Organic matter degradation in surface sediments of the Changjiang estuary: Evidence from amino acids.

PubMed

Wang, Kui; Chen, Jianfang; Jin, Haiyan; Li, Hongliang; Zhang, Weiyan

2018-05-12

Organic matter degradation is a key component of the processes of carbon preservation and burial in seafloor sediments. The aim of this study was to explore organic matter degradation state within the open-shelf Changjiang Estuary of the East China Sea, using an amino acids-based degradation index (DI) in conjunction with information about organic matter source (marine versus terrestrial), bottom water oxygenation state, and sediment grain size. The relative molar percentages of 17 individual amino acids (characterized using principal component analysis) in surface sediments indicate that organic matter is degraded to varying extents across the estuary seabed. Sediments with DI >0 (relatively labile) were found mostly within a coastal hypoxic area. Sediments of DI less than -1 (relatively refractory) were found near the Changjiang River mouth and the northern and southern parts of the central shelf. We consider DI to be a more reliable indicator of degradation than simple ratios of AAs. DI was inversely correlated with the proportion of terrestrial organic material (F t ) in the sediments, indicating that relatively fresh/labile organic matter was generally associated with marine sources. DI was significantly correlated with F t and bottom water apparent oxygen utilization (AOU bot ) together. The parameter DI and the (labile) amino acid tyrosine were highest in hypoxic areas, suggesting the presence of relatively fresh organic matter, probably due to a combination of marine-source inputs and better preservation of organic matter in the silt and clay sediments of these areas (as compared to sandy sediments). Less degraded organic matter with high amino acids was also favorable to benthic animals. Overall, sedimentary estuarine organic matter was least degraded in areas characterized by marine sources of organic matter, low-oxygen conditions, and fine-grained sediments. Copyright © 2018 Elsevier B.V. All rights reserved.

TESTING ACUTE TOXICITY OF CONTAMINATED SEDIMENT IN JINZHOU BAY WITH MARINE AMPHIPODS

EPA Science Inventory

Sediments in some areas of Jinzhou Bay are contaminated seriously by heavy metals and organic contaminants. To assess the biological effects of these compounds in the sediment, seven surface samples of sediment were collected at an interval of about 2km between sampling stations ...

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

PubMed Central

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

Distinct Bacterial Communities in Surficial Seafloor Sediments Following the 2010 Deepwater Horizon Blowout.

PubMed

Yang, Tingting; Speare, Kelly; McKay, Luke; MacGregor, Barbara J; Joye, Samantha B; Teske, Andreas

2016-01-01

A major fraction of the petroleum hydrocarbons discharged during the 2010 Macondo oil spill became associated with and sank to the seafloor as marine snow flocs. This sedimentation pulse induced the development of distinct bacterial communities. Between May 2010 and July 2011, full-length 16S rRNA gene clone libraries demonstrated bacterial community succession in oil-polluted sediment samples near the wellhead area. Libraries from early May 2010, before the sedimentation event, served as the baseline control. Freshly deposited oil-derived marine snow was collected on the surface of sediment cores in September 2010, and was characterized by abundantly detected members of the marine Roseobacter cluster within the Alphaproteobacteria. Samples collected in mid-October 2010 closest to the wellhead contained members of the sulfate-reducing, anaerobic bacterial families Desulfobacteraceae and Desulfobulbaceae within the Deltaproteobacteria, suggesting that the oil-derived sedimentation pulse triggered bacterial oxygen consumption and created patchy anaerobic microniches that favored sulfate-reducing bacteria. Phylotypes of the polycyclic aromatic hydrocarbon-degrading genus Cycloclasticus, previously found both in surface oil slicks and the deep hydrocarbon plume, were also found in oil-derived marine snow flocs sedimenting on the seafloor in September 2010, and in surficial sediments collected in October and November 2010, but not in any of the control samples. Due to the relative recalcitrance and stability of polycyclic aromatic compounds, Cycloclasticus represents the most persistent microbial marker of seafloor hydrocarbon deposition that we could identify in this dataset. The bacterial imprint of the DWH oil spill had diminished in late November 2010, when the bacterial communities in oil-impacted sediment samples collected near the Macondo wellhead began to resemble their pre-spill counterparts and spatial controls. Samples collected in summer of 2011 did not show a consistent bacterial community signature, suggesting that the bacterial community was no longer shaped by the DWH fallout of oil-derived marine snow, but instead by location-specific and seasonal factors.

Distinct Bacterial Communities in Surficial Seafloor Sediments Following the 2010 Deepwater Horizon Blowout

PubMed Central

Yang, Tingting; Speare, Kelly; McKay, Luke; MacGregor, Barbara J.; Joye, Samantha B.; Teske, Andreas

2016-01-01

A major fraction of the petroleum hydrocarbons discharged during the 2010 Macondo oil spill became associated with and sank to the seafloor as marine snow flocs. This sedimentation pulse induced the development of distinct bacterial communities. Between May 2010 and July 2011, full-length 16S rRNA gene clone libraries demonstrated bacterial community succession in oil-polluted sediment samples near the wellhead area. Libraries from early May 2010, before the sedimentation event, served as the baseline control. Freshly deposited oil-derived marine snow was collected on the surface of sediment cores in September 2010, and was characterized by abundantly detected members of the marine Roseobacter cluster within the Alphaproteobacteria. Samples collected in mid-October 2010 closest to the wellhead contained members of the sulfate-reducing, anaerobic bacterial families Desulfobacteraceae and Desulfobulbaceae within the Deltaproteobacteria, suggesting that the oil-derived sedimentation pulse triggered bacterial oxygen consumption and created patchy anaerobic microniches that favored sulfate-reducing bacteria. Phylotypes of the polycyclic aromatic hydrocarbon-degrading genus Cycloclasticus, previously found both in surface oil slicks and the deep hydrocarbon plume, were also found in oil-derived marine snow flocs sedimenting on the seafloor in September 2010, and in surficial sediments collected in October and November 2010, but not in any of the control samples. Due to the relative recalcitrance and stability of polycyclic aromatic compounds, Cycloclasticus represents the most persistent microbial marker of seafloor hydrocarbon deposition that we could identify in this dataset. The bacterial imprint of the DWH oil spill had diminished in late November 2010, when the bacterial communities in oil-impacted sediment samples collected near the Macondo wellhead began to resemble their pre-spill counterparts and spatial controls. Samples collected in summer of 2011 did not show a consistent bacterial community signature, suggesting that the bacterial community was no longer shaped by the DWH fallout of oil-derived marine snow, but instead by location-specific and seasonal factors. PMID:27679609

Potential Mechanisms for Microbial Energy Acquisition in Oxic Deep-Sea Sediments

PubMed Central

Heidelberg, John F.

2016-01-01

ABSTRACT The South Pacific Gyre (SPG) possesses the lowest rates of sedimentation, surface chlorophyll concentration, and primary productivity in the global oceans. As a direct result, deep-sea sediments are thin and contain small amounts of labile organic carbon. It was recently shown that the entire SPG sediment column is oxygenated and may be representative of up to a third of the global marine environment. To understand the microbial processes that contribute to the removal of the labile organic matter at the water-sediment interface, a sediment sample was collected and subjected to metagenomic sequencing and analyses. Analysis of nine partially reconstructed environmental genomes, which represent approximately one-third of the microbial community, revealed that the members of the SPG surface sediment microbial community are phylogenetically distinct from surface/upper-ocean organisms. These genomes represent a wide distribution of novel organisms, including deep-branching Alphaproteobacteria, two novel organisms within the Proteobacteria, and new members of the Nitrospirae, Nitrospinae, and candidate phylum NC10. These genomes contain evidence for microbially mediated metal (iron/manganese) oxidation and carbon fixation linked to nitrification. Additionally, despite hypothesized energy limitation, members of the SPG microbial community had motility and chemotaxis genes and possessed mechanisms for the degradation of high-molecular-weight organic matter. This study contributes to our understanding of the metabolic potential of microorganisms in deep-sea oligotrophic sediments and their impact on local carbon geochemistry. IMPORTANCE This research provides insight into the microbial metabolic potential of organisms inhabiting oxygenated deep-sea marine sediments. Current estimates suggest that these environments account for up to a third of the global marine sediment habitat. Nine novel deep-sea microbial genomes were reconstructed from a metagenomic data set and expand the limited number of environmental genomes from deep-sea sediment environments. This research provides phylogeny-linked insight into critical metabolisms, including carbon fixation associated with nitrification, which is assignable to members of the marine group 1 Thaumarchaeota, Nitrospinae, and Nitrospirae and neutrophilic metal (iron/manganese) oxidation assignable to a novel proteobacterium. PMID:27208118

Potential Mechanisms for Microbial Energy Acquisition in Oxic Deep-Sea Sediments.

PubMed

Tully, Benjamin J; Heidelberg, John F

2016-07-15

The South Pacific Gyre (SPG) possesses the lowest rates of sedimentation, surface chlorophyll concentration, and primary productivity in the global oceans. As a direct result, deep-sea sediments are thin and contain small amounts of labile organic carbon. It was recently shown that the entire SPG sediment column is oxygenated and may be representative of up to a third of the global marine environment. To understand the microbial processes that contribute to the removal of the labile organic matter at the water-sediment interface, a sediment sample was collected and subjected to metagenomic sequencing and analyses. Analysis of nine partially reconstructed environmental genomes, which represent approximately one-third of the microbial community, revealed that the members of the SPG surface sediment microbial community are phylogenetically distinct from surface/upper-ocean organisms. These genomes represent a wide distribution of novel organisms, including deep-branching Alphaproteobacteria, two novel organisms within the Proteobacteria, and new members of the Nitrospirae, Nitrospinae, and candidate phylum NC10. These genomes contain evidence for microbially mediated metal (iron/manganese) oxidation and carbon fixation linked to nitrification. Additionally, despite hypothesized energy limitation, members of the SPG microbial community had motility and chemotaxis genes and possessed mechanisms for the degradation of high-molecular-weight organic matter. This study contributes to our understanding of the metabolic potential of microorganisms in deep-sea oligotrophic sediments and their impact on local carbon geochemistry. This research provides insight into the microbial metabolic potential of organisms inhabiting oxygenated deep-sea marine sediments. Current estimates suggest that these environments account for up to a third of the global marine sediment habitat. Nine novel deep-sea microbial genomes were reconstructed from a metagenomic data set and expand the limited number of environmental genomes from deep-sea sediment environments. This research provides phylogeny-linked insight into critical metabolisms, including carbon fixation associated with nitrification, which is assignable to members of the marine group 1 Thaumarchaeota, Nitrospinae, and Nitrospirae and neutrophilic metal (iron/manganese) oxidation assignable to a novel proteobacterium. Copyright © 2016 Tully and Heidelberg.

Transport of branched tetraether lipids from the Tagus River basin to the coastal ocean of the Portuguese margin: Consequences for the interpretation of the MBT'/CBT paleothermometer

NASA Astrophysics Data System (ADS)

Zell, Claudia; Kim, Jung-Hyun; Balinsha, Maria; Dorhout, Denise; Santos Fernandez, Cten; Baas, Marianne; Sinninghe Damsté, Jaap S.

2014-05-01

Branched glycerol dialkyl glycerol tetraethers (brGDGTs), which are transported from soil to marine sediment by rivers, have been used to reconstruct the mean annual air temperature(MAAT) and soil pH of the drainage basin using the methylation index of branched tetraethers(MBT, recently refined as MBT') and cyclization index of branched tetraethers (CBT) from coastal marine sediment records. In this study we are tracing the brGDGTs from source to sink in the Tagus River basin, the longest river system on the Iberian Peninsula, by determining their concentration and distribution in soils, river suspended particulate matter (SPM), riverbank sediments, marine SPM, and marine surface sediments. The concentrations of brGDGTs in river SPM were substantially higher and their distributions were different compared to those of the drainage basin soils. This indicates that brGDGTs are mainly produced in the river itself. In the marine environment, the brGDGT concentrations rapidly decreased with increasing distance from the Tagus estuary. At the same time, the brGDGT distributions in marine sediments also changed,indicating that marine in-situ production also takes place. These results show that there are various problems that complicate the use of the MBT'/CBT for paleoreconstructions using coastal marine sediments in the vicinity of a river. However, if the majority of brGDGTs are produced in the river, it might be possible to reconstruct the environmental (temperature and pH) conditions of the river water using appropriate aquatic calibrations, provided that marine core locations are chosen in such a way that the brGDGTs in their sediments are predominantly derived from riverine in-situ production.

Transport of branched tetraether lipids from the Tagus River basin to the coastal ocean of the Portuguese margin: consequences for the interpretation of the MBT'/CBT paleothermometer

NASA Astrophysics Data System (ADS)

Zell, C.; Kim, J.-H.; Balsinha, M.; Dorhout, D.; Fernandes, C.; Baas, M.; Sinninghe Damsté, J. S.

2014-03-01

Branched glycerol dialkyl glycerol tetraethers (brGDGTs), which are transported from soil to marine sediment by rivers, have been used to reconstruct the mean annual air temperature (MAAT) and soil pH of the drainage basin using the methylation index of branched tetraethers (MBT, recently refined as MBT') and cyclization index of branched tetraethers (CBT) from coastal marine sediment records. In this study we are tracing the brGDGTs from source to sink in the Tagus River basin, the longest river system on the Iberian Peninsula, by determining their concentration and distribution in soils, river suspended particulate matter (SPM), riverbank sediments, marine SPM, and marine surface sediments. The concentrations of brGDGTs in river SPM were substantially higher and their distributions were different compared to those of the drainage basin soils. This indicates that brGDGTs are mainly produced in the river itself. In the marine environment, the brGDGT concentrations rapidly decreased with increasing distance from the Tagus estuary. At the same time, the brGDGT distributions in marine sediments also changed, indicating that marine in-situ production also takes place. These results show that there are various problems that complicate the use of the MBT'/CBT for paleoreconstructions using coastal marine sediments in the vicinity of a river. However, if the majority of brGDGTs are produced in the river, it might be possible to reconstruct the environmental (temperature and pH) conditions of the river water using appropriate aquatic calibrations, provided that marine core locations are chosen in such a way that the brGDGTs in their sediments are predominantly derived from riverine in-situ production.

Transport of branched tetraether lipids from the Tagus River basin to the coastal ocean of the Portuguese margin: consequences for the interpretation of the MBT'/CBT paleothermometer

NASA Astrophysics Data System (ADS)

Zell, C.; Kim, J.-H.; Balsinha, M.; Dorhout, D.; Fernandes, C.; Baas, M.; Sinninghe Damsté, J. S.

2014-10-01

Branched glycerol dialkyl glycerol tetraethers (brGDGTs), which are thought to be transported from soil to marine sediment by rivers, have been used to reconstruct the mean annual air temperature (MAAT) and soil pH of the drainage basin using the methylation index of branched tetraethers (MBT, recently refined as MBT') and cyclization index of branched tetraethers (CBT) from coastal marine sediment records. In this study, we trace the brGDGTs from source to sink in the Tagus River basin, the longest river system on the Iberian Peninsula, by determining their concentration and distribution in soils, river suspended particulate matter (SPM), riverbank sediments, marine SPM, and marine surface sediments. The concentrations of brGDGTs in river SPM were substantially higher and their distributions were different compared to those of the drainage basin soils. This indicates that brGDGTs are mainly produced in the river itself. In the marine environment, the brGDGT concentrations rapidly decreased with increasing distance from the Tagus estuary. At the same time, the brGDGT distributions in marine sediments also changed, indicating that marine in situ production also takes place. These results show that there are various problems that complicate the use of the MBT'/CBT for paleoreconstructions using coastal marine sediments in the vicinity of a river. However, if the majority of brGDGTs are produced in the river, it might be possible to reconstruct the environmental (temperature and pH) conditions of the river water using appropriate aquatic calibrations, provided that marine core locations are chosen in such a way that the brGDGTs in their sediments are predominantly derived from riverine in situ production.

Riverine input of organic carbon and nitrogen in water-sediment system from the Yellow River estuary reach to the coastal zone of Bohai Sea, China

NASA Astrophysics Data System (ADS)

Wang, Chuanyuan; Lv, Yingchun; Li, Yuanwei

2018-04-01

The temporal-spatial distribution of the carbon and nitrogen contents and their isotopic compositions of suspended matter and sediments from the Yellow River estuary reach (YRER), the estuary to the offshore area were measured to identify the source of organic matter. The higher relative abundances of suspended and sedimentary carbon and nitrogen (POC, TOC, PN and TN) in the offshore marine area compared to those of the riverine and estuarine areas may be due to the cumulative and biological activity impact. The organic matter in surface sediments of YRER, the estuary and offshore area of Bohai Sea is basically the mixture of continental derived material and marine material. The values of δ13Csed fluctuate from values indicative of a land source (- 22.50‰ ± 0.31) to those indicative of a sea source (- 22.80‰ ± 0.38), which can be attributed to the fine particle size and decrease in terrigenous inputs to the offshore marine area. Contrary to the slight increase of POC and PN during the dry season, TOC and TN contents of the surface sediments during the flood season (October) were higher than those during the dry season (April). The seasonal differences in water discharge and suspended sediment discharge of the Yellow River Estuary may result in seasonal variability in TOC, POC, TN and PN concentrations in some degree. Overall, the surface sediments in the offshore area of Bohai Sea are dominated by marine derived organic carbon, which on average, accounts for 58-82% of TOC when a two end-member mixing model is applied to the isotopic data.

Patterns and drivers of bacterial α- and β-diversity across vertical profiles from surface to subsurface sediments.

PubMed

Luna, Gian Marco; Corinaldesi, Cinzia; Rastelli, Eugenio; Danovaro, Roberto

2013-10-01

We investigated the patterns and drivers of bacterial α- and β-diversity, along with viral and prokaryotic abundance and the carbon production rates, in marine surface and subsurface sediments (down to 1 m depth) in two habitats: vegetated sediments (seagrass meadow) and non-vegetated sediments. Prokaryotic abundance and production decreased with depth in the sediment, but cell-specific production rates and the virus-to-prokaryote ratio increased, highlighting unexpectedly high activity in the subsurface. The highest diversity was observed in vegetated sediments. Bacterial β-diversity between sediment horizons was high, and only a minor number of taxa was shared between surface and subsurface layers. Viruses significantly contributed to explain α- and β-diversity patterns. Despite potential limitations due to the only use of fingerprinting techniques, this study indicates that the coastal subsurface host highly active and diversified bacterial assemblages, that subsurface cells are more active than expected and that viruses promote β-diversity and stimulate bacterial metabolism in subsurface layers. The limited number of taxa shared between habitats, and between surface and subsurface sediment horizons, suggests that future investigations of the shallow subsurface will provide insights into the census of bacterial diversity, and the comprehension of the patterns and drivers of prokaryotic diversity in marine ecosystems. © 2013 John Wiley & Sons Ltd and Society for Applied Microbiology.

Trace element concentrations in surface estuarine and marine sediments along the Mississippi Gulf Coast following Hurricane Katrina.

PubMed

Warren, Crystal; Duzgoren-Aydin, Nurdan S; Weston, James; Willett, Kristine L

2012-01-01

Hurricanes are relatively frequent ecological disturbances that may cause potentially long-term impacts to the coastal environment. Hurricane Katrina hit the Mississippi Gulf Coast in August 2005, and caused a storm surge with the potential to change the trace element content of coastal surface sediments. In this study, surface estuarine and marine sediments were collected monthly following the storm from ten sites along the Mississippi Gulf Coast (Mobile Bay, Grand Bay Bayous Heron and Cumbest, Pascagoula, Ocean Springs, Biloxi Gulf, Back Biloxi Bay, Gulfport Gulf, Gulfport Courthouse Rd, and Gulfport Marina). Concentrations of V, Cr, Mn, Fe, Co, Ni, Zn, As, Cd, and Pb were measured by inductively coupled plasma-mass spectrometry to evaluate their temporal and spatial variations in the year following Hurricane Katrina. Sediments were characterized by pH, particle size distribution and total carbon and nitrogen content. Trace element contents of the sediments were determined in both <2 mm and <63 μm grain size fractions. Results revealed no significant temporal and spatial variability in trace element concentrations, in either size fraction. Potential ecological risk of the sediments was assessed by using NOAA SQuiRTs' guideline values; most concentrations remained below probable adverse effects guidelines to marine organisms suggesting that trace elements redistributed by Hurricane Katrina would not cause an adverse impact on resident organisms. Instead, the concentrations of trace elements were site-dependent, with specific contaminants relating to the use of the area prior to Hurricane Katrina.

Techniques employed for detection of hot particles in the marine environment.

PubMed

Pillsbury, G D

2007-09-01

During the decommissioning of the Maine Yankee nuclear plant, several methods were developed and employed to survey for hot particles in the marine environment surrounding the site. The methods used and the sensitivities achieved in the search for environmentally dispersed particles during the various decommissioning activities performed are described in detail. Surveys were performed on dry soil, exposed marine sediment and submerged marine sediment. Survey techniques ranged from the use of the basic NaI detector coupled to a count rate meter to an intrinsic germanium detector deployed in a submarine housing coupled to a multi-channel analyser. The initial surveys consisted of collecting samples of marine sediment, spreading them out over a 1 m2 surface in a thin layer, and scanning the deposited sediment by hand using a 5 cm by 5 cm NaI detector coupled to a standard count rate meter. This technique was later replaced by walkover scans with the 5 cm by 5 cm NaI detector moved in a serpentine pattern over the sediment surface. By coupling the detector to a 'smart meter', an alarm set point could be used to alert the surveyor to the presence of a particle within the instrument's field of view. A similar technique, with the detector mounted in a watertight housing secured to the end of a pole, was also employed to scan underwater locations. The most sensitive method developed for performing underwater surveys was the use of the intrinsic germanium detector placed in a submarine housing. Detailed descriptions of the methods employed and the results obtained are presented. This work demonstrates that there are several approaches to surveying for discrete particles in the marine environment and the relative merits of each are considered.

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

PubMed

Wasmund, Kenneth; Mußmann, Marc; Loy, Alexander

2017-08-01

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. © 2017 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

Microplastic pollution in North Yellow Sea, China: Observations on occurrence, distribution and identification.

PubMed

Zhu, Lin; Bai, Huaiyu; Chen, Bijuan; Sun, Xuemei; Qu, Keming; Xia, Bin

2018-09-15

Microplastics are emerging contaminants and have attracted widespread environmental concerns about their negative effects on the marine ecosystems. In this study, we investigated the abundances, distributions and characteristics of microplastics in surface seawater and sediments from the North Yellow Sea. The results showed that the abundance of microplastics was 545 ± 282 items/m 3 in surface seawater and 37.1 ± 42.7 items/kg dry weight in sediments, representing a medium microplastic pollution level compared with other sea areas. Small microplastics (<1 mm) made up >70% of the total microplastic numbers. Films and fibers were the dominant shapes of microplastics in both the surface seawater and sediments. Transparent microplastics were generally more common than microplastics of other colors. Based on the identification by a Fourier transform infrared microscope, polyethylene (PE) was the dominant composition of microplastics in surface seawater, while polypropylene (PP) was the most common polymer type in sediments. These results will improve our understanding of the environmental risks posed by microplastics to marine ecosystems. Copyright © 2018 Elsevier B.V. All rights reserved.

Formation of natural gas hydrates in marine sediments. Gas hydrate growth and stability conditioned by host sediment properties

USGS Publications Warehouse

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

2000-01-01

The stability conditions of submarine gas hydrates (methane clathrates) are largely dictated by pressure, temperature, gas composition, and pore water salinity. However, the physical properties and surface chemistry of the host sediments also affect the thermodynamic state, growth kinetics, spatial distributions, and growth forms of clathrates. Our model presumes that gas hydrate behaves in a way analogous to ice in the pores of a freezing soil, where capillary forces influence the energy balance. Hydrate growth is inhibited within fine-grained sediments because of the excess internal phase pressure of small crystals with high surface curvature that coexist with liquid water in small pores. Therefore, the base of gas hydrate stability in a sequence of fine sediments is predicted by our model to occur at a lower temperature, and so nearer to the seabed than would be calculated from bulk thermodynamic equilibrium. The growth forms commonly observed in hydrate samples recovered from marine sediments (nodules, sheets, and lenses in muds; cements in sand and ash layers) can be explained by a requirement to minimize the excess of mechanical and surface energy in the system.

Iron geochemistry and organic carbon preservation by iron (oxyhydr)oxides in surface sediments of the East China Sea and the south Yellow Sea

NASA Astrophysics Data System (ADS)

Ma, Wei-Wei; Zhu, Mao-Xu; Yang, Gui-Peng; Li, Tie

2018-02-01

In marine sediments factors that influence iron (Fe) geochemistry and its interactions with other elements are diverse and remain poorly understood. Here we comparatively study Fe speciation and reactive Fe-bound organic carbon (Fe-OC) in surface sediments of the East China Sea (ECS) and the south Yellow Sea (SYS). The objectives are to better understand the potential impacts of geochemically distinct sediment sources and depositional/diagenetic settings on Fe geochemistry and OC preservation by Fe (hydr)oxides in sediments of the two extensive shelf seas around the world. Contents of carbonate- and acid-volatile-sulfide (AVS)-associated Fe(II) (FeAVS + carb) and magnetite (Femag) in the ECS sediments are about 5 and 9 times higher, respectively, than in the SYS. This could be ascribed to the ferruginous conditions of the ECS sediments that favor the formation/accumulation of Fecarb and Femag, a unique feature of marine unsteady depositional regimes. Much lower total Fe(II) contents in the SYS than in the ECS suggest that lower availability of highly reactive Fe (FeHR) and/or weak Fe reduction is a factor limiting Fe(II) formation and accumulation in the SYS sediments. The ratio of FeHR to total Fe is, on average, markedly higher (2.4 times) in the ECS sediments than in the SYS, which may be a combined result of several factors relevant to different sediment sources and depositional/diagenetic settings. In comparison with many other marine sediments, the percent fractions (fFe-OC) of Fe-OC to total organic carbon (TOC) in the ECS and the SYS are low, which can be ascribed to surface adsorption of OC rather than coprecipitation or organic complexation as the dominant binding mechanisms. Based on the fFe-OC in this study, total Fe-OC estimated for global continental shelves is equivalent to 38% of the atmospheric CO2 pool, which indicates the important role of sorptive stabilization of Fe-OC in continental shelf sediments for buffering CO2 release to the atmosphere. In the SYS, consistently less 13C-depleted Fe-OC relative to 13C of non-Fe-bound OC (13Cnon-Fe-OC) suggests selective sequestration of labile marine OC in the marine OC-dominated sediments of the central SYS. In the ECS, however, efficient oxidation of OC and frequent redox cycling of Fe in the unsteady depositional regimes may complicate the isotopic compositions of Fe-OC. A combination of our results and literature data demonstrates that Fe-OC contents are strongly dependent on the availability of TOC and reactive Fe, but the fFe-OC is primarily controlled by the processes of Fe redox cycling in the sediments.

Terrestrial and marine biomarker estimates of organic matter sources and distributions in surface sediments from the East China Sea shelf

NASA Astrophysics Data System (ADS)

Xing, Lei; Zhang, Hailong; Yuan, Zineng; Sun, Yao; Zhao, Meixun

2011-07-01

Revealing of the sources and distributions of sedimentary organic matter in the East China Sea (ECS) is important for understanding its carbon cycle, which has significant temporal and spatial variability due to the influences of recent climate changes and anthropogenic activities. In this study, we report the contents of both terrestrial and marine biomarkers including ∑C 27+C 29+C 31n-alkanes (38.6-580 ng/g), C 37 alkenones (5.6-124.6 ng/g), brassicasterol (98-913 ng/g) and dinosterol (125-1521 ng/g) from the surface sediments in the Changjiang River Estuary (CRE) and shelf areas of the ECS. Several indices based on biomarker contents and ratios are calculated to assess the spatial distributions of both terrestrial and marine organic matter in the ECS surface sediments, and these results are compared with organic matter distribution patterns revealed by the δ13C (-20.1‰ to -22.7‰) and C/N ratio (5-7.5) of total organic matter. The contents of terrestrial biomarkers in the ECS surface sediments decrease seaward, controlled mostly by Changjiang River (CR) inputs and surface currents; while higher contents of the two marine biomarkers (brassicasterol and dinosterol) occur in upwelling areas outside the CRE and in the Zhejiang-Fujian coastal zone, controlled mostly by marine productivity. Four proxies, fTerr( δ13C) (the fraction of terrestrial organic matter in TOC estimated by TOC δ13C), odd-alkanes (∑C 27+C 29+C 31n-alkanes), 1/ Pmar-aq ((C 23+C 25+C 29+C 31)/(C 23+C 25) n-alkanes) and TMBR (terrestrial and marine biomarker ratio) (C 27+C 29+C 31n-alkanes)/((C 27+C 29+C 31) n-alkanes+(brassicasterol+dinosterol+alkenones)), reveal a consistent pattern showing the relative contribution of terrestrial organic matter (TOM) is higher in the CRE and along the Zhejiang-Fujian coastline, controlled mostly by CR inputs and currents, but the TOM contribution decreases seaward, as the influences of the CR discharge decrease.

14C and delta13C characteristics of organic matter and carbonate in saltmarsh sediments from south west Scotland.

PubMed

MacKenzie, A B; Cook, G T; Barth, J; Gulliver, P; McDonald, P

2004-05-01

The distribution of contaminant radionuclides from the Sellafield nuclear fuel reprocessing plant was used to establish chronologies for three saltmarsh sediment cores from south west Scotland. delta(13)C and (14)C analyses indicated that the cores provided a useful archive record of variations in input of organic matter and carbonate. The results imply that prior to major releases of contaminant (14)C from Sellafield, the (14)C specific activity of organic matter in Irish Sea offshore sediments was about 24 Bq kg(-1) C, while that of the carbonate component was below the limit of detection. These results provide baseline data for modelling the uptake of contaminant (14)C by the Irish Sea sediment system. The study confirmed that small(13)C analyses provide a sensitive means of apportioning the origin of saltmarsh organic matter between C(3) terrigenous plants, C(4) terrigenous plants and suspended particulate marine organic matter. For the <2 mm fraction of sediment, a clear pattern of decreasing marine organic input was observed in response to increasing elevation of the marsh surface as a result of sediment accumulation. Bulk sediment, including detrital vegetation, had a dominant input from terrigenous plants. The combined use of delta(13)C and (14)C data revealed that organic matter in the marine organic component of the <2 mm fraction of contemporary surface sediments of the saltmarshes is dominated by recycled old organic material.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 epoxidesmore » in these pigments, a feature which causes rapid cleavage of the polyene and fragmentation to low molecular weight compounds.« less

The distribution of triclosan and methyl-triclosan in marine sediments of Barker Inlet, South Australia.

PubMed

Fernandes, Milena; Shareef, Ali; Kookana, Rai; Gaylard, Sam; Hoare, Sonja; Kildea, Tim

2011-04-01

In this work, we investigated the transport and burial of triclosan and its methylated derivative, in surface sediments near the mouth of Barker Inlet in South Australia. The most likely source of this commonly used bactericide to the area is a wastewater outfall discharging at the confluence of the inlet with marine waters. Triclosan was detected in all samples, at concentrations (5-27 μg kg(-1)) comparable to values found in other surface sediments under the influence of marine wastewater outfalls. Its dispersal was closely associated with fine and organic-rich fractions of the sediments. Methyl-triclosan was detected in approximately half of the samples at concentrations <11 μg kg(-1). The occurrence of this compound was linked to both wastewater discharges and biological methylation of the parent compound. Wastewater-borne methyl-triclosan had a smaller spatial footprint than triclosan and was mostly deposited in close proximity to the outfall. In situ methylation of triclosan likely occurs at deeper depositional sites, whereas the absence of methyl-triclosan from shallower sediments was potentially explained by photodegradation of the parent compound. Based on partition equilibrium, a concentration of triclosan in the order of 1 μg L(-1) was estimated in sediment porewaters, a value lower than the threshold reported for harmful effects to occur in the couple of species of marine phytoplankton investigated to date. Methyl-triclosan presents a greater potential for bioaccumulation than triclosan, but the implications of its occurrence to aquatic ecosystem health are difficult to predict given the lack of ecotoxicological data in the current literature.

Heavy metal assessment in surface sediments off Coromandel Coast of India: Implication on marine pollution.

PubMed

N, Anbuselvan; D, Senthil Nathan; M, Sridharan

2018-06-01

The present study investigates the distribution of heavy metals (Fe, Cd, Co, Cr, Cu, Ni, Zn and Pb) in the surface sediments along the Coromandel Coast of Bay of Bengal as an indicator of marine pollution. Pollution indices such as Contamination factor (CF), Enrichment factor (EF) and Geo-accumulation index (I) were performed to assess the spatial distribution and pollution status of the study area. The heavy metal concentration in the study area is closely associated with grain size and organic matter. Both geoaccumulation index and metal contamination factor indicate that the sediments are free from contamination with regards to the metals Cr and Ni, followed by uncontamination to moderate contamination of Co, Cu and Zn. However, sediments are found to be extremely polluted with respect to Cd and Pb. Factor analysis reveals that the accumulation of these heavy metals in the shelf sediments are due to anthropogenic inputs from the adjacent land area. Copyright © 2018 Elsevier Ltd. All rights reserved.

Tracing tetraether lipids from source to sink in the Rhône River system (NW Mediterranean)

NASA Astrophysics Data System (ADS)

Kim, Jung-Hyun; Ludwig, Wolfgang; Buscail, Roselyne; Dorhout, Denise; Sinninghe Damste, Jaap

2015-06-01

In this study, we investigated soils and river suspended particulate matter (SPM) collected in the Rhône and its tributary basins as well as marine surface sediments taken in the Rhône prodelta (Gulf of Lions, NW Mediterranean). Thereby, we traced the signal of branched glycerol dialkyl glycerol tetraethers (brGDGTs) from the source to sink via the Rhône River and its tributaries and identified sources of brGDGTs in rivers and marine sediments. Soil pH rather than the mean annual air temperature (MAAT) explains most of the observed variances of the brGDGT distribution in our soil dataset. The observed changes in the distribution of brGDGTs in the river SPM indicate that brGDGTs brought by the river to the sea are primarily derived from the lower Rhône and its tributary soils, even though in situ production in the river itself cannot be excluded. In marine surface sediments, it appears that the input of riverine brGDGTs is the primary source of brGDGTs in the Rhône prodelta, although the brGDGT composition may be further modified by the in situ production in the marine environment. More work is required to assess fully whether brGDGTs can be used to reconstruct the terrestrial paleoenvironmental changes using marine sediment cores taken in the Rhône prodelta close to the river mouth.

MEASURING CONTAMINANT RESUSPENSION RESULTING FROM SEDIMENT CAPPING

EPA Science Inventory

This Sediment Issue summarizes two studies undertaken at marine sites by the National Risk Management Research Laboratory of U.S. EPA to evaluate the resuspension of surface materials contaminated with polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) b...

C5 glycolipids of heterocystous cyanobacteria track symbiont abundance in the diatom Hemiaulus hauckii across the tropical North Atlantic

NASA Astrophysics Data System (ADS)

Bale, Nicole J.; Villareal, Tracy A.; Hopmans, Ellen C.; Brussaard, Corina P. D.; Besseling, Marc; Dorhout, Denise; Sinninghe Damsté, Jaap S.; Schouten, Stefan

2018-03-01

Diatom-diazotroph associations (DDAs) include marine heterocystous cyanobacteria found as exosymbionts and endosymbionts in multiple diatom species. Heterocysts are the site of N2 fixation and have thickened cell walls containing unique heterocyst glycolipids which maintain a low oxygen environment within the heterocyst. The endosymbiotic cyanobacterium Richelia intracellularis found in species of the diatom genus Hemiaulus and Rhizosolenia makes heterocyst glycolipids (HGs) which are composed of C30 and C32 diols and triols with pentose (C5) moieties that are distinct from limnetic cyanobacterial HGs with predominantly hexose (C6) moieties. Here we applied a method for analysis of intact polar lipids to the study of HGs in suspended particulate matter (SPM) and surface sediment from across the tropical North Atlantic. The study focused on the Amazon plume region, where DDAs are documented to form extensive surface blooms, in order to examine the utility of C5 HGs as markers for DDAs as well as their transportation to underlying sediments. C30 and C32 triols with C5 pentose moieties were detected in both marine SPM and surface sediments. We found a significant correlation between the water column concentration of these long-chain C5 HGs and DDA symbiont counts. In particular, the concentrations of both the C5 HGs (1-(O-ribose)-3,27,29-triacontanetriol (C5 HG30 triol) and 1-(O-ribose)-3,29,31-dotriacontanetriol (C5 HG32 triol)) in SPM exhibited a significant correlation with the number of Hemiaulus hauckii symbionts. This result strengthens the idea that long-chain C5 HGs can be applied as biomarkers for marine endosymbiotic heterocystous cyanobacteria. The presence of the same C5 HGs in surface sediment provides evidence that they are effectively transported to the sediment and hence have potential as biomarkers for studies of the contribution of DDAs to the paleo-marine N cycle.

Chromium isotopes in siliciclastic sediments and sedimentary rocks as a proxy for Earth surface redox

NASA Astrophysics Data System (ADS)

Reinhard, C. T.; Planavsky, N. J.; Wang, X.; Owens, J. D.; Johnson, T. M.; Fischer, W. W.; Lyons, T. W.

2013-12-01

Chromium (Cr) isotopes are an emerging and potentially promising proxy for tracking redox processes at Earth's surface. However, recent efforts to reconstruct the Cr isotope record through time have primarily focused on sporadically deposited iron-rich chemical sediments, with large temporal gaps and limited capacity to explore the Cr isotope record relative to modern and recent marine processes. However, the basic inorganic chemistry of Cr suggests that anoxic marine basins factor prominently in the global Cr cycle, and that likewise sediments deposited within anoxic basins may offer an unexplored Cr isotope archive throughout Earth's history. We present authigenic δ53Cr data from sediments of the Cariaco Basin, Venezuela--a ';type' environment on the modern Earth for large, perennially anoxic basins with relatively strong hydrological connections to the global ocean. Combined with currently available constraints on the δ53Cr composition of modern Atlantic seawater, these data are consistent with the hypothesis that anoxic marine basins can serve as a chemical archive of the first-order features of seawater δ53Cr variation. We employ a simple quantitative model to explore the implications of this hypothesis for global Cr isotope mass balance and the possible utility of authigenic δ53Cr in anoxically deposited siliciclastic sediments and sedimentary rocks as a global paleoredox proxy. Our focus is a basic analysis of the primary controls on seawater δ53Cr as related to both the marine redox landscape and the processes involved in the weathering and aqueous-particulate transport of Cr at Earth's surface. As a case study, we provide analysis of new bulk δ53Cr data through a Cretaceous Oceanic Anoxic Event (OAE-2), which shows a well-defined ~1.0‰ negative excursion during the event coupled with evidence for a drawdown of the marine Cr reservoir. We present a conceptual model to explain these observations, and interpret this shift to suggest a shutdown of internal oceanic Cr isotope fractionation associated with a perturbation to benthic marine redox.

Use of a Novel Sediment Exposure to Determine the Effects of ...

EPA Pesticide Factsheets

Triclosan (5-chloro-2-(2,4-dichlorophenoxy) phenol) is a relatively new, commonly used antimicrobial compound found in many personal care products. Triclosan is toxic to marine organisms at the ug/l level, can photo-degrade to a dioxin, accumulate in humans, and has been found to be stable in marine sediments for over 30 years. To determine the effects of triclosan on marine benthic communities, we brought intact sediment cores into the laboratory and held them under flowing seawater conditions. A two cm layer of triclosan-spiked sediment was applied to the surface, and after a two-week exposure the meio- and macrofaunal communities were assessed for differences in composition relative to non-spiked core. The High Triclosan treatment (180 mg/kg dry weight) affected both the meio- and macro benthic communities. There were no discernable differences in the Low Triclosan treatment (14 mg/kg dry weight dry). This exposure method is effective for testing benthic community response to sediment contaminants, but improvements should be made as to the amount and method of applying the overlying sediment to prevent smothering of fragile benthic organisms. This paper describes the effects of triclosan on meio- and macro-benthic marine communities. It describes a novel system of whole benthic community exposure that is a promising method to evaluate effects on intact marine benthic communities. Triclosan concentrations greater than 180 mg/kg dry weight had a signif

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scott, Nicole M.; Hess, Matthias; Bouskill, Nick J.

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 ofmore » 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. Furthermore, 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.« less

The Toba Volcanic Event and Interstadial/Stadial Climates at the Marine Isotopic Stage 5 to 4 Transition in the Northern Indian Ocean

NASA Astrophysics Data System (ADS)

Schulz, Hartmut; Emeis, Kay-Christian; Erlenkeuser, Helmut; von Rad, Ulrich; Rolf, Christian

2002-01-01

The Toba volcanic event, one of the largest eruptions during the Quaternary, is documented in marine sediment cores from the northeastern Arabian Sea. On the crest of the Murray Ridge and along the western Indian continental margin, we detected distinct concentration spikes and ash layers of rhyolithic volcanic shards near the marine isotope stage 5-4 boundary with the chemical composition of the "Youngest Toba Tuff." Time series of the U k'37-alkenone index, planktic foraminiferal species, magnetic susceptibility, and sediment accumulation rates from this interval show that the Toba event occurred between two warm periods lasting a few millennia. Using Toba as an instantaneous stratigraphic marker for correlation between the marine- and ice-core chronostratigraphies, these two Arabian Sea climatic events correspond to Greenland interstadials 20 and 19, respectively. Our data sets thus depict substantial interstadial/stadial fluctuations in sea-surface temperature and surface-water productivity. We show that variable terrigenous (eolian) sediment supply played a crucial role in transferring and preserving the productivity signal in the sediment record. Within the provided stratigraphic resolution of several decades to centennials, none of these proxies shows a particular impact of the Toba eruption. However, our results are additional support that Toba, despite its exceptional magnitude, had only a minor impact on the evolution of low-latitude monsoonal climate on centennial to millennial time scales.

Diverse molecular signatures for ribosomally ‘active’ Perkinsea in marine sediments

PubMed Central

2014-01-01

Background Perkinsea are a parasitic lineage within the eukaryotic superphylum Alveolata. Recent studies making use of environmental small sub-unit ribosomal RNA gene (SSU rDNA) sequencing methodologies have detected a significant diversity and abundance of Perkinsea-like phylotypes in freshwater environments. In contrast only a few Perkinsea environmental sequences have been retrieved from marine samples and only two groups of Perkinsea have been cultured and morphologically described and these are parasites of marine molluscs or marine protists. These two marine groups form separate and distantly related phylogenetic clusters, composed of closely related lineages on SSU rDNA trees. Here, we test the hypothesis that Perkinsea are a hitherto under-sampled group in marine environments. Using 454 diversity ‘tag’ sequencing we investigate the diversity and distribution of these protists in marine sediments and water column samples taken from the Deep Chlorophyll Maximum (DCM) and sub-surface using both DNA and RNA as the source template and sampling four European offshore locations. Results We detected the presence of 265 sequences branching with known Perkinsea, the majority of them recovered from marine sediments. Moreover, 27% of these sequences were sampled from RNA derived cDNA libraries. Phylogenetic analyses classify a large proportion of these sequences into 38 cluster groups (including 30 novel marine cluster groups), which share less than 97% sequence similarity suggesting this diversity encompasses a range of biologically and ecologically distinct organisms. Conclusions These results demonstrate that the Perkinsea lineage is considerably more diverse than previously detected in marine environments. This wide diversity of Perkinsea-like protists is largely retrieved in marine sediment with a significant proportion detected in RNA derived libraries suggesting this diversity represents ribosomally ‘active’ and intact cells. Given the phylogenetic range of hosts infected by known Perkinsea parasites, these data suggest that Perkinsea either play a significant but hitherto unrecognized role as parasites in marine sediments and/or members of this group are present in the marine sediment possibly as part of the ‘seed bank’ microbial community. PMID:24779375

Surface Ocean Radiocarbon Reservoir Ages From Land-Sea Tephra Correlation Constrains Deglacial Chronology and Ocean Circulation in the Southeast Bering Sea

NASA Astrophysics Data System (ADS)

Cook, M. S.; Miller, R.; White-Nockleby, C.; Chapman, A.; Mix, A. C.

2017-12-01

Radiocarbon estimates of the past ocean are valuable because unlike passive tracers, radiocarbon has the potential to trace both the distribution and rate of transport of water masses. Most studies using paired radiocarbon measurements on planktonic and benthic foraminifera assume that the surface reservoir age was constant at the preindustrial value, which if incorrect, can strongly bias radiocarbon reconstructions. The subarctic Pacific is ringed by volcanic arcs, and there is great potential to use tephrochronology as a stratigraphic tool in sediments from the last glacial and deglaciation, and assign calendar ages to the marine sediment without relying on calibrated planktonic radiocarbon ages. In this study, we use major and trace element analysis of volcanic glass to match tephras between radiocarbon-dated lake cores from Sanak Island in the eastern Aleutians to marine cores from Umnak Plateau in the southeast Bering Sea. There are numerous thin tephras preserved in laminated sediments from the Bolling-Allerod and early Holocene in marine cores from depths (1000-1500 m) within the modern oxygen minimum zone. We find that trace elements are crucial in distinguishing tephras from individual eruptions. Our preliminary radiocarbon measurements suggest that the benthic-atmosphere radiocarbon differences and marine surface reservoir ages in the Bolling-Allerod are similar to pre-industrial values, supporting previously published radiocarbon reconstructions from the region.

Supervised classification of continental shelf sediment off western Donegal, Ireland

NASA Astrophysics Data System (ADS)

Monteys, X.; Craven, K.; McCarron, S. G.

2017-12-01

Managing human impacts on marine ecosystems requires natural regions to be identified and mapped over a range of hierarchically nested scales. In recent years (2000-present) the Irish National Seabed Survey (INSS) and Integrated Mapping for the Sustainable Development of Ireland's Marine Resources programme (INFOMAR) (Geological Survey Ireland and Marine Institute collaborations) has provided unprecedented quantities of high quality data on Ireland's offshore territories. The increasing availability of large, detailed digital representations of these environments requires the application of objective and quantitative analyses. This study presents results of a new approach for sea floor sediment mapping based on an integrated analysis of INFOMAR multibeam bathymetric data (including the derivatives of slope and relative position), backscatter data (including derivatives of angular response analysis) and sediment groundtruthing over the continental shelf, west of Donegal. It applies a Geographic-Object-Based Image Analysis software package to provide a supervised classification of the surface sediment. This approach can provide a statistically robust, high resolution classification of the seafloor. Initial results display a differentiation of sediment classes and a reduction in artefacts from previously applied methodologies. These results indicate a methodology that could be used during physical habitat mapping and classification of marine environments.

Different Planctomycetes diversity patterns in latitudinal surface seawater of the open sea and in sediment.

PubMed

Shu, Qinglong; Jiao, Nianzhi

2008-04-01

The 16S rRNA gene approach was applied to investigate the diversity of Planctomycetes in latitudinal surface seawater of the Western Pacific Ocean. The results revealed that the Pirellula-Rhodopirellula-Blastopirellula clade dominated the Planctomycetes community at all surface seawater sites while the minority genera Gemmata and Planctomyces were only found at sites H5 and H2 respectively. Although the clone frequency of the PRB clade seemed stable (between 83.3% and 94.1%) for all surface seawater sites, the retrieved Pirellula-Rhodopirellula-Blastopirellula clade presented unexpected diversity. Interestingly, low latitude seawater appeared to have higher diversity than mid-latitudes. integral-LIBSHUFF software analysis revealed significantly different diversity patterns between in latitudinal surface seawater and in the sediment of South China Sea station M2896. Our data suggested that different hydrological and geographic features contributed to the shift of Planctomycetes diversity in marine environments. This is, to our knowledge, the first systematic assessment of Planctomycetes in latitudinal surface seawater of the open sea and the first comparison of diversity pattern between surface seawater and sediments and has broadened our understanding of Planctomycetes diversity in marine environments.

Copper in the sediment and sea surface microlayer near a fallowed, open-net fish farm.

PubMed

Loucks, Ronald H; Smith, Ruth E; Fisher, Clyde V; Fisher, E Brian

2012-09-01

Sediment and sea surface microlayer samples near an open-net salmon farm in Nova Scotia, were analysed for copper. Copper is a constituent of the feed and is an active ingredient of anti-foulants. The salmon farm was placed in fallow after 15 years of production. Sampling was pursued over 27 months. Elevated copper concentrations in the sediments indicated the farm site as a source. Bubble flotation due to gas-emitting sediments from eutrophication is a likely process for accumulating copper in the sea surface microlayer at enriched concentrations. Elevated and enriched concentrations in the sea surface microlayer over distance from the farm site led, as a result of wind-drift, to an enlarged farm footprint. The levels of copper in both sediments and sea surface microlayer exceeded guidelines for protection of marine life. Over the 27 months period, copper levels persisted in the sediments and decreased gradually in the sea surface microlayer. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of Redox Conditions on Bacterial Community Structure in Baltic Sea Sediments with Contrasting Phosphorus Fluxes

PubMed Central

Steenbergh, Anne K.; Bodelier, Paul L. E.; Slomp, Caroline P.; Laanbroek, Hendrikus J.

2014-01-01

Phosphorus release from sediments can exacerbate the effect of eutrophication in coastal marine ecosystems. The flux of phosphorus from marine sediments to the overlying water is highly dependent on the redox conditions at the sediment-water interface. Bacteria are key players in the biological processes that release or retain phosphorus in marine sediments. To gain more insight in the role of bacteria in phosphorus release from sediments, we assessed the effect of redox conditions on the structure of bacterial communities. To do so, we incubated surface sediments from four sampling sites in the Baltic Sea under oxic and anoxic conditions and analyzed the fingerprints of the bacterial community structures in these incubations and the original sediments. This paper describes the effects of redox conditions, sampling station, and sample type (DNA, RNA, or whole-cell sample) on bacterial community structure in sediments. Redox conditions explained only 5% of the variance in community structure, and bacterial communities from contrasting redox conditions showed considerable overlap. We conclude that benthic bacterial communities cannot be classified as being typical for oxic or anoxic conditions based on community structure fingerprints. Our results suggest that the overall structure of the benthic bacterial community has only a limited impact on benthic phosphate fluxes in the Baltic Sea. PMID:24667801

Effect of redox conditions on bacterial community structure in Baltic Sea sediments with contrasting phosphorus fluxes.

PubMed

Steenbergh, Anne K; Bodelier, Paul L E; Slomp, Caroline P; Laanbroek, Hendrikus J

2014-01-01

Phosphorus release from sediments can exacerbate the effect of eutrophication in coastal marine ecosystems. The flux of phosphorus from marine sediments to the overlying water is highly dependent on the redox conditions at the sediment-water interface. Bacteria are key players in the biological processes that release or retain phosphorus in marine sediments. To gain more insight in the role of bacteria in phosphorus release from sediments, we assessed the effect of redox conditions on the structure of bacterial communities. To do so, we incubated surface sediments from four sampling sites in the Baltic Sea under oxic and anoxic conditions and analyzed the fingerprints of the bacterial community structures in these incubations and the original sediments. This paper describes the effects of redox conditions, sampling station, and sample type (DNA, RNA, or whole-cell sample) on bacterial community structure in sediments. Redox conditions explained only 5% of the variance in community structure, and bacterial communities from contrasting redox conditions showed considerable overlap. We conclude that benthic bacterial communities cannot be classified as being typical for oxic or anoxic conditions based on community structure fingerprints. Our results suggest that the overall structure of the benthic bacterial community has only a limited impact on benthic phosphate fluxes in the Baltic Sea.

Relative importance of methylotrophic methanogenesis in sediments of the Western Mediterranean Sea

NASA Astrophysics Data System (ADS)

Zhuang, Guang-Chao; Heuer, Verena B.; Lazar, Cassandre S.; Goldhammer, Tobias; Wendt, Jenny; Samarkin, Vladimir A.; Elvert, Marcus; Teske, Andreas P.; Joye, Samantha B.; Hinrichs, Kai-Uwe

2018-03-01

Microbial production of methane is an important terminal metabolic process during organic matter degradation in marine sediments. It is generally acknowledged that hydrogenotrophic and acetoclastic methanogenesis constitute the dominant pathways of methane production; the importance of methanogenesis from methylated compounds remains poorly understood. We conducted various biogeochemical and molecular genetic analyses to characterize substrate availability, rates of methanogenesis, and methanogen community composition, and further evaluated the contribution of different substrates and pathways for methane production in deltaic surface and subsurface sediments of the Western Mediterranean Sea. Major substrates representing three methanogenic pathways, including H2, acetate, and methanol, trimethylamine (TMA), and dimethylsulfide (DMS), were detected in the pore waters and sediments, and exhibited variability over depth and between sites. In accompanying incubation experiments, methanogenesis rates from various 14C labeled substrates varied as well, suggesting that environmental factors, such as sulfate concentration and organic matter quality, could significantly influence the relative importance of individual pathway. In particular, methylotrophic and hydrogenotrophic methanogenesis contributed to the presence of micromolar methane concentrations in the sulfate reduction zone, with methanogenesis from methanol accounting for up to 98% of the total methane production in the topmost surface sediment. In the sulfate-depleted zone, hydrogenotrophic methanogenesis was the dominant methanogenic pathway (67-98%), and enhanced methane production from acetate was observed in organic-rich sediment (up to 31%). Methyl coenzyme M reductase gene (mcrA) analysis revealed that the composition of methanogenic communities was generally consistent with the distribution of methanogenic activity from different substrates. This study provides the first quantitative assessment of methylotrophic methanogenesis in marine sediments and has important implications for marine methane cycling. The occurrence of methylotrophic methanogenesis in surface sediments could fuel the anaerobic oxidation of methane (AOM) in the shallow sulfate reduction zone. Release of methane produced from methylotrophic methanogenesis could be a source of methane efflux to the water column, thus influencing the benthic methane budgets.

Petroleum hydrocarbon concentrations in marine sediments along Chennai Coast, Bay of Bengal, India.

PubMed

Venkatachalapathy, R; Veerasingam, S; Ramkumar, T

2010-10-01

The spatial and temporal distribution of petroleum hydrocarbons (PHC) in marine sediments along the Chennai coast, Bay of Bengal was quantified by Ultra-Violet Fluorescence (UVF) Spectroscopy. The concentration of PHC in surface sediments varied from 1.88 to 39.76 ppm. The highest values obtained in the northern part of the study area, where shipping activities and land-based waste waters disposed into sea through the rivers like Kuvam and Adayar. The Adayar (7.26-16.83 ppm) and Kuvam (5.5-39.72 ppm) cores reveal a clear horizon of increase in PHC above 50 and 35 cm respectively. PHC values showed a decreasing pattern with depth in all sediment cores suggesting the excess anthropogenic loading occurring in the recent past. The present study revealed that the PHC values of Chennai coastal sediments are lower than the values reported from selected costal areas including the sediment of the Mumbai coast (7.6-42.8 ppm), Arabian Sea. The results will be useful for pollution monitoring program along the coastal region and also to check the level of petroleum hydrocarbons in marine sediments.

The origin, historical variations, and distribution of heavy metals in the Qiongzhou Strait and nearby marine areas

NASA Astrophysics Data System (ADS)

Zhang, Zhiqiang; Chen, Liang; Wang, Weiping; Li, Tuanjie; Zu, Tingting

2017-04-01

We analyzed heavy metal concentrations in a number of surface sediments and cores from the Qiongzhou Strait and surrounding marine areas. The areas of high concentrations are primarily outside the eastern mouth of the Qiongzhou Strait and on the west side of the Leizhou Peninsula, whereas the areas of low concentrations are located primarily in the eastern Qiongzhou Strait. The maximum Cd, Pb and Zn concentrations in the samples collected in our study do not exceed the official standards for marine sediments, whereas the concentrations of Cr and Cu slightly exceed the standards. Correlations exist between the concentrations of Cu, Pb, Zn, Cr and Cd, and the concentrations of these metals are positively correlated with the mean particle size (φ value), indicating that the finer sediments have adsorbed greater amounts of heavy metal elements than the coarser sediments. An evaluation of the potential environmental risks demonstrates that certain indices of heavy metal pollution and environmental risks are relatively low and may be assigned low risk levels, thereby indicating that, in terms of heavy metals, the marine sedimentary environment in this region is only mildly impacted. Our analysis of the contaminant origins shows that the heavy metals in this region primarily originate in the Pearl River Estuary and that a small amount of them is derived from local runoff. The elevated heavy metal concentrations from the upper sections of the cores started 130 years ago, which indicats that heavy metals in the surface sediments are primarily due to human activities associated with industrialization.

Environmental Radioactivity Study in Surface Sediments of Guacanayabo Gulf (Cuba)

NASA Astrophysics Data System (ADS)

Reyes, H.; López-Pino, N.; Rizo, O. Díaz; Bernal, J. L.; D'Alessandro, K.; Padilla, F.; Corrales, Y.; Casanova, O. A.; Gelen, A.; Martínez, Y.; Aguilar, J.; Arado, J. O.; Maidana, N. L.

2009-06-01

Sediment samples have been collected in the Guacanayabo gulf located in the southeast Cuba, to determinate the radioactivity levels of 210Pb, 234Th, 214Pb, 137Cs, 232Th and 40K using Low-Background Gamma Spectrometry and to evaluate its impact in the habitat of important marine species for fishery industry. The obtained results show the lowest radioactivity levels determined in Cuban marine environments. The species capture declination in the last years is not originated by radioactive pollution of the zone.

Anthropogenic and natural variability in the composition of sedimentary organic matter of the urbanised coastal zone of Montevideo (Río de la Plata).

PubMed

Bueno, C; Brugnoli, E; Bergamino, L; Muniz, P; García-Rodríguez, F; Figueira, R

2018-01-01

This study is aimed to identify the different sources of sedimentary organic matter (SOM) within Montevideo coastal zone (MCZ). To this end δ 13 C, δ 15 N and C/N ratio were analysed in surface sediments and a sediment core. Sediment core analysis showed that until ~1950CE SOM was mainly marine, observing a shift towards lower δ 13 C in recent sediments, evidencing an estuarine composition. This trend was associated to the climatic variability, which exerted a major influence on the SOM composition, leading to an increased input of terrigenous material and associated anthropogenic contaminants. Surface sediments collected during different El Niño South Oscillation (ENSO) phases did not show inter-annual variability in SOM composition, which was mainly marine in both eastern and western region of MCZ and estuarine in Montevideo Bay. This spatial pattern provides new insights on the dynamics and factors affecting organic matter sources available for primary consumers along the study region. Copyright © 2017 Elsevier Ltd. All rights reserved.

Occurrences, composition profiles and source identifications of polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in ship ballast sediments.

PubMed

Su, Peng-Hao; Lv, Bao-Yi; Tomy, Gregg T; Xu, Jin-Xiang; Tian, Wen; Hou, Chun-Yan; Yin, Fang; Li, Yi-Fan; Feng, Dao-Lun

2017-02-01

The aim of this study was to investigate the levels of persistent organic pollutants (POPs) including polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in ship ballast sediments. The ballast sediment samples were collected from six merchant ships docked in 2015 in Jiangyin City, China. Ballast sediments represent a potential vector for the transport of POPs and invasive species between marine environments. An attempt was also made to determine the sources of these compounds in the ballast sediment. The results indicated ballast sediments generally contain greater amounts of BDE-209 and comparable amounts of PAHs, PBDEs (exclusive of BDE-209) and PCBs compared to those in marine surface sediments. Based on the sediment quality guidelines, PAHs and PCBs in ballast sediments were estimated to have median or high potential of posing ecological risks, respectively, to marine life if ballast sediments were disposed without specific treatment. POPs in ballast sediments were derived from multiple sources with atmospheric deposition being an important origin. Ship activities including diesel exhaust and illegal oil sewage discharge were considerable contributors of certain individual POPs to ballast sediments. Our study is important because it represents the first report on levels, health risk assessment and source apportionments of POPs in ballast sediments and is a first step in the implementation of specific ballast sediment management measures. Copyright © 2016 Elsevier Ltd. All rights reserved.

Environmental assessment of creosote-treated pilings in the marine environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Butala, J.H.; Webb, D.A.; Jop, K.M.

1995-12-31

A comprehensive ecological risk assessment was conducted to evaluate the environmental impact of creosote-treated pilings in the marine environment at Moss Landing Harbor, Moss Landing, California. Four areas of investigation comprising the risk assessment were (1) evaluation of environmental conditions around existing creosote-treated pilings (2) investigating effects related to restoration of pilings (3) assessing creosote migration into surrounding environment, one year after pile-driving and (4) confirmation of creosote toxicity in laboratory studies. Biological and chemical evaluation of the impact of creosote-treated pilings was conducted on surface sheen, water column and sediment samples collected at Moss Landing Harbor. Water samples (surfacemore » sheen, water column and sediment pore water) were evaluated using short-term chronic exposures with Mysidopsis bahia, while bulk sediment samples were evaluated with 10-day sediment toxicity tests with Ampelisca abdita. Samples of surface, column water and sediment were analyzed for the constituents of creosote by GC mass spectrometry. In addition, a sample of neat material used to preserve treated pilings represented a reference for the polyaromatic hydrocarbons. Verification of organism response and analyses of field collected samples was performed by conducting 10-day A. abdita sediment and 7-day M. bahia elutriate exposures with creosote applied to clean sediment collected at Moss Landing, Evaluations were also performed to determine the effects of photoinduced toxicity on test organisms exposed to PAHs. The biological and analytical results of the field and laboratory exposures are being used to evaluate and determine risk of creosote-treated pilings on the marine environment.« less

Seasonal Rates of Methane Oxidation in Anoxic Marine Sediments

PubMed Central

Iversen, Niels; Blackburn, T. Henry

1981-01-01

Methane concentrations and rates of methane oxidation were measured in intact sediment cores from an inshore marine sediment at Jutland, Denmark. The rates of methane oxidation, determined by the appearance of 14CO2 from injected 14CH4, varied with sediment depth and season. Most methane oxidation was anoxic, but oxygen may have contributed to methane oxidation at the sediment surface. Cumulative rates (0- to 12-cm depth) for methane oxidation at Kysing Fjord were 3.34, 3.48, 8.60, and 17.04 μmol m−2 day−1 for April (4°C), May (13°C), July (17°C), and August (21°C), respectively. If all of the methane was oxidized by sulfate, it would account for only 0.01 to 0.06% of the sulfate reduction. The data indicate that methane was produced, in addition to being oxidized, in the 0- to 18-cm sediment stratum. PMID:16345784

Vertical and horizontal distribution of radionuclides (232Th, 238U and 40K) in sediment from Manjung coastal water area Perak, Malaysia

NASA Astrophysics Data System (ADS)

Abdullah, Anisa; Hamzah, Zaini; Saat, Ahmad; Wood, Ab. Khalik

2016-01-01

Distribution of radionuclides from anthropogenic activities has been widely studied in marine coastal area. Due to rapid population growth and socio-economic development in Manjung area such as coal fired power plant, iron foundries, port development, waste discharged from factories and agriculture runoff may contribute to increase in pollution rate. The radioactive materials from anthropogenic activities could deteriorate the quality of the marine ecosystem and thus lead to possible radiological health risk to the population. Radionuclides (232Th, 238U and 40K) content in surface and profile sediment from Manjung coastal area was determined in this study. Radionuclides in sediment from seven locations were collected using sediment core sampling and measurements were carried out using Energy Dispersive X-ray Fluorescence (EDXRF) spectroscopy. The results show that the concentration of radionuclides in surface sediment and distribution trend of depth vertical profile sediment generally varies depending on locations. Enrichment factors (EF), geo-accumulation index (Igeo) and pollution index (PI) were applied to determine level of pollution of this study area. The radiological risks related to human exposure were evaluated based on external hazard index (Hex).

Base of brackish-water mud as key regional stratigraphic marker of mid-Holocene marine flooding of the Baltic Sea Basin

NASA Astrophysics Data System (ADS)

Virtasalo, Joonas J.; Endler, Michael; Moros, Matthias; Jokinen, Sami A.; Hämäläinen, Jyrki; Kotilainen, Aarno T.

2016-12-01

Many modern epicontinental seas were dry land before their marine flooding by the mid-Holocene glacioeustatic sea-level rise, whereas the Baltic Sea Basin was covered by a huge postglacial lake. This change from a postglacial lake to the present-day semi-enclosed brackish-water sea is studied here in sediment cores and acoustic profiles from the Baltic Sea major sub-basins, based on novel datasets combined with information extracted from earlier publications. In shallow areas (<50m water depth), the base of the brackish-water mud is erosional and covered by a patchy, thin, transgressive silt-sand sheet resulting from decreased sediment supply, winnowing and the redistribution of material from local coarse-grained deposits during transgression. This erosional marine flooding surface becomes sharp and possibly erosional in deep areas (>50m water depth), where it may be locally less clearly expressed due to reworking and bioturbation. Both in the shallow and deep areas, the brackish-water mud is strongly enriched in organic matter compared to underlying sediments. Bioturbation type changes at the flooding surface in response to the increased sedimentary organic content, but no firm-ground ichnofacies were developed because of low erosion. It is concluded that the base of the brackish-water mud is a robust allostratigraphic bounding surface that is identifiable by the lithologic examination of cores over the Baltic Sea. The surface is a distinct reflector in seismic-acoustic profiles, which facilitates mapping and basin-wide stratigraphic subdivision. Detailed geochronologic studies are required to confirm if sediments immediately overlying the erosional flooding surface in shallow areas are younger than the basal part of the brackish-water mud in deep areas that is predicted to be time-equivalent to the erosion.

New ideas for shallow gas well control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bourgoyne, A.T.; Kelly, O.A.; Sandoz, C.L.

1996-06-01

Flow from an unexpected shallow gas sand is one of the most difficult well control problems faced by oil and gas well operators during drilling operations. Current well control practice for bottom-supported marine rigs usually calls for shutting in the well when a kick is detected, if sufficient casing has been set to keep any flow underground. However, when shallow gas is encountered, casing may not be set deep enough to keep the underground flow from broaching to surface near the platform foundations. Once the flow reaches surface, craters are sometimes formed which can lead to loss of the rigmore » and associated marine structures. This short article overviews an ongoing study by Louisiana State University of the breakdown resistance of shallow marine sediments, using leak-off test data and geotechnical reports provided by Unocal. Such study is important for improving the characterization of shallow marine sediments to allow more reliable shallow casing designs, as the authors will conclude. This study has already proven that sediment failure mechanisms that lead to cratering have been poorly understood. In addition, there has been considerable uncertainty as to the best choices of well design parameters and well control contingency plans that will minimize risks associated with a shallow gas flow.« less

Dispersion, Speciation, and Pollution Assessment of Heavy Metals Pb and Zn in Surface Sediment from Disturbed Ecosystem of Jeneberang Waters

NASA Astrophysics Data System (ADS)

Najamuddin; Surahman

2017-10-01

Surface sediments were collected from seventeen stations in Jeneberang waters (riverine, estuarine, and marine). Lead (Pb) and zinc (Zn) concentrations were determined by atomic absorption spectrometry, and the speciation of metals was obtained by a sequential extraction procedure. Dispersion of Pb and Zn were found higher in the riverine and marine samples than the estuarine samples. Following speciation, the metals were found similar composition of fraction in the riverine and estuarine samples but any different in the marine samples. The results indicated that there is a change of dispersion pattern and speciation composition of metals due to the presence of the dam that lies at the boundary between the estuary and the river. The toxicity unit was indicated low toxicity level; pollution level was in weakly to moderately polluted while the aquatic environment risk attributed were no risky to light risk.

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

PubMed

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

2016-02-15

To date, the longevity of plastic litter at the sea floor is poorly constrained. The present study compares colonization and biodegradation of plastic bags by aerobic and anaerobic benthic microbes in temperate fine-grained organic-rich marine sediments. Samples of polyethylene and biodegradable plastic carrier bags were incubated in natural oxic and anoxic sediments from Eckernförde Bay (Western Baltic Sea) for 98 days. Analyses included (1) microbial colonization rates on the bags, (2) examination of the surface structure, wettability, and chemistry, and (3) mass loss of the samples during incubation. On average, biodegradable plastic bags were colonized five times higher by aerobic and eight times higher by anaerobic microbes than polyethylene bags. Both types of bags showed no sign of biodegradation during this study. Therefore, marine sediment in temperate coastal zones may represent a long-term sink for plastic litter and also supposedly compostable material. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cable Bacteria in Freshwater Sediments

PubMed Central

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

2015-01-01

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

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

PubMed

Massana, Ramon; Gobet, Angélique; Audic, Stéphane; Bass, David; Bittner, Lucie; Boutte, Christophe; Chambouvet, Aurélie; Christen, Richard; Claverie, Jean-Michel; Decelle, Johan; Dolan, John R; Dunthorn, Micah; Edvardsen, Bente; Forn, Irene; Forster, Dominik; Guillou, Laure; Jaillon, Olivier; Kooistra, Wiebe H C F; Logares, Ramiro; Mahé, Frédéric; Not, Fabrice; Ogata, Hiroyuki; Pawlowski, Jan; Pernice, Massimo C; Probert, Ian; Romac, Sarah; Richards, Thomas; Santini, Sébastien; Shalchian-Tabrizi, Kamran; Siano, Raffaele; Simon, Nathalie; Stoeck, Thorsten; Vaulot, Daniel; Zingone, Adriana; de Vargas, Colomban

2015-10-01

Although protists are critical components of marine ecosystems, they are still poorly characterized. Here we analysed the taxonomic diversity of planktonic and benthic protist communities collected in six distant European coastal sites. Environmental deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) from three size fractions (pico-, nano- and micro/mesoplankton), as well as from dissolved DNA and surface sediments were used as templates for tag pyrosequencing of the V4 region of the 18S ribosomal DNA. Beta-diversity analyses split the protist community structure into three main clusters: picoplankton-nanoplankton-dissolved DNA, micro/mesoplankton and sediments. Within each cluster, protist communities from the same site and time clustered together, while communities from the same site but different seasons were unrelated. Both DNA and RNA-based surveys provided similar relative abundances for most class-level taxonomic groups. Yet, particular groups were overrepresented in one of the two templates, such as marine alveolates (MALV)-I and MALV-II that were much more abundant in DNA surveys. Overall, the groups displaying the highest relative contribution were Dinophyceae, Diatomea, Ciliophora and Acantharia. Also, well represented were Mamiellophyceae, Cryptomonadales, marine alveolates and marine stramenopiles in the picoplankton, and Monadofilosa and basal Fungi in sediments. Our extensive and systematic sequencing of geographically separated sites provides the most comprehensive molecular description of coastal marine protist diversity to date. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Deltaic sedimentation and stratigraphic sequences in post-orogenic basins, Western Greece

NASA Astrophysics Data System (ADS)

Piper, David J. W.; Kontopoulos, N.; Panagos, A. G.

1988-03-01

Post-orogenic basin sediments in the gulfs of Corinth, Patras and Amvrakia, on the western coast of Greece, occur in four tectonic settings: (1) true graben; (2) simple and complex half graben; (3) shallow half graben associated with the high-angel surface traces of thrust faults; and (4) marginal depressions adjacent to graben in which sediment loading has occurred. Late Quaternary facies distribution has been mapped in all three basins. Sea level changes, interacting with the apparently fortuitous elevation of horsts at basin margins, result in a complex alternation of well-mixed marine, stratified marine, brackish and lacustrine facies. Organic carbon contents of muds are high in all but the well-mixed marine facies. Basin margin slope is the most important determinant of facies distribution. The steep slopes of the Gulf of Corinth half graben result in fan-deltas which deliver coarse sediments in turbidity currents to the deep basin floor. Where gradients are reduced by marginal downwarping (Gulf of Patras) or on the gentle slopes of thrust-related half graben (Gulf of Amvrakia) coarse sediments are trapped on the subaerial delta or the coastal zone, and the fine sediment reaching the basin floor appears derived mainly from muddy plumes during winter floods.

Presence of Nitrate-Accumulating Sulfur Bacteria and Their Influence on Nitrogen Cycling in a Shallow Coastal Marine Sediment

PubMed Central

Sayama, Mikio

2001-01-01

Nitrate flux between sediment and water, nitrate concentration profile at the sediment-water interface, and in situ sediment denitrification activity were measured seasonally at the innermost part of Tokyo Bay, Japan. For the determination of sediment nitrate concentration, undisturbed sediment cores were sectioned into 5-mm depth intervals and each segment was stored frozen at −30°C. The nitrate concentration was determined for the supernatants after centrifuging the frozen and thawed sediments. Nitrate in the uppermost sediment showed a remarkable seasonal change, and its seasonal maximum of up to 400 μM was found in October. The directions of the diffusive nitrate fluxes predicted from the interfacial concentration gradients were out of the sediment throughout the year. In contrast, the directions of the total nitrate fluxes measured by the whole-core incubation were into the sediment at all seasons. This contradiction between directions indicates that a large part of the nitrate pool extracted from the frozen surface sediments is not a pore water constituent, and preliminary examinations demonstrated that the nitrate was contained in the intracellular vacuoles of filamentous sulfur bacteria dwelling on or in the surface sediment. Based on the comparison between in situ sediment denitrification activity and total nitrate flux, it is suggested that intracellular nitrate cannot be directly utilized by sediment denitrification, and the probable fate of the intracellular nitrate is hypothesized to be dissimilatory reduction to ammonium. The presence of nitrate-accumulating sulfur bacteria therefore may lower nature's self-purification capacity (denitrification) and exacerbate eutrophication in shallow coastal marine environments. PMID:11472923

Distribution and ecological risk of organic pollutants in the sediments and seafood of Yangtze Estuary and Hangzhou Bay, East China Sea.

PubMed

Adeleye, Adedayo O; Jin, Haiyan; Di, Yanan; Li, Donghao; Chen, Jianfang; Ye, Ying

2016-01-15

A wide variety of persistent organic pollutants (POPs) in the surface marine sediments and seafood from four geographic areas of the East China Sea were investigated. The POP concentrations were analyzed and their possible ecotoxicological risks assessed. The total concentrations of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) in the sediments were found to be ND-22.40, ND-5.10, 32.10-171.70, and 0.60-63.00 ng/g dry weight (dw), respectively. Low-chlorinated biphenyl congeners and HCHs were predominantly found at the Hangzhou Bay and Yangtze River areas. The sediment ecotoxicological risk was assessed, indicating the toxic effect of PCBs and DDTs on benthic organisms. In marine organisms of economic importance, the concentration of total PAHs, PCBs, and organochlorine pesticides (OCPs) ranged from 43.20 to 291.20, 2.60 to 96.20, and 12.70 to 235.20 μg/kg dw, respectively. The bioaccumulation in marine organisms did not pose a significant health risk to consumers. As indicated by the POP residues in both marine sediments and organisms, POPs were persistent over time, posing a long-term risk to the local ecosystem and human health via the food chain. Copyright © 2015 Elsevier B.V. All rights reserved.

Rapid bacterial colonization of low-density polyethylene microplastics in coastal sediment microcosms.

PubMed

Harrison, Jesse P; Schratzberger, Michaela; Sapp, Melanie; Osborn, A Mark

2014-09-23

Synthetic microplastics (≤5-mm fragments) are emerging environmental contaminants that have been found to accumulate within coastal marine sediments worldwide. The ecological impacts and fate of microplastic debris are only beginning to be revealed, with previous research into these topics having primarily focused on higher organisms and/or pelagic environments. Despite recent research into plastic-associated microorganisms in seawater, the microbial colonization of microplastics in benthic habitats has not been studied. Therefore, we employed a 14-day microcosm experiment to investigate bacterial colonization of low-density polyethylene (LDPE) microplastics within three types of coastal marine sediment from Spurn Point, Humber Estuary, U.K. Bacterial attachment onto LDPE within sediments was demonstrated by scanning electron microscopy and catalyzed reporter deposition fluorescence in situ hybridisation (CARD-FISH). Log-fold increases in the abundance of 16S rRNA genes from LDPE-associated bacteria occurred within 7 days with 16S rRNA gene numbers on LDPE surfaces differing significantly across sediment types, as shown by quantitative PCR. Terminal-restriction fragment length polymorphism (T-RFLP) analysis demonstrated rapid selection of LDPE-associated bacterial assemblages whose structure and composition differed significantly from those in surrounding sediments. Additionally, T-RFLP analysis revealed successional convergence of the LDPE-associated communities from the different sediments over the 14-day experiment. Sequencing of cloned 16S rRNA genes demonstrated that these communities were dominated after 14 days by the genera Arcobacter and Colwellia (totalling 84-93% of sequences). Attachment by Colwellia spp. onto LDPE within sediments was confirmed by CARD-FISH. These results demonstrate that bacteria within coastal marine sediments can rapidly colonize LDPE microplastics, with evidence for the successional formation of plastisphere-specific bacterial assemblages. Although the taxonomic compositions of these assemblages are likely to differ between marine sediments and the water column, both Arcobacter and Colwellia spp. have previously been affiliated with the degradation of hydrocarbon contaminants within low-temperature marine environments. Since hydrocarbon-degrading bacteria have also been discovered on plastic fragments in seawater, our data suggest that recruitment of hydrocarbonoclastic bacteria on microplastics is likely to represent a shared feature between both benthic and pelagic marine habitats.

Pleistocene to Holocene contrasts in organic matter production and preservation on the California continental margin

USGS Publications Warehouse

Dean, W.E.; Gardner, J.V.

1998-01-01

Organic matter in sediments from cores collected from the upper continental slope (200-2700 m) off California and southern Oregon shows marked differences in concentration and marine character between the last glacial interval (ca. 24-10 ka) and either Holocene time or last interstadial (oxygen isotope stage 3, ca. 60-24 ka). In general, sediments deposited during Holocene time and stage 3 contain higher amounts of marine organic matter than those deposited during the last glacial interval, and this contrast is greatest in cores collected off southern California. The most profound differences in stage 3 sediments are between predominantly bioturbated sediments and occasional interbeds of laminated sediments. The sediments are from cores collected within the present oxygen minimum zone on the upper continental slope from as far north as the Oregon-California border to as far south as Point Conception. These upper Pleistocene laminated sediments contain more abundant hydrogen-rich (type II) marine algal organic matter than even surface sediments that have large amounts of nonrefractory organic matter. The stable carbon-isotopic composition of the organic matter does not change with time between bioturbated and laminated sediments, indicating that the greater abundance of type II organic matter in the laminated sediments is not due to a change in source but rather represents a greater degree of production and preservation of marine organic matter. The presence of abundant, well-preserved organic matter supports the theory that the oxygen minimum zone in the northeastern Pacific Ocean was more intense, and possibly anoxic, during late Pleistocene time as a result of increased coastal upwelling that enhanced algal productivity.

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

NASA Astrophysics Data System (ADS)

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 lander images; and widespread minor structures with neither terrestrial volcanic analogues nor plausible volcanic explanations. Broad tracts of polygonal reticulations 100 m to 5 km in diameter have dimensional and geometric terrestrial analogues in the polygonal faulting shown by 3-D reflection-seismic surveys of dewatered fine-grained sediments in marine basins. Impact-comminuted basaltic crust may dominate the fine sediment. Vast numbers of small low so-called shield volcanoes have geometric analogues in terrestrial mud volcanoes, not magmatic constructs. Less than half of the 1000 small misnamed pristine craters, the only venusian craters accepted by all as of impact origin, in fact are pristine. The rest are variably eroded, their craters partly filled by sediments that often display polygonal faulting, and their aprons partly covered by sediments of surrounding plains. All gradations are displayed between these structures and the more modified but otherwise similar structures from which they are arbitrarily and inconsistently separated. Lunar analogy dates the thousands of large venusian craters, 300-2000 km in rim diameter, as older than 3.8 Ga. Marine sedimentation began before late-stage accretion was complete. The nominally pristine craters are commonly assumed to be younger than 1 Ga but may go back to 3.8 Ga. Venusian oceans persisted long after that, without stillstands sufficient for development of global shorelines and shelves, before complete greenhouse evaporation, deep desiccation, and top-down metamorphism of sediments.

Study on the sorption behaviour of estrone on marine sediments.

PubMed

Zhang, Jing; Yang, Gui-Peng; Li, Quan; Cao, Xiaoyan; Liu, Guangxing

2013-11-15

The sorption behaviour of estrone (E1) on marine sediments treated by different methods was systematically investigated. About 22 h was required for sorption equilibrium of E1. Sorption isotherms of E1 were well fitted with Freundlich model. The sorption behaviour of E1 on HCl-treatment and H2O-treatment sediments related significantly with the sediment organic carbon contents. Additionally, clay minerals and surface areas of sediments played dominant roles in the sorption of E1 on H2O2-treatment sediments. Some external factors which could affect sorption behaviour of E1 were also investigated. Our results showed that the sorption capacity of E1 on the sediments increased with the increasing concentrations of cationic surfactant cetyltrimethylammonium bromide (CTAB), nonionic surfactant polyoxyethylene (80) sorbitan esters (Tween 80) and salinity of seawater. In contrast, the sorption capacity of E1 decreased with the increasing concentration of anionic surfactant sodium dodecylbenzene sulfonate (SDBS), pH value and temperature of seawater. Copyright © 2013 Elsevier Ltd. All rights reserved.

Decline of radionuclides in the nearshore environment following nuclear reactor closure: A U.K. case study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cundy, A.B.; Croudace, I.W.; Warwick, P.E.

1999-09-01

Radioactive discharges from nuclear facilities are frequently made into the marine environment and their fate during and after cessation of discharges is a matter of interest and concern. This study examines the decline of the radionuclides {sup 60} and {sup 65}Zn along the southern UK. coast, over the per 1988--1998, following the closure of the steam-generating heavy water (SGHW) reactor at AEA Winfrith, Dorset, UK. {sup 60}Co and {sup 65}Zn (and other activation products such as {sup 63}Ni and {sup 55}Fe) were widely dispersed in the marine environment off the central south coast of England, due to authorized releases frommore » AEA Winfrith. Significant interaction occurred with clay-rich sediments and biota. A general exponential decline in {sup 60}Co activities (and in {sup 65}Zn activity) is found in intertidal mudflat sediments, seaweed and marine fauna in different areas along the south coast following closure of the reactor in 1990. Effective half-lives are determined which vary from 1 to 4 years in surface sediments ({sup 60}Co only), 1--4 years in seaweed and 0.5--2.5 years in crustaceans, bivalves and molluscs. Physical mixing and bioturbation largely control the rate at which {sup 60}Co declines in surface sediments. Both {sup 60}Co and {sup 65}Zn show a relatively slow rate of decline in seaweed and in marine fauna, showing that even after the virtual cessation of discharge from nuclear facilities, contamination of these organisms may persist for a number of years, albeit at reduced activities. Reasons for this persistence are likely to include absorption of radionuclides from sediment, and release and recycling of radionuclides via breakdown of contaminated organic material.« less

Rapid Redox Signal Transmission by “Cable Bacteria” beneath a Photosynthetic Biofilm

PubMed Central

Meysman, F. J. R.

