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Sample records for sandy marine sediments

  1. 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.

  2. 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

    2000-01-01

    layers of the sediment. Algal photosynthetic activity and nitrogen uptake reduced nitrogen effluxes and denitrification rates. Sulfate reduction was the most important pathway for carbon mineralization in the sediments of the shallow-water station. In contrast, high bottom-water NO3- concentrations...... 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......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...

  3. Effects of deposition of heavy-metal-polluted harbor mud on microbial diversity and metal resistance in sandy marine sediments

    DEFF Research Database (Denmark)

    Toes, Ann-Charlotte M; Finke, Niko; Kuenen, J Gijs

    2008-01-01

    Deposition of dredged harbor sediments in relatively undisturbed ecosystems is often considered a viable option for confinement of pollutants and possible natural attenuation. This study investigated the effects of deposition of heavy-metal-polluted sludge on the microbial diversity of sandy...

  4. The Influence of Water Column Hypoxia on the Behaviour of Manganese and Iron in Sandy Coastal Marine Sediment

    Science.gov (United States)

    Kristiansen, K. D.; Kristensen, E.; Jensen, E. M. H.

    2002-10-01

    The influence of bottom water hypoxia on manganese, iron and sulfur biogeochemistry was examined in sandy sediment from the shallow coastal lagoon, Fællesstrand, Denmark. The organic-poor sediment at Fællesstrand experiences occasional coverage of floating macroalgae and variable degrees of hypoxia at the sediment-water interface, resulting in dramatic changes in metal behaviour. The narrow peaks and steep gradients in Mn and Fe oxides as well as porewater Mn 2+ and Fe 2+ observed in the upper 2-3 cm of the sediment under fully oxic conditions indicate intense metal reduction-oxidation cycles. The Fe zones were generally displaced about 1 cm downwards compared with the Mn zones due to differences in reactivity. At lowered O 2 conditions in the overlying water, Mn oxides gradually disappeared followed by Fe oxides. The subsequent diffusive loss of Mn 2+ and Fe 2+ to the overlying water was inversely related to the O 2 concentration in the overlying water. The ability of the sediment to retain upward diffusion of H 2S (sulfide retaining capacity) gradually disappeared at lowered O 2 concentrations in a temporal pattern closely related to the changes in reactive Mn and Fe present. The sulfide retaining capacity is sustained for about 14 days under anoxia in Fællesstrand sediment. After 28 days of anoxia, 30-35% of the total Mn and Fe pools initially present in the sediment was lost. Despite the relatively low metal content, this organic-poor sediment may withstand hypoxic conditions in the bottom water (e.g. caused by coverage with floating macroalgae) and is thus capable of maintaining an intact benthic community for extended periods of time.

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

    Science.gov (United States)

    Valdemarsen, Thomas; Kristensen, Erik

    2010-03-01

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

  6. Stable isotope biogeochemistry of the sulfur cycle in modern marine sediments: I. Seasonal dynamics in a temperate intertidal sandy surface sediment.

    Science.gov (United States)

    Böttcher, Michael; Hespenheide, Britta; Brumsack, Hans-Jürgen; Bosselmann, Katja

    2004-12-01

    A biogeochemical and stable isotope geochemical study was carried out in surface sediments of an organic-matter poor temperate intertidal sandy surface sediment (German Wadden Sea of the North Sea) to investigate the activity of sulfate-reducing bacteria and the dynamics of the vertical partitioning of sedimentary sulfur, iron, and manganese species in relation to the availability of total organic carbon (TOC) and mud contents. The contents and stable isotopic compositions ((34)S/(32)S) of total reduced inorganic sulfur species (TRIS) and dissolved sulfate were measured. Maximum oxygen penetration depths were estimated from the onset of a blackening of the sediments due to FeS accumulation and ranged from 5 to 10 mm below surface (mmbsf). A zone of relatively moderate relative organic-matter enrichment was found between 5 and 20 mmbsf leading to enhanced activities of sulfate-reducing bacteria with sulfate-reduction rates (SRR) up to 350 nmol cm(-3) d(-1). Below this zone, microbial SRR dropped significantly. Depth integrated SRR seem to depend not only on temperature but also on the availability of reactive organic matter. The sulfur-isotopic composition of TRIS was depleted in (34)S by 33-40 per thousand with respect to coexisting dissolved sulfate (constant at about +21 per thousand vs. Vienna-Canyon Diablo Troilite (V-CDT)). Since sulfate reduction is not limited by dissolved sulfate (open system), depth variations of the isotopic composition of TRIS reflect changes in overall isotope effect due to superimposed microbial and abiotic reactions. Most of the solid-phase iron and manganese was bonded to (non-reactive) heavy minerals. However, a layer of reactive Fe(III) and Mn(IV) oxi(hydroxi)des was found in the uppermost sediment section due to re-oxidation of dissolved Fe(II) and Mn(II) species at the sediment-water interface. Metal cycling below the surface is at least partially coupled to intense sulfur cycling.

  7. Light Penetration and Light-Intensity in Sandy Marine-Sediments Measured with Irradiance and Scalar Irradiance Fiberoptic Microprobes Rid A-1977-2009

    DEFF Research Database (Denmark)

    KUHL, M.; LASSEN, C.; JØRGENSEN, BB

    1994-01-01

    of downwelling irradiance underestimated the total quantum flux available, i.e. scalar irradiance, by > 100 % throughout the sediment. Attenuation coefficents of scalar irradiance, downwelling irradiance and upwelling irradiance were, however, similar in deeper sediment layers where the light field became more...... surface ranging from 180 % of incident collimated light in the coarsest sediment (250 to 500 mum grain size) up to 280 % in the finest sediment ( 1 mm in the coarsest sediments. Below 1 mm, light was attenuated exponentially with depth in all sediments. Light attenuation coefficients decreased...... with increasing particle size, and infrared light penetrated deeper than visible light in all sediments. Attenuation spectra of scalar irradiance exhibited the strongest attenuation at 450 to 500 ran, and a continuous decrease in attenuation coefficent towards the longer wavelengths was observed. Measurements...

  8. Sulfur diagenesis in marine sediments

    Science.gov (United States)

    Goldhaber, M.

    1985-01-01

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

  9. Glider observations and modeling of sediment transport in Hurricane Sandy

    Science.gov (United States)

    Miles, Travis; Seroka, Greg; Kohut, Josh; Schofield, Oscar; Glenn, Scott

    2015-03-01

    Regional sediment resuspension and transport are examined as Hurricane Sandy made landfall on the Mid-Atlantic Bight (MAB) in October 2012. A Teledyne-Webb Slocum glider, equipped with a Nortek Aquadopp current profiler, was deployed on the continental shelf ahead of the storm, and is used to validate sediment transport routines coupled to the Regional Ocean Modeling System (ROMS). The glider was deployed on 25 October, 5 days before Sandy made landfall in southern New Jersey (NJ) and flew along the 40 m isobath south of the Hudson Shelf Valley. We used optical and acoustic backscatter to compare with two modeled size classes along the glider track, 0.1 and 0.4 mm sand, respectively. Observations and modeling revealed full water column resuspension for both size classes for over 24 h during peak waves and currents, with transport oriented along-shelf toward the southwest. Regional model predictions showed over 3 cm of sediment eroded on the northern portion of the NJ shelf where waves and currents were the highest. As the storm passed and winds reversed from onshore to offshore on the southern portion of the domain waves and subsequently orbital velocities necessary for resuspension were reduced leading to over 3 cm of deposition across the entire shelf, just north of Delaware Bay. This study highlights the utility of gliders as a new asset in support of the development and verification of regional sediment resuspension and transport models, particularly during large tropical and extratropical cyclones when in situ data sets are not readily available.

  10. Impact of redox-stratification on the diversity and distribution of bacterial communities in sandy reef sediments in a microcosm

    Science.gov (United States)

    Gao, Zheng; Wang, Xin; Hannides, Angelos K.; Sansone, Francis J.; Wang, Guangyi

    2011-11-01

    Relationships between microbial communities and geochemical environments are important in marine microbial ecology and biogeochemistry. Although biogeochemical redox stratification has been well documented in marine sediments, its impact on microbial communities remains largely unknown. In this study, we applied denaturing gradient gel electrophoresis (DGGE) and clone library construction to investigate the diversity and stratification of bacterial communities in redox-stratified sandy reef sediments in a microcosm. A total of 88 Operational Taxonomic Units (OTU) were identified from 16S rRNA clone libraries constructed from sandy reef sediments in a laboratory microcosm. They were members of nine phyla and three candidate divisions, including Proteobacteria ( Alpha-, Beta-, Gamma-, Delta-, and Epsilonproteobacteria), Actinobacteria, Acidobacteria, Bacteroidetes, Chloroflexi, Cyanobacteria, Firmicutes, Verrucomicrobia, Spirochaetes, and the candidate divisions WS3, SO31 and AO19. The vast majority of these phylotypes are related to clone sequences from other marine sediments, but OTUs of Epsilonproteobacteria and WS3 are reported for the first time from permeable marine sediments. Several other OTUs are potential new bacterial phylotypes because of their low similarity with reference sequences. Results from the 16S rRNA, gene clone sequence analyses suggested that bacterial communities exhibit clear stratification across large redox gradients in these sediments, with the highest diversity found in the anoxic layer (15-25 mm) and the least diversity in the suboxic layer (3-5 mm). Analysis of the nosZ, and amoA gene libraries also indicated the stratification of denitrifiers and nitrifiers, with their highest diversity being in the anoxic and oxic sediment layers, respectively. These results indicated that redox-stratification can affect the distribution of bacterial communities in sandy reef sediments.

  11. Microplastics elutriation from sandy sediments: A granulometric approach.

    Science.gov (United States)

    Kedzierski, Mikaël; Le Tilly, Véronique; Bourseau, Patrick; Bellegou, Hervé; César, Guy; Sire, Olivier; Bruzaud, Stéphane

    2016-06-15

    Although relatively easy to extract in the marine environment, microplastics are very difficult to recover when they are trapped in sediments. The elutriation column is one of the best tools currently available for extracting plastics from sediment, but with a high sand recovery yield. This study aims to address the following questions: (i) is it possible to use a sedimentological approach to limit the sand recovery? (ii) does the extraction velocity of the sand and plastic particles vary according to density and granulometry? (iii) what is the relative recovery efficiency obtained for dense polymer particles mixed with marine sand? Based on a new granulometric classification, different plastic particle-size fractions are defined. Their extraction velocities are experimentally determined on particles of sediment and different plastics (PA, PVC). The particle recovery experiments indicate that it is possible to extract >90% of dense plastic particles in cases of negligible sand recovery. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Sediment impacts on marine sponges.

    Science.gov (United States)

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

    2015-05-15

    Changes in sediment input to marine systems can influence benthic environments in many ways. Sponges are important components of benthic ecosystems world-wide and as sessile suspension feeders are likely to be impacted by changes in sediment levels. Despite this, little is known about how sponges respond to changes in settled and suspended sediment. Here we review the known impacts of sedimentation on sponges and their adaptive capabilities, whilst highlighting gaps in our understanding of sediment impacts on sponges. Although the literature clearly shows that sponges are influenced by sediment in a variety of ways, most studies confer that sponges are able to tolerate, and in some cases thrive, in sedimented environments. Critical gaps exist in our understanding of the physiological responses of sponges to sediment, adaptive mechanisms, tolerance limits, and the particularly the effect of sediment on early life history stages. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. The effect of the dominant polychaete Scolelepis squamata on nematode colonisation in sandy beach sediments: An experimental approach

    Science.gov (United States)

    Maria, Tatiana F.; Esteves, André M.; Vanaverbeke, Jan; Vanreusel, Ann

    2011-09-01

    The effect of an abundant sandy beach polychaete, Scolelepis squamata, on the colonisation of defaunated sediments by marine nematodes indicates that sandy beach fauna can be partially controlled by biological interactions within and across size groups. Experimental cores, equipped with windows allowing infaunal colonisation, were filled with defaunated sandy beach sediment containing two different treatments with and without S. squamata. These cores were inserted into microcosms filled with sediment with indigenous meiofauna collected from the field. The treatments were incubated in the laboratory at ambient temperature and salinity for 2, 7, 14 and 21 days, in order to follow the colonisation process of the defaunated sediments by the indigenous nematode fauna over time. Nematodes initially colonised both treatments, with abundances of up to 10% of the densities in the control; after 2 weeks, nematode densities in the cores without S. squamata surpassed the control densities. Nematode assemblages in both treatments were not species rich, and also differed in composition from the natural assemblages. The most successful colonising species, Enoplolaimus litoralis, was rare in the surrounding sediment, suggesting that colonisation was determined by species-specific characteristics such as body size, motility and feeding strategy. Initially the presence of macrofauna did not affect the nematode community composition, but after 2 weeks of the experiment, the presence of the polychaete seemed to facilitate the earlier establishment of non-opportunistic species.

  14. Muddy marine sediments are gels

    Science.gov (United States)

    Dorgan, K. M.; Clemo, W. C.; Barry, M. A.; Johnson, B.

    2016-02-01

    Marine sediments cover 70% of the earth's surface, are important sites of carbon burial and nutrient regeneration, and provide habitat for diverse and abundant infaunal communities. The majority of these sediments are muds, in which bioturbation affects sediment structure and geochemical gradients. How infaunal activites result in particle mixing depends on the mechanical properties of muddy sediments. At the scale of burrowing animals, muds are elastic solids. Animals move through these elastic muds by extending crack-shaped burrows by fracture. The underlying mechanism driving this elasticity, however, has not been explicitly illustrated. Here, we test the hypothesis that the elastic behavior of muddy sediments is disrupted by removal of organic material by measuring fracture toughness and stiffness of manipulated and control sediments. Our results indicate that the mechanical responses of sediments to forces are governed by the muco-polymeric matrix of organic material. Similar effects of organic material oxidation were not observed in sands, indicating a clear mechanical distinction between fine- and coarse-grained sediments. Muddy sediments are gels, not fluids or granular materials, and models of how sediments respond to forces imposed by, e.g., organisms, gases, and ambient water should explicitly consider the role of organic material.

  15. 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

  16. A laboratory experiment of intact polar lipid degradation in sandy sediments

    Directory of Open Access Journals (Sweden)

    J. Logemann

    2011-09-01

    Full Text Available Intact polar lipids (IPLs are considered biomarkers for living biomass. Their degradation in marine sediments, however, is poorly understood and complicates interpretation of their occurrence in geological samples. To investigate the turnover of IPLs, a degradation experiment with anoxic sandy sediments from the North Sea was conducted. Intact cells of two organisms that do not naturally occur in North Sea sediments were chosen as IPL sources: (i Saccharomyces cerevisiae, representative for ester-bound acyl lipids that also occur in Bacteria, and (ii the archaeon Haloferax volcanii, representative for ether-bound isoprenoid lipids. Surprisingly, IPLs with phosphoester-bound head groups showed approximately the same degradation rate as IPLs with glycosidic head groups. Furthermore, the results indicate a relatively fast degradation of S. cerevisiae IPLs with ester-bound moieties (analogs of bacterial membrane lipids and no significant degradation of archaeal IPLs with ether-bound moieties. Pore water and 16S rRNA-based DGGE analysis showed only a minor influence of the IPL source on microbial metabolism and community profiles. Due to our results, the IPL-based quantification of Archaea and Bacteria should be interpreted with caution.

  17. Importance of phytodetritus and microphytobenthos for heterotrophs in a shallow subtidal sandy sediment

    NARCIS (Netherlands)

    Evrard, V.; Huettel, M.; Cook, P.L.M.; Soetaert, K.; Heip, C.H.R.; Middelburg, J.J.

    2012-01-01

    The relative importance of allochthonous phytodetritus deposition and autochthonous microphytobenthos (MPB) production for benthic consumers in an organic carbon (C-org)-poor sandy sediment was assessed using a C-13-stable isotope natural abundance study combined with a dual C-13-tracer addition

  18. Remote Sensing Technique for Geoacoustic Characterization of Heterogeneous Marine Sediments

    National Research Council Canada - National Science Library

    Ivakin, Anatoliy N

    2006-01-01

    .... The specific scientific tasks of this project were: (1) to develop inversion algorithms for estimating the sediment grain size distribution of coarse fractions in sandy sediments based on a recently developed inclusion scattering" model, (2...

  19. Hydrodynamic Stresses Driving Pore Pressure Changes in Sandy Coastal Sediments

    Science.gov (United States)

    1997-09-30

    nature of the sediment properties (Mei and Foda , 1981, Bennett et al. 1982, 1992a and b). A serious deficiency exist in the available in situ data bases...Holland. SEAPROBE Technical Report, 36p. Mei, C.C. and M.A. Foda ., 1981. Wave-Induced Responses in a Fluid-Filled Poro-Elastic Solid with a Free

  20. Bibliography of sandy beaches and sandy beach organisms on the African continent

    CSIR Research Space (South Africa)

    Bally, R

    1986-01-01

    Full Text Available This bibliography covers the literature relating to sandy beaches on the African continent and outlying islands. The bibliography lists biological, chemical, geographical and geological references and covers shallow marine sediments, surf zones off...

  1. 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.

  2. Dispersion of Sound in Marine Sediments

    Science.gov (United States)

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Dispersion of Sound in Marine Sediments N. Ross...our understanding of the interaction of sound with the ocean bottom is the frequency dependence of sound speed and attenuation in marine sediments...The long term goals of this research project are related to the investigation of dispersion of sound speed and attenuation at low frequencies (< 2

  3. Sandy sediment and the bioavailability of 17β-trenbolone to adult female fathead minnows.

    Science.gov (United States)

    Jessick, Ashley M; Skolness, Sarah; Kolok, Alan S

    2014-03-01

    Recent studies have detected bioavailable steroids in sediment, however, the mechanism by which these compounds become bioavailable is not completely understood. In this study, two experiments were conducted using a double aquarium system that allowed female fathead minnows to be exposed to sandy sediments without direct contact. In the first experiment, natural sediment from the Elkhorn River (Nebraska, USA) was spiked with 17β-trenbolone. Both the fish in direct contact with the sediment as well as the fish excluded from direct contact experienced significant reductions in the hepatic expression of two estrogen-responsive genes, vitellogenin and estrogen receptor α, indicating molecular defeminization. The natural sediment contained particles ranging in size from sand to clay and it was possible that the fish in experiment 1 were being exposed to trenbolone associated with the very fine particles. The sandy sediment was sieved for experiment 2, and only the particles larger than 250 μm were used. In addition, the experiment was conducted at two different Tb concentrations (1× and 10×). Furthermore nuptial tubercles, a biomarker of exposure to a masculinizing androgen, were also evaluated in the females used in experiment 2. For tubercle number and vtg expression, significant results were obtained from a two-way ANOVA due to Tb concentration, but not tank location or interaction term (location vs. concentration). For ERα expression, results were found in response to Tb concentration and tank location, but not the interaction term. Overall the results from these studies suggest that the primary route of exposure of sediment-associated trenbolone to fish is through ventilation of free compound, rather than ingestion or direct contact with the sediments. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Influence of Trypaea australiensis population density on benthic metabolism and nitrogen dynamics in sandy estuarine sediment: A mesocosm simulation

    Science.gov (United States)

    Jordan, Mark A.; Welsh, David T.; Dunn, Ryan J. K.; Teasdale, Peter R.

    2009-02-01

    Laboratory mesocosm incubations were undertaken to investigate the influence of natural densities of the thalassinidean shrimp, Trypaea australiensis (marine yabby) on sediment oxygen demand (SOD), inorganic nutrient fluxes, and the N-cycle processes of nitrification, denitrification and dissimilatory nitrate reduction to ammonium (DNRA). Mesocosms (~ 0.1 m 2 × 55 cm deep) of sieved, natural T. australiensis inhabited sands were continually flushed with fresh seawater and pre-incubated for two weeks prior to being assigned to one of three treatments; control (no additions), low yabby density (40 T. australiensis m - 2 ) or high yabby density (80 T. australiensis m - 2 ). Thereafter, SOD and sediment-water column inorganic nutrient fluxes were determined periodically over a 38 day period. On the final day rates of denitrification and dissimilatory nitrate reduction to ammonium (DNRA) were also determined using the 15N-isotope pairing technique. Yabbies consistently and significantly ( p water column nitrate concentration. Indeed, nitrate reduction processes became an increasingly unimportant element with increasing yabby density with for example, N 2 generated by coupled nitrification-denitrification representing 11.5, 5.2 and 2.8% of the total inorganic-N recycled to the water column in the control, low density and high density yabby treatments, respectively. Overall, the major influence of T. australiensis in the studied low organic matter content, sandy sediments was to enhance coupling between the benthic and pelagic systems through increased rates of inorganic nitrogen regeneration in the sediment and enhanced export of this nitrogen to the water column. Our results also suggest that the influences of organisms such as T. australiensis which form deep, extensive and complex burrow systems where irrigation rates differ greatly between different burrow sections, may be more complex than those recorded for infauna which form simple U-shaped burrows. Additionally

  5. A new method for measuring bioturbation rates in sandy tidal flat sediments based on luminescence dating

    DEFF Research Database (Denmark)

    Madsen, Anni T.; Murray, Andrew S.; Jain, Mayank

    2011-01-01

    The rates of post-depositional mixing by bioturbation have been investigated using Optically Stimulated Luminescence (OSL) dating in two sediment cores (BAL2 and BAL5), retrieved from a sandy tidal flat in the Danish part of the Wadden Sea. A high-resolution chronology, consisting of thirty-six OSL...... ages with ages ranging between 2 ± 4 and 410 ± 20 years, is presented. Slices of sediment (1–2 cm thick) have been dated at least every 5 cm, and from these data mixing depths of 20 cm and 22 cm (BAL5 and BAL2, respectively) are readily identified. Below the mixing zone there is a significant decrease....... The significant change in sedimentation rates at BAL5 may indicate an offset in OSL age of up to 620 years. This paper uses a simple conceptual model for vertical mixing in which all the sediment excreted at the surface by lugworms is assumed to be completely reset before being re-incorporated in the sediment...

  6. A new method for measuring bioturbation rates in sandy tidal flat sediments based on luminescence dating

    DEFF Research Database (Denmark)

    Madsen, Anni Tindahl; Murray, Andrew S.; jain, A

    2011-01-01

    The rates of post-depositional mixing by bioturbation have been investigated using Optically Stimulated Luminescence (OSL) dating in two sediment cores (BAL2 and BAL5), retrieved from a sandy tidal flat in the Danish part of the Wadden Sea. A high-resolution chronology, consisting of thirty-six OSL...... ages with ages ranging between 2 4 and 410 20 years, is presented. Slices of sediment (1e2 cm thick) have been dated at least every 5 cm, and from these data mixing depths of 20 cm and 22 cm (BAL5 and BAL2, respectively) are readily identified. Below the mixing zone there is a significant decrease....... The significant change in sedimentation rates at BAL5 may indicate an offset in OSL age of up to 620 years. This paper uses a simple conceptual model for vertical mixing in which all the sediment excreted at the surface by lugworms is assumed to be completely reset before being re-incorporated in the sediment...

  7. Comparison of wastewater-associated contaminants in the bed sediment of Hempstead Bay, New York, before and after Hurricane Sandy

    Science.gov (United States)

    Fisher, Shawn C.; Phillips, Patrick; Brownawell, Bruce J.; Browne, James

    2016-01-01

    Changes in bed sediment chemistry of Hempstead Bay (HB) have been evaluated in the wake of Hurricane Sandy, which resulted in the release of billions of liters of poorly-treated sewage into tributaries and channels throughout the bay. Surficial grab samples (top 5 cm) collected before and (or) after Hurricane Sandy from sixteen sites in HB were analyzed for 74 wastewater tracers and steroid hormones, and total organic carbon. Data from pre- and post-storm comparisons of the most frequently detected wastewater tracers and ratios of steroid hormone and of polycyclic aromatic hydrocarbon concentrations indicate an increased sewage signal near outfalls and downstream of where raw sewage was discharged. Median concentration of wastewater tracers decreased after the storm at sites further from outfalls. Overall, changes in sediment quality probably resulted from a combination of additional sewage inputs, sediment redistribution, and stormwater runoff in the days to weeks following Hurricane Sandy.

  8. Superstorm Sandy marine debris wash-ups on Long Island - What happened to them?

    Science.gov (United States)

    Swanson, R Lawrence; Lwiza, Kamazima; Willig, Kaitlin; Morris, Kaitlin

    2016-07-15

    Superstorm Sandy generated huge quantities of debris in the Long Island, NY coastal zone. However, little appears to have been washed offshore to eventually be returned to Long Island's beaches as marine debris wash-ups. Information for our analysis includes debris collection statistics, very high resolution satellite images, along with wind and sea level data. Rigorous debris collection efforts along with meteorological conditions following the storm appear to have reduced the likelihood of debris wash-ups. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Reactive iron in marine sediments

    Science.gov (United States)

    Canfield, Donald E.

    1989-01-01

    The influence of reactive iron oxides on sediment pore-water chemistry is considered in detail. A carefully calibrated extraction scheme is used to determine the depth distributions of reactive iron phases at two very different localities: the relatively iron-rich Mississippi Delta and the relatively iron-poor FOAM site in Long Island Sound. Closed system incubations are used to characterize the rates of reaction between sulfide and both naturally occurring and pure iron mineral phases. Rates of iron liberation to pore solution are measured in the presence and absence of sulfate reduction, and the origin of dissolved iron in organic-rich sediments is speculated upon.

  10. Acoustics of Porous Media Including Marine Sediments

    Science.gov (United States)

    1999-09-30

    Sessarego, Laboratoire de Mecanique et d’Acoustique, C.N.R.S., Marseille, has a laboratory-based experimental program on acoustic waves in sediments...Italian National Research Council, Rome, pp. 301- 306 (1998). - 4 - 7. M.J. Buckingham, “Theory of compressional and shear waves in fluid -like marine

  11. Surface sediments in the marsh-sandy land transitional area: sandification in the western Songnen Plain, China.

    Science.gov (United States)

    Yu, Xiaofei; Grace, Michael; Zou, Yuanchun; Yu, Xuefeng; Lu, Xianguo; Wang, Guoping

    2014-01-01

    The development of sandification process was studied, by monitoring the changes of sediment characteristics, at marsh-sandy land intersections in China's Songnen region. A series of sediment collection plates were deployed in the region; after one year, sediments in these plates were analyzed for changes of mass and chemical characteristics. The sediment flux and the sand content of the sediments decreased with the increasing longitudinal distance between the sampling site and the centre line of a sand dune. The mean sediment flux was 29 ± 14 kg m(-2) yr(-1) and 0.6 ± 0.3 kg m(-2) yr(-1) in the sandy land and marsh, respectively. Strong, positive correlations were found between the concentrations of organic matter, total nitrogen, P, Fe, Ti, V and Zr, all of which were also negatively correlated with the sand content. The concentrations of organic matter, total nitrogen, P, Fe, Ti, V and Zr in the marsh sediment samples were all significantly greater than the corresponding concentrations of the sandy land (pmarsh could be divided into three distinct zones. Sand expansion extended about 88 m into the marsh. The mean sand content in the sediments of the sandy land was 91% and then 64% in the marsh, which in turn was higher than that of marshes outside the influence of sandification, suggesting that the marsh in the marsh-sandy land transitional area has already undergone extensive sandification in the past. The study results provide information on the wetland's function of indicating and buffering the sandification process.

  12. Design of a marine sediment trap and accessories

    Digital Repository Service at National Institute of Oceanography (India)

    Janakiraman, G.; Fernando, V.; Venkatesan, R.; Rajaraman, V.S.

    The marine sediment trap and the mooring accessories were developed indigenously and were used successfully for the collection of settling sediments in the Arabian Sea The experience gained in using sediment trap and further improvements...

  13. MOBILIZATION AND CHARACTERIZATION OF COLLOIDS GENERATED FROM CEMENT LEACHATES MOVING THROUGH A SRS SANDY SEDIMENT

    Energy Technology Data Exchange (ETDEWEB)

    Li, D.; Roberts, K.; Kaplan, D.; Seaman, J.

    2011-09-20

    Naturally occurring mobile colloids are ubiquitous and are involved in many important processes in the subsurface zone. For example, colloid generation and subsequent mobilization represent a possible mechanism for the transport of contaminants including radionuclides in the subsurface environments. For colloid-facilitated transport to be significant, three criteria must be met: (1) colloids must be generated; (2) contaminants must associate with the colloids preferentially to the immobile solid phase (aquifer); and (3) colloids must be transported through the groundwater or in subsurface environments - once these colloids start moving they become 'mobile colloids'. Although some experimental investigations of particle release in natural porous media have been conducted, the detailed mechanisms of release and re-deposition of colloidal particles within natural porous media are poorly understood. Even though this vector of transport is known, the extent of its importance is not known yet. Colloid-facilitated transport of trace radionuclides has been observed in the field, thus demonstrating a possible radiological risk associated with the colloids. The objective of this study was to determine if cementitious leachate would promote the in situ mobilization of natural colloidal particles from a SRS sandy sediment. The intent was to determine whether cementitious surface or subsurface structure would create plumes that could produce conditions conducive to sediment dispersion and mobile colloid generation. Column studies were conducted and the cation chemistries of influents and effluents were analyzed by ICP-OES, while the mobilized colloids were characterized using XRD, SEM, EDX, PSD and Zeta potential. The mobilization mechanisms of colloids in a SRS sandy sediment by cement leachates were studied.

  14. 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...

  15. Contrasting effects of the polychaetes Marenzelleria viridis and Nereis diversicolor on benthic metabolism and solute transport in sandy coastal sediment

    DEFF Research Database (Denmark)

    Kristensen, Erik; Hansen, Tanja; Delefosse, Matthieu

    2011-01-01

    The contrasting effects of the invasive Marenzelleria viridis and the native Nereis diversicolor on benthic metabolism, partitioning of reaction pathways and distribution of inorganic porewater (C and N) solutes in homogenized sandy sediment were investigated experimentally over a period of 1 mo.......-dwelling polychaete in shallow coastal sediments will probably affect the biogeochemical functioning and ecological stability of the ecosystem. Among other things, organisms tolerant to sulfide are likely to be favored at the expense of more sensitive species....

  16. Wave and sediment dynamics along a shallow subtidal sandy beach inhabited by modern stromatolites.

    Science.gov (United States)

    Eckman, J E; Andres, M S; Marinelli, R L; Bowlin, E; Reid, R P; Aspden, R J; Paterson, D M

    2008-01-01

    To help define the habitat of modern marine stromatolites, wave-dominated flow and sediment transport were studied in the shallow subtidal region (1-2 m depth) along the slightly concave, windward face of Highborne Cay, Exuma, Bahamas - the only face of the cay that includes a population of stromatolites concentrated near the region of highest curvature of the beach. Wave energy impacting this island's most exposed beach was driven by local wind forcing which increases largely in response to the passage of atmospheric disturbances that typically affect the region for periods of a few days. Although some wave energy is almost always noted (maximum horizontal orbital speeds at the bottom are rarely Stromatolites, which are largely restricted to the shoreward side of a shallow platform reef, are sheltered by the reef beyond which wave speeds are one to four times higher (depending on tidal stage). Moreover, stromatolite populations are predominantly found along a region of this wave-exposed beach that experiences comparatively reduced wave energy because of the curved morphology of the island's face. Maximum wave speeds are 1.4 to 2 times higher along more northern sections of the beach just beyond the locus of stromatolite populations. A quantitative model of sediment transport was developed that accurately predicted accumulation of suspended sediment in sediment traps deployed in the shallow subtidal zone along this beach. This model, coupled with in situ wave records, indicates that gross rates of suspended sediment deposition should be two to three times higher northward of the main stromatolite populations. Regions of the beach containing stromatolites nevertheless should experience significant rates of gross suspended sediment deposition averaging 7-10 g cm(-2) day(-1) ( approximately 4-6 cm day(-1)). Results suggest that one axis of the habitat of modern marine stromatolites may be defined by a comparatively narrow range of flow energy and sediment transport

  17. Carotenoid diagenesis in a marine sediment

    Science.gov (United States)

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

    1977-01-01

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

  18. Sandy inland braidplain deposition with local aeolian sedimentation in the lower and middle parts of the buntsandstein and sandy coastal braidplain deposition in the topmost zechstein in the sudetes (Lower Silesia, Poland)

    Science.gov (United States)

    Mroczkowski, Jerzy; Mader, Detlef

    restricted to a narrow range between the end members of a pebbly to sandy highly-braided stream system representing the coarser facies tracts and a sandy to pebbly moderately-braided river complex representing the finer facies tracts. The evolution in time and space is characterized by mainly random lateral shifting and vertical overlapping of two coexistent fluvial styles within an irregularly zoned braidplain lacking organization of the two facies realms into discrete belts. Palaeogeographically, the two end members of the spectrum of fluvial style may sometimes even be equivalent to a more proximal and a more distal facies belt. In terms of position within the general depositional framework of the whole Mid-European Triassic Basin, the inland braidplain of the Sudetes is situated within the transitional reach from the proximal zone to the medial zone I. Based on comparative interpretation of the topmost Zechstein beds in the region of Chemsko and Kochanów in the Intra Sudetic Trough, the overall depositional history in parts of the area comprises the passage from marine carbonate sedimentation via a narrow coastal fluvial braidplain with pedogenesis in semi-arid climate at the margin of the Zechstein sea to an extensive inland fluvial braidplain with probably local aeolian deposition in almost arid climate in the Buntsandstein. Comparative evaluation of the marginal Zechstein in the Intra Sudetic Trough in Lower Silesia in Poland and of the marginal Lower Muschelkalk in Luxembourg allows to assess the Buntsandstein succession near the borders of the basin as an overall symmetrical major clastic wedge prograding into the depositional area with retreat of the Zechstein ocean and retrograding from the basin with transgression of the Muschelkalk sea. In view of a general model of continental sedimentation, the alluvial marginal belt of the Zechstein sea in Lower Silesia in Poland represents a predecessor, and the fluvial marginal seam of the Muschelkalk ocean in Luxembourg

  19. The microbial control of phosphorus fluxes in marine sediments

    NARCIS (Netherlands)

    Steenbergh, A.K.

    2012-01-01

    This thesis explores how microorganisms affect the release of the key nutrient phosphorus from marine sediments. A detailed understanding of the controls on regeneration of phosphorus from sediments is important because phosphorus availability in surface waters can regulate primary productivity.

  20. Electrokinetic strengthening of a marine sediment using intermittent current

    National Research Council Canada - National Science Library

    Micic S; Shang J.Q; Lo K.Y; Lee Y.N; Lee S.W

    2001-01-01

    An experimental program on electrokinetic strengthening of a marine sediment using intermittent current was conducted on a high-salinity marine clay recovered from a land reclamation site on the Korean coast...

  1. Predicting the denitrification capacity of sandy aquifers from shorter-term incubation experiments and sediment properties

    Directory of Open Access Journals (Sweden)

    W. Eschenbach

    2013-02-01

    Full Text Available Knowledge about the spatial variability of denitrification rates and the lifetime of denitrification in nitrate-contaminated aquifers is crucial to predict the development of groundwater quality. Therefore, regression models were derived to estimate the measured cumulative denitrification of aquifer sediments after one year of incubation from initial denitrification rates and several sediment parameters, namely total sulphur, total organic carbon, extractable sulphate, extractable dissolved organic carbon, hot water soluble organic carbon and potassium permanganate labile organic carbon.

    For this purpose, we incubated aquifer material from two sandy Pleistocene aquifers in Northern Germany under anaerobic conditions in the laboratory using the 15N tracer technique. The measured amount of denitrification ranged from 0.19 to 56.2 mg N kg−1 yr−1. The laboratory incubations exhibited high differences between non-sulphidic and sulphidic aquifer material in both aquifers with respect to all investigated sediment parameters. Denitrification rates and the estimated lifetime of denitrification were higher in the sulphidic samples. For these samples, the cumulative denitrification measured during one year of incubation (Dcum(365 exhibited distinct linear regressions with the stock of reduced compounds in the investigated aquifer samples. Dcum(365 was predictable from sediment variables within a range of uncertainty of 0.5 to 2 (calculated Dcum(365/measured Dcum(365 for aquifer material with a Dcum(365 > 20 mg N kg−1 yr−1. Predictions were poor for samples with lower Dcum(365, such as samples from the NO3 bearing groundwater zone, which includes the non-sulphidic samples, from the upper part of both aquifers where denitrification is not sufficient to

  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. 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

  4. Sampling Design and Enumeration Statistics for Bacteria Extracted from Marine Sediments

    OpenAIRE

    Montagna, Paul A.

    1982-01-01

    The spatial and temporal distributions of marine bacteria were studied at both a muddy and a sandy subtidal site in North Inlet, S.C. The sampling design was hierarchical, since subsampling (by a dilution series) of the sediments was necessary to count bacterial cells using acridine orange epifluoresence microscopy. The cell count data fit a log-normal distribution. The abundance of bacteria was 1011 g−1 (dry weight) of mud and 109 g−1 (dry weight) of sand. Variance component analyses demonst...

  5. Acoustic Wave Dispersion and Scattering in Complex Marine Sediment Structures

    Science.gov (United States)

    2015-09-30

    Acoustic wave dispersion and scattering in complex marine sediment structures Charles W. Holland The Pennsylvania State University Applied...shear waves on dispersion in marine sediments . The first step will be development of the theory. WORK COMPLETED A brief summary of the work...propagation and scattering in the seabed. OBJECTIVES The objectives are to advance understanding of 1) the nature and mechanisms leading to sediment

  6. Trophic network model of exposed sandy coast: Linking continental and marine water ecosystems

    Science.gov (United States)

    Razinkovas-Baziukas, Artūras; Morkūnė, Rasa; Bacevičius, Egidijus; Gasiūnaitė, Zita Rasuolė

    2017-08-01

    A macroscopic food web network for the exposed sandy coastal zone of the south-eastern Baltic Sea was reconstructed using ECOPATH software to assess the matter and energy balance in the ecosystem. The model incorporated 40 living functional groups representing the Baltic Sea coastal system of Lithuania during the first decade of 21rst century. The overall pedigree index of our model was relatively high (0.66) as much of the input data originated from the study area. The results indicate net heterotrophy of the coastal zone due to strong influences from the nearby river - lagoon system (Curonian Lagoon). The majority of fish species and waterbirds were present in the coastal system on a seasonal basis and their migrations contributed to heterotrophic conditions. Among fish, the freshwater stragglers possibly contribute to the reversal of flow in biomass and energy from the coastal zone to the river-lagoon system. Top predators such as breeding and wintering piscivorous waterbirds and large pike-perch were identified as keystone species. There was a clear negative balance for the biomass of small marine pelagic fishes such as smelt, sprat and Baltic herring which represent the main prey items in this system.

  7. Long distance electron transmission in marine sediment

    DEFF Research Database (Denmark)

    Risgaard-Petersen, Nils; Nielsen, Lars Peter

    suggest that the electron conductance is mediated by microorgan-isms. The spatial separation of electron and proton donors and acceptors has major impacts on element cycling by redox processes, pH balances, mineral dissolution/precipitations, and electromigration of ions. The sepa-ration of redox...... processes leads to formation of electrical fields, which modifies ion transport. The local proton producing and proton consuming half reactions induces pH extremes that accelerate dissolution of iron sul-phides and calcium carbonates in anoxic layers and promotes the formation of Mg-calcite and iron oxides...... in 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....

  8. Marine Microbial Gene Abundance and Community Composition in Response to Ocean Acidification and Elevated Temperature in Two Contrasting Coastal Marine Sediments

    Directory of Open Access Journals (Sweden)

    Ashleigh R. Currie

    2017-08-01

    Full Text Available Marine ecosystems are exposed to a range of human-induced climate stressors, in particular changing carbonate chemistry and elevated sea surface temperatures as a consequence of climate change. More research effort is needed to reduce uncertainties about the effects of global-scale warming and acidification for benthic microbial communities, which drive sedimentary biogeochemical cycles. In this research, mesocosm experiments were set up using muddy and sandy coastal sediments to investigate the independent and interactive effects of elevated carbon dioxide concentrations (750 ppm CO2 and elevated temperature (ambient +4°C on the abundance of taxonomic and functional microbial genes. Specific quantitative PCR primers were used to target archaeal, bacterial, and cyanobacterial/chloroplast 16S rRNA in both sediment types. Nitrogen cycling genes archaeal and bacterial ammonia monooxygenase (amoA and bacterial nitrite reductase (nirS were specifically targeted to identify changes in microbial gene abundance and potential impacts on nitrogen cycling. In muddy sediment, microbial gene abundance, including amoA and nirS genes, increased under elevated temperature and reduced under elevated CO2 after 28 days, accompanied by shifts in community composition. In contrast, the combined stressor treatment showed a non-additive effect with lower microbial gene abundance throughout the experiment. The response of microbial communities in the sandy sediment was less pronounced, with the most noticeable response seen in the archaeal gene abundances in response to environmental stressors over time. 16S rRNA genes (amoA and nirS were lower in abundance in the combined stressor treatments in sandy sediments. Our results indicated that marine benthic microorganisms, especially in muddy sediments, are susceptible to changes in ocean carbonate chemistry and seawater temperature, which ultimately may have an impact upon key benthic biogeochemical cycles.

  9. Marine Microbial Gene Abundance and Community Composition in Response to Ocean Acidification and Elevated Temperature in Two Contrasting Coastal Marine Sediments.

    Science.gov (United States)

    Currie, Ashleigh R; Tait, Karen; Parry, Helen; de Francisco-Mora, Beatriz; Hicks, Natalie; Osborn, A Mark; Widdicombe, Steve; Stahl, Henrik

    2017-01-01

    Marine ecosystems are exposed to a range of human-induced climate stressors, in particular changing carbonate chemistry and elevated sea surface temperatures as a consequence of climate change. More research effort is needed to reduce uncertainties about the effects of global-scale warming and acidification for benthic microbial communities, which drive sedimentary biogeochemical cycles. In this research, mesocosm experiments were set up using muddy and sandy coastal sediments to investigate the independent and interactive effects of elevated carbon dioxide concentrations (750 ppm CO2) and elevated temperature (ambient +4°C) on the abundance of taxonomic and functional microbial genes. Specific quantitative PCR primers were used to target archaeal, bacterial, and cyanobacterial/chloroplast 16S rRNA in both sediment types. Nitrogen cycling genes archaeal and bacterial ammonia monooxygenase (amoA) and bacterial nitrite reductase (nirS) were specifically targeted to identify changes in microbial gene abundance and potential impacts on nitrogen cycling. In muddy sediment, microbial gene abundance, including amoA and nirS genes, increased under elevated temperature and reduced under elevated CO2 after 28 days, accompanied by shifts in community composition. In contrast, the combined stressor treatment showed a non-additive effect with lower microbial gene abundance throughout the experiment. The response of microbial communities in the sandy sediment was less pronounced, with the most noticeable response seen in the archaeal gene abundances in response to environmental stressors over time. 16S rRNA genes (amoA and nirS) were lower in abundance in the combined stressor treatments in sandy sediments. Our results indicated that marine benthic microorganisms, especially in muddy sediments, are susceptible to changes in ocean carbonate chemistry and seawater temperature, which ultimately may have an impact upon key benthic biogeochemical cycles.

  10. Observed gas hydrate morphologies in marine sediment

    Energy Technology Data Exchange (ETDEWEB)

    Holland, M.; Schultheiss, P.; Roberts, J.; Druce, M. [Geotek Ltd., Daventry, Northamptonshire (United Kingdom)

    2008-07-01

    The morphology of gas hydrate in marine sediments determines the basic physical properties of the sediment-hydrate matrix and provides information regarding the formation of gas hydrate deposits, and the nature of the disruption that will occur on dissociation. Small-scale morphology is useful in estimating the concentrations of gas hydrate from geophysical data. It is also important for predicting their response to climate change or commercial production. Many remote techniques for gas hydrate detection and quantification depend on hydrate morphology. In this study, morphology of gas hydrate was examined in HYACINTH pressure cores from recent seagoing expeditions. Visual and infrared observations from non-pressurized cores were also used. The expeditions and pressure core analysis were described in detail. This paper described the difference between two types of gas hydrate morphologies, notably pore-filling and grain-displacing. Last, the paper addressed the impact of hydrate morphology. It was concluded that a detailed morphology of gas hydrate is an essential component for a full understanding of the past, present, and future of any gas hydrate environment. 14 refs., 4 figs.

  11. A new model of marine sediment compression

    Science.gov (United States)

    Martin, Kylara; Wood, Warren

    2017-11-01

    Marine sediments cover two-thirds of the earth, and porosity (or void ratio) is a major controlling parameter in virtually every model of seafloor properties, including strength, sound speed, hydrology, thermal conductivity, and electrical resistivity. Our new model of void ratio (e) is based on the proportional void ratio, [ep = (e -er) / (e0 -er)], where e0 is the depositional maximum at the sea floor, and er is the minimum residual void ratio at depth. We assume the values of e0 and er are inherent characteristics of the sediment type. Our model further defines the compression index Cc to be the square root of the proportional void ratio (Cc (e) =(ep) 1 / 2). This new formulation establishes a direct relation between void ratio and effective stress: e =(e0 -er) - 1[log10 ⁡ (σ0 / σ) + 2 (e0 -er) ] 2 / 4 +er and exhibits several advantages over previous models that we demonstrate with compression test data from the Gulf of Mexico and Nankai Trough.

  12. The role of sediment compaction and groundwater withdrawal in local sea-level rise, Sandy Hook, New Jersey, USA

    Science.gov (United States)

    Johnson, Christopher S.; Miller, Kenneth G.; Browning, James V.; Kopp, Robert E.; Khan, Nicole S.; Fan, Ying; Stanford, Scott D.; Horton, Benjamin P.

    2018-02-01

    The rate of relative sea-level (RSL) rise at Sandy Hook, NJ (4.0 ± 0.5 mm/yr) was higher than The Battery, NY (3.0 ± 0.3 mm/yr) from 1900 to 2012 despite being separated by just 26 km. The difference cannot be explained by differential glacial isostatic adjustment (GIA; 1.4 ± 0.4 and 1.3 ± 0.4 mm/yr RSL rise, respectively) alone. We estimate the contribution of sediment compaction to subsidence at Sandy Hook using high-resolution grain size, percent organic matter, and porosity data from three upper Quaternary (≤13,350 cal yr) cores. The organic matter content (<2%) is too low to contribute to local subsidence. However, numerical modeling of the grain size-depth-age-porosity relationship indicates that compaction of deglacial silts likely reduced the column thickness by 10-20% over the past 13,350 cal yrs. While compaction rates were high immediately after the main silt deposition (13,350-13,150 cal yrs BP), rates decreased exponentially after deposition to an average 20th century rate of 0.16 mm/yr (90% Confidence Interval (C.I.), 0.06-0.32 mm/yr). The remaining ∼0.7 mm/yr (90% C.I. 0.3-1.2 mm/yr) difference in subsidence between Sandy Hook and The Battery is likely due to anthropogenic groundwater withdrawal. Historical data from Fort Hancock wells (2 km to the southeast of the Sandy Hook tide gauge) and previous regional work show that local and regional water extraction lowered the water levels in the aquifers underlying Sandy Hook. We suggest that the modern order of contribution to subsidence (highest to lowest) appears to be GIA, local/regional groundwater extraction, and compaction of thick Quaternary silts.

  13. Benthic solute exchange and carbon mineralization in two shallow subtidal sandy sediments: Effect of advective pore-water exchange

    DEFF Research Database (Denmark)

    Cook, Perran L. M.; Wenzhofer, Frank; Glud, Ronnie N.

    2007-01-01

    We conducted four field campaigns to evaluate benthic O-2 consumption and the effect of advective pore-water flow in nearshore permeable sediments in the North Sea and Baltic Sea. Advective pore-water transport had a marked effect on the benthic exchange of O-2 and TCO2 in benthic chamber...... of O-2 distribution across ripples, and also deep subsurface O-2 pools, being observed. Mineralization pathways were predominantly aerobic when benthic mineralization rates were low and advective pore-water flow high as a result of well-developed sediment topography. By contrast, mineralization...... proceeded predominantly through sulfate reduction when benthic mineralization rates were high and advective pore-water flow low as a result of poorly developed topography. Previous studies of benthic mineralization in shallow sandy sediments have generally ignored these dynamics and, hence, have overlooked...

  14. Sediment-associated microdiversity within the Marine Group I Crenarchaeota.

    Science.gov (United States)

    Durbin, Alan M; Teske, Andreas

    2010-10-01

    Although oligotrophic, abyssal marine sediments cover most of the sea bottom, previous investigations of microbial diversity have primarily focused on organic-rich, anoxic sediments of continental margins. In contrast, abyssal open-ocean sediments are oxidized and contain limiting organic substrate concentrations. This study examines the archaeal diversity of oligotrophic, oxic and nitrate-reducing marine sediments and oxic bottom water in the South Pacific Gyre. 16S rDNA clone library analysis identified phylogenetically distinct lineages of the Marine Group I (MG-I) Crenarchaeota in oxidized sediment that are different from those in bottom water. Thus, the sediment habitat selects for different MG-I lineages, within short vertical distances of a few centimetres. © 2010 Society for Applied Microbiology and Blackwell Publishing Ltd.

  15. Application of a Coupled Ocean Wave Sediment Transport Modeling System to Investigate Morphological Changes during Hurricane Sandy.

    Science.gov (United States)

    Warner, J. C.; List, J. H.; Safak, I.; Liste, M.; Schwab, W. C.

    2016-02-01

    Barrier islands provide a means of defense against large storm impacts. While a vast majority of studies focus on the subaeial areas of barrier islands, a significant component of barrier island geologic framework is submerged. Understanding how barrier islands respond to storms requires a thorough investigation of the complete inner-shelf to surf-zone region. Hurricane Sandy impacted the US east coast in 2012 and was one of the most destructive storms in US history with impacts including flooding, coastal erosion, dune overtopping, breaching. Here we evaluate the oceanographic processes and morphological changes during Hurricane Sandy on Fire Island, NY and the adjacent inner continental shelf using geophysical observations and numerical modeling. Geologic investigations of the seafloor in 2011 and 2014 demonstrate changes of seafloor morphology and modern sediment thickness revealing up to 450 m of lateral movement of sedimentary features and deposition at depths up to 30 m. Physical processes responsible for these morphological changes were investigated using a coupled ocean-wave-sediment modeling system (COAWST) with grid refinement to simulate oceanographic conditions on a regional 5-km grid along the entire US east coast, with increased resolution of 700 m in the NY bight, 100 m along Fire Island, and 5 m at the breach formed due to Hurricane Sandy. Model results identify maximum surge of up to 3 m, surface currents up to 2 m/s, and wave heights up to 8 m. Sediment redistribution along Fire Island showed erosional patterns consistent with geologic observations. Modeling advancements using an infragravity wave component (InWave) identify key aspects of barrier island response during the storm. Total storm water levels along Fire Island are shown to be a combination of surge, tidal, and infragravity signal. During the peak of the storm total water level and wave action was able to create a breach. Models results are compared to field observations.

  16. Harvesting energy from the marine sediment--water interface.

    Science.gov (United States)

    Reimers, C E; Tender, L M; Fertig, S; Wang, W

    2001-01-01

    Pairs of platinum mesh or graphite fiber-based electrodes, one embedded in marine sediment (anode), the other in proximal seawater (cathode), have been used to harvest low-level power from natural, microbe established, voltage gradients at marine sediment-seawater interfaces in laboratory aquaria. The sustained power harvested thus far has been on the order of 0.01 W/m2 of electrode geometric area but is dependent on electrode design, sediment composition, and temperature. It is proposed that the sediment/anode-seawater/cathode configuration constitutes a microbial fuel cell in which power results from the net oxidation of sediment organic matter by dissolved seawater oxygen. Considering typical sediment organic carbon contents, typical fluxes of additional reduced carbon by sedimentation to sea floors ocean.

