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Sample records for estuarine sediment communities

  1. Linking pollution induced community tolerance (PICT) and microbial community structure in chronically metal polluted estuarine sediments.

    PubMed

    Ogilvie, Lesley A; Grant, Alistair

    2008-03-01

    We tested the ability of pollution induced community tolerance (PICT) to detect the effects of chronic metal pollution on estuarine sediment microbial communities, along a gradient spanning two orders of magnitude in metal concentrations. In tandem, we investigated the associated microbial community structure using terminal restriction fragment length polymorphism (T-RFLP). Tolerance of microbes to Cu, measured as IC50 (inhibitory concentration 50%), was strongly correlated with pore water Cu concentration (r(2)=0.842). No strong correlation existed for other metals tested, highlighting the ability of PICT to identify the pollutant causing a toxic effect. There was no correlation between microbial community structure and community tolerance to metals tested, but analysis of community structure did provide some information on reasons for observed PICT response. PICT methodology used here provided a greater strength and consistency of association with pollutant concentration compared to microbial community structure and can be recommended as a sensitive indicator of metal pollution on estuarine sediment microbial communities.

  2. Cross-habitat impacts of species decline: response of estuarine sediment communities to changing detrital resources.

    PubMed

    Bishop, Melanie Jane; Coleman, Melinda A; Kelaher, Brendan P

    2010-06-01

    Food webs of many ecosystems are sustained by organic matter from other habitats. Human activities and climatic change are increasingly modifying the quality and supply of these resources, yet for most ecosystems it is unknown how the taxonomic composition of organic matter influences community composition. Along the coastline of Sydney, Australia, the once abundant habitat-forming macroalga, Phyllospora comosa, is now locally extinct. Shallow reefs are now primarily occupied by Sargassum sp. and, to a lesser extent, the kelp Ecklonia radiata. We experimentally manipulated the supply of P. comosa, Sargassum sp. and E. radiata to estuarine sediments to assess responses by macroinvertebrate communities to: (1) changing the identity of the dominant detrital resource; and (2) varying the ratio of input of different macrophytes. Estuarine sediments dosed with P. comosa supported greater abundances of macroinvertebrates than sediments receiving Sargassum sp. or the kelp E. radiata. Whereas plots receiving Sargassum sp. or E. radiata had fewer macroinvertebrates than controls, plots receiving a moderate (120 g dry weight per m(2)) loading of P. comosa had more. Mixtures of detritus dominated by P. comosa supported similar macroinvertebrate communities to monocultures of the alga. Communities in sediments receiving detritus comprised of less than one-third P. comosa were, however, distinctly different. Our study provides evidence that the ecological ramifications of species decline can extend to spatially removed ecosystems, subsidized by allochthonous materials. Even prior to extinction of detrital sources, small changes in their provision of organic matter may alter the structure of subsidized communities.

  3. Organic Matter Loading Modifies the Microbial Community Responsible for Nitrogen Loss in Estuarine Sediments.

    PubMed

    Babbin, Andrew R; Jayakumar, Amal; Ward, Bess B

    2016-04-01

    Coastal marine sediments, as locations of substantial fixed nitrogen loss, are very important to the nitrogen budget and to the primary productivity of the oceans. Coastal sediment systems are also highly dynamic and subject to periodic natural and anthropogenic organic substrate additions. The response to organic matter by the microbial community involved in nitrogen loss processes was evaluated using mesocosms of Chesapeake Bay sediments. Over the course of a 50-day incubation, rates of anammox and denitrification were measured weekly using (15)N tracer incubations, and samples were collected for genetic analysis. Rates of both nitrogen loss processes and gene abundances associated with them corresponded loosely, probably because heterogeneities in sediments obscured a clear relationship. The rates of denitrification were stimulated more, and the fraction of nitrogen loss attributed to anammox slightly reduced, by the higher organic matter addition. Furthermore, the large organic matter pulse drove a significant and rapid shift in the denitrifier community composition as determined using a nirS microarray, indicating that the diversity of these organisms plays an essential role in responding to anthropogenic inputs. We also suggest that the proportion of nitrogen loss due to anammox in these coastal estuarine sediments may be underestimated due to temporal dynamics as well as from methodological artifacts related to conventional sediment slurry incubation approaches.

  4. High Levels of Sediment Contamination Have Little Influence on Estuarine Beach Fish Communities

    PubMed Central

    McKinley, Andrew C.; Dafforn, Katherine A.; Taylor, Matthew D.; Johnston, Emma L.

    2011-01-01

    While contaminants are predicted to have measurable impacts on fish assemblages, studies have rarely assessed this potential in the context of natural variability in physico-chemical conditions within and between estuaries. We investigated links between the distribution of sediment contamination (metals and PAHs), physico-chemical variables (pH, salinity, temperature, turbidity) and beach fish assemblages in estuarine environments. Fish communities were sampled using a beach seine within the inner and outer zones of six estuaries that were either heavily modified or relatively unmodified by urbanization and industrial activity. All sampling was replicated over two years with two periods sampled each year. Shannon diversity, biomass and abundance were all significantly higher in the inner zone of estuaries while fish were larger on average in the outer zone. Strong differences in community composition were also detected between the inner and outer zones. Few differences were detected between fish assemblages in heavily modified versus relatively unmodified estuaries despite high concentrations of sediment contaminants in the inner zones of modified estuaries that exceeded recognized sediment quality guidelines. Trends in species distributions, community composition, abundance, Shannon diversity, and average fish weight were strongly correlated to physico-chemical variables and showed a weaker relationship to sediment metal contamination. Sediment PAH concentrations were not significantly related to the fish assemblage. These findings suggest that variation in some physico-chemical factors (salinity, temperature, pH) or variables that co-vary with these factors (e.g., wave activity or grain size) have a much greater influence on this fish assemblage than anthropogenic stressors such as contamination. PMID:22039470

  5. Metagenomic Insights into Effects of Chemical Pollutants on Microbial Community Composition and Function in Estuarine Sediments Receiving Polluted River Water.

    PubMed

    Lu, Xiao-Ming; Chen, Chang; Zheng, Tian-Ling

    2017-05-01

    Pyrosequencing and metagenomic profiling were used to assess the phylogenetic and functional characteristics of microbial communities residing in sediments collected from the estuaries of Rivers Oujiang (OS) and Jiaojiang (JS) in the western region of the East China Sea. Another sediment sample was obtained from near the shore far from estuaries, used for contrast (CS). Characterization of estuary sediment bacterial communities showed that toxic chemicals potentially reduced the natural variability in microbial communities, while they increased the microbial metabolic enzymes and pathways. Polycyclic aromatic hydrocarbons (PAHs) and nitrobenzene were negatively correlated with the bacterial community variation. The dominant class in the sediments was Gammaproteobacteria. According to Kyoto Encyclopedia of Genes and Genomes (KEGG) enzyme profiles, dominant enzymes were found in estuarine sediments, which increased greatly, such as 2-oxoglutarate synthase, acetolactate synthase, inorganic diphosphatase, and aconitate hydratase. In KEGG pathway profiles, most of the pathways were also dominated by specific metabolism in these sediments and showed a marked increase, for instance alanine, aspartate, and glutamate metabolism, carbon fixation pathways in prokaryotes, and aminoacyl-tRNA biosynthesis. The estuarine sediment bacterial diversity varied with the polluted river water inputs. In the estuary receiving river water from the more seriously polluted River Oujiang, the sediment bacterial community function was more severely affected.

  6. 34S/ 32S fractionation by sulfate-reducing microbial communities in estuarine sediments

    NASA Astrophysics Data System (ADS)

    Stam, Marjolijn C.; Mason, Paul R. D.; Laverman, Anniet M.; Pallud, Céline; van Cappellen, Philippe

    2011-07-01

    Sulfur isotope fractionation during microbial sulfate reduction in brackish estuarine sediments was studied using an experimental flow-through reactor approach designed to preserve the in situ physical, geochemical and microbial structure of the sediment. Concurrent measurements of potential sulfate reduction rates and 34S/ 32S fractionations were carried out using intact sediment slices (2 cm thick, 4.2 cm diameter) from unvegetated, intertidal sites adjoining a salt marsh along the Scheldt estuary, The Netherlands. A total of 30 reactor experiments were performed with sediments collected in February, May and October 2006. The effects of incubation temperature (10, 20, 30 and 50 °C) and sediment depth (0-2, 4-6 and 8-10 cm) were investigated. Sulfate was supplied in non-limiting concentrations via the reactor inflow solutions; no external electron donor was supplied. Isotope fractionations ( ɛ values) were calculated from the measured differences in sulfate δ 34S between in- and outflow solutions of the reactors, under quasi-steady state conditions. Potential sulfate reduction rates (SRR) varied over one order of magnitude (5-49 nmol cm -3 h -1) and were highest in the 30 °C incubations. They decreased systematically with depth, and were highest in the sediments collected closest to the vegetated marsh. Isotope fractionations ranged from 9‰ to 34‰ and correlated inversely with SRR, as predicted by the standard fractionation model for enzymatic sulfate reduction of Rees (1973). The ɛ versus SRR relationship, however, varied between sampling times, with higher ɛ values measured in February, at comparable SRRs, than in May and October. The observed ɛ versus SRR relationships also deviated from the previously reported inverse trend for sediments collected in a marine lagoon in Denmark ( Canfield, 2001b). Thus, isotope fractionation during sulfate reduction is not uniquely determined by SRR, but is site- and time-dependent. Factors that may affect the

  7. Genetic Diversity of Benzoyl Coenzyme A Reductase Genes Detected in Denitrifying Isolates and Estuarine Sediment Communities

    PubMed Central

    Song, Bongkeun; Ward, Bess B.

    2005-01-01

    Benzoyl coenzyme A (benzoyl-CoA) reductase is a central enzyme in the anaerobic degradation of organic carbon, which utilizes a common intermediate (benzoyl-CoA) in the metabolism of many aromatic compounds. The diversity of benzoyl-CoA reductase genes in denitrifying bacterial isolates capable of degrading aromatic compounds and in river and estuarine sediment samples from the Arthur Kill in New Jersey and the Chesapeake Bay in Maryland was investigated. Degenerate primers were developed from the known benzoyl-CoA reductase genes from Thauera aromatica, Rhodopseudomonas palustris, and Azoarcus evansii. PCR amplification detected benzoyl-CoA reductase genes in the denitrifying isolates belonging to α-, β-, or γ-Proteobacteria as well as in the sediment samples. Phylogenetic analysis, sequence similarity comparison, and conserved indel determination grouped the new sequences into either the bcr type (found in T. aromatica and R. palustris) or the bzd type (found in A. evansii). All the Thauera strains and the isolates from the genera Acidovorax, Bradyrhizobium, Paracoccus, Ensifer, and Pseudomonas had bcr-type benzoyl-CoA reductases with amino acid sequence similarities of more than 97%. The genes detected from Azarocus strains were assigned to the bzd type. A total of 50 environmental clones were detected from denitrifying consortium and sediment samples, and 28 clones were assigned to either the bcr or the bzd type of benzoyl-CoA reductase genes. Thus, we could determine the genetic capabilities for anaerobic degradation of aromatic compounds in sediment communities of the Chesapeake Bay and the Arthur Kill on the basis of the detection of two types of benzoyl-CoA reductase genes. The detected genes have future applications as genetic markers to monitor aromatic compound degradation in natural and engineered ecosystems. PMID:15812036

  8. Preservation of Estuarine Sediments for Lipid Analysis of Biomass and Community Structure of Microbiota

    PubMed Central

    Federle, Thomas W.; White, David C.

    1982-01-01

    Various methods were tested for preserving estuarine sediments in the field before biochemical analysis of the microbiota. Total microbial biomass was determined as lipid phosphate (LP), and the fatty acids of the microbial lipids were used as indicators of community structure. Control samples were sieved to remove macroinvertebrates and plant materials and were extracted immediately in the field. Other samples were preserved both before and after sieving and stored for 5 days before analysis. Freezing resulted in a 50% decline in LP and significant decreases in many fatty acids. Refrigeration resulted in a 19% decrease in LP but no change in the fatty acids. Samples preserved with Formalin before sieving exhibited no significant change in LP but substantial increases in many fatty acids, which were probably derived from the macroinvertebrates. Sieved samples preserved with Formalin showed a 17 to 18% decline in LP but no change in the fatty acids. Ideally, samples should be sieved and extracted immediately in the field. However, short-term refrigeration and longer-term preservation of sieved samples with Formalin may be acceptable compromises. PMID:16346134

  9. PHYTOASSESSMENT OF ESTUARINE SEDIMENTS

    EPA Science Inventory

    Most sediment quality assessments and quality guidelines are based on the laboratory response of single animal species and benthic animal community composition. The role of plants in this hazard assessment process is poorly understood despite the fact that plant-dominated habitat...

  10. PHYTOASSESSMENT OF ESTUARINE SEDIMENTS

    EPA Science Inventory

    Most sediment quality assessments and quality guidelines are based on the laboratory response of single animal species and benthic animal community composition. The role of plants in this hazard assessment process is poorly understood despite the fact that plant-dominated habitat...

  11. Archaeal community diversity and abundance changes along a natural salinity gradient in estuarine sediments.

    PubMed

    Webster, Gordon; O'Sullivan, Louise A; Meng, Yiyu; Williams, Angharad S; Sass, Andrea M; Watkins, Andrew J; Parkes, R John; Weightman, Andrew J

    2015-02-01

    Archaea are widespread in marine sediments, but their occurrence and relationship with natural salinity gradients in estuarine sediments is not well understood. This study investigated the abundance and diversity of Archaea in sediments at three sites [Brightlingsea (BR), Alresford (AR) and Hythe (HY)] along the Colne Estuary, using quantitative real-time PCR (qPCR) of 16S rRNA genes, DNA hybridization, Archaea 16S rRNA and mcrA gene phylogenetic analyses. Total archaeal 16S rRNA abundance in sediments were higher in the low-salinity brackish sediments from HY (2-8 × 10(7) 16S rRNA gene copies cm(-3)) than the high-salinity marine sites from BR and AR (2 × 10(4)-2 × 10(7) and 4 × 10(6)-2 × 10(7) 16S rRNA gene copies cm(-3), respectively), although as a proportion of the total prokaryotes Archaea were higher at BR than at AR or HY. Phylogenetic analysis showed that members of the 'Bathyarchaeota' (MCG), Thaumarchaeota and methanogenic Euryarchaeota were the dominant groups of Archaea. The composition of Thaumarchaeota varied with salinity, as only 'marine' group I.1a was present in marine sediments (BR). Methanogen 16S rRNA genes from low-salinity sediments at HY were dominated by acetotrophic Methanosaeta and putatively hydrogentrophic Methanomicrobiales, whereas the marine site (BR) was dominated by mcrA genes belonging to methylotrophic Methanococcoides, versatile Methanosarcina and methanotrophic ANME-2a. Overall, the results indicate that salinity and associated factors play a role in controlling diversity and distribution of Archaea in estuarine sediments.

  12. Effects of sedimentary sulfide on community structure, population dynamics, and colonization depth of macrozoobenthos in organic-rich estuarine sediments.

    PubMed

    Kanaya, Gen; Uehara, Tadayasu; Kikuchi, Eisuke

    2016-08-15

    An annual field survey and in situ recolonization experiment revealed the effects of sedimentary sulfide (H2S) on macrozoobenthos in a eutrophic brackish lagoon. Species diversity was much lower throughout the year in muddy opportunist-dominant sulfidic areas. Mass mortality occurred during warmer months under elevated H2S levels. An enclosure experiment demonstrated that sedimentary H2S modified community composition, size structure, and colonization depth of macrozoobenthos. Species-specific responses to each sediment type (sand, sulfidic mud, and mud with H2S removed) resulted in changes in the established community structure. Dominant polychaetes (Hediste spp., Pseudopolydora spp., and Capitella teleta) occurred predominantly in a thin surface layer in the presence of H2S. On the other hand, organic-rich mud facilitated settlement of polychaete larvae if it does not contain H2S. These results demonstrate that sediment characteristics, including H2S level and organic content, were key structuring factors for the macrozoobenthic assemblage in organically polluted estuarine sediments.

  13. Measuring the acute toxicity of estuarine sediments

    SciTech Connect

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

    1989-01-01

    Estuarine sediments frequently are repositories and sources of anthropogenic contaminants. Toxicity is one method of assessing the environmental quality of sediments, yet because of the extreme range of salinities that characterize estuaries few infaunal organisms have both the physiological tolerance and sensitivity to chemical contaminants to serve in estuarine sediment toxicity tests. The study describes research on the estuarine burrowing amphipod, Eohaustorius estuarius Bosworth, 1973, whose survival was >95% in control sediments across a 2 to 28% salinity range over 10-d periods. E. estuarius also was acutely sensitive to low sediment concentrations of the polycyclic aromatic hydrocarbon, fluoranthene (LC50 approximately = 10.6 mg/kg), and its sensitivity to fluoranthene was not affected by salinity. E. estuarius was almost as sensitive as Rhepoxynius abronius to fluoranthene and to field-collected sediments from Puget Sound urban and industrial bays. E. estuarius was also more tolerant of very fine, uncontaminated sediments than R. abronius. Furthermore, E. estuarius was more sensitive to sediments spiked with fluoranthene than the freshwater amphipod, Hyalella azteca. E. estuarius, and possibly other estuarine haustoriid species, appears to be an excellent candidate for testing the acute toxicity if estuarine and marine sediments.

  14. Quantitative determination of microbial activity and community nutritional status in estuarine sediments: evidence for a disturbance artifact

    NASA Technical Reports Server (NTRS)

    Findlay, R. H.; Pollard, P. C.; Moriarty, D. J.; White, D. C.

    1985-01-01

    In estuarine sediments with a high degree of vertical heterogeneity in reduced substrate and terminal electron acceptor concentrations, the method of exposure of the microbiota to labeled substrates can introduce a "disturbance artifact" into measures of metabolic activity. The detection of this artifact is based on quantitative measurement of the relative rates of incorporation of [14C]acetate into phospholipid fatty acids (PLFA) and endogenous storage lipid, poly-beta-hydroxyalkanoate (PHA). Previous studies have shown that PLFA synthesis measures cellular growth and that PHA synthesis measures carbon accumulation (unbalanced growth). The "disturbance artifact" of exposure to [14C]acetate was demonstrated by comparing injection of a core with the usual or pore-water replacement or slurry techniques. Only injection of labeled substrate allowed detection of preassay disturbance of the sediment with a garden rake. The raking increased PLFA synthesis with little effect to differences in concentration or distribution of [14C]acetate in the 10-min incubation. Bioturbation induced by sand dollar feeding in estuarine sediment could be detected in an increased PLFA/PHA ratio which was due to decreased PHA synthesis if the addition of labeled substrate was by the injection technique. Addition of labeled precursors to sediment by slurry or pore-water replacement induces greater disturbance artifacts than injection techniques.

  15. Quantitative determination of microbial activity and community nutritional status in estuarine sediments: evidence for a disturbance artifact

    NASA Technical Reports Server (NTRS)

    Findlay, R. H.; Pollard, P. C.; Moriarty, D. J.; White, D. C.

    1985-01-01

    In estuarine sediments with a high degree of vertical heterogeneity in reduced substrate and terminal electron acceptor concentrations, the method of exposure of the microbiota to labeled substrates can introduce a "disturbance artifact" into measures of metabolic activity. The detection of this artifact is based on quantitative measurement of the relative rates of incorporation of [14C]acetate into phospholipid fatty acids (PLFA) and endogenous storage lipid, poly-beta-hydroxyalkanoate (PHA). Previous studies have shown that PLFA synthesis measures cellular growth and that PHA synthesis measures carbon accumulation (unbalanced growth). The "disturbance artifact" of exposure to [14C]acetate was demonstrated by comparing injection of a core with the usual or pore-water replacement or slurry techniques. Only injection of labeled substrate allowed detection of preassay disturbance of the sediment with a garden rake. The raking increased PLFA synthesis with little effect to differences in concentration or distribution of [14C]acetate in the 10-min incubation. Bioturbation induced by sand dollar feeding in estuarine sediment could be detected in an increased PLFA/PHA ratio which was due to decreased PHA synthesis if the addition of labeled substrate was by the injection technique. Addition of labeled precursors to sediment by slurry or pore-water replacement induces greater disturbance artifacts than injection techniques.

  16. Sediment diatom species and community response to nitrogen addition in Oregon (USA) estuarine tidal wetlands

    EPA Science Inventory

    Sediment microalgae play an important role in nutrient cycling and are important primary producers in the food web in Pacific Northwest estuaries. This study examines the effects of nitrogen addition to benthic microalgae in tidal wetlands of Yaquina Bay estuary on the Oregon c...

  17. Sediment diatom species and community response to nitrogen addition in Oregon (USA) estuarine tidal wetlands

    EPA Science Inventory

    Sediment microalgae play an important role in nutrient cycling and are important primary producers in the food web in Pacific Northwest estuaries. This study examines the effects of nitrogen addition to benthic microalgae in tidal wetlands of Yaquina Bay estuary on the Oregon c...

  18. Structural dynamics of microbial communities in polycyclic aromatic hydrocarbon-contaminated tropical estuarine sediments undergoing simulated aerobic biotreatment.

    PubMed

    Obi, Chioma C; Adebusoye, Sunday A; Amund, Olukayode O; Ugoji, Esther O; Ilori, Mathew O; Hedman, Curtis J; Hickey, William J

    2017-02-11

    Coastal sediments contaminated by polycyclic aromatic hydrocarbons (PAHs) can be candidates for remediation via an approach like land farming. Land farming converts naturally anaerobic sediments to aerobic environments, and the response of microbial communities, in terms of community structure alterations and corresponding effects on biodegradative activities, is unknown. A key goal of this study was to determine if different sediments exhibited common patterns in microbial community responses that might serve as indicators of PAH biodegradation. Sediments from three stations in the Lagos Lagoon (Nigeria) were used in microcosms, which were spiked with a mixture of four PAH, then examined for PAH biodegradation and for shifts in microbial community structure by analysis of diversity in PAH degradation genes and Illumina sequencing of 16S rRNA genes. PAH biodegradation was similar in all sediments, yet each exhibited unique microbiological responses and there were no microbial indicators of PAH bioremediation common to all sediments.

  19. Sediment measurement in estuarine and coastal areas

    NASA Technical Reports Server (NTRS)

    Shelley, P. E.

    1976-01-01

    A survey of uses of estuarine and coastal areas is given. Problems associated with these uses are discussed, and data needs for intelligent management of these valuable areas are outlined. Suspended sediment measurements are seen to be one of the greatest needs. To help understand the complexity of the problem, a brief discussion of sediment mechanics is given, including sediment sources, characteristics, and transport. The impact of sediment mechanics on its direct measurement (sampling and analysis) is indicated, along with recommendations for directly obtaining representative data. Indirect measurement of suspended sediment by remote sensors is discussed both theoretically and in the light of some recent experiences. The need for an integrated, multidisciplinary program to solve the problem of quantitatively measuring suspended sediment with remote sensors is stressed, and several important considerations of such a program and benefits to be derived therefrom are briefly addressed.

  20. Biodegradation of petroleum hydrocarbons in estuarine sediments: metal influence.

    PubMed

    Almeida, Raquel; Mucha, Ana P; Teixeira, Catarina; Bordalo, Adriano A; Almeida, C Marisa R

    2013-02-01

    In this work, the potential effect of metals, such as Cd, Cu and Pb, on the biodegradation of petroleum hydrocarbons in estuarine sediments was investigated under laboratory conditions. Sandy and muddy non-vegetated sediments were collected in the Lima River estuary (NW Portugal) and spiked with crude oil and each of the metals. Spiked sediments were left in the dark under constant shaking for 15 days, after which crude oil biodegradation was evaluated. To estimate microbial abundance, total cell counts were obtained by DAPI staining and microbial community structure was characterized by ARISA. Culturable hydrocarbon degraders were determined using a modified most probable number protocol. Total petroleum hydrocarbons concentrations were analysed by Fourier Transform Infrared Spectroscopy after their extraction by sonication, and metal contents were determined by atomic absorption spectrometry. The results obtained showed that microbial communities had the potential to degrade petroleum hydrocarbons, with a maximum of 32 % degradation obtained for sandy sediments. Both crude oil and metals changed the microbial community structure, being the higher effect observed for Cu. Also, among the studied metals, only Cu displayed measurable deleterious effect on the hydrocarbons degradation process, as shown by a decrease in the hydrocarbon degrading microorganisms abundance and in the hydrocarbon degradation rates. Both degradation potential and metal influence varied with sediment characteristics probably due to differences in contaminant bioavailability, a feature that should be taken into account in developing bioremediation strategies for co-contaminated estuarine sites.

  1. Influence of estuarine sediment on virus survival under field conditions.

    PubMed

    LaBelle, R L; Gerba, C P

    1980-04-01

    The survival of poliovirus 1 (LSc) and echovirus 1 (Farouk) in estuarine water and sediment was studied in Galveston Bay, Texas. Viruses were suspended in estuarine water and sediment both in dialysis tubing and in chambers constructed with polycarbonate membrane walls. Virus inactivation rates in seawater were similar in both types of chambers. Virus adsorption to sediment greatly increased survival time. The time required to inactivate 99% (T-99) of poliovirus increased from 1.4 days in seawater alone to 6.0 days for virus adsorbed to sediment at a relatively nonpolluted site. At a more polluted site, poliovirus T-99 was increased from approximately 1 h to 4925 days by virus adsorption to sediment. This study demonstrates that under field conditions virus association with estuarine sediment acts to prolong its survival in the marine environment.

  2. Copper effects on bacterial activity of estuarine silty sediments

    NASA Astrophysics Data System (ADS)

    Almeida, Adelaide; Cunha, Ângela; Fernandes, Sandra; Sobral, Paula; Alcântara, Fernanda

    2007-07-01

    , mainly, by the great intensification of bacterial biomass production and leucine turnover rate. We conclude that the bacterial community of silty estuarine sediments seems to withstand considerable concentrations of copper at the cost of reduced bacterial organic matter degradation and of the almost halting of bacterial production. The toxic effects elicited by copper on protein and carbohydrate degradation were not rapidly repaired by erosion and oxygenation of the sediment cells but, in contrast, bacterial biomass production and leucine turnover were rapidly and efficiently reactivated.

  3. Benthic infaunal community structuring in an acidified tropical estuarine system

    PubMed Central

    2014-01-01

    Background Recent studies suggest that increasing ocean acidification (OA) should have strong direct and indirect influences on marine invertebrates. While most theory and application for OA is based on relatively physically-stable oceanic ecological systems, less is known about the effects of acidification on nearshore and estuarine systems. Here, we investigated the structuring of a benthic infaunal community in a tropical estuarine system, along a steep salinity and pH gradient, arising largely from acid-sulphate groundwater inflows (Sungai Brunei Estuary, Borneo, July 2011- June 2012). Results Preliminary data indicate that sediment pore-water salinity (range: 8.07 - 29.6 psu) declined towards the mainland in correspondence with the above-sediment estuarine water salinity (range: 3.58 – 31.2 psu), whereas the pore-water pH (range: 6.47- 7.72) was generally lower and less variable than the estuarine water pH (range: 5.78- 8.3), along the estuary. Of the thirty six species (taxa) recorded, the polychaetes Neanthes sp., Onuphis conchylega, Nereididae sp. and the amphipod Corophiidae sp., were numerically dominant. Calcified microcrustaceans (e.g., Cyclopoida sp. and Corophiidae sp.) were abundant at all stations and there was no clear distinction in distribution pattern along the estuarine between calcified and non-calcified groups. Species richness increased seawards, though abundance (density) showed no distinct directional trend. Diversity indices were generally positively correlated (Spearman’s rank correlation) with salinity and pH (p <0.05) and negatively with clay and organic matter, except for evenness values (p >0.05). Three faunistic assemblages were distinguished: (1) nereid-cyclopoid-sabellid, (2) corophiid-capitellid and (3) onuphid- nereid-capitellid. These respectively associated with lower salinity/pH and a muddy bottom, low salinity/pH and a sandy bottom, and high salinity/pH and a sandy bottom. However, CCA suggested that species distribution

  4. Arsenic pollution in Patos Lagoon estuarine sediments, Brazil.

    PubMed

    Mirlean, Nicolai; Andrus, Vlad E; Baisch, Paulo; Griep, Gilberto; Casartelli, Maria R

    2003-11-01

    Arsenic distribution in sediments of the Mirim-Patos lagoonal system is investigated. Deposits of fresh water Mirim Lagoon and those of the fresh water part of the Patos Lagoon contain 2.5 and 7.7 mg kg(-1), respectively, on average of total arsenic. In contrast, estuarine sediments of the Patos Lagoon are evidently contaminated by arsenic in high concentrations (up to 50 mg kg(-1)), and about 80% of the arsenic there is found in a bioavailable form. Analytical data coupled with direct, visual observations of estuarine water contamination by raw phosphorites and fertilizers suggest that the major source of arsenic in the estuarine sediments originated from the fertilizer industry.

  5. Role of Phragmites australis (common reed) for heavy metals phytoremediation of estuarine sediments.

    PubMed

    Cicero-Fernández, Diego; Peña-Fernández, Manuel; Expósito-Camargo, Jose A; Antizar-Ladislao, Blanca

    2016-01-01

    The ability of Phragmites australis to take up heavy metals (Co, Ni, Mo, Cd, Pb, Cr, Cu, Fe, Mn, Zn, and Hg) and other trace elements (As, Se, Ba), from estuarine sediments was investigated using a pilot plant experimental approach. Bioaccumulation (BCF) and translocation factors (TF) were calculated in vegetative and senescence periods for two populations of P. australis, from contaminated (MIC) and non-contaminated (GAL) estuarine sediments, respectively, both growing in estuarine contaminated sediment (RIA) from ría del Carmen y Boo, Santander Bay, Spain. The highest BCF values were obtained for Ni (0.43), Ba (0.43) Mo (0.36), Cr (0.35), and Cd (0.31) for plants collected from site GAL following the senescence period. The highest BCF values recorded for plants collected from MIC following the senescence period were for Mo (0.22) and Cu (0.22). Following senescence, plants collected from GAL and MIC presented TF>1 for Ni, Mo, Se, and Zn, and in addition plants collected from MIC presented TF>1 for Ba, Cr, and Mn. A substantial increase of Micedo's rhizosphere, six times higher than Galizano's rhizosphere, suggested adaptation to contaminated sediment. The evaluated communities of P. australis demonstrated their suitability for phytoremediation of heavy metals contaminated estuarine sediments.

  6. The Distribution of Thermophilic Sulfate-reducing Bacteria Along an Estuarine Gradient Reveals Multiple Origins of Endospores in Estuarine Sediments

    NASA Astrophysics Data System (ADS)

    Bell, E.

    2015-12-01

    Cold marine sediments harbour inactive spores of thermophilic bacteria. These misplaced thermophiles are genetically similar to microorganisms detected in deep biosphere environments, leading to the hypothesis that seabed fluid flow transports thermophiles out of warm subsurface environments and into the ocean. Estuaries form the transition between the marine and the terrestrial biosphere and are influenced by tidal currents, surface run-off and groundwater seepage. Endospores from thermophilic bacteria present in estuarine sediments could therefore originate from a number of sources that may influence the estuary differently. We have therefore tested the hypothesis that this will lead to a gradient in the composition of thermophilic endospore populations in estuarine sediments. The distribution of thermophilic spore-forming sulfate-reducing bacteria along an estuarine gradient from freshwater (River Tyne, UK) to marine (North Sea) was investigated. Microbial community analysis by 16S rRNA gene amplicon sequencing revealed changes in the thermophilic population enriched at different locations within the estuary. Certain species were only detected at the marine end, highlighting possible links to deep marine biosphere habitats such as oil reservoirs that harbour closely related Desulfotomaculum spp. Conversely, other taxa were predominantly observed in the freshwater reaches of the estuary indicating dispersal from an upstream or terrestrial source. Different endospore populations were enriched dependent on incubation temperature and spore heat-resistance. Microcosms incubated at 50, 60 or 70°C showed a shift in the dominant species of Desulfotomaculum enriched as the temperature increased. Microcosms triple-autoclaved at 121°C prior to incubation still showed rapid and reproducible sulfate-reduction and some Desulfotomaculum spp. remained active after autoclaving at 130°C. These results show that temperature physiology and biogeographic patterns can be used to

  7. Roles and Patterns of Hurricane Sedimentation in an Estuarine Marsh Landscape

    NASA Astrophysics Data System (ADS)

    Nyman, J. A.; Crozier, C. R.; DeLaune, R. D.

    1995-06-01

    The passage of hurricane Andrew across the Louisiana coastal zone in 1992 was used to study the effects of hurricane sedimentation on estuarine marshes. (1) The thickness and nutrient content of hurricane sediments, (2) the composition of hurricane sediments relative to pre-existing sediments, and (3) the relationship between hurricane sedimentation and small-scale heterogeneity in the emergent plant community were investigated. Vertical accretion resulting from the hurricane was 4-11 times greater than the long-term (30 year) annual rate. The hurricane sediments will be within the root zone of emergent vegetation for 35-50 years, depending on the local marsh vertical accretion rate. Element concentration, organic matter content, and texture of hurricane sediments varied over a wide area, which suggested that hurricane sediments did not originate from a common sediment pool. The concentration of most elements analysed did not differ between hurricane sediments and pre-existing sediments, which suggested that hurricane sediments originated primarily from the same local bays and lakes that provide material for other sedimentation events. Hurricane sediments were thicker in Juncus roemerianusstands than in surrounding Spartina alterniflorastands. Greater hurricane sedimentation in J. roemerianusstands was attributed to greater stem density there and may help maintain plant community heterogeneity if J. roemerianusis less flood-tolerant than S. alterniflora, as previous work suggests. Previous studies have noted the effect of environmental gradients on plant species distribution, but our data indicate that plant species can also generate different environmental conditions associated with their distribution.

  8. Methylmercury production in estuarine sediments: role of organic matter

    PubMed Central

    Schartup, Amina T.; Mason, Robert P.; Balcom, Prentiss H.; Hollweg, Terill A.; Chen, Celia Y.

    2013-01-01

    Methylmercury (MeHg) affects wildlife and human health mainly through marine fish consumption. In marine systems, MeHg is formed from inorganic mercury (HgII) species primarily in sediments then accumulates and biomagnifies in the food web. Most of the fish consumed in the US are from estuarine and marine systems highlighting the importance of understanding MeHg formation in these productive regions. Sediment organic matter has been shown to limit mercury methylation in estuarine ecosystems, as a result it is often described as the primary control over MeHg production. In this paper, we explore the role of organic matter by looking at the effects of its changing sediment concentrations on the methylation rates across multiple estuaries. We measured sedimentary MeHg production at eleven estuarine sites that were selected for their contrasting biogeochemical characteristics, mercury (Hg) content, and location in the Northeastern US (ME, NH, CT, NY, and NJ). Sedimentary total Hg concentrations ranged across five orders of magnitude, increasing in concentration from the pristine, sandy sediments of Wells (ME), to industrially contaminated areas like Portsmouth (NH) and Hackensack (NJ). We find that methylation rates are the highest at locations with high Hg content (relative to carbon), and that organic matter does not hinder mercury methylation in estuaries. PMID:23194318

  9. A manipulative field experiment to evaluate an integrative methodology for assessing sediment pollution in estuarine ecosystems.

    PubMed

    Sanz-Lázaro, Carlos; Marín, Arnaldo

    2009-05-15

    The assessment of sediment contamination is of crucial importance for the management of estuarine ecosystems. Environmental risk assessment of oil pollution must be specific to these ecosystems because of their unique toxicant bioavailability dynamics, which is not comparable with that of other ecosystems where the environmental parameters are less variable. The goal of this work was to test in two European estuarine areas (Ria de Aveiro, Portugal; La Manga, Spain) whether the common methodology used to evaluate sediment pollution in marine sediment (amphipod toxicity tests and community structure analysis) is suited to these physico-chemically unique systems. Manipulative field experiments were conducted at three oil concentration levels, to compare resulting changes in community structure with laboratory and in situ amphipod toxicity tests carried out with native amphipod species Corophium multisetosum (Atlantic area) and Microdeutopus gryllotalpa (Mediterranean area). The impact of the toxicant was reflected in the community structure and toxicity tests, both of which were correlated with oil concentration. These results point to this methodology being a reliable tool for assessing and monitoring pollution in estuarine areas.

  10. Lead distribution in coastal and estuarine sediments around India.

    PubMed

    Chakraborty, Sucharita; Chakraborty, Parthasarathi; Nath, B Nagender

    2015-08-15

    This study describes the geochemical distribution of lead (Pb) and identifies the critical factors that significantly control Pb distribution and speciation in coastal and estuarine sediments around India by using published data from the literature. Crustal sources influence the abundance of Pb in coastal sediment from the south-east and central-west coast of India. Parts of north-east, north-west, and south-west coast of India were polluted by Pb. Distribution of Pb in sediments, from the north-east and north-west coasts of India, were controlled by Fe-Mn oxyhydroxide mineral phases of the sediments. However, organic carbon (OC) seemed to be a dominant factor in controlling the distribution of Pb in sediments from the central-east and south-west coasts of India. The outcome of this study may help in decision-making to predict the levels of Pb from natural and anthropogenic sources and to control Pb pollution in coastal and estuarine sediments around India. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. VARIATIONS IN THE SPECTRAL PROPERTIES OF FRESHWATER AND ESTUARINE CDOM CAUSED BY PARTITIONING ONTO RIVER AND ESTUARINE SEDIMENTS

    EPA Science Inventory

    The optical properties and geochemical cycling of chromophoric dissolved organic matter (CDOM) are altered by its sorption to freshwater and estuarine sediments. Measured partition coefficients (Kp) of Satilla River (Georgia) and Cape Fear River estuary (North Carolina) CDOM ran...

  12. VARIATIONS IN THE SPECTRAL PROPERTIES OF FRESHWATER AND ESTUARINE CDOM CAUSED BY PARTITIONING ONTO RIVER AND ESTUARINE SEDIMENTS

    EPA Science Inventory

    The optical properties and geochemical cycling of chromophoric dissolved organic matter (CDOM) are altered by its sorption to freshwater and estuarine sediments. Measured partition coefficients (Kp) of Satilla River (Georgia) and Cape Fear River estuary (North Carolina) CDOM ran...

  13. Sediment transport in a surface-advected estuarine plume

    NASA Astrophysics Data System (ADS)

    Fagherazzi, S.; Yao, H.; Leonardi, N.; Li, J.

    2016-12-01

    The interplay between suspended sediment transport and plume hydrodynamics in a surface-advected estuarine plume has been studied using a three-dimensional numerical model. The presence of fine sediments diminishes the plume-sea density anomaly, affecting the formation of the freshwater bulge and reducing the related alongshore freshwater transport. The geometry of the freshwater bulge and the sediment distribution within it are affected by sediment characteristics. In the presence of sediments having low settling velocity, the system behaves similarly to an increase in salinity of the river discharge. We introduce the ratio between the timescale it takes the sediment to travel within the bulge and the settling timescale. When <1, the suspended sediments enter the alongshore coastal current. When >1 the sediments are deposited within the bulge. Based on the simulations conducted in this paper, a critical range of settling velocity (0.07 mm/s to 0.2 mm/s) exists above which no sediment transport in the alongshore coastal current is allowed. The influence of flood duration and magnitude on the alongshore sediment flux is also explored. Results indicate that low and long-lasting flood events.

  14. Release of anthracene from estuarine sediments by crab bioturbation effects.

    PubMed

    Sun, Nan; Chen, Yanli; Ma, Lixin; Xu, Shuqin

    2017-01-01

    To investigate bioturbation effects on anthracene (Ant) release from sediments to the overlying water, indoor microcosms were developed. Naturally contaminated estuarine sediments were exposed to the crab Helice tiensinensis over 70 days and compared with sediments with no crab. Bioturbation by crab could significantly increase the release of both particulate and dissolved Ant. The releases of particulate Ant with bioturbation treatments were 2.3-11.7 times higher than in the control treatments. However, the releases of dissolved Ant with bioturbation treatments were 1.7-3.7 times higher than in the control treatments. The ratio of particulate Ant/total Ant varied from 89 % to 98 % in the bioturbation treatments, which was significantly higher than in the control treatments. These results indicate that crab bioturbation significantly enhanced both particulate and dissolved Ant release from sediment, but the particulate Ant is the predominant process.

  15. Towards Sustainable Water Quality In Estuarine Impoundments: Sediment Processes.

    NASA Astrophysics Data System (ADS)

    Wright, J.; Worrall, F.

    Several estuarine impoundment schemes have been built or are proposed in the UK and worldwide. The impounding of estuaries is currently a popular approach to urban regeneration in the UK. By creation of an aesthetically pleasing amenity impound- ment, including the drowning of "unsightly" tidal mud flats, it is hoped that prestige development will be encouraged in the estuarine area. Impounding fundamentally alters the dynamics of estuaries, with consequences in terms of sedimentation patterns and rates, and water quality. The SIMBA Project at- tempts to understand the controls on water quality in impoundments, with a view to- wards long term and sustainable high water quality through good barrage design and management practice. The results of process based studies, concentrating on interactions between sediment and water quality in the systems, are presented. A series of sequential extraction exper- iments have been carried out on cores of sediment to model the releases from sediment under different environmental conditions likely to be encountered in the impound- ments. Results are related to similar experiments carried out on suspended particulate material, and to pore-water experiments carried out using gel-probes.

  16. Pepsin-Digestibility of Contaminated Estuarine Sediments

    NASA Astrophysics Data System (ADS)

    Turner, A.; Henon, D. N.; Dale, J. L. L.

    2001-11-01

    A standard method for the in vitro digestion of animal protein feeds (2% pepsin in 0·075 N HCl) has been applied to contaminated sediments in order to evaluate a ' bioavailable ' or ' gut-soluble ' fraction of carbon, nitrogen and mineral and trace metals. For most sediment samples, considerably more nitrogen was digested than carbon because of enzymatic digestion of proteinaceous material, and the sequence of metal ' gut-solubility ' was: Cu, Zn>Mn>Fe≫Al. The principal mechanism of metal release appears to be hydrochloric acid digestion of inorganic hydrogenous host phases (e.g. amorphous Fe and Mn oxides), although release of Cu via surface complexation with pepsin molecules may also be significant, and the amount of metal digested enzymatically is restricted to a small and unquantifiable fraction associated with proteinaceous material. Dilute HCl alone does not, however, afford a suitable surrogate for assessing a gut-soluble fraction of metal because enzymatic and acid digestions exhibit synergistic effects, including possible re-adsorption of pepsin-metal complexes under acidic conditions, and exposure and acid attack of otherwise inaccessible hydrogenous material following enzymatic digestion of organic matter.

  17. Microbial Formation of Ethane in Anoxic Estuarine Sediments

    PubMed Central

    Oremland, Ronald S.

    1981-01-01

    Estuarine sediment slurries produced methane and traces of ethane when incubated under hydrogen. Formation of methane occurred over a broad temperature range with an optimum above 65°C. Ethane formation had a temperature optimum at 40°C. Formation of these two gases was inhibited by air, autoclaving, incubation at 4 and 80°C, and by the methanogenic inhibitor, 2-bromoethanesulfonic acid. Ethane production was stimulated by addition of ethylthioethanesulfonic acid, and production from ethylthioethanesulfonic acid was blocked by 2-bromoethanesulfonic acid. A highly purified enrichment culture of a methanogenic bacterium obtained from sediments produced traces of ethane from ethylthioethanesulfonic acid. These results indicate that the small quantities of ethane found in anaerobic sediments can be formed by certain methanogenic bacteria. PMID:16345805

  18. Microbial formation of ethane in anoxic estuarine sediments

    USGS Publications Warehouse

    Oremland, Ronald S.

    1981-01-01

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

  19. Anaerobic oxidation of acetylene by estuarine sediments and enrichment cultures

    USGS Publications Warehouse

    Culbertson, Charles W.; Zehnder, Alexander J. B.; Oremland, Ronald S.

    1981-01-01

    Acetylene disappeared from the gas phase of anaerobically incubated estuarine sediment slurries, and loss was accompanied by increased levels of carbon dioxide. Acetylene loss was inhibited by chloramphenicol, air, and autoclaving. Addition of 14C2H2 to slurries resulted in the formation of 14CO2 and the transient appearance of 14C-soluble intermediates, of which acetate was a major component. Acetylene oxidation stimulated sulfate reduction; however, sulfate reduction was not required for the loss of C2H2 to occur. Enrichment cultures were obtained which grew anaerobically at the expense of C2H2.

  20. Anaerobic Oxidation of Acetylene by Estuarine Sediments and Enrichment Cultures

    PubMed Central

    Culbertson, Charles W.; Zehnder, Alexander J. B.; Oremland, Ronald S.

    1981-01-01

    Acetylene disappeared from the gas phase of anaerobically incubated estuarine sediment slurries, and loss was accompanied by increased levels of carbon dioxide. Acetylene loss was inhibited by chloramphenicol, air, and autoclaving. Addition of 14C2H2 to slurries resulted in the formation of 14CO2 and the transient appearance of 14C-soluble intermediates, of which acetate was a major component. Acetylene oxidation stimulated sulfate reduction; however, sulfate reduction was not required for the loss of C2H2 to occur. Enrichment cultures were obtained which grew anaerobically at the expense of C2H2. PMID:16345714

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

    NASA Astrophysics Data System (ADS)

    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.

  2. ROLE OF PHYTOTOXICITY AS AN INDICATOR OF ESTUARINE SEDIMENT QUALITY: PLANT-ANIMAL INTERSPECIFIC SENSITIVITY.

    EPA Science Inventory

    Toxicity assessments and numerical quality assessment guidelines for estuarine sediments are rarely based on information for aquatic plants. The effect of this lack of information on contaminated sediment evaluations is largely unknown. For this reason, the toxicities of whole se...

  3. RELEVANCE OF ROOTED VASCULAR PLANTS AS INDICATORS OF ESTUARINE SEDIMENT QUALITY

    EPA Science Inventory

    Toxicity assessments and numerical quality assessment guidelines for estuarine sediments are rarely based on information for aquatic plants. The effect of this lack of information on contaminated sediment evaluations is largely unknown. For this reason, the toxicities of whole se...

  4. RELEVANCE OF ROOTED VASCULAR PLANTS AS INDICATORS OF ESTUARINE SEDIMENT QUALITY

    EPA Science Inventory

    Toxicity assessments and numerical quality assessment guidelines for estuarine sediments are rarely based on information for aquatic plants. The effect of this lack of information on contaminated sediment evaluations is largely unknown. For this reason, the toxicities of whole se...

  5. Impact of silver nanoparticles on benthic prokaryotes in heavy metal-contaminated estuarine sediments in a tropical environment.

    PubMed

    Antizar-Ladislao, B; Bhattacharya, B D; Ray Chaudhuri, S; Sarkar, S K

    2015-10-15

    Little knowledge is available about the potential impact of commercial silver nanoparticles (Ag-NPs) on estuarine microbial communities. The Hugli river estuary, India, is susceptible to heavy metals pollution through boat traffic, and there is the potential for Ag-NP exposure via effluent discharged from ongoing municipal and industrial activities located in close proximity. This study investigated the effects of commercial Ag-NPs on native microbial communities in estuarine sediments collected from five stations, using terminal restriction fragment length polymorphism (T-RFLP) technique. An increase in the number of bacteria in consortium in sediments was observed following exposure to Ag-NPs. In general microbial communities may be resistant in estuarine systems to the antimicrobial effects of commercial Ag-NPs, but key microorganisms, such as Pelobacter propionicus, disappeared following exposure to Ag-NPs. In conclusion, the T-RFLP analysis indicated that Ag-NPs have the potential to shape estuarine sediment bacterial community structure. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Turing Patterns in Estuarine Sediments by Microbiological Activity

    NASA Astrophysics Data System (ADS)

    De Morais Mendonca Teles, Antonio

    2016-07-01

    The use of Turing mechanisms and lattice Lotka-Volterra model (LLV), also by means of the non-extensive statistical mechanics, can mathematically describe well the phenomena of clustering and their associated boundaries with fractal dimensionality, which occurs in various natural situations, among them, biogeochemical processes via microorganisms in estuarine and marine sediments on the planet Earth. The author did an experimental analysis in field work which took into account the spatial and temporal behavior of Turing patterns, in the form of microbial activity within estuarine subsurface sediments. We show we can find the characteristics of clustering and fractallity which are present in the dynamical LLV model and Turing patterns mechanisms, and the non-extensive statistical mechanics could be used to find the q-entropy (Sq), and other non-equilibrium statistical parameters of the studied estuarine (Caraís lagoon) subsurface biogeochemical system. In this paper, the author suggests that such kinds of subsurface ecological systems are of interest to Astrobiology because if we find Turing-type clustered geomorphological patterns, below meter scale, on the near subsurface and inside rocks at the surface of planet Mars, and also find non-equilibrium statistical parameters (temperature, [F], [C], [S], etc.), displaying Turing-type mechanism, in the aquatic environments of the internal seas of planets Jupiter's moon Europa and the internal global ocean of Saturn's moon Enceladus, that could mean that possible hypothetical biogeochemical activities are present in such places. This could be a bio-indicator tool. And with further studies we could find the q-entropy Sq to establish better defined statistical mechanical parameters for such environments and to refine models for their evolution, as we do on planet Earth.

  7. Longshore sediment transport rates on a microtidal estuarine beach

    USGS Publications Warehouse

    Nordstrom, K.F.; Jackson, N.L.; Allen, J.R.; Sherman, D.J.

    2003-01-01

    Longshore sediment transport rates were estimated on a microtidal estuarine beach in Great South Bay, N.Y., during two dyed sand tracer experiments using a temporal sampling method. Mean onshore wind speeds of 5.8 and 9.9 m/s resulted in root-mean-square wave heights of 0.07 and 0.08 m and wave angles of 3.0 and 10.1, causing transport rates of 0.468 and 0.972 m3/h. Rates were 3.1 to 6.5 times greater than predicted by existing equations using standard coefficients. Greater rates are attributed to the concentration of sediment transport in the energetic swash zone under plunging breakers.

  8. Magnetic resonance imaging of bound oils in estuarine sediments

    NASA Astrophysics Data System (ADS)

    Reeves, A. D.; Chudek, J. A.

    2003-04-01

    Whilst it has now been shown that the movement of oil residues in estuarine sediments can be ‘observed’, little has been done to determine the potential of MRI in elucidating the interactions between contaminants and sediment particles. This is of great importance in the assessment of the seriousness and longevity of oil pollution incidents, especially on beaches where oils and sediments interact. The NMR relaxation time T2 can be used as a measure of the viscosity of a liquid. Where the liquid is bound to a substrate T2 decreases inversely with the strength of the binding. Thus, by studying the change in T2 of an oil/sediment mixture with time, it is possible to observe changes in the interaction between the two. By using magnetic resonance imaging (MRI) to create maps of T2 over the area of a slice through the mixture, the distribution of T2 can be directly observed while, simultaneously, the movement and oil concentration gradients within the sample can also be measured. Sediment samples (Tay Estuary, Scotland; 56 26 709N; 03 02 743W) and known quantities of oil were allowed to mix in a 25 mm o.d. container during the course of the experiment. MRI measurements were made on a Bruker AVANCE 300 MHz spectrometer fitted with a Bruker microimaging accessory. The data was obtained using a standard spin-echo technique. Typically acquisitions took one hour and between forty eight and sixty contiguous measurements were made.

  9. Development of formulated reference sediments for freshwater and estuarine sediment testing

    SciTech Connect

    Suedel, B.C.; Rodgers, J.H. Jr. . Dept. of Biology)

    1994-07-01

    Sediments collected at various field locations may have chemical and physical constituents that influence test results and may contain organisms that cannot be readily removed. Thus, reference sediments are needed that can be formulated to match diverse freshwater and estuarine sediments encountered in comprehensive testing programs. This research evaluated formulated reference sediments in terms of (a) their ability to match field-collected sediments both chemically and physically; (b) their suitability as habitant (survival and reproduction) for typical invertebrate toxicity testing species (Hyalella azteca Saussure, Chironomus tentans Fabricius, and Daphnia magna Straus) during chronic exposures; and (c) their suitability as a substrate for Hyalella azteca, Chironomus tentans, Daphnia magna, Ceriodaphnia dubia Richard, and Pimephales promelas Rafinesque in 14-d whole-sediment exposures. Formulated reference sediments were prepared to match naturally occurring sediments with respect to particle-size distribution, organic matter, organic carbon, pH, solids, CEC, but not redox potential. After preparation, a conditioning period of at least 7 d was required for pH stabilization of formulated reference sediments. In culture experiments, formulated reference sediments was suitable for Hyalella azteca, Chironomus tentans, and Daphnia magna survival and reproduction for 56,40, and 28 d, respectively. Hyalella azteca, Chironomus tentans, Daphnia magna, Ceriodaphnia dubia and Pimephales promelas survival was [>=] 88% in 14-d exposures to formulated reference sediment. Formulated reference sediments may reduce some unexplained physical, chemical, or biological toxicity'' of field-collected sediments (e.g., organic matter) that may influence toxicity testing results.

  10. AN EVALUATION OF ELECTRODE INSERTION TECHNIQUES FOR MEASUREMENT OF REDOX POTENTIAL IN ESTUARINE SEDIMENTS

    EPA Science Inventory

    Eh measurements by electrodes are commonly used to characterize redox status of sediments in freshwater, marine and estuarine studies, due to the relative ease and rapidity of data collection. In our studies of fine-grained estuarine seabeds, we observed that Eh values measured i...

  11. Linking DNRA community structure and activity in a shallow lagoonal estuarine system

    PubMed Central

    Song, Bongkeun; Lisa, Jessica A.; Tobias, Craig R.

    2014-01-01

    Dissimilatory nitrate reduction to ammonium (DNRA) and denitrification are two nitrate respiration pathways in the microbial nitrogen cycle. Diversity and abundance of denitrifying bacteria have been extensively examined in various ecosystems. However, studies on DNRA bacterial diversity are limited, and the linkage between the structure and activity of DNRA communities has yet to be discovered. We examined the composition, diversity, abundance, and activities of DNRA communities at five sites along a salinity gradient in the New River Estuary, North Carolina, USA, a shallow temporal/lagoonal estuarine system. Sediment slurry incubation experiments with 15N-nitrate were conducted to measure potential DNRA rates, while the abundance of DNRA communities was calculated using quantitative PCR of nrfA genes encoding cytochrome C nitrite reductase, commonly found in DNRA bacteria. A pyrosequencing method targeting nrfA genes was developed using an Ion Torrent sequencer to examine the diversity and composition of DNRA communities within the estuarine sediment community. We found higher levels of nrfA gene abundance and DNRA activities in sediments with higher percent organic content. Pyrosequencing analysis of nrfA genes revealed spatial variation of DNRA communities along the salinity gradient of the New River Estuary. Percent abundance of dominant populations was found to have significant influence on overall activities of DNRA communities. Abundance of dominant DNRA bacteria and organic carbon availability are important regulators of DNRA activities in the eutrophic New River Estuary. PMID:25232351

  12. Estuarine intertidal sediment temperature variability in Zoster marina and Z. japonica habitats in Yaquina Bay, Oregon

    EPA Science Inventory

    Physical characterization of intertidal estuarine plant habitats over time may reveal distribution-limiting thresholds. Temperature data from loggers embedded in sediment in transects crossing Zostera marina and Z. japonica habitats in lower Yaquina Bay, Oregon display signific...

  13. Estuarine intertidal sediment temperature variability in Zoster marina and Z. japonica habitats in Yaquina Bay, Oregon

    EPA Science Inventory

    Physical characterization of intertidal estuarine plant habitats over time may reveal distribution-limiting thresholds. Temperature data from loggers embedded in sediment in transects crossing Zostera marina and Z. japonica habitats in lower Yaquina Bay, Oregon display signific...

  14. Influence of sediment organic carbon on estuarine benthic species of the US West Coast

    EPA Science Inventory

    Total organic carbon (TOC) is often used as an indicator of nutrient enrichment in estuarine environments. However, the determination of biologically relevant TOC criteria to indicate sediment quality is complicated by the relationship between TOC and grain size. Both variables...

  15. PREDICTING ESTUARINE SEDIMENT METAL CONCENTRATIONS AND INFERRED ECOLOGICAL CONDITIONS: AN INFORMATION THEORETIC APPROACH

    EPA Science Inventory

    Empirically derived values associating sediment metal concentrations with degraded ecological conditions provide important information to assess estuarine condition. However, resources limit the number, magnitude, and frequency of monitoring programs to gather these data. As su...

  16. RESPONSES OF ESTUARINE BENTHIC INVERTEBRATES TO SEDIMENT BURIAL: THE IMPORTANCE OF MOBILITY AND ADAPTATION

    EPA Science Inventory

    Estuarine benthic organisms are frequently subjected to disturbance events caused by hydrodynamic processes that disrupt and move the sediment in which the animals reside, however the mechanisms by which physical disturbance processes affect infaunal and epifaunal populations and...

  17. RESPONSES OF ESTUARINE BENTHIC INVERTEBRATES TO SEDIMENT BURIAL: THE IMPORTANCE OF MOBILITY AND ADAPTATION

    EPA Science Inventory

    Estuarine benthic organisms are frequently subjected to disturbance events caused by hydrodynamic processes that disrupt and move the sediment in which the animals reside, however the mechanisms by which physical disturbance processes affect infaunal and epifaunal populations and...

  18. Influence of sediment organic carbon on estuarine benthic species of the US West Coast

    EPA Science Inventory

    Total organic carbon (TOC) is often used as an indicator of nutrient enrichment in estuarine environments. However, the determination of biologically relevant TOC criteria to indicate sediment quality is complicated by the relationship between TOC and grain size. Both variables...

  19. PREDICTING ESTUARINE SEDIMENT METAL CONCENTRATIONS AND INFERRED ECOLOGICAL CONDITIONS: AN INFORMATION THEORETIC APPROACH

    EPA Science Inventory

    Empirically derived values associating sediment metal concentrations with degraded ecological conditions provide important information to assess estuarine condition. However, resources limit the number, magnitude, and frequency of monitoring programs to gather these data. As su...

  20. Leaching behavior of estuarine sediments and cement-stabilized sediments in upland management environments.

    PubMed

    Gardner, Kevin H; Tsiatsios, Christopher J; Melton, Jeffrey; Seager, Thomas P

    2007-01-01

    Contaminated surficial sediments in major ports and harbors remain a significant economic liability during routine dredging operations. Numerous beneficial uses have been suggested in recent years that promise reduced sediment management costs concomitant with a productive material use. This manuscript describes the leaching of metals and metalloids from surficial sediments and from controlled low strength material (flowable fill) produced using the estuarine sediments as replacement for sand. Sediments from two locations within the New York/New Jersey Harbor area (Gowanus Canal and Newtown Creek) (USA), were subjected to pH-dependent leaching tests and liquid-to-solid ratio dependent leaching tests. Results indicate that, in general, maximum contaminant levels for drinking water, used here as a benchmark for metals concentrations in leachate, were exceeded only at pH values less than 5 or greater than 9. Leaching as a function of increasing liquid-to-solid ratio demonstrated that pH controlled the observed behavior: unamended sediment leached lower concentrations of all elements except for the oxyanion arsenate. The flowable fill material, despite dilution of the sediment and incorporation into a cementitious matrix, leached higher element concentrations except for arsenic due to the high pH of the material. It was also shown that a much more grossly contaminated material (Newtown Creek) had a very similar leaching behavior to the less contaminated Gowanus Canal material. Speciation calculations demonstrated that dissolved organic carbon plays a significant role in the leaching observed from these estuarine sediments and the flowable fill made with the high organic matter content sediments.

  1. Harmonised framework for ecological risk assessment of sediments from ports and estuarine zones of North and South Atlantic.

    PubMed

    Choueri, R B; Cesar, A; Abessa, D M S; Torres, R J; Riba, I; Pereira, C D S; Nascimento, M R L; Morais, R D; Mozeto, A A; DelValls, T A

    2010-04-01

    This paper presents a harmonised framework of sediment quality assessment and dredging material characterisation for estuaries and port zones of North and South Atlantic. This framework, based on the weight-of-evidence approach, provides a structure and a process for conducting sediment/dredging material assessment that leads to a decision. The main structure consists of "step 1" (examination of available data); "step 2" (chemical characterisation and toxicity assessment); "decision 1" (any chemical level higher than reference values? are sediments toxic?); "step 3" (assessment of benthic community structure); "step 4" (integration of the results); "decision 2" (are sediments toxic or benthic community impaired?); "step 5" (construction of the decision matrix) and "decision 3" (is there environmental risk?). The sequence of assessments may be interrupted when the information obtained is judged to be sufficient for a correct characterisation of the risk posed by the sediments/dredging material. This framework brought novel features compared to other sediment/dredging material risk assessment frameworks: data integration through multivariate analysis allows the identification of which samples are toxic and/or related to impaired benthic communities; it also discriminates the chemicals responsible for negative biological effects; and the framework dispenses the use of a reference area. We demonstrated the successful application of this framework in different port and estuarine zones of the North (Gulf of Cádiz) and South Atlantic (Santos and Paranaguá Estuarine Systems).

  2. Evaluation of the contamination of platinum in estuarine and coastal sediments (Tagus Estuary and Prodelta, Portugal).

    PubMed

    Cobelo-García, Antonio; Neira, Patricia; Mil-Homens, Mario; Caetano, Miguel

    2011-03-01

    Platinum contamination in estuarine and coastal sediments has been evaluated in three cores collected from the Tagus Estuary and Prodelta shelf sediments. Elevated concentrations, up to 25-fold enrichment compared to background values, were found in the upper layers of the estuarine sediments. The degree of Pt enrichment in the estuarine sediments varied depending on the proximity to vehicular traffic sources, with a maximum concentration of 9.5 ng g(-1). A considerable decrease of Pt concentrations with depth indicated the absence of significant contamination before the introduction of catalytic converters in automobiles. Platinum distribution in the Tagus Prodelta shelf sediment core showed no surface enrichment; instead a sub-surface maximum at the base of the mixed layer suggested the possibility of post-depositional mobility, thereby blurring the traffic-borne contamination signature in coastal sediments. Copyright © 2011. Published by Elsevier Ltd.

  3. Toward Understanding the Dynamics of Microbial Communities in an Estuarine System

    PubMed Central

    Wang, Yong; Lee, On On; Yang, Jiangke; Chan, Colin; Song, Xingyu; Qian, Pei-Yuan

    2014-01-01

    Community assembly theories such as species sorting theory provide a framework for understanding the structures and dynamics of local communities. The effect of theoretical mechanisms can vary with the scales of observation and effects of specific environmental factors. Based on 16S rRNA gene tag pyrosequencing, different structures and temporal succession patterns were discovered between the surface sediments and bottom water microbial communities in the Pearl River Estuary (PRE). The microbial communities in the surface sediment samples were more diverse than those in the bottom water samples, and several genera were specific for the water or sediment communities. Moreover, water temperature was identified as the main variable driving community dynamics and the microbial communities in the sediment showed a greater temporal change. We speculate that nutrient-based species sorting and bacterial plasticity to the temperature contribute to the variations observed between sediment and water communities in the PRE. This study provides a more comprehensive understanding of the microbial community structures in a highly dynamic estuarine system and sheds light on the applicability of ecological theoretical mechanisms. PMID:24732211

  4. Distribution of Sulfate-Reducing Communities from Estuarine to Marine Bay Waters.

    PubMed

    Colin, Yannick; Goñi-Urriza, Marisol; Gassie, Claire; Carlier, Elisabeth; Monperrus, Mathilde; Guyoneaud, Rémy

    2017-01-01

    Estuaries are highly dynamic ecosystems in which freshwater and seawater mix together. Depending on tide and river inflows, particles originating from rivers or from the remobilization of sediments accumulate in the water column. Due to the salinity gradient and the high heterotrophic activity in the estuarine plume, hypoxic and anoxic microniches may form in oxygenated waters, sustaining favorable conditions for resuspended anaerobic microorganisms. In this context, we tested the hypothesis that anaerobic sulfate-reducing prokaryotes may occur in the water column of the Adour River. Using 16S ribosomal RNA (rRNA) and dsrAB-based terminal restriction fragment length polymorphism (T-RFLP) techniques, we characterized total prokaryotic and sulfate-reducing communities along a gradient from estuarine to marine bay waters. Sulfate-reducing prokaryotes were further characterized by the description of dsrB genes and the cultivation of sulfidogenic anaerobic microorganisms. As a result, physical-chemical parameters had a significant effect on water bacterial diversity and community structure along the studied gradient. The concentration of cultured sulfidogenic microorganisms ranged from 1 to 60 × 10(3) cells l(-1) in the water column. Sulfate-reducing prokaryotes occurring in estuarine waters were closely related to microorganisms previously detected in freshwater sediments, suggesting an estuarine origin, mainly by the remobilization of the sediments. In the marine bay station, sediment-derived sulfate-reducing prokaryotes were not cultured anymore, probably due to freshwater dilution, increasing salinity and extended oxic stress. Nevertheless, isolates related to the type strain Desulfovibrio oceani were cultured from the diluted plume and deep marine waters, indicating the occurrence of autochthonous sulfate-reducing bacteria offshore.

  5. Reductive dechlorination of chlorophenols in estuarine sediments of Lake Shinji and Lake Nakaumi.

    PubMed

    Itoh, Kazuhito; Mihara, Yoichi; Tanimoto, Naoya; Shimada, Tetsuo; Suyama, Kousuke

    2010-07-01

    Dechlorination of all mono- and dichlorophenol isomers in anaerobic sediment samples of estuarine Lake Shinji and Lake Nakaumi was examined to characterize the chlorophenol-dechlorinating microbial communities in the environments with different salinity levels. Dechlorination was observed only in 2-chlorophenol (2-CP), 3-chlorophenol (3-CP) and 2,6-dichlorophenol (2,6-DCP), and in 2-CP and 2,6-DCP in the Lake Shinji and Nakaumi sediment, respectively. In the sediment of Lake Shinji, the highest activity was observed without adding sodium chloride and sulfate, whereas in the Lake Nakaumi sediment, the highest activity was at 0.7 % of sodium chloride and 6.0 mM of sodium sulfate. The chlorophenols were degraded to benzoate via phenol in both sediments under methanogenic conditions. Benzoate then disappeared from the cultures. All microbial consortia enriched with each monochlorophenol dechlorinated 2-CP, but showed different substrate specificities for dichlorophenols as follows: 2-CP-enriched consortium dechlorinated 2,3-dichlorophenol and 2,6-DCP, 3-CP-enriched consortium dechlorinated all dichlorophenol isomers, and 4-chlorophenol-enriched consortium dechlorinated 2,4-dichlorophenol and 2,6-DCP. Maintenance of the population by halorespiration was suggested in the dechlorination of 2-CP.

  6. Impact of boat-generated waves on intertidal estuarine sediments

    NASA Astrophysics Data System (ADS)

    Blanpain, O.; Deloffre, J.; Lafite, R.; Gomit, G.; Calluaud, D.; David, L.

    2010-12-01

    Hydrodynamics in the macrotidal Seine estuary (France) are controlled by the semi-diurnal tidal regime modulated seasonally by the fluvial discharge. Wind effect on sediment transport (through wind waves and swell) is observed at the mouth of the estuary. Over the last century, authorities have put emphasis on facilitating economic exchanges by means of embankment building and increased dredging activity. These developments led to allow and secure sea vessel traffic in the Seine estuary (from its mouth to the port of Rouen, 125 km upstream) but they also resulted in a change of estuarine hydrodynamics and sediment transport features. A riversides restoration policy has been recently started by port authorities. In this context, the objective of the field-based study presented is to connect vessel characteristics (i.e. speed, draft...), boat-generated waves and their sedimentary impacts. Such information will be used by stakeholders to manage riverside. The natural intertidal site of interest is located in the fluvial freshwater part of the Seine estuary characterized by a 4.5 m maximum tidal range. The foreshore slope is gently decreasing and surface sediments are composed of fine to coarse sand with occasional mud drapes. In order to decipher boat-generated events, the sampling strategy is based on continuous ADV measurements coupled with a turbidimeter and an altimeter to study sediment dynamics. These instruments are settled in the lower part of the foreshore (i) to obtain a significant dataset (i.e. oceanic instruments are not measuring in air) on a zone statically affected by boat waves and (ii) because most of boat traffic occurs during early flood or late ebb period. Spatial variations are assessed along a cross-section through grain-size analysis of surface sediments and topography measurements using pole technique. Results enhance hydrodynamic and sedimentary impacts of boat-generated waves compared respectively to tidal and wind effects. Long

  7. Fate of Triclosan and Evidence for Reductive Dechlorination of Triclocarban in Estuarine Sediment

    USDA-ARS?s Scientific Manuscript database

    The biocides triclosan (TCS) and triclocarban (TCC) are wastewater contaminants whose occurrence and fate in estuarine sediments remain unexplored. We examined contaminant profiles in 137Cs/7Be-dated sediment cores taken near wastewater treatment plants in the Chesapeake Bay watershed (CB), Maryland...

  8. MICROBIAL DIVERSITY IN SURFACE SEDIMENTS: A COMPARISON OF TWO ESTUARINE CONTINUUMS

    EPA Science Inventory

    The microbial diversity in estuarine sediments of the Altamaha and Savannah Rivers in Georgia were compared temporally and spatially using phospholipid fatty acid (PLFA) analysis. Surface sediment samples collected along a salinity gradient were also analyzed for ATP, TOC, and C ...

  9. SALINITY TOLERANCE OF DAPHNIA MAGNA AND POTENTIAL USE FOR ESTUARINE SEDIMENT TOXICITY TESTS

    EPA Science Inventory

    Daphnia magna Straus, a common organism used for freshwater sediment toxicity tests, was evaluated to determine its tolerance to salinity and suitability for tests with estuarine water and sediments. Daphnids were exposed for 2 to 21 days to salinity in a variety of water-only te...

  10. MICROBIAL DIVERSITY IN SURFACE SEDIMENTS: A COMPARISON OF TWO ESTUARINE CONTINUUMS

    EPA Science Inventory

    The microbial diversity in estuarine sediments of the Altamaha and Savannah Rivers in Georgia were compared temporally and spatially using phospholipid fatty acid (PLFA) analysis. Surface sediment samples collected along a salinity gradient were also analyzed for ATP, TOC, and C ...

  11. Macro and micro scale interactions between cohesive sediment tracers and natural estuarine mud.

    NASA Astrophysics Data System (ADS)

    Spencer, K. L.; Manning, A. J.; Droppo, I. G.; Leppard, G. G.; Benson, T.

    2009-04-01

    Improving the understanding of dispersion patterns of the fine sediment fraction (< 63 micron) and associated contaminants is fundamental to the sustainable management of estuarine and marine environments. In order to develop sediment transport models and predict sediment dispersion, accurate and reliable field techniques for the measurement of sediment transport are required. Although this is relatively simple for the sand sized fraction, measuring transport pathways for the < 63 micron sediment fraction has been more problematic. There has been considerable effort within the scientific community to develop a tracer for the fine/cohesive sediment fraction. This has included the use of synthetic tracer particles and the labelling of natural clays (e.g. Mahler et al. 1998, Yin et al. 1999, Krezoski 1985; Spencer et al. 2007). Synthetic tracers have included polymer-based fluorescent tracers, with the same size, density and surface charge characteristics as the flocculated clay and silt fraction. A fundamental assumption of tracer technology is that the tracer has the same physical properties as the natural sediment it is intended to mimic. For sand-sized material matching particle size, shape and density has been easy to achieve. However, the < 63 micron sediment fraction is cohesive and in order to satisfy this assumption cohesive sediment tracers must be incorporated into and transported via floc aggregates (Black et al. 2006). This work focuses on the use of a labelled natural clay; a Ho-montmorillonite (see Spencer et al. 2007). The aim of the research was to determine whether this tracer interacted with and was transported via floc aggregates in saline environments and would therefore be a suitable cohesive sediment tracer in estuaries. Our objectives were to examine the physical characteristics, internal structure and settling dynamics of flocculated tracer and to determine the extent to which the tracer interacted with natural estuarine muds under laboratory

  12. Significance of antifouling paint flakes to the distribution of dichlorodiphenyltrichloroethanes (DDTs) in estuarine sediment.