2014-01-01

Recently, long filamentous bacteria, belonging to the family Desulfobulbaceae, were shown to induce electrical currents over long distances in the surface layer of marine sediments. These “cable bacteria” are capable of harvesting electrons from free sulfide in deeper sediment horizons and transferring these electrons along their longitudinal axes to oxygen present near the sediment-water interface. In the present work, we investigated the relationship between cable bacteria and a photosynthetic algal biofilm. In a first experiment, we investigated sediment that hosted both cable bacteria and a photosynthetic biofilm and tested the effect of an imposed diel light-dark cycle by continuously monitoring sulfide at depth. Changes in photosynthesis at the sediment surface had an immediate and repeatable effect on sulfide concentrations at depth, indicating that cable bacteria can rapidly transmit a geochemical effect to centimeters of depth in response to changing conditions at the sediment surface. We also observed a secondary response of the free sulfide at depth manifest on the time scale of hours, suggesting that cable bacteria adjust to a moving oxygen front with a regulatory or a behavioral response, such as motility. Finally, we show that on the time scale of days, the presence of an oxygenic biofilm results in a deeper and more acidic suboxic zone, indicating that a greater oxygen supply can enable cable bacteria to harvest a greater quantity of electrons from marine sediments. Rapid acclimation strategies and highly efficient electron harvesting are likely key advantages of cable bacteria, enabling their success in high sulfide generating coastal sediments. PMID:25416774

Rapid redox signal transmission by "Cable Bacteria" beneath a photosynthetic biofilm.

PubMed

Malkin, S Y; Meysman, F J R

2015-02-01

Recently, long filamentous bacteria, belonging to the family Desulfobulbaceae, were shown to induce electrical currents over long distances in the surface layer of marine sediments. These "cable bacteria" are capable of harvesting electrons from free sulfide in deeper sediment horizons and transferring these electrons along their longitudinal axes to oxygen present near the sediment-water interface. In the present work, we investigated the relationship between cable bacteria and a photosynthetic algal biofilm. In a first experiment, we investigated sediment that hosted both cable bacteria and a photosynthetic biofilm and tested the effect of an imposed diel light-dark cycle by continuously monitoring sulfide at depth. Changes in photosynthesis at the sediment surface had an immediate and repeatable effect on sulfide concentrations at depth, indicating that cable bacteria can rapidly transmit a geochemical effect to centimeters of depth in response to changing conditions at the sediment surface. We also observed a secondary response of the free sulfide at depth manifest on the time scale of hours, suggesting that cable bacteria adjust to a moving oxygen front with a regulatory or a behavioral response, such as motility. Finally, we show that on the time scale of days, the presence of an oxygenic biofilm results in a deeper and more acidic suboxic zone, indicating that a greater oxygen supply can enable cable bacteria to harvest a greater quantity of electrons from marine sediments. Rapid acclimation strategies and highly efficient electron harvesting are likely key advantages of cable bacteria, enabling their success in high sulfide generating coastal sediments. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Detection of recycled marine sediment components in crater lake fluids using 129I

NASA Astrophysics Data System (ADS)

Fehn, U.; Snyder, G. T.; Varekamp, J. C.

2002-06-01

Crater lakes provide time-integrated samples of volcanic fluids, which may carry information on source components. We tested under what circumstances 129I concentrations can be used for the detection of a signal derived from the recycling of marine sediments in subduction zone magmatism. The 129I system has been successfully used to determine origin and pathways in other volcanic fluids, but the application of this system to crater lakes is complicated by the presence of anthropogenic 129I, related to recent nuclear activities. Results are reported from four crater lakes, associated with subducting crust varying in age between 23 and 98 Ma. The 129I/I ratios determined for Copahue, Argentina, (129I/I=700×10-15) and White Island, New Zealand, (129I/I=284×10-15) demonstrate the presence of iodine in the crater lakes that was derived from recycled marine sediments. A comparison to the ages of the subducted sediments in these two cases indicates that the ratios likely reflect iodine remobilization from the entire sediment column that was undergoing subduction. While the 129I signals in Poás and Rincón de la Vieja, Costa Rica also demonstrate the presence of recycled iodine, the relatively high percentage of meteoric water in these lakes prevents a reliable determination of source ages. The observed high concentrations of iodine and 129I/I ratios substantially below current surface values strongly argue for the presence of recycled marine components in the arc magmas of all four cases. Components from subducted marine sediments can be quantified and related to specific parts of the sediment column in cases where the iodine concentration in the lake waters exceeds 5 μM.

Environmental Radioactivity Study in Surface Sediments of Guacanayabo Gulf (Cuba)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reyes, H.; Rizo, O. Diaz; Bernal, J. L.

Sediment samples have been collected in the Guacanayabo gulf located in the southeast Cuba, to determinate the radioactivity levels of {sup 210}Pb, {sup 234}Th, {sup 214}Pb, {sup 137}Cs, {sup 232}Th and {sup 40}K using Low-Background Gamma Spectrometry and to evaluate its impact in the habitat of important marine species for fishery industry. The obtained results show the lowest radioactivity levels determined in Cuban marine environments. The species capture declination in the last years is not originated by radioactive pollution of the zone.

VARIATIONS IN MINERAL MATTER CONTENT OF A PEAT DEPOSIT IN MAINE RESTING ON GLACIO-MARINE SEDIMENTS.

USGS Publications Warehouse

Cameron, Cornelia C.; Schruben, Paul

1983-01-01

The Great Heath, Washington County, Maine, is an excellent example of a multidomed ombrotrophic peatland resting on a gently undulating surface of glacio-marine sediments and towering above modern streams. A comprehensive study sponsored by the Geological Survey of Maine in cooperation with the U. S. Geological Survey included preparation of a contoured surficial geology map on which are located 81 core sites. Eight cross sections accompany the map showing occurrence and thickness of three types of organic material and locations of cored sample analyses. Refs.

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

NASA Astrophysics Data System (ADS)

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

2013-12-01

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

The Late-Quaternary climatic signal recorded in a deep-sea turbiditic levee (Rhône Neofan, Gulf of Lions, NW Mediterranean): palynological constraints

NASA Astrophysics Data System (ADS)

Beaudouin, Célia; Dennielou, Bernard; Melki, Tarek; Guichard, François; Kallel, Nejib; Berné, Serge; Huchon, Agnès

2004-11-01

Siliciclastic turbidites represent huge volumes of sediments, which are of particular significance for (1) petroleum researchers, interested in their potential as oil reservoirs and (2) sedimentologists, who aim at understanding sediment transport processes from continent to deep-basins. An important challenge when studying marine turbidites has been to establish a reliable chronology for the deposits. Indeed, conventional marine proxies applied to hemipelagic sediments are often unreliable in detrital clays. In siliciclastic turbidites, those proxies can be used only in hemipelagic intervals, providing a poor constraint on their chronology. In this study, we have used sediments from the Rhône Neofan (NW Mediterranean Sea) to demonstrate that pollen grains can provide a high-resolution chronostratigraphical framework for detrital clays in turbidites. Vegetation changes occurring from the end of Marine Isotopic Stage 3 to the end of Marine Isotopic Stage 2 (from ˜30 to ˜18 ka cal. BP) are clearly recorded where other proxies have failed previously, mainly because the scarcity of foraminifers in these sediments prevented any continuous Sea Surface Temperature (SST) record and radiocarbon dating to be obtained. We show also that the use of palynology in turbidite deposits is able to contribute to oceanographical and sedimentological purposes: (1) Pinus pollen grains can document the timing of sea-level rise, (2) the ratio between pollen grains transported from the continent via rivers and dinoflagellate cysts (elutriating) allows us to distinguish clearly detrital sediments from pelagic clays. Finally, taken together, all these tools show evidence that the Rhône River disconnected from the canyon during the sea-level rise and thus evidence the subsequent rapid starvation of the neofan at 18.5 ka cal. BP. Younger sediments are hemipelagic: the frequency of foraminifers allowed to date sediments with radiocarbon. First results of Sea Surface Temperature obtained on foraminifers are in good agreement with the dinoflagellate cysts climatic signal. Both provide information on the end of the deglaciation and the Holocene.

Distribution, Source, and Ecological Risk Assessment of Polycyclic Aromatic Hydrocarbons in Surface Sediment of Liaodong Bay, Northeast China

NASA Astrophysics Data System (ADS)

Xu, Shuang; Tao, Ping; Li, Yuxia; Guo, Qi; Zhang, Yan; Wang, Man; Jia, Hongliang; Shao, Mihua

2018-01-01

Sixteen polycyclic aromatic hydrocarbons (PAHs) were determined in surface sediments from Liaodong Bay, northeast China. The concentration levels of total PAHs (Σ16PAHs) in sediment were 11.0˜249.6 ng·g-1 dry weight (dw), with a mean value of 89.9 ng·g-1 dry weight (dw). From the point of the spatial distribution, high PAHs levels were found in the western areas of Liaodong Bay. In the paper, sources of PAHs were investigated by diagnostic ratios, which indicated that pyrogenic sources were the main sources of PAHs in the sediment of Liaodong Bay. Therefore, selected PAH levels in sediments were compared with Sediments Quality Guidelines (ERM-ERL indexes) for evaluation probable toxic effects on marine organism.

An Ocean Basin of Dirt? Using Molecular Biomarkers and Radiocarbon to Identify Organic Carbon Sources and their Preservation in the Arctic Ocean

NASA Astrophysics Data System (ADS)

Harvey, H.; Belicka, L. L.

2005-12-01

In the modern Arctic Ocean, primary production in waters over the broad continental shelves and under ice contributes an estimated 250 Mt/yr of POC to Arctic waters. The delivery of terrestrial material from large rivers, ice transport and through coastal erosion adds at least an additional 12 Mt/yr of POC. Although the marine organic carbon signal in Arctic Ocean exceeds that of terrestrial carbon by an order or magnitude or more, recent evidence suggests that this balance is not maintained and significant fractions of terrestrial carbon is preserved in sediments. Using an integrated approach combining lipid biomarkers and radiocarbon dating in particles and sediments, the process of organic carbon recycling and historical changes in its sources and preservation has been examined. A suite of lipid biomarkers in particles and sediments of western Arctic shelves and basins were measured and principle components analysis (PCA) used to allow a robust comparison among the 120+ individual compounds to assign organic sources and relative inputs. Offshore particles from the chlorophyll maximum contained abundant algal markers (e.g. 20:5 and 22:6 FAMEs), low concentrations of terrestrial markers (amyrins and 24-ethylcholest-5-en-3b-ol), and reflected modern 14C values. Particles present in deeper halocline waters also reflect marine production, but a portion of older, terrestrial carbon accompanies the sinking of the spring bloom. Surface and deeper sediments of basins contain older organic carbon and low concentrations of algal biomarkers, suggesting that marine carbon produced in surface waters is rapidly recycled. Taken together, these observations suggest that marine derived organic matter produced in shallow waters fuels carbon cycling, but relatively small amounts are preserved in sediments. As a result, the organic carbon preserved in sediments contrasts sharply to that typically observed in lower latitudes, with an increasing terrestrial signature with distance from land and potential for significant changes under a changing climate.

Muddy marine sediments are gels

NASA Astrophysics Data System (ADS)

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.

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

USGS Publications Warehouse

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

1999-01-01

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

Biogenic disturbance determines invasion success in a subtidal soft-sediment system.

PubMed

Lohrer, Andrew M; Chiaroni, Luca D; Hewitt, Judi E; Thrush, Simon F

2008-05-01

Theoretically, disturbance and diversity can influence the success of invasive colonists if (1) resource limitation is a prime determinant of invasion success and (2) disturbance and diversity affect the availability of required resources. However, resource limitation is not of overriding importance in all systems, as exemplified by marine soft sediments, one of Earth's most widespread habitat types. Here, we tested the disturbance-invasion hypothesis in a marine soft-sediment system by altering rates of biogenic disturbance and tracking the natural colonization of plots by invasive species. Levels of sediment disturbance were controlled by manipulating densities of burrowing spatangoid urchins, the dominant biogenic sediment mixers in the system. Colonization success by two invasive species (a gobiid fish and a semelid bivalve) was greatest in plots with sediment disturbance rates < 500 cm(3) x m(-2) x d(-1), at the low end of the experimental disturbance gradient (0 to > 9000 cm(3) x m(-2) x d(-1)). Invasive colonization declined with increasing levels of sediment disturbance, counter to the disturbance-invasion hypothesis. Increased sediment disturbance by the urchins also reduced the richness and diversity of native macrofauna (particularly small, sedentary, surface feeders), though there was no evidence of increased availability of resources with increased disturbance that would have facilitated invasive colonization: sediment food resources (chlorophyll a and organic matter content) did not increase, and space and access to overlying water were not limited (low invertebrate abundance). Thus, our study revealed the importance of biogenic disturbance in promoting invasion resistance in a marine soft-sediment community, providing further evidence of the valuable role of bioturbation in soft-sediment systems (bioturbation also affects carbon processing, nutrient recycling, oxygen dynamics, benthic community structure, and so on.). Bioturbation rates are influenced by the presence and abundance of large burrowing species (like spatangoid urchins). Therefore, mass mortalities of large bioturbators could inflate invasion risk and alter other aspects of ecosystem performance in marine soft-sediment habitats.

Distribution of short chain chlorinated paraffins in marine sediments of the East China Sea: influencing factors, transport and implications.

PubMed

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.

Molybdenum Cycling in Upwelling Sediments: An Example from Namibian Margin Sediments

NASA Astrophysics Data System (ADS)

Arnold, G. L.; Goldhammer, T.; Formolo, M.; Brunner, B.; Ferdelman, T.

2008-12-01

The paleo-redox application of molybdenum (Mo) isotopes is strongly tied to our knowledge of the modern marine Mo cycle. Elemental mass balance indicates that ~47% of the Mo supplied to the oceans is removed to deep sea sediments, leaving the remaining Mo to "near-shore" reducing sediments (1). The Black Sea is likely the best studied reducing environment with regards to Mo isotopes, yet accounts for only a small fraction of the Mo mass balance. The accumulation of Mo in continental margin sediments has been recently re-assessed and may account for a larger fraction of the marine Mo reservoir than previously thought (2). In the presence of sulfide, the molybdate anion is transformed, by the replacement of oxygen with sulfur, to particle reactive oxy-thiomolybdates (3). This is often cited as the mechanism by which Mo removal proceeds in the Black Sea where sulfide concentrations in the water are high. In contrast, in continental margin settings, the removal mechanism is poorly understood, and the extent to which sulfur cycling plays a role remains un-quantified. To better understand removal/cycling processes in a continental margin setting, where sulfide may only be present in the pore waters and not in the water column, Mo was studied in an array of marine settings off the Namibian coast. Surface sediments were collected across a transect from near-shore/high productivity to deep water/low productivity sediments. These sediments were incubated in bag experiments to study the relationship between sulfur and Mo cycling. Molybdenum concentrations in the Namibian sediments range from detrital values at the lowest productivity site to 25 ppm in surface sediments with high productivity. Preliminary results allude to a correlation between sulfate reduction rates and Mo accumulation in these sediments. Detailed studies of Mo, Mo isotopes, other trace metals, and sulfur investigations from both sediment cores and bag experiments will be presented. (1)Bertine and Turekian (1973), Geochim. Cosmochim. Acta 87, 1415. (2)McManus et al. (2006), Geochim. Cosmochim. Acta 70, 4643. (3)Erickson and Helz (2000) Geochim. Cosmochim. Acta 64, 1149.

Characterizing Cretaceous Glaciation Events: K-Ar Ages of Southern Ocean Sediments

NASA Astrophysics Data System (ADS)

Wright, M. A.; Hemming, S. R.; Barbeau, D. L.; Torfstein, A.; Pierce, E. L.; Williams, T.; McManus, J. F.; Gombiner, J.

2012-12-01

Evidence from paleosols and carbonate weathering models suggest that the Late Cretaceous had a supergreenhouse climate due to atmospheric CO2 concentrations two to four times greater than modern levels, tropical sea surface temperatures exceeding 35°C, and high-latitude temperatures exceeding 20°C. Despite this warmth, the Late Cretaceous was apparently punctuated by large (>25 m) and rapid (<<1 million year) sea-level changes, as recorded by marginal marine stratigraphic architectures and pelagic stable isotope compositions. The magnitude and tempo of these changes suggest a glacio-eustatic control, presumably from the growth and decay of continental ice sheets on Antarctica. Because continental glaciation tends to increase the weathering of bedrock and production of sediment delivered to the oceans, circum-Antarctic marine sediment flux would be expected to increase during periods of glaciation. In order to identify a Late Cretaceous glaciation signal from such marine records, we must first constrain the compositional signal of continental detritus in marine sediments. Here we report the results of downcore K-Ar analysis of the terrigenous sediments of Quaternary Weddell Sea cores PS1170-1 and PS1388-3 in order to identify the compositional signature of continent-derived detritus deposited in the Weddell Sea during a known glacial period. Further, we use our K-Ar analyses of circum-Antarctic Quaternary sediment cores to pinpoint potential sediment source areas. Having constrained this glaciation signal, we also present preliminary K-Ar and Sm-Nd analysis of the Campanian-Maastrictian boundary event (69 Ma) at Ocean Drilling Project site 690C to assess the controversial hypothesis of Late Cretaceous glaciation of Antarctica.

Inorganic geochemistry of surface sediments of the Ebro shelf and slope, northwestern Mediterranean

USGS Publications Warehouse

Gardner, J.V.; Dean, W.E.; Alonso, B.

1990-01-01

Distributions of major, minor, and trace elements in surface sediment of the continental shelf and upper slope of the northeastern Spanish continental margin reflect the influences of discharge from the Ebro River and changes in eustatic sea levels. Multivariate factor analysis of sediment geochemistry was used to identify five groupings of samples (factors) on the shelf and slope. The first factor is an aluminosilicate factor that represents detrital clastic material. The second factor is a highly variable amount of excess SiO2 and probably represents a quartz residuum originating from winnowing of relict detrital sediments. A carbonate factor (Factor 3) has no positive correlation with other geochemical parameters but is associated with the sand-size fraction. The carbonate in these sediments consists of a mixture of biogenic calcite and angular to subangular detrital grains. Organic carbon is associated with the aluminosilicate factor (Factor 1) but also factors out by itself (Factor 4); this suggests that there may be two sources of organic matter, terrestrial and marine. The fifth factor comprises upper slope sediments that contain high concentrations of manganese. The most likely explanation for these high manganese concentrations is precipitation of Mn oxyhydroxides at the interface between Mn-rich, oxygen-deficient, intermediate waters and oxygenated surface waters. During eustatic low sea levels of the glacial Pleistocene, the Ebro Delta built across the outer continental shelf and deposited sediment with fairly high contents of organic carbon and continental components. The period of marine transgression from eustatic low (glacial) to eustatic high (interglacial) sea levels was characterized by erosion of the outer shelf delta and surficial shelf sediments and the transport of sediment across the slope within numerous canyons. Once eustatic high sea level was reached, delta progradation resumed on the inner shelf. Today, coarse-grained sediment (silt and sand) is transported to the continental shelf by Ebro River and is distributed along the inner shelf by currents generated by dominant northeasterly winds. Clay-size material is deposited on the mid- and outer-shelf. However, erosion and delta progradation during the last glacial period, and fine-grained Holocene sedimentation, have probably produced a distribution of sediment on a diachronous surface. ?? 1990.

A twisted tale - how biocorrosion communities yield new insight on the distribution of marine iron-oxidizing bacteria

NASA Astrophysics Data System (ADS)

McBeth, J. M.; Emerson, D.

2011-12-01

Microbiologically influenced corrosion (MIC) of mild steel is a complex process involving biogeochemical interactions between bacteria, steel surfaces, and biogenic and abiotically produced minerals. The role of neutrophilic iron-oxidizing bacteria (FeOB) in this process is poorly understood, and surprisingly, little is known about the microbial ecology of corroding steel in marine environments. Based on previous work (McBeth et al 2011), we hypothesized that coastal sediments act as reservoirs for marine FeOB of the candidatus class 'Zetaproteobacteria', and that these bacteria will colonize and become numerically abundant on steel surfaces. To test this, mild steel coupons were incubated in a salt marsh and sampled over 40 days in summer 2010. DNA extracted from the steel surfaces was analyzed for overall bacterial diversity by pyrosequencing of the V4 variable region of the 16S rRNA gene, and relevant communities were quantified using qPCR. The qPCR analyses were done using 16S primers specific to prokaryotes (Takai & Horikoshi 2000) and Zetaproteobacteria (Kato et al 2009), and a dsrA gene specific primer (Ben-Dov et al 2007) to assess the population of sulfate-reducing bacteria (SRB). Pyrosequencing data analyses showed Zetaproteobacteria were present on steel samples throughout the incubations and were also present in adjacent sediments; however, the diversity of Zetaproteobacteria was lower on the steel in comparison with sediments, indicating specific populations were enriched on the steel coupons. Iron oxyhydroxide stalk biosignatures were observed on the steel and in enrichment cultures, evidence that the Zetaproteobacteria identified using molecular techniques were likely FeOB. Relatives of the H2-oxidizing genus Hydrogenophaga and members of the family Rhodobacterales were also identified as important members of the biocorrosion community and were present both on steel and in sediments. The diversity of these organisms on steel surfaces increased with incubation time. The populations assessed with qPCR remained fairly constant in the sediments during the course of the study. The number of Zetaproteobacteria in the sediments was approximately 10 fold lower than the SRB numbers. In contrast, the proportion of Zetaproteobacteria present on the steel increased rapidly over the first 10 days, exceeding the copy numbers present in the sediment by an order of magnitude. The SRB numbers on the steel were 10 fold lower than in sediments during the first days of incubation, but increased with time to near the sediment numbers of SRB at 40 days. The proportion of SRB in sediments was relatively high and constant. This work illustrates that coastal sediments may be a hitherto unrecognized reservoir for Zetaproteobacteria who, though numerically low in the sediment, can quickly colonize environments where free Fe(II) is abundant.

Complex community of nitrite-dependent anaerobic methane oxidation bacteria in coastal sediments of the Mai Po wetland by PCR amplification of both 16S rRNA and pmoA genes.

PubMed

Chen, Jing; Zhou, Zhichao; Gu, Ji-Dong

2015-02-01

In the present work, both 16S rRNA and pmoA gene-based PCR primers were employed successfully to study the diversity and distribution of n-damo bacteria in the surface and lower layer sediments at the coastal Mai Po wetland. The occurrence of n-damo bacteria in both the surface and subsurface sediments with high diversity was confirmed in this study. Unlike the two other known n-damo communities from coastal areas, the pmoA gene-amplified sequences in the present work clustered not only with some freshwater subclusters but also within three newly erected marine subclusters mostly, indicating the unique niche specificity of n-damo bacteria in this wetland. Results suggested vegetation affected the distribution and community structures of n-damo bacteria in the sediments and n-damo could coexist with sulfate-reducing methanotrophs in the coastal ecosystem. Community structures of the Mai Po n-damo bacteria based on 16S rRNA gene were different from those of either the freshwater or the marine. In contrast, structures of the Mai Po n-damo communities based on pmoA gene grouped with the marine ones and were clearly distinguished from the freshwater ones. The abundance of n-damo bacteria at this wetland was quantified using 16S rRNA gene PCR primers to be 2.65-6.71 × 10(5) copies/g dry sediment. Ammonium and nitrite strongly affected the community structures and distribution of n-damo bacteria in the coastal Mai Po wetland sediments.

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

PubMed

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

2008-06-01

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

Stratigraphy of a proposed wind farm site southeast of Block Island: Utilization of borehole samples, downhole logging, and seismic profiles

NASA Astrophysics Data System (ADS)

Sheldon, Dane P. H.

Seismic stratigraphy, sedimentology, lithostratigraphy, downhole geophysical logging, mineralogy, and palynology were used to study and interpret the upper 70 meters of the inner continental shelf sediments within a proposed wind farm site located approximately two to three nautical miles to the southeast of Block Island, Rhode Island. Core samples and downhole logging collected from borings drilled for geotechnical purposes at proposed wind turbine sites along with seismic surveys in the surrounding area provide the data for this study. Cretaceous coastal plain sediments that consist of non-marine to marine sand, silt, and clay are found overlying bedrock at a contact depth beyond the sampling depth of this study. The upper Cretaceous sediments sampled in borings are correlated with the Magothy/Matawan formations described regionally from New Jersey to Nantucket. An unconformity formed through sub-aerial, fluvial, marine, and glacial erosion marks the upper strata of the Cretaceous sediments separating them from the overlying deposits. The majority of Quaternary deposits overlying the unconformity represent the advance, pulsing, and retreat of the Laurentide ice sheet that reached its southern terminus in the area of Block Island approximately 25,000 to 21,000 years before present. The sequence consists of a basal glacial till overlain by sediments deposited by meltwater environments ranging from deltaic to proglacial lakefloor. A late Pleistocene to early Holocene unconformity marks the top of the glacial sequence and was formed after glacial retreat through fluvial and subaerial erosion/deposition. Overlying the glacial sequence are sediments deposited during the late Pleistocene and Holocene consisting of interbedded gravel, sand, silt, and clay. Sampling of these sediments was limited and surficial reflectors in seismic profiles were masked due to a hard bottom return. However, two depositional periods are interpreted as representing fluvial and estuarine/marine environments respectively. One sample recovered at five meters contained shell fragments within a gray fine to coarse sand possibly representing a shallow estuarine to marine environment. A coarse near surface deposit described but not recovered in all borings may represent a transgressive unconformity and resulting lag deposit however due to lack of sampling and seismic resolution in the upper 5 meters, the nature of this deposit is merely speculation. In areas where depth to the glacial surface increased, sediments ranging from sand to fine-grained silt and clay were encountered in borings. In summary, the upper 70 meters of the inner continental shelf section within the study site consists of unconsolidated sediments spanning three major depositional periods. Sediments derived from glacial activity represent the bulk of samples collected. The glacial sequences represent various depositional environments, although most samples are interpreted to be the product of glacial meltwater deposition with distribution determined by source as well as highs and lows present in the antecedent topography. Finely laminated (varved) sediment to the south of Block Island indicates the presence of proglacial lakes in the area during the time of glacial retreat. Overlying sediments represent environments ranging from fluvial to marine.

Calculating the Diffusive Flux of Persistent Organic Pollutants between Sediments and the Water Column on the Palos Verdes Shelf Superfund Site using Polymeric Passive Samplers

EPA Science Inventory

Passive samplers were used to determine water concentrations of persistent organic pollutants (POPs) in the surface sediments and near-bottom water of a marine Superfund site on the Palos Verdes Shelf, California, USA. Measured concentrations in the porewater and water column at...

Comparison of solid-phase and pore-water approaches for assessing the quality of marine and estuarine sediments

USGS Publications Warehouse

Carr, Robert Scott; Chapman, Duane C.

1992-01-01

As part of our continuing evaluation of the pore-water approach for assessing sediment quality, we made a series of side-by-side comparisons between the standard 10-day amphipod whole sediment test with the corophiid Grandidierella japonica and a suite of tests using pore water extracted from the same sediments. the pore-water tests evaluated were the sea urchin (Arbacia punctulata) sperm cell test and morphological development assay, the life-cycle test with the polychaete Dinophilus gyrociliatus, and acute exposures of red drum (Sciaenops ocellatus) embryo-larval stages. Sediment and surface microlayer samples were collected from contaminated sites. Whole-sediment, pore-water, and surface microlayer toxicity tests were performed. Pore-water toxicity tests were considerably more sensitive than the whole-sediment amphipod test, which is currently the most sensitive toxicity test now recommended for determining the acceptability of dredged material for open ocean disposal.

Contrasting effects of ecosystem engineering by the cordgrass Spartina maritima and the sandprawn Callianassa kraussi in a marine-dominated lagoon

NASA Astrophysics Data System (ADS)

Pillay, D.; Branch, G. M.; Dawson, J.; Henry, D.

2011-01-01

Ecosystem engineering by plants and animals significantly influences community structure and the physico-chemical characteristics of marine habitats. In this paper we document the contrasting effects of ecosystem engineering by the cordgrass Spartina maritima and the burrowing sandprawn Callianassa kraussi on physico-chemical characteristics, microflora, macrofaunal community structure and morphological attributes in the high shore intertidal sandflats of Langebaan Lagoon, a marine-dominated system on the west coast of South Africa. Comparisons were made at six sites in the lagoon within Spartina and Callianassa beds, and in a "bare zone" of sandflat between these two habitats that lacks both sandprawns and cordgrass. Sediments in Spartina habitats were consolidated by the root-shoot systems of the cordgrass, leading to low sediment penetrability, while sediments in beds of C. kraussi were more penetrable, primarily due to the destabilising effects of sandprawn bioturbation. Sediments in the "bare zone" had intermediate to low values of penetrability. Sediment organic content was lowest in bare zones and greatest in Spartina beds, while sediment chl- a levels were greatest on bare sand, but were progressively reduced in the Spartina and Callianassa beds. These differences among habitats induced by ecosystem engineering in turn affected the macrofauna. Community structure was different between all three habitats sampled, with species richness being surprisingly greater in Callianassa beds than either the bare zone or Spartina beds. In general, the binding of surface sediments by the root systems of Spartina favoured rigid-bodied, surface-dwelling and tube-building species, while the destabilising effect of bioturbation by C. kraussi favoured burrowing species. The contrasting effects of these ecosystem engineers suggest that they play important roles in increasing habitat heterogeneity. Importantly, the role of bioturbation by C. kraussi in enhancing macrofaunal richness was unexpected. By loosening sediments, reducing anoxia and enhancing organic content, C. kraussi may engineer these high shore habitats to ameliorate environmental stresses or increase food availability.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prahl, F.G.; Sparrow, M.A.; Eversmeyer, B.

Elemental and stable carbon isotopic compositions and biomarker concentrations were determined in sediments from the Columbia River basin and the Washington margin in order to evaluate geochemical approaches for quantifying terrestrial organic matter in marine sediments. The biomarkers include: an homologous series of long-chain n-alkanes derived from the surface waxes of higher plants; phenolic and hydroxyalkanoic compounds produced by CuO oxidation of two major vascular plant biopolymers, lignin and cutin. All marine sediments, including samples collected from the most remote sites in Cascadia Basin, showed organic geochemical evidence for the presence of terrestrial organic carbon. Using endmember values for themore » various biomarkers determined empirically by two independent means, the authors estimate that the terrestrial contribution to the Washington margin is [approximately] 60% for shelf sediments, [approximately] 30% for slope sediments, and decreases further to [le] 15% in basin sediments. Results from the same geochemical measurements made with depth in gravity core 6705-7 from Cascadia Seachannel suggest that this approach to assess terrestrial organic carbon contributions to contemporary deposits on the Washington margin can be applied to the study of sediments depositing in this region since the last glacial period.« less

Reactive-transport modeling of iron diagenesis and associated organic carbon remineralization in a Florida (USA) subterranean estuary

USGS Publications Warehouse

Roy, Moutusi; Martin, Jonathan B.; Smith, Christopher G.; Cable, Jaye E.

2011-01-01

Iron oxides are important terminal electron acceptors for organic carbon (OC) remineralization in subterranean estuaries, particularly where oxygen and nitrate concentrations are low. In Indian River Lagoon, Florida, USA, terrestrial Fe-oxides dissolve at the seaward edge of the seepage face and flow upward into overlying marine sediments where they precipitate as Fe-sulfides. The dissolved Fe concentrations vary by over three orders of magnitude, but Fe-oxide dissolution rates are similar across the 25-m wide seepage face, averaging around 0.21 mg/cm2/yr. The constant dissolution rate, but differing concentrations, indicate Fe dissolution is controlled by a combination of increasing lability of dissolved organic carbon (DOC) and slower porewater flow velocities with distance offshore. In contrast, the average rate constants of Fe-sulfide precipitation decrease from 21.9 × 10-8 s-1 to 0.64 × 10-8 s-1 from the shoreline to the seaward edge of the seepage face as more oxygenated surface water circulates through the sediment. The amount of OC remineralized by Fe-oxides varies little across the seepage face, averaging 5.34 × 10-2 mg/cm2/yr. These rates suggest about 3.4 kg of marine DOC was remineralized in a 1-m wide, shore-perpendicular strip of the seepage face as the terrestrial sediments were transgressed over the past 280 years. During this time, about 10 times more marine solid organic carbon (SOC) accumulated in marine sediments than were removed from the underlying terrestrial sediments. Indian River Lagoon thus appears to be a net sink for marine OC.

Tracing the Cycling and Fate of the Explosive 2,4,6-Trinitrotoluene in Coastal Marine Systems with a Stable Isotopic Tracer, (15)N-[TNT].

PubMed

Smith, Richard W; Vlahos, Penny; Böhlke, J K; Ariyarathna, Thivanka; Ballentine, Mark; Cooper, Christopher; Fallis, Stephen; Groshens, Thomas J; Tobias, Craig

2015-10-20

2,4,6-Trinitrotoluene (TNT) has been used as a military explosive for over a hundred years. Contamination concerns have arisen as a result of manufacturing and use on a large scale; however, despite decades of work addressing TNT contamination in the environment, its fate in marine ecosystems is not fully resolved. Here we examine the cycling and fate of TNT in the coastal marine systems by spiking a marine mesocosm containing seawater, sediments, and macrobiota with isotopically labeled TNT ((15)N-[TNT]), simultaneously monitoring removal, transformation, mineralization, sorption, and biological uptake over a period of 16 days. TNT degradation was rapid, and we observed accumulation of reduced transformation products dissolved in the water column and in pore waters, sorbed to sediments and suspended particulate matter (SPM), and in the tissues of macrobiota. Bulk δ(15)N analysis of sediments, SPM, and tissues revealed large quantities of (15)N beyond that accounted for in identifiable derivatives. TNT-derived N was also found in the dissolved inorganic N (DIN) pool. Using multivariate statistical analysis and a (15)N mass balance approach, we identify the major transformation pathways of TNT, including the deamination of reduced TNT derivatives, potentially promoted by sorption to SPM and oxic surface sediments.

Tracing the cycling and fate of the explosive 2,4,6-trinitrotoluene in coastal marine systems with a stable isotopic tracer, 15N-[TNT

USGS Publications Warehouse

Smith, Richard W.; Vlahos, Penny; Böhlke, John Karl; Ariyarathna, Thivanka; Ballentine, Mark; Cooper, Christopher; Fallis, Stephen; Groshens, Thomas J.; Tobias, Craig

2015-01-01

2,4,6-Trinitrotoluene (TNT) has been used as a military explosive for over a hundred years. Contamination concerns have arisen as a result of manufacturing and use on a large scale; however, despite decades of work addressing TNT contamination in the environment, its fate in marine ecosystems is not fully resolved. Here we examine the cycling and fate of TNT in the coastal marine systems by spiking a marine mesocosm containing seawater, sediments, and macrobiota with isotopically labeled TNT (15N-[TNT]), simultaneously monitoring removal, transformation, mineralization, sorption, and biological uptake over a period of 16 days. TNT degradation was rapid, and we observed accumulation of reduced transformation products dissolved in the water column and in pore waters, sorbed to sediments and suspended particulate matter (SPM), and in the tissues of macrobiota. Bulk δ15N analysis of sediments, SPM, and tissues revealed large quantities of 15N beyond that accounted for in identifiable derivatives. TNT-derived N was also found in the dissolved inorganic N (DIN) pool. Using multivariate statistical analysis and a 15N mass balance approach, we identify the major transformation pathways of TNT, including the deamination of reduced TNT derivatives, potentially promoted by sorption to SPM and oxic surface sediments.

Groundfish overfishing, diatom decline, and the marine silica cycle: Lessons from Saanich Inlet, Canada, and the Baltic Sea cod crash

NASA Astrophysics Data System (ADS)

Katz, Timor; Yahel, Gitai; Yahel, Ruthy; Tunnicliffe, Verena; Herut, Barak; Snelgrove, Paul; Crusius, John; Lazar, Boaz

2009-12-01

In this study, we link groundfish activity to the marine silica cycle and suggest that the drastic mid-1980s crash of the Baltic Sea cod (Gadus morhua) population triggered a cascade of events leading to decrease in dissolved silica (DSi) and diatom abundance in the water. We suggest that this seemingly unrelated sequence of events was caused by a marked decline in sediment resuspension associated with reduced groundfish activity resulting from the cod crash. In a study in Saanich Inlet, British Columbia, Canada, we discovered that, by resuspending bottom sediments, groundfish triple DSi fluxes from the sediments and reduce silica accumulation therein. Using these findings and the available oceanographic and environmental data from the Baltic Sea, we estimate that overfishing and recruitment failure of Baltic cod reduced by 20% the DSi supply from bottom sediments to the surface water leading to a decline in the diatom population in the Baltic Sea. The major importance of the marginal ocean in the marine silica cycle and the associated high population density of groundfish suggest that groundfish play a major role in the silica cycle. We postulate that dwindling groundfish populations caused by anthropogenic perturbations, e.g., overfishing and bottom water anoxia, may cause shifts in marine phytoplankton communities.

Spatial distribution, enrichment, and source of environmentally important elements in Batticaloa lagoon, Sri Lanka.

PubMed

Adikaram, Madurya; Pitawala, Amarasooriya; Ishiga, Hiroaki; Jayawardana, Daham

2017-01-01

The present paper is the first documentation of distribution and contamination status of environmentally important elements of superficial sediments in the Batticaloa lagoon that is connected to the largest bay of the world. Surface sediment samples were collected from 34 sites covering all over the lagoon. Concentrations of elements such as As, Cr, Cu, Fe, Nb, Ni, Pb, Sc, Sr, Th, V, Y, Zn, and Zr were measured by X-ray florescence analysis. Geochemically, the lagoon has three different zones that were influenced mainly by fresh water sources, marine fronts, and intermediate mixing zones. The marine sediment quality standards indicate that Zr and Th values are exceeded throughout the lagoon. According to the freshwater sediment quality standards, Cr levels of all sampling sites exceed the threshold effect level (TEL) and 17 % of them are even above the probable effect level (PEL). Most sampling sites of the channel discharging areas show minor enrichment of Cu, Ni, and Zn with respect to the TEL. Contamination indices show that the lagoon mouth area is enriched with As. Statistical analysis implies that discharges from agricultural channel and marine fluxes of the lagoon effects on the spatial distribution of measured elements. Further research is required to understand the rate of contamination in the studied marine system.

Surface sediment quality relative to port activities: A contaminant-spectrum assessment.

PubMed

Yu, Shen; Hong, Bing; Ma, Jun; Chen, Yongshan; Xi, Xiuping; Gao, Jingbo; Hu, Xiuqin; Xu, Xiangrong; Sun, Yuxin

2017-10-15

Ports are facing increasing environmental concerns with their importance to the global economy. Numerous studies indicated sediment quality deterioration in ports; however, the deterioration is not discriminated for each port activity. This study investigated a spectrum of contaminants (metals and organic pollutants) in surface sediments at 20 sampling points in Port Ningbo, China, one of the top five world ports by volume. The spectrum of contaminants (metals and organic pollutants) was quantified following marine sediment quality guidelines of China and USA and surface sediment quality was assessed according to thresholds of the two guidelines. Coupling a categorical matrix of port activities with the matrix of sedimentary contaminants revealed that contaminants were highly associated with the port operations. Ship repair posed a severe chemical risk to sediment. Operations of crude oil and coal loadings were two top activities related to organic pollutants in sediments while port operations of ore and container loadings discharged metals. Among the 20 sampling points, Cu, Zn, Pb, and DDT and its metabolites were the priority contaminants influencing sediment quality. Overall, surface sediments in Port Ningbo had relatively low environmental risks but ship repair is an environmental concern that must be addressed. This study provides a practical approach for port activity-related quality assessment of surface sediments in ports that could be applicable in many world sites. Copyright © 2017 Elsevier B.V. All rights reserved.

Neogene sequence stratigraphy, Nam Con Son Basin, offshore Vietnam

DOE Office of Scientific and Technical Information (OSTI.GOV)

McMillen, K.J.; Do Van Luu; Lee, E.K.

1996-12-31

An integrated well log, biostratigraphic, and seismic stratigraphic study of Miocene to Recent deltaic sediments deposited in the Nam Con Son Basin offshore from southern Vietnam shows the influence of eustacy and tectonics on sequence development. Sediments consist of Oligocene non-marine rift-basin fill (Cau Formation), early to middle Miocene tide-dominated delta plain to delta front sediments (TB 1.5 to TB 2.5, Due and Thong Formations), and late Miocene to Recent marine shelf sediments (TB. 2.6 to TB 3.1 0, Mang Cau, Nam Con Son, and Bien Dong Formations). Eustacy controlled the timing of key surfaces and sand distribution in themore » tectonically-quiet early Miocene. Tectonic effects on middle to late Miocene sequence development consist of thick transgressive systems tracts due to basin-wide subsidence and transgression, sand distribution in the basin center, and carbonate sedimentation on isolated fault blocks within the basin. Third-order sequence boundaries (SB) are identified by spore peaks, sand stacking patterns, and channel incision. In the basin center, widespread shale beds with coal occur above sequence boundaries followed by transgressive sandstone units. These TST sandstones merge toward the basin margin where they lie on older HST sandstones. Maximum flooding surfaces (MFS) have abundant marine microfossils and mangrove pollen, a change in sand stacking pattern, and often a strong seismic reflection with downlap. Fourth-order genetic-type sequences are also interpreted. The MFS is the easiest marker to identify and correlate on well logs. Fourth-order SB occur within these genetic units but are harder to identify and correlate.« less

Neogene sequence stratigraphy, Nam Con Son Basin, offshore Vietnam

DOE Office of Scientific and Technical Information (OSTI.GOV)

McMillen, K.J.; Do Van Luu; Lee, E.K.

1996-01-01

An integrated well log, biostratigraphic, and seismic stratigraphic study of Miocene to Recent deltaic sediments deposited in the Nam Con Son Basin offshore from southern Vietnam shows the influence of eustacy and tectonics on sequence development. Sediments consist of Oligocene non-marine rift-basin fill (Cau Formation), early to middle Miocene tide-dominated delta plain to delta front sediments (TB 1.5 to TB 2.5, Due and Thong Formations), and late Miocene to Recent marine shelf sediments (TB. 2.6 to TB 3.1 0, Mang Cau, Nam Con Son, and Bien Dong Formations). Eustacy controlled the timing of key surfaces and sand distribution in themore » tectonically-quiet early Miocene. Tectonic effects on middle to late Miocene sequence development consist of thick transgressive systems tracts due to basin-wide subsidence and transgression, sand distribution in the basin center, and carbonate sedimentation on isolated fault blocks within the basin. Third-order sequence boundaries (SB) are identified by spore peaks, sand stacking patterns, and channel incision. In the basin center, widespread shale beds with coal occur above sequence boundaries followed by transgressive sandstone units. These TST sandstones merge toward the basin margin where they lie on older HST sandstones. Maximum flooding surfaces (MFS) have abundant marine microfossils and mangrove pollen, a change in sand stacking pattern, and often a strong seismic reflection with downlap. Fourth-order genetic-type sequences are also interpreted. The MFS is the easiest marker to identify and correlate on well logs. Fourth-order SB occur within these genetic units but are harder to identify and correlate.« less

Characterization of Archaeal Community in Contaminated and Uncontaminated Surface Stream Sediments

PubMed Central

Porat, Iris; Vishnivetskaya, Tatiana A.; Mosher, Jennifer J.; Brandt, Craig C.; Yang, Zamin K.; Brooks, Scott C.; Liang, Liyuan; Drake, Meghan M.; Podar, Mircea; Brown, Steven D.

2010-01-01

Archaeal communities from mercury and uranium-contaminated freshwater stream sediments were characterized and compared to archaeal communities present in an uncontaminated stream located in the vicinity of Oak Ridge, TN, USA. The distribution of the Archaea was determined by pyrosequencing analysis of the V4 region of 16S rRNA amplified from 12 streambed surface sediments. Crenarchaeota comprised 76% of the 1,670 archaeal sequences and the remaining 24% were from Euryarchaeota. Phylogenetic analysis further classified the Crenarchaeota as a Freshwater Group, Miscellaneous Crenarchaeota group, Group I3, Rice Cluster VI and IV, Marine Group I and Marine Benthic Group B; and the Euryarchaeota into Methanomicrobiales, Methanosarcinales, Methanobacteriales, Rice Cluster III, Marine Benthic Group D, Deep Sea Hydrothermal Vent Euryarchaeota 1 and Eury 5. All groups were previously described. Both hydrogen- and acetate-dependent methanogens were found in all samples. Most of the groups (with 60% of the sequences) described in this study were not similar to any cultivated isolates, making it difficult to discern their function in the freshwater microbial community. A significant decrease in the number of sequences, as well as in the diversity of archaeal communities was found in the contaminated sites. The Marine Group I, including the ammonia oxidizer Nitrosopumilus maritimus, was the dominant group in both mercury and uranium/nitrate-contaminated sites. The uranium-contaminated site also contained a high concentration of nitrate, thus Marine Group I may play a role in nitrogen cycle. Electronic supplementary material The online version of this article (doi:10.1007/s00248-010-9734-2) contains supplementary material, which is available to authorized users. PMID:20725722

Temporal variations of 90Sr and 137Cs concentrations in Japanese coastal surface seawater and sediments from 1974 to 1998

NASA Astrophysics Data System (ADS)

Ikeuchi, Yoshihiro

2003-09-01

90Sr and 137Cs concentrations were determined in surface water and bottom sediments collected at 11 sites offshore from Japan during the period 1974-1998, to investigate their temporal variations and behaviour in the coastal marine environment. The concentrations of 90Sr and 137Cs in surface water have decreased with time since 1974. After the period of atmospheric nuclear weapons tests, the mean residence times of 90Sr and 137Cs were about 41 and 51 years, respectively. The 137Cs/ 90Sr activity ratios in coastal seawater during the atmospheric nuclear weapons tests (up until 1980) were lower than those after the tests due to the inflow of 90Sr in river water. A sharp increase in 137Cs levels was observed in airborne dust, in precipitation on the Japanese islands, and in coastal surface seawater in 1986 following the Chernobyl accident. However, the 137Cs levels in surface water returned to pre-1986 levels quickly, indicating rapid removal of Cs from the surface to deeper water. Concentrations of 90Sr in sediments were generally much lower than those for 137Cs, reflecting the more effective scavenging of Cs from the water column. In Ca-rich sediments, consisting of corals and shells, higher 90Sr levels and 90Sr/ 137Cs activity ratios were found, reflecting higher accumulation of Sr than Cs in marine organisms. Higher accumulation of 90Sr than 137Cs was also found in seaweed (gulfweed and wakame).

Role of Resuspended Sediments in the Transport and Bioaccumulation of Toxic Organic Contaminants in the Nearshore Marine Environment

DTIC Science & Technology

1994-10-11

predictions for the resuspended BRH sediments is not known but would be explained by another pool of sorption stibstrate acting to make up the difference...wo.ad lie in the presence of other active surfaces in addition to the organic carbon; it is possible that sorption onto mineral surfaces may be an...HOCs in the Great Lakes (Baker et al., 1986). Under conditions with a surplus of active sorption sites, the thermodynamic partition coefficient should

Distribution and ecological risk assessment of HCHs and DDTs in surface seawater and sediment of the mariculture area of Jincheng Bay, China

NASA Astrophysics Data System (ADS)

Hu, Yanbing; Sun, Shan; Song, Xiukai; Ma, Jianxin; Ru, Shaoguo

2015-04-01

The distribution of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in the surface seawater and sediment of Jincheng Bay mariculture area were investigated in the present study. The concentration of total HCHs and DDTs ranged from 2.98 to 14.87 ng L-1 and were < 0.032 ng L-1, respectively, in surface seawater, and ranged from 5.52 to 9.43 and from 4.11 to 6.72 ng g-1, respectively, in surface sediment. It was deduced from the composition profile of HCH isomers and DDT congeners that HCH residues derived from a mixture of technical-grade HCH and lindane whereas the DDT residues derived from technical-grade DDT and dicofol. Moreover, both HCH and DDT residues may mainly originate from historical inputs. The hazard quotient of α-HCH, β-HCH, γ-HCH and δ-HCH to marine species was 0.030, 0.157, 3.008 and 0.008, respectively. It was estimated that the overall probability of adverse biological effect from HCHs was less than 5%, indicating that its risk to seawater column species was low. The threshold effect concentration exceeding frequency of γ-HCH, p, p'-DDD, p, p'-DDE and p, p'-DDT in sediment ranged from 8.3% to 100%, and the relative concentration of the HCH and DDT mixture exceeded their probable effect level in sediment. These findings indicated that the risk to marine benthos was high and potentially detrimental to the safety of aquatic products, e.g., sea cucumber and benthic shellfish.

Vertical and horizontal distribution of radionuclides ({sup 232}Th, {sup 238}U and {sup 40}K) in sediment from Manjung coastal water area Perak, Malaysia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdullah, Anisa, E-mail: coppering@ymail.com; Hamzah, Zaini; Wood, Ab. Khalik

Distribution of radionuclides from anthropogenic activities has been widely studied in marine coastal area. Due to rapid population growth and socio-economic development in Manjung area such as coal fired power plant, iron foundries, port development, waste discharged from factories and agriculture runoff may contribute to increase in pollution rate. The radioactive materials from anthropogenic activities could deteriorate the quality of the marine ecosystem and thus lead to possible radiological health risk to the population. Radionuclides ({sup 232}Th, {sup 238}U and {sup 40}K) content in surface and profile sediment from Manjung coastal area was determined in this study. Radionuclides in sedimentmore » from seven locations were collected using sediment core sampling and measurements were carried out using Energy Dispersive X-ray Fluorescence (EDXRF) spectroscopy. The results show that the concentration of radionuclides in surface sediment and distribution trend of depth vertical profile sediment generally varies depending on locations. Enrichment factors (EF), geo-accumulation index (I{sub geo}) and pollution index (PI) were applied to determine level of pollution of this study area. The radiological risks related to human exposure were evaluated based on external hazard index (H{sub ex})« less

Distribution of tributyltin in surface sediments from transitional marine-lagoon system of the south-eastern Baltic Sea, Lithuania.

PubMed

Suzdalev, Sergej; Gulbinskas, Saulius; Blažauskas, Nerijus

2015-02-01

The current research paper presents the results of contamination by tributyltin (TBT) compounds in Klaipėda Port, which is situated in a unique marine-lagoon water interaction zone. One hundred fifty-four surface sediment samples have been taken along the whole transition path from lagoon to the sea and analysed in order to quantify the contamination rate in specific environment of high anthropogenic pressure. The detected TBT concentrations ranged from 1 to 5,200 ng Sn g(-1) of dry weight of sediment. The back-trace of horizontal distribution of TBT-contaminated sediments show obvious increase of tributyltin concentrations closer to port areas dealing with ship repair and places of dry-docking facilities. This is a clear indication that those activities are the main source of contamination in the study area. The estimated correlation of TBT concentration in sediments with total organic carbon and the amount of fine fraction (<0.063 mm) was significant for most of the stations. The TBT concentration in those sites varies from 1 to 100 ng Sn g(-1). This fact indicates that the most intensive accumulation of tributyltin is related to potential contamination source areas (ship repairing, dockyards) due to direct input of hazardous substances into the water.

Using network to enhance the insights on correlation and pollution assessment of co-occurring metals in marine sediments, the East China Sea.

PubMed

Liu, Lili; Wang, Yupeng; Lin, Sen; Li, Hong; Chen, Xin; Wang, Zhiping; Lin, Kuangfei

2018-04-01

In this study, sediment samples were collected from 24 sites in the East China Sea (ECS) to investigate the distribution characteristics, co-occurrence correlations, and ecological risks of metals. In surface sediments, metals presented a homologous banding distribution pattern decreasing seaward with distance. With network analysis, it indicated metals in this area might directly derive from the coastal river inputs. According to geo-accumulation indexes (I geo ), Cd was classified as moderate pollution at 58% sites, far above other metals. In addition, the potential ecological risk index (RI) was clustered with the ecological risk (ER) of Cd, which was regarded as considerable or high-risk level for most coastal stations. Thus Cd pollution in the ESC sediment should be paid more attention. In sum, the visualization of statistical analyses combined with geochemical approaches could reveal the potential sources of contaminants and ecological risks, thus facilitate the pollution evaluation in marine sediments.

Immediate propagation of deglacial environmental change to deep-marine turbidite systems along the Chile convergent margin

NASA Astrophysics Data System (ADS)

Bernhardt, Anne; Schwanghart, Wolfgang; Hebbeln, Dierk; Stuut, Jan-Berend W.; Strecker, Manfred R.

2017-09-01

Understanding how Earth-surface processes respond to past climatic perturbations is crucial for making informed predictions about future impacts of climate change on sediment fluxes. Sedimentary records provide the archives for inferring these processes, but their interpretation is compromised by our incomplete understanding of how sediment-routing systems respond to millennial-scale climate cycles. We analyzed seven sediment cores recovered from marine turbidite depositional sites along the Chile continental margin. The sites span a pronounced arid-to-humid gradient with variable relief and related sediment connectivity of terrestrial and marine environments. These sites allowed us to study event-related depositional processes in different climatic and geomorphic settings from the Last Glacial Maximum to the present day. The three sites reveal a steep decline of turbidite deposition during deglaciation. High rates of sea-level rise postdate the decline in turbidite deposition. Comparison with paleoclimate proxies documents that the spatio-temporal sedimentary pattern rather mirrors the deglacial humidity decrease and concomitant warming with no resolvable lag times. Our results let us infer that declining deglacial humidity decreased fluvial sediment supply. This signal propagated rapidly through the highly connected systems into the marine sink in north-central Chile. In contrast, in south-central Chile, connectivity between the Andean erosional zone and the fluvial transfer zone probably decreased abruptly by sediment trapping in piedmont lakes related to deglaciation, resulting in a sudden decrease of sediment supply to the ocean. Additionally, reduced moisture supply may have contributed to the rapid decline of turbidite deposition. These different causes result in similar depositional patterns in the marine sinks. We conclude that turbiditic strata may constitute reliable recorders of climate change across a wide range of climatic zones and geomorphic conditions. However, the underlying causes for similar signal manifestations in the sinks may differ, ranging from maintained high system connectivity to abrupt connectivity loss.

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

PubMed

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 CO 2 ) 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 CO 2 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.

Nitrogen Losses in Sediments of the East China Sea: Spatiotemporal Variations, Controlling Factors, and Environmental Implications

NASA Astrophysics Data System (ADS)

Lin, Xianbiao; Liu, Min; Hou, Lijun; Gao, Dengzhou; Li, Xiaofei; Lu, Kaijun; Gao, Juan

2017-10-01

Global reactive nitrogen (N) has increased dramatically in coastal marine ecosystems over the past decades and caused numerous eco-environmental problems. Coastal marine sediment plays a critical role in N losses via denitrification and anaerobic ammonium oxidation (anammox) and release of nitrous oxide (N2O). However, both the magnitude and contributions of denitrification, anammox, and N2O production in sediments still remain unclear, causing uncertainty in defining the N budget for coastal marine ecosystems. Here potential rates of N losses, and their contributions and controlling factors, were investigated in surface sediments during six cruises from 429 sites of the East China Sea. The potential rates of denitrification, anammox, and N2O production varied both spatially and seasonally, but the contribution of anammmox to total N2 production (%anammox) and N2O:N2 ratio only varied spatially. Both organic carbon and nitrate (NO3-) were important factors controlling N losses, N2O:N2 ratio, and %anammox. Our results also showed that marine organic carbon induced by eutrophication plays an important role in stimulating reactive N removal and increasing N2O production in warm seasons. The sediment N loss caused by denitrification, anammox, and N2O production in the study area were estimated at 2.2 × 106 t N yr-1, 4.6 × 105 t N yr-1, and 8 × 103 t N yr-1, respectively. Although sediments remove large quantities of reactive N, they act as an important source of N2O in this region influenced by NO3--laden rivers.

Natural occurrence of microbial sulphur oxidation by long-range electron transport in the seafloor

PubMed Central

Malkin, Sairah Y; Rao, Alexandra MF; Seitaj, Dorina; Vasquez-Cardenas, Diana; Zetsche, Eva-Maria; Hidalgo-Martinez, Silvia; Boschker, Henricus TS; Meysman, Filip JR

2014-01-01

Recently, a novel mode of sulphur oxidation was described in marine sediments, in which sulphide oxidation in deeper anoxic layers was electrically coupled to oxygen reduction at the sediment surface. Subsequent experimental evidence identified that long filamentous bacteria belonging to the family Desulfobulbaceae likely mediated the electron transport across the centimetre-scale distances. Such long-range electron transfer challenges some long-held views in microbial ecology and could have profound implications for sulphur cycling in marine sediments. But, so far, this process of electrogenic sulphur oxidation has been documented only in laboratory experiments and so its imprint on the seafloor remains unknown. Here we show that the geochemical signature of electrogenic sulphur oxidation occurs in a variety of coastal sediment environments, including a salt marsh, a seasonally hypoxic basin, and a subtidal coastal mud plain. In all cases, electrogenic sulphur oxidation was detected together with an abundance of Desulfobulbaceae filaments. Complementary laboratory experiments in intertidal sands demonstrated that mechanical disturbance by bioturbating fauna destroys the electrogenic sulphur oxidation signal. A survey of published geochemical data and 16S rRNA gene sequences identified that electrogenic sulphide oxidation is likely present in a variety of marine sediments with high sulphide generation and restricted bioturbation, such as mangrove swamps, aquaculture areas, seasonally hypoxic basins, cold sulphide seeps and possibly hydrothermal vent environments. This study shows for the first time that electrogenic sulphur oxidation occurs in a wide range of marine sediments and that bioturbation may exert a dominant control on its natural distribution. PMID:24671086

Natural occurrence of microbial sulphur oxidation by long-range electron transport in the seafloor.

PubMed

Malkin, Sairah Y; Rao, Alexandra M F; Seitaj, Dorina; Vasquez-Cardenas, Diana; Zetsche, Eva-Maria; Hidalgo-Martinez, Silvia; Boschker, Henricus T S; Meysman, Filip J R

2014-09-01

Recently, a novel mode of sulphur oxidation was described in marine sediments, in which sulphide oxidation in deeper anoxic layers was electrically coupled to oxygen reduction at the sediment surface. Subsequent experimental evidence identified that long filamentous bacteria belonging to the family Desulfobulbaceae likely mediated the electron transport across the centimetre-scale distances. Such long-range electron transfer challenges some long-held views in microbial ecology and could have profound implications for sulphur cycling in marine sediments. But, so far, this process of electrogenic sulphur oxidation has been documented only in laboratory experiments and so its imprint on the seafloor remains unknown. Here we show that the geochemical signature of electrogenic sulphur oxidation occurs in a variety of coastal sediment environments, including a salt marsh, a seasonally hypoxic basin, and a subtidal coastal mud plain. In all cases, electrogenic sulphur oxidation was detected together with an abundance of Desulfobulbaceae filaments. Complementary laboratory experiments in intertidal sands demonstrated that mechanical disturbance by bioturbating fauna destroys the electrogenic sulphur oxidation signal. A survey of published geochemical data and 16S rRNA gene sequences identified that electrogenic sulphide oxidation is likely present in a variety of marine sediments with high sulphide generation and restricted bioturbation, such as mangrove swamps, aquaculture areas, seasonally hypoxic basins, cold sulphide seeps and possibly hydrothermal vent environments. This study shows for the first time that electrogenic sulphur oxidation occurs in a wide range of marine sediments and that bioturbation may exert a dominant control on its natural distribution.

Sources and reactivities of marine-derived organic matter in coastal sediments as determined by alkaline CuO oxidation

NASA Astrophysics Data System (ADS)

Goñi, Miguel A.; Hedges, John I.

1995-07-01

Alkaline CuO oxidation of ubiquitous biochemicals such as proteins, polysaccharides, and lipids, yields specific products, including fatty acids, diacids, and carboxylated phenols. Oxidation of a variety of marine organisms, including macrophytes, phytoplankton, zooplankton, and bacteria, yields these CuO products in characteristic patterns that can often differentiate these biological sources. Sediments from Skan Bay (Unalaska Island, Alaska) display organic carbon and total nitrogen profiles which are consistent with three kinetically distinct pools of organic matter. The CuO fingerprints of these sediments distinguish these three pools at the molecular level, indicating a highly labile, fatty acid-rich surface organic layer of likely bacterial origin, intermediately reactive kelp debris and a background of phytoplankton remains that predominates at depth. The CuO method, which has been previously applied only to characterize cutin and lignin constituents of vascular land plants, also provides information on other types of abundant biochemicals, including those indicative of marine sources.

Surface expression of Eastern Mediterranean slab dynamics: Uplift at the SW margin of the Central Anatolian Plateau

NASA Astrophysics Data System (ADS)

Schildgen, T. F.; Cosentino, D.; Caruso, A.; Yildirim, C.; Echtler, H.; Strecker, M. R.

2011-12-01

The Central Anatolian plateau in Turkey borders one of the most complex tectonic regions on Earth, where collision of the Arabian plate with Eurasia in Eastern Anatolia transitions to a cryptic pattern of subduction of the African beneath the Eurasian plate, with concurrent westward extrusion of the Anatolian microplate. Topographic growth of the southern margin of the Central Anatolian plateau has proceeded in discrete stages that can be distinguished based on the outcrop pattern and ages of uplifted marine sediments. These marine units, together with older basement rocks and younger continental sedimentary fills, also record an evolving nature of crustal deformation and uplift patterns that can be used to test the viability of different uplift mechanisms that have contributed to generate the world's third-largest orogenic plateau. Late Miocene marine sediments outcrop along the SW plateau margin at 1.5 km elevation, while they blanket the S and SE margins at up to more than 2 km elevation. Our new biostratigraphic data limit the age of 1.5-km-high marine sediments along the SW plateau margin to < 7.17 Ma, while regional lithostratigraphic correlations imply that the age is < 6.7 Ma. After reconstructing the post-Late Miocene surface uplift pattern from elevations of uplifted marine sediments and geomorphic reference surfaces, it is clear that regional surface uplift reaches maximum values along the modern plateau margin, with the SW margin experiencing less cumulative uplift compared to the S and SE margins. Our structural measurements and inversion modeling of faults within the uplifted region agree with previous findings in surrounding regions, with early contraction followed by strike-slip and extensional deformation. Shallow earthquake focal mechanisms show that the extensional phase has continued to the present. Broad similarities in the onset of surface uplift (after 7 Ma) and a change in the kinematic evolution of the plateau margin (after 8 Ma) suggest that these phenomena may have been linked with a change in the tectonic stress field associated with the process(es) causing post-7 Ma surface uplift. The complex geometry of lithospheric slabs beneath the southern plateau margin, early Pliocene to recent alkaline volcanism, and the localized uplift pattern with accompanying tensional/transtensional stresses point toward slab tearing and localized heating at the base of the lithosphere as a probable mechanism for post-7 Ma uplift of the SW margin. Considering previous work in the region, slab break-off is more likely responsible for non-contractional uplift along the S and SE margins. Overall there appears to be an important link between slab dynamics and surface uplift across the whole southern margin of the Central Anatolian plateau.

Clay mineral continental amplifier for marine carbon sequestration in a greenhouse ocean.

PubMed

Kennedy, Martin J; Wagner, Thomas

2011-06-14

The majority of carbon sequestration at the Earth's surface occurs in marine continental margin settings within fine-grained sediments whose mineral properties are a function of continental climatic conditions. We report very high mineral surface area (MSA) values of 300 and 570 m(2) g in Late Cretaceous black shales from Ocean Drilling Program site 959 of the Deep Ivorian Basin that vary on subcentennial time scales corresponding with abrupt increases from approximately 3 to approximately 18% total organic carbon (TOC). The observed MSA changes with TOC across multiple scales of variability and on a sample-by-sample basis (centimeter scale), provides a rigorous test of a hypothesized influence on organic carbon burial by detrital clay mineral controlled MSA. Changes in TOC also correspond with geochemical and sedimentological evidence for water column anoxia. Bioturbated intervals show a lower organic carbon loading on mineral surface area of 0.1 mg-OC m(-2) when compared to 0.4 mg-OC m(-2) for laminated and sulfidic sediments. Although either anoxia or mineral surface protection may be capable of producing TOC of < 5%, when brought together they produced the very high TOC (10-18%) apparent in these sediments. This nonlinear response in carbon burial resulted from minor precession-driven changes of continental climate influencing clay mineral properties and runoff from the African continent. This study identifies a previously unrecognized land-sea connection among continental weathering, clay mineral production, and anoxia and a nonlinear effect on marine carbon sequestration during the Coniacian-Santonian Oceanic Anoxic Event 3 in the tropical eastern Atlantic.

Bulk organic δ 13C and C/N as indicators for sediment sources in the Pearl River delta and estuary, southern China

NASA Astrophysics Data System (ADS)

Yu, Fengling; Zong, Yongqiang; Lloyd, Jeremy M.; Huang, Guangqing; Leng, Melanie J.; Kendrick, Christopher; Lamb, Angela L.; Yim, Wyss W.-S.

2010-05-01

Preservation of organic matter in estuarine and coastal areas is an important process in the global carbon cycle. This paper presents bulk δ 13C and C/N of organic matter from source to sink in the Pearl River catchment, delta and estuary, and discusses the applicability of δ 13C and C/N as indicators for sources of organic matter in deltaic and estuarine sediments. In addition to the 91 surface sediment samples, other materials collected in this study cover the main sources of organic material to estuarine sediment. These are: terrestrial organic matter (TOM), including plants and soil samples from the catchment; estuarine and marine suspended particulate organic carbon (POC) from both summer and winter. Results show that the average δ 13C of estuarine surface sediment increases from -25.0 ± 1.3‰ in the freshwater environment to -21.0 ± 0.2‰ in the marine environment, with C/N decreasing from 15.2 ± 3.3 to 6.8 ± 0.2. In the source areas, C 3 plants have lower δ 13C than C 4 plants (-29.0 ± 1.8‰ and -13.1 ± 0.5‰ respectively). δ 13C increases from -28.3 ± 0.8‰ in the forest soil to around -24.1‰ in both riverbank soil and mangrove soil due to increasing proportion of C 4 grasses. The δ 13C POC increases from -27.6 ± 0.8‰ in the freshwater areas to -22.4 ± 0.5‰ in the marine-brackish-water areas in winter, and ranges between -24.0‰ in freshwater areas and -25.4‰ in brackish-water areas in summer. Comparison of the δ 13C and C/N between the sources and sink indicates a weakening TOM and freshwater POC input in the surface sedimentary organic matter seawards, and a strengthening contribution from the marine organic matter. Thus we suggest that bulk organic δ 13C and C/N analysis can be used to indicate sources of sedimentary organic matter in estuarine environments. Organic carbon in surface sediments derived from anthropogenic sources such as human waste and organic pollutants from industrial and agricultural activities accounts for less than 10% of the total organic carbon (TOC). Although results also indicate elevated δ 13C of sedimentary organic matter due to some agricultural products such as sugarcane, C 3 plants are still the dominant vegetation type in this area, and the bulk organic δ 13C and C/N is still an effective indicator for sources of organic matter in estuarine sediments.

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

PubMed Central

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

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

PubMed

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

2012-11-01

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

Terrestrial organic carbon contributions to sediments on the Washington margin

NASA Astrophysics Data System (ADS)

Prahl, F. G.; Ertel, J. R.; Goni, M. A.; Sparrow, M. A.; Eversmeyer, B.

1994-07-01

Elemental and stable carbon isotopic compositions and biomarker concentrations were determined in sediments from the Columbia River basin and the Washington margin in order to evaluate geochemical approaches for quantifying terrestrial organic matter in marine sediments. The biomarkers include: an homologous series of long-chain n-alkanes derived from the surface waxes of higher plants; phenolic and hydroxyalkanoic compounds produced by CuO oxidation of two major vascular plant biopolymers, lignin and cutin. All marine sediments, including samples collected from the most remote sites in Cascadia Basin, showed organic geochemical evidence for the presence of terrestrial organic carbon. Using endmember values for the various biomarkers determined empirically by two independent means, we estimate that the terrestrial contribution to the Washington margin is ~ 60% for shelf sediments, ~ 30% for slope sediments, and decreases further to ≤15% in basin sediments. Results from the same geochemical measurements made with depth in gravity core 6705-7 from Cascadia Seachannel suggest that our approach to assess terrestrial organic carbon contributions to contemporary deposits on the Washington margin can be applied to the study of sediments depositing in this region since the last glacial period.

Multi-heme cytochromes provide a pathway for survival in energy-limited environments

PubMed Central

Deng, Xiao; Dohmae, Naoshi; Nealson, Kenneth H.; Hashimoto, Kazuhito; Okamoto, Akihiro

2018-01-01

Bacterial reduction of oxidized sulfur species (OSS) is critical for energy production in anaerobic marine subsurfaces. In organic-poor sediments, H2 has been considered as a major energy source for bacterial respiration. We identified outer-membrane cytochromes (OMCs) that are broadly conserved in sediment OSS-respiring bacteria and enable cells to directly use electrons from insoluble minerals via extracellular electron transport. Biochemical, transcriptomic, and microscopic analyses revealed that the identified OMCs were highly expressed on the surface of cells and nanofilaments in response to electron donor limitation. This electron uptake mechanism provides sufficient but minimum energy to drive the reduction of sulfate and other OSS. These results suggest a widespread mechanism for survival of OSS-respiring bacteria via electron uptake from solid minerals in energy-poor marine sediments. PMID:29464208

Reappraisal of the sequence boundary in time and space: Case and considerations for an SU (subaerial unconformity) that is not a sediment bypass surface, a time barrier, or an unconformity

NASA Astrophysics Data System (ADS)

Holbrook, John M.; Bhattacharya, Janok P.

2012-07-01

The sequence-bounding unconformity bears the key defining traits of being "a surface separating younger from older strata, along which there is evidence of subaerial erosional truncation … or subaerial exposure, with a significant hiatus indicated (Van Wagoner et al., 1988)." This subaerial component of sequence boundaries (subaerial unconformity—SU) is also broadly considered to form as a topographic surface of sediment bypass, carved during relative sea level fall and buried by backfilling during relative sea level rise. Accordingly, the SU is commonly presumed to record an approximate time barrier, which separates older from younger strata along its full length. In this paper we show that regional composite scour (RCS) surfaces that are traditionally mapped as an integral component of the SU were never a single subaerial topographic surface characterized by sediment bypass, are not unconformities, do not record an effective time barrier, and form diachronously at the channel-belt scale over the entire fall to rise of a base-level cycle. These RCS surfaces, and by inference the SU surfaces they comprise, thus do not fully fit key defining characteristics embodied in the conceptual sequence boundary. Flume observations and field data show that the RCS is buried by fluvial sediment simultaneously as it is scoured. Accordingly, the RCS is perennially covered with stored sediment during formation, is only exposed as a subaerial topographic surface at the local place and time where it is undergoing active growth, and forms over the duration of local marine drainage during a relative sea-level cycle. This "cut-and-cover" model differs greatly from more established "bypass" models, which assume that the RCS was roughly sediment free and subaerially exposed for long durations of incision during regression and thus preserves a significant depositional hiatus upon later burial. Instead, the RCS may commonly and locally record a hiatus more typical of a facies-bounding diastem without a lacuna significantly greater than that of surfaces within the strata it binds. Fragments of fluvial strata may commonly and sporadically be preserved above the RCS that are older than underlying marine units overrun by this surface. Consequently, the RCS is not an effective time barrier. Lateral planation by migrating and avulsing channels as the RCS expands laterally after nucleation can place younger fluvial strata over much older units, which means that this surface is also composite and highly diachronous laterally at the scale of channel belts. The cut-and-cover model has additional implications not captured by the bypass model. First, significant sediments may be stored within fluvial strata above the RCS during regression that are not available for contemporary falling stage and lowstand marine shorelines. This can result in marine sediment starvation, particularly of the sand fraction, and in extreme cases can result in sand autodetachment and an absence of regressive marine reservoir sandstones. Second, cutting of the RCS co-generates a suprafluvial surface above the covering fluvial strata during regression that may be used as a mappable proxy for the conceptual maximum regressive surface (MRS). The MRS may be raised above this surface locally by low-accommodation aggradation during lowstand normal regression, but in either case preserves an approximate time line where not reworked during later transgression. Third, valley development across the RCS does not exclusively form by landward knickpoint growth, and may include complexly formed and potentially cross-cutting buffer valleys. SU valley incision can be divided into four modes, which include denudation, structural, buttress, and buffer valley components, which may work together locally and tend to have variable importance along the shore-to-hinterland profile. Although the RCS is not a good rock proxy for the conceptual sequence boundary it remains a very mappable surface which may separate facies of potentially very different origin and reservoir quality. The RCS is also inseparable from the SU and typically the only terrestrial erosional surface of extent in most short-duration sequences. Its nullification as a sequence boundary would mean abandonment of depositional sequence stratigraphy as a correlation and interpretive tool within these sections. An alternative to abandonment of the SU as a sequence boundary is to loosen the definition of a sequence boundary to 'a discrete surface of erosional truncation carved landward of contemporary shorelines that is traceable beyond the scale of a single valley or comparable local system, and its correlative surfaces of conformity and/or non-deposition', and continue its use as before.

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

PubMed

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

2016-01-01

Examination of the partitioning of explosives onto sediment in marine environments is critical to predict the toxicological impacts of worldwide explosive-contaminated sites adjacent to estuaries, wetlands, and the coastal ocean. Marine sediments have been identified as sites of enhanced munitions removal, yet most studies addressing these interactions focus on soils and freshwater sediments. The present study measured the kinetics of 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) sorption onto 2 marine sediments of varying grain sizes (silt vs sand) and organic carbon (OC) content. Abiotic sediment sorption tests were performed at 23 °C, 15 °C, and 4 °C by spiking TNT and RDX solutions directly into anaerobic sediment slurries. Marine sediments showed significantly higher compound uptake rates (0.30-0.80 h(-1) ) than freshwater silt (0.0046-0.0065 h(-1) ) for both compounds, probably because of lower compound solubilities and a higher pH in marine systems. Equilibrium partition constants are on the same order of magnitude for marine silt (1.1-2.0 L kg(-1) sediment) and freshwater silt (1.4-3.1 L kg(-1) sediment) but lower for marine sand (0.72-0.92 L kg(-1) sediment). Total organic carbon content in marine sediments varied linearly with equilibrium partition constants for TNT and was moderately linear for RDX. Uptake rates and equilibrium constants of explosives are inversely correlated to temperature regardless of sediment type because of kinetic barriers associated with low temperatures. © 2015 SETAC.

Seabed maps showing topography, ruggedness, backscatter intensity, sediment mobility, and the distribution of geologic substrates in Quadrangle 6 of the Stellwagen Bank National Marine Sanctuary Region offshore of Boston, Massachusetts

USGS Publications Warehouse

Valentine, Page C.; Gallea, Leslie B.

2015-11-10

The U.S. Geological Survey (USGS), in cooperation with the National Oceanic and Atmospheric Administration's National Marine Sanctuary Program, has conducted seabed mapping and related research in the Stellwagen Bank National Marine Sanctuary (SBNMS) region since 1993. The area is approximately 3,700 square kilometers (km2) and is subdivided into 18 quadrangles. Seven maps, at a scale of 1:25,000, of quadrangle 6 (211 km2) depict seabed topography, backscatter, ruggedness, geology, substrate mobility, mud content, and areas dominated by fine-grained or coarse-grained sand. Interpretations of bathymetric and seabed backscatter imagery, photographs, video, and grain-size analyses were used to create the geology-based maps. In all, data from 420 stations were analyzed, including sediment samples from 325 locations. The seabed geology map shows the distribution of 10 substrate types ranging from boulder ridges to immobile, muddy sand to mobile, rippled sand. Mapped substrate types are defined on the basis of sediment grain-size composition, surface morphology, sediment layering, the mobility or immobility of substrate surfaces, and water depth range. This map series is intended to portray the major geological elements (substrates, topographic features, processes) of environments within quadrangle 6. Additionally, these maps will be the basis for the study of the ecological requirements of invertebrate and vertebrate species that utilize these substrates and guide seabed management in the region.

Fluvial landscapes evolution in the Gangkou River basin of southern Taiwan: Evidence from the sediment cores

NASA Astrophysics Data System (ADS)

Chen, Jia-Hong; Chyi, Shyh-Jeng; Yen, Jiun-Yee; Lin, Li-Hung; Yen, I.-Chin; Yu, Neng-Ti; Ho, Lih-Der; Jen, Chia-Hung

2017-04-01

The Gangkou River basin is the largest basin in the eastern Hengchun Peninsula of Taiwan. Its main river length is 31km and the basin area is 102sq. km. The width of the active channel is relatively narrow, but the valley from the middle to downstream is remarkably wide, indicating a feature of underfit stream. We drilled two sediment cores in the downstream area, including a 30m core (core-A) from a higher terrace, which is 14m above mean sea level, and a 20m core (core-B) from a lower terrace, which is 4m above mean sea level. Most of the sediments in the core-A are mud, which represents the flood plain facies, and 14C dates in the core-A range from 11ka to 7ka BP. Furthermore, the sediment layers reveal signals of marine events at the core depths of 5m to 11m by X-ray fluorescence. In the core-B, there is an erosional surface at the core depth of 5m. The age of the fluvial gravel layer above the erosional surface is about 0.4ka BP, and the mud layer top the surface is about 8.5ka BP. The preliminary results show that (1) as the tectonic uplift rate induced by the marine terraces around the basin is 1.0 to 2.5 mm/yr, and the accumulation rate of the mud layer in the basin is 6.7 to 8.7 mm/yr, the sediments infilling (more than 30-meters-thick) in the downstream area of the basin should be the results of the lower tectonic uplifting and the higher post-glacial sea level rise and; (2) the marine sediment layer with 14C dates of 7.5ka to 8.5ka BP is very likely the remain of the maximum flooding surface (MFS) in the early Holocene. These results indicate that the fluvial landscapes evolution of the basin was controlled by the sea-level; (3) the erosional surface in the core-B indicates the Gangkou River continuously erode the infilling sediments from 7ka to 0.4ka BP. Previous studies show that the sea-level around Taiwan gradually declined from its high stand since 6ka, we proposed that the continuous erosion was probably the results of tectonic uplifting and eustatic sea-level fall.

Humic acids contribution to sedimentary organic matter on a shallow continental shelf (northern Adriatic Sea)

NASA Astrophysics Data System (ADS)

Giani, M.; Rampazzo, F.; Berto, D.

2010-12-01

The shallow northern Adriatic Sea receives large river runoff, predominantly from the Po River, which is the main allochthonous source of nutrients and organic matter. The origin and quality of organic matter deposited in the sediments can influence the degradation processes and oxygen consumption in the bottom waters as well as the fate of many pollutants. Therefore the humic acids (HA) were quantified in surface and sub-surface sediments collected in an area of the north-western Adriatic platform south of Po River. HA showed to have a relevant contribution to sedimentary organic matter. HA content in sediments were positively correlated with the organic carbon concentration and negatively with redox potential and pH, particularly in sub-surface reduced sediments, suggesting their important role in the diagenetic processes taking place in anoxic conditions. Elemental composition of HA extracted from surface and sub-surface sediments showed a wide range of variation of the C org/N ratios which could be due to a mixed (terrestrial and marine) origin and/or an elevated bacteria degradation of nitrogen during diagenesis processes in sediments. The spectroscopic ratios A 2/A 4 and A 4/A 6 of HA confirmed a mixed origin with a high degree of condensation of the HA extracted from sediments.

Paradise Threatened: Land Use and Erosion on St. John, US Virgin Islands

PubMed

Macdonald; Anderson; Dietrich

1997-11-01

/ Rapid development and the concomitant increases in erosion and sedimentation are believed to threaten the reefs and other marine resources that are a primary attraction of St. John and Virgin Islands National Park. Average annual sediment yields from undeveloped areas were estimated from a sediment pond and a mangrove swamp as less than 20 and less than 40 t/km2/yr, respectively. Geomorphic evidence indicates that plantation agriculture during the 18th and 19th centuries did not cause severe erosion. Since about 1950 there has been rapid growth in roads and development due to increasing tourism and second-home development. Our field investigations identified the approximately 50 km of unpaved roads as the primary source of anthropogenic sediment. Field measurements of the road network in two catchments led to the development of a vector-based GIS model to predict road surface erosion and sediment delivery. We estimate that road erosion has caused at least a fourfold increase in island-wide sediment yields and that current sedimentation rates are unprecedented. Paving the dirt roads and implementing standard sediment control practices can greatly reduce current sediment yields and possible adverse effects on the marine ecosystems surrounding St. John.KEY WORDS: Erosion; Sediment yield; Roads; Dry tropics; Development

Sedimentation pulse in the NE Gulf of Mexico following the 2010 DWH blowout

DOE PAGES

Brooks, Gregg R.; Larson, Rebekka A.; Schwing, Patrick T.; ...

2015-07-14

The objective of this study was to investigate the impacts of the Deepwater Horizon (DWH) oil discharge at the seafloor as recorded in bottom sediments of the DeSoto Canyon region in the northeastern Gulf of Mexico. Through a close coupling of sedimentological, geochemical, and biological approaches, multiple independent lines of evidence from 11 sites sampled in November/December 2010 revealed that the upper ~1 cm depth interval is distinct from underlying sediments and results indicate that particles originated at the sea surface. Consistent dissimilarities in grain size over the surficial ~1 cm of sediments correspond to excess 234Th depths, which indicatesmore » a lack of vertical mixing (bioturbation), suggesting the entire layer was deposited within a 4–5 month period. In addition, a time series from four deep-sea sites sampled up to three additional times over the following two years revealed that excess 234Th depths, accumulation rates, and 234Th inventories decreased rapidly, within a few to several months after initial coring. The interpretation of a rapid sedimentation pulse is corroborated by stratification in solid phase Mn, which is linked to diagenesis and redox change, and the dramatic decrease in benthic formanifera density that was recorded in surficial sediments. Results are consistent with a brief depositional pulse that was also reported in previous studies of sediments, and marine snow formation in surface waters closer to the wellhead during the summer and fall of 2010. Although sediment input from the Mississippi River and advective transport may influence sedimentation on the seafloor in the DeSoto Canyon region, we conclude based on multidisciplinary evidence that the sedimentation pulse in late 2010 is the product of marine snow formation and is likely linked to the DWH discharge.« less

Sedimentation Pulse in the NE Gulf of Mexico following the 2010 DWH Blowout

PubMed Central

Brooks, Gregg R.; Larson, Rebekka A.; Schwing, Patrick T.; Romero, Isabel; Moore, Christopher; Reichart, Gert-Jan; Jilbert, Tom; Chanton, Jeff P.; Hastings, David W.; Overholt, Will A.; Marks, Kala P.; Kostka, Joel E.; Holmes, Charles W.; Hollander, David

2015-01-01

The objective of this study was to investigate the impacts of the Deepwater Horizon (DWH) oil discharge at the seafloor as recorded in bottom sediments of the DeSoto Canyon region in the northeastern Gulf of Mexico. Through a close coupling of sedimentological, geochemical, and biological approaches, multiple independent lines of evidence from 11 sites sampled in November/December 2010 revealed that the upper ~1 cm depth interval is distinct from underlying sediments and results indicate that particles originated at the sea surface. Consistent dissimilarities in grain size over the surficial ~1 cm of sediments correspond to excess 234Th depths, which indicates a lack of vertical mixing (bioturbation), suggesting the entire layer was deposited within a 4–5 month period. Further, a time series from four deep-sea sites sampled up to three additional times over the following two years revealed that excess 234Th depths, accumulation rates, and 234Th inventories decreased rapidly, within a few to several months after initial coring. The interpretation of a rapid sedimentation pulse is corroborated by stratification in solid phase Mn, which is linked to diagenesis and redox change, and the dramatic decrease in benthic formanifera density that was recorded in surficial sediments. Results are consistent with a brief depositional pulse that was also reported in previous studies of sediments, and marine snow formation in surface waters closer to the wellhead during the summer and fall of 2010. Although sediment input from the Mississippi River and advective transport may influence sedimentation on the seafloor in the DeSoto Canyon region, we conclude based on multidisciplinary evidence that the sedimentation pulse in late 2010 is the product of marine snow formation and is likely linked to the DWH discharge. PMID:26172639

Sulfur diagenesis in marine sediments

NASA Technical Reports Server (NTRS)

Goldhaber, M.

