemical partition of the metals, determination of readily oxidizable organic matter, and calcium carbonate. A separate section discusses the normalization of trace metal data.

  17. Stereochemistry of amino acids in surface samples of a marine sediment

    USGS Publications Warehouse

    Pollock, G.E.; Kvenvolden, K.A.

    1978-01-01

    In two surface samples of marine sediment, the percentages of d-alanine and d-aspartic acid are significantly higher than the other d-amino acids and are similar to the range found in soils. The percentage of d-glutamic acid is also higher than the other amino acids but less than d-alanine and d-aspartic acid. These d-amino acids may come mainly from bacteria. ?? 1978.

  18. Stereochemistry of amino acids in surface samples of a marine sediment

    NASA Technical Reports Server (NTRS)

    Pollock, G. E.; Kvenvolden, K. A.

    1978-01-01

    In two surface samples of marine sediment, the percentages of D-alanine and D-aspartic acid are significantly higher than the other D-amino acids and are similar to the range found in soils. The percentage of D-glutamic acid is also higher than the other amino acids but less than D-alanine and D-aspartic acid. These D-amino acids may come mainly from bacteria.

  19. Seismic peak amplitude as a predictor of TOC content in shallow marine sediments

    NASA Astrophysics Data System (ADS)

    Neto, Arthur Ayres; Mota, Bruno Bourguignon; Belem, André Luiz; Albuquerque, Ana Luiza; Capilla, Ramsés

    2016-10-01

    Acoustic remote sensing is a highly effective tool for exploring the seafloor of both deep and shallow marine settings. Indeed, the acoustic response depends on several physicochemical factors such as sediment grain size, bulk density, water content, and mineralogy. The objective of the present study is to assess the suitability of seismic peak amplitude as a predictor of total organic carbon (TOC) content in shallow marine sediments, based on data collected in the Cabo Frio mud belt in an upwelling zone off southeastern Brazil. These comprise records of P-wave velocity ( V P) along 680 km of high-resolution single-channel seismic surveys, combined with analyses of grain size, wet bulk density, absolute water content and TOC content for four piston-cores. TOC contents of sediments from 13 box-cores served to validate the methodology. The results show well-defined positive correlations between TOC content and mean grain size (phi scale) as well as absolute water content, and negative correlations with V P, wet bulk density, and acoustic impedance. These relationships yield a regression equation by which TOC content can be satisfactorily predicted on the basis of acoustic impedance for this region: y = - 4.84 ln( x) + 40.04. Indeed, the derived TOC contents differ by only 5% from those determined by geochemical analysis. After appropriate calibration, acoustic impedance can thus be conveniently used as a predictor of large-scale spatial distributions of organic carbon enrichment in marine sediments. This not only contributes to optimizing scientific project objectives, but also enhances the cost-effectiveness of marine surveys by greatly reducing the ship time commonly required for grid sampling.

  20. Seismic peak amplitude as a predictor of TOC content in shallow marine sediments

    NASA Astrophysics Data System (ADS)

    Neto, Arthur Ayres; Mota, Bruno Bourguignon; Belem, André Luiz; Albuquerque, Ana Luiza; Capilla, Ramsés

    2016-04-01

    Acoustic remote sensing is a highly effective tool for exploring the seafloor of both deep and shallow marine settings. Indeed, the acoustic response depends on several physicochemical factors such as sediment grain size, bulk density, water content, and mineralogy. The objective of the present study is to assess the suitability of seismic peak amplitude as a predictor of total organic carbon (TOC) content in shallow marine sediments, based on data collected in the Cabo Frio mud belt in an upwelling zone off southeastern Brazil. These comprise records of P-wave velocity (V P) along 680 km of high-resolution single-channel seismic surveys, combined with analyses of grain size, wet bulk density, absolute water content and TOC content for four piston-cores. TOC contents of sediments from 13 box-cores served to validate the methodology. The results show well-defined positive correlations between TOC content and mean grain size (phi scale) as well as absolute water content, and negative correlations with V P, wet bulk density, and acoustic impedance. These relationships yield a regression equation by which TOC content can be satisfactorily predicted on the basis of acoustic impedance for this region: y = - 4.84 ln(x) + 40.04. Indeed, the derived TOC contents differ by only 5% from those determined by geochemical analysis. After appropriate calibration, acoustic impedance can thus be conveniently used as a predictor of large-scale spatial distributions of organic carbon enrichment in marine sediments. This not only contributes to optimizing scientific project objectives, but also enhances the cost-effectiveness of marine surveys by greatly reducing the ship time commonly required for grid sampling.

  1. Reductive dechlorination of tetrachloroethene in marine sediments: Biodiversity and dehalorespiring capabilities of the indigenous microbes.

    PubMed

    Matturro, B; Presta, E; Rossetti, S

    2016-03-01

    Chlorinated compounds pose environmental concerns due to their toxicity and wide distribution in several matrices. Microorganisms specialized in leading anaerobic reductive dechlorination (RD) processes, including Dehalococcoides mccartyi (Dhc), are able to reduce chlorinated compounds to harmless products or to less toxic forms. Here we report the first detailed study dealing with the RD potential of heavy polluted marine sediment by evaluating the biodegradation kinetics together with the composition, dynamics and activity of indigenous microbial population. A microcosm study was conducted under strictly anaerobic conditions on marine sediment collected near the marine coast of Sarno river mouth, one of the most polluted river in Europe. Tetrachloroethene (PCE), used as model pollutant, was completely converted to ethene within 150 days at reductive dechlorination rate equal to 0.016 meq L(-1) d(-1). Consecutive spikes of PCE allowed increasing the degradation kinetics up to 0.1 meq L(-1)d(-1) within 20 days. Strictly anaerobiosis and repeated spikes of PCE stimulated the growth of indigenous Dhc cells (growth yield of ~7.0 E + 07 Dhc cells per μM Cl(-1) released). Dhc strains carrying the reductive dehalogenase genes tceA and vcrA were detected in the original marine sediment and their number increased during the treatment as demonstrated by the high level of tceA expression at the end of the microcosm study (2.41 E + 05 tceA gene transcripts g(-1)). Notably, the structure of the microbial communities was fully described by Catalysed Reporter Deposition Fluorescence In Situ Hybridization (CARD-FISH) as wells as the dynamics of the dechlorinating bacteria during the microcosms operation. Interestingly, a direct role of Dhc cells was ascertained suggesting the existence of strains adapted at salinity conditions. Additionally, non-Dhc Chloroflexi were retrieved in the original sediment and were kept stable over time suggesting their likely flanking role of the RD

  2. Distinct iron isotopic signatures and supply from marine sediment dissolution.

    PubMed

    Homoky, William B; John, Seth G; Conway, Tim M; Mills, Rachel A

    2013-01-01

    Oceanic iron inputs must be traced and quantified to learn how they affect primary productivity and climate. Chemical reduction of iron in continental margin sediments provides a substantial dissolved flux to the oceans, which is isotopically lighter than the crust, and so may be distinguished in seawater from other sources, such as wind-blown dust. However, heavy iron isotopes measured in seawater have recently led to the proposition of another source of dissolved iron from 'non-reductive' dissolution of continental margins. Here we present the first pore water iron isotope data from a passive-tectonic and semi-arid ocean margin (South Africa), which reveals a smaller and isotopically heavier flux of dissolved iron to seawater than active-tectonic and dysoxic continental margins. These data provide in situ evidence of non-reductive iron dissolution from a continental margin, and further show that geological and hydro-climatic factors may affect the amount and isotopic composition of iron entering the ocean.

  3. Bacillus oceanisediminis sp. nov., isolated from marine sediment.

    PubMed

    Zhang, Jianli; Wang, Jiewei; Fang, Caiyuan; Song, Fei; Xin, Yuhua; Qu, Lei; Ding, Kai

    2010-12-01

    A Gram-stain-positive, spore-forming, rod-shaped and aerobic bacterium was isolated from a sediment sample from the South Sea in China. The isolate, designated H2(T), grew at 4-45 °C (optimum 37 °C) and pH 6-10 (optimum pH 7.0). The cell-wall peptidoglycan contained meso-diaminopimelic acid. The major isoprenoid quinone was MK-7 and the polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and an unknown aminophospholipid. The major fatty acid was iso-C(15 : 0). The genomic DNA G+C content of strain H2(T) was 44.8mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolate formed a monophyletic clade with Bacillus firmus IAM 12464(T). DNA-DNA relatedness between the isolate and B. firmus ATCC 14575(T) was low (27.5 %). Strain H2(T) also had a phenotypic profile that readily distinguished it from its closest phylogenetic neighbours. It is evident from the combination of genotypic and phenotypic data that the organism should be classified in a novel species of the genus Bacillus, for which the name Bacillus oceanisediminis sp. nov. is proposed. The type strain is H2(T) (=CGMCC 1.10115(T) =JCM 16506(T)).

  4. Extension of 239+240Pu sediment geochronology to coarse-grained marine sediments

    USGS Publications Warehouse

    Kuehl, Steven A.; Ketterer, Michael E.; Miselis, Jennifer L.

    2012-01-01

    Sediment geochronology of coastal sedimentary environments dominated by sand has been extremely limited because concentrations of natural and bomb-fallout radionuclides are often below the limit of measurement using standard techniques. ICP-MS analyses of 239+240Pu from two sites representative of traditionally challenging (i.e., low concentration) environments provide a "proof of concept" and demonstrate a new application for bomb-fallout radiotracers in the study of sandy shelf-seabed dynamics. A kasten core from the New Zealand shelf in the Southern Hemisphere (low fallout), and a vibracore from the sandy nearshore of North Carolina (low particle surface area) both reveal measurable 239+240Pu activities at depth. In the case of the New Zealand site, independently verified steady-state sedimentation results in a 239+240Pu profile that mimics the expected atmospheric fallout. The depth profile of 239+240Pu in the North Carolina core is more uniform, indicating significant sediment resuspension, which would be expected in this energetic nearshore environment. This study, for the first time, demonstrates the utility of 239+240Pu in the study of sandy environments, significantly extending the application of bomb-fallout isotopes to coarse-grained sediments, which compose the majority of nearshore regions.

  5. A novel approach to the assess biotic oxygen consumption in marine sediment communities

    NASA Astrophysics Data System (ADS)

    Baranov, Victor; Queiros, Ana; Widdicombe, Stephen; Stephens, Nick; Lessin, Gennadi; Krause, Stefan; Lewandowski, Joerg

    2016-04-01

    Bioturbation , the mixing of the sediment matrix by burrowing animals impacts sediment metabolism, including respiration through redistribution of particulate organics, changes in bacterial biota diversity and acitivity, as well as via burrowing fauna's own metabolism. Bioturbation, reflecting faunal activity, is also a proxy for the general sedimentary ecosystem health, and can be impacted by many of emerging marine environmental issues such as ocean acidification, warming and the occurrence of heat waves. Sedimentary oxygen consumption is often taken as a proxy for the activity of bioturbating fauna, but determining baselines can be difficult because of the confounding effects of other fauna and microbes present in sediments, as well as irnorganic processes that consume oxygen. Limitations therefore exist in current methodologies, and numerous confounding factors are hampering progress in this area. Here, we present novel method for the assessment of sediment respiration which is expected to be affected only by the biogenic oxygen consumption (namely aerobic respiration). As long as tracer reduction "immune" to inorganic oxygen consumption, so that measurements using this method can be used, alongside traditional methods, to decouple biological respiration from inorganic oxygen consumption reactions. The tracer is easily detectable, non-toxic and can be applied in systems with constant oxygen supply. The latter allow for incubation without the need to to work with unsealed experimental units, bringing procedural advantage over traditional methods. Consequently assessed bioturbating fauna is not exposed to hypoxia and additional stress. Here, we had applied system for the first time to investigate impacts of a common North-Atlantic bioturbator, the brittle star Amphiura filiformis, - on respiration of marine sediments. Two series of experiments were conducted with animals and sediment collected from Cawsand Bay, Plymouth, UK Preliminary results show that tracer

  6. Distribution and sources of organic matter in surface marine sediments across the North American Arctic margin

    NASA Astrophysics Data System (ADS)

    Goñi, Miguel A.; O'Connor, Alison E.; Kuzyk, Zou Zou; Yunker, Mark B.; Gobeil, Charles; Macdonald, Robie W.

    2013-09-01

    As part of the International Polar Year research program, we conducted a survey of surface marine sediments from box cores along a section extending from the Bering Sea to Davis Strait via the Canadian Archipelago. We used bulk elemental and isotopic compositions, together with biomarkers and principal components analysis, to elucidate the distribution of marine and terrestrial organic matter in different regions of the North American Arctic margin. Marked regional contrasts were observed in organic carbon loadings, with the highest values (≥1 mg C m-2 sediment) found in sites along Barrow Canyon and the Chukchi and Bering shelves, all of which were characterized by sediments with low oxygen exposure, as inferred from thin layers (<2 cm) of Mn oxihydroxides. We found strong regional differences in inorganic carbon concentrations, with sites from the Canadian Archipelago and Lancaster Sound displaying elevated values (2-7 wt %) and highly depleted 14C compositions consistent with inputs from bedrock carbonates. Organic carbon:nitrogen ratios, stable carbon isotopes, and terrigenous organic biomarkers (lignin phenols and cutin acids) all indicate marked regional differences in the proportions of marine and terrigenous organic matter present in surface sediments. Regions such as Barrow Canyon and the Mackenzie River shelf were characterized by the highest contributions of land-derived organic matter, with compositional characteristics that suggested distinct sources and provenance. In contrast, sediments from the Canadian Archipelago and Davis Strait had the smallest contributions of terrigenous organic matter and the lowest organic carbon loadings indicative of a high degree of post-depositional oxidation.