    PubMed

    Wu, Chen-Chou; Bao, Lian-Jun; Tao, Shu; Zeng, Eddy Y

    2016-03-01

    Recently published literature indicated that dichlorodiphenyltrichloroethane (DDT)-containing antifouling paint flakes were heterogeneously distributed within estuarine sediments. However, the significance of antifouling paint flakes in the fate and transport of DDT compounds and other organic pollutants in estuarine sediment is yet to be adequately addressed. To fill this knowledge gap, estuarine sediment and paint flakes from cabin and boat surfaces were collected from a fishery base in Guangdong Province of South China and analyzed for DDT compounds. Coarse fractioned samples collected from the vicinity of boat maintenance facilities contained appreciable amounts of colorful particles, which were identified as paint flakes by Fourier transform infrared spectroscopy. The highest concentrations of DDXs (sum of DDTs and its metabolites) occurred in the heavy-density (>1.7 g cm(-3)) fraction of coarse-size (200-2000 μm) sediments from near the boat maintenance facilities, suggesting the importance of paint flakes in the distribution pattern of "hot spots" in estuarine sediment. Moreover, the desorption rates of DDT compounds from paint flakes and the heavy-density fraction of coarse-size sediment were both extremely slow. Apparently, unevenly distributed paint flakes in sediment can artificially inflate the sorption capacity of heavy-density sediment for DDT compounds, and therefore can substantially change the environmental fate and behavior of hydrophobic organic chemicals in estuarine sediment. Finally, commonly used source diagnostic indices of DDT compounds were mostly grain-size and density dependent in sediment, as a result of the occurrence of paint flakes, which may strongly compromise the outcome of any source diagnostics efforts.

  13. Dynamics of the Methanogenic Archaea in Tropical Estuarine Sediments

    PubMed Central

    Torres-Alvarado, María del Rocío; Fernández, Francisco José; Ramírez Vives, Florina; Varona-Cordero, Francisco

    2013-01-01

    Methanogenesis may represent a key process in the terminal phases of anaerobic organic matter mineralization in sediments of coastal lagoons. The aim of the present work was to study the temporal and spatial dynamics of methanogenic archaea in sediments of tropical coastal lagoons and their relationship with environmental changes in order to determine how these influence methanogenic community. Sediment samples were collected during the dry (February, May, and early June) and rainy seasons (July, October, and November). Microbiological analysis included the quantification of viable methanogenic archaea (MA) with three substrates and the evaluation of kinetic activity from acetate in the presence and absence of sulfate. The environmental variables assessed were temperature, pH, Eh, salinity, sulfate, solids content, organic carbon, and carbohydrates. MA abundance was significantly higher in the rainy season (106–107 cells/g) compared with the dry season (104–106 cells/g), with methanol as an important substrate. At spatial level, MA were detected in the two layers analyzed, and no important variations were observed either in MA abundance or activity. Salinity, sulfate, solids, organic carbon, and Eh were the environmental variables related to methanogenic community. A conceptual model is proposed to explain the dynamics of the MA. PMID:23401664

  14. Dynamics of the methanogenic archaea in tropical estuarine sediments.

    PubMed

    Torres-Alvarado, María del Rocío; Fernández, Francisco José; Ramírez Vives, Florina; Varona-Cordero, Francisco

    2013-01-01

    Methanogenesis may represent a key process in the terminal phases of anaerobic organic matter mineralization in sediments of coastal lagoons. The aim of the present work was to study the temporal and spatial dynamics of methanogenic archaea in sediments of tropical coastal lagoons and their relationship with environmental changes in order to determine how these influence methanogenic community. Sediment samples were collected during the dry (February, May, and early June) and rainy seasons (July, October, and November). Microbiological analysis included the quantification of viable methanogenic archaea (MA) with three substrates and the evaluation of kinetic activity from acetate in the presence and absence of sulfate. The environmental variables assessed were temperature, pH, Eh, salinity, sulfate, solids content, organic carbon, and carbohydrates. MA abundance was significantly higher in the rainy season (10(6)-10(7) cells/g) compared with the dry season (10(4)-10(6) cells/g), with methanol as an important substrate. At spatial level, MA were detected in the two layers analyzed, and no important variations were observed either in MA abundance or activity. Salinity, sulfate, solids, organic carbon, and Eh were the environmental variables related to methanogenic community. A conceptual model is proposed to explain the dynamics of the MA.

  15. Estuarine sediment acute toxicity testing with the European amphipod Corophium multisetosum Stock, 1952.

    PubMed

    Ré, Ana; Freitas, Rosa; Sampaio, Leandro; Rodrigues, Ana Maria; Quintino, Victor

    2009-09-01

    This study assessed the use of the European amphipod Corophium multisetosum Stock [Stock, J.H., 1952. Some notes on the taxonomy, the distribution and the ecology of four species of the genus Corophium (Crustacea, Malacostraca). Beaufortia 21, 1-10] in estuarine sediment acute toxicity testing. The sensitivity of adults to the reference toxicant CdCl(2) was determined in water-only 96 h exposures in salinity 2. LC(50) values ranged from 0.33mgCd(2+)L(-1) at 22 degrees C to 0.57mgCd(2+)L(-1) at 15 degrees C. Adult survival was studied in control sediment with water salinity from 0 to 36 and with fine particles content (<63 microm) from 2% to 97% of total sediment, dry weight. Experiments were conducted at 15, 18 and 22 degrees C and the results indicate that the species can be used under the full salinity range although higher mortality was observed at the lower salinity in the higher water temperature, and at the higher salinity in the lower water temperature. The species also tolerated the studied range of sediment fines content and showed the highest sensitivity at intermediate values of fines, especially at the higher temperature, thus advising that tests which have to accommodate sediments with a wide range in fines content should preferably be conducted at 15 degrees C rather than at 22 degrees C. The response in natural sediments was studied in samples collected yearly from 1997 to 2006, at a site located off the Tagus Estuary, western Portugal. A major flood event in winter 2000-2001 induced detectable alterations in sediment baseline descriptors (grain-size, redox potential and total volatile solids), organic contaminants (PAHs, PCBs, DDT metabolites and gamma-HCH) and the macrofauna benthic community. Mortality of the amphipod diminished significantly from the before to the after flood period, in close agreement with diminishing sediment contamination and increasing benthic fauna diversity, in the same time period. C. multisetosum is suitable to conduct

  16. Importance of allochthonous material in benthic macrofaunal community functioning in estuarine salt marshes

    NASA Astrophysics Data System (ADS)

    Kon, Koetsu; Hoshino, Yukihiro; Kanou, Kouki; Okazaki, Daisuke; Nakayama, Satoko; Kohno, Hiroshi

    2012-01-01

    Allochthonous input provides important food and spatial resources for estuarine benthic fauna. While it is known that autochthonous materials are important for fauna occupying small marshes, here, we present the significance of allochthonous materials for benthic fauna inhabiting a large salt marsh. To assess the effects of allochthonous input on benthic macrofaunal communities in estuarine salt marshes, we determined the source of substrate sediments and food resource utilisation patterns of benthic invertebrates in 2 temperate estuaries (the Tama River and the Obitsu River estuarine outlets into Tokyo Bay) by using stable carbon and nitrogen isotope analyses. In the Tama River estuary, which has small patches of marsh vegetation upstream of the river mouth, there was an input of sedimentary organic matter from autochthonous sources (i.e. common reed and microphytobenthos). In the Obitsu River estuary salt marsh, which is situated immediately upstream of the river mouth and is well connected to the sea, sediment consists of allochthonous sources (i.e. imported phytoplankton), along with microphytobenthos. Isotope analysis indicated that most benthic invertebrates in the Tama River estuary depend on benthic microalgae (autochthonous) as a food resource, whereas the macrofauna in the Obitsu River estuary are supported by drift macroalgae (allochthonous), in addition to microphytobenthos or phytoplankton. Our results indicated that allochthonous material provides a food resource and potential habitat for benthic macrofauna in extensive salt marshes that have a strong connection to the sea but is not substantial in smaller marshes with limited connectivity to coastal water.

  17. Assessment of human-induced change and biological risk posed by contaminants in estuarine/harbour sediments: Sydney Harbour/estuary (Australia).

    PubMed

    Birch, G F

    2017-03-15

    A rapid, simple yet scientifically sound scheme providing two important types of information used in assessment of estuarine sediments is presented. The mean enrichment quotient (MEQ) (fine contemporary sediment metal concentration/fine fraction background metal concentration) for Cu, Pb and Zn provides the magnitude of human-induced change, (deviation from the pristine condition), while sediment quality guidelines (SQGs) assess the risk posed by sedimentary contaminants to the benthic community. Maximum metal enrichment for sediment in Sydney estuary (Australia) is >100 times for Cu, Pb and Zn and the MEQ is >10 times for most of the estuary. Adverse effect on benthic populations due to Cu, Pb and Zn are expected in 2%, 50% and 36% of the waterway, respectively. SQGs for contaminant mixtures predict ~2% of the estuary has the highest risk of adverse effects, while 25% has intermediate risk. The scheme is well suited to initial assessments of estuarine sediments worldwide. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Accumulation and trace-metal variability of estuarine sediments, St. Bernard delta geomorphic region, Louisiana

    SciTech Connect

    Landrum, K.E.

    1995-10-01

    Prior to government regulation, little monitoring of metal discharges into the canals, bayous, and rivers that drain estuarine systems occured. Discharges of trace-metals by industries and municipalities into surface water bodies are presently regulated through the use of Federal and State mandated permit programs. Resource management of economically important estuarine systems has fostered increasing concern over the accumulation of trace-metal pollutants in water, sediments, and biota from these dynamic areas. The acid-leachable concentrations of fourteen trace-metals were determined for 125 bottom sediment samples and 50 core interval samples by plasma emission analysis. Bottom sediments of the St. Bernard estuarom complex consist predominantly of silty clays and clayey silts derived from the erosion of the St. Bernard lobe of the Mississippi River delta and sediments associated with historic crevasses along the Mississippi River. Within the 2 cm core intervals, trace-metal concentrations of Ba, Cr, Cd, Pb, and Zn increased by 10% to 18% in sediments accumulated within the last 75 years. Trace-metal concentrations from sediments for the study area tend to have greater mean concentrations than Florida estuarine sediments, basinwide and Gulf Coast trace-metal comparisons, sediment geochronology. Rates varied from 0.12 to 0.21 cm/yr. Within the 2 cm core intervals, trace-metal concentrations of Ba, Cr, Cd, Pb, and Zn increased by 10% to 18% in sediments accumulated within the last 75 years. Natural trace-metal variability was examined through the use of an aluminum normalization model based on Florida and Louisiana estuarine sediments, basinwide and Gulf Coast trace-metal comparisons, sediment geochronology, and grain-size corrected data. Elevated concentrations of As, Ba, Cd, Pb, V and Zn were noted from sediments associated with oil and gas drilling and production, sandblasting and shipbuilding, dredging, and stormwater, municipal, and industrial discharges.

  19. Persistence and Degradation Pathways of Tributyltin in Freshwater and Estuarine Sediments

    NASA Astrophysics Data System (ADS)

    Dowson, P. H.; Bubb, J. M.; Lester, J. N.

    1996-05-01

    The degradation of tributyltin (TBT) in contaminated freshwater and estuarine sediments was investigated for a 330-day period under controlled laboratory conditions. Rates of TBT degradation at different depths within various sediments were established, where possible, using regression modelling, and revealed TBT half-lives ranging from 360 to 775 days in surficial sediments. There appeared to be very little difference between degradation rates in freshwater and estuarine sediments, although a notable increase in TBT half-life was evident in spiked sediments containing elevated TBT concen-trations. Degradation trends suggest that TBT either debutylates to dibutyltin (DBT) and monobutyltin (MBT) in aerobic sediments or degrades to DBT which subsequently desorbs to the overlying water column. In anaerobic sediment, the half-life of TBT was not discernible and appears to be in the order of tens of years. Biotic processes were the most important mechanisms for the decomposition of TBT in freshwater and estuarine sediments. The results are reviewed in the context of concentrations of TBT determined in marina and boatyard sediments in U.K. east coast estuaries.

  20. Hydrodynamic conditioning of diversity and functional traits in subtidal estuarine macrozoobenthic communities

    NASA Astrophysics Data System (ADS)

    van der Wal, Daphne; Lambert, Gwladys I.; Ysebaert, Tom; Plancke, Yves M. G.; Herman, Peter M. J.

    2017-10-01

    Variations in abundance and diversity of estuarine benthic macrofauna are typically described along the salinity gradient. The influence of gradients in water depth, hydrodynamic energy and sediment properties are less well known. We studied how these variables influence the distribution of subtidal macrofauna in the polyhaline zone of a temperate estuary (Westerschelde, SW Netherlands). Macrofauna density, biomass and species richness, combined in a so-called ecological richness, decreased with current velocities and median grain-size and increased with organic carbon of the sediment, in total explaining 39% of the variation. The macrofauna community composition was less well explained by the three environmental variables (approx. 12-15% in total, with current velocity explaining approx. 8%). Salinity, water depth and distance to the intertidal zone had a very limited effect on both ecological richness and the macrofauna community. The proportion of (surface) deposit feeders (including opportunistic species), decreased relative to that of omnivores and carnivores with increasing current velocity and sediment grain-size. In parallel, the proportion of burrowing sessile benthic species decreased relative to that of mobile benthic species that are able to swim. Correspondingly, spatial variations in hydrodynamics yielded distinct hotspots and coldspots in ecological richness. The findings highlight the importance of local hydrodynamic conditions for estuarine restoration and conservation. The study provides a tool based on a hydrodynamic model to assess and predict ecological richness in estuaries.

  1. Evaluation of rhamnolipid addition on the natural attenuation of estuarine sediments contaminated with diesel oil.

    PubMed

    Nakazawa, Mitsue M; Gavazza, Sávia; Kato, Mario T; Florencio, Lourdinha

    2016-07-07

    The aim of the present study was to assess the bioremediation of estuarine sediments contaminated with diesel oil. The following two experiments were performed: natural attenuation (NA) and stimulated natural attenuation (SNA), using rhamnolipid as biosurfactant. Sediment samples were accommodated into glass columns and then contaminated with diesel oil on the top. The column profiles were separated into surface, middle, and bottom for the analyses. The 16 polycyclic aromatic hydrocarbons (PAHs) prioritized by US Environmental Protection Agency (EPA) were monitored for 349 days. Those with three and four rings showed increasing concentrations through the operation period in the middle and bottom samples, particularly between days 111 and 338, and in the SNA experiment. Those with five and six rings were also detected in the deeper portions of the columns, suggesting the percolation of PAHs with a high molecular weight. Total organic carbon was reduced by 91 and 89 % in the NA and SNA samples, respectively, although no statistically significant differences (p > 0.05) were found between the two treatments. The analyses by denaturing gradient gel electrophoresis indicated a slight shift in the microbial community structure over the experiments. Microorganisms belonging to the γ-Proteobacteria phylum were the main bacteria involved. The archaeal community exhibited dominance of hydrogenotrophic methanogens, indicating the obligate anaerobic biodegradation of intermediate compounds from hydrocarbon degradation.

  2. Comparison of estuarine sediment record with modelled rates of sediment supply from a western European catchment since 1500

    NASA Astrophysics Data System (ADS)

    Poirier, Clément; Poitevin, Cyril; Chaumillon, Éric

    2016-09-01

    Marine and estuarine sediment records reporting impacts of historical land use changes exist worldwide, but they are rarely supported by direct quantified evidence of changes in denudation rates on the related catchments. Here we implement a spatially-resolved RUSLE soil erosion model on the 10 000 km2 Charente catchment (France), supplied with realistic scenarios of land-cover and climate changes since 1500, and compare the results to a 14C-dated estuarine sediment record. Despite approximations, the model correctly predicts present-day Charente river sediment load. Back-cast modelling suggests that the Charente catchment is an interesting case where the sediment supply did not change despite increase in soil erosion resulting from 18th-century deforestation because it was mitigated by drier climate during the same period. Silt-sand alternations evidenced in the sediment record were correlated with sub-decadal rainfall variability.

  3. The Abundance and Activity of Nitrate-Reducing Microbial Populations in Estuarine Sediments

    NASA Astrophysics Data System (ADS)

    Cardarelli, E.; Francis, C. A.

    2014-12-01

    Estuaries are productive ecosystems that ameliorate nutrient and metal contaminants from surficial water supplies. At the intersection of terrestrial and aquatic environments, estuarine sediments host major microbially-mediated geochemical transformations. These include denitrification (the conversion of nitrate to nitrous oxide and/or dinitrogen) and dissimilatory nitrate reduction to ammonium (DNRA). Denitrification has historically been seen as the predominant nitrate attenuation process and functions as an effective sink for nitrate. DNRA has previously been believed to be a minor nitrate reduction process and transforms nitrate within the ecosystem to ammonium, a more biologically available N species. Recent studies have compared the two processes in coastal environments and determined fluctuating environmental conditions may suppress denitrification, supporting an increased role for DNRA in the N cycle. Nitrate availability and salinity are factors thought to influence the membership of the microbial communities present, and the nitrate reduction process that predominates. The aim of this study is to investigate how nitrate concentration and salinity alter the transcript abundances of N cycling functional gene markers for denitrification (nirK, nirS) and DNRA (nrfA) in estuarine sediments at the mouth of the hypernutrified Old Salinas River, CA. Short-term whole core incubations amended with artificial freshwater/artificial seawater (2 psu, 35 psu) and with varying NO3- concentrations (200mM, 2000mM) were conducted to assess the activity as well as the abundance of the nitrate-reducing microbial populations present. Gene expression of nirK, nirS, and nrfA at the conclusion of the incubations was quantified using reverse transcription quantitative polymerase chain reaction (RT-qPCR). High abundances of nirK, nirS, and nrfA under particular conditions coupled with the resulting geochemical data ultimately provides insight onto how the aforementioned factors

  4. Natural trace metal concentrations in estuarine and coastal marine sediments of the southeastern United States

    SciTech Connect

    Windom, H.L.; Schropp, S.J.; Calder, F.D.; Ryan, J.D.; Smith, R.G. Jr.; Burney, L.C.; Lewis, F.G.; Rawlinson, C.H.

    1989-03-01

    Over 450 sediment samples from estuarine and coastal marine areas of the southeastern US remote from contaminant sources were analyzed for trace metals. Although these sediments are compositionally diverse, As, Co, Cr, Cu, Fe, Pb, Mn, Ni, and Zn concentrations covary significantly with aluminum, suggesting that natural aluminosilicate minerals are the dominant natural metal bearing phases. Cd and Hg do not covary with aluminum apparently due to the importance of the contribution of natural organic phases to their concentration in sediments. It is suggested that the covariance of metals with aluminum provides a useful basis for identification and comparison of anthropogenic inputs to southeastern US coastal/estuarine sediments. By use of this approach sediments from the Savannah River, Biscayne Bay, and Pensacola Bay are compared.

  5. Interactions of Cd and Cu in anaerobic estuarine sediments. 1: Partitioning in geochemical fractions of sediments

    SciTech Connect

    Rule, J.H.; Alden, R.W. III

    1996-04-01

    Partitioning of Cd and Cu between geochemical fractions of an anaerobic estuarine sediment was determined after equilibrating fine-sandy sediment with different combinations of added Cd (0, 2.5, 5 mg/kg) and Cu(0, 12.5, 25 mg/kg). Sediments were placed in aquaria with 20 ppt seawater where bioassay test organisms were exposed for 14 d. At the start and conclusion of the experimental period, sediments were sequentially extracted to determine the elemental content of the exchangeable (EP), easily reducible (ERP), organic- sulfide (OSP), moderately reducible (MRP), and acid extractable (AEP) phases. Partitioning of the metals in both the native and treated sediments was, for Cd: OSP {much_gt} ERP > AEP > EP (MRP was below detection) and for Cu: OSP {much_gt} AEP > ERP > MRP > EP. Cadmium extracted in all phases and Cu in the EP, RP, and OSP were proportional to the respective treatments. The EP-Cd, ERP-Cd, and OSP-Cd were affected by the Cu treatment and significant interactions occurred between Cd and Cu for the EP-Cd, ERP-Cd, OSP-Cd, EP-Cu, and ERP-Cu. Increasing levels of applied Cd and Cu resulted in greater amounts of EP-Cd and ERP-Cd, fractions that are the most bioavailable and the most readily available for desorption into the water column. A significant conclusion is that the input of nontoxic metals may affect the geochemical phase distribution, potential bioavailability, and toxicity of native sediment metals.

  6. BENTHIC COMMUNITY RESPONSE TO SEDIMENT AMENDMENTS

    EPA Science Inventory

    The amendments apatite, organoclay, acetate, chitin, and geotextile reactive mats containing apatite and apatite + organoclay are currently under examination for remediation of contaminated sediments. The objective of this research is to evaluate toxicity to several estuarine an...

  7. BENTHIC COMMUNITY RESPONSE TO SEDIMENT AMENDMENTS

    EPA Science Inventory

    The amendments apatite, organoclay, acetate, chitin, and geotextile reactive mats containing apatite and apatite + organoclay are currently under examination for remediation of contaminated sediments. The objective of this research is to evaluate toxicity to several estuarine an...

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

    SciTech Connect

    Sims, I.; Fleming, R.

    1995-12-31

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

  9. Development of a chronic sublethal sediment bioassay using the estuarine amphipod Leptocheirus plumulosus (Shoemaker)

    SciTech Connect

    Emery, V.L. Jr.; Moore, D.W.; Gibson, A.B.; Gray, B.R.; Duke, B.M.; Wright, R.B.; Farrar, J.D.

    1997-09-01

    Based on the need for a test to evaluate chronic sublethal toxicity in estuarine sediments, a 28-d sediment bioassay with the estuarine amphipod, Leptocheirus plumulosus (Shoemaker) was developed. The test was initiated with animals less than 2 weeks old. Test endpoints included survival, growth, and reproduction. Factors with the potential to influence test animal performance such as artificial sea salts, salinity, food ration, size at test initiation, intraspecific density, sediment grain size, and diet were evaluated. For example, intraspecific densities between 10 and 60 animals/beaker did not affect survival, growth, or reproduction. Similarly, L. plumulosus were tolerant of a wide range of sediment grain sizes with only extremely fine grained or coarse grained material significantly affecting survival, growth, and reproduction. Test performance criteria included control survival (> 80%) and reproduction and response to a reference toxicant test with cadmium chloride in a control chart format.

  10. Seasonal variations in suspended-sediment dynamics in the tidal reach of an estuarine tributary

    USGS Publications Warehouse

    Downing-Kunz, Maureen A.; Schoellhamer, David H.

    2013-01-01

    Quantifying sediment supply from estuarine tributaries is an important component of developing a sediment budget, and common techniques for estimating supply are based on gages located above tidal influence. However, tidal interactions near tributary mouths can affect the magnitude and direction of sediment supply to the open waters of the estuary. We investigated suspended-sediment dynamics in the tidal reach of Corte Madera Creek, an estuarine tributary of San Francisco Bay, using moored acoustic and optical instruments. Flux of both water and suspended-sediment were calculated from observed water velocity and turbidity for two periods in each of wet and dry seasons during 2010. During wet periods, net suspended-sediment flux was seaward; tidally filtered flux was dominated by the advective component. In contrast, during dry periods, net flux was landward; tidally filtered flux was dominated by the dispersive component. The mechanisms generating this landward flux varied; during summer we attributed wind–wave resuspension in the estuary and subsequent transport on flood tides, whereas during autumn we attributed increased spring tide flood velocity magnitude leading to local resuspension. A quadrant analysis similar to that employed in turbulence studies was developed to summarize flux time series by quantifying the relative importance of sediment transport events. These events are categorized by the direction of velocity (flood vs. ebb) and the magnitude of concentration relative to tidally averaged conditions (relatively turbid vs. relatively clear). During wet periods, suspended-sediment flux was greatest in magnitude during relatively turbid ebbs, whereas during dry periods it was greatest in magnitude during relatively turbid floods. A conceptual model was developed to generalize seasonal differences in suspended-sediment dynamics; model application to this study demonstrated the importance of few, relatively large events on net suspended-sediment flux

  11. Aggregation, sedimentation, dissolution and bioavailability of quantum dots in estuarine systems.

    EPA Science Inventory

    To understand their fate and transport in estuarine systems, the aggregation, sedimentation, and dissolution of CdSe quantum dots (QDs) in seawater were investigated. Hydrodynamic size increased from 40 to 60 nm to >1 mm within 1 h in seawater, and the aggregates were highly p...

  12. Aggregation, sedimentation, dissolution and bioavailability of quantum dots in estuarine systems.

    EPA Science Inventory

    To understand their fate and transport in estuarine systems, the aggregation, sedimentation, and dissolution of CdSe quantum dots (QDs) in seawater were investigated. Hydrodynamic size increased from 40 to 60 nm to >1 mm within 1 h in seawater, and the aggregates were highly p...

  13. Toxicity ranking of estuarine sediments on the basis of Sparus aurata biomarkers.

    PubMed

    Cunha, Isabel; Neuparth, Teresa; Caeiro, Sandra; Costa, Maria Helena; Guilhermino, Lúcia

    2007-03-01

    Sparus aurata biomarkers were used to rank sediments from the Sado River estuary (Portugal) according to their toxicity. Initially, the activities of liver ethoxyresorufin-O-deethylase, liver and gill glutathione S-transferases, muscle lactate dehydrogenase, and brain acetylcholinesterase were tested in a laboratory bioassay with the reference compound benzo[a]pyrene. Enzymatic activities were determined in different tissues of fish exposed for 48, 96, or 240 h to three concentrations of benzo[a]pyrene (25, 50, and 100 microg/L). Induction of liver ethoxyresorufin-O-deethylase was observed at all the exposure periods and concentrations, suggesting a continuous response of this system to toxicant exposure. Induction of liver glutathione S-transferases activity was only observed after 240 h of exposure, whereas gill glutathione S-transferases activity was significantly inhibited at all the exposure periods, suggesting a direct or indirect effect of the toxicant on these enzymes. Inhibition of lactate dehydrogenases activity was only observed after 96 h of exposure to 25 microg/L of benzo[a]pyrene. No significant effects were observed on acetylcholinesterase activity, suggesting that cholinergic function of S. aurata is not affected by benzo[a]pyrene. In a second phase, fish were exposed for 240 h to sediments collected at five sites of the Sado River estuary, and the same biomarkers were analyzed. For all the enzymes assayed, significant differences among sites were found. In this study, the battery of biomarkers used allowed to discrimination among sites with different types of contamination, levels of contamination, or both, after multivariate data analysis. Discrimination of sites was similar to the ranking provided by a more complex and parallel study (including chemical analysis of sediments, macrobenthic community analysis, amphipod mortality toxicity tests, and sea urchin abnormality embryo assays), suggesting its suitability to evaluate the toxicity of

  14. Multi-level assessment of chronic toxicity of estuarine sediments with the amphipod Gammarus locusta: I. Biochemical endpoints.

    PubMed

    Neuparth, Teresa; Correia, Ana D; Costa, Filipe O; Lima, Gláucia; Costa, Maria Helena

    2005-07-01

    We report on biomarker responses conducted as part of a multi-level assessment of the chronic toxicity of estuarine sediments to the amphipod Gammarus locusta. A companion article accounts for organism and population-level effects. Five moderately contaminated sediments from two Portuguese estuaries, Sado and Tagus, were assessed. Three of them were muddy and two were sandy sediments. The objective was to assess sediments that were not acutely toxic. Three of the sediments met this criterion, the other two were diluted (50% and 75%) with clean sediment until acute toxicity was absent. Following 28-d exposures, the amphipods were analysed for whole-body metal bioaccumulation, metallothionein induction (MT), DNA strand breakage (SB) and lipid peroxidation (LP). Two of the muddy sediments did not cause chronic toxicity. These findings were consistent with responses at organism and population levels that showed higher growth rates and improvement of reproductive traits for amphipods exposed to these two sediments. Two other sediments, one muddy and one sandy, exhibited pronounced chronic toxicity, affecting SB, MT induction (in muddy sediment), survival and reproduction. Potential toxicants involved in these effects were identified. The last sandy sediment exhibited some loss of DNA integrity, however growth was also enhanced. Present results, together with the organism/population-level data, and also benthic communities information, were analysed under a weight-of-evidence approach. By providing evidence of exposure (or lack of it) to contaminants in sediments, the biomarkers here applied assisted in distinguishing toxicants' impacts in test organisms from the confounding influence of other geochemical features of the sediments.

  15. Benthic ciliate and meiofaunal communities in two contrasting habitats of an intertidal estuarine wetland

    NASA Astrophysics Data System (ADS)

    Du, Yongfen; Xu, Kuidong; Warren, Alan; Lei, Yanli; Dai, Renhai

    2012-05-01

    Annual variations in benthic meiofaunal and ciliated protozoan communities were investigated using monthly samplings from June 2006 to May 2007 in two habitats characterized by different vegetal coverage in an estuarine intertidal wetland of Qingdao Jiaozhou Bay, China. The sediment composition was stable at each site: sediments densely covered with seagrass (Suaeda glauca) in the lower estuarine site (Station S) were finer, with higher content of organic matter, phaeopigments and water than sediments at the upper estuarine site (Station S-P) which was unvegetated other than for patches of S. glauca and common reed (Phragmites australis). Chlorophyll a exhibited a similar distribution in the two habitats. A total of 14 meiofaunal groups, and 249 species of ciliates belonging to 37 genera, 28 families and 16 orders, were isolated from the two sites. Univariate and multivariate measures of the communities were significantly different between the two habitats. There were higher abundances of ciliates and meiofauna, and a greater diversity of ciliates, at Station S than Station S-P (223 vs. 61 species). Herbivorous ciliates were numerically predominant in ciliate communities at both sites. The representative ciliates at Station S-P belonged to the Cyrtophorida and appeared to be a reduced subset of the assemblage at Station S, which was characterized by members of the Prostomatida, Cyrtophorida, Hypotrichida and Scuticociliatida. More than 96% of the total meiofauna were nematodes, accounting for 93% of the differences in the abundance compositions of the meiofaunal communities between habitats. The average individual weights of nematodes were nearly 3 times greater at Station S than Station S-P, indicating a distinctive species composition at each site. Temperature, salinity and food availability were key factors that regulated the ciliate and meiofaunal community structure. Nematodes were the dominant group in terms of the combined abundance, biomass and benthic

  16. Mercury concentrations in estuarine sediments, Lavaca and Matagorda bays, Texas, 1992

    USGS Publications Warehouse

    Brown, David S.; Snyder, Grant L.; Taylor, R. Lynn

    1998-01-01

    U.S. Environmental Protection Agency Method 7471 (Cold Vapor Atomic Absorption) was an acceptable analytical method for determining the total mercury concentrations in the Lavaca-Matagorda Bays estuarine sediment samples. Measurement of additional trace metals would aid in the characterization of total mercury concentrations and in the identification of concentrator/collector relations that are principally responsible for the adsorption of mercurous compounds to particulates in the bottom sediments.

  17. Uranium geochemistry in estuarine sediments: Controls on removal and release processes

    SciTech Connect

    Barnes, C.E.; Cochran, J.K. )

    1993-02-01

    Porewater uranium profiles from Long Island Sound (LIS) and Amazon shelf sediments and LIS sediment incubation experiments indicate that both removal and release processes control U geochemistry in estuarine sediments. Release of U from sediments occurs in association with Fe reduction. A correlation between U and Fe (and Mn) observed in sediment incubation experiments suggests that there is release of U from Fe-Mn-oxides as they are reduced, consistent with data from the Amazon shelf. In both sediment porewater profiles (LIS and Amazon) and sediment incubation experiments (LIS), there is removal of U from porewater under conditions of sulfate reduction. Sediment incubation experiments indicate that the removal rate is first-order with respect to U concentration, and the rate constant is linearly correlated to sulfate reduction rates. The link between U removal and sulfate reduction (a measure of diagenetic microbial activity) is consistent with a microbial mediation of U reduction. The diffusion flux of U into LIS sediments is estimated from porewater profiles. The inclusion of this estuarine removal term in the oceanic U balance increases the importance of the sediment sink. 62 refs., 12 figs., 2 tabs.

  18. Trace element release from estuarine sediments of South Mosquito Lagoon near Kennedy Space Center

    NASA Technical Reports Server (NTRS)

    Menon, M. P.; Ghuman, G. S.; Emeh, C. O.

    1979-01-01

    Analytical partitioning of four trace metals in estuarine sediments collected from eight sites in South Mosquito Lagoon near Kennedy Space Center, in terms of four different categories was accomplished using four different extraction techniques. The concentrations of the four trace metals, Zn, Mn, Cd, and Cu, released in interstitial water extract, 1 N ammonium acetate extract, conc. HCl extract and fusion extract of sediments as well as their concentrations in water samples collected from the same location were determined using flame atomic absorption technique. From the analytical results the percentages of total amount of each metal distributed among four different categories, interstitial water phase, acetate extractable, acid extractable and detrital crystalline material, were determined. Our results suggest that analytical partitioning of trace metals in estuarine sediments may be used to study the mechanism of incorporation of trace metals with sediments from natural waters. A correlation between the seasonal variation in the concentration of acetate extractable trace metals in the sediment and similar variation in their concentration in water was observed. A mechanism for the release of trace metals from estuarine sediments to natural water is also suggested.

  19. Fish community responses to green tides in shallow estuarine and coastal areas

    NASA Astrophysics Data System (ADS)

    Le Luherne, E.; Réveillac, E.; Ponsero, A.; Sturbois, A.; Ballu, S.; Perdriau, M.; Le Pape, O.

    2016-06-01

    All over the world, numerous bays and estuarine systems that are known to shelter essential fish habitats are experiencing proliferations of green macroalgae known as green tides. Although the processes that enhance green tides in response to nutrient enrichment are well known, their consequences for ecological communities -especially for ichthyofauna- remain poorly studied. To estimate these consequences, this analysis focused on the two types of shallow systems that are experiencing green tides: sandy beaches and estuarine mudflats. In these two systems, macroalgae proliferation and fish community were surveyed along seasonal cycles at control and impacted sites that shared similar physico-chemical parameters and sediment structure. To analyse the consequences of green tides on the fish community, a Before-After Control-Impact approach was used. This approach reveals no difference between fish communities at the control and impacted sites before the macroalgal bloom. Then, it underlines an influence of green tides on the fish community, and this influence varies according to the composition, density and duration of the macroalgal bloom. Indeed, when intertidal systems experienced short proliferation and/or weak density, green tides did not seem to impact the fish community. However, when green macroalgae proliferated in large quantities and/or when the proliferation lasted for long periods, the fish community was significantly affected. These modifications in the fish community led to a significant decrease in fish species diversity and density until fish disappeared from impacted sites at high proliferations. Furthermore, the response of fish species to green tides differed according to their functional guilds. Negative consequences for benthic and marine juvenile fish species were beginning at low proliferations, whereas for pelagic fish species they occurred only at high proliferations. Thus, green tides significantly affect fish habitat suitability because

  20. Fluvio-estuarine sedimentation and estuarine evolution during the Late-Holocene in the Taw Estuary, England: response to relative sea-level and climate change

    NASA Astrophysics Data System (ADS)

    Havelock, G. M.; Brown, T. G.

    2010-12-01

    Present models of Holocene estuary evolution are driven largely by changes in relative sea-level (RSL) with little reference to long-term changes in fluvial regime and regional climate. Centennial-scale climate change has been shown to have a major control on Holocene river behaviour, with fluvial records showing evidence for a high sensitivity of flood occurrence to changing climate. It follows that the changes in river discharge associated with these climatic fluctuations should have an important bearing on inner estuarine hydrology and sedimentology. Indeed, recent US studies have shown that changes in freshwater inflow can be inferred by changes in estuarine paleosalinity and that the timing of these events reflect changes in regional precipitation. Deposition in the transitional inner estuarine environment can therefore be seen to be controlled by both marine and fluvial influences. The fluvio-estuarine late-Holocene sedimentary record was investigated in the macro-tidal Taw Estuary, south-west England in order to ascertain the relative importance of changes in RSL and precipitation driven river discharge on estuarine sedimentation and centennial-scale geomorphic evolution. The inner estuarine record was compared with a local RSL reconstruction for the Taw Estuary and with a reconstructed Holocene flood record and geomorphic fluvial history for the lower Taw valley. The diatom record of numerous sediment cores enabled paleosalinity to be evaluated. The fluvio-estuarine valley fill was split into a series of stratigraphic units, with a chronological framework derived using radiocarbon and OSL dating methods. Geomorphic change in the inner estuarine zone is shown to be mainly influenced by phases of increased river discharge and catchment precipitation, with fluvial instability translating down river into the inner estuarine system. This results in periods of enhanced tidal channel migration, marsh-floodplain formation and estuarine channel-bed aggradation

  1. Use of Sediment Risk and Ecological/Conservation Value for Strategic Management of Estuarine Environments: Sydney Estuary, Australia

    NASA Astrophysics Data System (ADS)

    Birch, Gavin F.; Hutson, Philip

    2009-10-01

    Sediment mantling the floor of Sydney estuary contains a wide range of chemicals at highly elevated concentrations over extensive areas. Appropriate sediment management decisions are urgently required to prevent further degradation of sediment quality and to minimize resulting adverse ecological effects. The objective of the present work was to provide a systematic, estuary-wide assessment of sediment risk and ecological/conservation value throughout the harbor to guide sediment management decisions. Sediment risk is the likelihood of sediment chemistry causing adverse biological effects to bottom-dwelling animals and was conducted using national sediment quality guidelines (SQGs) for single contaminants and the mean SQG quotient approach to assess chemical mixtures. Sediment risk was negligible at the mouth of the estuary, but increased strongly landwards. The ecological/conservation value assessment was conducted to identify sites that warrant different levels of protection and was conducted using the value of ecological communities and priority waterway use. Consideration of these two parameters combined enabled the estuary to be prioritized for management attention. The prioritization and identification of appropriate management strategies were determined through the use of management matrices also based on sediment risk and ecological/conservation value. A computer package is being developed to provide managers with information on sediment risk, ecological/conservation value, the urgency and the type of management intervention required for any location in Sydney estuary, in real-time. This approach to estuarine management is unique and will greatly improve effective management of Sydney estuary, and other harbors in urgent need of management action and protection.

  2. Decadal-timescale estuarine geomorphic change under future scenarios of climate and sediment supply

    USGS Publications Warehouse

    Ganju, N.K.; Schoellhamer, D.H.

    2010-01-01

    Future estuarine geomorphic change, in response to climate change, sea-level rise, and watershed sediment supply, may govern ecological function, navigation, and water quality. We estimated geomorphic changes in Suisun Bay, CA, under four scenarios using a tidal-timescale hydrodynamic/sediment transport model. Computational expense and data needs were reduced using the morphological hydrograph concept and the morphological acceleration factor. The four scenarios included (1) present-day conditions; (2) sea-level rise and freshwater flow changes of 2030; (3) sea-level rise and decreased watershed sediment supply of 2030; and (4) sea-level rise, freshwater flow changes, and decreased watershed sediment supply of 2030. Sea-level rise increased water levels thereby reducing wave-induced bottom shear stress and sediment redistribution during the wind-wave season. Decreased watershed sediment supply reduced net deposition within the estuary, while minor changes in freshwater flow timing and magnitude induced the smallest overall effect. In all future scenarios, net deposition in the entire estuary and in the shallowest areas did not keep pace with sea-level rise, suggesting that intertidal and wetland areas may struggle to maintain elevation. Tidal-timescale simulations using future conditions were also used to infer changes in optical depth: though sea-level rise acts to decrease mean light irradiance, decreased suspended-sediment concentrations increase irradiance, yielding small changes in optical depth. The modeling results also assisted with the development of a dimensionless estuarine geomorphic number representing the ratio of potential sediment import forces to sediment export forces; we found the number to be linearly related to relative geomorphic change in Suisun Bay. The methods implemented here are widely applicable to evaluating future scenarios of estuarine change over decadal timescales. ?? The Author(s) 2009.

  3. Shifts in the community structure and activity of anaerobic ammonium oxidation bacteria along an estuarine salinity gradient

    NASA Astrophysics Data System (ADS)

    Zheng, Yanling; Jiang, Xiaofen; Hou, Lijun; Liu, Min; Lin, Xianbiao; Gao, Juan; Li, Xiaofei; Yin, Guoyu; Yu, Chendi; Wang, Rong

    2016-06-01

    Anaerobic ammonium oxidation (anammox) is a major microbial pathway for nitrogen (N) removal in estuarine and coastal environments. However, understanding of anammox bacterial dynamics and associations with anammox activity remains scarce along estuarine salinity gradient. In this study, the diversity, abundance, and activity of anammox bacteria, and their potential contributions to total N2 production in the sediments along the salinity gradient (0.1-33.8) of the Yangtze estuarine and coastal zone, were studied using 16S rRNA gene clone library, quantitative polymerase chain reaction assay, and isotope-tracing technique. Phylogenetic analysis showed a significant change in anammox bacterial community structure along the salinity gradient (P < 0.01), with the dominant genus shifting from Brocadia in the freshwater region to Scalindua in the open ocean. Anammox bacterial abundance ranged from 3.67 × 105 to 8.22 × 107 copies 16S rRNA gene g-1 and related significantly with salinity (P < 0.05). The anammox activity varied between 0.08 and 6.46 nmol N g-1 h-1 and related closely with anammox bacterial abundance (P < 0.01). Contributions of anammox activity to total N loss were highly variable along the salinity gradient, ranging from 5 to 77% and were significantly negatively correlated with salinity (P < 0.01). Sediment organic matter was also recognized as an important factor in controlling the relative role of anammox to total N2 production in the Yangtze estuarine and coastal zone. Overall, our data demonstrated a biogeographical distribution of anammox bacterial diversity, abundance, and activity along the estuarine salinity gradient and suggested that salinity is a major environmental control on anammox process in the estuarine and coastal ecosystems.

  4. Chlorinated and polycyclic aromatic hydrocarbons in riverine and estuarine sediments from Pearl River Delta, China.

    PubMed

    Mai, Bi-Xian; Fu, Jia-Mo; Sheng, Guo-Ying; Kang, Yue-Hui; Lin, Zheng; Zhang, Gan; Min, Yu-Shuan; Zeng, Eddy Y

    2002-01-01

    Spatial distribution of chlorinated hydrocarbons [chlorinated pesticides (CPs) and polychlorinated biphenyls (PCBs)] and polycyclic aromatic hydrocarbons (PAHs) was measured in riverine and estuarine sediment samples from Pearl River Delta, China, collected in 1997. Concentrations of CPs of the riverine sediment samples range from 12 to 158 ng/g, dry weight, while those of PCBs range from 11 to 486 ng/g. The CPs concentrations of the estuarine sediment samples are in the range 6-1658 ng/g, while concentrations of PCBs are in the range 10-339 ng/g. Total PAH concentration ranges from 1168 to 21,329 ng/g in the riverine sediment samples, whereas the PAH concentration ranges from 323 to 14,812 ng/g in the sediment samples of the Estuary. Sediment samples of the Zhujiang River and Macao harbor around the Estuary show the highest concentrations of CPs, PCBs, and PAHs. Possible factors affecting the distribution patterns are also discussed based on the usage history of the chemicals, hydrologic condition, and land erosion due to urbanization processes. The composition of PAHs is investigated and used to assess petrogenic, combustion and naturally derived PAHs of the sediment samples of the Pearl River Delta. In addition, the concentrations of a number of organic compounds of the Pearl River Delta samples indicate that sediments of the Zhujiang river and Macao harbor are most likely to pose biological impairment.

  5. Modelling of cohesive sediment dynamics in tidal estuarine systems: Case study of Tagus estuary, Portugal

    NASA Astrophysics Data System (ADS)

    Franz, G.; Pinto, L.; Ascione, I.; Mateus, M.; Fernandes, R.; Leitão, P.; Neves, R.

    2014-12-01

    Cohesive sediment dynamics in estuarine systems is a major issue in water quality and engineering problems. Numerical models can help to assess the complex dynamics of cohesive sediments, integrating the information collected in monitoring studies. Following a numerical approach we investigated the main factors that influence the cohesive sediment dynamics in an estuarine system composed of large mudflats (Tagus estuary, Portugal). After a spin up period of the bottom layer and considering the combined effect of waves and currents on the bottom shear stress, the dynamics of cohesive sediment during the fortnightly and daily erosion-sedimentation cycle was properly reproduced by the model. The results of cohesive suspended sediments were validated with data from sixteen monitoring stations located along the estuary and turbidity data measured by two multiparametric probes. The hydrodynamics were previously validated by harmonic analysis and with ADCP data. Although tidal currents are the major cause of cohesive sediment erosion, the results suggest that wind waves also play an important role. The simulated sediment mass involved in the fortnightly tidal cycle was in the same order of magnitude of the annual load from the rivers, as observed in previous studies based on field data.

  6. Effect of sediment properties on the sorption of C12-2-LAS in marine and estuarine sediments.

    PubMed

    Rico-Rico, Angeles; Temara, Ali; Behrends, Thilo; Hermens, Joop L M

    2009-02-01

    Linear alkylbenzene sulfonates (LAS) are anionic high production volume surfactants used in the manufacture of cleaning products. Here, we have studied the effect of the characteristics of marine and estuarine sediments on the sorption of LAS. Sorption experiments were performed with single sediment materials (pure clays and sea sand), with sediments treated to reduce their organic carbon content, and with field marine and estuarine sediments. C12-2-LAS was used as a model compound. Sorption to the clays montmorillonite and kaolinite resulted in non-linear isotherms very similar for both clays. When reducing the organic content, sorption coefficients decreased proportionally to the fraction removed in fine grain sediments but this was not the case for the sandy sediment. The correlation of the sediment characteristics with the sorption coefficients at different surfactant concentrations showed that at concentrations below 10 microg C12-2-LAS/L, the clay content correlated better with sorption, while the organic fraction became more significant at higher concentrations.

  7. Distribution, magnitude and characterization of the toxicity of Ukrainian estuarine sediments.

    PubMed

    Burgess, Robert M; Konovets, Igor M; Kipnis, Ludmila S; Lyashenko, Artem V; Grintsov, Vladimir A; Petrov, Alexei N; Terletskaya, Anna V; Milyukin, Mykhailo V; Povolotskii, Mark I; Demchenko, Victor Y; Bogoslovskaya, Tatiyana A; Topkin, Yuri V; Vorobyova, Tatiyana V; Portis, Lisa M; Ho, Kay T

    2011-11-01

    During the Soviet era, Ukraine was an important industrial and agricultural region of the Soviet Union. This industrial and agricultural activity resulted in contamination of Ukraine's estuaries with legacy anthropogenic pollutants. Investigations on the toxicological effects of this estuarine contamination have been limited. For this research, we measured the toxicity of contaminated sediments from four Ukrainian estuaries to several aquatic organisms over 3 years. Sediment chemical analyses and whole sediment toxicity identification evaluations (TIEs) were also performed to determine the classes of contaminants contributing to toxicity. Toxic sediments were observed in several of the Ukrainian estuaries and chemical analyses of the sediments demonstrated anthropogenic contaminants were widely distributed. Contaminants were also detected in macrobenthic organisms collected from the sediments. Several lines of evidence, including TIEs, indicated hydrophobic organic chemicals (HOCs) were contributing substantially to observed toxicity. This information can guide environmental managers to prioritize portions of the estuaries requiring remediation. Published by Elsevier Ltd.

  8. Method 440.0 Determination of Carbon and Nitrogen in Sediments and Particulatesof Estuarine/Coastal Waters Using Elemental Analysis

    EPA Science Inventory

    Elemental analysis is used to determine particulate carbon (PC) and particulate nitrogen (PN) in estuarine and coastal waters and sediment. The method measures the total carbon and nitrogen irrespective of source (inorganic or organic).

  9. Method 440.0 Determination of Carbon and Nitrogen in Sediments and Particulatesof Estuarine/Coastal Waters Using Elemental Analysis

    EPA Science Inventory

    Elemental analysis is used to determine particulate carbon (PC) and particulate nitrogen (PN) in estuarine and coastal waters and sediment. The method measures the total carbon and nitrogen irrespective of source (inorganic or organic).

  10. Holocene estuarine sediments as a source of arsenic in Pleistocene groundwater in suburbs of Hanoi, Vietnam

    NASA Astrophysics Data System (ADS)

    Kuroda, Keisuke; Hayashi, Takeshi; Funabiki, Ayako; Do, An Thuan; Canh, Vu Duc; Nga, Tran Thi Viet; Takizawa, Satoshi

    2017-06-01

    Groundwater pollution by arsenic is a major health threat in suburban areas of Hanoi, Vietnam. The present study evaluates the effect of the sedimentary environments of the Pleistocene and Holocene deposits, and the recharge systems, on the groundwater arsenic pollution in Hanoi suburbs distant from the Red River. At two study sites (Linh Dam and Tai Mo communes), undisturbed soil cores identified a Pleistocene confined aquifer (PCA) and Holocene unconfined aquifer (HUA) as major aquifers, and Holocene estuarine and deltaic sediments as an aquitard layer between the two aquifers. The Holocene estuarine sediments (approximately 25-40 m depth, 9.6-4.8 cal ka BP) contained notably high concentrations of arsenic and organic matter, both likely to have been accumulated by mangroves during the Holocene sea-level highstand. The pore waters in these particular sediments exhibited elevated levels of arsenic and dissolved organic carbon. Arsenic in groundwater was higher in the PCA (25-94 μg/L) than in the HUA (5.2-42 μg/L), in both the monitoring wells and neighboring household tubewells. Elevated arsenic concentration in the PCA groundwater was likely due to vertical infiltration through the arsenic-rich and organic-matter-rich overlying Holocene estuarine sediments, caused by massive groundwater abstraction from the PCA. Countermeasures to prevent arsenic pollution of the PCA groundwater may include seeking alternative water resources, reducing water consumption, and/or appropriate choice of aquifers for groundwater supply.

  11. Holocene estuarine sediments as a source of arsenic in Pleistocene groundwater in suburbs of Hanoi, Vietnam

    NASA Astrophysics Data System (ADS)

    Kuroda, Keisuke; Hayashi, Takeshi; Funabiki, Ayako; Do, An Thuan; Canh, Vu Duc; Nga, Tran Thi Viet; Takizawa, Satoshi

    2017-01-01

    Groundwater pollution by arsenic is a major health threat in suburban areas of Hanoi, Vietnam. The present study evaluates the effect of the sedimentary environments of the Pleistocene and Holocene deposits, and the recharge systems, on the groundwater arsenic pollution in Hanoi suburbs distant from the Red River. At two study sites (Linh Dam and Tai Mo communes), undisturbed soil cores identified a Pleistocene confined aquifer (PCA) and Holocene unconfined aquifer (HUA) as major aquifers, and Holocene estuarine and deltaic sediments as an aquitard layer between the two aquifers. The Holocene estuarine sediments (approximately 25-40 m depth, 9.6-4.8 cal ka uc(BP)) contained notably high concentrations of arsenic and organic matter, both likely to have been accumulated by mangroves during the Holocene sea-level highstand. The pore waters in these particular sediments exhibited elevated levels of arsenic and dissolved organic carbon. Arsenic in groundwater was higher in the PCA (25-94 μg/L) than in the HUA (5.2-42 μg/L), in both the monitoring wells and neighboring household tubewells. Elevated arsenic concentration in the PCA groundwater was likely due to vertical infiltration through the arsenic-rich and organic-matter-rich overlying Holocene estuarine sediments, caused by massive groundwater abstraction from the PCA. Countermeasures to prevent arsenic pollution of the PCA groundwater may include seeking alternative water resources, reducing water consumption, and/or appropriate choice of aquifers for groundwater supply.

  12. Effects-based spatial assessment of contaminated estuarine sediments from Bear Creek, Baltimore Harbor, MD, USA.

    PubMed

    Hartzell, Sharon E; Unger, Michael A; McGee, Beth L; Yonkos, Lance T

    2017-07-15

    Estuarine sediments in regions with prolonged histories of industrial activity are often laden to significant depths with complex contaminant mixtures, including trace metals and persistent organic pollutants. Given the complexity of assessing risks from multi-contaminant exposures, the direct measurement of impacts to biological receptors is central to characterizing contaminated sediment sites. Though biological consequences are less commonly assessed at depth, laboratory-based toxicity testing of subsurface sediments can be used to delineate the scope of contamination at impacted sites. The extent and depth of sediment toxicity in Bear Creek, near Baltimore, Maryland, USA, was delineated using 10-day acute toxicity tests with the estuarine amphipod Leptocheirus plumulosus, and chemical analysis of trace metals and persistent organic pollutants. A gradient of toxicity was demonstrated in surface sediments with 21 of 22 tested sites differing significantly from controls. Effects were most pronounced (100% lethality) at sites proximate to a historic industrial complex. Sediments from eight of nine core samples to depths of 80 cm were particularly impacted (i.e., caused significant lethality to L. plumulosus) even in locations overlain with relatively non-toxic surface sediments, supporting a conclusion that toxicity observed at the surface (top 2 cm) does not adequately predict toxicity at depth. In seven of nine sites, toxicity of surface sediments differed from toxicity at levels beneath by 28 to 69%, in five instances underestimating toxicity (28 to 69%), and in two instances overestimating toxicity (44 to 56%). Multiple contaminants exceeded sediment quality guidelines and correlated positively with toxic responses within surface sediments (e.g., chromium, nickel, polycyclic aromatic hydrocarbon (PAH), total petroleum hydrocarbon). Use of an antibody-based PAH biosensor revealed that porewater PAH concentrations also increased with depth at most sites. This

  13. Nitrogen fixing bacterial diversity in a tropical estuarine sediments.

    PubMed

    Thajudeen, Jabir; Yousuf, Jesmi; Veetil, Vipindas Puthiya; Varghese, Sherin; Singh, Arvind; Abdulla, Mohamed Hatha

    2017-02-01

    Microorganisms play a significant role in biogeochemical cycles, especially in the benthic and pelagic ecosystems. Role of environmental parameters in regulating the diversity, distribution and physiology of these microorganisms in tropical marine environment is not well understood. In this study, we have identified dinitrogen (N2) fixing bacterial communities in the sediments by constructing clone libraries of nitrogenase (nifH) gene from four different stations in the Cochin estuary, along the southeastern Arabian Sea. N2 fixing bacterial clones revealed that over 20 putative diazotrophs belong to alpha-, beta-, gamma-, delta- and epsilon- proteobacteria and firmicutes. Predominant genera among these were Bradyrhizobium sp. (α-proteobacteria), Dechloromonas sp. (β-proteobacteria); Azotobactor sp., Teredinibacter sp., Methylobacter sp., Rheinheimera sp. and Marinobacterium sp. (γ-proteobacteria); Desulfobacter sp., Desulfobulbus sp. and Desulfovibrio sp. (δ -proteobacteria); Arcobacter sp. and Sulfurospirillum sp. (ε-proteobacteria). Nostoc sp. was solely identified among the cyanobacterial phylotype. Nitrogen fixing Sulfate reducing bacteria (SRBs) such as Desulfobulbus sp., Desulfovibrio sp., Desulfuromonas sp., Desulfosporosinus sp., Desulfobacter sp., were also observed in the study. Most of the bacterial nifH sequences revealed that the identities of N2 fixing bacteria were less than 95% similar to that available in the GenBank database, which suggested that the sequences were of novel N2 fixing microorganisms. Shannon-Weiner diversity index of nifH gene ranged from 2.95 to 3.61, indicating an inflated diversity of N2 fixing bacteria. Canonical correspondence analysis (CCA) implied positive correlation among nifH diversity, N2 fixation rate and other environmental variables.

  14. Escherichia coli and fecal coliforms in freshwater and estuarine sediments

    USDA-ARS?s Scientific Manuscript database

    It has been known for some time that substantial populations of fecal coliforms and E. coli are harbored in freshwater bottom sediments, bank soils, and beach sands. However, the relative importance of sediments as bacterial habitats and as a source of water-borne fecal coliforms and E. coli has not...

  15. Dynamics of mercury species in surface sediments of a macrotidal estuarine-coastal system (Adour River, Bay of Biscay)

    NASA Astrophysics Data System (ADS)

    Stoichev, T.; Amouroux, D.; Wasserman, J. C.; Point, D.; De Diego, A.; Bareille, G.; Donard, O. F. X.

    2004-03-01

    Estuarine and coastal surface sediments from the Adour estuary and adjacent coastal area (South Bay of Biscay) have been investigated to establish mercury species variability in a macrotidal system submitted to contrasted seasonal river discharges and downstream urbanisation. Surface sediments were sampled during three campaigns in the major sediment deposits of the Adour estuary and at selected discharge points. Concentrations of Hg 2+ and MeHg + in Adour estuarine sediments average 1600 and 1.3 pmol g -1, and range from <2 to 7300 pmol g -1 and from <0.5 to 8.0 pmol g -1, respectively. The concentrations of inorganic ionic mercury (Hg 2+) and monomethylmercury (MeHg +) in the surface sediments display large seasonal variation, being one order of magnitude higher in June 2001 for Hg 2+ and in October 2000 for MeHg +. The results show that Hg 2+ can be accumulated in the estuarine sediments after seasonal river inputs and both remobilised and methylated during dry period. Mercury species concentrations in coastal sediments collected in June 2001 assessed the impact of estuarine inputs on the nearby coastal area. Except direct anthropogenic discharge points, the variability and transfer of Hg 2+ and MeHg + in surface sediments of the whole estuarine-coastal macrotidal system can be depicted by simple geochemical parameters of the bulk sediments, such as grain size distribution, organic carbon and total sulphur.

  16. Arsenic Environmental Threshold Surpass in Estuarine Sediments: Effects of Bioturbation.

    PubMed

    Costa, L; Mirlean, N; Garcia, F

    2017-04-01

    We investigate the distributions of the metalloid arsenic (As) and metals iron (Fe) and manganese (Mn) in the sediments of two pristine areas of a biological reserve in the Patos Lagoon Estuary. This area is occupied by Spartina alterniflora and by Neohelice granulata crab colonies and low concentrations of As are expected. The bioturbation/bioirrigation of sediments by crabs and the roots of plants lead to the penetration of oxygen below the oxic/suboxix division and the subsequent precipitation of Fe-Mn hydroxides. Ferruginous incrustations and nodules along roots and crab channels propagate to depths of over 35 cm and sediment contains up to 33 mg kg(- 1) of As. The metalloid distribution in sediments is strongly correlated with that of Fe but not with Mn. This study revealed that areas with biologically disturbed sediments could demonstrate contamination in As, which is not anthropogenic in origin.

  17. Iron monosulfide accumulation and pyrite formation in eutrophic estuarine sediments

    NASA Astrophysics Data System (ADS)

    Kraal, Peter; Burton, Edward D.; Bush, Richard T.

    2013-12-01

    This study investigates iron (Fe) and sulfur (S) cycling in sediments from the eutrophic Peel-Harvey Estuary in Western Australia, which is subject to localized accumulation of strongly reducing, organic- and sulfide-rich sediments. Sedimentary iron was mostly present in highly reactive form (on average 73% of total Fe) and showed extensive sulfidization even in surface sediments, despite being overlain by a well-mixed oxygenated water column. This indicates that, under eutrophic marine conditions, Fe sulfidization may be driven by reductive processes in the sediment without requiring oxygen depletion in the overlying waters. Strong enrichments in iron monosulfide (FeS > 300 μmol g-1) were observed in fine-grained sediment intervals up to 45 cm depth. This metastable Fe sulfide is commonly restricted to thin subsurface sediment intervals, below which pyrite (FeS2) dominates. Our findings suggest inhibition of the dissolution-precipitation processes that replace FeS with FeS2 in sediments. Rates of pyrite formation based on the FeS2 profiles were much lower than those predicted by applying commonly used kinetic equations for pyrite formation. Dissolved H2S was present at millimolar levels throughout the investigated sediment profiles. This may indicate that (i) pyrite formation via reaction between dissolved Fe (including Fe clusters) and H2S was limited by low availability of dissolved Fe or (ii) reaction kinetics of pyrite formation via the H2S pathway may be relatively slow in natural reducing sediments. We propose that rapid burial of the FeS under anoxic conditions in these organic-rich reducing sediments minimizes the potential for pyrite formation, possibly by preventing dissolution of FeS or by limiting the availability of oxidized sulfur species that are required for pyrite formation via the polysulfide pathway.

  18. Suspended sediment transport under estuarine tidal channel conditions

    USGS Publications Warehouse

    Sternberg, R.W.; Kranck, K.; Cacchione, D.A.; Drake, D.E.

    1988-01-01

    A modified version of the GEOPROBE tripod has been used to monitor flow conditions and suspended sediment distribution in the bottom boundary layer of a tidal channel within San Francisco Bay, California. Measurements were made every 15 minutes over three successive tidal cycles. They included mean velocity profiles from four electromagnetic current meters within 1 m of the seabed; mean suspended sediment concentration profiles from seven miniature nephelometers operated within 1 m of the seabed; near-bottom pressure fluctuations; vertical temperature gradient; and bottom photographs. Additionally, suspended sediment was sampled from four levels within 1 m of the seabed three times during each successive flood and ebb cycle. While the instrument was deployed, STD-nephelometer measurements were made throughout the water column, water samples were collected each 1-2 hours, and bottom sediment was sampled at the deployment site. From these measurements, estimates were made of particle settling velocity (ws) from size distributions of the suspended sediment, friction velocity (U*) from the velocity profiles, and reference concentration (Ca) was measured at z = 20 cm. These parameters were used in the suspended sediment distribution equations to evaluate their ability to predict the observed suspended sediment profiles. Three suspended sediment particle conditions were evaluated: (1) individual particle size in the 4-11 ?? (62.5-0.5 ??m) range with the reference concentration Ca at z = 20 cm (C??), (2) individual particle size in the 4-6 ?? size range, flocs representing the 7-11 ?? size range with the reference concentration Ca at z = 20 cm (Cf), and (3) individual particle size in the 4-6 ?? size range, flocs representing the 7-11 ?? size range with the reference concentration predicted as a function of the bed sediment size distribution and the square of the excess shear stress. In addition, computations of particle flux were made in order to show vertical variations

  19. Biochemical Mechanisms and Microorganisms Involved in Anaerobic Testosterone Metabolism in Estuarine Sediments

    PubMed Central

    Shih, Chao-Jen; Chen, Yi-Lung; Wang, Chia-Hsiang; Wei, Sean T.-S.; Lin, I-Ting; Ismail, Wael A.; Chiang, Yin-Ru

    2017-01-01

    Current knowledge on the biochemical mechanisms underlying microbial steroid metabolism in anaerobic ecosystems is extremely limited. Sulfate, nitrate, and iron [Fe (III)] are common electron acceptors for anaerobes in estuarine sediments. Here, we investigated anaerobic testosterone metabolism in anaerobic sediments collected from the estuary of Tamsui River, Taiwan. The anaerobic sediment samples were spiked with testosterone (1 mM) and individual electron acceptors (10 mM), including nitrate, Fe3+, and sulfate. The analysis of androgen metabolites indicated that testosterone biodegradation under denitrifying conditions proceeds through the 2,3-seco pathway, whereas testosterone biodegradation under iron-reducing conditions may proceed through an unidentified alternative pathway. Metagenomic analysis and PCR-based functional assays suggested that Thauera spp. were the major testosterone degraders in estuarine sediment samples incubated with testosterone and nitrate. Thauera sp. strain GDN1, a testosterone-degrading betaproteobacterium, was isolated from the denitrifying sediment sample. This strain tolerates a broad range of salinity (0–30 ppt). Although testosterone biodegradation did not occur under sulfate-reducing conditions, we observed the anaerobic biotransformation of testosterone to estrogens in some testosterone-spiked sediment samples. This is unprecedented since biotransformation of androgens to estrogens is known to occur only under oxic conditions. Our metagenomic analysis suggested that Clostridium spp. might play a role in this anaerobic biotransformation. These results expand our understanding of microbial metabolism of steroids under strictly anoxic conditions. PMID:28848528

  20. Lipid biomarkers and organic matter carbon isotopes in estuarine sediments as proxies for evaluating seawater intrusion

    NASA Astrophysics Data System (ADS)

    Gong, Weiming; Zhang, Zhaohui

    2015-03-01

    Coastal wetlands and estuarine sediments are characteristics of tide-dominated environments and retain a record of seawater intrusion and possibly sea-level changes. A variety of methods including the C/N ratio and δ13C of bulk organic matter in the sediment have been employed in estuarine studies, but they are generally non-specific indicators. Here we report using lipid biomarkers to evaluate the extent of seawater intrusion based on an estuary in eastern China, Xinyanggang. Along the river from the estuary mouth upstream to the freshwater head, the vegetation shifts quickly from salt-tolerant Spartina (C4) to the less tolerant reed Phragmites (C3), both of which have distinguished δ13C values and biomarker distribution. The δ13C values of particulate organic matter (POM) and surface sediment decreased from the estuary mouth upstream, indicating the reduced contributions from Spartina and marine phytoplankton to the POM and surface sediment and increased inputs from Phragmites. The C32/C30 alkanol and cholesterol/sitosterol ratio decreased in the surface sediments, faithfully recording the variations in the contributions from Spartina and Phragmites. The combination of biomarker distribution and organic matter δ13C in the sediments can be used as indicators for sea water intrusion into the estuary/river.

  1. Requirements for modeling trace metal partitioning in oxidized estuarine sediments

    USGS Publications Warehouse

    Luoma, S.N.; Davis, J.A.

    1983-01-01

    The fate of particulate-bound metals is of particular importance in estuaries because major biological energy flows involve consumption of detrital particles. The biological impact of particulate-bound metals is strongly influenced by the partitioning of metals among sediment components at the oxidized sediment-water interface. Adequate methods for directly measuring this partitioning are not available, thus a modeling approach may be most useful. Important requirements for such a model include: (1) determinations of metal binding intensities which are comparable among sediment components important in oxidized sediments; (2) comparable determinations of the binding capacities of the several forms of each component; (3) operational determinations of the abundance in natural sediments of components of defined binding capacity; (4) assessments of the influence of particle coatings and multicomponent aggregation on the available binding capacity of each substrate; (5) consideration of the effect of Ca and Mg competition on binding to different components; and (6) determinations of the kinetics of metal redistribution among components in oxidized sediments. ?? 1983.

  2. Methanogenesis and sulfate reduction: Competitive and noncompetitive substrates in estuarine sediments

    USGS Publications Warehouse

    Oremland, Ronald S.; Polcin, Sandra

    1982-01-01

    Sulfate ions did not inhibit methanogenesis in estuarine sediments supplemented with methanol, trimethylamine, or methionine. However, sulfate greatly retarded methanogenesis when hydrogen or acetate was the substrate. Sulfate reduction was stimulated by acetate, hydrogen, and acetate plus hydrogen, but not by methanol or trimethylamine. These results indicate that sulfate-reducing bacteria will outcompete methanogens for hydrogen, acetate, or both, but will not compete with methanogens for compounds like methanol, trimethylamine, or methionine, thereby allowing methanogenesis and sulfate reduction to operate simultaneously within anoxic, sulfate-containing sediments.

  3. Optimal estuarine sediment monitoring network design with simulated annealing.

    PubMed

    Nunes, L M; Caeiro, S; Cunha, M C; Ribeiro, L

    2006-02-01

    An objective function based on geostatistical variance reduction, constrained to the reproduction of the probability distribution functions of selected physical and chemical sediment variables, is applied to the selection of the best set of compliance monitoring stations in the Sado river estuary in Portugal. These stations were to be selected from a large set of sampling stations from a prior field campaign. Simulated annealing was chosen to solve the optimisation function model. Both the combinatorial problem structure and the resulting candidate sediment monitoring networks are discussed, and the optimal dimension and spatial distribution are proposed. An optimal network of sixty stations was obtained from an original 153-station sampling campaign.

  4. Sublethal effects of the antibiotic tylosin on estuarine benthic microalgal communities.

    PubMed

    Pinckney, James L; Hagenbuch, Isaac M; Long, Richard A; Lovell, Charles R

    2013-03-15

    Pharmaceuticals are common chemical contaminants in estuaries receiving effluent from wastewater and sewage treatment facilities. The purpose of this research was to examine benthic microalgal (BMA) community responses to sublethal exposures to tylosin, a common and environmentally persistent antibiotic. Bioassays, using concentrations of 0.011-218 μmol tylosin l(-1), were performed on intertidal muddy sediments from North Inlet Estuary, SC. Exposure to tylosin resulted in a reduction in total BMA biomass and primary productivity. Furthermore, exposure seemed to retard diatom growth while having a minimal effect on cyanobacteria biomass. Estuarine systems receiving chronic inputs of trace concentrations of tylosin, as well as other antibiotics, may experience significant reductions in BMA biomass and primary productivity. Given the well-documented role of BMA in the trophodynamics of estuaries, these impacts will likely be manifested in higher trophic levels with possible impairments of the structure and function of these sensitive systems. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Growth and decline of shoreline industry in Sydney estuary (Australia) and influence on adjacent estuarine sediments.

    PubMed

    Birch, G F; Lean, J; Gunns, T

    2015-06-01

    Sydney estuary (Australia), like many urbanised waterways, is degraded due to an extended history of anthropogenic activity. Two major sources of contamination to this estuary are discharge by former shoreline industries and historic and contemporary catchment stormwater. The objectives of the present study were to document changes in shoreline land use from European settlement to the present day and determine the influence of this trend on the metal content of adjacent estuarine sediments. Temporal analysis of land use for seven time horizons between 1788 and 2010 showed rapid expansion of industry along much of the Sydney estuary foreshore soon after European settlement due to the benefits of easy and inexpensive access and readily available water for cooling and power. Shoreline industry attained maximum development in 1978 (32-km length) and declined rapidly to the present-day (9-km length) through redevelopment of industrial sites into medium- to high-density, high-value residential housing. Cores taken adjacent to 11 long-term industrial sites showed that past industrial practices contributed significantly to contamination of estuarine sediment. Subsurface metal concentrations were up to 35 times that of present-day surface sediment and over 100 times greater than natural background concentrations. Sedimentation rates for areas adjacent to shoreline industry were between 0.6 and 2.5 cm/year, and relaxation times were estimated at 50 to 100 years. Natural relaxation and non-disturbance of sediments may be the best management practice in most locations.

  6. Transport of Gas and Solutes in Permeable Estuarine Sediments

    DTIC Science & Technology

    2008-01-01

    subsurface methane accumulations that formed gas layers up to 2 cm thick at 3 to 10 cm sediment depth. This gas was collected in the chambers and the...reactive solutes in the surface layers of the bed. Gas producing organisms benefit from this filtration, i.e. methanogens from the filtration of organic

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

    PubMed

    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.

  8. Relationships Between Environmental Factors, Bacterial Indicators, and the Occurrence of Enteric Viruses in Estuarine Sediments

    PubMed Central

    LaBelle, Raymond L.; Gerba, Charles P.; Goyal, Sagar M.; Melnick, Joseph L.; Cech, Irina; Bogdan, Gregory F.