1985-01-01

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

Speciation and isotopic composition of sulfur in sediments from Jellyfish Lake, Palau

USGS Publications Warehouse

Bates, A.L.; Spiker, E. C.; Orem, W.H.; Burnett, W.C.

1993-01-01

Jellyfish Lake, Palau, is a meromictic marine lake with high organic productivity, low reactive Fe content, and anoxic bottom waters. Sediment samples from Jellyfish Lake were examined for the distribution of sulfur species and their isotopic signatures in order to gain a better understanding of sedimentary sulfur incorporation in Fe-poor environments. Surface samples were taken along a transect from a near-shore site to the center of the lake, and include a sample below oxic water, a sample below the chemocline layer, and samples below anoxic waters. Three additional samples were taken from a core, 2 m long, collected near the lake center. Sulfur to organic carbon weight ratios in all samples were lower than the expected value of 0.36 for normal marine sediment, probably because the lake water is deficient in reactive Fe to form iron sulfides. Total sulfur contents in the surface sediments indicated no changes with distance from shore; however, the sulfur content of the surface sample at the chemocline layer may be slightly higher. Total sulfur content increased with depth in the core and is inversely related to organic carbon content. Organic sulfur is the major sulfur species in the samples, followed in descending order by sulfate, disulfides and monosulfides. Sulfate sulfur isotope ??34S-values are positive (from +20.56 to +12.04???), reflecting the marine source of sulfate in Jellyfish Lake. Disulfide and monosulfide ??34S-values are negative (from -25.07 to -7.60???), because of fractionation during bacterial reduction of sulfate. Monosulfide ??34S-values are somewhat higher than those of disulfides, and they are close to the ??34S-values of organic sulfur. These results indicate that most of the organic sulfur is formed by reaction of bacteriogenic monosulfides, or possibly monosulfide-derived polysulfides, with organic matter in the sediment. ?? 1993.

Distribution of heavy metals in marine bivalves, fish and coastal sediments in the Gulf and Gulf of Oman.

PubMed

de Mora, Stephen; Fowler, Scott W; Wyse, Eric; Azemard, Sabine

2004-09-01

An assessment of marine contamination due to heavy metals was made in the Gulf and Gulf of Oman based on marine biota (fish and various bivalves) and coastal sediment collected in Bahrain, Oman, Qatar, and the United Arab Emirates (UAE) during 2000-2001. Sediment metal loadings were generally not remarkable, although hot spots were noted in Bahrain (Cu, Hg, Pb, Zn) and on the east coast of the UAE (As, Co, Cr, Ni). Concentrations of As and Hg were typically low in sediments and the total Hg levels in top predator fish commonly consumed in the region were < 0.5 microg g(-1) and posed no threat to public health. Very high Cd concentrations (up to 195 microg g(-1)) in the liver of some fish from southern Oman may result from food-chain bioaccumulation of elevated Cd levels brought into the productive surface waters by upwelling in the region. Very high As concentrations (up to 156 microg g(-1)) were measured in certain bivalve species from the region. Although not certain, the As is probably derived from natural origins rather than anthropogenic contamination. Copyright 2004 Elsevier Ltd.

Distribution and sources of aliphatic hydrocarbons and fatty acids in surface sediments of a tropical estuary south west coast of India (Cochin estuary).

PubMed

Gireeshkumar, T R; Deepulal, P M; Chandramohanakumar, N

2015-03-01

Surface sediments samples from the Cochin estuary were measured for elemental, stable isotopic and molecular biomarkers (aliphatic hydrocarbons and fatty acids) to study the sources and distribution of sedimentary organic matter. Concentrations of total organic carbon (TOC), total nitrogen (TN) and stable isotopic ratios of carbon (δ(13)C) ranged from 0.62 to 2.74 %, 0.09 to 0.25 % and -27.5 to 21.7 ‰, respectively. Sedimentary n-alkanes ranged from 6.03 to 43.23 μg g(-1) with an average of 16.79 μg g(-1), while total fatty acids varied from 22.55 to 440.69 μg g(-1). The TOC/TN ratios and δ(13)C suggest a mixture of marine- and terrestrial-derived organic matter in the surface sediments with increasing contributions from marine-derived organic matter towards the seaward side. Long-chain n-alkanes derived from higher plants predominated the inner part of the estuary, while short-chain n-alkanes derived from planktonic sources predominated the bar mouth region. The even carbon preference of the C12-C22 n-alkanes may refer to the direct biogenic contribution from bacteria, fungi and yeast species and to the potential direct petroleum inputs. The presence of odd mid-chain n-alkanes in the sediments indicates the organic matter inputs from submerged and floating macrophytes (water hyacinth). Various molecular indices such as carbon preference index, terrestrial to aquatic ratio, average chain length and the ratios of mid-chain n-alkanes support the aforementioned inferences. The high contribution of odd and branched chain fatty acids along with very low contribution of polyunsaturated fatty acids, suggest the effective utilisation of algae-derived organic matter by bacteria and the effective recycling of labile organic matter in whole settling and deposition processes. The distributional variability of n-alkanes and fatty acids reveals the preferential utilisation of marine-derived organic matter and the selective preservation of terrestrial-derived organic matter in surface sediments of the Cochin estuary.

Innovative eco-friendly bio- solvent for combating sea surface and sedimented oil pollution

NASA Astrophysics Data System (ADS)

Theodorou, Paraskevas

2017-04-01

The combating of oil spill at sea surface by chemical dispersants accelerates the evaporation and disperse the oil into the water column, where it is broken down by natural processes and/or is sedimented at the sea bottom, especially at near coastal shallow areas, ports and marinas. The usual methodology for cleaning the sedimented oil from the sea bottom is mainly carried out via excavation and dumping of the polluted sediment into deeper sea areas, where the contamination is transferred from one area to another. The eco-friendly bio-solvent MSL Aqua 250 is an innovative new solution based mainly on natural constituents. The action mechanism and the effectiveness of this eco-friendly solvent is based on the high surface tension process. Organic compounds, including hydrocarbons upon coming in contact with MSL Aqua 250 solvent generate a significant surface tension reaction, which is able to alter the organic compounds to liquid form and then to drastically evaporate it. The use of MSL Aqua 250 solvent, both at sea surface and at the bottom, has the following advantages compared to the dispersants: • Efficient solution without transferring the pollution from sea surface to the water column and to the bottom or disturbing the Aquatic Eco System. • Non-Toxic. • Environmentally friendly with a restoration of marine life in the Eco System. • Cost effective. The MSL Aqua 250 solvent has been tested in cooperation with the Cyprus Department of Fisheries and Marine Research and the Technological University of Cyprus and used during the years 2015 and 2016 in marinas and fishing shelters in Cyprus faced oil pollution, with high concentration in the sea water and at the sea bottom of chemical parameters (BOD5, COD, FOG, TKN, TP, TPH), with excellent results.

Distribution of branched GDGTs in surface sediments from the Colville River, Alaska: Implications for the MBT'/CBT paleothermometer in Arctic marine sediments

NASA Astrophysics Data System (ADS)

Hanna, Andrea J. M.; Shanahan, Timothy M.; Allison, Mead A.

2016-07-01

Significant climate fluctuations in the Arctic over the recent past, and additional predicted future temperature changes, highlight the need for high-resolution Arctic paleoclimate records. Arctic coastal environments supplied with terrigenous sediment from Arctic rivers have the potential to provide annual to subdecadal resolution records of climate variability over the last few millennia. A potential tool for paleotemperature reconstructions in these marine sediments is the revised methylation index of branched tetraethers (MBT')/cyclization ratio of branched tetraethers (CBT) proxy based on branched glycerol dialkyl glycerol tetraethers (brGDGTs). In this study, we examine the source of brGDGTs in the Colville River, Alaska, and the adjacent Simpson Lagoon and reconstruct temperatures from Simpson Lagoon sediments to evaluate the applicability of this proxy in Arctic estuarine environments. The Colville catchment soils, fluvial sediments, and estuarine sediments contain statistically similar brGDGT distributions, indicating that the brGDGTs throughout the system are soil derived with little alteration from in situ brGDGT production in the river or coastal waters. Temperatures reconstructed from the MBT'/CBT indices for surface samples show good agreement with regional summer (June through September) temperatures, suggesting a seasonal bias in Arctic temperature reconstructions from the Colville system. In addition, we reconstruct paleotemperatures from an estuarine sediment core that spans the last 75 years, revealing an overall warming trend in the twentieth century that is consistent with trends observed in regional instrumental records. These results support the application of this brGDGT-based paleotemperature proxy for subdecadal-scale summer temperature reconstructions in Arctic estuaries containing organic material derived from sediment-laden, episodic rivers.

Polybrominated, polychlorinated and monobromo-polychlorinated dibenzo-p-dioxins/dibenzofurans and dioxin-like polychlorinated biphenyls in marine surface sediments from Hong Kong and Korea.

PubMed

Terauchi, Hidenori; Takahashi, Shin; Lam, Paul K S; Min, Byung-Yoon; Tanabe, Shinsuke

2009-03-01

In this study we investigated occurrences and distribution patterns of dioxin-related compounds (DRCs) such as polybrominated dibenzo-p-dioxins/dibenzofurans (PBDD/Fs), polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), monobromo-polychlorinated dibenzo-p-dioxins/dibenzofurans (MoBPCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in marine surface sediments collected from the coastal waters of Hong Kong and Korea. In most sampling sites, concentrations of PCDDs were the highest, followed by DL-PCBs, PCDFs, PBDFs, PBDDs, MoBPCDDs and MoBPCDFs in this order. Levels of PBDD/Fs were generally 1-2 orders of magnitude lower than chlorinated analogues. Levels of PCDDs are higher than PCDFs in Hong Kong while levels of PBDFs are higher than PBDDs in Korea (p<0.05). Report of PBDD/Fs and MoBPCDD/Fs in sediments from East Asian countries is novel and original. Environmental levels of PBDD/Fs are supposed to start increasing in accordance with rising production, use and disposal of brominated flame retardants (BFRs) and recycling processes of e-waste in Asian developing countries.

Germanium Isotopes - the Global Budget and Paleoceanographic Potential

NASA Astrophysics Data System (ADS)

Baronas, J. J.; Hammond, D. E.; Rouxel, O. J.

2017-12-01

The distribution of element isotope ratios in rocks, sediments, rivers, and seawater can provide key insights about the operation and coupling of various biogeochemical cycles that are directly or indirectly responsible for the climate and habitability of the Earth surface environment. Germanium (Ge) is a trace element that shares many chemical similarities with silicon (Si), in addition to some siderophilic, chalcophilic, and organophilic properties. As a result, Ge stable isotope ratios (δ74Ge) and Ge/Si ratios can be used to trace various biogeochemical processes. These include silicate rock weathering, which modulates atmospheric pCO2 and supplies nutrients to ecosystems, biogenic silica formation, which is coupled to ocean productivity, and marine sediment diagenesis, which ultimately controls the removal of material from the Earth's surface. I will present an overview of my dissertation research concerning the global Ge isotope cycle, with insights into Ge isotope fractionation during secondary mineral precipitation during weathering on continents and during authigenesis in marine sediments. I will also discuss the potential for the δ74Ge sedimentary record to be used as a paleoceanographic proxy, given the constraints on the global Ge isotope budget.

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

NASA Astrophysics Data System (ADS)

Fang, J.

2015-12-01

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

Bioturbating shrimp alter the structure and diversity of bacterial communities in coastal marine sediments.

PubMed

Laverock, Bonnie; Smith, Cindy J; Tait, Karen; Osborn, A Mark; Widdicombe, Steve; Gilbert, Jack A

2010-12-01

Bioturbation is a key process in coastal sediments, influencing microbially driven cycling of nutrients as well as the physical characteristics of the sediment. However, little is known about the distribution, diversity and function of the microbial communities that inhabit the burrows of infaunal macroorganisms. In this study, terminal-restriction fragment length polymorphism analysis was used to investigate variation in the structure of bacterial communities in sediment bioturbated by the burrowing shrimp Upogebia deltaura or Callianassa subterranea. Analyses of 229 sediment samples revealed significant differences between bacterial communities inhabiting shrimp burrows and those inhabiting ambient surface and subsurface sediments. Bacterial communities in burrows from both shrimp species were more similar to those in surface-ambient than subsurface-ambient sediment (R=0.258, P<0.001). The presence of shrimp was also associated with changes in bacterial community structure in surrounding surface sediment, when compared with sediments uninhabited by shrimp. Bacterial community structure varied with burrow depth, and also between individual burrows, suggesting that the shrimp's burrow construction, irrigation and maintenance behaviour affect the distribution of bacteria within shrimp burrows. Subsequent sequence analysis of bacterial 16S rRNA genes from surface sediments revealed differences in the relative abundance of bacterial taxa between shrimp-inhabited and uninhabited sediments; shrimp-inhabited sediment contained a higher proportion of proteobacterial sequences, including in particular a twofold increase in Gammaproteobacteria. Chao1 and ACE diversity estimates showed that taxon richness within surface bacterial communities in shrimp-inhabited sediment was at least threefold higher than that in uninhabited sediment. This study shows that bioturbation can result in significant structural and compositional changes in sediment bacterial communities, increasing bacterial diversity in surface sediments and resulting in distinct bacterial communities even at depth within the burrow. In an area of high macrofaunal abundance, this could lead to alterations in the microbial transformations of important nutrients at the sediment-water interface.

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

PubMed

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 the development of biodispersants to be used in combatting marine oil spills.

Variations in sediment texture on the northern Monterey Bay National Marine Sanctuary continental shelf

USGS Publications Warehouse

Edwards, B.D.

2002-01-01

The storm-protected continental shelf of Monterey Bay, part of the Monterey Bay National Marine Sanctuary, north-central California, is subject to abundant, episodic sediment input from fluvial sources. North of Monterey Bay, conditions of reduced sediment supply combined with the exposed nature of the shelf provide an effective laboratory for studying the contrasting effects of storm- versus fluvial-dominated conditions on modern sedimentation. Textural analyses performed on surface sediment samples collected from more than 380 box cores and MultiCores??? document the existence of a clearly defined mud belt occupying the mid-shelf throughout the region. Inshore sands combined with these mid-shelf muds represent deposits from modern sedimentation processes. In Monterey Bay, where episodic fluvial input from winter storms dominates sedimentation, the mid-shelf mud belt extends across the shelf to the shelf break. North of Monterey Bay, where sediment loads are reduced and both oceanographic and storm processes dominate, the mid-shelf mud belt is bordered by relict sediments occupying the outer shelf. In the study area, mass accumulation rates established by radiochemical studies support the contention that storm-induced along-shelf processes result in northward transport of sediment within the mud belt. The continuity of transport, however, is interrupted by topographic highs which are barriers or inhibitors to sediment transport created by wrench-style tectonics associated with the San Andreas fault system.

A buried marine depositional sequence (Presumpscot FM. ) N. of the marine limit, Waterboro, Maine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morency, R.E.

Subsurface investigations conducted in Waterboro, ME (York Co.) in connection with studies of two hazardous waste sites and a municipal water supply exploration project, have demonstrated that a laterally extensive sequence of marine deposits underlies surficial sediments mapped as non-esker ice contact glacio-fluvial deposits. The marine deposits consist of a fining-downwards sequence of grey, micaceous sands (fine to medium, grading down to a silty-fine sand), which grade downward into a thick ([plus minus] 30 feet) grey silt/clay unit, which itself shows a fining-downward trend. The stratigraphy is likely correlative to the Presumpscot Formation, as described by Bloom (1963). The bottommore » of the regressive marine sequence is marked at several locations by a thin layer of sand-sized biotite mica. Lodgement till was encountered only at scattered localities (in boreholes) at each site. The bedrock surface is of considerable relief, with changes of 200--300 feet over short distances detected. The sequence appears to be the record of a rapidly transgressing sea which inundated a valley where outwash had been deposited by meltwater ahead of retreating ice. As the sea retreated, up to 70 feet of sediment was deposited in a continuous, coarsening-upwards sequence. Subsequent to the marine regression, the sediments were reworked in a subaerial (braided stream) environment. The Surficial Geologic Map of Maine shows that the inland limit of late-glacial marine submergence is located approximately 8 miles southwest of Waterboro, in Alfred, Maine. The marine limit in Alfred takes the form of a NNE trending, blunt-ended embayment. The results of this study suggest that the marine embayment once extended northward from Alfred, and is now a buried feature, possibly representing a preglacial valley, which hosted an estuary in late Wisconsonian time.« less

The Rusty Sink: Iron Promotes the Preservation of Organic Matter in Sediments

NASA Astrophysics Data System (ADS)

Lalonde, K. M.; Mucci, A.; Moritz, A.; Ouellet, A.; Gelinas, Y.

2011-12-01

The biogeochemical cycles of iron (Fe) and organic carbon (OC) are strongly interlinked. In oceanic waters, organic ligands have been shown to control the concentration of dissolved Fe [1], whereas in soils, solid Fe phases provide a sheltering and preservative effect for organic matter [2]. Until now however, the role of iron in the preservation of OC in sediments has not been clearly established. Here we show that 21.5 ± 8.6% of the OC in sediments is directly bound to reactive iron phases, which promote the preservation of OC in sediments. Iron-bound OC represents a global mass of 19 to 45 × 10^15 g of OC in surface marine sediments. This pool of OC is different from the rest of sedimentary OC, with 13C and nitrogen-enriched organic matter preferentially bound to Fe which suggests that biochemical fractionation occurs with OC-Fe binding. Preferential binding also affects the recovery of high molecular weight lipid biomarkers and acidic lignin oxidation products, changing the environmental message of proxies derived from these biomarkers. [1] Johnson, K. S., Gordon, R. M. & Coale, K. H. What controls dissolved iron in the world ocean? Marine Chemistry 57, 137-161 (1997). [2] Kaiser, K. & Guggenberger, G. The role of DOM sorption to mineral surfaces in the preservation of organic matter in soils. Organic Geochemistry 31, 711-725 (2000).

Clay mineral continental amplifier for marine carbon sequestration in a greenhouse ocean

PubMed Central

Kennedy, Martin J.; Wagner, Thomas

2011-01-01

The majority of carbon sequestration at the Earth’s surface occurs in marine continental margin settings within fine-grained sediments whose mineral properties are a function of continental climatic conditions. We report very high mineral surface area (MSA) values of 300 and 570 m2 g in Late Cretaceous black shales from Ocean Drilling Program site 959 of the Deep Ivorian Basin that vary on subcentennial time scales corresponding with abrupt increases from approximately 3 to approximately 18% total organic carbon (TOC). The observed MSA changes with TOC across multiple scales of variability and on a sample-by-sample basis (centimeter scale), provides a rigorous test of a hypothesized influence on organic carbon burial by detrital clay mineral controlled MSA. Changes in TOC also correspond with geochemical and sedimentological evidence for water column anoxia. Bioturbated intervals show a lower organic carbon loading on mineral surface area of 0.1 mg-OC m-2 when compared to 0.4 mg-OC m-2 for laminated and sulfidic sediments. Although either anoxia or mineral surface protection may be capable of producing TOC of < 5%, when brought together they produced the very high TOC (10–18%) apparent in these sediments. This nonlinear response in carbon burial resulted from minor precession-driven changes of continental climate influencing clay mineral properties and runoff from the African continent. This study identifies a previously unrecognized land–sea connection among continental weathering, clay mineral production, and anoxia and a nonlinear effect on marine carbon sequestration during the Coniacian-Santonian Oceanic Anoxic Event 3 in the tropical eastern Atlantic. PMID:21576498

Sedimentation of oil-derived material to the seabed is an unrecognized fate for oil derived from natural seepage.

NASA Astrophysics Data System (ADS)

Joye, S. B.

2016-02-01

The fate of oil derived from natural seepage in the marine environment is poorly constrained. In the aftermath of the 2010 BP/Macondo oil well blowout, sedimentation of oil-containing material to the seafloor was an important fate for discharged oil. Though the amount of oil accounted for by sedimentation processes remains poorly constrained, sedimentation is now considered an important fate of oil during large open water spills that generate extensive surface slicks. In the Gulf of Mexico, vigorous natural oil seeps generate extensive, sometimes thick, surface slicks. In the case of highly active seeps, these surface oil slicks persist at the sea surface over the seep site a majority of the time. We investigated the fate of oil released through natural seepage and the potential for the sedimentation of surface-slick derived oil at two vigorous hydrocarbon seeps in the Gulf of Mexico, Green Canyon block 600 and block 767. Hydrocarbon analyses were performed on samples collected from oil vents at the seafloor, in surface slicks, and in sediments cores apparently containing sedimented oil. Sediment cores collected from both of these active seep sites away from known oil vents contained distinct (1-3 cm thick) layers that were brown in coloration and which displayed distinct sedimentology compared to deeper strata. The oil fingerprint was also different, suggesting this material was not the result of weathering during transit through the sediment column. Available data suggest that sedimentation of weathered oil also occurs at vigorous natural seeps. Detailed studies of the weathered oil sedimentation process at natural seeps will help reveal the mechanisms driving this phenomena and are important for understanding the fate of oil released during accidental discharges and spills.

Temporal and spatial trends of total petroleum hydrocarbons and heavy metals in the surface sediment of Caofeidian Sea Area, China from 2011 to 2016

NASA Astrophysics Data System (ADS)

Huang, Wei

2018-05-01

The temporal and spatial distribution of total petroleum hydrocarbons (TPH) and four heavy metals in the surface sediments of Caofeidian Sea Area during 2011–2016 was investigated. The sediment concentration of TPH, Cu, Zn, Pb and Cd were 10.07-186.4 mg/L, 16.5-84.9 mg/L, 11.1-135 mg/L, 6.8-24.6 mg/L, and 0.07-0.199 mg/L, respectively. The pollution level in Caofeidian sea area is lower than those in other area in China. These results reached the highest marine sediment quality standards in China, indicating that the sediment was fairly clean. In addition, TPH at all stations decreased during 2011-2016. The highest values obtained were at stations near the port areas and estuary region.

The effect of grain size and surface area on organic matter, lignin and carbohydrate concentration, and molecular compositions in Peru Margin sediments

USGS Publications Warehouse

Bergamaschi, B.A.; Tsamakis, E.; Keil, R.G.; Eglinton, T.I.; Montlucon, D.B.; Hedges, J.I.

1997-01-01

A C-rich sediment sample from the Peru Margin was sorted into nine hydrodynamically-determined grain size fractions to explore the effect of grain size distribution and sediment surface area on organic matter content and composition. The neutral monomeric carbohydrate composition, lignin oxidation product yields, total organic carbon, and total nitrogen contents were determined independently for each size fraction, in addition to sediment surface area and abundance of biogenic opal. The percent organic carbon and percent total nitrogen were strongly related to surface area in these sediments. In turn, the distribution of surface area closely followed mass distribution among the textural size classes, suggesting hydrodynamic controls on grain size also control organic carbon content. Nevertheless, organic compositional distinctions were observed between textural size classes. Total neutral carbohydrate yields in the Peru Margin sediments were found to closely parallel trends in total organic carbon, increasing in abundance among grain size fractions in proportion to sediment surface area. Coincident with the increases in absolute abundance, rhamnose and mannose increased as a fraction of the total carbohydrate yield in concert with surface area, indicating these monomers were preferentially represented in carbohydrates associated with surfaces. Lignin oxidation product yields varied with surface area when normalized to organic carbon, suggesting that the terrestrially-derived component may be diluted by sorption of marine derived material. Lignin-based parameters suggest a separate source for terrestrially derived material associated with sand-size material as opposed to that associated with silts and clays. Copyright ?? 1997 Elsevier Science Ltd.

The effect of grain size and surface area on organic matter, lignin and carbohydrate concentration, and molecular compositions in Peru Margin sediments

NASA Astrophysics Data System (ADS)

Bergamaschi, Brian A.; Tsamakis, Elizabeth; Keil, Richard G.; Eglinton, Timothy I.; Montluçon, Daniel B.; Hedges, John I.

1997-03-01

A C-rich sediment sample from the Peru Margin was sorted into nine hydrodynamically-determined grain size fractions to explore the effect of grain size distribution and sediment surface area on organic matter content and composition. The neutral monomeric carbohydrate composition, lignin oxidation product yields, total organic carbon, and total nitrogen contents were determined independently for each size fraction, in addition to sediment surface area and abundance of biogenic opal. The percent organic carbon and percent total nitrogen were strongly related to surface area in these sediments. In turn, the distribution of surface area closely followed mass distribution among the textural size classes, suggesting hydrodynamic controls on grain size also control organic carbon content. Nevertheless, organic compositional distinctions were observed between textural size classes. Total neutral carbohydrate yields in the Peru Margin sediments were found to closely parallel trends in total organic carbon, increasing in abundance among grain size fractions in proportion to sediment surface area. Coincident with the increases in absolute abundance, rhamnose and mannose increased as a fraction of the total carbohydrate yield in concert with surface area, indicating these monomers were preferentially represented in carbohydrates associated with surfaces. Lignin oxidation product yields varied with surface area when normalized to organic carbon, suggesting that the terrestrially-derived component may be diluted by sorption of marine derived material. Lignin-based parameters suggest a separate source for terrestrially derived material associated with sand-size material as opposed to that associated with silts and clays.

Comparative organic geochemistry of Indian margin (Arabian Sea) sediments: estuary to continental slope

NASA Astrophysics Data System (ADS)

Cowie, G.; Mowbray, S.; Kurian, S.; Sarkar, A.; White, C.; Anderson, A.; Vergnaud, B.; Johnstone, G.; Brear, S.; Woulds, C.; Naqvi, S. W.; Kitazato, H.

2014-02-01

Surface sediments from sites across the Indian margin of the Arabian Sea were analysed for their carbon and nitrogen compositions (elemental and stable isotopic), grain size distributions and biochemical indices of organic matter (OM) source and/or degradation state. Site locations ranged from the estuaries of the Mandovi and Zuari rivers to depths of ~ 2000 m on the continental slope, thus spanning nearshore muds and sands on the shelf and both the semi-permanent oxygen minimum zone (OMZ) on the upper slope (~ 200-1300 m) and the seasonal hypoxic zone that impinges on the shelf. Source indices showed mixed marine and terrigenous OM within the estuaries, and overwhelming predominance (80%+) of marine OM on the shelf and slope. Thus, riverine OM is heavily diluted by autochthonous marine OM and/or is efficiently remineralised within or immediately offshore of the estuaries. Any terrigenous OM that is exported appears to be retained in nearshore muds; lignin phenols indicate that the small terrigenous OM content of slope sediments is of different origin, potentially from rivers to the north. Organic C contents of surface shelf and slope sediments varied from < 0.5 wt % in relict shelf sands to over 7 wt % at slope sites within the OMZ, decreasing to ≤ 1 wt % at 2000 m. Major variability (~ 5 wt %) was found at slope sites within the OMZ of similar depth and near-identical bottom-water oxygen concentration. A strong relationship between organic C and sediment grain size was seen for sediments within the OMZ, but lower C loadings were found for sites on the shelf and below the OMZ. Diagenetic indices confirmed that lower C content below the OMZ is associated with greater extent of OM degradation, but that C-poor shelf sediments are not consistently more degraded than those within the OMZ. Together, the results indicate that OM enrichment on the upper slope can be explained by physical controls (winnowing and/or dilution) on the shelf and progressive OM degradation with increasing oxygen exposure below the OMZ. Reduced oxygen exposure may contribute to OM enrichment at some sites within the OMZ, but hydrodynamic processes are the overriding control on sediment OM distribution.

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

NASA Astrophysics Data System (ADS)

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

2014-12-01

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

Reevaluation of microplastics extraction efficiency with the aim of Munich Plastic Sediment Separator.

NASA Astrophysics Data System (ADS)

Zobkov, Mikhail; Esiukova, Elena; Grave, Aleksei; Khatmullina, Liliya

2017-04-01

Invading of microplastics into marine environment is known as a global ecological threat. Specific density of microplastics can vary significantly depending on a polymer type, technological processes of its production, additives, weathering, and biofouling. Plastic particles can sink or float on the sea surface, but with time, most of drifting plastics become negatively buoyant and sink to the sea floor due to biofouling or adherence of denser particles. As a result, the seabed becomes the ultimate repository for microplastic particles and fibres. A study of microplastics content in aquatic sediments is an important source of information about ways of their migration, sink and accumulation zones. The Munich Plastic Sediment Separator (MPSS), proposed by Imhoff et al. (2012), is considered as the most effective tool for microplastic extraction. However, we observed that the numbers of marine microplastics extracted with this tool from different kinds of bottom sediments were significantly underestimated. We examined the extraction efficiency of the MPSS by adding artificial reference particles (ARPs) to marine sediment sample before the extraction procedure. Extraction was performed by two different methods: the modified NOAA method and using the MPSS. The separation solution with specific density 1.5 g/ml was used. Subsequent cleaning, drying and microscope detection procedures were identical. The microplastics content was determined in supernatant fraction, in the bulk of the extraction solution, in spoil dump fraction of MPSS and in instrument wash-out. While the extraction efficiency from natural sediments of ARPs by the MPSS was really high (100% in most cases), the extraction efficiency of marine microplastics was up to 10 times lower than that obtained with modified NOAA method for the same samples. Less than 40% of the total marine microplastics content has been successfully extracted with the MPSS. Large amounts of marine microplastics were found in the spoil dump and in the bulk solution fractions of the MPSS. Changes in stirring and separation periods had weak impact on the extraction efficiency of ARPs and marine microplastics. Until now, we are unable to find effective working procedures for adequate extraction of marine microplastics with the MPSS. The MPSS was found to be a useful tool for microplastics extraction from large sediment samples for qualitative analysis and to obtain examination specimens. Applying the MPSS for quantitative microplastics analysis requires further testing and elaboration of standardized extraction procedures. The research is supported by the Russian Science Foundation, grant number 15-17-10020 (project MARBLE). Imhof, H. K., Schmid, J., Niessner, R., Ivleva, N. P., Laforsch, C. 2012. A novel, highly efficient method for the separation and quantification of plastic particles in sediments of aquatic environments. Limnology and Oceanography: Methods, 10(7), 524-537. DOI 10.4319/lom.2012.10.524

Holocene environmental changes recorded in Dicksonfjorden and Woodfjorden, Svalbard: impacts of global climate changes in a glacial-marine system

NASA Astrophysics Data System (ADS)

Joo, Y. J.; Nam, S. I.; Son, Y. J.; Forwick, M.

2017-12-01

Fjords in the Svalbard archipelago are characterized by an extreme environmental gradient between 1) the glacial system affected by tidewater glaciers and seasonal sea ice inside the fjords and 2) the warm Atlantic Water intrusion by the West Spitsbergen Current from open ocean. As sediment is largely supplied from the terrestrial source area exposed along the steep slopes of the fjords, the changes in the surface processes affected by glaciers are likely preserved in the sediments in the inner fjords. On the other hand, variations in the influence of the warm Atlantic Water in the marine realm (e.g. marine productivity) can be archived in the sediment deposited in the vicinity of the entrance to the fjords. Since the last deglaciation of the Svalbard-Barents ice sheet ( 13000 yrs BP), the Svalbard fjords have faced dramatic climate changes including the early Holocene Climate Optimum (HCO) and subsequent cooling that eventually led to the current cold and dry climate. We investigate the Holocene environmental changes in both terrestrial and marine realms based on stable isotopic and inorganic geochemical analyses of sediments deposited in Dicksonfjorden and Woodfjorden in the western and northern Spitsbergen, respectively. The two fjords are expected to provide intriguing information regarding how terrestrial and marine realms of the Arctic fjords system responded to regional and global climate changes. Being a branch of the larger Isfjorden, Dicksonfjorden penetrates deeply to the land, whereas Woodfjorden is rather directly connected to the open ocean. Accordingly, the results suggest that the Dicksonfjorden sediment records mainly terrestrial signals with marked fluctuations in sediment composition that coincide with major climate changes (e.g. HCO). On the contrary, the two Woodfjorden cores collected from different parts of the fjord exhibit contrasting results, likely illustrating differing response of terrestrial and marine realms to the climate changes in terms of behavior of tidewater glaciers and inflow of the warm West Spitsbergen Current and their possible interactions. This study aims to disentangle the interaction between the fjords and the global climate changes and provide a holistic view to the Arctic fjords system with strong environmental gradients.

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

PubMed

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

2016-09-15

The Gulf of Aqaba is of significant strategic and economic value to all gulf-bordering states, particularly to Jordan, where it provides Jordan with its only marine outlet. The Gulf is subject to a variety of impacts posing imminent ecological risk to its unique marine ecosystem. We attempted to investigate the status of metal pollution in the coastal sediments of the Jordanian Gulf of Aqaba. The distribution of Cd, Cr, Zn, Cu, Pb, Al, Fe, and Mn concentrations were determined in trapped and bottom-surface sediments at three selected sites at different depths. In addition, monthly sedimentation rates at varying water depths were also estimated at each sampling site using sediment traps. The high concentrations of Cd, Cr, Zn were recorded at the Phosphate Loading Birth (PLB) site followed by the Industrial Complex (IC) site indicating their dominant anthropogenic source (i.e., the contribution of industrial activities). However, Fe, Al, and Mn contents were related to inputs from the terrigenous (crustal) origin. Except for Al, Fe and Mn at the PLB site, the concentrations of metals exhibited a decreasing trend with increasing water depth (distance from the shoreline). The PLB site also showed the highest sedimentation rate which decreased with increasing water depth. The Enrichment factors (EFs) showed that Cd was the most enriched element in the sediment (indicating that Cd pollution is widespread), whereas the least enriched metal in sediments was Cu. EF values suggested that the coastal area is impacted by a combination of human and natural sources of metals, where the anthropogenic sources are intense in the PLB site (north of Gulf of Aqaba). The MSS area is potentially the least polluted, consistent with being a marine reserve. The IC sediments have been found to be impacted by human activities but less intensely compared to the PLB area. These results suggested that there are two sources of metals in sediments; the primary source is likely closer to PLB, while the secondary is nearby the IC. Copyright © 2016 Elsevier Ltd. All rights reserved.

Modern Deposition Rates and Patterns of Carbon Burial in Southern Fiordland, New Zealand

NASA Astrophysics Data System (ADS)

Ramirez, M. T.; Allison, M. A.; Vetter, L.; Cui, X.; Bianchi, T. S.; Smith, R. W.; Savage, C.; Schüller, S.

2016-02-01

Fjords have been recognized as a hotspot of organic carbon burial, as they accumulate a disproportionate quantity of organic carbon given their areal extent in comparison to other marine settings. However, organic carbon is buried in context with other biogenic and mineral sediments, so localized sedimentation processes play a critical role in determining rates of organic carbon burial. Therefore, it is important to assess the local sources and processes responsible for depositing inorganic sediment as a control on the burial of organic carbon. Here we evaluate three fjords in southern New Zealand that are not glaciated, with a sedimentary system that is dominantly controlled by terrigenous input at fjord heads, reworking of sediments over fjord-mouth sills, and landslide events from the steep fjord walls. Sediment cores were collected throughout the three southernmost fjord systems of Fiordland, New Zealand, and analyzed to determine sedimentary fabric, mass accumulation rates, and organic carbon content. Sediment mass accumulation rates from 210Pb geochronology range up to 500 mg/cm2/yr in proximal and distal areas of the fjords, with lower rates (below 200 mg/cm2/yr) in medial reaches, where terrestrial and marine sediment input is minimal. X-radiographs and 210Pb downcore activity trends show evidence of both mass wasting and surface-sediment bioturbation operating throughout the fjords. Percent organic carbon displays a negative correlation with mass accumulation rate and thickness of the sediment surface mixed layer. Rates of organic carbon accumulation ranged from 3.97 to 21.59 mg/cm2/yr, with a mean of 13.41 mg/cm2/yr. Organic carbon accumulation rates are dependent on the sediment accumulation rate and the percent organic carbon of the sediment. Our results highlight the importance of spatial variability in sedimentation processes and rates within fjords when evaluating organic carbon burial in these systems.

Integrated Assessment of Heavy Metal Pollution in the Surface Sediments of the Laizhou Bay and the Coastal Waters of the Zhangzi Island, China: Comparison among Typical Marine Sediment Quality Indices

PubMed Central

Zhuang, Wen; Gao, Xuelu

2014-01-01

The total concentrations and chemical forms of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in the surface sediments of the Laizhou Bay and the surrounding marine area of the Zhangzi Island (hereafter referred to as Zhangzi Island for short) were obtained and multiple indices and guidelines were applied to assess their contamination and ecological risks. The sedimentary conditions were fine in both of the two studied areas according to the marine sediment quality of China. Whereas the probable effects level guideline suggested that Ni might cause adverse biological effects to occur frequently in some sites. All indices used suggested that Cd posed the highest environmental risk in both the Laizhou Bay and the Zhangzi Island, though Cd may unlikely be harmful to human and ecological health due to the very low total concentrations. The enrichment factor (EF) showed that a substantial portion of Cr was delivered from anthropogenic sources, whereas the risk assessment code (RAC) indicated that most Cr was in an inactive state that it may not have any adverse effect either. Moreover, the results of EF and geoaccumulation index were consistent with the trend of the total metal concentrations except for Cd, while the results of RAC and potential ecological risk factor did not follow the same trend of their corresponding total metal concentrations. We also evaluated the effects of using different indices to assess the environmental impact of these heavy metals. PMID:24709993

Radioactive contamination in the marine environment adjacent to the outfall of the radioactive waste treatment plant at ATOMFLOT, northern Russia.

PubMed

Brown, J E; Nikitin, A; Valetova, N K; Chumichev, V B; Katrich, I Yu; Berezhnoy, V I; Pegoev, N N; Kabanov, A I; Pichugin, S N; Vopiyashin, Yu Ya; Lind, B; Grøttheim, S; Sickel, M; Strand, P

2002-01-01

RTP "ATOMFLOT" is a civilian nuclear icebreaker base located on the Kola Bay of northwest Russia. The objectives of this study were to determine the distributions of man-made radionuclides in the marine environment adjacent to the base, to explain the form of the distributions in sediments and to derive information concerning the fate of radionuclides discharged from ATOMFLOT. Mean activity concentrations (d.w.) for surface sediment, of 63 Bq kg(-1 137Cs, 5.8 Bq kg(-1) 90Sr and 0.45 Bq kg(-1 239,240)Pu were measured. Filtered seawater activity levels were in the range of 3--6.9 Bq m(-3) 137Cs, 2.0-11.2 Bq m(-3) 90Sr, and 16-40 m Bq m(-3), 239,240Pu. Short-lived radionuclides were present at sediment depths in excess of 10cm indicating a high degree of sediment mixing. Correlations of radionuclide activity concentrations with grain-size appear to be absent; instead, the presence of relatively contaminated sediment appears to be related to the existence of radioactive particles.

Impact of Polymer Colonization on the Fate of Organic Contaminants in Sediment.

PubMed

Wu, Chen-Chou; Bao, Lian-Jun; Liu, Liang-Ying; Shi, Lei; Tao, Shu; Zeng, Eddy Y

2017-09-19

Plastic pellets and microbes are important constitutes in sediment, but the significance of microbes colonizing on plastic pellets to the environmental fate and transport of organic contaminants has not been adequately recognized and assessed. To address this issue, low-density polyethylene (LDPE), polyoxymethylene (POM) and polypropylene (PP) slices were preloaded with dichlorodiphenyltrichloroethanes (DDTs), polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) and incubated in abiotic and biotic sediment microcosms. Images from scanning electron microscope, Lysogeny Broth agar plates and confocal laser scanning microscope indicated that all polymer slices incubated in biotic sediments were colonized by microorganisms, particularly the LDPE slices. The occurrence of biofilms induced higher dissipation rates of DDTs and PAHs from the LDPE slice surfaces incubated in the biotic sediments than in the abiotic sediments. Plastic colonization on LDPE slice surfaces enhanced the biotransformation of DDT and some PAHs in both marine and river sediments, but had little impact on PCBs. By comparison, PP and POM with unique properties were shown to exert different impacts on the physical and microbial activities as compared to LDPE. These results clearly demonstrated that the significance of polymer surface affiliated microbes to the environmental fate and behavior of organic contaminants should be recognized.

Middle Holocene Organic Carbon and Biomarker Records from the South Yellow Sea: Relationship to the East Asian Monsoon

NASA Astrophysics Data System (ADS)

Zou, Liang; Hu, Bangqi; Li, Jun; Dou, Yanguang; Xie, Luhua; Dong, Liang

2018-03-01

The East Asian monsoon system influences the sedimentation and transport of organic matter in East Asian marginal seas that is derived from both terrestrial and marine sources. In this study, we determined organic carbon (OC) isotope values, concentrations of marine biomarkers, and levels of OC and total nitrogen (TN) in core YSC-1 from the central South Yellow Sea (SYS). Our objectives were to trace the sources of OC and variations in palaeoproductivity since the middle Holocene, and their relationships with the East Asian monsoon system. The relative contributions of terrestrial versus marine organic matter in core sediments were estimated using a two-end-member mixing model of OC isotopes. Results show that marine organic matter has been the main sediment constituent since the middle Holocene. The variation of terrestrial organic carbon concentration (OCter) is similar to the EASM history. However, the variation of marine organic carbon concentration (OCmar) is opposite to that of the EASM curve, suggesting OCmar is distinctly influenced by terrestrial material input. Inputs of terrestrial nutrients into the SYS occur in the form of fluvial and aeolian dust, while concentrations of nutrients in surface water are derived mainly from bottom water via the Yellow Sea circulation system, which is controlled by the East Asian winter monsoon (EAWM). Variations in palaeoproductivity represented by marine organic matter and biomarker records are, in general, consistent with the recent EAWM intensity studies, thus, compared with EASM, EAWM may play the main role to control the marine productivity variations in the SYS.

Controls of tectonics and sediment source locations on along-strike variations in transgressive deposits on the northern California margin

USGS Publications Warehouse

Spinelli, G.A.; Field, M.E.

2003-01-01

We identify two surfaces in the shallow subsurface on the Eel River margin offshore northern California, a lowstand erosion surface, likely formed during the last glacial maximum, and an overlying surface likely formed during the most recent transgression of the shoreline. The lowstand erosion surface, which extends from the inner shelf to near the shelfbreak and from the Eel River to Trinidad Head (???80 km), truncates underlying strata on the shelf. Above the surface, inferred transgressive coastal and estuarine sedimentary units separate it from the transgressive surface on the shelf. Early in the transgression, Eel River sediment was likely both transported down the Eel Canyon and dispersed on the slope, allowing transgressive coastal sediment from the smaller Mad River to accumulate in a recognizable deposit on the shelf. The location of coastal Mad River sediment accumulation was controlled by the location of the paleo-Mad River. Throughout the remainder of the transgression, dispersed sediment from the Eel River accumulated an average of 20 m of onlapping shelf deposits. The distribution and thickness of these transgressive marine units was strongly modified by northwest-southeast trending folds. Thick sediment packages accumulated over structural lows in the lowstand surface. The thinnest sediment accumulations (0-10 m) were deposited over structural highs along faults and uplifting anticlines. The Eel margin, an active margin with steep, high sediment-load streams, has developed a thick transgressive systems tract. On this margin sediment accumulates as rapidly as the processes of uplift and downwarp locally create and destroy accommodation space. Sequence stratigraphic models of tectonically active margins should account for variations in accommodation space along margins as well as across them. ?? 2003 Elsevier Science B.V. All rights reserved.

20th-century glacial-marine sedimentation in Vitus Lake, Bering Glacier, Alaska, U.S.A.

USGS Publications Warehouse

Molnia, B.F.; Post, A.; Carlson, P.R.

1996-01-01

Vitus Lake, the ice-marginal basin at the southeastern edge of Bering Glacier, Alaska, U.S.A., is a site of modern, rapid, glacial-marine sedimentation. Rather than being a fresh-water lake, Vitus Lake is a tidally influenced, marine to brackish embayment connected to the Pacific Ocean by an inlet, the Seal River. Vitus Lake consists of five deep bedrock basins, separated by interbasinal highs. Glacial erosion has cut these basins as much as 250 m below sea level. High-resolution seismic reflection surveys conducted in 1991 and 1993 of four of Vitus Lake's basins reveal a complex, variable three-component acoustic stratigraphy. Although not fully sampled, the stratigraphy is inferred to be primarily glacial-marine units of (1) basal contorted and deformed glacial-marine and glacial sediments deposited by basal ice-contact processes and submarine mass-wasting; (2) acoustically well-stratified glacial-marine sediment, which unconformably overlies the basal unit and which grades upward into (3) acoustically transparent or nearly transparent glacial-marine sediment. Maximum thicknesses of conformable glacial-marine sediment exceed 100 m. All of the acoustically transparent and stratified deposits in Vitus Lake are modern in age, having accumulated between 1967 and 1993. The basins where these three-part sequences of "present-day" glacial-marine sediment are accumulating are themselves cut into older sequences of stratified glacial and glacial-marine deposits. These older units outcrop on the islands in Vitus Lake. In 1967, as the result of a major surge, glacier ice completely filled all five basins. Subsequent terminus retreat, which continued through August 1993, exposed these basins, providing new locations for glacial-marine sediment accumulation. A correlation of sediment thicknesses measured from seismic profiles at specific locations within the basins, with the year that each location became ice-free, shows that the sediment accumulation at some locations exceeds 10 m year-1.

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

NASA Astrophysics Data System (ADS)

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

1994-11-01

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

Acid-volatile sulfide and simultaneously extracted metals in surface sediments of the southwestern coastal Laizhou Bay, Bohai Sea: concentrations, spatial distributions and the indication of heavy metal pollution status.

PubMed

Zhuang, Wen; Gao, Xuelu

2013-11-15

Surface sediments were collected from the coastal waters of southwestern Laizhou Bay and the rivers it connects with during summer and autumn 2012. The acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) were measured to assess the sediment quality. The results showed that not all sediments with [SEM]-[AVS]>0 were capable of causing toxicity because the organic carbon is also an important metal-binding phase in sediments. Suppose the sediments had not been disturbed and the criteria of US Environmental Protection Agency had been followed, heavy metals in this area had no adverse biological effects in both seasons except for few riverine samples. The major ingredient of SEM was Zn, whereas the contribution of Cd - the most toxic metal studied - to SEM was <1%. The distributions of AVS and SEM in riverine sediments were more easily affected by anthropogenic activity compared with those in marine sediments. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of triclosan on marine benthic and epibenthic organisms.

PubMed

Perron, Monique M; Ho, Kay T; Cantwell, Mark G; Burgess, Robert M; Pelletier, Marguerite C

2012-08-01

Triclosan is an antimicrobial compound that has been widely used in consumer products such as toothpaste, deodorant, and shampoo. Because of its widespread use, triclosan has been detected in various environmental media, including wastewater, sewage sludge, surface waters, and sediments. Triclosan is acutely toxic to numerous aquatic organisms, but very few studies have been performed on estuarine and marine benthic organisms. For whole sediment toxicity tests, the sediment-dwelling estuarine amphipod, Ampelisca abdita, and the epibenthic mysid shrimp, Americamysis bahia, are commonly used organisms. In the present study, median lethal concentration values (LC50) were obtained for both of these organisms using water-only and whole sediment exposures. Acute 96-h water-only toxicity tests resulted in LC50 values of 73.4 and 74.3 µg/L for the amphipod and mysid, respectively. For the 7-d whole sediment toxicity test, LC50 values were 303 and 257 mg/kg (dry wt) for the amphipod and mysid, respectively. Using equilibrium partitioning theory, these whole sediment values are equivalent to interstitial water LC50 values of 230 and 190 µg/L for the amphipod and mysid, respectively, which are within a threefold difference of the observed 96-h LC50 water-only values. Triclosan was found to accumulate in polychaete tissue in a 28-d bioaccumulation study with a biota-sediment accumulation factor of 0.23 kg organic carbon/kg lipid. These data provide some of the first toxicity data for triclosan with marine benthic and epibenthic species while also indicating a need to better understand the effects of other forms of sediment carbon, triclosan ionization, and organism metabolism of triclosan on the chemical's behavior and toxicity in the aquatic environment. Copyright © 2012 SETAC.

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

NASA Astrophysics Data System (ADS)

Zoppini, Annamaria; Ademollo, Nicoletta; Amalfitano, Stefano; Dellisanti, Walter; Lungarini, Silvia; Miserocchi, Stefano; Patrolecco, Luisa; Langone, Leonardo

2015-04-01

PERSEUS EU FP7 Project aims to identify the interacting patterns of natural and human-derived pressures to assess their impact on marine ecosystems and, using the objectives and principles of the Marine Strategy Framework Directive (MSFD) as a vehicle, to design an effective and innovative research governance framework based on sound scientific knowledge. In the frame of this Project (subtask 1.3.3 ADREX: Adriatic and Ionian Seas Experiment), monitoring surveys were conducted in the Adriatic Sea (Italy) in order to study the variation of structural and functional characteristics of native bacterial communities and the occurrence of selected classes of organic priority substances in sediments. The study area represents a good natural laboratory sensitive to climate variability and human pressure, owing to the semi-enclosed nature of the Adriatic Sea and to the increasing trend of human activities in the coastal regions. During the cruise ADRI-13 (November 2013) and ADRI-14 (October 2014) we sampled several coastal sites from the mouth of the Po River to the Otranto strait. Surface sediments were collected in all areas, while sediment cores were sampled in selected sites. Microbes associated with marine sediments play an important role in the C-flux being responsible for the transformation of organic detritus (autochthonous and allochthonous) into biomass. The sediment bacterial abundance was determined by epifluorescence microscopy and the rate of bacterial carbon production by measuring the 3H-leucine uptake rates. The community respiration rate was estimated by the measurement of the electron transport system (ETS) activity. The sediment contamination level was determined by measuring the concentration of contaminants included in the list of organic priority substances: PAHs, bisphenol A (BPA), alkylphenols (APs). The extraction/clean-up of PAHs, BPA and APs was performed by ultrasonic bath with the appropriate solvents, followed by analytical determination with LC-MS or HPLC UV-fluorescence. The joint analysis of the microbial properties and the concentration of the organic pollutants reflects the impact of anthropic pressure on the selected coastal areas. At the surface layers, the microbial carbon assimilation and mineralization rates were affected by the increasing concentration of pollutants. The highest concentrations of organic pollutants were detected in the deeper sediment layers (20 cm) where a significant reduction of microbial metabolic activities was observed. The results of this study can contribute to acquire information to improve the MSFD and to reach the good environmental status.

Nannofossil and sequence chronostratigraphy of a marine flooding surface in the Turonian of Trinidad

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, T.C.

1996-08-01

A multi-well regional study in the Southern basin, Trinidad, reveals a very pronounced marine flooding surface in Turonian- age sediments. This surface is correlatable with global Turonian marine transgressions and genetically ties with the best hydrocarbon source rocks known in Trinidad. The Turonian marine flooding surface yields abundant nannoplankton. Most notable is Lithastrinus moratus Stover, a short-ranging marker of the Lithastrinus evolutionary series. Two morphotypes of Lithastrinus moratus have been found. The more delicate eight-rayed form evolves from Lithastrinus floralls in early Turonian time. Based on observations in Ste. Croix-1, Rocky Palace-1, Rochard-1, Marac-1, Moniga East-15, Iguana River-1, Lizard Spring-Imore » and Antilles Brighton-102, it occurs more frequently in the lower Turonian, but is rare in Trinidad. It has a more robust seven-rayed descendant that appears to be restricted to a narrow interval associated with peak Turonian marine transgression and usually dominates the nannofossil assemblage in the condensed section. The highest stratigraphic occurrence of this form coincides with the lowest occurrence of Marthastentes furcatus based on core sample studies. The age of the marine flooding surface is therefore well constrained to be in zone CC12 and is considered to be correlative with the 89 million year marine flooding surface. The marine flooding surface appears intercontinentally correlatable as it has also been identified in the Arcadia Shale of the Eagle Ford Group in Texas. Because of its wide areal distribution and ease of paleontological recognition, this surface is ideal for regional hydrocarbon source rock mapping, stratal correlation and structural control.« less

Biosurfactant-induced remediation of contaminated marine sediments: Current knowledge and future perspectives.

PubMed

Dell'Anno, F; Sansone, C; Ianora, A; Dell'Anno, A

2018-06-01

The contamination of marine sediments is widespread in coastal regions of the world and represents a major concern for the potential detrimental consequences on ecosystems' health and provision of goods and services for human wellbeing. Thus, there is an urgent need to find sustainable and eco-compatible solutions for the remediation of contaminated sediments. Bioremediation is a low cost and environmental-friendly strategy with a high potential for the remediation of contaminated marine sediments. Here we review the potential application of biosurfactants produced by microbial taxa for the remediation of contaminated marine sediments and we discuss future research needs to develop efficient and eco-sustainable biosurfactant-based strategies for the recovery of contaminated marine sediments, in view of large-scale applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

Organic contamination of surface sediments in the metropolitan coastal zone of Athens, Greece: sources, degree, and ecological risk.

PubMed

Kapsimalis, V; Panagiotopoulos, I P; Talagani, P; Hatzianestis, I; Kaberi, H; Rousakis, G; Kanellopoulos, T D; Hatiris, G A

2014-03-15

Bottom sediments represent a crucial component of the marine environment, since they constitute a habitat, a trophic resource, and a spawning place for various organisms. Unfortunately, the sediments of urban coastal areas are deeply impacted by anthropogenic activities that degrade their quality. In the Drapetsona-Keratsini metropolitan coastal zone of Athens, current industrial and shipping activities together with the effluents from a sewage outfall, which was in operation in the past, have resulted in one of the most contaminated sedimentary environments, in terms of organic compound loads, in Mediterranean. Exceptionally high concentrations of aliphatic hydrocarbons (up to 4457 μg g⁻¹), carcinogenic PAHs (up to 7284 ng g⁻¹), and organochlorines (up to 544 ng g⁻¹ for PCBs; up to 208 ng g⁻¹ for DDTs) constitute a major threat to the marine life of the associated Saronikos Gulf. Copyright © 2013 Elsevier Ltd. All rights reserved.

Implications of dredging induced changes in sediment particle size composition for the structure and function of marine benthic macrofaunal communities.

PubMed

Cooper, K M; Curtis, M; Wan Hussin, W M R; Barrio Froján, C R S; Defew, E C; Nye, V; Paterson, D M

2011-10-01

A meta-analysis approach was used to assess the effect of dredging induced changes in sediment composition, under different conditions of natural physical disturbance, for the structure and function of marine benthic macrofaunal communities. Results showed the sensitivity of macrofaunal communities increased as both the proportion of gravel increased and the level of natural physical disturbance decreased. These findings may be explained by the close association of certain taxa with the gravel fraction, and the influence of natural physical disturbance which, as it increases, tends to restrict the colonisation by these species. We conclude that maintaining the gravel content of surface sediments after dredging and, where practicable, locating extraction sites in areas of higher natural disturbance will minimise the potential for long-term negative impacts on the macrofauna. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

Persistence of nonylphenol ethoxylate surfactants and their primary degradation products in sediments from near a municipal outfall in the Strait of Georgia, British Columbia, Canada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shang, D.Y.; Macdonald, R.W.; Ikonomou, M.G.

1999-05-01

Marine sediment cores and surface grabs were collected from the Strait of Georgia, British Columbia, Canada, near the Iona municipal outfall and were analyzed for nonylphenol (NP) and its ethoxylate compounds (NPnEOs). The authors used normal-phase liquid chromatography with electrospray mass spectrometric detection to determine concentrations of ethoxylates from n = 1 to n = 19. Over half the NPnEO inventory in marine sediments resides in ethoxylates of chain length greater than n = 2, suggesting that analyses limited to short-chain ethoxylates (n = 2) are under-reporting total NPnEO by a factor of 2. The NPnEO vertical profiles and oligomermore » distributions in dated sediment cores suggest that little degradation occurs once these compounds enter the sediments: the half-life for these compounds is estimated to be greater than 60 yr. The lack of change in NPnEO oligomer distribution with age suggests that degradation by chain shortening does not occur significantly. A rough inventory shows that over 30 t of NPnEO resides in Fraser River Delta sediments near the Iona municipal outfall and that the entire Strait of Georgia sediments contain over 170 t of NPnEO.« less

Integrated diagenetic and sequence stratigraphy of a late Oligocene-early Miocene, mixed-sediment platform (Austral Basin, southern Patagonia): Resolving base-level and paleoceanographic changes, and paleoaquifer characteristics

NASA Astrophysics Data System (ADS)

Dix, George R.; Parras, Ana

2014-06-01

A condensed (~ 20-m-thick) marine transgressive-highstand succession comprises the upper San Julián Formation (upper Oligocene-lower Miocene) of the northern retroarc Austral Basin, southern Patagonia. Mixed-sediment facies identify a shelf-interior setting, part of an overall warm-temperate regional platform of moderate energy. Giant oyster-dominated skeletal-hiatal accumulations along the maximum flooding surface and forming high-energy event beds in the highstand succession preserve relict micrite in protected shelter porosity, and identify periods of reduced sediment accumulation. The stratigraphic distribution of marine-derived glaucony and diagenetic carbonates is spatially related to sequence development. Depositional siderite coincides with prominent marine transgression, defining transient mixing of marine and meteoric waters across coastal-plain deposits. Chemically evolved autochthonous glaucony coincides with periods of extended seafloor exposure and transgressions that bracket the marine succession, and within the oyster-dominated skeletal accumulations. Seafloor cement, likely once magnesian calcite, formed in association with an encrusting/boring biota along the maximum flooding surface in concert with incursion of cool (11-13 °C) water. The cement is present locally in skeletal event beds in the highstand succession suggesting a possible association with high-order base-level change and cooler water. As the highstand succession coincides with elevated global sea level in the late Oligocene-early Miocene, the locally marine-cemented glauconitic skeletal event beds in the highstand succession may identify higher order glacio-eustatic control. Local stratal condensation, however, is best explained by regional differences in basement subsidence. In the burial realm, carbonate diagenesis produced layers of phreatic calcrete coincident with skeletal-rich deposits. Zeolite (clinoptilolite-K) cement is restricted to the lowermost marine transgressive interval probably due to initial elevated metastability of reworked weathered silicates. Clay (illite)-cement is restricted to siliciclastic-rich intervals wherein skeletal carbonate did not buffer pore-water pH. Diagenetic carbonate geochemistry (Sr, Na, and δ18O and δ13C) shows that, with burial, the transgressive and highstand system tracts developed as distinct paleoaquifers resulting from different proximities to meteoric recharge zones.

Enrichment of Fusobacteria in Sea Surface Oil Slicks from the Deepwater Horizon Oil Spill

PubMed Central

Gutierrez, Tony; Berry, David; Teske, Andreas; Aitken, Michael D.

2016-01-01

The Deepwater Horizon (DWH) oil spill led to rapid microbial community shifts in the Gulf of Mexico, including the formation of unprecedented quantities of marine oil snow (MOS) and of a massive subsurface oil plume. The major taxa that bloomed in sea surface oil slicks during the spill included Cycloclasticus, and to a lesser extent Halomonas, Alteromonas, and Pseudoalteromonas—organisms that grow and degrade oil hydrocarbons aerobically. Here, we show that sea surface oil slicks at DWH contained obligate and facultative anaerobic taxa, including members of the obligate anaerobic phylum Fusobacteria that are commonly found in marine sediment environments. Pyrosequencing analysis revealed that Fusobacteria were strongly selected for when sea surface oil slicks were allowed to develop anaerobically. These organisms have been found in oil-contaminated sediments in the Gulf of Mexico, in deep marine oil reservoirs, and other oil-contaminated sites, suggesting they have putative hydrocarbon-degrading qualities. The occurrence and strong selection for Fusobacteria in a lab-based incubation of a sea surface oil slick sample collected during the spill suggests that these organisms may have become enriched in anaerobic zones of suspended particulates, such as MOS. Whilst the formation and rapid sinking of MOS is recognised as an important mechanism by which a proportion of the Macondo oil had been transported to the sea floor, its role in potentially transporting microorganisms, including oil-degraders, from the upper reaches of the water column to the seafloor should be considered. The presence of Fusobacteria on the sea surface—a highly oxygenated environment—is intriguing, and may be explained by the vertical upsurge of oil that provided a carrier to transport these organisms from anaerobic/micro-aerophilic zones in the oil plume or seabed to the upper reaches of the water column. We also propose that the formation of rapidly-sinking MOS may have re-transported these, and other microbial taxa, to the sediment in the Gulf of Mexico. PMID:27681918

Environmental Impact of Tributyltin-Resistant Marine Bacteria in the Indigenous Microbial Population of Tributyltin-Polluted Surface Sediments.

PubMed

Mimura, Haruo; Yagi, Masahiro; Yoshida, Kazutoshi

2017-01-01

　We compared the TBT-resistant ability of resting cells prepared from isolates that formed colonies on nutrient agar plates containing 100 µM tributyltin (TBT) chloride, such as Photobacterium sp. TKY1, Halomonas sp. TKY2, and Photobacterium sp. NGY1, with those from taxonomically similar type strains. Photobacterium sp. TKY1 showed the highest ability among those three isolates. The number of surviving Photobacterium sp. TKY1 cells was hardly decreased after 1 h of exposure to 100 µM TBTCl, regardless of the number of resting cells in the range from 10 9.4 to 10 4.2 CFU mL -1 . In such an experimental condition, the maximum number of TBT molecules available to associate with a single cell was estimated to be approximately 6.0 x 10 11.8 . Resting cells prepared from type strains Photobacterium ganghwense JCM 12487 T and P. halotolerans LMG 22194 T , which have 16S rDNA sequences highly homologous with those of Photobacterium sp. TKY1, showed sensitivity to TBT, indicating that TBT-resistant marine bacterial species are not closely related in spite of their taxonomic similarity. We also estimated the impact of TBT-resistant bacterial species to indigenous microbial populations of TBT-polluted surface sediments. The number of surviving TBT-sensitive Vibrio natriegens ATCC 14048 T cells, 10 6.2±0.3 CFU mL -1 , was reduced to 10 4.4±0.4 CFU mL -1 when TBT-resistant Photobacterium sp. TKY1 cells, 10 9.1±0.2 CFU mL -1 , coexisted with 10 9.4±0.2 CFU mL -1 of V. natriegens ATCC 14048 T cells in the presence of 100 µM TBTCl. These results indicate that the toxicity of TBT to TBT-sensitive marine bacterial populations might be enhanced when a TBT-resistant marine bacterial species inhabits TBT-polluted surface sediments.

CO2 leakage from carbon dioxide capture and storage (CCS) systems affects organic matter cycling in surface marine sediments.

PubMed

Rastelli, Eugenio; Corinaldesi, Cinzia; Dell'Anno, Antonio; Amaro, Teresa; Greco, Silvestro; Lo Martire, Marco; Carugati, Laura; Queirós, Ana M; Widdicombe, Stephen; Danovaro, Roberto

2016-12-01

Carbon dioxide capture and storage (CCS), involving the injection of CO 2 into the sub-seabed, is being promoted worldwide as a feasible option for reducing the anthropogenic CO 2 emissions into the atmosphere. However, the effects on the marine ecosystems of potential CO 2 leakages originating from these storage sites have only recently received scientific attention, and little information is available on the possible impacts of the resulting CO 2 -enriched seawater plumes on the surrounding benthic ecosystem. In the present study, we conducted a 20-weeks mesocosm experiment exposing coastal sediments to CO 2 -enriched seawater (at 5000 or 20,000 ppm), to test the effects on the microbial enzymatic activities responsible for the decomposition and turnover of the sedimentary organic matter in surface sediments down to 15 cm depth. Our results indicate that the exposure to high-CO 2 concentrations reduced significantly the enzymatic activities in the top 5 cm of sediments, but had no effects on subsurface sediment horizons (from 5 to 15 cm depth). In the surface sediments, both 5000 and 20,000 ppm CO 2 treatments determined a progressive decrease over time in the protein degradation (up to 80%). Conversely, the degradation rates of carbohydrates and organic phosphorous remained unaltered in the first 2 weeks, but decreased significantly (up to 50%) in the longer term when exposed at 20,000 ppm of CO 2 . Such effects were associated with a significant change in the composition of the biopolymeric carbon (due to the accumulation of proteins over time in sediments exposed to high-pCO 2 treatments), and a significant decrease (∼20-50% at 5000 and 20,000 ppm respectively) in nitrogen regeneration. We conclude that in areas immediately surrounding an active and long-lasting leak of CO 2 from CCS reservoirs, organic matter cycling would be significantly impacted in the surface sediment layers. The evidence of negligible impacts on the deeper sediments should be considered with caution and further investigated simulating the intrusion of CO 2 from a subsurface source, as occurring during real CO 2 leakages from CCS sites. Copyright © 2016 Elsevier Ltd. All rights reserved.

That sinking feeling: Suspended sediments can prevent the ascent of coral egg bundles

PubMed Central

Ricardo, Gerard F.; Jones, Ross J.; Negri, Andrew P.; Stocker, Roman

2016-01-01

Spawning synchrony represents a common reproductive strategy in sessile marine organisms and for broadcast spawning corals, buoyancy of egg-sperm bundles is critical to maximise fertilisation at the ocean surface. Here we demonstrate a novel threat to coral reproduction whereby buoyant egg-sperm bundles intercept and are “ballasted” by sediment grains on their journey to the ocean surface, preventing them from reaching the ocean surface and greatly reducing egg-sperm encounter rates. Empirical observations of this mechanism are successfully captured by a mathematical model that predicts the reduction in ascent probability and egg-sperm encounters as a function of sediment load. When applied to 15 m deep reefs, the model predicts that 10% and 50% reductions in egg-sperm encounters occur at 35 mg L−1 and 87 mg L−1 suspended sediment concentrations, respectively, and for a 5 m deep reef a 10% reduction occurs at 106 mg L−1. These concentrations are commonly associated with sediment plumes from dredging or natural resuspension events. The potential for sediments to sink coral gametes highlights the need to carefully manage the timing of turbidity-generating human activities near reefs during spawning periods. PMID:26898352

That sinking feeling: Suspended sediments can prevent the ascent of coral egg bundles.

PubMed

Ricardo, Gerard F; Jones, Ross J; Negri, Andrew P; Stocker, Roman

2016-02-22

Spawning synchrony represents a common reproductive strategy in sessile marine organisms and for broadcast spawning corals, buoyancy of egg-sperm bundles is critical to maximise fertilisation at the ocean surface. Here we demonstrate a novel threat to coral reproduction whereby buoyant egg-sperm bundles intercept and are "ballasted" by sediment grains on their journey to the ocean surface, preventing them from reaching the ocean surface and greatly reducing egg-sperm encounter rates. Empirical observations of this mechanism are successfully captured by a mathematical model that predicts the reduction in ascent probability and egg-sperm encounters as a function of sediment load. When applied to 15 m deep reefs, the model predicts that 10% and 50% reductions in egg-sperm encounters occur at 35 mg L(-1) and 87 mg L(-1) suspended sediment concentrations, respectively, and for a 5 m deep reef a 10% reduction occurs at 106 mg L(-1). These concentrations are commonly associated with sediment plumes from dredging or natural resuspension events. The potential for sediments to sink coral gametes highlights the need to carefully manage the timing of turbidity-generating human activities near reefs during spawning periods.

Geochemistry of recent aragonite-rich sediments in Mediterranean karstic marine lakes: Trace elements as pollution and palaeoredox proxies and indicators of authigenic mineral formation.

PubMed

Sondi, Ivan; Mikac, Nevenka; Vdović, Neda; Ivanić, Maja; Furdek, Martina; Škapin, Srečo D

2017-02-01

This study investigates the geochemical characteristics of recent shallow-water aragonite-rich sediments from the karstic marine lakes located in the pristine environment on the island of Mljet (Adriatic Sea). Different trace elements were used as authigenic mineral formation, palaeoredox and pollution indicators. The distribution and the historical record of trace elements deposition mostly depended on the sedimentological processes associated with the formation of aragonite, early diagenetic processes governed by the prevailing physico-chemical conditions and on the recent anthropogenic activity. This study demonstrated that Sr could be used as a proxy indicating authigenic formation of aragonite in a marine carbonate sedimentological environment. Distribution of the redox sensitive elements Mo, Tl, U and Cd was used to identify changes in redox conditions in the investigated lake system and to determine the geochemical cycle of these elements through environmental changes over the last 100 years. The significant enrichment of these elements and the presence of early formed nanostructured authigenic framboidal pyrite in laminated deeper parts of sediment in Malo Jezero, indicate sporadic events of oxygen-depleted euxinic conditions in the recent past. Concentrations of trace elements were in the range characteristic for non-contaminated marine carbonates. However, the increase in the concentrations of Zn, Cu, Pb, Sn, Bi in the upper-most sediment strata of Veliko Jezero indicates a low level of trace element pollution, resulting from anthropogenic inputs over the last 40 years. The presence of butyltin compounds (BuTs) in the surface sediment of Veliko Jezero additionally indicates the anthropogenic influence in the recent past. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dispersion of Sound in Marine Sediments

DTIC Science & Technology

2015-09-30

primary objective of this work is to investigate the approach to use the information in the extracted mode amplitudes to invert for sound attenuation...marine sediment. APPROACH Previous work carried out on the use of modal amplitude information for estimating sound attenuation in the sediments...investigate the intrinsic modal interference. Estimation of sound attenuation in marine sediments from modal amplitudes requires knowledge of the

Petroleum hydrocarbons in a water-sediment system from Yellow River estuary and adjacent coastal area, China: Distribution pattern, risk assessment and sources.

PubMed

Wang, Min; Wang, Chuanyuan; Li, Yuanwei

2017-09-15

Aliphatic hydrocarbons (AHs), biomarker and polycyclic aromatic hydrocarbons (PAHs) concentrations of surface water and sediment samples collected from Yellow River Estuary and adjacent coastal area in China were measured to determine their spatial distributions, analyze their sources and evaluate the ecological risk of PAHs in the water-sediment system. The spatial distributions of n-alkane in sediments are mainly controlled by the mixing inputs of terrigenous and marine components. In comparison with AHs, the total concentrations of Σ16PAHs in surface sediments from a transect of the offshore area were noticeably higher than that of the riverine and estuary areas. Additionally, the AHs and total PAHs concentrations all indicated an overall pattern of a seaward decrease. The PAHs concentrations during the dry season (mainly in the form of dissolved phase) were higher than that of PAHs (mainly dissolved phase and particulate phase form) in the flooding season. In comparison with global concentration levels of PAHs, the level of PAHs in suspended particulate matter and sediments from the Yellow River Estuary was lower than those from other countries, while the concentration of PAHs in the dissolved phase were in the middle range. Petroleum contamination, mainly from oil exploration and discharge of pollutants from rivers, was the main source of n-alkanes. The PAHs in the river were mostly of petrogenic origin, while those in the estuarial and marine areas originated mainly from pyrogenic sources. The results of the toxicology assessment suggested that the PAHs in sediments from Yellow River Estuary and adjacent coastal area exhibited a low potential eco-toxicological contamination level. Copyright © 2017 Elsevier Ltd. All rights reserved.

A shift in the biogenic silica of sediment in the Larsen B continental shelf, off the Eastern Antarctic Peninsula, resulting from climate change.

PubMed

Sañé, Elisabet; Isla, Enrique; Bárcena, María Ángeles; DeMaster, David J

2013-01-01

In 2002, section B of the Larsen ice shelf, off of the Eastern Antarctic Peninsula, collapsed and created the opportunity to study whether the changes at the sea surface left evidence in the sedimentary record. Biogenic silica is major constituent of Antarctic marine sediment, and its presence in the sediment column is associated with diatom production in the euphotic zone. The abundance of diatom valves and the number of sponge spicules in the biogenic silica was analyzed to determine how the origin of the biogenic silica in the upper layers of the sediment column responded to recent environmental changes. Diatom valves were present only in the upper 2 cm of sediment, which roughly corresponds to the period after the collapse of the ice shelf. In contrast, sponge spicules, a more robust form of biogenic silica, were also found below the upper 2 cm layer of the sediment column. Our results indicate that in this region most of the biogenic silica in the sedimentary record originated from sponge spicules rather than diatoms during the time when the sea surface was covered by the Larsen ice shelf. Since the collapse of the ice shelf, the development of phytoplankton blooms and the consequent influx of diatom debris to the seabed have shifted the biogenic silica record to one dominated by diatom debris, as occurs in most of the Antarctic marine sediment. This shift provides further evidence of the anthropogenic changes to the benthic habitats of the Antarctic and will improve the interpretation of the sedimentary record in Polar Regions where these events occur.

Integrated biostratigraphic zonation for the Malay Basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yakzan, A.M.; Nasib, B.Md.; Harun, A.

1994-07-01

This study presents a detailed biostratigraphic scheme for the Malay Basin based on the examination of 10 wells by PRSS, and the review of data from 12 wells, which were previously studied by service companies. For each of the wells reviewed, foraminiferal, nannofossil, and quantitative palynological data were available. This paper demonstrates that through the integration of data from all three biostratigraphic disciplines and through taking careful accounts of lithologies, it is possible to make accurate correlations within the Malay Basin, which would not be possible using data from a single discipline. Stratigraphic relationships within upper Oligocene fluvial and lacustrinemore » sediments are best determined from their rich miospore and freshwater algal content. Miospores are also of importance for correlation in the paralic lower Miocene, but in addition, marine flooding surfaces may be characterized by benthic foraminifera, which although not age diagnostic, may permit accurate correlations. These marine pulses sometimes contain age-diagnostic nannofossils, which permit palynological and foraminiferal events to be dated. The lower/middle Miocene boundary is represented by a marine transgressive unit, which can be dated by nannofossils; benthic foraminiferal and palynological events again provide a basis for detailed correlations. The remainder of the middle Miocene, and most of the upper Miocene, consists of paralic sediments for which correlations can be achieved using benthic foraminifera and miospores. Again age-diagnostic nannofossils may be associated with marine flooding surfaces. The upper part of the upper Miocene and the Pliocene-Pleistocene is marine and readily dated using planktonic foraminifera and nannofossils.« less

Effects of Bioadvection by Arenicola marina on Microphytobenthos in Permeable Sediments.

PubMed

Chennu, Arjun; Volkenborn, Nils; de Beer, Dirk; Wethey, David S; Woodin, Sarah A; Polerecky, Lubos

2015-01-01

We used hyperspectral imaging to study short-term effects of bioturbation by lugworms (Arenicola marina) on the surficial biomass of microphytobenthos (MPB) in permeable marine sediments. Within days to weeks after the addition of a lugworm to a homogenized and recomposed sediment, the average surficial MPB biomass and its spatial heterogeneity were, respectively, 150-250% and 280% higher than in sediments without lugworms. The surficial sediment area impacted by a single medium-sized lugworm (~4 g wet weight) over this time-scale was at least 340 cm2. While sediment reworking was the primary cause of the increased spatial heterogeneity, experiments with lugworm-mimics together with modeling showed that bioadvective porewater transport from depth to the sediment surface, as induced by the lugworm ventilating its burrow, was the main cause of the increased surficial MPB biomass. Although direct measurements of nutrient fluxes are lacking, our present data show that enhanced advective supply of nutrients from deeper sediment layers induced by faunal ventilation is an important mechanism that fuels high primary productivity at the surface of permeable sediments even though these systems are generally characterized by low standing stocks of nutrients and organic material.

Effects of Bioadvection by Arenicola marina on Microphytobenthos in Permeable Sediments

PubMed Central

Chennu, Arjun; Volkenborn, Nils; de Beer, Dirk; Wethey, David S.; Woodin, Sarah A.; Polerecky, Lubos

2015-01-01

We used hyperspectral imaging to study short-term effects of bioturbation by lugworms (Arenicola marina) on the surficial biomass of microphytobenthos (MPB) in permeable marine sediments. Within days to weeks after the addition of a lugworm to a homogenized and recomposed sediment, the average surficial MPB biomass and its spatial heterogeneity were, respectively, 150-250% and 280% higher than in sediments without lugworms. The surficial sediment area impacted by a single medium-sized lugworm (~4 g wet weight) over this time-scale was at least 340 cm2. While sediment reworking was the primary cause of the increased spatial heterogeneity, experiments with lugworm-mimics together with modeling showed that bioadvective porewater transport from depth to the sediment surface, as induced by the lugworm ventilating its burrow, was the main cause of the increased surficial MPB biomass. Although direct measurements of nutrient fluxes are lacking, our present data show that enhanced advective supply of nutrients from deeper sediment layers induced by faunal ventilation is an important mechanism that fuels high primary productivity at the surface of permeable sediments even though these systems are generally characterized by low standing stocks of nutrients and organic material. PMID:26230398

Water and sediment dynamics in the Red River mouth and adjacent coastal zone

NASA Astrophysics Data System (ADS)

van Maren, D. S.

2007-02-01

The coastline of the Red River Delta is characterized by alternating patterns of rapid accretion and severe erosion. The main branch of the Red River, the Ba Lat, is presently expanding seaward with a main depositional area several km downstream and offshore the Ba Lat River mouth. Sediment deposition rates are approximately 6 m in the past 50 years. Field measurements were done to determine the processes that regulate marine dispersal and deposition of sediment supplied by the Ba Lat. These measurements reveal that the waters surrounding the Ba Lat delta are strongly stratified with a pronounced southward-flowing surface layer. This southward-flowing surface layer is a coastal current which is generated by river plumes that flow into the coastal zone north of the Ba Lat. However, outflow of turbid river water is not continuous and most sediment enters the coastal zone when the alongshore surface velocities are low. As a consequence, most sediment settles from suspension close to the river mouth. In addition to the southward surface flow, the southward near-bottom currents are also stronger than northward currents. Contrasting with the residual flow near-surface, this southward flow component near-bottom is caused by tidal asymmetry. Because most sediment is supplied by the Ba Lat when wave heights are low, sediment is able to consolidate and therefore the long-term deposition is southward of, but still close to, the Ba Lat mouth.

Distribution and source of organic matter in surface sediment from the muddy deposit along the Zhejiang coast, East China Sea.

PubMed

Xu, Gang; Liu, Jian; Hu, Gang; Jonell, Tara N; Chen, Lilei

2017-10-15

To constrain organic matter compositions and origins, elemental (TOC, TN, C/N) and stable carbon (δ 13 C) and nitrogen isotope (δ 15 N) compositions are measured for surface sediments collected from muddy deposit along the Zhejiang coast, East China Sea. The results showed that the TOC, TN, C/N, δ 13 C, and δ 15 N were 0.19-0.67%, 0.03-0.09%, 6.76-9.22, -23.43 to -20.26‰, and 3.93-5.27‰, respectively. The δ 13 C values showed that the mixing inputs of terrigenous and marine organic matter generally dominated sedimentary organic matter in the west part, and the sedimentary organic matters were mainly influenced by the marine organic matter in the east part of the study area. A stable carbon isotope two end member mixing model estimates ~38% terrestrial -derived and ~62% marine-derived inputs to sedimentary organic matter. Microbial mineralization strongly controls δ 15 N values, and therefore cannot be used to identify the provenance of organic matter for the Zhenjiang coast. Copyright © 2017. Published by Elsevier Ltd.

Marine ferromanganese encrustations: Archives of changing oceans

USGS Publications Warehouse

Koschinsky, Andrea; Hein, James

2017-01-01

Marine iron–manganese oxide coatings occur in many shallow and deep-water areas of the global ocean and can form in three ways: 1) Fe–Mn crusts can precipitate from seawater onto rocks on seamounts; 2) Fe–Mn nodules can form on the sediment surface around a nucleus by diagenetic processes in sediment pore water; 3) encrustations can precipitate from hydrothermal fluids. These oxide coatings have been growing for thousands to tens of millions of years. They represent a vast archive of how oceans have changed, including variations of climate, ocean currents, geological activity, erosion processes on land, and even anthropogenic impact. A growing toolbox of age-dating methods and element and isotopic signatures are being used to exploit these archives.

A Marine Origin for the Meridiani Planum Landing Site?

NASA Technical Reports Server (NTRS)

Parker, T. J.; Haldemann, A. F.

2005-01-01

The Opportunity instruments have provided compelling evidence that the sulfate-rich chemical and siliciclastic sediments at the Meridiani Planum landing site were deposited in shallow water. The local paleo-environment is most often characterized as a broad, shallow sea or large playa, with surface conditions cycling between wet and dry episodes, interbedding evaporates with eolian fine sediments [e.g., 1,2]. This particular working hypothesis is reasonable, considering the area characterized by the rover s mobility. An alternative, marine origin will be considered here, a working hypothesis that we feel provides a better fit to the local-scale results identified by Opportunity, and the regional-scale characteristics of Meridiani Planum provided by data from orbiting spacecraft, when considered together.

Core descriptions, core photographs, physical property logs and surface textural data of sediment cores recovered from the continental shelf of the Monterey Bay National Marine Sanctuary during the research cruises M-1-95-MB, P-2-95-MB, and P-1-97-MB

USGS Publications Warehouse

Orzech, Kevin M.; Dahl, Wendy E.; Edwards, Brian D.

