WorldWideScience

Sample records for coastal sediments iron

  1. Iron-mediated anaerobic oxidation of methane in brackish coastal sediments.

    Science.gov (United States)

    Egger, Matthias; Rasigraf, Olivia; Sapart, Célia J; Jilbert, Tom; Jetten, Mike S M; Röckmann, Thomas; van der Veen, Carina; Bândă, Narcisa; Kartal, Boran; Ettwig, Katharina F; Slomp, Caroline P

    2015-01-06

    Methane is a powerful greenhouse gas and its biological conversion in marine sediments, largely controlled by anaerobic oxidation of methane (AOM), is a crucial part of the global carbon cycle. However, little is known about the role of iron oxides as an oxidant for AOM. Here we provide the first field evidence for iron-dependent AOM in brackish coastal surface sediments and show that methane produced in Bothnian Sea sediments is oxidized in distinct zones of iron- and sulfate-dependent AOM. At our study site, anthropogenic eutrophication over recent decades has led to an upward migration of the sulfate/methane transition zone in the sediment. Abundant iron oxides and high dissolved ferrous iron indicate iron reduction in the methanogenic sediments below the newly established sulfate/methane transition. Laboratory incubation studies of these sediments strongly suggest that the in situ microbial community is capable of linking methane oxidation to iron oxide reduction. Eutrophication of coastal environments may therefore create geochemical conditions favorable for iron-mediated AOM and thus increase the relevance of iron-dependent methane oxidation in the future. Besides its role in mitigating methane emissions, iron-dependent AOM strongly impacts sedimentary iron cycling and related biogeochemical processes through the reduction of large quantities of iron oxides.

  2. Sulfur and Iron Cycling in a Coastal Sediment - Radiotracer Studies and Seasonal Dynamics

    DEFF Research Database (Denmark)

    MOESLUND, L.; THAMDRUP, B.; JØRGENSEN, BB

    1994-01-01

    The seasonal variation in sulfate reduction and the dynamics of sulfur and iron geochemistry were studied throughout a year in sediment of Aarhus Bay, Denmark. A radiotracer method for measuring sulfate reduction rates was applied with incubation times down to 15 min and a depth resolution down...... to 2 mm in the oxidized surface layer of the sediment. The radiotracer data were analyzed by a mathematical model which showed that, due to partial, rapid reoxidation of radioactive sulfide during incubation, the actual reduction rates in this layer were probably underestimated 5-fold. In the deeper......, sulfidic zone, measured rates appeared to be correct. Sulfate reduction followed the seasonal variation in temperature with maximum activity at 1-2 cm depth in late summer. In spite of its rapid production, free H2S was detectable in the porewater only below the depth of free Fe2+ at 6-7 cm throughout...

  3. Detection and mapping of the iron ore occurrence in the sea floor sediments in the coastal zone of the Sepetiba Bay. Rio de Janeiro. Brasil

    International Nuclear Information System (INIS)

    Vieira, P.

    2010-01-01

    This work is about the detection and mapping of the iron occurrence in the sea floor sediments in the coastal zone of the Sepetiba Bay. Rio de Janeiro. Brasil. The results of geochemical analysis revealed that the area around the mangrove forest located near the Itacuruca channel, the perpendicular direction to the Muriqui Yacht Club channel and the immediate vicinity of the the Guaiba Island Terminal were respectively the areas of highest iron ore concentration

  4. Cable bacteria control iron-phosphorus dynamics in sediments of a coastal hypoxic basin

    NARCIS (Netherlands)

    Sulu-Gambari, Fatimah; Seitaj, Dorina; Meysman, Filip J.R.; Schauer, Regina; Polerecky, Lubos; Slomp, Caroline P.

    2016-01-01

    Phosphorus is an essential nutrient for life. The release of phosphorus from sediments is critical in sustaining phytoplankton growth in many aquatic systems and is pivotal to eutrophication and the development of bottom water hypoxia. Conventionally, sediment phosphorus release is thought to be

  5. Sulfur and Iron Cycling in a Coastal Sediment - Radiotracer Studies and Seasonal Dynamics

    DEFF Research Database (Denmark)

    MOESLUND, L.; THAMDRUP, B.; JØRGENSEN, BB

    1994-01-01

    to 2 mm in the oxidized surface layer of the sediment. The radiotracer data were analyzed by a mathematical model which showed that, due to partial, rapid reoxidation of radioactive sulfide during incubation, the actual reduction rates in this layer were probably underestimated 5-fold. In the deeper......, sulfidic zone, measured rates appeared to be correct. Sulfate reduction followed the seasonal variation in temperature with maximum activity at 1-2 cm depth in late summer. In spite of its rapid production, free H2S was detectable in the porewater only below the depth of free Fe2+ at 6-7 cm throughout...

  6. Manganese, Iron, and Sulfur Cycling in a Coastal Marine Sediment, Aarhus Bay, Denmark

    DEFF Research Database (Denmark)

    THAMDRUP, B.; FOSSING, H.; JØRGENSEN, BB

    1994-01-01

    -scale measurements showed that it extended to the upper 0-2.5 mm during summer, when the zones of Mn and Fe reduction were compressed towards the surface. Most of the H2S produced precipitated as iron sulfides and S0 by reaction with Fe. Both Fe(III) and a nonsulfur-bound authigenic Fe(II) pool reacted efficiently...... of a diatom spring bloom caused distinct maxima in SRR and Mn2+ at 0.5-1 cm depth within two weeks. In autumn, the reactive Mn oxides were depleted due to a net release of Mn2+ to the water column. Thus, the Mn cycle extended significantly into the water column, while a constant Fe pool over the year suggests...

  7. Coastal sediment dynamics in Spitsbergen

    Science.gov (United States)

    Deloffre, J.; Lafite, R.; Baltzer, A.; Marlin, C.; Delangle, E.; Dethleff, D.; Petit, F.

    2010-12-01

    In arctic knowledge on coastal sediment dynamics and sedimentary processes is limited. The studied area is located in the microtidal Kongsfjorden glacial fjord on the North-western coast of Spitsbergen in the Artic Ocean (79°N). In this area sediment contributions to the coastal zone is provided by small temporary rivers that flows into the fjord. The objectives of this study are to (i) assess the origin and fate of fine-grained particles (sea ice cover on sediment dynamics. The sampling strategy is based on characterization of sediment and SPM (grain-size, X-rays diffraction, SEM images, carbonates and organic matter contents) from the glacier to the coastal zone completed by a bottom-sediment map on the nearshore using side-scan sonar validated with Ekman binge sampling. River inputs (i.e. river plumes) to the coastal zone were punctually followed using CTD (conductivity, temperature, depth and turbidity) profiles. OBS (water level, temperature and turbidity) operating at high-frequency and during at least 1 years (including under sea ice cover) was settled at the mouth of rivers at 10m depth. In the coastal zone the fine-grained sediment deposit is limited to mud patches located at river mouths that originate the piedmont glacier. However a significant amount of sediment originates the coastal glacier located in the eastern part of the fjord via two processes: direct transfer and ice-drop. Results from turbidity measurements show that the sediment dynamics is controlled by river inputs in particular during melting period. During winter sediment resuspension can occurs directly linked to significant wind-events. When the sea ice cover is present (January to April) no sediment dynamics is observed. Sediment processes in the coastal zone of arctic fjords is significant however only a small amount of SPM that originates the river plume settles in the coastal zone; only the coarser material settles at the mouth of the river while the finer one is deposited further

  8. Bacterial chemoautotrophy in coastal sediments

    NARCIS (Netherlands)

    Vasquez Cardenas, D.

    2016-01-01

    A key process in the biogeochemistry of coastal sediments is the reoxidation of reduced intermediates formed during anaerobic mineralization which in part is performed by chemoautotrophic bacteria. These bacteria fix inorganic carbon using the energy derived from reoxidation reactions. However the

  9. Coastal hypoxia and sediment biogeochemistry

    Directory of Open Access Journals (Sweden)

    J. J. Middelburg

    2009-07-01

    Full Text Available The intensity, duration and frequency of coastal hypoxia (oxygen concentration <63 μM are increasing due to human alteration of coastal ecosystems and changes in oceanographic conditions due to global warming. Here we provide a concise review of the consequences of coastal hypoxia for sediment biogeochemistry. Changes in bottom-water oxygen levels have consequences for early diagenetic pathways (more anaerobic at expense of aerobic pathways, the efficiency of re-oxidation of reduced metabolites and the nature, direction and magnitude of sediment-water exchange fluxes. Hypoxia may also lead to more organic matter accumulation and burial and the organic matter eventually buried is also of higher quality, i.e. less degraded. Bottom-water oxygen levels also affect the organisms involved in organic matter processing with the contribution of metazoans decreasing as oxygen levels drop. Hypoxia has a significant effect on benthic animals with the consequences that ecosystem functions related to macrofauna such as bio-irrigation and bioturbation are significantly affected by hypoxia as well. Since many microbes and microbial-mediated biogeochemical processes depend on animal-induced transport processes (e.g. re-oxidation of particulate reduced sulphur and denitrification, there are indirect hypoxia effects on biogeochemistry via the benthos. Severe long-lasting hypoxia and anoxia may result in the accumulation of reduced compounds in sediments and elimination of macrobenthic communities with the consequences that biogeochemical properties during trajectories of decreasing and increasing oxygen may be different (hysteresis with consequences for coastal ecosystem dynamics.

  10. The anaerobic degradation of organic matter in Danish coastal sediments: iron reduction, manganese reduction, and sulfate reduction

    DEFF Research Database (Denmark)

    Canfield, Donald Eugene; Thamdrup, B; Hansen, Jens Würgler

    1993-01-01

    ). In the deep portion of the basin, surface Mn enrichments reached 3.5 wt%, and Mn reduction was the only important anaerobic carbon oxidation process in the upper 10 cm of the sediment. In the less Mn-rich sediments from intermediate depths in the basin, Fe reduction ranged from somewhat less, to far more...... speculate that in shallow sediments of the Skagerrak, surface Mn oxides are present in a somewhat reduced oxidation level (deep basin....

  11. Phosphate solubilizing bacteria: Comparison between coastal and deep sea sediments

    Digital Repository Service at National Institute of Oceanography (India)

    Biche, S.; Pandey, S.; Gonsalves, M.J.B.D.; Das, A.; Mascarenhas-Pereira, M.B.L.; LokaBharathi, P.A.

    in the CIB sediments (r=0.59) than in the coastal sediments (r= 0.22). It is apparent that the enzyme activity in the coastal sediments could be more for P mobilization and in the oligotrophic deep sea it could be both for P and C mobilization....

  12. Trace metals in coastal sediments of Costa Rica

    International Nuclear Information System (INIS)

    Garcia Cespedes, J.; Acuna Gonzalez, J.; Vargas Zamora, J.A.

    2004-01-01

    Marine sediment samples from four coastal ecosystems in Costa Rica were taken between the years 2000-2002 and their iron, lead, copper and zinc concentrations were determined by the atomic absorption technique with flame or graphite furnace. In the Pacific coast, Culebra Bay (Papagayo Gulf), Gulf of Nicoya, and Golfito Bay (Dulce Gulf), were selected as representative sites, and Moin Bay, at the Caribbean coast. Mean metal concentrations for all ecosystems followed the same pattern: Fe> Zn> Cu> Pb. No temporal pattern was found for any metal. Iron and copper mean concentrations were higher in Golfito Bay (5.8% and 87 μg / g, respectively) and lower in Moin Bay (3.4% and 52 μg / g, respectively). Zinc mean concentration was also higher in Golfito Bay (96 μg / g), but lower in Culebra Bay (66 μg / g). Lead mean concentration was higher in Moin Bay (6.4 μg / g) and lower in Culebra Bay (3.0 μg / g). Lead highest concentrations occurred in the Caribbean and in Golfito Bay, and for the rest of the elements the maximum values were found in Golfito Bay. On the basis of data obtained in this work, Culebra Bay was considered a relatively unpolluted location; Golfito Bay was more contaminated, and Moin Bay and the Gulf of Nicoya showed an intermediate condition. (Author) [es

  13. Ecosystem engineering and biodiversity in coastal sediments: posing hypotheses

    NARCIS (Netherlands)

    Bouma, T.J.; Olenin, S.; Reise, K.; Ysebaert, T.

    2009-01-01

    Coastal sediments in sheltered temperate locations are strongly modified by ecosystem engineering species such as marsh plants, seagrass, and algae as well as by epibenthic and endobenthic invertebrates. These ecosystem engineers are shaping the coastal sea and landscape, control particulate and

  14. Coastal sediment elevation change following anthropogenic mangrove clearing

    Science.gov (United States)

    Hayden, Heather L.; Granek, Elise F.

    2015-11-01

    Coastal mangrove forests along tropical shorelines serve as an important interface between land and sea. They provide a physical buffer protecting the coastline from erosion and act as sediment "traps" catching terrestrial sediment, thus preventing smothering of subtidal coral reefs. Coastal development that removes mangrove habitat may impact adjacent nearshore coral reefs through sedimentation and nutrient loading. We examined differences in sediment elevation change between patches of open-coast intact and anthropogenically cleared red mangroves (Rhizophora mangle) on the east side of Turneffe Atoll, Belize, to quantify changes following mangrove clearing. Samples were collected over a 24 month period at five study sites, each containing paired intact (+mangrove) and cleared (-mangrove) plots. Five sediment elevation pins were deployed in each plot: behind areas cleared of mangroves (-mangrove) and behind adjacent intact mangroves (+mangrove). Sediment elevation increased at intact mangrove sites (M = +3.83 mm, SE = 0.95) whereas cleared mangrove areas suffered elevation loss (M = -7.30 mm, SE = 3.38). Mangroves inshore of partial or continuous gaps in the adjacent fringing reefs had higher rates of elevation loss (M = -15.05 mm) than mangroves inshore of continuous fringing reefs (M = -1.90 mm). Our findings provide information on potential effects of mangrove clearing and the role of offshore habitat characteristics on coastal sediment trapping and maintenance of sediment elevation by mangroves. With implications for coastline capacity to adjust to sea level rise, these findings are relevant to management of coastal fringing mangrove forests across the Caribbean.

  15. Assessment of heavy metals concentrations in coastal sediments in ...

    African Journals Online (AJOL)

    EJIRO

    Three kinds of analytical method were used for metals determination and quantification: ... such as copper, zinc, manganese, iron and chromium in Nosy Be sediments, were twice as .... Mean sewage of Mahajanga from Vallon de Meitzinger.

  16. Sediment and toxic contaminant transport modeling in coastal waters

    International Nuclear Information System (INIS)

    Onishi, Y.; Mayer, D.W.; Argo, R.S.

    1982-02-01

    A hydrodynamic model, CAFE-I, a wave refraction model, LO3D, and a sediment and contaminant transport model, FETRA, were selected as tools for evaluating exposure levels of radionuclides, heavy metals, and other toxic chemicals in coastal waters. Prior to the application of these models to the Irish Sea and other coastal waters, the finite element model, FETRA, was tested to demonstrate its ability to simulate sediment and contaminant interactions (e.g., adsorption and desorption), and the mechanisms governing the transport, deposition, and resuspension of contaminated sediments

  17. Comprehensive Sediment Management to Improve Wetland Sustainability in Coastal Louisiana

    Science.gov (United States)

    Khalil, S.; Freeman, A. M.; Raynie, R.

    2016-02-01

    Human intervention has impaired the Mississippi River's ability to deliver sediment to its deltaic wetlands, and as a consequence acute land loss in coastal Louisiana has resulted in an unprecedented ecocatastrophe. Since the 1930s, Louisiana has lost approximately 5,000 square kilometers of coastal land, and is continuing to lose land at the rate of approximately 43 square kilometers/year. This extreme rate of land loss threatens a range of key national assets and important communities. Coastal communities across the world as well as in Louisiana have realized the importance of sediment for the continuation of their very existence in these productive but vulnerable regions. Ecological restoration can only be undertaken on a stable coastline, for which sedimentological restoration is needed. A large-scale effort to restore coastal Louisiana is underway, guided by Louisiana's Comprehensive Master Plan for a Sustainable Coast. This 50-year, $50-billion plan prescribes 109 protection and restoration projects to reduce land loss, maintain and restore coastal environments and sustain communities. Nowhere else has a restoration and protection program of this scale been developed or implemented, and critical to its success is the optimized usage of limited fluvial and offshore sediment resources, and a keen understanding of the complex interactions of various geological/geophysical processes in ecosystem restoration. A comprehensive sediment management plan has been developed to identify and delineate potential sediment sources for restoration, and to provide a framework for managing sediment resources wisely, cost effectively, and in a systematic manner. The Louisiana Sediment Management Plan provides regional strategies for improved comprehensive management of Louisiana's limited sediment resources. Adaptive management via a robust system-wide monitoring plays an important role along with a regional approach for the efficient management of sediment resources.

  18. Challenges in transferring knowledge between scales in coastal sediment dynamics

    Directory of Open Access Journals (Sweden)

    Shari L Gallop

    2015-10-01

    Full Text Available ‘Packaging’ coastal sediment transport into discrete temporal and spatial scale bands is necessary for measurement programs, modelling, and design. However, determining how to best measure and parameterize information, to transfer between scales, is not trivial. An overview is provided of the major complexities in transferring information on coastal sediment transport between scales. Key considerations that recur in the literature include: interaction between sediment transport and morphology; the influence of biota; episodic sediment transport; and recovery time-scales. The influence of bedforms and landforms, as well as sediment-biota interactions, varies with spatio-temporal scale. In some situations, episodic sediment dynamics is the main contributor to long-term sediment transport. Such events can also significantly alter biogeochemical and ecological processes, which interact with sediments. The impact of such episodic events is fundamentally influenced by recovery time-scales, which vary spatially. For the various approaches to scaling (e.g., bottom-up, aggregation, spatial hierarchies, there is a need for fundamental research on the assumptions inherent in each approach.

  19. Wenzhouxiangella sediminis sp. nov. isolated from coastal sediment

    Science.gov (United States)

    A novel Gram-stain-negative, non-spore-forming, no flagellum, facultatively anaerobic, oxidase-negative, catalase- positive, rod-shaped strain, designated XDB06**T, was isolated from coastal sediment of Xiaoshi Island, Weihai, China. Optimal growth occurred at 37 °C, pH 7.5 and with 4.0% (w/v) NaCl....

  20. Understanding coastal morphodynamic patterns from depth-averaged sediment concentration

    NARCIS (Netherlands)

    Ribas, F.; Falques, A.; de Swart, H. E.; Dodd, N.; Garnier, R.; Calvete, D.

    This review highlights the important role of the depth-averaged sediment concentration (DASC) to understand the formation of a number of coastal morphodynamic features that have an alongshore rhythmic pattern: beach cusps, surf zone transverse and crescentic bars, and shoreface-connected sand

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    The relative importance of two dissimilatory nitrate reduction pathways, denitrification (DEN) and dissimilatory nitrate reduction to ammonium (DNRA), was investigated in intact sediment cores from five different coastal marine field sites (Dorum, Aarhus Bight, Mississippi Delta, Limfjord...... reduction was clearly dominated by DEN (59-131% of the total NO3- reduced) rather than by DNRA, irrespective of the sedimentary inventories of electron donors such as organic carbon, sulfide, and iron. Highest ammonium production via DNRA, accounting for up to 8.9% of the total NO3- reduced, was found...... was detected accounting for 37-77% of the total NO3- reduced. These contradictory results might be explained by enhanced NO3- availability for DNRA bacteria in the sediment slurries compared to the core-incubated sediments in which diffusion of NO3- from the water column may only reach DEN bacteria...

  2. Sediment and toxic contaminant transport modeling in coastal waters

    International Nuclear Information System (INIS)

    Onishi, Yasuo; Mayer, D.W.; Argo, R.S.

    1982-01-01

    Models are presented to estimate the migration of toxic contaminants in coastal waters. Ocean current is simulated by the vertically-averaged, finite element, two-demensional model known as CAFE-I with the Galerkin weighted residual technique. The refraction of locally generated waves or swells is simulated by the wave refraction model, LO3D. Using computed current, depth, and wave characteristics, the finite element model, FETRA, simulated sediment and contaminant transport in coastal waters, estuaries and rivers. Prior to the application of these models to the Irish Sea and other coastal waters, the finite element model, FETRA, was tested to demonstrate its ability to simulate sediment and contaminant interaction, and the mechanism governing the transport, deposition, and resuspension of contaminated sediment. Several simple equations such as the unsteady, advection-diffusion equation, the equation for noncohesive-sediment load due to wind-induced waves in offshore and surf zones, and the equation for sediment-radionuclide transport simulation were solved during the preliminary testing of the model. (Kato, T.)

  3. Modeling sediment transport in Qatar: Application for coastal development planning.

    Science.gov (United States)

    Yousif, Ruqaiya; Warren, Christopher; Ben-Hamadou, Radhouan; Husrevoglu, Sinan

    2018-03-01

    Hydrodynamics and sediment transport are key physical processes contributing to habitat structure within the marine environment. Coastal development that results in the alteration of these processes (e.g., changing water flushing and/or sedimentation rates) can have detrimental impacts on sensitive systems. This is a current, relevant issue in Qatar as its coastal regions continue to be developed, not only around the capital of Doha, but in many areas around this Arabian Gulf peninsula. The northeastern Qatari coast is comprised of diverse and sensitive flora and fauna such as seagrass and macroalgae meadows, coral reefs and patches, turtles, and dugongs that tolerate harsh environmental conditions. In the near future, this area may see a rise in anthropogenic activity in the form of coastal development projects. These projects will add to existing natural stresses, such as high temperature, high salinity, and low rates of precipitation. Consequently, there is a need to characterize this area and assess the potential impacts that these anthropogenic activities may have on the region. In the present study, a novel sediment transport model is described and used to demonstrate the potential impact of altering hydrodynamics and subsequent sediment transport along the northeastern Qatar nearshore marine environment. The developed models will be tested using potential scenarios of future anthropogenic activities forecasted to take place in the area. The results will show the effects on water and sediment behavior and provide a scientific approach for key stakeholders to make decisions with respect to the management of the considered coastal zone. Furthermore, it provides a tool and framework that can be utilized in environmental impact assessment and associated hydrodynamic studies along other areas of the Qatari coastal zone. Integr Environ Assess Manag 2018;14:240-251. © 2017 SETAC. © 2017 SETAC.

  4. Controls of Sediment Nitrogen Dynamics in Tropical Coastal Lagoons

    Science.gov (United States)

    Enrich-Prast, Alex; Figueiredo, Viviane; Esteves, Francisco de Assis; Nielsen, Lars Peter

    2016-01-01

    Sediment denitrification rates seem to be lower in tropical environments than in temperate environments. Using the isotope pairing technique, we measured actual denitrification rates in the sediment of tropical coastal lagoons. To explain the low denitrification rates observed at all study sites (<5 μmol N2 m-2 h-1), we also evaluated potential oxygen (O2) consumption, potential nitrification, potential denitrification, potential anammox, and estimated dissimilatory nitrate (NO3-) reduction to ammonium (NH4+; DNRA) in the sediment. 15NO3- and 15NH4+ conversion was measured in oxic and anoxic slurries from the sediment surface. Sediment potential O2 consumption was used as a proxy for overall mineralization activity. Actual denitrification rates and different potential nitrogen (N) oxidation and reduction processes were significantly correlated with potential O2 consumption. The contribution of potential nitrification to total O2 consumption decreased from contributing 9% at sites with the lowest sediment mineralization rates to less than 0.1% at sites with the highest rates. NO3- reduction switched completely from potential denitrification to estimated DNRA. Ammonium oxidation and nitrite (NO2-) reduction by potential anammox contributed up to 3% in sediments with the lowest sediment mineralization rates. The majority of these patterns could be explained by variations in the microbial environments from stable and largely oxic conditions at low sediment mineralization sites to more variable conditions and the prevalences of anaerobic microorganisms at high sediment mineralization sites. Furthermore, the presence of algal and microbial mats on the sediment had a significant effect on all studied processes. We propose a theoretical model based on low and high sediment mineralization rates to explain the growth, activity, and distribution of microorganisms carrying out denitrification and DNRA in sediments that can explain the dominance or coexistence of DNRA and

  5. Shelf-to-basin iron shuttling enhances vivianite formation in deep Baltic Sea sediments

    Science.gov (United States)

    Reed, Daniel C.; Gustafsson, Bo G.; Slomp, Caroline P.

    2016-01-01

    Coastal hypoxia is a growing and persistent problem largely attributable to enhanced terrestrial nutrient (i.e., nitrogen and phosphorus) loading. Recent studies suggest phosphorus removal through burial of iron (II) phosphates, putatively vivianite, plays an important role in nutrient cycling in the Baltic Sea - the world's largest anthropogenic dead zone - yet the dynamics of iron (II) phosphate formation are poorly constrained. To address this, a reactive-transport model was used to reconstruct the diagenetic and depositional history of sediments in the Fårö basin, a deep anoxic and sulphidic region of the Baltic Sea where iron (II) phosphates have been observed. Simulations demonstrate that transport of iron from shelf sediments to deep basins enhances vivianite formation while sulphide concentrations are low, but that pyrite forms preferentially over vivianite when sulphate reduction intensifies due to elevated organic loading. Episodic reoxygenation events, associated with major inflows of oxic waters, encourage the retention of iron oxyhydroxides and iron-bound phosphorus in sediments, increasing vivianite precipitation as a result. Results suggest that artificial reoxygenation of the Baltic Sea bottom waters could sequester up to 3% of the annual external phosphorus loads as iron (II) phosphates, but this is negligible when compared to potential internal phosphorus loads due to dissolution of iron oxyhydroxides when low oxygen conditions prevail. Thus, enhancing vivianite formation through artificial reoxygenation of deep waters is not a viable engineering solution to eutrophication in the Baltic Sea. Finally, simulations suggest that regions with limited sulphate reduction and hypoxic intervals, such as eutrophic estuaries, could act as important phosphorus sinks by sequestering vivianite. This could potentially alleviate eutrophication in shelf and slope environments.

  6. Sediment quality in the north coastal basin of Massachusetts, 2003

    Science.gov (United States)

    Breault, Robert F.; Ashman, Mary S.; Heath, Douglas

    2004-01-01

    The U.S. Geological Survey, in cooperation with the Massachusetts Department of Environmental Protection, completed a reconnaissance-level study of bottom-sediment quality in selected lakes, rivers, and estuaries in the North Coastal Basin of Massachusetts. Bottom-sediment grab samples were collected from 20 sites in the North River, Lake Quannapowitt, Saugus River, Mill River, Shute Brook, Sea Plane Basin, Pines River, and Bear Creek. The samples were tested for various types of potentially harmful contaminants? including 33 elements, 17 polyaromatic hydrocarbons (PAHs), 22 organochlorine pesticides, and 7 polychlorinated biphenyl (PCB) mixtures (Aroclors)?to benthic organisms (bottom-dwelling) and humans. The results were compared among sampling sites, to background concentrations, and to concen-trations measured in other urban rivers, and sediment-quality guidelines were used to predict toxicity at the sampling sites to benthic organisms and humans. Because there are no standards for human toxicity for aquatic sediment, standards for contaminated upland soil were used. Contaminant concentrations measured in sediment collected from the North Coastal Basin generally were equal to or greater than concentrations in sediment from uncontaminated rivers throughout New England. Contaminants in North Coastal Basin sediment with elevated concentrations (above back-ground levels) included arsenic, chromium, copper, lead, nickel, and zinc, some of the PAHs, dichlorodiphenyltrichloro-ethane (DDT) and its metabolites, and dieldrin. No PCBs were measured above the detection limits. Measured concentrations of arsenic, chromium, and lead were also generally greater than those measured in other urban rivers throughout the conter-minous United States. With one exception (arsenic), local con-centrations measured in sediment samples collected from the North Coastal Basin were lower than concentrations measured in sediment collected from two of three urban rivers draining to Boston

  7. Influence of iron redox transformations on plutonium sorption to sediments

    Energy Technology Data Exchange (ETDEWEB)

    Hixon, A.E.; Powell, B.A. [Environmental Engineering and Earth Sciences, Clemson Univ., Clemson, SC (United States); Hu, Y.J.; Nitsche, H. [Dept. of Chemistry, Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab., Berkeley, CA (United States); Kaplan, D.I. [Savannah River National Lab., Aiken, SC (United States); Kukkadapu, R.K.; Qafoku, O. [Pacific Northwest National Lab., Richland, WA (United States)

    2010-07-01

    Plutonium subsurface mobility is primarily controlled by its oxidation state, which in turn is loosely coupled to the oxidation state of iron in the system. Experiments were conducted to examine the effect of sediment iron mineral composition and oxidation state on plutonium sorption and reduction. A pH 6.3 vadose zone sediment containing iron oxides and iron-containing phyllosilicates was treated with various complexants (ammonium oxalate) and reductants (hydroxylamine hydrochloride and dithionite-citrate-bicarbonate (DCB)) to selectively leach and/or reduce iron oxide and phyllosilicate/clay Fe(III). {sup 57}Fe-Moessbauer spectroscopy was used to identify initial iron mineral composition of the sediment and monitor dissolution and reduction of iron oxides and reduction of phyllosilicate Fe(III). {sup 57}Fe-Moessbauer spectroscopy showed that the Fe-mineral composition of the untreated sediment is: 25-30% hematite, 60-65% small-particle/Al-goethite, and < 10% Fe(III) in phyllosilicate; there was no detectable Fe(II). Upon reduction with a strong chemical reductant (dithionite-citrate-bicarbonate buffer), much of the hematite and goethite was removed. Partial reduction of phyllosilicate Fe(III) was evident in the sediments subjected to DCB treatment. Sorption of Pu(V) was monitored over one week for the untreated and each of five treated sediment fractions. Plutonium oxidation state speciation in the aqueous and solid phases was monitored using solvent extraction, coprecipitation, and XANES. The rate of sorption appears to correlate with the fraction of Fe(II) in the sediment (untreated or treated). Pu(V) was the only oxidation state measured in the aqueous phase, irrespective of treatment, whereas Pu(IV) and much smaller amounts of Pu(V) and Pu(VI) were measured in the solid phase. Surface-mediated reduction of Pu(V) to Pu(IV) occurred in treated and untreated sediment samples; Pu(V) remained on untreated sediment surface for two days before reducing to Pu

  8. Cadmium distribution in coastal sediments and mollusks of the US

    International Nuclear Information System (INIS)

    Apeti, Dennis A.; Lauenstein, Gunnar G.; Riedel, Gerhardt F.

    2009-01-01

    Cadmium (Cd) concentrations in the coastal United States were assessed using the National Status and Trends (NS and T) Mussel Watch dataset, which is based on the analysis of sediments and bivalves collected from 280 sites since 1986. Using the 1997 sediment data, Pearson correlation (r = 0.44, p < 0.0001) suggested that Cd distributions in sediment can, be to some extent, explained by the proximity of sites to population centers. The 2003 tissue data indicated that 'high' Cd concentrations (greater than 5.6 μg/g dry weights [dw] for mussel and 5.4 μg/g dw for oysters) were related to salinity along the East and Gulf coasts. Along the West coast, however, these 'high' sites appeared to be related to upwelling phenomenon. Additionally, sedimentary diagenesis was found to be the most likely explanation of why sediment and mollusk Cd content were not well correlated.

  9. Lead distribution in coastal and estuarine sediments around India

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, S.; Chakraborty, P.; Nath, B.N.

    . Trace element geochemical associations in the Arabian Gulf. Mar. Pollut. Bull. 17, 353–356. doi:10.1016/0025-326X(86)90247-X Achyuthan, H., Richardmohan, D., Srinivasalu, S., 2002a. Trace metals concentrations in the sediment cores of estuary... in the coastal sediment of chennai coast. IIOAB J. 3, 12–18. Ray, A.K., Tripathy, S.C., Patra, S., Sarma, V. V, 2006. Assessment of Godavari estuarine mangrove ecosystem through trace metal studies. Environ. Int. 32, 219–223. Reddy, M.S., Basha, S., Sravan...

  10. REVIEW OF COASTAL CHARACTERISTICS OF IRON SAND DEPOSITS IN CILACAP CENTRAL JAVA

    Directory of Open Access Journals (Sweden)

    Hananto Kurnio

    2017-07-01

    Full Text Available Mineable iron sand deposits in Cilacap – southern coastal area of Central Java have certain coastal characteristics that need to be studied in order to understand its depositional environment. With the knowledge of such environment, it can be applied to look for other places prospective of iron sand deposits that have the same characteristics especially recently when Cilacap’s deposits were almost depleted. Coastal characteristics of iron sand deposit in Cilacap is shown by successive sandy beach ridges separated by marshy valleys typical of prograded coasts and by dunes of sand elongated parallel to the shore line with elevation varies from 0 m to 15 m above sea level. The iron sand deposit was derived from denudation of andesite and “Old Andesite Formation” enriched in magnetite and ilmenite minerals in the steep elevated and deeply weathered rock hinterlands of Cilacap. High sediment loads of Serayu Basin in the hinterland (3,500-4,500 ton/km2/year; Citarum River basin only 800-1,200 ton/km2/year was causing extensive deposition of iron sand in the coastal zone. Key words: coast, characteristic, iron sand, Cilacap Endapan pasir besi yang dapat ditambang di Cilacap – pesisir selatan Jawa Tengah memiliki karakteristik pantai tertentu yang perlu dikaji agar dapat dipahami lingkungan pengendapannya. Dengan pengetahuan tentang lingkungan pengendapan tersebut, dapat diterapkan untuk mencari daerah-daerah lain prospek endapan pasir besi yang memiliki karakteristik yang sama terutama pada akhir-akhir ini ketika endapan Cilacap akan habis. Karakteristik pantai endapan pasir besi di Cilacap dicirikan oleh urutan pematang pantai berpasir yang dipisahkan oleh lembah-lembah berawa khas pantai maju dan oleh gumuk-gumuk pasir memanjang sejajar dengan garis pantai dengan ketinggian bervariasi dari 0 m hingga 15 m dari muka laut. Endapan pasir besi di daerah ini berasal dari proses denudasi andesit dan “Formasi Andesit

  11. Salmonella rarely detected in Mississippi coastal waters and sediment.

    Science.gov (United States)

    Carr, M R; Wang, S Y; McLean, T I; Flood, C J; Ellender, R D

    2010-12-01

    Standards for the rapid detection of individual pathogens from environmental samples have not been developed, but in their absence, the use of molecular-based detection methods coupled with traditional microbiology techniques allows for rapid and accurate pathogen detection from environmental waters and sediment. The aim of this research was to combine the use of enrichment with PCR for detection of Salmonella in Mississippi coastal waters and sediment and observe if that presence correlated with levels of enterococci and climatological variables. Salmonella were primarily found in samples that underwent nutrient enrichment and were present more frequently in freshwater than marine waters. Salmonella were detected infrequently in marine and freshwater sediments. There was a significant positive correlation between the presence of detectable Salmonella and the average enterococcal count. An inverse relationship, however, was observed between the frequency of detection and the levels of salinity, turbidity and sunlight exposure. Results from this study indicated the presence of Salmonella in Mississippi coastal waters, and sediments are very low with significant differences between freshwater and marine environments. Using pathogenic and novel nonpathogenic molecular markers, Salmonella do not appear to be a significant pathogenic genus along the Mississippi Coast. © 2010 The Authors. Journal of Applied Microbiology © 2010 The Society for Applied Microbiology.

  12. Rapid Sediment Accumulation Results in High Methane Effluxes from Coastal Sediments.

    Directory of Open Access Journals (Sweden)

    Matthias Egger

    Full Text Available Globally, the methane (CH4 efflux from the ocean to the atmosphere is small, despite high rates of CH4 production in continental shelf and slope environments. This low efflux results from the biological removal of CH4 through anaerobic oxidation with sulfate in marine sediments. In some settings, however, pore water CH4 is found throughout the sulfate-bearing zone, indicating an apparently inefficient oxidation barrier for CH4. Here we demonstrate that rapid sediment accumulation can explain this limited capacity for CH4 removal in coastal sediments. In a saline coastal reservoir (Lake Grevelingen, The Netherlands, we observed high diffusive CH4 effluxes from the sediment into the overlying water column (0.2-0.8 mol m-2 yr-1 during multiple years. Linear pore water CH4 profiles and the absence of an isotopic enrichment commonly associated with CH4 oxidation in a zone with high rates of sulfate reduction (50-170 nmol cm-3 d-1 both suggest that CH4 is bypassing the zone of sulfate reduction. We propose that the rapid sediment accumulation at this site (~ 13 cm yr-1 reduces the residence time of the CH4 oxidizing microorganisms in the sulfate/methane transition zone (< 5 years, thus making it difficult for these slow growing methanotrophic communities to build-up sufficient biomass to efficiently remove pore water CH4. In addition, our results indicate that the high input of organic matter (~ 91 mol C m-2 yr-1 allows for the co-occurrence of different dissimilatory respiration processes, such as (acetotrophic methanogenesis and sulfate reduction in the surface sediments by providing abundant substrate. We conclude that anthropogenic eutrophication and rapid sediment accumulation likely increase the release of CH4 from coastal sediments.

  13. 226Ra chronology of a coastal marine sediment

    International Nuclear Information System (INIS)

    Koide, M.; Bruland, K.; Goldberg, E.D.

    1976-01-01

    Unsupported 226 Ra (tsub (1/2) = 1620 years) in marine sediments can provide a basis for measuring rates of accumulation of the order of centimeters per thousand years. The excess radium apparently enters the sediments incorporated in phytoplankton. The sensitivity of the method depends upon the initial value of the unsupported 226 Ra and of the value of 230 Th, a parent of 226 Ra, in the sedimentary components. 226 Ra dating was applied to a sediment taken from the slope of the San Clemente Basin in the Southern California coastal region. Rates of sedimentation over two half-lives of the nuclide were found to be either 5.2 or 5.3 cm/1000 years depending upon which of two models for the geochronology is used. One model assumes that the 230 Th brings to the deposit an amount of 226 Ra in equilibrium with it. The other is based upon the growth of the 226 Ra from the 230 Th in the sedimentary components. 238+239 Pu and 210 Pb levels in the upper strata indicated sedimentation rates of the order of 100-500 cm/1000 years, i.e. much faster accumulations. It is suggested that these derived rates are spurious and reflect bioturbative activities of surface-living organisms. (Auth.)

  14. SEDIMENTATION IN PACIFIC NORTHWEST COASTAL STREAMS -- EVIDENCE FROM REGIONAL SURVEY OF BED SUBSTRATE SIZE AND STABILITY

    Science.gov (United States)

    Excessive erosion, transport and deposition of sediment are major problems in streams and rivers throughout the United States. We examined evidence of anthropogenic sedimentation in Oregon and Washington coastal streams using relatively rapid measurements taken from surveys duri...

  15. Geochemical peculiarities of marine sediment in coastal areas of India

    International Nuclear Information System (INIS)

    Gothankar, S.S.; Jha, S.K.; Tripathi, R.M.

    2014-01-01

    To understand the impact of anthropogenic activity on coastal marine environment, sediment samples were collected covering the west and east coast of India. The elemental concentration was determined using EDXRF technique. The east coast showed lower Rb/Sr ratio reflecting higher fraction of biogenic deposits, the higher ratio at the west coast reflects higher fraction of terrigenous detritus. The concentration of Pb and Ni was found higher at Rameshwaram and Okha respectively. The result indicates the impact of land based source of pollutant in few locations due to the anthropogenic activities. (author)

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

    DEFF Research Database (Denmark)

    Schippers, A.; Jørgensen, BB

    2002-01-01

    as substrates and NO3- as electron acceptor, in the presence of (FeS2)-Fe-55, to test for co-oxidation of FeS2, but an anaerobic microbial dissolution of (FeS2)-Fe-55, could not been detected. FeS2 and FeS were not oxidized by amorphous Fe(III) oxide in the presence of Fe-complexing organic compounds......Pyrite (FeS2) and iron monosulfide (FeS) play a central role in the sulfur and iron cycles of marine sediments, They may be buried in the sediment or oxidized by O-2 after transport by bioturbation to the sediment surface. FeS2 and FeS may also be oxidized within the anoxic sediment in which NO3...... marine sediments and incubated at different temperatures for > 1 yr. Bacteria could not be enriched with FeS2 as substrate or with FeS and amorphous Fe(III) oxide. With FeS and NO3-, 14 enrichments were obtained. One of these enrichments was further cultivated anaerobically with Fe2+ and S-0...

  17. Radiological responses of different types of Egyptian Mediterranean coastal sediments

    Energy Technology Data Exchange (ETDEWEB)

    El-Gamal, A., E-mail: ayman_elgamal@yahoo.co [Department of Oceanography, Coastal Research Institute, National Water Research Center, 15 Elpharaana St., Elshallalat, Postal code 21514, Alexandria (Egypt); Rashad, M. [Land and Water Technologies Department, Arid Land Cultivation and Development Research Institute, Mubarak City for Scientific Research, Burg El-Arab, Alexandria (Egypt); Ghatass, Z. [Department of Environmental Studies, Institute of Graduate Studies and Research, Alexandria University, Alexandria (Egypt)

    2010-08-15

    The aim of this study was to identify gamma self-absorption correction factors for different types of Egyptian Mediterranean coastal sediments. Self-absorption corrections based on direct transmission through different thicknesses of the most dominant sediment species have been tested against point sources with gamma-ray energies of {sup 241}Am, {sup 137}Cs and {sup 60}Co with 2% uncertainties. Black sand samples from the Rashid branch of the Nile River quantitatively absorbed the low energy of {sup 241}Am through a thickness of 5 cm. In decreasing order of gamma energy self-absorption of {sup 241}Am, the samples under investigation ranked black sand, Matrouh sand, Sidi Gaber sand, shells, Salloum sand, and clay. Empirical self-absorption correction formulas were also deduced. Chemical analyses such as pH, CaCO{sub 3}, total dissolved solids, Ca{sup 2+}, Mg{sup 2+}, CO{sub 3}{sup 2-}, HCO{sub 3}{sup -} and total Fe{sup 2+} have been carried out for the sediments. The relationships between self absorption corrections and the other chemical parameters of the sediments were also examined.

  18. Radiological responses of different types of Egyptian Mediterranean coastal sediments

    Science.gov (United States)

    El-Gamal, A.; Rashad, M.; Ghatass, Z.

    2010-08-01

    The aim of this study was to identify gamma self-absorption correction factors for different types of Egyptian Mediterranean coastal sediments. Self-absorption corrections based on direct transmission through different thicknesses of the most dominant sediment species have been tested against point sources with gamma-ray energies of 241Am, 137Cs and 60Co with 2% uncertainties. Black sand samples from the Rashid branch of the Nile River quantitatively absorbed the low energy of 241Am through a thickness of 5 cm. In decreasing order of gamma energy self-absorption of 241Am, the samples under investigation ranked black sand, Matrouh sand, Sidi Gaber sand, shells, Salloum sand, and clay. Empirical self-absorption correction formulas were also deduced. Chemical analyses such as pH, CaCO 3, total dissolved solids, Ca 2+, Mg 2+, CO 32-, HCO 3- and total Fe 2+ have been carried out for the sediments. The relationships between self absorption corrections and the other chemical parameters of the sediments were also examined.

  19. Heavy Metals Contamination in Coastal Sediments of Karachi, Pakistan

    Science.gov (United States)

    Siddique, A.; Mumtaz, M.; Zaigham, N. A.; Mallick, K. A.; Saied, S.; Khwaja, H. A.

    2008-12-01

    Toxic compounds such as heavy metals exert chronic and lethal effects in animals, plants, and human health. With the rapid industrialization, urbanization, and economic development in Karachi, heavy metals are continuing to be introduced to estuarine and coastal environment through rivers, runoff and land-based point sources. Pollution in the Karachi coastal region (167 km long) is mainly attributed to Lyari and Malir Rivers flowing through the city of Karachi. Both rivers are served by various channels of domestic and industrial wastes carrying more than 300 million gallons per day untreated effluent of 6000 industries and ultimately drain into the beaches of Arabian Sea. Concentrations of selected heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in surface sediments from eighty-eight sites in Karachi coastal region were studied in order to understand metal contamination due to industrialization, urbanization, and economic development in Karachi. Sediment samples were collected in 2005 and 2006. We have found that heavy metal concentrations in surface sediments varied from 0.006 to 24.3 ug/g for Cd, 5.1 to 95 ug/g for Co, 2.9 to 571 ug/g for Cr, 6.9 to 272 ug/g for Cu, 0.55 to 6.5% for Fe, 1.2 to 318 ug/g for Mn, 7.5 to 75 ug/g for Ni, 6.3 to 121 ug/g for Pb, and 3.3 to 389 ug/g for Zn. Enrichment factors (EFs) were calculated to assess whether the concentrations observed represent background or contaminated levels. The highest levels of metals were found to be at the confluence of the Lyari and Malir River streams at the Arabian Sea, indicating the impact of the effluents of the highly urbanized and industrialized city of Karachi. Furthermore, this study assessed heavy metal toxicity risk with the application of Sediment Quality Guideline (SQG) indices (effect range low/effect range median values, ERL/ERM). Results indicated that the potential toxicity of marine environment can cause adverse biological effects to the biota directly and the human health

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

    Science.gov (United States)

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

    2006-12-01

    the sulfate reduction in the 0-2 cm and 5-9 cm layer, respectively. Together acetate, lactate, propionate and isobutyrate accounted for 21 and 52% of the sulfate reduction, in the 0-2 cm and 5-9 cm layer, respectively. Assigning all acetate and lactate turnover in the selenate inhibited samples, these two VFA account for less than 10 and 2%, respectively, of the iron reduction in the 0-2 cm layer. Thus, 67 and 48% of the terminal oxidation in the 0-2cm and 5-9 cm layer must be driven by electron donors other than the investigated VFA. The sulfate reduction rates as well as the VFA turnover rates were at the lower end of reported rates from similar studies, mostly measured in temperate sites (e.g. [2-4, 6, 7]). Comparing a series of studies with different in situ temperatures shows, parameters other than in situ temperature seem to be more important in determining the sulfate reduction and VFA turnover rates. [1] Thamdrup, B. (2000) Bacterial manganese and iron reduction in aquatic sediments, 41-84 pp. Kluwer Academic / Plenum Publ., New York. [2] Parkes, R.J., Gibson, G.R., Mueller-Harvey, I., Buckingham, W.J. and Herbert, R.A. (1989) J. Gen. Microbiol. 135, 175-187. [3] Christensen, D. (1984) Limnol. Oceanogr. 29, 189-192. [4] Shaw, D.G. and McIntosh, D.J. (1990) Estuarine Coastal & Shelf Science 31, 775-788. [5] Levitus, S. and Boyer, T. (1994) World Ocean Atlas, pp. US Department of Commerce, Washington, DC. [6] Kristensen, E., King, G.M., Holmer, M., Banta, G.T., Jensen, M.H., Hansen, K. and Bussarawit, N. (1994) Mar. Ecol.-Prog. Ser. 109, 245-255. [7] Wellsbury, P. and Parkes, R.J. (1995) FEMS Microbiol. Ecol. 17, 85-94.

  1. Mercury speciation in coastal sediments from the central east coast of India by modified BCR method.

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, P.; Babu, P.V.R.; Vudamala, K.; Ramteke, D.; Chennuri, K.

    pervasiveness and adverse effects on wildlife and human health (US EPA, 1997). The high biomagnifications rate of Hg in food chain, makes this metal of the most environmental concern (Fitzgerald et al., 2007; Morel et al., 1998). Global oceans, coastal zones... been reported that coastal sediments act both as a sink and source for toxic metals (Chakraborty et al., 2012b). Sediment contamination in the coastal areas is a major environmental issue because of its potential toxic effects on biological resources...

  2. Pathways for arsenic from sediments to groundwater to streams: Biogeochemical processes in the Inner Coastal Plain, New Jersey, USA

    Science.gov (United States)

    Barringer, Julia L.; Mumford, Adam; Young, Lily Y.; Reilly, Pamela A.; Bonin, Jennifer L.; Rosman, Robert

    2010-01-01

    The Cretaceous and Tertiary sediments that underlie the Inner Coastal Plain of New Jersey contain the arsenic-rich mineral glauconite. Streambed sediments in two Inner Coastal Plain streams (Crosswicks and Raccoon Creeks) that traverse these glauconitic deposits are enriched in arsenic (15–25 mg/kg), and groundwater discharging to the streams contains elevated levels of arsenic (>80 μg/L at a site on Crosswicks Creek) with arsenite generally the dominant species. Low dissolved oxygen, low or undetectable levels of nitrate and sulfate, detectable sulfide concentrations, and high concentrations of iron and dissolved organic carbon (DOC) in the groundwater indicate that reducing environments are present beneath the streambeds and that microbial activity, fueled by the DOC, is involved in releasing arsenic and iron from the geologic materials. In groundwater with the highest arsenic concentrations at Crosswicks Creek, arsenic respiratory reductase gene (arrA) indicated the presence of arsenic-reducing microbes. From extracted DNA, 16s rRNA gene sequences indicate the microbial community may include arsenic-reducing bacteria that have not yet been described. Once in the stream, iron is oxidized and precipitates as hydroxide coatings on the sediments. Arsenite also is oxidized and co-precipitates with or is sorbed to the iron hydroxides. Consequently, dissolved arsenic concentrations are lower in streamwater than in the groundwater, but the arsenic contributed by groundwater becomes part of the arsenic load in the stream when sediments are suspended during high flow. A strong positive relation between concentrations of arsenic and DOC in the groundwater samples indicates that any process—natural or anthropogenic—that increases the organic carbon concentration in the groundwater could stimulate microbial activity and thus increase the amount of arsenic that is released from the geologic materials.

  3. Application of Long Distance Conveyance (LDC) of Dredged Sediments to Louisiana Coastal Restoration

    Science.gov (United States)

    2011-01-01

    generally use some type of bucket for digging the sediment, then hoist or boom the load to the surface. Most common hydraulic methods use a centrifugal...sediment. The loaded bucket is hoisted to the surface and side dumped into a transportation unit, or into the disposal site. Transportation units are...Conveyance (LDC) of Dredged Sediments to Louisiana Coastal Restoration Timothy Welp Coastal and Hydraulics Laboratory U.S. Army Engineer Research

  4. Tidal and longshore sediment transport associated to a coastal structure

    Science.gov (United States)

    Cuadrado, Diana G.; Gómez, Eduardo A.; Ginsberg, S. Susana

    2005-01-01

    In order to understand the subtidal marine dynamics relative to the coastal engineering works in the Bahía Blanca Estuary (Argentina), the balance of sediment transport caused by tidal currents was estimated in the Puerto Rosales area and compared with the predicted potential littoral transport. The breaking wave height used in the littoral drift calculation was estimated after applying different wave transforming procedures over the deepwater wave which was predicted by the occurrence of predominant wind, blowing long enough in an essentially constant direction over a fetch. The effect of a breakwater on currents and circulation was studied by bathymetric and side-scan sonar records, sedimentology, and tidal current measurements. Different modes of transport occur on either sides of the breakwater. On the east side, longshore transport is the principal mode, and on the west side, tidal transport is predominant.

  5. Cadmium, lead and organic matter distribution in coastal sediment from the Adriatic Sea

    International Nuclear Information System (INIS)

    Ujevic, I.; Bogner, D.; Baric, A.

    1999-01-01

    The spatial distribution of Cd, and Pb has been studied in surface sediments of the eastern Adriatic coastal region. In addition, Pb concentration has been determined in long sediment cores dating back to pre-industrial time. The results indicate that trace metal concentrations in surface sediment layer depend both on pollution sources, and on local characteristics of the marine and terrestrial environment. Generally, most of the concentrations are not high revealing that the coastal area is not heavily polluted. Granulometric and geochemical data indicate the existence of some differences between sediments formed in the vicinity of fresh water input and sediments from areas without fresh water input. (author)

  6. Effect of biostimulation on the microbial community in PCB-contaminated sediments through periodic amendment of sediment with iron.

    Science.gov (United States)

    Srinivasa Varadhan, A; Khodadoust, Amid P; Brenner, Richard C

    2011-10-01

    Reductive dehalogenation of polychlorinated biphenyls (PCBs) by indigenous dehalorespiring microorganisms in contaminated sediments may be enhanced via biostimulation by supplying hydrogen generated through the anaerobic corrosion of elemental iron added to the sediment. In this study, the effect of periodic amendment of sediment with various dosages of iron on the microbial community present in sediment was investigated using phospholipid fatty acid analysis (PLFA) over a period of 18 months. Three PCB-contaminated sediments (two freshwater lake sediments and one marine sediment) were used. Signature biomarker analysis of the microbial community present in all three sediments revealed the enrichment of Dehalococcoides species, the population of which was sustained for a longer period of time when the sediment microcosms were amended with the lower dosage of iron (0.01 g iron per g dry sediment) every 6 months as compared to the blank system (without iron). Lower microbial stress levels were reported for the system periodically amended with 0.01 g of iron per g dry sediment every 6 months, thus reducing the competition from other hydrogen-utilizing microorganisms like methanogens, iron reducers, and sulfate reducers. The concentration of hydrogen in the system was found to be an important factor influencing the shift in microbial communities in all sediments with time. Periodic amendment of sediment with larger dosages of iron every 3 months resulted in the early prevalence of Geobacteraceae and sulfate-reducing bacteria followed by methanogens. An average pH of 8.4 (range of 8.2-8.6) and an average hydrogen concentration of 0.75% (range of 0.3-1.2%) observed between 6 and 15 months of the study were found to be conducive to sustaining the population of Dehalococcoides species in the three sediments amended with 0.01 g iron per g dry sediment. Biostimulation of indigenous PCB dechlorinators by the periodic amendment of contaminated sediments with low dosages of

  7. Remote Sensing of Suspended Sediments and Shallow Coastal Waters

    Science.gov (United States)

    Li, Rong-Rong; Kaufman, Yoram J.; Gao, Bo-Cai; Davis, Curtiss O.

    2002-01-01

    Ocean color sensors were designed mainly for remote sensing of chlorophyll concentrations over the clear open oceanic areas (case 1 water) using channels between 0.4 and 0.86 micrometers. The Moderate Resolution Imaging Spectroradiometer (MODIS) launched on the NASA Terra and Aqua Spacecrafts is equipped with narrow channels located within a wider wavelength range between 0.4 and 2.5 micrometers for a variety of remote sensing applications. The wide spectral range can provide improved capabilities for remote sensing of the more complex and turbid coastal waters (case 2 water) and for improved atmospheric corrections for Ocean scenes. In this article, we describe an empirical algorithm that uses this wide spectral range to identifying areas with suspended sediments in turbid waters and shallow waters with bottom reflections. The algorithm takes advantage of the strong water absorption at wavelengths longer than 1 micrometer that does not allow illumination of sediments in the water or a shallow ocean floor. MODIS data acquired over the east coast of China, west coast of Africa, Arabian Sea, Mississippi Delta, and west coast of Florida are used in this study.

  8. The release of dissolved nutrients and metals from coastal sediments due to resuspension

    Science.gov (United States)

    Kalnejais, Linda H.; Martin, William R.; Bothner, Michael H.

    2010-01-01

    Coastal sediments in many regions are impacted by high levels of contaminants. Due to a combination of shallow water depths, waves, and currents, these sediments are subject to regular episodes of sediment resuspension. However, the influence of such disturbances on sediment chemistry and the release of solutes is poorly understood. The aim of this study is to quantify the release of dissolved metals (iron, manganese, silver, copper, and lead) and nutrients due to resuspension in Boston Harbor, Massachusetts, USA. Using a laboratory-based erosion chamber, a range of typical shear stresses was applied to fine-grained Harbor sediments and the solute concentration at each shear stress was measured. At low shear stress, below the erosion threshold, limited solutes were released. Beyond the erosion threshold, a release of all solutes, except lead, was observed and the concentrations increased with shear stress. The release was greater than could be accounted for by conservative mixing of porewaters into the overlying water, suggesting that sediment resuspension enhances the release of nutrients and metals to the dissolved phase. To address the long-term fate of resuspended particles, samples from the erosion chamber were maintained in suspension for 90. h. Over this time, 5-7% of the particulate copper and silver was released to the dissolved phase, while manganese was removed from solution. Thus resuspension releases solutes both during erosion events and over a longer timescale due to reactions of suspended particles in the water column. The magnitude of the annual solute release during erosion events was estimated by coupling the erosion chamber results with a record of bottom shear stresses simulated by a hydrodynamic model. The release of dissolved copper, lead, and phosphate due to resuspension is between 2% and 10% of the total (dissolved plus particulate phase) known inputs to Boston Harbor. Sediment resuspension is responsible for transferring a significant

  9. Concentration-dependent sedimentation properties of ferritin: implications for estimation of iron contents of serum ferritins

    International Nuclear Information System (INIS)

    Niitsu, Y.; Adachi, C.; Takahashi, F.; Goto, Y.; Kohgo, Y.; Urushizaki, I.; Listowsky, I.

    1985-01-01

    Serum ferritins from various sources sedimented at lower densities than tissue ferritins in sucrose gradient centrifugation systems. The sedimentation patterns of ferritins, however, were shown to be dependent on the concentration of the protein; as the concentration decreased the protein appeared to sediment at lower densities. Thus, at the low concentration levels usually used for analysis of serum ferritin, tissue ferritins also sedimented in the same lower density regions. Iron labeling experiments indicated that the sedimentation changes upon dilution were not due to release of iron or was there any indication that the protein dissociated into subunits. The anomalous sedimentation behavior of serum ferritin should therefore not be interpreted in terms of its iron content. The disclosure that serum ferritins may have full complements of iron is counter to the prevalent view that serum ferritins are low iron forms and has potential implications with regard to the sources and possible function of this protein in the circulation

  10. Evolution of radioactive dose rates in fresh sediment deposits along coastal rivers draining Fukushima contamination plume.

    Science.gov (United States)

    Evrard, Olivier; Chartin, Caroline; Onda, Yuichi; Patin, Jeremy; Lepage, Hugo; Lefèvre, Irène; Ayrault, Sophie; Ottlé, Catherine; Bonté, Philippe

    2013-10-29

    Measurement of radioactive dose rates in fine sediment that has recently deposited on channel bed-sand provides a solution to address the lack of continuous river monitoring in Fukushima Prefecture after Fukushima Dai-ichi nuclear power plant (FDNPP) accident. We show that coastal rivers of Eastern Fukushima Prefecture were rapidly supplied with sediment contaminated by radionuclides originating from inland mountain ranges, and that this contaminated material was partly exported by typhoons to the coastal plains as soon as by November 2011. This export was amplified during snowmelt and typhoons in 2012. In 2013, contamination levels measured in sediment found in the upper parts of the catchments were almost systematically lower than the ones measured in nearby soils, whereas their contamination was higher in the coastal plains. We thereby suggest that storage of contaminated sediment in reservoirs and in coastal sections of the river channels now represents the most crucial issue.

  11. 210Pb sediment dating in coastal transition zones: tropical saltmarshes.

    Science.gov (United States)

    Ruiz-Fernandez, A. C.; Sanchez-Cabeza, J. A.; Carnero-Bravo, V.; Perez-Bernal, L. H.

    2016-12-01

    Sea level rise (SLR) is one of the climate change effects expected to have the largest impact on coastal environments. SLR rates are not uniform around the planet and, therefore, local and regional data and trends are needed for proper adaptation plans. As long term monitoring stations of SLR are very scarce in most of the world, SLR trends obtained from 210Pb-dated sediment cores from tropical saltmarshes have become a practical alternative to obtain SLR trends within the past century, under the assumption that these ecosystems accrete at a similar rate to SLR. However, tropical saltmarshes are challenging environments for 210Pb dating: they are regularly dry, intermittently covered by seawater only during the highest tides, and sedimentary records often reflect the transition between terrestrial and marine environments (e.g. changes in grain size distribution, organic matter content and elemental composition) with all these factors contributing for atypical 210Pb depth profiles. In addition, 137Cs, the chronostratigraphic marker most commonly used to corroborate 210Pb dating, fails to be preserved in the sedimentary record in tropical areas, owing to its solubility in marine waters, if at all detectable. The present study describes the challenges and proposed solutions for 210Pb dating saltmarsh sediment cores from two saltmarsh areas (southern Gulf of California and Yucatan Peninsula) including the use of plutonium isotopes for corroboration purposes. Acknowledgements: projects CONACYT CB2010/153492 and PDCPN201301/214349; UNAM PAPIIT-IN203313 and the PRODEP network "Aquatic contamination: levels and effects" (year 3).

  12. Impacts of flocculation on the distribution and diagenesis of iron in boreal estuarine sediments

    Directory of Open Access Journals (Sweden)

    T. Jilbert

    2018-03-01

    Full Text Available Iron (Fe plays a key role in sedimentary diagenetic processes in coastal systems, participating in various redox reactions and influencing the burial of organic carbon. Large amounts of Fe enter the marine environment from boreal river catchments associated with dissolved organic matter (DOM and as colloidal Fe oxyhydroxides, principally ferrihydrite. However, the fate of this Fe pool in estuarine sediments has not been extensively studied. Here we show that flocculation processes along a salinity gradient in an estuary of the northern Baltic Sea efficiently transfer Fe and OM from the dissolved phase into particulate material that accumulates in the sediments. Flocculation of Fe and OM is partially decoupled. This is likely due to the presence of discrete colloidal ferrihydrite in the freshwater Fe pool, which responds differently from DOM to estuarine mixing. Further decoupling of Fe from OM occurs during sedimentation. While we observe a clear decline with distance offshore in the proportion of terrestrial material in the sedimentary particulate organic matter (POM pool, the distribution of flocculated Fe in sediments is modulated by focusing effects. Labile Fe phases are most abundant at a deep site in the inner basin of the estuary, consistent with input from flocculation and subsequent focusing. The majority of the labile Fe pool is present as Fe (II, including both acid-volatile sulfur (AVS-bound Fe and unsulfidized phases. The ubiquitous presence of unsulfidized Fe (II throughout the sediment column suggests Fe (II-OM complexes derived from reduction of flocculated Fe (III-OM, while other Fe (II phases are likely derived from the reduction of flocculated ferrihydrite. Depth-integrated rates of Fe (II accumulation (AVS-Fe + unsulfidized Fe (II + pyrite for the period 1970–2015 are greater in the inner basin of the estuary with respect to a site further offshore, confirming higher rates of Fe reduction in near-shore areas

  13. Impacts of flocculation on the distribution and diagenesis of iron in boreal estuarine sediments

    Science.gov (United States)

    Jilbert, Tom; Asmala, Eero; Schröder, Christian; Tiihonen, Rosa; Myllykangas, Jukka-Pekka; Virtasalo, Joonas J.; Kotilainen, Aarno; Peltola, Pasi; Ekholm, Päivi; Hietanen, Susanna

    2018-03-01

    Iron (Fe) plays a key role in sedimentary diagenetic processes in coastal systems, participating in various redox reactions and influencing the burial of organic carbon. Large amounts of Fe enter the marine environment from boreal river catchments associated with dissolved organic matter (DOM) and as colloidal Fe oxyhydroxides, principally ferrihydrite. However, the fate of this Fe pool in estuarine sediments has not been extensively studied. Here we show that flocculation processes along a salinity gradient in an estuary of the northern Baltic Sea efficiently transfer Fe and OM from the dissolved phase into particulate material that accumulates in the sediments. Flocculation of Fe and OM is partially decoupled. This is likely due to the presence of discrete colloidal ferrihydrite in the freshwater Fe pool, which responds differently from DOM to estuarine mixing. Further decoupling of Fe from OM occurs during sedimentation. While we observe a clear decline with distance offshore in the proportion of terrestrial material in the sedimentary particulate organic matter (POM) pool, the distribution of flocculated Fe in sediments is modulated by focusing effects. Labile Fe phases are most abundant at a deep site in the inner basin of the estuary, consistent with input from flocculation and subsequent focusing. The majority of the labile Fe pool is present as Fe (II), including both acid-volatile sulfur (AVS)-bound Fe and unsulfidized phases. The ubiquitous presence of unsulfidized Fe (II) throughout the sediment column suggests Fe (II)-OM complexes derived from reduction of flocculated Fe (III)-OM, while other Fe (II) phases are likely derived from the reduction of flocculated ferrihydrite. Depth-integrated rates of Fe (II) accumulation (AVS-Fe + unsulfidized Fe (II) + pyrite) for the period 1970-2015 are greater in the inner basin of the estuary with respect to a site further offshore, confirming higher rates of Fe reduction in near-shore areas. Mössbauer 57Fe

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

    Science.gov (United States)

    Acosta-González, Alejandro; Marqués, Silvia

    2016-04-01

    Marine environments harbour a persistent microbial seed which can be shaped by changes of the environmental conditions such as contamination by petroleum components. Oil spills, together with small but continuous discharges of oil from transportation and recreational activities, are important sources of hydrocarbon pollution within the marine realm. Consequently, prokaryotic communities have become well pre-adapted toward oil pollution, and many microorganisms that are exposed to its presence develop an active degradative response. The natural attenuation of oil pollutants, as has been demonstrated in many sites, is modulated according to the intrinsic environmental properties such as the availability of terminal electron acceptors and elemental nutrients, together with the degree of pollution and the type of hydrocarbon fractions present. Whilst dynamics in the bacterial communities in the aerobic zones of coastal sediments are well characterized and the key players in hydrocarbon biodegradation have been identified, the subtidal ecology of the anaerobic community is still not well understood. However, current data suggest common patterns of response in these ecosystems. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Distribution of trace elements in the coastal sea sediments of Maslinica Bay, Croatia

    Science.gov (United States)

    Mikulic, Nenad; Orescanin, Visnja; Elez, Loris; Pavicic, Ljiljana; Pezelj, Durdica; Lovrencic, Ivanka; Lulic, Stipe

    2008-02-01

    Spatial distributions of trace elements in the coastal sea sediments and water of Maslinica Bay (Southern Adriatic), Croatia and possible changes in marine flora and foraminifera communities due to pollution were investigated. Macro, micro and trace elements’ distributions in five granulometric fractions were determined for each sediment sample. Bulk sediment samples were also subjected to leaching tests. Elemental concentrations in sediments, sediment extracts and seawater were measured by source excited energy dispersive X-ray fluorescence (EDXRF). Concentrations of the elements Cr, Cu, Zn, and Pb in bulk sediment samples taken in the Maslinica Bay were from 2.1 to over six times enriched when compared with the background level determined for coarse grained carbonate sediments. A low degree of trace elements leaching determined for bulk sediments pointed to strong bonding of trace elements to sediment mineral phases. The analyses of marine flora pointed to higher eutrophication, which disturbs the balance between communities and natural habitats.

  16. Perfluoroalkyl and polyfluoroalkyl substances in sediments from South Bohai coastal watersheds, China

    International Nuclear Information System (INIS)

    Zhu, Zhaoyun; Wang, Tieyu; Wang, Pei; Lu, Yonglong; Giesy, John P.

    2014-01-01

    Highlights: • Relatively high concentrations of PFAS, especially PFOA, were found in the Xiaoqing River sediment. • PFOA and PFBS were the dominant PFAS in the sediments from coastal and riverine area, respectively. • Concentrations of PFNA, PFDA and PFHxS in sediment were significantly correlated with concentrations of organic carbon. • Risks posed by PFOA and PFOS to benthic organisms from concentrations of PFAS in sediments were small. - Abstract: This study investigated the concentrations and distribution of Perfluoroalkyl and polyfluoroalkyl substances (PFAS) in sediments of 12 rivers from South Bohai coastal watersheds. The highest concentrations of ΣPFAS (31.920 ng g −1 dw) and PFOA (29.021 ng g −1 dw) were found in sediments from the Xiaoqing River, which was indicative of local point sources in this region. As for other rivers, concentrations of ΣPFAS ranged from 0.218 to 1.583 ng g −1 dw were found in the coastal sediments and from 0.167 to 1.953 ng g −1 dw in the riverine sediments. Predominant PFAS from coastal and riverine areas were PFOA and PFBS, with percentages of 30% and 35%, respectively. Partitioning analysis showed the concentrations of PFNA, PFDA and PFHxS were significantly correlated with organic carbon. The results of a preliminary environmental hazard assessment showed that PFOS posed the highest hazard in the Mi River, while PFOA posed a relative higher hazard in the Xiaoqing River

  17. Role of chemolithoautotrophic microorganisms involved in nitrogen and sulfur cycling in coastal marine sediments

    NARCIS (Netherlands)

    Lipsewers, Y.A.

    2017-01-01

    SummaryThe role of chemolithoautotrophic microorganisms has been considered to be of minor importancein coastal marine sediments although it has not been investigated in depth. Additionally,the impact of seasonal hypoxic/anoxic conditions on microbial chemolithoautotrophy in coastalmarine sediments

  18. Intercomparison of techniques for estimation of sedimentation rate in the Sabah and Sarawak coastal waters

    International Nuclear Information System (INIS)

    Zal U'yun Wan Mahmood; Zaharudin Ahmad; Abdul Kadir Ishak; Che Abd Rahim Mohamed

    2011-01-01

    A total of eight sediment cores with 50 cm length were taken in the Sabah and Sarawak coastal waters using a gravity corer in 2004 to estimate sedimentation rates using four mathematical models of CIC, Shukla-CIC, CRS and ADE. The average of sedimentation rate ranged from 0.24 to 0.48 cm year -1 , which is calculated based on the vertical profile of 210 Pbex in sediment core. The finding also showed that the sedimentation rates derived from four models were generally shown in good agreement with similar or comparable value at some stations. However, based on statistical analysis of paired sample t-test indicated that CIC model was the most accurate, reliable and suitable technique to determine the sedimentation rate in the coastal area. (author)

  19. A study of lead and cadmium speciation in some estuarine and coastal sediments

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, P.; Babu, P.V.R.; Sarma, V.V.

    ., Campbell, M., Weir, E., 2002, Identifying and managing adverse environmental health effects: 3. Lead exposure. CMAJ 166, 1287–1292. Stohs, S.J., Bagchi, D., 1995, Oxidative mechanisms in the toxicity of metal ions. Free Radical Biology and Medicine, 18... the kinetic speciation of Pb and Cd in the coastal and estuarine sediments of Bay of Bengal. Consider sediments samples of n different components, in which each component, M-Sediment i , exists in equilibrium with its dissociation products: the free metal...

  20. Heavy metals in marine coastal sediments: assessing sources, fluxes, history and trends.

    Science.gov (United States)

    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.

  1. Coastal sea-ice processes in Alaska and their relevance for sediment dynamics and coastal retreat (Invited)

    Science.gov (United States)

    Eicken, H.; Kapsch, M.; Johnson, M. A.; Weyapuk, W. U., Jr.

    2009-12-01

    Sea ice plays an important, complicated role in Arctic coastal sediment dynamics. It helps protect the shoreline from wave action and constrains coastal permafrost thaw; at the same time, sea ice is a highly effective sediment erosion and transport agent. For the coastline of (sub-)Arctic Alaska we have examined key processes that govern the role of sea ice as a geologic agent. Based on passive microwave satellite data for the time period 1979 to 2008 and augmented by field measurements and observations conducted by local sea-ice experts in coastal communities from 2006 onwards, we determined the onset of coastal ice spring break-up and fall freeze-up. These two events define the start and end of the open-water season during which the coast is rendered most vulnerable to thermal and dynamic processes promoting erosion. Satellite data show significant trends toward later fall freeze-up in many locations and moreover provide a picture of the statistical significance and variability of such trends in great spatio-temporal detail. Coastal ice observations suggest that important sea-ice processes (such as formation of ice berms) that precede freeze-up as detected by passive microwave data need to be taken into consideration in evaluating the vulnerability of the coastline and the specific threat of individual storms. Field observations, satellite data and local knowledge also highlight the substantial change in winter sea-ice regimes over the past two decades, with a much more mobile ice cover enhancing winter sediment transport. Ultimately, the shorter sea-ice season and the greater mobility and the lack of stability of winter coastal sea ice work in concert to increase the vulnerability of the coastline to erosion and flooding. At the same time, these changes provide a mechanism for effective redistribution and cross-shelf transport of sediments that prepares the stage for further erosive action in subsequent seasons.