  17. Geomechanical, Hydraulic and Thermal Characteristics of Deep Oceanic Sandy Sediments Recovered during the Second Ulleung Basin Gas Hydrate Expedition

    Directory of Open Access Journals (Sweden)

    Yohan Cha

    2016-09-01

    Full Text Available This study investigates the geomechanical, hydraulic and thermal characteristics of natural sandy sediments collected during the Ulleung Basin gas hydrate expedition 2, East Sea, offshore Korea. The studied sediment formation is considered as a potential target reservoir for natural gas production. The sediments contained silt, clay and sand fractions of 21%, 1.3% and 77.7%, respectively, as well as diatomaceous minerals with internal pores. The peak friction angle and critical state (or residual state friction angle under drained conditions were ~26° and ~22°, respectively. There was minimal or no apparent cohesion intercept. Stress- and strain-dependent elastic moduli, such as tangential modulus and secant modulus, were identified. The sediment stiffness increased with increasing confining stress, but degraded with increasing strain regime. Variations in water permeability with water saturation were obtained by fitting experimental matric suction-water saturation data to the Maulem-van Genuchen model. A significant reduction in thermal conductivity (from ~1.4–1.6 to ~0.5–0.7 W·m−1·K−1 was observed when water saturation decreased from 100% to ~10%–20%. In addition, the electrical resistance increased quasi-linearly with decreasing water saturation. The geomechanical, hydraulic and thermal properties of the hydrate-free sediments reported herein can be used as the baseline when predicting properties and behavior of the sediments containing hydrates, and when the hydrates dissociate during gas production. The variations in thermal and hydraulic properties with changing water and gas saturation can be used to assess gas production rates from hydrate-bearing deposits. In addition, while depressurization of hydrate-bearing sediments inevitably causes deformation of sediments under drained conditions, the obtained strength and stiffness properties and stress-strain responses of the sedimentary formation under drained loading conditions

  18. Advancing marine hydrokinetic turbine arrays towards large-scale deployments in sandy rivers: a laboratory study

    Science.gov (United States)

    Musa, Mirko; Hill, Craig; Guala, Michele

    2016-11-01

    A staggered array of twelve axial-flow marine hydrokinetic (MHK) turbine models was investigated at the St. Anthony Falls Laboratory under live-bed sediment transport conditions. In particular, the interaction between the MHK power plant and the complex migrating bedforms was monitored using a state-of-the-art high-resolution submersible laser scanning device able to provide spatio(x,y)-temporally(t) resolved channel bathymetry z(x,y,t). Results revealed both a local signature of each individual turbine and a cumulative array effect that extends farther from the site. Single turbine localized scour results from the blockage effect of the operating rotor and the consequent flow acceleration between the lower rotor tip and the erodible bed. The resultant shear stress enhancement around the device protects the turbine during extreme sediment transport conditions, ultimately preventing the blades from impacting the incoming bedforms. A turbine failure case was simulated to illustrate the consequence of such event, which can irreversibly bury and damage the turbine. Additionally, velocity and turbine performance estimates provided a preliminary description of the power plant energy output, revealing similar features already observed in experimental wind farm models. NSF Career Grant - Geophysical Flow Control, Dr. Michele Guala.

  19. Ice-proximal Marine Sedimentation in the Ross Sea during LGM: Ice-sheet and Ocean Interactions

    Science.gov (United States)

    Turetta, C.; Aghib, F. S.; Ferretti, P.; Barbante, C.

    2016-12-01

    We present preliminary results from a multi-proxy study of different cores from the Ross Sea, Antarctica. Thirty cores have been sampled at the Antarctic Marine Geology Research Facility (AMRF), Florida State University in order to discriminate different source areas and to reconstruct the depositional setting and related climate implications in a peculiar ice-proximal marine setting. Sediment characterizations, trace elements (TE) and rare earth elements (REEs) compositional analysis and evaluation about their source areas have been performed on sediment cores collected widespread in the Ross Sea area. Analysis of 72 samples from thirty cores was performed to determine total concentration of Li, Be, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Rb, Sr, Ag, Cd, Cs, Ba, Tl, Pb, Bi, Th, U, Y and REEs. This extensive geochemical characterization of cores from several sites in the Ross Sea, will allow to better define the sedimentary processes, to understand the evolution of the ice-proximal marine setting, to evaluate areas with different geochemical features related to different provenances. In particular REEs allow us to discriminate different source areas and to better define the ocean input in the sediment composition. Moreover, 17 sediment cores from Coulman High area collected along two transects were characterized in order to constrain sediment bulk composition, biogenic vs non-biogenic components and the related depositional setting. Sediments from the two transects show a completely different bulk composition, those from the Northern transect mainly consist of fine-grained sediments containing well-preserved biogenic carbonate remains. Sediments from the Southern cores mainly consist of dark greenish diatomaceous sandy mud containing abundant diatoms in fragments. Sedimentation along the two transects seems to reflect the extent of the ice sheets in an ice-proximal marine setting. REEs compositional analyses have confirmed different source regions, a

  20. 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...

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

    NARCIS (Netherlands)

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

    2011-01-01

    Recent studies have shown that ancient plankton DNA can be recovered from Holocene lacustrine and marine sediments, including from species that do not leave diagnostic microscopic fossils in the sediment record. Therefore, the analysis of this so-called fossil plankton DNA is a promising approach

  2. 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.

  3. Microbial diversity and stratification of South Pacific abyssal marine sediments.

    Science.gov (United States)

    Durbin, Alan M; Teske, Andreas

    2011-12-01

    Abyssal marine sediments cover a large proportion of the ocean floor, but linkages between their microbial community structure and redox stratification have remained poorly constrained. This study compares the downcore gradients in microbial community composition to porewater oxygen and nitrate concentration profiles in an abyssal marine sediment column in the South Pacific Ocean. Archaeal 16S rRNA clone libraries showed a stratified archaeal community that changed from Marine Group I Archaea in the aerobic and nitrate-reducing upper sediment column towards deeply branching, uncultured crenarchaeotal and euryarchaeotal lineages in nitrate-depleted, anaerobic sediment horizons. Bacterial 16S rRNA clone libraries revealed a similar shift on the phylum and subphylum level within the bacteria, from a complex community of Alpha-, Gamma- and Deltaproteobacteria, Actinobacteria and Gemmatimonadetes in oxic surface sediments towards uncultured Chloroflexi and Planctomycetes in the anaerobic sediment column. The distinct stratification of largely uncultured bacterial and archaeal groups within the oxic and nitrate-reducing marine sediment column provides initial constraints for their microbial habitat preferences. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  4. Grain-size Statistical Parameters of Sandy Sediment in Kuala Gigieng, Aceh Besar District

    OpenAIRE

    Purnawan, Syahrul; Haekal A. Haridhi; Setiawan, Ichsan; Marwantim,

    2015-01-01

    Study of sediment distribution at Kuala Gigieng was to assess the information of sediment related to the occurrence of hydro-oceanographic processes. The sediment samples were collected from nine stations using coring method. Granulometric method was used to analyze the grain size distributions. The results showed different sediment distribution patterns in each area at estuary Kuala Gigieng. The outer area of estuary indicated skewed to coarse grains, while at the inner area of estuary indic...

  5. 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.

  6. Chlorobiphenhyls in marine sediments: guidelines for determination

    National Research Council Canada - National Science Library

    Smedes, F; de Boer, J

    1998-01-01

    The analysis of chlorinated biphenyls in sediments generally includes extraction with organic solvents, clean-up, removal of sulphur, column fractionation and gas chromatographic separation, mostly...

  7. Controls on the barium isotope compositions of marine sediments

    Science.gov (United States)

    Bridgestock, Luke; Hsieh, Yu-Te; Porcelli, Donald; Homoky, William B.; Bryan, Allison; Henderson, Gideon M.

    2018-01-01

    The accumulation of barium (Ba) in marine sediments is considered to be a robust proxy for export production, although this application can be limited by uncertainty in BaSO4 preservation and sediment mass accumulation rates. The Ba isotope compositions of marine sediments could potentially record insights into past changes in the marine Ba cycle, which should be insensitive to these limitations, enabling more robust interpretation of sedimentary Ba as a proxy. To investigate the controls on the Ba isotope compositions of marine sediments and their potential for paleo-oceanographic applications, we present the first Ba isotope compositions results for sediments, as well as overlying seawater depth profiles collected in the South Atlantic. Variations in Ba isotope compositions of the sediments predominantly reflect changes in the relative contributions of detrital and authigenic Ba sources, with open-ocean sediments constraining the isotope composition of authigenic Ba to be δ138/134Ba ≈ + 0.1 ‰. This value is consistent with the average isotope composition inferred for sinking particulate Ba using simple mass balance models of Ba in the overlying water column and is hypothesized to reflect the removal of Ba from the upper water column with an associated isotopic fractionation of Δdiss-part 138/134Ba ≈ + 0.4 to +0.5. Perturbations to upper ocean Ba cycling, due to changes in export production and the supply of Ba via upwelling, should therefore be recorded by the isotope compositions of sedimentary authigenic Ba. Such insights will help to improve the reliable application of Ba accumulation rates in marine sediments as a proxy for past changes in export production.

  8. Bacterial communities in sediment of a Mediterranean marine protected area.

    Science.gov (United States)

    Catania, Valentina; Sarà, Gianluca; Settanni, Luca; Quatrini, Paola

    2017-04-01

    Biodiversity is crucial in preservation of ecosystems, and bacterial communities play an indispensable role for the functioning of marine ecosystems. The Mediterranean marine protected area (MPA) "Capo Gallo-Isola delle Femmine" was instituted to preserve marine biodiversity. The bacterial diversity associated with MPA sediment was compared with that from sediment of an adjacent harbour exposed to intense nautical traffic. The MPA sediment showed higher diversity with respect to the impacted site. A 16S rDNA clone library of the MPA sediment allowed the identification of 7 phyla: Proteobacteria (78%), Firmicutes (11%), Acidobacteria (3%), Actinobacteria (3%), Bacteroidetes (2%), Planctomycetes (2%), and Cyanobacteria (1%). Analysis of the hydrocarbon (HC)-degrading bacteria was performed using enrichment cultures. Most of the MPA sediment isolates were affiliated with Gram-positive G+C rich bacteria, whereas the majority of taxa in the harbour sediment clustered with Alpha- and Gammaproteobacteria; no Gram-positive HC degraders were isolated from the harbour sediment. Our results show that protection probably has an influence on bacterial diversity, and suggest the importance of monitoring the effects of protection at microbial level as well. This study creates a baseline of data that can be used to assess changes over time in bacterial communities associated with a Mediterranean MPA.

  9. [Actinobacterial diversity of marine sediment samples from Chile].

    Science.gov (United States)

    Jiang, Hong; Lin, Ru; Chen, Lujie; Lin, Hao; Nie, Yilei; Lian, Yunyang

    2010-07-01

    The aim of this study was to investigate actinobacterial diversity in Chilean marine sediments. Actinobacterial diversity in these sediments was investigated by selective isolation method, culture-independent method and phylogenetic analysis based on 16S rRNA gene sequences. Six selective media were used to isolate actinomycetes from sediment samples. The primers for the class Actinobacteria were used for Actinobacterial 16S rRNA gene amplification and then a clone library was constructed for the sediment sample btt. Twenty-two strains with different culture characteristics and 59 clones from sample btt were selected for 16S rRNA gene sequences analysis. To determine requirement for seawater each strain was grown on oatmeal agar prepared with deionized water and with seawater, respectively. Strains were screened for antibiotic activity against bacteria and fungi. In total 328 actinomycetes were obtained. Twenty-two strains which were selected belonged to Streptomyces, Micromonospora, Polymorphospora, Aeromicrobium and Brachybacterium. Fifty-nine clones (40 OTUs) were sequenced, and 60% OTUs belonged to Actinobacteridae, Acidimicrobidae and Rubrobacteridae. The other 40% OTUs, which formed several distinct clades in phylogenetic tree among phylum Actinobacteria may represent new taxonomical groups. 50% of the 47 sea water dependant strains and nineteen strains out of the above 22 strains exhibited antimicrobial activity. There was abundant actinobacterial diversity in the marine sediments of Chile, and the result implied that there were large numbers of unknown actinobacterial groups in the sediments. Actinomycetes from Chilean marine sediments had the potential of producing bioactive secondary metabolites.

  10. Occurrence and sorption properties of arsenicals in marine sediments

    DEFF Research Database (Denmark)

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

    2013-01-01

    in the Baltic Sea and other parts of the world. Existing data for on-site measurements of sorption coefficients (Kd) of arsenicals in marine and freshwater sediments show large variability from 1,000 L/kg. In this work, calculated sorption coefficients (Kd and Koc) for As(III+V) showed significant correlation...... in marine sediments when conditions are similar to the Baltic Sea. At locations with significant anthropogenic point sources or where the local geology contains volcanic rock and sulphide mineral deposits, there may be significantly elevated arsenic concentrations, and it is recommended to determine on...

  11. 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...

  12. Adherent bacteria in heavy metal contaminated marine sediments.

    Science.gov (United States)

    Gillan, David C; Pernet, Philippe

    2007-01-01

    The eubacterial communities adherent to sediment particles were studied in heavy metal contaminated coastal sediments. Six sampling sites on the Belgian continental plate and presenting various metal loads, granulometries, and organic matter content, were compared. The results indicated that the total microbial biomass (attached + free-living bacteria) was negatively correlated to HCl-extractable metal levels (pmarine sediments but that the ratio between attached and free living microorganisms is not affected. The composition of the eubacterial communities adherent to the fine fraction of the sediments (bacteria, was not related to the HCl extractable metal levels. Most of the 79 complete 16S rRNA sequences obtained from the attached microbial communities were classified in the gamma- and delta-Proteobacteria and in the CFB bacteria. A large proportion of the attached gamma-Proteobacterial sequences found in this study (56%) was included in the uncultivated GMS clades that are indigenous to marine sediments.

  13. Actinobacterial diversity from marine sediments collected in Mexico.

    Science.gov (United States)

    Maldonado, Luis A; Fragoso-Yáñez, Dulce; Pérez-García, Adriana; Rosellón-Druker, Judith; Quintana, Erika T

    2009-02-01

    Seventeen different media known to support the growth and isolation of members of the class Actinobacteria were evaluated as selective isolation media for the recovery of this microbial group from marine sediments samples collected in the Gulf of California and the Gulf of Mexico. A general selective isolation procedure was employed for six sediments and nearly 300 actinomycetes were recovered from the selective isolation plates. Full 16S rRNA gene sequencing revealed that the isolates belonged to several actinobacterial taxa, notably to the genera Actinomadura, Dietzia, Gordonia, Micromonospora, Nonomuraea, Rhodococcus, Saccharomonospora, Saccharopolyspora, Salinispora, Streptomyces, "Solwaraspora" and Verrucosispora. Previous works on marine sediments have been restricted to the isolation of members of the genera Micromonospora, Rhodococcus and Streptomyces. This study provides further evidence that Actinobacteria present in marine habitats are not restricted to the Micromonospora-Rhodococcus-Streptomyces grouping. Indeed, this first systematic study shows the extent of actinobacterial diversity that can be found in marine sediments collected in Mexico and probably, worldwide.

  14. Contaminated marine sediments: assessment and remediation

    National Research Council Canada - National Science Library

    National Research Council (U.S.). Committee on Contaminated Marine Sediments

    1989-01-01

    ... Marine Board Commission on Engineering and Technical Systems National Research Council National Academy Press Washington, D.C. 1989 i Copyrighttrue Please breaks inserted. are Page files. accidentally typesetting been have may original from the errors not typographic original retained, and from the created cannot be files XML from howeve...

  15. Anoxic microniches in marine sediments induced by aggregate settlement

    DEFF Research Database (Denmark)

    Lehto, Niklas; Glud, Ronnie N.; Nordi, Gunnvør á

    2014-01-01

    Spherical (*2 mm diameter) diatom (Skeletonema sp.) aggregates, representing analogues of ‘‘marine snow’’, were placed at the sediment–water interface of an experimental sediment system. Optode measurements showed that, after an initial lag period, oxygen concentrations within the aggregates...... experiments. The validated model was used to investigate how the size and reactivity of parcels of organic matter influence the formation of anoxic microniches at the sediment–water interface of typical deep-sea environments. As well as kOMM, the concentration of reactive organic matter in the aggregate, its...... a significant contribution to the denitrification occurring in a typical deep-sea sediment. This work suggests that anoxic microniches resulting from the settlement of marine aggregates may play an overlooked role for denitrification activities in deep-sea sediments....

  16. Terrestiral plant biopolymers in marine sediments

    Energy Technology Data Exchange (ETDEWEB)

    Gough, M.A.; Fauzi, R.; Mantoura, C. (Plymouth Marine Lab. (United Kingdom)); Preston, M. (Univ. of Liverpool (United Kingdom))

    1993-03-01

    The vascular land plant biopolymers lignin and cutin were surveyed in the surface sediments of coastal and open ocean waters by controlled alkaline CuO oxidation/reaction. Two contrasting oceanic regimes were studied: the northwest Mediterranean (NWM) Sea, which receives significant particulate terrigenous debris through riverine discharge; and the northeast Atlantic (NEA) Ocean, with poorly characterized terrestrial carbon inputs. In the NWM products of lignin and cutin co-occurred at all stations, elevated levels (ca. 0.5-3.0 mg lignin phenols/100 mg organic carbon; ca. 0.01-0.09 mg cutin acids/100 mg organic carbon) were observed for near-shore deltaic and shelf sediments. The influence of terrestrial land plant inputs extended across the shelf and through the slope to the abyssal plain, providing molecular evidence for advective offshore transfer of terrestrial carbon. Mass balance estimates for the basin suggest riverine inputs account for the majority of surface sedimentary ligin/cutin, most of which (>90%) is deposited on the shelf. Products of CuO oxidation of lignin and cutin were also detected in NEA surface sediments, at levels comparable to those observed for the NWM continental slope, and were detectable at low concentrations in the sediments of the abyssal plains (>4,000 m depth). While atmospheric deposition of lignin/cutin-derived material cannot be discounted in this open ocean system, lateral advective transfer of enriched shelf sediments is inferred as a possible transport process. A progressive enrichment in cutin-derived material relative to lignin was observed offshore, with evidence of an increase in the degree of oxidative alteration of lignin residues. Preliminary mass balance calculations applied to the global ocean margin suggest riverine sources of both particulate lignin and cutin are important and that most (>95%) deposition of recognizable land plant biopolymers occurs in shelf seas. 74 refs., 7 figs., 5 tabs.

  17. 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

  18. Eruption-related lahars and sedimentation response downstream of Mount Hood: Field guide to volcaniclastic deposits along the Sandy River, Oregon

    Science.gov (United States)

    Pierson, Tom C.; Scott, William E.; Vallance, James W.; Pringle, Patrick T.; O'Connor, Jim; Dorsey, Rebecca; Madin, Ian

    2009-01-01

    Late Holocene dome-building eruptions at Mount Hood during the Timberline and Old Maid eruptive periods resulted in numerous dome-collapse pyroclastic flows and lahars that moved large volumes of volcaniclastic sediment into temporary storage in headwater canyons of the Sandy River. During each eruptive period, accelerated sediment loading to the river through erosion and remobilization of volcanic fragmental debris resulted in very high sediment-transport rates in the Sandy River during rain- and snowmelt-induced floods. Large sediment loads in excess of the river's transport capacity led to channel aggradation, channel widening, and change to a braided channel form in the lowermost reach of the river, between 61 and 87 km downstream from the volcano. The post-eruption sediment load moved as a broad bed-material wave, which in the case of the Old Maid eruption took ~2 decades to crest 83 km downstream. Maximum post-eruption aggradation levels of at least 28 and 23 m were achieved in response to Timberline and Old Maid eruptions. In each case, downstream aggradation cycles were initiated by lahars, but the bulk of the aggradation was achieved by fluvial sediment transport and deposition. When the high rates of sediment supply began to diminish, the river degraded, incising the channel fills and forming progressively lower sets of degradational terraces. A variety of debris-flow, hyperconcentrated-flow, and fluvial (upper and lower flow regime) deposits record the downstream passage of the sediment waves that were initiated by these eruptions. The deposits also presage a hazard that may be faced by communities along the Sandy River when volcanic activity at Mount Hood resumes.

  19. Marine geotechnical data for North Pacific sediments

    Science.gov (United States)

    Richards, Adrian F.

    1978-01-01

    Geotechnical data from the published and unpublished literature are compiled in SI units and tabulated in a standardized format. Eight data sets are presented from a geographic area approximately bounded by 5° and 32° north latitude and 120° and 170° west longitude. The data exist in machine-readable form in the data bank of the Marine Geotechnical Laboratory, Lehigh University.

  20. A model for microbial phosphorus cycling in bioturbated marine sediments

    DEFF Research Database (Denmark)

    Dale, Andrew W.; Boyle, R. A.; Lenton, Timothy M.

    2016-01-01

    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...... 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...

  1. Photosynthesis as a Possible Source of Gas Bubbles in Shallow Sandy Coastal Sediments

    Science.gov (United States)

    2012-09-30

    clearly demonstrates that gas bubbles can be formed when photosynthesis by benthic microalgae causes pore water to become supersaturated with oxygen...We also collected sediment samples from the upper few mm of sand to identify the dominant taxa of benthic microalgae present. Although benthic...Jan Rines (Graduate School of Oceanography / University of Rhode Island = GSO/URI) to identify the benthic microalgae in the samples. Following the

  2. Impact of Ibrahim River on the spatial variation of coastal marine sediment characteristics

    Science.gov (United States)

    Ghsoub, Myriam; Fakhri, Milad; Courp, Thierry; Khalaf, Gaby; Buscail, Roselyne; Ludwig, Wolfgang

    2017-04-01

    In the aim to evaluate the impact of Ibrahim River on the environmental status of its coastal marine zone, sedimentological (grain size composition), geochemical (organic carbon, total nitrogen, total carbon, organic matter, calcium carbonate, organic and inorganic phosphate) biochemical (chlorophyll-a, pheopigments) and biological parameters (macro-invertebrates) of the sediment were analyzed and interpreted. Three sampling campaigns were executed using the scientific vessel CANA-CNRS on 26-4-2016, 20-6-2016 and 29-7-2016 successively. The samples were collected according to a middle horizontal transectat three different depths (10, 20, and 30 m).The grain size composition of the sediment was mainly composed of fine sand. The obtained values of organic matter ranged between 32 and 54 mg/g. The total nitrogen was between 0.006 and 0.014%. The percentage of calcium carbonate fluctuated between 20 and 30%. This situation may be attributed to the decomposition and the sinking of the shells and some aquatic organism such as Coccolithophores, foraminifers, gastropods and bivalves. Calcium carbonate may also have terrestrial origin related to the carbonated adjacent land and may be exported to the coastal area with the river inputs. The sediment of the studied area was richer in pheopigments (between 0.8 and 3 μg/g) than in chlorophyll-a (less than 0.4 μg/g) witnessing the presence of degraded material due to the high hydrodynamic conditions. Furthermore, the low values of chlorophyll-a witnessed the oligotrophy of the zone. The concentrations of total phosphate ranged between 97 and 148 μg/g. The dominance of the inorganic phosphate at all sampling points indicates that phosphorus is available for the producers, and that the studied area is less contaminated with anthropogenic discharges. This research project reveals the presence of gastropods, crustaceans and some polychaetes along the five studied stations. These groups are generally found in sandy bottoms

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

    Science.gov (United States)

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

    2011-09-01

    Recent studies have shown that ancient plankton DNA can be recovered from Holocene lacustrine and marine sediments, including from species that do not leave diagnostic microscopic fossils in the sediment record. Therefore, the analysis of this so-called fossil plankton DNA is a promising approach for refining paleoecological and paleoenvironmental information. However, further studies are needed to reveal whether DNA of past plankton is preserved beyond the Holocene. Here, we identified past eukaryotic plankton members based on 18S rRNA gene profiling in eastern Mediterranean Holocene and Pleistocene sapropels S1 (~9 ka), S3 (~80 ka), S4 (~105 ka), and S5 (~125 ka). The majority of preserved ~400- to 500-bp-long 18S rDNA fragments of microalgae that were studied in detail (i.e. from haptophyte algae and dinoflagellates) were found in the youngest sapropel S1, whereas their specific lipid biomarkers (long-chain alkenones and dinosterol) were also abundant in sediments deposited between 80 and 124 ka BP. The late-Pleistocene sediments mainly contained eukaryotic DNA of marine fungi and from terrestrial plants, which could have been introduced via the river Nile at the time of deposition and preserved in pollen grains. A parallel analysis of Branched and Isoprenoid Tetraethers (i.e. BIT index) showed that most of the organic matter in the eastern Mediterranean sediment record was of marine (e.g. pelagic) origin. Therefore, the predominance of terrestrial plant DNA over plankton DNA in older sapropels suggests a preferential degradation of marine plankton DNA. © 2011 Blackwell Publishing Ltd.

  4. 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

  5. Long-distance electron transport occurs globally in marine sediments

    Science.gov (United States)

    Burdorf, Laurine D. W.; Tramper, Anton; Seitaj, Dorina; Meire, Lorenz; Hidalgo-Martinez, Silvia; Zetsche, Eva-Maria; Boschker, Henricus T. S.; Meysman, Filip J. R.

    2017-02-01

    Recently, long filamentous bacteria have been reported conducting electrons over centimetre distances in marine sediments. These so-called cable bacteria perform an electrogenic form of sulfur oxidation, whereby long-distance electron transport links sulfide oxidation in deeper sediment horizons to oxygen reduction in the upper millimetres of the sediment. Electrogenic sulfur oxidation exerts a strong impact on the local sediment biogeochemistry, but it is currently unknown how prevalent the process is within the seafloor. Here we provide a state-of-the-art assessment of its global distribution by combining new field observations with previous reports from the literature. This synthesis demonstrates that electrogenic sulfur oxidation, and hence microbial long-distance electron transport, is a widespread phenomenon in the present-day seafloor. The process is found in coastal sediments within different climate zones (off the Netherlands, Greenland, the USA, Australia) and thrives on a range of different coastal habitats (estuaries, salt marshes, mangroves, coastal hypoxic basins, intertidal flats). The combination of a widespread occurrence and a strong local geochemical imprint suggests that electrogenic sulfur oxidation could be an important, and hitherto overlooked, component of the marine cycle of carbon, sulfur and other elements.

  6. 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.

  7. Post Preloading Creep Properties of Highly Compressible Harbor Marine Sediments

    Directory of Open Access Journals (Sweden)

    Franciscus Xaverius Toha

    2017-07-01

    Full Text Available A laboratory experimental research in creep behavior of soft clay marine sediments was done to investigate creep strain under reloading. A total of 52 oedometer tests were carried out with 16 slurry sediment samples subjected to cycles of unloading at preload removal pressure and reloading to higher design pressures. Common practice as well as more recent advanced methods of creep deformation analysis were used to refine the predictions. The study indicates that although preloading substantially reduces post construction creep, the analysis is very sensitive to creep indices at slight overconsolidation and the resulting creep may not be negligible at previously established limits of primary to secondary compression ratios.

  8. Visual assessment of redoxcline compared to electron potential in coastal marine sediments

    Science.gov (United States)

    Simone, Michelle; Grant, Jon

    2017-03-01

    A geochemical proxy often utilized in marine benthic health assessment is the depth of the apparent redox potential discontinuity (aRPD), a visual signature representing the transition from lighter oxidized to darker reduced sediments. Traditionally this boundary is defined by the redox potential discontinuity (RPD), a 0 mV isovolt measured by platinum electrodes. In order to verify the use of visual transitions as a proxy for electrochemical RPD, these measurements were compared in subtidal sandy muds (13.5 m depth) in coastal Nova Scotia, Canada. The apparent RPD was measured from sediment profile imagery (SPI) images and diver-retrieved cores. Pre-drilled cores with vertical holes allowed for the coupling of electrochemical and visual boundary measurements in the same sample. The mean discrepancy of the RPD is 0.6 ± 2.6 cm (mean ± maximum variation) above the aRPD depth. The Eh range at the aRPD, -14.94 ± 52.21 mV, encompassed the 0 mV isovolt, suggesting the aRPD can be applied as a sound proxy for the transition between redox states.

  9. Temporal variations in microbenthic metabolism and inorganic nitrogen fluxes in sandy and muddy sediments of a tidally dominated bay in the northern Wadden Sea

    Science.gov (United States)

    Kristensen, E.; Jensen, M. H.; Jensen, K. M.

    1997-12-01

    Factors controlling seasonal variations in benthic metabolism (O2 flux) and dissolved inorganic nitrogen (DIN) fluxes were examined during a 12-14 month period at three intertidal Wadden Sea stations. Since the flux measurements were made as small-scale laboratory core incubations, the results are primarily related to the microbenthic community (microalgae, bacteria, micro-, meio- and small macrofauna) and cannot be considered representative of the total benthic community in the Wadden Sea. Furthermore, it has to be emphasized that light intensity during day-time simulations were constant and saturating at all times. Benthic primary production and oxygen uptake appeared to be temperature dependent with a ‘seasonal Q10’ of 1.7-1.8 and 2.7-4.3, respectively. Inundation had no effect on oxygen fluxes as evidenced by similar sediment respiration with and without water cover. A stronger temperature dependence of primary production in muddy than in sandy sediment indicated that the overall control in the latter may be complex due to factors like macrofaunal grazing and nutrient availability. Benthic respiration may not be controlled by temperature alone, as sedimentary organic matter content correlated significantly with both temperature and benthic respiration. Annual gross primary production in high intertidal sandy sediment was 10 and 50% higher than in low intertidal sandy and muddy sediments, respectively. Since annual benthic community respiration was 2 times higher in muddy than sandy sediments, the annual net primary production was about 0 in the former and 17-19 mol C m-2 yr-1 in the latter. However, heterotrophic contribution by larger faunal components as well as removal of organic carbon by waves and tidal currents, which are not included here, may balance the budget at the sandy stations. There was no or only weak relationships between (light and dark) DIN exchange and factors like temperature, sedimentary organic content, and oxygen fluxes. Factors

  10. Coal and deodorizer residues in marine sediments - contaminants or pollutants?

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, P.M.; Downie, J.; Maynard, A.; Taylor, L.A. [EVS Consultants Ltd., North Vancouver, BC (Canada)

    1996-05-01

    Sediment studies around the diffuser of a relatively untreated major marine municipal sewage discharge indicated that 1,4-dichlorobenzene (1,4-DCB) and polycyclic aromatic hydrocarbons (PAHs) were among the contaminants of concern. Subsequent investigations revealed that elevated PAH concentrations were due to the shipwreck of a collier in the 1890s and were apparently not bioavailable. Coal is a common contaminant in marine and freshwater sediments and may be responsible, in some cases, for high PAH contaminant concentrations not resulting in pollution (i.e. biological effects) and can also affect total organic carbon measurements and normalization. Little information exists regarding 1,4-DCB, whose main source to sewage appears to be toilet block deodorizers and which appears to be useful marker of the extent of contamination for untreated sewage discharges. Correlative analyses suggest it is pollutant, but this remains to be confirmed by experimental testing.

  11. Draft genome sequence of the marine actinomycete Streptomyces sulphureus L180, isolated from marine sediment.

    Science.gov (United States)

    Zhao, Xinqing; Geng, Xiang; Chen, Chao; Chen, Liangyu; Jiao, Wence; Yang, Chao

    2012-08-01

    Marine-derived actinobacteria are rich sources of valuable natural products and industrial enzymes for biotechnology applications. The marine-derived Streptomyces sulphureus strain L180 was isolated from the marine sediment in a sea cucumber farm at a depth of about 10 m in Dalian, China, and its 16S rRNA gene sequence was determined to have the highest identity to that of Streptomyces sulphureus NRRL B-1627(T) (99.65%). Here, we report the draft genome sequence of this strain.

  12. Draft Genome Sequence of the Marine Actinomycete Streptomyces sulphureus L180, Isolated from Marine Sediment

    OpenAIRE

    Zhao, Xinqing; Geng, Xiang; Chen, Chao; Chen, Liangyu; Jiao, Wence; Yang, Chao

    2012-01-01

    Marine-derived actinobacteria are rich sources of valuable natural products and industrial enzymes for biotechnology applications. The marine-derived Streptomyces sulphureus strain L180 was isolated from the marine sediment in a sea cucumber farm at a depth of about 10 m in Dalian, China, and its 16S rRNA gene sequence was determined to have the highest identity to that of Streptomyces sulphureus NRRL B-1627T (99.65%). Here, we report the draft genome sequence of this strain.

  13. 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...

  14. Spheroidal Carbonaceous Particles (SCPs) as Chronological Markers in Marine Sediments

    Science.gov (United States)

    Thornalley, D.; Rose, N.; Oppo, D.

    2016-12-01

    Spheroidal carbonaceous particles (SCPs) are a component of fly-ash, the particulate by-product of industrial high-temperature combustion of coal and fuel-oil that is released to the atmosphere with flue-gases. They are morphologically distinct and have no natural sources making them unambiguous markers of contamination from these anthropogenic sources. In naturally accumulating archives, SCPs may be used as a chronological tool as they provide a faithful record of industrial emissions and deposition. While the timing of the first presence of SCP in the 19th century, and the observed sub-surface peak are dependent on factors such as sediment accumulation rates and local industrial history, a rapid increase in SCP inputs in the mid-20thcentury appears to be a global signal corresponding to an acceleration in global electricity demand following the Second World War and the use of fuel-oil in electricity production at an industrial scale for the first time. While this approach has been widely used in lake sediments, it has not been applied to marine sediments, although there is great potential. Improved dating of 19th-20th century marine sediments has particular relevance for developing reconstructions of recent multi-decadal climate and ocean variability, and for studies that aim to place 20thcentury climate change within the context of the last millennium. Here, we present data from three sediment cores from the continental slope south of Iceland to demonstrate the temporal and spatial replicability of the SCP record in the marine environment and compare these data with cores taken from more contaminated areas off the coast of the eastern United States. The improved age model constraints provided by the analysis of SCPs has enabled a more accurate assessment of the timing of recent abrupt climate events recorded in these archives and has thus improved our understanding of likely causal climate mechanisms.

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

    Science.gov (United States)

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

    2009-04-01

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

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

    Science.gov (United States)

    Martens, C. S.

    1985-01-01

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

  17. 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......-, Fe(III) oxides, or MnO2 are available as potential electron acceptors. In chemical experiments, FeS2 and FeS were oxidized by MnO2 but not with NO3- or amorphous Fe(III) oxide (Schippers and Jørgensen, 2001). Here we also show that in experiments with anoxic sediment slurries, a dissolution of tracer......-marked (FeS2)-Fe-55 occurred with MnO2 but not with NO3- or amorphous Fe(III) oxide as electron acceptor. To study a thermodynamically possible anaerobic microbial FeS, and FeS oxidation with NO3- or amorphous Fe(III) oxide as electron acceptor, more than 300 assays were inoculated with material from several...

  18. Microbial Communities from Methane Hydrate-Bearing Deep Marine Sediments

    Energy Technology Data Exchange (ETDEWEB)

    Reed, David William; Fujita, Yoshiko; Delwiche, Mark Edmond; Blackwelder, David Bradley; Colwell, Frederick Scott; Uchida, T.

    2002-08-01

    Microbial communities in cores obtained from methane hydrate-bearing deep marine sediments (down to more than 300 m below the seafloor) in the forearc basin of the Nankai Trough near Japan were characterized with cultivation-dependent and -independent techniques. Acridine orange direct count data indicated that cell numbers generally decreased with sediment depth. Lipid biomarker analyses indicated the presence of viable biomass at concentrations greater than previously reported for terrestrial subsurface environments at similar depths. Archaeal lipids were more abundant than bacterial lipids. Methane was produced from both acetate and hydrogen in enrichments inoculated with sediment from all depths evaluated, at both 10 and 35°C. Characterization of 16S rRNA genes amplified from the sediments indicated that archaeal clones could be discretely grouped within the Euryarchaeota and Crenarchaeota domains. The bacterial clones exhibited greater overall diversity than the archaeal clones, with sequences related to the Bacteroidetes, Planctomycetes, Actinobacteria, Proteobacteria, and green nonsulfur groups. The majority of the bacterial clones were either members of a novel lineage or most closely related to uncultured clones. The results of these analyses suggest that the microbial community in this environment is distinct from those in previously characterized methane hydrate-bearing sediments.

  19. Distribution, community assembly and metabolic potential of sulfate-reducing microorganisms in marine sediments

    DEFF Research Database (Denmark)

    Jochum, Lara

    2017-01-01

    and strategy for subsisting under sulfate and organic carbon limitation in marine sediments is poorly understood. In this thesis I have studied the distribution, community assembly and metabolic potential of SRM populating in the coastal marine sediments of Aarhus Bay. Firstly, I investigated how SRM...... by decreasing availability of organic matter and sulfate with sediment depth. SRM are a taxonomically and metabolically diverse group and populate both surface and subsurface marine sediments. Large subgroups of environmental SRM are uncultured, particularly in marine subsurface sediments, and their physiology...... communities in marine sediment change across the vertical depth profile of sediment cores by next generation sequencing of a functional marker gene indicative of SRM. The abundance, distribution and identity of SRM at different depths were assessed and the results compared with geochemical data. Thereby, I...

  20. 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 (marine environments harbour highly diverse actinobacterial communities, many of which appear to be novel, uncultured species.

  1. An integrated approach to the toxicity assessment of Irish marine sediments: validation of established marine bioassays for the monitoring of Irish marine sediments.

    Science.gov (United States)

    Macken, Ailbhe; Giltrap, Michelle; Foley, Barry; McGovern, Evin; McHugh, Brendan; Davoren, Maria

    2008-10-01

    This paper describes the ecotoxicological evaluation of marine sediments from three sites around Ireland representative of a range of contaminant burdens. A comprehensive assessment of potential sediment toxicity requires the consideration of multiple exposure phases. In addition to the evaluation of multi-exposure phases the use of a battery of multi-trophic test species has been advocated by a number of researchers as testing of single or few organisms may not detect toxicants with a specific mode of action. The Microtox solid phase test (SPT) and the 10-d acute amphipod test with Corophium volutator were used to assess whole sediment toxicity. Porewater and elutriates were assessed with the Microtox acute test, the marine prasinophyte Tetraselmis suecica, and the marine copepod Tisbe battagliai. Solvent extracts were assayed with the Microtox and T. battagliai acute tests. Alexandra Basin was identified as the most toxic site according to all tests, except the Microtox SPT which identified the Dunmore East site as being more toxic. However, it was not possible to correlate the observed ecotoxicological effects with a specific and/or class of contaminants based on sediment chemistry alone. Therefore porewaters found to elicit significant toxicity (Dunmore East and Alexandra Basin) with the test battery were selected for further TIE assessment with T. battalgiai and the Microtox system. The results of this study have important implications for risk assessment in estuarine and coastal waters in Ireland, where, at present the monitoring of sediment and water quality is predominantly reliant on chemical analysis alone.

  2. Biological test method: Acute test for sediment toxicity using marine or estuarine amphipods

    National Research Council Canada - National Science Library

    McLeay, D. J; Sprague, John B

    1992-01-01

    Methods recommended by Environment Canada for performing 10-day tests for sediment toxicity, using one or more of the following species of marine or estuarine sediment-burrowing amphipods, are described in this report...

  3. Factors influencing organic carbon preservation in marine sediments

    Science.gov (United States)

    Canfield, D. E.

    1994-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Burgess, R.M.; McKinney, R.A. (Science Applications International Corp., Narragansett, RI (United States)); Schweitzer, K.A. (Chemical Waste Management, Inc., Dartmouth, MA (United States)); Phelps, D.K. (Environmental Protection Agency, Narragansett, RI (United States))

    1993-01-01

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

  6. Recovery of Bacillus thuringiensis from marine sediments of Japan.

    Science.gov (United States)

    Maeda, M; Mizuki, E; Nakamura, Y; Hatano, T; Ohba, M

    2000-06-01

    Marine sediments from a Japanese bay were examined for the occurrence of Bacillus thuringiensis. Of 1313 colonies belonging to the Bacillus cereus/B. thuringiensis group, 22 (1.7%) were allocated to B. thuringiensis. Marine isolates of B. thuringiensis consisted of heterogeneous multiple H serogroups; 10 isolates were assigned to the eight serovars (kurstaki, sumiyoshiensis, sotto, aizawai, darmstadiensis, thompsoni, neoleonensis, and higo); two motile isolates failed to react with the reference antisera; and the others were serologically untestable. Insecticidal activities were associated with two kurstaki isolates (toxic to both Lepidoptera and Diptera) and a higo isolate (Diptera-specific). None of the parasporal inclusion proteins of the 22 isolates exhibited in vitro cytotoxic activity against two vertebrate cells, sheep erythrocytes and HeLa cells. All B. thuringiensis isolates had no halophilism, although seawater-based medium supported their growth, sporulation, and formation of parasporal inclusions.

  7. Trace metal seasonal variations in Texas marine sediments

    Science.gov (United States)

    Holmes, C.W.

    1986-01-01

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

  8. Nonlinear acoustics of water-saturated marine sediments

    DEFF Research Database (Denmark)

    Jensen, Leif Bjørnø

    1976-01-01

    , are given a critical evaluation with emphasis put on limitations in their applicability. B/A-values of some marine sediments—quartz medium and fine sand, silt, and clay—characterizing the seabed of the Danish archipelago and measured in our laboratory by means of the test methods discussed are given...... and are compared with nonlinear acoustic qualities determined through small-scale explosion tests performed in the sediments. Sources leading to possible deviations between test results arising from prospective in situ measurements and from measurements carried out under laboratory conditions are discussed....

  9. 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...

  10. The Light-Field of Microbenthic Communities - Radiance Distribution and Microscale Optics of Sandy Coastal Sediments Rid A-1977-2009

    DEFF Research Database (Denmark)

    KUHL, M.; JØRGENSEN, BB

    1994-01-01

    , the light field became diffuse with a forward-biased angular light distribution. A few millimeters into the sediment surface, attenuation coefficients of field radiance, irradiance, and scalar irradiance became identical and independent of depth, indicating that the light field approached an asymptotic...... relative to vertically incident collimated light in rinsed quartz sand and in a coastal sandy sediment colonized by microalgae. Upwelling and downwelling components of irradiance and scalar irradiance were calculated from the radiance distributions. Calculated total scalar irradiance agreed well...... radiance distribution. Comparison of light fields in wet and dry quartz sand showed that the lower refractive index of air than of water caused a more forward-biased scattering in wet sand. Light penetration was therefore deeper and surface irradiance reflectance was lower in wet sand than in dry sand...

  11. Sediment dynamics of a sediment-starved, open-marine marsh embayment: Waccasassa Bay, Florida

    Science.gov (United States)

    Wood, Nathan J.; Hine, Albert C.

    2003-01-01

    Although the Big Bend region of Florida's Gulf of Mexico coast is considered sediment-starved, the open marine marshes that characterize the area are keeping pace with sea level rise. Waccasassa Bay, an embayment within this region, also contains unique subtidal mudbanks that thicken with increasing proximity to embayment head, while the remainder of the bayfloor is characterized by exposed carbonate bedrock or by a thin veneer of sediment. Hydro- dynamic data sets were collected to determine the primary sedimentary processes within Waccasassa Bay capable of creating such geomorphic features. Data suggest that the embayment is a flood-dominated system influenced primarily by semi-diurnal tides with flood-stage intensification towards the river-mouth. Subtidal mudbanks are believed to be the result of tidal time-velocity asymmetries and the convergence of sediment transport pathways. Flood dominance for potential bedload transport suggests a gradual infilling of the bay interior for the short time scale of this study. With no mechanism for seaward transport, Waccasassa Bay can be considered a sediment sink for the remainder of the Big Bend re

  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. Properties of bricks produced from Greenlandic marine sediments

    DEFF Research Database (Denmark)

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

    2015-01-01

    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...... miniature bricks) of both pellets and miniature bricks were investigated and the results were compared with ASTM requirements for building bricks to classify their resistance to damage by freezing. The study of miniature bricks showed that the water absorption was too high after 24 h of submersion in cold......, the major mineral phases were seen to be dominated by quarts and feldspar. Chemical investigations of MS showed low contents of both sulphur and carbon, whereas an unexpectedly high content of chlorine was found. A laboratory-scale study was made on fired brick pellets (d ∼20 mm, h ∼ 3 mm), and of fired...

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

    Science.gov (United States)

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

    2003-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Carr, R.S.; Biedenbach, J.M. [National Biological Service, Corpus Christi, TX (United States). Marine Ecotoxicology Research Station; Long, E.R. [NOAA, Seattle, WA (United States); MacDonald, D.D. [MacDonald Environmental Sciences Ltd., Ladysmith, British Columbia (Canada)

    1995-12-31

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

  16. Heavy mineral analysis for assessing the provenance of sandy sediment in the San Francisco Bay Coastal System

    Science.gov (United States)

    Wong, Florence L.; Woodrow, Donald L.; McGann, Mary

    2013-01-01

    Heavy or high-specific gravity minerals make up a small but diagnostic component of sediment that is well suited for determining the provenance and distribution of sediment transported through estuarine and coastal systems worldwide. By this means, we see that surficial sand-sized sediment in the San Francisco Bay Coastal System comes primarily from the Sierra Nevada and associated terranes by way of the Sacramento and San Joaquin Rivers and is transported with little dilution through the San Francisco Bay and out the Golden Gate. Heavy minerals document a slight change from the strictly Sierran-Sacramento mineralogy at the confluence of the two rivers to a composition that includes minor amounts of chert and other Franciscan Complex components west of Carquinez Strait. Between Carquinez Strait and the San Francisco Bar, Sierran sediment is intermingled with Franciscan-modified Sierran sediment. The latter continues out the Gate and turns southward towards beaches of the San Francisco Peninsula. The Sierran sediment also fans out from the San Francisco Bar to merge with a Sierran province on the shelf in the Gulf of the Farallones. Beach-sand sized sediment from the Russian River is transported southward to Point Reyes where it spreads out to define a Franciscan sediment province on the shelf, but does not continue southward to contribute to the sediment in the Golden Gate area.

  17. Assessing the impact of Hurricanes Irene and Sandy on the morphology and modern sediment thickness on the inner continental shelf offshore of Fire Island, New York

    Science.gov (United States)

    Schwab, William C.; Baldwin, Wayne E.; Denny, Jane F.

    2016-01-15

    This report documents the changes in seabed morphology and modern sediment thickness detected on the inner continental shelf offshore of Fire Island, New York, before and after Hurricanes Irene and Sandy made landfall. Comparison of acoustic backscatter imagery, seismic-reflection profiles, and bathymetry collected in 2011 and in 2014 show that sedimentary structures and depositional patterns moved alongshore to the southwest in water depths up to 30 meters during the 3-year period. The measured lateral offset distances range between about 1 and 450 meters with a mean of 20 meters. The mean distances computed indicate that change tended to decrease with increasing water depth. Comparison of isopach maps of modern sediment thickness show that a series of shoreface-attached sand ridges, which are the dominant sedimentary structures offshore of Fire Island, migrated toward the southwest because of erosion of the ridge crests and northeast-facing flanks as well as deposition on the southwest-facing flanks and in troughs between individual ridges. Statistics computed suggest that the modern sediment volume across the about 81 square kilometers of common sea floor mapped in both surveys decreased by 2.8 million cubic meters, which is a mean change of –0.03 meters, which is smaller than the resolution limit of the mapping systems used.

  18. Extraction of bioavailable contaminants from marine sediments: an approach to reducing toxicity using adsorbent parcels.

    Science.gov (United States)

    Goodsir, Freya; Fisher, Tom T; Barry, Jon; Bolam, Thi; Nelson, Leah D; Rumney, Heather S; Brant, Jan L

    2013-07-15

    This paper demonstrates an approach to reducing acute toxicity in marine sediments using adsorbent parcels. Acute toxicity tests were carried using the marine amphipod Corophium volutator. Marine sediments were spiked with two know contaminants tributyltin and naphthalene and then treated with adsorbent parcels containing either amberlite XAD4 or activated carbon. Results showed that both types of adsorbent parcels were effective in reducing acute toxicity, not only within spiked sediments containing naphthalene and/or tributyltin, but also in an environmental field samples form an expected contaminated site. Adsorbent parcels such as these could provide a practical approach to remediate areas of contaminated sediment within marine environments. Furthermore adsorbents can be used as an identification tool for problematic contaminants using a toxicity identification evaluation approach. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

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

    National Research Council Canada - National Science Library

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

    2015-01-01

    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...

  20. Targeted search for actinomycetes from near-shore and deep-sea marine sediments

    Science.gov (United States)

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

    2013-01-01

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

  1. Foraminiferal constituent in marine sediments - A parameter in some coastal engineering problems

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G.A.P.

    Foraminifera, among other microorganisms, form a major constituent of marine sediments and their composition is directly related to the nature of the substrate in which they are entombed. Past and the present data indicate that the size, test...

  2. Marine and terrigenous lipids in southeast atlantic sediments (leg 175) as paleoenvironmental indicators: initial results

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Schefuss, E.; Versteegh, G.J.M.; Jansen, J.H.F.

    2001-01-01

    Lipid compositions of sediments recovered during Ocean Drilling Program Leg 175 in the eastern South Atlantic reflect a variety of oceanographic and climatological environments. Most of the identified lipids can be ascribed to marine sources, notably haptophytes,

  3. Effects of marine snow and muddy terrigenous sediments on the survival of hard coral recruits

    OpenAIRE

    Fabricius, K. E.; Wild, C.; Wolanski, E.; Abele, Doris

    2003-01-01

    Sedimentation is a major cause of mortality in scleractinian coralrecruits. In this study, we compared the effects of muddy coastalsediments, with and without enrichment by "marine snow" on thesurvivorship of recruits of the hard coral Acropora willisae. Transparentexopolymer particles (TEP) were measured as characteristiccomponents of marine snow using a staining method (Passow&Alldredge1995). Four-week old recruits were exposed to (i) muddy coastal sediments, (ii) TEP, (iii) TEP-enriched mu...

  4. Streptomyces pharmamarensis sp. nov. isolated from a marine sediment.

    Science.gov (United States)

    Carro, Lorena; Zúñiga, Paz; de la Calle, Fernando; Trujillo, Martha E

    2012-05-01

    A Gram-stain-positive actinobacterium, strain PM267(T), was isolated from a marine sediment sample in the Mediterranean Sea. The novel strain produced extensively branched substrate and aerial hyphae that carried spiral spore chains. Substrate and aerial mycelia were cream-white and white, respectively. Diffusible pigments were not observed. 16S rRNA gene sequence analysis revealed that strain PM267(T) belonged to the genus Streptomyces and shared a gene sequence similarity of 97.1 % with Streptomyces artemisiae YIM 63135(T) and Streptomyces armeniacus JCM 3070(T). Values <97 % were obtained with other sequences representing members of the genus Streptomyces. The cell wall peptidoglycan contained ll-diaminopimelic acid. MK-9(H(8)) was the major menaquinone. The phospholipid pattern included phosphatidylethanolamine as diagnostic lipid (type II). Major fatty acids found were iso- and anteiso- fatty acids. The G+C content of the DNA was 71.2 mol%. The strain was halotolerant and was able to grow in the presence of 9 % (w/v) NaCl (with an optimum of 2 %). On the basis of these results and additional physiological data obtained in the present study, strain PM267(T) represents a novel species within the genus Streptomyces for which the name Streptomyces pharmamarensis sp. nov. is proposed (type strain PM267(T)  = CECT 7841(T)  = DSM 42032(T)).

  5. 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.

  6. Linking Arenicola marina irrigation behavior to oxygen transport and dynamics in sandy sediments

    DEFF Research Database (Denmark)

    Timmermann, Karen; Banta, Gary T.; Glud, Ronnie Nøhr

    2007-01-01

    concentration in the burrow was high (80% air saturation) and oxygen was detected at distances up to 0.7 mm from the burrow wall. Volume specific oxygen consumption rates calculated from measured oxygen profiles were up to 4 times higher for sediments surrounding worm burrows as compared to surface sediments....... Model results indicated that oxygen consumption also was higher in the feeding pocket/funnel compared to the activity in surface sediments. An oxygen budget revealed that 49% of the oxygen pumped into the burrow during lugworm irrigation was consumed by the worm itself while 23% supported the diffusive...

  7. Integrated hazard, risk and impact assessment of tropical marine sediments from Tema Harbour (Ghana).

    Science.gov (United States)

    Botwe, Benjamin O; De Schamphelaere, Kristine; Schipper, Cor A; Teuchies, Johannes; Blust, Ronny; Nyarko, Elvis; Lens, Piet N L

    2017-06-01

    The potential ecological hazard, risk and impact of tropical marine sediments from the Tema Harbour (Greater Accra, Ghana) was investigated by integrating Corophium volutator and Hediste diversicolor whole-sediment toxicity bioassays with data on the metals (Cd, Pb, Cr, Ni, Cu, Zn and As) concentrations of the sediments. The whole-sediment toxicity bioassay results showed that sediments of the Tema Harbour are potentially hazardous to marine benthic invertebrates. C. volutator exhibited a higher vulnerability to the sediment toxicity than H. diversicolor, although the latter showed higher biota-sediment accumulation factors for the investigated metals. Statistically significant correlations were observed between C. volutator mortality and sediment Cd concentration (r = 0.84, p < 0.05; n = 6) and between H. diversicolor mortality and sediment Cu concentration (r = 0.94, p < 0.05; n = 5). Comparison of metal concentrations with international action levels for contaminated sediment disposal indicates that the Tema Harbour sediments contain potentially hazardous concentrations of Cu and Zn. This study shows that sediments from the Tema Harbour are not suitable for disposal at sea without remediation. There is, therefore, a need to improve environmental management and regulate the disposal of dredged material originating from the Tema Harbour. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Evaluation of the potential for using Greenlandic marine sediments for brick production

    DEFF Research Database (Denmark)

    Belmonte, Louise Josefine; Bertelsen, Ida Maria Gieysztor

    2016-01-01

    Fine grained marine sediments from near the Greenlandic towns of Ilulissat, Kangerlussuaq and Sisimiut were assessed as raw materials for local production of building bricks. The assessment included both analysis of the sediment characteristics and physical properties of miniature test brick...

  9. Diversity and characterization of culturable fungi from marine sediment collected from St. Helena Bay, South Africa

    CSIR Research Space (South Africa)

    Mouton, M

    2012-08-01

    Full Text Available origins. It has not been proven whether these fungi merely survive the harsh environmental conditions presented by the ocean sediment, as opposed to playing an active role in this ecological niche. During this study, marine sediment was collected from St...