2001-01-01

In response to the 1992 creation of the Monterey Bay National Marine Sanctuary (MBNMS), the United States Geological Survey (USGS) initiated a multiyear investigation of the Sanctuary continental margin. As part of the investigative effort, this report summarizes the shipboard procedures, subsequent laboratory analyses, and data results from three seafloor sampling cruises conducted on the continental shelf between Monterey peninsula, CA and San Francisco, CA. The cruises were conducted in 1995 aboard the NOAA Ship McArthur (M-1-95-MB) and in 1995 and 1997 aboard the R/V Point Sur (P-2-95-MB and P-1-97-MB). Scientists and representatives from the Environmental Protection Agency (EPA), the National Oceanic and Atmospheric Administration (NOAA), the California Department of Fish and Game (CDFG), the University of California Santa Cruz (UCSC), and the San Jose State University Moss Landing Marine Laboratory (SJSU-MLML) supported the research effort. In this report we present sediment descriptions, sediment textural data, physical property logs, station metadata, and photographs of subcores from a total of three hundred and eighty four sample stations. At these sites either a box corer, MultiCore™r, grab sampler or a combination of these sampling devices were used to collect the sea floor sediments. The report is presented in an interactive web-based format with each mapped core station linked to the corresponding description and photo, and to a spreadsheet of surface texture and other sampling data.

Polycyclic aromatic hydrocarbons (PAHs) and alkylated PAHs in the coastal seawater, surface sediment and oyster from Dalian, Northeast China.

PubMed

Hong, Wen-Jun; Jia, Hongliang; Li, Yi-Fan; Sun, Yeqing; Liu, Xianjie; Wang, Luo

2016-06-01

A total of 46 polycyclic aromatic hydrocarbons (PAHs, 21 parent and 25 alkylated) were determined in seawater, surface sediment and oyster from coastal area of Dalian, North China. The concentration of Σ46PAHs in seawater, sediment, and oyster were 136-621 ng/L, 172-4700 ng/g dry weight (dw) and 60.0-129 ng/g wet weight (ww) in winter, and 65.0-1130 ng/L, 71.1-1090 ng/g dw and 72.8-216 ng/g ww in summer, respectively. High PAH levels were found in industrial area both in winter and summer. Selected PAH levels in sediments were compared with Sediments Quality Guidelines (ERM-ERL, TEL-PEL indexes) for evaluation probable toxic effects on marine organism and the results indicate that surface sediment from all sampling sites have a low to medium ecotoxicological risk. Daily intake of PAHs via oyster as seafood by humans were estimated and the results indicated that oyster intake would not pose a health risk to humans even 30 days after a oil spill accident near by. Water-sediment exchange analysis showed that, both in winter and summer, the fluxes for most high molecular weight PAHs were from seawater to sediment, while for low molecular weight PAHs, an equilibrium was reached between seawater and sediment. Copyright © 2016 Elsevier Inc. All rights reserved.

Microbial community composition along a 50 000-year lacustrine sediment sequence

PubMed Central

Ariztegui, Daniel; Horn, Fabian; Kallmeyer, Jens; Orsi, William D

2018-01-01

Abstract For decades, microbial community composition in subseafloor sediments has been the focus of extensive studies. In deep lacustrine sediments, however, the taxonomic composition of microbial communities remains undercharacterized. Greater knowledge on microbial diversity in lacustrine sediments would improve our understanding of how environmental factors, and resulting selective pressures, shape subsurface biospheres in marine and freshwater sediments. Using high-throughput sequencing of 16S rRNA genes across high-resolution climate intervals covering the last 50 000 years in Laguna Potrok Aike, Argentina, we identified changes in microbial populations in response to both past environmental conditions and geochemical changes of the sediment during burial. Microbial communities in Holocene sediments were most diverse, reflecting a layering of taxa linked to electron acceptors availability. In deeper intervals, the data show that salinity, organic matter and the depositional conditions over the Last Glacial-interglacial cycle were all selective pressures in the deep lacustrine assemblage resulting in a genetically distinct biosphere from the surface dominated primarily by Bathyarchaeota and Atribacteria groups. However, similar to marine sediments, some dominant taxa in the shallow subsurface persisted into the subsurface as minor fraction of the community. The subsequent establishment of a deep subsurface community likely results from a combination of paleoenvironmental factors that have shaped the pool of available substrates, together with substrate depletion and/or reworking of organic matter with depth. PMID:29471361

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

PubMed

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

2007-09-30

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

Cable Bacteria and the Bioelectrochemical Snorkel: The Natural and Engineered Facets Playing a Role in Hydrocarbons Degradation in Marine Sediments

PubMed Central

Matturro, Bruna; Cruz Viggi, Carolina; Aulenta, Federico; Rossetti, Simona

2017-01-01

The composition and metabolic traits of the microbial communities acting in an innovative bioelectrochemical system were here investigated. The system, known as Oil Spill Snorkel, was recently developed to stimulate the oxidative biodegradation of petroleum hydrocarbons in anoxic marine sediments. Next Generation Sequencing was used to describe the microbiome of the bulk sediment and of the biofilm growing attached to the surface of the electrode. The analysis revealed that sulfur cycling primarily drives the microbial metabolic activities occurring in the bioelectrochemical system. In the anoxic zone of the contaminated marine sediment, petroleum hydrocarbon degradation occurred under sulfate-reducing conditions and was lead by different families of Desulfobacterales (46% of total OTUs). Remarkably, the occurrence of filamentous Desulfubulbaceae, known to be capable to vehicle electrons deriving from sulfide oxidation to oxygen serving as a spatially distant electron acceptor, was demonstrated. Differently from the sediment, which was mostly colonized by Deltaproteobacteria, the biofilm at the anode hosted, at high extent, members of Alphaproteobacteria (59%) mostly affiliated to Rhodospirillaceae family (33%) and including several known sulfur- and sulfide-oxidizing genera. Overall, we showed the occurrence in the system of a variety of electroactive microorganisms able to sustain the contaminant biodegradation alone or by means of an external conductive support through the establishment of a bioelectrochemical connection between two spatially separated redox zones and the preservation of an efficient sulfur cycling. PMID:28611751

Future direction in marine bacterial agarases for industrial applications.

PubMed

Jahromi, Saeid Tamadoni; Barzkar, Noora

2018-06-16

The marine ecosystem has been known to be a rich source of novel enzymes. Agarase is a key enzyme that can hydrolyze agar in the marine environment. Marine bacterial agarase has been isolated from various sources, such as sediments, coastal water, and deep sea and from the surface of crustaceans and seaweeds. This review presents an account of the agarase production of marine bacteria. General information about agar, agarase, isolation, and purification of marine bacterial agarases; the biochemical properties of native agarase from marine bacteria; the biochemical properties of recombinant marine bacterial agarases from engineered microorganisms; and the industrial future of marine bacterial agarases is analyzed. With recent biotechnological processes, researchers need novel functional enzymes like agarase from marine resources, such as marine bacteria, that can be used for diverse applications in the biotechnological industry. Marine bacterial agarases might be of significant interest to the industry because they are safe and are a natural source. This review highlights the potential of marine bacteria as important sources of agarase for application in various industries.

Dinoflagellate cysts and benthic foraminifera in surface sediments from the Mar Piccolo in Taranto (Ionian Sea, Southern Italy)

NASA Astrophysics Data System (ADS)

Ferraro, L.; Rubino, F.; Frontalini, F.; Belmonte, M.; Di Leo, A.; Giandomenico, S.; Greco, M.; Lirer, F.; Spada, L.; Vallefuoco, M.

2012-12-01

Coastal areas have traditionally been places of human settlement, with the increasing development of cities, industries and other human-related activities possibly having an impact on the aquatic ecosystem. These impacts may take the form of pollution from industrial, domestic, agricultural or mining activities. For this reason, attention to marine environmental problems has recently increased and the search for new methodologies and techniques for the monitoring of coastal-marine areas become more and more active and accurate. In this context biological indicators result a useful tool to provide indication of environmental conditions including the presence or absence of contaminants; in fact biological monitoring is more directly related to the ecological health of an ecosystem than are chemical data. The increasing importance of bioindicators is also encouraged within the European Union's Water Framework Directive (WFD), which aims to achieve a good ecological status in all European water bodies (i.e., rivers, lakes and coastal waters). Among the wide range of bioindicators, 5 biological elements are listed within the WFD: phytoplankton, macroalgae, angiosperms, benthic invertebrates and fishes. Benthic invertebrates as foraminifera represent a group of protozoa widely distributed in all brackish and marine environments which are used in studies assessing the environmental quality of areas subject to intense human activity. Moreover in coastal marine environments benthic and pelagic domain present several relationships, one of these is represented by the life cycles of phytoplankton species, as Dinoflagellates, which include the production of benthic stages (cysts). These dormant stages, which accumulate in confined marine muddy areas, such as ports, lagoons or estuaries, can reach high densities, similar to the seed banks of terrestrial plants. The cysts have a high preservation potential and can rest in/on the sediments for decades. Due to this peculiar characteristic, cysts constitute a reservoir of potential biodiversity but can also be useful indicators of productivity, eutrophication and pollution in recent marine environments. In this way, the sampling sediments of a coastal marine area, allows to monitor the responses of both microplankton and microbenthos to possible disturbance events of the ecosystem. A preliminary study, preparatory to a more detailed sampling survey during winter 2013, was carried out in December 2011 in the Mar Piccolo of Taranto (Ionian Sea), on surface sediment samples which were analyzed to identify living benthic foraminiferal assemblages and dormant stages of plankton in order to establish the potentiality of these organisms as bio-indicators of environmental stress conditions.

Cadmium and zinc isotopes of organic-rich marine sediments during Oceanic Anoxic Event 2

NASA Astrophysics Data System (ADS)

Sweere, T.; Dickson, A. J.; Jenkyns, H. C.; Porcelli, D.; Henderson, G. M.; van den Boorn, S.

2017-12-01

Mesozoic Oceanic Anoxic Events (OAEs) are characterized by widespread deposition of organic-rich sediments and the spread of low-oxygen marine environments. To drive and sustain unusually efficient carbon-burial during these events requires high export productivity rates, which has to be supported by an abundance of nutrients in the surface ocean. The presence of redox-sensitive bio-essential micronutrients may be particularly important, and potentially bio-limiting, during such events as they may be drawn down into sediment under low-oxygen conditions. Cadmium and zinc isotopes have potential as tracers for past (micro)nutrient dynamics considering their nutrient-like distribution in the modern ocean and isotope fractionation with uptake by primary producers. The modern deep ocean is generally well mixed for Cd and Zn while short-term cycling of these elements in the surface ocean imposes regional variation. Additional regional variation may be caused by sulfide formation and associated isotope fractionation in euxinic environments. The impact of such regional environmental conditions on the Cd- and Zn-isotope composition of the sediment therefore needs to be addressed in order to explore the use of these elements as a proxy for past nutrient conditions. Here we present an extensive dataset of cadmium- and zinc-isotope compositions of organic-rich marine sediments from different basins deposited during OAE 2 (Late Cretaceous). This comparison highlights regional differences in Cd- and Zn-isotope compositions. However, despite regional environmental controls, a correlation between δ114Cd and δ66Zn across the different sites is observed, which implies a largely similar control on the two isotope systems. When regional environmental controls are accounted for, the data may provide insight in the δ66Zn and δ114Cd evolution of global seawater during OAE 2 as well as information on the global cycling of redox-sensitive micronutrients during the event

Hydrocarbon gas in sediment of the Southern Pacific Ocean

USGS Publications Warehouse

Kvenvolden, K.A.

1988-01-01

Methane, ethane, ethene, propane, and propene are common hydrocarbon gases in near-surface sediment from offshore areas in the southern Pacific Ocean near Papua New Guinea, the Solomon Islands, Vanuatu, Tonga, New Zealand, and Antarctica. Sea floor sites for sampling of sediment were selected on the basis of anomalies in marine seismic records, and the samples were intentionally biased toward finding possible thermogenic hydrocarbon gases. In none of the areas, however, were thermogenic hydrocarbons clearly identified. The hydrocarbon gases that were found appear to be mainly the products of in situ microbial processes. ?? 1988 Springer-Verlag New York Inc.

Sedimentary features on the surface of Mars as seen from Mariner 6 and 7 photographs

NASA Technical Reports Server (NTRS)

Parsley, R. L.

1973-01-01

Martian sedimentation is primarily aeolian with the principal source areas being the cratered highlands. Lighter albedo in areas of sedimentation may be due to minerals of smaller grain size and/or lighter specific gravity. Martian erosion sedimentation seems to be active as evidenced by removal and/or burial of ejecta mounds and ray ejecta patterns around fresh bowl shaped craters. It is suggested that at least some chaotic terrain may be formed by aeolian removal of material in areas of closely spaced faulting. Transitional areas between uplands and basins are sometimes muted by down slope winds.

Biogeochemistry of Dissolved Free Amino Acids in Marine Sediments.

DTIC Science & Technology

1980-09-01

Oceans , the Black Sea , and the Sea of Azov. Interstitial water of surface sediments | _ A Irom these regions, including even Pacific red clays and...Awapara, 1962; de Zwaan, 1977). Serine has been reported as the major constituent of the ceolomic fluid of a sea urchin (Giordano et al., 1950). The...Harper, and F. P. Filice (1950) The amino acids ot a starfish and a sea urchin (Asteroidea and Echinoidea). Wasmann J. Biol. 8, 129-132. Goldberg, E

Infilling and flooding of the Mekong River incised valley during deglacial sea-level rise

NASA Astrophysics Data System (ADS)

Tjallingii, Rik; Stattegger, Karl; Wetzel, Andreas; Van Phach, Phung

2010-06-01

The abrupt transition from fluvial to marine deposition of incised-valley-fill sediments retrieved from the southeast Vietnamese shelf, accurately records the postglacial transgression after 14 ka before present (BP). Valley-filling sediments consist of fluvial mud, whereas sedimentation after the transgression is characterized by shallow-marine carbonate sands. This change in sediment composition is accurately marked in high-resolution X-ray fluorescence (XRF) core scanning records. Rapid aggradation of fluvial sediments at the river mouth nearly completely filled the Mekong incised valley prior to flooding. However, accumulation rates strongly reduced in the valley after the river-mouth system flooded and stepped back. This also affected the sediment supply to deeper parts of the southeast Vietnamese shelf. Comparison of the Mekong valley-filling with the East Asian sea-level history of sub- and inter-tidal sediment records shows that the transgressive surface preserved in the incised-valley-fill records is a robust sea-level indicator. The valley was nearly completely filled with fluvial sediments between 13.0 and 9.5 ka BP when sea-level rose rather constantly with approximately 10 mm/yr, as indicated by the East Asian sea-level record. At shallower parts of the shelf, significant sediment reworking and the establishment of estuarine conditions at the final stage of infilling complicates accurate dating of the transgressive surface. Nevertheless, incised-valley-fill records and land-based drill sites indicate a vast and rapid flooding of the shelf from the location of the modern Vietnamese coastline to the Cambodian lowlands between 9.5 ka and 8.5 ka BP. Fast flooding of this part of the shelf is related with the low shelf gradient and a strong acceleration of the East Asian sea-level rise from 34 to 9 meter below modern sea level (mbsl) corresponding to the sea-level jump of melt water pulse (MWP) 1C.

Archaeal Diversity Associated with Deep Sea Whalefalls

NASA Astrophysics Data System (ADS)

Wilpiszeski, R.; Goffredi, S.; Turk, K.; Vrijenhoek, R.; House, C. H.; Orphan, V.

2005-12-01

Deep sea whale fall sites support a diverse population of organisms in an otherwise sparsely populated environment. While the macro- and megafauna of these ecosystems have been investigated in some detail, less is known about the nature of associated microbial populations. 16S rRNA gene surveys were used to evaluate the diversity of Archaea in the sediment below one such whale fall at 2800 m water depth and at a nearby control site. A variety of Archaea were identified, including diverse uncultured marine crenarchaeota, phylotypes related to hydrogenotrophic methanogens (Methanogenium spp.), and methylotrophic methanogens associated with the Methanococcoides. No methanogens were discovered at the control site, while hydrogenotrophic methanogens accounted for approximately 20% of the samples from surface sediments below the whale and 35% of the Archaea identified from 12.5 to 15 cm below the whale; the single methylotrophic methanogen was identified within the 12.5 to 15 cm depth sample. The presence of methanogenic phylotypes associated with the whale fall corroborates geochemical observations of elevated methane concentrations observed in the shallow sediments directly beneath the whale fall. This combined geochemical and microbiological evidence suggests that near surface organic matter remineralization is occurring via a methanogenic pathway within this deep sea whale fall habitat rather than the typical sulfidogenic dominated diagenesis commonly observed at other whale fall locations and within shallow marine sediments worldwide.

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

NASA Astrophysics Data System (ADS)

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.

In situ DNA hybridized chain reaction (FISH-HCR) as a better method for quantification of bacteria and archaea within marine sediment

NASA Astrophysics Data System (ADS)

Buongiorno, J.; Lloyd, K. G.; Shumaker, A.; Schippers, A.; Webster, G.; Weightman, A.; Turner, S.

2015-12-01

Nearly 75% of the Earth's surface is covered by marine sediment that is home to an estimated 2.9 x 1029 microbial cells. A substantial impediment to understanding the abundance and distribution of cells within marine sediment is the lack of a consistent and reliable method for their taxon-specific quantification. Catalyzed reporter fluorescent in situ hybridization (CARD-FISH) provides taxon-specific enumeration, but this process requires passing a large enzyme through cell membranes, decreasing its precision relative to general cell counts using a small DNA stain. In 2015, Yamaguchi et al. developed FISH hybridization chain reaction (FISH-HCR) as an in situ whole cell detection method for environmental microorganisms. FISH-HCR amplifies the fluorescent signal, as does CARD-FISH, but it allows for milder cell permeation methods that might prevent yield loss. To compare FISH-HCR to CARD-FISH, we examined bacteria and archaea cell counts within two sediment cores, Lille Belt (~78 meters deep) and Landsort Deep (90 meters deep), which were retrieved from the Baltic Sea Basin during IODP Expedition 347. Preliminary analysis shows that CARD-FISH counts are below the quantification limit for most depths across both cores. By contrast, quantification of cells was possible with FISH-HCR in all examined depths. When quantification with CARD-FISH was above the limit of detection, counts with FISH-HCR were up to 11 fold higher for Bacteria and 3 fold higher for Archaea from the same sediment sample. Further, FISH-HCR counts follow the trends of on board counts nicely, indicating that FISH-HCR may better reflect the cellular abundance within marine sediment than other quantification methods, including qPCR. Using FISH-HCR, we found that archaeal cell counts were on average greater than bacterial cell counts, but within the same order of magnitude.

Single cell genomic study of Dehalococcoidites in deep sea sediments of Peru Margin 1230

NASA Astrophysics Data System (ADS)

Kaster, A.; Meyer-Blackwell, K.; Spormann, A. M.

2013-12-01

Dehalogenating Chloroflexi, such as Dehalococcoidites Dhc were originally discovered as the key microorganisms mediating reductive dehalogenation of the prevalent groundwater contaminants tetrachloroethene and trichloroethene. Molecular and genomic studies on their key enzymes for energy conservation, reductive dehalogenases rdh, have provided evidence for ubiquitous horizontal gene transfer. A pioneering study by Futagami et al. discovered novel putative rdh phylotypes in sediments from the Pacific, revealing an unknown and surprising abundance of rdh genes in pristine habitats. The frequent detection of Dhc-related 16S rRNA genes from these environments implied the occurrence of dissimilatory dehalorespiration in marine subsurface sediments, however, pristine Dhc could never be linked to this activity. Despite being ubiquitous in those environments, metabolic life style or ecological function of Dhc in the absence of anthropogenic contaminants is still completely unknown. We therefore analyzed a non-contaminated deep sea sediment sample of the Peru Margin 1230 site by a single cell genomic (SGC) approach. We present for the first time data on three single Dhc cells, helping to elucidate their role in the poorly understood oligotrophic marine sub-surface environment.

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

PubMed

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.

Tracking the Hercules 265 marine gas well blowout in the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Romero, Isabel C.; Özgökmen, Tamay; Snyder, Susan; Schwing, Patrick; O'Malley, Bryan J.; Beron-Vera, Francisco J.; Olascoaga, Maria J.; Zhu, Ping; Ryan, Edward; Chen, Shuyi S.; Wetzel, Dana L.; Hollander, David; Murawski, Steven A.

2016-01-01

On 23 July 2013, a marine gas rig (Hercules 265) ignited in the northern Gulf of Mexico. The rig burned out of control for 2 days before being extinguished. We conducted a rapid-response sampling campaign near Hercules 265 after the fire to ascertain if sediments and fishes were polluted above earlier baseline levels. A surface drifter study confirmed that surface ocean water flowed to the southeast of the Hercules site, while the atmospheric plume generated by the blowout was in eastward direction. Sediment cores were collected to the SE of the rig at a distance of ˜0.2, 8, and 18 km using a multicorer, and demersal fishes were collected from ˜0.2 to 8 km SE of the rig using a longline (508 hooks). Recently deposited sediments document that only high molecular weight (HMW) polycyclic aromatic hydrocarbon (PAH) concentrations decreased with increasing distance from the rig suggesting higher pyrogenic inputs associated with the blowout. A similar trend was observed in the foraminifera Haynesina germanica, an indicator species of pollution. In red snapper bile, only HMW PAH metabolites increased in 2013 nearly double those from 2012. Both surface sediments and fish bile analyses suggest that, in the aftermath of the blowout, increased concentration of pyrogenically derived hydrocarbons was transported and deposited in the environment. This study further emphasizes the need for an ocean observing system and coordinated rapid-response efforts from an array of scientific disciplines to effectively assess environmental impacts resulting from accidental releases of oil contaminants.

Boundary condition of grounding lines prior to collapse, Larsen-B Ice Shelf, Antarctica.

PubMed

Rebesco, M; Domack, E; Zgur, F; Lavoie, C; Leventer, A; Brachfeld, S; Willmott, V; Halverson, G; Truffer, M; Scambos, T; Smith, J; Pettit, E

2014-09-12

Grounding zones, where ice sheets transition between resting on bedrock to full floatation, help regulate ice flow. Exposure of the sea floor by the 2002 Larsen-B Ice Shelf collapse allowed detailed morphologic mapping and sampling of the embayment sea floor. Marine geophysical data collected in 2006 reveal a large, arcuate, complex grounding zone sediment system at the front of Crane Fjord. Radiocarbon-constrained chronologies from marine sediment cores indicate loss of ice contact with the bed at this site about 12,000 years ago. Previous studies and morphologic mapping of the fjord suggest that the Crane Glacier grounding zone was well within the fjord before 2002 and did not retreat further until after the ice shelf collapse. This implies that the 2002 Larsen-B Ice Shelf collapse likely was a response to surface warming rather than to grounding zone instability, strengthening the idea that surface processes controlled the disintegration of the Larsen Ice Shelf. Copyright © 2014, American Association for the Advancement of Science.

Seasonal variations and sources of sedimentary organic carbon in Tokyo Bay.

PubMed

Kubo, Atsushi; Kanda, Jota

2017-01-30

Total organic carbon (TOC), total nitrogen (TN) contents, their stable C and N isotope ratio (δ 13 C and δ 15 N), and chlorophyll a ([Chl a] sed ) of surface sediments were investigated monthly to identify the seasonal variations and sources of organic matter in Tokyo Bay. The sedimentary TOC (TOC sed ) and TN (TN sed ) contents, and the sedimentary δ 13 C and δ 15 N (δ 13 C sed and δ 15 N sed ) values were higher in summer than other seasons. The seasonal variations were controlled by high primary production in the water column and hypoxic water in the bottom water during summer. The fraction of terrestrial and marine derived organic matter was estimated by Bayesian mixing model using stable isotope data and TOC/TN ratio. Surface sediments in Tokyo Bay are dominated by marine derived organic matter, which accounts for about 69±5% of TOC sed . Copyright © 2016 Elsevier Ltd. All rights reserved.

Unraveling signatures of biogeochemical processes and the depositional setting in the molecular composition of pore water DOM across different marine environments

NASA Astrophysics Data System (ADS)

Schmidt, Frauke; Koch, Boris P.; Goldhammer, Tobias; Elvert, Marcus; Witt, Matthias; Lin, Yu-Shih; Wendt, Jenny; Zabel, Matthias; Heuer, Verena B.; Hinrichs, Kai-Uwe

2017-06-01

Dissolved organic matter (DOM) in marine sediment pore waters derives largely from decomposition of particulate organic matter and its composition is influenced by various biogeochemical and oceanographic processes in yet undetermined ways. Here, we determine the molecular inventory of pore water DOM in marine sediments of contrasting depositional regimes with ultrahigh-resolution mass spectrometry and complementary bulk chemical analyses in order to elucidate the factors that shape DOM composition. Our sample sets from the Mediterranean, Marmara and Black Seas covered different sediment depths, ages and a range of marine environments with different (i) organic matter sources, (ii) balances of organic matter production and preservation, and (iii) geochemical conditions in sediment and water column including anoxic, sulfidic and hypersaline conditions. Pore water DOM had a higher molecular formula richness than overlying water with up to 11,295 vs. 2114 different molecular formulas in the mass range of 299-600 Da and covered a broader range of element ratios (H/C = 0.35-2.19, O/C = 0.03-1.19 vs. H/C = 0.56-2.13, O/C = 0.15-1.14). Formula richness was independent of concentrations of DOC and TOC. Near-surface pore water DOM was more similar to water column DOM than to deep pore water DOM from the same core with respect to formula richness and the molecular composition, suggesting exchange at the sediment-water interface. The DOM composition in the deeper sediments was controlled by organic matter source, selective decomposition of specific DOM fractions and early diagenetic molecule transformations. Compounds in pelagic sediment pore waters were predominantly highly unsaturated and N-bearing formulas, whereas oxygen-rich CHO-formulas and aromatic compounds were more abundant in pore water DOM from terrigenous sediments. The increase of S-bearing molecular formulas in the water column and pore waters of the Black Sea and the Mediterranean Discovery Basin was consistent with elevated HS- concentrations reflecting the incorporation of sulfur into biomolecules during early diagenesis. Sulfurization resulted in an increased average molecular mass of DOM and higher formula richness (up to 5899 formulas per sample). In sediments from the methanogenic zone in the Black Sea, the DOM pool was distinctly more reduced than overlying sediments from the sulfate-reducing zone. Bottom and pore water DOM from the Discovery Basin contained the highest abundances of aliphatic compounds in the entire dataset; a large fraction of abundant N-bearing formulas possibly represented peptide and nucleotide formulas suggesting preservation of these molecules in the life inhibiting environment of the Discovery Basin. Our unique data set provides the basis for a comprehensive understanding of the molecular signatures in pore water DOM and the turnover of sedimentary organic matter in marine sediments.

Spatial distribution and ecological risk assessment of heavy metals in coastal surface sediments in the Hebei Province offshore area, Bohai Sea, China

USGS Publications Warehouse

Ding, Xigui; Ye, Siyuan; Yuan, Hongming; Krauss, Ken W.

2018-01-01

Seven hundred and nine surface sediment samples, along with deeper sediment samples, were collected from Hebei Province along the coastal section of the Bohai Sea, China, and analyzed for grain size, concentrations of organic carbon (Corg) and heavy metals (Cu, Pb, Zn, Cr, Cd, As, and Hg). Results indicated that the average concentrations in the sediments were 16.1 mg/kg (Cu), 19.4 mg/kg (Pb), 50 mg/kg (Zn), 48.8 mg/kg (Cr), 0.1 mg/kg (Cd), 8.4 mg/kg (As), and 20.3 μg/kg (Hg). These concentrations generally met the China Marine Sediment Quality criteria. However, both pollution assessments indicated moderate to strong Cd and Hg contamination in the study area. The potential ecological risk index suggested that the combined ecological risk of the seven studied metals may be low, but that 24.5% of the sites, where sediments were more finer and higher in Corg concentration, had high ecological risk in Hg and Cd pollution.

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in sediments from the Gulf of Batabanó, Cuba.

PubMed

Alonso-Hernandez, C M; Mesa-Albernas, M; Tolosa, I

2014-01-01

The spatial distribution of various organochlorinated compounds, e.g. PCBs, DDTs, HCB and HCHs, were investigated in sediments of the Gulf of Batabanó, Cuba. Among the target organochlorine compounds measured, ΣDDT isomers were the predominant contaminant with concentrations ranging from 0.019 to 1.27 ng g(-1)dry wt. Lindane was present at very low concentrations in the range n.d. to 0.05 ng g(-1), while PCBs and other organochlorine pesticide residues, such as HCB, Heptaclor, Aldrin and Mirex were lower than detection limits (∼0.010 ng g(-1)). According to established sediment quality guidelines, the OCPs concentrations encountered in the surface sediments are probably not having an adverse effect on sediment dwelling organisms. Compared to concentrations reported in coastal environments from other parts of the world, PCBs and OCs concentrations in surface sediments of Batabanó Gulf were low and similar to the reported for remote and pristine environments. These results contribute to the sparse regional database for organochlorinated compounds in the Caribbean marine environment. Copyright © 2013. Published by Elsevier Ltd.

Matrix effects on organic pollutants analysis in marine sediment

NASA Astrophysics Data System (ADS)

Azis, M. Y.; Asia, L.; Piram, A.; Buchari, B.; Doumenq, P.; Setiyanto, H.

2018-05-01

Interference from the matrix sample can influence of the accurate analytical method. Accelerated Solvent Extraction and their purification methods were tried to separate the organic micropollutants respectively in marine sediment. Those matrix were as organic pollutants evaluation in marine environment. Polychlorinated Biphenyls (PCBs) and Organochlorine pesticides (OCPs) are two examples organic pollutant in environment which are carcinogenic and mutagenic. Marine sediments are important matrices of information regarding the human activities in coastal areas as well as the fate and behavior of organic pollutants, which are persistent in long-term. This research purpose to evaluate the matrice effect and the recovery from marine sediment spiking with several standar solution and deuterium of molecular target from organic pollutants in not polluted sample of sediment. Matrice samples was tested from indicate in unpolluted location. The methods were evaluated with standard calibration curve (linearity < 0.999, LOQ various ranged 0.5-1000 pg.μL-1 and LOD > LOQ). Recovery (YE) relative, Matrice Effect (ME) relative correction with deuteriated standar were evaluated the interference the matrix. Interference effect for OCPs compounds were higher than PCBs in marine sediment.

Rare earth elements and neodymium isotopes in sedimentary organic matter

NASA Astrophysics Data System (ADS)

Freslon, Nicolas; Bayon, Germain; Toucanne, Samuel; Bermell, Sylvain; Bollinger, Claire; Chéron, Sandrine; Etoubleau, Joel; Germain, Yoan; Khripounoff, Alexis; Ponzevera, Emmanuel; Rouget, Marie-Laure

2014-09-01

We report rare earth element (REE) and neodymium (Nd) isotope data for the organic fraction of sediments collected from various depositional environments, i.e. rivers (n = 25), estuaries (n = 18), open-ocean settings (n = 15), and cold seeps (n = 12). Sedimentary organic matter (SOM) was extracted using a mixed hydrogen peroxide/nitric acid solution (20%-H2O2-0.02 M-HNO3), after removal of carbonate and oxy-hydroxide phases with dilute hydrochloric acid (0.25 M-HCl). A series of experimental tests indicate that extraction of sedimentary organic compounds using H2O2 may be complicated occasionally by partial dissolution of sulphide minerals and residual carbonates. However, this contamination is expected to be minor for REE because measured concentrations in H2O2 leachates are about two-orders of magnitude higher than in the above mentioned phases. The mean REE concentrations determined in the H2O2 leachates for samples from rivers, estuaries, coastal seas and open-ocean settings yield relatively similar levels, with ΣREE = 109 ± 86 ppm (mean ± s; n = 58). The organic fractions leached from cold seep sediments display even higher concentration levels (285 ± 150 ppm; mean ± s; n = 12). The H2O2 leachates for most sediments exhibit remarkably similar shale-normalized REE patterns, all characterized by a mid-REE enrichment compared to the other REE. This suggests that the distribution of REE in leached sedimentary organic phases is controlled primarily by biogeochemical processes, rather than by the composition of the source from which they derive (e.g. pore, river or sea-water). The Nd isotopic compositions for organic phases leached from river sediments are very similar to those for the corresponding detrital fractions. In contrast, the SOM extracted from marine sediments display εNd values that typically range between the εNd signatures for terrestrial organic matter (inferred from the analysis of the sedimentary detrital fractions) and marine organic matter (inferred from the analysis of local surface seawater). A notable exception is the case of organic matter (OM) fractions leached from cold seep sediment samples, which sometimes exhibit εNd values markedly different from both terrigenous and surface seawater signatures. This suggests that a significant fraction of organic compounds in these sediments may be derived from chemosynthetic processes, recycling pore water REE characterized by a distinct isotopic composition. Overall, our results confirm that organic matter probably plays an important role in the oceanic REE budget, through direct scavenging and remineralization within the water column. Both the high REE abundances and the shape of shale-normalized patterns for leached SOM also suggest that OM degradation in sub-surface marine sediments during early diagenesis could control, to a large extent, the distribution of REE in pore waters. Benthic fluxes of organic-bound REE could hence substantially contribute to the exchange processes between particulates and seawater that take place at ocean margins. Neodymium isotopes could provide useful information for tracing the origin (terrestrial versus marine) and geographical provenance of organic matter, with potential applications in paleoceanography. In particular, future studies should further investigate the potential of Nd isotopes in organic compounds preserved in sedimentary records for reconstructing past variations of surface ocean circulation.

Evaluation of organic geochemical and micropaleontological proxies for Holocene paleoclimate reconstructions in Tampa Bay, Florida

NASA Astrophysics Data System (ADS)

van Soelen, E. E.; Brooks, G.; Lammertsma, E.; Donders, T.; Wagner-Cremer, F.; Sangiorgi, F.; Cremer, H.; Sinninghe Damsté, J. S.; Reichart, G. J.

2009-04-01

The exact consequences of human induced climate change are as yet not known. One of the current debates concerns the relation between rising sea surface temperatures (SST) and enhanced hurricane activity. It has also been suggested that the El Niño Southern Oscillation (ENSO) variability plays a major role in providing favorable circumstances for hurricane development. Paleo-climate reconstructions can help understanding long-term trends in hurricane activity. However, reliable climate reconstructions first require that suitable proxies are developed and tested. For this purpose, a pilot-study was performed using biomarkers, pollen, dinoflagellates and diatoms in a core from Tampa-Bay, Florida, covering the Holocene. The hydrological cycle in this part of Florida is strongly affected by both ENSO [1] and hurricanes. Biomarkers of both terrestrial and marine origin were abundant in the core sediments. High taraxerol concentrations were found which are characteristic for the close proximity of mangrove forests on the bays fringes. Other vascular plant derived biomarkers include friedelanone and β-sitosterol. Marine biomarkers include amongst others dinosterol and long-chain C37 and C38 alkenones, indicative for dinoflagellates and haptophyte algae respectively. These biomarkers are absent in sediments older than 7 kyr BP, indicating a non-marine depositional environment. In sediments younger than 7 kyr BP, increasing amounts of marine biomarkers indicate a transition towards estuarine conditions. SST was reconstructed on the alkenones-based paleothermometer Uk'37 and indicates temperatures of ~ 26°C for the past ~4 kyr. Between 7 and 4 kyr BP, concentrations of alkenones in the sediments are too low for reliable SST reconstructions. The shift towards estuarine conditions is a consequence of rising sea-levels following the last deglaciation and is in agreement with earlier findings by Cronin et al. [2], who recognized a change from lacustrine to marine sediments around 7 kyr BP in the same sediment core. Dinoflagellates and diatoms indicate increasing marine conditions from 7 kyr BP onwards, implying that sea level continued rising. Also the pollen-record shows a shift around 7 kyr BP, with a decrease in Cypress swamp vegetation and a slight increase in mangrove pollen, indicative of transgression. Organic geochemical and micropaleontological proxies are in agreement with each other and confirm earlier findings for Holocene Tampa Bay development. The excellent preservation of both terrestrial and marine biomarkers makes them a useful proxy for the reconstruction of SST, precipitation and runoff and eventually hurricanes, especially when read a multi-proxy approach.

Southern Hemisphere anticyclonic circulation drives oceanic and climatic conditions in late Holocene southernmost Africa

NASA Astrophysics Data System (ADS)

Hahn, Annette; Schefuß, Enno; Andò, Sergio; Cawthra, Hayley C.; Frenzel, Peter; Kugel, Martin; Meschner, Stephanie; Mollenhauer, Gesine; Zabel, Matthias

2017-06-01

Due to the high sensitivity of southern Africa to climate change, a reliable understanding of its hydrological system is crucial. Recent studies of the regional climatic system have revealed a highly complex interplay of forcing factors on precipitation regimes. This includes the influence of the tropical easterlies, the strength of the southern hemispheric westerlies as well as sea surface temperatures along the coast of the subcontinent. However, very few marine records have been available in order to study the coupling of marine and atmospheric circulation systems. Here we present results from a marine sediment core, recovered in shallow waters off the Gouritz River mouth on the south coast of South Africa. Core GeoB18308-1 allows a closer view of the last ˜ 4 kyr. Climate sensitive organic proxies, like the distribution and isotopic composition of plant-wax lipids as well as indicators for sea surface temperatures and soil input, give information on oceanographic and hydrologic changes during the recorded time period. Moreover, the micropaleontology, mineralogical and elemental composition of the sediments reflect the variability of the terrigenous input to the core site. The combination of down-core sediment signatures and a catchment-wide provenance study indicate that the Little Ice Age ( ˜ 300-650 cal yr BP) was characterized by climatic conditions favorable to torrential flood events. The Medieval Climate Anomaly ( ˜ 950-650 cal yr BP) is expressed by lower sea surface temperatures in the Mossel Bay area and humid conditions in the Gouritz River catchment. These new results suggest that the coincidence of humid conditions and cooler sea surface temperatures along the south coast of South Africa resulted from a strengthened and more southerly anticyclonic circulation. Most probably, the transport of moisture from the Indian Ocean by strong subtropical easterlies was coupled with Agulhas Bank upwelling pulses, which were initiated by an increase in Agulhas Current strength.

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

PubMed Central

Tenzer, R.; Gladkikh, V.

2014-01-01

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

Direct visualization of clay microfabric signatures driving organic matter preservation in fine-grained sediment

NASA Astrophysics Data System (ADS)

Curry, Kenneth J.; Bennett, Richard H.; Mayer, Lawrence M.; Curry, Ann; Abril, Maritza; Biesiot, Patricia M.; Hulbert, Matthew H.

2007-04-01

We employed direct visualization of organic matter (OM) sequestered by microfabric signatures in organo-clay systems to study mechanisms of OM protection. We studied polysaccharides, an abundant class of OM in marine sediments, associated with the nano- and microfabric of clay sediment using a novel application of transmission electron microscopy, histochemical staining (periodic acid-thiosemicarbazide-silver proteinate), and enzymatic digestion techniques. We used two experimental organo-clay sediment environments. First, laboratory-consolidated sediment with 10% chitin (w/w) added was probed for chitin before and after digestion with chitinase. Second, fecal pellets from the polychaete Heteromastus filiformis were used as a natural environment rich in clay and polysaccharides. Sections of this material were probed with silver proteinate for polysaccharides before and after digestion with a mixture of enzymes (amylase, cellulase, chitinase, dextranase, and pectinase). In both environments, chitin or other polysaccharides were found within pores, bridging clay domains, and attached to clay surfaces in undigested samples. Digested samples showed chitin or polysaccharides more closely associated with clay surfaces and in small pores. Our results imply protective roles for both sorption to clay surfaces and encapsulation within clay microfabric signatures.

DISSOLVED-COLLOIDAL PARTITIONING OF MOBILIZED METALS DURING RESUSPENSION OF MARINE SEDIMENTS

EPA Science Inventory

Sediments in many urban estuaries are contaminated by potentially toxic heavy metals. Over time, many of these metals accumulate in the sediment due to physico-chemical processes which remove them from the water column. Marine sediments are regularly subjected to physical process...

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

PubMed

Yost, Sally L; Pennington, Judith C; Brannon, James M; Hayes, Charolett A

2007-08-01

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

Organic matter in sediments of an acidic mining lake as assessed by lipid analysis. Part I: fatty acids.

PubMed

Poerschmann, Juergen; Koschorreck, Matthias; Górecki, Tadeusz

2012-01-01

Fatty acid (FA) patterns of sediments collected from the bottom of an acidic mine pit lake (AML) at different depths (surface sediment: 0 to 1cm; deep sediment: 4 to 5 cm) were studied to characterize microbial communities and the sources of sedimentary organic matter (SOM). Studies were performed on the molecular level utilizing source-specific, diagnostic FA biomarkers. The biomarker-based approach has been used widely in marine sediment studies, but has not been applied for sediments from AMLs so far. Combined FA concentrations in the surface sediment were higher compared to those in the deep sediment (497 vs. 127 μg g(-1)d.w., respectively). This was related to deposition of autochthonous biomass and higher terrestrial plants onto the surface sediment, as well as--to lesser extent--with higher bacterial activity on the sediment-water interface. The FA distribution in both sediments was characterized by a strong even-over-odd preference and was bimodal in nature: there was a cluster at nC(14)-nC(18) characteristic of chiefly autochthonous (algal and bacterial) SOM production, and another cluster at nC(22-28) related to input from higher plants. The FA distribution in the surface sediment pointed to higher terrestrial input compared to autochthonous contribution to SOM (67%:33%) as an estimate. Fingerprinting of viable bacteria was accomplished through signature FA markers including branched C(15) and C(17) surrogates, cyclopropanoic acids, 3-hydroxy (OH) acids and monounsaturated surrogates with unusual double bond localization. The abundance of Gram-negative bacteria was higher in the surface sediment as evidenced by total diagnostic 3-OH-fatty acids (37 μg g(-1) versus 25 μg g(-1)). Potential source taxa in both sediment layers included acidophilic iron- and sulfur-oxidizing bacteria including Acidithiobacillus ferrooxidans. High abundances of terminally branched C(15) and C(17) surrogates in both sediments pointed to sulfate- and iron-reducing bacteria. Signature FAs characteristic of methanotrophs were virtually lacking in both sediments. Copyright © 2011 Elsevier B.V. All rights reserved.

Evaluation of the levels of alcohol sulfates and ethoxysulfates in marine sediments near wastewater discharge points along the coast of Tenerife Island.

PubMed

Fernández-Ramos, C; Ballesteros, O; Zafra-Gómez, A; Camino-Sánchez, F J; Blanc, R; Navalón, A; Pérez-Trujillo, J P; Vílchez, J L

2014-02-15

Alcohol sulfates (AS) and alcohol ethoxysulfates (AES) are all High Production Volume and 'down-the-drain' chemicals used globally in detergent and personal care products, resulting in low levels ultimately released to the environment via wastewater treatment plant effluents. They have a strong affinity for sorption to sediments. Almost 50% of Tenerife Island surface area is environmentally protected. Therefore, determination of concentration levels of AS/AES in marine sediments near wastewater discharge points along the coast of the Island is of interest. These data were obtained after pressurized liquid extraction and liquid chromatography-tandem mass spectrometry analysis. Short chains of AES and especially of AS dominated the homologue distribution for AES. The Principal Components Analysis was used. The results showed that the sources of AS and AES were the same and that both compounds exhibit similar behavior. Three different patterns in the distribution for homologues and ethoxymers were found. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

PubMed

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.

Spatial distribution and contamination assessment of heavy metals in marine sediments of the southern coast of Sfax, Gabes Gulf, Tunisia.

PubMed

Naifar, Ikram; Pereira, Fernando; Zmemla, Raja; Bouaziz, Moncef; Elleuch, Boubaker; Garcia, Daniel

2018-06-01

In order to investigate the current distribution of metal concentrations in surface marine sediments of the southern coast of Sfax (Tunisia), thirty-nine samples were collected in the vicinity of a mixed industrial and domestic wastewater effluent discharge. In comparison with the threshold effect level and probable effect level, the majority of metals had high ecological and biological risks. Enrichment factor and geoaccumulation Index showed that the majority of sediments are unpolluted by As, Ni and Pb, moderately polluted by Cr and Cu and moderately to strongly polluted by P, Y, Zn. Besides, all sites are extremely polluted by Cd. Principal component analysis indicates that As, Cu and Ni were mainly from lithogenic sources, whereas Cd, Cr, F, P, Pb, Y and Zn were mainly derived from anthropogenic source. Findings of this research can be used as suitable reference for future studies and environmental management plans in the region. Copyright © 2018 Elsevier Ltd. All rights reserved.

Baseline study on trace and rare earth elements in marine sediments collected along the Namibian coast.

PubMed

Orani, Anna Maria; Vassileva, Emilia; Wysocka, Irena; Angelidis, Michael; Rozmaric, Martina; Louw, Deon

2018-06-01

Namibia is a fast-growing country with extensive mineral extraction activities used in diamond, fluorspar, uranium, and metals production. To assess the impact of land based human activities on the Namibian coastal marine environment, 25 elements were analyzed in 22 surface sediments samples collected along the coast. After applying a variety of pollution assessment indices (Enrichment Factor, Igeo and Pollution Load Indexes) was concluded that As, Cd and Sb were considerably enriched in the sediments from several sites, while Cu, Pb and Zn showed very high enrichment near the Walvis Bay harbor. Pearson's correlation and Principal Component Analysis were used to investigate common metal sources. Additionally, the determination of Pb isotope ratios confirmed the contribution of land based human activities at Walvis Bay and Lüderitz as sources of pollution. The analysis of REEs did not reveal any important enrichment due to anthropogenic activities, but provides a needed baseline for further investigations. Copyright © 2018 Elsevier Ltd. All rights reserved.

Abundance and Co-Distribution of Widespread Marine Archaeal Lineages in Surface Sediments of Freshwater Water Bodies across the Iberian Peninsula.

PubMed

Compte-Port, Sergi; Subirats, Jèssica; Fillol, Mireia; Sànchez-Melsió, Alexandre; Marcé, Rafael; Rivas-Ruiz, Pedro; Rosell-Melé, Antoni; Borrego, Carles M

2017-11-01

Archaea inhabiting marine and freshwater sediments have a relevant role in organic carbon mineralization, affecting carbon fluxes at a global scale. Despite current evidences suggesting that freshwater sediments largely contribute to this process, few large-scale surveys have been addressed to uncover archaeal diversity and abundance in freshwater sedimentary habitats. In this work, we quantified and high-throughput sequenced the archaeal 16S rRNA gene from surficial sediments collected in 21 inland waterbodies across the Iberian Peninsula differing in typology and trophic status. Whereas methanogenic groups were dominant in most of the studied systems, especially in organic-rich sediments, archaea affiliated to widespread marine lineages (the Bathyarchaeota and the Thermoplasmata) were also ubiquitous and particularly abundant in euxinic sediments. In these systems, Bathyarchaeota communities were dominated by subgroups Bathyarchaeota-6 (87.95 ± 12.71%) and Bathyarchaeota-15 (8.17 ± 9.2%) whereas communities of Thermoplasmata were mainly composed of members of the order Thermoplasmatales. Our results also indicate that Archaea accounted for a minor fraction of sedimentary prokaryotes despite remarkable exceptions in reservoirs and some stratified lakes. Copy numbers of archaeal and bathyarchaeotal 16S rRNA genes were significantly different when compared according to system type (i.e., lakes, ponds, and reservoirs), but no differences were obtained when compared according to their trophic status (from oligotrophy to eutrophy). Interestingly, we obtained significant correlations between the abundance of reads (Spearman r = 0.5, p = 0.021) and OTU richness (Spearman r = 0.677, p < 0.001) of Bathyarchaeota and Thermoplasmata across systems, reinforcing the hypothesis of a potential syntrophic interaction between members of both lineages.

Historical trace element accumulation in marine sediments from the Tamaulipas shelf, Gulf of Mexico: An assessment of natural vs anthropogenic inputs.

PubMed

Celis-Hernandez, Omar; Rosales-Hoz, Leticia; Cundy, Andrew B; Carranza-Edwards, Arturo; Croudace, Ian W; Hernandez-Hernandez, Hector

2018-05-01

The Gulf of Mexico is considered one of the world's major marine ecosystems, supporting important fisheries and habitats such as barrier islands, mangrove forests, seagrass beds, coral reefs etc. It also hosts a range of complex offshore petroleum exploration, extraction, and refining industries, which may have chronic or acute impacts on ecosystem functioning. Previous work on the marine effects of this activity is geographically incomplete, and has tended to focus on direct hydrocarbon impacts, while impacts from other related contaminants (e.g. heavy metals, salt-rich drilling muds) which may be discharged from oil facilities have not been widely assessed. Here, we examine historical trace element accumulation in marine sediments collected from four sites in the Tamaulipas shelf, Gulf of Mexico, in the area of the Arenque oil field. Dated sediment cores were used to examine the sources, and historical and contemporary inputs, of trace metals (including those typically present in oil industry discharges) and their potential biological impact in the Tamaulipas aquatic environment over the last 100years. CaO (i.e. biogenic component) normalized data showed increasing V, Cr, Zn, Cu, Pb, Zr and Ba towards the sediment surface in three of the four cores, with Ba and V (based on an adverse effect index) possibly associated with adverse effects on organisms. Dated Ba/CaO profiles show an increase of 30-137% after opening of oil installations in the study area, and can be broadly correlated with increasing oil industry activities across the wider Gulf of Mexico. Data do not record however a clear enhancement of Ba concentration in sediment cores collected near to oil platforms over more distal cores, indicating that any Ba released from drilling platforms is incorporated quickly into the sediments around the drilling sites, and once this element has been deposited its rate of resuspension and mobility is low. Sediment core data from the Tamaulipas shelf show the influence of oil industry activities on selected trace element concentrations, with Ba/CaO broadly correlating with increasing oil industry activities across the wider Gulf of Mexico. Copyright © 2017 Elsevier B.V. All rights reserved.

Marine historical ecology at the Brijuni Islands, Croatia: preliminary results from down-core changes of foraminiferal assemblages

NASA Astrophysics Data System (ADS)

Vidovic, Jelena; Cosovic, Vlasta; Gallmetzer, Ivo; Haselmair, Alexandra; Zuschin, Martin

2015-04-01

The Late Holocene in the northern Adriatic is characterized by the eustatic peak of the sea-level rise, followed by the equilibrium between the regional tectonic subsidence and hydro-isostatic emergence and relatively stable sea level for a few thousand years. During this period the area experienced changes in sedimentation rate, food/oxygen availability in the benthic ecosystem and eutrophication with seasonal hypoxic and anoxic events. In order to reconstruct the marine paleoecology in the Brijuni Islands area during this period, a multidisciplinary study was carried out, including geochemical (TOC, trace metals, carbonate content), micropaleontological analyses (benthic foraminifera) and dating of sediments and mollusc shells. The principal aim of this study is to observe the effects of ecological shifts on foraminiferal assemblages during the Late Holocene. One core of 1.5 m length was taken at a sampling station south of Veli Brijuni Island, located within a marine protected area with no fishing/dredging pressure (Croatian national park). The core was sliced into smaller subsamples, and four sediment fractions of each subsample (63, 125, 250 and 500 µm) were analyzed for standard properties of the foraminiferal community (species richness, faunal composition, biodiversity indices), in comparison with relevant physical and geochemical properties of the sediment. The results concerning changes in foraminiferal species composition and abundance point to differences within the core: surface sediments are dominated by suspension feeders (Planorbulina mediterranensis, Lobatula lobatula, Cibicides variabilis, Cibicides refulgens), whereas deposit feeders (genera Textularia, Siphonaperta, Adelosina, Trioculina) appear in higher abundances at approximately 30 cm of the sediment depth and dominate down-core. Species richness in the first 30 cm is lower (10 to 34 species per sample) in comparison to the middle part of the core (39 to 53 species), and decreases again at 100 cm to 25 to 42 species per sample. Diversity indices follow the pattern of species richness and point to normal marine conditions. Similarity indices rise with core depth. The radiometric dating of the sediments together with carbon-calibrated amino acid- racemisation of mollusc shells from selected species will help to determine the timing of major ecological changes.

Flavins in Marine Sediments: A Potentially Ubiquitous Intermediary In Microbial Electron Transfer

NASA Astrophysics Data System (ADS)

Monteverde, D.; Sylvan, J. B.; Suffridge, C.; Berelson, W.; Sanudo-Wilhelmy, S. A.; Baronas, J. J.

2016-12-01

The flavins (riboflavin, flavin mononucleotide [FMN], flavin adenine dinucleotide [FA­­D]) are a class of organic compounds synthesized by organisms to assist in redox reactions. They represent the largest class of required coenzymes, rivaled only by iron in the number of unique enzymes they bind. In addition to internal use, cultured metal-reducing organisms such as Shewanella and Geobacter have been known to release flavins into the extracellular pool to aid in external electron transfer. So called "electron shuttles" can allow organisms to overcome unfavorable geochemical zonation by transferring electrons onto a relatively distant insoluble acceptor. Despite the extensive culture work, flavins have not been systematically measured in the environment. Here we present the first set of flavin profiles from the water column and pore waters of a marine environment. Samples were taken from San Pedro Basin, a 900 meter deep, silled basin, with high seasonal inputs of organic carbon, low bottom water oxygen concentrations, and laminated sediments - making it ideal to explore variations in sediment geochemical zonations. Dissolved flavin concentrations in the water column and pore waters collected from two cores were preconcentrated via solid phase extraction and measured via LC/MS. Flavin profiles are compared to a suite of geochemical parameters as well as sediment microbial 16s rRNA data. Preliminary results show that FMN is typically an order of magnitude higher concentration than riboflavin (800-300pM versus 100-50pM). Porewater concentrations were elevated over water column values for all analytes (ranging from 100-2000pM) and displayed an increasing trend with depth in both cores. This increasing trend correlated with a decrease in dissolved Fe (ranging from 160 µM in surface sediments to 65 µM at 40 cm) and shifts in microbial diversity from sediments shallower than 5 cm depth dominated by Delta- and Gammaproteobacteria to subsurface sediments dominated by Chloroflexi and Archaea at 20-40 cm. These first environmental profiles of flavins in the marine environmental support previous observations of the importance of electron transfer intermediaries in culture and point to an important role for flavins in modern marine microbial communities.

Sediment Resuspension by Ship Traffic in Newark Bay, New Jersey

DTIC Science & Technology

2015-04-01

increased turbidity and sediment deposition on corals (Bermuda). Bulletin of Marine Science 87(3):659- 679. Kelderman, P., D. B . Kassie, M . Bijlsma, L. C...in the coastal marine environment. Marine Ecology Progress Series 315:13-18. Maa, J. P.-Y., and B . Chadwick . 2007. Estimation of annual average... B . Ward, B . Boyd, W. Murphy.R. Nolen-Hoeksema, M . Art, and D. A. Rosales. 2011a. Sediment, sedimentation, and environments of the lower Hackensack

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

NASA Astrophysics Data System (ADS)

Ogrinc, N.; Faganeli, J.

2006-05-01

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

Remediation of metal-contaminated marine sediments using active capping with limestone, steel slag, and activated carbon: a laboratory experiment.

PubMed

Park, Seong-Jik; Kang, Ku; Lee, Chang-Gu; Choi, Jae-Woo

2018-05-18

The objectives of this study are to assess the effectiveness of limestone (LS), steel slag (SS), and activated carbon (AC) as capping materials to sequester trace metals including As, Cd, Cr, Cu, Ni, Pb, and Zn in heavily contaminated marine sediments and to minimize the release of these metals into the water column. A flat flow tank was filled with 10 mm of capping material, contaminated sediments, and seawater, and the metal concentrations were monitored over 32 d. After completion of the flow tank experiments, the sediments below the capping material were sampled and were sequentially extracted. SS effectively reduced the As, Cr, Cu, Ni, Pb, and particularly Cd elution from the contaminated sediments to the overlying seawater. Adsorption and surface precipitation were the key mechanisms for interrupting the release of cationic trace metals by SS. LS was appropriate for interrupting the release of only Cu and Pb with high hydrolysis reaction constants. AC capping could interrupt the release of Cr, Cu, Ni, and particularly Zn from the sediments by binding with the metals via electrostatic interaction. The results obtained from the sequential extraction revealed that LS capping is appropriate for stabilizing Zn, whereas AC is appropriate for Cd and Pb. LS, SS, and AC can be applied effectively for remediation of sediments contaminated by trace metals because it interrupts their release and stabilizes the trace metals in the sediments.

Combining contamination indexes, sediment quality guidelines and multivariate data analysis for metal pollution assessment in marine sediments of Cienfuegos Bay, Cuba.

PubMed

Peña-Icart, Mirella; Pereira-Filho, Edenir Rodrigues; Lopes Fialho, Lucimar; Nóbrega, Joaquim A; Alonso-Hernández, Carlos; Bolaños-Alvarez, Yoelvis; Pomares-Alfonso, Mario S

2017-02-01

The purpose of the present work was to combine several tools for assessing metal pollution in marine sediments from Cienfuegos Bay. Fourteen surface sediments collected in 2013 were evaluated. Concentrations of As, Cu, Ni, Zn and V decreased respect to those previous reported. The metal contamination was spatially distributed in the north and south parts of the bay. According to the contamination factor (CF) enrichment factor (EF) and index of geoaccumulation (I geo ), Cd and Cu were classified in that order as the most contaminated elements in most sediment. Comparison of the total metal concentrations with the threshold (TELs) and probable (PELs) effect levels in sediment quality guidelines suggested a more worrisome situation for Cu, of which concentrations were occasional associated with adverse biological effects in thirteen sediments, followed by Ni in nine sediments; while adverse effects were rarely associated with Cd. Probably, Cu could be considered as the most dangerous in the whole bay because it was classified in the high contamination levels by all indexes and, simultaneously, associated to occasional adverse effects in most samples. Despite the bioavailability was partially evaluated with the HCl method, the low extraction of Ni (<3% in all samples) and Cu (<55%, except sample 3) and the relative high extraction of Cd (50% or more, except sample 14) could be considered as an attenuating (Ni and Cu) or increasing (Cd) factor in the risk assessment of those element. Copyright © 2016. Published by Elsevier Ltd.

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

PubMed Central

Durbin, Alan M.; Teske, Andreas

2012-01-01

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

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

EPA Science Inventory

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

Removal rates of dissolved munitions compounds in seawater.

PubMed

Smith, Richard W; Vlahos, Penny; Tobias, Craig; Ballentine, Mark; Ariyarathna, Thivanka; Cooper, Christopher

2013-08-01

The historical exposure of coastal marine systems to munitions compounds is of significant concern due to the global distribution of impacted sites and known toxicological effects of nitroaromatics. In order to identify specific coastal regions where persistence of these chemicals should be of concern, it is necessary to experimentally observe their behavior under a variety of realistic oceanographic conditions. Here, we conduct a mesocosm scale pulse addition experiment to document the behavior of two commonly used explosives, 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in simulated marine systems containing water and sediments collected from Long Island Sound, CT. The addition of sediments and sediment grain-size had a major influence on the loss rates of all compounds detected. RDX and reduced TNT products were removed from seawater only in the presence of sediment, and TNT degraded significantly faster in the presence of sediment. Both compounds were removed from the system faster with decreasing grain-size. Based on these findings and a thorough review of the literature, we hypothesize that in addition to bacterial abundance and nutrient availability, TNT removal rates in coastal marine waters may be controlled by sorption and rapid surface-mediated bacterial transformation, while RDX removal rates are controlled by diffusion into sedimentary anoxic regions and subsequent anaerobic bacterial breakdown. A comparison of published removal rates of RDX and TNT highlights the extreme variability in measured degradation rates and identifies physicochemical variables that covary with the breakdown of these munitions compounds. Copyright © 2013 Elsevier Ltd. All rights reserved.

Temperature dependency of long-chain alkenone distributions in recent to fossil limnic sediments and in lake waters 1

NASA Astrophysics Data System (ADS)

Zink, Klaus-G.; Leythaeuser, Detlev; Melkonian, Michael; Schwark, Lorenz

2001-01-01

Distribution patterns of C 37 and C 38 polyunsaturated long-chain alkenones (LCAs) serve as proxies for the determination of paleotemperatures for marine surface waters. We studied Recent/Subrecent and Late Glacial/Holocene sediments from Germany, Austria, Russia, and the U.S. to test for a correspondence between LCA distribution and surface water temperature in limnic systems. Previously, reports of LCA occurrence were restricted to sediments of 6 wide distributed freshwater and alkaline lakes. In this study 13 of 27 investigated lakes contained LCAs in surface sediments with concentrations varying between 12 to 205 μg/g TOC. Late Glacial to Holocene sediment sequences from Lake Steisslingen and Lake Wummsee, (Germany), Lake Pichozero (Russia), and Brush Lake (U.S.A.) contained abundant LCAs with averaged concentrations of 33 to 7536 μg/g TOC. For the first time we observed the occurrence of LCAs within in the water column of oligotrophic Lake Stechlin (NE-Germany). Alkenones were restricted to the zone of maximum chlorophyll concentration within the water column indicating that LCAs have a biosynthetic origin and can be attributed to phototrophic (micro)algae. Attempts to identify the producing organism, however, were not successful. Culture experiments allow various phytoplankton to be excluded as producers. Alkenone-producing algae are evidently of small size, hindering microscopical identification. LCAs commonly occur in high concentrations in Late Glacial sediments, mainly during the cold period of the Younger Dryas, whereas the Holocene usually is devoid of polyunsaturated alkenones. The episodic occurrence of LCAs restricts their utility as proxies for continuous geological records. Furthermore, lack of microscopical verification and the episodic distribution allow for different producers of unsaturated alkenones in Recent and Late Glacial sediments. An empirical relationship between LCA distribution and temperature was observed. In fossil sediments from Lake Steisslingen, there is a good correspondence between Uk37 and the temperature-controlled δ 18O isotope ratio of lake chalk. Comparison of LCA patterns obtained from the uppermost centimetres of lake sediments with averaged summer surface water temperatures of the lakes studied, demonstrates a trend of covariance ( r2: Uk'37 = 0.90, Uk37 = 0.67; n = 9). Hence, the same mechanism that causes temperature-dependence of LCA patterns in marine systems might be effective in limnic settings. Identification of alkenone producers and their culture under controlled temperature are still mandatory before LCAs can be routinely applied as paleotemperature proxy in limnic systems.

Terrestrial plant biopolymers in marine sediments

NASA Astrophysics Data System (ADS)

Gough, Mark A.; Fauzi, R.; Mantoura, C.; Preston, Martin

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 characterised 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 lignin/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 ( ca. 0.5 μgg-1 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. To account for these observations, preferential offshore transport of finer and more degraded material is proposed. Nonspecific oxidation products dominated the gas chromatograms of NEA sediments, which appear to originate from marine sources of sedimentary organic carbon. 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 recognisable land plant biopolymers occurs in shelf seas.

Development and Evaluation of Reverse Polyethylene Samplers for Marine Phase II Whole-Sediment Toxicity Identification Evaluation

EPA Science Inventory

Marine and estuarine sediments accumulate contaminants and act as a sink for a wide range of toxic chemicals. As a result, the sediments themselves can become a source of contamination. At sufficient levels, contaminated sediments can cause benthic impairments and toxicity to mar...

Relationship between sediment morphology and oil pollution along the Suez Canal beaches, Egypt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barakat, M.A.K.; Shimy, T.M.; Mostafa, Y.M.

1996-10-01

In this study, marine surface sediments are collected from nine locations along the Suez Canal in order to investigate the relationship between the morphology of sands in the studied beaches and pollution by oil. Basically, the studied samples were analyzed by three techniques: grains-size analysis, microscopic examination, and gas chromatographic (GC) analysis. This study concluded that medium sand is the major class represented in the studied marine sediments. Pollution in these sand grains increases in the irregular grains more so than in the more rounded grains. Also, deep surface points, pitting, and fissures are considered to be good sites tomore » precipitate oil contamination. Also, the presence of iron oxides may be taken as evidence for tanker ballast washings. The heavy fraction (zircon) shows more contamination than the light fraction (quartz) in these samples. Finally, GC profiles have shown two types of samples: one typical of weathered or highly weathered crude oil patterns and the other for samples with very highly weathered profiles. The relationship obtained between morphology studies and both oil content and GC chromatogram profiles indicates that all of the studied locations are suffering from pollution of oil that is spilled while shipping petroleum through the Suez Canal.« less

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

NASA Astrophysics Data System (ADS)

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.

Mass extinctions, atmospheric sulphur and climatic warming at the K/T boundary

NASA Technical Reports Server (NTRS)

Rampino, Michael R.; Volk, Tyler

1988-01-01

The possible climatic effects of a drastic decrease in cloud condensation nuclei (CCN) associated with a severe reduction in the global marine phytoplankton abundance are investigated. Calculations suggest that a reduction in CCN of more than 80 percent and the resulting decrease in marine cloud albedo could have produced a rapid global warming of 6 C or more. Oxygen isotope analyses of marine sediments from many parts of the world have been interpreted as indicating a marked warming coincident with the demise of calcareous nannoplankton at the K/T boundary. Decreased marine cloud albedo and resulting high sea surface temperatures could have been a factor in the maintenance of low productivity in the 'Strangelove Ocean' period following the K/T extinctions.

Extraction of organic contaminants from marine sediments and tissues using microwave energy.

PubMed

Jayaraman, S; Pruell, R J; McKinney, R

2001-07-01

In this study, we compared microwave solvent extraction (MSE) to conventional methods for extracting organic contaminants from marine sediments and tissues with high and varying moisture content. The organic contaminants measured were polychlorinated biphenyl (PCB) congeners, chlorinated pesticides, and polycyclic aromatic hydrocarbons (PAHs). Initial experiments were conducted on dry standard reference materials (SRMs) and field collected marine sediments. Moisture content in samples greatly influenced the recovery of the analytes of interest. When wet sediments were included in a sample batch, low recoveries were often encountered in other samples in the batch, including the dry SRM. Experiments were conducted to test the effect of standardizing the moisture content in all samples in a batch prior to extraction. SRM1941a (marine sediment). SRM1974a (mussel tissue), as well as QA96SED6 (marine sediment), and QA96TIS7 (marine tissue), both from 1996 NIST Intercalibration Exercise were extracted using microwave and conventional methods. Moisture levels were adjusted in SRMs to match those of marine sediment and tissue samples before microwave extraction. The results demonstrated that it is crucial to standardize the moisture content in all samples, including dry reference material to ensure good recovery of organic contaminants. MSE yielded equivalent or superior recoveries compared to conventional methods for the majority of the compounds evaluated. The advantages of MSE over conventional methods are reduced solvent usage, higher sample throughput and the elimination of halogenated solvent usage.

Effect of abalone farming on sediment geochemistry in the Shallow Sea near Wando, South Korea

NASA Astrophysics Data System (ADS)

Kang, Jeongwon; Lee, Yeon Gyu; Jeong, Da Un; Lee, Jung Sick; Choi, Yang Ho; Shin, Yun Kyung

2015-12-01

Wando County has grown up to 93% of the total abalone produced in South Korea since the late 1990s; however, this production has been decreasing in recent years. The objectives of this study were to understand the potential contamination risks of abalone farming and to examine the influence of intensive abalone farming on sediment quality by analyzing grain-size composition, organic matter (total organic carbon (TOC), total nitrogen (TN), total sulfur (TS)) and heavy metal content, pH, and 210Pb geochronology. The results of organic matter analysis from surface and core sediment (length: 64 cm) showed that the area around the abalone farm had oxic marine-to-brackish conditions, but that the area directly below an abalone cage (location 7) had reductive conditions, with a C/S ratio of ~2. The average TN levels in the surface and core sediments were 0.25% and 0.29%, respectively, and this was predominantly due to the use of seaweed for feed. The low sediment pH (surface, 7.23; core, 7.04), indicates that acidification of the bottom sediment has gradually increased since the initiation of abalone farming and is likely due to the continuous accumulation of uneaten feed and feces. Heavy metal pollution was not apparent based on the examination of EF and Igeo, although the excess metal flux of Ni, Pb, Cu, Co, As, and Cd increased toward surface of the sediment core. These sediment changes may be caused by the rapid accumulation (sedimentation rate: 1.45 cm/year) of sludge discharged from the abalone farm and may be controlled by tidal currents, physiography, water depth, and tidal ranges.

Patterns and Sources of Sediment and Particulate Organic Carbon in Lake Melville, Labrador, Canada: Inferences from 210Pb, 137Cs, and δ13C

NASA Astrophysics Data System (ADS)

Kamula, C. M.

2016-12-01

Modern sedimentological processes, sources and distribution of sediment and organic carbon (OC) were investigated in recently deposited sediment from Lake Melville, Labrador, Canada to better understand the impacts of anthropogenic and climatic changes to the system over the last 100-150 years. Fifteen sediment cores collected across Lake Melville in 2013 and 2014 were analysed for 210Pb and 137Cs while stable isotope δ13Corg and percentage OC were measured down select cores and surface sediment. Mass accumulation rates (MARs) were established by fitting 210Pbex profiles to a two-layer advection diffusion model and validated with 137Cs. MARs varied between 0.04 and 0.41 g cm-2 yr-1 and decreased with distance from the Churchill River, the greatest source of sediment to the system. MARs were greatest in western Lake Melville immediately east of Goose Bay, reflecting the combined contributions of fine material carried eastward in the Churchill River plume and coarser particles from the Kenamu River. The sources of sediment were investigated by comparing inventories of 137Cs and excess 210Pb (210Pbex) to expected atmospheric inputs, which suggested sediment in Lake Melville is largely sourced from the watershed. In the eastern end of Lake Melville, an elevated 210Pbex inventory was associated with particle scavenging of dissolved 210Pb from inflowing marine water and is likely linked to increased primary production in the area. Surface sediment δ13Corg values (mean = -26.2 ± 1.75‰ SD) support a mixture of both terrestrial and marine organic carbon to the system. Using a transient tracer mixing model, the depth in each core corresponding to 90% sediment deposited pre and post hydroelectric development at Churchill Falls (1970) was established and applied to profiles of δ13Corg. This approach revealed an increase of terrestrial OC to Lake Melville post 1970 which we interpret to reflect change in climate and/or hydrology of the Churchill River.

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

PubMed

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

2012-06-01

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

The Roles of Sea-Ice, Light and Sedimentation in Structuring Shallow Antarctic Benthic Communities

PubMed Central

Clark, Graeme F.; Stark, Jonathan S.; Palmer, Anne S.; Riddle, Martin J.; Johnston, Emma L.

2017-01-01

On polar coasts, seasonal sea-ice duration strongly influences shallow marine environments by affecting environmental conditions, such as light, sedimentation, and physical disturbance. Sea-ice dynamics are changing in response to climate, but there is limited understanding of how this might affect shallow marine environments and benthos. Here we present a unique set of physical and biological data from a single region of Antarctic coast, and use it to gain insights into factors shaping polar benthic communities. At sites encompassing a gradient of sea-ice duration, we measured temporal and spatial variation in light and sedimentation and hard-substrate communities at different depths and substrate orientations. Biological trends were highly correlated with sea-ice duration, and appear to be driven by opposing gradients in light and sedimentation. As sea-ice duration decreased, there was increased light and reduced sedimentation, and concurrent shifts in community structure from invertebrate to algal dominance. Trends were strongest on shallower, horizontal surfaces, which are most exposed to light and sedimentation. Depth and substrate orientation appear to mediate exposure of benthos to these factors, thereby tempering effects of sea-ice and increasing biological heterogeneity. However, while light and sedimentation both varied spatially with sea-ice, their dynamics differed temporally. Light was sensitive to the site-specific date of sea-ice breakout, whereas sedimentation fluctuated at a regional scale coincident with the summer phytoplankton bloom. Sea-ice duration is clearly the overarching force structuring these shallow Antarctic benthic communities, but direct effects are imposed via light and sedimentation, and mediated by habitat characteristics. PMID:28076438

The Roles of Sea-Ice, Light and Sedimentation in Structuring Shallow Antarctic Benthic Communities.

PubMed

Clark, Graeme F; Stark, Jonathan S; Palmer, Anne S; Riddle, Martin J; Johnston, Emma L

2017-01-01

On polar coasts, seasonal sea-ice duration strongly influences shallow marine environments by affecting environmental conditions, such as light, sedimentation, and physical disturbance. Sea-ice dynamics are changing in response to climate, but there is limited understanding of how this might affect shallow marine environments and benthos. Here we present a unique set of physical and biological data from a single region of Antarctic coast, and use it to gain insights into factors shaping polar benthic communities. At sites encompassing a gradient of sea-ice duration, we measured temporal and spatial variation in light and sedimentation and hard-substrate communities at different depths and substrate orientations. Biological trends were highly correlated with sea-ice duration, and appear to be driven by opposing gradients in light and sedimentation. As sea-ice duration decreased, there was increased light and reduced sedimentation, and concurrent shifts in community structure from invertebrate to algal dominance. Trends were strongest on shallower, horizontal surfaces, which are most exposed to light and sedimentation. Depth and substrate orientation appear to mediate exposure of benthos to these factors, thereby tempering effects of sea-ice and increasing biological heterogeneity. However, while light and sedimentation both varied spatially with sea-ice, their dynamics differed temporally. Light was sensitive to the site-specific date of sea-ice breakout, whereas sedimentation fluctuated at a regional scale coincident with the summer phytoplankton bloom. Sea-ice duration is clearly the overarching force structuring these shallow Antarctic benthic communities, but direct effects are imposed via light and sedimentation, and mediated by habitat characteristics.

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

PubMed

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

2015-10-01

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

Management of Local Stressors Can Improve the Resilience of Marine Canopy Algae to Global Stressors

PubMed Central

Strain, Elisabeth M. A.; van Belzen, Jim; van Dalen, Jeroen; Bouma, Tjeerd J.; Airoldi, Laura

2015-01-01

Coastal systems are increasingly threatened by multiple local anthropogenic and global climatic stressors. With the difficulties in remediating global stressors, management requires alternative approaches that focus on local scales. We used manipulative experiments to test whether reducing local stressors (sediment load and nutrient concentrations) can improve the resilience of foundation species (canopy algae along temperate rocky coastlines) to future projected global climate stressors (high wave exposure, increasing sea surface temperature), which are less amenable to management actions. We focused on Fucoids (Cystoseira barbata) along the north-western Adriatic coast in the Mediterranean Sea because of their ecological relevance, sensitivity to a variety of human impacts, and declared conservation priority. At current levels of sediment and nutrients, C. barbata showed negative responses to the simulated future scenarios of high wave exposure and increased sea surface temperature. However, reducing the sediment load increased the survival of C. barbata recruits by 90.24% at high wave exposure while reducing nutrient concentrations resulted in a 20.14% increase in the survival and enhanced the growth of recruited juveniles at high temperature. We conclude that improving water quality by reducing nutrient concentrations, and particularly the sediment load, would significantly increase the resilience of C. barbata populations to projected increases in climate stressors. Developing and applying appropriate targets for specific local anthropogenic stressors could be an effective management action to halt the severe and ongoing loss of key marine habitats. PMID:25807516

Sedimentation and basin-fill history of the Neogene clastic succession exposed in the southeastern fold belt of the Bengal Basin, Bangladesh: a high-resolution sequence stratigraphic approach

NASA Astrophysics Data System (ADS)

Royhan Gani, M.; Mustafa Alam, M.

2003-02-01

The Tertiary basin-fill history of the Bengal Basin suffers from oversimplification. The interpretation of the sedimentary history of the basin should be consistent with the evolution of its three geo-tectonic provinces, namely, western, northeastern and eastern. Each province has its own basin generation and sediment-fill history related mainly to the Indo-Burmese and subordinately to the Indo-Tibetan plate convergence. This paper is mainly concerned with facies and facies sequence analysis of the Neogene clastic succession within the subduction-related active margin setting (oblique convergence) in the southeastern fold belt of the Bengal Basin. Detailed fieldwork was carried out in the Sitapahar anticline of the Rangamati area and the Mirinja anticline of the Lama area. The study shows that the exposed Neogene succession represents an overall basinward progradation from deep marine through shallow marine to continental-fluvial environments. Based on regionally correlatable erosion surfaces the entire succession (3000+ m thick) has been grouped into three composite sequences C, B and A, from oldest to youngest. Composite sequence C begins with deep-water base-of-slope clastics overlain by thick slope mud that passes upward into shallow marine and nearshore clastics. Composite sequence B characteristically depicts tide-dominated open-marine to coastal depositional systems with evidence of cyclic marine regression and transgression. Repetitive occurrence of incised channel, tidal inlet, tidal ridge/shoal, tidal flat and other tidal deposits is separated by shelfal mudstone. Most of the sandbodies contain a full spectrum of tide-generated structures (e.g. herringbone cross-bedding, bundle structure, mud couplet, bipolar cross-lamination with reactivation surfaces, 'tidal' bedding). Storm activities appear to have played a subordinate role in the mid and inner shelf region. Rizocorallium, Rosselia, Planolites and Zoophycos are the dominant ichnofacies within the shelfal mudstone. This paralic sedimentation of Neogene succession in the study area can serve as a good point of reference for tide-dominated regressive shelf depositional systems. The top of the composite sequence B is marked by a pronounced erosion surface indicating the final phase of marine regression followed by the gradual establishment of continental-fluvial depositional systems represented by composite sequence A. In this composite sequence, stacked channel bars of low-sinuosity braided rivers gradually pass upsequence into high-sinuosity meandering river deposits. A sequence stratigraphic approach has been adopted to interpret the basin-fill history with respect to relative sea-level changes; and to subdivide the rock record into several sequences and units (systems tracts and parasequences) based on identified bounding discontinuities, such as transgressive erosion surface (TES), regressive erosion surface (RES), marine flooding surface (MFS), and incised valley floor (IVF). This approach provides new insight for both exploration and exploitation strategy for hydrocarbon plays that may prove vital to the oil companies engaged in exploration activities in the Bengal Basin. It is strongly recommended here that the traditional lithostratigraphic classification of this part of the basin, which is based on the Assam stratigraphy, be abandoned or at least revised. A tentative allostratigraphic scheme is presented, and it is suggested that to formalize the scheme further study, both surface and subsurface, is needed.

Simulated oil release from oil-contaminated marine sediment in the Bohai Sea, China.

PubMed

Yuan, Lingling; Han, Longxi; Bo, Wenjie; Chen, Hua; Gao, Wenshen; Chen, Bo

2017-05-15

There is a high degree of heavy oil partitioning into marine sediments when an oil spill occurs. Contaminated sediment, as an endogenous pollution source, can re-pollute overlying water slowly. In this study, a static oil release process and its effects in marine sediment was investigated through a series of experiments with reproductive heavy oil-contaminated marine sediment. The oil release process was accurately simulated with a Lagergren first-order equation and reached equilibration after 48h. The fitted curve for equilibrium concentration (C 0 ) and first-order rate constant (k 1 ) for sediment pollution levels exhibited a first-order log relationship. The instantaneous release rate (dC t dt) was also calculated. The C 0 increased with increases in temperature and dissolved organic matter (DOM), and decreasing salinity. The k 1 increased with temperature, but was not affected by DOM and salinity. These results can be used to better understand the fate of heavy oil in contaminated sediments of the Bohai Sea. Copyright © 2017. Published by Elsevier Ltd.

Estimating growth rates of uncultivated clades of archaea and bacteria in marine sediments

NASA Astrophysics Data System (ADS)

Lloyd, K. G.

2016-12-01

The vast majority of microbes present in marine sediments have never been cultivated in laboratory conditions. It is therefore difficult to estimate the growth rates of these organisms in situ. Quantitative PCR (qPCR) and 16S rRNA gene libraries from sediments below 10 cm show very little change in abundance of these organisms with depth or with redox conditions. Therefore, we hypothesized that uncultivated clades of bacteria and archaea that are ubiquitous in marine sediments, actually grow in the upper 10 cm of marine sediments. We collected sediment cores from the White Oak River estuary, sectioned them in 1 cm intervals, and examined the changes in abundance of uncultivated microbes with depth using 16S rRNA gene libraries and qPCR. We found that some of the key clades associated with the deep subsurface microbiome, such as Bathyarchaeota and MBG-D, increase in abundance with depth, demonstrating extremely slow growth in these shallow subsurface sediments.

Confounding effects of oxygen and temperature on the TEX86 signature of marine Thaumarchaeota

PubMed Central

Qin, Wei; Carlson, Laura T.; Armbrust, E. Virginia; Devol, Allan H.; Moffett, James W.; Stahl, David A.; Ingalls, Anitra E.

2015-01-01

Marine ammonia-oxidizing archaea (AOA) are among the most abundant of marine microorganisms, spanning nearly the entire water column of diverse oceanic provinces. Historical patterns of abundance are preserved in sediments in the form of their distinctive glycerol dibiphytanyl glycerol tetraether (GDGT) membrane lipids. The correlation between the composition of GDGTs in surface sediment and the overlying annual average sea surface temperature forms the basis for a paleotemperature proxy (TEX86) that is used to reconstruct surface ocean temperature as far back as the Middle Jurassic. However, mounting evidence suggests that factors other than temperature could also play an important role in determining GDGT distributions. We here use a study set of four marine AOA isolates to demonstrate that these closely related strains generate different TEX86–temperature relationships and that oxygen (O2) concentration is at least as important as temperature in controlling TEX86 values in culture. All of the four strains characterized showed a unique membrane compositional response to temperature, with TEX86-inferred temperatures varying as much as 12 °C from the incubation temperatures. In addition, both linear and nonlinear TEX86–temperature relationships were characteristic of individual strains. Increasing relative abundance of GDGT-2 and GDGT-3 with increasing O2 limitation, at the expense of GDGT-1, led to significant elevations in TEX86-derived temperature. Although the adaptive significance of GDGT compositional changes in response to both temperature and O2 is unclear, this observation necessitates a reassessment of archaeal lipid-based paleotemperature proxies, particularly in records that span low-oxygen events or underlie oxygen minimum zones. PMID:26283385

Controls on the barium isotope compositions of marine sediments

NASA Astrophysics Data System (ADS)

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 δ 138/134Ba ≈ + 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 Δ diss-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.

Meteoric 10Be/9Be ratios in marine sedimentary records: Deciphering the mixing between their marine and terrestrial sources and influence of costal trace metal fluxes

NASA Astrophysics Data System (ADS)

Wittmann, H.; von Blanckenburg, F.; Mohtadi, M.; Christl, M.; Bernhardt, A.

2017-12-01

Meteoric 10Be to stable 9Be ratios combine a cosmogenic nuclide produced in the atmosphere at a rate known from reconstructions of magnetic field strength with a stable isotope that records the present and past continental weathering and erosion flux. In seawater, the 10Be/9Be ratio provides important information on metal release from bottom sediments, called boundary exchange, and the oceanic mixing of reactive trace metals due to the inherently different sources of the two isotopes. When measured in the authigenic phase of marine sediments, the 10Be/9Be ratio allows deriving the feedbacks between erosion, weathering, and climate in the geologic past. At an ocean margin site 37°S offshore Chile, we use the 10Be/9Be ratio to trace changes in terrestrial particulate composition due to exchange with seawater. We analyzed the reactive (sequentially extracted) phase of marine surface sediments along a coast-perpendicular transect, and compared to samples from their riverine source. We find evidence for growth of authigenic rims through co-precipitation, not via reversible adsorption, that incorporate an open ocean 10Be/9Be signature from a deep water source only 30 km from the coast, thereby overprinting terrestrial riverine 10Be/9Be signatures. We show that the measured 10Be/9Be ratios in marine sediments comprise a mixture between seawater-derived and riverine-sourced phases. As 10Be/9Be ratios increase due to exchange with seawater, particulate-bound Fe concentrations increase, which we attribute to release of Fe-rich pore waters during boundary exchange in the sediment. The implications for the use of 10Be/9Be in sedimentary records for paleo-denudation flux reconstructions are that in coast-proximal sites that are neither affected by deeper water nor by narrow boundary currents, the authigenic record will be a direct recorder of terrigenous denudation of the adjacent river catchments. Hence archive location and past oceanic circulation have to be accounted for when reconstructing continental erosion and weathering, and only at open ocean sites that are fully reset by seawater global signals can be reconstructed.