    1980-01-01

    Current standards for evaluation of the public health safety of recreational and shellfish-harvesting waters are based upon bacteriological analysis, but do not include an evaluation of the number of viruses. The objective of this study was to determine the occurrence of enteric viruses in estuarine sediments and to find a relationship, if any, between the presence of viruses in seawater or sediment or both and various biological and physicochemical characteristics of the environment. Viruses were found in greater numbers in sediment than in overlying seawater on a volume basis. Several types of enteroviruses were isolated: coxsackievirus types A16, B1, and B5, echovirus type 1, and poliovirus type 2. On several occasions, viruses were isolated from sediments when overlying seawaters met bacteriological water quality standards for recreational use. Statistical analysis of the relationship between viruses in seawater or in sediment and other variables measured yielded only one significant association: the number of viruses in sediment was found to be positively correlated with the number of fecal coliforms in sediment. No other physical, chemical, or biological characteristic of seawater or sediment that was measured showed statistically significant association with viral numbers. No correlation was found between bacterial indicators and virus in the overlying waters. The data indicated that evaluation of the presence of bacteria and viruses in sediment may provide additional insight into long-term water quality conditions and that indicator bacteria in water are not reflective of the concentration of enteric viruses in marine waters. PMID:6247974

  9. Sediment toxicity and benthic communities in mildly contaminated mudflats

    SciTech Connect

    Nipper, M.G.; Roper, D.S.; Williams, E.K.; Martin, M.L.; Van Dam, L.F.; Mills, G.N.

    1998-03-01

    Sediment physicochemical characteristics, benthic community structure, and toxicity were measured at reference and contaminated intertidal mudflats around the North Island of New Zealand. Chronic whole-sediment toxicity tests were conducted with the estuarine amphipod, Chaetocorophium lucasi and the marine bivalve, Macomona lilana, and pore-water toxicity tests were conducted with embryos of the echinoid, Fellaster zelandiae. Although concentrations of organic chemicals and heavy metals were up to several orders of magnitude higher at the sites considered to be contaminated, levels of contamination were relatively low compared to internationally based sediment quality guidelines. Although no pronounced difference was found in benthic community structure between reference and contaminated sites, multivariate analysis indicated that natural sediment characteristics and factors related to contamination may have been affecting community structure. Although benthic effects caused by present levels of contamination are not yet dramatic, subtle changes in community structure related to pollution may be occurring. The two whole-sediment and the pore-water toxicity tests presented different response patterns. Growth of C. lucasi and M. liliana was a less sensitive endpoint than survival. None of the three toxicity tests responded more strongly to the contaminated than to the reference sites, that is, neither natural-sediment and pore-water characteristics nor unmeasured contaminants affected the test organisms. It is possible that sediment collection and handling may have induced chemical changes, confounding interpretation of toxicity tests.

  10. Sensitivity of estuarine turbidity maximum to settling velocity, tidal mixing, and sediment supply

    USGS Publications Warehouse

    Warner, J.C.; Sherwood, C.R.; Geyer, W.R.; ,

    2007-01-01

    Estuarine turbidity maximum, numerical modeling, settling velocity, stratification The spatial and temporal distribution of suspended material in an Estuarine Turbidity Maxima (ETM) is primarily controlled by particle settling velocity, tidal mixing, shear-stress thresholds for resuspension, and sediment supply. We vary these parameters in numerical experiments of an idealized two-dimensional (x-z) estuary to demonstrate their affects on the development and retention of particles in an ETM. Parameters varied are the settling velocity (0.01, 0.1, and 0.5 mm/s), tidal amplitude (0.4 m 12 hour tide and 0.3 to 0.6 m 14 day spring neap cycle), and sediment availability (spatial supply limited or unlimited; and temporal supply as a riverine pulse during spring vs. neap tide). Results identify that particles with a low settling velocity are advected out of the estuary and particles with a high settling velocity provide little material transport to an ETM. Particles with an intermediate settling velocity develop an ETM with the greatest amount of material retained. For an unlimited supply of sediment the ETM and limit of salt intrusion co-vary during the spring neap cycle. The ETM migrates landward of the salt intrusion during spring tides and seaward during neap tides. For limited sediment supply the ETM does not respond as an erodible pool of sediment that advects landward and seaward with the salt front. The ETM is maintained seaward of the salt intrusion and controlled by the locus of sediment convergence in the bed. For temporal variability of sediment supplied from a riverine pulse, the ETM traps more sediment if the pulse encounters the salt intrusion at neap tides than during spring tides. ?? 2007 Elsevier B.V. All rights reserved.

  11. Transport of Gas and Solutes in Permeable Estuarine Sediments

    DTIC Science & Technology

    2012-09-30

    is demonstrated by measuring the spatial and temporal distribution of small bubbles produced by photosynthesis in sublittoral sands. − We...document contains color images. 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18. NUMBER OF...column Oxygen bubbles produced by photosynthesis in the sediment affect the concentrations of dissolved gases in the pore water. As soon these oxygen

  12. Transport of Gas and Solutes in Permeable Estuarine Sediments

    DTIC Science & Technology

    2011-09-30

    from the upper 10 cm and even deeper layers of shallow sands typically is photosynthetically active when exposed to light . For two dimensional plots of...ultrasonic and optical methods on sediment cores maintained at in-situ pressure, light and temperature and without changing the orientation of the...core. − Mapping of the spatial and temporal distribution of high sedimentary photosynthetic production and sites for free gas development

  13. Ecological periodic tables for nekton and benthic macrofaunal community usage of estuarine habitats Slides

    EPA Science Inventory

    Ecological periodic tables for nekton and benthic macrofaunal community usage of estuarine habitats Steven P. Ferraro, U.S. Environmental Protection Agency, Newport, OR Background/Questions/Methods The chemical periodic table, the Linnaean system of classification, and the Her...

  14. Ecological periodic tables for nekton and benthic macrofaunal community usage of estuarine habitats Slides

    EPA Science Inventory

    Ecological periodic tables for nekton and benthic macrofaunal community usage of estuarine habitats Steven P. Ferraro, U.S. Environmental Protection Agency, Newport, OR Background/Questions/Methods The chemical periodic table, the Linnaean system of classification, and the Her...

  15. Statistical comparison and correlation of zinc and lead in estuarine sediments along the western coast of Mauritius.

    PubMed

    Ramessur, Roshan T

    2004-10-01

    Cr, Zn and Pb were quantified using atomic absorption spectrometry (AAS) from urban and rural estuarine sediments collected along the western coast of Mauritius during the period July 2002-January 2003. The mean concentration of Cr (225.4 mg kg(-1)), Zn (107.0 mg kg(-1)) and Pb (27.0 mg kg(-1)) in sediments along the six estuaries can be considered below those from contaminated estuarine sediments. Zn and Pb were significantly higher in urban sediments downstream St. Louis River compared to a rural estuary at Tamarin at 5% significance level. Zn was also significantly lower in Tamarin compared to Petite Riviere Noire estuary. Cr was however not significantly different in sediments from the six estuaries and could be considered of basaltic origin and were correlated to neither lead nor zinc. The concentration of Zn and Pb were greatest in the more urbanised upper and lower reaches of the St. Louis estuary during the period of study and were also significantly positively correlated in the estuarine sediments indicating that the cycling of Pb and Zn were linked indicating a common source for Pb and Zn. The potential sources of Pb and Zn in the urban estuarine sediments were considered to arise from road runoff causing significant quantities to be trapped. At present, compared to contaminant levels found in the UK and elsewhere, Mauritius still looks relatively uncontaminated but there is growing concern about heavy metal contamination in urban estuaries. There is therefore a need for long-term studies in estuarine management to involve integrated strategies in which water-sediment interactions in estuaries need to be considered and international standards for sediment quality developed. Such studies undertaken in the future would further the understanding of the biogeochemical processes of estuarine systems in Mauritius which could then be used in environmental development schemes and effective coastal zone management.

  16. Intraspecific diet shift of Macoma balthica during community reassembly in an estuarine intertidal flat

    NASA Astrophysics Data System (ADS)

    Rossi, Francesca; Middelburg, Jack J.

    2011-05-01

    During community reassembly, consumers may express adaptive feeding behaviour in response to the presence of other species or according to their development. During the community reassembly after hypoxia of a temperate estuarine intertidal area, we quantified the microphytobenthos contribution to the diet of the three numerically dominant macrofauna consumers, using 13C-carbon tracing experiments. We then explored the relationships between their size and the microphytobenthos contribution to their diet. The polychaetes Hediste diversicolor and Pygospio elegans did not show a clear pattern of diet shift. Conversely, at a late stage of community reassembly, there was a dramatic decrease in the contribution of benthic microalgae to the diet of the clam Macoma balthica within the juvenile specimens (≤5 mm), which were recolonising the sediment. The contribution of microphytobenthos decreased with the size ( r = -0.81, n = 18) and the largest juveniles incorporated benthic microalgal carbon similarly to their co-specific adults found in the undisturbed areas. Including both juveniles and adults, the size-diet relationship of M. balthica followed an inverse logarithmic curve during community reassembly. Such shape differed from the linear relationship based on the natural abundance of stable carbon isotope as previously collected in the undisturbed surroundings. Our study provides evidence of diet shift during community reassembly and suggests that such diet shift might follow both consumer development in the recolonising areas and other processes related to successional stages.

  17. Differentiated availability of geochemical mercury pools controls methylmercury levels in estuarine sediment and biota.

    PubMed

    Jonsson, Sofi; Skyllberg, Ulf; Nilsson, Mats B; Lundberg, Erik; Andersson, Agneta; Björn, Erik

    2014-08-20

    Neurotoxic methylmercury (MeHg) formed from inorganic divalent mercury (Hg(II)) accumulates in aquatic biota and remains at high levels worldwide. It is poorly understood to what extent different geochemical Hg pools contribute to these levels. Here we report quantitative data on MeHg formation and bioaccumulation, in mesocosm water-sediment model ecosystems, using five Hg(II) and MeHg isotope tracers simulating recent Hg inputs to the water phase and Hg stored in sediment as bound to natural organic matter or as metacinnabar. Calculations for an estuarine ecosystem suggest that the chemical speciation of Hg(II) solid/adsorbed phases control the sediment Hg pool's contribution to MeHg, but that input of MeHg from terrestrial and atmospheric sources bioaccumulates to a substantially greater extent than MeHg formed in situ in sediment. Our findings emphasize the importance of MeHg loadings from catchment runoff to MeHg content in estuarine biota and we suggest that this contribution has been underestimated.

  18. Back-barrier and seabed sediment dynamics in the Albemarle-Pamlico estuarine system, North Carolina

    NASA Astrophysics Data System (ADS)

    Walsh, J. P.; Corbett, D. R.

    2016-02-01

    Estuaries are critical habitats as well as places where people live, recreate, and make their livelihood. Additionally, they are sites where land and sea interact, and sediments, and associated pollutants and carbon, are deposited, remobilized and accumulated. Many processes, such as river discharge, waves, tides, and sea-level rise, are operating in estuaries to cause sediment dynamics, impacting humans and organisms as a result. Recent research we have been engaged in across the Albemarle-Pamlico Estuarine System (APES) has investigated the sediments dynamics of this important estuary. The APES is the second largest estuary in the continental United States, consisting of the Albemarle and Pamlico sounds and the Pamlico River and Neuse River sub-estuaries. Although expansive in size, the system is shallow with minimal tidal range. Water and sediment discharge into the APES is modest, and the existence of few inlets along the Outer Banks limits mixing with the Atlantic Ocean. Human impact on the drainage basin and estuarine system is moderate and increasing over time. Over the last five years, a considerable volume of sedimentary process data has been collected over various timescales and locations in the APES. More specifically, work has included: deployments of instrumented tripods to examine seabed dynamics; collection and analysis of shallow cores and GIS investigation of aerial photographs and other data. This wealth of data highlights several insights: 1) shorelines are generally eroding ( 0.25 m/y and rapidly >3 m/y in places), but rates are temporally and spatially variable; 2) seabed resuspension is frequent, yet net accumulation of 2-4 mm/y is widespread in deeper locations; and 3) storms cause episodic, localized impacts (e.g., barrier breaches) on this large, shallow estuarine system.

  19. Modelling-based assessment of suspended sediment dynamics in a hypertidal estuarine channel

    NASA Astrophysics Data System (ADS)

    Amoudry, Laurent O.; Ramirez-Mendoza, Rafael; Souza, Alejandro J.; Brown, Jennifer M.

    2014-05-01

    We investigate the dynamics of suspended sediment transport in a hypertidal estuarine channel which displays a vertically sheared exchange flow. We apply a three-dimensional process-based model coupling hydrodynamics, turbulence and sediment transport to the Dee Estuary, in the north-west region of the UK. The numerical model is used to reproduce observations of suspended sediment and to assess physical processes responsible for the observed suspended sediment concentration patterns. The study period focuses on a calm period during which wave-current interactions can reasonably be neglected. Good agreement between model and observations has been obtained. A series of numerical experiments aim to isolate specific processes and confirm that the suspended sediment dynamics result primarily from advection of a longitudinal gradient in concentration during our study period, combined with resuspension and vertical exchange processes. Horizontal advection of sediment presents a strong semi-diurnal variability, while vertical exchange processes (including time-varying settling as a proxy for flocculation) exhibit a quarter-diurnal variability. Sediment input from the river is found to have very little importance, and spatial gradients in suspended concentration are generated by spatial heterogeneity in bed sediment characteristics and spatial variations in turbulence and bed shear stress.

  20. Associations between dioxins/furans and dioxin-like PCBs in estuarine sediment and blue crab

    USGS Publications Warehouse

    Liebens, J.; Mohrherr, C.J.; Karouna-Renier, N. K.; Snyder, R.A.; Rao, K.R.

    2011-01-01

    The objective of the present study was to evaluate the relationships between the quantity, toxicity, and compositional profile of dioxin/furan compounds (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in estuarine sediment and in the blue crab (Callinectes sapidus). Sediment and blue crab samples were collected in three small urban estuaries that are in relatively close proximity to each other. Results show that differences between PCDD/F and DL-PCB mass concentrations and total toxic equivalents (TEQ) toxicity in sediments of the three estuaries are reflected in those of the blue crab. TEQs are higher in the hepatopancreas of the crabs than in the sediment, but the concentration factor is inversely proportional to the TEQ in the sediments. Congener profiles in the crabs are systematically different from those in the sediments, and the difference is more pronounced for PCDD/Fs than for DL-PCBs, possibly due to differences in metabolization rates. Compared with sediment profiles, more lesser-chlorinated PCDD/Fs that have higher TEFs accumulate in crab hepatopancreas. This selective bioaccumulation of PCDD/Fs results in a TEQ augmentation in crab hepatopancreas compared with sediments. The bioaccumulation in the blue crab is also selective for PCDD/Fs over DL-PCBs. ?? 2011 Springer Science+Business Media B.V.

  1. Assessing sublethal levels of sediment contamination using the estuarine amphipod Leptocheirus plumulosus

    SciTech Connect

    McGee, B.L.; Schlekat, C.E.; Reinharz, E. )

    1993-03-01

    Recent emphasis on the incorporation of sublethal end points into sediment toxicity test methods follows the realization that acute lethality tests may not provide sufficient sensitivity for predicting subtle ecological effects of sediment contamination. To this end, a partial life-cycle test with the amphipod Leptocheirus plumulosus Shoemaker was evaluated for solid-phase testing of contaminated estuarine sediments. Initially, juvenile and adult Leptocheirus plumulosus and the amphipod Hyalella azteca were exposed to gradients of chemical contamination prepared by diluting field-collected contaminated sediment with texturally similar reference sediment. Ten-day exposure results indicate juvenile Leptocheirus plumulosus is more sensitive than adult Leptocheirus plumulosus and Hyalella azteca, with significant mortality of juvenile Leptocheirus plumulosus occurring in sediment diluted to 12.5% of the adult lowest-observed-effect concentration (LOEC). Long-term exposure of juveniles to dilutions of the acute juvenile LOEC shows significant effects on growth in sediment concentrations below the lethal threshold. Effect of reproductive end points parallel growth effects. Evaluation of nontoxicant experimental variables indicates significant effects of temperature and feeding regime on sensitivity of juvenile Leptocheirus plumulosus to contaminated sediment. Trace element concentrations were determined for the following: As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn.

  2. Accumulation and trace-metal variability of estuarine sediments, Barataria Basin, Louisiana

    SciTech Connect

    Landrum, K.

    1994-09-01

    Prior to government regulation, little monitoring of metal discharges into the canals, bayous, and rivers that drain estuarine systems occurred. Discharges of heavy metals are now limited through the use of regulatory permit programs for industries and municipalities. Resource management of economically important estuarine systems has fostered increasing concern over the accumulation of heavy metal pollutants in water, sediments, and biota of these dynamic areas. As a result of the low solubility of most metals, very small amounts are transported in solution. Most metals transported by rivers are tightly bound in the aluminosilicate phases associated with the suspended and bottom sediments. The bottom sediments of lakes and estuaries have served as sinks for the accumulation of heavy metals from natural weathering products, spills, effluents, runoff, and atmospheric sources. These accumulations have left a metal signature upon essentially every bay and estuary in the northern Gulf. The acid-leachable concentrations of 14 metals (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn) were determined for 136 bottom sediment samples and 40 core interval samples by plasma emission analysis. Elevated concentrations in heavy metals near the centers of the Barataria basin lakes reflect the strong correlations between increased trace-metal concentrations and smaller grain-size sediments. Heavy metal concentrations within the 2-cm core intervals indicate increases in Ba, Cr, Cd, Pb, and Zn (10-30%) within Barataria basin sediments accumulated in the last 75 yr. Although anthropogenic heavy metal contributions within Barataria basin exist, comparisons of average trace-metal concentrations from the study areas with those of other Gulf Coast estuaries and with the average shale indicate that the heavy metal contents of upper Barataria basin sediments have not reached alarming levels.

  3. Geochemical Screening of Contaminated Marine and Estuarine Sediments

    NASA Astrophysics Data System (ADS)

    Kruge, M. A.

    2004-05-01

    Waterways near urban centers have been subject to pollution by human activities for centuries. This process greatly intensified with the advent of the Industrial Revolution and the attendant exponential population increase in coastal areas. The co-occurrence of port facilities for ocean-going vessels, large factories, major power generating stations, dense automotive transportation networks, and massive wastewater outfalls, all in compact geographical areas, has produced severe environmental stress. In recent decades, the growing awareness of the seriousness of coastal urban environmental degradation has inspired intensive efforts at pollution prevention and remediation. To better understand pollution dynamics over time in an aquatic urban setting, a program of intensive sampling and analysis leading to the creation of geographic information systems (GIS) would be desirable. Chemical evaluation of sediments for pollution remains a costly and time-consuming procedure, particularly for organic analysis. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) offers a practical alternative for rapid, inexpensive molecular organic analysis, simply employing milligram quantities of dry, whole sediment. The compounds detected comprise an information-rich mixture of thermally extractable components and the products of the thermal decomposition of (bio)polymers present in the sample. These include PAHs, petroleum-derived hopanes, organonitrogen compounds, and linear alkylbenzenes, as illustrated with examples from Long Island Sound and the Passaic River (USA) and Barcelona harbor (Spain).

  4. Impact of estuarine gradients on reductive dechlorination of 1,2,3,4-tetrachlorodibenzo-p-dioxin in river sediment enrichment cultures.

    PubMed

    Dam, Hang T; Häggblom, Max M

    2017-02-01

    Polychlorinated dibenzo-p-dioxins (PCDDs) are among the most persistent organic pollutants. Although the total input of PCDDs into the environment has decreased substantially over the past four decades, their input via non-point sources is still increasing, especially in estuarine metropolitan areas. Here we report on the microbially mediated reductive dechlorination of PCDDs in anaerobic enrichment cultures established from sediments collected from five locations along the Hackensack River, NJ and investigate the impacts of sediment physicochemical characteristics on dechlorination activity. Dechlorination of 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-TeCDD) and abundance of Dehalococcoides spp. negatively correlated with salinity and sulfate concentration in sediments used to establish the cultures. 1,2,3,4-TeCDD was dechlorinated to a lesser extent in cultures established from sediments from the tidally influenced estuarine mouth of the river. In cultures established from low salinity sediments, 1,2,3,4-TeCDD was reductively dechlorinated with the accumulation of 2-monochlorodibenzo-p-dioxin as the major product. Sulfate concentrations above 2 mM inhibited 1,2,3,4-TecDD dechlorination activity. Consecutive lateral- and peri- dechlorination took place in enrichment cultures with a minimal accumulation of 2,3-dichlorodibenzo-p-dioxin in active cultures. A Dehalococcoides spp. community was enriched and accounted for up to 64% of Chloroflexi detected in these sediment cultures.

  5. Mediated distribution pattern of organic compounds in estuarine sediment by anthropogenic debris.

    PubMed

    Wu, Chen-Chou; Bao, Lian-Jun; Tao, Shu; Zeng, Eddy Y

    2016-09-15

    Natural organic matter and grain size are considered as important parameters dictating the transport and fate of organic compounds in sediment. However, increasing evidence suggested that manufactured debris may alter the underlying mechanisms for biogeochemical cycling of organic compounds. To examine this assumption, estuarine sediment and embedded debris were collected from a fishery base in Guangdong Province of South China and analyzed for organophosphorus flame retardants (OPFRs), phthalates (PAEs), organotin compounds (OTs) and dichlorodiphenyltrichloroethanes (DDTs). Coarse-size debris (>200μm) were heterogeneously distributed in sediment, and most abundant near the boat maintenance facilities, aquaculture zone and shipping channel. The median concentrations of OPFRs, OTs, PAEs and DDTs in debris were 11, 0.2, 11 and 3.9μgg(-1) dry sample weight(-1), respectively, 1 to 3 orders of magnitude greater than those in bulk sediment (19, 60, 240 and 570ngg(-1) dry sample weight(-1), respectively). Furthermore, OPFRs, OTs and PAEs were mostly (>99%) enriched in coarse-size (63-2000μm) sediment, and there was no significant correlation (p>0.05) between the concentrations of OPFRs, OTs and PAEs in bulk and size-fractioned sediment samples and total organic carbon or grain size, similar to the distribution pattern of DDTs reported previously. When distinct debris were removed from the light-density (<1.7gcm(-3)) fraction of coarse-size (200-2000μm) sediment, the concentration levels of OPFRs, OTs, PAEs and DDTs declined by 84%, 59%, 55% and 7%, respectively. Obviously, debris irregularly distributed in sediment can alter the sediment sorption capacity for OPFRs, OTs and PAEs, and thus may undermine the significance of organic matter and grain size to the distribution of organic chemicals in sediment. Finally, commonly used procedures for preparing sediment samples and screening of debris may disturb the grain size distribution or underestimate the abundance of

  6. Calibration of an estuarine sediment transport model to sediment fluxes as an intermediate step for simulation of geomorphic evolution

    USGS Publications Warehouse

    Ganju, N.K.; Schoellhamer, D.H.

    2009-01-01

    Modeling geomorphic evolution in estuaries is necessary to model the fate of legacy contaminants in the bed sediment and the effect of climate change, watershed alterations, sea level rise, construction projects, and restoration efforts. Coupled hydrodynamic and sediment transport models used for this purpose typically are calibrated to water level, currents, and/or suspended-sediment concentrations. However, small errors in these tidal-timescale models can accumulate to cause major errors in geomorphic evolution, which may not be obvious. Here we present an intermediate step towards simulating decadal-timescale geomorphic change: calibration to estimated sediment fluxes (mass/time) at two cross-sections within an estuary. Accurate representation of sediment fluxes gives confidence in representation of sediment supply to and from the estuary during those periods. Several years of sediment flux data are available for the landward and seaward boundaries of Suisun Bay, California, the landward-most embayment of San Francisco Bay. Sediment flux observations suggest that episodic freshwater flows export sediment from Suisun Bay, while gravitational circulation during the dry season imports sediment from seaward sources. The Regional Oceanic Modeling System (ROMS), a three-dimensional coupled hydrodynamic/sediment transport model, was adapted for Suisun Bay, for the purposes of hindcasting 19th and 20th century bathymetric change, and simulating geomorphic response to sea level rise and climatic variability in the 21st century. The sediment transport parameters were calibrated using the sediment flux data from 1997 (a relatively wet year) and 2004 (a relatively dry year). The remaining years of data (1998, 2002, 2003) were used for validation. The model represents the inter-annual and annual sediment flux variability, while net sediment import/export is accurately modeled for three of the five years. The use of sediment flux data for calibrating an estuarine geomorphic

  7. Populations of Methane-Producing Bacteria and In Vitro Methanogenesis in Salt Marsh and Estuarine Sediments

    PubMed Central

    Jones, William J.; Paynter, Malcolm J. B.

    1980-01-01

    Most probable numbers (MPNs) of methanogens in various salt marsh and estuarine sediments were determined with an anaerobic, habitat-simulating culture medium with 80% H2 plus 20% CO2 as substrate. Average MPNs for the short Spartina (SS) marsh sediments of Sapelo Island, Ga., were maximal at the 5- to 7-cm depth (1.2 × 107/g of dry sediment). Populations decreased to approximately 880/g of dry sediment at the 34- to 36-cm depth. There was no significant difference between summer and winter populations. In tall Spartina (TS) marsh sediments, average populations were maximal (1.2 × 106/g of dry sediment) in the upper 0- to 2-cm zone; populations from the 5- to 36-cm zones were similar (average of 9 × 104/g of dry sediment). Methanogenic populations for TS sediments of James Island Creek marsh, Charleston, S.C., were similar (average of 3 × 106/g of dry sediment) for all depths tested (0 to 22 cm), which was comparable to the trend observed for TS sediments at Sapelo Island, Ga. Sediment grab samples collected along a transect of James Island Creek and its adjacent Spartina marsh had MPNs that were approximately 20 times greater for the region of Spartina growth (average of 106/g of dry sediment) compared with the channel (approximately 5 × 104 methanogens per g of dry sediment). A similar trend was found at Pawley's Island marsh, S.C., but populations were approximately one order of magnitude lower. In vitro rates of methanogenesis with SS sediments incubated under 80% H2-20% CO2 showed that the 5- to 7-cm region exhibited maximal activity (51 nmol of CH4 g−1 h−1), which was greater than rates for sediments above and below this depth. SS sediment samples (5 to 7 cm) incubated under 100% N2 and supplemented with formate exhibited rates of methanogenesis similar to those generated by samples under 80% H2-20% CO2. Replacing the N2 atmosphere with H2 resulted in an eightfold decrease in the rate of methanogenesis. In vitro methanogenic activity by TS salt marsh

  8. A vacuum-operated pore-water extractor for estuarine and freshwater sediments

    USGS Publications Warehouse

    Winger, Parley V.; Lasier, Peter J.

    1991-01-01

    A vacuum-operated pore-water extractor for estuarine and freshwater sediments was developed and constructed from a fused-glass air stone attached with aquarium airline tubing to a 30 or 60 cc polypropylene syringe. Pore water is extracted by inserting the air stone into the sediment and creating a vacuum by retracting and bracing the syringe plunger. A hand-operated vacuum pump attached to a filtration flask was also evaluated as an alternative vacuum source. The volume and time to extract pore water varies with the number of devices and the sediment particle size. Extraction time is longer for fine sediments than for sandy sediments. Four liters of sediment generally yield between 500 and 1,500 mL of pore water. The sediment that surrounds and accumulates on the air stone acts as a filter, and, except for the first few milliliters, the collected pore water is clear. Because there is no exposure to air or avenue for escape, volatile compounds andin situ characteristics are retained in the extracted pore water.

  9. Bulk sediment 14C dating in an estuarine environment: How accurate can it be?

    NASA Astrophysics Data System (ADS)

    Lougheed, Bryan C.; Obrochta, Stephen P.; Lenz, Conny; Mellström, Anette; Metcalfe, Brett; Muscheler, Raimund; Reinholdsson, Maja; Snowball, Ian; Zillén, Lovisa

    2017-02-01

    Due to a lack of marine macrofossils in many sediment cores from the estuarine Baltic Sea, researchers are often forced to carry out 14C determinations on bulk sediment samples. However, ambiguity surrounding the carbon source pathways that contribute to bulk sediment formation introduces a large uncertainty into 14C geochronologies based on such samples, and such uncertainty may not have been fully considered in previous Baltic Sea studies. We quantify this uncertainty by analyzing bulk sediment 14C determinations carried out on densely spaced intervals in independently dated late-Holocene sediment sequences from two central Baltic Sea cores. Our results show a difference of 600 14C yr in median bulk sediment reservoir age, or R(t)bulk, between the two core locations ( 1200 14C yr for one core, 620 14C yr for the other), indicating large spatial variation. Furthermore, we also find large downcore (i.e., temporal) R(t)bulk variation of at least 200 14C yr for both cores. We also find a difference of 585 14C yr between two samples taken from the same core depth. We propose that studies using bulk sediment 14C dating in large brackish water bodies should take such spatiotemporal variation in R(t)bulk into account when assessing uncertainties, thus leading to a larger, but more accurate, calibrated age range.

  10. Mercury Stable Isotopic Composition of Monomethylmercury in Estuarine Sediments and Pure Cultures of Mercury Methylating Bacteria

    NASA Astrophysics Data System (ADS)

    Janssen, S.; Johnson, M. W.; Barkay, T.; Blum, J. D.; Reinfelder, J. R.

    2014-12-01

    Tracking monomethylmercury (MeHg) from its source in soils and sediments through various environmental compartments and transformations is critical to understanding its accumulation in aquatic and terrestrial food webs. Advances in the field of mercury (Hg) stable isotopes have allowed for the tracking of discrete Hg sources and the examination of photochemical and bacterial transformations. Despite analytical advances, measuring the Hg stable isotopic signature of MeHg in environmental samples or laboratory experiments remains challenging due to difficulties in the quantitative separation of MeHg from complex matrices with high concentrations of inorganic Hg. To address these challenges, we have developed a MeHg isolation method for sediments and bacterial cultures which involves separation by gas chromatography. The MeHg eluting from the GC is passed through a pyrolysis column and purged onto a gold amalgam trap which is then desorbed into a final oxidizing solution. A MeHg reference standard carried through our separation process retained its isotopic composition within 0.02 ‰ for δ202Hg, and for native estuarine sediments, MeHg recoveries were 80% to 100%. For sediment samples from the Hackensack and Passaic Rivers (New Jersey, USA), δ202Hg values for MeHg varied from -1.2 to +0.58 ‰ (relative to SRM 3133) and for individual samples were significantly different from that of total Hg (-0.38 ± 0.06 ‰). No mass independent fractionation was observed in MeHg or total Hg from these sediments. Pure cultures of Geobacter sulfurreducens, grown under fermentative conditions showed preferential enrichment of lighter isotopes (lower δ202Hg) during Hg methylation. The Hg stable isotope signatures of MeHg in sediments and laboratory methylation experiments will be discussed in the context of the formation and degradation of MeHg in the environment and the bioaccumulation of MeHg in estuarine food webs.

  11. Evaluation of ADCP backscatter inversion to suspended sediment concentration in estuarine environments

    NASA Astrophysics Data System (ADS)

    Park, Hyo-Bong; Lee, Guan-hong

    2016-03-01

    Acoustic Doppler Current Profilers (ADCP), designed for measuring velocity profiles, are widely used for the estimation of suspended sediment concentration from acoustic backscatter strength, but its application to estuarine environments requires further refinement. In this study, we examined the inversion capability of two ADCPs with 600 and 1200 kHz in three Korean estuaries: the supra-macrotidal Han River Estuary (HRE), microtidal Nakdong River Estuary (NRE), and anthropogenically altered macrotidal Yeongsan River Estuary (YRE). In particular, we examined the relative importance of the sound attenuations due to water (αw) and sediment (αs) in response to sediment characteristics (size and concentration) as well as changing salinity and temperature. The inverted concentration was compared with reference concentrations obtained either from water samples or Optical Backscatter Sensors. In NRE and YRE, where suspended sediment concentrations were less than 0.2 g/l, the acoustic inversion performed poorly only with αs (r = 0.20 and 0.38 for NRE and YRE, respectively), but well with αw (r = 0.66 and 0.42 for NRE and YRE, respectively). Thus, it is important to accurately constrain αw in low-concentration estuarine environments. However, we did not find that the varying αw performed considerably better than the constant αw. On the other hand, the acoustic inversion was poorest at HRE regardless of αw and αs (r = 0.71 and mean relative error = 45%). The large discrepancy appears to result from the poorly constrained, spatially and temporally varying sediment characteristics (grain size, density and concentration) due to non-local sediment transport in the macrotidal HRE.

  12. Sediment composition influences spatial variation in the abundance of human pathogen indicator bacteria within an estuarine environment.

    PubMed

    Perkins, Tracy L; Clements, Katie; Baas, Jaco H; Jago, Colin F; Jones, Davey L; Malham, Shelagh K; McDonald, James E

    2014-01-01

    Faecal contamination of estuarine and coastal waters can pose a risk to human health, particularly in areas used for shellfish production or recreation. Routine microbiological water quality testing highlights areas of faecal indicator bacteria (FIB) contamination within the water column, but fails to consider the abundance of FIB in sediments, which under certain hydrodynamic conditions can become resuspended. Sediments can enhance the survival of FIB in estuarine environments, but the influence of sediment composition on the ecology and abundance of FIB is poorly understood. To determine the relationship between sediment composition (grain size and organic matter) and the abundance of pathogen indicator bacteria (PIB), sediments were collected from four transverse transects of the Conwy estuary, UK. The abundance of culturable Escherichia coli, total coliforms, enterococci, Campylobacter, Salmonella and Vibrio spp. in sediments was determined in relation to sediment grain size, organic matter content, salinity, depth and temperature. Sediments that contained higher proportions of silt and/or clay and associated organic matter content showed significant positive correlations with the abundance of PIB. Furthermore, the abundance of each bacterial group was positively correlated with the presence of all other groups enumerated. Campylobacter spp. were not isolated from estuarine sediments. Comparisons of the number of culturable E. coli, total coliforms and Vibrio spp. in sediments and the water column revealed that their abundance was 281, 433 and 58-fold greater in sediments (colony forming units (CFU)/100g) when compared with the water column (CFU/100ml), respectively. These data provide important insights into sediment compositions that promote the abundance of PIB in estuarine environments, with important implications for the modelling and prediction of public health risk based on sediment resuspension and transport.

  13. Anthropogenic Influences on Estuarine Sedimentation in Salem Sound, MA

    NASA Astrophysics Data System (ADS)

    Kristiansen, E. R.; Hubeny, J. B.; Zhu, J.; Olsen, C. R.; Warren, B.

    2010-12-01

    The Salem Sound watershed (MA) historically has been a region of significant industrial activity. Two specific point sources for pollution in the region are the South Essex Sewerage District (SESD) wastewater treatment facility, and the Salem Harbor Power Station, a coal-burning power plant. This study tests the hypothesis that human impact on Salem Sound is preserved in the sediment record. A sediment core was taken near the location of the SESD outfall. This core was analyzed for content of organic matter via loss on ignition (LOI), as well as magnetic susceptibility. An age model was constructed using 137Cs and 210Pb. Below 31 cm (mid-nineteenth century), the core contains mean background values of 2.7% LOI and values increase above this depth. At 21cm, a rapid increase in organic matter concentration from 6.6% to 11.8% is observed. This depth corresponds to ~1905 which is contemporaneous with construction of the outfall pipe discharging raw wastewater. At a depth of 7 cm (mid 1970s), LOI values decrease from 11.7% to 9.3%. This shift is likely attributed to SESD beginning primary treatment in 1977. LOI values continue to drop at 2cm (late 1990s), from 7.8% to 6.3%, and remain at 6.1% to the modern surface, likely a result of SESD upgrading to secondary treatment in 1998. Magnetic susceptibility also shows variability down core that is likely attributed to human impact. At a depth of approximately 20cm susceptibility values start increasing from 4.2 SI units until they reach a peak at 15cm (8.8 SI units). This increase can be attributed to the industrial revolution and increased industrial activity in the area. A decrease in susceptibility is observed at 15cm to 11cm (5.6 SI units) that may be attributed to the Great Depression and less fossil fuels being burned due to the economic situation. At approximately 10cm and 8.0 SI units, an increasing trend is first observed. This trend continues up to the modern surface where it eventually reaches 19.9 SI units. This

  14. Effects of sevin on development of experimental estuarine communities.

    PubMed

    Tagatz, M E; Ivey, J M; Lehman, H K; Oglesby, J L

    1979-07-01

    The composition of animal communities developing from planktonic larvae in aquariums. A marked increase in the abundance of the annelid Polydora ligni in aquariums containing sand and flowing estuarine water was altered in the presence of the carbamate insecticide Sevin (carbaryl). Treatments were control and concentrations of Sevin that averaged 1.1, 11.1, and 103 micrograms/l; each treatment was replicated 8 times. Animals that colonized aquarium sand were collected in a 1-mm mesh sieve after 10 wk of exposure. Mollusks' arthropods, annelids, and nemerteans were the numerically dominant phyla. The average number of species per aquarium was significantly less (alpha = 0.05) in aquariums containing 11.1 or 103 micrograms/l than in those containing 1.1 micrograms/l or in control aquariums. The abundant clam Ensis minor grew significantly less in length at the higher concentrations of Sevin. The amphipod Corophium acherusicum was particularly affected; significantly fewer were found at all concentrations than in the control aquariums containing 103 micrograms/l corresponded to a marked decrease in the number of other annelids and to a significant absence of nemerteans.

  15. Maps showing textural characteristics of benthic sediments in the Corpus Christi Bay estuarine system, south Texas

    USGS Publications Warehouse

    Shideler, Gerald L.; Stelting, Charles E.; McGowen, Joseph H.

    1981-01-01

    Corpus Christi Bay is a heavily used estuary on the south Texas coast in the northwest Gulf of Mexico (fig. 1).  The Bay is stressed by diverse activities which could substantially affect its ecosystem.  Such activities include shipping, resource production (oil, gas, and construction aggregate), commercial and sport fishing, and recreation.  Shipping activities alone have had a substantial impact on the bay.  For example, the past maintenance of navigation channels has required extensive dredging and spoil disposal within the estuarine system.  Numerous subaqueous spoil disposal sites and subaerial spoil banks are present throughout the bay (fig. 1), and the selection of future spoil disposal sites is becoming a critical local problem.  As activities in the bay increase, the need for effective environmental management becomes increasingly important, and effective management necessitates a good understanding of the bay's physical characteristics.  The objective of this study is to provide detailed information about the textural composition of bottom sediments within the estuarine system, information which could be used in making environmental-management decisions.  Visual descriptions of bottom sediments in Corpus Christi Bay and adjacent areas have been presented by McGowen and Morton (1979).  Additionally, a study of the textures of sediments on the Inner Continental Shelf adjacent to the bay has been presented by Shideler and Berryhill (1977).

  16. Natural and anthropogenic heavy metals in estuarine cohesive sediments: geochemistry and bioavailability

    NASA Astrophysics Data System (ADS)

    Grecco, Laura Edith; Gómez, Eduardo Alberto; Botté, Sandra Elizabeth; Marcos, Ángel Omar; Marcovecchio, Jorge Eduardo; Cuadrado, Diana Graciela

    2011-03-01

    The geochemistry, mineralogy, and grain size distribution of several estuarine cohesive sediment samples from potentially human-influenced areas without such an influence were analyzed to determine the natural heavy metal content and evaluate its impact on the Bahía Blanca estuarine environment. The data were compared with different ranges of concentrations for heavy metals in marine sediments established by the NOAA Screening Quick Reference Tables in which values range from background levels to those considered toxic to the marine environment. Our total heavy metal contents were below the established hazardous levels in all the analyzed samples, even though the potentially human-influenced areas (harbors, industry, urban spread) showed the highest total concentration values as well as greater percentages of bioavailable compounds. This would imply a low and not extensive anthropogenic input into the environment. The relatively high proportions in which Cd, Pb, and Cr appear as bioavailable compounds at some sites not influenced by human activity suggest the presence of a natural source for these elements. This could be attributed to the weathering of naturally occurring volcanic minerals, indicating that special care must be taken when monitoring of sediment for anthropogenic activity is carried out within this environment. According to the results obtained, and in order to minimize the environmental impact caused by periodic water injection dredging, relocation of sewage outfalls from vessel mooring areas into open waters is strongly recommended.

  17. Sedimentation: Potential Biological Effects of Dredging Operations in Estuarine and Marine Environments

    DTIC Science & Technology

    2005-05-01

    higher concentrations may dilute planktonic food resources and suppress food ingestion. Corals and Tropical Coral Reefs . Heavy sedimentation on corals ...recruitment, decreased calcification, decreased net productivity and slower rates of reef accretion (Rogers 1990). The distribution of some coral ...communities has been related to suspended sediment load (West and van Woesik 2001). Adverse impacts to corals and coral reef organisms from sedimentation may

  18. Long-Term Survival of Fecal Indicator Bacteria in Estuarine Sediment

    NASA Astrophysics Data System (ADS)

    Ferguson, A. S.; Layton, A.; Culligan, P. J.; Kenna, T. C.; Mailloux, B. J.

    2010-12-01

    Fecal contamination of marine and freshwater environments can negatively impact water quality, leading to contaminated drinking water as well as the closure of recreational beaches and waterways. Fecal contamination is routinely assessed using fecal indicator bacteria (FIB), and even though the potential for their long-term survival or proliferation in sediments exist, information linking deposition of FIB with sediment age is scarce. We evaluate sediments as a reservoir for culturable FIB, by examining dated sediments from the lower Hudson River estuary for Escherichia coli (E. coli), enterococcus, and Bacteroides. Sediment cores were collected from in the vicinity of the George Washington (GWB) and Tappan Zee (TZB) Bridges NY. Sediment deposition ages were constrained using gamma emitting radionuclides and pollution chronology. Culturable E. coli and enterococcus were quantified using a culture-based most probable number method (ColilertTM, Idexx Laboratories). Molecular based methods were used to quantify E. coli and Bacteroides. In the GWB core, viable enterococcus or E. coli were consistently detected in sediment younger than the 1960s with maximum concentrations of 39 and 171 cells/g, respectively. In the TZB core, only enterococcus was sporadically detected in sediment younger than 1950 with a maximum concentration of 79 cells/g. Molecular Bacteroides and E. coli were detected in all core samples with a geometric mean of 4.2x104 and 1.2x105 copies/g, respectively. Results indicate that fecal bacteria can survive within estuarine sediments for decades, suggesting that sediments could be a significant and persistent source of bacterial pollution.

  19. Estuarine circulation versus tidal pumping: Sediment transport in a well-mixed tidal inlet

    NASA Astrophysics Data System (ADS)

    Becherer, Johannes; Flöser, Götz; Umlauf, Lars; Burchard, Hans

    2016-08-01

    High-resolution water column observations have been carried out in the Wadden Sea to understand suspended particulate matter (SPM) transport in well-mixed tidal channels. These observations include more than 4000 consecutive CTD, microstructure shear and turbidity profiles from a free-falling microstructure probe, as well as velocity data from an ADCP and SPM samples for calibration. A horizontal density gradient was established by a landward temperature gradient built up during an extraordinarily warm and calm spring season. Tidal averaging along σ-layers (relative depth) provides the first direct observations of along-channel estuarine circulation in the Wadden Sea, with net inflow near the bottom and outflow near the surface. Increased westerly (up-estuary) winds during the second part of the campaign weakened and eventually even reversed estuarine circulation and yielded a net barotropic eastward transport. SPM concentrations showed a strong quarter-diurnal signal with maxima near full flood and full ebb and were generally lower during the calm period and increased during the windy period, mainly due to wave-related resuspension over nearby intertidal flats. The sediment flux analysis was based on a decomposition of the vertically integrated SPM flux into a barotropic advective component, an estuarine circulation component and a tidal pumping component. As a result, tidal pumping (due to ebb-dominance weakly seaward) dominated the SPM flux during calm conditions, whereas barotropic advection dominated the strong landward SPM flux during the windy period. Along-channel estuarine circulation is found to be of minor importance for the net SPM transport in such well-mixed systems.

  20. Sorption of cadmium to bacterial extracellular polymeric sediment coatings under estuarine conditions

    SciTech Connect

    Schlekat, C.E.; Decho, A.W.; Chandler, G.T.

    1998-09-01

    Microbial extracellular polymeric substances (EPS) are ubiquitous features in aquatic environments. Produced by surface-adherent bacteria and microalgae, EPS are often present as coatings on surfaces of sediment particles and exhibit high affinities for divalent cationic metals. Thus, EPS sediment coatings may participate in the fate of potentially toxic metals. The authors coated particulate silica with EPS produced by NISC1, a bacterium isolated from estuarine sediments, in order to measure the metal binding characteristics of these coatings. They used the radioisotope {sup 109}Cd to measure effects of salinity, Cd concentration, and pH on Cd sorption to EPS-coated (EPS-silica) silica and to noncoated silica (NC-silica). Also, Cd sorption by NISC1 EPS coatings was compared to coatings of polymers formed by the bacterium, Alteromonas atlantica and the alga, Macrocystis porifera. Under all circumstances, EPS coatings increased the affinity of silica for Cd. Extracellular polymeric substance-particulate aggregates rapidly sorbed up to 90% of Cd from aqueous solution. Extracellular polymeric substance sediment coatings exhibited a maximum log distribution coefficient (K{sub d}) of 6.5 at 2.5%. Sorption of Cd to NC-silica was affected by salinity and metal concentration, whereas sorption of Cd to EPS-silica was only affected by salinity under high metal concentrations. Changes in pH had a dramatic effect on Cd sorption, with the proportion of free Cd to sorbed Cd changing from approximately 90% at pH 5 to 5% at pH 9. Desorption of Cd from EPS-silica was enhanced with increasing salinity. These experiments suggest that EPS coatings actively participate in binding dissolved overlying and pore-water metals in estuarine sediments.

  1. Accumulation and toxicity of metal oxide nanoparticles in a soft-sediment estuarine amphipod.

    PubMed

    Hanna, Shannon K; Miller, Robert J; Zhou, Dongxu; Keller, Arturo A; Lenihan, Hunter S

    2013-10-15

    Estuarine and marine sediments are a probable end point for many engineered nanoparticles (ENPs) due to enhanced aggregation and sedimentation in marine waters, as well as uptake and deposition by suspension-feeding organisms on the seafloor. Benthic infaunal organisms living in sediments encounter relatively high concentrations of pollutants and may also suffer toxic effects of ENPs. We tested whether three heavily used metal oxide ENPs, zinc oxide (ZnO), copper oxide (CuO), and nickel oxide (NiO) were toxic to an estuarine amphipod, Leptocheirus plumulosus. We used results from 10-day laboratory bioassays to estimate potential demographic impacts of ENP exposure. We also evaluated fate and transport pathways of the ENPs in the experiments to elucidate routes of uptake and exposure. Dissolved Zn was found in sediment pore water and overlying water samples at 10 fold the concentrations of Cu or Ni, a pattern indicative of the relatively high dissolution rate of ZnO ENPs compared with CuO and NiO ENPs. Accumulation of metals in amphipod tissues increased with exposure concentrations for all three ENPs, suggesting possible exposure pathways to higher taxa. Amphipods accumulated ≤600 μg Zn and Cu g(-1) and 1000 μg Ni g(-1). Amphipod mortality increased with ZnO and CuO concentrations, but showed no significant increase with NiO to concentrations as high as 2000 μg g(-1). The median lethal concentration in sediment (LC50) of ZnO was 763 μg g(-1) and 868 μg g(-1) for CuO ENPs. Our results indicate that ZnO and CuO ENPs, but not NiO ENPs, are toxic to L. plumulosus and that ZnO toxicity primarily results from Zn ion exposure while CuO toxicity is due to nanoparticle exposure.

  2. The capability of estuarine sediments to remove nitrogen: implications for drinking water resource in Yangtze Estuary.

    PubMed

    Liu, Lin; Wang, Dongqi; Deng, Huanguang; Li, Yangjie; Chang, Siqi; Wu, Zhanlei; Yu, Lin; Hu, Yujie; Yu, Zhongjie; Chen, Zhenlou

    2014-09-01

    Water in the Yangtze Estuary is fresh most of the year because of the large discharge of Yangtze River. The Qingcaosha Reservoir built on the Changxing Island in the Yangtze Estuary is an estuarine reservoir for drinking water. Denitrification rate in the top 10 cm sediment of the intertidal marshes and bare mudflat of Yangtze Estuarine islands was measured by the acetylene inhibition method. Annual denitrification rate in the top 10 cm of sediment was 23.1 μmol m(-2) h(-1) in marshes (ranged from 7.5 to 42.1 μmol m(-2) h(-1)) and 15.1 μmol m(-2) h(-1) at the mudflat (ranged from 6.6 to 26.5 μmol m(-2) h(-1)). Annual average denitrification rate is higher at mashes than at mudflat, but without a significant difference (p = 0.084, paired t test.). Taking into account the vegetation and water area of the reservoir, a total 1.42 × 10(8) g N could be converted into nitrogen gas (N2) annually by the sediment, which is 97.7 % of the dissolved inorganic nitrogen input through precipitation. Denitrification in reservoir sediment can control the bioavailable nitrogen level of the water body. At the Yangtze estuary, denitrification primarily took place in the top 4 cm of sediment, and there was no significant spatial or temporal variation of denitrification during the year at the marshes and mudflat, which led to no single factor determining the denitrification process but the combined effects of the environmental factors, hydrologic condition, and wetland vegetation.

  3. An investigation into the effects of silver nanoparticles on antibiotic resistance of naturally occurring bacteria in an estuarine sediment.

    PubMed

    Mühling, Martin; Bradford, Adam; Readman, James W; Somerfield, Paul J; Handy, Richard D

    2009-12-01

    The aim of this study was to test whether silver nanoparticles (Ag-NPs) released into estuarine environments result in increased antibiotic resistance amongst the natural bacterial population in estuarine sediments. A 50-day microcosm exposure experiment was carried out to investigate the effects of Ag-NPs (50 nm average diameter) on the antibiotic resistance of bacteria in sediments from an estuary in southwest England. Experimental microcosms were constructed using 3.5 kg sediment cores with 20 l of overlaying seawater treated with (final) Ag-NPs concentrations of 0, 50 or 2000 microg l(-1) (n=3). Sediment samples were screened at the end of the exposure period for the presence of bacteria resistant to eight different antibiotics. Multivariate statistical analyses showed that there was no increase in antibiotic resistance amongst the bacterial population in the sediment due to the dosing of the microcosms with Ag-NPs. This study indicates that, under the tested conditions, Ag-NPs released into the coastal marine environment do not increase antibiotic resistance among naturally occurring bacteria in estuarine sediments. These results contrast previous findings where antimicrobial effects of Ag-NPs on key bacterial species in laboratory experiments have been demonstrated, and reasons for this are discussed. The negligible effects demonstrated on bacterial populations under the selected estuarine conditions, provide important information on no observed effect concentrations (NOECs) for environmental regulation.

  4. Contamination of estuarine water, biota, and sediment by halogenated organic compounds: A field study

    USGS Publications Warehouse

    Pereira, W.E.; Rostad, C.E.; Chiou, C.T.; Brinton, T.I.; Barber, L.B.; Demcheck, D.K.; Demas, C.R.

    1988-01-01

    Studies conducted in the vicinity of an industrial outfall in the Calcasieu River estuary, Louisiana, have shown that water, bottom and suspended sediment, and four different species of biota are contaminated with halogenated organic compounds (HOC) including haloarenes. A "salting-out" effect in the estuary moderately enhanced the partitioning tendency of the contaminants into biota and sediments. Contaminant concentrations in water, suspended sediments, and biota were found to be far below the values predicted on the basis of the assumption of phase equilibria with respect to concentrations in bottom sediment. Relative concentration factors of HOC between biota (catfish) and bottom sediment increased with increasing octanol/estuarine water partition coefficients (Kow*), maximizing at log Kow* of about 5, although these ratios were considerably less than equilibrium values. In contrast, contaminant concentrations in water, biota, and suspended sediments were much closer to equilibrium values. Bioconcentration factors of HOC determined on the basis of lipid content for four different biotic species correlated reasonably well with equilibrium triolein/water partition coefficients (Ktw).

  5. A microcosm approach to evaluate the degradation of tributyltin (TBT) by Aeromonas molluscorum Av27 in estuarine sediments.

    PubMed

    Cruz, Andreia; Henriques, Isabel; Sousa, Ana C A; Baptista, Inês; Almeida, Adelaide; Takahashi, Shin; Tanabe, Shinsuke; Correia, António; Suzuki, Satoru; Anselmo, Ana Maria; Mendo, Sónia

    2014-07-01

    Tributyltin (TBT) is a biocide extremely toxic to a wide range of organisms, which has been used for decades in antifouling paints. Despite its global ban in 2008, TBT is still a problem of great concern due to the high levels trapped in sediments. Aeromonas molluscorum Av27 is a TBT degrading bacterium that was isolated from an estuarine system. We investigated the ability and the role of this bacterium on TBT degradation in this estuarine system, using a microcosm approach in order to mimic environmental conditions. The experiment was established and followed for 150 days. Simultaneously, changes in the indigenous bacterial community structure were also investigated. The results revealed a maximum TBT degradation rate of 28% accompanied by the detection of the degradation products over time. Additionally, it was observed that TBT degradation was significantly enhanced by the presence of Av27. In addition a significantly higher TBT degradation occurred when the concentration of Av27 was higher. TBT degradation affected the bacterial community composition as revealed by the changes in the prevalence of Proteobacteria subdivisions, namely the increase of Deltaproteobacteria and the onset of Epsilonproteobacteria. However, the addition of Av27 strain did not affect the dominant phylotypes. Total bacterial number, bacterial biomass productivity, 16S rRNA gene and denaturing gradient gel electrophoresis (DGGE) analyses also indicated alterations on the bacterial community structure over time, with bacteria non-tolerant to pollutants increasing their representativeness, as, for instance, the increase of the number of Alphaproteobacteria clones from 6% in the beginning to 12% at the end of the experiment. The work herein presented confirms the potential of Av27 strain to be used in the decontamination of TBT-polluted environments.

  6. Large-scale spatial patterns in estuaries: estuarine macrobenthic communities in the Schelde estuary, NW Europe

    NASA Astrophysics Data System (ADS)

    Ysebaert, T.; Herman, P. M. J.; Meire, P.; Craeymeersch, J.; Verbeek, H.; Heip, C. H. R.

    2003-05-01

    Few macrobenthic studies have dealt simultaneously with the two major gradients in estuarine benthic habitats: the salinity gradient along the estuary (longitudinal) and the gradients from high intertidal to deep subtidal sites (vertical gradient). In this broad-scale study, a large data set (3112 samples) of the Schelde estuary allowed a thorough analysis of these gradients, and to relate macrobenthic species distributions and community structure to salinity, depth, current velocities and sediment characteristics. Univariate analyses clearly revealed distinct gradients in diversity, abundance, and biomass along the vertical and longitudinal gradients. In general, highest diversity and biomass were observed in the intertidal, polyhaline zone and decreased with decreasing salinity. Abundance did not show clear trends and varied between spring and autumn. In all regions, very low values for all measures were observed in the subtidal depth strata. Abundance in all regions was dominated by both surface deposit feeders and sub-surface deposit feeders. In contrast, the biomass of the different feeding guilds showed clear gradients in the intertidal zone. Suspension feeders dominated in the polyhaline zone and showed a significant decrease with decreasing salinity. Surface deposit feeders and sub-surface deposit feeders showed significantly higher biomass values in the polyhaline zone as compared with the mesohaline zone. Omnivores showed an opposite trend. Multivariate analyses showed a strong relationship between the macrobenthic assemblages and the predominant environmental gradients in the Schelde estuary. The most important environmental factor was depth, which reflected also the hydrodynamic conditions (current velocities). A second gradient was related to salinity and confirms the observations from the univariate analyses. Additionally, sediment characteristics (mud content) explained a significant part of the macrobenthic community structure not yet explained by

  7. Partitioning of metals in different binding phases of tropical estuarine sediments: importance of metal chemistry.

    PubMed

    Chakraborty, Parthasarathi; Chakraborty, Sucharita; Vudamala, Krushna; Sarkar, Arindam; Nath, B Nagender

    2016-02-01

    Distribution of metals in different binding phases of estuarine sediments provides chemically significant description of metal-sediment interactions. This study describes the influences of ligand field stabilization energy (LFSE), Jahn-Teller effect, and water exchange rate (k-w) on metal distribution in different binding phases of estuarine sediments. It was found that Cu had highest affinity for organic binding phases in the studied sediments followed by Ni and Pb. However, Pb showed strong association with Fe/Mn oxide phases followed by Ni and Cu. Faster k-w of Cu (II) (1 × 10(9) s(-1)) increased the rate of complex formation of Cu(2+) ion with ligand in the organic phases. The Cu-ligand (from organic phase) complexes gained extra stability by the Jahn-Teller effect. The combined effects of these two phenomena and high ionic potential increased the association of Cu with the organic phases of the sediments than Ni and Pb. The smaller ionic radii of Ni(2+) (0.72 Å) than Pb(2+) (1.20 Å) increase the stability of Ni-ligand complexes in the organic phase of the sediments. High LFSE of Ni(II) (compared with Pb(2+) ions) also make Ni-organic complexes increasingly stable than Pb. High k-w (7 × 10(9) s(-1)) of Pb did not help it to associate with organic phases in the sediments. The high concentration of Pb in the Fe/Mn oxyhydroxide binding phase was probably due to co-precipitation of Pb(2+) and Fe(3+). High surface area or site availability for Pb(2+) ion on Fe oxyhydroxide phase was probably responsible for the high concentration of Pb in Fe/Mn oxyhydroxide phase. Increasing concentrations of Cu in organic phases with the increasing Cu loading suggest that enough binding sites were available for Cu in the organic binding phases of the sediments. This study also describes the influence of nature of sedimentary organic carbon (terrestrial and marine derived OC) in controlling these metal distribution and speciation in marine sediment.

  8. Comparisons of 210Pb and pollen methods for determining rates of estuarine sediment accumulation

    NASA Astrophysics Data System (ADS)

    Brush, Grace S.; Martin, E. Ann; DeFries, Ruth S.; Rice, Cynthia A.

    1982-09-01

    Comparisons of sedimentation rates obtained by 210Pb and pollen analyses of 1-m cores collected throughout the Potomac Estuary show good agreement in the majority of cores that can be analyzed by both methods. Most of the discrepancy between the methods can be explained by the analytical precision of the 210Pb method and by the exactness with which time horizons can be identified and dated for the pollen method. X-radiographs of the cores and the distinctness of the pollen horizons preclude significant displacement by reworking and/or mixing of sediments. Differences between the methods are greatest where uncertainties exist in assigning a rate by one or both methods (i.e., 210Pb trends and/or "possible" horizon assignments). Both methods show the same relative rates, with greater sediment accumulation more common in the upper and middle estuary and less toward the mouth. The results indicate that geochronologic studies of estuarine sediments should be preceded by careful observation of sedimentary structures, preferably by X-radiography, to evaluate the extent of mixing of the sediments. Time horizons, whether paleontologic or isotopic, are generally blurred where mixing has occurred, precluding precise identification. Whenever possible, two methods should be used for dating sediments because a rate, albeit erroneous, can be obtained isotopically in sediments that are mixed; accurate sedimentation rates are also difficult to determine where the time boundary is a zone rather than a horizon, where the historical record does not provide a precise date for the pollen horizon, or where scouring has removed some of the sediment above a dated pollen horizon.

  9. Oxidative transformation of iron monosulfides and pyrite in estuarine sediments: Implications for trace metals mobilisation.

    PubMed

    Choppala, Girish; Bush, Richard; Moon, Ellen; Ward, Nicholas; Wang, Zhaohui; Bolan, Nanthi; Sullivan, Leigh

    2017-01-15

    Iron monosulfides are the initial iron sulfide minerals that form under reducing conditions in organic-rich sediments. Frequently referred as monosulfidic black ooze (MBO), these sediments exists in a range of anoxic systems including estuaries, coastal wetlands and permeable reactive barriers. The objective of this study was to investigate the transformation of solid phase sulfur, iron fractions and trace metals mobilisation in organic-rich hypersulfidic sediments during dredging. Two sediments from geographically contrasting sites in the Peel-Harvey Estuary were collected and subjected to oxidation through resuspension over 14 days. During oxidation, redox potential rapidly and continuously increased, although minimal change in pH was observed in both sediments. The majority of FeS was oxidised within 48 h. Although not as dynamic as FeS, unusually high rates of FeS2 oxidation were measured in both sediments at circumneutral pH, with between 39 and 58% of FeS2 oxidised over 14 days. The rapid oxidation of FeS2 may be attributed to the presence of nano-size FeS2 crystals (≈550-860 nm) with a high surface area. Before resuspension, solid bound Fe(total) was most abundant as measured by HCl-extractable Fe(II), followed by organic bound Fe(total) and oxide bound Fe(total). There was a marked decrease in these three fractions in both sediments during resuspension, with an increase in Fe(III) fraction. No significant release of trace metals was observed during resuspension of sulfidic sediments. However, disturbance to these estuarine sediments increases Fe(III) formation and further deteriorates the environment through smothering biological surfaces, deteriorating food sources and the quality of benthic habitats. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Comparisons of 210Pb and pollen methods for determining rates of estuarine sediment accumulation

    USGS Publications Warehouse

    Brush, G.S.; Martin, E.A.; DeFries, R.S.; Rice, C.A.

    1982-01-01

    Comparisons of sedimentation rates obtained by 210Pb and pollen analyses of 1-m cores collected throughout the Potomac Estuary show good agreement in the majority of cores that can be analyzed by both methods. Most of the discrepancy between the methods can be explained by the analytical precision of the 210Pb method and by the exactness with which time horizons can be identified and dated for the pollen method. X-radiographs of the cores and the distinctness of the pollen horizons preclude significant displacement by reworking and/or mixing of sediments. Differences between the methods are greatest where uncertainties exist in assigning a rate by one or both methods (i.e., 210Pb trends and/or "possible" horizon assignments). Both methods show the same relative rates, with greater sediment accumulation more common in the upper and middle estuary and less toward the mouth. The results indicate that geochronologic studies of estuarine sediments should be preceded by careful observation of sedimentary structures, preferably by X-radiography, to evaluate the extent of mixing of the sediments. Time horizons, whether paleontologic or isotopic, are generally blurred where mixing has occurred, precluding precise identification. Whenever possible, two methods should be used for dating sediments because a rate, albeit erroneous, can be obtained isotopically in sediments that are mixed; accurate sedimentation rates are also difficult to determine where the time boundary is a zone rather than a horizon, where the historical record does not provide a precise date for the pollen horizon, or where scouring has removed some of the sediment above a dated pollen horizon. ?? 1982.

  11. Habitat loss and gain: Influence on habitat attractiveness for estuarine fish communities

    NASA Astrophysics Data System (ADS)

    Amorim, Eva; Ramos, Sandra; Elliott, Michael; Franco, Anita; Bordalo, Adriano A.

    2017-10-01

    Habitat structure and complexity influence the structuring and functioning of fish communities. Habitat changes are one of the main pressures affecting estuarine systems worldwide, yet the degree and rate of change and its impact on fish communities is still poorly understood. In order to quantify historical modifications in habitat structure, an ecohydrological classification system using physiotopes, i.e. units with homogenous abiotic characteristics, was developed for the lower Lima estuary (NW Portugal). Field data, aerial imagery, historical maps and interpolation methods were used to map input variables, including bathymetry, substratum (hard/soft), sediment composition, hydrodynamics (current velocity) and vegetation coverage. Physiotopes were then mapped for the years of 1933 and 2013 and the areas lost and gained over the 80 years were quantified. The implications of changes for the benthic and demersal fish communities using the lower estuary were estimated using the attractiveness to those communities of each physiotope, while considering the main estuarine habitat functions for fish, namely spawning, nursery, feeding and refuge areas and migratory routes. The lower estuary was highly affected due to urbanisation and development and, following a port/harbour expansion, its boundary moved seaward causing an increase in total area. Modifications led to the loss of most of its sandy and saltmarsh intertidal physiotopes, which were replaced by deeper subtidal physiotopes. The most attractive physiotopes for fish (defined as the way in which they supported the fish ecological features) decreased in area while less attractive ones increased, producing an overall lower attractiveness of the studied area in 2013 compared to 1933. The implications of habitat alterations for the fish using the estuary include potential changes in the nursery carrying capacity and the functioning of the fish community. The study also highlighted the poor knowledge of the impacts of

  12. Arsenic fractionation in estuarine sediments: Does coastal eutrophication influence As behavior?

    PubMed

    Sá, Fabian; Sanders, Christian J; Patchineelam, Sambasiva Rao; Machado, Eunice da Costa; Lombardi, Ana Teresa

    2015-07-15

    The Paranaguá Estuarine Complex (PEC) includes the naturally oligotrophic (NO) Mel Island which is surrounded by sea grasses, a naturally eutrophic (NE) Benito Inlet adjacent to mangrove wetlands and the highly impacted eutrophic (IE) Paranaguá Bay, home of one of Brazil's largest ports. The results from this study indicate that reactive As and pyrite increase with sediment depth near Paranaguá port in the IE region. At the NE region, near a mangrove fringe, the reactive As, Fe, Mn and pyrite remained relatively high along the sediment column while near the sea grasses at NO the As contents were low. The degree of trace metal pyritization (DTMP) and the degree of pyritization (DOP) was highest at the IE site, slightly increasing with depth. These baseline results indicate that influence of trophic conditions and presence of marine vegetation may be directly related to As behavior in coastal systems. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Contrasting relationships between biogeochemistry and prokaryotic diversity depth profiles along an estuarine sediment gradient.

    PubMed

    O'Sullivan, Louise A; Sass, Andrea M; Webster, Gordon; Fry, John C; Parkes, R John; Weightman, Andrew J

    2013-07-01

    Detailed depth profiles of sediment geochemistry, prokaryotic diversity and activity (sulphate reduction and methanogenesis) were obtained along an estuarine gradient from brackish to marine, at three sites on the Colne estuary (UK). Distinct changes in prokaryotic populations [Archaea, Bacteria, sulphate-reducing bacteria (SRB) and methanogenic archaea (MA)] occurred with depth at the two marine sites, despite limited changes in sulphate and methane profiles. In contrast, the brackish site exhibited distinct geochemical zones (sulphidic and methanic) yet prokaryotic depth profiles were broadly homogenous. Sulphate reduction rates decreased with depth at the marine sites, despite nonlimiting sulphate concentrations, and hydrogenotrophic methanogenic rates peaked in the subsurface. Sulphate was depleted with depth at the brackish site, and acetotrophic methanogenesis was stimulated. Surprisingly, sulphate reduction was also stimulated in the brackish subsurface; potentially reflecting previous subsurface seawater incursions, anaerobic sulphide oxidation and/or anaerobic oxidation of methane coupled to sulphate reduction. Desulfobulbaceae, Desulfobacteraceae, Methanococcoides and members of the Methanomicrobiales were the dominant SRB and MA. Methylotrophic Methanococcoides often co-existed with SRB, likely utilising noncompetitive C1-substrates. Clear differences were found in SRB and MA phylotype distribution along the estuary, with only SRB2-a (Desulfobulbus) being ubiquitous. Results indicate a highly dynamic estuarine environment with a more complex relationship between prokaryotic diversity and sediment geochemistry, than previously suggested.

  14. Recovery and validation of historical sediment quality data from coastal and estuarine areas: An integrated approach

    USGS Publications Warehouse

    Manheim, F. T.; Buchholtz ten Brink, M. R.; Mecray, E.L.

    1999-01-01

    A comprehensive database of sediment chemistry and environmental parameters has been compiled for Boston Harbor and Massachusetts Bay. This work illustrates methodologies for rescuing and validating sediment data from heterogeneous historical sources. It greatly expands spatial and temporal data coverage of estuarine and coastal sediments. The database contains about 3500 samples containing inorganic chemical, organic, texture and other environmental data dating from 1955 to 1994. Cooperation with local and federal agencies as well as universities was essential in locating and screening documents for the database. More than 80% of references utilized came from sources with limited distribution (gray literature). Task sharing was facilitated by a comprehensive and clearly defined data dictionary for sediments. It also served as a data entry template and flat file format for data processing and as a basis for interpretation and graphical illustration. Standard QA/QC protocols are usually inapplicable to historical sediment data. In this work outliers and data quality problems were identified by batch screening techniques that also provide visualizations of data relationships and geochemical affinities. No data were excluded, but qualifying comments warn users of problem data. For Boston Harbor, the proportion of irreparable or seriously questioned data was remarkably small (<5%), although concentration values for metals and organic contaminants spanned 3 orders of magnitude for many elements or compounds. Data from the historical database provide alternatives to dated cores for measuring changes in surficial sediment contamination level with time. The data indicate that spatial inhomogeneity in harbor environments can be large with respect to sediment-hosted contaminants. Boston Inner Harbor surficial sediments showed decreases in concentrations of Cu, Hg, and Zn of 40 to 60% over a 17-year period.A comprehensive database of sediment chemistry and environmental

  15. Molecular responses of European flounder (Platichthys flesus) chronically exposed to contaminated estuarine sediments.

    PubMed

    Williams, Tim D; Davies, Ian M; Wu, Huifeng; Diab, Amer M; Webster, Lynda; Viant, Mark R; Chipman, J Kevin; Leaver, Michael J; George, Stephen G; Moffat, Colin F; Robinson, Craig D

    2014-08-01

    Molecular responses to acute toxicant exposure can be effective biomarkers, however responses to chronic exposure are less well characterised. The aim of this study was to determine chronic molecular responses to environmental mixtures in a controlled laboratory setting, free from the additional variability encountered with environmental sampling of wild organisms. Flounder fish were exposed in mesocosms for seven months to a contaminated estuarine sediment made by mixing material from the Forth (high organics) and Tyne (high metals and tributyltin) estuaries (FT) or a reference sediment from the Ythan estuary (Y). Chemical analyses demonstrated that FT sediment contained significantly higher concentrations of key environmental pollutants (including polycyclic aromatic hydrocarbons (PAHs), chlorinated biphenyls and heavy metals) than Y sediment, but that chronically exposed flounder showed a lack of differential accumulation of contaminants, including heavy metals. Biliary 1-hydroxypyrene concentration and erythrocyte DNA damage increased in FT-exposed fish. Transcriptomic and (1)H NMR metabolomic analyses of liver tissues detected small but statistically significant alterations between fish exposed to different sediments. These highlighted perturbance of immune response and apoptotic pathways, but there was a lack of response from traditional biomarker genes. Gene-chemical association annotation enrichment analyses suggested that polycyclic aromatic hydrocarbons were a major class of toxicants affecting the molecular responses of the exposed fish. This demonstrated that molecular responses of sentinel organisms can be detected after chronic mixed toxicant exposure and that these can be informative of key components of the mixture.