  7. Marine coastal sediments microbial hydrocarbon degradation processes: contribution of experimental ecology in the omics’era

    PubMed Central

    Cravo-Laureau, Cristiana; Duran, Robert

    2014-01-01

    Coastal marine sediments, where important biological processes take place, supply essential ecosystem services. By their location, such ecosystems are particularly exposed to human activities as evidenced by the recent Deepwater Horizon disaster. This catastrophe revealed the importance to better understand the microbial processes involved on hydrocarbon degradation in marine sediments raising strong interests of the scientific community. During the last decade, several studies have shown the key role played by microorganisms in determining the fate of hydrocarbons in oil-polluted sediments but only few have taken into consideration the whole sediment’s complexity. Marine coastal sediment ecosystems are characterized by remarkable heterogeneity, owning high biodiversity and are subjected to fluctuations in environmental conditions, especially to important oxygen oscillations due to tides. Thus, for understanding the fate of hydrocarbons in such environments, it is crucial to study microbial activities, taking into account sediment characteristics, physical-chemical factors (electron acceptors, temperature), nutrients, co-metabolites availability as well as sediment’s reworking due to bioturbation activities. Key information could be collected from in situ studies, which provide an overview of microbial processes, but it is difficult to integrate all parameters involved. Microcosm experiments allow to dissect in-depth some mechanisms involved in hydrocarbon degradation but exclude environmental complexity. To overcome these lacks, strategies have been developed, by creating experiments as close as possible to environmental conditions, for studying natural microbial communities subjected to oil pollution. We present here a review of these approaches, their results and limitation, as well as the promising future of applying “omics” approaches to characterize in-depth microbial communities and metabolic networks involved in hydrocarbon degradation. In addition

  8. Key geochemical factors regulating Mn(IV)-catalyzed anaerobic nitrification in coastal marine sediments

    NASA Astrophysics Data System (ADS)

    Lin, Hui; Taillefert, Martial

    2014-05-01

    The reduction of Mn(IV) oxides coupled to the anaerobic oxidation of NH4+ has been proposed for more than a decade to contribute to the fixed nitrogen pool in marine sediments, yet the existence of this process is still under debate. In this study, surface sediments from an intertidal salt marsh were incubated with MnO2 in the presence of elevated concentrations of NH4+ to test the hypothesis that the reduction of Mn(IV) oxides catalyzes anaerobic NH4+ oxidation to NO2- or NO3-. Geochemical factors such as the ratio of Mn(IV) to NH4+, the type of Mn(IV) oxides (amorphous or colloidal MnO2), and the redox potential of the sediment significantly affect the activity of anaerobic nitrification. Incubations show that the net production of NO3- is stimulated under anaerobic conditions with external addition of colloidal but not amorphous MnO2 and is facilitated by the presence of high concentrations of NH4+. Mass balance calculations demonstrate that anaerobic NH4+ oxidation contributes to the net consumption of NH4+, providing another piece of evidence for the occurrence of Mn(IV)-catalyzed anaerobic nitrification in coastal marine sediments. Finally, anaerobic nitrification is stimulated by the amendment of small concentrations of NO3- or the absence of sulfate reduction, suggesting that moderately reducing conditions favor anaerobic NH4+ oxidation. Overall, these findings suggest that Mn(IV)-catalyzed anaerobic nitrification in suboxic sediments with high N/Mn concentration ratios and highly reactive manganese oxides may be an important source of NO2- and NO3- for subsequent marine nitrogen loss via denitrification or anammox.

  9. Species Richness and Adaptation of Marine Fungi from Deep-Subseafloor Sediments

    PubMed Central

    Rédou, Vanessa; Navarri, Marion; Meslet-Cladière, Laurence; Barbier, Georges

    2015-01-01

    The fungal kingdom is replete with unique adaptive capacities that allow fungi to colonize a wide variety of habitats, ranging from marine habitats to freshwater and terrestrial habitats. The diversity, importance, and ecological roles of marine fungi have recently been highlighted in deep-subsurface sediments using molecular methods. Fungi in the deep-marine subsurface may be specifically adapted to life in the deep biosphere, but this can be demonstrated only using culture-based analyses. In this study, we investigated culturable fungal communities from a record-depth sediment core sampled from the Canterbury Basin (New Zealand) with the aim to reveal endemic or ubiquist adapted isolates playing a significant ecological role(s). About 200 filamentous fungi (68%) and yeasts (32%) were isolated. Fungal isolates were affiliated with the phyla Ascomycota and Basidiomycota, including 21 genera. Screening for genes involved in secondary metabolite synthesis also revealed their bioactive compound synthesis potential. Our results provide evidence that deep-subsurface fungal communities are able to survive, adapt, grow, and interact with other microbial communities and highlight that the deep-sediment habitat is another ecological niche for fungi. PMID:25769836

  10. Gamma-emitting radionuclides in the shallow marine sediments off the Sindh coast, Arabian Sea.

    PubMed

    Akram, M; Qureshi, Riffat M; Ahmad, Nasir; Solaija, Tariq Jamal

    2006-01-01

    Determination of gamma emitting radionuclides in shallow marine sediments off the Sindh coast has been carried out using a gamma spectrometry technique. The activity concentration measured in various sediment samples off the Sindh coast has been found to vary from 15.93 +/- 5.22 to 30.53 +/- 4.70 Bq kg(-1) for 226Ra, from 11.72 +/- 1.22 to 33.94 +/- 1.86 Bq kg(-1) for 228Ra and from 295.22 +/- 32.83 to 748.47 +/- 28.75 Bq kg(-1) for 40K. The calculated mean values of radium equivalent activity, absorbed dose rate and effective dose are 98 Bq kg(-1), 49 nGy h(-1) and 0.06 mSv y(-1), respectively. No artificial radionuclide was detected in the samples measured from the study area. As no data on radioactivity of the coastal environment of Pakistan are available, the data presented here will serve as baseline information on radionuclide concentration in shallow sea sediments off the Sindh coast. The data will also be useful for tracking pollution inventories from unusual radiological events (if any) in the territorial waters of the study area. Further, the information presented will contribute to modelling of a regional radioactivity database from the perspectives of the International Atomic Energy Agency's Asia-Pacific Marine Radioactivity Database and Global Marine Radioactivity Database.

  11. Species richness and adaptation of marine fungi from deep-subseafloor sediments.

    PubMed

    Rédou, Vanessa; Navarri, Marion; Meslet-Cladière, Laurence; Barbier, Georges; Burgaud, Gaëtan

    2015-05-15

    The fungal kingdom is replete with unique adaptive capacities that allow fungi to colonize a wide variety of habitats, ranging from marine habitats to freshwater and terrestrial habitats. The diversity, importance, and ecological roles of marine fungi have recently been highlighted in deep-subsurface sediments using molecular methods. Fungi in the deep-marine subsurface may be specifically adapted to life in the deep biosphere, but this can be demonstrated only using culture-based analyses. In this study, we investigated culturable fungal communities from a record-depth sediment core sampled from the Canterbury Basin (New Zealand) with the aim to reveal endemic or ubiquist adapted isolates playing a significant ecological role(s). About 200 filamentous fungi (68%) and yeasts (32%) were isolated. Fungal isolates were affiliated with the phyla Ascomycota and Basidiomycota, including 21 genera. Screening for genes involved in secondary metabolite synthesis also revealed their bioactive compound synthesis potential. Our results provide evidence that deep-subsurface fungal communities are able to survive, adapt, grow, and interact with other microbial communities and highlight that the deep-sediment habitat is another ecological niche for fungi.

  12. Marine sediment sample preparation for analysis for low concentrations of fine detrital gold

    USGS Publications Warehouse

    Clifton, H. Edward; Hubert, Arthur; Phillips, R. Lawrence

    1967-01-01

    Analyses by atomic absorption for detrital gold in more than 2,000 beach, offshore, marine-terrace, and alluvial sands from southern Oregon have shown that the values determined from raw or unconcentrated sediment containing small amounts of gold are neither reproducible nor representative of the initial sample. This difficulty results from a 'particle sparsity effect', whereby the analysis for gold in a given sample depends more upon the occurrence of random flakes of gold in the analyzed portion than upon the actual gold content of the sample. The particle sparsity effect can largely be eliminated by preparing a gold concentrate prior to analysis. A combination of sieve, gravimetric, and magnetic separation produces a satisfactory concentrate that yields accurate and reproducible analyses. In concentrates of nearly every marine and beach sand studied, the gold occurs in the nonmagnetic fraction smaller than 0.124 mm and with a specific gravity greater than 3.3. The grain size of gold in stream sediments is somewhat more variable. Analysis of concentrates provides a means of greatly increasing the sensitivity of the analytical technique in relation to the initial sample. Gold rarely exceeds 1 part per million in even the richest black sand analyzed; to establish the distribution of gold (and platinum) in marine sediments and its relationship to source and environmental factors, one commonly needs to know their content to the part per billion range. Analysis of a concentrate and recalculation to the value in the initial sample permits this degree of sensitivity.

  13. Polycyclic aromatic hydrocarbons in surface sediments and marine organisms from the Daya Bay, South China.

    PubMed

    Sun, Run-Xia; Lin, Qin; Ke, Chang-Liang; Du, Fei-Yan; Gu, Yang-Guang; Cao, Kun; Luo, Xiao-Jun; Mai, Bi-Xian

    2016-02-15

    Polycyclic aromatic hydrocarbons (PAHs) were investigated in the marine ecosystem of the Daya Bay, South China. The PAH concentrations ranged from 340 to 710 ng/g dry weight in the sediments and from 110 to 520 ng/g wet weight in marine organisms, respectively. The dominant compounds were three- and four-ring PAHs in the sediments (53%-89%) and two- and three-ring PAHs in the marine species (67%-94%), respectively. PAHs mainly originated from both pyrolytic and petrogenic sources. Comparison with the effects-based sediment quality guideline values suggested that the ecological risk caused by the total PAHs was relatively low (less than 25% incidence of adverse effects) in the sedimentary environment. The median cancer risk level via seafood consumption (1.6 × 10(-5) for urban residents and 1.2 × 10(-5) for rural residents, respectively) was slightly higher than the maximum admissible level (10(-5)) set by US EPA, but lower than the priority risk level (10(-4)).

  14. [Experimental study of vibrio parahaemolyticus (biotype 2) transfer from water and sediments to benthic marine food chain organisms].

    PubMed

    Gauthier, M J; Clement, R

    1979-04-01

    Transfer of Vibrio parahaemolyticus (biotype 2) from sediments to water and from water to benthic marine organisms was studied experimentally using a streptomycin-resistant strain. Transmission by trophic pathways was also studied using reconstituted marine food chains (Mytilus edulis, Nereis diversicolor, Carcinus maenas, Scorpaena porcus, Mus musculus). Water colonization by sediments could be observed only at temperatures above 16 degrees C. Sediments could well constitute a disseminating reservoir for these germs, their cycle in water being dependent of the cycle followed in the sediments. Contamination of animal organisms is essentially effected by a direct mean, either water or sediments; transfer by trophic pathways being negligible. Infection of land consumers (mice) is linked quantitatively to the nature of the last marine organism of the food chain since bacteria can flourish in the digestive tract of certain animals (Carcinus maenas). PMID:487292

  15. Watershed-Marine Linkages: Monitoring how Terrigenous Runoff and Wave-Induced Resuspension Affect Marine Sediment Dynamics in Bays with Coral Reefs, St. John, USVI

    NASA Astrophysics Data System (ADS)

    Campbell, S.; Gray, S. C.; Whinney, J.; Ramos-Scharron, C. E.; Campbell, S.; LaFevor, M. C.

    2015-12-01

    In the USVI, land-based sedimentation in coastal marine environments has increased due to watershed development and is a major cause of coral reef degradation. Watershed runoff and wave/current-induced resuspension of benthic sediment contribute to turbidity/sedimentation. Our objectives are to characterize the spatial and temporal variability of marine sediment dynamics in response to runoff and resuspension in shoreline and reef areas of St. John, USVI, and directly compare the efficacy of time-integrated vs. high-resolution sediment monitoring approaches. To complement a six-year sediment trap study of sedimentation, nephelometers (10-min resolution) were deployed alongside sediment traps (26 day resolution) at four ephemeral stream outfalls and three reefs sites below comparable developed and minimally developed catchments. Watershed runoff was monitored using stream (10-min resolution) and peak crest (2-week resolution) gauges. Mean turbidity/deposition were 4/5 times greater at shore compared to reef sites, 5/6 times greater below developed compared to minimally developed catchments, 2/4 times greater during runoff compared to non-runoff periods, and 100/500 times background levels (time series median) following the largest runoff event of the 5-month time series. Turbidity values due to resuspension during non-runoff periods were primarily controlled by wave height (71% of the variability), tides, and the presence of finer sediment grains. However, the relative contribution to total sedimentation of resuspension vs. watershed runoff varied spatially between sites due to variations in bay geography, benthic sediment grain size, and catchment characteristics. Sediment traps and nephelometers recorded generally consistent temporal patterns of sedimentation at most sites. Though our study confirmed that watershed development increases turbidity and deposition in bays with coral reefs, multiple processes govern sediment dynamics and the distribution of sediments

  16. The link between marine sediment records and changes in Holocene Saharan landscape: simulating the dust cycle

    NASA Astrophysics Data System (ADS)

    Egerer, Sabine; Claussen, Martin; Reick, Christian; Stanelle, Tanja

    2016-04-01

    Marine sediment records reveal an abrupt and strong increase in dust deposition in the North Atlantic at the end of the African Humid Period about 4.9 to 5.5 ka ago. The change in dust flux has been attributed to varying Saharan land surface cover. Alternatively, the enhanced dust accumulation is linked to enhanced surface winds and a consequent intensification of coastal upwelling. Here we demonstrate for the first time the direct link between dust accumulation in marine cores and changes in Saharan land surface. We simulate the mid-Holocene (6 ka BP) and pre-industrial (1850 AD) dust cycle as a function of Saharan land surface cover and atmosphere-ocean conditions using the coupled atmosphere-aerosol model ECHAM6.1-HAM2.1. Mid-Holocene surface characteristics, including vegetation cover and lake surface area, are derived from proxy data and simulations. In agreement with data from marine sediment cores, our simulations show that mid-Holocene dust deposition fluxes in the North Atlantic were two to three times lower compared with pre-industrial fluxes. We identify Saharan land surface characteristics to be the main control on dust transport from North Africa to the North Atlantic. We conclude that the increase in dust accumulation in marine cores is directly linked to a transition of the Saharan landscape during the Holocene and not due to changes in atmospheric or ocean conditions alone.

