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Sample records for anoxic marine sediments

  1. Diagenetic isotope effects in an anoxic marine sediment

    International Nuclear Information System (INIS)

    The carbon isotope effects associated with the remineralization of organic matter in the anoxic sediments of Cape Lookout Bight, NC, have been investigated. Total organic carbon δ13C profiles and an isotopic mass balance of the diagenetic products, σCO2 and methane, indicate that the initial step in the breakdown of the organic matter, i.e. the transformation of biopolymeric material to biomonomers, does not express a significant isotope effect. Intramolecular δ13C measurements of the diagenetic intermediate, acetate indicates that large isotope effects (5-10 per-thousand) occur during the biosynthesis of that compound. Downcore δ13C variations in the acetate appear to be related to fractionations associated with methanogenesis. The fractionation factor for the conversion of the acetate methyl group to methane has been estimated to be 1.02 from the porewater profiles

  2. Decomposition of algal lipids in clay-enriched marine sediment under oxic and anoxic conditions

    Institute of Scientific and Technical Information of China (English)

    吕冬伟; 宋茜; 王旭晨

    2010-01-01

    A series of laboratory incubation experiments were conducted to examine the decomposition of algal organic matter in clay-enriched marine sediment under oxic and anoxic conditions.During the 245-day incubation period,changes in the concentrations of TOC,major algal fatty acid components (14:0,16:0,16:1,18:1 and 20:5),and n-alkanes (C16-C23) were quantified in the samples.Our results indicate that the organic matters were degraded more rapidly in oxic than anoxic conditions.Adsorption of fatty acids onto cla...

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

    Science.gov (United States)

    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

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

    International Nuclear Information System (INIS)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Maria eGenovese

    2014-04-01

    Full Text Available 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 1,000 kg of sediments collected in Messina harbor were spiked with Bunker C furnace fuel oil (6,500 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 three 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 three 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 one 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.

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

    Science.gov (United States)

    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

  9. Acetate consumption in anoxic marine sediments: Identification of key players using mixed pure cultures and sediment incubations

    DEFF Research Database (Denmark)

    Na, Hyunsoo

    at 10 mM acetate-2 mM (low) sulfate and lower (0.1 and 1 mM) acetate-high sulfate conditions, as revealed by Ion Torrent sequencing of 16S rRNA gene sequences. At 0.1 and 1 mM acetate concentrations, members of the phyla Firmicutes (Fusibacter-related), Fusobacteria, and Bacteroidetes were...... here the flexibility of the microbial communities in response to different geochemical conditions, in high resolution, with biological replicates, using Ion Torrent sequencing. Secondly, we used two different sediment incubation techniques, dialysis tube batch and continuous flow-through bioreactors...

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

    Science.gov (United States)

    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).

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

    Science.gov (United States)

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

    2016-01-01

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

  12. Release of metals from anoxic sediment

    DEFF Research Database (Denmark)

    Larsen, Martin Mørk; Jacobsen, Gitte

    sediment surface and the top of the water column on day 1, 4, 8 and 12, and the results for V, Mn, Co, Ni, Cu, Zn, Cd, Pb and Fe will be presented, together with indication of statistically significant increase in concentration between the different groups of treatment. The water was clear over both groups...... without crabs, but cloudy, indicating re-suspension in the group with crabs. The metal release from sediments will be discussed in the context of re-oxygenation of anoxic or low-oxic sediments and the effect of organism that digs into the sediment in recently re-oxidised bottom waters....

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

    OpenAIRE

    MariaGenovese; DanielaRusso; AlfonsoModica; LauraGiuliano; PeterN.Golyshin

    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 1,000 kg of sediments collected in Messina harbor were spiked with Bunker C furnace fuel oil (6,500 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 three months of ageing, the anaerobic s...

  14. Long distance electron transmission in marine sediment

    DEFF Research Database (Denmark)

    Risgaard-Petersen, Nils; Nielsen, Lars Peter

    Geochemical observations in marine sediment have recently shown that electric currents may intimately couple spatially separated biogeochemical processes like oxygen reduction at the sediment surface and hydrogen sul-phide oxidation in anoxic layers centimeters below 1. Further experimental studi...... the system. Long distance electron transmission may flourishes in marine sediments exposed to tran-sient oxygen depletion, leaving distinct signatures of such events in the geological record....

  15. An open marine record of the Toarcian oceanic anoxic event

    Directory of Open Access Journals (Sweden)

    D. R. Gröcke

    2011-04-01

    Full Text Available Oceanic anoxic events were time intervals in the Mesozoic characterized by widespread distribution of marine organic-rich sediments (black shales and significant perturbations in the global carbon cycle. The expression of these perturbations is globally recorded in sediments as excursions in the carbon isotope record irrespective of lithology or depositional environment. During the Early Toarcian, black shales were deposited on the epi- and peri-continental shelves of Pangaea and these sedimentary rocks are associated with a pronounced (ca. 7‰ negative (organic carbon isotope excursion (CIE which is thought to be the result of a major perturbation in the global carbon cycle. For this reason, the Early Toarcian is thought to represent an oceanic anoxic event (the T-OAE. Associated with this event, there were pronounced perturbations in global weathering rates and seawater temperatures. Although it is commonly asserted that the T-OAE is a global event and that the distribution of black shales is likewise global, an isotopic and/or organic-rich expression of this event has as yet only been recognized on epi- and peri-continental Pangaean localities. To address this issue, the carbon isotope composition of organic matter (δ13Corg of Early Toarcian cherts from Japan that were deposited in the open Panthalassa Ocean was analysed. The results show the presence of a major (>6‰ negative excursion in δ13Corg that, based on radiolarian biostratigraphy, is a correlative of the Early Toarcian negative CIE known from European epicontinental strata. Furthermore, a secondary ca. −2‰ excursion in δ13Corg is also recognized lower in the studied succession that, within the current biostratigraphical resolution, is likely to represent the excursion that occurs close to the Pliensbachian/Toarcian boundary and which is also recorded in European epicontinental successions

  16. Biogeochemistry of pyrite and iron sulfide oxidation in marine sediments

    DEFF Research Database (Denmark)

    Schippers, A.; Jørgensen, BB

    2002-01-01

    Pyrite (FeS2) and iron monosulfide (FeS) play a central role in the sulfur and iron cycles of marine sediments, They may be buried in the sediment or oxidized by O-2 after transport by bioturbation to the sediment surface. FeS2 and FeS may also be oxidized within the anoxic sediment in which NO3-...

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

    Science.gov (United States)

    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.

  18. H2 cycling and microbial bioenergetics in anoxic sediments

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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, ...

  1. Predictive isotopic biogeochemistry: hydrocarbons from anoxic marine basins

    Science.gov (United States)

    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.

  2. Metatranscriptomic insights into polyphosphate metabolism in marine sediments.

    Science.gov (United States)

    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. PMID:26381585

  3. Massive expansion of marine archaea during a mid-Cretaceous oceanic anoxic event

    DEFF Research Database (Denmark)

    Kuypers, M.M.M.; Blokker, P.; Erbacher, J.;

    2001-01-01

    Biogeochemical and stable carbon isotopic analysis of black-shale sequences deposited during an Albian oceanic anoxic event (∼112 million years ago) indicate that up to 80 weight percent of sedimentary organic carbon is derived from marine, nonthermophilic archaea. The carbon-13 content of archaeal...... molecular fossils indicates that these archaea were living chemoautotrophically. Their massive expansion may have been a response to the strong stratification of the ocean during this anoxic event. Indeed, the sedimentary record of archaeal membrane lipids suggests that this anoxic event marks a time in...... Earth history at which certain hyperthermophilic archaea adapted to low-temperature environments....

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

    Science.gov (United States)

    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

  5. Anoxic N-2 fluxes from freshwater sediments in the absence of oxidized nitrogen compounds.

    NARCIS (Netherlands)

    Luijn, F.; Boers, P.C.M.; Lijklema, L.

    1998-01-01

    From anoxic incubated freshwater sediments, initially without inorganic nitrogen compounds in the overlying water, remarkable and unexpected N2 fluxes were estimated. N2 leakage from the atmosphere and oxygen leakage followed by nitrification and denitrification, two possible causes, were thoroughly

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

    Directory of Open Access Journals (Sweden)

    Y.-S. Lin

    2010-04-01

    Full Text Available In anoxic environments, volatile methylated sulfides including methanethiol (MT and dimethyl sulfide (DMS link the pools of inorganic and organic carbon with the sulfur cycle. However, direct formation of methylated sulfides from reduction of dissolved inorganic carbon has previously not been demonstrated. During examination of the hydrogenotrophic microbial activity at different temperatures in the anoxic sediment from Lake Plußsee, DMS formation was detected at 55 °C and was enhanced when bicarbonate was supplemented. Addition of both bicarbonate and H2 resulted in the strongest stimulation of DMS production, and MT levels declined slightly. Addition of methyl-group donors such as methanol and syringic acid or methyl-group acceptors such as hydrogen sulfide did not enhance further accumulation of DMS and MT. The addition of 2-bromoethanesulfonate inhibited DMS formation and caused a slight MT accumulation. MT and DMS had average δ13C values of −55‰ and −62‰, respectively. Labeling with NaH13CO3 showed that incorporation of bicarbonate into DMS occurred through methylation of MT. H235S labeling demonstrated a microbially-mediated, but slow, process of hydrogen sulfide methylation that accounted for <10% of the accumulation rates of DMS. Our data suggest: (1 methanogens are involved in DMS formation from bicarbonate, and (2 the major source of the 13C-depleted MT is neither bicarbonate nor methoxylated aromatic compounds. Other possibilities for isotopically light MT, such as demethylation of 13C-depleted DMS or other organic precursors such as methionine, are discussed. This DMS-forming pathway may be relevant for anoxic environments, such as hydrothermally influenced sediments and fluids and sulfate-methane transition zones in marine sediments.

  7. Black carbon in marine sediments

    NARCIS (Netherlands)

    Middelburg, J.J.; Nieuwenhuize, J.; Van Breugel, P.

    1999-01-01

    Concentrations of black carbon were determined for a number of marine sediments. A comparison of black carbon based on thermal oxidation and hot concentrated nitric acid pretreatments revealed that the latter significantly overestimates combustion derived carbon phases. Black carbon accounts for abo

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

    Science.gov (United States)

    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

  9. ENAA Studies of pollution in anoxic Black Sea sediments

    International Nuclear Information System (INIS)

    The vertical distributions of five potential pollutants - Zn, As, Br, Sn, and Sb - were determined via epithermal neutron activation in the upper 50 cm of unconsolidated sediments from the Black Sea, which were collected 600 m 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 137Cs as a time marker allowed for dating of this region to the last 100 years.

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

    DEFF Research Database (Denmark)

    Arnosti, Carol; Finke, Niko; Larsen, Ole;

    2005-01-01

    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...... of carbon degradation diverged, with an additional 43%, 32%, 33%, and 8% of Isochrysis, Iso-Ex, Spirulina, and Spir-Ex carbon respired to CO2 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 CO2. In contrast, only 15% of Spir-Ex carbon was respired, despite the...

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

    Science.gov (United States)

    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

  12. Recycling and burial of phosphorus in sediments of an anoxic fjord-the By Fjord, western Sweden

    DEFF Research Database (Denmark)

    Viktorsson, Lena; Kononets, Mikhail; Roos, Per;

    2013-01-01

    water. The water in the basin is exchanged only every 3 to 5 years and the water below sill level is anoxic or sulfidic between water renewals. Five sites were examined in the By Fjord; three shallow sites above the sill level with oxic bottom waters and two deeper sites with anoxic bottom waters....... Contents of sediment organic carbon, total nitrogen and organic phosphorus were higher at deep stations when compared to shallow ones, whereas the contents of sediment inorganic phosphorus was higher at shallow than at deep stations both in surficial and buried sediment. One shallow oxic site and one deep...... fluxes from sediments with anoxic overlying water (1.25-2.26 mmol m(-2) d(-1)). The DIP flux increased with increasing flux of dissolved inorganic carbon (DIC) not only at anoxic but also at oxic bottoms, which is different from observations in brackish water environments. The average ratio between the...

  13. Siderite formation in anoxic deep-sea sediments: A synergetic bacterially controlled process with important implications in paleomagnetism

    Energy Technology Data Exchange (ETDEWEB)

    Ellwood, B.B.; Chrzanowski, T.H. (Univ. of Texas, Arlington (USA)); Hrouda, F. (Geofyzika, Brno (Czechoslovakia)); Long, G.J.; Buhl, M.L. (Univ. of Missouri, Rolla (USA))

    1988-11-01

    Recent work on magnetic properties of limestones has demonstrated that the mineral siderite can be very important in paleomagnetism, for two reasons. First, oxidation of siderite produces secondary (daughter) magnetic minerals (magnetite, maghemite, and hematite), either before, during, or after sampling. These daughter products can completely change the magnetic properties of limestone samples and if unrecognized may be one of the primary reasons why many paleomagnetic studies of limestones, especially Paleozoic limestones, are unsuccessful. Second, siderite in weakly magnetized rocks may indicate the potential for successful paleomagnetic results. Because the presence of siderite indicates that the primary magnetic carriers are still intact, appropriate demagnetization methods should yield successful results. The authors conclude that microenvironmental conditions in anoxic marine sediments may permit the formation of siderite from iron (II) produced during bacterial dissimilatory iron reduction.

  14. Radionuclide interactions with marine sediments

    International Nuclear Information System (INIS)

    A critical review of the literature on the subject of the interactions of radionuclides with marine sediments has been carried out. On the basis of the information available, an attempt has been made to give ranges and 'best estimates' for the distribution ratios between seawater and sediments. These estimates have been based on an understanding of the sediment seawater system and the porewater chemistry and mineralogy. Field measurements, laboratory measurements and estimates based on stable-element geochemical data are all taken into account. Laboratory measurements include distribution-ratio and diffusion-coefficient determinations. The elements reviewed are carbon, chlorine, calcium, nickel, selenium, strontium, zirconium, niobium, technetium, tin, iodine, caesium, lead, radium, actinium, thorium, protactinium, uranium, neptunium, plutonium, americium and curium. (author)

  15. Exposure of an anoxic and contaminated canal sediment: Mobility of metal(loid)s

    International Nuclear Information System (INIS)

    A derelict canal contains an estimated 9800 tonnes of anoxic sediment with highly elevated concentrations of trace elements. Lack of maintenance, reduced water levels and vegetation colonization threaten the stability of pollutants by removing existing waterlogged reduced conditions. A column leaching study of the sediment under increasingly oxidized conditions showed reductions in As mobility but increased heavy metal concentrations. In a reduced state, As mobility was higher (as a consequence of enhanced Fe and organic carbon solubility) whilst heavy metal concentrations in leachates were lower (due to markedly higher pH). Over 10 contiguous wetting and drying cycles, the consequences were profound; all trace elements were continuously leached with enhanced flushing of Fe, As, Zn and Cu. This raises concern over possible mobilization of pollutants to the wider environment, including groundwater. Options for management to stabilize contaminants are discussed that point to the importance of limiting water flow through the sediment. - Wetting and drying enhance contaminant mobility in an urban canal sediment.

  16. Long distance electron transmission couples sulphur, iron, calcium and oxygen cycling in marine sediment

    DEFF Research Database (Denmark)

    Risgaard-Petersen, Nils; Nielsen, Lars Peter

    Geochemical observations in marine sediment have recently documented that electric currents may intimately couple spatially separated biogeochemical processes (1). When marine sediment rich in iron sulphide was exposed to oxygen we observed how the electric currents resulted in significant...... geochemical alterations in the upper centimetres of the anoxic sediment: Sulphides were oxidized to sulphate in anoxic sediment layers. Electrons from this half-reaction were passed to the oxic layers cm above. In this way the domain of oxygen was extended far beyond it’s physically presence. Bioelectrical...... from iron sulfides was to a large extend deposited in the oxic zone as iron oxides and Ca2+ eventually precipitates at the surface as due to high pH caused by cathodic oxygen reduction. The result show how long distance electron transmission allows oxygen to drive the allocation of important minerals...

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

    Directory of Open Access Journals (Sweden)

    Y. S. Lin

    2010-08-01

    isotopically depleted MT, such as other organic precursors like methionine, are discussed. This DMS-forming pathway may be relevant for anoxic environments such as hydrothermally influenced sediments and fluids and sulfate-methane transition zones in marine sediments.

  18. Diverse methane concentrations in anoxic brines and underlying sediments, eastern Mediterranean Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Karisiddaiah, S.M.

    of the brines are extremely high, 2692]103 nM at 3493m, and are 20 times higher than the Bannock Basin values. Thus, based on available physical pro"les (oxygen, temperature and salinity) of water masses in these brines, the approximate boundary of the brine... Atlantis II (mer Rouge). Oceanologica Acta 13, 187}197. Boldrin, A., Rabitti, S., 1990. Hydrography of the brines in the Bannock and Tyro anoxic basins (Eastern Mediterranean). Marine Chemistry 31, 21}33. Camerlenghi, A., Cita, M.B., Hieke, W., Ricchuito, T...

  19. Phosphorus, carbon and nitrogen enrichment during sedimentation in a seasonally anoxic lake (Lake Lugano, Switzerland

    Directory of Open Access Journals (Sweden)

    Kurt W. Hanselmann

    2002-08-01

    Full Text Available Sedimentation fluxes of major nutrients are investigated during 1996 and 1997 at three different depths and two locations in eutrophic southern basin of Lake Lugano (Switzerland. Horizontal differences between the two sites are on the order of 10-40% (but can exceed 50%, whereas differences related to interannual oscillations range between 5 and 24%. Particulate organic carbon (POC and nitrogen (PN fluxes show a constant increase of 5-20% from the upper to the bottom trap. This tendency remains more or less constant during the year. On the contrary, particulate phosphorus (PP shows a seasonal variation, with higher accumulation rates from the I to the III trap in autumn and winter which can exceed +1200%. This phenomenon is due to the interaction between the dissolved phosphorus (DP and the iron(oxihydroxides (Fe(OH3 near the oxycline. Fe(OH3 precipitates at the iron redox boundary, scavenging DP. This enrichment flux increases together with the development of the anoxic benthic layer. The efficiency of the iron redox layer in trapping upward diffusing P is related to the concentration of dissolved iron in the anoxic hypolimnion. In Lake Lugano the two considered sites present major difference of iron concentration, and this difference is reflected in the P sedimentation fluxes. The exposition of an additional sedimentation trap above the maximal oxycline height has allowed to gain insight into this phenomenon.

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

    Science.gov (United States)

    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.

  1. Seasonal dynamics of ammonia/ammonium-oxidizing prokaryotes in oxic and anoxic wetland sediments of subtropical coastal mangrove

    OpenAIRE

    Wang, Yong-Feng; Feng, Yao-Yu; Ma, Xiaojun; Gu, Ji-Dong

    2012-01-01

    Mangrove wetlands are an important ecosystem in tropical and subtropical regions, and the sediments may contain both oxic and anoxic zones. In this study, ammonia/ammonium-oxidizing prokaryotes (AOPs) in yellow and black sediments with vegetation and non-vegetated sediments in a mangrove wetland of subtropical Hong Kong were investigated in winter and summer. The phylogenetic diversity of anammox bacterial 16S rRNA genes and archaeal and bacterial amoA genes (encoding ammonia monooxygenase al...

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

    International Nuclear Information System (INIS)

    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. - Highlights: ► Bioremediation performance was investigated on hydrocarbon contaminated sediments. ► Major changes in bacterial diversity and assemblage composition were observed. ► Temperature exerted the major effect on bacterial assemblages. ► High bacterial diversity increased significantly biodegradation performance. This should be considered for sediment remediation by bio-treatments. - Bioremediation strategies which can sustain high levels of bacterial diversity may significantly increase the biodegradation of hydrocarbons in contaminated marine sediments.

  3. Isolation of Cellulolytic Actinomycetes from Marine Sediments

    OpenAIRE

    Veiga, Manuel; Esparis, Azucena; Fabregas, Jaime

    1983-01-01

    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.

  4. Diversity, Persistence and Evolution in Marine Sediments

    DEFF Research Database (Denmark)

    Starnawski, Piotr

    2016-01-01

    . No evidence for selection of repair and recombination functions in the deeper sediment was found, and high number of motility and chemotaxis was detected through the sediment column. This work casts new light on marine sediment communities, describes their vertical structure and assembly in detail......72 % of our planet is covered by saline water, which at its bottom gradually forms a layer of deposited material. This layer of marine sediments harbors active and diverse prokaryotic communities, of which we know little more than just the phylogenetical associ- ation with their often distant...... treat the whole community as equal, not knowing who and what are the contributions of hydrolyzers, fermenters and terminal oxidizers. In order to address these unknowns I have focused my work on three main aspects of the marine sediments: (i) systematic, analytical description of the microbial...

  5. Partition of iodine (129I and 127I) isotopes in soils and marine sediments

    International Nuclear Information System (INIS)

    Natural organic matter, such as humic and fulvic acids and humin, plays a key role in determining the fate and mobility of radioiodine in soil and sediments. The radioisotope 129I is continuously produced and released from nuclear fuel reprocessing plants, and as a biophilic element, its environmental mobility is strongly linked to organic matter. Due to its long half-life (15.7 million years), 129I builds up in the environment and can be traced since the beginning of the nuclear era in reservoirs such as soils and marine sediments. Nevertheless, partition of the isotope between the different types of organic matter in soil and sediment is rarely explored. Here we present a sequential extraction of 129I and 127I chemical forms encountered in a Danish soil, a soil reference material (IAEA-375), an anoxic marine sediment from Southern Norway and an oxic sediment from the Barents Sea. The different forms of iodine are related to water soluble, exchangeable, carbonates, oxides as well as iodine bound to humic acid, fulvic acid and to humin and minerals. This is the first study to identify 129I in humic and fulvic acid and humin. The results show that 30-56% of the total 127I and 42-60% of the total 129I are associated with organic matter in soil and sediment samples. At a soil/sediment pH below 5.0-5.5, 127I and 129I in the organic fraction associate primarily with the humic acid while at soil/sediment pH > 6 129I was mostly found to be bound to fulvic acid. Anoxic conditions seem to increase the mobility and availability of iodine compared to oxic, while subaerial conditions (soils) reduces the availability of water soluble fraction compared to subaqueous (marine) conditions. - Highlights: → Chemical speciation of 129I and 127I in soil and sediment. → Association of 129I with humic substances in soil and marine sediments is reported. → Partition of iodine within the organic fraction depends on soil/sediment pH. → Anoxic conditions seem to increase the mobility

  6. Partition of iodine ({sup 129}I and {sup 127}I) isotopes in soils and marine sediments

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Violeta, E-mail: violeta.hansen@risoe.dk [Riso National Laboratory for Sustainable Energy, NUK-202, Technical University of Denmark, Frederiksborgvej 399, P.O.B. 49, DK-4000 Roskilde (Denmark); Roos, Per [Riso National Laboratory for Sustainable Energy, NUK-202, Technical University of Denmark, Frederiksborgvej 399, P.O.B. 49, DK-4000 Roskilde (Denmark); Aldahan, Ala [Department of Earth Science, Uppsala University, SE-758 36 Uppsala (Sweden); Department of Geology, United Arab Emirates University, Al Ain (United Arab Emirates); Hou, Xiaolin [Riso National Laboratory for Sustainable Energy, NUK-202, Technical University of Denmark, Frederiksborgvej 399, P.O.B. 49, DK-4000 Roskilde (Denmark); Possnert, Goeran [Tandem Laboratory, Uppsala University, SE-751 21 Uppsala (Sweden)

    2011-12-15

    Natural organic matter, such as humic and fulvic acids and humin, plays a key role in determining the fate and mobility of radioiodine in soil and sediments. The radioisotope {sup 129}I is continuously produced and released from nuclear fuel reprocessing plants, and as a biophilic element, its environmental mobility is strongly linked to organic matter. Due to its long half-life (15.7 million years), {sup 129}I builds up in the environment and can be traced since the beginning of the nuclear era in reservoirs such as soils and marine sediments. Nevertheless, partition of the isotope between the different types of organic matter in soil and sediment is rarely explored. Here we present a sequential extraction of {sup 129}I and {sup 127}I chemical forms encountered in a Danish soil, a soil reference material (IAEA-375), an anoxic marine sediment from Southern Norway and an oxic sediment from the Barents Sea. The different forms of iodine are related to water soluble, exchangeable, carbonates, oxides as well as iodine bound to humic acid, fulvic acid and to humin and minerals. This is the first study to identify {sup 129}I in humic and fulvic acid and humin. The results show that 30-56% of the total {sup 127}I and 42-60% of the total {sup 129}I are associated with organic matter in soil and sediment samples. At a soil/sediment pH below 5.0-5.5, {sup 127}I and {sup 129}I in the organic fraction associate primarily with the humic acid while at soil/sediment pH > 6 {sup 129}I was mostly found to be bound to fulvic acid. Anoxic conditions seem to increase the mobility and availability of iodine compared to oxic, while subaerial conditions (soils) reduces the availability of water soluble fraction compared to subaqueous (marine) conditions. - Highlights: > Chemical speciation of {sup 129}I and {sup 127}I in soil and sediment. > Association of {sup 129}I with humic substances in soil and marine sediments is reported. > Partition of iodine within the organic fraction depends

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  9. Radionuclide sorption by marine sediments

    International Nuclear Information System (INIS)

    The effect of the solid/solution ratio on distribution ratios measured using a standard batch technique was investigated. Two different deep-sea sediments and the actinides americium, neptunium and plutonium were studied. It is shown that the apparent drop in distribution ratio with increasing sediment concentration can frequently be explained by the presence of a small amount of non-separable or 'low-Rsub(d)' species and that by measuring the Rsub(d) at different solid/solution ratios it is possible to estimate the proportion of low-Rsub(d) species present. These may be colloids or stable complexes. Plutonium exhibited anomalous behaviour with the high-carbonate sediment and the distribution ratio dropped from > 104 to 102 as the solid/soln ratio increased from 2g/l to 20g/l. At high sediment concentrations the plutonium in solution was mainly in the oxidised Pu(V + VI) form and it is postulated that Pu-VI carbonates were the main species present. (author)

  10. Uranium and plutonium in marine sediments

    International Nuclear Information System (INIS)

    The marine sediments contain uranium concentrations that are considered normal, since the seawater contains dissolved natural uranium that is deposited in the bed sea in form of sediments by physical-chemistry and bio-genetics processes. Since the natural uranium is constituted of several isotopes, the analysis of the isotopic relationship 234U/238U are an indicator of the oceanic activity that goes accumulating slowly leaving a historical registration of the marine events through the profile of the marine soil. But the uranium is not the only radioelement present in the marine sediments. In the most superficial strata the presence of the 239+140Pu has been detected that it is an alpha emitter and that recently it has been detected with more frequency in some coasts of the world. The Mexican coast has not been the exception to this phenomenon and in this work the presence of 239-140Pu is shown in the more superficial layers of an exploring coming from the Gulf of Tehuantepec. (Author)

  11. Mercury in dated Greenland marine sediments

    DEFF Research Database (Denmark)

    Asmund, G.; Nielsen, S.P.

    2000-01-01

    Twenty marine sediment cores from Greenland were analysed for mercury, and dated by the lead-210 method. In general the cores exhibit a mercury profile with higher mercury concentrations in the upper centimetres of the core. The cores were studied by linear regression of In Hg vs, age of the...... sediment for the youngest 100 years. As a rule the mercury decreased with depth in the sediment with various degrees of significance. The increase of the mercury flux during the last 100 years is roughly a doubling. The increase may be of anthropogenic origin as it is restricted to the last 100 years. In...... four cores the concentration of manganese was found also to increase in the top layers indicating diagenesis. In the other cases the higher concentrations were not accompanied by higher manganese concentrations. The mercury flux to the sediment surface was generally proportional to the Pb-210 flux...

  12. Modeling sediment deposition from marine outfall jets.

    Science.gov (United States)

    Terfous, Abdelali; Chiban, Samia; Ghenaim, Abdellah

    2016-08-01

    This paper presents a two-dimensional model to study the sediment deposition from marine outfall jets. The introduced unidirectional coupling (fluid-sediment) is an appropriate choice in the case of low-concentrated particle-laden jets such as municipal wastewater discharge, where the concentration of particles is small enough and does not affect the hydrodynamic development of the jet in the nearfield. The sedimentation model takes advantage of the preferential concentration phenomenon. The deposition criterion states that the deposition of sediments begins when the vertical component of the entrainment velocity becomes smaller than the settling velocity. Once the deposition process begins, it is controlled by the settling velocity, entrainment velocity, volume flux, and sediment concentration. The deposition along the jet trajectory is expressed by an ordinary differential equation coupled with the liquid phase equations. Experiments of Lane-Serff and Moran [Sedimentation from Buoyant jets. J Hyd Eng. 2005;131(3):166-174], Cuthbertson and Davies [Deposition from particle-laden, round, turbulent, horizontal, buoyant jets in stationary and coflowing receiving fluids. J Hydr Eng. 2008;134(4):390-402], and Lee [Mixing of horizontal sediment laden jets [dissertation]. Hong Kong: University of Hong Kong; 2010], chosen from bibliography, are used to validate the model. These experiments cover the cases of horizontal and inclined buoyant jets in stationary ambient, horizontal buoyant jets in co-flow current and nonbuoyant horizontal jets in stationary ambient. Good agreement between the experiments and the obtained simulations is revealed. PMID:26732467

  13. A comparison of an optimised sequential extraction procedure and dilute acid leaching of elements in anoxic sediments, including the effects of oxidation on sediment metal partitioning

    International Nuclear Information System (INIS)

    The effect of oxidation of anoxic sediment upon the extraction of 13 elements (Cd, Sn, Sb, Pb, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As) using the optimised Community Bureau of Reference of the European Commission (BCR) sequential extraction procedure and a dilute acid partial extraction procedure (4 h, 1 mol L-1 HCl) was investigated. Elements commonly associated with the sulfidic phase, Cd, Cu, Pb, Zn and Fe exhibited the most significant changes under the BCR sequential extraction procedure. Cd, Cu, Zn, and to a lesser extent Pb, were redistributed into the weak acid extractable fraction upon oxidation of the anoxic sediment and Fe was redistributed into the reducible fraction as expected, but an increase was also observed in the residual Fe. For the HCl partial extraction, sediments with moderate acid volatile sulfide (AVS) levels (1-100 μmol g-1) showed no significant difference in element partitioning following oxidation, whilst sediments containing high AVS levels (>100 μmol g-1) were significantly different with elevated concentrations of Cu and Sn noted in the partial extract following oxidation of the sediment. Comparison of the labile metals released using the BCR sequential extraction procedure (ΣSteps 1-3) to labile metals extracted using the dilute HCl partial extraction showed that no method was consistently more aggressive than the other, with the HCl partial extraction extracting more Sn and Sb from the anoxic sediment than the BCR procedure, whilst the BCR procedure extracted more Cr, Co, Cu and As than the HCl extraction

  14. Modeling nonlinear compressional waves in marine sediments

    OpenAIRE

    McDonald, B E

    2009-01-01

    A computational model is presented which will help guide and interpret an upcoming series of experiments on nonlinear compressional waves in marine sediments. The model includes propagation physics of nonlinear acoustics augmented with granular Hertzian stress of order 3/2 in the strain rate. The model is a variant of the time domain NPE (McDonald and Kuperman, 1987) supplemented with a causal algorithm for frequency-linear attenuation. When attenuation is absent, the model ...

  15. Modeling nonlinear compressional waves in marine sediments

    OpenAIRE

    McDonald, B E

    2009-01-01

    A computational model is presented which will help guide and interpret an upcoming series of experiments on nonlinear compressional waves in marine sediments. The model includes propagation physics of nonlinear acoustics augmented with granular Hertzian stress of order 3/2 in the strain rate. The model is a variant of the time domain NPE (McDonald and Kuperman, 1987) supplemented with a causal algorithm for frequency-linear attenuation. When attenuation is absent, the model equations are used...

  16. The anoxic stress conditions explored at the nanoscale by atomic force microscopy in highly eutrophic and sulfidic marine lake

    Science.gov (United States)

    Marguš, M.; Morales-Reyes, I.; Bura-Nakić, E.; Batina, N.; Ciglenečki, I.

    2015-10-01

    Marine Rogoznica lake (RL), an eutrophic and euxinic environment situated at the eastern Adriatic coast was used as a natural laboratory to test the application of atomic force microscopy (AFM) in combination with the electrochemical and high temperature catalytic oxidation (HTCO) measurements for characterization of water column organic matter (OM) and reduced sulfur species (RSS) in relation to seasonal changes of environmental conditions. Water column of RL was explored at the nanoscale by the AFM during the anoxic holomictic event (S1, October 2011) and stratified winter (S2, January 2012) and spring (S3, May 2012) conditions in the oxic and anoxic water samples. Obtained results from the AFM uphold the electrochemical and HTCO measurements, indicating significant difference in the present type of OM during the holomictic, anoxic stress conditions in comparison to the samples collected during the stratification period. Differences in the OM type were discussed in line with the physical and biological processes that occurred in RL during sampling: mixing processes characterized by fast turnover of water layers and biological activity characterized by low (January 2012) and high (May 2012) primary production of diatoms and zooplankton grazing activities.

  17. Biodegradation of crude oil in different types of marine sediment

    International Nuclear Information System (INIS)

    An active oil-oxidizing bacterium, named Nap C was isolated from the sediment sample of Port Dickson coastal area for this study. Nap C is a gram negative, rod shape marine bacterium. It forms spore when the condition is not favorable. Three different types of treated marine sediment; sand, silt and clay were used in this study. The degradation of Malaysian Tapis A crude oil in the different types of marine sediment were assessed. Silt type of marine sediment was found to sustain highest biodegradation compared to clay type and sand type. 8.6.67% of the Malaysian Tapis A crude oil was degraded in silt type of marine sediment within 10 days of incubation. Where as there were only 60% and 73% of the Malaysian Tapis A crude oil was degraded in sand and clay type of marine sediment respectively. Microbial biomass estimation in the sediment was estimated by indirect phospholipid enumeration technique. (author)

  18. Characterization of marine sediments using analytical techniques

    International Nuclear Information System (INIS)

    This study deals with the characterization of a marine sediments profile from the Gulf of Tehuantepec, Mexico. Ten sediment samples obtained from a core of 18.3 m of length were analysed. Although there have been numerous marine sediments studies carried out in Mexico, more are needed to better understand the sea floor formation. Crystallographic, morphologic, physical, chemical and gamma ray activity analysis were carried out on the samples. The analysis results showed a decrease in organic matter content as a function of sea depth; this value is related to the specific surface area. Some hazardous materials as Cr, Mn, Ni, Sr and Hg were also identified by PIXE in some samples, probably due to anthropogenic activity. The presence of uranium a naturally occurring element was found in all the samples, suggesting a migration through all materials of strata, radioactive elements such as 226Ra, 235U, 212Pb, 214Pb, 228Ac, 208Ti, 214Bi, 228Ac and 40K were detected. (author)

  19. Partition of iodine (129I and 127I) isotopes in soils and marine sediments

    DEFF Research Database (Denmark)

    Hansen, Violeta; Roos, Per; Aldahan, Ala;

    2011-01-01

    Natural organic matter, such as humic and fulvic acids and humin, plays a key role in determining the fate and mobility of radioiodine in soil and sediments. The radioisotope 129I is continuously produced and released from nuclear fuel reprocessing plants, and as a biophilic element, its environm......Natural organic matter, such as humic and fulvic acids and humin, plays a key role in determining the fate and mobility of radioiodine in soil and sediments. The radioisotope 129I is continuously produced and released from nuclear fuel reprocessing plants, and as a biophilic element, its...... environmental mobility is strongly linked to organic matter. Due to its long half-life (15.7 million years), 129I builds up in the environment and can be traced since the beginning of the nuclear era in reservoirs such as soils and marine sediments. Nevertheless, partition of the isotope between the different...... types of organic matter in soil and sediment is rarely explored. Here we present a sequential extraction of 129I and 127I chemical forms encountered in a Danish soil, a soil reference material (IAEA-375), an anoxic marine sediment from Southern Norway and an oxic sediment from the Barents Sea. The...

  20. Coastal marine sediment sampling for radionuclide analysis

    International Nuclear Information System (INIS)

    January 1968, a B52 plane carrying 4 nuclear weapons crashed on the sea ice ∼12 km from the Thule Air Base, Northwest Greenland. The benthic marine environment in the 180-230 m deep Bylot Sound was then contaminated with ∼1.4 TBq 239,240Pu (∼0.5 kg). The site was revisited August 1997. Due to the single plutonium injection well defined in time the site is an interesting test case for sediment dating. The present data support an earlier quantification of the sedimentation rate as 3-4 mm per year, i.e. 8-12 cm during the 29 years since the accident. Biological activity has mixed accident plutonium much deeper, down to 20-30 cm, and the 8-12 cm new sediment have been efficiently mixed into the contaminated layer. In addition to the classical bioturbation mixing the upper ∼ 5 cm, the plutonium data indicates the existence of a deeper mixing, probably also caused by bioturbation. This could have implications for the use of excess 210Pb as a sedimentation rate chronometer in coastal environments with rich biological activity. (author)

  1. Sediment Burial Intolerance of Marine Macroinvertebrates.

    Science.gov (United States)

    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. Sediment Burial Intolerance of Marine Macroinvertebrates.

    Directory of Open Access Journals (Sweden)

    Vicki J Hendrick

    Full Text Available 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

  3. Nonlinear acoustics of water-saturated marine sediments

    DEFF Research Database (Denmark)

    Jensen, Leif Bjørnø

    1976-01-01

    Interest in the acoustic qualities of water-saturated marine sediments has increased considerably during recent years. The use of sources of high-intensity sound in oil propsecting, in geophysical and geological studies of bottom and subbottom materials and profiles and recently in marine...... archaeology has emphasized the need of information about the nonlinear acoustic qualities of water-saturated marine sediments. While the acoustic experiments and theoretical investigations hitherto performed have concentrated on a determination of the linear acoustic qualities of water-saturated marine...... sediments, their parameters of nonlinear acoustics are still unexplored. The strong absorption, increasing about linearly with frequency, found in most marine sediments and the occurrence of velocity dispersion by some marine sediments restrict the number of nonlinear acoustic test methods traditionally...

  4. PO4 release at the sediment surface under anoxic conditions: a contribution to the eutrophication of the Baltic Sea?

    Directory of Open Access Journals (Sweden)

    Bernd Schneider

    2011-05-01

    Full Text Available The vertical profiles of phosphate, total CO2 and oxygen/hydrogen sulphide were determined in the deep water of the Gotland Sea during March 2003 to July 2006 with a temporal resolution of 2-3 months. This time span included the shift from anoxic to oxic conditions resulting from a water renewal event, as well as the transition back to anoxic waters during the subsequent two-year stagnation period. The data from depths below 150 m were used to identify and quantify phosphate release and removal processes. The relationship between the total CO2 generated by mineralization (CT, min and the PO4 concentrations indicated that the initial decrease in the phosphate concentrations after the inflow of oxygen-rich water was mainly a dilution effect. Only about one third of the PO4 removal was a consequence of the precipitation of insoluble iron-3-hydroxo-phosphates (Fe-P, which occurred slowly at the sediment surface under oxic conditions. From the CT, min/PO4 ratios it was also concluded that the formation of Fe-P was reversed during the later phase of the stagnation, when the redoxcline approached a depth of 150 m. A phosphate mass balance was performed for four deep water sub-layers in order to quantify the dissolution of Fe-P during the stagnation period and thus to estimate the amount of Fe-P deposited during the last inflow of oxygen-rich water. A value of about 50 mmol-P m-2 was found, which refers to the specific biogeochemical conditions during the change from anoxic to oxic conditions that preceded the stagnation period.

  5. Millimeter-scale alkalinity measurement in marine sediment using DET probes and colorimetric determination.

    Science.gov (United States)

    Metzger, E; Viollier, E; Simonucci, C; Prévot, F; Langlet, D; Jézéquel, D

    2013-10-01

    Constrained DET (Diffusive Equilibration in Thin films) probes equipped with 75 sampling layers of agarose gel (DGT Research(©)) were used to sample bottom and pore waters in marine sediment with a 2 mm vertical resolution. After retrieval, each piece of hydrogel, corresponding to 25 μL, was introduced into 1 mL of colorimetric reagent (CR) solution consisting of formic acid and bromophenol blue. After the elution/reaction time, absorbance of the latter mixture was read at 590 nm and compared to a calibration curve obtained with the same protocol applied to mini DET probes soaked in sodium hydrogen carbonate standard solutions. This method allows rapid alkalinity determinations for the small volumes of anoxic pore water entrapped into the gel. The method was assessed on organic-rich coastal marine sediments from Thau lagoon (France). Alkalinity values in the overlying waters were in agreement with data obtained by classical sampling techniques. Pore water data showed a progressive increase of alkalinity in the sediment from 2 to 10 mmol kg(-1), corresponding to anaerobic respiration in organic-rich sediments. Moreover, replicates of high-resolution DET profiles showed important lateral heterogeneity at a decimeter scale. This underlines the importance of high-resolution spatial methods for alkalinity profiling in coastal marine systems. PMID:23870435

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

    International Nuclear Information System (INIS)

    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. - Highlights: • Anionic surfactant SAS can be anaerobically degraded in marine sediments. • Degradation is strongly influenced by the sorption capacity of SAS homologues. • Oxidation of SAS alkyl chain takes place by means of fumarate addition. • Carboxylic acids are formed during the anaerobic degradation of SAS. - Anaerobic degradation of SAS in marine sediments and the metabolites involved in this process are reported for the first time

  7. Distribution of uranium in marine sediments

    International Nuclear Information System (INIS)

    The marine sediments obtained by means of a sampling nucleus in the Gulf of Tehuantepec, Mexico, they have been object of crystallographic and morphological characterization. The PIXE analysis of some samples in study is shown. The normal methodology to carry out the alpha spectroscopy indicates that the sample should be dissolved, but due to the nature of the marine sediments, it thinks about the necessity to make a fractional separation of the sample components. In each stratum of the profile it separates the organic part and the mineral to recover the uranium. It was observed that in the organic phase, the uranium is in two oxidation states (IV and Vl), being necessary the radiochemical separation with a liquid/liquid column chromatographic that uses the di-2-ethyl hexyl phosphoric acid as stationary phase. The uranium compounds extracts are electrodeposited in fine layers on stainless steel disks to carry out the analysis by alpha spectroscopy. The spectroscopic analysis of the uranium indicates us that for each stratum one has a difference marked in the quotient of activities of 234U/238U that depends on the nature of the studied fraction. These results give us a clear idea about how it is presented the effect of the uranium migration and other radioelements in the biosphere, with what we can determine which are the conditions in that these have their maximum mobility and to know their diffusion patterns in the different media studied. (Author)

  8. Anoxic incubation of sediment in gas-tight plastic bags: a method for biogeochemical process studies

    DEFF Research Database (Denmark)

    Hansen, JW; Thamdrup, B.; Jørgensen, BB

    2000-01-01

    Incubation of sediment in gas-tight plastic bags is described as a method for experimental studies of biogeochemical processes. Sediment incubation in these bags allows time-course experiments to be conducted on homogenised sediment without dilution, continuous stirring, or gaseous head......-space. Consequently, bag incubations of sediment combine the advantage of low heterogeneity in slurry incubations with the more natural conditions in jar and whole-core incubations. The bag material is a transparent laminated plastic comprised of Nylon, ethylenevinyl alcohol, and polyethylene with a low permeability...... for the studied gases: O-2, CO2, H2S, CH4, N-2, H-2, and He. Estimated fluxes of biologically active gases through the plastic bag during sediment incubation were insignificant compared to rates of microbial processes and to gas concentrations in coastal sediments. An exception was CH4, for which process...

  9. Organic carbon degradation in arctic marine sediments, Svalbard: A comparison of initial and terminal steps

    DEFF Research Database (Denmark)

    Arnosti, C.; Jørgensen, BB

    2006-01-01

    carbohydrate concentrations were comparable to those measured in more temperate sediments, and likely comprise a considerable fraction of porewater dissolved organic carbon. A comparison of dissolved carbohydrate inventories with hydrolysis and sulfate reduction rates suggests that the turnover of carbon......Degradation of marine organic matter under anoxic conditions involves microbial communities working in concert to remineralize complex substrates to CO2. In order to investigate the coupling between the initial and terminal steps of this sequence in permanently cold sediments, rates of...... extracellular enzymatic hydrolysis and sulfate reduction were measured in parallel cores collected from 5 fjords on the west and northwest coast of Svalbard, in the high Arctic. Inventories of total dissolved carbohydrates were also measured in order to evaluate their potential role in carbon turnover...

  10. Characterization of marine near-surface sediments by electromagnetic profiling

    OpenAIRE

    Müller, Hendrik

    2010-01-01

    This thesis investigates the theory, develops the technology and demonstrates the applicabilities for synchronous in-situ mapping of the magnetic and electric signatures of marine near-surface sediments. A marine electromagnetic profiler has been developed for coastal and shelf operations in 5 to 500 m water depths. The system was designed to resolve subtle and gradual variations in silt and clay content, porosity and diagenesis state of marine sediments at a sub-meter scale. An electromagnet...

  11. Modeling nonlinear compressional waves in marine sediments

    Directory of Open Access Journals (Sweden)

    B. E. McDonald

    2009-02-01

    Full Text Available A computational model is presented which will help guide and interpret an upcoming series of experiments on nonlinear compressional waves in marine sediments. The model includes propagation physics of nonlinear acoustics augmented with granular Hertzian stress of order 3/2 in the strain rate. The model is a variant of the time domain NPE (McDonald and Kuperman, 1987 supplemented with a causal algorithm for frequency-linear attenuation. When attenuation is absent, the model equations are used to construct analytic solutions for nonlinear plane waves. The results imply that Hertzian stress causes a unique nonlinear behavior near zero stress. A fluid, in contrast, exhibits nonlinear behavior under high stress. A numerical experiment with nominal values for attenuation coefficient implies that in a water saturated Hertzian chain, the nonlinearity near zero stress may be experimentally observable.

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

    Science.gov (United States)

    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

  13. Electric currents couple spatially separated biogeochemical processes in marine sediment

    DEFF Research Database (Denmark)

    Nielsen, Lars Peter; Risgaard-Petersen, Nils; Fossing, Henrik;

    2010-01-01

    Some bacteria are capable of extracellular electron transfer, thereby enabling them to use electron acceptors and donors without direct cell contact 1, 2, 3, 4 . Beyond the micrometre scale, however, no firm evidence has previously existed that spatially segregated biogeochemical processes can be...... coupled by electric currents in nature. Here we provide evidence that electric currents running through defaunated sediment couple oxygen consumption at the sediment surface to oxidation of hydrogen sulphide and organic carbon deep within the sediment. Altering the oxygen concentration in the sea water...... in the sediment was driven by electrons conducted from the anoxic zone. A distinct pH peak in the oxic zone could be explained by electrochemical oxygen reduction, but not by any conventional sets of aerobic sediment processes. We suggest that the electric current was conducted by bacterial nanowires...

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

    Science.gov (United States)

    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 ...

  15. Geochemical records of sediments in the Eastern Gotland Basin - products of sediment dynamics in a not-so-stagnant anoxic basin?

    International Nuclear Information System (INIS)

    Geochemical data from 4 cores taken in the Eastern Gotland Basin of the Central Baltic Sea (68 to 243 m water depth) show that depositional conditions for heavy metals in sediments were similar at all water depths prior to anthropogenic influxes. After the onset of industrialization, the deep anoxic parts of the basin expanded at irregular intervals and the <63 μm fractions of the sediments became characterized by high organic C and heavy-metal accumulation rates. The difference between the enrichment patterns in the basin and on the slope suggests that material enriched in organic matter (and associated trace elements) and in sulphides (and associated trace elements) is preferentially deposited in the basin. The composition of the sediments in the basin therefore reflects the effects of lateral transport of the sediment, which enriches organic C in the deepest part of the basin and of anoxia in the deep water of the basin, where metal sulphides are formed. Previous estimates of the timing of the onset of industrial pollution in the Central Baltic may have been in error because these new data suggest that this began in the Eastern Gotland Basin in about 1870. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  16. Archaeal remains dominate marine organic matter from the early Albian oceanic anoxic event 1b

    DEFF Research Database (Denmark)

    Kuypers, M.M.M.; Blokker, P.; Hopmans, E.C.;

    2002-01-01

    The sources for both soluble and insoluble organic matter of the early Albian (∼112 Myr) oceanic anoxic event (OAE) 1b black shales of the Ocean Drilling Program (ODP) site 1049C (North Atlantic Ocean off the coast of Florida) and the Ravel section of the Southeast France Basin (SEFB) were...... C/C ratios was used to estimate that up to ∼40% of the organic matter of the SEFB and up to ∼80% of the organic matter of ODP site 1049C preserved in the black shales is derived from archaea. Furthermore, it is shown that, even though there are apparent similarities (high organic carbon (OC) content......, distinct lamination, C-enrichment of OC) between the black shales of OAE1b and the Cenomanian/Turonian (∼94 Myr) OAE, the origin of the organic matter (archaeal versus phytoplanktonic) and causes for C-enrichment of OC are completely different. © 2002 Elsevier Science B.V. All rights reserved....

  17. Plutonium behavior during the early diagenesis of marine sediments: applications to two marine environments labelled by radionuclides released from reprocessing plants

    International Nuclear Information System (INIS)

    The plutonium released into the English Channel and the Irish Sea by nuclear fuel reprocessing plants is mainly associated to sediments. Nevertheless, this association is partially reversible. This work combines a field study, carried out on the Cumbrian mud patch and the Esk estuary (Eastern Irish Sea), and laboratory experiments performed on carbonaceous coarse-grained sediments collected in the Central Channel. It presents new data on the plutonium solid partition in sediments and suggests realistic scenarios for describing its release from sediments to the water column. The role of reactive sulphides acting as temporary sink phases is shown in anoxic sediments; those sulphides are liable to release dissolved plutonium upon their oxidation. The plutonium is also bound to carbonates within the carbonaceous matrix and as carbonate surface complexes. Conceptual schemes of the behaviour of the plutonium in marine sediments are proposed; they highlight the strong remobilization potential of plutonium from marine sediments to the interstitial water. Its plutonium content can be injected into the overlying water column. (author)

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

    Science.gov (United States)

    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

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

    International Nuclear Information System (INIS)

    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. - Natural attenuation of PAHs under anaerobic conditions is exceedingly slow

  20. Anoxic sediments off Central Peru record interannual to multidecadal changes of climate and upwelling ecosystem during the last two centuries

    Directory of Open Access Journals (Sweden)

    D. Gutiérrez

    2006-01-01

    illite in layers including large El Niño events (1982-1983, 1986-1987 and 1997-1998, with the largest peak during the 1997-1998 episode. These results confirm that anoxic sediments off Pisco are suitable archives to investigate interannual and decadal changes in oceanographic conditions and climate of the northern Humboldt upwelling system.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  3. Cable Bacteria in Freshwater Sediments

    OpenAIRE

    Risgaard-Petersen, Nils; Kristiansen, Michael; Frederiksen, Rasmus B.; Dittmer, Anders Lindequist; Bjerg, Jesper Tataru; Trojan, Daniela; Schreiber, Lars; Damgaard, Lars Riis; Schramm, Andreas; Nielsen, Lars Peter

    2015-01-01

    In marine sediments cathodic oxygen reduction at the sediment surface can be coupled to anodic sulfide oxidation in deeper anoxic layers through electrical currents mediated by filamentous, multicellular bacteria of the Desulfobulbaceae family, the so-called cable bacteria. Until now, cable bacteria have only been reported from marine environments. In this study, we demonstrate that cable bacteria also occur in freshwater sediments. In a first step, homogenized sediment collected from the fre...

  4. Inhibition of mercury methylation in anoxic freshwater sediment by group VI anions

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.; Miller, G.C. [Univ. of Nevada, Reno, NV (United States). Dept. of Environmental and Resource Sciences; Bonzongo, J.C.J.; Lyons, W.B. [Univ. of Alabama, Tuscaloosa, AL (United States). Dept. of Geology

    1997-08-01

    The addition of group VI anions to sediment slurries resulted in the inhibition of the rate of mercury (Hg) methylation. The ranking of inhibition is as follows: tellurate (TeO{sub 4}{sup 2{minus}}) > selenate (SeO{sub 4}{sup 2{minus}}) > molybdate (MoO{sub 4}{sup 2{minus}}) > tungstate (WO{sub 4}{sup 2{minus}}). In sediment slurries treated with TeO{sub 4}{sup 2{minus}} and Se{sub 4}{sup 2{minus}}, methylmercury (MeHg) formation was significantly inhibited (p < 0.05) at the concentrations >50 nM of TeO{sub 4}{sup 2{minus}} and >270 nM of SeO{sub 4}{sup 2{minus}}, while the significant inhibition (p < 0.05) of Hg-methylation by MoO{sub 4}{sup 2{minus}} and WO{sub 4}{sup 2{minus}} was observed in slurries spiked at final concentrations {le}100 {micro}M and {le}700 {micro}M, respectively. Increasing the sulfate (SO{sub 4}{sup 2{minus}}) concentration while using fixed concentrations of inhibitors led to the partial reestablishment of some MeHg production in WO{sub 4}{sup 2{minus}}-treated slurries, whereas, no such significant change was noticed in sediment slurries treated with MoO{sub 4}{sup 2{minus}} and TeO{sub 4}{sup 2{minus}}. These observations suggested that WO{sub 4}{sup 2{minus}} inhibits Hg methylation by a competitive mechanism, while MoO{sub 4}{sup 2{minus}} and TeO{sub 4}{sup 2{minus}} are noncompetitive inhibitors. Selenate and SO{sub 4}{sup 2{minus}} showed a qualitatively similar effect on Hg methylation at concentrations tested, in that each showed stimulation at low concentrations and inhibition at high concentrations. The depression of MeHg formation by group VI anions was not accompanied by an inhibition of general microbial activity, suggesting that only particular microorganisms, such as sulfate-reducing bacteria, are responsible for Hg methylation.

  5. 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

    Science.gov (United States)

    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

  6. Bioavailability of sediment-bound contaminants to marine organisms

    Energy Technology Data Exchange (ETDEWEB)

    Brown, B. [Battelle/Marine Sciences Lab., Sequim, WA (United States)]|[Colby Coll., Waterville, ME (United States); Neff, J. [Battelle/Marine Sciences Lab., Sequim, WA (United States)]|[Battelle Ocean Sciences, Duxbury, MA (United States)

    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.

  7. Paleoclimatic and paleoceanographic studies of estuarine and marine sediments using strontium isotopes

    International Nuclear Information System (INIS)

    Strontium isotopic ratio (87Sr/86Sr) measurements in fossil carbonates and phosphates are used to evaluate paleoceanographic and paleoclimatic environments in Quaternary, Pliocene-Pleistocene, and mid-Cretaceous estuarine and marine sediments. The use of 87Sr/86Sr measurements as an estuarine paleosalinity and paleoclimatic indicator is developed and applied to San Francisco Bay. 87Sr/86Sr measurements of foraminifer and molluscan fossils contained in estuarine sediments of late Pleistocene (ca 115 to 125 ka) and late Holocene (4.5 ka) age show cyclic variations indicating that salinity fluctuated with periods of several hundred years, probably reflecting wet-dry cycles associated with fluctuations in solar irradiance caused by sunspot cycles. The average salinity in San Pablo and Richardson bays was significantly lower (by 6 to 8%) over much of the past 4.5 ka than at present, reflecting a combination of decreased freshwater inflow at present associated with water diversion and wetter climatic conditions prior to 2000 years ago. Salinity data are converted to river discharge using salinity-delta flow relations derived from historical records for San Francisco Bay. The data indicate that annual freshwater inflow was at least twice the modern pre-diversion average between 2.5 and 3.0 Ka; this time period is also identified as one of wetter climatic conditions by lake level and treeline records from the Sierra Nevada. Strontium isotopic measurements of marine carbonate and fish teeth to middle Cretaceous age are used to increase the resolution of the existing seawater Sr isotope versus time curve and to assess models for global oceanic anoxic events. The new data using fish teeth show less scatter and variability than previous data. Negative excursions in the 87Sr/86Sr ratio of 7-14 parts in 10-5 during Aptian anoxic events suggest a link between increased submarine volcanism and oceanic anoxia

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

    Science.gov (United States)

    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.

  9. Factors Effecting Adsorption of 137 Cs in Marine Sediment Samples in Marine Sediment Samples from the Upper Gulf of Thailand

    International Nuclear Information System (INIS)

    Contamination of 137Cs in sediment is a far more serious problem than in water because sediment is a main transport factor of 137Cs to the aquatic environmental. Most of 137Cs in water could be accumulated in sediment which has direct effect to benthos. This study focused on factors effecting the adsorption of 137Cs in marine sediment samples collected from four different estuary sites to assess the transfer direction of 137Cs from water to sediment that the study method by treat 137Cs into seawater and mixed with different sediment samples for 4 days. The result indicated that properties of marine sediment (cation exchange capacity (CEC), organic matter, clay content, texture, type of clay mineral and size of soil particle) had effects on 137Cs adsorption. CEC and clay content correlated positively with the accumulation of 137Cs in the marine sediment samples. On the other hand, organic matter in sediment correlated negatively with the accumulation of 137Cs in samples. The study of environmental effects (pH and potassium) found that the 137Cs adsorption decreased when concentration of potassium increased. The pH effect is still unclear in this study because the differentiation of pH levels (6, 7, 8.3) did not have effects on 137Cs adsorption in the samples.

  10. Plutonium behavior during the early diagenesis of marine sediments: applications to two marine environments labelled by radionuclides released from reprocessing plants; Etude du comportement du plutonium au cours de la diagenese precoce des sediments marins: applications a deux environnements marins marques par les rejets issus d'usines de retraitement de combustibles uses

    Energy Technology Data Exchange (ETDEWEB)

    Gouzy, A

    2004-12-15

    The plutonium released into the English Channel and the Irish Sea by nuclear fuel reprocessing plants is mainly associated to sediments. Nevertheless, this association is partially reversible. This work combines a field study, carried out on the Cumbrian mud patch and the Esk estuary (Eastern Irish Sea), and laboratory experiments performed on carbonaceous coarse-grained sediments collected in the Central Channel. It presents new data on the plutonium solid partition in sediments and suggests realistic scenarios for describing its release from sediments to the water column. The role of reactive sulphides acting as temporary sink phases is shown in anoxic sediments; those sulphides are liable to release dissolved plutonium upon their oxidation. The plutonium is also bound to carbonates within the carbonaceous matrix and as carbonate surface complexes. Conceptual schemes of the behaviour of the plutonium in marine sediments are proposed; they highlight the strong remobilization potential of plutonium from marine sediments to the interstitial water. Its plutonium content can be injected into the overlying water column. (author)

  11. Biodegradation of petroleum in marine seep sediments

    OpenAIRE

    Mishra, Sonakshi

    2016-01-01

    This study presented for the first time the use of intact sediment cores in a continuous sediment-oil-flow-through (SOFT) system for investigating the degradation of petroleum under a simulated petroleum seepage.The biogeochemical response of sediments from hydrocarbon adapted sites like the Caspian Sea, North Alex Mud Volcano in the Eastern Mediterranean, the Santa Barbara Channel and non-adapted site like the Eckernfoerde Bay in the Baltic Sea to petroleum seepage was investigated and compa...

  12. Sulfate reduction and methanogenesis in marine sediments

    Science.gov (United States)

    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.

  13. Measuring biogenic silica in marine sediments and suspended matter

    Science.gov (United States)

    DeMaster, David J.

    Measuring the biogenic silica content of marine sediments and suspended matter is essential for a variety of geochemical, biological, and sedimentological studies. Biota forming siliceous skeletal material account for as much as one third of the primary productivity in the ocean [Lisitzin, 1972] and a significant portion (2 to 70% by weight) of open-ocean sediments. Biogenic silica measurements reveal important information concerning the bulk chemistry of suspended material or sediment and are essential in any type of silica flux study in the water column or seabed. Analyses of this biogenic phase in marine plankton are useful in characterizing the basic types of biota present and in comparing the distributions of particulate and dissolved silicate when evaluating nutrient dynamics [Nelson and Smith, 1986]. In the marine environment, diatoms, radiolaria, sponges, and silicoflagellates are the common types of siliceous biota.

  14. Reburial of fossil organic carbon in marine sediments

    OpenAIRE

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

    2004-01-01

    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. How...

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

    Science.gov (United States)

    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

  16. Radionuclides in marine sediments - Distribution and processes

    International Nuclear Information System (INIS)

    The NO-1 part of EKO-1 involved both laboratory and field studies. The laboratory studies have been discribed earlier in this report. The following is a summary of the field studies. At station 26 (Norwegian Sea) the sediments seem to be influenced by radiocesium from the Chernobyl accident. This may be due to direct fallout deposition to the sea surface and followed by a rapid sinking and sedimentation. At station 16 (North Sea) some influence from Sellafield plutonium is suggested, as the plutonium ratio is significantly higher (0.07-0.09) than would be expected from global fallout (0.03). Sedimentation rates based on analysis of 210Pb or 210Po varied between 0.03 cm/year - 0.25 cm/year. A surprisingly low sedimentation rate was found in the tenisey Bay (0.05 cm/year). It is possible that the dating method is less suited in this area, due to the long winter ice cover. In general, the rough estimates on Kd values for 137Cs obtained empirically are highter than Kd values obtained from the alboratory studies. This may be due to the fact that the 2 cm surface sediment in most cases has accumulated over many years, carrying contamination from the early eighties when levels of 137Cs in the sea water were higher. The 137Cs in the sediments it now fixed, or being remobilized only very slowly. Burial of the contamination by sedimentation may also make it unavailable for exchange with free water masses. (EHS)

  17. Oceanographic Survey. 3. Radiological survey of marine sediments

    International Nuclear Information System (INIS)

    A part of the outcomes of radiological survey of marine sediments were reported and countermeasures for some problems in the survey were discussed. A modified Smith-McIntyre's collector in a column shape was used for sampling of marine sediments and its structure was outlined in this report. The survey was made at inner sides of bay, shallow areas of coast up to the depth of 200 m, offshore areas of sea and open sea areas. There were two problems for analysis of radionuclides in marine sediments. The first was the age of marine sediment layer to analyze. In the survey points at which amounts of sedimentation were comparatively large, analysis was made based on the vertical distribution of Pb-210. The second was the factor(s) affecting the concentration of radionuclides in marine sediments. The accumulation amounts of Pb-210 and Cs-137 were determined for the samples collected in the Sagami Bay and a close correlation was found between the two accumulations, suggesting that the accumulation of Pb-210 is available for the factor to assess the pollution due to artificial radionuclides. The accumulations of Cs-137 and Bi-207 were compared among five points; a north-east (A), a center (B) and a south-west (C) region of Pacific, the Japan Sea (D) and the Uraga Channel - the Sagami Bay (E). The amount of accumulation for Cs-137 was the largest at (E) followed by (D) and the accumulation of Bi-207 was also greatest at (E). However, the reason of those high levels at (E) has not been elucidated. (M.N.)

