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Sample records for freshwater sediment downstream

  1. Impacts of Three Gorges Reservoir on the sedimentation regimes in the downstream-linked two largest Chinese freshwater lakes

    PubMed Central

    Zhou, Yongqiang; Jeppesen, Erik; Li, Jingbao; Zhang, Yunlin; Zhang, Xinping; Li, Xichun

    2016-01-01

    We studied the impacts of Three Gorges Reservoir (TGR) on the sedimentation regimes in the downstream-linked two largest Chinese freshwater lakes, Lake Dongting and Lake Poyang. Our results indicate that up to 1.73 × 109 t sediment was retained in TGR from June 2003 to December 2014. This resulted in a 145.9 × 106 t yr−1 decline in the suspended sediment load at Zhicheng and a 16.8 × 106 t yr−1 lower sediment flow from Yangtze River to Lake Dongting, which partially explains the 13.4 × 106 t yr−1 lower sedimentation in Lake Dongting during the post-TGR period. Furthermore, TGR resulted in a 0.5 ± 0.3 m reduction of the multi-year mean water level at the Lake Poyang outlet Hukou, accelerating the suspended sediment export discharge from the lake. The reduced sedimentation in Lake Poyang during the post-TGR period was estimated to 6.3 × 106 t yr−1. We estimate that a monthly mean concentration of sediment flow from TGR below 0.60 kg m−3 will lead to erosion in Lake Dongting and Lake Poyang. Better regulation of TGR may extend the life expectancy of the two vanishing large lakes. PMID:27748435

  2. Measurement of oxytetracycline and emamectin benzoate in freshwater sediments downstream of land based aquaculture facilities in the Atlantic Region of Canada.

    PubMed

    Lalonde, Benoit A; Ernst, William; Greenwood, Lyndsay

    2012-09-01

    This study investigated the occurrence of oxytetracycline (OTC) and emamectin benzoate (EB) in sediments located near the effluent outfall from four freshwater aquaculture facilities in Atlantic Canada. While two facilities had no detectable concentrations of EB or OTC, two facilities had detectable concentrations of one or both of these chemicals. Concentrations ranged from <0.05-18 mg/kg to <0.01-2.5 mg/kg for OTC and EB respectively. Although these values could not be compared with freshwater toxicant values, some of the concentrations of EB and OTC detected were higher than LC(50) values calculated for marine invertebrates. OTC concentrations measured in this study are also of a magnitude which has been known to produce resistant bacteria.

  3. Cable Bacteria in Freshwater Sediments

    PubMed Central

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

    2015-01-01

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

  4. Cable Bacteria in Freshwater Sediments.

    PubMed

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

    2015-09-01

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

  5. Sulfur cycling in freshwater sediments

    NASA Technical Reports Server (NTRS)

    Klug, M. J.

    1985-01-01

    Organic sulfur containing compounds represent greater than 80% of the total sulfur in sediments of eutrophic freshwater lakes. Although sedimentary sulfur is predominantly in the form of organic compounds, more sulfur is transformed by sulfate reduction than by any other process. Rates of sulfate reduction in these sediments average 7 mmol/sq m/day. This rate is 19 times greater than the net rate of production of inorganic sulfur from organic compounds on an annual basis.

  6. Influence of sediment storage on downstream delivery of contaminated sediment

    USGS Publications Warehouse

    Malmon, D.V.; Reneau, S.L.; Dunne, T.; Katzman, D.; Drakos, P.G.

    2005-01-01

    Sediment storage in alluvial valleys can strongly modulate the downstream migration of sediment and associated contaminants through landscapes. Traditional methods for routing contaminated sediment through valleys focus on in-channel sediment transport but ignore the influence of sediment exchanges with temporary sediment storage reservoirs outside the channel, such as floodplains. In theory, probabilistic analysis of particle trajectories through valleys offers a useful strategy for quantifying the influence of sediment storage on the downstream movement of contaminated sediment. This paper describes a field application and test of this theory, using 137Cs as a sediment tracer over 45 years (1952-1997), downstream of a historical effluent outfall at the Los Alamos National Laboratory (LANL), New Mexico. The theory is parameterized using a sediment budget based on field data and an estimate of the 137Cs release history at the upstream boundary. The uncalibrated model reasonably replicates the approximate magnitude and spatial distribution of channel- and floodplain-stored 137Cs measured in an independent field study. Model runs quantify the role of sediment storage in the long-term migration of a pulse of contaminated sediment, quantify the downstream impact of upstream mitigation, and mathematically decompose the future 137Cs flux near the LANL property boundary to evaluate the relative contributions of various upstream contaminant sources. The fate of many sediment-bound contaminants is determined by the relative timescales of contaminant degradation and particle residence time in different types of sedimentary environments. The theory provides a viable approach for quantifying the long-term movement of contaminated sediment through valleys. Copyright 2005 by the American Geophysical Union.

  7. Downstream Sediment Sorting as a Fractionation Process

    NASA Astrophysics Data System (ADS)

    Paola, C.; Fedele, J. J.

    2007-12-01

    Downstream size segregation in net depositional systems can be thought of as a fractination process in which a well mixed, heterogeneous input is unmixed based on its relative mobility. Although we are accustomed to thinking of the segregation process as hydraulically driven and rather complex, we argue that at large time and length scales size segregation can be substantially simplified. The main controls are the downstream distribution of sediment extraction, which is typically controlled externally (e.g. by subsidence) and the size distribution of the sediment supply. Hydraulics plays a secondary role because of the tendency for river channels to self organize to a shape that maintains a limited range of dimensionless shear stress on the channel bed. The end result of this line of reasoning is a simple method for calculating downstream size segregation in depositional systems that is in good agreement with the limited data available. In terms of local dynamics, we introduce evidence that topographic roughness plays an important role. This is not explicitly incorporated in our analysis, and the best ways to characterize roughness for this purpose are yet to be determined. Finally, to estimate the importance of abrasion effects at large scales, we re-introduce a dimensionless parameter to describe the relative importance of abrasion, which sorts material by durability, and selective transport, which sorts by transportability.

  8. Sediment quality in freshwater impoundments at Savannah National Wildlife Refuge

    USGS Publications Warehouse

    Winger, P.V.; Lasier, P.J.