The physical characteristics of the sediments on and surrounding Dauphin Island, Alabama

USGS Publications Warehouse

Ellis, Alisha M.; Marot, Marci E.; Smith, Christopher G.; Wheaton, Cathryn J.

2017-06-20

Scientists from the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center collected 303 surface sediment samples from Dauphin Island, Alabama, and the surrounding water bodies in August 2015. These sediments were processed to determine physical characteristics such as organic content, bulk density, and grain-size. The environments where the sediments were collected include high and low salt marshes, washover deposits, dunes, beaches, sheltered bays, and open water. Sampling by the USGS was part of a larger study to assess the feasibility and sustainability of proposed restoration efforts for Dauphin Island, Alabama, and assess the island’s resilience to rising sea level and storm events. The data presented in this publication can be used by modelers to attempt validation of hindcast models and create predictive forecast models for both baseline conditions and storms. This study was funded by the National Fish and Wildlife Foundation, via the Gulf Environmental Benefit Fund.This report serves as an archive for sedimentological data derived from surface sediments. Downloadable data are available as Excel spreadsheets, JPEG files, and formal Federal Geographic Data Committee metadata.

Contaminant profiles for surface water, sediment, flora and fauna associated with the mangrove fringe along middle and lower eastern Tampa Bay.

PubMed

Lewis, M A; Russell, M J

2015-06-15

Contaminant concentrations are reported for surface water, sediment, flora and fauna collected during 2010-2011 from the mangrove fringe along eastern Tampa Bay, Florida. Concentrations of trace metals, chlorinated pesticides, atrazine, total polycyclic aromatic hydrocarbons, and polychlorinated biphenyls were species-, chemical- and location-specific. Contaminants in sediments did not exceed proposed individual sediment quality guidelines. Most sediment quality assessment quotients were less than one indicating the likelihood of no inhibitory effect based on chemical measurements alone. Faunal species typically contained more contaminants than plant species; seagrass usually contained more chemicals than mangroves. Bioconcentration factors for marine angiosperms were usually less than 10 and ranged between 1 and 31. Mercury concentrations (ppm) in blue crabs and fish did not exceed the U.S. Environmental Protection Agency fish tissue criterion of 0.3 and the U.S. Food and Drug Administration action level of 1.0. In contrast, total mercury concentrations in faunal species often exceeded guideline values for wildlife consumers of aquatic biota. Published by Elsevier Ltd.

Post-depositional formation of vivianite-type minerals alters sediment phosphorus records

NASA Astrophysics Data System (ADS)

Dijkstra, Nikki; Hagens, Mathilde; Egger, Matthias; Slomp, Caroline P.

2018-02-01

Phosphorus (P) concentrations in sediments are frequently used to reconstruct past environmental conditions in freshwater and marine systems, with high values thought to be indicative of a high biological productivity. Recent studies suggest that the post-depositional formation of vivianite, an iron(II)-phosphate mineral, might significantly alter trends in P with sediment depth. To assess its importance, we investigate a sediment record from the Bornholm Basin that was retrieved during the Integrated Ocean Drilling Program (IODP) Baltic Sea Paleoenvironment Expedition 347 in 2013, consisting of lake sediments overlain by brackish-marine deposits. Combining bulk sediment geochemistry with microanalysis using scanning electron microscope energy dispersive spectroscopy (SEM-EDS) and synchrotron-based X-ray absorption spectroscopy (XAS), we demonstrate that vivianite-type minerals rich in manganese and magnesium are present in the lake deposits just below the transition to the brackish-marine sediments (at 11.5 to 12 m sediment depth). In this depth interval, phosphate that diffuses down from the organic-rich, brackish-marine sediments meets porewaters rich in dissolved iron in the lake sediments, resulting in the precipitation of iron(II) phosphate. Results from a reactive transport model suggest that the peak in iron(II) phosphate originally occurred at the lake-marine transition (9 to 10 m) and moved downwards due to changes in the depth of a sulfidization front. However, its current position relative to the lake-marine transition is stable as the vivianite-type minerals and active sulfidization fronts have been spatially separated over time. Experiments in which vivianite was subjected to sulfidic conditions demonstrate that incorporation of manganese or magnesium in vivianite does not affect its susceptibility to sulfide-induced dissolution. Our work highlights that post-depositional formation of iron(II) phosphates such as vivianite has the potential to strongly alter sedimentary P records particularly in systems that are subject to environmental perturbation, such as a change in primary productivity, which can be associated with a lake-marine transition.

Methane in Sediments From Three Tropical, Coastal Lagoons on the Yucatan Peninsula, Mexico

NASA Astrophysics Data System (ADS)

Young, B.; Paytan, A.; Miller, L.; Herrera-Silveira, J.

2002-12-01

Tropical wetlands are significant sources of methane (CH4) to the atmosphere, and the majority of research on methane flux and cycling in the tropics has been conducted in fresh-water wetlands and lakes. However, several previous studies have shown that tropical coastal ecosystems can produce significant methane flux to the atmosphere despite the presence of moderate to marine salinities. Information regarding methane cycling within the sediments is crucial to understanding how natural and anthropogenic changes may influence these systems. We measured methane concentrations in sediments from two tropical coastal lagoons during different seasons, as well as in a third, heavily polluted, lagoon (Terminos) during the rainy season. These three lagoons, Celestun, Chelem, and Terminos, have similar vegetation, seasonal temperature and rainfall patterns, and substrate geology, but very different levels of ground water discharge and pollution. Methane concentrations in Celestun and Terminos lagoon showed high spatial variability(> 0.001 to 5 mmol kg-1 wet sediment), while sediments in Chelem Lagoon, which has near marine salinities and little sewage discharge, showed much lower variability of methane concentrations. Methane concentrations in Celestun sediments displayed two predominant patterns: some profiles contained a peak in methane concentration (1 to 2 mmole methane kg-1 wet sediment) between 5 and 15 cm below the surface while the other sediment profiles instead displayed a steady or monotonic increase in methane concentration with depth to approximately 0.025-0.080 mmol kg-1 at 10-15cm below surface followed by stable methane concentrations to the bottom of the cores (20-45 cm below the surface). A subsurface peak in methane concentrations was also found in some locations in Chelem, however, the concentrations were much lower than those measured in Celestun. Previous studies have shown that sewage pollution may drastically increase methane production in tropical coastal ecosystems. Laboratory experiments using sediment from the upper 20 cm in Celestun lagoon resulted in high rates of biogenic production of methane from the addition of trimethylamine, hydrogen, and, while additions of formate and acetate stimulated methane production to a lesser extent. This indicates that methane production in these sediments may be highly responsive to natural or anthropogenic changes in substrate availability. By synthesizing laboratory data and extensive field measurements from the lagoons, we hope to shed light on the factors controlling methane cycling in these sediments, and to better estimate methane flux to the atmosphere from these ecosystems.

Biostratigraphic, chronostratigraphic, and stratigraphic sequence analysis of Lower Tertiary marine sediments of Alabama for indicators of sea-level change

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, P.R.; Baum, G.R.

1991-03-01

Early Eocene to late Oligocene marine sedimentary units in southwestern Alabama were sampled at closely spaced intervals to derive a precise time-stratigraphic framework and to determine the paleoecological and mineralogical responses to fluctuations in sea level. Paleontologic control consisted of planktonic, smaller and larger benthonic foraminifera, calcareous nannofossils, dinoflagellates, and megafossils. Paleomagnetic reversals were delineated in two boreholes which, when supplemented by strontium isotope dates and the biostratigraphic control, provided a robust in situ chronostratigraphy for the Gulf Coast lower Tertiary. Paleoecologic trends in regression and transgression can be clearly correlated across major regional facies changes. Using the chronostratigraphy developedmore » here, the second-, third-, and fourth-orders of Vail's global sea-level cycles can be recognized and demonstrate the influence of sea-level change on sedimentation. Stratigraphic systems tracts (SSTs) and bounding surfaces in outcrop were determined by lithologic variations and paleoecologic trends, and additionally by gamma logs in the cores. The lower sequence boundary occurs at a contact where an older, relatively fine-grained, deep-water, fossiliferous unit was abruptly succeeded by a coarse-grained, shallow-water, poorly fossiliferous unit. The transgressive surface occurs at the base of a fining- and deepening-upwards unit that was commonly glauconitic and very fossiliferous. Transgression culminated with a pulse of planktonic microfossils in a bed having reduced clastic sedimentation; on the log the surface of maximum starvation was marked by a gamma spike.« less

A seasonal and spatial comparison of metals, and stable carbon and nitrogen isotopes, in Chincoteague Bay and the marsh deposits of Assateague Island and the adjacent vicinity, Maryland and Virginia

USGS Publications Warehouse

Ellis, Alisha M.; Smith, Christopher G.

2017-11-28

After Hurricane Sandy, scientists from the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center conducted a seasonal collection of estuarine, marsh, and sandy overwash surface sediments from Chincoteague Bay, Tom’s Cove, and the surrounding Assateague Island and Delmarva Peninsula in March–April and October 2014. Surplus surface sediment was analyzed for metals, percent carbon and nitrogen, δ13C, and δ15N as part of a complementary U.S. Geological Survey Coastal and Marine Geology Program Sea-level and Storm Impacts on Estuarine Environments and Shorelines project study. The geochemical subsample analyzed for metals and stable isotopes at each site may be used for comparison with past data sets, to create a modern baseline of the natural distribution of the area, to understand seasonal variability as it relates to the health of the local environment, and to assess marsh-to-bay interactions. The use of metals, stable carbon, and stable nitrogen isotopes allows for a more cohesive snapshot of factors influencing the environment and could aid in tracking environmental change.This report serves as an archive for chemical data derived from the surface sediment. Data are available for a seasonal comparison between the March–April 2014 and October 2014 sampling trips. Downloadable data are available as Microsoft Excel spreadsheets. These additional files include formal Federal Geographic Data Committee metadata (data downloads).

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

EPA Science Inventory

Marine and estuarine sediments accumulate contaminants and act as a sink for a wide range of toxic chemicals. As a result, the sediments themselves can become a source of contamination. At sufficient levels, contaminated sediments can cause benthic impairments and toxicity to m...

REMOVAL OF AMMONIA TOXCITY IN MARINE SEDIMENT TIES: A COMPARISON OF ULVA LACTUCA, ZEOLITE AND AREATION METHODS

EPA Science Inventory

Ammonia is suspected of causing some of the toxicity observed in marine sediment toxicity tests because it is sometimes found at elevated concentrations in marine interstitial waters. In marine waters, ammonia exists as un-ionized ammonia (NH3) and ammonium (NH4+) which combine ...

The origin of islands in the Kandalaksha Gulf of the White Sea: joint work of internal and external geodynamic processes

NASA Astrophysics Data System (ADS)

Kosevich, Natalia; Romanovskaya, Maria

2016-04-01

The modern White Sea basin is a part of the encounter zone between the East European Platform and of the Fennoscandian Shield. The Kandalaksha Gulf in its northwest lies on the Mesoarchean-Paleoproterozoic structure known as the White Sea Shift Belt. In the Oligocene, it entered its neotectonic stage. Geologically, there are two structural storeys beneath the seafloor of the Kandalaksha Gulf: 1) crystalline bedrock of the Archean White Sea complex; 2) a cover of sediment consisting of three layers: Riphean sandstones, terrigenous Vendian deposits; a cloak of Pleistocene and Holocene deposits and sediments - glacial drifts, transitional glaciomarine sediments and purely marine sediments. The modern White Sea is a young basin formed just 10 to 12 ka. The geological and geomorphic history of the White Sea region was very complicated, with various and often conflicting tectonic movements. Besides the postglacial isostatic rise of Scandinavia amounted to some 100 meters in the White Sea area. The White Sea has numerous islands that are very different in the geological-geomorphological and genetic senses because their origin is the result of interactions between various endogenous and exogenous processes. Large and detailed scale geological and morphological researches of the islands at the southern and northern coast of the Kandalaksha Gulf have been carried out. Landforms of the islands were produced by the joint effects of such processes as (1) glacial-tectonic effects and marine wave action, (2) tidal and surge effects; (3) glacial-tectonic, marine, and gravity effects, and (4) glacial-tectonic, marine, lake, and biogenic effects (Kosevich, 2015). The relief structure of the islands has the following regularities: 1) structures of the northern coast islands are more often landforms that are composed of loose deposits with small sites of structural denudation residual outcrops; 2) the structures of the southern coast islands are typically combinations of loose deposits and bedrock outcrops; structural denudation landforms dominate over the marine and biogenic landforms in this case, rocky surfaces of these islands predominate over others. The relief of islands is a combination of smoothed rounded top bedrock surfaces (massifs) with subhorizontal sites that are covered with loose marine deposits. Analysis of the spatial distribution of the genetic types of islands in the Kandalaksha Gulf has revealed that in the apical part of the gulf all genetic types of islands occur, while upon approaching the mouth, one type (tectonic-glacial-accumulative-denudation with marine reworking) becomes predominant. Thus, geological, structural, geomorphic features of Kandalahksha Gulf islands are the results of the complex interaction of the internal and external geodynamic processes. Kosevich N. Geological-geomorphological types of islands in the Kandalaksha Gulf, White Sea. Moscow Univ. Geol.Bull., 2015, vol. 70, N 4. P. 318-326.

Marine resources. [coastal processes, ice, oceanography, and living marine resources

NASA Technical Reports Server (NTRS)

Tilton, E. L., III

1974-01-01

Techniques have been developed for defining coastal circulation patterns using sediment as a natural tracer, allowing the formulation of new circulation concepts in some geographical areas and, in general, a better capability for defining the seasonal characteristics of coastal circulation. An analytical technique for measurement of absolute water depth based upon the ratios of two MSS channels has been developed. Suspended sediment has found wide use as a tracer, but a few investigators have reported limited success in measuring the type and amount of sediment quantitatively from ERTS-1 digital data. Significant progress has been made in developing techniques for using ERTS-1 data to locate, identify, and monitor sea and lake ice. Ice features greater than 70 meters in width can be detected, and both arctic and antarctic icebergs have been identified. In the application area of living marine resources, the use of ERTS-1 image-density patterns as a potential indicator of fish school location has been demonstrated for one coastal commercial resource, menhaden. ERTS-1 data have been used to locate ocean current boundaries using ERTS-1 image-density enhancement, and some techniques are under development for measurement of suspended particle concentration and chlorophyll concentration. The interrelationship of water color and surface characteristics (sea state) are also being studied to improve spectral and spatial interpretive techniques.

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

PubMed Central

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

2014-01-01

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. PMID:24577351

Distribution of Heavy Metals in Surface Sediments of the Bay of Bengal Coast

PubMed Central

Hasan, M. R.; Khan, M.; Aktar, S.; Fatema, K.

2017-01-01

The concentrations of major (Si, Al, Ca, Fe, and K) and minor (Cd, Mn, Ni, Pb, U, Zn, Co, Cr, As, Cu, Rb, Sr, and Zr,) elements in the surficial sediments were studied in an attempt to establish their concentration in the Bengal coast. It was revealed that the majority of the trace elements have been introduced into the Bengal marine from the riverine inflows that are also affected by the impact of industrial, ship breaking yard, gas production plant, and urban wastes. The concentration of heavy metals was measured using Atomic Absorption Spectroscopy and Energy Dispersive X-ray fluorescence instruments. The highest concentrations for several trace elements were thus recorded which generally decrease with distance from the coast. It was observed that the heavy metal concentrations in the sediments generally met the criteria of international marine sediment quality. However, both the contamination factor and pollution load index values suggested the elevation of some metals' concentrations in the region. Constant monitoring of the Bengal coast water quality needs to be recorded with a view to minimizing the risk of health of the population and the detrimental impacts on the aquatic ecosystem. PMID:28255298

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

PubMed Central

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. PMID:26070156

The linkage between marine sediment records and changes in Holocene Saharan landscape: simulating the dust cycle

NASA Astrophysics Data System (ADS)

Egerer, Sabine; Claussen, Martin; Reick, Christian; Stanelle, Tanja

2016-04-01

Marine sediment records reveal an abrupt and strong increase in dust deposition in the North Atlantic at the end of the African Humid Period about 4.9 ka to 5.5 ka ago (deMenocal et al., 2000; McGee et al., 2013). The change in dust flux has been attributed to varying Saharan land surface cover. Alternatively, the enhanced dust accumulation is linked to enhanced surface winds and a consequent intensification of coastal upwelling. We present simulation results from a recent sensitivity study, where we demonstrate for the first time the direct link between dust accumulation in marine cores and changes in Saharan land surface during the Holocene. We have simulated timeslices of he mid-Holocene (6 ka BP) and pre-industrial (1850 AD) dust cycle as a function of Saharan land surface cover and atmosphere-ocean conditions using the coupled atmosphere-aerosol model ECHAM6.1-HAM2.1. We prescribe mid-Holocene vegetation cover based on a vegetation reconstruction from pollen data (Hoelzmann et al., 1998) and mid-Holocene lake surface area is determined using a water routing and storage model (Tegen et al., 2002). In agreement with data from marine sediment cores, our simulations show that mid-Holocene dust deposition fluxes in the North Atlantic were two to three times lower compared with pre-industrial fluxes. We identify Saharan land surface characteristics to be the main control on dust transport from North Africa to the North Atlantic. We conclude that the variation in dust accumulation in marine cores is likely related to a transition of the Saharan landscape during the Holocene and not due to changes in atmospheric or ocean conditions alone. Reference: deMenocal, P., Ortiz, J., Guilderson, T., Adkins, J., Sarnthein, M., Baker, L., and Yarusinsky, M.: Abrupt onset and termination of the African Humid Period:: rapid climate responses to gradual insolation forcing, Quaternary Science Reviews, 19, 347-361, 2000. Hoelzmann, P., Jolly, D., Harrison, S. P., Laarif, F., Bonnefille, R., and Pachur, H.-J.: Mid-Holocene land-surface conditions in northern Africa and the Arabian Peninsula: A data set for the analysis of biogeophysical feedbacks in the climate system, Global Biogeochemical Cycles, 12, 35-51, doi:10.1029/97GB02733, 1998. McGee, D., deMenocal, P., Winckler, G., Stuut, J., and Bradtmiller, L.: The magnitude, timing and abruptness of changes in North African dust deposition over the last 20,000 yr, Earth and Planetary Science Letters, 371-372, 163-176, doi:http://dx.doi.org/10.1016/j.epsl.2013.03.054, 2013. Tegen, I., Harrison, S. P., Kohfeld, K., Prentice, I. C., Coe, M., and Heimann, M.: Impact of vegetation and preferential source areas on global dust aerosol: Results from a model study, Journal of Geophysical Research: Atmospheres, 107, AAC 14-1-AAC 14-27, doi:10.1029/2001JD000963, 2002.

Increase in Nutrients, Mercury, and Methylmercury as a Consequence of Elevated Sulfate Reduction to Sulfide in Experimental Wetland Mesocosms

NASA Astrophysics Data System (ADS)

Myrbo, A.; Swain, E. B.; Johnson, N. W.; Engstrom, D. R.; Pastor, J.; Dewey, B.; Monson, P.; Brenner, J.; Dykhuizen Shore, M.; Peters, E. B.

2017-11-01

Microbial sulfate reduction (MSR) in both freshwater and marine ecosystems is a pathway for the decomposition of sedimentary organic matter (OM) after oxygen has been consumed. In experimental freshwater wetland mesocosms, sulfate additions allowed MSR to mineralize OM that would not otherwise have been decomposed. The mineralization of OM by MSR increased surface water concentrations of ecologically important constituents of OM: dissolved inorganic carbon, dissolved organic carbon, phosphorus, nitrogen, total mercury, and methylmercury. Increases in surface water concentrations, except for methylmercury, were in proportion to cumulative sulfate reduction, which was estimated by sulfate loss from the surface water into the sediments. Stoichiometric analysis shows that the increases were less than would be predicted from ratios with carbon in sediment, indicating that there are processes that limit P, N, and Hg mobilization to, or retention in, surface water. The highest sulfate treatment produced high levels of sulfide that retarded the methylation of mercury but simultaneously mobilized sedimentary inorganic mercury into surface water. As a result, the proportion of mercury in the surface water as methylmercury peaked at intermediate pore water sulfide concentrations. The mesocosms have a relatively high ratio of wall and sediment surfaces to the volume of overlying water, perhaps enhancing the removal of nutrients and mercury to periphyton. The presence of wild rice decreased sediment sulfide concentrations by 30%, which was most likely a result of oxygen release from the wild rice roots. An additional consequence of the enhanced MSR was that sulfate additions produced phytotoxic levels of sulfide in sediment pore water.

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

EPA Science Inventory

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

Accumulation of deaminated peptides in anoxic sediments of Santa Barbara Basin

NASA Astrophysics Data System (ADS)

Abdulla, Hussain A.; Burdige, David J.; Komada, Tomoko

2018-02-01

Proteins represent the most abundant class of biomolecules in marine sinking particles and microbial biomass, yet their cycling in marine sediments is not fully understood. To investigate whether some portion of hydrolyzed proteins escapes complete remineralization and accumulate in the pore waters, we analyzed dissolved organic matter from the anoxic sediments of Santa Barbara Basin, California, by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR-MS). The results showed an increase in the molecular diversity and abundance of dissolved organic nitrogen (DON) formulas with depth. A comparison of the detected DON formulas to a database of small peptides (2-4 amino acid sequences) returned 119 matches, and these formulas were most abundant near the sediment surface. When we compared our detected formulas to all possible structures that would result from deamination of peptides in the database, we found 680 formula matches. However, these molecular formulas can represent hundreds of different structural isomers (in the present case as many as 3257 different deaminated peptide structures), which cannot be distinguished by the FTICR-MS settings that were used. Analysis of amino acid sequences suggests that these deaminated peptides may be the products of selective degradation of source proteins in marine sediments. We hypothesize that these deaminated peptides accumulate in the pore waters due to extracellular proteinases being inhibited from completely hydrolyzing specific peptides to free amino acids. We suggest that anaerobic microbes deaminate peptides largely to produce H2, which is ultimately used as a reducing agent by other sediment microbes (e.g. CO2 reduction by methanogens). Simple calculations suggest that deaminated peptides may represent ∼25-45% of DOC accumulating in these sediment pore waters. Unlike rapid remineralization of free amino acids, peptide deamination leaves behind the peptide carbon skeleton. Molecular structures of these remnant carbon skeletons may hold important clues about specific microbial processes influencing organic matter remineralization and accumulation.

Using tetraether lipids archived in North Sea Basin sediments to extract North Western European Pliocene continental air temperatures

NASA Astrophysics Data System (ADS)

Dearing Crampton-Flood, Emily; Peterse, Francien; Munsterman, Dirk; Sinninghe Damsté, Jaap S.

2018-05-01

The Pliocene is often regarded as a suitable analogue for future climate, due to an overall warmer climate (2-3 °C) coupled with atmospheric CO2 concentrations largely similar to present values (∼400 ppmv). Numerous Pliocene sea surface temperature (SST) records are available, however, little is known about climate in the terrestrial realm. Here we generated a Pliocene continental temperature record for Northwestern Europe based on branched glycerol dialkyl glycerol tetraether (brGDGT) membrane lipids stored in a marine sedimentary record from the western Netherlands. The total organic carbon (TOC) content of the sediments and its stable carbon isotopic composition (δ13Corg) indicate a strong transition from primarily marine derived organic matter (OM) during the Pliocene, to predominantly terrestrially derived OM after the transition into the Pleistocene. This trend is supported by the ratio of branched and isoprenoid tetraethers (BIT index). The marine-terrestrial transition indicates a likely change in brGDGT sources in the core, which may complicate the applicability of the brGDGT paleotemperature proxy in this setting. Currently, the application of the brGDGT-based paleothermometer on coastal marine sediments has been hampered by a marine overprint. Here, we propose a method to disentangle terrestrial and marine sources based on the degree of cyclization of tetramethylated brGDGTs (#rings) using a linear mixing model based on the global soil calibration set and a newly developed coastal marine temperature transfer function. Application of this method on our brGDGT record resulted in a 'corrected' terrestrial temperature record (MATterr). This latter record indicates that continental temperatures were ∼12-14 °C during the Early Pliocene, and 10.5-12 °C during the Mid Pliocene, confirming other Pliocene pollen based terrestrial temperature estimates from Northern and Central Europe. Furthermore, two colder (Δ 5-7 °C) periods in the Pliocene MATterr record show that the influence of Pliocene glacials reached well into NW Europe.

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

NASA Technical Reports Server (NTRS)

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

1989-01-01

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

Spatial distribution and ecological risk assessment of heavy metals in coastal surface sediments in the Hebei Province offshore area, Bohai Sea, China.

PubMed

Ding, Xigui; Ye, Siyuan; Yuan, Hongming; Krauss, Ken W

2018-06-01

Seven hundred and nine surface sediment samples, along with deeper sediment samples, were collected from Hebei Province along the coastal section of the Bohai Sea, China, and analyzed for grain size, concentrations of organic carbon (Corg) and heavy metals (Cu, Pb, Zn, Cr, Cd, As, and Hg). Results indicated that the average concentrations in the sediments were 16.1 mg/kg (Cu), 19.4 mg/kg (Pb), 50 mg/kg (Zn), 48.8 mg/kg (Cr), 0.1 mg/kg (Cd), 8.4 mg/kg (As), and 20.3 μg/kg (Hg). These concentrations generally met the China Marine Sediment Quality criteria. However, both pollution assessments indicated moderate to strong Cd and Hg contamination in the study area. The potential ecological risk index suggested that the combined ecological risk of the seven studied metals may be low, but that 24.5% of the sites, where sediments were finer and higher in Corg concentration, had high ecological risk in Hg and Cd pollution. Copyright © 2018 Elsevier Ltd. All rights reserved.

Influence of anthropogenic activities on PAHs in sediments in a significant gulf of low-latitude developing regions, the Beibu Gulf, South China Sea: distribution, sources, inventory and probability risk.

PubMed

Li, Pingyang; Xue, Rui; Wang, Yinghui; Zhang, Ruijie; Zhang, Gan

2015-01-15

Fifteen polycyclic aromatic hydrocarbons (PAHs) in 41 surface sediment samples and a sediment core (50 cm) from the Beibu Gulf, a significant low-latitude developing gulf, were analyzed. PAHs concentrations were 3.01-388 ng g(-)(1) (mean 95.5 ng g(-)(1)) in the surface sediments and 10.5-87.1 ng g(-)(1) (average 41.1 ng g(-)(1)) in the sediment core. Source apportionment indicated that PAHs were generated from coke production and vehicular emissions (39.4%), coal and biomass combustion (35.8%), and petrogenic sources (24.8%). PAHs were mainly concentrated in the industrialized and urbanized regions and the harbor, and were transported by atmospheric deposition to the marine matrix. The mass inventory (1.57-2.62t) and probability risk showed sediments here served as an important reservoir but low PAH risk. Different from oil and natural gas in developed regions, coal combustion has always been a significant energy consumption pattern in this developing region for the past 30 years (56 ± 5%). Copyright © 2014 Elsevier Ltd. All rights reserved.

Alkylphenols in surface sediments of the Yellow Sea and East China Sea inner shelf: occurrence, distribution and fate.

PubMed

Duan, Xiao-yong; Li, Yan-xia; Li, Xian-guo; Zhang, Da-hai; Gao, Yi

2014-07-01

Alkylphenols (APs) have been found as ubiquitous environmental pollutants with reproductive and developmental toxicity. In this study, APs in surface sediments of the Yellow Sea (YS) and East China Sea (ECS) inner shelf were analyzed to assess influences of riverine and atmospheric inputs of pollutants on the marine environment. NP concentrations ranged from 349.5 to 1642.8 ng/g (average 890.1 ng/g) in the YS sediments and from 31.3 to 1423.7 ng/g (average 750.1 ng/g) in the ECS inner shelf sediments. NP distribution pattern was mainly controlled by the sedimentary environment. OP concentration was 0.8-9.3 ng/g (average 4.7 ng/g) in the YS sediments and 0.7-11.1 ng/g (average 5.1 ng/g) in the ECS sediments. Assessment of the influence of distances from land on OP concentrations provided evidence for the predominance of coastal riverine and/or atmospheric inputs rather than long-range transport. And the biological pump may play an important role for sequestration of OP in the nearshore area. Copyright © 2013 Elsevier Ltd. All rights reserved.

Bioavailability of sediment-bound contaminants to marine organisms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, B.; Neff, J.

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.

"Recent" macrofossil remains from the Lomonosov Ridge, central Arctic Ocean

NASA Astrophysics Data System (ADS)

Le Duc, Cynthia; de Vernal, Anne; Archambault, Philippe; Brice, Camille; Roberge, Philippe

2016-04-01

The examination of surface sediment samples collected from 17 sites along the Lomonosov Ridge at water depths ranging from 737 to 3339 meters during Polarstern Expedition PS87 in 2014 (Stein, 2015), indicates a rich biogenic content almost exclusively dominated by calcareous remains. Amongst biogenic remains, microfossils (planktic and benthic foraminifers, pteropods, ostracods, etc.) dominate but millimetric to centrimetric macrofossils occurred frequently at the surface of the sediment. The macrofossil remains consist of a large variety of taxa, including gastropods, bivalvia, polychaete tubes, scaphopods, echinoderm plates and spines, and fish otoliths. Among the Bivalvia, the most abundant taxa are Portlandia arctica, Hyalopecten frigidus, Cuspidaria glacilis, Policordia densicostata, Bathyarca spp., and Yoldiella spp. Whereas a few specimens are well preserved and apparently pristine, most mollusk shells displayed extensive alteration features. Moreover, most shells were covered by millimeter scale tubes of the serpulid polychaete Spirorbis sp. suggesting transport from low intertidal or subtidal zone. Both the ecological affinity and known geographic distribution of identified bivalvia as named above support the hypothesis of transportation rather than local development. In addition to mollusk shells, more than a hundred fish otoliths were recovered in surface sediments. The otoliths mostly belong to the Gadidae family. Most of them are well preserved and without serpulid tubes attached to their surface, suggesting a local/regional origin, unlike the shell remains. Although recovered at the surface, the macrofaunal assemblages of the Lomonosov Ridge do not necessarily represent the "modern" environments as they may result from reworking and because their occurrence at the surface of the sediment may also be due to winnowing of finer particles. Although the shells were not dated, we suspect that their actual ages may range from modern to several thousands of years as suggested by the radiocarbon dating of the upper centimeter of the sediment in PS87/030-2 (7792 ± 59 14C years BP), PS87/055-1 (3897 ± 41 14C years BP), and PS87/099-4 (1421 ± 66 14C years BP). Reference Stein, R. (Ed.), 2015. The Expedition PS87 of the Research Vessel Polarstern to the Arctic Ocean in 2014, Reports on Polar and Marine Research 688, Bremerhaven, Alfred Wegener Institute for Polar and Marine Research, 273 pp (http://epic.awi.de/37728/1/BzPM_0688_2015.pdf).

Dispersal of suspended sediments in the turbid and highly stratified Red River plume

NASA Astrophysics Data System (ADS)

van Maren, D. S.; Hoekstra, P.

2005-03-01

The Red River, annually transporting 100 million tons of sediment, flows into a shallow shelf sea where it rapidly deposits most of its sediment on a prograding delta front. Oceanographic cruises were carried out in February-March and July-August 2000 to determine the vertical structure of the Ba Lat river plume and sediment transport patterns on the delta front. The surface waters in the coastal zone were strongly stratified with a low density and high sediment concentration during the larger part of the wet season, caused by low mixing rates of river plumes with ambient water. The river plume is advected to the south by a well-developed coastal current which originates from the river plumes that enter the Gulf of Tonkin North of the Ba Lat and are deflected southward by the Coriolis force. Sediment predominantly leaves the surface plume by settling from suspension and less by mixing of fresh and marine water. A one-dimensional model for plume deposition valid for fair weather conditions indicates that most sediment is deposited within 10 km and southward of the river mouth. Of prime importance for this depositional pattern is the phase relation between river outflow and tidal currents, in combination with the southward surface flow; alongshore advection is very low during outflow of the turbid river plume. The agreement of modeled plume sedimentation patterns with long-term bathymetric changes strongly suggests that fair weather depositional processes determine delta front development. This may be related to the fact that reworking of sediment mainly occurs several months after the peak deposition period; in the meantime sediment compaction and consolidation have increased the shear strength of deposited sediments.

Deep-sea faunal communities associated with a lost intermodal shipping container in the Monterey Bay National Marine Sanctuary, CA.

PubMed

Taylor, Josi R; DeVogelaere, Andrew P; Burton, Erica J; Frey, Oren; Lundsten, Lonny; Kuhnz, Linda A; Whaling, P J; Lovera, Christopher; Buck, Kurt R; Barry, James P

2014-06-15

Carrying assorted cargo and covered with paints of varying toxicity, lost intermodal containers may take centuries to degrade on the deep seafloor. In June 2004, scientists from Monterey Bay Aquarium Research Institute (MBARI) discovered a recently lost container during a Remotely Operated Vehicle (ROV) dive on a sediment-covered seabed at 1281 m depth in Monterey Bay National Marine Sanctuary (MBNMS). The site was revisited by ROV in March 2011. Analyses of sediment samples and high-definition video indicate that faunal assemblages on the container's exterior and the seabed within 10 m of the container differed significantly from those up to 500 m. The container surface provides hard substratum for colonization by taxa typically found in rocky habitats. However, some key taxa that dominate rocky areas were absent or rare on the container, perhaps related to its potential toxicity or limited time for colonization and growth. Ecological effects appear to be restricted to the container surface and the benthos within ∼10 m. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Purification and culture characteristics of 36 benthic marine diatoms isolated from the Solthörn tidal flat (Southern North Sea).

PubMed

Scholz, Bettina

2014-08-01

Marine benthic diatoms growing in biofilms on sediment surfaces generally occur associated with heterotrophic bacteria, whereas modern molecular techniques and analyses of species-specific physiology create a demand for axenic cultures. Numerous benthic diatoms were isolated from surface sediments during a monitoring of the Solthörn tidal flat (southern North Sea, Germany) from May 2008 to May 2009. Of these, around 50% could be purified from the accompanying heterotrophic bacteria using different antibiotics combined with physical separation methods (vortexing, ultrasound). Overall, seven different antibiotics were tested at different concentrations, and a best working protocol was developed. The axenic strains were stable on average for only around 15 months, indicating a symbiotic interaction between the benthic diatoms and the associated bacteria. While most short-term effects during the purification process were restricted to differences in growth rates among xenic and axenic diatom strains, long-term cultivation led to distinct changes in cell volumes and growth characteristics of the axenic strains. © 2014 Phycological Society of America.

Arctic Sediment Transport from Land to Sea - An Integrated Study of Coastal - Marine Processes and Deposits in Dicksonfjorden, Svalbard

NASA Astrophysics Data System (ADS)

Jensen, M.; Choi, K.; Forwick, M.; Howe, J. A.; Husum, K.; Korsun, S.; Maat, D.; Nam, S. I.

2016-12-01

Valleys and fjords are the key transport and storage systems for sediments and biogeochemical elements from high arctic landscapes to the ocean. Sediment and nutrient fluxes are important for the biochemical cycle in the fjords and eventually in the ocean, and are important input data to earth system models. At present, high latitude systems are underrepresented in such models (Russell, 2014). Dicksonfjorden is a fjord in the larger Isfjorden system, Central Spitsbergen, Svalbard. It has no direct glacial input, in contrast to fjords affected by tidewater glaciers. The sediment supply is very high and the inner fjord receives sediment from a tide-influenced delta. This study is part of a multidisciplinary project aiming at mapping and quantifying sediment types and dispersal patterns in present Arctic valley - fjord systems and is the first comprehensive study of the depositional system in Dicksonfjorden. The first field campaign took place in summer 2016, when detailed mapping of the tidal delta and the sea floor in the inner fjord, coring onshore and offshore and sampling for foraminifera, nutrients and microbial abundances were performed. The surface mapping is based on high-resolution drone images, which will be processed to a high-resolution digital elevation model, and the bathymetry and sediment distribution data from the sea floor has been collected with a Gavia Offshore Surveyor AUV, providing high-resolution bathymetry and backscatter data of the seabed. Core transects from the delta surface will be described and compared to marine cores from the fjord basin retrieved from R/V Helmer Hanssen. Sediment accumulation rates will be assessed from 210Pb and 137Cs radionuclides. Preliminary results on the physical and chemical characteristics of the sedimentation system in inner Dicksonfjorden will be presented and implications for the fjord ecosystem will be discussed. References Russell , J.L., 2014. Control on the Latitudinal distribution of climate processes: Results from Earth System Model simulations. AAPG/SEPM Hedberg Research Conference "Latitudinal controls on stratigraphic models and sedimentary concepts, Banff, Alberta, Canada, September 28 - October 1, 2014, Abstract volume, 10-11.

Organic carbon sources across salinity gradients in Chilean Fjords: Reloncaví Fjord ( 41°S) and Southern Patagonian ice fields area ( 48°S)

NASA Astrophysics Data System (ADS)

Placencia, Juan; Llanos, Gustavo; Contreras, Sergio

2017-04-01

The organic matter preserved in marine sediments contains contributions of allochthonous and autochthonous and variable source inputs. Allochthonous sources are terrestrial erosion (including anthropogenic material) of relatively labile and refractory material, while autochthonous sources including marine phytoplankton. In order to establish the sources of the organic matter (allochthonous/autochthonous) and how organic carbon is distributed along a salinity gradient, on this study we examined of organic Carbon/Nitrogen molar ratios (C:N), isotopic composition (δ13C) and n-alkanes (n-C24 to n-C34) in surface sediments from two continuous systems: river-fjord-ocean in Northern Patagonia (41°S-43°S), and glacier-fjord-ocean in central Patagonia (47°S-50°S). The continental inner fjord areas are characterized with sediment enriched in allochthonous organic carbon and high C:N (8-12) and low δ13C values (-23‰ to -26‰). Towards the Pacific Ocean, low C:N (6-7) and high δ13C values (-20‰ to -22‰) suggest prevalent autochthonous marine sources. Estuarine waters with salinity between 2 psu and 30 psu were associated with high C:N and low δ13C values together with odd over even long-chain n-alkane predominance (n-C31, n-C29 and n-C27) in surface sediments. All geochemical proxies suggest a great contribution of terrigenous input by glacier origin rivers, mainly from terrestrial plants in both areas. Our study provides a framework to guide future researches on environmental and climate change on these systems. This study was supported by the Chilean Navy's Hydrographic and Oceanographic Service, the Chilean National Oceanographic Committee through the Grants CONA C19F1308 and C20F1404, and the Research Office at Universidad Católica de la Ssma. Concepción.

A 1200 Year Alkenone-based Reconstruction of Sea Surface Temperature and Marine Productivity in the Southern California Current System from the Medieval Climate Anomaly to Present

NASA Astrophysics Data System (ADS)

O'Mara, N. A.; Kelly, C. S.; Herbert, T.

2017-12-01

Laminated sediment cores taken from the San Lazaro Basin (SLB) (25.18N, 112.66W) located off the coast of Baja California in the subtropical eastern Pacific were geochemically analyzed for alkenone and sterol biomarkers to reconstruct sea surface temperature (SST) and marine productivity from 850-1980 CE. High sedimentation rates, low bottom water dissolved oxygen, and high marine productivity in combination with the San Lazaro Basin's location within the dynamic transition zone between the tropical and subtropical eastern Pacific, make it a prime location to study variability of tropical and subtropical modes of climate variability. This study focuses on the impacts and variability of the El Niño Southern Oscillation and the Pacific Decadal Oscillation on the subtropical eastern Pacific. SST and coccolithophore productivity (n=730) for 2 mm sections of sediment corresponding to 1 measurement every 1.8 years were reconstructed using the Uk'37 unsaturation index and C37 alkenone concentration. The high resolution of this record allowed for the analysis of variability of SST and productivity on decadal timescales. Brassicasterol concentrations were calculated for a limited number of samples (n=44) to assess diatom productivity. High spectral power was found at periods of 20-30 years in SST and productivity records indicating a strong influence of the PDO on the SLB, making this the first marine based record directly relevant to PDO reconstructions that continuously spans the last millennium. Cool and productive (warm and less productive) waters were observed in the southern California Current in the Medieval Climate Anomaly 900-1200 CE (Little Ice Age 1400-1800 CE) supporting previous reconstructions that warmer (cooler) SST are linked to both reduced (enhanced) phytoplankton productivity. Additionally, cool (warm) SST were also associated with dry (wet) conditions in the American Southwest indicating that changes in the PDO has had a significant impact on drought in this region over the past millennium.

Intense molybdenum accumulation in sediments underneath a nitrogenous water column and implications for the reconstruction of paleo-redox conditions based on molybdenum isotopes

NASA Astrophysics Data System (ADS)

Scholz, Florian; Siebert, Christopher; Dale, Andrew W.; Frank, Martin

2017-09-01

The concentration and isotope composition of molybdenum (Mo) in sediments and sedimentary rocks are widely used proxies for anoxic conditions in the water column of paleo-marine systems. While the mechanisms leading to Mo fixation in modern restricted basins with anoxic and sulfidic (euxinic) conditions are reasonably well constrained, few studies have focused on Mo cycling in the context of open-marine anoxia. Here we present Mo data for water column particulate matter, modern surface sediments and a paleo-record covering the last 140,000 years from the Peruvian continental margin. Mo concentrations in late Holocene and Eemian (penultimate interglacial) shelf sediments off Peru range from ∼70 to 100 μg g-1, an extent of Mo enrichment that is thought to be indicative of (and limited to) euxinic systems. To investigate if this putative anomaly could be related to the occasional occurrence of sulfidic conditions in the water column overlying the Peruvian shelf, we compared trace metal (Mo, vanadium, uranium) enrichments in particulate matter from oxic, nitrate-reducing (nitrogenous) and sulfidic water masses. Coincident enrichments of iron (Fe) (oxyhydr)oxides and Mo in the nitrogenous water column as well as co-variation of dissolved Fe and Mo in the sediment pore water suggest that Mo is delivered to the sediment surface by Fe (oxyhydr)oxides. Most of these precipitate in the anoxic-nitrogenous water column due to oxidation of sediment-derived dissolved Fe with nitrate as a terminal electron acceptor. Upon reductive dissolution in the surface sediment, a fraction of the Fe and Mo is re-precipitated through interaction with pore water sulfide. The Fe- and nitrate-dependent mechanism of Mo accumulation proposed here is supported by the sedimentary Mo isotope composition, which is consistent with Mo adsorption onto Fe (oxyhydr)oxides. Trace metal co-variation patterns as well as Mo and nitrogen isotope systematics suggest that the same mechanism of Mo delivery caused the 'anomalously' high interglacial Mo accumulation rates in the paleo-record. Our findings suggest that Fe- and nitrate-dependent Mo shuttling under nitrogenous conditions needs to be considered a possible reason for sedimentary Mo enrichments during past periods of widespread anoxia in the open ocean.

Long chain diol index (LDI) as an organic-based sea surface temperature proxy in the Korean East Sea (NW Pacific)

NASA Astrophysics Data System (ADS)

Gal, Jong-Ku; Kim, Jung-Hyun; Kang, Su-Jin; Lee, Dong-Hun; Shin, Kyung-Hoon

2016-04-01

Long chain diol index (LDI) was introduced as an organic-based sea surface temperature (SST) proxy. LDI is expressed as the C30 1,15-diol abundance relative to those of C28 1,13-, C30 1,13- and C30 1,15-diols. There were a few studies which accessed the potential of LDI based on the culture, core top sediments, suspended particulate organic matters, and down-core sediments. However it is still unknown about the source of the diols and robustness as the SST proxy in the various marine environments. In the current study, we examined the applicability of the LDI in the East Sea of Korea where productivity and thus sedimentation rates are high. We will compare the LDI data with those of alkenone-based UK'37 by analyzing two multicores covering the last 100 year.

Distribution and pollution assessment of heavy metals in surface sediments in Xiaoqing river estuary and its adjacent sea of Laizhou bay

NASA Astrophysics Data System (ADS)

Wang, Li; Luo, Xianxiang; Fan, Yuqing

2018-03-01

In this paper, the monitoring results of four heavy metals Cu, Pb, Zn and Hg at 10 sampling stations in Xiaoqing river estuary and its adjacent sea of Laizhou Bay in November 2008 were analyzed and evaluated. The results showed that the concentrations of heavy metals in the steam channel and estuary are higher than those in the adjacent sea, and the metal concentrations were below the standard for I class of marine sediment quality, excepting the station 2 in the steam channel and station 5 in the estuary. The assessment of the single-factor pollution index showed that the overall pollution level of the study area was relatively low, but there was serious pollution phenomenon in individual station. The potential ecological risk of heavy metals in the surface sediments was generally at a low level, and Hg had the highest potential risk.

Modification of the Quaternary stratigraphic framework of the inner-continental shelf by Holocene marine transgression: An example offshore of Fire Island, New York

USGS Publications Warehouse

Schwab, William C.; Baldwin, Wayne E.; Denny, Jane F.; Hapke, Cheryl J.; Gayes, Paul T.; List, Jeffrey; Warner, John C.

2014-01-01

The inner-continental shelf off Fire Island, New York was mapped in 2011 using interferometric sonar and high-resolution chirp seismic-reflection systems. The area mapped is approximately 50 km long by 8 km wide, extending from Moriches Inlet to Fire Island Inlet in water depths ranging from 8 to 32 m. The morphology of this inner-continental shelf region and modern sediment distribution patterns are determined by erosion of Pleistocene glaciofluvial sediments during the ongoing Holocene marine transgression; much of the shelf is thus an actively forming ravinement surface. Remnants of a Pleistocene outwash lobe define a submerged headland offshore of central Fire Island. East of the submerged headland, relatively older Pleistocene outwash is exposed over much of the inner-continental shelf and covered by asymmetric, sorted bedforms interpreted to indicate erosion and westward transport of reworked sediment. Erosion of the eastern flank of the submerged Pleistocene headland over the last ~ 8000 years yielded an abundance of modern sand that was transported westward and reworked into a field of shoreface-attached ridges offshore of western Fire Island. West of the submerged headland, erosion of Pleistocene outwash continues in troughs between the sand ridges, resulting in modification of the lower shoreface. Comparison of the modern sand ridge morphology with the morphology of the underlying ravinement surface suggests that the sand ridges have moved a minimum of ~ 1000 m westward since formation. Comparison of modern sediment thickness mapped in 1996–1997 and 2011 allows speculation that the nearshore/shoreface sedimentary deposit has gained sediment at the expense of deflation of the sand ridges.

Quantification of Hydroxylated Polybrominated Diphenyl Ethers (OH-BDEs), Triclosan, and Related Compounds in Freshwater and Coastal Systems

PubMed Central

Kerrigan, Jill F.; Engstrom, Daniel R.; Yee, Donald; Sueper, Charles; Erickson, Paul R.; Grandbois, Matthew; McNeill, Kristopher; Arnold, William A.

2015-01-01

Hydroxylated polybrominated diphenyl ethers (OH-BDEs) are a new class of contaminants of emerging concern, but the relative roles of natural and anthropogenic sources remain uncertain. Polybrominated diphenyl ethers (PBDEs) are used as brominated flame retardants, and they are a potential source of OH-BDEs via oxidative transformations. OH-BDEs are also natural products in marine systems. In this study, OH-BDEs were measured in water and sediment of freshwater and coastal systems along with the anthropogenic wastewater-marker compound triclosan and its photoproduct dioxin, 2,8-dichlorodibenzo-p-dioxin. The 6-OH-BDE 47 congener and its brominated dioxin (1,3,7-tribromodibenzo-p-dioxin) photoproduct were the only OH-BDE and brominated dioxin detected in surface sediments from San Francisco Bay, the anthropogenically impacted coastal site, where levels increased along a north-south gradient. Triclosan, 6-OH-BDE 47, 6-OH-BDE 90, 6-OH-BDE 99, and (only once) 6’-OH-BDE 100 were detected in two sediment cores from San Francisco Bay. The occurrence of 6-OH-BDE 47 and 1,3,7-tribromodibenzo-p-dioxin sediments in Point Reyes National Seashore, a marine system with limited anthropogenic impact, was generally lower than in San Francisco Bay surface sediments. OH-BDEs were not detected in freshwater lakes. The spatial and temporal trends of triclosan, 2,8-dichlorodibenzo-p-dioxin, OH-BDEs, and brominated dioxins observed in this study suggest that the dominant source of OH-BDEs in these systems is likely natural production, but their occurrence may be enhanced in San Francisco Bay by anthropogenic activities. PMID:26466159

Toxicity, Bioaccumulation and Biotransformation of Silver Nanoparticles in Marine Organisms.

EPA Science Inventory

The toxicity, bioaccumulation and biotransformation of citrate and polyvinylpyrrolidone (PVP) coated silver nanoparticles (NPs) (AgNP-citrate and AgNP-PVP) in marine organisms via marine sediment exposure was investigated. Results from 7-d sediment toxicity tests indicate that Ag...

Shelfal sediment transport by undercurrents forces turbidity current activity during high sea level, Chile continental margin

NASA Astrophysics Data System (ADS)

Bernhardt, Anne; Hebbeln, Dierk; Regenberg, Marcus; Lückge, Andreas; Strecker, Manfred. R.

2016-04-01

Understanding the links between terrigenous sediment supply and marine transport and depositional processes along tectonically active margins is essential to decipher turbidite successions as potential archives of climatic and seismic forcings and to comprehend timing and quantity of marine clastic deposition. Sequence stratigraphic models predict coarse-grained terrigenous sediment delivery to deep-marine sites mainly during sea-level fall and lowstand. Marine clastic deposition during periods of transgression and highstand has been attributed to the continued geomorphic connectivity between terrestrial sediment sources and marine sinks (e.g., rivers connected to submarine canyons) often facilitated by narrow shelves, high sediment supply causing delta migration to the shelf edge, and/or abrupt increases in sediment supply due to climatic variability or catastrophic events. To decipher the controls on Holocene highstand turbidite deposition, we analyzed twelve sediment cores of spatially disparate, coeval Holocene turbidite systems along the Chile margin (29-40°S) with changing climatic and geomorphic characteristics but uniform changes of sea level. Intraslope basins in north-central Chile (29-33°S) offshore a narrow to absent shelf record a shut-off of turbidite activity during the Holocene. In contrast, core sites in south-central Chile (36-40°S) offshore a wide continental shelf have repeatedly experienced turbidite deposition during sea-level highstand conditions, even though most of the depocenters are not connected via canyons to sediment sources. The interplay of stable high sediment supply related to strong onshore precipitation in combination with a wide shelf, over which undercurrents move sediment towards the shelf edge, appears to control Holocene turbidite sedimentation and sediment export to the deep sea.

Transfer of radionuclides from high polluted bottom sediments to marine organisms through benthic food chain in post Fukushima period

NASA Astrophysics Data System (ADS)

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 accumulates in a specific tissue called target tissue. This tissue (bone, flesh, stomach, and organs) controls the overall elimination rate of the nuclide in the organism. The model prediction for the coastal area around the FDNPP agree well with observations. In addition the effects from the Chernobyl accident on the Baltic Sea are modelled and these results also are in good agreement with available data. These results demonstrate the importance of the benthic food chain in long-term transfer of radionuclides from high polluted bottom sediments to the marine organisms. The developed model can be applied for different regions of the World Ocean.

Large-Scale Distribution and Activity of Prokaryotes in Deep-Sea Surface Sediments of the Mediterranean Sea and the Adjacent Atlantic Ocean

PubMed Central

Giovannelli, Donato; Molari, Massimiliano; d’Errico, Giuseppe; Baldrighi, Elisa; Pala, Claudia; Manini, Elena

2013-01-01

The deep-sea represents a substantial portion of the biosphere and has a major influence on carbon cycling and global biogeochemistry. Benthic deep-sea prokaryotes have crucial roles in this ecosystem, with their recycling of organic matter from the photic zone. Despite this, little is known about the large-scale distribution of prokaryotes in the surface deep-sea sediments. To assess the influence of environmental and trophic variables on the large-scale distribution of prokaryotes, we investigated the prokaryotic assemblage composition (Bacteria to Archaea and Euryarchaeota to Crenarchaeota ratio) and activity in the surface deep-sea sediments of the Mediterranean Sea and the adjacent North Atlantic Ocean. Prokaryotic abundance and biomass did not vary significantly across the Mediterranean Sea; however, there were depth-related trends in all areas. The abundance of prokaryotes was positively correlated with the sedimentary concentration of protein, an indicator of the quality and bioavailability of organic matter. Moving eastwards, the Bacteria contribution to the total prokaryotes decreased, which appears to be linked to the more oligotrophic conditions of the Eastern Mediterranean basins. Despite the increased importance of Archaea, the contributions of Crenarchaeota Marine Group I to the total pool was relatively constant across the investigated stations, with the exception of Matapan-Vavilov Deep, in which Euryarchaeota Marine Group II dominated. Overall, our data suggest that deeper areas of the Mediterranean Sea share more similar communities with each other than with shallower sites. Freshness and quality of sedimentary organic matter were identified through Generalized Additive Model analysis as the major factors for describing the variation in the prokaryotic community structure and activity in the surface deep-sea sediments. Longitude was also important in explaining the observed variability, which suggests that the overlying water masses might have a critical role in shaping the benthic communities. PMID:24039667

Sorting of Terrestrial and Marine Organic Matter along a Marginal Submarine Canyon: Radiocarbon and Biomarker Signatures of Surface Sediments

NASA Astrophysics Data System (ADS)

Close, H. G.; Doherty, S.; Campbell, P.; McCarthy, M. D.; Prouty, N.

2016-02-01

Submarine canyons are incised features of many continental margins that can have significant influence on the hydrodynamic distribution of sediments and organic matter (OM) eroded and deposited from the continents. Baltimore Canyon, on the U.S. mid-Atlantic margin, contains a complex set of sedimentary processes that simultaneously create unique benthic habitats and control the deposition of OM. Along the canyon axis, loci of net erosion, net deposition, and intense winnowing each host diverse faunal assemblages and varying mixtures of sedimentary OM derived both from production in the overlying water column and from mobilized sediments. Bioavailable components of this deposited OM sustain benthic communities, while recalcitrant components can contribute to long-term carbon burial in the deep sea. Here we probe in detail the terrestrial versus marine origins of OM along a transect of Baltimore Canyon, as well as its bioavailability for benthic fauna, in order to explore how canyon-specific sediment dynamics might emplace a functional sorting of OM from shelf to open ocean. Determining the provenance of sedimentary OM is a continual challenge: commonly-measured bulk geochemical properties often provide insufficient information to distinguish end-member sources. We present a novel approach to separate functional classes of OM and investigate sources and degradative pathways of OM in Baltimore Canyon. In combination with bulk geochemical characteristics, surface sediments from water depths of 200-1200 meters were sequentially extracted (solvent-extracted, acid-hydrolyzed, and demineralized) to separate pools containing different prevalence of terrigenous, marine, and recalcitrant OM. Each class was analyzed for biomarker distributions; amino acid content, 13C signatures, and degradation indicators; bulk carbon and nitrogen isotopes; and radiocarbon content in order to characterize potential end-member sources within the mixture, as well as their age profiles. These geochemical properties were contextualized with accompanying sedimentological and ecological data. Results highlight the importance of coastal proximity, canyon morphology, and local hydrodynamics in determining the bioavailability of benthic organic matter and its potential for long-term carbon burial.

Metal concentrations in surface sediments of Boston Harbor: Changes with time

USGS Publications Warehouse

Bothner, Michael H.; Buchholtz ten Brink, Marilyn R.; Manheim, F.T.

1998-01-01

The concentrations of metals in surface sediments of Boston Harbor have decreased during the period 1977–1993. This conclusion is supported by analysis of: (1) surface sediments collected at monitoring stations in the outer harbor between 1977 and 1993; (2) metal concentration profiles in sediment cores from depositional areas of the harbor; and (3) historical data from a contaminated-sediment database, which includes information on metal and organic contaminants and sediment texture. The background and matrix-corrected concentrations of lead (Pb) measured in the surficial layer (0–2 cm) of cores decreased by an average of 46%±12% among four locations in the outer harbor during the 16 y period. Chromium (Cr), copper (Cu), mercury (Hg), silver (Ag), and zinc (Zn) exhibited similar trends. Results from our sediment sampling are supported by historical data that were compiled from diverse sources into a regional sediment database. This sediment database contains approximately 3000 samples; of these, about 460 samples were collected and analyzed for Cu, Hg, or Zn and many other sediment parameters in Boston Harbor surface sediments between 1971–1993. The database indicates that the concentrations of these three metals also decreased with time in Boston’s Inner Harbor. The decreases in metal concentrations that are observed in more recent years parallel a general decrease in the flux of metals to the harbor, implemented by: (1) ending the sewage sludge discharge to the Harbor in December, 1991; (2) greater source reduction (e.g. recovery of silver from photographic processing) and closing or moving of industries; (3) improvements in wastewater handling and sewage treatment; and (4) diminishing use of lead in gasoline beginning about 1973. Despite the general decrease in metal concentrations in Boston Harbor surface sediments, the concentrations of Ag and Hg measured at some outer harbor stations in 1993 were still at, or above, the level associated with frequent adverse effects to marine organisms (guidelines are: Ag 3.7 μg g−1, Hg 1.17 μg g−1, from Long et al., 1995). Concentrations of the other metals listed were in the range considered to occasionally induce adverse biological effects.

Pacing of deep marine sedimentation in the middle Eocene synorogenic Ainsa Basin, Spanish Pyrenees: deconvolving a 6myr record of tectonic and climate controls

NASA Astrophysics Data System (ADS)

Mac Niocaill, C.; Cantalejo, B.; Pickering, K. T.; Grant, M.; Johansen, K.

2016-12-01

The Middle Eocene thrust-top Ainsa Basin of Northern Spain preserves world-class exposures of deep-marine submarine fan and related deposits. Detailed paleomagnetic, micropaleontologic, and time-series analysis enable us to deconvolve, for the first time in any ancient deep-marine basin worldwide, both the pacing on deposition of the fine-grained interfan sediments and the main sandbodies (submarine fans) through the history of the deep-marine basin. Our magnetostratigraphy and faunal constraints provide a chronological framework for sedimentation in the basin. We use time-series analysis of a range of geochemical and sedimentologic data to identify likely climatic signals in the sedimentary archive. This has enabled us to test the likely importance of climate versus tectonics in controlling deposition. We show that the fine-grained interfan sedimentation preserves a dominant Milankovitch-like cyclicity, whereas the sandbodies (fans) reflect a complex interplay of controls such as tectonics and climate in the sediment source area, including shallow-marine staging areas for sediment redeposition into deeper water. These results not only provide critical information about the timing of substantial coarse clastic delivery into the Ainsa Basin but also give constraints on sediment flux over a 6 Myr window.

Sources, transport and deposition of terrestrial organic material: A case study from southwestern Africa

NASA Astrophysics Data System (ADS)

Herrmann, Nicole; Boom, Arnoud; Carr, Andrew S.; Chase, Brian M.; Granger, Robyn; Hahn, Annette; Zabel, Matthias; Schefuß, Enno

2016-10-01

Southwestern Africa's coastal marine mudbelt, a prominent Holocene sediment package, provides a valuable archive for reconstructing terrestrial palaeoclimates on the adjacent continent. While the origin of terrestrial inorganic material has been intensively studied, the sources of terrigenous organic material deposited in the mudbelt are yet unclear. In this study, plant wax derived n-alkanes and their compound-specific δ13C in soils, flood deposits and suspension loads from regional fluvial systems and marine sediments are analysed to characterize the origin of terrestrial organic material in the southwest African mudbelt. Soils from different biomes in the catchments of the Orange River and small west coast rivers show on average distinct n-alkane distributions and compound-specific δ13C values reflecting biome-specific vegetation types, most notably the winter rainfall associated Fynbos Biome of the southwestern Cape. In the fluvial sediment samples from the Orange River, changes in the n-alkane distributions and compound-specific δ13C compositions reveal an overprint by local vegetation along the river's course. The smaller west coast rivers show distinct signals, reflecting their small catchment areas and particular vegetation communities. Marine surface sediments spanning a transect from the northern mudbelt (29°S) to St. Helena Bay (33°S) reveal subtle, but spatially coherent, changes in n-alkane distributions and compound-specific δ13C, indicating the influence of Orange River sediments in the northern mudbelt, the increasing importance of terrigenous input from the adjacent western coastal biomes in the central mudbelt, and contributions from the Fynbos Biome to the southern mudbelt. These findings indicate the different sources of terrestrial organic material deposited in the mudbelt, and highlight the potential the mudbelt has to preserve evidence of environmental change from the adjacent continent.

A High-Resolution Lipid Biomarker Perspective on North Iceland Shelf Marine Climate over the Last Millennium

NASA Astrophysics Data System (ADS)

Harning, D.; Sepúlveda, J.; Andrews, J. T.; Cabedo-Sanz, P.; Belt, S. T.; Marchitto, T. M.; Stoner, J. S.; Geirsdóttir, Á.; Miller, G. H.

2017-12-01

Icelandic climate is vulnerable to variations in the dominance of competing Arctic and Atlantic ocean currents. The boundary between these water masses delineates the Polar Front, which today occupies the North Iceland Shelf (NIS). To date, Holocene oceanographic reconstructions along the NIS have employed a variety of proxies including Mg/Ca and δ18O of benthic and planktonic foraminifera, quartz and calcite wt%, the alkenone unsaturation index (Uk'37) and biotic species assemblages. Sea surface temperature (SST) proxies are primarily derived from phytoplankton resulting in a seasonal bias toward spring/summer SST. Furthermore, SST proxies can be influenced by additional confounding variables (e.g. salinity, nutrients, depth habitat of biota) resulting in markedly different Holocene temperature reconstructions between proxy datasets. To evaluate the similarities and discrepancies between various marine proxies, we investigate a high-resolution sediment core collected from the central North Iceland Shelf (B997-316GGC, 658 m depth). Sedimentation covers the last millennium, which captures the transition from the Medieval Warm Period to the Little Ice Age. Age control is constrained by 14C dates and paleomagnetic secular variation. To assess marine surface productivity and sea ice conditions, we analyze quartz and calcite wt% via XRD and a series of highly branched isoprenoid biomarkers. Quantitative paleotemperature estimates are derived from a novel combination of Mg/Ca of foraminifera and two lipid biomarker indices, Uk'37 from Prymnesiophyte alkenones and TEX86 from Thaumarchaeota glycerol dialkyl glycerol tetraethers (GDGTs). The latter TEX86 record is the first paleo application in Icelandic waters, which a recent local calibration study suggests may reflect annual or winter sub-surface (0-200 m) temperatures. Our paleotemperature records are bolstered by the analysis of additional sediment core tops, which expand the established Icelandic calibrations. Finally, we perform statistical analyses in an effort to extract a robust record of paleoceanographic change and to test the applicability of various proxies in high-latitude paleoclimate studies.

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

EPA Science Inventory

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

Multiproxy record of the last interglacial (MIS 5e) off central and northern California, U.S.A., from Ocean Drilling Program sites 1018 and 1020

USGS Publications Warehouse

Poore, Richard Z.; Dowsett, H.J.; Barron, J.A.; Heusser, L.; Ravelo, A.C.; Mix, A.

2000-01-01

Environmental and climatic conditions during the last interglacial (about 125,000 years ago) along the Central and Northern California coastal region are interpreted from study of marine cores recovered by the Ocean Drilling Program at sites 1018 and 1020. Marine microfossil and pollen assemblages, oxygen isotopes in benthic foraminifers, physical properties, and calcium carbonate contents of cored sediments are proxies indicating strong links between the marine and terrestrial environments during marine isotope stage 5 (MIS 5). At the beginning of the last interglacial (MIS 5e), reduction in global ice volume, increase in surface temperature, and warming of air temperature along the Central and Northern California coast were synchronous within the resolution of our sampling record.

Geotechnical and Geoacoustic Investigation of Seafloor Sediments on Boston Harbor Approaches

DTIC Science & Technology

2017-01-25

Geoacoustic Investigation of Seafloor Sediments on Boston Harbor Approaches Andrei Abelev Marine Physics Branch Marine Geosciences Division Peter...LIMITATION OF ABSTRACT Geotechnical and Geoacoustic Investigation of Seafloor Sediments on Boston Harbor Approaches Andrei Abelev, Peter Herdic...sampling and analysis series for classification and characterization of the surficial seafloor sediment in the Boston Harbor approaches . 25-01-2017

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

USGS Publications Warehouse

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

2004-01-01

Cenozoic records of Tl isotope compositions recorded by ferromanganese (Fe-Mn) crusts have been obtained. Such records are of interest because recent growth surfaces of Fe-Mn crusts display a nearly constant Tl isotope fractionation relative to seawater. The time-series data are complemented by results for bulk samples and leachates of various marine sediments. Oxic pelagic sediments and anoxic marine deposits can be distinguished by their Tl isotope compositions. Both pelagic clays and biogenic oozes are typically characterized by ??205Tl greater than +2.5, whereas anoxic sediments have ??205Tl of less than -1.5 (??205Tl is the deviation of the 205Tl/203Tl isotope ratio of a sample from NIST SRM 997 Tl in parts per 104). Leaching experiments indicate that the high ??205Tl values of oxic sediments probably reflect authigenic Fe-Mn oxyhydroxides. Time-resolved Tl isotope compositions were obtained from six Fe-Mn crusts from the Atlantic, Indian, and Pacific oceans and a number of observations indicate that these records were not biased by diagenetic alteration. Over the last 25 Myr, the data do not show isotopic variations that significantly exceed the range of Tl isotope compositions observed for surface layers of Fe-Mn crusts distributed globally (??205 Tl=+12.8??1.2). This indicates that variations in deep-ocean temperature were not recorded by Tl isotopes. The results most likely reflect a constant Tl isotope composition for seawater. The growth layers of three Fe-Mn crusts that are older than 25 Ma show a systematic increase of ??205Tl with decreasing age, from about +6 at 60-50 Ma to about +12 at 25 Ma. These trends are thought to be due to variations in the Tl isotope composition of seawater, which requires that the oceans of the early Cenozoic either had smaller output fluxes or received larger input fluxes of Tl with low ??205Tl. Larger inputs of isotopically light Tl may have been supplied by benthic fluxes from reducing sediments, rivers, and/or volcanic emanations. Alternatively, the Tl isotope trends may reflect the increasing importance of Tl fluxes to altered ocean crust through time. ?? 2004 Elsevier B.V. All rights reserved.

Origin and processing of terrestrial organic carbon in the Amazon system: lignin phenols in river, shelf, and fan sediments

NASA Astrophysics Data System (ADS)

Sun, Shuwen; Schefuß, Enno; Mulitza, Stefan; Chiessi, Cristiano M.; Sawakuchi, André O.; Zabel, Matthias; Baker, Paul A.; Hefter, Jens; Mollenhauer, Gesine

2017-05-01

The Amazon River transports large amounts of terrestrial organic carbon (OCterr) from the Andean and Amazon neotropical forests to the Atlantic Ocean. In order to compare the biogeochemical characteristics of OCterr in the fluvial sediments from the Amazon drainage basin and in the adjacent marine sediments, we analysed riverbed sediments from the Amazon mainstream and its main tributaries as well as marine surface sediments from the Amazon shelf and fan for total organic carbon (TOC) content, organic carbon isotopic composition (δ13CTOC), and lignin phenol compositions. TOC and lignin content exhibit positive correlations with Al / Si ratios (indicative of the sediment grain size) implying that the grain size of sediment discharged by the Amazon River plays an important role in the preservation of TOC and leads to preferential preservation of lignin phenols in fine particles. Depleted δ13CTOC values (-26.1 to -29.9 ‰) in the main tributaries consistently correspond with the dominance of C3 vegetation. Ratios of syringyl to vanillyl (S / V) and cinnamyl to vanillyl (C / V) lignin phenols suggest that non-woody angiosperm tissues are the dominant source of lignin in the Amazon basin. Although the Amazon basin hosts a rich diversity of vascular plant types, distinct regional lignin compositions are not observed. In the marine sediments, the distribution of δ13CTOC and Λ8 (sum of eight lignin phenols in organic carbon (OC), expressed as mg/100 mg OC) values implies that OCterr discharged by the Amazon River is transported north-westward by the North Brazil Current and mostly deposited on the inner shelf. The lignin compositions in offshore sediments under the influence of the Amazon plume are consistent with the riverbed samples suggesting that processing of OCterr during offshore transport does not change the encoded source information. Therefore, the lignin compositions preserved in these offshore sediments can reliably reflect the vegetation in the Amazon River catchment. In sediments from the Amazon fan, low lignin content, relatively depleted δ13CTOC values and high (Ad / Al)V ratios indicating highly degraded lignin imply that a significant fraction of the deposited OCterr is derived from petrogenic (sourced from ancient rocks) sources.

Depositional environments during the Late Palaeozoic ice age (LPIA) in northern Ethiopia, NE Africa

NASA Astrophysics Data System (ADS)

Bussert, Robert

2014-11-01

The Late Palaeozoic sediments in northern Ethiopia record a series of depositional environments during and after the Late Paleozoic ice age (LPIA). These sediments are up to 200 m thick and exceptionally heterogeneous in lithofacies composition. A differentiation of numerous types of lithofacies associations forms the basis for the interpretation of a large range of depositional processes. Major glacigenic lithofacies associations include: (1) sheets of diamictite, either overlying glacially eroded basement surfaces or intercalated into the sediment successions, and representing subglacial tillites, (2) thick massive to weakly stratified muddy clast-poor diamictites to lonestone-bearing laminated mudstones originating from a combination of suspension settling of fines and iceberg rainout, (3) lensoidal or thin-bedded diamictites deposited from debris flows, (4) wedges of traction and gravity transported coarse-grained sediments deposited in outwash fans, (5) irregular wedges or sheets of mudstones deformed primarily by extension and incorporating deformed beds or rafts of other lithofacies formed by slumping, and (6) irregular bodies of sandstone, conglomerate and diamictite deformed by glacial pushing. The dominance of laminated or massive clast-bearing mudstones in most successions indicates ice-contact water bodies as the major depositional environment. Into this environment, coarse-grained sediments were transported by various gravity driven transport processes, including dropstone activity of ice-bergs, slumping, cohesive debris flow, hyperconcentrated to concentrated flow, hyperpycnal flow, and by turbidity flow. Close to glacier termini, wedge-shaped bodies of conglomerate, sandstone, diamictite and mudstone were deposited primarily in subaqueous outwash-fans. Soft-sediment deformation of these sediments either records ice push during glacier advance or re-sedimentation by slumping. Apart from an initial glacier advance when thick ice of temperate or polythermal glaciers covered the whole basin, many sections document at least a second major phase of ice advance and retreat, and some sections additional minor advance-retreat cycles. Whether most of the LPIA sediments in northern Ethiopia were deposited in lakes or in fjords is not yet clear. Although univocal evidence of marine conditions is missing, the presence of carbonate-rich beds and the trace fossil assemblage are compatible with a restricted marine environment such as broad palaeofjords affected by strong freshwater discharge during deglaciation. A restricted marine environment for most of the sediments in northern Ethiopia could challenge models of the LPIA sediments in Arabia as primarily glaciolacustrine and glaciofluviatile deposits.

Dissolution and analysis of amorphous silica in marine sediments.

USGS Publications Warehouse

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

1980-01-01

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

Microbial ecological associations in the surface sediments of Bohai strait

NASA Astrophysics Data System (ADS)

Wang, Bin; Liu, Hongmei; Tang, Haitian; Hu, Xiaoke

2017-09-01

Microbial communities play key roles in the marine ecosystem. Despite a few studies on marine microbial communities in deep straits, ecological associations among microbial communities in the sediments of shallow straits have not been fully investigated. The Bohai Strait in northern China (average depth less than 20 m) separates the Bohai Sea from the Yellow Sea and has organic-rich sediments. In this study, in the summer of 2014, six stations across the strait were selected to explore the taxonomic composition of microbial communities and their ecological associations. The four most abundant classes were Gammaproteobacteria, Deltaproteobacteria, Bacilli and Flavobacteriia. Temperature, total carbon, depth, nitrate, fishery breeding and cold water masses influenced the microbial communities, as suggested by representational difference and composition analyses. Network analysis of microbial associations revealed that key families included Flavobacteriaceae, Pirellulaceae and Piscirickettsiaceae. Our findings suggest that the families with high phylogenetic diversity are key populations in the microbial association network that ensure the stability of microbial ecosystems. Our study contributes to a better understanding of microbial ecology in complex hydrological environments.

Changes in detrital input, ventilation and productivity in the central Okhotsk Sea during the marine isotope stage 5e, penultimate interglacial period

NASA Astrophysics Data System (ADS)

Jimenez-Espejo, Francisco J.; García-Alix, Antonio; Harada, Naomi; Bahr, André; Sakai, Saburo; Iijima, Koichi; Chang, Qing; Sato, Keiko; Suzuki, Katsuhiko; Ohkouchi, Naohiko

2018-05-01

By presenting benthic foraminifera isotope profiles and bulk geochemical composition of core sediments, we offer a mutiproxy reconstruction of the central Okhotsk Sea oceanography between ∼130 to and ∼115 kyr, related to the marine isotopic stage 5e (MIS 5e). Sediments from the site MR0604-PC7A have been compared with paleo- sea surface temperatures and other records. This multiparameter approach allowed to recognize three periods for MIS 5e evolution, characterized by variations in marine productivity and bottom oxygenation. These variations have been ultimately associated with the production of Okhotsk Sea Intermediate Water and the presence or absence of nutrient contribution from the Pacific Deep Water into central Okhotsk Sea. Aeolian input reconstructed by Th/Sc ratio indicates higher values during the MIS 6 and MIS 5d compared with the MIS 5e. Eu∗ values indicate an input of detrital material from Kurile Islands and East-Kamchatka during the late MIS 5e, absent during the early MIS 5e and glacial periods.

Geodiversity of a large meander bend in the Little Belt strait in the inner Danish waters

NASA Astrophysics Data System (ADS)

Brandbyge Ernstsen, Verner; Øbro Hansen, Lars; Becker, Marius; Brivio, Lara; Vang, Torben; Lynnerup Trinhammer, Per; Andresen, Katrine Juul; Seidenkrantz, Marit-Solveig; Boldreel, Lars Ole; Bartholdy, Jesper

2017-04-01

The Little Belt strait in the inner Danish waters is characterised by a high biodiversity, and continuous monitoring of flora and fauna and the water quality is undertaken by the authorities. However, the surface sedimentology and geomorphology, i.e. elements of the geodiversity, are less well-constrained. The aim of this study is to investigate the surface sediment and morphology of a large meander bend (with a channel width of 1 km) located between the two bridges crossing the strait (a channel reach of 4 km) in order to assess a potential coupling between geodiversity and biodiversity. More specifically, the objectives are 1) to identify and classify morphological units for creating a geomorphological map, 2) to quantify surface material characteristics for creating a surface material map, and 3) to develop a conceptual model of the substrate and the morphology and morphodynamics in the meander bend between the two bridges in the strait. Preliminary results reveal a diverse morphology in the meander bend; and the annual morphological changes reveal complex sediment transport patterns along and across the bend. Likewise significant sediment sorting trends exist along and across the meander bend. Hence, the preliminary results indicate a high geodiversity in the strait. Acknowledgements The data were collected as part of the MSc course Marine Geoscience, a joint MSc course between the Department of Geosciences and Natural Resource Management at the University of Copenhagen and the Department of Geoscience at Aarhus University. Additional data were included from the research project Control in the Danish Straits 1 (CiDS-1) funded by the Danish Centre for Marine Research (PI Morten Holtegaard). Thanks to the crew on board RV Aurora.

Underwater MASW to evaluate stiffness of water-bottom sediments

USGS Publications Warehouse

Park, C.B.; Miller, R.D.; Xia, J.; Ivanov, J.; Sonnichsen, G.V.; Hunter, J.A.; Good, R.L.; Burns, R.A.; Christian, H.

2005-01-01

The multichannel analysis of surface waves (MASW) is initially intended as a land survey method to investigate the near-surface materials for their elastic properties. The acquired data are first analyzed for dispersion characteristics and, from these the shear-wave velocity is estimated using an inversion technique. Land applications show the potential of the MASW method to map 2D bedrock surface, zones of low strength, Poisson's ratio, voids, as well as to generate shear-wave profiles for various othe geotechnical problems. An overview is given of several underwater applications of the MASW method to characterize stiffness distribution of water-bottom sediments. The first application details the survey under shallow-water (1-6 m) in the Fraser River (Canada). The second application is an innovative experimental marine seismic survey in the North Atlantic Ocean near oil fields in Grand Bank offshore Newfoundland.

Different stages and status of vertical transporting process of Cu in Jiaozhou Bay

NASA Astrophysics Data System (ADS)

Yang, Dongfang; Li, Haixia; Wang, Qi; Zhang, Xiaolong; Ding, Jun

2017-12-01

Understanding the stages and status of vertical transporting process of pollutant in marine bay is essential to pollution control. This paper analyzed the stages and status of Cu’s vertical transporting process in waters in Jiaozhou Bay. Results showed that the vertical transporting process in waters in Jiaozhou Bay included four stages of 1) Cu was imported to the bay by major sources, 2) Cu was transported to surface waters, 3) Cu was transported from surface waters to sediment in sea bottom, and 4) Cu was fixed and buried in sediment. Furthermore, Cu’s vertical transporting process could be divided into seven status in detail, and he characteristics of the vertical transport process of Cu were also analyzed.

Quaternary magnetic excursions recorded in marine sediments.

NASA Astrophysics Data System (ADS)

Channell, J. E. T.

2017-12-01

This year is the golden (50th) anniversary of the first documentation of a magnetic excursion, the Laschamp excursion in volcanics from the Chaine des Puys (Bonhommet and Babkine, 1967). The first recording of an excursion in sediments was from the Blake Outer Ridge (Smith and Foster, 1969). Magnetic excursions are directional aberrations of the geomagnetic field apparently involving short-lived reversal of the main dipole field. They have durations of a few kyrs, and are therefore rarely recorded in sediments with mean sedimentation rates <10 cm/kyr. Certain Brunhes-aged excursions are now well documented having been recorded in both marine sediments and in lavas (Laschamp excursion, 41 ka). Other excursions have not been adequately recorded in lavas, but have been widely recorded in marine and lake sediments (Iceland Basin excursion, 190 ka). The recording of excursions is fortuitous both in lava sequences and in marine sediments due to their millennial/centennial-scale duration, however, the global recording of the Laschamp and Iceland Basin excursions imply that excursions involve the main dipole field, are recorded synchronously over the globe, and are therefore important in stratigraphic correlation. The marine sediment record includes magnetic excursions at 26 ka (Rockall), 32 ka (Mono Lake), 41 ka (Laschamp), 115 ka (Blake), 190 ka (Iceland Basin), 238 ka (Pringle Falls?), 286 ka (Portuguese Orphan), 495 ka (Bermuda), 540 ka (Big Lost), 590 ka (La Palma), and 670 ka (Osaka Bay), implying at least 11 excursions in the Brunhes Chron. For the Matuyama Chron, excursions have been recorded in marine sediments at 868 ka (Kamikatsura?), 932 ka (Santa Rosa), 1051 ka (Intra-Jaramillo), 1115 ka (Punaruu), 1255 ka (Bjorn), 1476 ka (Gardar), 1580 ka (Gilsa), and 2737 ka (Porcupine). Excursions coincide with minima in relative paleointensity (RPI) records. Ages are from correlation of excursion records to oxygen isotope records in the same cores, and ice-volume calibration of the oxygen isotope template. The marine sediment record of excursions, combined with independent documentation of excursions in lavas with Ar/Ar age control, is progressively strengthening our knowledge of the excursion inventory in the Quaternary, and enhancing the importance of excursions and RPI in Quaternary stratigraphy.

Matrix protected organic matter in a river dominated margin: A possible mechanism to sequester terrestrial organic matter?

NASA Astrophysics Data System (ADS)

Mead, Ralph N.; Goñi, Miguel A.

2008-06-01

The provenance of organic matter in surface sediments from the northern Gulf of Mexico was investigated by analyzing the compositions of lipid biomarkers ( n-alkanes, fatty acids, sterols) liberated after a series of chemical treatments designed to remove different organo-mineral matrix associations (i.e. freely extractable, base-hydrolyzable, unhydrolyzable). Bulk analyses of the organic matter (carbon content, carbon:nitrogen ratios, stable and radiocarbon isotopic analyses) were also performed on the intact sediments and their non-hydrolyzable, demineralized residue. We found recognizable lipids from distinct sources, including terrestrial vascular plants, bacteria and marine algae and zooplankton, within each of the isolated fractions. Based on the lipid signatures and bulk compositions, the organic matter within the unhydrolyzable fractions appeared to be the most diagenetically altered, was the oldest in age, and had the highest abundance of terrigenous lipids. In contrast, the base-hydrolyzable fraction was the most diagentically unaltered, had the youngest ages and was most enriched in N and marine lipids. Our results indicate that fresh, autochthonous organic matter is the most important contributor to base-hydrolyzable lipids, whereas highly altered allochthonous sources appear to be predominant source of unhydrolyzable lipids in the surface sediments from the Atchafalaya River shelf. Overall, the lipid biomarker signatures of intact sediments were biased towards the autochthonous source because many of the organic compounds indicative of degraded, terrigenous sources were protected from extraction and saponification by organo-mineral matrices. It is only after these protective matrices were removed by treatment with HCl and HF that these compounds became evident.

ORGANIC CONTAMINANT DISTRIBUTION IN SEDIMENTS, POLYCHAETES (NEREIS VIRENS) AND THE AMERICAN LOBSTER, HOMARUS AMERICANUS IN A LABORATORY FOOD CHAIN EXPERIMENT

EPA Science Inventory

A laboratory experiment was conducted to investigate the transfer of organic contaminants from an environmentally contaminated marine sediment through a simple marine food chain. The infaunal polychaete, Nereis virens, was exposed to contaminated sediment collected from the Passa...