  10. Depth distribution and assembly of sulfate-reducing microbial communities in marine sediments of Aarhus Bay

    DEFF Research Database (Denmark)

    Jochum, Lara M; Chen, Xihan; Lever, Mark A

    2017-01-01

    Most sulfate-reducing microorganisms (SRM) present in subsurface marine sediments belong to uncultured groups only distantly related to known SRM and it remains unclear how changing geochemical zones and sediment depth influence their community structure. We mapped the community composition and a...

  11. 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

  12. 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...

  13. 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...

  14. Google Earth-Based Grand Tours of the World's Ocean Basins and Marine Sediments

    Science.gov (United States)

    St John, K. K.; De Paor, D. G.; Suranovic, B.; Robinson, C.; Firth, J. V.; Rand, C.

    2016-12-01

    The GEODE project has produced a collection of Google Earth-based marine geology teaching resources that offer grand tours of the world's ocean basins and marine sediments. We use a map of oceanic crustal ages from Müller et al (2008; doi:10.1029/2007GC001743), and a set of emergent COLLADA models of IODP drill core data as a basis for a Google Earth tour introducing students to the world's ocean basins. Most students are familiar with basic seafloor spreading patterns but teaching experience suggests that few students have an appreciation of the number of abandoned ocean basins on Earth. Students also lack a valid visualization of the west Pacific where the oldest crust forms an isolated triangular patch and the ocean floor becomes younger towards the subduction zones. Our tour links geographic locations to mechanical models of rifting, seafloor spreading, subduction, and transform faulting. Google Earth's built-in earthquake and volcano data are related to ocean floor patterns. Marine sediments are explored in a Google Earth tour that draws on exemplary IODP core samples of a range of sediment types (e.g., turbidites, diatom ooze). Information and links are used to connect location to sediment type. This tour compliments a physical core kit of core catcher sections that can be employed for classroom instruction (geode.net/marine-core-kit/). At a larger scale, we use data from IMLGS to explore the distribution of the marine sediments types in the modern global ocean. More than 2,500 sites are plotted with access to original data. Students are guided to compare modern "type sections" of primary marine sediment lithologies, as well as examine site transects to address questions of bathymetric setting, ocean circulation, chemistry (e.g., CCD), and bioproductivity as influences on modern seafloor sedimentation. KMZ files, student exercises, and tips for instructors are available at geode.net/exploring-marine-sediments-using-google-earth.

  15. Contrasting sediment records of marine submersion events related to wave exposure, Southwest France

    Science.gov (United States)

    Baumann, J.; Chaumillon, E.; Schneider, J.-L.; Jorissen, F.; Sauriau, P.-G.; Richard, P.; Bonnin, J.; Schmidt, S.

    2017-05-01

    Sediment records of two contrasting backshore coastal marshes, extremely vulnerable to recent and historical marine flooding events, located on the SW coast of France, have been investigated using a multiproxy approach. The studied marshes are 30 km apart and have been flooded by similar storm events (7 marine floods in the last 250 years). One is located in a wave-exposed coast but isolated from the sea by a sediment barrier, whereas the other is located in a sheltered estuarine environment and isolated from the sea by a dike. One core was collected in each marsh and information on grain-size, foraminifera, shell contents and stable carbon isotopes was obtained along with an age model using 210Pb, 137Cs and 14C. Core data combined with historical maps give evidence of a typical estuarine backfilling, part of the Holocene regressive parasequence, including an intertidal mudflat at the base and a backshore environment at the top. Despite the absence of grain size anomalies, marine flood-related sedimentation in the backshore area of both marshes is identified by a mixture of marine and terrestrial features, including marine fauna, vegetation debris and variation in the δ13C signature of the organic fraction. Very low sedimentation rates between flood events and/or bioturbation prevents the identification of individual episodic marine floods in the sediment succession. Comparison of the two sedimentary successions shows that the foraminifera deposited by marine submersions are of two different types. Foraminifera are monospecific and originate from the upper tidal mudflat in the sheltered marsh; whereas in the backshore marsh located in a wave-exposed environment, they show higher diversity and originate from both shallow and deeper water marine environments. This study shows that wave exposure can control the faunal content of marine flood sediment records in coastal marshes.

  16. Effects of bioturbation on the fate of oil in coastal sandy sediments--an in situ experiment.

    Science.gov (United States)

    Timmermann, Karen; Banta, Gary T; Klinge, Lars; Andersen, Ole

    2011-03-01

    Effects of bioturbation by the common lugworm Arenicola marina on the fate of oil hydrocarbons (alkanes and PAHs) were studied in situ during a simulated oil spill in a shallow coastal area of Roskilde fjord, Denmark. The fate of selected oil compounds was monitored during 120 d using GC-MS and bioturbation activity (feces production and irrigation) was measured regularly during the experiment and used as input parameters in a mechanistic model describing the effects of A. marina on the transport and degradation of oil compounds in the sediment. The chemical analytical data and model results indicated that A. marina had profound and predictable effects on the distribution, degradation and preservation of oil and that the net effect depended on the initial distribution of oil. In sediment with an oil contaminated subsurface-layer A. marina buried the layer deeper in the sediment which clearly enhanced oil persistence. Conversely, A. marina stimulated both the physical removal and microbial degradation of oil compounds in uniformly oil contaminated sediments especially in deeper sediment layers (10-20 cm below the surface), whereas the fate of oil compounds deposited in surface layers (0-5 cm) mainly was affected by removal processes induced by wave actions and other bioturbating infauna such as Nereis diversicolor, Corophium volutator and Hydrobia spp. present in the experimental plots. Copyright © 2010 Elsevier Ltd. All rights reserved.

  17. 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.

  18. 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

  19. Combined effects of dam removal and past sediment mining on a relatively large lowland sandy gravel bed river (Vienne River, France)

    Science.gov (United States)

    Ursache, Ovidiu; Rodrigues, Stephane; Bouchard, Jean-Pierre; Jugé, Philippe; Richard, Nina

    2014-05-01

    Dam removal is of growing interest for the management of sediment fluxes within fluvial basins, morphological evolution and ecological restoration of rivers. If dam removal experiments are now quite well documented for small streams located in the upstream parts of river networks, examples of lowland and relatively large rivers are still scarce. In this study we present a dam removal operation carried out on the Vienne River (France) to restore both sediment and biotic continuity. The Vienne River is 363 km in length. On its middle reaches the average slope is equal to 0.0003 m.m-1 and the average annual discharge is 195 m3.s-1 at the gauging station of Nouâtre. The river is characterized by a sinuous single channel of an average width of 150 m. The sediments are mainly made of a siliceous mixture of sands and gravels and were intensively mined between years 1930 and 1995's. In 1920, a 4 m height dam was built just downstream the confluence between the Vienne and Creuse Rivers triggering a total sediment deposition upstream of 900 000 m3 in 75 years. Hence, in 1998, the removal of the dam increased severely the sediment supply delivered to the Vienne River. The objective of this study is to understand and quantify the fluvial processes and morphological evolution on a reach of 50 km of the Vienne associated with the dam remova and the presence of ancient sand pits located along the riverbed. This study is based on field data collected during 7 surveys performed between 1998 and 2013. This large dataset focuses on bed geometry (detailed bathymetrical surveys), sediment grain size, and bedload fluxes measured using isokinetic samplers. It was combined with a 1D numerical model developed to assess flow dynamics and sediment transport capacity before and after dam removal. Results show that dam removal triggered both headward and progressive (near the dam) erosions and that discharges higher than 100 m3.s-1 were sufficient to erode the sandy sediments trapped by the

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

    Science.gov (United States)

    Sakellariadou, F.

    2012-04-01

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

  1. Ecotoxicological evaluation of marine sediments using free and immobilized phytoplanktonic algae

    Directory of Open Access Journals (Sweden)

    E. Giacco

    2011-01-01

    Full Text Available Marine sediments play an important role in the accumulation-storage and/or release of contaminants in seawaters; sedimets bioassays provide for general information on pollutant bioavailability. This work points out the importance to utilize free and immobilised (Na-alginate marine algae for the ecotoxicological evaluation of metals (Cd, Zn, Cu as well as of elutriates and whole sediment samples collected in harbour sites. The bioassay was carried out with the marine microalga Tetraselmis suecica; algal growth inhibition was determined after 24 and 48 hours as percent growth in comparison to controls. After 24 hours a lower toxicity of metals for the immobilised algae than for free algae was observed; this trend decreased in time. Algae exposed to whole sediment ahowed a greater reduction of growth than algae exposed to the relative elutriate. This result emphasizes that the whole sediments seem to be suitable to detect the toxicity of such complex environmental matrix.

  2. 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

  3. Foraminiferal indicators of high OC content in marine sediments; a question of OC source?

    Science.gov (United States)

    Lo Giudice Cappelli, Elena; Austin, William; Smith, Laura; Ward, Hannah; Clarke, Jess; Green, Jade; Smeaton, Craig

    2017-04-01

    West Shetland voes (sea inlets), on Scotland northern maritime periphery, represent a range of environmental and depositional settings in an area of coastal ocean which is characterised by a generally high organic carbon content in marine sediments. Possible sources of organic carbon are fish farms, as this region is experiencing a large expansion in marine aquaculture, and/or erosion of peatland. Twenty-one sites in six voes were sampled in August 2015 following an organic carbon gradient. The aims of this study are: 1) to establish the modern biogeography of benthic foraminifera in west Shetland voes, 2) to explore the use of these organisms as bio-indicators of high organic carbon content in marine sediments, and 3) to trace the source of organic carbon and its transportation between different habitats and pools (e.g.: terrestrial to marine; marine aquaculture to sediments). To achieve this, we paired together spatial variations in the composition of benthic foraminiferal assemblages (species abundance and diversity) with changes in the physical properties of marine sediments determined by carbon stable isotope measurements and loss on ignition analysis. Preliminary results show a positive relationship between high abundance of the agglutinated benthic foraminifera Eggerelloides scaber, high organic carbon content in the sediments and proximity to fish farms. Although aquaculture farming in these areas may be a contributing factor, radiocarbon dates demonstrate that organic enrichment in the sediments pre-dates the introduction of aquaculture, while carbon stable isotope measurements point to peat erosion as a more likely source of organic carbon in west Shetland voes. Therefore, peatland erosion is a significant source of organic carbon in marine sediments and may be an important contributor to the store of blue carbon in west Shetland voes and, more in general, in the coastal ocean.

  4. Effect of soil crusting on the emission and transport of wind-eroded sediment: field measurements on loamy sandy soil

    NARCIS (Netherlands)

    Goossens, D.

    2004-01-01

    Abstract Field data are reported for the horizontal and vertical flux of wind-eroded sediment on an agricultural field in northern Germany. Measurements were made during a windstorm that hit the region on 18 May 1999. The magnitude of both fluxes was significantly affected by the presence of a

  5. 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

    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......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...... 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...

  6. 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.

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

    Science.gov (United States)

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

    1989-01-01

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

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

    National Research Council Canada - National Science Library

    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...

  9. Effect of 2,4-dinitrotoluene on the anaerobic bacterial community in marine sediment.

    Science.gov (United States)

    Yang, H; Zhao, J-S; Hawari, J

    2009-12-01

    To study the impact of added 2,4-dinitrotoluene (DNT) on the anaerobic bacterial community in marine sediment collected from an unexploded ordnance dumping site in Halifax Harbour. Marine sediment was spiked with 2,4-DNT and incubated under anaerobic conditions in the presence and absence of lactate. Indigenous bacteria in the sediment removed 2,4-DNT with subsequent formation of its mono- and diamino-derivatives under both conditions. PCR-DGGE and nucleotide sequencing were used to monitor the change in the bacterial population in sediment caused by the presence of 2,4-DNT. The results showed that denaturing gradient gel electrophoresis banding patterns of sediment microcosms treated with 2,4-DNT were different from controls that did not receive 2,4-DNT. Bacteroidetes, Firmicutes and delta-Proteobacteria were present in sediment incubated in the absence of 2,4-DNT. However, several gamma-Proteobacteria became dominant in sediment in the presence of 2,4-DNT, two of which were 99% similar to Shewanella canadensis and Shewanella sediminis. In the presence of both 2,4-DNT and lactate, two additional delta-Proteobacteria were enriched, one closely related (98% similarity) to Desulfofrigus fragile and the other affiliated (96% similarity) to Desulfovibrio sp. In contrast, none of the above four Proteobacteria were enriched in sediment incubated with lactate alone. Presence of 2,4-DNT led to a significant change in bacterial population of marine sediment with the enrichment of several gamma- and delta-Proteobacteria. Our results provided the first evidence on the impact of the pollutant 2,4-DNT on the indigenous bacterial community in marine sediment, and provided an insight into the composition of bacterial community that degrade 2,4-DNT.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-12-31

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

  11. 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.

  12. Ocean currents shape the microbiome of Arctic marine sediments

    National Research Council Canada - National Science Library

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

    2013-01-01

    ...). Water and sediment directly underlying water with origin in the Arctic, Pacific or Atlantic oceans were analyzed by pyrosequencing and length heterogeneity-PCR in conjunction with physicochemical...

  13. Maps showing bathymetry and modern sediment thickness on the inner continental shelf offshore of Fire Island, New York, pre-Hurricane Sandy

    Science.gov (United States)

    Schwab, William C.; Denny, Jane F.; Baldwin, Wayne E.

    2014-01-01

    The U.S. Geological Survey mapped approximately 336 square kilometers of the lower shoreface and inner continental shelf offshore of Fire Island, New York, in 2011 by using interferometric sonar and high-resolution chirp seismic-reflection systems. This report presents maps of bathymetry, acoustic backscatter, the coastal plain unconformity, the Holocene marine transgressive surface, and modern sediment thickness. These spatial data support research on the Quaternary evolution of the Fire Island coastal system and provide baseline information for research on coastal processes along southern Long Island.

  14. Marinobacter sp. from marine sediments produce highly stable surface-active agents for combatting marine oil spills.

    Science.gov (United States)

    Raddadi, Noura; Giacomucci, Lucia; Totaro, Grazia; Fava, Fabio

    2017-11-02

    The application of chemical dispersants as a response to marine oil spills is raising concerns related to their potential toxicity also towards microbes involved in oil biodegradation. Hence, oil spills occurring under marine environments necessitate the application of biodispersants that are highly active, stable and effective under marine environment context. Biosurfactants from marine bacteria could be good candidates for the development of biodispersant formulations effective in marine environment. This study aimed at establishing a collection of marine bacteria able to produce surface-active compounds and evaluating the activity and stability of the produced compounds under conditions mimicking those found under marine environment context. A total of 43 different isolates were obtained from harbor sediments. Twenty-six of them produced mainly bioemulsifiers when glucose was used as carbon source and 16 were biosurfactant/bioemulsifiers producers after growth in the presence of soybean oil. Sequencing of 16S rRNA gene classified most isolates into the genus Marinobacter. The produced emulsions were shown to be stable up to 30 months monitoring period, in the presence of 300 g/l NaCl, at 4 °C and after high temperature treatment (120 °C for 20 min). The partially purified compounds obtained after growth on soybean oil-based media exhibited low toxicity towards V. fischeri and high capability to disperse crude oil on synthetic marine water. To the best of our knowledge, stability characterization of bioemulsifiers/biosurfactants from the non-pathogenic marine bacterium Marinobacter has not been previously reported. The produced compounds were shown to have potential for different applications including the environmental sector. Indeed, their high stability in the presence of high salt concentration and low temperature, conditions characterizing the marine environment, the capability to disperse crude oil and the low ecotoxicity makes them interesting for

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-03-25

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

  16. In Situ Stabilization of Persistent Organic Contaminants in Marine Sediments

    Science.gov (United States)

    2004-04-01

    particles (primarily coal, coke, charcoal, pitch, cenospheres , and wood). The carbonaceous sediment fractions were separated from the mineral fractions...sorbed on carbonaceous particles such as coal, coke, charcoal, and cenosphere . Results of this study illustrate the importance of understanding...and carbonaceous particles (primarily coal, coke, charcoal, pitch, cenospheres , and wood). The carbonaceous sediment fractions were separated from the

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

    Digital Repository Service at National Institute of Oceanography (India)

    Sarkar, A.

    The inhibitory effects of the organics from the sediment along the east coast of India on acetylcholinesterase (AChE) in-vitro were evaluated. Sediment samples collected from the surface layers at various depths were extracted. Each of the extracts...

  18. 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 combined...

  19. Volatile fatty acid cycling in organic-rich marine sediments

    Science.gov (United States)

    Sansone, Francis J.; Martens, Christopher S.

    1982-09-01

    Volatile fatty acid (VFA) apparent turnover rates were determined by measuring whole sediment VFA concentrations and the corresponding reaction rate constants. The following ranges of VFA concentrations were measured in Cape Lookout Bight, N.C. sediments (μmole·l s-1): acetate 54-660, propionate 1-24, butyrate iso-butyrate <0.5-6. Apparent turnover rates measured over a one-year period ranged from 18-600 μmole·l s-1·h -1 for acetate and 0.7-7 μmole·l s-1·h -1 for the carboxyl carbon of propionate. Methane production was observed only with acetate and only in sulfatedepleted sediments; total acetate turnover attained approximately the same maximum value in both sulfate-reducing and sulfate-depleted sediments. Apparent turnover rates for acetate and propionate appeared to be controlled by similar factors: in sulfate-reducing (surface) sediments the turnover rates were stimulated by autumn storm-mediated deposition/resuspension events; in deeper sulfate-depleted sediments the turnover rates followed changes in the ambient temperature. Changes in VFA poolsizes were proportionally much larger than changes in corresponding rate constants. The ratio of CO 2 to CH 4 produced from acetate vs. depth suggested that non-methanogenic bacteria accounted for 60% of the acetate turnover in sulfate-depleted sediments. VFA concentrations were much lower in N.C. continental slope mud than in Cape Lookout sediments; acetate was the only VFA detectable throughout the top 40 cm of the slope sediments. The estimated production rate of CO 2 from acetate decreased rapidly with depth. The surface rate was approximately 20 times less than that measured at similar temperatures in sulfate-reducing Cape Lookout sediments.

  20. Estimating Production and Consumption of Solid Reactive Fe Phases in Marine Sediments from Concentration Profiles

    Science.gov (United States)

    Devereux, R.; Lettmann, K.; Lehrter, J. C.; Beddick, D. L., Jr.; Yates, D. F.; Hoglund, M.; Rogers, J. E.; Jarvis, B.

    2016-02-01

    1D diffusion models may be used to estimate rates of production and consumption of dissolved metabolites in marine sediments but are applied less often to the solid phase. Here we used a numerical inverse method assuming steady state conditions to estimate solid phase Fe(III) and Fe(II) consumption and production rates, respectively, from sediment concentration profiles. First, porewater concentration profiles of dissolved inorganic carbon (DIC) and ammonium (NH4+) in muddy northern Gulf of Mexico sediments were analyzed by the model. The runs were used to fit model concentration outputs to sediment sample data, identify zones of production and consumption, and obtain modeled fluxes across the sediment-water interface that best matched experimentally-obtained flux rates. Modeled fluxes were sensitive to coefficients of sediment irrigation and bioturbation in addition to boundary concentrations. Assuming diffusion coefficients = 0 for solid phase minerals, drivers for estimating production and consumption rates from solid phase concentrations are then the rates of sedimentation and porewater advection, and coefficients of bioturbation and irrigation. Thus, applying the model with sediment irrigation and bioturbation terms obtained in the DIC and NH4+ runs, and replacing values of porosity with 1-porosity, rates of Fe(II) production closely matched rates of Fe(III) consumption at about 10-3 nmole cm-1 sec-1. High modeled Fe transformations occurred in the upper 3.5 cm of sediment. In addition, porewater Fe2+ and dissolved Mn concentration profiles both yielded modeled production in the top 0.5 cm of sediment with consumption below that suggesting a zone of precipitation as sulfide or carbonate minerals. These results demonstrate that simple 1D models can be applied to the solid phase of marine sediments and may additionally be helpful in estimating coefficients of sediment irrigation and bioturbation.

  1. 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.

  2. 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.

  3. Estimates of biogenic methane production rates in deep marine sediments at Hydrate Ridge, Cascadia margin.

    Science.gov (United States)

    Colwell, F S; Boyd, S; Delwiche, M E; Reed, D W; Phelps, T J; Newby, D T

    2008-06-01

    Methane hydrate found in marine sediments is thought to contain gigaton quantities of methane and is considered an important potential fuel source and climate-forcing agent. Much of the methane in hydrates is biogenic, so models that predict the presence and distribution of hydrates require accurate rates of in situ methanogenesis. We estimated the in situ methanogenesis rates in Hydrate Ridge (HR) sediments by coupling experimentally derived minimal rates of methanogenesis to methanogen biomass determinations for discrete locations in the sediment column. When starved in a biomass recycle reactor, Methanoculleus submarinus produced ca. 0.017 fmol methane/cell/day. Quantitative PCR (QPCR) directed at the methyl coenzyme M reductase subunit A gene (mcrA) indicated that 75% of the HR sediments analyzed contained methane produced/g sediment/day for the samples with fewer methanogens than the QPCR method could detect. The actual rates could vary depending on the real number of methanogens and various seafloor parameters that influence microbial activity. However, our calculated rate is lower than rates previously reported for such sediments and close to the rate derived using geochemical modeling of the sediments. These data will help to improve models that predict microbial gas generation in marine sediments and determine the potential influence of this source of methane on the global carbon cycle.

  4. The life sulfuric: microbial ecology of sulfur cycling in marine sediments

    Science.gov (United States)

    Wasmund, Kenneth; Mußmann, Marc

    2017-01-01

    Summary Almost the entire seafloor is covered with sediments that can be more than 10 000 m thick and represent a vast microbial ecosystem that is a major component of Earth's element and energy cycles. Notably, a significant proportion of microbial life in marine sediments can exploit energy conserved during transformations of sulfur compounds among different redox states. Sulfur cycling, which is primarily driven by sulfate reduction, is tightly interwoven with other important element cycles (carbon, nitrogen, iron, manganese) and therefore has profound implications for both cellular‐ and ecosystem‐level processes. Sulfur‐transforming microorganisms have evolved diverse genetic, metabolic, and in some cases, peculiar phenotypic features to fill an array of ecological niches in marine sediments. Here, we review recent and selected findings on the microbial guilds that are involved in the transformation of different sulfur compounds in marine sediments and emphasise how these are interlinked and have a major influence on ecology and biogeochemistry in the seafloor. Extraordinary discoveries have increased our knowledge on microbial sulfur cycling, mainly in sulfate‐rich surface sediments, yet many questions remain regarding how sulfur redox processes may sustain the deep‐subsurface biosphere and the impact of organic sulfur compounds on the marine sulfur cycle. PMID:28419734

  5. Sediment community responses to marine vs. terrigenous organic matter in a submarine canyon

    OpenAIRE

    Hunter, W. R.; Jamieson, A; Huvenne, V. A. I.; Witte, U

    2013-01-01

    The Whittard Canyon is a branching submarine canyon on the Celtic continental margin, which may act as a conduit for sediment and organic matter (OM) transport from the European continental slope to the abyssal sea floor. In situ stable-isotope labelling experiments were conducted in the eastern and western branches of the Whittard Canyon, testing short-term (3–7 days) responses of sediment communities to deposition of nitrogen-rich marine (Thalassiosira weissflogii) and ni...

  6. Estimation of carbonate concentration and characterization of marine sediments by Fourier transform infrared spectroscopy.

    Digital Repository Service at National Institute of Oceanography (India)

    Veerasingam, S.; Venkatachalapathy, R.

    of CaCO3 is usually attributed to the shells of marine planktonic organisms, specially coccolithophores, foraminifera and pteropods. Biogenic carbonates are formed in surface waters and within surficial sediments, and eventually accumulate... such as ocean acidification on ecosystems. Thus, a rapid, cheap and non-destructive tool is required to investigate the distribution of CaCO3 in sediments for the understanding of the fate of biologically produced carbonate. 3    FTIR spectroscopy is one...

  7. Deep-Water Ambient Noise Profiling; Marine Sediment Acoustics; and Doppler Geo-Acoustic Spectroscopy

    Science.gov (United States)

    2013-09-30

    Acoustics; and Doppler Geo-Acoustic Spectroscopy Michael J. Buckingham Marine Physical Laboratory, Scripps Institution of Oceanography University...second-order spatial statistics of the noise. 2) Marine sediment acoustics Develop a unified, physics -based model of sound wave and shear wave...T. K. Berger and M. J. Buckingham, “Sensitivity of an underwater acoustic array to ultra-high energy neutrinos,” Astroparticle Phys., 697, 1-14

  8. 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....

  9. Reductive Dechlorination of Polychlorinated Biphenyls in Marine Sediments

    National Research Council Canada - National Science Library

    Sowers, Kevin

    1999-01-01

    ... Community by Comparative Sequence Analysis of Genes Coding for 16S rRNA, Microbial Reductive Dechlorination of Aroclor 1260 in Anaerobic Slurries of Estuarine Sediments, Differential RFLP patterns of PCR...

  10. Diversity of cultivable actinobacteria in geographically widespread marine sediments.

    Science.gov (United States)

    Maldonado, Luis A; Stach, James E M; Pathom-aree, Wasu; Ward, Alan C; Bull, Alan T; Goodfellow, Michael

    2005-01-01

    Reports describing actinobacteria isolated from marine environments have been dominated by Micromonospora, Rhodococcus and Streptomyces species. Recent culture-independent studies have shown that marine environments contain a high diversity of actinobacterial species that are rarely, if at all, recovered by cultivation-based methods. In this study, it is shown that cultivation-independent methods can be used to guide the application of selective isolation methods. The detection of marine-derived actinobacterial species that have previously only been reported from terrestrial habitats is highlighted. This study provides good evidence that the previously described low diversity of actinobacterial species isolated from marine environments does not reflect an actual low species diversity, and that the use of informed selective isolation procedures can aid in the isolation of members of novel taxa.

  11. Sensitivity of the marine benthic copepod Tisbe biminiensis (copepoda, harpacticoida) to potassium dichromate and sediment particle size

    OpenAIRE

    Cristiane M. V. Araújo-Castro; Souza-Santos, Lília P.; Torreiro,Anny Gabrielle A .G.; Garcia, Karina S.

    2009-01-01

    For the future use of the marine benthic copepod Tisbe biminiensis in solid-phase sediment toxicological bioassays, the present study investigated the effect of muddy sediment from the Maracaípe estuary (northeastern Brazil), sediment particle size and the reference toxicant potassium dichromate on the species. Muddy sediment from Maracaípe can be used as control sediment, since it does not interfere in the copepod life-cycle and has metal contamination levels that are unlikely to produce any...

  12. Geochemical Tools and Paleoclimate Clues: Multi-Molecular and Isotopic Investigations of Tropical Marine Sediments and Alpine Ice

    Science.gov (United States)

    2006-02-01

    B. (1987) Marine and terrigenous lipids in coastal sediments from the Peru upwelling region at 15’S: Sterols and triterpene alcohols. Organic...B. (1987) Marine and terrigenous lipids in coastal sediments from the Peru upwelling region at 15’S: Sterols and triterpene alcohols. Organic

  13. Sand on the move: Post Hurricane Sandy analysis of the coastal sediment budget and bedform migration at Jones Inlet, Long Island, NY

    Science.gov (United States)

    Bales, M. K.; Goff, J. A.; Austin, J. A.; Flood, R. D.; Christensen, B. A.; Browne, C. M.; Saustrup, S.

    2013-12-01

    Hurricane Sandy struck the Northeast coast of the United States on October 29, 2012. Although sustained winds were downgraded to ~70 kts upon landfall, the vast area of the storm along with the direction of impact resulted in major storm-surge flooding and damage, as well as significant changes to the morphology of the coast-line, altering the characteristics of major barrier islands, inlets, and estuaries. A January 2013 post-storm survey aboard the R/V Pritchard, conducted by the University of Texas Institute for Geophysics, Stony Brook University, and Adelphi University, sought to investigate the impact of this post-tropical cyclone on the southwestern coast of Long Island, NY which sustained storm surges of up to 4 m above normal sea level. The objective of this project is to gain insight on the sedimentological volume changes and bathymetrical alterations made on the seafloor within Jones Inlet and the immediate estuaries behind Jones Beach and Long Beach Island. By studying these changes we hope to gain a better understanding of how large cyclonic storms alter sediment volumes and seafloor topography within major inlets and estuarine systems. These modifications can be observed in post-storm multibeam swath bathymetry and backscatter when compared to similar pre-storm data collected in 2010 by Stony Brook University. Post-storm CHIRP seismic reflection data were also collected, in order to define stratigraphic geometries, as well as grab samples to determine grain size distributions and ground truth for the backscatter data. The acoustic reflections imaged in the CHIRP data allow basal reflectors and dominate horizons to be traced throughout the inlet and estuaries. Our analysis focuses on (1) defining and quantifying areas of deposition and erosion from before-and-after bathymetry data; (2) comparing bedform patterns and grain size distributions from before-and-after backscatter and grab sample analysis; and (3) defining stratal geometries of the shallow

  14. Statistical approaches for estimating actinobacterial diversity in marine sediments.

    Science.gov (United States)

    Stach, James E M; Maldonado, Luis A; Masson, Douglas G; Ward, Alan C; Goodfellow, Michael; Bull, Alan T

    2003-10-01

    Bacterial diversity in a deep-sea sediment was investigated by constructing actinobacterium-specific 16S ribosomal DNA (rDNA) clone libraries from sediment sections taken 5 to 12, 15 to 18, and 43 to 46 cm below the sea floor at a depth of 3,814 m. Clones were placed into operational taxonomic unit (OTU) groups with >/= 99% 16S rDNA sequence similarity; the cutoff value for an OTU was derived by comparing 16S rRNA homology with DNA-DNA reassociation values for members of the class Actinobacteria. Diversity statistics were used to determine how the level of dominance, species richness, and genetic diversity varied with sediment depth. The reciprocal of Simpson's index (1/D) indicated that the pattern of diversity shifted toward dominance from uniformity with increasing sediment depth. Nonparametric estimation of the species richness in the 5- to 12-, 15- to 18-, and 43- to 46-cm sediment sections revealed a trend of decreasing species number with depth, 1,406, 308, and 212 OTUs, respectively. Application of the LIBSHUFF program indicated that the 5- to 12-cm clone library was composed of OTUs significantly (P = 0.001) different from those of the 15- to 18- and 43- to 46-cm libraries. F(ST) and phylogenetic grouping of taxa (P tests) were both significant (P diversity decreased with sediment depth and that each sediment community harbored unique phylogenetic lineages. It was also shown that even nonconservative OTU definitions result in severe underestimation of species richness; unique phylogenetic clades detected in one OTU group suggest that OTUs do not correspond to real ecological groups sensu Palys (T. Palys, L. K. Nakamura, and F. M. Cohan, Int. J. Syst. Bacteriol. 47:1145-1156, 1997). Mechanisms responsible for diversity and their implications are discussed.

  15. A small-scale, portable method for extracting microplastics from marine sediments.

    Science.gov (United States)

    Coppock, Rachel L; Cole, Matthew; Lindeque, Penelope K; Queirós, Ana M; Galloway, Tamara S

    2017-11-01

    Microplastics (plastic particles, 0.1 μm-5 mm in size) are widespread marine pollutants, accumulating in benthic sediments and shorelines the world over. To gain a clearer understanding of microplastic availability to marine life, and the risks they pose to the health of benthic communities, ecological processes and food security, it is important to obtain accurate measures of microplastic abundance in marine sediments. To date, methods for extracting microplastics from marine sediments have been disadvantaged by complexity, expense, low extraction efficiencies and incompatibility with very fine sediments. Here we present a new, portable method to separate microplastics from sediments of differing types, using the principle of density floatation. The Sediment-Microplastic Isolation (SMI) unit is a custom-built apparatus which consistently extracted microplastics from sediments in a single step, with a mean efficiency of 95.8% (±SE 1.6%; min 70%, max 100%). Zinc chloride, at a density of 1.5 g cm -3 , was deemed an effective and relatively inexpensive floatation media, allowing fine sediment to settle whilst simultaneously enabling floatation of dense polymers. The method was validated by artificially spiking sediment with low and high density microplastics, and its environmental relevance was further tested by extracting plastics present in natural sediment samples from sites ranging in sediment type; fine silt/clay (mean size 10.25 ± SD 3.02 μm) to coarse sand (mean size 149.3 ± SD 49.9 μm). The method presented here is cheap, reproducible and is easily portable, lending itself for use in the laboratory and in the field, eg. on board research vessels. By employing this method, accurate estimates of microplastic type, distribution and abundance in natural sediments can be achieved, with the potential to further our understanding of the availability of microplastics to benthic organisms. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All

  16. Survival in seawater of Escherichia coli cells grown in marine sediments containing glycine betaine.

    OpenAIRE

    Gauthier, M J; Le Rudulier, D

    1990-01-01

    Considering both the protective effect of glycine betaine (GB) on enteric bacteria grown at high osmolarity and the possible presence of GB in marine sediments, we have analyzed the survival, in nutrient-free seawater, of Escherichia coli cells incubated in sediments supplemented with GB or not supplemented and measured the efficiency of GB uptake systems and the expression of proP and proU genes in both seawater and sediments. We did this by using strains harboring proP-lacZ and proU-lacZ op...

  17. Isolation of broad-host-range replicons from marine sediment bacteria.

    Science.gov (United States)

    Sobecky, P A; Mincer, T J; Chang, M C; Toukdarian, A; Helinski, D R

    1998-08-01

    Naturally occurring plasmids isolated from heterotrophic bacterial isolates originating from coastal California marine sediments were characterized by analyzing their incompatibility and replication properties. Previously, we reported on the lack of DNA homology between plasmids from the culturable bacterial population of marine sediments and the replicon probes specific for a number of well-characterized incompatibility and replication groups (P. A. Sobecky, T. J. Mincer, M. C. Chang, and D. R. Helinski, Appl. Environ. Microbiol. 63:888-895, 1997). In the present study we isolated 1.8- to 2.3-kb fragments that contain functional replication origins from one relatively large (30-kb) and three small (marine isolates. 16S rRNA sequence analyses indicated that the four plasmid-bearing marine isolates belonged to the alpha and gamma subclasses of the class Proteobacteria. Three of the marine sediment isolates are related to the gamma-3 subclass organisms Vibrio splendidus and Vibrio fischeri, while the fourth isolate may be related to Roseobacter litoralis. Sequence analysis of the plasmid replication regions revealed the presence of features common to replication origins of well-characterized plasmids from clinical bacterial isolates, suggesting that there may be similar mechanisms for plasmid replication initiation in the indigenous plasmids of gram-negative marine sediment bacteria. In addition to replication in Escherichia coli DH5alpha and C2110, the host ranges of the plasmid replicons, designated repSD41, repSD121, repSD164, and repSD172, extended to marine species belonging to the genera Achromobacter, Pseudomonas, Serratia, and Vibrio. While sequence analysis of repSD41 and repSD121 revealed considerable stretches of homology between the two fragments, these regions do not display incompatibility properties against each other. The replication origin repSD41 was detected in 5% of the culturable plasmid-bearing marine sediment bacterial isolates, whereas the

  18. 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.

  19. Isotopic compositions of tropical East African flora and their potential as source indicators of organic matter in coastal marine sediments

    Science.gov (United States)

    Muzuka, Alfred N. N.

    1999-04-01

    The C and N stable isotope compositions of some flora of East Africa from coastal Tanzania and Amboseli National Park (Kenya) are used to assess if they can be used as a terrestrial end member during the estimation of terrestrial fraction in coastal marine sediments. The results of C isotope composition of various tree leaves, which average -29.3 ± 1.4%, indicate that these tropical higher land plant species follow a Calvin-Benson or non-Kranz (C 3) type of metabolism. The results for grass species, which average -13.2 ± 2.4%, indicate that most of them follow a Hatch-Slack or Kranz (C 4) type of metabolism. However, some of the succulent plants from the Amboseli National Park have δ13C values that average -14.7%, an indication that they follow a CAM (Crassulacean Acid Metabolism) type of metabolism. The N isotope values are relatively higher than expected for the terrestrial organic material. The average δ15N values for both tree and grass samples are higher than 5% and fall within the range normally considered to be marine. The high enrichment in 15N may be related to the environmental conditions in which plants thrive. Plants growing in sandy, dry and overgrazed environments are expected to be enriched in 15N owing to full utilisation of all available N species, regardless of their isotopic compositions. Other processes which may cause an enrichment in 15N include adsorption by various types of clay minerals, supply of 15N-enriched nitrate through sea-spray, and local denitrification, especially in swampy and lake margins where the input of organic matter may be higher than the rate of decomposition. The stable isotopic composition of organic C and N for surficial organic matter for the coastal marine sediments averages -17.0 ± 0.9% and 5.4 ± 1.1%, respectively. These values indicate a substantial contribution of C 4 plants and sea grasses. However, contribution of C 4 relative to that of sea grasses can not be evaluated owing to the fact that there is no

  20. Abiotic racemization kinetics of amino acids in marine sediments

    DEFF Research Database (Denmark)

    Steen, Andrew; Jørgensen, Bo Barker; Lomstein, Bente Aagaard

    2013-01-01

    Enantiomeric ratios of amino acids can be used to infer the sources and composition of sedimentary organic matter. Such inferences, however, rely on knowing the rates at which amino acids in sedimentary organic racemize abiotically. Based on a heating experiment, we report Arrhenius parameters...... for aspartic acid, glutamic acid, serine, and alanine in bulk sediment from Aarhus Bay, Denmark, taken from the surface, 30 cm, and 340 cm depth. Extrapolation to a typical cold deep sea sediment temperature of 3 °C suggests racemization rate constants of on the order of 10-5 yr-1 without evident differences...... between different amino acids or depths. These results can be used in conjunction with measurements of sediment age to predict the ratio of D:L amino acids due solely to abiotic racemization of the source material, deviations from which can indicate the abundance and turnover of active microbial...

  1. 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.......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....

  2. 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...

  3. A new variety of Chainia olivacea from marine sediment off Gulf of Mannar.

    Science.gov (United States)

    Ellaiah, P; Kalyan, D; Rao, V S; Rao, B V

    1997-01-01

    A new variety of Chainia olivacea was isolated from marine sediment off Gulf of Mannar. The morphological, cultural, physiological and biochemical characters were studied, compared to known species and identified as a new variety of Chainia olivacea. Antibiotic activity of the strain was tested against both Gram positive and Gram negative bacteria as well as fungi and yeasts. Sodium chloride tolerance was also tested.

  4. Quantifying the degradation of organic matter in marine sediments: A review and synthesis

    NARCIS (Netherlands)

    Arndt, S.; Jørgensen, B.B.; LaRowe, D.E.; Middelburg, J.J.; Pancost, R.D.; Regnier, P.

    2013-01-01

    Quantifying the rates of biogeochemical processes in marine sediments is essential for understanding global element cycles and climate change. Because organic matter degradation is the engine behind benthic dynamics, deciphering the impact that various forces have on this process is central to

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

    Science.gov (United States)

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

    2013-06-01

    Sediment samples collected off the coast of San Diego were analyzed for actinomycete diversity using culture-independent techniques. Eight new operational taxonomic units (OTUs) in the Streptomycetaceae were identified as well as new diversity within previously cultured marine OTUs. Sequences belonging to the marine actinomycete genus Salinispora were also detected, despite the fact that this genus has only been reported from more tropical environments. Independent analyses of marine sediments from the Canary Basin (3814 m) and the South Pacific Gyre (5126 and 5699 m) also revealed Salinispora sequences providing further support for the occurrence of this genus in deep-sea sediments. Efforts to culture Salinispora spp. from these samples have yet to be successful. This is the first report of Salinispora spp. from marine sediments > 1100 m and suggests that the distribution of this genus is broader than previously believed. © 2013 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  6. Anaerobic oxidation of methane and its impact on iron and phosphorus cycling in marine sediments

    NARCIS (Netherlands)

    Egger, M.J.|info:eu-repo/dai/nl/372629199

    2016-01-01

    Methane (CH4) represents one of the key compounds in the global carbon (C) cycle. A major proportion of the CH4 in the Earth system is produced in marine sediments by methanogenesis, the final step in the gradual fermentation of organic matter deposited on the seafloor. Once emitted to the

  7. Phylogenetic diversity of gram-positive bacteria cultured from marine sediments.

    Science.gov (United States)

    Gontang, Erin A; Fenical, William; Jensen, Paul R

    2007-05-01

    Major advances in our understanding of marine bacterial diversity have been gained through studies of bacterioplankton, the vast majority of which appear to be gram negative. Less effort has been devoted to studies of bacteria inhabiting marine sediments, yet there is evidence to suggest that gram-positive bacteria comprise a relatively large proportion of these communities. To further expand our understanding of the aerobic gram-positive bacteria present in tropical marine sediments, a culture-dependent approach was applied to sediments collected in the Republic of Palau from the intertidal zone to depths of 500 m. This investigation resulted in the isolation of 1,624 diverse gram-positive bacteria spanning 22 families, including many that appear to represent new taxa. Phylogenetic analysis of 189 representative isolates, based on 16S rRNA gene sequence data, indicated that 124 (65.6%) belonged to the class Actinobacteria while the remaining 65 (34.4%) were members of the class Bacilli. Using a sequence identity value of >/=98%, the 189 isolates grouped into 78 operational taxonomic units, of which 29 (37.2%) are likely to represent new taxa. The high degree of phylogenetic novelty observed during this study highlights the fact that a great deal remains to be learned about the diversity of gram-positive bacteria in marine sediments.

  8. Habitat-Specific Effects of Fishing Disturbance on Benthic Species Richness in Marine Soft Sediments

    NARCIS (Netherlands)

    van Denderen, D.; Hintzen, N.T.; Rijnsdorp, A.D.; Ruardij, P.; van Kooten, T.

    2014-01-01

    Around the globe, marine soft sediments on continental shelves are affected by bottom trawl fisheries. In this study, we explore the effect of this widespread anthropogenic disturbance on the species richness of a benthic ecosystem, along a gradient of bottom trawling intensities. We use data from

  9. Late Quaternary palynology in marine sediments: a synthesis of the understanding of pollen distribution patterns in the NW African setting.

    NARCIS (Netherlands)

    Hooghiemstra, H.; Lézine, A.M.; Leroy, S.A.G.; Dupont, L.; Marret, F.

    2006-01-01

    Abstract After a review of the first steps in marine palynology, we show that the understanding of the northwest African setting is crucial to evaluate the potential of marine palynological studies elsewhere. We studied distribution patterns of pollen grains in recent marine sediments off NW Africa

  10. The Global Inventory of Methane Hydrate in Marine Sediments: A Theoretical Approach

    Directory of Open Access Journals (Sweden)

    Andrew Dale

    2012-07-01

    Full Text Available The accumulation of methane hydrate in marine sediments is controlled by a number of physical and biogeochemical parameters including the thickness of the gas hydrate stability zone (GHSZ, the solubility of methane in pore fluids, the accumulation of particulate organic carbon at the seafloor, the kinetics of microbial organic matter degradation and methane generation in marine sediments, sediment compaction and the ascent of deep-seated pore fluids and methane gas into the GHSZ. Our present knowledge on these controlling factors is discussed and new estimates of global sediment and methane fluxes are provided applying a transport-reaction model at global scale. The modeling and the data evaluation yield improved and better constrained estimates of the global pore volume within the modern GHSZ ( ≥ 44 × 1015 m3, the Holocene POC accumulation rate at the seabed (~1.4 × 1014 g yr−1, the global rate of microbial methane production in the deep biosphere (4−25 × 1012 g C yr−1 and the inventory of methane hydrates in marine sediments ( ≥ 455 Gt of methane-bound carbon.

  11. Remediation of coastal marine sediments using granulated coal ash.

    Science.gov (United States)

    Asaoka, Satoshi; Yamamoto, Tamiji; Yoshioka, Ichiro; Tanaka, Hitoshi

    2009-12-15

    It is very important to reduce phosphorus flux from sediment as well as cutting down terrigenous loads in order to control eutrophication in semi-enclosed coastal seas. Hydrogen sulfide is also a noxious substance which is highly toxic and fatal to benthic organisms. The purpose of this study is to evaluate remediation efficiency of organically enriched sediments using granulated coal ash (GCA) in terms of reducing benthic phosphorus flux and hydrogen sulfide. A flow-through experimental system was used to simulate the semi-enclosed water bodies. The application of GCA decreased the concentration of PO4(3-) in the pore water effectively, and reduced phosphate releasing flux from the sediment into overlying water by 37-44% compared to the control. The hydrogen sulfide in the pore water was also decreased by 77-100%, due to adsorption onto the GCA and deactivation of sulfate-reducing bacteria due to increasing pH. Thus, GCA is a promising recycled material for reducing phosphate releasing flux from organically enriched sediment to alleviate eutrophication as well as reduce the concentration of hydrogen sulfide in pore water.

  12. Remediation of coastal marine sediments using granulated coal ash

    Energy Technology Data Exchange (ETDEWEB)

    Asaoka, S.; Yamamoto, T.; Yoshioka, I.; Tanaka, H. [Hiroshima University, Higashihiroshima (Japan)

    2009-12-15

    It is very important to reduce phosphorus flux from sediment as well as cutting down terrigenous loads in order to control eutrophication in semi-enclosed coastal seas. Hydrogen sulfide is also a noxious substance which is highly toxic and fatal to benthic organisms. The purpose of this study is to evaluate remediation efficiency of organically enriched sediments using granulated coal ash (GCA) in terms of reducing benthic phosphorus flux and hydrogen sulfide. A flow-through experimental system was used to simulate the semi-enclosed water bodies. The application of GCA decreased the concentration of PO{sub 4}{sup 3-} in the pore water effectively, and reduced phosphate releasing flux from the sediment into overlying water by 37-44% compared to the control. The hydrogen sulfide in the pore water was also decreased by 77-100%, due to adsorption onto the GCA and deactivation of sulfate-reducing bacteria due to increasing pH. Thus, GCA is a promising recycled material for reducing phosphate releasing flux from organically enriched sediment to alleviate eutrophication as well as reduce the concentration of hydrogen sulfide in pore water.

  13. Mineralogical and geochemical aspects of the marine sediments off Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Paropkari, A.L.

    environment caused by impingement of 'oxygen minimum' waters on the floor of the slope between water depths of 120 to 1200m. Phosphate concentrations in sediments are as such not very appreciable; its occurrence as concretions in the core collected from...

  14. Protozoan grazing increases mineralization of naphthalene in marine sediment.

    Science.gov (United States)

    Tso, Suk-Fong; Taghon, Gary L

    2006-05-01

    Bacterial decomposition of organic matter is frequently enhanced when protozoa are present. Various mechanisms have been proposed to account for this phenomenon, including effects associated with grazing by protozoa (such as increased recycling of limiting nutrients, removal of senescent cells, or reduction of competition among bacteria) and indirect effects of grazers (such as excretion of bacterial growth factors). Few studies have examined the role of protozoa in bacterial degradation of xenobiotic compounds in sediment containing a natural community of microbes. The effect of protozoa on mineralization of naphthalene was investigated in this study. Laboratory experiments were conducted using field-contaminated estuarine sediment, with the indigenous microbial populations. Mineralization of naphthalene was up to four times greater in treatments with actively grazing protozoa than in treatments containing the grazing inhibitor cytochalasin B. Control experiments confirmed that the grazing inhibitor was not toxic to ciliates but did prevent them from grazing. The grazing inhibitor did not affect growth rates of a mixed culture of sediment bacteria or a pure polycyclic-aromatic-hydrocarbon-degrading strain. Once grazing had been inhibited, supplementing treatments with inorganic N and P, glucose, or additional protozoa failed to stimulate naphthalene mineralization. Naphthalene-degrading bacteria were four to nine times less abundant when protozoan grazing was suppressed. We suggest that protozoa enhance naphthalene mineralization by selectively grazing on those sediment bacteria that ordinarily would outcompete naphthalene-degrading bacteria.

  15. The importance of marine sediment biodiversity in ecosystem precesses

    NARCIS (Netherlands)

    Snelgrove, P.V.R.; Blackburn, T.H.; Hutchings, P.; Alongi, D.M.; Grassle, J.F.; Hummel, H.; King, G.; Koike, I.; Lambshead, P.J.D.; Ramsing, N.B.; Solis-Weiss, V.

    1997-01-01

    Sedimentary habitats cover most of the ocean bottom and therefore constitute the largest. single ecosystem on earth in spatial coverage, Although only a small fraction of the micro-, meio- and macroscopic benthic organisms that reside in and on sediments have been described and few estimates of

  16. Wave Propagation in Granular Media Including Marine Sediments

    Science.gov (United States)

    2002-09-30

    involves the non-linear properties of the thin film of fluid separating adjacent grains. Intergranular interactions give rise to dissipation and dispersion...Sessarego, Laboratoire de Mecanique et d’Acoustique, C.N.R.S., Marseille, has a laboratory-based experimental program on acoustic waves in sediments. We

  17. 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....

  18. 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

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

    DEFF Research Database (Denmark)

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

    -structural properties suggesting that they are living electric micro cables. The mode of action of these organisms has major impacts on element cycling by redox processes, pH balances, mineral dissolution/precipitations, and electro migration of ions in marine sediment. The ability of Desulfubulbus filaments to bridge...... redox half-reactions in distant regions of the sediment leads to formation of electrical fields, which modifies ion transport. The local proton producing and proton consuming half reactions induces pH extremes that accelerate dissolution of iron sulphides and calcium carbonates in anoxic layers...... to 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....

  20. 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.

  1. Isolation strategies of marine-derived actinomycetes from sponge and sediment samples.

    Science.gov (United States)

    Hameş-Kocabaş, E Esin; Uzel, Ataç

    2012-03-01

    During the last two decades, discoveries of new members of actinomycetes and novel metabolites from marine environments have drawn attention to such environments, such as sediment and sponge. For the successful isolation of actinomycetes from marine environments, many factors including the use of enrichment and pre-treatment techniques, and the selection of growth media and antibiotic supplements should be taken into account. High-throughput cultivation is an innovative technique that mimics nature, eliminates undesired, fast-growing bacteria and creates suitable conditions for rare, slow-growing actinomycetes. This review comprehensively evaluates the traditional and innovative techniques and strategies used for the isolation of actinomycetes from marine sponge and sediment samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Sediment community responses to marine vs. terrigenous organic matter in a submarine canyon

    Directory of Open Access Journals (Sweden)

    W. R. Hunter

    2013-01-01

    Full Text Available The Whittard Canyon is a branching submarine canyon on the Celtic continental margin, which may act as a conduit for sediment and organic matter (OM transport from the European continental slope to the abyssal sea floor. In situ stable-isotope labelling experiments were conducted in the eastern and western branches of the Whittard Canyon, testing short-term (3–7 days responses of sediment communities to deposition of nitrogen-rich marine (Thalassiosira weissflogii and nitrogen-poor terrigenous (Triticum aestivum phytodetritus. 13C and 15N labels were traced into faunal biomass and bulk sediments, and the 13C label traced into bacterial polar lipid fatty acids (PLFAs. Isotopic labels penetrated to 5 cm sediment depth, with no differences between stations or experimental treatments (substrate or time. Macrofaunal assemblage structure differed between the eastern and western canyon branches. Following deposition of marine phytodetritus, no changes in macrofaunal feeding activity were observed between the eastern and western branches, with little change between 3 and 7 days. Macrofaunal C and N uptake was substantially lower following deposition of terrigenous phytodetritus with feeding activity governed by a strong N demand. Bacterial C uptake was greatest in the western branch of the Whittard Canyon, but feeding activity decreased between 3 and 7 days. Bacterial processing of marine and terrigenous OM were similar to the macrofauna in surficial (0–1 cm sediments. However, in deeper sediments bacteria utilised greater proportions of terrigenous OM. Bacterial biomass decreased following phytodetritus deposition and was negatively correlated to macrofaunal feeding activity. Consequently, this study suggests that macrofaunal–bacterial interactions influence benthic C cycling in the Whittard Canyon, resulting in differential fates for marine and terrigenous OM.