    2004-01-01

    Freshwater impoundments at Savannah National Wildlife Refuge (NWR), South Carolina, provide an important habitat for wildlife species, but degraded sediment quality in the Savannah River downstream of the discharge from two impoundments have caused concern about potential contaminant problems within the impoundments. The quality of sediments from five impoundments (impoundments no. 1, 2, 6, 7, and 17) on the NWR was evaluated using physical and chemical characterization, contaminant concentrations (metals, organochlorine pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons), and toxicity testing. Survival of Hyalella azteca (freshwater amphipod) exposed for 28 days to solid-phase sediments was not significantly different from controls, but growth was significantly decreased at several sites. Survival in 96-hour exposures to sediment pore water was significantly decreased at most sites. Factors contributing to the toxic responses were low pH (3.7 to 4.1), ammonia (20 mg/L), and increased concentrations of cations in the pore water. The excess of simultaneously extracted metals over the acid volatile sulfides in the sediments was also typical of sites displaying decreased sediment quality. Elemental concentrations in pore water were negatively correlated with pH, and the highest concentrations were observed in impoundment no. 7. The acidic nature of the sediment in this impoundment was exacerbated by recent draining, burning, and disking, which allowed oxidation of the previously anoxic wetland sediment. Sediment disturbance and mixing of vegetation into the sediments by disking may also have contributed to the formation of ammonia caused by microbial decomposition of the fragmented organic matter. Contaminants were not detected in sediments from the impoundments, but releases of acidic water with increased levels of sediment cations from the impoundments may have contributed to the degraded sediment conditions previously observed in the river

  9. Toxicity testing of freshwater sediment collected near freshwater aquaculture facilities in the Maritimes, Canada.

    PubMed

    Lalonde, B A; Garron, C; Ernst, B; Jackman, P

    2013-01-01

    In the Atlantic region of Canada, there are close to 50 land-based freshwater aquaculture facilities, most of which discharge wastewater to freshwater receiving environments. This study was designed to assess the chemical and toxicological characteristics of sediments in those receiving environments. Thirty sediment samples were collected from 3 locations (upstream, outfall and downstream) at seven freshwater aquaculture facilities. Toxicity tests conducted included amphipod growth, amphipod survival and Microtox™. Sediments were also analysed for ammonia/porewater ammonia, redox and sulphide. Porewater ammonia concentration for the amphipod survival test ranged from 0.01 to 42 mg/L at the conclusion of the 14-day survival test. Ammonia concentration in sediment ranged from 0.3-202 μg/g, sulphide concentration ranged from 0.15 to 17.4 μg/g, yet redox ranged from 32 to 594 mV. Microtox™  IC50 values ranged from 108,00 to >164,000 mg/L, yet amphipod survival ranged from 0 to 100%, depending on sampling locations. Amphipod survival was significantly related (P < 0.05) to porewater ammonia (at time = 0 and 14 days) and Microtox™  IC50 was significantly related (P < 0.05) to ammonia, sulphide and redox levels. These results indicate that discharges from some the land-based aquaculture facilities are impacting sediment dwelling benthic invertebrates at the outfall but that impact largely disappears by 100 m downstream. Furthermore those impacts were rarely detected during the early winter season, when biomass production was at the lowest.

  10. A bioaccumulation bioassay for freshwater sediments

    USGS Publications Warehouse

    Mac, Michael J.; Noguchi, George E.; Hesselberg, Robert J.; Edsall, Carol C.; Shoesmith, John A.; Bowker, James D.

    1990-01-01

    A laboratory bioassay is described for determining the bioavailability of contaminants from freshwater sediments. The bioassay consists of 10-d exposures to whole sediments under flow-through conditions. After testing five species, the fathead minnow (Pimephales promelas) and the earthworm (Lubricus terrestris) were recommended for use in the test. When the availability of polychlorinated biphenyls (PCBs), Hg and Zn from Great Lakes sediments was examined in laboratory exposures, only the PCBs were accumulated. A field validation study demonstrated that the magnitude of accumulation in laboratory exposures was similar to that in organisms caged in the field. A protocol is recommended for using the test as a standardized bioaccumulation bioassay.

  11. Downstream cumulative effects of land use on freshwater communities

    NASA Astrophysics Data System (ADS)

    Kuglerová, L.; Kielstra, B. W.; Moore, D.; Richardson, J. S.

    2015-12-01

    Many streams and rivers are subject to disturbance from intense land use such as urbanization and agriculture, and this is especially obvious for small headwaters. Streams are spatially organized into networks where headwaters represent the tributaries and provide water, nutrients, and organic material to the main stems. Therefore perturbations within the headwaters might be cumulatively carried on downstream. Although we know that the disturbance of headwaters in urban and agricultural landscapes poses threats to downstream river reaches, the magnitude and severity of these changes for ecological communities is less known. We studied stream networks along a gradient of disturbance connected to land use intensity, from urbanized watersheds to watersheds placed in agricultural settings in the Greater Toronto Area. Further, we compared the patterns and processes found in the modified watershed to a control watershed, situated in a forested, less impacted landscape. Preliminary results suggest that hydrological modifications (flash floods), habitat loss (drainage and sewer systems), and water quality issues of small streams in urbanized and agricultural watersheds represent major disturbances and threats for aquatic and riparian biota on local as well as larger spatial scales. For example, communities of riparian plants are dominated by species typical of the land use on adjacent uplands as well as the dominant land use on the upstream contributing area, instead of riparian obligates commonly found in forested watersheds. Further, riparian communities in disturbed environments are dominated by invasive species. The changes in riparian communities are vital for various functions of riparian vegetation. Bank erosion control is suppressed, leading to severe channel transformations and sediment loadings in urbanized watersheds. Food sources for instream biota and thermal regimes are also changed, which further triggers alterations of in-stream biological communities

  12. Control of sediment deposition rates in two mid-Atlantic Coast tidal freshwater wetlands

    NASA Astrophysics Data System (ADS)

    Darke, A. K.; Megonigal, J. P.

    2003-05-01

    Eustatic sea level rise and rapidly increasing coastal development threaten tidal freshwater wetlands. Sediment deposition is one process that affects their ability to maintain surface elevations relative to adjacent rivers. Sediment dynamics in salt marshes have been studied extensively, but little is known about the factors that control sediment deposition rates in tidal freshwater wetlands. We examined geomorphic, hydrological, and biotic factors that may influence sedimentation in two tidal freshwater wetlands that fell at opposite ends of the riverine-estuarine continuum. Our data demonstrate that sediment dynamics are highly variable among tidal freshwater wetlands, and are influenced by the location of the wetland on the continuum. Sediment deposition was up to 10 times higher during the growing season at the downstream site than the upstream site. Plant density and height were highly correlated with sediment deposition rates at the downstream site ( r≥0.92, p≤0.009) but not at the upstream site. Elevation, flood depth, and flood duration were correlated with deposition rates only when each site/season combination was considered separately. River suspended sediment and surficial floodwater suspended sediment concentrations were significantly higher at the downstream site ( p=0.02 and p=0.04, respectively). These data suggest that vegetation is important in determining sediment deposition rates when river suspended sediment is not limiting, which is not always the case. Longer flood duration increased sediment deposition, but was of secondary importance. Land use and proximity to the turbidity maximum (near the forward extent of the salt water intrusion) appear to be critically important in determining river suspended sediment availability in the tidal freshwater zone of the Mattaponi River, VA.