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

EPA Science Inventory

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

INTERLABORATORY COMPARISON OF A REDUCED VOLUME MARINE SEDIMENT TOXICITY TEST METHOD USING AMPHIPOD AMPELISCA ABDITA

EPA Science Inventory

The U.S. Environmental Protection Agency has standardized methods for performing acute marine amphipod sediment toxicity tests. A test design reducing sediment volume from 200 to 50 ml and overlying water from 600 to 150 ml was recently proposed. An interlaboratory comparison wa...

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

EPA Science Inventory

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. ...

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

EPA Science Inventory

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

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

EPA Science Inventory

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

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

EPA Science Inventory

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

Seagrass Impact on Sediment Exchange Between Tidal Flats and Salt Marsh, and The Sediment Budget of Shallow Bays

NASA Astrophysics Data System (ADS)

Donatelli, Carmine; Ganju, Neil Kamal; Fagherazzi, Sergio; Leonardi, Nicoletta

2018-05-01

Seagrasses are marine flowering plants that strongly impact their physical and biological surroundings and are therefore frequently referred to as ecological engineers. The effect of seagrasses on coastal bay resilience and sediment transport dynamics is understudied. Here we use six historical maps of seagrass distribution in Barnegat Bay, USA, to investigate the role of these vegetated surfaces on the sediment storage capacity of shallow bays. Analyses are carried out by means of the Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) numerical modeling framework. Results show that a decline in the extent of seagrass meadows reduces the sediment mass potentially stored within bay systems. The presence of seagrass reduces shear stress values across the entire bay, including unvegetated areas, and promotes sediment deposition on tidal flats. On the other hand, the presence of seagrasses decreases suspended sediment concentrations, which in turn reduces the delivery of sediment to marsh platforms. Results highlight the relevance of seagrasses for the long-term survival of coastal ecosystems, and the complex dynamics regulating the interaction between subtidal and intertidal landscapes.

Phylogenetic Diversity of T4-Type Phages in Sediments from the Subtropical Pearl River Estuary

PubMed Central

He, Maoqiu; Cai, Lanlan; Zhang, Chuanlun; Jiao, Nianzhi; Zhang, Rui

2017-01-01

Viruses are an abundant and active component of marine sediments and play a significant role in microbial ecology and biogeochemical cycling at local and global scales. To obtain a better understanding of the ecological characteristics of the viriobenthos, the abundance and morphology of viruses and the diversity and community structure of T4-type phages were systematically investigated in the surface sediments of the subtropical Pearl River Estuary (PRE). Viral abundances ranged from 4.49 × 108 to 11.7 × 108 viruses/g and prokaryotic abundances ranged from 2.63 × 108 to 9.55 × 108 cells/g, and both decreased from freshwater to saltwater. Diverse viral morphotypes, including tailed, spherical, filamentous, and rod-shaped viruses, were observed using transmission electron microscopy. Analysis of the major capsid gene (g23) indicated that the sediment T4-type phages were highly diverse and, similar to the trend in viral abundances, their diversity decreased as the salinity increased. Phylogenetic analysis suggested that most of the g23 operational taxonomic units were affiliated with marine, paddy soil, and lake groups. The T4-type phage communities in freshwater and saltwater sediments showed obvious differences, which were related to changes in the Pearl River discharge. The results of this study demonstrated both allochthonous and autochthonous sources of the viral community in the PRE sediments and the movement of certain T4-type viral groups between the freshwater and saline water biomes. PMID:28572798

Ground-penetrating radar and differential global positioning system data collected from Long Beach Island, New Jersey, April 2015

USGS Publications Warehouse

Zaremba, Nicholas J.; Smith, Kathryn E.L.; Bishop, James M.; Smith, Christopher G.

2016-08-04

Scientists from the United States Geological Survey, St. Petersburg Coastal and Marine Science Center, U.S. Geological Survey Pacific Coastal and Marine Science Center, and students from the University of Hawaii at Manoa collected sediment cores, sediment surface grab samples, ground-penetrating radar (GPR) and Differential Global Positioning System (DGPS) data from within the Edwin B. Forsythe National Wildlife Refuge–Holgate Unit located on the southern end of Long Beach Island, New Jersey, in April 2015 (FAN 2015-611-FA). The study’s objective was to identify washover deposits in the stratigraphic record to aid in understanding barrier island evolution. This report is an archive of GPR and DGPS data collected from Long Beach Island in 2015. Data products, including raw GPR and processed DGPS data, elevation corrected GPR profiles, and accompanying Federal Geographic Data Committee metadata can be downloaded from the Data Downloads page.

Assessment of chromium and nickel levels in surface sea waters and sediments from industrial marine area in Tuzla Aydinli Bay, Istanbul Turkey.

PubMed

Baysal, Asli; Akman, Suleyman

2018-05-01

The determination and evaluation of nickel and chromium in Tuzla Aydinli Bay is an important subject since it is an industrial marine area for decades and it is crucial to protect aquatic life which are toxic for the aqueous environment. In this study, 32 samples were collected both from near the coastal shipyard activity to far of the activity areas in Tuzla Aydinli Bay, Istanbul (Turkey) according to the standard guidance. Nickel and chromium were determined in the sea water and sediment samples by graphite furnace atomic absorption spectrometry. The contamination factors and geoaccumulation indices with respect to nickel and chromium were calculated and evaluated. Based on the modified ecological risk assessments, variable results were obtained depending on the selection of control (blank) points. Copyright © 2018 Elsevier Ltd. All rights reserved.

High Prevalence of Gammaproteobacteria in the Sediments of Admiralty Bay and North Bransfield Basin, Northwestern Antarctic Peninsula.

PubMed

Franco, Diego C; Signori, Camila N; Duarte, Rubens T D; Nakayama, Cristina R; Campos, Lúcia S; Pellizari, Vivian H

2017-01-01

Microorganisms dominate most Antarctic marine ecosystems, in terms of biomass and taxonomic diversity, and play crucial role in ecosystem functioning due to their high metabolic plasticity. Admiralty Bay is the largest bay on King George Island (South Shetland Islands, Antarctic Peninsula) and a combination of hydro-oceanographic characteristics (bathymetry, sea ice and glacier melting, seasonal entrance of water masses, turbidity, vertical fluxes) create conditions favoring organic carbon deposition on the seafloor and microbial activities. We sampled surface sediments from 15 sites across Admiralty Bay (100-502 m total depth) and the adjacent North Bransfield Basin (693-1147 m), and used the amplicon 454-sequencing of 16S rRNA gene tags to compare the bacterial composition, diversity, and microbial community structure across environmental parameters (sediment grain size, pigments and organic nutrients) between the two areas. Marine sediments had a high abundance of heterotrophic Gammaproteobacteria (92.4% and 83.8% inside and outside the bay, respectively), followed by Alphaproteobacteria (2.5 and 5.5%), Firmicutes (1.5 and 1.6%), Bacteroidetes (1.1 and 1.7%), Deltaproteobacteria (0.8 and 2.5%) and Actinobacteria (0.7 and 1.3%). Differences in alpha-diversity and bacterial community structure were found between the two areas, reflecting the physical and chemical differences in the sediments, and the organic matter input.

Eogenetic siderite as an indicator for fluctuations in sedimentation rate in the Oligocene Boom Clay Formation (Belgium)

NASA Astrophysics Data System (ADS)

Laenen, B.; De Craen, M.

2004-01-01

Horizons with septarian concretions are a salient feature of the marine Boom Clay Formation. At most horizons, the concretions consist of ferroan calcite with variable amounts of pyrite, but at stratigraphic level S60 they also contain siderite. S60 is situated at the centre of an intensely bioturbated zone that is underlain by a pyrite-rich layer. Furthermore, the enclosing clay is strongly enriched in iron, manganese and phosphorous. The sedimentological and chemical zoning is indicative for low sedimentation rates, which allowed the concentration of iron in the aerobic zone of the sediment. Concentration of iron was the prerequisite for the formation of the siderite-containing concretions. The co-precipitation with pyrite is an argument for a formation in the sulphate reduction zone, and is indicative for a high rate of iron-reduction. The latter was due to the rapid burial of the iron-enriched layer below the redox boundary. The abrupt fluctuations in sedimentation rate were a response to the maximum flooding event of the second Rupelian third-order relative sea-level cycle, which caused a brief pushback of the detrital sediment wedge to its source areas. As this response is logically explained by the general sequence stratigraphic model [Spec. Publ.-Soc. Econ. Paleontol. Mineral. 42 (1988) 109], early diagenetic siderite may be widespread at maximum flooding surfaces in rapidly prograding marine mudstones.

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

PubMed

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 rights reserved.

Survival of marine heterotrophic flagellates isolated from the surface and the deep sea at high hydrostatic pressure: Literature review and own experiments

NASA Astrophysics Data System (ADS)

Živaljić, Suzana; Schoenle, Alexandra; Nitsche, Frank; Hohlfeld, Manon; Piechocki, Julia; Reif, Farina; Shumo, Marwa; Weiss, Alexandra; Werner, Jennifer; Witt, Madeleine; Voss, Janine; Arndt, Hartmut

2018-02-01

Although the abyssal seafloor represents the most common benthic environment on Earth, eukaryotic microbial life at abyssal depths is still an uncharted territory. This is in striking contrast to their potential importance regarding the material flux and bacteria consumption in the deep sea. Flagellate genotypes determined from sedimentary DNA deep-sea samples might originate from vital deep-sea populations or from cysts of organisms sedimented down from surface waters. The latter one may have never been active under deep-sea conditions. We wanted to analyze the principal ability of cultivable heterotrophic flagellates of different phylogenetic groups (choanoflagellates, ancyromonads, euglenids, kinetoplastids, bicosoecids, chrysomonads, and cercozoans) to survive exposure to high hydrostatic pressure (up to 670 bar). We summarized our own studies and the few available data from literature on pressure tolerances of flagellates isolated from different marine habitats. Our results demonstrated that many different flagellate species isolated from the surface waters and deep-sea sediments survived drastic changes in hydrostatic pressure. Barophilic behavior was also recorded for several species isolated from the deep sea indicating their possible genetic adaptation to high pressures. This is in accordance with records of heterotrophic flagellates present in environmental DNA surveys based on clone libraries established for deep-sea environments.

Sedimentary framework of Penobscot Bay, Maine

USGS Publications Warehouse

Knebel, Harley J.; Scanlon, Kathryn M.

1985-01-01

Analyses of seismic-reflection profiles, along with previously collected sediment samples and geologic information from surrounding coastal areas, outline the characteristics, distribution, and history of the strata that accumulated within Penobscot Bay, Maine, during the complex period of glaciation, crustal movement, and sea-level change since late Wisconsinan time. Sediments that overlie the rugged, glacially eroded surface of Paleozoic bedrock range in thickness from near zero to more than 50 m and consist of four distinct units.Massive to partly stratified, coarse-grained drift forms thin (< 15 m) isolated patches along the walls and floors of bedrock troughs and constitutes a thick (up to 30 m), hummocky end moraine in the central part of the bay. The drift was deposited by the last ice sheet between 12,700 and 13,500 years ago during deglaciation and coastal submergence (due to crustal depression).Well-stratified, fine-grained glaciomarine deposits are concentrated in bedrock depressions beneath the main passages of the bay. During the period of ice retreat and marine submergence, these sediments settled to the sea floor, draped the irregular underlying surface of bedrock or drift, and accumulated without disturbance by physical or biologic processes.Heterogeneous fluvial deposits fill ancestral channels of the Penobscot River beneath the head of the bay. The channels were incised during a −40 m postglacial low stand of sea level (due to crustal rebound) and later were filled as base level was increased during Holocene time.Muddy marine sediments, which are homogeneous to weakly stratified and rich in organic matter, blanket older deposits within bathymetric depressions in the middle and lower reaches of the bay and cover a pronounced, gently dipping, erosional unconformity in the upper reach. These sediments were deposited during the Holocene transgression as sea level approached its present position and the bay became deeper.Late Wisconsinan and Holocene sedimentation in Penobscot Bay has smoothed the sea floor, but it has not completely obscured the ice-sculptured bedrock topography.

Heavy metals in the surface sediments of the northern portion of the South China Sea shelf: distribution, contamination, and sources.

PubMed

Xu, Fangjian; Tian, Xu; Yin, Feng; Zhao, Yongfang; Yin, Xuebo

2016-05-01

The concentrations of seven heavy metals (Cr, Ni, Cu, Zn, As, Cd, and Pb) in the surface sediments of the northern portion of the South China Sea (SCS) shelf collected between 2012 and 2014 were measured to assess the potential contamination levels and determine the environmental risks that are associated with heavy metals in the area. The measured concentrations in the sediments were 12.4-72.5 mg kg(-1) for Cr, 4.4-29.2 mg kg(-1) for Ni, 7.1-38.1 mg kg(-1) for Cu, 19.3-92.5 mg kg(-1) for Zn, 1.3-12.1 mg kg(-1) for As, 0.03-0.24 mg kg(-1) for Cd, and 8.5-24.4 mg kg(-1) for Pb. These results indicate that the heavy metal concentrations in the sediments generally meet the China Marine Sediment Quality criteria and suggest that the overall sediment quality of the northern portion of the SCS shelf has not been significantly impacted by heavy metal pollution. However, the enrichment factor (EF) and geoaccumulation index (I geo) clearly show that elevated concentrations of Cd occur in the region. A Pearson's correlation analysis was performed, and the results suggest that Cr, Ni, Cu, and Zn have a natural origin; Cd is primarily sourced from anthropogenic activities, with partial lithogenic components, and As and Pb may be affected by factors such as varying input sources or pathways (i.e., coal burning activities and aerosol precipitation). Heavy metal contamination mostly occurred to the east of Hainan Island, mainly because of the rapid economic and social developments in the Hainan Island. The results of this study will be useful for marine environment managers for the remediation of pollution sources.

Immune response of greenback flounder Rhombosolea tapirina after exposure to contaminated marine sediment and diet.

PubMed

Mondon, J A; Duda, S; Nowak, B F

2000-01-01

Non-specific immune response of greenback flounder, Rhombosolea tapirina, exposed to contaminated marine sediments was examined. Reference sediments from Port Sorell and contaminated sediments from Deceitful Cove, Tasmania, Australia were investigated. Hatchery-reared flounder were exposed to reference sediment, contaminated sediment or contaminated sediment and diet for 6 weeks. Phagocytic capacity and lysozyme response in flounder were examined on cessation of exposure trial. Significant differences were found in phagocytic capacity and lysozyme response between treatments. Exposure to contaminated sediment, irrespective of diet or benthic disturbance elicited inhibition of phagocytic efficiency in flounder. Disturbance of contaminated sediment stimulated lysozyme activity. The immune response in flounder indicates potential immunotoxicity of sediment from Deceitful Cove.

Novel reef fabrics from the Devonian Canning Basin, Western Australia

NASA Astrophysics Data System (ADS)

Wood, Rachel

1998-11-01

Large cement-filled cavities (0.2 to 1.5 m wide) are well developed in slope-margin sediments of the spectacular Upper Devonian (Frasnian) reefs of the Canning Basin, Western Australia, where they account for up to 50% of the primary porosity. These are here interpreted as primary reef framework cavities that formed beneath a variety of domal, tabular or laminar stromatoporoid sponges. Of particular note are those created by unusual, very thin (2 to 8 mm), laminar stromatoporoids (mainly Stachyodes australe), that formed arching, hollow domes up to 0.3 m in height and 1.5 m in diameter over the sediment surface to enclose flat-based cavities. The free undersurface of these stromatoporoids often supported a hitherto unrecognised cryptic community, dominated by pendent growth of the putative calcified cyanobacterium Renalcis, with rare intergrown lithistid sponges and spiny atrypid brachiopods. The uneven growth surface of the cryptos imparts an irregular, stromatactis-like texture to the upper surface of the remaining cavity, which is filled by early marine, finely banded, fibrous cements (mainly radiaxial calcite) interbedded with often multiple generations of geopetal sediment containing peloids and ostracod debris. This ecology yields the tabular stromatoporoid- Renalcis fabric described ubiquitously from the Canning Basin reef complex. Such unusual reef fabrics are a consequence of the ecology of shallow marine mid-Palaeozoic reefs which were quite unlike that of modern coral reefs. The frequent preservation of relatively delicate, in situ communities was due to (1) rapid and pervasive early cementation, (2) growth under non-energetic conditions, and (3) the relative insignificance of bioeroders associated with reefs at this time.

Benthic foraminiferal census data from Mobile Bay, Alabama--counts of surface samples and box cores

USGS Publications Warehouse

Richwine, Kathryn A.; Osterman, Lisa E.

2012-01-01

A study was undertaken in order to understand recent environmental change in Mobile Bay, Alabama. For this study a series of surface sediment and box core samples was collected. The surface benthic foraminiferal data provide the modern baseline conditions of the bay and can be used as a reference for changing paleoenvironmental parameters recorded in the box cores. The 14 sampling locations were chosen in the bay to cover the wide diversity of fluvial and marine-influenced environments on both sides of the shipping channel.

Is Ice-Rafted Sediment in a North Pole Marine Record Evidence for Perennial Sea-ice Cover?

NASA Technical Reports Server (NTRS)

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.

Origins and fates of PAHs in the coastal marine environment off San Diego (California)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeng, E.Y.; Yu, C.C.; Vista, C.L.

1995-12-31

The main inputs of anthropogenic hydrocarbons to the coastal marine environment off San Diego include the Point Lama wastewater outfall (City of San Diego), Tijuana River (crossing the boarder between the US and Mexico) and several storm drains along the coastline and in San Diego Bay, inadvertent spills, and aerial deposition. Samples collected (in January and June 1994) from the Point Loma wastewater effluent, Tijuana River runoff, and microlayer, sediment trap, and surface sediment at several locations adjacent to the Point Loma outfall, entrance of Tijuana River into the ocean, and San Diego Bay (near the San Diego International Airport)more » were analyzed to determine the origins and fates of PAHs in the coastal marine environment. Alkyl homologue distributions (AHDS) for naphthalene indicated a mainly petrogenic origin for low molecular-weight PAHs in the effluent, water column particle, and sediment near the outfall. Parent compound distributions (PCDS) for PAHs with molecular weights 178, 202, 228, 252, 276, and 278 showed combustion-related inputs in the water column particle and sediment, especially for mid to high molecular-weight PAHs. PAHs with molecular weight equal to or higher than 252 were not detected in the effluent. The compositions of PAHs were substantially different in the effluent particulates and filtrates, implying a great deal about the fates of PAHs from the outfall and their bioaccumulation by organisms. PAHs detected in Tijuana River runoff had similar AHDs and PCDs to those of the Point Loma outfall effluent. AHDs in the San Diego Bay sediment exhibited marked seasonal variation; low molecular-weight PAHs were significantly combustion-related in January and more petrogenic in June. Microlayer samples generally contained dominant combustion-generated PAHs. The impact of the wastewater outfall discharge on the nearby water column and sediment appeared compromised by other non-point source inputs.« less

Use of neutralized industrial residue to stabilize trace elements (Cu, Cd, Zn, As, Mo, and Cr) in marine dredged sediment from South-East of France.

PubMed

Taneez, Mehwish; Marmier, Nicolas; Hurel, Charlotte

2016-05-01

Management of marine dredged sediments polluted with trace elements is prime issue in the French Mediterranean coast. The polluted sediments possess ecological threats to surrounding environment on land disposal. Therefore, stabilization of contaminants in multi-contaminated marine dredged sediment is a promising technique. Present study aimed to assess the effect of gypsum neutralized bauxaline(®) (bauxite residue) to decrease the availability of pollutants and inherent toxicity of marine dredged sediment. Bauxaline(®), (alumia industry waste) contains high content of iron oxide but its high alkalinity makes it not suitable for the stabilization of all trace elements from multi-contaminated dredged sediments. In this study, neutralized bauxaline(®) was prepared by mixing bauxaline(®) with 5% of plaster. Experiments were carried out for 3 months to study the effect of 5% and 20% amendment rate on the availability of Cu, Cd, Zn, As, Mo, and Cr. Trace elements concentration, pH, EC and dissolved organic carbon were measured in all leachates. Toxicity of leachates was assessed against marine rotifers Brachionus plicatilis. The Results showed that both treatments have immobilization capacity against different pollutants. Significant stabilization of contaminants (Cu, Cd, Zn) was achieved with 20% application rate whereas As, Mo, and Cr were slightly stabilized. Toxicity results revealed that leachates collected from treated sediment were less toxic than the control sediment. These results suggest that application of neutralized bauxaline(®) to dredged sediment is an effective approach to manage large quantities of dredged sediments as well as bauxite residue itself. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2014-01-01

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

Abundance and Distribution of Enteric Bacteria and Viruses in Coastal and Estuarine Sediments—a Review

PubMed Central

Hassard, Francis; Gwyther, Ceri L.; Farkas, Kata; Andrews, Anthony; Jones, Vera; Cox, Brian; Brett, Howard; Jones, Davey L.; McDonald, James E.; Malham, Shelagh K.

2016-01-01

The long term survival of fecal indicator organisms (FIOs) and human pathogenic microorganisms in sediments is important from a water quality, human health and ecological perspective. Typically, both bacteria and viruses strongly associate with particulate matter present in freshwater, estuarine and marine environments. This association tends to be stronger in finer textured sediments and is strongly influenced by the type and quantity of clay minerals and organic matter present. Binding to particle surfaces promotes the persistence of bacteria in the environment by offering physical and chemical protection from biotic and abiotic stresses. How bacterial and viral viability and pathogenicity is influenced by surface attachment requires further study. Typically, long-term association with surfaces including sediments induces bacteria to enter a viable-but-non-culturable (VBNC) state. Inherent methodological challenges of quantifying VBNC bacteria may lead to the frequent under-reporting of their abundance in sediments. The implications of this in a quantitative risk assessment context remain unclear. Similarly, sediments can harbor significant amounts of enteric viruses, however, the factors regulating their persistence remains poorly understood. Quantification of viruses in sediment remains problematic due to our poor ability to recover intact viral particles from sediment surfaces (typically <10%), our inability to distinguish between infective and damaged (non-infective) viral particles, aggregation of viral particles, and inhibition during qPCR. This suggests that the true viral titre in sediments may be being vastly underestimated. In turn, this is limiting our ability to understand the fate and transport of viruses in sediments. Model systems (e.g., human cell culture) are also lacking for some key viruses, preventing our ability to evaluate the infectivity of viruses recovered from sediments (e.g., norovirus). The release of particle-bound bacteria and viruses into the water column during sediment resuspension also represents a risk to water quality. In conclusion, our poor process level understanding of viral/bacterial-sediment interactions combined with methodological challenges is limiting the accurate source apportionment and quantitative microbial risk assessment for pathogenic organisms associated with sediments in aquatic environments. PMID:27847499

Quantification of MTE in surface sediments of Morbihan Coast (South Brittany, France): A preliminary approach for determination of sources and dynamics

NASA Astrophysics Data System (ADS)

Jimenez, Joselyn; Goubert, Evelyne; Labeyrie, Laurent; Coynel, Alexandra; Menier, David

2014-05-01

The Morbihan Coast (South Brittany, France) has an intense coastal activity: farming, industry, urban habitation run-off, yachting and transportation. In the past centuries, tin mining industry was also developed. These different factors may introduce metal trace elements (MTE) into the marine environment at toxic concentration levels. This pollution can particularly affect the oyster production, widely developed in the area. Monitoring MTE in surface sediments at high spatial resolution has been programmed to assess pollutants and their sources in two of the major Morbihan coastal systems concerned with oyster farming, and where available information on MTE impact and sediment quality is limited: the Bay of Quiberon, partly protected from the open ocean by the Quiberon Peninsula and several islands, mostly sandy (coarse to fine, with a significant shelly fraction), with water depths shallower that 25 m, and the Gulf of Morbihan, a shallow depth (less than 5 m, apart from the two paleoriver beds), semi-enclosed, estuarine system with very coarse sand to fine mud, mostly distributed by a strong tidal current system. Fifty two surface sediment samples were collected in April 2013 to characterize the MTE spatial distribution through the salinity and pollution gradients, from the small local rivers and harbor areas to the open marine environments. Analyses cover sedimentological and biogeochemical properties (particulate organic carbon using a LECO-CS-230; MTE using ICP-MS or DMA for Hg). Statistical analyses help to discriminate within the spatial variability the natural (e.g. grain-size effect) and anthropogenic factors. MTE concentrations were also compared to local geochemical background as measured at the bottom of three sediment cores collected in representative sites, for calculating the enrichment index of each MTE and evaluating the degree of sediment contamination. The initial interpretation of the results would indicate a clear distinction between the geochemical gradients linked to natural processes: sediment sources and size fractionation (for example, the relationship between Sr and carbonate concentration in the sand fraction), and gradients linked to polluting factors, in particular in the harbors and protected arias, probably associated with boat maintenance (with Cu, Zn and Sn concentrations exceeding 100 ppm, up to 300 ppm in isolated places). More detailed statistical analyses and implications will be presented at the conference.

Biostratigraphy and paleoecology of the Burdigalian-Serravallian sediments in Wadi Sudr (Gulf of Suez, Egypt): comparison with the Central Paratethys evolution

NASA Astrophysics Data System (ADS)

Ied, Ibrahim M.; Holcová, Katarína; Abd-Elshafy, Ezzat

2011-06-01

Two main Miocene facies were recorded in the Gulf of Suez area: a deep marine and a coastal facies. The analysed sections in the Wadi Sudr area belong to the marine facies. The Lower Miocene (Burdigalian) is represented by coastal, shallow marine sediments, rich in coral, algae, gastropods and large pectinids followed by Langhian open marine sediments and Serravallian lagoonal carbonates. The open marine sediments contain well preserved planktonic and benthic foraminifers and abundant ostracods. The parts of the sections containing foraminifers have been correlated with three planktonic foraminiferal zones (Praeorbulina glomerosa Zone, Orbulina Zone and Globorotalia praemenardii-Globorotalia peripheroronda Zone). Two benthic ecozones were defined (Heterolepa dutemplei-Laevidentalina elegans Zone and Bolivina compressa-Elphidium spp. Zone). Two cycles of sea-level changes can be distinguished and correlated with global sea-level cycles Bur5/Lan1 and Ser1. The first (Langhian) cycle culminated in open marine sublittoral to upper bathyal well aerated sediments. The second (Serravallian) cycle was shallower, littoral suboxic sediments were overlaid by euryhaline carbonates. The studied foraminifera-bearing sediments can be correlated with the lower and Middle Badenian of the Central Paratethys. Though the area of the Gulf of Suez and the Central Paratethys were situated in different climatic zones, and influenced by different tectonic events, the main paleoenvironmental events (sea-level changes, oxygen decrease, salinity changes) are comparable. This correspondence shows that the decisive factors triggering these events were global climatic events.

Carbon nanotubes affect the toxicity of CuO nanoparticles to denitrification in marine sediments by altering cellular internalization of nanoparticle

PubMed Central

Zheng, Xiong; Su, Yinglong; Chen, Yinguang; Wan, Rui; Li, Mu; Huang, Haining; Li, Xu

2016-01-01

Denitrification is an important pathway for nitrate transformation in marine sediments, and this process has been observed to be negatively affected by engineered nanomaterials. However, previous studies only focused on the potential effect of a certain type of nanomaterial on microbial denitrification. Here we show that the toxicity of CuO nanoparticles (NPs) to denitrification in marine sediments is highly affected by the presence of carbon nanotubes (CNTs). It was found that the removal efficiency of total NOX−-N (NO3−-N and NO2−-N) in the presence of CuO NPs was only 62.3%, but it increased to 81.1% when CNTs appeared in this circumstance. Our data revealed that CuO NPs were more easily attached to CNTs rather than cell surface because of the lower energy barrier (3.5 versus 36.2 kT). Further studies confirmed that the presence of CNTs caused the formation of large, incompact, non-uniform dispersed, and more negatively charged CuO-CNTs heteroaggregates, and thus reduced the nanoparticle internalization by cells, leading to less toxicity to metabolism of carbon source, generation of reduction equivalent, and activities of nitrate reductase and nitrite reductase. These results indicate that assessing nanomaterial-induced risks in real circumstances needs to consider the “mixed” effects of nanomaterials. PMID:27279546

Total petroleum hydrocarbons and heavy metals in the surface sediments of Bohai Bay, China: long-term variations in pollution status and adverse biological risk.

PubMed

Zhou, Ran; Qin, Xuebo; Peng, Shitao; Deng, Shihuai

2014-06-15

Surface sediments collected from 2001 to 2011 were analyzed for total petroleum hydrocarbons (TPH) and five heavy metals. The sediment concentration ranges of TPH, Zn, Cu, Pb, Cd and Hg were 6.3-535 μg/g, 58-332 μg/g, 7.2-63 μg/g, 4.3-138 μg/g, 0-0.98μg/g, and 0.10-0.68 μg/g, respectively. These results met the highest marine sediment quality standards in China, indicating that the sediment was fairly clean. However, based on the effects range-median (ERM) quotient method, the calculated values for all of the sampling sites were higher than 0.10, suggesting that there was a potential adverse biological risk in Bohai Bay. According to the calculated results, the biological risk decreased from 2001 to 2007 and increased afterwards. High-risk sites were mainly distributed along the coast. This study suggests that anthropogenic influences might be responsible for the potential risk of adverse biological effects from TPH and heavy metals in Bohai Bay. Copyright © 2014 Elsevier Ltd. All rights reserved.

Paleogeography of the upper Paleozoic basins of southern South America: An overview

NASA Astrophysics Data System (ADS)

Limarino, Carlos O.; Spalletti, Luis A.

2006-12-01

The paleogeographic evolution of Late Paleozoic basins located in southern South America is addressed. Three major types of basins are recognized: infracratonic or intraplate, arc-related, and retroarc. Intraplate basins (i.e., Paraná, Chaco-Paraná, Sauce Grande-Colorado, and La Golondrina) are floored by continental or quasi-continental crust, with low or moderate subsidence rates and limited magmatic and tectonic activity. Arc-related basins (northern and central Chile, Navidad-Arizaro, Río Blanco, and Calingasta-Uspallata basins and depocenters along Chilean Patagonia) show a very complex tectonic history, widespread magmatic activity, high subsidence rates, and in some cases metamorphism of Late Paleozoic sediments. An intermediate situation corresponds to the retroarc basins (eastern Madre de Dios, Tarija, Paganzo, and Tepuel-Genoa), which lack extensive magmatism and metamorphism but in which coeval tectonism and sedimentation rates were likely more important than those in the intraplate region. According to the stratigraphic distribution of Late Paleozoic sediments, regional-scale discontinuities, and sedimentation pattern changes, five major paleogeographic stages are proposed. The lowermost is restricted to the proto-Pacific and retroarc basins, corresponds to the Mississippian (stage 1), and is characterized by shallow marine and transitional siliciclastic sediments. During stage 2 (Early Pennsylvanian), glacial-postglacial sequences dominated the infracratonic (or intraplate) and retroarc basins, and terrigenous shallow marine sediments prevailed in arc-related basins. Stage 3 (Late Pennsylvanian-Early Cisuralian) shows the maximum extension of glacial-postglacial sediments in the Paraná and Sauce Grande-Colorado basins (intraplate region), whereas fluvial deposits interfingering with thin intervals of shallow marine sediments prevailed in the retroarc basins. To the west, arc-related basins were dominated by coastal to deep marine conditions (including turbiditic successions). In the Late Cisuralian (stage 4), important differences in sedimentation patterns are registered for the western arc-related basins and eastern intraplate basins. The former were locally dominated by volcaniclastic sediments or marine deposits, and the intraplate basins are characterized by shallow marine conditions punctuated by several episodes of deltaic progradation. Finally, in the Late Permian (stage 5), volcanism and volcaniclastic sedimentation dominated in basins located along the western South American margin. The intraplate basins in turn were characterized by T-R cycles composed of shallow marine, deltaic, and fluvial siliciclastic deposits.

Harvesting energy from the marine sediment--water interface.

PubMed

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 < 1,000 m deep, and the proven viability of dissolved seawater oxygen as an oxidant for power generation by seawater batteries, it is calculated that optimized power supplies based on the phenomenon demonstrated here could power oceanographic instruments deployed for routine long-term monitoring operations in the coastal ocean.

The formation and evolution of the barrier islands of Inhaca and Bazaruto, Mozambique

NASA Astrophysics Data System (ADS)

Armitage, S. J.; Botha, G. A.; Duller, G. A. T.; Wintle, A. G.; Rebêlo, L. P.; Momade, F. J.

2006-12-01

The barrier islands of Inhaca and Bazaruto are related to the extensive coastal dune system of the Mozambican coastal plain, south-east Africa. Optically stimulated luminescence (OSL) dating of key stratigraphic units indicates that accretion of sediment within these systems is episodic. Both islands appear to have been initiated as spits extending from structural offsets in the coastline. Superposition of significant quantities of sediment upon these spits during subsequent sea-level highstands formed the core of the islands, which were anchored and protected by beachrock and aeolianite formation. At least two distinct dune-building phases occurred during Marine Oxygen Isotope Stage (MIS) 5, tentatively attributed to marine transgressions during sub-stages 5e and 5c. Although some localized reactivation of dune surfaces occurred prior to the Holocene, large quantities of sediment were not deposited on either island during the low sea-levels associated with MIS 2. Significant dune-building and sediment reworking occurred immediately prior to and during the Holocene, though it is not clear whether these processes were continuous or episodic. Significant erosion of the eastern shoreline of Bazaruto suggests that it is far less stable than Inhaca and may suffer further large-scale erosion. A model is presented for the formation of barrier islands along the Mozambican coastal plain.

The Evolution of Sulfide in Shallow Aquatic Ecosystem Sediments: An Analysis of the Roles of Sulfate, Organic Carbon, and Iron and Feedback Constraints Using Structural Equation Modeling

NASA Astrophysics Data System (ADS)

Pollman, C. D.; Swain, E. B.; Bael, D.; Myrbo, A.; Monson, P.; Shore, M. D.

2017-11-01

The generation of elevated concentrations of sulfide in sediment pore waters that are toxic to rooted macrophytes is problematic in both marine and freshwaters. In marine waters, biogeochemical conditions that lead to toxic levels of sulfide generally relate to factors that affect oxygen dynamics or the sediment iron concentration. In freshwaters, increases in surface water sulfate have been implicated in decline of Zizania palustris (wild rice), which is important in wetlands across the Great Lakes region of North America. We developed a structural equation (SE) model to elucidate key variables that govern the evolution of sulfide in pore waters in shallow aquatic habitats that are potentially capable of supporting wild rice. The conceptual basis for the model is the hypothesis that dissimilatory sulfate reduction is limited by the availability of both sulfate and total organic carbon (TOC) in the sediment. The conceptual model also assumes that pore water sulfide concentrations are constrained by the availability of pore water iron and that sediment iron supports the supply of dissolved iron to the pore water. A key result from the SE model is that variations in three external variables (sulfate, sediment TOC, and sediment iron) contribute nearly equally to the observed variations in pore water sulfide. As a result, management efforts to mitigate against the toxic effects of pore water sulfide on macrophytes such as wild rice should approach defining a protective sulfate threshold as an exercise tailored to the geochemistry of each site that quantitatively considers the effects of ambient concentrations of sediment Fe and TOC.

Re-Evaluating the Geological Evidence for Late Holocene Marine Incursion Events along the Guerrero Seismic Gap on the Pacific Coast of Mexico

PubMed Central

Bianchette, Thomas A.

2016-01-01

Despite the large number of tsunamis that impact Mexico’s Pacific coast, stratigraphic studies focusing on geological impacts are scanty, making it difficult to assess the long-term risks for this vulnerable region. Surface samples and six cores were taken from Laguna Mitla near Acapulco to examine sedimentological and geochemical evidence for marine incursion events. Sediment cores collected from behind the beach barrier are dominated by intercalated layers of peat and inorganic sediments, mostly silt and clay, with little or no sand. Sand- and shell-rich clastic layers with high levels of sulfur, calcium, and strontium only occur adjacent to the relict beach ridge remnants near the center of the lagoon. With the exception of one thin fine sand layer, the absence of sand in the near-shore cores and the predominance of the terrigenous element titanium in the inorganic layers, evidently eroded from the surrounding hillslopes, suggests that these large-grained intervals do not represent episodic marine incursions, but rather were likely formed by the erosion and redeposition of older marine deposits derived from the beach ridge remnants when water levels were high. These results do not support the occurrence of a large tsunami event at Laguna Mitla during the Late Holocene. PMID:27571270

Re-Evaluating the Geological Evidence for Late Holocene Marine Incursion Events along the Guerrero Seismic Gap on the Pacific Coast of Mexico.

PubMed

Bianchette, Thomas A; McCloskey, Terrence A; Liu, Kam-Biu

2016-01-01

Despite the large number of tsunamis that impact Mexico's Pacific coast, stratigraphic studies focusing on geological impacts are scanty, making it difficult to assess the long-term risks for this vulnerable region. Surface samples and six cores were taken from Laguna Mitla near Acapulco to examine sedimentological and geochemical evidence for marine incursion events. Sediment cores collected from behind the beach barrier are dominated by intercalated layers of peat and inorganic sediments, mostly silt and clay, with little or no sand. Sand- and shell-rich clastic layers with high levels of sulfur, calcium, and strontium only occur adjacent to the relict beach ridge remnants near the center of the lagoon. With the exception of one thin fine sand layer, the absence of sand in the near-shore cores and the predominance of the terrigenous element titanium in the inorganic layers, evidently eroded from the surrounding hillslopes, suggests that these large-grained intervals do not represent episodic marine incursions, but rather were likely formed by the erosion and redeposition of older marine deposits derived from the beach ridge remnants when water levels were high. These results do not support the occurrence of a large tsunami event at Laguna Mitla during the Late Holocene.

SHORT-EXPOSURE, SUBLETHAL, SEDIMENT TOXICITY TEST USING THE MARINE BIVALVE MULINIA LATERALIS: STATISTICAL DESIGN AND COMPARATIVE SENSITIVITY

EPA Science Inventory

Over the last 10 years a great deal of research effort has concentrated on determining the effects of contaminated sediments on aquatic organisms. or marine systems, this effort has emphasized acute sediment toxicity tests using amphipods, although a variety of other end points a...

Speciation of butyltin compounds in marine sediments with headspace solid phase microextraction and gas chromatography mass spectrometry.

PubMed

Cardellicchio, N; Giandomenico, S; Decataldo, A; Di Leo, A

2001-03-01

A method for the determination of organotin compounds (monobutyl = MBT, dibutyl = DBT, and tributyltin = TBT) in marine sediments by headspace Solid Phase Microextraction (SPME) has been developed. The analytical procedure involved 1) extraction of TBT, DBT and MBT from sediments with HCl and methanol mixture, 2) in situ derivatization with sodium tetraethylborate and 3) headspace SPME extraction using a fiber coated with poly(dimethylsiloxane). The derivatized organotin compounds were desorbed into the splitless injector and simultaneously analyzed by gas chromatography - mass spectrometry. The analytical method was optimized with respect to derivatization reaction and extraction conditions. The detection limits obtained for MBT, DBT and TBT ranged from 730 to 969 pg/g as Sn dry weight. Linear calibration curves were obtained for all analytes in the range of 30-1000 ng/L as Sn. Analysis of a standard reference sediment (CRM 462) demonstrates the suitability of this method for the determination of butyltin compounds in marine sediments. The application to the determination of TBT, DBT and MBT in a coastal marine sediment is shown.

Metabolic Potential of Microbial Genomes Reconstructed from a Deep-Sea Oligotrophic Sediment Metagenome

NASA Astrophysics Data System (ADS)

Tully, B. J.; Huber, J. A.; Heidelberg, J. F.

2016-02-01

The South Pacific Gyre (SPG) possesses the lowest rates of sedimentation, surface chlorophyll concentration and primary productivity in the global oceans, making it one of the most oligotrophic environments on earth. As a direct result of the low-standing biomass in surface waters, deep-sea sediments are thin and contain small amount of labile organic carbon. It was recently shown that the sediment column within the SPG is fully oxic through to the underlying basalt basement and may be representative of 9-37% of the global marine environment. In addition, it appears that approximately 50% of the total organic carbon is removed from the oligotrophic sediments within the first 20 centimeters beneath the sea floor (cmbsf). To understand the microbial processes that contribute to the removal of the labile organic matter, metagenomic sequencing and analysis was carried out on a sample of sediment collected from 0-5 cmbsf from SPG site 10 (U1369). Analysis of 9 partially reconstructed environmental genomes revealed that the members of the SPG surface sediment microbial community are phylogenetically distinct from surface/upper ocean organisms, with deep branches within the Alpha- and Gammaproteobacteria, Nitrospirae, Nitrospina, the phylum NC10, and several unique phylogenetic groups. Within these partially complete genomes there is evidence for microbially mediated metal (iron/manganese) oxidation and carbon fixation linked to the nitrification. Additionally, despite low sedimentation and hypothesized energy-limitation, members of the SPG microbial community had motility and chemotactic genes and possessed mechanisms for the utilization of high molecular weight organic matter, including exoproteases and peptide specific membrane transporters. Simultaneously, the SPG genomes showed a limited potential for the degradation of recalcitrant carbon compounds. Finally, the presence of putative genes with functions involved with denitrification and the consumption of C1 compounds suggest that there may be microenvironments in the surface sediments were microbes can deplete oxygen concentrations to hypoxic/anoxic levels. This study represents an important first analysis in understanding how microorganisms in oligotrophic sediments impact deep-sea carbon transformations.

Bacterial communities in sediment of a Mediterranean marine protected area.

PubMed

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.

Microplastics en route: Field measurements in the Dutch river delta and Amsterdam canals, wastewater treatment plants, North Sea sediments and biota.

PubMed

Leslie, H A; Brandsma, S H; van Velzen, M J M; Vethaak, A D

2017-04-01

Environmental contamination by plastic particles, also known as 'microplastics', brings synthetic materials that are non-degradable and biologically incompatible into contact with ecosystems. In this paper we present concentration data for this emerging contaminant in wastewater treatment plants (WWTPs) and freshwater and marine systems, reflecting the routes via which these particles can travel and the ecosystems they potentially impact along their path. Raw sewage influents, effluents and sewage sludge from seven municipal WWTPs in the Netherlands contained mean particle concentrations of 68-910L -1 , 51-81L -1 and 510-760kg -1 wet weight (ww), respectively (particle sizes between 10 and 5000μm). Even after treatment, wastewater constitutes a source of microplastic pollution of surface waters, and via biosolids applications in farming and forestry, plastic retained in sewage sludge can be transferred to terrestrial environments. The WWTPs investigated here had a mean microplastics retention efficiency of 72% (s.d. 61%) in the sewage sludge. In the receiving waters of treated and untreated wastewaters, we detected high microplastic levels in riverine suspended particulate matter (1400-4900kg -1 dry weight (dw)) from the Rhine and Meuse rivers. Amsterdam canal water sampled at different urban locations contained microplastic concentrations (48-187L -1 ), similar to those observed in wastewater that is emitted from sewage treatment facilities in the area. At least partial settling of the particles occurs in freshwater as well, as indicated by microplastics in urban canal sediments (<68 to 10,500particleskg -1 dw). Microplastics in suspension in the water column have the potential to be discharged into the sea with other riverine suspended particulates. We report microplastic concentrations from 100 up to 3600particleskg -1 dry sediment collected at 15 locations along the Dutch North Sea coast. The high microplastic enrichment in marine sediments compared to most literature data for seawater at the surface supports the hypothesis of a seabed sink for these materials. Marine species are heavily exposed to plastic particles. Body residues between 10 and 100particlesg -1 dw were measured in benthic macroinvertebrate species inhabiting the Dutch North Sea coast: filter-feeding mussels and oysters (species for human consumption) as well as other consumers in the marine food chain. Copyright © 2017 Elsevier Ltd. All rights reserved.

Soils on raised marine terraces in the Metaponto area, S Italy: not a simple chronosequence

NASA Astrophysics Data System (ADS)

Sauer, Daniela; Al-Sharif, Riyad; Wagner, Stephen; Scarciglia, Fabio; Deffontaines, Benoît; Benvenuti, Marco; Carnicelli, Stefano; Brückner, Helmut

2015-04-01

A sequence of Middle and Late Pleistocene raised marine terraces stretches along the Gulf of Taranto, S Italy, for more than 65 km from Rocca Imperiale, Calabria, in the SW to Taranto, Apulia, in the NE, in an approximately 25 km wide belt. The terraces formed as a result of the interplay between sea-level fluctuations and regional tectonic uplift over a time-span of ca. 780 ka. They were selected for establishing a soil chronosequence, in order to analyse rates of soil-forming processes in the central Mediterranean region. Indeed, several general trends of soil formation with terrace age were identified. For example, soil thickness and Fed/Fet ratios increase, while the weathering ratio (Ca+Mg+K+Na)/Al decreases with assumed terrace age. These changes could be best described by power functions (R2 = 0.88 for soil thickness, R2 = 0.87 for Fed/Fet, and R2 = 0.96 for (Ca+Mg+K+Na)/Al). However, closer examination revealed that the soils did not simply form in the marine gravel bodies but in various kinds of sediments. The development of the landscape along the Gulf of Taranto turned out to be much more complex than previously expected. Sediment-soil successions exposed in several gravel quarries reveal that each terrace, after its original formation, was exposed to changing conditions in terms of climate, vegetation, level of erosion base (related to sea-level oscillations and/or tectonics), and other environmental factors during the Pleistocene and Holocene periods. As a result, it was subject to (i) further geomorphological and sedimentological evolution, including incision, denudation, deposition of alluvial sediments, and accumulation of colluvial deposits, in parts due to natural processes and in parts due to human activity; (ii) various directions and rates of soil development, corresponding to changing environmental conditions during glacial and interglacial periods. In some cases, there is evidence for a period of soil formation in the marine deposits prior to the deposition of the alluvial sediments. For example, a several metres thick marine gravel body, overlain by a layer of alluvial sandy-loamy sediments, is exposed in a gravel quarry on terrace T2 (assumed to have accumulated during MIS 5c). The boundary between the two sediment packages is very sharp and wavy, indicating a period of incision into the gravel body prior to the deposition of the alluvial sediments. Based on these observations, the following chronological sequence of events is assumed for this site: 1) accumulation of the gravel body in a delta environment during MIS 5c; 2) period of soil formation during late MIS 5c, after the surface of the gravel body had fallen dry; 3) incision of creeks, cutting channels into the gravel body as sea level dropped during MIS 5b; 4) sea-level rise during MIS 5a, not reaching the same level as during MIS 5c due to progressing regional uplift in the meantime; wave action of the MIS 5a sea removed part of the MIS 5c gravel body and cut a cliff into it, thus shaping the seaward edge of terrace T2; 5) accumulation of alluvial deposits in the previously incised channels and on top of the erosional gravel-body surface during MIS 5a because of the raised erosion base level; 6) incorporation of sandy sediments from the near-by MIS 5a beach, possibly with some contribution from temporarily dry beds of the nearby torrential rivers, into the alluvial deposits. Similarly complex sediment successions can be observed in several exposures. In addition, in some locations up to several metres of loess-like sediments are exposed. They probably accumulated during glacial periods, being blown out from the wide, temporarily dry river beds and from the exposed shelf. These observations led to a more differentiated reconstruction of the evolution of the landscape and soils in the Metaponto area.

Geospatial risk assessment and trace element concentration in reef associated sediments, northern part of Gulf of Mannar biosphere reserve, Southeast Coast of India.

PubMed

Krishnakumar, S; Ramasamy, S; Simon Peter, T; Godson, Prince S; Chandrasekar, N; Magesh, N S

2017-12-15

Fifty two surface sediments were collected from the northern part of the Gulf of Mannar biosphere reserve to assess the geospatial risk of sediments. We found that distribution of organic matter and CaCO 3 distributions were locally controlled by the mangrove litters and fragmented coral debris. In addition, Fe and Mn concentrations in the marine sediments were probably supplied through the riverine input and natural processes. The Geo-accumulation of elements fall under the uncontaminated category except Pb. Lead show a wide range of contamination from uncontaminated-moderately contaminated to extremely contaminated category. The sediment toxicity level of the elements revealed that the majority of the sediments fall under moderately to highly polluted sediments (23.07-28.84%). The grades of potential ecological risk suggest that predominant sediments fall under low to moderate risk category (55.7-32.7%). The accumulation level of trace elements clearly suggests that the coral reef ecosystem is under low to moderate risk. Copyright © 2017 Elsevier Ltd. All rights reserved.

Arsenic enrichment in shelf and coastal sediment of the Brazilian subtropics

NASA Astrophysics Data System (ADS)

Mirlean, N.; Medeanic, S.; Garcia, F. A.; Travassos, M. P.; Baisch, P.

2012-03-01

High levels of As (i.e., above the nationally legislated threshold of 70 mg kg-1) were found in shelf sediment of the Espirito Santo state of Brazil. The elevated content of this metalloid propagated in the sediment to a depth of approximately 1.5 m. The adjacent beach sands and mangrove sediments were also enriched in As. The variation in As levels along the shelf sediment profiles was acompained by calcareous-material distribution, which reflects the paleogeographical circumstances that promote local reef development during the corresponding intervals of sedimentation. Arsenic-rich calcareous bioclast materials migrate to a beach from the surface horizon of nearby shelf sediment, thereby replacing the part of the As that previously entered the marine environment with eroded material from the continent to the littoral zone. The segment of the Brazilian tropical shelf that was studied clearly demonstrated that the As enrichment of the shelf sediment is determined by the exposure of the Barreiras formation on the coast and the development of reefs, which are favorable sites for the settling of bodies of biogenic carbonates.

The role of certain infauna and vascular plants in the mediation of redox reactions in marine sediments

NASA Technical Reports Server (NTRS)

Hines, Mark E.

1992-01-01

The mechanisms by which certain animals and plants affect redox processes in sediments was examined by studying three environments: (1) subtidal sediments dominated by the deposit-feeding polychaete Heteromastus filiformis; (2) a saltmarsh inhabited by the tall form of Spartina alterniflora; and (3) tropical carbonate sediments inhabited by three species of seagrasses. S-35-sulfide production rates were compared to pool sizes of dissolved sulfide and dissolved iron. In all of the sediments studied, rates of sulfide reduction were enhanced by macroorganisms while the rate of turnover of dissolved sulfide increased. The polychaete enhanced microbial activity and redox cycling primarily by subducting particles of organic matter and oxidized iron during sediment reworking. The Spartina species enhanced anaerobic activity by transporting primarily dissolved organic matter and oxidants. Although the final result of both animal and plant activities was the enhancement of sub-surface cycling of sulfur and iron, decreased dissolved sulfide and increased dissolved iron concentrations, the mechanisms which produced these results differed dramatically.

Geological evolution of the Iraqi Mesopotamia Foredeep, inner platform and near surroundings of the Arabian Plate

NASA Astrophysics Data System (ADS)

Sissakian, Varoujan K.

2013-08-01

The Iraqi territory could be divided into four main tectonic zones; each one has its own characteristics concerning type of the rocks, their age, thickness and structural evolution. These four zones are: (1) Inner Platform (stable shelf), (2) Outer Platform (unstable shelf), (3) Shalair Zone (Terrain), and (4) Zagros Suture Zone. The first two zones of the Arabian Plate lack any kind of metamorphism and volcanism. The Iraqi territory is located in the extreme northeastern part of the Arabian Plate, which is colliding with the Eurasian (Iranian) Plate. This collision has developed a foreland basin that includes: (1) Imbricate Zone, (2) High Folded Zone, (3) Low Folded Zone and (4) Mesopotamia Foredeep. The Mesopotamia Foredeep, in Iraq includes the Mesopotamia Plain and the Jazira Plain; it is less tectonically disturbed as compared to the Imbricate, High Folded and Low Folded Zones. Quaternary alluvial sediments of the Tigris and Euphrates Rivers and their tributaries as well as distributaries cover the central and southeastern parts of the Foredeep totally; it is called the Mesopotamian Flood Plain. The extension of the Mesopotamia Plain towards northwest however, is called the Jazira Plain, which is covered by Miocene rocks. The Mesopotamia Foredeep is represented by thick sedimentary sequence, which thickens northwestwards including synrift sediments; especially of Late Cretaceous age, whereas on surface the Quaternary sediments thicken southeastwards. The depth of the basement also changes from 8 km, in the west to 14 km, in the Iraqi-Iranian boarders towards southeast. The anticlinal structures have N-S trend, in the extreme southern part of the Mesopotamia Foredeep and extends northwards until the Latitude 32°N, within the Jazira Plain, there they change their trends to NW-SE, and then to E-W trend. The Mesozoic sequence is almost without any significant break, with increase in thickness from the west to the east, attaining 5 km. The sequence forms the main source and reservoir rocks in the central and southern parts of Iraq. The Cenozoic sequence consists of Paleogene open marine carbonates, which grades upwards into Neogene lagoonal marine; of Early Miocene and evaporitic rocks; of Middle Miocene age, followed by thick molasses of continental clastics that attain 3500 m in thickness; starting from Late Miocene. The Quaternary sediments are very well developed in the Mesopotamia Plain and they thicken southwards to reach about 180 m near Basra city; in the extreme southeastern part of Iraq. The Iraqi Inner Platform (stable shelf) is a part of the Arabian Plate, being less affected by tectonic disturbances; it covers the area due to south and west of the Euphrates River. The main tectonic feature in this zone that had affected on the geology of the area is the Rutbah Uplift; with less extent is the Ga'ara High. The oldest exposed rocks within the Inner Platform belong to Ga'ara Formation of Permian age; it is exposed only in the Ga'ara Depression. The Permian rocks are overlain by Late Triassic rocks; represented by Mulussa and Zor Hauran formations, both of marine carbonates with marl intercalations. The whole Triassic rocks are absent west, north and east of Ga'ara Depression. Jurassic rocks, represented by five sedimentary cycles, overlie the Triassic rocks. Each cycle consists of clastic rocks overlain by carbonates, being all of marine sediments; whereas the last one (Late Jurassic) consists of marine carbonates only. All the five formations are separated from each other by unconformable contacts. Cretaceous rocks, represented by seven sedimentary cycles, overlie the Jurassic rocks. Marine clastics overlain by marine carbonates. Followed upwards (Late Cretaceous) by continental clastics overlain by marine carbonates; then followed by marine carbonates with marl intercalations, and finally by marine clastics overlain by carbonates; representing the last three cycles, respectively. The Paleocene rocks form narrow belt west of the Ga'ara Depression, represented by Early-Late Paleocene phosphatic facies, which is well developed east of Rutbah Uplift and extends eastwards in the Foredeep. Eocene rocks; west of Rutbah Uplift are represented by marine carbonates that has wide aerial coverage in south Iraq. Locally, east of Rutbah Uplift unconformable contacts are recorded between Early, Middle and Late Eocene rocks. During Oligocene, in the eastern margin of the Inner Platform, the Outer Platform was uplifted causing very narrow depositional Oligocene basin. Therefore, very restricted exposures are present in the northern part of the Inner Platform (north of Ga'ara Depression), represented by reef, forereef sediments of some Oligocene formations. The Miocene rocks have no exposures west of Rutbah Uplift, but north and northwestwards are widely exposed represented by Early Miocene of marine carbonates with marl intercalations. Very locally, Early Miocene deltaic clastics and carbonates, are interfingering with the marine carbonates. The last marine open sea sediments, locally with reef, represent the Middle Miocene rocks and fore reef facies that interfingers with evaporates along the northern part of Abu Jir Fault Zone, which is believed to be the reason for the restriction of the closed lagoons; in the area. During Late Miocene, the continental phase started in Iraq due to the closure of the Neo-Tethys and collision of the Sanandaj Zone with the Arabian Plate. The continental sediments consist of fine clastics. The Late Miocene - Middle Pliocene sediments were not deposited in the Inner Platform. The Pliocene-Pleistocene sediments are represented by cyclic sediments of conglomeratic sandstone overlain by fresh water limestone, and by pebbly sandstone. The Quaternary sediments are poorly developed in the Inner Platform. Terraces of Euphrates River and those of main valleys represent pleistocene sediments. Flood plain of the Euphrates River and those of large valleys represent Holocene sediments. Residual soil is developed, widely in the western part of Iraq, within the western marginal part of the Inner Platform.

Spatial variation in sediment-water exchange of phosphorus in Florida Bay: AMP as a model organic compound.

PubMed

Huang, Xiao-Lan; Zhang, Jia-Zhong

2010-10-15

Dissolved organic phosphorus (DOP) has been recognized as dominant components in total dissolved phosphorus (TDP) pools in many coastal waters, and its exchange between sediment and water is an important process in biogeochemical cycle of phosphorus. Adenosine monophosphate (AMP) was employed as a model DOP compound to simulate phosphorus exchange across sediment-water interface in Florida Bay. The sorption data from 40 stations were fitted to a modified Freundlich equation and provided a detailed spatial distribution both of the sediment's zero equilibrium phosphorus concentration (EPC(0-T)) and of the distribution coefficient (K(d-T)) with respect to TDP. The K(d-T) was found to be a function of the index of phosphorus saturation (IPS), a molar ratio of the surface reactive phosphorus to the surface reactive iron oxide content in the sediment, across the entire bay. However, the EPC(0-T) was found to correlate to the contents of phosphorus in the eastern bay only. Sediment in the western bay might act as a source of the phosphorus in the exchange process due to their high EPC(0-T) and low K(d-T), whereas sediments in the eastern bay might act as a sink because of their low EPC(0-T) and high K(d-T). These results strongly support the hypothesis that both phosphorus and iron species in calcareous marine sediments play a critical role in governing the sediment-water exchange of both phosphate and DOP in the coastal and estuarine ecosystems.

Distribution of heavy metals and environmental assessment of surface sediment of typical estuaries in eastern China.

PubMed

Bi, Shipu; Yang, Yuan; Xu, Chengfen; Zhang, Yong; Zhang, Xiaobo; Zhang, Xianrong

2017-08-15

Estuary sediment is a major pollutant enrichment medium and is an important biological habitat. This sediment has attracted the attention of the marine environmental scientists because it is a more stable and effective medium than water for monitoring regional environmental quality conditions and trends. Based on a large amount of measurement data, we analyzed the concentrations, distribution, and sources of seven heavy metals (As, Cd, Cr, Cu, Hg, Pb, and Zn) in the surface sediment of typical estuaries that empty into the sea in eastern China: the Liaohe River Estuary, Yellow River Estuary, Yangtze River Estuary, Minjiang River Estuary, and Pearl River Estuary. The heavy metal concentrations in the sediments vary considerably from one estuary to the next. The Liaohe River Estuary sediment contains elevated levels of Cd, Hg, and Zn. The Yellow River Estuary sediment contains elevated levels of As. The sediments in the Yangtze River and Minjiang River estuaries contain elevated levels of Cd and Cu and of Pb and Zn, respectively. The sediment in the Pearl River Estuary contains elevated levels of all seven heavy metals. We used the Nemerow index method to assess the environment quality. The heavy metal pollution in the Liaohe River and Pearl River estuaries is more severe than that in the other estuaries. Additional work indicates that the heavy metal pollution in the Liaohe River and Pearl River estuaries is caused mainly by human activity. Copyright © 2017. Published by Elsevier Ltd.

Redox processes as revealed by voltammetry in the surface sediments of the Gotland Basin, Baltic Sea

NASA Astrophysics Data System (ADS)

Yücel, Mustafa; Dale, Andy; Sommer, Stefan; Pfannkuche, Olaf

2014-05-01

Sulfur cycling in marine sediments undergoes dramatic changes with changing redox conditions of the overlying waters. The upper sediments of the anoxic Gotland Basin, central Baltic Sea represent a dynamic redox environment with extensive mats of sulfide oxidizing bacteria covering the seafloor beneath the chemocline. In order to investigate sulfur redox cycling at the sediment-water interface, sediment cores were sampled over a transect covering 65 - 174 m water depth in August-September 2013. High resolution (0.25 mm minimum) vertical microprofiles of electroactive redox species including dissolved sulfide and iron were obtained with solid state Au-Hg voltammetric microelectrodes. This approach enabled a fine-scale comparison of porewater profiles across the basin. The steepest sulfide gradients (i.e. the highest sulfide consumption) occurred within the upper 10 mm in sediments covered by surficial mats (2.10 to 3.08 mmol m-2 day-1). In sediments under permanently anoxic waters (>140m), voltammetric signals for Fe(II) and aqueous FeS were detected below a subsurface maximum in dissolved sulfide, indicating a Fe flux originating from older, deeper sedimentary layers. Our results point to a unique sulfur cycling in the Gotland basin seafloor where sulfide accumulation is moderated by sulfide oxidation at the sediment surface and by FeS precipitation in deeper sediment layers. These processes may play an important role in minimizing benthic sulfide fluxes to bottom waters around the major basins of the Baltic Sea.

Paired measurements of K and Mg isotopes and clay authigenesis in marine sediments

NASA Astrophysics Data System (ADS)

Santiago Ramos, D. P.; Dunlea, A. G.; Higgins, J. A.

2016-12-01

Despite its importance as a major sink for seawater K and Mg, estimates of clay authigenesis in marine sediments remain poorly constrained. Previous work on Mg isotope fractionation during clay formation has revealed a preferential uptake of 26Mg, yielding authigenic clay products with potentially distinct δ26Mg compared to the detrital component. In a similar manner, we aim to quantify the K isotope fractionation during authigenic clay formation and to use paired δ26Mg and δ41K measurements as proxies for the identification and quantification of authigenic clays in shallow and deep marine sedimentary systems. To better understand the behavior of paired Mg and K isotopes during authigenic clay formation in marine sediments, we measured δ26Mg and δ41K values of pore-fluids and sediments from ODP/IODP sites 1052, U1395, U1403 and U1366. We find that while pore-fluid K concentrations at sites 1052, U1395 and U1403 all decline with depth, δ41K profiles differ significantly. These differences might be a result of a complex interplay between clay authigenesis, sedimentation rate, and fractionation of K isotopes during diffusion. Results from 1-D diffusion-advection-reaction models suggest that, in contrast to Mg, diffusion may play an important role in determining the overall K isotope fractionation during clay authigenesis in sites with low-sedimentation rates. Sites with high sedimentation rates may act as close systems where diffusion is negligible. In such cases, K uptake can be modeled as a Rayleigh distillation process and K isotope fractionation can be estimated. Measurements of δ26Mg and δ41K of pore-fluids from site U1395 and bulk sediments from U1366 suggest that paired measurements of these isotopic systems in siliciclastic marine sediments can provide new insights into rates of marine clay authigenesis, a globally important but understudied component of many geochemical cycles.

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

USGS Publications Warehouse

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.

Shallow geology, sea-floor texture, and physiographic zones of Buzzards Bay, Massachusetts

USGS Publications Warehouse

Foster, David S.; Baldwin, Wayne E.; Barnhardt, Walter A.; Schwab, William C.; Ackerman, Seth D.; Andrews, Brian D.; Pendleton, Elizabeth A.

2015-01-07

Geologic, sediment texture, and physiographic zone maps characterize the sea floor of Buzzards Bay, Massachusetts. These maps were derived from interpretations of seismic-reflection profiles, high-resolution bathymetry, acoustic-backscatter intensity, bottom photographs, and surficial sediment samples. The interpretation of the seismic stratigraphy and mapping of glacial and Holocene marine units provided a foundation on which the surficial maps were created. This mapping is a result of a collaborative effort between the U.S. Geological Survey and the Massachusetts Office of Coastal Zone Management to characterize the surface and subsurface geologic framework offshore of Massachusetts.

Three depositional states and sedimentary processes of the western Taiwan foreland basin system

NASA Astrophysics Data System (ADS)

Lin, Yi-Jung; Wu, Pei-Jen; Yu, Ho-Shing

2010-05-01

The western Taiwan foreland basin formed during the Early Pliocene as the flexural response to the loading of Taiwan orogen on the Eurasian plate. What makes Taiwan interesting is the oblique collision, which allows the foreland basin to be seen at different stages in its evolution at the present day. Due to oblique arc-continent collision from north to south, the western Taiwan foreland basin has evolved into three distinct subbasins: an over-filled basin proximal to the Taiwan orogen, mainly distributed in the Western Foothills and Coastal Plain provinces, a filled basin occupying the shallow Taiwan Strait continental shelf west of the Taiwan orogen and an under-filled basin distal to the Taiwan orogen in the deep marine Kaoping Slope offshore southwest Taiwan, respectively. The over-filled depositional phase is dominated by fluvial environments across the structurally controlled piggy-back basins. The filled depositional state in the Taiwan Strait is characterized by shallow marine environments and is filled by Pliocene-Quaternary sediments up to 4,000 m thick derived from the Taiwan orogen with an asymmetrical and wedge-shaped cross section. The under-filled depositional state is characteristic of deep marine environments in the wedge-top basins accompanied by active structures of thrust faults and mud diapers. Sediments derived from the Taiwan orogen have progressively filled the western Taiwan foreland basin across and along the orogen. Sediment dispersal model suggests that orogenic sediments derived from oblique dischronous collisional highlands are transported in two different ways. Transport of fluvial and shallow marine sediments is perpendicular to hill-slope and across-strike in the fluvial and shallow marine environments proximal to the orogen. Fine-grained sediments mainly longitudinally transported into the deep marine environments distal to the orogen. The present sedimentary processes in the over-filled basin on land are dominated by fluvial processes of small mountainous rivers. Tidal currents are prevalent in the filled basin in Taiwan Strait, transporting shelf sands and forming sand ridges. The deep marine under-filled basin are dominated by down-slope mass wasting processes, eroding slope strata and transporting sediments to the basin floor. In addition, many submarine canyons on the continental slope offshore southwest Taiwan serve as major sediment pathways, delivering shallow marine sediments to the basin floor.

Radioecologycal study of {sup 239/240}Pu in Bangka Island and Muria Peninsula: Determination of {sup 239/240}Pu in marine sediment and seawater as part of baseline data collecting for sitting of candidates of first Indonesia NPP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suseno, Heny, E-mail: henis@batan.go.id; Wisnubroto, Djarot S.

Radioisotope Pu-239/240 are alpha emitting nuclides important indicators of radioactive contamination of the marine environment. Global fallout is the main source of plutonium in the marine environment. There are very limited study on {sup 239/240}Pu in Indonesia coastal environments. The data of this radioisotopes is needed for baseline data of nuclear power plant (NPP) site candidates both in Bangka Island and Muria Peninsula. Bottom sediments play an important role in radioecological studies of the marine environment because a large proportion of radioactive substances entering the sea is adsorbed over time onto suspended particulate matter and deposited in sediments. Plutonium ismore » particle reactive and deposited in marine sediment. Radioisotope {sup 239/240}Pu was determinated by alpha spectrometry after radiochemical procedure that was performed in both water and marine sediment from Bangka Island and Muria Peninsula. The sediment baseline of concentration {sup 239/240}Pu in Bangka Island and Muria Peninsula were range from 0.013 to 0.021 Bq.kg{sup −1} and 0.018 to 0.024 Bq.kg{sup −1} respectively. The water baseline concentration this isotope were range from 2.73 to 4.05 mBq.m{sup −3} and 2.98 to 4.50 mBq.m{sup −3}.« less

Faulting of gas-hydrate-bearing marine sediments - contribution to permeability

USGS Publications Warehouse

Dillon, William P.; Holbrook, W.S.; Drury, Rebecca; Gettrust, Joseph; Hutchinson, Deborah; Booth, James; Taylor, Michael

1997-01-01

Extensive faulting is observed in sediments containing high concentrations of methane hydrate off the southeastern coast of the United States. Faults that break the sea floor show evidence of both extension and shortening; mud diapirs are also present. The zone of recent faulting apparently extends from the ocean floor down to the base of gas-hydrate stability. We infer that the faulting resulted from excess pore pressure in gas trapped beneath the gas hydrate-beating layer and/or weakening and mobilization of sediments in the region just below the gas-hydrate stability zone. In addition to the zone of surface faults, we identified two buried zones of faulting, that may have similar origins. Subsurface faulted zones appear to act as gas traps.

Phosphorus sorption on marine carbonate sediment: phosphonate as model organic compounds.

PubMed

Huang, Xiao-Lan; Zhang, Jia-Zhong

2011-11-01

Organophosphonate, characterized by the presence of a stable, covalent, carbon to phosphorus (C-P) bond, is a group of synthetic or biogenic organophosphorus compounds. The fate of these organic phosphorus compounds in the environment is not well studied. This study presents the first investigation on the sorption of phosphorus (P) in the presence of two model phosphonate compounds, 2-aminothylphosphonoic acid (2-AEP) and phosphonoformic acid (PFA), on marine carbonate sediments. In contrast to other organic P compounds, no significant inorganic phosphate exchange was observed in seawater. P was found to adsorb on the sediment only in the presence of PFA, not 2-AEP. This indicated that sorption of P from phosphonate on marine sediment was compound specific. Compared with inorganic phosphate sorption on the same sediments, P sorption from organic phosphorus is much less in the marine environment. Further study is needed to understand the potential role of the organophosphonate compounds in biogeochemical cycle of phosphorus in the environment. Copyright © 2011 Elsevier Ltd. All rights reserved.

Ecological risk assessment of heavy metals in surface seawater and sediment near the outlet of a zinc factory in Huludao City, Liaoning Province, China

NASA Astrophysics Data System (ADS)

Feng, Yongliang; Chen, Yanzhen; Wang, Jing; Gong, Yufeng; Liu, Xigang; Mu, Gang; Tian, Hua

2016-11-01

At present, the methods widely applied to assess ecological risk of heavy metals are essentially single-point estimates in which exposure and toxicity data cannot be fully used and probabilities of adverse biological eff ects cannot be achieved. In this study, based on investigation of concentrations of six heavy metals (As, Hg, Pb, Cd, Cu, and Zn) in the surface seawater and sediment near the outlet of a zinc factory, located in Huludao City, Liaoning Province, China, a tiered approach consisting of several probabilistic options was used to refine ecological risk assessment for the individuals. A mixture of various heavy metals was detected in the surface seawater, and potential ecological risk index (PERI) was adopted to assess the potential ecological risk of heavy metals in the surface sediment. The results from all levels of aquatic ecological risk assessment in the tiered framework, ranging from comparison of single eff ects and exposure values to the use of distribution-based Hazard Quotient obtained through Monte Carlo simulation, are consistent with each other. Briefly, aquatic Zn and Cu posed a clear ecological risk, while Cd, Pb, Hg, and As in the water column posed potential risk. As expected, combined ecological risk of heavy metal mixture in the surface seawater was proved significantly higher than the risk caused by any individual heavy metal, calculated using the concept of total equivalent concentration. According to PERI, the severity of pollution by the six heavy metals in the surface sediment decreased in the following sequence: Cd>Hg>As>Pb>Cu>Zn, and the total heavy metals in the sediment posed a very high risk to the marine environment. This study provides a useful mathematical framework for ecological risk assessment of heavy metals.

Selenium in irrigated agricultural areas of the western United States

USGS Publications Warehouse

Nolan, B.T.; Clark, M.L.

1997-01-01

A logistic regression model was developed to predict the likelihood that Se exceeds the USEPA chronic criterion for aquatic life (5 ??g/L) in irrigated agricultural areas of the western USA. Preliminary analysis of explanatory variables used in the model indicated that surface-water Se concentration increased with increasing dissolved solids (DS) concentration and with the presence of Upper Cretaceous, mainly marine sediment. The presence or absence of Cretaceous sediment was the major variable affecting Se concentration in surface-water samples from the National Irrigation Water Quality Program. Median Se concentration was 14 ??g/L in samples from areas underlain by Cretaceous sediments and < 1 ??g/L in samples from areas underlain by non-Cretaceous sediments. Wilcoxon rank sum tests indicated that elevated Se concentrations in samples from areas with Cretaceous sediments, irrigated areas, and from closed lakes and ponds were statistically significant. Spearman correlations indicated that Se was positively correlated with a binary geology variable (0.64) and DS (0.45). Logistic regression models indicated that the concentration of Se in surface water was almost certain to exceed the Environmental Protection Agency aquatic-life chronic criterion of 5 ??g/L when DS was greater than 3000 mg/L in areas with Cretaceous sediments. The 'best' logistic regression model correctly predicted Se exceedances and nonexceedances 84.4% of the time, and model sensitivity was 80.7%. A regional map of Cretaceous sediment showed the location of potential problem areas. The map and logistic regression model are tools that can be used to determine the potential for Se contamination of irrigated agricultural areas in the western USA.

Geochemical evidence for enhanced preservation of organic matter in the oxygen minimum zone of the continental margin of northern California during the Late Pleistocene

USGS Publications Warehouse

Dean, Walter E.; Gardner, James V.; Anderson, Roger Y.

1994-01-01

The present upper water mass of the northeastern Pacific Ocean off California has a well-developed oxygen minimum zone between 600 and 1200 m wherein concentrations of dissolved oxygen are less than 0.5 mL/L. Even at such low concentrations of dissolved oxygen, benthic burrowing organisms are abundant enough to thoroughly bioturbate the surface and near-surface sediments. These macro organisms, together with micro organisms, also consume large quantities of organic carbon produced by large seasonal stocks of plankton in the overlying surface waters, which are supported by high concentrations of nutrients within the California Current upwelling system. In contrast to modern conditions of bioturbation, laminated sediments are preserved in upper Pleistocene sections of cores collected on the continental slope at water depths within the present oxygen minimum zone from at least as far north as the California-Oregon border and as far south as Point Conception. Comparison of sediment components in the laminae with those delivered to sediment traps as pelagic marine “snow” demonstrates that the dark-light lamination couplets are indeed annual (varves). These upper Pleistocene varved sediments contain more abundant lipid-rich “sapropelic” (type II) organic matter than the overlying bioturbated, oxidized Holocene sediments. The baseline of stable carbon isotopic composition of the organic matter in these slope cores does not change with time, indicating that the higher concentrations of type II organic matter in the varved sediments represent better preservation of organic matter rather than any change in the source of organic matter.

Sediment property changes in response to the glacial activity on the continental slope to the eastern side of Pennell-Iselin Bank in the Ross Sea, Antarctica

NASA Astrophysics Data System (ADS)

Ha, Sangbeom; Khim, Boo-Keun; Colizza, Ester; Marci, Patrizia; Sagnotti, Leonardo; Caricchi, Chiara; Langone, Leonardo; Giglio, Federico; Kuhn, Gerhard

2017-04-01

High latitude marine environments including the Antarctic continental margin have sensitively responded to the climate change, and the Ross Sea is one of these examples. Subglacial marine sedimentary changes have been studied extensively in the continental shelf areas of the Ross Sea to understand the growth and retreat of glaciers in response to the glacial-interglacial changes. However, the continental slope areas of the Ross Sea have not been investigated comparatively less. Thus, in order to comprehend the glaciomarine sedimentation change on the continental slope of the Ross Sea, 3 gravity cores (GC1, GC2, GC3) and 3 box cores (BC1, BC2, BC3) were collected from 3 sites (RS14-C1, C2, C3 by decreasing water depth), respectively, across the continental slope to the eastern side of the Pennell-Iselin Bank during XXIX PNRA (Rosslope II) cruise in 2014. A variety of sedimentological (grain size, magnetic susceptibility, XRF) and geochemical (biogenic opal, total organic carbon, CaCO3, δ13C of organic matter) properties were analyzed along with AMS 14C dating of bulk sediments. All core sediments consist of mostly hemipelagic sandy clay or silty clay with scattered IRD (Ice-Rafted Debris). Sediment color of three cores changes consistently downward from brown to gray with some alternations in core GC1. Based on the basic sediment properties such as sediment color, grain size, and magnetic susceptibility, sediment lithology was decided to divide Unit A and Unit B, both of which were further divided into two subunits. Despite old carbon effect, AMS 14C dates confirm that Unit A belongs to the Holocene and Unit B covers the deglacial to last glacial period at the top of cores. Unit A is characterized by low TOC, low CaCO3, low biogenic opal content and low C/N ratios, whereas Unit B is characterized by high TOC, high CaCO3, moderate to high biogenic opal content and high C/N ratios. Consequently, Unit A represents the modern and interglacial sediments deposited mainly by the suspension settling of biogenic particles in the open marine condition. In contrast, because Unit B shows higher TOC, CaCO3 content and C/N ratios, these sediments might be supplied by the lateral melt-water plume or distal part of debris flow originated from the front of grounding ice in the subglacial continental shelf under the ice shelf and during the glacial or post-glacial period. Thus, Unit B contains mostly reworked and eroded continental shelf sediments and IRDs. In addition, because the peaks of biogenic opal and TOC contents at Site C1 are distinctly higher than Sites C2 and C3, surface water production occurred under seasonally open marine condition at the deeper Site C1. In conclusion, the influence of subglacial continental shelf sedimentation in terms of melt-water transport and/or distal stage of debris flow was limited as far as to Site C2 during the deglacial and glacial period. However, such depositional effect was insignificant, but the seasonal open marine condition was recognized, at the deeper Site C1 in the continental slope of the Ross Sea.

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

PubMed

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 (C org ) 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 C org 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.

Archaeal community diversity and abundance changes along a natural salinity gradient in estuarine sediments.

PubMed

Webster, Gordon; O'Sullivan, Louise A; Meng, Yiyu; Williams, Angharad S; Sass, Andrea M; Watkins, Andrew J; Parkes, R John; Weightman, Andrew J

2015-02-01

Archaea are widespread in marine sediments, but their occurrence and relationship with natural salinity gradients in estuarine sediments is not well understood. This study investigated the abundance and diversity of Archaea in sediments at three sites [Brightlingsea (BR), Alresford (AR) and Hythe (HY)] along the Colne Estuary, using quantitative real-time PCR (qPCR) of 16S rRNA genes, DNA hybridization, Archaea 16S rRNA and mcrA gene phylogenetic analyses. Total archaeal 16S rRNA abundance in sediments were higher in the low-salinity brackish sediments from HY (2-8 × 10(7) 16S rRNA gene copies cm(-3)) than the high-salinity marine sites from BR and AR (2 × 10(4)-2 × 10(7) and 4 × 10(6)-2 × 10(7) 16S rRNA gene copies cm(-3), respectively), although as a proportion of the total prokaryotes Archaea were higher at BR than at AR or HY. Phylogenetic analysis showed that members of the 'Bathyarchaeota' (MCG), Thaumarchaeota and methanogenic Euryarchaeota were the dominant groups of Archaea. The composition of Thaumarchaeota varied with salinity, as only 'marine' group I.1a was present in marine sediments (BR). Methanogen 16S rRNA genes from low-salinity sediments at HY were dominated by acetotrophic Methanosaeta and putatively hydrogentrophic Methanomicrobiales, whereas the marine site (BR) was dominated by mcrA genes belonging to methylotrophic Methanococcoides, versatile Methanosarcina and methanotrophic ANME-2a. Overall, the results indicate that salinity and associated factors play a role in controlling diversity and distribution of Archaea in estuarine sediments. © The Author 2014. Published by Oxford University Press on behalf of Federation of European Microbiological Society.

Global rates of marine sulfate reduction and implications for sub-sea-floor metabolic activities

NASA Astrophysics Data System (ADS)

Bowles, Marshall W.; Mogollón, José M.; Kasten, Sabine; Zabel, Matthias; Hinrichs, Kai-Uwe

2014-05-01

Sulfate reduction is a globally important redox process in marine sediments, yet global rates are poorly quantified. We developed an artificial neural network trained with 199 sulfate profiles, constrained with geomorphological and geochemical maps to estimate global sulfate-reduction rate distributions. Globally, 11.3 teramoles of sulfate are reduced yearly (~15% of previous estimates), accounting for the oxidation of 12 to 29% of the organic carbon flux to the sea floor. Combined with global cell distributions in marine sediments, these results indicate a strong contrast in sub-sea-floor prokaryote habitats: In continental margins, global cell numbers in sulfate-depleted sediment exceed those in the overlying sulfate-bearing sediment by one order of magnitude, whereas in the abyss, most life occurs in oxic and/or sulfate-reducing sediments.

Integrated biostratigraphic and sequence stratigraphic framework for Upper Cretaceous strata of the eastern Gulf Coastal Plain, USA

USGS Publications Warehouse

Mancini, E.A.; Puckett, T.M.; Tew, B.H.

1996-01-01

Upper Cretaceous (Santonian-Maastrichtian stages) strata of the eastern US Gulf Coastal Plain represent a relatively complete section of marine to nonmarine mixed siliciclastic and carbonate sediments. This section includes three depositional sequences which display characteristic systems tracts and distinct physical defining surfaces. The marine lithofacies are rich in calcareous nannoplankton and planktonic foraminifera which can be used for biostratigraphic zonation. Integration of this zonation with the lithostratigraphy and sequence stratigraphy of these strata results in a framework that can be used for local and regional intrabasin correlation and potentially for global interbasin correlation. Only the synchronous maximum flooding surfaces of these depositional sequences, however, have chronostratigraphic significance. The sequence boundaries and initial flooding surfaces are diachronous, and their use for correlation can produce conflicting results. The availability of high resolution biostratigraphy is critical for global correlation of depositional sequences. ?? 1996 Academic Press Limited.

Structural characteristics of fulvic acids from Continental Shelf sediments

USGS Publications Warehouse

Hatcher, P.G.; Breger, I.A.; Mattingly, M.A.

1980-01-01

Fulvic acids are those components of soil organic matter that remain soluble after a dilute alkaline extract of the soil is acidified to pH 2 (refs 1, 2). This extraction procedure has been applied to marine sediments, and the organic compounds so recovered have been called marine sedimentary fulvic acids. These fulvic acids are thought to form more complex humic substances in marine sediments by condensation reactions3. However, the chemical structural compositions of marine fulvic acids have not been defined sufficiently to allow this precursor relationship to be made. Here NMR spectroscopy is used to identify more clearly the chemical structural components of some marine sedimentary fulvic acids, thus enabling a more useful examination of their relationship to more complex humic substances. ?? 1980 Nature Publishing Group.

Bioturbation determines the response of benthic ammonia-oxidizing microorganisms to ocean acidification

PubMed Central

Laverock, B.; Kitidis, V.; Tait, K.; Gilbert, J. A.; Osborn, A. M.; Widdicombe, S.

2013-01-01

Ocean acidification (OA), caused by the dissolution of increasing concentrations of atmospheric carbon dioxide (CO2) in seawater, is projected to cause significant changes to marine ecology and biogeochemistry. Potential impacts on the microbially driven cycling of nitrogen are of particular concern. Specifically, under seawater pH levels approximating future OA scenarios, rates of ammonia oxidation (the rate-limiting first step of the nitrification pathway) have been shown to dramatically decrease in seawater, but not in underlying sediments. However, no prior study has considered the interactive effects of microbial ammonia oxidation and macrofaunal bioturbation activity, which can enhance nitrogen transformation rates. Using experimental mesocosms, we investigated the responses to OA of ammonia oxidizing microorganisms inhabiting surface sediments and sediments within burrow walls of the mud shrimp Upogebia deltaura. Seawater was acidified to one of four target pH values (pHT 7.90, 7.70, 7.35 and 6.80) in comparison with a control (pHT 8.10). At pHT 8.10, ammonia oxidation rates in burrow wall sediments were, on average, fivefold greater than in surface sediments. However, at all acidified pH values (pH ≤ 7.90), ammonia oxidation rates in burrow sediments were significantly inhibited (by 79–97%; p < 0.01), whereas rates in surface sediments were unaffected. Both bacterial and archaeal abundances increased significantly as pHT declined; by contrast, relative abundances of bacterial and archaeal ammonia oxidation (amoA) genes did not vary. This research suggests that OA could cause substantial reductions in total benthic ammonia oxidation rates in coastal bioturbated sediments, leading to corresponding changes in coupled nitrogen cycling between the benthic and pelagic realms. PMID:23980243

Oceanographic effects of the 1992 Point Loma sewage pipe spill

DOE Office of Scientific and Technical Information (OSTI.GOV)

Casey, R.; Ciccateri, A.; Dougherty, K.