  3. Relevance of carbon stocks of marine sediments for national greenhouse gas inventories of maritime nations

    Directory of Open Access Journals (Sweden)

    Silvania Avelar

    2017-05-01

    Full Text Available Abstract Background Determining national carbon stocks is essential in the framework of ongoing climate change mitigation actions. Presently, assessment of carbon stocks in the context of greenhouse gas (GHG-reporting on a nation-by-nation basis focuses on the terrestrial realm, i.e., carbon held in living plant biomass and soils, and on potential changes in these stocks in response to anthropogenic activities. However, while the ocean and underlying sediments store substantial quantities of carbon, this pool is presently not considered in the context of national inventories. The ongoing disturbances to both terrestrial and marine ecosystems as a consequence of food production, pollution, climate change and other factors, as well as alteration of linkages and C-exchange between continental and oceanic realms, highlight the need for a better understanding of the quantity and vulnerability of carbon stocks in both systems. We present a preliminary comparison of the stocks of organic carbon held in continental margin sediments within the Exclusive Economic Zone of maritime nations with those in their soils. Our study focuses on Namibia, where there is a wealth of marine sediment data, and draws comparisons with sediment data from two other countries with different characteristics, which are Pakistan and the United Kingdom. Results Results indicate that marine sediment carbon stocks in maritime nations can be similar in magnitude to those of soils. Therefore, if human activities in these areas are managed, carbon stocks in the oceanic realm—particularly over continental margins—could be considered as part of national GHG inventories. Conclusions This study shows that marine sediment organic carbon stocks can be equal in size or exceed terrestrial carbon stocks of maritime nations. This provides motivation both for improved assessment of sedimentary carbon inventories and for reevaluation of the way that carbon stocks are assessed and valued. The

  4. Relevance of carbon stocks of marine sediments for national greenhouse gas inventories of maritime nations.

    Science.gov (United States)

    Avelar, Silvania; van der Voort, Tessa S; Eglinton, Timothy I

    2017-12-01

    Determining national carbon stocks is essential in the framework of ongoing climate change mitigation actions. Presently, assessment of carbon stocks in the context of greenhouse gas (GHG)-reporting on a nation-by-nation basis focuses on the terrestrial realm, i.e., carbon held in living plant biomass and soils, and on potential changes in these stocks in response to anthropogenic activities. However, while the ocean and underlying sediments store substantial quantities of carbon, this pool is presently not considered in the context of national inventories. The ongoing disturbances to both terrestrial and marine ecosystems as a consequence of food production, pollution, climate change and other factors, as well as alteration of linkages and C-exchange between continental and oceanic realms, highlight the need for a better understanding of the quantity and vulnerability of carbon stocks in both systems. We present a preliminary comparison of the stocks of organic carbon held in continental margin sediments within the Exclusive Economic Zone of maritime nations with those in their soils. Our study focuses on Namibia, where there is a wealth of marine sediment data, and draws comparisons with sediment data from two other countries with different characteristics, which are Pakistan and the United Kingdom. Results indicate that marine sediment carbon stocks in maritime nations can be similar in magnitude to those of soils. Therefore, if human activities in these areas are managed, carbon stocks in the oceanic realm-particularly over continental margins-could be considered as part of national GHG inventories. This study shows that marine sediment organic carbon stocks can be equal in size or exceed terrestrial carbon stocks of maritime nations. This provides motivation both for improved assessment of sedimentary carbon inventories and for reevaluation of the way that carbon stocks are assessed and valued. The latter carries potential implications for the management of

  5. Eukaryotic diversity in late Pleistocene marine sediments around a shallow methane hydrate deposit in the Japan Sea.

    Science.gov (United States)

    Kouduka, M; Tanabe, A S; Yamamoto, S; Yanagawa, K; Nakamura, Y; Akiba, F; Tomaru, H; Toju, H; Suzuki, Y

    2017-09-01

    Marine sediments contain eukaryotic DNA deposited from overlying water columns. However, a large proportion of deposited eukaryotic DNA is aerobically biodegraded in shallow marine sediments. Cold seep sediments are often anaerobic near the sediment-water interface, so eukaryotic DNA in such sediments is expected to be preserved. We investigated deeply buried marine sediments in the Japan Sea, where a methane hydrate deposit is associated with cold seeps. Quantitative PCR analysis revealed the reproducible recovery of eukaryotic DNA in marine sediments at depths up to 31.0 m in the vicinity of the methane hydrate deposit. In contrast, the reproducible recovery of eukaryotic DNA was limited to a shallow depth (8.3 m) in marine sediments not adjacent to the methane hydrate deposit in the same area. Pyrosequencing of an 18S rRNA gene variable region generated 1,276-3,307 reads per sample, which was sufficient to cover the biodiversity based on rarefaction curves. Phylogenetic analysis revealed that most of the eukaryotic DNA originated from radiolarian genera of the class Chaunacanthida, which have SrSO4 skeletons, the sea grass genus Zostera, and the seaweed genus Sargassum. Eukaryotic DNA originating from other planktonic fauna and land plants was also detected. Diatom sequences closely related to Thalassiosira spp., indicative of cold climates, were obtained from sediments deposited during the last glacial period (MIS-2). Plant sequences of the genera Alnus, Micromonas, and Ulmus were found in sediments deposited during the warm interstadial period (MIS-3). These results suggest the long-term persistence of eukaryotic DNA from terrestrial and aquatic sources in marine sediments associated with cold seeps, and that the genetic information from eukaryotic DNA from deeply buried marine sediments associated with cold seeps can be used to reconstruct environments and ecosystems from the past. © 2017 John Wiley & Sons Ltd.

  6. 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.

  7. Identification of Actinomycetes from Marine Sediments with ???Different Environmental Characteristics

    OpenAIRE

    Tahir, Akbar; Gosalam, Sulaiman

    2010-01-01

    Hibah Dikti 2009 ABSTRACT Research was conducted for inventing active substance from marine Actinomycetes having antiviral activities on tiger shrimp (Penaeus monodon) with particular interest on the White Spot Syndrome Virus (WSSV). The WSSV (namely: white spot disease) could cause a 100% mortalities in only 3 ??? 10 days post infection, hence, a massive loss for the shrimp farmers. Actinobacteria is a class of microorganism which commonly known as Actinomycetes and belong to the...

  8. Determination of cofactors in marine sediments; Bestimmung von Kofaktoren im marinen Sediment

    Energy Technology Data Exchange (ETDEWEB)

    Huschek, G.; Kayser, A.

    2002-12-01

    In respect to a sieving study of sediments in three different sediment locations (Wadden Sea (A), river Elbe-Aestuar (B), Baltic Sea (C)) a determination of selected organic compounds were carried out to study the influence of the sieving process on the variance of cofactors and analytical results. The organic pollutants PCB, Organochlorpesticides (OCP) and PAH were investigated in three fine sediment fractions <2 mm, > and < 63 {mu}m of the locations by accredited and standardised methods. At the same time the cofactor Organic Carbon (TOC) as well as Total Carbon (TC) and Total Nitrogen (TN) were determined in the fine sediment fractions. The endocrine disruptor Bisphenol A could be detected in the sediment locations B and C. The comparison of TOC, TC and TN average values by t-test showed significant differences between the fine fractions of location B and C. Because of low TOC values no signification was detectable in sediment A. The results show that the TOC values in fine sediments are affected by sieving. An enrichment of carbon was detected in the <63 {mu}m fraction in consideration of variance. A correlation between the cofactor TOC and the organic pollutant values could only be detected in the fine fractions of location B. The enrichment of pollutant values in the fine fractions was here analogue of TOC. For a comprehensive evaluation of the cofactor TOC no sufficient sieving sample materials were available in this study for location A and C. So a final statement regarding TOC in fine sediment fractions as a cofactor was not possible. The results show that a determination of organic contaminants in the fine sediment fraction <63 {mu}m make sense because of their enrichment in fine fractions in respect to the TOC values. (orig.)

  9. Sensitivity of the marine benthic copepod Tisbe biminiensis (copepoda, harpacticoida to potassium dichromate and sediment particle size

    Directory of Open Access Journals (Sweden)

    Cristiane M. V. Araújo-Castro

    2009-03-01

    Full Text Available For the future use of the marine benthic copepod Tisbe biminiensis in solid-phase sediment toxicological bioassays, the present study investigated the effect of muddy sediment from the Maracaípe estuary (northeastern Brazil, sediment particle size and the reference toxicant potassium dichromate on the species. Muddy sediment from Maracaípe can be used as control sediment, since it does not interfere in the copepod life-cycle and has metal contamination levels that are unlikely to produce any detrimental biological effects on benthic invertebrates. Neither survival nor fecundity was affected by grain size, suggesting that this species can be used with any kind of sediment from muddy to sandy. The sensitivity of T. biminiensis to K2Cr2O7 in acute tests was similar to that of other organisms. The LC50 (lethal concentration to 50% of the test organisms medium values for T. biminiensis were 7.51, 4.68 and 3.19 mg L-1 for Cr in 48, 72 and 96 h, respectively. These results suggest that T. biminiensis is a promising organism for use in solid-phase sediment toxicity assessments.Visando o uso futuro do copépodo marinho bentônico Tisbe biminiensis em bioensaios toxicológicos de sedimentos na fase sólida, o presente estudo investigou o efeito do sedimento lamoso do estuário de Maracaípe (Nordeste do Brasil. Foram considerados a granolometria e o tóxico de referência dicromato de potássio sobre a espécie. O sedimento lamoso de Maracaípe pode ser usado como controle, uma vez que não interfere no ciclo de vida do copépodo e possui níveis de contaminação de metais que não causariam efeitos biológicos em invertebrados bentônicos. Nem a sobrevivência ou fecundidade foi afetada pelo tamanho do grão, sugerindo que esta espécie pode ser usada com qualquer tipo de sedimento, de lama a areia. A sensibilidade de T. biminiensis ao K2Cr2O7 em testes agudos foi similar a de outros organismos. Os valores de CL50 (concentração letal a 50% dos

  10. Fungal communities from methane hydrate-bearing deep-sea marine sediments in South China Sea.

    Science.gov (United States)

    Lai, Xintian; Cao, Lixiang; Tan, Hongming; Fang, Shu; Huang, Yali; Zhou, Shining

    2007-12-01

    To elucidate fungal diversity in methane hydrate-bearing deep-sea marine sediments in the South China Sea, internal transcribed spacer (ITS) regions of rRNA genes from five different sediment DNA samples were amplified and phylogenetically analyzed. Total five ITS libraries were constructed and 413 clones selected randomly were grouped into 24 restriction patterns by Amplified Ribosomal DNA Restriction Analysis (ARDRA). ITS sequences of 44 representative clones were determined and compared with the GenBank database using gapped-BLAST. The phylogenetic analysis showed that the ITS sequences (71-97% similarity) were similar to those of Phoma, Lodderomyces, Malassezia, Cryptococcus, Cylindrocarpon, Hortaea, Pichia, Aspergillus and Candida. The remaining sequences were not associated to any known fungi or fungal sequences in the public database. The results suggested that methane hydrate-bearing deep-sea marine sediments harbor diverse fungi. This is the first report on fungal communities from methane hydrate-bearing deep-sea marine sediments in South China Sea.

  11. [Diversity and bioactivities of culturable marine actinobacteria isolated from mangrove sediment in Indian Ocean].

    Science.gov (United States)

    He, Jie; Zhang, Daofeng; Xu, Ying; Zhang, Xiaomei; Tang, Shukun; Xu, Lihua; Li, Wenjun

    2012-10-04

    In order to explore the diversity, antimicrobial activity and enzyme-producing activity of marine actinobacteria isolated from mangrove sediments in Indian Ocean. Eight sediments collected from mangrove sediments in Indian Ocean were treated by the plate dilution method and spread on 24 isolation media only containing sole carbon source for energy. Marine actinobacteria were isolated and identified by 16S rRNA gene sequence analysis. The antimicrobial activity and enzyme-producing activity of isolated strains were further detected by spot planting method. In total 139 representative strains were selected from 521 isolates, and they were further sequenced and performed phylogenetic analysis based on their 16S rRNA gene sequences. There were 35 strains identified as potential novel species. Antimicrobial activity was detected in Bacillus subtilis, Candida albicans, Escherichia coli, Staphylococcus aureus, Aspergillus niger. Enzyme-producing activity for protease cellulase, amylase and esterase were 36.5%, 26.5%, 22.4% and 15.9%, respectively. Diverse marine actinobacteria were discovered in mangrove sediment in Indian Ocean, which have antimicrobial and enzyme activity.

  12. Diversity of Oligotrichia and Choreotrichia Ciliates in Coastal Marine Sediments and in Overlying Plankton▿

    Science.gov (United States)

    Doherty, Mary; Tamura, Maiko; Vriezen, Jan A. C.; McManus, George B.; Katz, Laura A.

    2010-01-01

    Elucidating the relationship between ciliate communities in the benthos and the plankton is critical to understanding ciliate diversity in marine systems. Although data for many lineages are sparse, at least some members of the dominant marine ciliate clades Oligotrichia and Choreotrichia can be found in both plankton and benthos, in the latter either as cysts or active forms. In this study, we developed a molecular approach to address the relationship between the diversity of ciliates in the plankton and those of the underlying benthos in the same locations. Samples from plankton and sediments were compared across three sites along the New England coast, and additional subsamples were analyzed to assess reproducibility of methods. We found that sediment and plankton subsamples differed in their robustness to repeated subsampling. Sediment subsamples (i.e., 1-g aliquots from a single ∼20-g sample) gave variable estimates of diversity, while plankton subsamples produced consistent results. These results indicate the need for additional study to determine the spatial scale over which diversity varies in marine sediments. Clustering of phylogenetic types indicates that benthic assemblages of oligotrichs and choreotrichs appear to be more like those from spatially remote benthic communities than the ciliate communities sampled in the water above them. PMID:20435761

  13. Diversity of oligotrichia and choreotrichia ciliates in coastal marine sediments and in overlying plankton.

    Science.gov (United States)

    Doherty, Mary; Tamura, Maiko; Vriezen, Jan A C; McManus, George B; Katz, Laura A

    2010-06-01

    Elucidating the relationship between ciliate communities in the benthos and the plankton is critical to understanding ciliate diversity in marine systems. Although data for many lineages are sparse, at least some members of the dominant marine ciliate clades Oligotrichia and Choreotrichia can be found in both plankton and benthos, in the latter either as cysts or active forms. In this study, we developed a molecular approach to address the relationship between the diversity of ciliates in the plankton and those of the underlying benthos in the same locations. Samples from plankton and sediments were compared across three sites along the New England coast, and additional subsamples were analyzed to assess reproducibility of methods. We found that sediment and plankton subsamples differed in their robustness to repeated subsampling. Sediment subsamples (i.e., 1-g aliquots from a single approximately 20-g sample) gave variable estimates of diversity, while plankton subsamples produced consistent results. These results indicate the need for additional study to determine the spatial scale over which diversity varies in marine sediments. Clustering of phylogenetic types indicates that benthic assemblages of oligotrichs and choreotrichs appear to be more like those from spatially remote benthic communities than the ciliate communities sampled in the water above them.

  14. 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)

  15. Bioprospecting of Novel and Bioactive Compounds from Marine Actinomycetes Isolated from South China Sea Sediments.

    Science.gov (United States)

    Yang, Na; Song, Fuhang

    2018-02-01

    Marine actinomycetes are less investigated compared to terrestrial strains as potential sources of natural products. To date, few investigations have been performed on culturable actinomycetes associated with South China Sea sediments. In the present study, twenty-eight actinomycetes were recovered from South China Sea sediments after dereplication by traditional culture-dependent method. The 16S rRNA gene sequences analyses revealed that these strains related to five families and seven genera. Twelve representative strains possessed at least one of the biosynthetic genes coding for polyketide synthase I, II, and nonribosomal peptide synthetase. Four strains had anti-Mycobacterium phlei activities and five strains had activities against methicillin-resistant Staphylococcus aureus. 10 L-scale fermentation of strains Salinispora sp. NHF45, Nocardiopsis sp. NHF48, and Streptomyces sp. NHF86 were carried out for novel and bioactive compounds discovery. Finally, we obtained a novel α-pyrone compound from marine Nocardiopsis sp. NHF48, an analogue of paulomenol from marine Streptomyces sp. NHF86 and a new source of rifamycin B, produced by Salinispora sp. NHF45. The present study concluded that marine actinomycetes, which we isolated from South China Sea sediments, will be a suitable source for the development of novel and bioactive compounds.

  16. Biogeochemistry of Dissolved Free Amino Acids in Marine Sediments.

    Science.gov (United States)

    1980-09-01

    N C~l co LO~ - LLJC:0 C)D OD D -74- TABLE 3-3 Composition ot Insoluble Bacterial Proteina Amino Composition (mole %’) ACtd ChromobacteriumD...I \\I , ***ZJ0 ŕI~ 1 3 Il\\ "󈧘 3I o N ~3Q NO 2>0 I /301 / 40 I/ 50 I,, mMCO 4 8 2 16 4 I I I I I I I I I 0 400 800 1200 1600 2000 M ES = -95- Figure...amino acids appears to be very similar. This ques - tion, however, is important to the following discussion of sinks for DFAA in sediments. Therefore

  17. Ubiquitous presence and novel diversity of anaerobic alkane degraders in cold marine sediments

    Directory of Open Access Journals (Sweden)

    Antje eGittel

    2015-12-01

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

  18. Reconstruction of late Quaternary marine and terrestrial environmental conditions of Northwest Africa and Southeast Australia : a multiple organic proxy study using marine sediments

    NARCIS (Netherlands)

    Alfama Lopes dos Santos, R.

    2012-01-01

    NW Africa and SE Australia are regions which are particularly vulnerable to climate change. In this thesis, organic proxies are used from marine sediment cores to reconstruct past environmental conditions from these areas. In sediments from NW Africa, the UK'37 showed an efficient proxy for sea

  19. Magnetite diagenesis in marine sediments from the Oregon continental margin

    Science.gov (United States)

    Karlin, Robert

    1990-04-01

    The magnetochemistry of sediments from the Oregon continental margin is examined to determine the effects of iron-sulfur diagenesis on the paleomagnetic record. Magnetic mineral dissolution and transformation into iron sulfides are a common feature in these suboxic to anoxic lutites. These processes are evidenced in rapid decreases in natural remanent magnetization intensities and stabilities, systematic changes in other rock magnetic properties, and increases in solid phase sulfur concentrations with depth. Hysteresis measurements are used to evaluate downcore changes in magnetite concentration and grain size. Magnetite abundances decrease downcore from initial values of about 0.1%, and nominal grain diameters lie within a narrow pseudosingle domain range of 0.08 to 0.6 μm. A first-order surface area reaction model, dA/dt = -kA, is proposed to explain the magnetite dissolution mechanism, where A is the total magnetite surface area and k is the rate constant. The solution of this equation predicts that the surface area and concentration decrease exponentially, and the concentration, in addition, depends on grain size. Application of this model in two cores where grain size varies with depth successfully explains the downcore profiles of both concentration and surface area. Despite extensive magnetite destruction, magnetic directions in such sediments appear to reliably record long-wavelength trends of the geomagnetic field.

  20. Landslide-dammed paleolake perturbs marine sedimentation and drives genetic change in anadromous fish.

    Science.gov (United States)

    Mackey, Benjamin H; Roering, Joshua J; Lamb, Michael P

    2011-11-22

    Large bedrock landslides have been shown to modulate rates and processes of river activity by forming dams, forcing upstream aggradation of water and sediment, and generating catastrophic outburst floods. Less apparent is the effect of large landslide dams on river ecosystems and marine sedimentation. Combining analyses of 1-m resolution topographic data (acquired via airborne laser mapping) and field investigation, we present evidence for a large, landslide-dammed paleolake along the Eel River, CA. The landslide mass initiated from a high-relief, resistant outcrop which failed catastrophically, blocking the Eel River with an approximately 130-m-tall dam. Support for the resulting 55-km-long, 1.3-km(3) lake includes subtle shorelines cut into bounding terrain, deltas, and lacustrine sediments radiocarbon dated to 22.5 ka. The landslide provides an explanation for the recent genetic divergence of local anadromous (ocean-run) steelhead trout (Oncorhynchus mykiss) by blocking their migration route and causing gene flow between summer run and winter run reproductive ecotypes. Further, the dam arrested the prodigious flux of sediment down the Eel River; this cessation is recorded in marine sedimentary deposits as a 10-fold reduction in deposition rates of Eel-derived sediment and constitutes a rare example of a terrestrial event transmitted through the dispersal system and recorded offshore.

  1. Comparison of four chronic sediment toxicity tests using selected marine/estuarine tests species

    Energy Technology Data Exchange (ETDEWEB)

    Sims, I.; Fleming, R. [WRc Medmenham, Marlow (United Kingdom)

    1995-12-31

    Several draft standard guidelines exist for acute marine/estuarine sediment bioassays which measure lethality over a 4 to 14 day exposure period. Although these are very useful tools for certain applications, such tests may not be useful for discriminating between sediments with the low levels of contaminants most likely to be found in UK estuaries. For this application, chronic sediment bioassays are required which allow the measurement of both lethal and sublethal effects (growth, development and reproduction). Some chronic bioassays are currently being developed for estuarine sediments by workers in Europe, America and Canada. The objectives of the study presented here were to compare four bioassays, currently in development, in terms of their sensitivity to sediment-bound lindane and to differences in particle size. The test species selected for the study were Corophium volutator, Arenicola marina, Macoma Balthica and Neanthes arenaceodentata. Three sediment types were used: high, medium and low percentage of fine material, These were achieved using mixtures of silica sand and a fine, natural, estuarine sediment, and spiked with lindane using a spiking protocol developed at WRc. The results of the study will be presented.

  2. Photolytic Release of Dissolved Vanadium and Copper from Resuspended Coastal Marine Sediments

    Science.gov (United States)

    Skrabal, S. A.; Hammaker, S. N.; McBurney, A. W.; Avery, G. B., Jr.; Kieber, R. J.; Mead, R. N.

    2016-02-01

    Sunlight photolysis engenders release of dissolved vanadium (V), copper (Cu), and dissolved organic carbon (DOC) from a wide variety of resuspendable coastal marine sediments. Net photoreleases after 6 h of simulated sunlight were as high as 12 nM for Cu and as high as 15 nM for V. Release of Cu significantly correlated with sediment Cu. Photoreleased Cu (but not V) correlated with sediment Fe content, suggesting that photoreduction of Fe oxide carrier phases may be an important photoproduction mechanism for Cu. Longer term experiments showed continued release of metals that were not immediately readsorbed back onto sediments after 24 h of irradiation suggesting that photoproduced metals persist in the dissolved phase and are not immediately scavenged onto particles. Experiments utilizing differing total suspended sediment (TSS) levels show that, although higher TSS causes more photoproduction of Cu and V, the amount produced per mass of sediment is greatest at the lowest TSS. Vanadium photoproduction increased in Macondo oil-amended sediments compared to controls after a one-month incubation period suggesting that the oil may be a source of this metal to the water column. These results imply that photoproduction is an unrecognized source of the micronutrient metals Cu and V to coastal waters.

  3. 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.

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

    Directory of Open Access Journals (Sweden)

    Stephanie Ann Carr

    2015-08-01

    Full Text Available Bacteria belonging to the newly classified candidate phylum Atribacteria (formerly referred to as OP9 and JS1 are common in anoxic methane-rich sediments. However, the metabolic functions and biogeochemical role of these microorganisms in the subsurface remains unrealized due to the lack of pure culture representatives. In this study of deep sediment from Antarctica's Adélie Basin, collected during Expedition 318 of the Integrated Ocean Drilling Program (IODP, Atribacteria-related sequences of the 16S rRNA gene were abundant (up to 51% of the sequences and steadily increased in relative abundance with depth throughout the methane-rich zones. To better understand the metabolic potential of Atribacteria within this environment, and to compare with phylogenetically distinct Atribacteria from non-deep-sea environments, individual cells were sorted for single cell genomics from sediment collected from 97.41 meters below the seafloor from IODP Hole U1357C. As observed for non-marine Atribacteria, a partial single cell genome suggests a heterotrophic metabolism, with Atribacteria potentially producing fermentation products such as acetate, ethanol and CO2. These products may in turn support methanogens within the sediment microbial community and explain the frequent occurrence of Atribacteria in anoxic methane-rich sediments. This first report of a single cell genome from deep sediment broadens the known diversity within the Atribacteria phylum and highlights the potential role of Atribacteria in carbon cycling in deep sediment.

  5. Chemical and ancillary data associated with bed sediment, young of year Bluefish (Pomatomus saltatrix) tissue, and mussel (Mytilus edulis and Geukensia demissa) tissue collected after Hurricane Sandy in bays and estuaries of New Jersey and New York, 2013–14

    Science.gov (United States)

    Smalling, Kelly L.; Deshpande, Ashok D.; Blazer, Vicki; Galbraith, Heather S.; Dockum, Bruce W.; Romanok, Kristin M.; Colella, Kaitlyn; Deetz, Anna C.; Fisher, Irene J.; Imbrigiotta, Thomas E.; Sharack, Beth; Summer, Lisa; Timmons, DeMond; Trainor, John J.; Wieczorek, Daniel; Samson, Jennifer; Reilly, Timothy J.; Focazio, Michael J.

    2015-09-09

    This report describes the methods and data associated with a reconnaissance study of young of year bluefish and mussel tissue samples as well as bed sediment collected as bluefish habitat indicators during August 2013–April 2014 in New Jersey and New York following Hurricane Sandy in October 2012. This study was funded by the Disaster Relief Appropriations Act of 2013 (PL 113-2) and was conducted by the U.S. Geological Survey (USGS) in cooperation with the National Oceanic and Atmospheric Administration (NOAA).

  6. Thermophilic Sulfate-Reducing Bacteria in Cold Marine Sediment

    DEFF Research Database (Denmark)

    ISAKSEN, MF; BAK, F.; JØRGENSEN, BB

    1994-01-01

    Sulfate reduction was measured with the (SO42-)-S-35-tracer technique in slurries of sediment from Aarhus Bay, Denmark, where seasonal temperatures range from 0 degrees to 15 degrees C. The incubations were made at temperatures from 0 degrees C to 80 degrees C in temperature increments of 2 degrees...... C to search for presence of psychrophilic, mesophilic and thermophilic sulfate-reducing bacteria. Detectable activity was initially only in the mesophilic range, but after a lag phase sulfate reduction by thermophilic sulfate-reducing bacteria were observed. No distinct activity of psychrophilic...... sulfate-reducing bacteria was detected. Time course experiments showed constant sulfate reduction rates at 4 degrees C and 30 degrees C, whereas the activity at 60 degrees C increased exponentially after a lag period of one day. Thermophilic, endospore-forming sulfate-reducing bacteria, designated strain...

  7. {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.

  8. Anoxic Transformations of Radiolabeled Hydrogen-Sulfide in Marine and Fresh-Water Sediments

    DEFF Research Database (Denmark)

    ELSGAARD, L.; JØRGENSEN, BB

    1992-01-01

    oxidation to sulfate. Thiosulfate was partly turned over by oxidation or disproportionation and was found to be an intermediate in the (SO4=)-S-35 formation. The results demonstrate that oxidative and reductive sulfur cycling may occur simultaneously in marine and freshwater sediments. When added......Radiolabeled hydrogen sulfide (HS-)-S-35 was used to trace the anoxic sulfur transformations in marine and freshwater sediment slurries. Time course studies consistently showed a rapid (S2O3=)-S-35 formation and a progressive accumulation of (SO4=)-S-35 and thus indicated an anoxic sulfide...... as exogenous oxidant, nitrate (NO3-) stimulated the anoxic sulfide oxidation to sulfate. Ferric iron, added in the form of lepidocrocite (gamma-FeOOH), caused the precipitation of iron sulfides and only partial sulfide oxidation to pyrite and elemental sulfur....

  9. [Characteristics of Pahs pollution in sediments from Leizhou coastal marine area, Liusha Bay and Shenzhen Bay].

    Science.gov (United States)

    Zhao, Li-Rong; Sun, Sheng-Li; Ke, Sheng

    2012-04-01

    Leizhou coastal marine area, Liusha Bay and Shenzhen Bay represented open coastal area and half-closed bay, respectively. This study discussed the differences of PAHs concentration levels, spatial distribution and sources in sediments from these three marine areas. The results showed that detected ratios of 15 PAHs were 100%, and major compounds were 3-ring and 4-ring PAHs, especialy Phe, Fla, Pry and Bbf; Sigma PAHs concentration was Leizhou the outside, and the aquaculture > the non-aquaculture in Liusha Bay and Shenzhen Bay. It suggested that large-scale mariculture inside bay played an important role in PAHs pollution and might make it serious. Oil, fossil fuels and biomass burning were the dominant sources of PAHs in sediments from Leizhou coastal area, Liusha Bay and Shenzhen Bay.

  10. Bioprospecting from marine sediments of New Brunswick, Canada: exploring the relationship between total bacterial diversity and actinobacteria diversity

    National Research Council Canada - National Science Library

    Duncan, Katherine; Haltli, Bradley; Gill, Krista A; Kerr, Russell G

    2014-01-01

    .... In this study, we endeavored to determine if overall bacterial diversity in marine sediments, as determined by 16S rDNA amplicon pyrosequencing, could be correlated with culturable actinomycete...

  11. Seasonality and depth distribution of the abundance and activity of ammonia oxidizing microorganisms in marine coastal sediments (North Sea)

    NARCIS (Netherlands)

    Lipsewers, Y.A.; Bale, N.J.; Hopmans, E.C.; Schouten, S.; Sinninghe Damsté, J.S.; Villanueva, L.

    2014-01-01

    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

  12. Bulk Sediment and Diatom Silica Carbon Isotope Composition from Coastal Marine Sediments off East Antarctica

    NARCIS (Netherlands)

    Berg, S.; Leng, M.J.; Kendrick, C.P.; Cremer, H.; Wagner, B.

    2013-01-01

    Organic carbon occluded in diatom silica is assumed to be protected from degradation in the sediment. δ13C from diatom carbon (δ13C(diatom)) therefore potentially provides a signal of conditions during diatom growth. However, there have been few studies based on δ13C(diatom). Numerous variables can

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

    OpenAIRE

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

    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 and Janssand). The vertical distribution of DEN activity was examined using the acetylene inhibition technique combined with N2O microsensor measurements, whereas NH4+ production via DNRA w...

  14. 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

  15. Stereochemistry of amino acids in surface samples of a marine sediment

    Science.gov (United States)

    Pollock, G. E.; Kvenvolden, K. A.

    1978-01-01

    In two surface samples of marine sediment, the percentages of D-alanine and D-aspartic acid are significantly higher than the other D-amino acids and are similar to the range found in soils. The percentage of D-glutamic acid is also higher than the other amino acids but less than D-alanine and D-aspartic acid. These D-amino acids may come mainly from bacteria.

  16. 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.

  17. Distribution of non-marine diatoms in surface sediments of streams in Socotra Island, Yemen

    OpenAIRE

    Abdelfattah A. Zalat; Mohammed A. Al-Wosabi

    2011-01-01

    Abundance and species composition of non-marine benthic diatom assemblages were studied from surface sediments samples of 11 streams distributed in Socotra Island, located in the northwest Indian Ocean. A total of 145 diatom species, representing 44 genera, were identified. The overall diatom communities appear to be the first recorded off the island. Pennales and non-planktonic taxa were most dominant over centrales and planktonic forms, both in diversity of genera and species. The majority ...

  18. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Lebreiro, S. M.

    2013-06-01

    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. An inorganic geochemical argument for coupled anaerobic oxidation of methane and iron reduction in marine sediments.

    Science.gov (United States)

    Riedinger, N; Formolo, M J; Lyons, T W; Henkel, S; Beck, A; Kasten, S

    2014-03-01

    Here, we present results from sediments collected in the Argentine Basin, a non-steady state depositional marine system characterized by abundant oxidized iron within methane-rich layers due to sediment reworking followed by rapid deposition. Our comprehensive inorganic data set shows that iron reduction in these sulfate and sulfide-depleted sediments is best explained by a microbially mediated process-implicating anaerobic oxidation of methane coupled to iron reduction (Fe-AOM) as the most likely major mechanism. Although important in many modern marine environments, iron-driven AOM may not consume similar amounts of methane compared with sulfate-dependent AOM. Nevertheless, it may have broad impact on the deep biosphere and dominate both iron and methane cycling in sulfate-lean marine settings. Fe-AOM might have been particularly relevant in the Archean ocean, >2.5 billion years ago, known for its production and accumulation of iron oxides (in iron formations) in a biosphere likely replete with methane but low in sulfate. Methane at that time was a critical greenhouse gas capable of sustaining a habitable climate under relatively low solar luminosity, and relationships to iron cycling may have impacted if not dominated methane loss from the biosphere. © 2014 John Wiley & Sons Ltd.

  1. [Impacts of pH and surfactants on adsorption behaviors of norfloxacin on marine sediments].

    Science.gov (United States)

    Pang, Hui-Ling; Yang, Gui-Peng; Gao, Xian-Chi; Cao, Xiao-Yan

    2012-01-01

    The adsorption behaviors of norfloxacin (NOR) on marine sediments at different pH values and in the presence of four different surfactants were systematically investigated by a batch equilibrium method. The results indicated that Freundlich adsorption isotherms fitted the adsorption behavior of NOR on marine sediments very well at different pH values. The Freundlich constant K(F) and the equilibrium adsorption amount of NOR reduced with the increase of pH values, and the minimum appeared at pH 8.10. The results suggested that cation exchange was the main adsorption mechanism of NOR at pH 6.01, while Van der Waals' force, hydrophobic effects, electrostatic force were the major adsorption mechanism of NOR on marine sediments at pH 8.10. The adsorption process fitted well with pseudo-second-order kinetic equations with the addition of surfactants. Our study also indicated that the addition of surfactants had the significant influence on the saturated adsorption amount of adsorption of NOR. The equilibrium adsorption amount (Q(e)) of NOR exhibited the following sequence: Q(e) (Tween80) < Q(e) (Tween20)

  2. Seasonal and spatial diversity of microbial communities in marine sediments of the South China Sea.

    Science.gov (United States)

    Du, Jikun; Xiao, Kai; Huang, Yali; Li, Huixian; Tan, Hongming; Cao, Lixiang; Lu, Yongjun; Zhou, Shining

    2011-10-01

    This study was conducted to characterize the diversity of microbial communities in marine sediments of the South China Sea by means of 16S rRNA gene clone libraries. The results revealed that the sediment samples collected in summer harboured a more diverse microbial community than that collected in winter, Deltaproteobacteria dominated 16S rRNA gene clone libraries from both seasons, followed by Gammaproteobacteria, Acidobacteria, Nitrospirae, Planctomycetes, Firmicutes. Archaea phylotypes were also found. The majority of clone sequences shared greatest similarity to uncultured organisms, mainly from hydrothermal sediments and cold seep sediments. In addition, the sedimentary microbial communities in the coastal sea appears to be much more diverse than that of the open sea. A spatial pattern in the sediment samples was observed that the sediment samples collected from the coastal sea and the open sea clustered separately, a novel microbial community dominated the open sea. The data indicate that changes in environmental conditions are accompanied by significant variations in diversity of microbial communities at the South China Sea.

  3. 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 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)).

  4. Quantification of petrogenic PAH in marine sediment using molecular stable carbon isotopic ratio measurement

    Energy Technology Data Exchange (ETDEWEB)

    Mazeas, L.; Budzinski, H. [Bordeaux-1 Univ., 33 - Talence (France). Laboratoire de Physico- et Toxico-Chimie des Systemes Naturels

    1999-04-01

    Compound-specific carbon isotope analyses were performed on polycyclic aromatic hydrocarbons (phenanthrene and methyl-phenanthrene) isolated from marine sediments contaminated with petroleum. Isotopic composition measurements of individual methyl-phenanthrene were subject to important uncertainties because they were not completely separated by gas chromatographic separation. Nevertheless the isotopic composition of the sum of methyl-phenanthrene was measured with good reproducibility. As petrogenic PAHs and PAHs present in the sediment before the petroleum contamination have different isotopic compositions it was possible to quantitatively source apportion methyl-phenanthrene in contaminated sediment with a good precision and reliability, using the isotopic composition of the sum of methyl-phenanthrene and a simple mass balance calculation. (authors) 10 refs.

  5. Screening of secondary metabolite biosynthesis genes of marine actinomycetes isolated from Trabzon (Black Sea sea sediments

    Directory of Open Access Journals (Sweden)

    Kadriye Özcan

    2017-06-01

    Full Text Available In this study, active secondary metabolite production capacity of actinomycete isolates obtained from Trabzon (Black Sea sea sediments was investigated by molecular techniques. Totaly 24 actinomycetes were investigated by PCR based on the presence of secondary metabolite biosynthesis genes PKS / NRPS. According to the PCR results, 25 and 58% of actinomycetes obtained from Trabzon sea sediments were found to contain PKS-NRPS and only NRPS gene regions, respectively. When PCR data were evaluated, it was found that the production of the peptide form active secondary metabolite of the isolates by non-ribosomal way was higher than that of the secondary metabolite production by the PKS pathway. In addition, it has been determined that Black Sea marine sediments have high potential for active secondary metabolite production.

  6. Petroleum hydrocarbon concentrations in marine sediments along Nagapattinam - Pondicherry coastal waters, Southeast coast of India.

    Science.gov (United States)

    Kamalakannan, K; Balakrishnan, S; Sampathkumar, P

    2017-04-15

    In this present study, petroleum hydrocarbons were statistically analyzed in three different coastal sediment cores viz., (N1, P1 and P2) from the Southeast coast of Tamil Nadu, India to examine the viability of PHCs. The significant positive relationship between mud (silt+clay+sand) and PHC unveiled that high specific surface of area of mud content raise the level of PHCs. Cluster analysis was used to discriminate the sediment samples based on their degree of contamination. The present study shows that instead of expensive and destructive PHC chemical methods, magnetic susceptibility is found to be a suitable, cheap and rapid method for detailed study of PHC in marine sediments. This baseline PHCs data can be used for regular ecological monitoring and effective management for the mining and tourism related activities in the coastal ecosystem. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  7. Anthropogenic Forcing of Carbonate and Organic Carbon Preservation in Marine Sediments

    Science.gov (United States)

    Keil, Richard

    2017-01-01

    Carbon preservation in marine sediments, supplemented by that in large lakes, is the primary mechanism that moves carbon from the active surficial carbon cycle to the slower geologic carbon cycle. Preservation rates are low relative to the rates at which carbon moves between surface pools, which has led to the preservation term largely being ignored when evaluating anthropogenic forcing of the global carbon cycle. However, a variety of anthropogenic drivers—including ocean warming, deoxygenation, and acidification, as well as human-induced changes in sediment delivery to the ocean and mixing and irrigation of continental margin sediments—all work to decrease the already small carbon preservation term. These drivers affect the cycling of both carbonate and organic carbon in the ocean. The overall effect of anthropogenic forcing in the modern ocean is to decrease delivery of carbon to sediments, increase sedimentary dissolution and remineralization, and subsequently decrease overall carbon preservation.

  8. Molecular tools to understand the bioremediation effect of plants and earthworms on contaminated marine sediments.

    Science.gov (United States)

    Moreno, Beatriz; Cañizares, Rosa; Macci, Cristina; Doni, Serena; Masciandaro, Grazia; Benitez, Emilio

    2015-12-30

    A meso-scale pilot plant was set up to test the efficiency of a bioremediation scheme applied to marine sediments contaminated by heavy metals and hydrocarbons. The experiment was implemented for three years in two stages using two remediation agents: plants (Paspalum vaginatum and Tamarix gallica) and earthworms (Eisenia fetida). DNA and RNA-based methodologies were applied to elucidate the dynamics of the bacterial population and were related to improving biological and chemical conditions of the sediments. Bioremediation strategies were successful in removing pollutants from the contaminated sediments and specialization within the bacterial community related to the type of contamination present was detected in the different stages of the process. The highest response of Gram-positive PAH-degraders to the contamination was detected at the beginning and after the first stage of the experiment, corresponding to the uppermost values of degradation. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. 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)

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

    Science.gov (United States)

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

    2013-08-08

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

  11. Phylogenetic Characterization of Marine Benthic Archaea in Organic-Poor Sediments of the Eastern Equatorial Pacific Ocean (ODP Site 1225

    Directory of Open Access Journals (Sweden)

    Antje Lauer

    2016-09-01

    Full Text Available Sequencing surveys of microbial communities in marine subsurface sediments have focused on organic-rich, continental margins; the database for organic-lean deep-sea sediments from mid-ocean regions is underdeveloped. The archaeal community in subsurface sediments of ODP Site 1225 in the eastern equatorial Pacific (3760 m water depth; 1.1 and 7.8 m sediment depth was analyzed by PCR, cloning and sequencing, and by denaturant gradient gel electrophoresis (DGGE of 16S rRNA genes. Three uncultured archaeal lineages with different depth distributions were found: Marine Group I (MG-I within the Thaumarchaeota, its sister lineage Marine Benthic Group A (MBG-A, the phylum-level archaeal lineage Marine Benthic Group B (also known as Deep-Sea Archaeal Group or Lokiarchaeota, and the Deep-Sea Euryarchaeotal Group 3. The MG-I phylotypes included representatives of sediment clusters that are distinct from the pelagic members of this phylum. On the scale from fully oxidized, extremely organic carbon-depleted sediments (for example, those the South Pacific Gyre to fully reduced, organic carbon-rich marine subsurface sediments (such as those of the Peru Margin, Ocean Drilling Program (ODP Site 1225 falls into the non-extreme organic carbon-lean category, and harbors archaeal communities from both ends of the spectrum.

  12. 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

  13. Quantitative molecular analysis of the microbial community in marine arctic sediments (Svalbard).

    Science.gov (United States)

    Ravenschlag, K; Sahm, K; Amann, R

    2001-01-01

    Fluorescence in situ hybridization (FISH) and rRNA slot blot hybridization with 16S rRNA-targeted oligonucleotide probes were used to investigate the phylogenetic composition of a marine Arctic sediment (Svalbard). FISH resulted in the detection of a large fraction of microbes living in the top 5 cm of the sediment. Up to 65.4% +/- 7.5% of total DAPI (4',6'-diamidino-2-phenylindole) cell counts hybridized to the bacterial probe EUB338, and up to 4.9% +/- 1.5% hybridized to the archaeal probe ARCH915. Besides delta-proteobacterial sulfate-reducing bacteria (up to 16% 52) members of the Cytophaga-Flavobacterium cluster were the most abundant group detected in this sediment, accounting for up to 12.8% of total DAPI cell counts and up to 6.1% of prokaryotic rRNA. Furthermore, members of the order Planctomycetales accounted for up to 3.9% of total cell counts. In accordance with previous studies, these findings support the hypothesis that these bacterial groups are not simply settling with organic matter from the pelagic zone but are indigenous to the anoxic zones of marine sediments. Members of the gamma-proteobacteria also constituted a significant fraction in this sediment (6.1% +/- 2.5% of total cell counts, 14.4% +/- 3.6% of prokaryotic rRNA). A new probe (GAM660) specific for sequences affiliated with free-living or endosymbiotic sulfur-oxidizing bacteria was developed. A significant number of cells was detected by this probe (2.1% +/- 0.7% of total DAPI cell counts, 13.2% +/- 4. 6% of prokaryotic rRNA), showing no clear zonation along the vertical profile. Gram-positive bacteria and the beta-proteobacteria were near the detection limit in all sediments.

  14. 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.

  15. Nucleation and growth of todorokite from birnessite: Implications for trace-metal cycling in marine sediments

    Science.gov (United States)

    Atkins, Amy L.; Shaw, Samuel; Peacock, Caroline L.

    2014-11-01

    The phyllomanganate birnessite is the main Mn-bearing phase in oxic marine sediments, and through coupled sorption and redox exerts a strong control on the oceanic concentration of micronutrient trace metals. However, under diagenesis and mild hydrothermal conditions, birnessite undergoes transformation to the tectomanganate todorokite. The mechanistic details of this transformation are important for the speciation and mobility of metals sequestered by birnessite, and are necessary in order to quantify the role of marine sediments in global trace element cycles. Here we transform a synthetic, poorly crystalline, hexagonal birnessite, analogous to marine birnessite, into todorokite under a mild reflux procedure, developed to mimic marine diagenesis and mild hydrothermal conditions. We characterize our birnessite and reflux products as a time series, employing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), BET surface area analysis, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM) and extended X-ray absorption fine structure spectroscopy (EXAFS). We provide new insight into the crystallization pathway and mechanism of todorokite formation from birnessite under conditions analogous to those found in marine diagenetic and hydrothermal settings. Specifically we propose a new four-stage process for the transformation of birnessite to todorokite, beginning with todorokite nucleation, then crystal growth from solution to form todorokite primary particles, followed by their self-assembly and oriented growth via oriented attachment to form crystalline todorokite laths, culminating in traditional crystal ripening. We suggest that, contrary to current understanding, trace metals like Ni might retard the transformation of birnessite to todorokite and be released to marine sedimentary pore-waters during this diagenetic process, thus potentially providing a benthic flux of these micronutrients to seawater.

  16. Causes for negative carbon isotope anomalies in Mesozoic marine sediments : Constraints from modern and ancient anoxic settings

    NARCIS (Netherlands)

    Breugel, Y. van

    2006-01-01

    Oceanic Anoxic Events (OAEs) were short periods in Earth history (˜0.5-1 Ma) characterized by atypically high burial rates of organic carbon in marine sediments worldwide. OAEs reflect increased marine primary production and/or enhanced organic matter preservation under anoxic water column

  17. Causes for negative carbon isotope anomalies in Mesozoic marine sediments: Constraints from modern and ancient anoxic settings

    NARCIS (Netherlands)

    van Breugel, Y.

    2006-01-01

    Oceanic Anoxic Events (OAEs) were short periods in Earth history (˜0.5-1 Ma) characterized by atypically high burial rates of organic carbon in marine sediments worldwide. OAEs reflect increased marine primary production and/or enhanced organic matter preservation under anoxic water column

  18. Performance evaluation of nitrogen isotope ratio determination in marine and lacustrine sediments: An inter-laboratory comparison

    NARCIS (Netherlands)

    Bahlmann, E.; Bernasconi, S.M.; Bouillon, S.; Houtekamer, M.; Korntheuer, M.; Langenberg, F.; Mayr, C.; Metzke, M.; Middelburg, J.J.; Nagel, B.; Struck, U.; Voß, M.; Emeis, K.C.

    2010-01-01

    Nitrogen isotopes of organic matter are increasingly studied in marine biogeochemistry and geology, plant and animal ecology, and paleoceanography. Here, we present results of an inter-laboratory test on determination of nitrogen isotope ratios in marine and lacustrine sediments. Six different

  19. Chemoautotrophic carbon fixation rates and active bacterial communities in intertidal marine sediments.

    Directory of Open Access Journals (Sweden)

    Henricus T S Boschker

    Full Text Available Chemoautotrophy has been little studied in typical coastal marine sediments, but may be an important component of carbon recycling as intense anaerobic mineralization processes in these sediments lead to accumulation of high amounts of reduced compounds, such as sulfides and ammonium. We studied chemoautotrophy by measuring dark-fixation of 13C-bicarbonate into phospholipid derived fatty acid (PLFA biomarkers at two coastal sediment sites with contrasting sulfur chemistry in the Eastern Scheldt estuary, The Netherlands. At one site where free sulfide accumulated in the pore water right to the top of the sediment, PLFA labeling was restricted to compounds typically found in sulfur and ammonium oxidizing bacteria. At the other site, with no detectable free sulfide in the pore water, a very different PLFA labeling pattern was found with high amounts of label in branched i- and a-PLFA besides the typical compounds for sulfur and ammonium oxidizing bacteria. This suggests that other types of chemoautotrophic bacteria were also active, most likely Deltaproteobacteria related to sulfate reducers. Maximum rates of chemoautotrophy were detected in first 1 to 2 centimeters of both sediments and chemosynthetic biomass production was high ranging from 3 to 36 mmol C m(-2 d(-1. Average dark carbon fixation to sediment oxygen uptake ratios were 0.22±0.07 mol C (mol O2(-1, which is in the range of the maximum growth yields reported for sulfur oxidizing bacteria indicating highly efficient growth. Chemoautotrophic biomass production was similar to carbon mineralization rates in the top of the free sulfide site, suggesting that chemoautotrophic bacteria could play a crucial role in the microbial food web and labeling in eukaryotic poly-unsaturated PLFA was indeed detectable. Our study shows that dark carbon fixation by chemoautotrophic bacteria is a major process in the carbon cycle of coastal sediments, and should therefore receive more attention in future

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

    Science.gov (United States)

    Boschker, Henricus T. S.; Vasquez-Cardenas, Diana; Bolhuis, Henk; Moerdijk-Poortvliet, Tanja W. C.; Moodley, Leon

    2014-01-01

    Chemoautotrophy has been little studied in typical coastal marine sediments, but may be an important component of carbon recycling as intense anaerobic mineralization processes in these sediments lead to accumulation of high amounts of reduced compounds, such as sulfides and ammonium. We studied chemoautotrophy by measuring dark-fixation of 13C-bicarbonate into phospholipid derived fatty acid (PLFA) biomarkers at two coastal sediment sites with contrasting sulfur chemistry in the Eastern Scheldt estuary, the Netherlands. At one site where free sulfide accumulated in the pore water right to the top of the sediment, PLFA labeling was restricted to compounds typically found in sulfur and ammonium oxidizing bacteria. At the other site, with no detectable free sulfide in the pore water, a very different PLFA labeling pattern was found with high amounts of label in branched i- and a-PLFA besides the typical compounds for sulfur and ammonium oxidizing bacteria. This suggests that other types of chemoautotrophic bacteria were also active, most likely Deltaproteobacteria related to sulfate reducers. Maximum rates of chemoautotrophy were detected in first 1 to 2 centimeters of both sediments and chemosynthetic biomass production was high ranging from 3 to 36 mmol C m−2 d−1. Average dark carbon fixation to sediment oxygen uptake ratios were 0.22±0.07 mol C (mol O2)−1, which is in the range of the maximum growth yields reported for sulfur oxidizing bacteria indicating highly efficient growth. Chemoautotrophic biomass production was similar to carbon mineralization rates in the top of the free sulfide site, suggesting that chemoautotrophic bacteria could play a crucial role in the microbial food web and labeling in eukaryotic poly-unsaturated PLFA was indeed detectable. Our study shows that dark carbon fixation by chemoautotrophic bacteria is a major process in the carbon cycle of coastal sediments, and should therefore receive more attention in future studies on

  1. Phytane from chemolytic analysis of modern marine sediments: A product of desulfurization or not?

    Science.gov (United States)

    Prahl, F. G.; Pinto, L. A.; Sparrow, M. A.

    1996-03-01

    A set of modern marine sediments was analyzed to evaluate the role of sulfurization as a mechanism for biomarker preservation during early diagenesis. The set consisted of sediments accumulating within various oxic to anoxic depositional environments. Raney nickel treatment of the polar fraction of total extractable lipids (pTEL) from each sample yielded 3,7,11,15-tetramethylhexadecane ('phytane') as the dominant product, accompanied in several cases by minor levels of C 27, C 28, and C 29 5 α/ β(H)-steranes, n-C 31 alkane, and β-carotane. Although others have ascribed such products to a desulfurization reaction, our work reveals significant production of phytane from the action of Raney nickel on the esterified side chain of chlorophyll. Results suggest that catalytic dehydration/hydrogenation of chlorophyll accounts for ~50 and ~4% of the Raney nickel phytane (rnPhy) yield measured in suboxic sediments from the Washington shelf and anoxic sediments from Saanich Inlet, respectively. If 8-20% of the pheopigment detected in the suboxic sediments and all of the pheopigment detected in the anoxic sediment exists as pheophytin, the catalytic dehydration/hydrogenation process would account for 100 and 50%, respectively, of the observed rnPhy yield. The collective findings from our work underscore the necessity to exercise extreme caution when interpreting the geochemical significance of hydrocarbon products from Raney nickel treatment of pTEL from sediments. Despite the organic chemical fact that Raney nickel is a well-known desulfurizing agent, desulfurization cannot be assigned necessarily as the source of hydrocarbons generated by the action of this reagent on complex lipid extracts from sediments, particularly those from modern environments.

  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. Mineralogy, early marine diagenesis, and the chemistry of shallow-water carbonate sediments

    Science.gov (United States)

    Higgins, J. A.; Blättler, C. L.; Lundstrom, E. A.; Santiago-Ramos, D. P.; Akhtar, A. A.; Crüger Ahm, A.-S.; Bialik, O.; Holmden, C.; Bradbury, H.; Murray, S. T.; Swart, P. K.

    2018-01-01

    Shallow-water carbonate sediments constitute the bulk of sedimentary carbonates in the geologic record and are widely used archives of Earth's chemical and climatic history. One of the main limitations in interpreting the geochemistry of ancient carbonate sediments is the potential for post-depositional diagenetic alteration. In this study, we use paired measurements of calcium (44Ca/40Ca or δ44Ca) and magnesium (26Mg/24Mg or δ26Mg) isotope ratios in sedimentary carbonates and associated pore-fluids as a tool to understand the mineralogical and diagenetic history of Neogene shallow-water carbonate sediments from the Bahamas and southwest Australia. We find that the Ca and Mg isotopic composition of bulk carbonate sediments at these sites exhibits systematic stratigraphic variability that is related to both mineralogy and early marine diagenesis. The observed variability in bulk sediment Ca isotopes is best explained by changes in the extent and style of early marine diagenesis from one where the composition of the diagenetic carbonate mineral is determined by the chemistry of the fluid (fluid-buffered) to one where the composition of the diagenetic carbonate mineral is determined by the chemistry of the precursor sediment (sediment-buffered). Our results indicate that this process, together with variations in carbonate mineralogy (aragonite, calcite, and dolomite), plays a fundamental and underappreciated role in determining the regional and global stratigraphic expressions of geochemical tracers (δ13C, δ18O, major, minor, and trace elements) in shallow-water carbonate sediments in the geologic record. Our results also provide evidence that a large shallow-water carbonate sink that is enriched in 44Ca can explain the mismatch between the δ44/40Ca value of rivers and deep-sea carbonate sediments and call into question the hypothesis that the δ44/40Ca value of seawater depends on the mineralogy of primary carbonate precipitations (e.g. 'aragonite seas' and

  4. Diversity of Nonribosomal Peptide Synthetase Genes in the AnticancerProducing Actinomycetes Isolated from Marine Sediment in Indonesia

    OpenAIRE

    Camelia Herdini; Shinta Hartanto; Sofia Mubarika; Bambang Hariwiyanto; Nastiti Wijayanti; Akira Hosoyama; Atsushi Yamazoe; Hideaki Nojiri; Jaka Widada

    2016-01-01

    Marine actinomycetes is a group of bacteria that is highly potential in producing novel bioactive compound. It has unique characteristics and is different from other terrestrial ones. Extreme environmental condition is suspected to lead marine actinomycetes produce different types of bioactive compound found previously. The aim of this study was to explore the presence and diversity of NRPS genes in 14 anticancer-producing actinomycetes isolated from marine sediment in Indonesia. ...