  13. Measurement of sediment settling velocities in a tidal freshwater wetland

    NASA Astrophysics Data System (ADS)

    van der Deijl, Eveline C.; van der Perk, Marcel; Visser, Renske; Verschelling, Eelco; Middelkoop, Hans

    2015-04-01

    This study aims to determine the settling characteristics of suspended sediment in the Kleine Noordwaard tidal freshwater wetland in the south-western part of the Netherlands. This wetland consists of a recently inundated former polder area in the Biesbosch area, in which water and sediment have been reintroduced since 2009. The area mainly receives sediment from the Nieuwe Merwede River, a downstream distributary of the Rhine River. In July, September, and October 2014, water samples were collected in 30 cm diameter PVC settling tubes near the inlet and outlet of the area. The settling tubes were transported horizontally to a field laboratory, where the settling velocity measurements started by placing the settling tube in upright position within 1 hour after sampling. At logarithmic time increments, 250 ml samples were extracted from the settling tubes through a valve at a depth of 250 mm below the top of the tube. The sediment concentrations in the samples were determined by filtering through 0.45 μm pore size membrane filters. First results show that the suspended sediment concentrations were low and varied between 10 mg l-1 and 35 mg l-1. In general, the sediment concentrations decreased exponentially during the measurements with exponents ranging between 0.98 × 10-4s-1 and 1.27 × 10-4s-1. The median settling velocities were rather consistent between the measurement locations and measurement periods with median settling velocities of about 0.04 mm s-1 and 75th percentiles between 0.07 mm s-1 and 0.11 mm s-1.

  14. Sediment accretion in tidal freshwater forests and oligohaline marshes of the Waccamaw and Savannah Rivers, USA

    USGS Publications Warehouse

    Ensign, Scott H.; Hupp, Cliff R.; Noe, Gregory B.; Krauss, Ken W.; Stagg, Camille L.

    2014-01-01

    Sediment accretion was measured at four sites in varying stages of forest-to-marsh succession along a fresh-to-oligohaline gradient on the Waccamaw River and its tributary Turkey Creek (Coastal Plain watersheds, South Carolina) and the Savannah River (Piedmont watershed, South Carolina and Georgia). Sites included tidal freshwater forests, moderately salt-impacted forests at the freshwater–oligohaline transition, highly salt-impacted forests, and oligohaline marshes. Sediment accretion was measured by use of feldspar marker pads for 2.5 year; accessory information on wetland inundation, canopy litterfall, herbaceous production, and soil characteristics were also collected. Sediment accretion ranged from 4.5 mm year−1 at moderately salt-impacted forest on the Savannah River to 19.1 mm year−1 at its relict, highly salt-impacted forest downstream. Oligohaline marsh sediment accretion was 1.5–2.5 times greater than in tidal freshwater forests. Overall, there was no significant difference in accretion rate between rivers with contrasting sediment loads. Accretion was significantly higher in hollows than on hummocks in tidal freshwater forests. Organic sediment accretion was similar to autochthonous litter production at all sites, but inorganic sediment constituted the majority of accretion at both marshes and the Savannah River highly salt-impacted forest. A strong correlation between inorganic sediment accumulation and autochthonous litter production indicated a positive feedback between herbaceous plant production and allochthonous sediment deposition. The similarity in rates of sediment accretion and sea level rise in tidal freshwater forests indicates that these habitats may become permanently inundated if the rate of sea level rise increases.

  15. Sediment, land use, and freshwater mussels: Prospects and problems

    USGS Publications Warehouse

    Brim-Box, J.; Mossa, J.

    1999-01-01

    The decline in freshwater mussel populations in many river basins throughout North America has been attributed, in part, to land-use modifications that cause changes in sediment regimes. However, the specific associations that mussels have with stream sediments are poorly understood, making it difficult to assess the impacts of changes in sedimentation rates on unionid mussels. Both bed and suspended materials, and concomitant changes in channel form associated with changes in sediment supply, may affect mussels in numerous ways at various stages in their life cycle. Considerable debate and uncertainty remains regarding the strength of associations between sediments and mussels, including whether increased sedimentation is a cause of recent mussel declines. It is important to be aware of appropriate procedures for sampling and analyzing fluvial sediments, and the nature of sediment sources, to adequately assess relationships between unionid mussels and fluvial sediments.

  16. Quantitative centrifugation to extract benthic protozoa from freshwater sediments.

    PubMed

    Starink, M; Bär-Gilissen, M J; Bak, R P; Cappenberg, T E

    1994-01-01

    TWO METHODS FOR EXTRACTING PROTISTS FROM FRESHWATER SEDIMENT ARE DESCRIBED: (i) an adapted isopycnic centrifugation technique for sandy and gyttja-like sediments and (ii) a rate zonal centrifugation technique for sediments rich in particulate organic material (litter-like sediments). The recoveries of protists during isopycnic centrifugation in media of several densities were compared. No significant losses in sodium diatrizoate and Percoll were recorded. After known amounts of nanoflagellates were added to azoic sediments, the protists were extracted and counted. For sandy sediments, we found 100% recovery, and for the gyttja-like sediments we found a maximum recovery of 94%. The recovery of protozoa extracted from litter-like sediments, characteristic of littoral systems, depends on a given centrifugal force, on time, and on the dimensions of the flagellates. A recovery model which takes into account cell dimensions and centrifugation characteristics gives the minimum expected recovery.

  17. Comparisons of Sediment Test Volumes for Freshwater Solid Phase Sediment Toxicity Tests

    EPA Science Inventory

    Laboratory tests with benthic macroinvertebrates are commonly used to assess the potential toxicity of contaminated sediments, and detailed standard test procedures have been developed for various species. For freshwater, two benthic organisms, Hyalella azteca and Chironomus dil...

  18. Formation of Dimethyl Sulfide and Methanethiol in Anoxic Freshwater Sediments

    PubMed Central

    Lomans, B. P.; Smolders, A.; Intven, L. M.; Pol, A.; Op, De; Van Der Drift, C.

    1997-01-01

    Concentrations of volatile organic sulfur compounds (VOSC) were measured in water and sediment columns of ditches in a minerotrophic peatland in The Netherlands. VOSC, with methanethiol (4 to 40 nM) as the major compound, appeared to be mainly of sediment origin. Both VOSC and hydrogen sulfide concentrations decreased dramatically towards the water surface. High methanethiol and high dimethyl sulfide concentrations in the sediment and just above the sediment surface coincided with high concentrations of hydrogen sulfide (correlation factors, r = 0.91 and r = 0.81, respectively). Production and degradation of VOSC were studied in 32 sediment slurries collected from various freshwater systems in The Netherlands. Maximal endogenous methanethiol production rates of the sediments tested (up to 1.44 (mu)mol per liter of sediment slurry (middot) day(sup-1)) were determined after inhibition of methanogenic and sulfate-reducing populations in order to stop VOSC degradation. These experiments showed that the production and degradation of VOSC in sediments are well balanced. Statistical analysis revealed multiple relationships of methanethiol production rates with the combination of methane production rates (indicative of total anaerobic mineralization) and hydrogen sulfide concentrations (r = 0.90) or with the combination of methane production rates and the sulfate/iron ratios in the sediment (r = 0.82). These findings and the observed stimulation of methanethiol formation in sediment slurry incubations in which the hydrogen sulfide concentrations were artificially increased provided strong evidence that the anaerobic methylation of hydrogen sulfide is the main mechanism for VOSC formation in most freshwater systems. Methoxylated aromatic compounds are likely a major source of methyl groups for this methylation of hydrogen sulfide, since they are important degradation products of the abundant biopolymer lignin. Increased sulfate concentrations in several freshwater