  18. Measurement of uranium and thorium in marine sediments

    International Nuclear Information System (INIS)

    Lakes, oceans and seas accumulate sediments. These sediments constitute a file of the last environmental conditions going up in some cases to thousands of years. In our study, we consulted this file by analyzing radioisotopes of Uranium and Thorium that are included in a carrot of marine sediment taken from the south of Mediterranean Sea. When we applied the technique developed by the maritime environment's laboratory of Monaco, we found spectra with bad resolutions. For this reason, the optimization of this protocol appeared necessary. (Author).

  19. Algal and archaeal polyisoprenoids in a recent marine sediment

    DEFF Research Database (Denmark)

    Bian, Liangqiao; Hinrichs, Kai-Uwe; Xie, Tianmin;

    2001-01-01

    Analyses of C-13 contents of individual organic molecules in a marine sediment show that crocetane, 2,6,11,15-tetramethylhexadecane, an isomer of phytane, is produced by microorganisms that use methane as their main source of carbon. The sediments lie at a water depth of 68 m in the Kattegat, the...... strait between Denmark and Sweden. Crocetane appears first 185 cm below the sediment-water interface, in the zone marking the transition from sulfate reduction to methanogenesis. Its delta C-13 value is -90 +/- 10 parts per thousand versus Vienna Pee Dee Belemnite (VPDB). Its structure, which includes...

  20. Partition of iodine (¹²⁹I and ¹²⁷I) isotopes in soils and marine sediments.

    Science.gov (United States)

    Hansen, Violeta; Roos, Per; Aldahan, Ala; Hou, Xiaolin; Possnert, Göran

    2011-12-01

    Natural organic matter, such as humic and fulvic acids and humin, plays a key role in determining the fate and mobility of radioiodine in soil and sediments. The radioisotope ¹²⁹I is continuously produced and released from nuclear fuel reprocessing plants, and as a biophilic element, its environmental mobility is strongly linked to organic matter. Due to its long half-life (15.7 million years), ¹²⁹I builds up in the environment and can be traced since the beginning of the nuclear era in reservoirs such as soils and marine sediments. Nevertheless, partition of the isotope between the different types of organic matter in soil and sediment is rarely explored. Here we present a sequential extraction of ¹²⁹I and ¹²⁷I chemical forms encountered in a Danish soil, a soil reference material (IAEA-375), an anoxic marine sediment from Southern Norway and an oxic sediment from the Barents Sea. The different forms of iodine are related to water soluble, exchangeable, carbonates, oxides as well as iodine bound to humic acid, fulvic acid and to humin and minerals. This is the first study to identify ¹²⁹I in humic and fulvic acid and humin. The results show that 30-56% of the total ¹²⁷I and 42-60% of the total ¹²⁹I are associated with organic matter in soil and sediment samples. At a soil/sediment pH below 5.0-5.5, (¹²⁷I and ¹²⁹I in the organic fraction associate primarily with the humic acid while at soil/sediment pH > 6 ¹²⁹I was mostly found to be bound to fulvic acid. Anoxic conditions seem to increase the mobility and availability of iodine compared to oxic, while subaerial conditions (soils) reduces the availability of water soluble fraction compared to subaqueous (marine) conditions. PMID:21924531

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

    Directory of Open Access Journals (Sweden)

    Carolina eCruz Viggi

    2015-09-01

    Full Text Available 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 1 or 3 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 3 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 1 and 3 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 configurations for field

  2. Meiofauna increases bacterial denitrification in marine sediments.

    Science.gov (United States)

    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 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

  3. Non-lithogenic (autigenic and anthropogenic) uranium enrichments in the coastal marine sediments of the central Gulf of California

    International Nuclear Information System (INIS)

    Full text: Uranium geochemistry in the marine environment is considered as promising for a search of proxies for paleooceanographic reconstructions. High water primary production due to the utilization of the dissolved oxygen for the remineralization of settling organic particles generates suboxic or anoxic conditions in the intermediate oceanic waters favouring to the reduction of U(+6) existing in the sea water as truly dissolved form to U(+4) species, characterized by a low solubility and related high affinity to particles and sediments. To verify the possibilities of U enrichments in the marine sedimentary environment of the eastern sector of the central Gulf of California (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 Rosalia at the sites with a water depths from 265 m to 1030 m and in the Guaymas Basin (water depth 2019 m) ranged from 1.36 ± 0.26 mg/kg (Guaymas Basin) to 9.31 ± 3.03 mg/kg (SR63 core, depth 630 m). To distinguish non-lithogenic U from lithogenic one, the normalization of total U contents to the concentrations of Sc in the samples was used, 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 ± 3.0 % (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 Rosalia in water depth range 3-6 m very high concentrations of total U were found, ranging from 54.2 ± 7.3 mg/kg ( SR4 core) to 110 ± 13 mg/kg (SR2 core) and exceeding not only U average

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

    Science.gov (United States)

    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.

  5. Evaluating Sediment Stability at Offshore Marine Hydrokinetic Energy Facilities

    Science.gov (United States)

    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

  6. Sorption behavior of nonylphenol on marine sediments: Effect of temperature, medium, sediment organic carbon and surfactant

    International Nuclear Information System (INIS)

    Highlights: → NP sorption kinetics accorded with non-linear Ho-McKay pseudo-second-order model. → Kd values showed positive correlation with sediment OC contents. → Medium salinity showed positive correlation with Kd and negative with DOC. → CTAB enhanced NP sorption amount the most while SDBS enhanced the lest. → NP sorption was an exothermic physical and spontaneous entropy-decreasing reaction. - Abstract: The sorption behavior of nonylphenol (NP, a toxic endocrine disruptor) on marine sediments was studied in detail through a series of kinetic and thermodynamic sorption experiments. The results showed that the sorption reaction of NP on marine sediments reached equilibrium in 1.5 h and that it accorded well with the non-linear Ho-McKay pseudo-second-order model. The sorption isotherms of NP on H2O-treated sediments could be well described by the Linear isotherm model, while the sorption isotherm on H2O2-treated sediments could be well fitted with the Freundlich isotherm model. A positive correlation was found between the distribution coefficient (Kd) and the sediment organic carbon contents. The medium salinity showed a positive relation with the Kd and a negative relation with the dissolved organic carbon (DOC). Hexadecyl trimethyl ammonium bromide (CTAB) enhanced the sorption amount of NP the most, while sodium dodecylbenzenesulfonate (SDBS) enhanced it the least. The sorption reaction of NP on marine sediments was a spontaneous, physical, exothermic and entropy-decreasing process.

  7. Sulfur Isotope Exchange between S-35 Labeled Inorganic Sulfur-Compounds in Anoxic Marine-Sediments

    DEFF Research Database (Denmark)

    FOSSING, H.; THODEANDERSEN, S.; JØRGENSEN, BB

    1992-01-01

    of isotope exchange, specific radioactivities of the reduced sulfur pools were poorly defined and could not be used to calculate their rates of formation. Such isotope exchange reactions between the reduced inorganic sulfur compounds will affect the stable isotope distribution and are expected to decrease...

  8. Dating methods about bulk sediments in marine environment

    International Nuclear Information System (INIS)

    With the development of science and technology progress, the studies about dating methods of sediments become more and more precise. Widely used of so many dating methods have offered reliable scientific evidence for the foundation of accurate chronostratigraphic framework in different region. Considering the difference of sedimentary environment as well as sediment types between inland and submarine, the dating method should be secerned. However, there are few articles which specially introduce the dating methods about bulk sediments in submarine environment. Based on the conclusion and summarized about many dating methods, especially focus on the sediment types and dating range,the conformable isotope dating methods (210Pb, 14C), OSL dating and comparatively dating methods (ie., Oxygen isotope curve, Paleomagnetic) which suitable for the bulk sediments in marine environment are suggested. Dating have an very important function in marine geological studies. In order to enhance the veracity and reliability of the dating data, the proper methods based on sediment types and estimated age range are selected. On the other hand,the progress cross-comparison during different dating methods are given. (authors)

  9. Radionuclide impact on sediments and algae from Black sea marine ecosystems

    International Nuclear Information System (INIS)

    Radionuclide metals are the major part of anthropogenic fallout pollutants in the Black Sea marine ecosystems. The complex analysis of pollutant concentrations is a major concern for modern ecology in obtaining reliable information about the type and quantities of substances entering the marine environment. Marine macroalgae are important factor for nuclides accumulation in marine ecosystems. The ecological conditions at the Black Sea littoral zone vary depending on the location and depth. The seasonal change in macrophytic species is determined by the season, temperature and light regime. Some algae species are adaptive to contamination but some species react quickly to the environmental changes especially to the chemical contaminants. This paper deals with the problem of transboundary pollution in the Black Sea and the most significant pollution problem has been identified as the eutrophication phenomenon. Oxygen deficiency (hypoxia or anoxia) and mass mortality caused by eutrophication have become a permanent feature in the north-western shelf area where anoxic zones have expanded from covering 3500 km2 in 1973 to 40,000 km2 in 1990. The data for technogenic (mainly 137Cs) and natural radionuclides were determined in the sediment samples collected along the Bulgarian Black Sea coast. The measured levels correspond to those cited in the literature for background levels, showing no additional anthropogenic contamination. In sand and sandy sediments Cs content does not change greatly while the process of 137Cs accumulation is observed in slime and silt sediments. The data show that the 238U and 226Ra values are close at most of the locations. 226Ra /238U activity ratio (mean value) for sand and sandy sediments is in the range 0.55 - 0.85, meaning 226Ra deficit while the values for 226Ra /238U ratios in slime and silt sediments are close to the equilibrium. The obtained data show that radionuclide concentrations strongly depend on the sediment nature. Results for

  10. The geochemistry and mobility of the lanthanides in marine sediments

    International Nuclear Information System (INIS)

    A study has been made to evaluate lanthanide mobility in sediments directly by measuring concentrations of 10 lanthanide elements in sediments and pore waters. Due to the very low concentrations of the lanthanides in sea water relative to marine sediments, evidence of lanthanide mobilization is usually difficult to detect from studies of solid-phase geochemistry. Results show that the lanthanides can be extremely mobile. Concentrations in pore waters up to 100 times sea water concentrations have been measured. The conclusions are tentative but the present data suggest that the lanthanides are mobilized during oxidation of organic-rich sediments and are relocated in part in association with secondary Fe-rich phases. The behaviour of Ce is, predictably, somewhat different from the other lanthanides and may be more mobile as a consequence of its redox chemistry. (author)

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

    Science.gov (United States)

    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

  12. Remobilization of Iodine in Marine Sediments During Early Diagenesis

    Institute of Scientific and Technical Information of China (English)

    程先豪

    1993-01-01

    Based on the sedimentary geochemical studies of the Antarctic Ocean and the various geochemical parameters available,this paper deals with the process of emobilization of iodine in marine sediments during early diagenesis.The results showed that the process is not always controlled completely by organic matter as was expected previously.On average the adsorption and oxide phases of iodine account respectively for 23% and 32% of the total in continental-shelf and hemipelagic surficial sediments.Chemical analysis has revealed that the upward diffusion flux and redox conditions would play an important role in the concentration of iodine in the surface sediments.And the species of iodine in the surfial sediments characteristic of high I/Corg ratios would bepredominated by the oxide and adsorption phases.As experimentally evidenced,it is the early diagenetic remoibilization of iodine associated with the oxide and adsorption phases that led to the decrease of I/Corg with increasing depth.Calculations suggested that the diffusion flux of iodine from the deep parts of te sedimentary columum upwards is on the same order of magnitude as the deposition flux of it from sea water.This may be one of the important factors leading to the depletion of iodine in sedimentary rocks.On the basis of the above discussion and calculations the author has proposed a model for the remobilization of iodine in marine sediments during early diagenesis.

  13. Gamma activation analysis of marine sediments at Havana Bay, Cuba

    International Nuclear Information System (INIS)

    Twenty six elements was studied preliminary in the superficial sediments of Havana Bay using gamma activation analysis by the electron accelerator microtron MT-25 at the Flerov Laboratory of Nuclear Reactions, JINR. Samples from five zones of Havana Bay including the three coves were analyzed. The obtained results show a close relation between the concentration levels of the studied elements and the pollution sources. Some elements (As, Ba, Ni, Pb, Cu, Zn, Fe, Cr, Mn) have high concentration levels compared to the values for other environmental marine sediments reported in the literature. (author)

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

    Science.gov (United States)

    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. Influence of macrobenthos on chemical diagenesis of marine sediments

    Energy Technology Data Exchange (ETDEWEB)

    Aller, R.C.

    1977-05-01

    Diagenetic reactions involving the decomposition of organic matter and the dissolution, mobilization, and reprecipitation of metals sensitive to oxidation-reduction reactions, are most intense and rapid in the upper 1 m and especially the upper 10 cm of marine sediment. It is in this upper zone where most benthic organisms live and interact with sediments and where exchange rates of dissolved and particulate material between sediment and overlying water are largely determined. In Long Island Sound, U.S.A., both spatial and temporal trends in sediment chemistry and the flux of material out of the bottom demonstrate the control of diagenesis by bottom fauna. /sup 234/Th//sup 238/U disequilibrium studies demonstrate that particle reworking rates near the sediment-water interface vary both temporally and spatially in the Sound. The most rapid reworking occurs in protobranch-inhabited bottom areas as do the highest /sup 234/Th inventories. Excess /sup 234/Th profiles in the sediment allow determination of the rates of selected diagenetic reactions, such as Mn/sup + +/ production, near the sediment surface. Both the /sup 234/Th disequilibrium and flux measurements indicate that intra-estuarine redistribution of metals continually takes place.

  16. Oceanographic Survey. 3. Radiological survey of marine environment in Ibaraki Prefecture: marine sediment survey

    International Nuclear Information System (INIS)

    Radioactivity in marine environment of Ibaraki Prefecture has been monitored since 1965. This report briefly describes the radiological survey data of marine sediments. The concentrations of radionuclides in marine water were determined yearly 4 times for 3H and twice for 54Mn, 60Co, 90Sr, 95Zr, 95Nb, 106Ru, 137Cs and 144Ce. The concentrations of 90Sr, 137Cs and 239+240Pu were hardly changed and those of 90Sr and 137Cs were near the limit of identification. The annual excretion of radionuclides from major nuclear plants in Ibaraki Prefecture including JAERI (Tokai and Oarai), Japan Atomic Power Co., etc. were determined for 3H, 14C, 90Sr, 137Cs, 60Co, 129I and 239+240Pu. Based on the results, dose equivalent for the intake of marine animals and algae was estimated to be as low as 0-4.4 μSv. This level was extremely lower than the limit of annual dose equivalent; 1000 μSv and it was kept nearly constant if the operators of those facilities were not discontinued for a long. To elucidate the factors related to the transfer of radionuclides into marine sediments, the depth dose distribution in marine sediments were investigated as well as the relation between radionuclide level and granular size. An elevation of 137Cs level was found for the sediments composed of fine granules, which were rich in the sediments of offshore region. The 239+240Pu level was positively correlated to the content of organic compounds in the sea. (M.N.)

  17. Magnetic mineral study of Holocene marine sediments from the Alfonso Basin, Gulf of California - implications for depositional environment and sediment sources

    Directory of Open Access Journals (Sweden)

    L. Pérez Cruz

    2009-07-01

    Full Text Available Results of a rock magnetic study of marine sediments from the Alfonso Basin, Bay of La Paz are used to investigate sediment sources and depositional environment in the southern Gulf of California during the Holocene. Radiocarbon dating provides stratigraphic control, with age for the core bottom sediments of 7597-7831 cal. yr B.P. Magnetic signal is dominated by fine-grained titanomagnetites, derived from the silicic volcanic units surrounding the Bay of La Paz. Magnetic mineralogy is relatively homogenous as seen in bulk magnetic properties of low-field susceptibility, remanent intensity and coercivity. Magnetic hysteresis loops show strong variable paramagnetic components; after paramagnetic correction loops show saturation at low fields and high saturation magnetization values. Plots of hysteresis parameter ratios for domain state show that samples group in the pseudo-single domain field, with mixtures of single and multi-domain particles. Magnetic susceptibility log shows relatively high frequency dependence factors, particularly for the Middle Holocene, suggesting contribution of fine-grained superparamagnetic minerals related to eolian deposition. The well-preserved laminated sequence indicates predominant anoxic conditions in the basin floor. Depositional environment had a dominant supply of pluvial detrital sediments and eolian fimaterial with less abundant biogenic input.

  18. Marine sediments in Disko Trough reveal meltwater-influenced sedimentation during ice-stream retreat

    Science.gov (United States)

    Hogan, Kelly A.; Cofaigh, Colm Ó.; Jennings, Anne E.; Dowdeswell, Julian A.

    2015-04-01

    Marine geophysical data from middle and outer Disko Trough, West Greenland reveal thick (more than ten metres) acoustically-laminated, fine-grained sediments between subglacial tills at their base and post-glacial marine sediments at the seafloor. These sediments are interpreted as a transitional facies deposited as ice retreated from the trough during deglaciation. New sediment-core records indicate that these units were likely deposited by meltwater plumes emanating from a nearby grounded-ice margin, probably during stillstands in ice retreat. The retreat of ice in the trough may have been stabilised at a narrowing in DiskoTrough on the mid-shelf, as well as at the basalt escarpment south of Disko Island. Such thicknesses of deglacial or "transitional" glacimarine sediments are relatively unusual on high-latitude continental shelves and indicate a significant meltwater production in central West Greenland during deglaciation. This is consistent with the seafloor landforms in the inner and middle parts of the trough that include channels and moats around bedrock protrusions that look to have been eroded by water. IRD counts from the cores indicate that iceberg rafting also occurred during this transitional phase but that this signal was diluted by the fine-grained transitional sediments. Once ice had withdrawn from the area and sedimentation was hemipelagic in nature the IRD signal was less diluted.

  19. Biogenic methane potential of marine sediments. Application of chemical thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Arning, E.T.; Schulz, H.M. [Helmholtz Centre Potsdam GFZ, Potsdam (Germany); Berk, W. van [Technical Univ. of Clausthal (Germany). Dept. of Hydrogeology

    2013-08-01

    Accumulations of biogenic methane-dominated gas are widespread and occur in a variety of depositional settings and rock types. However, the potential of biogenic methane remains underexplored. This is mainly due to the fact that quantitative assessments applying numerical modeling techniques for exploration purposes are generally lacking to date. Biogenic methane formation starts in relatively shallow marine sediments below the sulfate reduction zone. When sulfate is exhausted, methanogenesis via the CO{sub 2} reduction pathway is often the dominant biogenic methane formation process in marine sediments (Claypool and Kaplan, 1974). The process can be simplified by the reaction: 2CH{sub 2}O + Ca{sup 2+} + H{sub 2}O {yields} CH{sub 4} + CaCO{sub 3} + 2H{sup +}. The products of early diagenetic reactions initiate coupled equilibrium reactions that induce a new state of chemical equilibrium among minerals, pore water and gas. The driving force of the complex biogeochemical reactions in sedimentary environments during early diagenesis is the irreversible redox-conversion of organic matter. Early diagenetic formation of biogenic methane shortly after deposition ('early diagenesis') was retraced using PHREEQC computer code that is applied to calculate homogenous and heterogeneous mass-action equations in combination with one-dimensional diffusion driven transport (Parkhurst and Appelo, 1999). Our modeling approach incorporates interdependent diagenetic reactions evolving into a diffusive multi-component and multiphase system by means of thermodynamic equilibrium calculations of species distribution (Arning et al., 2011, 2012, 2013). Reaction kinetics of organic carbon conversion is integrated into the set of equilibrium reactions by defining type and amount of converted organic matter in a certain time step. It is the aim (1) to calculate quantitatively thermodynamic equilibrium conditions (composition of pore water, mineral phase and gas phase assemblage) in

  20. Distribution of actinomycetes in near-shore tropical marine sediments.

    OpenAIRE

    Jensen, P R; Dwight, R; Fenical, W.

    1991-01-01

    Actinomycetes were isolated from near-shore marine sediments collected at 15 island locations throughout the Bahamas. A total of 289 actinomycete colonies were observed, and all but 6 could be assigned to the suprageneric groups actinoplanetes and streptomycetes. A bimodal distribution in the actinomycete population in relation to depth was recorded, with the maximum numbers occurring in the shallow and deep sampling sites. This distribution can be accounted for by a rapid decrease in strepto...

  1. Methylotrophic methanogenesis and potential methylated substrates in marine sediment

    OpenAIRE

    Zhuang, Guangchao

    2014-01-01

    Methane is the simplest hydrocarbon and a potent greenhouse gas that plays important roles in atmospheric chemistry, the global carbon cycle, and the formation of gas hydrates in marine sediment. Microbial production of methane is the terminal step during the degradation of organic matter. It is generally thought that methane is predominantly produced from hydrogenotrophic and acetoclastic methanogenesis, while methylotrophic methanogenesis and its relative importance for methane production i...

  2. The bioremediation potential of marine sandy sediment microbiota

    OpenAIRE

    Dan Răzvan POPOVICIU

    2012-01-01

    The natural microbiota from marine sandy sediments on the Romanian sea coast was tested for resilience in case of hydrocarbon contamination, for estimating the number of (culturable) hydrocarbon and lipid oil-degrading microorganisms and for determining the influence of inorganic nitrate and phosphate nutrients on hydrocarbon spill bioremediation process, by microcosm experiments.Results show that hydrocarbon contamination affects the bacteriobenthos both in terms of cell numbers and composit...

  3. A novel approach to the sequential extraction of plutonium from oxic and anoxic sediment using sodium citrate to inhibit post-extraction resorption

    International Nuclear Information System (INIS)

    Sequential extraction has been used extensively to study the solid partitioning of radionuclides in soils and sediments. A difficulty with sequential extraction is that radionuclides released by a particular extractant can be resorbed and artificially redistributed amongst the remaining solid phases. Here, we describe experiments (on selected model phase and natural materials), which were designed to determine whether the inclusion of a chelating agent (sodium citrate) in an established sequential extraction protocol (a) inhibits post-extraction resorption of plutonium, (b) increases non-targeted dissolution of sediment phases, and (c) gives rise to unwanted ligand competition for plutonium. The results clearly demonstrate the capacity of citrate to inhibit the resorption of plutonium from the various extractants, and confirm that there is no discernible increase in non-targeted phase dissolution, but indicate significant ligand competition with the carbonate phase. The merits of using citrate are discussed and an optimised sequential extraction protocol that includes citrate is proposed. Finally, the protocol is applied to oxic and anoxic sediments sampled in the NE Irish Sea and the Roads of Cherbourg, and it is shown that the bulk of the plutonium on these sediments is associated with the more labile geochemical fractions

  4. Monitoring of biofilm growth in marine sediment by metal electrodes

    Science.gov (United States)

    Cristiani, P.; Guandalini, R.; Del Negro, P.; Cataletto, B.

    2009-04-01

    Electrochemical monitoring of biofilm growing in marine sediments is evaluating in laboratory experiments, still in progress. The interesting preliminary results obtained during six month experiments are presented in this paper. A concept of electrochemically active bacteria has recently pointed out by several studies, showing that bacteria forming biofilms on conductive materials can achieve a direct electrochemical connection with the substrate using it as electron exchanger, also without the aid of additional mediators [1]. The electric current generated by bacteria is more than enough as signal for bio-sensors. Thanks to the developing of bio-sensors based on electrochemical probes and able to monitoring the biofilm growth on metal surfaces, this "bio-electricity" has been already exploited with success for the biofilm monitoring in industrial equipment exposed to natural waters [2]. The same, very simple, electrochemical biofilm probes, in which electrical signal is proportional to biofilm growth, already successfully used for aerobic environments, have been here tested in the anaerobic environment of marine sediments. A laboratory microcosm has been prepared by filling a large polycarbonate cylinder about one-third full with organic-rich coastal marine sediment collected in the Gulf of Trieste (Northern Adriatic Sea). The sediment was packed tightly in the container to avoid entrapping air and then covered with O2 depleted seawater. Three identical electrochemical sensors were buried in the sediment of microcosm. The cylinder was placed in the dark under controlled temperature and anaerobic conditions. During the six months of monitoring, bacterial communities developing at the water-sediment interface were periodically sampled by inserting a long thin pipette into the column and removing some coloured mud or water. The microrganisms were used to inoculate enriched media and to extract bulk DNA. The results pointed out the possibility of set up simple device

  5. Demethylation and cleavage of dimethylsulfoniopropionate in marine intertidal sediments

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  9. Diversity and novelty of actinobacteria in Arctic marine sediments.

    Science.gov (United States)

    Zhang, Gaiyun; Cao, Tingfeng; Ying, Jianxi; Yang, Yanliu; Ma, Lingqi

    2014-04-01

    The actinobacterial diversity of Arctic marine sediments was investigated using culture-dependent and culture-independent approaches. A total of 152 strains were isolated from seven different media; 18 isolates were selected for phylogenetic analysis on the basis of their 16S rRNA gene sequences. Results showed that the 18 isolates belonged to a potential novel genus and 10 known genera including Actinotalea, Arthrobacter, Brachybacterium, Brevibacterium, Kocuria, Kytococcus, Microbacterium, Micrococcus, Mycobacterium, and Pseudonocardia. Subsequently, 172 rDNA clones were selected by restriction fragment length polymorphism analysis from 692 positive clones within four actinobacteria-specific 16S rDNA libraries of Arctic marine sediments, and then these 172 clones were sequenced. In total, 67 phylotypes were clustered in 11 known genera of actinobacteria including Agrococcus, Cellulomonas, Demequina, Iamia, Ilumatobacter, Janibacter, Kocuria, Microbacterium, Phycicoccus, Propionibacterium, and Pseudonocardia, along with other, unidentified actinobacterial clones. Based on the detection of a substantial number of uncultured phylotypes showing low BLAST identities (<95 %), this study confirms that Arctic marine environments harbour highly diverse actinobacterial communities, many of which appear to be novel, uncultured species. PMID:24519808

  10. Neutron activation analysis studies of marine biological species and related marine sediments

    International Nuclear Information System (INIS)

    To assess the effects, if any, of elemental pollution of the Pacific Ocean from the major Southern California sewage outfalls, samples of ocean sediments were obtained and specimens of Dover Sole were caught in a number of locations. Liver tissue samples from Dover Sole specimens were analyzed for 12 elements and sediment samples for 4 elements. Although a number of the elements were highly concentrated in the surface sediments in the heavily-polluted areas, the Dover Sole showed no evidence of picking up any of the 12 elements from these polluted sediments. Sediment profiles, versus depth, (0-34 cm) were also determined for As, Sb, Se, and Hg. Stemming partly from the results of the NSF Baseline Study, the Southern California Coastal Water Research Project (SCCWRP) became interested in a more intensive multi-element study of marine biological species and ocean sediments off the coast of Southern California. The purpose of this study was to assess the effects, if any, of a number of selected elements of interest being discharged into the Pacific Ocean from the principal sewage outfalls in the Southern California (Los Angeles) area upon marine biological species. The 12 elements selected for study were Cr, Fe, Co, Cu, Zn, As, Se, Mo, Ag, Cd, Sb, and Hg. Since a number of these elements were not amenable to purely instrumental NAA measurements, a suitable post-irradiation radiochemical separation procedure was devised, thoroughly tested, and then applied to 39 samples of liver tissue from specimens of Dover Sole caught in non-polluted, slightly-polluted, fairly-polluted, and heavily-polluted areas along the coast. A number of surface sediment samples from these same locations were also analyzed, by both instrumental and radiochemical NAA. In the following sections, the samples analyzed are cited, the procedures developed and employed are described, the results obtained are presented, and the conclusions reached are discussed

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

    OpenAIRE

    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...

  12. Methodical problems of thermoluminescence dating of holocene eolian and marine sediments

    International Nuclear Information System (INIS)

    Methodological problems of thermoluminescence dating of eolian and marine sediments are described. On the basis of studies performed it is shown that K-feldspars are perspective paleodosemeters for TL-dating of sediments of the above-mentioned genesis. TL-dating results of the Holocene eolian sediments from Estonia and the Middle Pleistocene marine, sediments from Arkhangelsk region with reconstructed residual lightsum are presented. The results are in good agreement with those obtained by other dating methods and geological models

  13. Role of Methanogens and Other Bacteria in Degradation of Dimethyl Sulfide and Methanethiol in Anoxic Freshwater Sediments

    OpenAIRE

    Bart P. Lomans; Op den Camp, Huub J.M.; Pol, Arjan; van der Drift, Chris; Vogels, Godfried D.

    1999-01-01

    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 μmol of DMS was stoichiometrically converted into 112 μmol of methane. T...

  14. Synchronous negative carbon isotope shifts in marine and terrestrial biomarkers at the onset of the early Aptian oceanic anoxic event 1a: Evidence for the release of 13C-depleted carbon into the atmosphere

    Science.gov (United States)

    van Breugel, Yvonne; Schouten, Stefan; Tsikos, Harilaos; Erba, Elisabetta; Price, Gregory D.; Sinninghe Damsté, Jaap S.

    2007-03-01

    A common feature of records of the early Aptian oceanic anoxic event (OAE) 1a is the sharp negative δ13C excursion displayed in both carbonate and organic matter at the onset of this event. A synchronous negative δ13C excursion has also been noted for terrestrial organic matter. This negative excursion has been attributed to either an injection of 13C-depleted light carbon into the atmosphere or, in case of marine sediments, recycling of 13C-depleted CO2. However, most studies were done on separate cores, and no information on the relative timing of the negative spikes in terrestrial versus marine records has been obtained. Here we examine early Aptian core sections from two geographically distal sites (Italy and the mid-Pacific) to elucidate the causes and relative timing of this negative "spike." At both sites, increased organic carbon (Corg) and decreased bulk carbonate contents characterize the interval recording OAE 1a (variously referred to as the "Selli event"). The organic material within the "Selli level" is immature and of autochthonous origin. Measured δ13C values of marine and terrestrial biomarkers largely covary with those of bulk organic carbon, with lowest values recorded at the base of the organic-rich section. By contrast, sediments enveloping the "Selli level" exhibit very low Corg contents, and their extractable Corg is predominantly of allochthonous origin. Hydrous pyrolysis techniques used to obtain an autochthonous, pre-Selli δ13C value for algal-derived pristane from corresponding sample material yielded a negative δ13C shift of up to 4‰. A negative δ13C shift of similar magnitude was also measured for the terrigenous n-alkanes. The results are collectively best explained by means of a massive, syndepositional, rapid input of 13C-depleted carbon into the atmosphere and surface oceans, likely delivered either via methane produced from the dissociation of sedimentary clathrates or perhaps by widespread thermal metamorphism of Corg

  15. Bacterial corrosion in marine sediments: influence of cathodic protection

    International Nuclear Information System (INIS)

    In order to protect offshore structures from marine corrosion, cathodic protection is widely applied via sacrificial anodes (for example zinc or aluminium) or impressed current. In aerated seawater, steel is considered to be protected when a potential of -8050 mV/Cu.CuSO4 is achieved. In many cases, however this potential must be lowered, due to the activity of microorganisms and more specially sulfate-reducing bacteria (SRB). SRB are obligate anaerobes using sulphate as electron acceptor with resultant production of sulphide. Some of them are also able to use hydrogen as energy source, causing cathodic depolarization of steel surfaces. An experiment was performed to analyze the relation between SRB activity and use of different cathodic potentials applied to mild steel samples in marine sediments. Analytical techniques employed included lipid bio-markers and electrochemical methods. Results indicated an evolution of the bacterial community structure both on the steel and in the sediment, as a function of time and potential. The results also show that cathodically produced hydrogen promotes the growth of SRB (author)

  16. Concentration of 60Co by marine organisms through sediments

    International Nuclear Information System (INIS)

    Uptake of 60Co absorbed on sea sands by benthic marine organisms was observed in laboratory experiments, since the radioactive cobalt released from nuclear power plants or other establishments into coastal seawater trends to be absorbed on sea sediments and also various kinds of marine organisms live in bottom sediments. Few kinds of flatfishes (Limanda spp.) and shrimp (Trachypenaeus curvirostris) were reared in aquariums contained seawater and sea sands which were highly contaminated with 60Co previously, and whole body retention and distribution of radioactivity were measured on the organisms taken up from the aquariums occasionally by a scintillation counter. Uptake of 60Co from ingested sea sands was also observed on the flatfishes administrating the contaminated sands orally. Concentration of 60Co by the flatfishes reared in the sands was not significant while the shrimp showed high retention of the radioactivity. The food habit of shrimp which usually feeds on organic detritus with other small benthic organisms is different from that of flatfishes, one of the carnivorous, and considered to bring the difference on the pathway of radionuclides concentration. Assimilation of 60Co via the digestive tract of flatfishes through the sands was estimated as about 10 per cent of the administrated radioactivity. (auth.)

  17. The bioremediation potential of marine sandy sediment microbiota

    Directory of Open Access Journals (Sweden)

    Dan Răzvan POPOVICIU

    2012-11-01

    Full Text Available The natural microbiota from marine sandy sediments on the Romanian sea coast was tested for resilience in case of hydrocarbon contamination, for estimating the number of (culturable hydrocarbon and lipid oil-degrading microorganisms and for determining the influence of inorganic nitrate and phosphate nutrients on hydrocarbon spill bioremediation process, by microcosm experiments.Results show that hydrocarbon contamination affects the bacteriobenthos both in terms of cell numbers and composition. Bacterial numbers showed a rapid decrease (28% in four days, followed by a relatively fast recovery (two weeks. The pollution favoured the increase of Gram-positive bacterial proportion (from around 25% to 33%Sandy sediment microbiota in both sites studied contained microorganisms able to use mineral or lipid oils as sole carbon sources, usually around 103-104/cm3, with variations according to the sediment grain size and substrate used.The biostimulation experiments showed that, in absence of water dynamism (and, implicitly, an efficient oxygenation, the addition of nitrogen and phosphorus can be ineffective and even inhibit the remediation process, probably due to eutrophication.

  18. A method of harvesting gas hydrates from marine sediments

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H.Q.; Brill, J.P.; Sarica, C. [Tulsa Univ., Tulsa, OK (United States). Dept. of Petroleum Engineering

    2008-07-01

    Methane is known to exist in gas hydrates, but low productivity is expected for gas production from gas hydrates in marine sediments because of the shallow depths, low hydrate concentration, low permeability of the gas hydrate stability zone, lack of driving pressure and the slow melting process. This paper presented a newly developed methane harvesting method which aims to overcome technical barriers, maintain cost and energy efficiencies and minimize safety and environmental concerns. The method is based on the concept of capturing the gas released from hydrate dissociation in the sediments. The captured gases can reform hydrates inside and overhead receiver, which once full, can be lifted to shallow warm water for gas collection. This simple and open production system does not require high pressure and does not involve any flow assurance issues. As such, technical difficulties, safety issues and environmental concerns are minimized. The proposed gas harvesting method makes the best use of the nature of hydrates and the subsea pressure and temperature profiles. It combines many new concepts, including electrically adding heat inside the hydrate rich sediments to release gas, using an overhead receiver to capture the gas, allowing the gas to reform hydrates again in the overhead receiver, and lifting produced hydrates to warm water where it can be released and collected. It was concluded that this newly proposed production system enables the development of massive hydrate production fields on the sea bed with high production rates that are economically viable. 4 refs., 7 figs.

  19. Phytoremediation of dredged marine sediment: monitoring of chemical and biochemical processes contributing to sediment reclamation.

    Science.gov (United States)

    Masciandaro, G; Di Biase, A; Macci, C; Peruzzi, E; Iannelli, R; Doni, S

    2014-02-15

    In this study, a pilot phytoremediation experiment was performed to treat about 80 m(3) of silty saline sediments contaminated by heavy metals and organic compounds. After preliminary mixing with a sandy soil and green compost application, three different plant treatments [Paspalum vaginatum (P); P. vaginatum + Spartium junceum (P + S); P. vaginatum + Tamarix gallica (P + T)] were compared to each other and to an unplanted control (C) in order to evaluate the plant efficiency in remediating and ameliorating agronomical and functional sediment properties. The experiment was monitored for one year after planting by taking sediment samples at two depths and performing several chemical and biochemical analyses. After one year, the increase in hydrolytic enzyme and dehydrogenase activities indicated the stimulation of sediment functionality. Additionally, the availability of energy sources derived from organic matter application and plant-root activity promoted the formation of a stable organic matter fraction. Finally, P + S and P + T were also effective in decontaminating polluted marine sediments from both organic (total petroleum hydrocarbons, TPH) and inorganic (heavy metal) pollutants. PMID:24486533

  20. Oxidation of pyrite and iron sulfide by manganese dioxide in marine sediments

    DEFF Research Database (Denmark)

    Schippers, A.; Jørgensen, BB

    2001-01-01

    Oxidation of pyrite (FeS2) under anaerobic conditions in marine sediments is experimentally shown for the first time. In slurry experiments with (FeS2)-Fe-55 and a MnO2 rich marine sediment an oxidation of (FeS2)-Fe-55 was detected which decreased with depth and decreasing concentration of MnO2 i...

  1. Depositional environment, ichnological features and oxygenation of Permian to earliest Triassic marine sediments in central Spitsbergen, Svalbard

    Directory of Open Access Journals (Sweden)

    Alfred Uchman

    2016-05-01

    Full Text Available Late Early Permian–lowermost Triassic carbonate, siliceous (spiculites and clastic marine sediments in the Marmierfjellet area (Isfjorden, central Spitsbergen contain a relatively diverse and abundant trace fossil assemblage providing important information about the depositional processes. The Vøringen Member (Late Artinskian–Kungurian of the Kapp Starostin Formation (Late Artinskian–? Changhsingian contains trace fossils (Nereites, Phycosiphon, Zoophycos and Arenicolites—common in tempestites typical of the proximal–archetypal Cruziana ichnofacies, which indicates lower shoreface. Nereites, Phycosiphon and Zoophycos, accompanied by other rare trace fossils, characterize the Svenskegga and Hovtinden members of the Kapp Starostin Formation. They are interpreted as the distal Cruziana ichnofacies, possibly transitional to the Zoophycos ichnofacies typical of the lower offshore zone. However, the sporadic occurrences of Arenicolites and Macaronichnus can point to episodic shallowing to upper offshore–lower shoreface. The lowest part of the Triassic Vikinghøgda Formation (Induan–Olenekian contains a very low-diverse ichnoassemblage composed of a few simple and branched forms ascribed to the impoverished Cruziana ichnofacies (lower to upper offshore environment, which is attributed to the early recovery stage after the Permian–Triassic extinction. The trace fossils and loss of primary sedimentary structures caused by intense bioturbation throughout most of the section point to generally oxygenated pore waters on the sea floor. However, some horizons, especially laminated black shales, display reduced or no bioturbational activity. These horizons also show high V/(V+Ni ratios, which indicate oxygen-depleted sediments with periods of anoxic conditions. A remarkable black shale unit deposited under anoxic and sulphidic conditions occurs at the Permian–Triassic transition.

  2. Alternative procedure to determine radionuclide concentrations for marine sediment dating

    International Nuclear Information System (INIS)

    The development of an alternative method to prepare and to measure marine sediment samples for dating purpose using high resolution gamma spectrometry is given. To calculate the 137 Cs and the supported and unsupported 210 Pb concentrations, cylindrical tablets subjected to different pressures were analyzed. Mass attenuation coefficients (MAC) were determined by our variant of the transmission method, the Bragg law (using MACs provided by the web program XCOM) and the method of average composition of the analyzed sediment samples. The differences between obtained results are smaller than the experimental error (10%). The influence of pressure and sediment mass on the MAC, mechanical stability of the sample, and self-absorption corrections for different gamma energies is studied. Optimal dimensions of the tablets were determined from considerations on the infinite thickness, minimum detectable activity, precision of results, radiation self-absorption and geometric efficiency. Based on the differential peak absorption analysis, through a relative efficiency curve, a new method to evaluate the existence of radioactive equilibrium between 226 Ra, 222 Rn and its progeny is given. Experimental error of the proposed methodology is evaluated, as well as accuracy, precision and detection limit. With the use of developed methodology, the 210 Pb, 226 Ra and 137 Cs activities in recent sediment samples from near shore of the Orinoco River Delta were determined. The results were comparable with the obtained by two of the most used methods, while precision is improved and radiation self-absorption in sample container is avoided since sample encapsulation is not required. (Full Text)

  3. Recent Advances on Lipid Biomarkers in Marine Sediments

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-lin

    2014-01-01

    This paper reviews the recent advances of marine biomarker. Biomarkers of marine microorganisms are also included. It is important to the origin of marine biological and the monitor and evaluation of marine environment.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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. PMID:26178383

  7. Properties of bricks produced from Greenlandic marine sediments

    DEFF Research Database (Denmark)

    Bertelsen, Ida Maria Gieysztor; Belmonte, Louise Josefine; Chen, Wan;

    2015-01-01

    ). Miniature bricks werethen prepared according to the optimal conditions and formed at a pressure of 20 MPa, fired at 1020 Cfor 3:5 days at the brickwork Wienerberger Tegl in Helsinge, Denmark. The durability properties suchas porosity, water absorption, bulk density, linear shrinkage, and compressive...... submersion in cold water to fulfilthe requirements for severe weathering according to ASTM-C62 (2013). It was concluded that the firingtemperature needed to be increased in order to obtain a more durable brick-type, suitable for the Arcticclimate.......This study investigated the possibility of a local brick production from fine grained marine sediments (MS) near Sisimiut, Greenland. The assessment is based on the physical and mechanical properties of clay bricks concerning the resistance to the harsh, Arctic weather conditions, together with an...

  8. Intercomparison of radionuclide measurements in marine sediment sample IAEA-135

    International Nuclear Information System (INIS)

    The results of an intercomparison exercise on a marine sediment from Irish Sea, IAEA-135, designed for the determination of artificial and natural radionuclides levels, are reported. The data from 151 laboratories representing 51 countries have been evaluated. The following are the recommended values, with confidence intervals, for 40K, 60Co, 134Cs, 137Cs, 154Eu, 155Eu, 226Ra, 228Ra, 232Th,238Pu, 239+240Pu (Reference date: 1 January 1992). Information values for 57Co, 90Sr, 106Ru, 125Sb, 210Pb, 210Po, 228Th, 230Th, 234U, 235U, 238U and 241Am are also reported. All values are expressed in Bq kg-1 dry weight. (author)

  9. Anoxic environments and oil source bed genesis

    Energy Technology Data Exchange (ETDEWEB)

    Demaison, G.J. (Chevron Overseas Petroleum Inc., San Francisco, CA); Moore, G.T.

    1980-01-01

    The anoxic, aquatic, environment is a mass of water so depleted in oxygen that virtually all aerobic biological activity has ceased. Anoxic conditions occur where the demand for oxygen in the water column exceeds the supply. The specific cause for preferential lipid enrichment probably relates to the biochemistry of anaerobic bacterial activity. Recent evidence suggests that ancient organic-rich sediments containing hydrogen-rich kerogens (potential oil source beds) were deposited in similar anoxic environments. We propose the following classification for modern aquatic anoxic settings: (1) Large anoxic lakes - Permanent stratification promotes development of anoxic bottom water, particularly in large, deep lakes, which are not subject to seasonal overturn, e.g., Lake Tanganyika. (2) Anoxic silled basins - Landlocked silled basins with positive water balance tend to become anoxic. Typical are the Baltic and Black Seas. In arid region seas (Red and Mediterranean Seas), evaporation exceeds river inflow, causing negative water balance and well-aerated, nutrient-depleted bottom waters. (3) Anoxic layers caused by upwelling - Develop only when the oxygen supply in deep water cannot match demand by decaying organisms. Examples are the Benguela current and Peru coastal upwelling. (4) Open ocean anoxic layers - Found at intermediate depths in the northeastern Pacific and northern Indian Oceans; due to distance from deep, oxygenated polar water sources. Analogous to world-wide anoxic events at times of global climatic warm-ups and major transgressions, as in late Jurassic and middle Cretaceous time. Petroleum exploration can be greatly assisted by using geochemistry to identify paleo-anoxic events in the stratigraphic record. Recognition of the proposed anoxic models in ancient sedimentary basins should help in regional mapping of oil shales and oil-source beds. 17 figures.

  10. Marine sediments as a radioactive pollution repository in the world

    International Nuclear Information System (INIS)

    During a time period little longer than 60 years, it has been created a radioactive pollution background over the natural one, which started in 1945 and it has been growing up since then, due to several nuclear tests, minor nuclear reactors failure and four major accidents: Wind Scale, Three Mile Island, Chernobyl and Fukushima. This radioactive polluting background can be easily detected through 137Cs fission product, which by the effect of wind, river currents and rain has been accumulated in marine sediments, mainly because sea represents about 80 % of earth's surface. Since energy demand has been growing up with no interruption during last two centuries, and nuclear energy seems to be the largest available source, it is very likely a great expansion of nuclear energy during twenty-first century. So, this paper presents results obtained in strategic points of the two large littorals in Mexico: Gulf and Pacific Ocean, as an attempt to establish there some figure to evaluate the present radioactive pollution. An adequate figure to do it, seems to be the quotient of activity per gram of 137Cs in marine sediments (Bq137Cs/g), divided by activity per gram of 40K natural radioactivity (Bq40K/g). When this result is multiplied by 100 the percentage of polluting radioactivity (137Cs) related to natural radioactivity (40K) is obtained. This percentage seems to be useful to evaluate the importance of radioactive pollution from 4 points of view: a) calculate the extent of already radioactive pollution present in the seas of world; b) avoid the panic in case of nuclear accidents, c) what will be the growing up rate in the future; d) if it is possible to keep one decreasing rate at same decaying rate of 137Cs (t1/2 = 30.07 years), since from 1945, starting time of radioactive pollution, it has decayed only about 2.2 half lives. (author)

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

    Science.gov (United States)

    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

  12. Fine scale remobilisation of Fe, Mn, Co, Ni, Cu and Cd in contaminated marine sediment

    DEFF Research Database (Denmark)

    Tankere-Muller, Sophie; Zhang, Hao; Davison, William;

    2007-01-01

    Contaminated sediment from a marine harbour was maintained for 16 months in two flumes that continuously re-circulated the overlying water, sustaining a smooth flow at the sediment surface. The sediment was placed in one flume intact, while for the other it was pre-homogenised. The concentrations...

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

    Science.gov (United States)

    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

  14. Integrated approach to the toxicity evaluation of Irish marine sediments: exotoxicological assessment

    OpenAIRE

    Macken, Ailbhe

    2007-01-01

    The quality of sediment in any aquatic ecosystem is vital to the health of that system. Sediments have been recognised as a major repository for persistent toxic substances. If sediments become sufficiently polluted they can lead to the disruption of surrounding natural biological communities. Therefore the monitoring of sediment quality is essential for successful ecosystem functioning in the marine environment. The aim of the present study was to employ an integrated approach of the toxicit...

  15. Effect of sediment properties on the sorption of C{sub 12}-2-LAS in marine and estuarine sediments

    Energy Technology Data Exchange (ETDEWEB)

    Rico-Rico, Angeles [Institute for Risk Assessment Sciences, Utrecht University, Yalelaan 2, 3508 TD Utrecht (Netherlands)], E-mail: a.ricorico@uu.nl; Temara, Ali [Procter and Gamble Company, Central Product Safety, Temselaan 100, 1853 Strombeek-Bever (Belgium); Behrends, Thilo [Department of Earth Sciences-Geochemistry, Faculty of Geosciences, Utrecht University, 3508 TA Utrecht (Netherlands); Hermens, Joop L.M. [Institute for Risk Assessment Sciences, Utrecht University, Yalelaan 2, 3508 TD Utrecht (Netherlands)

    2009-02-15

    Linear alkylbenzene sulfonates (LAS) are anionic high production volume surfactants used in the manufacture of cleaning products. Here, we have studied the effect of the characteristics of marine and estuarine sediments on the sorption of LAS. Sorption experiments were performed with single sediment materials (pure clays and sea sand), with sediments treated to reduce their organic carbon content, and with field marine and estuarine sediments. C{sub 12}-2-LAS was used as a model compound. Sorption to the clays montmorillonite and kaolinite resulted in non-linear isotherms very similar for both clays. When reducing the organic content, sorption coefficients decreased proportionally to the fraction removed in fine grain sediments but this was not the case for the sandy sediment. The correlation of the sediment characteristics with the sorption coefficients at different surfactant concentrations showed that at concentrations below 10 {mu}g C{sub 12}-2-LAS/L, the clay content correlated better with sorption, while the organic fraction became more significant at higher concentrations. - Sorption of C{sub 12}-2-LAS to marine sediments mainly depends on both clay and organic carbon content. The importance of each parameter varies with the surfactant concentration.

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

    Science.gov (United States)

    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

  17. ACCUMULATION OF POLYCHLORINATED ORGANIC CONTAMINANTS FROM SEDIMENT BY THREE BENTHIC MARINE SPECIES

    Science.gov (United States)

    A laboratory experiment was conducted to measure the accumulation of selected polychlorinated compounds by marine benthos exposed to environmentally contaminated sediment. andworms (Nereis virens), clams (Macoma nasuta), and grass shrimp (Palaemonetes pugio) were exposed to sedim...

  18. Degradation of dead microbial biomass in a marine sediment

    International Nuclear Information System (INIS)

    The availability of dead microbial biomass in a marine beach sand to degradation and mineralization was examined. Microbial sand populations were labeled with [14C]glutamic acid, [3H]adenine, or [3H]thymidine and killed with chloroform. Live sand or seawater (or both) was added to the sterile labeled sand, and biochemical components of the populations were monitored for 10 days. Labeled RNA was degraded more quickly than labeled DNA, but both nucleic acids were degraded to approximately the same extent (60 to 70%). 3H2O was a major acid-soluble breakdown product. RNA (and possibly DNA) breakdown products were reincorporated into DNA (and possibly RNA) during the incubation period. In addition to metabolite salvage, 32% of the total macromolecular 14C was respired in the 10-day period regardless of whether sand or seawater was used as the inoculum. Respiration was essentially complete in 3 days, whereas nucleic acid degradation continued throughout the 10-day incubation. The results indicate that dead microbial biomass is a labile component of the sediment ecosystem

  19. Microbes of deep marine sediments as viewed by metagenomics

    Science.gov (United States)

    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.

  20. Elemental depth profiles in marine sediments of Singapore coastal waters

    International Nuclear Information System (INIS)

    Thirty-eight core sediment samples were recently collected from different locations of the Singapore coastal region. The aim of the project was to trace the history of marine pollution in various coastal regions and to determine the impact of industrial activities. Two nuclear analytical techniques were employed in this study: particle induced X-ray emission (PIXE), Rutherford backscattering (RBS) as well as X-ray fluorescence (XRF). Combined together these techniques provide an excellent tool to determine elemental concentrations of more than 30 elements with detection limits as low as few ppm. Our results show that elemental concentrations in most of the regions do not show a significant variation with depth. However, in regions where industrial and shipping activities are high, for example the Port of Singapore area and the northern part of Johore Straits, the concentrations of metals like Cr, Ni, Cu, Zn, Sn and Pb were found to have an obvious decreasing trend with the depth. In these cores, concentrations in the top 10-15 cm were sometimes ten times higher than the corresponding base line concentrations. Elemental depth profiles of Ni, Cu, Zn, As, Sn and Pb and their mean concentrations in various regions are reported and discussed

  1. Radiation technology for treatment of PCB-s in marine sediment

    International Nuclear Information System (INIS)

    Full text: The primary objective of this study is to achieve total dechlorination of marine sediment containing PCBs and to convert those PCBs to the biphenyl molecules into benign low molecular weight compounds by using ionizing radiation. In the current investigation it is examined the radiation-induced degradation of PCBs in various aqueous surfactant combination solutions. The radiolytic decay of PCBs in marine sediment in presence of surfactants is evident in the initial samples examined

  2. Presence of uranium and plutonium in marine sediments from gulf of Tehuantepec, Mexico

    International Nuclear Information System (INIS)

    Uranium and plutonium were determined in the Tehua II-21 sediment core collected from the Gulf of Tehuantepec, Mexico. The analyses were performed using radiochemical separation and alpha spectroscopy. Activity concentrations of alpha emitters in the sediment samples were from 2.56 to 43.1 Bq/kg for 238U, from 3.15 to 43.1 Bq/kg for 234U and from 0.69 to 2.95 Bq/Kg for 239+240Pu. Uranium activity concentration in marine sediment studied is generally high compared with those found in sediments from other marine coastal areas in the world. The presence of relatively high concentrations of anthropogenic plutonium in the sediments from the Gulf of Tehuantepec suggests that anthropogenic radionuclides have been incorporated and dispersed into the global marine environment. (author)

  3. Experimental investigation on consistency limits of cement and lime-stabilized marine sediments.

    Science.gov (United States)

    Wang, DongXing; Zentar, Rachid; Abriak, Nor Edine; Xu, WeiYa

    2012-06-01

    This paper presents the effects of treatments with cement and lime on the consistency limits of marine sediments dredged from Dunkirk port. The Casagrande percussion test and the fall cone test were used to determine the liquid limits of raw sediments and treated marine sediments. For the evaluation of the plastic limits, the results of the fall cone test were compared with those obtained by the rolling test method. The relationship between the water contents and the penetration depths for the determination of the liquid limit and the plastic limit was explored. Liquid limits at 15.5 mm and plastic limits at 1.55 mm seem to be a more appropriate choice for the studied marine sediments compared with the limits determined by other used prediction methods. Finally, the effect of cement treatment and lime treatment on the Casagrande classification of the studied sediments was investigated according to the different prediction results. PMID:22856290

  4. Spatial and seasonal variation in microbial diversity in marine subtidal sediments in relation to sediment geochemistry and heavy metal pollution

    OpenAIRE

    Pede, A.; Gillan, D.; Gao, Y.; Billon, G.; Lesven, L.; Leermakers, M; Baeyens, W.; Vyverman, W.; Sabbe, K

    2009-01-01

    Very little information is available on the diversity and structure of microbial communities in marine subtidal sediments, especially for micro-eukaryotes. In the framework of the Belgian MICROMET project, we investigated spatial and seasonal (February vs July) variation patterns in the molecular diversity of archaeal, bacterial and eukaryotic communities in 9 subtidal stations in the Belgian Continental Plate (BCP) in relation to sediment granulometry, geochemistry and metal contamination. M...

  5. Burrowing and avoidance behaviour in marine organisms exposed to pesticide-contaminated sediment

    DEFF Research Database (Denmark)

    Møhlenberg, Flemming; Kiørboe, Thomas

    1983-01-01

    Behavioural effects of marine sediment contaminated with pesticides (6000 ppm parathion, 200 ppm methyl parathion, 200 ppm malathion) were studied in a number of marine organisms in laboratory tests and in situ. The burrowing behaviour in Macoma baltica, Cerastoderma edule, Abra alba, Nereis dive...

  6. Origin and geochemical behavior of uranium in marine sediments. Utilization of the 234U/238U ratio in marine geochemistry

    International Nuclear Information System (INIS)

    The first part of this thesis presents the current situation of knowledge of uranium in marine environment. The second part describes the methods of analysis as well as the material support of the study, i.e., the sediments and marine deposits investigated. The third part is dedicated to the study of uranium mobility in marine sediments characterized by detrital terrigenous composition (pelagic clays). This approach allowed quantifying the entering and leaving flux of uranium after the sediment settling and, to discuss, on this basis, the consequences on the uranium oceanic balance. In the third part the origin and behavior of uranium in zones of high surface productivity is studied. The uranium enrichments observed in the hemi-pelagic sediments of the EUMELI (J.G.O.F.S.-France) programme will constitute a material of study adequate for measuring the variations in the 234U/238U ratio in solid phase, in response to the oxido-reducing characteristics of the sediment. Thus establishing the origin of the trapped uranium has been possible. Also, the nature of the sedimentary phases related to uranium in bio-genetic sediments in the Austral Ocean was determined. Thus a relationship between the variations in the 234U/238 and the diagenetic transformations was possible to establish. Finally in the fifth part a study of the behavior of uranium in a polymetallic shell characteristic for deposits of hydrogenized origin

  7. Species Richness and Adaptation of Marine Fungi from Deep-Subseafloor Sediments

    OpenAIRE

    Rédou, Vanessa; Navarri, Marion; Meslet-Cladière, Laurence; Barbier, Georges; Burgaud, Gaëtan

    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. I...

  8. Pathways and Microbiology of Thiosulfate Transformations and Sulfate Reduction in a Marine Sediment (Kattegat, Denmark)

    DEFF Research Database (Denmark)

    JØRGENSEN, BB; BAK, F.

    1991-01-01

    Reductive and oxidative pathways of the sulfur cycle were studied in a marine sediment by parallel radiotracer experiments with (SO4(2-))-S-35, (H2S)-S-35, and (S2O3(2-))-S-35 injected into undisturbed sediment cores. The distributions of viable populations of sulfate- and thiosulfate-reducing ba...

  9. Chemoautotrophic Carbon Fixation Rates and Active Bacterial Communities in Intertidal Marine Sediments

    NARCIS (Netherlands)

    Boschker, H.T.S.; Vasquez-Cardenas, D.; Bolhuis, H.; Moerdijk-Poortvliet, T.C.W.; Moodley, L.

    2014-01-01

    Chemoautotrophy has been little studied in typical coastal marine sediments, but may be an important component ofcarbon recycling as intense anaerobic mineralization processes in these sediments lead to accumulation of high amounts ofreduced compounds, such as sulfides and ammonium. We studied chemo

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  11. Comparative study of plutonium and americium bioaccumulation from two marine sediments contaminated in the natural environment

    International Nuclear Information System (INIS)

    Plutonium and americium sediment-animal transfer was studied under controlled laboratory conditions by exposure of the benthic polychaete Nereis diversicolor (O. F. Mueller) to marine sediments contaminated by a nuclear bomb accident (near Thule, Greenland) and nuclear weapons testing (Enewetak Atoll). In both sediment regimes, the bioavailability of plutonium and 241Am was low, with specific activity in the tissues 241Am occurred and 241Am uptake from the Thule sediment was enhanced compared to that from lagoon sediments of Enewetak Atoll. Autoradiography studies indicated the presence of hot particles of plutonium in the sediments. The results highlight the importance of purging animals of their gut contents in order to obtain accurate estimates of transuranic transfer from ingested sediments into tissue. It is further suggested that enhanced transuranic uptake by some benthic species could arise from ingestion of highly activity particles and organic-rich detritus present in the sediments. (author)

  12. Radiolytic dechlorination of polychlorinated biphenyls in transformer oil and in marine sediment

    International Nuclear Information System (INIS)

    Radiolytic dechlorination of polychlorinated biphenyls (PCBs) in transformer oil and in marine sediments has been studied. At low PCB concentrations, complete degradation of the PCBs in transformer oil was achieved without degradation of the oil. Addition of an organic base, triethylamine, enhances the radiolytic dechlorination yield. The mechanism of dechlorination has been shown to involve electron transfer to PCBs from various aromatic radical anions formed in the irradiated oil. At high PCB concentrations, large amounts of triethylamine were necessary to achieve complete radiolytic dechlorination. Preliminary results on PCB-contaminated marine sediments demonstrate that addition of 2-propanol to the sediment/water slurry increases the effectiveness of the electron beam treatment

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

    Energy Technology Data Exchange (ETDEWEB)

    White, P.J.; Kohn, N.P.; Gardiner, W.W.; Word, J.Q. [Battelle/Marine Sciences Lab., Sequim, WA (United States)

    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.