  16. Mercury mobilization in estuarine sediment porewaters: a diffusive gel time-series study.

    PubMed

    Merritt, Karen A; Amirbahman, Aria

    2007-02-01

    To assess the lability of porewater and sediment solid-phase mercury (Hg), mercapto-substituted siloxane gels were deployed within the sediments of the Penobscot estuary in Maine. Gel deployments occurred in time series and at discrete sediment depths. A sediment distribution coefficient (K(D)) was estimated by modeling the resultant gel Hg uptake. For deployments > 1 day, depth-averaged gel Hg uptake was significantly greater at depth (Zone B 6-20 cm) than in the vicinity of the sediment-water interface (Zone A 0-5 cm), with uptake ultimately reaching 16.7 +/- 4.9 ng Hg g(-1) gel versus 35.5 +/- 3.8 ng Hg g(-1) gel for Zone A versus Zone B, respectively. For Zone A, a simple diffusive model adequately describes gel mass flux, suggesting that Hg repartitioning from the solid phase does not generate a net Hg source term within the time frame of gel deployment. For Zone B, model-determined values of K(D) (K(D) = 25-75) were considerably smaller than literature values typically based on total sediment Hg concentration. The magnitude of the modeled K(D) suggests that it is a small fraction of total sediment-sequestered Hg that is likely sensitive, via interaction with porewater ligands, to the presence of an external sink. These observations of low general Hg reactivity suggest that the net porewater Hg pool may be properly defined as a function of porewater ligand production. Such a definition highlights the importance of microbially mediated diagenesis in controlling Hg cycling within estuarine sediments.

  17. Abundance and Distribution of Enteric Bacteria and Viruses in Coastal and Estuarine Sediments-a Review.

    PubMed

    Hassard, Francis; Gwyther, Ceri L; Farkas, Kata; Andrews, Anthony; Jones, Vera; Cox, Brian; Brett, Howard; Jones, Davey L; McDonald, James E; Malham, Shelagh K

    2016-01-01

    The long term survival of fecal indicator organisms (FIOs) and human pathogenic microorganisms in sediments is important from a water quality, human health and ecological perspective. Typically, both bacteria and viruses strongly associate with particulate matter present in freshwater, estuarine and marine environments. This association tends to be stronger in finer textured sediments and is strongly influenced by the type and quantity of clay minerals and organic matter present. Binding to particle surfaces promotes the persistence of bacteria in the environment by offering physical and chemical protection from biotic and abiotic stresses. How bacterial and viral viability and pathogenicity is influenced by surface attachment requires further study. Typically, long-term association with surfaces including sediments induces bacteria to enter a viable-but-non-culturable (VBNC) state. Inherent methodological challenges of quantifying VBNC bacteria may lead to the frequent under-reporting of their abundance in sediments. The implications of this in a quantitative risk assessment context remain unclear. Similarly, sediments can harbor significant amounts of enteric viruses, however, the factors regulating their persistence remains poorly understood. Quantification of viruses in sediment remains problematic due to our poor ability to recover intact viral particles from sediment surfaces (typically <10%), our inability to distinguish between infective and damaged (non-infective) viral particles, aggregation of viral particles, and inhibition during qPCR. This suggests that the true viral titre in sediments may be being vastly underestimated. In turn, this is limiting our ability to understand the fate and transport of viruses in sediments. Model systems (e.g., human cell culture) are also lacking for some key viruses, preventing our ability to evaluate the infectivity of viruses recovered from sediments (e.g., norovirus). The release of particle-bound bacteria and

  18. Implications of tidally-varying bed stress and intermittent estuarine stratification on fine-sediment dynamics through the Mekong's tidal river to estuarine reach

    NASA Astrophysics Data System (ADS)

    McLachlan, R. L.; Ogston, A. S.; Allison, M. A.

    2017-09-01

    River gauging stations are often located upriver of tidal propagation where sediment transport processes and storage are impacted by widely varying ratios of marine to freshwater influence. These impacts are not yet thoroughly understood. Therefore, sediment fluxes measured at these stations may not be suitable for predicting changes to coastal morphology. To characterize sediment transport dynamics in this understudied zone, flow velocity, salinity, and suspended-sediment properties (concentration, size, and settling velocity) were measured within the tidal Sông Hậu distributary of the lower Mekong River, Vietnam. Fine-sediment aggregation, settling, and trapping rates were promoted by seasonal and tidal fluctuations in near-bed shear stress as well as the intermittent presence of a salt wedge and estuary turbidity maximum. Beginning in the tidal river, fine-grained particles were aggregated in freshwater. Then, in the interface zone between the tidal river and estuary, impeded near-bed shear stress and particle flux convergence promoted settling and trapping. Finally, in the estuary, sediment retention was further encouraged by stratification and estuarine circulation which protected the bed against particle resuspension and enhanced particle aggregation. These patterns promote mud export ( 1.7 t s-1) from the entire study area in the high-discharge season when fluvial processes dominate and mud import ( 0.25 t s-1) into the estuary and interface zone in the low-discharge season when estuarine processes dominate. Within the lower region of the distributaries, morphological change in the form of channel abandonment was found to be promoted within minor distributaries by feedbacks between channel depth, vertical mixing, and aggregate trapping. In effect, this field study sheds light on the sediment trapping capabilities of the tidal river - estuary interface zone, a relatively understudied region upstream of where traditional concepts place sites of deposition

  19. Foraminiferal Distributions, Sedimentation Rates and Patterns in the Albemarle Estuarine System, North Carolina

    NASA Astrophysics Data System (ADS)

    Vance, D. J.; Corbett, D. R.; Culver, S. J.

    2002-12-01

    The modern distribution of benthic foraminifera of the Albemarle Estuarine System (AES) has been characterized by studying 50 strategically chosen sites to provide a model for paleoenvironmental interpretations of short sediment cores (15-75 cm). Water bodies studied within the AES include Albemarle Sound, Currituck Sound, Roanoke Sound, Croatan Sound, northern Pamlico Sound, North River, Pasquotank River, Alligator River, as well as Oregon Inlet and the adjacent foreshore and shoreface of the Atlantic Ocean. Sedimentation rates in the study area have been addressed using 210Pb and 137Cs dating methods. Five foraminiferal assemblages are present: an inner estuary biofacies characterized by two dominant genera, Ammobaculites and Ammotium, with moderate percentages of Miliammina fusca and minor percentages of Ammoastuta salsa; an outer estuary biofacies characterized again by Ammobaculites and Ammotium, but with lower percentages of Miliammina fusca; a marsh shoreline biofacies characterized by a mixed assemblage dominated by Ammobaculites and Ammotium with minor to moderate percentages of adjacent marsh foraminifera; a marsh biofacies characterized by varying abundances of Ammoastuta inepta, Arenoparella mexicana, Haplophragmoides wilberti, Jadammina macrescens, Miliammina earlandi, Miliammina fusca, Tiphotrocha comprimata, Trochammina inflata, as well as the genera Ammobaculites and Ammotium; and a marine (normal salinity) biofacies characterized mainly by Elphidium excavatum and minor percentages of other elphidiids. Sedimentation rates were studied from 28 short cores taken along transects in all the major water bodies. Rates were as high as 0.45 cm/yr at the head of Albemarle Sound and as little as 0.05 cm/yr 60 km away in the eastern part of the Albemarle. The embayed tributaries exhibited sedimentation rates on the order of 0.25 cm/yr. Limited information on sedimentation rates was provided by cores in eastern sounds, which had only a few centimeters of recent

  20. Annual variability and regulation of methane and sulfate fluxes in Baltic Sea estuarine sediments

    NASA Astrophysics Data System (ADS)

    Sawicka, Joanna E.; Brüchert, Volker

    2017-01-01

    Marine methane emissions originate largely from near-shore coastal systems, but emission estimates are often not based on temporally well-resolved data or sufficient understanding of the variability of methane consumption and production processes in the underlying sediment. The objectives of our investigation were to explore the effects of seasonal temperature, changes in benthic oxygen concentration, and historical eutrophication on sediment methane concentrations and benthic fluxes at two type localities for open-water coastal versus eutrophic, estuarine sediment in the Baltic Sea. Benthic fluxes of methane and oxygen and sediment pore-water concentrations of dissolved sulfate, methane, and 35S-sulfate reduction rates were obtained over a 12-month period from April 2012 to April 2013. Benthic methane fluxes varied by factors of 5 and 12 at the offshore coastal site and the eutrophic estuarine station, respectively, ranging from 0.1 mmol m-2 d-1 in winter at an open coastal site to 2.6 mmol m-2 d-1 in late summer in the inner eutrophic estuary. Total oxygen uptake (TOU) and 35S-sulfate reduction rates (SRRs) correlated with methane fluxes showing low rates in the winter and high rates in the summer. The highest pore-water methane concentrations also varied by factors of 6 and 10 over the sampling period with the lowest values in the winter and highest values in late summer-early autumn. The highest pore-water methane concentrations were 5.7 mM a few centimeters below the sediment surface, but they never exceeded the in situ saturation concentration. Of the total sulfate reduction, 21-24 % was coupled to anaerobic methane oxidation, lowering methane concentrations below the sediment surface far below the saturation concentration. The data imply that bubble emission likely plays no or only a minor role in methane emissions in these sediments. The changes in pore-water methane concentrations over the observation period were too large to be explained by temporal

  1. Metal pollution of estuarine sediments caused by leaching of acid sulphate soils

    NASA Astrophysics Data System (ADS)

    Nordmyr, Linda; Åström, Mats; Peltola, Pasi

    2008-01-01

    This study tracks changes in metal distribution in estuarine sediments as a result of leakage from acid sulphate (AS) soil landscapes in the Boreal Zone (Finland). The main objective was to identify the impact of these nasty soils on sediment geochemistry in a biologically sensitive and shallow brackish-water estuary. In order to do this four sediment cores were sampled in a profile extending seawards from the mouth of the Vörå River, which is one of the most heavily AS soil-impacted rivers in Finland and Europe. Two of the cores were rather deep (2.5 m and 4.0 m) and the others were shallow (0.4 m and 0.8 m). The results showed that an appreciable amount of aluminium (Al), cobalt (Co), cadmium (Cd), copper (Cu), manganese (Mn), nickel (Ni) and zinc (Zn) were elevated in the surface and sub-surface of the sampled bottom sediments compared to the deeper sediment background levels. These metals are all known to be abundantly leached from the AS soils. At the site approximately 4 km away from the river mouth, the concentrations of Cd, Co, Mn, Ni and Zn were elevated 5-100 times as compared to the background levels and showed an intriguing cyclic pattern, most likely reflecting seasonal leaching dynamics in the AS soil landscapes. In contrast, metals that are not abundantly leached from AS soils, i.e. chromium (Cr), iron (Fe) and vanadium (V) had consistently low concentrations throughout all sediment cores. The elevated metal concentrations in the top layers of the sediments in the estuary are alarming. The continuous land uplift of the region combined with the episodic rapid declines in pH may result in short and long term extensive release of metals. This, in turn, may have significant effects on the trace-metal contents in the Gulf of Bothnia and the entire Baltic Sea.

  2. Occurrence of quaternary ammonium compounds (QACs) and their application as a tracer for sewage derived pollution in urban estuarine sediments.

    PubMed

    Li, Xiaolin; Luo, Xiaojun; Mai, Bixian; Liu, Jingqin; Chen, Li; Lin, Shanshan

    2014-02-01

    Particle reactive organic contaminants in estuarine sediments can lead to various environmental problems affecting ecosystem and public health. In this study, the occurrence and homologous distribution pattern of quaternary ammonium compounds (QACs) in the surficial sediments collected from the Pearl River Estuary (PRE), China were examined along with polychlorinated biphenyls (PCBs) and polybrominated diphenylethers (PBDEs). The composition pattern of the QACs was found to be uniform in most of the sediments analyzed throughout the PRE, and the average composition pattern was identical to that determined in the sewage sludge from Guangzhou, the biggest city in the PRE. Dialkyldimethylammonium compounds, the most abundant type of QACs, positively correlated to the total concentrations of PCBs and PBDEs in most of the sediments with similar composition patterns. Therefore, the QACs are proposed as potential tracers to evaluate the transport of sewage-derived pollution in estuarine environments.

  3. Toxicity and bioaccumulation of sediment-associated silver nanoparticles in the estuarine polychaete, Nereis (Hediste) diversicolor.

    PubMed

    Cong, Yi; Banta, Gary T; Selck, Henriette; Berhanu, Deborah; Valsami-Jones, Eugenia; Forbes, Valery E

    2014-11-01

    In this study, the toxicities of sediment-associated silver added to sediment as commercially available silver nanoparticles (Ag NPs, 20 and 80 nm) and aqueous Ag (AgNO3) to the estuarine polychaete, Nereis (Hediste) diversicolor, were investigated for both individual and subcellular endpoints after 10 d of exposure. Both Ag NP types were characterized in parallel to the toxicity studies and found to be polydispersed and overlapping in size. Burrowing activity decreased (marginally) with increasing Ag concentration and depended on the form of Ag added to sediment. All worms accumulated Ag regardless of the form in which it was added to the sediment, and worm size (expressed as dry weight) was found to significantly affect bioaccumulation such that smaller worms accumulated more Ag per body weight than larger worms. Lysosomal membrane permeability (neutral red retention time, NRRT) and DNA damage (comet assay tail moment and tail DNA intensity %) of Nereis coelomocytes increased in a concentration-dependent manner in all three Ag treatments. Ag NP treatments were more toxic than aqueous Ag for all toxicity endpoints, even though bioaccumulation did not differ significantly among Ag forms. No significant difference in toxicity was observed between the two Ag NP treatments which was attributed to their overlap in particle size. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Mercury contamination history of an estuarine floodplain reconstructed from a 210Pb-dated sediment core (Berg River, South Africa).

    PubMed

    Kading, T J; Mason, R P; Leaner, J J

    2009-01-01

    Mercury deposition histories have been scarcely documented in the southern hemisphere. A sediment core was collected from the ecologically important estuarine floodplain of the Berg River (South Africa). We establish the concentration of Hg in this (210)Pb-dated sediment core at <50 ng g(-1) Hg(T) throughout the core, but with 1.3 ng g(-1) methylmercury in surface sediments. The (210)Pb dating of the core provides a first record of mercury deposition to the site and reveals the onset of enhanced mercury deposition in 1970. The ratio of methylmercury to total mercury is relatively high in these sediments when compared to other wetlands.

  5. Simultaneous removal of organic carbon and nitrogen pollutants in the Yangtze estuarine sediment: The role of heterotrophic nitrifiers

    NASA Astrophysics Data System (ADS)

    Jin, Qiang; Lu, Jian; Wu, Jun; Luo, Yongming

    2017-05-01

    The Yangtze Estuary is one of the most eutrophic coastal areas in the world. The engagement of heterotrophic nitrification bacteria in the simultaneous removal of organic carbon and ammonium in the Yangtze estuarine sediment was investigated. The specific nitrification rate in the selective autotrophic nitrification inhibition treatment was about 25% of that in the control without autotrophic nitrification inhibition, suggesting that heterotrophic nitrification, in addition to autotrophic nitrification, was an important nitrification process in the sediment. The increase of heterotrophic nitrification can offset the decrease in autotrophic nitrification, which subsequently leads to the high tolerance of nitrification to the organic carbon. The number of heterotrophic nitrification bacteria was 7.1 × 107 MPN g-1 in sediment collected from Site 1 while that of autotrophic nitrification bacteria was 4.2 × 108 MPN g-1. The isolation of heterotrophic nitrification bacteria provides direct evidence of the engagement of heterotrophs in the nitrification of the Yangtze estuarine sediment. The results show that nitrification is catalyzed by both the autotrophs and the heterotrophs, indicating functional redundancy of nitrification in sediment. Since organic carbon usually coexists with ammonium, these findings indicate an alternative bioprocess for the simultaneous removal of organic carbon and ammonium in Yangtze estuarine sediment.

  6. Metal partitioning and availability in estuarine surface sediments: Changes promoted by feeding activity of Scrobicularia plana and Liza ramada

    NASA Astrophysics Data System (ADS)

    Pedro, Sílvia; Duarte, Bernardo; Reis, Givaldo; Pereira, Eduarda; Duarte, Armando C.; Costa, José Lino; Caçador, Isabel; Almeida, Pedro Raposo de

    2015-12-01

    Several works have evidenced in the past the importance and influence of plants and terrestrial invertebrates in metal availability in soils and sediments through changes in metal speciation. In contrast, the impact of estuarine invertebrates and fishes in this process has been poorly explored. The partition of metals in estuarine surface sediments was studied in a controlled environment according to four operationally defined fractions. Sediments were analyzed before and after the passage through the gut of two detritivorous species. Scrobicularia plana feeds on the bottom and suspended sediment particles through the inhalant siphon. Liza ramada is an interface feeder, filtering the superficial layer of the sediment and suspended particles in the water column. Cd, Cu and Ni bound to carbonates increased in the pellets of S. plana, compared with the ingested sediment, as did exchangeable Zn. Similarly, Cd and Zn bound to carbonates have also increased in the pellets of L. ramada; on the contrary, a decrease of Ni was observable in the pellets of this fish. The outcome of the controlled experiments pointed to a potential increase in some metals' availability in the estuarine environment, as a result of the more mobile metal forms in the excreted fecal pellets. This draws the attention to a relevant impact of the trophic activity of both species, alongside with the potential enhancement brought to it by the bioturbation promoted by them, in the role that the estuary itself has as a contaminants' buffer.

  7. Fate of Triclosan and Evidence for Reductive Dechlorination of Triclocarban in Estuarine Sediments

    PubMed Central

    Miller, Todd R.; Heidler, Jochen; Chillrud, Steven N.; DeLaquil, Amelia; Ritchie, Jerry C.; Mihalic, Jana N.; Bopp, Richard; Halden, Rolf U.

    2008-01-01

    The biocides triclosan and triclocarban are wastewater contaminants whose occurrence and fate in estuarine sediments remain unexplored. We examined contaminant profiles in 137Cs/7Be-dated sediment cores taken near wastewater treatment plants in the Chesapeake Bay watershed (CB), Maryland and Jamaica Bay (JB), New York. In JB, biocide occurrences tracked the time course of biocide usage and wastewater treatment strategies employed, first appearing in the 1950s (triclocarban) and 1960s (triclosan), and peaking in the late 1960s and 1970s (24 ± 0.54 and 0.8 ± 0.4 29 mg/kg dry weight, respectively). In CB, where time of sediment accumulation was not as well constrained by 137Cs depth profiles, triclocarban was only measurable in 137Cs bearing sediments, peaking at 3.6 ± 0.6 mg/kg midway through the core and exceeding 1 mg/kg in recent deposits. In contrast, triclosan concentrations were low or not detectable in the CB core. Analysis of CB sediment by tandem mass spectrometry produced the first evidence for complete sequential dechlorination of triclocarban to the transformation products dichloro-, monochloro-, and unsubstituted carbanilide which were detected at maxima of 15.5 ± 1.8, 4.1 ± 2.4, and 0.5 ± 0.1 mg/kg, respectively. Concentrations of all carbanilide congeners combined were correlated with heavy metals (R2 > 0.64, P<0.01), thereby identifying wastewater as the principal pathway of contamination. Environmental persistence over the past 40 years was observed for triclosan and triclocarban in JB, and for triclocarban and its diphenylurea backbone in CB sediments. PMID:18605588

  8. Isolation and characterization of Cr(VI)-reducing actinomycetes from estuarine sediments.

    PubMed

    Terahara, Takeshi; Xu, Xudan; Kobayashi, Takeshi; Imada, Chiaki

    2015-04-01

    Bioremediation technologies have strong potential use in the less costly and more environmentally friendly removal of highly toxic hexavalent-chromium (Cr(VI)) compared with physicochemical technologies. Several Cr(VI)-reducing bacteria have been isolated; however, there are few studies on Cr(VI)-resistant and Cr(VI)-reducing actinomycetes. In this study, Cr(VI)-reducing actinomycetes were screened from estuarine, marine, and terrestrial samples on the basis of Cr(VI)-resistant and Cr(VI)-reducing ability. Of the 80 Streptomyces-like strains isolated, 20 strains were found to be resistant to 50 mg/l of Cr(VI). In addition, two strains isolated from the estuarine sediment of Tokyo Bay were found to be resistant to a concentration of 150 mg/l of Cr(VI). Furthermore, one Cr(VI)-reducing strain was found to remove 60 mg/l of Cr(VI) within 1 week and was identified as Streptomyces thermocarboxydus based on 16S rRNA gene analysis. The comparative evaluation with the type strain S. thermocarboxydus NBRC 16323 showed that our isolated strain had higher ability to grow at 27 °C and reduce Cr(VI) at a NaCl concentration of 6.0 % at 27 °C compared with the type strain NBRC 16323. These results indicate that our isolated strain have a potential ability to remove Cr(VI) from contaminated, highly saline sources without heating.

  9. The effect of accidental sulphuric acid leaking on metal distributions in estuarine sediment of Patos Lagoon.

    PubMed

    Mirlean, N; Baraj, B; Niencheski, L F; Baisch, P; Robinson, D

    2001-11-01

    In August of 1998 the tanker BAHAMAS belonging to the Chem Oil Company containing 12,000 t of concentrated sulphuric acid, had an accident on board, after which estuarine water entered one of the compartments of the tanker, resulting in a vigorous exothermic reaction. The reaction of acid with the metallic interior hull of the ship and the accompanying heat and H2 production resulted in an imminent risk of explosion. To avoid an explosion, given the fact that neutralization was not possible, some of the cargo was discharged into the surrounding water. Neutralization was done in January 1999, after the acid concentration in the tanker had decreased and the concentrations of Fe, Cr and Ni remained elevated. Metal concentrations in bottom sediments showed significant modifications. Leached mercury migrated and redeposited downstream, reaching approximately 76 times the background values. Such an anomaly has a well expressed barrier character. The mechanism for redeposition of Hg and other metals probably followed the pattern: Downstream as a result of dilution and mixing with seawater the pH of acid-water increases, favouring adsorption and/or precipitation of metals. The leading edge of a geochemical barrier, at positions 7-9 of sampling sites (Fig. 1), is confirmed by pH variations in the water. The reestablishment of normal pH occurred after a short time due to the high buffering capacity of seawater and large natural dilution process. The concentration of metals in estuarine water during and after the accident showed insignificant anomalies.

  10. Microbial communities within saltmarsh sediments: Composition, abundance and pollution constraints

    NASA Astrophysics Data System (ADS)

    Machado, Ana; Magalhães, Catarina; Mucha, Ana P.; Almeida, C. Marisa R.; Bordalo, Adriano A.

    2012-03-01

    The influence of the saltmarsh plant Halimione portucaloides and the level of sediment metal contamination on the distribution of microbial communities were investigated in two Portuguese estuarine systems with different degrees of metal contamination: the Cavado (41.5 N; 8.7 W) and Sado estuaries. In the Sado, two saltmarshes were studied: Lisnave (38.4 N; 8.7 W) and Comporta (38.4 N; 8.8 W). A PCR rDNA-DGGE approach and direct microscopic counts of DAPI-stained cells were applied to study the biodiversity and abundance of prokaryotic communities. Sediment characteristics and metal concentrations (Cd, Cr, Cu, Fe, Pb, Mn, Ni and Zn) were also evaluated to identify possible environmental pollution constraints on spatial and temporal microbial dynamics. Redundancy analysis (RDA) revealed that the Lisnave saltmarsh microbial community was usually associated with a higher degree of metal contamination, especially the metal Pb. In clear contrast, the Cavado estuary microbial assemblage composition was associated with low metal concentrations but higher organic matter content. The Comporta saltmarsh bacterial community clustered in a separate branch, and was associated with higher levels of different metals, such as Ni, Cr and Zn. Additionally, the microbial community structure of the Lisnave and Cavado showed a seasonal pattern. Moreover, microbial abundance correlated negatively with metal concentrations, being higher at the Cavado estuarine site and with general higher counts in the rhizosediment. These findings suggest that increased metal concentrations negatively affect the abundance of prokaryotic cells and that saltmarsh plants may have a pivotal role in shaping the microbial community structure.

  11. Elevated levels of perfluoroalkyl substances in estuarine sediments of Charleston, SC.

    PubMed

    White, Natasha D; Balthis, Len; Kannan, Kurunthachalam; De Silva, Amila O; Wu, Qian; French, Katherine M; Daugomah, James; Spencer, Christine; Fair, Patricia A

    2015-07-15

    Urban areas are sources of perfluoroalkyl substances (PFASs) in the environment, although little is known about specific point sources and distribution of PFASs. Sentinel species, like bottlenose dolphins, are important indicators of environmental perturbations. The high PFAS levels found in dolphins inhabiting Charleston, South Carolina prompted investigation of these chemicals in this area. This study provides further evidence on the extent of contamination and potential sources of PFASs. In this study, concentrations of 11 PFASs measured in estuarine sediments collected in 2012 from the Charleston Harbor and the Ashley and Cooper Rivers (n=36) in South Carolina revealed higher levels than those reported in any other U.S. urban areas. Detectable levels were found in all sample locations with mean total PFAS concentrations of 3.79ngg(-1) (range 0.22 to 19.2ngg(-1) d.w.). Dominant compounds were perfluorooctane sulfonate (PFOS) (mean 1.52ngg(-1); range 0.09-7.37ngg(-1) d.w.), followed by perfluorodecanoate (PFDA) (mean 0.83ngg(-1); range 0.06-4.76ngg(-1) d.w.) and perfluorooctanoate (PFOA) (mean 0.42ngg(-1); range 0.02-2.52ngg(-1) d.w.). PFOS levels in sediments at 19 of 36 sites (representing 52% of the study area) exceeded the published global median PFOS sediment concentration of 0.54ngg(-1).

  12. Rapid and efficient method to extract metagenomic DNA from estuarine sediments.

    PubMed

    Shamim, Kashif; Sharma, Jaya; Dubey, Santosh Kumar

    2017-07-01

    Metagenomic DNA from sediments of selective estuaries of Goa, India was extracted using a simple, fast, efficient and environment friendly method. The recovery of pure metagenomic DNA from our method was significantly high as compared to other well-known methods since the concentration of recovered metagenomic DNA ranged from 1185.1 to 4579.7 µg/g of sediment. The purity of metagenomic DNA was also considerably high as the ratio of absorbance at 260 and 280 nm ranged from 1.88 to 1.94. Therefore, the recovered metagenomic DNA was directly used to perform various molecular biology experiments viz. restriction digestion, PCR amplification, cloning and metagenomic library construction. This clearly proved that our protocol for metagenomic DNA extraction using silica gel efficiently removed the contaminants and prevented shearing of the metagenomic DNA. Thus, this modified method can be used to recover pure metagenomic DNA from various estuarine sediments in a rapid, efficient and eco-friendly manner.

  13. Restoring sediment to compensate for human-induced erosion of an estuarine shore

    NASA Astrophysics Data System (ADS)

    Nordstrom, Karl F.; Jackson, Nancy L.; Farrell, Eugene J.; Rafferty, Patricia; Tengwall, Charles

    2016-06-01

    Shoreline erosion is often exacerbated by reduction of sediment inputs because of interference with sediment transport by human structures. We evaluate use of sediment dredged from a navigation channel to establish a feeder beach adjacent to a bulkhead as a solution for addressing erosion of landforms and habitats on sandy estuarine shores. The objectives are to determine how beach volume, position and shape within and downdrift of the fill area change and whether the volumes supplied by dredging match sediment losses caused by human actions. The fill was placed along a 75 m length of shoreline adjacent to a marina in Great South Bay at Fire Island, New York, USA. Changes in beach shape and volume were determined from topographic surveys conducted before and after fill and at half year intervals for 18 months. The quantity of fill was 1747 m3. Maximum shoreline advance due to fill emplacement was 20.7 m. The maximum volume placed at any transect was 28.6 m3 m- 1 of shoreline length. Erosion of the fill occurred rapidly, with landward migration of a conspicuous scarp. The edge of the upland 18 months after the fill was placed was up to 4.6 m farther landward than prior to the fill. Movement of sediment alongshore downdrift of the fill occurred as wave-like pulses, extending the active foreshore bayward, causing accretion of the inner low tide terrace, burying saltmarsh peat outcrops on the foreshore and creating a higher and wider overwash platform over portions of the saltmarshes. Landforms downdrift of the fill area underwent successive stages including erosion (pre-nourishment), accretion, stability (with throughput of sediment) and then erosion. Beach nourishment compensates for human-induced sediment losses. The volume of sediment added from maintenance dredging can slow the rate of erosion but may not prevent long-term shoreline retreat. Restoration and maintenance of coastal landforms and habitats to specific target states at a given location is difficult

  14. Age of Pre-late-Wisconsin Glacial-Estuarine Sedimentation, Bristol Bay, Alaska

    NASA Astrophysics Data System (ADS)

    Kaufman, Darrell S.; Forman, Steven L.; Lea, Peter D.; Wobus, Cameron W.

    1996-01-01

    Pleistocene glacial-estuarine sediment deposited in an intertidal environment of northeastern Bristol Bay, southwestern Alaska, was dated using a variety of approaches, including infrared stimulated and thermoluminescence (IRSL and TL) techniques. Analysis of modern and 14C-dated Holocene tide-flat mud demonstrates that the bulk of sediment in this environment is reset by solar radiation, thereby lending confidence to ages obtained from similar Pleistocene deposits by luminescence techniques. IRSL seems to be especially well suited for dating, with resolution on time scales of <10,000 yr. The ages of tide-flat mud of the Nushagak Formation, derived from the Ahklun Mountains to the northwest of Bristol Bay, and of Halfmoon Bay drift, derived from the Alaska Peninsula to the southeast, suggest contemporaneous glacial-estuarine deposition related to independent glacial source areas about 75,000-80,000 yr ago. This age is consistent with other geochronological data that indicate a pre-late-Wisconsin and post-substage-5e age, including nonfinite 14C ages, a lack of interglacial indicators, and Old Crow tephra (˜140,000 yr) atop the drift, normal paleomagnetic inclinations, and amino acid (isoleucine) epimerization ratios (aIle/Ile). AIle/Ile ratios in Portlandia arctica(0.052 ± 0.003) from a marine-lag horizon at South Naknek beach, which separates Halfmoon Bay drift above from older glacial-estuarine drift below, are only slightly higher than in Mya truncata(0.041 ± 0.007) from last-interglacial Pelukian deposits at Nome. As laboratory heating experiments show that the two genera epimerize at similar rates, these data imply correlation of the marine lag at South Naknek beach with Pelukian deposits. Hence, glaciers on the Alaska Peninsula experienced major pre-late-Wisconsin advances both before and after the last interglaciation. Shells reworked into Halfmoon Bay drift yield aIle/Ile ratios of 0.028 ± 0.005 for Portlandiaat Second Point and 0.027 ± 0.001 for

  15. Assessment of trace metal contamination of estuarine and marine sediments from Florida

    SciTech Connect

    Seal, T.L.; Calder, F.D.; Sloane, G.M. ); Schropp, S. ); Windom, H.L. )

    1993-03-01

    Marine scientists have emphasized the ecological health of benthic systems for years, but only recently has the threat of contaminated sediments to natural resources and human health received widespread attention. In the 1980's the Florida Department of Environmental Regulation developed an interpretive statistical tool to distinguish anthropogenic trace metal enrichment from natural chemical variability in estuarine and marine sediments of Florida. Based on normalization of metal concentrations to reference elements (aluminum or lithium), the tool allows comparison of diverse sedimentary environments. Between 1982 and 1992, samples were collected at over 680 stations. Just under 100 stations were designated as clean reference sites well removed from both point or nonpoint sources. Statistical regression and prediction limits were calculated. On a statewide bases, 4% of stations were enriched above predicted levels with As, 27% with Cd, 16% with Cr, 23% with Cu, 36% with Pb, 9% with Ni, 30% with Hg, and 34% with Zn. Significant metal contamination was detected by sediment surveys in Tampa Bay, Pensacola Bay, Biscayne Bay, and the St. Johns River. Presented in a graphical format, this method can be readily used by local, state, and federal regulatory agencies for many purposes, including monitoring, permitting, and remediation. The employment of precise and accurate analytical techniques, and uniform quality assurance procedures, is paramount in sediment monitoring studies. Multiacid (HF-HNO[sub 3]-HClO[sub 4]) digestion techniques (total digestion) were used to estimate natural versus anthropogenic trace metal burdens. The use of reference materials and laboratory intercalibration studies is required for effective comparison and trend analysis of sediment data from future monitoring studies.

  16. Shoreface to estuarine sedimentation in the late Paleocene Matanomadh Formation, Kachchh, western India

    NASA Astrophysics Data System (ADS)

    Srivastava, V. K.; Singh, B. P.

    2017-04-01

    Late Paleocene sedimentation in the pericratonic Kachchh Basin marks the initial marine transgression during the Cenozoic era. A 17 m thick sandstone-dominated succession, known as the clastic member (CM) of the Matanomadh Formation (MF), is exposed sporadically in the basin. Three facies associations are reconstructed in the succession in three different sections. Facies association-1 contains matrix-supported pebbly conglomerate facies, horizontally-laminated sandstone-mudstone alternation facies, hummocky- and swaley cross-bedded sandstone facies, wave-rippled sandstone facies and climbing ripple cross-laminated sandstone facies. This facies association developed between shoreface and foreshore zone under the influence of storms on a barrier ridge. Facies association-2 contains sigmoidal cross-bedded sandstone facies, sandstone-mudstone alternation facies, flaser-bedded sandstone facies, herringbone cross-bedded sandstone facies and tangential cross-bedded sandstone facies. This facies association possessing tidal bundles and herringbone cross-beds developed on a tidal flat with strong tidal influence. Facies association-3 comprises pebbly sandstone facies, horizontally-bedded sandstone facies, tangential cross-bedded sandstone facies exhibiting reactivation surfaces and tabular cross-bedded sandstone facies. This facies association represents sedimentation in a river-dominated estuary and reactivation surfaces and herringbone cross-beds indicating tidal influence. The bipolar paleocurrent pattern changes to unipolar up-section because of the change in the depositional currents from tidal to fluvial. The sedimentation took place in an open coast similar to the Korean coast. The presence of neap-spring tidal rhythmites further suggests that a semidiurnal system similar to the modern day Indian Ocean was responsible for the sedimentation. Here, the overall sequence developed during the transgressive phase where barrier ridge succession is succeeded by the tidal

  17. Prokaryotic Community in Lacustrine Sediments of Byers Peninsula (Livingston Island, Maritime Antarctica).

    PubMed

    Gugliandolo, Concetta; Michaud, Luigi; Lo Giudice, Angelina; Lentini, Valeria; Rochera, Carlos; Camacho, Antonio; Maugeri, Teresa Luciana

    2016-02-01

    . Ilumatobacter (Actinobacteria), Gp16 (Acidobacteria), and Gemmatimonas (Gemmatimonadetes) were recovered as dominant genera in both inland and coastal lakes, but not in the estuarine sample, indicating that they may be useful markers of Antarctic lakes. The proximity to the sea, the different lake depths and the external or internal origin of the nutrient sources shape the bacterial communities composition in lacustrine sediments of Byers Peninsula.

  18. Estuarine sediment resuspension and acidification: Release behaviour of contaminants under different oxidation levels and acid sources.

    PubMed

    Martín-Torre, M Camino; Cifrian, Eva; Ruiz, Gema; Galán, Berta; Viguri, Javier R

    2017-09-01

    Carbon dioxide (CO2) Capture and Storage (CCS) is a technology to reduce the emissions of this gas to the atmosphere by sequestering it in geological formations. In the case of offshore storage, unexpected CO2 leakages will acidify the marine environment. Reductions of the pH might be also caused by anthropogenic activities or natural events such as acid spills and dredging operations or storms and floods. Changes in the pH of the marine environment will trigger the mobilisation of elements trapped in contaminated shallow sediments with unclear redox boundary. Trace element (As, Cd, Cr, Cu, Ni, Pb and Zn) release from anoxic and oxic estuarine sediment is analysed and modelled under different laboratory acidification conditions using HNO3 (l) and CO2 (g): acidification at pH = 6.5 as worst-case scenario in events of CO2 leakages and acid spills, and acidification at pH = 7.0 as a seawater scenario under CO2 leakages, acid spills, as well as sediment resuspension. The prediction of metal leaching behaviour appear to require sediment specific and site specific tools. In the present work it is demonstrated that the proposed three in-series reactions model predicts the process kinetics of the studied elements under different simulated environmental conditions (oxidation levels and acid sources). Differences between HNO3 and CO2 acidification are analysed through the influence of the CO2 gas on the ionic competition of the medium. The acidification with CO2 provokes higher released concentrations from the oxic sediment than from the anoxic sediment, except in the case of Zn, which influences the release of the other studied elements. Slight acidification can endanger the aquatic environment through an important mobilisation of contaminants. The obtained prediction of the contaminant release from sediment (kinetic parameters and maximum concentrations) can contribute to the exposure assessment stage for risk management and preincidental planning in accidental CO2

  19. The structure of the benthic macrofaunal assemblages and sediments characteristics of the Paraguaçu estuarine system, NE, Brazil

    NASA Astrophysics Data System (ADS)

    Barros, Francisco; Hatje, Vanessa; Figueiredo, Maria Betânia; Magalhães, Wagner Ferreira; Dórea, Haroldo Silveira; Emídio, Elissandro Soares

    2008-07-01

    The structure of the benthic macrofaunal assemblages of the estuarine portion of Paraguaçu River, NE, Brazil, and its relationship with surface sediment characteristics (trace metals, PAHs, nutrients and grain size) and physical variables were investigated at ten stations on two contrasting occasions, summer (dry season) and winter (rainy season). A total of 1258 individuals (632 in winter and 626 in summer) and 62 taxa representing polychaetes, crustaceans, bivalves, echinoderms, bryozoans, sponges, cnidarians and cephalochordates were collected. Benthic assemblages in the upper estuary were unlike those in the lower estuary and a clear substitution of benthic taxa along the estuary was observed. Macrofaunal invertebrates in the low salinity region, composed of coarse sediments, were dominated by tellinids, venerids (bivalves), cirolanids (isopods), cyclopoids (copepods), and nereidids (polychaetes). While the high salinity region, composed of fine sediments, were dominated by nuculids (bivalves), cirratulids (polychaetes), and by amphiurids (ophiuroids). The Paraguaçu estuarine system is not severely affected by anthropogenic activities. In the great majority of the study sites, concentrations of trace metals and PAHs in the sediments were near background values. Nutrients values were also low. We formulated new models of taxon distribution and suggested detailed studies on the effects of salinity variation and studies using functional approaches to better understand the processes causing the spatial patterns in tropical estuarine benthic assemblages.

  20. Recent advances in the use of estuarine meiobenthos to assess contaminated sediment effects in multi-species whole sediment microcosms

    SciTech Connect

    Chandler, G.T.; Coull, B.C.; Schizas, N.V.; Donelan, T.L.

    1995-12-31

    Many marine meiobenthic taxa (i.e. invertebrates passing a 1-mm sieve but retaining on a 0.063 mm sieve) are ideal for ``whole-sediment`` and porewater bioassay of sedimented pollutants. Annual production of meiobenthos is 5--10 times that of the more commonly studied macrobenthos, and > 95% of all meiobenthos live in the oxic zone of muddy sediments at densities of 4--12 million per M{sup 2}. Most spend their entire lifecycles, burrowing freely and feeding on/within the sediment:porewater matrix, many taxa undergo 10--14 generations per year, most larval/juvenile stages are benthic, and many have easily quantifiable reproductive output. Furthermore, many meiobenthic taxa can be cultured indefinitely over multiple life-cycles within simple sediment microcosms consisting of sealed whole-sediment cores collected intact from intertidal mudflats. The authors describe several recent technical developments exploiting meiofaunal sediment culture for rapid contaminated sediment bioassays of toxicant effects on survival, reproduction and population growth of meiobenthic taxa in whole-sediment microcosms. Currently meiobenthic copepods, nematodes, foraminifers and polychaetes are being continuously cultured to study these parameters under exposure to model sediment-associated toxicants (e.g. cadmium). Bioassays are run for 21-d under flowing seawater. With this approach, fertile benthic copepods (e.g. Amphiascus tenuiremis) can be added to core microcosms to assess survival and growth of a fixed population cohort. All other meiobenthic taxa are enumerated relative to controls and evaluated for toxicant effects on higher order community-level endpoints. This approach exploits meiobenthos` high abundance and rapid reproductive rates to yield on a micro scale better endpoints than much larger sediment mesocosms targeted at macrofaunal endpoints.

  1. Inorganic As speciation and bioavailability in estuarine sediments of Todos os Santos Bay, BA, Brazil.

    PubMed

    Hatje, V; Macedo, S M; de Jesus, R M; Cotrim, G; Garcia, K S; de Queiroz, A F; Ferreira, S L C

    2010-12-01

    The spatial distribution of As (total As, As (III) and As (V)) in estuarine sediments from the main tributaries of Todos os Santos Bay, BA, Brazil, was evaluated under high and low flow conditions. The concentrations of As were determined using a slurry sampling procedure with hydride generation atomic absorption spectrometry (HG-AAS). The highest concentrations were observed at estuary mouths, and exceeded conservative lower threshold value (Threshold Effects Level; TEL). Due to the oxic conditions and abundance of Mn and Fe (oxyhydr)oxides in the sediments, most inorganic arsenic in the Subaé and Paraguaçu estuaries was present as As (V). Nevertheless, the concentration of As (III) at several locations along the Jaguaripe River were also above the TEL value, suggesting that As may be toxic to biota. In the Subaé estuary, antropogenic activities are the main source of As. At the Jaguaripe and at Paraguaçu estuaries, nevertheless, natural sources of As need to be considered to explain the distribution patterns.

  2. Tidal sedimentation from a fluvial to estuarine transition, Douglas Group, Missourian -- Virgilian, Kansas

    SciTech Connect

    Lanier, W.P. . Dept. of Earth Sciences); Feldman, H.R. . Kansas Geological Survey); Archer, A.W. . Dept. of Geology)

    1993-09-01

    The Tonganoxie Sandstone Member of the Stranger Formation (Douglas Group, Upper Pennsylvanian, Kansas) was deposited in a funnel-shaped, northeast-southwest-trending paleovalley that was incised during the uppermost Missourian sealevel lowstand and backfilled during the subsequent transgression. Quarry exposures of the Tonganoxie near Ottawa, Kansas, include [approximately] 5 m of sheetlike, vertically accreted siltstones and sandy siltstones, bounded above and below by thin coals with upright plant fossils and paleosols. Strata range from submillimeter-thick, normally graded rhythmites to graded bedsets up to 12.5 cm thick with a vertical sedimentary structure sequence (VSS) consisting of the following intervals: (A) a basal massive to normally graded interval; (B) a parallel-laminated interval; (C) a ripple-cross-laminated interval; and (D) an interval of draped lamination. The Tonganoxie succession has many similarities to fluvial overbank/floodplain deposits: sheetlike geometry, upright plant fossils, lack of bioturbation and body fossils, dominance of silt, and a punctuated style of rapid sedimentation from suspension-laden waning currents. Analysis of stratum-thickness variations through the succession suggests that tides significantly influenced sediment deposition. A fluvial-to-estuarine transitional depositional setting is interpreted for the Tonganoxie by analogy with modern depositional settings that show similar physical and biogenic sedimentary structures, vertical sequences of sedimentary structures, and aggradation rates.

  3. Natural attenuation and biosurfactant-stimulated bioremediation of estuarine sediments contaminated with diesel oil.

    PubMed

    Bayer, Débora M; Chagas-Spinelli, Alessandra C O; Gavazza, Sávia; Florencio, Lourdinha; Kato, Mario T

    2013-09-01

    We evaluated the bioremediation, by natural attenuation (NA) and by natural attenuation stimulated (SNA) using a rhamnolipid biosurfactant, of estuarine sediments contaminated with diesel oil. Sediment samples (30 cm) were put into 35 cm glass columns, and the concentrations of the 16 polycyclic aromatic hydrocarbons (PAHs) prioritized by the US Environmental Protection Agency were monitored for 111 days. Naphthalene percolated through the columns more than the other PAHs, and, in general, the concentrations of the lower molecular weight PAHs, consisting of two and three aromatic rings, changed during the first 45 days of treatment, whereas the concentrations of the higher molecular weight PAHs, consisting of four, five, and six rings, were more stable. The higher molecular weight PAHs became more available after 45 days, in the deeper parts of the columns (20-30 cm). Evidence of degradation was observed only for some compounds, such as pyrene, with a total removal efficiency of 82 and 78 % in the NA and SNA treatments, respectively, but without significant difference. In the case of total PAH removal, the efficiencies were significantly different of 82 and 67 %, respectively.

  4. Effects of Bottom-up and Top-down Controls and Climate Change on Estuarine Macrophyte Communities and the Ecosystem Services they Provide

    EPA Science Inventory

    Macrophytes provide important estuarine benthic habitats and support a significant portion of estuarine productivity. The composition and characteristics of these benthic communities are regulated bottom-up by resource availability and from the top-down by herbivory and predation...

  5. Effects of Bottom-up and Top-down Controls and Climate Change on Estuarine Macrophyte Communities and the Ecosystem Services they Provide

    EPA Science Inventory

    Macrophytes provide important estuarine benthic habitats and support a significant portion of estuarine productivity. The composition and characteristics of these benthic communities are regulated bottom-up by resource availability and from the top-down by herbivory and predation...

  6. Depositional variability of estuarine intertidal sediments and implications for metal distribution: An example from Moreton Bay (Australia)

    NASA Astrophysics Data System (ADS)

    Morelli, Guia; Gasparon, Massimo

    2015-10-01

    This study examines the patterns of depositional variability, sediment geochemistry and metal distribution in intertidal areas of Moreton Bay, southeast Queensland, Australia. Recent concern over increasing human impact on the bay has generated the need to obtain evidence on how the disturbance of the depositional setting might affect the natural estuarine environment. Sediment stratigraphy, major, and trace element analyses of sediment cores show that the sedimentation pattern is unique to each intertidal site. Disturbed 210Pb and 137Cs activity profiles of some of the cores indicate that sediment reworking occurs across the intertidal flats up to a depth of at least 80 cm. With some notable exceptions, an accurate geochronology of the surface sediments could not be established due to low 210Pb activities and sediment mixing. Thus, an increase in Pb, Zn and Cu towards the surface sediments observed at various sites is attributed to both anthropogenic contribution following the rapid urban development in the last century and to post-depositional diagenetic processes, bioturbation and sediment re-suspension induced by tides, storms or floods. Sediment cores are representative only of the local sedimentation and may not always allow extensive correlation to larger areas. Vertical profiles of heavy metals reflect the different depositional environment controlled by the complex hydrodynamics of the bay. Local hydrologic, physical, and tidal conditions might induce metals redistribution at different scales. This information is of critical importance in view of sediment remobilization caused by future development such as dredging, intertidal areas reclamation or excavation of new navigational channels.

  7. Diversity and spatial distribution of sediment ammonia-oxidizing crenarchaeota in response to estuarine and environmental gradients in the Changjiang Estuary and East China Sea.

    PubMed

    Dang, Hongyue; Zhang, Xiaoxia; Sun, Jin; Li, Tiegang; Zhang, Zhinan; Yang, Guanpin

    2008-07-01

    Ammonia-oxidizing archaea (AOA) have recently been found to be potentially important in nitrogen cycling in a variety of environments, such as terrestrial soils, wastewater treatment reactors, marine waters and sediments, and especially in estuaries, where high input of anthropogenic nitrogen is often experienced. The sedimentary AOA diversity, community structure and spatial distribution in the Changjiang Estuary and the adjacent East China Sea were studied. Multivariate statistical analysis indicated that the archaeal amoA genotype communities could be clustered according to sampling transects, and the station located in an estuarine mixing zone harboured a distinct AOA community. The distribution of AOA communities correlated significantly with the gradients of surface-water salinity and sediment sorting coefficient. The spatial distribution of putative soil-related AOA in certain sampling stations indicated a strong impact of the Changjiang freshwater discharge on the marine benthic microbial ecosystem. Besides freshwater, nutrients, organic matter and suspended particles, the Changjiang Diluted Water might also contribute to the transport of terrestrial archaea into the seawater and sediments along its flow path.

  8. Reactive iron and manganese in estuarine sediments of the Baltic Sea: Impacts of flocculation and redox shuttling

    NASA Astrophysics Data System (ADS)

    Jilbert, Tom; Tiihonen, Rosa; Myllykangas, Jukka-Pekka; Asmala, Eero; Hietanen, Susanna

    2016-04-01

    Iron (Fe) and manganese (Mn) play important roles in sedimentary carbon cycling in both freshwater and marine systems. Dissimilatory reduction of Fe and Mn oxides is known to be a major pathway of suboxic organic matter remineralization in surface sediments, while recent studies have shown that Fe and Mn oxides may be involved in the anaerobic oxidation of methane deeper in the sediment column (e.g., Egger et al., 2015). Estuaries are transitional environments, characterized by gradients of salinity and redox conditions which impact on the mobility of Fe and Mn. In turn, the distribution of Fe and Mn in estuarine sediments, and the role of the two metals in carbon cycling, is expected to be spatially heterogeneous. However, few studies have attempted to describe the sedimentary distribution of Fe and Mn in the context of processes occurring in the estuarine water column. In particular, salinity-driven flocculation and redox shuttling are two key processes whose relative impacts on sedimentary Fe and Mn have not been clearly demonstrated. In this study we investigated the coupled water column and sedimentary cycling of Fe and Mn along a 60km non-tidal estuarine transect in the Gulf of Finland, Baltic Sea. We show that riverine Fe entering the estuary as colloidal oxides associated with dissolved organic matter (DOM) is quickly flocculated and sedimented within 5 km of the river mouth, despite the shallow lateral salinity gradient. Sediments within this range are enriched in Fe (up to twice the regional average), principally in the form of crystalline Fe oxides as determined by sequential extractions. The high crystallinity implies relative maturity of the oxide mineralogy, likely due to sustained oxic conditions and long residence time in the river catchment. Despite the reducing conditions below the sediment-water interface, Fe is largely retained in the sediments close to the river mouth. In contrast, sedimentary Mn concentrations are highest in a deep silled

  9. Effects of watershed land-cover on the biogeochemical properties of estuarine tidal flat sediments: A test in a densely-populated subtropical island

    NASA Astrophysics Data System (ADS)

    Morita, Akiko; Touyama, Shouji; Kuwae, Tomohiro; Nishimura, Osamu; Sakamaki, Takashi

    2017-01-01

    The effects of watershed land cover on the biogeochemical properties of estuarine tidal flat sediment were examined in estuarine tidal flats of 16 watersheds in a densely populated, subtropical island of Japan. Despite the small sizes of the watersheds (<16.5 km2), a redundancy analysis showed that river water quality explained 62% of the cross-estuary variation in the biogeochemical properties of estuarine tidal flat sediment by the first two ordination axes. We also found that the dissolved nutrient concentrations of river water and pheophytin a content of tidal flat sediment were positively related to agricultural and urbanized land cover in the watersheds. These results indicate that human nutrient inputs significantly increase algae-derived deposits in estuaries with relatively more developed watersheds. The δ13C of particulate organic matter (POM) was negatively related to watershed forest cover. This suggests that terrestrially derived-origin POM deposits are substantial in the estuaries connected to watersheds with relatively high forest cover. However, the chemical properties of tidal flat sediment were not related to chemical indicators of POM in the base flow. We hypothesize that substantial terrestrially derived POM is discharged to estuaries of high-forest-cover watersheds during high flow, and this partially controls the chemical properties of estuarine sediments. Our results demonstrate that the chemical properties of estuarine tidal flats are associated with watershed land cover, and that the dominant processes controlling estuarine sediment properties differ among watersheds depending on land cover composition.

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

    PubMed

    Martín-Torre, M Camino; Payán, M Cruz; Verbinnen, Bram; Coz, Alberto; Ruiz, Gema; Vandecasteele, Carlo; Viguri, Javier R

    2015-04-01

    The contaminant release from estuarine sediment due to pH changes was investigated using a modified CEN/TS 14429 pH-dependence leaching test. The test is performed in the range of pH values of 0-14 using deionised water and seawater as leaching solutions. The experimental conditions mimic different circumstances of the marine environment due to the global acidification, carbon dioxide (CO2) leakages from carbon capture and sequestration technologies, and accidental chemical spills in seawater. Leaching test results using seawater as leaching solution show a better neutralisation capacity giving slightly lower metal leaching concentrations than when using deionised water. The contaminated sediment shows a low base-neutralisation capacity (BNCpH 12 = -0.44 eq/kg for deionised water and BNCpH 12 = -1.38 eq/kg for seawater) but a high acid-neutralisation capacity when using deionised water (ANCpH 4 = 3.58 eq/kg) and seawater (ANCpH 4 = 3.97 eq/kg). Experimental results are modelled with the Visual MINTEQ geochemical software to predict metal release from sediment using both leaching liquids. Surface adsorption to iron- and aluminium-(hydr)oxides was applied for all studied elements. The consideration of the metal-organic matter binding through the NICA-Donnan model and Stockholm Humic Model for lead and copper, respectively, improves the former metal release prediction. Modelled curves can be useful for the environmental impact assessment of seawater acidification due to its match with the experimental values.

  11. Evidence of annual variations in sediment supply to the Illinois Basin in Lower Pennsylvanian estuarine tidalites

    SciTech Connect

    Kvale, E.P.; Fraser, G.S. ); Zawistoski, A. ); Archer, A.W. )

    1992-01-01

    The intertidal to subtidal estuarine deposits in the early Pennsylvanian (Morrowan) Hindostan whetstone beds of Indiana consist of finely laminated siltstones with very thin intercalated claystone drapes. The laminae are grouped into millimeter-scale tidal bundles that thicken and thin in a vertical sequence that reflect a hierarchy of semidaily, daily, fortnightly, and monthly tidal cycles that are superposed on yearly cycles. The yearly pattern is recognized as a progressive thickening and thinning of neap-neap (semi-monthly) intervals. This yearly cyclicity provides a finite, short-term time element against which rates, duration, and timing of other geologic processes may be determined. Tidal theory predicts two equivalent neap-neap maxima per year, but all of the nine yearly cycles preserved in the whetstone beds contain one dominant maximum and one subordinant maximum. The Illinois Basin lay at 5[degree] south latitude during the Early Pennsylvanian, but presently, such equatorial zones are characterized by a uniform annual rainfall regime. The annual change in sedimentation patterns interpreted for the whetstone beds could be explained in several ways: (1) shifts in the intertropical convergence Zone may have resulted from substantial seasonal changes in latitudinal pressure variations brought about by the extreme concentration of land mass (Gondwanaland) in south arctic latitudes during the early Pennsylvanian; (2) shifts in westerly wind flow off the Tethys Ocean, across the Appalachian mountains and into the Illinois Basin, may also have produced seasonal rainfall patterns; or (3) the bulk of the sediment yield to the Illinois Basin came from relatively less vegetated source areas in higher latitudes and/or elevations that experienced strong seasonal variations in precipitation, and that relatively little sediment was contributed by the heavily vegetated parts of the drainage basin in the lower latitudes.

  12. Seagrass sediments reveal the long-term deterioration of an estuarine ecosystem.

    PubMed

    Serrano, Oscar; Lavery, Paul; Masque, Pere; Inostroza, Karina; Bongiovanni, James; Duarte, Carlos

    2016-04-01

    The study of a Posidonia australis sediment archive has provided a record of ecosystem dynamics and processes over the last 600 years in Oyster Harbour (SW Australia). Ecosystem shifts are a widespread phenomenon in coastal areas, and this study identifies baseline conditions and the time-course of ecological change (cycles, trends, resilience and thresholds of ecosystem change) under environmental stress in seagrass-dominated ecosystem. The shifts in the concentrations of chemical elements, carbonates, sediments <0.125 mm and stable carbon isotope signatures (δ(13) C) of the organic matter were detected between 1850s and 1920s, whereas the shift detected in P concentration occurred several decades later (1960s). The first degradation phase (1850s-1950s) follows the onset of European settlement in Australia and was characterized by a strong increase in sediment accumulation rates and fine-grained particles, driven primarily by enhanced run-off due to land clearance and agriculture in the catchment. About 80% of total seagrass area at Oyster Harbour was lost during the second phase of environmental degradation (1960s until present). The sharp increase in P concentration and the increasing contribution of algae and terrestrial inputs into the sedimentary organic matter pool around 1960s provides compelling evidence of the documented eutrophication of the estuary and the subsequent loss of seagrass meadows. The results presented demonstrate the power of seagrass sedimentary archives to reconstruct the trajectories of anthropogenic pressures on estuarine ecosystem and the associated regime shifts, which can be used to improve the capacity of scientists and environmental managers to understand, predict and better manage ecological change in these ecosystems.

  13. Estuarine sedimentation, sediment character, and foraminiferal distribution in central San Francisco Bay, California

    USGS Publications Warehouse

    Chin, John L.; Woodrow, Donald L.; McGann, Mary; Wong, Florence L.; Fregoso, Theresa; Jaffe, Bruce E.

    2010-01-01

    Central San Francisco Bay is the deepest subembayment in the San Francisco Bay estuary and hence has the largest water volume of any of the subembayments. It also has the strongest tidal currents and the coarsest sediment within the estuary. Tidal currents are strongest over the west-central part of central bay and, correspondingly, this area is dominated by sand-size sediment. Much of the area east of a line from Angel Island to Alcatraz Island is characterized by muddy sand to sandy mud, and the area to the west of this line is sandy. The sand-size sediment over west-central bay furthermore is molded by the energetic tidal currents into bedforms of varying sizes and wavelengths. Bedforms typically occur in water depths of 15-25 m. High resolution bathymetry (multibeam) from 1997 and 2008 allow for subdivision of the west-central bayfloor into four basic types based on morphologic expression: featureless, sand waves, disrupted/man-altered, and bedrock knobs. Featureless and sand-wave morphologies dominate the bayfloor of west-central bay. Disrupted bayfloor has a direct association with areas that are undergoing alteration due to human activities, such as sand-mining lease areas, dredging, and disposal of dredge spoils. Change detection analysis, comparing the 1997 and 2008 multibeam data sets, shows that significant change has occurred in west-central bay during the roughly 10 years between surveys. The surveyed area lost about 5.45 million m3 of sediment during the decade. Sand-mining lease areas within west-central bay lost 6.77 million m3 as the bayfloor deepened. Nonlease areas gained 1.32 million m3 of sediment as the bayfloor shallowed slightly outside of sand-mining lease areas. Furthermore, bedform asymmetry did not change significantly, but some bedforms did migrate some tens of meters. Gravity cores show that the area east of Angel and Alcatraz Islands is floored by clayey silts or silty sand whereas the area to the west of the islands is floored

  14. Lateral trends and vertical sequences in estuarine sediments, Willapa Bay, Washington

    USGS Publications Warehouse

    Clifton, H. Edward; Phillips, L.

    1980-01-01

    Willapa Bay is a sizable estuary on the southern coast of Washington- Relatively unmodified in a geologic sense by human activity the bay provides an excellent example of modern depositional facies in an estuarine setting. Studies of these deposits indicate that consistent lateral trends exist in sediment texture and sedimentary structures. The texture changes from sandy at the mouth of the bay to muddy in its upper parts. In any part of the bay , sediment is coarsest in the channel bottoms, where lag deposits accumulate. The sediment tends to fine in an upslope direction and is finest in supratidal flat deposits of silt and clay. The nature of sedimentary structures depends on the combination of physical and biological processes and sediment textures. Bedforms exist wherever the bed is sandy. In the main tidal channels sandwaves and dunes up to 4 meters high occur. In tributary channels and at the margins of the main channel, at shallower depths and under less intense currents , the structures are generally less than a meter high. Current ripples occur in t he sandy bed of all of the tidal channels and in runoff channels cross the tidal flat. Symmetric long-crested ripples are produced by wave action over the sandy intertidal flat. Internal structures in the bay's sediment depend not only on the nature of the bedform but also on the rate of bioturbation relative to physical processes. Under fields of large sandwaves or dunes, medium- to large-scale tabular and trough crossbedding predominates. This crossbedding generally is unidirectional, reflecting the locally dominant current (ebb or flood). Ripple bedding predominates elsewhere in sandy sediment within the channels. Where sand transport is diminished, as on the floor of the upper tributary channels, bioturbation exceeds the rate of production of physical structures and bedding is destroyed. The depositional banks in such areas tend to be sites of rapid sediment accumulation and bedding in the form of

  15. Primary effects of extracellular enzyme activity and microbial community on carbon and nitrogen mineralization in estuarine and tidal wetlands.

    PubMed

    Li, Xiaofei; Hou, Lijun; Liu, Min; Lin, Xianbiao; Li, Ye; Li, Shuwen

    2015-03-01

    Estuarine and tidal wetlands with high primary productivity and biological activity play a crucial role in coastal nutrient dynamics. Here, to better reveal the effects of extracellular enzymes and microbial community on carbon (C) and nitrogen (N) mineralization, the incubation experiments with different C and N addition patterns to the tidal sediments of the Yangtze Estuary (China) were conducted. The results suggested a significant increase in cumulative CO2 effluxes in the C and CN treatment experiments, while no significant difference in cumulative CO2 effluxes between the N treatment and control (CK) experiments was observed. In addition, the nutrient addition patterns had a great influence on dissolve organic C and N levels, but a small effect on microbial biomass C and N. Microbial community composition and microbial activity were found to be positively correlated with organic C (OC) and the molar ratio of C to N (C/N). Partial correlation analysis, controlling for C/N, supported direct effects of OC on the activity of carbon-cycling extracellular enzymes (cellulase and polyphenol oxidase), while C/N exhibited negatively correlations with urease and Gram-positive bacteria to Gram-negative bacteria (G+/G-). Strong relationships were found between CO2 efflux and mineral nitrogen with the activity of specific enzymes (sucrase, cellulase, and polyphenol oxidase) and abundances of Gram-negative bacteria, arbuscular mycorrhizal fungi, and fungi, suggesting the significant influences of microbial community and enzyme activity on C and N mineralization in the estuarine and tidal wetlands. Furthermore, this study could highlight the need to explore effects of nutrient supply on microbial communities and enzyme activity changes associated with the C and N mineralization in these wetlands induced by the climate change.

  16. Radioactive impact in sediments from an estuarine system affected by industrial wastes releases.

    PubMed

    Bolívar, Juan Pedro; García-Tenorio, Rafael; Mas, José Luis; Vaca, Federico

    2002-03-01

    A big fertilizer industrial complex and a vast extension of phosphogypsum piles (12 km2), sited in the estuary formed by the Odiel and Tinto river mouths (southwest of Spain), are producing an unambiguous radioactive impact in their surrounding aquatic environment through radionuclides from the U-series. The levels and distribution of radionuclides in sediments from this estuarine system have been determined. The analyses of radionuclide concentrations and activity ratios have provided us with an interesting information to evaluate the extension, degree and routes of the radioactive impact, as well as for the knowledge of the different pathways followed for the radioactive contamination to disturb this natural system. The obtained results indicate that the main pathway of radioactive contamination of the estuary is through the dissolution in its waters of the radionuclides released by the industrial activities and their later fixation on the particulate materials. Tidal activity also plays an important role in the transport and homogenization along the estuary of the radioactivity released from the fertilizer plants.

  17. Trace metal behaviour in estuarine and riverine floodplain soils and sediments: a review.

    PubMed

    Du Laing, G; Rinklebe, J; Vandecasteele, B; Meers, E; Tack, F M G

    2009-06-15

    This paper reviews the factors affecting trace metal behaviour in estuarine and riverine floodplain soils and sediments. Spatial occurrence of processes affecting metal mobility and availability in floodplains are largely determined by the topography. At the oxic-anoxic interface and in the anoxic layers of floodplain soils, especially redox-sensitive processes occur, which mainly result in the inclusion of metals in precipitates or the dissolution of metal-containing precipitates. Kinetics of these processes are of great importance for these soils as the location of the oxic-anoxic interface is subject to change due to fluctuating water table levels. Other important processes and factors affecting metal mobility in floodplain soils are adsorption/desorption processes, salinity, the presence of organic matter, sulphur and carbonates, pH and plant growth. Many authors report highly significant correlations between cation exchange capacity, clay or organic matter contents and metal contents in floodplain soils. Iron and manganese (hydr)oxides were found to be the main carriers for Cd, Zn and Ni under oxic conditions, whereas the organic fraction was most important for Cu. The mobility and availability of metals in a floodplain soil can be significantly reduced by the formation of metal sulphide precipitates under anoxic conditions. Ascending salinity in the flood water promotes metal desorption from the floodplain soil in the absence of sulphides, hence increases total metal concentrations in the water column. The net effect of the presence of organic matter can either be a decrease or an increase in metal mobility, whereas the presence of carbonates in calcareous floodplain soils or sediments constitutes an effective buffer against a pH decrease. Moreover, carbonates may also directly precipitate metals. Plants can affect the metal mobility in floodplain soils by oxidising their rhizosphere, taking up metals, excreting exudates and stimulating the activity of

  18. Use of porewater extracts to identify the cause of toxicity in marine and estuarine sediments

    SciTech Connect

    Douglas, W.S.

    1994-12-31

    Amphipod toxicity tests in the evaluation of dredged material proposed for ocean disposal has come under increased scrutiny by the regulated community in the Port of NY/NJ. In recent large-scale assessments of sediment quality in the harbor, the vast majority of locations were deemed highly contaminated when tested with Ampelisca abdita. Toxicity tests, by themselves, do not provide data regarding the cause of toxicity of these sediments. The enormous potential costs associated with most proposed alternatives to ocean disposal of dredged sediments has prompted the investigation of the causative agents of toxicity in sediments of the NY/NJ Harbor. Sediment from five locations in the harbor, selected in consultation with local regulatory agencies to represent diverse potential contamination scenarios, was collected and tested for toxicity to the amphipods Ampelisca abdita, Leptocheirus plumulosus, Eohaustorius estuadus, Rhepoxynius abronius, and the mysid shrimp, Mysidopsis bahia, using 10-day static bioassays. Porewater from each of the five sediments was extracted under centrifugation and used in water-only toxicity tests with A. abdita, L. plumulosus, R. abronius, E. estuadus, M. bahia, M. beryllina, and Microtox. A Phase 1 Toxicity Identification Evaluation of the three most toxic porewater samples was conducted using several of the species tested. Results from the preliminary investigations and the ongoing TIE`s will be presented. Species selection, porewater toxicity test procedures, and Phase 1, 2, and 3 paradigms will be discussed.

  19. Method for assessing the chronic toxicity of marine and estuarine sediment-associated contaminants using the amphipod Corophium volutator.

    PubMed

    Scarlett, A; Rowland, S J; Canty, M; Smith, E L; Galloway, T S

    2007-06-01

    Acute sediment toxicity tests do not test key life stage events such as moulting and reproduction and therefore do not reveal the longer-term effects of contaminant exposure. A laboratory method is described for determining the chronic toxicity of contaminants associated with whole sediments. The test is conducted using neonates of the estuarine amphipod Corophium volutator at 15 degrees C, salinity 25 psu and a 12 h light:12 h dark photoperiod. The endpoints are survival and growth after 28 days and survival, growth and reproduction of amphipods upon termination of test i.e. reproduction within all control vessels (ca 75 days). The sediment chronic toxicity test was used to investigate the effects of sediments spiked with environmentally relevant preparations of slightly weathered Alaskan North Slope crude oil, including a water-accommodated-fraction (WAF) and a chemically-dispersed (Corexit 9527) WAF. Sediment oil concentrations were quantified using ultra-violet fluorescence. The amphipods exposed to chemically dispersed oil had higher mortality and lower growth rates than control-, Corexit 9527- and WAF-exposed organisms, resulting in reduced reproduction. The described method supplements the standard acute sediment test and would be particularly useful when long-term ecological effects are suspected but acute tests reveal no significant mortality. The sediment chronic test reported herein has shown that sediment that was not evidently toxic during 10-day acute tests could have population-level effects on sediment-dwelling amphipods.

  20. Multi-element study of sediments from the river Khai River - Nha Trang Bay estuarine system, South China Sea.

    NASA Astrophysics Data System (ADS)

    Koukina, Sofia; Lobus, Nikolai; Peresypkin, Valery; Baturin, Gleb; Smurov, Andrey

    2013-04-01

    Major (Al, Fe, Ti, Mg, Ca, Na, K), minor (Mn) and trace (Cr, Ni, Cd, V, Zn, Cu, Pb, Sb, Bi, Sn, Ag, Li, Co, As, Zr, Mo, Hg) elements along with nutrients (TOC, TS, TP) and TIC were first determined in ten surface sediment samples from the Khai River - Nha Trang Bay estuarine system, South China Sea. According to the sediment quality guidelines and reference background values, most of the element contents that were studied were below the threshold levels, while the content of Ag exceeded significantly the hazardous levels in the most of the samples along the river - sea transect. The local anthropogenic and/or environmental sources of Ag within the region need special study. Aluminum and lithium normalization indicated some specific features in the abundance and distribution of the elements along the salinity gradient. The mean grain size of the sediments decreased from the river part to the bay part of the transect. Sedimentary TOC was relatively low (1-2 %) and showed independent distribution along the river - sea transect in relation to the other elements that were studied. Ca, Ba and Sr distribution showed some sporadic enrichment and were largely controlled by the TIC content in sediments. Sedimentary TP, Al, Fe, Mn, Ti, Na, K, Li, Co, Cs, Zn and V varied within the narrow range and tended to increase seaward. These elements are most likely controlled by the accumulation of their fine grained aluminosilicate host minerals and materials at sites determined by hydrodynamic conditions, i. e., in the sea floor depression. TS, As, Sn, Bi, U, Cd and Mo were relatively low in the sediments studied and tended to decrease seaward with the slight elevation in the intermediate part of the transect. These elements can be scavenged by and/or co-precipitated with the dissolved and particulate materials of the river discharge and further deposited on the river - sea geochemical barrier in the course of estuarine sedimentation. The distribution of Ni, Cr, Zr Cu, Pb, Sb, Hg and

  1. Nanosilver inhibits nitrification and reduces ammonia-oxidising bacterial but not archaeal amoA gene abundance in estuarine sediments.

    PubMed

    Beddow, Jessica; Stolpe, Björn; Cole, Paula A; Lead, Jamie R; Sapp, Melanie; Lyons, Brett P; Colbeck, Ian; Whitby, Corinne

    2017-02-01

    Silver nanoparticles (AgNPs) enter estuaries via wastewater treatment effluents, where they can inhibit microorganisms, because of their antimicrobial properties. Ammonia-oxidising bacteria (AOB) and archaea (AOA) are involved in the first step of nitrification and are important to ecosystem function, especially where effluent discharge results in high nitrogen inputs. Here, we investigated the effect of a pulse addition of AgNPs on AOB and AOA ammonia monooxygenase (amoA) gene abundances and benthic nitrification potential rates (NPR) in low-salinity and mesohaline estuarine sediments. Whilst exposure to 0.5 mg L(-1) AgNPs had no significant effect on amoA gene abundances or NPR, 50 mg L(-1) AgNPs significantly decreased AOB amoA gene abundance (up to 76% over 14 days), and significantly decreased NPR by 20-fold in low-salinity sediments and by twofold in mesohaline sediments, after one day. AgNP behaviour differed between sites, whereby greater aggregation occurred in mesohaline waters (possibly due to higher salinity), which may have reduced toxicity. In conclusion, AgNPs have the potential to reduce ammonia oxidation in estuarine sediments, particularly where AgNPs accumulate over time and reach high concentrations. This could lead to long-term risks to nitrification, especially in polyhaline estuaries where ammonia-oxidation is largely driven by AOB. © 2016 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

  2. A field test and comparison of acute and chronic sediment toxicity tests with the estuarine amphipod Leptocheirus plumulosus in Chesapeake Bay, USA.