  19. Bioavailability of fluoranthene in freshwater sediment toxicity tests

    SciTech Connect

    Suedel, B.C.; Rodgers, J.H. Jr. ); Clifford, P.A. )

    1993-01-01

    To examine equilibrium-partitioning model predictions of interstitial water concentrations of fluoranthene as part of the equilibrium-partitioning (EqP) approach to sediment quality criteria development, the bioavailability (toxicity) of fluoranthene-amended sediment to Hyalella azteca, Daphnia magna, and Chironomus tentans was determined. Fluoranthene was added to three freshwater sediments with similar organic carbon content. Predicted interstitial water concentrations from the equilibrium-partitioning model were similar to measured interstitial water concentrations for WRFS and TR sediment, but the model underpredicted measured values for LF sediment by a factor of two. EC50s for Daphnia magna, Hyalella azteca, and Chironomus tentans in interstitial water were a factor of two to five greater for LF than for WRFS and TR sediments. Factors other than organic carbon content of sediments probably contributed to the variability in bioavailability of fluoranthene. Based on 10-d sediment toxicity tests with Hylella azteca, Daphnia magna, and Chironomus tentans, organic carbon-normalized sediment concentrations were better predictors of toxicity than interstitial water and bulk sediment fluoranthene concentrations. In 10-d aqueous-phase tests with fluoranthene, Chironomus tentans and Hyalella azteca were twice as sensitive as Daphnia magna.

  20. Remobilisation of uranium from contaminated freshwater sediments by bioturbation

    NASA Astrophysics Data System (ADS)

    Lagauzère, S.; Motelica-Heino, M.; Viollier, E.; Stora, G.; Bonzom, J. M.

    2014-06-01

    Benthic macro-invertebrate bioturbation can influence the remobilisation of uranium (U) initially associated with freshwater sediments, resulting in a high release of this pollutant through the overlying water column. Given the potential negative effects on aquatic biocenosis and the global ecological risk, it appears crucial to improve our current knowledge concerning the biogeochemical behaviour of U in sediments. The present study aimed to assess the biogeochemical modifications induced by Tubifex tubifex (Annelida, Clitellata, Tubificidae) bioturbation within the sediment in order to explain such a release of U. To reach this goal, U distribution between solid and solute phases of a reconstructed benthic system (i.e. in mesocosms) inhabited or not by T. tubifex worms was assessed in a 12-day laboratory experiment. Thanks notably to fine-resolution (mm-scale) measurements (e.g. "diffusive equilibrium in thin-films" DET gel probes for porewater, bioaccumulation in worms) of U and main chemical species (iron, sulfate, nitrate and nitrite), this work (i) confirmed that the removal of bottom sediment particles to the surface through the digestive tract of worms greatly favoured oxidative loss of U in the water column, and (ii) demonstrated that both U contamination and bioturbation of T. tubifex substantially influenced major microbial-driven biogeochemical reactions in sediments (e.g. stimulation of denitrification, sulfate reduction and iron dissolutive reduction). This study provides the first demonstration of biogeochemical modifications induced by bioturbation in freshwater U-contaminated sediments.

  1. Remobilisation of uranium from contaminated freshwater sediments by bioturbation

    NASA Astrophysics Data System (ADS)

    Lagauzère, S.; Motelica-Heino, M.; Viollier, E.; Stora, G.; Bonzom, J. M.

    2013-10-01

    Previous studies have demonstrated that benthic macro-invertebrate bioturbation can influence the remobilization of uranium initially associated with freshwater sediments resulting in a high release of this pollutant through the overlying water column. Giving the potential negative effects on aquatic biocenosis and the global ecological risk, it appeared crucial to improve our current knowledge concerning the uranium biogeochemical behaviour in sediments. The present study aimed to assess the biogeochemical modifications induced by Tubifex tubifex (Annelida, Clitellata, Tubificidae) bioturbation within the sediment permitting to explain such a release of uranium. To reach this goal, uranium distribution between solid and solute phases of a reconstructed benthic system (i.e. in mesocosms) inhabited or not by T. tubifex worms was assessed in a 12 day laboratory experiment. Thanks notably to fine resolution (mm-scale) measurements (e.g. DET gels probes for porewater, bioaccumulation in worms) of uranium and main chemical species (iron, sulfate, nitrate, nitrite), this work permitted (i) to confirm that the removal of bottom sediment particles to the surface through the digestive tract of worms greatly favours the oxidative loss of uranium in the water column, and (ii) to demonstrate that both uranium contamination and bioturbation of T. tubifex substantially influence major microbial-driven biogeochemical reactions in sediments (e.g. stimulation of denitrification, sulfate-reduction and iron dissolutive reduction). This study provides the first demonstration of biogeochemical modifications induced by bioturbation in freshwater uranium-contaminated sediments.

  2. Silver toxicity to Chironomus tentans in two freshwater sediments

    SciTech Connect

    Call, D.J.; Polkinghorne, C.N.; Markee, T.P.; Brooke, L.T.; Geiger, D.L.; Gorsuch, J.W.; Robillard, K.A.

    1999-01-01

    Sediment collected from two freshwater lakes, West Bearskin Lake (Cook, MN, USA) and Bond Lake (Douglas, WI, USA), was characterized for grain size, total organic carbon, (TOC), acid-volatile sulfides (AVS), simultaneously extracted metals (SEM), and iron (Fe). Both sediments had low levels of TOC. West Bearskin Lake sediment contained more small particles than Bond Lake, which was 95% sand. West Bearskin Lake also had higher SEM and had an Fe content that was approximately 30-fold greater than that of Bond Lake. These sediments were amended with AgNO{sub 3} in a series of concentrations, some of which were intended to exceed the total silver (Ag)-binding capacity of the sediments, allowing for the appearance of dissolved Ag in pore water (PW). Sediment toxicity tests were then designed such that the AgNO{sub 3} amendment levels would result in PW concentrations that bracketed the 10-d concentration causing 50% lethality for dissolved Ag of 0.057 mg/L, as determined in a toxicity test in water alone. The 10-d LC50 values for Chironomus tentans, based upon nominal additions of Ag to the sediments, were 2.75 and 1.17 g Ag per kilogram dry sediment for West Bearskin and Bond Lake sediments, respectively. An LC50 value based upon dissolved Ag in the PW was determined only for Bond Lake sediment and was approximately 275 times greater than the water-only LC50 value. This indicated that a high proportion of the dissolved fraction was not readily bioavailable to cause lethality. A reduction in PW pH and the displacement of other metals from sediment into PW with Ag additions to the sediment likely contributed to the observed mortalities and weight losses, particularly at the higher exposure levels. The concentrations of Ag in these sediments that resulted in biological effects are considerably higher than levels reported in the environment.