  14. Anaerobic denitrification in fungi from the coastal marine sediments off Goa, India.

    Science.gov (United States)

    Cathrine, Sumathi J; Raghukumar, Chandralata

    2009-01-01

    Denitrification is a microbial process during which nitrate or nitrite is reduced under anaerobic condition to gaseous nitrogen. The Arabian Sea contains one of the major pelagic denitrification zones and in addition to this, denitrification also takes places along the continental shelf. Prokaryotic microorganisms were considered to be the only players in this process. However recent studies have shown that higher microeukaryotes such as fungi can also adapt to anaerobic mode of respiration and reduce nitrate to harmful green house gases such as NO and N2O. In this study we examined the distribution and biomass of fungi in the sediments of the seasonal anoxic region off Goa from two stations. The sampling was carried out in five different periods from October 2005, when dissolved oxygen levels were near zero in bottom waters to March 2006. We isolated mycelial fungi, thraustochytrids and yeasts. Species of Aspergillus and thraustochytrids were dominant. Fungi were isolated under aerobic, as well as anaerobic conditions from different seasons. Four isolates were examined for their denitrification activity. Two cultures obtained from the anoxic sediments showed better growth under anaerobic condition than the other two cultures that were isolated from oxic sediments. Our preliminary results suggest that several species of fungi can grow under oxygen deficient conditions and participate in denitrification processes. PMID:18834939

  15. Geochemistry of marine sediments of the Brazilian Northeastern continental shelf

    Directory of Open Access Journals (Sweden)

    Fernanda Souza do Nascimento

    2010-01-01

    Full Text Available The marine sediment samples collected from the northeastern Brazilian continental shelf, at water depths between 20 and 80 m, consisted mainly of sands with an almost total absence of gravel and granules. Medium, coarse and very coarse sand grains are mostly composed of halimeda, lithothamnium, rodoliths and bioclastic sands with a carbonate content varying between 77 and 96 %. The chemistry in general shows a decreasing content of Ca (86.1 % >Si (6 % > Cl (3.6 % > Sr (0.8 % > K (0.66 % > S (0.62 % > Al (0.6 % > Na (0.55% > Mg (0.43 % > Fe (0.4 % > P (0.2 % > Br (0.04 % in the samples. There was no correlation between CaCO3 and chemical contents and grain size with depth and bio-components. With the exception of Sr of marine origin, all other elements (P, S, Br, Cl, Fe are of continental origin. The lithothamnium of some offshore samples shows higher CaCO3 content, while Mg and Na are present only in halimedas. Bioclastic sands contain no Br, and silt and clay fractions are rare and characterize samples closer to the coast. These marine bioclastic granulates are of very pure biogenic calcium carbonates and are thus highly to be recommended for economic purposes.Os granulados marinhos, da Plataforma Continental do nordeste brasileiro, coletados de profundidades entre 20 e 80 m, são predominantemente areias cascalhosas constituídas de halimedas, litotames, rodolitos e areias bioclásticas, cujos teores de carbonatos variam de 77 a 96 %. A concentração média geral de elementos químicos na ordem decrescente é Ca (86.1 % > Si (6 % > Cl (3.6 % > Sr (0.8 % > K (0.66 % > S (0.62 % > Al (0.6 % > Na (0.55 % > Mg (0.43 % > Fe (0.4 % > P (0.2 % > Br (0,04 %, independentemente da profundidade e tipo de bio-componente. Com exceção do Sr, que é de origem marinha, os demais elementos (P, S, Br, Cl, Fe são de origem continental. Elementos como Mg e Na foram restritos às halimedas em apenas duas amostras, enquanto Br não foi detectado nas areias

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  18. The microbial nitrogen cycling potential in marine sediments is impacted by polyaromatic hydrocarbon pollution

    Directory of Open Access Journals (Sweden)

    Nicole M Scott

    2014-03-01

    Full Text Available During petroleum 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, if the sediments are aerobic, within the surface layer of marine sediments resulting in 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 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.

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

    Science.gov (United States)

    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...

  20. Sediment distribution coefficients and concentration factors for biota in the marine environment

    International Nuclear Information System (INIS)

    In 1985 the IAEA published Technical Reports Series No. 247 (TRS 247), Sediment Kds and Concentration Factors for Radionuclides in the Marine Environment, which provided sediment distribution coefficients (Kds) and concentration factor (CF) data for marine biological material that could be used in models simulating the dispersion of radioactive waste that had been disposed of in the sea. TRS 247 described an approach for calculating sediment or water Kds using stable element geochemical data developed by J.M. Bewers, even though the use of field derived data was emphasized whenever possible. Over the years, TRS 247 has proved to be a valuable reference for radioecologists, marine modellers and other scientists involved in assessing the impact of radionuclides in the marine environment. In 2000 the IAEA initiated a revision of TRS 247 to take account of the new sets of data obtained since 1985.The outcome of this work is this report, which contains revised sediment Kds for the open ocean and ocean margins and CFs for marine biota. CFs for deep ocean ferromanganese nodules. In addition, this report contains CFs for a limited number of elements for marine mammals not included in TRS 247. This revision was carried out at three IAEA Consultants Meetings held in Monaco and Vienna between April 2000 and December 2002

  1. Extent and toxicity of contaminated marine sediments in Southeastern Florida

    OpenAIRE

    Cantillo, A. Y.; Lauenstein, G. G.

    2004-01-01

    Thirty sites were sampled in southern Biscayne Bay and Manatee Bay in December 1999 to determine the extent of toxicity in sediments. Analyses and assays included: pesticides and phenols in seawater; chemical contaminants in sediment; amphipod mortality, HRGS P450, sea urchin sperm fertilization and embryology, MicrotoxTM, MutatoxTM, grass shrimp AChE and juvenile clam mortality assays; sea urchin sperm, amphipod and oyster DNA damage; and benthic community assessment. Sediment sites near the...

  2. Feasibility study of chemical stabilization of dredged marine sediment

    OpenAIRE

    FURLAN, Ana Paola; RAZAKAMANANTSOA, Andry; Liang, Yingjie; Deneele, Dimitri

    2015-01-01

    Chemical stabilization is one of techniques which can improve mechanical and hydraulic properties of dredged sediments. This paper presents an experimental study focused on different techniques of stabilization of dredged sediment from La Baule-Le Pouliguen (France). Dredged sediments are stabilized with lime, Portland cement and fly ash. Three mixes were produced and submitted to uniaxial compression strength (UCS), indirect tensile strength (ITS) and shear tests at different curing ages. In...

  3. Potential Impacts of PCBs on Sediment Microbiomes in a Tropical Marine Environment

    Directory of Open Access Journals (Sweden)

    James S. Klaus

    2016-02-01

    Full Text Available Within the tropical marine study site of Guánica Bay, Puerto Rico, polychlorinated biphenyls (PCBs are subjected to coastal and oceanic currents coupled with marine microbial and geochemical processes. To evaluate these processes a hydrodynamic model was developed to simulate the transport of PCBs within nearshore and offshore marine areas of Guánica Bay. Material transport and circulation information from the model were matched with measurements from samples collected from within the bay. These samples, consisting of both intertidal and submerged sediments, were analyzed for physical characteristics (organic carbon, grain size, and mineralogy, microbial characteristics (target bacteria levels and microbial community analyses, presence of PCBs, and PCB-degrading enzymes. Results show that the bay geometry and bathymetry limit the mixing of the extremely high levels of PCBs observed in the eastern portion of the bay. Bay bottom sediments showed the highest levels of PCBs and these sediments were characterized by high organic carbon content and finer grain size. Detectable levels of PCBs were also observed within sediments found along the shore. Microbes from the bay bottom sediments showed a greater relative abundance of microbes from the Chloroflexi, phylum with close phylogenetic associations with known anaerobic PCB-degrading organisms. Based on quantitative PCR measurement of the biphenyl dioxygenase gene, the intertidal sediments showed the greatest potential for aerobic PCB degradation. These results elucidate particular mechanisms of PCB’s fate and transport in coastal, tropical marine environments.

  4. Occurrence and sorption properties of arsenicals in marine sediments

    DEFF Research Database (Denmark)

    Fauser, Patrik; Sanderson, Hans; Hedegaard, Rikke Susanne Vingborg;

    2013-01-01

    The content of total arsenic, the inorganic forms: arsenite (As(III)) and arsenate (As(V)), the methylated forms: monomethylarsonic acid and dimethylarsinic acid (DMA), trimethylarsenic oxide, tetramethylarsenonium ion and arsenobetaine was measured in 95 sediment samples and 11 pore water samples...... from the Baltic Sea near the island of Bornholm at depths of up to 100 m. As(III+V) and DMA were detected in the sediment and As(III+V) was detected in the sediment pore water. Average total As concentration of 10.6 ± 7.4 mg/kg dry matter (DM) in the sediment corresponds to previously reported values...

  5. Distribution of radionuclides among green alga, marine sediments and sea water

    International Nuclear Information System (INIS)

    Distributions of radionuclides among green alga (Ulva pertusa), marine sediment and sea water were examined in laboratory experiments with radioisotope tracers to look into the behavior of the radionuclides released into the coastal sea. Marine sands from the five different seashores along the coast of Japan were used. Distributions of 60Co, 95Zr-95Nb and 106Ru-106Rh in these sands were by far the highest of the three components (marine sand, sea water and marine alga). The distributions of the three radionuclides had not so large fluctuations among the five marine sands and were considered to be rather constant. The total amount found in marine sand and green alga was about 90% for the three radionuclides but about 20% for 137Cs on the average in two weeks after the start of the experiments. The activity ratio of marine sediment (radioactivity in 1 g of sediment/radioactivity in 1 ml of sea water) was 4000 for 60co, 30 for 137Cs, 1800 for 95Zr-95Nb and 900 for 106Ru-106Rh. (auth.)

  6. An open ocean record of the Toarcian oceanic anoxic event

    Directory of Open Access Journals (Sweden)

    D. R. Gröcke

    2011-11-01

    Full Text Available Oceanic anoxic events were time intervals in the Mesozoic characterized by widespread distribution of marine organic matter-rich sediments (black shales and significant perturbations in the global carbon cycle. These perturbations are globally recorded in sediments as carbon isotope excursions irrespective of lithology and depositional environment. During the early Toarcian, black shales were deposited on the epi- and pericontinental shelves of Pangaea, and these sedimentary rocks are associated with a pronounced (ca. 7 ‰ negative (organic carbon isotope excursion (CIE which is thought to be the result of a major perturbation in the global carbon cycle. For this reason, the lower Toarcian is thought to represent an oceanic anoxic event (the T-OAE. If the T-OAE was indeed a global event, an isotopic expression of this event should be found beyond the epi- and pericontinental Pangaean localities. To address this issue, the carbon isotope composition of organic matter (δ13Corg of lower Toarcian organic matter-rich cherts from Japan, deposited in the open Panthalassa Ocean, was analysed. The results show the presence of a major (>6 ‰ negative excursion in δ13Corg that, based on radiolarian biostratigraphy, is a correlative of the lower Toarcian negative CIE known from Pangaean epi- and pericontinental strata. A smaller negative excursion in δ13Corg (ca. 2 ‰ is recognized lower in the studied succession. This excursion may, within the current biostratigraphic resolution, represent the excursion recorded in European epicontinental successions close to the Pliensbachian/Toarcian boundary. These results from the open ocean realm suggest, in conjunction with other previously published datasets, that these Early Jurassic carbon cycle perturbations affected the active global reservoirs of the exchangeable carbon cycle (deep marine, shallow marine, atmospheric.

  7. Environmental process descriptors for TNT, TNT-related compounds and picric acid in marine sediment slurries

    International Nuclear Information System (INIS)

    Process descriptors were determined for picric acid, TNT, and the TNT-related compounds 2,4DNT, 2,6DNT, 2ADNT, 4ADNT, 2,4DANT, 2,6DANT, TNB and DNB in marine sediment slurries. Three marine sediments of various physical characteristics (particle size ranging from 15 to >90% fines and total organic carbon ranging from <0.10 to 3.60%) were kept in suspension with 20 ppt saline water. Concentrations of TNT and its related compounds decreased immediately upon contact with the marine sediment slurries, with aqueous concentrations slowly declining throughout the remaining test period. Sediment-water partition coefficients could not be determined for these compounds since solution phase concentrations were unstable. Kinetic rates and half-lives were influenced by the sediment properties, with the finer grained, higher organic carbon sediment being the most reactive. Aqueous concentrations of picric acid were very stable, demonstrating little partitioning to the sediments. Degradation to picramic acid was minimal, exhibiting concentrations at or just above the detection limit

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

    Energy Technology Data Exchange (ETDEWEB)

    Hafidz, B. Y.; Asnor, A. S.; Terence, R. C.; Mohamed, C. A. R. [School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia 43600, Bangi, Selangor (Malaysia)

    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 situation of marine sediments in the pathway of radionuclides to man

    International Nuclear Information System (INIS)

    It is widely accepted that the marine sediments are the major reservoir of the radionuclides which are discharged into the coastal sea water. The radionuclides sorpted on the sediments would be recycled in the sea water and be accumulated by marine organisms. And some of the sorpted radionuclides would be transfered to the worm (a kind of benthos) habited in the sediments through their surface or digestive tract and then to the fishes which prey upon the benthos. Therefore, it is important to learn whether the sediments as a ''sink'' may not later become a ''source'' of these contaminants. In this paper, the problem is discussed refering to few reports which are published up to this time. Renfro estimated that about one per cent of 65Zn in the sediment would be transfered to Nereis diversicolor which directly contacts with the sediments: On the recycling of 65Zn from the sediments to the sea water, Seymour and Nelson determined the 65Zn level of 8/100 in the sea water after twelve months following shutdown of reactor. Thus they calculated the ecological half-lives which were affected by the radionuclides retention of the sediments. In our laboratory experiment on the interaction of sediments and Nereis diversicolor using 95Zr, 106Ru, 137Cs and 60Co, the similar results were observed except 137Cs which showed rather high rate of remobilization from the sediments to the sea water. Thus, it could be generally considered that the transfer of radionuclides via sediment would be minor to man. However, it should be born in mind that the increased amount of radionuclides by continuous discharge into sea may raise the level of radionuclides in the sediments and then benthos even with one per cent transfer rate from sediment to benthos. (auth.)

  10. Cable Bacteria in Freshwater Sediments

    DEFF Research Database (Denmark)

    Risgaard-Petersen, Nils; Kristiansen, Michael; Frederiksen, Rasmus;

    2015-01-01

    In marine sediments cathodic oxygen reduction at the sediment surface can be coupled to anodic sulfide oxidation in deeper anoxic layers through electrical currents mediated by filamentous, multicellular bacteria of the Desulfobulbaceae family, the so-called cable bacteria. Until now, cable...... bacteria have only been reported from marine environments. In this study, we demonstrate that cable bacteria also occur in freshwater sediments. In a first step, homogenized sediment collected from the freshwater stream Giber Å, Denmark, was incubated in the laboratory. After 2 weeks, pH signatures and...... marine cable bacteria, with the genus Desulfobulbus as the closest cultured lineage. The results of the present study indicate that electric currents mediated by cable bacteria could be important for the biogeochemistry in many more environments than anticipated thus far and suggest a common evolutionary...

  11. Study of the sediment contamination levels in a mangrove swamp polluted by a marine oil spill

    Energy Technology Data Exchange (ETDEWEB)

    Wong, T.W.Y.; Ke, L.; Wong, Y.S.; Tam, N.F.Y. [City University of Hong Kong, Hong Kong SAR (China)

    2002-07-01

    The pattern of oil retention in mangrove sediments was studied in an effort to determine the temporal changes of petroleum hydrocarbon concentrations and composition several months after oil spills occur. Mangroves are inter-tidal wetlands in tropical and subtropical coastlines. Due to the anoxic and water logging characteristics of mangrove sediments, oil residues linger much longer in these wetlands compared to other coastal habitats. In November 2000, an accidental oil spill occurred in the Pearl River Estuary in which approximately 230,000 litres of crude oil was leaked from an oil tanker. The spilled oil migrated to the YiO, a typical mangrove swamp in Hong Kong Special Administrative Region. The degree of oil contamination in the sediments depended on the sediment texture and topography of the mangrove. The total petroleum hydrocarbon (TPH) concentration of the sediments in the most affected area near a freshwater creek flowing into the sea was 130 times higher than normal, one month after the accident. The mean TPH concentration was 2862 ug/g of dry sediment while the mean carbon preference index was 1.22 compared to the background value of 3.97. The temporal changes of the petroleum hydrocarbon level in 5 defined areas were examined for 7 months after the spill. The most polluted area next to the creek was determined to have very high TPH levels in the muddy sediments even 7 months after the spill. Oil residues infiltrated as deep as 20 cm into the sediments, making it more difficult to degrade than surface pollution and posing long-term adverse effects on trees in the area. It was determined that with growing industrialization and increasing demands for fuel and energy supply, mangroves in South China should be ranked as top priority for protection from oil spills. 19 refs., 6 tabs., 6 figs.

  12. Study of the sediment contamination levels in a mangrove swamp polluted by a marine oil spill

    International Nuclear Information System (INIS)

    The pattern of oil retention in mangrove sediments was studied in an effort to determine the temporal changes of petroleum hydrocarbon concentrations and composition several months after oil spills occur. Mangroves are inter-tidal wetlands in tropical and subtropical coastlines. Due to the anoxic and water logging characteristics of mangrove sediments, oil residues linger much longer in these wetlands compared to other coastal habitats. In November 2000, an accidental oil spill occurred in the Pearl River Estuary in which approximately 230,000 litres of crude oil was leaked from an oil tanker. The spilled oil migrated to the YiO, a typical mangrove swamp in Hong Kong Special Administrative Region. The degree of oil contamination in the sediments depended on the sediment texture and topography of the mangrove. The total petroleum hydrocarbon (TPH) concentration of the sediments in the most affected area near a freshwater creek flowing into the sea was 130 times higher than normal, one month after the accident. The mean TPH concentration was 2862 ug/g of dry sediment while the mean carbon preference index was 1.22 compared to the background value of 3.97. The temporal changes of the petroleum hydrocarbon level in 5 defined areas were examined for 7 months after the spill. The most polluted area next to the creek was determined to have very high TPH levels in the muddy sediments even 7 months after the spill. Oil residues infiltrated as deep as 20 cm into the sediments, making it more difficult to degrade than surface pollution and posing long-term adverse effects on trees in the area. It was determined that with growing industrialization and increasing demands for fuel and energy supply, mangroves in South China should be ranked as top priority for protection from oil spills. 19 refs., 6 tabs., 6 figs

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hooten, R. [Texas A and M Univ., Corpus Christi, TX (United States); Carr, R.S. [National Biological Service, Corpus Christi, TX (United States)

    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. Burrowing and avoidance behaviour in marine organisms exposed to pesticide-contaminated sediment

    Energy Technology Data Exchange (ETDEWEB)

    Mohlenberg, F.; Kiorboe, T.

    1983-02-01

    Behavioural effects of marine sediment contaminated with pesticides (6000 ppm parathion, 200 ppm methyl parathion, 200 ppm malathion) were studied in a number of marine organisms in laboratory tests and in situ. The burrowing behaviour in Macoma baltica, Cerastoderma edule, Abra alba, Nereis diversicolor and Scoloplos armiger was impaired in the contaminated sediment compared to control. The impairment was most pronounced in the laboratory tests, where almost no burrowing occured. In a very simple laboratory set-up, highly significant avoidance of the contaminated sediment was demonstrated for Crangon crangon and Solea solea, but not for Carcinus maenas and Pomatoschistus minutus. The validity of both behavioural tests was supported by in situ observations and investigations on the distribution of the species. It is concluded that both tests are useful tools in the assessment of the impact of contaminated sediments.

  16. Amphipods from marine cave sediments of the southern Iberian Peninsula: diversity and ecological distribution

    OpenAIRE

    Navarro-Barranco, Carlos; Guerra-Garc??a, Jos?? Manuel; S??nchez-Tocino, Luis; Garc??a-G??mez, Jos?? Carlos

    2014-01-01

    The present study explores the amphipod assemblages of six marine caves on the Mediterranean coast of southern Spain. Replicate samples were taken both inside and outside each marine cave in order to characterize the amphipod fauna and the physicochemical properties of the sediment. As a result, 44 amphipods species were identified. The high number of species found in a relatively limited area highlighted the richness of the Alboran Sea fauna, which is mainly due to the mixture of species fro...

  17. Rare earth elements distribution in marine sediments of Malaysia coasts

    Institute of Scientific and Technical Information of China (English)

    Rezaee; Ebrahim; Saraee; Khadijeh; Saion; B.Elias; Abdul; Khalik; Wood; Abdi; Mohammad; Reza

    2009-01-01

    In the east coast Peninsular Malaysia region,sediments are transported by several rivers from the east Malaysia into the South China Sea estuary.In the vicinity of the five river estuaries core sediments were collected in order to investigate rare earth elements(REEs) profile.Core sediments were divided into strata of between 2 to 4 cm intervals and prepared for analyzing by ICP-AES.REE concentrations of 54.3 μg/gr at 24-26 cm in EC4 increased to 114.1 μg/gr at 20-22 cm in EC5.The measured concentration of ...

  18. The Effect of Sediment Disturbance on the Carbon and Nitrogen Cycles Within Coastal Marine Lakes

    Science.gov (United States)

    Mills, A. R.; Wilson, S. R.; Jolley, D. F.

    2006-12-01

    A system allowing the ex situ quantification of the nitrogen cycle and various carbonaceous species (Organic Carbon, carbon dioxide, methane) in the air, water and sediment has been developed and used to monitor the effects of sediment disturbance on the nitrogen and carbon cycles. Measurements are made using standard wet chemical techniques for the sediment and water phases, and FTIR spectroscopy for the real-time monitoring of gas concentrations. Sediment collected from two temperate marine lakes on the eastern coast of Australia has been examined. In the laboratory it was found that the methane flux peaked three days after the initial disturbance; nitrous oxide flux peaked after 12 days while carbon dioxide flux varied throughout the experiment. Nitrite and nitrate concentrations in the overlying water peaked at the end of the second and third weeks, respectively. The total quantity of nitrogen within the system increased by ~ 35%. Sediment disturbance led to an initial release of nitrogenous nutrients from the sediment to the overlying water that were rapidly readsorbed to sediment particles and sequestered back into the sediment phase. The same technology was also adapted to allow this research to be undertaken in the field and used to study three new temperate marine sites within Lake Illawarra, New South Wales, Australia.

  19. Vertical distribution of 137Cs activity concentration in marine sediments at Amvrakikos Gulf, western of Greece

    International Nuclear Information System (INIS)

    The aim of the present work is the study of 137Cs migration in sediment column taking into account the sedimentation rate in the Amvrakikos Gulf, at the western part of Greece. Marine core sediments were collected and the measurements were performed using the high resolution gamma-ray spectrometry method. The vertical distribution of 137Cs activity concentration, as part of anthropogenic marine radioactivity, provided averaged sedimentation rate by identifying the depths of activity concentrations due to the Chernobyl accident and the nuclear tests signals. Furthermore, 137Cs measurements were reproduced using the proposed one-dimensional diffusion–advection model which provides mainly as an output, the sedimentation rate and the average diffusivity of 137Cs in the sediment column. The proposed model estimates the temporal variation of 137Cs activity concentration from 1987 (one year after the Chernobyl accident) till today (2014). - Highlights: • Two sediment cores were studied using 137Cs as a tracer. • Two peaks are observed due to nuclear tests and Chernobyl accident. • Diffusivities, as well as 137Cs apparent sedimentation speeds are estimated

  20. Sediment-worm interaction: transfer of 65Zn from marine silt by the polychaete, Nereis diversicolor

    International Nuclear Information System (INIS)

    Marine polychaete worms (Nereis diversicolor) accumulated 65Zn sorbed to silty marine sediment for 5 days and were then transferred to nonradioactive sediment in the laboratory and in the sea. The mean biological half-life (T/sub B//2/) for the laboratory worms did not differ greatly from that for worms in the sea. Worms living in small flowing seawater systems containing 16 cm3 of sediment accumulated 65Zn added to each system in the form of radioactive organic detritus. Higher percentage uptake of 65Zn was from radioactive detritus particles 0.2 to 2 mm in diameter resting on the sediment surface or mixed with sediment than from finely-ground (65Zn coprecipitated from fresh water with Fe(OH)3 was accumulated by N. diversicolor when the precipitate was on the sediment surface than when the precipitate was well mixed with the sediment. These experimental results indicate that benthic organisms may take up limited amounts of heavy metals associated with bottom sediments and recycle them to benthic and pelagic food webs

  1. Prediction of Persistent Organic Pollutants Biodegradation in Contaminated Marine Sediments Using Passive Sampling Probes

    OpenAIRE

    Prokofyev, E.; Frapiccini, E.; Marini, M.; Bondarenko, A.; Ruello, M.L.

    2014-01-01

    The aim of this study is to evaluate a new configuration (new materials) of the commercial passive sampler Chemcatcher as probe for predicting the bioavailability of persistent organic pollutants in marine sediments. To predict the availability of pollutants to biota, it is important to understand both solution- and solid-phase processes in the sediment, including the kinetics of pollutants release from its binding agent (ligand and/or particle). The present study examined the kinetic of deso...

  2. Arsenic in marine sediments from French Mediterranean ports: Geochemical partitioning, bioavailability and ecotoxicology

    OpenAIRE

    Mamindy-Pajany, Yannick; Hurel, Charlotte; Geret, Florence; Galgani, Francois; Battaglia-Brunet, Fabienne; Marmier, Nicolas; Romeo, Michele

    2013-01-01

    This work investigates arsenic mobility, bioavailability and toxicity in marine port sediments using chemical sequential extraction and laboratory toxicity tests. Sediment samples were collected from two different Mediterranean ports, one highly polluted with arsenic and other inorganic and organic pollutants (Estaque port (EST)), and the other one, less polluted, with a low arsenic content (Saint Mandrier port (SM)). Arsenic distribution in the solid phase was studied using a sequential extr...

  3. Uptake of plutonium from seawater and sediment by a marine polychaete worm

    International Nuclear Information System (INIS)

    The results of the uptake of plutonium 239 from sediment by a marine polychaete worm Nereis diversicolor is reported in the present paper. A comparison is made of the relative importance of two possible uptake pathways, sediment and seawater by which this worm may obtain its plutonium body-burden. Under the laboratory conditions used for the comparison of those two routes it would appear that Nereis obtained greater than 98% of its body activity from seawater. (auth.)

  4. Application of compositional data analysis to geochemical data of marine sediments

    OpenAIRE

    Burger, H.; Kuhn, T.

    2008-01-01

    In an earlier investigation (Burger et al., 2000) five sediment cores near the Rodrigues Triple Junction in the Indian Ocean were studied applying classical statistical methods (fuzzy c-means clustering, linear mixing model, principal component analysis) for the extraction of endmembers and evaluating the spatial and temporal variation of geochemical signals. Three main factors of sedimentation were expected by the marine geologists: a volcano-genetic, a hydro-hydrothermal and ...

  5. Radiometric dating of sediment records in Kuwait's marine area

    International Nuclear Information System (INIS)

    Six sediment cores collected from the Northwestern Arabian/Persian Gulf have been radiometrically dated by 210Pb. Three cores were collected from stations within the Kuwait Bay, and three others were collected from stations outside the bay. Two models have been used for 210Pb dating of sediment cores, i.e. Constant Flux: Constant Sedimentation (CF:CS) Model and the Constant Rate of Supply (CRS) Model. The average rates were found to vary significantly between 0.16 and 1.00 cm y-1 for stations outside and within the bay respectively. The variability of the sedimentation rate was essentially physiographic characteristics and variable hydrodynamic condition. In this study, 137Cs fallout radiotracer was also used to construct a realistic chronology. It was observed that the 137Cs in the entire vertical profile has been continuously contributed by fluvial and atmospheric deposition. (author)

  6. Evaluation of the toxicity of organic matter in marine sediments

    Digital Repository Service at National Institute of Oceanography (India)

    Sarkar, A.

    . The variation of the inhibition of AChE is attributed to the presence of the residues of various neurotoxic substances in the sediment contaminatEd. by the river runoff as well industrial effluents and sewage...

  7. Evaluation of the toxicity of organic matter in marine sediments

    Digital Repository Service at National Institute of Oceanography (India)

    Sarkar, A.

    . The variation of the inhibition of AChE is attributed to the presence of the residues of various neurotoxic substances in the sediment contaminatEd. by the river runoff as well industrial effluents and sewage....

  8. Additive modelling reveals spatiotemporal PCBs trends in marine sediments

    OpenAIRE

    G. EVERAERT; De Laender, F.; Deneudt, K.; Roose, P.; Mees, J.; Goethals, P.L.M.; Janssen, C.R.

    2014-01-01

    We developed generalised additive mixed models (GAMMs) to infer spatiotemporal trends of environmental PCB concentrations from an extensive dataset (n = 1219) of PCB concentrations measured between 1991 and 2010 in sediments of the Belgian Coastal Zone (BCZ) and the Western Scheldt estuary. A GAMM with time, geographical zone, periodicity and the organic carbon - water partition coefficient as covariates explained 49% of the variability in the log transformed PCB sediment concentrations. The ...

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

    Science.gov (United States)

    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

  10. Magnetic fingerprint in marine sediments: clues from cultivated Magnetovibrio blakemorei and recent cores from Brazilian Coast

    Science.gov (United States)

    Jovane, L.; Florindo, F.; Bazylinski, D. A.; Pellizari, V. H.; Brandini, F. P.; de Almeida, L. A.; Carneiro, F. R.; Braga, E. D.; Lins, U.

    2013-12-01

    The magnetic properties (first order reversal curves, ferromagnetic resonance and decomposition of saturation remanent magnetization acquisition) of Magnetovibrio blakemorei strain MV-1, a marine magnetotactic bacterium, differ from those of other magnetotactic species from sediments deposited in lakes and marine habitats previously studied. This finding suggests that magnetite produced by some magnetotactic bacteria retains magnetic properties in relation to the crystallographic structure of the magnetic phase produced and thus might represent a 'magnetic fingerprint' for a specific magnetotactic bacterium. The technique used to determine this fingerprint is a non-destructive, new technology that might allow for the identification and presence of specific species or types of magnetotactic bacteria in certain environments such as sediment. We also show some preliminary results on the biogeochemical factors that control magnetotactic bacterial populations, documenting the environment and the preservation of bacterial magnetite, which dominates the palaeomagnetic signal throughout recent sediments from Brazilian Coast. We searched for magnetotactic bacteria in order to understand the ecosystems and environmental change related to their presence in sediments. We focused on studying the environmental conditions that allow for the presence of magnetotactic bacteria and magnetosomes in sediments including determining magnetotactic bacterial populations in marine settings, measuring crucial nutrient availability in the water column and in sediments, and examining particulate delivery to the seafloor.

  11. Accumulation of heavy metals in sediments of marine environments along the southwest coast of India

    International Nuclear Information System (INIS)

    In order to estimate the rate of excessive sediment accumulation that causes navigational problems and the impacts of urban and industrial development on sediment quality, concentrations of Cu, Ni, Zn, Cr, Mn, Fe and Ca, and radioactivity levels of 210Pb and 137 Cs have been measured in nineteen sediment cores from estuarine, lagoonal, marsh, backwater and inner shelf areas along the southwest coast of India. Sediment accumulation rates in estuarine, lagoonal, marshy areas of the Karnataka coast (ELMKC) and Cochin Backwaters (CBw) are three to six times higher than those in the adjacent inner shelf areas, consistent with the deposition of terrigenous sediments in the river-sea interaction zones. Hydrogen sulphide was detected in most of the samples; sediment colour varied from shades of gray to dark green. Sediments have lower elemental concentrations and element enrichment factors (EFs) particularly for redox sensitive elements such as Mn due to prevalence of reducing conditions in the sedimentary column. Sediments of ELMKC and CBw have a predominantly terrigenous source. They contain low Ca contents, characteristic of tropical river sediments. In contrast, a higher Ca content of inner shelf sediments off both Karnataka State (ISKS-1) and Kerala State (ISKS-2) implies the importance of additional sediment (CaCO3) flux from the marine biota. Measured Cu, Ni and Zn concentrations are generally low, perhaps reflecting the pristine nature of sediments. However, higher concentrations of Cr at all stations and of Zn at CBw indicate the input of Cr enriched minerals like amphibole and pyroxene from the catchment as well as Zn from anthropogenic sources. Heavy metal accumulation rates are high in estuarine, lagoonal, marsh and backwater areas along the southwest coast of India. This is not only due to the proximity of sources, but also due to high sediment accumulation rates because of the reduction of river flow in river-sea interaction zones owing to particle

  12. Composite cement mortars based on marine sediments and oyster shell powder

    OpenAIRE

    Ez-zaki, H.; Diouri, A.; Kamali-Bernard, S.; Sassi, O.

    2016-01-01

    Additions of dredged marine sediments and oyster shell powder (OS) as cement substitute materials in mortars are examined by several techniques. The sediments have high water and chloride contents and calcite, quartz, illite and kaolinite as principal minerals. The OS powders are entirely composed of calcium carbonate and traces of other impurities. Four mixtures of treated sediments and OS powders at 650 °C and 850 °C are added to Portland cement at 8%, 16% and 33% by weight. The hydration o...

  13. Organic pollutants in sediment cores of NE-Germany: Comparison of the marine Arkona Basin with freshwater sediments

    International Nuclear Information System (INIS)

    During a contamination survey in NE-Germany sediment cores were sampled at 5 locations with freeze-coring devices and conventional box-coring systems. In total more than 40 samples were analysed for several organic compounds (136 PCDD/F, 33 PCB, 39 PAH, 10 DDX, 4 HCH, 4 CB), sedimentological parameters (TOC, TC, TIC, LOI), some total trace metals (Pb, Cd, Cr, Cu, Zn) and dated by measurement of the 21Pb and 137Cs activity. The deepest segment of the cores from the Arkona Basin and the freshwater lakes were dated back to the end of the 19th century. A comparison of marine versus freshwater data is presented. The contamination levels of Arkona Basin were often lower than anthropogenically influenced freshwater sediments and more similar to a freshwater sediment core only influenced by deposition, with an additional Oder River inflow. Differences in patterns and contamination levels are discussed

  14. Electrophoretic Extraction and Proteomic Characterization of Proteins Buried in Marine Sediments

    Directory of Open Access Journals (Sweden)

    Eli K. Moore

    2014-10-01

    Full Text Available Proteins are the largest defined molecular component of marine organic nitrogen, and hydrolysable amino acids, the building blocks of proteins, are important components of particulate nitrogen in marine sediments. In oceanic systems, the largest contributors are phytoplankton proteins, which have been tracked from newly produced bloom material through the water column to surface sediments in the Bering Sea, but it is not known if proteins buried deeper in sediment systems can be identified with confidence. Electrophoretic gel protein extraction methods followed by proteomic mass spectrometry and database searching were used as the methodology to identify buried phytoplankton proteins in sediments from the 8–10 cm section of a Bering Sea sediment core. More peptides and proteins were identified using an SDS-PAGE tube gel than a standard 1D flat gel or digesting the sediment directly with trypsin. The majority of proteins identified correlated to the marine diatom, Thalassiosira pseudonana, rather than bacterial protein sequences, indicating an algal source not only dominates the input, but also the preserved protein fraction. Abundant RuBisCO and fucoxanthin chlorophyll a/c binding proteins were identified, supporting algal sources of these proteins and reinforcing the proposed mechanisms that might protect proteins for long time periods. Some preserved peptides were identified in unexpected gel molecular weight ranges, indicating that some structural changes or charge alteration influenced the mobility of these products during electrophoresis isolation. Identifying buried photosystem proteins suggests that algal particulate matter is a significant fraction of the preserved organic carbon and nitrogen pools in marine sediments.

  15. Accumulation of polychlorinated organic contaminants from sediment by three benthic marine species

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. The use of ecocores to evaluate biodegradation in marine sediments

    DEFF Research Database (Denmark)

    Jensen, Kurt; Albrechtsen, Hans-Jørgen; Nielsen, Jef;

    1988-01-01

    A laboratory sediment microcosm called the ecocore is described. It has been used to test the biodegradability of substances which predominantly enter the sediment. A new method for introducing hydrophobic test substances such as hydrocarbons to the test system is also described. In a series of...... tests using 14C-labelled hydrocarbons, it has been demonstrated that evolved and trapped 14C02 in all probability reflects the rates of mineralization of the test substance. The fate of the substances within the test system has been described and the total recovery exceeds 80%. The system shows good...

  17. Long distance electron transport in marine sediments: Microbial and geochemical implications

    DEFF Research Database (Denmark)

    Risgaard-Petersen, Nils; Larsen, Steffen; Pfeffer, Christian;

    sulfate, and iron sulphides are the major sources for sulfide in the system. Procaryotes with the ability to perform long distance electron transmission may flourishes in marine sediments exposed to transient oxygen depletion, leaving distinct signatures of such events in the geological record....

  18. Thermodynamic and kinetic control on anaerobic oxidation of methane in marine sediments

    DEFF Research Database (Denmark)

    Knab, Nina J.; Dale, Andrew W.; Lettmann, Karsten;

    2008-01-01

    The free energy yield of microbial respiration reactions in anaerobic marine sediments must be sufficient to be conserved as biologically usable energy in the form of ATP. Anaerobic oxidation of methane (AOM) coupled to sulfate reduction (SRR) has a very low standard free energy yield of ΔG  = -3...

  19. Marine protist diversity in European coastal waters and sediments as revealed by high-throughput sequencing.

    Science.gov (United States)

    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. PMID:26119494

  20. usSEABED: Database Efforts in Marine Surficial Sediments of the US EEZ

    Science.gov (United States)

    Reid, J. A.; Jenkins, C. J.; Field, M. E.; Gardner, J. V.; Zimmermann, M.; Box, C. E.; Kneeshaw, T. A.

    2001-12-01

    The USGS, in partnership with the University of Sydney, Australia and National Marine Fisheries Service, Seattle is constructing a unique marine surficial sediment database, usSEABED, for the United States EEZ. usSEABED maximizes the knowledge of the seafloor by combining sedimentological and biological information, verbal sample and photographic descriptions (through fuzzy set theory), chemical, and acoustic data, along with other seabed geologic characteristics, into a single standardized format. In this way, usSEABED is more than a compilation of known quantitative surficial sediment data but rather provides an integrated view of the seabed. Decades of marine sediment research by federal, state, local, academic, and private institutions has provided temporal and spatial snapshots of the ocean floor, either as focused, tightly gridded sampling efforts, or in the earliest days, more widely scattered efforts. As is, these datasets had disparate purposes with dissimilar sampling parameters, statistics, and data types. usSEABED filters these datasets, providing uniform parameters for quantitative sediment textural data, parsed verbal data (using fuzzy set theory), modeled data, and both geologic and biologic compositional parameters. Access to our efforts is through our website, available in the fall of 2001, which includes an explanation of the processing involved, sample maps, an interactive GIS site, and a data-download site. usSEABED is held in a comma-delimited, field-defined, tree-d structure that can be brought into most COTS relational databases or GIS. Focussed originally on the U.S. Pacific margin, recent work is widening the coverage to areas in Hawaii, Alaska, the Gulf of Mexico, the Great Lakes, and the U.S. Atlantic margin. usSEABED is an ongoing project, with expanding data inclusions and new data-filtering modules available, such as sediment true-color displays and marine mineral locations. We invite the additions of new sedimentological, biological

  1. Bioaccumulation kinetics of polybrominated diphenyl ethers from estuarine sediments to the marine polychaete, Nereis virens.

    Science.gov (United States)

    Klosterhaus, Susan L; Dreis, Erin; Baker, Joel E

    2011-05-01

    Polybrominated diphenyl ethers (PBDEs) are flame-retardant chemicals that have become ubiquitous environmental contaminants. Polybrominated diphenyl ether no-uptake rates from estuarine or marine sediments to deposit-feeding organisms have not yet been reported. In the present study, the marine polychaete worm Nereis virens was exposed to field-contaminated and spiked sediments containing the penta- and deca-BDE commercial mixtures in a 28-d experiment to characterize the relative bioavailability of PBDE congeners from estuarine sediments. A time series sampling regimen was conducted to estimate uptake rate constants. In both field-collected and laboratory-spiked sediment exposures, worms selectively accumulated congeners in the penta-BDE mixture over BDE 209 and other components of the deca-BDE mixture, supporting the prevalence of these congeners in higher trophic level species. Brominated diphenyl ether 209 was not bioavailable to N. virens from field sediment and was only minimally detected in worms exposed to spiked sediments in which bioavailability was maximized. Chemical hydrophobicity was not a good predictor of bioavailability for congeners in the penta-BDE mixture. Direct comparison of bioavailability from the spiked and field sediments for the predominant congeners in the penta-BDE mixture was confounded by the considerable difference in exposure concentration between treatments. Biota-sediment accumulation factors (BSAFs) for N. virens after 28 d of exposure to the field sediment were lower than the BSAFs for Nereis succinea collected from the field site, indicating that 28-d bioaccumulation tests using N. virens may underestimate the in situ concentration of PBDEs in deposit-feeding species. The bioavailability of PBDEs to N. virens indicates that these chemicals can be remobilized from estuarine sediments and transferred to aquatic food webs. PMID:21337608

  2. Comparative study of plutonium and americium bioaccumulation from two marine sediments contaminated in the natural environment

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, T.F.; Smith, J.D. (Melbourne Univ., Parkville (Australia). Dept. of Inorganic Chemistry); Fowler, S.W.; LaRosa, J.; Holm, E. (International Atomic Energy Agency, Monaco-Ville (Monaco). Lab. of Marine Radioactivity); Aarkrog, A.; Dahlgaard, H. (Risoe National Lab., Roskilde (Denmark))

    1991-01-01

    Plutonium and americium sediment-animal transfer was studied under controlled laboratory conditions by exposure of the benthic polychaete Nereis diversicolor (O. F. Mueller) to marine sediments contaminated by a nuclear bomb accident (near Thule, Greenland) and nuclear weapons testing (Enewetak Atoll). In both sediment regimes, the bioavailability of plutonium and {sup 241}Am was low, with specific activity in the tissues <1% (dry wt) than in the sediments. Over the first three months, a slight preference in transfer of plutonium over {sup 241}Am occurred and {sup 241}Am uptake from the Thule sediment was enhanced compared to that from lagoon sediments of Enewetak Atoll. Autoradiography studies indicated the presence of hot particles of plutonium in the sediments. The results highlight the importance of purging animals of their gut contents in order to obtain accurate estimates of transuranic transfer from ingested sediments into tissue. It is further suggested that enhanced transuranic uptake by some benthic species could arise from ingestion of highly activity particles and organic-rich detritus present in the sediments. (author).

  3. Using marine sediment archives to reconstruct past outlet glacier variability

    DEFF Research Database (Denmark)

    Andresen, Camilla Snowman; Straneo, Fiamma; Ribergaard, Mads;

    2013-01-01

    Ice-rafted debris in fjord sediment cores provides information about outlet glacier activity beyond the instrumental time period. It tells us that the Helheim Glacier, Greenland’s third most productive glacier, responds rapidly to short-term (3 to 10 years) climate changes....

  4. Concretization of high level radioactive source in marine sediment

    International Nuclear Information System (INIS)

    A method is described of forming a concretized coating which encapsulates a canister of heat producing materials and provides protection against corrosion by seawater when the canister is placed in an ocean floor-sediment environment. The method comprises: selecting a location on the ocean floor at such a depth that the proximate seawater thereat would be capable of reaching a temperature of at least 1100C. when in contact with the canister of heat producing materials. The seawater within the pores of the ocean floor sediment thereat contains sufficient amounts of calcium and sulfate to form, at the temperature, an anhydrite layer around the canister; placing the canister into the ocean floor sediment at the location; and storing the canister at the location for at least one month thereby allowing heat from the canister to raise the temperature of the seawater in the pores of the sediment proximate to the canister to at least 1100C. wherein anhydrite precipitates from the proximate seawater and forms a concretized layer on the exterior surfaces of the canister

  5. Development and Evaluation of Polychaete Reverse Samplers for Marine Phase II Whole Sediment Toxicitiy Identification Evaluations (TIE)

    Science.gov (United States)

    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...

  6. Imaging Oxygen Distribution in Marine Sediments. The Importance of Bioturbation and Sediment Heterogeneity

    OpenAIRE

    Pischedda, Laura; Poggiale, Jean-Christophe; Cuny, Philippe; Gilbert, Franck

    2008-01-01

    The influence of sediment oxygen heterogeneity, due to bioturbation, on diffusive oxygen flux was investigated. Laboratory experiments were carried out with 3 macrobenthic species presenting different bioturbation behaviour patterns:the polychaetes Nereis diversicolor and Nereis virens, both constructing ventilated galleries in the sediment column, and the gastropod Cyclope neritea, a burrowing species which does not build any structure. Oxygen two-dimensional distribution in sediments was qu...

  7. Optimization of hard clams, polychaetes, physical disturbance and denitrifying bacteria of removing nutrients in marine sediment.

    Science.gov (United States)

    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

  8. Instrumental neutron activation analysis of marine sediment in-house reference material

    International Nuclear Information System (INIS)

    Reference materials play an important role in demonstrating the quality and reliability of analytical data. The advantage of using in-house reference materials is that they provide a relatively cheap option as compared to using commercially available certified reference material (CRM) and can closely resemble the laboratory routine test sample. A marine sediment sample was designed as an in-house reference material, in the framework of quality assurance and control (QA/QC) program of the Neutron Activation Analysis (NAA) Laboratory at Nuclear Malaysia. The NAA technique was solely used for the homogeneity test of the marine sediment sample. The CRM of IAEA- Soil 7 and IAEA- SL1 (Lake Sediment) were applied in the analysis as compatible matrix based reference materials for QA purposes. (Author)

  9. Validation of an analytical methodology for the quantitative analysis of petroleum hydrocarbons in marine sediment samples

    Directory of Open Access Journals (Sweden)

    Eloy Yordad Companioni Damas

    2009-01-01

    Full Text Available This work describes a validation of an analytical procedure for the analysis of petroleum hydrocarbons in marine sediment samples. The proposed protocol is able to measure n-alkanes and polycyclic aromatic hydrocarbons (PAH in samples at concentrations as low as 30 ng/g, with a precision better than 15% for most of analytes. The extraction efficiency of fortified sediments varied from 65.1 to 105.6% and 59.7 to 97.8%, for n-alkanes and PAH in the ranges: C16 - C32 and fluoranthene - benzo(apyrene, respectively. The analytical protocol was applied to determine petroleum hydrocarbons in sediments collected from a marine coastal zone.

  10. Sequential Sediment Budgets in an Ungauged Watershed: Redwood Creek, Marin County, California

    Science.gov (United States)

    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

  11. Sedimentation rates and age modeling of Late Quaternary marine sediments with unsupported 230Th

    International Nuclear Information System (INIS)

    230Th is a radionuclide of the 238U decay series, characterized by natural abundance in sediments and a half-life of 75,380 years, suitable for direct evaluation of sedimentation rates and sediment ages in a time scale of 700,000 years before the present. 230Th cycle creates a contrast between supported and unsupported 230Th in the sedimentary matrix due to the different geochemical behaviors of 230Th and its parent, 234U. This study aimed at establishing and validating a mathematical model that evaluates sedimentation rates and age modeling based on 230Th data retrieved from a sediment core sampled in the southeastern Brazilian continental margin. The validation of the age modeling of this method was made through a statistical comparison between its results and those of benthic foraminifera δ 18O record technique, widely used for sediment dating and determination of sedimentation rates. It was observed that the model of unsupported 230Th was successful in determining Late Quaternary sedimentation rates and ages in a confidence level of 95 %. It was possible to determine several breaking points in unsupported 230Th vertical profile, and it was shown that those divides correspond to some major intervals between glacial and interglacial periods when compared with the benthic foraminifera record. (author)

  12. Study of photocatalytic degradation of tributyltin, dibutylin and monobutyltin in water and marine sediments.

    Science.gov (United States)

    Brosillon, Stephan; Bancon-Montigny, Chrystelle; Mendret, Julie

    2014-08-01

    This study reports on the first assessment of the treatment of sediments contaminated by organotin compounds using heterogeneous photocatalysis. Photocatalysis of organotins in water was carried out under realistic concentration conditions (μgL(-1)). Degradation compounds were analyzed by GC-ICP-MS; a quasi-complete degradation of tributyltin (TBT) in water (99.8%) was achieved after 30min of photocatalytic treatment. The degradation by photolysis was about (10%) in the same conditions. For the first time decontamination of highly polluted marine sediments (certified reference material and harbor sediments) by photocatalysis proves that the use of UV and the production of hydroxyl radicals are an efficient way to treat organotins adsorbed onto marine sediment despite the complexity of the matrix. In sediment, TBT degradation yield ranged from 32% to 37% after only 2h of irradiation (TiO2-UV) and the by-products: dibutyltin (DBT) and monobutyltin (MBT) were degraded very rapidly in comparison with TBT. It was shown that during photocatalysis of organotins in sediments, the hydroxyl radical attack and photolysis are the two ways for the degradation of adsorbed TBT. PMID:24613444

  13. Recent surface marine sediments of Cocos Island in Costa Rica

    Institute of Scientific and Technical Information of China (English)

    Jeffrey A. SIBAJA-CORDERO; Jess S. TRONCOSO; Eddy GMEZ-RAMREZ

    2014-01-01

    Subtidal sediments of Isla del Coco (Cocos Island), Costa Rica were described in their grain size, sorting, organic matter, and carbonates from 27 dredge samples (3-75 m), collected in April 2010. The organic matter range between 1.37-3.31% and carbonates presented a mean of 74±17%. The sorting was moderately or poorly. The grain size ranged between 0.1-1.1mm. The pattern is that sediment change from inner to mouth of bays. Carbonates and gravel fractions increased offshore and organic matter have high values inner the bays. Input of vegetal debris and mud was from the rivers of this island covered with rain and cloud forest.

  14. TEX86 paleothermometry : proxy validation and application in marine sediments

    OpenAIRE

    C. Huguet

    2007-01-01

    Determination of past sea surface temperature (SST) is of primary importance for the reconstruction of natural climatic changes, modelling of climate and reconstruction of ocean circulation. Recently, a new SST proxy was introduced, the TetraEther indeX of lipids with 86 carbons (TEX86), which is based on temperature-related changes that occur in the composition of creanarchaeotal membrane lipids. An empirical correlation between TEX86 values of sediment core tops from a wide variety of geogr...

  15. Diagenetic imprints on magnetic mineral assemblages in marine sediments

    OpenAIRE

    Garming, Johanna Fredrika Lukina

    2006-01-01

    Sediments and sedimentary rocks are important sources for paleomagnetic studies of the geomagnetic field behaviour and of environmental changes. These studies are greatly dependent on the reliable extraction of the detrital magnetic signal. Overprinting of this signal by reductive diagenetic processes, where iron-bearing minerals are dissolved and secondary (magnetic) sulphide minerals form, jeopardizes the validity of such investigations. It is therefore necessary to be aware of the possible...

  16. The carbon isotope biogeochemistry of acetate from a methanogenic marine sediment

    Science.gov (United States)

    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.

  17. Toxicological effects of short-term resuspension of metal-contaminated freshwater and marine sediments.

    Science.gov (United States)

    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 (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. PMID:26313755

  18. Using marine bioassays to classify the toxicity of Dutch harbor sediments.

    Science.gov (United States)

    Stronkhorst, Joost; Schipper, Cor; Brils, Jos; Dubbeldam, Marco; Postma, Jaap; van de Hoeven, Nelly

    2003-07-01

    A procedure was developed to assess contaminated marine sediments from Dutch harbors for possible adverse biological effects using three laboratory bioassays: A 10-d survival test with the amphipod Corophium volutator, a 14-d survival test with the heart urchin Echinocardium cordatum (adults), and the bioluminescence inhibition test with the bacterium Vibrio fischeri (Microtox solid phase test LSP]). Microtox results were mathematically corrected for the modifying influence of fine sediment particles. After a validation procedure on test performance and modifying factors, respectively, 81%, 99%, and 90% of the amphipod, heart urchin, and Microtox results were approved. Lower and upper threshold limits for biological effects were set at respectively 24 and 30% mortality for C. volutator, 27 and 35% mortality for E. cordatum, and 24 and 48 toxic units for the Microtox SP based on significant differences with control sediment and the performance of reference sediments. The bioassays clearly distinguished harbor sediments that give rise to acute effects and those that do not. Threshold limits for the amphipods, heart urchins, and bacteria were exceeded in, respectively, 9 to 17%, 33 to 40%, and 23 to 50% of the sediment samples. Highest effects were observed in sediments from the northerly harbors; there was significantly less response in sediments from the Delta Region and the port of Rotterdam (The Netherlands). The procedure outlined in this paper can be used for routine screening of contaminated dredged material that is proposed for open water disposal. PMID:12836979

  19. Imaging oxygen distribution in marine sediments. The importance of bioturbation and sediment heterogeneity.

    Science.gov (United States)

    Pischedda, L; Poggiale, J C; Cuny, P; Gilbert, F

    2008-06-01

    The influence of sediment oxygen heterogeneity, due to bioturbation, on diffusive oxygen flux was investigated. Laboratory experiments were carried out with 3 macrobenthic species presenting different bioturbation behaviour patterns: the polychaetes Nereis diversicolor and Nereis virens, both constructing ventilated galleries in the sediment column, and the gastropod Cyclope neritea, a burrowing species which does not build any structure. Oxygen two-dimensional distribution in sediments was quantified by means of the optical planar optode technique. Diffusive oxygen fluxes (mean and integrated) and a variability index were calculated on the captured oxygen images. All species increased sediment oxygen heterogeneity compared to the controls without animals. This was particularly noticeable with the polychaetes because of the construction of more or less complex burrows. Integrated diffusive oxygen flux increased with oxygen heterogeneity due to the production of interface available for solute exchanges between overlying water and sediments. This work shows that sediment heterogeneity is an important feature of the control of oxygen exchanges at the sediment-water interface. PMID:18247133

  20. Uranium and plutonium in marine sediments; Uranio y plutonio en sedimentos marinos

    Energy Technology Data Exchange (ETDEWEB)

    Ordonez R, E.; Almazan T, M. G. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Ruiz F, A. C., E-mail: eduardo.ordonez@inin.gob.mx [UNAM, Instituto de Ciencias del Mar y Limnologia, Unidad Academica Mazatlan, Sinaloa (MX)

    2011-11-15

    The marine sediments contain uranium concentrations that are considered normal, since the seawater contains dissolved natural uranium that is deposited in the bed sea in form of sediments by physical-chemistry and bio-genetics processes. Since the natural uranium is constituted of several isotopes, the analysis of the isotopic relationship {sup 234}U/{sup 238}U are an indicator of the oceanic activity that goes accumulating slowly leaving a historical registration of the marine events through the profile of the marine soil. But the uranium is not the only radioelement present in the marine sediments. In the most superficial strata the presence of the {sup 239+140}Pu has been detected that it is an alpha emitter and that recently it has been detected with more frequency in some coasts of the world. The Mexican coast has not been the exception to this phenomenon and in this work the presence of {sup 239-140}Pu is shown in the more superficial layers of an exploring coming from the Gulf of Tehuantepec. (Author)

  1. Biogeomorphological implications of microscale interactions between sediment geotechnics and marine benthos: a review

    Science.gov (United States)

    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.

  2. Environmental and biogeochemical process of accumulation of iron-phosphorus in marine sediments

    Institute of Scientific and Technical Information of China (English)

    WENG Huanxin; ZHANG Xingmao; WU Nengyou; CHEN Lihong; CHEN Jingfeng; WANG Ying; QIN Yachao; TIAN Rongxiang

    2004-01-01

    This paper discusses the environmental and biogeochemical process of accumulation of iron-phosphorus in marine sediments for the north aktian of the South China Sea and analyzes the relationships between the contents of iron, phosphorus and calcium carbonate as well as their existent characteristics. The results show that the variances of phosphorus and calcium carbonate contents with depths are opposite and those of iron and calcium carbonate contents are almost accordant. It is not only related to the biogeochemical process of accumulation of biogenous calcium carbonate in sediments, which resulted from the fact that the marine primary productivity was stimulated by part of terrigenous phosphorus dissolved into seawater due to decline of superficial water temperature and increase of carbon dioxide content in the glacial period, but also related to iron impelled oxidation and accelerated deposit by the dissolved oxygen from the atmosphere and the photosynthesis of hydrophytes in seawater. The variance of soluble iron-phos- phorus species (Fe-P) in sediment columns can sensitively reflect the changes of climate and environment, which suggests that the accumulative characteristics and existent states of iron-phosphorus species (Fe-P) in marine sediments have the significance as an indicator of the changes of paleoclimate and paleoenvironment.

  3. Origin, dynamics, and implications of extracellular DNA pools in marine sediments.

    Science.gov (United States)

    Torti, Andrea; Lever, Mark Alexander; Jørgensen, Bo Barker

    2015-12-01

    In marine sediments, DNA occurs both inside and outside living organisms. DNA not enclosed in living cells may account for the largest fraction of total DNA, and include molecules locked within dead cells, organic and inorganic aggregates, adsorbed onto mineral matrices, and viral DNA. This DNA comprises genetic material released in situ from sediment microbial communities, as well as DNA of pelagic and terrestrial origin deposited to the seafloor. DNA not enclosed in living cells undermines the assumption of a direct link between the overall DNA pool and the local, currently living microbial assemblages, in terms of both microbial cell abundance and diversity. At the same time, the extracellular DNA may provide an integrated view of the biodiversity and ecological processes occurring on land, in marine water columns, and sediments themselves, thereby acting as an archive of genetic information which can be used to reconstruct past changes in source environments. In this review, we identify and discuss DNA pools in marine sediments, with special focus on DNA not enclosed in living cells, its origin, dynamics, and ecological and methodological implications. Achievements in deciphering the genetic information held within each DNA pool are presented along with still-standing challenges and major gaps in current knowledge. PMID:26452301

  4. Geochemical analysis of marine sediments using fused glass disc by X-ray fluorescence spectrometry

    Institute of Scientific and Technical Information of China (English)

    XIA Ning; ZHANG Qin; YAO De; LI Guohui

    2008-01-01

    A method was developed for content determination of Na, Mg, Al, Si, P,S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Nb, Zr, Y, Sr, Rb, Ba, La and Ce etc. covering 26 major, minor, and trace elements in marine sediment samples using fused glass disc by X-ray Fluorescence spectrometry. Calibration was made using marine sediment certified reference materials and the synthetic standard samples prepared by mixing several marine sediments with stream sediment and carbonate standard samples in different proportions. The matrix effect was corrected using theoretical alpha coefficients, experience coefficients and the scattered radiation as the internal standard (for the trace elements). The accuracy of the method was evaluated by analysis of certified reference materials GBW07314, GBW07334 and GSMS6. The results are in good agreement with the certified values of the standards with RSD less than 2.60%, except for Y, Cr, Ga, Ce, La, Nb, Rb, and V with RSD less than 9.0% (n=12).

  5. Thermophilic anaerobes in arctic marine sediments induced to mineralize complex organic matter at high temperature

    DEFF Research Database (Denmark)

    Hubert, Casey; Arnosti, Carol; Brüchert, Volker;

    2010-01-01

    well as with the addition of freeze-dried Spirulina or individual high-molecular-weight polysaccharides. During 50°C incubation experiments, Arctic thermophiles catalysed extensive mineralization of the organic matter via extracellular enzymatic hydrolysis, fermentation and sulfate reduction. This high...... temperature-induced food chain mirrors sediment microbial processes occurring at cold in situ temperatures (near 0°C), yet it is catalysed by a completely different set of microorganisms. Using sulfate reduction rates (SRR) as a proxy for organic matter mineralization showed that differences in organic matter......Marine sediments harbour diverse populations of dormant thermophilic bacterial spores that become active in sediment incubation experiments at much higher than in situ temperature. This response was investigated in the presence of natural complex organic matter in sediments of two Arctic fjords, as...

  6. Physical chemical analysis of marine sediment cementation from the Gulf of Guinea

    Science.gov (United States)

    Liu, Xianfeng; Hammad, Tammam; Saiyouri, Nadia; Hattab, Mahdia

    2012-09-01

    This study aims at investigating the cementation of marine sediments from the Gulf of Guinea by using physicochemical analysis. In order to highlight the presence of cementation in the sediments, three conventional consolidation tests were conducted on intact and remoulded samples. Mercury intrusion porosimetry analyses were then carried out on the specimens taken from samples after consolidation tests. Several physicochemical experimental techniques were used to analyze these cementations, such as cation exchange capacity analysis, batch test, scanning electron microscope imaging coupled with EDS chemical analysis, and thermal analysis. The results seem to indicate that the cementation of these sediments is predominated by the presence of smectite gel between clay aggregates (clusters). Finally, a conceptual sediment microstructural model is proposed to describe the cementation.

  7. Radiological assessment of coastal marine sediment and water samples, Karachi coast, Pakistan

    International Nuclear Information System (INIS)

    Concentrations of selective natural radionuclides (/sup 226/Ra, /sup 228/Ra, /sup 40/K) in shallow marine coastal sediments and sea water off Karachi coast, Pakistan, were measured with a hyper pure germanium (HPGe) gamma spectrometer. Sediment and water samples were collected from polluted Layari and Malire River downstream (pre-out fall), Gizri Creek, Layari River out fall in Karachi harbor, Karachi Harbor/ Manora Channel Mains, as well as from open sea (South-East Coast and North-West Coast) within the 10m depth contour. No artificial radionuclides (e.g. /sup 60/Co, /sup 137/Cs and /sup 134/Cs were detected in both water and sediment samples at any of these locations. The activity of /sup 226/Ra in coastal river sediments is found below its limit of detection (<18.35 Bqkg/sup -1/). Activity of /sup 228/Ra in sediments off Karachi Coast ranges between 11.80 +- 3.60 to 37.27+- 4.31 Bqkg/sup -1/. The highest activity was found south of Nuclear Power Station (KANUPP) and the lowest activity was found in the vicinity of Oyster Rocks (open sea). The /sup 226/Ra activity ranges from 19.40+- 5.88 to 67.14 +- 10.02 Bqkg/sup -1/. The activity of /sup 228/Ra in sediments of Manora Channel, South-east Coast of Karachi and the North west coast of Karachi are also in agreement with the IAEA marine sediment standard namely: IAEA-135 (/sup 228/Ra = 36.7 +- 3 Bqkg/sup -1/). The activity of /sup 226/Ra for the South East Coast of Karachi and the North west coast of Karachi are also in agreement with the IAEA marine sediment standard namely: IAEA 135(/sup 226/Ra=23.9 +- 1.1 Bqkg/sup -1/) and Pacific Ocean sediment standard namely: IAEA-368 (/sup 226/Ra=21.4+- 1.1 Bqkg/sup -1/). The /sup 40/K activity in sea sediments varies from 197.7+- 44.24 to 941.90 +- 39.00 Bqkg-1). The highest activity is observed in the vicinity of Oyster Rocks (open sea) along the Clifton coast (South-East Cost of Karachi) and the lowest activity is found south of Nuclear Power Station (KANUPP) along the

  8. Cultivation of Autotrophic Ammonia-Oxidizing Archaea from Marine Sediments in Coculture with Sulfur-Oxidizing Bacteria▿ †

    OpenAIRE

    Park, Byoung-Joon; Park, Soo-Je; Yoon, Dae-No; Schouten, Stefan; Sinninghe Damsté, Jaap S.; Rhee, Sung-Keun

    2010-01-01

    The role of ammonia-oxidizing archaea (AOA) in nitrogen cycling in marine sediments remains poorly characterized. In this study, we enriched and characterized AOA from marine sediments. Group I.1a crenarchaea closely related to those identified in marine sediments and “Candidatus Nitrosopumilus maritimus” (99.1 and 94.9% 16S rRNA and amoA gene sequence identities to the latter, respectively) were substantially enriched by coculture with sulfur-oxidizing bacteria (SOB). The selective enrichmen...