    PubMed

    McGee, Beth L; Fisher, Daniel J; Wright, David A; Yonkos, Lance T; Ziegler, Gregory P; Turley, Steven D; Farrar, J Daniel; Moore, David W; Bridges, Todd S

    2004-07-01

    A 28-d partial life-cycle test with the estuarine amphipod Leptocheirus plumulosus was developed in response to the need for an assay to mimic chronic exposure to sediment-associated contaminants. To ensure that toxicity tests have environmental relevance, it is essential to evaluate the relationship between laboratory responses and field measures of contamination. Consequently, one objective of the study was to compare the results of the chronic sediment toxicity test with L. plumulosus to gradients of sediment contamination and the in situ benthic community in its native Chesapeake Bay. Chronic tests were conducted by two laboratories, the Army Corps of Engineers Waterways Experiment Station ([WES]; Vicksburg, MS, USA) and the University of Maryland ([UM] College Park, MD, USA) using different feeding regimes, providing the opportunity to evaluate the effect of this variable on response sensitivity. A second objective was to compare the relative sensitivity of acute and chronic tests with L. plumulosus with field-collected sediments. Overall, there was good agreement between the toxicological response of acute and chronic tests with L. plumulosus and field measures of contamination. Survival in the acute test and chronic test conducted by WES was negatively correlated with concentrations of sediment-associated contaminants. Survival in acute exposures was significantly reduced in sediments from 8 of 11 stations. Indigenous L. plumulosus were found only at two of the three stations that did not exhibit acute toxicity. An unexpected finding was the difference in responsiveness of the two chronic tests. Survival in tests conducted by UM and WES was significantly reduced in sediments from 4 and 6 of 11 stations, respectively. No additional sublethal toxicity was detected in the UM chronic test, but the WES test detected reproductive effects at two additional stations. We believe the observed differences were related to the test diet used. Partly as a result of our

  3. Assessment of sediment contamination, acute toxicity, and population viability of the estuarine amphipod Leptocheirus plumulosus in Baltimore Harbor, Maryland, USA

    SciTech Connect

    McGee, B.L.; Fisher, D.J.; Yonkos, L.T.; Ziegler, G.P.; Turley, S.

    1999-10-01

    In Chesapeake Bay, Maryland, USA, some of the most contaminated sediments are found in the highly industrialized Baltimore Harbor-Patapsco River area. As part of a comprehensive assessment of sediment quality in this system, sediment toxicity was assessed in 10-d acute tests with the estuarine amphipod Leptocheirus plumulosus. Mean amphipod survival was significantly reduced in 7 of the 25 samples tested despite the occurrence of minor experimental artifacts. The most toxic sediments were collected from Bear Creek; other areas exhibiting toxicity included the Inner Harbor and Colgate Creek. Marginal toxicity was observed in samples from Curtis Creek, Lazeretto Point, and Back River. Negative relationships were detected between survival and concentrations of select sediment-associated contaminants, whereas a very strong positive association existed between survival in laboratory exposures and density of L. plumulosus at the test sites. A weight of evidence approach, including correlation analyses, a model of polycyclic aromatic hydrocarbon bioavailability, and comparisons to benchmark sediment levels, was used to tentatively identify classes of contaminants that contributed to the observed toxicity. Analysis of results suggested that toxicity at stations in Bear Creek and Colgate Creek may have been driven by sediment-associated metals, whereas toxicity at stations in the Inner Harbor was likely due to both metal and organic contaminants. The observed relationships among toxicity test results, concentrations of sediment-associated contaminants, and abundance of L. plumulosus at the test sites suggests that acute toxicity tests with this species are indicative of adverse biological effects in the field.

  4. Spatial distribution of phosphorus speciation in marsh sediments along a hydrologic gradient in a subtropical estuarine wetland, China

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-Long; Zeng, Cong-Sheng; Tong, Chuan; Zhai, Shui-Jing; Lin, Xiao; Gao, Deng-Zhou

    2015-03-01

    In May and August 2013, a 360-m long transect (from a high to a middle tidal flat) was laid out in the Min River estuarine marsh to study the distribution of total phosphorus (TP) and its fractions (i.e., organic P (Org P), inorganic P (IP), aluminum-bound P (Al-P), iron-bound P (Fe-P), occluded P (O-P), and calcium-bound P (Ca-P)). The results showed that TP concentrations of the sediments ranged from 338 to 846 mg kg-1 (average 664 mg kg-1) in May and from 353 to 932 mg kg-1 (average 657 mg kg-1) in August. IP dominated the P fractions (accounting for 57-81% of TP) and was mainly composed of Fe-P (38%), O-P (30%), and Ca-P (25%). The TP, IP and Fe-P concentrations fluctuated along the hydrologic gradient during both measurement periods (except for the upper 10-cm sediments in August). Meanwhile, their concentrations decreased with depth (0-50 cm), but vertical variation declined in the middle tidal flat. A higher concentration of Org P was observed in the upper 20-cm sediments of the high tidal flat. The concentrations of Ca-P and Al-P increased from the high tidal flat to the middle tidal flat, but there was no significant difference between sediment layers (P > 0.05). The O-P concentration was significantly higher in Phragmites australis sediments compared with Cyperus malaccensis sediments (P < 0.05). Based on the space-for-time substitution rule, we predict that sea-level change will likely alter the composition and vertical distribution of TP in the Min River estuarine sediments.

  5. Tropical Estuarine Macrobenthic Communities Are Structured by Turnover Rather than Nestedness

    PubMed Central

    Medeiros, Carlinda Raílly; Hepp, Luiz Ubiratan; Patrício, Joana; Molozzi, Joseline

    2016-01-01

    Turnover (i.e., species substitution) and nestedness (i.e., subsets of species from more diverse locations), the two main mechanisms used to explain the beta diversity of biological communities, have different implications for biodiversity conservation. To better understand how these mechanisms contribute to beta diversity, we tested the following hypotheses: (i) greater dissimilarity in community composition occurs between estuarine zones than other hierarchical level studied; (ii) beta diversity in these communities develops by turnover in estuaries with a lower degree of anthropogenic impact, but by nestedness in estuaries with a greater degree of anthropogenic impact; and (iii) the structuring mechanism is independent of season. We studied two tropical estuaries (dry and wet seasons) that vary in terms of land-use of the drainage basins. Subtidal benthic macroinvertebrates were sampled along the estuarine gradient in each of the two estuaries. The additive partitioning approach to species diversity was used to determine the hierarchical scale with the greatest dissimilarity in community composition. General beta diversity was measured using the Sorensen dissimilarity index, partitioning the turnover and nestedness components. The greatest dissimilarity in the composition of the communities occurred between the zones along the estuarine gradient in both seasons (dry = 58.6%; wet = 46.3%). In the estuary with a lower degree of anthropogenic influence, benthic macroinvertebrate diversity was generated by turnover regardless of the season. In the estuary with a greater degree of anthropogenic impact, beta diversity was structured by turnover during the dry season and a combination of both mechanisms during the wet season. We conclude that turnover is the principal mechanism responsible for beta diversity in benthic macroinvertebrate communities in tropical estuaries. PMID:27584726

  6. Tropical Estuarine Macrobenthic Communities Are Structured by Turnover Rather than Nestedness.

    PubMed

    Medeiros, Carlinda Raílly; Hepp, Luiz Ubiratan; Patrício, Joana; Molozzi, Joseline

    2016-01-01

    Turnover (i.e., species substitution) and nestedness (i.e., subsets of species from more diverse locations), the two main mechanisms used to explain the beta diversity of biological communities, have different implications for biodiversity conservation. To better understand how these mechanisms contribute to beta diversity, we tested the following hypotheses: (i) greater dissimilarity in community composition occurs between estuarine zones than other hierarchical level studied; (ii) beta diversity in these communities develops by turnover in estuaries with a lower degree of anthropogenic impact, but by nestedness in estuaries with a greater degree of anthropogenic impact; and (iii) the structuring mechanism is independent of season. We studied two tropical estuaries (dry and wet seasons) that vary in terms of land-use of the drainage basins. Subtidal benthic macroinvertebrates were sampled along the estuarine gradient in each of the two estuaries. The additive partitioning approach to species diversity was used to determine the hierarchical scale with the greatest dissimilarity in community composition. General beta diversity was measured using the Sorensen dissimilarity index, partitioning the turnover and nestedness components. The greatest dissimilarity in the composition of the communities occurred between the zones along the estuarine gradient in both seasons (dry = 58.6%; wet = 46.3%). In the estuary with a lower degree of anthropogenic influence, benthic macroinvertebrate diversity was generated by turnover regardless of the season. In the estuary with a greater degree of anthropogenic impact, beta diversity was structured by turnover during the dry season and a combination of both mechanisms during the wet season. We conclude that turnover is the principal mechanism responsible for beta diversity in benthic macroinvertebrate communities in tropical estuaries.

  7. Assessing environmental drivers of microbial communities in estuarine soils of the Aconcagua River in Central Chile.

    PubMed

    Fuentes, Sebastián; Ding, Guo-Chun; Cárdenas, Franco; Smalla, Kornelia; Seeger, Michael

    2015-10-01

    Aconcagua River basin (Central Chile) harbors diverse economic activities such as agriculture, mining and a crude oil refinery. The aim of this study was to assess environmental drivers of microbial communities in Aconcagua River estuarine soils, which may be influenced by anthropogenic activities taking place upstream and by natural processes such as tides and flood runoffs. Physicochemical parameters were measured in floodplain soils along the estuary. Bacteria, Actinobacteria, Alphaproteobacteria, Betaproteobacteria, Pseudomonas, Bacillus and Fungi were studied by DGGE fingerprinting of 16S rRNA gene and ribosomal ITS-1 amplified from community DNA. Correlations between environment and communities were assessed by distance-based redundancy analysis. Mainly hydrocarbons, pH and the composed variable copper/arsenic/calcium but in less extent nitrogen and organic matter/phosphorous/magnesium correlated with community structures at different taxonomic levels. Aromatic hydrocarbons degradation potential by bacterial community was studied. Polycyclic aromatic hydrocarbon ring-hydroxylating dioxygenases genes were detected only at upstream sites. Naphthalene dioxygenase ndo genes were heterogeneously distributed along estuary, and related to Pseudomonas, Delftia, Comamonas and Ralstonia. IncP-1 plasmids were mainly present at downstream sites, whereas IncP-7 and IncP-9 plasmids showed a heterogeneous distribution. This study strongly suggests that pH, copper, arsenic and hydrocarbons are main drivers of microbial communities in Aconcagua River estuarine soils.

  8. Anthropogenic Influences on Estuarine Sedimentation and Ecology: Examples from Varved Sediments of the Pettaquamscutt River Estuary, Rhode Island

    EPA Science Inventory

    Estuaries and lakes are undergoing anthropogenic alterations as development and industry intensify in the modern world. Assessing the ecological health of such water bodies is difficult because accurate accounts of pre-anthropogenic estuarine/lacustrine conditions do not exist. ...

  9. Anthropogenic Influences on Estuarine Sedimentation and Ecology: Examples from Varved Sediments of the Pettaquamscutt River Estuary, Rhode Island

    EPA Science Inventory

    Estuaries and lakes are undergoing anthropogenic alterations as development and industry intensify in the modern world. Assessing the ecological health of such water bodies is difficult because accurate accounts of pre-anthropogenic estuarine/lacustrine conditions do not exist. ...

  10. Mangrovimonas xylaniphaga sp. nov. isolated from estuarine mangrove sediment of Matang Mangrove Forest, Malaysia.

    PubMed

    Dinesh, Balachandra; Furusawa, Go; Amirul, A A

    2017-01-01

    A Gram-staining-negative, aerobic, rod-shaped, yellow-orange-pigmented, gliding bacterium, designated as strain ST2L12(T), was isolated from estuarine mangrove sediment from Matang Mangrove Forest, Perak, Malaysia. Strain ST2L12(T) grew at 15-39 °C, pH 6-8 and in 1-6 % (w/v) NaCl. This strain was able to degrade xylan and casein. 16S rRNA gene sequence analysis showed 95.3-92.8 % similarity to members of the genera Mangrovimonas, Meridianimaribacter, Sediminibacter, Gaetbulibacter and Hoppeia. Phylogenetic analysis indicated that it belonged to the family Flavobacteriaceae. Respiratory quinone present was menaquinone-6 (MK-6), and the DNA G+C content was 38.3 mol%. The predominant fatty acids were iso-C15:0, iso-C15:1, C15:0 and iso-C17:0 3-OH. Moreover, previous genome comparison study showed that the genome of ST2L12(T) is 1.4 times larger compared to its closest relative, Mangrovimonas yunxiaonensis LYYY01(T). Phenotypic, fatty acid, 16S rRNA gene sequence and previous genome data indicate that strain ST2L12(T) represents a novel species of the genus Mangrovimonas in the family Flavobacteriaceae, for which the name Mangrovimonas xylaniphaga sp. nov. is proposed. The type strain of Mangrovimonas xylaniphaga is ST2L12(T) (=LMG 28914(T)=JCM 30880(T)).

  11. Multiproxy evidence of Holocene climate variability from estuarine sediments, eastern North America

    USGS Publications Warehouse

    Cronin, T. M.; Thunell, R.; Dwyer, G.S.; Saenger, C.; Mann, M.E.; Vann, C.; Seal, R.R.

    2005-01-01

    We reconstructed paleoclimate patterns from oxygen and carbon isotope records from the fossil estuarine benthic foraminifera Elphidium and Mg/ Ca ratios from the ostracode Loxoconcha from sediment cores from Chesapeake Bay to examine the Holocene evolution of North Atlantic Oscillation (NAO)-type climate variability. Precipitation-driven river discharge and regional temperature variability are the primary influences on Chesapeake Bay salinity and water temperature, respectively. We first calibrated modern ??18 Owater to salinity and applied this relationship to calculate trends in paleosalinity from the ??18 Oforam, correcting for changes in water temperature estimated from ostracode Mg /Ca ratios. The results indicate a much drier early Holocene in which mean paleosalinity was ???28 ppt in the northern bay, falling ???25% to ???20 ppt during the late Holocene. Early Holocene Mg/Ca-derived temperatures varied in a relatively narrow range of 13?? to 16??C with a mean temperature of 14.2??C and excursions above 16??C; the late Holocene was on average cooler (mean temperature of 12.8??C). In addition to the large contrast between early and late Holocene regional climate conditions, multidecadal (20-40 years) salinity and temperature variability is an inherent part of the region's climate during both the early and late Holocene, including the Medieval Warm Period and Little Ice Age. These patterns are similar to those observed during the twentieth century caused by NAO-related processes. Comparison of the midlatitude Chesapeake Bay salinity record with tropical climate records of Intertropical Convergence Zone fluctuations inferred from the Cariaco Basin titanium record suggests an anticorrelation between precipitation in the two regions at both millennial and centennial timescales. Copyright 2005 by the American Geophysical Union.

  12. Metal enrichment in estuarine sediments proximal to acid sulfate soils as a novel palaeodrought proxy.

    PubMed

    Job, Thomas; Penny, Dan; Hua, Quan

    2017-08-26

    Persistent drought over eastern Australia at the turn of the last millennium reduced stream flow in Australia's largest and most economically important drainage basin. Low water levels in the basin's terminal lakes triggered widespread pyrite oxidation, which altered surface water chemistry and released metals into the environment. The frequency of these events, and the links between drought and acid sulfate soil activation, are not known because the historical and instrumental records are short. Here, we present a Holocene-aged record of trace metal enrichment from Lake Albert-part of the terminal Lower Lakes system of the Murray-Darling Basin, Australia-that demonstrates the potential of trace elements mobilised during acidification events for palaeodrought reconstructions. Symptomatic metals were measured from a core of clayey sediment to form a multi-element assemblage that reveals acidification events in the geological past. Correlation with regional climate proxies suggests that climate forcing is significant in driving metal flux to estuarine sinks in acid sulfate soil rich landscapes, although the intensity of a drought is not the only variable responsible for acidification intensity. The constructed record indicates that regional climate moved from a generally humid climate phase with intermittent droughts, to a more arid climate at ~5.2ka which prevailed until ~1.7ka. Following conditions were relatively wet with low climatic variability through till European Settlement. Enrichment is observed coincident with both the 1982-83 drought and Millennium Drought, the latter of which reaching an intensity unsurpassed in the last ~4.8ka, likely a product of anthropogenic changes to the Lower Murray-Darling Basin system. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Isotopic distribution of carbon from sewage sludge and eutrophication in the sediments and food web of estuarine ecosystems

    SciTech Connect

    Gearing, P.J.; Gearing, J.N.; Maughan, J.T.; Oviatt, C.A. )

    1991-02-01

    Stable isotope ratios ({delta}{sup 13}C) from samples of water, sediments, and biota traced the behavior of organic carbon for 3 summer months in estuarine mesocosms (three controls, three with added sewage sludge, three with added inorganic nutrients). Isotope ratios proved to be a useful quantitative tracer for sewage carbon as well as for the fresh phytoplanktonic carbon produced during nutrient fertilization. Sewage sludge sedimented within hours of its addition, and approximately 50% remained in sediments after 99 days. The sludge was not inert, but was biologically oxidized at rates similar to those of phytoplankton carbon. Its residence time in the water column was too short for uptake by zooplankton, but it was readily assimilated by some benthic organisms. Fresh phytoplanktonic carbon from nutrient-induced blooms was isotopically heavy and thus distinguishable from old primary production (fixed before the experiment). It flowed through the pelagic and benthic food webs more extensively and more uniformly than did sludge carbon.

  14. RESPONSE OF GHOST SHRIMP (NEOTRYPAEA CALIFORNIENSIS) BIOTURBATION TO ORGANIC MATTER ENRICHMENT OF ESTUARINE INTERTIDAL SEDIMENTS

    EPA Science Inventory

    Populations of burrowing shrimp (Neotrypaea californiensis and Upogebia p;ugettensis) are the dominant invertebrate fauna on Pacific estuarine tide flats, occupying >80% of intertidal area in some estuaries. Burrowing shrimp are renowned for their bioturbation of intertidal sedi...

  15. RESPONSE OF GHOST SHRIMP (NEOTRYPAEA CALIFORNIENSIS) BIOTURBATION TO ORGANIC MATTER ENRICHMENT OF ESTUARINE INTERTIDAL SEDIMENTS

    EPA Science Inventory

    Populations of burrowing shrimp (Neotrypaea californiensis and Upogebia p;ugettensis) are the dominant invertebrate fauna on Pacific estuarine tide flats, occupying >80% of intertidal area in some estuaries. Burrowing shrimp are renowned for their bioturbation of intertidal sedi...

  16. The role of salinity in shaping dissolved inorganic nitrogen and N₂O dynamics in estuarine sediment-water interface.

    PubMed

    Teixeira, Catarina; Magalhães, Catarina; Joye, Samantha B; Bordalo, Adriano A

    2013-01-15

    We investigated the influence of salinity on sediment inorganic nitrogen dynamics in three Portuguese estuaries (Cávado, Ave and Douro). Anaerobic slurry experiments were run at different salinity treatments (0, 10, and 25) and net changes in concentration of nitrate, nitrite, ammonium, and nitrous oxide were monitored. Salinity-induced NH₄⁺ sediment desorption was observed at all sites. No significant salinity driven changes in NO₃⁻ concentrations were observed, except for Ave estuarine sediments, where NO₃⁻ consumption increased 10 times as the salinity rose from 0 to 10. In the upper stretches of the three estuaries, N₂O production increased sharply as salinity rose. Although no stimulation of N₂O production was observed in higher salinity areas, the salinity-driven changes in N₂O production are of major concern given the greenhouse characteristics of the gas. The global trend of decreasing freshwater discharge, and therefore increase in salinity, to estuarine systems could thereby exacerbate N₂O production and global warming. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Estuarine bed-sediment-quality data collected in New Jersey and New York after Hurricane Sandy, 2013

    USGS Publications Warehouse

    Fischer, Jeffrey M.; Phillips, Patrick J.; Reilly, Timothy J.; Focazio, Michael J.; Loftin, Keith A.; Benzel, William M.; Jones, Daniel K.; Smalling, Kelly L.; Fisher, Shawn C.; Fisher, Irene J.; Iwanowicz, Luke R.; Romanok, Kristin M.; Jenkins, Darkus E.; Bowers, Luke; Boehlke, Adam; Foreman, William T.; Deetz, Anna C.; Carper, Lisa G.; Imbrigiotta, Thomas E.; Birdwell, Justin E.

    2015-01-01

    Bed-sediment samples were collected from June to October 2013 from 167 estuarine sites extending from Cape May, New Jersey, to the New York Harbor and the eastern end of Long Island. Each sampling location and study region was characterized by using geographic information to identify potential contaminant sources. Characterizations included land cover, locations and types of businesses (industrial, financial, and others), spills (sewage, chemical, and others), bulk storage facilities, effluent discharges within 2 kilometers of the sampling point, and discharges within inundated and non-inundated regions near the sampling location. Samples were analyzed for particle size, total organic carbon, metals and trace elements, semivolatile organic compounds, wastewater compounds, hormones, and sediment toxicity. Samples were also screened using x-ray fluorescence, Fourier transform infrared spectroscopy, and x-ray diffraction. In addition, bioassays for endocrine disruptors and protein phosphatase 2A inhibition were conducted. The study was designed to provide the data needed to understand the extent and sources of contamination resulting from Hurricane Sandy, to compare the chemistry and toxicity of estuarine bed sediments before and after the storm, and to evaluate the usefulness of rapid screening and bioassay approaches in disaster settings.

  18. Vertical geochemical distribution of some contaminants in estuarine sediments from the Jaboatão River, Pernambuco, Northeastern Brazil.

    NASA Astrophysics Data System (ADS)

    Lima, Marta; Neumann, Virgínio; Castro, Maria Teresa; Lima, Enjôlras; Lima, Edmilson; Silva, Ricardo

    2014-05-01

    Sediment core samples with length ranging from 50 cm was collected in the Jaboatão river estuary and analyzed to ( As, Cr, Pb, Hg, Ni and Zn) level concentrations using instrumental neutron activation analysis (INAA). The studied area is located in the northeastern coast of Pernambuco State and is comprised of a densely urbanized region, the largest industrial complex of the state, with a predominance of fertilizer plants. These elements have a consistent vertical evolution compatible with the increase of the pelitic-organic material. There is an increase from bottom to top of the core but this may not represent a real increase in the input, but rather a concentration associated to the fine particle fraction and organic matter that increases to the top of the core profile. These conditions of clay predominance in estuarine sediments on the top indicate a decrease of the energy condition in the system and not necessarily an increase in the supply of contaminating metals. The majority of the chemical species, the concentration did not reach toxicity levels, when considering the values (ERL and ERM) established by USEPA (1998). The only exception is Cr, which has already surpassed the ERM value, and suggests that this increase is related to industrial contribution. Chromium concentration reached preliminary alert levels according to international environmental agencies, whereas the other species analyzed do not show toxicity. Key-words: environmental geochemistry, estuarine sediments

  19. Long-term (two annual cycles) phytoremediation of heavy metal-contaminated estuarine sediments by Phragmites australis.

    PubMed

    Cicero-Fernández, Diego; Peña-Fernández, Manuel; Expósito-Camargo, Jose A; Antizar-Ladislao, Blanca

    2017-09-25

    The long-term (i.e., two consecutive annual cycles) ability of Phragmites australis to remediate estuarine sediments contaminated with heavy metals (Co, Ni, Mo, Cd, Pb, Cr, Cu, Fe, Mn, Zn and Hg) and trace elements of concern (As, Se, Ba) was investigated using an experimental approach on a pilot plant scale. The accumulation of these elements on belowground and aboveground tissues was monitored during vegetative and senescence periods for two populations of P. australis, originally from contaminated (MIC) and non-contaminated (GAL) estuaries, respectively. The initial concentration of the elements in the contaminated estuarine sediment decreased in the following order: Fe>Mn>Zn>Pb>Ba>Cr>As>Cu>Ni>Co>Mo>Cd>Se>Hg. A similar trend was recorded in the belowground biomass following remediation, suggesting the potential role of P. australis as an effective biomonitoring tool. Hg was not detected in any plant tissue. An overall annual increase of concentration levels in belowground tissue was observed. Overall, this study suggested that P. australis populations from GAL were substantially more efficient in taking up Ni, Mo and Cr during the second annual cycle in both belowground and aboveground tissue than P. australis populations from MIC. Calculated bio-concentration factors (BCF) suggested a clear metal excluder strategy for Co, Cd, Pb, Cu and Fe, with accumulation and stabilisation belowground, with limited translocation into aerial tissues observed during the length of this study. An excluder behaviour for Zn, Ba and Mn was detected during the second annual cycle, coinciding with a substantial increase of concentration levels belowground. This study demonstrated for the first time the long term efficacy of P. australis for phytoremediation of heavy metal contaminated estuarine sediments. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Sudden Clearing of Estuarine Waters upon Crossing the Threshold from Transport to Supply Regulation of Sediment Transport as an Erodible Sediment Pool is Depleted: San Francisco Bay, 1999

    USGS Publications Warehouse

    Schoellhamer, D.H.

    2011-01-01

    The quantity of suspended sediment in an estuary is regulated either by transport, where energy or time needed to suspend sediment is limiting, or by supply, where the quantity of erodible sediment is limiting. This paper presents a hypothesis that suspended-sediment concentration (SSC) in estuaries can suddenly decrease when the threshold from transport to supply regulation is crossed as an erodible sediment pool is depleted. This study was motivated by a statistically significant 36% step decrease in SSC in San Francisco Bay from water years 1991-1998 to 1999-2007. A quantitative conceptual model of an estuary with an erodible sediment pool and transport or supply regulation of sediment transport is developed. Model results confirm that, if the regulation threshold was crossed in 1999, SSC would decrease rapidly after water year 1999 as observed. Estuaries with a similar history of a depositional sediment pulse followed by erosion may experience sudden clearing. ?? 2011 Coastal and Estuarine Research Federation (outside the USA).

  1. Diversity and abundance of nitrate reductase genes (narG and napA), nitrite reductase genes (nirS and nrfA), and their transcripts in estuarine sediments.

    PubMed

    Smith, Cindy J; Nedwell, David B; Dong, Liang F; Osborn, A Mark

    2007-06-01

    Estuarine systems are the major conduits for the transfer of nitrate from agricultural and other terrestrial-anthropogenic sources into marine ecosystems. Within estuarine sediments some microbially driven processes (denitrification and anammox) result in the net removal of nitrogen from the environment, while others (dissimilatory nitrate reduction to ammonium) do not. In this study, molecular approaches have been used to investigate the diversity, abundance, and activity of the nitrate-reducing communities in sediments from the hypernutrified Colne estuary, United Kingdom, via analysis of nitrate and nitrite reductase genes and transcripts. Sequence analysis of cloned PCR-amplified narG, napA, and nrfA gene sequences showed the indigenous nitrate-reducing communities to be both phylogenetically diverse and also divergent from previously characterized nitrate reduction sequences in soils and offshore marine sediments and from cultured nitrate reducers. In both the narG and nrfA libraries, the majority of clones (48% and 50%, respectively) were related to corresponding sequences from delta-proteobacteria. A suite of quantitative PCR primers and TaqMan probes was then developed to quantify phylotype-specific nitrate (narG and napA) and nitrite reductase (nirS and nrfA) gene and transcript numbers in sediments from three sites along the estuarine nitrate gradient. In general, both nitrate and nitrite reductase gene copy numbers were found to decline significantly (P < 0.05) from the estuary head towards the estuary mouth. The development and application, for the first time, of quantitative reverse transcription-PCR assays to quantify mRNA sequences in sediments revealed that transcript numbers for three of the five phylotypes quantified were greatest at the estuary head.

  2. New climatic targets against global warming: will the maximum 2 °C temperature rise affect estuarine benthic communities?

    PubMed

    Crespo, Daniel; Grilo, Tiago Fernandes; Baptista, Joana; Coelho, João Pedro; Lillebø, Ana Isabel; Cássio, Fernanda; Fernandes, Isabel; Pascoal, Cláudia; Pardal, Miguel Ângelo; Dolbeth, Marina

    2017-06-20

    The Paris Agreement signed by 195 countries in 2015 sets out a global action plan to avoid dangerous climate change by limiting global warming to remain below 2 °C. Under that premise, in situ experiments were run to test the effects of 2 °C temperature increase on the benthic communities in a seagrass bed and adjacent bare sediment, from a temperate European estuary. Temperature was artificially increased in situ and diversity and ecosystem functioning components measured after 10 and 30 days. Despite some warmness effects on the analysed components, significant impacts were not verified on macro and microfauna structure, bioturbation or in the fluxes of nutrients. The effect of site/habitat seemed more important than the effects of the warmness, with the seagrass habitat providing more homogenous results and being less impacted by warmness than the adjacent bare sediment. The results reinforce that most ecological responses to global changes are context dependent and that ecosystem stability depends not only on biological diversity but also on the availability of different habitats and niches, highlighting the role of coastal wetlands. In the context of the Paris Agreement it seems that estuarine benthic ecosystems will be able to cope if global warming remains below 2 °C.

  3. Measuring hypoxia induced metal release from highly contaminated estuarine sediments during a 40 day laboratory incubation experiment.

    PubMed

    Banks, Joanne L; Ross, D Jeff; Keough, Michael J; Eyre, Bradley D; Macleod, Catriona K

    2012-03-15

    Nutrient inputs to estuarine and coastal waters worldwide are increasing and this in turn is increasing the prevalence of eutrophication and hypoxic and anoxic episodes in these systems. Many urbanised estuaries are also subject to high levels of anthropogenic metal contamination. Environmental O(2) levels may influence whether sediments act as sinks or sources of metals. In this study we investigated the effect of an extended O(2) depletion event (40 days) on fluxes of trace metals (and the metalloid As) across the sediment-water interface in sediments from a highly metal contaminated estuary in S.E. Tasmania, Australia. We collected sediments from three sites that spanned a range of contamination and measured total metal concentration in the overlying water using sealed core incubations. Manganese and iron, which are known to regulate the release of other divalent cations from sub-oxic sediments, were released from sediments at all sites as hypoxia developed. In contrast, the release of arsenic, cadmium, copper and zinc was comparatively low, most likely due to inherent stability of these elements within the sediments, perhaps as a result of their refractory origin, their association with fine-grained sediments or their being bound in stable sulphide complexes. Metal release was not sustained due to the powerful effect of metal-sulphide precipitation of dissolved metals back into sediments. The limited mobilisation of sediment bound metals during hypoxia is encouraging, nevertheless the results highlight particular problems for management in areas where hypoxia might occur, such as the release of metals exacerbating already high loads or resulting in localised toxicity. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Non-native ecosystem engineer alters estuarine communities.

    PubMed

    Heiman, Kimberly W; Micheli, Fiorenza

    2010-08-01

    Many ecosystems are created by the presence of ecosystem engineers that play an important role in determining species' abundance and species composition. Additionally, a mosaic environment of engineered and non-engineered habitats has been shown to increase biodiversity. Non-native ecosystem engineers can be introduced into environments that do not contain or have lost species that form biogenic habitat, resulting in dramatic impacts upon native communities. Yet, little is known about how non-native ecosystem engineers interact with natives and other non-natives already present in the environment, specifically whether non-native ecosystem engineers facilitate other non-natives, and whether they increase habitat heterogeneity and alter the diversity, abundance, and distribution of benthic species. Through sampling and experimental removal of reefs, we examine the effects of a non-native reef-building tubeworm, Ficopomatus enigmaticus, on community composition in the central Californian estuary, Elkhorn Slough. Tubeworm reefs host significantly greater abundances of many non-native polychaetes and amphipods, particularly the amphipods Monocorophium insidiosum and Melita nitida, compared to nearby mudflats. Infaunal assemblages under F. enigmaticus reefs and around reef's edges show very low abundance and taxonomic diversity. Once reefs are removed, the newly exposed mudflat is colonized by opportunistic non-native species, such as M. insidiosum and the polychaete Streblospio benedicti, making removal of reefs a questionable strategy for control. These results show that provision of habitat by a non-native ecosystem engineer may be a mechanism for invasional meltdown in Elkhorn Slough, and that reefs increase spatial heterogeneity in the abundance and composition of benthic communities.

  5. Metabolism of reduced methylated sulfur compounds in anaerobic sediments and by a pure culture of an estuarine methanogen

    USGS Publications Warehouse

    Kiene, R.P.; Oremland, Ronald S.; Catena, Anthony; Miller, Laurence G.; Capone, D.G.

    1986-01-01

    Addition of dimethylsulfide (DMS), dimethyldisulfide (DMDS), or methane thiol (MSH) to a diversity of anoxic aquatic sediments (e.g., fresh water, estuarine, alkaline/hypersaline) stimulated methane production. The yield of methane recovered from DMS was often 52 to 63%, although high concentrations of DMS (as well as MSH and DMDS) inhibited methanogenesis in some types of sediments. Production of methane from these reduced methylated sulfur compounds was blocked by 2-bromoethanesulfonic acid. Sulfate did not influence the metabolism of millimolar levels of DMS, DMDS, or MSH added to sediments. However, when DMS was added at ∼2-μM levels as [14C]DMS, metabolism by sediments resulted in a 14CH4/14CO2 ratio of only 0.06. Addition of molybdate increased the ratio to 1.8, while 2-bromoethanesulfonic acid decreased it to 0, but did not block 14CO2 production. These results indicate the methanogens and sulfate reducers compete for DMS when it is present at low concentrations; however, at high concentrations, DMS is a “noncompetitive” substrate for methanogens. Metabolism of DMS by sediments resulted in the appearance of MSH as a transient intermediate. A pure culture of an obligately methylotrophic estuarine methanogen was isolated which was capable of growth on DMS. Metabolism of DMS by the culture also resulted in the transient appearance of MSH, but the organism could grow on neither MSH nor DMDS. The culture metabolized [14C]-DMS to yield a 14CH4/14CO2 ratio of ∼2.8. Reduced methylated sulfur compounds represent a new class of substrates for methanogens and may be potential precursors of methane in a variety of aquatic habitats.

  6. Metabolism of reduced methylated sulfur compounds in anaerobic sediments and by a pure culture of an estuarine methanogen

    SciTech Connect

    Kiene, R.P.; Oremland, R.S.; Catena, A.; Miller, L.G.; Capone, A.G.

    1986-11-01

    Addition of dimethylsulfide (DMS), dimethyldisulfide (DMDS), or methane thiol (MSH) to a diversity of anoxic aquatic sediments (e.g., fresh water, estuarine, alkaline/hypersaline) stimulated methane production. The yield of methane recovered from DMS was often 52 to 63%, although high concentrations of DMS (as well as MSH and DMDS) inhibited methanogenesis in some types of sediments. Production of methane from these reduced methylated sulfur compounds was blocked by 2-bromoethanesulfonic acid. Sulfate did not influence the metabolism of millimolar levels of DMS, DMDs, or MSH added to sediments. However, when DMS was added at approx.2-3=M levels as (/sup 14/C)DMS, metabolism by sediments resulted in a /sup 14/CH/sub 4///sup 14/CO/sub 2/ ratio of only 0.06. Addition of molybdate increased the ratio of 1.8, while 2-bromoethanesulfonic acid decreased it to 0, but did not block /sup 14/CO/sub 2/ production. These results indicate the methanogens and sulfate reducers compete for DMS when it is present at low concentrations; however, at high concentrations, DMS is a noncompetitive substrate for methanogens. Metabolism of DMS by sediments resulted in the appearance of MSH as a transient intermediate. A pure culture of an obligately methylotrophic estuarine methanogen was isolated which was capable of growth on DMS. Metabolism of DMS by the culture also resulted in the transient appearance of MSH, but the organism could grow on neither MSH nor DMDS. The culture metabolized (/sup 14/C)-DMS to yield a /sup 14/CH/sub 4///sup 14/CO/sub 2/ ratio of approx. 2.8.

  7. Contemporaneous early diagenetic formation of organic and inorganic sulfur in estuarine sediments from St. Andrew Bay, Florida, USA

    NASA Astrophysics Data System (ADS)

    Brüchert, Volker; Pratt, Lisa M.

    1996-07-01

    Estuarine sediment samples were collected from nine stations in St. Andrew Bay near Panama City, Florida, USA. Contrasting grain size and varying concentration of organic carbon allowed a comparative study of the relationships among organic degradation processes, sulfur cycling, and diagenetic removal of dissolved sulfide produced by bacterial sulfate reduction. Abundance and sulfur isotopic composition were determined for dissolved sulfide, dissolved sulfate, pyrite, humic-acid sulfur, fulvic-acid sulfur, and elemental sulfur. Presence of free dissolved sulfide and enrichment in 34S of porewater sulfate in samples from organic-rich, muddy sediments of St. Andrew Bay indicate high rates of sulfate reduction and anoxic conditions below 5 mm depth. Such conditions are not reflected in samples from organic-poor, sandy, near-shore sediments collected from highly productive areas occupied by seagrass beds. In this estuarine system, pyrite and fulvic-acid sulfur are the largest sinks for sulfide produced by bacterial sulfate reduction. Strong correlation between abundances of pyrite and fulvic-acid sulfur suggests coincident formation in the uppermost 10 cm of sediment. Large differences in isotopic composition between these two species and consistent enrichment in 34S of the fulvic-acid fraction, however, indicate two different reaction pathways. Abundance and sulfur isotopic composition of humic-acid and fulvic-acid sulfur suggest that organic sulfur is derived from mixing between (1) 34S-depleted sulfur with an unknown oxidation state that was recycled from bacterial hydrogen sulfide and (2) 34S-enriched sulfur interpreted as primary biosynthetic sulfur originally assimilated from dissolved sulfate. Samples taken from sandy sediment localities where aquatic vascular plants are rooted in the anoxic zone show a strong depletion in 34S in the fulvic-acid sulfur fraction suggesting recycled hydrogen sulfide as the dominant source of organic sulfur.

  8. Origin and transport of (238)U and (226)Ra in riverine, estuarine and marine sediments of the Krka River, Croatia.

    PubMed

    Cukrov, Neven; Mlakar, Marina; Cuculić, Vlado; Barisić, Delko

    2009-06-01

    Spatial distribution of (238)U and (226)Ra activities in sediment columns along the Krka River and estuary, were studied using gamma spectrometry. Markedly different (238)U and (226)Ra activities between riverine, estuarine and marine sediments were observed. Distribution of these radionuclides, as well as their anthropogenic and natural origin, was evaluated by activity measurements, taking into account sedimentation rates estimated by (137)Cs distribution in sediment columns. Naturally present (238)U and (226)Ra activities were highest in riverine and lowest in marine sediments. (238)U and (226)Ra activities in historic riverine sediments revealed anthropogenic influence from town of Knin, which diminished for 15-20% in 1990s due to warfare that caused stop of industrial, agricultural and transport activities. Drainage of the flysch material naturally elevates (238)U and (226)Ra activities in the vicinity of its inflow in the upper part of estuary. (238)U and (226)Ra from the phosphate ore discharge in the port of Sibenik did not spread further in estuary, which was also confirmed by (238)U and (226)Ra activities detected in Mytilus sp. mussels' tissue.

  9. Pore water distributions of dissolved copper and copper-complexing ligands in estuarine and coastal marine sediments

    SciTech Connect

    Skrabal, S.A.; Donat, J.R.; Burdige, D.J.

    2000-06-01

    The distributions and seasonal variability of total dissolved Cu (TDCu) and Cu-complexing ligands in sediment pore waters have been investigated at two contrasting sites in the Chesapeake Bay. Two ligand classes, which differ on the basis of the conditional stability constants (K{prime}{sub cond}) of their Cu complexes, were detected at all depths at both sites. For comparison, one pore water profile from a slope station off of the Chesapeake Bay also showed the presence of two ligand classes. Virtually all TDCu fluxing from these sediments is complexed during sediment-water exchange. A relatively small fraction of the TDCu is exchanged as inorganic species, which are widely regarded as the most bioavailable form of Cu. Total ligand concentrations are 15 to >100 times higher in the upper intervals of the pore waters relative to ligand concentrations in the bottom waters of the Chesapeake Bay (30--60 nM), consistent with previous observations of fluxes of these ligands from the sediments to overlying waters. These results suggest that sediments are potentially significant sources of Cu-complexing ligands to the overlying waters of the Chesapeake Bay, and perhaps, other shallow water estuarine and coastal environments. Copper-complexing ligands released from sediment pore waters may play an important role in influencing Cu speciation in overlying waters.

  10. Micro-spatial variation of elemental distribution in estuarine sediment and their accumulation in mangroves of Indian Sundarban.

    PubMed

    Bakshi, Madhurima; Ram, S S; Ghosh, Somdeep; Chakraborty, Anindita; Sudarshan, M; Chaudhuri, Punarbasu

    2017-05-01

    This work describes the micro-spatial variation of elemental distribution in estuarine sediment and bioaccumulation of those elements in different mangrove species of the Indian Sundarbans. The potential ecological risk due to such elemental load on this mangrove-dominated habitat is also discussed. The concentrations of elements in mangrove leaves and sediments were determined using energy-dispersive X-ray fluorescence spectroscopy. Sediment quality and potential ecological risks were assessed from the calculated indices. Our data reflects higher concentration of elements, e.g., Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, and Pb, in the sediment, as compared to that reported by earlier workers. Biological concentration factors for K, Ca, Mn, Fe, Cu, and Zn in different mangroves indicated gradual elemental bioaccumulation in leaf tissues (0.002-1.442). Significant variation was observed for elements, e.g., Ni, Mn, and Ca, in the sediments of all the sites, whereas in the plants, significant variation was found for P, S, Cl, K, Ca, Mn, Fe, Cu, and Zn. This was mostly due to the differences in uptake and accumulation potential of the plants. Various sediment quality indices suggested the surface sediments to be moderately contaminated and suffering from progressive deterioration. Cu, Cr, Zn, Mn, and Ni showed higher enrichment factors (0.658-1.469), contamination factors (1.02-2.7), and geo-accumulation index (0.043-0.846) values. The potential ecological risk index values considering Cu, Cr, Pb, and Zn were found to be within "low ecological risk" category (20.04-24.01). However, Cr and Ni in the Sundarban mangroves exceeded the effect range low and probable effect level limits. Strong correlation of Zn with Fe and K was observed, reflecting their similar transportation and accumulation process in both sediment and plant systems. The plant-sediment elemental correlation was found to be highly non-linear, suggesting role of some physiological and edaphic factors in

  11. Arcobacter anaerophilus sp. nov., isolated from an estuarine sediment and emended description of the genus Arcobacter.

    PubMed

    Sasi Jyothsna, T S; Rahul, K; Ramaprasad, E V V; Sasikala, Ch; Ramana, Ch V

    2013-12-01

    Two strains (JC83, JC84(T)) of obligately anaerobic, H2S-producing bacteria were isolated from estuarine sediment samples collected from Gangasagar, West Bengal, India. Cells were Gram-stain-negative, non-motile rods. Both strains were positive for oxidase, negative for catalase, hydrolysed casein, reduced nitrate and utilized citrate. Both strains grew chemoorganoheterotrophically with optimal pH of 7-8 (range 7-10) and at 30 °C (range 25-37 °C). C16 : 1ω7c, C18 : 1ω7c, C16 : 0 and C12 : 0 were the major fatty acids of both strains with minor amounts of C14 : 0, C12 : 0 3-OH and C18 : 0. Polar lipids of both strains included diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylserine, phosphatidylcholine, phosphatidylinositol, an unidentified aminolipid (AL2), an unidentified phospholipid (PL2) and an unidentified lipid (L3). MK-6 was the major respiratory quinone. The DNA G+C content of strains JC83 and JC84(T) was 25.0 and 24.6 mol%, respectively. The strains showed DNA reassociation >85 % (86.0±0.5 %) (based on DNA-DNA hybridization). Based on 16S rRNA gene sequence analysis, both strains were identified as belonging to the family Campylobacteraceae of the class Epsilonproteobacteria with Arcobacter marinus CL-S1(T) (95.4 % sequence similarity) as their closest phylogenetic neighbour. On the basis of morphological, physiological and chemotaxonomic characteristics as well as phylogenetic analysis, strains JC83 and JC84(T) are considered to represent a novel species, for which the name Arcobacter anaerophilus sp. nov. is proposed. The type strain is JC84(T) ( = KCTC 15071(T) = MTCC 10956(T) = DSM 24636(T)). An emended description of the genus Arcobacter is provided.

  12. Stratified active archaeal communities in the sediments of Jiulong River estuary, China.

    PubMed

    Li, Qianqian; Wang, Fengping; Chen, Zhiwei; Yin, Xijie; Xiao, Xiang

    2012-01-01

    Here the composition of total and active archaeal communities in a sediment core of Jiulong River estuary at Fujian Province, Southern China was reported. Profiles of CH(4) and SO(2-) (4) concentrations from the sediment core indicated the existence of a sulfate-methane transition zone (SMTZ) in which sulfate reduction-coupled anaerobic oxidation of methane (AOM) occurs. Accordingly, three sediment layers (16-18.5 cm, 71-73.5 cm, and 161-163.5 cm) from the 1.2 m sediment core were sectioned and named top, middle and bottom, respectively. Total DNA and RNA of each layer were extracted and used for clone libraries and sequence analysis of 16S rRNA genes, the reverse transcription (RT)-PCR products of 16S rRNA and methyl CoM reductase alpha subunit (mcrA) genes. Phylogenetic analysis indicated that archaeal communities of the three layers were dominated by the Miscellaneous Crenarchaeotal Group (MCG) whose ecological functions were still unknown. The MCG could be further divided into seven subgroups, named MCG-A, B, C, D, E, F, and G. MCG-A and MCG-G were the most active groups in the estuarine sediments. Known anaerobic methanotrophic archaea (ANMEs) were only found as minor components in these estuarine archaeal communities. This study, together with the studies of deep subsurface sediments, would be a very good start point to target and compare the specific active archaeal groups and their roles in the dark, deep subsurface sediment environments.

  13. Speciation and Fate of Trace Metals in Estuarine Sediments Under Reduced and Oxidized Conditions, Seaplane Lagoon, Alameda Naval Air Station

    SciTech Connect

    Carroll, S A; Day, P A; Esser, B; Randall, S

    2002-10-18

    We have identified important chemical reactions that control the fate of metal-contaminated estuarine sediments if they are left undisturbed (in situ) or if they are dredged. We combined information on the molecular bonding of metals in solids from X-ray absorption spectroscopy (XAS) with thermodynamic and kinetic driving forces obtained from dissolved metal concentrations to deduce the dominant reactions under reduced and oxidized conditions. We evaluated the in situ geochemistry of metals (cadmium, chromium, iron, lead, manganese and zinc) as a function of sediment depth (to 100 cm) from a 60-year record of contamination at the Alameda Naval Air Station, California. Results from XAS and thermodynamic modeling of porewaters show that cadmium and most of the zinc form stable sulfide phases, and that lead and chromium are associated with stable carbonate, phosphate, phyllosilicate, or oxide minerals. Therefore, there is minimal risk associated with the release of these trace metals from the deeper sediments contaminated prior to the Clean Water Act (1975) as long as reducing conditions are maintained. Increased concentrations of dissolved metals with depth were indicative of the formation of metal HS- complexes. The sediments also contain zinc, chromium, and manganese associated with detrital iron-rich phyllosilicates and/or oxides. These phases are recalcitrant at near-neutral pH and do not undergo reductive dissolution within the 60-year depositional history of sediments at this site. The fate of these metals during dredging was evaluated by comparing in situ geochemistry with that of sediments oxidized by seawater in laboratory experiments. Cadmium and zinc pose the greatest hazard from dredging because their sulfides were highly reactive in seawater. However, their dissolved concentrations under oxic conditions were limited eventually by sorption to or co-precipitation with an iron (oxy)hydroxide. About 50% of the reacted CdS and 80% of the reacted ZnS were

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

    PubMed

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

    2012-01-01

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

  15. Assessment of the genotoxic potential of contaminated estuarine sediments in fish peripheral blood: laboratory versus in situ studies.

    PubMed

    Costa, Pedro M; Neuparth, Teresa S; Caeiro, Sandra; Lobo, Jorge; Martins, Marta; Ferreira, Ana M; Caetano, Miguel; Vale, Carlos; DelValls, T Angel; Costa, Maria H

    2011-01-01

    Juvenile Senegalese soles (Solea senegalensis) were exposed to estuarine sediments through 28-day laboratory and in situ (field) bioassays. The sediments, collected from three distinct sites (a reference plus two contaminated) of the Sado Estuary (W Portugal) were characterized for total organic matter, redox potential, fine fraction and for the levels of metals, polycyclic aromatic hydrocarbons (PAHs) and organochlorines, namely polychlorinated biphenyls (PCBs) and dichloro diphenyl tricholoethane plus its main metabolites (DDTs). Genotoxicity was determined in whole peripheral blood by the single-cell gel electrophoresis (SCGE or "comet") assay and by scoring erythrocytic nuclear abnormalities (ENA). Analysis was complemented with the determination of lipid peroxidation in blood plasma by the thiobarbituric acid reactive substances (TBARS) protocol and cell type sorting. The results showed that exposure to contaminated sediments induced DNA fragmentation and clastogenesis. Still, laboratory exposure to the most contaminated sediment revealed a possible antagonistic effect between metallic and organic contaminants that might have been enhanced by increased bioavailability. The laboratory assay caused a more pronounced increase in ENA whereas a very significant increase in DNA fragmentation was observed in field-tested fish exposed to the reference sediment, which is likely linked to increased lipid peroxidation that probably occurred due to impaired access to food. Influence of natural pathogens was ruled out by unaltered leukocyte counts. The statistical integration of data correlated lipid peroxidation with biological variables such as fish length and weight, whereas the genotoxicity biomarkers were more correlated to sediment contamination. It was demonstrated that laboratory and field bioassays for the risk assessment of sediment contamination may yield different genotoxicity profiles although both provided results that are in overall accordance with sediment

  16. Polychlorinated dibenzo-p-dioxin and dibenzofuran residues in estuarine and coastal North Sea sediments: Sources and distribution

    SciTech Connect

    Evers, E.H.G.; Klamer, H.J.C.; Laane, R.W.P.M. . Ministry of Transport, Public Works and Water Management); Govers, H.A.J. . Dept. of Environmental and Toxicological Chemistry)

    1993-09-01

    Sediments from two depositional zones of the North Sea (the Wadden Sea and Oyster Grounds) and from the estuaries of the rivers Rhine, Meuse, Scheldt, Ems, and Humber were analyzed for polychlorinated dibenzofurans (PCDFs) and dibenzo-p-dioxins (PCDDs) using a congener-specific procedure. A simple grain-size correction procedure was utilized for the comparison of PCDF and PCDD concentrations in sediments from different origin. PCDFs were more widely encountered than PCDDs in all sediments, except for the Ems-Dollard and the Humber estuary. The highest concentrations were found in the outflow sediments of the rivers Rhine and Humber. Concentrations up to 2,980 ng/kg PCDFs, principally 1,2,3,4,6,7,8-HpCDF and OCDF, and up to 1,760 ng/kg PCDDs, principally OCDD, were determined in the River Rhine sediments. Principal component analysis was used to visualize the compositional changes of Rhine sediments. Principal component analysis was used to visualize the compositional changes of PCDD and PCDF profiles in the sediments. Two-dimensional projections based on sample scores from the principal component models showed a marked influence of the River Rhine on the presence of these compounds in the western Wadden Sea and the Oyster Grounds. Based on a chemometric evaluation of chromatographic profiles of these coastal, estuarine and related freshwater sediments, the authors have deduced that these compounds originate from industrial operation discharges, related to the production of chloroaliphatic compounds and the chloralkali compounds and the chloralkali industry along the River Rhine. The atmospheric deposition of combustion-generated PCDDs and PCDFs appeared significant only for remote marine environments.

  17. Determining oxidative and non-oxidative genotoxic effects driven by estuarine sediment contaminants on a human hepatoma cell line.

    PubMed

    Pinto, M; Costa, P M; Louro, H; Costa, M H; Lavinha, J; Caeiro, S; Silva, M J

    2014-04-15

    Estuarine sediments may be reservoirs of hydrophilic and hydrophobic pollutants, many of which are acknowledged genotoxicants, pro-mutagens and even potential carcinogens for humans. Still, studies aiming at narrowing the gap between ecological and human health risk of sediment-bound contaminant mixtures are scarce. Taking an impacted estuary as a case study (the Sado, SW Portugal), HepG2 (human hepatoma) cells were exposed in vitro for 48 h to extracts of sediments collected from two areas (urban/industrial and Triverine/agricultural), both contaminated by distinct mixtures of organic and inorganic toxicants, among which are found priority mutagens such as benzo[a]pyrene. Comparatively to a control test, extracts of sediments from both impacted areas produced deleterious effects in a dose-response manner. However, sediment extracts from the industrial area caused lower replication index plus higher cytotoxicity and genotoxicity (concerning total DNA strand breakage and clastogenesis), with emphasis on micronucleus induction. On the other hand, extracts from the rural area induced the highest oxidative damage to DNA, as revealed by the FPG (formamidopyrimidine-DNA glycosylase) enzyme in the Comet assay. Although the estuary, on its whole, has been classified as moderately contaminated, the results suggest that the sediments from the industrial area are significantly genotoxic and, furthermore, elicit permanent chromosome damage, thus potentially being more mutagenic than those from the rural area. The results are consistent with contamination by pro-mutagens like polycyclic aromatic hydrocarbons (PAHs), potentiated by metals. The sediments from the agriculture-influenced area likely owe their genotoxic effects to metals and other toxicants, probably pesticides and fertilizers, and able to induce reactive oxygen species without the formation of DNA strand breakage. The findings suggest that the mixtures of contaminants present in the assayed sediments are genotoxic

  18. Assessment of the genotoxic potential of contaminated estuarine sediments in fish peripheral blood: Laboratory versus in situ studies

    SciTech Connect

    Costa, Pedro M.; Neuparth, Teresa S.; Caeiro, Sandra; Lobo, Jorge; Martins, Marta; Ferreira, Ana M.; Caetano, Miguel; Vale, Carlos; Angel DelValls, T.

    2011-01-15

    Juvenile Senegalese soles (Solea senegalensis) were exposed to estuarine sediments through 28-day laboratory and in situ (field) bioassays. The sediments, collected from three distinct sites (a reference plus two contaminated) of the Sado Estuary (W Portugal) were characterized for total organic matter, redox potential, fine fraction and for the levels of metals, polycyclic aromatic hydrocarbons (PAHs) and organochlorines, namely polychlorinated biphenyls (PCBs) and dichloro diphenyl tricholoethane plus its main metabolites (DDTs). Genotoxicity was determined in whole peripheral blood by the single-cell gel electrophoresis (SCGE or 'comet') assay and by scoring erythrocytic nuclear abnormalities (ENA). Analysis was complemented with the determination of lipid peroxidation in blood plasma by the thiobarbituric acid reactive substances (TBARS) protocol and cell type sorting. The results showed that exposure to contaminated sediments induced DNA fragmentation and clastogenesis. Still, laboratory exposure to the most contaminated sediment revealed a possible antagonistic effect between metallic and organic contaminants that might have been enhanced by increased bioavailability. The laboratory assay caused a more pronounced increase in ENA whereas a very significant increase in DNA fragmentation was observed in field-tested fish exposed to the reference sediment, which is likely linked to increased lipid peroxidation that probably occurred due to impaired access to food. Influence of natural pathogens was ruled out by unaltered leukocyte counts. The statistical integration of data correlated lipid peroxidation with biological variables such as fish length and weight, whereas the genotoxicity biomarkers were more correlated to sediment contamination. It was demonstrated that laboratory and field bioassays for the risk assessment of sediment contamination may yield different genotoxicity profiles although both provided results that are in overall accordance with sediment

  19. Anthropogenic Influences on Estuarine Sedimentation and Ecology: Examples from Varved Sediments of the Pettaquanscutt River Estuary, Rhode Island

    EPA Science Inventory

    Estuaries and lakes are undergoing anthropogenic alterations as development and industry intensify in the modern world. Assessing the ecological health of such water bodies is difficult because accurate accounts of pre-anthropogenic estuarine/lacustrine conditions do not exist. S...

  20. Anthropogenic Influences on Estuarine Sedimentation and Ecology: Examples from Varved Sediments of the Pettaquanscutt River Estuary, Rhode Island

    EPA Science Inventory

    Estuaries and lakes are undergoing anthropogenic alterations as development and industry intensify in the modern world. Assessing the ecological health of such water bodies is difficult because accurate accounts of pre-anthropogenic estuarine/lacustrine conditions do not exist. S...

  1. Size-selective toxicity effects of the antimicrobial tylosin on estuarine phytoplankton communities.

    PubMed

    Kline, Allison; Pinckney, James L

    2016-09-01

    The purpose of this study was to determine the lethal and sublethal effects of the antimicrobial tylosin on natural estuarine phytoplankton communities. Bioassays were used in experimental treatments with final concentrations of 5 to 1000 μg tylosin l(-1). Maximum percent inhibition ranged from 57 to 85% at concentrations of 200-400 μg tylosin l(-1). Half maximum inhibition concentrations of tylosin were ca. 5x lower for small phytoplankton (<20 μm) relative to larger phytoplankton (>20 μm) and suggests that small phytoplankton are more sensitive to tylosin exposure. Sublethal effects occurred at concentrations as low as 5 μg tylosin l(-1). Environmental concentrations of tylosin (e.g., 0.2-3 μg l(-1)) may have a significant sublethal effect that alters the size structure and composition of phytoplankton communities. The results of this study highlight the potential importance of cell size on toxicity responses of estuarine phytoplankton. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Transgressive Holocene sequence recorded in Steinhatchee estuarine sediments: Western peninsular Florida

    SciTech Connect

    Garrett, C.B.; Hoenstine, R.W.; Hertler, H.A.; Highley, A.B. ); Donoghue, J.D. . Geology Dept.)

    1994-03-01

    The flat regional topography of peninsular Florida's Gulf Coast reflects the shallow dip of the underlying carbonate platform. As a result of this low gradient, wave energy is generally low and sedimentation within the Steinhatchee Estuary is dominated by river- and tidal-hydrodynamics. Carbonate dissolution has caused the Eocene-aged limestone surface to be highly irregular. The transgressive sequence unconformably overlying this karstic surface is comprised of clastics, from upriver and offshore, and organics produced by reefal and salt-marsh communities. Sequences deposited in karstic lows are up to 7 meters (m) thick. More typical sequences are 3 m thick, or less. The oldest unlithified marsh strata include dolosilt or carbonate rubble with clay and wood fragments. This clayey rubble-zone is overlain by subaerially deposited reddish-brown clayey sands and organic sands (including buried trees) which are in turn overlain by black, organic-rich, peaty, wetland deposits. These marsh sequences are primarily sand, which fines upwards. Silt-sized (and smaller) clastics and organic components increase up-sequence at similar rates. Thin sequences (.3--.5 m) of shelly organic-rich sand occur in current submarine environments. Thicker submarine sequences (up to 7 m) of similar material occur in present or relic oyster bars. Although a basal clayey rubble-zone may be present, subaerial and/or wetlands facies are not observed in offshore sediments. Erosion of these facies as sea level rose may have resulted from insufficient sediment supply to maintain the beach profile and/or from down-cutting by tidal currents.

  3. An integrative assessment to determine the genotoxic hazard of estuarine sediments: combining cell and whole-organism responses

    PubMed Central

    Costa, Pedro M.; Pinto, Miguel; Vicente, Ana M.; Gonçalves, Cátia; Rodrigo, Ana P.; Louro, Henriqueta; Costa, Maria H.; Caeiro, Sandra; Silva, Maria J.

    2014-01-01

    The application of the Comet assay in environmental monitoring remains challenging in face of the complexity of environmental stressors, e.g., when dealing with estuarine sediments, that hampers the drawing of cause-effect relationships. Although the in vitro Comet assay may circumvent confounding factors, its application in environmental risk assessment (ERA) still needs validation. As such, the present work aims at integrating genotoxicity and oxidative DNA damage induced by sediment-bound toxicants in HepG2 cells with oxidative stress-related effects observed in three species collected from an impacted estuary. Distinct patterns were observed in cells exposed to crude mixtures of sediment contaminants from the urban/industrial area comparatively to the ones from the rural/riverine area of the estuary, with respect to oxidative DNA damage and oxidative DNA damage. The extracts obtained with the most polar solvent and the crude extracts caused the most significant oxidative DNA damage in HepG2 cells, as measured by the formamidopyrimidine-DNA glycosylase (FPG)-modified Comet assay. This observation suggests that metals and unknown toxicants more hydrophilic than polycyclic aromatic hydrocarbons may be important causative agents, especially in samples from the rural part of the estuary, where oxidative DNA damage was the most significant. Clams, sole, and cuttlefish responded differentially to environmental agents triggering oxidative stress, albeit yielding results accordant with the oxidative DNA damage observed in HepG2 cells. Overall, the integration of in vivo biomarker responses and Comet assay data in HepG2 cells yielded a comparable pattern, indicating that the in vitro FPG-modified Comet assay may be an effective and complementary line-of-evidence in ERA even in particularly challenging, natural, scenarios such as estuarine environments. PMID:25540652

  4. Factors affecting metal exchange between sediment and water in an estuarine reservoir: a spatial and seasonal observation.

    PubMed

    Kang, Joo-Hyon; Lee, Young Geun; Lee, Keun-Young; Cha, Sung Min; Cho, Kyung Hwa; Lee, Yun Seok; Ki, Seo Jin; Yoon, In-Ho; Kim, Kyoung-Woong; Kim, Joon Ha

    2009-11-01

    Water quality response in a reservoir has often been assessed using relatively restricted datasets that cannot provide sufficient information, thereby giving rise to a dramatic over- or underestimate of actual figures. In this paper we discuss how the levels of metallic elements between the sediment and overlying water in an estuarine reservoir can be influenced by aquatic parameters in response to spatial and seasonal conditions. To better elucidate the interfacial exchange between sediment and water, statistical analyses are employed to intensive data sets collected from the Yeongsan Reservoir (YSR), Korea, which has undergone widespread deterioration in water quality due to the continuous growth of anthropogenic sources. During three seasonal sampling campaigns, we found that oxygen deficiency at the bottom water layer promotes Fe and Ni accumulation in sediment, likely due to the formation of sulfide and oxide complexes under anoxic and suboxic environments, respectively. In addition, salinity levels as high as 11 per thousand in the bottom water layer during autumn substantially increase the release of Mn, restricting the use of YSR as a primary source of agricultural irrigation water. Although most dissolved metals are at acceptable levels for sustaining aquatic life, it is recommended that for long-term planning the elevated Fe and Mn levels in sediment should be controlled with oxygen deficiency during dry weather to ensure a sustainable water supply or, at a minimum, better coordinated operation of YSR.

  5. Low Functional β-Diversity Despite High Taxonomic β-Diversity among Tropical Estuarine Fish Communities

    PubMed Central

    Villéger, Sébastien; Miranda, Julia Ramos; Hernandez, Domingo Flores; Mouillot, David

    2012-01-01

    The concept of β-diversity, defined as dissimilarity among communities, has been widely used to investigate biodiversity patterns and community assembly rules. However, in ecosystems with high taxonomic β-diversity, due to marked environmental gradients, the level of functional β-diversity among communities is largely overlooked while it may reveal processes shaping community structure. Here, decomposing biodiversity indices into α (local) and γ (regional) components, we estimated taxonomic and functional β-diversity among tropical estuarine fish communities, through space and time. We found extremely low functional β-diversity values among fish communities (<1.5%) despite high dissimilarity in species composition and species dominance. Additionally, in contrast to the high α and γ taxonomic diversities, α and γ functional diversities were very close to the minimal value. These patterns were caused by two dominant functional groups which maintained a similar functional structure over space and time, despite the strong dissimilarity in taxonomic structure along environmental gradients. Our findings suggest that taxonomic and functional β-diversity deserve to be quantified simultaneously since these two facets can show contrasting patterns and the differences can in turn shed light on community assembly rules. PMID:22792395

  6. Evaluation of Reduced Sediment Volume Procedures for Acute Toxicity Tests Using the Estuarine Amphipod Leptocheirus plumulosus

    EPA Science Inventory

    The volume of sediment required to perform a sediment toxicity bioassay is a major driver of the overall cost associated with that bioassay. Sediment volume affects bioassay cost due to sediment collection, transportation, storage, and disposal costs as well as labor costs assoc...

  7. Evaluation of Reduced Sediment Volume Procedures for Acute Toxicity Tests Using the Estuarine Amphipod Leptocheirus plumulosus

    EPA Science Inventory

    The volume of sediment required to perform a sediment toxicity bioassay is a major driver of the overall cost associated with that bioassay. Sediment volume affects bioassay cost due to sediment collection, transportation, storage, and disposal costs as well as labor costs assoc...

  8. The effects of fine-scale substratum roughness on diatom community structure in estuarine biofilms.

    PubMed

    Sweat, L Holly; Johnson, Kevin B

    2013-09-01

    Benthic diatoms are a major component of biofilms that form on surfaces submerged in marine environments. Roughness of the underlying substratum affects the settlement of both diatoms and subsequent macrofouling colonizers. This study reports the effects of roughness on estuarine diatom communities established in situ in the Indian River Lagoon, FL, USA. Natural communities were established on acrylic panels with a range of surface roughnesses. Smoother substrata exhibited higher cell density, species richness, and diversity. Twenty-three of 58 species were found either exclusively or more abundantly on the smooth surfaces compared to one or both roughened treatments. The results suggest a greater ability of benthic diatoms to recruit and colonize smooth surfaces, which is probably explained by a higher degree of contact between the cells and the surface.

  9. Elemental status in sediment and American oyster collected from Savannah marsh/estuarine ecosystem: a preliminary assessment.

    PubMed

    Sajwan, Kenneth S; Kumar, Kurunthachalam Senthil; Paramasivam, Sivapatham; Compton, Sanya S; Richardson, Joseph P

    2008-02-01

    Sediment and American oyster (Crassostrea virginica) collected from nine selected marsh/estuarine ecosystems in Savannah, Georgia were analyzed for elements such as Al, As, B, Cd, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Si, and Zn. Sediments were extracted by ammonium acetate (NH(4)OAc), Mehlich-3 (M-3), and water procedures, whereas an acid digestion procedure was adopted for oyster tissue. Concentrations of elements were higher in M-3 extractions followed by NH(4)OAc and water extraction procedures. Calcium and Mg was greater in sediments by any of the extractions, whereas other elements differed depending upon the extraction procedures. There were no significant spatial variations (p < 0.05) of any of elements analyzed except Mn, in NH(4)OAc/water extraction procedure and Fe and Al by water extraction procedure. Contamination of Al, B, Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Si, and Zn in oyster tissue ranged from 399 to 1460, 231 to 254, <1.5 to 2.9, <1.5 to 8.0, 67 to 121, 232 to 1357, 17 to 54, <0.5 to 0.64, <1.5 to 2.5, <1.5 to 4.0, 241 to 381, and 978 to 2428 microg/g dry weight (dw), respectively. Greatly elevated concentrations of elements such as P, Ca, Mg, K, and S were noticed in oyster tissue. The concentration range of Hg and As in sediment was 1.2-1.9 and 11-55 microg/g dw, respectively. The concentration range of Hg and As in oyster tissue was 130-908 and 200-912 ng/g dw, respectively. With the exception of As and Hg, other elements are several orders of magnitude greater in oyster tissue. There is no significant (p < 0.05) contamination variation in target analyses between the nine selected sites. Concentrations of heavy metals in sediment and oyster were either comparable or lower than those of other countries. Greater biota-sediment accumulation factor was noticed for P and Zn. Concentrations of Hg and P in oyster tissue were higher than the threshold limit for human consumption. Overall, the baseline data can be used for regular ecological monitoring

  10. Incremental ecological exposure risks from contaminated sediments in an urban estuarine river.

    PubMed

    Ludwig, David F; Iannuzzi, Timothy J

    2005-11-01

    Estuaries in urban regions present unique environmental management challenges. Ecosystems in urban estuaries are typically impacted by habitat loss and degradation, watershed modification, and nonpoint and point sources of many chemicals. Restoring such systems requires an understanding of the relative contribution of various stressors to overall ecological conditions and an understanding of shifting patterns of stress over time. In this article, we present the results of a multiparameter environmental assessment of a quintessential urbanized waterway: the lower Passaic River in the vicinity of Newark, New Jersey, USA. To provide the foundation for effective management decision making, we quantified baseline conditions (habitat losses and degradation), chemical concentrations in sediment and biota relative to published toxic effect levels, direct toxicity of sediments to benthic organisms, and food-web mediated risks to fish-eating birds. Habitat losses have been severe (greater than 85% of wetlands, nearly 100% of the total length of tidal and nontidal tributaries, and 100% of natural shoreline habitat have been lost), resulting in substantial habitat constraints on biota. Despite this, biological communities are present in the lower Passaic. In general, concentrations of toxic chemicals in surface sediments have fallen with time, and natural recovery processes are proceeding. Chemical concentrations remain high enough to impair survival of amphipods, but not amphipod growth or polychaete growth or survival as measured in laboratory bioassays using field-collected sediment. Fish and blue crab body burdens of some metals, PCBs, and the pesticide, DDT, are at concentrations sufficiently high to exceed toxicity thresholds. The resident fish-eating bird--the belted kingfisher--is at exposure risk from some metals, PCBs, and polychlorinated dibenzo-p-dioxins and dibenzo furans (PCDD/Fs). Migratory waders--the herons and egrets--are not at risk from chemical exposure

  11. Multi Length Scale Imaging of Flocculated Estuarine Sediments; Insights into their Complex 3D Structure

    NASA Astrophysics Data System (ADS)

    Wheatland, Jonathan; Bushby, Andy; Droppo, Ian; Carr, Simon; Spencer, Kate

    2015-04-01

    Suspended estuarine sediments form flocs that are compositionally complex, fragile and irregularly shaped. The fate and transport of suspended particulate matter (SPM) is determined by the size, shape, density, porosity and stability of these flocs and prediction of SPM transport requires accurate measurements of these three-dimensional (3D) physical properties. However, the multi-scaled nature of flocs in addition to their fragility makes their characterisation in 3D problematic. Correlative microscopy is a strategy involving the spatial registration of information collected at different scales using several imaging modalities. Previously, conventional optical microscopy (COM) and transmission electron microscopy (TEM) have enabled 2-dimensional (2D) floc characterisation at the gross (> 1 µm) and sub-micron scales respectively. Whilst this has proven insightful there remains a critical spatial and dimensional gap preventing the accurate measurement of geometric properties and an understanding of how structures at different scales are related. Within life sciences volumetric imaging techniques such as 3D micro-computed tomography (3D µCT) and focused ion beam scanning electron microscopy [FIB-SEM (or FIB-tomography)] have been combined to characterise materials at the centimetre to micron scale. Combining these techniques with TEM enables an advanced correlative study, allowing material properties across multiple spatial and dimensional scales to be visualised. The aims of this study are; 1) to formulate an advanced correlative imaging strategy combining 3D µCT, FIB-tomography and TEM; 2) to acquire 3D datasets; 3) to produce a model allowing their co-visualisation; 4) to interpret 3D floc structure. To reduce the chance of structural alterations during analysis samples were first 'fixed' in 2.5% glutaraldehyde/2% formaldehyde before being embedding in Durcupan resin. Intermediate steps were implemented to improve contrast and remove pore water, achieved by the

  12. Can Human-made Saltpans Represent an Alternative Habitat for Shorebirds? Implications for a Predictable Loss of Estuarine Sediment Flats

    NASA Astrophysics Data System (ADS)

    Dias, Maria P.; Lecoq, Miguel; Moniz, Filipe; Rabaça, João E.