  3. Nitrate-dependent anaerobic methane oxidation in a freshwater sediment

    NASA Astrophysics Data System (ADS)

    Norði, Katrin á.; Thamdrup, Bo

    2014-05-01

    Anaerobic oxidation of methane coupled to denitrification (DAOM) is a novel process of potential importance to the regulation of methane emissions from freshwater environments. We established nitrate-enriched microcosms of sediment from a freshwater pond in order to quantify the role of this process in a simulated natural redox zonation. The microcosms were allowed to acclimate to nitrate levels of 1-2 mmol L-1 in the overlying water for 16 months leading to a nitrate penetration of 4 cm. The nitrate enrichment significantly stimulated AOM relative to controls, and based on the similar concentrations of sulfate and reactive Fe(III) in the control sediment we conclude that the observed AOM was coupled to denitrification. DAOM occurred at rates that were two orders of magnitude lower than aerobic methane oxidation rates reported in freshwater sediments, and the process appeared to be limited by nitrate or nitrite even at millimolar nitrate concentrations. By contrast, ammonium was efficiently consumed at the base of the nitrate zone, presumably by the anammox process. Although DAOM was stimulated by nitrate enrichment, there were no significant differences between the methane emission from the control and nitrate-enriched microcosms. Our results provide the first experimental evaluation of the kinetics of DAOM in whole sediment cores and indicate that AOM coupled to denitrification can consume a substantial part of the methane flux in nitrate-rich environments. Because it is much less efficient in scavenging methane than its aerobic counterpart, the anaerobic process will, however, mainly be of significance in the regulation of methane emission from oxygen-depleted systems.

  4. Biotransformation of tributyltin to tin in freshwater river-bed sediments contaminated by an organotin release

    USGS Publications Warehouse

    Landmeyer, J.E.; Tanner, T.L.; Watt, B.E.

    2004-01-01

    The largest documented release of organotin compounds to a freshwater river system in the United States occurred in early 2000 in central South Carolina. The release consisted of an unknown volume of various organotin compounds such tetrabutyltin (TTBT), tributyltin (TBT), tetraoctyltin (TTOT), and trioctyl tin (TOT) and resulted in a massive fish kill and the permanent closures of a municipal wastewater treatment plant and a local city's only drinking-water intake. Initial sampling events in 2000 and 2001 indicated that concentrations of the ecologically toxic TTBT and TBT were each greater than 10 000 ??g/kg in surface-water bed sediments in depositional areas, such as lakes and beaver ponds downstream of the release. Bed-sediment samples collected between 2001 and 2003, however, revealed a substantial decrease in bed-sediment organotin concentrations and an increase in concentrations of degradation intermediate compounds. For example, in bed sediments of a representative beaver pond located about 1.6 km downstream of the release, total organotin concentrations [the sum of TTBT, TBT, and the TBT degradation intermediates dibutyltin (DBT) and monobutyltin (MBT)] decreased from 38 670 to 298 ??g/kg. In Crystal Lake, a large lake about 0.4 km downstream from the beaver pond, total organotin concentrations decreased from 28 300 to less than 5 ??g/kg during the same time period. Moreover, bed-sediment inorganic tin concentrations increased from pre-release levels of less than 800 to 32 700 ??g/kg during this time. These field data suggest that the released organotin compounds, such as TBT, are being transformed into inorganic tin by bed-sediment microbial processes. Microcosms were created in the laboratory that contained bed sediment from the two sites and were amended with tributyltin (as tributyltin chloride) under an ambient air headspace and sacrificially analyzed periodically for TBT, the biodegradation intermediates DBT and MBT, and tin. TBT concentrations

  5. 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.

  6. Influence of sediment presence on freshwater mussel thermal tolerance

    USGS Publications Warehouse

    Archambault, Jennifer M.; Cope, W. Gregory; Kwak, Thomas J.

    2014-01-01

    Median lethal temperature (LT50) data from water-only exposures with the early life stages of freshwater mussels suggest that some species may be living near their upper thermal tolerances. However, evaluation of thermal sensitivity has never been conducted in sediment. Mussels live most of their lives burrowed in sediment, so understanding the effect of sediment on thermal sensitivity is a necessary step in evaluating the effectiveness of the water-only standard method, on which the regulatory framework for potential thermal criteria currently is based, as a test of thermal sensitivity. We developed a method for testing thermal sensitivity of juvenile mussels in sediment and used the method to assess thermal tolerance of 4 species across a range of temperatures common during summer. Stream beds may provide a thermal refuge in the wild, but we hypothesized that the presence of sediment alone does not alter thermal sensitivity. We also evaluated the effects of 2 temperature acclimation levels (22 and 27°C) and 2 water levels (watered and dewatered treatments). We then compared results from the sediment tests to those conducted using the water-only standard methods. We also conducted water-only LT tests with mussel larvae (glochidia) for comparison with the juvenile life stage. We found few consistent differences in thermal tolerance between sediment and water-only treatments, between acclimation temperatures, between waterlevel treatments, among species, or between juvenile and glochidial life stages (LT50 range = 33.3-37.2°C; mean = 35.6°C), supporting our hypothesis that the presence of sediment alone does not alter thermal sensitivity. The method we developed has potential for evaluating the role of other stressors (e.g., contaminants) in a more natural and complex environment.

  7. Microbiological reduction of Sb(V) in anoxic freshwater sediments

    USGS Publications Warehouse

    Oremland, Ronald S.; Kulp, Thomas R.; Miller, Laurence G.; Braiotta, Franco; Webb, Samuel M.; Kocar, Benjamin D; Blum, Jodi S.

    2013-01-01

    Microbiological reduction of millimolar concentrations of Sb(V) to Sb(III) was observed in anoxic sediments from two freshwater settings: (1) a Sb- and As-contaminated mine site (Stibnite Mine) in central Idaho and 2) an uncontaminated suburban lake (Searsville Lake) in the San Francisco Bay Area. Rates of Sb(V) reduction in anoxic sediment microcosms and enrichment cultures were enhanced by amendment with lactate or acetate as electron donors but not by H2, and no reduction occurred in sterilized controls. Addition of 2-14C-acetate to Stibnite Mine microcosms resulted in the production of 14CO2 coupled to Sb(V) reduction, suggesting that this process proceeds by a dissimilatory respiratory pathway in those sediments. Antimony(V) reduction in Searsville Lake sediments was not coupled to acetate mineralization and may be associated with Sb-resistance. The microcosms and enrichment cultures also reduced sulfate, and the precipitation of insoluble Sb(III)-sulfide complexes was a major sink for reduced Sb. The reduction of Sb(V) by Stibnite Mine sediments was inhibited by As(V), suggesting that As(V) is a preferred electron acceptor for the indigenous community. These findings indicate a novel pathway for anaerobic microbiological respiration and suggest that communities capable of reducing high concentrations of Sb(V) commonly occur naturally in the environment.