  9. Intercomparison of radionuclide measurements in marine sediment sample IAEA-367

    International Nuclear Information System (INIS)

    The results of an intercomparison exercise on a Pacific Ocean sediment sample, IAEA-367, designed for the determination of artificial and natural radionuclides levels, are reported. The data from 81 laboratories representing 37 countries have been evaluated. The following are the recommended values, with confidence intervals, for 60Co, 90Sr, 137Cs, 239+240Pu (Reference date: 1 January 1990). Information values for 155Eu, 238Pu, 241Am, and 241Pu are reported. Information values for the following natural radionuclides 40K, 226Ra, 228Th, 230Th, 234U, 235U and 238U are also reported. (author)

  10. Intercomparison of radionuclide measurements in marine sediment sample IAEA-368

    International Nuclear Information System (INIS)

    The results of an intercomparison exercise on a Pacific Ocean sediment sample, IAEA-368, designed for the determination of artificial and natural radionuclides levels, are reported. The data from 89 laboratories representing 37 countries have been evaluated. The following are the recommended values, with confidence intervals, for 60Co, 155Eu, 2107Pb, 226Ra, 238U, 238Pu and239+240Pu (Reference date: 1 January 1990). Information values for 40K, 90Sr, 137Cs, 228Th, 230Th, 232Th, 234U, 235U and 241Am are also reported. (author)

  11. Worldwide Interlaboratory Comparison on the Determination of Trace Elements in the IAEA-457 Marine Sediment Sample

    International Nuclear Information System (INIS)

    The primary goal of the IAEA Environment Laboratories is to assist Member States in the use of both stable and radioisotope analytical techniques to understand, monitor and protect the environment. In this context, the major impact of large coastal cities on marine ecosystems is an issue of primary concern for the IAEA and the IAEA Environment Laboratories. The marine pollution assessments required to understand such impacts depend on accurate knowledge of contaminant concentrations in various environmental compartments. Through the IAEA Environment Laboratories, the IAEA has been assisting national laboratories and regional laboratory networks since the early 1970s through the provision of a reference material programme for the analysis of radionuclides, trace elements and organic compounds in marine samples. Quality assurance and quality control are two fundamental requirements to ensure the reliability of analytical results. Data that are not based on adequate quality assurance and quality control can be erroneous, and their misuse can lead to poor environmental management decisions. In this regard, the IAEA has a long history of organizing interlaboratory studies, which have evolved to include an increasing array of potential contaminants in the marine environment. Relevant activities comprise global interlaboratory comparison, regional proficiency tests, the production of marine reference materials and the development of reference methods for trace elements and organic pollutants analysis in marine samples. This publication summarizes the results of the IAEA-457 interlaboratory comparison on the determination of trace elements in a marine sediment sample

  12. Magnetotactic bacteria in marine sediments: clues from recent cores from Brazilian Coast

    Science.gov (United States)

    Jovane, L.; Pellizari, V. H.; Brandini, F. P.; Braga, E. D. S.; Freitas, G. R.; Benites, M.; Rodelli, D.; Giorgioni, M.; Iacoviello, F.; Ruffato, D. G.; Lins, U.

    2014-12-01

    The magnetic properties (first order reversal curves, ferromagnetic resonance and decomposition of saturation remanent magnetization acquisition) of marine magnetotactic bacteria, in conjunction with geophysical, geochemical and oceanographic data from the Brazilian Coast, provide interesting insights regarding the primary productivity distribution in oceans. This finding suggests that magnetite produced by some magnetotactic bacteria retains magnetic properties in relation to the crystallographic structure of the magnetic phase produced and thus might represent a "magnetic fingerprint" for the presence of magnetotactic bacteria. The use of those magnetic properties is a non-destructive, new technology that might allow for the identification and presence of specific species or types of magnetotactic bacteria in certain environments such as sediment. We will also show some preliminary results on the biogeochemical factors that control magnetotactic bacterial populations, documenting the environment and the preservation of bacterial magnetite, which dominates the palaeomagnetic signal throughout recent sediments from Brazilian Coast. We searched for magnetotactic bacteria in order to understand the ecosystems and environmental change related to their presence in sediments. We studied magnetotactic bacterial concentration and geophysical, geochemical and oceanographic results in marine settings measuring crucially nutrients availability in the water column and in sediments, on particulate delivery to the seafloor, to understand the environmental condition that allow the presence of magnetotactic bacteria and magnetosomes in sediments.

  13. Exposure of the marine deposit feeder Hydrobia ulvae to sediment associated LAS

    Energy Technology Data Exchange (ETDEWEB)

    Mauffret, A., E-mail: aourell.mauffret@icman.csic.e [Marine Sciences Institute of Andalusia (CSIC), Puerto Real (Cadiz) (Spain); Rico-Rico, A. [Institute for Risk Assessment Sciences, Utrecht University (Netherlands); Temara, A. [The Procter and Gamble Company, Brussels (Belgium); Blasco, J. [Marine Sciences Institute of Andalusia (CSIC), Puerto Real (Cadiz) (Spain)

    2010-02-15

    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. - Lethality of the marine gastropod deposit feeder Hydrobia ulvae exposed to LAS in water-only system was inappropriate to predict LAS toxicity in sediment system.

  14. Sediment Ksub(d)s and concentration factors for radionuclides in the marine environment

    International Nuclear Information System (INIS)

    Both the biological and geochemical processes, which are dependent on the chemical form of the element in question, and the radioactive decay of the nuclide are important parameters in the models used for the calculation of dumping limits for radioactive wastes disposed of in the deep sea. The geochemical processes were not adequately represented in earlier models and only rough approximations of parameters were used in the calculations. This report provides an approach for the calculation of deep-sea sediment distribution coefficients and coastal sediment concentration factors for radionuclides in marine biological materials based, whenever possible, on field data

  15. Validation of an analytical methodology for the quantitative analysis of petroleum hydrocarbons in marine sediment samples

    OpenAIRE

    Eloy Yordad Companioni Damas; Miriam Odette Cora Medina; Ana Catalina Núñez Clemente; Miguel Ángel Díaz Díaz; Luis González Bravo; Rolando Marbot Ramada; Rodny Montes de Oca Porto

    2009-01-01

    This work describes a validation of an analytical procedure for the analysis of petroleum hydrocarbons in marine sediment samples. The proposed protocol is able to measure n-alkanes and polycyclic aromatic hydrocarbons (PAH) in samples at concentrations as low as 30 ng/g, with a precision better than 15% for most of analytes. The extraction efficiency of fortified sediments varied from 65.1 to 105.6% and 59.7 to 97.8%, for n-alkanes and PAH in the ranges: C16 - C32 and fluoranthene - benzo(a)...

  16. Biogeochemical Interactions In The Application Of Biotechnological Strategies To Marine Sediments Contaminated With Metals

    Directory of Open Access Journals (Sweden)

    Fonti Viviana

    2015-06-01

    Full Text Available Sediment contamination in coastal areas with high anthropogenic pressure is a widespread environmental problem. Metal contaminants are of particular concern, since they are persistent and cannot be degraded. Microorganisms can influence metal mobility in the sediment by several direct and indirect processes. However, the actual fate of metals in the environment is not easily predictable and several biogeochemical constraints affect their behaviour. In addition, the geochemical characteristics of the sediment play an important role and the general assumptions for soils or freshwater sediments cannot be extended to marine sediments. In this paper we analysed the correlation between metal mobility and main geochemical properties of the sediment. Although the prediction of metal fate in sediment environment, both for ex-situ bioleaching treatments and in-situ biostimulation strategies, appears to require metal-specific and site-specific tools, we found that TOM and pH are likely the main variables in describing and predicting Zn behaviour. Arsenic solubilisation/increase in mobility appears to correlate positively with carbonate content. Cd, Pb and Ni appear to require multivariate and/or non-linear approaches.

  17. Bioavailability of tetra- and hexa-chlorobiphenyls to benthic organisms from marine sediments

    International Nuclear Information System (INIS)

    Benthic animals (Nephtys incisa and Voldia limatula) were exposed to marine sediments which had been spiked with C-14 labelled tetra- (TPCB) or hexa-(HPCB) chlorobiphenyl and equilibrated for periods up to one month. The sediments and organisms were collected at various time intervals and analyzed for their PCB content by liquid scintillation counting following extraction with acetonitrile. The organic carbon content of the sediments and the lipid content of the animals was also determined. Changes in the body burdens of TPCB and HPCB were rapid during the first ten to twenty days of accumulation and tended to level off after thirty days. Accumulation rates were more rapid for the TPCB than for HPCB. Both the rate of accumulation and the apparent steady-state concentrations of PCBs were influenced by the organic carbon content of the sediments. Lipid normalized concentrations of both PCBs appeared to reach steady-state more rapidly than the whole-body concentrations. Preference factors (PF animal/sediment ratios) calculated for these sediments suggest that PF may not be independent of sediment organic carbon content

  18. Sediment-worm interactions: transfer of 65Zn, 109Cd and sup(110m)Ag from marine sediment by Nereis diversicolor

    International Nuclear Information System (INIS)

    Radiotracer experiments to understand the role of benthic worms in transferring 65Zn, 109Cd and sup(110m)Ag from marine sediments to marine food webs are described. Sediments were made radioactive by adding 30 to 50μCi of the appropriate high specific activity isotope to 500 ml of sea water and mixing with 100 cm3 of sediment. The 65Zn and 109Cd were added as chlorides and the sup(110m)Ag was added as nitrate. Relative accumulation from radioactive sediments and the loss rates of the metals from N. diversicolor were determined at different time intervals. Radioactive worms were transferred to fresh sediments and were periodically radioanalysed. It was observed that simple ingestion of subsurface radioactive sediments is a less effective route of Zn transfer to the worm than by deposit feeding at the sediment-water interface. Cadmium appears to be much less tightly bound to marine sediment than zinc. Worms which accumulated sup(110m)Ag from sediment during a 20 day exposure lost it at a faster rate than 65Zn accumulated during a 5 day exposure

  19. Corrosion of carbon steel nuclear waste containers in marine sediment

    International Nuclear Information System (INIS)

    The report describes a study of the corrosion of carbon steel nuclear waste containers in deep ocean sediments, which had the objective of estimating the metal allowance needed to ensure that the containers were not breached by corrosion for 1000 years. It was concluded that under such disposal conditions carbon steel would not be subject to localised corrosion or hydrogen embrittlement, and therefore the study concentrated on evaluating the rate of general attack. This was carried out by developing a mechanistically based mathematical model which was formulated on the conservative assumption that the corrosion would be under activation control, and would not be impeded by the formation of corrosion product layers. This model predicted that an allowance of 33 mm would be required for a 1000 year life. (author)

  20. Intercomparison of radionuclide measurements on marine sediment sample IAEA-300

    International Nuclear Information System (INIS)

    The results of an intercomparison exercise on a sediment from Baltic Sea, IAEA-300, designed for the determination of artificial and natural radionuclides' levels, are reported. The data from 159 laboratories representing 51 countries have been evaluated. The following are the recommended values, with confidence intervals, 40K, 60Co, 125Sb, 134Cs, 137Cs, 155Eu, 210Pb, 210Po, 228Ra, 234U, 238U, 239+240Pu and 241Am. Information values for 54Mn, 90Sr, 226Ra, 228Th, 230Th, 232Th, 235U and 238Pu are also reported. All values are given on the reference date of 1 January 1993 and expressed in Bq kg-1 dry weight. (author)

  1. Hyoscyamine-producing marine Actinomycetes from Lagos Lagoon sediment

    Institute of Scientific and Technical Information of China (English)

    Davies; Olabisi; Flora; Adeleye; Isaac; Adeyemi; Wang; Peng; George

    2015-01-01

    Objective:To isolate and screen Actinoniycetes from Lagos Lagoon soil sediments for production of bioactive metabolites.Methods:Sediment samples were collected from four different locations of Lagos Lagoon and were dried for 2 weeks after which the Actinoniycetes were isolated by serial dilution using the spread plate method on starch casein and Kuster’s agar supplemented with 80 ug/mL cycloheximide to prevent fungal growth.The plates were incubated at 28 C for 1-2 weeks.Isolates were selected based on their colonial characteristics as well as their Gram’s reaction and subciiltured using the same media for isolation until pure cultures were obtained and incubated at 28 C for 3 d.Thereafter,they were inoculated into starch casein and Kuster’s broth media and incubated for 8 d.The secondary metabolites were screened for antimicrobial activity against the following microorganisms:methicillin resistant Staphylococcus aureus.Staphylococcus aureus ATCC 29213.Escherichia coli ATCC 29522.Pseudomonas aeruginosa ATCC 27853.Candida albicans and Enterocolitis faecal is ATCC 29212.Coagulasenegative staphylococci isolated from HIV patients were also used(Staphylococcus warneri.Staphylococcus xylosus and Staphylococcus epidennidis).The antimicrobial metabolites of the Actinoniycetes isolates were identified using gas chromatography(GC).Results:Crude extracts of isolates showed antimicrobial activity against some of the test organisms.The GC data analysis showed the antibiotic profile of these isolates.Conclusions:Analysis of the crude extracts of the isolates using GC method,revealed the presence of antibiotics including an anticholinergic hyoscyamine among other conclusions.

  2. Denitrification and Nitrate Reduction to Ammonium in Taihu Lake and Yellow sea Inter—Tidal Marine Sediments

    Institute of Scientific and Technical Information of China (English)

    YINSHIXUE; SHENQIRONG; 等

    1999-01-01

    Denitrification and nitrate reduction to ammonium in Taihu Lake and Yellow Sea inter-tidal marine sediments were studied.The sediment samples were made slurry containing 150g dry matter per liter.Various of glucose-C to nitrate-N.Acetylene inhibition technique was applied to measure denitrification in the slurres,All samples were incubated anaerobically under argon atmosphere,Data showed that Taihu Lake sediment produced more N2O than marine sediment,Denitrification potential was higher in Taihu Lake sediment than in marine one,Glucose added increase denitrification activity but not the denitrification potential of the sediments.Dissimilatory nitrate reduction to ammonium seemed to occur in marine sediment,but not in freshwater one.When the marine sediment was treated with 25mmol L-1 glucose,its denitrification potentail,as indicated by maximum N2O production by acetylene blockage,was lower than that treated with no or 2.5mmol L-1 glucose.Acetylene was suspected to have inhibitory effect on dissimilatory nitrate reduction to ammonium.

  3. Validation of a method to measure plutonium levels in marine sediments in Cuba

    International Nuclear Information System (INIS)

    The main objective of this research was to develop and to validate a method of radiochemical separation of plutonium, suitable from the economic and practical point of view, in Cuba conditions. This method allowed to determine plutonium activity levels in the marine sediments from Cienfuegos Bay. The selected method of radiochemical separation was that of anionic chromatography and the measure technique was the quadrupole inductively coupled plasma mass spectrometry. The method was applied to a certified reference material, six repetitions were carried out and a good correspondence between the average measured value and the average certified value of plutonium was achieved, so the trueness of the method was demonstrated. It was also proven the precision of the method, since it was obtained a variation coefficient of 11% at 95% confidence level. The obtained results show that the presence of plutonium in the analyzed marine sediment samples is only due to the global radioactive fallout. (author)

  4. A global survey of the distribution of free gas in marine sediments

    Science.gov (United States)

    Fleischer, Peter; Orsi, Tim; Richardson, Michael

    2003-10-01

    Following the work of Aubrey Anderson in the Gulf of Mexico, we have attempted to quantify the global distribution of free gas in shallow marine sediments, and have identified and indexed over one hundred documented cases in the scientific and engineering literature. Our survey confirms previous assumptions, primarily that gas bubbles are ubiquitous in the organic-rich muds of coastal waters and shallow adjacent seas. Acoustic turbidity as recorded during seismo-acoustic surveys is the most frequently cited evidence used to infer the presence of seafloor gas. Biogenic methane predominates within these shallow subbottom deposits. The survey also reveals significant imbalances in the geographic distribution of studies, which might be addressed in the future by accessing proprietary data or local studies with limited distribution. Because of their global prevalence, growing interest in gassy marine sediments is understandable as their presence has profound scientific, engineering and environmental implications.

  5. {sup 137}Cs in marine sediments of Admiralty Bay, King George Island, Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Paulo Alves de Lima [Instituto Oceanográfico, Universidade de São Paulo (IO-USP), Pça. do Oceanográfico, 191, Butantã, SP, 05508 900 (Brazil); Ribeiro, Andreza Portella, E-mail: andrezpr@usp.br [Instituto Oceanográfico, Universidade de São Paulo (IO-USP), Pça. do Oceanográfico, 191, Butantã, SP, 05508 900 (Brazil); Mestrado de Gestão Ambiental e Sustentabilidade, Universidade Nove de Julho (UNINOVE), Avenida Francisco Matarazzo, 612, prédio C, andar térreo, Água Branca, São Paulo, SP, 05001 100 (Brazil); Nascimento, Mylene Giseli do; Martins, Cesar de Castro [Centro de Estudos do Mar, Universidade Federal do Paraná (CEM-UFPR), Av. Beira-mar, no number, Balneário Pontal do Sul, Pontal do Paraná, PR, 83255 971 (Brazil); Mahiques, Michel Michaelovitch de; Montone, Rosalinda Carmelo; Figueira, Rubens Cesar Lopes [Instituto Oceanográfico, Universidade de São Paulo (IO-USP), Pça. do Oceanográfico, 191, Butantã, SP, 05508 900 (Brazil)

    2013-01-15

    The radionuclide cesium-137 ({sup 137}Cs) is produced exclusively by anthropogenic processes and primarily by nuclear explosions. This study determined the reference inventory that is {sup 137}Cs associated with the element's original input, and utilized the levels of activity of this radionuclide previously measured in five sediment profiles collected from Admiralty Bay, Antarctica, to investigate the mobility of this element in the environment. {sup 137}Cs has a half-life of 30 years. Because of this, it is environmentally persistent and has been shown to accumulate in marine organisms. The mean reference inventory of this radionuclide in Admiralty Bay sediments, determined using high resolution gamma ray spectrometry, was 20.23 ± 8.94 Bq m{sup −2}, and within the ambient {sup 137}Cs activity range. A model of {sup 137}Cs diffusion–convection was applied to data collected from 1 cm intervals in sediment cores with the aim of providing insights with respect to this element's behavior in sediments. Model results showed a significant correlation between measured and modeled values using the concentrations of {sup 137}Cs, and estimated input into the system from the global fallout of past nuclear tests and expected values based on local sedimentation rates. Results highlight the importance of accounting for the vertical diffusion of {sup 137}Cs in marine sediments when used as a tracer for environmental processes and for assessing potential bioavailability. - Highlights: ► Cesium-137 ({sup 137}Cs) is produced exclusively by anthropogenic processes. ► A model of diffusion–convection simulated {sup 137}Cs environmental behavior. ► This is important for assessing the bioavailability of this toxic element. ► In Antarctica ice cover influenced the input to the sediments.

  6. 137Cs in marine sediments of Admiralty Bay, King George Island, Antarctica

    International Nuclear Information System (INIS)

    The radionuclide cesium-137 (137Cs) is produced exclusively by anthropogenic processes and primarily by nuclear explosions. This study determined the reference inventory that is 137Cs associated with the element's original input, and utilized the levels of activity of this radionuclide previously measured in five sediment profiles collected from Admiralty Bay, Antarctica, to investigate the mobility of this element in the environment. 137Cs has a half-life of 30 years. Because of this, it is environmentally persistent and has been shown to accumulate in marine organisms. The mean reference inventory of this radionuclide in Admiralty Bay sediments, determined using high resolution gamma ray spectrometry, was 20.23 ± 8.94 Bq m−2, and within the ambient 137Cs activity range. A model of 137Cs diffusion–convection was applied to data collected from 1 cm intervals in sediment cores with the aim of providing insights with respect to this element's behavior in sediments. Model results showed a significant correlation between measured and modeled values using the concentrations of 137Cs, and estimated input into the system from the global fallout of past nuclear tests and expected values based on local sedimentation rates. Results highlight the importance of accounting for the vertical diffusion of 137Cs in marine sediments when used as a tracer for environmental processes and for assessing potential bioavailability. - Highlights: ► Cesium-137 (137Cs) is produced exclusively by anthropogenic processes. ► A model of diffusion–convection simulated 137Cs environmental behavior. ► This is important for assessing the bioavailability of this toxic element. ► In Antarctica ice cover influenced the input to the sediments

  7. Derivation of the nonlinearity parameter B/A of saturated, unconsolidated marine sediments via a statistical approach

    Science.gov (United States)

    Lee, H.; Noh, E.; Ohm, W.-S.; Kwon, O.-C.

    2015-10-01

    Marine sediments are known to exhibit the nonlinearity parameter B/A that is much greater than that of homogeneous fluids and solids. The enormous value of B/A is particularly sensitive to the state of grain contacts. Although there exists a large body of literature that deals with the B/A of marine sediments, few studies have addressed how the random nature of grain contacts affects B/A. Here, we develop a model for the B/A of saturated, unconsolidated marine sediments, which accounts for random grain contacts. The number of contacts per grain and the distribution of contact stress between grains are treated statistically. The quadratic nonlinearity of the equivalent suspension of grains and the interstitial fluid is then combined with the nonlinearity arising from the random Hertzian contacts to produce the effective B/A of marine sediments.

  8. Heavy metal burden in coastal marine sediments of north west coast of India in relation to pollution

    Digital Repository Service at National Institute of Oceanography (India)

    Rokade, M.A.

    IN COASTAL MARINE SEDIMENTS OF NORTH WEST COAST OF INDIA IN RELATION TO POLLUTION A THESIS SUBMITTED TO THE UNIVERSITY OF MUMBAI FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN INORGANIC CHEMISTRY SUBMITTED BY M. A. ROKADE UNDER...

  9. Microbial mercury transformations in marine, estuarine and freshwater sediment downstream of the Idrija Mercury Mine, Slovenia

    International Nuclear Information System (INIS)

    The Idrija Mine, the second largest Hg mine in the world, ceased operation in 1995, but still delivers large quantities of Hg downstream including into the northern Adriatic Sea, 100 km away. Transformation of Hg species in sediment in sites over 60 km from the mine, including marine sites in the Adriatic Sea, was measured to determine the ability of the system to transform and mobilize Hg and to produce methylmercury (MeHg). Cores from a freshwater impoundment, a brackish estuarine site, and three marine sites in the Gulf of Trieste were sectioned anaerobically, and Hg methylation and MeHg demethylation activities determined using radio-techniques (203Hg for methylation and 14C-MeHg for demethylation). Total and dissolved Hg and MeHg were determined as were other geochemical parameters. In addition, rates of SO4 reduction were determined in marine sediment using a 35S technique. Mercury was readily methylated and demethylated at all sites. Marine sediment was investigated in winter and summer with rates of Hg transformation and SO4 reduction corresponding only in winter. Methylation of Hg in summer displayed subsurface peaks that may have been influenced by bioturbation. Total Hg and MeHg were most abundant in the freshwater, estuarine, and near-shore marine sites, but dissolved pore water Hg and MeHg were highest in the estuarine region where S cycling appeared ideal for the mobilization of Hg. The impoundment sediment also seemed to be a 'hotspot' of Hg transformations. MeHg demethylation occurred via the oxidative demethylation pathway (CO2 produced from MeHg), except in surficial sediment offshore in the Gulf during winter, where sediment was more oxidizing and significant amounts of CH4 were liberated during MeHg degradation via reductive demethylation. The CH4 formation was likely due to an increased influence from the expression of MeHg degradative enzymes encoded by the mer detoxification bacterial genetic system. The freshwater site also liberated CH4

  10. Quantitative research for pollution levels in marine sediments of Ha Long Bay by nuclear technique

    International Nuclear Information System (INIS)

    Under the theme of Quantitative study of pollution levels in marine sediments of Halong bay by nuclear techniques conducted from June 2011 to June 2013, the authors conducted monitoring, sediment samples collected in the bay below the sediment column at 8 locations, in which 7 columns located at the estuary near Tuan Chau Island and 1 column at the area near the harbor of Cam Pha. The column samples were taken to the laboratory, cut slices with a distance of 2 cm in the form of frozen and conduct tests of radioactive Pb-210 to determine the rate of sediment in the survey area. Evaluation results based on the method by determining 210Pb, the sediment rate showed speed in the survey area ranged from 0.3 cm.a-1 to 1.2 cm.a-1 and an average of 1.0 cm.a-1. The slices of sediment samples (110 samples) were analyzed heavy metals (KLN) and As elemental by ICP-MS method. These sediment sample also were analyzed for simultaneous determination of N and P and total organic carbon (TOC). Results showed that heavy metal concentrations and As is smaller than the value specified in the National Technical Regulation on Sediment Quality of Vietnam (QCVN), phosphorus concentration less than that can cause harmful effects, but the concentration of total nitrogen and organic carbon that may exceed be harmful as directed by Canadian standards (Persuad et al. 1992). The concentration data in the Halong bay sediment were processed by statistical software SPSS-18, results showed high correlation between the quality TOC, N, P, K and correlation the majority of KLN, this proves the origin of sediments is part of the natural soil components and parts (TOC, N, P, K) is due to the activity of human activity as well as by agricultural fertilizers. The average content of elements in sediments Halong be compared with other data published works of sediment Quang Ninh area, the results show the correlation figures are also high. However, the results of the analysis of KLN and As in Halong sediment

  11. Seismic peak amplitude as a predictor of TOC content in shallow marine sediments

    Science.gov (United States)

    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.

  12. Modelling the cohesive sediment transport in the marine environment: the case of Thermaikos Gulf

    OpenAIRE

    Y. N. Krestenitis; Kombiadou, K. D.; Savvidis, Y. G.

    2007-01-01

    The transport of fine-grained sediments in the marine environment entails risks of pollutant intrusions from substances absorbed onto the cohesive flocks' surface, gradually released to the aquatic field. These substances include nutrients such as nitrate, phosphate and silicate compounds from drainage from fertilization of adjacent cultivated areas that enter the coastal areas through rivers and streams, or trace metals as remainders from urban and industrial activities. As a consequenc...

  13. Evaluating spatial patterns of dioxins in sediments to aid determination of potential implications for marine reptiles

    Energy Technology Data Exchange (ETDEWEB)

    Hermanussen, S.; Gaus, C. [National Research Centre for Environmental Toxicology, Brisbane (Australia); Limpus, C.J. [Queensland Environmental Protection Agency, Brisbane (Australia); Paepke, O. [ERGO Forschungsgesellschaft mbH, Hamburg (Germany); Blanshard, W. [Sea World, Gold Coast (Australia); Connell, D. [School of Public Health, Griffith Univ., Brisbane (Australia)

    2004-09-15

    Recent investigations have identified elevated concentrations of polychlorinated dibenzo-p-dioxins (dioxins) in marine sediments and wildlife of Queensland, Australia. While it has been demonstrated that the contamination is widespread and predominantly land-based, limited information exists on the pathways and fate of these compounds within the near-shore marine system. This environment supports unique and threatened species including green sea turtles (Chelonia mydas). Adult green turtles are predominantly herbivorous, feeding on seagrass and algae. Apart from initial migration to feeding grounds (at {proportional_to}10 years of age) and intermittent migrations to breeding grounds (at {proportional_to}30-50 years and thereafter), green turtles remain and feed within relatively small home ranges. Long life-span (50 years or more), near-shore feeding grounds and highly specialized food requirements render green turtles potentially vulnerable to contaminant exposure. Recent studies have shown a relationship between PCDD/F concentrations found in herbivorous marine wildlife and concentrations in sediments of their habitats. Hence, the spatial evaluation of sediment PCDD/F distribution may assist the assessment of green turtle exposure and its potential implications. The present study provides baseline information on green turtle PCDD/F concentrations in Queensland, Australia and investigates exposure pathways. In addition, spatial distribution of PCDD/Fs in sediments from known green turtle feeding regions is assessed using geographic information systems. This represents the first stage of a large scale investigation into the exposure and sensitivity of marine reptiles to dioxins and dioxin-like compounds and to evaluate whether poor health status observed in some populations may be related to contaminant exposure.

  14. Metal release from contaminated estuarine sediment under pH changes in the marine environment

    OpenAIRE

    Martin-Torre, C; PAYAN, C; Verbinnen, B; Coz, A.; Ruiz, G.; Vandecasteele, C; Viguri, R

    2015-01-01

    The contaminant release from estuarine sediment due to pH changes was investigated using a modified CEN/TS 14429 pH-dependence leaching test. The test is performed in the range of pH values of 0–14 using deionised water and seawater as leaching solutions. The experimental conditions mimic different circumstances of the marine environment due to the global acidification, carbon dioxide (CO2) leakages from carbon capture and sequestration technologies, and accidental chemical spills in seawater...

  15. 87Sr/86Sr measurements on marine sediments by inductively coupled plasma-mass spectrometry

    International Nuclear Information System (INIS)

    The application of inductively coupled plasma-mass spectrometry (ICP-MS) is documented for the study of the strontium isotopic composition (87Sr/86Sr) in geological samples, i.e. in the marine lithic fraction of core sediments. Methods for the determination of the isotopic composition, its accuracy and precision are reported. The results obtained simultaneously on 11 samples by both ICP-MS and thermal ionization mass spectrometry (TIMS) reveal a very good correlation (r2 = 0.955). (orig.)

  16. Reductive dechlorination of tetrachloroethene in marine sediments: Biodiversity and dehalorespiring capabilities of the indigenous microbes.

    Science.gov (United States)

    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

  17. A novel approach to the assess biotic oxygen consumption in marine sediment communities

    Science.gov (United States)

    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

  18. Linking microbial community structure to biogeochemical function in coastal marine sediments: Stable isotope probing combined with magnetic bead capture

    OpenAIRE

    Stal, L.J.; Boschker, H.T.S.; Miyatake, T.

    2011-01-01

    Microbial community structure and its biogeochemical functions in marine sediments can be successfully linked by using the improved Mag-SIP method in combination with other approaches. In this thesis, we were able to provide detailed information on the microorganisms responsible for the utilization of major substrates in marine sediments. It was shown that a number of important groups in the microbial community played a broader role than expected. Some surprising results are that oxygenic pho...

  19. Plio-Pleistocene imprint of natural climate cycles in marine sediments

    International Nuclear Information System (INIS)

    The response of Earth to natural climate cyclicity is written in marine sediments. The Earth is a complex system, as is climate change determined by various modes, frequency of cycles, forcings, boundary conditions, thresholds, and tipping elements. Oceans act as climate change buffers, and marine sediments provide archives of climate conditions in the Earths history. To read climate records they must be well-dated, well-calibrated and analysed at high-resolution. Reconstructions of past climates are based on climate variables such as atmospheric composition, temperature, salinity, ocean productivity and wind, the nature and quality which are of the utmost importance. Once the palaeoclimate and palaeoceanographic proxy-variables of past events are well documented, the best results of modelling and validation, and future predictions can be obtained from climate models. Neither the mechanisms for abrupt climate changes at orbital, millennial and multi-decadal time scales nor the origin, rhythms and stability of cyclicity are as yet fully understood. Possible sources of cyclicity are either natural in the form of internal ocean-atmosphere-land interactions or external radioactive forcing such as solar irradiance and volcanic activity, or else anthropogenic. Coupling with stochastic resonance is also very probable. I provide here, an overview of the cyclicity affecting the Earth on various time scales focussing upon the Plio-Pleistocene and Holocene epochs, together with a compilation of some of the key questions under debate, and a number of representative works that illustrate cyclicity in marine sediments. (Author)

  20. Plutonium isotopes in marine sediments and some biota from the Sudanese coast of the Red Sea

    International Nuclear Information System (INIS)

    Measurements of 239+240Pu and 238Pu were carried out on marine biota as well as on sediments from the fringing reefs area extending towards north and south (Flamingo Bay) of Port Sudan harbour. The analyses were performed using radiochemical separation and alpha spectrometry. The range of the activity concentrations in marine sediments, in mBq kg-1 dry weight, was found to be from 5.10 to 82.00 for 239+240Pu and from 0.89 to 8.63 for 238Pu. Corresponding activity concentrations of 239+240Pu and 238Pu in sediments from the harbours at Port Sudan and Sawakin were 53-301 and 8.29-28.6 (Port Sudan) and 163-343 and 4.7 (Sawakin), respectively. The higher values for plutonium in marine algae suggest their suitability as an indicator species for monitoring purposes. The results obtained are generally lower than those found by other studies and show that the Red Sea environment is mildly affected by plutonium contamination. Activity ratios of plutonium isotopes confirm that the existence of plutonium in the Red Sea is mainly due to atmospheric global fallout. (authors)

  1. Marine coastal sediments microbial hydrocarbon degradation processes: contribution of experimental ecology in the omics’era

    Directory of Open Access Journals (Sweden)

    Cristiana eCravo-Laureau

    2014-02-01

    Full Text Available 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

  2. Bacillus cellulasensis sp. nov., isolated from marine sediment.

    Science.gov (United States)

    Mawlankar, Rahul; Thorat, Meghana N; Krishnamurthi, Srinivasan; Dastager, Syed G

    2016-01-01

    A novel bacterial strain NIO-1130(T) was isolated from sediment sample taken from Chorao Island, Goa Province, India, and subjected to a taxonomic investigation. The strain was Gram-positive, aerobic, and motile. Phylogenetic analysis based on 16S rRNA gene sequences placed the isolate within the genus Bacillus and strain NIO-1130(T) showed highest sequence similarity with Bacillus halosaccharovorans DSM 25387(T) (98.4%) and Bacillus niabensis CIP 109816(T) (98.1%), whereas other Bacillus species showed <97.0% similarity. Tree based on gyrB gene sequence revealed that strain bacillus group. The major menaquinone was MK-7 and the predominant cellular fatty acids were iso-C15:0, anteiso-C15:0, iso-C17:0, and anteiso-C17:0. The strain showed a DNA G+C content of 39.9 mol%. DNA-DNA hybridization studies revealed that strain NIO-1130(T) exhibits 70% similarity with Bacillus halosaccharovorans DSM 25387(T) and Bacillus niabensis CIP 109816(T). On the basis of physiological, biochemical, chemotaxonomic and phylogenetic analyses, we consider the isolate to represent a novel species of the genus Bacillus, for which the name Bacillus cellulasensis sp. nov., is proposed. The type strain is NIO-1130(T) (=NCIM 5461(T)=CCTCC AB 2011126(T)). PMID:26410293

  3. The geochemistry of uranium and thorium in coastal marine sediments and sediment pore waters

    International Nuclear Information System (INIS)

    Pore water profiles of uranium and thorium isotopes in the muddy sediments of Buzzards Bay, MA permit an assessment of the effect of diagenetic redox reactions on the geochemical behaviour of these elements. Uranium shows a pronounced minimum pore water concentration (approx. 1.2dpm/kg) near the sediment water interface (0-3 cm) which coincides with the pore water Fe maximum. U concentrations increase with depth to a broad maximum which is greater than the overlying seawater value, then decrease. The coincidence of the pore water uranium and Fe maximum is consistent with the hypothesis of reduction of U(VI) to U(IV) and removal from solution at about the same depth (or pe) as Fe is reduced. Increases in pore water U with depth appear to be related to release of authigenic (seawater) U(VI) to solution, possibly as alkalinity and pH increase and organic matter with which the U is associated is oxidized. In contrast, pore water profiles of the long-lived Th isotopes 232Th and 230Th show low activities (234Th shows greatest pore water activities in the upper 5 cm and is present at virtually zero activities elsewhere in the sediment column. The upper few centimeters of the sediment generally contain excess 234Th scavenged from the overlying water column and distributed by bioturbation. (author)

  4. Effects of four aromatic organic pollutants on microbial glucose metabolism and thymidine incorporation in marine sediments

    International Nuclear Information System (INIS)

    The metabolism of D-(U-14C)glucose and the incorporation of (methyl-3H)thymidine by aerobic and anaerobic marine sediment microbes exposed to 1 to 1000 ppm anthracene, naphthalene, p,p'-dichlorodiphenyltrichloroethane, and pentachlorophenol were examined. Cell-specific rates of (14C)glucose metabolism averaged 1.7 x 10-21 and 0.5 x 10-21 mol/min per cell for aerobic and anaerobic sediment slurries, respectively; (3H)thymidine incorporation rates averaged 43 x 10-24 and 9 x 10-24 mol/min per cell for aerobic and anaerobic slurries, respectively. Aerobic sediments exposed to three of the organic pollutants for 2 to 7 days showed recovery of both activities. Anaerobic sediments showed little recovery after 2 days of pre-exposure to the pollutants. The authors conclude that (i) anaerobic sediments are more sensitive than aerobic sediments to pollutant additions; (ii) (3H)thymidine incorporation is more sensitive to pollutant additions than is (14C)glucose metabolism; and (iii) the toxicity of the pollutants increased in the following order: anthracene, p,p'-dichlorodiphenyltrichloroethane, naphthalene, and pentachlorophenol

  5. Influences of marine sediment on the accumulation of radionuclides by green alga (Ulva pertusa)

    International Nuclear Information System (INIS)

    Distribution of radionuclides (60Co, 137Cs, 95Zr-95Nb and 106Ru-106Rh) among green alga (Ulva pertusa), sea water and marine sediment were examined by radioisotope tracer experiment in order to estimate the influence of sediment on the accumulation of radionuclides by the alga. By the application of the compartment model to the experimental results, exponential formulas of distributions were obtained. Through comparison of the transfer coefficients of radionuclides calculated from the exponential formulas, the influence of the sediment on the accumulation of the radionuclides by the green alga was determined to be the largest for 60Co, followed by 95Zr-95Nb, 106Ru-106Rh and 137Cs in this order. The activity ratios of 95Zr-95Nb and 106Ru-106Rh calculated from the transfer coefficients are larger for the alga than for the sediment, inversely those of 60Co and 137Cs show higher values for the sediment than for the alga. Especially, in the case of 60Co, the activity ratio for the sediment is approximately 20 times greater than that for the alga. Biological half lives in green alga estimated from the transfer coefficients were 10 days for 60Co, 7 days for 137Cs, 26 days for 95Zr-95Nb and 24 days for 106Ru-106Rh. (auth.)

  6. Experimental results on bioaccumulation of metals and organic contaminants from marine sediments.

    Science.gov (United States)

    Ruus, Anders; Schaanning, Morten; Oxnevad, Sigurd; Hylland, Ketil

    2005-04-30

    A test-system for the assessment of bioavailability and bioaccumulation of metals and organic contaminants in marine benthic organisms is described and results from studies where this system has been applied are assessed. Sediments tested were polluted harbour sediment (from Norway), and clean sediments spikes with metal containing weight materials for drilling muds. Contaminants that may bioaccumulate under relevant conditions are indicated. The test-system uses two species of ecological relevance (Nereis diversicolor and Hinia reticulata). Interspecies differences in bioaccumulation were found for several compounds, which show the importance of using species with different modes of living in such tests. Compared to other PAHs, pyrene was found to bioaccumulate to a high degree (BioAccumulation Ratio, BAR=213.5>sediment concentration ratio, SCR=97.4; bioaccumulation factor, organism dw. conc. to sediment dw. conc., BAF=1.02), which shows that extrapolating bioaccumulation results between different substances is difficult. When assessing bioavailability of specific compounds, it is most adequate to perform direct measurements on exposed organisms, such as the experiments described here. The high bioaccumulation of compounds such as pyrene and nickel may in some cases be attributed to manipulation of the sediments and (for pyrene) lack of subsequent aging, thereby overestimating bioavailability. PMID:15820107

  7. Certification of Trace Element Mass Fractions in IAEA-457 Marine Sediment Sample

    International Nuclear Information System (INIS)

    The primary goal of the IAEA Environment Laboratories in Monaco (NAEL) is to help Member States understand, monitor and protect the marine environment. The major impact exerted by large coastal cities on marine ecosystems is therefore of great concern to the IAEA and its Environment Laboratories. Given that marine pollution assessments of such impacts depend on accurate knowledge of contaminant concentrations in various environmental compartments, the NAEL has assisted national laboratories and regional laboratory networks through its Reference Products for Environment and Trade programme since the early 1970s. Quality assurance (QA), quality control (QC) and associated good laboratory practice are essential components of all marine environmental monitoring studies. QC procedures are commonly based on the analysis of certified reference materials and reference samples in order to validate analytical methods used in monitoring studies and to assess reliability and comparability of measurement data. QA can be realized by participation in externally organized laboratory performance studies, also known as interlaboratory comparisons, which compare and evaluate analytical performance and measurement capabilities of participating laboratories. Data that are not based on adequate QA/QC can be erroneous and their misuse can lead to incorrect environmental management decisions. A marine sediment sample with certified mass fractions for Ag, Al, As, Cd, Cr, Co, Cu, Fe, Hg, Li, Mn, Ni, Pb, Sn, Sr, V and Zn was recently produced by the NAEL in the frame of a project between the IAEA and the Korea Institute of Ocean Science and Technology. This report describes the sample preparation methodology, the material homogeneity and stability study, the selection of laboratories, the evaluation of results from the certification campaign and the assignment of property values and their associated uncertainty. As a result, reference values for mass fractions and associated expanded

  8. Certification of Trace Elements and Methyl Mercury Mass Fractions in IAEA-456 Marine Sediment Samples

    International Nuclear Information System (INIS)

    The primary goal of the IAEA Environment Laboratories is to assist Member States in the use of both stable and radioisotope analytical techniques to understand, monitor and protect the environment. In this context, the major impact of large coastal cities on marine ecosystems is an issue of prime concern for the IAEA and the IAEA Environment Laboratories. The marine pollution assessments required to understand such impacts depend on accurate knowledge of contaminant concentrations in various environmental compartments. The IAEA Environment Laboratories has been assisting national laboratories and regional laboratory networks since the early 1970s through the provision of a reference material programme for the analysis of radionuclides, trace elements and organic compounds in marine samples. Quality assurance, quality control and associated good laboratory practice are essential components of all marine environmental monitoring studies. Quality control procedures are commonly based on the analysis of certified reference materials and reference samples in order to validate analytical methods used in monitoring studies and to assess t h e reliability and comparability of measurement data. Data that are not based on adequate quality assurance and quality control can be erroneous, and their misuse can lead to poor environmental management decisions. A marine sediment sample with certified mass amount contents for aluminium, arsenic, cadmium chromium, cobalt, copper, iron, lead, mercury, methyl mercury, manganese, nickel, vanadium and zinc was recently produced by the IAEA Environment Laboratories. This publication presents the sample preparation methodology, including material homogeneity and the stability study, the selection of laboratories, the evaluation of results from the certification campaign, and the assignment of property values and their associated uncertainty. As a result, certified values for mass fractions and associated expanded uncertainty were

  9. Kinetic parameters for nutrient enhanced crude oil biodegradation in intertidal marine sediments

    Directory of Open Access Journals (Sweden)

    Arvind K Singh

    2014-04-01

    Full Text Available Availability of inorganic nutrients, particularly N and P, is often a primary control on crude oil hydrocarbon degradation in marine systems. 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&P are not limiting. Crude oil degradation was limited by both N&P availability. When N was added alone maximum rates of CO2 production measured were 3.94±0.46 µmol CO2 /g wet sediment/day. However when the same levels of N 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 more than doubled (11.52±0.72 µmol CO2 /g wet sediment/day. Ks and qmax estimates for N (in the form of sodium nitrate when P was not limiting were 1.57±0.56 µmol/g wet sediment and 10.57±0.63 µmol CO2 /g wet sediment/day respectively. The corresponding values for P were 80 nmol/g wet sediment and 8.76±1.15 µmol CO2 /g wet sediment/day. The qmax values with respect to N and P were not significantly different (P< 0.05. Analysis of bacterial 16S rRNA genes indicated that Alcanivorax spp. were selected in these marine sediments with increasing inorganic nutrient concentration, whereas Cycloclasticus spp. were more prevalent at lower inorganic nutrient concentrations. These data suggest that simple empirical estimates of the proportion of nutrients added relative to crude oil concentrations may not be sufficient to guarantee successful crude oil bioremediation in oxic beach sediments. The data we present also help define the maximum rates and hence timescales required for bioremediation

  10. Assessment and management of contaminated sediments in Italian marine coastal waters

    International Nuclear Information System (INIS)

    The Water Framework Directive (WFD) obliges Member State to achieve a good chemical and ecological status of all surface water bodies within a specific deadline; in particular the good chemical status is a condition in which the concentrations of priority substances do not exceed the environmental quality standards (EQS) in order to protect human health and the environment; the WFD states that EQS have to be derived for water, sediment or biota. The good chemical status could be difficult to achieve in the historical marine contaminated water bodies due to the presence of high concentrations of toxic, bio accumulative and persistent substances in the sediments. In these specific highly contaminated sites there is a need to apply an ecosystem approach in which, as a first step, less stringent sediment EQS are defined in order to take the appropriate measures for the protection of aquatic ecosystems and human health; the long-term goal for these sites is the achievement of the good chemical status foreseen by the WFD. The methodology applied in Italy for the sediment quality assessment of marine contaminated sites is explained in this paper

  11. A 35,000 year record of terrigenous and marine lipids in Amazon Fan sediments

    Energy Technology Data Exchange (ETDEWEB)

    Boot, C.S.; Pancost, R.D. [Bristol Univ. (United Kingdom). Organic Geochemistry Unit; Ettwein, V.J.; Maslin, M.A. [University College London (United Kingdom). Environmental Change Research Centre; Weyhenmeyer, C.E. [Lawrence Livermore National Lab., CA (United States)

    2006-02-15

    Elemental and lipid analyses were carried out on sediments recovered from Ocean Drilling Program (ODP) Site 942 to provide a 35 kyr record of organic matter input to Amazon Fan sediments. Total organic carbon (TOC) and higher plant biomarker mass accumulation rates were an order of magnitude greater during the last glacial period compared to the current interglacial due to sea-level controlled variations in Amazon River sediment supply. Large maxima were also seen at {approx} 12 ka, which are most likely due to discharge events. Higher plant n-alkane average chain lengths did not change throughout the record, suggesting consistency in the source vegetation type. The abundance of taraxerol relative to other plant biomarkers increased at {approx} 12 ka, indicating increased mangrove input due to either higher mangrove productivity or increased erosion of mangrove deposits. The mass accumulation rates (MARs) of some bacterial and eustigmatophyte biomarkers varied closely with those of higher plant biomarkers and so seem to have a non-marine source. Long chain alkenones were present in some of the sediments, generally in very low concentration, indicating dilution of the marine signal with terrestrial organic matter. (author)

  12. Micromonospora fluostatini sp. nov., isolated from marine sediment.

    Science.gov (United States)

    Phongsopitanun, Wongsakorn; Kudo, Takuji; Mori, Mihoko; Shiomi, Kazuro; Pittayakhajonwut, Pattama; Suwanborirux, Khanit; Tanasupawat, Somboon

    2015-12-01

    The novel actinomycete strain PWB-003T, which produced fluostatins B and C antibiotics, was isolated from nearshore sediment collected from Panwa Cape, Phuket Province, Thailand. Data from the present polyphasic study indicated that strain PWB-003T represented a member of the genus Micromonospora. It produced single spores on substrate mycelia and contained meso-diaminopimelic acid in the cell-wall peptidoglycan. Whole-cell hydrolysate contained ribose, xylose, arabinose, mannose and glucose. The predominant menaquinone was MK-10 (H4). Cellular fatty acids comprised C18 : 1ω9c, iso-C16 : 0, anteiso-C17 : 0, iso-C15 : 0 and iso-C17 : 0. On the basis of 16S rRNA gene sequence similarity analysis, the novel strain was closely related to Micromonospora eburnea LK2-10T (99.38 %), Micromonospora chaiyaphumensis MC5-1T (99.16 %), Micromonospora yangpuensis FXJ6.011T (98.97 %), Micromonospora echinaurantiaca DSM 43904T (98.97 %), Micromonospora pallida DSM 43817T (98.97 %), Micromonospora sagamiensis DSM 43912T and Micromonospora auratinigra JCM 12357T (both 98.97 %). The G+C content of the DNA was 74.5 mol%. DNA-DNA relatedness values among strain PWB-003T and related type strains ranged from 11.3 ± 1.3 to 38.8 ± 1.1 %. On the basis of these observations, strain PWB-003T could be distinguished from its closely related type strains and is considered to represent a novel species of the genus Micromonospora, for which the name Micromonospora fluostatini sp. nov. (type strain PWB-003T = JCM 30529T = PCU 341T = TISTR 2345T) is proposed. PMID:26358439

  13. Sediment characteristics and benthic ecological status in contrasting marine environments of subtropical Hong Kong.

    Science.gov (United States)

    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. PMID:26749224

  14. Marine meiofauna, carbon and nitrogen mineralization in sandy and soft sediments of Disko Bay, West Greenland

    DEFF Research Database (Denmark)

    Rysgaard, S.; Christensen, P.B.; Sørensen, Martin Vinther; Funch, P.; Berg, P.

    2000-01-01

    Organic carbon mineralization was studied in a shallow-water (4 m), sandy sediment and 2 comparatively deep-water (150 and 300 m), soft sediments in Disko Bay, West Greenland. Benthic microalgae inhabiting the shallow-water locality significantly affected diurnal O-2 conditions within the surface...... and was, together with organotrophic O-2 respiration, the most important pathway for carbon mineralization within these sediments. The obtained process rates were comparable to mineralization rates from much warmer localities, suggesting that benthic mineralization in arctic marine environments is...... belonging to Platyhelminthes, Rotifera, Gastrotricha, and Protodriloidae (Polychaeta) occurred only at the sandy locality, whereas Kinorhyncha, Foraminifera, and Cumacea (Crustacea) occurred only at the muddy stations. The larger number of meiofauna individuals at the sandy locality may in part be explained...

  15. Vertical activity distribution of dissimilatory nitrate reduction in coastal marine sediments

    DEFF Research Database (Denmark)

    Behrendt, A.; de Beer, D.; Stief, P.

    2013-01-01

    The relative importance of two dissimilatory nitrate reduction pathways, denitrification (DEN) and dissimilatory nitrate reduction to ammonium (DNRA), was investigated in intact sediment cores from five different coastal marine field sites (Dorum, Aarhus Bight, Mississippi Delta, Limfjord...... reduction was clearly dominated by DEN (59-131% of the total NO3- reduced) rather than by DNRA, irrespective of the sedimentary inventories of electron donors such as organic carbon, sulfide, and iron. Highest ammonium production via DNRA, accounting for up to 8.9% of the total NO3- reduced, was found...... at a site with very high concentrations of total sulfide and NH4+ within and below the layer in which NO3- reduction occurred. Sediment from two field sites, one with low and one with high DNRA activity in the core incubations, was also used for slurry incubations. Now, in both sediments high DNRA activity...

  16. Extreme seawater compositions during Oceanic Anoxic Events

    Science.gov (United States)

    Cohen, A.; Bottini, C.; Dickson, A. J.; Izon, G. J.; Coe, A. L.

    2012-12-01

    For almost the entire duration of the Phanerozoic, the oceans have remained well oxygenated and highly conducive to the development of animal and plant life. However, there have been relatively brief intervals, known as Oceanic Anoxic Events (OAEs), when a very significant expansion of low-oxygen regions occurred throughout the world's oceans. OAEs were characterised by highly atypical seawater chemistry, as reflected in the chemical and isotopic compositions of contemporaneous sediments and fossil remains. These oxygen-deficient intervals also exerted profound pressures on many marine species as indicated by major changes in species populations and distributions. High-resolution chemical and isotopic data recovered from marine sediments and sedimentary rocks, together with biotic information, provide us with the best means of understanding the significance of OAEs and their place in the evolution of the Earth system. We present new Mo- and Os-isotope and geochemical data from OAE 1a (early Cretaceous), which help define how this event evolved in relation to the other major environmental parameters - including global warming, continental weathering and Ontong-Java volcanism - of that time. We compare these new observations with published results from other Mesozoic OAEs and the PETM. Recently published Os-isotope data from DSDP site 463 (mid-Pacific) [1] and northern Italy [1, 2] show that the Os budget of the oceans was dominated for a period of c. 880 ka during OAE 1a by the hydrothermal flux of unradiogenic Os from the Ontong-Java province. The observation of identical Os-isotope compositions at these two very distant sites indicates that seawater was well mixed at that time. Over the same interval, the seawater Mo-isotope composition, based upon well-preserved samples from Italy, was persistently atypical, with δ98/95Mo ranging between -0.7 and +0.7 permil [3]. All the samples analysed here accumulated under highly anoxic conditions and contain highly abundant

  17. Assessment of radionuclides and heavy metals in marine sediments along the Upper Gulf of Thailand

    Science.gov (United States)

    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.

  18. Neutron activation analysis of stream bed and marine sediments for river and coastal resource management

    International Nuclear Information System (INIS)

    Stream bed sediments from four sites in the tributaries Aklan River, and five marine coastal sediments from Batan, Aklan, were analyzed to evaluate an analytical method for the determination of major (Cl, Ti, Ca, Mg, P, Si, Fe, Al, Na, K, Mn) and trace elements (Cu,Ba, As, Cd, Co, Cr, Mo, Ga, Ni, Mb, Th, Sr, Sn, S, Pb, Rb, Zr, Zn, V, Yb, Sc, Se, Br, La, Ce, Au,) using neutron activation analysis, NAA. Samples were prepared by grinding the sediments to fine powders and subjecting the processed samples to either short irradiation (10 s) and/or long irradiation (20 min) in a nuclear reactor. The JRR-3, a domestically designed and constructed 20 MW reactor in Japan provides a max thermal flux of 2 x 1014 [cm-2 s-1] in the core. The samples were bombarded with neutron flux from the JRR-3 reactor, to instigate formation of radioactive isotopes. After complete activation, the samples were analyzed using a high purity germanium, HPGe, detector and the spectra of the emissions of the radioactive samples were used to determine the concentrations of the elements. The short-lived radionuclides were counted after 1 week cooling time. Quantification of elemental composition and analysis of accuracy was done by comparison to certified reference material standards: JMS-1 for marine sediments and JSD-11 for river sediments. Detection limits for trace elements were in the part per billion (ppb) range and are adequate for geochemical, agricultural, and environmental purposes. Application of this validated technique affords reliable determination on new mineral potentiality in the sediments and indicate ambient conditions of macro-and micro-nutrients' availability for agriculture/fisheries coastal resource development. (author)

  19. Nitrogen isotopes in bulk marine sediment: linking seafloor observations with subseafloor records

    Directory of Open Access Journals (Sweden)

    J.-E. Tesdal

    2013-01-01

    Full Text Available The stable isotopes of nitrogen offer a unique perspective on changes in the nitrogen cycle, past and present. However, the presence of multiple forms of nitrogen in marine sediments can complicate the interpretation of bulk nitrogen isotope measurements. Although the large-scale global patterns of seafloor δ15N have been shown to match process-based expectations, small-scale heterogeneity on the seafloor, or alterations of isotopic signals during translation into the subseafloor record, could obscure the primary signals. Here, a public database of nitrogen isotope measurements is described, including both seafloor and subseafloor sediment samples ranging in age from modern to the Pliocene, and used to assess these uncertainties. In general, good agreement is observed between neighbouring seafloor sites within a 100 km radius, with 85% showing differences of < 1‰. There is also a good correlation between the δ15N of the shallowest (< 5 ka subseafloor sediments and neighbouring seafloor sites within a 100 km radius (R2 = 0.83, which suggests a reliable translation of sediments into the buried sediment record. Meanwhile, gradual δ15N decreases over multiple glacial–interglacial cycles appear to reflect post-depositional alteration in records from the deep sea (below 2000 m. We suggest a simple conceptual model to explain these 100-kyr-timescale changes in well-oxygenated, slowly accumulating sediments, which calls on differential loss rates for pools of organic N with different δ15N. We conclude that bulk sedimentary nitrogen isotope records are reliable monitors of past changes in the marine nitrogen cycle at most locations, and could be further improved with a better understanding of systematic post-depositional alteration. Furthermore, geochemical or environmental criteria should be developed in order to effectively identify problematic locations and to account for

  20. Salinity Effects on the Biogeochemical Cycles of Sulfate, Arsenate, Nitrate, and Methane in Anoxic Sediments of Mono Lake and Searles Lake, California.

    Science.gov (United States)

    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

  1. Viability of microcomputed tomography to study tropical marine worm galleries in humid muddy sediments

    International Nuclear Information System (INIS)

    Bioturbation is an ecological process driven by organisms, which transports nutrients and gases from air/water to sediment through their galleries, by the time they feed, burrow and/or construct galleries. This exchange is vital to the maintenance of micro and macrobenthic organisms, mainly in muddy flat environments. Species with distinct galleries could create levels of bioturbation, affecting the benthic interactions. In this sense, it is fundamental developing a non-destructive method that permits identifying/quantifying the properties of these galleries. The recent advances in micro-computed tomography are allowing the high resolution 3D images generation. However, once muddy sediments are rich in organic matter and interstitial water, these would lead to motion artifacts which could, in turn, decrease the accuracy of galleries identification/quantification. In this context, the aim of this study was to develop a protocol which combines laboratory experiments and microtomography analysis in order to generate accurate 3D images of the small marine worm's galleries within humid muddy sediments. The sediment was collected at both muddy flats of Surui's and Itaipu lagoon's mangroves (RJ-Brazil), sieved (0.5mm mesh) and introduced with one individual of the marine worm Laeonereis acuta (Nereididae, Polychaeta) in each acrylic corer holders (4.4cm of internal diameter). High energy microtomography scanner was used to obtain 3D images and the setup calibration was 130 kV and 61 mA. Each acquisition image time was among 4h and 6h. Several procedures of drying remained water inside the cores were performed aiming obtaining images without movement artifacts due to circulating water, and this issue was one of the main studied parameter. In order to investigate possible chemical effects, 2ml of formalin (35%) with menthol were added to the surface of the cores. The results show that although the drying time was appropriated, the chemicals created bubbles within the

  2. Viability of microcomputed tomography to study tropical marine worm galleries in humid muddy sediments

    Energy Technology Data Exchange (ETDEWEB)

    Pennafirme, Simone F., E-mail: sipennafirme@gmail.com [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Biologia. Dept. de Biologia Marinha; Machado, Alessandra S.; Lima, Inaya; Suzuki, Katia N.; Lopes, Ricardo T., E-mail: machado@lin.ufrj.br, E-mail: inaya@lin.ufrj.br, E-mail: norisuzuki6@yahoo.com.br, E-mail: ricardo@lin.ufj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), RJ (Brazil). Lab. de Instrumentacao Nuclear

    2013-07-01

    Bioturbation is an ecological process driven by organisms, which transports nutrients and gases from air/water to sediment through their galleries, by the time they feed, burrow and/or construct galleries. This exchange is vital to the maintenance of micro and macrobenthic organisms, mainly in muddy flat environments. Species with distinct galleries could create levels of bioturbation, affecting the benthic interactions. In this sense, it is fundamental developing a non-destructive method that permits identifying/quantifying the properties of these galleries. The recent advances in micro-computed tomography are allowing the high resolution 3D images generation. However, once muddy sediments are rich in organic matter and interstitial water, these would lead to motion artifacts which could, in turn, decrease the accuracy of galleries identification/quantification. In this context, the aim of this study was to develop a protocol which combines laboratory experiments and microtomography analysis in order to generate accurate 3D images of the small marine worm's galleries within humid muddy sediments. The sediment was collected at both muddy flats of Surui's and Itaipu lagoon's mangroves (RJ-Brazil), sieved (0.5mm mesh) and introduced with one individual of the marine worm Laeonereis acuta (Nereididae, Polychaeta) in each acrylic corer holders (4.4cm of internal diameter). High energy microtomography scanner was used to obtain 3D images and the setup calibration was 130 kV and 61 mA. Each acquisition image time was among 4h and 6h. Several procedures of drying remained water inside the cores were performed aiming obtaining images without movement artifacts due to circulating water, and this issue was one of the main studied parameter. In order to investigate possible chemical effects, 2ml of formalin (35%) with menthol were added to the surface of the cores. The results show that although the drying time was appropriated, the chemicals created bubbles

  3. Vitamin B1 in marine sediments: pore water concentration gradient drives benthic flux with potential biological implications

    OpenAIRE

    Monteverde, Danielle R.; Gómez-Consarnau, Laura; Cutter, Lynda; Chong, Lauren; Berelson, William; Sañudo-Wilhelmy, Sergio A.

    2015-01-01

    Vitamin B1, or thiamin, can limit primary productivity in marine environments, however the major marine environmental sources of this essential coenzyme remain largely unknown. Vitamin B1 can only be produced by organisms that possess its complete synthesis pathway, while other organisms meet their cellular B1 quota by scavenging the coenzyme from exogenous sources. Due to high bacterial cell density and diversity, marine sediments could represent some of the highest concentrations of putativ...