    2014-01-01

    Estuarine areas worldwide are under intense pressure due to human activities such as upstream dam building. Shorebirds strongly depend on estuarine intertidal flats during migration and wintering periods and so are particularly vulnerable to such impacts, whose magnitude will depend on the availability of alternative feeding habitats. In this study we analyze if man-made saltpans can represent an alternative habitat for wintering and migrating shorebirds in the Guadiana estuary, a wetland that is already experiencing environmental changes due to the building of the Alqueva reservoir, the largest in Western Europe. We compared the use of mudflats and saltpans as feeding areas by several shorebird species before the construction of the dam. A dataset with 26 years of counts data was also analyzed in order to detect any long-term trend in shorebirds abundance. We concluded that saltpans, in particular the fully mechanized, can be used as an alternative habitat by larger species during winter and southward migration, thus playing a major role in minimizing the possible effects of sediment loss due to dam building. In contrast, smaller species were particularly dependent on mudflats to feed. A significant change in population trends, from positive to negative, was detected for two species. Although we still have no evidence that this is directly linked to dam building, this result and documented changes that limit primary productivity justifies the implementation of a long-term monitoring scheme of shorebird populations in this estuary. We also reinforce the need to manage the saltpans as key habitats for shorebirds.

  13. Structure of the zooplankton communities in the region of the Ob River's estuarine frontal zone

    NASA Astrophysics Data System (ADS)

    Flint, M. V.; Semenova, T. N.; Arashkevich, E. G.; Sukhanova, I. N.; Gagarin, V. I.; Kremenetskiy, V. V.; Pivovarov, M. A.; Soloviev, K. A.

    2010-10-01

    The studies were carried out on September 27-30, 2007, in the area of the Ob estuarine frontal zone and over the adjacent inner Kara Sea shelf. Based upon the latitudinal changes in the salinity, the 100 nautical mile wide estuarine frontal zone was marked out. The frontal zone was inhabited by a specific zooplankton community dominated by species that occurred outside the frontal zone in only minor amounts. The biomass of the mesozooplankton averaging 984 mg/m3 in the frontal zone exceeded by 1.5 and 6 times the corresponding values in the inner desalinated area of the estuary and the adjacent areas of the Kara Sea shelf. At the inner southern periphery of the frontal zone, at maximal latitudinal salinity gradients (>2 psu per mile), the maximal development of the mesoplankton with the mean biomass for the water column of 3.1 g/m3 (37 g/m2) and up to 5.8 g/m3 in the subpycnocline layer was observed. The latitudinal extension of the biomass in the maximum zone did not exceed 10 miles. More than 90% of the maximum was composed of herbivorous zooplankton with the strong domination of the copepod Limnocalanus macrurus. The daily consumption within the zooplankton maximum area was estimated at 820 mgC/m2 per day. This value exceeds by two orders of magnitude the local primary production. At that level of consumption, the available phytoplankton biomass was consumed by grazers in less than 8 hours (!). A zooplankton aggregation at the southern periphery of the estuarine front exists due to the advection of phytoplankton from the adjacent river zone. The aggregation forms a natural pelagic biofilter where new allochthonous organic matter delivered by the river flow is accumulated and high secondary production is formed on its basis. An anomalously high concentration of planktic predatory Parasagitta elegans with biomass of over 1 g/m3 (46% of the total zooplankton biomass) was associated with the outer northern periphery of the estuarine frontal zone.

  14. What multi-beam bathymetric data can tell about morphodynamics and sediment transport in an estuarine environment?

    NASA Astrophysics Data System (ADS)

    Winterscheid, Axel; Reiß, Marcel

    2017-04-01

    The Elbe River Estuary is one of the most important waterways for commercial shipping in Europe. It connects the North Sea with the Port of Hamburg located about 100 km inlands. To secure navigation, the Federal Waterways and Shipping Administration (WSV) is operating a fleet of survey vessels all equipped with a multi-beam echo sounder controlling the required water depths. Beyond navigational purposes, this monitoring is creating a comprehensive and ever-growing data base, which can be used for a consistent morphodynamical description of the river bed. The history of multi-beam records in the Elbe River Estuary reaches back to 2008. At particular river sections where large amounts of fine grained sediments accumulate surveys are taken biweekly; at other sections there are monthly surveys. Locally, sedimentation rates of up to 12 cm per day have been observed within the fairway. The time series of multiple multi-beam records have been analyzed with a particular focus on morphodynamics and sedimentation rates. Here we compare the morphodynamical characteristics of two river sections. The first section is located at the downstream end of the estuarine turbidity zone near the city of Cuxhaven; the second section is located 50 km away at the upstream end of the turbidity zone near the city of Hamburg. These two sections have been selected because in both the morphology of the river bed and the sedimentation processes are strongly influenced by the presence of fine grained sediments. The results show that changing sedimentation rates in both sections are conditioned by different site specific factors, e.g. the dynamic shifting of the turbidity zone along the estuary, which is resulting in a temporarily higher availability of suspended sediments and more intense sedimentation rates in the upper part of the estuary and the respective section. In contrast, in the downstream located river section more intense sedimentation rates could be related to periods of strong north

  15. Cadmium dynamics in estuarine sediments: Effects of salinity and lugworm bioturbation

    SciTech Connect

    Rasmussen, A.D.; Banta, G.T.; Andersen, O.

    2000-02-01

    The authors investigated the effects of lugworm bioturbation on the fate of Cd added either to a thin layer at the sediment surface or homogeneously mixed throughout the sediment. In both situations, the Cd release to the overlying water was highest when lugworms were not present, most likely because bioturbation transported Cd-contaminated sediment away from the sediment surface. Also, irrigation transported water-borne Cd back into the sediment. When Cd was added to the sediment surface, a Cd peak emerged at the feeding depth of the worm within 1 d because of the transport of water-borne Cd down into the sediment by lugworm irrigation. In addition, the conveyor-belt feeding mode of the worm caused both burial of Cd by fecal casts and a gradual spreading of the Cd distribution within the sediment column. When Cd was added to the entire sediment column, bioturbation caused a net transport of Cd upwards, resulting in the surface layers having higher Cd concentrations than the deeper layers, indicating a net release of Cd from deeper sediments. The distribution of Cd in lugworms depended on the Cd exposure situation and suggested that worms were exposed mainly to water-borne Cd when Cd was added to the top of the sediment, whereas worms were exposed mainly by ingesting Cd-labeled sediment when Cd was mixed homogeneously throughout the sediment.

  16. Suspended sediment concentration mapping based on the MODIS satellite imagery in the East China inland, estuarine, and coastal waters

    NASA Astrophysics Data System (ADS)

    Yang, Xianping; Sokoletsky, Leonid; Wei, Xiaodao; Shen, Fang

    2017-01-01

    The purpose of this research is to improve the retrieval accuracy for the suspended sediment concentration (SSC) from in situ and satellite remote sensing measurements in turbid East China estuarine and coastal waters. For this aim, three important tasks are formulated and solved: 1) an estimation of remote-sensing reflectance spectra R rs(λ) after atmospheric correction; 2) an estimation of R rs(λ) from the radiometric signals above the air-water surface; and 3) an estimation of SSC from R rs(λ). Six different models for radiometric R rs(λ) determination and 28 models for SSC versus R rs(λ) are analyzed based on the field observations made in the Changjiang River estuary and its adjacent coastal area. The SSC images based on the above-mentioned analysis are generated for the area.

  17. Persistence, temporal and spatial profiles of ultraviolet absorbents and phenolic personal care products in riverine and estuarine sediment of the Pearl River catchment, China.

    PubMed

    Peng, Xianzhi; Xiong, Songsong; Ou, Weihui; Wang, Zhifang; Tan, Jianhua; Jin, Jiabin; Tang, Caiming; Liu, Jun; Fan, Yujuan

    2017-02-05

    A variety of personal care products have been classified as emerging contaminants (ECs). Occurrence, fate, spatial and vertical profiles of 13 ultraviolet absorbents, triclocarban (TCC) and its dechlorinated products, triclosan (TCS), 2-phenylphenol and parabens were investigated in riverine and estuarine sediment of the Pearl River catchment, China. Bisphenol A (BPA), a widely applied plasticizer, was also investigated. The ECs were widely present in the bed sediment. TCC was the most abundant with a maximum concentration of 332ngg(-1) dry weight. The other prominent ECs included BPA, TCS, octocrylene, and benzotriazole UV stabilizers UV326 and UV328. Treated wastewater effluent was the major source of the ECs in the riverine sediment. TCC, BPA, TCS, methyparaben, UV531, UV326, and UV328 were also detected throughout the estuarine sediment cores, indicating their persistence in the sediment. Temporal trends of the ECs in the sediment cores reflected a combined effect of industrial development, population growth, human life quality improvement, and waste treatment capacity in the Pearl River Delta over the last decades. TCC dechlorination products were frequently detected in the bed sediment with higher levels near treated effluent outlets but only occasionally observed in the sediment cores, suggesting insignificant in-situ TCC dechlorination in the sediment.

  18. RELEASE AND PHASE PARTITIONING OF METALS FROM ANOXIC ESTUARINE SEDIMENTS DURING PERIODS OF SIMULATED RESUSPENSION

    EPA Science Inventory

    Periodically, marine sediments are subjected to physical processes which resuspend them into the water column, releasing previously sequestered metals. The role of resuspension energy and duration on release and subsequent redistribution of sediment bound metals was measured expe...

  19. Heavy metals in estuarine surface sediments of the Hai River Basin, variation characteristics, chemical speciation and ecological risk.

    PubMed

    Lei, Pei; Zhang, Hong; Shan, Baoqing; Lv, Shucong; Tang, Wenzhong

    2016-04-01

    The Hai River Basin (HRB) is considered to be one of the most polluted areas in China due to the high regional population density and rapid economic development. The estuaries of the HRB, which receive pollutants from terrestrial rivers, may subsequently suffer potential pollution and result in ecological risk of heavy metals. Six heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) were measured in estuarine surface sediments from 10 estuaries of the HRB to investigate their variation characteristics and ecological risks. The spatial difference of Cr, Ni, Pb, and Zn in sediments was higher than that of the rest two elements. The Yongdingxin Estuary (YDX) and Ziyaxin Estuary (ZYX) in the Northern Hai River System (NHRS) were the most severe in terms of heavy metal contamination. According to the Risk Assessment Code (RAC) classification, Cd associated with the exchangeable and carbonate fraction (the average of 21.3 %) indicated medium risk to high risk. More than 50 % of Cr, Cu, Ni, and Zn on average were associated with the residual fraction. Based on the sum of the first three fractions (exchangeable and carbonate + reducible + oxidizable), the mobility order of these heavy metals was Cd >Pb > Zn ≈ Cu > Ni > Cr. Compared to the background values of cinnamon soil, the potential ecological risk index (RI) values ranged from 25.6 to 168, with an average of 91.2, indicating a low ecological risk in estuarine sites of the HRB. Cd and Pb were the dominant contributors to the toxic-response factor (45.8 and 25.5 %, respectively). The results give insight into the different control measures pertaining to heavy metal pollution and risk for both relatively clean estuaries and urban seriously polluted areas, respectively, for the formation of protect strategies of aquatic environment in the HRB.

  20. Extractable organohalogens (EOX) in sediment and biota collected at an estuarine marsh near a former chloralkali facility

    SciTech Connect

    Kannan, K.; Giesy, J.P.; Kawano, Masahide; Kashima, Yuji; Matsui, Mitsuaki

    1999-04-01

    Extractable, organically bound chlorine (EOCl), which is determined by neutron activation analysis (NAA), has been used as a measure of pollution by chlorinated organics. In this study, the concentrations and distribution of extractable organohalogens (EOX = EOCl + EOBr + EOl) were measured in sediment, blue crab, fishes, birds, and terrapin collected at an estuarine marsh and a nearby creek contaminated by the disposal of wastes from a former chloralkali facility. The concentrations of the organohalogens were in the order of EOCl {much_gt} EOBr > EOl. The sediment EOCl concentration was comparable to those reported for sediments at sites that have been contaminated by the disposal of bleached kraft pulp mill effluents. The concentrations of EOCl measured in the tissues of blue crab, fishes, and birds were higher than any values previously reported. The absolute concentrations of EOCl coupled with its elevated proportions relative to the concentrations of EOBr or EOl in biota suggest that wastes from the chloralkali processes are a potential source of chlorinated organics present in the environment.

  1. Major factors influencing the elemental composition of surface estuarine sediments: the case of 15 estuaries in Portugal.

    PubMed

    Mil-Homens, M; Vale, C; Raimundo, J; Pereira, P; Brito, P; Caetano, M

    2014-07-15

    Upper sediments (0-5 cm) were sampled in 94 sites of water bodies of the fifteen Portuguese estuaries characterized by distinct settings of climate, topography and lithology, and marked by diverse anthropogenic pressures. Confined areas recognized as highly anthropogenic impacted, as well as areas dominated by erosion or frequently dredged were not sampled. Grain size, organic carbon (Corg), Al and trace elements (As, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn) were determined. Normalisation of trace element concentrations to Al and Corg, correlations between elements and Principal Component Analysis (PCA) allowed identifying elemental associations and the relevance of grain-size, lithology and anthropogenic inputs on sediment chemical composition. Whereas grain-size is the dominant effect for the majority of the studied estuaries, the southern estuaries Mira, Arade and Guadiana are dominated by specific lithologies of their river basins, and anthropogenic effects are identified in Ave, Leça, Tagus and Sado. This study emphasizes how baseline values of trace elements in sediments may vary within and among estuarine systems. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Distribution and effects of shallow gas on bulk estuarine sediment properties

    USGS Publications Warehouse

    Hill, J.M.; Halka, J.P.; Conkwright, R.; Koczot, K.; Coleman, S.

    1992-01-01

    Gas bubble are present in sediments covering approximately 30% of the main stem of Chesapeake Bay, with bubbles occurring at the sediment-water interface in 18% of the main stem sediments. This biogenic gas is found either in the sediments in the lower salinity reaches of the Bay, or confined to sediments which overline infilled palaeodrainage channels formed during the Wisconsinan low sea level stand (approximately 18 ka). Gas associated with the old drainage network does not correlate with present bathymetry or sedimentological patterns. Some differences between the gas-charged and gas-free sediments are: (1) gas-charged sediments have water contents 10-20% higher than comparable gas-free cores; (2) organic matter is better presented with depth in the gas-charged sediments (upwards of 60% more at one depth); (3 monosulphides are dominant sulphide mineral phase within the gas-charged sediments, comprising over 40% of the total sulphur. Within the gas-free sediments monosulphides are significant only near the sediment-water interface and rapidly become negligible with depth, and; (4) cores of gas-charged sediments are highly colour-banded due to preservation of sulphide mineral variations, while gas-free cores are diagenetically altered to pyrite. 

  3. Development and validation of an experimental life support system for assessing the effects of global climate change and environmental contamination on estuarine and coastal marine benthic communities.

    PubMed

    Coelho, Francisco J R C; Rocha, Rui J M; Pires, Ana C C; Ladeiro, Bruno; Castanheira, José M; Costa, Rodrigo; Almeida, Adelaide; Cunha, Angela; Lillebø, Ana Isabel; Ribeiro, Rui; Pereira, Ruth; Lopes, Isabel; Marques, Catarina; Moreira-Santos, Matilde; Calado, Ricardo; Cleary, Daniel F R; Gomes, Newton C M

    2013-08-01

    An experimental life support system (ELSS) was constructed to study the interactive effects of multiple stressors on coastal and estuarine benthic communities, specifically perturbations driven by global climate change and anthropogenic environmental contamination. The ELSS allows researchers to control salinity, pH, temperature, ultraviolet radiation (UVR), tidal rhythms and exposure to selected contaminants. Unlike most microcosms previously described, our system enables true independent replication (including randomization). In addition to this, it can be assembled using commercially available materials and equipment, thereby facilitating the replication of identical experimental setups in different geographical locations. Here, we validate the reproducibility and environmental quality of the system by comparing chemical and biological parameters recorded in our ELSS with those prevalent in the natural environment. Water, sediment microbial community and ragworm (the polychaete Hediste diversicolor) samples were obtained from four microcosms after 57 days of operation. In general, average concentrations of dissolved inorganic nutrients (NO3 (-) ; NH4 (+) and PO4 (-3) ) in the water column of the ELSS experimental control units were within the range of concentrations recorded in the natural environment. While some shifts in bacterial community composition were observed between in situ and ELSS sediment samples, the relative abundance of most metabolically active bacterial taxa appeared to be stable. In addition, ELSS operation did not significantly affect survival, oxidative stress and neurological biomarkers of the model organism Hediste diversicolor. The validation data indicate that this system can be used to assess independent or interactive effects of climate change and environmental contamination on benthic communities. Researchers will be able to simulate the effects of these stressors on processes driven by microbial communities, sediment and seawater

  4. Contrasting Effects of Two Burrowing Crabs ( Chasmagnathus granulata and Uca uruguayensis) on Sediment Composition and Transport in Estuarine Environments

    NASA Astrophysics Data System (ADS)

    Botto, F.; Iribarne, O.

    2000-08-01

    The burrowing crabs Chasmagnathus granulata and Uca uruguayensis are important bioturbators of intertidal flats in SW Atlantic estuaries reworking large amounts of sediment ( C. granulata 2234·6 g m -2day -1, U. uruguayenis 678·9 g m -2day -1) and influencing sediment quality and bedload transport. Their activities increase substrate penetrability. Organic matter and water content are higher in crab beds when compared with nearby areas without crabs. Burrows of U. uruguayensis are closed during high tide while burrows of C. granulata are always open effectively trapping clay and silt size particles rich in organic matter. This trapping of sediment enhances the effect of C. granulata in modifying sediment characteristics. Both species impact sediment erodability but have contrasting effects on sediment bedload transport. Daily bedload transport was lower inside C. granulata beds than outside, while it was higher in U. uruguayensis beds when compared with control areas. While C. granulata stabilizes the sediment by placing fine and cohesive sediment on the surface, U. uruguayensis disrupts the sediment by pelletizing it and making it more easily eroded. The contrasting activities of these two species may produce opposing and significant impacts on the structure of the benthic community because of their impact on sediment stability.

  5. Individual, population and community level effects of subtle anthropogenic contamination in estuarine meiobenthos.

    PubMed

    Rubal, Marcos; Guilhermino, Lúcia M; Medina, Matías H

    2009-10-01

    The study presented here searched for the level of taxonomic resolution required to detect the effects of low-level chronic pollution on estuarine meiobenthic communities. Meiofauna from two sites, with special attention to harpacticoid copepods, was analysed at different taxonomic levels of aggregation using uni- and multivariate methods. Adaptation processes that could buffer biodiversity disruptions were also considered through the analysis of fitness-related and tolerance traits in the harpacticoid copepod Paronychocamptus nanus. Results showed that uni- and multivariate analyses could be inadequate when assessing subtle anthropogenic contamination. Instead, the assessment of inter-population differences in tolerance to the main source of stress rises as a required procedure if potential effects of this type of contamination are being investigated. Specifically, a 96 h acute toxicity test performed with populations from the affected site appears as a faster and reliable general tool to assess impacts of low-level chronic pollution in estuaries.

  6. Development of a hybrid pollution index for heavy metals in marine and estuarine sediments.

    PubMed

    Brady, James P; Ayoko, Godwin A; Martens, Wayde N; Goonetilleke, Ashantha

    2015-05-01

    Heavy metal pollution of sediments is a growing concern in most parts of the world, and numerous studies focussed on identifying contaminated sediments by using a range of digestion methods and pollution indices to estimate sediment contamination have been described in the literature. The current work provides a critical review of the more commonly used sediment digestion methods and identifies that weak acid digestion is more likely to provide guidance on elements that are likely to be bioavailable than other traditional methods of digestion. This work also reviews common pollution indices and identifies the Nemerow Pollution Index as the most appropriate method for establishing overall sediment quality. Consequently, a modified Pollution Index that can lead to a more reliable understanding of whole sediment quality is proposed. This modified pollution index is then tested against a number of existing studies and demonstrated to give a reliable and rapid estimate of sediment contamination and quality.

  7. Effects of sediment bioturbation by the estuarine amphipod Corophium volutator on fluoranthene resuspension and transfer into the mussel (Mytilus edulis)

    SciTech Connect

    Ciarelli, S.; Straalen, N.M. van; Klap, V.A.; Wezel, A.P. van

    1999-02-01

    To better understand the effects of bioturbation on partitioning and availability of sediment-bound contaminants to infaunal amphipods and mussels, experiments were carried out with fluoranthene-spiked sediment. Treatments included different densities of the estuarine amphipod, Corophium volutator. Total suspended solids (TSS), particulate organic carbon/particulate organic matter (POC/POM) in overlying water, fluoranthene concentrations in sediment, pore water, overlying water, amphipods, and mussels were measured. Bioturbation significantly increased TSS and POC/POM concentrations in overlying water, and this effect became greater at higher animal density and longer exposure time. Mean total aqueous fluoranthene concentrations increased from 2.40 to 4.1 and 5.45 {micro}g/L in the control, low-density, and high-density treatments, respectively, after 10 d of exposure. The particle-bound fraction of fluoranthene in the overlying water from the high-density treatment was two times higher than that from the low-density treatment. Bioturbation did not affect the partitioning of fluoranthene over suspended solids and water, nor did it affect the concentrations in sediment and pore water. This was illustrated by the constancy of sediment-interstitial water partitioning coefficients (log K{sub oc(iw)}), sediment-overlying water partitioning coefficients (log K{sub oc(ow)}), and normalized POC-water partitioning coefficients (log K{sub poc}). Uptake of fluoranthene by filter-feeding mussels (Mytilus edulis) increased linearly with the density of bioturbating amphipods and with exposure time. The difference in concentrations of fluoranthene in mussels between the lowest and highest density of amphipods was more than factor of two. Their results showed that bioturbation significantly increases TSS concentration in the overlying water and consequently the total aqueous concentration of sediment-bound contaminants, which are subsequently accumulated by filter-feeders. The

  8. Evaluation of reduced sediment volume procedures for acute toxicity tests using the estuarine amphipod Leptocheirus plumulosus.

    PubMed

    Stanley, Jacob K; Kennedy, Alan J; Farrar, J Daniel; Mount, David R; Steevens, Jeffery A

    2010-12-01

    The volume of sediment required to perform a sediment toxicity bioassay is a major driver of the overall cost associated with that bioassay. Sediment volume affects bioassay cost because of sediment collection, transportation, storage, and disposal costs as well as labor costs associated with organism recovery at the conclusion of the exposure. The objective of the current study was to evaluate reduced sediment volume versions of the standard U.S. Environmental Protection Agency (U.S. EPA) 10-d acute Leptocheirus plumulosus method that uses a beaker size of 1,000 ml and 20 organisms. The test design used evaluated the effects of beaker size (250 and 100 ml) and associated sediment volume (75 and 30 ml, respectively) as well as organism loading density (10 and 20 organisms) on test endpoint responsiveness relative to the standard 10-d test method. These comparisons were completed with three different types of contaminated sediments: a field-collected polycyclic aromatic hydrocarbon (PAH)-contaminated sediment, a lead-spiked control sediment, and a control sediment spiked with mineral oil. Assessment criteria included test endpoint sensitivity, endpoint consistency, statistical power, water quality, and logistical assessments. Results indicate that the current U.S. EPA method is preferable to the reduced sediment volume methods we assessed, but that a 250-ml beaker/10 organism experimental design is of comparable utility and may be advantageous when reduced sediment volumes are desirable because of high contaminant (spiking studies) or sediment disposal costs. In addition, the results of the current study provide toxicity reference values for PAHs, lead, and an oil surrogate for petroleum hydrocarbons. Copyright © 2010 SETAC.

  9. Multi-level assessment of chronic toxicity of estuarine sediments with the amphipod Gammarus locusta: II. Organism and population-level endpoints.

    PubMed

    Costa, Filipe O; Neuparth, Teresa; Correia, Ana D; Costa, Maria Helena

    2005-07-01

    This study aimed to test the performance of the amphipod Gammarus locusta (L.) in chronic sediment toxicity tests. It constitutes part of a multi-level assessment of chronic toxicity of estuarine sediments, integrating organism and population-level endpoints with biochemical markers responses. Here we account for organism and population-level effects, while biomarker responses were reported in a companion article. Five moderately contaminated sediments from Sado and Tagus estuaries were tested, comprising 3 muddy and 2 sandy sediments. These sediments either did not show acute toxicity or were diluted with control sediment as much as required to remove acute toxicity. Subsequent chronic tests consisted of 28-day exposures with survival, individual growth and reproductive traits as endpoints. Two of the muddy sediments induced higher growth rates in the amphipods, and improved reproductive traits. This was understood to be a consequence of the amount of organic matter in the sediment, which was nutritionally beneficial to the amphipods, while concurrently decreasing contaminant bioavailability. Biomarker responses did not reveal toxicant-induced stress in amphipods exposed to these sediments. One of the sandy sediments was acutely toxic at 50% dilution, but in contrast stimulated amphipod growth when diluted 75%. This was presumed to be an indication of a hormetic response. Finally the two remaining contaminated sediments showed pronounced chronic toxicity, affecting survival and reproduction. The sex ratio of survivors was highly biased towards females, and offspring production was severely impaired. The particulars of the responses of this amphipod were examined, as well as strengths versus limitations of the sediment test. This study illustrates the utility of this chronic test for toxicity assessment of contaminated estuarine sediments, with potential application all along Atlantic Europe.

  10. Geochemical characterization of mangrove sediments of the Zuari estuarine system, West coast of India

    NASA Astrophysics Data System (ADS)

    Noronha-D'Mello, Cheryl A.; Nayak, G. N.

    2015-12-01

    The grain size, clay mineralogy and geochemistry were studied in the sediment cores collected from the mangrove environments of the Zuari estuary to understand sources and factors affecting accumulation, mobility, bioavailability and toxicity of metals. Finer sediments, organic matter and metals were higher in the middle estuary and canal sediments while coarser sediments with fewer metal concentrations were seen in the lower estuary. Kaolinite, smectite, illite and traces of chlorite constituted the clay mineral assemblage and had a minor influence on metal distributions. In the study area, the hydrodynamic conditions changed from lower estuary towards the upstream regions owing to mixing of riverine and sea water that led to finer sediment deposition in the middle estuary. The variations in metal abundance were attributed to a difference in hydrodynamic conditions regulated by the tide, freshwater flow and geomorphology of the Zuari estuary. The results revealed that the estuary received material from natural weathering of rocks as well as from anthropogenic sources such as mining and industrial/domestic discharges. Enrichment factor and Geo-accumulation index showed that Fe, Mn and Cr were enriched in the mangrove sediments whereas fractionation of metals revealed that concentrations of bioavailable Mn pose a considerable risk to biota. Increased accumulation of Fe and Mn in the upper middle estuary and canal sediments, trap trace metals that may considerably affect sediment quality and dredging of these sediments can cause re-suspension and mobilize metals from loosely bound sedimentary forms to the water column.

  11. Effects of sediment-associated phenanthrene and fluoranthene on offspring production, grazing and behavior of an estuarine copepod

    SciTech Connect

    Lotufo, G.R.

    1995-12-31

    Estuarine harpacticoids proved to be excellent toxicity-test organisms due to their ecological importance, small size, short generation time and high fecundity and sensitivity. One acute and three different sublethal sediment-tests were performed using laboratory-cultured Schizopera knabeni, an abundant mud-flat harpacticoid copepod common in US estuaries. All experiments were conducted in the dark and at constant temperature. The sediment TOC was 1.5%. The 96hLC{sub 50} was 524 mg/kg, for phenanthrene and > 2,000 mg/kg for fluoranthene. A strong narcotic effect was observed in the fluoranthene exposures, in which copepods survived exposures of up to 2,100 mg/kg. Effects on offspring production was assessed by exposing either individual mating pairs (male clasping an immature female) or a pool of 20 adult non-ovigerous females and 15 males for 14 days. A significant decrease in the total number of offspring (eggs + juveniles) produced was detected at concentrations as low as 30 mg/kg for both compounds. A stronger reduction was observed on the fraction of the offspring that attained later development stages (copepodite), suggesting that PAHs retard egg hatching and larval development. Effects on grazing activity were detected by feeding starved copepods with {sup 14}C radiolabeled diatoms. A significant decrease in grazing occurred at phenanthrene and fluoranthene concentrations much lower than the 96hLC{sub 50} after a contaminant exposure period of only 48 hours. Behavior experiments performed in an avoidance arena demonstrated that Schizopera displays the ability to detect the presence of PAH in sediment and avoids exposure by selecting and burrowing into uncontaminated over contaminated sediment. This is the first investigation of the effects of PAH single compounds on a meiofaunal organism.

  12. Occurrence and behavior of butyltins in intertidal and shallow subtidal surface sediments of an estuarine beach under different sampling conditions

    NASA Astrophysics Data System (ADS)

    Santos, Dayana Moscardi dos; Sant'Anna, Bruno Sampaio; Sandron, Daniela Corsino; Cardoso de Souza, Sara; Cristale, Joyce; Marchi, Mary Rosa Rodrigues de; Turra, Alexander

    2010-07-01

    Contamination by butyltin compounds (BTs) has been reported in estuarine environments worldwide, with serious impacts on the biota of these areas. Considering that BTs can be degraded by varying environmental conditions such as incident light and salinity, the short-term variations in such factors may lead to inaccurate estimates of BTs concentrations in nature. Therefore, the present study aimed to evaluate the possibility that measurements of BTs in estuarine sediments are influenced by different sampling conditions, including period of the day (day or night), tidal zone (intertidal or subtidal), and tides (high or low). The study area is located on the Brazilian southeastern coast, São Vicente Estuary, at Pescadores Beach, where BT contamination was previously detected. Three replicate samples of surface sediment were collected randomly in each combination of period of the day, tidal zone, and tide condition, from three subareas along the beach, totaling 72 samples. BTs were analyzed by GC-PFPD using a tin filter and a VF-5 column, by means of a validated method. The concentrations of tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) ranged from undetectable to 161 ng Sn g -1 (d.w.). In most samples (71%), only MBT was quantifiable, whereas TBTs were measured in only 14, suggesting either an old contamination or rapid degradation processes. DBT was found in 27 samples, but could be quantified in only one. MBT concentrations did not differ significantly with time of day, zones, or tide conditions. DBT and TBT could not be compared under all these environmental conditions, because only a few samples were above the quantification limit. Pooled samples of TBT did not reveal any difference between day and night. These results indicated that, in assessing contamination by butyltin compounds, surface-sediment samples can be collected in any environmental conditions. However, the wide variation of BTs concentrations in the study area, i.e., over a very small

  13. Estuarine fish communities respond to climate variability over both river and ocean basins.

    PubMed

    Feyrer, Frederick; Cloern, James E; Brown, Larry R; Fish, Maxfield A; Hieb, Kathryn A; Baxter, Randall D

    2015-10-01

    Estuaries are dynamic environments at the land-sea interface that are strongly affected by interannual climate variability. Ocean-atmosphere processes propagate into estuaries from the sea, and atmospheric processes over land propagate into estuaries from watersheds. We examined the effects of these two separate climate-driven processes on pelagic and demersal fish community structure along the salinity gradient in the San Francisco Estuary, California, USA. A 33-year data set (1980-2012) on pelagic and demersal fishes spanning the freshwater to marine regions of the estuary suggested the existence of five estuarine salinity fish guilds: limnetic (salinity = 0-1), oligohaline (salinity = 1-12), mesohaline (salinity = 6-19), polyhaline (salinity = 19-28), and euhaline (salinity = 29-32). Climatic effects propagating from the adjacent Pacific Ocean, indexed by the North Pacific Gyre Oscillation (NPGO), affected demersal and pelagic fish community structure in the euhaline and polyhaline guilds. Climatic effects propagating over land, indexed as freshwater outflow from the watershed (OUT), affected demersal and pelagic fish community structure in the oligohaline, mesohaline, polyhaline, and euhaline guilds. The effects of OUT propagated further down the estuary salinity gradient than the effects of NPGO that propagated up the estuary salinity gradient, exemplifying the role of variable freshwater outflow as an important driver of biotic communities in river-dominated estuaries. These results illustrate how unique sources of climate variability interact to drive biotic communities and, therefore, that climate change is likely to be an important driver in shaping the future trajectory of biotic communities in estuaries and other transitional habitats.

  14. Estuarine fish communities respond to climate variability over both river and ocean basins

    USGS Publications Warehouse

    Feyrer, Frederick V.; Cloern, James E.; Brown, Larry R.; Fish, Maxfield; Hieb, Kathryn; Baxter, Randall

    2015-01-01

    Estuaries are dynamic environments at the land–sea interface that are strongly affected by interannual climate variability. Ocean–atmosphere processes propagate into estuaries from the sea, and atmospheric processes over land propagate into estuaries from watersheds. We examined the effects of these two separate climate-driven processes on pelagic and demersal fish community structure along the salinity gradient in the San Francisco Estuary, California, USA. A 33-year data set (1980–2012) on pelagic and demersal fishes spanning the freshwater to marine regions of the estuary suggested the existence of five estuarine salinity fish guilds: limnetic (salinity = 0–1), oligohaline (salinity = 1–12), mesohaline (salinity = 6–19), polyhaline (salinity = 19–28), and euhaline (salinity = 29–32). Climatic effects propagating from the adjacent Pacific Ocean, indexed by the North Pacific Gyre Oscillation (NPGO), affected demersal and pelagic fish community structure in the euhaline and polyhaline guilds. Climatic effects propagating over land, indexed as freshwater outflow from the watershed (OUT), affected demersal and pelagic fish community structure in the oligohaline, mesohaline, polyhaline, and euhaline guilds. The effects of OUT propagated further down the estuary salinity gradient than the effects of NPGO that propagated up the estuary salinity gradient, exemplifying the role of variable freshwater outflow as an important driver of biotic communities in river-dominated estuaries. These results illustrate how unique sources of climate variability interact to drive biotic communities and, therefore, that climate change is likely to be an important driver in shaping the future trajectory of biotic communities in estuaries and other transitional habitats.

  15. Reduction of selenate to selenide by sulfate-respiring bacteria: Experiments with cell suspensions and estuarine sediments

    USGS Publications Warehouse

    Zehr, J.P.; Oremland, R.S.

    1987-01-01

    Washed cell suspension of Desulfovibrio desulfuricans subsp. aestuarii were capable of reducing nanomolar levels of selenate to selenide as well as sulfate to sulfide. Reduction of these species was inhibited by 1 mM selenate or tungstate. The addition of 1 mM sulfate decreased the reduction of selenate and enhanced the reduction of sulfate. Increasing concentrations of sulfate inhibited rates of selenate reduction but enhanced sulfate reduction rates. Cell suspensions kept in 1 mM selenate were incapable of reducing either selenate or sulfate when the selenate/sulfate ratio was ???0.02, indicating that irreversible inhibition occurs at high selenate concentrations. Anoxic estuarine sediments having an active flora of sulfate-respiring bacteria were capable of a small amount of selenate reduction when ambient sulfate concentrations were low (<4 mM). These results indicate that sulfate is an inhibitor of the reduction of trace qunatitites of selenate. Therefore, direct reduction of traces of selenate to selenide by sulfate-respiring bacteria in natural environments is constrained by the ambient concentration of sulfate ions. The significance of this observation with regard to the role sediments play in sequestering selenium is discussed

  16. Chemical versus Enzymatic Digestion of Contaminated Estuarine Sediment: Relative Importance of Iron and Manganese Oxides in Controlling Trace Metal Bioavailability

    NASA Astrophysics Data System (ADS)

    Turner, A.; Olsen, Y. S.

    2000-12-01

    Chemical and enzymatic reagents have been employed to determine available concentrations of Fe, Mn, Cu and Zn in contaminated estuarine sediment. Gastric and intestinal enzymes (pepsin, pH 2, and trypsin, pH 7·6, respectively) removed significantly more metal than was water-soluble or exchangeable (by seawater or ammonium acetate), while gastro-intestinal fluid of the demersal teleost, Pleuronectes platessa L. (plaice), employed to operationally define a bioavailable fraction of contaminants, generally solubilized more metal than the model enzymes. Manganese was considerably more available than Fe under these conditions and it is suggested that the principal mechanism of contaminant release is via surface complexation and reductive solubilization of Mn oxides, a process which is enhanced under conditions of low pH. Of the chemical reagents tested, acetic acid best represents the fraction of Mn (as well as Cu and Zn) which is available under gastro-intestinal conditions, suggesting that the reducing tendency of acetate is similar to that of the ligands encountered in the natural digestive environment. Although the precise enzymatic and non-enzymatic composition of plaice gastro-intestinal fluid may be different to that encountered in more representative, filter-feeding or burrowing organisms, a general implication of this study is that contaminants associated with Mn oxides are significantly more bioavailable than those associated with Fe oxides, and that contaminant bioavailability may be largely dictated by the oxidic composition of contaminated sediment.

  17. A Random Forest Approach to Predict the Spatial Distribution of Sediment Pollution in an Estuarine System

    EPA Science Inventory

    Modeling the magnitude and distribution of sediment-bound pollutants in estuaries is often limited by incomplete knowledge of the site and inadequate sample density. To address these modeling limitations, a decision-support tool framework was conceived that predicts sediment cont...

  18. Bioaccumulation of PAH by oysters (Crassostrea virginica) from estuarine sediments contaminated with petroleum hydrocarbons

    SciTech Connect

    McMillin, D.; Sarradet, K.; Means, J.

    1995-12-31

    Produced water discharges contain polycyclic aromatic hydrocarbons (PAH), typical of petroleum sources, which sorb to sediments and have been shown to accumulate to high levels in the sediments. Oysters were exposed to four dilutions, 0%, 6%, 12%, and 25%, of a sediment collected at Pass Fourchon, LA, a site severely impacted by long-term produced water discharges. Over a six year period concentrations of total PAH ranged from 14--60 ppm at this site. Alkylated PAH constituted around 92% of the total PAH measured in sediment collected 400 m from the actual discharge. Dilutions of the contaminated sediment were prepared using sediment from a nearby reference site, Lake Champagne. Following acclimation in the lab, oysters were exposed to the sediment dilutions for periods up to 28 days, with mortality recorded and alternate-day feeding and water changes. Depuration was measured in oysters removed to clean tanks for 10 days following 28-day exposure. The oysters from each tank were pooled, homogenized and analyzed for 62 individual parent, alkylated and heterocyclic PAH by GC/MS. Accumulation factors (AF) may be used to predict bioaccumulation using sediment characteristics.

  19. Biological Processes Affecting Bioaccumulation, Transfer, and Toxicity of Metal Contaminants in Estuarine Sediments

    DTIC Science & Technology

    2011-12-01

    to assess the bioavailability of metals from contaminated sediments to diverse suspension-feeding and deposit-feeding benthic bivalve molluscs . These...sediment-bound metals to marine bivalve molluscs : An overview. Estuaries 27, 826-838. Karimi, R., Chen, C.Y., Pickhardt, P.C., Fisher, N.S., Folt, C.L

  20. Associations between degraded benthic communities and contaminated sediments: Sabine Lake, Lake Pontchartrain, and Choctawhatchee Bay

    SciTech Connect

    Engle, V.D.; Summers, J.K.; Macauley, J.M.

    1994-12-31

    The Environmental Monitoring and Assessment Program for Estuaries (EMAP-E) in the Gulf of Mexico supplements its base sampling effort each year with localized, intensive spatial sampling in selected large estuarine systems. By selecting random locations within 70 km{sup 2} hexagonal areas, individual estuaries were sampled using EMAP methods but at four times the density as base sampling. In 1992, 19 sites were sampled in Lake Pontchartrain, Louisiana. In 1 993, 18 sites were sampled in Sabine Lake, Texas and 12 sites were sampled in Choctawhatchee Bay, Florida. At all sites, sediment grabs were taken and analyzed for benthic species composition and abundance, for toxicity to Ampelisca, and for organic and inorganic sediment contaminants. An indicator of biotic integrity, the benthic index, was calculated to represent the status of benthic communities. A series of statistical techniques, such as stepwise regression analysis, were employed to determine whether the variation in the benthic index could be associated with variation in sediment contaminants, sediment toxicity, or levels of dissolved oxygen. Spatial distributions of these parameters were examined to determine the geographical co-occurrence of degraded benthic communities and environmental stressors. In Lake Pontchartrain, for example, 85% of the variation in the benthic index was associated with decreased levels of dissolved oxygen, and increased concentrations of PCBs, alkanes, copper, tin, and zinc in the sediments.

  1. Estuarine and coastal water dynamics controlling sediment movement and plume development in Long Island Sound

    NASA Technical Reports Server (NTRS)

    Ruggles, F. H., Jr. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. As the Connecticut River flows into Long Island Sound, large plumes develop during the mixing of ocean and estuarine waters. Plumes were delineated for July 28, October 8, October 27, and December 2, 1972, by analyzing ERTS-1 imagery with the SRI Electronic Satellite Image Analysis Console (ESIAC). Because the chemical and physical composition of the plume and ocean water were not too different, the ESIAC was utilized to expand the scenes and subject the transparencies to varying combinations of viewing techniques to identify and delineate the plumes. Best results were obtained when band 5 transparencies were used. Indications are, when the scene being analyzed is predominantly in the first two steps of the gray scale, it is best to use the negative transparencies. When the analysis is being done above the first two steps of the gray scale, it is best to use the positive transparencies.

  2. Response of anaerobic ammonium oxidation to inorganic nitrogen fluctuations in temperate estuarine sediments

    NASA Astrophysics Data System (ADS)

    Teixeira, Catarina; Magalhães, Catarina; Joye, Samantha B.; Bordalo, Adriano A.

    2016-07-01

    The discovery of anaerobic ammonium oxidation (anammox) highlighted the importance of alternative metabolic pathways to inorganic nitrogen removal in natural environments, particularly in those subjected to increased nitrate inputs, such as estuaries. Laboratory enrichment experiments were used to test the effect of increasing loads of nitrate (NO3-), nitrite (NO2-), and ammonium (NH4+) on the anammox process. Three Atlantic temperate estuaries (NW Portugal) were investigated along a salinity gradient, and anammox activity was measured under different NO3-, NO2-, and NH4+ treatments, using the isotope pairing technique. Obtained results showed that NO3- stimulated denitrification but not anammox, whereas NO2- additions had a positive effect on anammox activity, confirming its role as a key environmental control. On the other hand, increasing NH4+ concentrations seemed to inhibit anammox for low salinity sites. Our findings suggested an important role of the natural availability of nitrogen compounds in regulating anammox and the magnitude of anammox versus denitrification in estuarine environments.

  3. Changes in estuarine sediment phosphorus fractions during a large-scale Mississippi River diversion.

    PubMed

    Roy, Eric D; Nguyen, Nhan T; White, John R

    2017-12-31

    Ongoing deterioration and loss of wetlands in the Mississippi River delta threatens the survival of Louisiana's coastal ecosystems and human settlements. In response, the State of Louisiana has proposed a $50 billion, 50-year restoration program. A central piece of this program is the reintroduction of Mississippi River water into the deltaic plain using managed diversions that mimic natural flood pulses. These diversions would transport critically needed sediment, but also deliver large nutrient loads. Coastal eutrophication is therefore a concern, particularly blooms of toxin-producing cyanobacteria. The Bonnet Carré Spillway (BCS) is an existing large flood diversion that protects New Orleans and provides an opportunity to investigate diversion nutrient transport. Here, we quantify sediment phosphorus (P) deposited by the BCS for the first time, and use a sequential P fractionation scheme to evaluate the likelihood of future sediment P release to the water column of the Lake Pontchartrain Estuary. In 2011, we collected sediment cores in the estuary for determination of P fractions before and after the discharge of 21.9km(3) of river water through the BCS in just under 6weeks. We observed the greatest net increases in sediment total P, inorganic P forms, and more labile organic P in the region near the inflow. We estimate that the diversion deposited ≥5000 metric tons of P in the sediments of the Lake Pontchartrain Estuary. The sum of readily available inorganic P, Fe/Al-bound inorganic P, and more labile organic P equaled approximately 20-30% of post-diversion sediment total P. These fractions are more likely to be released to the water column than the other sediment P forms we quantified. Diversion designs that encourage sedimentation in coastal marshes versus open bays can likely reduce the chances that deposited particulate P creates eutrophication risk. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Radiocarbon Dating, Chronologic Framework, and Changes in Accumulation Rates of Holocene Estuarine Sediments from Chesapeake Bay

    NASA Astrophysics Data System (ADS)

    Colman, Steven M.; Baucom, Pattie C.; Bratton, John F.; Cronin, Thomas M.; McGeehin, John P.; Willard, Debra; Zimmerman, Andrew R.; Vogt, Peter R.

    2002-01-01

    Rapidly accumulating Holocene sediments in estuaries commonly are difficult to sample and date. In Chesapeake Bay, we obtained sediment cores as much as 20 m in length and used numerous radiocarbon ages measured by accelerator mass spectrometry methods to provide the first detailed chronologies of Holocene sediment accumulation in the bay. Carbon in these sediments is a complex mixture of materials from a variety of sources. Analyses of different components of the sediments show that total organic carbon ages are largely unreliable, because much of the carbon (including coal) has been transported to the bay from upstream sources and is older than sediments in which it was deposited. Mollusk shells (clams, oysters) and foraminifera appear to give reliable results, although reworking and burrowing are potential problems. Analyses of museum specimens collected alive before atmospheric nuclear testing suggest that the standard reservoir correction for marine samples is appropriate for middle to lower Chesapeake Bay. The biogenic carbonate radiocarbon ages are compatible with 210Pb and 137Cs data and pollen stratigraphy from the same sites. Post-settlement changes in sediment transport and accumulation is an important environmental issue in many estuaries, including the Chesapeake. Our data show that large variations in sediment mass accumulation rates occur among sites. At shallow water sites, local factors seem to control changes in accumulation rates with time. Our two relatively deep-water sites in the axial channel of the bay have different long-term average accumulation rates, but the history of sediment accumulation at these sites appears to reflect overall conditions in the bay. Mass accumulation rates at the two deep-water sites rapidly increased by about fourfold coincident with widespread land clearance for agriculture in the Chesapeake watershed.

  5. Sensitivity of the sediment trapping capacity of an estuarine mangrove forest

    NASA Astrophysics Data System (ADS)

    Willemsen, P. W. J. M.; Horstman, E. M.; Borsje, B. W.; Friess, D. A.; Dohmen-Janssen, C. M.

    2016-11-01

    Intertidal mangrove forests exist in a dynamic coastal environment that is increasingly impacted by human interference, leading to habitat fragmentation, reduced habitat quality and changing hydrodynamic and geomorphological conditions. Biophysical feedback mechanisms are essential to maintain mangrove ecosystems under such changing conditions, for example by facilitating sediment deposition during periods of tidal flooding to allow for long-term coastal accretion. However, human interferences affect these biophysical interactions. This study investigated the consequences of two widespread anthropogenic intervention scenarios on biophysical interactions in mangroves: sediment starvation (reduced sediment supply) and coastal squeeze (limited landward accommodation space). Field observations of hydrodynamics and sediment dynamics were conducted in Mandai mangrove fringing the sheltered northern shore of Singapore. A process-based numerical model (Delft3D) of this field site was set-up, providing accurate approximations of the observed flow velocities and deposition rates. This model was used for a scenario analysis of the initial response of the sediment trapping capacity in the mangrove system to instantaneous changes related to anthropogenic interventions. This analysis showed increased deposition rates in major parts of the mangrove when sediment supplies increased (up to three times more deposition after 1 tide) or when the landward accommodation space of the mangrove was extended (+ 17% deposition). A comparison of the outcomes of these scenarios with the current state of the mangrove underlined a lack of short-term sediment trapping capacity, affecting the (longer-term) adaptive capacity of the system. Thus, at present Mandai mangrove is potentially affected by reduced sediment supply and limited landward accommodation space. Importantly, actions to reduce this anthropogenic influence could enhance mangroves' sediment trapping capacity, facilitating increased

  6. Radiocarbon dating, chronologic framework, and changes in accumulation rates of holocene estuarine sediments from Chesapeake Bay

    USGS Publications Warehouse

    Colman, Steven M.; Baucom, P.C.; Bratton, J.F.; Cronin, T. M.; McGeehin, J.P.; Willard, D.; Zimmerman, A.R.; Vogt, P.R.

    2002-01-01

    Rapidly accumulating Holocene sediments in estuaries commonly are difficult to sample and date. In Chesapeake Bay, we obtained sediment cores as much as 20 m in length and used numerous radiocarbon ages measured by accelarator mass spectrometry methods to provide the first detailed chronologies of Holocene sediment accumulation in the bay. Carbon in these sediments is a complex mixture of materials from a variety of sources. Analyses of different components of the sediments show that total organic carbon ages are largely unreliable, because much of the carbon (including coal) has been transported to the bay from upstream sources and is older than sediments in which it was deposited. Mollusk shells (clams, oysters) and foraminifera appear to give reliable results, although reworking and burrowing are potential problems. Analyses of museum specimens collected alive before atmospheric nuclear testing suggest that the standard reservoir correction for marine samples is appropriate for middle to lower Chesapeake Bay. The biogenic carbonate radiocarbon ages are compatible with 210 Pb and 137 Cs data and pollen stratigraphy from the same sites. Post-settlement changes in sediment transport and accumulation is an important environmental issue in many estuaries, including the Chesapeake. Our data show that large variations in sediment mass accumulation rates occur among sites. At shallow water sites, local factors seem to control changes in accumulation rates with time. Our two relatively deep-water sites in the axial channel of the bay have different long-term average accumulation rates, but the history of sediment accumulation at these sites appears to reflect overall conditions in the bay. Mass accumulation rates at the two deep-water sites rapidly increased by about fourfold coincident with widespread land clearance for agriculture in the Chesapeake watershed.

  7. Bacterial diversity, community structure and potential growth rates along an estuarine salinity gradient

    PubMed Central

    Campbell, Barbara J; Kirchman, David L

    2013-01-01

    Very little is known about growth rates of individual bacterial taxa and how they respond to environmental flux. Here, we characterized bacterial community diversity, structure and the relative abundance of 16S rRNA and 16S rRNA genes (rDNA) using pyrosequencing along the salinity gradient in the Delaware Bay. Indices of diversity, evenness, structure and growth rates of the surface bacterial community significantly varied along the transect, reflecting active mixing between the freshwater and marine ends of the estuary. There was no positive correlation between relative abundances of 16S rRNA and rDNA for the entire bacterial community, suggesting that abundance of bacteria does not necessarily reflect potential growth rate or activity. However, for almost half of the individual taxa, 16S rRNA positively correlated with rDNA, suggesting that activity did follow abundance in these cases. The positive relationship between 16S rRNA and rDNA was less in the whole water community than for free-living taxa, indicating that the two communities differed in activity. The 16S rRNA:rDNA ratios of some typically marine taxa reflected differences in light, nutrient concentrations and other environmental factors along the estuarine gradient. The ratios of individual freshwater taxa declined as salinity increased, whereas the 16S rRNA:rDNA ratios of only some typical marine bacteria increased as salinity increased. These data suggest that physical and other bottom-up factors differentially affect growth rates, but not necessarily abundance of individual taxa in this highly variable environment. PMID:22895159

  8. Maximum likelihood mixture estimation to determine metal background values in estuarine and coastal sediments within the European Water Framework Directive.

    PubMed

    Rodríguez, J G; Tueros, I; Borja, A; Belzunce, M J; Franco, J; Solaun, O; Valencia, V; Zuazo, A

    2006-11-01

    Some of the recently derived European Directives, such as the Water Framework and Marine Strategy, have, as ultimate aims, to achieve concentrations of hazardous substances in the marine environment near background values. Hence, the determination of natural background levels, in marine sediments, is highly relevant. The present study proposes the use of the maximum likelihood mixture estimation (MLME) to determine regional background levels and upper threshold of metal concentration, with the Basque Country as a case study (with a data set of 575 samples, from estuarine and littoral areas, including both intertidal and subtidal sediments). The heuristic procedure is applied with unimodal data distributions (Cd, Cr, Fe and Ni) and the mixture density estimations, based upon maximum likelihood, are carried out with polypopulational data distributions (As, Cu, Mn, Hg, Pb and Zn). The upper limits of the distribution are proposed, as the limits between 'High Status' and 'Good Status' (according to the Water Framework Directive terminology). The regional upper limits were 0.45 microg g(-1) for Cd, 71 microg g(-1) for Cr, 53,542 microg g(-1) for Fe, 57 microg g(-1) for Ni, 24 microg g(-1) for As, 64 microg g(-1) for Cu, 447 microg g(-1) for Mn, 0.27 microg g(-1) for Hg, 66 microg g(-1) for Pb, and 248 microg g(-1) for Zn. The results from this study can assist further in the determination of sediment reference conditions, to assess chemical status, within the above-mentioned directives; likewise, it will be studied as a useful methodology in determining regional metal backgrounds in other European countries.

  9. Variation in numbers and behaviour of waders during the tidal cycle: implications for the use of estuarine sediment flats

    NASA Astrophysics Data System (ADS)

    Granadeiro, José P.; Dias, Maria P.; Martins, Ricardo C.; Palmeirim, Jorge M.

    2006-05-01

    Estuarine sediment flats are essential feeding areas for waders, but their exploitation is constrained by the movements of tides. In this cyclic environment the exposure period of sediment flats decreases several fold from upper to lower flats, and the moving tidal waterline briefly creates particular conditions for waders and their prey. This study attempts to determine how the exposure period and the movement of the tide line influence the use of space and food resources by waders across the sediment flats. Wader counts and observations of feeding behaviour were carried out in all phases of the tidal cycle, in plots forming a transect from upper to lower flats, thus representing a gradient of exposure periods. Pecking, prey intake, and success rates varied little along the gradient. Some species actively followed the tide line while foraging, whereas others are evenly spread over the exposed flats. Black-tailed Godwit, Dunlin and Avocet were 'tide followers', whereas Grey Plover, Redshank and Bar-tailed Godwit were 'non-followers'. Densities of 'followers' near the tide line were up to five times higher than elsewhere. Species differed markedly in the way they used space on the flats, but in general the rate of biomass acquisition (in grams of ash-free dry weight per time exposed) was much higher in lower flats. However, this preference was insufficient to counter the much longer exposure of the upper flats, so the total amount of biomass consumed on the latter was greater. Therefore, it was in these upper flats that waders fulfilled most of their energetic needs. Consequently, upper flats are of particular importance for the conservation of wader assemblages, but because they are usually closer to shore they tend to suffer the highest pressure from disturbance and land reclamation.

  10. Ammonia-oxidizing bacterial community composition in estuarine and oceanic environments assessed using a functional gene microarray

    USGS Publications Warehouse

    Ward, B.B.; Eveillard, D.; Kirshtein, J.D.; Nelson, J.D.; Voytek, M.A.; Jackson, G.A.

    2007-01-01

    The relationship between environmental factors and functional gene diversity of ammonia-oxidizing bacteria (AOB) was investigated across a transect from the freshwater portions of the Chesapeake Bay and Choptank River out into the Sargasso Sea. Oligonucleotide probes (70-bp) designed to represent the diversity of ammonia monooxygenase (amoA) genes from Chesapeake Bay clone libraries and cultivated AOB were used to construct a glass slide microarray. Hybridization patterns among the probes in 14 samples along the transect showed clear variations in amoA community composition. Probes representing uncultivated members of the Nitrosospira-like AOB dominated the probe signal, especially in the more marine samples. Of the cultivated species, only Nitrosospira briensis was detected at appreciable levels. Discrimination analysis of hybridization signals detected two guilds. Guild 1 was dominated by the marine Nitrosospira-like probe signal, and Guild 2???s largest contribution was from upper bay (freshwater) sediment probes. Principal components analysis showed that Guild 1 was positively correlated with salinity, temperature and chlorophyll a concentration, while Guild 2 was positively correlated with concentrations of oxygen, dissolved organic carbon, and particulate nitrogen and carbon, suggesting that different amoA sequences represent organisms that occupy different ecological niches within the estuarine/marine environment. The trend from most diversity of AOB in the upper estuary towards dominance of a single type in the polyhaline region of the Bay is consistent with the declining importance of AOB with increasing salinity, and with the idea that AO-Archaea are the more important ammonia oxidizers in the ocean. ?? 2007 The Authors.

  11. A comparison of two nitrification inhibitors used to measure nitrification rates in estuarine sediments

    USGS Publications Warehouse

    Caffrey, J.M.; Miller, L.G.

    1995-01-01

    Nitrification rates were measured using intact sediment cores from South San Francisco Bay and two different nitrification inhibitors: acetylene and methyl fluoride. Sediment oxygen consumption and ammonium and nitrate fluxes were also measured in these cores. Four experiments were conducted in the spring, and one in the fall of 1993. There was no significant difference in nitrification rates measured using the two inhibitors, which suggests that methyl fluoride can be used as an effective inhibitor of nitrification. Nitrification was positively correlated with sediment oxygen consumption and numbers of macrofauna. This suggests that bioturbation by macrofauna is an important control of nitrification rates. Irrigation by the tube-dwelling polychaete, Asychis elongata, which dominates the benthic biomass at this location, appears particularly important. Ammonium fluxes out of the sediment were greatest about one week after the spring bloom, while nitrification peaked about one month later.

  12. Development of Reduced Sediment Volume Test Procedures for the Estuarine Amphipod Leptocheirus plumulosus

    EPA Science Inventory

    The sediment volume requirements of toxicity and bioaccumulation bioassays affect the cost of the assessment related to field collection, transportation, storage, disposal, and labor associated with organism recovery at bioassay termination. Our objective was to assess four redu...

  13. Development of Reduced Sediment Volume Test Procedures for the Estuarine Amphipod Leptocheirus plumulosus

    EPA Science Inventory

    The sediment volume requirements of toxicity and bioaccumulation bioassays affect the cost of the assessment related to field collection, transportation, storage, disposal, and labor associated with organism recovery at bioassay termination. Our objective was to assess four redu...

  14. Sediment quality assessment and Toxicity Identification Evaluation studies in Lavaca Bay, Texas -- An estuarine Superfund site

    SciTech Connect

    Carr, R.S.; Biedenbach, J.; Hooten, R.; May, L.; Teas, T.

    1995-12-31

    A sediment quality assessment survey was conducted in the Lavaca Bay system which has been designated a Superfund site because of elevated concentrations of mercury and other contaminants (e.g., PAHs) in the sediments. Twenty-four stations were sampled in the initial survey. Sediment pore water was extracted pneumatically and the toxicity of the pore water determined using the sea urchin fertilization and embryological development assays. Based on the results of the toxicity tests, aliquots of the toxic sediments were analyzed for metals, PAHs, and pesticides. Based on these results, several of the most toxic sites were resampled and a preliminary Toxicity Identification Evaluation (TIE) was performed with the pore water using the sea urchin fertilization test. Preliminary results indicated that the toxic components were removed by adsorption on a C-18 column but were not affected by EDTA additions and, therefore, the primary toxicants are hydrophobic in nature.

  15. Nitrate Reduction Functional Genes and Nitrate Reduction Potentials Persist in Deeper Estuarine Sediments. Why?

    PubMed Central

    Papaspyrou, Sokratis; Smith, Cindy J.; Dong, Liang F.; Whitby, Corinne; Dumbrell, Alex J.; Nedwell, David B.

    2014-01-01

    Denitrification and dissimilatory nitrate reduction to ammonium (DNRA) are processes occurring simultaneously under oxygen-limited or anaerobic conditions, where both compete for nitrate and organic carbon. Despite their ecological importance, there has been little investigation of how denitrification and DNRA potentials and related functional genes vary vertically with sediment depth. Nitrate reduction potentials measured in sediment depth profiles along the Colne estuary were in the upper range of nitrate reduction rates reported from other sediments and showed the existence of strong decreasing trends both with increasing depth and along the estuary. Denitrification potential decreased along the estuary, decreasing more rapidly with depth towards the estuary mouth. In contrast, DNRA potential increased along the estuary. Significant decreases in copy numbers of 16S rRNA and nitrate reducing genes were observed along the estuary and from surface to deeper sediments. Both metabolic potentials and functional genes persisted at sediment depths where porewater nitrate was absent. Transport of nitrate by bioturbation, based on macrofauna distributions, could only account for the upper 10 cm depth of sediment. A several fold higher combined freeze-lysable KCl-extractable nitrate pool compared to porewater nitrate was detected. We hypothesised that his could be attributed to intracellular nitrate pools from nitrate accumulating microorganisms like Thioploca or Beggiatoa. However, pyrosequencing analysis did not detect any such organisms, leaving other bacteria, microbenthic algae, or foraminiferans which have also been shown to accumulate nitrate, as possible candidates. The importance and bioavailability of a KCl-extractable nitrate sediment pool remains to be tested. The significant variation in the vertical pattern and abundance of the various nitrate reducing genes phylotypes reasonably suggests differences in their activity throughout the sediment column. This

  16. Potency and characterization of estrogen-receptor agonists in United Kingdom estuarine sediments.

    PubMed

    Thomas, Kevin V; Balaam, Jan; Hurst, Mark; Nedyalkova, Zoya; Mekenyan, Ovanes

    2004-02-01

    The activity of estrogen-receptor (ER) agonists in sediments collected from the United Kingdom (UK) estuaries was assessed using the in vitro recombinant yeast estrogen screen (YES assay). The YES assay was successfully used to determine the in vitro ER agonist potency of pore waters and solvent extracts of sediments collected from UK estuaries. Estrogen-receptor agonists were detected in 66% of the pore water samples and in 91% of the sediment solvent extracts tested. The pore waters tested had ER agonist potencies from less than 2 to 68 ng 17beta-estradiol (E2) L(-1), whereas sediment extracts had potencies from less than 0.2 to 13 microg E2 kg(-1). A toxicity identification evaluation approach using bioassay-directed fractionation was used in an attempt to identify the ER agonists in extracts of sediments collected from the Tyne and Tees estuaries (UK). Gas chromatography-mass spectrometry was used to provide lists of compounds in the fractions obtained that were evaluated for known ER agonist activity using published data and an ER quantitative structure-activity relationship model. Toxicity identification evaluation characterization failed to identify any ER agonists in pore water extracts; however, three compounds in sediment solvent extracts were identified as ER agonists. Nonylphenol, cinnarizine, and cholesta-4,6-dien-3-one were identified in the sample collected from the Tyne estuary. Important ER agonist substances that contaminate marine sediments remain unidentified. The present study as well as previous work on effluents point toward the involvement of natural products in the estrogenic burdens of marine sediments. Further work is required to establish the relative contribution of natural products and anthropogenic chemicals to current environmental impacts in the context of the Oslo and Paris Commission strategy to eliminate hazardous substances by 2020.

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

    USGS Publications Warehouse

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

    1974-01-01

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

  18. Factors affecting the bacterial community composition and heterotrophic production of Columbia River estuarine turbidity maxima.

    PubMed

    Herfort, Lydie; Crump, Byron C; Fortunato, Caroline S; McCue, Lee Ann; Campbell, Victoria; Simon, Holly M; Baptista, António M; Zuber, Peter

    2017-08-06

    Estuarine turbidity maxima (ETM) function as hotspots of microbial activity and diversity in estuaries, yet, little is known about the temporal and spatial variability in ETM bacterial community composition. To determine which environmental factors affect ETM bacterial populations in the Columbia River estuary, we analyzed ETM bacterial community composition (Sanger sequencing and amplicon pyrosequencing of 16S rRNA gene) and bulk heterotrophic production ((3) H-leucine incorporation rates). We collected water 20 times to cover five ETM events and obtained 42 samples characterized by different salinities, turbidities, seasons, coastal regimes (upwelling vs. downwelling), locations, and particle size. Spring and summer populations were distinct. All May samples had similar bacterial community composition despite having different salinities (1-24 PSU), but summer non-ETM bacteria separated into marine, freshwater, and brackish assemblages. Summer ETM bacterial communities varied depending on coastal upwelling or downwelling conditions and on the sampling site location with respect to tidal intrusion during the previous neap tide. In contrast to ETM, whole (>0.2 μm) and free-living (0.2-3 μm) assemblages of non-ETM waters were similar to each other, indicating that particle-attached (>3 μm) non-ETM bacteria do not develop a distinct community. Brackish water type (ETM or non-ETM) is thus a major factor affecting particle-attached bacterial communities. Heterotrophic production was higher in particle-attached than free-living fractions in all brackish waters collected throughout the water column during the rise to decline of turbidity through an ETM event (i.e., ETM-impacted waters). However, free-living communities showed higher productivity prior to or after an ETM event (i.e., non-ETM-impacted waters). This study has thus found that Columbia River ETM bacterial communities vary based on seasons, salinity, sampling location, and particle size, with the

  19. Suspended sediment transport in an estuarine tidal channel within San Francisco Bay, California

    USGS Publications Warehouse

    Sternberg, R.W.; Cacchione, D.A.; Drake, D.E.; Kranck, K.

    1986-01-01

    Size distributions of the suspended sediment samples, estimates of particle settling velocity (??s), friction velocity (U*), and reference concentration (Ca) at z = 20 cm were used in the suspended sediment distribution equations to evaluate their ability to predict the observed suspended sediment profiles. Three suspended sediment particle conditions were evaluated: (1) individual particle sizes in the 4-11 ?? (62.5-0.5 ??m) size range with the reference concentration Ca at z = 20 cm (C??); (2) individual particle sizes in the 4-6 ?? size range, flocs representing the 7-11 ?? size range with the reference concentration Ca at z = 20 cm (Cf); and (3) individual particle sizes in the 4-6 ?? size range, flocs representing the 7-11 ?? size range with the reference concentration predicted as a function of the bed sediment size distribution and the square of the excess shear stress. An analysis was also carried out on the sensitivity of the suspended sediment distribution equation to deviations in the primary variables ??s, U*, and Ca. In addition, computations of mass flux were made in order to show vertical variations in mass flux for varying flow conditions. ?? 1986.

  20. Molecular approaches to the investigation of viable dinoflagellate cysts in natural sediments from estuarine environments.

    PubMed

    Coyne, Kathryn J; Craig Cary, S

    2005-01-01

    Molecular methods offer an efficient alternative to microscopic identification of dinoflagellate cysts in natural sediments. Unfortunately, amplification of DNA also detects the presence of dead cells and is not a reliable indication of cyst viability. Because mRNA transcripts are more labile than DNA, the presence of specific transcripts may be used as a proxy for cyst viability. Here, we evaluate mRNA detection capabilities for identification of viable cysts of the dinoflagellate, Pfiesteria piscicida, in natural sediment samples. We targeted transcripts for cytochrome c oxidase subunit 1, cytochrome b (COB), and Tags 343 and 277, recently identified by serial analysis of gene expression. Expression was confirmed in laboratory cultures and compared with natural sediment samples. Three of the transcripts were detected in sediments by RT-PCR. The fourth transcript, for COB, was not detected in sediments, perhaps because of down-regulation of the gene in anoxic conditions. Our results suggest that methods targeting specific mRNA transcripts may be useful for detection of viable cysts in natural sediment samples. In addition, dinoflagellate cysts, which sustain extended periods of anoxia, may provide an important source of data for studies of anoxia tolerance by microbial eukaryotes.

  1. Estuarine Sediment Deposition during Wetland Restoration: A GIS and Remote Sensing Modeling Approach

    NASA Technical Reports Server (NTRS)

    Newcomer, Michelle; Kuss, Amber; Kentron, Tyler; Remar, Alex; Choksi, Vivek; Skiles, J. W.

    2011-01-01

    Restoration of the industrial salt flats in the San Francisco Bay, California is an ongoing wetland rehabilitation project. Remote sensing maps of suspended sediment concentration, and other GIS predictor variables were used to model sediment deposition within these recently restored ponds. Suspended sediment concentrations were calibrated to reflectance values from Landsat TM 5 and ASTER using three statistical techniques -- linear regression, multivariate regression, and an Artificial Neural Network (ANN), to map suspended sediment concentrations. Multivariate and ANN regressions using ASTER proved to be the most accurate methods, yielding r2 values of 0.88 and 0.87, respectively. Predictor variables such as sediment grain size and tidal frequency were used in the Marsh Sedimentation (MARSED) model for predicting deposition rates for three years. MARSED results for a fully restored pond show a root mean square deviation (RMSD) of 66.8 mm (<1) between modeled and field observations. This model was further applied to a pond breached in November 2010 and indicated that the recently breached pond will reach equilibrium levels after 60 months of tidal inundation.

  2. Suspended-sediment trapping in the tidal reach of an estuarine tributary channel

    USGS Publications Warehouse

    Downing-Kunz, Maureen; Schoellhamer, David H.

    2015-01-01

    Evidence of decreasing sediment supply to estuaries and coastal oceans worldwide illustrates the need for accurate and updated estimates. In the San Francisco Estuary (Estuary), recent research suggests a decrease in supply from its largest tributaries, implying the increasing role of smaller, local tributaries in sediment supply to this estuary. Common techniques for estimating supply from tributaries are based on gages located above head of tide, which do not account for trapping processes within the tidal reach. We investigated the effect of a tidal reach on suspended-sediment discharge for Corte Madera Creek, a small tributary of the Estuary. Discharge of water (Q) and suspended-sediment (SSD) were observed for 3 years at two locations along the creek: upstream of tidal influence and at the mouth. Comparison of upstream and mouth gages showed nearly 50 % trapping of upstream SSD input within the tidal reach over this period. At the storm time scale, suspended-sediment trapping efficiency varied greatly (range −31 to 93 %); storms were classified as low- or high-yield based on upstream SSD. As upstream peak Q increased, high-yield storms exhibited significantly decreased trapping. Tidal conditions at the mouth—ebb duration and peak ebb velocity—during storms had a minor effect on sediment trapping, suggesting fluvial processes dominate. Comparison of characteristic fluvial and tidal discharges at the storm time scale demonstrated longitudinal differences in the regulating process for SSD. These results suggest that SSD from gages situated above head of tide overestimate sediment supply to the open waters beyond tributary mouths and thus trapping processes within the tidal reach should be considered.

  3. Widespread Distribution of Dehalococcoides mccartyi in the Houston Ship Channel and Galveston Bay, Texas, Sediments and the Potential for Reductive Dechlorination of PCDD/F in an Estuarine Environment.

    PubMed

    Hieke, Anne-Sophie Charlotte; Brinkmeyer, Robin; Yeager, Kevin M; Schindler, Kimberly; Zhang, Saijin; Xu, Chen; Louchouarn, Patrick; Santschi, Peter H

    2016-12-01

    Sediments in the Houston Ship Channel and upper Galveston Bay, Texas, USA, are polluted with polychlorinated dibenzo-p-dioxins/furans (PCDD/F; ≤46,000 ng/kg dry weight (wt.)) with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic congener, contributing >50 % of the total toxic equivalents (TEQ) at most locations. We measured PCDD/F concentrations in sediments and evaluated the potential for enhanced in situ biodegradation by surveying for Dehalococcoides mccartyi, an obligate organohalide respiring bacterium. Dehalococcoides spp. (98 % similar to D. mccartyi) and 22 other members of the class Dehalococcoidia were predominant 16S ribosomal RNA (rRNA) phylotypes. Dehalococcoides spp. were also present in the active fraction of the bacterial community. Presence/absence PCR screening detected D. mccartyi in sediment cores and sediment grab samples having at least 1 ng/kg dry wt. TEQ at salinities ranging from 0.6 to 19.5 PSU, indicating that they are widespread in the estuarine environment. Organic carbon-only and organic carbon + sulfate-amended sediment microcosm experiments resulted in ∼60 % reduction of ambient 2,3,7,8-TCDD in just 24 months leading to reductions in total TEQs by 38.4 and 45.0 %, respectively, indicating that 2,3,7,8-TCDD degradation is occurring at appreciable rates.