  17. (129)I record of nuclear activities in marine sediment core from Jiaozhou Bay in China.

    PubMed

    Fan, Yukun; Hou, Xiaolin; Zhou, Weijian; Liu, Guangshan

    2016-04-01

    Iodine-129 has been used as a powerful tool for environmental tracing of human nuclear activities. In this work, a sediment core collected from Jiaozhou Bay, the east coast of China, in 2002 was analyzed for (129)I to investigate the influence of human nuclear activities in this region. Significantly enhanced (129)I level was observed in upper 70 cm of the sediment core, with peak values in the layer corresponding to 1957, 1964, 1974, 1986, and after 1990. The sources of (129)I and corresponding transport processes in this region are discussed, including nuclear weapons testing at the Pacific Proving Grounds, global fallout from a large numbers of nuclear weapon tests in 1963, the climax of Chinese nuclear weapons testing in the early 1970s, the Chernobyl accident in 1986, and long-distance dispersion of European reprocessing derived (129)I. The very well (129)I records of different human nuclear activities in the sediment core illustrate the potential application of (129)I in constraining ages and sedimentation rates of the recent sediment. The releases of (129)I from the European nuclear fuel reprocessing plants at La Hague (France) and Sellafield (UK) were found to dominate the inventory of (129)I in the Chinese sediments after 1990, not only the directly atmospheric releases of these reprocessing plants, but also re-emission of marine discharged (129)I of these reprocessing plants in the highly contaminated European seas. PMID:26821329

  18. Seasonal and spatial diversity of microbial communities in marine sediments of the South China Sea.

    PubMed

    Du, Jikun; Xiao, Kai; Huang, Yali; Li, Huixian; Tan, Hongming; Cao, Lixiang; Lu, Yongjun; Zhou, Shining

    2011-10-01

    This study was conducted to characterize the diversity of microbial communities in marine sediments of the South China Sea by means of 16S rRNA gene clone libraries. The results revealed that the sediment samples collected in summer harboured a more diverse microbial community than that collected in winter, Deltaproteobacteria dominated 16S rRNA gene clone libraries from both seasons, followed by Gammaproteobacteria, Acidobacteria, Nitrospirae, Planctomycetes, Firmicutes. Archaea phylotypes were also found. The majority of clone sequences shared greatest similarity to uncultured organisms, mainly from hydrothermal sediments and cold seep sediments. In addition, the sedimentary microbial communities in the coastal sea appears to be much more diverse than that of the open sea. A spatial pattern in the sediment samples was observed that the sediment samples collected from the coastal sea and the open sea clustered separately, a novel microbial community dominated the open sea. The data indicate that changes in environmental conditions are accompanied by significant variations in diversity of microbial communities at the South China Sea.

  19. (129)I record of nuclear activities in marine sediment core from Jiaozhou Bay in China.

    PubMed

    Fan, Yukun; Hou, Xiaolin; Zhou, Weijian; Liu, Guangshan

    2016-04-01

    Iodine-129 has been used as a powerful tool for environmental tracing of human nuclear activities. In this work, a sediment core collected from Jiaozhou Bay, the east coast of China, in 2002 was analyzed for (129)I to investigate the influence of human nuclear activities in this region. Significantly enhanced (129)I level was observed in upper 70 cm of the sediment core, with peak values in the layer corresponding to 1957, 1964, 1974, 1986, and after 1990. The sources of (129)I and corresponding transport processes in this region are discussed, including nuclear weapons testing at the Pacific Proving Grounds, global fallout from a large numbers of nuclear weapon tests in 1963, the climax of Chinese nuclear weapons testing in the early 1970s, the Chernobyl accident in 1986, and long-distance dispersion of European reprocessing derived (129)I. The very well (129)I records of different human nuclear activities in the sediment core illustrate the potential application of (129)I in constraining ages and sedimentation rates of the recent sediment. The releases of (129)I from the European nuclear fuel reprocessing plants at La Hague (France) and Sellafield (UK) were found to dominate the inventory of (129)I in the Chinese sediments after 1990, not only the directly atmospheric releases of these reprocessing plants, but also re-emission of marine discharged (129)I of these reprocessing plants in the highly contaminated European seas.

  20. Winogradskyella sediminis sp. nov., isolated from marine sediment.

    PubMed

    Zhang, De-Chao; Liu, Yan-Xia; Huang, Hai-Jun; Weber, Karin; Margesin, Rosa

    2016-08-01

    A Gram-stain-negative, rod-shaped, yellow-pigmented, gliding bacterial strain, designated S5-23-3T, was isolated from a sediment sample of the Yellow Sea in China. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain S5-23-3T was related to the genus Winogradskyella and had highest 16S rRNA gene sequence similarities with Winogradskyella arenosi JCM 15527T (97.6 %), Winogradskyella rapida CECT 7392T (97.4 %) and Winogradskyella undariae KCTC 32261T (97.2 %). The predominant cellular fatty acids were iso-C15 : 0, iso-C15 : 1 G, iso-C15 : 0 3-OH and iso-C17 : 0 3-OH. Strain S5-23-3T contained MK-6 as the predominant menaquinone. The polar lipid profile contained phosphatidylethanolamine, two aminolipids, one aminoglycolipid, one aminophospholipid, one unidentified phospholipid and seven unidentified polar lipids. The genomic DNA G+C content of strain S5-23-3T was 36.1 mol%. Combined data from phenotypic, chemotaxonomic, phylogenetic and DNA-DNA relatedness studies demonstrated that strain S5-23-3T is a representative of a novel species of the genus Winogradskyella, for which the name Winogradskyellasediminis sp. nov. (type strain S5-23-3T=LMG 28075T=DSM 28134T) is proposed. PMID:27189204

  1. Leisingera nanhaiensis sp. nov., isolated from marine sediment.

    PubMed

    Sun, Fengqin; Wang, Baojiang; Liu, Xiupian; Lai, Qiliang; Du, Yaping; Li, Guangyu; Luo, Jie; Shao, Zongze

    2010-02-01

    An aerobic, Gram-staining-negative, motile, rod-shaped bacterium, strain NH52F(T), was isolated from a sandy sediment sample taken from the South China Sea. On M2 agar medium (a complex medium), colonies were beige in colour. The isolate showed highest 16S rRNA gene sequence similarities to members of the genera Leisingera (96.7 % similarity), Phaeobacter (95.4-96.0 %) and Marinovum (94.1 %). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NH52F(T) formed a distinct cluster with Leisingera methylohalidivorans MB2(T) and Leisingera aquimarina LMG 24366(T). Optimal growth was observed at pH 7.0-8.5 and 25 degrees C and the new isolate required the presence of 1-4 % (w/v) NaCl. The major fatty acids were C(18 : 1)omega7c, C(16 : 0) 2-OH, C(10 : 0) 3-OH, C(12 : 0) 3-OH, C(16 : 0) and 11-methyl C(18 : 1)omega7c. The DNA G+C content was 60.5 mol%. The phylogenetic and chemotaxonomic characteristics of strain NH52F(T) were similar to those of the genus Leisingera. However, the differences in phenotypic properties and the 16S rRNA gene similarity values demonstrated that the new isolate differed from recognized species of the genus Leisingera. On the basis of phenotypic, chemotaxonomic and phylogenetic data, this organism should be classified as a representative of a novel species in the genus Leisingera, for which the name Leisingera nanhaiensis sp. nov. is proposed. The type strain is NH52F(T) (=LMG 24841(T)=CCTCC AB 208316(T)=MCCC 1A04178(T)).

  2. Rhodococcus nanhaiensis sp. nov., an actinobacterium isolated from marine sediment.

    PubMed

    Li, Jie; Zhao, Guo-Zhen; Long, Li-Juan; Wang, Fa-Zuo; Tian, Xin-Peng; Zhang, Si; Li, Wen-Jun

    2012-10-01

    In this study, two strains (SCSIO 10187(T) and SCSIO 10197) were isolated from a sediment sample collected from the South China Sea and characterized by using a polyphasic approach. Growth was observed at 15-35 °C (optimum 28 °C) and pH 5.0-8.0 (optimum pH 6.0). Based on 16S rRNA gene sequence analysis, the strains were identified as members of the genus Rhodococcus. Phylogenetic analysis showed that the two strains clustered together and the 16S rRNA gene sequence similarities between them and other members of the genus Rhodococcus were 93.2-97.7 %. The menaquinone type was MK-8(H(2)). Major cellular fatty acids were C(16 : 0), C(18 : 1)ω9c, C(17 : 0), 10-methyl C(18 : 0), C(18 : 0), C(19 : 0) and C(17 : 1)ω8c. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannoside. The DNA G+C contents of strains SCSIO 10187(T) and SCSIO 10197 were 63.7 and 63.2 mol%, respectively. The combined genotypic and phenotypic data showed that the two strains represent a novel species of the genus Rhodococcus, for which the name Rhodococcus nanhaiensis is proposed; the type strain is SCSIO 10187(T) ( = DSM 45608(T) = CCTCC AB 2011024(T)), with SCSIO 10197 ( = DSM 45609 = CCTCC AB 2011025) as a reference strain.

  3. Sorption and competition of two persistent organic pesticides onto marine sediments: Relevance to their distribution in aquatic system.

    PubMed

    Soubaneh, Youssouf Djibril; Gagné, Jean-Pierre; Lebeuf, Michel; Nikiforov, Vladimir; Gouteux, Bruno; Osman, Awaleh Mohamed

    2015-07-01

    Sorption is a key process in the distribution of substances between environmental compartments in marine ecosystems. Two persistent organic pesticides, also known as toxaphene congeners, namely B8-1413 (P26) and B9-1679 (P50), are of special interest because they are not detected in sediments while relatively concentrated in marine mammals. Sorption-desorption, entrapment and competition behaviors of these pesticides onto marine sediments were studied to explain their environmental distribution. Data obtained under marine experimental conditions were fitted to sorption models to evaluate sorption coefficients and to assess the degree of B8-1413/B9-1679 entrapment of the two toxaphene congeners in sediments. Carbon normalized sorption coefficients (Koc) of both congeners were similar under in cold (2°C) marine (30 psu) conditions with high values ranging from 1.53×10(5) to 3.28×10(5) mL g(-1)indicative of a strong affinity to marine sediments However, the sorption-desorption investigations indicate that B8-1413/B9-1679 were on average 2.5 times less entrapped in sediments compared to B7-1450, a toxaphene congener known to accumulate predominantly in sediments. These results suggest that the low entrapment of B8-1413 and B9-1679 favor their availability and transfer to biological matrices.

  4. Sorption and competition of two persistent organic pesticides onto marine sediments: Relevance to their distribution in aquatic system.

    PubMed

    Soubaneh, Youssouf Djibril; Gagné, Jean-Pierre; Lebeuf, Michel; Nikiforov, Vladimir; Gouteux, Bruno; Osman, Awaleh Mohamed

    2015-07-01

    Sorption is a key process in the distribution of substances between environmental compartments in marine ecosystems. Two persistent organic pesticides, also known as toxaphene congeners, namely B8-1413 (P26) and B9-1679 (P50), are of special interest because they are not detected in sediments while relatively concentrated in marine mammals. Sorption-desorption, entrapment and competition behaviors of these pesticides onto marine sediments were studied to explain their environmental distribution. Data obtained under marine experimental conditions were fitted to sorption models to evaluate sorption coefficients and to assess the degree of B8-1413/B9-1679 entrapment of the two toxaphene congeners in sediments. Carbon normalized sorption coefficients (Koc) of both congeners were similar under in cold (2°C) marine (30 psu) conditions with high values ranging from 1.53×10(5) to 3.28×10(5) mL g(-1)indicative of a strong affinity to marine sediments However, the sorption-desorption investigations indicate that B8-1413/B9-1679 were on average 2.5 times less entrapped in sediments compared to B7-1450, a toxaphene congener known to accumulate predominantly in sediments. These results suggest that the low entrapment of B8-1413 and B9-1679 favor their availability and transfer to biological matrices. PMID:25765263

  5. Physicochemical and geochemical characteristics of raw marine sediment used in fluoride removal.

    PubMed

    El-Said, Ghada F; Draz, Suzanne E O

    2010-10-01

    The study was directed to use raw marine sediment in the removal of fluoride. The sediment was mainly composed of calcite, magnesium-calcite and aragonite. The effect of the initial fluoride concentration, pH and the contact time was studied at room temperature to determine the adsorption capacity of the sediment. The optimum adsorption capacity was observed at pH values of 5 and 6.2. The adsorption process was fast and the equilibrium was reached within 60 min. For fluoride solutions of 10 and 15 mg/L, 100% removal was obtained onto 0.1 g of raw marine sediment. Pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion equations were used to deduce the kinetic data. The adsorption mechanism was rather complex process, and the intra-particle diffusion was not the only rate-controlling step. The equilibrium data were tested using thirteen isotherm models (Langmuir, Freundlich, Tempkin, Dubinin-Radushkevich, Erunauer-Emmett-Teller, Flory-Huggins, Non-ideal competitive adsorption, Generalized, Redlich Peterson, Khan, Sips, Koble Corrigan and Toth isotherm equations). Five different error functions were applied. For the sorption of fluoride process, the calculated activation energy and the free energy were of 0.707 and -14.491 kJ /mol, respectively. PMID:20721801

  6. Anaerobic degradation of alcohol ethoxylates and polyethylene glycols in marine sediments.

    PubMed

    Traverso-Soto, Juan M; Rojas-Ojeda, Patricia; Sanz, José Luis; González-Mazo, Eduardo; Lara-Martín, Pablo A

    2016-02-15

    This research is focused on alcohol polyethoxylates (AEOs), nonionic surfactants used in a wide variety of products such as household cleaners and detergents. Our main objective in this work was to study the anaerobic degradation of these compounds and their main aerobic degradation products and precursors (polyethylene glycols, PEGs, which are also used for many other applications) in marine sediments, providing the first data available on this topic. First, we observed that average AEO sediment-water partition coefficients (Kd) increased towards those homologs having longer alkyl chains (from 257 L/kg for C12 to 5772 L/kg for C18),which were less susceptible to undergo biodegradation. Overall, AEO and PEG removal percentages reached up to 99.7 and 93%, respectively, after 169 days of incubation using anaerobic conditions in sediments ([O2] = 0 ppm, Eh = -170 to -380 mV and T = 30 °C). Average half-life was estimated to be in a range from 10 to 15 days for AEO homologs (C12AEO8-C18AEO8), and 18 days for PEGEO8.Methanogenic activity proved to be intense during the experiment, confirming the occurrence of anaerobic conditions. This is the first study showing that AEOs and PEGs can be degraded in absence of oxygen in marine sediments, so this new information should be taken into account for future environmental risk assessments on these chemicals. PMID:26657255

  7. Tetrahymanol, the most likely precursor of gammacerane, occurs ubiquitously in marine sediments

    NASA Astrophysics Data System (ADS)

    ten Haven, H. L.; Rohmer, M.; Rullkötter, J.; Bisseret, P.