  4. Evidence for microbial Fe(III) reduction in anoxic, mining-impacted lake sediments (Lake Coeur d'Alene, Idaho)

    Energy Technology Data Exchange (ETDEWEB)

    Cummings, D.E.; March, A.W.; Bostick, B.; Spring, S.; Caccavo, F. Jr.; Fendorf, S.; Rosenzweig, R.F.

    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{sup {minus}1}, suggesting that iron reduction has occurred recently. The maximum concentrations of dissolved Fe(II) in interstitial water (41 mg liter{sup {minus}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 (Fe{sub 3}O{sub 4}), a common product of bacterial Fe(III) hydroxide reduction, was as much as 15.5 g kg{sup {minus}1}. Most-probable-number enrichment cultures revealed that the mean density of Fe(III)-reducing bacteria was 8.3 x 10{sup 5} cells g (dry weight) of sediment{sup {minus}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.

  5. Methane oxidation coupled to oxygenic photosynthesis in anoxic waters.

    Science.gov (United States)

    Milucka, Jana; Kirf, Mathias; Lu, Lu; Krupke, Andreas; Lam, Phyllis; Littmann, Sten; Kuypers, Marcel M M; Schubert, Carsten J

    2015-09-01

    Freshwater lakes represent large methane sources that, in contrast to the Ocean, significantly contribute to non-anthropogenic methane emissions to the atmosphere. Particularly mixed lakes are major methane emitters, while permanently and seasonally stratified lakes with anoxic bottom waters are often characterized by strongly reduced methane emissions. The causes for this reduced methane flux from anoxic lake waters are not fully understood. Here we identified the microorganisms and processes responsible for the near complete consumption of methane in the anoxic waters of a permanently stratified lake, Lago di Cadagno. Interestingly, known anaerobic methanotrophs could not be detected in these waters. Instead, we found abundant gamma-proteobacterial aerobic methane-oxidizing bacteria active in the anoxic waters. In vitro incubations revealed that, among all the tested potential electron acceptors, only the addition of oxygen enhanced the rates of methane oxidation. An equally pronounced stimulation was also observed when the anoxic water samples were incubated in the light. Our combined results from molecular, biogeochemical and single-cell analyses indicate that methane removal at the anoxic chemocline of Lago di Cadagno is due to true aerobic oxidation of methane fuelled by in situ oxygen production by photosynthetic algae. A similar mechanism could be active in seasonally stratified lakes and marine basins such as the Black Sea, where light penetrates to the anoxic chemocline. Given the widespread occurrence of seasonally stratified anoxic lakes, aerobic methane oxidation coupled to oxygenic photosynthesis might have an important but so far neglected role in methane emissions from lakes. PMID:25679533

  6. Inversion of marine multifrequency electromagnetic profiling data: a new approach to resolve surficial sediment stratification

    Science.gov (United States)

    Baasch, B.; Müller, H.; Oberle, F. K. J.; von Dobeneck, T.

    2014-01-01

    Electromagnetic induction (EMI) methods are widely used on land to map electric conductivity and/or magnetic susceptibility distributions of surficial sediments. In contrast, the application of these methods in marine environments is relatively novel. Based on the recently developed electromagnetic benthic profiler MARUM-NERIDIS III we investigate the potential of concentric-loop EMI methods to recover conductivity and susceptibility of layered marine sediments. Sensitivity analyses based on a data and model normalized Jacobian matrix were performed to compare the influence of conductivity and susceptibility to in-phase and quadrature components at different frequencies. Both parameters substantially affect the EM response. However, the influence of susceptibility decreases more with depth and offers lower depth resolution than that of conductivity. A 1-D inversion algorithm to reconstruct vertical conductivity distributions was developed from existing non-linear inversion methods using apparent conductivity and apparent susceptibility recovered from simultaneous half-space inversion as a priori information. This algorithm was tested on synthetic and real marine EM data from a commercial multifrequency concentric loop EMI system (GEM-3). The results indicate that our inversion algorithm yields meaningful results down to approximately 3 m depth under typical shallow marine conditions. The comparison of inversion results recovered with 1-D and 2-D constraints showed that combining lateral with vertical constraints substantially improves the resolution of the inversion outputs. Field data from the NW Iberian shelf was calibrated according to a processing flow specifically designed for underwater conditions and analysed. Inversion outputs are in good agreement with ground-truthing stratigraphic investigations and deliver relevant clues on past and present sediment dynamics.

  7. Microbial processes and organic priority substances in marine coastal sediments (Adriatic Sea, Italy)

    Science.gov (United States)

    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

  8. Release and migration of activation products from corrosion-resistant metal specimens in marine sediments. Technical report

    International Nuclear Information System (INIS)

    An investigation of the release of Ni-63, Co-60, and Fe-55 from Inconel 600 and 347 stainless steel specimens implanted in marine sediment for one year is described. Radiochemical analysis of the sediment from overcores of the metal specimens permit estimation of integrated activities, release rates, and diffusion coefficients of the three radionuclides. The redox chemistry of the sediments is characterized by measurement of several naturally occurring oxidizing agents and is correlated with the behavior of the radionuclides

  9. Quantitative analysis of anaerobic oxidation of methane (AOM) in marine sediments: A modeling perspective

    Science.gov (United States)

    Regnier, P.; Dale, A. W.; Arndt, S.; LaRowe, D. E.; Mogollón, J.; Van Cappellen, P.

    2011-05-01

    Recent developments in the quantitative modeling of methane dynamics and anaerobic oxidation of methane (AOM) in marine sediments are critically reviewed. The first part of the review begins with a comparison of alternative kinetic models for AOM. The roles of bioenergetic limitations, intermediate compounds and biomass growth are highlighted. Next, the key transport mechanisms in multi-phase sedimentary environments affecting AOM and methane fluxes are briefly treated, while attention is also given to additional controls on methane and sulfate turnover, including organic matter mineralization, sulfur cycling and methane phase transitions. In the second part of the review, the structure, forcing functions and parameterization of published models of AOM in sediments are analyzed. The six-orders-of-magnitude range in rate constants reported for the widely used bimolecular rate law for AOM emphasizes the limited transferability of this simple kinetic model and, hence, the need for more comprehensive descriptions of the AOM reaction system. The derivation and implementation of more complete reaction models, however, are limited by the availability of observational data. In this context, we attempt to rank the relative benefits of potential experimental measurements that should help to better constrain AOM models. The last part of the review presents a compilation of reported depth-integrated AOM rates (ΣAOM). These rates reveal the extreme variability of ΣAOM in marine sediments. The model results are further used to derive quantitative relationships between ΣAOM and the magnitude of externally impressed fluid flow, as well as between ΣAOM and the depth of the sulfate-methane transition zone (SMTZ). This review contributes to an improved understanding of the global significance of the AOM process, and helps identify outstanding questions and future directions in the modeling of methane cycling and AOM in marine sediments.

  10. Novel aromatic ring-hydroxylating dioxygenase genes from coastal marine sediments of Patagonia

    Directory of Open Access Journals (Sweden)

    Ferrero Marcela A

    2008-03-01

    Full Text Available Abstract Background Polycyclic aromatic hydrocarbons (PAHs, widespread pollutants in the marine environment, can produce adverse effects in marine organisms and can be transferred to humans through seafood. Our knowledge of PAH-degrading bacterial populations in the marine environment is still very limited, and mainly originates from studies of cultured bacteria. In this work, genes coding catabolic enzymes from PAH-biodegradation pathways were characterized in coastal sediments of Patagonia with different levels of PAH contamination. Results Genes encoding for the catalytic alpha subunit of aromatic ring-hydroxylating dioxygenases (ARHDs were amplified from intertidal sediment samples using two different primer sets. Products were cloned and screened by restriction fragment length polymorphism analysis. Clones representing each restriction pattern were selected in each library for sequencing. A total of 500 clones were screened in 9 gene libraries, and 193 clones were sequenced. Libraries contained one to five different ARHD gene types, and this number was correlated with the number of PAHs found in the samples above the quantification limit (r = 0.834, p nahAc-like genes, phnAc-like genes as identified in Alcaligenes faecalis AFK2, and phnA1-like genes from marine PAH-degraders from the genus Cycloclasticus. Conclusion These results show the presence of hitherto unidentified ARHD genes in this sub-Antarctic marine environment exposed to anthropogenic contamination. This information can be used to study the geographical distribution and ecological significance of bacterial populations carrying these genes, and to design molecular assays to monitor the progress and effectiveness of remediation technologies.

  11. Determination of multi-element in marine sediment samples collected in Angola by the k0-NAA technique

    International Nuclear Information System (INIS)

    The marine sediment samples were designed to collect in Angola for marine environmental pollution study. The k0-standardization method of neutron activation analysis (k0-NAA) on Dalat research reactor has been developed to determine of multi-element in the Angola marine sediment samples. The samples were irradiated in cell 7-1 for short- and middle-lived nuclides and rotary specimen rack for long-lived nuclides. The irradiation facilities were characterized for neutron spectrum parameters and post-activated samples were measured on the calibrated gamma-ray spectrometers using HPGe detectors. The analytical results for 9 marine sediment samples with 27 elements: Al, As, Br, Ca, Ce,Cl, Co, Cs, Dy, Fe, Hf, I, K, Mg, Mn, Na, Rb, Sb, Sc, Se, Sm, Th, Ti, U, V and Zn in term of mean concentration, standard deviation and their content range are shown in the report. The analytical quality assurance was done by analysis of a Japan's certified reference material namely marine sediment NMIJ-CRM-7302a. These preliminary results revealed that the k0-NAA technique on the Dalat research reactor is a good analytical technique for determination of multi-element in the marine sediment samples. Some heavy metals and trace elements determined in this work possibly connected to the human activities at the sampling region. (author)

  12. Triassic deep-marine sedimentation in the western Qinling and Songpan terrane

    Institute of Scientific and Technical Information of China (English)

    MENG; QingRen; QU; HongJie; HU; JianMin

    2007-01-01

    Triassic sequences in both the western Qinling and Songpan terrane are composed mostly of deep-marine sediments. A detailed study was carried out on main sedimentary facies of Triassic successions, showing that they resulted from diverse sedimentary processes, such as submarine debris-flows, turbidity currents, bottom-flows, suspension fallout, and fluidized sediment flows. Debris-flows are dividable into two types, gravelly and sandy debris-flows, respectively, and the sandy debris-flow deposits make up considerable portion of the Triassic successions concerned. Turbidite is characterized by occurrence of normal grading, and the whole Bouma sequences, though widely developed, are not totally attributed to true turbidity currents. The non-graded Ta division is thought to originate from sandy debris flows, whereas the rest divisions result from low-density currents or from bottom-current modification if they contain sedimentary structures related to traction currents. Four types of facies associations are distinguished within Triassic deep-marine successions: massive and thick-bedded coarse-grained facies association, medium- and thick-bedded sandstone with interlayered fine-grained facies association, interlayered thin-bedded fine-grained facies association, and syn-sedimentary slump/breccia facies association. Spatial distribution of the different facies associations suggests that Lower Triassic sedimentation occurred primarily in continental slope, submarine channels, and base-of-slope aprons in the Hezuo-Jianzha region of the western Qinling, whereas the Middle Triassic consists mainly of sedimentary facies of base-of-slope aprons and submarine incised valleys. The counterparts in the Dangchang-Diebu region, in contrast, are characterized by platform carbonates. The shallow-marine carbonates evolved into deep-marine facies since the Ladinian, indicative of rapid drowning of the Carnian carbonate platform in Middle Triassic times. Depositional history of Lower

  13. Polychlorinated biphenyl (PCB) anaerobic degradation in marine sediments: microcosm study and role of autochthonous microbial communities.

    Science.gov (United States)

    Matturro, Bruna; Ubaldi, Carla; Grenni, Paola; Caracciolo, Anna Barra; Rossetti, Simona

    2016-07-01

    Polychlorobiphenyl (PCB) biodegradation was followed for 1 year in microcosms containing marine sediments collected from Mar Piccolo (Taranto, Italy) chronically contaminated by this class of hazardous compounds. The microcosms were performed under strictly anaerobic conditions with or without the addition of Dehalococcoides mccartyi, the main microorganism known to degrade PCBs through the anaerobic reductive dechlorination process. Thirty PCB congeners were monitored during the experiments revealing that the biodegradation occurred in all microcosms with a decrease in hepta-, hexa-, and penta-chlorobiphenyls (CBs) and a parallel increase in low chlorinated PCBs (tri-CBs and tetra-CBs). The concentrations of the most representative congeners detected in the original sediment, such as 245-245-CB and 2345-245-CB, and of the mixture 2356-34-CB+234-245-CB, decreased by 32.5, 23.8, and 46.7 %, respectively, after only 70 days of anaerobic incubation without any bioaugmentation treatment. Additionally, the structure and population dynamics of the microbial key players involved in the biodegradative process and of the entire mixed microbial community were accurately defined by Catalyzed Reporter Deposition Fluorescence In Situ Hybridization (CARD-FISH) in both the original sediment and during the operation of the microcosm. The reductive dehalogenase genes of D. mccartyi, specifically involved in PCB dechlorination, were also quantified using real-time PCR (qPCR). Our results demonstrated that the autochthonous microbial community living in the marine sediment, including D. mccartyi (6.32E+06 16S rRNA gene copy numbers g(-1) sediment), was able to efficiently sustain the biodegradation of PCBs when controlled anaerobic conditions were imposed. PMID:26162439

  14. In situ lubricant degradation in Antarctic marine sediments. 1. Short-term changes.

    Science.gov (United States)

    Thompson, Belinda A W; Davies, Noel W; Goldsworthy, Paul M; Riddle, Martin J; Snape, Ian; Stark, Jonathan S

    2006-02-01

    A large-scale, in situ experiment was set up near the Bailey Peninsula area (Casey Station, East Antarctica) to monitor the natural attenuation of synthetic lubricants in marine sediments over five years. Here, we report the short-term changes after 5 and 56 weeks. The lubricants tested were an unused and used Mobil lubricant (0W/40; Exxon Mobil, Irving, TX, USA) and a biodegradable alternative (0W/20; Fuchs Lubricants, Harvey, IL, USA). Clean sediment was collected, contaminated with the lubricants, and deployed by divers onto the seabed in a randomized block design. The sampled sediments were analyzed by gas chromatography-flame-ionization detector and gas chromatography-mass spectrometry with selective ion monitoring. The base fluid of all lubricant treatments did not decrease significantly after 56 weeks in situ. Alkanoate esters of 1,1,1-tris(hydroxymethyl)propane in the biodegradable and unused lubricants were degraded extensively in situ; however, these esters constituted only a minor proportion of the lubricant volume. The additives, alkylated naphthalenes and substituted diphenylamines, were fairly resistant to degradation, which is of environmental concern because of their toxicity. The biodegradable lubricant did not break down to recognized biodegradable thresholds and, as such, should not be classified as biodegradable under Antarctic marine conditions. A separate experiment was conducted to determine the influence of sediment preparation and deployment on compound ratios within the lubricants, and we found that preparation and deployment of the contaminated sediments had only a minor effect on compound recovery. Further monitoring of this in situ experiment will provide much needed information about the long-term natural attenuation of lubricants. PMID:16519295

  15. Development of marine sediment bioassays and toxicity tests for monitoring and regulation in Europe

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. Ecotoxicological response of marine organisms to inorganic and organic sediment amendments in laboratory exposures.

    Science.gov (United States)

    Rosen, Gunther; Leather, James; Kan, Jinjun; Arias-Thode, Yolanda Meriah

    2011-10-01

    Experimental materials currently being investigated for use as amendments for the in situ remediation of contaminated sediments were assessed for their potential impacts on marine benthos. Laboratory toxicity tests involving lethal and sublethal endpoints were conducted on sediments amended with apatite, organoclay, chitin, or acetate, with the polychaete Neanthes arenaceodentata, the amphipod Eohaustorius estuarius, and the larval sheepshead minnow Cyprinodon variegatus. Amendments were mixed loosely into uncontaminated or metal-contaminated sediments, and also added inside experimental geotextile mats, at sediment dry weight (dw) concentrations ranging from 0.5% to 10%. The geotextile mats, containing apatite (5 or 10% dw), and/or organoclay (5%) did not result in adverse effects on any of the test organisms. Chitin and acetate, however, repetitively resulted in adverse effects on survival and/or adverse or positive effects on organism growth at concentrations of ≤ 2.5% dw. The adverse effects were attributed to water quality degradation in the exposure vessels (notably ammonia and dissolved oxygen concentration, for chitin and acetate, respectively) as a result of the microbial breakdown of the amendments. For N. arenaceodentata, growth was enhanced in the presence of chitin at concentrations as low as 0.5% sediment dw, which stimulated bacterial growth that may have provided an additional food source for the polychaete. Sediment chitin concentrations of 0.5% resulted in a statistically significant reduction in N. arenaceodentata body burdens of 61%, 29%, and 54%, relative to unamended contaminated sediment, for Cu, Zn, and Cd, respectively. The studies suggest a lack of inherent toxicity of these materials on the experimental organisms, as the adverse or positive responses observed are likely related to artifacts associated with laboratory exposure. Assessments in field settings are needed to verify this conclusion. PMID:21840599

  17. Sediment ages and flux variations from depth profiles of 210Pb: lake and marine examples

    International Nuclear Information System (INIS)

    Sediment accumulation rates are redetermined for several freshwater and marine settings to demonstrate the application of a new methodology for interpreting sediment core profiles of radioisotope activity versus depth. Depositional histories were reconstructed using the sediment isotope tomography (SIT) methodology, which abandons the stringent requirement of current methods that sediment accumulation rates and isotopic fluxes may not both vary with time. Using inverse numerical analysis techniques in conjunction with a predictive model, the SIT method is able to separate the effects of sediment accumulation from flux variations to determine age-to-depth relationships. Cumulative probability procedures provide a framework for interpreting the sensitivity and accuracy of the model-determined age-to-depth relationships. Restrictions applied to previous methods on interpreting sediment profiles affected by mixing must also be adhered to when using the SIT method. Previously published data from two Estonian lakes, Kurtna and Nommejaerv, from Rockwell Reservoir in Northeastern Ohio and from Cape Lookout Bight, NC, are examined to demonstrate the broad applicability of the methodology. With the exception of one location, the resultant age-to-depth relationships determined by the model agree with earlier interpretations. In the Estonian Lake Nommejaerv, previous use of the Constant Flux model overestimates sediment ages for two known time horizons, giving ages of 43 yr at 22 cm and 111 yr at 45 cm. The age-to-depth relationship determined by the SIT method reproduces satisfactorily the time horizons of 16±1 yr at 22 cm and 35±2 yr at 45 cm, in agreement with the onset of industrial activities in the region. These examples illustrate the suitability of this new methodology for application in a variety of complex depositional environments

  18. Genotoxic and teratogenic potential of marine sediment extracts investigated with comet assay and zebrafish test

    International Nuclear Information System (INIS)

    Organic extracts of marine sediments from the North Sea and the Baltic Sea were investigated with two toxicity assays. The comet assay based on the fish cell line Epithelioma papulosum cyprini (EPC) was applied to determine the genotoxic potential; zebrafish embryos (Danio rerio) were used to quantify the teratogenic potential of the samples. EC50 values were calculated from dose-response curves for both test systems. Highest teratogenic and genotoxic effects normalised to total organic carbon (TOC) content were detected in sediment samples of different origins. Polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) are not likely to be the causes of the observed effects, as demonstrated by a two-step fractionation procedure of selected extracts. The toxic potential was more pronounced in fractions having polarity higher than those possessed by PAHs and PCBs. The suitability of the two in vitro test systems for assessing genotoxic and teratogenic effects of marine sediment extracts could be demonstrated. - Capsule: In vitro toxicity assays are used to assess genotoxic and teratogenic effects of environmental extracts

  19. Effect of salinity on methanogenic propionate degradation by acclimated marine sediment-derived culture.

    Science.gov (United States)

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

    2015-12-01

    Degradation of propionate under high salinity is needed for biomethane production from salt-containing feedstocks. In this study, marine sediment-derived culture was evaluated to determine the effect of salinity on methanogenic propionate degradation. Microbes in marine sediments were subjected to fed-batch cultivation on propionate for developing acclimatized cultures. The rate of propionate degradation increased eightfold during 10 rounds of cultivation. Microbial community composition was determined through pyrosequencing of 16S rRNA gene amplicons after 10 rounds of cultivation. Taxa analysis was conducted for the reads obtained by pyrosequencing. Known propionate degraders were undetectable in the acclimated culture. Comparison of bacterial taxa in the original sediment with those in the acclimated culture revealed that the populations of four bacterial taxa were significantly increased during acclimation. Methanolobus was the predominant archaea genus in the acclimated culture. The propionate degradation rate of the acclimated culture was not affected by salinity of up to equivalent of 1.9 % NaCl. The rate decreased at higher salinity levels and was more than 50 % of the maximum rate even at equivalent of 4.3 % NaCl. PMID:26364311

  20. Multi-elemental analysis of marine sediments of Manila Bay using x-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    An analysis of the marine sediments of Manila Bay was done by employing X-ray fluorescence spectrometry. The general trends observed in sediments are increasing (Ca and Sr), decreasing (Zr), or constant (Cl, Na, S, K) with respect to depth, sometimes, no trend can be observed. These trends are further explained by correlations present among these elements, plus all the other elements. The two X RF data analysis methods Auto Quantify and AXIL were also compared on the basis of the correlation plot obtained. AutoQuantify gave clearer correlations; thus, results from this method were used for constructing correlation plots. Correlations using Microsoft Excel and Stat graphics Centurion X V show that there are naturally occurring [lithogenic (Si, Ti, Al, Mg, Rb, Zn and Fe), biogenic (Ca, Mg), and conservative (Na, Cl)] and non-naturally occurring [mostly anthropogenic, brought to the bodies of water by aeolian or fluvial input (heavy metals Pb-Cu-Zn and Ni-Cr)] correlation present in the sediments. Moreover, pairs of elements that may coexist in a source and not coexist in another (Cr and Mg, Cr and Ni) have also been observed. The heavy metal enrichment was attributed to the burning of fossil fuels, iron and steel manufacturing (present in Valenzuela-Bulacan area), ferry and fishing services and other industrialization activities present in Manila Bay. Marine organisms are affected by the presence of these heavy metals by means of bioaccumulations, and may later on affect humans because of trophic transfer and bio magnification. (author)

  1. Diversity and distribution of fungal communities in the marine sediments of Kongsfjorden, Svalbard (High Arctic)

    Science.gov (United States)

    Zhang, Tao; Fei Wang, Neng; Qin Zhang, Yu; Yu Liu, Hong; Yan Yu, Li

    2015-10-01

    This study assessed the diversity and distribution of fungal communities in eight marine sediments of Kongsfjorden (Svalbard, High Arctic) using 454 pyrosequencing with fungal-specific primers targeting the internal transcribed spacer (ITS) region of the ribosomal rRNA gene. Sedimentary fungal communities showed high diversity with 42,219 reads belonging to 113 operational taxonomic units (OTUs). Of these OTUs, 62 belonged to the Ascomycota, 26 to Basidiomycota, 2 to Chytridiomycota, 1 to Zygomycota, 1 to Glomeromycota, and 21 to unknown fungi. The major known orders included Hypocreales and Saccharomycetales. The common fungal genera were Pichia, Fusarium, Alternaria, and Malassezia. Interestingly, most fungi occurring in these Arctic sediments may originate from the terrestrial habitats and different basins in Kongsfjorden (i.e., inner basin, central basin, and outer basin) harbor different sedimentary fungal communities. These results suggest the existence of diverse fungal communities in the Arctic marine sediments, which may serve as a useful community model for further ecological and evolutionary study of fungi in the Arctic.

  2. Ecological and isotopic insights to the origin of archaeal tetraethers in marine sediments

    Science.gov (United States)

    Pearson, A.; Hurley, S. J.

    2012-12-01

    Thaumarchaeota, formerly known as Marine Group I Crenarchaeota, are believed to be the primary source of the isoprenoidal glycerol dialkyl glycerol tetraether lipids (GDGTs) found in the environment. Enrichment mesocosms and empirical correlations for marine sediments (TEX86) show a positive relationship between environmental temperature and the number of cyclopentyl or cyclohexyl rings contained within the GDGT structure. The TEX86 paleotemperature proxy has been applied across a large temporal range of geologic events and to sediments of widely varying depositional and diagenetic history. TEX86 assumes a direct correlation between the preserved GDGT ratios and SST. A number of fundamental assumptions underlie this correlation, including that: (1) GDGTs transported to the sediments reflect biomass of surface origin, (2) GDGTs produced by Archaea deeper in the water column should reflect deep temperatures and are not exported, and (3) community variations - including the potential contribution of GDGTs by Group II Euryarchaeota - do not appreciably affect the overall TEX86-SST relationship. Here we discuss evidence that questions all three of these assumptions and propose strategies for further understanding how GDGTs record paleoenvironments. These new approaches include greater application of physiological and culture studies; concurrent measurements of δ13C, Δ14C and D/H ratios of GDGTs; and cross-correlations with other paleotemperature proxies.

  3. Studies of anoxiC conditions in Framvaren fjord, Gullmaren fjord and Byfjorden and of mixing between seawater and freshwater at the Kalix river and estuary

    International Nuclear Information System (INIS)

    The sediments in the anoxic Framvaren fjord acts as a source for actinides to the overlaying water column. The remobilisation process is most likely linked to early diagenetic alteration of the marine organic material in the sediments. This is indicated by the close correlation between Pu, Am and dissolved organic carbon depth profiles in the water column. Speciation studies of the plutonium and americium in the water column shows that both to a large degree are associated to colloidal material in the size range 0.01-0.45 μm. Less than 2% is retained by a 0.45 μm filter which is reflected in the low KD-values obtained of about 20 000, which is at least a factor of 10 lower than in typical coastal waters. It is also proven that the plutonium exist almost entirely in the trivalent state in the anoxic water column. This study is the first ever to show extensive remobilisation of plutonium and americium from sediments in anoxic marine basins. Similar remobilisation from sediments most likely occur in other anoxic marine waters where early diagenesis results in humic and fulvic acid production. Although the remobilised actinides in the Framvaren fjord at present don't pose any radiological hazard due to the lack of fish in anoxic waters, it is of great concern to identify processes involved in the remobilisation of actinides from anoxic sediments as such sediments likely will be a major source for actinides in the Baltic Sea and other oxygen sensitive basins in the long term perspective. In such basins the remobilised plutonium may reach oxygenated and biological productive waters by convection. Results from the temporarily oxygen deficient Gullmaren fjord on the Swedish west coast shows that remobilisation from sediments can not be identified during short (a few months) periods of oxygen deficient water. The rapid bioturbation (quantified by tracer studies) in this fjord results in that sedimenting organic material rapidly is buried and distributed within the upper

  4. Studies of anoxiC conditions in Framvaren fjord, Gullmaren fjord and Byfjorden and of mixing between seawater and freshwater at the Kalix river and estuary

    Energy Technology Data Exchange (ETDEWEB)

    Roos, P. [Univ. of Lund, Lund (Sweden)

    2001-04-01

    The sediments in the anoxic Framvaren fjord acts as a source for actinides to the overlaying water column. The remobilisation process is most likely linked to early diagenetic alteration of the marine organic material in the sediments. This is indicated by the close correlation between Pu, Am and dissolved organic carbon depth profiles in the water column. Speciation studies of the plutonium and americium in the water column shows that both to a large degree are associated to colloidal material in the size range 0.01-0.45 {mu}m. Less than 2% is retained by a 0.45 {mu}m filter which is reflected in the low K{sub D}-values obtained of about 20 000, which is at least a factor of 10 lower than in typical coastal waters. It is also proven that the plutonium exist almost entirely in the trivalent state in the anoxic water column. This study is the first ever to show extensive remobilisation of plutonium and americium from sediments in anoxic marine basins. Similar remobilisation from sediments most likely occur in other anoxic marine waters where early diagenesis results in humic and fulvic acid production. Although the remobilised actinides in the Framvaren fjord at present don't pose any radiological hazard due to the lack of fish in anoxic waters, it is of great concern to identify processes involved in the remobilisation of actinides from anoxic sediments as such sediments likely will be a major source for actinides in the Baltic Sea and other oxygen sensitive basins in the long term perspective. In such basins the remobilised plutonium may reach oxygenated and biological productive waters by convection. Results from the temporarily oxygen deficient Gullmaren fjord on the Swedish west coast shows that remobilisation from sediments can not be identified during short (a few months) periods of oxygen deficient water. The rapid bioturbation (quantified by tracer studies) in this fjord results in that sedimenting organic material rapidly is buried and distributed

  5. Reconstruction of the West Pacific ENSO precipitation anomaly using the compound-specific hydrogen isotopic record of marine lake sediments of Palau

    Science.gov (United States)

    Smittenberg, R. H.; Sachs, J. P.; Dawson, M. N.

    2004-12-01

    There is still much uncertainty whether the El Niño Southern Oscillation (ENSO) will become stronger or more frequent in a warming global climate. A principal reason for this uncertainty stems from a glaring lack of paleoclimate data in the equatorial Pacific, which hampers model validation. To partly resolve this data deficiency, sediments of three marine anoxic lakes were cored in Palau, an island group that lies in the heart of the West Pacific Warm Pool. The lakes contain seawater that seeps through fissures in the surrounding karst, and they are permanently stratified due to fresh water input provided by the year-round wet climate (map 1970-2000 = 3.7m). During ENSO events, however, the islands suffer from drought. The surface water hydrogen isotopic compositions in the lakes are sensitive to the relative proportions of D-depleted rainwater and D-enriched seawater, and are therefore sensitive to ENSO events. The lake surface water H/D values are recorded by algal and bacterial biomarkers that are preserved well in the highly organic and anoxic sediments, which accumulate relatively fast (mean 1 mm/yr). Ongoing down core measurement will eventually result in a precipitation proxy record of the islands. To obtain endmember D/H values, a comprehensive set of water samples from sea, lakes and rain water was obtained, as well as suspended particulate matter. Higher plant biomarker D/H values derived from the jungle vegetation surrounding the lakes may render supporting climatic proxy data, being influenced by evapotranspiration. Some lakes are inhabited by millions of jellyfish (Mastigias) that live in symbiosis with zooxanthellae. The jellyfish of one of the investigated lakes disappeared completely after the last large ENSO event in 1998 (returning in 2000-01), and a correlation is suggested. To reconstruct the history of jellyfish occurrence, jellyfish and sedimentary lipids were extracted and compared. In addition to a possible ENSO proxy record, this

  6. The Surface of Venus is Saturated With Ancient Impact Structures, and its Plains are Marine Sediments

    Science.gov (United States)

    Hamilton, W. B.

    2009-05-01

    Conventional interpretations of Venus are forced to fit dubious pre-Magellan conjectures that the planet is as active internally as Earth and preserves no ancient surface features. Plate tectonics obviously does not operate, so it is commonly assumed that the surface must record other endogenic processes, mostly unique to Venus. Imaginative systems of hundreds of tiny to huge rising and sinking plumes and diapirs are invoked. That much of the surface in fact is saturated with overlapping large circular depressions with the morphology of impact structures is obscured by postulating plume origins for selected structures and disregarding the rest. Typical structures are rimmed circular depressions, often multiring, with lobate debris aprons; central peaks are common. Marine-sedimentation features are overlooked because dogma deems the plains to be basalt flows despite their lack of source volcanoes and fissures. The unearthly close correlation between geoid and topography at long to moderate wavelengths requires, in conventional terms, dynamic maintenance of topography by up and down plumes of long-sustained precise shapes and buoyancy. A venusian upper mantle much stronger than that of Earth, because it is cooler or poorer in volatiles, is not considered. (The unearthly large so-called volcanoes and tessera plateaus often are related to rimmed circular depressions and likely are products of impact fluidization and melting.) Plains-saturating impact structures (mostly more obvious in altimetry than backscatter) with diameters of hundreds of km are superimposed as cookie-cutter bites, are variably smoothed and smeared by apparent submarine impact and erosion, and are differentially buried by sediments compacted into them. Marine- sedimentation evidence includes this compaction; long sinuous channels and distributaries with turbidite- channel characteristics and turbidite-like lobate flows (Jones and Pickering, JGSL 2003); radar-smooth surfaces and laminated aspect in

  7. Thaumarchaeotal Signature Gene Distribution in Sediments of the Northern South China Sea: an Indicator of the Metabolic Intersection of the Marine Carbon, Nitrogen, and Phosphorus Cycles?

    OpenAIRE

    Dang, Hongyue; ZHOU, Haixia; Yang, Jinying; Ge, Huangmin; Jiao, Nianzhi; Luan, Xiwu; Zhang, Chuanlun; Martin G Klotz

    2013-01-01

    Thaumarchaeota are abundant and active in marine waters, where they contribute to aerobic ammonia oxidation and light-independent carbon fixation. The ecological function of thaumarchaeota in marine sediments, however, has rarely been investigated, even though marine sediments constitute the majority of the Earth's surface. Thaumarchaeota in the upper layer of sediments may contribute significantly to the reservoir of nitrogen oxides in ocean waters and thus to productivity, including the ass...

  8. INFLUENCE OF SOOT CARBON ON THE BIOACCULUMATION OF SEDIMENT-BOUND POLYCYCLIC AROMATIC HYDROCARBONS BY MARINE BENTHIC INVERTEBRATES: AN INTERSPECIES COMPARISON

    Science.gov (United States)

    The sorption of polycyclic aromatic hydrocarbons (PAHs) to soot carbon in marine sediments has been hypothesized to reduce PAH bioavailability. This hypothesis was tested for eight species of marine benthic invertebrates (four polychaete worms, Clymenella torquata, Nereis virens,...

  9. Tsunami induced transportation of the coastal marine sediments to distant onshore regions: Some indications from foraminiferal and microbenthic studies of new Wandoor region (Andaman & Nicobar)

    Digital Repository Service at National Institute of Oceanography (India)

    Khare, N.; Chaturvedi, S.K.; Ingole, B.S.

    regions near New Wandoor (Andaman and Nicobar) suggested the areal extent of marine transgression due to tsunami waves on December 26, 2004. There is a need to investigate coastal marine sediments with multi-disciplinary approach to understnd impact...

  10. Integrated ecotoxicological assessment of marine sediments affected by land-based marine fish farm effluents: physicochemical, acute toxicity and benthic community analyses.

    Science.gov (United States)

    Silva, C; Yáñez, E; Martín-Díaz, M L; Riba, I; DelValls, T A

    2013-08-01

    An integrated ecotoxicological assessment of marine sediments affected by land-based marine fish farm effluents was developed using physicochemical and benthic community structure analyses and standardised laboratory bioassays with bacteria (Vibrio fischeri), amphipods (Ampelisca brevicornis) and sea urchin larvae (Paracentrotus lividus). Intertidal sediment samples were collected at five sites of the Rio San Pedro (RSP) creek, from the aquaculture effluent to a clean site. The effective concentration (EC50) from bacterial bioluminescence and A. brevicornis survival on whole sediments and P. lividus larval developmental success on sediment elutriates were assessed. Numbers of species, abundance and Shannon diversity were the biodiversity indicators measured in benthic fauna of sediment samples. In parallel, redox potential, pH, organic matter and metal levels (Cd, Cu, Ni, Pb and Zn) in the sediment and dissolved oxygen in the interstitial water were measured in situ. Water and sediment physicochemical analysis revealed the exhibition of a spatial gradient in the RSP, evidenced by hypoxia/anoxia, reduced and acidic conditions, high organic enrichment and metal concentrations at the most contaminated sites. Whereas, the benthic fauna biodiversity decreased the bioassays depicted decreases in EC50, A. brevicornis survival, P. lividus larval success at sampling sites closer to the studied fish farms. This study demonstrates that the sediments polluted by fish farm effluents may lead to alterations of the biodiversity of the exposed organisms. PMID:23681739

  11. The Temporal and Spatial Distribution of Foraminiferans in Marine Benthic Sediments of the Clyde Sea Area, Scotland

    Science.gov (United States)

    Hannah, F.; Rogerson, A.

    1997-03-01

    The numbers of benthic foraminiferans at four sites in the Clyde Sea area showed no consistent temporal variation throughout 1993. In the finest surface sediments, numbers ranged between 200 and 400 cells cm -3, compared to only 25-50 cells cm -3in the coarsest sediments. On two occasions, high populations of cells less than 63 μm were found in the surface layers. These were thought to represent recruitment peaks since these ' juvenile ' cells grew rapidly when maintained in the laboratory. A total of 56 taxa were identified from the region, the greatest diversity being recorded in the finest sediments. Rose Bengal stained foraminiferans (i.e. presumed living) were found below the anoxic-oxic boundary. The fate of these cells was considered by examining their ability to migrate through fine sediments, and their capacity to survive (based on evidence of pseudopodial activity) periods of anoxia. This study has highlighted the numerical importance of foraminiferans, particularly in fine surface coastal sediments, but questions whether the high populations of ' stained ' cells found in deeper sediments play a significant ecological role.

  12. Bioaccumulation and effect of sediment-associated silver in different forms in two marine deposit feeders

    DEFF Research Database (Denmark)

    Dai, Lina; Banta, Gary Thomas; Syberg, Kristian;

    2014-01-01

    to sediment amended with Ag in various forms (ionic Ag(I), nano-sized Ag and micron-sized Ag), and toxic endpoints were assessed at the whole organism level. After exposure for several weeks, no significant toxic effects were detected (i.e., mortality, growth rate and condition index) at the whole...... limited information at the whole organism level as to whether metallo-nanoparticles differ in toxicity from the same metals added to the environment in ionic or bulk form. In the present study, two organisms (i.e., a marine polychaete, Capitella teleta and a marine bivalve, Macoma balthica) were exposed...... organism level, although all forms of metallic Ag were accumulated in our test organisms. Our results thus did not confirm findings from studies performed at the subcellular level that have found the toxicity of Ag nanoparticles was more toxic than the corresponding metallic Ag in ionic and in bulk forms...

  13. A marine to freshwater sediment succession from Kowhai Beach wetland, Northland : implications for Holocene sea level

    International Nuclear Information System (INIS)

    An infilled wetland located behind coastal dunes in north-east Northland is used to reconstruct a local history of environmental change spanning early Holocene (c. 7000 yr BP) to modern time. Proxy indicators (sediment texture, diatoms and pollen) provide evidence for a transition from marginal marine- to brackish- to freshwater-conditions in the wetland. Radiocarbon ages constrain the chronology of this succession to 7880-7430 cal. yr BP for the early period of marine conditions, 3570-3210 cal. yr BP for the latter brackish phase and 1060-800 cal. yr BP for the change to freshwater conditions. Within this succession, the diatom record preserves a strong brackish signal at core depths above the limit of the modern tidal range. This is presented as preliminary evidence for a mid-Holocene sea level highstand for northern New Zealand of approximately 1.2 m above present mean sea level. (author). 40 refs., 7 figs., 1 tab

  14. Uptake of radioactivity by marine surface sediments collected in Ghazaouet, west coast of Algeria

    International Nuclear Information System (INIS)

    Samples of surface marine sediments of different grain sizes collected in Ghazaouet, a small bay on the western coast of Algeria, have been examined to measure concentrations of natural and artificial gamma-emitting radionuclides. The aim of this study is to determine the level of radioactivity and its repartition in the sedimentary area. The samples analyzed by direct counting gamma spectrometry, showed relatively high activities for natural radioactivity and revealed measurable quantities of 137Cs, ranging from 0.66-8.47 Bq kg-1 dry weight. In addition, some of the samples of different nature were sieved in different grain-sizes, to study the uptake of radioactivity. It is found that the sediments of less than 100 μm grain-size have the highest level of uptake of radioactivity

  15. MERCURY RELEASE FROM DISTURBED ANOXIC SOILS

    Energy Technology Data Exchange (ETDEWEB)

    Jaroslav Solc; Bethany A. Bolles

    2001-07-16

    The primary objectives of experiments conducted at the Energy & Environmental Research Center (EERC) were to provide information on the secondary release of mercury from contaminated anoxic sediments to an aqueous environment after disturbance/change of in situ physical conditions and to evaluate its migration and partitioning under controlled conditions, including implications of these processes for treatment of contaminated soils. Experimental work included (1) characterization of the mercury-contaminated sediment; (2) field bench-scale dredging simulation; (3) laboratory column study to evaluate a longer-term response to sediment disturbance; (4) mercury volatilization from sediment during controlled drying; (5) resaturation experiments to evaluate the potential for secondary release of residual mercury after disturbance, transport, drying, and resaturation, which simulate a typical scenario during soil excavation and transport to waste disposal facilities; and (6) mercury speciation and potential for methylation during column incubation experiments.

  16. MERCURY RELEASE FROM DISTURBED ANOXIC SOILS; TOPICAL

    International Nuclear Information System (INIS)

    The primary objectives of experiments conducted at the Energy and Environmental Research Center (EERC) were to provide information on the secondary release of mercury from contaminated anoxic sediments to an aqueous environment after disturbance/change of in situ physical conditions and to evaluate its migration and partitioning under controlled conditions, including implications of these processes for treatment of contaminated soils. Experimental work included (1) characterization of the mercury-contaminated sediment; (2) field bench-scale dredging simulation; (3) laboratory column study to evaluate a longer-term response to sediment disturbance; (4) mercury volatilization from sediment during controlled drying; (5) resaturation experiments to evaluate the potential for secondary release of residual mercury after disturbance, transport, drying, and resaturation, which simulate a typical scenario during soil excavation and transport to waste disposal facilities; and (6) mercury speciation and potential for methylation during column incubation experiments

  17. Rock physics modeling of shallow marine sediments in the eastern continental margin of India

    Digital Repository Service at National Institute of Oceanography (India)

    Dewangan, P.; Sriram, G.; RamPrasad, T.

    that are in a state of suspension, i.e. having no frame stiffness. The EMM model can be extended to estimate the hydrate and free gas concentration in marine sediments from porosity and velocity profiles (Helgerud, 1999). Lee (2006) showed that shear wave... is matrix velocity, V w water velocity and V p Woods velocity. Lee Equation for S-wave prediction: The S-wave velocities can be predicted from the moduli of the dry rock which can be estimated from the P-wave velocity. Dry rock bulk moduli...

  18. Focus on sulfur count rates along marine sediment cores acquired by XRF Core Scanner

    OpenAIRE

    Chéron, Sandrine; Etoubleau, Joel; Bayon, Germain; Garziglia, Sebastien; Boissier, Audrey

    2016-01-01

    The aim of this study is to investigate the information provided by sulfur count rates obtained by X-ray fluorescence core scanner (XRF-CS) along sedimentary records. The analysis of two marine sediment cores from the Niger Delta margin shows that XRF-CS sulfur count rates obtained at the surface of split core sections with XRF-CS correlate with both direct quantitative pyrite concentrations, as inferred from X-ray powder diffraction (XRD) and sulfur determination by wavelength dispersive X-r...

  19. A metagenomic study of methanotrophic microorganisms in Coal Oil Point seep sediments

    OpenAIRE

    Haverkamp Thomas HA; Håvelsrud Othilde; Kristensen Tom; Jakobsen Kjetill S; Rike Anne

    2011-01-01

    Background Methane oxidizing prokaryotes in marine sediments are believed to function as a methane filter reducing the oceanic contribution to the global methane emission. In the anoxic parts of the sediments, oxidation of methane is accomplished by anaerobic methanotrophic archaea (ANME) living in syntrophy with sulphate reducing bacteria. This anaerobic oxidation of methane is assumed to be a coupling of reversed methanogenesis and dissimilatory sulphate reduction. Where ...

  20. Spatiotemporal distributions of Fukushima-derived radionuclides in nearby marine surface sediments

    Directory of Open Access Journals (Sweden)

    M. Kusakabe

    2013-07-01

    Full Text Available Spatiotemporal distributions of anthropogenic radionuclides in marine surface sediments off Miyagi, Fukushima, and Ibaraki Prefectures were analyzed on the basis of data collected during the monitoring program launched by the Japanese Ministry of Education, Sports, Science and Technology in 2011 right after the Fukushima Dai-ichi Nuclear Power Plant accident began. Concentrations of 137Cs in the surface sediments varied spatially by two orders of magnitude, from 1.7 to 580 Bq kg-dry−1, and there was no obvious correlation between 137Cs concentration and the proximity of the sampling location to the accident site. The total inventory of 137Cs accumulated in the upper 3 cm of surface sediments in the monitoring area was estimated to be 3.78 × 1013 Bq, that is, 0.1–2% of the total 137Cs flux from the plant to the ocean as a result of the accident (the percentage depends on the model used to estimate the total flux. The spatial variations of 137Cs concentration and inventory depended on two main factors: the 137Cs concentration in the overlying water during the first several months after the accident and the physical characteristics of the sediments (water content and bulk density. The temporal variations of the concentrations of other anthropogenic radionuclides (90Sr, 95Nb, 110 mAg, 125Sb, 129Te, and 129 mTe in the sediments were also investigated. Activity ratios of these nuclides to 137Cs suggest that the nuclides themselves were not homogenized before they were removed from seawater to the sediments.

  1. Transformation of PBDE mixtures during sediment transport and resuspension in marine environments (Gulf of Lion, NW Mediterranean Sea)

    International Nuclear Information System (INIS)

    Polybromodiphenyl ethers (PBDEs) in superficial sediments from the Gulf of Lion were studied. They were largely predominated by BDE 209 (98.7% of all PBDEs) indicating that the main source of these pollutants was the commercial mixture deca-BDE. This compound and the less brominated BDE exhibited a southwestward decreasing concentration gradient following the dominant marine currents and bottom relief, e.g. the Mud Belt, the submarine canyons and the Open Continental Slope. All PBDEs exhibited statistically significant correlations confirming the common origin. However, a progressive transformation of the dumped BDE 209 was identified showing a depletion paralleled by increases of the less brominated BDEs (from 8.6% to 22%). These less brominated compounds were accumulated at about 100–140 km away from the Rhone prodelta, e.g. at the end of the submarine canyons, evidencing that these transformation compounds can be accumulated at long distances from the dumping sites in the marine system. Highlights: ► Polybromodiphenyl ethers are associated to organic carbon in marine sediments. ► PBDEs in marine sediments can accumulate further away than 140 km from the spill site. ► BDE-209 in marine sediments generate congeners found in banned commercial mixtures. ► BDE-209 in marine sediments generates new congeners not found in commercial mixtures. ► Submarine canyons channel PBDEs from the continental platform to the deep shelf. - Decomposition of decabromodiphenyl ether in marine sediments generates congeners found in banned mixtures in areas located far away from the discharge sites.

  2. Simulating the modern δ30Si distribution in the oceans and in marine sediments

    Science.gov (United States)

    Gao, S.; Wolf-Gladrow, D. A.; Völker, C.

    2016-02-01

    The δ30Si of biogenic silica (δ30SiBSi) in marine sediments is a promising proxy for the reconstruction of silicic acid utilization by diatoms in the geological past. The application of this proxy, however, requires an understanding of the modern δ30Si distributions and their controlling mechanisms. Here we present results from a modern climate simulation with a coupled ocean-sediment model that includes a prognostic formulation of biogenic silica production with concurrent silicon isotopic fractionation. In agreement with previous studies, biological fractionation combined with physical transport and mixing determines the oceanic distribution of simulated δ30Si. A new finding is a distinct seasonal cycle of δ30Si in the surface ocean, which is inversely related to that of silicic acid concentration and mixed layer depth. We also provide the first simulation results of sedimentary δ30Si, which reveal that (1) the δ30SiBSi distribution in the surface sediment reflects the exported δ30SiBSi signal from the euphotic zone and (2) the dissolution of biogenic silica in the sediment acts as a source of relatively light δ30Si into the bottom waters of the polar oceans, while it is a source of heavier δ30Si to the subtropical South Atlantic and South Pacific.

  3. Ligand-enhanced electrokinetic remediation of metal-contaminated marine sediments with high acid buffering capacity.

    Science.gov (United States)

    Masi, Matteo; Iannelli, Renato; Losito, Gabriella

    2016-06-01

    The suitability of electrokinetic remediation for removing heavy metals from dredged marine sediments with high acid buffering capacity was investigated. Laboratory-scale electrokinetic remediation experiments were carried out by applying two different voltage gradients to the sediment (0.5 and 0.8 V/cm) while circulating water or two different chelating agents at the electrode compartments. Tap water, 0.1 M citric acid and 0.1 M ethylenediaminetetraacetic acid (EDTA) solutions were used respectively. The investigated metals were Zn, Pb, V, Ni and Cu. In the unenhanced experiment, the acid front could not propagate due to the high acid buffering capacity of the sediments; the production of OH(-) ions at the cathode resulted in a high-pH environment causing the precipitation of CaCO3 and metal hydroxides. The use of citric acid prevented the formation of precipitates, but solubilisation and mobilisation of metal species were not sufficiently achieved. Metal removal was relevant when EDTA was used as the conditioning agent, and the electric potential was raised up to 0.8 V/cm. EDTA led to the formation of negatively charged complexes with metals which migrated towards the anode compartment by electromigration. This result shows that metal removal from sediments with high acid buffering capacity may be achieved by enhancing the electrokinetic process by EDTA addition when the acidification of the medium is not economically and/or environmentally sustainable. PMID:26490900

  4. Characterization of trace organic contaminants in marine sediment from Yeongil Bay, Korea: 1. Instrumental analyses

    International Nuclear Information System (INIS)

    Concentrations of polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides (HCB, HCHs, CHLs, and DDTs), polycyclic aromatic hydrocarbons (PAHs), alkylphenols (APs), and bisphenol A (BPA) were measured in 26 marine sediments collected from Yeongil Bay, Korea, in order to characterize their spatial distribution and sources. PCBs (2.85-26.5 ng/g, dry wt.) were detected mainly in the inner bay locations Mean OC pesticide ranged from 1.16 ng/g dry wt. for HCH to 0.05 ng/g dry wt. for HCB). PAH concentrations ranged from <10.0 to 1870 (mean: 309) ng/g dry wt., and were predominated 3- and 4-ring congeners. Concentrations of APs, such as nonylphenol, octylphenol, butylphenol (means 89.1, 4.61, 11.0 ng/g dry wt., respectively), were greater at locations proximal to municipal wastewater discharges. Concentrations of PCBs and PAHs were great near shipyards and industrial complexes. Vertical profiles of PAHs and APs indicated that they have been associated with sediments since the 1950s. - Among various sediment contaminant classes measured, nonylphenol and PAHs are responsible for the variability among sampling sites, suggesting the existence of multiple sources in Yeongil Bay sediment

  5. Numerical simulation of sealing effect of gas hydrate for CO2 leakage in marine sediment

    Science.gov (United States)

    Sato, T.; Yu, T.; Oyama, H.; Yoshida, T.; Nakashima, T.; Kamada, K.

    2015-12-01

    Although carbon dioxide capture and storage in subsea geological structure is regarded as one of the promising mitigation technologies against the global warming, there is a risk of CO2 leakage and it is required to develop numerical models to predict how the CO2 migrate in the marine sediments. It is said that there are CO2-trap mechanisms in the geological formations, such as capillary trap, dissolution trap, and mineral trap. In this study, we focus on another trap mechanism: namely, hydrate trap. If the water is deep in the ocean, say more than 250 m, CO2 hydrate forms near the sea floor, at which temperature and pressure conditions can stabilise CO2 hydrate. To predict the gas productivity, it is important to know permeability damage in hydrate bearing sediments. Although hydrate saturation is the same, the permeability is different depending on its spatial distribution within the pore of sand sediment. Here, to know where hydrate is formed in the pore of porous media, we propose a numerical model for estimating the microscopic distribution of CO2 hydrate in sand sediment using a classical nucleation theory and the phase-field model.

  6. Optimizing sample pretreatment for compound-specific stable carbon isotopic analysis of amino sugars in marine sediment

    Directory of Open Access Journals (Sweden)

    R. Zhu

    2014-01-01

    Full Text Available Amino sugars are quantitatively significant constituents of soil and marine sediment, but their sources and turnover in environmental samples remain poorly understood. The stable carbon isotopic composition of amino sugars can provide information on the lifestyles of their source organisms and can be monitored during incubations with labeled substrates to estimate the turnover rates of microbial populations. However, until now, such investigation has been carried out only with soil samples, partly because of the much lower abundance of amino sugars in marine environments. We therefore optimized a procedure for compound-specific isotopic analysis of amino sugars in marine sediment employing gas chromatography-isotope ratio mass spectrometry. The whole procedure consisted of hydrolysis, neutralization, enrichment, and derivatization of amino sugars. Except for the derivatization step, the protocol introduced negligible isotopic fractionation, and the minimum requirement of amino sugar for isotopic analysis was 20 ng, i.e. equivalent to ~ 8 ng of amino sugar carbon. Our results obtained from δ13C analysis of amino sugars in selected marine sediment samples showed that muramic acid had isotopic imprints from indigenous bacterial activities, whereas glucosamine and galactosamine were mainly derived from organic detritus. The analysis of stable carbon isotopic compositions of amino sugars opens a promising window for the investigation of microbial metabolisms in marine sediments and the deep marine biosphere.

  7. Oil effect in freshly spiked marine sediment on Vibrio fischeri, Corophium volutator, and Echinocardium cordatum.

    Science.gov (United States)

    Brils, Jos M; Huwer, Sherri L; Kater, Belinda J; Schout, Peter G; Harmsen, Joop; Delvigne, Gerard A L; Scholten, Martin C Th

    2002-10-01

    The purpose of this study was to provide data to be used in The Netherlands for development of ecotoxicologically based quality criteria for oil-contaminated sediments and dredged material. In addition, the relation of toxicity to specific oil boiling-point fraction ranges was explored. Natural marine sediment, with a moisture, organic carbon, and silt content of approximately 80, 1.8, and 33% of the dry weight, respectively, was artificially spiked using a spiking method developed in this project. Aliquots of one part of the sediment were spiked to several concentrations of Gulf distillate marine grade A (DMA) gasoil (containing 64% C10-19) and aliquots of the other part to several concentrations of Gulf high viscosity grade 46 (HV46) hydraulic oil (containing 99.2% C19-40). Thus, for each individual oil type, a concentration series was created. Vibrio fischeri (endpoint: bioluminescence inhibition), Corophium volutator (endpoint:mortality), and Echinocardium cordatum (endpoint:mortality) were exposed to these spiked sediments for 10 min, 10 d and 14 d, respectively. Based on the test results, the effective concentration on 50% of the test animals was statistically estimated. For DMA gasoil and HV46 hydraulic oil, respectively, the effective concentrations were 43.7 and 2,682 mg/kg dry weight for V. fischeri, 100 and 9,138 mg/kg dry weight for C. volutator, 190, and 1064 mg/kg dry weight for E. cordatum. This study shows that the toxicity is strongly correlated with the lower boiling-point fractions and especially to those within the C10-C19 range. PMID:12371504

  8. Correction of sound velocity depending on the temperature for unconsolidated marine sediment

    Science.gov (United States)

    Kim, Dae-Choul

    2016-04-01

    laboratory sound velocity measurements with systematic temperature change on unconsolidated marine sediment have been performed to establish the precise correction curves between temperature and the sound velocity. Piston and box core samples recovered from the East Sea and the South Sea of Korea were used for the measurement. The core samples were cooled (at temperature of nearly 0℃) and the temperature was gradually increased (from 0℃ to 30℃) to measure sound velocity depending on the changes in temperature. The sediment texture and physical properties (porosity, water content, and bulk density) were measured separately at the same depth. The rate of velocity increase for muddy, silty, and sandy sediment are about 2.63 m/s/℃, 2.74 m/s/℃, and 2.96 m/s/℃, respectively. This is similar to the velocity change rate, 2.97 m/s/℃ presented by Del Grosso (1952). The samples used in this research, however, have relatively higher porosity than those of Del Grosso (1952). Thus, the possibility of discrepancy is differences in water content which affect the sound velocity and measurement system. We used recently developed digital velocity measurement system using PXI based on LabVIEW. We suggest to employ this correction for the accurate in situ geoacoustic property from laboratory data particularly for the deep cold water sample such as the East Sea sediment that has very low bottom water temperature about 0℃. Keywords : in situ geoacoustic property, temperature correction, East Sea Acknowledgements: This research was supported by the Agency for Defense Development (UD14003DD) and by "Marine geological and geophysical mapping of the Korean seas" of the Korea Institute of Geoscience and Mineral Resources (KIGAM).

  9. Stable carbon isotope ratios of intact GDGTs indicate heterogeneous sources to marine sediments

    Science.gov (United States)

    Pearson, Ann; Hurley, Sarah J.; Walter, Sunita R. Shah; Kusch, Stephanie; Lichtin, Samantha; Zhang, Yi Ge

    2016-05-01

    Thaumarchaeota, the major sources of marine glycerol dibiphytanyl glycerol tetraether lipids (GDGTs), are believed to fix the majority of their carbon directly from dissolved inorganic carbon (DIC). The δ13C values of GDGTs (δ13CGDGT) may be powerful tools for reconstructing variations in the ocean carbon cycle, including paleoproductivity and water mass circulation, if they can be related to values of δ13CDIC. To date, isotope measurements primarily are made on the C40 biphytane skeletons of GDGTs, rather than on complete tetraether structures. This approach erases information revealed by the isotopic heterogeneity of GDGTs within a sample and may impart an isotopic fractionation associated with the ether cleavage. To circumvent these issues, we present δ13C values for GDGTs from twelve recent sediments representing ten continental margin locations. Samples are purified by orthogonal dimensions of HPLC, followed by measurement of δ13C values by Spooling Wire Microcombustion (SWiM)-isotope ratio mass spectrometry (IRMS) with 1σ precision and accuracy of ±0.25‰. Using this approach, we confirm that GDGTs, generally around -19‰, are isotopically "heavy" compared to other marine lipids. However, measured δ13CGDGT values are inconsistent with predicted values based on the 13C content of DIC in the overlying water column and the previously-published biosynthetic isotope fractionation for a pure culture of an autotrophic marine thaumarchaeon. In some sediments, the isotopic composition of individual GDGTs differs, indicating multiple source inputs. The data appear to confirm that crenarchaeol primarily is a biomarker for Thaumarchaeota, but its δ13C values still cannot be explained solely by autotrophic carbon fixation. Overall the complexity of the results suggests that both organic carbon assimilation (ca. 25% of total carbon) and multiple source(s) of exogenous GDGTs (contributing generally <30% of input to sediments) are necessary to explain the observed

  10. Arctic black shale formation during Cretaceous Oceanic Anoxic Event 2

    DEFF Research Database (Denmark)

    Lenniger, Marc; Nøhr-Hansen, Henrik; Hills, Len V.; Bjerrum, Christian J.

    2014-01-01

    The Late Cretaceous Oceanic Anoxic Event 2 (OAE2) represents a major perturbation of the global carbon cycle caused by the widespread deposition of organic-rich black shales. Although the paleoceanographic response and the spatial extent of bottom-water anoxia in low and mid-paleolatitudes are...... is contemporaneous with the widely observed occurrence of black shale deposition during OAE2. Paleontological, lithological, and geochemical data indicate normal marine conditions with persistent anoxic bottom waters during OAE2. The results imply that the high marine primary productivity pulse...

  11. Bioakkumulering av miljøgifter fra marine sediment - etablering av et test-system. (Bioaccumulation of sediment-bound contaminants - establishment of a test-system)

    OpenAIRE

    Hylland, K.

    1996-01-01

    Det har blitt etablert et oppsett for testing av biotilgjengeligheten av miljøgifter i marine sedimenter. Test-systemet kan brukes til testing av sediment innhentet fra felt og sediment innblandet en ønsket miljøgift eller blanding av miljøgifter. Test-organismer i oppsettet er børstemarken Nereis diversicolor og nettsnegl Hinia (Nassarius) reticulata. Dette er sentrale arter i økosystemet, de er lette å samle i store antall og det er mulig å holde begge i akvariesystemer over lengre tid. All...

  12. Iron Cycling in Marine Sediments - New Insights from Isotope Analysis on Sequentially Extracted Fe Fractions

    Science.gov (United States)

    Henkel, S.; Kasten, S.; Poulton, S.; Hartmann, J.; Staubwasser, M.

    2014-12-01

    Reactive Fe (oxyhydr)oxides preferentially undergo early diagenetic cycling and may cause a diffusive flux of dissolved Fe2+ from sediments towards the sediment-water interface. The partitioning of Fe in sediments has traditionally been studied by applying sequential extractions based on reductive dissolution of Fe minerals. We complemented the sequential leaching method by Poulton and Canfield [1] in order to be able to gain δ56Fe data for specific Fe fractions, as such data are potentially useful to study Fe cycling in marine environments. The specific mineral fractions are Fe-carbonates, ferrihydrite + lepidocrocite, goethite + hematite, and magnetite. Leaching was performed with acetic acid, hydroxylamine-HCl, Na-dithionite and oxalic acid. The processing of leachates for δ56Fe analysis involved boiling the samples in HCl/HNO3/H2O2, Fe precipitation and anion exchange column chromatography. The new method was applied to short sediment cores from the North Sea and a bay of King George Island (South Shetland Islands, Antarctica). Downcore mineral-specific variations in δ56Fe revealed differing contributions of Fe (oxyhydr)oxides to redox cycling. A slight decrease in easily reducible Fe oxides correlating with a slight increase in δ56Fe for this fraction with depth, which is in line with progessive dissimilatory iron reduction [2,3], is visible in the top 10 cm of the North Sea core, but not in the antarctic sediments. Less reactive (dithionite and oxalate leachable) fractions did not reveal isotopic trends. The acetic acid-soluble fraction displayed pronounced δ56Fe trends at both sites that cannot be explained by acid volatile sulfides that are also extracted by acetic acid [1]. We suggest that low δ56Fe values in this fraction relative to the pool of easily reducible Fe oxides result from adsorbed Fe(II) that was open to isotopic exchange with oxide surfaces, affirming the experimental results of Crosby el al. [2]. Hence, δ56Fe analyses on marine

  13. Batch and column studies of the stabilization of toxic heavy metals in dredged marine sediments by hematite after bioremediation.