  2. Effects of iron-ore mining and processing on metal bioavailability in a tropical coastal lagoon

    NARCIS (Netherlands)

    Pereira, A.A.; van Hattum, A.G.M.; Brouwer, A.; van Bodegom, P.M.; Rezende, C.E.; Salomons, W.

    2008-01-01

    In water systems, water quality and geochemical properties of sediments determine the speciation of trace metals, metal transport, and sediment-water exchange, influencing metal availability and its potential effects on biota. Studies from temperate climates have shown that iron-ore mining and

  3. Modelling of sediment transport at Muria peninsula coastal, Jepara

    International Nuclear Information System (INIS)

    Heni Susiati; Yarianto SBS; Wahyu Pandoe; Eko Kusratmoko; Aris Poniman

    2010-01-01

    Modelling of transport sediment modelling at Muria Peninsula have been done. In this study we had been used mathematical model that consist of hydrodynamics and sediment transport . Data input for modelling has been used tidal, monsoon wind, and river debit. Simulation result of sediment transport modelling showed that tides pattern and seasonal variations are the main causes of variations in the suspended sediment distribution in Muria Peninsula. (author)

  4. Coastal Engineering

    NARCIS (Netherlands)

    Van der Velden, E.T.J.M.

    1989-01-01

    Introduction, waves, sediment transport, littoral transport, lonshore sediment transport, onshore-offshore sediment transport, coastal changes, dune erosion and storm surges, sedimentation in channels and trenches, coastal engineering in practice.

  5. Observations of coastal sediment dynamics of the Tijuana Estuary Fine Sediment Fate and Transport Demonstration Project, Imperial Beach, California

    Science.gov (United States)

    Warrick, Jonathan A.; Rosenberger, Kurt J.; Lam, Angela; Ferreiera, Joanne; Miller, Ian M.; Rippy, Meg; Svejkovsky, Jan; Mustain, Neomi

    2012-01-01

    Coastal restoration and management must address the presence, use, and transportation of fine sediment, yet little information exists on the patterns and/or processes of fine-sediment transport and deposition for these systems. To fill this information gap, a number of State of California, Federal, and private industry partners developed the Tijuana Estuary Fine Sediment Fate and Transport Demonstration Project ("Demonstration Project") with the purpose of monitoring the transport, fate, and impacts of fine sediment from beach-sediment nourishments in 2008 and 2009 near the Tijuana River estuary, Imperial Beach, California. The primary purpose of the Demonstration Project was to collect and provide information about the directions, rates, and processes of fine-sediment transport along and across a California beach and nearshore setting. To achieve these goals, the U.S. Geological Survey monitored water, beach, and seafloor properties during the 2008–2009 Demonstration Project. The project utilized sediment with ~40 percent fine sediment by mass so that the dispersal and transport of fine sediment would be easily recognizable. The purpose of this report is to present and disseminate the data collected during the physical monitoring of the Demonstration Project. These data are available online at the links noted in the "Additional Digital Information" section. Synthesis of these data and results will be provided in subsequent publications.

  6. Distribution and origin sources of Polycyclic Aromatic Hydrocarbons (PAHs) pollution in sediment of Sarawak coastal area

    International Nuclear Information System (INIS)

    Mohd Shuhaimi Elias; Abdul Khalik Wood; Zaleha Hashim; Mohd Suhaimi Hamzah; Shamsiah Abdul Rahman; Nazaratul Ashifa Abdullah Salim

    2010-01-01

    Alkyl and parent Polycyclic Aromatic Hydrocarbons (PAHs) compounds in marine sediment sample collected from ten locations along Sarawak coastal areas were extracted and analyzed by using gas chromatography-mass spectrometry. The source identification of PAH pollution in marine sediment of Sarawak coastal areas were identify by ratios technique of An/ An+phen, Fl/ Fl +Py, B[a]A/ (B[a]A+Chry) and total Methyl Phen/ Phen. The total alkyl and parent PAHs concentration varies from 36.5 - 277.4 ng/ g dry weight (d.w.) with a mean concentration of 138.2 ng/ g d.w. The ratio values of PAHs pollution in marine sediment of Sarawak coastal areas are clearly indicating the PAHs pollutions are originated from petroleum (petrogenic) and petroleum combustion (pyrolytic). However, the origin sources of PAHs pollution in a few stations were uncertain due to mixing sources of PAHs. (author)

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

    DEFF Research Database (Denmark)

    Risgaard-Petersen, Nils; Nielsen, Lars Peter

    sulfide oxidation leads to electric field formation, sulfide depletion and acidification of the upper centimeters of the sediment. This promoted ion migration and dissolution of carbonates and iron sulfides. Sulfide released from iron sulfides was the major e-donor in the system. Ferrous iron released...... from iron sulfides was to a large extend deposited in the oxic zone as iron oxides and Ca2+ eventually precipitates at the surface as due to high pH caused by cathodic oxygen reduction. The result show how long distance electron transmission allows oxygen to drive the allocation of important minerals...... geochemical alterations in the upper centimetres of the anoxic sediment: Sulphides were oxidized to sulphate in anoxic sediment layers. Electrons from this half-reaction were passed to the oxic layers cm above. In this way the domain of oxygen was extended far beyond it’s physically presence. Bioelectrical...

  8. Effect of temperature and dispersant (COREXIT® EC 9500A) on aerobic biodegradation of benzene in a coastal salt marsh sediment.

    Science.gov (United States)

    Tao, Rui; Olivera-Irazabal, Miluska; Yu, Kewei

    2018-08-01

    The coastal ecosystem in the northern Gulf of Mexico (GoM) has been seriously impacted by the 2010 BP oil spill. Two experiments were conducted to study the effect of temperature and addition of the dispersant on biodegradation of benzene, as a representative of petroleum hydrocarbon, in a coastal salt marsh sediment under aerobic conditions. The results show that benzene biodegradation was approximately 6 time faster under aerobic conditions (Eh > +300 mV) than under anaerobic iron-reduction conditions (+14 mV  10 °C > 30 °C as expected in a saline environment. Application of the dispersant caused initial fluctuations of benzene vapor pressure during the incubation due to its hydrophobic and hydrophilic nature of the molecules. Presence of the dispersant shows an inhibitory effect on benzene biodegradation, and the inhibition increased with concentration of the dispersant. The Gulf coast sediment seems in a favorable scenario to recover from the BP oil spill with an average temperature around 20 °C in spring and fall season. Application of the dispersant may be necessary for the oil spill rescue operation, but its side effects may deserve further investigations. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    Sakellariadou, F.

    2012-04-01

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

  10. Evolution of radioactive dose rates in fresh sediment deposits along coastal rivers draining Fukushima contamination plume

    OpenAIRE

    Evrard, Olivier; Chartin, Caroline; Onda, Yuichi; Patin, Jeremy; Lepage, Hugo; Lef?vre, Ir?ne; Ayrault, Sophie; Ottl?, Catherine; Bont?, Philippe

    2013-01-01

    Measurement of radioactive dose rates in fine sediment that has recently deposited on channel bed-sand provides a solution to address the lack of continuous river monitoring in Fukushima Prefecture after Fukushima Dai-ichi nuclear power plant (FDNPP) accident. We show that coastal rivers of Eastern Fukushima Prefecture were rapidly supplied with sediment contaminated by radionuclides originating from inland mountain ranges, and that this contaminated material was partly exported by typhoons t...

  11. Characterization and evolution of the sediments of a Mediterranean coastal lagoon located next to a former mining area.

    Science.gov (United States)

    García, Gregorio; Muñoz-Vera, Ana

    2015-11-15

    Coastal lagoons are ecosystems that are relatively enclosed water bodies under the influence of both the terrestrial and the marine environment, being vulnerable to human impacts. Human activities, such as mining extraction, are significant anthropogenic coastal stressors that can negatively affect ecosystems and communities. In light of the above, the objective of this research is to examine the influence of metal mining activities on the composition of sediments of a Mediterranean coastal lagoon, named Mar Menor. This paper presents a comprehensive characterization for grain size, mineralogy, geochemistry and organic matter of sediments of this coastal lagoon, investigating their variation along space and time. Sedimentation dynamics are ruling clearly the grain size predominant in each area of the Mar Menor coastal lagoon, determining the existence of entrainment, transport and sedimentation areas. For minerals, elements and organic matter, sedimentation dynamics are also determining their distribution. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Structure and activity of lacustrine sediment bacteria involved in nutrient and iron cycles

    DEFF Research Database (Denmark)

    da Silva Martins, Gilberto Jorge; Terada, Akihiko; Ribeiro, Daniel C

    2011-01-01

    Knowledge of the bacterial community structure in sediments is essential to better design restoration strategies for eutrophied lakes. In this regard, the aim of this study was to quantify the abundance and activity of bacteria involved in nutrient and iron cycling in sediments from four Azorean...

  13. Spatial variability and the fate of cesium in coastal sediments near Fukushima, Japan

    Energy Technology Data Exchange (ETDEWEB)

    Black, E.E.; Buesseler, K.O. [Woods Hole Oceanographic Institution, Woods Hole, MA (United States)

    2014-07-01

    Quantifying the amount of cesium incorporated into marine sediments as a result of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident has proven challenging due to the limited multi-core sampling from within the 30 km zone around the facility; the inherent spatial heterogeneities in ocean sediments; and the potential for inventory fluctuations due to physical, biological, and chemical processes. Using {sup 210}Pb, {sup 234}Th, {sup 137}Cs, and {sup 134}Cs profiles from 20 sediment cores, coastal sediment inventories were reevaluated. A {sup 137}Cs sediment inventory of 100 ± 50 TBq was found for an area of 55 000 km{sup 2} using cores from this study and a total of 130 ± 60 TBq using an additional 181 samples. These inventories represent less than 1% of the estimated 15-30 PBq of cesium released during the FDNPP disaster. The time needed for surface sediment activities (0 to 3 cm) at the 20 locations to be reduced by 50% via sediment mixing was estimated to range from 0.4 to 26 yr. Due to the observed variability in mixing rates, grain size, and inventories, additional cores are needed to improve these estimates and capture the full extent of cesium penetration into the shallow coastal sediments, which was deeper than 14 cm for all cores retrieved from water depths less than 150 m.

  14. Investigations into the differential reactivity of endogenous and exogenous mercury species in coastal sediments.

    Science.gov (United States)

    Bouchet, S; Rodriguez-Gonzalez, P; Bridou, R; Monperrus, M; Tessier, E; Anschutz, P; Guyoneaud, R; Amouroux, D

    2013-03-01

    Stable isotopic tracer methodologies now allow the evaluation of the reactivity of the endogenous (ambient) and exogenous (added) Hg to further predict the potential effect of Hg inputs in ecosystems. The differential reactivity of endogenous and exogenous Hg was compared in superficial sediments collected in a coastal lagoon (Arcachon Bay) and in an estuary (Adour River) from the Bay of Biscay (SW France). All Hg species (gaseous, aqueous, and solid fraction) and ancillary data were measured during time course slurry experiments under variable redox conditions. The average endogenous methylation yield was higher in the estuarine (1.2 %) than in the lagoonal sediment (0.5 %), although both methylation and demethylation rates were higher in the lagoonal sediment in relation with a higher sulfate-reducing activity. Demethylation was overall more consistent than methylation in both sediments. The endogenous and exogenous Hg behaviors were always correlated but the exogenous inorganic Hg (IHg) partitioning into water was 2.0-4.3 times higher than the endogenous one. Its methylation was just slightly higher (1.4) in the estuarine sediment while the difference in the lagoonal sediment was much larger (3.6). The relative endogenous and exogenous methylation yields were not correlated to IHg partitioning, demonstrating that the bioavailable species distributions were different for the two IHg pools. In both sediments, the exogenous IHg partitioning equaled the endogenous one within a week, while its higher methylation lasted for months. Such results provide an original assessment approach to compare coastal sediment response to Hg inputs.

  15. Characterizing Feedbacks Between Environmental Forcing and Sediment Characteristics in Fluvial and Coastal Systems

    Science.gov (United States)

    Feehan, S.; Ruggiero, P.; Hempel, L. A.; Anderson, D. L.; Cohn, N.

    2016-12-01

    Characterizing Feedbacks Between Environmental Forcing and Sediment Characteristics in Fluvial and Coastal Systems American Geophysical Union, 2016 Fall Meeting: San Francisco, CA Authors: Scott Feehan, Peter Ruggiero, Laura Hempel, and Dylan Anderson Linking transport processes and sediment characteristics within different environments along the source to sink continuum provides critical insight into the dominant feedbacks between grain size distributions and morphological evolution. This research is focused on evaluating differences in sediment size distributions across both fluvial and coastal environments in the U.S. Pacific Northwest. The Cascades' high relief is characterized by diverse flow regimes with high peak/flashy flows and sub-threshold flows occurring in relative proximity and one of the most energetic wave climates in the world. Combining analyses of both fluvial and coastal environments provides a broader understanding of the dominant forces driving differences between each system's grain size distributions, sediment transport processes, and resultant evolution. We consider sediment samples taken during a large-scale flume experiment that simulated floods representative of both high/flashy peak flows analogous to runoff dominated rivers and sub-threshold flows, analogous to spring-fed rivers. High discharge flows resulted in narrower grain size distributions while low flows where less skewed. Relative sediment size showed clear dependence on distance from source and the environments' dominant fluid motion. Grain size distributions and sediment transport rates were also quantified in both wave dominated nearshore and aeolian dominated backshore portions of Long Beach Peninsula, Washington during SEDEX2, the Sandbar-aEolian-Dune EXchange Experiment of summer 2016. The distributions showed spatial patterns in mean grain size, skewness, and kurtosis dependent on the dominant sediment transport process. The feedback between these grain size

  16. Sediment grain size and hydrodynamics in Mediterranean coastal ...

    Indian Academy of Sciences (India)

    Integrated classification maps were produced by combining sediment grain-size and hydrological data .... Integrated classification of abiotic parameters in lagoons. 1099. Figure 1. ...... spline with tension: I. Theory and implementation; Math.

  17. Experimental studies on the geochemical behaviour of 54-Mn considering coastal and deep sea sediments

    International Nuclear Information System (INIS)

    Guegueniat, P.; Boust, D.; Aprosi, G.

    1986-01-01

    In order to study the geochemical behaviour of 54-Mn in the marine environment (Mn 2+ ) 200 sediments gathered in deep sea and in coastal waters were contaminated experimentally. To correlate the various results, the oxidation processes occuring with or without sediments should be specified. Without sediments, in 'blanks', the deposition rate of 54-Mn on the walls brings into play oxidation developing approximately according to a single order linear function. Consequently, it is characterized by a half-life (time for half 54-Mn to be retained) very similar to a residence time (Tsub(R)). In our water samples, Tsub(R) ranged from 12 to 150 days. (author)

  18. Potential nitrate removal in a coastal freshwater sediment (Haringvliet Lake, The Netherlands) and response to salinization

    NARCIS (Netherlands)

    Laverman, A.M.; Canavan, R.W.; Slomp, C.P.; Van Cappellen, P.

    2007-01-01

    Nitrogen transformations and their response to salinization were studied in bottom sediment of a coastal freshwater lake (Haringvliet Lake, The Netherlands). The lake was formed as the result of a river impoundment along the south-western coast of the Netherlands, and is currently targeted for

  19. Assessing effects of changing land use practices on sediment loads in Panther Creek, north coastal California

    Science.gov (United States)

    Mary Ann Madej; Greg Bundros; Randy Klein

    2012-01-01

    Revisions to the California Forest Practice Rules since 1974 were intended to increase protection of water quality in streams draining timber harvest areas. The effects of improved timber harvesting methods and road designs on sediment loading are assessed for the Panther Creek basin, a 15.4 km2 watershed in Humboldt County, north coastal...

  20. SEDIMENT CHEMICAL CONTAMINATION AND TOXICITY ASSOCIATED WITH A COASTAL GOLF COURSE COMPLEX.

    Science.gov (United States)

    The increasing density of golf courses represents a potential source of sediment contamination to nearby coastal areas, the chemical and biological magnitude of which is almost unknown. The objective of this study was to determine the concentrations of contaminants and toxicities...

  1. Late Quaternary faunal change in coastal Arabian sea sediments

    Digital Repository Service at National Institute of Oceanography (India)

    Borole, D.V.; Rao, K.K; Krishnamurthy, R.V.; Somayajulu, B.L.K

    Carbonate content and faunal composition of two gravity cores from the coastal Arabian Sea provide evidence of a major environmental change in surface ocean waters about 13,000 yr B.P. Radiocarbon dating indicates that deposition rates ranged from 1...

  2. Modified finite element transport model, FETRA, for sediment and radionuclide migration in open coastal waters

    International Nuclear Information System (INIS)

    Onishi, Y.; Arnold, E.M.; Mayer, D.W.

    1979-08-01

    The finite element model, FETRA, simulates transport of sediment and radionuclides (and other contaminants, such as heavy metals, pesticides, and other toxic substances) in surface water bodies. The model is an unsteady, two-dimensional (longitudinal and lateral) model which consists of the following three submodels coupled to include sediment-contaminant interactions: (1) sediment transport submodel, (2) dissolved contaminant transport submodel, and (3) particulate contaminant (contaminant adsorbed by sediment) transport submodel. Under the current phase of the study, FETRA was modified to include sediment-wave interaction in order to extend the applicability of the model to coastal zones and large lakes (e.g., the Great Lakes) where wave actions can be one of the dominant mechanisms to transport sediment and toxic contaminant. FETRA was further modified to handle both linear and quadratic approximations to velocity and depth distributions in order to be compatible with various finite element hydrodynamic models (e.g., RMA II and CAFE) which supply hydrodynamic input data to FETRA. The next step is to apply FETRA to coastal zones to simulate transport of sediment and radionuclides with their interactions in order to test and verify the model under marine and large lacustrine environments

  3. 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

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, Anisa, E-mail: coppering@ymail.com; Hamzah, Zaini; Wood, Ab. Khalik [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450, Shah Alam, Selangor (Malaysia); Saat, Ahmad [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450, Shah Alam, Selangor (Malaysia); Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia)

    2016-01-22

    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 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 (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})

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

    Science.gov (United States)

    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).

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

    International Nuclear Information System (INIS)

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

    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 ( 232 Th, 238 U and 40 K) 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 (I 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 ex )

  6. Removal of iron and manganese from groundwater: a study of using potassium permanganate and sedimentation

    Directory of Open Access Journals (Sweden)

    Elsheikh Mohamed

    2018-01-01

    Full Text Available Experiments are done for different combinations of Fe+2 and Mn+2 concentrations. The obtained results show that Potassium Permanganate (PP gives good results in iron and manganese removal. By using PP dose near to half of the theoretically required one, it can remove up to 100 % and 90 % of iron and manganese, respectively over different tested concentrations at pH=7.0. Increasing rate of filtration influences the Mn+2 removal process obviously. Sedimentation is required when combined concentrations of iron and manganese are greater than 5.0 ppm to reduce filter rapid clogging. Using conventional treatment with adding alum, flocculation, sedimentation and filtration can remove up to 97% and 18% of iron and manganese, respectively. Using PP in addition to alum enhances manganese removal but decreases iron removal. However, using alum with increasing pH to 10 leads to 100 % and 95 % of Fe+2 and Mn+2 removal and increases filter working period.

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

    Science.gov (United States)

    Kamalakannan, K; Balakrishnan, S; Sampathkumar, P

    2017-04-15

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

  8. Amino acid biogeo- and stereochemistry in coastal Chilean sediments

    DEFF Research Database (Denmark)

    Lomstein, Bente Aagaard; Jørgensen, Bo Barker; Schubert, Carsten J.

    2006-01-01

    The spatial distribution of total hydrolysable amino acids (THAA) and amino acid enantiomers (D- and L-forms) was investigated in sediments underlying two contrasting Chilean upwelling regions,: at ~23°S off Antofagasta and at ~36°S off Concepcion. The contribution of amino acids to total organic...... carbon (%TAAC: 7-14%) and total nitrogen (%TAAN: 23-38%) in surface sediments decreased with increasing water depth (from 126 to 1350 m) indicating that organic matter becomes increasingly decomposed in surface sediments at greater water depth. Changes in the ratio between the protein amino acid...... aspartate and its non-protein degradation product β-alanine confirmed this observation. Furthermore, estimates of THAA mineralization showed that sedimentary amino acid reactivity decreased with both increasing water depth as well as progressive degradation status of the organic matter that was incorporated...

  9. Magnitude and variability of methane production and concentration in tropical coastal lagoons sediments

    Directory of Open Access Journals (Sweden)

    Antonella Petruzzella

    Full Text Available AIM: Coastal wetlands are potential zones for methane (CH4 production. The present study aims to evaluate the spatial variation of CH4 production and concentration in ten tropical coastal lagoons, the influence of aquatic macrophytes on the sediment CH4 concentration and how the magnitude of these potential CH4 production rates compare to those in other ecosystems. METHODS: Sediments were sampled in ten coastal lagoons, with one site in the limnetic region and another site in aquatic macrophyte stands when they were present in the littoral region. We measured the CH4 production as a potential rate, and CH4 concentration was directly measured from sediment samples. RESULTS: The highest potential CH4 production (PMP rates were found in alkaline and hypersaline lagoons. However, Cabiúnas, which is a freshwater lagoon densely colonized by aquatic macrophytes, also exhibited a high PMP rate. We also observed that the sediment CH4 concentration in the littoral region was higher than in the limnetic region in all of the investigated lagoons except Paulista, which presented the opposite pattern. The PMP rates observed in the studied lagoons were low compared to other aquatic ecosystems. CONCLUSION: Our results suggest that the sediments of saline lagoons are important CH4 production sites, and in general, aquatic macrophytes have a positive influence on methanogenesis, which was evident based on the CH4 concentrations present in the sediments of these lagoons. Further studies should focus on the processes underlying the CH4 patterns observed in the tropical coastal lagoons, especially concerning the coupling between CH4 production and concentration.

  10. Linking the historic 2011 Mississippi River flood to coastal wetland sedimentation

    Science.gov (United States)

    Falcini, Federico; Khan, Nicole S.; Macelloni, Leonardo; Horton, Benjamin P.; Lutken, Carol B.; McKee, Karen L.; Santoleri, Rosalia; Colella, Simone; Li, Chunyan; Volpe, Gianluca; D’Emidio, Marco; Salusti, Alessandro; Jerolmack, Douglas J.

    2012-01-01

    Wetlands in the Mississippi River deltaic plain are deteriorating in part because levees and control structures starve them of sediment. In Spring of 2011 a record-breaking flood brought discharge on the lower Mississippi River to dangerous levels, forcing managers to divert up to 3500 m3/s-1 of water to the Atchafalaya River Basin. Here we quantify differences between the Mississippi and Atchafalaya River inundation and sediment-plume patterns using field-calibrated satellite data, and assess the impact these outflows had on wetland sedimentation. We characterize hydrodynamics and suspended sediment patterns of the Mississippi River plume using in-situ data collected during the historic flood. We show that the focused, high-momentum jet from the leveed Mississippi delivered sediment far offshore. In contrast, the plume from the Atchafalaya was more diffuse; diverted water inundated a large area; and sediment was trapped within the coastal current. Maximum sedimentation (up to several centimetres) occurred in the Atchafalaya Basin despite the larger sediment load carried by the Mississippi. Minimum accumulation occurred along the shoreline between these river sources. Our findings provide a mechanistic link between river-mouth dynamics and wetland sedimentation patterns that is relevant for plans to restore deltaic wetlands using artificial diversions.

  11. Sediment budget variation at watershed scale due to anthropogenic pressures, and its relationship to coastal erosion

    Science.gov (United States)

    Aiello, Antonello; Adamo, Maria; Canora, Filomena

    2014-05-01

    The transfer of sediments from hydrographic basins towards the coast is a significant pathway of material transfer on Earth. In sedimentary environment, the main portion of sediment that enters the coastal areas is derived originally from erosion in the coastal watersheds. Extensive anthropogenic pressures carried out within coastal basins have long shown negative impacts on littoral environments. In fluvial systems, sediments trapped behind dams and in-stream gravel mining cause the reduction in sediment supply to the coast. Along the Jonian littoral of the Basilicata Region (southern Italy), natural coastal processes have been severely disrupted since the second half of the 20th century as a result of riverbed sand and gravel mining and dam construction, when economic advantages were measured in terms of the development of infrastructure, water storage, and hydropower production for the agricultural, industrial and socio-economic development of the area. Particularly, the large numbers of dams and impoundments that have been built in the hydrographic basins have led a signi?cant reduction on river sediment loads. As a result, the Jonian littoral is experiencing a catalysed erosion phenomenon. In order to increase understanding of the morpho-dynamics of the Jonian littoral environment and more fully appreciate the amount of coastal erosion, an evaluation of the sediment budget change due to dam construction within the hydrographic basins of the Basilicata Region needs to be explored. Since quantitative data on decadal trends in river sediment supply before and after dam construction are lacking, as well as updated dam silting values, river basin assessment of the spatial patterns and estimated amount of sediment erosion and deposition are important in evaluating changes in the sediment budget. As coastal areas are being affected by an increasing number of population and socio-economic activities, the amount of sediment deficit at the littoral can permit to

  12. Temporal deconvolution of vascular plant signatures delivered to coastal sediments

    Science.gov (United States)

    Vonk, J.; Drenzek, N. J.; Hughen, K. A.; Stanley, R.; Montluçon, D. B.; McIntyre, C.; Southon, J. R.; Santos, G.; Andersson, A.; Sköld, M.; Eglinton, T. I.

    2017-12-01

    Presently, relatively little is known about the amount of time that lapses between the photosynthetic fixation of carbon by vascular land plants and its incorporation into the marine sedimentary record. It is clear that there are multiple potential intermediate storage pools and transport trajectories that vascular plant carbon may experience, and the age of vascular plant carbon accumulating in marine sediments will reflect these different pre-depositional histories. Here we use molecular-level radiocarbon (14C) analysis to develop down-core 14C profiles for higher plant leaf wax-derived fatty acids isolated from sediments from three sites across a 60-degrees latitudinal gradient (Cariaco Basin, Saanich Inlet, and Mackenzie Delta). The sediment profiles were used as a direct measure of the storage and transport times experienced by these biomolecular tracer compounds. Residence times are evaluated by comparing these records to the 14C history of atmospheric CO2. Using a modeling framework, we conclude that there is, in addition to a variable "young" pool, a millennial pool of compounds that consists of 49-78 % of the fractional contribution of organic carbon (OC) that exhibits variable ages for the different depositional settings. For the Mackenzie Delta sediments, we find a mean age of the millennial pool of 28 ky, suggesting pre-aging in permafrost soils, whereas the millennial pool in Saanich Inlet and Cariaco Basin sediments is younger with 7.9 and 2.4-3.2 ky, respectively, suggesting limited storage in terrestrial reservoirs. The "young" pool, conditionally defined as vascular plant C in deltaic and marine settings undergoes pre-aging in terrestrial reservoirs. The age distribution, reflecting storage and transport times, depends on landscape-specific factors such as local topography, hydrographic characteristics, and degree of soil build-up and preservation.

  13. Are styrene oligomers in coastal sediments of an industrial area aryl hydrocarbon-receptor agonists?

    Science.gov (United States)

    Hong, Seongjin; Lee, Junghyun; Lee, Changkeun; Yoon, Seo Joon; Jeon, Seungyeon; Kwon, Bong-Oh; Lee, Jong-Hyeon; Giesy, John P; Khim, Jong Seong

    2016-06-01

    Effect-directed analysis (EDA) was performed to identify the major aryl hydrocarbon receptor (AhR) agonists in sediments collected from a highly industrialized area (Lake Shihwa, Korea). Great AhR-mediated potencies were found in fractions containing aromatic compounds with log Kow values of 5-8, and relatively great concentrations of styrene oligomers (SOs) and polycyclic aromatic hydrocarbons (PAHs) were detected in those fractions. Until now, there was little information on occurrences and toxic relative potencies (RePs) of SOs in coastal environments. In the present study; i) distributions and compositions, ii) AhR binding affinities, and iii) contributions of SOs to total AhR-mediated potencies were determined in coastal sediments. Elevated concentrations of 10 SOs were detected in sediments of inland creeks ranging from 61 to 740 ng g(-1) dry mass (dm), while lesser concentrations were found in inner (mean = 33 ng g(-1) dm) and outer regions (mean = 25 ng g(-1) dm) of the lake. Concentrations of PAHs in sediments were comparable to those of SOs. 2,4-diphenyl-1-butene (SD3) was the predominant SO analogue in sediments. SOs and PAHs were accumulated in sediments near sources, and could not be transported to remote regions due to their hydrophobicity. RePs of 3 SOs could be derived, which were 1000- to 10,000-fold less than that of one representative potent AhR active PAH, benzo[a]pyrene. Although concentrations of SOs in sediments were comparable to those of PAHs, the collective contribution of SOs to total AhR-mediated potencies were rather small (coastal environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. [Distribution of polycyclic aromatic hydrocarbons in water and sediment from Zhoushan coastal area, China].

    Science.gov (United States)

    Jiang, Min; Tuan, Le Huy; Mei, Wei-Ping; Ruan, Hui-Hui; Wu, Hao

    2014-07-01

    The spatial and temporal distribution of 16 polycyclic aromatic hydrocarbons (PAHs) has been investigated in water and sediments of Zhoushan coastal area every two months in 2012. The concentrations of total PAHs ranged from 382.3 to 816.9 ng x L(-1), with the mean value of 552.5 ng x L(-1) in water; whereas it ranged from 1017.9 to 3047.1 ng x g(-1), with the mean value of 2 022.4 ng x g(-1) in sediment. Spatial distribution showed that Yangshan and Yanwoshan offshore area had the maximum and minimum of total PAHs contents in water, while the maximum and minimum occurred at Yangshan and Zhujiajian Nansha offshore area in sediment. Temporal distribution revealed that total PAHs contents in water reached the maximum and minimum values in October and June, however in sediments these values were found in August and June, respectively. The PAHs pollution was affected by oil emission, charcoal and coal combustion. Using the biological threshold and exceeded coefficient method to assess the ecological risk of PAHs in Zhoushan coastal area, the result showed that sigma PAHs had a lower probability of potential risk, while there was a higher probability of potential risk for acenaphthylene monomer, and there might be ecological risk for acenaphthene and fluorene. Distribution of PAHs between sediment and water showed that Zhoushan coastal sediment enriched a lot of PAHs, meanwhile the enrichment coefficient (K(d) value) of sediment in Daishan island was larger than that in Zhoushan main island.

  15. Design of a semi-autonomous boat for measurements of coastal sedimentation and erosion

    Directory of Open Access Journals (Sweden)

    D. Smith

    2015-03-01

    Full Text Available Measurement of sediment deposition and erosion in coastal areas is a challenge due to soft shifting sediments, but is critical to assessing loss or restoration of coastal sediments and wetlands. The aim of this project was to design and construct a semi-autonomous boat with water depth measuring capabilities. It was intended to map the depth of coastal wetlands to determine erosion rates and assess coastal restoration effects. Depth-measuring equipment was incorporated into an autonomous pontoon boat powered by solar panels. The propulsion system consisted of two paddlewheels and two-way motors to allow movement and positioning for measurements. Modifications included a lightweight, hard coating on the pontoons and powder-coating the frame to extend their usable life. A microcontroller controlled the boat and captured depth data from sensors and location data with a GPS system. The depth measuring system consisted of a pulley and counter system that completed each measurement in less than 45 seconds. This allowed the boat to take approximately 400 measurements per day. Net accuracy was approximately 3 cm in the tested configuration. The boat can continually measure the depth of specified areas in the wetlands; with this data, the change in depth can be monitored to see the effects of restoration projects.

  16. Activities concentration of 239+240Pu in sediment in Sabah and Sarawak coastal area

    International Nuclear Information System (INIS)

    Jalal Sharib; Zaharudin Ahmad; Yii Mei Wo; Ahmad Sanadi Abu Bakar; Norfaizal Mohamed; Kamarozaman Ishak; Zulkifli Daud

    2008-08-01

    The determination of plutonium, 239+240 Pu activity concentration and their distributions along the coastal area of the Sabah and Sarawak have been performed using alpha spectrometry counting system. The sampling coastal sediment for this study was carried out in July 2004 as part of the Marine Radioactivity Database Development Project for Malaysia. This results show that the distribution of Plutonium, 239+240 Pu radionuclides in coastal sediment is consistent, their activities are depending on the sampling locations. Generally, the 239+240 Pu activities measured in Sabah and Sarawak coastal sediment are in the range of BDL - 1.83 Bq/kg and 0.11 - 0.841 Bq/kg dry weights, respectively. The sampling stations, Persisiran Lubok Sabanan, SB 15 and Sungai Similajau, SR 13 showed the highest plutonium, 239+240 Pu radionuclides isotopes activity in Sabah and Sarawak. Meanwhile, these two stations shows higher activity compare to West Coast of Peninsular of Malaysia station for the Marine Radioactivity Database Development Project for Malaysia. (Author)

  17. Settling characteristics of fine-grained sediments used in Louisiana coastal land building and restoration projects

    Science.gov (United States)

    Ghose Hajra, M.

    2016-02-01

    Coastal property development, sea level rise, geologic subsidence, loss of barrier islands, increasing number and intensity of coastal storms and other factors have resulted in water quality degradation, wetlands loss, reduced storm and surge protection, ground settlement, and other challenges in coastal areas throughout the world. One of the goals towards reestablishing a healthy coastal ecosystem is to rebuild wetlands with river diversion or sediment conveyance projects that optimally manage and allocate sediments, minimally impact native flora and fauna, and positively affect the water quality. Engineering properties and material characteristics of the dredged material and foundation soils are input parameters in several mathematical models used to predict the long term behavior of the dredged material and foundation soil. Therefore, proper characterization of the dredged material and foundation soils is of utmost importance in the correct design of a coastal restoration and land reclamation project. The sedimentation and consolidation characteristics of the dredged material as well as their effects on the time rate of settlement of the suspended solid particles and underlying foundation soil depend, among other factors, on the (a) grain size distribution of the dredged material, (b) salinity (fresh, brackish, or saltwater environment) of the composite slurry, and (c) concentration of the solid particles in the slurry. This paper will present the results from column settling tests and self-weight consolidation tests performed on dredged samples obtained from actual restoration projects in Louisiana. The effects of salinity, grain size distribution, and initial particle concentration on the sedimentation and consolidation parameters of the dredged material will also be discussed.

  18. Dominance of sulfur-fueled iron oxide reduction in low-sulfate freshwater sediments.

    Science.gov (United States)

    Hansel, Colleen M; Lentini, Chris J; Tang, Yuanzhi; Johnston, David T; Wankel, Scott D; Jardine, Philip M

    2015-11-01

    A central tenant in microbial biogeochemistry is that microbial metabolisms follow a predictable sequence of terminal electron acceptors based on the energetic yield for the reaction. It is thereby oftentimes assumed that microbial respiration of ferric iron outcompetes sulfate in all but high-sulfate systems, and thus sulfide has little influence on freshwater or terrestrial iron cycling. Observations of sulfate reduction in low-sulfate environments have been attributed to the presumed presence of highly crystalline iron oxides allowing sulfate reduction to be more energetically favored. Here we identified the iron-reducing processes under low-sulfate conditions within columns containing freshwater sediments amended with structurally diverse iron oxides and fermentation products that fuel anaerobic respiration. We show that despite low sulfate concentrations and regardless of iron oxide substrate (ferrihydrite, Al-ferrihydrite, goethite, hematite), sulfidization was a dominant pathway in iron reduction. This process was mediated by (re)cycling of sulfur upon reaction of sulfide and iron oxides to support continued sulfur-based respiration--a cryptic sulfur cycle involving generation and consumption of sulfur intermediates. Although canonical iron respiration was not observed in the sediments amended with the more crystalline iron oxides, iron respiration did become dominant in the presence of ferrihydrite once sulfate was consumed. Thus, despite more favorable energetics, ferrihydrite reduction did not precede sulfate reduction and instead an inverse redox zonation was observed. These findings indicate that sulfur (re)cycling is a dominant force in iron cycling even in low-sulfate systems and in a manner difficult to predict using the classical thermodynamic ladder.

  19. Polychlorinated biphenyls and pesticides in surficial coastal sediments of the Ligurian Sea

    Energy Technology Data Exchange (ETDEWEB)

    Bertolotto, R.M.; Cuneo, C.; Albanese, S. [ARPAL, Direzione Scientifica, Genova (Italy); Magherini, A. [ARPAL, Dipartimento di Genova, Genova (Italy); Frignani, M.; Bellucci, L.G.; Alvarado-Aguilar, D. [ISMAR, Sezione di Geologia Marina, Bologna (Italy)

    2004-09-15

    Polychlorinated biphenyls (PCBs) and chlorinated pesticides, such as DDT and its analogues, are organic contaminants widespread throughout the terrestrial and oceanic environments due to their common use and their resistance to degradation. Since harmful effects have been associated to these chemicals and well documented, they are classified as priority pollutants by both the US Environmental Protection Agency (EPA) and the European Union. Because of the very low solubility in water and the tendency to adsorb onto sediment particles, the ultimate fate of both PCBs and DDTs in the marine environment is the incorporation into sediments. Hence, the concentrations of these chlorinate chemicals in bottom sediments can provide an insight on the quality of the environment and the potential threat to marine organisms and human beings. The Ligurian Sea belongs to the north part of the western Mediterranean. The coastal morphology of the Liguria Region is rather variable, and frequently cliffs drop sheer to the sea. The limited width of the coastal zone, comprised between the sea and the mountains, determined a gathering of the urban areas with a consequent concentration of both civil and industrial presence in a narrow but highly populated territory. In particular Genova, but also other cities have a long history of industrial and harbour activities, whereas long tracts of the coast are dedicated to tourism. The circulation of the Ligurian Sea is rather well known. In particular, surface and intermediate currents follow a cyclonic circulation. However local circulation is the true responsible of the dispersion of sediment material along the coast, and these alongshore currents often cause an eastward oriented transport. The Ligurian coastal zone is very developed, and hosts all sort of industrial, agricultural and tourist activities that can be sources of persistent organochlorine chemicals. Therefore, the purpose of this study was to assess concentrations, distributions

  20. Coastal change from a massive sediment input: Dam removal, Elwha River, Washington, USA

    Science.gov (United States)

    Warrick, Jonathan A.; Gelfenbaum, Guy R.; Stevens, Andrew; Miller, Ian M.; Kaminsky, George M.; Foley, Melissa M.

    2015-01-01

    The removal of two large dams on the Elwha River, Washington, provides an ideal opportunity to study coastal morphodynamics during increased sediment supply. The dam removal project exposed ~21 million cubic meters (~30 million tonnes) of sediment in the former reservoirs, and this sediment was allowed to erode by natural river processes. Elevated rates of sand and gravel sediment transport in the river occurred during dam removal. Most of the sediment was transported to the coast, and this renewed sediment supply resulted in hundreds of meters of seaward expansion of the river delta since 2011. Our most recent survey in January 2015 revealed that a cumulative ~3.5 million m3 of sediment deposition occurred at the delta since the beginning of the dam removal project, and that aggradation had exceeded 8 m near the river mouth. Some of the newly deposited sediment has been shaped by waves and currents into a series of subaerial berms that appear to move shoreward with time.

  1. Organic carbon isotope ratios of recent sediments from coastal lagoons of the Gulf of Mexico, Mexico

    International Nuclear Information System (INIS)

    Botello, A.V.; Mandelli, E.F.; Macko, S.; Parker, P.L.

    1980-01-01

    The stable carbon isotope composition of sedimentary organic carbon was determined in the sediments of seven coastal lagoons of the Gulf of Mexico, Mexico. For most of the lagoons the delta 13 C values for sediments ranged from -20.1 to -23.9 parts per thousand. Anomalously low values, -26.8 to 29.3 parts per thousand were determined in sediments of two of the studied lagoons, probably due to the presence of organic carbon from anthropogenic sources, naturally absent in these environments. The delta 13 C values determined in the tissues of oysters collected at the same time in the different lagoons were very similar to those recorded in the sediments. (author)

  2. Effects of dredged sediment disposal on the coastal marine macrobenthic assemblage in Southern Brazil

    Directory of Open Access Journals (Sweden)

    L. G. Angonesi

    Full Text Available The aim of this study was to evaluate the deposition impact of dredged material from Patos lagoon estuary on a benthic macroinvertebrate assemblage structure in an adjacent coastal marine area. Nine sampling stations were chosen at random in the disposal area, and nine others in the same way in an adjacent control area. Samples were collected at a 19 m depth before sediment disposal (11 July 2000, during dredging and disposal operations (25 Oct. 2000, and three months thereafter (24 Aug. 2001. Statistical analysis indicated that sampling periods presented similar characteristics in both the control and disposal sites. Disposal of dredged sediment from Patos lagoon had no detectable detrimental effects upon macrobenthic faunal assemblage at the dumping site. This result is attributed both to adaptation of resident biota to dynamic sedimentary conditions and to the fine estuarine sediment dredged, the dispersion of which in the water column might have minimized sediment deposition and consequent damage to the benthic fauna.

  3. Polycyclic aromatic hydrocarbon contamination in stormwater detention pond sediments in coastal South Carolina.

    Science.gov (United States)

    Weinstein, John E; Crawford, Kevin D; Garner, Thomas R

    2010-03-01

    The purpose of this study was to characterize the polycyclic aromatic hydrocarbon (PAH) contamination in the sediments of stormwater detention ponds in coastal South Carolina. Levels of the sum of PAH analytes were significantly higher in the sediments of commercial ponds compared to that of reference, golf course, low-density residential, and high-density residential ponds. Isomer ratio analysis suggested that the predominant source of PAHs were pyrogenic; however, many ponds had a PAH signature consistent with mixed uncombusted and combusted PAH sources. PAH levels in these sediments could be modeled using both pond drainage area and pond surface area. These results demonstrate that the sediment from most commercial ponds, and a few residential and golf course ponds, were moderately contaminated with PAHs. PAH levels in these contaminated ponds exceeded between 42% and 75% of the ecological screening values for individual PAH analytes established by US EPA Region IV, suggesting that they may pose a toxicological risk to wildlife.

  4. Manganese and iron as oxygen carriers to anoxie estuarine sediment

    Science.gov (United States)

    Brayner, F. M. M.; Matvienko, B.

    2003-05-01

    We studied the concentration of a series of transition metals including Mn and Fe in an estuarine fishpond. The pond is situated at latitude 8°10'S and longitude 34°55'W, in the Capibaribe River estuary, within the Recife city boundaries, which is located in Pernambuco, a state of the Brazilian Northeast Pond area is 1.5 ha and it bas a 0.5 m depth. It is separated from the river by dikes. Water temperature at 28° C is stable throughout the year. Light breezes keep the water aerated, but intense ongoing decomposition makes the sediment anoxie. The area, originally of mangrove type, has been changed by antropic action on its fauna and vegetation. The study focuses on changes in behaviour of heavy metals. Samples of bottom sediments wore collected by Eckman dredge sediment sampler and total metal concentration was determined by the lithium borate fusion method. Water, recent sediment, and consolidated sediment were examined in this fishpond where Mn and Fe are brought in periodically by water and then gradually go into the sediment at respective rates of 10.52 and 1332 mg m^{-2}a^{-1}. Strong bioturbation re-suspends sediment while simultaneously re-dissolution of these ions is going on fhrough reduction in the anoxie sédiment. As soluble species these ions migrate from sediment to water and are there continually oxidized by dissolved oxygen, becoming insoluble. With their precipitation, chemically bound oxygen is carried down to the sediment, constituting a parallel channel of transport in addition to migration into the sediment bydiffusion of the oxygen dissolved in the water. The estimated flow rates are 3.25 and 76 mg O2 m^{-2}a^{-1} due to Mn and Fe respectively. The rates were established using natural silicon as a tracer.

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

    Science.gov (United States)

    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).

  6. Assessment of metals pollution in sediment cores from the Sabah-Sarawak coastal waters

    International Nuclear Information System (INIS)

    Zal Uyun Wan Mahmood; Zaharudin Ahmad; Che Abdul Rahim Mohamed; Abdul Kadir Ishak; Norfaizal Mohammed

    2011-01-01

    The distribution, enrichment and pollution status of metals in sediment cores from the Sabah-Sarawak coastal waters were studied. Seven sediment cores were taken in July 2004 using a gravity box corer. The metals of Cu, Zn and Pb were analyzed by ICP-MS to assess the pollution status of the sediments. The sediment fine fraction and organic carbon content was also analyzed. Enrichment Factor (EF), Geo accumulation Index (Igeo) and Pollution Load Index (PLI) was calculated as criteria of possible contamination. The results showed that collected sediments were composed with clay, silt and sand as 12 - 74 %, 27 - 72 % and 0 - 20 %, respectively. Meanwhile, organic carbon contents were relatively low and constant over time, based on sediment depth profiles, and it did not exceed 5 % at any sampling station. The average metal concentrations in sediment cores at all sampling station were distributed in the ranges of 1.66 ± 1.36 - 6.61 ± 0.12 μgg -1 for Cu, 26.55 ± 1.04 - 57.94 ± 1.58 μgg -1 for Zn and 3.99 ± 0.10 - 14.48 ± 0.32 μgg -1 for Pb. According to calculations of EF, I geo and PLI, it can be concluded that concentrations of Cu, Zn and Pb were not significantly affected by pollution from anthropogenic sources at the seven sampling locations. Thus, the metal content of Cu, Zn and Pb in sediment should not cause pollution problem to the marine environment of Sabah-Sarawak coastal waters and further response measures are not needed. (author)

  7. The Importance of Microbial Iron Sulfide Oxidation for Nitrate Depletion in Anoxic Danish Sediments

    DEFF Research Database (Denmark)

    Vaclavkova, Sarka; Jacobsen, Ole Stig; Jørgensen, Christian Juncher

    2014-01-01

    of organic carbon in the sediment. An apparent salinity limitation to MISON was observed in the most brackish environment. Addition of high surface area synthetically precipitated iron sulfide (FeS x ) to the aquifer sediment with the lowest natural FeS x reactivity increased both the relative fraction of NO......Nitrate (NO3 −) reduction processes are important for depleting the NO3 − load from agricultural source areas before the discharge water reaches surface waters or groundwater aquifers. In this study, we experimentally demonstrate the co-occurrence of microbial iron sulfide oxidation by NO3 − (MISON......) and other NO3 −-depleting processes in a range of contrasting sediment types: sandy groundwater aquifer, non-managed minerotrophic freshwater peat and two brackish muddy sediments. Approximately 1/3 of the net NO3 − reduction was caused by MISON in three of the four environments despite the presence...

  8. Iron ore pollution in Mandovi and Zuari estuarine sediments and its fate after mining ban.

    Science.gov (United States)

    Kessarkar, Pratima M; Suja, S; Sudheesh, V; Srivastava, Shubh; Rao, V Purnachandra

    2015-09-01

    Iron ore was mined from the banded iron formations of Goa, India, and transported through the Mandovi and Zuari estuaries for six decades until the ban on mining from September 2012. Here we focus on the environmental magnetic properties of sediments from the catchment area, upstream and downstream of these estuaries, and adjacent shelf during peak mining time. Magnetic susceptibility (χ lf) and saturation isothermal remanent magnetization (SIRM) values of sediments were highest in upstream (catchment area and estuaries), decreased gradually towards downstream (catchment area and estuaries), and were lowest on the adjacent shelf. The χ lf values of the Mandovi estuary were two to fourfold higher than those in the Zuari. The sediments of these two estuaries after the mining ban showed enrichment of older magnetite and sharp decrease in the SIRM values. Although the input of ore material has been reduced after mining ban, more flushing of estuarine sediments is required for healthier environment.

  9. Moessbauer investigation of characteristic distribution of iron oxides in sediments from the Antarctica

    International Nuclear Information System (INIS)

    Kuzmann, E.; Homonnay, Z.; Vertes, A.; Garg, V.K.; De Oliveira, A.C.; De Souza Junior, P.A.; Schuch, L.A.

    2000-01-01

    Sediments from the Admirally Bay, King George Island, Antarctica, were investigated by 57 Fe Moessbauer spectroscopy, X-ray diffractometry, and radiometry. Quartz, feldspar, chlorite, calcite, dolomite, mica, kaolinite, hematite and magnetite were identified as constituent minerals in the sediment samples. The phase composition and the iron distribution among the crystallographic sites of iron-bearing minerals (silicates, magnetite and hematite) of samples from different location have been derived from the complex Moessbauer spectra. At different locations sediments has significant characteristic differences in the mineral composition, in the iron distribution among the crystallographic site of silicates, and in the specific radioactivity of Cs radionuclides. These results indicate differences in the rock formation and alteration by the sediments in this maritime part of Antarctica. There is a much higher amount of iron oxides in the sediments from south part of the geological fault across the Admirally Bay than in the north part. This can be associated with much more alteration in the rocks in the south part compared to the northern one. This finding can contribute to the question of the history of the formation and alteration of volcanic rocks in the border of Antarctica. (author)

  10. Mapping of industrial effluent on coastal sediments using EDX

    CSIR Research Space (South Africa)

    Gregory, MA

    2003-01-01

    Full Text Available isotopes [14], magnetic and rare-earth markers such as Ta and Co [15] and bacterial tracers [16]. Passive tracers are materials/substances already present in the effluent as they leave the factory or treatment works. In the case of ?sludges? from sewage... for industrial waste [1,2]. To date, while EDX has been used to determine the speciation of marine suspended particles [21], monitor the translocation and mixing of fill sands [22] and describe the source and intermixing of sea-floor sediments [23...

  11. Spatial and Temporal Variability in Sediment P Distribution and Speciation in Coastal Louisiana

    Science.gov (United States)

    Bowes, K.; White, J. R.; Maiti, K.

    2017-12-01

    Excess loading of phosphorus (P) and nitrogen (N) into aquatic systems leads to degradation of water quality and diminished important ecosystem services. In the Northern Gulf of Mexico (NGOM), excess P and N loading has led to a seasonally present hypoxic area with less than 2 mg/L O2 in bottom waters, approximating 26,000 km2 in 2017. A sequential extraction (SEDEX) method was performed on surficial sediments from five different coastal and shelf sites as a function of distance from the Mississippi River mouth in the NGOM. To better quantify temporal variability in P distribution and speciation, samples were collected during both low (August) and high (May) river flow regimes. Sequential extraction techniques have been successful in separating pools of P into exchangeable or loosely sorbed P, Fe-P, Authigenic-P, Detrital-P, and Organic-P. Preliminary results suggest Authigenic-P is approximately 3-6 times more concentrated in NGOM sediments than all other P pools. Fractionation results did not show a consistent trend with sediment depth. Sediment samples had an average moisture content of 58.72% ± 12.06% and an average bulk density of 0.582 ± 0.275 g/cm3. Continued analysis of P speciation and cycling in NGOM sediments is critical in understanding the driving force behind coastal eutrophication and informing effective nutrient management strategies.

  12. Diatoms dominate the eukaryotic metatranscriptome during spring in coastal 'dead zone' sediments.

    Science.gov (United States)

    Broman, Elias; Sachpazidou, Varvara; Dopson, Mark; Hylander, Samuel

    2017-10-11

    An important characteristic of marine sediments is the oxygen concentration that affects many central metabolic processes. There has been a widespread increase in hypoxia in coastal systems (referred to as 'dead zones') mainly caused by eutrophication. Hence, it is central to understand the metabolism and ecology of eukaryotic life in sediments during changing oxygen conditions. Therefore, we sampled coastal 'dead zone' Baltic Sea sediment during autumn and spring, and analysed the eukaryotic metatranscriptome from field samples and after incubation in the dark under oxic or anoxic conditions. Bacillariophyta (diatoms) dominated the eukaryotic metatranscriptome in spring and were also abundant during autumn. A large fraction of the diatom RNA reads was associated with the photosystems suggesting a constitutive expression in darkness. Microscope observation showed intact diatom cells and these would, if hatched, represent a significant part of the pelagic phytoplankton biomass. Oxygenation did not significantly change the relative proportion of diatoms nor resulted in any major shifts in metabolic 'signatures'. By contrast, diatoms rapidly responded when exposed to light suggesting that light is limiting diatom development in hypoxic sediments. Hence, it is suggested that diatoms in hypoxic sediments are on 'standby' to exploit the environment if they reach suitable habitats. © 2017 The Author(s).

  13. Suspended sediment concentration and optical property observations of mixed-turbidity, coastal waters through multispectral ocean color inversion

    Science.gov (United States)

    Multispectral satellite ocean color data from high-turbidity areas of the coastal ocean contain information about the surface concentrations and optical properties of suspended sediments and colored dissolved organic matter (CDOM). Empirical and semi-analytical inversion algorit...

  14. SEDIMENT PROPERTIES and Other Data from FIXED PLATFORM From Coastal Waters of California from 19780411 to 19781203 (NODC Accession 8000315)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sediment properties and other data from FIXED PLATFORM From Coastal Waters of California from April 11 to December 3, 1978. This data set consists of the results of...

  15. Empirical evidence reveals seasonally dependent reduction in nitrification in coastal sediments subjected to near future ocean acidification

    NARCIS (Netherlands)

    Braeckman, U.; Van Colen, C.; Guilini, K.; Van Gansbeke, D.; Soetaert, K.; Vincx, M.; Vanaverbeke, J.

    2014-01-01

    Research so far has provided little evidence that benthic biogeochemical cycling is affected by ocean acidification under realistic climate change scenarios. We measured nutrient exchange and sediment community oxygen consumption (SCOC) rates to estimate nitrification in natural coastal permeable

  16. Hydrocarbon contamination of coastal sediments from the Sfax area (Tunisia), Mediterranean Sea.

    Science.gov (United States)

    Louati, A; Elleuch, B; Kallel, M; Saliot, A; Dagaut, J; Oudot, J

    2001-06-01

    The coastal area off the city of Sfax (730,000 inhabitants), well-known for fisheries and industrial activities, receives high inputs of organic matter mostly anthropogenic. Eighteen stations were selected in the vicinity of the direct discharge of industrial sewage effluents in the sea in order to study the spatial distribution of the organic contamination. Surface sediments sampled in the shallow shelf were analysed for hydrocarbons by Fourier transform infrared spectroscopy, gas chromatography and gas chromatography/mass spectrometry. Total hydrocarbon distributions revealed high contamination as compared to other coastal Mediterranean sites, with an average concentration of 1865 ppm/dry weight sediment. Gas chromatographic distribution patterns, values of unresolved mixture/n-alkane ratio and distributions of steranes and hopanes confirmed a petroleum contamination of the Arabian light crude oil type. Biogenic compounds were also identified with a series of short-chain carbon-numbered n-alkenes in the carbon range 16-24.

  17. Petroleum Hydrocarbon in Surface Sediment from Coastal Area of Putatan and Papar, Sabah

    International Nuclear Information System (INIS)

    Siti Aishah Mohd Ali; Rohana Tair; Yang, S.Z.; Masni Mohd Ali

    2013-01-01

    Total petroleum hydrocarbons (TPH) and percent total organic carbon (TOC) were investigated in surface sediments from coastal area of Papar and Putatan, Sabah. Samples were collected in five different stations in each area by using Ponar grab sampler. Samples were extracted with Soxhlet, concentrated and analyzed by using UV/ VIS spectrophotometer. The overall mean and range of TPH concentrations in the sediments from coastal area of Papar and Putatan were 1.95 (0.53-4.59 mg/ kg dw Miri crude oil equivalents) and 0.85 (0.26-1.64 mg/ kg dw Miri crude oil equivalents) respectively. Meanwhile, the TOC ranged from 0.81-2.32 % and 0.35-0.81 % respectively. Statistical analysis using Pearson correlation showed no significant differences between TPH and TOC (p<0.05) in both areas. (author)

  18. Sediment Transport and Slope Stability of Ship Shoal Borrow Areas for Coastal Restoration of Louisiana

    Science.gov (United States)

    Liu, H.; Xu, K.; Bentley, S. J.; Li, C.; Miner, M. D.; Wilson, C.; Xue, Z.

    2017-12-01

    Sandy barrier islands along Louisiana coast are degrading rapidly due to both natural and anthropogenic factors. Ship Shoal is one of the largest offshore sand resources, and has been used as a borrow area for Caminada Headland Restoration Project. Our knowledge of sediment transport and infilling processes in this new sandy and dynamic borrow area is rather limited. High resolution sub-bottom seismic data, side scan sonar images, multi-beam bathymetry and laser sediment grain size data were used to study seafloor morphological evolution and pit wall stability in response to both physical and geological processes. The multi-beam bathymetry and seismic profiling inside the pit showed that disequilibrium conditions led to rapid infilling in the pits at the beginning, but this process slowed down after the pit slope became stable and topography became smooth. We hypothesize that the erosion of the adjacent seabed sediment by energetic waves and longshore currents, the supply of suspended sediment from the rivers, and the erodible materials produced by local mass wasting on pit walls are three main types of infilling sediments. Compared with mud-capped dredge pits, this sandy dredge pit seems to have more gentle slopes on pit walls, which might be controlled by the angle of repose. Infilling sediment seems to be dominantly sandy, with some mud patches on bathymetric depressions. This study helps us better understand the impacts of mining sediment for coastal restoration and improves sand resource management efforts.

  19. Reactive silica fractions in coastal lagoon sediments from the northern Gulf of Mexico

    Science.gov (United States)

    Krause, Jeffrey W.; Darrow, Elizabeth S.; Pickering, Rebecca A.; Carmichael, Ruth H.; Larson, Ashley M.; Basaldua, Jose L.

    2017-12-01

    Continental-margin sediments account for 50% of the oceanic biogenic silica burial despite covering Gulf of Mexico (nGoM), we measured sediment biogenic silica at sites removed from major freshwater discharge sources using the traditional method and a method that has been modified for deltaic systems to quantify other reactive silica pools, specifically those involved in the process of reverse weathering. The magnitude of authigenically-altered biogenic silica during our study was significant and represented, on average, 33% of the total sediment biogenic silica among core depths and sites. Additionally, there was a significant relationship between the degree to which the biogenic silica pool was authigenically altered and the source of the sediment organic matter, with lower modification in sediments corresponding with higher terrestrial organic matter. We observed no positive correlation between the magnitude of authigenic modification and sediment clay content. Thus, our findings suggest that these processes may occur within a variety of sediment compositions and add to a growing body of evidence suggesting that reverse weathering of silica in coastal systems is a significant pathway in the global silica budget.

  20. Assessing effects of changing land use practices on sediment loads in Panther Creek, north coastal California

    Science.gov (United States)

    Madej, Mary Ann; Bundros, Greg; Klein, Randy

    2011-01-01

    Revisions to the California Forest Practice Rules since 1974 were intended to increase protection of water quality in streams draining timber harvest areas. The effects of improved timber harvesting methods and road designs on sediment loading are assessed for the Panther Creek basin, a 15.4 km2 watershed in Humboldt County, north coastal California. We compute land use statistics, analyze suspended sediment discharge rating curves, and compare sediment yields in Panther Creek to a control (unlogged) stream, Little Lost Man Creek. From 1978 to 2008, 8.2 km2 (over half the watershed) was clearcut and other timber management activities (thinning, selection cuts, and so forth) affected an additional 5.9 km2. Since 1984, 40.7 km of streams in harvest units received riparian buffer strip protection. Between 2000 and 2009, 22 km of roads were upgraded and 9.7 km were decommissioned, reducing potential sediment production by an estimated 40,000 m3. Road density is currently 3.1 km/km2. Sediment rating curves from 2005 to 2010 indicate a decrease in suspended sediment concentrations when compared to the pre-1996 period, although Panther Creek still has a higher sediment yield on a per unit area basis than the control stream.

  1. Field studies of hydrodynamic conditions and fine-sediment suspension in the Kapar coastal region, Malaysia

    International Nuclear Information System (INIS)

    Abdul Kadir Ishak

    2006-01-01

    Field studies to determine the hydrodynamics and fine-sediment transport were carried out at the Kapar coastal region, on the west coast of the Malaysian Peninsula. Several observation stations were established to measure near-bed tidal currents, suspended sediment concentration (SSC), water temperature, salinity and tidal elevation. It was found that resuspension (erosion) and deposition of fine sediment occurred during every tidal cycle, with greater transport occurred during the ebb than the flood. This become the major source of fine sediment that contribute to the siltation problem in this region. The high resuspension and entrainment of sediment into the flow column was due to a high near-bed current velocity which was at its peak at 1.3 m/s (during spring tides) and easily-eroded fine particles recently settled during previous tidal cycles. Significant erosion (and deposition) took place during the spring tides but little erosion was observed during the neap. The secondary source of fine sediment is from Sungai Kelang transported to the area by ebb currents in particular during spring tides. The measurement data also showed that the current flows around an industrial construction, the Kapar power station, had been modified and greatly reduced, which had resulted in a significant siltation problem in this region. This study contributes to a better understanding of the influence of hydrodynamics on the physical processes relating to the resuspension, transport and deposition of the fine-sediment in this region. (Author)

  2. Nitrogen Cycling in Permeable Sediments: Process-based Models for Streams and the Coastal Ocean

    OpenAIRE

    Azizian, Morvarid

    2017-01-01

    Bioavailable forms of nitrogen, such as nitrate, are necessary for aquatic ecosystem productivity. Excess nitrate in aquatic systems, however, can adversely affect ecosystems and degrade both surface water and groundwater. Some of this excess nitrate can be removed in the sediments that line the bottom of rivers and coastal waters, through the exchange of water between surface water and groundwater (known as hyporheic exchange).Several process-based models have been proposed for estimating ni...

  3. Comparison of heavy metal contamination during the last decade along the coastal sediment of Pakistan: Multiple pollution indices approach.

    Science.gov (United States)

    Saher, Noor Us; Siddiqui, Asmat Saleem

    2016-04-15

    Heavy metals concentrations (Fe, Cu, Zn, Ni, Cr, Co, Pb, and Cd) were scrutinized during two monitoring years (2001 and 2011) in the coastal sediment of Pakistan. The status of metal contamination in coastal sediment was interpreted using sediment quality guidelines, and single and combined metal pollution indices. Ni, Cr, and Cd were recognized for their significant (p<0.05) intensification in the sediment during the last decade. Sediment quality guidelines recognized the frequent adverse biological effect of Ni and the occasional adverse biological effect of Cu, Cr, Pb and Cd. Single metal pollution indices (Igeo, EF, CF, and ER) revealed that sediment pollution is predominantly caused by Pb and Cd. Low to moderate contamination was appraised along the coast by multi-metal pollution indices (CD and PERI). Correlation study specifies that heavy metals were presented diverse affiliations and carriers for distribution in the sediment during the last decade. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Organochlorine pesticides in sediment and biological samples from the coastal lagoons of Nicaragua

    International Nuclear Information System (INIS)

    Montenegro, S.; Lacayo, M.; Picado, F.; Lopez, A.

    1999-01-01

    A study was carried out on the Pacific coast of Nicaragua to investigate the contamination of the coastal lagoons with residues of agricultural pesticides. Samples were taken during 1995 from the areas of Estero Real, Padre Ramos, Maderas Negras, Naranjo and Paso Caballos, and during 1996 from Aposentillo to Estero Barquito - Posoltega River. Analysis of the samples of sediment and aquatic life (fishes, oysters and bivalves) showed that they were contaminated with organochlorine pesticides. The pesticides found in the highest concentrations were toxaphene (1,734 μg.kg -1 ) and p,p-DDE (275 μg kg -1 ). These data indicate widespread contamination of the ecosystem with organochlorine pesticides in the main Pacific coastal lagoons of Nicaragua, resulting from intensive agricultural use of pesticides during the past decades. The contamination has been carried from the agricultural areas to the coastal lagoons by the rivers passing through the cultivated areas. (author)

  5. Mercury Enrichment in Sediments of the Coastal Area of Northern Latium, Italy.

    Science.gov (United States)

    Scanu, Sergio; Piazzolla, Daniele; Frattarelli, Francesco Manfredi; Mancini, Emanuele; Tiralongo, Francesco; Brundo, Maria Violetta; Tibullo, Daniele; Pecoraro, Roberta; Copat, Chiara; Ferrante, Margherita; Marcelli, Marco

    2016-05-01

    The purpose of this study was to evaluate the extent of the Hg geochemical anomaly arising in the Amiata and Tolfa complex to the coastal area of northern Latium and to examine the possible influence on this area by the Mignone River, and by the small coastal basins, which are characterized by both previous mining activities and decades of past industrial impact. The results confirm the extension of the anomaly of concentrations of Hg in the coastal area of northern Latium, with the northern sector influenced by the contributions of the Fiora and Mignone Rivers and the southern sector influenced by the contributions of minor basins. The results show high values of the Adverse Effect Index throughout the considered area and highlight the need for further investigation in order to assess the impact of human activities on the present and past values of Hg in marine sediments.

  6. Development and Application of a Cohesive Sediment Transport Model in Coastal Louisiana

    Science.gov (United States)

    Sorourian, S.; Nistor, I.

    2017-12-01

    The Louisiana coast has suffered from rapid land loss due to the combined effects of increasing the rate of eustatic sea level rise, insufficient riverine sediment input and subsidence. The sediment in this region is dominated by cohesive sediments (up to 80% of clay). This study presents a new model for calculating suspended sediment concentration (SSC) of cohesive sediments. Several new concepts are incorporated into the proposed model, which is capable of estimating the spatial and temporal variation in the concentration of cohesive sediment. First, the model incorporates the effect of electrochemical forces between cohesive sediment particles. Second, the wave friction factor is expressed in terms of the median particle size diameter in order to enhance the accuracy of the estimation of bed shear stress. Third, the erosion rate of cohesive sediments is also expressed in time-dependent form. Simulated SSC profiles are compared with field data collected from Vermilion Bay, Louisiana. The results of the proposed model agree well with the experimental data, as soon as steady state condition is achieved. The results of the new numerical models provide a better estimation of the suspended sediment concentration profile compared to the initial model developed by Mehta and Li, 2003. Among the proposed developments, the formulation of a time-dependent erosion rate shows the most accurate results. Coupling of present model with the Finite-Volume, primitive equation Community Ocean Model (FVCOM) would shed light on the fate of fine-grained sediments in order to increase overall retention and restoration of the Louisiana coastal plain.

  7. Acoustic measurement of sediment dynamics in the coastal zones using wireless sensor networks

    Science.gov (United States)

    Sudhakaran, A., II; Paramasivam, A.; Seshachalam, S.; A, C.

    2014-12-01

    Analyzing of the impact of constructive or low energy waves and deconstructive or high energy waves in the ocean are very much significant since they deform the geometry of seashore. The deformation may lead to productive result and also to the end of deteriorate damage. Constructive waves results deposition of sediment which widens the beach where as deconstructive waves results erosion which narrows the beach. Validation of historic sediment transportation and prediction of the direction of movement of seashore is essential to prevent unrecoverable damages by incorporating precautionary measurements to identify the factors that influence sediment transportation if feasible. The objective of this study is to propose a more reliable and energy efficient Information and communication system to model the Coastal Sediment Dynamics. Various factors influencing the sediment drift at a particular region is identified. Consequence of source depth and frequency dependencies of spread pattern in the presence of sediments is modeled. Property of source depth and frequency on sensitivity to values of model parameters are determined. Fundamental physical reasons for these sediment interaction effects are given. Shallow to deep water and internal and external wave model of ocean is obtained intended to get acoustic data assimilation (ADA). Signal processing algorithms are used over the observed data to form a full field acoustic propagation model and construct sound speed profile (SSP). The inversions of data due to uncertainties at various depths are compared. The impact of sediment drift over acoustic data is identified. An energy efficient multipath routing scheme Wireless sensor networks (WSN) is deployed for the well-organized communication of data. The WSN is designed considering increased life time, decreased power consumption, free of threats and attacks. The practical data obtained from the efficient system to model the ocean sediment dynamics are evaluated with remote

  8. Activity concentrations of 239+240 Pu in sediment at Sabah and Sarawak coastal areas

    International Nuclear Information System (INIS)

    Jalal Sharib; Zaharudin Ahmad; Yii Mei Wo; Hidayah Shahar

    2009-01-01

    The coastal sediment sampling was carried out in July 2004 as part of the Marine Radioactivity Database Development Project for Malaysia. The determination of plutonium, 239+240 Pu activity concentration and their distributions along the coastal areas of Sabah and Sarawak was by the alpha spectrometry counting system. Prior to counting, the radionuclides were isolated from the samples using radiochemical separation technique and mounted on a stainless steel disc by using electro-deposition. The results show that the distribution of 239+240 Pu activity concentration in coastal sediment is consistent, ranging from BDL - 1.83 Bq/kg and 0.11 - 0.84 Bq/kg dry weight, respectively. Lubok Sabanan, SB 15, in Sabah and Sungai Similajau, SR 13, in Sarawak were sampling stations that gave highest 239+240 Pu activity concentration. Overall, the 239+240 Pu activity concentration of Sabah and Sarawak are slightly higher in comparison the West Coast coastal stations of Peninsular Malaysia, and can be used as database. (Author)

  9. Phosphorus binding by poorly crystalline iron oxides in North Sea sediments

    NARCIS (Netherlands)

    Slomp, C.P.; Gaast, S. J. van der; Raaphorst, W. van

    1996-01-01

    Differential X-ray powder diffraction (DXRD) and extraction procedures were used to characterize the iron oxides present in four sediments from contrasting environments in the North Sea. Stations were located in depositional areas on the southern shelf (German Bight) and on the north-eastern

  10. Speciation of iron and manganese in the sediments of Mandovi Estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Jayakumar, D.A.; Rajendran, A.

    Several attempts have been made to study the distribution of iron and manganese in Mandovi Estuary, Goa, India. But this is the first report of its kind on the speciation of these metals in sediments from Indian waters. This study would be useful...

  11. Concentrations of organotin compounds in sediment and clams collected from coastal areas in Vietnam

    International Nuclear Information System (INIS)

    Midorikawa, Sayaka; Arai, Takaomi; Harino, Hiroya; Ohji, Madoka; Nguyen Duc Cu; Miyazaki, Nobuyuki

    2004-01-01

    Levels of butyltin (BT) and phenyltin (PT) compounds were determined in sediments and clam Meretrix spp. collected from north and central coastal areas in Vietnam. Concentrations of TBT in sediments ranged from 0.89 to 34 ng g -1 dry wt and those in clams ranged from 1.4 to 56 ng g -1 wet wt. The levels of TBT in sediments and clams from Vietnam were within limits reported from other countries. Further, the TBT level in clams was lower than the tolerable average residue level (TARL) estimated based on tolerable daily intake (TDI). Trace amounts of PTs were also found in both sediment and clam samples. In sediments from north and central Vietnam, the concentrations of TBT were highest in the order of Hue (28 ng g -1 dry wt), Cua Luc (15 ng g -1 dry wt), Sam Son (6.3 ng g -1 dry wt), and Tra Co (5.5 ng g -1 dry wt). Among the clams from north and central Vietnam, the levels of TBT in clams from Cua Luc were dramatically high at 47 ng g -1 wet wt. TBT formed the principal butyltin species in sediment at all sites studied. The ratios of TBT in sediment were higher among BT compounds at all study sites. Of total BTs, TBT was the dominant species in clams from almost all sites studied. In spatial distribution, TPT showed a pattern similar to TBT, suggesting the use of TPT as an antifouling paint. The partition coefficient between sediment and calms was calculated. The partition coefficients of TBT and TPT were 2.01 (0.56-5.5) and 9.23 (3.1-20), respectively. These results show that sediment-bound TBT is a source of contamination to clams in addition to dissolved TBT

  12. Shifts in coastal sediment oxygenation cause pronounced changes in microbial community composition and associated metabolism.