    1989-11-01

    Tetrahymanol has been identified in several sediment samples from different depositional environments by gas chromatography-mass spectrometry and by coinjections with an authentic standard. Together with literature data this shows that tetrahymanol is likely to be widespread, which is in accordance with the ubiquitous occurrence of its presumed diagenetic product, gammacerane, in more mature sediments and crude oils. The diagenetic conversion of tetrahymanol to gammacerane most likely proceeds via dehydration and subsequent hydrogenation. The intermediate in this conversion, gammacer-2-ene, has been synthesized, and its presence in one sample confirmed by coinjections. The identification of tetrahymanol in marine sediments indicates either that protozoa of the genus Tetrahymena are widely distributed or that tetrahymanol is also a natural product of organisms other than Tetrahymena.

  8. Sediment characteristics and benthic ecological status in contrasting marine environments of subtropical Hong Kong.

    PubMed

    Chan, Alice K Y; Xu, Wen-Zhe; Liu, Xiao-Shou; Cheung, Siu Gin; Shin, Paul K S

    2016-02-15

    Sediment characteristics and benthic communities on a finer sampling scale in four contrasting environments in subtropical Hong Kong were analyzed in summer and winter 2012. In two harbour habitats which suffered from historic sewage pollution or hypoxic events, organic carbon, nutrient and trace metal content in the sediment were significantly higher than that in an offshore area and a marine reserve. The relatively low organic and nutrient content in the offshore habitat could be resulted from enhanced resuspension of such materials from the seabed owing to intense water mixing and disturbance caused by bottom trawling. The biotic indices AMBI and M-AMBI were shown to be useful in assessing the benthic ecological status of these habitats. Such indices can also be more sensitive than sediment physico-chemical parameters in differentiating the response of macrofauna to seasonal changes in the benthic environment.

  9. The effect of temperature on organic carbon degradation in marine sediments

    PubMed Central

    Malinverno, Alberto; Martinez, Ernesto A.

    2015-01-01

    The degradation of sedimentary particulate organic carbon (POC) is a key carbon cycle process that fuels the deep subseafloor biosphere. The reactivity of POC is expected to decrease with increasing sediment age, severely restricting the energy available to microorganisms. Conversely, increasing temperatures during burial have been proposed to stimulate POC degradation, possibly supplying significant energy to the deep biosphere. To test the importance of temperature, we assembled POC measurements in two global sets of drill sites where sediments underwent either relatively low or high temperatures during burial, which should have resulted in different rates of POC degradation. For ages 5–10 Ma, the decrease of the average POC content with burial is clearly more pronounced in the sites with high temperature histories. Our results support the hypothesis that temperature is one of the fundamental controls on the rate of POC degradation within deeply buried marine sediments. PMID:26640172

  10. Persistence and Stability of Teflubenzuron and Diflubenzuron When Associated to Organic Particles in Marine Sediment.

    PubMed

    Samuelsen, Ole B

    2016-02-01

    The persistence and stability of the oral administered anti salmon-lice drugs teflubenzuron and diflubenzuron were tested when associated to organic material as faecal particles from Atlantic salmon and medicated food pellets. This laboratory study was performed in seawater under aerobic conditions, at 7°C in the dark and showed that both compounds were remarkably persistent and stable since no significant reduction in the concentrations of flubenzurons in sediment were seen after 24 weeks. Therefore neither chemical or microbial degradation nor outwashing seems to be important pathways for these drugs to disappear from sediment under fish farms. Thus, it is more likely that the decrease of flubenzurons from marine sediments described in field investigations is caused by either bioturbation, resuspension of organic particles or a combination of these.

  11. Molecular tools to understand the bioremediation effect of plants and earthworms on contaminated marine sediments.

    PubMed

    Moreno, Beatriz; Cañizares, Rosa; Macci, Cristina; Doni, Serena; Masciandaro, Grazia; Benitez, Emilio

    2015-12-30

    A meso-scale pilot plant was set up to test the efficiency of a bioremediation scheme applied to marine sediments contaminated by heavy metals and hydrocarbons. The experiment was implemented for three years in two stages using two remediation agents: plants (Paspalum vaginatum and Tamarix gallica) and earthworms (Eisenia fetida). DNA and RNA-based methodologies were applied to elucidate the dynamics of the bacterial population and were related to improving biological and chemical conditions of the sediments. Bioremediation strategies were successful in removing pollutants from the contaminated sediments and specialization within the bacterial community related to the type of contamination present was detected in the different stages of the process. The highest response of Gram-positive PAH-degraders to the contamination was detected at the beginning and after the first stage of the experiment, corresponding to the uppermost values of degradation.

  12. Nucleation and growth of todorokite from birnessite: Implications for trace-metal cycling in marine sediments

    NASA Astrophysics Data System (ADS)

    Atkins, Amy L.; Shaw, Samuel; Peacock, Caroline L.

    2014-11-01

    The phyllomanganate birnessite is the main Mn-bearing phase in oxic marine sediments, and through coupled sorption and redox exerts a strong control on the oceanic concentration of micronutrient trace metals. However, under diagenesis and mild hydrothermal conditions, birnessite undergoes transformation to the tectomanganate todorokite. The mechanistic details of this transformation are important for the speciation and mobility of metals sequestered by birnessite, and are necessary in order to quantify the role of marine sediments in global trace element cycles. Here we transform a synthetic, poorly crystalline, hexagonal birnessite, analogous to marine birnessite, into todorokite under a mild reflux procedure, developed to mimic marine diagenesis and mild hydrothermal conditions. We characterize our birnessite and reflux products as a time series, employing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), BET surface area analysis, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM) and extended X-ray absorption fine structure spectroscopy (EXAFS). We provide new insight into the crystallization pathway and mechanism of todorokite formation from birnessite under conditions analogous to those found in marine diagenetic and hydrothermal settings. Specifically we propose a new four-stage process for the transformation of birnessite to todorokite, beginning with todorokite nucleation, then crystal growth from solution to form todorokite primary particles, followed by their self-assembly and oriented growth via oriented attachment to form crystalline todorokite laths, culminating in traditional crystal ripening. We suggest that, contrary to current understanding, trace metals like Ni might retard the transformation of birnessite to todorokite and be released to marine sedimentary pore-waters during this diagenetic process, thus potentially providing a benthic flux of these micronutrients to seawater.

  13. Phylogenetic Characterization of Marine Benthic Archaea in Organic-Poor Sediments of the Eastern Equatorial Pacific Ocean (ODP Site 1225)

    PubMed Central

    Lauer, Antje; Sørensen, Ketil Bernt; Teske, Andreas

    2016-01-01

    Sequencing surveys of microbial communities in marine subsurface sediments have focused on organic-rich, continental margins; the database for organic-lean deep-sea sediments from mid-ocean regions is underdeveloped. The archaeal community in subsurface sediments of ODP Site 1225 in the eastern equatorial Pacific (3760 m water depth; 1.1 and 7.8 m sediment depth) was analyzed by PCR, cloning and sequencing, and by denaturant gradient gel electrophoresis (DGGE) of 16S rRNA genes. Three uncultured archaeal lineages with different depth distributions were found: Marine Group I (MG-I) within the Thaumarchaeota, its sister lineage Marine Benthic Group A (MBG-A), the phylum-level archaeal lineage Marine Benthic Group B (also known as Deep-Sea Archaeal Group or Lokiarchaeota), and the Deep-Sea Euryarchaeotal Group 3. The MG-I phylotypes included representatives of sediment clusters that are distinct from the pelagic members of this phylum. On the scale from fully oxidized, extremely organic carbon-depleted sediments (for example, those the South Pacific Gyre) to fully reduced, organic carbon-rich marine subsurface sediments (such as those of the Peru Margin), Ocean Drilling Program (ODP) Site 1225 falls into the non-extreme organic carbon-lean category, and harbors archaeal communities from both ends of the spectrum.

  14. Phylogenetic Characterization of Marine Benthic Archaea in Organic-Poor Sediments of the Eastern Equatorial Pacific Ocean (ODP Site 1225)

    PubMed Central

    Lauer, Antje; Sørensen, Ketil Bernt; Teske, Andreas

    2016-01-01

    Sequencing surveys of microbial communities in marine subsurface sediments have focused on organic-rich, continental margins; the database for organic-lean deep-sea sediments from mid-ocean regions is underdeveloped. The archaeal community in subsurface sediments of ODP Site 1225 in the eastern equatorial Pacific (3760 m water depth; 1.1 and 7.8 m sediment depth) was analyzed by PCR, cloning and sequencing, and by denaturant gradient gel electrophoresis (DGGE) of 16S rRNA genes. Three uncultured archaeal lineages with different depth distributions were found: Marine Group I (MG-I) within the Thaumarchaeota, its sister lineage Marine Benthic Group A (MBG-A), the phylum-level archaeal lineage Marine Benthic Group B (also known as Deep-Sea Archaeal Group or Lokiarchaeota), and the Deep-Sea Euryarchaeotal Group 3. The MG-I phylotypes included representatives of sediment clusters that are distinct from the pelagic members of this phylum. On the scale from fully oxidized, extremely organic carbon-depleted sediments (for example, those the South Pacific Gyre) to fully reduced, organic carbon-rich marine subsurface sediments (such as those of the Peru Margin), Ocean Drilling Program (ODP) Site 1225 falls into the non-extreme organic carbon-lean category, and harbors archaeal communities from both ends of the spectrum. PMID:27681926

  15. Phylogenetic Characterization of Marine Benthic Archaea in Organic-Poor Sediments of the Eastern Equatorial Pacific Ocean (ODP Site 1225).

    PubMed

    Lauer, Antje; Sørensen, Ketil Bernt; Teske, Andreas

    2016-01-01

    Sequencing surveys of microbial communities in marine subsurface sediments have focused on organic-rich, continental margins; the database for organic-lean deep-sea sediments from mid-ocean regions is underdeveloped. The archaeal community in subsurface sediments of ODP Site 1225 in the eastern equatorial Pacific (3760 m water depth; 1.1 and 7.8 m sediment depth) was analyzed by PCR, cloning and sequencing, and by denaturant gradient gel electrophoresis (DGGE) of 16S rRNA genes. Three uncultured archaeal lineages with different depth distributions were found: Marine Group I (MG-I) within the Thaumarchaeota, its sister lineage Marine Benthic Group A (MBG-A), the phylum-level archaeal lineage Marine Benthic Group B (also known as Deep-Sea Archaeal Group or Lokiarchaeota), and the Deep-Sea Euryarchaeotal Group 3. The MG-I phylotypes included representatives of sediment clusters that are distinct from the pelagic members of this phylum. On the scale from fully oxidized, extremely organic carbon-depleted sediments (for example, those the South Pacific Gyre) to fully reduced, organic carbon-rich marine subsurface sediments (such as those of the Peru Margin), Ocean Drilling Program (ODP) Site 1225 falls into the non-extreme organic carbon-lean category, and harbors archaeal communities from both ends of the spectrum. PMID:27681926

  16. Phylogenetic Characterization of Marine Benthic Archaea in Organic-Poor Sediments of the Eastern Equatorial Pacific Ocean (ODP Site 1225).

    PubMed

    Lauer, Antje; Sørensen, Ketil Bernt; Teske, Andreas

    2016-09-06

    Sequencing surveys of microbial communities in marine subsurface sediments have focused on organic-rich, continental margins; the database for organic-lean deep-sea sediments from mid-ocean regions is underdeveloped. The archaeal community in subsurface sediments of ODP Site 1225 in the eastern equatorial Pacific (3760 m water depth; 1.1 and 7.8 m sediment depth) was analyzed by PCR, cloning and sequencing, and by denaturant gradient gel electrophoresis (DGGE) of 16S rRNA genes. Three uncultured archaeal lineages with different depth distributions were found: Marine Group I (MG-I) within the Thaumarchaeota, its sister lineage Marine Benthic Group A (MBG-A), the phylum-level archaeal lineage Marine Benthic Group B (also known as Deep-Sea Archaeal Group or Lokiarchaeota), and the Deep-Sea Euryarchaeotal Group 3. The MG-I phylotypes included representatives of sediment clusters that are distinct from the pelagic members of this phylum. On the scale from fully oxidized, extremely organic carbon-depleted sediments (for example, those the South Pacific Gyre) to fully reduced, organic carbon-rich marine subsurface sediments (such as those of the Peru Margin), Ocean Drilling Program (ODP) Site 1225 falls into the non-extreme organic carbon-lean category, and harbors archaeal communities from both ends of the spectrum.