  4. SPECIES-ABUNDANCE-BIOMASS RESPONSES BY ESTUARINE MACROBENTHOS TO SEDIMENT CHEMICAL CONTAMINATION.

    EPA Science Inventory

    Macrobenthic community responses can be measured through concerted changes in univariate metrics, including species richness, total abundance, and total biomass. The classic model of pollution effects on marine macroinvertebrate communities recognizes that species/abundance/bioma...

  5. SPECIES-ABUNDANCE-BIOMASS RESPONSES BY ESTUARINE MACROBENTHOS TO SEDIMENT CHEMICAL CONTAMINATION.

    EPA Science Inventory

    Macrobenthic community responses can be measured through concerted changes in univariate metrics, including species richness, total abundance, and total biomass. The classic model of pollution effects on marine macroinvertebrate communities recognizes that species/abundance/bioma...

  6. Estuarine sediment transport by gravity-driven movement of the nepheloid layer, Long Island Sound

    NASA Astrophysics Data System (ADS)

    Poppe, L. J.; McMullen, K. Y.; Williams, S. J.; Crocker, J. M.; Doran, E. F.

    2008-08-01

    Interpretation of sidescan-sonar imagery provides evidence that down-slope gravity-driven movement of the nepheloid layer constitutes an important mode of transporting sediment into the basins of north-central Long Island Sound, a major US East Coast estuary. In the Western Basin, this transport mechanism has formed dendritic drainage systems characterized by branching patterns of low backscatter on the seafloor that exceed 7.4 km in length and progressively widen down-slope, reaching widths of over 0.6 km at their southern distal ends. Although much smaller, dendritic patterns of similar morphology are also present in the northwestern part of the Central Basin. Because many contaminants display affinities for adsorption onto fine-grained sediments, and because the Sound is affected by seasonal hypoxia, mechanisms and dispersal pathways by which inorganic and organic sediments are remobilized and transported impact the eventual fate of the contaminants and environmental health of the estuary.

  7. Estuarine sediment transport by gravity-driven movement of the nepheloid layer, Long Island Sound

    USGS Publications Warehouse

    Poppe, L.J.; McMullen, K.Y.; Williams, S.J.; Crocker, J.M.; Doran, E.F.

    2008-01-01

    Interpretation of sidescan-sonar imagery provides evidence that down-slope gravity-driven movement of the nepheloid layer constitutes an important mode of transporting sediment into the basins of north-central Long Island Sound, a major US East Coast estuary. In the Western Basin, this transport mechanism has formed dendritic drainage systems characterized by branching patterns of low backscatter on the seafloor that exceed 7.4 km in length and progressively widen down-slope, reaching widths of over 0.6 km at their southern distal ends. Although much smaller, dendritic patterns of similar morphology are also present in the northwestern part of the Central Basin. Because many contaminants display affinities for adsorption onto fine-grained sediments, and because the Sound is affected by seasonal hypoxia, mechanisms and dispersal pathways by which inorganic and organic sediments are remobilized and transported impact the eventual fate of the contaminants and environmental health of the estuary. ?? Springer-Verlag 2008.

  8. Sedimentation: Potential Biological Effects of Dredging Operations in Estuarine and Marine Environments

    DTIC Science & Technology

    2005-05-01

    1999). “Impacts of sediment burial on mangroves.” Marine Pollution Bulletin 37, 420-426. Fonseca, M. S., Kenworthy, W. J., and Thayer, G W. (1998... Marine Pollution Bulletin 4, 166-169. Tomasko, D.A., Dawes, C. J., and Hall, M. O. (1996). “The effects of anthropogenic nutrient enrichment in...adjacent coral reefs,” Marine Pollution Bulletin 42, 864-872. Wilber, D. H., and Clarke, D. G. (2001). “Biological effects of suspended sediments: a

  9. Distribution and origins of polycyclic aromatic hydrocarbons (PAHs) in riverine, estuarine, and marine sediments in Thailand.

    PubMed

    Boonyatumanond, Ruchaya; Wattayakorn, Gullaya; Togo, Ayako; Takada, Hideshige

    2006-08-01

    To assess the status of polycyclic aromatic hydrocarbon (PAH) contamination in coastal and riverine environments in Thailand, we collected 42 surface sediment samples from canals, a river, an estuary, and coastal areas in Thailand in 2003 and analyzed them for PAHs with 3-7 benzene rings by gas chromatography-mass spectrometry (GC-MS). The total concentration of PAHs ranged from 6 to 8399 ng/g dry weight. The average total PAH concentrations were 2290+/-2556 ng/g dry weight (n=8) in canals, 263+/-174 (n=11) in the river, 179+/-222 (n=9) in the estuary, and 50+/-56 (n=14) in coastal areas. Comparison of the concentration range with a worldwide survey of sedimentary PAH concentrations ranked PAH contamination in Thai sediments as low to moderate. The ratio of the sum of methylphenanthrenes to phenanthrene (MP/P ratio) allows discrimination of PAH sources between petrogenic (>2) and pyrogenic (<0.5) origins. Sediments from urban canals in Bangkok showed the highest PAH concentrations and petrogenic signatures (MP/P=1.84+/-0.98 [n=6] in canal sediments) with abundant alkylated PAHs, indicating major sources of petrogenic PAHs in the city. To identify the sources of the petrogenic inputs in Thailand, we analyzed triterpanes, biomarkers of petroleum pollution, in the sediment samples and in potential source materials. Hopane profiles were remarkably uniform throughout the nation, suggesting a diffuse single source (e.g. automobiles). Molecular profiles of hopanes and PAHs in sediments from the urban canals were similar to those in street dust, indicating that street dust is one of the major sources of petrogenic PAHs in the urban area. On the other hand, low levels of PAHs (approximately 50 ng/g) with a pyrogenic signature (MP/P ratio approximately 0.5) were widely recorded in remote areas of the coast and the Chao Phraya River. These pyrogenic PAHs may be atmospherically transported throughout the nation. Middle and lower reaches of the Chao Phraya River, the river

  10. Geochemical and ecotoxicological assessment for estuarine surface sediments from Southern Brazil.

    PubMed

    Rodrigues, Sarah K; Abessa, Denis M S; Machado, Eunice C

    2013-10-01

    Sediments from Guaratuba Bay (PR, Brazil), a marine protected area, were collected and evaluated for geochemistry and toxicity. High levels of P and acute toxicity were observed in some samples. Concentrations of Cu, Cd, Pb and Zn were relatively low; however, Cd levels eventually exceeded Threshold Effect Level. Toxicities were associated to nutrients and metals enrichment. Results suggest that impacts are incipient and occur only at specific sites, associated to multiple contamination sources. Despite sediments quality seems to range between good and fair, attention is required to land-use planning around Guaratuba Bay and controlling local pollution sources. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Quantification of Sterol and Triterpenol Biomarkers in Sediments of the Cananéia-Iguape Estuarine-Lagoonal System (Brazil) by UHPLC-MS/MS

    PubMed Central

    Bataglion, Giovana Anceski; Koolen, Hector Henrique Ferreira; Weber, Rolf Roland; Eberlin, Marcos Nogueira

    2016-01-01

    Sterols and triterpenols present in sedimentary cores from 12 stations along the Cananéia-Iguape estuarine-lagoonal system were investigated by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Ten sterols and three triterpenols were identified and quantified, indicating both natural and anthropogenic sources. The relative distributions of sterol and triterpenol showed that the study area is submitted to organic matter (OM) from the Ribeira de Iguape River, seawater, surrounding vegetation, and plankton production. The contribution of these sources depends on the region of the estuarine-lagoonal system and the depth of sediment. Regarding anthropogenic sources, only the samples submitted to freshwater flow from the Ribeira de Iguape River presented concentration of coprostanol higher than the threshold value and diagnostic ratios, coprostanol/(coprostanol + cholestanol) and coprostanol/cholesterol, that indicate moderate contamination by domestic sewage in that area of the estuarine-lagoonal system. Therefore, the approach used herein identified the OM sources and its transport along the Cananéia-Iguape estuarine-lagoonal system (Brazil), which is a complex of lagoonal channels located in a United Nations Educational, Scientific and Cultural Organization (UNESCO) Biosphere Reserve. PMID:27087811

  12. Distribution, sources and ecological risk of polycyclic aromatic hydrocarbons in the estuarine-coastal sediments in the East China Sea.

    PubMed

    Li, Ye; Liu, Xinran; Liu, Min; Li, Xiaofei; Wang, Qing; Zhu, Junmin; Qadeer, Abdul

    2017-03-14

    Polycyclic aromatic hydrocarbons (PAHs), total organic carbon (TOC) and black carbon (BC) in the estuarine-coastal areas of the East China Sea (ECS) were investigated. The results showed that ∑PAH concentrations ranged from 61 to 355 ng g(-1) with a mean value of 146 ng g(-1). The contents of TOC and BC were in the range of 1.31-7.23 mg g(-1) and 0.52-5.60 mg g(-1), respectively. Data analyses showed that PAH concentrations had a positive linear relationship with TOC and with BC. In addition, the grain size of silts and clays had significant influence on the PAHs of sediments. These physicochemical properties as well as coastal currents, especially the trapping effect of the Taiwan Warm Current and the Zhejiang Fujian Coastal Current, played important roles in determining the spatial distribution of PAHs in the ECS. The estimated deposition flux of PAHs was 106 t per year in the study area. Source apportionment showed that these PAHs mainly originated from oil sources, and the combustion of liquid fossils and coal/wood.

  13. USE OF ULVA LACTUTA TO IDENTIFY AMMONIA TOXICITY IN MARINE AND ESTUARINE SEDIMENTS

    EPA Science Inventory

    Toxicity identification evaluation(TIE) methods are being developed for use with whole sediments. Although a phase I TIE method has been developed to characterize ammonia toxicity in aqueous samples using the marine macroalga Ulva lactuca, the relationship between amphipod and my...

  14. Interactions between waves, sediment, and turbulence on a shallow estuarine mudflat

    USGS Publications Warehouse

    MacVean, Lissa J.; Lacy, Jessica R.

    2014-01-01

    stress, which diffused sediment upward and limited stratification. Our findings highlight a pathway for waves to supply energy to both the production and destruction of turbulence, and demonstrate that in such shallow depths, TKE and SSC can be elevated over more of the water column than predicted by traditional models.

  15. Corrosion and fate of depleted uranium penetrators under progressively anaerobic conditions in estuarine sediment.

    PubMed

    Handley-Sidhu, Stephanie; Worsfold, Paul J; Boothman, Christopher; Lloyd, Jonathan R; Alvarez, Rebeca; Livens, Francis R; Vaughan, David J; Keith-Roach, Miranda J

    2009-01-15

    The testing of armor-piercing depleted uranium (DU) "penetrators" has resulted in the deposition of DU in the sediments of the Solway Firth, UK. In this study, DU-amended, microcosm experiments simulating Solway Firth sediments under high (31.5) and medium (16.5) salinity conditions were used to investigate the effect of salinity and biogeochemical conditions on the corrosion and fate of DU, and the impact of the corroding DU on the microbial population. Under suboxic conditions, the average corrosion rates were the same forthe 31.5 and 16.5 salinity systems at 0.056 +/- 0.006 g cm(-2) y(-1), implying that complete corrosion of a 120 mm penetrator would take approximately 540 years. Under sulfate-reducing conditions, corrosion ceased due to passivation of the surface. Corroding DU resulted in more reducing conditions and decreased microbial diversity as indicated by DNA sequencing and phylogenetic analysis. The lack of colloidal and particulate DU corrosion products, along with measurable dissolved U and a homogeneous association of U with the sediment, suggest that U was transported from the penetrator surface into the surrounding environment through dissolution of U(VI), with subsequent interactions resulting in the formation of secondary uranium species in the sediment.

  16. Effects of zinc pyrithione and copper pyrithione on microbial community function and structure in sediments.

    PubMed

    Groth Petersen, Dorthe; Dahllof, Ingela; Nielsen, Lars Peter

    2004-04-01

    The effects of the new antifouling biocides, zinc pyrithione (ZPT) and copper pyrithione (CPT), on microbial communities in estuarine sediments were studied in microcosms. As functional endpoints, fluxes of nutrients (NO3-, NH4+, HPO4(2-), Si(OH)4) and protein synthesis ([14C]leucine incorporation) were used, whereas molecular fingerprinting methods (polymerase chain reaction/denaturing gradient gel electrophoresis) were used to describe the bacterial community structure. The lowest-observed-effect concentration (LOEC) for ZPT was 0.001 nmol/g dry sediment for the phosphate flux and total DNA content, whereas the LOEC for CPT was 0.1 nmol/g dry sediment for the nitrate flux and total DNA content. Nitrate fluxes increased significantly following additions of both ZPT and CPT, whereas ammonium fluxes decreased significantly after ZPT addition, suggesting changes in the nitrification and denitrification processes. The total DNA content decreased significantly following addition of both ZPT and CPT, but at the highest addition of ZPT (10 nmol ZPT/g dry sediment), an increase in total DNA content was found. Increased protein synthesis and bacterial diversity were also observed at this concentration of ZPT, suggesting growth of tolerant opportunistic species.

  17. Exploring the potential interference of estuarine sediment contaminants with the DNA repair capacity of human hepatoma cells.

    PubMed

    Pinto, Miguel Ferreira; Louro, Henriqueta; Costa, Pedro M; Caeiro, Sandra; Silva, Maria João

    2015-01-01

    Estuaries may be reservoirs of a wide variety of pollutants, including mutagenic and carcinogenic substances that may impact on the ecosystem and human health. A previous study showed that exposure of human hepatoma (HepG2) cells to extracts from sediment samples collected in two areas (urban/industrial and riverine/agricultural) of an impacted estuary (Sado, Portugal), produced differential cytotoxic and genotoxic effects. Those effects were found to be consistent with levels and nature of sediment contamination. The present study aimed at evaluating whether the mixtures of contaminants contained in those extracts were able to modulate DNA repair capacity of HepG2 cells. The residual level of DNA damage was measured by the comet assay in cells exposed for 24 or 48 h to different extracts, after a short preexposure to a challenging concentration range of ethyl methanesulfonate (EMS), as a model alkylating agent. The results suggested that the mixture of contaminants present in the tested samples, besides a potential direct effect on the DNA molecule, may also interfere with DNA repair mechanisms in HepG2 cells, thus impairing their ability to deal with genotoxic stress and, possibly, facilitating accumulation of mutations. Humans are environmentally/occupationally exposed to mixtures rather than to single chemicals. Thus, the observation that estuarine contaminants induce direct and indirect DNA strand breakage in human cells, the latter through the impairment of DNA repair, raises additional concerns regarding potential hazards from exposure and the need to further explore these endpoints in the context of environmental risk assessment.

  18. Model-based interpretation of sediment concentration and vertical flux measurements in a shallow estuarine environment

    USGS Publications Warehouse

    Brand, Andreas; Lacy, Jessica R.; Gladding, Steve; Holleman, Rusty; Stacey, Mark

    2015-01-01

    A one-dimensional numerical model describing tidally varying vertical mixing and settling was used to interpret sediment concentrations and vertical fluxes observed in the shoals of South San Francisco Bay by two acoustic Doppler velocimeters (ADVs) at elevations of 0.36 m and 0.72 m above bed. Measured sediment concentrations changed by up to 100 g m−3 over the semidiurnal tidal cycle. These dynamics were dominated by local resuspension and settling. Multiple particle class models suggested the existence of a class with fast settling velocities (ws of 9.0 × 10−4 m s−1 in spring and 5.8 × 10−4 m s−1 in fall) and a slowly settling particle fraction (ws of <1 × 10−7 m s−1 in spring and 1.4 × 10−5 m s−1 in fall). Modeled concentrations of slowly settling particles at 0.36 m were as high as 20 g m−3 during fall and varied with the spring-neap cycle while fine sediment concentrations in spring were constant around 5 g m−3. Analysis of in situ water column floc size distributions suggested that floc properties in the lower part of the water column were most likely governed by particle-size distribution on the bed and not by coagulation, validating our multiple particle size approach. A comparison of different sediment bed models with respect to model performance, sensitivity, and identifiability suggested that the use of a sediment erosion model linear in bottom shear stress τb (E = M (τb − τc)) was the most appropriate choice to describe the field observations when the critical shear stress τc and the proportionality factor M were kept constant.

  19. Copper-complexing ligands produced by an intact estuarine microbial community in response to copper stress.

    NASA Astrophysics Data System (ADS)

    Bingham, J.; Dryden, C.; Gordon, A.

    2002-12-01

    Copper is both an important nutrient and a pollutant in the marine environment. By studying the interactions between microorganisms and copper in the Elizabeth River (VA), home to a major Naval Base, we field tested the hypothesis that picoplankton and/or bacterioplankton produce strong, copper-complexing ligands in response to elevated copper concentrations. A simple light/ dark test was used to distinguish between heterotrophic and phototrophic ligand production. Samples were bottled and moored, submerged one meter, for a week. Direct counts using DAPI stain and epiflourescence were conducted to find concentrations of picoplankton and bacterioplankton. Using cathodic stripping voltammetry, we found the total copper concentrations, and then from a titration of the ligands by copper, the ligand concentrations and conditional stability constants were obtained. The Elizabeth River naturally had between 10-20 nM total dissolved copper concentrations. However when copper complexation was considered we found that the levels of bio-available Cu(II) ions were much lower. In fact in the natural samples the levels were not high enough to affect the relative reproductive rates of several microorganisms. Naturally there was a 50 nM "buffer zone" of ligand to total dissolved copper concentration. Furthermore, when stressed with excess copper, healthy picoplankton produced enough ligand to alleviate toxicity, and rebuild the buffer zone. However bacterioplankton only produced enough ligand so that they were no longer affected. Therefore, intact estuarine communities regulate copper bioavailability and toxicity with ligand production.

  20. Rapid toxicity assessment of sediments from estuarine ecosystems: A new tandem in vitro testing approach

    USGS Publications Warehouse

    Johnson, B. Thomas; Long, E.R.

    1998-01-01

    Microtox?? and Mutatox?? were used to evaluate the acute toxicity and genotoxicity, respectively, of organic sediment extracts from Pensacola Bay and St. Andrew Bay, two estuaries that cover about 273 and 127 km2, respectively, along the Gulf coast of Florida, USA. The sensitivity and selectivity of these two bioluminescent toxicity assays were demonstrated in validation studies with over 50 pesticides, genotoxins, and industrial pollutants, both as single compounds and in complex mixtures. The 50% effective concentration (EC50) values of insecticides, petroleum products, and polychlorinated biphenyls determined by Microtox all tended to group around the mean EC50 value of 1.2 (0.8) mg/L. The polycyclic aromatic hydrocarbon sensitivity of Mutatox was in general similar to that reported in the Ames test. Surficial sediment samples were collected, extracted with dichloromethane, evaporated and concentrated under nitrogen, dissolved in dimethyl sulfoxide, assayed for acute toxicity and genotoxicity, and compared with reference sediments. Samples with low EC50 values, and determined to be genotoxic, were detected in Massalina Bayou, Watson Bayou, East Bay, and St. Andrew Bay-East in St. Andrew Bay as well as Bayou Grande, Bayou Chico, and Bayou Texar in Pensacola Bay. An overview of these data sets analyzed by Spearman rank correlation showed a significant correlation between acute toxicity and genotoxicity (p < 0.05). Microtox and Mutatox in tandem was a sensitive, cost-effective, and rapid (<24 h) screening tool that identified troublesome areas of pollution and assessed the potential sediment toxicity of lipophilic contaminants in aquatic ecosystems.

  1. Rapid toxicity assessment of sediments from estuarine ecosystems: A new tandem in vitro testing approach

    SciTech Connect

    Johnson, B.T.; Long, E.R.

    1998-06-01

    Microtox{reg_sign} and Mutatox{reg_sign} were used to evaluate the acute toxicity and genotoxicity, respectively, of organic sediment extracts from Pensacola Bay and St. Andrew Bay, two estuaries that cover about 273 and 127 km{sup 2}, respectively, along the Gulf coast of Florida, USA. The sensitivity and selectivity of these two bioluminescent toxicity assays were demonstrated in validation studies with over 50 pesticides, genotoxins, and industrial pollutants, both as single compounds and in complex mixtures. The 50% effective concentration (EC50) values of insecticides, petroleum products, and polychlorinated biphenyls determined by Microtox all tended to group around the mean EC50 value of 1.2 (0.8) mg/L. The polycyclic aromatic hydrocarbon sensitivity of Mutatox was in general similar to that reported in the Ames test. Surficial sediment samples were collected, extracted with dichloromethane, evaporated and concentrated under nitrogen, dissolved in dimethyl sulfoxide, assayed for acute toxicity and genotoxicity, and compared with reference sediments. Samples with low EC50 values, and determined to be genotoxic, were detected in Massalina Bayou, Watson Bayou, East Bay, and St. Andrew Bay-East in St. Andrew Bay as well as Bayou Grande, Bayou Chico, and Bayou Texas in Pensacola Bay. An overview of these data sets analyzed by Spearman rank correlation showed a significant correlation between acute toxicity and genotoxicity. Microtox and Mutatox in tandem was a sensitive, cost-effective, and rapid screening tool that identified troublesome areas of pollution and assessed the potential sediment toxicity of lipophilic contaminants in aquatic ecosystems.

  2. Transfer of chemical elements from a contaminated estuarine sediment to river water. A leaching assay

    NASA Astrophysics Data System (ADS)

    Abreu, Manuela; Peres, Sara; Magalhães, M. Clara F.

    2014-05-01

    Wastes of a former Portuguese steel industry were deposited during 40 years on the left bank of the Coina River, which flows into the estuary of the Tagus River near Lisbon. The aim of this study was to evaluate the release of the chemical elements from the contaminated sediment to the river water. A leaching experiment (four replicates) was performed using 1.6 kg/replicate of sediment from a landfill located in the Coina River bank, forming a lagoon subject to tidal influence. River water coming from this lagoon was collected during low tide. This water (200 mL) was added to the moist sediment, contained in cylindrical reactors, and was collected after 24 h of percolation. The leaching experiments were conducted for 77 days being leachates collected at time zero, after 28, 49 and 77 days with the sediment always moist. The sediment was characterized for: pH, electric conductivity (EC), total organic carbon (TOC), extractable phosphorus and potassium, mineral nitrogen, iron from iron oxides (crystalline and non-crystalline) and manganese oxides. Multi-elemental analysis was also made by ICP-INAA. Leachates and river water were analysed for pH, EC, hydrogencarbonate and sulfatetot by titrations, chloride by potentiometry, and multi-elemental composition by ICP-MS. The sediment presented pH=7.2, EC=18.5 dS/m, TOC=147.8 g/kg, high concentrations of extractable phosphorous (62.8 mg/kg) and potassium (1236.8 mg/kg), mineral nitrogen=11.3 mg/kg. The non-crystalline fraction of iron oxides corresponds to 99% (167.5 g Fe/kg) of the total iron oxides, and manganese from manganese oxides was low (52.7 mg/kg). Sediment is considered contaminated. It contained high concentrations (g/kg) of Zn (2.9), Pb (0.9), Cr (0.59), Cu (0.16), As (0.07), Cd (0.005), and Hg (0.001), which are above Canadian values for marine sediments quality guidelines for protection of aquatic life. River water had: pH=8.2, EC=28.6 dS/m, csulfate=1.23 g/L, and [Cl-]=251.6 mg/L. The concentrations of Cd (0

  3. A fugacity approach for assessing the bioaccumulation of hydrophobic organic compounds from estuarine sediment.

    PubMed

    Golding, Christopher J; Gobas, Frank A P C; Birch, Gavin F

    2008-05-01

    The bioavailability of four sediment-spiked hydrophobic organic contaminants (HOCs; chrysene, benzo[a]pyrene, chlordane, and Aroclor 1254) was investigated by comparing bioaccumulation by the amphipod Corophium colo with uptake into a thin film of ethylene/vinyl acetate (EVA) copolymer. The EVA thin film is a solid-phase extraction medium previously identified as effective at measuring the bioavailable contaminant fraction in sediment. The present study presents the results of 11 separate treatments in which chemical uptake into EVA closely matched uptake into lipid over 10 d. For all compounds, the concentration in EVA was a good approximation for the concentration in lipid, suggesting that this medium would be an appropriate biomimetic medium for assessing the bioaccumulation of HOCs during risk assessment of contaminated sediment. For chrysene and benzo[a]pyrene, limitations on bioaccumulation and toxicity because of low aqueous solubility were observed. The fugacity of the compounds in lipid (flip) and in the EVA thin film (fEVA) also was determined. The ratio of flip to fEVA was greater than one for all chemicals, indicating that all chemicals biomagnified over the duration of the exposure and demonstrating the potential for EVA thin-film extraction to assess trophic transfer of HOCs.

  4. Nitrogen reduction pathways in estuarine sediments: Influences of organic carbon and sulfide

    NASA Astrophysics Data System (ADS)

    Plummer, Patrick; Tobias, Craig; Cady, David

    2015-10-01

    Potential rates of sediment denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) were mapped across the entire Niantic River Estuary, CT, USA, at 100-200 m scale resolution consisting of 60 stations. On the estuary scale, denitrification accounted for ~ 90% of the nitrogen reduction, followed by DNRA and anammox. However, the relative importance of these reactions to each other was not evenly distributed through the estuary. A Nitrogen Retention Index (NIRI) was calculated from the rate data (DNRA/(denitrification + anammox)) as a metric to assess the relative amounts of reactive nitrogen being recycled versus retained in the sediments following reduction. The distribution of rates and accompanying sediment geochemical analytes suggested variable controls on specific reactions, and on the NIRI, depending on position in the estuary and that these controls were linked to organic carbon abundance, organic carbon source, and pore water sulfide concentration. The relationship between NIRI and organic carbon abundance was dependent on organic carbon source. Sulfide proved the single best predictor of NIRI, accounting for 44% of its observed variance throughout the whole estuary. We suggest that as a single metric, sulfide may have utility as a proxy for gauging the distribution of denitrification, anammox, and DNRA.

  5. Methanethiol accumulation exacerbates release of N2 O during denitrification in estuarine sediments and bacterial cultures.

    PubMed

    Magalhães, C; Kiene, R P; Buchan, A; Machado, A; Wiebe, W J; Bordalo, A A

    2011-06-01

    Microbes play critical roles in the biogeochemical cycling of nitrogen and sulfur in aquatic environments. Here we investigated the interaction between the naturally occurring organic sulfur compound methanethiol (MeSH) and the final step of the denitrification pathway, the reduction of nitrous oxide (N2 O) to dinitrogen (N2 ) gas, in sediment slurries from the temperate Douro and Ave estuaries (NW Portugal) and in pure cultures of the marine bacterium Ruegeria pomeroyi. Sediment slurries and cell suspensions were amended with a range of concentrations of either MeSH (0-120 µM) or methionine (0-5 mM), a known precursor of MeSH. MeSH or methionine additions caused N2 O to accumulate and this accumulation was linearly related to MeSH concentrations in both coastal sediments (R(2)  = 0.7-0.9, P < 0.05) and R. pomeroyi cell suspensions (R(2)  = 0.9, P < 0.01). Our results suggest that MeSH inhibits the final step of denitrification resulting in N2 O accumulation.

  6. Environmental availability of potentially toxic elements in estuarine sediments of the Cananéia-Iguape coastal system, Southeastern Brazil.

    PubMed

    Tramonte, Keila Modesto; Figueira, Rubens Cesar Lopes; de Lima Ferreira, Paulo Alves; Ribeiro, Andreza Portella; Batista, Miriam Fernanda; de Mahiques, Michel Michaelovitch

    2016-02-15

    The Cananéia-Iguape system is located in a Southeastern Brazilian coastal region, acknowledged by UNESCO as Biosphere Reserve of the Atlantic Rainforest. This system underwent important environmental changes due to the opening of the artificial channel of Valo Grande and by past intensive Pb ore mining activities. In view of this scenario, this study evaluated Cu, Pb and Zn availability in sediments from Cananéia-Iguape system, based on the content associated with the main components of the sediments. Moreover, in order to assess local contamination, the metals' contents were compared to Canadian quality guidelines, the past levels of metals preceding the mining activities and background sediment values. Concerning Cu and Zn in a state of chemical remobilization, both elements would possibly present no harm to the local communities. However, Pb available content exceeded the comparison values in various sampling sites, suggesting the need of monitoring regarding its bioavailability. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. 13C-DEPLETED MICROBIAL LIPIDS INDICATE SEASONAL METHANOTROPHIC ACTIVITY IN SHALLOW ESTUARINE SEDIMENTS

    EPA Science Inventory

    Compound specific isotope analysis was combined with phospholipid fatty acid (PLFA) analysis to identify methanotrophic activity in members of the sedimentary microbial community in the Altamaha and Savannah River estuaries in Georgia. 13C-depleted PLFAs indicate methane utilizat...

  8. Contaminants in water, sediment and fish biomonitor species from natural and artificial estuarine habitats along the urbanized Gold Coast, Queensland.

    PubMed

    Waltham, Nathan J; Teasdale, Peter R; Connolly, Rod M

    2011-12-01

    Metal and pesticide contaminants were measured in water, sediment and fish species in various Gold Coast waterways, Queensland. With the exception of Cu, metal concentrations in water, measured using the diffuse gradients in a thin film (DGT) technique, complied with relevant Australian guidelines. Cu concentrations in these waterways have been related to recreational vessel activities previously. All sediment metal concentrations measured were below the national guidelines, although Cu, Zn and Pb were found to vary significantly between habitat types. Evidence of spikes in sediment pesticide concentrations (some banned over 50 years ago) was observed in some artificial residential waterways. Heavy metals and pesticides were measured in the tissue (muscle, gills and liver) of three economically important species of fish, with different feeding strategies (partly herbivore Arrhamphus sclerolepis, carnivore Acanthopagrus australis, detritivore Mugil cephalus). We tested the hypothesis that fish accumulate different amounts of contaminants from wetland habitats affected by different intensities of anthropogenic activities (i.e., marinas, artificial residential canals, artificial residential lakes, estuaries and natural, vegetated waterways). Significantly higher concentrations of Cu were found in the gills of each fish species from marinas compared to fish caught in other waterways. Furthermore, fish caught in canals had the second highest Cu and natural waterways the lowest. These results support the stated hypothesis for Cu and furthermore indicate that these fish species are suitable as biomonitors in estuarine waterways. Metal and pesticide concentrations in the edible muscle tissue of all fish complied with the Australian Food Standard Code recommended limits for human consumption, apart from As which is likely to be due to bioconcentration of lower toxicity organo-As species. These results indicate a low health risk for humans consuming fish, in terms of

  9. Diversity and Abundance of Ammonia-Oxidizing Archaeal Nitrite Reductase (nirK) Genes in Estuarine Sediments of San Francisco Bay

    NASA Astrophysics Data System (ADS)

    Reji, L.; Lee, J. A.; Damashek, J.; Francis, C. A.

    2013-12-01

    Nitrification, the microbially-mediated aerobic oxidation of ammonia to nitrate via nitrite, is an integral component of the global biogeochemical nitrogen cycle. The first and rate-limiting step of nitrification, ammonia oxidation, is carried out by two distinct microbial groups: ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA). Molecular ecological studies targeting the amoA gene have revealed the abundance and ubiquity of AOA in terrestrial as well as aquatic environments. In addition to the ammonia oxidation machinery that includes the amoA gene, AOA also encode a gene for copper-containing nitrite reductase (nirK). The distribution patterns and functional role of nirK in AOA remain mostly unknown; proposed functions include the indirect involvement in ammonia oxidation through the production of nitric oxide during nitrite reduction, and (2) nitrite detoxification. In the present study, the diversity and abundance of archaeal nirK genes in estuarine sediments were investigated using quantitative polymerase chain reaction, cloning and sequencing approaches. In sediment samples collected from the San Francisco Bay estuary, two archaeal nirK variants (AnirKa and AnirKb) were amplified using specific primer sets. Overall, AnirKa was observed to be significantly more abundant than AnirKb in the sediment samples, with variation in relative abundance spanning two to three orders of magnitude between sampling sites. Phylogenetic analysis revealed a number of unique archaeal nirK sequence types, as well as many that clustered with sequences from previous estuarine studies and cultured AOA isolates, such as Nitrosopumilus maritimus. This study yielded new insights into the diversity and abundance of archaeal nirK genes in estuarine sediments, and highlights the importance of further investigating the physiological role of this gene in AOA, as well as its suitability as a marker gene for studying AOA in the environment.

  10. Estuarine water-quality and sediment data, and surface-water and ground-water-quality data, Naval Submarine Base Kings Bay, Camden County, Georgia, January 1999

    USGS Publications Warehouse

    Leeth, David C.; Holloway, Owen G.

    2000-01-01

    In January 1999, the U.S. Geological Survey collected estuarine-water, estuarine-sediment, surface-water, and ground-water quality samples in the vicinity of Naval Submarine Base Kings Bay, Camden County, Georgia. Data from these samples are used by the U.S. Navy to monitor the impact of submarine base activities on local water resources. Estuarine water and sediment data were collected from five sites on the Crooked River, Kings Bay, and Cumberland Sound. Surface-water data were collected from seven streams that discharge from Naval Submarine Base, Kings Bay. Ground-water data were collected from six ground-water monitoring wells completed in the water-table zone of the surficial aquifer at Naval Submarine Base Kings Bay. Samples were analyzed for nutrients, total and dissolved trace metals, total and dissolved organic carbon, oil and grease, total organic halogens, biological and chemical oxygen demand, and total and fecal coliform. Trace metals in ground and surface waters did not exceed U.S. Environmental Protection Agency Drinking Water Standards; and trace metals in surface water also did not exceed U.S. Environmental Protection Agency Surface Water Standards. These trace metals included arsenic, barium, cadmium, chromium, copper, lead, mercury, selenium, silver, tin, and zinc. Barium was detected in relatively high concentrations in ground water (concentrations ranged from 18 to 264 micrograms per liter). Two estuarine water samples exceeded the Georgia Department of Natural Resources, Environmental Protection Division standards for copper (concentrations of 6.2 and 3.0 micrograms per liter).

  11. Stable carbon isotopic apportionment of individual PAH in sediments from marine and estuarine environments

    SciTech Connect

    O`Malley, V.P.; Abrajano, T.A. Jr.; Hellou, J.

    1995-12-31

    Much interest has recently focused on the quantitative apportionment of multiple sources of organic contaminants in natural aquatic systems. Polycyclic aromatic hydrocarbons (PAH) are of great interest in this regard because in addition to their suspected toxic and carcinogenic properties, they also have a wide range of potential natural and anthropogenic sources. Here we present the results of a study where the primary source inputs of PAH to sediments of a Harbor and Estuary are quantitatively assessed using a combination of molecular abundance and carbon isotope measurements of individual (4- and 5-ring) PAH. Mass balance calculations using a simple two-component mixing model show that approximately 50 to 80% of the PAH input to the Harbour sediments is of combustion origin, and likely dominated by vehicular emissions. Direct petrogenic contribution, possibly crankcase oil, accounts for the remaining 20 to 50% of the total PAH input. PAH inputs to the Estuary seemed to be predominately of wood combustion origin but the presence of an unidentified isotopically depleted PAH source was also apparent.

  12. Genomic evidence for distinct carbon substrate preferences and ecological niches of Bathyarchaeota in estuarine sediments.

    PubMed

    Lazar, Cassandre Sara; Baker, Brett J; Seitz, Kiley; Hyde, Andrew S; Dick, Gregory J; Hinrichs, Kai-Uwe; Teske, Andreas P

    2016-04-01

    Investigations of the biogeochemical roles of benthic Archaea in marine sediments are hampered by the scarcity of cultured representatives. In order to determine their metabolic capacity, we reconstructed the genomic content of four widespread uncultured benthic Archaea recovered from estuary sediments at 48% to 95% completeness. Four genomic bins were found to belong to different subgroups of the former Miscellaneous Crenarcheota Group (MCG) now called Bathyarchaeota: MCG-6, MCG-1, MCG-7/17 and MCG-15. Metabolic predictions based on gene content of the different genome bins indicate that subgroup 6 has the ability to hydrolyse extracellular plant-derived carbohydrates, and that all four subgroups can degrade detrital proteins. Genes encoding enzymes involved in acetate production as well as in the reductive acetyl-CoA pathway were detected in all four genomes inferring that these Archaea are organo-heterotrophic and autotrophic acetogens. Genes involved in nitrite reduction were detected in all Bathyarchaeota subgroups and indicate a potential for dissimilatory nitrite reduction to ammonium. Comparing the genome content of the different Bathyarchaeota subgroups indicated preferences for distinct types of carbohydrate substrates and implicitly, for different niches within the sedimentary environment.

  13. Sediment Sampling in Estuarine Mudflats with an Aerial-Ground Robotic Team

    PubMed Central

    Deusdado, Pedro; Guedes, Magno; Silva, André; Marques, Francisco; Pinto, Eduardo; Rodrigues, Paulo; Lourenço, André; Mendonça, Ricardo; Santana, Pedro; Corisco, José; Almeida, Susana Marta; Portugal, Luís; Caldeira, Raquel; Barata, José; Flores, Luis

    2016-01-01

    This paper presents a robotic team suited for bottom sediment sampling and retrieval in mudflats, targeting environmental monitoring tasks. The robotic team encompasses a four-wheel-steering ground vehicle, equipped with a drilling tool designed to be able to retain wet soil, and a multi-rotor aerial vehicle for dynamic aerial imagery acquisition. On-demand aerial imagery, properly fused on an aerial mosaic, is used by remote human operators for specifying the robotic mission and supervising its execution. This is crucial for the success of an environmental monitoring study, as often it depends on human expertise to ensure the statistical significance and accuracy of the sampling procedures. Although the literature is rich on environmental monitoring sampling procedures, in mudflats, there is a gap as regards including robotic elements. This paper closes this gap by also proposing a preliminary experimental protocol tailored to exploit the capabilities offered by the robotic system. Field trials in the south bank of the river Tagus’ estuary show the ability of the robotic system to successfully extract and transport bottom sediment samples for offline analysis. The results also show the efficiency of the extraction and the benefits when compared to (conventional) human-based sampling. PMID:27618060

  14. Enrichment Factors (EF) on Superficial Sediments of Santos Estuarine System, Southeasthern Brazil

    NASA Astrophysics Data System (ADS)

    Kim, B. S. M.; Salaroli, A. B.; Mahiques, M.; Figueira, R.

    2014-12-01

    The Baixada Santista, located at southeastern Brazilian coast, hosts the largest harbor of South America, it is also the third most heavily populated region in São Paulo state. Many industries and domestic sewage have been contaminating the environment with heavy metals and arsenic since industrial revolution. This has been a major concern worldwide due to its toxicity and persistence. Levels of metals (Al, Cd, Cr, Cu, Ni, Pb, Zn, Fe, Mn, Sc, V) and As were determinated on 180 samples of surface sediments, by acid digestion and quantified by ICP-OES to assess enrichment factors in order to know the anthropogenic contribution of the investigated elements. The levels of metals indicated absence of contamination, but a higher enrichment of As (approximately 9.5) near Bertioga city. Ni and Cr had values between 0.5 - 2.0, Cu and Zn between 0.6 - 4.0 and 0.9 - 7.5 for Pb. Despite As, all others metals showed higher enrichment in Santos - São Vicente Estuary, especially near Cubatão. The analysis of the enrichment factor of As indicate that these values could be due to natural processes of weathering and sedimentation, meanwhile the other metals could be from antropogenic sources, since thoses values were found near industrial area.

  15. Novel chlorinated terphenyls in sediments and shellfish of an estuarine environment

    SciTech Connect

    Hale, R.C.; Greaves, J.; Gallagher, K.; Vadas, G.G. )

    1990-11-01

    Polychlorinated terphenyls (PCTs) are structurally similar to polychlorinated biphenyls (PCBs) and have been used in analogous applications. Aroclor 5432, a PCT formulation whose congeners contain predominantly two to five chlorines, was detected in sediments and oysters from a saltmarsh creek and an adjacent Chesapeake Bay tributary, Back River. Reports of the occurrence of Aroclor 5432 are virtually nonexistent, although sporadic reports of the more highly chlorinated PCT formulation Aroclor 5460 have been published. Capillary gas chromatography with electrolytic conductivity detection was used for quantitation. Identifications were confirmed by both electron ionization and negative chemical ionization mass spectrometry. Sediment concentrations detected were as high as 250,000 {mu}g/kg (dry-weight basis). Oysters collected from these areas contained up to 35,000 {mu}g/kg. This value is equivalent to 6,300 {mu}g/kg, on a wet-weight basis, and exceeds the applicable US limit for PCBs in edible shellfish by more than a factor of 3.

  16. A Random Forest approach to predict the spatial distribution of sediment pollution in an estuarine system.

    PubMed

    Walsh, Eric S; Kreakie, Betty J; Cantwell, Mark G; Nacci, Diane

    2017-01-01

    Modeling the magnitude and distribution of sediment-bound pollutants in estuaries is often limited by incomplete knowledge of the site and inadequate sample density. To address these modeling limitations, a decision-support tool framework was conceived that predicts sediment contamination from the sub-estuary to broader estuary extent. For this study, a Random Forest (RF) model was implemented to predict the distribution of a model contaminant, triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) (TCS), in Narragansett Bay, Rhode Island, USA. TCS is an unregulated contaminant used in many personal care products. The RF explanatory variables were associated with TCS transport and fate (proxies) and direct and indirect environmental entry. The continuous RF TCS concentration predictions were discretized into three levels of contamination (low, medium, and high) for three different quantile thresholds. The RF model explained 63% of the variance with a minimum number of variables. Total organic carbon (TOC) (transport and fate proxy) was a strong predictor of TCS contamination causing a mean squared error increase of 59% when compared to permutations of randomized values of TOC. Additionally, combined sewer overflow discharge (environmental entry) and sand (transport and fate proxy) were strong predictors. The discretization models identified a TCS area of greatest concern in the northern reach of Narragansett Bay (Providence River sub-estuary), which was validated with independent test samples. This decision-support tool performed well at the sub-estuary extent and provided the means to identify areas of concern and prioritize bay-wide sampling.

  17. PCB congener distribution in estuarine water, sediment and fish samples: implications for monitoring programs.

    PubMed

    Fikslin, Thomas J; Santoro, Edward D

    2003-09-01

    Traditional analyses for PCBs in environmental matrices have focused on commercial Aroclor mixtures with detection limits in the 100 to 1000 part per trillion range. This approach has recently been supplanted by analyses for specific PCB compounds called congeners with detection limits less than 0.5 ppt. At the national level, total PCB determinations based upon selected PCB congeners typically characterize analyses of surface water, sediment and tissue. These federal efforts rely on a suite of 18 to 20 congeners out of a total of 209 congeners to characterize total PCB. The present study compares total PCB estimates based upon this subset of congeners with estimates based upon an expanded list of 81 congeners from water, sediment and fish tissue collected from the Delaware Estuary. Analytical data from monitoring programs conducted in the Delaware Estuary by the Delaware River Basin Commission, NOAA National Ocean Service, U.S. Army Corps of Engineers and the U.S. Environmental Protection Agency from 1996 to 1998 were evaluated. Total PCB estimates derived from the different sets of congeners, including the adjustment factor of 2.0 used by NOAA, were compared. This evaluation indicated that differences exist between total PCB determinations based upon these approaches, and that these differences vary depending on the matrix analyzed. The bias associated with using a smaller set of PCB congeners, and the implications for risk assessment are discussed.

  18. Sediment Sampling in Estuarine Mudflats with an Aerial-Ground Robotic Team.

    PubMed

    Deusdado, Pedro; Guedes, Magno; Silva, André; Marques, Francisco; Pinto, Eduardo; Rodrigues, Paulo; Lourenço, André; Mendonça, Ricardo; Santana, Pedro; Corisco, José; Almeida, Susana Marta; Portugal, Luís; Caldeira, Raquel; Barata, José; Flores, Luis

    2016-09-09

    This paper presents a robotic team suited for bottom sediment sampling and retrieval in mudflats, targeting environmental monitoring tasks. The robotic team encompasses a four-wheel-steering ground vehicle, equipped with a drilling tool designed to be able to retain wet soil, and a multi-rotor aerial vehicle for dynamic aerial imagery acquisition. On-demand aerial imagery, properly fused on an aerial mosaic, is used by remote human operators for specifying the robotic mission and supervising its execution. This is crucial for the success of an environmental monitoring study, as often it depends on human expertise to ensure the statistical significance and accuracy of the sampling procedures. Although the literature is rich on environmental monitoring sampling procedures, in mudflats, there is a gap as regards including robotic elements. This paper closes this gap by also proposing a preliminary experimental protocol tailored to exploit the capabilities offered by the robotic system. Field trials in the south bank of the river Tagus' estuary show the ability of the robotic system to successfully extract and transport bottom sediment samples for offline analysis. The results also show the efficiency of the extraction and the benefits when compared to (conventional) human-based sampling.

  19. Mangrove succession enriches the sediment microbial community in South China

    PubMed Central

    Chen, Quan; Zhao, Qian; Li, Jing; Jian, Shuguang; Ren, Hai

    2016-01-01

    Sediment microorganisms help create and maintain mangrove ecosystems. Although the changes in vegetation during mangrove forest succession have been well studied, the changes in the sediment microbial community during mangrove succession are poorly understood. To investigate the changes in the sediment microbial community during succession of mangroves at Zhanjiang, South China, we used phospholipid fatty acid (PLFA) analysis and the following chronosequence from primary to climax community: unvegetated shoal; Avicennia marina community; Aegiceras corniculatum community; and Bruguiera gymnorrhiza + Rhizophora stylosa community. The PLFA concentrations of all sediment microbial groups (total microorganisms, fungi, gram-positive bacteria, gram-negative bacteria, and actinomycetes) increased significantly with each stage of mangrove succession. Microbial PLFA concentrations in the sediment were significantly lower in the wet season than in the dry season. Regression and ordination analyses indicated that the changes in the microbial community with mangrove succession were mainly associated with properties of the aboveground vegetation (mainly plant height) and the sediment (mainly sediment organic matter and total nitrogen). The changes in the sediment microbial community can probably be explained by increases in nutrients and microhabitat heterogeneity during mangrove succession. PMID:27265262

  20. Mangrove succession enriches the sediment microbial community in South China.

    PubMed

    Chen, Quan; Zhao, Qian; Li, Jing; Jian, Shuguang; Ren, Hai

    2016-06-06

    Sediment microorganisms help create and maintain mangrove ecosystems. Although the changes in vegetation during mangrove forest succession have been well studied, the changes in the sediment microbial community during mangrove succession are poorly understood. To investigate the changes in the sediment microbial community during succession of mangroves at Zhanjiang, South China, we used phospholipid fatty acid (PLFA) analysis and the following chronosequence from primary to climax community: unvegetated shoal; Avicennia marina community; Aegiceras corniculatum community; and Bruguiera gymnorrhiza + Rhizophora stylosa community. The PLFA concentrations of all sediment microbial groups (total microorganisms, fungi, gram-positive bacteria, gram-negative bacteria, and actinomycetes) increased significantly with each stage of mangrove succession. Microbial PLFA concentrations in the sediment were significantly lower in the wet season than in the dry season. Regression and ordination analyses indicated that the changes in the microbial community with mangrove succession were mainly associated with properties of the aboveground vegetation (mainly plant height) and the sediment (mainly sediment organic matter and total nitrogen). The changes in the sediment microbial community can probably be explained by increases in nutrients and microhabitat heterogeneity during mangrove succession.

  1. Mangrove succession enriches the sediment microbial community in South China

    NASA Astrophysics Data System (ADS)

    Chen, Quan; Zhao, Qian; Li, Jing; Jian, Shuguang; Ren, Hai

    2016-06-01

    Sediment microorganisms help create and maintain mangrove ecosystems. Although the changes in vegetation during mangrove forest succession have been well studied, the changes in the sediment microbial community during mangrove succession are poorly understood. To investigate the changes in the sediment microbial community during succession of mangroves at Zhanjiang, South China, we used phospholipid fatty acid (PLFA) analysis and the following chronosequence from primary to climax community: unvegetated shoal; Avicennia marina community; Aegiceras corniculatum community; and Bruguiera gymnorrhiza + Rhizophora stylosa community. The PLFA concentrations of all sediment microbial groups (total microorganisms, fungi, gram-positive bacteria, gram-negative bacteria, and actinomycetes) increased significantly with each stage of mangrove succession. Microbial PLFA concentrations in the sediment were significantly lower in the wet season than in the dry season. Regression and ordination analyses indicated that the changes in the microbial community with mangrove succession were mainly associated with properties of the aboveground vegetation (mainly plant height) and the sediment (mainly sediment organic matter and total nitrogen). The changes in the sediment microbial community can probably be explained by increases in nutrients and microhabitat heterogeneity during mangrove succession.

  2. A Random Forest approach to predict the spatial distribution of sediment pollution in an estuarine system

    PubMed Central

    Kreakie, Betty J.; Cantwell, Mark G.; Nacci, Diane

    2017-01-01

    Modeling the magnitude and distribution of sediment-bound pollutants in estuaries is often limited by incomplete knowledge of the site and inadequate sample density. To address these modeling limitations, a decision-support tool framework was conceived that predicts sediment contamination from the sub-estuary to broader estuary extent. For this study, a Random Forest (RF) model was implemented to predict the distribution of a model contaminant, triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) (TCS), in Narragansett Bay, Rhode Island, USA. TCS is an unregulated contaminant used in many personal care products. The RF explanatory variables were associated with TCS transport and fate (proxies) and direct and indirect environmental entry. The continuous RF TCS concentration predictions were discretized into three levels of contamination (low, medium, and high) for three different quantile thresholds. The RF model explained 63% of the variance with a minimum number of variables. Total organic carbon (TOC) (transport and fate proxy) was a strong predictor of TCS contamination causing a mean squared error increase of 59% when compared to permutations of randomized values of TOC. Additionally, combined sewer overflow discharge (environmental entry) and sand (transport and fate proxy) were strong predictors. The discretization models identified a TCS area of greatest concern in the northern reach of Narragansett Bay (Providence River sub-estuary), which was validated with independent test samples. This decision-support tool performed well at the sub-estuary extent and provided the means to identify areas of concern and prioritize bay-wide sampling. PMID:28738089

  3. Integrated assessment of estuarine sediment quality based on a multi-biomarker approach in the bivalve Scrobicularia plana.

    PubMed

    Tankoua, O Fossi; Buffet, Pe; Amiard, J C; Berthet, B; Mouneyrac, C; Amiard-Triquet, C

    2013-02-01

    The bivalve Scrobicularia plana has been proposed as a sentinel species for the assessment of estuarine sediment quality. The aim of this study was to test the responsiveness of a set of biomarkers in bivalves originating from a moderately contaminated site (Loire estuary, France) and a comparatively cleaner site (Bay of Bourgneuf, France) used as reference. Temporal fluctuations were examined in animals collected on eight occasions from March 2008 to October 2009 for the determination of biochemical (MTs, GST, AChE), physiological (energy reserves as glycogen and lipids, condition, hepato-somatic and gonado-somatic indices), and behavioural biomarkers (burrowing). Metals in clams were examined with the aim of understanding the variations in MT concentrations. The current findings indicate that among biochemical markers MTs must be used in a precautionary fashion, and comparison with a reference site remains indispensable together with an appreciation of any salinity effects. Clearer responses were obtained for GST activity which contributes to defence against organic compounds. However, any such defence was not sufficient to ensure total protection since a number of impairments were observed at the individual level (burrowing behaviour, condition index, gonado-somatic index). The integrated biomarker response (IBR) illustrated higher levels of stress in clams collected from the Loire estuary compared to those gathered from the reference site at most of the sampling periods. The interpretation of responses involved in the cascade of energetic events (from available food, digestive enzyme activities, energy reserves to condition and reproductive status) is complex but did reveal disturbances in the Loire estuary which is far from being the most contaminated estuary in France and over the world. However, no links can be established between effects at individual and supra-individual levels in organisms in the Loire estuary, even in the case of a small oil spill which

  4. MODIS-based retrieval of suspended sediment concentration and diffuse attenuation coefficient in Chinese estuarine and coastal waters

    NASA Astrophysics Data System (ADS)

    Sokoletsky, Leonid; Yang, Xianping; Shen, Fang

    2014-11-01

    Radiative transfer modelling in atmosphere, water, and on the air-water surface was used to create an algorithm and computer code for satellite monitoring Chinese estuarine and coastal waters. The atmospheric part of the algorithm is based on the Reference Evaluation of Solar Transmittance (REST) model for calculation of optical properties of the atmosphere from the top of the atmosphere to the target; for modelling optical properties from target towards satellite's sensor, an optical reciprocity principle has been used. An algorithm uses estimates derived from three different sources: 1) the MODIS-based software; 2) radiative transfer equations, and 3) well-known empirical relationships between measured parameters and optical depths and transmittances for such atmospheric components as molecules, aerosols, ozone, nitrogen dioxide, precipitable water vapor and uniformly mixed gases. Using this model allowed us to derive a reliable relationship relating an important parameter, the diffuse-to-global solar incoming irradiance ratio, to the aerosol optical thickness, solar zenith angle and wavelength. The surface and underwater parts of the algorithm contained theoretical and semi-empirical relationships between inherent (such as absorption, scattering and backscattering coefficients) and apparent (remote-sensing reflectance and diffuse attenuation coefficient, Kd) optical properties, and suspended sediment concentration (SSC) measured in the Yangtze River Estuary and its adjacent coastal area. The first false colour maps of SSC and Kd demonstrated a well accordance with the multi-year field observations in the region, and suggest promise for use of this algorithm for the regular monitoring of Chinese and worldwide natural waters.

  5. Community Dynamics and Activity of Ammonia-Oxidizing Prokaryotes in Intertidal Sediments of the Yangtze Estuary

    PubMed Central

    Zheng, Yanling; Newell, Silvia; Liu, Min; Zhou, Junliang; Zhao, Hui; You, Lili; Cheng, Xunliang

    2014-01-01

    Diversity, abundance, and activity of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) were investigated using the ammonia monooxygenase α subunit (amoA) in the intertidal sediments of the Yangtze Estuary. Generally, AOB had a lower diversity of amoA genes than did AOA in this study. Clone library analysis revealed great spatial variations in both AOB and AOA communities along the estuary. The UniFrac distance matrix showed that all the AOB communities and 6 out of 7 AOA communities in the Yangtze Estuary were statistically indistinguishable between summer and winter. The studied AOB and AOA community structures were observed to correlate with environmental parameters, of which salinity, pH, ammonium, total phosphorus, and organic carbon had significant correlations with the composition and distribution of both communities. Also, the AOA communities were significantly correlated with sediment clay content. Quantitative PCR (qPCR) results indicated that the abundance of AOB amoA genes was greater than that of AOA amoA genes in 10 of the 14 samples analyzed in this study. Potential nitrification rates were significantly greater in summer than in winter and had a significant negative correlation with salinity. In addition, potential nitrification rates were correlated strongly only with archaeal amoA gene abundance and not with bacterial amoA gene abundance. However, no significant differences were observed between rates measured with and without ampicillin (AOB inhibitor). These results implied that archaea might play a more important role in mediating the oxidation of ammonia to nitrite in the Yangtze estuarine sediments. PMID:24185847

  6. Community dynamics and activity of ammonia-oxidizing prokaryotes in intertidal sediments of the Yangtze estuary.

    PubMed

    Zheng, Yanling; Hou, Lijun; Newell, Silvia; Liu, Min; Zhou, Junliang; Zhao, Hui; You, Lili; Cheng, Xunliang

    2014-01-01

    Diversity, abundance, and activity of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) were investigated using the ammonia monooxygenase α subunit (amoA) in the intertidal sediments of the Yangtze Estuary. Generally, AOB had a lower diversity of amoA genes than did AOA in this study. Clone library analysis revealed great spatial variations in both AOB and AOA communities along the estuary. The UniFrac distance matrix showed that all the AOB communities and 6 out of 7 AOA communities in the Yangtze Estuary were statistically indistinguishable between summer and winter. The studied AOB and AOA community structures were observed to correlate with environmental parameters, of which salinity, pH, ammonium, total phosphorus, and organic carbon had significant correlations with the composition and distribution of both communities. Also, the AOA communities were significantly correlated with sediment clay content. Quantitative PCR (qPCR) results indicated that the abundance of AOB amoA genes was greater than that of AOA amoA genes in 10 of the 14 samples analyzed in this study. Potential nitrification rates were significantly greater in summer than in winter and had a significant negative correlation with salinity. In addition, potential nitrification rates were correlated strongly only with archaeal amoA gene abundance and not with bacterial amoA gene abundance. However, no significant differences were observed between rates measured with and without ampicillin (AOB inhibitor). These results implied that archaea might play a more important role in mediating the oxidation of ammonia to nitrite in the Yangtze estuarine sediments.

  7. Microbial Communities in Sediments of Lagos Lagoon, Nigeria: Elucidation of Community Structure and Potential Impacts of Contamination by Municipal and Industrial Wastes

    PubMed Central

    Obi, Chioma C.; Adebusoye, Sunday A.; Ugoji, Esther O.; Ilori, Mathew O.; Amund, Olukayode O.; Hickey, William J.

    2016-01-01

    Estuarine sediments are significant repositories of anthropogenic contaminants, and thus knowledge of the impacts of pollution upon microbial communities in these environments is important to understand potential effects on estuaries as a whole. The Lagos lagoon (Nigeria) is one of Africa’s largest estuarine ecosystems, and is impacted by hydrocarbon pollutants and other industrial and municipal wastes. The goal of this study was to elucidate microbial community structure in Lagos lagoon sediments to identify groups that may be adversely affected by pollution, and those that may serve as degraders of environmental contaminants, especially polycyclic aromatic hydrocarbons (PAHs). Sediment samples were collected from sites that ranged in types and levels of anthropogenic impacts. The sediments were characterized for a range of physicochemical properties, and microbial community structure was determined by Illumina sequencing of the 16S rRNA genes. Microbial diversity (species richness and evenness) in the Apapa and Eledu sediments was reduced compared to that of the Ofin site, and communities of both of the former two were dominated by a single operational taxonomic unit (OTU) assigned to the family Helicobacteraceae (Epsilonproteobacteria). In the Ofin community, Epsilonproteobacteria were minor constituents, while the major groups were Cyanobacteria, Bacteroidetes, and Firmicutes, which were all minor in the Apapa and Eledu sediments. Sediment oxygen demand (SOD), a broad indicator of contamination, was identified by multivariate analyses as strongly correlated with variation in alpha diversity. Environmental variables that explained beta diversity patterns included SOD, as well as levels of naphthalene, acenaphthylene, cobalt, cadmium, total organic matter, or nitrate. Of 582 OTU identified, abundance of 167 was significantly correlated (false discovery rate q≤ 0.05) to environmental variables. The largest group of OTU correlated with PAH levels were PAH

  8. Microbial Communities in Sediments of Lagos Lagoon, Nigeria: Elucidation of Community Structure and Potential Impacts of Contamination by Municipal and Industrial Wastes.

    PubMed

    Obi, Chioma C; Adebusoye, Sunday A; Ugoji, Esther O; Ilori, Mathew O; Amund, Olukayode O; Hickey, William J

    2016-01-01

    Estuarine sediments are significant repositories of anthropogenic contaminants, and thus knowledge of the impacts of pollution upon microbial communities in these environments is important to understand potential effects on estuaries as a whole. The Lagos lagoon (Nigeria) is one of Africa's largest estuarine ecosystems, and is impacted by hydrocarbon pollutants and other industrial and municipal wastes. The goal of this study was to elucidate microbial community structure in Lagos lagoon sediments to identify groups that may be adversely affected by pollution, and those that may serve as degraders of environmental contaminants, especially polycyclic aromatic hydrocarbons (PAHs). Sediment samples were collected from sites that ranged in types and levels of anthropogenic impacts. The sediments were characterized for a range of physicochemical properties, and microbial community structure was determined by Illumina sequencing of the 16S rRNA genes. Microbial diversity (species richness and evenness) in the Apapa and Eledu sediments was reduced compared to that of the Ofin site, and communities of both of the former two were dominated by a single operational taxonomic unit (OTU) assigned to the family Helicobacteraceae (Epsilonproteobacteria). In the Ofin community, Epsilonproteobacteria were minor constituents, while the major groups were Cyanobacteria, Bacteroidetes, and Firmicutes, which were all minor in the Apapa and Eledu sediments. Sediment oxygen demand (SOD), a broad indicator of contamination, was identified by multivariate analyses as strongly correlated with variation in alpha diversity. Environmental variables that explained beta diversity patterns included SOD, as well as levels of naphthalene, acenaphthylene, cobalt, cadmium, total organic matter, or nitrate. Of 582 OTU identified, abundance of 167 was significantly correlated (false discovery rate q≤ 0.05) to environmental variables. The largest group of OTU correlated with PAH levels were PAH

  9. The Impact of Salinity on the Diversity of Microbial Sediment Communities

    NASA Astrophysics Data System (ADS)

    McLean, C.; Cardarelli, E.; Lee, J. A.; Francis, C. A.

    2014-12-01

    The nitrogen cycle is a global process, largely mediated by microorganisms, that exchanges nitrogen between its biologically available forms (NH4+, NO3-) and its inert (N2) form. This cycle enables the biological uptake of nitrogen for the formation of DNA, amino acids, and other biological compounds critical to life. Several processes are responsible for facilitating the cycling of nitrogen through eight different oxidation states. Two nitrogen removal processes include anaerobic ammonium oxidation (anammox), in which N2 is produced directly from ammonia and nitrite, and denitrification, the sequential oxidation of NO3 to N2. Together, these two processes play a large role in determining the biological availability of nitrogen in estuarine ecosystems. To better understand how microbial communities conducting these processes change under varying environmental conditions, a manipulation experiment was developed to simulate an environmental site salinity shift. Sediment cores were collected from north San Francisco Bay in the Carquinez Strait, a site of seasonally varying salinity. These cores from the Carquinez Strait were incubated in two treatments: one with local brackish water and one with freshwater from Suisun Bay. Using Sanger sequencing, we examined shifts in the microbial communities containing the functional genes hzsA (anammox) and nirS (denitrification). Geochemical characteristics such as NO3- and NH4+ concentrations in the water and the C:N ratio of the sediment were measured to determine subsequent changes these communities had on the sediment chemistry. This study provides insight into how changes in salinity affect microbial sediment community composition in San Francisco Bay.

  10. Bacterial reworking of terrigenous and marine organic matter in estuarine water columns and sediments

    NASA Astrophysics Data System (ADS)

    Bourgoin, Luc-Henri; Tremblay, Luc

    2010-10-01

    Amino acids and the bacterial biomarkers muramic acid and D-amino acids were quantified in the ultrafiltered dissolved, particulate and sedimentary organic matter (UDOM, POM and SOM) of the St. Lawrence system (Canada). The main objectives were to better describe the fate of terrigenous and marine organic matter (OM) in coastal zones and to quantify the bacterial contributions to OM composition and diagenesis. Regardless of their origin, the carbon (C) content of the particles substantially decreased with depth, especially near the water-sediment interface. Major diagenetic transformations of organic nitrogen (N) were revealed and important differences were observed between terrigenous and marine OM. Amino acid contents of particles decreased by 66-93% with depth and accounted for 12-30% of the particulate C losses in marine locations. These percentages were respectively 18-56% and 7-11% in the Saguenay Fjord where terrigenous input is important. A preferential removal of particulate N and amino acids with depth or during transport was measured, but only in marine locations and for N-rich particles. This leads to very low amino acid yields in deep marine POM. However, these yields then increased to a level up to three times higher after deposition on sediments, where SOM showed lower C:N ratios than deep POM. The associated increase of bacterial biomarker yields suggests an active in situ resynthesis of amino acids by benthic bacteria. The N content of the substrate most likely determines whether a preferential degradation or an enrichment of N and amino acid are observed. For N-poor OM, such as terrigenous or deep marine POM, the incorporation of exogenous N by attached bacteria can be measured, while the organic N is preferentially used or degraded in N-rich OM. Compared to the POM from the same water samples, the extracted UDOM was poor in N and amino acids and appeared to be mostly made of altered plant and bacterial fragments. Signs of in situ marine

  11. Distribution and mass inventory of mercury in sediment from the Yangtze River estuarine-inner shelf of the East China Sea

    NASA Astrophysics Data System (ADS)

    Liu, Wenchuan; Hu, Limin; Lin, Tian; Li, Yuanyuan; Guo, Zhigang

    2017-01-01

    Mercury (Hg) was measured in 70 sediment samples from the Yangtze River estuarine-inner shelf of the East China Sea (ECS) to evaluate its occurrence, distribution, and deposition flux. Its concentrations were 10-92 ng/g with a mean of 46±17 ng/g. A decrease of Hg concentration with increasing distance offshore suggested a dominance of riverine input. The high levels of Hg observed at the southern inner shelf were partly due to the sorption affinity of fine-grained sediments. Hg concentration was significantly correlated with total organic carbon content and sediment grain size, implying that the nature of sedimentary organic matter and hydrodynamic forces could influence the Hg occurrence. A moderate correlation between Hg with high-molecular-weight polycyclic aromatic hydrocarbons in the YRE suggested that they shared a similar input pathway. The total deposition flux of Hg was estimated to be 52 t/y with a deposition rate of 6-120 ng/cm2 y, which indicated that the estuarine-inner shelf of the ECS was a major sink of Hg in the margins off China, and this area could play a significant role in the Hg biogeochemical cycle on a global scale.

  12. Spatial and temporal variability of contaminants within estuarine sediments and native Olympia oysters: A contrast between a developed and an undeveloped estuary.

    PubMed

    Granek, Elise F; Conn, Kathleen E; Nilsen, Elena B; Pillsbury, Lori; Strecker, Angela L; Rumrill, Steve S; Fish, William

    2016-07-01

    Chemical contaminants can be introduced into estuarine and marine ecosystems from a variety of sources including wastewater, agriculture and forestry practices, point and non-point discharges, runoff from industrial, municipal, and urban lands, accidental spills, and atmospheric deposition. The diversity of potential sources contributes to the likelihood of contaminated marine waters and sediments and increases the probability of uptake by marine organisms. Despite widespread recognition of direct and indirect pathways for contaminant deposition and organismal exposure in coastal systems, spatial and temporal variability in contaminant composition, deposition, and uptake patterns are still poorly known. We investigated these patterns for a suite of persistent legacy contaminants including polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) and chemicals of emerging concern including pharmaceuticals within two Oregon coastal estuaries (Coos and Netarts Bays). In the more urbanized Coos Bay, native Olympia oyster (Ostrea lurida) tissue had approximately twice the number of PCB congeners at over seven times the total concentration, yet fewer PBDEs at one-tenth the concentration as compared to the more rural Netarts Bay. Different pharmaceutical suites were detected during each sampling season. Variability in contaminant types and concentrations across seasons and between species and media (organisms versus sediment) indicates the limitation of using indicator species and/or sampling annually to determine contaminant loads at a site or for specific species. The results indicate the prevalence of legacy contaminants and CECs in relatively undeveloped coastal environments highlighting the need to improve policy and management actions to reduce contaminant releases into estuarine and marine waters and to deal with legacy compounds that remain long after prohibition of use. Our results point to the need for better understanding of the ecological and

  13. Spatial and temporal variability of contaminants within estuarine sediments and native Olympia oysters: A contrast between a developed and an undeveloped estuary

    USGS Publications Warehouse

    Granek, Elise F.; Conn, Kathleen E.; Nilsen, Elena B.; Pillsbury, Lori; Strecker, Angela; Rumrill, Steve; Fish, William

    2016-01-01

    Chemical contaminants can be introduced into estuarine and marine ecosystems from a variety of sources including wastewater, agriculture and forestry practices, point and non-point discharges, runoff from industrial, municipal, and urban lands, accidental spills, and atmospheric deposition. The diversity of potential sources contributes to the likelihood of contaminated marine waters and sediments and increases the probability of uptake by marine organisms. Despite widespread recognition of direct and indirect pathways for contaminant deposition and organismal exposure in coastal systems, spatial and temporal variability in contaminant composition, deposition, and uptake patterns are still poorly known. We investigated these patterns for a suite of persistent legacy contaminants including polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) and chemicals of emerging concern including pharmaceuticals within two Oregon coastal estuaries (Coos and Netarts Bays). In the more urbanized Coos Bay, native Olympia oyster (Ostrea lurida) tissue had approximately twice the number of PCB congeners at over seven times the total concentration, yet fewer PBDEs at one-tenth the concentration as compared to the more rural Netarts Bay. Different pharmaceutical suites were detected during each sampling season. Variability in contaminant types and concentrations across seasons and between species and media (organisms versus sediment) indicates the limitation of using indicator species and/or sampling annually to determine contaminant loads at a site or for specific species. The results indicate the prevalence of legacy contaminants and CECs in relatively undeveloped coastal environments highlighting the need to improve policy and management actions to reduce contaminant releases into estuarine and marine waters and to deal with legacy compounds that remain long after prohibition of use. Our results point to the need for better understanding of the ecological and

  14. Effects of adaptation on biodegradation rates in sediment/water cores from estuarine and freshwater environments

    SciTech Connect

    Spain, J.C.; Pritchard, P.H.; Bourquin, A.W.

    1980-10-01

    Experiments were devised to determine whether exposure to xenobiotics would cause microbial populations to degrade the compounds more rapidly during subsequent exposures. Studies were done with water/sediment systems (ecocores) taken from a salt marsh and a river. Systems were tested for adaptation to the model compounds methyl parathion and p-nitrophenol. /sup 14/CO/sub 2/ released from radioactive parent compounds was used as a measure of mineralization. River populations preexposed to p-nitrophenol at concentrations as low as 60 ..mu..g/liter degraded the nitrophenol much faster than did control populations. River populations preexposed to methyl parathion also adapted to degrade the pesticide more rapidly, but higher concentrations were required. Salt marsh populations did not adapt to degrade methyl parathion. p-nitrophenol-degrading bacteria were isolated from river samples but not from salt marsh samples. Numbers of nitrophenol-degrading bacteria increased 4 to 5 orders of magnitude during adaptation. Results indicate that the ability of populations to adapt depends on the presence of specific microorganisms. Biodegradation rates in laboratory systems can be affected by concentration and prior exposure; therefore, adaptation must be considered when such systems are used to predict the fate of xenobiotics in the environment.

  15. Streptomyces chitinivorans sp. nov., a chitinolytic strain isolated from estuarine lake sediment.

    PubMed

    Ray, Lopamudra; Mishra, Samir Ranjan; Panda, Ananta Narayan; Das, Surajit; Rastogi, Gurdeep; Pattanaik, Ajit Kumar; Adhya, Tapan Kumar; Suar, Mrutyunjay; Raina, Vishakha

    2016-09-01

    A novel actinobacterial strain RC1832T was isolated from the sediment of a fish dumping yard at Balugaon near Chilika Lake. The strain is halotolerant (15 % NaCl, w/v), alkali-tolerant (pH 7-10) and hydrolyzes chitin, starch, gelatin, cellulose, carboxymethyl cellulose, Tween 80, tributyrin, lecithin and casein. Apart from showing typical genus-specific morphological and chemotaxonomic features, the comparision and analysis of the near complete 16S rRNA gene sequence clearly revealed that the strain RC1832T represented a member of the genus Streptomyces. It exhibited the highest sequence similarities with the strains Streptomyces fenghuangensis GIMN4.003T (99.78 %), Streptomyces nanhaiensis DSM 41926T (99.07 %), Streptomyces radiopugnans R97T(98.71 %), Streptomyces atacamensis DSM 42065T (98.65 %) and Streptomyces barkulensis DSM 42082T (98.25 %). The DNA-DNA relatedness of strain RC 1832T with the closest phylogenetic neighbours S. fenghuangensis GIMN4.003T and S. nanhaiensis DSM 41926T were 20±2 % and 21±2 %, respectively. Thus, based on a range of phenotypic and genotypic properties, strain RC1832T was suggested to represent a novel species of the genus Streptomyces for which the name Streptomyces chitinivorans sp. nov. is proposed. The type strain is RC1832T (=JCM 30611=KCTC 29696).