  5. Estimation of the global inventory of methane hydrates in marine sediments using transfer functions

    Directory of Open Access Journals (Sweden)

    E. Piñero

    2013-02-01

    Full Text Available The accumulation of gas hydrates in marine sediments is essentially controlled by the accumulation of particulate organic carbon (POC which is microbially converted into methane, the thickness of the gas hydrate stability zone (GHSZ where methane can be trapped, the sedimentation rate (SR that controls the time that POC and the generated methane stays within the GHSZ, and the delivery of methane from deep-seated sediments by ascending pore fluids and gas into the GHSZ. Recently, Wallmann et al. (2012 presented transfer functions to predict the gas hydrate inventory in diffusion-controlled geological systems based on SR, POC and GHSZ thickness for two different scenarios: normal and full compacting sediments. We apply these functions to global data sets of bathymetry, heat flow, seafloor temperature, POC input and SR, estimating a global mass of carbon stored in marine methane hydrates from 3 to 455 Gt of carbon (GtC depending on the sedimentation and compaction conditions. The global sediment volume of the GHSZ in continental margins is estimated to be 60–67 × 1015 m3, with a total of 7 × 1015 m3 of pore volume (available for GH accumulation. However, seepage of methane-rich fluids is known to have a pronounced effect on gas hydrate accumulation. Therefore, we carried out a set of systematic model runs with the transport-reaction code in order to derive an extended transfer function explicitly considering upward fluid advection. Using averaged fluid velocities for active margins, which were derived from mass balance considerations, this extended transfer function predicts the enhanced gas hydrate accumulation along the continental margins worldwide. Different scenarios were investigated resulting in a global mass of sub-seafloor gas hydrates of ~ 550 GtC. Overall, our systematic approach allows to clearly and quantitatively distinguish between the effect of biogenic methane generation from POC and

  6. Sediment Mediated Marine-derived Nutrient Transfers in Watersheds: the Dirt on Salmon Decay Products

    Science.gov (United States)

    Petticrew, Ellen; Albers, Sam

    2014-05-01

    The conveyance of nutrients and contaminants through aquatic systems is typically mediated by inorganic fine sediment. Its influence on the transfer of marine-derived nutrients through watersheds, however, is less well acknowledged. The ecological impact of the annual pulse of marine-derived nutrients (MDN) moved upstream into interior river systems via migrating salmon is thought to be significant as both local spawning reaches and the downstream nursery lakes have evidenced increased productivity following this nutrient pulse. The relationship between the number of upstream spawners and productivity in downstream nursery lakes is poorly defined as the conveyance of MDN between the two points of interest is influenced spatially and temporally by both channel and lake processes. A research project that specifically investigates the association between salmon decay products and sediment mediated transfers of these marine-derived nutrients downstream to the nursery lake is underway in the Horsefly River in British Columbia, an important sockeye river tributary to Quesnel Lake in the Canada's Fraser River watershed. Results from sampling freshet delivery to the lake in 2011 and 2012 will be presented as they represent two end members of the four year spawning cycle - snowmelt flushing following a high and low spawner return year. A continuous flow centrifuge was used to collect bulk suspended sediment 1) at points along the river, downstream of the spawning grounds, 2) along a transect from the river mouth where it enters Horsefly Bay and 3) at several other locations in the river plume during spring freshet. Stable isotopes (13C and 15N) were used to detect the MDN and chlorophyll a was analyzed to represent water column primary production. The relationships between sediment loads, nutrient delivery to the lake and primary productivity during this period will be presented in the context of upstream spawner biomass for both years.

  7. Spatial, temporal, and source variations of hydrocarbons in marine sediments from Baffin Bay, Eastern Canadian Arctic.

    Science.gov (United States)

    Foster, Karen L; Stern, Gary A; Carrie, Jesse; Bailey, Joscelyn N-L; Outridge, Peter M; Sanei, Hamed; Macdonald, Robie W

    2015-02-15

    With declining sea ice conditions in Arctic regions owing to changing climate, the large prospective reservoirs of oil and gas in Baffin Bay and Davis Strait are increasingly accessible, and the interest in offshore exploration and shipping through these regions has increased. Both of these activities are associated with the risk of hydrocarbon releases into the marine ecosystem. However, hydrocarbons are also present naturally in marine environments, in some cases deriving from oil seeps. We have analyzed hydrocarbon concentrations in eleven sediment cores collected from northern Baffin Bay during 2008 and 2009 Amundsen expeditions and have examined the hydrocarbon compositions in both pre- and post-industrial periods (i.e., before and after 1900) to assess the sources of hydrocarbons, and their temporal and spatial variabilities. Concentrations of ΣPAHs ranged from 341 to 2693 ng g(-1) dw, with concentrations in cores from sites within the North Water (NOW) Polynya generally higher. Individual PAH concentrations did not exceed concentrations of concern for marine aquatic life, with one exception found in a core collected within the NOW (one of the seven sediment core samples). Hydrocarbon biomarkers, including alkane profiles, OEP (odd-to-even preference), and TAR (terrigenous/aquatic ratios) values indicated that organic carbon at all sites is derived from both terrigenous higher plants and marine algae, the former being of greater significance at coastal sites, and the latter at the deepest sites at the southern boundary of the NOW. Biomarker ratios and chemical profiles indicate that petrogenic sources dominate over combustion sources, and thus long-range atmospheric transport is less significant than inputs from weathering. Present-day and historic pre-1900 hydrocarbon concentrations exhibited less than an order of magnitude difference for most compounds at all sites. The dataset presented here provides a baseline record of hydrocarbon concentrations in

  8. Trace element storage capacity of sediments in dead Posidonia oceanica mat from a chronically contaminated marine ecosystem.

    Science.gov (United States)

    Di Leonardo, Rossella; Mazzola, Antonio; Cundy, Andrew B; Tramati, Cecilia Doriana; Vizzini, Salvatrice

    2017-01-01

    Posidonia oceanica mat is considered a long-term bioindicator of contamination. Storage and sequestration of trace elements and organic carbon (Corg ) were assessed in dead P. oceanica mat and bare sediments from a highly polluted coastal marine area (Augusta Bay, central Mediterranean). Sediment elemental composition and sources of organic matter have been altered since the 1950s. Dead P. oceanica mat displayed a greater ability to bury and store trace elements and Corg than nearby bare sediments, acting as a long-term contaminant sink over the past 120 yr. Trace elements, probably associated with the mineral fraction, were stabilized and trapped despite die-off of the overlying P. oceanica meadow. Mat deposits registered historic contamination phases well, confirming their role as natural archives for recording trace element trends in marine coastal environments. This sediment typology is enriched with seagrass-derived refractory organic matter, which acts mainly as a diluent of trace elements. Bare sediments showed evidence of inwash of contaminated sediments via reworking; more rapid and irregular sediment accumulation; and, because of the high proportions of labile organic matter, a greater capacity to store trace elements. Through different processes, both sediment typologies represent a repository for chemicals and may pose a risk to the marine ecosystem as a secondary source of contaminants in the case of sediment dredging or erosion. Environ Toxicol Chem 2017;36:49-58. © 2016 SETAC. © 2016 SETAC.

  9. 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. Copyright© by the Spanish Society for Microbiology and Institute for Catalan Studies.

  10. Microbial Communities from Methane Hydrate-Bearing Deep Marine Sediments in a Forearc Basin

    Science.gov (United States)

    Reed, David W.; Fujita, Yoshiko; Delwiche, Mark E.; Blackwelder, D. Brad; Sheridan, Peter P.; Uchida, Takashi; Colwell, Frederick S.

    2002-01-01

    Microbial communities in cores obtained from methane hydrate-bearing deep marine sediments (down to more than 300 m below the seafloor) in the forearc basin of the Nankai Trough near Japan were characterized with cultivation-dependent and -independent techniques. Acridine orange direct count data indicated that cell numbers generally decreased with sediment depth. Lipid biomarker analyses indicated the presence of viable biomass at concentrations greater than previously reported for terrestrial subsurface environments at similar depths. Archaeal lipids were more abundant than bacterial lipids. Methane was produced from both acetate and hydrogen in enrichments inoculated with sediment from all depths evaluated, at both 10 and 35°C. Characterization of 16S rRNA genes amplified from the sediments indicated that archaeal clones could be discretely grouped within the Euryarchaeota and Crenarchaeota domains. The bacterial clones exhibited greater overall diversity than the archaeal clones, with sequences related to the Bacteroidetes, Planctomycetes, Actinobacteria, Proteobacteria, and green nonsulfur groups. The majority of the bacterial clones were either members of a novel lineage or most closely related to uncultured clones. The results of these analyses suggest that the microbial community in this environment is distinct from those in previously characterized methane hydrate-bearing sediments. PMID:12147470

  11. Contamination of port zone sediments by metals from Large Marine Ecosystems of Brazil.

    Science.gov (United States)

    Buruaem, Lucas M; Hortellani, Marcos A; Sarkis, Jorge E; Costa-Lotufo, Leticia V; Abessa, Denis M S

    2012-03-01

    Sediment contamination by metals poses risks to coastal ecosystems and is considered to be problematic to dredging operations. In Brazil, there are differences in sedimentology along the Large Marine Ecosystems in relation to the metal distributions. We aimed to assess the extent of Al, Fe, Hg, Cd, Cr, Cu, Ni, Pb and Zn contamination in sediments from port zones in northeast (Mucuripe and Pecém) and southeast (Santos) Brazil through geochemical analyses and sediment quality ratings. The metal concentrations found in these port zones were higher than those observed in the continental shelf or the background values in both regions. In the northeast, metals were associated with carbonate, while in Santos, they were associated with mud. Geochemical analyses showed enrichments in Hg, Cd, Cu, Ni and Zn, and a simple application of international sediment quality guidelines failed to predict their impacts, whereas the use of site-specific values that were derived by geochemical and ecotoxicological approaches seemed to be more appropriate in the management of the dredged sediments. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Influence of enhancing electrolytes on the removal efficiency of heavy metals from Gabes marine sediments (Tunisia).

    Science.gov (United States)

    Missaoui, Amel; Said, Imen; Lafhaj, Zoubeir; Hamdi, Essaieb

    2016-12-15

    This study focused on the feasibility of the treatment of heavy metals-contaminated sediments from Gabes harbor (Tunisia) using enhanced electrokinetic process. It presented a laboratory short-time electrokinetic experiment. The enhancing agents, as citric, acetic acids and sodium dodecyl sulfate (SDS) were used regarding their low environmental hazard. The electrokinetic cell was specially designed in order to elaborate two experiments at the same time. This paper is composed of three parts. The first part introduces the characterization of Gabes sediments. The second part describes the design of laboratory electrokinetic cell and the followed methods. The third part is dedicated to the results analysis. Treatment efficiency revealed that more than 80% of lead was removed from Gabes marine sediments. The reduction of cooper concentration, in sediments after treatment, ranged from 74 to 87%. Despite, the high removal of cadmium that ranged from 58 to 79%, treated sediments presented Cd concentration above the threshold limit. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Recognizing magnetostratigraphy in overprinted and altered marine sediments: Challenges and solutions from IODP Site U1437

    Science.gov (United States)

    Musgrave, Robert J.; Kars, Myriam

    2016-08-01

    Core disturbance, drilling overprints, postdepositional acquisition of remanence, authigenic growth of magnetic iron sulfides, and alteration all contribute challenges to recognizing the primary magnetostratigraphy in marine sediments. We address these issues in a sequence of tuffaceous muds and volcaniclastics at International Ocean Discovery Program Site U1437 and produce the longest continuous magnetic polarity stratigraphy in the history of scientific ocean drilling. Remanence measurements were filtered to remove intervals affected by fluidization, plastic sediment disturbance, and core biscuiting. Drilling overprints are concentrated in the disturbed annulus surrounding intact core material. Bioturbation was limited to a vertical extent of at most 15 cm. Changes in sediment color, stiffness, and magnetic hysteresis all suggest that remanence was locked in within a few meters of the sediment-water interface. We did not observe any systematic offset between magnetostratigraphic and biostratigraphic datums. Authigenic growth of greigite, in response to both initial sulfate reduction in the upper 50 m of the sediment column and to deeper resupply of sulfate, has led to magnetic overprinting. Anomalous polarity artefacts, extending acquired by greigite produced during early diagenesis. Diagenetic magnetic mineral alteration resulted in the progressive loss of fine-grained magnetite, which enhanced susceptibility to drilling and postdrilling overprints and increased the resistance of these overprints to removal by conventional demagnetization. We recovered the magnetostratigraphic record from many samples with resistant overprints through low-temperature demagnetization through the Verwey transition.

  14. Effect of temperature and salinity on phosphate sorption on marine sediments.

    Science.gov (United States)

    Zhang, Jia-Zhong; Huang, Xiao-Lan

    2011-08-15

    Our previous studies on the phosphate sorption on sediments in Florida Bay at 25 °C in salinity 36 seawater revealed that the sorption capacity varies considerably within the bay but can be attributed to the content of sedimentary P and Fe. It is known that both temperature and salinity influence the sorption process and their natural variations are the greatest in estuaries. To provide useful sorption parameters for modeling phosphate cycle in Florida Bay, a systematic study was carried out to quantify the effects of salinity and temperature on phosphate sorption on sediments. For a given sample, the zero equilibrium phosphate concentration and the distribution coefficient were measured over a range of salinity (2-72) and temperature (15-35 °C) conditions. Such a suite of experiments with combinations of different temperature and salinity were performed for 14 selected stations that cover a range of sediment characteristics and geographic locations of the bay. Phosphate sorption was found to increase with increasing temperature or decreasing salinity and their effects depended upon sediment's exchangeable P content. This study provided the first estimate of the phosphate sorption parameters as a function of salinity and temperature in marine sediments. Incorporation of these parameters in water quality models will enable them to predict the effect of increasing freshwater input, as proposed by the Comprehensive Everglades Restoration Plan, on the seasonal cycle of phosphate in Florida Bay.

  15. Effects of terrestrial and marine organic matters on deposition of dechlorane plus (DP) in marine sediments from the Southern Yellow Sea, China: Evidence from multiple biomarkers.

    Science.gov (United States)

    Wang, Guoguang; Peng, Jialin; Hao, Ting; Feng, Lijuan; Liu, Qiaoling; Li, Xianguo

    2017-11-01

    As an emerging halogenated organic contaminant, Dechlorane Plus (DP) was scarcely reported in marine environments, especially in China. In this work, 35 surface sediments and a sediment core were collected across the Southern Yellow Sea (SYS) to comprehensively explore the spatio-temporal distribution and possible migration pathway of DP. DP concentrations ranged from 14.3 to 245.5 pg/g dry weight in the surface sediments, displaying a seaward increasing trend with the high levels in the central mud zone. This spatial distribution pattern was ascribed to that fine particles with the elevated DP levels were preferentially transported to the central mud zone under hydrodynamic forcing and/or via long-range atmospheric transportation and deposition. DP concentrations in sediment core gradually increased from the mid-1950s to present, which corresponded well with the historical production and usage of DP, as well as the economic development in China. Significantly positive correlation between DP and total organic carbon (TOC) in both surface sediments and sediment core indicated TOC-dependent natural deposition of DP in the SYS. We used multiple biomarkers, for the first time, to explore the potential effects of terrestrial and marine organic matters (TOM and MOM) on DP deposition. The results showed that competition may occur between TOM and MOM for DP adsorption, and MOM was the predominant contributor in controlling DP deposition in the marine sediments from the SYS. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Unique actinomycetes from marine caves and coral reef sediments provide novel PKS and NRPS biosynthetic gene clusters.

    Science.gov (United States)

    Hodges, Tyler W; Slattery, Marc; Olson, Julie B

    2012-06-01

    In the ever-expanding search for novel bioactive molecules and enzymes, marine actinomycetes have proven to be a productive source. While open reef sediment and sponge-associated actinomycetes have been extensively examined, their marine cave counterparts remain unevaluated. Anchialine cave systems in the Bahamas offered an ideal setting to evaluate the occurrence and variation within sediment-associated actinomycete communities. While in close geographical proximity to open reef environments, these systems provide a specialized environmental niche devoid of light and direct exposure to nutrient input. In the present study, selective isolation techniques and molecular methods were used to test the hypothesis that variable distribution of actinomycetes and secondary metabolite gene clusters occur between open reef and marine cave systems. The results indicated that differences exist within the culturable sediment-associated actinomycete communities between marine caves and open reef systems, with members of the genus Streptomyces dominating cultures from open reef sediments and a more diverse suite of actinomycetes isolated from marine cave sediment samples. Within the cave isolates, members of the proposed genus Solwaraspora were the most represented. Based on PKS- and NRPS-gene-targeted PCR amplification and sequencing, geographic variation in the occurrence of these biosynthetic pathways was also observed. These findings indicate that marine cave systems are a lucrative source in the search for novel secondary metabolite producers with biotechnological applications and that environmental and geographic factors likely affect the occurrence of these biosynthetic pathways.

  17. 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.

  18. The Link between Microbial Diversity and Nitrogen Cycling in Marine Sediments Is Modulated by Macrofaunal Bioturbation.

    Directory of Open Access Journals (Sweden)

    Maryam Yazdani Foshtomi

    Full Text Available The marine benthic nitrogen cycle is affected by both the presence and activity of macrofauna and the diversity of N-cycling microbes. However, integrated research simultaneously investigating macrofauna, microbes and N-cycling is lacking. We investigated spatio-temporal patterns in microbial community composition and diversity, macrofaunal abundance and their sediment reworking activity, and N-cycling in seven subtidal stations in the Southern North Sea.Our results indicated that bacteria (total and β-AOB showed more spatio-temporal variation than archaea (total and AOA as sedimentation of organic matter and the subsequent changes in the environment had a stronger impact on their community composition and diversity indices in our study area. However, spatio-temporal patterns of total bacterial and β-AOB communities were different and related to the availability of ammonium for the autotrophic β-AOB. Highest bacterial richness and diversity were observed in June at the timing of the phytoplankton bloom deposition, while richness of β-AOB as well as AOA peaked in September. Total archaeal community showed no temporal variation in diversity indices.Distance based linear models revealed that, independent from the effect of grain size and the quality and quantity of sediment organic matter, nitrification and N-mineralization were affected by respectively the diversity of metabolically active β-AOB and AOA, and the total bacteria, near the sediment-water interface. Separate models demonstrated a significant and independent effect of macrofaunal activities on community composition and richness of total bacteria, and diversity indices of metabolically active AOA. Diversity of β-AOB was significantly affected by macrofaunal abundance. Our results support the link between microbial biodiversity and ecosystem functioning in marine sediments, and provided broad correlative support for the hypothesis that this relationship is modulated by macrofaunal

  19. Determination of sediment metal background concentrations and enrichment in marine environments - A critical review.

    Science.gov (United States)

    Birch, G F

    2017-02-15

    'Background' is the concentration of metals in pristine sediment, unaltered by human activity and 'enrichment' is the extent present-day sediment metal concentrations exceed pre-anthropogenic levels (the magnitude of human-induced change). Background and enrichment are becoming more frequently used for management measures to bring sediment and the environment back to near-pristine levels. Of the six empirical methods reviewed for determining background (global values, pristine marine and fluvial sediments, catchment soils and rocks), the use of sedimentary cores has the greatest advantage. Most of the eight statistical methods reviewed are adversely affected by the polymodality and an absence of normality or log-normality, however robust regression procedures are most commonly used. Sorption hypothesis techniques require further development. Indices used to determine enrichment incorporate background levels (enrichment indices) or do not (contamination indices). Of the 20 indices reviewed, the New Nemerow Index and the Mean Enrichment Quotient rate highly in performance, based on 5 beneficial attributes assessed: use of background and normalised data, provision of thresholds, a classification scheme, and inclusion of multiple metals. Variance in background metal concentrations determined in the 43 global projects reviewed is surprisingly moderate, however regional variability may be considerable due to local catchment mineralisation. Chemical analysis of sediment should not include metals bound in the mineral matrix and weak acid extractions are advisable. The use of appropriate and effective indicators of environmental condition are critical to the protection and restoration of marine regions and ensuring that human activities are carried out in a sustainable manner to promote safe, healthy and productive ecosystems. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. 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.

  1. Pleistocene reduction of polar ice caps: Evidence from Cariaco Basin marine sediments

    Science.gov (United States)

    Poore, R.Z.; Dowsett, H.J.

    2001-01-01

    Sea level is projected to rise between 13 and 94 cm over the next 100 yr due to continued climate warming. The sea-level projections assume that polar ice sheets will remain stable or even increase on time scales of centuries, but controversial geologic evidence suggests that current polar ice sheets have been eliminated or greatly reduced during previous Pleistocene interglacials indicating that modern polar ice sheets have become unstable within the natural range of interglacial climates. Sea level may have been more than 20 m higher than today during a presumably very warm interglacial about 400 ka during marine isotope stage 11. Because of the implications for future sea level rise, additional study of the conflicting evidence for warmer conditions and higher sea level during marine isotope stage 11 is needed. Here we present microfossil and isotopic data from marine sediments of the Cariaco Basin supporting the interpretation that global sea level was 10-20 m higher than today during marine isotope stage 11. The increased sea level requires reduction in modern polar ice sheets and is consistent with the interpretation that the West Antarctic ice sheet and the Greenland ice sheet were absent or greatly reduced during marine isotope stage 11. Our results show a warm marine isotope stage 11 interglacial climate with sea level as high as or above modern sea level that lasted for 25 to 30 k.y. Variations in Earth's orbit around the sun (Milankovitch cycles) are considered to be a primary external force driving glacial-interglacial cycles. Current and marine isotope stage 11 Milankovitch forcing are very similar, suggesting that the present interglacial (Holocene) that began ca. 10 ka will continue for another 15 to 20 k.y. Therefore any anthropogenic climate warming will accelerate the natural process toward reduction in polar ice sheets. The potential for increased rates of sea level rise related to polar ice sheet decay should be considered as a potential natural

  2. A budget of marine and terrigenous sediments, Hanalei Bay, Kauai, Hawaiian Islands

    Science.gov (United States)

    Calhoun, R.S.; Fletcher, C.H.; Harney, J.N.

    2002-01-01

    The sediment budget of Hanalei Bay on the north shore of Kauai was calculated using sedimentological and geophysical methods. The calculations of the budget subsequently allowed an interpretation of the Holocene history of the bay. The bay sediments are easily separated into marine (carbonate) and terrigenous (siliciclastic) grains. Surficial sediments are dominated by carbonate grains ( ??? 70%) of coralline algae, coral, and mollusc fragments as well as foraminifera, Halimeda, bryozoa, and echinoderm tests. However, siliciclastic grains (e.g. olivine, plagioclase, volcanic lithics) from the Hanalei River watershed draining shield volcanic highlands are the most common individual grain type ( ??? 27%) and form a zone of high concentration from the mouth of the Hanalei River into the center of the bay. Flooding in the bay by the post-glacial sea-level rise began soon after 11.7 kyears. The resulting marine environment caused the net deposition of 45.5 ?? 1.5 ?? 106 m3 of sediment in the bay and approximately 33.7 ?? 11.2 ?? 106 m3 of sediment on the Hanalei coastal plain. The total volume of carbonate sediment stored in the bay and coastal plain is greater than the volume likely to have been produced exclusively within the bay during the same time. Calculations indicate that approximately 2490 m3 year-1 have been imported into the bay or coastal plain and deposited since 11,700 years ago. The majority of this sediment influx is likely delivered from the east by the strong tradewind-driven littoral currents that characterize Kauai's north shore. Net carbonate sediment deposition in Hanalei Bay peaked at a rate of 15,500 m3 year-1 between 5000 and 3000 years ago (when sea level may have been 2 m above present) diminishing to 3890 m3 year-1 from 1000 years ago to the present. This influx is likely to have played a significant role in the mid to late Holocene progradation of the Hanalei shoreline. ?? 2002 Elsevier Science B.V. All rights reserved.

  3. Effects of Feeding Strategy, Sediment Characteristics, and Chemical Properties on Polychlorinated Biphenyl and Polybrominated Diphenyl Ether Bioaccumulation from Marine Sediments in Two Invertebrates.

    Science.gov (United States)

    Frouin, H; Jackman, P; Dangerfield, N D; Ross, P S

    2017-08-01

    Shellfish and sediment invertebrates have been widely used to assess pollution trends over space and time in coastal environments around the world. However, few studies have compared the bioaccumulation potential of different test species over a range of sediment-contaminant concentrations and profiles. The bioavailability of sediment-related contaminants was evaluated using sediments collected from sites (n = 12) throughout the Salish Sea, British Columbia, Canada. Two benthic marine invertebrates-the Baltic clam Macoma balthica and the polychaete worm Neanthes arenaceodentata-were exposed for 28 days in a controlled environment to these field-collected coastal sediments. The congener-specific uptake of legacy polychlorinated biphenyls (PCBs) and emergent polybrominated diphenyl ethers (PBDEs) was determined using high-resolution gas chromatography/mass spectrometry in sediments and in invertebrates after the experimental exposure. The polychaete Neanthes accumulated lower concentrations of PCBs but higher concentrations of PBDEs. The present study indicates that differences in bioaccumulation between these two invertebrates shape the accumulation of PCB and PBDE congeners, reflect differences in feeding strategies, and reveal the physicochemical properties of the contaminants and sediment properties. Because biota-sediment accumulation factor values are often calculated for environmental monitoring or site-specific impact assessments, our results provide insight into potentially confounding factors and the need for caution when selecting indicator species for coastal marine pollution.

  4. 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.

  5. HEAVY METAL CONTENTS IN MARINE SEDIMENTS AND SEAWATER AT TOTOK BAY AREA, NORTH SULAWESI

    Directory of Open Access Journals (Sweden)

    Delyuzar Ilahude

    2017-07-01

    Full Text Available The study area is located in north-eastern part of Tomini Bay, approximately 80 km south of Manado city, North Sulawesi. This area is closed to submarine tailing disposal system in Buyat Bay. Five marine sediment samples and four water samples from seawater and dig wells have been used for heavy metals (Hg, As, CN analyses by using Atomic Absorption Spectrometry (AAS. This study is a part of research conducted by Marine Geological Institute of Indonesia on morphological changes of seabed in the Totok Bay. The result shows that concentration of mercury (Hg in water samples taken from Ratatotok estuary is higher than standards stipulated Government Regulation (Peraturan Pemerintah/PP No. 82/2001. Meanwhile, concentration of arsenic (As is almost reaching its standard threshold, and conversely cyanide (CN concentration is low. This value of mercury (Hg concentration taken from Ratatotok estuary is much higher than water samples from of Buyat Bay estuary. Significant concentration of mercury (Hg analysed from those particular sampling sites indicated high mercury contamination. Therefore, further examination on ground water of dig wells is necessary, especially for mercury analysis (Hg. Furthermore, comparing the formerly obtained data of mercury concentration in the sediment, this particular study concludes that the sediments in the Totok Bay had contaminated by mercury from gold-processing of illegal mining.

  6. Exploring the diversity and metabolic potential of actinomycetes from temperate marine sediments from Newfoundland, Canada.

    Science.gov (United States)

    Duncan, K R; Haltli, B; Gill, K A; Correa, H; Berrué, F; Kerr, R G

    2015-01-01

    Marine sediments from Newfoundland, Canada were explored for biotechnologically promising Actinobacteria using culture-independent and culture-dependent approaches. Culture-independent pyrosequencing analyses uncovered significant actinobacterial diversity (H'-2.45 to 3.76), although the taxonomic diversity of biotechnologically important actinomycetes could not be fully elucidated due to limited sampling depth. Assessment of culturable actinomycete diversity resulted in the isolation of 360 actinomycetes representing 59 operational taxonomic units, the majority of which (94 %) were Streptomyces. The biotechnological potential of actinomycetes from NL sediments was assessed by bioactivity and metabolomics-based screening of 32 representative isolates. Bioactivity was exhibited by 41 % of isolates, while 11 % exhibited unique chemical signatures in metabolomics screening. Chemical analysis of two isolates resulted in the isolation of the cytotoxic metabolite 1-isopentadecanoyl-3β-D-glucopyranosyl-X-glycerol from Actinoalloteichus sp. 2L868 and sungsanpin from Streptomyces sp. 8LB7. These results demonstrate the potential for the discovery of novel bioactive metabolites from actinomycetes isolated from Atlantic Canadian marine sediments.

  7. 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.

  8. Shear-wave velocity of marine sediments offshore Taiwan using ambient seismic noise

    Science.gov (United States)

    Lin, Yu-Tse; Lin, Jing-Yi; Kuo-Chen, Hao; Yeh, Yi-Chin; Cheng, Win-Bin

    2017-04-01

    Seismic ambient noise technology has many advantages over the traditional two-station method. The most important one is that noise is happening all the time and it can be widely and evenly distributed. Thus, the Green's Function of any station pair can be obtained through the data cross-correlation process. Many related studies have been performed to estimate the velocity structures based on the inland area. Only a few studies were reported for the marine area due to the relatively shorter recording time of ocean bottom seismometers (OBS) deployment and the high cost of the marine experiment. However, the understanding about the shear-wave velocity (Vs) of the marine sediments is very crucial for the hazard assessment related to submarine landslides, particularly with the growing of submarine resources exploration. In this study, we applied the ambient noise technique to four OBS seismic networks located offshore Taiwan in the aim of getting more information about the noise sources and having the preliminary estimation for the Vs of the marine sediments. Two of the seismic networks were deployed in the NE part of Taiwan, near the Ryukyu subduction system, whereas the others were in the SW area, on the continental margin rich in gas hydrate. Generally, ambient seismic noise could be associated with wind, ocean waves, rock fracturing and anthropogenic activity. In the southwestern Taiwan, the cross-correlation function obtained from two seismic networks indicate similar direction, suggestion that the source from the south part of the network could be the origin of the noise. However, the two networks in the northeastern Taiwan show various source direction, which could be caused by the abrupt change of bathymetry or the volcanic degassing effect frequently observed by the marine geophysical method in the area. The Vs determined from the dispersion curve shows a relatively higher value for the networks in the Okinawa Trough (OT) off NE Taiwan than that in the

  9. Experimental Constraints on Microbial Liberation of Structural Iron from Common Clay Minerals in Marine Sediments

    Science.gov (United States)

    Metcalfe, K. S.; Gaines, R. R.; Trang, J.; Scott, S. W.; Crane, E. J.; Lackey, J.; Prokopenko, M. G.; Berelson, W.

    2013-12-01

    Iron is a limiting nutrient in many marine settings. The marine Fe-cycle is complex because Fe may be used as an electron donor or acceptor and cycled many times before ultimate burial in sediments. Thus, the availability of iron plays a large role in the marine carbon cycle, influencing not only the extent of primary productivity but also the oxidation of organic matter in sediments. The primary constituents of marine sediments are clay minerals, which commonly contain lattice-bound Fe in octahedral sites. In marine settings, the pool of Fe bound within silicate mineral lattices has long been considered reactive only over long timescales, and thus non-bioavailable. In vitro experimental evidence has shown that lab cultures of Fe-reducing bacteria are able to utilize structurally-bound Fe (III) from the crystal lattice of nontronite, an uncommon but particularly Fe-rich (> 12 wt.%) smectite. Importantly, this process is capable of liberating Fe (II) to solution, where it is available to biotic processes as an electron donor. In order to constrain the capacity of naturally-occurring marine bacteria to liberate structurally-coordinated Fe from the lattices of common clay minerals, we exposed a suite of 16 different clay minerals (0.8-13.9 wt.% Fe) to lab cultures of known Fe-reducer S. onenidensis MR-1 and to a natural consortium of Fe-reducing microbes from the San Pedro and Santa Monica Basins over timescales ranging from 7-120 days. Clay minerals were treated with Na-dithionite to extract surface-bound Fe prior to exposure. Crystallographic data and direct measurements of Fe in solution demonstrate the release of structural Fe from all clay minerals analyzed. Neoformation of illite and amorphous quartz were observed. The array of clay minerals and microbes used in this experiment complement past findings and suggest that common clay minerals may represent a large and previously unrecognized pool of bioavailable Fe in the world ocean that contributes significantly

  10. Toxicity assessment in marine sediment for the Terra Nova environmental effects monitoring program (1997-2010)

    Science.gov (United States)

    Whiteway, Sandra A.; Paine, Michael D.; Wells, Trudy A.; DeBlois, Elisabeth M.; Kilgour, Bruce W.; Tracy, Ellen; Crowley, Roger D.; Williams, Urban P.; Janes, G. Gregory

    2014-12-01

    This paper discusses toxicity test results on sediments from the Terra Nova offshore oil development. The Terra Nova Field is located on the Grand Banks approximately 350 km southeast of Newfoundland (Canada). The amphipod (Rhepoxynius abronius) survival and solid phase luminescent bacteria (Vibrio fischeri, or Microtox) assays were conducted on sediment samples collected from approximately 50 stations per program year around Terra Nova during baseline (1997), prior to drilling, and in 2000, 2001, 2002, 2004, 2006, 2008 and 2010 after drilling began. The frequency of toxic responses in the amphipod toxicity test was low. Of the ten stations that were toxic in environmental effects monitoring (EEM) years, only one (station 30(FE)) was toxic in more than one year and could be directly attributed to Terra Nova project activities. In contrast, 65 (18%) of 364 EEM samples were toxic to Microtox. Microtox toxicity in EEM years was not related to distance from Terra Nova drill centres or concentrations of >C10-C21 hydrocarbons or barium, the primary constituents of the synthetic-based drill muds used at Terra Nova. Of the variables tested, fines and strontium levels showed the strongest (positive) correlations with toxicity. Neither fines nor strontium levels were affected by drill cuttings discharge at Terra Nova, except at station 30(FE) (and that station was not toxic to Microtox). Benthic macro-invertebrate abundance, richness and diversity were greater in toxic than in non-toxic sediments. Therefore, Microtox responses indicating toxicity were associated with positive biological responses in the field. This result may have been an indirect function of the increased abundance of most invertebrate taxa in less sandy sediments with higher gravel content, where fines and strontium levels and, consequently, toxicity to Microtox were high; or chemical substances released by biodegradation of organic matter, where invertebrates are abundant, may be toxic to Microtox. Given

  11. 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

  12. EVALUATION OF A FIRST-ORDER MODEL FOR THE PREDICTION OF THE BIOACCUMULATION OF PCBS AND DDT FROM SEDIMENT INTO THE MARINE DEPOSIT-FEEDING CLAM MACOMA NASUTA

    Science.gov (United States)

    A first-order model for predicting contaminant bioaccumulation from sediments into benthic invertebrates was validated using a marine deposit-feeding clam, Macoma nasuta, exposed to polychlorobiphenyl (PCB)-spiked and dichlorodiphenyltrichloroethane (DDT)-contaminated sediments. ...

  13. Constraining the global inventory of methane hydrates in marine sediments (Invited)

    Science.gov (United States)

    Wallmann, K. J.; Burwiczi, E.; Rupke, L.; Marquardt, M.; Pinero, E.; Haeckel, M.; Hensen, C.

    2010-12-01

    Recent estimates for the global inventory of methane carbon bound in marine gas hydrates vary over several orders of magnitude from ~500 Gt C to more than 70,000 Gt C. These estimates are based on field observations or diagenetic models simulating the microbial degradation of organic matter within the hydrate stability zone under Holocene boundary conditions. Here, we present new global estimates applying an enhanced transport-reaction model for microbial methane production and hydrate formation in marine sediments. The kinetic model considers the down-core decrease in reactivity of organic matter and the inhibition of methane production via accumulation of metabolites in sediment pore fluids. The model was successfully tested at a significant number of ODP drill sites and model parameters were constrained considering the down-core decrease in dissolved sulfate and the accumulation of dissolved metabolites in pore fluids (ammonium, alkalinity, methane, etc.). The calibrated model was subsequently applied on a global grid considering available data sets on particulate organic carbon (POC) concentrations in surface sediments, Holocene sedimentation rates, and the thickness of the gas hydrate stability zone (GHSZ). This modeling exercise showed that only 0 - 4 Gt of methane carbon would accumulate in gas hydrates via microbial methane formation within the GHSZ. Additional model runs under Holocene boundary conditions showed that significant amounts of gas hydrate are only formed via upward gas and fluid flow. However, the erosion of continental shelf sediments during glacial sea-level low-stands and the re-deposition of sediments at the continental slope and rise may increase the POC input to the GHSZ and the accumulation of gas hydrates during glacial periods. A global inventory of up to ~1000 Gt C was calculated for average Quaternary boundary conditions assuming that the particle load of rivers is ultimately deposited at the continental slope and rise. The model

  14. Accumulation of copper, zinc, cadmium and lead from two contaminated sediments by three marine invertebrates: a laboratory study

    Energy Technology Data Exchange (ETDEWEB)

    Ray, S.; McLeese, D.W.; Peterson, M.R.

    1981-03-01

    Animals from areas with contaminated sediments have been shown in some cases to contain high levels of trace metals. In other cases, the tissue levels of contaminants were relatively constant regardless of the metal contents of the sediments. The availability of sediment-bound metals to bottom-dwelling organisms has been the subject of a few studies. This study describes the uptake of copper, zinc, cadmium and lead from natural, highly contaminated sediments by three marine invertebrates: Nereis virens, Macoma balthica and Crangon septemspinosa.

  15. Are Sediments a Source of Fukushima Radiocesium for Marine Fauna in Coastal Japan?

    Science.gov (United States)

    Wang, C.; Fisher, N. S.; Baumann, Z.

    2016-02-01

    The Fukushima nuclear power plant accident in 2011 resulted in the largest accidental release of artificial radionuclides into the world's oceans. Among the fission products released in large quantities, 137Cs has the greatest potential for long-term impacts on marine biota and human consumers of seafood. In particular, some species of bottom fish near Fukushima were very contaminated and had higher radiocesium (134Cs and 137Cs) levels than pelagic fish in the same area, sometimes exceeding Japanese safety limits >4 years after the accident. Benthic invertebrates, many being prey items for bottom fish, show the same slow decrease in radiocesium as sediments, suggesting that contaminated sediment could be a source of radiocesium for benthic fauna. We evaluated the binding of 137Cs to sediments (Kd found to be 44-60 ml g-1) and found that bioturbation by the polychaete Nereis succinea greatly increased the initial release rate of Cs to overlying seawater. We also assessed the bioavailability of dissolved and sediment-bound Cs for deposit-feeding polychaetes, and its subsequent transfer to crabs and fish, and measured the influence of water temperature on Cs accumulation in fish. Assimilation efficiency (AE) of ingested 137Cs ranged from 16% in polychaetes ingesting sediments to 79% in fish ingesting worms. Efflux rate constants ranged from 5% d-1 for killifish to 40% d-1 for polychaetes. Animal absorption and retention of dissolved 137Cs were also measured. These parameters are used to model radiocesium bioaccumulation and trophic transfer in benthic food chains. Our results are consistent with the idea that sediments can be an important source of Cs for benthic food chains and help explain why some species of bottom fish remained more contaminated than pelagic fish in Japanese coastal waters.

  16. Microplastic pollution in the marine waters and sediments of Hong Kong.

    Science.gov (United States)

    Tsang, Y Y; Mak, C W; Liebich, C; Lam, S W; Sze, E T-P; Chan, K M

    2017-02-15

    The presence of plastic waste with a diameter of less than 5mm ("microplastics") in marine environments has prompted increasing concern in recent years, both locally and globally. We conducted seasonal surveys of microplastic pollution in the surface waters and sediments from Deep Bay, Tolo Harbor, Tsing Yi, and Victoria Harbor in Hong Kong between June 2015 and March 2016. The average concentrations of microplastics in local coastal waters and sediments respectively ranged from 51 to 27,909particles per 100m(3) and 49 to 279particles per kilogram. Microplastics of different shapes (mainly fragments, lines, fibers, and pellets) were identified as polypropylene, low-density polyethylene, high-density polyethylene, a blend of polypropylene and ethylene propylene, and styrene acrylonitrile by means of Attenuated Total Reflectance - Fourier Transform Infrared Spectroscopy. This is the first comprehensive study to assess the spatial and temporal variations of microplastic pollution in Hong Kong coastal regions. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    1987-01-01

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

  18. MATHEMATICAL MODELING OF THE ELECTRIC CURRENT GENERATION IN A MICROBIAL FUEL CELL INOCULATED WITH MARINE SEDIMENT

    Directory of Open Access Journals (Sweden)

    J. T. Teleken

    Full Text Available Abstract Microbial fuel cells (MFC are electrochemical devices that utilize the ability of some microorganisms to oxidize organic matter and transfer electrons resulting from their metabolism to an insoluble acceptor. The goal of the present study was to model the kinetics of electrical current generation from an MFC inoculated with marine sediment. For this purpose, a differential equation system was used, including the Nernst-Monod relationship and Ohm's Law, to describe the microbial metabolism and the mechanism of extracellular electron transfer (EET, respectively. The experimental data obtained by cyclic voltammetry analysis were properly described by the model. It was concluded that marine microorganisms preferably use a direct mechanism of EET by means of nanowires to establish the electrochemical contact with the anode. The mathematical modeling could help understand MFC operation and, consequently, contribute to improving power generation from this source.

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

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Chul-Hwan [School of Earth and Environmental Sciences (Oceanography), College of Natural Sciences, Seoul National University, Seoul 151-742 (Korea, Republic of); Khim, Jong Seong [School of Earth and Environmental Sciences (Oceanography), College of Natural Sciences, Seoul National University, Seoul 151-742 (Korea, Republic of)]. E-mail: jskocean@snu.ac.kr; Villeneuve, Daniel L. [U.S. Environmental Protection Agency, Mid-Continent Ecology Division, 6201 Congdon Blvd., Duluth, MN 55804-2595 (United States); Kannan, Kurunthachalam [Wadsworth Center, New York State Department of Health and Department of Environmental Health and Toxicology, State University of New York at Albany, Empire State Plaza, PO Box 509, Albany, NY 12201-0509 (United States); Giesy, John P. [National Food Safety and Toxicology Center, Department of Zoology, and Institute for Environmental Toxicology, Michigan State University, East Lansing, MI 48824 (United States); Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2006-07-15

    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.

  20. 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.

  1. Investigating Dechlorane Plus (DP) distribution and isomer specific adsorption behavior in size fractionated marine sediments.

    Science.gov (United States)

    Fang, Mingliang; Kim, Jong-Chul; Chang, Yoon-Seok

    2014-05-15

    In this study, Dechlorane Plus (DP) concentrations were analyzed in marine sediments (depth: ~10 cm) from two Korean industrial bays. Two sediments were fractionated into 5 sizes by using gravitational split-flow thin fractionation technique and DP distribution was investigated in different particle size fractions. Elevated DP levels in surface sediments were observed at the site closest to land and industrial area. The highest concentrations of DP were detected in the finest grain-size (adsorption of anti-DP or higher biodegradation rates of syn-DP in the fine particles. To provide insight into such mechanism, simulated experiments were conducted using activated charcarbon (ACC) to adsorb DP dissolved in methanol and molecular descriptors of both isomers were estimated using Gaussian 03. The adsorption results revealed that syn-DP was preferentially adsorbed by ACC, suggesting syn-DP is more hydrophobic than anti-DP. The preferential adsorption of syn-DP by ACC also supported the hypothesis that the enrichment of anti-DP was more likely due to preferential biodegradation of syn-DP in the sediment. Molecular characterization of anti-DP and syn-DP showed that syn-DP had a higher dipole moment, slightly larger Van der Waals volume, but smaller maximal diameter, which might explain its higher uptake rate in biota. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

  2. Competitive adsorption of phthalate esters on marine surface sediments: kinetic, thermodynamic, and environmental considerations.

    Science.gov (United States)

    Mohammadian, Somaye; Ghanemi, Kamal; Nikpour, Yadollah

    2016-12-01

    In this study, the sorption behavior of six widely used phthalate esters (PEs) on marine sediments was investigated. The adsorption of PEs was fast and reached the equilibrium within 6 h. The forward and backward rate constants of all PEs on sediments were calculated. Several kinds of kinetic and thermodynamic models have been investigated; the pseudo-second-order model and the partition isotherm model were best fitted to the adsorption behavior of PEs. The rate-limiting step of sorption was controlled by the film diffusion mechanism. After treating sediments with H2O2, the partition coefficients of all PEs were significantly reduced and indicated that the amorphous organic carbon has a major role in adsorption process. The negative values of ΔH° and ΔG° for these compounds showed that the sorption process is exothermic and spontaneous. The adsorption capacities of all PEs were slightly influenced by increasing the salinity from 0 to 40 g L-1. These research findings have a prime importance on assessment of the fate and transport of PEs in seawater-sediment systems.

  3. Diffuser Design For Marine Outfalls in Areas With Strong Currents, High Waves and Sediment Transport

    DEFF Research Database (Denmark)

    Larsen, Torben

    1995-01-01

    The design of marine outfalls are often based on environmental criteria for a minimum initial dilution. Accordingly diffuser arrangement are designed to fulfil these requirements. A large number of examples of malfunction and blocking in sea outfalls have occurred around the world as a result...... of this uncompromising accept of environmental demands. Two examples of unconventional design are given in the paper. Both cases involved risk of blockage of the diffuser section because of wave and current induced sediment transport. The paper also discusses how acceptable far field dilution conditions can be achieved...

  4. Draft genome sequence of a denitrifying bacterium Paracoccus marcusii PAMC 22219 isolated from Arctic marine sediment.

    Science.gov (United States)

    Cha, In-Tae; Song, Eun-Ji; Seok, Yoon Ji; Lee, Hyunjin; Park, Inhye; Lee, Yoo Kyung; Roh, Seong Woon; Choi, Hak-Jong; Nam, Young-Do; Seo, Myung-Ji

    2015-06-01

    A denitrifying bacterium, Paracoccus marcusii PAMC 22219, was isolated from Arctic marine sediment in Svalbard, Norway. The obtained contigs were 265 with genome size of 4.0Mb and G+C content of 66.1%. This bacterial genome revealed that it had nitrate and nitrite ammonification genes involved in the denitrification process, suggesting that P. marcusii PAMC 22219 is a denitrifying bacterium. This is the first genome that has been sequenced in the genus Paracoccus, isolated from an Arctic environment. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. 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.

  6. Stabilization / solidification of polluted marine dredged sediment of port en Bessin France, using hydraulic binders and silica fume

    Science.gov (United States)

    Silitonga, Ernesto

    2017-09-01

    A large amount of sediment is dredged in France every year. Due to the increase of the amount of marine dredged sediments, environmentally reuse of dredged sediment is urgently needed in France. The first objective of this study is to find an application for reuse of marine dredged sediments materials, as new material for road construction. Hence, serial tests need to be realized to identify if marine dredged sediment could be utilized for road construction. The second goal is to enhance the physical, mechanical and chemical characteristics of the mix, by incorporating binders and sediments, and revealed the identification of the mechanical characteristics measured on the mixes is compatible with their use as a base course material. The results show that the treatment by hydraulics binders could satisfy the needed mechanical characteristics. The present of Silica Fume is aimed to reduce the pollution level, especially the heavy metal content. However, the proportion of hydraulics binders and silica fume needed to meet prescribed specification is important, so the reuse of the marine dredged sediments of Port-en-Bessin, France in road construction, as an alternative material could be achieved. After the geotechnical study in laboratory results shown as expected than the study to identify the chemical characteristic realized. To evaluate the environmental impacts of the used material, leaching test is performed. The leaching test was performed to verify the predicted release of pollutants based on total dissolution. And for the final part, the test results show that the polluted marine dredged sediments could be safely used (in term of environmental impact) as a new material in road construction.

  7. 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.

  8. Biogeochemical Insights into B-Vitamins in the Coastal Marine Sediments of San Pedro Basin, CA

    Science.gov (United States)

    Monteverde, D.; Berelson, W.; Baronas, J. J.; Sanudo-Wilhelmy, S. A.

    2015-12-01

    Coastal marine sediments support a high abundance of mircoorganisms which play key roles in the cycling of nutrients, trace metals, and carbon, yet little is known about many of the cofactors essential for their growth, such as the B-vitamins. The suite of B-vitamins (B1, B2, B6, B7, B12) are essential across all domains of life for both primary and secondary metabolism. Therefore, studying sediment concentrations of B-vitamins can provide a biochemical link between microbial processes and sediment geochemistry. Here we present B-vitamin pore water concentrations from suboxic sediment cores collected in September 2014 from San Pedro Basin, a silled, low oxygen, ~900 m deep coastal basin in the California Borderlands. We compare the B-vitamin concentrations (measured via LCMS) to a set of geochemical profiles including dissolved Fe (65-160 μM), dissolved Mn (30-300 nM), TCO2, solid phase organic carbon, and δ13C. Our results show high concentrations (0.8-3nM) of biotin (B7), commonly used for CO2 fixation as a cofactor in carboxylase enzymes. Thiamin (B1) concentrations were elevated (20-700nM), consistent with previous pore water measurements showing sediments could be a source of B1 to the ocean. Cobalamin (B12), a cofactor required for methyl transfers in methanogens, was also detected in pore waters (~4-40pM). The flavins (riboflavin [B2] and flavin mononucleotide[FMN]), molecules utilized in external electron transfer, showed a distinct increase with depth (10-90nM). Interestingly, the flavin profiles showed an inverse trend to dissolved Fe (Fe decreases with depth) providing a potential link to culture experiments which have shown extracellular flavin release to be a common trait in some metal reducers. As some of the first B-vitamin measurements made in marine sediments, these results illustrate the complex interaction between the microbial community and surrounding geochemical environment and provide exciting avenues for future research.

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

    Science.gov (United States)

    Alawi, M.; Kallmeyer, J.

    2012-12-01

    Extracellular DNA (eDNA) is a ubiquitous biological compound in aquatic sediment and soil. Despite major methodological advances, analysis of DNA from sediment is still technically challenging, not just because of the co-elution of inhibitory substances, but also due to co-elution of extracellular DNA, which potentially leads to an overestimate of the actual diversity. Previous studies suggested that eDNA might play an important role in biogeochemical element cycling, horizontal gene transfer and stabilization of biofilm structures. Several protocols based on the precipitation of eDNA e.g. with CTAB and ethanol have already been published. However, using these methods we did not succeed in quantifying very low amounts of eDNA (e.g. applications like PCR can be performed. To evaluate the new extraction method two sediments with rather 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

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

    Science.gov (United States)

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

    2013-11-01

    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 and Janssand). The vertical distribution of DEN activity was examined using the acetylene inhibition technique combined with N2O microsensor measurements, whereas NH4+ production via DNRA was measured with a recently developed gel probe-stable isotope technique. At all field sites, dissimilatory nitrate 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 was detected accounting for 37-77% of the total NO3- reduced. These contradictory results might be explained by enhanced NO3- availability for DNRA bacteria in the sediment slurries compared to the core-incubated sediments in which diffusion of NO3- from the water column may only reach DEN bacteria, but not DNRA bacteria. The true partitioning of dissimilatory nitrate reduction between DNRA and DEN may thus lie in between the values found in whole core (underestimation of DNRA) and slurry incubations (overestimation of DNRA).

  11. Paleo- and environmental magnetic record of Holocene marine sediments from West Greenland

    Science.gov (United States)

    Hatfield, R. G.; Stoner, J. S.; Jennings, A. E.