    Science.gov (United States)

    Mamindy-Pajany, Yannick; Geret, Florence; Hurel, Charlotte; Marmier, Nicolas

    2013-08-01

    The management of dredged sediments is an important issue in coastal regions where the marine sediments are highly polluted by metals and organic pollutants. In this paper, mineral-based amendments (hematite, zero-valent iron and zeolite) were used to stabilize metallic pollutants (As, Cd, Cu, Mo, Ni, Pb, and Zn) in a contaminated marine sediment sample. Mineral-based amendments were tested at three application rates (5 %, 10 %, and 15 %) in batch experiments in order to select the best amendment to perform column experiments. Batch tests have shown that hematite was the most efficient amendment to stabilize inorganic pollutants (As, Cd, Cu, Mo, Ni, Pb, and Zn) in the studied sediment. Based on batch tests, hematite was used at one application rate equal to 5 % to conduct column experiments. Column tests confirmed that hematite was able to decrease metal concentrations in leachates from stabilized sediment. The stabilization rates were particularly high for Cd (67 %), Mo (80 %), and Pb (90 %). The Microtox solid phase test showed that hematite could decrease significantly the toxicity of stabilized sediment. Based on batch and column experiments, it emerged that hematite could be a suitable adsorbent to stabilize metals in dredged marine sediment. PMID:23370851

  14. Cable Bacteria in Freshwater Sediments.

    Science.gov (United States)

    Risgaard-Petersen, Nils; Kristiansen, Michael; Frederiksen, Rasmus B; Dittmer, Anders Lindequist; Bjerg, Jesper Tataru; Trojan, Daniela; Schreiber, Lars; Damgaard, Lars Riis; Schramm, Andreas; Nielsen, Lars Peter

    2015-09-01

    In marine sediments cathodic oxygen reduction at the sediment surface can be coupled to anodic sulfide oxidation in deeper anoxic layers through electrical currents mediated by filamentous, multicellular bacteria of the Desulfobulbaceae family, the so-called cable bacteria. Until now, cable bacteria have only been reported from marine environments. In this study, we demonstrate that cable bacteria also occur in freshwater sediments. In a first step, homogenized sediment collected from the freshwater stream Giber Å, Denmark, was incubated in the laboratory. After 2 weeks, pH signatures and electric fields indicated electron transfer between vertically separated anodic and cathodic half-reactions. Fluorescence in situ hybridization revealed the presence of Desulfobulbaceae filaments. In addition, in situ measurements of oxygen, pH, and electric potential distributions in the waterlogged banks of Giber Å demonstrated the presence of distant electric redox coupling in naturally occurring freshwater sediment. At the same site, filamentous Desulfobulbaceae with cable bacterium morphology were found to be present. Their 16S rRNA gene sequence placed them as a distinct sister group to the known marine cable bacteria, with the genus Desulfobulbus as the closest cultured lineage. The results of the present study indicate that electric currents mediated by cable bacteria could be important for the biogeochemistry in many more environments than anticipated thus far and suggest a common evolutionary origin of the cable phenotype within Desulfobulbaceae with subsequent diversification into a freshwater and a marine lineage. PMID:26116678

  15. Utilization of natural and supplemental biofuels for harvesting energy from marine sediments

    Science.gov (United States)

    Nielsen, Mark E.

    A benthic microbial fuel cell (BMFC) is an electrochemical device that generates current from the redox gradient at the sediment-water interface. Early prototypes had anodes buried in anoxic sediments and cathodes in overlying water. The BMFCs described in this dissertation are based on a chamber design that enables the use of high surface-area fiber electrodes and facilitates enhanced mass transport to the anode. Results from Yaquina Bay, OR, show that mass transport resistance accounted for at least 93% of the total internal resistance for a particular BMFC configuration. Power output was increased 18-fold by mechanically induced fluid transport through the anode chamber. At a cold seep in Monterey Canyon, CA, naturally driven advection resulted in a five-fold increase in power from a BMFC with low-pressure check valves relative to an identical BMFC with high-pressure check valves. Enhanced transport coincided with a change in the microbial community on the anode from one dominated by epsilonproteobacteria to one with relatively even representation from deltaproteobacteria, epsilonproteobacteria, firmicutes and flavobacterium/cytophaga/bacterioides. Laboratory experiments investigated the effect of adding supplemental carbon sources to anode chambers. Repeated lactate injections appeared to stimulate sulfate reduction resulting in short term power gains but did not apparently shift the process responsible for baseline current. When a specific inhibitor of sulfate reduction was added, lactate-supplemented and unsupplemented BMFCs performed similarly. BMFCs have been proposed as power sources for monitoring systems in remote locations. Practical implementation of this technology is governed by three conditions: (1) low-voltage current must be stepped up to meet the requirements of off-the-shelf electronic devices, (2) modest power production and variable power demands require integrated energy storage, and (3) BMFCs should be operated at the most efficient

  16. Certification of Trace Element Mass Fractions in IAEA-458 Marine Sediment Sample

    International Nuclear Information System (INIS)

    The primary goal of the IAEA Environment Laboratories (NAEL) is to help Member States understand, monitor and protect the marine environment. The major impact exerted by large coastal cities on marine ecosystems is therefore of great concern to the IAEA and its Environment Laboratories. Given that marine pollution assessments of such impacts depend on accurate knowledge of contaminant concentrations in various environmental compartments, the NAEL has assisted national laboratories and regional laboratory networks through its Reference Products for Environment and Trade programme since the early 1970s. Quality assurance (QA), quality control (QC) and associated good laboratory practice are essential components of all marine environmental monitoring studies. QC procedures are commonly based on the analysis of certified reference materials and reference samples in order to validate analytical methods used in monitoring studies and to assess reliability and comparability of measurement data. QA can be realized by participation in externally organized laboratory performance studies, also known as interlaboratory comparisons, which compare and evaluate the analytical performance and measurement capabilities of participating laboratories. Data that are not based on adequate QA/QC can be erroneous, and their misuse can lead to incorrect environmental management decisions. This report describes the sample preparation methodology, material homogeneity and stability study, selection of laboratories, evaluation of results from the certification campaign and assignment of property values and their associated uncertainty. As a result, reference values for mass fractions and associated expanded uncertainty for 16 trace elements (Al, As, Cd, Cr, Co, Cu, Fe, Hg, Li, Mn, Ni, Pb, Sr, Sn, V and Zn) in marine sediment were established

  17. Use of polyoxyethylene-6-lauryl ether and microwave-assisted extraction for the determination of chlorophenols in marine sediments

    Energy Technology Data Exchange (ETDEWEB)

    Santana, Cristina Mahugo; Ferrera, Zoraida Sosa; Rodriguez, Jose J. Santana

    2004-10-25

    Microwave-assisted micellar extraction was optimised and applied to the extraction, prior to analysis by liquid chromatography with diode array spectrophotometric detection, of chlorophenols in marine sediment samples. This study was carried out using a non-ionic surfactant polyoxyethylene-6-lauryl ether as extractant. Parameters studied included surfactant concentration, pH of the solution, extraction time and power. Once the method was optimised, it was applied to different spiked marine sediments from coasts of the Canary Islands (Spain). The results obtained indicate that irradiation of 500 W for 2 min achieved the best extraction efficiency (100% recovery) and standard deviation values <10%. Detection limits were obtained in the range 1.2-12.7 {mu}g g{sup -1} for the chlorophenols studied. The proposed method provides a simple, fast and organic solvent-free procedure to analyse for chlorophenols in marine sediment samples.

  18. Distribution of uranium in marine sediments; Distribucion de uranio en sedimentos marinos

    Energy Technology Data Exchange (ETDEWEB)

    Ordonez R, E.; Ramirez T, J.J.; Lopez M, J.; Aspiazu, J. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico); Ruiz F, A.C. [U. Academica Mazatlan, ICML, UNAM (Mexico); Valero C, N. [CONALEP, 52000 Lerma, Estado de Mexico (Mexico)

    2008-07-01

    The marine sediments obtained by means of a sampling nucleus in the Gulf of Tehuantepec, Mexico, they have been object of crystallographic and morphological characterization. The PIXE analysis of some samples in study is shown. The normal methodology to carry out the alpha spectroscopy indicates that the sample should be dissolved, but due to the nature of the marine sediments, it thinks about the necessity to make a fractional separation of the sample components. In each stratum of the profile it separates the organic part and the mineral to recover the uranium. It was observed that in the organic phase, the uranium is in two oxidation states (IV and Vl), being necessary the radiochemical separation with a liquid/liquid column chromatographic that uses the di-2-ethyl hexyl phosphoric acid as stationary phase. The uranium compounds extracts are electrodeposited in fine layers on stainless steel disks to carry out the analysis by alpha spectroscopy. The spectroscopic analysis of the uranium indicates us that for each stratum one has a difference marked in the quotient of activities of {sup 234}U/{sup 238}U that depends on the nature of the studied fraction. These results give us a clear idea about how it is presented the effect of the uranium migration and other radioelements in the biosphere, with what we can determine which are the conditions in that these have their maximum mobility and to know their diffusion patterns in the different media studied. (Author)

  19. Determination of naturally occurring uranium concentrations in seawater, sediment, and marine organisms in Japanese estuarine areas

    International Nuclear Information System (INIS)

    For safety assessments of geological repositories of nuclear waste, understanding of uranium (U) fate in estuarine areas is important because U chemical behavior in the areas is expected to be complex. Environmental transfer parameters such as sediment-water distribution coefficients (Kd) and concentration ratios (CRs) for marine organisms are useful in mathematical models for the assessment. However, due to its low concentration in estuarine water, Kd and CF data for U are scarce. Thus we studied a rapid method for separation and concentration of U from estuarine water samples using NOBIAS-CHELATE PA1 resin columns followed by inductively coupled plasma mass spectrometry (ICP-MS) for U measurement. Chemical recovery was about 100% at pH of 5.7 ± 0.1 from the water samples and alkali and alkaline earth metals were removed. The method was used to measure U concentrations in estuarine water samples collected at eight Japanese estuarine areas; they ranged from 0.1 to 3.8 μg L-1. We also measured U concentrations in sediment and marine organism samples by ICP-MS after acid digestion. Using these values, we observed K d (range: 39-284 L kg-1) and CRs (0.86-52 L kg-1 for macroalgae, 0.087-15 L kg-1 for crustaceans, and 0.52-93 L kg-1 for molluscs). (author)

  20. Measurement of artificial radionuclides in some marine plants and sediments from the Sudanese Red sea coast

    International Nuclear Information System (INIS)

    The activity concentration of fallout radionuclides v.z., 238Pu, 239+240Pu, 241Am and 137Cs has been measured in some species of multicellular marine algae, sea grass and surface sediments collected from the fringing reef area adjacent to to port Sudan harbour. The measurements were carried using alpha-particle spectrometry and a high resolution gamma spectrometry. In the sediments analyzed, the activity concentration averaged 2.65 (238Pu), 47.96 (239+240Pu), 19.1 (241Am ), and 272.6 (137Cs) MBq/kg dry weight. Activity concentration ratios fall within the range of 0.03-0.15 (238Pu:239+240Pu), 0.09-0.39 (239+240Pu:137Cs ), and 0.29-0.65 (241Am:239+240Pu). These values are typical of those reported in the literature from the regions not affected directly by nuclear accidents or nuclear reprocessing plant discharges and can thus be attributed to global fallout. Marine algae shoed high levels of 137Cs ; 774 mBq/kg (brown algae), 771 (red algae) and 369 (green algae), which seem to confirm that algae are responsive to the soluble phase of constituents in the ambient medium more that the elements associated to particle matter. (Author)

  1. Measurement of Artificial Radionuclides in Some Marine Plants and Sediments from the Sudanese Red Sea Coast

    International Nuclear Information System (INIS)

    The activity concentration of fallout radionuclides v.z.,238Pu, 239+240Pu, 241Am and 137Cs has been measured in some species of multicellular marine algae, sea grass and surface sediments collected from the fringing reef area adjacent to PortSudan harbour. The measurements were carried out using alpha-particle spectrometry and a high-resolution gamma spectrometry. In the sediments analyzed, the activity concentration averaged 2.65 (238Pu),47,96(239+240Pu), 19.1 (241Am), and 272.6 (137Cs) mBq/KXg dry weight. Activity concentration ratios fall within the range of 0.03-0.15 (238Pu: 239+240Pu), 0.09-0.39 (239+240Pu: 137Cs), and 0.29-0.65 (241Am:239+240Pu). These values are typical of those reported in the literature from the regions not affected directly by nuclear accidents or nuclear reprocessing plant discharges and can thus be attributed to global fallout. Marine algae showed high levels of 137Cs: 774 mBq/KXg (brown algae), 771 (red algae) and 369 (green algae), which seem to confirm that algae are responsive to the soluble phase of constituents in the ambient medium more than the elements associated to particulate matter

  2. Formation of pristane from α-tocopherol under simulated anoxic sedimentary conditions: A combination of biotic and abiotic degradative processes

    Science.gov (United States)

    Rontani, Jean-François; Nassiry, Mina; Michotey, Valérie; Guasco, Sophie; Bonin, Patricia

    2010-01-01

    Incubation of intact and oxidized α-tocopherol (vitamin E) in anaerobic sediment slurries allowed us to demonstrate that, as previously suggested by Goossens et al. (1984), the degradation of α-tocopherol in anoxic sediments results in the formation of pristane. The conversion of α-tocopherol to this isoprenoid alkane involves a combination of biotic and abiotic degradative processes, i.e. the anaerobic biodegradation (which seems to be mainly induced by denitrifying bacteria) of trimeric structures resulting from the abiotic oxidation of α-tocopherol. On the basis of the results obtained, it is proposed that in the marine environment most of the α-tocopherol present in phytoplanktonic cells should be quickly degraded within the water column and the oxic zone of sediments by way of aerobic biodegradation, photo- and autoxidation processes. Abiotic transformation of this compound mainly results in the production of trimeric oxidation products, sufficiently stable to be incorporated into anoxic sediments and whose subsequent anaerobic bacterial degradation affords pristane. These results confirm that the ratio pristane to phytane cannot be used as an indicator of the oxicity of the environment of deposition; in contrast, they support the use of PFI (Pristane Formation Index) as a proxy for the state of diagenesis of sedimentary organic matter.

  3. Morphology and Sediment Transport Dynamics of a Trough-Blowout Dune, Bodega Marine Reserve, Northern California

    Science.gov (United States)

    Jorgenson, D.; Dunleavy, C. J.; Smith, M. E.

    2014-12-01

    Blowout dunes are a primary mechanism for transporting sand within vegetated coastal dune systems. Understanding the fine-scale variation in sediment transport within these systems is critical to predicting their formation and migration. Previous investigations of a coastal dune system located at the Bodega Marine Reserve, on the Sonoma Coast of Northern California have indicated that aeolian sand flux in unvegetated sand is ~450x greater than in vegetated areas. To better understand sand flux and its relationship with wind speed, direction and precipitation, we deployed an array of 12 sand traps within a single blowout area adjacent to the BOON marine climatology station. The blowout is trough- shaped, approximately 50 meters long and 15 meters wide. Its main 'fairway' is 5-10 meters below the surrounding beach grass (Ammophila)-covered land surface. Surface sediment within the blowout is fine-grained to granule-sized lithic to sub-lithic sand, and is coarsest in the center. Dune sediment in the Bodega Marine Reserve has been transported by aeolian processes from Salmon Creek Beach to the NW. Within the blowout, typical bedforms include 15-25 cm-wavelength, ~10 cm high sinuous to lingoid ripples arranged perpendicularly to the dominant wind direction (~280 degrees). An 8-10 meter-high mound at the downwind end has accumulated due to the trapping of sand flux by vegetation. Sediment flux across the studied blowout was sampled monthly over a 10-month period of 2013-2014. Sand traps were constructed using modified PVC cylinders, and are 0.5 meter high and 0.3 meter in diameter, with a 0.74-micron mesh screen. Based on measured sand flux, the sites can be categorized into three groups-axial, medial, and peripheral. Rates increase downwind within the blowout. Inter-site sand flux variability within unvegetated locations of the blowout is greater than two orders of magnitude. Axial sites, which experience the greatest sand flux, occur on the edge of the blowout adjacent

  4. Analysis and evaluation of uranium and thorium marine sediments around abu-dhabi island of UAE

    International Nuclear Information System (INIS)

    Both uranium and thorium are source nuclear materials of indirect uses. They are of natural and anthropogenic origin. Elevated levels of uranium and thorium were found in several marine sediments as a result of nuclear activity releases. Currently, marine environmental samples can be used to trace origin and potential contamination of declared or undeclared nuclear activities. In this work, marine bottom sediment samples were collected from the Arabian Gulf at shores of Abu Dhabi Island. The samples were analyzed for uranium and thorium and two different techniques were employed in the analysis (one is non-destructive and the other is destructive). The first was gamma spectrometry (GS) based on hyper pure germanium detector of 40% efficiency; and the second was inductively coupled plasma - mass spectrometry (ICP-MS). The uranium and thorium concentrations in the investigated samples were found to be in the ranges 1.19 - 6.51 ppm and 0.48 - 13.5 ppm, respectively using GS and to be in the ranges 1.13 - 6.79 ppm and 0.37 - 14.63 ppm using ICP-MS. The calculated Th/U ratio based on GS and ICP-MS analysis was found to be from 0.23 to 8.04 and from 0.12 to 8.76, respectively. The calculated Th/U ratios reveal that two of the studied sites are slightly enriched with thorium in respect to uranium. The results of the two techniques are compared and evaluated and the levels of uranium and thorium in the studied samples are discussed

  5. Early Cretaceous marine sediments of the Lower Saxony Basin. The Gildehaus Sandstone

    Energy Technology Data Exchange (ETDEWEB)

    Dellepiane, S.; Weiel, D. [Wintershall Holding GmbH, Barnstorf (Germany); Gerwert, D.; Mutterlose, J. [Bochum Univ. (Germany). Inst. fuer Geologie, Mineralogie und Geophysik

    2013-08-01

    During the Early Cretaceous (Berriasian - Aptian) the Lower Saxony Basin (LSB) formed the southernmost extension of the North Sea Basin. Sedimentation patterns of the LSB were controlled by divergent dextral shear movement causing differential subsidence related to early rifting in the North Sea. Up to 2000m of fine grained mudstones accumulated in the basin centre, while marginal marine, coarser grained siliciclastics were deposited along the western and southern margins of the LSB. The western marginal facies, outcropping along the Dutch-German border, is characterised by shallow marine sandstones of Valanginian - Hauterivian age. These units, which are separated by clay rich intervals, include the Bentheim Sdst., the Dichotomites Sdst., the Grenz Sdst., the Noricum Sdst. and the Gildehaus Sdst. These sandstones form a series of overall backstepping units, controlled by a main transgressive trend. Economically important are the Bentheim Sdst. and the Gildehaus Sdst., with a long oil producing history. The Bentheim Sdst. (early Valanginian) has been interpreted as an overall retrograding unit related to an incised valley infill with material mainly coming from the South. Tidal processes dominated the deposition of the Bentheim Sdst. The origin and genesis of the Gildehaus Sdst. (mid Hauterivian) is, however, less well understood. Here we present data from two wells drilled to the Gildehaus Sdst. (Emlichheim oil field) which provide evidence for a two fold subdivision of the unit. A well sorted massive quartz sandstone is followed by an interval composed of reworked coarse clastics of massflow origin. Micropalaeontological evidence suggests a fully marine, hemi-pelagic origin of the mud dominated matrix throughout the Gildehaus Sdst. These findings indicate a depositional environment quite different from that of the Bentheim Sdst. Short termed pulses of substantial input of clastic material from two different sources in the West to Southwest punctuated the overall

  6. Search for isotopic signatures of a supernova explosion close to the solar system in marine sediments

    International Nuclear Information System (INIS)

    The recent observation of a 60Fe peak in a deep-sea ferro-manganese crust has been interpreted as due to a supernova explosion relatively close to the solar system 2.8 ± 0.4 Myr ago. To confirm this interpretation with better time-resolved measurements, and the simultaneous access, on the same sample, to other isotopes and geochemical phases, marine sediments seem to be a tool of choice. The objective of this work was to search for isotopic anomalies which would be characteristic for residues of this supernova. More specifically, 129I, 60Fe, and 26Al have been investigated, being measured by Accelerator Mass Spectrometry (AMS). Quantifying these nuclides' fluxes would help constrain stellar nucleosynthesis models. These residues are isotopes initially produced during hydrostatic and/or explosive nucleosynthesis. The physical conditions during the explosion (temperature, neutron density) are such that supernovae are thought to be good candidates for the astrophysical site of the r-process. The 129I study showed that measurement of pre-anthropogenic 129I/127I ratios need a very strict control of the various potential 129I sources, especially when working with small quantities (micrograms) of iodine. This study revealed that the expected pre-anthropogenic 129I/127I ratio for pre-nuclear samples in the marine environment shows a large discrepancy between theoretical calculations and experimental measurements. 60Fe and 26Al measurements allow us to conclude that, in the authigenic phase of the marine sediments, there is no 60Fe anomaly in the time interval defined by the signal found on the Fe-Mn crust (from 2.4 to 3.2 Myr), and no 26Al anomaly from 2.6 to 3.2 Myr. (author)

  7. Isoprenoid and branched GDGT-based proxies for surface sediments from marine, fjord and lake environments in Chile

    OpenAIRE

    J. Kaiser; Schouten, S.; Kilian, R.; H. W. Arz; F. Lamy; Sinninghe Damsté, J.S.

    2015-01-01

    Proxies based on glycerol dialkyl glycerol tetraether (GDGT) lipids from archaea [isoprenoid GDGTs] and bacteria [branched (br) GDGTs] in 33 surface sediments from marine, fjord and lake systems between 25°S and 50°S in Chile were analyzed. The regional TEXH86 calibration obtained from the marine and fjord sediments and mean annual surface temperature (T = 59.6 × TEXH86 + 33.0; r2 0.9; n = 23) is statistically identical to the global ocean calibration based on suspended particulate material i...

  8. Assessment of 210Po in agricultural soils and marine sediments of the Atlantic and Pacific oceans of Guatemala

    International Nuclear Information System (INIS)

    A radiochemical method consisting of 210Polonium extraction was made to measure radioactivity in samples of soil and marine sediments of Atlantic and Pacific Ocean. The solution of polonium it was treated to obtain the deposition of the metal over a zinc disc and was measured by alpha espectrometry system based on Planar Ion Planted Silice (PIPS) system. The concern about cultivated soils its consuption products from sea and soil come from these sources. The results shows that activity of 210Polonium in agricultural soils and marine sediments are below of ALI recommended by international standards

  9. Fulvibacter tottoriensis gen. nov., sp. nov., a member of the family Flavobacteriaceae isolated from marine sediment.

    Science.gov (United States)

    Khan, Shams Tabrez; Nakagawa, Yasuyoshi; Harayama, Shigeaki

    2008-07-01

    A novel bacterium, MTT-39(T), was isolated from a sample of marine sediment collected at Tottori on the coast of the Sea of Japan. Cells were Gram-negative, rod-shaped and non-motile. The bacterium formed yellowish brown colonies on marine agar 2216. Although the 16S rRNA gene sequence of strain MTT-39(T) classified this strain as a member of the family Flavobacteriaceae, the maximum sequence similarity obtained was only 91.5 % (with Kordia algicida OT-1(T)). In the maximum-likelihood tree based on 16S rRNA gene sequences, the novel bacterium clustered with the type strains of Kordia algicida, Lutibacter litoralis, Tenacibaculum maritimum and Polaribacter filamentus. The novel strain exhibited the following characteristics: the predominant fatty acids in cells grown on artificial seawater-based tryptic soya agar were iso-C(15 : 1), iso-C(15 : 0) and iso-C(15 : 0) 3-OH, the major respiratory quinone was MK-6 and the DNA G+C content was 35 mol%. On the basis of its distinct phenotypic traits and the phylogenetic distance between this marine isolate and other recognized taxa, strain MTT-39(T) represents a novel genus and species of the family Flavobacteriaceae, for which the name Fulvibacter tottoriensis gen. nov., sp. nov. is proposed. The type strain of the type species is MTT-39(T) (=NBRC 102624(T)=KCTC 22214(T)=CGMCC 1.7058(T)). PMID:18599714

  10. Study on Stability of Sequential Extraction Method for Heavy Metal Speciations in Anoxic Sediments%缺氧沉积物中重金属形态连续萃取方法的稳定性研究

    Institute of Scientific and Technical Information of China (English)

    王畅; 夏冰; 王冠华; 宋玉梅; 吴凌涛; 郭鹏然

    2012-01-01

    Effects of the variations of pH value, temperature and colloidal particles in extractant solutions on heavy metals speciations were investigated by the sequential extraction procedure ( SEP) used in anoxic sediments at mariculture zone. The results showed that a slight increasement of pH values of extractant solutions lead to the decrease of concentrations of Cd and Zn in Stepl of SEP for acid soluble speciations, However, the obvious variations of pH values of extractant solutions had no significant influence on heavy metals speciations in Step2 for reducible fraction and Step3 for organic matter bound fraction ( except Pb) , respectively. The temperature of extractant solutions were slightly increased in Stepl and Step2 and decreased in Step3 due to the different reaction thermodynamics in extraction steps of SEP, and the variations of temperature( <2. 5) had little effects on the concentrations of heavy metals speciations. Due to adsorption, the formation of colloid in Stepl, Step2 and Step4 resulted in the decrease of Cd, Zn and Cu concentrations, respectively. However, the formation of colloid was controlled by extractant in Step3. Therefore, controlling pH and colloid in extractant solutions were available to improve the stability and accuracy of extraction results when SEP was applied to evaluate heavy metals speciations in anoxic sediments.%考察了海水养殖区域缺氧沉积物中重金属形态连续萃取法萃取过程中溶液pH值、温度变化和胶体形成对形态分离结果的影响.结果表明,连续萃取法Step1萃取酸溶态时,萃取液pH值的轻微升高使Pb和Zn的萃取结果明显降低;Step2萃取还原态时,萃取液pH值明显升高对重金属的萃取结果影响很小;Step3萃取有机质结合态时,萃取液pH值的降低对重金属萃取结果影响较小(除Pb外).由于连续萃取法中各步萃取反应的热力学过程不同,Step1和Step2萃取后溶液温度轻微升高而在Step3中溶液温度稍

  11. Speedy instrumental decoding of the marine-sediment as an indicator of environment pollution (abstract)

    International Nuclear Information System (INIS)

    Pedogenesis and drainage determine quantity and quality of material to be transported from the terrestrial ecosystem to aquatic ecosystem. Thus identification of controlling factors for the accumulation of certain elemental burden is important while, studying recent anthropogenic sources on soil and ground water elemental geochemistry. The continuous supply of organic and inorganic material in aquatic system such as lake, rivers and estuaries renders the sediment-water interface by marked chemical changes, resulting in steep gradients in physical, chemical and biological properties. Biogenic, authigenic and mineral particle which settle at the sediment surface accumulate to relatively high concentration and compared to their time in water column, have an appreciably long time in which to react mutually henceforth to the surrounding interacting forces. The particle flux in the ocean response to wind speed, aerosol deposition, nutrient level, carbon dioxide levels in the mixed layer, availability of the trace element such as Fe and volcanic emissions. Biochemical processes taking place in the deep ocean are coupled to the atmospheric processes via the particle flux in the ocean. As the oceanic flux, responds to the climatic and environmental forces, it has also a potential to detect and monitor, thus permitting the reconstruction of the global changes in the past. Thus, in spite of the fact that are distinct correlation between concentration and the distance of the sampling point from potential source such as industry, highway or municipal can not be established sediments from sea, lake, estuaries or river could be valuable tool to show spatial and temporal trends of metal contamination. Studies have been undertaken to construct a comprehensive scenario of environmental impact from marine pollution. Hence present work attempts to evaluate enrichment of various metals and cations in marine sediments from Japanese and Pakistan coastal areas. Concentration of Cr, Cu, Cd

  12. Nitrogen Cycling and Community Structure of Proteobacterial β-Subgroup Ammonia-Oxidizing Bacteria within Polluted Marine Fish Farm Sediments

    OpenAIRE

    McCaig, Allison E.; Phillips, Carol J.; Stephen, John R.; Kowalchuk, George A.; Harvey, S. Martyn; Herbert, Rodney A.; Embley, T. Martin; Prosser, James I

    1999-01-01

    A multidisciplinary approach was used to study the effects of pollution from a marine fish farm on nitrification rates and on the community structure of ammonia-oxidizing bacteria in the underlying sediment. Organic content, ammonium concentrations, nitrification rates, and ammonia oxidizer most-probable-number counts were determined in samples of sediment collected from beneath a fish cage and on a transect at 20 and 40 m from the cage. The data suggest that nitrogen cycling was significantl...

  13. How magnetics and granulometry of continental margin sediments reflect terrestrial and marine environments of South America and West Africa

    OpenAIRE

    Razik, Sebastian

    2014-01-01

    Continental margins are supplied by terrigenous clastic, as well as by biogenic marine sediments and, thus, act as natural archives for various environmental conditions. This thesis delineates sediment-distribution patterns off SE South America (20-55 deg. S) and NW Africa (14-17 deg. N) mainly based on rock-magnetic properties supplemented by clastic grain-size distributions, major-element concentrations, planktic and benthic foraminiferal assemblages, as well as stable-isotope signatures ob...

  14. The in vitro influence of the burrowing polychaete Nereis diversicolor on the fate of petroleum hydrocarbons in marine sediments

    OpenAIRE

    Gilbert, Franck; Rivet, Lucien; Bertrand, Jean-Claude

    1994-01-01

    International audience The in vitro fate of the saturated hydrocarbon fraction (SF) of Arabian Light crude oil has been studied in PVC cores filled with a coastal marine sediment defaunated by sieving. Experiments were conducted in absence or presence of polychaetes Nereis diversicolor. The luminophore tracer technique was used to quantify the mixing of sediment by worms. Presence of crude oil reduced the building of burrows by polychaetes. This work demonstrates the ability of infaunal or...

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

    OpenAIRE

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

    2012-01-01

    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 p...

  16. Chemical composition of marine sediments in the Pacific Ocean from Sinaloa to Jalisco, Mexico

    International Nuclear Information System (INIS)

    Marine sediments from Mexico's West coast in the Pacific Ocean from Sinaloa to Jalisco were analyzed by energy-dispersive X-ray fluorescence technique. Ten sediment samples were collected in May, 2010 between 55.5 and 1264 m water depth with a Reinneck type box nucleate sampler. Sediments were dried and fractioned by granulometry. Their physical and chemical properties were determined in laboratory by standard methods, pH, and conductivity. Concentration and distribution of K, Ca, Ti Mn, Fe, Cu, Zn, Ga, Pb, Br and Sr were analyzed. In order to determine the status of the elements, enrichment factors were calculated. Total, organic carbon and CaCO3 were also determined. Scanning electron microscopy and X-ray diffraction show predominant groups of compounds. As quality-control method, Certified Reference Material was both processed and analyzed at even conditions. Enrichment factors for K, Ca, Ti, Mn Fe, Cu, Zn, Ga, Ni, and Sr show they are conservative elements having concentrations in the range of unpolluted sites giving a base data line for the sampling zone In spite of moderately enrichment factors -1) and enrichment factor show the influence of anthropogenic sources with values between lowest effect level and a third part of 250 μg g-1value, which is considered to have severe effect levels for aquatic life. (author)

  17. Rare earth elements in core marine sediments of coastal East Malaysia by instrumental neutron activation analysis.

    Science.gov (United States)

    Ashraf, Ahmadreza; Saion, Elias; Gharibshahi, Elham; Kamari, Halimah Mohamed; Kong, Yap Chee; Hamzah, Mohd Suhaimi; Elias, Md Suhaimi

    2016-01-01

    A study was carried out on the concentration of REEs (Dy, Sm, Eu,Yb, Lu, La and Ce) that are present in the core marine sediments of East Malaysia from three locations at South China Sea and one location each at Sulu Sea and Sulawesi Sea. The sediment samples were collected at a depth of between 49 and 109 m, dried, and crushed to powdery form. The entire core sediments prepared for Instrumental Neutron Activation Analysis (INAA) were weighted approximately 0.0500 g to 0.1000 g for short irradiation and 0.1500 g to 0.2000 g for long irradiation. The samples were irradiated with a thermal neutron flux of 4.0×10(12) cm(-2) s(-1) in a TRIGA Mark II research reactor operated at 750 kW. Blank samples and standard reference materials SL-1 were also irradiated for calibration and quality control purposes. It was found that the concentration of REEs varies in the range from 0.11 to 36.84 mg/kg. The chondrite-normalized REEs for different stations suggest that all the REEs are from similar origins. There was no significant REEs contamination as the enrichment factors normalized for Fe fall in the range of 0.42-2.82. PMID:26405840

  18. Application of silicone rubber passive samplers to investigate the bioaccumulation of PAHs by Nereis virens from marine sediments

    International Nuclear Information System (INIS)

    The availability of polycyclic aromatic hydrocarbons (PAHs) from marine sediments to the ragworm (Nereis virens) was studied. Concentrations of PAHs in pore waters were determined using silicone rubber passive samplers. Calculated bioconcentration factors confirmed that partitioning of PAHs between the lipid phase of the polychaetes and pore water is a passive process. Low biota-sediment accumulation factors (BSAF) calculated using total sediment concentration suggested a fraction of the total PAH burden in the sediment may be strongly sorbed to organic carbon and not available to the polychaete. Organic carbon normalised concentrations of the potentially exchangeable fractions of contaminants and freely dissolved concentrations (measured using silicone rubber samplers) provide a better description of the observed bioaccumulation by the ragworms. These data indicate that the concept of availability should be included in environmental risk assessments based upon equilibrium partitioning models, and that silicone rubber samplers can provide the necessary information for these models. - Highlights: → PAH availability from marine sediments to Nereis virens. → Utilised silicone rubber samplers to measure PAH freely dissolved concentrations. → Fraction of PAH burden not available for uptake by polychaete. → Concept of availability should be incorporated in equilibrium partitioning models. - Silicone rubber samplers provide data on availability of PAHs from marine sediments which improves determination of bioaccumulation potential in Nereis virens.

  19. Application of silicone rubber passive samplers to investigate the bioaccumulation of PAHs by Nereis virens from marine sediments

    Energy Technology Data Exchange (ETDEWEB)

    Yates, Kyari, E-mail: k.yates@rgu.ac.uk [School of Pharmacy and Life Sciences, Robert Gordon University, Aberdeen, AB25 1HG (United Kingdom); Pollard, Pat [School of Pharmacy and Life Sciences, Robert Gordon University, Aberdeen, AB25 1HG (United Kingdom); Davies, Ian M.; Webster, Lynda [Marine Scotland Science Marine Laboratory, 375 Victoria Road, Aberdeen, AB11 9DB (United Kingdom); Moffat, Colin F. [Marine Scotland Science Marine Laboratory, 375 Victoria Road, Aberdeen, AB11 9DB (United Kingdom); School of Pharmacy and Life Sciences, Robert Gordon University, Aberdeen, AB25 1HG (United Kingdom)

    2011-12-15

    The availability of polycyclic aromatic hydrocarbons (PAHs) from marine sediments to the ragworm (Nereis virens) was studied. Concentrations of PAHs in pore waters were determined using silicone rubber passive samplers. Calculated bioconcentration factors confirmed that partitioning of PAHs between the lipid phase of the polychaetes and pore water is a passive process. Low biota-sediment accumulation factors (BSAF) calculated using total sediment concentration suggested a fraction of the total PAH burden in the sediment may be strongly sorbed to organic carbon and not available to the polychaete. Organic carbon normalised concentrations of the potentially exchangeable fractions of contaminants and freely dissolved concentrations (measured using silicone rubber samplers) provide a better description of the observed bioaccumulation by the ragworms. These data indicate that the concept of availability should be included in environmental risk assessments based upon equilibrium partitioning models, and that silicone rubber samplers can provide the necessary information for these models. - Highlights: > PAH availability from marine sediments to Nereis virens. > Utilised silicone rubber samplers to measure PAH freely dissolved concentrations. > Fraction of PAH burden not available for uptake by polychaete. > Concept of availability should be incorporated in equilibrium partitioning models. - Silicone rubber samplers provide data on availability of PAHs from marine sediments which improves determination of bioaccumulation potential in Nereis virens.

  20. New procedure for recovering extra- and intracellular DNA from marine sediment samples

    Science.gov (United States)

    Alawi, M.; Kallmeyer, J.

    2012-12-01

    opposing composition were analyzed. Sediment from the South Pacific Gyre, the most oligotrophic oceanic region on earth and organic-rich Baltic Sea sediment (Northern Germany) were processed. Using this new procedure high purity genomic iDNA and eDNA with a molecular size range between 20 bp and 50k bp can be simultaneously recovered even from very oligotrophic sediment with very low cell abundances. The main fraction of recovered eDNA was suitable for downstream applications like PCR and had a molecular size that indicates minimal shearing. Despite about two decades of research many questions about deep subsurface life remain unanswered. The fact that microbes can be found even in deep oligotrophic marine sediment raises the fundamental questions of the types and availability of substrates and their biogeochemical cycling. This is the first study that provides evidence that eDNA is an important potential substrate for microorganisms in the deep biosphere. Also, our results show a link between cell counts and eDNA content, indicating that the eDNA pool in the investigated sediment consist mainly of microbial DNA. Comparative sequence analysis of extracted iDNA and eDNA will provide deeper insights into the origin and turnover of eDNA and the apparent microbial community composition in the deep biosphere.

  1. Effects of pollution on the geochemical properties of marine sediments across the fringing reef of Aqaba, Red Sea.

    Science.gov (United States)

    Al-Rousan, Saber; Al-Taani, Ahmed A; Rashdan, Maen

    2016-09-15

    The Gulf of Aqaba is of significant strategic and economic value to all gulf-bordering states, particularly to Jordan, where it provides Jordan with its only marine outlet. The Gulf is subject to a variety of impacts posing imminent ecological risk to its unique marine ecosystem. We attempted to investigate the status of metal pollution in the coastal sediments of the Jordanian Gulf of Aqaba. The distribution of Cd, Cr, Zn, Cu, Pb, Al, Fe, and Mn concentrations were determined in trapped and bottom-surface sediments at three selected sites at different depths. In addition, monthly sedimentation rates at varying water depths were also estimated at each sampling site using sediment traps. The high concentrations of Cd, Cr, Zn were recorded at the Phosphate Loading Birth (PLB) site followed by the Industrial Complex (IC) site indicating their dominant anthropogenic source (i.e., the contribution of industrial activities). However, Fe, Al, and Mn contents were related to inputs from the terrigenous (crustal) origin. Except for Al, Fe and Mn at the PLB site, the concentrations of metals exhibited a decreasing trend with increasing water depth (distance from the shoreline). The PLB site also showed the highest sedimentation rate which decreased with increasing water depth. The Enrichment factors (EFs) showed that Cd was the most enriched element in the sediment (indicating that Cd pollution is widespread), whereas the least enriched metal in sediments was Cu. EF values suggested that the coastal area is impacted by a combination of human and natural sources of metals, where the anthropogenic sources are intense in the PLB site (north of Gulf of Aqaba). The MSS area is potentially the least polluted, consistent with being a marine reserve. The IC sediments have been found to be impacted by human activities but less intensely compared to the PLB area. These results suggested that there are two sources of metals in sediments; the primary source is likely closer to PLB

  2. [Guest article:] Marine sediments as a high-resolution archive of climate variability

    International Nuclear Information System (INIS)

    The 'debate' in the global climate debate arises partly because of uncertainty about natural variability in global climate. The instrumental record (daily temperature, pressure and rainfall measurements, supplemented more recently by satellite imagery, upper atmospheric monitors and marine buoys) only extends back to the middle of the nineteenth century, and the perennial question is how certain can we be that this record contains all possible or relevant variation? To look further back in time, researchers in the discipline of palaeoclimatology study records (proxies) of climate change preserved in rock, sediment or biological materials. A well-known example of a proxy in the natural environment would be the changes in the thickness or density of tree rings in response to changes in precipitation. Most individual proxies have ambiguous interpretations with respect to climate and it is necessary to investigate several from the one location (called a multiproxy study) in order to unravel the complete story. To construct a global picture of prehistoric climate change, scientists must study proxies from a range of surface habitats, from marine to terrestrial and tropical to polar, just as it is necessary to have a number of weather stations to build up a picture of regional or national rainfall distribution. Six criteria of an ideal palaeoclimate-record: 1. high resolution, preferably annual or seasonal, 2. responsive to small changes in climate variables, 3. closed system, 4. record a continuous time series, 5. globally distributed 6. be datable. The current suite of natural archives includes corals, ice cores, tree rings, varved sediments and speleothems, but none meet all of the ideal criteria. Therefore it is necessary to cross correlate both records and proxies, thereby increasing uncertainty in interpretation. Corals contain seasonal or sub-seasonal growth rings that record variables such as sea surface temperature and salinity, but are generally short in their

  3. Determination of typical lipophilic marine toxins in marine sediments from three coastal bays of China using liquid chromatography-tandem mass spectrometry after accelerated solvent extraction.

    Science.gov (United States)

    Wang, Yanlong; Chen, Junhui; Li, Zhaoyong; Wang, Shuai; Shi, Qian; Cao, Wei; Zheng, Xiaoling; Sun, Chengjun; Wang, Xiaoru; Zheng, Li

    2015-12-30

    A method based on sample preparation by accelerated solvent extraction and analysis by liquid chromatography-tandem mass spectrometry was validated and used for determination of seven typical lipophilic marine toxins (LMTs) in marine sediment samples collected from three typical coastal bays in China. Satisfactory specificity, reproducibility (RSDs ≤ 14.76%), stability (RSDs ≤ 17.37%), recovery (78.0%-109.0%), and detection limit (3.440 pg/g-61.85 pg/g) of the developed method were achieved. The results obtained from the analysis of samples from Hangzhou Bay revealed okadaic acid as the predominant LMT with concentrations ranging from 186.0 to 280.7 pg/g. Pecenotoxin-2 was quantified in sediment samples from Laizhou Bay at the concentrations from 256.4 to 944.9 pg/g. These results suggested that the proposed method was reliable for determining the typical LMTs in marine sediments and that the sediments obtained from Hangzhou Bay, Laizhou Bay and Jiaozhou Bay were all contaminated by certain amounts of LMTs. PMID:26507511

  4. 10Be dating of marine core sediment from Central Western Bay of Bengal by using accelerator mass spectrometry

    International Nuclear Information System (INIS)

    A 4.12 m long marine sediment gravity core was collected during 157 cruise of ORV Sagar Kanya (October 2000) from the marginal coastal waters of central western Bay of Bengal. Sediment samples were taken for every 50cm interval; i.e 7 samples are studied for dating purpose. Rate of sedimentation and age of the core was determined with the cosmogenic radionuclide 10Be by using Accelerator Mass Spectrometry (AMS). 9Be was determined using ICPMS. The data is in good agreement with literature values. (author)

  5. Effects of oil dispersant and oil on sorption and desorption of phenanthrene with Gulf Coast marine sediments

    International Nuclear Information System (INIS)

    Effects of a model oil dispersant (Corexit EC9500A) on sorption/desorption of phenanthrene were investigated with two marine sediments. Kinetic data revealed that the presence of the dispersant at 18 mg/L enhanced phenanthrene uptake by up to 7%, whereas the same dispersant during desorption reduced phenanthrene desorption by up to 5%. Sorption isotherms confirmed that at dispersant concentrations of 18 and 180 mg/L, phenanthrene uptake progressively increased for both sediments. Furthermore, the presence of the dispersant during desorption induced remarkable sorption hysteresis. The effects were attributed to added phenanthrene affinity and capacity due to sorption of the dispersant on the sediments. Dual-mode models adequately simulated sorption isotherms and kinetic data in the presence of the dispersant. Water accommodated oil (WAO) and dispersant-enhanced WAO increased phenanthrene sorption by up to 22%. This information is important for understanding roles of oil dispersants on the distribution and transport of petroleum PAHs in seawater-sediments. Highlights: • Presence of oil dispersant enhances phenanthrene sorption in Gulf Coast sediments. • Oil dispersant present during desorption induces phenanthrene sorption hysteresis. • Dual-mode models adequately represent phenanthrene sorption isotherms and kinetics. • Dispersed oil substantially increases sediment sorption of phenanthrene. -- Oil dispersant and dispersed oil in seawater increase phenanthrene sorption capacity by marine sediments and induce remarkable sorption hysteresis

  6. Linking microbial community structure to biogeochemical function in coastal marine sediments: Stable isotope probing combined with magnetic bead capture

    NARCIS (Netherlands)

    T. Miyatake

    2011-01-01

    Microbial community structure and its biogeochemical functions in marine sediments can be successfully linked by using the improved Mag-SIP method in combination with other approaches. In this thesis, we were able to provide detailed information on the microorganisms responsible for the utilization

  7. Thiosulfate and Sulfite Distributions in Porewater of Marine-Sediments Related to Manganese, Iron, and Sulfur Geochemistry

    DEFF Research Database (Denmark)

    THAMDRUP, B.; FINSTER, K.; FOSSING, H.; HANSEN, JW; JØRGENSEN, BB

    1994-01-01

    Depth distributions of thiosulfate (S2O32-) and sulfite (SO32-) were measured in the porewaters of a Danish salt marsh and subtidal marine sediments by HPLC analysis after derivatization with DTNP [2,2'-dithiobis(5-nitropyridine)]. The distributions were compared to the redox zonation as indicate...

  8. Low-temperature partial magnetic self-reversal in marine sediments by magnetostatic interaction of titanomagnetite and titanohematite intergrowths

    NARCIS (Netherlands)

    Garming, J.F.L.; Von Dobeneck, T.; Franke, C.; Bleil, U.

    2007-01-01

    With various low-temperature experiments performed on magnetic mineral extracts of marine sedimentary deposits from the Argentine continental slope near the Rio de la Plata estuary, a so far unreported style of partial magnetic self-reversal has been detected. In these sediments the sulphate-methane

  9. Marine protected areas and resilience to sedimentation in the Solomon Islands

    Science.gov (United States)

    Halpern, B. S.; Selkoe, K. A.; White, C.; Albert, S.; Aswani, S.; Lauer, M.

    2013-03-01

    The ability of marine protected areas (MPAs) to provide protection from indirect stressors, via increased resilience afforded by decreased impact from direct stressors, remains an important and unresolved question about the role MPAs can play in broader conservation and resource management goals. Over a five-year period, we evaluated coral and fish community responses inside and outside three MPAs within the Roviana Lagoon system in Solomon Islands, where sedimentation pressure from upland logging is substantial. We found little evidence that MPAs decrease impact or improve conditions and instead found some potential declines in fish abundance. We also documented modest to high levels of poaching during this period. Where compliance with management is poor, and indirect stressors play a dominant role in determining ecosystem condition, as appears to be the case in Roviana Lagoon, MPAs may provide little management benefit.

  10. Feasibility studies for the treatment and reuse of contaminated marine sediments.

    Science.gov (United States)

    Bonomoa, L; Careghini, A; Dastoli, S; De Propris, L; Ferrari, G; Gabellini, M; Saponaro, S

    2009-07-01

    This paper presents preliminary results of laboratory tests aimed at evaluating the easibility of the remediation of marine sediments, which are polluted by mercury and petroleum hydrocarbons, dredged at the bay of Augusta (SR, Italy). The treatment is composed of two sequential steps: in the first, a cement-based granular material is produced (based on a high performance concrete approach); then, the volatile and the semi-volatile compounds in the granular material are removed by a thermal desorption step. Treated materials could be reused or put into caissons, according to their mechanical properties and environmental compatibility. The experiments were focused on evaluating the effect of the process parameter values on: (i) the evolution of cement hydration reactions, (ii) thermal desorption removal efficiencies, (iii) leaching behaviour of the treated material. PMID:19705665

  11. History effects in the sedimentation of light aerosols in turbulence: the case of marine snow

    CERN Document Server

    Guseva, Ksenia; Feudel, Ulrike; Tél, Tamás

    2016-01-01

    We analyze the effect of the Basset history force on the sedimentation of nearly neutrally buoyant particles, exemplified by marine snow, in a three-dimensional turbulent flow. Particles are characterized by Stokes numbers much smaller than unity, and still water settling velocities, measured in units of the Kolmogorov velocity, of order one. The presence of the history force in the Maxey-Riley equation leads to individual trajectories which differ strongly from the dynamics of both inertial particles without this force, and ideal settling tracers. When considering, however, a large ensemble of particles, the statistical properties of all three dynamics become more similar. The main effect of the history force is a rather slow, power-law type convergence to an asymptotic settling velocity of the center of mass, which is found numerically to be the settling velocity in still fluid. The spatial extension of the ensemble grows diffusively after an initial ballistic growth lasting up to ca. one large eddy turnove...

  12. Determination of trace and toxic elements in marine sediments collected from the strait of Malacca, Malaysia

    International Nuclear Information System (INIS)

    The Strait of Malacca has been a major route for international trade with heavy traffic of large vessels navigating through the narrow waterway everyday. Beside, the Strait of Malacca has some natural ecosystem which requires proper protection from human activities. Therefore, the Malaysian government has initiated a project to monitor the pollution level at the Strait of Malacca. As a result, sampling expeditions had been conducted to collect marine samples to be analyzed for trace and toxic elements as well as organic pollutions and radionuclides. The focus of this report is to determine trace and toxic element concentration in surface sediment samples collected from 18 sampling locations at the Strait of Malacca was reported. (author)

  13. A New Natural Gamma Radiation Measurement System for Marine Sediment and Rock Analysis

    CERN Document Server

    Vasiliev, M A; Chubarian, G; Olsen, R; Bennight, C; Cobine, T; Fackler, D; Hastedt, M; Houpt, D; Mateo, Z; Vasilieva, Y B

    2010-01-01

    A new high-efficiency and low-background system for the measurement of natural gamma radioactivity in marine sediment and rock cores retrieved from beneath the seabed was designed, built, and installed on the JOIDES Resolution research vessel. The system includes eight large NaI(Tl) detectors that measure adjacent intervals of the core simultaneously, maximizing counting times and minimizing statistical error for the limited measurement times available during drilling expeditions. Effect to background ratio is maximized with passive lead shielding, including both ordinary and low-activity lead. Large-area plastic scintillator active shielding filters background associated with the high-energy part of cosmic radiation. The new system has at least an order of magnitude higher statistical reliability and significantly enhances data quality compared to other offshore natural gamma radiation (NGR) systems designed to measure geological core samples. Reliable correlations and interpretations of cored intervals are ...

  14. Optimizing sample pretreatment for compound-specific stable carbon isotopic analysis of amino sugars in marine sediment

    Science.gov (United States)

    Zhu, R.; Lin, Y.-S.; Lipp, J. S.; Meador, T. B.; Hinrichs, K.-U.

    2014-09-01

    Amino sugars are quantitatively significant constituents of soil and marine sediment, but their sources and turnover in environmental samples remain poorly understood. The stable carbon isotopic composition of amino sugars can provide information on the lifestyles of their source organisms and can be monitored during incubations with labeled substrates to estimate the turnover rates of microbial populations. However, until now, such investigation has been carried out only with soil samples, partly because of the much lower abundance of amino sugars in marine environments. We therefore optimized a procedure for compound-specific isotopic analysis of amino sugars in marine sediment, employing gas chromatography-isotope ratio mass spectrometry. The whole procedure consisted of hydrolysis, neutralization, enrichment, and derivatization of amino sugars. Except for the derivatization step, the protocol introduced negligible isotopic fractionation, and the minimum requirement of amino sugar for isotopic analysis was 20 ng, i.e., equivalent to ~8 ng of amino sugar carbon. Compound-specific stable carbon isotopic analysis of amino sugars obtained from marine sediment extracts indicated that glucosamine and galactosamine were mainly derived from organic detritus, whereas muramic acid showed isotopic imprints from indigenous bacterial activities. The δ13C analysis of amino sugars provides a valuable addition to the biomarker-based characterization of microbial metabolism in the deep marine biosphere, which so far has been lipid oriented and biased towards the detection of archaeal signals.

  15. Distribution of clay minerals in marine sediments off Chennai, Bay of Bengal, India:Indicators of sediment sources and transport processes

    Institute of Scientific and Technical Information of China (English)

    Subramanian VEERASINGAM; Ramdoss VENKATACHALAPATHY; Thirunavukkarasu RAMKUMAR

    2014-01-01

    Clay mineralogy, texture size and statistical analyses were carried out on surface sediments from the continental shelf of Chennai, Bay of Bengal, India. The purpose of this study is to characterize the clay mineral distribution and its relation to the hydrodynamics off Chennai to identify the sources and transport pathways of the marine sediments. Characterization of clay minerals in coastal sediments by Fourier Transform Infrared (FTIR) spectroscopy has provided the association of quartz, feldspar, kaolinite, chlorite, illite and iron oxides (magnetite and hematite) derived from river catchments and coastal erosion. Kaolinite, chlorite, illite, iron oxides, and organic matter are the dominant minerals in Cooum, and Adayar region. High quartz and feldspar zones were identified in Marina, which are being confined the sand zone and paralleling the coast. The strong relationships among the wave energy density, sand, quartz and carbonate revealed that wave induced littoral drift system play a dominant role in transportation and deposition of sediments in the Chennai coast. The sediment texture and minerals data are in agreement well with the previous results of hydrodynamics and littoral drift models in this region. Multivariate statistical analyses (correlation, cluster and factor analyses) were carried out and obtained results suggested that clay minerals and organic matter are trapped in silt and clay particles, whereas quartz, feldspar and carbonate are associated with sand particles. Results of sediment sources and transport processes from this study will be useful to predict the fate of the pollutants released from land or the potential change in sediment delivery to coastal areas.

  16. Impacts of human activities on distribution of sulfate-reducing prokaryotes and antibiotic resistance genes in marine coastal sediments of Hong Kong.

    Science.gov (United States)

    Guo, Feng; Li, Bing; Yang, Ying; Deng, Yu; Qiu, Jian-Wen; Li, Xiangdong; Leung, Kenneth My; Zhang, Tong

    2016-09-01

    Sulfate-reducing prokaryotes (SRPs) and antibiotic resistance genes (ARGs) in sediments could be biomarkers for evaluating the environmental impacts of human activities, although factors governing their distribution are not clear yet. By using metagenomic approach, this study investigated the distributions of SRPs and ARGs in marine sediments collected from 12 different coastal locations of Hong Kong, which exhibited different pollution levels and were classified into two groups based on sediment parameters. Our results showed that relative abundances of major SRP genera to total prokaryotes were consistently lower in the more seriously polluted sediments (P-value niche differentiation of SRPs and behavior of ARGs in marine coastal sediment. PMID:27297722

  17. Anodes Stimulate Anaerobic Toluene Degradation via Sulfur Cycling in Marine Sediments.

    Science.gov (United States)

    Daghio, Matteo; Vaiopoulou, Eleni; Patil, Sunil A; Suárez-Suárez, Ana; Head, Ian M; Franzetti, Andrea; Rabaey, Korneel

    2016-01-01

    Hydrocarbons released during oil spills are persistent in marine sediments due to the absence of suitable electron acceptors below the oxic zone. Here, we investigated an alternative bioremediation strategy to remove toluene, a model monoaromatic hydrocarbon, using a bioanode. Bioelectrochemical reactors were inoculated with sediment collected from a hydrocarbon-contaminated marine site, and anodes were polarized at 0 mV and +300 mV (versus an Ag/AgCl [3 M KCl] reference electrode). The degradation of toluene was directly linked to current generation of up to 301 mA m(-2) and 431 mA m(-2) for the bioanodes polarized at 0 mV and +300 mV, respectively. Peak currents decreased over time even after periodic spiking with toluene. The monitoring of sulfate concentrations during bioelectrochemical experiments suggested that sulfur metabolism was involved in toluene degradation at bioanodes. 16S rRNA gene-based Illumina sequencing of the bulk anolyte and anode samples revealed enrichment with electrocatalytically active microorganisms, toluene degraders, and sulfate-reducing microorganisms. Quantitative PCR targeting the α-subunit of the dissimilatory sulfite reductase (encoded by dsrA) and the α-subunit of the benzylsuccinate synthase (encoded by bssA) confirmed these findings. In particular, members of the family Desulfobulbaceae were enriched concomitantly with current production and toluene degradation. Based on these observations, we propose two mechanisms for bioelectrochemical toluene degradation: (i) direct electron transfer to the anode and/or (ii) sulfide-mediated electron transfer. PMID:26497463

  18. A transfer function for the prediction of gas hydrate inventories in marine sediments

    Directory of Open Access Journals (Sweden)

    M. Marquardt

    2010-02-01

    Full Text Available A simple prognostic tool for gas hydrate (GH quantification in marine sediments is presented based on a diagenetic transport-reaction model approach. One of the most crucial factors for the application of diagenetic models is the accurate formulation of microbial degradation rates of particulate organic carbon (POC and the coupled biogenic CH4 formation. Wallmann et al. (2006 suggested a kinetic formulation considering the ageing effects of POC and accumulation of reaction products (CH4, CO2 in the pore water. This model is applied to data sets of several ODP sites in order to test its general validity. Based on a thorough parameter analysis considering a wide range of environmental conditions, the POC accumulation rate (POCar in g/cm2/yr and the thickness of the gas hydrate stability zone (GHSZ in m were identified as the most important and independent controls for biogenic GH formation. Hence, depth-integrated GH inventories in marine sediments (GHI in g of CH4 per cm2 seafloor area can be estimated as:

    GHI = a · POCar · GHSZb · exp (−GHSZc/POCar/d + e

    with a = 0.00214, b = 1.234, c = −3.339, d = 0.3148, e = −10.265.

    Several tests indicate that the transfer function gives a realistic approximation of the minimum potential GH inventory of low gas flux (LGF systems. The overall advantage of the presented function is its simplicity compared to complex numerical models: only two easily accessible parameters are needed.

  19. A transfer function for the prediction of gas hydrate inventories in marine sediments

    Directory of Open Access Journals (Sweden)

    M. Marquardt

    2010-09-01

    Full Text Available A simple prognostic tool for gas hydrate (GH quantification in marine sediments is presented based on a diagenetic transport-reaction model approach. One of the most crucial factors for the application of diagenetic models is the accurate formulation of microbial degradation rates of particulate organic carbon (POC and the coupled formation of biogenic methane. Wallmann et al. (2006 suggested a kinetic formulation considering the ageing effects of POC and accumulation of reaction products (CH4, CO2 in the pore water. This model is applied to data sets of several ODP sites in order to test its general validity. Based on a thorough parameter analysis considering a wide range of environmental conditions, the POC accumulation rate (POCar in g/m2/yr and the thickness of the gas hydrate stability zone (GHSZ in m were identified as the most important and independent controls for biogenic GH formation. Hence, depth-integrated GH inventories in marine sediments (GHI in g of CH4 per cm2 seafloor area can be estimated as:

    GHI = a · POCar · GHSZb · exp (– GHSZc/POCar/d + e

    with a = 0.00214, b = 1.234, c = –3.339,

            d = 0.3148, e = –10.265.

    The transfer function gives a realistic first order approximation of the minimum GH inventory in low gas flux (LGF systems. The overall advantage of the presented function is its simplicity compared to the application of complex numerical models, because only two easily accessible parameters need to be determined.

  20. Anodes Stimulate Anaerobic Toluene Degradation via Sulfur Cycling in Marine Sediments

    Science.gov (United States)

    Daghio, Matteo; Vaiopoulou, Eleni; Patil, Sunil A.; Suárez-Suárez, Ana; Head, Ian M.

    2015-01-01

    Hydrocarbons released during oil spills are persistent in marine sediments due to the absence of suitable electron acceptors below the oxic zone. Here, we investigated an alternative bioremediation strategy to remove toluene, a model monoaromatic hydrocarbon, using a bioanode. Bioelectrochemical reactors were inoculated with sediment collected from a hydrocarbon-contaminated marine site, and anodes were polarized at 0 mV and +300 mV (versus an Ag/AgCl [3 M KCl] reference electrode). The degradation of toluene was directly linked to current generation of up to 301 mA m−2 and 431 mA m−2 for the bioanodes polarized at 0 mV and +300 mV, respectively. Peak currents decreased over time even after periodic spiking with toluene. The monitoring of sulfate concentrations during bioelectrochemical experiments suggested that sulfur metabolism was involved in toluene degradation at bioanodes. 16S rRNA gene-based Illumina sequencing of the bulk anolyte and anode samples revealed enrichment with electrocatalytically active microorganisms, toluene degraders, and sulfate-reducing microorganisms. Quantitative PCR targeting the α-subunit of the dissimilatory sulfite reductase (encoded by dsrA) and the α-subunit of the benzylsuccinate synthase (encoded by bssA) confirmed these findings. In particular, members of the family Desulfobulbaceae were enriched concomitantly with current production and toluene degradation. Based on these observations, we propose two mechanisms for bioelectrochemical toluene degradation: (i) direct electron transfer to the anode and/or (ii) sulfide-mediated electron transfer. PMID:26497463

  1. The effect of organic matter and oxygen on the degradation of bacterial membrane lipids in marine sediments

    Science.gov (United States)

    Harvey, H. Rodger; Fallon, Robert D.; Patton, John S.