  16. Sediment Bacterial Communities Reflect the History of a Sea Basin

    PubMed Central

    Lyra, Christina; Sinkko, Hanna; Rantanen, Matias; Paulin, Lars; Kotilainen, Aarno

    2013-01-01

    How entire microbial communities are structured across stratified sediments from the historical standpoint is unknown. The Baltic Sea is an ideal research object for historical reconstruction, since it has experienced many fresh- and brackish water periods and is depleted of dissolved oxygen, which increases the sediment's preservation potential. We investigated the bacterial communities, chemical elements (e.g. Cr, Pb Na, P, Sr and U) and sediment composition in a stratified sediment core dated by radiocarbon and spanning 8000 years of Baltic Sea history, using up-to-date multivariate statistics. The communities were analysed by 16S rRNA gene terminal restriction fragment length polymorphism. The communities of the deep Early Litorina and surface Late Litorina Sea laminae were separated from the communities of the middle Litorina Sea laminae, which were associated with elevated concentrations of U and Sr trace elements, palaeo-oxygen and palaeosalinity proxies. Thus, the Litorina Sea laminae were characterized by past oxygen deficiency and salinity increase. The communities of the laminae, bioturbated and homogeneous sediments were differentiated, based on the same historical sea phases, with correct classifications of 90%. Palaeosalinity was one of the major parameters that separated the bacterial communities of the stratified sediments. A discontinuous spatial structure with a surprising increase in community heterogeneity was detected in Litorina Sea sediments from 388 to 422 cm deep, which suggests that a salinity maximum occurred in the central Gulf of Finland app. 6200–6600 years ago. The community heterogeneity decreased from the surface down to 306 cm, which reflected downcore mineralization. The plateau of the decrease was in the app. 2000-year-old sediment layers. Bacterial community data may be used as an additional tool in ocean-drilling projects, in which it is important to detect mineralization plateaus both to determine historically comparable

  17. Assessing contamination in Great Lakes sediments using benthic invertebrate communities and the sediment quality triad approach

    USGS Publications Warehouse

    Canfield, Timothy J.; Dwyer, F. James; Fairchild, James F.; Haverland, Pamela S.; Ingersoll, Christopher G.; Kemble, Nile E.; Mount, David R.; La Point, Thomas W.; Burton, G. Allen; Swift, M. C.

    1996-01-01

    Sediments in many Great Lakes harbors and tributary rivers are contaminated. As part of the USEPA's Assessment and Remediation of Contaminated Sediment (ARCS) program, a number of studies were conducted to determine the nature and extent of sediment contamination in Great Lakes Areas of Concern (AOC). This paper describes the composition of benthic invertebrate communities in contaminated sediments and is one in a series of papers describing studies conducted to evaluate sediment toxicity from three AOC's (Buffalo River, NY; Indiana Harbor, IN; Saginaw River, MI), as part of the ARCS Program. Oligochaeta (worms) and Chironomidae (midge) comprised over 90% of the benthic invertebrate numbers in samples collected from depositional areas. Worms and midge consisted of taxa identified as primarily contaminant tolerant organisms. Structural deformities of mouthparts in midge larvae were pronounced in many of the samples. Good concurrence was evident between measures of laboratory toxicity, sediment contaminant concentration, and benthic invertebrate community composition in extremely contaminated samples. However, in moderately contaminated samples, less concordance was observed between the benthos community composition and either laboratory toxicity test results or sediment contaminant concentration. Laboratory sediment toxicity tests may better identify chemical contamination in sediments than many commonly used measures of benthic invertebrate community composition. Benthic measures may also reflect other factors such as habitat alteration. Evaluation of non-contaminant factors are needed to better interpret the response of benthic invertebrates to sediment contamination.

  18. A molecular-based approach for examining responses of eukaryotes in microcosms to contaminant-spiked estuarine sediments.

    PubMed

    Chariton, Anthony A; Ho, Kay T; Proestou, Dina; Bik, Holly; Simpson, Stuart L; Portis, Lisa M; Cantwell, Mark G; Baguley, Jeffrey G; Burgess, Robert M; Pelletier, Marguerite M; Perron, Monique; Gunsch, Claudia; Matthews, Robin A

    2014-02-01

    Ecotoxicological information for most contaminants is limited to a small number of taxa, and these are generally restricted to comparatively hardy organisms that are readily extractable from test media and easily identifiable. Advances in DNA sequencing can now provide a comprehensive view of benthic invertebrate diversity. The authors applied 454 pyrosequencing to examine the responses of benthic communities in microcosms exposed to sediments with elevated concentrations of triclosan, the endpoint being eukaryl communities that have successfully vertically migrated through the manipulated sediments. The biological communities associated with the 3 treatments (control triclosan, low triclosan [14 mg/kg], and high triclosan [180 mg/kg]) clustered into 3 groups: control/low (n = 6 controls and 4 low), moderate (n = 2 low), and high (n = 5 high). One sample was discarded as an outlier. The most pronounced change as a response to triclosan was the loss of number of metazoan operational taxonomic units (OTUs), indicative of the control/low and moderate groups, with this being most evident in the range of taxa associated with the classes Chromadorea and Bivalvia and the phylum Kinorhyncha. The authors also describe a range of other taxa that aided discrimination between the groups; compare findings with traditionally obtained meio- and macrofaunal communities obtained from the same experiment; and illustrate some of the advantages and limitations associated with both the molecular and traditional approaches. The described approach illustrates the capacity for amplicon sequencing to provide ecologically relevant information that can be used to strengthen an understanding of how sedimentary communities respond to a range of environmental stressors. © 2014 SETAC.

  19. Microbial community transitions across the deep sediment-basement interface

    NASA Astrophysics Data System (ADS)

    Labonté, J.; Lever, M. A.; Orcutt, B.

    2015-12-01

    Previous studies of microbial abundance and geochemistry in deep marine sediments indicate a stimulation of microbial activity near the sediment-basement interface; yet, the extent to which microbial communities in bottom sediments and underlying crustal habitats interact is unclear. We conducted tag pyrosequencing on DNA extracted from a spectrum of deep sediment-basement samples to try to identify patterns in microbial community shifts across sediment-basement interfaces, focusing on samples from the subsurface of the Juan de Fuca Ridge flank (IODP Expedition 327). Our results demonstrate that sediment and the basaltic crust harbor microbial communities that are phylogenetically connected, but the eveness is characteristic of the environment. We will discuss the microbial community transitions that occur horizontally along fluid flow pathways and vertically across the sediment basement interface, as well as the possible implications regarding the controls of microbial community composition along deep sediment-basement interfaces in hydrothermal systems. We will also highlight efforts to overcome sample contamination in crustal subsurface samples.

  20. Fitting response models of benthic community structure to abiotic variables in a polluted estuarine system

    NASA Astrophysics Data System (ADS)

    González-Oreja, José Antonio; Saiz-Salinas, José Ignacio

    1999-07-01

    Models of the macrozoobenthic community responses to abiotic variables measured in the polluted Bilbao estuary were obtained by multiple linear regression analyses. Total, Oligochaeta and Nematoda abundance and biomass were considered as dependent variables. Intertidal level, dissolved oxygen at the bottom of the water column (DOXB) and organic content of the sediment were selected by the analyses as the three principal explanatory variables. Goodness-of-fit of the models was high ( overlinex=71.3% ). Total abundance and biomass increased as a linear function of DOXB. The principal outcome of the vast sewage scheme currently in progress in the study area is an important contributor of increasing DOXB levels. The models exposed in this paper will serve as a tool to evaluate the expected changes in the near future.

  1. Tidal fluxes of nutrients and suspended sediments at the North Inlet Winyah Bay National Estuarine Research Reserve

    NASA Astrophysics Data System (ADS)

    Gardner, L. R.; Kjerfve, B.

    2006-12-01

    Beginning June of 1993 suites of 13 water samples have been collected at Oyster Landing, North Inlet (SC), every 20 days covering two consecutive tidal cycles at 2.07 h intervals. In order to ascertain whether this large (and still growing) water chemistry data set can be used to determine tidal fluxes of nutrients and sediments, we coupled measured concentrations to estimates of instantaneous tidal discharge based on a basin water storage curve and hindcast tides. The mean advective fluxes of all constituents, including salt, showed statistically significant exports. This result, however, is largely due to an ebb bias in the sampling protocol, which resulted in 52% of the samples being collected on ebb tide versus a theoretical percentage of 48%. When this bias was corrected by reducing the mean discharge (-610 l s -1) to a value (-125 l s -1) that produced a balance between the mean advective and dispersive salt fluxes, the advective fluxes of the other constituents were reduced to values that are not significantly different from zero. In addition to a statistically significant dispersive influx of salt, significant dispersive exports were found for DON, NH 4, DOP, PO 4 and DOC. All particulate constituents (PN, PP, ISS and OSS) yielded dispersive fluxes that were not significantly different from zero. Annual material budgets for the Oyster Landing basin based on the dispersive fluxes of all constituents (except salt) are generally similar in magnitude and direction to those measured by [Dame, R.F., Spurrier, J.D., Williams, T.M., Kjerfve, B., Zingmark, R.G., Wolaver, T.G., Chrzanowski, T.H., McKeller, H.N., Vernberg, F.J., 1991. Annual material processing by a salt marsh-estuarine basin in South Carolina, USA. Marine Ecology Progress Series 72, 153-166.] in the nearby and ecologically similar Bly Creek basin, indicating that the dispersive fluxes determined in this study are realistic. We offer suggestions for improving the reliability and usefulness of future

  2. Impact assessment of non-indigenous jellyfish species on the estuarine community dynamic: A model of medusa phase

    NASA Astrophysics Data System (ADS)

    Muha, Teja Petra; Teodósio, Maria Alexandra; Ben-Hamadou, Radhouan

    2017-03-01

    Non-indigenous jellyfish species (NIJS) Blackforida virginica have recently been introduced to the Guadiana Estuary. A modelling approach was used for the assessment of the species-specific impact on the native community, during the medusa phase. The novel interactions between NIJS and the native community are assessed through biomass variation including hydrodynamic and climatic variables. Sensitivity analysis shows that both native species, as well as NIJS highly depend on the water discharge regime, nutrient contribution and the amount of detritus production. Abiotic factors such as the Northern Atlantic Oscillation, water discharge, nutrient load and detritus production are the most influential factors for the dynamics of the estuarine ecosystem demonstrated by the model. Low water discharge and low nutrient retention rate appear to be the most favourable conditions for B. virginica. The species is a non-selective predator able to integrate into the system effectively and has caused a decrease in the biomass of other organisms in the estuarine ecosystem throughout the summer after dam removal. The B. virginica significant impact can be evaluated only when the jellyfish detritus food pathway is involved. The B. virginica predatory impact potential, as well as food preference, appears to be the most influential factors for the overall biomass variation. On the contrary, winter freshwater pulses reduce the survival rate of jellyfish polyps which results in a decrease of medusa during summer. The model presents a strong ecohydrology movement where the fluctuation of organism biomass strongly depends on the hydrological conditions including the amount of nutrient load.

  3. Evaluation of the organic matter sources using the δ13C composition of individual n-alkanes in sediments from Brazilian estuarine systems by GC/C/IRMS

    NASA Astrophysics Data System (ADS)

    Maioli, Otávio Luiz Gusso; de Oliveira, Cristiane Rossi; Dal Sasso, Marco Aurélio; Madureira, Luiz Augusto dos Santos; Azevedo, Débora de Almeida; de Aquino Neto, Francisco Radler

    2012-12-01

    The δ13C composition of individual n-alkanes (from C16 to C34) was measured from surface sediments of five Brazilian estuarine systems affected by different organic matter sources, such as harbor area, industries, urban centers and sugar cane crops, in order to determine the origins of the organic matter. The aliphatic hydrocarbon fraction was analyzed by gas chromatography-combustion-isotope ratio mass spectrometry (GC/C/IRMS). The levels of n-alkanes in the studied areas ranged from 0.34 to 18.14 μg kg-1, being relatively low in comparison to high polluted environments. The Carbon Preference Index (CPI) calculated in the C23-C34 range indicates that n-alkanes are mainly inherited from cuticular waxes of higher plants. The δ13C composition of all n-alkanes detected in the sediment samples ranged from -39.6 to -18.3‰ showing different sources for the studied estuarine systems. Through Principal Component Analysis (PCA) it was possible to verify the petrogenic influence in the n-alkane sources, especially in the Paraíba do Sul sediment samples. Differences up to 15‰ of the δ13C values between n-alkanes of odd and even carbon number (C26 and C27) also indicated mixture of petrogenic and biogenic sources in Paraíba do Sul River. High (less negative) δ13C n-alkane values of odd carbon number were obtained from two sampling sites located close to an ethanol plant, indicating residues discharge of sugar cane (C4 plant). Influence of C3 plants that are the main components of dense ombrophile forest was observed in the Itajaí-Açu sediments by the decrease of δ13C (about 10‰ compared to the Paraíba do Sul River δ13C).

  4. Speciation and fate of trace metals in estuarine sediments under reduced and oxidized conditions, Seaplane Lagoon, Alameda Naval Air Station (USA)

    PubMed Central

    Carroll, Susan; O'Day, Peggy A; Esser, Brad; Randall, Simon

    2002-01-01

    We have identified important chemical reactions that control the fate of metal-contaminated estuarine sediments if they are left undisturbed (in situ) or if they are dredged. We combined information on the molecular bonding of metals in solids from X-ray absorption spectroscopy (XAS) with thermodynamic and kinetic driving forces obtained from dissolved metal concentrations to deduce the dominant reactions under reduced and oxidized conditions. We evaluated the in situ geochemistry of metals (cadmium, chromium, iron, lead, manganese and zinc) as a function of sediment depth (to 100 cm) from a 60 year record of contamination at the Alameda Naval Air Station, California. Results from XAS and thermodynamic modeling of porewaters show that cadmium and most of the zinc form stable sulfide phases, and that lead and chromium are associated with stable carbonate, phosphate, phyllosilicate, or oxide minerals. Therefore, there is minimal risk associated with the release of these trace metals from the deeper sediments contaminated prior to the Clean Water Act (1975) as long as reducing conditions are maintained. Increased concentrations of dissolved metals with depth were indicative of the formation of metal HS- complexes. The sediments also contain zinc, chromium, and manganese associated with detrital iron-rich phyllosilicates and/or oxides. These phases are recalcitrant at near-neutral pH and do not undergo reductive dissolution within the 60 year depositional history of sediments at this site. The fate of these metals during dredging was evaluated by comparing in situ geochemistry with that of sediments oxidized by seawater in laboratory experiments. Cadmium and zinc pose the greatest hazard from dredging because their sulfides were highly reactive in seawater. However, their dissolved concentrations under oxic conditions were limited eventually by sorption to or co-precipitation with an iron (oxy)hydroxide. About 50% of the reacted CdS and 80% of the reacted ZnS were

  5. Elemental composition, distribution and control of biogenic silica in the anthropogenically disturbed and pristine zone inter-tidal sediments of Indian Sundarbans mangrove-estuarine complex.

    PubMed

    Dhame, Shreya; Kumar, Alok; Ramanathan, Al; Chaudhari, Punarbasu

    2016-10-15

    Spatial distribution and interrelationship among organic nutrients - silica and carbon - and various lithogenic elements were investigated in the surficial sediments of Matla estuary and Core Zone of Indian Sundarbans Reserve Forest using spatial analysis and multivariate statistics. Biogenic silica (BSi), an important parameter for coastal biogeochemisry, was measured using Si-time alkaline leaching method. BSi concentration ranged from 0.01% to 0.85% with higher concentrations in upstream region of Matla estuary and attenuated values towards the bay, seemingly due to changes in hydrodynamics and land use conditions. Spatial distribution of BSi did not exhibit significant correlation with sediment parameters of organic carbon (OC), elemental composition and clay content. However, it showed significant contrasting trends with total phosphorus (TP) and total silica of human influenced Matla estuary sediments as well as the dissolved silica (DSi) of its surface waters. Anthropogenic influence on sediment geochemistry is discernable with the presence of higher concentrations of organic and inorganic elements in Matla estuary than in Core Zone sediments. Spatial variation trends are often challenging to interpret due to multiple sources of input, varying energy and salinity conditions and constant physical, chemical and biological alterations occurring in the environment. Nonetheless, it is certain that anthropogenic activities have a substantial influence on biogeochemical processes of Sundarbans mangrove-estuarine complex and potentially the coastal ocean. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. A method to assess the evolution and recovery of heavy metal pollution in estuarine sediments: Past history, present situation and future perspectives.

    PubMed

    Bárcena, Javier F; Claramunt, Inigo; García-Alba, Javier; Pérez, María Luisa; García, Andrés

    2017-08-11

    A methodology to assess the historical evolution and recovery of heavy metal pollution in estuarine sediments was developed and is presented here. This approach quantifies the distribution of heavy metals in sediment cores, and investigates the influence of anthropogenic activities and/or core locations on the heavy metal pollution, by proposing and using sediment quality indices and polynomial regressions. The method has been applied to the Suances Estuary confirming its suitability as a comprehensive and practical management tool. In this estuary, the evolution of heavy metal pollution (since 1997-1998 to 2015) pointed out the deeper the sediments, the more polluted, indicating a recovery at the upper layers due to the closure and ending of washing discharges from mining, and the reduction of metal loads from industrial wastewaters. In terms of global pollution, the intertidal and subtidal sediments will require 43.1±2.8 and 8.6±0.6years to be unpolluted, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Seasonal sediment dynamics shape temperate bedrock reef communities

    USGS Publications Warehouse

    Figurski, Jared D.; Freiwald, Jan; Lonhart, Steve I.; Storlazzi, Curt

    2016-01-01

    Mobilized seafloor sediment can impact benthic reef communities through burial, scour, and turbidity. These processes are ubiquitous in coastal oceans and, through their influence on the survival, fitness, and interactions of species, can alter the structure and function of benthic communities. In northern Monterey Bay, California, USA, as much as 30% of the seafloor is buried or exposed seasonally, making this an ideal location to test how subtidal temperate rocky reef communities vary in the presence and absence of chronic sediment-based disturbances. Designated dynamic plots were naturally inundated by sediment in summer (50 to 100% cover) and swept clean in winter, whereas designated stable plots remained free of sediment during our study. Multivariate analyses indicated significant differences in the structure of sessile and mobile communities between dynamic and stable reef habitats. For sessile species, community structure in disturbed plots was less variable in space and time than in stable plots due to the maintenance of an early successional state. In contrast, community structure of mobile species varied more in disturbed plots than in stable plots, reflecting how mobile species distribute in response to sediment dynamics. Some species were found only in these disturbed areas, suggesting that the spatial mosaic of disturbance could increase regional diversity. We discuss how the relative ability of species to tolerate disturbance at different life history stages and their ability to colonize habitat translate into community-level differences among habitats, and how this response varies between mobile and sessile communities.

  8. Comparison of methods for the removal of organic carbon and extraction of chromium, iron and manganese from an estuarine sediment standard and sediment from the Calcasieu River estuary, Louisiana, U.S.A.

    USGS Publications Warehouse

    Simon, N.S.; Hatcher, S.A.; Demas, C.

    1992-01-01

    U.S. National Bureau of Standards (NBS) estuarine sediment 1646 from the Chesapeake Bay, Maryland, and surface sediment collected at two sites in the Calcasieu River estuary, Louisiana, were used to evaluate the dilute hydrochloric acid extraction of Cr, Fe and Mn from air-dried and freeze-dried samples that had been treated by one of three methods to remove organic carbon. The three methods for the oxidation and removal of organic carbon were: (1) 30% hydrogen peroxide; (2) 30% hydrogen peroxide plus 0.25 mM pyrophosphate; and (3) plasma oxidation (low-temperature ashing). There was no statistically significant difference at the 95% confidence level between air- and freeze-dried samples with respect to the percent of organic carbon removed by the three methods. Generally, there was no statistically significant difference at the 95% confidence level between air- and freeze-dried samples with respect to the concentration of Cr, Fe and Mn that was extracted, regardless of the extraction technique that was used. Hydrogen peroxide plus pyrophosphate removed the most organic carbon from sediment collected at the site in the Calcasieu River that was upstream from industrial outfalls. Plasma oxidation removed the most organic carbon from the sediment collected at a site in the Calcasieu River close to industrial outfalls and from the NBS estuarine sediment sample. Plasma oxidation merits further study as a treatment for removal of organic carbon. Operational parameters can be chosen to limit the plasma oxidation of pyrite which, unlike other Fe species, will not be dissolved by dilute hydrochloric acid. Preservation of pyrite allows the positive identification of Fe present as pyrite in sediments. ?? 1992.

  9. Effects of Actinomycete Secondary Metabolites on Sediment Microbial Communities.

    PubMed

    Patin, Nastassia V; Schorn, Michelle; Aguinaldo, Kristen; Lincecum, Tommie; Moore, Bradley S; Jensen, Paul R

    2017-02-15

    Marine sediments harbor complex microbial communities that remain poorly studied relative to other biomes such as seawater. Moreover, bacteria in these communities produce antibiotics and other bioactive secondary metabolites, yet little is known about how these compounds affect microbial community structure. In this study, we used next-generation amplicon sequencing to assess native microbial community composition in shallow tropical marine sediments. The results revealed complex communities comprised of largely uncultured taxa, with considerable spatial heterogeneity and known antibiotic producers comprising only a small fraction of the total diversity. Organic extracts from cultured strains of the sediment-dwelling actinomycete genus Salinispora were then used in mesocosm studies to address how secondary metabolites shape sediment community composition. We identified predatory bacteria and other taxa that were consistently reduced in the extract-treated mesocosms, suggesting that they may be the targets of allelopathic interactions. We tested related taxa for extract sensitivity and found general agreement with the culture-independent results. Conversely, several taxa were enriched in the extract-treated mesocosms, suggesting that some bacteria benefited from the interactions. The results provide evidence that bacterial secondary metabolites can have complex and significant effects on sediment microbial communities.

  10. Sediment microbial community composition and methylmercury pollution at four mercury mine-impacted sites.

    PubMed

    Batten, K M; Scow, K M

    2003-11-01

    Mercury pollution presents a globally significant threat to human and ecosystem health. An important transformation in the mercury cycle is the conversion of inorganic mercury to methylmercury, a toxic substance that negatively affects neurological function and bioaccumulates in food chains. This transformation is primarily bacterially mediated, and sulfate-reducing bacteria (SRB) have been specifically implicated as key mercury methylators in lake and estuarine sediments. This study used phospholipid fatty acid (PLFA) analysis to investigate sediment microbial community composition at four abandoned mercury mine-impacted sites in the California Coast Range: the Abbott, Reed, Sulphur Bank, and Mt. Diablo mines. Differences in watershed and hydrology among these sites were related to differences in microbial community composition. The Abbott and Sulphur Bank mines had the highest levels of methylmercury. Floc (a type of precipitate that forms when acid mine drainage contacts lake or river water) and sediment samples differed in terms of several important environmental variables and microbial community composition, but did not have statistically different methylmercury concentrations. Quantification of PLFA biomarkers for SRB (10Mel6:0 for Desulfobacter and i17:1 for Desulfovibrio) revealed that Desulfobacter and Desulfovibrio organisms made up higher percentages of overall microbial biomass at the Sulphur Bank and Mt. Diablo mines than at the Abbott and Reed mines. Correlations between these SRB biomarker fatty acids and methylmercury concentrations suggest that Desulfobacter and Desulfovibrio organisms may contribute to methylmercury production in the Abbott, Reed, and Sulphur Bank mines but may not be important contributors to methylmercury in the Mt. Diablo Mine.

  11. Hydrocarbon pollutants shape bacterial community assembly of harbor sediments.

    PubMed

    Barbato, Marta; Mapelli, Francesca; Magagnini, Mirko; Chouaia, Bessem; Armeni, Monica; Marasco, Ramona; Crotti, Elena; Daffonchio, Daniele; Borin, Sara

    2016-03-15

    Petroleum pollution results in co-contamination by different classes of molecules, entailing the occurrence of marine sediments difficult to remediate, as in the case of the Ancona harbor (Mediterranean Sea, Italy). Autochthonous bioaugmentation (ABA), by exploiting the indigenous microbes of the environment to be treated, could represent a successful bioremediation strategy. In this perspective we aimed to i) identify the main drivers of the bacterial communities' richness in the sediments, ii) establish enrichment cultures with different hydrocarbon pollutants evaluating their effects on the bacterial communities' composition, and iii) obtain a collection of hydrocarbon degrading bacteria potentially exploitable in ABA. The correlation between the selection of different specialized bacterial populations and the type of pollutants was demonstrated by culture-independent analyses, and by establishing a collection of bacteria with different hydrocarbon degradation traits. Our observations indicate that pollution dictates the diversity of sediment bacterial communities and shapes the ABA potential in harbor sediments.

  12. Estuarine modification of nutrient and sediment exports to the Great Barrier Reef Marine Park from the Daintree and Annan River catchments.

    PubMed

    Davies, Peter L; Eyre, Bradley D

    2005-01-01

    Nutrient and suspended sediment concentrations were measured in the dry season and during the rising and falling stages of flood events in the Annan and Daintree rivers to estimate catchment exports. These flood events were also sampled along the salinity gradient in the estuary and nearshore shelf to quantify the modification of terrestrial sediment and nutrient loads as they pass through estuaries into the Great Barrier Reef lagoon. In the Daintree River TSS concentrations were found to increase between the catchment and the estuary plume. The source of TSS may have been scour of the estuarine channel or from land use in the catchment of the lower estuary. In the dry season nitrogen enters the Annan and Daintree estuaries predominantly in the form of PON and DON in roughly equal proportions. Nitrogen exports to the GBR are mostly in the form of DON. In the wet season the majority of nitrogen enters the estuaries as DON and leaves as PON. Nitrogen removal in the estuaries and plumes appears to be biologically mediated once suspended sediment concentrations decrease to a point where phytoplankton growth is not light limited. In the dry season phosphorus enters and leaves the estuaries primarily in organic form. PIP is the dominant form of phosphorus in river water, but leaves the estuary more evenly distributed between all forms. These estuarine processes result in less nitrogen and phosphorus being delivered to the GBR lagoon than is exported from the catchment. The differences between these estuaries highlights the need for further work to explore modifications in estuaries that drain into the Great Barrier Reef lagoon.

  13. Disturbance of intertidal soft-sediment benthic communities by cockle hand raking

    NASA Astrophysics Data System (ADS)

    Kaiser, M. J.; Broad, G.; Hall, S. J.

    2001-05-01

    Recent awareness of the ecosystem effects of fishing activities on the marine environment means that there is a pressing need to evaluate the direct and indirect effects of those activities that may have negative effects on non-target species and habitats. The cockle, Cerastoderma edule (L.) is the target of a commercial and artisanal fishery that occurs in intertidal and estuarine habitats across Northern Europe. Cockles are harvested either mechanically using tractor dredges or suction dredges or by large numbers of individual fishers using hand rakes. This study examined the effects of hand raking on the non-target species and under-sized cockles associated with intertidal cockle beds and the effects of size of the patch of sediment disturbed on subsequent recolonisation. Hand raking led to an initial three-fold increase in the damage rate of under-sized cockles compared with control plots. The communities in both small and large raked plots showed community changes relative to control plots 14 days after the initial disturbance. The small raked plots had recovered 56 days after the initial disturbance whereas the large raked plots remained in an altered state. Samples collected over a year later indicated that small-scale variations in habitat heterogeneity had been altered and suggest that while effects of hand raking may be significant within a year, they are unlikely to persist beyond this time-scale unless there are larger long-lived species present within the community.

  14. Methodology to assess the mobility of trace elements between water and contaminated estuarine sediments as a function of the site physico-chemical characteristics.

    PubMed

    Fdez-Ortiz de Vallejuelo, Silvia; Gredilla, Ainara; de Diego, Alberto; Arana, Gorka; Madariaga, Juan Manuel

    2014-03-01

    This work presents an innovative methodology to have a rapid diagnosis about the mobility of selected trace elements of known toxicity and biological risk (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sn and Zn) present in contaminated sediments. The novel strategy presented in this work uses, therefore, the own estuarine water in contact with sediments as the extracting agent to perform the mobility tests, simulating the real situation of the estuary. This water suffers from different physico-chemical conditions (low and high tides) and gives consequently, rather better information than the one obtained by the routine sequential extraction procedures. The final step of this methodology was the use of spatial modelling by kriging method and multivariate chemometric analysis, both for a better interpretation of the results. To achieve this goal, sediment and water samples were strategically collected at eight different points (four in tributary rivers, one in a closed dock, two in the main channel and another one in the mouth) along the Nerbioi-Ibaizabal River estuary (Metropolitan Bilbao, Basque Country) approximately every three months (summer, autumn, winter and spring) during a whole year. Physico-chemical changes, such as pH, carbonate content and organic matter of the sediments, together with variations in water salinity appear to be responsible for metal mobility from the sediment to the water layer. The influence of these variables was higher in the sites located close to the sea. Moreover, the mobility of trace elements was even higher at high tide in sediments with lower metal content. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Unravelling the complex structure of a benthic community: A multiscale-multianalytical approach to an estuarine sandflat

    NASA Astrophysics Data System (ADS)

    Giménez, Luis; Dimitriadis, Caterina; Carranza, Alvar; Borthagaray, Ana Inés; Rodríguez, Marcel

    2006-07-01

    We evaluated scale-dependent patterns of distribution of sandflat macroinfauna of a coastal lagoon, using different analytical approaches. The sampled area was divided into three sectors (outer, inner-north, inner-south) containing small promontories. At each side of the promontories we defined stations in a line transect across the sandflat. Thus, we evaluated sediment characteristics and macroinfaunal responses to sectors, orientations and intertidal levels; animal-sediment relationships were also studied. At a large scale, there was a clear pattern of sediment composition and macroinfaunal abundance. While the outer sector had medium to coarse sands, reflecting the high hydrodynamic conditions existing near the lagoon entrance, the inner sectors showed sandy and muddy sediments. Most species were in low abundances at the outer sector. At small scale, macroinfaunal abundance and species richness decreased sharply towards the upper sandflat level. Also at small scale, sediment composition limited the maximal densities reached by all species, with exception of the deposit-feeding polychaetes. Thus, the macroinfaunal community at muddy sediments was dominated by burrowing deposit-feeders, while all species peaked in sandy sediments. Our results suggest that physical factors shaping macroinfaunal communities operate at different scales and are better detected using several analytical approaches. Large scale patterns, associated with along-shore variations in disturbance by currents, were detected as changes in the mean abundance of macroinfauna. Small scale patterns, related to sediment characteristics, were observed as changes in maximal densities of macroinfauna. Small scale patterns, associated with the level of inundation of the sandflats, were detected through changes in the abundance and presence of macroinfauna. The evaluation of the role of the physical conditions on communities must involve the use of several sampling and analytical approaches.

  16. Microbial community composition in sediments resists perturbation by nutrient enrichment

    PubMed Central

    Bowen, Jennifer L; Ward, Bess B; Morrison, Hilary G; Hobbie, John E; Valiela, Ivan; Deegan, Linda A; Sogin, Mitchell L

    2011-01-01

    Functional redundancy in bacterial communities is expected to allow microbial assemblages to survive perturbation by allowing continuity in function despite compositional changes in communities. Recent evidence suggests, however, that microbial communities change both composition and function as a result of disturbance. We present evidence for a third response: resistance. We examined microbial community response to perturbation caused by nutrient enrichment in salt marsh sediments using deep pyrosequencing of 16S rRNA and functional gene microarrays targeting the nirS gene. Composition of the microbial community, as demonstrated by both genes, was unaffected by significant variations in external nutrient supply in our sampling locations, despite demonstrable and diverse nutrient-induced changes in many aspects of marsh ecology. The lack of response to external forcing demonstrates a remarkable uncoupling between microbial composition and ecosystem-level biogeochemical processes and suggests that sediment microbial communities are able to resist some forms of perturbation. PMID:21412346

  17. Microbial community composition in sediments resists perturbation by nutrient enrichment.

    PubMed

    Bowen, Jennifer L; Ward, Bess B; Morrison, Hilary G; Hobbie, John E; Valiela, Ivan; Deegan, Linda A; Sogin, Mitchell L

    2011-09-01

    Functional redundancy in bacterial communities is expected to allow microbial assemblages to survive perturbation by allowing continuity in function despite compositional changes in communities. Recent evidence suggests, however, that microbial communities change both composition and function as a result of disturbance. We present evidence for a third response: resistance. We examined microbial community response to perturbation caused by nutrient enrichment in salt marsh sediments using deep pyrosequencing of 16S rRNA and functional gene microarrays targeting the nirS gene. Composition of the microbial community, as demonstrated by both genes, was unaffected by significant variations in external nutrient supply in our sampling locations, despite demonstrable and diverse nutrient-induced changes in many aspects of marsh ecology. The lack of response to external forcing demonstrates a remarkable uncoupling between microbial composition and ecosystem-level biogeochemical processes and suggests that sediment microbial communities are able to resist some forms of perturbation.

  18. Examination of factors dominating the sediment-water diffusion flux of DDT-related compounds measured by passive sampling in an urbanized estuarine bay.

    PubMed

    Feng, Yan; Wu, Chen-Chou; Bao, Lian-Jun; Shi, Lei; Song, Lin; Zeng, Eddy Y

    2016-12-01

    The fate of hydrophobic organic compounds in aquatic environment are largely determined by their exchange at sediment-water interface, which is highly dynamic and subject to rapidly evolving environmental conditions. In turn, environmental conditions may be governed by both physicochemical parameters and anthropogenic events. To examine the importance of various impact factors, passive sampling devices were deployed at the seafloor of Hailing Bay, an urbanized estuarine bay in Guangdong Province of South China to measure the sediment-water diffusion fluxes of several metabolites of dichlorodiphenyltrichloroethane (DDT), p,p'-DDE, p,p'-DDD and o,p'-DDD. The physicochemical properties of water (temperature, pH, salinity and dissolved oxygen) and surface sediment (sediment organic matter, physical composition, pH, water content, colony forming unit and catalase activity) were also measured. The results showed that the diffusion fluxes of o,p'-DDD, p,p'-DDD and p,p'-DDE at sites A1 and A2 near a fishing boat maintenance facility ranged from 0.42 to 4.73 ng m(-2) d(-1) (from sediment to overlying water), whereas those at offshore sites varied between -0.03 and -3.02 ng m(-2) d(-1) (from overlying water to sediment), implicating A1 and A2 as the sources of the target compounds. The distribution patterns of the diffusion fluxes of the target compounds were different from those of water and sediment parameters (water temperature, salinity, sediment texture, pH, colony forming unit and catalase activity) at six sampling sites. This finding suggested that none of these parameters were critical in dictating the sediment-water diffusion fluxes. Besides, decreases in the contents of kerogen and black carbon by 6.7% and 11% would enhance the diffusion fluxes of the target compounds by 11-14% and 12-23%, respectively, at site A1, indicating that kerogen and black carbon were the key factors in mediating the sediment-water diffusion fluxes of DDT-related compounds in field

  19. Diversity of urea-degrading microorganisms in open-ocean and estuarine planktonic communities.

    PubMed

    Collier, Jackie L; Baker, Kristopher M; Bell, Sheryl L

    2009-12-01

    Urea is an important and dynamic natural component of marine nitrogen cycling and also a major contributor to anthropogenic eutrophication of coastal ecosystems, yet little is known about the identities or diversity of ureolytic marine microorganisms. Primers targeting the gene encoding urease were used to PCR-amplify, clone and sequence 709 urease gene fragments from 31 plankton samples collected at both estuarine and open-ocean locations. Two hundred and eighty-six amplicons belonged to 22 distinct sequence types that were closely enough related to named organisms to be identified, and included urease sequences both from typical marine planktonic organisms and from bacteria usually associated with terrestrial habitats. The remaining 423 amplicons were not closely enough related to named organisms to be identified, and belonged to 96 distinct sequence types of which 43 types were found in two or more different samples. The distributions of unidentified urease sequence types suggested that some represented truly marine microorganisms while others reflected terrestrial inputs to low-salinity estuarine areas. The urease primers revealed this great diversity of ureolytic organisms because they were able to amplify many previously unknown, environmentally relevant urease genes, and they will support new approaches for exploring the role of urea in marine ecosystems.

  20. Metabolically active microbial communities in uranium-contaminated subsurface sediments.

    PubMed

    Akob, Denise M; Mills, Heath J; Kostka, Joel E

    2007-01-01

    In order to develop effective bioremediation strategies for radionuclide contaminants, the composition and metabolic potential of microbial communities need to be better understood, especially in highly contaminated subsurface sediments for which little cultivation-independent information is available. In this study, we characterized metabolically active and total microbial communities associated with uranium-contaminated subsurface sediments along geochemical gradients. DNA and RNA were extracted and amplified from four sediment-depth intervals representing moderately acidic (pH 3.7) to near-neutral (pH 6.7) conditions. Phylotypes related to Proteobacteria (Alpha-, Beta-, Delta- and Gammaproteobacteria), Bacteroidetes, Actinobacteria, Firmicutes and Planctomycetes were detected in DNA- and RNA-derived clone libraries. Diversity and numerical dominance of phylotypes were observed to correspond to changes in sediment geochemistry and rates of microbial activity, suggesting that geochemical conditions have selected for well-adapted taxa. Sequences closely related to nitrate-reducing bacteria represented 28% and 43% of clones from the total and metabolically active fractions of the microbial community, respectively. This study provides the first detailed analysis of total and metabolically active microbial communities in radionuclide-contaminated subsurface sediments. Our microbial community analysis, in conjunction with rates of microbial activity, points to several groups of nitrate-reducers that appear to be well adapted to environmental conditions common to radionuclide-contaminated sites.

  1. Distribution of nitrogenous nutrients and denitrifiers strains in estuarine sediment profiles of the Tanshui River, northern Taiwan

    NASA Astrophysics Data System (ADS)

    Fan, L. F.; Shieh, W. Y.; Wu, W. F.; Chen, C.-P.

    2006-09-01

    Chemical profiles of both oxidized (nitrate and sulfate) and reduced (ammonium, sulfide, acid-volatile sulfide [AVS], and pyrite) materials and the corresponding distribution of denitrifier microbial communities were measured at low tide in sediments at Guandu in the estuary of the Tanshui River, northern Taiwan in August 2002. Denitrifier strains were isolated for physiological and phylogenic analyses. Based on the distribution of nitrogenous compounds and denitrifier abundances, the vertical profile of Guandu sediments could be separated into four layers: a mixed layer (the top 1 cm of depth, respectively containing 0.82-2.37 and 535.9-475.0 μM of nitrate and ammonium), a nitrate-concentrated layer (1-5 cm in depth, 2.37-0.53 and 475.0-1192.1 μM, respectively), a denitrifier-aggregation layer (5-7 cm in depth, 0.53-0.72 and 1192.1-1430.1 μM, respectively), and an ammonium-enriched layer (7-12 cm in depth, 0.72-0.78 and 1430.1-2196.6 μM, respectively). Denitrifier strains were detected in all layers except for the mixed layer. A variety of metabolic processes by these strains may occur in different layers. Bacillus jeotgali-, Bacillus sphaericus-, and Bacillus firmus-related strains isolated from the nitrate-concentrated layer may be involved in the nitrification-denitrification coupling process due to the relatively low nitrate concentrations (maximum = 2.37 μM), and may contribute to denitrification not nitrification. Bacillus bataviensis- and B. jeotgali-related strains isolated from the denitrifier-aggregation layer comprised the predominant denitrifier population (3.64 × 10 4 cells/g of denitrifier abundance). They possess the ability of dissimilatory nitrate reduction to ammonium (DNRA). Bacillus jeotgali-related strains and two newly identified strains of GD0705 and GD0706 isolated from the ammonium-enriched layer possibly use fermentative processes as the main metabolic pathway instead of denitrification when nitrate is scarce, and this further

  2. Avoidance response of the estuarine amphipod Eohaustorius estuarius to polycyclic aromatic hydrocarbon-contaminated, field-collected sediments

    SciTech Connect

    Kravitz, M.J. . Office of Water); Lamberson, J.O.; Ferraro, S.P.; Swartz, R.C.; Boese, B.L.; Specht, D.T. )

    1999-06-01

    Amphipods (Eohaustorius estuarius) were placed in two-chamber containers with different combinations of three contaminated sediments and a control sediment, and their distribution was determined after 2 or 3 d. Amphipods avoided the sediment with the highest PAH contamination and one of two sediments with moderate PAH concentrations. In the moderately contaminated sediment avoided by amphipods, the (avoidance) response was more sensitive than mortality as a biological indicator of unacceptable sediment contamination. The avoidance response in this case likely represents an early indication of potential mortality from sediment exposure. Population levels of amphipods in moderately to heavily PAH-contaminated sediments may be influenced by a combination of avoidance behavior and toxicity/lethality.

  3. Short-term enhancement and long-term suppression of denitrification in estuarine sediments receiving primary- and secondary-treated paper and pulp mill discharge.

    PubMed

    Oakes, Joanne M; Eyre, Bradley D; Ross, Donald J

    2011-04-15

    To determine the role of sediment denitrification in removing inputs of primary- (PE) and secondary-treated effluent (SE) from a pulp and paper mill (PPM), organic matter (OM) associated with PE (residual wood fiber) and SE (activated sludge biomass and phytoplankton) was added to estuarine intertidal sediments and denitrification rates were measured over 27 days. Labile sludge biomass and phytoplankton initially stimulated denitrification, including for pre-existing sediment N. After 2.5 d, however, denitrification was suppressed apparently due to microbial competition for N to process the refractory (high C:N) material remaining. Wood fiber suppressed denitrification throughout the experiment due to competition for N to process the refractory OM. Ultimate long-term denitrification suppression by phytoplankton is offset by initial enhanced denitrification rates. Although nutrient release during degradation of sludge biomass and wood fiber may stimulate phytoplankton production, N equivalent to 127% of the expected daily phytoplankton load was denitrified within 24 h, allowing for permanent removal of PPM-derived N. Compared to primary treatment, secondary treatment of PPM effluent has greater potential for N removal.

  4. STORAGE DURATION AND TEMPERATURE AND THE ACUTE TOXICITIES OF ESTUARINE SEDIMENTS TO MYSIDOPSIS BAHIA AND LEPTOCHEIRUS PLUMULOSUS

    EPA Science Inventory

    Many statutory needs for sediment quality assessment exist (U.S. EPA 1996). A variety of sediment toxicity tests have been used to support the development of sediment quality guidelines and to determine the benthic impacts of dredging activities and point and non-point source tox...

  5. STORAGE DURATION AND TEMPERATURE AND THE ACUTE TOXICITIES OF ESTUARINE SEDIMENTS TO MYSIDOPSIS BAHIA AND LEPTOCHEIRUS PLUMULOSUS

    EPA Science Inventory

    Many statutory needs for sediment quality assessment exist (U.S. EPA 1996). A variety of sediment toxicity tests have been used to support the development of sediment quality guidelines and to determine the benthic impacts of dredging activities and point and non-point source tox...

  6. Human and Environmental Impacts on River Sediment Microbial Communities

    DOE PAGES

    Gibbons, Sean M.; Jones, Edwin; Bearquiver, Angelita; ...

    2014-05-19

    Sediment microbial communities are responsible for a majority of the metabolic activity in river and stream ecosystems. Understanding the dynamics in community structure and function across freshwater environments will help us to predict how these ecosystems will change in response to human land-use practices. Here we present a spatiotemporal study of sediments in the Tongue River (Montana, USA), comprising six sites along 134 km of river sampled in both spring and fall for two years. Sequencing of 16S rRNA amplicons and shotgun metagenomes revealed that these sediments are the richest (~65,000 microbial ‘species’ identified) and most novel (93% of OTUsmore » do not match known microbial diversity) ecosystems analyzed by the Earth Microbiome Project to date, and display more functional diversity than was detected in a recent review of global soil metagenomes. Community structure and functional potential have been significantly altered by anthropogenic drivers, including increased pathogenicity and antibiotic metabolism markers near towns and metabolic signatures of coal and coalbed methane extraction byproducts. The core (OTUs shared across all samples) and the overall microbial community exhibited highly similar structure, and phylogeny was weakly coupled with functional potential. Together, these results suggest that microbial community structure is shaped by environmental drivers and niche filtering, though stochastic assembly processes likely play a role as well. These results indicate that sediment microbial communities are highly complex and sensitive to changes in land use practices.« less

  7. Human and Environmental Impacts on River Sediment Microbial Communities

    SciTech Connect

    Gibbons, Sean M.; Jones, Edwin; Bearquiver, Angelita; Blackwolf, Frederick; Roundstone, Wayne; Scott, Nicole; Hooker, Jeff; Madsen, Robert; Coleman, Maureen L.; Gilbert, Jack A.

    2014-05-19

    Sediment microbial communities are responsible for a majority of the metabolic activity in river and stream ecosystems. Understanding the dynamics in community structure and function across freshwater environments will help us to predict how these ecosystems will change in response to human land-use practices. Here we present a spatiotemporal study of sediments in the Tongue River (Montana, USA), comprising six sites along 134 km of river sampled in both spring and fall for two years. Sequencing of 16S rRNA amplicons and shotgun metagenomes revealed that these sediments are the richest (~65,000 microbial ‘species’ identified) and most novel (93% of OTUs do not match known microbial diversity) ecosystems analyzed by the Earth Microbiome Project to date, and display more functional diversity than was detected in a recent review of global soil metagenomes. Community structure and functional potential have been significantly altered by anthropogenic drivers, including increased pathogenicity and antibiotic metabolism markers near towns and metabolic signatures of coal and coalbed methane extraction byproducts. The core (OTUs shared across all samples) and the overall microbial community exhibited highly similar structure, and phylogeny was weakly coupled with functional potential. Together, these results suggest that microbial community structure is shaped by environmental drivers and niche filtering, though stochastic assembly processes likely play a role as well. These results indicate that sediment microbial communities are highly complex and sensitive to changes in land use practices.

  8. Human and Environmental Impacts on River Sediment Microbial Communities

    PubMed Central

    Gibbons, Sean M.; Jones, Edwin; Bearquiver, Angelita; Blackwolf, Frederick; Roundstone, Wayne; Scott, Nicole; Hooker, Jeff; Madsen, Robert; Coleman, Maureen L.; Gilbert, Jack A.

    2014-01-01

    Sediment microbial communities are responsible for a majority of the metabolic activity in river and stream ecosystems. Understanding the dynamics in community structure and function across freshwater environments will help us to predict how these ecosystems will change in response to human land-use practices. Here we present a spatiotemporal study of sediments in the Tongue River (Montana, USA), comprising six sites along 134 km of river sampled in both spring and fall for two years. Sequencing of 16S rRNA amplicons and shotgun metagenomes revealed that these sediments are the richest (∼65,000 microbial ‘species’ identified) and most novel (93% of OTUs do not match known microbial diversity) ecosystems analyzed by the Earth Microbiome Project to date, and display more functional diversity than was detected in a recent review of global soil metagenomes. Community structure and functional potential have been significantly altered by anthropogenic drivers, including increased pathogenicity and antibiotic metabolism markers near towns and metabolic signatures of coal and coalbed methane extraction byproducts. The core (OTUs shared across all samples) and the overall microbial community exhibited highly similar structure, and phylogeny was weakly coupled with functional potential. Together, these results suggest that microbial community structure is shaped by environmental drivers and niche filtering, though stochastic assembly processes likely play a role as well. These results indicate that sediment microbial communities are highly complex and sensitive to changes in land use practices. PMID:24841417

  9. An Evaluation of Partial Digestion Protocols for the Extraction and Measurement of Trace Metals of Environmental Concern in Marine and Estuarine Sediments

    NASA Astrophysics Data System (ADS)

    Winters, S. J.; Krahforst, C.; Sherman, L.; Kehm, K.

    2013-12-01

    As part of a broad study of the fate and transport of trace metals in estuarine sediments (Krahforst et al., 2013), the efficacy of commonly-used partial digestion protocols, including ISO 11466 (treatment with aqua regia), EPA 3050B (nitric acid followed by H2O2) and a modified rock digestion method ('RD' method- H2O2 followed by nitric), were evaluated for two NIST SRM materials, marine sediment 2702 and estuarine sediment 1646a. Unlike so-called total sediment digestions, the methods studied in this work do not employ hydrofluoric acid and are thought to leave silicates substantially or wholly intact. These methods can in principle compliment studies based on total digestions by providing information about trace metals in phases that are potentially more labile in the marine environment. Samples were digested in ~150 mg aliquots. Application of ISO 11466 and EPA 3050B followed published protocols except that digestions were carried out in trace-metal clean 15 mL capped Teflon vessels in an Al block digester and, at the end of the procedure, the supernatant was decanted from undigested material following repeated centrifugation in 2% nitric acid. Digested solutions were analyzed for Al, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Ag, Cd, Sn and Pb content by ICPMS. All elements were analyzed in collision reaction cell mode to minimize isobaric interferences, except Cd and Ag, which were analyzed in standard mode. Instrument performance was monitored in-run by analyzing the SRM 1643e and several quality-check standards. Two repeated digestions of SRM 2702 and SRM 1646a using EPA 3050B produced identical yields, within the standard deviation of repeated analyses (0 - 5%), for all analyzed elements except Cu, which varied by 30% for SRM 2702. The same was true for ISO 11466, although the standard deviation of repeated analyses for this digestion series tended to be larger (< ~15%). The RD method, which consists of pre-treatment with H2O2 followed by repeated treatments with

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

    PubMed

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

    2017-04-01

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

  11. Molecular characterization of sulfate-reducing bacteria community in surface sediments from the adjacent area of Changjiang Estuary

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Zhen, Yu; Mi, Tiezhu; He, Hui; Yu, Zhigang

    2016-02-01

    Sulfate-reducing bacteria (SRB), which obtain energy from dissimilatory sulfate reduction, play a vital role in the carbon and sulfur cycles. The dissimilatory sulfite reductase (Dsr), catalyzing the last step in the sulfate reduction pathway, has been found in all known SRB that have been tested so far. In this study, the diversity of SRB was investigated in the surface sediments from the adjacent area of Changjiang Estuary by PCR amplification, cloning and sequencing of the dissimilatory sulfite reductase beta subunit gene ( dsrB). Based on dsrB clone libraries constructed in this study, diversified SRB were found, represented by 173 unique OTUs. Certain cloned sequences were associated with Desulfobacteraceae, Desulfobulbaceae, and a large fraction (60%) of novel sequences that have deeply branched groups in the dsrB tree, indicating that novel SRB inhabit the surface sediments. In addition, correlations of the SRB assemblages with environmental factors were analyzed by the linear model-based redundancy analysis (RDA). The result revealed that temperature, salinity and the content of TOC were most closely correlated with the SRB communities. More information on SRB community was obtained by applying the utility of UniFrac to published dsrB gene sequences from this study and other 9 different kinds of marine environments. The results demonstrated that there were highly similar SRB genotypes in the marine and estuarine sediments, and that geographic positions and environmental factors influenced the SRB community distribution.

  12. Interactions of Cd and Cu in anaerobic estuarine sediments. 2: Bioavailability, body burdens and respiration effects as related to geochemical partitioning

    SciTech Connect

    Rule, J.H.; Alden, R.W. III

    1996-04-01

    The relationship between Cd and Cu distribution in sediment geochemical fractions and their bioavailability was studied. A fine-sandy textured estuarine sediment was treated with all combinations of 0, 2.5, and 5 mg/kg Cd and 0, 12, and 25 mg/kg Cu using the chloride salts of each metal. Grass shrimp (Palaemonetes pugio), blue mussel (Mytilus edulis), and hard clam (Mercenaria mercenaria) were exposed to the treated sediments in aquaria with 20 ppt artificial seawater for 14 d. Sediments were sequentially extracted before and after organism exposure to determine the exchangeable, easily reducible, organic-sulfide, moderately reducible, and acid extractable phases. Low mortalities were observed for all organism types and none were attributable to any of the treatments. The Cd and Cu concentrations in the easily reducible and organic-sulfide phases were found to be significantly related to the bioavailability of these metals. The most highly significant relationship was established between Cd in the easily reducible phase and body burden of Cd in the blue mussel. Notable interactions were found between Cd and Cu in some of the geochemical phases, body burdens, and respiration rates. Metal uptake, respiration, and interactions were highly dependent on the test species. A significant correlation was found between increased body burden and depressed respiration for Cd but not for Cu. Multiple regression models are used to describe these relationships. It appears that the interactive responses in the organisms are driven primarily by the sediment geochemical effects and mediated by individual organism processes. These results underscore the necessity of multicomponent (multielement) studies in assessing the fate and effects of toxic elements in the environment.

  13. Phytoplankton diversity and community composition along the estuarine gradient of a temperate macrotidal ecosystem: combined morphological and molecular approaches.

    PubMed

    Bazin, Pauline; Jouenne, Fabien; Friedl, Thomas; Deton-Cabanillas, Anne-Flore; Le Roy, Bertrand; Véron, Benoît

    2014-01-01

    Microscopical and molecular analyses were used to investigate the diversity and spatial community structure of spring phytoplankton all along the estuarine gradient in a macrotidal ecosystem, the Baie des Veys (eastern English Channel). Taxa distribution at high tide in the water column appeared to be mainly driven by the tidal force which superimposed on the natural salinity gradient, resulting in a two-layer flow within the channel. Lowest taxa richness and abundance were found in the bay where Teleaulax-like cryptophytes dominated. A shift in species composition occurred towards the mouth of the river, with the diatom Asterionellopsis glacialis dramatically accumulating in the bottom waters of the upstream brackish reach. Small thalassiosiroid diatoms dominated the upper layer river community, where taxa richness was higher. Through the construction of partial 18S rDNA clone libraries, the microeukaryotic diversity was further explored for three samples selected along the surface salinity gradient (freshwater - brackish - marine). Clone libraries revealed a high diversity among heterotrophic and/or small-sized protists which were undetected by microscopy. Among them, a rich variety of Chrysophyceae and other lineages (e.g. novel marine stramenopiles) are reported here for the first time in this transition area. However, conventional microscopy remains more efficient in revealing the high diversity of phototrophic taxa, low in abundances but morphologically distinct, that is overlooked by the molecular approach. The differences between microscopical and molecular analyses and their limitations are discussed here, pointing out the complementarities of both approaches, for a thorough phytoplankton community description.

  14. Persistence and Growth of the Fecal Indicator Bacteria Enterococci in Detritus and Natural Estuarine Plankton Communities

    PubMed Central

    Mote, Beth L.; Turner, Jeffrey W.

    2012-01-01

    Enterococci are used to evaluate recreational-water quality and health risks in marine environments. In addition to their occurrence in feces of warm blooded animals, they are also common epiphytes. We investigated the contribution of plankton- or particle-associated enterococci in estuarine and coastal water. Seven water and size-fractionated plankton samples were collected monthly between April 2008 and January 2009 in the tidal reaches of the Skidaway River (Georgia, USA). Each size fraction, along with filtered (<30 μm) and bulk estuarine water, was processed according to U.S. Environmental Protection Agency method 1600. Presumptive enterococci were selected and species were identified using carbon substrate utilization patterns. The highest average densities occurred within the 30-, 63-, 105-, and 150-μm size fractions, which also represented the majority (>99%) of the particles within the sampled water. Particle-associated enterococci accounted for as little as 1% of enterococci in bulk water in April to as much as 95% in July. Enterococcus faecalis was the most commonly isolated species from both water and plankton and represented 31% (16/51) and 35% (6/17) of the identified Enterococcus species from water and plankton, respectively. Enterococcus casseliflavus represented 29% of the selected isolates from plankton and 16% from water. Both E. faecalis and E. casseliflavus were able to survive and grow in plankton suspensions significantly longer than in artificial seawater. Enterococcus spp. may be highly concentrated in plankton and associated particles, especially during summer and fall months. These findings could have implications for the effectiveness of enterococci as an indicator of coastal water quality, especially in particle-rich environments. PMID:22327586

  15. The Community Sediment Transport Modeling System

    DTIC Science & Technology

    2008-01-01

    structure control) within the ESMF library. This will enable volumetric coupling within the ROMS computational kernel without the need to split the...model to investigate the vertical structure of wave-supported gravity flows such as those documented by Traykovski et al. (2007) on the California...Figure 7 indicates that the model effectively captures the vertical structure of the suspended sediment distribution and the magnitude of the velocity

  16. Disturbance Increases Microbial Community Diversity and Production in Marine Sediments

    PubMed Central

    Galand, Pierre E.; Lucas, Sabrina; Fagervold, Sonja K.; Peru, Erwan; Pruski, Audrey M.; Vétion, Gilles; Dupuy, Christine; Guizien, Katell

    2016-01-01

    Disturbance strongly impacts patterns of community diversity, yet the shape of the diversity-disturbance relationship remains a matter of debate. The topic has been of interest in theoretical ecology for decades as it has practical implications for the understanding of ecosystem services in nature. One of these processes is the remineralization of organic matter by microorganisms in coastal marine sediments, which are periodically impacted by disturbances across the sediment-water interface. Here we set up an experiment to test the hypothesis that disturbance impacts microbial diversity and function during the anaerobic degradation of organic matter in coastal sediments. We show that during the first 3 weeks of the experiment, disturbance increased both microbial production, derived from the increase in microbial abundance, and diversity of the active fraction of the community. Both community diversity and phylogenetic diversity increased, which suggests that disturbance promoted the cohabitation of ecologically different microorganisms. Metagenome analysis also showed that disturbance increased the relative abundance of genes diagnostic of metabolism associated with the sequential anaerobic degradation of organic matter. However, community composition was not impacted in a systematic way and changed over time. In nature, we can hypothesize that moderate storm disturbances, which impact coastal sediments, promote diverse, and productive communities. These events, rather than altering the decomposition of organic matter, may increase the substrate turnover and, ultimately, remineralization rates. PMID:27994581

  17. CAN LANDSCAPE CHARACTERISTICS OF WATERSHEDS HELP FIND IMPAIRED ESTUARINE BOTTOM COMMUNITIES

    EPA Science Inventory

    Human alteration of watersheds and their landscapes often leads to undesirable effects in estuaries, such as excess nutrients, organic matter, and sediments, as well as increased levels of contaminants and pathogens. We hypothesized that alterations in watersheds associated wit...

  18. Sudden clearing of estuarine waters upon crossing the threshold from transport to supply regulation of sediment transport as an erodible sediment pool is depleted: San Francisco Bay, 1999

    USGS Publications Warehouse

    Schoellhamer, David H.

    2011-01-01

    The quantity of suspended sediment in an estuary is regulated either by transport, where energy or time needed to suspend sediment is limiting, or by supply, where the quantity of erodible sediment is limiting. This paper presents a hypothesis that suspended-sediment concentration (SSC) in estuaries can suddenly decrease when the threshold from transport to supply regulation is crossed as an erodible sediment pool is depleted. This study was motivated by a statistically significant 36% step decrease in SSC in San Francisco Bay from water years 1991–1998 to 1999–2007. A quantitative conceptual model of an estuary with an erodible sediment pool and transport or supply regulation of sediment transport is developed. Model results confirm that, if the regulation threshold was crossed in 1999, SSC would decrease rapidly after water year 1999 as observed. Estuaries with a similar history of a depositional sediment pulse followed by erosion may experience sudden clearing.

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

    USGS Publications Warehouse

    Carr, Robert Scott; Chapman, Duane C.

    1992-01-01

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

  20. Preliminary results of experiments to determine the effects of suspended sediments on the estuarine copepod Eurytemora affinis

    NASA Astrophysics Data System (ADS)

    Sellner, K. G.; Bundy, M. H.

    1987-11-01

    Suspended sediment did not significantly affect Eurytemora affinis, which is the numerically dominant, late winter, early spring mesozooplankton taxon in Chesapeake Bay. In preliminary analyses of survival, broods per female and nauplii development for suspended sediment concentrations from 0 to 350 mg l -1, few significant differences were observed between populations exposed to no suspended sediment, and those in 50, 100 and 350 mg l -1. However, in every case, highest suspended sediment levels reduced physiological or reproductive parameters in the copepod. These results suggest that current levels of suspended sediment in the Chesapeake Bay should not reduce population success of the copepod. However, copepod production could decline at slightly higher suspended sediment concentrations resulting from urban population growth and development in the watershed, as well as at levels which are typical of several European estuaries.

  1. Pond sediment magnetite grains show a distinctive microbial community.

    PubMed

    Song, H-K; Sonkaria, S; Khare, V; Dong, K; Lee, H-T; Ahn, S-H; Kim, H-K; Kang, H-J; Lee, S-H; Jung, S P; Adams, J M

    2015-07-01

    Formation of magnetite in anaerobic sediments is thought to be enhanced by the activities of iron-reducing bacteria. Geobacter has been implicated as playing a major role, as in culture its cells are often associated with extracellular magnetite grains. We studied the bacterial community associated with magnetite grains in sediment of a freshwater pond in South Korea. Magnetite was isolated from the sediment using a magnet. The magnetite-depleted fraction of sediment was also taken for comparison. DNA was extracted from each set of samples, followed by PCR for 16S bacterial ribosomal RNA (rRNA) gene and HiSeq sequencing. The bacterial communities of the magnetite-enriched and magnetite-depleted fractions were significantly different. The enrichment of three abundant operational taxonomic units (OTUs) suggests that they may either be dependent upon the magnetite grain environment or may be playing a role in magnetite formation. The most abundant OTU in magnetite-enriched fractions was Geobacter, bolstering the case that this genus is important in magnetite formation in natural systems. Other major OTUs strongly associated with the magnetite-enriched fraction, rather than the magnetite-depleted fraction, include a Sulfuricella and a novel member of the Betaproteobacteria. The existence of distinct bacterial communities associated with particular mineral grain types may also be an example of niche separation and coexistence in sediments and soils, which cannot usually be detected due to difficulties in separating and concentrating minerals.

  2. Iron cycling microbial communities in sediments of the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Reyes, Carolina; Delwig, Olaf; Noriega-Ortega, Beatriz; Dähnke, Kirstin; Böttcher, Michael E.; Friedrich, Michael W.

    2014-05-01

    The biogeochemical cycling of iron is a key early diagenetic process. However, limited information exists about the diversity and metabolic pathways of microorganisms linked to iron cycling in marine sediments. The goal of this study was to determine the bacterial community diversity in sediments showing ongoing dissimilatory iron reduction using 454-pyrosequencing as a first step in characterizing microorganisms potentially involved in iron reduction. For this purpose, two 35 cm cores were sampled from ferruginous sediments in the Skagerrak (SK) and the Bothnian Bay (BB) from the North-Sea Baltic Sea and the northern Baltic Sea respectively. Pore water profiles showed Fe2+ and Mn2+ levels of ~140-150 µM throughout the core below a 6 cm thick oxidized surface layer in SK sediments and ~300 µM below a 2 cm thick surface layer in BB sediments. Dissolved sulphide levels were below detection in both sediments. No significant depletion of SO42- occurred at both sites, further supported by stable S and O isotope analyses of dissolved sulfate at SK site. Only very minor net sulfate reduction is suggested here from the trend in sulphur isotope signatures, in agreement with previously reported gross microbial sulphate rate measurements (Canfield et al., 1993;GCA). Based on these biogeochemical constraints, Fe reduction in the studied sediments is therefore dominated by microbial dissimilatory iron reduction, while cryptic Fe-S-cycling can be largely excluded. 16S rRNA gene sequences indicate Proteobacteria as the dominating microbial group in these sediments. Potential iron and manganese reducing bacteria included Geobacteraceae, Pelobacteraceae, Shewanellaceae, and Oceanospirillales. Additionally, Actinobacteria and Bacteroidetes were present. Also, Fe-oxidizers were present and their occurrence correlated in depth with a Fe-oxide-rich layer, most likely a former buried Fe-oxidation front. Gene sequences point to the presence of Mariprofundus in SK sediments and

  3. The archaebacterial communities in Antarctic bathypelagic sediments

    NASA Astrophysics Data System (ADS)

    Gillan, David C.; Danis, Bruno

    2007-08-01

    16S ribosomal DNA clone library analysis was performed to assess archaeal diversity within three surficial sediment samples obtained from the bathypelagic zone (depth: 2165-3406 m) of the Weddell Sea, Antarctica. The nearly complete 16S rDNA gene (1440 bp) was obtained for 146 clones and 46 phylotypes were defined. The majority of the sequences (>99%) formed three clusters within the Marine Group I Crenarchaeota. The most important cluster, with 78.8% of the clones, included Candidatus Nitrosopumilus maritimus, a mesophilic archaeon able to oxidize ammonia. The most important subgroup in that cluster was the APA4-0cm subgroup (with 62.3% of the clones). This subgroup might represent important Crenarchaeota in the functioning of the bathypelagic sedimentary ecosystems of the Weddell Sea because it dominated the clone libraries in all sampling stations, and was found in sediments separated by very large geographic distances. Only one clone grouped within the Euryarchaeota. This euryarchaeal clone could not be affiliated with any of the previously defined clusters and might represent a novel euryarchaeal lineage.

  4. Comparison of sediment grain size characteristics on nourished and un-nourished estuarine beaches and impacts on horseshoe crab habitat, Delaware Bay, New Jersey

    USGS Publications Warehouse

    Jackson, N.L.; Smith, D.R.; Nordstrom, K.F.

    2005-01-01

    This study was undertaken to determine whether nourished and un-nourished estuarine beaches have conspicuous differences in sediment size and sorting that could affect their value as habitat for horseshoe crabs. Comparisons are made of beach profiles and sediment samples gathered at 0.15 m and 0.30 m depths on the backshore, at spring tide elevation, neap tide elevation, and the lower foreshore on 5 un-nourished and 3 nourished beaches in Delaware Bay, where tidal range is <2.0 m. The backshore is at least 0.5 m higher on the recently nourished beaches than on a nearby un-nourished beach reworked by storm waves. Nourishing these beaches to elevations higher than natural overwash heights will restrict natural evolution of the upper beach. Sediments at spring tide elevation on un-nourished sites average 0.72 mm in diameter at 0.15 m depth and 0.67 mm at 0.30 m depth.The similarity in size implies a relatively deep active layer in the zone of maximum cut and fill associated with cyclic profile change during low frequency, high magnitude storms. Sedimentary changes at neap tide elevation may be influenced more by depth of activation by waves than by cycles of deposition and erosion. Sediment at 0.15 m depth at spring and neap locations on the foreshore of nourished beaches is finer (0.51 mm) and better sorted (0.82 phi) than at 0.30 m depth (0.91 mm, 1.38 phi), implying that waves have not reworked the deeper sediments. Differences in sediment characteristics at depth may persist on eroding nourished beaches, where unreworked fill is close to the surface. Sediment texture influences horseshoe crab egg viability and development. Lower rates of water movement through the foreshore and greater thickness of the capillary fringe on nourished sites suggests that greater moisture retention will occur where horseshoe crabs bury eggs and may provide more favorable conditions for egg development, but the depth of these conditions will not be great on a recently nourished beach

  5. Ban on commercial fishing in the estuarine waters of New South Wales, Australia: Community consultation and social impacts

    SciTech Connect

    Momtaz, Salim Gladstone, William

    2008-02-15

    In its effort to resolve the conflict between commercial and recreational fishers the New South Wales (NSW) government (NSW Fisheries) banned commercial fishing in the estuarine waters. The NSW Fisheries conducted a number of studies and held meetings with the affected communities including commercial fishers prior to the implementation of the ban. To investigate how community consultation played a role in the decision-making process especially as perceived by the commercial fishers and to determine actual social impacts of the ban on commercial fishers, in-depth interviews were conducted with the commercial fishers. This research reveals that despite the NSW Fisheries' consultations with commercial fishers prior to the closure, the latter were confused about various vital aspects of the decision. It further reveals that, the commercial fishers faced a number of significant changes as a result of this decision. We argue that a better decision-making process and outcome would have been possible through a meaningful consultation with the commercial fishers and a social impact assessment.

  6. Denitrification, Dissimilatory Reduction of Nitrate to Ammonium, and Nitrification in a Bioturbated Estuarine Sediment as Measured with 15N and Microsensor Techniques

    PubMed Central

    Binnerup, Svend Jørgen; Jensen, Kim; Revsbech, Niels Peter; Jensen, Mikael Hjorth; Sørensen, Jan

    1992-01-01

    Nitrogen and oxygen transformations were studied in a bioturbated (reworked by animals) estuarine sediment (Norsminde Fjord, Denmark) by using a combination of 15N isotope (NO3-), specific inhibitor (C2H2), and microsensor (N2O and O2) techniques in a continuous-flow core system. The estuarine water was NO3- rich (125 to 600 μM), and NO3- was consistently taken up by the sediment on the four occasions studied. Total NO3- uptake (3.6 to 34.0 mmol of N m-2 day-1) corresponded closely to N2 production (denitrification) during the experimental steady state, which indicated that dissimilatory, as well as assimilatory, NO3- reduction to NH4+ was insignificant. When C2H2 was applied in the flow system, denitrification measured as N2O production was often less (58 to 100%) than the NO3- uptake because of incomplete inhibition of N2O reduction. The NO3- formed by nitrification and not immediately denitrified but released to the overlying water, uncoupled nitrification, was calculated both from 15NO3- dilution and from changes in NO3- uptake before and after C2H2 addition. These two approaches gave similar results, with rates ranging between 0 and 8.1 mmol of N m-2 day-1 on the four occasions. Attempts to measure total nitrification activity by the difference between NH4+ fluxes before and after C2H2 addition failed because of non-steady-state NH4+ fluxes. The vertical distribution of denitrification and oxygen consumption was studied by use of N2O and O2 microelectrodes. The N2O profiles measured during the experimental steady state were often irregularly shaped, and the buildup of N2O after C2H2 was added was much too fast to be described by a simple diffusion model. Only bioturbation by a dense population of infauna could explain these observations. This was corroborated by the relationship between diffusive and total fluxes, which showed that only 19 to 36 and 29 to 62% of the total O2 uptake and denitrification, respectively, were due to diffusion-reaction processes at

  7. Patterns of Distribution of Macro-fauna in Different Types of Estuarine, Soft Sediment Habitats Adjacent to Urban and Non-urban Areas

    NASA Astrophysics Data System (ADS)

    Lindegarth, M.; Hoskin, M.

    2001-02-01

    Urban development typically creates a large number of potentially interacting disturbances that may cause impacts on assemblages of animals and plans in estuarine habitats. We tested predictions from the general model that intertidal areas exposed to different types of disturbances have different types of assemblages of benthic macrofauna. Different parts of the Port Hacking Estuary (New South Wales, Australia) are exposed to varying degrees of disturbance by human activities. We predicted that the average structure of assemblages of intertidal animals, and patterns of variability would differ between urban and non-urban areas of Port Hacking. Consistent with previous observations from the literature, there were differences in average structure between urban and non-urban sandy areas. Qualitative differences between abundances of individual taxa in urban and non-urban areas were generally not consistent with previous observations. Differences between assemblages in urban and non-urban areas were not observed in muddy sediments, nor in sediments among mangroves and seagrass. No significant differences in variability was observed between urban and non-urban areas. Two general models may be proposed to explain the observed differences in response t