  17. Geomorphological feedback between watershed erosion and marine sedimentation in the Gulf of Lion margin (SE France).

    NASA Astrophysics Data System (ADS)

    Molliex, S.; Rabineau, M.; Leroux, E.; Aslanian, D.; Chauvet, F.; Bourlès, D.; Révillon, S.; Jouët, G.

    2012-04-01

    Margins are the place of transfer, deposit and accumulation of sediment whose geometry is controlled by sea level fluctuation, subsidence and sedimentary fluxes. Surface processes (sedimentation, erosion), vertical movements and deep dynamic are also intimacy linked. Due to the numerous data acquired over the last 10 years, the Gulf of Lion can be considered as a privileged area to understand the feedback between erosion, sedimentation and associated vertical displacements. We tried to improve the understanding of the temporal and spatial evolution of erosion processes in the sedimentation and therefore in the geodynamic evolution of the Gulf of Lion margin during the Quaternary, using available offshore data and comparing them with data from the continental domain. A compilation of offshore seismic profiles allowed us to determine the spatial and temporal evolution of the sedimentary volumes through the Quaternary. In the continental domain, the quantification of eroded volumes allowed us to estimate the respective part of each structural domain within the sedimentation of the Gulf of Lion. Marine and continental data are consistent and show a strong increase of erosion rates since 900 ka, resulting from global climatic changes. 75% of the quaternary sedimentation come from the alpine domain, where erosion rates are 2 or 3 times higher than other orogenic domains as the Pyrenees or the Massif Central mountain belts. A quantitative geomorphology analysis suggests that erosion processes are more consistent with climatic than tectonic parameters. The relationship between marine subsidence and continental uplift is also studied. Vertical displacements of the margin are mainly controlled by isostasic processes, at least during the last 900 ka.

  18. Assessment of radionuclides and heavy metals in marine sediments along the Upper Gulf of Thailand

    NASA Astrophysics Data System (ADS)

    Khuntong, S.; Phaophang, C.; Sudprasert, W.

    2015-05-01

    Due to the Fukushima Daiichi nuclear disaster in 2011 and the development of nuclear power plant in neighboring countries such as Vietnam in the near future, radionuclide assessment in marine sediment during 2010 - 2011 may be useful as background levels for radiation protection in Thailand. Marine sediments (10 samples) were collected approximately 1 km away from the coastline along Chonburi to Pattaya, Chonburi Province. The sediments were ground and sieved through 2-mm test sieve after air drying. Radionuclides were measured with a gamma spectrometer equipped with a well-calibrated HPGe detector. The samples were prepared in the same geometry as the reference material. The optimal counting time was 60,000 - 80,000 s for statistical evaluation and uncertainties. No contamination of 137Cs as an artificial radionuclide was found. Naturally-occurring radionuclides including 238U, 232Th and 40K were found. The mean specific activities of 238U, 232Th and 40K were 44 ± 10, 59 ± 17 and 463 ± 94 Bq/kg in the rainy season (2010); 41 ± 6, 50 ± 9 and 484 ± 83 Bq/kg in the winter (2010), and 39 ± 6, 41 ± 7 and 472 ± 81 Bq/kg in the summer (2011), respectively. The mean specific activities were higher than the values in the UNSCEAR report of 35, 30 and 400 Bq/kg for 238U, 232Th and 40K, respectively. From the measured specific activities, the absorbed dose rate, radium equivalent activity, external hazard index and annual external effective dose rate were calculated in order to assess the health risk. No radiation hazards related to the radioactivity in the sediment were expected. The accumulation of radionuclides varied with the particle size and the organic matter content in the sediment. The accumulation of heavy metals showed similar results to that of the radionuclides in the sediment.

  19. Metals and other elements in tissues of wild fish from fish farms and comparison with farmed species in sites with oxic and anoxic sediments.

    PubMed

    Kalantzi, Ioanna; Black, Kenneth D; Pergantis, Spiros A; Shimmield, Tracy M; Papageorgiou, Nafsika; Sevastou, Katerina; Karakassis, Ioannis

    2013-11-15

    Farmed fish and wild fish aggregating in the vicinity of four Mediterranean fish farms with different environmental conditions were sampled. Levels of metals (including As and Se) were measured in the muscle, liver, gills, bone and intestine. The wild fish from sites with anoxic substrata accumulate metals (including As and Se) from the ambient habitat in their gills whereas those from sites with oxic substrata concentrate these elements through their diet in their intestine. Tissues of wild fish aggregating around farm cages accumulate a greater number of these elements and with higher concentrations than farmed fish. Habitat, diet, ecological needs, fat content of fish, and protein expression may play an important role in these element differences between fish species. Fe in flathead grey mullet, As in surmullet, rainbow wrasse, grey gurnard and picarel and Hg in bogue may pose a risk for human health. Farmed and wild fish are good sources of P, K, Cr and Se while flathead grey mullet, picarel and comber are excellent sources of Ca and Se.

  20. Marine sediments and Beryllium-10 record of the geomagnetic moment variations during the Brunhes period.

    NASA Astrophysics Data System (ADS)

    Ménabréaz, Lucie; Thouveny, Nicolas; Bourlès, Didier; Demory, François

    2010-05-01

    Over millennial time scales, the atmospheric production of the cosmonuclid 10Be (half-life 1.387 ± 0.012 Ma [Shmeleff et al., 2009; Korschinek et al., 2009]) is modulated by the geomagnetic field strength, following a negative power law (e.g. Lal, 1988; Masarik and Beer, 2009). With respect to paleomagnetic reconstructions, 10Be-derived paleointensity records can therefore constitute an alternative, global and independent reading of the dipole moment variations. During the last years, efforts have been made to extract a geomagnetic signal from single and stacked 10Be records in natural archives such as ice and marine sediments (e.g. Carcaillet et al., 2004; Christl et al., 2007; Muscheler et al., 2005). In marine sediments, the 10Be concentration results from complex interplay of several processes: cosmogenic production, adsorption on sediment particles, redistribution by fluviatile and oceanic transport, and deposition. Therefore, a correction procedure is required to consider both sediment redistribution and enhanced scavenging, which can alter the primary signatures. To reconstruct the succession of field intensity lows accompanying excursions during the Brunhes chron, we investigated authigenic 10Be/9Be record of marine sequences also studied for paleomagnetism and oxygen isotopes. Mid and low latitude sites were preferred in order to benefit from the most efficient modulation by the magnetospheric shielding. We present a high resolution authigenic 10Be/9Be record of the last 50 ka recovered from the Portuguese Margin, that deciphers the cosmonuclide 10Be overproduction created by the geomagnetic dipole low associated with the Laschamp excursion. This record is compared to other proxy records of the geomagnetic field variations for the same time interval: (1) the relative paleointensity (RPI) reconstructed from the same sediments and the GLOPIS-75 record (Laj et al., 2004), (2) the absolute VDM record based on absolute paleointensities measured on lava flows

  1. Rock magnetic studies on marine volcaniclastic sediments off Martinique, Lesser Antilles volcanic arc, IODP Expedition 340

    NASA Astrophysics Data System (ADS)

    Saito, T.; Kataoka, K.

    2013-12-01

    Large numbers of marine volcaniclastic sediments with various origins were recovered from the sites U1397 and U1398 during IODP Expedition 340. They were most likely derived from volcanoes on Martinique and possibly from Dominica, Lesser Antilles volcanic arc. Some volcaniclastic units were transported and deposited as turbidites, some were as thin tephra fall deposits and others show both characteristics. They contain various amounts of bioclastic component, pumice and lithic fragments and hemipelagic mud clasts. Therefore, these volcaniclastic sediments are suitable for investigating transport and emplacement mechanisms of volcanic materials and the resultant sedimentary and petro-facies in marine settings. In this study, we focused on magnetic minerals in the marine volcaniclastic sediments and carried out rock magnetic measurements. Thermomagnetic measurements showed almost reversible curves and induced magnetization decayed to almost zero below 580 °C, suggesting little contribution of maghemite or hematite. Two Curie temperatures (Tc) with 350-400 °C and 500-550°C indicate that the main magnetic carriers are Ti-rich titanomagnetite and Ti-poor titanomagnetite. The proportion of low-Tc titanomagnetite in central and bottom part of turbidite units was larger than that in hemipelagic sediments and in the topmost part of turbidite units, suggesting Ti-rich titanomagnetite is derived from volcanic events. Magnetic susceptibility and hysteresis measurements showed that heavy and large magnetic minerals in most turbidite units were concentrated at the lower part of the unit. Samples from the topmost and bottom part of turbidites showed higher degrees of anisotropy than those from the central part, indicating strong influence of suspension settling at the topmost part and shearing at the bottom part. However, in some turbidite units such features cannot be observed and hysteresis parameters and susceptibility values were almost concentrated. Probably the units

  2. Chemoautotrophic carbon fixation rates and active bacterial communities in intertidal marine sediments.

    PubMed

    Boschker, Henricus T S; Vasquez-Cardenas, Diana; Bolhuis, Henk; Moerdijk-Poortvliet, Tanja W C; Moodley, Leon

    2014-01-01

    Chemoautotrophy has been little studied in typical coastal marine sediments, but may be an important component of carbon recycling as intense anaerobic mineralization processes in these sediments lead to accumulation of high amounts of reduced compounds, such as sulfides and ammonium. We studied chemoautotrophy by measuring dark-fixation of 13C-bicarbonate into phospholipid derived fatty acid (PLFA) biomarkers at two coastal sediment sites with contrasting sulfur chemistry in the Eastern Scheldt estuary, The Netherlands. At one site where free sulfide accumulated in the pore water right to the top of the sediment, PLFA labeling was restricted to compounds typically found in sulfur and ammonium oxidizing bacteria. At the other site, with no detectable free sulfide in the pore water, a very different PLFA labeling pattern was found with high amounts of label in branched i- and a-PLFA besides the typical compounds for sulfur and ammonium oxidizing bacteria. This suggests that other types of chemoautotrophic bacteria were also active, most likely Deltaproteobacteria related to sulfate reducers. Maximum rates of chemoautotrophy were detected in first 1 to 2 centimeters of both sediments and chemosynthetic biomass production was high ranging from 3 to 36 mmol C m(-2) d(-1). Average dark carbon fixation to sediment oxygen uptake ratios were 0.22±0.07 mol C (mol O2)(-1), which is in the range of the maximum growth yields reported for sulfur oxidizing bacteria indicating highly efficient growth. Chemoautotrophic biomass production was similar to carbon mineralization rates in the top of the free sulfide site, suggesting that chemoautotrophic bacteria could play a crucial role in the microbial food web and labeling in eukaryotic poly-unsaturated PLFA was indeed detectable. Our study shows that dark carbon fixation by chemoautotrophic bacteria is a major process in the carbon cycle of coastal sediments, and should therefore receive more attention in future studies on

  3. Chemoautotrophic carbon fixation rates and active bacterial communities in intertidal marine sediments.

    PubMed

    Boschker, Henricus T S; Vasquez-Cardenas, Diana; Bolhuis, Henk; Moerdijk-Poortvliet, Tanja W C; Moodley, Leon

    2014-01-01

    Chemoautotrophy has been little studied in typical coastal marine sediments, but may be an important component of carbon recycling as intense anaerobic mineralization processes in these sediments lead to accumulation of high amounts of reduced compounds, such as sulfides and ammonium. We studied chemoautotrophy by measuring dark-fixation of 13C-bicarbonate into phospholipid derived fatty acid (PLFA) biomarkers at two coastal sediment sites with contrasting sulfur chemistry in the Eastern Scheldt estuary, The Netherlands. At one site where free sulfide accumulated in the pore water right to the top of the sediment, PLFA labeling was restricted to compounds typically found in sulfur and ammonium oxidizing bacteria. At the other site, with no detectable free sulfide in the pore water, a very different PLFA labeling pattern was found with high amounts of label in branched i- and a-PLFA besides the typical compounds for sulfur and ammonium oxidizing bacteria. This suggests that other types of chemoautotrophic bacteria were also active, most likely Deltaproteobacteria related to sulfate reducers. Maximum rates of chemoautotrophy were detected in first 1 to 2 centimeters of both sediments and chemosynthetic biomass production was high ranging from 3 to 36 mmol C m(-2) d(-1). Average dark carbon fixation to sediment oxygen uptake ratios were 0.22±0.07 mol C (mol O2)(-1), which is in the range of the maximum growth yields reported for sulfur oxidizing bacteria indicating highly efficient growth. Chemoautotrophic biomass production was similar to carbon mineralization rates in the top of the free sulfide site, suggesting that chemoautotrophic bacteria could play a crucial role in the microbial food web and labeling in eukaryotic poly-unsaturated PLFA was indeed detectable. Our study shows that dark carbon fixation by chemoautotrophic bacteria is a major process in the carbon cycle of coastal sediments, and should therefore receive more attention in future studies on

  4. Non-destructive X-ray Computed Tomography (XCT) Analysis of Sediment Variance in Marine Cores

    NASA Astrophysics Data System (ADS)

    Oti, E.; Polyak, L. V.; Dipre, G.; Sawyer, D.; Cook, A.