    1986-05-01

    The biodegradation of purified radiolabelled membrane lipids from a methanogenic bacterium and a pseudomonad were investigated in mangrove, beach and high marsh marine sediments under aerobic and anaerobic conditions. The effect of organic matter on the amount and rate of degradation was also examined by supplementing beach sediments with humic acids. In aerobic sediments, CO 2 was the major product of lipid degradation while under anaerobic conditions both CO 2 and CH 4 were major end products and the overall rates were reduced (up to 40%) relative to aerobic conditions. Total bacterial numbers increased during all incubations with the largest increases occurring in anaerobic sediments supplemented with humic acids. No lipid degradation occurred in aerobic or anaerobic sediments treated with formaldehyde or autoclaving. In low organic beach sediments, the ester-linked phospholipid of the pseudomonad was degraded much more rapidly than the diphytanyl glycerol diether of the methanogen with 69% of the phospholipid degraded in 96 hours versus only 4% of the methanogen lipid. Lipid degradation in both aerobic and anaerobic sediments was highly correlated to organic matter content with increasing amounts of organic matter inhibiting degradation. Long incubations (75 days) of the diphytanyl glycerol ether resulted in 51% degraded to CO 2 in low (0.5%) organic mangrove sediments while only 9% was mineralized in high (10.8%) organic marsh sediments. Physicochemical sorption of membrane lipids to the organic matrix is proposed as a mechanism which protects membrane lipids from microbial attack and degradation.

  2. Heavy metal content in coral reef sediments from Red Sea of Yemen and its significance on marine environment

    Institute of Scientific and Technical Information of China (English)

    Nabil A. AL-SHAWAFI; Abdulhakeem AL-KHOLIDI; Aref M.O. AL-JABALI

    2009-01-01

    In order to determine and assess the concentrations of trace elements in coral reefs sediments from Red Sea of Yemen, sediment samples were collected, treated and analyzed for cadmium, chromium, cobalt, copper, manganese, nickel, iead, iron, zinc and vanadium by the atomic absorption spectrometric analysis. The result is that cadmium, cobalt and lead concentrations were high and other elements are low or the same as natural background. It is concluded that the high cadmium, cobalt and lead levels in coral reefs sediments will have negative effects on marine life of the sites, so further researches are needed to characterize the sources fate, biogeochemical processes and impacts of these trace elements on coral reefs and marine of the region.

  3. Sources of polycyclic aromatic hydrocarbons (PAHs) pollution in marine sediment from Tuanku Abdul Rahman National Park, Sabah

    International Nuclear Information System (INIS)

    The concentrations of parent and alkyl Polycyclic Aromatic Hydrocarbons (PAHs) in marine sediment samples collected from Tuanku Abdul Rahman National Park, Sabah were determined by using GC-MS. The ratio of anthracene to anthracene plus phenanthrene, fluoranthene to fluoranthene plus pyrene, benz[a]anthracene to benz[a]anthracene plus chrysene and indeno[1,2,3-cd]pyrene to indeno[1,2,3-cd]pyrene plus benzo[g,h,i]perylene, compounds were used to identify the sources of PAHs pollution. The total concentration of parent and alkyl PAHs are ranged from 121.7 to 191.5 ng/ g dry weight. The concentrations of PAHs pollution in sediments were categorised as a moderate polluted. The ratio values of PAHs compound indicate the origin source of PAHs pollutions in marine sediment sample of Tuanku Abdul Rahman National Park were originated from fossil fuel combustion (pyrolytic). (author)

  4. Origin and geochemical behavior of uranium in marine sediments. Utilization of the {sup 234}U/{sup 238}U ratio in marine geochemistry; Origine et comportement geochimique de l`uranium dans les sediments marins. Utilisation du rapport ({sup 234}U/{sup 238}U) en geochimie marine

    Energy Technology Data Exchange (ETDEWEB)

    Organo, Catherine [Paris-11 Univ., 91 - Orsay (France)

    1997-01-20

    The first part of this thesis presents the current situation of knowledge of uranium in marine environment. The second part describes the methods of analysis as well as the material support of the study, i.e., the sediments and marine deposits investigated. The third part is dedicated to the study of uranium mobility in marine sediments characterized by detrital terrigenous composition (pelagic clays). This approach allowed quantifying the entering and leaving flux of uranium after the sediment settling and, to discuss, on this basis, the consequences on the uranium oceanic balance. In the third part the origin and behavior of uranium in zones of high surface productivity is studied. The uranium enrichments observed in the hemi-pelagic sediments of the EUMELI (J.G.O.F.S.-France) programme will constitute a material of study adequate for measuring the variations in the {sup 234}U/2{sup 38U} ratio in solid phase, in response to the oxido-reducing characteristics of the sediment. Thus establishing the origin of the trapped uranium has been possible. Also, the nature of the sedimentary phases related to uranium in bio-genetic sediments in the Austral Ocean was determined. Thus a relationship between the variations in the {sup 234}U/{sup 238} and the diagenetic transformations was possible to establish. Finally in the fifth part a study of the behavior of uranium in a polymetallic shell characteristic for deposits of hydrogenized origin 146 refs., 57 figs., 23 tabs.

  5. Determination of methylmercury in marine sediment samples: Method validation and occurrence data

    International Nuclear Information System (INIS)

    Highlights: • A method for MeHg determination at trace level in marine sediments is completely validated. • Validation is performed according to ISO-17025 and Eurachem guidelines. • The extraction efficiency of four sample preparation procedures is evaluated. • The uncertainty budget is used as a tool for evaluation of main uncertainty contributors. • Comparison with independent methods yields good agreement within stated uncertainty. - Abstract: The determination of methylmercury (MeHg) in sediment samples is a difficult task due to the extremely low MeHg/THg (total mercury) ratio and species interconversion. Here, we present the method validation of a cost-effective fit-for-purpose analytical procedure for the measurement of MeHg in sediments, which is based on aqueous phase ethylation, followed by purge and trap and hyphenated gas chromatography–pyrolysis–atomic fluorescence spectrometry (GC–Py–AFS) separation and detection. Four different extraction techniques, namely acid and alkaline leaching followed by solvent extraction and evaporation, microwave-assisted extraction with 2-mercaptoethanol, and acid leaching, solvent extraction and back extraction into sodium thiosulfate, were examined regarding their potential to selectively extract MeHg from estuarine sediment IAEA-405 certified reference material (CRM). The procedure based on acid leaching with HNO3/CuSO4, solvent extraction and back extraction into Na2S2O3 yielded the highest extraction recovery, i.e., 94 ± 3% and offered the possibility to perform the extraction of a large number of samples in a short time, by eliminating the evaporation step. The artifact formation of MeHg was evaluated by high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC–ICP–MS), using isotopically enriched Me201Hg and 202Hg and it was found to be nonexistent. A full validation approach in line with ISO 17025 and Eurachem guidelines was followed. With this in

  6. Determination of methylmercury in marine sediment samples: Method validation and occurrence data

    Energy Technology Data Exchange (ETDEWEB)

    Carrasco, Luis; Vassileva, Emilia, E-mail: e.vasileva-veleva@iaea.org

    2015-01-01

    Highlights: • A method for MeHg determination at trace level in marine sediments is completely validated. • Validation is performed according to ISO-17025 and Eurachem guidelines. • The extraction efficiency of four sample preparation procedures is evaluated. • The uncertainty budget is used as a tool for evaluation of main uncertainty contributors. • Comparison with independent methods yields good agreement within stated uncertainty. - Abstract: The determination of methylmercury (MeHg) in sediment samples is a difficult task due to the extremely low MeHg/THg (total mercury) ratio and species interconversion. Here, we present the method validation of a cost-effective fit-for-purpose analytical procedure for the measurement of MeHg in sediments, which is based on aqueous phase ethylation, followed by purge and trap and hyphenated gas chromatography–pyrolysis–atomic fluorescence spectrometry (GC–Py–AFS) separation and detection. Four different extraction techniques, namely acid and alkaline leaching followed by solvent extraction and evaporation, microwave-assisted extraction with 2-mercaptoethanol, and acid leaching, solvent extraction and back extraction into sodium thiosulfate, were examined regarding their potential to selectively extract MeHg from estuarine sediment IAEA-405 certified reference material (CRM). The procedure based on acid leaching with HNO{sub 3}/CuSO{sub 4}, solvent extraction and back extraction into Na{sub 2}S{sub 2}O{sub 3} yielded the highest extraction recovery, i.e., 94 ± 3% and offered the possibility to perform the extraction of a large number of samples in a short time, by eliminating the evaporation step. The artifact formation of MeHg was evaluated by high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC–ICP–MS), using isotopically enriched Me{sup 201}Hg and {sup 202}Hg and it was found to be nonexistent. A full validation approach in line with ISO 17025 and

  7. Development and application of a marine sediment pore-water toxicity test using Ulva fasciata zoospores

    Energy Technology Data Exchange (ETDEWEB)

    Hooten, R.L.; Carr, R.S. [Texas A and M Univ., Corpus Christi, TX (United States). Geological Survey

    1998-01-01

    An acute (96 h) pore-water toxicity test protocol using germination and growth of Ulva fasciata zoospores as endpoints was developed to test the toxicity of marine and estuarine sediment pore-water samples. Tests with an organic toxicant (sodium dodecyl sulfate; SDS), three metals (Cd, Cu, and Zn), and ammonia (NH{sub 3}) were conducted to determine zoospore sensitivity. Zoospore germination and gametophyte growth were as sensitive to SDS as sea urchin (Arbacia punctulata) fertilization and embryological development. Zoospore sensitivity to metals was greater than or comparable to that of adult macroalgae. Zoospores were less sensitive to NH{sub 3} than were other commonly used toxicity test organisms. Test results using this algal assay with sediment pore-water samples with high NH{sub 3} concentrations were compared with results from sea urchin fertilization and embryological development tests for the same samples. Ulva fasciata zoospore germination was not affected by samples with high NH{sub 3} concentrations that were toxic in both sea urchin tests. Zoospore tolerance of NH{sub 3} and sensitivity to other contaminants indicate that their response may be useful in toxicity identification evaluation studies with pore-water samples that contain high concentrations of unionized NH{sub 3}.

  8. Development and application of a marine sediment pore-water toxicity test using Ulva fasciata zoospores

    Science.gov (United States)

    Hooten, R.L.; Carr, R.S.

    1998-01-01

    An acute (96 h) pore-water toxicity test protocol using germination and growth of Ulva fasciata zoospores as endpoints was developed to test the toxicity of marine and estuarine sediment pore-water samples. Tests with an organic toxicant (sodium dodecyl sulfate; SDS), three metals (Cd, Cu, and Zn), and ammonia (NH3) were conducted to determine zoospore sensitivity. Zoospore germination and gametophyte growth were as sensitive to SDS as sea urchin (Arbacia punctulata) fertilization and embryological development. Zoospore sensitivity to metals was greater than or comparable to that of adult macroalgae. Zoospores were less sensitive to NH3 than were other commonly used toxicity test organisms. Test results using this algal assay with sediment pore-water samples with high NH3 concentrations were compared with results from sea urchin fertilization and embryological development tests for the same samples. Ulva fasciata zoospore germination was not affected by samples with high NH3 concentrations that were toxic in both sea urchin tests. Zoospore tolerance of NH3 and sensitivity to other contaminants indicate that their response may be useful in toxicity identification evaluation studies with pore-water samples that contain high concentrations of unionized NH3.

  9. Equilibrium oxygen isotope behavior of sulfate in marine sediments: A new paradigm

    Science.gov (United States)

    Blake, R.; Boettcher, M.; Surkov, A.; Ferdelman, T.; Jorgensen, B.

    2006-05-01

    We have determined the oxygen (18O/16O) and sulfur (34S/32S) isotope ratios of porewater sulfate to depths of over 400 mbsf in sediments from open-ocean and upwelling sites in the Eastern Equatorial Pacific ocean. Sulfate δ18O ranges from near-normal seawater values (9.5 permil) at organic-poor open-ocean sites, to approximately 30 permil at sites with higher organic matter content and higher associated microbial activity. Depth-correlative trends of δ18O, δ34S, alkalinity, methane, ammonium and the presence of sulfide, indicate significant oxidation of sedimentary organic matter by sulfate-reducing microbial populations as well as anaerobic oxidation of methane. δ18O ?SO4 values at low-activity sites reveal the presence of significant microbial sulfur-cycling activity despite relatively flat sulfate concentration and δ34S profiles. This activity may include contributions from several processes including: enzyme-catalyzed equilibration between oxygen in sulfate and water superimposed upon microbial sulfate reduction, sulfide oxidation, and bacterial disproportionation of sulfur intermediates. Positive correlation between water and sulfate δ18O values supports sulfate-water O isotope exchange as the dominant process controlling porewater sulfate δ18O values. Results of this study indicate that coupled measurements of S and O isotope ratios of porewater sulfate are essential for interpreting microbial sulfur cycling in marine sediments.

  10. Effect of anaerobic contributions to the uranium content in marine sediments

    International Nuclear Information System (INIS)

    In this work a sediment group obtained in the seabed near the mouth of the Santiago River, physical analyzes show that there is little activity of microscopic marine life, revealed by exoskeletons of foraminifera. Although the amount of organic matter occurs normally, around 20%, is assumed that this contribution is due to the large amount of organic waste scattered by the effluent of the river, causing an abnormally high anaerobic activity, clearly shown by the large amount of pyrite specific framboids found along the nucleus profile of 23 cm of sediment. In the analyzed fractions the uranium concentration and its isotope ratio was studied: which vary from 3.19 Bq/kg for the more superficial fractions down gradually to less than 1 Bq/kg for deeper fractions. An outstanding fact is that the surface fractions have an isotope ratio 234U/238U unusually low for fractions 1-4 cm of deep, close to 0.4, indicating a strong reaction of few years ago on the radiogenic descendants of 238U, leaching essentially the 234Th and causing this abnormal radioactive imbalance. The plutonium has become an element found commonly in the surface layers of the sea and coastlines, finding in the top layer an activity of 2.78 Bq/kg (239Pu + 240Pu). The high contamination of the mouth of Santiago River has changed the conditions of the micro fauna as well as of the chemical equilibrium of the natural elements. (Author)

  11. Forsmark site investigation. Investigation of marine and lacustrine sediment in lakes. Field data 2003

    International Nuclear Information System (INIS)

    The aim of this activity is to describe the aerial and stratigraphical distribution of marine and lacustrine sediment i.e. sediment overlaying the glacial till and/or bedrock surface, in lakes in the Forsmark area. The investigation is carried out within areas where mapping of unconsolidated Quaternary deposits is presently carried out. Since small and shallow lakes cover a large part of the region, this work will give important information on the distribution and stratigraphy of sedimentary deposits not included in the regular mapping of unconsolidated Quaternary deposits within the site investigation programme. Samples were also collected for laboratory analyses of grain size distribution, mineralogical composition as well as the total content of C, N and S and calcium carbonate. The analyses will be carried out on selected samples of representative sedimentary units in order to characterise the chemical and physical properties of the unconsolidated deposits. The analytical data will be useful for the hydrogeological modelling and for models of the Quaternary evolution of the area. The mineralogical analyses of clay may provide information on the origin of the clay particles. One stratigraphic sequence from Lake Eckarfjaerden will be stored for later analyses, e.g. pollen analysis. This report includes field data from spring 2003. Together, the field data and the forthcoming results from the laboratory analyses will form the basis for construction of stratigraphical profiles to be presented in a following report in the fall 2003

  12. Treatability assessment of polycyclic aromatic hydrocarbons contaminated marine sediments using permanganate, persulfate and Fenton oxidation processes.

    Science.gov (United States)

    Shih, Yu-Jen; Binh, Nguyen Thanh; Chen, Chiu-Wen; Chen, Chih-Feng; Dong, Cheng-Di

    2016-05-01

    Various chemical oxidation techniques, such as potassium permanganate (KMnO4), sodium persulfate (Na2S2O8), Fenton (H2O2/Fe(2+)), and the modified persulfate and Fenton reagents (activated by ferrous complexes), were carried out to treat marine sediments that were contaminated with polycyclic aromatic hydrocarbons (PAHs) and dredged from Kaohsiung Harbor in Taiwan. Experimental results revealed that KMnO4 was the most effective of the tested oxidants in PAH degradation. Owing to the high organic matter content in the sediment that reduced the efficiencies of Na2S2O8 and regular Fenton reactions, a large excess of oxidant was required. Nevertheless, KH2PO4, Na4P2O7 and four chelating agents (EDTA, sodium citrate, oxalic acid, and sodium oxalate) were utilized to stabilize Fe(II) in activating the Na2S2O8 and Fenton oxidations, while Fe(II)-citrate remarkably promoted the PAH degradation. Increasing the molecular weight and number of rings of PAH did not affect the overall removal efficiencies. The correlation between the effectiveness of the oxidation processes and the physicochemical properties of individual PAH was statistically analyzed. The data implied that the reactivity of PAH (electron affinity and ionization potential) affected its treatability more than did its hydrophobicity (Kow, Koc and Sw), particularly using experimental conditions under which PAHs could be effectively oxidized. PMID:26915591

  13. MOSAIC: An organic geochemical and sedimentological database for marine surface sediments

    Science.gov (United States)

    Tavagna, Maria Luisa; Usman, Muhammed; De Avelar, Silvania; Eglinton, Timothy

    2015-04-01

    Modern ocean sediments serve as the interface between the biosphere and the geosphere, play a key role in biogeochemical cycles and provide a window on how contemporary processes are written into the sedimentary record. Research over past decades has resulted in a wealth of information on the content and composition of organic matter in marine sediments, with ever-more sophisticated techniques continuing to yield information of greater detail and as an accelerating pace. However, there has been no attempt to synthesize this wealth of information. We are establishing a new database that incorporates information relevant to local, regional and global-scale assessment of the content, source and fate of organic materials accumulating in contemporary marine sediments. In the MOSAIC (Modern Ocean Sediment Archive and Inventory of Carbon) database, particular emphasis is placed on molecular and isotopic information, coupled with relevant contextual information (e.g., sedimentological properties) relevant to elucidating factors that influence the efficiency and nature of organic matter burial. The main features of MOSAIC include: (i) Emphasis on continental margin sediments as major loci of carbon burial, and as the interface between terrestrial and oceanic realms; (ii) Bulk to molecular-level organic geochemical properties and parameters, including concentration and isotopic compositions; (iii) Inclusion of extensive contextual data regarding the depositional setting, in particular with respect to sedimentological and redox characteristics. The ultimate goal is to create an open-access instrument, available on the web, to be utilized for research and education by the international community who can both contribute to, and interrogate the database. The submission will be accomplished by means of a pre-configured table available on the MOSAIC webpage. The information on the filled tables will be checked and eventually imported, via the Structural Query Language (SQL), into

  14. Plutonium in Baltic sediments

    International Nuclear Information System (INIS)

    Marine sediments accumulate the bulk of plutonium produced by nuclear tests. The nuclear power industry will form an additional source of plutonium, and it is important to determine the present background levels of plutonium in sediments and to compare the accumulation rate in the Baltic with that in other areas of the world. Plutonium was determined on four sediment cores collected from the Baltic Sea in 1974 and 1975. Two of the samples were from oxygenated coastal sediment with benthic life and two cores were collected from deep basins in the Baltic at depths of 183 m and 164 m where the bottoms were anoxic, with no benthic life, and where the rate of sedimentation is rather high. Data are presented on the Pu-239,240 content of the sediment cores as is pCi/kg dry wt in the different core sections. The highest plutonium concentrations were found near the surface, at depths of 0 to 8 cm. In all cores the plutonium concentration decreases sharply at a depth of about 6 to 8 cm

  15. Deep-Sea, Deep-Sequencing: Metabarcoding Extracellular DNA from Sediments of Marine Canyons.

    Directory of Open Access Journals (Sweden)

    Magdalena Guardiola

    Full Text Available Marine sediments are home to one of the richest species pools on Earth, but logistics and a dearth of taxonomic work-force hinders the knowledge of their biodiversity. We characterized α- and β-diversity of deep-sea assemblages from submarine canyons in the western Mediterranean using an environmental DNA metabarcoding. We used a new primer set targeting a short eukaryotic 18S sequence (ca. 110 bp. We applied a protocol designed to obtain extractions enriched in extracellular DNA from replicated sediment corers. With this strategy we captured information from DNA (local or deposited from the water column that persists adsorbed to inorganic particles and buffered short-term spatial and temporal heterogeneity. We analysed replicated samples from 20 localities including 2 deep-sea canyons, 1 shallower canal, and two open slopes (depth range 100-2,250 m. We identified 1,629 MOTUs, among which the dominant groups were Metazoa (with representatives of 19 phyla, Alveolata, Stramenopiles, and Rhizaria. There was a marked small-scale heterogeneity as shown by differences in replicates within corers and within localities. The spatial variability between canyons was significant, as was the depth component in one of the canyons where it was tested. Likewise, the composition of the first layer (1 cm of sediment was significantly different from deeper layers. We found that qualitative (presence-absence and quantitative (relative number of reads data showed consistent trends of differentiation between samples and geographic areas. The subset of exclusively benthic MOTUs showed similar patterns of β-diversity and community structure as the whole dataset. Separate analyses of the main metazoan phyla (in number of MOTUs showed some differences in distribution attributable to different lifestyles. Our results highlight the differentiation that can be found even between geographically close assemblages, and sets the ground for future monitoring and conservation

  16. Deep-Sea, Deep-Sequencing: Metabarcoding Extracellular DNA from Sediments of Marine Canyons.

    Science.gov (United States)

    Guardiola, Magdalena; Uriz, María Jesús; Taberlet, Pierre; Coissac, Eric; Wangensteen, Owen Simon; Turon, Xavier

    2015-01-01

    Marine sediments are home to one of the richest species pools on Earth, but logistics and a dearth of taxonomic work-force hinders the knowledge of their biodiversity. We characterized α- and β-diversity of deep-sea assemblages from submarine canyons in the western Mediterranean using an environmental DNA metabarcoding. We used a new primer set targeting a short eukaryotic 18S sequence (ca. 110 bp). We applied a protocol designed to obtain extractions enriched in extracellular DNA from replicated sediment corers. With this strategy we captured information from DNA (local or deposited from the water column) that persists adsorbed to inorganic particles and buffered short-term spatial and temporal heterogeneity. We analysed replicated samples from 20 localities including 2 deep-sea canyons, 1 shallower canal, and two open slopes (depth range 100-2,250 m). We identified 1,629 MOTUs, among which the dominant groups were Metazoa (with representatives of 19 phyla), Alveolata, Stramenopiles, and Rhizaria. There was a marked small-scale heterogeneity as shown by differences in replicates within corers and within localities. The spatial variability between canyons was significant, as was the depth component in one of the canyons where it was tested. Likewise, the composition of the first layer (1 cm) of sediment was significantly different from deeper layers. We found that qualitative (presence-absence) and quantitative (relative number of reads) data showed consistent trends of differentiation between samples and geographic areas. The subset of exclusively benthic MOTUs showed similar patterns of β-diversity and community structure as the whole dataset. Separate analyses of the main metazoan phyla (in number of MOTUs) showed some differences in distribution attributable to different lifestyles. Our results highlight the differentiation that can be found even between geographically close assemblages, and sets the ground for future monitoring and conservation efforts on

  17. Metal release from contaminated estuarine sediment under pH changes in the marine environment.

    Science.gov (United States)

    Martín-Torre, M Camino; Payán, M Cruz; Verbinnen, Bram; Coz, Alberto; Ruiz, Gema; Vandecasteele, Carlo; Viguri, Javier R

    2015-04-01

    The contaminant release from estuarine sediment due to pH changes was investigated using a modified CEN/TS 14429 pH-dependence leaching test. The test is performed in the range of pH values of 0-14 using deionised water and seawater as leaching solutions. The experimental conditions mimic different circumstances of the marine environment due to the global acidification, carbon dioxide (CO2) leakages from carbon capture and sequestration technologies, and accidental chemical spills in seawater. Leaching test results using seawater as leaching solution show a better neutralisation capacity giving slightly lower metal leaching concentrations than when using deionised water. The contaminated sediment shows a low base-neutralisation capacity (BNCpH 12 = -0.44 eq/kg for deionised water and BNCpH 12 = -1.38 eq/kg for seawater) but a high acid-neutralisation capacity when using deionised water (ANCpH 4 = 3.58 eq/kg) and seawater (ANCpH 4 = 3.97 eq/kg). Experimental results are modelled with the Visual MINTEQ geochemical software to predict metal release from sediment using both leaching liquids. Surface adsorption to iron- and aluminium-(hydr)oxides was applied for all studied elements. The consideration of the metal-organic matter binding through the NICA-Donnan model and Stockholm Humic Model for lead and copper, respectively, improves the former metal release prediction. Modelled curves can be useful for the environmental impact assessment of seawater acidification due to its match with the experimental values. PMID:25680769

  18. ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Thurman E. Scott, Jr., Ph.D.; Younane Abousleiman, Ph.D.; Musharraf Zaman, Ph.D., P.E.

    2001-07-01

    Mechanically weak formations, such as chalks, high porosity sandstones, and marine sediments, pose significant problems for oil and gas operators. Problems such as compaction, subsidence, and loss of permeability can affect reservoir production operations. For example, the unexpected subsidence of the Ekofisk chalk in the North Sea required over one billion dollars to re-engineer production facilities to account for losses created during that compaction (Sulak 1991). Another problem in weak formations is that of shallow water flows (SWF). Deep water drilling operations sometimes encounter cases where the marine sediments, at shallow depths just below the seafloor, begin to uncontrollably flow up and around the drill pipe. SWF problems created a loss of $150 million for the Ursa development project in the U.S. Gulf Coast SWF (Furlow 1998a,b; 1999a,b). The goal of this project is to provide a database on both the rock mechanical properties and the geophysical properties of weak rocks and sediments. These could be used by oil and gas companies to detect, evaluate, and alleviate potential production and drilling problems. The results will be useful in, for example, pre-drill detection of events such as SWF's by allowing a correlation of seismic data (such as hazard surveys) to rock mechanical properties. The data sets could also be useful for 4-D monitoring of the compaction and subsidence of an existing reservoir and imaging the zones of damage. During the second quarter of the project the research team has: (1) completed acoustic sensor construction, (2) conducted reconnaissance tests to map the deformational behaviors of the various rocks, (3) developed a sample assembly for the measurement of dynamic elastic and poroelastic parameters during triaxial testing, and (4) conducted a detailed review of the scientific literature and compiled a bibliography of that review. During the first quarter of the project the research team acquired several rock types for

  19. Seasonality and depth distribution of the abundance and activity of ammonia oxidizing microorganisms in marine coastal sediments (North Sea

    Directory of Open Access Journals (Sweden)

    Yvonne Antonia Lipsewers

    2014-09-01

    Full Text Available Microbial processes such as nitrification and anaerobic ammonium oxidation (anammox are important for nitrogen cycling in marine sediments. Seasonal variations of archaeal and bacterial ammonia oxidizers (AOA and AOB and anammox bacteria, as well as the environmental factors affecting these groups, are not well studied. We have examined the seasonal and depth distribution of the abundance and potential activity of these microbial groups in coastal marine sediments of the southern North Sea. This was achieved by quantifying specific intact polar lipids (IPLs as well as the abundance and gene expression of their 16S rRNA gene, the ammonia monooxygenase subunit A (amoA gene of AOA and AOB, and the hydrazine synthase (hzsA gene of anammox bacteria. AOA, AOB and anammox bacteria were detected and transcriptionally active down to 12 cm sediment depth. In all seasons, the abundance of AOA was higher compared to the AOB abundance suggesting that AOA play a more dominant role in aerobic ammonia oxidation in these sediments. Anammox bacteria were abundant and active even in oxygenated and bioturbated parts of the sediment. The abundance of AOA and AOB was relatively stable with depth and over the seasonal cycle, while anammox bacteria abundance and transcriptional activity were highest in August. North Sea sediments thus seem to provide a common, stable, ecological niche for AOA, AOB and anammox bacteria.

  20. Effects of the antibiotic ciprofloxacin on the bacterial community structure and degradation of pyrene in marine sediment

    International Nuclear Information System (INIS)

    The ecological consequences of antibiotics in the aquatic environment have been an issue of concern over the past years due to the potential risk for negative effects on indigenous microorganisms. Microorganisms provide important ecosystem services, such as nutrient recycling, organic matter mineralization and degradation of pollutants. In this study, effects of exposure to the antibiotic ciprofloxacin on the bacterial diversity and pollutant degradation in natural marine sediments were studied using molecular methods (T-RFLP) in combination with radiorespirometry. In a microcosm experiment, sediment spiked with 14C-labelled pyrene was exposed to five concentrations of ciprofloxacin (0, 20, 200, 1000 and 2000 μg L-1) in a single dose to the overlying water. The production of 14CO2 (i.e. complete mineralization of pyrene) was measured during 11 weeks. Sediment samples for bacterial community structure analysis were taken after 7 weeks. Results showed a significant dose-dependent inhibition of pyrene mineralization measured as the total 14CO2 production. The nominal EC50 was calculated to 560 μg L-1, corresponding to 0.4 μg/kg d.w. sediment. The lowest effect concentration on the bacterial community structure was 200 μg L-1, which corresponds to 0.1 μg/kg d.w. sediment. Our results show that antibiotic pollution can be a potential threat to both bacterial diversity and an essential ecosystem service they perform in marine sediment

  1. Modelling the cohesive sediment transport in the marine environment: the case of Thermaikos Gulf

    Directory of Open Access Journals (Sweden)

    Y. N. Krestenitis

    2007-01-01

    Full Text Available The transport of fine-grained sediments in the marine environment entails risks of pollutant intrusions from substances absorbed onto the cohesive flocks' surface, gradually released to the aquatic field. These substances include nutrients such as nitrate, phosphate and silicate compounds from drainage from fertilization of adjacent cultivated areas that enter the coastal areas through rivers and streams, or trace metals as remainders from urban and industrial activities. As a consequence, knowledge on the motion and distribution of sediment particles coming from a given pollutant source is expected to provide the 'bulk' information on pollutant distribution, necessary for determining the region of influence of the source and to estimate probable trophic levels of the seawater and potential environmental risks. In that aim a numerical model has been developed to predict the fate of the sediments introduced to the marine environment from different pollution sources, such as river outflows, erosion of the seabed, aeolian transported material and drainage systems. The proposed three-dimensional mathematical model is based on the particle tracking method, according to which matter concentration is expressed by particles, each representing a particular amount of sedimentary mass, passively advected and dispersed by the currents. The processes affecting characteristics and propagation of sedimentary material in the marine environment, incorporated in the parameterization, apart from advection and dispersion, include cohesive sediment and near-bed processes. The movement of the particles along with variations in sedimentary characteristics and state, carried by each particle as personal information, are traced with time. Specifically, concerning transport processes, the local seawater velocity and the particle's settling control advection, whereas the random Brownian motion due to turbulence simulates turbulent diffusion. The

  2. Modelling the cohesive sediment transport in the marine environment: the case of Thermaikos Gulf

    Directory of Open Access Journals (Sweden)

    Y. N. Krestenitis

    2006-07-01

    Full Text Available The transport of fine-grained sediments in the marine environment entails risks of pollutant intrusions from substances absorbed onto the cohesive flocks' surface, gradually released to the aquatic field. These substances include nutrients such as nitrate, phosphate and silicate compounds from drainage from fertilization of adjacent cultivated areas that enter the coastal areas through rivers and streams, or trace metals as remainders from urban and industrial activities. As a consequence, knowledge on the motion and distribution of sediment particles coming from a given pollutant source is expected to provide the ''bulk'' information on pollutant distribution, necessary for determining the region of influence of the source and to estimate probable trophic levels of the seawater and potential environmental risks. In that aim a numerical model has been developed to predict the fate of the sediments introduced to the marine environment from different pollution sources, such as river outflows, erosion of the seabed, aeolian transported material and drainage systems.

    The proposed three-dimensional mathematical model is based on the particle tracking method, according to which matter concentration is expressed by particles, each representing a particular amount of sedimentary mass, passively advected and dispersed by the currents. The processes affecting characteristics and propagation of sedimentary material in the marine environment, incorporated in the parameterization, apart from advection and dispersion, include cohesive sediment and near-bed processes. The movement of the particles along with variations in sedimentary characteristics and state, carried by each particle as personal information, are traced with time. Specifically, concerning transport processes, the local seawater velocity and the particle's settling control advection, whereas the random Brownian motion due to turbulence simulates turbulent

  3. Depth-related influences on biodegradation rates of phenanthrene in polluted marine sediments of Puget Sound, WA

    International Nuclear Information System (INIS)

    A whole-core injection method was used to determine depth-related rates of microbial mineralization of 14C-phenanthrene added to both contaminated and clean marine sediments of Puget Sound, WA. For 26-day incubations under micro-aerobic conditions, conversions of 14C-phenanthrene to 14CO2 in heavily PAH-contaminated sediments from two sites in Eagle Harbor were much higher (up to 30%) than those in clean sediments from nearby Blakely Harbor (14C-phenanthrene degradation rates in the surface sediment horizons (0-3 cm) were more rapid (2-3 times) than in the deeper sediment horizons examined (>6 cm), especially in the most PAH polluted EH9 site. Differences in mineralization were associated with properties of the sediments as a function of sediment depth, including grain-size distribution, PAH concentration, total organic matter and total bacterial abundance. When strictly anaerobic incubations (in N2/H2/CO2 atmosphere) were used, the phenanthrene biodegradation rates at all sediment depths were two times slower than under micro-aerobic conditions, with methanogenesis observed after 24 days. The main rate-limiting factor for phenanthrene degradation under anaerobic conditions appeared to be the availability of suitable electron acceptors. Addition of calcium sulfate enhanced the first order rate coefficient (k 1 increased from 0.003 to 0.006 day-1), whereas addition of soluble nitrate, even at very low concentration (1 up to 0.11 day-1)

  4. Distribution and behavior of major and trace elements in Tokyo Bay, Mutsu Bay and Funka Bay marine sediments

    Energy Technology Data Exchange (ETDEWEB)

    Honda, Teruyuki [Musashi Inst. of Technology, Atomic Energy Research Laboratory, Kawasaki, Kanagawa (Japan); Kimura, Ken-ichiro [Musashi Inst. of Technology, Graduate School, Research Division in Engineering, Kawasaki, Kanagawa (Japan)

    2003-06-01

    Fourteen major and trace elements in marine sediment core samples collected from the coasts along eastern Japan, i.e. Tokyo Bay (II) (the recess), Tokyo Bay (IV) (the mouth), Mutsu Bay and Funka Bay and the Northwest Pacific basin as a comparative subject were determined by the instrumental neutron activation analysis (INAA). The sedimentation rates and sedimentary ages were calculated for the coastal sediment cores by the {sup 210}Pb method. The results obtained in this study are summarized as follows: (1) Lanthanoid abundance patterns suggested that the major origin of the sediments was terrigenous material. La*/Lu* and Ce*/La* ratios revealed that the sediments from Tokyo Bay (II) and Mutsu Bay more directly reflected the contribution from river than those of other regions. In addition, the Th/Sc ratio indicated that the coastal sediments mainly originated in the materials from the volcanic island-arcs, Japanese islands, whereas those from the Northwest Pacific mainly from the continent. (2) The correlation between the Ce/U and Th/U ratios with high correlation coefficients of 0.920 to 0.991 indicated that all the sediments from Tokyo Bay (II) and Funka Bay were in reducing conditions while at least the upper sediments from Tokyo Bay (IV) and Mutsu Bay were in oxidizing conditions. (3) It became quite obvious that the sedimentation mechanism and the sedimentation environment at Tokyo Bay (II) was different from those at Tokyo Bay (IV), since the sedimentation rate at Tokyo Bay (II) was approximately twice as large as that at Tokyo Bay (IV). The sedimentary age of the 5th layer (8{approx}10 cm in depth) from Funka Bay was calculated at approximately 1940{approx}50, which agreed with the time, 1943{approx}45 when Showa-shinzan was formed by the eruption of the Usu volcano. (author)

  5. Social, geographical, technical, environmental and economic approaches to strength marine sediment reuse options through CEAMaS project. -Center of resource – GIS -Economic model -Methodology -Reuse Theme: Sediment and society Sediment quality and perception Best practices in sediment management Building with dredged material

    OpenAIRE

    Debuigne, Tristan; Brakni, Samira; Sutton, Gerry; El Fgaier, Faycal; Harrington, Joe; MASSON, ERIC; Van Paassen, Leon; Lemiere, Bruno; Van Dessel, Johan; Wijdeveld, Arjan

    2015-01-01

    International audience Introduction: The management of marine sediment is a major issue for many European countries, and a range of different sediment management challenges have to be addressed across Europe. The volume of sediment to be dredged, the level of contamination and the physical properties of sediments vary widely in North Western Europe countries, in addition to the risk and potential cost of not dredging. In addressing these issues and its own history, each country has develop...

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

    Science.gov (United States)

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

    2012-12-01

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

  7. Application of silicone rubber passive samplers to investigate the bioaccumulation of PAHs by Nereis virens from marine sediments.

    Science.gov (United States)

    Yates, Kyari; Pollard, Pat; Davies, Ian M; Webster, Lynda; Moffat, Colin F

    2011-12-01

    The availability of polycyclic aromatic hydrocarbons (PAHs) from marine sediments to the ragworm (Nereis virens) was studied. Concentrations of PAHs in pore waters were determined using silicone rubber passive samplers. Calculated bioconcentration factors confirmed that partitioning of PAHs between the lipid phase of the polychaetes and pore water is a passive process. Low biota-sediment accumulation factors (BSAF) calculated using total sediment concentration suggested a fraction of the total PAH burden in the sediment may be strongly sorbed to organic carbon and not available to the polychaete. Organic carbon normalised concentrations of the potentially exchangeable fractions of contaminants and freely dissolved concentrations (measured using silicone rubber samplers) provide a better description of the observed bioaccumulation by the ragworms. These data indicate that the concept of availability should be included in environmental risk assessments based upon equilibrium partitioning models, and that silicone rubber samplers can provide the necessary information for these models. PMID:21906858

  8. Speciation of mercury and tin in marine sediments and biological matrix

    International Nuclear Information System (INIS)

    Full text: The aim of this study was to investigate for the first time, the distribution of mercury and tin compounds in marine sediments and mussel tissues collected in Bizerte lagoon, Tunisia during two seasons (summer and winter). Butyl-, Phenyl- and octyltin compounds were determined using a rapid speciation method. This analytical procedure is based on one-step simultaneous ethylation/extraction with sodium tetraethylborate in aqueous phase. Gas chromatography interfaced to Pulsed Flame Photometric Detection (GC-PFPD) was used to perform quantitative determination. Analysis of methylmercury MMHg and inorganic mercury Hg2+ was performed by hyphenated system combining ethylation and/or hydride generation on-line with Cryogenic trapping, gas chromatography and atomic fluorescence spectrometry. Validation of methods was performed using a certified sediment and biological reference material. Results of organotin species cannot allow to establish any significant difference between the seasonal levels of contamination. The high values found in the South East of the lagoon and specially in the region of Menzel Bouguiba can be related to the intense industrial activities in this area. The predominance of butyl- and phenyltins comes probably from antifouling paints on boats and piers. Indeed tributyl- and triphenyltins contained in these paints are directly released into the environment. Results show the predominance of butyltin compounds for all stations, and of monosubstituted compounds during summer. Among all the organotins, the trisubstituted ones and specially TBT have quite high concentrations, which are widely due to releasing from antifouling paints, since an important maritime traffic exists in the lagoon. The increasing of mono- and disubstituted compounds is attributed to the biodegradation phenomenon, which conducts to the successive desalkylation or desarylation of all the organotins since the concentrations of monoorganotins are slowly increasing

  9. UK‧37 temperature estimates from Eemian marine sediments in the southern coast of Hainan Island, tropical China

    Science.gov (United States)

    Wang, Mengyuan; Zheng, Zhuo; Huang, Kangyou; Zong, Yongqiang; Liu, Zhonghui; Peng, Zhuolun; Shi, Suhua

    2016-09-01

    This study concerns high-resolution sea surface temperature (SST) changes for the Eemian interglacial period reconstructed from the southern coast of Hainan Island, China. The lower marine unit in the sediment core is composed of monotonous mud (31 m thick), dated to be from the Eemian interglacial period or lower part of marine isotope stage 5 (MIS 5), determined by optically stimulated luminescence (OSL). The high sedimentation rate and the richness of organic matter and marine fossils provide good opportunity for the study of palaeo-environments in the northern margin of the South China Sea (SCS). Sediment grain-size, foraminifer, sediment color index and long-chain alkenone were used to reveal the near-shore sedimentary environments and temperature at millennial-scale. Specifically, a high-resolution UK‧37-SST record was reconstructed for the Eemian interglacial period. The new evidence in northwestern margin of SCS shows that the maximum value of SST during the Eemian interglacial is approximately 29 °C and the lowest is 26.5 °C. The trend of decreasing SST from 29 °C throughout the marine sequence is consistent with the variations in sediment grain size, reflecting the cooling trend of SST and sea-level lowering tendency during the last interglacial period. This new Eemian SST result agrees with other records in the region of SCS, showing a coherent descending trend, but spatial heterogeneity exists in timing and amplitude. The insolation changes might be the main force for initiating the SST evolution during the penultimate interglacial period.

  10. Management of Reflex Anoxic Seizures

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2013-10-01

    Full Text Available Investigators at the Roald Dahl EEG Unit, Alder Hey Children’s NHS Foundation, Liverpool, UK, review the definition, pathophysiology, clinical presentation, and management of reflex anoxic seizures (RAS in children.

  11. Glacial marine sediments from the Antarctic Peninsula: A record of climate change and glacial fluctuations during the late holocene

    International Nuclear Information System (INIS)

    Physical oceanographic measurements (211 CTDT casts) and bottom sediment samples (>104) provide the data base for the following conclusions. Subpolar glacial regimes in the South Shetland Islands are dominated by extensive surface melting, elevated equilibrium lines (ELA) and efficient conduction of surface meltwater to the terminus of tidewater and terrestrial glaciers. These conditions control sedimentary processes in the marine realm by the efficient and widespread dispersal of suspended sediment by overflow plumes. Terrigenous facies, therefore, dominate throughout the fjord system. The transition to polar conditions within glaciers along the Danco Coast and Palmer Archipelago is characterized by lower ELA (near sea level), limited surface melting and dynamic sea ice conditions. Basal melt processes appear to dominate, especially where subglacial marine cavities exist beneath glacial termini. Most terrigenous sediment is transported by ice-rafting or by cold, mid-water plumes, which spread horizontally until restricted by bathymetric features. Biogenic (diatom) muds and ice-rafted debris dominate sedimentation in outer bay settings; the former is enhanced by warmer temperatures, increased sunlight, and minimal disturbance of surface layers within the fjords. These facies transitions are well constrained statistically by regression analyses of textural and compositional variations with respect to distance from sediment sources (glacial termini). Correlation trends within individual ice drainage systems can be applied to marine sediment cores which contain a record spanning approximately the last 3,000 years (based upon accelerator 14C and 210Pb chronologies). A period of enhanced terrigenous (surface meltwater) input following more extensive glacier ice is documented in Hughes Bay on the northern Danco Coast

  12. Experimental and in situ investigations on americium, curium and plutonium behaviour in marine benthic species: transfer from water or sediments

    International Nuclear Information System (INIS)

    The tranfer of transuranic elements -americium, curium and plutonium- from the sediments containing them to some marine benthic species (endofauna and epifauna) was studied with a twofold approach - laboratory and in-situ investigation. The experimental investigations, divided into three parts, made it possible to specify concentration factors (F.C.), transfer factors (F.T.) and to understand the process involved for 5 benthic species. The result were refined by an in-situ study that brought new data on the marine distribution of the transuranic elements released by the La Hague plant. Finally, the localization of americium and plutonium in the tissues and cells of these species was determined by autoradiography

  13. The linkage between marine sediment records and changes in Holocene Saharan landscape: simulating the dust cycle

    Science.gov (United States)

    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 ka to 5.5 ka ago (deMenocal et al., 2000; McGee et al., 2013). 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. We present simulation results from a recent sensitivity study, where we demonstrate for the first time the direct link between dust accumulation in marine cores and changes in Saharan land surface during the Holocene. We have simulated timeslices of he 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. We prescribe mid-Holocene vegetation cover based on a vegetation reconstruction from pollen data (Hoelzmann et al., 1998) and mid-Holocene lake surface area is determined using a water routing and storage model (Tegen et al., 2002). 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 variation in dust accumulation in marine cores is likely related to a transition of the Saharan landscape during the Holocene and not due to changes in atmospheric or ocean conditions alone. Reference: deMenocal, P., Ortiz, J., Guilderson, T., Adkins, J., Sarnthein, M., Baker, L., and Yarusinsky, M.: Abrupt onset and termination of the African Humid Period:: rapid climate responses to gradual insolation forcing, Quaternary Science Reviews, 19, 347-361, 2000. Hoelzmann, P., Jolly, D., Harrison, S. P., Laarif, F

  14. Response of marine sedimentation to upper Holocene climate variability in Maxwell Bay, King George Island, West Antarctic Peninsula

    Science.gov (United States)

    Wittenberg, Nina; Hass, Christian; Kuhn, Gerhard

    2013-04-01

    The Western Antarctic Peninsula experiences a temperature increase that is higher than in other parts of Antarctica. Within the last 50 years the tidewater glaciers in the tributary fjords of Maxwell Bay (King George Island) have retreated landwards with increasing speed. Meltwaters mobilize fine-grained sediments and transport those in plumes out of the coves into Maxwell Bay. Our hypothesis is that meltwater sediments characterize warmer climate periods of the Holocene. Marine sediment cores recovered along a profile of the eastern slope of Maxwell Bay were studied. The cores were taken in high-accumulation areas at the entrances of Collins Harbor, Marian and Potter coves. We measured the grain-size distribution in 1-cm steps in each core with a Laser diffraction particle analyzer (range 0.04-2500 µm) in order to resolve shifts in grain size compositions in very high resolution. We undertook different approaches for reliable age determination of the sediments. Since marine biogenic carbonate suitable for radiocarbon age determination is sparse, radiocarbon dating of the extracted humic acid fraction of the bulk sediment was included. Unfortunately, these age determinations turned out to be not reliable, likely because they are overprinted by an unknown older radiocarbon source. Preliminary results suggest that the cores cover approximately the last 2000 years. The magnetic susceptibility (MS) parameter fluctuates throughout the cores. It is negatively correlated to the amount of total organic carbon (TOC) and biogenic opal, suggesting dilution of the MS signal through higher input of organic material. Together with the bathymetry data, sub-bottom profiles reveal information on the interior of the topography and the geometry of the deposited sediments. The profiles obtained in Potter Cove show almost no sediment penetration suggesting either a very thin sediment cover and/or highly reworked unsorted sediments. The sub-bottom profiles from Maxwell Bay penetrate

  15. Bioreactor-based bioremediation of hydrocarbon-polluted Niger Delta marine sediment, Nigeria.

    Science.gov (United States)

    Chikere, Chioma Blaise; Chikere, Blaise Ositadinma; Okpokwasili, Gideon Chijioke

    2012-03-01

    Crude oil-polluted marine sediment from Bonny River loading jetty Port Harcourt, Nigeria was treated in seven 2.5 l stirred-tank bioreactors designated BNPK, BNK5, BPD, BNO(3), BUNa, BAUT, and BUK over a 56-day period. Five bioreactors were biostimulated with either K(2)HPO(4), NH(4)NO(3), (NH(4))(2)SO(4), NPK, urea or poultry droppings while unamended (BUNa) and heat-killed (BAUT) treatments were controls. For each bioreactor, 1 kg (wet weight) sediment amended with 1 l seawater were spiked with 20 ml and 20 mg of crude oil and anthracene which gave a total petroleum hydrocarbons (TPH) range of 106.4-116 ppm on day 0. Polycyclic aromatic hydrocarbons (PAH) in all spiked sediment slurry ranged from 96.6 to 104.4 ppm. TPH in each treatment was ≤14.9 ppm while PAH was ≤6.8 ppm by day 56. Treatment BNO(3) recorded highest heterotrophic bacterial count (9.8 × 10(8) cfu/g) and hydrocarbon utilizers (1.15 × 10(8) cfu/g). By day 56, the percentages of biodegradation of PAHs, as measured with GC-FID were BNK5 (97.93%), BNPK (98.38%), BUK (98.82%), BUNa (98.13%), BAUT (93.08%), BPD (98.92%), and BNO(3) (98.02%). BPD gave the highest degradation rate for PAH. TPH degradation rates were as follows: BNK5 (94.50%), BNPK (94.77%), BUK (94.10%), BUNa (94.77%), BAUT (75.04%), BPD (95.35%), BNO(3) (95.54%). Fifty-six hydrocarbon utilizing bacterial isolates obtained were Micrococcus spp. 5 (9.62%), Staphylococcus spp. 3 (5.78%), Pseudomonas spp. 7 (13.46%), Citrobacter sp. 1 (1.92%), Klebsiella sp. 1 (1.92%), Corynebacterium spp. 5 (9.62%), Bacillus spp. 5 (9.62%), Rhodococcus spp. 7 (13.46%), Alcanivorax spp. 7 (13.46%), Alcaligenes sp. 1 (1.92%), Serratia spp. 2 (3.85%), Arthrobacter spp. 7 (13.46%), Nocardia spp. 2 (3.85%), Flavobacterium sp. 1 (1.92%), Escherichia sp. 1 (1.92%), Acinetobacter sp. 1 (1.92%), Proteus sp. 1 (1.92%) and unidentified bacteria 10 (17%). These results indicate that the marine sediment investigated is amenable to bioreactor

  16. Distribution and generic composition of culturable marine actinomycetes from the sediments of Indian continental slope of Bay of Bengal

    Science.gov (United States)

    Das, Surajit; Lyla, P. S.; Ajmal Khan, S.

    2008-05-01

    Actinomycetes population from continental slope sediment of the Bay of Bengal was studied. Samples were collected during two voyages of FORV Sagar Sampada in 2004 (May-June) and 2005 (July) respectively from 11 transects (each transect had ca. 200 m, 500 m, and 1 000 m depth stations). The physicochemical parameters of overlying water, and sediment samples were also recorded. The actinomycete population ranged from 5.17 to 51.94 CFU/g dry sediment weight and 9.38 to 45.22 CFU/g dry sediment weight during the two cruises respectively. No actinomycete colony was isolated from stations in 1 000 m depth. Two-way analysis of variance showed significant variation among stations (ANOVA two-way, P0.05). Three actinomycetes genera were identified. Streptomyces was found to be the dominating one in both the cruises, followed by Micromonospora, and Actinomyces. The spore of Streptomyces isolates showed the abundance in spiral spore chain. Spore surface was smooth. Multiple regression analysis revealed that the influencing physico-chemical factors were sediment pH, sediment temperature, TOC, porosity, salinity, and pressure. The media used in the present study was prepared with seawater. Thus, they may represent an autochthonous marine flora and deny the theory of land runoff carriage into the sea for adaptation to the salinity of the seawater and sediments.

  17. Magnetostratigraphy of Lutetian marine sediments in the External Sierras (Southern Pyrenees)

    Science.gov (United States)

    Rodriguez-Pinto, A.; Pueyo, E. L.; Barnolas, A.; Pocovi, A.; Gil-Pena, I.; Villain, J. J.; Mochales, T.; Samso, J. M.

    2007-05-01

    Magnetostratigraphy has been extensively applied in the southern Pyrenees (Spain). At the moment there are more than 50 km of series most of them in continental and transitional facies and only a few in marine sediments. Seeing that Lutetian age has received very little attention and Ypresian - Lutetian transit in marine series has been rarely studied, in this work we present a composite Lutetian magnetostratigraphic study made of three sections of carbonate platform facies. The composite section has been calibrated with the available biostratigraphic studies (mostly benthonic faunas). The three sections are located in hanging wall of the Southwestern Pyrenean sole thrust (External Sierras). The SIV section (260 m and 105 samples), is located in the southeastern limb of the Balzez anticline, and comprises lower Guara Formation. The BZ profile (600 m and 285 samples) is located in the northwestern flank and cuts a progressive unconformity within the Guara formation. The ISU section (550 m and 237 samples) is located along the Isuela valley immediately south of the well-known Pico del Aguila anticline. In total more than 600 standard cores were sampled every 2 - 3 meters of section. Paleomagnetic analyses were conducted in the University of Burgos paleomagnetic laboratory. Detailed stepwise thermal demagnetization (every 25-50°C) and some AF demagnetizations were able to unravel the NRM components. IRM essays and the thermal demagnetization of three components IRM allowed controlling the magnetic mineralogy. A 2G magnetometer, an ASC TD-SC oven and a M2T-1 pulse magnetizer were utilized. Only one paleomagnetic component has been characterized between 200° - 250° and 450°C - 575°. This component represents a primary record of the Eocene magnetic field because it presents two antipodal directions and passes the fold test (Balzez data). Comparison with the global polarity time scale (GPTS) displays the following correlation; chrons C21 and C20 were unambiguously

  18. Variations of marine pore water salinity and chlorinity in Gulf of Alaska sediments (IODP Expedition 341)

    Science.gov (United States)

    März, Christian; Mix, Alan C.; McClymont, Erin; Nakamura, Atsunori; Berbel, Glaucia; Gulick, Sean; Jaeger, John; Schneider (LeVay), Leah

    2014-05-01

    Pore waters of marine sediments usually have salinities and chlorinities similar to the overlying sea water, ranging around 34-35 psu (Practical Salinity Units) and around 550 mM Cl-, respectively. This is because these parameters are conservative in the sense that they do not significantly participate in biogeochemical cycles. However, pore water studies carried out in the frame of the International Ocean Discovery Program (IODP) and its predecessors have shown that salinities and chlorinities of marine pore waters can substantially deviate from the modern bottom water composition in a number of environmental settings, and various processes have been suggested to explain these phenomena. Also during the recent IODP Expedition 341 that drilled five sites in the Gulf of Alaska (Northeast Pacific Ocean) from the deep Surveyor Fan across the continental slope to the glaciomarine shelf deposits, several occurrences of pore waters with salinities and chlorinities significantly different from respective bottom waters were encountered during shipboard analyses. At the pelagic Sites U1417 and U1418 (~4,200 and ~3,700 m water depth, respectively), salinity and chlorinity maxima occur around 20-50 m sediment depth, but values gradually decrease with increasing drilling depths (down to 30 psu in ~600 m sediment depth). While the pore water freshening at depth is most likely an effect of clay mineral dehydration due to increasing burial depth, the shallow salinity and chlorinity maxima are interpreted as relicts of more saline bottom waters that existed in the North Pacific during the Last Glacial Maximum (Adkins et al., 2002). In contrast, the glaciomarine slope and shelf deposits at Site U1419 to U1421 (~200 to 1,000 m water depth) are characterised by unexpectedly low salinitiy and chlorinity values (as low as 16 psu and 295 mM Cl-, respectively) already in very shallow sediment depths (~10 m), and their records do not show systematic trends with sediment depth. Freshening

  19. Sub-MIlankovitch millennial and decadal cyclicity in Middle Eocene deep-marine laminated sediments, Ainsa Basin, Spanish Pyrenees

    Science.gov (United States)

    Scotchman, J. I.; Pickering, K. T.; Robinson, S. A.

    2010-12-01

    James I. Scotchman1, Kevin T. Pickering1 & Stuart A. Robinson1 1Department of Earth Sciences, UCL (University College London), Gower Street, London, WC1E 6BT, U.K. Climate variability on the scale of millennia has become conspicuous within Quaternary records with far fewer such records existing within the pre-Pleistocene geological record. We identify millennial and decadal cyclicity in deep-marine siliciclastic (turbiditic and hemipelagic) sediments from a core in the middle Eocene Ainsa Basin, Spanish Pyrenees. Outcrop spectral gamma-ray data from laterally adjacent and age-equivalent strata to the core, together with a re-analysis of bioturbation data from the core, identifies the three main Milankovitch orbital periods. From this data, we derive a robust sediment accumulation rate for these sediments of 27.5 cm/kyr. Spectral analysis of data from high-resolution multi-element XRF scanning of a ~10 m-thick stratigraphic interval of fine-grained laminated sediments reveals the presence of various high-frequency cycles mainly above the 99% confidence level. Applying our derived sediment accumulation rate yields sub-Milankovitch millennial-scale cycles (~5,400, ~2,800, and ~1,000 yr) and decadal (~90, ~50, and ~30 yr) cycles split between allogenic and authigenic deposition. These cycles are manifest in the core as grain-size variations. The ~5,400 and ~2,800 yr cycles, recorded by elemental (Al, K, Ca and Fe) and element/Al ratios (Si/Al, Ca/Al and Zr/Al) are interpreted as representing climatically-driven variation in sediment supply to the deep-marine Ainsa basin. Higher-frequency decadal cycles are coincident with well-known Gleissberg solar cycles or possible multiples of the 11-year Schwabe cycle although how these cycles are expressed within these sediments remains unclear.

  20. Rare earth elements determination and distribution patterns in sediments of a polluted marine environment by instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    Results obtained from the analysis of sediment core samples taken from a fairly polluted marine environment were analyzed for the REE contents to determine the concentrations of La, Ce, Sm, Eu, Tb, Dy and Yb using instrumental neutron activation analysis. Core samples were divided into strata of between 2 to 3 cm intervals and prepared in the powdered form before irradiating them in a neutron flux of about 5.0 x 1012 n x cm-2 x s-1 in a Triga Mark II reactor. Down-core concentration profiles of La, Ce, Sm, Eu, Tb, Dy and Yb in 3 core sediments from three sites are obtained. The shale-normalized REE pattern from each site was examined and later used to explain the history of sedimentation by natural processes such as shoreline erosion and weathering products deposited on the seabed and furnishing some baseline data and/or pollution trend occurring within the study area. The shale-normalized REE patterns also showed that LREE in the sediment samples exhibit enrichment relative to HREE particularly, La and Sm showing enrichment compared to the ratios in shale. REE concentrations of 124 μg/g at the surface of sediment collected at two of the three sites were found to decrease to 58 and 95 μg/g, respectively. This was of particular interest when it is used to explain the anomalies occurring in the marine sediment as a result of geochemical processes over a long period of time. Changes in concentrations from surface to bottom of the sediments ratioed to Sm concentrations and the correlation between concentrations of Sm and these elements were also investigated and correlation coefficients were calculated for all REEs and sites. Validation of the method used was done using a Soil-7 SRM. (author)

  1. Defining seascapes for marine unconsolidated shelf sediments in an eastern boundary upwelling region: The southern Benguela as a case study

    Science.gov (United States)

    Karenyi, Natasha; Sink, Kerry; Nel, Ronel

    2016-02-01

    Marine unconsolidated sediment habitats, the largest benthic ecosystem, are considered physically controlled ecosystems driven by a number of local physical processes. Depth and sediment type are recognised key drivers of these ecosystems. Seascape (i.e., marine landscape) habitat classifications are based solely on consistent geophysical features and provide an opportunity to define unconsolidated sediment habitats based on processes which may vary in distribution through space and time. This paper aimed to classify unconsolidated sediment seascapes and explore their diversity in an eastern boundary upwelling region at the macro-scale, using the South African west coast as a case study. Physical variables such as sediment grain size, depth and upwelling-related variables (i.e., maximum chlorophyll concentration, austral summer bottom oxygen concentration and sediment organic carbon content) were included in the analyses. These variables were directly measured through sampling, or collated from existing databases and the literature. These data were analysed using multivariate Cluster, Principal Components Ordination and SIMPER analyses (in PRIMER 6 + with PERMANOVA add-in package). There were four main findings; (i) eight seascapes were identified for the South African west coast based on depth, slope, sediment grain size and upwelling-related variables, (ii) three depth zones were distinguished (inner, middle and outer shelf), (iii) seascape diversity in the inner and middle shelves was greater than the outer shelf, and (iv) upwelling-related variables were responsible for the habitat diversity in both inner and middle shelves. This research demonstrates that the inclusion of productivity and its related variables, such as hypoxia and sedimentary organic carbon, in seascape classifications will enhance the ability to distinguish seascapes on continental shelves, where productivity is most variable.

  2. Simultaneous enumeration of diatom, protozoa and meiobenthos from marine sediments using Ludox-QPS method

    Institute of Scientific and Technical Information of China (English)

    DU Yongfen; XU Kuidong; LEI Yanli

    2009-01-01

    The Ludox-QPS method is a newly developed technique, which combines the Ludox HS 40 density centrifugation and quantitative protargol stain, to enumerate marine ciliates with good taxonomic resolution. We tested the method for simultaneous enumeration of diatoms, protozoa and meiobenthos and compared its extraction efficiency for meiobenthos with that of the routine Ludox-TM centrifugation and a modified protocol using Ludox HS 40. We conducted the evaluation with a sample size of 8.3 ml each from sandy, muddy-sand and muddy sediments collected from the intertidal area of the Yellow Sea in summer 2006 and spring 2007. The Ludox-QPS method not only produced high extraction efficiencies of 97±1.3% for diatoms and 97.6±0.8% for ciliates, indicating a reliable enumeration for eukaryotic microbenthos, but also produced excellent extraction efficiencies of on average 97.3% for total meiobenthos, 97.9% for nematodes and 97.8% for copepods from sands, muddy sands and mud. By contrast, the routine Ludox-TM centrifugation obtained only about 74% of total meiobenthos abundance with one extraction cycle, and the modified Ludox HS 40 centrifugation yielded on average 93% of total meiobenthos: 89.4±2.0% from sands, 93±4.1% from muddy sands and 97.1±3.0% from mud. Apart from the sediment type, sample volume was another important factor affecting the extraction efficiency for meiobenthos. The extraction rate was increased to about 96.4% when using the same modified Ludox centrifugation for a 4 ml sediment sample. Besides the excellent extraction efficiency, the Ludox-QPS method obtained higher abundances of meiobenthos, in particular nematodes, than the routine Ludox centrifugation, which frequently resulted in an uncertain loss of small meiobenthos during the sieving process. Statistical analyses demonstrated that there were no significant differences between the meiobenthos communities revealed by the Ludox-QPS method and the modified Ludox HS 40 centrifugation, showing the

  3. Nuclear magnetic resonance properties of marine sediments from the Nankai Trough

    Science.gov (United States)

    Thomas, B.; Daigle, H.