Early in early 1992, 180 million gallons of advanced primarily treated sewage emptied into 10 meters of water from the broken Point Loma sewage pipe, San Diego. For about two months a sewage boil about the size of a football field existed at the surface and within the Point Loma kelp bed. Sampling and observations taken during the spill indicated the surface waters at the spill site were grayish and smelling of sewage. The sewage water had mixed with the marine waters reducing salinity to about one-half normal (or 15 ppt.). The sediment load of the sewage coated the bladesmore » of the giant kelp and the kelp was limp and withdrawn from the surface. At the site of the main boil the kelp appeared to have dropped to the bottom. Sediments on the bottom in the boil area were mainly coarse sands as compared to the surrounding sandy-muds. Preliminary results using laboratory analysis suggest: one month into the spill no infauna were observed in the sediments or planktons in the water of the boil area, but were in the surrounding sediments and water; the observed phytoplankton were dominated by dinoflagellates and suggested red tide conditions surrounding the boil. The site has been monitored monthly since the spill to observe further impact and recovery.« less

Microplastics in the surface sediments from the Beijiang River littoral zone: Composition, abundance, surface textures and interaction with heavy metals.

PubMed

Wang, Jundong; Peng, Jinping; Tan, Zhi; Gao, Yifan; Zhan, Zhiwei; Chen, Qiuqiang; Cai, Liqi

2017-03-01

While large quantities of studies on microplastics in the marine environment have been widely carried out, few were available in the freshwater environment. The occurrence and characteristics, including composition, abundance, surface texture and interaction with heavy metals, of microplastics in the surface sediments from Beijiang River littoral zone were investigated. The concentrations of microplastics ranged from 178 ± 69 to 544 ± 107 items/kg sediment. SEM images illustrated that pits, fractures, flakes and adhering particles were the common patterns of degradation. Chemical weathering of microplastics was also observed and confirmed by μ-FTIR. EDS spectra displayed difference in the elemental types of metals on the different surface sites of individual microplastic, indicating that some metals carried by microplastics were not inherent but were derived from the environment. The content of metals (Ni, Cd, Pb, Cu, Zn and Ti) in microplastics after ultrasonic cleaning has been analyzed by ICP-MS. Based on data from the long-term sorption of metals by microplastics and a comparison of metal burden between microplastics, macroplastics and fresh plastic products, we suggested that the majority of heavy metals carried by microplastics were derived from inherent load. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characteristics of Holocene sediments in the Gunsan Basin, central Yellow Sea

NASA Astrophysics Data System (ADS)

Woo, H. J.; Huh, S.; Jeong, K. S.; Lee, J. H.; Ham, A.; Kang, J.

2016-12-01

The Gunsan Basin, in the eastern part of the South Yellow Sea Basin, is filled by terrestrial sedimentary rocks, maximally up to 8 km deep on the basement of metamorphic rocks that constitutes the Yangtze Platform. The uppermost sedimentary layer (generally less than 1 km) appears to have formed experiencing the repeated marine environments since the middle Miocene. This study is to investigate the characteristics of Holocene sediments in the Gunsan Basin, based on interpretation of core sediments and high-resolution shallow (Sparker and Chirp) seismic profiles. The surface sediments in the basin consist of sand (56.6% on the average), silt (18.4%), and clay (25.0%) with a mean grain size of 1.5 to 7.8 Ø. Sand is prevalent (63.8 to 98.3%) in and around the Yellow Sea Trough lying in the eastern part of the basin. The sandy sediments are regarded as relict sediments deposited in the last glacial maximum (LGM). The sedimentary environments are classified, based on the acoustic and morphological characters of high-resolution shallow (Sparker and Chirp) seismic profiles, into mud zone, deformed zone, and sand ridges with sand waves zone from the west to the east in the Gunsan Basin. The deformed zone in the central Yellow Sea is a mixing area of sediments derived from China and Korea, where there are a number of paleochannels and erosional surfaces in the direction of northwest-southeast. The deformed zone represents non-deposition or erosion in the central Yellow Sea during the Holocene. Tidal sand ridges and sand waves are well developed along the coast of Korea. Modern sand ridges are generally moving in the northeast-southwest direction, which coincide with dominant tidal current direction. Fifteen piston cores were collected in the basin to investigate the general geological characters of the marine sedimentary sequence. In comparison with three cores in the southern basin, the sand contents tend to increase in the direction of east. 14C dates from three cores near border of Exclusive Economic Zone (EEZ) of Korea reveal that Holocene sediments have accumulated at the rate 6-18 cm/ka. The mud sediments sequentially change sandy mud to mud after the sea-level rise. In the Gunsan Basin, paleochannels played an important role in sedimentary processes during low sea-level periods of Quaternary.

Microplastics in Arctic polar waters: the first reported values of particles in surface and sub-surface samples

PubMed Central

Lusher, Amy L.; Tirelli, Valentina; O’Connor, Ian; Officer, Rick

2015-01-01

Plastic, as a form of marine litter, is found in varying quantities and sizes around the globe from surface waters to deep-sea sediments. Identifying patterns of microplastic distribution will benefit an understanding of the scale of their potential effect on the environment and organisms. As sea ice extent is reducing in the Arctic, heightened shipping and fishing activity may increase marine pollution in the area. Microplastics may enter the region following ocean transport and local input, although baseline contamination measurements are still required. Here we present the first study of microplastics in Arctic waters, south and southwest of Svalbard, Norway. Microplastics were found in surface (top 16 cm) and sub-surface (6 m depth) samples using two independent techniques. Origins and pathways bringing microplastic to the Arctic remain unclear. Particle composition (95% fibres) suggests they may either result from the breakdown of larger items (transported over large distances by prevailing currents, or derived from local vessel activity), or input in sewage and wastewater from coastal areas. Concurrent observations of high zooplankton abundance suggest a high probability for marine biota to encounter microplastics and a potential for trophic interactions. Further research is required to understand the effects of microplastic-biota interaction within this productive environment. PMID:26446348

Microplastics in Arctic polar waters: the first reported values of particles in surface and sub-surface samples

NASA Astrophysics Data System (ADS)

Lusher, Amy L.; Tirelli, Valentina; O'Connor, Ian; Officer, Rick

2015-10-01

Plastic, as a form of marine litter, is found in varying quantities and sizes around the globe from surface waters to deep-sea sediments. Identifying patterns of microplastic distribution will benefit an understanding of the scale of their potential effect on the environment and organisms. As sea ice extent is reducing in the Arctic, heightened shipping and fishing activity may increase marine pollution in the area. Microplastics may enter the region following ocean transport and local input, although baseline contamination measurements are still required. Here we present the first study of microplastics in Arctic waters, south and southwest of Svalbard, Norway. Microplastics were found in surface (top 16 cm) and sub-surface (6 m depth) samples using two independent techniques. Origins and pathways bringing microplastic to the Arctic remain unclear. Particle composition (95% fibres) suggests they may either result from the breakdown of larger items (transported over large distances by prevailing currents, or derived from local vessel activity), or input in sewage and wastewater from coastal areas. Concurrent observations of high zooplankton abundance suggest a high probability for marine biota to encounter microplastics and a potential for trophic interactions. Further research is required to understand the effects of microplastic-biota interaction within this productive environment.

Microplastics in Arctic polar waters: the first reported values of particles in surface and sub-surface samples.

PubMed

Lusher, Amy L; Tirelli, Valentina; O'Connor, Ian; Officer, Rick

2015-10-08

Plastic, as a form of marine litter, is found in varying quantities and sizes around the globe from surface waters to deep-sea sediments. Identifying patterns of microplastic distribution will benefit an understanding of the scale of their potential effect on the environment and organisms. As sea ice extent is reducing in the Arctic, heightened shipping and fishing activity may increase marine pollution in the area. Microplastics may enter the region following ocean transport and local input, although baseline contamination measurements are still required. Here we present the first study of microplastics in Arctic waters, south and southwest of Svalbard, Norway. Microplastics were found in surface (top 16 cm) and sub-surface (6 m depth) samples using two independent techniques. Origins and pathways bringing microplastic to the Arctic remain unclear. Particle composition (95% fibres) suggests they may either result from the breakdown of larger items (transported over large distances by prevailing currents, or derived from local vessel activity), or input in sewage and wastewater from coastal areas. Concurrent observations of high zooplankton abundance suggest a high probability for marine biota to encounter microplastics and a potential for trophic interactions. Further research is required to understand the effects of microplastic-biota interaction within this productive environment.

Distribution, sources and contamination assessment of heavy metals in surface sediments of the South Yellow Sea and northern part of the East China Sea.

PubMed

Lu, Jian; Li, Anchun; Huang, Peng

2017-11-15

Surface sediment samples collected from the South Yellow Sea and northern part of the East China Sea during spring and autumn, respectively, were analyzed for grain size, aluminum, and heavy metals (Cr, Ni, Cu, Zn, and Pb) to evaluate heavy metal levels and the contamination status. The results showed that all of the heavy metal concentrations met the standard criteria of the Chinese National Standard Criteria for Marine Sediment Quality. Both the EFs and a multivariate analysis (PCA) indicated that Cr, Ni, Cu, and Zn were mainly from natural contributions, while Pb was influenced by anthropogenic inputs, especially during autumn. The geoaccumulation index of Pb near the mouth of the Yangtze River suggested that the pollution degree in autumn was heavier than that in spring, which might be caused by the greater river discharge in summer and more heavy metal adsorption with finer grain sizes. Copyright © 2017 Elsevier Ltd. All rights reserved.

A photoautotrophic source for lycopane in marine water columns

NASA Technical Reports Server (NTRS)

Wakeham, Stuart G.; Freeman, Katherine H.; Pease, Tamara K.; Hayes, J. M.

1993-01-01

Suspended particulate matter and recent sediments from diverse oceanic sites have been investigated for their contents of lycopane. Lycopane was present in all samples, including both oxic and anoxic water column and sediments. The highest concentrations in the water column were found in surface waters of the central Pacific gyre (1.5 ng/L) and in the anoxic waters of the Cariaco Trench (1.1 ng/L) and the Black Sea (0.3 ng/L). Vertical concentration profiles suggest that lycopane is probably algal in origin. Moreover, biogeochemical conditions in anoxic zones apparently result in a secondary production of lycopane from an as yet unidentified precursor. Compound-specific carbon isotopic analyses have been carried out on lycopane from water column and sediment samples. Isotopic compositions of lycopane range between -23.6 and -32.9 percent and are consistent with a photoautotrophic origin. We postulate that some lycopane is produced in surface waters of the ocean, while additional lycopane is produced in anoxic zones by anaerobic microbial action on an algal precursor.

Including impacts of particulate emissions on marine ecosystems in life cycle assessment: the case of offshore oil and gas production.

PubMed

Veltman, Karin; Huijbregts, Mark A J; Rye, Henrik; Hertwich, Edgar G

2011-10-01

Life cycle assessment is increasingly used to assess the environmental performance of fossil energy systems. Two of the dominant emissions of offshore oil and gas production to the marine environment are the discharge of produced water and drilling waste. Although environmental impacts of produced water are predominantly due to chemical stressors, a major concern regarding drilling waste discharge is the potential physical impact due to particles. At present, impact indicators for particulate emissions are not yet available in life cycle assessment. Here, we develop characterization factors for 2 distinct impacts of particulate emissions: an increased turbidity zone in the water column and physical burial of benthic communities. The characterization factor for turbidity is developed analogous to characterization factors for toxic impacts, and ranges from 1.4 PAF (potentially affected fraction) · m(3) /d/kg(p) (kilogram particulate) to 7.0 x 10³ [corrected] for drilling mud particles discharged from the rig. The characterization factor for burial describes the volume of sediment that is impacted by particle deposition on the seafloor and equals 2.0 × 10(-1) PAF · m(3) /d/kg(p) for cutting particles. This characterization factor is quantified on the basis of initial deposition layer characteristics, such as height and surface area, the initial benthic response, and the recovery rate. We assessed the relevance of including particulate emissions in an impact assessment of offshore oil and gas production. Accordingly, the total impact on the water column and on the sediment was quantified based on emission data of produced water and drilling waste for all oil and gas fields on the Norwegian continental shelf in 2008. Our results show that cutting particles contribute substantially to the total impact of offshore oil and gas production on marine sediments, with a relative contribution of 55% and 31% on the regional and global scale, respectively. In contrast, the contribution of particulate emissions to the total impact on the marine water column is of minor importance. We conclude that particles are an important stressor in marine ecosystems, particularly for marine sediment, and particulate emissions should therefore be included in a (life cycle) impact assessment of offshore oil and gas production. Copyright © 2011 SETAC.

Role of Marine Snows in Microplastic Fate and Bioavailability.

PubMed

Porter, Adam; Lyons, Brett P; Galloway, Tamara S; Lewis, Ceri

2018-06-19

Microplastics contaminate global oceans and are accumulating in sediments at levels thought sufficient to leave a permanent layer in the fossil record. Despite this, the processes that vertically transport buoyant polymers from surface waters to the benthos are poorly understood. Here we demonstrate that laboratory generated marine snows can transport microplastics of different shapes, sizes, and polymers away from the water surface and enhance their bioavailability to benthic organisms. Sinking rates of all tested microplastics increased when incorporated into snows, with large changes observed for the buoyant polymer polyethylene with an increase in sinking rate of 818 m day -1 and for denser polyamide fragments of 916 m day -1 . Incorporation into snows increased microplastic bioavailability for mussels, where uptake increased from zero to 340 microplastics individual -1 for free microplastics to up to 1.6 × 10 5 microplastics individual -1 when incorporated into snows. We therefore propose that marine snow formation and fate has the potential to play a key role in the biogeochemical processing of microplastic pollution.

A mycological baseline study based on a multidisciplinary approach in a coastal area affected by contaminated torrent input.

PubMed

Capello, M; Carbone, C; Cecchi, G; Consani, S; Cutroneo, L; Di Piazza, S; Greco, G; Tolotti, R; Vagge, G; Zotti, M

2017-06-15

Fungi include a vast group of eukaryotic organisms able to colonise different natural, anthropised and extreme environments, including marine areas contaminated by metals. The present study aims to give a first multidisciplinary characterisation of marine bottom sediments contaminated by metals (Cd, Co, Cr, Cu, Ni, and Zn), originating in the water leakage from an abandoned Fe-Cu sulphide mine (Libiola, north-western Italy), and evaluate how the chemical and physical parameters of water and sediments may affect the benthic fungal communities. Our preliminary results showed the high mycodiversity of the marine sediments studied (13 genera and 23 species of marine fungi isolated), and the great physiological adaptability that this mycobiota evolved in reaction to the effects of the ecotoxic bottom sediment contamination, and associated changes in the seawater parameters. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

USGS Publications Warehouse

Rapp, J.B.

1991-01-01

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

Predictive modelling of grain-size distributions from marine electromagnetic profiling data using end-member analysis and a radial basis function network

NASA Astrophysics Data System (ADS)

Baasch, B.; Müller, H.; von Dobeneck, T.

2018-07-01

In this work, we present a new methodology to predict grain-size distributions from geophysical data. Specifically, electric conductivity and magnetic susceptibility of seafloor sediments recovered from electromagnetic profiling data are used to predict grain-size distributions along shelf-wide survey lines. Field data from the NW Iberian shelf are investigated and reveal a strong relation between the electromagnetic properties and grain-size distribution. The here presented workflow combines unsupervised and supervised machine-learning techniques. Non-negative matrix factorization is used to determine grain-size end-members from sediment surface samples. Four end-members were found, which well represent the variety of sediments in the study area. A radial basis function network modified for prediction of compositional data is then used to estimate the abundances of these end-members from the electromagnetic properties. The end-members together with their predicted abundances are finally back transformed to grain-size distributions. A minimum spatial variation constraint is implemented in the training of the network to avoid overfitting and to respect the spatial distribution of sediment patterns. The predicted models are tested via leave-one-out cross-validation revealing high prediction accuracy with coefficients of determination (R2) between 0.76 and 0.89. The predicted grain-size distributions represent the well-known sediment facies and patterns on the NW Iberian shelf and provide new insights into their distribution, transition and dynamics. This study suggests that electromagnetic benthic profiling in combination with machine learning techniques is a powerful tool to estimate grain-size distribution of marine sediments.

Analysis of a PAH-degrading bacterial population in subsurface sediments on the Mid-Atlantic Ridge

NASA Astrophysics Data System (ADS)

Shao, Zongze; Cui, Zhisong; Dong, Chunming; Lai, Qiliang; Chen, Liang

2010-05-01

Little is known about the types and concentrations of polycyclic aromatic hydrocarbons (PAHs) existing in the deep-sea subsurface environment, which is believed to be cold, oligothrophic and of high static pressure. PAHs in the upper layers of the water column are unavoidably subjected to degradation while they are deposited to the sea floor and become embedded in the deep-sea sediment. In this report, a high concentration of PAHs was discovered in the sediment 2.7 m beneath the bottom surface at a water depth of 3962 m on the Mid-Atlantic Ridge (MAR). The total concentration of PAHs was 445 ng (g dry wt sediment) -1. Among the seven detected PAHs, the concentrations of phenanthrene (222 ng g -1) and fluorene (79 ng g -1) were relatively high. In addition, PAH-degrading bacteria were found within the sediments. As in a previously detected site on the MAR, in the PAH-enriched region of this site, a bacterium of the genus Cycloclasticus was found to be the predominant isolate detected by PCR-DGGE analysis. In addition, bacteria of the Halomonas, Marinobacter, Alcanivorax, Thalassospira and Maricaulis genera, were also included in the PAH-degrading community. In summary, a high concentration of PAHs was detected in the subsurface of the deep-sea sediment, and once again, the Cycloclasticus bacterium was confirmed to be a ubiquitous marine PAH degrader even in the subsurface marine environment. Considering the abundance of PAHs therein, biodegradation is thus thought to be inactive, probably because of the low temperature, limited oxygen and/or limited nutrients.

Predictive modelling of grain size distributions from marine electromagnetic profiling data using end-member analysis and a radial basis function network

NASA Astrophysics Data System (ADS)

Baasch, B.; M"uller, H.; von Dobeneck, T.

2018-04-01

In this work we present a new methodology to predict grain-size distributions from geophysical data. Specifically, electric conductivity and magnetic susceptibility of seafloor sediments recovered from electromagnetic profiling data are used to predict grain-size distributions along shelf-wide survey lines. Field data from the NW Iberian shelf are investigated and reveal a strong relation between the electromagnetic properties and grain-size distribution. The here presented workflow combines unsupervised and supervised machine learning techniques. Nonnegative matrix factorisation is used to determine grain-size end-members from sediment surface samples. Four end-members were found which well represent the variety of sediments in the study area. A radial-basis function network modified for prediction of compositional data is then used to estimate the abundances of these end-members from the electromagnetic properties. The end-members together with their predicted abundances are finally back transformed to grain-size distributions. A minimum spatial variation constraint is implemented in the training of the network to avoid overfitting and to respect the spatial distribution of sediment patterns. The predicted models are tested via leave-one-out cross-validation revealing high prediction accuracy with coefficients of determination (R2) between 0.76 and 0.89. The predicted grain-size distributions represent the well-known sediment facies and patterns on the NW Iberian shelf and provide new insights into their distribution, transition and dynamics. This study suggests that electromagnetic benthic profiling in combination with machine learning techniques is a powerful tool to estimate grain-size distribution of marine sediments.

An integrated bioremediation process for petroleum hydrocarbons removal and odor mitigation from contaminated marine sediment.

PubMed

Zhang, Zhen; Lo, Irene M C; Yan, Dickson Y S

2015-10-15

This study developed a novel integrated bioremediation process for the removal of petroleum hydrocarbons and the mitigation of odor induced by reduced sulfur from contaminated marine sediment. The bioremediation process consisted of two phases. In Phase I, acetate was dosed into the sediment as co-substrate to facilitate the sulfate reduction process. Meanwhile, akaganeite (β-FeOOH) was dosed in the surface layer of the sediment to prevent S(2-) release into the overlying seawater. In Phase II, NO3(-) was injected into the sediment as an electron acceptor to facilitate the denitrification process. After 20 weeks of treatment, the sequential integration of the sulfate reduction and denitrification processes led to effective biodegradation of total petroleum hydrocarbons (TPH), in which about 72% of TPH was removed. In Phase I, the release of S(2-) was effectively controlled by the addition of akaganeite. The oxidation of S(2-) by Fe(3+) and the precipitation of S(2-) by Fe(2+) were the main mechanisms for S(2-) removal. In Phase II, the injection of NO3(-) completely inhibited the sulfate reduction process. Most of residual AVS and S(0) were removed within 4 weeks after NO3(-) injection. The 16S rRNA clone library-based analysis revealed a distinct shift of bacterial community structure in the sediment over different treatment phases. The clones affiliated with Desulfobacterales and Desulfuromonadales were the most abundant in Phase I, while the clones related to Thioalkalivibrio sulfidophilus, Thiohalomonas nitratireducens and Sulfurimonas denitrificans predominated in Phase II. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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.

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

NASA Astrophysics Data System (ADS)

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

2013-12-01

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

Secular and environmental constraints on the occurrence of dinosterane in sediments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Summons, R.E.; Boreham, C.J.; Thomas, J.

1992-06-01

The distribution patterns of sedimentary A-ring methylated steranes have changed markedly over geological time. Although dinosterane and its isomer 24-ethyl-4{alpha}-methylcholestane have been tentatively identified in three Proterozoic rock units, they are either not detectable or occur in low abundance relative to 3-methyl steranes throughout most of the Palaeozoic. Between Permian and middle Triassic times (260-220 Ma ago), 4-methyl sterane abundances in marine sediments increased markedly. The presence of dinosterane in some middle Triassic marine sediments is contemporaneous with the appearance of fossil cysts of uncontested dinoflagellate affinity. 4-Methyl steranes, including dinosterane or their precursor sterenes and sterols, then show amore » continuous presence, often in high abundance, in marine sediments from the late Triassic through to the present day. Assemblages of 4-methyl steranes and their precursors, but with dinosterane absent or in low relative abundance, are often the predominant steroids in lacustrine sediments in the Cainozoic. Dinosterane appears to arise predominantly from marine dinoflagellates and, as a consequence, is a useful biological marker for Mesozoic and Cainozoic marine organic matter. The isomer 24-ethyl-4{alpha}-methylcholestane is likely to have multiple origins although its very high abundance in Tertiary lacustrine sediments and oils, compared to older materials, suggests that dinoflagellates could also be the source in these cases.« less

High growth potential and nitrogen removal performance of marine anammox bacteria in shrimp-aquaculture sediment.

PubMed

Van Duc, Luong; Song, Bongkeun; Ito, Hiroaki; Hama, Takehide; Otani, Masashi; Kawagoshi, Yasunori

2018-04-01

Anaerobic ammonium oxidation (anammox) bacteria were enriched in continuous packed-bed columns with marine sediment. One column (SB-C) was packed with only marine sediment collected from a shrimp-aquaculture pond, and another column (SB-AMX) was inoculated with marine anammox bacteria (MAB) as a control. These columns were continuously fed with natural or artificial seawater including ammonium (NH 4 + ) and nitrite (NO 2 - ). The SB-AMX showed anammox activities from the beginning and continued for over 200 days. However, the SB-C had no nitrogen removal performance for over 170 days. After adding a bicarbonate solution (KHCO 3 ) to the sediment-only packed column, anammox activity was observed within 13 days. The column exhibited a nitrogen removal efficiency (NRE) of 88% at a nitrogen loading rate (NLR) of 1.0 kg-N·m -3 ·day -1 , which was comparable to the control one. A next-generation sequencing analysis revealed the predominance of MAB related to "Candidatus Scalindua spp.". In addition, the co-occurrence of sulfur-oxidizing denitrifiers was observed, which suggests their symbiotic relationship. This study suggests the applicability of MAB for in-situ bioremediation of nitrogen-contaminated marine sediments and reveals a potential microbial interaction between anammox and sulfur-oxidizing communities responsible for nitrogen and sulfur cycling in marine aquaculture systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Salmon Aquaculture and Antimicrobial Resistance in the Marine Environment

PubMed Central

Buschmann, Alejandro H.; Tomova, Alexandra; López, Alejandra; Maldonado, Miguel A.; Henríquez, Luis A.; Ivanova, Larisa; Moy, Fred; Godfrey, Henry P.; Cabello, Felipe C.

2012-01-01

Antimicrobials used in salmon aquaculture pass into the marine environment. This could have negative impacts on marine environmental biodiversity, and on terrestrial animal and human health as a result of selection for bacteria containing antimicrobial resistance genes. We therefore measured the numbers of culturable bacteria and antimicrobial-resistant bacteria in marine sediments in the Calbuco Archipelago, Chile, over 12-month period at a salmon aquaculture site approximately 20 m from a salmon farm and at a control site 8 km distant without observable aquaculture activities. Three antimicrobials extensively used in Chilean salmon aquaculture (oxytetracycline, oxolinic acid, and florfenicol) were studied. Although none of these antimicrobials was detected in sediments from either site, traces of flumequine, a fluoroquinolone antimicrobial also widely used in Chile, were present in sediments from both sites during this period. There were significant increases in bacterial numbers and antimicrobial-resistant fractions to oxytetracycline, oxolinic acid, and florfenicol in sediments from the aquaculture site compared to those from the control site. Interestingly, there were similar numbers of presumably plasmid-mediated resistance genes for oxytetracycline, oxolinic acid and florfenicol in unselected marine bacteria isolated from both aquaculture and control sites. These preliminary findings in one location may suggest that the current use of large amounts of antimicrobials in Chilean aquaculture has the potential to select for antimicrobial-resistant bacteria in marine sediments. PMID:22905164

A new look at the multi-G model for organic carbon degradation in surface marine sediments for coupled benthic-pelagic simulations of the global ocean

NASA Astrophysics Data System (ADS)

Stolpovsky, Konstantin; Dale, Andrew W.; Wallmann, Klaus

2018-06-01

The kinetics of particulate organic carbon (POC) mineralization in marine surface sediments is not well constrained. This creates considerable uncertainties when benthic processes are considered in global biogeochemical or Earth system circulation models to simulate climate-ocean interactions and biogeochemical tracer distributions in the ocean. In an attempt to improve our understanding of the rate and depth distribution of organic carbon mineralization in bioturbated (0-20 cm) sediments at the global scale, we parameterized a 1-D diagenetic model that simulates the mineralization of three discrete POC pools (a multi-G model). The rate constants of the three reactive classes (highly reactive, reactive, refractory) are fixed and determined to be 70, 0.5 and ˜ 0.001 yr-1, respectively, based on the Martin curve model for pelagic POC degradation. In contrast to previous approaches, however, the reactivity of the organic material degraded in the seafloor is continuous with, and set by, the apparent reactivity of material sinking through the water column. Despite the simplifications of describing POC remineralization using G-type approaches, the model is able to simulate a global database (185 stations) of benthic oxygen and nitrate fluxes across the sediment-water interface in addition to porewater oxygen and nitrate distributions and organic carbon burial efficiencies. It is further consistent with degradation experiments using fresh phytoplankton reported in a previous study. We propose that an important yet mostly overlooked consideration in upscaling approaches is the proportion of the reactive POC classes reaching the seafloor in addition to their reactivity. The approach presented is applicable to both steady-state and non-steady state scenarios, and links POC degradation kinetics in sedimentary environments to water depth and the POC rain rate to the seafloor.

Present-day palynomorph deposits in an estuarine context: The case of the Loire Estuary

NASA Astrophysics Data System (ADS)

Ganne, A.; Leroyer, C.; Penaud, A.; Mojtahid, M.

2016-12-01

Estuaries are dynamic systems that collect terrestrial, aerial, fluvial, and marine inputs, including organic microfossils, which, when fossilized and observed on palynological slides, are also referred to as palynomorphs (pollen and non-pollen palynomorphs including dinoflagellate cysts or dinocysts). To understand these organic microfossil deposit arrangements across the Loire estuary, palynomorph counts were undertaken in 31 surface sediments collected across longitudinal and perpendicular transects of the Loire active riverbed, from the upper inner estuary to the river mouth. Main results suggest a large homogeneity of the pollen content throughout the entire upstream-downstream transect, with a dominance of arboreal taxa (Pinus, Quercus, Alnus) and Poaceae. Also, perpendicular transects across the channel show a great similarity between the muddy surface layers and the underlying consolidated clay layers. This is probably due to: i) homogeneity of the landscape at a regional scale (large catchment area of the Loire River), and ii) complex hydrodynamic processes involving strong mixing of the palynological signal. Furthermore, despite scarce woodlands in the regional landscape, arboreal pollen (especially Pinus and Quercus) represents > 60% of the total pollen percentages. This could be explained by several factors: i) generally higher arboreal pollen production and dispersion as compared to herbaceous taxa, ii) distant inputs from marine areas downstream and/or forested regions far upstream, and iii) differential selection or inheritance from underlying sediments. Differentiation between the outer and inner estuarine environments was furthermore possible using a ratio of terrestrial versus marine palynological indicators. Among the dinocyst assemblages (marine realm), the euryhaline species Lingulodinium machaerophorum predominates; this taxon being very sensitive to strong water column stratification. Also, total dinocyst concentration increased upstream, which may result from the tidal forcing pushing salinity upriver beneath outflowing river water, and thus signing the estuarine turbidity maximum influence within the Loire River.

Surface sedimentary units of the Gulf of Alaska continental shelf: Montague Island to Yakutat Bay

USGS Publications Warehouse

Molnia, Bruce F.

1977-01-01

Four major sedimentary units occur on the sea floor of the continental shelf in the northern Gulf of Alaska. These units, defined on the basis of seismic and sedimentologic data, are: (1) Holocene sediments, (2) Holocene mind moraines, C3) Quaternary glacial marine sediments, and (4) Tertiary and Pleistocene lithified deposits. A wedge of Holocene fine sand to clayey silt covers most of the inner shelf, reaching maximum thicknesses of about 350 m seaward of the Copper River and about 200 m seaward of Icy Bay. Holocene end moraines are found at the mouth of Icy Bay, south of Bering Glacier, and at the mouth of Yakutat Bay. Quaternary glacial marine sediments are found in a narrow arc that borders, on the north and west side of Tart Bank and in a large arc 20 km or more offshore that parallels the shoreline between Kayak Island and Yakutat Bay. Tertiary or Pleistocene stratified sedimentary rocks, which in profile commonly are folded, faulted, and truncated, crop out on Tarr Bank, offshore of Montague Island, and in several localities southeast and southwest of Cape Yakataga. The lack of Holocene cover on Tarr Bank and Middleton, Kayak and Montague Island platforms may be due to the scouring action of swift bottom currents and large storm waves. West of Kayak Island the Copper River is the primary source of Holocene sediment. East of Kayak Island the major sediment sources are streams draining the larger ice fields, notably, the Malaspina and Bering Glaciers. Transport of bottom and suspended sediment is predominantly to the west. If deglaciation of the shelf was completed by 10,000 years B.P., maximum rates of accumulation of Holocene sediment on the inner shelf may be as high as 10-35 m per 1,000 years.

Shipboard surveys track magnetic sources in marine sediments--geophysical studies of the Stono and North Edisto Inlets near Charleston, South Carolina

USGS Publications Warehouse

Shah, Anjana K.; Harris, M. Scott

2012-01-01

Magnetic field data are traditionally used to analyze igneous and metamorphic rocks, but recent efforts have shown that magnetic sources within sediments may be detectable, suggesting new applications for high-resolution magnetic field surveys. Candidates for sedimentary sources include heavy mineral sand concentrations rich in magnetite or hematite, alteration-induced glauconite, or biogenic magnetite. Magnetic field surveys can be used to map the distributions of such sources with much denser and more widespread coverage than possible by sampling. These data can then provide constraints on the composition history of local sediments. Mapping such sediments requires the sensor to be relatively close to the source, and filtering approaches may be needed to distinguish signals from both system noise and deeper basement features. Marine geophysical surveys conducted in July, 2010, over the Stono and North Edisto River inlets and their riverine inputs south of Charleston, South Carolina, showed 10- to 40-m-wide, 1- to 6-nT magnetic anomalies associated with shallow, sand-covered seabed. These anomalies are distinct from system noise but are too narrow to represent basement features. The anomalies are present mostly in shallow areas where river sediments originating from upland areas enter the inlets. Surface grab samples from the North Edisto River contain trace amounts of heavy mineral sediments including hematite, maghemite, ilmenite, and magnetite, as well as garnet, epidote, zircon, and rutile. Previous stream sediment analyses show enhanced titanium over much of the Atlantic Coastal Plain. The combined data suggest that the anomalies are generated by titanium- and iron-rich heavy mineral sands ultimately originating from the Piedmont and Blue Ridge provinces, which are then reworked and concentrated by tidal currents.

Quantification of Microbial Communities in Subsurface Marine Sediments of the Black Sea and off Namibia.

PubMed

Schippers, Axel; Kock, Dagmar; Höft, Carmen; Köweker, Gerrit; Siegert, Michael

2012-01-01

Organic-rich subsurface marine sediments were taken by gravity coring up to a depth of 10 m below seafloor at six stations from the anoxic Black Sea and the Benguela upwelling system off Namibia during the research cruises Meteor 72-5 and 76-1, respectively. The quantitative microbial community composition at various sediment depths was analyzed using total cell counting, catalyzed reporter deposition - fluorescence in situ hybridization (CARD-FISH) and quantitative real-time PCR (Q-PCR). Total cell counts decreased with depths from 10(9) to 10(10) cells/mL at the sediment surface to 10(7)-10(9) cells/mL below one meter depth. Based on CARD-FISH and Q-PCR analyses overall similar proportions of Bacteria and Archaea were found. The down-core distribution of prokaryotic and eukaryotic small subunit ribosomal RNA genes (16S and 18S rRNA) as well as functional genes involved in different biogeochemical processes was quantified using Q-PCR. Crenarchaeota and the bacterial candidate division JS-1 as well as the classes Anaerolineae and Caldilineae of the phylum Chloroflexi were highly abundant. Less abundant but detectable in most of the samples were Eukarya as well as the metal and sulfate-reducing Geobacteraceae (only in the Benguela upwelling influenced sediments). The functional genes cbbL, encoding for the large subunit of RuBisCO, the genes dsrA and aprA, indicative of sulfate-reducers as well as the mcrA gene of methanogens were detected in the Benguela upwelling and Black Sea sediments. 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.

Oceanographic gradients and seabird prey community dynamics in glacial fjords

USGS Publications Warehouse

Arimitsu, Mayumi L.; Piatt, John F.; Madison, Erica N.; Conaway, Jeffrey S.; Hillgruber, N.

2012-01-01

Glacial fjord habitats are undergoing rapid change as a result of contemporary global warming, yet little is known about how glaciers influence marine ecosystems. These ecosystems provide important feeding, breeding and rearing grounds for a wide variety of marine organisms, including seabirds of management concern. To characterize ocean conditions and marine food webs near tidewater glaciers, we conducted monthly surveys of oceanographic variables, plankton, fish and seabirds in Kenai Fjords, Alaska, from June to August of 2007 and 2008. We also measured tidal current velocities near glacial features. We found high sediment load from glacial river runoff played a major role in structuring the fjord marine ecosystem. Submerged moraines (sills) isolated cool, fresh, stratified and silt-laden inner fjord habitats from oceanic influence. Near tidewater glaciers, surface layers of turbid glacial runoff limited availability of light to phytoplankton, but macrozooplankton were abundant in surface waters, perhaps due to the absence of a photic cue for diel migration. Fish and zooplankton community structure varied along an increasing temperature gradient throughout the summer. Acoustic measurements indicated that low density patches of fish and zooplankton were available in the surface waters near glacial river outflows. This is the foraging habitat occupied most by Kittlitz's murrelet (Brachyramphus brevirostris), a rare seabird that appears to be specialized for life in glacially influenced environments. Kittlitz's murrelets were associated with floating glacial ice, and they were more likely to occur near glaciers, in deeper water, and in areas with high acoustic backscatter. Kittlitz's murrelet at-sea distribution was limited to areas influenced by turbid glacial outflows, and where prey was concentrated near the surface in waters with low light penetration. Tidewater glaciers impart unique hydrographic characteristics that influence marine plankton and fish communities, and this has cascading effects on marine food webs in these ecosystems.

Clostridium perfringens in Long Island Sound sediments: An urban sedimentary record

USGS Publications Warehouse

Buchholtz ten Brink, Marilyn R.; Mecray, E.L.; Galvin, E.L.

2000-01-01

Clostridium perfringens is a conservative tracer and an indicator of sewage-derived pollution in the marine environment. The distribution of Clostridium perfringens spores was measured in sediments from Long Island Sound, USA, as part of a regional study designed to: (1) map the distribution of contaminated sediments; (2) determine transport and dispersal paths; (3) identify the locations of sediment and contaminant focusing; and (4) constrain predictive models. In 1996, sediment cores were collected at 58 stations, and surface sediments were collected at 219 locations throughout the Sound. Elevated concentrations of Clostridium perfringens in the sediments indicate that sewage pollution is present throughout Long Island Sound and has persisted for more than a century. Concentrations range from undetectable amounts to 15,000 spores/g dry sediment and are above background levels in the upper 30 cm at nearly all core locations. Sediment focusing strongly impacts the accumulation of Clostridium perfringens spores. Inventories in the cores range from 28 to 70,000 spores/cm2, and elevated concentrations can extend to depths of 50 cm. The steep gradients in Clostridium perfringens profiles in muddier cores contrast with concentrations that are generally constant with depth in sandier cores. Clostridium perfringens concentrations rarely decrease in the uppermost sediment, unlike those reported for metal contaminants. Concentrations in surface sediments are highest in the western end of the Sound, very low in the eastern region, and intermediate in the central part. This pattern reflects winnowing and focusing of Clostridium perfringens spores and fine-grained sediment by the hydrodynamic regime; however, the proximity of sewage sources to the westernmost Sound locally enhances the Clostridium perfringens signals.

Contribution of wave-induced liquefaction in triggering hyperpycnal flows in Yellow River Estuary

NASA Astrophysics Data System (ADS)

Liu, X.; Jia, Y.

2017-12-01

Hyperpycnal flows, driven mainly by the gravity of near-bed negatively buoyant layers, are one of the most important processes for moving marine sediment across the earth. The issue of hyperpycnal flows existing in marine environment has drawn increasing scholars' attention since that was observed in situ off the Yellow River estuary in the 1980s. Most researches maintain that hyperpycnal flows in the Yellow River estuary are caused by the high-concentration sediments discharged from the Yellow River into sea, however, other mechanisms have been discounted since the sediment input from the river has been significantly changed due to climate and anthropogenic change. Here we demonstrate that wave-seabed interactions can generate hyperpycnal flows, without river input, by sediment flux convergence above an originally consolidated seabed. Using physical model experiments and multi-sensor field measurements, we characterize the composition-dependent liquefaction properties of the sediment due to wave-induced pore water pressure accumulation. This allows quantification of attenuation of sediment threshold velocity and critical shear stress (predominant variables in transport mechanics) during the liquefaction under waves. Parameterising the wave-seabed interactions in a new concept model shows that high waves propagating over the seabed sediment can act as a scarifier plough remoulding the seabed sediment. This contributes to marine hyperpycnal flows as the sediment is quickly resuspended under accumulating attenuation in strength. Therefore, the development of more integrative numerical models could supply realistic predictions of marine record in response to rising magnitude and frequency of storms.

Microbenthic community structure and trophic status of sediments in the Mar Piccolo of Taranto (Mediterranean, Ionian Sea).

PubMed

Rubino, F; Cibic, T; Belmonte, M; Rogelja, M

2016-07-01

This study aimed to assess the benthic ecosystem trophic status in a heavily polluted marine area and the response of the microbenthic community to multiple and diffuse anthropogenic impacts, integrating information coming from the active and resting (plankton's cysts) components of microbenthos. Two sampling campaigns were carried out in the period 2013-2014 and four sampling sites at different levels of industrial contamination were chosen within the first and second inlet of the Mar Piccolo of Taranto. The chemical contamination affected to a higher extent the active microbenthos than the resting one. In the central part of the first inlet, characterised by more marine features, thrives a very rich and biodiverse microbenthic community. In contrast, at the polluted site near the military navy arsenal, extremely low densities (9576 ± 1732 cells cm(-3)) were observed for active microbenthos, but not for the resting community. Here, the high level of contamination selected for tychopelagic diatom species, i.e., thriving just above the surface sediments, while the other life forms died or moved away. Following the adoption of a 10 μm mesh, for the first time, resting spores produced by small diatoms of the genus Chaetoceros were found. Our results further indicate that although the Mar Piccolo is very shallow, the benthic system is scarcely productive, likely as a consequence of the accumulated contaminants in the surface sediments that probably interfere with the proper functioning of the benthic ecosystem.

Chemical speciation and ecological risk assessment of arsenic in marine sediments from Izmir Bay (Eastern Aegean Sea).

PubMed

Gonul, L T

2015-12-01

Total arsenic, arsenic(III) and (V), Fe, and Mn were measured in 17 surface sediment samples from Izmir Bay. The concentrations and ecological risk of As were characterized in the sediment affected by urban and agricultural activities. Total As ranged from 8.87 to 28.3 μg g(-1) dry weight (96.5-99.9 % as inorganic As). Distribution of total As and total As/Fe followed a different trend in sediments at all sampling sites. Arsenite (As(III)) was the most dominant form followed by As(V), while organic arsenic represented a minor constituent (0.03 to 3.49 %). The highest concentration of total As was observed at Gediz River estuary and exceeded lower threshold value (threshold effects level (TEL)). Due to the biological reduction of As(V) and abundance of Fe (oxyhydr)oxides in the sediments, most inorganic As in the Izmir Bay was present as As(III). Besides, the levels of As were >TEL and

The deep sea is a major sink for microplastic debris

PubMed Central

Woodall, Lucy C.; Sanchez-Vidal, Anna; Canals, Miquel; Paterson, Gordon L.J.; Coppock, Rachel; Sleight, Victoria; Calafat, Antonio; Rogers, Alex D.; Narayanaswamy, Bhavani E.; Thompson, Richard C.

2014-01-01

Marine debris, mostly consisting of plastic, is a global problem, negatively impacting wildlife, tourism and shipping. However, despite the durability of plastic, and the exponential increase in its production, monitoring data show limited evidence of concomitant increasing concentrations in marine habitats. There appears to be a considerable proportion of the manufactured plastic that is unaccounted for in surveys tracking the fate of environmental plastics. Even the discovery of widespread accumulation of microscopic fragments (microplastics) in oceanic gyres and shallow water sediments is unable to explain the missing fraction. Here, we show that deep-sea sediments are a likely sink for microplastics. Microplastic, in the form of fibres, was up to four orders of magnitude more abundant (per unit volume) in deep-sea sediments from the Atlantic Ocean, Mediterranean Sea and Indian Ocean than in contaminated sea-surface waters. Our results show evidence for a large and hitherto unknown repository of microplastics. The dominance of microfibres points to a previously underreported and unsampled plastic fraction. Given the vastness of the deep sea and the prevalence of microplastics at all sites we investigated, the deep-sea floor appears to provide an answer to the question—where is all the plastic? PMID:26064573

The deep sea is a major sink for microplastic debris.

PubMed

Woodall, Lucy C; Sanchez-Vidal, Anna; Canals, Miquel; Paterson, Gordon L J; Coppock, Rachel; Sleight, Victoria; Calafat, Antonio; Rogers, Alex D; Narayanaswamy, Bhavani E; Thompson, Richard C

2014-12-01

Marine debris, mostly consisting of plastic, is a global problem, negatively impacting wildlife, tourism and shipping. However, despite the durability of plastic, and the exponential increase in its production, monitoring data show limited evidence of concomitant increasing concentrations in marine habitats. There appears to be a considerable proportion of the manufactured plastic that is unaccounted for in surveys tracking the fate of environmental plastics. Even the discovery of widespread accumulation of microscopic fragments (microplastics) in oceanic gyres and shallow water sediments is unable to explain the missing fraction. Here, we show that deep-sea sediments are a likely sink for microplastics. Microplastic, in the form of fibres, was up to four orders of magnitude more abundant (per unit volume) in deep-sea sediments from the Atlantic Ocean, Mediterranean Sea and Indian Ocean than in contaminated sea-surface waters. Our results show evidence for a large and hitherto unknown repository of microplastics. The dominance of microfibres points to a previously underreported and unsampled plastic fraction. Given the vastness of the deep sea and the prevalence of microplastics at all sites we investigated, the deep-sea floor appears to provide an answer to the question-where is all the plastic?

Diversity and Distribution Characteristics of Viruses in Soils of a Marine-Terrestrial Ecotone in East China.

PubMed

Yu, Dan-Ting; Han, Li-Li; Zhang, Li-Mei; He, Ji-Zheng

2018-02-01

A substantial gap remains in our understanding of the abundance, diversity, and ecology of viruses in soil although some advances have been achieved in recent years. In this study, four soil samples according to the salinity gradient from shore to inland in East China have been characterized. Results showed that spherical virus particles represented the largest viral component in all of the four samples. The viromes had remarkably different taxonomic compositions, and most of the sequences were derived from single-stranded DNA viruses, especially from families Microviridae and Circoviridae. Compared with viromes from other aquatic and sediment samples, the community compositions of our four soil viromes resembled each other, meanwhile coastal sample virome closely congregated with sediment and hypersaline viromes, and high salinity paddy soil sample virome was similar with surface sediment virome. Phylogenetic analysis of functional genes showed that four viromes have high diversity of the subfamily Gokushovirinae in family Microviridae and most of Circoviridae replicase protein sequences grouped within the CRESS-DNA viruses. This work provided an initial outline of the viral communities in marine-terrestrial ecotone and will improve our understanding of the ecological functions of soil viruses.

Mineral ecophysiological evidence for microbial activity in banded iron formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Dr. Yi-Liang; Konhauser, Dr, Kurt; Cole, David R

2011-01-01

The phosphorus composition of banded-iron formations (BIFs) has been used as a proxy for Precambrian seawater composition and the paleoeredox state of Earth's surface environment. However, it is unclear whether the phosphorus in BIFs originally entered the sediment as a sorbed component of the iron oxyhydroxide particles, or whether it was incorporated into the biomass of marine phytoplankton. We conducted high-resolution mineral analyses and report here the first detection of an Fe(III) acetate salt, as well as nanocrystals of apatite in association with magnetite, in the 2.48 Ga Dales Gorge Member of the Brockman Iron Formation (a BIF), Hamersley, Westernmore » Australia. The clusters of apatite are similar in size and morphology to biogenic apatite crystals resulting from biomass decay in Phanerozoic marine sediments, while the formation of an Fe(III) acetate salt and magnetite not only implies the original presence of biomass in the BIF sediments, but also that organic carbon likely served as an electron donor during bacterial Fe(III) reduction. This study is important because it suggests that phytoplankton may have played a key role in the transfer of phosphorus (and other trace elements) from the photic zone to the seafloor.« less

Release of Black Carbon From Thawing Permafrost Estimated by Sequestration Fluxes in the East Siberian Arctic Shelf Recipient

NASA Astrophysics Data System (ADS)

Salvadó, Joan A.; Bröder, Lisa; Andersson, August; Semiletov, Igor P.; Gustafsson, Örjan

2017-10-01

Black carbon (BC) plays an important role in carbon burial in marine sediments globally. Yet the sequestration of BC in the Arctic Ocean is poorly understood. Here we assess the concentrations, fluxes, and sources of soot BC (SBC)—the most refractory component of BC—in sediments from the East Siberian Arctic Shelf (ESAS), the World's largest shelf sea system. SBC concentrations in the contemporary shelf sediments range from 0.1 to 2.1 mg g-1 dw, corresponding to 2-12% of total organic carbon. The 210Pb-derived fluxes of SBC (0.42-11 g m-2 yr-1) are higher or in the same range as fluxes reported for marine surface sediments closer to anthropogenic emissions. The total burial flux of SBC in the ESAS ( 4,000 Gg yr-1) illustrates the great importance of this Arctic shelf in marine sequestration of SBC. The radiocarbon signal of the SBC shows more depleted yet also more uniform signatures (-721 to -896‰; average of -774 ± 62‰) than of the non-SBC pool (-304 to -728‰; average of -491 ± 163‰), suggesting that SBC is coming from an, on average, 5,900 ± 300 years older and more specific source than the non-SBC pool. We estimate that the atmospheric BC input to the ESAS is negligible ( 0.6% of the SBC burial flux). Statistical source apportionment modeling suggests that the ESAS sedimentary SBC is remobilized by thawing of two permafrost carbon (PF/C) systems: surface soil permafrost (topsoil/PF; 25 ± 8%) and Pleistocene ice complex deposits (ICD/PF; 75 ± 8%). The SBC contribution to the total mobilized permafrost carbon (PF/C) increases with increasing distance from the coast (from 5 to 14%), indicating that the SBC is more recalcitrant than other forms of translocated PF/C. These results elucidate for the first time the key role of permafrost thaw in the transport of SBC to the Arctic Ocean. With ongoing global warming, these findings have implications for the biogeochemical carbon cycle, increasing the size of this refractory carbon pool in the Arctic Ocean.

The causes of covariation between C and O isotopes in the inorganic carbonate record

NASA Astrophysics Data System (ADS)

Swart, Peter; Oehlert, Amanda

2017-04-01

The δ13C values of carbonate rocks are widely used as proxies for understanding the global carbon cycle. While most workers would prefer to use δ13C values measured in oceanic sediments, during older times the only records that exist are those found in sediments deposited in epeiric seas or on continental margins and carbonate platforms. However, such records are often compromised by near surface diagenesis and therefore care must be taken to exclude altered records. One approach, which has been widely applied, has been to examine the covariation between δ13C and δ18O values, where a positive covariation has been suggested to indicate alteration. In order to test this assumption we present data from a core taken in the Bahamas that has been unequivocally subjected to both freshwater and marine diagenetic processes. Our data suggest that the majority of the zone which has been altered by freshwater shows no correlation between δ13C and δ18O values, with small intervals associated with sub-aerial exposure exhibiting inverse correlations, and only the upper partially altered portion of the core exhibiting positive relationships. The zone below the region of freshwater alteration, previously interpreted as being the mixing-zone, is characterized by a strong covariation between δ13C and δ18O values as a result of the upper portion of this zone having been affected by fresh water diagenesis compared to the lower portion. Within the marine influenced realm a variety of relationships are produced as a result of differences in sediment origin and diagenesis. For example, non-depositional surfaces, where marine diagenetic processes are maximized, are typically expressed by sharp positive correlations between δ13C and δ18O values, while changes related to different sediment sources are expressed as weak positive covariations. While the data set presented here may not be applicable in every situation, the study certainly emphasizes that care must be taken when rules of thumb such as covariation of δ13C and δ18O values suggest diagenesis.

Multitaxon activity profiling reveals differential microbial response to reduced seawater pH and oil pollution.

PubMed

Coelho, Francisco J R C; Cleary, Daniel F R; Costa, Rodrigo; Ferreira, Marina; Polónia, Ana R M; Silva, Artur M S; Simões, Mário M Q; Oliveira, Vanessa; Gomes, Newton C M

2016-09-01

There is growing concern that predicted changes to global ocean chemistry will interact with anthropogenic pollution to significantly alter marine microbial composition and function. However, knowledge of the compounding effects of climate change stressors and anthropogenic pollution is limited. Here, we used 16S and 18S rRNA (cDNA)-based activity profiling to investigate the differential responses of selected microbial taxa to ocean acidification and oil hydrocarbon contamination under controlled laboratory conditions. Our results revealed that a lower relative abundance of sulphate-reducing bacteria (Desulfosarcina/Desulfococcus clade) due to an adverse effect of seawater acidification and oil hydrocarbon contamination (reduced pH-oil treatment) may be coupled to changes in sediment archaeal communities. In particular, we observed a pronounced compositional shift and marked reduction in the prevalence of otherwise abundant operational taxonomic units (OTUs) belonging to the archaeal Marine Benthic Group B and Marine Hydrothermal Vent Group (MHVG) in the reduced pH-oil treatment. Conversely, the abundance of several putative hydrocarbonoclastic fungal OTUs was higher in the reduced pH-oil treatment. Sediment hydrocarbon profiling, furthermore, revealed higher concentrations of several alkanes in the reduced pH-oil treatment, corroborating the functional implications of the structural changes to microbial community composition. Collectively, our results advance the understanding of the response of a complex microbial community to the interaction between reduced pH and anthropogenic pollution. In future acidified marine environments, oil hydrocarbon contamination may alter the typical mixotrophic and k-/r-strategist composition of surface sediment microbiomes towards a more heterotrophic state with lower doubling rates, thereby impairing the ability of the ecosystem to recover from acute oil contamination events. © 2016 John Wiley & Sons Ltd.

Global pulses of organic carbon burial in deep-sea sediments during glacial maxima

PubMed Central

Cartapanis, Olivier; Bianchi, Daniele; Jaccard, Samuel L.; Galbraith, Eric D.

2016-01-01

The burial of organic carbon in marine sediments removes carbon dioxide from the ocean–atmosphere pool, provides energy to the deep biosphere, and on geological timescales drives the oxygenation of the atmosphere. Here we quantify natural variations in the burial of organic carbon in deep-sea sediments over the last glacial cycle. Using a new data compilation of hundreds of sediment cores, we show that the accumulation rate of organic carbon in the deep sea was consistently higher (50%) during glacial maxima than during interglacials. The spatial pattern and temporal progression of the changes suggest that enhanced nutrient supply to parts of the surface ocean contributed to the glacial burial pulses, with likely additional contributions from more efficient transfer of organic matter to the deep sea and better preservation of organic matter due to reduced oxygen exposure. These results demonstrate a pronounced climate sensitivity for this global carbon cycle sink. PMID:26923945

Increased sediment loads cause non-linear decreases in seagrass suitable habitat extent

PubMed Central

Atkinson, Scott; Klein, Carissa Joy; Weber, Tony; Possingham, Hugh P.

2017-01-01

Land-based activities, including deforestation, agriculture, and urbanisation, cause increased erosion, reduced inland and coastal water quality, and subsequent loss or degradation of downstream coastal marine ecosystems. Quantitative approaches to link sediment loads from catchments to metrics of downstream marine ecosystem state are required to calculate the cost effectiveness of taking conservation actions on land to benefits accrued in the ocean. Here we quantify the relationship between sediment loads derived from landscapes to habitat suitability of seagrass meadows in Moreton Bay, Queensland, Australia. We use the following approach: (1) a catchment hydrological model generates sediment loads; (2) a statistical model links sediment loads to water clarity at monthly time-steps; (3) a species distribution model (SDM) factors in water clarity, bathymetry, wave height, and substrate suitability to predict seagrass habitat suitability at monthly time-steps; and (4) a statistical model quantifies the effect of sediment loads on area of seagrass suitable habitat in a given year. The relationship between sediment loads and seagrass suitable habitat is non-linear: large increases in sediment have a disproportionately large negative impact on availability of seagrass suitable habitat. Varying the temporal scale of analysis (monthly vs. yearly), or varying the threshold value used to delineate predicted seagrass presence vs. absence, both affect the magnitude, but not the overall shape, of the relationship between sediment loads and seagrass suitable habitat area. Quantifying the link between sediment produced from catchments and extent of downstream marine ecosystems allows assessment of the relative costs and benefits of taking conservation actions on land or in the ocean, respectively, to marine ecosystems. PMID:29125843

Chemical composition of sediments from White Sea, Russian Arctic

NASA Astrophysics Data System (ADS)

Gamza, Olga; Shevchenko, Vladimir; Novigatsky, Aleksandr

2010-05-01

The White Sea, the only Russian inland sea, is located on the north of outlying districts of the European part of Russia, belongs to Arctic Ocean. Area of water of sea occupies about 90 tousend square kilometers. The sea can be divided into some general parts: neck, funnel, basin and 4 Bays: Dvina Bay, Kandalaksha Bay, Mezen Bay and Onega Bay. The purpose of this work was geochemical mapping of the surface sediments of this area. The main tasks were: compilation data base of element composition of the surface sediments, geochemical mapping of each element, research of the anormal concentration of elements on the surface. To detect the content of chemical elements several methods were used: atomic absorption spectrometry (P.P. Shirshov Institute of Oceanology); neutron activation analysis (Vernadsky Institute of Geochemistry and Analytical Chemistry), total and organic carbon analysis, photometric method to detection Si, Al, P (P.P. Shirshov Institute of Oceanology). Bulk composition is one of the fundamental characteristics of sediments and bottom deposites of modern basins. Coarse-grained sediments with portion of pelitic component <50% is spread on the shallow area (Kandalaksha Bay), in areas with high hydrodynamic activity of near-bottom water. Under the conditions of their low activity, fine-grained facies are common(>80%). Character of elements distribution correlates with facial distribution of sediments from White Sea. According to litologic description, bottom surface of Dvina Bay is practically everywhere covered by layer of fine-grained sand. In the border area between Dvina Bay and White Sea basin on terraced subwater slope aleurite politic silts are abundant. They tend to exhange down the slope to clay silts. In Onega Bay fractions of non-deposition are observed. They are characterized by wide spread of thin blanket poorgraded sediments, which are likely to be relic. Relief of Kandalakscha Bay bottom is presented as alternation of abyssal fosses (near 300 m) with silles and elevations (<20 m), and also numerous islands. Thus variety of sediment composition is observed here - from rules and gravels to fine-grained clay silts [1]. The map of distribution of chemical elements was created by using bulk composition data with the help of program ArcView. Mn distribution in sedimentation mass is largely determed by influence of redox diagenesis. Reactive form of Mn dominates over less moving, litogenic form in sedimation mass of White Sea. Litogenic form remains in sediment, reactive form moves into silt near-bottom water, resulting Mn migration both in sediment and near-bottom layer of marine water. Mn oxidizes on the contact with oxygen of marine water and alters into insoluble form MnO2, causing Mn enrichment of surface layer of sediments. Highly movable silt deposit MnO2 and enriched by Mn suspension are moved by underflow and accumulate in bottom depressions and in central part of the sea, which is quite wide from both places of original sedimentation and run off sources [2]. Thus, the interrelation between granulometric composition of sediment and materials concentration can be shown by the example of Mn. Local conditions, leading to accumulation of clastic components, are: 1. Rise of content in sand owning to separation of heavy minerals 2. Rise of content in surface, mainly sandy clay sediments owning to presence of concretions 3. Rise of content in lower bunches roof owning to diagenetic contraction. Authors thank academic Lisitsyn for encourage, Andrey Apletalin for valuable help, and everybody, who helped in field and laboratory research of the White sea sediments. Work was being done under the auspices of Russian foundation of basic research (grants 09-05-10081, 09-05-00658 and 08-05-00860), RSA presidiums program of 17 fundamental researches (project 17.1). References: 1.Kuzmina T., Lein A., Lutchsheva L., Murdmaa I., Novigatsky A., Shevchenko V. Chemical composition of White Sea's sediments // Litology and mineral deposits . 2009. - № 2. - P 115-132. 2.Nevessky E., Medvedev V. , Kalinenko V. White sea, sedimentation and holocoen developmental history. - Moscow.: Nauka, 1977. - 236 p. 3.White Sea and it water collection affected by climatic and antropogenic factors. / under the editorship of Terzhevik A., Filatov N. - Petrozavodsk.: Karelsky nauchny centr RAN, 2007. - 335p

ACEX: A First Look at Arctic Ocean Cenozoic History

NASA Astrophysics Data System (ADS)

Moran, K.; Backman, J.

2004-12-01

The first Integrated Ocean Drilling Program mission specificplatform expedition (ACEX - Arctic Coring Expedition) drilled and recovered core from five holes at four sites through Cenozoic sediments draping the crest of the Lomonosov Ridge in the central Arctic Ocean. Coring continued into the underlying Cretaceous sedimentary bedrock. Sites are located only a few nautical miles apart along a single seismic line (AWI-91090), showing an identical and coherent Cenozoic seismostratigraphy. Preliminary results from shipboard investigations of core-catcher-based bio- and lithostratigraphy, pore water analyses and core logger data describe a thick (~160 m) middle Miocene through Pleistocene sequence that shows large amplitude, cyclic variability in the density, magnetic susceptibility and acoustic velocity of the sediments. Sediments are largely carbonate free. Pleistocene sedimentation rates are close to 3 cm/ka, whereas Pliocene sediments are by-and-large missing. A sharp change in physical properties at ~200 m defines the transition into a 200+ m thick Paleogene sequence that is initially dominated by large numbers of dinoflagellate cysts. The early Miocene, Oligocene and late Eocene appear to be largely missing in a hiatus. However, a 32 m thick interval separates the overlying middle Miocene from the underlying middle Eocene and presumably preserves some of the early Neogene and late Paleogene sections. Dinoflagellate cysts, diatoms, ebridians and silicoflagellates are common to abundant in the middle Eocene section, which bottoms in a spectacular layer showing massive occurrences of glochidia and massulae (megaspores) of the freshwater hydropterid fern Azolla (duckweed) at the early/middle Eocene boundary (~306 m), suggesting strongly reduced surface water salinity or perhaps even a brief episode of fresh water conditions at the surface. Biosilica is not present prior to the late early Eocene (~320 m). The (sub-) tropical dinoflagellate species Apectodinium augustum occurs abundantly at around 380m in pyrite-rich mudstones, indicating that the Paleocene/Eocene boundary and the associated Carbon Isotope Excursion (CIE) interval were recovered, and that the Arctic Ocean experienced surface temperatures on the order of 20°C during the Paleocene Eocene Thermal Maximum (PETM). Benthic foraminifers indicate that the early Eocene through latest Paleocene sediments were deposited in shallow-marine, neritic to inner neritic, environments. The mudstone of late Paleocene age rests unconformably on Campanian marine sands, sandstone and mudstone.

Seawater as the source of minor elements in black shales, phosphorites and other sedimentary rocks

USGS Publications Warehouse

Piper, D.Z.

1994-01-01

Many of the minor elements in seawater today have a concentration-depth profile similar to that of the biologically essential nutrients, NO-3 and PO3-4. They show a relative depletion in the photic zone and enrichment in the deep ocean. The difference between their surface- and deep-ocean values, normalized to the change in PO3-4, approaches the average of measured minor-element: P ratios in marine plankton, although individual analyses of the latter show extreme scatter for a variety of reasons. Despite this scatter in the minor-element analyses of plankton, agreement between the two sets of data shows unequivocally that an important marine flux of many minor elements through the ocean is in the form of biogenic matter, with a composition approaching that of plankton. This interpretation is further supported by sediment studies, particularly of sediments which accumulate in shelf-slope environments where biological productivity in the photic zone is exceptionally high and organic carbon contents of the underlying sediment elevated. The interelement relations observed for some of these sediments approach the average values of plankton. These same interelement relations are observed in many marine sedimentary rocks such as metalliferous black shales and phosphorites, rocks which have a high content of marine fractions (e.g., organic matter, apatite, biogenic silica and carbonates). Many previous studies of the geochemistry of these rocks have concluded that local hydrothermal activity, and/or seawater with an elemental content different from that of the modern ocean, was required to account for their minor-element contents. However, the similarity in several of the minor-element ratios in many of these formations to minor-element ratios in modern plankton demonstrates that these sedimentary rocks accumulated in environments whose marine chemistry was virtually identical to that seen on continental shelf-slopes, or in marginal seas, of the ocean today. The accumulation of the marine fraction of minor elements on these ancient sea floors was determined largely by the accumulation of organic matter, settling from the photic zone and with a composition of average plankton. A second marine fraction of minor elements in these rocks accumulated through precipitation and adsorption from seawater. The suite of elements in this fraction reflects redox conditions in the bottom water, as determined by bacterial respiration. For example, high Mn, high Cr+V and high Mo concentrations, above those which can be attributed to the accumulation of planktonic matter, characterize accumulation under bottom-water oxidizing, denitrifying and sulfate-reducing conditions, respectively. ?? 1994.

Textural characteristics and sedimentary environment of sediment at eroded and deposited regions in the severely eroded coastline of Batu Pahat, Malaysia.

PubMed

Wan Mohtar, Wan Hanna Melini; Nawang, Siti Aminah Bassa; Abdul Maulud, Khairul Nizam; Benson, Yannie Anak; Azhary, Wan Ahmad Hafiz Wan Mohamed

2017-11-15

This study investigates the textural characteristics of sediments collected at eroded and deposited areas of highly severed eroded coastline of Batu Pahat, Malaysia. Samples were taken from systematically selected 23 locations along the 67km stretch of coastline and are extended to the fluvial sediments of the main river of Batu Pahat. Grain size distribution analysis was conducted to identify its textural characteristics and associated sedimentary transport behaviours. Sediments obtained along the coastline were fine-grained material with averaged mean size of 7.25 ϕ, poorly sorted, positively skewed and has wide distributions. Samples from eroded and deposition regions displayed no distinctive characteristics and exhibited similar profiles. The high energy condition transported the sediments as suspension, mostly as pelagic and the sediments were deposited as shallow marine and agitated deposits. The fluvial sediments of up to 3km into the river have particularly similar profile of textural characteristics with the neighbouring marine sediments from the river mouth. Profiles were similar with marine sediments about 3km opposite the main current and can go up to 10km along the current of Malacca Straits. Copyright © 2017 Elsevier B.V. All rights reserved.

Heavy metals in marine coastal sediments: assessing sources, fluxes, history and trends.

PubMed

Frignani, Mauro; Bellucci, Luca Giorgio

2004-01-01

Examples are presented from the Adriatic Sea, the Ligurian Sea and the Venice Lagoon to illustrate different approaches to the study of anthropogenic metals in marine coastal sediments. These examples refer to studies of areal distribution and transport mechanisms, individuation of the sources, sediment dating, chronology of the fluxes, present and past trends. In particular, some of the findings achieved in studying the Venice Lagoon are discussed from the point of view of anthropogenic changes both in sediment composition and contaminant fluxes.

Microplastics in the Antarctic marine system: An emerging area of research.

PubMed

Waller, Catherine L; Griffiths, Huw J; Waluda, Claire M; Thorpe, Sally E; Loaiza, Iván; Moreno, Bernabé; Pacherres, Cesar O; Hughes, Kevin A

2017-11-15

It was thought that the Southern Ocean was relatively free of microplastic contamination; however, recent studies and citizen science projects in the Southern Ocean have reported microplastics in deep-sea sediments and surface waters. Here we reviewed available information on microplastics (including macroplastics as a source of microplastics) in the Southern Ocean. We estimated primary microplastic concentrations from personal care products and laundry, and identified potential sources and routes of transmission into the region. Estimates showed the levels of microplastic pollution released into the region from ships and scientific research stations were likely to be negligible at the scale of the Southern Ocean, but may be significant on a local scale. This was demonstrated by the detection of the first microplastics in shallow benthic sediments close to a number of research stations on King George Island. Furthermore, our predictions of primary microplastic concentrations from local sources were five orders of magnitude lower than levels reported in published sampling surveys (assuming an even dispersal at the ocean surface). Sea surface transfer from lower latitudes may contribute, at an as yet unknown level, to Southern Ocean plastic concentrations. Acknowledging the lack of data describing microplastic origins, concentrations, distribution and impacts in the Southern Ocean, we highlight the urgent need for research, and call for routine, standardised monitoring in the Antarctic marine system. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Shoreface to estuarine sedimentation in the late Paleocene Matanomadh Formation, Kachchh, western India

NASA Astrophysics Data System (ADS)

Srivastava, V. K.; Singh, B. P.

2017-04-01

Late Paleocene sedimentation in the pericratonic Kachchh Basin marks the initial marine transgression during the Cenozoic era. A 17 m thick sandstone-dominated succession, known as the clastic member (CM) of the Matanomadh Formation (MF), is exposed sporadically in the basin. Three facies associations are reconstructed in the succession in three different sections. Facies association-1 contains matrix-supported pebbly conglomerate facies, horizontally-laminated sandstone-mudstone alternation facies, hummocky- and swaley cross-bedded sandstone facies, wave-rippled sandstone facies and climbing ripple cross-laminated sandstone facies. This facies association developed between shoreface and foreshore zone under the influence of storms on a barrier ridge. Facies association-2 contains sigmoidal cross-bedded sandstone facies, sandstone-mudstone alternation facies, flaser-bedded sandstone facies, herringbone cross-bedded sandstone facies and tangential cross-bedded sandstone facies. This facies association possessing tidal bundles and herringbone cross-beds developed on a tidal flat with strong tidal influence. Facies association-3 comprises pebbly sandstone facies, horizontally-bedded sandstone facies, tangential cross-bedded sandstone facies exhibiting reactivation surfaces and tabular cross-bedded sandstone facies. This facies association represents sedimentation in a river-dominated estuary and reactivation surfaces and herringbone cross-beds indicating tidal influence. The bipolar paleocurrent pattern changes to unipolar up-section because of the change in the depositional currents from tidal to fluvial. The sedimentation took place in an open coast similar to the Korean coast. The presence of neap-spring tidal rhythmites further suggests that a semidiurnal system similar to the modern day Indian Ocean was responsible for the sedimentation. Here, the overall sequence developed during the transgressive phase where barrier ridge succession is succeeded by the tidal flat succession and the latter, in turn, is succeeded by the estuarine succession. This study resolves the most debated issue of initial marine transgression in the Kachchh Basin during the Cenozoic.

Trace Elements in Marine Sediment and Organisms in the Gulf of Thailand

PubMed Central

Worakhunpiset, Suwalee

2018-01-01

This review summarizes the findings from studies of trace element levels in marine sediment and organisms in the Gulf of Thailand. Spatial and temporal variations in trace element concentrations were observed. Although trace element contamination levels were low, the increased urbanization and agricultural and industrial activities may adversely affect ecosystems and human health. The periodic monitoring of marine environments is recommended in order to minimize human health risks from the consumption of contaminated marine organisms. PMID:29677146

Levels of Cd, Cu, Pb and V in marine sediments in the vicinity of the Single Buoy Moorings (SBM3) at Mina Al Fahal in the Sultanate of Oman.

PubMed

Al-Husaini, Issa; Abdul-Wahab, Sabah; Ahamad, Rahmalan; Chan, Keziah

2014-06-15

Recently in the Sultanate of Oman, there has been a rapid surge of coastal developments. These developments cause metal contamination, which may affect the habitats and communities at and near the coastal region. As a result, a study was conducted to assess the level of metal contamination and its impact on the marine sediments in the vicinity of the Single Buoy Moorings 3 (SBM3) at Mina Al Fahal in the Sultanate of Oman. Marine subtidal sediment samples were collected from six different stations of the SBM3 for the period ranging from June 2009 to April 2010. These samples were then analyzed for their level and distribution of the heavy metals of cadmium (Cd), copper (Cu), lead (Pb) and vanadium (V). Overall, low concentrations of all four heavy metals were measured from the marine sediments, indicating that the marine at SBM3 is of good quality. Copyright © 2014 Elsevier Ltd. All rights reserved.

Distribution and metabolism of quaternary amines in salt marshes

NASA Technical Reports Server (NTRS)

King, Gary M.

1985-01-01

Quaternary amines such as glycine betaine (GBT) are common osmotically active solutes in much of the marine biota. GBT is accumulated by various bacteria, algae, higher plants, invertebrates, and vertebrates in response to salinity or water stresses; in some species, GBT occurs at tens to hundreds of millimolar concentrations and can account for a significant fraction of total nitrogen. Initial studies suggest that GBT is readily converted to two potential methane precursors, trimethylamine (TMA) and acetate, in anoxic sediments. TMA is apparently the most important methane precursor in surface sediments containing sulfate reducing bacteria. In salt marshes, the bulk of the methane formed may be due to the metabolism of TMA rather than other substrates. Current research is focussed on testing this hypothesis and on determining the role of quaternary amino osmoregulatory solutes in methane fluxes from marine environments. Preliminary studies have dealt with several problems: (1) determination of GBT concentrations in the dominant flora and fauna of salt marshes; (2) synthesis of radiolabelled GBT for metabolic studies; and (3) determination of fates of BGT in marine sediments using radiotracers. Both GC and HPLC techniques have been used to assay GBT concentrations in plant and animal tissues. S. alterniflora is probably the only significant source of GBT (and indirectly of methane) since the biomass and distribution of most other species is limited. Current estimates suggest that S. alterniflora GBT could account for most of the methane efflux from salt marshes.

Sedimentary denitrification: Isotope fractionation and its impact on water column nitrate isotopes

NASA Astrophysics Data System (ADS)

Dähnke, K.; Thamdrup, B.

2012-04-01

The global marine nitrogen cycle is constrained by one major source and two processes that act as nitrogen sinks: nitrogen fixation on the one side and denitrification or anammox on the other. These processes with their respective isotope effecst set the marine nitrate 15N-isotope value to a relatively constant average of 5 per mil. This value can be used to better assess the magnitude of these source and sink terms, but the underlying assumption at present is that sedimentary denitrification, a process responsible for approximately one third of global nitrogen removal, has little to no isotope effect on the water column. We tested this hypothesis in sediment incubations, measuring net denitrification and nitrogen and oxygen stable isotope fractionation in surface sediments from the coastal Baltic Sea (Boknis Eck, Northern Germany). We found tremendously high denitrification rates, and regardless of current paradigms assuming little fractionation during sediment denitrification, we measured fractionation factors of 19 per mil for nitrogen and 11 per mil for oxygen in nitrate. These results potentially challenge the current view of fractionation during sedimentary denitrification and imply that nitrogen budget calculation may need to consider this variability. Furthermore, the ratio of fractionation factors for nitrogen and oxygen is distinct from the 1 : 1 ratio otherwise found in marine systems, and suggests that isotope kinetics of sedimentary denitrification might be entirely different from water column denitrification. Acknowledgements: This work was funded by the German Research Foundation (DFG) and in parts by the Danish National Research Foundation.

The effects of Hurricanes Katrina and Rita on seabed polycyclic aromatic hydrocarbon dynamics in the Gulf of Mexico.

PubMed

Mitra, Siddhartha; Lalicata, Joseph J; Allison, Mead A; Dellapenna, Timothy M

2009-06-01

To assess the extent to which Hurricanes Katrina and Rita affected polycyclic aromatic hydrocarbons (PAH) in the Gulf of Mexico (GOM), sediment cores were analyzed in late 2005 from: a shallow shelf, a deeper shelf, and a marsh station. Sediment geochronology, fabric, and geochemistry show that the 2005 storms deposited approximately 10cm of sediment to the surface of a core at 5-12A. Bulk carbon geochemistry and PAH isomers in this top layer suggest that the source of sediment to the top portion of core 5-12A was from a relatively more marine area. Particulate PAHs in the marsh core (04M) appeared unaffected by the storms while sediments in the core from Station 5-1B (deeper shelf) were affected minimally (some possible storm-derived deposition). Substantial amounts of PAH-laden particles may have been displaced from the seabed in shallow areas of the water column in the GOM by these 2005 storms.

Trace Elements in the Marine Sediments of the La Paz Lagoon, Baja California Peninsula, Mexico: Pollution Status in 2013.

PubMed

Pérez-Tribouillier, Habacuc; Shumilin, Evgueni; Rodríguez-Figueroa, Griselda Margarita

2015-07-01

To determine the actual concentrations of trace elements in surface sediments from the La Paz Lagoon, as well as their associations and possible origins, 91 sediment samples were analyzed for more than 50 elements using a combination of ICP-MS and ICP-AES. The results of a principal component analysis are used to distinguish four associative groups within the elements. Natural enrichment of As, Cd and U occurs due to the supply of weathered phosphorites from the El Cien formation located to the north-west of the lagoon. Sediment quality indices for potentially toxic trace elements do not show any probable impact on the biota of the lagoon. Only the concentrations of As in 30 % of the stations and Cu in 20 % of them exceed related effect range low levels. The highest concentration of Pb (36.8 mg kg(-1)) was measured in the sediments near the City of La Paz.

Impact evaluation of the industrial activities in the Bay of Bakar (Adriatic Sea, Croatia): recent benthic foraminifera and heavy metals.

PubMed

Popadić, Adriana; Vidović, Jelena; Cosović, Vlasta; Medaković, Davorin; Dolenec, Matej; Felja, Igor

2013-11-15

The Bay of Bakar is one of the most heavily polluted bays at the Eastern Adriatic. Three major industrial companies potentially endanger the bay. The concentration of major, minor and trace elements in surface sediments from thirteen stations was discussed in relation to the sediment type and foraminiferal assemblages. The distribution of major elements in the bay is influenced by geological nature of surroundings. Heavy metal distribution depends on pollution sources and on amount of mud fraction: fine-grained sediments are enriched by them in comparison with coarse-grained ones. Different sediment quality criteria complicate the pollution assessment in the bay. Heavy metal concentrations generally fall into allowed depositional values for marine environments; only area in front of the coke plant and the City of Bakar harbor is heavily polluted. Stress-tolerant foraminiferal species dominate at stations with higher concentrations of heavy metals and coarse-grained sediments consist of larger number of epifaunal taxa. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

EPA Science Inventory

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

Holocene paleoceanography of Bigo Bay, west Antarctic Peninsula: Connections between surface water productivity and nutrient utilization and its implication for surface-deep water mass exchange

NASA Astrophysics Data System (ADS)

Kim, Sunghan; Yoo, Kyu-Cheul; Lee, Jae Il; Khim, Boo-Keun; Bak, Young-Suk; Lee, Min Kyung; Lee, Jongmin; Domack, Eugene W.; Christ, Andrew J.; Yoon, Ho Il

2018-07-01

Paleoceanographic changes in response to Holocene climate variability in Bigo Bay, west Antarctic Peninsula (WAP) were reconstructed through geochemical, isotopic, sedimentological, and microfossil analysis. Core WAP13-GC47 is composed of 4 lithologic units. Unit 4 was deposited under ice shelf settings. Unit 3 represents the mid-Holocene open marine conditions. Unit 2 indicates lateral sediment transport by a glacier advance during the Neoglacial period. The chronological contrast between the timing of open marine conditions at core WAP13-GC47 (ca. 7060 cal. yr BP at 540 cm) and the ages of calcareous shell fragments (ca. 8500 cal. yr BP) in Unit 2b suggests sediment reworking during the Neoglacial period. Unit 1 was deposited during the Medieval Warm Period (MWP) and the Little Ice Age (LIA). Surface water productivity, represented by biogenic opal and total organic carbon (TOC) concentrations, increased and bulk δ15N (nitrate utilization) decreased during the warmer early to middle Holocene and the MWP. In contrast, surface water productivity decreased with increased bulk δ15N during the colder Neoglacial period and LIA in Bigo Bay. The nitrate utilization was enhanced during cold periods in association with strong surface water stratification resulting from increased sea ice meltwater discharge or proximity to an ice shelf calving front in Bigo Bay. Reduced nitrate utilization during warm periods is related to weak stratification induced by less sea ice meltwater input and stronger Circumpolar Deep Water influence.

Novel carotenol chlorin esters in marine sediments and water column particulate matter

NASA Astrophysics Data System (ADS)

Goericke, Ralf; Shankle, Amy; Repeta, Daniel J.

1999-09-01

Novel esters of carotenols and chlorins (carotenol chlorin esters, CCEs) were found in recent sediments from the California Borderlands, Monterey Bay, and the Peru and Oman margins. The chlorins associated with CCEs were pheophorbide a and pyropheophorbide a, degradation products of chlorophyll a. Isofucoxanthin-dehydrate and isofucoxanthinol-dehydrate and possibly their isomers, degradation products of fucoxanthin, were the only carotenols associated with CCEs. This result is surprising, considering that at least 8 major degradation products of fucoxanthin are present in organic-rich marine sediments. The carotenols of CCEs are likely derived from diatoms as these are the primary source for fucoxanthin in the marine environment. In sediments studied by us, CCEs contributed approximately 10% to total solvent extractable chlorins. The high relative concentrations of CCEs in these sediments suggest that CCEs are an important degradation product of chlorophyll a in some marine environments; a pathway hitherto unrecognized. Off Oman and Southern California we found CCEs in water column suspended particulate matter when diatoms dominated the phytoplankton community. By analogy with sterol chlorin esters, we suggest that CCEs are primarily produced by enzymatically mediated transesterifications in crustaceans grazing on diatoms. We are currently studying if CCEs are biomarkers for the grazing of crustaceans on diatoms, an important pathway of carbon remineralization in the marine environment.

How do natural, uncultivated microbes interact with organic matter? Insights from single cell genomics and metagenomics

NASA Astrophysics Data System (ADS)

Lloyd, K. G.; Bird, J.; Schreiber, L.; Petersen, D.; Kjeldsen, K.; Schramm, A.; Stepanauskas, R.; Jørgensen, B. B.

2013-12-01

Since most of the microbes in marine sediments remain uncultured, little is known about the mechanisms by which these natural communities degrade organic matter (OM). Likewise, little is known about the make-up of labile OM in marine sediments beyond general functional classes such as proteins, carbohydrates, and lipids, measured as monomers. However, microbes have complex interactions with specific polymers within these functional classes, which can be indicated by a microbe's enzymatic toolkit. We found that four single cell genomes of archaea have very different peptidase compositions than four single cells of bacteria, suggesting that archaea and bacteria may play different roles in OM degradation. We also found that predicted extracellular cysteine peptidases, which require chemically reducing conditions, were common in IMG database metagenomes from marine sediments, and absent in those from seawater. This suggests that the pathways, and not just the rates, of OM degradation may differ between seawater and sediments. By comparing enzyme classes in different organisms, or in different types of marine environments, we present an emerging view of the microbial potential for specific carbon remineralization pathways in marine sediments. In addition, the methods we present hold promise for characterizing OM degradation in any environment where genomic information is available.

Trawling-induced alterations of deep-sea sediment accumulation rates during the Anthropocene

NASA Astrophysics Data System (ADS)

Puig, P.; Paradis, S.; Masque, P.; Martin, J.; Juan, X.; Palanques, A.