    2015-12-01

    Benthic activity within marine sediments can alter the physical properties of the sediment as well as indicate nutrient flux and ocean temperatures. We examine burrowing features in sediment cores from the western Arctic Ocean collected during the 2005 Healy-Oden TransArctic Expedition (HOTRAX) and from the Gulf of Mexico Integrated Ocean Drilling Program (IODP) Expedition 308. While traditional methods for studying bioturbation require physical dissection of the cores, we assess burrowing using an X-ray computed tomography (XCT) scanner. XCT noninvasively images the sediment cores in three dimensions and produces density sensitive images suitable for quantitative analysis. XCT units are recorded as Hounsfield Units (HU), where -999 is air, 0 is water, and 4000-5000 would be a higher density mineral, such as pyrite. We rely on the fundamental assumption that sediments are deposited horizontally, and we analyze the variance over each flat-lying slice. The variance describes the spread of pixel values over a slice. When sediments are reworked, drawing higher and lower density matrix into a layer, the variance increases. Examples of this can be seen in two slices in core 19H-3A from Site U1324 of IODP Expedition 308. The first slice, located 165.6 meters below sea floor consists of relatively undisturbed sediment. Because of this, the majority of the sediment values fall between 1406 and 1497 HU, thus giving the slice a comparatively small variance of 819.7. The second slice, located 166.1 meters below sea floor, features a lower density sediment matrix disturbed by burrow tubes and the inclusion of a high density mineral. As a result, the Hounsfield Units have a larger variance of 1,197.5, which is a result of sediment matrix values that range from 1220 to 1260 HU, the high-density mineral value of 1920 HU and the burrow tubes that range from 1300 to 1410 HU. Analyzing this variance allows us to observe changes in the sediment matrix and more specifically capture

  5. A global perturbation to the sulfur cycle during the Toarcian Oceanic Anoxic Event

    NASA Astrophysics Data System (ADS)

    Gill, Benjamin C.; Lyons, Timothy W.; Jenkyns, Hugh C.

    2011-12-01

    The Mesozoic Era was punctuated by intervals of widespread anoxia within the ocean, termed oceanic anoxic events or OAEs. The chemostratigraphy of these intervals also contains evidence of transient perturbations to many biogeochemically important elemental cycles. Here we present high-resolution sulfur isotope data from three stratigraphic sections spanning the Toarcian Oceanic Anoxic Event (T-OAE) of the Early Jurassic. All sections show a similar increase in the sulfur isotope ratio of sulfate parallel to an overall positive excursion in carbon isotopes during the OAE interval. Based on forward box modeling, the sulfate-S isotope excursion can be generated by transiently increasing the burial rate of pyrite in marine sediments likely deposited under euxinic (i.e., anoxic and sulfidic) conditions in the water column. In addition, modeling shows that prolonged recovery of the δ 34S of seawater sulfate—at least 8 Ma after the initial rise associated with the OAE—was due to the relatively long residence time of sulfate in the Jurassic ocean; estimates from our modeling put the Toarcian marine sulfate concentrations at 4 to 8 mM. The similarity of the sulfur isotope records from the North European epicontinental (or epeiric) sea and Tethyan continental margin suggests that local modification of the marine sulfur isotope signal was minimal: a point explored with isotope mixing models. Importantly, our results indicate that the sulfur isotope excursion reflects a globally significant perturbation in the sulfur cycle and that pyrite burial in the North European Epeiric Seaway alone cannot account for the excursion. This study, along with recent work from other Phanerozoic intervals of widespread marine oxygen deficiency, confirms that the sulfur cycle can be perturbed significantly by enhanced pyrite burial during periods of prolonged oceanic anoxia/euxinia.

  6. Phosphate oxygen isotope ratio proxy for specific microbial activity in marine sediments (Peru Margin)

    NASA Astrophysics Data System (ADS)

    Liang, Y.; Blake, R. E.

    2005-12-01

    Oxygen (O) isotope ratios of biogenic apatites have been widely used as paleotemperature and environmental geochemical proxies. With improved knowledge of the phosphate O isotope effects of different P cycling pathways, the δ18O value of inorganic phosphate (δ18OP) has been proposed as a useful proxy and tracer of biological reactions and P cycling in natural environments[1,2,3,4]. Being the only way of removing P from oceanic water, sedimentary P burial is one of the most important processes during biogeochemical cycling of P. The high concentrations of organic matter and pronounced microbial activity at ODP Site 1230 along the Peru Margin result in unusually high interstitial water phosphate concentrations, which provides a unique opportunity to use δ18OP to investigate inorganic phosphate (Pi) regeneration and P cycling pathways in marine sediments. The isotopic measurements of both dissolved inorganic phosphate (DIP) and bulk sediment Pi show that DIP δ18OP values are affected by three different processes, which are all induced by specific microbial activities present in the sediments. In sediments at ~ 65 to 120 mbsf, porewater DIP is derived from dissolved organophosphorus compounds (DOP) through enzymatic degradation pathways, evidenced by both DIP δ18OP values and interstitial water chemistry. Measured porewater DIP δ18OP values also suggest that 4 to 8% of interstitial water DIP reflects regeneration of Pi from Porg by microbially-synthesized enzymes. Throughout the sediment column and especially at ~ 120 to 150 mbsf, DIP is released from the sediments by microbially-induced reductive dissolution of Fe-oxides, which contributes to the overall high DIP concentrations at Site 1230. The third and dominant process controlling measured DIP δ18OP values is microbial turnover of regenerated Pi. The presence of high microbial activities in organic-rich Site 1230 sediments promotes the remobilization of P and affects marine P cycling by potentially enhancing

  7. Hf and Nd isotopes in marine sediments: Constraints on global silicate weathering

    NASA Astrophysics Data System (ADS)

    Bayon, G.; Burton, K. W.; Soulet, G.; Vigier, N.; Dennielou, B.; Etoubleau, J.; Ponzevera, E.; German, C. R.; Nesbitt, R. W.

    2009-01-01

    The combined use of Lu-Hf and Sm-Nd isotope systems potentially offers a unique perspective for investigating continental erosion, but little is known about whether, and to what extent, the Hf-Nd isotope composition of sediments is related to silicate weathering intensity. In this study, Hf and Nd elemental and isotope data are reported for marine muds, leached Fe-oxide fractions and zircon-rich turbidite sands collected off the Congo River mouth, and from other parts of the SE Atlantic Ocean. All studied samples from the Congo fan (muds, Fe-hydroxides, sands) exhibit indistinguishable Nd isotopic composition (ɛ Nd ~ - 16), indicating that Fe-hydroxides leached from these sediments correspond to continental oxides precipitated within the Congo basin. In marked contrast, Hf isotope compositions for the same samples exhibit significant variations. Leached Fe-hydroxide fractions are characterized by ɛ Hf values (from - 1.1 to + 1.3) far more radiogenic than associated sediments (from - 7.1 to - 12.0) and turbidite sands (from - 27.2 to - 31.6). ɛ Hf values for Congo fan sediments correlate very well with Al/K (i.e. a well-known index for the intensity of chemical weathering in Central Africa). Taken together, these results indicate that (1) silicate weathering on continents leads to erosion products having very distinctive Hf isotope signatures, and (2) a direct relationship exists between ɛ Hf of secondary clay minerals and chemical weathering intensity. These results combined with data from the literature have global implications for understanding the Hf-Nd isotope variability in marine precipitates and sediments. Leached Fe-hydroxides from Congo fan sediments plot remarkably well on an extension of the 'seawater array' (i.e. the correlation defined by deep-sea Fe-Mn precipitates), providing additional support to the suggestion that the ocean Hf budget is dominated by continental inputs. Fine-grained sediments define a diffuse trend, between that for igneous

  8. Salinity Effects on the Biogeochemical Cycles of Sulfate, Arsenate, Nitrate, and Methane in Anoxic Sediments of Mono Lake and Searles Lake, California.

    NASA Astrophysics Data System (ADS)

    Kulp, T. R.; Hoeft, S. E.; Miller, L. G.; Oremland, R. S.

    2005-12-01

    Mono Lake and Searles Lake are two members of a chain of hypersaline and alkaline soda lakes that occur in closed basins along the arid eastern escarpment of the Sierra Nevada in California. These lakes are alkaline (pH = 9.8), highly saline, and As-rich due to hydrothermal input and evaporative concentration. Mono Lake is characterized by a salinity of 90 g/L and contains 200μM dissolved As. Searles Lake, a partially-dry residual playa, exhibits salt concentrations >300 g/L (near saturation) and 3.9 mM dissolved As. We utilized 35SO4 and 73As(V) as radioactive tracers to compare sulfate and arsenate [As(V)] reductase activities at in-situ concentrations in sediment cores (25 cm depth) from Mono and Searles Lakes. Sulfate reduction activity was detected in sediments from Mono Lake, with the highest rates occurring in the upper 2 cm sediment depth. No sulfate reduction activity was observed in Searles Lake sediments, suggesting that this metabolic process may not provide sufficient energy to cope with the demands of osmoadaptation at saturated salt concentrations. Anaerobic pathways that utilize As(V) or nitrate as terminal electron acceptors are bioenergetically more favorable than sulfate reduction. Dissimilatory reduction of As(V) occurred in sediments from both lakes, with the fastest rates of As(V) reduction occurring at 3 cm sediment depth. We conducted additional experiments with As- or nitrate-amended slurries of Searles Lake sediment prepared in artificial media that mimicked lake water chemistry over a range of total salinities. Slurries were sampled periodically and analyzed to determine the rate of As(V) reduction or denitrification at each salinity. Methane production was also monitored in the headspace of As(V)-amended and non-amended slurries. As(V) and nitrate reduction rates, as well as methane production, demonstrated an inverse relationship with total salinity over the range of 50 - 346 g/L. These data suggest that halophilic bacteria capable of

  9. Microbial processes and organic priority substances in marine coastal sediments (Adriatic Sea, Italy)

    NASA Astrophysics Data System (ADS)

    Zoppini, Annamaria; Ademollo, Nicoletta; Amalfitano, Stefano; Dellisanti, Walter; Lungarini, Silvia; Miserocchi, Stefano; Patrolecco, Luisa; Langone, Leonardo

    2015-04-01

    PERSEUS EU FP7 Project aims to identify the interacting patterns of natural and human-derived pressures to assess their impact on marine ecosystems and, using the objectives and principles of the Marine Strategy Framework Directive (MSFD) as a vehicle, to design an effective and innovative research governance framework based on sound scientific knowledge. In the frame of this Project (subtask 1.3.3 ADREX: Adriatic and Ionian Seas Experiment), monitoring surveys were conducted in the Adriatic Sea (Italy) in order to study the variation of structural and functional characteristics of native bacterial communities and the occurrence of selected classes of organic priority substances in sediments. The study area represents a good natural laboratory sensitive to climate variability and human pressure, owing to the semi-enclosed nature of the Adriatic Sea and to the increasing trend of human activities in the coastal regions. During the cruise ADRI-13 (November 2013) and ADRI-14 (October 2014) we sampled several coastal sites from the mouth of the Po River to the Otranto strait. Surface sediments were collected in all areas, while sediment cores were sampled in selected sites. Microbes associated with marine sediments play an important role in the C-flux being responsible for the transformation of organic detritus (autochthonous and allochthonous) into biomass. The sediment bacterial abundance was determined by epifluorescence microscopy and the rate of bacterial carbon production by measuring the 3H-leucine uptake rates. The community respiration rate was estimated by the measurement of the electron transport system (ETS) activity. The sediment contamination level was determined by measuring the concentration of contaminants included in the list of organic priority substances: PAHs, bisphenol A (BPA), alkylphenols (APs). The extraction/clean-up of PAHs, BPA and APs was performed by ultrasonic bath with the appropriate solvents, followed by analytical determination with

  10. Spatial, temporal, and source variations of hydrocarbons in marine sediments from Baffin Bay, Eastern Canadian Arctic.

    PubMed

    Foster, Karen L; Stern, Gary A; Carrie, Jesse; Bailey, Joscelyn N-L; Outridge, Peter M; Sanei, Hamed; Macdonald, Robie W

    2015-02-15

    With declining sea ice conditions in Arctic regions owing to changing climate, the large prospective reservoirs of oil and gas in Baffin Bay and Davis Strait are increasingly accessible, and the interest in offshore exploration and shipping through these regions has increased. Both of these activities are associated with the risk of hydrocarbon releases into the marine ecosystem. However, hydrocarbons are also present naturally in marine environments, in some cases deriving from oil seeps. We have analyzed hydrocarbon concentrations in eleven sediment cores collected from northern Baffin Bay during 2008 and 2009 Amundsen expeditions and have examined the hydrocarbon compositions in both pre- and post-industrial periods (i.e., before and after 1900) to assess the sources of hydrocarbons, and their temporal and spatial variabilities. Concentrations of ΣPAHs ranged from 341 to 2693 ng g(-1) dw, with concentrations in cores from sites within the North Water (NOW) Polynya generally higher. Individual PAH concentrations did not exceed concentrations of concern for marine aquatic life, with one exception found in a core collected within the NOW (one of the seven sediment core samples). Hydrocarbon biomarkers, including alkane profiles, OEP (odd-to-even preference), and TAR (terrigenous/aquatic ratios) values indicated that organic carbon at all sites is derived from both terrigenous higher plants and marine algae, the former being of greater significance at coastal sites, and the latter at the deepest sites at the southern boundary of the NOW. Biomarker ratios and chemical profiles indicate that petrogenic sources dominate over combustion sources, and thus long-range atmospheric transport is less significant than inputs from weathering. Present-day and historic pre-1900 hydrocarbon concentrations exhibited less than an order of magnitude difference for most compounds at all sites. The dataset presented here provides a baseline record of hydrocarbon concentrations in

  11. Spatial, temporal, and source variations of hydrocarbons in marine sediments from Baffin Bay, Eastern Canadian Arctic.