  8. Microbiological reduction of Sb(V) in anoxic freshwater sediments.

    PubMed

    Kulp, Thomas R; Miller, Laurence G; Braiotta, Franco; Webb, Samuel M; Kocar, Benjamin D; Blum, Jodi S; Oremland, Ronald S

    2014-01-01

    Microbiological reduction of millimolar concentrations of Sb(V) to Sb(III) was observed in anoxic sediments from two freshwater settings: (1) a Sb- and As-contaminated mine site (Stibnite Mine) in central Idaho and 2) an uncontaminated suburban lake (Searsville Lake) in the San Francisco Bay Area. Rates of Sb(V) reduction in anoxic sediment microcosms and enrichment cultures were enhanced by amendment with lactate or acetate as electron donors but not by H2, and no reduction occurred in sterilized controls. Addition of 2-(14)C-acetate to Stibnite Mine microcosms resulted in the production of (14)CO2 coupled to Sb(V) reduction, suggesting that this process proceeds by a dissimilatory respiratory pathway in those sediments. Antimony(V) reduction in Searsville Lake sediments was not coupled to acetate mineralization and may be associated with Sb-resistance. The microcosms and enrichment cultures also reduced sulfate, and the precipitation of insoluble Sb(III)-sulfide complexes was a major sink for reduced Sb. The reduction of Sb(V) by Stibnite Mine sediments was inhibited by As(V), suggesting that As(V) is a preferred electron acceptor for the indigenous community. These findings indicate a novel pathway for anaerobic microbiological respiration and suggest that communities capable of reducing high concentrations of Sb(V) commonly occur naturally in the environment.

  9. Sediment conditions in the San Antonio River Basin downstream from San Antonio, Texas, 2000-13

    USGS Publications Warehouse

    Ockerman, Darwin J.; Banta, J. Ryan; Crow, Cassi L.; Opsahl, Stephen P.

    2015-01-01

    Sediment plays an important role in the ecological health of rivers and estuaries and consequently is an important issue for water-resource managers. To better understand sediment characteristics in the San Antonio River Basin, the U.S. Geological Survey, in cooperation with the San Antonio River Authority, completed a two-part study in the San Antonio River Basin downstream from San Antonio, Texas, to (1) collect and analyze sediment data to characterize sediment conditions and (2) develop and calibrate a watershed model to simulate hydrologic conditions and suspended-sediment loads during 2000–12.

  10. Occurrence of triclosan, triclocarban, and its lesser chlorinated congeners in Minnesota freshwater sediments collected near wastewater treatment plants

    USGS Publications Warehouse

    Venkatesan, Arjun K.; Pycke, Benny F.G.; Barber, Larry B.; Lee, Kathy E.; Halden, Rolf U.

    2012-01-01

    The antimicrobial agents triclosan (TCS), triclocarban (TCC) and their associated transformation products are of increasing concern as environmental pollutants due to their potential adverse effects on humans and wildlife, including bioaccumulation and endocrine-disrupting activity. Analysis by tandem mass spectrometry of 24 paired freshwater bed sediment samples (top 10 cm) collected by the U.S. Geological Survey near 12 wastewater treatment plants (WWTPs) in Minnesota revealed TCS and TCC concentrations of up to 85 and 822 ng/g dry weight (dw), respectively. Concentrations of TCS and TCC in bed sediments collected downstream of WWTPs were significantly greater than upstream concentrations in 58% and 42% of the sites, respectively. Dichloro- and non-chlorinated carbanilides (DCC and NCC) were detected in sediments collected at all sites at concentrations of up to 160 and 1.1 ng/g dw, respectively. Overall, antimicrobial concentrations were significantly higher in lakes than in rivers and creeks, with relative abundances decreasing from TCC > TCS > DCC > NCC. This is the first statewide report on the occurrence of TCS, TCC and TCC transformation products in freshwater sediments. Moreover, the results suggest biological or chemical TCC dechlorination products to be ubiquitous in freshwater environments of Minnesota, but whether this transformation occurs in the WWTP or bed sediment remains to be determined.

  11. Occurrence of triclosan, triclocarban, and Its Lesser Chlorinated Congeners in Minnesota Freshwater Sediments Collected Near Wastewater Treatment Plants

    PubMed Central

    Venkatesan, Arjun K.; Pycke, Benny F.G.; Barber, Larry B.; Lee, Kathy E.; Halden, Rolf U.

    2012-01-01

    The antimicrobial agents triclosan (TCS), triclocarban (TCC) and their associated transformation products are of increasing concern as environmental pollutants due to their potential adverse effects on humans and wildlife, including bioaccumulation and endocrine-disrupting activity. Analysis by tandem mass spectrometry of 24 paired freshwater bed sediment samples (top 10 cm) collected by the U.S. Geological Survey near 12 wastewater treatment plants (WWTPs) in Minnesota revealed TCS and TCC concentrations of up to 85 and 822 ng/g dry weight (dw), respectively. Concentrations of TCS and TCC in bed sediments collected downstream of WWTPs were significantly greater than upstream concentrations in 58% and 42% of the sites, respectively. Dichloro- and non-chlorinated carbanilides (DCC and NCC) were detected in sediments collected at all sites at concentrations of up to 160 and 1.1 ng/g dw, respectively. Overall, antimicrobial concentrations were significantly higher in lakes than in rivers and creeks, with relative abundances decreasing from TCC > TCS > DCC > NCC. This is the first statewide report on the occurrence of TCS, TCC and TCC transformation products in freshwater sediments. Moreover, the results suggest biological or chemical TCC dechlorination products to be ubiquitous in freshwater environments of Minnesota, but whether this transformation occurs in the WWTP or bed sediment remains to be determined. PMID:22742731

  12. HEAVY METAL ACCUMULATION IN SEDIMENT AND FRESHWATER FISH IN U.S. ARCTIC LAKES

    EPA Science Inventory

    Metal concentrations in sediment and two species of freshwater fish (lake trout [Salvelinus namaycush], and grayling [Thymallus arcticus]} were examined in four Arctic lakes in Alaska. Concentrations of several metals were naturally high in the sediment relative to uncontaminated...

  13. Controlled sediment flushing at the Cancano Reservoir (Italian Alps): Management of the operation and downstream environmental impact.

    PubMed

    Espa, Paolo; Brignoli, Maria Laura; Crosa, Giuseppe; Gentili, Gaetano; Quadroni, Silvia

    2016-11-01

    Sediment flushing may be effective to preserve reservoir storage, but concerns arise about sustainability for downstream freshwater ecosystems. We report on the controlled flushing of approximately 110,000 tons of silt from a 120 Mm(3) reservoir on the Adda River, the main tributary of Lake Como, Italy. Technical constraints prevented flushing during high flows, and the operation had to be spread out over three consecutive years (2010-2012) and, for each year, over a rather long time span (40-50 days). To mitigate the downstream impact, the suspended sediment concentration (SSC) of the evacuated water was controlled by regulating the dislodging works inside the reservoir, increasing the streamflow in the regulated tributaries, and operating an instream settling basin. SSC and water flow as well as benthic macroinvertebrates and trout were monitored as far as 28 km below the reservoir. At the most upstream gauging station, SSC peaked up to 100 g/l and ranged from 3.5 to 8 g/l on average per each operation. Stream quality metrics based on macroinvertebrate data evidenced the impairment due to flushing; however, the benthic community showed high resilience, recovering to pre-flushing conditions in 6-9 months. Trout data were biased by stocking and sport fishing and were more difficult to be interpreted. The trout population wouldn't seem remarkably altered, even if a non-negligible impact could be deduced through pre/post-event sample comparison. PMID:27448244

  14. Controlled sediment flushing at the Cancano Reservoir (Italian Alps): Management of the operation and downstream environmental impact.