    Science.gov (United States)

    Broman, Elias; Sjöstedt, Johanna; Pinhassi, Jarone; Dopson, Mark

    2017-08-09

    A key characteristic of eutrophication in coastal seas is the expansion of hypoxic bottom waters, often referred to as 'dead zones'. One proposed remediation strategy for coastal dead zones in the Baltic Sea is to mix the water column using pump stations, circulating oxygenated water to the sea bottom. Although microbial metabolism in the sediment surface is recognized as key in regulating bulk chemical fluxes, it remains unknown how the microbial community and its metabolic processes are influenced by shifts in oxygen availability. Here, coastal Baltic Sea sediments sampled from oxic and anoxic sites, plus an intermediate area subjected to episodic oxygenation, were experimentally exposed to oxygen shifts. Chemical, 16S rRNA gene, metagenomic, and metatranscriptomic analyses were conducted to investigate changes in chemistry fluxes, microbial community structure, and metabolic functions in the sediment surface. Compared to anoxic controls, oxygenation of anoxic sediment resulted in a proliferation of bacterial populations in the facultative anaerobic genus Sulfurovum that are capable of oxidizing toxic sulfide. Furthermore, the oxygenated sediment had higher amounts of RNA transcripts annotated as sqr, fccB, and dsrA involved in sulfide oxidation. In addition, the importance of cryptic sulfur cycling was highlighted by the oxidative genes listed above as well as dsvA, ttrB, dmsA, and ddhAB that encode reductive processes being identified in anoxic and intermediate sediments turned oxic. In particular, the intermediate site sediments responded differently upon oxygenation compared to the anoxic and oxic site sediments. This included a microbial community composition with more habitat generalists, lower amounts of RNA transcripts attributed to methane oxidation, and a reduced rate of organic matter degradation. These novel data emphasize that genetic expression analyses has the power to identify key molecular mechanisms that regulate microbial community responses

  13. Nitrous Oxide Production and Fluxes from Coastal Sediments under Varying Environmental Conditions

    Science.gov (United States)

    Ziebis, W.; Wankel, S. D.; de Beer, D.; Dentinger, J.; Buchwald, C.; Charoenpong, C.

    2014-12-01

    Although coastal zones represent important contributors to the increasing levels of atmospheric nitrous oxide (N2O), it is still unclear which role benthic processes play and whether marine sediments represent sinks or sources for N2O, since interactions among closely associated microbial groups lead to a high degree of variability. In addition, coastal areas are extremely dynamic regions, often exposed to increased nutrient loading and conditions of depleted oxygen. We investigated benthic N2O fluxes and how environmental conditions affect N2O production in different sediments at 2 different geographical locations (German Wadden Sea, a California coastal lagoon). At each location, a total of 32 sediment cores were taken in areas that differed in sediment type, organic content and pore-water nutrient concentrations, as well as in bioturbation activity. Parallel cores were incubated under in-situ conditions, low oxygen and increased nitrate levels for 10 days. Zones of N2O production and consumption were identified in intact cores by N2O microprofiles at the beginning and end of the experiments. In a collaborative effort to determine the dominant sources of N2O, samples were taken throughout the course of the experiments for the determination of the isotopic composition of N2O (as well as nitrate, nitrite and ammonium). Our results indicate that both, nitrate addition and low oxygen conditions in the overlying water, caused an increase of subsurface N2O production in most sediments, with a high variability between different sediment types. N2O production in the sediments was accompanied by N2O consumption, reducing the fluxes to the water column. In general, organic rich sediments showed the strongest response to environmental changes with increased production and efflux of N2O into the overlying water. Bioturbation activity added to the complexity of N2O dynamics by an increase in nitrification-denitrification processes, as well as enhanced pore-water transport

  14. Geochemical variability of copper and iron in Oman margin sediments

    Digital Repository Service at National Institute of Oceanography (India)

    Alagarsamy, R.

    ] below the oxygen minimum zone (OMZ) during RRS Discovery cruise 211/94 (Fig.1; Table 1). Sediment samples were immediately frozen (-20 ˚ C) on board prior to transport to the laboratory where they were freeze-dried and stored at -20 ˚ C prior... in the laboratory. 2.1. Analytical Methods Sediment grain size distribution in each section of cores collected below the OMZ was determined with a Coulter Counter (Model LS 130). Water content in each section of cores collected below the OMZ was determined...

  15. Manganese and iron geochemistry in sediments underlying the redox-stratified Fayetteville Green Lake

    Science.gov (United States)

    Herndon, Elizabeth M.; Havig, Jeff R.; Singer, David M.; McCormick, Michael L.; Kump, Lee R.

    2018-06-01

    Manganese and iron are redox-sensitive elements that yield clues about biogeochemistry and redox conditions both in modern environments and in the geologic past. Here, we investigated Mn and Fe-bearing minerals preserved in basin sediments underlying Fayetteville Green Lake, a redox-stratified lake that serves as a geochemical analogue for Paleoproterozoic oceans. Synchrotron-source microprobe techniques (μXRF, μXANES, and μXRD) and bulk geochemical analyses were used to examine the microscale distribution and speciation of Mn, Fe, and S as a function of depth in the top 48 cm of anoxic lake sediments. Manganese was primarily associated with calcite grains as a manganese-rich carbonate that precipitated in the chemocline of the water column and settled through the euxinic basin to collect in lake sediments. Iron was preserved in framboidal iron sulfides that precipitated in euxinic bottom waters and underwent transformation to pyrite and marcasite in the sediments. Previous studies attribute the formation of manganese-rich carbonates to the diagenetic alteration of manganese oxides deposited in basins underlying oxygenated water. Our study challenges this paradigm by providing evidence that Mn-bearing carbonates form in the water column and accumulate in sediments below anoxic waters. Consequently, manganoan carbonates preserved in the rock record do not necessarily denote the presence of oxygenated bottom waters in ocean basins.

  16. The Study of Heavy Metals on Sediment Quality of Kuala Perlis Coastal Area

    Science.gov (United States)

    Zubir, A. A. Ahmad; Saad, F. N. Mohd; Dahalan, F. A.

    2018-03-01

    The contamination of heavy metals gives bad implications to the aquatic environment. Thus, a study was conducted to assess the sediment quality by using different contamination indices such as Enrichment Factor (EF), Geo-accumulation Index (Igeo), and Pollution Load Index (PLI). Each sediment sample was collected at the surface (0-15cm) at 5 locations based on the land use activity; jetty port (A), seaside restaurant (B), roadside area (C), power plant (D) and residential area (E). All samples were undergoes acid digestion and analyzed with AAS. Four elements identified from the sediment samples which are Cr, Cu, Pb and Zn were used to calculate the respective indices. Results show that, the highest EF value of Pb which categorized as very severe enrichment was at point E. Meanwhile minor enrichment was detected at point B for Cu while Cr and Zn at point A. Based on Igeo value the sediment quality along Kuala Perlis was in the unpolluted-moderately polluted condition (class 1). As for PLI it shows that the sediment of the coastal area is unpolluted (PLI<1). Therefore, this study revealed that, the main contributor of heavy metals in this area is Pb while the sediment quality of Kuala Perlis was in minor pollution condition.

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

    International Nuclear Information System (INIS)

    Qureshi, R.M.; Mashiatullah, A.; Akram, M.; Sajjad, M.I.; Shafiq, M.; Javed, T.; Aslam, M.

    1999-04-01

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

  18. Distribution of iron- and sulfate-reducing bacteria across a coastal acid sulfate soil (CASS environment: implications for passive bioremediation by tidal inundation

    Directory of Open Access Journals (Sweden)

    Yu-Chen eLing

    2015-07-01

    Full Text Available Coastal acid sulfate soils (CASS constitute a serious and global environmental problem. Oxidation of iron sulfide minerals exposed to air generates sulfuric acid with consequently negative impacts on coastal and estuarine ecosystems. Tidal inundation represents one current treatment strategy for CASS, with the aim of neutralizing acidity by triggering microbial iron- and sulfate-reduction and inducing the precipitation of iron-sulfides. Although well-known functional guilds of bacteria drive these processes, their distributions within CASS environments, as well as their relationships to tidal cycling and the availability of nutrients and electron acceptors, are poorly understood. These factors will determine the long-term efficacy of passive CASS remediation strategies. Here we studied microbial community structure and functional guild distribution in sediment cores obtained from ten depths ranging from 0-20 cm in three sites located in the supra-, inter- and sub-tidal segments, respectively, of a CASS-affected salt marsh (East Trinity, Cairns, Australia. Whole community 16S rRNA gene diversity within each site was assessed by 454 pyrotag sequencing and bioinformatic analyses in the context of local hydrological, geochemical and lithological factors. The results illustrate spatial overlap, or close association, of iron- and sulfate-reducing bacteria in an environment rich in organic matter and controlled by parameters such as acidity, redox potential, degree of water saturation, and mineralization. The observed spatial distribution implies the need for empirical understanding of the timing, relative to tidal cycling, of various terminal electron-accepting processes that control acid generation and biogeochemical iron and sulfur cycling.

  19. Characterization and modeling of sediment settling, consolidation, and suspension to optimize coastal Louisiana restoration

    Science.gov (United States)

    Sha, X.; Xu, K.; Bentley, S. J.; Robichaux, P. A.

    2018-04-01

    Many research efforts have been undertaken over many decades in the field of Louisiana coastal restoration, but long-term experiments for sediment suspension and consolidation in diversion-receiving basins are still limited, despite significance of this topic to ongoing restoration strategies. Sediment samples were collected from two active diversions on the Mississippi River: West Bay, a semi-enclosed bay located on the Mississippi River Delta and fed by the West Bay Diversion, and from Big Mar pond, a receiving basin of the Caernarvon freshwater diversion from the lower Mississippi River, Louisiana, USA. A dual-core Gust Erosion Microcosm System was used to measure time-series (0.5, 1, 2, 3, 4, 5, and 6-months after initial settling) erodibility at seven shear stress regimes (0.01-0.60 Pa) using experimental cores prepared with two initial sediment concentrations (60 and 120 kg m-3). A 230-cm tall settling column with nine sampling ports was used to measure the consolidation rates for initial sediment concentrations ranging from fluid mud (10 kg m-3) to dredge effluent (120 kg m-3), in combination with two levels of salinity (1 and 5). The erodibility of West Bay sediment decreased with increasing time of consolidation. The critical shear stress for resuspension increased from 0.2 Pa after 2 months to 0.45 Pa after 4 months of consolidation. The consolidation rates were inversely and exponentially related to initial sediment concentrations. Consolidation tests in salinity of 1 generally settled faster than that in salinity of 5, and consolidation tests with low sediment concentration tests generally settled faster than high-concentration tests. An exponential coefficient was added in the Sanford (2008) model to better predict the consolidation profile of both rapid early settling and slow self-weight consolidation processes. Our study suggests that enclosed basin, low salinity, relatively low sediment concentration and minimized disturbance for 4 months all favor

  20. Rapid sediment accumulation results in high methane effluxes from coastal sediments

    NARCIS (Netherlands)

    Egger, M.J.|info:eu-repo/dai/nl/372629199; Lenstra, W.K.|info:eu-repo/dai/nl/411295977; Jong, Dirk; Meysman, Filip; Sapart, C.J.|info:eu-repo/dai/nl/31400596X; van der Veen, C.; Röckmann, Thomas|info:eu-repo/dai/nl/304838233; Gonzalez, Santiago; Slomp, C.P.|info:eu-repo/dai/nl/159424003

    2016-01-01

    Globally, the methane (CH4) efflux from the ocean to the atmosphere is small, despite high rates of CH4 production in continental shelf and slope environments. This low efflux results from the biological removal of CH4 through anaerobic oxidation with sulfate in marine sediments. In some settings,

  1. Early diagenesis in the sediments of the Congo deep-sea fan dominated by massive terrigenous deposits: Part II - Iron-sulfur coupling

    Science.gov (United States)

    Taillefert, Martial; Beckler, Jordon S.; Cathalot, Cécile; Michalopoulos, Panagiotis; Corvaisier, Rudolph; Kiriazis, Nicole; Caprais, Jean-Claude; Pastor, Lucie; Rabouille, Christophe

    2017-08-01

    Deep-sea fans are well known depot centers for organic carbon that should promote sulfate reduction. At the same time, the high rates of deposition of unconsolidated metal oxides from terrigenous origin may also promote metal-reducing microbial activity. To investigate the eventual coupling between the iron and sulfur cycles in these environments, shallow sediment cores (Congo River deep-sea fan ( 5000 m) were profiled using a combination of geochemical methods. Interestingly, metal reduction dominated suboxic carbon remineralization processes in most of these sediments, while dissolved sulfide was absent. In some 'hotspot' patches, however, sulfate reduction produced large sulfide concentrations which supported chemosynthetic-based benthic megafauna. These environments were characterized by sharp geochemical boundaries compared to the iron-rich background environment, suggesting that FeS precipitation efficiently titrated iron and sulfide from the pore waters. A companion study demonstrated that methanogenesis was active in the deep sediment layers of these patchy ecosystems, suggesting that sulfate reduction was promoted by alternative anaerobic processes. These highly reduced habitats could be fueled by discrete, excess inputs of highly labile natural organic matter from Congo River turbidites or by exhumation of buried sulfide during channel flank erosion and slumping. Sulfidic conditions may be maintained by the mineralization of decomposition products from local benthic macrofauna or bacterial symbionts or by the production of more crystalline Fe(III) oxide phases that are less thermodynamically favorable than sulfate reduction in these bioturbated sediments. Overall, the iron and sulfur biogeochemical cycling in this environment is unique and much more similar to a coastal ecosystem than a deep-sea environment.

  2. Mercury remediation in wetland sediment using zero-valent iron and granular activated carbon.

    Science.gov (United States)

    Lewis, Ariel S; Huntington, Thomas G; Marvin-DiPasquale, Mark C; Amirbahman, Aria

    2016-05-01

    Wetlands are hotspots for production of toxic methylmercury (MeHg) that can bioaccumulate in the food web. The objective of this study was to determine whether the application of zero-valent iron (ZVI) or granular activated carbon (GAC) to wetland sediment could reduce MeHg production and bioavailability to benthic organisms. Field mesocosms were installed in a wetland fringing Hodgdon Pond (Maine, USA), and ZVI and GAC were applied. Pore-water MeHg concentrations were lower in treated compared with untreated mesocosms; however, sediment MeHg, as well as total Hg (THg), concentrations were not significantly different between treated and untreated mesocosms, suggesting that smaller pore-water MeHg concentrations in treated sediment were likely due to adsorption to ZVI and GAC, rather than inhibition of MeHg production. In laboratory experiments with intact vegetated sediment clumps, amendments did not significantly change sediment THg and MeHg concentrations; however, the mean pore-water MeHg and MeHg:THg ratios were lower in the amended sediment than the control. In the laboratory microcosms, snails (Lymnaea stagnalis) accumulated less MeHg in sediment treated with ZVI or GAC. The study results suggest that both GAC and ZVI have potential for reducing MeHg bioaccumulation in wetland sediment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Mercury remediation in wetland sediment using zero-valent iron and granular activated carbon

    Science.gov (United States)

    Lewis, Ariel S.; Huntington, Thomas G.; Marvin-DiPasquale, Mark C.; Amirbahman, Aria

    2016-01-01

    Wetlands are hotspots for production of toxic methylmercury (MeHg) that can bioaccumulate in the food web. The objective of this study was to determine whether the application of zero-valent iron (ZVI) or granular activated carbon (GAC) to wetland sediment could reduce MeHg production and bioavailability to benthic organisms. Field mesocosms were installed in a wetland fringing Hodgdon Pond (Maine, USA), and ZVI and GAC were applied. Pore-water MeHg concentrations were lower in treated compared with untreated mesocosms; however, sediment MeHg, as well as total Hg (THg), concentrations were not significantly different between treated and untreated mesocosms, suggesting that smaller pore-water MeHg concentrations in treated sediment were likely due to adsorption to ZVI and GAC, rather than inhibition of MeHg production. In laboratory experiments with intact vegetated sediment clumps, amendments did not significantly change sediment THg and MeHg concentrations; however, the mean pore-water MeHg and MeHg:THg ratios were lower in the amended sediment than the control. In the laboratory microcosms, snails (Lymnaea stagnalis) accumulated less MeHg in sediment treated with ZVI or GAC. The study results suggest that both GAC and ZVI have potential for reducing MeHg bioaccumulation in wetland sediment.

  4. Methane and sulfate dynamics in sediments from mangrove-dominated tropical coastal lagoons, Yucatan, Mexico

    Science.gov (United States)

    Chuang, P. C.; Young, Megan B.; Dale, Andrew W.; Miller, Laurence G.; Herrera-Silveira, Jorge A.; Paytan, Adina

    2016-01-01

    Porewater profiles in sediment cores from mangrove-dominated coastal lagoons (Celestún and Chelem) on the Yucatán Peninsula, Mexico, reveal the widespread coexistence of dissolved methane and sulfate. This observation is interesting since dissolved methane in porewaters is typically oxidized anaerobically by sulfate. To explain the observations we used a numerical transport-reaction model that was constrained by the field observations. The model suggests that methane in the upper sediments is produced in the sulfate reduction zone at rates ranging between 0.012 and 31 mmol m−2 d−1, concurrent with sulfate reduction rates between 1.1 and 24 mmol SO42− m−2 d−1. These processes are supported by high organic matter content in the sediment and the use of non-competitive substrates by methanogenic microorganisms. Indeed sediment slurry incubation experiments show that non-competitive substrates such as trimethylamine (TMA) and methanol can be utilized for microbial methanogenesis at the study sites. The model also indicates that a significant fraction of methane is transported to the sulfate reduction zone from deeper zones within the sedimentary column by rising bubbles and gas dissolution. The shallow depths of methane production and the fast rising methane gas bubbles reduce the likelihood for oxidation, thereby allowing a large fraction of the methane formed in the sediments to escape to the overlying water column.

  5. Polychlorinated biphenyls in sediments of selected sites of the Moroccan coastal zone

    Energy Technology Data Exchange (ETDEWEB)

    Piazza, R.; Ferrari, S.; Moret, I.; Gambaro, A. [Univ. Ca Foscari, Venezia (Italy). Dept. of Environmental Sciences; Le Moumni, B. [Univ. Abdelmaleck Essaadi, Tangier (Morocco). Dept. of Earth Sciences and Oceanology; Bellucci, L.G.; Frignani, M. [ISMAR-CNR, Sezione di Geologia Marina, Bologna (Italy); Zangrando, R. [IDPA-CNR, Venezia (Italy)

    2004-09-15

    A good knowledge of sources of contaminants, distribution mechanisms, sites where chemicals tend to accumulate, potential risk and actual danger to the human and environmental health is fundamental to design a policy for the environment. In this respect, it is important to recognize that sediments can keep a record of the conditions of the environment at the time of their deposition and accumulation and hence can be used to reconstruct history and trends of contamination processes. Furthermore, actively accreting salt marshes, due to the lack of sediment reworking, may provide a relatively high resolution record of atmospheric fluxes. On the other hand, transition coastal environments are of particular importance because of their position between the inland sources and the sea, which is the final repository of all the materials mobilized from the continent. In order to assess the level of PCB contamination in key areas of coastal Morocco we chose to analyse sediments from the Nador (NAD) and the Moulay Bousselham (MB) lagoons, the terminal tract of the Martil River (MR), the port of Tangier (TG) and a soil taken close to the industrial town of Tetouan (TS). The first two were chosen because of their high environmental value, the others as representative of zones potentially contaminated.

  6. Distribution of basic sediments (bedload transport) on changes in coastal coastline Donggala, Central Sulawesi Province, Indonesia

    Science.gov (United States)

    Amiruddin

    2018-03-01

    This study entitled "Distribution of Bedload Transport Against Coastline Changes in Donggala Coast", the formulation of the problem (1) how much of the estimated bedload transport in Donggala Bodies; (2) where were the location of erosion and sedimentation strong point based on the estimation of bed load transport; (3) the extent to which the prediction of shoreline change rate of transport of sediments in coastal areas Donggala. This study aims to: (1) the calculation of estimated bed load transport in Donggala waters; (2) determining the location of the point of erosion and sedimentation strong basis of estimated bedload transport; (3) the prediction of shoreline change rate of transport of sediments in coastal areas Donggala.The survey method used in this research to collect primary data include: (1) decision point waypoint coordinates of each location of measurement; (2) measurement of height, period and direction of the waves; (3) a large measurement of sediment transport; (4) The angle measurement coastline, angle of attack and wave direction, and secondary data include: (1) information from the public; (2) the physical condition data field. The results showed that: (1) general estimate sediment transport base in each location data collection is varied. This is due to the different points of the coastline as well as the angle of attack of the shoreline waters broke Donggala; (2) strong abrasion at the study site occurs at the point Ts4 (622.75 m3/yr) and TS11 (755.25 m3/yr) located in the Village Tosale and point Tw7 and Tw17 (649.25 m3/yr) in Village of Towale. As for the strong sedimentation occurs at the point Ts3 (450.50 m3/yr) located in the Village Tosale and Tg3 point (357.75 m3/yr) located in the Village Tolonggano; (3) of the predicted outcome coastline changes based on the input data estimate sediment transport, beaches and waves parameters is seen that the changes in the location prophyl coastline tends toward research into or undergo a process of

  7. Monitoring of suspended sediment variation using Landsat and MODIS in the Saemangeum coastal area of Korea.

    Science.gov (United States)

    Min, Jee-Eun; Ryu, Joo-Hyung; Lee, Seok; Son, Seunghyun

    2012-02-01

    Suspended sediment concentration (SS) is an important indicator of marine environmental changes due to natural causes such as tides, tidal currents, and river discharges, as well as human activities such as construction in coastal regions. In the Saemangeum area on the west coast of Korea, construction of a huge tidal dyke for land reclamation has strongly influenced the coastal environment. This study used remotely sensed data to analyze the SS changes in coastal waters caused by the dyke construction. Landsat and MODIS satellite images were used for the spatial analysis of finer patterns and for the detailed temporal analysis, respectively. Forty Landsat scenes and 105 monthly composite MODIS images observed during 1985-2010 were employed, and four field campaigns (from 2005 to 2006) were performed to verify the image-derived SS. The results of the satellite data analyses showed that the seawater was clear before the dyke construction, with SS values lower than 20 g/m(3). These values increased continuously as the dyke construction progressed. The maximum SS values appeared just before completion of the fourth dyke. Values decreased to below 5 g/m(3) after dyke construction. These changes indicated tidal current modification. Some eddies and plumes were observed in the images generated from Landsat data. Landsat and MODIS can reveal that coastal water turbidity was greatly reduced after completion of the construction. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Sediment fluxes from California Coastal Rivers: the influences of climate, geology, and topography

    Science.gov (United States)

    Andrews, E.D.; Antweiler, Ronald C.

    2012-01-01

    The influences of geologic and climatic factors on erosion and sedimentation processes in rivers draining the western flank of the California Coast Range are assessed. Annual suspended, bedload, and total sediment fluxes were determined for 16 river basins that have hydrologic records covering all or most of the period from 1950 to 2006 and have been relatively unaffected by flow storage, regulation, and depletion, which alter the downstream movement of water and sediment. The occurrence of relatively large annual sediment fluxes are strongly influenced by the El Nino–Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). The frequency of relatively large annual sediment fluxes decreases from north to south during La Nina phases and increases from north to south during El Nino phases. The influence of ENSO is modulated over a period of decades by the PDO, such that relatively large annual sediment fluxes are more frequent during a La Nina phase in conjunction with a cool PDO and during an El Nino phase in conjunction with a warm PDO. Values of mean annual sediment flux, , were regressed against basin and climatic characteristics. Basin area, bedrock erodibility, basin relief, and precipitation explain 87% of the variation in from the 16 river basins. Bedrock erodibility is the most significant characteristic influencing . Basin relief is a superior predictor of compared with basin slope. is nearly proportional to basin area and increases with increasing precipitation. For a given percentage change, basin relief has a 2.3-fold greater effect on than a similar change in precipitation. The estimated natural from all California coastal rivers for the period 1950–2006 would have been approximately 85 million tons without flow storage, regulation, and depletion; the actual has been approximately 50 million tons, because of the effects of flow storage, regulation, and depletion.

  9. Chemistry and behaviour of B, Ca and Mg in interstitial waters of sediments from the coastal and estuarine regions of Mandovi river along the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Shirodkar, P.V.; SenGupta, R.

    Interstitial waters of coastal and estuarine sediments show enrichment of B and Ca and a decrease in Mg. Increase in interstitial B in sediments is due to the downward diffusion from overlying water and release from solid phases by physicochemical...

  10. Dissolved inorganic carbon and alkalinity fluxes from coastal marine sediments: Model estimates for different shelf environments and sensitivity to global change

    NARCIS (Netherlands)

    Krumins, V.; Gehlen, M.; Arndt, S.; Van Cappellen, P.; Regnier, P.

    2013-01-01

    We present a one-dimensional reactive transport model to estimate benthic fluxes of dissolved inorganic carbon (DIC) and alkalinity (AT) from coastal marine sediments. The model incorporates the transport processes of sediment accumulation, molecular diffusion, bioturbation and bioirrigation,

  11. Organic matter accumulation and degradation in subsurface coastal sediments: a model-based comparison of rapid sedimentation and aquifer transport

    Directory of Open Access Journals (Sweden)

    J. M. Holstein

    2010-11-01

    Full Text Available The redox succession in shallow marine sediments generally exhibits a predictable pattern. Pore water profiles from a back barrier tidal flat in the German Wadden Sea depart from the expected redox zoning. Instead, a sulfate minimum zone associated with a sulfate-methane-sulfate double interface and a distinct ammonium peak at 1.5 m below sea floor (mbsf is displayed. Such evidence for significant degradation of organic matter (OM in subsurface layers is challenging our understanding of tidal flat biogeochemistry as little is known about processes that relocate reactive OM into layers far distant from the sediment-water interface. The objectives of our model study were to identify possible mechanisms for the rapid transport of organic matter to subsurface layers that cause the reversed redox succession and to constrain several important biogeochemical control parameters. We compared two scenarios for OM transfer: rapid sedimentation and burial of OM as well as lateral advection of suspended POM. Using a diagenetic model, uncertain process parameters, in particular those connected to OM degradation and (vertical or lateral transport, are systematically calibrated using field data.

    We found that both scenarios, advection and sedimentation, had solutions consistent with the observed pore water profiles. For this specific site, however, advective transport of particulate material had to be rejected since the reconstructed boundary conditions were rather improbable. In the alternative deposition set-up, model simulations suggested the deposition of the source OM about 60 yrs before cores were taken. A mean sedimentation rate of approximately 2 cm yr−1 indicates substantial changes in near coast tidal flat morphology, since sea level rise is at a much lower pace. High sedimentation rates most probably reflect the progradation of flats within the study area. These or similar morphodynamic features also occur in other coastal areas

  12. Magnetite production and transformation in the methanogenic consortia from coastal riverine sediments.

    Science.gov (United States)

    Zheng, Shiling; Wang, Bingchen; Liu, Fanghua; Wang, Oumei

    2017-11-01

    Minerals that contain ferric iron, such as amorphous Fe(III) oxides (A), can inhibit methanogenesis by competitively accepting electrons. In contrast, ferric iron reduced products, such as magnetite (M), can function as electrical conductors to stimulate methanogenesis, however, the processes and effects of magnetite production and transformation in the methanogenic consortia are not yet known. Here we compare the effects on methanogenesis of amorphous Fe (III) oxides (A) and magnetite (M) with ethanol as the electron donor. RNA-based terminal restriction fragment length polymorphism with a clone library was used to analyse both bacterial and archaeal communities. Iron (III)-reducing bacteria including Geobacteraceae and methanogens such as Methanosarcina were enriched in iron oxide-supplemented enrichment cultures for two generations with ethanol as the electron donor. The enrichment cultures with A and non-Fe (N) dominated by the active bacteria belong to Veillonellaceae, and archaea belong to Methanoregulaceae and Methanobacteriaceae, Methanosarcinaceae (Methanosarcina mazei), respectively. While the enrichment cultures with M, dominated by the archaea belong to Methanosarcinaceae (Methanosarcina barkeri). The results also showed that methanogenesis was accelerated in the transferred cultures with ethanol as the electron donor during magnetite production from A reduction. Powder X-ray diffraction analysis indicated that magnetite was generated from microbial reduction of A and M was transformed into siderite and vivianite with ethanol as the electron donor. Our data showed the processes and effects of magnetite production and transformation in the methanogenic consortia, suggesting that significantly different effects of iron minerals on microbial methanogenesis in the iron-rich coastal riverine environment were present.

  13. The assessment of sediment screening risk in Venice Lagoon and other coastal areas using international sediment quality guidelines

    International Nuclear Information System (INIS)

    Apitz, S.A.; Barbanti, A.; Bocci, M.; Delaney, E.; Bernstein, A.G.; Montobbio, L.

    2007-01-01

    A number of studies carried out in recent years have shown the presence of a wide range of contaminants in the Venice Lagoon. It is important to have a good understanding of the ecological quality of Venice Lagoon sediments, in order to: i) define and locate areas where a threat to the environment is present and therefore an intervention is needed (i.e. in situ assessment and management); and ii) define sustainable and environmentally correct ways of managing sediments which are to be dredged for navigational purposes or in relation to other interventions (i.e., ex situ management). Materials and Methods: To examine how various regional and international SQGs 'classed' screening risk in Venice Lagoon sediments, data on median contaminant levels in surface sediments in Venice Lagoon resulting from a literature review were compared to a range of local and international sediment quality guidelines (SQGs). Then data on sediment contaminant levels in various areas and sub-basins of Venice Lagoon (main Lagoon, Porto Marghera and Venice City Canals) and in other regional and international transitional and coastal ecosystems with various levels of human impact (urbanization and industrialization) were evaluated based upon a selected consensus-based SQG. Finally, screening sediment quality for all of Venice Lagoon was mapped and contoured, relative to this consensus-based SQG and briefly compared with direct toxicity measurement through a battery of bioassays. Results: SQGs allow the sediment areas to be put in terms of potential, or screening, risk. Although there were some differences depending upon which specific SQGs were applied, the Venice SQGs and other international SQGs provided the same general picture of screening risk in Venice Lagoon despite geographic differences. Venice Lagoon South has the lowest screening risk levels, Venice Lagoon Central/North has the highest (and is nearest to the Porto Marghera and Venice City Canals sites). Discussion: The Venice

  14. Including granulometric sediment coastal data composition into the Black Sea GIS

    Science.gov (United States)

    Zhuk, Elena; Khaliulin, Alexey; Krylenko, Marina; Krylenko, Viacheslav; Zodiatis, George; Nikolaidis, Marios; Nikolaidis, Andreas

    2017-09-01

    The module structure of the Black Sea GIS allows the increasing of its functionality, including new data types and defining new procedures accessing them, their visualization and integration with existing data by their conjoint processing and representation. The Black Sea GIS is released as free software; Mapserver is used as a mapping service; MySQL DBMS works with relational data. A new additional feature provided, is the ability of including coastal data obtained in SB SIO RAS. The data represent granulometric composition of the Anapa bay-bar sediments. The Anapa bay-bar is an accumulative sand form (about 50 km long) located on the northwest Russian Black Sea coast. The entire bay-bar and especially its southern part with sand beaches 50-200 m wide is intensively used in recreation. This work is based on the results of field studies of 2010-2014 in the southern part of the Anapa bay-bar researched by scientists of the Shirshov Institute of Oceanology RAS. Since the shore under consideration has no clearly pronounced reference points, "virtual" points located within 1 km distance from each other were selected. Transversal profiles cross these points. The granulometric composition was studied along with 45 profiles. The samples taken in every profile were from the most characteristic morphological parts of the beach. In this study we used shoreline zone samples. Twenty one granule fractions (mm) were separated in the laboratory. The module which processes coastal data allows to select coastal data based on territory/region and granulometric sediment composition. Also, it allows to visualize coastal maps with user-selected features combined with other GIS data.

  15. Assessment of Selected Heavy Metals in Seawater and Sediment at Klang Coastal Area Malaysia

    International Nuclear Information System (INIS)

    Noor Aziatul Aini Hamzan; Farah Fardiana Mohamad Zaini; Mohd Ismail Ibrahim; Nik Azlin Nik Ariffin

    2015-01-01

    Sediments are capable of transporting loads of adsorbed nutrients, pesticides, heavy metals, and other toxins. In this study, the samples of sediment were collected from four sampling points (Kapar, Sungai Puloh, Sementa and North Port) using sediment core sampler. The cores then was sub-sampled by slicing into 1 cm slices and dried at 60 degree Celsius until mass become constant and the weight recorded. The samples were pulverized and sieved through 220 μm stainless steel sieves. Each sub-sample digested using aqua regia acids. For seawater, the samples were evaporated using the hotplate at 60 degree Celsius. The concentration of heavy metals was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The highest concentration of copper, zinc, iron and lead was observed from seawater samples obtained from Sementa while highest concentration of cadmium was found from Kapar samples). Most of the bottom seawater gives high concentration of the heavy metal compare to the surface. For sediment, the overall concentration of heavy metal in each layer was fluctuated. From the analysis, there is a significant correlation for overall selected heavy metals and the samples (seawater and sediment) that study in this area. (author)

  16. Diversity and composition of sediment bacteria in subtropical coastal wetlands of North Stradbroke Island, Queensland, Australia

    Science.gov (United States)

    Chuvochina, Maria; Sampayo, Eugenia; Welti, Nina; Hayes, Matthew; Lu, Yang; Lovelock, Catherine; Lockington, David

    2013-04-01

    Coastal wetlands provide a wide variety of important ecosystem services but continue to suffer disturbance, degradation and deforestation. Sediment bacteria are responsible for major nutrient transformation and recycling in these ecosystems. Insight into microbial community composition and the factors that determine them may improve our understanding of biogeochemical processes, food web dynamics, biodegradation processes and, thus, help to develop the management strategies for preserving the ecosystem health and services. Characterizing shifts in community taxa along environmental gradients has been shown to provide a useful tool for determining the major drivers affecting community structure and function. North Stradbroke Island (NSI) in Southern Queensland presents considerable habitat diversity including variety of groundwater dependent ecosystems such as lakes, swamps, sedge-like salt marshes and mangroves. Ecological responses of continuous groundwater extraction for municipal purposes and sand mining operations on NSI are still need to be assessed in order to protect its unique environment. Changes in coastal hydrology due to either climate change or human activity may directly affect microbial populations and, thus, biogeochemical cycles of nutrients. These may result in altering/losing some ecosystem services provided by coastal wetlands. In this study we examine microbial diversity and determine environmental controls on bacterial community structure along a natural transition from freshwater forested wetland (melaleuca woodland), sedge-like salt marsh and into mangroves located at NSI. The study area is characterized by significant groundwater flow, nutrient limitation and sharp transition from one ecosystem type to another. Sediment cores (0-5 cm and 20-25 cm depth) were collected from three representative sites of each zone (mangroves - salt marsh - freshwater wetland) along the salinity gradient in August 2012. Subsamples were set aside for use in

  17. Control of manganese and iron in Skagerrak sediments (northeastern North Sea)

    Digital Repository Service at National Institute of Oceanography (India)

    Rajendran, A.; DileepKumar, M.; Bakker, J.F.

    - 80. I00 E E 40" "I- l-- n 6Or hl 80" ioo (a) MANGANESE ( mmo\\[. kg ''1 ) ,? 2,0 3p ~, A ,o =o 40" 6O" I00 B (b) IRON (mmol. kg '-I ) 4o 6o- 8O" IO( ~o,oo ,ooo i I I 590 I A o 20- . 40" 60" ,J o 2o 40" 60" 80- IOO... in these sediments, expressed as change in concentration with time on a volume basis of sediments or pore water \\[see Berner (1980) for a discussion \\], the steady-state equations of Burdige and Gieskes (1983) have been used. These are, ( 1 ) oxic zone...

  18. Iron ore pollution in Mandovi and Zuari estuarine sediments and its fate after mining ban

    Digital Repository Service at National Institute of Oceanography (India)

    Kessarkar, P.M.; Suja, S.; Sudheesh, V.; Srivastava, S.; Rao, V.P.

    ). Another possibility could be formation of ferritized iron crust (Mathe et al. 1997) during lateritic weathering. Magnetic properties of upstream sediments of Ma-Zu estuaries Sediments from the upstream of Mandovi (M6-M9) and Zuari (Z6-Z9) estuaries... for late Quaternary climatic change. Marine Geology, 220, 59-82. Maher, B. A., & Taylor, R. M. (1988). Formation of ultrafine-grained magnetite in soils. Nature, 336, 368-370. Mathe, P. E., Rochette, P., & Colin, F. (1997). The origin of magnetic...

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

    Directory of Open Access Journals (Sweden)

    Nikki Dijkstra

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

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

    Science.gov (United States)

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

    2014-01-01

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

  1. Baseline evaluation of sediment contamination in the shallow coastal areas of Saudi Arabian Red Sea

    KAUST Repository

    Ruiz Compean, Pedro Javier

    2017-09-12

    Despite the growing recognition of the importance of water and sediment quality there is still limited information on contamination levels in many regions globally including the Red Sea. This study provides a comprehensive assessment of three classes of contaminants (Polycyclic Aromatic Hydrocarbons - PAH; metals; plastics) in coastal sediments along the Saudi Arabian Red Sea mainly collected using grabs. Background concentrations are provided for metals in the region. Concentrations of metals and PAH were generally low in comparison to international guidelines. A clear relationship between the concentration of metals and anthropogenic sources was not always apparent and dust and vegetation may be relevant players in the region. Microplastic items (mainly polyethylene) were abundant (reaching up to 1gm−2 and 160piecesm−2) and in general associated with areas of high human activity. This study provides critical information for future monitoring and the development of national policies within the Red Sea region.

  2. Baseline evaluation of sediment contamination in the shallow coastal areas of Saudi Arabian Red Sea.

    Science.gov (United States)

    Ruiz-Compean, Pedro; Ellis, Joanne; Cúrdia, João; Payumo, Richard; Langner, Ute; Jones, Burton; Carvalho, Susana

    2017-10-15

    Despite the growing recognition of the importance of water and sediment quality there is still limited information on contamination levels in many regions globally including the Red Sea. This study provides a comprehensive assessment of three classes of contaminants (Polycyclic Aromatic Hydrocarbons - PAH; metals; plastics) in coastal sediments along the Saudi Arabian Red Sea mainly collected using grabs. Background concentrations are provided for metals in the region. Concentrations of metals and PAH were generally low in comparison to international guidelines. A clear relationship between the concentration of metals and anthropogenic sources was not always apparent and dust and vegetation may be relevant players in the region. Microplastic items (mainly polyethylene) were abundant (reaching up to 1gm -2 and 160piecesm -2 ) and in general associated with areas of high human activity. This study provides critical information for future monitoring and the development of national policies within the Red Sea region. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Baseline evaluation of sediment contamination in the shallow coastal areas of Saudi Arabian Red Sea

    KAUST Repository

    Ruiz Compean, Pedro Javier; Ellis, Joanne; Curdia, Joao; Payumo, Richard; Langner, Ute; Jones, Burton; Carvalho, Susana

    2017-01-01

    Despite the growing recognition of the importance of water and sediment quality there is still limited information on contamination levels in many regions globally including the Red Sea. This study provides a comprehensive assessment of three classes of contaminants (Polycyclic Aromatic Hydrocarbons - PAH; metals; plastics) in coastal sediments along the Saudi Arabian Red Sea mainly collected using grabs. Background concentrations are provided for metals in the region. Concentrations of metals and PAH were generally low in comparison to international guidelines. A clear relationship between the concentration of metals and anthropogenic sources was not always apparent and dust and vegetation may be relevant players in the region. Microplastic items (mainly polyethylene) were abundant (reaching up to 1gm−2 and 160piecesm−2) and in general associated with areas of high human activity. This study provides critical information for future monitoring and the development of national policies within the Red Sea region.

  4. Nutrient fluxes across sediment-water interface in Bohai Bay Coastal Zone, China.

    Science.gov (United States)

    Mu, Di; Yuan, Dekui; Feng, Huan; Xing, Fangwei; Teo, Fang Yenn; Li, Shuangzhao

    2017-01-30

    Sediment cores and overlying water samples were collected at four sites in Tianjin Coastal Zone, Bohai Bay, to investigate nutrient (N, P and Si) exchanges across the sediment-water interface. The exchange fluxes of each nutrient species were estimated based on the porewater profiles and laboratory incubation experiments. The results showed significant differences between the two methods, which implied that molecular diffusion alone was not the dominant process controlling nutrient exchanges at these sites. The impacts of redox conditions and bioturbation on the nutrient fluxes were confirmed by the laboratory incubation experiments. The results from this study showed that the nutrient fluxes measured directly from the incubation experiment were more reliable than that predicted from the porewater profiles. The possible impacts causing variations in the nutrient fluxes include sewage discharge and land reclamation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Conductive particles enable syntrophic acetate oxidation between Geobacter and Methanosarcina from coastal sediments

    DEFF Research Database (Denmark)

    Rotaru, Amelia-Elena; Calabrese, Federica; Stryhanyuk, Hryhoriy

    2017-01-01

    pressure and their survival depends on successful partnership. Here we demonstrate that conductive minerals facilitate a SAO partnership between Geobacter and Methanosarcina from the coastal sediments of the Bothnian Bay, Baltic Sea. Bothnian methanogenic sediments showed a high apparent isotopic...... fractionation (αc 1.07) characteristic of CO2-reductive methanogenesis. The native community was represented by electrogens such as Geobacter and methanogens like Methanosarcina. Upon the addition of conductive particles (activated carbon and magnetite), methanogenesis from acetate increased fourfold. Geobacter...... (96% related to G. psychrophilus) and Methanosarcina (99% related to M. subterranea) dominated the conductive particle-spiked SAO communities. Using NanoSIMS we demonstrated that during SAO, Geobacter incorporated 82% of the labeled acetate as compared to only 18% by Methanosarcina. At the same time...

  6. HEAVY METAL AND ANTIBIOTIC RESISTANCE BACTERIA IN MARINE SEDIMENT OF PAHANG COASTAL WATER

    Directory of Open Access Journals (Sweden)

    Zaima Azira

    2018-01-01

    Full Text Available The presence of heavy metal and antibiotic resistance bacteria in the marine sediment may indicate heavy metal pollution and antibiotic abuse present in the environment. In this study, a total of 89 bacteria isolated from sediment collected in Teluk Chempedak and Pantai Batu Hitam of Pahang coastal water underwent heavy metal resistance test against Chromium, Cadmium, Nickel, Copper and Cobalt. Previously, these isolates were found to exhibit antibiotic resistance capabilities to at least 5 antibiotics tested. Heavy metal resistance pattern for isolates from Teluk Chempedak was in the form of Cr > Ni >Co >Cd = Cu while for isolates from Pantai Batu Hitam showed a pattern of Cr = Ni >Co >Cu >Cd. Further investigation on the identity of selected isolates that exhibited both antibiotic and heavy metals resistance capabilities using 16S rRNA gene sequences revealed isolates with closest similarities to Staphylococcus saprophyticus and Brevundimonas vesicularis..

  7. Trace metal distribution in sediments of the Pearl River Estuary and the surrounding coastal area, South China

    International Nuclear Information System (INIS)

    Ip, Carman C.M.; Li Xiangdong; Zhang Gan; Wai, Onyx W.H.; Li, Y.-S.

    2007-01-01

    Surface sediments and sediment cores collected at the Pearl River Estuary (PRE) and its surrounding coastal area were analysed for total metal concentrations, chemical partitioning, and Pb isotopic compositions. The distribution of Cu, Cr, Pb, and Zn demonstrated a typical diffusion pattern from the land to the direction of the sea. Two hotspots of trace metal contamination were located at the mixed zone between freshwater and marine waters. The enrichment of metals in the sediments could be attributed to the deposition of the dissolved and particulate trace metals in the water column at the estuarine area. The similar Pb isotopic signatures of the sediments at the PRE and its surrounding coastal area offered strong evidence that the PRE was a major source of trace metals to the adjacent coastal area. Slightly lower 206 Pb/ 207 Pb ratios in the coastal sediments may indicate other inputs of Pb in addition to the PRE sources, including the inputs from Hong Kong and other parts of the region. - The distribution of trace metals in sediments reflected contaminant sources, physical and chemical deposition processes

  8. Land-based sources of marine pollution: Pesticides, PAHs and phthalates in coastal stream water, and heavy metals in coastal stream sediments in American Samoa

    International Nuclear Information System (INIS)

    Polidoro, Beth A.; Comeros-Raynal, Mia T.; Cahill, Thomas; Clement, Cassandra

    2017-01-01

    The island nations and territories of the South Pacific are facing a number of pressing environmental concerns, including solid waste management and coastal pollution. Here we provide baseline information on the presence and concentration of heavy metals and selected organic contaminants (pesticides, PAHs, phthalates) in 7 coastal streams and in surface waters adjacent to the Futiga landfill in American Samoa. All sampled stream sediments contained high concentrations of lead, and some of mercury. Several coastal stream waters showed relatively high concentrations of diethyl phthalate and of organophosphate pesticides, above chronic toxicity values for fish and other aquatic organisms. Parathion, which has been banned by the US Environmental Protection Agency since 2006, was detected in several stream sites. Increased monitoring and initiatives to limit non-point source land-based pollution will greatly improve the state of freshwater and coastal resources, as well as reduce risks to human health in American Samoa. - Highlights: • Several coastal stream sediments in American Samoa are high in lead and mercury. • Organophosphate pesticides, including Parathion, are present in coastal streams. • More research is needed on the sources, fate and impacts of these contaminants.

  9. Different techniques of excess 210Pb for sedimentation rate estimation in the Sarawak and Sabah coastal waters

    International Nuclear Information System (INIS)

    Zal Uyun Wan Mahmood; Zaharudin Ahmad; Abdul Kadir Ishak; Che Abdul Rahim Mohamed

    2010-01-01

    Sediment core samples were collected at eight stations in the Sarawak and Sabah coastal waters using a gravity box corer to estimate sedimentation rates based on the activity of excess 210 Pb. The sedimentation rates derived from four mathematical models of CIC, Shukla-CIC, CRS and ADE were generally shown in good agreement with similar or comparable value at all stations. However, based on statistical analysis of independent sample t-test indicated that Shukla-CIC model was the most accurate, reliable and suitable technique to determine the sedimentation rate in the study area. (author)

  10. Environmental assessment of coastal surface sediments at Tarut Island, Arabian Gulf (Saudi Arabia)

    International Nuclear Information System (INIS)

    Youssef, Mohamed; El-Sorogy, Abdelbaset; Al Kahtany, Khaled; Al Otiaby, Naif

    2015-01-01

    Highlights: • The present work deal with the environmental assessment of Tarut Island Coastal area. • Thirty eight surface sediments samples have been chemically analyzed. • Thirteen major and trace metals have been recorded. • The area of study is highly polluted with Arsenic and Mercury. - Abstract: Thirty eight surface sediments samples have been collected in the area around Tarut Island, Saudi Arabian Gulf to determine the spatial distribution of metals, and to assess the magnitude of pollution. Total concentrations of Fe, Mn, As, B, Cd, Co, Cr, Cu, Hg, Mo, Pb, Se, and Zn in the sediments were measured using ICP-MS (Inductively Coupled Plasma-Mass Spectrometer). Nature of sediments and heavy metals distribution reflect marked changes in lithology, biological activities in Tarut bay. Very high arsenic concentrations were reported in all studied locations from Tarut Island. The concentrations of Mercury are generally high comparing to the reported values from the Gulf of Oman, Red Sea. The concentrations of As and Hg exceeded the wet threshold safety values (MEC, PEC) indicating possible As and Hg contamination. Dredging and land filling, sewage, and oil pollution are the most important sources of pollution in the study area

  11. Concentrations of Mn and Fe in the Sediment Cores of Sarawak and Sabah Coastal Waters

    International Nuclear Information System (INIS)

    Zal Uyun Wan Mahmood; Zaharudin Ahmad; Che Abdul Rahim Mohamed

    2010-01-01

    Sediment cores were taken at eight stations along Sarawak and Sabah coastal waters using a gravity box corer on July 2004. The sediment cores were cut into 2 cm interval for measurement of Mn and Fe concentration using the Inductive Couple Plasma-Mass Spectrometer (ICP-MS). Overall, the sediment cores contained much mud which include a mixture of silt (46 - 67 %) and clay (18 - 53 %) compared to sand (0.4 - 16 %). The concentrations of Mn and Fe were in the range of 154 - 366 μg/ g and 0.9 - 3.4 %, respectively. The variation was studied by ANOVA, which showed a significant difference (p = 0.000) for both of Mn and Fe concentrations at all sampling stations. In those ranges, Fe concentration was higher compared to Mn. It is believed that dissolving and diluting process influenced the concentration of Mn in the water column and sediment. Fe showed a significant correlation (r > 0.5, p geo < 1 and classification 0 - 1. (author)

  12. Trace element fluxes in sediments of an environmentally impacted river from a coastal zone of Brazil.

    Science.gov (United States)

    da Silva, Yuri Jacques Agra Bezerra; Cantalice, José Ramon Barros; Singh, Vijay P; do Nascimento, Clístenes Williams Araújo; Piscoya, Victor Casimiro; Guerra, Sérgio M S

    2015-10-01

    Data regarding trace element concentrations and fluxes in suspended sediments and bedload are scarce. To fill this gap and meet the international need to include polluted rivers in future world estimation of trace element fluxes, this study aimed to determine the trace element fluxes in suspended sediment and bedload of an environmentally impacted river in Brazil. Water, suspended sediment, and bedload from both the upstream and the downstream cross sections were collected. To collect both the suspended sediment and water samples, we used the US DH-48. Bedload measurements were carried out using the US BLH 84 sampler. Concentrations of Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were determined by inductively coupled plasma (ICP-OES). As and Hg were determined by an atomic absorption spectrophotometer (AA-FIAS). The suspended sediments contributed more than 99 % of the trace element flux. By far Pb and to a less extent Zn at the downstream site represents major concerns. The yields of Pb and Zn in suspended sediments were 4.20 and 2.93 kg km(2) year(-1), respectively. These yields were higher than the values reported for Pb and Zn for Tuul River (highly impacted by mining activities), 1.60 and 1.30 kg km(2) year(-1), respectively, as well as the Pb yield (suspended + dissolved) to the sea of some Mediterranean rivers equal to 3.4 kg km(2) year(-1). Therefore, the highest flux and yield of Pb and Zn in Ipojuca River highlighted the importance to include medium and small rivers-often overlooked in global and regional studies-in the future estimation of world trace element fluxes in order to protect estuaries and coastal zones.

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

    Science.gov (United States)

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

    2016-02-01

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

  14. Sediment Resuspension and Transport During Bora in the Western Adriatic Coastal Current

    Science.gov (United States)

    Mullenbach, B. L.; Geyer, W. R.; Sherwood, C. R.

    2004-12-01

    The Western Adriatic Coastal Current (WACC) is an important agent for along-shelf transport of sediment and fresh water in the western Adriatic Sea. The WACC is driven by a combination of buoyancy forcing from the Po River (northern Adriatic) and wind forcing from northeasterly Bora winds. The large seasonal pulse of freshwater (during the winter) from the Po River influences WACC strength; however, preliminary results from current measurements and model runs indicate that the WACC responds quickly and strongly to Bora wind events, with a strengthening of the current moving southward. Along-margin sediment transport to the south is significantly increased as a result of Bora wind events, presumably because of enhanced wave resuspension and WACC velocity. Elevated sediment fluxes have been observed in both the upper water column (i.e., core of the WACC) and bottom boundary layer (BBL) during these events, which suggests that wind-driven currents may be coupled with the near-bottom transport. This study addresses the interaction of the WACC with the BBL and the impact of this interaction on sediment transport in the western Adriatic. Two benthic tripods were deployed from November 2002 to June 2003 on an across-shelf transect near the Chienti River (at 10 and 20-m water depth), in the region where WACC begins to intensify (200 km south of Po River). Continuous measurements of suspended sediment concentration and current velocity were recorded in the upper-water column and BBL to document sediment transport events. A time series of sediment fluxes and shear velocities (from currents only, u*c; from waves and currents, u*wc) were calculated from these data. Results show that suspended sediment concentrations near the seabed (few cmab) during Bora wind events are strongly correlated with u*wc, which supports a previous hypothesis that wave resuspension (rather than direct fluvial input) is responsible for much of the suspended sediment available for transport southward

  15. Contrasting landscape influences on sediment supply and stream restoration priorities in northern Fennoscandia (Sweden and Finland) and coastal British Columbia.

    Science.gov (United States)

    Rosenfeld, Jordan; Hogan, Daniel; Palm, Daniel; Lundquist, Hans; Nilsson, Christer; Beechie, Timothy J

    2011-01-01

    Sediment size and supply exert a dominant control on channel structure. We review the role of sediment supply in channel structure, and how regional differences in sediment supply and land use affect stream restoration priorities. We show how stream restoration goals are best understood within a common fluvial geomorphology framework defined by sediment supply, storage, and transport. Land-use impacts in geologically young landscapes with high sediment yields (e.g., coastal British Columbia) typically result in loss of in-stream wood and accelerated sediment inputs from bank erosion, logging roads, hillslopes and gullies. In contrast, northern Sweden and Finland are landscapes with naturally low sediment yields caused by low relief, resistant bedrock, and abundant mainstem lakes that act as sediment traps. Land-use impacts involved extensive channel narrowing, removal of obstructions, and bank armouring with boulders to facilitate timber floating, thereby reducing sediment supply from bank erosion while increasing export through higher channel velocities. These contrasting land-use impacts have pushed stream channels in opposite directions (aggradation versus degradation) within a phase-space defined by sediment transport and supply. Restoration in coastal British Columbia has focused on reducing sediment supply (through bank and hillslope stabilization) and restoring wood inputs. In contrast, restoration in northern Fennoscandia (Sweden and Finland) has focused on channel widening and removal of bank-armouring boulders to increase sediment supply and retention. These contrasting restoration priorities illustrate the consequences of divergent regional land-use impacts on sediment supply, and the utility of planning restoration activities within a mechanistic sediment supply-transport framework.

  16. Coastal Morphology and Coastal Protection

    NARCIS (Netherlands)

    Van de Graaff, J.

    2009-01-01

    Lecture notes ct5309. Tides, currents and water; coastal problems; sediment transport processes; coastal transport modes; longshore transport; cross-shore transport; fundamentals of mud; channels and trenches; coastal protection; application of structures; application of nourishments.

  17. Coastal currents and mass transport of surface sediments over the shelf regions of Monterey Bay, California

    Science.gov (United States)

    Wolf, S.C.

    1970-01-01

    In Monterey Bay, the highest concentrations of medium and fine sands occur nearshore between ten and thirty fathoms. Silt and clay accumulate in greater depths. Contours of median diameter roughly parallel the isobaths. Fine-grained materials are supplied to the bay region from erosion of cliffs which partly surround Monterey Bay, from sediment laden river discharge, and from continual reworking of widespread Pleistocene and Recent sea floor sediments. These sediments in turn are picked up by coastal currents and distributed over the shelf regions by present day current regimes. Studies of bottom currents over the shelf regions and in Monterey Canyon have revealed patterns which vary with seasonal changes. Current patterns during August and September exhibit remarkable symmetry about the axis of Monterey Submarine Canyon. Central Shelf currents north and south of Monterey Canyon flowed northwest at an average rate of 0.2 knots and south at 0.3 knots respectively. On the North Shelf between January and March currents flowed east to southeast at 0.3-0.5 knots with mirror image patterns above the South Shelf during the same period. Irregular current flow in the canyon indicates a complex current structure with frequent shifts in counterclockwise and clockwise direction over very short periods of time. Bottom topography of the canyon complex often causes localization of canyon currents. One particular observation at a depth of 51 fathoms indicated up-canyon flow at a rate of 0.2 knots. Most of the observed currents are related to seasonal variations, upwelling, ocean swell patterns, and to changes in the California and Davidson currents. Changes in current regimes are reflected in the patterns of sediment distribution and transport. Sediment transport is chiefly parallel to the isobaths, particularly on the North and South Shelf regions. Complex dispersal patterns are observed near Monterey Canyon and Moss Landing Harbor jetties. Longshore currents move sediments

  18. Land-based sources of marine pollution: Pesticides, PAHs and phthalates in coastal stream water, and heavy metals in coastal stream sediments in American Samoa.

    Science.gov (United States)

    Polidoro, Beth A; Comeros-Raynal, Mia T; Cahill, Thomas; Clement, Cassandra

    2017-03-15

    The island nations and territories of the South Pacific are facing a number of pressing environmental concerns, including solid waste management and coastal pollution. Here we provide baseline information on the presence and concentration of heavy metals and selected organic contaminants (pesticides, PAHs, phthalates) in 7 coastal streams and in surface waters adjacent to the Futiga landfill in American Samoa. All sampled stream sediments contained high concentrations of lead, and some of mercury. Several coastal stream waters showed relatively high concentrations of diethyl phthalate and of organophosphate pesticides, above chronic toxicity values for fish and other aquatic organisms. Parathion, which has been banned by the US Environmental Protection Agency since 2006, was detected in several stream sites. Increased monitoring and initiatives to limit non-point source land-based pollution will greatly improve the state of freshwater and coastal resources, as well as reduce risks to human health in American Samoa. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Numerical Modeling of Coastal Inundation and Sedimentation by Storm Surge, Tides, and Waves at Norfolk, Virginia, USA

    Science.gov (United States)

    2012-07-01

    hurricanes (tropical) with a 50-year and a 100-year return period, and one winter storm ( extratropical ) occurred in October 1982. There are a total of 15...under the 0-m and 2-m SLR scenarios, respectively. • Tropical and extratropical storms induce extensive coastal inundation around the military...1 NUMERICAL MODELING OF COASTAL INUNDATION AND SEDIMENTATION BY STORM SURGE, TIDES, AND WAVES AT NORFOLK, VIRGINIA, USA Honghai Li 1 , Lihwa Lin 1

  20. Dinosaur tracks in Lower Jurassic coastal plain sediments (Sose Bugt Member, Rønne Formation) on Bornholm, Denmark

    DEFF Research Database (Denmark)

    Clemmensen, Lars B; Milàn, Jesper; Pedersen, Gunver K

    2014-01-01

    Fluvial palaeochannels of coastal plain sediments of the Lower Jurassic Sose Bugt Member of the Rønne Formation exposed in the coastal cliffs at Sose Bugt, Bornholm, contain abundant dinosaur or other large vertebrate tracks in the form of deformation structures exposed in vertical section...... track. Contemporary Upper Triassic – Lower Jurassic strata from southern Sweden and Poland contain a diverse track fauna, supporting our interpretation. This is the earliest evidence of dinosaur activity in Denmark....

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

    Science.gov (United States)

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

    2013-01-01

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

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

    Science.gov (United States)

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

    2015-12-01

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

  3. eDNA-based bioassessment of coastal sediments impacted by an oil spill.

    Science.gov (United States)

    Xie, Yuwei; Zhang, Xiaowei; Yang, Jianghua; Kim, Seonjin; Hong, Seongjin; Giesy, John P; Yim, Un Hyuk; Shim, Won Joon; Yu, Hongxia; Khim, Jong Seong

    2018-07-01

    Oil spills offshore can cause long-term ecological effects on coastal marine ecosystems. Despite their important ecological roles in the cycling of energy and nutrients in food webs, effects on bacteria, protists or arthropods are often neglected. Environmental DNA (eDNA) metabarcoding was applied to characterize changes in the structure of micro- and macro-biota communities of surface sediments over a 7-year period since the occurrence of Hebei Spirit oil spill on December 7, 2007. Alterations in diversities and structures of micro- and macro-biota were observed in the contaminated area where concentrations of polycyclic aromatic hydrocarbons were greater. Successions of bacterial, protists and metazoan communities revealed long-term ecological effects of residual oil. Residual oil dominated the largest cluster of the community-environment association network. Presence of bacterial families (Aerococcaceae and Carnobacteriaceae) and the protozoan family (Platyophryidae) might have conferred sensitivity of communities to oil pollution. Hydrocarbon-degrading bacterial families (Anaerolinaceae, Desulfobacteraceae, Helicobacteraceae and Piscirickettsiaceae) and algal family (Araphid pennate) were resistant to adverse effects of spilt oil. The protistan family (Subulatomonas) and arthropod families (Folsomia, Sarcophagidae Opomyzoidea, and Anomura) appeared to be positively associated with residual oil pollution. eDNA metabarcoding can provide a powerful tool for assessing effects of anthropogenic pollution, such as oil spills on sediment communities and its long-term trends in coastal marine environments. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Sediment transport in the San Francisco Bay Coastal System: An overview

    Science.gov (United States)

    Barnard, Patrick L.; Schoellhamer, David H.; Jaffe, Bruce E.; Lester J. McKee,

    2013-01-01

    The papers in this special issue feature state-of-the-art approaches to understanding the physical processes related to sediment transport and geomorphology of complex coastal-estuarine systems. Here we focus on the San Francisco Bay Coastal System, extending from the lower San Joaquin-Sacramento Delta, through the Bay, and along the adjacent outer Pacific Coast. San Francisco Bay is an urbanized estuary that is impacted by numerous anthropogenic activities common to many large estuaries, including a mining legacy, channel dredging, aggregate mining, reservoirs, freshwater diversion, watershed modifications, urban run-off, ship traffic, exotic species introductions, land reclamation, and wetland restoration. The Golden Gate strait is the sole inlet connecting the Bay to the Pacific Ocean, and serves as the conduit for a tidal flow of ~ 8 x 109 m3/day, in addition to the transport of mud, sand, biogenic material, nutrients, and pollutants. Despite this physical, biological and chemical connection, resource management and prior research have often treated the Delta, Bay and adjacent ocean as separate entities, compartmentalized by artificial geographic or political boundaries. The body of work herein presents a comprehensive analysis of system-wide behavior, extending a rich heritage of sediment transport research that dates back to the groundbreaking hydraulic mining-impact research of G.K. Gilbert in the early 20th century.

  5. Renewed soil erosion and remobilisation of radioactive sediment in Fukushima coastal rivers after the 2013 typhoons.

    Science.gov (United States)

    Evrard, Olivier; Chartin, Caroline; Onda, Yuichi; Lepage, Hugo; Cerdan, Olivier; Lefèvre, Irène; Ayrault, Sophie

    2014-04-03

    Summer typhoons and spring snowmelt led to the riverine spread of continental Fukushima fallout to the coastal plains of Northeastern Japan and the Pacific Ocean. Four fieldwork campaigns based on measurement of radioactive dose rates in fine riverine sediment that has recently deposited on channel bed-sand were conducted between November 2011 and May 2013 to document the spread of fallout by rivers. After a progressive decrease in the fresh riverine sediment doses rates between 2011 and early spring in 2013, a fifth campaign conducted in November 2013 showed that they started to increase again after the occurrence of violent typhoons. We show that this increase in dose rates was mostly due to remobilization of contaminated material that was temporarily stored in river channels or, more importantly, in dam reservoirs of the region during the typhoons. In addition, supply of particles from freshly eroded soils in autumn 2013 was the most important in areas where decontamination works are under progress. Our results underline the need to monitor the impact of decontamination works and dam releases in the region, as they may provide a continuous source of radioactive contamination to the coastal plains and the Pacific Ocean during the coming years.

  6. Seasonal variation of iron speciation in a pearl-raising bay sediment by Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Kuno, Akihito; Matsuo, Motoyuki; Chiba, Satoshi; Yamagata, Yoichi

    2008-01-01

    Ago Bay in Mie Prefecture, central Japan, is world-famous for the site of Mikimoto pearl culture, but recently the production of pearls has considerably declined. Environmental deterioration of the bay is suspected of having caused the decline. The periodic investigation into iron speciation of the bay sediment by 57 Fe Moessbauer spectroscopy revealed its high pyrite (FeS 2 ) content from the surface to the 20-cm depth. The pyrite in the surface sediment decreased only in spring, three months after the dissolved oxygen in the bottom water was at maximum. Such oxygen-consuming material as pyrite accumulated through long-term biotic activity is a most-likely explanation for the prolonged environmental deterioration of the bay, which appears in the high chemical oxygen demand (COD) of the sediment. (author)

  7. Changes of freshwater-lens thickness in basaltic island aquifers overlain by thick coastal sediments

    Science.gov (United States)

    Rotzoll, Kolja; Oki, Delwyn S.; El-Kadi, Aly I.

    2010-01-01

    Freshwater-lens thickness and long-term changes in freshwater volume in coastal aquifers are commonly assessed through repeated measurement of salinity profiles from monitor wells that penetrate into underlying salt water. In Hawaii, the thickest measured freshwater lens is currently 262 m in dike-free, volcanic-rock aquifers that are overlain by thick coastal sediments. The midpoint depth (depth where salinity is 50% salt water) between freshwater and salt water can serve as an indicator for freshwater thickness. Most measured midpoints have risen over the past 40 years, indicating a shrinking lens. The mean rate of rise of the midpoint from 1999–2009 varied locally, with faster rates in highly developed areas (1.0 m/year) and slower rates in less developed areas (0.5 m/year). The thinning of the freshwater lenses is the result of long-term groundwater withdrawal and reduced recharge. Freshwater/salt-water interface locations predicted from measured water levels and the Ghyben-Herzberg principle may be deeper than measured midpoints during some periods and shallower during other periods, although depths may differ up to 100 m in some cases. Moreover, changes in the midpoint are slower than changes in water level. Thus, water levels may not be a reliable indicator of the amount of freshwater in a coastal aquifer.

  8. Numerical simulation of sediment transport from Ba Lat Mouth and the process of coastal morphology

    International Nuclear Information System (INIS)

    Chung, Dang Huu

    2008-01-01

    This paper presents an application of a 3D numerical model to simulate one vertical layer sediment transport and coastal morphodynamical process for the Hai Hau coastal area located in the north of Vietnam, where a very large amount of suspended sediment is carried into the sea from Ba Lat Mouth every year. Four simulations are based on the real data of waves supplied by the observation station close to Ba Lat Mouth. The conditions of wind and suspended sand concentration at Ba Lat Mouth are basically assumed from practice. The computed results show that the hydrodynamic factors strongly depend on the wind condition and these factors govern the direction and the range of suspended sand transport, especially in the shallow-water region. In the deep-water region this influence is not really clear when the wind force is not strong enough to modify the tidal current. In the area close to Ba Lat Mouth the flow velocity is very large with the maximum flood flow about 2.6 m s −1 and the maximum ebb flow about 1 m s −1 at the mouth, and this is one of the reasons for strong erosion. In the case of tidal flow only, the suspended sand concentration decreases resulting in local deposition. Therefore, the area influenced by suspended transport is small, about 12 km from the mouth. In the condition of wind and waves, the suspended sand transport reaches the end of the computation area within a few days, especially the cases with wind from the north-east-north. Through these simulation results, a common tendency of sediment movement from the north to the south is specified for the Hai Hau coastal area. In addition, the results also show that the coast suffers from strong erosion, especially the region near Ba Lat Mouth. From the simulation results it can be seen that the movement of the Red River sand along the Vietnamese coast is quite possible, which is an answer to a long-standing question. Furthermore, although the suspended sediment concentration is quite large, it is

  9. Relationships between pesticides and organic carbon fractions in sediments of the Danshui River estuary and adjacent coastal areas of Taiwan

    International Nuclear Information System (INIS)

    Hung, C.-C.; Gong, G.-C.; Chen, H.-Y.; Hsieh, H.-L.; Santschi, Peter H.; Wade, Terry L.; Sericano, Jose L.

    2007-01-01

    In order to understand the fate of pesticides in marine environments, concentrations of pesticides and different carbonaceous fractions were determined for surface sediments in the Danshui River and nearby coastal areas of Taiwan. The major compounds detected were tetrachlorobenzene, HCHs, chlordane, aldrin, DDDs, DDEs and DDTs. Total concentrations of pesticides in the sediments ranged from not detectable to 23 ng g -1 , with the maximum value detected near the discharge point of the marine outfall from the Pali sewage treatment plant. These results confirm that pesticides persist in estuarine and nearby coastal environments of the Danshui River well after their ban. Concentrations of total pesticides significantly correlate with concentrations of total organic carbon and black carbon in these sediments, suggesting that total organic carbon and black carbon regulate the distribution of trace organic pollutants in fluvial and coastal marine sediments. - Total organic carbon and black carbon regulate the distribution of trace organic pollutants in sediments of the Danshui River estuary and adjacent coastal areas of Taiwan

  10. Acetate, lactate, propionate, and isobutyrate as electron donors for iron and sulfate reduction in Arctic marine sediments, Svalbard

    DEFF Research Database (Denmark)

    Finke, Niko; Vandieken, Verona; Jørgensen, Bo Barker

    2007-01-01

    The contribution of volatile fatty acids (VFA) as e--donors for anaerobic terminal oxidation of organic carbon through iron and sulfate reduction was studied in Arctic fjord sediment. Dissolved inorganic carbon, Fe2+, VFA concentrations, and sulfate reduction were monitored in slurries from...... by alternative e--donors. The accumulation of VFA in the selenate-inhibited 0-2 cm slurry did not enhance iron reduction, indicating that iron reducers were not limited by VFA availability....