    PubMed

    Foster, Karen L; Stern, Gary A; Carrie, Jesse; Bailey, Joscelyn N-L; Outridge, Peter M; Sanei, Hamed; Macdonald, Robie W

    2015-02-15

    With declining sea ice conditions in Arctic regions owing to changing climate, the large prospective reservoirs of oil and gas in Baffin Bay and Davis Strait are increasingly accessible, and the interest in offshore exploration and shipping through these regions has increased. Both of these activities are associated with the risk of hydrocarbon releases into the marine ecosystem. However, hydrocarbons are also present naturally in marine environments, in some cases deriving from oil seeps. We have analyzed hydrocarbon concentrations in eleven sediment cores collected from northern Baffin Bay during 2008 and 2009 Amundsen expeditions and have examined the hydrocarbon compositions in both pre- and post-industrial periods (i.e., before and after 1900) to assess the sources of hydrocarbons, and their temporal and spatial variabilities. Concentrations of ΣPAHs ranged from 341 to 2693 ng g(-1) dw, with concentrations in cores from sites within the North Water (NOW) Polynya generally higher. Individual PAH concentrations did not exceed concentrations of concern for marine aquatic life, with one exception found in a core collected within the NOW (one of the seven sediment core samples). Hydrocarbon biomarkers, including alkane profiles, OEP (odd-to-even preference), and TAR (terrigenous/aquatic ratios) values indicated that organic carbon at all sites is derived from both terrigenous higher plants and marine algae, the former being of greater significance at coastal sites, and the latter at the deepest sites at the southern boundary of the NOW. Biomarker ratios and chemical profiles indicate that petrogenic sources dominate over combustion sources, and thus long-range atmospheric transport is less significant than inputs from weathering. Present-day and historic pre-1900 hydrocarbon concentrations exhibited less than an order of magnitude difference for most compounds at all sites. The dataset presented here provides a baseline record of hydrocarbon concentrations in

  12. Sediment Mediated Marine-derived Nutrient Transfers in Watersheds: the Dirt on Salmon Decay Products

    NASA Astrophysics Data System (ADS)

    Petticrew, Ellen; Albers, Sam

    2014-05-01

    The conveyance of nutrients and contaminants through aquatic systems is typically mediated by inorganic fine sediment. Its influence on the transfer of marine-derived nutrients through watersheds, however, is less well acknowledged. The ecological impact of the annual pulse of marine-derived nutrients (MDN) moved upstream into interior river systems via migrating salmon is thought to be significant as both local spawning reaches and the downstream nursery lakes have evidenced increased productivity following this nutrient pulse. The relationship between the number of upstream spawners and productivity in downstream nursery lakes is poorly defined as the conveyance of MDN between the two points of interest is influenced spatially and temporally by both channel and lake processes. A research project that specifically investigates the association between salmon decay products and sediment mediated transfers of these marine-derived nutrients downstream to the nursery lake is underway in the Horsefly River in British Columbia, an important sockeye river tributary to Quesnel Lake in the Canada's Fraser River watershed. Results from sampling freshet delivery to the lake in 2011 and 2012 will be presented as they represent two end members of the four year spawning cycle - snowmelt flushing following a high and low spawner return year. A continuous flow centrifuge was used to collect bulk suspended sediment 1) at points along the river, downstream of the spawning grounds, 2) along a transect from the river mouth where it enters Horsefly Bay and 3) at several other locations in the river plume during spring freshet. Stable isotopes (13C and 15N) were used to detect the MDN and chlorophyll a was analyzed to represent water column primary production. The relationships between sediment loads, nutrient delivery to the lake and primary productivity during this period will be presented in the context of upstream spawner biomass for both years.

  13. Cr Isotope Response to Ocean Anoxic Event 2

    NASA Astrophysics Data System (ADS)

    Holmden, C. E.; Jacobson, A. D.; Sageman, B. B.; Hurtgen, M.

    2015-12-01

    The element Cr offers a redox sensitive isotopic proxy with potential for tracing past oxygen levels in the oceans. We examine this potential in a marine carbonate section deposited during Cretaceous Ocean Anoxic Event 2 (OAE 2) in the Western Interior Seaway, Colorado. Redox changes are the main source of Cr isotope fractionation in Earth surface environments. Cr(VI), in the form of the chromate oxyanion, is the thermodynamically favoured species in oxygenated seawater. Reduction of Cr(VI) causes light isotopes to partition into Cr(III), which is reactive and susceptible to removal into marine sediment. Therefore, widespread ocean anoxia should correlate with positive shifts in seawater chromate Cr isotope values (δ53Cr), assuming that all Cr input fluxes remained constant during the event. We find instead that inferred seawater δ53Cr values decreased during OAE 2. The minima of the sedimentary δ53Cr excursion coincides with the peak interval of anomalously enriched concentrations of Cr and other trace metals of basaltic affinity attributed to eruption of the Caribbean Large Igneous Province (CLIP). We propose that an anoxic, hydrothermal plume enriched in Cr(III) with low δ53Cr values characteristic of igneous rocks moved from deep waters of the CLIP eruption site in the eastern Pacific into deep waters of the proto-North Atlantic through an oceanic gateway in the Central Americas. Once inside, metal-rich waters upwelled against the surrounding continental margins. CLIP volcanism delivered a submarine weathering flux of Cr to the oceans during OAE 2 that was large enough to mask the expected isotopic response of the ocean Cr cycle to increasing anoxia, particularly in the proto-North Atlantic Ocean.

  14. Glacial marine sediments in the precambrian Gowganda formation at Whitefish Falls, Ontario (Canada)

    USGS Publications Warehouse

    Lindsey, D.A.

    1971-01-01

    Study of a well-exposed section of the Gowganda Formation at Whitefish Falls, Ontario, suggests criteria for the recognition of glacial marine sediments. Thickness of hundreds of feet, lateral continuity, faint internal stratification, sorted lenses of sandstone and conglomerate, and dropstones characterize much of the tillite. Thickness of hundreds of feet, lateral continuity, and marked development of irregular and lenticular laminae instead of varve structure characterize much of the argillite. These characteristics, together with evidence for a nearshore, marine-to-deltaic environment for the overlying beds, suggest a glacial marine interpretation even though no fossil evidence is available. Massive tillite, tillite containing faint stratification and lenses of sorted conglomerate and sandstone, and dropstone-bearing argillite, all of which interfinger, suggest a glacial marine environment composed of: (1) a subglacial facies; (2) a periglacial facies; and (3) a facies of marine ice rafting, respectively. Separation of the two tillite-bearing members by as much as 700 ft. of argillite containing no dropstones suggests two distinct ice ages during Gowganda time. ?? 1971.

  15. Organomineral nanocomposite carbon burial during Oceanic Anoxic Event 2

    NASA Astrophysics Data System (ADS)

    Löhr, S. C.; Kennedy, M. J.

    2014-09-01

    Organic carbon (OC) enrichment in sediments deposited during Oceanic Anoxic Events (OAEs) is commonly attributed to elevated productivity and marine anoxia. We find that OC enrichment in the late Cenomanian aged OAE 2 at the Demerara Rise was controlled by the co-occurrence of anoxic bottom water, sufficient productivity to saturate available mineral surfaces, and variable deposition of high surface area detrital smectite clay. Redox indicators show consistently oxygen-depleted conditions, while a strong correlation between OC concentration and sediment mineral surface area (R2 = 0.92) occurs across a range of total organic carbon (TOC) values from 9 to 33%. X-ray diffraction data indicate the intercalation of OC in smectite interlayers, while electron, synchrotron infrared and X-ray microscopy show an intimate association between clay minerals and OC, consistent with preservation of OC as organomineral nanocomposites and aggregates rather than discrete, μm-scale pelagic detritus. Since the consistent ratio between TOC and mineral surface area suggests that excess OC relative to surface area is lost, we propose that it is the varying supply of smectite that best explains variable organic enrichment against a backdrop of continuous anoxia, which is conducive to generally high TOC during OAE 2 at the Demerara Rise. Smectitic clays are unique in their ability to form stable organomineral nanocomposites and aggregates that preserve organic matter, and are common weathering products of continental volcanic deposits. An increased flux of smectite coinciding with high carbon burial is consistent with evidence for widespread volcanism during OAE 2, so that organomineral carbon burial may represent a potential feedback to volcanic degassing of CO2.

  16. Organomineral nanocomposite carbon burial during Oceanic Anoxic Event 2

    NASA Astrophysics Data System (ADS)

    Löhr, S. C.; Kennedy, M. J.

    2014-05-01

    Organic carbon (OC) enrichment in sediments deposited during Oceanic Anoxic Events (OAEs) is commonly attributed to elevated productivity and marine anoxia. We find that OC enrichment in the late Cenomanian aged OAE2 at Demerara Rise was controlled by co-occurrence of anoxic bottom-water, sufficient productivity to saturate available mineral surfaces and variable deposition of high surface area detrital smectite clay. Redox indicators show consistently oxygen-depleted conditions, while a strong correlation between OC concentration and sediment mineral surface area (R2=0.92) occurs across a range of TOC values from 9-33%. X-ray diffraction data indicates intercalation of OC in smectite interlayers while electron, synchrotron infrared and X-ray microscopy show an intimate association between clay minerals and OC, consistent with preservation of OC as organomineral nanocomposites and aggregates rather than discrete, μm-scale pelagic detritus. Since the consistent ratio between TOC and mineral surface area suggests that excess OC relative to surface area is lost, we propose that it is the varying supply of smectite that best explains variable organic enrichment against a backdrop of continuous anoxia, which is conducive to generally high TOC during OAE2 at Demerara Rise. Smectitic clays are unique in their ability to form stable organomineral nanocomposites and aggregates that preserve organic matter, and are common weathering products of continental volcanic deposits. An increased flux of smectite coinciding with high carbon burial is consistent with evidence for widespread volcanism during OAE2, so that organomineral carbon burial may represent a potential feedback to volcanic degassing of CO2.

  17. Determination of metal components in marine sediments using energy-dispersive X-ray fluorescence (ED-XRF) spectrometry.

    PubMed

    Tung, Joanne Wai Ting

    2004-11-01

    A rapid energy-dispersive X-ray fluorescence (ED-XRF) spectrometric method for the analysis of metal components of marine sediments has been presented. Calibrations were made using synthetic matrix. The agreement of the results for sediment standard reference materials with reference values is satisfactory. Major advantages of the non-destructive ED-XRF technique over conventional chemical digestion methods include the applicability to analyzing the major oxide components, as well as to trace metals, and the avoidance of hazardous chemicals. The method has been applied to the routine analysis of Hong Kong marine sediment.

  18. Pleistocene reduction of polar ice caps: Evidence from Cariaco Basin marine sediments

    NASA Astrophysics Data System (ADS)

    Poore, R. Z.; Dowsett, H. J.

    2001-01-01

    Sea level is projected to rise between 13 and 94 cm over the next 100 yr due to continued climate warming. The sea-level projections assume that polar ice sheets will remain stable or even increase on time scales of centuries, but controversial geologic evidence suggests that current polar ice sheets have been eliminated or greatly reduced during previous Pleistocene interglacials indicating that modern polar ice sheets have become unstable within the natural range of interglacial climates. Sea level may have been more than 20 m higher than today during a presumably very warm interglacial about 400 ka during marine isotope stage 11. Because of the implications for future sea level rise, additional study of the conflicting evidence for warmer conditions and higher sea level during marine isotope stage 11 is needed. Here we present microfossil and isotopic data from marine sediments of the Cariaco Basin supporting the interpretation that global sea level was 10 20 m higher than today during marine isotope stage 11. The increased sea level requires reduction in modern polar ice sheets and is consistent with the interpretation that the West Antarctic ice sheet and the Greenland ice sheet were absent or greatly reduced during marine isotope stage 11. Our results show a warm marine isotope stage 11 interglacial climate with sea level as high as or above modern sea level that lasted for 25 to 30 k.y. Variations in Earth's orbit around the sun (Milankovitch cycles) are considered to be a primary external force driving glacial-interglacial cycles. Current and marine isotope stage 11 Milankovitch forcing are very similar, suggesting that the present interglacial (Holocene) that began ca. 10 ka will continue for another 15 to 20 k.y. Therefore any anthropogenic climate warming will accelerate the natural process toward reduction in polar ice sheets. The potential for increased rates of sea level rise related to polar ice sheet decay should be considered as a potential natural

  19. Pleistocene reduction of polar ice caps: Evidence from Cariaco Basin marine sediments

    USGS Publications Warehouse

    Poore, R.Z.; Dowsett, H.J.

    2001-01-01

    Sea level is projected to rise between 13 and 94 cm over the next 100 yr due to continued climate warming. The sea-level projections assume that polar ice sheets will remain stable or even increase on time scales of centuries, but controversial geologic evidence suggests that current polar ice sheets have been eliminated or greatly reduced during previous Pleistocene interglacials indicating that modern polar ice sheets have become unstable within the natural range of interglacial climates. Sea level may have been more than 20 m higher than today during a presumably very warm interglacial about 400 ka during marine isotope stage 11. Because of the implications for future sea level rise, additional study of the conflicting evidence for warmer conditions and higher sea level during marine isotope stage 11 is needed. Here we present microfossil and isotopic data from marine sediments of the Cariaco Basin supporting the interpretation that global sea level was 10-20 m higher than today during marine isotope stage 11. The increased sea level requires reduction in modern polar ice sheets and is consistent with the interpretation that the West Antarctic ice sheet and the Greenland ice sheet were absent or greatly reduced during marine isotope stage 11. Our results show a warm marine isotope stage 11 interglacial climate with sea level as high as or above modern sea level that lasted for 25 to 30 k.y. Variations in Earth's orbit around the sun (Milankovitch cycles) are considered to be a primary external force driving glacial-interglacial cycles. Current and marine isotope stage 11 Milankovitch forcing are very similar, suggesting that the present interglacial (Holocene) that began ca. 10 ka will continue for another 15 to 20 k.y. Therefore any anthropogenic climate warming will accelerate the natural process toward reduction in polar ice sheets. The potential for increased rates of sea level rise related to polar ice sheet decay should be considered as a potential natural

  20. Contamination of port zone sediments by metals from Large Marine Ecosystems of Brazil.

    PubMed

    Buruaem, Lucas M; Hortellani, Marcos A; Sarkis, Jorge E; Costa-Lotufo, Leticia V; Abessa, Denis M S

    2012-03-01

    Sediment contamination by metals poses risks to coastal ecosystems and is considered to be problematic to dredging operations. In Brazil, there are differences in sedimentology along the Large Marine Ecosystems in relation to the metal distributions. We aimed to assess the extent of Al, Fe, Hg, Cd, Cr, Cu, Ni, Pb and Zn contamination in sediments from port zones in northeast (Mucuripe and Pecém) and southeast (Santos) Brazil through geochemical analyses and sediment quality ratings. The metal concentrations found in these port zones were higher than those observed in the continental shelf or the background values in both regions. In the northeast, metals were associated with carbonate, while in Santos, they were associated with mud. Geochemical analyses showed enrichments in Hg, Cd, Cu, Ni and Zn, and a simple application of international sediment quality guidelines failed to predict their impacts, whereas the use of site-specific values that were derived by geochemical and ecotoxicological approaches seemed to be more appropriate in the management of the dredged sediments. PMID:22306311

  1. Recognizing magnetostratigraphy in overprinted and altered marine sediments: Challenges and solutions from IODP Site U1437

    NASA Astrophysics Data System (ADS)

    Musgrave, Robert J.; Kars, Myriam

    2016-08-01

    Core disturbance, drilling overprints, postdepositional acquisition of remanence, authigenic growth of magnetic iron sulfides, and alteration all contribute challenges to recognizing the primary magnetostratigraphy in marine sediments. We address these issues in a sequence of tuffaceous muds and volcaniclastics at International Ocean Discovery Program Site U1437 and produce the longest continuous magnetic polarity stratigraphy in the history of scientific ocean drilling. Remanence measurements were filtered to remove intervals affected by fluidization, plastic sediment disturbance, and core biscuiting. Drilling overprints are concentrated in the disturbed annulus surrounding intact core material. Bioturbation was limited to a vertical extent of at most 15 cm. Changes in sediment color, stiffness, and magnetic hysteresis all suggest that remanence was locked in within a few meters of the sediment-water interface. We did not observe any systematic offset between magnetostratigraphic and biostratigraphic datums. Authigenic growth of greigite, in response to both initial sulfate reduction in the upper 50 m of the sediment column and to deeper resupply of sulfate, has led to magnetic overprinting. Anomalous polarity artefacts, extending <5 m and occurring within about 20 m below a real polarity transition, appear to be due to a chemical remanence acquired by greigite produced during early diagenesis. Diagenetic magnetic mineral alteration resulted in the progressive loss of fine-grained magnetite, which enhanced susceptibility to drilling and postdrilling overprints and increased the resistance of these overprints to removal by conventional demagnetization. We recovered the magnetostratigraphic record from many samples with resistant overprints through low-temperature demagnetization through the Verwey transition.