    PubMed

    Espa, Paolo; Brignoli, Maria Laura; Crosa, Giuseppe; Gentili, Gaetano; Quadroni, Silvia

    2016-11-01

    Sediment flushing may be effective to preserve reservoir storage, but concerns arise about sustainability for downstream freshwater ecosystems. We report on the controlled flushing of approximately 110,000 tons of silt from a 120 Mm(3) reservoir on the Adda River, the main tributary of Lake Como, Italy. Technical constraints prevented flushing during high flows, and the operation had to be spread out over three consecutive years (2010-2012) and, for each year, over a rather long time span (40-50 days). To mitigate the downstream impact, the suspended sediment concentration (SSC) of the evacuated water was controlled by regulating the dislodging works inside the reservoir, increasing the streamflow in the regulated tributaries, and operating an instream settling basin. SSC and water flow as well as benthic macroinvertebrates and trout were monitored as far as 28 km below the reservoir. At the most upstream gauging station, SSC peaked up to 100 g/l and ranged from 3.5 to 8 g/l on average per each operation. Stream quality metrics based on macroinvertebrate data evidenced the impairment due to flushing; however, the benthic community showed high resilience, recovering to pre-flushing conditions in 6-9 months. Trout data were biased by stocking and sport fishing and were more difficult to be interpreted. The trout population wouldn't seem remarkably altered, even if a non-negligible impact could be deduced through pre/post-event sample comparison.

  15. Downstream mixing of sediment and tracers in agricultural catchments: Evidence of changing sediment sources and fluvial processes?

    NASA Astrophysics Data System (ADS)

    Ralph, Timothy; Wethered, Adam; Smith, Hugh; Heijnis, Henk

    2014-05-01

    Land clearance, soil tillage and grazing in agricultural catchments have liberated sediment and altered hydrological connectivity between hillslopes and channels, leading to increased sediment availability, mobilisation and delivery to rivers. The type and amount of sediment supplied to rivers is critical for fluvial geomorphology and aquatic ecosystem health. Contemporary sediment dynamics are routinely investigated using environmental radionuclides such as caesium-137 (Cs-137) and excess lead-210 (Pb-210ex), which can provide information regarding sediment source types and fluvial processes if sediment sources can be distinguished from one another and mixing models applied to representative samples. However, downstream transport, mixing and dilution of radionuclide-labelled sediment (especially from sources with low initial concentrations) can obliterate the tracer signal; sometimes before anything of geomorphological importance happens in the catchment. Can these findings be used as evidence of sediment source variations and fluvial processes when the limits of detection (of Cs-137 in particular) are being exceeded so rapidly downstream? Sediment sources and downstream sediment dynamics were investigated in Coolbaggie Creek, a major supplier of sediment to the Macquarie River in an agricultural catchment with temperate to semi-arid climate in Australia. Radionuclides were used to discriminate between the <63 micron fraction of sediment sources including forested topsoils (Cs-137 11.28 +/- 0.75 Bq/kg; Pb-210ex 181.87 +/- 20.00 Bq/kg), agricultural topsoils (Cs-137 3.21 +/- 0.26 Bq/kg; Pb-210ex 29.59 +/- 10.94 Bq/kg) and sub-soils from channel banks and gullies (Cs-137 1.45 +/- 0.47 Bq/kg; Pb-210ex 4.67 +/- 1.93 Bq/kg). Within the trunk stream, suspended sediment, organic matter and Cs-137 and Pb-210ex concentrations declined downstream. Results from a mixing model suggest that agricultural topsoils account for 95% of fine sediment entering the channel in the

  16. Anaerobic Redox Cycling of Iron by Freshwater Sediment Microorganisms

    SciTech Connect

    Weber, Karrie A.; Urrutia, Matilde M.; Churchill, Perry F.; Kukkadapu, Ravi K.; Roden, Eric E.

    2006-01-01

    The potential for microbially-mediated anaerobic redox cycling of iron (Fe) was examined in a first-generation enrichment culture of freshwater wetland sediment microorganisms. MPN enumerations revealed the presence of significant populations of Fe(III)-reducing (ca. 108 cells mL-1) and Fe(II)-oxidizing, nitrate-reducing organisms (ca. 105 cells mL-1) in the sediment used to inoculate the enrichment cultures. Nitrate reduction commenced immediately following inoculation of acetate-containing (ca. 1 mM) medium with a small quantity (1% vol/vol) of wetland sediment, and resulted in the transient accumulation of NO2- and production of a mixture of end-products including NH4+. Fe(III) oxide (high surface area goethite) reduction took place - after NO3- was depleted and continued until all the acetate was utilized. Addition of NO3 after Fe(III) reduction ceased resulted in the immediate oxidation of Fe(II) coupled to reduction of + NO3-to NH4 . No significant NO2- accumulation was observed during nitrate-dependent Fe(II) oxidation. No Fe(II) oxidation occurred in pasteurized controls. Microbial community structure in the enrichment was monitored by DGGE analysis of PCR amplified 16s rDNA and RT-PCR amplified 16S rRNA, as well as by construction of 16S rDNA clone libraries for four different time points during the experiment. Strong similarities in dominant members of the microbial community were observed in the Fe(III) reduction and nitrate-dependent Fe(II) oxidation phases of the experiment, specifically the common presence of organisms closely related (= 95% sequence similarity) to the genera Geobacter and Dechloromonas. These results indicate that the wetland sediments contained organisms such as Geobacter sp. which are capable of both + dissimilatory Fe(III) reduction and oxidation of Fe(II) with reduction of NO3-reduction to NH4 . Our findings suggest that microbially-catalyzed nitrate-dependent Fe(II) oxidation has the potential to contribute to a dynamic

  17. Sediment Mobilization From Reservoirs Can Cause Short Term Oxygen Depletion In Downstream Receiving Waters

    NASA Astrophysics Data System (ADS)

    Anderson, C.; Schenk, L.; Bragg, H.; Singer, M.; Hume, N.