  11. Temperature, productivity and sediment characteristics as drivers of seasonal and spatial variations of dissolved methane in the near-shore coastal areas (Belgian coastal zone, North Sea)

    Science.gov (United States)

    Borges, Alberto V.; Speeckaert, Gaëlle; Champenois, Willy; Scranton, Mary I.; Gypens, Nathalie

    2017-04-01

    The open ocean is a modest source of CH4 to the atmosphere compared to other natural and anthropogenic CH4 emissions. Coastal regions are more intense sources of CH4 to the atmosphere than open oceanic waters, in particular estuarine zones. The CH4 emission to the atmosphere from coastal areas is sustained by riverine inputs and methanogenesis in the sediments due to high organic matter (OM) deposition. Additionally, natural gas seeps are sources of CH4 to bottom waters leading to high dissolved CH4 concentrations in bottom waters (from tenths of nmol L-1 up to several µmol L-1). We report a data set of dissolved CH4 concentrations obtained at nine fixed stations in the Belgian coastal zone (Southern North Sea), during one yearly cycle, with a bi-monthly frequency in spring, and a monthly frequency during the rest of the year. This is a coastal area with multiple possible sources of CH4 such as from rivers and gassy sediments, and where intense phytoplankton blooms are dominated by the high dimethylsulfoniopropionate (DMSP) producing micro-algae Phaeocystis globosa, leading to DMSP and dimethylsulfide (DMS) concentrations. Furthermore, the BCZ is a site of important OM sedimentation and accumulation unlike the rest of the North Sea. Spatial variations of dissolved CH4 concentrations were very marked with a minimum yearly average of 9 nmol L-1 in one of the most off-shore stations and maximum yearly average of 139 nmol L-1 at one of the most near-shore stations. The spatial variations of dissolved CH4 concentrations were related to the organic matter (OM) content of sediments, although the highest concentrations seemed to also be related to inputs of CH4 from gassy sediments associated to submerged peat. In the near-shore stations with fine sand or muddy sediments with a high OM content, the seasonal cycle of dissolved CH4 concentration closely followed the seasonal cycle of water temperature, suggesting the control of methanogenesis by temperature in these OM

  12. Elemental signature of terrigenous sediment runoff as recorded in coastal salt ponds: US Virgin Islands

    International Nuclear Information System (INIS)

    Larson, Rebekka A.; Brooks, Gregg R.; Devine, Barry; Schwing, Patrick T.; Holmes, Charles W.; Jilbert, Tom; Reichart, Gert-Jan

    2015-01-01

    A high-resolution, multi-proxy approach is utilized on mm- to cm-scale laminated coastal salt pond sediments from St. John, U.S. Virgin Islands, to determine: (1) the sedimentological signature of depositional events/processes, (2) link this sedimentological signature with known depositional events/processes in the historical (past ∼100 years) record; and, (3) project back into the recent geologic past (past ∼1400 years) to investigate the natural variability of depositional events/processes. High-resolution, short-lived radioisotope geochronology ("2"1"0Pb, "1"3"7Cs, "7Be) combined with high-resolution elemental scanning techniques (scanning XRF and scanning LA-ICP-MS) allows for the direct comparison of well-preserved salt pond deposits to historical records of depositional events (e.g., runoff/rainfall, tropical cyclones, tsunamis) to identify the sedimentary signature of each type of event. There is a robust sedimentary record of terrigenous sediment runoff linked to the frequency of rainfall events that exceed a threshold of ∼12 mm/day (minimum to mobilize and transport sediment) for study sites. This is manifested in the sedimentary record as increases in terrigenous indicator elements (%Al, %Fe, %Ti, %Si), which agree well with rainfall records over the past ∼50 years. Variability in the sedimentary record over the past ∼100 years reflects decadal-scale fluctuations between periods of increased frequency of rainfall events, and decreased frequency of rainfall events. Dm-scale variability in terrigenous indicator elements over the past ∼1400 years represents the natural system variability on a decadal–centennial scale, and provides a high-resolution, long-term baseline of natural variability of rainfall/runoff events. A period of increased terrigenous sediment delivery during the 1700s and 1800s likely indicates increased erosion in response to anthropogenic activities associated with the island’s plantation era, and perhaps increased

  13. Flocculated meltwater particles control Arctic land-sea fluxes of labile iron

    DEFF Research Database (Denmark)

    Markussen, Thor Nygaard; Elberling, Bo; Winter, Christian

    2016-01-01

    Glacial meltwater systems supply the Arctic coastal ocean with large volumes of sediment and potentially bioavailable forms of iron, nitrogen and carbon. The particulate fraction of this supply is significant but estuarine losses have been thought to limit the iron supply from land. Here, our...... the influence of terrestrial hotspots on the nutrient and solute cycles in Arctic coastal waters....

  14. Concentrations and annual fluxes of sediment-associated chemical constituents from conterminous US coastal rivers using bed sediment data

    Science.gov (United States)

    Horowitz, Arthur J.; Stephens, Verlin C.; Elrick, Kent A.; Smith, James J.

    2012-01-01

    Coastal rivers represent a significant pathway for the delivery of natural and anthropogenic sediment-associated chemical constituents to the Atlantic, Pacific and Gulf of Mexico coasts of the conterminous USA. This study entails an accounting segment using published average annual suspended sediment fluxes with published sediment-associated chemical constituent concentrations for (1) baseline, (2) land-use distributions, (3) population density, and (4) worldwide means to estimate concentrations/annual fluxes for trace/major elements and total phosphorus, total organic and inorganic carbon, total nitrogen, and sulphur, for 131 coastal river basins. In addition, it entails a sampling and subsequent chemical analysis segment that provides a level of ‘ground truth’ for the calculated values, as well as generating baselines for sediment-associated concentrations/fluxes against which future changes can be evaluated. Currently, between 260 and 270 Mt of suspended sediment are discharged annually from the conterminous USA; about 69% is discharged from Gulf rivers (n = 36), about 24% from Pacific rivers (n = 42), and about 7% from Atlantic rivers (n = 54). Elevated sediment-associated chemical concentrations relative to baseline levels occur in the reverse order of sediment discharges:Atlantic rivers (49%)>Pacific rivers (40%)>Gulf rivers (23%). Elevated trace element concentrations (e.g. Cu, Hg, Pb, Zn) frequently occur in association with present/former industrial areas and/or urban centres, particularly along the northeast Atlantic coast. Elevated carbon and nutrient concentrations occur along both the Atlantic and Gulf coasts but are dominated by rivers in the urban northeast and by southeastern and Gulf coast (Florida) ‘blackwater’ streams. Elevated Ca, Mg, K, and Na distributions tend to reflect local petrology, whereas elevated Ti, S, Fe, and Al concentrations are ubiquitous, possibly because they have substantial natural as well as anthropogenic sources

  15. Discriminating sediment and clear water over coastal water using GD technique

    Directory of Open Access Journals (Sweden)

    Amin Abd Rahman Mat

    2017-03-01

    Full Text Available Currently two algorithms are being used routinely by the MODIS Atmosphere and Ocean Team in order to distinguish sediment influence and clear water pixels over turbid water area. These two algorithms require complicated computational analyses. In this paper, a simple algorithm based on empirical technique to detect the sediment-influenced pixels over coastal waters is proposed as an alternative to these two algorithms. This study used apparent reflectance acquired from MODIS L1B product. This algorithm is based on the gradient difference of the line connecting the 0.47- and 1.24-μm channels and 0.47- and 0.66-μm channels of a log-log graph of the apparent reflectance values against MODIS wavelengths. Over clear-water areas (deep blue sea, the 0.47-, 0.66- and 1.24-μm channels fitted very well in line with correlation R > 0.99. Over turbid waters, a substantial increase of 0.66 μm in the reflectance leads to a low correlation value. By computing the difference between the gradient of the line connecting 0.47 and 0.66 μm and the gradient of the line connecting 0.47 and 1.24 μm, the threshold to discriminate turbid and shallow coastal waters from clear-water pixels can be obtained. If the gradient difference is greater than 0, the pixels were then marked as sediment-influenced pixels. This proposed algorithm works well for MODIS Terra and Aqua sensor. The comparison of this algorithm with an established algorithm also showed a good agreement.

  16. Distribution of rare earth elements in the estuarine and coastal sediments of the Daliao River System, China

    International Nuclear Information System (INIS)

    Chunye Lin; Shaoqing Liu; Mengchang He; Ruiping Li

    2013-01-01

    The Daliao River System (DRS) estuary in Liaodong Bay features a highly industrial, urbanized, and agricultural catchment. The objective of this study was to determine the content, behavior, and distribution of the rare earth elements (REEs) in the estuarine and coastal sediments. To this end, 35 sediment samples were collected from the estuarine and coastal area and analyzed for REEs, Fe, Al, and Mn. The mean concentrations in mg kg -1 of the sediments were 33.4 (La), 64.1 (Ce), 7.9 (Pr), 29.0 (Nd), 5.4 (Sm), 1.2 (Eu), 4.2 (Gd), 0.78 (Tb), 4.0 (Dy), 0.84 (Ho), 2.3 (Er), 0.40 (Tm), 2.3 (Yb), and 0.37 (Lu). The REE concentrations in the sediments were significantly correlated with one another (r 2 = 0.959-0.988) and the concentrations of Fe, Al, and Mn (r 2 = 0.768-0.870). The total concentration ΣREE ranged from 73.5 to 203.5 mg kg -1 , with an average of 156.0 mg kg -1 being observed, and generally higher in the estuarine sediments than in the coastal sediments, most likely due to the salt-induced coagulation of river colloids and subsequently their accumulation at the estuarine bottom. The ratio of light REEs (ΣLREE) to heavy REEs (ΣHREE) was 9.4. Chondrite-normalized REE distributions were observed to be similar for the estuarine and coastal sediments, riverine suspended particles, and watershed soils of the DRS with higher LRRE enrichment than HREE and greater Eu depletion than Ce depletion. These results demonstrate that neither geochemical processes that carry soils to estuarine sediments nor long-term industrial and agricultural activities alter the distribution or fractionation of the REEs in the study area. (author)

  17. Impact of Seasonal Hypoxia on Activity and Community Structure of Chemolithoautotrophic Bacteria in a Coastal Sediment.

    Science.gov (United States)

    Lipsewers, Yvonne A; Vasquez-Cardenas, Diana; Seitaj, Dorina; Schauer, Regina; Hidalgo-Martinez, Silvia; Sinninghe Damsté, Jaap S; Meysman, Filip J R; Villanueva, Laura; Boschker, Henricus T S

    2017-05-15

    Seasonal hypoxia in coastal systems drastically changes the availability of electron acceptors in bottom water, which alters the sedimentary reoxidation of reduced compounds. However, the effect of seasonal hypoxia on the chemolithoautotrophic community that catalyzes these reoxidation reactions is rarely studied. Here, we examine the changes in activity and structure of the sedimentary chemolithoautotrophic bacterial community of a seasonally hypoxic saline basin under oxic (spring) and hypoxic (summer) conditions. Combined 16S rRNA gene amplicon sequencing and analysis of phospholipid-derived fatty acids indicated a major temporal shift in community structure. Aerobic sulfur-oxidizing Gammaproteobacteria ( Thiotrichales ) and Epsilonproteobacteria ( Campylobacterales ) were prevalent during spring, whereas Deltaproteobacteria ( Desulfobacterales ) related to sulfate-reducing bacteria prevailed during summer hypoxia. Chemolithoautotrophy rates in the surface sediment were three times higher in spring than in summer. The depth distribution of chemolithoautotrophy was linked to the distinct sulfur oxidation mechanisms identified through microsensor profiling, i.e., canonical sulfur oxidation, electrogenic sulfur oxidation by cable bacteria, and sulfide oxidation coupled to nitrate reduction by Beggiatoaceae The metabolic diversity of the sulfur-oxidizing bacterial community suggests a complex niche partitioning within the sediment, probably driven by the availability of reduced sulfur compounds (H 2 S, S 0 , and S 2 O 3 2- ) and electron acceptors (O 2 and NO 3 - ) regulated by seasonal hypoxia. IMPORTANCE Chemolithoautotrophic microbes in the seafloor are dependent on electron acceptors, like oxygen and nitrate, that diffuse from the overlying water. Seasonal hypoxia, however, drastically changes the availability of these electron acceptors in the bottom water; hence, one expects a strong impact of seasonal hypoxia on sedimentary chemolithoautotrophy. A

  18. The scavenging of silver by manganese and iron oxides in stream sediments collected from two drainage areas of Colorado

    Science.gov (United States)

    Chao, T.T.; Anderson, B.J.

    1974-01-01

    Stream sediments of two well-weathered and aerated drainage areas of Colorado containing anomalous amounts of silver were allowed to react by shaking with nitric acid of different concentrations (1-10M). Silver, manganese, and iron simultaneously dissolved were determined by atomic absorption. The relationship between silver dissolution and the dissolution of manganese and/or iron was evaluated by linear and multiple regression analyses. The highly significant correlation coefficient (r = 0.913) between silver and manganese dissolution suggests that manganese oxides are the major control on the scavenging of silver in these stream sediments, whereas iron oxides only play a secondary role in this regard. ?? 1974.

  19. Experimental studies on the geochemical behaviour of 54-Mn considering coastal and deep sea sediments

    International Nuclear Information System (INIS)

    Guegueniat, P.; Boust, D.; Dupont, J.P.; Aprosi, G.

    1985-01-01

    In order to study the geochemical behaviour of 54-Mn in the marine environment (Mn/sup 2+/) 200 sediments gathered in deep sea and in coastal waters were contaminated experimentally. To correlate the various results, the oxidation processes occurring with or without sediments should be specified. During this experimental work, the geochemical behaviour of manganese is dealt with using a radioactive tracer (54-Mn) in the divalent state and sediments collected on french littoral (160) in deep sea (30). The latest data published offer an excellent assessment of research findings on manganese in marine and estuary environments and testify to the interest constantly generated by this subject. It is difficult to establish a priori any predictions on the behaviour of manganese based on the properties of a given environment, notably as concerns redox conditions. The oxidation of manganese was found to be governed by a very slow autocatalysis mechanism capable of being concealed by surface catalyses on mineral phases in suspension or oxidation due to bacteria. The residence time in sea water vary considerably depending on the case from a few days to some tens of years

  20. Accumulation of phosphorus in coastal marine sediments: relationship to benthic and diffusive fluxes

    Directory of Open Access Journals (Sweden)

    Rocio Ponce

    2010-11-01

    Full Text Available Sedimentary phosphorus was characterized in sediment cores from 3 coastal ecosystems of the Gulf of Cadiz. High spatial variability was observed in total phosphorus (from 445 to 20291 μg g.sed-1 and in the other phosphorus phases studied. This variability correlates with the proximity of the 10 sampling stations to sources of urban and/or industrial effluent in the zone. The benthic and diffusive fluxes were measured concurrently with sediment collection at these stations. The measured values of benthic fluxes range between –14 and 6 mmol m-2 d-1. Generally, stations that showed increased interstitial phosphate concentrations with increasing depth were characterized by positive values in phosphate benthic fluxes and by high percentages of reactive forms of sedimentary phosphorus. Negative benthic fluxes were associated with stations receiving more anthropogenic matter, which showed progressively decreasing phosphate concentrations in the interstitial water with depth. In these anthropogenic areas, the non-reactive forms of phosphorus (those associated with ferric oxyhydroxide and authigenic carbonate fluorapatite are abundant, and reach values exceeding 75% of total phosphorus in sediment.

  1. Polybrominated diphenyl ethers (PBDEs) in sediments of the coastal East China Sea: Occurrence, distribution and mass inventory

    International Nuclear Information System (INIS)

    Li Yuanyuan; Lin Tian; Chen Yingjun; Hu Limin; Guo Zhigang; Zhang Gan

    2012-01-01

    Polybrominated diphenyl ethers (PBDEs) of sixty-three sediment samples from the coastal East China Sea (ECS), extending ∼1000 km from the Yangtze River Estuary to the south, were measured. The levels of BDE-209 and ∑PBDE 7 (sum of BDE-28, 47, 99, 100, 153, 154, 183) were 0.3–44.6 ng/g (dry weight) and nd-8.0 ng/g, respectively. BDE-209 was the predominant congener, followed by BDE-99/100. This was consistent with the historical and current usage of PBDE mixtures in China. The compositions and distribution of PBDEs suggest that the PBDEs in this area could be mainly from the coastal electronic waste dismantling/recycling and Yangtze River input. The poor correlations between TOC, grain size of sediments with PBDEs imply that the PBDE distribution is more related to their land-based inputs rather than the sediment characters in the area. The coastal ECS is an important sink of PBDEs (7.5 t/yr) in the world. - Highlights: ► First report on the levels, distribution and inventory of PBDEs in the inner shelf of the ECS. ► PBDEs were mainly from the coastal electronic waste dismantling/recycling and Yangtze River. ► PBDE distribution was related to the land-based inputs rather than the sediment characters. ► The coastal East China Sea is an important sink of the PBDEs in the world. - The levels, distribution, potential sources and mass inventory of PBDEs in sediments of the coastal East China Sea were revealed.

  2. Evidence for the Occurrence of Microbial Iron Reduction in Bulk Aerobic Unsaturated Sediments

    Science.gov (United States)

    Cooper, D. C.; Kukkadapu, R. K.; Smith, W. A.; Fox, D. T.; Plummer, M. A.; Hull, L. C.

    2003-12-01

    Radionuclide transport experiments conducted in a large, meso-scale column reactor (MSCR, 10 ft high x 3 ft dia) operated under unsaturated flow conditions with simulated rainwater influent provide evidence that microbial iron reduction can occur in bulk-aerobic vadose zone systems with a low organic carbon content (~0.5 wt%). Soil gas analyses indicate that CO2 varied between ~0.1% of soil gas (top) and 12% to 18% of soil gas (bottom). O2 varied inversely with CO2, and the ratio of (CO2 produced) / (O2 consumed) was 0.8 +/- 0.1. NO3- was present at high concentrations, and originated from soluble NO3- salts present in the packing material. Ammonia was present at low levels, and limited NO2- production was observed. There was no increase in aqueous iron, and methane and sulfide were not produced. M\\H{o}ssbauer analyses of sediment iron mineralogy indicate that the sedimentary iron in the packing material is 63% illite Fe(III), 16% illite Fe(II), 13% hematite, and 8% poorly-crystalline/small-particulate (pc/sp) iron oxide. Sediments collected from the lower portion of the column (5.5 fbs, feet below surface) still contain illite and hematite, but have lost the pc/sp iron oxide component. The Fe(III)/Fe(II) ratio of the illite appears to be unchanged at this depth. Analyses of sediment extractable DNA and cell number indicate that bacterial abundances increase from the surface to 0.5 fbs, and then remain constant with depth. Initial results from DGGE and 16s rDNA clone libraries indicate that microbial community structure alters with increasing depth, decreasing O2 content, and loss of pc/sp iron oxides. These data indicate a predominance of Clostridium at the column top, with Bacillus, Desulfobacterium, and Pseudomonas also providing a significant contribution. At 0.5 fbs, Clostridium represents a larger fraction of the total community with Desulfobacterium present as the second most abundant component. By 5.5 fbs, Clostridium is a minor component and the community

  3. 3D Airflow patterns over coastal foredunes: implications for aeolian sediment transport

    Science.gov (United States)

    Jackson, Derek W. T.; Cooper, Andrew G.; Baas, Andreas C. W.; Lynch, Kevin; Beyers, Meiring

    2010-05-01

    A fundamental criterion for the development of coastal sand dunes is usually highlighted as a significant onshore wind component of the local wind field. The presence of large sand dune systems on coasts where the predominant wind blows offshore is therefore difficult to explain and usually they are attributed to the past occurrence of onshore winds and, by implication, subsequent changes in climate. Recent studies have shown that offshore winds can be deflected or 'steered' by existing dunes so that their direction changes. This can occur to such an extent that a process known as 'flow reversal' can arise, whereby the initially offshore wind actually flows onshore at the beach. This process is important because it can cause sand to be blown from the beach and into the dunes, causing them to grow. This may be central in explaining the presence of extensive dunes on coasts where the dominant wind is offshore, but is also important in how dunes recover after periods of wave erosion during storms. Offshore winds have traditionally been excluded from sediment budget calculations for coastal dunes, but when they do transport sand onshore, this may have been an important oversight leading to significant underestimates of the volume of sand being transported by wind. This work investigates the controls on the processes and the mechanisms involved in deformation of the flow and resulting sediment transport at coastal foredunes in Northern Ireland. We use a combination of field measurement of wind and sediment transport coupled with state-of-the-art aerodynamic modelling using computational fluid dynamics (CFD) and 3-D sonic anemometry. Our working hypothesis is that offshore winds contribute substantially to foredune behaviour on leeside coasts. Preliminary results show strong reverse flow eddies in the seaward side of the foredunes during offshore wind events. These secondary flow reversals have been above velocity threshold and are transport capable. Using CFD modelling

  4. Iron Ore Industry Emissions as a Potential Ecological Risk Factor for Tropical Coastal Vegetation

    Science.gov (United States)

    Kuki, Kacilda N.; Oliva, Marco A.; Pereira, Eduardo G.

    2008-07-01

    In the coastal zone of the Espírito Santo state, Brazil, fragments of restinga, which form a natural ecosystem, share their space with an increasing number of iron ore industries. The iron ore dust and SO2 originating from the industry processing activities can interfere with the vegetation of the adjacent ecosystems at various levels. This study was undertaken in order to evaluate the effects of industry emissions on representative members of the restinga flora, by measuring physiological and phenological parameters. Foliar samples of Ipomoea pes caprae, Canavalia rosea, Sophora tomentosa, and Schinus terebinthifolius were collected at three increasing distances from an ore industry (1.0, 5.0, and 15.0 km), and were assessed for their dust deposition, chlorophyll, and Fe content. Phenological monitoring was focused on the formation of shoots, flowers, and fruits and was also performed throughout the course of a year. The results showed that the edaphic characteristics and the mineral constitutions of the plants were affected by industry emissions. In addition, the chlorophyll content of the four species increased with proximity to the industry. Phenological data revealed that the reproductive effort, as measured by fruit production, was affected by emissions and S. tomentosa was the most affected species. The use of an integrative approach that combines biochemical and ecological data indicates that the restinga flora is under stress due to industry emissions, which on a long-term basis may put the ecosystem at risk.

  5. The Concentration Levels Of Some Isotopic Radionuclides In The Coastal Sediments Of The Red Sea, Egypt

    International Nuclear Information System (INIS)

    EL SAHARTY, A.A.; DAR, M.A.

    2010-01-01

    The radionuclide activities of 238 U, 232 Th, 40 K and 137 Cs were measured using high resolution gamma spectrometry system. The total organic matter (TOM) and carbonate contents were also measured in the surface sediments of three valleys downstream at the southern Egyptian Red Sea coast. These localities are characterized by the presence of mangrove swamps with dense aerobic roots that provide calm conditions for particulate and fine sediments settlement. 238 U and 232 Th recorded almost equal activity values in the studied localities and their occurrence in the localities indicated that the metal accumulation are due to the complex and multiple processes that characterize the mangrove environments including accumulation in particulate form with the fine sediments, absorption on iron and manganese oxides and hydroxides from the sea water, incorporation inside the carbonate frameworks and as detrital phase. 40 K showed obvious radioactivity in the three localities indicating the presence of terrestrial radionuclide. 137 Cs concentrations were not evident in the studied localities which may indicate non-significant artificial source of radionuclide activity.

  6. Can hydrocarbons in coastal sediments be related to terrestrial flux? A case study of Godavari river discharge (Bay of Bengal)

    Digital Repository Service at National Institute of Oceanography (India)

    Rayaprolu, K.; GopalaKrishna, V.V.J.; Naik, B.G.; Mahalakshmi, G.; Rengarajan, R.; Mazumdar, A; Sarma, N.S.

    A sediment core aged ~250 years and deposition rate of ~2.4 mm yr-1 raised from the coastal region receiving inputs from the Godavari river was examined for n-alkanes The carbon preference index (CPI) of shortchain hydrocarbons (SHC...

  7. Sediment Radiochronology Using Coastal 210Pb: Model, Validation and Applications (Spanish Edition)

    International Nuclear Information System (INIS)

    Sanchez-Cabeza, Joan-Albert; Diaz-Asencio, Misael; Ruiz-Fernandez, Ana Carolina

    2012-01-01

    techniques in support of integrated coastal zone. This project is aligned with the objectives of the IAEA in the environment, including 'facilitating the sustainable use of natural resources where isotopes can improve understanding of natural systems that allow, for example, prediction of future global trends from the past and overall assessment of resources'. The project involves Colombia, Costa Rica, Cuba, Guatemala, Haiti, Honduras, Jamaica, Mexico, Nicaragua, Panama, Dominican Republic and Venezuela, with the support of the Centre for Energy, Environment and Technology (CIEMAT, Spain), the Institute Research for Development (IRD, France) and in collaboration with the Regional Coordinating Unit of the Caribbean of the United Nations Program for the Environment (UNEP-CAR/RCU). It is expected that the project results will improve the commitment of Member States and regional organizations in activities to protect the environment now and in the future. Through the regional laboratory training and a better understanding of coastal ecosystems from baseline studies and historical reconstruction of pollution levels, a strong network of laboratories with improved capabilities will be able to continue to contribute to the sustainable management of Caribbean Sea. Methodologies are being developed for monitoring and management. The results will be disseminated to the scientific community, policy makers and society, in addition to international organizations such as UNEP and the Association of Caribbean States. The objective of the results is to support integrated management of the coastal zone. One of the main methodologies of this project is the use of coastal sediments as records of environmental change, including pollution. Since most of the changes have occurred in the region during the twentieth century, the best chronology is provided by 210 Pb, a natural radioactive element with a half-life of about 20 years, allowing sediments dating to about 100 years of seniority. Although

  8. Distribution of biologic, anthropogenic, and volcanic constituents as a proxy for sediment transport in the San Francisco Bay Coastal System

    Science.gov (United States)

    McGann, Mary; Erikson, Li H.; Wan, Elmira; Powell, Charles; Maddocks, Rosalie F.; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.

    2013-01-01

    Although conventional sediment parameters (mean grain size, sorting, and skewness) and provenance have typically been used to infer sediment transport pathways, most freshwater, brackish, and marine environments are also characterized by abundant sediment constituents of biological, and possibly anthropogenic and volcanic, origin that can provide additional insight into local sedimentary processes. The biota will be spatially distributed according to its response to environmental parameters such as water temperature, salinity, dissolved oxygen, organic carbon content, grain size, and intensity of currents and tidal flow, whereas the presence of anthropogenic and volcanic constituents will reflect proximity to source areas and whether they are fluvially- or aerially-transported. Because each of these constituents have a unique environmental signature, they are a more precise proxy for that source area than the conventional sedimentary process indicators. This San Francisco Bay Coastal System study demonstrates that by applying a multi-proxy approach, the primary sites of sediment transport can be identified. Many of these sites are far from where the constituents originated, showing that sediment transport is widespread in the region. Although not often used, identifying and interpreting the distribution of naturally-occurring and allochthonous biologic, anthropogenic, and volcanic sediment constituents is a powerful tool to aid in the investigation of sediment transport pathways in other coastal systems.

  9. Concentrations and sources of polycyclic aromatic hydrocarbons in surface coastal sediments of the northern Gulf of Mexico

    Science.gov (United States)

    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

  10. Palynomorphs in Holocene sediments from a paleolagoon in the coastal plain of extreme southern Brazil

    Directory of Open Access Journals (Sweden)

    Ebráilon Masetto

    2014-06-01

    Full Text Available This paper presents the results of a qualitative palynological analysis of a 140 cm-thick section of Holocene sediments from a paleolagoon, representing the last 2600 years, taken from an outcrop at Hermenegildo Beach (33º42'S; 53º18'W, located in the municipality of Santa Vitória do Palmar, in the state of Rio Grande do Sul, Brazil. Samples were treated with hydrochloric acid, hydrofluoric acid and potassium hydroxide, after which they were subjected to acetolysis and mounted on glycerin-coated slides for light microscopy analysis. Among the 48 palynomorphs identified were 25 fungi, eight algae, three bryophytes, and 12 pteridophytes. Brief descriptions and illustrations of each palynomorph are presented, together with ecological data from the organism of origin when possible. Our findings will serve as reference material for paleoenvironmental studies in the coastal plain of southern Brazil.

  11. PIXE as a monitoring method on the behavior of elements in coastal sediments

    International Nuclear Information System (INIS)

    Matsuda, Y.; Ishiyama, T.; Ito, N.; Kiyoda, S.

    1993-01-01

    The chemical extraction + PIXE + NAA proposed in the previous paper as a monitoring method of the elemental behavior in the coastal sediments is appeared as a very useful technique in view of giving information on detail adsorption/ desorption behavior of transition metal ions. The ratios of reversible adsorption amounts to total adsorption with Mn and Co were comparatively high as 0.37 and 0.13, respectively. On the other hand, the ratios with Fe and Zn were very low as 0.01. Any eluting rates of Mn, Fe, Co and Zn were considerably greater with 0.01 M EDTA·2Na than with 0.2 M ammonium oxalate, which reflect the sizes of the stability constants of chelates with possible forms at extraction. (1 tab.)

  12. Analysis of Multi Temporal Satellite Imagery for Total Suspended Sediments in a Wave-Active Coastal Area-Gaza Strip Coastal Water, Palestine

    Directory of Open Access Journals (Sweden)

    Midyan D.I. Aldabash

    2016-03-01

    Full Text Available Sediment load materials is one of the key factors that determine the surface water quality, both of oceanic and river water, and it specifies water optical properties. Thus it provides a background for a plenty of applications and projects in the water and oceanography community. Landsat detects and classifies reflected solar energy from bodies on the earth's surface. Suspended sediments existing in water column have an optical influences. So that, Landsat images could detect suspended sediments concentration in such a water surface. In this study we have three main objectives to be achieved as; TSS Concentration maps generation in the Gaza Strip coastal zone, achieving analysis processes on TSS trend itself and TSS related coastal phenomenon, and investigation of the ability of Landsat images to detect TSS comprehensively in a wavy coastal zone. For this purpose two landsat TM5 images acquired in 1999 and 2010, one Landsat TM7 images acquired in 2003, and 2 Landsat Oli 8 images acquired in 2014 and 2015 were used for TSS mapping. In addition, 64 TSS in-situ tested samples were also to calculate a correlation equation between Digital Numbers - DN in each image pixels and TSS values in the ground data. All image analysis and remote sensing steps have been done in this study using Integrated Land and Water Information System - ILWIS software version ILWIS academic 3.3. Green and Red bands in all used Landsat images contained the highest linear correlation factors -R- for the images acquired in 1999, 2003, 2010, 2014, and 2015. Resulted correlation factors were higher by reducing time difference between acquisition time and sampling time. Generated maps showed that circulation in Gaza coastal area are counterclockwise, and it brings the sediments from Nile River Delta toward Gaza Strip.

  13. Metal Accumulation in Surface Sediment of the Urban and Industrial Coastal Area of the Municipality of Moa (Cuba: Distribution and Pollution Assessment

    Directory of Open Access Journals (Sweden)

    Yosbanis Cervantes-Guerra

    2017-04-01

    Full Text Available The investigation is to evaluate the accumulation of ten elements (Al, Cr, Fe, Mn, Ni, Co, As, Cu, Pb and Zn in surface sediments from the urban and industrial coastal area of Moa. Human activity has influenced the region, which has been developing in one of the most important mining regions of Cuba since the middle of the past century. Two methods were used to assess the contamination of the sediments: the estimation of metal enrichment by calculating the index of geo-accumulation (Igeo and the interpretation of the data obtained based on quality criteria. The overall range of concentrations is 15.7 - 83.5 mg g-1 for aluminum, 1.4 – 17.9 mg g-1 for chromium, 22.8 - 379.5 mg g-1 for iron, 1.5 - 56.2 mg g-1 for manganese, 0.9 – 6.2 mg g-1 for nickel, 56 - 1094 µg g-1 for cobalt, 6 - 126 µg g-1 for arsenic, 17 to 146 µg g-1 for copper, 6 - 66 µg g-1 for lead, and 64 - 576 µg g-1 for zinc. The results obtained from the studied coastal zone show a high level of pollution in surface sediments. The spatial distribution of the elements varied according to the analyzed elements: Al, Cr, Fe and Ni showed high levels of concentration throughout the studied zone; Mn, Co, Cu, As and Zn are in a higher proportion in Moa Bay Cay. In the case of As and Pb, higher concentrations were located at the deltas of Moa and Cayo Guam rivers and also in some areas in the west of the bay.

  14. Speciation and Mobility of Some Heavy Metals in the Coastal Sediments of Jeddah, Eastern Red Sea

    International Nuclear Information System (INIS)

    El-Sayed, Mohamed A.; Basaham, Ali S.

    2004-01-01

    Total and potentially mobile fractions of Fe, Mn, Cu, Zn and Pb were analyzed in 28 sediment samples collected from the coastal area of Jeddah. Sampling sites were selected from the coastal area of Jeddah. Sampling sites were selected to represent heavily sewage polluted areas and areas far from the effect of direct sewage dumping. Total concentrations reflected the degree of contamination and were particularly high in the confined environments. Concentrations in the mud fraction (<63um) were 3 to 6 times higher than that in the sand fraction. The repartition of elements between the exchangeable, reducible, oxidizable and residual fraction either as a constituent of the detrital material and/or trapped in the form of insoluble sulphides. Dominance of the exchangeable fraction characterized the speciation of Mn. Mobilization of Mn under reducing conditions and its readsorption on the particle surface is a probable explanation. Cu and Zn appear to have comparable distribution between the different fractions, however, Cu seems preferntially associated with the oxidizable fractions while reducing Zn was slightly more important than the other forms. Pb was particularly distributed between the oxidizable and the exchangeable fraction. Residual Pb participation was very low and sometimes totally absent. The interest behind the use of speciation schemes is that it permits the distinction between the fraction of the element that could be released into the water when the physico-chemical conditions are modified and the part that is permanently or quasi permanently fixed in the sediments. Most of the Fe was found held in the residual unavailable form while most of Mn, Cu, Zn and Pb were distributed between the environmentally unstable, exchangeable, oxidizable and reducible fractions. Therefore, these elements are supposed to have greater mobility and may, under particular conditions, greatly influence the environmental characteristics. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    JE Szecsody; JS Fruchter; DS Sklarew; JC Evans

    2000-03-21

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

  16. Surface Sediment Analysis on Petroleum Hydrocarbon and Total Organic Carbon from Coastal Area of Papar to Tuaran, Sabah

    International Nuclear Information System (INIS)

    Siti Aishah Mohd Ali; Payus, C.; Masni Mohd Ali

    2015-01-01

    Total petroleum hydrocarbons (TPH) and total organic carbon (TOC) were investigated in surface sediments along coastal area of Papar to Tuaran, Sabah. Surface sediment samples were collected in 24 different stations in each area by using Ponar grab sampler. Samples were extracted for TPH using standard method sediment/ sludge APHA 5520E and analyzed using UV/VIS spectrophotometer while for TOC method analysis using United Nations Environment Programme (UNEP)/ MAP Athens (2006). The range of TPH concentrations in surface sediments were recorded at 0.24 - 20.65 mg/ kg dw Miri crude oil equivalents, meanwhile the TOC percentage ranged from 0.03 - 4.02 %. In the mean time, the statistical analysis by Pearson correlation showed a positive correlation with coefficient, r = 0.790 which showing the TPH concentrations significantly have influence on the TOC accumulations in the surface sediment. (author)

  17. Formation of ferric iron crusts in Quaternary sediments of Lake Baikal, Russia, and implications for paleoclimate

    Science.gov (United States)

    Deike, R.G.; Granina, L.; Callender, E.; McGee, J.J.

    1997-01-01

    Phosphate-bearing, ferric iron and siliceous crusts ranging in age from Recent to approximately 65,000 yr B.P. are observed in sediments of Lake Baikal. In younger sediments the crusts are at the base of a spectrum of secondary iron and manganese oxides that accumulate near the sediment/water interface in the zone of positive oxidation potential beneath an oxygenated water column. In areas where the average Quaternary sedimentation rates have been slow (e.g. 0.026 mm/yr), the crusts are more common, and span a wider range of ages. No crusts have been found where the Quaternary sedimentation mode has been deltaic and rapid (0.15 mm/yr). Independent core correlation based on magnetic properties of the sediment suggests that crusts can be correlated over most of Academician Ridge, an area that is particularly sensitive to climatic events affecting the concentration of suspended sediment. These crusts may be indicative of periods of low suspended sediment concentration, which occur during sustained transitions from glacial periods of high detrital input, to interglacial periods of high diatom sedimentation. The crusts are dominated by iron-rich and siliceous amorphous mineral phases, with an FeO:SiO2 by weight of 3:1. Regardless of age or location in the lake the Fe phase always includes Ca, P and Mn. Extensive microprobe data for these four elements recast as normalized elemental weight percent reveal linear trends of Ca:P and Fe:P. With increasing P, Ca also increases such that the two elements maintain a linear relationship passing very close to the origin and with a mean molar Ca:P=0.3 (too low for well-characterized apatite). Conversely, with increasing P, Fe decreases (mean molar Fe:P=3.4). There is no correlation between Mn and P. Molar Fe:P ratios for vivianite (an Fe(II) phosphate mineral observed in sediments closely below some crusts) are clustered around a stoichiometric composition. The covariant increase in Ca:P and the corresponding decrease in Fe:P may

  18. Assessment of arsenic in coastal sediments, seawaters and molluscs in the Tarut Island, Arabian Gulf, Saudi Arabia

    Science.gov (United States)

    El-Sorogy, Abdelbaset S.; Youssef, Mohamed; Al-Kahtany, Khaled; Al-Otaiby, Naif

    2016-01-01

    In order to assess arsenic on the Tarut coast, Saudi Arabian Gulf, 38 sediment samples, 26 seawater samples and 40 gastropod and bivalve specimens were collected for analyses by Inductively Coupled Plasma-Mass Spectrometer. The Enrichment Factor (EF), the Geoaccumulation Index (Igeo) and the Contamination Factor (CF) indicated that coastal sediments of Tarut Island are severely enriched, strongly polluted and very highly contaminated with arsenic as a result of anthropogenic inputs. Comparison with arsenic in coastal sediments, seawaters and molluscs in the Red Sea, the Arabian Gulf and abroad coasts suggested that the studied samples have higher concentrations of As. The suggested natural sources of arsenic in the study area are the weathering and decomposition of neighboring deserts. The anthropogenic sources include the land reclamation, petrochemical industries, boat exhaust emissions, oil leakage, desalination plants and sewage effluents. These anthropogenic sources are the dominant sources of As in the study area and mostly came from Al Jubail industrial city to the north.

  19. Inorganic arsenic and iron(II) distributions in sediment porewaters investigated by a combined DGTcolourimetric DET technique

    DEFF Research Database (Denmark)

    Bennett, William W.; Teasdale, Peter R.; Welsh, David T.

    2012-01-01

    A new approach for investigating the biogeochemistry of inorganic arsenic and iron(II) in freshwater, estuarine and marine sediments is reported. The recently developed Metsorb diffusive gradients in thin films (DGT) technique for the measurement of total inorganic arsenic and the colourimetric d...... highly representative assessment of the biogeochemical status of arsenic and iron in a variety of natural sediments, including groundwater sediments where mobilised arsenic is responsible for significant human health risks.......A new approach for investigating the biogeochemistry of inorganic arsenic and iron(II) in freshwater, estuarine and marine sediments is reported. The recently developed Metsorb diffusive gradients in thin films (DGT) technique for the measurement of total inorganic arsenic and the colourimetric...... diffusive equilibration in thin films (DET) technique for the measurement of iron(II), were utilised in combination to determine co-located depth profiles of both solutes in sediment porewaters. DGT-measured porewater arsenic concentrations were typically less than 40nM, whereas iron(II) concentrations...

  20. Combined influence of sedimentation and vegetation on the soil carbon stocks of a coastal wetland in the Changjiang estuary

    Science.gov (United States)

    Zhang, Tianyu; Chen, Huaipu; Cao, Haobing; Ge, Zhenming; Zhang, Liquan

    2017-07-01

    Coastal wetlands play an important role in the global carbon cycle. Large quantities of sediment deposited in the Changjiang (Yangtze) estuary by the Changjiang River promote the propagation of coastal wetlands, the expansion of saltmarsh vegetation, and carbon sequestration. In this study, using the Chongming Dongtan Wetland in the Changjiang estuary as the study area, the spatial and temporal distribution of soil organic carbon (SOC) stocks and the influences of sedimentation and vegetation on the SOC stocks of the coastal wetland were examined in 2013. There was sediment accretion in the northern and middle areas of the wetland and in the Phragmites australis marsh in the southern area, and sediment erosion in the Scirpus mariqueter marsh and the bare mudflat in the southern area. More SOC accumulated in sediments of the vegetated marsh than in the bare mudflat. The total organic carbon (TOC) stocks increased in the above-ground biomass from spring to autumn and decreased in winter; in the below-ground biomass, they gradually increased from spring to winter. The TOC stocks were higher in the below-ground biomass than in the above-ground biomass in the P. australis and Spartina alterniflora marshes, but were lower in the below-ground biomass in S. mariqueter marsh. Stocks of SOC showed temporal variation and increased gradually in all transects from spring to winter. The SOC stocks tended to decrease from the high marsh down to the bare mudflat along the three transects in the order: P. australis marsh > S. alterniflora marsh > S. mariqueter marsh > bare mudflat. The SOC stocks of the same vegetation type were higher in the northern and middle transects than in the southern transect. These results suggest that interactions between sedimentation and vegetation regulate the SOC stocks in the coastal wetland in the Changjiang estuary.

  1. Benthic fluxes of mercury during redox changes in pristine coastal marine sediments from the Gulf of Trieste (northern Adriatic Sea)

    Energy Technology Data Exchange (ETDEWEB)

    Koron, Neza [National Institute of Biology, Piran (Slovenia). Marine Biological Section; Faganeli, Jadran [National Institute of Biology, Piran (Slovenia). Marine Biological Section; Jozef Stefan Institute, Ljubljana (Slovenia). Dept. of Environmental Sciences

    2012-12-15

    Purpose: The Gulf of Trieste (northern Adriatic Sea) is an example of a coastal environment contaminated with mercury (Hg). Contamination is a consequence of nearly 500 years of activity at the Idrija Mine (western Slovenia), which is the second largest Hg mine in the world. Oxygen depletion can be common in the Gulf of Trieste due to late summer stratification of the water column and accumulation of labile organic matter. Since changing redox conditions can have an impact on Hg transformations, we studied the effect of oxygen depletion, in parallel with sulphide, iron (Fe), manganese (Mn), fluorescent dissolved organic matter (FDOM) and nitrogen (N) and phosphorus (P) availability, on total Hg and methylmercury (MeHg) fluxes from sediments. Materials and methods: Pore water concentrations and benthic fluxes of total dissolved Hg and MeHg were studied in situ and in microcosm laboratory experiments using flux chambers encompassing three different stages: oxic, anoxic and reoxidation. Results and discussion: Our experiments showed that in the oxic stage there were small effluxes of MeHg to the water column, which increased in the anoxic stage and dropped rapidly in a subsequent reoxic stage, showing influx. Our results support the hypothesis that MeHg desorption from reduced metal hydroxides under anoxic conditions, and co-precipitation with Fe-oxides and MeHg demethylation in the reoxidation stage, may play a major role in determining MeHg benthic fluxes. For Hg and MeHg, it appears that there is little relationship between their pore water distribution and flux and that of FDOM, i.e. humics. Conclusions: The results indicate that there was no significant difference in Hg and MeHg pore water levels and their benthic fluxes between the contaminated northern and central parts of the Gulf of Trieste and the pristine southern part. This suggests that shallow and stratified coastal marine environments, in general, represent areas with a risk of high benthic release of

  2. Determination of sedimentation, diffusion, and mixing rates in coastal sediments of the eastern Red Sea via natural and anthropogenic fallout radionuclides.

    Science.gov (United States)

    Al-Mur, Bandar A; Quicksall, Andrew N; Kaste, James M

    2017-09-15

    The Red Sea is a unique ecosystem with high biodiversity in one of the warmest regions of the world. In the last five decades, Red Sea coastal development has rapidly increased. Sediments from continental margins are delivered to depths by advection and diffusion-like processes which are difficult to quantify yet provide invaluable data to researchers. Beryllium-7, lead-210 and ceseium-137 were analyzed from sediment cores from the near-coast Red Sea near Jeddah, Saudi Arabia. The results of this work are the first estimates of diffusion, mixing, and sedimentation rates of the Red Sea coastal sediments. Maximum chemical diffusion and particle mixing rates range from 69.1 to 380cm -2 y -1 and 2.54 to 6.80cm -2 y -1 , respectively. Sedimentation rate is constrained to approximately 0.6cm/yr via multiple methods. These data provide baselines for tracking changes in various environmental problems including erosion, marine benthic ecosystem silting, and particle-bound contaminant delivery to the seafloor. Copyright © 2017. Published by Elsevier Ltd.

  3. Metagenomics unveils the attributes of the alginolytic guilds of sediments from four distant cold coastal environments: Alginolytic guilds from cold sediments

    Energy Technology Data Exchange (ETDEWEB)

    Matos, Marina N. [Laboratorio de Microbiología Ambiental, Centro para el Estudio de Sistemas Marinos (CESIMAR, CONICET), Puerto Madryn U9120ACD Argentina; Lozada, Mariana [Laboratorio de Microbiología Ambiental, Centro para el Estudio de Sistemas Marinos (CESIMAR, CONICET), Puerto Madryn U9120ACD Argentina; Anselmino, Luciano E. [Laboratorio de Microbiología Ambiental, Centro para el Estudio de Sistemas Marinos (CESIMAR, CONICET), Puerto Madryn U9120ACD Argentina; Musumeci, Matías A. [Laboratorio de Microbiología Ambiental, Centro para el Estudio de Sistemas Marinos (CESIMAR, CONICET), Puerto Madryn U9120ACD Argentina; Henrissat, Bernard [Architecture et Fonction des Macromolécules Biologiques, CNRS, Aix-Marseille Université, Marseille 13288 France; INRA, USC 1408 AFMB, Marseille F-13288 France; Department of Biological Sciences, King Abdulaziz University, Jeddah 21589 Saudi Arabia; Jansson, Janet K. [Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Mac Cormack, Walter P. [Instituto Antártico Argentino, Ciudad Autónoma de Buenos Aires, C1064ABR, Argentina; Instituto Nanobiotec, CONICET - Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, C1113AAC, Argentina; Carroll, JoLynn [Akvaplan-niva, Fram - High North Research Centre for Climate and the Environment, Tromsø NO-9296 Norway; CAGE - Centre for Arctic Gas Hydrate, Environment and Climate, UiT The Arctic University of Norway, Tromsø N-9037 Norway; Sjöling, Sara [School of Natural Sciences and Environmental Studies, Södertörn University, Huddinge 141 89 Sweden; Lundgren, Leif [Stockholm University, Stockholm SE-106 91 Sweden; Dionisi, Hebe M. [Laboratorio de Microbiología Ambiental, Centro para el Estudio de Sistemas Marinos (CESIMAR, CONICET), Puerto Madryn U9120ACD Argentina

    2016-07-18

    Alginates are abundant polysaccharides in brown algae that constitute an important energy source for marine heterotrophic bacteria. Despite the key role of alginate assimilation processes in the marine carbon cycle, little information is available on the bacterial populations involved in these processes. The goal of this work was to gain insight into the structure and functional traits of the alginolytic communities from sediments of cold coastal environments. Sediment metagenomes from high-latitude regions of both Hemispheres were interrogated for alginate lyase gene homolog sequences and their genomic context. Sediments contained highly abundant and diverse bacterial assemblages with alginolytic potential, including members of Bacteroidetes and Proteobacteria, as well as several poorly characterized taxa. Temperature and salinity were correlated to the variation in community structure. The microbial communities in Arctic and Antarctic sediments exhibited the most similar alginolytic profiles, whereas brackish sediments had a higher proportion of novel members. Examination of the gene context of the alginate lyase homologs revealed distinct patterns according to the phylogenetic origin of the scaffolds, with evidence of evolutionary relationships among lineages. This information is relevant for understanding carbon fluxes in cold coastal environments and provides valuable information for the development of biotechnological applications from brown algae biomass.

  4. Hydrogeochemical assessment of mine-impacted water and sediment of iron ore mining

    Science.gov (United States)

    Nur Atirah Affandi, Fatin; Kusin, Faradiella Mohd; Aqilah Sulong, Nur; Madzin, Zafira

    2018-04-01

    This study was carried out to evaluate the hydrogeochemical behaviour of mine-impacted water and sediment of a former iron ore mining area. Sampling of mine water and sediment were carried out at selected locations within the mine including the former mining ponds, mine tailings and the nearby stream. The water samples were analysed for their hydrochemical facies, major and trace elements including heavy metals. The water in the mining ponds and the mine tailings was characterised as highly acidic (pH 2.54-3.07), but has near-neutral pH in the nearby stream. Results indicated that Fe and Mn in water have exceeded the recommended guidelines values and was also supported by the results of geochemical modelling. The results also indicated that sediments in the mining area were contaminated with Cd and As as shown by the potential ecological risk index values. The total risk index of heavy metals in the sediment were ranked in the order of Cd>As>Pb>Cu>Zn>Cr. Overall, the extent of potential ecological risks of the mining area were categorised as having low to moderate ecological risk.

  5. Application of radiometric analysis in the study of provenance and transport processes of Brazilian coastal sediments

    International Nuclear Information System (INIS)

    Carvalho, C.; Anjos, R.M.; Veiga, R.; Macario, K.

    2011-01-01

    Natural gamma radiation of beach sand deposits was measured along the south coast of Rio de Janeiro State, Brazil, with the aim of studying the provenance and transport processes of sediments in this area. Concentrations of thorium, uranium and potassium were evaluated using γ-ray spectrometry and a behavioral study of eTh/eU and eTh/K cross plots was performed, reflecting the mineralogical properties of beach sands, as well as their history of transport and sorting processes. The results show that such technique can be efficiently used to map heavy mineral distributions and to distinguish the different origins of coastal sediments disclosing the influence of nearby rivers. - Research highlights: → Based on the natural γ-ray analyses of beach sand, high concentrations of heavy minerals have been found around the Mambucaba River deltaic complex, located in the South of Rio de Janeiro State, Brazil. → Concentrations of thorium, uranium and potassium concentration can give information on the mineral composition and provenance of beach sands and consequently investigate heavy mineral deposits.

  6. Application of radiometric analysis in the study of provenance and transport processes of Brazilian coastal sediments

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, C. [Laboratorio de Radioecologia (LARA), Instituto de Fisica, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/no, Gragoata, 24210-346 Niteroi, RJ (Brazil); Anjos, R.M., E-mail: meigikos@if.uff.b [Laboratorio de Radioecologia (LARA), Instituto de Fisica, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/no, Gragoata, 24210-346 Niteroi, RJ (Brazil); Veiga, R.; Macario, K. [Laboratorio de Radioecologia (LARA), Instituto de Fisica, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/no, Gragoata, 24210-346 Niteroi, RJ (Brazil)

    2011-02-15

    Natural gamma radiation of beach sand deposits was measured along the south coast of Rio de Janeiro State, Brazil, with the aim of studying the provenance and transport processes of sediments in this area. Concentrations of thorium, uranium and potassium were evaluated using {gamma}-ray spectrometry and a behavioral study of eTh/eU and eTh/K cross plots was performed, reflecting the mineralogical properties of beach sands, as well as their history of transport and sorting processes. The results show that such technique can be efficiently used to map heavy mineral distributions and to distinguish the different origins of coastal sediments disclosing the influence of nearby rivers. - Research highlights: {yields} Based on the natural {gamma}-ray analyses of beach sand, high concentrations of heavy minerals have been found around the Mambucaba River deltaic complex, located in the South of Rio de Janeiro State, Brazil. {yields} Concentrations of thorium, uranium and potassium concentration can give information on the mineral composition and provenance of beach sands and consequently investigate heavy mineral deposits.

  7. Hydrodynamic and Sediment Transport Modelling of Suralaya Coastal Area, Cilegon, Indonesia

    Science.gov (United States)

    Fattah, A. H.; Suntoyo; Damerianne, H. A.; Wahyudi

    2018-03-01

    The coastal zone of Suralaya is located in the district Pulomerak, Cilegon City, Province Banten. This region is a part of the Sunda Strait region that is very important area to support the ongoing activities such as, industries, power plant, ports, and tourism. However, those various activities will certainly give effect to the surrounding environment. To determine the environmental conditions of Suralaya Coast, it is necessary to study the hydrodynamics analysis and sediment transport modelling including the analysis of currents patterns. Tidal elevation observation was conducted for 15 days used to validate the water elevation simulation results, in which a good agreement between the observed data and the model result was obtained with the error value of 1.6%. The dominant current direction is from northeast in west season, while in the east season predominant current direction is from northwest with a speed average current 12,44 cm/s. The dominant wave direction is from the west. The average temperature is at 27°C and the bottom sediment dominant form is fine sand.

  8. Seagrasses and sediment response to changing physical forcing in a coastal lagoon

    Directory of Open Access Journals (Sweden)

    J. Figueiredo da Silva

    2004-01-01

    Full Text Available The Ria de Aveiro is an estuary–coastal lagoon system connected to the Atlantic Ocean by a channel with a cross-sectional area that, for more than a century, has increased steadily, partly because of dredging over the last 50 years. Local ocean tides, with amplitudes of up to 3 m, are today transmitted to the lagoon by the single, engineered inlet channel and propagate to the end of the lagoon channels as a damped progressive wave. The increase in tidal amplitude with time has affected the lagoon ecosystem and the water has become more saline. Seagrass beds are important indicators of ecosystem change; until 1980, much of the lagoon bed was covered by seagrasses (Zostera, Ruppia, Potamogeton, which were collected in large quantities for use in agriculture. After 1960, the harvesting declined and the seagrass beds became covered in sediment, so that the area of seagrasses decreased substantially despite the decline in the quantity collected. The change in the pattern of seagrass populations can be related to changes in the physical forcing associated with increased tidal wave penetration. This has, in turn, induced transport and redistribution of coarser, sandy sediment and increased re-suspension and turbidity in the water column. However, the initiating cause for this ecosystem change was dredging, which, since the 1950s, has been used increasingly to widen and deepen the channels of the system.

  9. Coastal marsh degradation: modeling the influence of vegetation die-off patterns on flow and sedimentation

    Science.gov (United States)

    Schepers, Lennert; Wang, Chen; Kirwan, Matthew; Belluco, Enrica; D'Alpaos, Andrea; Temmerman, Stijn

    2014-05-01

    Coastal marshes are vulnerable ecosystems that provide ecosystem functions such as storm protection and carbon sequestration. However, degradation of vegetated marshes into bare tidal flats or open water has been reported as a worldwide phenomenon, threatening their valuable wetland functions. Moreover, tidal marshes and bare flats are considered as alternative stable ecosystem states, which implies that, once vegetated marshes have degraded to bare flats, the (re)conversion from bare flats to marsh vegetation may be very difficult. Recent aerial photo analysis has demonstrated that the degradation or die-off of a marsh area is a spatial process, whereby vegetation is typically replaced by non-vegetated areas in the form of interior marsh pools, also known as ponds or marsh basins. On a small scale, these pools have similar characteristics among different marshes worldwide: pools that are located further away from tidal channels and with broad channel connections to the tidal channel system appear to have low surface elevations and a low probability for marsh recovery (this is re-establishment of vegetation on the surface). Interior pools located closer to, but that are not connected to channels on the other hand, are positioned on higher elevations and are more likely to recover. These findings may have important implications for the restoration potential of degraded marshes and their functions. We hypothesize that bio-geomorphologic interactions are the main mechanisms causing these differences in elevation and recovery potential of interior marsh pools: pools that are not connected to the channel system, are separated from the channel by vegetation, which reduces the flow velocity, increases sedimentation and may explain our observation of higher surface elevation of this type of pools. In contrast, pools that are connected with the channel system are not protected by vegetation and will experience higher flow velocities and lower sedimentation rates or even

  10. Descriptions and preliminary report on sediment cores from the southwest coastal area, Everglades National Park, Florida

    Science.gov (United States)

    Wingard, G. Lynn; Cronin, Thomas M.; Holmes, Charles W.; Willard, Debra A.; Budet, Carlos A.; Ortiz, Ruth E.

    2005-01-01

    Sediment cores were collected from five locations in the southwest coastal area of Everglades National Park, Florida, in May 2004 for the purpose of determining the ecosystem history of the area and the impacts of changes in flow through the Shark River Slough. An understanding of natural cycles of change prior to significant human disturbance allows land managers to set realistic performance measures and targets for salinity and other water quality and quantity quality measures. Preliminary examination of the cores indicates significant changes have taken place over the last 1000-2000 years. The cores collected from the inner bays - the most landward bays - are distinctly different from other estuarine sediment cores examined in Florida Bay and Biscayne Bay. Peats in the inner-bay cores from Big Lostmans Bay, Broad River Bay, and Tarpon Bay were deposited at least 1000 years before present (BP) based on radiocarbon analyses. The peats are overlain by poorly sorted organic muds and sands containing species indicative of deposition in a freshwater to very low salinity environment. The Alligator Bay core, the most northern inner-bay core, is almost entirely sand; no detailed faunal analyses or radiometric dating has been completed on this core. The Roberts River core, taken from the mouth of the River where it empties into Whitewater Bay, is lithologically and faunally similar to previously examined cores from Biscayne and Florida Bays; however, the basal unit was deposited ~2000 years before the present based on radiocarbon analyses. A definite trend of increasing salinity over time is seen in the Roberts River core, from sediments representing a terrestrially dominated freshwater environment at the bottom of the core to those representing an estuarine environment with a strong freshwater influence at the top. The changes seen at Roberts River could represent a combination of factors including rising sea-level and changes in freshwater supply, but the timing and

  11. Variation of 210Po and 210Pb Profile in the Sediment Core of Sarawak Coastal Waters

    International Nuclear Information System (INIS)

    Zal U'yun Wan Mahmood; Che Abd Rahim Mohamed; Zaharudin Ahmad; Abdul Kadir Ishak

    2008-01-01

    This study was performed to observe the variation in the distribution of 210 Po and 210 Pb through their activity vertical profile and 210 Po/ 210 Pb activity ratio in the sediment cores that were taken at some sampling stations in the Sarawak coastal waters. It was found that the distribution profile of those radionuclide in the sediment cores varied depending on the sampling location and ANOVA analysis shows significant difference at 95% confidence level for activities of 210 Po (p = 0.000), 210 Pb (p = 0.035) and 210 Po/ 210 Pb (p = 0.000) at all study locations. Generally, the measured activity of 210 Po and 210 Pb ranged from 337 to 2460 Bq/ kg, 11 to 84 Bq/ kg at SR 01; 224 to 2008 Bq/ kg, 6 to 80 Bq/ kg at SR 02; 119 to 1595 Bq/ kg, 6 to 84 Bq/ kg at SR 03; 241 to 2294 Bq/ kg, 5 to 82 Bq/ kg at SR 04 and 175 to 1340 Bq/ kg, 4 to 44 Bq/ kg at SR 05, respectively. In those range it was found that 210 Po activities were higher than 210 Pb with average of 210 Po/ 210 Pb ratios at all stations were from 20 to 35. The variation in the distribution profile for the radionuclides are believed to be influenced by some environmental factors and have strong correlation between the radionuclide distribution and the sediment composition of silt ( 210 Po: r = 0.701 and 210 Pb: r = 0.648), water depth ( 210 Po: r = -0.647) and the distance from the sampling station to the main land ( 210 Po: r = 0.746 and 210 Pb: r = 0.975). Those factors are a major contributions on the variation of 210 Po and 210 Pb in the samples. (author)

  12. Metal concentrations and mobility in marine sediment and groundwater in coastal reclamation areas: A case study in Shenzhen, China

    International Nuclear Information System (INIS)

    Chen Kouping; Jiao, Jiu J.

    2008-01-01

    The concentrations of metals in the buried marine sediment and groundwater were differently affected by land reclamation. Nine metals (V, Cr, Mn, Co, Ni, Cu, Zn, Cd and Pb) in sediment and coastal groundwater from reclamation areas in Shenzhen were examined. The gradually decreased concentrations (V, Cr, Mn, Ni, Cu, Zn) in sediment and relatively higher concentrations (V, Cr, Mn, Co, Ni, Cu and Cd) in groundwater within reclamation areas were observed. The increase of V, Cr, Mn, Ni, Cu and Cd concentrations in groundwater within reclamation areas subsequently after land reclamation should be resulted from the mobilization of these metals accumulated in the sediment. These metals appear to be easily mobilized from solid phase to solution phase after reclamation. The physico-chemical changes such as reduction in pH and salinity in water environment induced by land reclamation appear to be responsible for metal mobility in the sediment-groundwater system. - Metals in coastal groundwater and marine sediment are affected by land reclamation

  13. Metal release from contaminated coastal sediments under changing pH conditions: Implications for metal mobilization in acidified oceans.

    Science.gov (United States)

    Wang, Zaosheng; Wang, Yushao; Zhao, Peihong; Chen, Liuqin; Yan, Changzhou; Yan, Yijun; Chi, Qiaoqiao

    2015-12-30

    To investigate the impacts and processes of CO2-induced acidification on metal mobilization, laboratory-scale experiments were performed, simulating the scenarios where carbon dioxide was injected into sediment-seawater layers inside non-pressurized chambers. Coastal sediments were sampled from two sites with different contamination levels and subjected to pre-determined pH conditions. Sediment samples and overlying water were collected for metal analysis after 10-days. The results indicated that CO2-induced ocean acidification would provoke increased metal mobilization causing adverse side-effects on water quality. The mobility of metals from sediment to the overlying seawater was correlated with the reduction in pH. Results of sequential extractions of sediments illustrated that exchangeable metal forms were the dominant source of mobile metals. Collectively, our data revealed that high metal concentrations in overlying seawater released from contaminated sediments under acidic conditions may strengthen the existing contamination gradients in Maluan Bay and represent a potential risk to ecosystem health in coastal environments. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Polycyclic aromatic hydrocarbons and black carbon in intertidal sediments of China coastal zones: Concentration, ecological risk, source and their relationship

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiaofei [School of Geographical Sciences, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062 (China); Hou, Lijun [State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062 (China); Li, Ye [School of Geographical Sciences, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062 (China); Liu, Min, E-mail: mliu@geo.ecnu.edu.cn [School of Geographical Sciences, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062 (China); Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062 (China); Lin, Xianbiao; Cheng, Lv [School of Geographical Sciences, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062 (China)

    2016-10-01

    Polycyclic aromatic hydrocarbons (PAHs) and black carbon (BC) have attracted many attentions, especially in the coastal environments. In this study, spatiotemporal distributions of PAHs and BC, and the correlations between BC and PAHs were investigated in the intertidal sediments of China coastal zones. BC in sediments was measured through dichromate oxidation (BC{sub Cr}) and thermal oxidation (BC{sub CTO}). The concentrations of BC{sub Cr} in the intertidal sediments ranged between 0.61 and 6.32 mg g{sup −1}, while BC{sub CTO} ranged between 0.57 and 4.76 mg g{sup −1}. Spatial variations of δ{sup 13}C signatures in TOC and BC were observed, varying from − 21.13‰ to − 24.87‰ and from − 23.53‰ to − 16.78‰, respectively. PAH contents of sediments ranged from 195.9 to 4610.2 ng g{sup −1} in winter and 98.2 to 2796.5 ng g{sup −1} in summer, and significantly seasonal variations were observed at most sampling sites. However, the results of potential toxicity assessment indicated low ecological risk in the intertidal sediments of China coastal zones. Greater concentrations of PAHs measured in the sediments of estuarine environments indicated that rivers runoff may have been responsible for the higher PAH pollution levels in the intertidal sediments of China coastal zones. Pearson's correlation analysis suggested that pyrogenic compounds of PAH were significantly related to BC, due to that both BC and these compounds derived mainly from the combustion process of fossil fuels and biomass. Overall, increasing energy consumptions caused by anthropogenic activities can contribute more emissions of BC as well as PAHs and thus improve the importance of BC in indicating pyrogenic compounds of PAHs in the intertidal sediments of China coastal zones. - Highlights: • River runoffs were responsible for the high PAH pollution levels in the study area. • BC and PAHs derived mainly from the combustion process of fossil fuels. • BC was associated

  15. 2,4,6-Trinitrotoluene mineralization and bacterial production rates of natural microbial assemblages from coastal sediments

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, Michael T., E-mail: michael.montgomery@nrl.navy.mil [Naval Research Laboratory, Marine Biogeochemistry Section, Code 6114, 4555 Overlook Avenue, Washington, DC 20375 (United States); Coffin, Richard B., E-mail: richard.coffin@nrl.navy.mil [Naval Research Laboratory, Marine Biogeochemistry Section, Code 6114, 4555 Overlook Avenue, Washington, DC 20375 (United States); Boyd, Thomas J., E-mail: thomas.boyd@nrl.navy.mil [Naval Research Laboratory, Marine Biogeochemistry Section, Code 6114, 4555 Overlook Avenue, Washington, DC 20375 (United States); Smith, Joseph P., E-mail: joseph.smith@nrl.navy.mil [Naval Research Laboratory, Marine Biogeochemistry Section, Code 6114, 4555 Overlook Avenue, Washington, DC 20375 (United States); Walker, Shelby E., E-mail: Shelby.Walker@noaa.gov [Naval Research Laboratory, Marine Biogeochemistry Section, Code 6114, 4555 Overlook Avenue, Washington, DC 20375 (United States); Osburn, Christopher L., E-mail: chris_osburn@ncsu.edu [Marine, Earth and Atmospheric Sciences, North Carolina State University, Raleigh, NC 27695 (United States)

    2011-12-15

    The nitrogenous energetic constituent, 2,4,6-Trinitrotoluene (TNT), is widely reported to be resistant to bacterial mineralization (conversion to CO{sub 2}); however, these studies primarily involve bacterial isolates from freshwater where bacterial production is typically limited by phosphorus. This study involved six surveys of coastal waters adjacent to three biome types: temperate broadleaf, northern coniferous, and tropical. Capacity to catabolize and mineralize TNT ring carbon to CO{sub 2} was a common feature of natural sediment assemblages from these coastal environments (ranging to 270+/-38 {mu}g C kg{sup -1} d{sup -1}). More importantly, these mineralization rates comprised a significant proportion of total heterotrophic production. The finding that most natural assemblages surveyed from these ecosystems can mineralize TNT ring carbon to CO{sub 2} is consistent with recent reports that assemblage components can incorporate TNT ring carbon into bacterial biomass. These data counter the widely held contention that TNT is recalcitrant to bacterial catabolism of the ring carbon in natural environments. - Highlights: > TNT mineralization is a common feature of natural bacterial assemblages in coastal sediments. > TNT mineralization rates comprised a significant proportion of total heterotrophic production. > These data counter the widely held contention that TNT is recalcitrant to bacterial catabolism of the ring carbon in natural environments. - The capacity to mineralize TNT ring carbon to CO{sub 2} is a common feature of natural bacterial assemblages in coastal sediment.

  16. Chronic polyaromatic hydrocarbon (PAH contamination is a marginal driver for community diversity and prokaryotic predicted functioning in coastal sediments

    Directory of Open Access Journals (Sweden)

    Mathilde Jeanbille

    2016-08-01

    Full Text Available Benthic microorganisms are key players in the recycling of organic matter and recalcitrant compounds such as polyaromatic hydrocarbons (PAHs in coastal sediments. Despite their ecological importance, the response of microbial communities to chronic PAH pollution, one of the major threats to coastal ecosystems, has received very little attention. In one of the largest surveys performed so far on coastal sediments, the diversity and composition of microbial communities inhabiting both chronically contaminated and non-contaminated coastal sediments were investigated using high-throughput sequencing on the 18S and 16S rRNA genes. Prokaryotic alpha-diversity showed significant association with salinity, temperature, and organic carbon content. The effect of particle size distribution was strong on eukaryotic diversity. Similarly to alpha-diversity, beta-diversity patterns were strongly influenced by the environmental filter, while PAHs had no influence on the prokaryotic community structure and a weak impact on the eukaryotic community structure at the continental scale. However, at the regional scale, PAHs became the main driver shaping the structure of bacterial and eukaryotic communities. These patterns were not found for PICRUSt predicted prokaryotic functions, thus indicating some degree of functional redundancy. Eukaryotes presented a greater potential for their use as PAH contamination biomarkers, owing to their stronger response at both regional and continental scales.

  17. 2,4,6-Trinitrotoluene mineralization and bacterial production rates of natural microbial assemblages from coastal sediments

    International Nuclear Information System (INIS)

    Montgomery, Michael T.; Coffin, Richard B.; Boyd, Thomas J.; Smith, Joseph P.; Walker, Shelby E.; Osburn, Christopher L.

    2011-01-01

    The nitrogenous energetic constituent, 2,4,6-Trinitrotoluene (TNT), is widely reported to be resistant to bacterial mineralization (conversion to CO 2 ); however, these studies primarily involve bacterial isolates from freshwater where bacterial production is typically limited by phosphorus. This study involved six surveys of coastal waters adjacent to three biome types: temperate broadleaf, northern coniferous, and tropical. Capacity to catabolize and mineralize TNT ring carbon to CO 2 was a common feature of natural sediment assemblages from these coastal environments (ranging to 270+/-38 μg C kg -1 d -1 ). More importantly, these mineralization rates comprised a significant proportion of total heterotrophic production. The finding that most natural assemblages surveyed from these ecosystems can mineralize TNT ring carbon to CO 2 is consistent with recent reports that assemblage components can incorporate TNT ring carbon into bacterial biomass. These data counter the widely held contention that TNT is recalcitrant to bacterial catabolism of the ring carbon in natural environments. - Highlights: → TNT mineralization is a common feature of natural bacterial assemblages in coastal sediments. → TNT mineralization rates comprised a significant proportion of total heterotrophic production. → These data counter the widely held contention that TNT is recalcitrant to bacterial catabolism of the ring carbon in natural environments. - The capacity to mineralize TNT ring carbon to CO 2 is a common feature of natural bacterial assemblages in coastal sediment.

  18. Toxicities of sediments below 10 effluent outfalls to near-coastal areas of the Gulf of Mexico

    International Nuclear Information System (INIS)

    Lewis, M.; Weber, D.; Stanley, R.

    1995-01-01

    The chemical quality and toxicities of sediments collected in the receiving waters below 10 wastewater outfalls to Northwest Florida coastal areas were evaluated at multiple stations during 1994--1996. Eight types of toxicity tests using 11 test species were used to assess acute and chronic toxicity of the sediments collected below industrial, municipal, power generation and pulp mill outfalls. The primary objectives of the study were to evaluate the relative ability of different assessment procedures to detect toxicity and to provide some much-needed perspective on the impact of major point sources on sediment quality in Gulf of Mexico estuaries. The major chemical contaminants were heavy metals and PAHs. Acute and chronic toxicities were noted. Results of tests with sediment collected at the same location but several months later often differed. The most sensitive species were mysids and an estuarine amphipod. The least sensitive species were fish and macrophyte seedlings. There was poor correlation of effluent toxicity to sediment toxicity in the receiving water. Toxicity of the effluents was greater than that of the sediments. Overall, the unavailability of relevant chronic toxicity methods, uncertain criteria for choice of control stations, lack of guidance on frequency of testing and the dynamic physical and chemical characteristics of sediments are factors that need consideration if sediment monitoring is to be part of the NPDES regulatory process

  19. Study of heavy metal pollution in mangrove sediments reference to marine environment along the coastal areas of Pakistan

    International Nuclear Information System (INIS)

    Khattak, M.I.; Khattak, M.I.

    2011-01-01

    The aim of this paper is to measure the concentration of heavy metals (Cd, Co, Pb, Cr, Zn, Cu and Fe) in Mangrove sediments. The concentrations of heavy metals (Cd, Co, Pb, Cr, Zn, Cu and Fe) were measured in different samples of in different Mangroves sediments along the coastal areas of Pakistan and was found that concentration of heavy metals in the Mangrove sediments near to Lyari and Malir river discharge points are at much higher level than the Mangrove sediments of Port Qasim area which are not according to WHO standard and are very are very serious health hazardous. In addition to point sources, possible reasons of non point sources were also discussed. (author)

  20. Simulation of the fate of faecal bacteria in estuarine and coastal waters based on a fractionated sediment transport model

    Science.gov (United States)

    Yang, Chen; Liu, Ying

    2017-08-01

    A two-dimensional depth-integrated numerical model is refined in this paper to simulate the hydrodynamics, graded sediment transport process and the fate of faecal bacteria in estuarine and coastal waters. The sediment mixture is divided into several fractions according to the grain size. A bed evolution model is adopted to simulate the processes of the bed elevation change and sediment grain size sorting. The faecal bacteria transport equation includes enhanced source and sink terms to represent bacterial kinetic transformation and disappearance or reappearance due to sediment deposition or re-suspension. A novel partition ratio and dynamic decay rates of faecal bacteria are adopted in the numerical model. The model has been applied to the turbid water environment in the Bristol Channel and Severn estuary, UK. The predictions by the present model are compared with field data and those by non-fractionated model.