    2013-12-01

    High resolution records of paleosecular variation (PSV) and relative paleointensity (RPI) are useful relative dating tools and provide opportunities to understand patterns in the apparently stochastic behavior of the earth's geodynamo. The quality of these records is dependent upon sedimentological and environmental conditions that permit the complex, and still poorly understood, sediment magnetic acquisition process; changes to these conditions potentially impacts the fidelity of these records and our interpretation of the paleogeomagnetic field. To understand the potential influence of these effects we measured the paleo- and environmental-magnetic properties of a 12kyr marine record from Disko Bugt, West Greenland which experiences large sedimentological changes related to deglaciation and retreat of the Greenland ice sheet. Proximity of the ice margin to the core site during the early Holocene provided abundant terrigenous fine-grained sediment, resulting in high sedimentation rate, high magnetic susceptibility (MS) and coercivity typical of PSD size magnetite. Maximum angular deviation (MAD) values <1° indicate that the paleomagnetic record is well defined, and PSV and RPI records agree well with well-established regional analogues (e.g. MD99-2269 and MD99-2322) and field models (e.g. CALS10k). Ice-sheet retreat during the mid-late Holocene reduced the flux of terrigenous sediment resulting in lower values of MS and coercivity and consistently higher MAD values (ranging from 2-14°) indicating possible sediment source changes and a less well defined paleomagnetic record. While both PSV and RPI are affected by environmental changes the PSV record appears more resilient, maintaining relatively strong coherence to regional analogues, whereas the RPI record becomes less well defined. These results highlight the dependence of the paleomagnetic record on the environmental regime in which it was deposited, the sensitivity of PSV, and particularly RPI to these

  12. 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)

  13. Diversity and bioprospecting of culturable actinomycetes from marine sediment of the Yellow Sea, China.

    Science.gov (United States)

    Xiong, Zhi-Qiang; Liu, Qiao-Xia; Pan, Zhao-Long; Zhao, Na; Feng, Zhi-Xiang; Wang, Yong

    2015-03-01

    Marine actinomycetes are a potential source of a wide variety of bioactive natural products. In this work, seven pretreatments, three selective isolation media, and five artificial seawater concentrations were used to isolate actinomycetes from the sediments collected from Yellow Sea, China. Statistical analysis showed that only the isolation medium strongly affected the total and bioactive numbers of actinomycete isolates. A total of 613 actinobacterial strains were isolated and screened for antimicrobial activities; 154 isolates showed activity against at least one of nine test drug-resistant microorganisms. Eighty-nine representatives with strong antimicrobial activity were identified phylogenetically based on 16S rRNA gene sequencing, which were assigned to five different actinomycete genera Streptomyces, Kocuria, Saccharomonospora, Micromonospora, and Nocardiopsis. Using PCR-based screening for six biosynthetic genes of secondary metabolites, all 45 isolates with acute activity have at least one biosynthetic gene, 28.8 % of which possess more than three biosynthetic genes. As a case, strain SMA-1 was selected for antimicrobial natural product discovery. Three diketopiperazine dimers including a new compound iso-naseseazine B (1) and two known compounds naseseazine B (2) and aspergilazine A (3) were isolated by bioassay-guided separation. These results suggested that actinomycetes from marine sediments are a potential resource of novel secondary metabolites and drugs.

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

    Directory of Open Access Journals (Sweden)

    Ulrike eJaekel

    2015-02-01

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

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

    Science.gov (United States)

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

    2014-08-01

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

  16. Ecotoxicological evaluation of harbour sediments using marine organisms from different trophic levels

    Energy Technology Data Exchange (ETDEWEB)

    Pane, L.; Giacco, E.; Mariottini, G.L. [Genova Univ. (Italy). Dept. of Biology; Corra, C.; Greco, G.; Faimali, M. [CNR - ISMAR-Marine Technology Section, Genova (Italy); Varisco, F. [Multiproject S.r.l., Gorizia (Italy)

    2008-04-15

    ) of whole sediment placed on multi-well plate bottoms. All end-points were evaluated after 96 h. Results. In general, the effects increased with the increasing of elutriate concentration up to 50%; the stimulation or inhibition of algal growth was statistically significant in comparison to the control. The inhibiting elutriates induced EC{sub 50} variations of algal growth ranging from 66.9% to 74.3%. The mortality of T. fulvus nauplii was always < 25% after treatment with 100% elutriates and < 10% after treatment with 50% dilution; no effect was shown up with 25% dilution; therefore LC{sub 50} was not calculable. The effect of elutriates was negligible on adult copepods and LC{sub 50} values were never calculable; percent mortality always resulted in < 10% after treatment with whole sediments. Discussion. Both experimental systems gave substantially similar results after exposition to whole sediments and elutriates. During the experiment with algal cells, the immobilization in Na-alginate and the employment of inserts which allowed the contact of organisms with sediments and their easy counting were particularly useful. Likewise, the employment of inserts of adequate mesh size in the tests with copepods allowed the contact of organisms with the sediment and made organism handling and counting easy, as well as the evaluation of mortality. The methodology here described and the utilization of the proposed test-species could have an importance also considering that the current trend in ecotoxicological research is towards finding the most appropriate organism for specific areas of concern by using indigenous species (Mariani et al. 2006) and towards the major significance of chronic and reproductive end-points. Conclusions. Based on the above results, it can be stated that the bioassay with Dunaliella tertiolecta could be a good estimation tool for the ecotoxicological assessment of marine sediments. The immobilization of algae in Na-alginate was seen to be useful to

  17. Estimates of Biogenic Methane Production Rates in Deep Marine Sediments at Hydrate Ridge, Cascadia Margin ▿ †

    Science.gov (United States)

    Colwell, F. S.; Boyd, S.; Delwiche, M. E.; Reed, D. W.; Phelps, T. J.; Newby, D. T.

    2008-01-01

    Methane hydrate found in marine sediments is thought to contain gigaton quantities of methane and is considered an important potential fuel source and climate-forcing agent. Much of the methane in hydrates is biogenic, so models that predict the presence and distribution of hydrates require accurate rates of in situ methanogenesis. We estimated the in situ methanogenesis rates in Hydrate Ridge (HR) sediments by coupling experimentally derived minimal rates of methanogenesis to methanogen biomass determinations for discrete locations in the sediment column. When starved in a biomass recycle reactor, Methanoculleus submarinus produced ca. 0.017 fmol methane/cell/day. Quantitative PCR (QPCR) directed at the methyl coenzyme M reductase subunit A gene (mcrA) indicated that 75% of the HR sediments analyzed contained methane produced/g sediment/day for the samples with fewer methanogens than the QPCR method could detect. The actual rates could vary depending on the real number of methanogens and various seafloor parameters that influence microbial activity. However, our calculated rate is lower than rates previously reported for such sediments and close to the rate derived using geochemical modeling of the sediments. These data will help to improve models that predict microbial gas generation in marine sediments and determine the potential influence of this source of methane on the global carbon cycle. PMID:18344348

  18. Integrative assessment of marine pollution in Galician estuaries using sediment chemistry, mussel bioaccumulation, and embryo-larval toxicity bioassays.

    Science.gov (United States)

    Beiras, R; Fernández, N; Bellas, J; Besada, V; González-Quijano, A; Nunes, T

    2003-08-01

    An integrative assessment of environmental quality was carried out in selected sites along the Galician coast (NW Iberian Peninsula) combining analytical chemistry of seawater and sediments, bioaccumulation in the marine mussel, and embryo-larval sediment toxicity bioassays, in order to link biological and chemical criteria for the assessment of coastal pollution. Maximum values of Hg and Cu in seawater, sediment and mussels, were found in the inner part of Ria of Pontevedra, while maximum levels of organics (polychlorinated biphenyls, hexachlorobenzene and aldrin) were found in mussels from A Coruña. Outstanding values of Cu, Pb and Zn have been found in seawater and sediment from a single site, P3, which also was the most toxic in the embryo-larval bioassays performed with four different phyla of marine organisms: mollusks, echinoderms, arthropods and chordates. Sediment quality effects range-median values provided a valuable reference to predict biological effects from sediment chemistry data, while effects range-low values were too conservative. Sediment toxicity could also be predicted by using a toxic-unit model based on published EC50 values for trace metals and mobilization factors independently obtained from measurements of metal contents in sediments and their elutriates. When chemical and toxicological data are independently used to arrange sampling sites by using non-metric multidimensional scaling, a remarkable degree of concordance between both types of configurations could be observed.

  19. Temperature and the sulfur cycle control monomethylmercury cycling in high Arctic coastal marine sediments from Allen Bay, Nunavut, Canada.

    Science.gov (United States)

    St Pierre, K A; Chétélat, J; Yumvihoze, E; Poulain, A J

    2014-01-01

    Monomethylmercury (MMHg) is a neurotoxin of concern in the Canadian Arctic due to its tendency to bioaccumulate and the importance of fish and wildlife in the Inuit diet. In lakes and wetlands, microbial sediment communities are integral to the cycling of MMHg; however, the role of Arctic marine sediments is poorly understood. With projected warming, the effect of temperature on the production and degradation of MMHg in Arctic environments also remains unclear. We examined MMHg dynamics across a temperature gradient (4, 12, 24 °C) in marine sediments collected in Allen Bay, Nunavut. Slurries were spiked with stable mercury isotopes and amended with specific microbial stimulants and inhibitors, and subsampled over 12 days. Maximal methylation and demethylation potentials were low, ranging from below detection to 1.13 pmol g(-1) h(-1) and 0.02 pmol g(-1) h(-1), respectively, suggesting that sediments are likely not an important source of MMHg to overlying water. Our results suggest that warming may result in an increase in Hg methylation - controlled by temperature-dependent sulfate reduction, without a compensatory increase in demethylation. This study highlights the need for further research into the role of high Arctic marine sediments and climate on the Arctic marine MMHg budget.

  20. Modelling the morphology of sandy spits

    DEFF Research Database (Denmark)

    Pedersen, Dorthe; Deigaard, Rolf; Fredsøe, Jørgen

    2008-01-01

    The shape, dimensions and growth rate of an accumulating sandy spit is investigated by a theoretical and experimental study. The idealised case of a spit growing without change of form under a constant wave forcing is considered. The longshore wave-driven sediment transport is taken to be dominan...

  1. Species sensitivity distributions for suspended clays, sediment burial, and grain size change in the marine environment.

    Science.gov (United States)

    Smit, Mathijs G D; Holthaus, Karlijn I E; Trannum, Hilde C; Neff, Jerry M; Kjeilen-Eilertsen, Grete; Jak, Robbert G; Singsaas, Ivar; Huijbregts, Mark A J; Hendriks, A Jan

    2008-04-01

    Assessment of the environmental risk of discharges, containing both chemicals and suspended solids (e.g., drilling discharges to the marine environment), requires an evaluation of the effects of both toxic and nontoxic pollutants. To date, a structured evaluation scheme that can be used for prognostic risk assessments for nontoxic stress is lacking. In the present study we challenge this lack of information by the development of marine species sensitivity distributions (SSDs) for three nontoxic stressors: suspended clays, burial by sediment, and change in sediment grain size. Through a literature study, effect levels were obtained for suspended clays, as well as for burial of biota. Information on the species preference range for median grain size was used to assess the sensitivity of marine species to changes in grain size. The 50% hazardous concentrations (HC50) for suspended barite and bentonite based on 50% effect concentrations (EC50s) were 3,010 and 1,830 mg/L, respectively. For burial the 50% hazardous level (HL50) was 5.4 cm. For change in median grain size, two SSDs were constructed; one for reducing and one for increasing the median grain size. The HL50 for reducing the median grain size was 17.8 mum. For increasing the median grain size this value was 305 mum. The SSDs have been constructed by using information related to offshore oil- and gas-related activities. Nevertheless, the results of the present study may have broader implications. The hypothesis of the present study is that the SSD methodology developed for the evaluation of toxic stress can also be applied to evaluate nontoxic stressors, facilitating the incorporation of nontoxic stressors in prognostic risk assessment tools.

  2. 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

  3. Culturable diversity and antimicrobial activity of Actinobacteria from marine sediments in Valparaíso bay, Chile

    OpenAIRE

    Fernanda Paz Claverías; Agustina Natalia Undabarrena; Myriam eGonzález; Michael eSeeger; Beatriz Patricia Cámara

    2015-01-01

    Marine-derived Actinobacteria are a source of a broad variety of secondary metabolites with diverse biological activities, such as antibiotics and antitumorals; many of which have been developed for clinical use. Rare Actinobacteria represent an untapped source of new bioactive compounds that have been scarcely recognized. In this study, rare Actinobacteria from marine sediments were isolated from the Valparaíso bay, Chile, and their potential to produce antibacterial compounds was evaluated....

  4. Culturable diversity and antimicrobial activity of Actinobacteria from marine sediments in Valparaíso bay, Chile

    OpenAIRE

    Claverías, Fernanda P.; Undabarrena, Agustina; González, Myriam; Seeger, Michael; Cámara, Beatriz

    2015-01-01

    Marine-derived Actinobacteria are a source of a broad variety of secondary metabolites with diverse biological activities, such as antibiotics and antitumorals; many of which have been developed for clinical use. Rare Actinobacteria represent an untapped source of new bioactive compounds that have been scarcely recognized. In this study, rare Actinobacteria from marine sediments were isolated from the Valpara?so bay, Chile, and their potential to produce antibacterial compounds was evaluated....

  5. Late Quaternary Biosiliceous Laminated Marine Sediments From Antarctica: Seasonality During a Period of Rapid Climate Change

    Science.gov (United States)

    Pike, J.; Stickley, C. E.; Maddison, E. J.; Leventer, A.; Brachfeld, S.; Domack, E. W.; Dunbar, R. B.; Manley, P. L.; McClennen, C.

    2004-12-01

    The Antarctic ice sheet plays a key role in global oceanic and atmosphere systems. One of the most dynamic regions of the continent is the Antarctic Peninsula (AP) where ecological and cryospheric systems respond rapidly to climate change, such as the last deglaciation ( ˜12-13 kyr BP). Here, deglacial laminated diatom-rich marine sediments are well known, e.g., Palmer Deep (64° S 64° W; ODP Hole 1098A) comprising a distinctive 3 m thick sequence of deglacial `couplet' laminations. The East Antarctic margin (EAM), however, has received less attention than the West Antarctic margin (WAM) in palaeoceanographic studies yet its role in deep ocean circulation and, therefore, the global ocean system is significant. Recent sediment cores recovered from EAM sites during NSF Polar Programs-funded cruise NBP0101 in February and March 2001 (e.g. Mertz Drift \\{66° S 143° E\\}, Svenner Channel \\{69° S 77° E\\} in Prydz Bay, Nielsen Basin \\{67° S 66° E\\} and Iceberg Alley \\{67° S 63° E\\}), reveal that a similar sedimentary facies was deposited along the EAM, in similar geomorphological settings to Palmer Deep, during the same timeframe. These rich sediment archives reveal clues about circum-Antarctic palaeoceanographic change during the last deglaciation, a time of both high silica flux and rapid climate change. Microfabrics and diatom assemblages from scanning electron microscope backscattered and secondary electron imagery analysis of coeval deglacial varves from Palmer Deep (WAM), Mertz-Ninnis Trough and Iceberg Alley (EAM) are presented and compared. The varves from these localities are characterised by laminae to thin beds of orange-brown diatom ooze up to ˜8cm thick alternating with blue-grey diatom-bearing terrigenous sediments up to ˜4cm thick. The orange-brown oozes are dominated by resting spores and vegetative valves of Hyalochaete Chaetoceros spp., resulting from spring sedimentation associated with stratified surface waters promoting exceptionally

  6. Measuring Dissolved Oxygen Quantitatively. Collecting and Cultivating Marine Bacteria. To Recognize, Record, and Analyze Characteristics of a Sandy Beach Environment. Quantitative and Qualitative Analysis of Phosphate in Water. Learning Experiences for Coastal and Oceanic Awareness Studies, Nos. 307, 309, 310, 313. [Project COAST].

    Science.gov (United States)

    Delaware Univ., Newark. Coll. of Education.

    Included are four activity units: (1) Measuring Dissolved Oxygen Quantitatively; (2) Collecting and Cultivating Marine Bacteria; (3) To Recognize, Record, and Analyze Characteristics of a Sandy Beach Environment; and (4) Quantitative and Qualitative Analysis of Phosphate in Water. All the activities are designed to be used by secondary school…

  7. Impact of Extraction Methods on the Detectable Protein Complement of Metaproteomic Analyses of Marine Sediments.

    Science.gov (United States)

    Wöhlbrand, Lars; Feenders, Christoph; Nachbaur, Jessica; Freund, Holger; Engelen, Bert; Wilkes, Heinz; Brumsack, Hans-Jürgen; Rabus, Ralf

    2017-11-01

    Metaproteomic analysis targets proteins, the catalytic entities in the habitat, thereby providing direct insights into the metabolic activity of the community studied. A major challenge still remaining for metaproteomics is the effective and comprehensive extraction of proteins from environmental samples, due to their high complexity with respect to organismic diversity and abundance range. Moreover, in certain habitats, the inherent matrix may interfere with protein extraction. In recent years, several studies reported different protein extraction methods for soils known for their complex geochemistry, but only three analyzed marine sediments that generally comprise different though similarly complex geochemistry. In this study, the impact of four different extraction methods was investigated for coastal North Sea and deep sea Pacific Ocean sediments. The extraction methods comprised (i) phenol, (ii) SDS, (iii) a mixture of SDS and phenol, and (iv) urea and thiourea. Prior to extraction, a cell and protein standard (CPS) was added to the sediment samples to trace recovery of proteins from different subcellular locations as well as dissolved BSA. While each extraction method detected distinct peptide complements, SDS-phenol extraction generally achieved highest protein yield and most comprehensive CPS protein identification. Application of two different methods was shown to further improve proteome coverage. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Wave Glider Monitoring of Sediment Transport and Dredge Plumes in a Shallow Marine Sandbank Environment.

    Directory of Open Access Journals (Sweden)

    Vera Van Lancker

    Full Text Available As human pressure on the marine environment increases, safeguarding healthy and productive seas increasingly necessitates integrated, time- and cost-effective environmental monitoring. Employment of a Wave Glider proved very useful for the study of sediment transport in a shallow sandbank area in the Belgian part of the North Sea. During 22 days, data on surface and water-column currents and turbidity were recorded along 39 loops around an aggregate-extraction site. Correlation with wave and tidal-amplitude data allowed the quantification of current- and wave-induced advection and resuspension, important background information to assess dredging impacts. Important anomalies in suspended particulate matter concentrations in the water column suggested dredging-induced overflow of sediments in the near field (i.e., dynamic plume, and settling of finer-grained material in the far field (i.e., passive plume. Capturing the latter is a successful outcome to this experiment, since the location of dispersion and settling of a passive plume is highly dependent on the ruling hydro-meteorological conditions and thus difficult to predict. Deposition of the observed sediment plumes may cause habitat changes in the long-term.

  9. Wave Glider Monitoring of Sediment Transport and Dredge Plumes in a Shallow Marine Sandbank Environment.

    Science.gov (United States)

    Van Lancker, Vera; Baeye, Matthias

    2015-01-01

    As human pressure on the marine environment increases, safeguarding healthy and productive seas increasingly necessitates integrated, time- and cost-effective environmental monitoring. Employment of a Wave Glider proved very useful for the study of sediment transport in a shallow sandbank area in the Belgian part of the North Sea. During 22 days, data on surface and water-column currents and turbidity were recorded along 39 loops around an aggregate-extraction site. Correlation with wave and tidal-amplitude data allowed the quantification of current- and wave-induced advection and resuspension, important background information to assess dredging impacts. Important anomalies in suspended particulate matter concentrations in the water column suggested dredging-induced overflow of sediments in the near field (i.e., dynamic plume), and settling of finer-grained material in the far field (i.e., passive plume). Capturing the latter is a successful outcome to this experiment, since the location of dispersion and settling of a passive plume is highly dependent on the ruling hydro-meteorological conditions and thus difficult to predict. Deposition of the observed sediment plumes may cause habitat changes in the long-term.

  10. Interactions between benthic copepods, bacteria and diatoms promote nitrogen retention in intertidal marine sediments.

    Directory of Open Access Journals (Sweden)

    Willem Stock

    Full Text Available The present study aims at evaluating the impact of diatoms and copepods on microbial processes mediating nitrate removal in fine-grained intertidal sediments. More specifically, we studied the interactions between copepods, diatoms and bacteria in relation to their effects on nitrate reduction and denitrification. Microcosms containing defaunated marine sediments were subjected to different treatments: an excess of nitrate, copepods, diatoms (Navicula sp., a combination of copepods and diatoms, and spent medium from copepods. The microcosms were incubated for seven and a half days, after which nutrient concentrations and denitrification potential were measured. Ammonium concentrations were highest in the treatments with copepods or their spent medium, whilst denitrification potential was lowest in these treatments, suggesting that copepods enhance dissimilatory nitrate reduction to ammonium over denitrification. We hypothesize that this is an indirect effect, by providing extra carbon for the bacterial community through the copepods' excretion products, thus changing the C/N ratio in favour of dissimilatory nitrate reduction. Diatoms alone had no effect on the nitrogen fluxes, but they did enhance the effect of copepods, possibly by influencing the quantity and quality of the copepods' excretion products. Our results show that small-scale biological interactions between bacteria, copepods and diatoms can have an important impact on denitrification and hence sediment nitrogen fluxes.

  11. Interactions between Benthic Copepods, Bacteria and Diatoms Promote Nitrogen Retention in Intertidal Marine Sediments

    Science.gov (United States)

    Stock, Willem; Heylen, Kim; Sabbe, Koen; Willems, Anne; De Troch, Marleen

    2014-01-01

    The present study aims at evaluating the impact of diatoms and copepods on microbial processes mediating nitrate removal in fine-grained intertidal sediments. More specifically, we studied the interactions between copepods, diatoms and bacteria in relation to their effects on nitrate reduction and denitrification. Microcosms containing defaunated marine sediments were subjected to different treatments: an excess of nitrate, copepods, diatoms (Navicula sp.), a combination of copepods and diatoms, and spent medium from copepods. The microcosms were incubated for seven and a half days, after which nutrient concentrations and denitrification potential were measured. Ammonium concentrations were highest in the treatments with copepods or their spent medium, whilst denitrification potential was lowest in these treatments, suggesting that copepods enhance dissimilatory nitrate reduction to ammonium over denitrification. We hypothesize that this is an indirect effect, by providing extra carbon for the bacterial community through the copepods' excretion products, thus changing the C/N ratio in favour of dissimilatory nitrate reduction. Diatoms alone had no effect on the nitrogen fluxes, but they did enhance the effect of copepods, possibly by influencing the quantity and quality of the copepods' excretion products. Our results show that small-scale biological interactions between bacteria, copepods and diatoms can have an important impact on denitrification and hence sediment nitrogen fluxes. PMID:25360602

  12. Uptake of PCBs contained in marine sediments by the green macroalga Ulva rigida.

    Science.gov (United States)

    Cheney, Donald; Rajic, Ljiljana; Sly, Elizabeth; Meric, Dogus; Sheahan, Thomas

    2014-11-15

    The uptake of PCBs contained in marine sediments by the green macroalga Ulva rigida was investigated in both laboratory and field experiments. Under laboratory conditions, total PCBs (tPCBs) uptake was significantly greater in live vs dead plants. The concentration of tPCB taken up in live plants was greatest in the first 24h (1580 μg kg(-1) dry weight), and then increased at a lower rate from day 2 to 14. Dead plants had a significantly lower tPCB concentration after 24h (609 μg kg(-1) dry weight) and lower uptake rate through day 14. Lesser chlorinated PCB congeners (below 123) made up the majority of PCBs taken up. Congener composition in both laboratory and field experiments was correlated to congener logKow value and sediment content. Field experiments showed that Ulva plants could concentrate PCBs to 3.9 mg kg(-1) in 24h. Thus, U. rigida is capable of removing PCBs in sediments at a rapid rate. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Genomes of two new ammonia-oxidizing archaea enriched from deep marine sediments.

    Directory of Open Access Journals (Sweden)

    Soo-Je Park

    Full Text Available Ammonia-oxidizing archaea (AOA are ubiquitous and abundant and contribute significantly to the carbon and nitrogen cycles in the ocean. In this study, we assembled AOA draft genomes from two deep marine sediments from Donghae, South Korea, and Svalbard, Arctic region, by sequencing the enriched metagenomes. Three major microorganism clusters belonging to Thaumarchaeota, Epsilonproteobacteria, and Gammaproteobacteria were deduced from their 16S rRNA genes, GC contents, and oligonucleotide frequencies. Three archaeal genomes were identified, two of which were distinct and were designated Ca. "Nitrosopumilus koreensis" AR1 and "Nitrosopumilus sediminis" AR2. AR1 and AR2 exhibited average nucleotide identities of 85.2% and 79.5% to N. maritimus, respectively. The AR1 and AR2 genomes contained genes pertaining to energy metabolism and carbon fixation as conserved in other AOA, but, conversely, had fewer heme-containing proteins and more copper-containing proteins than other AOA. Most of the distinctive AR1 and AR2 genes were located in genomic islands (GIs that were not present in other AOA genomes or in a reference water-column metagenome from the Sargasso Sea. A putative gene cluster involved in urea utilization was found in the AR2 genome, but not the AR1 genome, suggesting niche specialization in marine AOA. Co-cultured bacterial genome analysis suggested that bacterial sulfur and nitrogen metabolism could be involved in interactions with AOA. Our results provide fundamental information concerning the metabolic potential of deep marine sedimentary AOA.

  14. Time Matters: Increasing the Efficiency of Antarctic Marine Geology and Paleoceanography Expeditions by Providing Improved Sediment Chronology

    Science.gov (United States)

    Rosenheim, B. E.; Domack, E. W.; Shevenell, A.; Subt, C.

    2015-12-01

    To maximize the areal extent of Antarctic sedimentary records of past deglaciation, it is necessary to ensure more sediment cores can be adequately dated. Antarctic margin sediment is challenging to date due to the lack of preserved calcium carbonate, but the records contained in these sediments readily recount the history of deglaciation. Recent and continued development of new chronological methods for Antarctic margin sediments have allowed better use of the efforts of marine geological coring expeditions to the region. The development of Ramped PyrOx radiocarbon dating has allowed us to 1. improve dates in deglacial sediments where no carbonate is preserved, 2. date glacial sediments lying below the tills marking the last glaciation, and 3. compile core chronologies into a regional framework of ice shelf collapse that has eluded many marine geology campaigns over the last few decades. These advances in a fundamental aspect of geological sciences will put the U.S. and international community on a better foothold to interpret the past as it relates to our warming future. We will present these advances in chronology as well as the science that is enabled by them, while arguing that the future of Antarctic marine science also depends on investments in shore-based technologies that come at a relatively low cost.

  15. Effects of conventional and biodegradable microplastics on a marine ecosystem engineer (Arenicola marina) and sediment nutrient cycling.

    Science.gov (United States)

    Green, Dannielle Senga; Boots, Bas; Sigwart, Julia; Jiang, Shan; Rocha, Carlos

    2016-01-01

    Effects of microplastic pollution on benthic organisms and ecosystem services provided by sedimentary habitats are largely unknown. An outdoor mesocosm experiment was done to realistically assess the effects of three different types of microplastic pollution (one biodegradable type; polylactic acid and two conventional types; polyethylene and polyvinylchloride) at increasing concentrations (0.02, 0.2 and 2% of wet sediment weight) on the health and biological activity of lugworms, Arenicola marina (Linnaeus, 1758), and on nitrogen cycling and primary productivity of the sediment they inhabit. After 31 days, A. marina produced less casts in sediments containing microplastics. Metabolic rates of A. marina increased, while microalgal biomass decreased at high concentrations, compared to sediments with low concentrations or without microplastics. Responses were strongest to polyvinylchloride, emphasising that different materials may have differential effects. Each material needs to be carefully evaluated in order to assess their risks as microplastic pollution. Overall, both conventional and biodegradable microplastics in sandy sediments can affect the health and behaviour of lugworms and directly or indirectly reduce primary productivity of these habitats. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Organotin persistence in contaminated marine sediments and porewaters: In situ degradation study using species-specific stable isotopic tracers

    Energy Technology Data Exchange (ETDEWEB)

    Furdek, Martina; Mikac, Nevenka [Division for Marine and Environmental Research, Rudjer Boskovic Institute, Bijenicka 54, Zagreb (Croatia); Bueno, Maite; Tessier, Emmanuel; Cavalheiro, Joana [Laboratoire de Chimie Analytique Bio-inorganique et Environnement, Institut Pluridisciplinaire de Recherche sur l’Environnement et les Matériaux, CNRS UMR 5254, Université de Pau et des Pays de l’Adour, Hélioparc Pau Pyrénées, 2, Av. P. Angot, 64053 Pau Cedex 9 (France); Monperrus, Mathilde, E-mail: mathilde.monperrus@univ-pau.fr [Laboratoire de Chimie Analytique Bio-inorganique et Environnement, Institut Pluridisciplinaire de Recherche sur l’Environnement et les Matériaux, CNRS UMR 5254, Université de Pau et des Pays de l’Adour, Hélioparc Pau Pyrénées, 2, Av. P. Angot, 64053 Pau Cedex 9 (France)

    2016-04-15

    Highlights: • Limiting step in OTC degradation in sediments is their desorption into porewater. • TBT persistence in contaminated sediments increases in sediments rich in organic matter. • DBT does not accumulate in sediments as degradation product of TBT. • TBT and DBT degradation in porewaters occurs with half-lives from 2.9 to 9.2 days. • PhTs degradation is slower than BuTs degradation in oxic porewaters. - Abstract: This paper provides a comprehensive study of the persistence of butyltins and phenyltins in contaminated marine sediments and presents the first data on their degradation potentials in porewaters. The study’s aim was to explain the different degradation efficiencies of organotin compounds (OTC) in contaminated sediments. The transformation processes of OTC in sediments and porewaters were investigated in a field experiment using species-specific, isotopically enriched organotin tracers. Sediment characteristics (organic carbon content and grain size) were determined to elucidate their influence on the degradation processes. The results of this study strongly suggest that a limiting step in OTC degradation in marine sediments is their desorption into porewaters because their degradation in porewaters occurs notably fast with half-lives of 9.2 days for tributyltin (TBT) in oxic porewaters and 2.9 ± 0.1 and 9.1 ± 0.9 days for dibutyltin (DBT) in oxic and anoxic porewaters, respectively. By controlling the desorption process, organic matter influences the TBT degradation efficiency and consequently defines its persistence in contaminated sediments, which thus increases in sediments rich in organic matter.

  17. Microbial community analysis of deeply buried marine sediments of the New Jersey shallow shelf (IODP Expedition 313).

    Science.gov (United States)

    Breuker, Anja; Stadler, Susanne; Schippers, Axel

    2013-09-01

    The investigated deeply buried marine sediments of the shallow shelf off New Jersey, USA, are characterized by low organic carbon content and total cell counts of Crenarchaeota with 1%, 14%, and 85%, respectively. The typical deep subsurface sediment-associated groups MBG-B, MBG-D, MCG, and SAGMEG were represented in the sediment community. MCG was the dominant group with a high diversity of the isolated 16S rRNA gene sequences. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2012-12-01

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

  19. Orchomenella pinguis (amphipoda-a possible species for heavy metal biomonitoring of marine sediments

    Directory of Open Access Journals (Sweden)

    Lis Bach

    2014-02-01

    Full Text Available Objective: To evaluate the potential local benthic biomonitor organism, Orchomenella pinguis (O. pinguis, for mining contamination by addressing accumulation and toxicity of mining related metals in this arctic marine amphipod. Methods: A toxicity study exposed O. pinguis to four commonly occurring heavy metals (Cd, Cu, Zn and Pb associated to the mining industry in Greenland using: 1 a 5-day water-only bioassay; 2 a water-only bioassay evaluating the response between metal accumulation in O. pinguis and metal concentrations in water during a 5-day period; and finally 3 a sediment bioassay evaluating the response between metal accumulation in O. pinguis and metal concentrations in sediment as a function of time during a 20-day period using different mixtures of mining-contaminated sediments. Results: LC50 values for the four metals were 2.8, 5.4, 10.4 and 21.4 µmol/L, for Cu, Cd, Pb and Zn, respectively, with corresponding modelled metal concentrations of 3.4, 1.0, 11.1 and 6.1 µmol/g dry weight. During the sediment exposure experiments, a similar concentration of Zn did not induce lethal effects at the same level. Conclusions: This study demonstrates that the appliance of metal organism concentrations as an estimate of effects is not a sufficient biomonitor of environmental effects. The organism may sequester metals into cellular compartments thus rendering the metals inert for toxic effects. More studies are needed to investigate effects of metal bioavailability. Additional biomarkers such as effects on functional responses e.g. feeding and burial behavior or effects on reproductive success are suggested in order enhance to the ecological significance.

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

    Science.gov (United States)

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

    1993-01-01

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

  1. Quantification of microbial communities in subsurface marine sediments of the Black Sea and off Namibia

    Directory of Open Access Journals (Sweden)

    Axel eSchippers

    2012-01-01

    Full Text Available Organic-rich subsurface marine sediments were taken by gravity coring up to a depth of 10 meters below seafloor at six stations from the anoxic Black Sea and the Benguela upwelling system off Namibia during the research cruises R/V Meteor 72/5 and 76/1, respectively. The quantitative microbial community composition at various sediment depths was analyzed using total cell counting, CARD-FISH and quantitative real-time PCR (Q-PCR. Total cell counts decreased with depths from 109 – 1010 cells /mL at the sediment surface to 107 – 109 cells /mL below one meter depth. Based on CARD-FISH and Q-PCR analysis overall similar proportions of Bacteria and Archaea were determined. The down core quantitative distribution of prokaryotic and eukaryotic small subunit ribosomal RNA genes as well as functional genes involved in different biogeochemical processes was successfully revealed by Q-PCR. Crenarchaeota and the bacterial candidate division JS-1 and the classes Anaerolineae and Caldilineae of the phylum Chloroflexi were as highly abundant as Archaea and Bacteria, respectively. Less abundant but detectable in most of the samples in high gene copy numbers were Eukarya and the Fe(III- and Mn(IV-reducing bacterial group Geobacteriaceae (off Namibia as well as the functional genes cbbL encoding for the large subunit of Rubisco, the functional genes dsrA and aprA of sulfate-reducers and the gene mcrA of methanogens. Overall the high organic carbon content of the sediments goes along with high cell counts and high gene copy numbers, as well as an equal abundance of Bacteria and Archaea.

  2. LA-ICP-MS as Tool for Provenance Analyses in Arctic Marine Sediments

    Science.gov (United States)

    Wildau, Antje; Garbe-Schönberg, Dieter

    2015-04-01

    The hydraulic transport of sediments is a major geological process in terrestrial and marine systems and is responsible for the loss, redistribution and accumulation of minerals. Provenance analyses are a powerful tool for assessing the origin and dispersion of material in ancient and modern fluvial and marine sediments. Provenance-specific heavy minerals (e.g., zircon, rutile, tourmaline) can therefore be used to provide valuable information on the formation of ore deposits (placer deposits), and the reconstruction of paleogeography, hydrology, climate conditions and developments. The application of provenances analyses for the latter reason is of specific interest, since there is need for research on the progressing climate change, and heavy minerals represent good proxies for the evaluation of recent and past changes in the climate. The study of these fine particles provides information about potential regional or long distance transport paths, glacial / ice drift and current flows, freezing and melting events as well as depositional centers for the released sediments. Classic methods applied for provenance analyses are mapping of the presence / absence of diagnostic minerals, their grain size distribution, modal mineralogy and the analysis of variations in ratio of two or more heavy minerals. Electron microprobe has been established to discover changes in mineral chemistry of individual mineral phases, which can indicate fluctuations or differences in the provenance. All these methods bear the potential of high errors that lower the validity of the provenance analyses. These are for example the misclassification of mineral species due to undistinguishable optical properties or the limitations in the detection / variations of trace elements using the election microprobe. For this case study, marine sediments from the Arctic Ocean have been selected to test if LA-ICP-MS can be established as a key technique for precise and reliable provenance analyses. The Laptev

  3. Turbidite sequences in marine sediments off southern Chile ? records of Quaternary climate - tectonics interactions

    Science.gov (United States)

    Echtler, H. P.; Blumberg, S.; Lamy, F.; Arz, H.; Wiedicke, M.; Haug, G. H.; Oncken, O.

    2007-12-01

    The active continental margin of South America is characterized by frequent, devastating and large-magnitude subduction earthquakes. In this environment the assessment of the history of major past earthquakes is hampered by the short historical and instrumental records. Here, we focus on marine turbidite records from offshore southern Chile that reflect the regional paleoseismic history of the forearc region since late Pleistocene time. The investigated records were retrieved from cores obtained from the Ocean Drilling Program (ODP), site 1232, and SONNE 50SL. The coring locations are at ~ 40ç and ~ 38çS lat, within the Peru-Chile trench, and are characterized by frequent interbedded strata of turbiditic and hemipelagic origin. Importantly, dated sections of the obtained cores indicate a recurrence time between 100 and 200 years for individual turbidite events. On the basis of the sedimentological characteristics and the nature of the active margin of southern Chile, we infer that the turbidites are seismogenic in origin, and represent paleo-earthquakes. However, the long-term changes in turbidite recurrence intervals also appear to be strongly influenced by climate and associated sea-level changes. For example, during the rising sea-level in the Holocene (ACHTUNG: es gab keine h?heren Meeresspiegel, sondern der Meeresspiegel ist seit 14 ka angestiegen) and Marine Isotope Stage (MIS) 5, recurrence of turbiditic layers is substantially higher, primarily reflecting a climate-induced reduction of sediment availability and enhanced slope stability (Dieser Satz ist inhaltlich nicht ganz klar). In addition, changes in the segmentation of tectonic uplift in the forearc and related drainage captures likely influenced the availability of sediment entering the marine realm, possibly determining the postglacial decrease in turbidite frequency. On the other hand, glacial turbidite recurrence times (including MIS 2, MIS 3, cold substages of MIS 5, and MIS 6), are within the

  4. Permian marine sedimentation in northern Chile: new paleontological evidence from the Juan de Morales Formation, and regional paleogeographic implications

    Science.gov (United States)

    Díaz-Martínez, E.; Mamet, B.; Isaacson, P. E.; Grader, G. W.

    2000-11-01

    Permian marine sedimentary rocks that crop out in northern Chile are closely related to the development of a Late Paleozoic magmatic arc. A study of Upper Paleozoic units east of Iquique (20°S) identified three members within the Juan de Morales Formation, each of which were deposited in a different sedimentary environment. A coarse-grained terrigenous basal member represents alluvial sedimentation from a local volcanic source. A mixed carbonate-terrigenous middle member represents coastal and proximal shallow marine sedimentation during a relative sea-level rise related with a global transgression. Preliminary foraminifer biostratigraphy of this middle member identified a late Early Permian (late Artinskian-Kungurian) highly impoverished nodosarid-geinitzinid assemblage lacking fusulines and algae, which is characteristic of temperate cold waters and/or disphotic zone. The upper fine-grained terrigenous member represents shallow marine siliciclastic sedimentation under storm influence. The Juan de Morales Formation consists of continental, coastal and shallow marine sediments deposited at the active western margin of Gondwana at mid to low latitudes. A revised late Early Permian age and similar paleogeography and sedimentary environments are also proposed for the Huentelauquén Formation and related units of northern and central Chile, Arizaro Formation of northwestern Argentina, and equivalent units of southernmost Peru.

  5. Nitrogen cycling and community structure of proteobacterial ß-subgroup ammonia-oxidizing bacteria within polluted marine fish farm sediments

    NARCIS (Netherlands)

    McCaig, A.E.; Phillips, C.B.; Stephen, J.R.; Kowalchuk, G.A.; Harvey, S.M.; Herbert, R.A.; Embley, T.M.; Prosser, J.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

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

    NARCIS (Netherlands)

    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

  7. 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

  8. Community structure, cellular rRNA content, and activity of sulfate-reducing bacteria in marine Arctic sediments

    DEFF Research Database (Denmark)

    Ravenschlag, K.; Sahm, K.; Knoblauch, C.

    2000-01-01

    The community structure of sulfate-reducing bacteria (SRB) of a marine Arctic sediment (Smeerenburg-fjorden, Svalbard) a-as characterized by both fluorescence in situ hybridization (FISH) and rRNA slot blot hybridization by using group- and genus-specific 16S rRNA-targeted oligonucleotide probes...

  9. Experimental evidence for in situ natural attenuation of 2,4- and 2,6-dinitrotoluene in marine sediment.

    Science.gov (United States)

    Yang, Hong; Halasz, Annamaria; Zhao, Jian-Shen; Monteil-Rivera, Fanny; Hawari, Jalal

    2008-01-01

    Dinitrotoluenes (DNTs) are widely used in the manufacturing of explosives and propellants hence causing contamination of several terrestrial and aquatic environments. The present study describes biotransformation of 2,4-DNT and 2,6-DNT in marine sediment sampled from a shipwreck site near Halifax Harbour. Incubation of either 2,4-DNT or 2,6-DNT in anaerobic sediment slurries (10% w/v) at 10 degrees C led to the reduction of both DNTs to their corresponding diaminotoluene (2,4-DAT and 2,6-DAT) via the intermediary formation of their monoamine derivatives (ANTs). The production of diaminotoluene was enhanced in the presence of lactate for both DNT isomers. Using [(14)C]-2,4-DNT less than 1% mineralization was observed as determined by liberated (14)CO(2). Sorption of DNTs, ANTs, and DATs was thus investigated to learn of their fate in marine sediments. Under anaerobic conditions, sorption followed the order: DNTs (K(d)=8.3-11.7lkg(-1))>ANTs (K(d)=4.5-7.0lkg(-1))>DATs (K(d)=3.8-4.5lkg(-1)). Incubation of 2,4-DAT in aerobic sediment led to rapid disappearance from the aqueous phase. LC/MS analysis of the aqueous phase and the acetone sediment extract showed the formation of azo- and hydrazo-dimers and trimers, as well as unidentified polymers. Experiments with radiolabelled 2,4-DAT showed a mass balance distributed as follows: 22% in the aqueous phase, 24% in acetone extracts, and 50% irreversibly bound to sediment. We concluded that DNT in anoxic marine sediment can undergo in situ natural attenuation by reduction to DAT followed by oxidative coupling to hydrazo-oligomers or irreversible binding to sediment.

  10. 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.

  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. The fate of fixed nitrogen in marine sediments with low organic loading: an in situ study

    DEFF Research Database (Denmark)

    Bonaglia, Stefano; Hylén, Astrid; Rattray, Jane E.

    2016-01-01

    Given the increasing impacts of human activities on global nitrogen (N) cycle, investigations on N transformation processes in the marine environment have drastically increased in the last years. Benthic N cycling has mainly been studied in anthropogenically impacted estuaries and coasts, while its...... understanding in oligotrophic systems is still scarce. Here we report on rates of denitrification, anammox and dissimilatory nitrate reduction to ammonium (DNRA) studied by in situ incubations with benthic chamber landers during two cruises to the Gulf of Bothnia (GOB), a cold, oligotrophic basin located...... the southern and central eutrophic Baltic Sea and other temperate estuaries and coasts in Europe. Therefore, our results contrast with the view that DNRA is negligible in cold and well-oxygenated sediments with low organic carbon loads. However, the mechanisms behind the variability in DNRA rates between our...

  13. The fate of fixed nitrogen in marine sediments with low organic loading: an in situ study

    DEFF Research Database (Denmark)

    Bonaglia, Stefano; Hylén, Astrid; Rattray, Jane E.

    2017-01-01

    Given the increasing impacts of human activities on global nitrogen (N) cycle, investigations on N transformation processes in the marine environment have drastically increased in the last years. Benthic N cycling has mainly been studied in anthropogenically impacted estuaries and coasts, while its...... understanding in oligotrophic systems is still scarce. Here we report on rates of denitrification, anammox and dissimilatory nitrate reduction to ammonium (DNRA) studied by in situ incubations with benthic chamber landers during two cruises to the Gulf of Bothnia (GOB), a cold, oligotrophic basin located...... the southern and central eutrophic Baltic Sea and other temperate estuaries and coasts in Europe. Therefore, our results contrast with the view that DNRA is negligible in cold and well-oxygenated sediments with low organic carbon loads. However, the mechanisms behind the variability in DNRA rates between our...

  14. 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  = -33...... yield was rarely less than -20 kJ mol-1 and was mostly rather constant throughout this zone. The kinetic drive was highest at the lower part of the SMTZ, matching the occurrence of maximum AOM rates. The results show that the location of maximum AOM rates is determined by a combination of thermodynamic...... and kinetic drive, whereas the rate activity mainly depends on kinetic regulation....

  15. Quicklime (CaO) Stabilization of fine-grained marine sediments in low temperature areas

    DEFF Research Database (Denmark)

    Skels, Peteris; Ingeman-Nielsen, Thomas; Jørgensen, Anders Stuhr

    2011-01-01

    in a soil-CaO mixture was determined using a number of laboratory methods, such as pH test, consistency limit analysis, degree of compaction, and short term California Bearing Ratio (CBR) values. The study also numerically demonstrates a long term strength development of the soil-CaO mixture at 1°C and 10°C...... curing temperatures, comparing stabilization effectiveness between low and normal soil temperature conditions.......This study presents laboratory testing on quicklime (CaO) stabilization of fine-grained marine sediments in low temperature areas. The soil was sampled on the Fossil Plain in Kangerlussuaq, Greenland, and analyzed in the laboratory at Technical University of Denmark (DTU). The optimum CaO content...

  16. Phospholipid-derived fatty acids and quinones as markers for bacterial biomass and community structure in marine sediments.

    Science.gov (United States)

    Kunihiro, Tadao; Veuger, Bart; Vasquez-Cardenas, Diana; Pozzato, Lara; Le Guitton, Marie; Moriya, Kazuyoshi; Kuwae, Michinobu; Omori, Koji; Boschker, Henricus T S; van Oevelen, Dick

    2014-01-01

    Phospholipid-derived fatty acids (PLFA) and respiratory quinones (RQ) are microbial compounds that have been utilized as biomarkers to quantify bacterial biomass and to characterize microbial community structure in sediments, waters, and soils. While PLFAs have been widely used as quantitative bacterial biomarkers in marine sediments, applications of quinone analysis in marine sediments are very limited. In this study, we investigated the relation between both groups of bacterial biomarkers in a broad range of marine sediments from the intertidal zone to the deep sea. We found a good log-log correlation between concentrations of bacterial PLFA and RQ over several orders of magnitude. This relationship is probably due to metabolic variation in quinone concentrations in bacterial cells in different environments, whereas PLFA concentrations are relatively stable under different conditions. We also found a good agreement in the community structure classifications based on the bacterial PLFAs and RQs. These results strengthen the application of both compounds as quantitative bacterial biomarkers. Moreover, the bacterial PLFA- and RQ profiles revealed a comparable dissimilarity pattern of the sampled sediments, but with a higher level of dissimilarity for the RQs. This means that the quinone method has a higher resolution for resolving differences in bacterial community composition. Combining PLFA and quinone analysis as a complementary method is a good strategy to yield higher resolving power in bacterial community structure.

  17. Dispersed Ash in Marine Sediment: An Overview Towards Unraveling the 'Missing Volcanic Record'

    Science.gov (United States)

    Murray, R. W.; Scudder, R.; Kutterolf, S.; Schindlbeck, J.

    2013-12-01

    Volcanic ash occurs in marine sediment both as discrete layers as well as isolated grains and shards dispersed throughout the bulk sediment, and with highly variable grain sizes. The study of this dispersed component has lagged behind the sophisticated petrographic, sedimentologic, geochemical, and isotopic assessment of the ash layer record. For example, while decades of smear-slide studies of bulk sediment in volcanic-rich regimes have presented visual estimations of the abundance of 'volcanic glass', 'shards', and/or other components, the quantitative importance of the dispersed ash and/or the cryptotephra component remains largely unconstrained on local, regional, and global scales. Chemical and isotopic characterization of this dispersed component has remained elusive. Building on earlier work, research in the 1970s began documenting the importance of dispersed ash and its alteration products. This dispersed ash is the result of the bioturbation of pre-existing discrete layers, the settling of airborne ash, distribution from subaqueous eruptions, and other mechanisms. Compared to the often visually stunning ash layer records, which in certain settings can leave single layers with thicknesses of 10s of cm, the dispersed ash component and cryptotephra layers are unable to be visually differentiated from detrital clay. Furthermore, its extremely fine grain size is an additional hindrance to quantification of its abundance and the identification of source. More completely characterizing the total ash inventory (that is, the dispersed ash in addition to the ash layers) will contribute significantly to studies of marine and terrestrial volcanism at many scales, geochemical mass balances, arc evolution, hydration of marine sediment during alteration, atmospheric circulation, putative relationships between volcanism and climate, and other key components of the earth-ocean-atmosphere system. Beginning with work in the Caribbean Sea and progressing to the northwest

  18. 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.

  19. 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

    2015-10-23

    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. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  20. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Carotenoid diagenesis in recent marine sediments--I. The Peru continental shelf (15°S, 75°W) *

    Science.gov (United States)

    Repeta, Daniel J.; Gagosian, Robert B.

    1987-04-01

    We report here the distribution of carotenoids in Peru marine surface sediments, including partial identification of 37 pigments, 33 of which have not been previously reported to occur in marine sediments. Our analysis demonstrates that zooplanktonic crustacea, diatoms, dinoflagellates, cryptomonads, purple nonsulfur photosynthetic bacteria, and unidentified species of photosynthetic bacteria are contributors to sedimentary organic matter. Fucoxanthin, fucoxanthinol, diadinoxanthin, peridinin and peridininol, the principal carotenoids of diatoms and dinoflagellates observed in sediment traps, are nearly absent from our sample, even though these phytoplankton are the primary source of organic matter. We attribute this to the presence of 5,6 epoxides in these pigments, a feature which causes rapid cleavage of the polyene and fragmentation to low molecular weight compounds.

  2. Carotenoid diagenesis in recent marine sediments. I. The Peru continental shelf (15/sup 0/S, 75/sup 0/W)

    Energy Technology Data Exchange (ETDEWEB)

    Repeta, D.J.; Gagosian, R.B.

    1987-04-01

    The authors report here the distribution of carotenoids in Peru marine surface sediments, including partial identification of 37 pigments, 33 of which have not been previously reported to occur in marine sediments. Their analysis demonstrates that zooplanktonic crustacea, diatoms, dinoflagellates, cryptomonads, purple nonsulfur photosynthetic bacteria, and unidentified species of photosynthetic bacteria are contributors to sedimentary organic matter. Fucoxanthin, fucoxanthinol, diadinoxanthin, peridinin and peridininol, the principal carotenoids of diatoms and dinoflagellates observed in sediment traps, are nearly absent from their sample, even though these phytoplankton are the primary source of organic matter. They attribute this to the presence of 5,6 epoxides in these pigments, a feature which causes rapid cleavage of the polyene and fragmentation to low molecular weight compounds.

  3. 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

  4. Macromolecular composition of terrestrial and marine organic matter in sediments across the East Siberian Arctic Shelf

    Directory of Open Access Journals (Sweden)

    R. B. Sparkes

    2016-10-01

    Full Text Available Mobilisation of terrestrial organic carbon (terrOC from permafrost environments in eastern Siberia has the potential to deliver significant amounts of carbon to the Arctic Ocean, via both fluvial and coastal erosion. Eroded terrOC can be degraded during offshore transport or deposited across the wide East Siberian Arctic Shelf (ESAS. Most studies of terrOC on the ESAS have concentrated on solvent-extractable organic matter, but this represents only a small proportion of the total terrOC load. In this study we have used pyrolysis–gas chromatography–mass spectrometry (py-GCMS to study all major groups of macromolecular components of the terrOC; this is the first time that this technique has been applied to the ESAS. This has shown that there is a strong offshore trend from terrestrial phenols, aromatics and cyclopentenones to marine pyridines. There is good agreement between proportion phenols measured using py-GCMS and independent quantification of lignin phenol concentrations (r2 = 0.67, p < 0.01, n = 24. Furfurals, thought to represent carbohydrates, show no offshore trend and are likely found in both marine and terrestrial organic matter. We have also collected new radiocarbon data for bulk OC (14COC which, when coupled with previous measurements, allows us to produce the most comprehensive 14COC map of the ESAS to date. Combining the 14COC and py-GCMS data suggests that the aromatics group of compounds is likely sourced from old, aged terrOC, in contrast to the phenols group, which is likely sourced from modern woody material. We propose that an index of the relative proportions of phenols and pyridines can be used as a novel terrestrial vs. marine proxy measurement for macromolecular organic matter. Principal component analysis found that various terrestrial vs. marine proxies show different patterns across the ESAS, and it shows that multiple river–ocean transects of surface sediments transition from river-dominated to

  5. Sources and fate of microplastics in marine and beach sediments of the Southern Baltic Sea-a preliminary study.

    Science.gov (United States)

    Graca, Bożena; Szewc, Karolina; Zakrzewska, Danuta; Dołęga, Anna; Szczerbowska-Boruchowska, Magdalena

    2017-03-01

    Microplastics' (particles size ≤5 mm) sources and fate in marine bottom and beach sediments of the brackish are strongly polluted Baltic Sea have been investigated. Microplastics were extracted using sodium chloride (1.2 g cm -3 ). Their qualitative identification was conducted using micro-Fourier-transform infrared spectroscopy (μFT-IR). Concentration of microplastics varied from 25 particles kg -1 d.w. at the open sea beach to 53 particles kg -1  d.w. at beaches of strongly urbanized bay. In bottom sediments, microplastics concentration was visibly lower compared to beach sediments (0-27 particles kg -1  d.w.) and decreased from the shore to the open, deep-sea regions. The most frequent microplastics dimensions ranged from 0.1 to 2.0 mm, and transparent fibers were predominant. Polyester, which is a popular fabrics component, was the most common type of microplastic in both marine bottom (50%) and beach sediments (27%). Additionally, poly(vinyl acetate) used in shipbuilding as well as poly(ethylene-propylene) used for packaging were numerous in marine bottom (25% of all polymers) and beach sediments (18% of all polymers). Polymer density seems to be an important factor influencing microplastics circulation. Low density plastic debris probably recirculates between beach sediments and seawater in a greater extent than higher density debris. Therefore, their deposition is potentially limited and physical degradation is favored. Consequently, low density microplastics concentration may be underestimated using current methods due to too small size of the debris. This influences also the findings of qualitative research of microplastics which provide the basis for conclusions about the sources of microplastics in the marine environment.

  6. Composition, production, and loss of carbohydrates in subtropical shallow subtidal sandy sediments: Rapid processing and long-term retention revealed by 13C-labeling

    NARCIS (Netherlands)

    Oakes, J.M.; Eyre, B.D.; Middelburg, J.J.; Boschker, H.T.S.