2015-12-01

Commercial bottom trawling causes direct physical disturbance of the marine sedimentary environments by scraping and ploughing the seabed, generating periodic resuspension of surface sediments. However, the quantification of the sediment that is removed by trawling and exported across the continental margin remains largely unaddressed, and the preservation of the signal of such impacts in the geological record have been mostly overlooked. The analysis of sediment cores collected along the Catalan margin (NW Mediterranean) has allowed evaluating the contribution of this anthropogenic activity to the present-day sediment dynamics. Sediment cores at intensively trawled sites are characterized by over-consolidated sediments with lower 210Pb surface concentrations and inventories that indicate widespread erosion of recent sedimentary deposits. In turn, combined 210Pb and 137Cs chronologies indicate a significant increase of sediment accumulation rates within submarine canyon environments since the 1970s, coincidently with a strong impulse in the industrialization of the trawling fleets of this region. Two sampling sites that exhibited high sediment accumulation rates (0.6-0.7 cm/y) were reoccupied 1-2 decades after the first studies and revealed a second and even larger increase of sediment accumulation rates (>2 cm/y) occurring at the beginning of the XXI century. This recent change has been attributed to a preferential displacement of the trawling fleet towards fishing grounds surrounding submarine canyons and, also, to technical improvements in trawling vessels, presumably related to financial subsidies provided to the fishing sector. The alteration of sediment accumulation rates described in this continental margin may occur in many regions of the World's oceans given the wide geographical distribution of this human activity, and therefore, it could represent a potential marker of the Anthropocene in deep-sea environments.

Norwegian monitoring (1990-2015) of the marine environment around the sunken nuclear submarine Komsomolets.

PubMed

Gwynn, Justin P; Heldal, Hilde Elise; Flo, Janita K; Sværen, Ingrid; Gäfvert, Torbjörn; Haanes, Hallvard; Føyn, Lars; Rudjord, Anne Liv

2018-02-01

Norway has monitored the marine environment around the sunken Russian nuclear submarine Komsomolets since 1990. This study presents an overview of 25 years of Norwegian monitoring data (1990-2015). Komsomolets sank in 1989 at a depth of 1680 m in the Norwegian Sea while carrying two nuclear torpedoes in its armament. Subsequent Soviet and Russian expeditions to Komsomolets have shown that releases from the reactor have occurred and that the submarine has suffered considerable damage to its hulls. Norwegian monitoring detected 134 Cs in surface sediments around Komsomolets in 1993 and 1994 and elevated activity concentrations of 137 Cs in bottom seawater between 1991 and 1993. Since then and up to 2015, no increased activity concentrations of radionuclides above values typical for the Norwegian Sea have been observed in any environmental sample collected by Norwegian monitoring. In 2013 and 2015, Norwegian monitoring was carried out using an acoustic transponder on the sampling gear that allowed samples to be collected at precise locations, ∼20 m from the hull of Komsomolets. The observed 238 Pu/ 239,240 Pu activity ratios and 240 Pu/ 239 Pu atom ratios in surface sediments sampled close to Komsomolets in 2013 did not indicate any releases of Pu isotopes from reactor or the torpedo warheads. Rather, these values probably reflect the overprinting of global fallout ratios with fluxes of these Pu isotopes from long-range transport of authorised discharges from nuclear reprocessing facilities in Northern Europe. However, due to the depth at which Komsomolets lies, the collection of seawater and sediment samples in the immediate area around the submarine using traditional sampling techniques from surface vessels is not possible, even with the use of acoustic transponders. Further monitoring is required in order to have a clear understanding of the current status of Komsomolets as a potential source of radioactive contamination to the Norwegian marine environment. Such monitoring should involve the use of ROVs or submersibles in order to obtain samples next to and within the different compartments of the submarine. Copyright © 2017 Elsevier Ltd. All rights reserved.

Organic pollutants in the coastal environment off San Diego, California. 1: Source identification and assessment by compositional indices of polycyclic aromatic hydrocarbons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeng, E.Y.; Vista, C.L.

1997-02-01

Samples collected in January and June 1994 from the Point Loma Wastewater Treatment Plant (PLWTP) effluent, Tijuana River runoff, and microlayer, sediment trap, and surface sediment at several locations adjacent to the PLWTP outfall, mouth of the Tijuana River, and San Diego Bay were analyzed in an attempt to identify and assess the sources of hydrocarbon inputs into the coastal marine environment off San Diego. Several compositional indices of polycyclic aromatic hydrocarbons (PAHs), for example, alkyl homologue distributions, parent compound distributions, and other individual PAH ratios, were used to identify the sources of PAHs. Partially due to the decline ofmore » PAH emission from the PLWTP outfall, PAHs found in the sea surface microlayer, sediments, and water column particulates near the PLWTP outfall were predominantly derived from nonpoint sources. The sea microlayer near the mouth of the Tijuana River appeared to accumulate enhanced amounts of PAHs and total organic carbon and total nitrogen, probably discharged from the river, although they were in extremely low abundance in the sediments at the same location. Surprisingly, PAHs detected in the microlayer and sediments in San Diego Bay were mainly derived from combustion sources rather than oil spills, despite the heavy shipping activities in the area.« less

Buried Alive: The Behavioural Response of the Mussels, Modiolus modiolus and Mytilus edulis to Sudden Burial by Sediment

PubMed Central

Hutchison, Zoë L.; Hendrick, Vicki J.; Burrows, Michael T.; Wilson, Ben; Last, Kim S.

2016-01-01

Sedimentation in the sea occurs through natural processes, such as wave and tidal action, which can be exacerbated during storms and floods. Changes in terrestrial land use, marine aggregate extraction, dredging, drilling and mining are known to result in substantial sediment deposition. Research suggests that deposition will also occur due to the modern development of marine renewable energy. The response to individual burial under three depths of sediment, three sediment fractions and five burial durations was investigated in two mussel species, Modiolus modiolus and Mytilus edulis in specialist mesocosms. Both mussel species showed substantial mortality, which increased with duration of burial and burial by finer sediment fractions. M. modiolus was better able to survive short periods of burial than M. edulis, but at longer durations mortality was more pronounced. No mortality was observed in M. modiolus in burial durations of eight days or less but by 16 days of burial, over 50% cumulative mortality occurred. Under variable temperature regimes, M. edulis mortality increased from 20% at 8°C to over 60% at 14.5 and 20°C. Only M. edulis was able to emerge from burial, facilitated by increased byssus production, laid mostly on vertical surfaces but also on sediment particles. Emergence was higher from coarse sediment and shallow burials. Byssus production in M. edulis was not related to the condition index of the mussels. Results suggest that even marginal burial would result in mortality and be more pronounced in warm summer periods. Our results suggest that in the event of burial, adult M. modiolus would not be able to emerge from burial unless local hydrodynamics assist, whereas a small proportion of M. edulis may regain contact with the sediment water interface. The physiological stress resulting in mortality, contribution of local hydrodynamics to survival and other ecological pressures such as mussels existing in aggregations, are discussed. PMID:26982582

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

PubMed Central

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

2015-01-01

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

From gullies to mountain belts: A review of sediment budgets at various scales

NASA Astrophysics Data System (ADS)

Hinderer, Matthias

2012-12-01

This paper reviews the state of the art in the concept as well as in the application of sediment budgets in sedimentary research. Sediments are a product of mass dispersal at the Earth surface and take part in global cycles. Sediment budgets aim at quantifying this mass transfer based on the principle of mass conservation and are the key to determine ancient fluxes of solid matter at the earth surface. This involves fundamental questions about the interplay of uplift, climate and denudation in mountain belts and transfer of sediments from the continents to the oceans as well as applied issues such as soil and gully erosion, reservoir siltation, and coastal protection. First, after introducing basic concepts, relevant scales and methodologies, the different components of Quaternary routing systems from erosion in headwaters, river systems, glacial and paraglacial systems, lakes, deltas, estuaries, coasts, shelves, epicontinental seas, and deep-sea fans are discussed in terms of their sediment budget. Most suitable are sedimentologically closed or semi-closed depositional environments e.g. alluvial fans, lakes, deltas and deep-sea fans. In a second step, the dynamics of passive, active, and collisional tectonic settings and sediment budgets in related sedimentary basins are explored and new concepts of sediment portioning at large geodynamic scales are introduced. Ancient routing systems are more or less incomplete and may be intensively fragmented or destroyed in active tectonic settings. In terms of sedimentary basin types, rifts, intracontinental and epicontinental settings are preferred objects of sediment budgets, because of their persistence and relatively simple overall sedimentary architecture. However, closing basins, such as foreland, forearc, retroarc, piggy-back and wedge-top basins may provide excellent snapshots of orogenic sediment fluxes. In a third step, the large long-lived routing systems of the Amazon, the Ganges-Brahmaputra, and the Rhine are reviewed. For each system estimates of either sediment volumes (mass) or sediment fluxes of continental and marine subsystems have been compiled in order to receive a complete routing in terms of mass conservation for specific time periods since the Late Glacial Maximum as well as the Cenozoic. Following lessons can be taken from these case studies: (i) depositional centers and fluxes show strong shifts in space and time and call for caution when simply looking at subsystems, (ii) the response times of these large systems are within the Milankovich time interval, thus lower than predicted from diffusion models, (iii) cyclic routing of sediments in continental basins is much more dominated by climate (human) control than by eustacy, and (iv) at long time scales, ultimate sinks win over intermittent storage. It is concluded from this review that the quantitative understanding of global sediment cycling over historic and geologic time and its response to allogenic forcing is still in its infancy and further research is needed towards a holistic view of sediment routing systems at various temporal and spatial scales and their coupling with global biogeochemical cycles. This includes (i) to better determine response times of large routing systems by linking Quaternary with Cenozoic sediment budgets and continental with marine sub-systems, (ii) to combine advanced provenance techniques with sediment budgets in order to reconstruct ancient systems, (iii) to study sediment partitioning at the basin scale, (iv) to reconcile continental, supply-dominated sequence stratigraphy with the eustatic-dominated marine concept, and (iv) to account for non-actualism of ancient systems with respect to their erosion and transport mode, in particular, during glaciations and pronounced arid intervals. Glacial and eolian sediment routing may cross over hydrologic boundaries of drainage basins, thus challenging the principle of mass conservation.

Sulphate reduction and nitrogen fixation rates associated with roots, rhizomes and sediments from Zostera noltii and Spartina maritima meadows.

PubMed

Nielsen, L B; Finster, K; Welsh, D T; Donelly, A; Herbert, R A; de Wit, R; Lomstein, B A

2001-01-01

Sulphate reduction rates (SRR) and nitrogen fixation rates (NFR) associated with isolated roots, rhizomes and sediment from the rhizosphere of the marine macrophytes Zostera noltii and Spartina maritima, and the presence and distribution of Bacteria on the roots and rhizomes, were investigated. Between 1% and 3% of the surface area of the roots and rhizomes of both macrophytes were colonized by Bacteria. Bacteria on the surfaces of S. maritima roots and rhizomes were evenly distributed, while the distribution of Bacteria on Z. noltii roots and rhizomes was patchy. Root- and rhizome-associated SRR and NFR were always higher than rates in the bulk sediment. In particular, nitrogen fixation associated with the roots and rhizomes was 41-650-fold higher than in the bulk sediment. Despite the fact that sulphate reduction was elevated on roots and rhizomes compared with bulk sediment, the contribution of plant-associated sulphate reduction to overall sulphate reduction was small (< or =11%). In contrast, nitrogen fixation associated with the roots and rhizomes accounted for 31% and 91% of the nitrogen fixed in the rhizosphere of Z. noltii and S. maritima respectively. In addition, plant-associated nitrogen fixation could supply 37-1,613% of the nitrogen needed by the sulphate-reducing community. Sucrose stimulated nitrogen fixation and sulphate reduction significantly in the root and rhizome compartments of both macrophytes, but not in the bulk sediment.

Nitrogen cycling in 2.7 Ga oceans

NASA Astrophysics Data System (ADS)

Yang, J.; Zerkle, A.; Grassineau, N.; Nisbet, E.; Mettam, C.; Izon, G. J.; Morag, H.; Anthony, M.; Newton, J.; Boyce, A.

2016-12-01

A growing body of geochemical evidence suggests that localized oxygenation of the surface earth must have begun much earlier than the GOE ( 2.4 Ga). This could have triggered the emergence of the aerobic biogeochemical cycle of nitrogen (N), an essential nutrient for all organisms. However, the timing of this revolutionary transition is poorly known. Some sediments from 2.7 Ga possess exceptionally high enrichment of 15N. Whether these values are linked to the onset of the aerobic N cycle[1], or reflective of alkaline lakes on land[2], has been in dispute. To explore this, we are investigating one of the best-preserved unambiguously marine Achaean successions from the Belingwe Greenstone Belt, in Zimbabwe. We are focusing on nearly pristine sediments from the 2.7 Ga Manjeri Formation, which span both shallow and deep-water environments, preserving organic-rich shales and some of the oldest and most well-preserved stromatolites. The depositional conditions for this succession are further constrained by iron speciation data and sulfur isotopes, which show a redox transition from ferruginous to oxic environments from older to younger sediments. Nitrogen isotopes in these sediments will constrain the global nature of the extremely 15N-enriched values, and test hypotheses for the Neoarchean nitrogen cycle in a non-disputed marine setting. [1] Thomazo et al. (2011) Geobiology; [2] Stüeken et al. (2015) EPSL.

Depositional environments and processes in Upper Cretaceous nonmarine and marine sediments, Ocean Point dinosaur locality, North Slope, Alaska

USGS Publications Warehouse

Phillips, R.L.

2003-01-01

A 178-m-thick stratigraphic section exposed along the lower Colville River in northern Alaska, near Ocean Point, represents the uppermost part of a 1500 m Upper Cretaceous stratigraphic section. Strata exposed at Ocean Point are assigned to the Prince Creek and Schrader Bluff formations. Three major depositional environments are identified consisting, in ascending order, of floodplain, interdistributary-bay, and shallow-marine shelf. Nonmarine strata, comprising the lower 140 m of this section, consist of fluvial distributaries, overbank sediments, tephra beds, organic-rich beds, and vertebrate remains. Tephras yield isotopic ages between 68 and 72.9 Ma, generally consistent with paleontologic ages of late Campanian-Maastrichtian determined from dinosaur remains, pollen, foraminifers, and ostracodes. Meandering low-energy rivers on a low-gradient, low-relief floodplain carried a suspended-sediment load. The rivers formed multistoried channel deposits (channels to 10 m deep) as well as solitary channel deposits (channels 2-5 m deep). Extensive overbank deposits resulting from episodic flooding formed fining-upward strata on the floodplain. The fining-upward strata are interbedded with tephra and beds of organic-rich sediment. Vertical-accretion deposits containing abundant roots indicate a sheet flood origin for many beds. Vertebrate and nonmarine invertebrate fossils along with plant debris were locally concentrated in the floodplain sediment. Deciduous conifers as well as abundant wetland plants, such as ferns, horsetails, and mosses, covered the coastal plain. Dinosaur skeletal remains have been found concentrated in floodplain sediments in organic-rich bone beds and as isolated bones in fluvial channel deposits in at least nine separate horizons within a 100-m-thick interval. Arenaceous foraminifers in some organic-rich beds and shallow fluvial distributaries indicate a lower coastal plain environment with marginal marine (bay) influence. Marginal marine strata representing interdistributary bay deposits overlie the nonmarine beds and comprise about 15 m of section. Extensive vegetated sand flats, shoals, and shallow channels overlain by shallow bay deposits (less than 7 m deep), containing storm-generated strata characterize the marginal marine beds. Abundant bioturbation and roots characterize the stratigraphic lowest bay deposits; bioturbated sediment, pelecypods, barnacles, and benthic microfossils are found in the overlying bay storm deposits. The sediments abruptly change upward from hummocky cross-stratified bay deposits to a muddy marsh deposit containing shallow organic-rich channels to prograding nonmarine to marginal marine beds. Transgressive, abundantly fossiliferous shallow-marine strata more than 13 m thick comprise the uppermost exposures at Ocean Point. The marine beds overlie nonmarine and bay strata and represent an environment dominated episodically by storms. The age of the marginal marine and marine beds is late Maastrichtian based on pollen. ?? 2003 Elsevier Ltd. All rights reserved.

Salinity shifts in marine sediment: Importance of number of fluctuation rather than their intensities on bacterial denitrifying community.

PubMed

Zaghmouri, Imen; Michotey, Valerie D; Armougom, Fabrice; Guasco, Sophie; Bonin, Patricia C

2018-05-01

The sensitivity of denitrifying community to salinity fluctuations was studied in microcosms filled with marine coastal sediments subjected to different salinity disturbances over time (sediment under frequent salinity changes vs sediment with "stable" salinity pattern). Upon short-term salinity shift, denitrification rate and denitrifiers abundance showed high resistance whatever the sediment origin is. Denitrifying community adapted to frequent salinity changes showed high resistance when salinity increases, with a dynamic nosZ relative expression level. Marine sediment denitrifying community, characterized by more stable pattern, was less resistant when salinity decreases. However, after two successive variations of salinity, it shifted toward the characteristic community of fluctuating conditions, with larger proportion of Pseudomonas-nosZ, exhibiting an increase of nosZ relative expression level. The impact of long-term salinity variation upon bacterial community was confirmed at ribosomal level with a higher percentage of Pseudomonas and lower proportion of nosZII clade genera. Copyright © 2018 Elsevier Ltd. All rights reserved.

Marine dredged sediments as new materials resource for road construction.

PubMed

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

2008-01-01

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

Use of 16S rRNA-targeted oligonucleotide probes to investigate the distribution of sulphate-reducing bacteria in estuarine sediments.

PubMed

Purdy, K J.; Nedwell, D B.; Embley, T M.; Takii, S

2001-07-01

The distribution of sulphate-reducing bacteria (SRBs) in three anaerobic sediments, one predominantly freshwater and low sulphate and two predominantly marine and high sulphate, on the River Tama, Tokyo, Japan, was investigated using 16S rRNA-targeted oligonucleotide probes. Hybridisation results and sulphate reduction measurements indicated that SRBs are a minor part of the bacterial population in the freshwater sediments. Only Desulfobulbus and Desulfobacterium were detected, representing 1.6% of the general bacterial probe signal. In contrast, the SRB community detected at the two marine-dominated sites was larger and more diverse, representing 10-11.4% of the bacterial signal and with Desulfobacter, Desulfovibrio, Desulfobulbus and Desulfobacterium detected. In contrast to previous reports our results suggest that Desulfovibrio may not always be the most abundant SRB in anaerobic sediments. Acetate-utilising Desulfobacter were the dominant SRB in the marine-dominated sediments, and Desulfobulbus and Desulfobacterium were active in low-sulphate sediments, where they may utilise electron acceptors other than sulphate.

Impacts of pollution derived from ship wrecks on the marine environment on the basis of s/s "Stuttgart" (Polish coast, Europe).

PubMed

Rogowska, Justyna; Wolska, Lidia; Namieśnik, Jacek

2010-11-01

In 1943 the German hospital ship s/s Stuttgart (Lazaretschiff "C") was sunk close to the port of Gdynia (Gulf of Gdańsk - Polish coast). This and other actions (undertaken after the war to remove the wreck) led to pollution of the sea bottom with oil derivatives. During our studies (2009) 11 surface sediment and water samples were collected as well as sediment core samples at 4 locations in order to determine the concentration levels of priority pollutants belonging to polycyclic aromatic hydrocarbons (PAH) and polychlorinated biphenyls (PCB). The concentrations of 16 PAH and 7 PCB were analysed with GC-MS. ΣPAH varied between 11.54 ± 0.39 and 206.7 ± 6.5mg/kg dry weight in the surface sediments, and from 0.686 ± 0.026 to 1291 ± 53 mg/kg dry weight in the core samples. Contamination in the core samples collected may reach a depth of at least 230-240 cm (deepest sample studied). The PAH-group profiles in all surface sediment samples suggest a pyrolytic source of PAH, while the results obtained for core samples indicate a mixed pattern of pyrolytic and petrogenic inputs of PAH. Results obtained may suggest also that fuel residues being present at sea bottom is not crude oil derived but results from coal processing (synthetic fuel). The sum of PCB in surface sediments ranged from 0.761 ± 0.068 to 6.82 ± 0.28 μg/kg dry weight (except for sampling point W2, where ΣPCB was 108.8 ± 4.4 μg/kg dry weight). The strong correlation between PAH and PCB levels, and the fact that PCB are present only in the surface sediments, suggest that the compounds in these sediments got there as a result of emission from urban areas, entering the aquatic environment via atmospheric deposition. PCB levels in the sediment core samples were generally very low and in most cases did not exceed the method quantification limit. Copyright © 2010 Elsevier B.V. All rights reserved.

Marine pollution in the Libyan coastal area: Environmental and risk assessment.

PubMed

Bonsignore, Maria; Salvagio Manta, Daniela; Al-Tayeb Sharif, Ehab A; D'Agostino, Fabio; Traina, Anna; Quinci, Enza Maria; Giaramita, Luigi; Monastero, Calogera; Benothman, Mohamed; Sprovieri, Mario

2018-03-01

A comprehensive assessment of the potential adverse effects on environment and human health generated by the inputs of chemicals from the most important Libyan petrochemical plant is presented. Ecotoxicological risk associated with the presence of As, Hg, Ni, Zn and PAHs in marine sediments is low or moderate, with a probability of toxicity for ecosystem <9% and <20% for heavy metals and PAHs respectively. However, surface sediments result strongly enriched in Hg and As of anthropogenic origin. Investigation of metals in fish allowed to assess potential risks for human populations via fish intake. Target hazard quotients values indicate potential risk associated to toxic metals exposure by fish consumption and lifetime cancer risk (TR) values highlight a potential carcinogen risk associated to As intake. Noteworthy, the presented results provide an unprecedented environmental dataset in an area where the availability of field data is very scant, for a better understanding of anthropogenic impacts at Mediterranean scale. Copyright © 2018 Elsevier Ltd. All rights reserved.

Origin and fate of sedimentary organic matter in the northern Bay of Bengal during the last 18 ka

NASA Astrophysics Data System (ADS)

Contreras-Rosales, L. A.; Schefuß, E.; Meyer, V.; Palamenghi, L.; Lückge, A.; Jennerjahn, T. C.

2016-11-01

The Northern Bay of Bengal (NBoB) is a globally important region for deep-sea organic matter (OM) deposition due to massive fluvial discharge from the Ganges-Brahmaputra-Meghna (G-B-M) rivers and moderate to high surface productivity. Previous studies have focused on carbon burial in turbiditic sediments of the Bengal Fan. However, little is known about the storage of carbon in pelagic and hemipelagic sediments of the Bay of Bengal over millennial time scales. This study presents a comprehensive history of OM origin and fate as well as a quantification of carbon sediment storage in the Eastern Bengal Slope (EBS) during the last 18 ka. Bulk organic proxies (TOC, TIC, TN, δ13CTOC, δ15NTN) and content and composition of total hydrolysable amino acids (THAA) in a sediment core (SO188-342KL) from the EBS were analyzed. Three periods of high OM accumulation were identified: the Late Glacial (LG), the Bölling/Alleröd (B/A), and the Early Holocene Climatic Optimum (EHCO). Lower eustatic sea level before 15 ka BP allowed a closer connection between the EBS and the fluvial debouch, favoring high terrestrial OM input to the core site. This connection was progressively lost between 15 and 7 ka BP as sea level rose to its present height and terrestrial OM input decreased considerably. Export and preservation of marine OM was stimulated during periods of summer monsoon intensification (B/A and EHCO) as a consequence of higher surface productivity enhanced by cyclonic-eddy nutrient pumping and fluvial nutrient delivery into the photic zone. Changes in the THAA composition indicate that the marine plankton community structure shifted from calcareous-dominated before 13 ka BP to siliceous-dominated afterwards. They also indicate that the relative proportion of marine versus terrestrial OM deposited at site 342KL was primarily driven by relative sea level and enlarged during the Holocene. The ballasting effect of lithogenic particles during periods of high coastal proximity and/or enhanced fluvial discharge promoted the export and preservation of OM. The high organic carbon accumulation rates in the EBS during the LG (18-17 ka BP) were 5-fold higher than at present and comparable to those of glacial upwelling areas. Despite the differences in sediment and OM transport and storage among the Western and Eastern sectors of the NBoB, this region remains important for global carbon sequestration during sea level low-stands. In addition, the summer monsoon was a key promotor of terrestrial and marine OM export to the deep-ocean, highlighting its relevance as regulator of the global carbon budget.

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

NASA Technical Reports Server (NTRS)

Acker, James G.

2006-01-01

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

Loess Plateau storage of Northeastern Tibetan Plateau-derived Yellow River sediment

PubMed Central

Nie, Junsheng; Stevens, Thomas; Rittner, Martin; Stockli, Daniel; Garzanti, Eduardo; Limonta, Mara; Bird, Anna; Andò, Sergio; Vermeesch, Pieter; Saylor, Joel; Lu, Huayu; Breecker, Daniel; Hu, Xiaofei; Liu, Shanpin; Resentini, Alberto; Vezzoli, Giovanni; Peng, Wenbin; Carter, Andrew; Ji, Shunchuan; Pan, Baotian

2015-01-01

Marine accumulations of terrigenous sediment are widely assumed to accurately record climatic- and tectonic-controlled mountain denudation and play an important role in understanding late Cenozoic mountain uplift and global cooling. Underpinning this is the assumption that the majority of sediment eroded from hinterland orogenic belts is transported to and ultimately stored in marine basins with little lag between erosion and deposition. Here we use a detailed and multi-technique sedimentary provenance dataset from the Yellow River to show that substantial amounts of sediment eroded from Northeast Tibet and carried by the river's upper reach are stored in the Chinese Loess Plateau and the western Mu Us desert. This finding revises our understanding of the origin of the Chinese Loess Plateau and provides a potential solution for mismatches between late Cenozoic terrestrial sedimentation and marine geochemistry records, as well as between global CO2 and erosion records. PMID:26449321

Using a forensic science approach to minimize environmental contamination and to identify microfibres in marine sediments.

PubMed

Woodall, Lucy C; Gwinnett, Claire; Packer, Margaret; Thompson, Richard C; Robinson, Laura F; Paterson, Gordon L J

2015-06-15

There is growing evidence of extensive pollution of the environment by microplastic, with microfibres representing a large proportion of the microplastics seen in marine sediments. Since microfibres are ubiquitous in the environment, present in the laboratory air and water, evaluating microplastic pollution is difficult. Incidental contamination is highly likely unless strict control measures are employed. Here we describe methods developed to minimize the amount of incidental post-sampling contamination when quantifying marine microfibre pollution. We show that our protocol, adapted from the field of forensic fibre examination, reduces fibre abundance by 90% and enables the quick screening of fibre populations. These methods therefore allow an accurate estimate of microplastics polluting marine sediments. In a case study from a series of samples collected on a research vessel, we use these methods to highlight the prevalence of microfibres as marine microplastics. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Dynamic modeling of environmental risk associated with drilling discharges to marine sediments.

PubMed

Durgut, İsmail; Rye, Henrik; Reed, Mark; Smit, Mathijs G D; Ditlevsen, May Kristin

2015-10-15

Drilling discharges are complex mixtures of base-fluids, chemicals and particulates, and may, after discharge to the marine environment, result in adverse effects on benthic communities. A numerical model was developed to estimate the fate of drilling discharges in the marine environment, and associated environmental risks. Environmental risk from deposited drilling waste in marine sediments is generally caused by four types of stressors: oxygen depletion, toxicity, burial and change of grain size. In order to properly model these stressors, natural burial, biodegradation and bioturbation processes were also included. Diagenetic equations provide the basis for quantifying environmental risk. These equations are solved numerically by an implicit-central differencing scheme. The sediment model described here is, together with a fate and risk model focusing on the water column, implemented in the DREAM and OSCAR models, both available within the Marine Environmental Modeling Workbench (MEMW) at SINTEF in Trondheim, Norway. Copyright © 2015 Elsevier Ltd. All rights reserved.

The geochemistry of coprostanol in waters and surface sediments from Narragansett Bay

NASA Astrophysics Data System (ADS)

LeBlanc, Lawrence A.; Latimer, James S.; Ellis, John T.; Quinn, James G.

1992-05-01

A geochemical study of coprostanol (5β-Cholestan-3β-ol) was undertaken, to examine the transport and fate of a compound of moderate polarity and reactivity in the marine environment, and also because of the interest in coprostanol for use as a sewage tracer. During 1985-86, 20 sites in Narragansett Bay, including the major point sources and rivers discharging into the bay estuary, were sampled at four different times. In addition, surface sediments from 26 stations in the bay were collected. The large number and diversity of samples allowed for an assessment of major inputs of sewage into the bay as well as the recent fate of sewage-derived particles in surface sediments. Results from the study revealed that 50% of the total particulate coprostanol entering the bay was discharged into the Providence River, primarily due to inputs from the wastewater treatment facility (WWTF) at Fields Point, as well as input from the Pawtuxet and Blackstone Rivers. In the lower bay, the Newport WWTF was the largest single source of coprostanol (37% of the total particulate coprostanol) to the bay. Effluent concentrations of coprostanol from secondary WWTFs were consistently lower than those of primary treatment facilities, demonstrating the usefulness of corporstanol as an indicator of treatment plant efficiency. The distribution of coprostanol in waters and surface sediments showed a gradient of decreasing concentration downbay. When coprostanol concentrations in surface sediments were normalized to organic carbon (OC) concentrations, elevated levels were seen only in the Providence River, with a more or less even distribution throughout the rest of the bay. Results also suggest that coprostanol degrades more rapidly in the water column compared to the petroleum hydrocarbons (PHCs), polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs), however, it is relatively stable once it is buried in the sediments. Coprostanol concentrations in waters (0·02-0·22 μg 1 -1) and surface sediments (0·22-33 μg g -1) were as high or higher than values reported in the literature, indicating that the estuary is impacted by sewage.

Distribution and origins of n-alkanes, hopanes, and steranes in rivers and marine sediments from Southwest Caspian coast, Iran: implications for identifying petroleum hydrocarbon inputs.

PubMed

Shirneshan, Golshan; Bakhtiari, Alireza Riyahi; Memariani, Mahmoud

2016-09-01

The occurrence of n-alkanes and biomarkers (hopane and sterane) in surface sediments from Southwestern coasts of Caspian Sea and 28 rivers arriving to this lake, determined with a gas chromatography-mass spectrometry method, was used to assess the impacts of anthropogenic activities in the studied area. The concentrations of total n-alkanes (Σ21 n-alkane) in costal and riverine sediments varied from 249.2 to 3899.5 and 56 to 1622.4 μg g(-1), respectively. An evaluation of the source diagnostic indices indicated that petroleum related sources (petrogenic) were mainly contributed to n-alkanes in costal and most riverine sediments. Only the hydrocarbons in sediment of 3 rivers were found to be mainly of biogenic origin. Principal component analysis using hopane diagnostic ratios in costal and riverine sediments, and Anzali, Turkmenistan, and Azerbaijan oils were used to identify the sources of hydrocarbons in sediments. It was indicated that the anthropogenic contributions in most of the costal sediment samples are dominated with inputs of oil spills from Turkmenistan and Azerbaijan countries.

Microbial community assembly and evolution in subseafloor sediment.

PubMed

Starnawski, Piotr; Bataillon, Thomas; Ettema, Thijs J G; Jochum, Lara M; Schreiber, Lars; Chen, Xihan; Lever, Mark A; Polz, Martin F; Jørgensen, Bo B; Schramm, Andreas; Kjeldsen, Kasper U

2017-03-14

Bacterial and archaeal communities inhabiting the subsurface seabed live under strong energy limitation and have growth rates that are orders of magnitude slower than laboratory-grown cultures. It is not understood how subsurface microbial communities are assembled and whether populations undergo adaptive evolution or accumulate mutations as a result of impaired DNA repair under such energy-limited conditions. Here we use amplicon sequencing to explore changes of microbial communities during burial and isolation from the surface to the >5,000-y-old subsurface of marine sediment and identify a small core set of mostly uncultured bacteria and archaea that is present throughout the sediment column. These persisting populations constitute a small fraction of the entire community at the surface but become predominant in the subsurface. We followed patterns of genome diversity with depth in four dominant lineages of the persisting populations by mapping metagenomic sequence reads onto single-cell genomes. Nucleotide sequence diversity was uniformly low and did not change with age and depth of the sediment. Likewise, there was no detectable change in mutation rates and efficacy of selection. Our results indicate that subsurface microbial communities predominantly assemble by selective survival of taxa able to persist under extreme energy limitation.

Archaeal community diversity and abundance changes along a natural salinity gradient in estuarine sediments

PubMed Central

Webster, Gordon; O'Sullivan, Louise A.; Meng, Yiyu; Williams, Angharad S.; Sass, Andrea M.; Watkins, Andrew J.; Parkes, R. John; Weightman, Andrew J.

2014-01-01

Archaea are widespread in marine sediments, but their occurrence and relationship with natural salinity gradients in estuarine sediments is not well understood. This study investigated the abundance and diversity of Archaea in sediments at three sites [Brightlingsea (BR), Alresford (AR) and Hythe (HY)] along the Colne Estuary, using quantitative real-time PCR (qPCR) of 16S rRNA genes, DNA hybridization, Archaea 16S rRNA and mcrA gene phylogenetic analyses. Total archaeal 16S rRNA abundance in sediments were higher in the low-salinity brackish sediments from HY (2–8 × 107 16S rRNA gene copies cm−3) than the high-salinity marine sites from BR and AR (2 × 104–2 × 107 and 4 × 106–2 × 107 16S rRNA gene copies cm−3, respectively), although as a proportion of the total prokaryotes Archaea were higher at BR than at AR or HY. Phylogenetic analysis showed that members of the ‘Bathyarchaeota’ (MCG), Thaumarchaeota and methanogenic Euryarchaeota were the dominant groups of Archaea. The composition of Thaumarchaeota varied with salinity, as only ‘marine’ group I.1a was present in marine sediments (BR). Methanogen 16S rRNA genes from low-salinity sediments at HY were dominated by acetotrophic Methanosaeta and putatively hydrogentrophic Methanomicrobiales, whereas the marine site (BR) was dominated by mcrA genes belonging to methylotrophic Methanococcoides, versatile Methanosarcina and methanotrophic ANME-2a. Overall, the results indicate that salinity and associated factors play a role in controlling diversity and distribution of Archaea in estuarine sediments. PMID:25764553

Investigation into spore coat properties for the rapid identification of endospores in marine sediments

NASA Astrophysics Data System (ADS)

Rattray, J. E.; Chakraborty, A.; Bernard, B. B.; Brooks, J.; Hubert, C. R.

2017-12-01

Understanding the sediment biogeography of dormant marine thermophilic bacterial endospores (thermospores) has the potential to assist locating and characterising working petroleum systems. The presence of thermospores in cold ocean environments suggests that distribution occurs via hydrocarbon seepage from thermally active reservoirs. Low abundance and endospore coat physiology mean nucleic acid based techniques have limited success for in situ detection of thermospores. Alternative rapid analytical methods are needed so we investigated using the Schaeffer-Fulton (malachite green and safranin) and DAPI (4',6-diamidino-2-phenylindole) staining techniques on thermospores from cultures and marine sediments. Sediment samples from 111 locations in the Eastern Gulf of Mexico (100 to 3300 m water depth; 6 to 600 km apart) were incubated at high temperature, followed by construction of 16S rRNA gene amplicon libraries (V3-V4 region; Illumina MiSeq) revealing enrichment of species-level thermospore OTUs. A sulfate reducing bacterium from site EGM080 was purified and classified based on its rRNA gene sequence as Desulfotomaculum geothermicum. Prior to thermospore staining the culture was kept in the death/ decline phase for 16 weeks to promote sporulation. Samples of D. geothermicum and the source marine sediment were fixed, stained then analysed using brightfield, phase contrast or fluorescence microscopy. Thermospores in pure culture were identified using phase contrast but were difficult to observe in the sediment sample due to particle aggregation. The Schaeffer-Fulton technique aided thermospore identification in a complex sediment sample matrix as thermospores were stained bright green, and also revealed that there were only spores and no (red stained) vegetative cells in the culture. Treatment with DAPI gave dull fluorescing cells but also provided insight into the behaviour of thermospores in sediment suspensions. Spores in the culture medium were free floating but in the sediment suspension they were only attached to aggregated fluorescing material. Further investigation into thermospore association with bioparticles could further our understanding of the passive dispersal of spores in marine environments.

Impact of water depth on the distribution of iGDGTs in the surface sediments from the northern South China Sea: applicability of TEX86 in marginal seas

NASA Astrophysics Data System (ADS)

Chen, Jiali; Hu, Pengju; Li, Xing; Yang, Yang; Song, Jinming; Li, Xuegang; Yuan, Huamao; Li, Ning; Lü, Xiaoxia

2018-03-01

The TEX 86 H paleothermometer on the base of isoprenoid glycerol dialkyl glycerol tetraethers (iGDGTs) has been widely applied to various marine settings to reconstruct past sea surface temperatures (SSTs). However, it remains uncertain how well this proxy reconstructs SSTs in marginal seas. In this study, we analyze the environmental factors governing distribution of iGDGTs in surface sediments to assess the applicability of TEX 86 H paleothermometer in the South China Sea (SCS). Individual iGDGT concentrations increase gradually eastwards. Redundancy analysis based on the relative abundance of an individual iGDGT compound and environmental parameters suggests that water depth is the most influential factor to the distribution of iGDGTs, because thaumarchaeota communities are water-depth dependent. Interestingly, the SST difference (Δ T) between TEX 86 H derived temperature and remote-sensing SST is less than 1°C in sediments with water depth>200 m, indicating that TEX 86 H was the robust proxy to trace the paleo-SST in the region if water depth is greater than 200 m.

Where the oil from surface and subsurface plumes deposited during/after Deepwater Horizon oil spill?

NASA Astrophysics Data System (ADS)

Yan, B.

2016-02-01

The Deepwater Horizon (DwH) oil spill released an estimated 4.9 million barrels (about 200 million gallons) of crude oil into the Gulf of Mexico between April 20, 2010 and July 15, 2010. Though Valentine et al. has linked the elevated oil components in some sediments with the subsurface plume, the sites with fallout from the ocean surface plume has not been identified. This piece of information is critical not only for a comprehensive scientific understanding of the ecosystem response and fate of spill-related pollutants, but also for litigation purposes and future spill response and restoration planning. In this study we focus on testing the hypothesis that marine snow from the surface plume were deposited on the sea floor over a broad area. To do so, we use publicly available data generated as part of the ongoing Natural Resource Damage Assessment (NRDA) process to assess the spatial distribution of petroleum hydrocarbons in the water column and deep-ocean sediments of the Gulf of Mexico. Sensitive hydrocarbon markers are used to differentiate hydrocarbons from surface plume, deep subsurface plume, and in-situ burning. Preliminary results suggest the overlapping but different falling sites of these plumes and the sedimentation process was controlled by various biological, chemical, and physical factors.

University of Washington's radioecological studies in the Marshall Islands, 1946-1977.

PubMed

Donaldson, L R; Seymour, A H; Nevissi, A E

1997-07-01

Since 1946, personnel from the School of Fisheries, University of Washington (Applied Fisheries Laboratory, 1943-1958; Laboratory of Radiation Biology, 1958-1967; and Laboratory of Radiation Ecology, since 1967), have studied the effects of nuclear detonations and the ensuing radioactivity on the marine and terrestrial environments throughout the Central Pacific. A collection of reports and publications about these activities plus a collection of several thousand samples from these periods are kept at the School of Fisheries. General findings from the surveys show that (1) fission products were prevalent in organisms of the terrestrial environment whereas activation products were prevalent in marine organisms; (2) the best biological indicators of fallout radionuclides by environments were (a) terrestrial-coconuts, land crabs; (b) reef-algae, invertebrates; and (c) marine-plankton, fish. Studies of plutonium and americium in Bikini Atoll showed that during 1971-1977 the highest concentrations of 241Am, 2.85 Bq g(-1) (77 pCi g(-1)) and 239,240Pu, 4.44 Bq g(-1) (120 pCi g(-1)), in surface sediments were found in the northwest part of the lagoon. The concentrations in the bomb craters were substantially lower than these values. Concentrations of soluble and particulate plutonium and americium in surface and deep water samples showed distributions similar to the sediment samples. That is, the highest concentration of these radionuclides in the water column were at locations with highest sediment concentration. Continuous circulation of water in the lagoon and exchange of water with open ocean resulted in removal of 111 G Bq y(-1) (3 Ci y(-1)) 241Am and 222 G Bq y(-1) (6 Ci y(-1)) 239,240Pu into the North Equatorial Current. A summary of the surveys, findings, and the historical role of the Laboratory in radioecological studies of the Marshall Islands are presented.

Further evaluation of long-chain alkenones as indicators of paleoceanographic conditions

NASA Astrophysics Data System (ADS)

Prahl, Fredrick G.; Muehlhausen, Laurel A.; Zahnle, Debra L.

1988-09-01

Cultures of the marine coccolithophorid, Emiliania huxleyi, were grown in the laboratory at five temperatures (8°, 10°, 15°, 20°, 25°C) and monitored by capillary gas chromatography for their long-chain, unsaturated lipid compositions. The long-chain lipids of this plant comprise a series of C 37, C 38 and C 39 di-, tri- and, in cells grown below 15°C, tetra-unsaturated methyl and ethyl ketones and a methyl and ethyl ester of a di-unsaturated C 36 fatty acid. Systematic changes in the degree of unsaturation and in the overall carbon chain length distribution of the alkenones and in the proportion of fatty acid esters relative to alkenones are noted as a function of growth temperature. We present temperature calibrations for these changes in the lipid composition of laboratory cultures and compare these results with the compositions of this biomarker series measured in a variety of sediments accumulating beneath warm (⩾25°C) and cold (⩽12°C) surface waters in the tropical and temperate North Pacific Ocean, respectively. The comparisons demonstrate 1) this series of biomarkers is deposited in these oceanic sediments with minimal evidence of alteration to its original composition and 2) the strain of E. huxleyi used in this laboratory calibration is representative of the "average" marine phytoplankton supplying this novel series of biomarkers to contemporary sediments in these two environments and a wide variety of other oceanic environments. The long-chain alkenones constitute a major component (8.0 ± 2.9%) of the total organic carbon content of living cells of E. huxleyi. The high cellular abundance of these compounds appears to be relatively constant and independent of the growth temperature of the plant. These biomarkers provide a well-designed and useful geochemical tool for assessing variations not only in surface water temperatures but potentially also in the productivity of an important group of marine phytoplankton in oceans of the recent and distant past.

Risk assessment of trace metal-polluted coastal sediments on Hainan Island: A full-scale set of 474 geographical locations covering the entire island.

PubMed

Li, Feng; Lin, Ze-Feng; Wen, Jia-Sheng; Wei, Yan-Sha; Gan, Hua-Yang; He, Hai-Jun; Lin, Jin-Qin; Xia, Zhen; Chen, Bi-Shuang; Guo, Wen-Jie; Tan, Cha-Sheng; Cai, Hua-Yang

2017-12-15

Hainan Island is the second largest island and one of the most famous tourist destinations in China, but sediment contamination by trace metals in coastal areas is a major issue. However, full-scale risk assessments of trace metal-polluted coastal sediments are lacking. In this study, coastal surface sediments from 474 geographical locations covering almost the entire island were collected to identify risk-related variables. Controlling factors and possible sources of trace metals were identified, and the toxicity effects were carefully evaluated. Our results suggest that trace-metal pollution in coastal sediments, which was mainly caused by Pb, Zn and Cu emissions, has primarily resulted from industrial sewage and shipping activities and has threatened the offshore ecosystem of Hainan Island and warrants extensive consideration. This is the first study that has systematically investigated trace metal-polluted coastal sediments throughout the entirety of Hainan Island and provides solid evidence for sustainable marine management in the region. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Classification and Geomorphic Implications of Thaw Lakes on the Arctic Coastal Plain, Alaska

DTIC Science & Technology

1975-12-01

Plain is underlain by ice-rich marine sediments , the product of several marine transgressions and regressions. Numerous thaw lake basins of...variable morphology and distribution have developed on the perennially frozen sediments (permafrost) of this low-lying plain. Most notable are the large...mechanism of thaw lake formation was recognized whereby sediment laden ice rafts initiated thawing of the permafrost and formation of lake basins

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

NASA Technical Reports Server (NTRS)

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

1974-01-01

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

Testing the Role of Microbial Ecology, Redox-Mediated Deep Water Production and Hypersalinity on TEX86: Lipids and 16s Sequences from Archaea and Bacteria in the Water Column and Sediments of Orca Basin

NASA Astrophysics Data System (ADS)

Warren, C.; Romero, I.; Ellis, G.; Goddard, E.; Krishnan, S.; Nigro, L. M.; Super, J. R.; Zhang, Y.; Zhuang, G.; Hollander, D. J.; Pagani, M.

2014-12-01

Mesophilic marine archaea and bacteria are known to substantially contribute to the oceanic microbial biomass and play critical roles in global carbon, nitrogen and nutrient cycles. The Orca Basin, a 2400 meter deep bathymetric depression on the continental slope of the north-central Gulf of Mexico, is an ideal environment to examine how redox-dependent biochemical processes control the input and cycling of bacterial and archaea-derived lipid compounds from formation in near-surface water, through secondary recycling processes operating at the redox-transition in the water column, to sedimentary diagenetic processes operating in oxic to anoxic zones within the basin. The lowermost 180 meters of the Orca Basin is characterized by an anoxic, hypersaline brine that is separated from the overlying oxic seawater by a well-defined redox sequence associated with a systematic increasing in salinity from 35 - 250‰. While surface water conditions are viewed as normal marine with a seasonally productive water column, the sub-oxic to anoxic transition zones within the deep-water column and the sediment spans over 200 m allowing the unique opportunity for discrete sampling of resident organisms and lipids. Here we present 16s rRNA sequence data of Bacteria and Archaea collected parallel to GDGT lipid profiles and in situ environmental measurements from the sediment and overlying water column in the intermediate zone of the basin, where movements of chemical transition zones are preserved. We evaluated GDGTs and corresponding taxa across the surface water, chlorophyll maximum, thermocline, and the deep redox boundary, including oxygenation, denitrification, manganese, iron and sulfate reduction zones, to determine if GDGTs are being produced under these conditions and how surface-derived GDGT lipids and the TEX86 signal may be altered. The results have implications for the application of the TEX86 paleotemperature proxy.

Planktonic foraminifera-derived environmental DNA extracted from abyssal sediments preserves patterns of plankton macroecology

NASA Astrophysics Data System (ADS)

Morard, Raphaël; Lejzerowicz, Franck; Darling, Kate F.; Lecroq-Bennet, Béatrice; Winther Pedersen, Mikkel; Orlando, Ludovic; Pawlowski, Jan; Mulitza, Stefan; de Vargas, Colomban; Kucera, Michal

2017-06-01

Deep-sea sediments constitute a unique archive of ocean change, fueled by a permanent rain of mineral and organic remains from the surface ocean. Until now, paleo-ecological analyses of this archive have been mostly based on information from taxa leaving fossils. In theory, environmental DNA (eDNA) in the sediment has the potential to provide information on non-fossilized taxa, allowing more comprehensive interpretations of the fossil record. Yet, the process controlling the transport and deposition of eDNA onto the sediment and the extent to which it preserves the features of past oceanic biota remains unknown. Planktonic foraminifera are the ideal taxa to allow an assessment of the eDNA signal modification during deposition because their fossils are well preserved in the sediment and their morphological taxonomy is documented by DNA barcodes. Specifically, we re-analyze foraminiferal-specific metabarcodes from 31 deep-sea sediment samples, which were shown to contain a small fraction of sequences from planktonic foraminifera. We confirm that the largest portion of the metabarcode originates from benthic bottom-dwelling foraminifera, representing the in situ community, but a small portion (< 10 %) of the metabarcodes can be unambiguously assigned to planktonic taxa. These organisms live exclusively in the surface ocean and the recovered barcodes thus represent an allochthonous component deposited with the rain of organic remains from the surface ocean. We take advantage of the planktonic foraminifera portion of the metabarcodes to establish to what extent the structure of the surface ocean biota is preserved in sedimentary eDNA. We show that planktonic foraminifera DNA is preserved in a range of marine sediment types, the composition of the recovered eDNA metabarcode is replicable and that both the similarity structure and the diversity pattern are preserved. Our results suggest that sedimentary eDNA could preserve the ecological structure of the entire pelagic community, including non-fossilized taxa, thus opening new avenues for paleoceanographic and paleoecological studies.

Denudation of the continental shelf between Britain and France at the glacial–interglacial timescale

PubMed Central

Mellett, Claire L.; Hodgson, David M.; Plater, Andrew J.; Mauz, Barbara; Selby, Ian; Lang, Andreas

2013-01-01

The erosional morphology preserved at the sea bed in the eastern English Channel dominantly records denudation of the continental shelf by fluvial processes over multiple glacial–interglacial sea-level cycles rather than by catastrophic flooding through the Straits of Dover during the mid-Quaternary. Here, through the integration of multibeam bathymetry and shallow sub-bottom 2D seismic reflection profiles calibrated with vibrocore records, the first stratigraphic model of erosion and deposition on the eastern English Channel continental shelf is presented. Published Optical Stimulated Luminescence (OSL) and 14C ages were used to chronometrically constrain the stratigraphy and allow correlation of the continental shelf record with major climatic/sea-level periods. Five major erosion surfaces overlain by discrete sediment packages have been identified. The continental shelf in the eastern English Channel preserves a record of processes operating from Marine Isotope Stage (MIS) 6 to MIS 1. Planar and channelised erosion surfaces were formed by fluvial incision during lowstands or relative sea-level fall. The depth and lateral extent of incision was partly conditioned by underlying geology (rock type and tectonic structure), climatic conditions and changes in water and sediment discharge coupled to ice sheet dynamics and the drainage configuration of major rivers in Northwest Europe. Evidence for major erosion during or prior to MIS 6 is preserved. Fluvial sediments of MIS 2 age were identified within the Northern Palaeovalley, providing insights into the scale of erosion by normal fluvial regimes. Seismic and sedimentary facies indicate that deposition predominantly occurred during transgression when accommodation was created in palaeovalleys to allow discrete sediment bodies to form. Sediment reworking over multiple sea-level cycles (Saalian–Eemian–early Weichselian) by fluvial, coastal and marine processes created a multi-lateral, multi-storey succession of palaeovalley-fills that are preserved as a strath terrace. The data presented here reveal a composite erosional and depositional record that has undergone a high degree of reworking over multiple sea-level cycles leading to the preferential preservation of sediments associated with the most recent glacial–interglacial period. PMID:24748702

Denudation of the continental shelf between Britain and France at the glacial-interglacial timescale.

PubMed

Mellett, Claire L; Hodgson, David M; Plater, Andrew J; Mauz, Barbara; Selby, Ian; Lang, Andreas

2013-12-01

The erosional morphology preserved at the sea bed in the eastern English Channel dominantly records denudation of the continental shelf by fluvial processes over multiple glacial-interglacial sea-level cycles rather than by catastrophic flooding through the Straits of Dover during the mid-Quaternary. Here, through the integration of multibeam bathymetry and shallow sub-bottom 2D seismic reflection profiles calibrated with vibrocore records, the first stratigraphic model of erosion and deposition on the eastern English Channel continental shelf is presented. Published Optical Stimulated Luminescence (OSL) and 14 C ages were used to chronometrically constrain the stratigraphy and allow correlation of the continental shelf record with major climatic/sea-level periods. Five major erosion surfaces overlain by discrete sediment packages have been identified. The continental shelf in the eastern English Channel preserves a record of processes operating from Marine Isotope Stage (MIS) 6 to MIS 1. Planar and channelised erosion surfaces were formed by fluvial incision during lowstands or relative sea-level fall. The depth and lateral extent of incision was partly conditioned by underlying geology (rock type and tectonic structure), climatic conditions and changes in water and sediment discharge coupled to ice sheet dynamics and the drainage configuration of major rivers in Northwest Europe. Evidence for major erosion during or prior to MIS 6 is preserved. Fluvial sediments of MIS 2 age were identified within the Northern Palaeovalley, providing insights into the scale of erosion by normal fluvial regimes. Seismic and sedimentary facies indicate that deposition predominantly occurred during transgression when accommodation was created in palaeovalleys to allow discrete sediment bodies to form. Sediment reworking over multiple sea-level cycles (Saalian-Eemian-early Weichselian) by fluvial, coastal and marine processes created a multi-lateral, multi-storey succession of palaeovalley-fills that are preserved as a strath terrace. The data presented here reveal a composite erosional and depositional record that has undergone a high degree of reworking over multiple sea-level cycles leading to the preferential preservation of sediments associated with the most recent glacial-interglacial period.

Dispersal of thermophilic Desulfotomaculum endospores into Baltic Sea sediments over thousands of years.

PubMed

de Rezende, Júlia Rosa; Kjeldsen, Kasper Urup; Hubert, Casey R J; Finster, Kai; Loy, Alexander; Jørgensen, Bo Barker

2013-01-01

Patterns of microbial biogeography result from a combination of dispersal, speciation and extinction, yet individual contributions exerted by each of these mechanisms are difficult to isolate and distinguish. The influx of endospores of thermophilic microorganisms to cold marine sediments offers a natural model for investigating passive dispersal in the ocean. We investigated the activity, diversity and abundance of thermophilic endospore-forming sulfate-reducing bacteria (SRB) in Aarhus Bay by incubating pasteurized sediment between 28 and 85 °C, and by subsequent molecular diversity analyses of 16S rRNA and of the dissimilatory (bi)sulfite reductase (dsrAB) genes within the endospore-forming SRB genus Desulfotomaculum. The thermophilic Desulfotomaculum community in Aarhus Bay sediments consisted of at least 23 species-level 16S rRNA sequence phylotypes. In two cases, pairs of identical 16S rRNA and dsrAB sequences in Arctic surface sediment 3000 km away showed that the same phylotypes are present in both locations. Radiotracer-enhanced most probable number analysis revealed that the abundance of endospores of thermophilic SRB in Aarhus Bay sediment was ca. 10(4) per cm(3) at the surface and decreased exponentially to 10(0) per cm(3) at 6.5 m depth, corresponding to 4500 years of sediment age. Thus, a half-life of ca. 300 years was estimated for the thermophilic SRB endospores deposited in Aarhus Bay sediments. These endospores were similarly detected in the overlying water column, indicative of passive dispersal in water masses preceding sedimentation. The sources of these thermophiles remain enigmatic, but at least one source may be common to both Aarhus Bay and Arctic sediments.

Dispersal of thermophilic Desulfotomaculum endospores into Baltic Sea sediments over thousands of years

PubMed Central

de Rezende, Júlia Rosa; Kjeldsen, Kasper Urup; Hubert, Casey R J; Finster, Kai; Loy, Alexander; Jørgensen, Bo Barker

2013-01-01

Patterns of microbial biogeography result from a combination of dispersal, speciation and extinction, yet individual contributions exerted by each of these mechanisms are difficult to isolate and distinguish. The influx of endospores of thermophilic microorganisms to cold marine sediments offers a natural model for investigating passive dispersal in the ocean. We investigated the activity, diversity and abundance of thermophilic endospore-forming sulfate-reducing bacteria (SRB) in Aarhus Bay by incubating pasteurized sediment between 28 and 85 °C, and by subsequent molecular diversity analyses of 16S rRNA and of the dissimilatory (bi)sulfite reductase (dsrAB) genes within the endospore-forming SRB genus Desulfotomaculum. The thermophilic Desulfotomaculum community in Aarhus Bay sediments consisted of at least 23 species-level 16S rRNA sequence phylotypes. In two cases, pairs of identical 16S rRNA and dsrAB sequences in Arctic surface sediment 3000 km away showed that the same phylotypes are present in both locations. Radiotracer-enhanced most probable number analysis revealed that the abundance of endospores of thermophilic SRB in Aarhus Bay sediment was ca. 104 per cm3 at the surface and decreased exponentially to 100 per cm3 at 6.5 m depth, corresponding to 4500 years of sediment age. Thus, a half-life of ca. 300 years was estimated for the thermophilic SRB endospores deposited in Aarhus Bay sediments. These endospores were similarly detected in the overlying water column, indicative of passive dispersal in water masses preceding sedimentation. The sources of these thermophiles remain enigmatic, but at least one source may be common to both Aarhus Bay and Arctic sediments. PMID:22832348

Concentrations and sources of polycyclic aromatic hydrocarbons in surface coastal sediments of the northern Gulf of Mexico

PubMed Central

2014-01-01

Background Coastal sediments in the northern Gulf of Mexico have a high potential of being contaminated by petroleum hydrocarbons, such as polycyclic aromatic hydrocarbons (PAHs), due to extensive petroleum exploration and transportation activities. In this study we evaluated the spatial distribution and contamination sources of PAHs, as well as the bioavailable fraction in the bulk PAH pool, in surface marsh and shelf sediments (top 5 cm) of the northern Gulf of Mexico. Results PAH concentrations in this region ranged from 100 to 856 ng g−1, with the highest concentrations in Mississippi River mouth sediments followed by marsh sediments and then the lowest concentrations in shelf sediments. The PAH concentrations correlated positively with atomic C/N ratios of sedimentary organic matter (OM), suggesting that terrestrial OM preferentially sorbs PAHs relative to marine OM. PAHs with 2 rings were more abundant than those with 5–6 rings in continental shelf sediments, while the opposite was found in marsh sediments. This distribution pattern suggests different contamination sources between shelf and marsh sediments. Based on diagnostic ratios of PAH isomers and principal component analysis, shelf sediment PAHs were petrogenic and those from marsh sediments were pyrogenic. The proportions of bioavailable PAHs in total PAHs were low, ranging from 0.02% to 0.06%, with higher fractions found in marsh than shelf sediments. Conclusion PAH distribution and composition differences between marsh and shelf sediments were influenced by grain size, contamination sources, and the types of organic matter associated with PAHs. Concentrations of PAHs in the study area were below effects low-range, suggesting a low risk to organisms and limited transfer of PAHs into food web. From the source analysis, PAHs in shelf sediments mainly originated from direct petroleum contamination, while those in marsh sediments were from combustion of fossil fuels. PMID:24641695

Sediment data collected in 2010 from Cat Island, Mississippi

USGS Publications Warehouse

Buster, Noreen A.; Kelso, Kyle W.; Miselis, Jennifer L.; Kindinger, Jack G.

2014-01-01

Scientists from the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, in collaboration with the U.S. Army Corps of Engineers, conducted geophysical and sedimentological surveys in 2010 around Cat Island, Mississippi, which is the westernmost island in the Mississippi-Alabama barrier island chain. The objective of the study was to understand the geologic evolution of Cat Island relative to other barrier islands in the northern Gulf of Mexico by identifying relationships between the geologic history, present day morphology, and sediment distribution. This data series serves as an archive of terrestrial and marine sediment vibracores collected August 4-6 and October 20-22, 2010, respectively. Geographic information system data products include marine and terrestrial core locations and 2007 shoreline data. Additional files include marine and terrestrial core description logs, core photos, results of sediment grain-size analyses, optically stimulated luminescence dating and carbon-14 dating locations and results, Field Activity Collection System logs, and formal Federal Geographic Data Committee metadata.

Immediate propagation of deglacial environmental change to turbidite systems along the Chilean continental slope

NASA Astrophysics Data System (ADS)

Bernhardt, Anne; Schwanghart, Wolfgang; Hebbeln, Dierk; Stuut, Jan-Berend; Strecker, Manfred

2017-04-01

Understanding how Earth-surface processes respond to past climatic perturbations is crucial for making informed predictions about future impacts of climate change on sediment fluxes. Sedimentary records provide the archives for inferring these processes but their interpretation is compromised by our incomplete understanding of how sediment-routing systems respond to millennial-scale climate cycles. We analyzed seven sediment cores recovered from turbidite depositional sites along the continental slope of the Chile convergent margin. These depositional systems represent the ultimate sedimentary archives before sediment gets recycled during subduction processes and provide relatively continuous and well-dated records. The study sites span a pronounced arid-to-humid gradient with variable topographic gradients and related connectivity of terrestrial and marine landscapes on the continental slope. This setting allowed us to study event-related depositional processes from the Last Glacial Maximum to present in different climatic and geomorphic settings. The turbidite record was quantified in terms of turbidite thickness and frequency. The three studied sites show a steep decline of turbidite deposition during deglaciation. High rates of sea-level rise significantly lag the decline in turbidite deposition by 3-6.5 kyrs. However, comparison to paleoclimate proxies shows that this spatio-temporal sedimentary pattern mirrors the deglacial humidity decrease and concomitant warming with little to no lag times. Our results suggest that the deglacial humidity decrease resulted in a decrease of fluvial sediment supply, which propagated rapidly through the highly connected systems into the marine sink in north-central Chile. In contrast, in south-central Chilean systems, connectivity between the Andean erosional zone and the fluvial transfer zone probably decreased abruptly by the deglaciation of piedmont lakes, resulting in a significant and rapid decrease of sediment supply to the ocean. Additionally, reduced moisture supply may have also contributed to the rapid decline of turbidite deposition. These different causes result in similar depositional patterns in the marine sinks. We conclude that turbiditic strata can act as reliable recorders of climate change across a wide range of climatic zones and geomorphic conditions. However, the underlying causes for similar signal manifestations in the sinks may differ, ranging from maintained high system connectivity to abrupt connectivity loss.

Ocean acidification and the δ15N record of Paleozoic epeiric seas

NASA Astrophysics Data System (ADS)

Tuite, M. L., Jr.; Williford, K. H.

2017-12-01

In addition to its role as a primary driver of global climate, atmospheric CO2 influences the pH of seawater which is an important factor in mediating biogeochemical cycles. Variations in the pH of seawater on geological timescales have been correlated with broad impacts on marine ecosystems and biogeochemical processes including evolutionary turnover and mass extinction. Atmospheric CO2 declined dramatically during the mid-Paleozoic, coincident with the emergence of terrestrial forests and concomitant development of a substantial soil carbon reservoir and increased silicate weathering. Global greenhouse conditions that prevailed at the Late Devonian Frasnian/Famennian boundary gave way to temperate latitude glaciation at the end of the Famennian. In a recent review of icehouse-greenhouse variations in marine nitrogen biogeochemistry through the Phanerozoic (Algeo et al. 2014), the authors observed a strong correlation between sediment δ15N and first order climate cycles with a trend toward lower values during greenhouse periods and higher values during icehouse periods. Based upon modeling results, the shift in sediment δ15N was ascribed to a change in the locus of denitrification from sediments in warm climates to the water column during cooler periods driven primarily by eustatic sea level change as glacial ice mass waxed and waned. Sediment δ15N is a useful proxy for interpreting N biogeochemistry in marine systems because it provides an integrated record of the microbially-mediated redox reactions that led to that δ15N value. We propose that the elevated CO2 that drove the greenhouse climate in the early Famennian also resulted in the acidification of seawater that precluded nitrification, yielding an ammonium-dominated surface ocean and low sediment δ15N. As O2 climbed and seawater pH responded to diminished CO2, we propose that nitrification rates increased resulting in a nitrate-dominated system and sediment δ15N values that approach modern values. In support of our argument, we present stable isotope, redox, and compositional data from a core that spans the transition from the high CO2 greenhouse climate near the F/F boundary to the lower CO2 climate in the latest Devonian.

Fe-C-S systematics in Bengal Fan sediments

NASA Astrophysics Data System (ADS)

Volvoikar, S. P.; Mazumdar, A.; Goswami, H.; Pujari, S.; Peketi, A.

2017-12-01

Global biogeochemical cycles of iron, carbon and sulfur (Fe-C-S) are interrelated. Sulfate reduction in marine sediments is the major factor controlling the cycling and burial of carbon, sulfur and iron. Organoclastic sulfate reduction and anaerobic oxidation of methane (AOM) are the two main processes responsible for sulfate reduction in marine sediments. The amount and reactivity of organic matter, iron minerals and concentrations of dissolved sulfide in pore water control the burial of iron sulfide and organic bound sulfur in marine sediments. Here we investigate the sulfidization process in a sediment core from the western part of upper Bay of Bengal fan characterized by efficient burial of organic matter with siliclastic load. A 30 m long sediment core (MD 161/29, Lat. 170 18.04' N, Long. 870 22.56' E, water depth: 2434m) was collected onboard Marion Dufresne (May, 2007) and studied for Fe-S speciation and organic matter characterization. Buffered dithionite extractable iron (FeD) varies from 0.71 to 1.43 wt % (Avg. 0.79 wt %). FeD represents Fe oxides and oxyhydroxides mainly, ferrihydrite, lepidocrocite, goethite and hematite. Acid volatile sulfur (AVS) varies from 0.0015 to 0.63 wt % (avg: 0.058 wt %), while chromium reducible sulfur (CRS) varies from 0.00047 to 0.29 wt % (avg. 0.054 wt %). Based on the vertical distribution patterns of FeD, AVS and CRS, the core is divided into three zones, the lower (3000 to 1833 cm), middle (1833 to 398 cm) and upper (398 cm to surface) zones. FeD shows higher concentration in the lower zone. FeTR (FeOx + FeD + FeCRS + FeAVS) also exhibit higher concentration in this zone, suggesting higher availability of reactive iron for iron sulfide precipitation. AVS, elemental sulfur, spikes of CRS and gradual enrichment of δ34SAVS and δ34SCRS with sharp peaks in-between is noted in the lower zone. The gradual enrichment of δ34SAVS and δ34SCRS is the outcome of late diagenetic pyritization with higher availability of sulfide (HS- and H2S) from AOM.

Sediment impacts on marine sponges.

PubMed

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

2015-05-15

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

Microbial dehalogenation of organohalides in marine and estuarine environments.

PubMed

Zanaroli, Giulio; Negroni, Andrea; Häggblom, Max M; Fava, Fabio

2015-06-01

Marine sediments are the ultimate sink and a major entry way into the food chain for many highly halogenated and strongly hydrophobic organic pollutants, such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), polybrominated diphenylethers (PBDEs) and 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT). Microbial reductive dehalogenation in anaerobic sediments can transform these contaminants into less toxic and more easily biodegradable products. Although little is still known about the diversity of respiratory dehalogenating bacteria and their catabolic genes in marine habitats, the occurrence of dehalogenation under actual site conditions has been reported. This suggests that the activity of dehalogenating microbes may contribute, if properly stimulated, to the in situ bioremediation of marine and estuarine contaminated sediments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sedimentary architecture and depositional environment of Kudat Formation, Sabah, Malaysia

NASA Astrophysics Data System (ADS)

Ghaheri, Samira; Suhaili, Mohd; Sapari, Nasiman; Momeni, Mohammadsadegh

2017-12-01

Kudat Formation originated from deep marine environment. Three lithofacies association of deep marine turbidity channel was discovered in three Members of the Kudat Formation in Kudat Peninsula, Sabah, Malaysia. Turbidite and deep marine architecture elements was described based on detailed sedimentological studies. Four architecture elements were identified based on each facies association and their lithology properties and character: inner external levee that was formed by turbidity flows spill out from their confinement of channel belt; Lobes sheet that was formed during downslope debris flows associated with levee; Channel fill which sediments deposited from high to low density currents with different value of sediment concentration; and overbank terrace which was formed by rapid suspension sedimentation. The depositional environment of Kudat Formation is shelf to deep marine fan.

Cycling of Redox-Sensitive Trace Elements in the Lower Mississippi River Delta as a Function of River Stage and Sediment Heterogeneity

NASA Astrophysics Data System (ADS)

Telfeyan, K.; Breaux, A.; Kim, J.; Johannesson, K. H.; Kolker, A.; Cable, J. E.

2015-12-01

Telfeyan, K.1, Johannesson, K.H.1, Breaux, A.M.2,1, Kim, J.3, Kolker, A.S.2,1, Cable, J.E.31 Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA, USA 2 Louisiana Universities Marine Consortium, Cocoderie, LA, USA 3 Department of Marine Sciences, University of North Carolina, Chapel Hill, NC, USA The Mississippi River drains 40% of the continental United States and discharges 0.1 Pg sediment and an average of 18,400 m3 s-1 water annually to the Gulf of Mexico1. The flow of groundwater through the Mississippi River Delta (MRD) to the Gulf, however, has been largely understudied and is typically overlooked in MRD biogeochemical studies. Previous work demonstrated that sand-rich paleochannels that maintain a hydrologic connection to the Mississippi River could transport riverine water to the MRD2. We present data from biogeochemical surveys at 2 sites in the lower MRD to explore the effects of river-derived submarine groundwater discharge on the biogeochemistry of MRD wetlands. Lac des Allemands is a fresh water lake and Myrtle Grove is a brackish canal with variable salinities. Both are surrounded by extensive wetlands. Over the course of a year, surface water, shallow pore water, and deeper groundwaters were sampled to understand the cycling of redox-sensitive trace elements (Fe, Mn, V, As) and the potential supply from groundwater to surface water bodies. Major ion chemistry suggests that both Lac des Allemands and Myrtle Grove Canal receive river-derived terrestrial water at their heads, the flux of which varies as a function of river stage. However, the lateral flow through adjacent wetlands is altered as a function of sediment heterogeneity. Evidence for sulfate reduction exists in the near-surface sediment and at depth where a continuous vertical organic matter layer exists. In sand-rich layers, iron reduction buffers redox conditions, and V varies inversely with dissolved Fe. Concentrations of V and As are much greater in near-surface pore waters than in deeper groundwaters and in surface waters, suggesting that the subterranean estuary serves as a sink of these redox-sensitive trace elements. [1] Bianchi and Allison (2009) PNAS 1068085-8092. [2] Kolker et al. (2013) Journal of Hydrology 498 319-334.

Steps Towards Understanding Large-scale Deformation of Gas Hydrate-bearing Sediments

NASA Astrophysics Data System (ADS)

Gupta, S.; Deusner, C.; Haeckel, M.; Kossel, E.

2016-12-01

Marine sediments bearing gas hydrates are typically characterized by heterogeneity in the gas hydrate distribution and anisotropy in the sediment-gas hydrate fabric properties. Gas hydrates also contribute to the strength and stiffness of the marine sediment, and any disturbance in the thermodynamic stability of the gas hydrates is likely to affect the geomechanical stability of the sediment. Understanding mechanisms and triggers of large-strain deformation and failure of marine gas hydrate-bearing sediments is an area of extensive research, particularly in the context of marine slope-stability and industrial gas production. The ultimate objective is to predict severe deformation events such as regional-scale slope failure or excessive sand production by using numerical simulation tools. The development of such tools essentially requires a careful analysis of thermo-hydro-chemo-mechanical behavior of gas hydrate-bearing sediments at lab-scale, and its stepwise integration into reservoir-scale simulators through definition of effective variables, use of suitable constitutive relations, and application of scaling laws. One of the focus areas of our research is to understand the bulk coupled behavior of marine gas hydrate systems with contributions from micro-scale characteristics, transport-reaction dynamics, and structural heterogeneity through experimental flow-through studies using high-pressure triaxial test systems and advanced tomographical tools (CT, ERT, MRI). We combine these studies to develop mathematical model and numerical simulation tools which could be used to predict the coupled hydro-geomechanical behavior of marine gas hydrate reservoirs in a large-strain framework. Here we will present some of our recent results from closely co-ordinated experimental and numerical simulation studies with an objective to capture the large-deformation behavior relevant to different gas production scenarios. We will also report on a variety of mechanically relevant test scenarios focusing on effects of dynamic changes in gas hydrate saturation, highly uneven gas hydrate distributions, focused fluid migration and gas hydrate production through depressurization and CO2 injection.

PEaCH4 v.2.0: A modelling platform to predict early diagenetic processes in marine sediments with a focus on biogenic methane - Case study: Offshore Namibia

NASA Astrophysics Data System (ADS)

Arning, Esther T.; Häußler, Steffen; van Berk, Wolfgang; Schulz, Hans-Martin

2016-07-01

The modelling of early diagenetic processes in marine sediments is of interest in marine science, and in the oil and gas industry, here, especially with respect to methane occurrence and gas hydrate formation as resources. Early diagenesis in marine sediments evolves from a complex web of intertwining (bio)geochemical reactions. It comprises microbially catalysed reactions and inorganic mineral-water-gas interactions. A model that will describe and consider all of these reactions has to be complex. However, it should be user-friendly, as well as to be applicable for a broad community and not only for experts in the field of marine chemistry. The presented modelling platform PeaCH4 v.2.0 combines both aspects, and is Microsoft Excel©-based. The modelling tool is PHREEQC (version 2), a computer programme for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations. The conceptual PEaCH4 model is based on the conversion of sediment-bound degradable organic matter. PEaCH4 v.2.0 was developed to quantify and predict early diagenetic processes in marine sediments with the focus on biogenic methane formation and its phase behaviour, and allows carbon mass balancing. In regard to the irreversible degradation of organic matter, it comprises a "reaction model" and a "kinetic model" to predict methane formation. Both approaches differ in their calculations and outputs as the "kinetic model" considers the modelling time to integrate temperature dependent biogenic methane formation in its calculations, whereas the "reaction model" simply relies on default organic matter degradation. With regard to the inorganic mineral-water-gas interactions, which are triggered by irreversible degradation of organic matter, PEaCH4 v.2.0 is based on chemical equilibrium thermodynamics, appropriate mass-action laws, and their temperature dependent equilibrium constants. The programme is exemplarily presented with the example of upwelling sediments off Namibia, ODP Leg 175, Site 1082. The application demonstrates that the modelling platform PEaCH4 v.2.0 provides a user-friendly, but complex scientific tool that delivers retraceable information about early diagenetic processes and products in marine sediments.

A giant sediment trap in the Florida keys

USGS Publications Warehouse

Shinn, E.A.; Reich, C.D.; Locker, S.D.; Hine, A.C.

1996-01-01

Aerial photography, high-resolution seismic profiling, coring and jet probing have revealed a large sediment-filled sinkhole in the Key Largo National Marine Sanctuary off Key Largo, Florida. The 600-m-diameter feature straddles coral reef and carbonate-sand facies and contains >55 m of marine lime sand and aragonite mud. Bulk 14C age determinations of mud from a 30- m sediment core indicate infilling rates exceeding 20 m/ka between 3 and 5.6 ka. The total thickness and nature of the sediment near the base of the sinkhole are not known.

Determination of alcohol sulfates and alcohol ethoxysulfates in marine and river sediments using liquid chromatography-tandem mass spectrometry.

PubMed

Fernández-Ramos, C; Ballesteros, O; Blanc, R; Zafra-Gómez, A; Camino-Sánchez, F J; Navalón, A; Vílchez, J L

2013-10-15

A novel and successful method has been developed for the identification and quantification of alcohol sulfates (AS) homologues and alcohol ethoxysulfates (AES) ethoxymers in marine and river sediment samples. The method involves the extraction of 5.00 g of dry sample with methanol using pressurized liquid extraction (PLE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). 2-Octylbenzene sulfonic acid sodium salt (2ØC8-LAS) was used as internal standard. The analytical methods were applied to marine sediments collected from the coast of Almeria (South-east Spain) and river sediments collected from the Monachil river (Granada, South-east Spain). For AS homologues, the found limits of detection were 0.04-0.08 μg g(-1) for marine and river sediments. For AES ethoxymers, the found limits of detection were 0.03-0.09 μg g(-1) and 0.06-0.22 μg g(-1) for marine and river sediments, respectively. The highest concentrations of AS and AES were found in river sediment samples. Significant differences were also observed between the behavior of short-chain compounds (C12) and long-chain compounds (C14 to C18). The influence of the physic-chemical properties of water on the occurrence of these compounds was also evaluated, and differences between long- and short-chain compounds were also observed. Additionally, principal components analyses were carried out in order to study the relationship between variables and to evaluate the sources of data variability and behavior patterns. Finally, important conclusions were drawn regarding the environmental behavior of AS and AES. Copyright © 2013 Elsevier B.V. All rights reserved.

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

PubMed

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.

Late Quaternary stratigraphy of the eastern Gulf of Maine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bacchus, T.S.; Belknap, D.F.

1993-03-01

Five distinct seismic facies describe the glacial, glacial-marine and postglacial sediments in the eastern Gulf of Maine. Regional cross-sections clearly document differences in the glacial-marine and postglacial stratigraphy between basins south of Truxton Swell, and Jordan basin to its north. Till occurs throughout the region as a thin veneer within basins, but thickens significantly over the ridges and swells separating basins. The ubiquitous presence of till suggests grounded ice occupied this area some time in the recent past. Ice-proximal glacial-marine (PGM) facies sediments of varying thickness mantle the entire area, occurring as a draped unit over pre-existing topography. Transitional glacial-marinemore » (TGM) facies also occur as a draped unit, but they show onlap onto basin margins. Sediments of the TGM facies are restricted to areas south of Truxton Swell. Ice-distal glacial-marine (DGM) facies sediments also mantle the entire area, but they occur primarily as a ponded, infilling unit. The nature and distribution of these glacial-marine facies within the eastern Gulf of Maine documents changes in the environment of deposition during deglaciation. In the authors model PGM facies sediments are considered to represent settling through the water column of coarse material from the base of an ice shelf. TGM facies sediments indicate retreat of this ice margin coupled with calving of large icebergs with significant amounts of coarse debris, DGM facies sediments indicate further retreat of the ice margin and a lessening of the influence of icebergs. Stepwise ice-margin retreat from south to north through a series of grounding lines and associated pinning points is evident by these time transgressive sedimentary facies that can be correlated across the region.« less

Fingerprinting of bed sediment in the Tay Estuary, Scotland: an environmental magnetism approach

NASA Astrophysics Data System (ADS)

Jenkins, Pierre A.; Duck, Rob W.; Rowan, John S.; Walden, John

Sediment fingerprinting is commonly used for sediment provenance studies in lakes, rivers and reservoirs and on hillslopes and floodplains. This investigation explores the mixing of terrestrial and marine-derived sediment in the Tay Estuary, Scotland, using mineral magnetic attributes for fingerprinting. Samples representative of the estuary sediments and of four sources (end-members) were subjected to a suite of magnetic susceptibility and remanence measurements. Sediment samples from the beds of the Rivers Tay and Earn represented fluvial inputs while samples from the Angus and Fife coasts represented marine input. Multivariate discriminant and factor analysis showed that the sources could be separated on the basis of six magnetic parameters in a simple multivariate unmixing model to identify source contributions to estuarine bed sediments. Multi-domain magnetite signatures, characteristic of unweathered bedrock, dominate the magnetic measurements. Overall contributions of 3% from the River Earn, 17% from the River Tay, 29% from the Angus coast and 51% from the Fife coast source end-members, demonstrated the present-day regime of marine sediment derivation in the Tay Estuary. However, this conceals considerable spatial variability both along-estuary and in terms of sub-environments, with small-scale variations in sediment provenance reflecting local morphology, particularly areas of channel convergence.

Evolution of the Lian River coastal basin in response to Quaternary marine transgressions in Southeast China

NASA Astrophysics Data System (ADS)

Tang, Yongjie; Zheng, Zhuo; Chen, Cong; Wang, Mengyuan; Chen, Bishan

2018-04-01

The coastal basin deposit in the Lian River plain is among the thickest Quaternary sequences along the southeastern coast of China. The clastic sediment accumulated in a variety of environmental settings including fluvial, channel, estuary/coastal and marine conditions. Detailed investigation of lithofacies, grain-size distributions, magnetic susceptibility, microfossils and chronology of marine core CN01, compared with regional cores, and combined with offshore seismic reflection profiles, has allowed us to correlate the spatial stratigraphy in the inner and outer plain and the seismic units. Grain size distribution analysis of core CN-01 through compositional data analysis and multivariate statistics were applied to clastic sedimentary facies and sedimentary cycles. Results show that these methods are able to derive a robust proxy information for the depositional environment of the Lian River plain. We have also been able to reconstruct deltaic evolution in response to marine transgressions. On the basis of dating results and chronostratigraphy, the estimated age of the onset of deposition in the Lian River coastal plain was more than 260 kyr BP. Three transgressive sedimentary cycles revealed in many regional cores support this age model. Detailed lithological and microfossil studies confirm that three marine (M3, M2 and M1) and three terrestrial (T3, T2 and T1) units can be distinguished. Spatial correlation between the inner plain, outer plain (typical cores characterized by marine transgression cycles) and offshore seismic reflectors reveals coherent sedimentary sequences. Two major boundaries (unconformity and erosion surfaces) can be recognized in the seismic profiles, and these correspond to weathered reddish and/or variegated clay in the study core, suggesting that Quaternary sediment changes on the Lian River plain were largely controlled by sea-level variations and coastline shift during glacial/interglacial cycles.

Oxidative dissolution of pyrite surfaces by hexavalent chromium: Surface site saturation and surface renewal

NASA Astrophysics Data System (ADS)

Graham, Andrew M.; Bouwer, Edward J.

2012-04-01

In-situ reduction of toxic Cr(VI) to nontoxic Cr(III) represents an important natural attenuation process for Cr(VI)-impacted environments. This study investigates the stoichiometry and kinetics of Cr(VI) reduction by pyrite, a reduced iron-sulfur mineral ubiquitous in recent estuarine and marine sediments. Pyrite suspensions at surface loadings of 0.28-2.10 m2/L (typical of estuarine or marine sediments) were capable of completely reducing 7-120 μM Cr(VI) on the timescale of minutes to days, with the time to reaction completion decreasing with increasing pyrite loading, decreasing initial Cr(VI) concentration, and decreasing suspension pH. Analysis of metal species (Cr and Fe) and sulfur species in solution and at the mineral surface indicated that Cr(VI) oxidatively dissolved the pyrite surface, releasing ferrous iron and sulfate into solution as the reaction progressed. Surface disulfide groups were postulated as the Cr(VI)-reactive surface entity. Net production or consumption of aqueous Fe(II) was shown to depend upon the relative rates of proton-promoted Fe(II) release, Fe(II) release due to oxidative dissolution of pyrite in the presence of Cr(VI), and Fe(II) consumption due to homogeneous reaction with Cr(VI). Kinetics of Cr(VI) reduction by pyrite displayed a biphasic pattern, and the time to reaction completion increased dramatically with increasing initial Cr(VI) concentration. Rapid Cr(VI) removal occurred early in the reaction progress, attributable to Cr(VI) loss under an adsorption-limited regime. Slow, approximately zero-order, Cr(VI) removal occurred over the bulk of the time courses, and corresponded to Cr(VI) removal under surface site saturation conditions. Stoichiometric Cr(VI) reduction was able to proceed under surface site limited conditions owing to regeneration of reactive surface sites following desorption/dissolution of oxidized surface products, as demonstrated in repeat Cr(VI)-spiking experiments. The role of surface passivation was evaluated by comparing rates of Cr(VI) reduction in the presence and absence of the Cr(III)-complexing agent citrate. While citrate addition significantly enhanced Cr(III) solubility, rates of Cr(VI) reduction were only marginally accelerated, suggesting that Cr(OH)3(s) coatings did not completely block access of Cr(VI) to reactive surface sites on pyrite. Given the rapid rates of Cr(VI) reduction with pyrite under pH and surface coverage conditions typical of natural environments, we propose that Cr(VI) reduction by pyrite be considered in fate and transport models for Cr in contaminated sediments.