  1. Distribution, enrichment and sources of thallium in the surface sediments of the southwestern coastal Laizhou Bay, Bohai Sea.

    Science.gov (United States)

    Zhuang, Wen; Gao, Xuelu

    2015-07-15

    The concentrations of thallium (Tl) in the surface sediments of the southwestern coastal Laizhou Bay and the rivers it connects were determined. In riverine sediments, the Tl concentrations ranged from 0.34 to 0.76 μg g(-1) in summer; in autumn, the corresponding data were 0.35-1.08 μg g(-1). In marine sediments, the Tl concentrations ranged from 0.36 to 0.58 μg g(-1) in summer; and from 0.30 to 0.56 μg g(-1) in autumn. The grain size, Al and Fe oxides were major factors affecting Tl distribution. Tl in the surface sediments of the studied area was mainly from the natural input with the non-natural input as a subsidiary source. The low concentrations of Tl made it hard to cause potential negative environmental effects in this area. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Distribution of Selected Heavy Metals in Sediment of the River Basin of Coastal Area of Chanthaburi Province, Gulf of Thailand

    Directory of Open Access Journals (Sweden)

    Jakkapan Potipat

    2015-01-01

    Full Text Available The sediment samples from 24 stations in coastal area of Chanthaburi Province were collected during March 2012 to March 2013 and analyzed for heavy metal contents (Pb, Cd, Cr, Fe, Cu and Zn, pH, organic matters and grain sizes. The correlation analyses showed that heavy metal concentrations were affected by the content of organic matter and the size of clay particles. The evaluation of the quality of sediment was carried out using the geoaccumulation index (Igeo and the enrichment factor (EF as well as the comparison with those in the Thailand's sediment quality guideline (SQG values. The results of the geoaccumulation index and the enrichment factor values of the heavy metals content in the sediments revealed that the study area was unpolluted and not enriched, respectively. The relationship between the heavy metals concentration and the organic matter, and the clay particle was proposed by using the multiple regression equations.

  3. Assessment of copper, cadmium and zinc remobilization in Mediterranean marine coastal sediments

    Science.gov (United States)

    Sakellari, Aikaterini; Plavšić, Marta; Karavoltsos, Sotiris; Dassenakis, Manos; Scoullos, Michael

    2011-01-01

    The remobilization of copper, cadmium and zinc in sediments of three selected coastal microenvironments of the Aegean Sea (Eastern Mediterranean) is assessed. Various analytical methods and techniques were employed providing concentrations, profiles and forms of metals and organic matter in sediments and pore waters. At Loutropyrgos, a non-industrial site located, however, within an intensively industrialized enclosed gulf, an intense resupply of zinc in pore water from sediment was recorded, correlating with the highest value of weakly bound fraction of zinc determined at this area. The comparatively high zinc concentrations measured in the pore waters (394 nM), exceed considerably those in the overlying seawater (12.5 nM determined by DGT; 13.5 nM total), resulting in the formation of a strong concentration gradient at the sediment-water interface. Potential zinc flux at the sediment-water interface at Loutropyrgos (based on 0.4 mm DGT profile) was calculated equal to 0.8 mmol.m -2.d -1. The half lives of trace metals at Loutropyrgos site, based on the aforementioned DGT profiles, amount to 0.1 y (Zn), 2.8 y (Cd), 4.5 y (Cu), 2.2 y (Mn) and 0.4 y (Fe) pointing out to the reactivity of these metals at the sediment-water interface. The concentration of dissolved organic carbon (DOC) in pore waters of the three selected sites (2.7-5.2 mg/L) was up to four times higher compared to that of the corresponding overlying seawater. Similarly, the concentrations of carbohydrates in pore waters (0.20-0.91 mg/L monosaccharides; 0.71-1.6 mg/L polysaccharides) are an order of magnitude higher than those of seawater, forming a concentration gradient at the sediment-water interface. Total carbohydrates contribute between 34 and 48% of the organic carbon of the pore waters, being significantly higher than those of seawater from the corresponding areas, which were in the range of 15-21%. The complexing capacity as for copper ions (CCu) determined in pore water ranges widely, from 0

  4. Estimation of settling velocity of sediment particles in estuarine and coastal waters

    Science.gov (United States)

    Nasiha, Hussain J.; Shanmugam, Palanisamy

    2018-04-01

    A model for estimating the settling velocity of sediment particles (spherical and non-spherical) in estuarine and coastal waters is developed and validated using experimental data. The model combines the physical, optical and hydrodynamic properties of the particles and medium to estimate the sediment settling velocity. The well-known Stokes law is broadened to account for the influencing factors of settling velocity such as particle size, shape and density. To derive the model parameters, laboratory experiments were conducted using natural flaky seashells, spherical beach sands and ball-milled seashell powders. Spectral light backscattering measurements of settling particles in a water tank were made showing a distinct optical feature with a peak shifting from 470-490 nm to 500-520 nm for particle populations from spherical to flaky grains. This significant optical feature was used as a proxy to make a shape determination in the present model. Other parameters experimentally determined included specific gravity (ΔSG) , Corey shape factor (CSF) , median grain diameter (D50) , drag coefficient (Cd) and Reynolds number (Re) . The CSF values considered ranged from 0.2 for flaky to 1.0 for perfectly spherical grains and Reynolds numbers from 2.0 to 105 for the laminar to turbulent flow regimes. The specific gravity of submerged particles was optically derived and used along with these parameters to estimate the sediment settling velocity. Comparison with the experiment data showed that the present model estimated settling velocities of spherical and non-spherical particles that were closely consistent with the measured values. Findings revealed that for a given D50, the flaky particles caused a greater decrease in settling velocity than the spherical particles which suggests that the particle shape factor has a profound role in influencing the sediment settling velocity and drag coefficients, especially in transitional and turbulent flow regimes. The present model can

  5. Effects of composition of labile organic matter on biogenic production of methane in the coastal sediments of the Arabian Sea.

    Science.gov (United States)

    Gonsalves, Maria-Judith; Fernandes, Christabelle E G; Fernandes, Sheryl Oliveira; Kirchman, David L; Bharathi, P A Loka

    2011-11-01

    Coastal regions are potential zones for production of methane which could be governed by ecological/environmental differences or even sediment properties of a niche. In order to test the hypothesis that methanogenesis in most marine sediments could be driven more by proteins than by carbohydrates and lipid content of labile organic matter (LOM), incubation experiments were carried out with sediments from different environmental niches to measure methane production. The methane production rates were examined in relationship to the sediment biochemistry, i.e., carbohydrates, proteins, and lipids. The gas production measured by head space method ranged from 216 ng g( -1) day( -1) in the mangrove sediments to 3.1 μg g( -1) day( -1) in the shallow Arabian Sea. LOM ranged from 1.56 to 2.85 mg g( -1) in the shallow Arabian Sea, from 3.35 to 5.43 mg g( -1) in the mangrove estuary, and from 0.66 to 0.70 mg g( -1) in the sandy sediments with proteins contributing maximum to the LOM pool. Proteins influenced methane production in the clayey sediments of shallow depths of the Arabian Sea (r = 0.933, p methane production. The gas production was more pronounced in shallow and surface sediments and it decreased with depth apparently governed by the decrease in lability index. Thus, the lability index and protein content are important factors that determine methane production rates in these coastal ecosystems.

  6. Polycyclic aromatic hydrocarbons (PAHs) in continental shelf sediment of China: Implications for anthropogenic influences on coastal marine environment

    International Nuclear Information System (INIS)

    Liu Liangying; Wang Jizhong; Wei Gaoling; Guan Yufeng; Zeng, Eddy Y.

    2012-01-01

    Sediments collected from the continental shelf of China, embracing Yellow Sea, inner shelf of the East China Sea (ECS), and the South China Sea (SCS), were analyzed for polycyclic aromatic hydrocarbons (PAHs). The concentrations of anthropogenic PAHs (Σ 18 PAH) were 27–224 ng/g dry weight, with an average of 82 ng/g. Sedimentary PAHs in the continental shelf off China were mainly derived from mixed residues of biomass, coal, and petroleum combustion. Fluvial transport and atmospheric deposition mainly accounted for sediment PAHs in the ECS inner shelf and Yellow Sea (and the SCS), respectively. Furthermore, statistically higher levels of Σ 18 PAH (28–224 ng/g; mean 110 ng/g) in the Yellow Sea sediment than in the SCS sediment (28–109 ng/g; mean 58 ng/g) were probably resulted from higher PAH emissions from coke industry and domestic coal combustion in North China than in South China. - Highlights: ► Coal and biomass combustion was the main origin of PAHs in coastal marine sediment of China. ► Fluvial transport was the main mode for transporting PAHs to the East China Sea inner shelf. ► Atmospheric deposition largely accounted for sediment PAHs in Yellow Sea and the South China Sea. ► Regional energy use pattern in China was responsible for the spatial distribution of PAHs in coastal marine sediment. - Sources, compositions and spatial distributions of PAHs in continental shelf sediments off China are analyzed to estimate anthropogenic influences.

  7. Application of Nuclear Techniques for the Study of Sediment Geochronology in Coastal Waters of Location Tread NPP Ujung Lemahabang, Muria Peninsula

    International Nuclear Information System (INIS)

    Heni Susiati; Yarianto SBS; Fepriadi; Sarmin; Lubis, Ali Arman

    2008-01-01

    This investigation of geochronology of eight sediment cores, collected from Muria peninsula coastal has been carried out using natural radionuclide 210 Pb as a tracer through the sediment accumulation profile of unsupported 210 Pb. Sediment sample were collected using gravity core from 8 locations in Muria Peninsula coastal area. Sample was prepared and then analyzed using alpha spectrometer. The result of unsupported 210 Pb analysis shows that at stations with the depth of 19 - 28 em the sediment are 96 - 128 year old. (author)

  8. Mössbauer spectroscopic studies on the iron forms of deep-sea sediments

    Science.gov (United States)

    Drodt, M.; Trautwein, A. X.; König, I.; Suess, E.; Koch, C. Bender

    Mössbauer spectroscopy was applied to characterize the valence states Fe(II) and Fe(III) in sedimentary minerals from a core of the Peru Basin. The procedure in unraveling this information includes temperature-dependent measurements from 275 K to very low temperature (300 mK) in zero-field and also at 4.2 K in an applied field (up to 6.2 T) and by mathematical procedures (least-squares fits and spectral simulations) in order to resolve individual spectral components. The depth distribution of the amount of Fe(II) is about 11% of the total Fe to a depth of 19 cm with a subsequent steep increase (within 3 cm) to about 37%, after which it remains constant to the lower end of the sediment core (at about 40 cm). The steep increase of the amount of Fe(II) defines a redox boundary which coincides with the position where the tan/green color transition of the sediment occurs. The isomer shifts and quadrupole splittings of Fe(II) and Fe(III) in the sediment are consistent with hexacoordination by oxygen or hydroxide ligands as in oxide and silicate minerals. Goethite and traces of hematite are observed only above the redox boundary, with a linear gradient extending from about 20% of the total Fe close to the sediment surface to about zero at the redox boundary. The superparamagnetic relaxation behavior allows to estimate the order of magnitude for the size of the largest goethite and hematite particles within the particle-site distribution, e.g. 170 Å and 50 Å, respectively. The composition of the sediment spectra recorded at 300 mK in zero-field, apart from the contributions due to goethite and hematite, resembles that of the sheet silicates smectite, illite and chlorite, which have been identified as major constituents of the sediment in the clay-mineral iron is redox sensitive. It is proposed that the color change of the sediment at the redox boundary from tan to green is related to the increase of Fe(II)-Fe(III) pairs in the layer silicates, because of the

  9. Reconstruction of metal pollution and recent sedimentation processes in Havana Bay (Cuba): A tool for coastal ecosystem management

    International Nuclear Information System (INIS)

    Díaz-Asencio, M.; Alvarado, J.A. Corcho; Alonso-Hernández, C.; Quejido-Cabezas, A.; Ruiz-Fernández, A.C.; Sanchez-Sanchez, M.; Gómez-Mancebo, M.B.; Froidevaux, P.; Sanchez-Cabeza, J.A.

    2011-01-01

    Highlights: ► Past metal pollution in the heavy polluted coastal ecosystem of Havana Bay. ► Effectiveness of pollution-reduction strategies. ► Dated environmental archives to reconstruct sedimentation and pollution trends. ► Impact of severe climatic events on sedimentation. - Abstract: Since 1998 the highly polluted Havana Bay ecosystem has been the subject of a mitigation program. In order to determine whether pollution-reduction strategies were effective, we have evaluated the historical trends of pollution recorded in sediments of the Bay. A sediment core was dated radiometrically using natural and artificial fallout radionuclides. An irregularity in the 210 Pb record was caused by an episode of accelerated sedimentation. This episode was dated to occur in 1982, a year coincident with the heaviest rains reported in Havana over the XX century. Peaks of mass accumulation rates (MAR) were associated with hurricanes and intensive rains. In the past 60 years, these maxima are related to strong El Niño periods, which are known to increase rainfall in the north Caribbean region. We observed a steady increase of pollution (mainly Pb, Zn, Sn, and Hg) since the beginning of the century to the mid 90s, with enrichment factors as high as 6. MAR and pollution decreased rapidly after the mid 90s, although some trace metal levels remain high. This reduction was due to the integrated coastal zone management program introduced in the late 90s, which dismissed catchment erosion and pollution.

  10. Anaerobic Methane-Oxidizing Microbial Community in a Coastal Marine Sediment: Anaerobic Methanotrophy Dominated by ANME-3.

    Science.gov (United States)

    Bhattarai, Susma; Cassarini, Chiara; Gonzalez-Gil, Graciela; Egger, Matthias; Slomp, Caroline P; Zhang, Yu; Esposito, Giovanni; Lens, Piet N L

    2017-10-01

    The microbial community inhabiting the shallow sulfate-methane transition zone in coastal sediments from marine Lake Grevelingen (The Netherlands) was characterized, and the ability of the microorganisms to carry out anaerobic oxidation of methane coupled to sulfate reduction was assessed in activity tests. In vitro activity tests of the sediment with methane and sulfate demonstrated sulfide production coupled to the simultaneous consumption of sulfate and methane at approximately equimolar ratios over a period of 150 days. The maximum sulfate reduction rate was 5 μmol sulfate per gram dry weight per day during the incubation period. Diverse archaeal and bacterial clades were retrieved from the sediment with the majority of them clustered with Euryarchaeota, Thaumarcheota, Bacteroidetes, and Proteobacteria. The 16S rRNA gene sequence analysis showed that the sediment from marine Lake Grevelingen contained anaerobic methanotrophic Archaea (ANME) and methanogens as archaeal clades with a role in the methane cycling. ANME at the studied site mainly belong to the ANME-3 clade. This study provides one of the few reports for the presence of ANME-3 in a shallow coastal sediment. Sulfate-reducing bacteria from Desulfobulbus clades were found among the sulfate reducers, however, with very low relative abundance. Desulfobulbus has previously been commonly found associated with ANME, whereas in our study, ANME-3 and Desulfobulbus were not observed simultaneously in clusters, suggesting the possibility of independent AOM by ANME-3.

  11. Tracing the anthropogenic lead sources in coastal sediments of SE-Pacific (36 deg. Lat. S) using stable lead isotopes

    International Nuclear Information System (INIS)

    Munoz, Praxedes N.V.; Garbe-Schoenberg, Carl-Dieter; Salamanca, Marco A.

    2004-01-01

    This study evaluates the main sources of antropogenic Pb in one of the most industrialized centers of the southern Chilean coast (36 deg. S). Stable lead isotopes ( 206 Pb/ 207 Pb, 208 Pb/ 207 Pb) were used to trace main Pb sources to coastal sediments, considering the suspended particulate matter (SPM) from marine (traps), continental (rivers) and industrial effluents, sediments and leaded gasoline samples. The atmospheric input was evaluated through natural collectors; i.e. Raqui-Tubul salt marsh. Results show that marine samples lie on a trend between industrial effluents (∼1.16, 2.44) and natural sources (1.20, 2.50), not related to gasoline consumption. Salt marsh sediments show comparable isotopic composition to marine samples, suggesting the importance of the atmospheric input in the coastal sediments, not related to the leaded gasoline composition either. The continental input (1.18, 2.48) is highly influenced by precipitation, being difficult to separate both sources (atmosphere and continental runoff), showing also similar isotopic ratio to marine sediments. The signal of industrial emissions is masked with the introduction of Pb with higher isotopic ratios, compared to the values observed in the material collected from traps (SPM ∼1.19, 2.48). The contribution of more radiogenic Pb by the upwelling is suggested

  12. Radiochronology of marine sediments and its application to the knowledge of the process of environmental pollution in coastal Cuban ecosystems

    International Nuclear Information System (INIS)

    Alonso-Hernández, Carlos M.; Díaz-Asencio, Misael; Gómez-Batista, Miguel; Bolaños-Alvares, Yoelvis; Muñoz-Caravaca, Alain; Morera-Gómez, Yasser

    2016-01-01

    The results achieved in the implementation of the radiochronology of marine sediments for the reconstruction of databases and knowledge of the evolution of environmental pollution in four coastal ecosystems of national significance are presented in this paper Fluxes of selected heavy metals and persistent organic compounds are discussed for the Cienfuegos and Havana bays and Sagua and La Coloma estuaries. Finally, is showed the effectiveness of radiochronology of sediments as a useful tool for environmental management and knowledge of temporal processes of pollution in the aquatic environment. (author)

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

    Digital Repository Service at National Institute of Oceanography (India)

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

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

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

    Science.gov (United States)

    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.

  15. Comprehensive large-scale investigation and assessment of trace metal in the coastal sediments of Bohai Sea.

    Science.gov (United States)

    Li, Hongjun; Gao, Xuelu; Gu, Yanbin; Wang, Ruirui; Xie, Pengfei; Liang, Miao; Ming, Hongxia; Su, Jie

    2018-04-01

    The Bohai Sea is characterized as a semi-closed sea with limited water exchange ability, which has been regarded as one of the most contaminated regions in China and has attracted public attention over the past decades. In recent years, the rapid industrialization and urbanization around the coastal region has resulted in a severe pollution pressure in the Bohai Sea. Although efforts from official government and scientific experts have been made to protect and restore the marine ecosystem, satisfactory achievements were not gained. Moreover, partial coastal areas in the Bohai Sea seemingly remain heavily polluted. In this study, we focused on five coastal regions around the Bohai Sea to study the spatial distribution pattern of trace elements in the sediments and their ecological risk. A total of 108 sediment samples were analyzed to determine the contamination degree of trace elements (Cu, Cd, As, Pb, Zn, Cr, and Hg). Contamination factor (CF), pollution load index (PLI), geoaccumulation index (I geo ), and potential ecological risk index (PERI) were utilized to assess the pollution extent of these metals. Spatial distribution patterns revealed that the sedimentary environments of coastal Bohai were in good condition, except Jinzhou Bay, according to the Marine Sediment Quality of China. The concentrations of Hg and Cd were considerably higher than the average upper crust value and presented high potential ecological risk and considerable potential ecological risk, respectively. The overall environment quality of the coastal Bohai Sea does not seem to pose an extremely serious threat in terms of metal pollution. Thus, the government should continue implementing pollution control programs in the Bohai Sea. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Polycyclic aromatic hydrocarbons in suspended particulate matter and sediments from the Pearl River Estuary and adjacent coastal areas, China

    International Nuclear Information System (INIS)

    Luo Xiaojun; Chen Shejun; Mai Bixian; Yang Qingshu; Sheng Guoying; Fu Jiamo

    2006-01-01

    The spatial distribution, composition, and sources of polycyclic aromatic hydrocarbons (PAHs) in sediments and suspended particulate matter (SPM) from the Pearl River Estuary and adjacent coastal areas were examined. Total PAH concentrations varied from 189 to 637 ng/g in sediments and 422 to 1850 ng/g in SPM. PAHs were dominated by 5,6-ring compounds in sediments and by 2,3-ring compounds in SPM samples. Assessment of PAH sources suggested that biomass and coal combustion is the major PAH source to the outer part of the estuary sediments and that petroleum combustion is the major PAH source to the inner part of estuary sediments. As for SPM samples, PAH isomer pair ratios indicated multiple (petroleum, petroleum combustion, and biomass and coal combustion) PAH sources, and significant temporal variations could exist for the sources of water column PAHs in the study area. The distribution of perylene in SPM samples indicated that the river was the dominant source of perylene in SPM and that perylene could be taken as an index to assess the contribution of river inflow to the total PAHs in SPM samples. The high concentration of perylene in the sediment was indicative of an in situ biogenic origin. - PAH were determined in suspended particulate matter and sediments from Pearl River Estuary

  17. Organic matter composition in the sediment of three Brazilian coastal lagoons: district of Macaé, Rio de Janeiro (Brazil)

    OpenAIRE

    Zink,Klaus-Gerhard; Furtado,André L. S.; Casper,Peter; Schwark,Lorenz

    2004-01-01

    Freshwater lagoons comprise important coastal ecosystems and natural buffers between urbanized land areas and open ocean in the Rio de Janeiro State, Brazil. Studies of sediment and water chemistry, zooplankton and bacterial communities to assess the extent of anthropogenic disturbance are available. Here we contribute with an organic-geochemical approach supplemented by some microbiological aspects to complete the characterization of these lagoonal ecosystems. Bulk organic matter and extract...

  18. The Preliminary Study of Organochlorine Pesticide Residues on Sediments of Bivalvia Fishing Ground at Eastern Part of Coastal Semarang

    Science.gov (United States)

    Adhi Suryono, Chrisna; Subagyo; Setyati, Wilis Ari; Sri Susilo, Endang; Rochaddi, Baskoro; Triaji Mahendrajaya, Robertus

    2018-02-01

    This paper presents the occurrence level of organochlorine contamination in marine sediments of Semarang coastal areas as a fishing ground of Bivalvia. Five compounds (Heptachlor, Aldrin, Endosulfan, Endrin and pp-DDT) of contaminant have been determined in the sediments surface of Semarang coastal waters. The samples were then analyzed by using gas chromatography and followed by using the method of Standard Method Examination. The result showed that the average concentration of organochlorine pesticides Heptachlor, Aldrin, Endosulfan, Endrin and pp-DDT were 25.5, bellow detected, 7.1, 37.2, 28.6 μ g/L, respectively. The high concentration of pesticide showed on Endrin (65,84 ppb), pp-DDT (29,53 μ g/L), and heptachlor (25,45 μ g/L). The low concentrations were detected on aldrin (bellow detected) and endosulfan (0,92 μ g/L). The concentration of organochlorine pesticides in these areas might contribute on four rivers which deposited the sediment in these coastal waters

  19. The mineralogical behavior of the phosphatic sedimentation in Pernambuco-Paraiba sedimentar coastal basin

    International Nuclear Information System (INIS)

    Albuquerque Menor, E. de; Amaral, A.J.R. do

    1979-01-01

    This work reports the execution of the ''Phosphate in the Sedimentary coastal zone of Pernambuco-Paraiba'' Project, resulting from the execution of 35 drilling holes distributed between Paulista City, State of Pernambuco and the Miriri river valley, State of Paraiba. The rocks were analysed by X-ray diffraction, and the results were used in the working up of mineralogical logs. The mineralogical logs interpretation makes possible to distinguish phosphorite and sandy phosphorite areas inside a mineralization zone, wich laterally passes to a phosphatic carbonatic rocks area situated far from cost line of that epoch. Differences of the mineral paragenesis are used under a regional sedimentar model conception and indicated as prospecting guides. The dominance of Kaolinite is related to continental sediments (Beberibe Formation). The dominance of montmorillonite, on the other hand, is more to marine facies than to particular conditions of the phosphatic mineralization. The analysis of these conditions shows that the continental areas resistant to the pre-Maestrichtrian transegressive oscillations coincide to the more favourable places to the phosphatic mineralization. (author) [pt

  20. Nitrogen Fixation By Sulfate-Reducing Bacteria in Coastal and Deep-Sea Sediments

    Science.gov (United States)

    Bertics, V. J.; Löscher, C.; Salonen, I.; Schmitz-Streit, R.; Lavik, G.; Kuypers, M. M.; Treude, T.

    2011-12-01

    Sulfate-reducing bacteria (SRB) can greatly impact benthic nitrogen (N) cycling, by for instance inhibiting coupled denitrification-nitrification through the production of sulfide or by increasing the availability of fixed N in the sediment via dinitrogen (N2)-fixation. Here, we explored several coastal and deep-sea benthic habitats within the Atlantic Ocean and Baltic Sea, for the occurrence of N2-fixation mediated by SRB. A combination of different methods including microbial rate measurements of N2-fixation and sulfate reduction, geochemical analyses (porewater nutrient profiles, mass spectrometry), and molecular analyses (CARD-FISH, HISH-SIMS, "nested" PCR, and QPCR) were applied to quantify and identify the responsible processes and organisms, respectively. Furthermore, we looked deeper into the question of whether the observed nitrogenase activity was associated with the final incorporation of N into microbial biomass or whether the enzyme activity served another purpose. At the AGU Fall Meeting, we will present and compare data from numerous stations with different water depths, temperatures, and latitudes, as well as differences in key geochemical parameters, such as organic carbon content and oxygen availability. Current metabolic and molecular data indicate that N2-fixation is occurring in many of these benthic environments and that a large part of this activity may linked to SRB.

  1. Bacterial communities potentially involved in iron-cycling in Baltic Sea and North Sea sediments revealed by pyrosequencing

    DEFF Research Database (Denmark)

    Reyes, Carlen; Dellwig, Olaf; Dähnke, K.

    2016-01-01

    To gain insight into the bacterial communities involved in iron-(Fe) cycling under marine conditions, we analysed sediments with Fe-contents (0.5-1.5 wt %) from the suboxic zone at a marine site in the Skagerrak (SK) and a brackish site in the Bothnian Bay (BB) using 16S rRNA gene pyrosequencing....

  2. Impact of Sediment-Bound Iron on Redox Buffering in a Landfill Leachate Polluted Aquifer (Vejen, Denmark)

    DEFF Research Database (Denmark)

    Heron, Gorm; Christensen, Thomas Højlund

    1995-01-01

    Sediments sampled along a central flow line of the leachate pollution plume at the Vejen Landfill, Denmark, were characterized in detail with respect to the forms and pools of Fe(ll) and Fe(lll). After 15 yr of leaching, redox reactions had diminished the pool of iron(ll1) oxides and hydroxides...

  3. Marine organic geochemistry in industrially affected coastal areas in Greece: Hydrocarbons in surface sediments

    Science.gov (United States)

    Hatzianestis, Ioannis

    2015-04-01

    Hydrocarbons are abundant components of the organic material in coastal zones. Their sources are mainly anthropogenic, but several natural ones have also been recognized. Among hydrocarbons, the polycyclic aromatic ones (PAHs) have received special attention since they considered as hazardous environmental chemicals and are included in priority pollutant lists. The purpose of this study was to investigate the distribution, sources and transport pathways of hydrocarbons in marine areas in Greece directly influenced from the operation of major industrial units in the coastal zone by using a molecular marker approach, characteristic compositional patterns and related indices and also to evaluate their potential toxicity. Thirty two surface sediment samples were collected from three marine areas: a) Antikyra bay in Korinthiakos gulf, affected from the operation of an alumina and production plant b) Larymna bay in Noth Evoikos, affected from the operation of a nickel production plant and c) Aliveri bay in South Evoikos Gulf, affected from a cement production plant. In all the studied areas aquaculture and fishing activities have been also developed in the coastal zone. High aliphatic hydrocarbon (AHC) concentrations (~500 μg/g), indicating significant petroleum related inputs, were measured only in Antikyra bay. In all the other samples, AHC values were below 100 μg/g. N-alkanes were the most prominent resolved components (R) with an elevated odd to even carbon number preference, revealing the high importance of terrestrial inputs in the study areas. The unresolved complex mixture (UCM) was the major component of the aliphatic fraction (UCM/R > 4), indicating a chronic oil pollution. A series of hopanes were also identified, with patterns characteristic of oil-derived hydrocarbons, further confirming the presence of pollutant inputs from fossil fuel products. Extremely high PAH concentrations (> 100,000 ng/g) were found in the close vicinity of the alumina production

  4. Integrative assessment of coastal pollution: Development and evaluation of sediment quality criteria from chemical contamination and ecotoxicological data

    Science.gov (United States)

    Bellas, Juan; Nieto, Óscar; Beiras, Ricardo

    2011-04-01

    Elutriate embryo-larval bioassays with sea-urchins ( Paracentrotus lividus) were conducted concurrently with chemical analyses of sediments and biota as part of an integrative assessment of pollution in highly productive coastal regions. High metal contents and organic compounds in sediments and mussels were found in localised areas from the inner part of the estuaries indicating a clear anthropogenic influence. In particular, average maximum concentrations of 2803 mg Cu/kg dw, 776 mg Pb/kg dw, 2.5 mg Hg/kg dw and 5803 μg ∑ 7PAHs/kg dw were measured in sediments from the most polluted sites. Significant correlations were observed between sediment chemistry and toxicity bioassays. Moreover, the Mantel test revealed a significant correlation ( rM=0.80; pbioassays identified polluted sites and quantified the level of toxicity, providing a cost-effective tool to complement the routine chemical monitoring currently conducted in European coastal waters with ecologically relevant information. This is in line with the recent European legislation that advocates the use of biological tools with the ultimate aim of protecting marine resources from anthropogenic substances that will affect their sensitive early life stages.

  5. Mercury profiles in sediments of the Pearl River Estuary and the surrounding coastal area of South China

    International Nuclear Information System (INIS)

    Shi Jianbo; Ip, Carman C.M.; Zhang Gan; Jiang Guibin; Li Xiangdong

    2010-01-01

    The spatial and temporal variations of mercury (Hg) in sediments of the Pearl River Estuary (PRE) and the surrounding coastal area (South China Sea) were studied. In surface sediments, the concentrations of Hg ranged from 1.5 to 201 ng/g, with an average of 54.4 ng/g, displaying a decreasing trend with the distance from the estuary to the open sea. This pattern indicates that the anthropogenic emissions from the Pearl River Delta (PRD) region are probably the main sources of Hg in this coastal region. Using the 210 Pb dating technique, the historical changes in the concentrations and influxes of Hg in the last 100 years were also investigated. The variations in Hg influxes in sediment cores obviously correlate with the economic development and urbanization that has occurred the PRD region, especially in the last three decades. - The spatial and historical changes of Hg in sediment reflect the industrial development and urbanization of the region in south China.

  6. Patterns and controls of mercury accumulation in sediments from three thermokarst lakes on the Arctic Coastal Plain of Alaska

    Science.gov (United States)

    Burke, Samantha M.; Zimmerman, Christian E.; Branfireun, Brian A.; Koch, Joshua C.; Swanson, Heidi K.

    2018-01-01

    The biogeochemical cycle of mercury will be influenced by climate change, particularly at higher latitudes. Investigations of historical mercury accumulation in lake sediments inform future predictions as to how climate change might affect mercury biogeochemistry; however, in regions with a paucity of data, such as the thermokarst-rich Arctic Coastal Plain of Alaska (ACP), the trajectory of mercury accumulation in lake sediments is particularly uncertain. Sediment cores from three thermokarst lakes on the ACP were analyzed to understand changes in, and drivers of, Hg accumulation over the past ~ 100 years. Mercury accumulation in two of the three lakes was variable and high over the past century (91.96 and 78.6 µg/m2/year), and largely controlled by sedimentation rate. Mercury accumulation in the third lake was lower (14.2 µg/m2/year), more temporally uniform, and was more strongly related to sediment Hg concentration than sedimentation rate. Sediment mercury concentrations were quantitatively related to measures of sediment composition and VRS-inferred chlorophyll a, and sedimentation rates were related to various catchment characteristics. These results were compared to data from 37 previously studied Arctic and Alaskan lakes. Results from the meta-analysis indicate that thermokarst lakes have significantly higher and more variable Hg accumulation rates than non-thermokarst lakes, suggesting that certain properties (e.g., thermal erosion, thaw slumping, low hydraulic conductivity) likely make lakes prone to high and variable Hg accumulation rates. Differences and high variability in Hg accumulation among high latitude lakes highlight the complexity of predicting future climate-related change impacts on mercury cycling in these environments.

  7. Impact of mussel bioengineering on fine-grained sediment dynamics in a coastal lagoon: a numerical modelling investigation

    DEFF Research Database (Denmark)

    Forsberg, Pernille Louise; Lumborg, Ulrik; Bundgaard, Klavs

    2017-01-01

    Rødsand lagoon in southeast Denmark is a non-tidal coastal lagoon. It is home to a wide range of marine flora and fauna and part of the Natura 2000 network. An increase in turbidity through elevated levels of suspended sediment concentration (SSC) within the lagoon may affect the ecosystem health...... due to reduced light penetration. Increasing SSC levels within Rødsand lagoon could be caused by increasing storm intensity or by a sediment spill from dredging activities west of the lagoon in relation to the planned construction of the Fehmarnbelt fixed link between Denmark and Germany. The aim...... of the study was to investigate the impact of a mussel reef on sediment import and SSC in a semi-enclosed lagoon through the development of a bioengineering modelling application that makes it possible to include the filtrating effect of mussels in a numerical model of the lagoonal system. The numerical...

  8. Modern sedimentation processes in a wave-dominated coastal embayment: Espírito Santo Bay, southeast Brazil

    Science.gov (United States)

    Bastos, Alex Cardoso; Costa Moscon, Daphnne Moraes; Carmo, Dannilo; Neto, José Antonio Baptista; da Silva Quaresma, Valéria

    2015-02-01

    Sediment dynamics in wave-dominated coastal embayments are generally controlled by seasonal meteorological conditions, storms having a particularly strong influence. In the present study, such hydrodynamic processes and associated deposits have been investigated in a coastal embayment located along the southeast coast of Brazil, i.e. Espírito Santo Bay, in the winter (June/July) of 2008. The bay has undergone a series of human interventions that have altered the local hydrodynamic processes and, consequently, the sediment transport patterns. Facies distribution and sediment dynamics were examined by acoustic seabed mapping, sediment and core sampling, hydrodynamic measurements and sand transport modelling. The results show that sediment distribution can be described in terms of nearshore and offshore zones. The offshore bay sector is predominantly composed of "palimpsest" lithoclastic medium-coarse sands deposited in the course of the early Holocene transgression that peaked about 5,000 years ago. In the inner bay or nearshore zone (up to depths of 4-8 m), these older transgressive deposits are today overlain by a thin (up to 30-cm-thick) and partly patchy blanket of younger regressive fine sand/muddy fine sands. Both coarse- and fine-grained facies are being reworked during high-energy events (Hs>1.5 m) when fine sediment is resuspended, weak tide-induced drift currents causing the sand patches to be displaced. The coarser sediment, by contrast, is mobilized as bedload to produce wave ripples with spacings of up to 1.2 m. These processes lead to a sharp spatial delimitation between a fine sand/mud facies and a rippled coarse sand facies. The fine sand patches have a relief of about 20-30 cm and reveal a typical internal tempestite depositional sequence. Fair-weather wave-induced sediment transport (Hs<1 m), supported by weak tidal currents, seems to only affect the fine sediment facies. Sediment dynamics in Espírito Santo Bay is thus essentially controlled by

  9. Studies of iron in deep-sea sediments by Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Drodt, M.; Lougear, A.; Trautwein, A.X.; Koenig, I.; Suess, E.; Koch, C. Bender

    1998-01-01

    The distribution of the forms of Fe in the solid phases in core samples of sediments from the Peru Basin has been investigated by Moessbauer spectroscopy with special attention to the cause of the sharp color transition between an upper green colored and a lower tan colored part. An important part of sample handling includes strict exclusion of oxygen during preparation of absorbers and measurements at cryogenic temperatures. The measurement strategy includes measurements between 77 K and 300 mK in zero external magnetic field, supplemented by measurements in external magnetic fields at 4.2 and 300 mK (up to 6.2 and 1 T, respectively). The temperature scans allow detection, identification and quantification of superparamagnetic iron oxides (goethite and hematite). The oxides are only present in samples from the upper tan-colored part of the core. The major part of the Fe(II) and Fe(III) (>80%) is present in a magnetic structure similar to that of layer silicates. The relative Fe(II) content of the layer silicates is practically identical to that determined from the paramagnetic components measured at liquid nitrogen temperature. This shows that the color transition in the sediment coincides with a change in the relative Fe(II) content in layer silicates from 11 to 37%. The color change can thus be explained by an increase in occurrence of Fe(II)-Fe(III) pairs exhibiting absorption bands due to intervalence electron transfer

  10. Thiosulfate and sulfite distributions in porewater of marine sediments related to manganese, iron, and sulfur geochemistry

    Science.gov (United States)

    Thamdrup, Bo; Finster, Kai; Fossing, Henrik; Hansen, Jens Würgler; Jørgensen, Bo Barker

    1994-01-01

    Depth distributions of thiosulfate (S 2O 32-) and sulfite (SO 32-) were measured in the porewaters of a Danish salt marsh and subtidal marine sediments by HPLC analysis after derivatization with DTNP [2,2'-dithiobis(5-nitropyridine)]. The distributions were compared to the redox zonation as indicated by Eh and Mn 2+, Fe 2+ and H 2S distributions. Concentrations of S 2O 32- varied from below detection (<50 nM) to 600 nM while SO 32- concentrations generally were 2-3 times higher, 100-1500 nM. Depth distributions of the two species were roughly similar. Lowest concentrations were found in the oxidized zone, including both the oxic surface layer and the suboxic zone of intense manganese and iron reduction, and concentrations tended to increase through the suboxic and into the reduced, sulfidic zone. The similarity of SO 32- and S 2O 32- profiles suggested a close coupling of the cycling of the two species. Rates of consumption were suggested as the main factor governing their distribution. Rapid turnover times for S 2O 32- and H 2S of 4 and 1.1 h, respectively, were estimated for the upper 0-1 cm of a subtidal sediment.

  11. Iron

    Science.gov (United States)

    Iron is a mineral that our bodies need for many functions. For example, iron is part of hemoglobin, a protein which carries ... It helps our muscles store and use oxygen. Iron is also part of many other proteins and ...

  12. Benthic iron and phosphorus release from river dominated shelf sediments under varying bottom water O2 concentrations.

    Science.gov (United States)

    Ghaisas, N. A.; Maiti, K.; White, J. R.

    2017-12-01

    Phosphorus (P) cycling in coastal ocean is predominantly controlled by river discharge and biogeochemistry of the sediments. In coastal Louisiana, sediment biogeochemistry is strongly influenced by seasonally fluctuating bottom water O2, which, in turn transitions the shelf sediments from being a sink to source of P. Sediment P-fluxes were 9.73 ± 0.76 mg / m2 /d and 0.67±0.16 mg/m2/d under anaerobic and aerobic conditions respectively, indicating a 14 times higher P-efflux from oxygen deprived sediments. A high sedimentary oxygen consumption rate of 889 ± 33.6 mg/m2/d was due to organic matter re-mineralization and resulted in progressively decreasing the water column dissolved O2 , coincident with a P-flux of 7.2 ± 5.5 mg/m2/d from the sediment. Corresponding water column flux of Fe total was 19.7 ± 7.80 mg/m2/d and the sediment-TP decreased from 545 mg/Kg to 513 mg/Kg. A simultaneous increase in pore water Fe and P concentrations in tandem with a 34.6% loss in sedimentary Fe-bound P underscores the importance of O2 on coupled Fe- P biogeochemistry. This study suggests that from a 14,025 sq. km hypoxia area, Louisiana shelf sediments can supply 1.33x105 kg P/day into the water column compared to 0.094 x 105 kg P/day during the fully aerobic water column conditions.

  13. Depositional record of trace metals and degree of contamination in core sediments from the Mandovi estuarine mangrove ecosystem, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Veerasingam, S.; Vethamony, P.; ManiMurali, R.; Fernandes, B.

    of sources. Enrichment of metals in bottom sediments represents a critical measure of health for any mangrove ecosystem (Janaki-Raman et al., 2007). Trace metals in coastal and estuarine sediments are incorporated into the aquatic food webs through primary... of susceptibility of the particles to the processes of physical and chemical weathering. The different morphological forms of iron oxides are well correlated with the sediment horizons. Spherical iron oxides predominate in the upper layers of sediment profiles...

  14. Spatially Resolving Ocean Color and Sediment Dispersion in River Plumes, Coastal Systems, and Continental Shelf Waters

    Science.gov (United States)

    Aurin, Dirk Alexander; Mannino, Antonio; Franz, Bryan

    2013-01-01

    Satellite remote sensing of ocean color in dynamic coastal, inland, and nearshorewaters is impeded by high variability in optical constituents, demands specialized atmospheric correction, and is limited by instrument sensitivity. To accurately detect dispersion of bio-optical properties, remote sensors require ample signal-to-noise ratio (SNR) to sense small variations in ocean color without saturating over bright pixels, an atmospheric correction that can accommodate significantwater-leaving radiance in the near infrared (NIR), and spatial and temporal resolution that coincides with the scales of variability in the environment. Several current and historic space-borne sensors have met these requirements with success in the open ocean, but are not optimized for highly red-reflective and heterogeneous waters such as those found near river outflows or in the presence of sediment resuspension. Here we apply analytical approaches for determining optimal spatial resolution, dominant spatial scales of variability ("patches"), and proportions of patch variability that can be resolved from four river plumes around the world between 2008 and 2011. An offshore region in the Sargasso Sea is analyzed for comparison. A method is presented for processing Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua and Terra imagery including cloud detection, stray lightmasking, faulty detector avoidance, and dynamic aerosol correction using short-wave- and near-infrared wavebands in extremely turbid regions which pose distinct optical and technical challenges. Results showthat a pixel size of approx. 520 mor smaller is generally required to resolve spatial heterogeneity in ocean color and total suspended materials in river plumes. Optimal pixel size increases with distance from shore to approx. 630 m in nearshore regions, approx 750 m on the continental shelf, and approx. 1350 m in the open ocean. Greater than 90% of the optical variability within plume regions is resolvable with

  15. Antibiotic resistance of Vibrio parahaemolyticus isolated from coastal seawater and sediment in Malaysia

    Science.gov (United States)

    Drais, Ashraf Abbas; Usup, Gires; Ahmad, Asmat

    2016-11-01

    Vibrio parahaemolyticus is widely recognized pathogenic Vibrio species due to numerous outbreaks and its' wide occurrence in the marine environment. A total of 50 Vibrio parahaemolyticus isolates were isolated from seawater and sediments in Malaysia were tested for sensitivity to 19 antibiotics using disc diffusion method. It was found that all isolates were resistant towards ampicillin (10 μg), penicillin (10 μg), methicillin (5 μg), and novobiocin (5 μg); but exhibit sensitivity to chloramphenicol (30 μg) and gentamicin (100 μg). The low percentage of sensitivity towards antibiotics was observed with the following antibiotics; amoxicillin 10μg (98%), fluconazole 25μg (98%), erythromycin 15 μg (92%), vancomycin 30 μg (92%), bacitracin 10 μg (84%), carbenicillin 100 μg (84%), cephalothin 30 μg (52%), nitrofurantion 200 μg (52%), ciprofloxacin 5 μg (40%), tetracycline 30 μg (20%), kanamycin 30 μg (10%), nalidixic acid 30 μg (10%) and streptomycin 20 μg (6%). Multiple antibiotic resistance (MAR) index was found to be 0.42-0.78. All the isolates were multi-resistant to these antibiotics. This indicates that the isolates originate from high-risk source of contamination where antibiotics are often used. Thus, there is a need for supervised use of antibiotics and frequent surveillance of V. parahaemolyticus strains for antimicrobial resistance. The presence of V. parahaemolyticus in coastal water with a high value of multiple antibiotic resistance indexes (MARI) can increase the risk of exposure to human and regular monitoring program for this potential human pathogenic bacterium is important.

  16. Iron Availability Influences Silicon Isotope Fractionation in Two Southern Ocean Diatoms (Proboscia inermis and Eucampia antarctica and a Coastal Diatom (Thalassiosira pseudonana

    Directory of Open Access Journals (Sweden)

    Scott Meyerink

    2017-07-01

    Full Text Available The fractionation of silicon (Si isotopes was measured in two Southern Ocean diatoms (Proboscia inermis and Eucampia Antarctica and a coastal diatom (Thalassiosira pseudonana that were grown under varying iron (Fe concentrations. Varying Fe concentrations had no effect on the Si isotope enrichment factor (ε in T. pseudonana, whilst E. Antarctica and P. inermis exhibited significant variations in the value of ε between Fe-replete and Fe-limited conditions. Mean ε values in P. inermis and E. Antarctica decreased from (± 1SD −1.11 ± 0.15‰ and −1.42 ± 0.41 ‰ (respectively under Fe-replete conditions, to −1.38 ± 0.27 ‰ and −1.57 ± 0.5 ‰ (respectively under Fe-limiting conditions. These variations likely arise from adaptations in diatoms arising from the nutrient status of their environment. T. pseudonana is a coastal clone typically accustomed to low Si but high Fe conditions whereas E. Antarctica and P. inermis are typically accustomed to High Si, High nitrate low Fe conditions. Growth induced variations in silicic acid (Si(OH4 uptake arising from Fe-limitation is the likely mechanism leading to Si-isotope variability in E. Antarctica and P. inermis. The multiplicative effects of species diversity and resource limitation (e.g., Fe on Si-isotope fractionation in diatoms can potentially alter the Si-isotope composition of diatom opal in diatamaceous sediments and sea surface Si(OH4. This work highlights the need for further in vitro studies into intracellular mechanisms involved in Si(OH4 uptake, and the associated pathways for Si-isotope fractionation in diatoms.

  17. Simulation of land use impacts on sediment and nutrient transfer in coastal areas of Western Cape, South Africa

    Directory of Open Access Journals (Sweden)

    Gebel Micha

    2017-01-01

    Full Text Available A major challenge for water resource management in Western Cape, South Africa, is the reduction of the growing sediment and nutrient loads in coastal areas, which belong to the areas most affected by land use change. We used the WebGIS based software STOFFBILANZ to simulate runoff, soil loss, sediment, phosphorus, and nitrogen input in the surface water and groundwater of study area (ca. 6,450 km². The simulated runoff shows a large regional variability caused by the heterogeneous distribution of rainfall. For the reference catchment Klein River simulated total daily runoff fit the observed values of the reference year 2012. The calculation of potential input of sediment, phosphorus, and nitrogen into waters is based on aggregated or generalized information on climate data, land use types, crop and fruit types, yields, mineral fertilizers, farm manure, nitrogen fixing by leguminous plants, atmospheric nitrogen deposition, and soil denitrification. Critical source areas for potential sediment input, particulate P input and diffuse N input are mainly agricultural areas. Additionally, point sources of high relevance for N and P are found in urban areas. Based on the potential input of sediment and nutrients the impacts of current land use change on water resources were estimated. We used the web-based information system WebLand for the simulation aiming at the provision of stakeholders with information for decision making in water resource management.

  18. Concentration, composition and sources of PAHs in the coastal sediments of the exclusive economic zone (EEZ) of Qatar, Arabian Gulf.

    Science.gov (United States)

    Soliman, Y S; Al Ansari, E M S; Wade, T L

    2014-08-30

    Surface sediments were collected from sixteen locations in order to assess levels and sources of polycyclic aromatic hydrocarbons (PAHs) in sediments of Qatar exclusive economic zone (EEZ). Samples were analyzed for 16 parent PAHs, 18 alkyl homologs and for dibenzothiophenes. Total PAHs concentration (∑PAHs) ranged from 2.6 ng g(-1) to 1025 ng g(-1). The highest PAHs concentrations were in sediments in and adjacent to harbors. Alkylated PAHs predominated most of the sampling locations reaching up to 80% in offshore locations. Parent PAHs and parent high molecular weight PAHs dominated location adjacent to industrial activities and urban areas. The origin of PAHs sources to the sediments was elucidated using ternary plot, indices, and molecular ratios of specific compounds such as (Ant/Phe+Ant), (Flt/Flt+Pyr). PAHs inputs to most coastal sites consisted of mixture of petroleum and combustion derived sources. However, inputs to the offshore sediments were mainly of petroleum origin. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Occurrence of perfluorinated alkyl substances in sediment from estuarine and coastal areas of the East China Sea.

    Science.gov (United States)

    Yan, Hong; Zhang, Chaojie; Zhou, Qi; Yang, Shouye

    2015-02-01

    Perfluorinated alkyl substances (PFAS) have drawn much attention due to their environmental persistence, ubiquitous existence, and bioaccumulation potential. The occurrence and spatial variation of PFAS were investigated through collection of riverine and marine sediments from estuarine and coastal areas of the East China Sea. Among them, perfluorooctanesulfonic acid (PFOS), perfluoroheptanoic acid (PFHpA), and perfluorooctanoic acid (PFOA) were the three predominant PFAS with the highest detection frequencies in the sediment. PFOS up to 32.4 ng g(-1) dw and ∑PFAS up to 34.8 ng g(-1) dw were detected. Compared to other studies, high levels of PFOS were found in sediments from the East China Sea. PFHpA was also detected at higher frequency and concentration than those of other studies, which suggests point sources in this area. Concentrations of PFAS in riverine sediments were much higher than in marine sediments. Analysis of spatial variations presented overall decreasing trends of PFAS from inshore to offshore areas.

  20. Persistent toxic substances in remote lake and coastal sediments from Svalbard, Norwegian Arctic: Levels, sources and fluxes

    International Nuclear Information System (INIS)

    Jiao Liping; Zheng, Gene J.; Minh, Tu Binh; Richardson, Bruce; Chen Liqi; Zhang Yuanhui; Yeung, Leo W.; Lam, James C.W.; Yan, Xulin; Lam, Paul K.S.; Wong, Ming H.

    2009-01-01

    Surface sediments from remote lakes and coastal areas from Ny-Alesund, Svalbard, Norwegian Arctic were analyzed for polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs). Relatively high levels of PAHs were encountered from several lakes from Ny-Alesund, which were within the range of levels reported for European high mountain lakes and some urban/industrialized areas in the world, pointing to the role of remote Arctic lakes as potential reservoir of semi-volatile organic compounds. Specific patterns of PBDEs were observed, showing higher concentrations of lower brominated compounds such as BDE-7, 17 and 28. Estimated surface sediment fluxes of PAHs in Ny-Alesund remote lakes were similar to those observed for some European high mountain lakes. The current PAH levels in sediments from three lakes exceeded Canadian sediment quality guidelines, suggesting the presence of possible risks for aquatic organisms and the need for further studies. - High levels of PAHs and specific patterns of PBDEs were found in sediments from the remote Norwegian Arctic lakes

  1. Metagenomic Analysis of Subtidal Sediments from Polar and Subpolar Coastal Environments Highlights the Relevance of Anaerobic Hydrocarbon Degradation Processes

    Energy Technology Data Exchange (ETDEWEB)

    Espinola, Fernando J.; Dionisi, Hebe M.; Borglin, Sharon; Brislawn, Colin J.; Jansson, Janet K.; Mac Cormack, Walter P.; Carroll, Jolynn; Sjoling, Sara; Lozada , Mariana

    2018-01-02

    In this work, we analyzed the community structure and metabolic potential of sediment microbial communities in high-latitude coastal environments subjected to low to moderate levels of chronic pollution. Subtidal sediments from four low-energy inlets located in polar and subpolar regions from both Hemispheres were analyzed using large-scale 16S rRNA gene and metagenomic sequencing. Communities showed high diversity (Shannon’s index 6.8 to 10.2), with distinct phylogenetic structures (<40% shared taxa at the Phylum level among regions) but similar metabolic potential in terms of sequences assigned to KOs. Environmental factors (mainly salinity, temperature, and in less extent organic pollution) were drivers of both phylogenetic and functional traits. Bacterial taxa correlating with hydrocarbon pollution included families of anaerobic or facultative anaerobic lifestyle, such as Desulfuromonadaceae, Geobacteraceae, and Rhodocyclaceae. In accordance, biomarker genes for anaerobic hydrocarbon degradation (bamA, ebdA, bcrA, and bssA) were prevalent, only outnumbered by alkB, and their sequences were taxonomically binned to the same bacterial groups. BssA-assigned metagenomic sequences showed an extremely wide diversity distributed all along the phylogeny known for this gene, including bssA sensu stricto, nmsA, assA, and other clusters from poorly or not yet described variants. This work increases our understanding of microbial community patterns in cold coastal sediments, and highlights the relevance of anaerobic hydrocarbon degradation processes in subtidal environments.

  2. A Technique For Remote Sensing Of Suspended Sediments And Shallow Coastal Waters Using MODIS Visible and Near-IR Channels

    Science.gov (United States)

    Li, R.; Kaufman, Y.

    2002-12-01

    ABSTRACT We have developed an algorithm to detect suspended sediments and shallow coastal waters using imaging data acquired with the Moderate Resolution Imaging SpectroRadiometer (MODIS). The MODIS instruments on board the NASA Terra and Aqua Spacecrafts are equipped with one set of narrow channels located in a wide 0.4 - 2.5 micron spectral range. These channels were designed primarily for remote sensing of the land surface and atmosphere. We have found that the set of land and cloud channels are also quite useful for remote sensing of the bright coastal waters. We have developed an empirical algorithm, which uses the narrow MODIS channels in this wide spectral range, for identifying areas with suspended sediments in turbid waters and shallow waters with bottom reflections. In our algorithm, we take advantage of the strong water absorption at wavelengths longer than 1 æm that does not allow illumination of sediments in the water or a shallow ocean floor. MODIS data acquired over the east coast of China, west coast of Africa, Arabian Sea, Mississippi Delta, and west coast of Florida are used in this study.

  3. Biodiversity effects of benthic ecosystem engineers on the spatial patterns of sediment CH4 concentration in an urban Neotropical coastal lagoon

    Directory of Open Access Journals (Sweden)

    Adriano Caliman

    Full Text Available AIM: Biodiversity of sediment bioturbators has been shown to be important for to the magnitude and stability of benthic-pelagic processes. However, no study to date has evaluated the importance of the biodiversity of benthic invertebrate bioturbators to the spatial patterns of sediment CH4 concentration ([CH4]. Here we conducted a laboratorial experiment to test the following predictions: (1 Bioturbator species richness will reduce the sediment [CH4]; (2 individual bioturbator species (i.e. species composition will have different effects on sediment [CH4]; (3 and both the effects of bioturbator species richness and composition on sediment [CH4] will be dependent on sediment depth. METHODS: We manipulated the number and composition of three functional divergent benthic invertebrate bioturbators species that are widespread in South Atlantic coastal lagoons, in laboratorial sediment chambers containing the sediment and water of an urban impacted coastal lagoon RESULTS: Bioturbator species richness had no overall significant effect on sediment [CH4] when comparisons of sediment [CH4] were made among species richness levels. However, bioturbator species richness significantly reduced sediment [CH4] when species richness levels were compared to the control (defaunated treatments, but this effect was significant only at the deepest sediment layer. Furthermore, bioturbator species composition had significant, but distinct effects on the patterns of reduction in sediment [CH4], depending on the sediment depth and the bioturbator species. CONCLUSIONS: We conclude that both the number and composition of bioturbator species are important to determine the effects of benthic bioturbators on spatial patterns of sediment [CH4], but the strength of these effects depend on species traits that determine interspecific interactions strength across the sediment vertical niche space.

  4. Spatial variation of PAHs and PCBs in coastal air, seawater, and sediments in a heavily industrialized region.

    Science.gov (United States)

    Odabasi, Mustafa; Dumanoglu, Yetkin; Kara, Melik; Altiok, Hasan; Elbir, Tolga; Bayram, Abdurrahman

    2017-05-01

    Concurrent coastal seawater (n = 22), sediment (n = 22), and atmospheric samples (n = 10) were collected in the Aliaga industrial region, Turkey, to explore the spatial variation, sources, and air-seawater exchange of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Seawater Σ 16 PAH concentrations (particle + dissolved) ranged between 5107 and 294,624 pg L -1 , while Σ 41 PCB concentrations were in the range of 880-50,829 pg L -1 . Levels in sediments were highly variable ranging between 35.5-49,682 and 2.7-2450 μg kg -1 in dry weight for Σ 16 PAHs and Σ 41 PCBs, respectively. Atmospheric concentrations varied between 1791-274,974 and 104-20,083 pg m -3 for Σ 16 PAHs and Σ 41 PCBs, respectively. Sediment organic matter (OM) content and levels of Σ 16 PAHs and Σ 41 PCBs correlated weakly (r 2  = 0.19-0.23, p seawater, and sediment and factor analysis on the sediment levels pointed out that the major sources in the region are steel plants, petroleum refinery, petrochemical complex, ship breaking, loading/unloading activities at the ports, vehicular emissions, and fossil fuel combustion emissions. The direction of the air-seawater exchange was also explored by estimating seawater fugacity fractions of PAHs and PCBs. For PAHs, the number of cases implying deposition (43.0%) and volatilization (39.5%) was similar, while for PCBs, the number of cases implying volatilization (60.4%) was much higher compared to deposition (21.6%). Fugacity fractions were generally seawater and sediment levels were measured, implying that atmospheric deposition is an important mechanism affecting seawater and sediment PAH and PCB levels.

  5. Coastal lagoon sediments and benthic foraminifera as indicator for Holocene sea-level change: Samsø, southern Kattegat

    DEFF Research Database (Denmark)

    Sander, Lasse; Morigi, Caterina; Pejrup, Morten

    The island of Samsø is located in the southern Kattegat region of Denmark, a relatively sheltered micro-tidal environment. The area experienced a period of rapid transgression during the early Altantic period, reaching its maximum approx. 7,600 yr BP. Since then, isostatic uplift gradually caused....... Over time, an extensive beach ridge system formed, which eventually connected the islands, giving Samsø its characteristic shape. Ephemeral shallow-water lagoons evolved in topographic depressions along the shores of the island, most of which became inactive until today. A semi-enclosed coastal lagoon......-level and to investigate associated geomorphic responses in coastal lagoon and beach ridge systems. Vibracorings will be carried out in these sedimentary environments and will be supplemented with manual auger corings and ground penetrating radar (GPR) surveys to assess vertical variations in the deposited sediments...

  6. Flow and Suspended Sediment Events in the Near-Coastal Zone off Corpus Christi, Texas

    Science.gov (United States)

    2003-09-30

    redistribution of preexisting shelf sediments during storms and (2) transportation of suspended sediment from the adjacent bay- lagoon system. Snedden et al...and K.E. Schmedes. (1983). Submerged lands of Texas, Corpus Christi area: sediments, geochemistry, benthic macroinvertebrates and associated

  7. Risk assessment of trace metal-polluted coastal sediments on Hainan Island: A full-scale set of 474 geographical locations covering the entire island.

    Science.gov (United States)

    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.

  8. Sediment dynamics in the coastal areas of Forsmark and Laxemar during an interglacial

    International Nuclear Information System (INIS)

    Brydsten, Lars

    2009-06-01

    Radionuclides dissolved in groundwater that reach the sea bottom from below may bind to fine grained particles. When a nuclide binds to an immovable particle in the sea sediment, further transport may cease; however, if the nuclide binds to a moveable particle it may be repeatedly suspended, transported, and re-deposited. Whether the nuclide binds to a moveable or immovable particle determines the type of biota it encounters. Therefore, it is of great value to understand how bottom types are spread in the sea close to a proposed repository and how the distribution of these bottoms have changed over time, in order to predict what may happen if a nuclide leaks from a repository. In the coastal areas of Forsmark and Laxemar, the sediment dynamics have been modelled for the period between 9500 BC and 9500 AD. The model is based on a wave model (STWAVE) included in the program package from SMS (Surface Water Modelling System). A sediment resuspension module was developed and is presented in this report. The model inputs are weather data (wind direction and wind speed) and bathymetry. The bathymetry is in a regular grid structure. The wave model is separated into two steps. The first is an outer model with coarse resolution (1000 m) that represents the whole Baltic Sea. This outer model gives border conditions to an inner model with higher resolution (100 m) that represents the coastal areas close to Forsmark and Laxemar. The outputs from the wave model are wave height, wave period and water depth for each cell in the model domains. A new program module, written in VisualBasic, reads the results from the wave module and calculates the maximum wave generated water velocity close to the sea bottom, and the maximum resuspendable grain size at that water velocity based on a semi-empirical relationship. The model is run with a time step of 500 years. Since the bathymetry is changing over time due to the positive shore displacement, a sub-model for the Baltic Sea evolution has

  9. Composition of sediments in the coastal zones of Costa Rica using fluorescence of ray-X (FRX)

    International Nuclear Information System (INIS)

    Salazar Matarrita, Alfonso; Lizano Rodriguez, Omar G.; Alfaro, Eric J.

    2003-01-01

    Using an energy dispersive X-Ray fluorescence analysis, simultaneous evaluation of K, Ca, Ti, Cr, Mn, Ge, Ni, Cu, Zn, Br, Rb, Sr and Pb in 74 marine sediment samples from the Costa Rica intertidal zones was conducted. Samples were collected between June 1999 and December 2001, from Caribbean and Pacific beaches of Costa Rica. Calcium and iron showed the highest abundances and are indicators of the natural origin of the sediments. Calcium is associated with biogenic processes such as coral reefs near the sampling sites and iron indicates a terrigenous origin. In general, the beaches of the Caribbean and North Pacific regions showed the greatest concentration of calcium. This is indicative of the abundant reef structures near these beaches. The beaches of the Central and South Pacific show the greatest iron concentrations, indicating an important lithosphere contribution and/or little contribution of calcium carbonate due to the poor development of coralline structures near the sampling sites. Finally, the analyses did not show evidence of elements associated with anthropogenic pollution. Only a northern section of Puerto Viejo beach showed high concentrations of lead, zinc and titanium, perhaps associated with hydrothermal sources. (author)

  10. Process-based and Surrogate Modelling of Fine Sediment Transport in the Dutch Coastal Zone

    NARCIS (Netherlands)

    Kai, C.

    2009-01-01

    Coastal zones which are known as the interface between continents and oceans are vital and important to human beings because a majority of the world's population live in such zones (Nelson, 2007). Coastal systems are among the most dynamic and energetic environments on earth and they are

  11. Toward a community coastal sediment transport modeling system: the second workshop

    Science.gov (United States)

    Sherwood, Christopher R.; Harris, Courtney K.; Geyer, W. Rockwell; Butman, Bradford

    2002-01-01

    Models for transport and the long-term fate of particles in coastal waters are essential for a variety of applications related to commerce, defense, public health, and the quality of the marine environment. Examples include: analysis of waste disposal and transport and the fate of contaminated materials; evaluation of burial rates for naval mines or archaeological artifacts; prediction of water-column optical properties; analysis of transport and the fate of biological particles; prediction of coastal flooding and coastal erosion; evaluation of impacts of sea-level or wave-climate changes and coastal development; planning for construction and maintenance of navigable waterways; evaluation of habitat for commercial fisheries; evaluation of impacts of natural or anthropogenic changes in coastal conditions on recreational activities; and design of intakes and outfalls for sewage treatment, cooling systems, and desalination plants.

  12. Rapid sedimentation of iron oxyhydroxides in an active hydrothermal shallow semi-enclosed bay at Satsuma Iwo-Jima Island, Kagoshima, Japan

    Science.gov (United States)

    Kiyokawa, Shoichi; Ueshiba, Takuya

    2015-04-01

    Hydrothermal activity is common in the fishing port of Nagahama Bay, a small semi-enclosed bay located on the southwest coast of Satsuma Iwo-Jima Island (38 km south of Kyushu Island, Japan). The bay contains red-brown iron oxyhydroxides and thick deposits of sediment. In this work, the high concentration and sedimentation rates of oxyhydroxide in this bay were studied and the sedimentary history was reconstructed. Since dredging work in 1998, a thickness of 1.0-1.5 m of iron oxyhydroxide-rich sediments has accumulated on the floor of the bay. To estimate the volume of iron oxyhydroxide sediments and the amount discharged from hydrothermal vents, sediment traps were operated for several years and 13 sedimentary core samples were collected to reconstruct the 10-year sedimentary history of Nagahama Bay. To confirm the timing of sedimentary events, the core data were compared with meteorological records obtained on the island, and the ages of characteristic key beds were thus identified. The sedimentation rate of iron oxyhydroxide mud was calculated, after correcting for sediment input from other sources. The sediments in the 13 cores from Nagahama Bay consist mainly of iron oxyhydroxide mud, three thick tephra beds, and a topmost thick sandy mud bed. Heavy rainfall events in 2000, 2001, 2002, and 2004-2005 coincide with tephra beds, which were reworked from Iwo-Dake ash deposits to form tephra-rich sediment. Strong typhoon events with gigantic waves transported outer-ocean-floor sediments and supplied quartz, cristobalite, tridymite, and albite sands to Nagahama Bay. These materials were redeposited together with bay sediments as the sandy mud bed. Based on the results from the sediment traps and cores, it is estimated that the iron oxyhydroxide mud accumulated in the bay at the relatively rapid rate of 33.3 cm/year (from traps) and 2.8-4.9 cm/year (from cores). The pore water contents within the sediment trap and core sediments are 73%-82% and 47%-67%, respectively

  13. Towards predicting basin-wide invertebrate organic biomass and production in marine sediments from a coastal sea.

    Directory of Open Access Journals (Sweden)

    Brenda J Burd

    Full Text Available Detailed knowledge of environmental conditions is required to understand faunal production in coastal seas with topographic and hydrographic complexity. We test the hypothesis that organic biomass and production of subtidal sediment invertebrates throughout the Strait of Georgia, west coast of Canada, can be predicted by depth, substrate type and organic flux modified to reflect lability and age of material. A basin-wide database of biological, geochemical and flux data was analysed using an empirical production/biomass (P/B model to test this hypothesis. This analysis is unique in the spatial extent and detail of P/B and concurrent environmental measurements over a temperate coastal region. Modified organic flux was the most important predictor of organic biomass and production. Depth and substrate type were secondary modifiers. Between 69-74% of variability in biomass and production could be explained by the combined environmental factors. Organisms <1 mm were important contributors to biomass and production primarily in shallow, sandy sediments, where high P/B values were found despite low organic flux. Low biomass, production, and P/B values were found in the deep, northern basin and mainland fjords, which had silty sediments, low organic flux, low biomass of organisms <1 mm, and dominance by large, slow-growing macrofauna. In the highest organic flux and biomass areas near the Fraser River discharge, production did not increase beyond moderate flux levels. Although highly productive, this area had low P/B. Clearly, food input is insufficient to explain the complex patterns in faunal production revealed here. Additional environmental factors (depth, substrate type and unmeasured factors are important modifiers of these patterns. Potential reasons for the above patterns are explored, along with a discussion of unmeasured factors possibly responsible for unexplained (30% variance in biomass and production. We now have the tools for basin

  14. Biomagnification of some heavy and essential metals in sediments, fishes and crayfish from Ondo State coastal region, Nigeria

    International Nuclear Information System (INIS)

    Asaolu, S.S.; Olaofe, O.

    2005-01-01

    The bio magnifications levels of some essential (Fe, Zn, Cu) and toxic metals (Pb, Ni, Cd, Cr, Co, Mn) were determined in sediments, three kinds of fish (Oreochromis niloticus, Synodonthis sp., and Clarias gariepinus) and crayfish from the Ondo State coastal region. The metal bio magnification in the fish and crayfish was several times greater than in water, while that in the sediments was several thousand-folds greater than in both the organisms and water. Among the metals examined in water, Fe was the most abundant with average values of 146.7 and 74.3 mg/1, respectively, for wet and dry seasons, while Co was the least with average values of 2.4 and 1.6 mg/1. In the sediments, concentrations of Pb, Ni, Fe, Cr, Co and Mn in the wet season were relatively higher than those obtained for the dry season. Fe with an average of 50.9 mg/kg in C, gariepinus was the most abundant metal in the fish samples, while Cu with an average value of 0.3 mg/kg in O. niloticus was the least. The metal bio magnification for most of the metals for both seasons was found to vary widely from one location to the other. This was confirmed by the coefficient of variation that ranged from 31% to 144% and 29% to 130% in the wet and dry seasons, respectively. The present study has shown that fish, crayfish and sediments can be used to monitor the pollution level of metals in the Nigerian coastal water. (author)

  15. Seasonal variation of early diagenesis and greenhouse gas production in coastal sediments of Cadiz Bay: Influence of anthropogenic activities

    Science.gov (United States)

    Burgos, Macarena; Ortega, Teodora; Bohórquez, Julio; Corzo, Alfonso; Rabouille, Christophe; Forja, Jesús M.

    2018-01-01

    Greenhouse gas production in coastal sediments is closely associated with the early diagenesis processes of organic matter and nutrients. Discharges from anthropogenic activities, particularly agriculture, fish farming and waste-water treatment plants supply large amounts of organic matter and inorganic nutrients that affect mineralization processes. Three coastal systems of Cadiz Bay (SW Spain) (Guadalete River, Rio San Pedro Creek and Sancti Petri Channel) were chosen to determine the seasonal variation of organic matter mineralization. Two sampling stations were selected in each system; one in the outer part, close to the bay, and another more inland, close to a discharge point of effluent related to anthropogenic activities. Seasonal variation revealed that metabolic reactions were driven by the annual change of temperature in the outer station of the systems. In contrast, these reactions depended on the amount of organic matter reaching the sediments in the outermost part of the systems, which was higher during winter. Oxygen is consumed in the first 0.5 cm indicating that suboxic and anoxic processes, such as denitrification, sulfate reduction and methanogenesis are important in these sediments. Sulfate reduction seems to account for most of the mineralization of organic matter at the marine stations, while methanogenesis is the main pathway at the sole freshwater station of this study, located inside the estuary of the Guadalete River, because of the lack of sulfate as electron acceptor. Results point to denitrification being the principal process of N2O formation. Diffusive fluxes varied between 2.6 and 160 mmol m-2 d-1 for dissolved inorganic carbon (DIC); 0.9 and 164.3 mmol m-2 d-1 for TA; 0.8 and 17.4 μmol m-2 d-1 for N2O; and 0.1 μmol and 13.1 mmol m-2 d-1 for CH4, indicating that these sediments act as a source of greenhouse gases to the water column.

  16. Determination of distribution coefficient (Kd's) of some artificial and naturally occurring radionuclide in fresh and marine coastal water sediment

    International Nuclear Information System (INIS)

    Al-Masri, M. S.; Mamish, S; Haleem, M. A.