  2. An integrated bioremediation process for petroleum hydrocarbons removal and odor mitigation from contaminated marine sediment.

    PubMed

    Zhang, Zhen; Lo, Irene M C; Yan, Dickson Y S

    2015-10-15

    This study developed a novel integrated bioremediation process for the removal of petroleum hydrocarbons and the mitigation of odor induced by reduced sulfur from contaminated marine sediment. The bioremediation process consisted of two phases. In Phase I, acetate was dosed into the sediment as co-substrate to facilitate the sulfate reduction process. Meanwhile, akaganeite (β-FeOOH) was dosed in the surface layer of the sediment to prevent S(2-) release into the overlying seawater. In Phase II, NO3(-) was injected into the sediment as an electron acceptor to facilitate the denitrification process. After 20 weeks of treatment, the sequential integration of the sulfate reduction and denitrification processes led to effective biodegradation of total petroleum hydrocarbons (TPH), in which about 72% of TPH was removed. In Phase I, the release of S(2-) was effectively controlled by the addition of akaganeite. The oxidation of S(2-) by Fe(3+) and the precipitation of S(2-) by Fe(2+) were the main mechanisms for S(2-) removal. In Phase II, the injection of NO3(-) completely inhibited the sulfate reduction process. Most of residual AVS and S(0) were removed within 4 weeks after NO3(-) injection. The 16S rRNA clone library-based analysis revealed a distinct shift of bacterial community structure in the sediment over different treatment phases. The clones affiliated with Desulfobacterales and Desulfuromonadales were the most abundant in Phase I, while the clones related to Thioalkalivibrio sulfidophilus, Thiohalomonas nitratireducens and Sulfurimonas denitrificans predominated in Phase II.

  3. Redox effects on the microbial degradation of refractory organic matter in marine sediments

    NASA Astrophysics Data System (ADS)

    Reimers, Clare E.; Alleau, Yvan; Bauer, James E.; Delaney, Jennifer; Girguis, Peter R.; Schrader, Paul S.; Stecher, Hilmar A.

    2013-11-01

    Microbially mediated reduction-oxidation (redox) reactions are often invoked as being the mechanisms by which redox state influences the degradation of sedimentary organic matter (OM) in the marine environment. To evaluate the effects of elevated, oscillating and reduced redox potentials on the fate of primarily aged, mineral-adsorbed OM contained in continental shelf sediments, we used microbial fuel cells to control redox state within and around marine sediments, without amending the sediments with reducing or oxidizing substances. We subsequently followed electron fluxes in the redox elevated and redox oscillating treatments, and related sediment chemical, isotopic and bacterial community changes to redox conditions over a 748-day experimental period. The electron fluxes of the elevated and oscillating redox cells were consistent with models of organic carbon (OC) oxidation with time-dependent first-order rate constants declining from 0.023 to 0.005 y-1, in agreement with rate constants derived from typical OC profiles and down core ages of offshore sediments, or from sulfate reduction rate measurements in similar sediments. Moreover, although cumulative electron fluxes were higher in the continuously elevated redox treatment, incremental rates of electron harvesting in the two treatments converged over the 2 year experiment. These similar rates were reflected in chemical indicators of OM metabolism such as dissolved OC and ammonia, and particulate OC concentrations, which were not significantly different among all treatments and controls over the experimental time-scale. In contrast, products of carbonate and opal dissolution and metal mobilization showed greater enrichments in sediments with elevated and oscillating redox states. Microbial community composition in anode biofilms and surrounding sediments was assessed via high-throughput 16S rRNA gene sequencing, and these analyses revealed that the elevated and oscillatory redox treatments led to the

  4. Development of marine sediment bioassays and toxicity tests for monitoring and regulation in Europe

    SciTech Connect

    Thain, J.; Matthiessen, P.

    1995-12-31

    There is a need in Europe and elsewhere for a broad suite of whole-sediment bioassays and toxicity tests which can be used for routine monitoring and assessment of the marine environment and for evaluating the toxic effects of chemicals which may find their way into sediments. Until recently, few European species had been incorporated into such tests but the availability of suitable methodologies is now increasing rapidly. Perhaps the most important recent activity in this area consisted of an international ring test of acute sediment toxicity test methods which was organized by the Oslo and Paris Commissions in 1993, using up to 4 offshore chemicals as test materials. It evaluated the performance of 4 acute (5--10 day) tests involving: the sea urchin Echinocardium cordatum, the bivalve mollusc Abra alba, the amphipod crustacean Corophium volutator, and the polychaete worm Arenicola marina. The ring test concluded that the C. volutator test was the most appropriate for evaluating offshore chemicals, but all these methods are now widely used in Europe, both as toxicity tests and as bioassays. For example, the A. marina procedure (which has both lethal and sublethal endpoints), in combination with the C. volutator method, is now routinely used in the UK for monitoring the toxicity of estuarine sediments. Further activities are in progress. Perhaps the most important is the development of chronic marine sediment tests and bioassays which can be used to assess the long-term effects of the many sedimentary contaminants which are able to persist in this type of habitat and possibly cause delayed effects on the growth and reproduction, etc. of benthic fauna.

  5. Control of organic matter on the magnetic properties of surficial marine sediments. A simple kinetic model

    NASA Astrophysics Data System (ADS)

    Mohamed Falcon, K. J.; Andrade, A.; Rey, D.; Rubio, B.

    2014-12-01

    Magnetic properties of marine sediments in the Galician Rias, in NW Spain, have shown that in these shallow marine settings the magnetic mineral assemblage, and its bulk magnetic properties, is controlled by grain size, wave climate, and organic matter content. The grain size effect is explained by concentration of diamagnetic biogenic carbonates in the coarse fraction, which dilutes the concentration-dependent magnetic properties. Furthermore, this effect is enhanced by the hydrodynamic sorting of the heavy minerals, like magnetite, that become concentrated in the finer fractions. Waves on the other hand concentrate the coarser bioclasts in the shallower areas along the coastal margins of the rias, and consequently these areas show the lowest magnetic mineral concentrations. Magnetic minerals are therefore more abundant in the deeper central axis and towards the external, more oceanic, areas of the rias. Another effect of waves is periodic resuspension of fine sediments, which allows them to be reoxigenated preventing the onset of reductive diagenesis. This effect is best seen in sediment cores, where organic matter remineralization promotes dissolution of magnetic iron oxides and oxyhydroxides. Areas where resuspension is frequent and/or deeper areas where sediments stay in the water column for longer have lower degrees of reductive early diagenesis. In addition to its downcore effect, organic matter also controls the magnetic properties of surficial sediments. Our results in the Ria de Muros, at the north of our study area, have shown that a simple kinetic model is enough to quantify the effect of organic matter content on the dissolution of magnetite. We have found that a Total Organic Carbon increase of 0.35% reduces magnetite concentration of surface samples by half. These effects observed in the Ria de Muros have also been confirmed for published results in the southern Rias Baixas previously studied by our research group.

  6. Estimation of hydrogen sulfide removal efficiency with granulated coal ash applied to eutrophic marine sediment using a simplified simulation model.

    PubMed

    Asaoka, Satoshi; Yamamoto, Tamiji; Yamamoto, Hironori; Okamura, Hideo; Hino, Kazutoshi; Nakamoto, Kenji; Saito, Tadashi

    2015-05-15

    Hydrogen sulfide generated in eutrophic marine sediment is harmful for living organisms. It is therefore necessary to remove hydrogen sulfide from the sediment to restore benthic ecosystems. Previous studies revealed that granulated coal ash, which is a by-product of coal thermal electric power stations, could remove and oxidize hydrogen sulfide. In this study, we propose a simplified simulation model to estimate the hydrogen sulfide removal efficiency of granulated coal ash. Hydrogen sulfide concentrations in eutrophic marine sediment pore water with and without the application of granulated coal ash were calculated by the proposed model, and the outputs were compared with semi-field or field observation data. The model outputs reproduced the observed data well. Using the proposed model outputs, we suggest an optimum application dosage of granulated coal ash for remediating eutrophic marine sediment.

  7. Effects of biogenic silica on acoustic and physical properties of clay-rich marine sediments

    SciTech Connect

    Tribble, J.S.; Mackenzie, F.T.; Urmos, J.; O'Brien, D.K.; Manghnani, M.H. )

    1992-06-01

    The physical properties of marine sediments are influenced by compaction and diagenesis during burial. Changes in mineralogy, chemistry, density, porosity, and microfabric all affect a sediment's acoustic and electrical properties. Sediments from the Japan Trench illustrate the dependence of physical properties on biogenic silica content. Increased opal-A content is correlated with increased porosity and decreased grain density and compressional velocity. Variations with depth in opal-A concentration are therefore reflected in highly variable and, at times, inverse velocity-depth gradients. The diagenetic conversion of opal-A to opal-CT and finally to quartz was investigated at a site in the San Miguel Gap, California. Distinct changes in microfabric, particularly in the porosity distribution, accompany the diagenetic reactions and contribute to a sharp velocity discontinuity at the depth of the opal-A to opal-CT conversion. Evaluation of this reaction at several sites indicates a systematic dependence on temperature and age in clay-rich and moderately siliceous sediments. In ocean margin regions, sediments are buried rapidly, and opal-A may be converted to opal-CT in less than 10 m.y. Temperatures of conversion range from 30{degree} to 50{degree}C. Much longer times (>40 m.y.) are required to complete the conversion in open ocean deposits which are exposed to temperatures less than 15{degree}C. In the absence of silica diagenesis, velocity-depth gradients of most clay-rich and moderately siliceous sediments fall in the narrow range of 0.15 to 0.25 km/s/km which brackets the gradient (0.18 km/s/km) determined for a type pelagic clay section. Relationships such as these can be useful in unraveling the history of a sediment sequence, including the evolution with time of reservoir properties and seismic signatures.

  8. Toxicological and chemical assessment of ordnance compounds in marine sediments and porewaters

    USGS Publications Warehouse

    Nipper, M.; Carr, R.S.; Biedenbach, J.M.; Hooten, R.L.; Miller, K.

    2002-01-01

    Toxicological and chemical studies were performed with a silty and a sandy marine sediment spiked with 2,6-dinitrotoluene (2,6-DNT), 2,4,6-trinitrophenylmethylnitramine (tetryl), or 2,4,6-trinitrophenol (picric acid). Whole sediment toxicity was analyzed by the 10-day survival test with the amphipod Ampelisca abdita, and porewater toxicity tests assessed macro-algae (Ulva fasciata) zoospore germination and germling growth, sea urchin (Arbacia punctulata) embryological development, and polychaete (Dinophilus gyrociliatus) survival and reproduction. Whole sediments spiked with 2,6-DNT were not toxic to amphipods. The fine-grained sediment spiked with tetryl was also not acutely toxic. The tetryl and picric acid LC50 values in the sandy sediment were 3.24 and 144 mg/kg dry weight, respectively. The fine-grained sediment spiked with picric acid generated a U-shaped concentration-response curve in the amphipod test, with increased survival both in the lowest and highest concentration. Grain-size distribution and organic carbon content strongly influenced the behavior of ordnance compounds in spiked sediments. Very low concentrations were measured in some of the treatments and irreversible binding and biodegradation are suggested as the processes responsible for the low measurements. Porewater toxicity varied with its sedimentary origin and with ordnance compound. The sea urchin embryological development test tended to be the least sensitive. Tetryl was the most toxic chemical in all porewater tests, and picric acid the least toxic. Samples spiked with 2,6-DNT contained a degradation product identified as 2-methyl-3-nitroaniline (also known as 2-amino-6-nitrotoluene), and unidentified peaks, possibly degradation products, were also seen in some of the picric acid- and tetryl-spiked samples. Degradation products may have played a role in observed toxicity. ?? 2002 Elsevier Science Ltd. All rights reserved.

  9. Geochemical Evidence for Recent Hydrothermal Alteration of Marine Sediments in Mid-Okinawa Trough, Southwest Japan

    NASA Astrophysics Data System (ADS)