    2013-12-01

    We performed nuclear magnetic resonance (NMR) measurements of longitudinal (T1) and transverse (T2) relaxation times on samples from Integrated Ocean Drilling Program (IODP) Expedition 333 Sites C0011, C0012, and C0018. We compared these measurements with independent measurements of pore size distribution and permeability to develop methods for determining pore structure and permeability directly from NMR data. Geometric means of the T1 and T2 distributions ranged from 0.87 to 7.95 and 0.45 to 6.04 ms, respectively. We compared the T1 and T2 distributions to pore size distributions determined from Mercury Injection Capillary Pressure (MICP) measurements to determine the longitudinal and transverse surface relaxivities, which link relaxation time distribution to pore size. Longitudinal and transverse surface relaxivities ranged generally from 12.2 to 21.8 and 17.51 to 44.04 μm/s, respectively, with one outlier from the sediment-basement interface at Site C0012 having relaxivity values of 256.9 and 335.6 μm/s. Larger surface relaxivities were found to correlate with higher iron content in the sediments. The ratio of the geometric means of the relaxation time distributions (T1LM/T2LM) and the ratio of the surface relaxivities (ρ2/ρ1) both increase linearly with magnetic susceptibility, but magnetic susceptibility displays no relationship with the individual relaxation times or surface relaxivities. We additionally compared T2 values to measured permeabilities using the Schlumberger-Doll Research (SDR) equation. SDR equation coefficient A values were generally in the range of 7x10-18 to 8x10-17 m2/ms2 (0.007 to 0.080 mD/ms2). A is inversely correlated with clay-size particle fraction and specific surface, which suggests that A is mainly controlled by changes in pore or grain structure rather than mineralogy. Our results provide constraints for NMR determinations of pore size and permeability in marine sediments and illustrate the links between NMR properties

  4. Laboratory scale electrokinetic remediation and geophysical monitoring of metal-contaminated marine sediments

    Science.gov (United States)

    Masi, Matteo; Pazzi, Veronica; Losito, Gabriella

    2013-04-01

    Electrokinetic remediation is an emerging technology that can be used to remove contaminants from soils and sediments. This technique relies on the application of a low-intensity electric field to extract heavy metals, radionuclides and some organic compounds. When the electric field is applied three main transport processes occur in the porous medium: electromigration, electroosmosis and electrophoresis. Monitoring of electrokinetic processes in laboratory and field is usually conducted by means of point measurements and by collecting samples from discrete locations. Geophysical methods can be very effective in obtaining high spatial and temporal resolution mapping for an adequate control of the electrokinetic processes. This study investigates the suitability of electrokinetic remediation for extracting heavy metals from dredged marine sediments and the possibility of using geophysical methods to monitor the remediation process. Among the geophysical methods, the spectral induced polarization technique was selected because of its capability to provide valuable information about the physico-chemical characteristics of the porous medium. Electrokinetic remediation experiments in laboratory scale were made under different operating conditions, obtained by varying the strength of the applied electric field and the type of conditioning agent used at the electrode compartments in each experiment. Tap water, 0.1M citric acid and 0.1M ethylenediamine tetraacetic acid (EDTA) solutions were used respectively as processing fluids. Metal removal was relevant when EDTA was used as conditioning agent and the electric potential was increased, as these two factors promoted the electroosmotic flow which is considered to be the key transport mechanism. The removal efficiencies ranged from 9.5% to 27% depending on the contaminant concerned. These percentages are likely to be raised by a further increase of the applied electric field. Furthermore, spectral induced polarization

  5. Composite cement mortars based on marine sediments and oyster shell powder

    Directory of Open Access Journals (Sweden)

    Ez-zaki, H.

    2016-03-01

    Full Text Available Additions of dredged marine sediments and oyster shell powder (OS as cement substitute materials in mortars are examined by several techniques. The sediments have high water and chloride contents and calcite, quartz, illite and kaolinite as principal minerals. The OS powders are entirely composed of calcium carbonate and traces of other impurities. Four mixtures of treated sediments and OS powders at 650 °C and 850 °C are added to Portland cement at 8%, 16% and 33% by weight. The hydration of composite pastes is followed by calorimetric tests, the porosity accessible to water, the bulk density, the permeability to gas, the compressive strength and the accelerated carbonation resistance are measured. In general, the increase of addition amounts reduced the performance of mortars. However, a reduction of gas permeability was observed when the addition was up to 33%. Around 16% of addition, the compressive strength and carbonation resistance were improved.En este trabajo se ha valorado la sustitución de cemento en morteros por sedimentos marinos dragados y polvo de concha de ostra (OS. Los sedimentos tienen altos contenidos de agua, cloruros, calcita, cuarzo, illita y caolinita como minerales principales. Los polvos OS están compuestos de carbonato cálcico y trazas de otras impurezas. Se añadieron a un cemento Portland, cuatro mezclas de los sedimentos y polvos de OS tratados a 650 °C y 850 °C en proporciones del 8%, 16% y 33% en peso. La hidratación de pastas se estudió a través de calorimetría. Se estudió además la porosidad accesible al agua, densidad aparente, permeabilidad al gas, resistencia a compresión y carbonatación acelerada. En general, un aumento en la adición produjo una reducción del rendimiento de los morteros. Se observó, sin embargo, una reducción de la permeabilidad a los gases con porcentajes de adición de hasta el 33%. Con valores del 16% de sustitución, mejoraron las resistencias mecánicas y la

  6. Biogenic habitat transitions influence facilitation in a marine soft-sediment ecosystem.

    Science.gov (United States)

    Lohrer, Andrew M; Rodil, Iván F; Townsend, Michael; Chiaroni, Luca D; Hewitt, Judi E; Thrush, Simon F

    2013-01-01

    Habitats are often defined by the presence of key species and biogenic features. However, the ecological consequences of interactions among distinct habitat-forming species in transition zones where their habitats overlap remain poorly understood. We investigated transition zone interactions by conducting experiments at three locations in Mahurangi Harbour, New Zealand, where the abundance of two habitat-forming marine species naturally varied. The two key species differed in form and function: One was a sessile suspension-feeding bivalve that protruded from the sediment (Atrina zelandica; Pinnidae); the other was a mobile infaunal urchin that bioturbated sediment (Echinocardium cordatum; Spatangoida). The experimental treatments established at each site reflected the natural densities of the species across sites (Atrina only, Echinocardium only, Atrina and Echinocardium together, and plots with neither species present). We identified the individual and combined effects of the two key species on sediment characteristics and co-occurring macrofauna. After five months, we documented significant treatment effects, including the highest abundance of co-occurring macrofauna in the Atrina-only treatments. However, the facilitation of macrofauna by Atrina (relative to removal treatments) was entirely negated in the presence of Echinocardium at densities >10 individuals/m2. The transitional areas in Mahurangi Harbour composed of co-occurring Atrina and Echinocardium are currently widespread and are probably more common now than monospecific patches of either individual species, due to the thinning of dense Atrina patches into sparser mixed zones during the last 10-15 years. Thus, although some ecologists avoid ecotones and habitat edges when designing experiments, suspecting that it will skew the extrapolation of results, this study increased our understanding of benthic community dynamics across larger proportions of the seascape and provided insights into temporal

  7. Alkenone paleothermometry: Biological lessons from marine sediment records off western South America

    Science.gov (United States)

    Prahl, Fredrick G.; Mix, Alan C.; Sparrow, Margaret A.

    2006-01-01

    An empirical global core-top calibration that relates the alkenone unsaturation index U37K' to mean annual SST (maSST) is statistically the same as that defined for a subarctic Pacific strain of Emiliania huxleyi (CCMP1742) grown exponentially in batch culture under isothermal conditions. Although both equations have been applied widely for paleoSST reconstruction, uncertainty still stems from two key ecological factors: variability in the details of biosynthesis among genetically distinct alkenone-producing strains, and impacts of non-thermal physiological growth factors on U37K'. New batch culture experiments with CCMP1742 here reveal that U37K' diverge systematically from the core-top calibration in response to nutrient depletion and light deprivation, two physiological stresses experienced by phytoplankton populations in the real ocean. Other aspects of alkenone/alkenoate composition also respond to these stresses and may serve as signatures of such effects, providing an opportunity to detect, understand, and potentially correct for such impacts on the geologic record. A test case documents that sediments from the Southeast Pacific display the alkenone/alkenoate compositional signature characteristic of cells physiologically stressed by light deprivation. Such an observation could be explained if marine snow provided a major vector of sedimentation for these biomarkers. Late Pleistocene U37K' records in the Southeast Pacific yield plausible paleotemperature histories of ice-age cooling, but ice-age alkenone/alkenoate signatures fall outside the range of modern calibration samples of similar U37K'. They better match core-top samples deposited beneath waters characterized by much cooler maSST, suggesting key features of ice-age ecology for alkenone-producing haptophytes were different from today, and that the U37K' index taken alone may misgauge the total range of ice-age cooling at these locations. Analysis of the full spectrum of alkenone/alkenoate compositions

  8. Integrated Assessment of Heavy Metal Pollution in the Surface Sediments of the Laizhou Bay and the Coastal Waters of the Zhangzi Island, China: Comparison among Typical Marine Sediment Quality Indices

    OpenAIRE

    Zhuang, Wen; Gao, Xuelu

    2014-01-01

    The total concentrations and chemical forms of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in the surface sediments of the Laizhou Bay and the surrounding marine area of the Zhangzi Island (hereafter referred to as Zhangzi Island for short) were obtained and multiple indices and guidelines were applied to assess their contamination and ecological risks. The sedimentary conditions were fine in both of the two studied areas according to the marine sediment quality of China. Whereas the probable ef...

  9. Northern Gulf Littoral Initiative (NGLI), Geology and Physical Properties of Marine Sediments in the N.E. Gulf of Mexico: Data Report

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Northern Gulf Littoral Initiative (NGLI), Geology and Physical Properties of Marine Sediments in the N.E. gulf of Mexico: Data Report, was produced by the U.S....

  10. A marine microbial consortium apparently mediating anaerobic oxidation of methane

    DEFF Research Database (Denmark)

    Boetius, A.; Ravenschlag, K.; Schubert, CJ;

    2000-01-01

    A large fraction of globally produced methane is converted to CO2 by anaerobic oxidation in marine sediments(1). Strong geochemical evidence for net methane consumption in anoxic sediments is based on methane profiles(2), radiotracer experiments(3) and stable carbon isotope data(4). But the elusive...... evidence for a structured consortium of archaea and sulphate-reducing bacteria, which we identified by fluorescence in situ hybridization using specific 16S rRNA-targeted oligonucleotide probes. In this example of a structured archaeal-bacterial symbiosis, the archaea grow in dense aggregates of about 100...

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

    Science.gov (United States)

    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 (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 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 sediment nor were the bottom waters persistently anoxic. In addition, the presence of thin lags and sharp-based beds suggests that the seafloor was being episodically reworked during deposition. These fabrics indicate that conditions in the water columns and at the seafloors while these rocks were being deposited were very dynamic, and episodic fluxes of high concentrations of organic carbon to the seafloor, during phytoplankton blooms, likely enhanced preservation of organic carbon. Copyright ?? 2010, SEPM (Society for Sedimentary Geology).

  12. Transfer in Marine Sediments of the Naturally Occurring Plasmid pRAS1 Encoding Multiple Antibiotic Resistance

    OpenAIRE

    Sandaa, Ruth-Anne; Enger, Øivind

    1994-01-01

    The results of microcosm experiments performed with the fish-pathogenic bacterium Aeromonas salmonicida acting as a donor showed that promiscuous plasmid pRAS1, which encodes tetracycline resistance, is transferred at a high frequency in marine sediments even in the absence of a selective factor. The presence of oxytetracycline resulted in an increase in the transfer frequency compared with that of a microcosm to which no selective factor was added. Transfer frequencies of 3.4 × 10-1 transcon...

  13. Application of microwave energy to speed up the alkaline extraction of humic and fulvic acids from marine sediments

    International Nuclear Information System (INIS)

    The feasibility of microwave energy to speed up the alkaline extraction of humic substances (humic acid, HA, and fulvic acid, FA) from marine sediments has been checked. Extractions were performed by using 20 mL of sodium hydroxide at 0.1 M (two repeated extractions) after an ultrasound-assisted acid pre-treatment of samples to remove the carbonate fraction (ultrasound power at 17 kHz, 10 mL of 6.0 M hydrochloric acid for 15 min). After separation of HA and FA fractions by acidifying with 6 M HCl, the FA fraction (supernatant) was purified by passing the solution through a column of Amberlite XAD-8. Both HA and FA extracts were measured by UV-visible spectrophotometry. All variables affecting the extraction process (sodium hydroxide concentration and volume, ramp and hold times, temperature and number of repeated extractions) have been screened by using a Plackett-Burman design (PBD) as multivariate approach. The variables temperature and number of repeated extractions were the most significant factors (P = 95%) affecting the extraction of both FA and HA from marine sediments. These two variables have led optimum values of 150 deg. C and two repeated extractions. The developed method has been found precise (R.S.D.s of 9% for HA and 12% for FA, for 11 determinations) and its results were comparable in terms of elemental (C, H and N) composition to those obtained after applying methods based on mechanical stirring and ultrasounds assisting. However, higher HA and FA concentrations than those obtained after conventional stirring and ultrasound irradiation were obtained when applying microwave energy. This means a higher efficiency of microwave energy than ultrasounds or mechanical stirring to extract HA and FA fractions from marine sediments. The method was finally applied to different surface marine sediments from the Ria de Arousa estuary

  14. Depositional environment, ichnological features and oxygenation of Permian to earliest Triassic marine sediments in central Spitsbergen, Svalbard

    OpenAIRE

    Uchman, Alfred; Hanken, Nils-Martin; Nielsen, Jesper Kresten; Piasecki, Stefan; Grundvåg, Sten-Andreas

    2016-01-01

    Late Early Permian–lowermost Triassic carbonate, siliceous (spiculites) and clastic marine sediments in the Marmierfjellet area (Isfjorden, central Spitsbergen) contain a relatively diverse and abundant trace fossil assemblage providing important information about the depositional processes. The Vøringen Member (Late Artinskian–Kungurian) of the Kapp Starostin Formation (Late Artinskian–? Changhsingian) contains trace fossils (Nereites, Phycosiphon, Zoophycos and Arenicolites—common in tempes...

  15. Comparison of the sample collection strategies for the investigation of pollution stage of some heavy metals in marine sediments

    OpenAIRE

    Baysal A.; Manasir Oz T.; Akman S.

    2014-01-01

    In this work, sampling collection strategies were compared for the determination of some heavy metals (Pb, Cr, Ni) and investigate their effects on the marine pollution. The sampling area is a natural bay using as a shipbuilding industries for three decades especially. To determine the permanent heavy metal pollution in this area, the sediment samples were taken different strategies; i) the bay were divided square pieces which is 200 m length, and the samples were taken this distance (total 7...

  16. Release of Ni from birnessite during transformation of birnessite to todorokite: Implications for Ni cycling in marine sediments

    Science.gov (United States)

    Atkins, Amy L.; Shaw, Samuel; Peacock, Caroline L.

    2016-09-01

    The phyllomanganate birnessite is the main Mn-bearing phase in oxic marine sediments where it exerts a primary control on the concentration of micronutrient trace metals in seawater. However, during sediment diagenesis and under mild hydrothermal conditions birnessite transforms into the tectomanganate todorokite. We have recently shown that the transformation of birnessite to todorokite proceeds via a four-stage nucleation and growth mechanism, 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 (Atkins et al., 2014). Here we determine the fate and mobility of Ni sorbed by birnessite during this transformation process. Specifically, in our recent work we predict that the presence of Ni within the phyllomanganate matrix will disrupt the formation of todorokite primary particles. As such, contrary to current understanding, we suggest that Ni sorbed by birnessite will slow the transformation of birnessite to todorokite and/or be released to marine porewaters during sediment diagenesis. Here we transform a synthetic, poorly crystalline, Ni-sorbed (∼1 wt% Ni) hexagonal birnessite, analogous to marine birnessite, into todorokite under a mild reflux procedure, developed to mimic marine diagenesis and mild hydrothermal conditions. We characterise our birnessite and reflux products as a time series, including X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM) and extended X-ray absorption fine structure (EXAFS) spectroscopy. In addition we determine Ni speciation and mineral phase associations in a suite of natural marine ferromanganese precipitates, containing intermixed phyllomanganate and todorokite. Our work shows for the first time that Ni significantly slows the transformation of birnessite to todorokite and reduces the

  17. Radioactivity in Norwegian Waters: Distribution in seawater and sediments, and uptake in marine organisms

    Energy Technology Data Exchange (ETDEWEB)

    Heldal, Hilde Elise

    2001-07-01

    Prior to the detonation of the first thermonuclear bomb, small amounts of radioactivity, for example in mineral water, were considered to be health enriching. Negative experiences related to thermonuclear bombs and several nuclear accidents have, however, changed people's attitude towards radioactivity during the past 40-50 years. Today, there is a common concern for regular and potential accidental releases of radioactivity from sources such as Sellafield. Although this is important, incorrect assessments of the effects of these releases (e.g. created by uncritical journalism) have the potential to harm the country's fisheries and economy. Therefore, it is of major importance to document up-to-date levels of radioactive contamination of the marine environment, and be able to place these into the proper perspectives. The main topics of the thesis may be summarised as follows: (1) Distribution of Caesium-137, Plutonium-238, Plutonium-239,240 and Americium-241 in sediments with emphasis on the Spitsbergen-Bear Island area, (2) Uptake of Caesium-137 in phytoplankton representative for the Barents and Norwegian Seas phytoplankton communities (laboratory experiments), (3) Bioaccumulation of Caesium-137 in food webs in the Barents and Norwegian Seas, (4) Geographical variations of Caesium-137 in harbour porpoises (Phocoena phocoena) along the Norwegian coast, (5) Transport times for Technetium-99 from Sellafield to various locations along the Norwegian coast and the Arctic Ocean.

  18. Exopolysaccharide production by a marine Pseudoalteromonas sp. strain isolated from Madeira Archipelago ocean sediments.

    Science.gov (United States)

    Roca, Christophe; Lehmann, Mareen; Torres, Cristiana A V; Baptista, Sílvia; Gaudêncio, Susana P; Freitas, Filomena; Reis, Maria A M

    2016-06-25

    Exopolysaccharides (EPS) are polymers excreted by some microorganisms with interesting properties and used in many industrial applications. A new Pseudoalteromonas sp. strain, MD12-642, was isolated from marine sediments and cultivated in bioreactor in saline culture medium containing glucose as carbon source. Its ability to produce EPS under saline conditions was demonstrated reaching an EPS production of 4.4g/L within 17hours of cultivation, corresponding to a volumetric productivity of 0.25g/Lh, the highest value so far obtained for Pseudoalteromonas sp. strains. The compositional analysis of the EPS revealed the presence of galacturonic acid (41-42mol%), glucuronic acid (25-26mol%), rhamnose (16-22mol%) and glucosamine (12-16mol%) sugar residues. The polymer presents a high molecular weight (above 1000kDa). These results encourage the biotechnological exploitation of strain MD12-642 for the production of valuable EPS with unique composition, using saline by-products/wastes as feedstocks. PMID:26923806

  19. Polyethylene Glycol Drilling Fluid for Drilling in Marine Gas Hydrates-Bearing Sediments: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Lixin Kuang

    2011-01-01

    Full Text Available Shale inhibition, low-temperature performance, the ability to prevent calcium and magnesium-ion pollution, and hydrate inhibition of polyethylene glycol drilling fluid were each tested with conventional drilling-fluid test equipment and an experimental gas-hydrate integrated simulation system developed by our laboratory. The results of these tests show that drilling fluid with a formulation of artificial seawater, 3% bentonite, 0.3% Na2CO3, 10% polyethylene glycol, 20% NaCl, 4% SMP-2, 1% LV-PAC, 0.5% NaOH and 1% PVP K-90 performs well in shale swelling and gas hydrate inhibition. It also shows satisfactory rheological properties and lubrication at temperature ranges from −8 °C to 15 °C. The PVP K-90, a kinetic hydrate inhibitor, can effectively inhibit gas hydrate aggregations at a dose of 1 wt%. This finding demonstrates that a drilling fluid with a high addition of NaCl and a low addition of PVP K-90 is suitable for drilling in natural marine gas-hydrate-bearing sediments.

  20. Quantitative identification and source apportionment of anthropogenic heavy metals in marine sediment of Hong Kong

    Science.gov (United States)

    Zhou, Feng; Guo, Huaicheng; Liu, Lei

    2007-10-01

    Based on ten heavy metals collected twice annually at 59 sites from 1998 to 2004, enrichment factors (EFs), principal component analysis (PCA) and multivariate linear regression of absolute principal component scores (MLR-APCS) were used in identification and source apportionment of the anthropogenic heavy metals in marine sediment. EFs with Fe as a normalizer and local background as reference values was properly tested and suitable in Hong Kong, and Zn, Ni, Pb, Cu, Cd, Hg and Cr mainly originated from anthropogenic sources, while Al, Mn and Fe were derived from rocks weathering. Rotated PCA and GIS mapping further identified two types of anthropogenic sources and their impacted regions: (1) electronic industrial pollution, riparian runoff and vehicle exhaust impacted the entire Victoria Harbour, inner Tolo Harbour, Eastern Buffer, inner Deep Bay and Cheung Chau; and (2) discharges from textile factories and paint, influenced Tsuen Wan Bay and Kwun Tong typhoon shelter and Rambler Channel. In addition, MLR-APCS was successfully introduced to quantitatively determine the source contributions with uncertainties almost less than 8%: the first anthropogenic sources were responsible for 50.0, 45.1, 86.6, 78.9 and 87.5% of the Zn, Pb, Cu, Cd and Hg, respectively, whereas 49.9% of the Ni and 58.4% of the Cr came from the second anthropogenic sources.

  1. Diversity and bioactivity of actinomycetes from marine sediments of the Yellow Sea

    Science.gov (United States)

    Zhang, Shumin; Ye, Liang; Tang, Xuexi

    2012-03-01

    Among the 116 actinomycetes collected from marine sediments of the Yellow Sea, 56 grew slowly and appeared after 2-3 weeks of incubation. Among the 56 strains, only 3 required seawater (SW) for growth, and 21 grew well in the medium prepared with SW rather than distilled water (DW), while the remaining 32 grew well either with SW or with DW. Six representatives with different morphological characteristics, including 1 SW-requiring strain and 5 well-growing with SW strains, were selected for phylogenetic analysis based on 16S rRNA gene. Two strains belong to Micrococcaceae and Nocardiopsaceae respectively. The other 4 strains belong to the family of Streptomycetaceae. In the analyzed 6 strains, one was related to Nocardiopsis spp. and the other three were related to Streptomyces spp., representing new taxa. Bioactivity testing of fermentation products from 3 SW-requiring strains and 21 well-growing with SW strains revealed that 17 strains possessed remarkable activities against gram-positive pathogen or/and tumor cells, suggesting that they were prolific resources for natural drug discovery.

  2. Neutron activation analysis of trace elements in a marine sediment reference material

    International Nuclear Information System (INIS)

    As part of the second intercomparison run of ARCAL-IV, it was analyzed the marine sediment, reference materials PACS-NR CC1 by INAA, in the RP-10 Reactor with a thermal flux of 7,8 x 1013 n/cm2 s. The results obtained (± 1σ,n=4) were: Co: 17,2±0,8 ppm; Cr:97,8±0,6 ppm; Fe: 46,0± 0,7 ppm; Na: 31,0±1,09/kg; Sb: 175±5 ppm; in good agreement with the certified values. The results in ppm (±18,n=4), for non certified elements were:Ba: 730±58; Ce: 25±3; Cs: 3,8±0,8; Eu: 1,00±0,03; Hf: 3,30±0,07; Lu:0,25±0,04; Rb: 44,0±0,9; Sc: 14,40±0,04; Sm: 3,4±0,5; Ta: 0,60±0,03; Tb: 0,5±0,05; Th: 3,80±0,02; U: 2,6±0,4; which are in good agreement with other three Latin American and one European INAA Laboratories. It was used the comparative method with AGV-1, GSP-1 and G-2 , USGS reference materials, as standards. (authors). 7 refs., 4 tabs

  3. Quick, portable toxicity testing of marine or terrigenous fluids, sediments, or chemicals with bioluminescent organism

    International Nuclear Information System (INIS)

    A hand-held, battery-operated instrument, which measures bioluminescence inhibition of the microscopic marine dinoflagellate Pyrocystis lunula, is capable of field-testing substances for toxicity. The organism is sensitive to ppb of strong toxicants. It tolerates some solvents in concentrations necessary for testing lipophylic samples. A test consumes only micrograms of sample. This method requires no adjustments for salinity, pH, color, or turbidity. It has been used successfully to test oil-well drilling fluids, brines produced with oil, waters and sediments from streams and lakes and petroleum-plant effluents containing contaminants such as benzene. The test is non-specific; however, if the substance is known, the end-point effects a direct measurement of its concentration. One-hour toxicity screening tests in the field produce results comparable to the standard four-hour laboratory test. Keeping the sample in the dark during incubation and testing, together with shortness of the overall procedure, eliminates anomalies from light-sensitive substances. Day-to-day variation, as well as among test replicates, is less than 10%. This quick method yields results comparable with a quick test that uses Photobacterium phosphoria, and with 96-hour tests that use Mysidopsis bahia, Artemia salina, Gonyaulax polyedra, Pimephales promelas, Ceriodaphnia dubia, and Cyprinodon variegatus

  4. Radioactivity in Norwegian Waters: Distribution in seawater and sediments, and uptake in marine organisms

    International Nuclear Information System (INIS)

    Prior to the detonation of the first thermonuclear bomb, small amounts of radioactivity, for example in mineral water, were considered to be health enriching. Negative experiences related to thermonuclear bombs and several nuclear accidents have, however, changed people's attitude towards radioactivity during the past 40-50 years. Today, there is a common concern for regular and potential accidental releases of radioactivity from sources such as Sellafield. Although this is important, incorrect assessments of the effects of these releases (e.g. created by uncritical journalism) have the potential to harm the country's fisheries and economy. Therefore, it is of major importance to document up-to-date levels of radioactive contamination of the marine environment, and be able to place these into the proper perspectives. The main topics of the thesis may be summarised as follows: (1) Distribution of Caesium-137, Plutonium-238, Plutonium-239,240 and Americium-241 in sediments with emphasis on the Spitsbergen-Bear Island area, (2) Uptake of Caesium-137 in phytoplankton representative for the Barents and Norwegian Seas phytoplankton communities (laboratory experiments), (3) Bioaccumulation of Caesium-137 in food webs in the Barents and Norwegian Seas, (4) Geographical variations of Caesium-137 in harbour porpoises (Phocoena phocoena) along the Norwegian coast, (5) Transport times for Technetium-99 from Sellafield to various locations along the Norwegian coast and the Arctic Ocean

  5. Report on intercomparison IAEA/SD-N-2 of radionuclide measurements in marine sediment sample

    International Nuclear Information System (INIS)

    The material used in this exercise was a natural medium-grained marine sediment collected in a near-shore area of the North Sea in 1979. Concentrations of radionuclides are often at their detection thresholds in such samples which poses a considerable problem to analysts. In this report results of 238Pu, 239Pu, 240Pu, 241Am, 40K, 137Cs, 226Ra, 228Ra and 228Th measurements submitted by the participants are presented and discussed. They constitute a data base from which reference values have been derived for the purpose of certification. The intercomparison has demonstrated that substantial progress has been made in low-level transuranic measurements in environmental materials. All reported results by gamma-spectroscopy were of high quality providing evidence that activity concentrations of a few millibecquerels per gram can be measured with no special problems if sufficient long counting time can be afforded. Other analytical techniques as alpha-spectrometry proved to yield reliable results when employed by experienced analysts

  6. Neutron activation analysis of stoney spherules from a marine sediment sample

    Science.gov (United States)

    Millar, H. T., Jr.; Englert, P.

    1984-01-01

    The identification of extraterrestrial material in samples collected at the surface of the Earth is discussed. Criteria were established for black magnetic spherules which involve the presence of: Fe, Ni, and Co in iron meteoritic ratios, wustite, and Fe-Ni metal while reliable criteria for stoney spherules are not well established. Neutron activation analysis was performed on eight stony spherules separated from the same marine sediment used by Millard and Finkelman. The 22 elements were determined by Compton suppression and triple coincidence gamma counting. It is found that Fe, Mg, Al, Ni, Cr, Co, Ir, and Sc are the best discriminators between chondritic and terrestrial compositions. Three of the spherules have compositions very close to chondrites and of these, two contain 0.5 and 0.25 ppm Ir. The other five spherules contain much less than chondritic concentrations of Ni but this element may be segregated and lost during ablation of the parent meteorite. One of these five low Ni spherules contains 2.9 ppm Ir while the other four contain less than 0.05 ppm Ir.

  7. Rapid determination of chemical and physical properties in marine sediments using a near-infrared reflectance spectroscopic technique

    International Nuclear Information System (INIS)

    Marine sediments preserve useful information for reconstructing oceanographic conditions and environmental changes in the past. In this study, the authors have evaluated an efficient near-infrared reflectance spectroscopy (NIRS) method for simultaneous determination of total C (TC), total inorganic C (TIC), total organic C (TOC), magnetic susceptibility (MS), the ratio of di- and tri-unsaturated C37 alkenones (U37k'), and δ18O of foraminiferal shells in marine sediments. Near-infrared diffused reflectance spectra (1100-2500 nm) of 172 sediments recovered from the IMAGES Core MD972151, located in the southwestern South China Sea, were analyzed and correlated with the abovementioned parameters using partial least squares regression (PLSR) procedures. The leave-one-out cross-validation results showed that TC and TIC were successfully predicted (r2>0.93) while MS, U37k', and δ18O were estimated with moderate accuracy (r2>0.76). The concentrations of TOC, however, could not be estimated with high precision (r2=0.34), which is possibly a result of the low and narrow range of organic C in this specific core. The results indicate that NIRS has the potential to be a rapid analytical tool for continuous marine core examination, although uncertainties associated with TOC need further investigation

  8. Microbial distributions detected by an oligonucleotide microarray across geochemical zones associated with methane in marine sediments from the Ulleung Basin

    Energy Technology Data Exchange (ETDEWEB)

    Briggs, Brandon R; Graw, Michael; Brodie, Eoin L; Bahk, Jang-Jun; Kim, Sung-Han; Hyun, Jung-Ho; Kim, Ji-Hoon; Torres, Marta; Colwell, Frederick S

    2013-11-01

    The biogeochemical processes that occur in marine sediments on continental margins are complex; however, from one perspective they can be considered with respect to three geochemical zones based on the presence and form of methane: sulfate–methane transition (SMTZ), gas hydrate stability zone (GHSZ), and free gas zone (FGZ). These geochemical zones may harbor distinct microbial communities that are important in biogeochemical carbon cycles. The objective of this study was to describe the microbial communities in sediments from the SMTZ, GHSZ, and FGZ using molecular ecology methods (i.e. PhyloChip microarray analysis and terminal restriction fragment length polymorphism (T-RFLP)) and examining the results in the context of non-biological parameters in the sediments. Non-metric multidimensional scaling and multi-response permutation procedures were used to determine whether microbial community compositions were significantly different in the three geochemical zones and to correlate samples with abiotic characteristics of the sediments. This analysis indicated that microbial communities from all three zones were distinct from one another and that variables such as sulfate concentration, hydrate saturation of the nearest gas hydrate layer, and depth (or unmeasured variables associated with depth e.g. temperature, pressure) were correlated to differences between the three zones. The archaeal anaerobic methanotrophs typically attributed to performing anaerobic oxidation of methane were not detected in the SMTZ; however, the marine benthic group-B, which is often found in SMTZ, was detected. Within the GHSZ, samples that were typically closer to layers that contained higher hydrate saturation had indicator sequences related to Vibrio-type taxa. These results suggest that the biogeographic patterns of microbial communities in marine sediments are distinct based on geochemical zones defined by methane.

  9. Heavy metal concentration in marine sediments and vegetation (caltha palustrvis) from river ramos in bayelsa and delta states of nigeria

    International Nuclear Information System (INIS)

    Heavy metals concentration in marine sediments and vegetation from River Ramos have been studied. Metals such as arsenic, mercury, cadmium, lead, chromium, nickel, iron, copper and zinc were analysed using atomic absorption spectrometer (AAS). The levels of these metals were determined from top and bottom river sediments, side and middle vegetation. The analytical results revealed that arsenic levels were high in all the samples. Secondly, the highest concentration of metals were found on the top sediment (68.00mg/kg dry weight) and vegetation (64.90mg/kg dry weight). Other metals such as mercury, chromium, nickel and iron were found to have high levels. The high levels of the above mentioned heavy metals are the cause of pollution, the concentration due to other metals such as cadmium, lead, copper and zinc was low. The high accumulation of heavy metals in the matrices are due to activities of oil companies and geochemistry of rocks. (author)

  10. Assessment of 238Pu and 239+240Pu, in marine sediments of the oceans Atlantic and Pacific of Guatemala

    International Nuclear Information System (INIS)

    In this investigation samples of marine sediments were taken from 14 places representatives of the oceans coast of Guatemala. For the assesment of 238Pu and 239+240Pu in sediments a radiochemical method was used to mineralize sediments and by ionic interchange it was separated from other elements, after that an electrodeposition of plutonium was made in metallic discs. The radioactivity of plutonium was measured by alpha spectrometry system and the alpha spectrums were obtained. The levels of plutonium are not higher than other countries that shown contamination. The contamination of isotope of 239+240Pu is higher than 238Pu and the contamination by two isotopes of plutonium is higher in the Atlantic than the Pacific ocean

  11. Rare earth elements determination and distribution patterns in sediments of polluted marine environment by instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    Results obtained from the analysis of sediment core samples taken from a fairly polluted marine environment were analyzed for the REE contents to determine the concentrations of La, Ce, Sm, Eu, Tb, Dy and Yb using instrumental neutron activation analysis. Core samples were divided into strata of between 2 to 3 cm intervals and prepared in the powdered form before irradiating them in a TRIGA Mk.II reactor. Down-core concentration profiles of La, Ce, Sm, Eu, Tb, Dy and Yb in 3 core sediments from three sites are obtained. The shale-normalized REE pattern from each site was examined and later used to explain the history of sedimentation by natural processes such as shoreline erosion and weathering products deposited on the seabed and furnishing some baseline data and/or pollution trend occurring within the study area

  12. Biogeographical distribution and diversity of microbes in methane hydrate-bearing deep marine sediments, on the Pacific Ocean Margin

    DEFF Research Database (Denmark)

    Inagaki, F.; Nunoura, T.; Nakagawa, S.; Teske, A.; Lever, M.; Lauer, A.; Suzuki, M.; Takai, K.; Delwiche, M.; Colwell, FS; Nealson, KH; Horikoshi, K.; D'Hondt, S.; Jørgensen, BB

    2006-01-01

    The deep subseafloor biosphere is among the least-understood habitats on Earth, even though the huge microbial biomass therein plays an important role for potential long-term controls on global biogeochemical cycles. We report here the vertical and geographical distribution of microbes and their...... phylogenetic diversities in deeply buried marine sediments of the Pacific Ocean Margins. During the Ocean Drilling Program Legs 201 and 204, we obtained sediment cores from the Peru and Cascadia Margins that varied with respect to the presence of dissolved methane and methane hydrate. To examine differences in...... prokaryotic distribution patterns in sediments with or without methane hydrates, we studied > 2,800 clones possessing partial sequences (400-500 bp) of the 16S rRNA gene and 348 representative clone sequences (approximate to 1 kbp) from the two geographically separated subseafloor environments. Archaea of the...

  13. Basin-scale controls on the molybdenum-isotope composition of seawater during Oceanic Anoxic Event 2 (Late Cretaceous)

    Science.gov (United States)

    Dickson, Alexander J.; Jenkyns, Hugh C.; Porcelli, Donald; van den Boorn, Sander; Idiz, Erdem

    2016-04-01

    It is well established that the burial of organic carbon in marine sediments increased dramatically at a global scale at the Cenomanian-Turonian boundary (Oceanic Anoxic Event 2: OAE-2, ∼94 Myr ago, Late Cretaceous). Many localities containing chemostratigraphic expressions of this event are not, however, enriched in organic carbon, and point to a heterogeneous set of oceanographic and environmental processes operating in different ocean basins. These processes are difficult to reconstruct because of the uneven geographical distribution of sites recording OAE-2, thus limiting our understanding of the causes and palaeoceanographic consequences of the environmental changes that occurred at this time. A new, highly resolved molybdenum-isotope dataset is presented from the Cape Verde Basin (southern proto-North Atlantic Ocean) and a lower resolution record from the Tarfaya Basin, Morocco. The new data reveal periodic oscillations in the Mo-isotope composition of proto-North Atlantic Ocean sediments, from which coupled changes in the dissolved sulphide concentration and Mo inventories of the basin seawater can be inferred. The cyclic variations in sedimentary Mo-isotope compositions can be hypothetically linked to regional changes in the depth of the chemocline, and in the rate of seawater exchange between basinal waters and global seawater. The new data suggest that a global seawater Mo-isotope composition of ∼1.2‰ was reached very soon after the onset of OAE-2, implying a rapid expansion of marine deoxygenation coeval with, or slightly preceding, enhanced global rates of organic-carbon burial. During OAE-2, the modelled flux of Mo into anoxic sediments is likely to have been ∼60-125 times greater than at the present day, although the spatial extent of anoxia is unlikely to have been greater than 10% of the total seafloor.

  14. Distribution of clay minerals in marine sediments off Chennai, Bay of Bengal, India: Indicators of sediment sources and transport processes .

    Digital Repository Service at National Institute of Oceanography (India)

    Veerasingam, S.; Venkatachalapathy, R.; Ramkumar, T.

    diffraction analysis was performed on powdered sediment samples using a Seifert (JSO-DEBYEFLEX 2002) X-ray diffractometer having a curved graphite crystal diffracted monochromator, with a source of CuK� radiation and a NaI (TI) scintillation counter detector... scale, but are not yet used routinely for sediment analysis (Linge, 2008). Mineralogical investigations were generally performed by using X-ray 1 Dr., CSIR–National Institute of Oceanography...

  15. Potential influence of CO2 release from a carbon capture storage site on release of trace metals from marine sediment

    International Nuclear Information System (INIS)

    One of the main risks of CCS (Carbon Capture and Storage) is CO2 leakage from a storage site. The influence of CO2 leakage on trace metals leaching from contaminated marine sediment in a potential storage area (Northern Spain) is addressed using standardized leaching tests. The influence of the pH of the leaching solution on the leachates is evaluated using deionized water, natural seawater and acidified seawater at pH = 5, 6 and 7, obtained by CO2 bubbling. Equilibrium leaching tests () were performed at different liquid–solid ratios and the results of ANC/BNC leaching test () were modeled using Visual Minteq. Equilibrium tests gave values of the final pH for all seawater leachates between 7 and 8 due to the high acid neutralization capacity of the sediment. Combining leaching test results and geochemical modeling provided insight in the mechanisms and prediction of trace metals leaching in acidified seawater environment. - Highlights: ► Tier structured approach for assessment of the release of metals from sediment. ► Leaching test as useful tool to evaluate risks of a CCS site due to CO2 leakages. ► Prediction of metal release from marine sediment in contact to acidified seawater. ► Metal and DOC release in equilibrium leaching tests as function of L/S ratio and pH. ► Geochemical modeling of chemical species release from contaminated sediment. - Metal mobility from contaminated sediment under CO2 leakages in CCS sites using leaching tests.

  16. Effects of the antibiotic ciprofloxacin on the bacterial community structure and degradation of pyrene in marine sediment

    Energy Technology Data Exchange (ETDEWEB)

    Naeslund, Johan [Department of Systems Ecology, Stockholm University, 106 91 Stockholm (Sweden)], E-mail: johan@ecology.su.se; Hedman, Jenny E.; Agestrand, Cecilia [Department of Systems Ecology, Stockholm University, 106 91 Stockholm (Sweden)

    2008-11-21

    The ecological consequences of antibiotics in the aquatic environment have been an issue of concern over the past years due to the potential risk for negative effects on indigenous microorganisms. Microorganisms provide important ecosystem services, such as nutrient recycling, organic matter mineralization and degradation of pollutants. In this study, effects of exposure to the antibiotic ciprofloxacin on the bacterial diversity and pollutant degradation in natural marine sediments were studied using molecular methods (T-RFLP) in combination with radiorespirometry. In a microcosm experiment, sediment spiked with {sup 14}C-labelled pyrene was exposed to five concentrations of ciprofloxacin (0, 20, 200, 1000 and 2000 {mu}g L{sup -1}) in a single dose to the overlying water. The production of {sup 14}CO{sub 2} (i.e. complete mineralization of pyrene) was measured during 11 weeks. Sediment samples for bacterial community structure analysis were taken after 7 weeks. Results showed a significant dose-dependent inhibition of pyrene mineralization measured as the total {sup 14}CO{sub 2} production. The nominal EC{sub 50} was calculated to 560 {mu}g L{sup -1}, corresponding to 0.4 {mu}g/kg d.w. sediment. The lowest effect concentration on the bacterial community structure was 200 {mu}g L{sup -1}, which corresponds to 0.1 {mu}g/kg d.w. sediment. Our results show that antibiotic pollution can be a potential threat to both bacterial diversity and an essential ecosystem service they perform in marine sediment.

  17. The Microworld of Marine-Bacteria

    DEFF Research Database (Denmark)

    JØRGENSEN, BB

    1995-01-01

    Microsensor studies show that the marine environment in the size scale of bacteria is physically and chemically very different from the macroenvironment. The microbial world of the sediment-water interface is thus dominated by water viscosity and steep diffusion gradients. Because of the diverse...... metabolism types, bacteria in the mostly anoxic sea floor play an important role in the major element cycles of the ocean. The communities of giant, filamentous sulfur bacteria that live in the deep-sea hydrothermal vents or along the Pacific coast of South America are presented here as examples....

  18. Transfer of radionuclides from high polluted bottom sediments to marine organisms through benthic food chain in post Fukushima period

    Science.gov (United States)

    Bezhenar, Roman; Jung, Kyung Tae; Maderich, Vladimir; Willemsen, Stefan; de With, Govert; Qiao, Fangli

    2015-04-01

    A catastrophic earthquake and tsunami occurred on March 11, 2011 and severely damaged the Fukushima Daiichi Nuclear Power Plant (FDNPP) that resulted in an uncontrolled release of radioactivity into air and ocean. Around 80% of the radioactivity released due to the FDNPP accident in March-April 2011 was either directly discharged into the ocean or deposited onto the ocean surface from the atmosphere. A large amount of long-lived radionuclides (mainly Cs-137) were released into the environment. The concentration of radionuclides in the ocean reached a maximum in mid-April of 2011, and then gradually decreased. From 2011 the concentration of Cs-137 in water essentially fell except the area around the FDNPP where leaks of contaminated water are continued. However, in the bottom sediment high concentrations of Cs-137 were found in the first months after the accident and slowly decreased with time. Therefore, it should be expected that a time delay is found of sediment-bound radionuclides in marine organisms. For the modeling of radionuclide transfer from highly polluted bottom sediments to marine organisms the dynamical food chain model BURN-POSEIDON (Heling et al, 2002; Maderich et al., 2014) was extended. In this model marine organisms are grouped into a limited number of classes based on their trophic level and type of species. These include: phytoplankton, zooplankton, fishes (two types: piscivorous and non-piscivorous), crustaceans, and molluscs for pelagic food chain and bottom sediment invertebrates, demersal fishes and bottom predators for benthic food chain and whole water column predators feeding by pelagial and benthic fishes. Bottom invertebrates consume organic parts of bottom sediments with adsorbed radionuclides which then migrate through the food chain. All organisms take radionuclides directly from water as well as via food. In fishes where radioactivity is not homogeneously distributed over all tissues of the organism, it is assumed that radionuclide

  19. Paleomagnetic and paleoenvironmental implications of magnetofossil occurrences in late Miocene marine sediments from the Guadalquivir Basin, SW Spain.

    Science.gov (United States)

    Larrasoaña, Juan C; Liu, Qingsong; Hu, Pengxiang; Roberts, Andrew P; Mata, Pilar; Civis, Jorge; Sierro, Francisco J; Pérez-Asensio, José N

    2014-01-01

    Although recent studies have revealed more widespread occurrences of magnetofossils in pre-Quaternary sediments than have been previously reported, their significance for paleomagnetic and paleoenvironmental studies is not fully understood. We present a paleo- and rock-magnetic study of late Miocene marine sediments recovered from the Guadalquivir Basin (SW Spain). Well-defined paleomagnetic directions provide a robust magnetostratigraphic chronology for the two studied sediment cores. Rock magnetic results indicate the dominance of intact magnetosome chains throughout the studied sediments. These results provide a link between the highest-quality paleomagnetic directions and higher magnetofossil abundances. We interpret that bacterial magnetite formed in the surface sediment mixed layer and that these magnetic particles gave rise to a paleomagnetic signal in the same way as detrital grains. They, therefore, carry a magnetization that is essentially identical to a post-depositional remanent magnetization, which we term a bio-depositional remanent magnetization. Some studied polarity reversals record paleomagnetic directions with an apparent 60-70 kyr recording delay. Magnetofossils in these cases are interpreted to carry a biogeochemical remanent magnetization that is locked in at greater depth in the sediment column. A sharp decrease in magnetofossil abundance toward the middle of the studied boreholes coincides broadly with a major rise in sediment accumulation rates near the onset of the Messinian salinity crisis (MSC), an event caused by interruption of the connection between the Mediterranean Sea and the Atlantic Ocean. This correlation appears to have resulted from dilution of magnetofossils by enhanced terrigenous inputs that were driven, in turn, by sedimentary changes triggered in the basin at the onset of the MSC. Our results highlight the importance of magnetofossils as carriers of high-quality paleomagnetic and paleoenvironmental signals even in

  20. Diversity and abundance of sulfate-reducing microorganisms in the sulfate and methane zones of a marine sediment, Black Sea RID A-8182-2008

    DEFF Research Database (Denmark)

    Leloup, Julie; Loy, Alexander; Knab, Nina J.;

    2007-01-01

    The Black Sea, with its highly sulfidic water column, is the largest anoxic basin in the world. Within its sediments, the mineralization of organic matter occurs essentially through sulfate reduction and methanogenesis. In this study, the sulfate-reducing community was investigated in order to...... branching sequences which might represent Gram-positive spore-forming sulfate- and/or sulfite-reducing microorganisms. We thus hypothesize that terminal carbon mineralization in surface sediments of the Black Sea is largely due to the sulfate reduction activity of previously hidden SRM. Although these novel...... SRM were also abundant in sulfate-poor, methanogenic areas of the Black Sea sediment, their activities and possibly very versatile metabolic capabilities remain subject of further study....

  1. Anaerobic animals from an ancient, anoxic ecological niche

    OpenAIRE

    Martin William; Mentel Marek

    2010-01-01

    Abstract Tiny marine animals that complete their life cycle in the total absence of light and oxygen are reported by Roberto Danovaro and colleagues in this issue of BMC Biology. These fascinating animals are new members of the phylum Loricifera and possess mitochondria that in electron micrographs look very much like hydrogenosomes, the H2-producing mitochondria found among several unicellular eukaryotic lineages. The discovery of metazoan life in a permanently anoxic and sulphidic environme...

  2. Integrating mercury injection and nitrogen adsorption data to characterize marine sediment pore systems: An example from the Nankai Trough

    Science.gov (United States)

    Daigle, H.; Thomas, B.

    2013-12-01

    Fine-grained, clay-rich marine sediments typically exhibit complex pore geometries due to the presence of high-aspect-ratio clay particles, nannofossils, and diagenetically altered grain fragments. The pore systems in these sediments have a wide range of shapes and may contain significant pore volume in mesopores (1-25 nm radius) and micropores (pore size measurements difficult, even in samples with high porosity. Porosity values from mercury injection capillary pressure (MICP) measurements performed on samples from Integrated Ocean Drilling Program (IODP) Sites C0011, C0012, and C0018 in the Nankai Trough offshore Japan were compared to porosity determined by proton nuclear magnetic resonance (NMR) in the laboratory. The MICP porosities were systematically lower than the NMR porosities by up to 26% of the NMR porosity value. This porosity mismatch is due to the presence of pores with radii smaller than the effective lower limit of MICP measurements, which is 10-40 nm for this data set. Nitrogen gas adsorption offers a means to characterize pores between ~0.87 nm and ~100 nm radius, thus measuring the portion of the pore size distribution not investigated by MICP measurements. Combining MICP and nitrogen gas adsorption data yields a more complete characterization of the pore system of marine sediments. Merged MICP and nitrogen gas adsorption data obtained for the Nankai Trough samples yield porosity values that more accurately match the NMR porosity values, indicating that the entire pore space of the samples can be measured by a combination of the two techniques. These samples possess significant quantities of porosity below the resolution of MICP (>10% of pore volume), even in samples with porosity exceeding 65%. This work illustrates the complexity of marine sediment pore systems even at shallow depths of burial, and provides a new method for assessing pore sizes in scientific ocean drilling studies.

  3. [Residues and risk assessment of polycyclic aromatic hydrocarbons in the surface sediments and marine organisms from Dapeng Bay, Shenzhen].

    Science.gov (United States)

    Sun, Run-Xia; Ke, Chang-Liang; Gu, Yang-Guang; Lu, Teng-Teng; Du, Fei-Yan; Ma, Sheng-Wei; Lin, Qin

    2013-10-01

    In order to assess contamination by polycyclic aromatic hydrocarbons (PAHs), surface sediments and marine organism samples of fish, shrimp and shellfish were collected from the Dapeng Bay, Shenzhen in October 2011. Concentrations fof sixteen priority PAHs were determined by gas chromatography and mass spectrometry (GC-MS). The total concentrations of PAHs (Sigma PAHs ) ranged from 216. 56 ng.g-1 to 1 314. 92 ng.g-1 dry weight in sediment samples and from 70. 88 ng.g-1 to 251.90 ng.g-1 wet weight in biological samples, respectively. The mean concentration was the highest in fish (171.52 ng.g-1 ), followed by mussel (134.75 ng.g-1) and shrimp (123.35 ng.g-1) in the studied marine organisms. Compared with those in other water bodies around the world, PAHs pollution in the studied area was at medium level. The dominant fraction in the surface sediments was the 4-ring PAHs. Identification of PAH sources suggested that PAHs in Dapeng Bay were likely originated from both pyrolytic and petrogenic sources. The most abundant PAHs were 3-ring PAHs in the tissues of organisms, which may be governed by their feeding behaviors, habitats, and bioavailability of PAHs. Ecological risk assessment indicated that PAHs in surface sediments might have adverse impacts on local ecosystem. Health risk analysis revealed that the potency equivalent concentrations of BaP to the total PAHs in marine organisms from Dapeng Bay were relatively high and may cause some concerns on human health by consumption. PMID:24364300

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

    OpenAIRE

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

    1996-01-01

    Naphthalene- and phenanthrene-degrading bacteria in Puget Sound sediments were enumerated by most-probable-number enumeration procedures. Sediments from a creosote-contaminated Environmental Protection Agency Superfund Site (Eagle Harbor) contained from 10(4) to 10(7) polycyclic aromatic hydrocarbon (PAH)-degrading bacteria g (dry weight) of sediment-1, whereas the concentration at an uncontaminated site ranged from 10(3) to 10(4) g of sediment(-1). Isolates of PAH-degrading bacteria were obt...

  5. Bioturbating shrimp alter the structure and diversity of bacterial communities in coastal marine sediments.

    Science.gov (United States)

    Laverock, Bonnie; Smith, Cindy J; Tait, Karen; Osborn, A Mark; Widdicombe, Steve; Gilbert, Jack A

    2010-12-01

    Bioturbation is a key process in coastal sediments, influencing microbially driven cycling of nutrients as well as the physical characteristics of the sediment. However, little is known about the distribution, diversity and function of the microbial communities that inhabit the burrows of infaunal macroorganisms. In this study, terminal-restriction fragment length polymorphism analysis was used to investigate variation in the structure of bacterial communities in sediment bioturbated by the burrowing shrimp Upogebia deltaura or Callianassa subterranea. Analyses of 229 sediment samples revealed significant differences between bacterial communities inhabiting shrimp burrows and those inhabiting ambient surface and subsurface sediments. Bacterial communities in burrows from both shrimp species were more similar to those in surface-ambient than subsurface-ambient sediment (R=0.258, P<0.001). The presence of shrimp was also associated with changes in bacterial community structure in surrounding surface sediment, when compared with sediments uninhabited by shrimp. Bacterial community structure varied with burrow depth, and also between individual burrows, suggesting that the shrimp's burrow construction, irrigation and maintenance behaviour affect the distribution of bacteria within shrimp burrows. Subsequent sequence analysis of bacterial 16S rRNA genes from surface sediments revealed differences in the relative abundance of bacterial taxa between shrimp-inhabited and uninhabited sediments; shrimp-inhabited sediment contained a higher proportion of proteobacterial sequences, including in particular a twofold increase in Gammaproteobacteria. Chao1 and ACE diversity estimates showed that taxon richness within surface bacterial communities in shrimp-inhabited sediment was at least threefold higher than that in uninhabited sediment. This study shows that bioturbation can result in significant structural and compositional changes in sediment bacterial communities, increasing

  6. Paleomagnetic and paleoenvironmental implications of magnetofossil occurrences in late Miocene marine sediments from the Guadalquivir Basin, SW Spain

    Directory of Open Access Journals (Sweden)

    Juan Cruz Larrasoaña

    2014-03-01

    Full Text Available Although recent studies have revealed more widespread occurrences of magnetofossils in pre-Quaternary sediments than has been previously reported, their significance for paleomagetic and paleoenvironmental studies is not fully understood. We present a paleo- and rock-magnetic study of late Miocene marine sediments recovered from the Guadalquivir Basin (SW Spain. Well-defined paleomagnetic directions provide a robust magnetostratigraphic chronology for the two studied sediment cores. Rock magnetic results indicate the dominance of intact magnetosome chains throughout the studied sediments. These results provide a link between the highest-quality paleomagnetic directions and higher magnetofossil abundances. We interpret that bacterial magnetite formed in the surface sediment mixed layer and that these magnetic particles gave rise to a paleomagnetic signal in the same way as detrital grains. They, therefore, carry a magnetization that is essentially identical to a post-depositional remanent magnetization and that we term a bio-depositional remanent magnetization (BDRM. Some studied polarity reversals record paleomagnetic directions that appear to be delayed by 60-70 kyr. Magnetofossils in these cases are interpreted to carry a biogeochemical remanent magnetization (BGRM that is locked in at greater depth in the sediment column. A sharp decrease in magnetofossil abundance toward the middle of the studied boreholes broadly coincides with a major rise in sediment accumulation rates near the onset of the Messinian salinity crisis (MSC, an event caused by interruption of the connection between the Mediterranean Sea and the Atlantic Ocean. This correlation appears to have resulted from dilution of magnetofossils by enhanced terrigenous inputs that were driven, in turn, by sedimentary changes triggered in the basin at the onset of the MSC. Our study highlights the importance of magnetofossils as carriers of high-quality paleomagnetic and

  7. Distribution of naturally occurring radioactivity and 137Cs in the marine sediment of Farasan island, southern red sea, Saudi Arabia

    International Nuclear Information System (INIS)

    The present work is a part of a project dedicated to measure the marine radioactivity near the Saudi Arabian coast of the Red Sea and Arabian Gulf for establishing a marine radioactivity database, which includes necessary information on the background levels of both naturally occurring and man-made radionuclides in the marine environment. Farasan Islands is a group of 84 islands (archipelago), under the administration of the Kingdom of Saudi Arabia, in the Red Sea with its main island of Farasan, which is 50 km off the coast of Jazan City. The levels of natural radioactivity of 238U, 235U, 226Ra, 232Thand 40K and man-made radionuclides such as 137Cs in the grab sediment and water samples around Farasan Island have been measured using gamma-ray spectroscopy. The average activity concentrations of 238U, 235U, 226Ra, 232Th, 40K and 137Cs in the sediment samples were found to be 35.46, 1.75, 3.31, 0.92, 34.34 and 0.14 Bq kg-1, respectively. (authors)

  8. Rare earth elements determination and distribution patterns in surface marine sediments of the South China Sea by INAA, Malaysia

    International Nuclear Information System (INIS)

    Results obtained from the analysis of sediments surface samples taken from rivers mouth and polluted marine environment were analyzed for REE contents to determine the concentrations of La, Ce, Sm, Eu, Tb, Dy, Lu and Yb using instrumental neutron activation analysis. Thirty surface samples were collected from ten sites in the coastal marine sediments of the South China Sea along 957 km stretch of the east coast of Peninsular Malaysia. The samples prepared in the powdered form before irradiating them in a neutron flux of ∼4 x 1012 n cm-2 s-1 at 750 kW power using the TRIGA Mark II research reactor at Malaysian Institute for Nuclear Technology (MINT). Results of the total concentration are used to establish baseline data in environmental pollution assessment and to develop the correlations between the Ce/Ce* anomalies and the distribution patterns of some the light rare earth elements (LREEs) and the heavy rare earth elements (HREEs). The Chondrite-normalized REE pattern from each site examined and used to explain the sedimentation patterns by anthropogenic activities and by natural processes such as shoreline erosion, weathering deposits. Shale-normalized (NASC) patterns suggest enrichment of LREEs relative to the HREEs with a positive Ce/Ce* anomaly. Validation of the used method was done using a Soil-7 SRM. (author)

  9. Environmental effects of dredging. A chronic sublethal sediment bioassay with the marine polychaete nereis (Neanthes) arenaceodentata

    Energy Technology Data Exchange (ETDEWEB)

    Dillon, T.M.; Moore, D.W.; Bridges, T.S.

    1995-01-01

    This note provides a general overview of a new 28-day chronic sublethal sediment bioassay designed for the regulatory evaluation of dredged material. The bioassay uses survival and growth rate endpoints with the polychaete Nereis (Neanthes) arenaceodentata. The primary technical reference for this new bioassay is Dillon, Moore, and Reish (in press), upon which this overview is based. Sediment bioassays are used to assess the aggregate toxicity of sediment associated anthropogenic chemicals. Historically, these bioassays have measured survival of highly sensitive species following acute exposures (10 days). A new generation of sediment bioassays is being developed in which the subtle, sublethal response of test species is measured following chronic sediment exposures (Dillon 1993).

  10. Geochemical, metagenomic and metaproteomic insights into trace metal utilization by methane-oxidizing microbial consortia in sulphidic marine sediments

    Energy Technology Data Exchange (ETDEWEB)

    Glass, DR. Jennifer [California Institute of Technology, Pasadena; Yu, DR. Hang [California Institute of Technology, Pasadena; Steele, Joshua [California Institute of Technology, Pasadena; Dawson, Katherine [California Institute of Technology, Pasadena; Sun, S [University of California, San Diego; Chourey, Karuna [ORNL; Pan, Chongle [ORNL; Hettich, Robert {Bob} L [ORNL; Orphan, V [California Institute of Technology, Pasadena

    2013-01-01

    Microbes have obligate requirements for trace metals in metalloenzymes that catalyse important biogeochemical reactions. In anoxic methane- and sulphiderich environments, microbes may have unique adaptations for metal acquisition and utilization because of decreased bioavailability as a result of metal sulphide precipitation. However, micronutrient cycling is largely unexplored in cold ( 10 C) and sulphidic (> 1 mM H2S) deep-sea methane seep ecosystems. We investigated trace metal geochemistry and microbial metal utilization in methane seeps offshore Oregon and California, USA, and report dissolved concentrations of nickel (0.5 270 nM), cobalt (0.5 6 nM), molybdenum (10 5600 nM) and tungsten (0.3 8 nM) in Hydrate Ridge sediment porewaters. Despite low levels of cobalt and tungsten, metagenomic and metaproteomic data suggest that microbial consortia catalysing anaerobic oxidation of methane (AOM) utilize both scarce micronutrients in addition to nickel and molybdenum. Genetic machinery for cobalt-containing vitamin B12 biosynthesis was present in both anaerobic methanotrophic archaea (ANME) and sulphate-reducing bacteria. Proteins affiliated with the tungsten-containing form of formylmethanofuran dehydrogenase were expressed in ANME from two seep ecosystems, the first evidence for expression of a tungstoenzyme in psychrophilic microorganisms. Overall, our data suggest that AOM consortia use specialized biochemical strategies to overcome the challenges of metal availability in sulphidic environments.

  11. Geochemical, metagenomic and metaproteomic insights into trace metal utilization by methane-oxidizing microbial consortia in sulfidic marine sediments

    Energy Technology Data Exchange (ETDEWEB)

    Glass, DR. Jennifer [California Institute of Technology, Pasadena; Yu, DR. Hang [California Institute of Technology, Pasadena; Steele, Joshua [California Institute of Technology, Pasadena; Dawson, Katherine [California Institute of Technology, Pasadena; Sun, S [University of California, San Diego; Chourey, Karuna [ORNL; Hettich, Robert {Bob} L [ORNL; Orphan, V [California Institute of Technology, Pasadena

    2014-01-01

    Microbes have obligate requirements for trace metals in metalloenzymes that catalyze important biogeochemical reactions. In anoxic methane- and sulfide-rich environments, microbes may have unique adaptations for metal acquisition and utilization due to decreased bioavailability as a result of metal sulfide precipitation. However, micronutrient cycling is largely unexplored in cold ( 10 C) and sulfidic (>1 mM H2S) deep-sea methane seep ecosystems. We investigated trace metal geochemistry and microbial metal utilization in methane seeps offshore Oregon and California, USA, and report dissolved concentrations of nickel (0.5-270 nM), cobalt (0.5-6 nM), molybdenum (10-5,600 nM) and tungsten (0.3-8 nM) in Hydrate Rid