    2004-12-01

    Distribution coefficients of artificial and natural radionuclides in fresh and marine water sediment are used in modeling radionuclide dispersion in water system, and the radiation risk and environmental investigating of impact of radioactive emissions, due to routine operations of nuclear plants or disposal and burial of radioactive waste in the environment. In the present work, distribution coefficient of uranium, lead, polonium, radium (naturally occurring radionuclides that may be emitted into the Syrian environment by the phosphate and oil industry with relatively high concentrations) and caesium 137 and strontium 85, in fresh water sediment (Euphrates River, Orantos River and Mzzerib Lake) and marine coastal water (Lattakia, Tartous and Banias). Distribution coefficients were found to vary between (5.8-17.18)*10 3 , (2.2-8.11)*10 3 , (0.22-2.08)*10 3 , (0.16-0.19)*10 3 , (0.38-0.69)*10 3 and 49-312 for polonium, lead, uranium, radium, cesium and strontium respectively. Results have indicated that most measurement distribution coefficients in the present study were lower than those values reported in IAEA documents for marine coastal sediment. In addition, variations of Kd's with aqueous phase composition and sediment elemental and mineralogical composition and its total organic materials content have been studied, where liner correlation coefficients for each isotope with different parameters have been determined. The obtained data reported in this study can be used for radioactive contaminants dispersion and transfer in Syrian river, lake and coast to assess risks to public due to discharges of the phosphate and oil industry into the Syrian environment. (Authors)

  17. Statistical validation of the model of diffusion-convection (MDC) of 137Cs for the assessment of recent sedimentation rates in coastal systems

    International Nuclear Information System (INIS)

    Paulo Alves de Lima Ferreira; Eduardo Siegle; Michel Michaelovitch de Mahiques; Rubens Cesar Lopes Figueira; Carlos Augusto Franca Schettini

    2015-01-01

    This study aimed the validation of the model of diffusion-convection (MDC) of 137 Cs for the calculation of recent sedimentation rates in 13 sedimentary cores of two Brazilian coastal systems, the Cananeia-Iguape and Santos-Sao Vicente estuarine systems. The MDC covers key factors responsible for 137 Cs vertical migration in sediments: its diffusion to the interstitial water and the vertical convection of this water through the sediments. This study successfully validated the MDC use to determine sedimentation rates, which was statistically validated not only with 210 Pb xs (unsupported 210 Pb) models, widely used in oceanographic studies, but also by literature values for those regions. (author)

  18. The effects of wastewater effluent and river discharge on benthic heterotrophic production, organic biomass and respiration in marine coastal sediments

    International Nuclear Information System (INIS)

    Burd, B.; Macdonald, T.; Bertold, S.

    2013-01-01

    Highlights: • High river particulate flux results in low sediment P/B due to large burrowers. • Sewage deposition results in high P/B from biomass depletion and bacterial increase. • Heterotrophic production was 56% of oxidized OC flux with 35% growth efficiency. • Production was correlated with organic/inorganic flux – biomass was not. • δ 15 N patterns illustrate feeding strategies of key taxa near the outfall. -- Abstract: We examine effects of high river particulate flux and municipal wastewater effluent on heterotrophic organic carbon cycling in coastal subtidal sediments. Heterotrophic production was a predictable (r 2 = 0.95) proportion (56%) of oxidized OC flux and strongly correlated with organic/inorganic flux. Consistent growth efficiencies (36%) occurred at all stations. Organic biomass was correlated with total, OC and buried OC fluxes, but not oxidized OC flux. Near the river, production was modest and biomass high, resulting in low P/B. Outfall deposition resulted in depleted biomass and high bacterial production, resulting in the highest P/B. These patterns explain why this region is production “saturated”. The δ 15 N in outfall effluent, sediments and dominant taxa provided insight into where, and which types of organisms feed directly on fresh outfall particulates, on older, refractory material buried in sediments, or utilize chemosynthetic symbiotic bacteria. Results are discussed in the context of declining bottom oxygen conditions along the coast

  19. Organic matter composition in the sediment of three Brazilian coastal lagoons: district of Macaé, Rio de Janeiro (Brazil).

    Science.gov (United States)

    Zink, Klaus-Gerhard; Furtado, André L S; Casper, Peter; Schwark, Lorenz

    2004-03-01

    Freshwater lagoons comprise important coastal ecosystems and natural buffers between urbanized land areas and open ocean in the Rio de Janeiro State, Brazil. Studies of sediment and water chemistry, zooplankton and bacterial communities to assess the extent of anthropogenic disturbance are available. Here we contribute with an organic-geochemical approach supplemented by some microbiological aspects to complete the characterization of these lagoonal ecosystems. Bulk organic matter and extractable lipids (aliphatic hydrocarbons, alcohols and fatty acids, sterols) were investigated from two locations per lagoon: at the seaward site and landward ends - and at two depth intervals (0-3 and 3-6 cm) per site. Urbanized Imboacica Lagoon received increased anthropogenic input over the most recent years represented by the topmost 3 cm of sediment, whereas deeper sediment layers are less affected by human influence. Eutrophication or nutrient availability favored enhanced algal/cyanobacterial growth. In remote Cabiúnas and Comprida Lagoons pristine conditions are preserved. Organic matter from vascular plants dominates (chain length of free lipids up to C36), which is exceptionally well preserved by acidic lagoonal waters. Differentiation between landward and seaward sites in these two lagoons is less well established due to much smaller surface/volume to catchment ratios. No anthropogenic influences are yet detectable in sediments of Cabiúnas and Comprida Lagoons.

  20. Nitrogen removal through N cycling from sediments in a constructed coastal marsh as assessed by 15N-isotope dilution.

    Science.gov (United States)

    Ro, Hee-Myong; Kim, Pan-Gun; Park, Ji-Suk; Yun, Seok-In; Han, Junho

    2018-04-01

    Constructed coastal marsh regulates land-born nitrogen (N) loadings through salinity-dependent microbial N transformation processes. A hypothesis that salinity predominantly controls N removal in marsh was tested through incubation in a closed system with added- 15 NH 4 + using sediments collected from five sub-marshes in Shihwa marsh, Korea. Time-course patterns of concentrations and 15 N-atom% of soil-N pools were analyzed. Sediments having higher salinity and lower soil organic-C and acid-extractable organic-N exhibited slower rates of N mineralization and immobilization, nitrification, and denitrification. Rates of denitrification were not predicted well by sediment salinity but by its organic-C, indicating heterotrophic denitrification. Denitrification dominated N-loss from this marsh, and nitrogen removal capacity of this marsh was estimated at 337 kg N day -1 (9.9% of the daily N-loadings) considering the current rooting depth of common reeds (1.0 m). We showed that sediment N removal decreases with increasing salinity and can increase with increasing organic-C for heterotrophic denitrification. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Characteristics, distribution and sources of polychlorinated biphenyls (PCBs) in coastal sediments from the heavily industrialized area of Asalouyeh, Iran.

    Science.gov (United States)

    Arfaeinia, Hossein; Asadgol, Zahra; Ahmadi, Ehsan; Seifi, Morteza; Moradi, Masoud; Dobaradaran, Sina

    2017-12-01

    In this research, the levels of polychlorinated biphenyls (PCBs) were investigated in the marine sediments of Asaluyeh harbor, in the Persian Gulf. The samples were taken from industrial, semi-industrial and urban regions. The mean concentration levels of total (Σ) 18 detected PCBs were 514.32, 144.67 and 31.6 pg/g dw for the industrial, semi-industrial and urban sampling stations, respectively. Based on a multivariate statistical analysis, it was found that high contamination levels of PCBs in sediments collected along the Persian Gulf were associated with releases from local industries. Total organic carbon (TOC) content was significantly and positively correlated with the concentrations of PCB congeners. World Health Organization toxic equivalents (TEQs) for PCBs ranged from 0.04 to 2.66 pg TEQ/g dry weight (dw) in the coastal sediments. The TEQ values in this study were higher than many reported worldwide in the literature for sediments. This suggests that there are high levels of contamination in the area due to industrial and other human activities.

  2. Taxonomic profiling of bacterial community structure from coastal sediment of Alang-Sosiya shipbreaking yard near Bhavnagar, India.

    Science.gov (United States)

    Patel, Vilas; Munot, Hitendra; Shah, Varun; Shouche, Yogesh S; Madamwar, Datta

    2015-12-30

    The Alang-Sosiya shipbreaking yard (ASSBY) is considered the largest of its kind in the world, and a major source of anthropogenic pollutants. The aim of this study was to investigate the impact of shipbreaking activities on the bacterial community structure with a combination of culture-dependent and culture-independent approaches. In the culture-dependent approach, 200 bacterial cultures were isolated and analyzed by molecular fingerprinting and 16S ribosomal RNA (r-RNA) gene sequencing, as well as being studied for degradation of polycyclic aromatic hydrocarbons (PAHs). In the culture-independent approach, operational taxonomic units (OTUs) were related to eight major phyla, of which Betaproteobacteria (especially Acidovorax) was predominantly found in the polluted sediments of ASSBY and Gammaproteobacteria in the pristine sediment sample. The statistical approaches showed a significant difference in the bacterial community structure between the pristine and polluted sediments. To the best of our knowledge, this is the first study investigating the effect of shipbreaking activity on the bacterial community structure of the coastal sediment at ASSBY. Copyright © 2015. Published by Elsevier Ltd.

  3. Optimization of biostimulant for bioremediation of contaminated coastal sediment by response surface methodology (RSM) and evaluation of microbial diversity by pyrosequencing.

    Science.gov (United States)

    Subha, Bakthavachallam; Song, Young Chae; Woo, Jung Hui

    2015-09-15

    The present study aims to optimize the slow release biostimulant ball (BSB) for bioremediation of contaminated coastal sediment using response surface methodology (RSM). Different bacterial communities were evaluated using a pyrosequencing-based approach in contaminated coastal sediments. The effects of BSB size (1-5cm), distance (1-10cm) and time (1-4months) on changes in chemical oxygen demand (COD) and volatile solid (VS) reduction were determined. Maximum reductions of COD and VS, 89.7% and 78.8%, respectively, were observed at a 3cm ball size, 5.5cm distance and 4months; these values are the optimum conditions for effective treatment of contaminated coastal sediment. Most of the variance in COD and VS (0.9291 and 0.9369, respectively) was explained in our chosen models. BSB is a promising method for COD and VS reduction and enhancement of SRB diversity. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Geochemistry of organic carbon and nitrogen in surface sediments of coastal Bohai Bay inferred from their ratios and stable isotopic signatures

    International Nuclear Information System (INIS)

    Gao Xuelu; Yang Yuwei; Wang Chuanyuan

    2012-01-01

    Total organic carbon (TOC), total nitrogen (TN) and their δ 13 C and δ 15 N values were determined for 42 surface sediments from coastal Bohai Bay in order to determine the concentration and identify the source of organic matter. The sampling sites covered both the marine region of coastal Bohai Bay and the major rivers it connects with. More abundant TOC and TN in sediments from rivers than from the marine region reflect the situation that most of the terrestrial organic matter is deposited before it meets the sea. The spatial variation in δ 13 C and δ 15 N signatures implies that the input of organic matter from anthropogenic activities has a more significant influence on its distribution than that from natural processes. Taking the area as a whole, surface sediments in the marine region of coastal Bohai Bay are dominated by marine derived organic carbon, which on average accounts for 62 ± 11% of TOC.

  5. Iron bacterial phylogeny and their execution towards iron availability in Equatorial Indian Ocean and Coastal Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Rajasabapathy, R.; Mohandass, C.; VijayRaj, A.S.; Madival, V.V.; Meena, R.M.

    -264. Edwards K.J., W. Bach, T.M. McCollom and D.R. Rogers. 2004. Neutrophilic Iron-Oxidizing Bacteria in the Ocean: Their Habitats, Diversity, and Roles in Mineral Deposition, Rock Alteration, and Biomass Production in the Deep-Sea. Geomicrobiol. J. 21: 393...-404. Edwards K.J., D.R. Rogers, C.O. Wirsen and T.M. McCollom. 2003. Isolation and characterization of novel psychrophilic, neutrophilic, Fe-oxidizing chemolitho-autotrophic α- and γ -Proteobacteria from the deep sea. Appl. Environ. Microbiol. 69: 2906...

  6. Temporal fluctuations in grain size, organic materials and iron concentrations in intertidal surface sediment of San Francisco Bay

    Science.gov (United States)

    Thomson-Becker, E. A.; Luoma, S.N.

    1985-01-01

    The physical and chemical characteristics of the oxidized surface sediment in an estuary fluctuate temporally in response to physical forces and apparently-fluctuating inputs. These characteristics, which include grain size and concentrations of organic materials and iron, will influence both trace-metal geochemistry and bioavailability. Temporal trends in the abundance of fine particles, total organic carbon content (TOC), absorbance of extractable organic material (EOM), and concentration of extractable iron in the sediment of San Francisco Bay were assessed using data sets containing approximately monthly samples for periods of two to seven years. Changes in wind velocity and runoff result in monthly changes in the abundance of fine particles in the intertidal zone. Fine-grained particles are most abundant in the late fall/early winter when runoff is elevated and wind velocities are low; particles are coarser in the summer when runoff is low and wind velocities are consistently high. Throughout the bay, TOC is linearly related to fine particle abundance (r = 0.61). Temporal variability occurs in this relationship, as particles are poor in TOC relative to percent of fine particles in the early rainy season. Iron-poor particles also appear to enter the estuary during high runoff periods; while iron is enriched on particle surfaces in the summer. Concentrations of extractable iron and absorbance of EOM vary strongly from year to year. Highest absorbances of EOM occurred in the first year following the drought in 1976-77, and in 1982 and 1983 when river discharge was unusually high. Extractable-iron concentrations were also highest in 1976-77, but were very low in 1982 and 1983. ?? 1985 Dr W. Junk Publishers.

  7. 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

    Science.gov (United States)

    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.

  8. Can sediments at hydrocarbon seep sites represent a source for marine bioavailable iron? — A case study from the South China Sea

    Science.gov (United States)

    Li, N.; Feng, D.; Chen, D.

    2017-12-01

    Niu Li1, Dong Feng1,2, and Duofu Chen2,31CAS Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China. 2Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China. 3Hadal Science and Technology Research Center, College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, China. Iron is an essential micronutrient and commonly considered to be one of the key-limiting factors for biological productivity in many ocean regions. Seafloor Fe supply should be most efficient in suboxic conditions. Recent studies shown that widely spread anoxic environments can develop in hydrocarbon seep sediment and local bottom water, owing to the occurrence of aerobic and/or anaerobic methane oxidation. Under this condition, the iron in sediment can be reduced to dissolved Fe2+ in the ocean. However, questions remain about whether the hydrocarbon seep sediment can represent a source for bioavailable iron to the ocean, and the control factor for the transformation of iron in the sediment remains largely unexplored. For a number of hydrocarbon seeps from the northern and southern South China Sea, the iron speciation, pyrite sulfur isotope, and iron isotope, as well as the major and trace elements are used to constrain the intensity of cold seep, and its impact on transformation of iron in sediment. Samples from both areas show sediment iron lost during the high methane flux conditions, owing to the suboxic conditions cause by aerobic methane oxidation. On the other hand, high sediment iron content accompanied by high sulfur content can be seen during the conditions of high methane flux without the occurrence of aerobic methane oxidation, which is possible ascribed to the anaerobic methane oxidation and the release of iron through seep activity. This study reveals the transformation of iron in the sediment is closely related to the

  9. 226Ra-210Pb-210Po Levels in Marine Biota and Surface Coastal Sediments from the Red Sea, Sudan

    International Nuclear Information System (INIS)

    Sirelkhatim, D.A.; Sam, A.K.; Hassona, R.K.

    2003-01-01

    This paper presents data on 226 Ra, 210 Pb and 210 Po activity concentration levels in multicellular marine algae, molluscs, coral as well as in surface marine sediments collected from the shallower waters of the fringing reefs area extending towards north and south (Flamingo bay) of Port sudan harbour. The analyses were performed adopting a simple time efficient method combining alpha-spectrometry, liquid scintillation and Cerenkov counting technique. Generally speaking, surface sediments from this coastal region are poor in their radioactivity content in contrast to similar data reported from different coastal areas around the globe. There is surface enrichment of 210 Pb and 210 Po with respect to their progenitor 226 Ra as it is evident from the activity ratios of 210 Pb/ 226 Ra (3.03±1.79) and 210 Po/ 226 Ra (2.23±1.56). Among marine plants and animals investigated, the green algae species, Halimeda, and coral species, Favites, show substantial concentration of radium at 8.2 Bq/KXg and 21.9 Bq/KXg dry weight, respectively

  10. Exploring the Impacts of Anthropogenic Disturbance on Seawater and Sediment Microbial Communities in Korean Coastal Waters Using Metagenomics Analysis

    Directory of Open Access Journals (Sweden)

    Nam-Il Won

    2017-01-01

    Full Text Available The coastal ecosystems are considered as one of the most dynamic and vulnerable environments under various anthropogenic developments and the effects of climate change. Variations in the composition and diversity of microbial communities may be a good indicator for determining whether the marine ecosystems are affected by complex forcing stressors. DNA sequence-based metagenomics has recently emerged as a promising tool for analyzing the structure and diversity of microbial communities based on environmental DNA (eDNA. However, few studies have so far been performed using this approach to assess the impacts of human activities on the microbial communities in marine systems. In this study, using metagenomic DNA sequencing (16S ribosomal RNA gene, we analyzed and compared seawater and sediment communities between sand mining and control (natural sites in southern coastal waters of Korea to assess whether anthropogenic activities have significantly affected the microbial communities. The sand mining sites harbored considerably lower levels of microbial diversities in the surface seawater community during spring compared with control sites. Moreover, the sand mining areas had distinct microbial taxonomic group compositions, particularly during spring season. The microbial groups detected solely in the sediment load/dredging areas (e.g., Marinobacter, Alcanivorax, Novosphingobium are known to be involved in degradation of toxic chemicals such as hydrocarbon, oil, and aromatic compounds, and they also contain potential pathogens. This study highlights the versatility of metagenomics in monitoring and diagnosing the impacts of human disturbance on the environmental health of marine ecosystems from eDNA.

  11. TBT and its metabolites in sediments: Survey at a German coastal site and the central Baltic Sea.

    Science.gov (United States)

    Abraham, Marion; Westphal, Lina; Hand, Ines; Lerz, Astrid; Jeschek, Jenny; Bunke, Dennis; Leipe, Thomas; Schulz-Bull, Detlef

    2017-08-15

    Since the 1950s the organotin compound tributyltin (TBT) was intensively used in antifouling paints for marine vessels and it became of concern for the marine environment. Herein, we report on a study from 2015 on TBT and its metabolites monobutyltin (MBT) and dibutyltin (DBT) in sediments from the central Baltic Sea and a Baltic Sea coastal site with strong harbor activities (Warnemünde). Sublayers from a sediment core from the Arkona Basin were analyzed to investigate the long term organotin pressure for the Baltic Sea. For the central Baltic Sea total organotin (MBT+DBT+TBT) ranged from 100 to 500ng/g TOC with distinct areas of high organotin content probably due to historical inputs. For the coastal site total organotin ranged from 10,000 to 60,000ng/g TOC. MBT and DBT were the predominant organotin species detected. Overall, the data obtained indicate the progress of TBT degradation at the investigated sites. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Occurrence of halogenated flame retardants in sediment off an urbanized coastal zone: association with urbanization and industrialization.

    Science.gov (United States)

    Liu, Hui-Hui; Hu, Yuan-Jie; Luo, Pei; Bao, Lian-Jun; Qiu, Jian-Wen; Leung, Kenneth M Y; Zeng, Eddy Y

    2014-01-01

    To examine the impacts of urbanization and industrialization on the coastal environment, sediment samples were collected from an urbanized coastal zone (i.e., Daya Bay and Hong Kong waters of South China) and analyzed for 20 polybrominated diphenyl ethers (PBDEs) and 10 alternative halogenated flame retardants (AHFRs). The sum concentration of PBDEs was in the range of 1.7-55 (mean: 17) ng g(-1), suggesting a moderate pollution level compared to the global range. The higher fractions of AHFRs (i.e., TBB+TBPH, BTBPE and DBDPE) than those of legacy PBDEs (i.e., penta-BDE, octa-BDE and deca-BDE) corresponded with the phasing out of PBDEs and increasing demand for AHFRs. Heavy contamination occurred at the estuary of Dan'ao River flowing through the Daya Bay Economic Zone, home to a variety of petrochemicals and electronics manufacturing facilities. The concentrations of HFRs in surface sediments of Hong Kong were the highest in Victoria Harbor, which receives around 1.4 million tons of primarily treated sewage daily, and a good relationship (r(2) = 0.80; p 0.73; p < 0.05) with the production volume of electronic devices, production value of electronic industries and population size, demonstrating the importance of industrializing and urbanizing processes in dictating the historical input patterns of AHFRs.

  13. Distribution and metal contamination in the coastal sediments of Dammam Al-Jubail area, Arabian Gulf, Saudi Arabia.

    Science.gov (United States)

    El-Sorogy, Abdelbaset; Al-Kahtany, Khaled; Youssef, Mohamed; Al-Kahtany, Fahd; Al-Malky, Mazen

    2018-03-01

    Present work aims to document the distribution and metal contamination in the coastal sediments of the Dammam Al-Jubail area, Saudi Arabian Gulf. Twenty-six samples were collected for Al, V, Cr, Mn, Cu, Zn, Cd, Pb, Hg, Sr, As, Fe, Co and Ni analysis. Results of enrichment factor indicated that Sr, Cd, Cu, Hg, V, As, Ni, Cr and Zn gave enrichment factors higher than 2 (98.87, 40.28, 33.20, 27.87, 26.11, 14.10, 6.15, 3.72 and 2.62 respectively) implying anthropogenic sources, while Pb, Mn and Al have very low background level (1.37, 0.71, 0.124 respectively), probably originated from natural sources. Average concentrations of Sr, V, Hg, Cd and As were mostly higher than those from the background shale and the earth crust, the Caspian Sea, the Mediterranean Sea, the sediment quality guidelines, the Red Sea, the Gulf of Aqaba and the Gulf of Oman. The higher levels of the studied metals are mostly related samples with high Al and TOM content, as well as the visible anthropogenic pollutants along the studied coastline. The most recorded anthropogenic pollutants were sewage effluent, landfilling due to coastal infrastructure development, oil spills, petrochemical industries and desalination plants in Al-Jubail industrial city. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Sediment bacterial community structures and their predicted functions implied the impacts from natural processes and anthropogenic activities in coastal area.

    Science.gov (United States)

    Su, Zhiguo; Dai, Tianjiao; Tang, Yushi; Tao, Yile; Huang, Bei; Mu, Qinglin; Wen, Donghui

    2018-06-01

    Coastal ecosystem structures and functions are changing under natural and anthropogenic influences. In this study, surface sediment samples were collected from disturbed zone (DZ), near estuary zone (NEZ), and far estuary zone (FEZ) of Hangzhou Bay, one of the most seriously polluted bays in China. The bacterial community structures and predicted functions varied significantly in different zones. Firmicutes were found most abundantly in DZ, highlighting the impacts of anthropogenic activities. Sediment total phosphorus was most influential on the bacterial community structures. Predicted by PICRUSt analysis, DZ significantly exceeded FEZ and NEZ in the subcategory of Xenobiotics Biodegradation and Metabolism; and DZ enriched all the nitrate reduction related genes, except nrfA gene. Seawater salinity and inorganic nitrogen, respectively as the representative natural and anthropogenic factor, performed exact-oppositely in nitrogen metabolism functions. The changes of bacterial community compositions and predicted functions provide a new insight into human-induced pollution impacts on coastal ecosystem. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Coastal surface sediment quality assessment in Leizhou Peninsula (South China Sea) based on SEM-AVS analysis.

    Science.gov (United States)

    Li, Feng; Lin, Jin-qin; Liang, Yan-yan; Gan, Hua-yang; Zeng, Xiang-yun; Duan, Zhi-peng; Liang, Kai; Liu, Xing; Huo, Zhen-hai; Wu, Chang-hua

    2014-07-15

    Surface sediments from the coastal area of the Leizhou Peninsula in the South China Sea were collected and analyzed and the potential ecological risks in the area were assessed based on acid-volatile sulfide (AVS) model. The AVS levels are between 0.109 and 55.6 μmol g(-1), with the average at 4.45 μmol g(-1). The high AVS-concentration zones include the aquaculture areas of Liusha Bay and the densely populated areas of Zhanjiang Bay. The simultaneously extracted metals (SEM) range from 0.026 μmol g(-1) to 8.61 μmol g(-1), with the average at 0.843 μmol g(-1). Most of high SEM-concentration stations were located in ports or aquaculture zones. Most of the coastal surface sediments of the Leizhou Peninsula (90%) had no adverse biological effects according to the criterion proposed by USEPA (2005); while adverse effects were uncertain in some stations (8%); even in 2 stations (2%) adverse biological effects may be expected. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

    Digital Repository Service at National Institute of Oceanography (India)

    Manohar, C.S.; Raghukumar, C.

    and 5 applying the formula 3.14* r 2 * h, the total hyphal lengths were expressed as biovolume g -1 dry sediment. The biovolume was converted to biomass using the conversion factor 0.2 g cm -3 (Newell et al. 1986). The C biomass was calculated... in the sediment sections at St-I (A) & St-II (B). Bacterial C data during Oct 2005 and April 2006 is depicted as numbers*10 4 pg C g -1 dry sediments whereas it is numbers * 10 3 pg C g-1 dry sediment during the other sampling periods. Fungal C biomass...

  17. Eco-morphological Real-time Forecasting tool to predict hydrodynamic, sediment and nutrient dynamic in Coastal Louisiana

    Science.gov (United States)

    Messina, F.; Meselhe, E. A.; Buckman, L.; Twight, D.

    2017-12-01

    Louisiana coastal zone is one of the most productive and dynamic eco-geomorphic systems in the world. This unique natural environment has been alternated by human activities and natural processes such as sea level rise, subsidence, dredging of canals for oil and gas production, the Mississippi River levees which don't allow the natural river sediment. As a result of these alterations land loss, erosion and flood risk are becoming real issues for Louisiana. Costal authorities have been studying the benefits and effects of several restoration projects, e.g. freshwater and sediment diversions. The protection of communities, wildlife and of the unique environments is a high priority in this region. The Water Institute of the Gulf, together with Deltares, has developed a forecasting and information system for a pilot location in Coastal Louisiana, specifically for Barataria Bay and Breton Sound Basins in the Mississippi River Deltaic Plain. The system provides a 7-day forecast of water level, salinity, and temperature, under atmospheric and coastal forecasted conditions, such as freshwater riverine inflow, rainfall, evaporation, wind, and tide. The system also forecasts nutrient distribution (e.g., Chla and dissolved oxygen) and sediment transport. The Flood Early Warning System FEWS is used as a platform to import multivariate data from several sources, use them to monitor the pilot location and to provide boundary conditions to the model. A hindcast model is applied to compare the model results to the observed data, and to provide the initial condition to the forecast model. This system represents a unique tool which provides valuable information regarding the overall conditions of the basins. It offers the opportunity to adaptively manage existing and planned diversions to meet certain salinity and water level targets or thresholds while maximizing land-building goals. Moreover, water quality predictions provide valuable information on the current ecological

  18. Iron Oxide Minerals in Atmospheric Dust and Source Sediments-Studies of Types and Properties to Assess Environmental Effects

    Science.gov (United States)

    Reynolds, R. L.; Goldstein, H. L.; Moskowitz, B. M.; Till, J. L.; Flagg, C.; Kokaly, R. F.; Munson, S.; Landry, C.; Lawrence, C. R.; Hiza, M. M.; D'Odorico, P.; Painter, T. H.

    2011-12-01

    Ferric oxide minerals in atmospheric dust can influence atmospheric temperatures, accelerate melting of snow and ice, stimulate marine phytoplankton productivity, and impact human health. Such effects vary depending on iron mineral type, size, surface area, and solubility. Generally, the presence of ferric oxides in dust is seen in the red, orange, or yellow hues of plumes that originate in North Africa, central and southwest Asia, South America, western North America, and Australia. Despite their global importance, these minerals in source sediments, atmospheric dust, and downwind aeolian deposits remain poorly described with respect to specific mineralogy, particle size and surface area, or presence in far-traveled aerosol compounds. The types and properties of iron minerals in atmospheric dust can be better understood using techniques of rock magnetism (measurements at 5-300 K), Mössbauer and high-resolution visible and near-infrared reflectance spectroscopy; chemical reactivity of iron oxide phases; and electron microscopy for observing directly the ferric oxide coatings and particles. These studies can elucidate the diverse environmental effects of iron oxides in dust and can help to identify dust-source areas. Dust-source sediments from the North American Great Basin and Colorado Plateau deserts and the Kalahari Desert, southern Africa, were used to compare average reflectance values with a magnetic parameter (hard isothermal remanent magnetization, HIRM) for ferric oxide abundance. Lower reflectance values correspond strongly with higher HIRM values, indicating that ferric oxides (hematite or goethite, or both) contribute to absorption of solar radiation in these sediments. Dust deposited to snow cover of the San Juan Mountains (Colorado) and Wasatch Mountains (Utah) was used to characterize dust composition compared with properties of sediments exposed in source-areas identified from satellite retrievals. Results from multiple methods indicate that

  19. Environmental monitoring and assessment of antibacterial metabolite producing actinobacteria screened from marine sediments in south coastal regions of Karnataka, India.

    Science.gov (United States)

    Skariyachan, Sinosh; Garka, Shruthi; Puttaswamy, Sushmitha; Shanbhogue, Shobitha; Devaraju, Raksha; Narayanappa, Rajeswari

    2017-06-01

    Assessment of the therapeutic potential of secondary metabolite producing microorganisms from the marine coastal areas imparts scope and application in the field of environmental monitoring. The present study aims to screen metabolites with antibacterial potential from actionbacteria associated with marine sediments collected from south coastal regions of Karnataka, India. The actinobacteria were isolated and characterized from marine sediments by standard protocol. The metabolites were extracted, and antibacterial potential was analyzed against eight hospital associated bacteria. The selected metabolites were partially characterized by proximate analysis, SDS-PAGE, and FTIR-spectroscopy. The antibiogram of the test clinical isolates revealed that they were emerged as multidrug-resistant strains (P ≤ 0.05). Among six actinobacteria (IS1-1S6) screened, 100 μl -1 metabolite from IS1 showed significant antibacterial activities against all the clinical isolates except Pseudomonas aeruginosa. IS2 demonstrated antimicrobial potential towards Proteus mirabilis, Streptococcus pyogenes, and Escherichia coli. The metabolite from IS3 showed activity against Strep. pyogenes and E. coli. The metabolites from IS4, IS5, and IS6 exhibited antimicrobial activities against Ps. aeruginosa (P ≤ 0.05). The two metabolites that depicted highest antibacterial activities against the test strains were suggested to be antimicrobial peptides with low molecular weight. These isolates were characterized and designated as Streptomyces sp. strain mangaluru01 and Streptomyces sp. mangaloreK01 by 16S ribosomal DNA (rDNA) sequencing. This study suggests that south coastal regions of Karnataka, India, are one of the richest sources of antibacterial metabolites producing actinobacteria and monitoring of these regions for therapeutic intervention plays profound role in healthcare management.

  20. The impact of electrogenic sulfide oxidation on elemental cycling and solute fluxes in coastal sediment

    NARCIS (Netherlands)

    Rao, A.M.F.; Malkin, S.Y.; Hidalgo-Martinez, S.; Meysman, Filip

    2016-01-01

    Filamentous sulfide oxidizing cable bacteria are capable of linking the oxidation of free sulfide in deep anoxic layers of marine sediments to the reduction of oxygen or nitrate in surface sediments by conducting electrons over centimeter-scale distances. Previous studies have shown that this newly

  1. Declining sediment loads from Redwood Creek and the Klamath River, north coastal California

    Science.gov (United States)

    Randy D. Klein; Jeffrey K. Anderson

    2012-01-01

    River basin sediment loads are affected by several factors, with flood magnitude and watershed erosional stability playing dominant and dynamic roles. Long-term average sediment loads for northern California river basins have been computed by several researchers by several methods. However, characterizing the dynamic nature of climate and watershed stability requires...

  2. Suspended sediment behavior in a coastal dry-summer subtropical catchment: Effects of hydrologic preconditions

    Science.gov (United States)

    Variation in fluvial suspended sediment–discharge behavior is generally thought to be the product of changes in processes governing the delivery of sediment and water to the channel. The objective of this study was to infer sediment supply dynamics from the response of suspended ...

  3. Heavy metal pollutants in surficial sediments from different coastal sites in Aden Governorate, Yemen

    International Nuclear Information System (INIS)

    Ali, Anis Ahmed; Baharoon Aqil Abdulrahman

    2004-01-01

    Concentrations of Gd, Pb, Zn, Cu, Ni, Co, Cr, Mn and Fe in surficial sediments (<63μm) from the shores in Aden Governorate were determined by atomic absorption spectrophotometry method. The obtained concentration data show significant regional variations concerning both the total and leachable metals in sediments. Total metal concentrations of Cd and Pb were greatest in sediments from labor Island; Cu, Cr, and Fe occurred in the highest levels in Bandar Fuqum sediments, while maximum levels of Mn, Co, and Ni were observed in sediments from Sahel Abyan and Fuqum. Labile, easily extractable species of metals such as Cd and Pb, are similar to their total concentrations, and additionally Cu, Zn, Cr, and Fe were found in the highest concentrations in sediments from labor Island. Sediments from Sahel Abyan and Khawr Bir Ahmed were characterized by a maximum accumulation of bioavailable species of Co and Mn, respectively. The linear regression slopes for metals correlated were <1, this explains the slow enrichment of these metals in the sediments, and attributes their geological nature. (author)

  4. The Tsitsikamma coastal shelf, Agulhas Bank, South Africa: example of an isolated Holocene sediment trap

    Science.gov (United States)

    Flemming, Burg W.; Keith Martin, A.

    2018-02-01

    Under certain geomorphological conditions, sandy sediments supplied to a coast may become trapped in nearshore sedimentary compartments because these are laterally confined by bedload boundaries or convergences. Where sediment supply is small or the shoreface very steep, and accommodation space as a consequence large, the trapping mechanism may be very efficient. The Tsitsikamma coast along the South African south coast is a case in point, the sediment supplied by local rivers over the past 12 ka having been trapped in a nearshore sediment wedge extending at least 5 km offshore. On the basis of high-resolution seismic surveys, the volume of the sediment wedge has been estimated at 1,354×106 m3. As 5% of this volume is considered to have been contributed by bioclastic material of marine origin, the terrestrial input would be 1,286×106 m3. This amounts to an average annual terrestrial sediment input of 0.1072×106 m3. Using a detailed sediment yield map, the modern mean annual sediment supply to the Tsitsikamma coast by local rivers has been estimated at 0.1028×106 m3. Unless coincidental, the remarkable similarity of the two values suggests that the current climatic conditions along the Tsitsikamma coast correspond to the Holocene mean. This conclusion is supported by the currently available climate data for the South African south coast.

  5. Sediment type affects competition between a native and an exotic species in coastal China.

    Science.gov (United States)

    Li, Hong-Li; Wang, Yong-Yang; An, Shu-Qing; Zhi, Ying-Biao; Lei, Guang-Chun; Zhang, Ming-Xiang

    2014-10-23

    Different types of sediments in salt marsh have different physical and chemical characters. Thus sediment type plays a role in plant competition and growth in salt marsh ecosystems. Spartina anglica populations have been increasingly confined to upper elevation gradients of clay, and the niche sediment has changed. Because the niches of S. anglica and the native species Scirpus triqueter overlap, we conducted a greenhouse experiment to test the hypothesis that plant competition has changed under different types of sediments. Biomass and asexual reproduction were analyzed, and inter- and intraspecific competition was measured by log response ratio for the two species in both monoculture and combination under three sediment types (sand, clay and mixture of sand and clay). For S. anglica, biomass, ramet number and rhizome length in combination declined significantly compared with those in monoculture, and the intensity of interspecific competition was significantly higher than that of intraspecific competition under all sediments. For S. triqueter, the intensities of intra- and interspecific competition were not significantly different. This indicates that S. triqueter exerts an asymmetric competitive advantage over S. anglica across all sediments, but especially clay. Thus the sediment type changes competition between S. anglica and S. triqueter.

  6. A Risk-Based Characterization of Sediment Contamination by Legacy and Emergent Contaminants of Concern in Coastal British Columbia, Canada.

    Science.gov (United States)

    Morales-Caselles, Carmen; Desforges, Jean-Pierre W; Dangerfield, Neil; Ross, Peter S

    2017-08-01

    Sediments have long been used to help describe pollution sources, contaminated sites, trends over time, and habitat quality for marine life. We collected surficial sediments from 12 sites at an average seawater depth of 25 m in three near-urban areas of the Salish Sea (British Columbia, Canada) to investigate habitat quality for marine life, including heavily contaminated killer whales. Samples were analyzed using high-resolution instrumentation for a wide variety of congeners of polychlorinated biphenyls (PCBs), polybrominated diphenylethers (PBDEs), hexabromocyclododecane (HBCDD), polybrominated biphenyls, polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans, organochlorine pesticides, and polychlorinated naphthalenes (PCNs). The top six contaminant classes detected in sediments were ∑PCB > ∑PBDE > ∑PCDD/F > DDT > ∑HBCDD > ∑PCN. Near-urban harbor sediments had up to three orders of magnitude higher concentrations of contaminants than more remote sites. With limited tools available to characterize biological risks associated with complex mixtures in the real world, we applied several available approaches to prioritize the pollutant found in our study: (1) sediment quality guidelines from the Canadian Council of Ministers of the Environment where available; (2) US NOAA effects range low and other international guidelines; (3) total TEQ for dioxin-like PCBs for the protection of mammals; and (4) the calculation of risk quotients. Our findings provide an indication of the state of contamination of coastal environments in British Columbia and guidance for chemical regulations and priority setting, as well as management actions including best-practices, dredging, disposal at sea, and source control. In this regard, the legacy PCB and the emergent PBDEs should command continued priority monitoring.

  7. An integrated assessment of pollution and biological effects in flounder, mussels and sediment in the southern Baltic Sea coastal area.

    Science.gov (United States)

    Dabrowska, Henryka; Kopko, Orest; Lehtonen, Kari K; Lang, Thomas; Waszak, Ilona; Balode, Maija; Strode, Evita

    2017-02-01

    Organic and metal contaminants and biological effects were investigated in flounder, mussels, and sediments in the southern Baltic Sea coastal area in order to assess environmental quality status in that area. Four sites were selected, including two within the Gulf of Gdańsk (GoG). In biota and sediment at each site, DDTs dominated over PCBs and PBDEs were the least abundant among organic contaminants. Their concentrations decreased progressively outward from GoG. Among metal contaminants, the levels of Hg, Pb, and Cd were elevated in GoG. Biomarkers in flounder, EROD activity and DNA SB, showed moderate positive correlations with organic and metal contaminants. In flounder, the integrated biomarker index (IBR/n) presented a spatial trend coherent with chemical pollution index (CPI), but there was no clear spatial correspondence between IBR/n and CPI in mussels nor between sediment toxicity index (STI) and sediment CPI. The integrated assessment of contaminant and biological effect data against available assessment criteria indicated that in biota, the contaminant assessment thresholds were most often exceeded by CB-118, heptachlor, PBDE, and Hg (in the GoG sediments by p,p'-DDT, Hg and Cd), while of the biological determinants, the threshold was breeched by AChE activity in mussels in GoG. Applying the ICES/OSPAR traffic-light approach showed that of the 50 parameters assessed at each site, there were 18% of determinants in the red color category in the two GoG sites and 8% of determinants in the two sites outside GoG, which indicated that none of the four investigated sites attained good environmental status (GES).

  8. Sediment quality assessment in a coastal lagoon (Ravenna, NE Italy) based on SEM-AVS and sequential extraction procedure.

    Science.gov (United States)

    Pignotti, Emanuela; Guerra, Roberta; Covelli, Stefano; Fabbri, Elena; Dinelli, Enrico

    2018-09-01

    Sediments from the Pialassa Piomboni coastal lagoon (NE Italy) were studied to assess the degree of contamination and ecological risk related to trace metals by combining a geochemical characterization of bulk sediments with the assessment of the bioavailable forms of trace metals. With this purpose, sediment contamination (Cd, Cu, Hg, Ni, Pb, and Zn) was assessed by Enrichment Factors (EFs), and potential bioavailability by the Simultaneously Extracted Metals and Acid Volatile Sulfides (SEM-AVS) approach (Cd, Cu, Ni, Pb, and Zn), and by Sequential Extraction Procedure (Co, Cr, Cu, Ni, Pb, and Zn). On average, Cr and Ni exhibited no contamination (EF ≤1.5), and a predominance in the residual fraction of the sediment, indicating natural origin for these metals. Cu, Pb and Zn displayed a local contamination, which resulted in a higher proportion of Cu bound to the reducible and oxidizable fractions (~30% and ~40% as median, respectively), and Pb mostly associated with the reducible phase (~60% as median). Hence, Cu and Pb could be mobilized when environmental conditions become reducing or oxidizing. Zn resulted mainly partitioned into the reducible and residual fractions (~50% as median, in both fractions). The Risk Assessment Code (RAC) indicated that approximately 30% of samples had >10% of total Zn weakly bound to the sediment, suggesting a medium risk of exposure for aquatic organisms. RAC results were consistent with the ∑SEM-AVS findings, pointing to possible adverse effects for aquatic biota in ~30% of samples, with Zn mostly accounting for the total metal bioavailability. Hg showed a moderate to very severe enrichment, indicating that a substantial amount of this metal derives from anthropogenic sources and may pose adverse effects on the aquatic biota of the Pialassa Piomboni lagoon. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Arsenic enrichment in estuarine sediments-impact of iron and manganese mining

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, M.; Joseph, T.; Balachandran, K.K.; Nair, K.K.C.; Paimpillii, J.S.

    River Mandovi and Zuari, Goa (west coast of India) are flowing through iron and manganese mining areas and are heavily used for iron and manganese ore transport. This region generates 25-30 million tons of mining rejects per year. The iron ore...

  10. Spatial distribution and metal contamination in the coastal sediments of Al-Khafji area, Arabian Gulf, Saudi Arabia.

    Science.gov (United States)

    Alharbi, Talal; Alfaifi, Hussain; Almadani, Sattam A; El-Sorogy, Abdelbaset

    2017-11-13

    To document the spatial distribution and metal contamination in the coastal sediments of the Al-Khafji area in the northern part of the Saudi Arabian Gulf, 27 samples were collected for Al, V, Cr, Mn, Cu, Zn, Cd, Pb, Hg, Sr, As, Fe, Co, and Ni analysis using inductively coupled plasma-mass spectrometer (ICP-MS). The results revealed the following descending order of the metal concentrations: Sr > Fe > Al > As > Mn > Ni > V > Zn > Cr > Cu > Pb > Co > Hg > Cd. Average levels of enrichment factor of Sr, As, Hg, Cd, Ni, V, Cu, Co, and Pb were higher than 2 (218.10, 128.50, 80.94, 41.50, 12.31, 5.66, 2.95, 2.90, and 2.85, respectively) and that means the anthropogenic sources of these metals, while Al, Zn, Cr and Mn have enrichment factor less than 2, which implies natural sources. Average values of Sr, Hg, Cd, Cr, Ni, and As in the coastal sediments of Al-Khafji area were mostly higher than the values recorded from the background shale and earth crust and from those results along coasts of the Caspian Sea and the Mediterranean Sea. The highest levels of Cu in the northern part of the studied coastline might be due to Al-Khafji desalination plant, while levels of Al, Ni, Cr, Fe, Mn, Pb, and Zn in the central part may be a result of landfilling and industrial sewage. The highest levels of As, Cd, Co, Cu, Hg, and V in the southern part seem to be due to oil pollutants from Khafji Joint Operations (KJO). The higher values of Sr in the studied sediments in general and particularly in locality 7 could relate to the hypersalinity and aragonitic composition of the scleractinian corals abundant in that area.

  11. Occurrence of microplastics in the coastal marine environment: First observation on sediment of China

    International Nuclear Information System (INIS)

    Qiu, Qiongxuan; Peng, Jinping; Yu, Xubiao; Chen, Fangchaizi; Wang, Jundong; Dong, Fenqiang

    2015-01-01

    Highlights: • The quantity and composition of microplastics are investigated at 5 sediment sites in China for the first time. • The number of microplastics was at the range of 251–436 items/50 g sediment. • Polyesters, polyethylene terephthalate, high density polyesters and polystyrene were identified using u-FTIR. - Abstract: Microplastics in sediments from the Beibu Gulf and the coastline of China Sea were investigated to evaluate the occurrence and abundance of microplastics in China for the first time. Microplastics (<5 mm) were taken from sediments by a flotation method. The number of microplastics was counted by a fluorescence microscope, an instrument that is rarely used in the detection of microplastics in sediments. This instrument led to results that were satisfactory. Compared with other sampled areas, microplastics were found in massive concentrations in China. Four types of microplastics, HDPE, PET, PE and PS, were identified. The results will provide useful background information for further investigations

  12. Evaluating Environment, Erosion and Sedimentation Aspects in Coastal Area to Determine Priority Handling (A Case Study in Jepara Regency, northern Central Java, Indonesia)

    Science.gov (United States)

    Wahyudi, S. I.; Adi, H. P.

    2018-04-01

    Many areas of the northern coastal in Central Java, Indonesia, have been suffering from damage. One of the areas is Jepara, which has been experiencing this kind of damage for 7.6 kilometres from total 72 kilometres long beach. All damages are mostly caused by coastal erosion, sedimentation, environment and tidal flooding. Several efforts have been done, such as replanting mangroves, building revetment and groins, but it still could not mitigated the coastal damage. The purposes of this study are to map the coastal damages, to analyze handling priority and to determine coastal protection model. The method used are by identifying and plotting the coastal damage on the map, assessing score of each variable, and determining the handling priority and suitable coastal protection model. There are five levels of coastal damage used in this study, namely as light damage, medium, heavy, very heavy, and extremely heavy. Based on the priority assessment of coastal damage, it needs to be followed up by designing in detail and implementing through soft structure for example mangrove, sand nourishes and hard structure, such as breakwater, groins and revetment.

  13. Organic carbon sedimentation rates in Asian mangrove coastal ecosystems estimated by 210PB chronology

    International Nuclear Information System (INIS)

    Tateda, Y.; Wattayakorn, G.; Nhan, D.D.; Kasuya, Y.

    2004-01-01

    Organic carbon balance estimation of mangrove coastal ecosystem is important for understanding of Asian coastal carbon budget/flux calculation in global carbon cycle modelling which is powerful tool for the prediction of future greenhouse gas effect and evaluation of countermeasure preference. Especially, the organic carbon accumulation rate in mangrove ecosystem was reported to be important sink of carbon as well as that in boreal peat accumulation. For the estimation of 10 3 years scale organic carbon accumulation rates in mangrove coastal ecosystems, 14 C was used as long term chronological tracer, being useful in pristine mangrove forest reserve area. While in case of mangrove plantation of in coastal area, the 210 Pb is suitable for the estimation of decades scale estimation by its half-life. Though it has possibility of bio-/physical- turbation effect in applying 210 Pb chronology that is offset in case of 10 3 years scale estimation, especially in Asian mangrove ecosystem where the anthropogenic physical turbation by coastal fishery is vigorous.In this paper, we studied the organic carbon and 210 Pb accumulation rates in subtropical mangrove coastal ecosystems in Japan, Vietnam and Thailand with 7 Be analyses to make sure the negligible effect of above turbation effects on organic carbon accumulation. We finally concluded that 210 Pb was applicable to estimate organic carbon accumulation rates in these ecosystems even though the physical-/bio-turbation is expected. The measured organic carbon accumulation rates using 210 Pb in mangrove coastal ecosystems of Japan, Vietnam and Thailand were 0.067 4.0 t-C ha -1 y -1 . (author)

  14. Sediment and carbon deposition vary among vegetation assemblages in a coastal salt marsh

    Directory of Open Access Journals (Sweden)

    J. J. Kelleway

    2017-08-01

    Full Text Available Coastal salt marshes are dynamic, intertidal ecosystems that are increasingly being recognised for their contributions to ecosystem services, including carbon (C accumulation and storage. The survival of salt marshes and their capacity to store C under rising sea levels, however, is partially reliant upon sedimentation rates and influenced by a combination of physical and biological factors. In this study, we use several complementary methods to assess short-term (days deposition and medium-term (months accretion dynamics within a single marsh that contains three salt marsh vegetation types common throughout southeastern (SE Australia.We found that surface accretion varies among vegetation assemblages, with medium-term (19 months bulk accretion rates in the upper marsh rush (Juncus assemblage (1.74 ± 0.13 mm yr−1 consistently in excess of estimated local sea-level rise (1.15 mm yr−1. Accretion rates were lower and less consistent in both the succulent (Sarcocornia, 0.78 ± 0.18 mm yr−1 and grass (Sporobolus, 0.88 ± 0.22 mm yr−1 assemblages located lower in the tidal frame. Short-term (6 days experiments showed deposition within Juncus plots to be dominated by autochthonous organic inputs with C deposition rates ranging from 1.14 ± 0.41 mg C cm−2 d−1 (neap tidal period to 2.37 ± 0.44 mg C cm−2 d−1 (spring tidal period, while minerogenic inputs and lower C deposition dominated Sarcocornia (0.10 ± 0.02 to 0.62 ± 0.08 mg C cm−2 d−1 and Sporobolus (0.17 ± 0.04 to 0.40 ± 0.07 mg C cm−2 d−1 assemblages.Elemental (C : N, isotopic (δ13C, mid-infrared (MIR and 13C nuclear magnetic resonance (NMR analyses revealed little difference in either the source or character of materials being deposited among neap versus spring tidal periods. Instead, these analyses point to substantial redistribution of materials within the Sarcocornia and

  15. Assessing the relationship and influence of black carbon on distribution status of organochlorines in the coastal sediments from Pakistan

    International Nuclear Information System (INIS)

    Ali, Usman; Syed, Jabir Hussain; Junwen, Liu; Sánchez-García, Laura; Malik, Riffat Naseem; Chaudhry, Muhammad Jamshed Iqbal; Arshad, Masood; Li, Jun; Zhang, Gan; Jones, Kevin C.

    2014-01-01

    Levels of total organic carbon (TOC) and black carbon (BC) were determined together with those of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in the selected eighteen coastal sites (n = 285) along the Arabian Sea from Pakistan. Results showed that the total concentration of TOC, BC, ∑OCPs and ∑ 26 PCBs ranged between 0.3 and 2.9% dw, 0.1–0.2% dw, 0.9–110 ng g −1  dw and 6.2–1200 ng g −1  dw, respectively. Correlation analysis of BC (r = 0.26–0.89) and TOC (r = 0.06–0.69) revealed a stronger association with studied compounds. The sedimentary depositional fluxes (D) for ∑OCPs and ∑ 26 PCBs were calculated as 1.7 and 4.9 tons yr −1 , respectively. In the coastal belt of Pakistan, sedimentary mass inventories (I) indicated the presence of 13 and 37 metric tons of ∑OCPs and ∑ 26 PCBs, respectively. - Highlights: • First study to describe the sedimentary distribution of OCs and BC from coastal belt of Pakistan. • Higher levels of OCs and carbon contents were found in the sediments from Karachi coast. • Correlation analysis proved that BC has a significant impact on the fate and distribution of OCs in the study area. - Findings of the present study revealed that black carbon has a significant impact on the distribution of organochlorines in the coastal belt of Pakistan

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

    Science.gov (United States)

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

    2016-09-01

    Sulfate-reducing prokaryotes (SRPs) and antibiotic resistance genes (ARGs) in sediments could be biomarkers for evaluating the environmental impacts of human activities, although factors governing their distribution are not clear yet. By using metagenomic approach, this study investigated the distributions of SRPs and ARGs in marine sediments collected from 12 different coastal locations of Hong Kong, which exhibited different pollution levels and were classified into two groups based on sediment parameters. Our results showed that relative abundances of major SRP genera to total prokaryotes were consistently lower in the more seriously polluted sediments (P-value human impacts. Moreover, a unimodel distribution pattern for SRPs along with the pollution gradient was observed. Although total ARGs were enriched in sediments from the polluted sites, distribution of single major ARG types could be explained neither by individual sediment parameters nor by corresponding concentration of antibiotics. It supports the hypothesis that the persistence of ARGs in sediments may not need the selection of antibiotics. In summary, our study provided important hints of the niche differentiation of SRPs and behavior of ARGs in marine coastal sediment. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. Optimization of colorimetric DET technique for the in situ, two-dimensional measurement of iron(II) distributions in sediment porewaters

    DEFF Research Database (Denmark)

    Bennett, William W.; Teasdale, Peter R.; Welsh, David T.

    2012-01-01

    The recently developed colorimetric diffusive equilibration in thin films (DET) technique for the in situ, high-resolution measurement of iron(II) in marine sediments is optimized to allow measurement of the higher iron concentrations typical of freshwater sediment porewaters. Computer imaging...... the sensitivity of the assay as required; by processing the image with different color channel filters, the sensitivity of the assay can be optimized for lower concentrations (up to 100 μmol L -1) or higher concentrations (up to 2000 μmol L -1) of iron(II), depending on the specific site characteristics......(II) in sediment porewaters. The detection limit of the optimized technique was 4.1 ± 0.3 μmol L -1 iron(II) and relative standard deviations were less than 6%....

  18. Sediment-associated aliphatic and aromatic hydrocarbons in coastal British Columbia, Canada: Concentrations, composition, and associated risks to protected sea otters

    International Nuclear Information System (INIS)

    Harris, Kate A.; Yunker, Mark B.; Dangerfield, Neil; Ross, Peter S.

    2011-01-01

    Sediment-associated hydrocarbons can pose a risk to wildlife that rely on benthic marine food webs. We measured hydrocarbons in sediments from the habitat of protected sea otters in coastal British Columbia, Canada. Alkane concentrations were dominated by higher odd-chain n-alkanes at all sites, indicating terrestrial plant inputs. While remote sites were dominated by petrogenic polycyclic aromatic hydrocarbons (PAHs), small harbour sites within sea otter habitat and sites from an urban reference area reflected weathered petroleum and biomass and fossil fuel combustion. The partitioning of hydrocarbons between sediments and adjacent food webs provides an important exposure route for sea otters, as they consume ∼25% of their body weight per day in benthic invertebrates. Thus, exceedences of PAH sediment quality guidelines designed to protect aquatic biota at 20% of the sites in sea otter habitat suggest that sea otters are vulnerable to hydrocarbon contamination even in the absence of catastrophic oil spills. - Highlights: → Sediment hydrocarbon signatures differed between remote and impacted coastal sites. → A natural background comprised terrestrial plant alkanes and petrogenic PAHs. → Impacted sites reflected a history of petrogenic and pyrogenic hydrocarbon inputs. → Hydrocarbons at some sites exceeded guidelines for the protection of aquatic life. → Protected sea otters may thus be at risk as they rely primarily on benthic prey. - Anthropogenically-derived hydrocarbons in coastal sediments in British Columbia may pose a risk to protected sea otters.

  19. The effects of wastewater effluent and river discharge on benthic heterotrophic production, organic biomass and respiration in marine coastal sediments.

    Science.gov (United States)

    Burd, B; Macdonald, T; Bertold, S

    2013-09-15

    We examine effects of high river particulate flux and municipal wastewater effluent on heterotrophic organic carbon cycling in coastal subtidal sediments. Heterotrophic production was a predictable (r(2)=0.95) proportion (56%) of oxidized OC flux and strongly correlated with organic/inorganic flux. Consistent growth efficiencies (36%) occurred at all stations. Organic biomass was correlated with total, OC and buried OC fluxes, but not oxidized OC flux. Near the river, production was modest and biomass high, resulting in low P/B. Outfall deposition resulted in depleted biomass and high bacterial production, resulting in the highest P/B. These patterns explain why this region is production "saturated". The δ(15)N in outfall effluent, sediments and dominant taxa provided insight into where, and which types of organisms feed directly on fresh outfall particulates, on older, refractory material buried in sediments, or utilize chemosynthetic symbiotic bacteria. Results are discussed in the context of declining bottom oxygen conditions along the coast. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  20. Occurrence, distribution, and sources of emerging organic contaminants in tropical coastal sediments of anthropogenically impacted Klang River estuary, Malaysia.

    Science.gov (United States)

    Omar, Tuan Fauzan Tuan; Aris, Ahmad Zaharin; Yusoff, Fatimah Md; Mustafa, Shuhaimi

    2018-06-01

    This baseline assessment reports on the occurrence, distribution, and sources of emerging organic contaminants (EOCs) in tropical coastal sediments of anthropogenically impacted Klang River estuary, Malaysia. Bisphenol A was the highest concentration detected at 16.84 ng g -1 dry weight, followed by diclofenac (13.88 ng g -1 dry weight) and E1 (12.47 ng g -1 dry weight). Five compounds, namely, amoxicillin, progesterone, diazinon, bisphenol A, and E1, were found in all sampling stations assessed, and other compounds such as primidone, diclofenac, testosterone, E2, and EE2 were ubiquitously present in sediment samples, with percentage of detection range from 89.04% to 98.38%. Organic carbon content and pH were the important factors controlling the fate of targeted compounds in the tropical estuarine sediment. On the basis of the literature from other studies, the sources of EOCs are thought to be from wastewater treatment plants, domestic/medical waste discharge, livestock activities, industrial waste discharge, and agricultural activities. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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

  2. Mangroves and shoreline change on Molokai, Hawaii: Assessing the role of introduced Rhizophora mangle in sediment dynamics and coastal change using remote sensing and GIS

    Science.gov (United States)

    D'Iorio, Margaret Mary

    The Florida red mangrove, Rhizophora mangle, was introduced to the high volcanic island of Molokai, Hawaii in 1902 to trap sediment and stabilize eroding coastal mudflats along the island's reef-fringed south coast. This prolific invasive species now occupies 2.4 km2 of inter-tidal land and borders approximately 20% of the south coast shoreline. Integrating the fundamentals of remote sensing and Geographical Information Systems, this research investigates the effects of mangrove introduction on sediment dynamics and coastal change on south Molokai throughout the 20th century and provides a baseline of mangrove distribution, a detailed record of shoreline change rates, and a chronological history of island land use and environmental change. Monitoring of coastal change associated with mangroves is essential to understanding how natural coastal ecosystems react to alien species introductions and adapt overall to changing climatic regimes. Comparing the accuracy of various remote sensing instruments and processing techniques, this study has shown that the remote sensing with modern airborne and satellite sensors offers an effective management tool for mapping baseline conditions and monitoring change in remote island environments like that on the south coast of Molokai. Shoreline change assessment found that shoreline change rates on the island's south coast varied both alongshore and through time and that the dominant change has been one of progradation. Rates of change peaked in the early part of the 20th century and have since decayed exponentially over time. Changing land use practices coupled with the introduction of invasive species may have strongly influenced observed variability in rates of coastal change. Field observations and sediment analysis suggest that sediment transfer across the coastal boundary on the mangrove-fringed south coast is relatively limited and appears to be mainly event-driven. For shallow, reef-fringed, coastal regions vulnerable to

  3. Arsenic enrichment in shelf and coastal sediment of the Brazilian subtropics

    Science.gov (United States)

    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.

  4. Effects of nutrient loading on the carbon balance of coastal wetland sediments

    Science.gov (United States)

    Morris, J.T.; Bradley, P.M.

    1999-01-01

    Results of a 12-yr study in an oligotrophic South Carolina salt marsh demonstrate that soil respiration increased by 795 g C m-2 yr-1 and that carbon inventories decreased in sediments fertilized with nitrogen and phosphorus. Fertilized plots became net sources of carbon to the atmosphere, and sediment respiration continues in these plots at an accelerated pace. After 12 yr of treatment, soil macroorganic matter in the top 5 cm of sediment was 475 g C m-2 lower in fertilized plots than in controls, which is equivalent to a constant loss rate of 40 g C m-2 yr-1. It is not known whether soil carbon in fertilized plots has reached a new equilibrium or continues to decline. The increase in soil respiration in the fertilized plots was far greater than the loss of sediment organic matter, which indicates that the increase in soil respiration was largely due to an increase in primary production. Sediment respiration in laboratory incubations also demonstrated positive effects of nutrients. Thus, the results indicate that increased nutrient loading of oligotrophic wetlands can lead to an increased rate of sediment carbon turnover and a net loss of carbon from sediments.

  5. Plutonium in intertidal coastal and estuarine sediments in the Northern Irish Sea

    International Nuclear Information System (INIS)

    Aston, S.R.; Assinder, D.J.; Kelly, M.

    1985-01-01

    Surface intertidal sediments from 35 sites in the Irish Sea have been analysed for their 238 Pu and sup(239,240)Pu activities, together with an intensive study of plutonium in sediments of the Esk Estuary (NW England). The range of plutonium activities for the whole survey were 0.14-4118 and 1.3-16 026 Bq kg -1 for 238 Pu and sup(239,240)Pu, respectively. The levels of Pu activity, derived from the Sellafield nuclear fuel reprocessing effluents, in sediments are controlled by lithological factors and the influence of transport and post-depositional processes. Grain size distribution is particularly important, the major part of plutonium activity being in the mud fraction of all sediments. The data suggest that over the Irish Sea coastline, dynamic mixing of sediment grains by reworking and resuspension and/or by dispersion in tidal currents are important in determining plutonium distributions. The exponential decrease in sediment plutonium activities away from the Sellafield source is attributed to the progressive mixing with older contaminated and uncontaminated sediments. (author)

  6. Offshore sediments record the history of onshore iron ore mining in Goa State, India

    Digital Repository Service at National Institute of Oceanography (India)

    Sebastian, T.; Nath, B.N.; Naik, Sangeeta; Borole, D.V.; Pierre, S.; Yazing, A.K.

    Environmental magnetic and geochemical analyses combined with 210Pb dating were carried out on a sediment core off Goa from Arabian Sea to reconstruct the sedimentation history of last three and a half centuries and to investigate the impact...

  7. Sediment Biogeochemistry After the Entrance of Cable Bacteria

    DEFF Research Database (Denmark)

    Risgaard-Petersen, Nils

    fields which may strongly modify ionic transports. They form pH extremes, and accelerate the dissolution of iron sulfides, and carbonates in subsurface sediment. They further promote the formation of iron oxides and carbonates at the sediment surface and stimulate the removal of sulfides......, sulfide-rich coastal sediments, salt marshes seasonally hypoxic basins, subtidal coastal mud plains, as well as freshwater sediments and waterlogged soils. In this talk I will review our current knowledge on how cable bacteria influence the biogeochemistry of sediments. The cable bacteria form electric...... and the formation of sulfate[3] Field studies conducted in the marine environment indicate that some of these effects are expressed in a way that marine systems with active cable bacteria populations have elevated phosphorus-retention{Sulu-Gambari, 2016 #1501} and acts as strong buffers against adverse stage...

  8. Effects of artificial disturbance on quantity and biochemical composition of organic matter in sediments of a coastal lagoon

    Directory of Open Access Journals (Sweden)

    Lenzi M.

    2011-10-01

    Full Text Available The eutrophication of the coastal lagoon of Burano (Tuscany, Italy produces periodic toxic-anoxic events. The possibility of mitigating eutrophication of a lagoon by resuspension of sediment was tested in a three-year field experiment conducted in 2008–2009. An unreplicated before-after control-impact (BACI study design was used to ascertain variations in the quantity and biochemical composition of organic matter in sediment artificially disturbed by a specially equipped boat. In October 2008, before beginning disturbance, January 2009, half way through the disturbance period, and May 2009, at the end of disturbance, sediment was sampled in a disturbed area and an undisturbed control area to determine chlorophyll-a (Chl-a, phaeopigments (PHAE, proteins (PRT, carbohydrates (CHO, lipids (LIP, labile organic matter (LOM, refractory organic matter (ROM, total organic carbon (TOC and total nitrogen (TN. The disturbed area, measuring 44 ha, was divided into nine subareas, eight of which were subjected to four different frequencies of disturbance (from 2 to 5 in the period October 2008 – April 2009. Sediment was sampled in each sub-area in the three months mentioned above to determine labile and total organic matter. The results were processed by univariate and multivariate analysis using Primer 6.0, Permanova  +  and Prism 5.0 software. The findings were as follows: (1 a large proportion of the biopolymeric carbon consisted of labile matter throughout the lagoon; (2 higher abatement of labile organic matter was recorded in the disturbed area; (3 a lower protein:carbohydrate ratio was found in the disturbed than in the undisturbed area; (4 the C:N ratio of sediment was much lower in the undisturbed area than in the disturbed area at the end of the study period; (5 sediment and macroalgal C:N ratios did not significantly change in response to disturbance; (6 initial accumulation of organic matter from phytoplankton was greater in the disturbed

  9. Speciation of Co, Ni and Cu in the coastal and estuarine sediments: Some fundamental characteristics

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, P.

    provided a chemically significant description of the kinetics of metals–sediment interactions and correctly predicted the influences of ligand field stabilization energy (LFSE) and water exchange rate (k sub(-w)) on the dissociation rate constants of metals...

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

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G.A.P.

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

  11. Pleistocene coastal sedimentation in the north cliffs of Colonia del Sacramento

    International Nuclear Information System (INIS)

    Goso, C.; Perea, D.; Corona, A.; Mesa, V.

    2012-01-01

    This work is about the cliffs and the sucession of sandy and gravelly sediments in the north of Colonia city. The results obtained by thermoluminescence dating in sandy samples belong to the Quaternary period

  12. Bioprospecting Sediments from Red Sea Coastal Lagoons for Microorganisms and Their Antimicrobial Potential

    KAUST Repository

    Al Amoudi, Soha

    2016-01-01

    location with an increased probability of successful antibiotic bioprospecting, while the best sediment type in RHL for this purpose is microbial mat. Moreover, the phylum Actinobacteria tends to be the common target for research when it comes to antibiotic

  13. UV filters, ethylhexyl methoxycinnamate, octocrylene and ethylhexyl dimethyl PABA from untreated wastewater in sediment from eastern Mediterranean river transition and coastal zones.

    Science.gov (United States)

    Amine, Helmieh; Gomez, Elena; Halwani, Jalal; Casellas, Claude; Fenet, Hélène

    2012-11-01

    UVF may occur in the aquatic environment through two principal sources: direct inputs from recreational activities and indirect wastewater- and river-borne inputs. The aim of this study was to obtain a first overview of levels of three UVF (EHMC, OC and OD-PABA) in coastal areas subjected to river inputs, untreated wastewater discharges and dumpsite leachates. We selected three eastern Mediterranean rivers that have been impacted for decades by untreated wastewater release and collected sediment in the coastal zone during the hot and humid seasons. Western Mediterranean sites receiving treated wastewaters were analyzed for comparison. The results gave an overview of sediment contamination under these two contrasted situations representative of Mediterranean coastal areas without bathing activities. The analysis of the three UVF revealed the ubiquity and high point source contamination by EHMC and OC in transition and coastal zones, with levels as high as 128 ng g(-1)d.w. OD-PABA was also frequently detected, but at lower concentrations (sediment concentration in the dry period (August and October). Based on these results, we conclude that there is background contamination from river input that could be exacerbated by the direct contribution in coastal bathing zones. Copyright © 2012. Published by Elsevier Ltd.

  14. Impact of mussel bioengineering on fine-grained sediment dynamics in a coastal lagoon: A numerical modelling investigation

    Science.gov (United States)

    Forsberg, Pernille L.; Lumborg, Ulrik; Bundgaard, Klavs; Ernstsen, Verner B.

    2017-12-01

    Rødsand lagoon in southeast Denmark is a non-tidal coastal lagoon. It is home to a wide range of marine flora and fauna and part of the Natura 2000 network. An increase in turbidity through elevated levels of suspended sediment concentration (SSC) within the lagoon may affect the ecosystem health due to reduced light penetration. Increasing SSC levels within Rødsand lagoon could be caused by increasing storm intensity or by a sediment spill from dredging activities west of the lagoon in relation to the planned construction of the Fehmarnbelt fixed link between Denmark and Germany. The aim of the study was to investigate the impact of a mussel reef on sediment import and SSC in a semi-enclosed lagoon through the development of a bioengineering modelling application that makes it possible to include the filtrating effect of mussels in a numerical model of the lagoonal system. The numerical implementation of an exterior mussel reef generated a reduction in the SSC in the vicinity of the reef, through the adjacent inlet and in the western part of the lagoon. The mussel reef reduced the sediment import to Rødsand lagoon by 13-22% and reduced the SSC within Rødsand lagoon by 5-9% depending on the filtration rate and the reef length. The results suggest that the implementation of a mussel reef has the potential to relieve the pressure of increasing turbidity levels within a semi-enclosed lagoonal system. However, further assessment and development of the bioengineering application and resulting ecosystem impacts are necessary prior to actual implementation.

  15. Development and evaluation of a new diffusive gradients in thin-films technique for measuring organotin compounds in coastal sediment pore water

    DEFF Research Database (Denmark)

    Cole, Russell F.; Mills, Graham A.; Hale, Michelle S.

    2018-01-01

    in thin-films (DGT) adsorption gels to pre-concentrate five organotins (monobutlytin (MBT), dibutyltin (DBT), tributyltin (TBT), diphenyltin (DPhT), triphenyltin (TPhT)) found frequently in coastal sediment. C8 sorbent showed optimum performance in uptake and recovery of organotins for pH and ionic...

  16. Sulfide-induced release of phosphate from sediments of coastal lagoons and the possible relation to the disappearance of Ruppia sp

    NARCIS (Netherlands)

    Heijs, S.K.; Azzoni, R.; Giordani, G.; Jonkers, H.M.; Nizzoli, D.; Viaroli, P.; van Gemerden, H.

    2000-01-01

    The production and consumption of sulfide and its influence on phosphorous cycling were studied in a hypertrophic coastal lagoon (Valle Smarlacca, Italy). Oxygen measurements revealed that the water phase was supersaturated except for the layer directly overlying the sediment. This layer was devoid

  17. Sulfide-induced release of phosphate from sediments of coastal lagoons and the possible relation to the disappearance of Ruppia sp.

    NARCIS (Netherlands)

    Heijs, SK; Azzoni, R; Giordani, G; Jonkers, HM; Nizzoli, D; Viaroli, P; van Gemerden, H

    2000-01-01

    The production and consumption of sulfide and its influence on phosphorous cycling were studied in a hypertrophic coastal lagoon (Valle Smarlacca, Italy). Oxygen measurements revealed that the water phase was supersaturated except for the layer directly overlying the sediment. This layer was devoid

  18. Enhanced ocean carbon storage from anaerobic alkalinity generation in coastal sediments

    NARCIS (Netherlands)

    Thomas, H.; Schiettecatte, L.-S.; Suykens, K.; Koné, Y.J.M.; Shadwick, E.H.; Prowe, A.E.F.; Bozec, Y.; Baar, H.J.W. de; Borges, A.V.; Slomp, C.

    2009-01-01

    The coastal ocean is a crucial link between land, the open ocean and the atmosphere. The shallowness of the water column permits close interactions between the sedimentary, aquatic and atmospheric compartments, which otherwise are decoupled at long time scales (≅ 1000 yr) in the open oceans. Despite

  19. A Non-Equilibrium Sediment Transport Model for Coastal Inlets and Navigation Channels

    Science.gov (United States)

    2011-01-01

    combined, and therefore, there is one less partial differential equation to be solved. The short-term channel infilling and migration in two laboratory...oscillatory sheet flow: Experiments and bed load modeling. Coastal Engineering, 46(1), 61-87. Exner, F. M. 1925. Uber die Wechselwirkung zwischen

  20. Disentangling the complexity of nitrous oxide cycling in coastal sediments: Results from a novel multi-isotope approach

    Science.gov (United States)

    Wankel, S. D.; Buchwald, C.; Charoenpong, C.; Ziebis, W.