    2010-01-01

    The composition and production of carbohydrates (mannose, rhamnose, fucose, galactose, glucose, and xylose) and their transfer among sediment compartments (microphytobenthos [MPB], bacteria, and detritus) was investigated through in situ labeling with 13C-bicarbonate. After 60 h, 13C was found in

  7. 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

  8. Dissolution of fluoride complexes following microwave-assisted hydrofluoric acid digestion of marine sediments.

    Science.gov (United States)

    Muratli, Jesse M; McManus, James; Mix, Alan; Chase, Zanna

    2012-01-30

    Microwave-assisted, hydrofluoric acid digestion is an increasingly common tool for the preparation of marine sediment samples for analysis by a variety of spectrometric techniques. Here we report that analysis of terrigenous-dominated sediment samples occasionally results in anomalously low values for several elements, including Al, Ba, Ca, Mg, and Sr. Measured concentrations of these elements increased with time between sample preparation and sample analysis, reaching stable values after 8-29 days. This lag is explained by the formation and subsequent dissolution of poorly soluble fluoride phases during digestion. Other elements, such as Fe, Mn, and Ti, showed little or no lag and were quickly measurable at a stable value. Full re-dissolution of the least soluble fluorides, which incorporate Al and Mg, requires up to four weeks at room temperature, and this duration can vary among sedimentary matrices. This waiting time can be reduced to 6 days (or shorter) if the samples are heated to ≈ 60°C for 24h. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. 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}.

  10. Fluid flow through reconstituted marine quartz sediments - an interacting lattice gas simulation

    Science.gov (United States)

    Reed, Allen; Braithwaite, Edward; Gettrust, Joe; Pandey, Ras

    2007-03-01

    A porous sediment sample (cylinder of 5.9 mm diameter) is reconstituted in the laboratory using marine quartz sands from the Northern Gulf of Mexico. Digitized computed tomography images of sub-sample (cylinder of 6.5 mm diameter), removed from different regions of the laboratory sample, provide the porous matrix for an interacting lattice gas simulation. A cubic lattice of size 100^3 is used to represent the sediment matrix of the order of 64 mm^3. Different regions of the reconstituted sample are represented by corresponding porous matrices, each with a unique pore distribution. Mobile particles, the constituents of an interacting lattice gas, are used to model the fluid, which flows through the porous media from a source at the bottom to a sink at the top. Fluid particles are driven by their concentration gradient and an external pressure bias against gravity. Variations of the root mean square displacement of each particle (tracer) and that of their center of mass with the time steps, mass transfer and flux are examined as a function of the external pressure bias. Transport properties, including the response of the fluid flux to pressure bias, will be presented.

  11. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Development and application of a marine sediment pore-water toxicity test using Ulva fasciata zoospores

    Science.gov (United States)

    Hooten, Russell L.; Carr, R. Scott

    1998-01-01

    An acute (96 h) pore-water toxicity test protocol using germination and growth of Ulva fasciatazoospores 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 NH3than 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 fasciatazoospore 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.

  13. Forsmark site investigation. Investigation of marine and lacustrine sediment in lakes. Field data 2003

    Energy Technology Data Exchange (ETDEWEB)

    Hedenstroem, Anna [SGU, Uppsala (Sweden)

    2003-04-01

    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.

  14. 234Th analysis of marine sediments via extraction chromatography and liquid scintillation counting.

    Science.gov (United States)

    Nour, Svetlana; Burnett, William C; Horwitz, E Philip

    2002-08-01

    234Th is widely used as a natural tracer for study of biological mixing and particle scavenging processes in the ocean. This naturally occurring nuclide serves this purpose due to its convenient half-life (24.1 days), constant rate of production from 238U dissolved in seawater, and its strong tendency to attach to particles in seawater. As a beta/gamma emitter, 234Th may be determined using low-level gas-flow proportional counting, gamma spectrometry, and liquid scintillation counting (LSC). We describe here a technique which combines Cerenkov counting to evaluate 234Th (via 234Pa) with LSC alpha counting of 230Th added to the samples as a yield tracer. Our separation approach is based on a sample preparation procedure for marine sediments using nitric acid leaching in a "hot block", and extraction chromatography (TEVA x Resin) for Th isolation. Samples are counted in plastic LSC vials, using Ultima Gold AB cocktail, in 1 M H3PO4 media. A series of sediment samples spiked with known amounts of 234Th yielded activities within a few percent of the anticipated values.

  15. Distribution of non-marine diatoms in surface sediments of streams in Socotra Island, Yemen

    Directory of Open Access Journals (Sweden)

    Abdelfattah A. Zalat

    2011-11-01

    Full Text Available Abundance and species composition of non-marine benthic diatom assemblages were studied from surface sediments samples of 11 streams distributed in Socotra Island, located in the northwest Indian Ocean. A total of 145 diatom species, representing 44 genera, were identified. The overall diatom communities appear to be the first recorded off the island. Pennales and non-planktonic taxa were most dominant over centrales and planktonic forms, both in diversity of genera and species. The majority of recognized diatoms are of cosmopolitan distribution. The predominant diatom flora in the surface sediment samples follow: Synedra ulna, Synedra longissima, Encyonema caespitosum, Encyonema silesiacum, Encyonemopsis microcephala, Mastogloia braunii, Mastogloia dansei, Mastogloia elliptica, Navicula cryptocephala, Navicula cryptotenella, Navicula rhynchocephala, Navicula cincta, Nitzschia amphibian, Nitzschia frustulum, Nitzschia perminuta, Cocconeis placentula, Pleurosira laevis and Staurosirella pinnata. These are found in addition to the common occurrence of Amphora coffeaeformis, Amphora Montana, Anomoeoneis sphaerophora, Cyclotella meneghiniana, Cymbella affinis, Diploneis elliptica, Encyonema mesianum, Diploneis smithii, Gomphonema gracile, Gomphonema parvulum, Kobayasia subtilissima, Mastogloia smithii, Navicula minuscule, Navicula notha, Navicula tenelloides, Nitzschia obtuse, Nitzschia palea, Nitzschia scalaris, Synedra nana, Tryblionella acuminate, Tryblionella granulate and Tryblionella punctata. Multivariate statistical techniques including detrended correspondence and cluster analyses were used to summarize changes in the diatom assemblages present in the examined streams. The results indicated six major diatom assemblages with a variation in dominant species. Each assemblage reflects distinctive environmental conditions based on salinity preference of the recognized and dominant.

  16. Marine sediment cores database for the Mediterranean Basin: a tool for past climatic and environmental studies

    Science.gov (United States)

    Alberico, I.; Giliberti, I.; Insinga, D. D.; Petrosino, P.; Vallefuoco, M.; Lirer, F.; Bonomo, S.; Cascella, A.; Anzalone, E.; Barra, R.; Marsella, E.; Ferraro, L.

    2017-06-01

    Paleoclimatic data are essential for fingerprinting the climate of the earth before the advent of modern recording instruments. They enable us to recognize past climatic events and predict future trends. Within this framework, a conceptual and logical model was drawn to physically implement a paleoclimatic database named WDB-Paleo that includes the paleoclimatic proxies data of marine sediment cores of the Mediterranean Basin. Twenty entities were defined to record four main categories of data: a) the features of oceanographic cruises and cores (metadata); b) the presence/absence of paleoclimatic proxies pulled from about 200 scientific papers; c) the quantitative analysis of planktonic and benthonic foraminifera, pollen, calcareous nannoplankton, magnetic susceptibility, stable isotopes, radionuclides values of about 14 cores recovered by Institute for Coastal Marine Environment (IAMC) of Italian National Research Council (CNR) in the framework of several past research projects; d) specific entities recording quantitative data on δ18O, AMS 14C (Accelerator Mass Spectrometry) and tephra layers available in scientific papers. Published data concerning paleoclimatic proxies in the Mediterranean Basin are recorded only for 400 out of 6000 cores retrieved in the area and they show a very irregular geographical distribution. Moreover, the data availability decreases when a constrained time interval is investigated or more than one proxy is required. We present three applications of WDB-Paleo for the Younger Dryas (YD) paleoclimatic event at Mediterranean scale and point out the potentiality of this tool for integrated stratigraphy studies.

  17. Marine sediment cores database for the Mediterranean Basin: a tool for past climatic and environmental studies

    Directory of Open Access Journals (Sweden)

    Alberico I.

    2017-06-01

    Full Text Available Paleoclimatic data are essential for fingerprinting the climate of the earth before the advent of modern recording instruments. They enable us to recognize past climatic events and predict future trends. Within this framework, a conceptual and logical model was drawn to physically implement a paleoclimatic database named WDB-Paleo that includes the paleoclimatic proxies data of marine sediment cores of the Mediterranean Basin. Twenty entities were defined to record four main categories of data: a the features of oceanographic cruises and cores (metadata; b the presence/absence of paleoclimatic proxies pulled from about 200 scientific papers; c the quantitative analysis of planktonic and benthonic foraminifera, pollen, calcareous nannoplankton, magnetic susceptibility, stable isotopes, radionuclides values of about 14 cores recovered by Institute for Coastal Marine Environment (IAMC of Italian National Research Council (CNR in the framework of several past research projects; d specific entities recording quantitative data on δ18O, AMS 14C (Accelerator Mass Spectrometry and tephra layers available in scientific papers. Published data concerning paleoclimatic proxies in the Mediterranean Basin are recorded only for 400 out of 6000 cores retrieved in the area and they show a very irregular geographical distribution. Moreover, the data availability decreases when a constrained time interval is investigated or more than one proxy is required. We present three applications of WDB-Paleo for the Younger Dryas (YD paleoclimatic event at Mediterranean scale and point out the potentiality of this tool for integrated stratigraphy studies.

  18. 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.

  19. STUDY OF THE SEDIMENTATION TREND IN THE PROSPECTIVE AREA OF PORT OF MARINE CENTER, CIREBON BASED ON REMOTE SENSING DATA

    Directory of Open Access Journals (Sweden)

    Undang Hernawan

    2017-07-01

    Full Text Available A coastal zone is the interface between the land and water that influenced by both of them. Coastal dynamic is influenced by many factors from land and sea, such as sedimentation and current. In order to support marine facility, Marine Geological Institute of Indonesia (MGI plan to build a port. The prospective area is behind MGI office at Cirebon. This study use multi temporal remote sensing data in order to observe trend of coastline change around MGI. Based on the interpretation of the data, there are sedimentation around the MGI water and abrasion due to the presence of Kejawanan’s jetty and Kalijaga River. The result also shows that the current in this region is moving from southeast to northwest. The presence of the Kejawanan’s jetty stymies the movement of sediment. The sediment which is normally moving to the north of the jetty is then trapped on the south side of the structure, so that the sediment precipitates in this region and makes it as the active region of sedimentation and accretion. The presence mangrove conduces to support sedimentation speed and accretion at this region, because of his function as the catchment area. Abrasion occurs in the eastern part of MGI office at the Kalijaga river mouth within the bay. The Kalijaga River mouth is predicted to be the primary source of sedimentation in this area. The coastline change caused by sedimentation will be continuing as long as it is supplied by the sediment. The direction of the sedimentation is parallel to the jetty and it forms ellipsoid, with the sedimentation/accretion region is behind MGI office. The abrasion area is found in Kalijaga River mouth and a small area beside Kalijaga River. In order to build a port, we have to consider this sedimentation process. One of the alternatives to build the port is to make a quay pile model which gives way the current to pass through the other side of the port. Another alternative is to build the port as a pond model but

  20. The Deposition and Accumulation of Microplastics in Marine Sediments and Bottom Water from the Irish Continental Shelf.

    Science.gov (United States)

    Martin, Jake; Lusher, Amy; Thompson, Richard C; Morley, Audrey

    2017-09-07

    Microplastics are widely dispersed throughout the marine environment. An understanding of the distribution and accumulation of this form of pollution is crucial for gauging environmental risk. Presented here is the first record of plastic contamination, in the 5 mm-250 μm size range, of Irish continental shelf sediments. Sixty-two microplastics were recovered from 10 of 11 stations using box cores. 97% of recovered microplastics were found to reside shallower than 2.5 cm sediment depth, with the area of highest microplastic concentration being the water-sediment interface and top 0.5 cm of sediments (66%). Microplastics were not found deeper than 3.5 ± 0.5 cm. These findings demonstrate that microplastic contamination is ubiquitous within superficial sediments and bottom water along the western Irish continental shelf. Results highlight that cores need to be at least 4-5 cm deep to quantify the standing stock of microplastics within marine sediments. All recovered microplastics were classified as secondary microplastics as they appear to be remnants of larger items; fibres being the principal form of microplastic pollution (85%), followed by broken fragments (15%). The range of polymer types, colours and physical forms recovered suggests a variety of sources. Further research is needed to understand the mechanisms influencing microplastic transport, deposition, resuspension and subsequent interactions with biota.

  1. Seasonality and depth distribution of the abundance and activity of ammonia oxidizing microorganisms in marine coastal sediments (North Sea).

    Science.gov (United States)

    Lipsewers, Yvonne A; Bale, Nicole J; Hopmans, Ellen C; Schouten, Stefan; Sinninghe Damsté, Jaap S; Villanueva, Laura

    2014-01-01

    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 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.

  2. 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.

  3. 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

  4. Sandy desertification cycles in the southwestern Mu Us Desert in China over the past 80 years recorded based on nebkha sediments

    Science.gov (United States)

    Li, Jinchang; Zhao, Yanfang; Liu, Haixia; Su, Zhizhu

    2016-03-01

    Sandy desertification (SDN) cycles in the southwestern Mu Us Desert since the late 1920s were recorded based on the evolution of Nitraria tangutorum nebkhas. Particle size changes of the nebkha excavated during the study, together with AMS 14C and 137Cs dating controls, indicated that the SDN of the study area was reverse on the whole over the past 80 years, but multiple SDN cycles also occurred. SDN mainly occurred during the late 1920s to the early 1940s, late 1940s to early 1950s, late 1950s to early 1960s, mid- and late 1980s, and early 2000s. The formation of nebkhas in the study area was triggered by severe SDN caused by extreme drought events that occurred in the 1920s to the 1930s. Over the past 80 years, the general SDN trend in the southwestern Mu Us Desert was mainly controlled by the westerly circulation strength, and severe SDN resulted mainly from extreme drought events in a large spatial scale, whereas slight SDN cycles were mainly due to local climate fluctuations and human activities.

  5. 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

  6. Thermophilic nitrate-reducing microorganisms prevent sulfate reduction in cold marine sediments incubated at high temperature

    Science.gov (United States)

    Nepomnyashchaya, Yana; Rezende, Julia; Hubert, Casey

    2014-05-01

    Hydrogen sulphide produced during metabolism of sulphate-reducing microorganisms (SRM) is toxic, corrosive and causes detrimental oil reservoir souring. During secondary oil recovery, injecting oil reservoirs with seawater that is rich in sulphate and that also cools high temperature formations provides favourable growth conditions for SRM. Nitrate addition can prevent metabolism of SRM by stimulating nitrate-reducing microorganisms (NRM). The investigations of thermophilic NRM are needed to develop mechanisms to control the metabolism of SRM in high temperature oil field ecosystems. We therefore established a model system consisting of enrichment cultures of cold surface marine sediments from the Baltic Sea (Aarhus Bay) that were incubated at 60°C. Enrichments contained 25 mM nitrate and 40 mM sulphate as potential electron acceptors, and a mixture of the organic substrates acetate, lactate, propionate, butyrate (5 mM each) and yeast extract (0.01%) as potential carbon sources and electron donors. Slurries were incubated at 60°C both with and without initial pasteurization at 80°C for 2 hours. In the enrichments containing both nitrate and sulphate, the concentration of nitrate decreased indicating metabolic activity of NRM. After a four-hour lag phase the rate of nitrate reduction increased and the concentration of nitrate dropped to zero after 10 hours of incubation. The concentration of nitrite increased as the reduction of nitrate progressed and reached 16.3 mM after 12 hours, before being consumed and falling to 4.4 mM after 19-day of incubation. No evidence for sulphate reduction was observed in these cultures during the 19-day incubation period. In contrast, the concentration of sulphate decreased up to 50% after one week incubation in controls containing only sulphate but no nitrate. Similar sulfate reduction rates were seen in the pasteurized controls suggesting the presence of heat resistant SRM, whereas nitrate reduction rates were lower in the

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

    Science.gov (United States)

    Schippers, A.; Jørgensen, B. B.

    2001-03-01

    Oxidation of pyrite (FeS 2) under anaerobic conditions in marine sediments is experimentally shown for the first time. In slurry experiments with 55FeS 2 and a MnO 2 rich marine sediment an oxidation of 55FeS 2 was detected which decreased with depth and decreasing concentration of MnO 2 in the sediment. FeS 2 and iron sulfide (FeS) were oxidized chemically at pH 8 by MnO 2 but not by nitrate or amorphic Fe(III) oxide. Elemental sulfur and sulfate were the only products of FeS oxidation, whereas FeS 2 was oxidized to a variety of sulfur compounds, mainly sulfate plus intermediates such as thiosulfate, trithionate, tetrathionate, and pentathionate. Thiosulfate was oxidized by MnO 2 to tetrathionate while other intermediates were oxidized to sulfate. The reaction products indicate that FeS 2 was oxidized via the "Thiosulfate-mechanism" and FeS via the "Polysulfide-mechanism" (Schippers and Sand, 1999). The processes are summarized by the overall equations: (1) FeS 2+7.5 MnO 2+11 H +→Fe(OH) 3+2 SO 42-+7.5 Mn 2++4 H 2O (2) FeS+1.5 MnO 2+3 H +→Fe(OH) 3+S O+1.5 Mn 2+ For FeS 2 oxidation the reaction rates related to the mineral surface area were 1.02 and 1.12 nmol m -2 s -1 for total dissolved S and total dissolved Fe, respectively. Since these values are in the same range as previously published rates for the oxidation of FeS 2 by Fe(III), and since Fe(III) is a well-known oxidant for FeS 2 even at circumneutral pH, Fe(III) is assumed also to be the oxidant for FeS and FeS 2 in the presence of MnO 2. At the iron sulfide surface, Fe(III) is reduced to Fe(II) which is reoxidized to Fe(III) by MnO 2. Thus, an Fe(II)/Fe(III) shuttle should transport electrons between the surfaces of the two solid compounds.

  8. Temporal trends in spheroidal carbonaceous particle deposition derived from annual sediment traps and lake sediment cores and their relationship with non-marine sulphate.

    Science.gov (United States)

    Rose, N L; Monteith, D T

    2005-09-01

    Spheroidal carbonaceous particles (SCPs) provide an unambiguous indication of atmospherically deposited contamination from industrial sources. SCP data from a 12 year annual sediment trapping and coring programme at 14 lakes based on the UK Acid Waters Monitoring Network, were used to consider temporal trends in deposition and to compare these with measured non-marine sulphate fluxes. Results show good temporal coherence across a broad area of northern UK and that SCP deposition levels and are now at their lowest since the 1940s, in agreement with modelled sulphate data. SCP fluxes show reasonable linearity with measured non-marine sulphate depositional fluxes from the nearest UK Acid Deposition Monitoring Network sites, especially over the post-flue-gas desulphurisation period, but comparisons prior to 1972 are not possible due to lack of data. We speculate on whether palaeolimnological SCP data might be used to reconstruct the history of non-marine sulphate fluxes from industrial sources.

  9. Estimating Population Turnover Rates by Relative Quantification Methods Reveals Microbial Dynamics in Marine Sediment.

    Science.gov (United States)

    Kevorkian, Richard; Bird, Jordan T; Shumaker, Alexander; Lloyd, Karen G

    2018-01-01

    The difficulty involved in quantifying biogeochemically significant microbes in marine sediments limits our ability to assess interspecific interactions, population turnover times, and niches of uncultured taxa. We incubated surface sediments from Cape Lookout Bight, North Carolina, USA, anoxically at 21°C for 122 days. Sulfate decreased until day 68, after which methane increased, with hydrogen concentrations consistent with the predicted values of an electron donor exerting thermodynamic control. We measured turnover times using two relative quantification methods, quantitative PCR (qPCR) and the product of 16S gene read abundance and total cell abundance (FRAxC, which stands for "fraction of read abundance times cells"), to estimate the population turnover rates of uncultured clades. Most 16S rRNA reads were from deeply branching uncultured groups, and ∼98% of 16S rRNA genes did not abruptly shift in relative abundance when sulfate reduction gave way to methanogenesis. Uncultured Methanomicrobiales and Methanosarcinales increased at the onset of methanogenesis with population turnover times estimated from qPCR at 9.7 ± 3.9 and 12.6 ± 4.1 days, respectively. These were consistent with FRAxC turnover times of 9.4 ± 5.8 and 9.2 ± 3.5 days, respectively. Uncultured Syntrophaceae , which are possibly fermentative syntrophs of methanogens, and uncultured Kazan-3A-21 archaea also increased at the onset of methanogenesis, with FRAxC turnover times of 14.7 ± 6.9 and 10.6 ± 3.6 days. Kazan-3A-21 may therefore either perform methanogenesis or form a fermentative syntrophy with methanogens. Three genera of sulfate-reducing bacteria, Desulfovibrio , Desulfobacter , and Desulfobacterium , increased in the first 19 days before declining rapidly during sulfate reduction. We conclude that population turnover times on the order of days can be measured robustly in organic-rich marine sediment, and the transition from sulfate-reducing to methanogenic conditions stimulates

  10. 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

  11. Survival Of Magnetic Paleoclimatic Signals From Shallow To Deep Water Marine Redoxomorphic Sediments Across The Northwest Iberian Continental Margin

    Science.gov (United States)

    Mohamed Falcon, K. J.; Rey, D.; Rubio, B.

    2013-05-01

    The magnetic properties of marine sediments on the North Atlantic Iberian continental Margin are strongly dependent on the organic matter input to the sediments and the onset of reductive diagenesis. An onshore-offshore gradient in the intensity of early diagenesis was recently described for the Ría de Vigo, matched by similar patterns in the adjacent rias of Pontevedra and Muros. In the ria environments of NW Iberia, early diagenetic dissolution of magnetic minerals can lead to magnetite half-lives of a few decades, and virtually obliterates any paleoenvironmental signal carried by magnetic minerals, rendering magnetic properties especially useful for the study of early diagenesis dynamics. Early diagenesis has also been identified in sediments of the adjacent continental shelf and deeper environments of the Galician Bank and Iberian Abyssal Plain. However, in these settings, slower dissolution of magnetic minerals allows the preservation of paleoclimatic signatures on different temporal scales. For instance, magnetic properties of continental shelf sediments reveal periods of enhanced rainfall and continental sediment input to the shelf, coincident with the Roman Warm Period and Medieval Climatic Optimum. On the contrary, cold periods are associated with less detrital input. Furthermore, levels of intensified diagenesis are also recorded during cold periods, which have been interpreted as periods of intensified coastal upwelling probably related to long-term North Atlantic Oscillation positive state. At the Galician Bank and Iberian Abyssal Plain sediments early diagenesis is also pervasive, although a paleoceanographic record of changes in the concentration of magnetic minerals transported by water masses flowing from the Portuguese Margin can still be identified. In addition to the progressive dissolution of magnetic minerals with depth, bulk magnetic properties in these deep marine settings show strong dependence on the pelagic carbonate sedimentation and low

  12. Where Has All the Oil Gone? The use of trace metals as potential indicators of oil contamination in marine sediments and beach sands

    Science.gov (United States)

    Roeder, T. K.; Hastings, D. W.; Holzinger, C.; Playle, E.; Brooks, G.; Huettel, M. H.; Kostka, J. E.; Larson, R. A.; Flower, B. P.

    2011-12-01

    We report initial results to determine if select trace metals are effective indicators for the magnitude and spatial extent of Deep Water Horizon (DWH) oil contamination in Gulf of Mexico marine sediments and beach sands. Since crude oil is known to have elevated concentrations of nickel and vanadium, contamination can be detected even after the degradation of oil by measuring enrichment of these metals within marine sediments and beach sands. A sample of crude oil from the Macondo Prospect, source of the Deepwater Horizon (DWH) oil spill, was fully digested and analyzed by inductively coupled plasma mass spectrometry (ICP-MS) at the College of Marine Science, University of South Florida. Results indicate the crude oil is enriched in nickel, vanadium, and cobalt, with concentrations of 0.86 ppm, 2.76 ppm, and 84 ppb, respectively. With this known trace metal enrichment in DWH oil, Gulf of Mexico marine sediments from 400 and 1100m water depth near DeSoto Canyon and beach sands from Pensacola, FL were examined for enrichment of V, Ni, and Co. Both marine sediment and beach sand samples were partially digested with HNO3 before analysis via ICP-MS. With marine sediments, the visually contaminated layer at or near the surface typically exhibited an enrichment in Ni, V, and Co compared to the pristine control sediments. Vanadium and nickel enrichment in marine sediments varied from 10 to 32% and 0 to 22%, respectively. Visible contamination in beach sands was found between 20-60cm beneath the surface and, likewise, showed Ni, V, and Co enrichment up to 33%, 45%, and 100%. This data shows that enrichment of V, Ni, and Co in marine sediments and beach sands may be an effective proxy for contamination even after the degradation of oil. Marine sediments and beach sands will continue to be monitored for trace metal enrichment in an effort to assess the continuing impacts of the DWH spill on the Gulf of Mexico.

  13. 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)

  14. Setting limits for acceptable change in sediment particle size composition: testing a new approach to managing marine aggregate dredging.

    Science.gov (United States)

    Cooper, Keith M

    2013-08-15

    A baseline dataset from 2005 was used to identify the spatial distribution of macrofaunal assemblages across the eastern English Channel. The range of sediment composition found in association with each assemblage was used to define limits for acceptable change at ten licensed marine aggregate extraction areas. Sediment data acquired in 2010, 4 years after the onset of dredging, were used to assess whether conditions remained within the acceptable limits. Despite the observed changes in sediment composition, the composition of sediments in and around nine extraction areas remained within pre-defined acceptable limits. At the tenth site, some of the observed changes within the licence area were judged to have gone beyond the acceptable limits. Implications of the changes are discussed, and appropriate management measures identified. The approach taken in this study offers a simple, objective and cost-effective method for assessing the significance of change, and could simplify the existing monitoring regime. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Spatial variation of potentially toxic elements in different grain size fractions of marine sediments from Gulf of Mannar, India.

    Science.gov (United States)

    Koigoora, Srikanth; Ahmad, Iqbal; Pallela, Ramjee; Janapala, Venkateswara Rao

    2013-09-01

    Marine sediments of the Gulf of Mannar (GoM), India are contaminated by potential toxic elements (PTEs) due to anthropogenic activities posing a risk to the existing fragile coral ecosystem and human health. The current study aimed to assess the distribution of PTEs (arsenic--As; cobalt--Co; copper--Cu, molybdenum--Mo; lead--Pb; and zinc--Zn) in marine sediments of different grain size fractions, viz., medium sand (710 μm), fine sand (250 μm), and clay (PTEs were measured in the different size fractions of sediment using inductively coupled plasma mass spectrophotometer. The order of accumulation of all PTEs in the three fractions was ranked as Zn > Cu > Pb > As > Co > Mo and in the three locations as Rameswaram > Palk Bay > Pamban. The concentration of PTEs in Palk Bay and Rameswaram coast was significantly different (P PTEs in the coastal regions of GoM signifies the need to monitor the coast regularly using suitable monitoring tools such as sediments to prevent further damage to the marine ecosystem.

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

    Science.gov (United States)

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

    2003-01-01

    The nature of Re-platinum-group element (PGE; Pt, Pd, Ir, Os, Ru) transport in the marine environment was investigated by means of marine sediments at and across the Cretaceous-Tertiary boundary (KTB) at two hemipelagic sites in Europe and two pelagic sites in the North and South Pacific. A traverse across the KTB in the South Pacific pelagic clay core found elevated levels of Re, Pt, Ir, Os, and Ru, each of which is approximately symmetrically distributed over a distance of approx. 1.8 m across the KTB. The Re-PGE abundance patterns are fractionated from chondritic relative abundances: Ru, Pt, Pd, and Re contents are slightly subchondritic relative to Ir, and Os is depleted by approx. 95% relative to chondritic Ir proportions. A similar depletion in Os (approx. 90%) was found in a sample of the pelagic KTB in the North Pacific, but it is enriched in Ru, Pt, Pd, and Re relative to Ir. The two hemipelagic KTB clays have near-chondritic abundance patterns. The approx. 1.8-m-wide Re-PGE peak in the pelagic South Pacific section cannot be reconciled with the fallout of a single impactor, indicating that postdepositional redistribution has occurred. The elemental profiles appear to fit diffusion profiles, although bioturbation could have also played a role. If diffusion had occurred over approx. 65 Ma, the effective diffusivities are approx. 10(exp -13)sq cm/s, much smaller than that of soluble cations in pore waters (approx. 10(exp -5) sq cm/s). The coupling of Re and the PGEs during redistribution indicates that postdepositional processes did not significantly fractionate their relative abundances. If redistribution was caused by diffusion, then the effective diffusivities are the same. Fractionation of Os from Ir during the KTB interval must therefore have occurred during aqueous transport in the marine environment. Distinctly subchondritic Os/Ir ratios throughout the Cenozoic in the South Pacific core further suggest that fractionation of Os from Ir in the marine

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

    Science.gov (United States)

    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 prevailing terminal electron-accepting process in anoxic incubations of surface sediments, and even the addition of acetate stimulated neither iron nor sulfate reduction. The three geographically distinct sediments harbored surprisingly similar communities of acetate-utilizing manganese-reducing bacteria: 16S rRNA of members of the genera Colwellia and Arcobacter and of novel genera within the Oceanospirillaceae and Alteromonadales were detected in heavy RNA-SIP fractions from these three sediments. Most probable number (MPN) analysis yielded up to 106 acetate-utilizing manganese-reducing cells cm−3 in Gullmar Fjord sediment. A 16S rRNA gene clone library that was established from the highest MPN dilutions was dominated by sequences of Colwellia and Arcobacter species and members of the Oceanospirillaceae, supporting the obtained RNA-SIP results. In conclusion, these findings strongly suggest that (i) acetate-dependent manganese reduction in manganese oxide-rich sediments is catalyzed by members of taxa (Arcobacter, Colwellia and Oceanospirillaceae) previously not known to possess this physiological function, (ii) similar acetate-utilizing manganese reducers thrive in geographically distinct regions and (iii) the identified manganese reducers differ greatly from the extensively explored iron reducers in marine sediments. PMID:22572639

  18. In situ anaerobic degradation of petroleum alkanes in marine sediments: preliminary results; Degradation anaerobie d'alcanes petroliers dans un sediment marin: resultats preliminaires

    Energy Technology Data Exchange (ETDEWEB)

    Massias, D. [Centre National de la Recherche Scientifique (CNRS) UMR 6535, Lab. d' Oceanographie et de Biogeochimie, 13 - Marseille (France); Grossi, V.; Bertrand, J.C. [Centre National de la Recherche Scientifique (CNRS) UMR 6535, Lab. d' Oceanographie et de Biogeochimie, Faculte des Sciences de Luminy, 13 - Marseille (France)

    2003-05-01

    The degradation of acyclic petroleum hydrocarbons was studied during a 24-month experiment in Mediterranean coastal sediments (Gulf of Fos). Sediment cores entirely contaminated with oil (Arabian Light Crude Oil) were incubated in situ. The use of conservative tracers of sediment's particles reworking (luminophors) allowed the distinction of the reworked layer from the anoxic deeper sediments. Using the 17{alpha},21{beta}C{sub 30} hopane (C{sub 30}H) as an inert internal reference, we could demonstrate that, after 24 months of experiment, acyclic petroleum hydrocarbons can be degraded under natural anaerobic conditions. The reactivity of individual alkanes appeared to depend on their chemical structure. (authors)

  19. Action Spectra of Microalgal Photosynthesis and Depth Distribution of Spectral Scalar Irradiance in a Coastal Marine Sediment of Limfjorden, Denmark

    DEFF Research Database (Denmark)

    PLOUG, H.; LASSEN, C.; JØRGENSEN, BB

    1993-01-01

    The role of complementary spectral utilization of light for the zonation of different groups of oxygenic phototrophic organisms in sediments was studied. The marine sediment was covered by a dense population of diatoms with an underlying population of cyanobacteria. Action spectra for photosynthe......The role of complementary spectral utilization of light for the zonation of different groups of oxygenic phototrophic organisms in sediments was studied. The marine sediment was covered by a dense population of diatoms with an underlying population of cyanobacteria. Action spectra....... a and carotenoids being the major photosynthetic pigments. The action spectrum of the cyanobacteria showed photosynthesis maxima at the absorption regions of Chl. a and phycocyanin. The measured depth distribution of spectral scalar irradiance and the action spectra of diatoms and cyanobacteria were used...... to calculate the spectral quality for photosynthesis of the 400-700 nm light to which the two populations were exposed. This spectral quality was compared to that of the light incident on the sediment surface. Due to preferential extinction of wavelengths, at which their photosynthetically active pigments had...

  20. Measurement and modeling of polychlorinated biphenyl bioaccumulation from sediment for the marine polychaete neanthes arenaceodentata and response to sorbent amendment

    Science.gov (United States)

    Janssen, E.M.-L.; Croteau, M.-N.; Luoma, S.N.; Luthy, R.G.

    2010-01-01

    Bioaccumulation rates of polychlorinated biphenyls (PCBs) for the marine polychaete Neanthes arenaceodentata were characterized, including PCB uptake rates from water and sediment, and the effect of sorbent amendment to the sediment on PCB bioavailability, organism growth, and lipid content. Physiological parameters were incorporated into a biodynamic model to predict contaminant uptake. The results indicate rapid PCB uptake from contaminated sediment and significant organism growth dilution during time-series exposure studies. PCB uptake from the aqueous phase accounted for less than 3% of the total uptake for this deposit-feeder. Proportional increase of gut residence time and assimilation efficiency as a consequence of the organism's growth was assessed by PCB uptake and a reactor theory model of gut architecture. Pulse-chase feeding and multilabeled stable isotope tracing techniques proved high sediment ingestion rates (i.e., 6?10 times of dry body weight per day) indicating that such deposit-feeders are promising biological indicators for sediment risk assessment. Activated carbon amendment reduced PCB uptake by 95% in laboratory experiments with no observed adverse growth effects on the marine polychaete. Biodynamic modeling explained the observed PCB body burdens for N. arenaceodentata, with and without sorbent amendment. ?? 2009 American Chemical Society.

  1. Acoustics of marine sediment under compaction: binary grain-size model and viscoelastic extension of Biot's theory.

    Science.gov (United States)

    Leurer, Klaus C; Brown, Colin

    2008-04-01

    This paper presents a model of acoustic wave propagation in unconsolidated marine sediment, including compaction, using a concept of a simplified sediment structure, modeled as a binary grain-size sphere pack. Compressional- and shear-wave velocities and attenuation follow from a combination of Biot's model, used as the general framework, and two viscoelastic extensions resulting in complex grain and frame moduli, respectively. An effective-grain model accounts for the viscoelasticity arising from local fluid flow in expandable clay minerals in clay-bearing sediments. A viscoelastic-contact model describes local fluid flow at the grain contacts. Porosity, density, and the structural Biot parameters (permeability, pore size, structure factor) as a function of pressure follow from the binary model, so that the remaining input parameters to the acoustic model consist solely of the mass fractions and the known mechanical properties of each constituent (e.g., carbonates, sand, clay, and expandable clay) of the sediment, effective pressure, or depth, and the environmental parameters (water depth, salinity, temperature). Velocity and attenuation as a function of pressure from the model are in good agreement with data on coarse- and fine-grained unconsolidated marine sediments.

  2. Evaluation of Near-Surface Gases in Marine Sediments to Assess Subsurface Petroleum Gas Generation and Entrapment

    Directory of Open Access Journals (Sweden)

    Michael A. Abrams

    2017-05-01

    Full Text Available Gases contained within near-surface marine sediments can be derived from multiple sources: shallow microbial activity, thermal cracking of organic matter and inorganic materials, or magmatic-mantle degassing. Each origin will display a distinctive hydrocarbon and non-hydrocarbon composition as well as compound-specific isotope signature and thus the interpretation of origin should be relatively straightforward. Unfortunately, this is not always the case due to in situ microbial alteration, non-equilibrium phase partitioning, mixing, and fractionation related to the gas extraction method. Sediment gases can reside in the interstitial spaces, bound to mineral or organic surfaces and/or entrapped in carbonate inclusions. The interstitial sediment gases are contained within the sediment pore space, either dissolved in the pore waters (solute or as free (vapour gas. The bound gases are believed to be attached to organic and/or mineral surfaces, entrapped in structured water or entrapped in authigenic carbonate inclusions. The purpose of this paper is to provide a review of the gas types found within shallow marine sediments and examine issues related to gas sampling and extraction. In addition, the paper will discuss how to recognise mixing, alteration and fractionation issues to best interpret the seabed geochemical results and determine gas origin to assess subsurface petroleum gas generation and entrapment.

  3. 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.

  4. 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

  5. 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.

  6. Tracing the Paleo sulfate-methane transition zones and H2S seepage events in marine sediments: An application of C-S-Mo systematics

    Digital Repository Service at National Institute of Oceanography (India)

    Peketi, A.; Mazumdar, A.; Joshi, R.K.; Patil, D.J.; Srinivas, P.L.; Dayal, A.M.

    Microbially mediated anaerobic oxidation of methane (AOM) coupled with sulfate consumption within the sulfate methane transition zone (SMTZ) in marine sediments is a widely recorded biogeochemical reaction and has profound influence...

  7. 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....

  8. 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

  9. A synthesis of marine sediment core δ13C data over the last 150 000 years

    Directory of Open Access Journals (Sweden)

    R. E. M. Rickaby

    2010-10-01

    Full Text Available The isotopic composition of carbon, δ13C, in seawater is used in reconstructions of ocean circulation, marine productivity, air-sea gas exchange, and biosphere carbon storage. Here, a synthesis of δ13C measurements taken from foraminifera in marine sediment cores over the last 150 000 years is presented. The dataset comprises previously published and unpublished data from benthic and planktonic records throughout the global ocean. Data are placed on a common δ18O age scale suitable for examining orbital timescale variability but not millennial events, which are removed by a 10 ka filter. Error estimates account for the resolution and scatter of the original data, and uncertainty in the relationship between δ13C of calcite and of dissolved inorganic carbon (DIC in seawater. This will assist comparison with δ13C of DIC output from models, which can be further improved using model outputs such as temperature, DIC concentration, and alkalinity to improve estimates of fractionation during calcite formation. High global deep ocean δ13C, indicating isotopically heavy carbon, is obtained during Marine Isotope Stages (MIS 1, 3, 5a, c and e, and low δ13C during MIS 2, 4 and 6, which are temperature minima, with larger amplitude variability in the Atlantic Ocean than the Pacific Ocean. This is likely to result from changes in biosphere carbon storage, modulated by changes in ocean circulation, productivity, and air-sea gas exchange. The North Atlantic vertical δ13C gradient is greater during temperature minima than temperature maxima, attributed to changes in the spatial extent of Atlantic source waters. There are insufficient data from shallower than 2500 m to obtain a coherent pattern in other ocean basins. The data synthesis indicates that basin-scale δ13C during the last interglacial (MIS 5e is not clearly distinguishable from the Holocene (MIS 1 or from MIS 5a and 5c, despite significant differences in ice volume and atmospheric CO2

  10. The impact of military activities on the concentration of mercury in soils of military training grounds and marine sediments

    OpenAIRE

    G?bka, Karolina; Be?dowski, Jacek; Be?dowska, Magdalena

    2016-01-01

    Military activities have been conducted on land and at sea. Both during conflicts and in peace time, some regions served as a military training ground which included firing positions and bunkers. Mercury fulminate has been used in ammunition primers and detonators. Certain amount of ammunition was dumped into the Baltic Sea after the Second World War. Because of corroded containers, mercury can be released into the marine environment. The soil and sediment samples were taken from military tra...

  11. Phylogenetic Diversity and Biological Activity of Actinobacteria Isolated from the Chukchi Shelf Marine Sediments in the Arctic Ocean

    OpenAIRE

    Meng Yuan; Yong Yu; Hui-Rong Li; Ning Dong; Xiao-Hua Zhang

    2014-01-01

    Marine environments are a rich source of Actinobacteria and have the potential to produce a wide variety of biologically active secondary metabolites. In this study, we used four selective isolation media to culture Actinobacteria from the sediments collected from the Chukchi Shelf in the Arctic Ocean. A total of 73 actinobacterial strains were isolated. Based on repetitive DNA fingerprinting analysis, we selected 30 representatives for partial characterization according to their phylogenetic...

  12. Bioprospecting from Marine Sediments of New Brunswick, Canada: Exploring the Relationship between Total Bacterial Diversity and Actinobacteria Diversity

    OpenAIRE

    Katherine Duncan; Bradley Haltli; Gill, Krista A.; Kerr, Russell G.

    2014-01-01

    Actinomycetes are an important resource for the discovery of natural products with therapeutic properties. Bioprospecting for actinomycetes typically proceeds without a priori knowledge of the bacterial diversity present in sampled habitats. In this study, we endeavored to determine if overall bacterial diversity in marine sediments, as determined by 16S rDNA amplicon pyrosequencing, could be correlated with culturable actinomycete diversity, and thus serve as a powerful tool in guiding futu...

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

    Directory of Open Access Journals (Sweden)

    Alison L Spongberg

    2004-12-01

    Full Text Available Twenty-nine marine sediment samples collected from 1996 through 2002 from the Golfo Dulce embayment of Costa Rica were analyzed for PCB concentrations. The Esquinas River and Rincon Bay in the northern and western part of the gulf had relatively low overall concentrations of PCBs, with no samples having greater than 2.1 µg/g dw sediment. The Port of Golfito had the highest overall concentrations, ranging up to 15.7 µg/g dw sediment. These samples were also dominated by higher chlorinated congeners. Samples from the deeper (>100m waters in the northern part of the gulf, as well as within the sediment plume from the Rio Coto Colorado had intermediate values. Within the Rio Coto Colorado sediment plume the concentrations did decrease with increasing depth and the congeners showed a shift towards less chlorinated congeners with depth. However, the deep northern basin had some of the highest PCB concentrations and the shift towards less chlorinated congeners was not apparent or significant. Whether the anoxic conditions that exist in the deep waters are capable of initiating dechlorination is still unknown. Overall, the data from Golfo Dulce show moderate PCB contamination, despite the pristine nature of the gulf and surrounding landsUn total de 29 muestras de sedimentos recolectadas de 1996 a 2002 en el Golfo Dulce, Costa Rica fueron analizadas determinar las concentraciones de bifenilos policlorinados (PCBs. La Bahía de Rincón y el Río Esquinas en la parte noroeste del Golfo tienen concentraciones relativamente bajas de PCBs, con ninguna muestras superando los 2.1 ug/ dw (peso seco de sedimento. El puerto de Golfito tuvo las mayores concentraciones hasta un máximo de 15.7 ug/g dw de sedimento. Estas muestras también estuvieron dominadas por los congéneres más clorinados. Las muestras de los sedimentos profundos (>100 m de las aguas de la parte norte del Golfo, así como las de la estela del Río Coto Colorado, tienen concentraciones

  14. Nitrogen and phosphorus treatment of marine wastewater by a laboratory-scale sequencing batch reactor with eco-friendly marine high-efficiency sediment.

    Science.gov (United States)

    Cho, Seonghyeon; Kim, Jinsoo; Kim, Sungchul; Lee, Sang-Seob

    2017-06-22

    We screened and identified a NH3-N-removing bacterial strain, Bacillus sp. KGN1, and a [Formula: see text] removing strain, Vibrio sp. KGP1, from 960 indigenous marine isolates from seawater and marine sediment from Tongyeong, South Korea. We developed eco-friendly high-efficiency marine sludge (eco-HEMS), and inoculated these marine bacterial strains into the marine sediment. A laboratory-scale sequencing batch reactor (SBR) system using the eco-HEMS for marine wastewater from land-based fish farms improved the treatment performance as indicated by 88.2% removal efficiency (RE) of total nitrogen (initial: 5.6 mg/L) and 90.6% RE of total phosphorus (initial: 1.2 mg/L) under the optimal operation conditions (food and microorganism (F/M) ratio, 0.35 g SCODCr/g mixed liquor volatile suspended solids (MLVSS)·d; dissolved oxygen (DO) 1.0 ± 0.2 mg/L; hydraulic retention time (HRT), 6.6 h; solids retention time (SRT), 12 d). The following kinetic parameters were obtained: cell yield (Y), 0.29 g MLVSS/g SCODCr; specific growth rate (µ), 0.06 d(-1); specific nitrification rate (SNR), 0.49 mg NH3-N/g MLVSS·h; specific denitrification rate (SDNR), 0.005 mg [Formula: see text]/g MLVSS·h; specific phosphorus uptake rate (SPUR), 0.12 mg [Formula: see text]/g MLVSS·h. The nitrogen- and phosphorus-removing bacterial strains comprised 18.4% of distribution rate in the microbial community of eco-HEMS under the optimal operation conditions. Therefore, eco-HEMS effectively removed nitrogen and phosphorus from highly saline marine wastewater from land-based fish farms with improving SNR, SDNR, and SPUR values in more diverse microbial communities. DO: dissolved oxygen; Eco-HEMS: eco-friendly high efficiency marine sludge; F/M: food and microorganism ratio; HRT: hydraulic retention time; ML(V)SS: mixed liquor (volatile) suspended solids; NCBI: National Center for Biotechnology Information; ND: not determined; qPCR: quantitative real-time polymerase chain

  15. 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.

    Advances Vol. 2(1) January 2009 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) Khare N., Chaturvedi S.K. 1... regions. Keywords: Tsunami, impact, sediment transportation, foraminifera, microbenthos, indicator, Andaman, Indian Ocean. Introduction Coastal marine environments are inherently sensitive to climate changes. Consequences of climate changes in coastal...

  16. 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.

  17. Offshore drilling effects in Brazilian SE marine sediments: a meta-analytical approach.

    Science.gov (United States)

    Dore, Marina Pereira; Farias, Cássia; Hamacher, Cláudia

    2017-01-01

    The exploration and production of oil and gas reserves often result to drill cutting accumulations on the seafloor adjacent to drill locations. In this study, the detection of drilling influence on marine sediments was performed by meta-analytical comparison between data from pre- and post-drilling surveys undertaken in offshore Campos Basin, southeast of Brazil. Besides this overall appraisal on the geochemical variables, a multivariate assessment, considering only the post-drilling data, was performed. Among the variables, fines content, carbonates, total organic carbon, barium, chromium, copper, iron, manganese, nickel, lead, vanadium, zinc, and total petroleum hydrocarbons, only barium, copper, and hydrocarbons were related to drilling impacts. In relation to the point of discharge, relative elevated levels in the post-drilling campaigns were observed preferentially up to 500 m in the northeast and southwest directions, associated to the Brazil Current-predominant direction. Other distributed concentrations in the surroundings seem to indicate the dilution and dispersion of drilling waste promoted by meteoceanographic factors.

  18. Decreased stability of methane hydrates in marine sediments owing to phase-boundary roughness.

    Science.gov (United States)

    Wood, W T; Gettrust, J F; Chapman, N R; Spence, G D; Hyndman, R D

    2002-12-12

    Below water depths of about 300 metres, pressure and temperature conditions cause methane to form ice-like crystals of methane hydrate. Marine deposits of methane hydrate are estimated to be large, amassing about 10,000 gigatonnes of carbon, and are thought to be important to global change and seafloor stability, as well as representing a potentially exploitable energy resource. The extent of these deposits can usually be inferred from seismic imaging, in which the base of the methane hydrate stability zone is frequently identifiable as a smooth reflector that runs parallel to the sea floor. Here, using high-resolution seismic sections of seafloor sediments in the Cascadia margin off the coast of Vancouver Island, Canada, we observe lateral variations in the base of the hydrate stability zone, including gas-rich vertical intrusions into the hydrate stability zone. We suggest that these vertical intrusions are associated with upward flow of warmer fluids. Therefore, where seafloor fluid expulsion and methane hydrate deposits coincide, the base of the hydrate stability zone might exhibit significant roughness and increased surface area. Increased area implies that significantly more methane hydrate lies close to being unstable and hence closer to dissociation in the event of a lowering of pressure due to sea-level fall.

  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. 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.

  1. 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.

  2. Microbes in deep marine sediments viewed through amplicon sequencing and metagenomics

    Science.gov (United States)

    Biddle, J.; Leon, Z. R.; Russell, J. A., III; Martino, A. J.

    2016-12-01

    Nearly twenty percent of microbial biomass on Earth can be found in the marine subsurface. The majority of this is concentrated on continental margins, which have been investigated by scientific drilling. On the Costa Rica Margin, Iberian Margin and Peru Margins, sediment samples have been investigated through DNA extraction followed by amplicon and metagenomic sequencing. Overall samples show a high degree of microbial diversity, including many lineages of newly defined groups. In this talk, metagenome assembled genomes of unusual lineages will be presented, including their relationships to shallower relatives. From Costa Rica, in particular, we have retrieved deep relatives of Lokiarchaeota and Thorarchaeota, as well as other deeply branching archaeal relatives. We discuss their genome similarities to both other archaea and eukaryotes. From the Iberian Margin, relatives of Atribacteria and Aerophobetes will be discussed. Finally, we will detail the knowledge lost or gained depending on whether samples are studied via amplicon sequencing or total metagenomics, as studies in other environments have shown that up to 15% of microbial diversity is ignored when samples are studied via amplicon sequencing alone.

  3. Bacillus maritimus sp. nov., a novel member of the genus Bacillus isolated from marine sediment.

    Science.gov (United States)

    Pal, Deepika; Mathan Kumar, Rajendran; Kaur, Navjot; Kumar, Narender; Kaur, Gurwinder; Singh, Nitin Kumar; Krishnamurthi, Srinivasan; Mayilraj, Shanmugam

    2017-01-01

    The taxonomic position of a Gram-stain-positive, endospore-forming bacterium, strain KS16-9T, isolated from a marine sediment sample collected from Kovalam, Kanyakumari coastal region of the Indian Ocean, India, was analysed by a polyphasic approach. Strain KS16-9T had typical phenotypic characteristics and chemotaxonomic features (menaquinones, fatty acids and lipids) that were consistent with the genus Bacillus. omparative analysis of the 16S rRNA gene sequence of the strain with previously published Bacillus type strains confirmed that it belongs to the genus Bacillus and is moderately related to Bacillus persicus B48T (98.42 % similarity), followed by Bacillus foraminis CV53T (97.67 %) and Bacillus rigiliprofundi (97.61 %). Other species in the genus Bacillusshared Bacillus, for which the name Bacillus maritimus sp. nov. is proposed. The type strain is KS16-9T (=MTCC 12305T=DSM 100413T=KCTC 33834T).

  4. Biodegradation of PAHs by Burkholderia sp. VITRSB1 Isolated from Marine Sediments

    Directory of Open Access Journals (Sweden)

    T. Revathy

    2015-01-01

    Full Text Available The polycyclic aromatic hydrocarbons (PAHs pollution to the environment is a major threat to the living organisms, and hence the degradation of these PAHs is necessary. Studies on PAHs degrading bacteria have focussed on terrestrial microbes and the potential of marine derived microbes is undermined. Herein we report the isolation and characterization of PAHs degrading Burkholderia sp. from lagoon sediments collected at the Southern coast of India. The strain was Gram negative, rod-shaped, motile, and ∼2–5 μm in length. Based on the phylogenetic data the strain was identified as Burkholderia and designated as VITRSB1. Initial PAHs degradation ability of the strain was assessed using basal salt medium supplemented with diesel, kerosene, toluene, aniline, naphthalene, and phenol. The strain was found to be effectively degrading kerosene, diesel, toluene, and aniline even at higher concentration (1%. However, naphthalene and aniline were degraded only at lower concentration (0.1% and phenol, camphor, and DAP inhibited the growth of the strain. Furthermore, the degraded end products of the PAHs were determined using FTIR. Notably, none of the end products were found to be toxic to the biosphere. Our results indicate that the isolated Burkholderia sp. could be a prospective candidate for the effective degradation of selective PAHs.

  5. Paleoclimatic record of the last 18 ka cal BP in marine sediments from Pescadero Basin, southern Gulf of California

    Science.gov (United States)

    Escorza-Reyes, M.; Perez-Cruz, L. L.; Fucugauchi, J. U.