    2014-12-01

    Although marine environments contribute approximately 30% of the global atmospheric nitrous oxide (N2O) flux, coastal systems appear to comprise a disproportionately large majority of the ocean-atmosphere flux. However, there exists a wide range of estimates and future projections of N2O production and emission are confounded by spatial and temporal variability of biological sources and sinks. As N2O is produced as an intermediate in both oxidative and reductive microbial processes and can also be consumed as an electron acceptor, a mechanistic understanding of the regulation of these pathways remains poorly understood. To improve our understanding of N2O dynamics in coastal sediments, we conducted a series of intact flow-through sediment core incubations (Sylt, Germany), while manipulating both the O2 and NO3- concentrations in the overlying water. Steady-state natural abundance isotope fluxes (δ15N and δ18O) of nitrate, nitrite, ammonium and nitrous oxide were monitored throughout the experiments. We also measured both the isotopomer composition (site preference (SP) of the 15N in N2O) as well as the Δ17O composition in experiments conducted with the addition of NO3- with an elevated Δ17O composition (19.5‰), which provide complementary information about the processes producing and consuming N2O. Results indicate positive N2O fluxes (to the water column) across all conditions and sediment types. Decreasing dissolved O2 to 30% saturation resulted in reduced N2O fluxes (5.9 ± 6.5 μmol m2 d-1) compared to controls (17.8 ± 6.5 μmol m-2 d-1), while the addition of 100 μM NO3- yielded higher N2O fluxes (49.0 ± 18.5 μmol m-2 d-1). In all NO3- addition experiments, the Δ17O signal from the NO3- was clearly observed in the N2O efflux implicating denitrification as a large source of N2O. However, Δ17O values were always lower (1.9 to 8.6‰) than the starting NO3- indicating an important role for nitrification-based N2O production and/or O isotope exchange

  1. Distribution of petroleum hydrocarbons and organochlorinated contaminants in marine biota and coastal sediments from the ROPME Sea Area during 2005.

    Science.gov (United States)

    de Mora, Stephen; Tolosa, Imma; Fowler, Scott W; Villeneuve, Jean-Pierre; Cassi, Roberto; Cattini, Chantal

    2010-12-01

    The composition and spatial distribution of various petroleum hydrocarbons (PHs), comprising both aliphatic and polycyclic aromatic hydrocarbons (PAHs), and selected chlorinated pesticides and PCBs were measured in biota and coastal sediments from seven countries in the Persian Gulf and the Gulf of Oman (Bahrain, Iran, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates). Evidence of extensive marine contamination with respect to organochlorinated compounds and PHs was not observed. Only one site, namely the BAPCO oil refinery in Bahrain, was considered to be chronically contaminated. Comparison of the results from this survey for Σ DDTs and Σ PCBs in rock oysters from the Gulf of Oman with similar measurements made at the same locations over the past two decades indicates a temporal trend of overall decreasing Σ PCB concentrations in oysters, whereas Σ DDTs levels have little changed during that period. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Sedimentation separation and fluorescent X-ray analysis of very small amount of cobalt in pure iron

    International Nuclear Information System (INIS)

    Kato, Kensaku

    1990-01-01

    As the simple method of separation and analysis of very small amount of cobalt up to 1 ppm in pure iron, the application of sedimentation separation and fluorescent X-ray analysis was examined. By adding citric acid to the sample solution, the masking of the main components was carried out, and cobalt was deposited with 2-nitroso 1-naphtol separated and concentrated on a membrane filter. The reagents and equipments used are shown. The operation of the fundamental quantitative determination was determined. The condition of measurement, the condition of sedimentation separation, the effect of coexisting elements, the rate of recovery of cobalt, the calibration curve, and the analysis of actual samples are reported. By separating and concentrating cobalt on a membrane filter, this method eliminates the obstruction of coexisting elements to the object element, which is the problem in fluorescent X-ray measurement, and has the merit of simple operation and wide range of quantitative determination. (K.I.)

  3. 226Ra, 210Pb and 210Po levels in marine biota and surface coastal sediments from the Red sea, Sudan

    International Nuclear Information System (INIS)

    Sirelkhatim, D. A.; Sam, A. K.; Hassona, R. K.

    2003-01-01

    This paper presents data on 226 Ra, 210 Pb and 210 Po activity concentration levels in multicellular marine algae, molluscs, coral as well as in surface marine sediments collected from the shallower waters of the fringing reefs area extending towards north and south (flamingo bay) of Port Sudan harbour. The analyses were performed adopting a simple time efficient method combining alpha-spectrometry, liquid scintillation and Cerenkov counting technique. generally speaking, surface sediments from this coastal region are poor in their radioactivity content in contrast to similar data reported form different coastal areas around the globe. There is surface enrichment of 210 Pb and 210 Po with respect to their progenitor 226 Ra as it is evident form the activity ratios of 210 Pb/ 226 Ra (3.03±1.79) and 210 Pb/ 226 Ra (2.23±1.56). Among marine plants and animals investigated, the green algae species, Halimeda, and coral species, Favites, show substantial concentration of radium at 8.2 Bq/kg and 21.9 Bq/kg dry weight, respectively. Similarly, the highest concentration of 210 Po was met in the favites at 38.7 Bq/kg followed by brown algae, cytoseria sp., at 32.6 Bq/kg. There is no variation seen among algal species for 210 Pb uptake, however, converse to radium and polonium, favites (coral) was found to contain the minimum concentration of lead (3.88). In most species there is preferential accumulation of polonium over its parent radium as indicated by 210 Po: 226 Ra activity ratio with cytoseria (brown algae) showing the highest value at 8.81. On the other hand, 210 Po: 220 Pb activity concentration ratio revealed that coral species favites (9.97) and the brown algae sargassum (1.85) have a greater tendency to accumulate 210 Po over 220 Pb, while in the rest of the species; this ratio is less than unity. (Author)

  4. How sea level change mediates genetic divergence in coastal species across regions with varying tectonic and sediment processes.

    Science.gov (United States)

    Dolby, Greer A; Ellingson, Ryan A; Findley, Lloyd T; Jacobs, David K

    2018-02-01

    Plate tectonics and sediment processes control regional continental shelf topography. We examine the genetic consequences of how glacial-associated sea level change interacted with variable nearshore topography since the last glaciation. We reconstructed the size and distribution of areas suitable for tidal estuary formation from the last glacial maximum, ~20 thousand years ago, to present from San Francisco, California, USA (~38°N) to Reforma, Sinaloa, Mexico (~25°N). We assessed range-wide genetic structure and diversity of three codistributed tidal estuarine fishes (California Killifish, Shadow Goby, Longjaw Mudsucker) along ~4,600 km using mitochondrial control region and cytB sequence, and 16-20 microsatellite loci from a total of 524 individuals. Results show that glacial-associated sea level change limited estuarine habitat to few, widely separated refugia at glacial lowstand, and present-day genetic clades were sourced from specific refugia. Habitat increased during postglacial sea level rise and refugial populations admixed in newly formed habitats. Continental shelves with active tectonics and/or low sediment supply were steep and hosted fewer, smaller refugia with more genetically differentiated populations than on broader shelves. Approximate Bayesian computation favoured the refuge-recolonization scenarios from habitat models over isolation by distance and seaway alternatives, indicating isolation at lowstand is a major diversification mechanism among these estuarine (and perhaps other) coastal species. Because sea level change is a global phenomenon, we suggest this top-down physical control of extirpation-isolation-recolonization may be an important driver of genetic diversification in coastal taxa inhabiting other topographically complex coasts globally during the Mid- to Late Pleistocene and deeper timescales. © 2018 John Wiley & Sons Ltd.

  5. Late Pleistocene to Holocene environmental changes as recorded in the sulfur geochemistry of coastal plain sediments, southwestern Taiwan

    Science.gov (United States)

    Chen, Y.-G.; Liu, J.C.-L.; Shieh, Y.-N.; Liu, T.-K.

    2004-01-01

    A core, drilled at San-liao-wan in the southwestern coastal plain of Taiwan, has been analyzed for total sulfur contents, isotopic values, as well as ratios of pyritic sulfur to organic carbon. Our results demonstrate a close relationship between late Pleistocene sea-level change and the proxies generated in this study. The inorganic sulfur contents indicate that at our study site, the Holocene transgression started at ???11 ka and remained under seawater for thousands of years until the late Holocene, corresponding to a depth of 20 m in the study core. The uppermost 20 m of core shows relatively high total organic carbon (TOC) and ??34S of inorganic sulfur, suggesting a transitional environment such as muddy lagoon or marsh, before the site turned into a modern coastal plain. In the lower part of the core, at depths of 110-145 m (corresponding ages of ???12-30 ka), low sulfur contents are recorded, probably indicating fluvial sediments deposited during the oceanic isotope stage (OIS) 2, a sea-level lowstand. The lower part of the core, roughly within OIS 3, records at least two transgressions, although the transgressional signals may be somewhat obscured by subsequent weathering. The reworked origin of organic matter reported in previous studies is confirmed by our organic sulfur data; however, the marine organic source was periodically dominant. The modern high sulfate concentrations in pore water have no correlation to the other sulfur species in the sediments, probably indicating that the sulfate migrated into the site subsequent to early diagenesis. ?? 2003 Elsevier Ltd. All rights reserved.

  6. Health risk assessment linked to filling coastal quarries with treated dredged seaport sediments.

    Science.gov (United States)

    Perrodin, Yves; Donguy, Gilles; Emmanuel, Evens; Winiarski, Thierry

    2014-07-01

    Dredged seaport sediments raise complex management problems since it is no longer possible to discharge them into the sea. Traditional waste treatments are poorly adapted for these materials in terms of absorbable volumes and cost. In this context, filling quarries with treated sediments appears interesting but its safety regarding human health must be demonstrated. To achieve this, a specific methodology for assessing health risks has been developed and tested on three seaport sediments. This methodology includes the development of a conceptual model of the global scenario studied and the definition of specific protocols for each of its major steps. The approach proposed includes in particular the use of metrological and experimental tools that are new in this context: (i) an experimental lysimeter for characterizing the deposit emissions, and (ii) a geological radar for identifying potential preferential pathways between the sediment deposit and the groundwater. The application of this approach on the three sediments tested for the scenario studied showed the absence of health risk associated with the consumption of groundwater for substances having a "threshold effect" (risk quotient risk for substances having a "non-threshold effect", with the notable exception of arsenic (individual risk equal to 3.10(-6)). Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Hydrocarbon pollution in the sediment from the Jarzouna-Bizerte coastal area of Tunisia (Mediterranean Sea).

    Science.gov (United States)

    Zrafi-Nouira, I; Khedir-Ghenim, Z; Zrafi, F; Bahri, R; Cheraeif, I; Rouabhia, M; Saidane-Mosbahi, D

    2008-06-01

    This study investigated the presence and origin of hydrocarbon pollution in industrial waste water sediments found near the Jarzouna (Bizerte, Tunisia) oil refinery. Analyses of surface sediments (layer 1) and deep sediments (layer 2) showed that Total Hydrocarbon (TH) concentrations ranged from 602 +/- 7.638 microg/g in layer-1 to 1270 +/- 2.176 microg/g in layer-2. The results suggest that the deeper the sediment, the higher the level of total hydrocarbon found. The sedimentary Non Aromatic Hydrocarbon (NAH) and Aromatic Hydrocarbon (AH) concentrations ranged from 66.22 +/- 1.516 to 211.82 +/- 10.670 microg/g for NAH, and from 13.84 +/- 0.180 to 115.60 +/- 2.479 microg/g for AH. The high variability of these concentrations was associated with the location of the sediment collection sites. Aliphatic biomarker analysis revealed petroleum contamination close to the refinery rejection site, and biogenic sources further away. Petroleum contamination may be associated with increased industrial activity in the area of Jarzouna-Bizerte in the Mediterranean Sea.

  8. Redox oscillation affecting mercury mobility from highly contaminated coastal sediments: a mesocosm incubation experiment

    Directory of Open Access Journals (Sweden)

    Emili A.

    2013-04-01

    Full Text Available Mercury (Hg mobility at the sediment-water interface was investigated during a laboratory incubation experiment on highly contaminated sediments (up to 23 μg g−1 of the Gulf of Trieste. Undisturbed sediment was collected in front of the Isonzo River mouth, which inflows Hg-rich suspended material originating from the Idrija (NW Slovenia mining district. Since hypoxic and anoxic conditions at the bottom are frequently observed, a redox oscillation was simulated in the laboratory at in situ temperature, using a dark flux chamber. Temporal variations of several parameters were monitored simultaneously: dissolved Hg and methylmercury (MeHg, O2, NH4+, NO3−+NO2−, PO43−, H2S, dissolved Fe and Mn, dissolved inorganic and organic carbon (DIC and DOC. Benthic fluxes of Hg and MeHg were higher under anoxic conditions while re-oxygenation caused concentrations of MeHg and Hg to rapidly drop, probably due to re-adsorption onto Fe/Mn oxyhydroxides and enhanced demethylation. Hence, during anoxic events, sediments of the Gulf of Trieste may be considered as an important source of dissolved Hg species for the water column. However, re-oxygenation of the bottom compartment mitigates Hg and MeHg release from the sediment, thus acting as a natural “defence” from possible interaction between the metal and the aquatic organisms.

  9. The combined use of the PLHC-1 cell line and the recombinant yeast assay to assess the environmental quality of estuarine and coastal sediments.

    Science.gov (United States)

    Schnell, Sabine; Olivares, Alba; Piña, Benjamin; Echavarri-Erasun, Beatriz; Lacorte, Silvia; Porte, Cinta

    2013-12-15

    Sediment contamination poses a potential risk for both ecosystems and human health. Risk assessment is troublesome as sediments contain complex mixtures of toxicants, and traditional chemical analyses can neither provide information about potential hazards to organisms nor identify and measure all present contaminants. This work combines the use of the PLHC-1 cell line and the recombinant yeast assay (RYA) to assess the environmental quality of estuarine and coastal sediments. The application of multiple endpoints (cytotoxicity, generation of oxidative stress, presence of CYP1A inducing agents, micronucleus formation and estrogenicity) revealed that the organic extracts of those sediments affected by industrial activities or collected near harbours and untreated urban discharges showed significant cytotoxicity, micronuclei and CYP1A induction. The study highlights the usefulness of the applied bioassays to identify those sediments that could pose risk to aquatic organisms and that require further action to improve their environmental quality. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Environmental assessment of coastal surface sediments at Tarut Island, Arabian Gulf (Saudi Arabia).

    Science.gov (United States)

    Youssef, Mohamed; El-Sorogy, Abdelbaset; Al Kahtany, Khaled; Al Otiaby, Naif

    2015-07-15

    Thirty eight surface sediments samples have been collected in the area around Tarut Island, Saudi Arabian Gulf to determine the spatial distribution of metals, and to assess the magnitude of pollution. Total concentrations of Fe, Mn, As, B, Cd, Co, Cr, Cu, Hg, Mo, Pb, Se, and Zn in the sediments were measured using ICP-MS (Inductively Coupled Plasma-Mass Spectrometer). Nature of sediments and heavy metals distribution reflect marked changes in lithology, biological activities in Tarut bay. Very high arsenic concentrations were reported in all studied locations from Tarut Island. The concentrations of Mercury are generally high comparing to the reported values from the Gulf of Oman, Red Sea. The concentrations of As and Hg exceeded the wet threshold safety values (MEC, PEC) indicating possible As and Hg contamination. Dredging and land filling, sewage, and oil pollution are the most important sources of pollution in the study area. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Polycyclic Aromatic Hydrocarbons in Coastal Sediment of Klang Strait, Malaysia: Distribution Pattern, Risk Assessment and Sources

    Science.gov (United States)

    Tavakoly Sany, Seyedeh Belin; Hashim, Rosli; Salleh, Aishah; Rezayi, Majid; Mehdinia, Ali; Safari, Omid

    2014-01-01

    Concentration, source, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) were investigated in 22 stations from surface sediments in the areas of anthropogenic pollution in the Klang Strait (Malaysia). The total PAH level in the Klang Strait sediment was 994.02±918.1 µg/kg dw. The highest concentration was observed in stations near the coastline and mouth of the Klang River. These locations were dominated by high molecular weight PAHs. The results showed both pyrogenic and petrogenic sources are main sources of PAHs. Further analyses indicated that PAHs primarily originated from pyrogenic sources (coal combustion and vehicular emissions), with significant contribution from petroleum inputs. Regarding ecological risk estimation, only station 13 was moderately polluted, the rest of the stations suffered rare or slight adverse biological effects with PAH exposure in surface sediment, suggesting that PAHs are not considered as contaminants of concern in the Klang Strait. PMID:24747349

  12. Polycyclic aromatic hydrocarbons in coastal sediment of klang strait, Malaysia: distribution pattern, risk assessment and sources.

    Science.gov (United States)

    Tavakoly Sany, Seyedeh Belin; Hashim, Rosli; Salleh, Aishah; Rezayi, Majid; Mehdinia, Ali; Safari, Omid

    2014-01-01

    Concentration, source, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) were investigated in 22 stations from surface sediments in the areas of anthropogenic pollution in the Klang Strait (Malaysia). The total PAH level in the Klang Strait sediment was 994.02±918.1 µg/kg dw. The highest concentration was observed in stations near the coastline and mouth of the Klang River. These locations were dominated by high molecular weight PAHs. The results showed both pyrogenic and petrogenic sources are main sources of PAHs. Further analyses indicated that PAHs primarily originated from pyrogenic sources (coal combustion and vehicular emissions), with significant contribution from petroleum inputs. Regarding ecological risk estimation, only station 13 was moderately polluted, the rest of the stations suffered rare or slight adverse biological effects with PAH exposure in surface sediment, suggesting that PAHs are not considered as contaminants of concern in the Klang Strait.

  13. Polycyclic aromatic hydrocarbons in coastal sediment of klang strait, Malaysia: distribution pattern, risk assessment and sources.

    Directory of Open Access Journals (Sweden)

    Seyedeh Belin Tavakoly Sany

    Full Text Available Concentration, source, and ecological risk of polycyclic aromatic hydrocarbons (PAHs were investigated in 22 stations from surface sediments in the areas of anthropogenic pollution in the Klang Strait (Malaysia. The total PAH level in the Klang Strait sediment was 994.02±918.1 µg/kg dw. The highest concentration was observed in stations near the coastline and mouth of the Klang River. These locations were dominated by high molecular weight PAHs. The results showed both pyrogenic and petrogenic sources are main sources of PAHs. Further analyses indicated that PAHs primarily originated from pyrogenic sources (coal combustion and vehicular emissions, with significant contribution from petroleum inputs. Regarding ecological risk estimation, only station 13 was moderately polluted, the rest of the stations suffered rare or slight adverse biological effects with PAH exposure in surface sediment, suggesting that PAHs are not considered as contaminants of concern in the Klang Strait.

  14. Concentrations of some elements in the coastal sea sediments. Bays with marinas

    International Nuclear Information System (INIS)

    Obhodas, J.; Kutle, A.; Valkovic, V.

    2006-01-01

    Surface sediments and sediment cores from two bays in the Adriatic sea (Punat Bay and Soline Bay, Croatia) have been analyzed for a number of elements, in particular: Ti, V, Mn, Fe, Cu, Zn, As and Pb, by using XRF. Maps of elemental distribution in surface sediments show increased concentrations for some elements present in antifouling paints (Cu, Zn, Pb) near the service areas in the villages or marinas. Core profiles for these elements were used to evaluate the environmental impact of newly constructed marinas. Source partition indicates the influence of other sources located in near by villages. The critical factor in these considerations was shown to be water exchange with the open sea. (author)

  15. Health risk assessment linked to filling coastal quarries with treated dredged seaport sediments

    Energy Technology Data Exchange (ETDEWEB)

    Perrodin, Yves, E-mail: yves.perrodin@entpe.fr [Université de Lyon, ENTPE, UMR CNRS 5023, Laboratoire LEHNA, 2 rue Maurice Audin, 69518 Vaulx-en-Velin (France); Donguy, Gilles [Université de Lyon, ENTPE, UMR CNRS 5023, Laboratoire LEHNA, 2 rue Maurice Audin, 69518 Vaulx-en-Velin (France); Emmanuel, Evens [Laboratoire de Qualité de l' Eau et de l' Environnement, Université Quisqueya, BP 796 Port-au-Prince (Haiti); Winiarski, Thierry [Université de Lyon, ENTPE, UMR CNRS 5023, Laboratoire LEHNA, 2 rue Maurice Audin, 69518 Vaulx-en-Velin (France)

    2014-07-01

    Dredged seaport sediments raise complex management problems since it is no longer possible to discharge them into the sea. Traditional waste treatments are poorly adapted for these materials in terms of absorbable volumes and cost. In this context, filling quarries with treated sediments appears interesting but its safety regarding human health must be demonstrated. To achieve this, a specific methodology for assessing health risks has been developed and tested on three seaport sediments. This methodology includes the development of a conceptual model of the global scenario studied and the definition of specific protocols for each of its major steps. The approach proposed includes in particular the use of metrological and experimental tools that are new in this context: (i) an experimental lysimeter for characterizing the deposit emissions, and (ii) a geological radar for identifying potential preferential pathways between the sediment deposit and the groundwater. The application of this approach on the three sediments tested for the scenario studied showed the absence of health risk associated with the consumption of groundwater for substances having a “threshold effect” (risk quotient < 1), and an acceptable risk for substances having a “non-threshold effect”, with the notable exception of arsenic (individual risk equal to 3.10{sup −6}). - Highlights: • The release of polluted dredged seaport sediments into the sea must be avoided. • Their use after treatment for the filling-up of quarries is proposed by managers. • An original health risk assessment methodology was created to validate this option. • It includes the use of a lysimeter and a georadar for the exposure assessment stage. • The example studied concludes to a health risk linked to arsenic in the groundwater.

  16. Metal diagenesis and transport in coastal sediments around Penang Island, Malaysia

    International Nuclear Information System (INIS)

    Abd Khalik Wood; Zaharudin Ahmad; Noor Azhar Md Shazili; Rosnan Yaakob; Carpenter, R.

    2004-01-01

    Spatial and temporal variations in concentrations of several metals and isotopes in sediment cores from around Penang Island, an area with economically important biological resources off the northwest coast of peninsular Malaysia, are reported. Because of a typical, monazite rich mineralogy in surrounding drainage basins, sedimentary metal enrichment factors relative to global average materials, enrichment factors (EFs) of >1.0 do not always indicate significant anthropogenic metal inputs. Because of extensive metal solubilization in the hot, organic carbon rich area, EFs of < 1.0 may be observed for several metals despite significant anthropogenic contributions. Comparison of metal-Al relationships in Penang area surface sediments with those in nearby and presumed uncontaminated Strait of Malacca sediments more accurately correct for atypical regional solubilization and mineralogical effects than comparison to global average materials. Such comparisons show concentrations of Cd, Cu, Pb, Ni, Cr, As, Sb, Zn and V have changed by less than a factor of two by anthropogenic discharges. Sedimentary concentration profiles of Pb, Zn and Cu, ratioed to Sc to normalize for variations in grain size and mineralogy, have subsurface maxima suggestive of modest and recently reduced anthropogenic inputs. Mn, U, As and Sb have Sc-normalized concentration profiles clearly affected by digenetic processes. Sc-normalized profiles of Cr, Th, Ce and Sm show only small changes with depth, confirming insignificant anthropogenic inputs and undetectable post depositional digenetic mobility. Excess 210-Pb activities and fluxes in Penang area sediments are limited by supply of this radionuclide, in contrast to sediments of both the northwestern USA. and Amazon continental shelves, where they are limited by particle scavenging reactions. 210-Pb activities in sediments of the shallow, dynamic Penang area often show erratic or unconvincing changes with depth that cannot be reliably modeled by

  17. Health risk assessment linked to filling coastal quarries with treated dredged seaport sediments

    International Nuclear Information System (INIS)

    Perrodin, Yves; Donguy, Gilles; Emmanuel, Evens; Winiarski, Thierry

    2014-01-01

    Dredged seaport sediments raise complex management problems since it is no longer possible to discharge them into the sea. Traditional waste treatments are poorly adapted for these materials in terms of absorbable volumes and cost. In this context, filling quarries with treated sediments appears interesting but its safety regarding human health must be demonstrated. To achieve this, a specific methodology for assessing health risks has been developed and tested on three seaport sediments. This methodology includes the development of a conceptual model of the global scenario studied and the definition of specific protocols for each of its major steps. The approach proposed includes in particular the use of metrological and experimental tools that are new in this context: (i) an experimental lysimeter for characterizing the deposit emissions, and (ii) a geological radar for identifying potential preferential pathways between the sediment deposit and the groundwater. The application of this approach on the three sediments tested for the scenario studied showed the absence of health risk associated with the consumption of groundwater for substances having a “threshold effect” (risk quotient −6 ). - Highlights: • The release of polluted dredged seaport sediments into the sea must be avoided. • Their use after treatment for the filling-up of quarries is proposed by managers. • An original health risk assessment methodology was created to validate this option. • It includes the use of a lysimeter and a georadar for the exposure assessment stage. • The example studied concludes to a health risk linked to arsenic in the groundwater

  18. Occurrence of microplastics in the coastal marine environment: First observation on sediment of China.

    Science.gov (United States)

    Qiu, Qiongxuan; Peng, Jinping; Yu, Xubiao; Chen, Fangchaizi; Wang, Jundong; Dong, Fenqiang

    2015-09-15

    Microplastics in sediments from the Beibu Gulf and the coastline of China Sea were investigated to evaluate the occurrence and abundance of microplastics in China for the first time. Microplastics (microplastics was counted by a fluorescence microscope, an instrument that is rarely used in the detection of microplastics in sediments. This instrument led to results that were satisfactory. Compared with other sampled areas, microplastics were found in massive concentrations in China. Four types of microplastics, HDPE, PET, PE and PS, were identified. The results will provide useful background information for further investigations. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Rapid coastal survey of anthropogenic radionuclides, metals, and organic compounds in surficial marine sediments

    International Nuclear Information System (INIS)

    Noakes, J.E.; Noakes, S.E.; Dvoracek, D.K.; Culp, R.A.; Bush, P.B.

    1999-01-01

    A towed survey system, the GIMS/CS 3 , has been developed to enable the rapid measurement and mapping of a variety of physical and geochemical parameters in the surficial sediments of aquatic environments while the survey vessel is underway. With its capability for measuring radiometric, elemental and organic compound constituents of sediments, as well as bathymetry and water quality parameters, the GIMS/CS 3 provides a cost-effective means of performing reconnaissance determinations of contaminant distributions and environmental monitoring tasks over broad geographic regions

  20. Shifts in coastal sediment oxygenation cause pronounced changes in microbial community composition and associated metabolism

    DEFF Research Database (Denmark)

    Broman, Elias; Sjöstedt, Johanna; Pinhassi, Jarone

    2017-01-01

    . In particular, the intermediate site sediments responded differently upon oxygenation compared to the anoxic and oxic site sediments. This included a microbial community composition with more habitat generalists, lower amounts of RNA transcripts attributed to methane oxidation, and a reduced rate of organic...... efforts, depend largely on the oxygenation history of sites. Furthermore, it was shown that re-oxygenation efforts to remediate dead zones could ultimately be facilitated by in situ microbial molecular mechanisms involved in removal of toxic H2S and the potent greenhouse gas methane....

  1. Early diagenesis of manganese, iron and phosphorus in European continental margin sediments

    NARCIS (Netherlands)

    Zee, C. van der

    2002-01-01

    This thesis describes the results of a project that was carried out as a part of the Sedimentary Manganese and Iron cycLEs (SMILE) research program funded by the Netherlands Organisation of Scientific Research (NWO/ALW). SMILE aimed at studying the biogeochemistry of iron and manganese cycles in

  2. Early diagenesis of Manganese, Iron and Phosphorus in European continental margin sediments

    NARCIS (Netherlands)

    van der Zee, C.

    2002-01-01

    This thesis describes the results of a project that was carried out as a part of the Sedimentary Manganese and Iron cycLEs (SMILE) research program funded by the Netherlands Organisation of Scientific Research (NWO/ALW). SMILE aimed at studying the biogeochemistry of iron and manganese cycles in

  3. Iron

    DEFF Research Database (Denmark)

    Hansen, Jakob Bondo; Moen, I W; Mandrup-Poulsen, T

    2014-01-01

    and discuss recent evidence, suggesting that iron is a key pathogenic factor in both type 1 and type 2 diabetes with a focus on inflammatory pathways. Pro-inflammatory cytokine-induced β-cell death is not fully understood, but may include iron-induced ROS formation resulting in dedifferentiation by activation...... of transcription factors, activation of the mitochondrial apoptotic machinery or of other cell death mechanisms. The pro-inflammatory cytokine IL-1β facilitates divalent metal transporter 1 (DMT1)-induced β-cell iron uptake and consequently ROS formation and apoptosis, and we propose that this mechanism provides...

  4. Vertical Existence of Coprostanol in a Sediment Core From Semarang Coastal Waters, Central Java, Indonesia

    OpenAIRE

    Bachtiar, Tonny

    2004-01-01

    Coprostanol has been proposed as an indicator of domestic (sewage) pollution by researchers because constraint of using coliform bacteria as the indicators of domestic pollution in the environment with high environmental stress, such as urban coastal waters. Increasing the volume of industrial wastes, toxic and heated, the changing of water salinity from low (freshwater) to high (sea water), and decreasing of dissolved oxygen (DO) in the waters, are the constrain factors of bacteria growth. ...

  5. [Simulated study of algal fatty acid degradation in hypoxia seawater-sediment interface along China coastal area].

    Science.gov (United States)

    Sui, Wei-Wei; Ding, Hai-Bing; Yang, Gui-Peng; Lu, Xiao-Lan; Li, Wen-Juan; Sun, Li-Qun

    2013-11-01

    Series of laboratory incubation experiments were conducted to simulate degradation of organic matter in sediment-seawater interface in hypoxia enviroments along China coastal area. Under four different redox conditions (oxygen saturation: 100%, 50%, 25% and 0%), degradations of seveal biomarkers originated from Skeletonema costatum, a typical red tide alage along China coastal area were tracked. By analyzing concentrations of four fatty acid biomarkers [14:0, 16:0, 16:1(7) and 20:5] obtained at various sampling time, results showed that their concentrations decreased significantly after 2-3 weeks' incubation. Then, their concentrations changed very slowly or very little. However, degradation of the four fatty acids varied dramatically in different incubation systems. Fatty acids 14:0, 16:1(7) and 20:5 were degraded completely in all incubation systems after two-month incubation, but 25% to 35% of 16:0 was reserved in the systems. Based on multi-G model, degradations of the four fatty acids were quantively described. The results indicated that all four fatty acids had fast-degraded and slow-degraded fractions. Their degradation rate constants (k(av)) ranged from 0.079 to 0.84 d(-1). The fastest degradation of 14:0 and 16:1 (7) occurred under 25% oxygen concentrations. For these two compounds, in the fastest degradation system, their k(av), values were 2.3 folds and 1.7 folds higher than those in the slowest degradation system [50% oxygen saturation for 14:0 and 100% oxygen saturation for 16:1(7)] respectively. The 16:0 was degraded fastest under the anoxic condition and slowest under the 50% oxygen saturation. The ratio of the two k(av)s was 2.1. The k(av)s of 20:5 had a positive relationship with oxygen saturations. Results of this study suggested that besides oxgen saturations, structure and features of organic compounds, roles of microbe in the envrioments and etc. might affect degradations of fatty acids in S. costatum in hypoxia sediment-seawater interface

  6. APPLICATION OF MAGNETIC SURVEY TO EXPLORE THE IRON ORE DEPOSITS IN THE NUSAWUNGU COASTAL REGENCY OF CILACAP CENTRAL JAVA

    Directory of Open Access Journals (Sweden)

    S Sehah

    2017-12-01

    Full Text Available The research aiming to explore the iron ore deposits in the Nusawungu coastal Regency of Cilacap has been conducted using the magnetic survey. The acquisition of magnetic data was conducted in April – Mei 2017, covering the area in the ranges of 109.314° – 109.345°E and 7.691° – 7.709°S. The obtained magnetic field strength data were corrected, reduced, and mapped to obtain the contour map of local magnetic anomaly. The modeling process was carried out along the path extending over the map from the positions of 109.314°E and 7.695°S to 109.335°E and 7.699°S, so that some subsurface anomalous objects are obtained. The lithological interpretation was performed to identify the types of subsurface rocks and their formations based on the magnetic susceptibility value of each anomalous objects and supported by the geological information of the research area. Based on the interpretation results, three rocks deposits of alluvium formations were obtained, which are estimated to contain iron ore. The first deposit has a length of 164.85 m, a depth of 0.57 – 8.43 m, and a magnetic susceptibility value of 0.0097 cgs. The second deposit has a length of 376.28 m, a depth of 2.56 – 19.66 m, and a magnetic susceptibility value of 0.0108 cgs. The third deposit has a length of 1,306.26 m, a depth of 3.70 – 58.69 m, and a magnetic susceptibility value of 0.0235 cgs. Out of the whole rocks deposits, the third rock deposit is interpreted to have the most prospective iron ore. This interpretation based on its high magnetic susceptibility value, which indicates the presence of many magnetic minerals (i.e. iron ores in the rock.

  7. Iron

    Science.gov (United States)

    ... Share: Search the ODS website Submit Search NIH Office of Dietary Supplements Consumer Datos en español Health ... eating a variety of foods, including the following: Lean meat, seafood, and poultry. Iron-fortified breakfast cereals ...

  8. Uranium series disequilibrium in the coastal surface sediments and sea water of the Arabian sea

    Digital Repository Service at National Institute of Oceanography (India)

    Joshi, L.U.; Zingde, M.D.

    activity ratios in leachates, and residues after removal of surface organic matter from the sediment particles by treatment with hydrogen peroxide and 0.05M HCl, revealed disequilibrium between sup(238) U and sup(234) U only in the surface organic matter...

  9. Fine sediment sources in coastal watersheds with uplifted marine terraces in northwest Humboldt County, California

    Science.gov (United States)

    Stephen Sungnome Madrone; Andrew P. Stubblefield

    2012-01-01

    Erosion in the Mill and Luffenholtz Creek watersheds in Humboldt County, California, with their extensive clay soils, can lead to high turbidity levels in receiving bodies of water, increasing the costs of treating water for domestic water supplies. Detailed road and erosion surveys and monitoring of suspended sediment, discharge, and turbidity levels in Mill Creek (3....

  10. Geochemical characterisation of major and trace elements in the coastal sediments of India

    Digital Repository Service at National Institute of Oceanography (India)

    Alagarsamy, R.; Zhang, J.

    . Metal enrichments observed close to the major urban areas in the east and west coasts are associated with the industrialised activities areas rich in Cu and Co in both the east and west coast sediments. Normalisation of metals to Al indicated that high...

  11. Sedimentation across the central California oxygen minimum zone: an alternative coastal upwelling sequence.

    Science.gov (United States)

    Vercoutere, T.L.; Mullins, H.T.; McDougall, K.; Thompson, J.B.

    1987-01-01

    Distribution, abundance, and diversity of terrigenous, authigenous, and biogenous material provide evidence of the effect of bottom currents and oxygen minimum zone (OMZ) on continental slope sedimentation offshore central California. Three major OMZ facies are identified, along the upper and lower edges of OMZ and one at its core.-from Authors

  12. Effect of redox conditions on bacterial and fungal biomass and carbon dioxide production in Louisiana coastal swamp forest sediment

    International Nuclear Information System (INIS)

    Seo, Dong Cheol; DeLaune, Ronald D.

    2010-01-01

    Fungal and bacterial carbon dioxide (CO 2 ) production/emission was determined under a range of redox conditions in sediment from a Louisiana swamp forest used for wastewater treatment. Sediment was incubated in microcosms at 6 Eh levels (-200, -100, 0, + 100, + 250 and + 400 mV) covering the anaerobic range found in wetland soil and sediment. Carbon dioxide production was determined by the substrate-induced respiration (SIR) inhibition method. Cycloheximide (C 15 H 23 NO 4 ) was used as the fungal inhibitor and streptomycin (C 21 H 39 N 7 O 12 ) as the bacterial inhibitor. Under moderately reducing conditions (Eh > + 250 mV), fungi contributed more than bacteria to the CO 2 production. Under highly reducing conditions (Eh ≤ 0 mV), bacteria contributed more than fungi to the total CO 2 production. The fungi/bacteria (F/B) ratios varied between 0.71-1.16 for microbial biomass C, and 0.54-0.94 for microbial biomass N. Under moderately reducing conditions (Eh ≥ + 100 mV), the F/B ratios for microbial biomass C and N were higher than that for highly reducing conditions (Eh ≤ 0 mV). In moderately reducing conditions (Eh ≥ + 100 mV), the C/N microbial biomass ratio for fungi (C/N: 13.54-14.26) was slightly higher than for bacteria (C/N: 9.61-12.07). Under highly reducing redox conditions (Eh ≤ 0 mV), the C/N microbial biomass ratio for fungi (C/N: 10.79-12.41) was higher than for bacteria (C/N: 8.21-9.14). For bacteria and fungi, the C/N microbial biomass ratios under moderately reducing conditions were higher than that in highly reducing conditions. Fungal CO 2 production from swamp forest could be of greater ecological significance under moderately reducing sediment conditions contributing to the greenhouse effect (GHE) and the global warming potential (GWP). However, increases in coastal submergence associated with global sea level rise and resultant decrease in sediment redox potential from increased flooding would likely shift CO 2 production to bacteria

  13. Imprint of past and present environmental conditions on microbiology and biogeochemistry of coastal Quaternary sediments

    Directory of Open Access Journals (Sweden)

    M. Beck

    2011-01-01

    Full Text Available To date, North Sea tidal-flat sediments have been intensively studied down to a depth of 5 m below seafloor (mbsf. However, little is known about the biogeochemistry, microbial abundance, and activity of sulfate reducers as well as methanogens in deeper layers. In this study, two 20 m-long cores were retrieved from the tidal-flat area of Spiekeroog Island, NW Germany. The drill sites were selected with a close distance of 900 m allowing to compare two depositional settings: first, a paleo-channel filled with Holocene sediments and second, a mainly Pleistocene sedimentary succession. Analyzing these cores, we wanted to test to which degree the paleo-environmental imprint is superimposed by present processes.

    In general, the numbers of bacterial 16S rRNA genes are one to two orders of magnitude higher than those of Archaea. The abundances of key genes for sulfate reduction and methanogenesis (dsrA and mcrA correspond to the sulfate and methane profiles. A co-variance of these key genes at sulfate-methane interfaces and enhanced ex situ AOM rates suggest that anaerobic oxidation of methane may occur in these layers. Microbial and biogeochemical profiles are vertically stretched relative to 5 m-deep cores from shallower sediments in the same study area, but still appear compressed compared to deep sea sediments. Our interdisciplinary analysis shows that the microbial abundances and metabolic rates are elevated in the Holocene compared to Pleistocene sediments. However, this is mainly due to present environmental conditions such as pore water flow and organic matter availability. The paleo-environmental imprint is still visible but superimposed by these processes.

  14. Anthropogenic impact on the sedimentation in coastal regions: an example in Saco do Bracui - Ribeira Bay, Angra dos Reis, Brazil

    International Nuclear Information System (INIS)

    Barbosa, Alayde Alfaia

    2001-01-01

    The Saco do Bracui, located in the littoral zone of the Brazilian southeast, receives run off from the region of Angra dos Reis. Anthropological intervention in this area has modified local morphology during the last 40 years. These modifications include an intense deforestation of mangrove regions, construction of the Bracui Boat Yard, the dredging of part of the draining basin and development of the coastal plain. Results from seismic surveys identify three different stratigraphic units separated by two reflectors as well as Holocenic paleodeltas and paleochannels of the Bracui and Gratau rivers. Results from this study and previous work indicate an age of 6800 years for the top of the superior unit. Areal photographs from the years 1964, 1965, 1978 and 1991 reveal the principal modifications occurring during the last 40 years in the area. Field observations from this study as well as bathymetric profiles based on the nautical maps of 1980 and 1944 reveal shoaling and erosion areas in the Saco do Bracui. Sedimentation rates, using lead-210 profiles, are between 0,17 - 1,90 cm/year and lead-210 inventory values are between 16-6-dpm/cm 2 /year. The results for sedimentation rate and inventory show a high accumulation around Bracui, Gratau and Frade mouth rivers and agree with results from the bathymetric profiles with respect to the site of erosion and shoaling in the Saco do Bracui. The results for grain size and lead-210 analyses support the idea that the Saco do Bracui is suffering shoaling processes in specific sites and erosion in others. Comparison between long term sedimentation rates obtained by seismic results and short term rates obtained by lead-210 shows an increase of the sedimentary discharge in the 1960's, when the intense anthropological intervention in the area began. (author)

  15. Redox-Stratified Bacterial Communities in Sediments Associated with Multiple Lucinid Bivalve Species: Implications for Symbiosis in Changing Coastal Habitats

    Science.gov (United States)

    Paterson, A. T.; Fortier, C. M.; Long, B.; Kokesh, B. S.; Lim, S. J.; Campbell, B. J.; Anderson, L. C.; Engel, A. S.

    2017-12-01

    Lucinids, chemosymbiotic marine bivalves, occupy strong redox gradient habitats, including the rhizosphere of coastal seagrass beds and mangrove forests in subtropical to tropical ecosystems. Lucinids and their sulfide-oxidizing gammaproteobacterial endosymbionts, which are acquired from the environment, provide a critical ecosystem service by removing toxic reduced sulfur compounds from the surrounding environment, and lucinids may be an important food source to economically valuable fisheries. The habitats of Phacoides pectinatus, Stewartia floridana, Codakia orbicularis, Ctena orbiculata, and Lucina pensylvanica lucinids in Florida and San Salvador in The Bahamas were evaluated in comprehensive malacological, microbiological, and geochemical surveys. Vegetation cover included different seagrass species or calcareous green macroalgae. All sites were variably affected by anthropogenic activities, as evidenced by visible prop scars in seagrass beds, grain size distributions atypical of low energy environments (i.e., artificial fill or dredge material from nearby channels), and high levels of pyrogenic hydrocarbon compounds in sediment indicative of urbanization impact. Where present, lucinid population densities frequently exceeded 2000 individuals per cubic meter, and were typically more abundant underlying seagrass compared to unvegetated, bare sand. Dissolved oxygen and sulfide levels varied from where lucinids were recovered. The sediment bacterial communities from classified 16S rRNA gene sequences indicated that the diversity of putative anaerobic groups increased with sediment depth, but putative aerobes, including of Gammaproteobacteria related to the lucinid endosymbionts, decreased with depth. Where multiple seagrass species co-occurred, retrieved bacterial community compositions correlated to overlying seagrass species, but diversity differed from bare sand patches, including among putative free-living endosymbiont groups. As such, continued sea

  16. Sediment transport patterns in the San Francisco Bay Coastal System from cross-validation of bedform asymmetry and modeled residual flux

    Science.gov (United States)

    Barnard, Patrick L.; Erikson, Li H.; Elias, Edwin P.L.; Dartnell, Peter; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.

    2013-01-01

    The morphology of ~ 45,000 bedforms from 13 multibeam bathymetry surveys was used as a proxy for identifying net bedload sediment transport directions and pathways throughout the San Francisco Bay estuary and adjacent outer coast. The spatially-averaged shape asymmetry of the bedforms reveals distinct pathways of ebb and flood transport. Additionally, the region-wide, ebb-oriented asymmetry of 5% suggests net seaward-directed transport within the estuarine-coastal system, with significant seaward asymmetry at the mouth of San Francisco Bay (11%), through the northern reaches of the Bay (7–8%), and among the largest bedforms (21% for λ > 50 m). This general indication for the net transport of sand to the open coast strongly suggests that anthropogenic removal of sediment from the estuary, particularly along clearly defined seaward transport pathways, will limit the supply of sand to chronically eroding, open-coast beaches. The bedform asymmetry measurements significantly agree (up to ~ 76%) with modeled annual residual transport directions derived from a hydrodynamically-calibrated numerical model, and the orientation of adjacent, flow-sculpted seafloor features such as mega-flute structures, providing a comprehensive validation of the technique. The methods described in this paper to determine well-defined, cross-validated sediment transport pathways can be applied to estuarine-coastal systems globally where bedforms are present. The results can inform and improve regional sediment management practices to more efficiently utilize often limited sediment resources and mitigate current and future sediment supply-related impacts.

  17. Are conventional statistical techniques exhaustive for defining metal background concentrations in harbour sediments? A case study: The Coastal Area of Bari (Southeast Italy).

    Science.gov (United States)

    Mali, Matilda; Dell'Anna, Maria Michela; Mastrorilli, Piero; Damiani, Leonardo; Ungaro, Nicola; Belviso, Claudia; Fiore, Saverio

    2015-11-01

    Sediment contamination by metals poses significant risks to coastal ecosystems and is considered to be problematic for dredging operations. The determination of the background values of metal and metalloid distribution based on site-specific variability is fundamental in assessing pollution levels in harbour sediments. The novelty of the present work consists of addressing the scope and limitation of analysing port sediments through the use of conventional statistical techniques (such as: linear regression analysis, construction of cumulative frequency curves and the iterative 2σ technique), that are commonly employed for assessing Regional Geochemical Background (RGB) values in coastal sediments. This study ascertained that although the tout court use of such techniques in determining the RGB values in harbour sediments seems appropriate (the chemical-physical parameters of port sediments fit well with statistical equations), it should nevertheless be avoided because it may be misleading and can mask key aspects of the study area that can only be revealed by further investigations, such as mineralogical and multivariate statistical analyses. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Environmental evolution records reflected by radionuclides in the sediment of coastal wetlands: A case study in the Yellow River Estuary wetland.

    Science.gov (United States)

    Wang, Qidong; Song, Jinming; Li, Xuegang; Yuan, Huamao; Li, Ning; Cao, Lei

    2016-10-01

    Vertical profiles of environmental radionuclides ( 210 Pb, 137 Cs, 238 U, 232 Th, 226 Ra and 4 0 K) in a sediment core (Y1) of the Yellow River Estuary wetland were investigated to assess whether environmental evolutions in the coastal wetland could be recorded by the distributions of radionuclides. Based on 210 Pb and 137 Cs dating, the average sedimentation rate of core Y1 was estimated to be 1.0 cm y -1 . Vertical distributions of natural radionuclides ( 238 U, 232 Th, 226 Ra and 40 K) changed dramatically, reflecting great changes in sediment input. Concentrations of 238 U, 232 Th, 226 Ra and 40 K all had significant positive relationships with organic matter and clay content, but their distributions were determined by different factors. Factor analysis showed that 238 U was determined by the river sediment input while 226 Ra was mainly affected by the seawater erosion. Environmental changes such as river channel migrations and sediment discharge variations could always cause changes in the concentrations of radionuclides. High concentrations of 238 U and 226 Ra were consistent with high accretion rate. Frequent seawater intrusion decreased the concentration of 226 Ra significantly. The value of 238 U/ 226 Ra tended to be higher when the sedimentation rate was low and tide intrusion was frequent. In summary, environmental evolutions in the estuary coastal wetland could be recorded by the vertical profiles of natural radionuclides. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Coastal Dynamics

    NARCIS (Netherlands)

    Roelvink, J.A.; Steetzel, H.J.; Bliek, A.; Rakhorst, H.D.; Roelse, P.; Bakker, W.T.

    1998-01-01

    This book deals on "Coastal Dynamics", which will be defined in a narrow sense as a mathematical theory, which starts from given equations of motion for the sediment, which leads with the continuity equation and given boundary conditions to a calculated (eventually schematized) coastal topography,

  20. Arsenic and trace metals in river water and sediments from the southeast portion of the Iron Quadrangle, Brazil.

    Science.gov (United States)

    Varejão, Eduardo V V; Bellato, Carlos R; Fontes, Maurício P F; Mello, Jaime W V

    2011-01-01

    The Iron Quadrangle has been one of the most important gold production regions in Brazil since the end of the seventeenth century. There, arsenic occurs in close association with sulfide-rich auriferous rocks. The most abundant sulfide minerals are pyrite and arsenopyrite, yet trace metal sulfides occur in subordinate phases as well. Historical mining activities have been responsible for the release of As and trace metals to both aquatic and terrestrial environments close to mining sites in the region. Therefore, this study was aimed to evaluate the distribution and mobility of As, Cd, Co, Cr, Cu, Ni, Pb, and Zn in streams in the southeast portion of the Iron Quadrangle between the municipalities of Ouro Preto and Mariana, the oldest Brazilian Au mining province. Total concentrations of some trace metals and arsenic in water were determined. The four-stage sequential extraction procedure proposed by the commission of the European Communities Bureau of Reference (BCR) was used to investigate the distribution of these elements in stream sediments. Arsenic concentration in water was > 10 μg L⁻¹ (maximum limit permitted by Brazilian environmental regulations for water destined for human consumption) at all sampling sites, varying between 36.7 and 68.3 μg L⁻¹. Sequential extraction in sediments showed high concentrations of As and trace metals associated with easily mobilized fractions.

  1. Effects of thiamphenicol on nitrate reduction and N2O release in estuarine and coastal sediments

    International Nuclear Information System (INIS)

    Yin, Guoyu; Hou, Lijun; Liu, Min; Zheng, Yanling; Li, Xiaofei; Lin, Xianbiao; Gao, Juan; Jiang, Xiaofen

    2016-01-01

    Nitrate overload is an important driver of water pollution in most estuarine and coastal ecosystems, and thus nitrate reduction processes have attracted considerable attention. Antibiotics contamination is also an emerging environmental problem in estuarine and coastal regions as a result of growing production and usage of antibiotics. However, the effects of antibiotics on nitrate reduction remain unclear in these aquatic ecosystems. In this study, continuous-flow experiments were conducted to examine the effects of thiamphenicol (TAP, a common chloramphenicol antibiotic) on nitrate reduction and greenhouse gas N 2 O release. Functional genes involved in nitrogen transformation were also quantified to explore the microbial mechanisms of the TAP influence. Production of N 2 were observed to be inhibited by TAP treatment, which implied the inhibition effect of TAP on nitrate reduction processes. As intermediate products of nitrogen transformation processes, nitrite and N 2 O were observed to accumulate during the incubation. Different TAP inhibition effects on related functional genes may be the microbial mechanism for the changes of nutrient fluxes, N 2 fluxes and N 2 O release rates. These results indicate that the antibiotics residues in estuarine and coastal ecosystems may contribute to nitrate retention and N 2 O release, which could be a major factor responsible for eutrophication and greenhouse effects. - Highlights: • Production of N 2 are inhibited by the TAP treatment. • Accumulation of nitrite and N 2 O is stimulated by TAP treatment. • Different TAP effects on functional genes may be the microbial mechanism. - TAP inhibits the production of N 2 and stimulates the accumulation of nitrite and N 2 O due to its different inhibition effects on functional genes.

  2. Effects of mine drainage on the River Hayle, Cornwall. Factors affecting concentrations of copper, zinc, and iron in water, sediments and dominant invertebrate fauna

    Energy Technology Data Exchange (ETDEWEB)

    Brown, B.E.

    1977-02-15

    Concentrations of copper, zinc and iron were measured in waters, sediments and invertebrates collected from the River Hayle. In river water at least 70% of copper and iron was associated with the ''particulate'' fraction whereas 80% of zinc was in the ''soluble'' form. Although total concentrations of zinc in water exceeded those of copper approximately ten fold, copper predominated over zinc in the sediments by a factor of approximately three. Iron was the most abundant metal recorded in both water and sediments. Seasonal differences in ''total'' metal content of waters suggested that concentrations of copper, zinc and iron increased during periods of high flow and decreased during lower flows. Copper concentrations in the sediment, unlike zinc and iron, showed markedly higher values during the summer sampling period when flows were minimal. In the ''free-living'' Trichoptera larvae, concentrations of copper and zinc in the tissue appeared to follow copper and zinc levels in the water. Similar relationships in Odonata and Plecoptera larvae were not obtained. Factors affecting animal/metal relationships are discussed with particular reference to adaptation shown by organisms exposed to high concentrations of heavy metals in their environment.

  3. Radioactivity and Natural Radio nuclides Distribution in River Water, Coastal Water, Sediment and Eichornia Crassipes (Mart) Sloms and Their Accumulation Factor at Surabaya Area

    International Nuclear Information System (INIS)

    Agus Taftazani; Sumining; Muzakky

    2002-01-01

    Distribution of radioactivity and natural radionuclide in water, sediment and eichornia crassipes (mart) sloms from Surabaya river and coastal area have been evaluated. Five sampling locations were selected to represent fresh water and coastal water environment. The samples consist of water (fresh and coastal), bottom surface sediment and eichornia crassipes (mart) sloms The result showed that the gross-β activity from water environment were lower than the threshold value of Environmental Minister Act. Kep.02/MENKLH/I/1988 (1000 mBq/L) and indicated that β-radioecological quality of water were still good. But the activity of the gross-α of water environment were higher than the threshold value of Environmental Minister Act. Kep.02/MENKLH/I/1988 (100 mBq/L). The eichornia crassipes (mart) sloms (gross) activity were higher than water and sediment activities and indicated that transfer of radionuclides from water to sediment and organism can be detected in water environment. Two natural radionuclides can be identified by γ-Spectrometric technique, they were K-40 and TI-208. Generally the distribution factor F D were smaller than bioaccumulation factor F B . (author)

  4. Radioactivity and natural radionuclides distribution in river water, coastal water, sediment and Eichornia Crassipes (Mart) solms and their accumulation factor at Surabaya area

    International Nuclear Information System (INIS)

    Agus Taftazani; Sumining; Muzakky

    2002-01-01

    Distributions of radioactivity and natural radionuclides in water, sediment and eichornia crassipes (mart) solms from Surabaya River and coastal area have been evaluated. Five sampling locations were selected to represent fresh water and coastal water environment. The samples consist of water (fresh & coastal), bottom surface sediment and eichornia crassipes (mart) solms. The result showed that the gross-β activity from water environment were lower than the threshold value of Environmental Minister Act. Kep.02/MENKLH/I/1988 (1000 mBq/L) and indicated that β-radio ecological quality of water were still good. But the activity of the gross-α of water environment were higher than the threshold value of Environmental Minister Act. Kep.02/MENKLH/I/1988 (100 mBq/L). The eichornia crassipes (mart) solms (gross) activity were higher than water and sediment activities and indicated that transfer of radio nuclides from water to sediment and organism can be detected in water environment. Two natural radionuclide can be identified by γ-Spectrometric technique, they were K"4"0 and Tl"2"0"8. Generally the distribution factors F_D were smaller than bioaccumulation factor F_B. (author)

  5. Influence of morphodynamic variability over seasonal beach sediments and its probable effect on coastal development

    Digital Repository Service at National Institute of Oceanography (India)

    Gujar, A.R.; Ganesan, P.; Iyer, S.D.; Gaonkar, S.S.; Ambre, N.V.; Loveson, V.J.; Mislankar, P.G.

    could be finalised after a proper assessment of cost to benefit ratio which may be in accordance with the facilities and developments that would be created along the coastal strip. However, a reinforced concrete wall along with locally available rocks... energy and reflect the waves back to the sea. For the areas that are less vulnerable to erosion i.e. Bagwadi, a low cost bulkhead or sand bags or geotextiles could be used to minimise beach erosion. Geotextiles covering completely the slope area...

  6. Microalgal Photosynthesis and Spectral Scalar Irradiance in Coastal Marine-Sediments of Limfjorden, Denmark

    DEFF Research Database (Denmark)

    LASSEN, C.; PLOUG, H.; JØRGENSEN, BB

    1992-01-01

    (bacteriochlorophyll a). Infrared scalar irradiance reached 200% of incident light intensity at 0.0-0.3-mm depth and IR penetration was independent of the development of a cyanobacterial surface film. At high incident light intensity, 740 muEinst m-2 s-1, the photosynthetic efficiency at 1.0-mm depth was 10-fold...... higher than in the uppermost 0.0-0.6 mm of the sediment. The lower boundary of the euphotic zone (detectable gross photosynthesis) was at a mean light level of greater-than-or-equal-to 7.5 muEinst m-2 s-1.......Scalar irradiance and oxygenic photosynthesis were measured simultaneously at 100-mum spatial resolution by a fiber-optic scalar irradiance microsensor and an oxygen microelectrode spaced 120 mum apart. Marine microbial mats on sandy sediments along the coast of Limfjorden, Denmark, were dominated...

  7. Trace metals in antifouling paint particles and their heterogeneous contamination of coastal sediments

    International Nuclear Information System (INIS)

    Singh, Nimisha; Turner, Andrew

    2009-01-01

    Antifouling paint residues collected from the hard-standings of a marine leisure boat facility have been chemically characterised. Scanning electron microscopy revealed distinct layers, many containing oxidic particles of Cu and Zn. Quantitative analysis indicated concentrations of Cu and Zn averaging about 300 and 100 mg g -1 , respectively, and small proportions of these metals ( -1 , respectively. Estuarine sediment collected near a boatyard contained concentrations of Cu and Zn an order of magnitude greater than respective concentrations in 'background' sediment, and mass balance calculations suggested that the former sample was contaminated by about 1% by weight of paint particles. Clearly, antifouling residues represent a highly significant, heterogeneous source of metallic contamination in the marine environment where boating activities occur.

  8. Structure of hydrocarbonoclastic nitrate-reducing bacterial communities in bioturbated coastal marine sediments.

    Science.gov (United States)

    Stauffert, Magalie; Cravo-Laureau, Cristiana; Duran, Robert

    2014-09-01

    The organisation of denitrifying microorganisms in oil-polluted bioturbated sediments was investigated in mesocosms under conditions as closer as possible to that observed in the environment. Molecular and culture-dependent approaches revealed that denitrifying Gammaproteobacteria were abundant in oil-polluted and bioturbated sediments suggesting that they may play a key role in hydrocarbon degradation in the environment. T-RFLP and gene libraries analyses targeting nirS gene showed that denitrifying microbial communities structure was slightly affected by either the addition of Hediste diversicolor or crude oil revealing the metabolic versatility of denitrifying microorganisms. From oil-polluted sediments, distinct denitrifying hydrocarbonoclastic bacterial consortia were obtained by enrichment cultures on high molecular weight polyaromatic hydrocarbons (PAHs) (dibenzothiophene, fluoranthene, pyrene and chrysene) under nitrate-reducing conditions. Interestingly, molecular characterisation of the consortia showed that the denitrifying communities obtained from oiled microcosms with addition of H. diversicolor were different to that observed without H. diversicolor addition, especially with fluoranthene and chrysene revealing the bacterial diversity involved in the degradation of these PAHs. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  9. Methods for the shipboard determination of dissolved iron and manganese in samples of sediment interstitial water

    International Nuclear Information System (INIS)

    Hydes, D.J.; Chapman, E.

    1986-01-01

    Iron is extremely unstable in the presence of oxygen. A working atmosphere containing less than 0.2% oxygen is required if iron losses are not to be significant. Iron can be determined with a single addition of reagent, either manually or by a continuous flow procedure using ferrozine. Using a continuous flow procedure with a 5 cm colorimeter cell the method is linear up to 40 μM Fe and the precision is 2%. Manganese can similarly be determined with a single reagent addition using formaldoxime. For the continuous flow procedure with a 5 cm colorimeter cell the method is linear up to 60 μM Mn and the precision is 1%; however, under these conditions a solution containing 100 μm of iron produces an interference equivalent to 4.7 μM of manganese. A two-reagent procedure was developed using EDTA to suppress the iron interference. Using a 5% EDTA solution interference from a solution containing 100 μM of iron was undetectable. (author)

  10. Screening-level ecological and human health risk assessment of polycyclic aromatic hydrocarbons in stormwater detention pond sediments of Coastal South Carolina, USA

    Energy Technology Data Exchange (ETDEWEB)

    Weinstein, John E., E-mail: john.weinstein@citadel.edu [Department of Biology, The Citadel, Charleston, SC (United States); Crawford, Kevin D. [Department of Chemistry, University of Wisconsin-Oshkosh, Oshkosh, WI (United States); Garner, Thomas R. [Institute of Environmental Toxicology, Clemson University, Pendleton, SC (United States); Flemming, Alan J. [South Carolina Department of Health and Environmental Control, Charleston, SC (United States)

    2010-06-15

    Screening-level ecological and human health assessments were performed for polycyclic aromatic hydrocarbon (PAH) contamination in the sediments of 19 stormwater detention ponds located in coastal South Carolina. For ecological screening benchmarks, we used threshold and probable effect concentrations (TEC and PEC) derived from consensus-based sediment quality guidelines for individual PAH analytes and equilibrium partitioning sediment benchmarks-toxic units ({Sigma}ESB-TU) derived for PAH mixtures. For human health benchmarks, we used preliminary remediation goals (PRGs). Sediments of five stormwater ponds (four commercial ponds and one residential pond with a large drainage area) exceeded PEC values for several PAH analytes and the {Sigma}ESB-TU safe value of 1 for PAH mixtures. These same five stormwater ponds also exceeded the PRG values for five carcinogenic PAH analytes. These results suggest that the PAH levels in sediments from certain commercial and residential ponds have the potential to pose moderate to high risks for adverse, chronic effects to benthic organisms in situ and an increased risk of cancer to humans ex situ following excavation and on-site disposal. We recommend that sediment from these stormwater ponds be tested prior to excavation to determine the appropriate method of disposal. We also recommend that regulatory agencies enforce guidelines for periodic sediment removal as this should reduce both in situ and ex situ risks resulting from sediment PAH exposure.

  11. Screening-level ecological and human health risk assessment of polycyclic aromatic hydrocarbons in stormwater detention pond sediments of Coastal South Carolina, USA

    International Nuclear Information System (INIS)

    Weinstein, John E.; Crawford, Kevin D.; Garner, Thomas R.; Flemming, Alan J.

    2010-01-01

    Screening-level ecological and human health assessments were performed for polycyclic aromatic hydrocarbon (PAH) contamination in the sediments of 19 stormwater detention ponds located in coastal South Carolina. For ecological screening benchmarks, we used threshold and probable effect concentrations (TEC and PEC) derived from consensus-based sediment quality guidelines for individual PAH analytes and equilibrium partitioning sediment benchmarks-toxic units (ΣESB-TU) derived for PAH mixtures. For human health benchmarks, we used preliminary remediation goals (PRGs). Sediments of five stormwater ponds (four commercial ponds and one residential pond with a large drainage area) exceeded PEC values for several PAH analytes and the ΣESB-TU safe value of 1 for PAH mixtures. These same five stormwater ponds also exceeded the PRG values for five carcinogenic PAH analytes. These results suggest that the PAH levels in sediments from certain commercial and residential ponds have the potential to pose moderate to high risks for adverse, chronic effects to benthic organisms in situ and an increased risk of cancer to humans ex situ following excavation and on-site disposal. We recommend that sediment from these stormwater ponds be tested prior to excavation to determine the appropriate method of disposal. We also recommend that regulatory agencies enforce guidelines for periodic sediment removal as this should reduce both in situ and ex situ risks resulting from sediment PAH exposure.

  12. Sedimentation and remobilization of radiocesium in the coastal area of Ibaraki, 70 km south of the Fukushima Dai-ichi Nuclear Power Plant.

    Science.gov (United States)

    Otosaka, Shigeyoshi; Kobayashi, Takuya

    2013-07-01

    Sedimentation and remobilization processes of radiocesium were investigated from time-series observations at nine stations in the coastal area of Ibaraki, 70-110 km south of the Fukushima Dai-ichi Nuclear Power Plant (1FNPP). Sediment samples were collected four times between June 2011 and January 2012, and concentrations of radiocesium as well as sediment properties such as grain size and elemental compositions were analyzed. Cumulative inventory of (137)Cs in sediment (0-10 cm) ranged between 4 × 10(3) and 3 × 10(4) Bq/m(2) as of January 2012. This amount was generally higher at stations nearer 1FNPP and has remained at the same level since August 2011. From these results, it can be inferred that dissolved radiocesium advected southward from the region adjacent to the 1FNPP and was deposited to the sediment of the study area in the early stage after the accident. The incorporation of radiocesium into sediments was almost irreversible, and higher concentrations of (137)Cs were obtained from the finer-grained fraction of sediments. In the northern offshore stations, resuspension of the fine-grained sediments formed a high-turbidity layer 10-20 m above the seabed. These results indicate that radiocesium-enriched fine particles were transported from the coast to offshore regions through the bottom high-turbidity layer.

  13. Sedimentation

    Science.gov (United States)

    Cliff R. Hupp; Michael R. Schening

    2000-01-01

    Sedimentation is arguably the most important water-quality concern in the United States. Sediment trapping is cited frequently as a major function of riverine-forested wetlands, yet little is known about sedimcntation rates at the landscape scale in relation to site parameters, including woody vegetation type, elevation, velocity, and hydraulic connection to the river...

  14. Microbial-meiofaunal interrelationships in coastal sediments of the Red Sea.

    Science.gov (United States)

    El-Serehy, Hamed A; Al-Rasheid, Khaled A; Al-Misned, Fahad A; Al-Talasat, Abdul Allah R; Gewik, Mohamed M

    2016-05-01

    Population density and biomass of bacteria and meiofauna were investigated seasonally in the sediments of the north-western bank of Red Sea. Samples of sediments were collected seasonally from three different stations to determine microphytobenthic biomass (chlorophyll a), protein, lipid, carbohydrate, and total organic matter concentrations. These investigations revealed that microbial components tended to increase their dominancy, whereas sensitive meiofauna were extremely reduced during the entire study period. Thus a very low density of the total meiofauna (with an annual average of 109 ± 26 ind./10 cm(2)) was recorded whilst the benthic microbial population densities exhibited higher values (ranging from 0.31 ± 0.02 × 10(8) to 43.67 ± 18.62 × 10(8)/g dry sediment). These changes in the relative importance analysis of benthic microbial components versus meiofaunal ones seem to be based on the impact of organic matter accumulation on the function and structure of these benthic communities. Proteins, lipids and carbohydrates showed very low concentration values, and the organic matter mostly consisted of carbohydrates, reflecting lower nutritional values for benthic fauna in general and meiofauna in particular. The distribution of microbial and meiofaunal communities seems to be dependent on the quality of the organic matter rather than on its quantity. Total organic matter concentrations varied between 5.8 and 7.6 mg/g, with organic carbon accounting for only 32% of the total organic matter. Chlorophyll a attained very low values, fluctuating between 0.11 and 0.56 μg/g, indicating the oligotrophy of the studied area. The very low concentration of chlorophyll a in the Red Sea sediment suggests that the sedimentary organic matter, heterotrophic bacteria and/or protozoa constitute an alternative resource that is consumed by meiofauna when algae are less abundant. Protozoa, therefore, represent the "missing link in bacteria-meiofauna interaction

  15. Assessment of sediment metal contamination in the Mar Menor coastal lagoon (SE Spain: Metal distribution, toxicity, bioaccumulation and benthic community structure

    Directory of Open Access Journals (Sweden)

    2005-01-01

    Full Text Available The Mar Menor coastal lagoon is one of the largest of the Mediterranean Sea. Ancient mining activities in the mountains near its southern basin have resulted in metal contamination in the sediment. The metal bioavailability of these sediments was determined through laboratory toxicity bioassays using three Mediterranean sea urchin species and two amphipod species, and by means of field bioaccumulation measurements involving the seagrass Cymodocea nodosa. The effect of sediment metal contamination on benthic communities was assessed through benthic infaunal analyses, applying classical descriptive parameters and multivariate techniques. The sediments affected by the mining activities presented high levels of toxicity and metals were also accumulated in the seagrass tissues, pointing to metal bioavailability. Although the classical benthic indices were not clear indicators of disturbance, the multivariate techniques applied provided more consistent conclusions.

  16. The Analysis of Heavy Metal in Sea Water and Sediment from MuriaPeninsula Coastal Area by NAA Method

    International Nuclear Information System (INIS)

    TS, Susanna; Sukirno

    2000-01-01

    The analysis of heavy metal in sea water and sediment taken from Muriacoastal sites in Central Java has been carried out. This research aimed tosupport the EMSB and Ocean Radioecology programme. The sea water sample wasdried with electrical brazier till crystal form, and balanced. Whereas thesediment sample was cleaned, dried at opened air, powdered, screened andhomogenized. Irradiation of samples and standard were done for twelve hoursusing Lazy Susan facility, Kartini reactor with neutron flux of 5.85 x10 10 .n.cm -2 .s -1 . Comparative method of measurements was used foravoiding the effects of neutron flux parameters on the results. Using gammaspectrometer equipment with a Ge(Li) detector and multi channel analyzer with4096 channels, 7 elements were concealed in the sea water; i.e. Fe, Se, Co,Cr, Ce, Sm and Sc were detected, whereas in the sediment sample concealed 10elements were detected, i.e. Fe, Se, Co, Cr, As, Ce, Sm, Th, U and Sc. It wasfound that the elements concentrations in the sediment sample from Muria baywere higher than those elements concentrations in the sea water sample. Theconcentrations of Fe, Se, Co, Cr, Ce, Sm and Sc in the sediment sample fromMuria peninsula coastal area were Fe = 19.923 ± 2.162%, Se = 1.320 ±0.141 ppm, Co = 0.570 ± 0.066 ppm, Cr = 0.410 ± 0.031 ppm, As = 0.500± 0.043 ppm, Ce = 0.774 ± 0.210 ppm, Sm = 1.860 ± 0.210 ppm, Th1.930 ± 0.173 ppm, U = 0.663 ± 0.027 ppm, dan Sc = 0.190 ± 0.003ppm, whereas the concentration elements in the sea water sample were Fe 0.112± 0.007%, Se = 0.305 ± 0.008 ppm, Co = 0.047 ± 0.002 ppm, Cr 0.023± 0.001 ppm, Ce = 0.022 ± 0.001 ppm, Sm = 14 ± 0.8 ppb dan Sc = 2.4ppb, respectively. (author)

  17. REDUCTIVE DEHALOGENATION OF HALOMETHANES IN IRON- AND SULFATE-REDUCING SEDIMENTS. 1. REACTIVITY PATTERN ANALYSIS

    Science.gov (United States)

    The incorporation of reductive transformations into environmental fate models requires the characterization of natural reductants in well-characterized sediments and aquifer materials. For this purpose, reactivity patterns (i.e., the range and relative order of reactivity) for a...

  18. Occurrence and distribution of selected heavy metals in the surface sediments of South Brittany coastal waters: An assessment using pollution indicators

    Science.gov (United States)

    Ong, M. C.; Menier, D.; Noor Azhar, M. S.; Dupont, V.; Révillon, S.

    2012-04-01

    In order to avoid the pollution of heavy metals in South Brittany water, it is necessary to establish the data and understand the mechanisms influencing the distribution of heavy metals of the area. One of the aims of this work was to assess heavy metals contamination in Gulf of Morbihan and Quiberon Bay. Another aim was to use interpolation surfaces per metals to assess the contamination separately per metal. A total of 196 bottom sediment samples were collected from the coastal waters in order to determine the spatial concentration of Cr, Mn, Co, Cu, Zn, Cd and Pb by Inductively Coupled Plasma Mass Spectrometry (ICPMS) after acid digestion. The average heavy metal concentrations are ranked as follows: Mn>Zn>Cr>Pb>Cu>Cu>Cd. In the gulf, metal enrichments observed compared to the bay environment may due river run-off from three major river (Auray, Le Marle and Novalo rivers) which carried municipal waste and maritime activities along the coastal area within the gulf. Beside those factors, the natural factors such as the sheltered basin morphology itself, fine sediment and low hydrodynamic regime which favour the in situ accumulation of pollutants. The level of pollution levels attributed to heavy metals was evaluated using several pollution indicators in order to determine anthropogenically derived sediment contamination. Comparison to sediment quality guidelines (SQGs), enrichment factors (EFs), index of geoaccumulation (Igeo) and contamination factors (CF) based on reference element and background value to compensate for the influence of the natural variability in sediment mineralogy and to assess whether the concentration observed in surface sediment represent background and contaminated levels and visualize using ArcGIS software. These analyses validated that the bottom sediment only enriched in Pb and the other metals in most sample are not due to artificial contamination. Overall, geochemistry of the samples show the effect of both natural and anthropogenic

  19. Hundred years of environmental change and phytoplankton ecophysiological variability archived in coastal sediments.

    Directory of Open Access Journals (Sweden)

    Sofia Ribeiro

    Full Text Available Marine protist species have been used for several decades as environmental indicators under the assumption that their ecological requirements have remained more or less stable through time. However, a growing body of evidence suggests that marine protists, including several phytoplankton species, are in fact highly diverse and may quickly respond to changes in the environment. Predicting how future climate will impact phytoplankton populations is important, but this task has been challenged by a lack of time-series of ecophysiological parameters at time-scales relevant for climate studies (i.e. at least decadal. Here, we report on ecophysiological variability in a marine dinoflagellate over a 100-year period of well-documented environmental change, by using the sedimentary archive of living cysts from a Scandinavian fjord (Koljö Fjord, Sweden. During the past century, Koljö Fjord has experienced important changes in salinity linked to the North Atlantic Oscillation (NAO. We revived resting cysts of Pentapharsodinium dalei preserved in the fjord sediments and determined growth rates for 18 strains obtained from 3 sediment core layers at salinity 15 and 30, which represent extreme sea-surface conditions during periods of predominantly negative and positive NAO phases, respectively. Upper pH tolerance limits for growth were also tested. In general, P. dalei grew at a higher rate in salinity 30 than 15 for all layers, but there were significant differences among strains. When accounting for inter-strain variability, cyst age had no effect on growth performance or upper pH tolerance limits for this species, indicating a stable growth response over the 100-year period in spite of environmental fluctuations. Our findings give some support for the use of morphospecies in environmental studies, particularly at decadal to century scales. Furthermore, the high intra-specific variability found down to sediment layers dated as ca. 50 years-old indicates

  20. Processes influencing the transport and fate of contaminated sediments in the coastal ocean: Boston Harbor and Massachusetts Bay

    Science.gov (United States)

    Alexander, P. Soupy; Baldwin, Sandra M.; Blackwood, Dann S.; Borden, Jonathan; Casso, Michael A.; Crusius, John; Goudreau, Joanne; Kalnejais, Linda H.; Lamothe, Paul J.; Martin, William R.; Martini, Marinna A.; Rendigs, Richard R.; Sayles, Frederick L.; Signell, Richard P.; Valentine, Page C.; Warner, John C.; Bothner, Michael H.; Butman, Bradford

    2007-01-01

    Most of the major urban centers of the United States including Boston, New York, Washington, Chicago, New Orleans, Miami, Los Angeles, San Francisco, and Seattle—are on a coast (fig. 1.1). All of these cities discharge treated sewage effluent into adjacent waters. In 2000, 74 percent of the U.S. population lived within 200 kilometers (km) of the coast. Between 1980 and 2002, the population density in coastal communities increased approximately 4.5 times faster than in noncoastal areas of the U.S. (Perkins, 2004). More people generate larger volumes of wastes, increase the demands on wastewater treatment, expand the area of impervious land surfaces, and use more vehicles that contribute contaminants to street runoff. According to the National Coastal Condition Report II (U.S. Environmental Protection Agency, 2005a), on the basis of coastal habitat, water and sediment quality, benthic index, and fish tissue, the overall national coastal condition is only poor to fair and the overall coastal condition in the highly populated Northeast is poor. Scientific information helps managers to prioritize and regulate coastal-ocean uses that include recreation, commercial fishing, transportation, waste disposal, and critical habitat for marine organisms. These uses are often in conflict with each other and with environmental concerns. Developing a strategy for managing competing uses while maintaining sustainability of coastal resources requires scientific understanding of how the coastal ocean system behaves and how it responds to anthropogenic influences. This report provides a summary of a multidisciplinary research program designed to improve our understanding of the transport and fate of contaminants in Massachusetts coastal waters. Massachusetts Bay and Boston Harbor have been a focus of U.S. Geological Survey (USGS) research because they provide a diverse geographic setting for developing a scientific understanding of the geology, geochemistry, and oceanography of

  1. Ice sheets as a significant source of highly reactive nanoparticulate iron to the oceans.

    Science.gov (United States)

    Hawkings, Jon R; Wadham, Jemma L; Tranter, Martyn; Raiswell, Rob; Benning, Liane G; Statham, Peter J; Tedstone, Andrew; Nienow, Peter; Lee, Katherine; Telling, Jon

    2014-05-21

    The Greenland and Antarctic Ice Sheets cover ~ 10% of global land surface, but are rarely considered as active components of the global iron cycle. The ocean waters around both ice sheets harbour highly productive coastal ecosystems, many of which are iron limited. Measurements of iron concentrations in subglacial runoff from a large Greenland Ice Sheet catchment reveal the potential for globally significant export of labile iron fractions to the near-coastal euphotic zone. We estimate that the flux of bioavailable iron associated with glacial runoff is 0.40-2.54 Tg per year in Greenland and 0.06-0.17 Tg per year in Antarctica. Iron fluxes are dominated by a highly reactive and potentially bioavailable nanoparticulate suspended sediment fraction, similar to that identified in Antarctic icebergs. Estimates of labile iron fluxes in meltwater are comparable with aeolian dust fluxes to the oceans surrounding Greenland and Antarctica, and are similarly expected to increase in a warming climate with enhanced melting.

  2. Palynomorphs in Holocene sediments from a paleolagoon in the coastal plain of extreme southern Brazil

    OpenAIRE

    Ebráilon Masetto; Maria Luisa Lorscheitter

    2014-01-01

    This paper presents the results of a qualitative palynological analysis of a 140 cm-thick section of Holocene sediments from a paleolagoon, representing the last 2600 years, taken from an outcrop at Hermenegildo Beach (33º42'S; 53º18'W), located in the municipality of Santa Vitória do Palmar, in the state of Rio Grande do Sul, Brazil. Samples were treated with hydrochloric acid, hydrofluoric acid and potassium hydroxide, after which they were subjected to acetolysis and mounted on glycerin-co...

  3. Iron Mineralogy and Speciation in Clay-Sized Fractions of Chinese Desert Sediments

    Science.gov (United States)

    Lu, Wanyi; Zhao, Wancang; Balsam, William; Lu, Huayu; Liu, Pan; Lu, Zunli; Ji, Junfeng

    2017-12-01

    Iron released from Asian desert dust may be an important source of bioavailable iron for the North Pacific Ocean and thereby may stimulate primary productivity. However, the Fe species of the fine dusts from this source region are poorly characterized. Here we investigate iron species and mineralogy in the clay-sized fractions (iron phases (ferrihydrite and lepidocrocite) and reducible iron oxides (dominated by goethite) are 0.81 wt % and 2.39 wt %, respectively, and Fe dissolved from phyllosilicates extracted by boiling HCl (dominated by chlorite) is 3.15 wt %. Dusts originating from deserts in northwestern China, particularly the Taklimakan desert, are relatively enriched in easily reducible Fe phases, probably due to abundant Fe contained in fresh weathering products resulting from the rapid erosion associated with active uplift of mountains to the west. Data about Fe speciation and mineralogy in Asian dust sources will be useful for improving the quantification of soluble Fe supplied to the oceans, especially in dust models.

  4. Enhanced ocean carbon storage from anaerobic alkalinity generation in coastal sediments

    Directory of Open Access Journals (Sweden)

    H. Thomas

    2009-02-01

    Full Text Available The coastal ocean is a crucial link between land, the open ocean and the atmosphere. The shallowness of the water column permits close interactions between the sedimentary, aquatic and atmospheric compartments, which otherwise are decoupled at long time scales (≅ 1000 yr in the open oceans. Despite the prominent role of the coastal oceans in absorbing atmospheric CO2 and transferring it into the deep oceans via the continental shelf pump, the underlying mechanisms remain only partly understood. Evaluating observations from the North Sea, a NW European shelf sea, we provide evidence that anaerobic degradation of organic matter, fuelled from land and ocean, generates total alkalinity (AT and increases the CO2 buffer capacity of seawater. At both the basin wide and annual scales anaerobic AT generation in the North Sea's tidal mud flat area irreversibly facilitates 7–10%, or taking into consideration benthic denitrification in the North Sea, 20–25% of the North Sea's overall CO2 uptake. At the global scale, anaerobic AT generation could be accountable for as much as 60% of the uptake of CO2 in shelf and marginal seas, making this process, the anaerobic pump, a key player in the biological carbon pump. Under future high CO2 conditions oceanic CO2 storage via the anaerobic pump may even gain further relevance because of stimulated ocean productivity.

  5. Increasing coastal slump activity impacts the release of sediment and organic carbon into the Arctic Ocean

    Directory of Open Access Journals (Sweden)

    J. L. Ramage

    2018-03-01

    Full Text Available Retrogressive thaw slumps (RTSs are among the most active thermokarst landforms in the Arctic and deliver a large amount of material to the Arctic Ocean. However, their contribution to the organic carbon (OC budget is unknown. We provide the first estimate of the contribution of RTSs to the nearshore OC budget of the Yukon Coast, Canada, and describe the evolution of coastal RTSs between 1952 and 2011 in this area. We (1 describe the evolution of RTSs between 1952 and 2011; (2 calculate the volume of eroded material and stocks of OC mobilized through slumping, including soil organic carbon (SOC and dissolved organic carbon (DOC; and (3 estimate the OC fluxes mobilized through slumping between 1972 and 2011. We identified RTSs using high-resolution satellite imagery from 2011 and geocoded aerial photographs from 1952 and 1972. To estimate the volume of eroded material, we applied spline interpolation on an airborne lidar dataset acquired in July 2013. We inferred the stocks of mobilized SOC and DOC from existing related literature. Our results show a 73 % increase in the number of RTSs and 14 % areal expansion between 1952 and 2011. In the study area, RTSs displaced at least 16.6×106 m3 of material, 53 % of which was ice, and mobilized 145.9×106 kg of OC. Between 1972 and 2011, 49 RTSs displaced 8.6×103 m3 yr−1 of material, adding 0.6 % to the OC flux released by coastal retreat along the Yukon Coast. Our results show that the contribution of RTSs to the nearshore OC budget is non-negligible and should be included when estimating the quantity of OC released from the Arctic coast to the ocean.

  6. Caracterização de óxidos de ferro de solos do ambiente tabuleiros costeiros Characterizing iron oxides from coastal and central plain soils

    Directory of Open Access Journals (Sweden)

    Marcelo Metri Correa

    2008-06-01

    apresentou correlação com algumas propriedades cristalográficas das goethitas dos solos estudados, mostrando-se ser uma técnica promissora para o estudo dos óxidos de ferro.There have been several papers in the literature studying the genesis and consequences of particles cohesion in Argisols (Ultisols and Latosols (Oxisols from the Brazilian Inner and Coastal Plains. Just a few, however, provide insights into the clay fraction mineralogy, specially, the iron oxides complete characterization. The objective of this study was to investigate the chemical and crystallographic characteristics of iron oxides in red and yellow soils derived from the sediments of the Barreiras Formation or Pre-Cambrian rocks in the region of the coastal and central plateaus of several Brazilian states. The following research procedures were used: X-ray diffraction analyses in iron oxide-concentrated samples; successive extractions with CBD, and ammonium oxalate extraction in clay samples; spectral characterization by DRS; estimation of the crystallographic properties of goethite; quantification of isomorphic substitution of Fe for Al; and electronic transmission microscopy. According to the results, the following conclusions were drawn: (a goethite was the predominant iron oxide in all soils, even in those with 2.5YR hues, of which the hematite value was below 2.5 dag kg-1 clay; (b the values of the isomorphic Fe substitution by Al were 3 to 6 times higher for goethites than for hematites. These values did not agree with those estimated by mathematical models proposed in the scientific literature, which indicates the need for further studies of the relationships between crystallographic parameters of natural goethites and their chemical properties; (c the results obtained by X ray diffractometry and chemical dissolution analysis revealed that the goethites in the soils differ from those cited, to date, in the literature; (d the position of the bands obtained in the spectra of the diffuse

  7. Biogeochemistry of sulfur and iron in Thioploca-colonized surface sediments in the upwelling area off central chile

    Science.gov (United States)

    Zopfi, Jakob; Böttcher, Michael E.; Jørgensen, Bo Barker

    2008-02-01

    The biogeochemistry of sedimentary sulfur was investigated on the continental shelf off central Chile at water depths between 24 and 88 m under partial influence of an oxygen minimum zone. Dissolved and solid iron and sulfur species, including the sulfur intermediates sulfite, thiosulfate, and elemental sulfur, were analyzed at high resolution in the top 20 cm. All stations were characterized by high rates of sulfate reduction, but only the sediments within the Bay of Concepción contained dissolved sulfide. Due to advection and/or in-situ reoxidation of sulfide, dissolved sulfate was close to bottom water values. Whereas the concentrations of sulfite and thiosulfate were mostly in the submicromolar range, elemental sulfur was by far the dominant sulfur intermediate. Although the large nitrate- and sulfur-storing bacteria Thioploca were abundant, the major part of S 0 was located extracellularly. The distribution of sulfur species and dissolved iron suggests the reaction of sulfide with FeOOH as an important pathway for sulfide oxidation and sulfur intermediate formation. This is in agreement with the sulfur isotope composition of co-existing elemental sulfur and iron monosulfides. In the Bay of Concepción, sulfur isotope data suggest that pyrite formation proceeds via the reaction of FeS with polysulfides or H 2S. At the shelf stations, on the other hand, pyrite was significantly depleted in 34S relative to its potential precursors FeS and S 0. Isotope mass balance considerations suggest further that pyritization at depth includes light sulfide, potentially originating from bacterial sulfur disproportionation. The δ 34S-values of pyrite down to -38‰ vs. V-CDT are among the lightest found in organic-rich marine sediments. Seasonal variations in the sulfur isotope composition of dissolved sulfate indicated a dynamic non-steady-state sulfur cycle in the surface sediments. The 18O content of porewater sulfate increased with depth at all sites compared to the

  8. Hydrocarbons in surface sediments from the Sfax coastal zone, (Tunisia) Mediterranean Sea.

    Science.gov (United States)

    Zaghden, Hatem; Kallel, Monem; Louati, Afifa; Elleuch, Boubaker; Oudot, Jean; Saliot, Alain

    2005-11-01

    The Semi-enclosed Mediterranean Sea records various signals of high anthropic pressures from surrounding countries and the industrialized European countries. This is particularly true for oil pollution. Although accounting for 1% of the world's ocean surface, it receives about 25% of the petroleum inputs to the ocean. To achieve a global budget we need to collect information from different parts of the Mediterranean. Particularly, we focus in this paper on the Southern Mediterranean, where data are presently very scarce. In this context, the University of Sfax has undertaken an estimation of hydrocarbon pollution along the coasts of Sfax and Gabès Gulf. Non-aromatic hydrocarbons were analysed in 8 surface sediments by FT/IR and GC/MS. Non-aromatic hydrocarbon concentrations vary in the range 310-1406 microg g(-1) sediments dry weight, which is high, compared to other Mediterranean sites. GC/MS data indicate a large group of unresolved compounds suggesting a petroleum contamination, confirmed by the identification of hopanes with predominant C29 and C30alpha,beta compounds and steranes with predominance of C27 over C28) and C29 compounds.

  9. Environmental impact of the Midia Port - Black Sea (Romania, on the coastal sediment quality

    Directory of Open Access Journals (Sweden)

    Catianis Irina

    2016-03-01

    Full Text Available The aim of the study was to evaluate the impact of potential pollution sources, mainly from the upstream anthropogenic sources and port-related activities. The in-vestigated area covered a wide range of anthropogenic im-pacts (e.g., industrial wastes, storm water runoff, acciden-tal oil spills, intentional discharges and shipping activities. The quality of water and Sediments was assessed us-ing Standard methods, as physical-chemical parameters, chemistry and biology (microbiology, ecotoxicology aim-ing to figure the level of pollution and the effect of port-related activities. Seawater quality results agreed generally with environmental Standards. Though, in some samples the concentrations of sulphates (mg/1 and heavy metals (μg/1, as B, As and Se exceeded the recommended lim-its, without posing a serious environmental concern. Most of the surface sediment samples contain critical levels of hydrocarbons (C>12, (mg/kg, polycyclic aromatic hydrocarbons (ng/g and polychlorobiphenyls (ng/g. For some heavy metals (mg/kg, exchangeable concentrations were found to be very close or above the regulations. The signifi-cance of this study is incontestable taking into account the lack of previous relevant historical data of this area. In this sense, it was possible to indicate, in general, good environmental conditions, despite the industrial and concentrated local port-related activities in the investigated area.

  10. Change in coastal sedimentation conditions due to positive shore displacement in Oeregrundsgrepen

    International Nuclear Information System (INIS)

    Brydsten, Lars

    1999-12-01

    This report is a part the SKB project 'SAFE' (Safety Assessment of the Final Repository of Radioactive Operational Waste). The aim of project SAFE is to update the previous safety analysis of SFR-1. SFR-1 is a low and intermediate level radioactive waste disposal facility, which is situated in bedrock beneath the Baltic Sea, 1 km off the coast near the Forsmark Nuclear Power Plant. At a possible discharge of radionuclides from SFR-1 today, ground water currents will presumably transport the radionuclides to the sea bottom. Many radionuclides are able to absorb on to fine particles, and it is likely that the radionuclides would adsorb on to particles in the sediment or particles suspended in the seawater. The adsorption is strong, and therefore the dynamics of the radionuclides are governed by the dynamics of the fine particles. A mathematical model has been developed to simulate the resuspension of fine particles caused by wave movement. The model simulates the wave-induced near bottom water dynamics based on meteorological data. First, the wave's characteristics in deep water are calculated. Then the gradual change of the wave's characteristics is calculated as it reaches shallower water. The maximum near-bottom orbital velocity is calculated for the entire fetch distance, and the wave's ability to resuspend fine-grained particles is determined using well-known semiempirical methods. A large variety of weather conditions are simulated and the results are shown as a map for two different bottom types: accumulated bottoms (continual accumulation of fine grained particles and any radionuclides present) and erosional/accumulation bottoms (periods with accumulation alternating with periods with erosion). The model has been calibrated for four areas close to SFR-1, which provides a range of different sedimentation conditions. Since shore displacement is positive, currently approximately 60 cm per century, sedimentation conditions have fluctuated and will continue to

  11. Variability of sediment transport in beach and coastal dune environments, Brittany, France

    Science.gov (United States)

    Regnauld, Hervé; Louboutin, Roland

    2002-06-01

    On the coasts of Brittany (English Channel and Bay of Biscay), barrier systems were surveyed between 1995 and 2000. The beach profiles have a very high variability, which cannot be statistically explained by linear correlation with the wind, the waves, or the tides. The behaviour of the profile is represented on a phase diagram (speed of profile change: Y-axis, thickness of the profile: X-axis). The points in the center of the profile "rotate" around an average equilibrium which is seldom measured in the field. The seaward edge of the beaches oscillates between loss and gain, but with a net positive budget. The landward top of the beach displays a range of oscillations. The dunes always have a positive budget. The whole behaviour of the system is explained if the precise succession of anticyclonic and cyclonic winds is taken into account. Long periods of easterly winds (offshorewards) tend to produce a calm sea and to increase tidal sediment settling on the seafloor. If an onshore westerly storm occurs just after such a period, it hits a sediment-rich environment and produces a net accumulation on both the beach and the dunes. Periods of westerly calm to moderate winds do not help accumulation: a full going storm will hit a depleted environment and produce erosion. The speed of dune accretion and the budget of the beaches seem to partly depend on the ratio of cyclonic to anticyclonic conditions.

  12. Bioprospecting Sediments from Red Sea Coastal Lagoons for Microorganisms and Their Antimicrobial Potential

    KAUST Repository

    Al-Amoudi, Soha

    2016-12-08

    Since the soils nutrient composition along with the associated biotic and abiotic factors direct the diversity of the contained microbiome and its potential to produce bioactive compounds, many studies have been focused on sediment types with unique features characteristic of extreme environments. Red Sea lagoon ecosystems are environments with such unique features as they are highly saline. However, not much is known about the potential of their microbiomes to produce bioactive compounds. Here, we explored sediment types such as mangrove mud, microbial mat, and barren soil collected from Rabigh harbor lagoon (RHL) and Al-Kharrar lagoon (AKL) as sources for antibiotic bioprospecting. Our antibiotic bioprospecting process started with a metagenomic study that provides a more precise view of the microbial community inhabiting these sites and serves as a preliminary screen for potential antibiotics. Taking the outcomes of the metagenomic screening into account, the next step we established a library of culturable strains from the analyzed samples. We screened each strain from that library for antibiotic activity against four target strains (Staphylococcus aureus ATCC 25923, Escherichia coli dh5 α, Pseudomonas syringae pv. tomato dc3000 and Salmonella typhimurium dt2) and for the presence of polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) genes known to support synthesis of secondary metabolites that act like antimicrobial agents. The metagenomics study showed a shift in dominant phyla consistent with a historical exposure to hydrocarbon contamination and that AKL unexpectedly displayed more contamination than RHL. This may be due to dominant phyla in AKL being consistent with early hydrocarbon exposure (when contamination levels are still high) and the dominant phyla in RHL being consistent with late hydrocarbon exposure (when contamination levels are lower as a result of an extended period of hydrocarbon degradation). Additionally, RHL samples

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

    DEFF Research Database (Denmark)

    KUHL, M.; JØRGENSEN, BB

    1994-01-01

    radiance distribution. Comparison of light fields in wet and dry quartz sand showed that the lower refractive index of air than of water caused a more forward-biased scattering in wet sand. Light penetration was therefore deeper and surface irradiance reflectance was lower in wet sand than in dry sand......The light field in coastal sediments was investigated at a spatial resolution of 0.2-0.5 mm by spectral measurements (450-850 nm) of field radiance and scalar irradiance using fiber-optic microprobes. Depth profiles of field radiance were measured with radiance microprobes at representative angles...... relative to vertically incident collimated light in rinsed quartz sand and in a coastal sandy sediment colonized by microalgae. Upwelling and downwelling components of irradiance and scalar irradiance were calculated from the radiance distributions. Calculated total scalar irradiance agreed well...

  14. Pollution status of polycyclic aromatic hydrocarbons in surface sediments from the Yangtze River Estuary and its adjacent coastal zone.

    Science.gov (United States)

    Wang, Chenglong; Zou, Xinqing; Gao, Jianhua; Zhao, Yifei; Yu, Wenwen; Li, Yali; Song, Qiaochu

    2016-11-01

    Polycyclic aromatic hydrocarbons (PAHs) are mainly produced by incomplete combustion and are used as indicators of anthropogenic activities on the environment. This study analyses the PAHs level in the Yangtze River Estuary (YRE), an important component of Yangtze River and a developed and populated region in China. Surface sediments were collected from 77 sites at the YRE and its adjacent coastal zone (IACZ) for a comprehensive study of PAHs. Kriging interpolation technology and Positive matrix factorization (PMF) model were applied to explore the spatial distribution and sources of PAHs. Concentrations of 16 PAHs (ΣPAHs) varied from 27.2 ng g(-1) to 621.6 ng g(-1) dry weight, with an average value of 158.2 ng g(-1). Spatially, ΣPAHs exhibited wide fluctuation and exhibited an increasing tendency from north to south. In addition, ΣPAHs exhibited a decreasing trend with increasing distance between the estuary and IACZ. The deposition flux of PAHs indicated that more than 107.8 t a(-1) PAHs was deposited in the study area annually. The results of the PMF model revealed that anthropogenic activities were the main sources of PAHs in the study area. Vehicle emissions and marine engines were the most important sources and accounted for 40.9% of the pollution. Coal combustion, petrogenic sources, and wood combustion were other sources that contributed 23.9%, 23.6%, and 11.5%, respectively. The distribution patterns of PAHs in the YRE and IACZ were influenced by many complicated factors such as sediment grain size, hydrodynamics and so on. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Storm-related sedimentation influenced by coastal configuration in the stratigraphic record of a tectonically active shelf (Upper Pleistocene Le Castella terrace, Italy)

    Science.gov (United States)

    Nalin, Ronald; Massari, Francesco

    2018-03-01

    Analysis of patterns of coastal circulation and sediment dispersal is an essential step for the study of controlling factors influencing the long-term dynamics of coastal systems. Modern settings offer the possibility to monitor relevant parameters over relatively short time spans. However, geological examples complement this perspective by providing a time-averaged record where longer trends and stratigraphically significant processes can be evaluated. This study investigates the shallow marine deposits of Le Castella terrace (Upper Pleistocene, southern Italy) to document how patterns of circulation influenced by coastline configuration can affect the preserved millennial-scale depositional record of a progradational shoreline system. The regressive portion of the Le Castella terrace deposits, developed during a relative sea-level highstand and falling stage, consists of a progradational wedge mainly composed of redistributed skeletal particles of a coeval shallow water carbonate factory. Preservation of the morphology of the paleocoastline and abundant current-related sedimentary structures allow reconstruction of the predominant sediment dispersal dynamics responsible for the formation of this sedimentary wedge. Facies and paleocurrent analysis indicate offshore and alongshore sediment transport modes, consistent with coastal circulation driven by storms normally incident to the shoreline and a sharp change in coastline orientation. This coastal inflection influenced circulation patterns causing flow separation and eddy formation in the lee of the curved coastline. Syndepositional tectonic deformation also affected the architecture of the preserved deposits, controlling the nucleation and development of a clinostratified body and determining localized lateral stratigraphic variability. This study illustrates how transient but recurrent circulation patterns associated with changes in coastal orientation and related to high-energy storm events can leave a

  16. Sediment contribution from coastal-cliff erosion into the Nile's littoral cell and its significance to cliff-retreat mitigation efforts

    Science.gov (United States)

    Katz, Oded; Mushkin, Amit; Crouvi, Onn; Alter, Samuel; Shemesh, Ran

    2017-04-01

    In 2013 the government of Israel initiated a national mitigation program aimed to prevent further collapse and retreat of the country's coastal cliffs, which occur along the northern termination of the Niles's littoral cell (NLC) in the eastern Mediterranean. The goals of this large-scale program are to protect infrastructure and property proximal to the cliff and to conduct long-term maintenance and monitoring of this highly dynamic and sensitive land-sea interface that spans 40 km of Israel's coast line. Here, we examine the possible impact of proposed cliff retreat mitigation efforts on long-shore sediment transport (LST) and coastal dynamics in the region. We used airborne LiDAR spanning a 9-year period between 2006 and 2015 to quantify the annual contribution of sediment eroded from a 20-km-long segment of Israel's coastal cliffs into the NLC. Our measurements reveal 282±85*103 m3 of sediment eroded from the cliff and delivered into the NLC during the studied period. Considering our study area comprises 50% of Israel's sea cliffs we infer an average contribution rate of 30,000-60,000 m^3/yr of cliff-derived sediment into the NLC prior to the planned broad-scale implementation of cliff-retreat mitigation measures. Previous studies report an average net LST flux of 80,000 - 90,000 m3 that reaches the northern termination of the NLC at Haifa Bay annually. Thus, our results suggest that Israel's actively eroding coastal cliffs are primary contributors (40-80%) to the LST budget along the northern termination of the NLC. It therefore appears that successful implementation of the coastal-cliff protection program along Israel's coastline will result in a significant sand deficit, which may drive LST in this part of the NLC out of its 'background' state. In the likely case that the energy/currents driving LST do not change, a possible outcome of this sediment deficit could be increased beach erosion along Israel's coast line to make up for the lost volumes of cliff

  17. Determination of Irgarol-1051 and its related s-triazine species in coastal sediments and mussel tissues by HPLC-ESI-MS/MS.

    Science.gov (United States)

    Tsang, Vic Wing-Hang; Lei, Ngai-Yu; Lam, Michael Hon-Wah

    2009-10-01

    A mild, low-temperature analytical approach based on sonication assisted extraction coupled with HPLC electrospray ionization triple quadrupole tandem mass spectrometry has been developed for the simultaneous qualitative and quantitative determination of the four Irgarol-related s-triazine species, namely Irgarol-1051, M1, M2 and M3, in coastal sediments and Green-lipped mussel samples. Mild extraction conditions were necessary for the preservation of the thermally unstable M2. The Multiple Reaction Monitoring (MRM) mode of detection by ESI-MS/MS enabled reliable qualitative identification and sensitive quantitative determination of those s-triazines. This determination method was applied to evaluate the degree of Irgarol-1051 contamination in the sediments and biota of the coastal environment of Hong Kong--one of the busiest maritime ports in the world. All the four s-triazine species were observed in all of the samples. This is the first time that the newly identified M2 and M3 are detected in coastal sediments and biota tissues.

  18. Response of core microbial consortia to hydrocarbon contaminations in coastal sediment habitats

    Directory of Open Access Journals (Sweden)

    Mathilde Jeanbille

    2016-10-01

    Full Text Available Traditionally, microbial surveys investigating the effect of chronic anthropogenic pressure such as polyaromatic hydrocarbons (PAHs contaminations consider just the alpha and beta diversity and ignore the interactions among the different taxa forming the microbial community. Here, we investigated the ecological relationships between the three domains of life (i.e. Bacteria, Archaea and Eukarya using 454 pyrosequencing data of the 16S rRNA and 18S rRNA genes from chronically impacted and pristine sediments, along the coasts of the Mediterranean Sea (Gulf of Lion, Vermillion coast, Corsica, Bizerte lagoon and Lebanon and the French Atlantic Ocean (Bay of Biscay and English Channel. Our approach provided a robust ecological framework for the partition of the taxa abundance distribution into 859 core OTUs and 6629 satellite OTUs. OTUs forming the core microbial community showed the highest sensitivity to changes in environmental and contaminant variations, with salinity, latitude, temperature, particle size distribution, total organic carbon (TOC and PAH concentrations as main drivers of community assembly. The core communities were dominated by Gammaproteobacteria and Deltaproteobacteria for Bacteria, by Thaumarchaeota, Bathyarchaeota and Thermoplasmata for Archaea and Metazoa and Dinoflagellata for Eukarya. In order to find associations among microorganisms, we generated a co-occurrence network in which PAHs were found to impact significantly the potential predator – prey relationship in one microbial consortium composed of ciliates and Actinobacteria. Comparison of network topological properties between contaminated and non-contaminated samples showed substantial differences in the structure of the network and indicated a higher vulnerability to environmental perturbations in the contaminated sediments.

  19. Ammonia-oxidizing bacteria and archaea in wastewater treatment plant sludge and nearby coastal sediment in an industrial area in China.

    Science.gov (United States)

    Zhang, Yan; Chen, Lujun; Sun, Renhua; Dai, Tianjiao; Tian, Jinping; Wen, Donghui

    2015-05-01

    Under the increasing pressure of human activities, Hangzhou Bay has become one of the most seriously polluted waters along China's coast. Considering the excessive inorganic nitrogen detected in the bay, in this study, the impact of an effluent from a coastal industrial park on ammonia-oxidizing microorganisms (AOMs) of the receiving area was interpreted for the first time by molecular technologies. Revealed by real-time PCR, the ratio of archaeal amoA/bacterial amoA ranged from 5.68 × 10(-6) to 4.79 × 10(-5) in the activated sludge from two wastewater treatment plants (WWTPs) and 0.54-3.44 in the sediments from the effluent receiving coastal area. Analyzed by clone and pyrosequencing libraries, genus Nitrosomonas was the predominant ammonia-oxidizing bacteria (AOB), but no ammonia-oxidizing archaea (AOA) was abundant enough for sequencing in the activated sludge from the WWTPs; genus Nitrosomonas and Nitrosopumilus were the dominant AOB and AOA, respectively, in the coastal sediments. The different abundance of AOA but similar structure of AOB between the WWTPs and nearby coastal area probably indicated an anthropogenic impact on the microbial ecology in Hangzhou Bay.

  20. High resolution LiDAR measurements reveal fine internal structure and variability of sediment-carrying coastal plume

    Science.gov (United States)

    Zavialov, P. O.; Pelevin, V. V.; Belyaev, N. A.; Izhitskiy, A. S.; Konovalov, B. V.; Krementskiy, V. V.; Goncharenko, I. V.; Osadchiev, A. A.; Soloviev, D. M.; Garcia, C. A. E.; Pereira, E. S.; Sartorato, L.; Moller, O. O.

    2018-05-01

    We report results of a field survey conducted in the buoyant, sediment-carrying coastal plume generated by the discharge from the Patos Lagoon, the World's largest choked lagoon. The concentration of total suspended matter (TSM) and organic matter (as represented by total organic carbon, TOC) were mapped using an ultraviolet fluorescent LiDAR, which allowed for extensive data coverage (total of 79,387 simultaneous determinations of TSM and TOC) during 3 consecutive days. These observations were accompanied by hydrographic measurements from the ship and at a mooring station. We first describe synoptic variability of the plume, which responded energetically to wind forcing. We then analyze the TSM, TOC and hydrographic data jointly and develop a simple approach to estimate the rates of suspended matter removal from the upper layer due to gravitational settling and turbulent mixing based on relative changes in TSM and TOC concentrations. Four distinct regions within the plume exhibiting different dynamics of suspended and dissolved constituents were identified on this basis.

  1. Enrichment using an up-flow column reactor and community structure of marine anammox bacteria from coastal sediment.

    Science.gov (United States)

    Kindaichi, Tomonori; Awata, Takanori; Suzuki, Yuji; Tanabe, Katsuichiro; Hatamoto, Masashi; Ozaki, Noriatsu; Ohashi, Akiyoshi

    2011-01-01

    We established an enrichment culture of marine anaerobic ammonium oxidation (anammox) bacteria using an up-flow column reactor fed with artificial sea water supplemented with nitrogen and minerals and inoculated with coastal surface sediment collected from Hiroshima Bay. After 2 months of reactor operation, simultaneous removal of NH(4)(+) and NO(2)(-) was observed, suggesting that an anammox reaction was proceeding. A total nitrogen removal rate of 2.17 g-N L(-1) day(-1) was attained on day 594 while the nitrogen loading rate was 3.33 g-N L(-1) day(-1). Phylogenetic analysis revealed that at least two dominant "Candidatus Scalindua" species were present in this reactor. Moreover, many uncultured bacteria and archaea, including candidate division or ammonia-oxidizing archaea, were present. Fluorescence in situ hybridization (FISH) revealed that anammox bacteria accounted for 85.5 ± 4.5% of the total bacteria at day 393. We also designed two oligonucleotide probes specific to each dominant "Candidatus Scalindua" species. A simultaneous FISH analysis using both probes showed that two different "Candidatus Scalindua" species were clearly recognizable and coexisted during reactor operation, although there was some variation in their abundance. The marine anammox bacteria enriched in this study have potential applications to the treatment of industrial wastewater containing high levels of ammonium and salt.

  2. Uranium isotopes in rivers, estuaries and adjacent coastal sediments of western India: their weathering, transport and oceanic budget

    International Nuclear Information System (INIS)

    Borole, D.V.; Krishnaswami, S.; Somayajulu, B.L.K.

    1982-01-01

    The two major river systems on the west coast of India, Narbada and Tapti, their estuaries and the coastal Arabian sea sediments have been extensively studied for their uranium concentrations and 234 U/ 238 U activity ratios. The 238 U concentrations in the aqueous phase of these river systems exhibit a strong positive correlation with the sum of the major cations, and with the HCO 3 - ion contents. The abundance ratio of dissolved U to the sum of the major cations in these waters is similar to their ratio in typical crustal rocks. In the estuaries, both 238 U and its great-grand daughter 234 U behave conservatively beyond chlorosities 0.14 g/l. A review of the uranium isotope measurements in river waters yield a discharge weighted-average 238 U concentration of 0.22 μg/l with a 234 U/ 238 U activity ratio of 1.20 +-0.06. The residence time of uranium isotopes in the oceans estimated from the 238 U concentration and the 234 U/ 238 U A.R. of the rivers yield conflicting results; the material balance of uranium isotopes in the marine environment still remains a paradox. If the disparity between the results is real, then an additional 234 U flux of about 0.25 dpm/cm 2 .10 3 yr into the oceans is necessitated. (author)

  3. Distinct microbial populations are tightly linked to the profile of dissolved iron in the methanic sediments of the Helgoland mud area, North Sea

    Directory of Open Access Journals (Sweden)

    Oluwatobi Emmanuel Oni

    2015-05-01

    Full Text Available Iron reduction in subseafloor sulfate-depleted and methane-rich marine sediments is currently a subject of interest in subsurface geomicrobiology. While iron reduction and microorganisms involved have been well studied in marine surface sediments, little is known about microorganisms responsible for iron reduction in deep methanic sediments. Here, we used quantitative PCR (Q-PCR-based 16S rRNA gene copy numbers and pyrosequencing-based relative abundances of bacteria and archaea to investigate covariance between distinct microbial populations and specific geochemical profiles in the top 5 m of sediment cores from the Helgoland mud area, North Sea. We found that gene copy numbers of bacteria and archaea were specifically higher around the peak of dissolved iron in the methanic zone (250-350 cm. The higher copy numbers at these depths were also reflected by the relative sequence abundances of members of the candidate division JS1, methanogenic and Methanohalobium/ANME-3 related archaea. The distribution of these populations was strongly correlated to the profile of pore-water Fe2+ while that of Desulfobacteraceae corresponded to the pore-water sulfate profile. Furthermore, specific JS1 populations also strongly co-varied with the distribution of Methanosaetaceae in the methanic zone. Our data suggest that the interplay among JS1 bacteria, methanogenic archaea and Methanohalobium/ANME-3-related archaea may be important for iron reduction and methane cycling in deep methanic sediments of the Helgoland mud area and perhaps in other methane-rich depositional environments.

  4. Progress in Management of Sediment Bypassing at Coastal Inlets: Natural Bypassing, Weir Jetties, Jetty Spurs, and Engineering Aids in Design

    National Research Council Canada - National Science Library

    Seabergh, William C; Kraus, Nicholas C

    2003-01-01

    .... Artificial bypassing mimics or preserves the pathways of sediment in the littoral zone and harmonizes the requirement for deepening navigation channels within the context of the natural sediment...

  5. Mercury concentration in the sediments as a function of changing climate in coastal zone of Southern Baltic Sea – preliminary results

    Directory of Open Access Journals (Sweden)

    Bełdowska M.

    2013-04-01

    Full Text Available Mercury, despite of its many uses in industry, is also highly toxic. It is highly neurotoxic, and because of the ability of mercury to penetrate placental barrier, in some countries ban on predatory fish consumption (the main route of mercury into human organism by pregnant women was introduced. There are very little publications describing the consequences of weather anomalies on contaminants cycles. No research was published concerning the reemission of Hg due to climate change in the Southern Baltic Sea. The study area was situated in the coastal zone of the Gulf of Gdansk - the Southern Baltic. Samples of different species of macrophytobenthos were collected once a month during 2006-2012. Samples of Potamogeton pectinatus, sediments and pore waters were collected once a month from February 2011 to January 2012. The climate changes in the moderate latitudes: extension of the fall season, has contributed to stabilization of high concentrations of mercury in pore waters. Lack of ice cover in the coastal zone and simultaneous occurrence of storms had an impact on supply of the organic matter to the sediments and the increased concentration of Hg. More intense burning of fossil fuels in this season favored the increased metal concentration in the atmosphere and consequently an increase of the atmospheric deposition of metals to the sediments. This led to a fourfold increase of the mercury concentration in sediments as compared to fall season.

  6. Microelectrode Studies of Seasonal Oxygen-Uptake in a Coastal Sediment - Role of Molecular-Diffusion

    DEFF Research Database (Denmark)

    RASMUSSEN, H.; JØRGENSEN, BB

    1992-01-01

    in the bay varied from 100 % air saturation during winter to 23 % during summer. The potentially higher O2 respiration during the summer months was counteracted by a lower O2 concentration in the bottom water, which led to a small seasonal variation in O2 uptake. Depth of the oxic sediment zone reached 5.1...... surface zone. The O2 consumption rates in the oxic surface layer, calculated from (b) and (c) using molecular diffusion coefficients of O2, closely agreed and accounted for 70 % of the total O2 uptake. The O2 uptake rates strongly depended on in situ O2 concentrations in the overlying seawater, which...... mm during winter, narrowed down rapidly to a few mm upon settling of a spring phytoplankton bloom, and was only 1.2 mm during summer. Modeling of O2 consumption from O2 microprofiles showed zero-order kinetics, i.e. constant O2 consumption rates throughout the oxic zone during winter. Enhanced O2...

  7. Roseimarinus sediminis gen. nov., sp. nov., a facultatively anaerobic bacterium isolated from coastal sediment.

    Science.gov (United States)

    Wu, Wen-Jie; Liu, Qian-Qian; Chen, Guan-Jun; Du, Zong-Jun

    2015-07-01

    A Gram-stain-negative, facultatively anaerobic, non-motile and pink-pigmented bacterium, designated strain HF08(T), was isolated from marine sediment of the coast of Weihai, China. Cells were rod-shaped, and oxidase- and catalase-positive. The isolate grew optimally at 33 °C, at pH 7.5-8.0 and with 2-3% (w/v) NaCl. The dominant cellular fatty acids were iso-C15 : 0, anteiso-C15 : 0 and iso-C14 : 0. Menaquinone 7 (MK-7) was the major respiratory quinone and the DNA G+C content was 44.8 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolate was a member of the class Bacteroidia, and shared 88-90% sequence similarity with the closest genera Sunxiuqinia, Prolixibacter, Draconibacterium, Mariniphaga and Meniscus. Based on the phylogenetic and phenotypic evidence presented, a novel species in a new genus of the family Prolixibacteraceae is proposed, with the name Roseimarinus sediminis gen. nov., sp. nov. The type strain of Roseimarinus sediminis is HF08(T) ( = KCTC 42261(T) = CICC 10901(T)).

  8. Offsets in radiocarbon ages between plants and shells from same horizons of coastal sediments in Korea

    Energy Technology Data Exchange (ETDEWEB)

    Nakanishi, Toshimichi [Geologic Environment Division, Korea Institute of Geoscience & Mineral Resources, Gajeong-dong 30, Yuseong-gu, Daejeon (Korea, Republic of); Hong, Wan, E-mail: whong@kigam.re.kr [Geologic Environment Division, Korea Institute of Geoscience & Mineral Resources, Gajeong-dong 30, Yuseong-gu, Daejeon (Korea, Republic of); Sung, Ki Suk [Geologic Environment Division, Korea Institute of Geoscience & Mineral Resources, Gajeong-dong 30, Yuseong-gu, Daejeon (Korea, Republic of); Carbon Analysis Laboratory (CAL), 25, 114 Gil, Taejeon-ro, Dong-gu, Daejeon (Korea, Republic of); Sung, Kil Ho [Geologic Environment Division, Korea Institute of Geoscience & Mineral Resources, Gajeong-dong 30, Yuseong-gu, Daejeon (Korea, Republic of); University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon (Korea, Republic of); Nakashima, Rei [Institute of Geology & Geoinformation, Advanced Industrial Science & Technology, Higashi 1-1-1, Tsukuba, Ibaraki (Japan)

    2015-10-15

    To measure the spatial and chronological changes of the reservoir effect around the Korean Peninsula, the radiocarbon ages of 38 marine shell and terrestrial plant pairs from the same horizons of six cores of Holocene sediments collected from the southern coast and western coast sites of the peninsula were measured. These reservoir ages (R) were distributed in the range of 430 ± 190 yrs within 60 ± 60 to 1000 ± 60 yrs starting in 9000 cal BP. The average R values of the cores obtained from large rivers, such as the S13 and YAR-4 cores (340 and 190 yrs), were clearly smaller than the R values of the sites far from a large river, such as the S15 and W09 cores (470 and 650 yrs). This is thought to be associated with the mixing process of old brine and young freshwater. On the other hand, the R values of the S13, W17, and YAR-4 cores gradually increased during the time span from 6700 to 8200 cal BP. The R values for the S15 core also increased in the period from 2800 to 3800 cal BP. Such tendencies result from the mixing ratio increase of brine due to the rising sea level.

  9. Environmental impact of aquaculture-sedimentation and nutrient loadings from shrimp culture of the southeast coastal region of the Bay of Bengal.

    Science.gov (United States)

    Das, Biplob; Khan, Yusuf Sharif Ahmed; Das, Pranab

    2004-01-01

    Nutrient loadings were measured for surface seawater and bottom sediments of semi-intensive and improved extensive shrimp culture pond, adjacent estuary, and fallow land in the south-east coastal region of Bangladesh during August, 2000-January, 2001 to evaluate the impact of shrimp culture. The mean levels of nutrients found in the pond surface water were 108.780 mg/L for CaCO3, 0.526 mg/L for NH4+ -N, 3.075 wt% for organic carbon, 7.00 mg/L for PO4-P, 5.57 mg/L for NO3-N, and 7.33 mg/L for chlorophyll-a. The maximum mean value of H2S (0.232 mg/L) was found in estuarine water. Nutrients loading were found to be decreased with distance from the shrimp farm discharge unit in estuarine water. The mean level of organic matter, total nitrogen, and organic carbon were found in higher concentrations in sediments of cultured pond compared to bottom soil of adjacent fallow land at the same elevation. Extractable Ca values were found in higher concentration (550.33 ppt) in adjacent fallow land, as the shrimps for molting in shrimp ponds use extractable Ca. The relation between seawater H2S value and sediment pH (r = - 0.94); sediment organic carbon and sediment pH values (r = -0.76), sediment total nitrogen and sediment pH (r = -0.74) were found to be highly negatively correlated. Whereas the relation between seawater H2S value and sediment total nitrogen (r = 0.92), water NH4+ -N and sediment pH (r = 0.66) were found to be positively correlated. The results revealed that load of nutrients at eutrophic level in estuarine water, and decrease of soil pH; leading to acid sulphate soil formation indicates a negative impact of shrimp culture.

  10. Variation of 231Pa, 230Th and 231Paex/230Thex in surface sediments of the Sabah-Sarawak coastal waters

    International Nuclear Information System (INIS)

    Zal U'yun Wan Mahmood; Zaharudin Ahmad; Abdul Kadir Ishak; Norfaizal Mohamed; Che Abd Rahim Mohamed

    2011-01-01

    Protactinium and thorium activities were measured in eight surface sediment taken in 2004 to determine effectiveness scavenging of 231 Pa at Sabah-Sarawak coastal waters. The result found that activity ratios of 231 Pa ex / 230 Th ex were ranged from 0.07 to 0.13 at all sampling stations. The high 231 Pa ex / 230 Th ex activity ratio than the production ratio of 0.093 in seawater at station SR 01, SR 02, SR 04, SB 02 and SB 05, revealed that 231 Pa is effectively removed from the water column into the sediment in comparison with 230 Th at those stations. Low percentage of 230 Th ex (90-95%) in comparison with 231 Pa ex at all stations can be attributed to less efficiently scavenged of 230 Th onto particles prior deposited at the marine sediment bed. (author)

  11. Impact of total organic carbon (in sediments) and dissolved organic carbon (in overlying water column) on Hg sequestration by coastal sediments from the central east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Chakrabortya, P.; Sharma, B.M.; Babu, P.V.R.; Yao, K.M.; Jaychandran, S.

    , 1991; Liu et al., 2006; Tack and Verloo, 1995). Mercury accumulates in sediment globally from many physical, chemical, biological, geological and anthropogenic environmental processes. Thus, sediment can be a good indicator of water quality of a...-Black method (Schumacher, 2002). This method has been widely used for the determination of total organic carbon in the soil and sediments. 3.0 Results and discussion The general description and texture analysis of the studied sediments are presented...

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

    Science.gov (United States)

    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.

  13. Identification and determination of the contribution of iron-steel manufacturing industry to sediment-associated polycyclic aromatic hydrocarbons (PAHs) in a large shallow lake of eastern China.

    Science.gov (United States)

    Zhang, Liu; Bai, Ya-Shu; Wang, Ji-Zhong; Peng, Shu-Chuan; Chen, Tian-Hu; Yin, Da-Qiang

    2016-11-01

    Seventeen polycyclic aromatic hydrocarbon (PAH) compounds were determined in surface sediments collected from the Chaohu Lake (a large shallow lake in eastern China) and its tributaries. Both diagnostic ratios and a receptor model (positive matrix factorization, PMF) were applied to identify and determine the contribution of a local iron-steel manufacturing plant located in the Nanfei River (NFR) to the Chaohu Lake basin. The results show that sites located in the downstream of the steel plant contained concentrations of 17 PAH (Σ 17 PAH) approximately two orders of magnitudes higher than those from other sites. Five factors were identified by the PMF model, including industrial waste, wood/biomass burning, diagenetic origin, domestic coal combustion, and industrial combustion. Our findings suggest that sediments in the downstream of the plant and in the western part of the Chaohu Lake were predominantly affected by industrial coal combustion. A mixture of pyrolytic origins impacted urban sediments in the upstream of the plant, whereas diagenetic origins along with coal and biomass burning were suggested to influence the eastern part and rural tributaries of the lake. To assess the potential ecological risk and toxicity caused by the iron-steel plant, sediment toxicity was evaluated by the PMF model, sediment quality guideline, and toxic equivalent factors. All of the three approaches suggested PAH accumulation in the NFR sediments could produce significant adverse ecological effects and half of the sediment toxicity in the NFR may be attributed to the emissions from the iron-steel plant. Some rural locations also exhibited PAH concentrations above probable effects, most likely contributed by wood/biomass burning.

  14. Microbial iron reduction and methane oxidation in subsurface sediments of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, C.E.G.; Judith, M.; Gonsalves, M.J.B.D.; Nazareth, D.R.; Nagarchi, L.; Kamaleson, A.S.

    as it has productivity driven seasonal pattern of dioxygen-deficient waters. It is one of the most biologically productive regions of the world’s ocean having a characteristic seasonal upwelling followed by the production of an oxygen minimum zone... in the water body (Wyrtki, 1971; Madhupratap et al., 1996; Naidu, 1998). The seasonal upwelling in return has been reported to have prolonged and distinct effect on biological production and sedimentation (Madhupratap et al., 1996). Another important feature...

  15. Oceanic and coastal dissolved iron observations from 1978-01-01 to 2004-12-31 (NCEI Accession 0067344)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Keith Moore observational dissolved Iron database. Moore expanded the original iron database complied by Parekh et al. (2005. The complete dataset with references to...

  16. Immobilization of mercury in field soil and sediment using carboxymethyl cellulose stabilized iron sulfide nanoparticles

    Science.gov (United States)

    Gong, Yanyan; Liu, Yuanyuan; Xiong, Zhong; Kaback, Dawn; Zhao, Dongye

    2012-07-01

    Mercury (Hg) is one of the most pervasive and bio-accumulative metals in the environment. Yet, effective in situ remediation technologies have been lacking. This study investigated the effectiveness of a class of soil-deliverable FeS nanoparticles for in situ immobilization of Hg in two field-contaminated soils from a New Jersey site and one sediment from an Alabama site. The nanoparticles were prepared using sodium carboxymethyl cellulose (CMC) as a stabilizer. Transmission electron microscopy measurements revealed a particle size of 34.3 ± 8.3 nm (standard deviation), whereas dynamic light scattering gave a hydrodynamic diameter of 222.5 ± 3.2 nm. Batch tests showed that at an FeS-to-Hg molar ratio of 28:1-118:1, the nanoparticles reduced water-leachable Hg by 79%-96% and the TCLP (toxicity characteristic leaching procedure) based leachability by 26%-96%. Column breakthrough tests indicated that the nanoparticles were deliverable in the sediment/soil columns under moderate injection pressure. However, once the external pressure was removed, the delivered nanoparticles remained virtually mobile under typical groundwater flow conditions. When the Hg-contaminated soil and sediment were treated with 52-95 pore volumes of a 500 mg l-1 FeS nanoparticle suspension, water-leachable Hg was reduced by 90%-93% and TCLP-leachable Hg was reduced by 65%-91%. The results warrant further field demonstration of this promising in situ remediation technology.

  17. Organic matter composition in the sediment of three Brazilian coastal lagoons: district of Macaé, Rio de Janeiro (Brazil

    Directory of Open Access Journals (Sweden)

    Klaus-Gerhard Zink

    2004-03-01

    Full Text Available Freshwater lagoons comprise important coastal ecosystems and natural buffers between urbanized land areas and open ocean in the Rio de Janeiro State, Brazil. Studies of sediment and water chemistry, zooplankton and bacterial communities to assess the extent of anthropogenic disturbance are available. Here we contribute with an organic-geochemical approach supplemented by some microbiological aspects to complete the characterization of these lagoonal ecosystems. Bulk organic matter and extractable lipids (aliphatic hydrocarbons, alcohols and fatty acids, sterols were investigated from two locations per lagoon: at the seaward site and landward ends - and at two depth intervals (0-3 and 3-6 cm per site. Urbanized Imboacica Lagoon received increased anthropogenic input over the most recent years represented by the topmost 3 cm of sediment, whereas deeper sediment layers are less affected by human influence. Eutrophication or nutrient availability favored enhanced algal/cyanobacterial growth. In remote Cabiúnas and Comprida Lagoons pristine conditions are preserved. Organic matter from vascular plants dominates (chain length of free lipids up to C36, which is exceptionally well preserved by acidic lagoonal waters. Differentiation between landward and seaward sites in these two lagoons is less well established due to much smaller surface/volume to catchment ratios. No anthropogenic influences are yet detectable in sediments of Cabiúnas and Comprida Lagoons.As lagoas costeiras são importantes ecossistemas costeiros no Estado do Rio de Janeiro, localizadas entre áreas urbanizadas da costa e o oceano aberto. Vários estudos enfocando o sedimento, a água, a comunidade zooplanctônica e comunidades bacterianas demonstraram a extensão da influência antrópica sobre estes ecossistemas aquáticos. Neste estudo foi investigada a composição da matéria orgânica presente no sedimento, assim como, alguns parâmetros microbiológicos, com o intuito de

  18. Iron isotope constraints on arsenic release from Mekong Delta sediments, Cambodia

    Science.gov (United States)

    Matsumoto, T.; Yamaguchi, K. E.; Hirata, T.; Yamagata, Y.; Yamaguchi, A.; Abe, G.

    2017-12-01

    Arsenic-contaminated groundwater is a world-wide environmental problem and threatens more than 100 million people living in delta areas of South, SE and East Asia. It is typically associated with reducing aquifers with organic-rich alluvial sediments, little thermal gradients, low sulfate concentrations, and slow flushing rates. Such conditions are typical for low-lying countries in Asian deltas; however, compared to Bangladesh, Cambodia has received far less attention. Upon reductive dissolution of Fe-(oxyhydr)oxides that adsorbed As, Fe and As are released into solution as dissolved Fe2+ and arsenate, respectively. Following the oxidation of dissolved Fe2+, newly-formed Fe-(oxyhydr)oxides adsorb As again. Thus, in anoxic waters, concentrations of As correlate with those of dissolved Fe2+. Fluctuating redox conditions in the aquifer are control As release, although inhibition of adsorption of arsenate and arsenite onto the Fe-(oxyhydr)oxides occurs when the concentrations of phosphate, bicarbonate, silicate, and/or organic matter become sufficiently high. Biogeochemical redox reactions of Fe result in significant isotope fractionation (e.g., Johnson et al., 2008). We hypothesized that magnitude of isotope fractionation of Fe in the aquifer sediments, reflecting repeated (incomplete) redox reactions of Fe, may be proportional to the amount of total As release. We aim to calibrate the As release from aquifer sediment by Fe isotope analysis. As a preliminary study, series of sediment samples were collected from the Mekong Delta, Cambodia, in September 2016. Based on measurements by XRF, ICP-AES and ICP-MS, concentrations of As varied significantly covering the range from 4.5 to 15.5 µg/g with a median value of 11 µg/g (higher than the average crustal value of 5 µg/g), and those of Fe is from 2.6 to 9.7 wt.% with a median value of 7.1 wt.%. Concentrations of As and Fe show positive correlation (R2 = 0.72), indicating an effective redox cycling of Fe and As as

  19. Polycyclic aromatic hydrocarbons in the coastal sea water, the surface sediment and Mudskipper Boleophthalmus dussumieri from coastal areas of the Persian Gulf: source investigation, composition pattern and spatial distribution.

    Science.gov (United States)

    Sinaei, Mahmood; Mashinchian, Ali

    2014-03-10

    Persian Gulf is an exposed and stressed area as a result of oil pollution and other fossil fuels containing PAHs. The susceptibility of using mudskippers to monitor marine pollution, like PAHs, points to the fact that mudskippers are able to accumulate and record the PAHs presented in the coastal environments. Polycyclic aromatic hydrocarbons (PAHs) were examined in the coastal waters, the sediments and biota (i.e., Boleophthalmus dussumieri) along the coast of the Persian Gulf. PAHs concentrations were measured with HPLC method. Total PAH concentrations in the sea water, the sediments, the liver and the gill tissues ranged between 0.80-18.34 μg/l, 113.50-3384.34 ng g-1 (d w), 3.99-46.64 ng g-1 (d w) and 3.11-17.76 ng g-1 (d w), respectively. PAHs distribution patterns in the sediment and the liver tissue samples were dominated by three-and four-ring structures whereas two-and three-rings were dominated in the water and the gill. This finding revealed a negative eco-risk effects occasionally occur in this area. The higher presence of low condensate ring structures reflected a predominant origin of petrogenic and some cases of pyrolitic sources.

  20. Occurrence and distribution of perfluoroalkyl acids (PFAAs) in surface water and sediment of a tropical coastal area (Bay of Bengal coast, Bangladesh).

    Science.gov (United States)

    Habibullah-Al-Mamun, Md; Ahmed, Md Kawser; Raknuzzaman, Mohammad; Islam, Md Saiful; Negishi, Junya; Nakamichi, Shihori; Sekine, Makoto; Tokumura, Masahiro; Masunaga, Shigeki

    2016-11-15

    This study reports the first evidence of perfluoroalkyl acids (PFAAs) in surface waters and sediments collected from the coastal area of Bangladesh. Fifteen target PFAAs, including C4-14-PFCAs (perfluoroalkyl carboxylates) and C4, C6, C8, and C10-PFSAs (perfluoroalkyl sulfonates), were quantified by HPLC-MS/MS. The ΣPFAAs in surface water and sediment samples were in the range of 10.6 to 46.8ng/L and 1.07 to 8.15ng/gdw, respectively. PFOA in water (3.17-27.8ng/L) and PFOS in sediment samples (0.60-1.14ng/gdw) were found to be the most abundant PFAAs, and these concentrations were comparable to or less than most other reported values, particularly those recorded from the coastal areas of China, Japan, Korea and Spain. The majority of the monitored PFAAs did not show clear seasonal variation. The southeastern part (Cox's Bazar and Chittagong) of the Bangladeshi coastal area was more contaminated with PFAAs than the southern (Meghna Estuary) and southwestern parts (Sundarbans). Industrial and municipal wastewater effluents, ship breaking and port activities were identified as potential sources of the PFAA contamination in this region. Field-based sediment water distribution coefficients (KD) were calculated and corrected for organic carbon content (KOC), which reduced the variability between samples. The values of log KD (1.63-2.88) and log KOC (4.02-5.16) were higher than previously reported values, which may indicate that the partitioning of PFAAs in a tropical coastal ecosystem is different from other ecosystems, such as temperate and sub-tropical regions. Although a preliminary environmental hazard assessment indicated that PFOA or PFOS levels do not currently exceed the acute safety thresholds, we should keep in mind that they are bioavailable and can accumulate in the food chain. Therefore, the ubiquity of PFAAs in the coastal area of Bangladesh warrants further studies characterizing their specific sources and the potential long-term risks they present to both

  1. Enhanced terrestrial carbon preservation promoted by reactive iron in deltaic sediments

    Science.gov (United States)

    Shields, Michael R.; Bianchi, Thomas S.; Gélinas, Yves; Allison, Mead A.; Twilley, Robert R.

    2016-02-01

    We examined the role of reactive iron (FeR) in preserving organic carbon (OC) across a subaerial chronosequence of the Wax Lake Delta, a prograding delta within the Mississippi River Delta complex. We found that ~15.0% of the OC was bound to FeR, and the dominant binding mechanisms varied from adsorption in the youngest subaerial region to coprecipitation at the older, vegetated sites. The δ13C of the iron-associated OC was more negative than the total OC (mean = -2.6‰), indicating greater preference for terrestrial material and/or compounds with more negative δ13C values. However, only the adsorbed OC displayed preferential binding of lignin phenols. We estimate that ~8% of the OC initially deposited in deltaic systems is bound to FeR (equivalent to 6 × 1012 gC yr-1), and this percentage increases postdepositionally, as coprecipitation of FeR and OC allows for an even greater amount of OC to be bound to FeR.

  2. A Semi-Analytic Model for Estimating Total Suspended Sediment Concentration in Turbid Coastal Waters of Northern Western Australia Using MODIS-Aqua 250 m Data

    Directory of Open Access Journals (Sweden)

    Passang Dorji

    2016-06-01

    Full Text Available Knowledge of the concentration of total suspended sediment (TSS in coastal waters is of significance to marine environmental monitoring agencies to determine the turbidity of water that serve as a proxy to estimate the availability of light at depth for benthic habitats. TSS models applicable to data collected by satellite sensors can be used to determine TSS with reasonable accuracy and of adequate spatial and temporal resolution to be of use for coastal water quality monitoring. Thus, a study is presented here where we develop a semi-analytic sediment model (SASM applicable to any sensor with red and near infrared (NIR bands. The calibration and validation of the SASM using bootstrap and cross-validation methods showed that the SASM applied to Moderate Resolution Imaging Spectroradiometer (MODIS-Aqua band 1 data retrieved TSS with a root mean square error (RMSE and mean averaged relative error (MARE of 5.75 mg/L and 33.33% respectively. The application of the SASM over our study region using MODIS-Aqua band 1 data showed that the SASM can be used to monitor the on-going, post and pre-dredging activities and identify daily TSS anomalies that are caused by natural and anthropogenic processes in coastal waters of northern Western Australia.

  3. Iron oxide reduction in methane-rich deep Baltic Sea sediments

    DEFF Research Database (Denmark)

    Egger, Matthias; Hagens, Mathilde; Sapart, Celia J.

    2017-01-01

    /L transition. Our results reveal a complex interplay between production, oxidation and transport of methane showing that besides organoclastic Fe reduction, oxidation of downward migrating methane with Fe oxides may also explain the elevated concentrations of dissolved ferrous Fe in deep Baltic Sea sediments...... profiles and numerical modeling, we propose that a potential coupling between Fe oxide reduction and methane oxidation likely affects deep Fe cycling and related biogeochemical processes, such as burial of phosphorus, in systems subject to changes in organic matter loading or bottom water salinity....

  4. Microbial production of isotopically light iron(II) in a modern chemically precipitated sediment and implications for isotopic variations in ancient rocks

    Science.gov (United States)

    Tangalos, G.E.; Beard, B.L.; Johnson, C.M.; Alpers, Charles N.; Shelobolina, E.S.; Xu, H.; Konishi, H.; Roden, E.E.

    2012-01-01

    The inventories and Fe isotope composition of aqueous Fe(II) and solid-phase Fe compounds were quantified in neutral-pH, chemically precipitated sediments downstream of the Iron Mountain acid mine drainage site in northern California, USA. The sediments contain high concentrations of amorphous Fe(III) oxyhydroxides [Fe(III)am] that allow dissimilatory iron reduction (DIR) to predominate over Fe–S interactions in Fe redox transformation, as indicated by the very low abundance of Cr(II)-extractable reduced inorganic sulfur compared with dilute HCl-extractable Fe. δ56Fe values for bulk HCl- and HF-extractable Fe were ≈ 0. These near-zero bulk δ56Fe values, together with the very low abundance of dissolved Fe in the overlying water column, suggest that the pyrite Fe source had near-zero δ56Fe values, and that complete oxidation of Fe(II) took place prior to deposition of the Fe(III) oxide-rich sediment. Sediment core analyses and incubation experiments demonstrated the production of millimolar quantities of isotopically light (δ56Fe ≈ -1.5 to -0.5‰) aqueous Fe(II) coupled to partial reduction of Fe(III)am by DIR. Trends in the Fe isotope composition of solid-associated Fe(II) and residual Fe(III)am are consistent with experiments with synthetic Fe(III) oxides, and collectively suggest an equilibrium Fe isotope fractionation between aqueous Fe(II) and Fe(III)am of approximately -2‰. These Fe(III) oxide-rich sediments provide a model for early diagenetic processes that are likely to have taken place in Archean and Paleoproterozoic marine sediments that served as precursors for banded iron formations. Our results suggest pathways whereby DIR could have led to the formation of large quantities of low-δ56Fe minerals during BIF genesis.

  5. Comparative analysis of bacterial community-metagenomics in coastal Gulf of Mexico sediment microcosms following exposure to Macondo oil (MC252)

    KAUST Repository

    Koo, Hyunmin

    2014-09-10

    The indigenous bacterial communities in sediment microcosms from Dauphin Island (DI), Petit Bois Island (PB) and Perdido Pass (PP) of the coastal Gulf of Mexico were compared following treatment with Macondo oil (MC252) using pyrosequencing and culture-based approaches. After quality-based trimming, 28,991 partial 16S rRNA sequence reads were analyzed by rarefaction, confirming that analyses of bacterial communities were saturated with respect to species diversity. Changes in the relative abundances of Proteobacteria, Bacteroidetes and Firmicutes played an important role in structuring bacterial communities in oil-treated sediments. Proteobacteria were dominant in oil-treated samples, whereas Firmicutes and Bacteroidetes were either the second or the third most abundant taxa. Tenericutes, members of which are known for oil biodegradation, were detected shortly after treatment, and continued to increase in DI and PP sediments. Multivariate statistical analyses (ADONIS) revealed significant dissimilarity of bacterial communities between oil-treated and untreated samples and among locations. In addition, a similarity percentage analysis showed the contribution of each species to the contrast between untreated and oil-treated samples. PCR amplification using DNA from pure cultures of Exiguobacterium,  Pseudoalteromonas,  Halomonas and Dyadobacter, isolated from oil-treated microcosm sediments, produced amplicons similar to polycyclic aromatic hydrocarbon-degrading genes. In the context of the 2010 Macondo blowout, the results from our study demonstrated that the indigenous bacterial communities in coastal Gulf of Mexico sediment microcosms responded to the MC252 oil with altered community structure and species composition. The rapid proliferation of hydrocarbonoclastic bacteria suggests their involvement in the degradation of the spilt oil in the Gulf of Mexico ecosystem.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  8. Quantitative, molecular and growth analyses of Ulva microscopic propagules in the coastal sediment of Jiangsu province where green tides initially occurred.

    Science.gov (United States)

    Liu, Feng; Pang, Shao Jun; Zhao, Xiao Bo; Hu, Chuan Ming

    2012-03-01

    From 2007 to 2011, large-scale green tides formed by unattached filamentous alga, Ulva prolifera in Ulva linza-procera-prolifera complex, have initially occurred in Jiangsu coasts of China. The real niche or the substrate(s) on which U. prolifera attaches before it starts to float is still under debate. However, great numbers of Ulva propagules would be supposed to exist in the microscopic, overwintering stage for the next spring's bloom in coastal environments. This study was designed to confirm the above prediction and investigate abundance, species composition and growth characteristics of Ulva propagules in the sediments. Quantification result showed that Ulva propagules widely distributed in the sediments and the abundance of these isolates did not change much over a 3-month testing period at low temperature in darkness. Molecular data based on three DNA markers revealed that four Ulva species existed in the sediments, among which green-tide forming alga, U. prolifera, was included. Elevated levels of temperature, irradiance as well as nutrients in seawater greatly facilitated recovery and growth of propagules. Results of this investigation indicated the possibility of microscopic propagules turning directly into floating biomass in season when temperature, irradiance and nutrients together meet the required levels in questioned coastal water area. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. Coastal resuspension

    International Nuclear Information System (INIS)

    Garland, J.A.

    1991-11-01

    There are several potential mechanisms for the suspension in air of radioactive or other pollutants from coastal sea water, beaches, mud banks and salt marshes. Available measurements rarely allow these mechanisms to be distinguished. The limited data show a broad spread of results. When normalised by the concentration of radionuclides in beach sediments most of the data indicate concentrations equivalent to 1 to 30 μg m -3 of sediment suspended in air, both for sampling sites on open coasts and near estuaries. Limited evidence for sampling sites located on salt marshes indicates about 0.2 μg m -3 of suspended sediment. These values represent the aggregate effect of the mechanisms that operate at a limited number of coastal locations. At other locations it is possible that additional mechanisms will contribute to the suspension of sediment. (Author)

  10. Spatial and temporal distribution of tributyltin (TBT) in seawater, sediments and bivalves from coastal areas of Korea during 2001-2005.

    Science.gov (United States)

    Choi, Minkyu; Choi, Hee-Gu; Moon, Hyo-Bang; Kim, Gui-Young

    2009-04-01

    Tributyltin (TBT) concentrations were determined in seawater, sediments and bivalve samples collected from Korean coastal areas during 2001-2005, to investigate the levels and temporal variation in TBT contamination in relation to the timing of the imposition of regulations on TBT use in Korea. TBT concentrations ranged from TBT were found at locations close to intensive shipping traffic and industrial complexes, and the contamination at some hot spot areas was high enough to cause harmful effects on marine organisms. TBT concentrations and their occurrence in Korean coastal waters have been decreasing annually. In particular, TBT concentrations in seawater have dramatically decreased. This result is consistent with regulations and bans on the use of TBT in Korea.

  11. Lithogenic and biogenic particle deposition in an Antarctic coastal environment (Marian Cove, King George Island): Seasonal patterns from a sediment trap study

    Science.gov (United States)

    Khim, B. K.; Shim, J.; Yoon, H. I.; Kang, Y. C.; Jang, Y. H.

    2007-06-01

    Particulate suspended material was recovered over a 23-month period using two sediment traps deployed in shallow water (˜30 m deep) off the King Sejong Station located in Marian Cove of King George Island, West Antarctica. Variability in seasonal flux and geochemical characteristics of the sediment particles highlights seasonal patterns of sedimentation of both lithogenic (terrigenous) and biogenic particles in the coastal glaciomarine environment. All components including total mass flux, lithogenic particle flux and biogenic particle flux show distinct seasonal variation, with high recovery rates during the summer and low rates under winter fast ice. The major contributor to total mass flux is the lithogenic component, comprising from 88% during the summer months (about 21 g m -2 d -1) up to 97% during the winter season (about 2 g m -2 d -1). The lithogenic particle flux depends mainly on the amount of snow-melt (snow accumulation) delivered into the coastal region as well as on the resuspension of sedimentary materials. These fine-grained lithogenic particles are silt-to-clay sized, composed mostly of clay minerals weathered on King George Island. Biogeni