    2013-05-01

    In this study are presented the geochemical and magnetic records with a multi-decadal resolution from a marine sequence, in order to reconstruct the oceanographic and climatic conditions during the past 18 ka in the southern Gulf of California. A gravity core DIPAL III-T2 was recovered in the eastern part of Pescadero Basin, at 577 m depth, in the Pacific Intermediate Water (PIW) and Oxygen Minimum Zone (OMZ), aboard the R/V "El Puma" of the National University of Mexico (UNAM). The core is 263 cm long. Concentrations of chemical elements were measured every cm using an X-ray fluorescence analyzer (Niton XL3t 900S) and magnetic susceptibility measurements were taken every 0.5 cm with a Bartington Susceptibilimeter with MS2B sensor. Chronology is based on seven AMS radiocarbon dates calibrated and reservoir age corrected. According to the age model, the marine sequence comprises the last 18 ka and sedimentation rates range from ~0.05 mm/yr to ~0.29 mm/yr, increasing upward. The marine sequence consists of massive and homogeneous sediments from bottom to 200 cm, and from there to the top a well defined laminated structure is observed. Sediments are composed mainly of terrigenous (~80%) and in less amount silica and calcium carbonate biogenic remains (~15%). A sharp difference in concentrations of five elements (Ti, Zr, Ca, Ba and V), also observed in magnetic susceptibility measurements and sedimentary structures, marks four intervals of different oceanographic and atmospheric conditions in the southeastern Gulf of California, being the glacial-interglacial transition one of the most evident. Vanadium concentrations downcore show low values during Pleistocene, where sediments are massive, and high values during the Holocene, where laminated sediments are preserved. These conditions suggest a decrease in oxygen-levels in the water column during Holocene, probably due to productivity increase in surface waters related to intensification of NW winds, evidenced by high

  6. 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.

  7. An improved method for quantitatively measuring the sequences of total organic carbon and black carbon in marine sediment cores

    Science.gov (United States)

    Xu, Xiaoming; Zhu, Qing; Zhou, Qianzhi; Liu, Jinzhong; Yuan, Jianping; Wang, Jianghai

    2017-04-01

    Understanding global carbon cycle is critical to uncover the mechanisms of global warming and remediate its adverse effects on human activities. Organic carbon in marine sediments is an indispensable part of the global carbon reservoir in global carbon cycling. Evaluating such a reservoir calls for quantitative studies of marine carbon burial, which closely depend on quantifying total organic carbon and black carbon in marine sediment cores and subsequently on obtaining their high-resolution temporal sequences. However, the conventional methods for detecting the contents of total organic carbon or black carbon cannot resolve the following specific difficulties, i.e., (1) a very limited amount of each subsample versus the diverse analytical items, (2) a low and fluctuating recovery rate of total organic carbon or black carbon versus the reproducibility of carbon data, and (3) a large number of subsamples versus the rapid batch measurements. In this work, (i) adopting the customized disposable ceramic crucibles with the micropore-controlled ability, (ii) developing self-made or customized facilities for the procedures of acidification and chemothermal oxidization, and (iii) optimizing procedures and carbon-sulfur analyzer, we have built a novel Wang-Xu-Yuan method (the WXY method) for measuring the contents of total organic carbon or black carbon in marine sediment cores, which includes the procedures of pretreatment, weighing, acidification, chemothermal oxidation and quantification; and can fully meet the requirements of establishing their highresolution temporal sequences, whatever in the recovery, experimental efficiency, accuracy and reliability of the measurements, and homogeneity of samples. In particular, the usage of disposable ceramic crucibles leads to evidently simplify the experimental scenario, which further results in the very high recovery rates for total organic carbon and black carbon. This new technique may provide a significant support for

  8. Evaluation of a bioassays battery for ecotoxicological screening of marine sediments from Ionian Sea (Mediterranea Sea, Southern Italy).

    Science.gov (United States)

    Prato, Ermelinda; Parlapiano, Isabella; Biandolino, Francesca

    2012-09-01

    Sediments are an ecologically important component of the aquatic environment and may play a key role in mediating the exchange of contaminants between particulate, dissolved, and biological phases. For a comprehensive assessment of potential sediment toxicity, the use of a single species may not detect toxicant with a specific mode of action. Therefore it is advisable to carry out ecotoxicological tests on a base-set of taxa utilizing test species belonging to different trophic levels. This paper describes the ecotoxicological evaluation of marine sediments from seven sites of Mar Piccolo estuary (Southern, Italy), four of them were located in the first inlet and three in the second inlet of Mar Piccolo estuary. Sediment samples from a site in Taranto Gulf were used as control sediment. Dunaliella tertiolecta, Tigriopus fulvus, Mytilus galloprovincialis, and Corophium insidiosum, were employed to identify the quality of sediments. The integration of biological tests results showed that all sampling sites located in the first inlet of Mar Piccolo were identified as toxic, according to all tests, while the sites of second inlet were found not toxic. The results obtained in this study indicate that the use of a battery of biological tests have important implications for risk assessment in estuarine e coastal waters.

  9. Paleosols can promote root growth of recent vegetation - a case study from the sandy soil-sediment sequence Rakt, the Netherlands

    Science.gov (United States)

    Gocke, Martina I.; Kessler, Fabian; van Mourik, Jan M.; Jansen, Boris; Wiesenberg, Guido L. B.

    2016-10-01

    Soil studies commonly comprise the uppermost meter for tracing, e.g., soil development. However, the maximum rooting depth of various plants significantly exceeds this depth. We hypothesized that deeper parts of the soil, soil parent material and especially paleosols provide beneficial conditions in terms of, e.g., nutrient contents, thus supporting their utilization and exploitation by deep roots. We aimed to decipher the different phases of soil formation in Dutch drift sands and cover sands. The study site is located at Bedafse Bergen (southeastern Netherlands) in a 200-year-old oak stand. A recent Podzol developed on drift sand covering a Plaggic Anthrosol that was piled up on a relict Podzol on Late Glacial eolian cover sand. Root-free soil and sediment samples, collected in 10-15 cm depth increments, were subjected to a multi-proxy physical and geochemical approach. The Plaggic Anthrosol revealed low bulk density and high phosphorous and organic carbon contents, whereas the relict Podzol was characterized by high iron and aluminum contents. Frequencies of fine (diameter ≤ 2 mm) and medium roots (2-5 mm) were determined on horizontal levels and the profile wall for a detailed pseudo-three-dimensional insight. On horizontal levels, living roots were most abundant in the uppermost part of the relict Podzol with ca. 4450 and 220 m-2, significantly exceeding topsoil root abundances. Roots of oak trees thus benefited from the favorable growth conditions in the nutrient-rich Plaggic Anthrosol, whereas increased compactness and high aluminum contents of the relict Podzol caused a strong decrease of roots. The approach demonstrated the benefit of comprehensive root investigation to support interpretation of soil profiles, as fine roots can be significantly underestimated when quantified at the profile wall. The possible rooting of soil parent material and paleosols long after their burial confirmed recent studies on the potential influence of rooting to overprint

  10. NMR-based metabolomics for the environmental assessment of Kaohsiung Harbor sediments exemplified by a marine amphipod (Hyalella azteca).

    Science.gov (United States)

    Chiu, K H; Dong, C D; Chen, C F; Tsai, M L; Ju, Y R; Chen, T M; Chen, C W

    2017-03-03

    Inflow of wastewater from upstream causes a large flux of pollutants to enter Kaohsiung Harbor in Taiwan daily. To reveal the ecological risk posed by Kaohsiung Harbor sediments, an ecological metabolomic approach was employed to investigate environmental factors pertinent to the physiological regulation of the marine amphipod Hyalella azteca. The amphipods were exposed to sediments collected from different stream inlets of the Love River (LR), Canon River (CR), Jen-Gen River (JR), and Salt River (SR). Harbor entrance 1 (E1) was selected as a reference site. After 10-day exposure, metabolomic analysis of the Hyalella azteca revealed differences between two groups: {E1, LR, CR} and {JR, SR}. The metabolic pathways identified in the two groups of amphipods were significantly different. The results demonstrated that NMR-based metabolomics can be effectively used to characterize metabolic response related to sediment from polluted areas. Copyright © 2017. Published by Elsevier Ltd.

  11. The use of fluvial and marine sediments in the formulation of roller compacted concrete for use in pavements.

    Science.gov (United States)

    Zdiri, M; Abriakb, N E; Ben Ouezdoua, M; Neji, J

    2009-07-01

    In the manufacture of Roller Compacted Concrete (RCC) used for pavement materials, various types of aggregates are used, such as crushed and rolled limestone or siliceous aggregates. The main objective is always to reach the maximum compactness to achieve higher mechanical performances. In the present work, fluvial and marine sediments, resulting from the dredging of harbours and rivers, were introduced as aggregates in the preparation of RCC for pavement construction, with a view to improving the mechanical strength of the RCC. This study included a granulometric, mineralogical and chemical characterization of the aggregates. The work also contains a mechanical characterization of the resulting material. The objective of the study was to find a resistant RCC, by developing materials such as sediments that are often classified as a waste and where their storage is harmful to the environment. The mechanical strengths obtained showed the profitability of using a Roller Compacted Concrete containing sediments.

  12. Bioprospecting from marine sediments of New Brunswick, Canada: exploring the relationship between total bacterial diversity and actinobacteria diversity.

    Science.gov (United States)

    Duncan, Katherine; Haltli, Bradley; Gill, Krista A; Kerr, Russell G

    2014-02-13

    Actinomycetes are an important resource for the discovery of natural products with therapeutic properties. Bioprospecting for actinomycetes typically proceeds without a priori knowledge of the bacterial diversity present in sampled habitats. In this study, we endeavored to determine if overall bacterial diversity in marine sediments, as determined by 16S rDNA amplicon pyrosequencing, could be correlated with culturable actinomycete diversity, and thus serve as a powerful tool in guiding future bioprospecting efforts. Overall bacterial diversity was investigated in eight marine sediments from four sites in New Brunswick, Canada, resulting in over 44,000 high quality sequences (x = 5610 per sample). Analysis revealed all sites exhibited significant diversity (H' = 5.4 to 6.7). Furthermore, statistical analysis of species level bacterial communities (D = 0.03) indicated community composition varied according to site and was strongly influenced by sediment physiochemical composition. In contrast, cultured actinomycetes (n = 466, 98.3% Streptomyces) were ubiquitously distributed among all sites and distribution was not influenced by sediment composition, suggesting that the biogeography of culturable actinomycetes does not correlate with overall bacterial diversity in the samples examined. These actinomycetes provide a resource for future secondary metabolite discovery, as exemplified by the antimicrobial activity observed from preliminary investigation.

  13. Bioprospecting from Marine Sediments of New Brunswick, Canada: Exploring the Relationship between Total Bacterial Diversity and Actinobacteria Diversity

    Science.gov (United States)

    Duncan, Katherine; Haltli, Bradley; Gill, Krista A.; Kerr, Russell G.

    2014-01-01

    Actinomycetes are an important resource for the discovery of natural products with therapeutic properties. Bioprospecting for actinomycetes typically proceeds without a priori knowledge of the bacterial diversity present in sampled habitats. In this study, we endeavored to determine if overall bacterial diversity in marine sediments, as determined by 16S rDNA amplicon pyrosequencing, could be correlated with culturable actinomycete diversity, and thus serve as a powerful tool in guiding future bioprospecting efforts. Overall bacterial diversity was investigated in eight marine sediments from four sites in New Brunswick, Canada, resulting in over 44,000 high quality sequences (x = 5610 per sample). Analysis revealed all sites exhibited significant diversity (H’ = 5.4 to 6.7). Furthermore, statistical analysis of species level bacterial communities (D = 0.03) indicated community composition varied according to site and was strongly influenced by sediment physiochemical composition. In contrast, cultured actinomycetes (n = 466, 98.3% Streptomyces) were ubiquitously distributed among all sites and distribution was not influenced by sediment composition, suggesting that the biogeography of culturable actinomycetes does not correlate with overall bacterial diversity in the samples examined. These actinomycetes provide a resource for future secondary metabolite discovery, as exemplified by the antimicrobial activity observed from preliminary investigation. PMID:24531187

  14. Bioprospecting from Marine Sediments of New Brunswick, Canada: Exploring the Relationship between Total Bacterial Diversity and Actinobacteria Diversity

    Directory of Open Access Journals (Sweden)

    Katherine Duncan

    2014-02-01

    Full Text Available Actinomycetes are an important resource for the discovery of natural products with therapeutic properties. Bioprospecting for actinomycetes typically proceeds without a priori knowledge of the bacterial diversity present in sampled habitats. In this study, we endeavored to determine if overall bacterial diversity in marine sediments, as determined by 16S rDNA amplicon pyrosequencing, could be correlated with culturable actinomycete diversity, and thus serve as a powerful tool in guiding future bioprospecting efforts. Overall bacterial diversity was investigated in eight marine sediments from four sites in New Brunswick, Canada, resulting in over 44,000 high quality sequences (x̄ = 5610 per sample. Analysis revealed all sites exhibited significant diversity (H’ = 5.4 to 6.7. Furthermore, statistical analysis of species level bacterial communities (D = 0.03 indicated community composition varied according to site and was strongly influenced by sediment physiochemical composition. In contrast, cultured actinomycetes (n = 466, 98.3% Streptomyces were ubiquitously distributed among all sites and distribution was not influenced by sediment composition, suggesting that the biogeography of culturable actinomycetes does not correlate with overall bacterial diversity in the samples examined. These actinomycetes provide a resource for future secondary metabolite discovery, as exemplified by the antimicrobial activity observed from preliminary investigation.

  15. Exploring Actinobacteria assemblages in coastal marine sediments under contrasted Human influences in the West Istria Sea, Croatia.

    Science.gov (United States)

    Duran, Robert; Bielen, Ana; Paradžik, Tina; Gassie, Claire; Pustijanac, Emina; Cagnon, Christine; Hamer, Bojan; Vujaklija, Dušica

    2015-10-01

    The exploration of marine Actinobacteria has as major challenge to answer basic questions of microbial ecology that, in turn, will provide useful information to exploit Actinobacteria metabolisms in biotechnological processes. The ecological functions performed by Actinobacteria in marine sediments are still unclear and belongs to the most burning basic questions. The comparison of Actinobacteria communities inhabiting marine sediments that are under the influence of different contamination types will provide valuable information in the adaptation capacities of Actinobacteria to colonize specific ecological niche. In the present study, the characterization of different Actinobacteria assemblages according to contamination type revealed the ecological importance of Actinobacteria for maintaining both general biogeochemical functions through a "core" Actinobacteria community and specific roles associated with the presence of contaminants. Indeed, the results allowed to distinguish Actinobacteria genera and species operational taxonomic units (OTUs) able to cope with the presence of either (i) As, (ii) metals Ni, Fe, V, Cr, and Mn, or (iii) polycyclic aromatic hydrocarbons (PAHs) and toxic metals (Hg, Cd, Cu, Pb, and Zn). Such observations highlighted the metabolic capacities of Actinobacteria and their potential that should be taken into consideration and advantage during the implementation of bioremediation processes in marine ecosystems.

  16. Assessing Bioavailability of DDT and Metabolites in Marine Sediments using Solid-Phase Microextraction with Performance Reference Compounds

    Science.gov (United States)

    Bao, Lian-Jun; Jia, Fang; Crago, J.; Zeng, Eddy Y.; Schlenk, D.; Gan, Jay

    2014-01-01

    Solid-phase microextraction (SPME) has often been used to estimate the freely dissolved concentration (Cfree) of organic contaminants in sediments. A significant limitation in the application of SPME for Cfree measurement is the requirement for attaining equilibrium partition, which is often difficult for strongly hydrophobic compounds such as DDT. A method was developed using SPME with stable isotope-labeled analogues as performance reference compounds (PRCs) to measure Cfree of DDT and metabolites (DDTs) in marine sediments. Six 13C-labeled or deuterated PRCs were impregnated into polydimethylsiloxane (PDMS) fiber before use. Desorption of PRCs from PDMS fibers and absorption of DDTs from sediment were isotropic in a range of sediments evaluated ex situ under well-mixed conditions. When applied to a historically contaminated marine sediment from a Superfund site, the PRC-SPME method yielded Cfree values identical to those found by using a conventional equilibrium SPME approach (Eq-SPME), wherease the time for mixing was reduced from 9 d to only 9 h. The PRC-SPME method was further evaluated against bioaccumulation of DDTs by Neanthes arenaceodentata in the contaminated sediment with or without amendment of activated carbon or sand. Strong correlations were consistently found between the derived equilibrium concentrations on the fiber and lipid-normalized tissue residues for DDTs in the worms. Results from the present study clearly demonstrated the feasibility of coupling PRCs with SPME sampling to greatly shorten sampling time, thus affording much improved flexibility in the use of SPME for bioavailability evaluation. Environ Toxicol Chem 2013;32:1946–1953. PMID:23661411

  17. Butyltin compounds and their relation with organic matter in marine sediments from San Vicente Bay-Chile.

    Science.gov (United States)

    Pinochet, Hugo; Tessini, Catherine; Bravo, Manuel; Quiroz, Waldo; De Gregori, Ida

    2009-08-01

    Tributyltin and its degradation products, mono-and dibutyltin have been determined in sediments collected in some representative sites in San Vicente Bay, Chile. The organic matter contents of sediments and water collected simultaneously from the same sampling sites were also determined. High levels of total organic carbon were found in sediments, especially in those from the northern part of the bay (1.80-8.87%). Good correlations were found between total organic carbon and the oxidizable and refractory carbon fractions. Among the butyltin species determined, TBT presented the highest levels, ranging from 14 to 1,560 ng Sn g(-1) dry weight. Concentration ratios of TBT to DBT ranged between 1.33 and 3.10, showing a high degree of contamination in sediments of this Chilean bay. All data obtained were analysed by the chemometric method of principal components analysis. A strong correlation was found between TBT and DBT concentrations in sediments, the different organic matter contents in sediments and water. In marine organisms only TBT was detected, containing the filterer organism Semele solida higher level than Perumytilus purpuratus and Pyura chilensis (220, 150 and 120 ng Sn g(-1) dry weight, respectively). For the alga Rodoficea iridae the TBT concentration was 60 ng Sn g(-1) dw. Comparatively, these values are higher than those reported for the same kind of marine organisms worldwide. The different samples from San Vicente Bay were found to be contaminated by TBT. This contamination can be attributed to the different anthropogenic activities taking place in the bay.

  18. 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.

  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. 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

  1. Regime shift in sandy beach microbial communities following Deepwater Horizon oil spill remediation efforts.

    Science.gov (United States)

    Engel, Annette Summers; Gupta, Axita A

    2014-01-01

    Sandy beaches support a wide variety of underappreciated biodiversity that is critical to coastal ecosystems. Prior to the 2010 Deepwater Horizon oil spill, the diversity and function of supratidal beach sediment microbial communities along Gulf of Mexico coastlines were not well understood. As such, it was unclear if microbial community compositional changes would occur following exposure to beached oil, if indigenous communities could biodegrade oil, or how cleanup efforts, such as sand washing and sediment redistribution, would impact microbial ecosystem resiliency. Transects perpendicular to the shoreline were sampled from public beaches on Grand Isle, Louisiana, and Dauphin Island, Alabama, over one year. Prior to oil coming onshore, elevated levels of bacteria associated with fecal contamination were detected (e.g., Enterobacteriales and Campylobacterales). Over time, significant shifts within major phyla were identified (e.g., Proteobacteria, Firmicutes, Actinobacteria) and fecal indicator groups were replaced by taxa affiliated with open-ocean and marine systems (e.g., Oceanospirillales, Rhodospirillales, and Rhodobacterales). These new bacterial groups included putative hydrocarbon degraders, similar to those identified near the oil plume offshore. Shifts in the microbial community composition strongly correlated to more poorly sorted sediment and grain size distributional changes. Natural oceanographic processes could not account for the disrupted sediment, especially from the backshore well above the maximum high-tide levels recorded at these sites. Sand washing and tilling occurred on both open beaches from August through at least December 2010, which were mechanisms that could replace fecal indicator groups with open-ocean groups. Consequently, remediation efforts meant to return beaches to pre-spill compositions caused a regime shift that may have added potential ecosystem function, like hydrocarbon degradation, to the sediment. Future research will

  2. Regime shift in sandy beach microbial communities following Deepwater Horizon oil spill remediation efforts.

    Directory of Open Access Journals (Sweden)

    Annette Summers Engel

    Full Text Available Sandy beaches support a wide variety of underappreciated biodiversity that is critical to coastal ecosystems. Prior to the 2010 Deepwater Horizon oil spill, the diversity and function of supratidal beach sediment microbial communities along Gulf of Mexico coastlines were not well understood. As such, it was unclear if microbial community compositional changes would occur following exposure to beached oil, if indigenous communities could biodegrade oil, or how cleanup efforts, such as sand washing and sediment redistribution, would impact microbial ecosystem resiliency. Transects perpendicular to the shoreline were sampled from public beaches on Grand Isle, Louisiana, and Dauphin Island, Alabama, over one year. Prior to oil coming onshore, elevated levels of bacteria associated with fecal contamination were detected (e.g., Enterobacteriales and Campylobacterales. Over time, significant shifts within major phyla were identified (e.g., Proteobacteria, Firmicutes, Actinobacteria and fecal indicator groups were replaced by taxa affiliated with open-ocean and marine systems (e.g., Oceanospirillales, Rhodospirillales, and Rhodobacterales. These new bacterial groups included putative hydrocarbon degraders, similar to those identified near the oil plume offshore. Shifts in the microbial community composition strongly correlated to more poorly sorted sediment and grain size distributional changes. Natural oceanographic processes could not account for the disrupted sediment, especially from the backshore well above the maximum high-tide levels recorded at these sites. Sand washing and tilling occurred on both open beaches from August through at least December 2010, which were mechanisms that could replace fecal indicator groups with open-ocean groups. Consequently, remediation efforts meant to return beaches to pre-spill compositions caused a regime shift that may have added potential ecosystem function, like hydrocarbon degradation, to the sediment

  3. Textural analysis of marine sediments at the USGS Woods Hole Science Center; methodology and data on DVD

    Science.gov (United States)

    Poppe, Lawrence J.; Williams, S. Jeffress; Paskevich, Valerie F.

    2006-01-01

    Marine sediments off the eastern United States vary markedly in texture (i.e., the size, shape, composition, and arrangement of their grains) due to a complex geologic history. For descriptive purposes, however, it is typically most useful to classify these sediments according to their grain-size distributions. In 1962, the U.S. Geological Survey began a program to study the marine geology of the continental margin off the Atlantic coast of the United States. As part of this program and numerous subsequent projects, thousands of sediment grab samples and cores were collected and analyzed for grain size at the Woods Hole Science Center. USGS Open-File Report 2005-1001 (Poppe et al., 2005), available on DVD and online, describes the field methods used to collect marine sediment samples as well as the laboratory methods used to determine and characterize grain-size distributions, and presents these data in several formats that can be readily employed by interested parties. The report is divided into three sections. The first section discusses procedures and contains pictures of the equipment, analytical flow diagrams, video clips with voice commentary, classification schemes, useful forms and compiled and uncompiled versions of the data-acquisition and data-processing software with documentation. The second section contains the grain-size data for more than 23,000 analyses in two “flat-file” formats, a data dictionary, and color-coded browse maps. The third section provides a GIS data catalog of the available point, interpretive, and baseline data layers, with FGDC-compliant metadata to help users visualize the textural information in a geographic context.

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

    Directory of Open Access Journals (Sweden)

    Danielle eMonteverde

    2015-05-01

    Full Text Available 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 putative B1 producers, yet these environments have received little attention as a possible source of B1 to the overlying water column. Here we report the first dissolved pore water profiles of B1 measured in cores collected in two consecutive years from Santa Monica Basin, CA. Vitamin B1 concentrations were fairly consistent between the two years ranging from 30 pM up to 770 pM. A consistent maximum at ~5 cm sediment depth covaried with dissolved concentrations of iron. Pore water concentrations were higher than water column levels and represented some of the highest known environmental concentrations of B1 measured to date, (over two times higher than maximum water column concentrations suggesting increased rates of cellular production and release within the sediments. A one dimensional diffusion-transport model applied to the B1 profile was used to estimate a diffusive benthic flux of ~0.7 nmol m 2 d-1. This is an estimated flux across the sediment-water interface in a deep sea basin; if similar magnitude B-vitamin fluxes occur in shallow coastal waters, benthic input could prove to be a significant B1-source to the water column and may play an important role in supplying this organic growth factor to auxotrophic primary producers.

  5. Dynamic transition of chemolithotrophic sulfur-oxidizing bacteria in response to amendment with nitrate in deposited marine sediments

    Directory of Open Access Journals (Sweden)

    Tomo eAoyagi

    2015-05-01

    Full Text Available Although environmental stimuli are known to affect the structure and function of microbial communities, their impact on the metabolic network of microorganisms has not been well investigated. Here, geochemical analyses, high-throughput sequencing of 16S rRNA genes and transcripts, and isolation of potentially relevant bacteria were carried out to elucidate the anaerobic respiration processes stimulated by nitrate (20 mM amendment of marine sediments. Marine sediments deposited by the Great East Japan Earthquake in 2011 were incubated anaerobically in the dark at 25°C for 5 days. Nitrate in slurry water decreased gradually for 2 days, then more rapidly until its complete depletion at day 5; production of N2O followed the same pattern. From day 2 to 5, the sulfate concentration increased and the sulfur content in solid-phase sediments significantly decreased. These results indicated that denitrification and sulfur oxidation occurred simultaneously. Illumina sequencing revealed the proliferation of known sulfur oxidizers, i.e., Sulfurimonas spp. and Chromatiales bacteria, which accounted for approximately 43.5% and 14.8% of the total population at day 5, respectively. They also expressed 16S rRNA to a considerable extent, whereas the other microorganisms, e.g., iron(III reducers and methanogens, became metabolically active at the end of the incubation. Extinction dilution culture in a basal-salts medium supplemented with sulfur compounds and nitrate successfully isolated the predominant sulfur oxidizers: Sulfurimonas sp. strain HDS01 and Thioalkalispira sp. strain HDS22. Their 16S rRNA genes showed 95.2−96.7% sequence similarity to the closest cultured relatives and they grew chemolithotrophically on nitrate and sulfur. Novel sulfur-oxidizing bacteria were thus directly involved in carbon fixation under nitrate-reducing conditions, activating anaerobic respiration processes and the reorganization of microbial communities in the deposited marine

  6. Dynamic transition of chemolithotrophic sulfur-oxidizing bacteria in response to amendment with nitrate in deposited marine sediments.

    Science.gov (United States)

    Aoyagi, Tomo; Kimura, Makoto; Yamada, Namiha; Navarro, Ronald R; Itoh, Hideomi; Ogata, Atsushi; Sakoda, Akiyoshi; Katayama, Yoko; Takasaki, Mitsuru; Hori, Tomoyuki

    2015-01-01

    Although environmental stimuli are known to affect the structure and function of microbial communities, their impact on the metabolic network of microorganisms has not been well investigated. Here, geochemical analyses, high-throughput sequencing of 16S rRNA genes and transcripts, and isolation of potentially relevant bacteria were carried out to elucidate the anaerobic respiration processes stimulated by nitrate (20 mM) amendment of marine sediments. Marine sediments deposited by the Great East Japan Earthquake in 2011 were incubated anaerobically in the dark at 25∘C for 5 days. Nitrate in slurry water decreased gradually for 2 days, then more rapidly until its complete depletion at day 5; production of N2O followed the same pattern. From day 2 to 5, the sulfate concentration significantly increased and the sulfur content in solid-phase sediments significantly decreased. These results indicated that denitrification and sulfur oxidation occurred simultaneously. Illumina sequencing revealed the proliferation of known sulfur oxidizers, i.e., Sulfurimonas sp. and Chromatiales bacteria, which accounted for approximately 43.5% and 14.8% of the total population at day 5, respectively. These oxidizers also expressed 16S rRNA to a considerable extent, whereas the other microorganisms, e.g., iron(III) reducers and methanogens, became metabolically active at the end of the incubation. Extinction dilution culture in a basal-salts medium supplemented with sulfur compounds and nitrate successfully isolated the predominant sulfur oxidizers: Sulfurimonas sp. strain HDS01 and Thioalkalispira sp. strain HDS22. Their 16S rRNA genes showed 95.2-96.7% sequence similarity to the closest cultured relatives and they grew chemolithotrophically on nitrate and sulfur. Novel sulfur-oxidizing bacteria were thus directly involved in carbon fixation under nitrate-reducing conditions, activating anaerobic respiration processes and the reorganization of microbial communities in the deposited

  7. Marine sediments and palaeoclimatic variations since the Late Pleistocene: An overview for the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Hashimi, N.H.

    A large number of surfacial and sub-surface sediments from the Arabian Sea have been studied to enhance our understanding of palaeoclimatic variations over the Indian region. Bsically the surficial sediments have been studied for their living...

  8. Carbonate mineralogy and faunal relationship in tropical shallow water marine sediments: Cape Comorin, India

    Digital Repository Service at National Institute of Oceanography (India)

    Hashimi, N.H.; Nair, R.R.; Kidwai, R.M.; Rao, V.P.

    The carbonate mineralogy of Recent sediments from the western and eastern continental shelves around Cape Comorin off the southern tip of India was determined by X-ray diffraction analyses. The results show that in the sediments where benthic...

  9. Distribution of short chain chlorinated paraffins in marine sediments of the East China Sea: influencing factors, transport and implications.

    Science.gov (United States)

    Zeng, Lixi; Zhao, Zongshan; Li, Huijuan; Wang, Thanh; Liu, Qian; Xiao, Ke; Du, Yuguo; Wang, Yawei; Jiang, Guibin

    2012-09-18

    Short chain chlorinated paraffins (SCCPs) are high production volume chemicals in China and found to be widely present in the environment. In this study, fifty-one surface sediments and two sediment cores were collected from the East China Sea to study their occurrence, distribution patterns and potential transport in the marginal sea. SCCPs were found in all surface sediments and ranged from 5.8 to 64.8 ng/g (dry weight, d.w.) with an average value of 25.9 ng/g d.w. A general decreasing trend with distance from the coast was observed, but the highest value was found in a distal mud area far away from the land. The C10 homologue was the most predominant carbon chain group, followed by C11, C12, and C13 homologue groups. Significant linear relationship was found between total organic carbon (TOC) and total SCCP concentrations (R(2) = 0.51, p < 0.05). Spatial distributions and correlation analysis indicated that TOC, riverine input, ocean current, and atmospheric deposition played an important role in controlling SCCP accumulation in marine sediments. Vertical profiles of sediment cores showed that SCCP concentrations decreased from surface to the depth of 36 cm, and then slightly increased again with depth, which showed a significant positive correlation with TOC and chlorine contents (Cl%). The results suggest that SCCPs are being regionally or globally distributed by long-range atmospheric or ocean current transport.

  10. Quaternary forest and climate history of Hokkaido, Japan, from marine sediments

    Science.gov (United States)

    Igarashi, Yaeko

    Pollen data from Quaternary marine sediments deposited in central Hokkaido, northern Japan provide insight into northeast Asian vegetation and climatic changes over the last few million years. During the Early Pleistocene, coniferous forest, dominated by Picea and Cryptomeria japonica, and taiga composed of Larix and Picea developed under cool/wet and cold/dry climates, respectively. Strong climatic contrasts are inferred from Late Pleistocene interglacial and glacial pollen assemblages which precede the last glacial cycle. In the former, cool temperate broad-leaf forest, mainly composed of Fagus, reflects a warmer and wetter climate than now. In the latter, taiga similar to that now found in northern Sakhalin apparently flourished in Hokkaido. The composition of pollen assemblages correlated with Oxygen Isotope Stage 5, changed from cool temperate forest of Quercus, Ulmus and Juglans (Substage 5e), to Picea-Larix taiga (Substage 5d), cool temperate forest of Quercus and Ulmus (Substage 5c) and Picea-Abies forest (Substage 5b). Compared with present conditions, climate during Stage 5 in northern Japan apparently fluctuated from warmer/wetter to colder/drier. Taiga composed of Picea, Pinus and Larix indicating colder/dry conditions during Stage 4, was replaced by Picea-Abies forest and Picea-Larix taiga in Stage 3, suggesting relatively cool and cold/dry environments. Taiga and mixed forest with taiga and cool temperate components characterize Stage 2. Holocene forests with Juglans-Betula and Quercus-Juglans were succeeded by Picea and Abies during the early Holocene warm interval ˜7000 BP. Subsequently, Quercus-Ulmus and Abies-Alnus assemblages reflect climatic deterioration. 'Pan-mixed' forest has been developed in Hokkaido since 2000 BP.

  11. Enterococcus faecium ST17 from Coastal Marine Sediment Carrying Transferable Multidrug Resistance Plasmids.

    Science.gov (United States)

    Morroni, Gianluca; Di Cesare, Andrea; Di Sante, Laura; Brenciani, Andrea; Vignaroli, Carla; Pasquaroli, Sonia; Giovanetti, Eleonora; Sabatino, Raffaella; Rossi, Luigia; Magnani, Mauro; Biavasco, Francesca

    2016-10-01

    The multidrug-resistant Enterococcus faecium 17i48, sequence type 17, from marine sediment, carrying erm(B), tet(M), and tet(L) genes, was analyzed for the presence of antibiotic resistance plasmids and for the ability to transfer resistance genes. The strain was found to harbor the replicon type (repA) of pRE25, pRUM, pHTβ, and the axe-txe toxin-antitoxin (TA) system. In mating experiments, tet(M) and tet(L) were cotransferred with the repApRE25, whereas erm(B) was consistently cotransferred with the axe-txe and repApRUM, suggesting that tetracycline and erythromycin resistance genes were carried on different elements both transferable by conjugation, likely via pHTβ-mediated mobilization. Hybridization and PCR mapping demonstrated that tet(M) and tet(L) were located in tandem on a pDO1-like plasmid that also carried the repApRE25, whereas erm(B) was carried by a pRUM-like plasmid. Sequencing of the latter plasmid showed a high nucleotide identity with pRUM and the presence of cat, aadE, sat4, and a complete aphA resistance genes. These findings show that the genetic features of E. faecium 17i48 are consistent with a hospital-adapted clone and suggest that antibiotic resistance may spread in the environment, also in the absence of antibiotic pressure, due to TA system plasmid maintenance.

  12. Is Ice-Rafted Sediment in a North Pole Marine Record Evidence for Perennial Sea-ice Cover?

    Science.gov (United States)

    Tremblay, L.B.; Schmidt, G.A.; Pfirman, S.; Newton, R.; DeRepentigny, P.

    2015-01-01

    Ice-rafted sediments of Eurasian and North American origin are found consistently in the upper part (13 Ma BP to present) of the Arctic Coring Expedition (ACEX) ocean core from the Lomonosov Ridge, near the North Pole (approximately 88 degrees N). Based on modern sea-ice drift trajectories and speeds, this has been taken as evidence of the presence of a perennial sea-ice cover in the Arctic Ocean from the middle Miocene onwards. However, other high latitude land and marine records indicate a long-term trend towards cooling broken by periods of extensive warming suggestive of a seasonally ice-free Arctic between the Miocene and the present. We use a coupled sea-ice slab-ocean model including sediment transport tracers to map the spatial distribution of ice-rafted deposits in the Arctic Ocean. We use 6 hourly wind forcing and surface heat fluxes for two different climates: one with a perennial sea-ice cover similar to that of the present day and one with seasonally ice-free conditions, similar to that simulated in future projections. Model results confirm that in the present-day climate, sea ice takes more than 1 year to transport sediment from all its peripheral seas to the North Pole. However, in a warmer climate, sea-ice speeds are significantly faster (for the same wind forcing) and can deposit sediments of Laptev, East Siberian and perhaps also Beaufort Sea origin at the North Pole. This is primarily because of the fact that sea-ice interactions are much weaker with a thinner ice cover and there is less resistance to drift. We conclude that the presence of ice-rafted sediment of Eurasian and North American origin at the North Pole does not imply a perennial sea-ice cover in the Arctic Ocean, reconciling the ACEX ocean core data with other land and marine records.

  13. 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

  14. Biogeographical distribution and diversity of microbes in methane hydrate-bearing deep marine sediments on the Pacific Ocean Margin.

    Science.gov (United States)

    Inagaki, Fumio; Nunoura, Takuro; Nakagawa, Satoshi; Teske, Andreas; Lever, Mark; Lauer, Antje; Suzuki, Masae; Takai, Ken; Delwiche, Mark; Colwell, Frederick S; Nealson, Kenneth H; Horikoshi, Koki; D'Hondt, Steven; Jørgensen, Bo B

    2006-02-21

    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 (approximately 1 kbp) from the two geographically separated subseafloor environments. Archaea of the uncultivated Deep-Sea Archaeal Group were consistently the dominant phylotype in sediments associated with methane hydrate. Sediment cores lacking methane hydrates displayed few or no Deep-Sea Archaeal Group phylotypes. Bacterial communities in the methane hydrate-bearing sediments were dominated by members of the JS1 group, Planctomycetes, and Chloroflexi. Results from cluster and principal component analyses, which include previously reported data from the West and East Pacific Margins, suggest that, for these locations in the Pacific Ocean, prokaryotic communities from methane hydrate-bearing sediment cores are distinct from those in hydrate-free cores. The recognition of which microbial groups prevail under distinctive subseafloor environments is a significant step toward determining the role these communities play in Earth's essential biogeochemical processes.

  15. Determination of tributyltin in marine sediment and waters by pressurised solvent extraction and liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Nichols, David S; Jordan, Timothy B; Kerr, Neil

    2014-05-01

    In this study, tributyltin (TBT) was extracted from marine sediment matrix with the use of pressurised solvent extraction (PSE), which uses high-temperature and -pressure conditions to increase extraction efficiency. The analyte was chromatographically resolved using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) system with a pentafluorophenyl (PFP) column and a methanol/aqueous formic acid mobile phase gradient, and was detected by MS/MS as product fragments after collisionally induced dissociation (CID) of the cationic parent molecule. This study represents the first application of PSE extraction combined with LC-MS/MS analysis for the determination of TBT in sediments. The method has been validated according to the International Organisation for Standardisation (ISO) 17025:2001 and affords automated extraction of sediment samples with high-sensitivity analysis. The full method limit of detection was established as 1.25 ng Sn g(-1) with an instrument detection limit of 0.01 ng Sn g(-1). The chromatographic procedure may also be applied for the direct analysis of water matrices without the need for sample manipulation, and therefore represents a combined analytical approach for the monitoring of TBT contamination in marine or estuarine ecosystems.

  16. Potential for heavy metal (copper and zinc) removal from contaminated marine sediments using microalgae and light emitting diodes

    Science.gov (United States)

    Kwon, Hyeong Kyu; Jeon, Jin Young; Oh, Seok Jin

    2017-03-01

    The effects of monochromatic (blue, yellow and red LED) and mixed wavelengths (fluorescent lamp) on the adsorption and absorption of Cu and Zn by Phaeodactylum tricornutum, Nitzschia sp., Skeletonema sp., and Chlorella vulgaris were investigated. In addition, we confirmed the potential of microalgae for phytoremediation of these heavy metals from contaminated marine sediment by using microcosm experiments that incorporated LEDs and semipermeable membrane (SPM) tube containing microalgae. Among the four microalgae, C. vulgaris grown under red LED exhibited the highest Cu and Zn removal with values of 17.5 × 10-15 g Cu/cell and 38.3 × 10-15 g Zn/cell, respectively. Thus, C. vulgaris could be a useful species for phytoremediation. In the microcosm experiments with SPM containing C. vulgaris, the highest Cu and Zn removal from sediment and interstitial water showed under red LED. Therefore, phytoremediation using LED and SPM tube containing microalgae could be utilized as an eco-friendly technique for remediating contaminated marine sediment.

  17. An Evaluation of Marine Sediments in Terms of their usability in the Brick Industry: Case Study Port of Koper

    Directory of Open Access Journals (Sweden)

    Patrik Baksa

    2018-03-01

    Full Text Available A dredging process is essential for the development of harbours and ports, allowing the functional daily operation of the port. The management of dredged material represents a worldwide challenge, especially considering unwanted deposition of material. Because of their chemical, petrographic, mineralogical and homogeneity composition, marine sediments could represent an appropriate raw material for the brick industry, particularly for the production of clay blocks, roofing and ceramic tiles. In this study dredged material from Port of Koper was tested for such use, thus various analyses were carried out in order to determine if the dredged material is environmentally friendly and suitable for use in the brick industry. These included: chemical analysis, mineralogical analysis, particle size analysis, chloride content analysis and tests of firing in a gradient furnace. Furthermore, tests of mechanical properties, as well as tests of the frost-resistance of the samples were carried out. On the basis of the primary analyses and samples prepared in a laboratory, it was confirmed that marine sediments from the Port of Koper, without any additives are only conditionally suitable as a source material for producing brick products, because without additives they exhibit too much shrinkage on drying and firing, as well as high water absorption, this can be improved by the incorporation of suitable additives, for example, virgin clay or other suitable waste material. The approach described herewith can also be followed to assess sediments from other ports and rivers regarding its potential use in clay brick sector.

  18. Culturable diversity and antimicrobial activity of Actinobacteria from marine sediments in Valparaíso bay, Chile

    Science.gov (United States)

    Claverías, Fernanda P.; Undabarrena, Agustina; González, Myriam; Seeger, Michael; Cámara, Beatriz

    2015-01-01

    Marine-derived Actinobacteria are a source of a broad variety of secondary metabolites with diverse biological activities, such as antibiotics and antitumorals; many of which have been developed for clinical use. Rare Actinobacteria represent an untapped source of new bioactive compounds that have been scarcely recognized. In this study, rare Actinobacteria from marine sediments were isolated from the Valparaíso bay, Chile, and their potential to produce antibacterial compounds was evaluated. Different culture conditions and selective media that select the growth of Actinobacteria were used leading to the isolation of 68 bacterial strains. Comparative analysis of the 16S rRNA gene sequences led to identifying isolates that belong to the phylum Actinobacteria with genetic affiliations to 17 genera: Aeromicrobium, Agrococcus, Arthrobacter, Brachybacterium, Corynebacterium, Dietzia, Flaviflexus, Gordonia, Isoptericola, Janibacter, Microbacterium, Mycobacterium, Ornithinimicrobium, Pseudonocardia, Rhodococcus, Streptomyces, and Tessaracoccus. Also, one isolate could not be consistently classified and formed a novel phylogenetic branch related to the Nocardiopsaceae family. The antimicrobial activity of these isolates was evaluated, demonstrating the capability of specific novel isolates to inhibit the growth of Gram-positive and Gram-negative bacteria. In conclusion, this study shows a rich biodiversity of culturable Actinobacteria, associated to marine sediments from Valparaíso bay, highlighting novel rare Actinobacteria, and their potential for the production of biologically active compounds. PMID:26284034

  19. Culturable diversity and antimicrobial activity of Actinobacteria from marine sediments in Valparaíso bay, Chile

    Directory of Open Access Journals (Sweden)

    Fernanda Paz Claverías

    2015-07-01

    Full Text Available Marine-derived Actinobacteria are a source of a broad variety of secondary metabolites with diverse biological activities, such as antibiotics and antitumorals; many of which have been developed for clinical use. Rare Actinobacteria represent an untapped source of new bioactive compounds that have been scarcely recognized. In this study, rare Actinobacteria from marine sediments were isolated from the Valparaíso bay, Chile, and their potential to produce antibacterial compounds was evaluated. Different culture conditions and selective media that select the growth of Actinobacteria were used leading to the isolation of 68 bacterial strains. Comparative analysis of the 16S rRNA gene sequences led to identifying isolates that belong to the phylum Actinobacteria with genetic affiliations to 17 genera: Aeromicrobium, Agrococcus, Arthrobacter, Brachybacterium, Corynebacterium, Dietzia, Flaviflexus, Gordonia, Isoptericola, Janibacter, Microbacterium, Mycobacterium, Ornithinimicrobium, Pseudonocardia, Rhodococcus, Streptomyces and Tessaracoccus. Also, one isolate could not be consistently classified and formed a novel phylogenetic branch related to the Nocardiopsaceae family. The antimicrobial activity of these isolates was evaluated, demonstrating the capability of specific novel isolates to inhibit the growth of Gram-positive and Gram-negative bacteria. In conclusion, this study shows a rich biodiversity of culturable Actinobacteria, associated to marine sediments from Valparaíso bay, highlighting novel rare Actinobacteria, and their potential for the production of biologically active compounds.

  20. Culturable diversity and antimicrobial activity of Actinobacteria from marine sediments in Valparaíso bay, Chile.

    Science.gov (United States)

    Claverías, Fernanda P; Undabarrena, Agustina; González, Myriam; Seeger, Michael; Cámara, Beatriz

    2015-01-01

    Marine-derived Actinobacteria are a source of a broad variety of secondary metabolites with diverse biological activities, such as antibiotics and antitumorals; many of which have been developed for clinical use. Rare Actinobacteria represent an untapped source of new bioactive compounds that have been scarcely recognized. In this study, rare Actinobacteria from marine sediments were isolated from the Valparaíso bay, Chile, and their potential to produce antibacterial compounds was evaluated. Different culture conditions and selective media that select the growth of Actinobacteria were used leading to the isolation of 68 bacterial strains. Comparative analysis of the 16S rRNA gene sequences led to identifying isolates that belong to the phylum Actinobacteria with genetic affiliations to 17 genera: Aeromicrobium, Agrococcus, Arthrobacter, Brachybacterium, Corynebacterium, Dietzia, Flaviflexus, Gordonia, Isoptericola, Janibacter, Microbacterium, Mycobacterium, Ornithinimicrobium, Pseudonocardia, Rhodococcus, Streptomyces, and Tessaracoccus. Also, one isolate could not be consistently classified and formed a novel phylogenetic branch related to the Nocardiopsaceae family. The antimicrobial activity of these isolates was evaluated, demonstrating the capability of specific novel isolates to inhibit the growth of Gram-positive and Gram-negative bacteria. In conclusion, this study shows a rich biodiversity of culturable Actinobacteria, associated to marine sediments from Valparaíso bay, highlighting novel rare Actinobacteria, and their potential for the production of biologically active compounds.

  1. Quantifying and overcoming bioturbation in marine sediment cores: dual 14C and δ18O analysis on single foraminifera

    Science.gov (United States)

    Lougheed, Bryan; Metcalfe, Brett; Wacker, Lukas

    2017-04-01

    Marine sediment cores used in palaeoceanography form the basis of our current understanding of past global climate and ocean chemistry. Precision and accuracy of geochronological control in these sediment cores are crucial in unravelling the timing of rapid shifts in palaeoclimate and, ultimately, the interdependency of global climate mechanisms and their causality. Aware of the problems associated with bioturbation (the mixing of ocean sediments by benthic organisms) palaeoceanographers generally aim to retrieve sediment cores from locations with high sediment accumulation rates, thus minimising the influence of bioturbation as much as possible. However, the practice of concentrating only on areas of the ocean floor with high sedimentation accumulation rates has the potential to introduce a geographical bias into our understanding of global palaeoclimate. For example, global time averaged sediment accumulation rates for the ocean floor (excluding continental margins) indicate that vast areas of the ocean floor have sediment accumulation rates less than the recommended minimum advised sediment accumulation rates of 10 cm/ka or greater. Whilst many studies have focussed on quantifying the impact of bioturbation on our understanding of the past, few have attempted to overcome the problems associated with bioturbation. Recent pioneering developments in 14C AMS at the Laboratory of Ion Beam Physics at ETH Zürich have led to the development of the Mini Carbon Dating System (MICADAS). This compact 14C AMS system can be coupled to a carbonate handling system, thus enabling the direct AMS measurement of gaseous samples, i.e. without graphitisation, allowing for the analysis of carbonate samples of <100 μg. Likewise, while earlier isotope ratio mass spectrometry (IRMS) technology required a minimum of 100 μg of carbonate to produce a successful δ18O measurement, more recent advances in IRMS technology have made routine measurements of as little as 5 μg possible

  2. Real-Time PCR Quantification and Diversity Analysis of the Functional Genes aprA and dsrA of Sulfate-Reducing Prokaryotes in Marine Sediments of the Peru Continental Margin and the Black Sea

    OpenAIRE

    Blazejak, Anna; Schippers, Axel

    2011-01-01

    Sulfate-reducing prokaryotes (SRP) are ubiquitous and quantitatively important members in many ecosystems, especially in marine sediments. However their abundance and diversity in subsurface marine sediments is poorly understood. In this study, the abundance and diversity of the functional genes for the enzymes adenosine 5′-phosphosulfate reductase (aprA) and dissimilatory sulfite reductase (dsrA) of SRP in marine sediments of the Peru continental margin and the Black Sea were analyzed, inclu...

  3. Carbonate Geochemistry of Marine Authigenic Carbonates and Host Sediments: Exploring Mineral Formation Pathways and Organic Preservation Potential in Modern Sediments

    Science.gov (United States)

    Smirnoff, M. N.; Loyd, S. J.

    2016-12-01

    Ancient authigenic dolomites (e.g., concretions) have been long studied in order to determine formation conditions and provide insight into shallow diagenetic environments. The formation of these dolomites is commonly attributed to the anaerobic microbial degradation of organic matter (a process that can increase the local pore water alkalinity), based on carbon isotope as well as other geochemical data. Authigenic dolomites also occur in modern, "still soft" sediments rich in organic matter. However, a comprehensive carbon isotopic characterization of these precipitates has yet to be conducted. Preliminary data show a wide range of δ13C values (about -11 to +12‰). Positive values that typify dolomites of the Gulf of California and the southwestern African margin indicate methanogenesis. Dolomites of the Peru margin and Cariaco Basin yield negative values that may represent a variety of organic matter degradation mechanisms. Regardless of specific mechanisms, organic matter degradation can promote authigenesis. Ultimately, mineralization encases primary sedimentary components and may act to preserve organic matter from subsequent degradation due to permeability reduction resulting from cementation. Concretionary carbonates have been found to preserve macro and micro fossils, metastable sedimentary grains, magnetic minerals, sedimentary structures, various specific organic compounds, and overmature organic matter exposed in outcrop. However, a similar protective relationship has not been demonstrated for disseminated, bulk organic matter in still-soft sediments. The study of these sediments 1) reveal the relationship between organic carbon degradation and authigenesis and 2) may provide insight into the potential of cementation to preserve organic matter during subsequent burial.

  4. Patterns and Processes in Marine Microeukaryotic Community Biogeography from Xiamen Coastal Waters and Intertidal Sediments, Southeast China

    Directory of Open Access Journals (Sweden)

    Weidong Chen

    2017-10-01

    Full Text Available Microeukaryotes play key roles in the structure and functioning of marine ecosystems. Little is known about the relative importance of the processes that drive planktonic and benthic microeukaryotic biogeography in subtropical offshore areas. This study compares the microeukaryotic community compositions (MCCs from offshore waters (n = 12 and intertidal sediments (n = 12 around Xiamen Island, southern China, using high-throughput sequencing of 18S rDNA. This work further quantifies the relative contributions of spatial and environmental variables on the distribution of marine MCCs (including total, dominant, rare and conditionally rare taxa. Our results showed that planktonic and benthic MCCs were significantly different, and the benthic richness (6627 OTUs was much higher than that for plankton (4044 OTUs with the same sequencing effort. Further, we found that benthic MCCs exhibited a significant distance-decay relationship, whereas the planktonic communities did not. After removing two unique sites (N2 and N3, however, 72% variation in planktonic community was explained well by stochastic processes. More importantly, both the environmental and spatial factors played significant roles in influencing the biogeography of total and dominant planktonic and benthic microeukaryotic communities, although their relative effects on these community variations were different. However, a high proportion of unexplained variation in the rare taxa (78.1–97.4% and conditionally rare taxa (49.0–81.0% indicated that more complex mechanisms may influence the assembly of the rare subcommunity. These results demonstrate that patterns and processes in marine microeukaryotic community assembly differ among the different habitats (coastal water vs. intertidal sediment and different communities (total, dominant, rare and conditionally rare microeukaryotes, and provide novel insight on the microeukaryotic biogeography and ecological mechanisms in coastal waters and

  5. Patterns and Processes in Marine Microeukaryotic Community Biogeography from Xiamen Coastal Waters and Intertidal Sediments, Southeast China.

    Science.gov (United States)

    Chen, Weidong; Pan, Yongbo; Yu, Lingyu; Yang, Jun; Zhang, Wenjing

    2017-01-01

    Microeukaryotes play key roles in the structure and functioning of marine ecosystems. Little is known about the relative importance of the processes that drive planktonic and benthic microeukaryotic biogeography in subtropical offshore areas. This study compares the microeukaryotic community compositions (MCCs) from offshore waters (n = 12) and intertidal sediments (n = 12) around Xiamen Island, southern China, using high-throughput sequencing of 18S rDNA. This work further quantifies the relative contributions of spatial and environmental variables on the distribution of marine MCCs (including total, dominant, rare and conditionally rare taxa). Our results showed that planktonic and benthic MCCs were significantly different, and the benthic richness (6627 OTUs) was much higher than that for plankton (4044 OTUs) with the same sequencing effort. Further, we found that benthic MCCs exhibited a significant distance-decay relationship, whereas the planktonic communities did not. After removing two unique sites (N2 and N3), however, 72% variation in planktonic community was explained well by stochastic processes. More importantly, both the environmental and spatial factors played significant roles in influencing the biogeography of total and dominant planktonic and benthic microeukaryotic communities, although their relative effects on these community variations were different. However, a high proportion of unexplained variation in the rare taxa (78.1-97.4%) and conditionally rare taxa (49.0-81.0%) indicated that more complex mechanisms may influence the assembly of the rare subcommunity. These results demonstrate that patterns and processes in marine microeukaryotic community assembly differ among the different habitats (coastal water vs. intertidal sediment) and different communities (total, dominant, rare and conditionally rare microeukaryotes), and provide novel insight on the microeukaryotic biogeography and ecological mechanisms in coastal waters and intertidal