    2013-12-01

    Reservoir management can cause incidences of short-term sediment mobilization, e.g. during dam removal or drawdown for maintenance or habitat purposes. Much of the associated planning focuses on predicting, quantifying, and mitigating the physical impacts of sediment mobilization, transport, and deposition. Sediment pulses can cause multiple regulatory and management concerns, such as turbidity or suspended sediment concentrations that may exceed State standards, geomorphic change and effects on property or infrastructure, or wildlife impacts such as stress to fish via gill abrasion or burial of critical habitat. Water-quality issues associated with sediment mobilization, including nutrient and contaminant transport, are often given less attention, presumably because their effects are less immediate or because of resource constraints. Recent experience with large pulses of sediment from several western reservoirs involving dam removals and temporary drawdowns indicates that oxygen demand, leading to depletion of downstream dissolved oxygen (DO), can also be a significant short-term concern. During the October 2011 Condit Dam removal on the White Salmon River in Washington, DO in receiving waters about 4.5 km downstream of the dam dropped to less than 1 mg/L within 2 hours of the demolition; in response, salmonids were observed to be in distress, apparently gulping for air at the water surface. DO remained low for at least 24 hours in this reach, and dead fish were observed. In December 2012, during a drawdown designed to aid juvenile-salmonid migration through Fall Creek Reservoir in Oregon, DO dropped precipitously about 1.5 km downstream as turbidity peaked, and a muted DO decrease was also observed approximately 14 miles further downstream despite a large dilution from unaffected sources. Laboratory experiments and modeling using sediments from reservoirs proposed for removal on the Klamath River, California, demonstrated the likelihood for downstream DO

  18. Dam impacts on downstream sediment grain size in a dryland river

    NASA Astrophysics Data System (ADS)

    Dekker, F. J.; Wilcox, A. C.

    2011-12-01

    We examined sediment characteristics on a dammed, sand dominated, dryland river to determine the pattern of grain size adjustment and the extent of sediment deficit resulting from dam-induced changes in water and sediment fluxes. We expected that conditions of sediment deficit would be manifested by coarsening immediately downstream of the dam, but that downstream fining would occur as a function of both tributary inputs and landform heterogeneity, such as canyon and wide floodplain reaches. Grain size data were collected longitudinally downstream on the Bill Williams River (BWR), a major tributary of the Colorado River in Arizona that was dammed in 1968 by Alamo Dam. We took photographs at 30m intervals for digital grain size analysis and collected bulk samples or pebble counts every 300m, for over 20% of the 58km long BWR. We used GIS to delineate the contributing area of approximately 60 ephemeral tributaries entering the BWR mainstem below the dam and to identify canyon and wide floodplain reaches. Whereas upstream of Alamo Dam, bed materials are predominantly sand-sized, in the 4km canyon reach downstream of the dam, the bed material coarsens, with an average size of 72 mm along bars, and >1 m of incision is evident. Bars fine to 33 mm and 23 mm at 8km and 28km downstream of the dam, respectively. Decreasing bar grain size downstream is explained to some extent by an exponential model with a fining coefficient of 0.033km^-1 (r^2=0.50). The grain size variation within gravel samples also decreases downstream. The gravel-dominated reach downstream of the dam lacks tributary inputs of sediments; 75% of the tributary area of the dammed BWR enters the mainstem in the river's lower half. The lower BWR is more sand dominated, which is possibly controlled by a wide, 8km long floodplain reach where surface flow is often discontinuous. Further analysis of sediment dynamics in the BWR using reservoir sedimentation and cosmogenic nuclide data are being used to determine

  19. Enumeration, Isolation, and Characterization of Beggiatoa from Freshwater Sediments

    PubMed Central

    Strohl, William R.; Larkin, John M.

    1978-01-01

    An accurate most-probable-number enumeration method was developed for counting the number of Beggiatoa trichomes from various freshwater sediments. The medium consisted of extracted hay, diluted soil extract, 0.05% acetate, and 15 to 35 U of catalase per ml. The same enrichment medium, but without the acetate, was the best enrichment medium from which to obtain pure cultures because it supported good growth of the beggiatoas without allowing them to be overgrown by other bacteria. A total of 32 strains of Beggiatoa were isolated from seven different freshwater habitats and partially characterized. The strains were separated into five groups based on several preliminary characteristics. Four of the groups contained cells with trichomes of approximately the same diameter (1.5 to 2.7 μm) and may be Beggiatoa leptomitiformis or an unnamed species. The fifth group appeared to be Beggiatoa alba. With the exception of three strains, all of the strains deposited sulfur in the presence of hydrogen sulfide, and all strains grew heterotrophically and deposited poly-β-hydroxybutyrate and volutin when grown on acetate supplemented with low concentrations of other organic nutrients. Thin sections of sulfur-bearing trichomes indicated that the sulfur granules were external to the cytoplasmic membrane and that they were surrounded by an additional membrane. Images PMID:16345330

  20. Preliminary Experimental Results on the Technique of Artificial River Replenishment to Mitigate Sediment Loss Downstream Dams

    NASA Astrophysics Data System (ADS)

    Franca, M. J.; Battisacco, E.; Schleiss, A. J.

    2014-12-01

    The transport of sediments by water throughout the river basins, from the steep slopes of the upstream regions to the sea level, is recognizable important to keep the natural conditions of rivers with a role on their ecology processes. Over the last decades, a reduction on the supply of sand and gravel has been observed downstream dams existing in several alpine rivers. Many studies highlight that the presence of a dam strongly modifies the river behavior in the downstream reach, in terms of morphology and hydrodynamics, with consequences on local ecology. Sediment deficit, bed armoring, river incision and bank instability are the main effects which affect negatively the aquatic habitats and the water quality. One of the proposed techniques to solve the problem of sediment deficit downstream dams, already adopted in few Japanese and German rivers although on an unsatisfactory fashion, is the artificial replenishment of these. Generally, it was verified that the erosion of the replenishments was not satisfactory and the transport rate was not enough to move the sediments to sufficient downstream distances. In order to improve and to provide an engineering answer to make this technique more applicable, a series of laboratory tests are ran as preparatory study to understand the hydrodynamics of the river flow when the replenishment technique is applied. Erodible volumes, with different lengths and submergence conditions, reproducing sediment replenishments volumes, are positioned along a channel bank. Different geometrical combinations of erodible sediment volumes are tested as well on the experimental flume. The first results of the experimental research, concerning erosion time evolution, the influence of discharge and the distance travelled by the eroded sediments, will be presented and discussed.

  1. First-Year Downstream Sediment Budget Following the Marmot Dam Removal from the Sandy River, Oregon

    NASA Astrophysics Data System (ADS)

    Podolak, C. J.; Wilcock, P. R.; Pittman, A.

    2008-12-01

    The October 2007 removal of the Marmot Dam, from the Sandy River, OR, provides an opportunity to assess the impact of increased sediment flux on a river channel. The Sandy River drains the west flank of Mt Hood and typically carries a large load of sand and gravel. The 14-meter-tall dam impounded over 750,000 m3 of sediment, only a small amount of which was removed during the decommissioning. Using a one- dimensional modeling approach, it was assessed that the river could transport the accumulated sediment without large adverse impacts downstream of the dam (Cui et al, 2008 - abstract submitted). In order to observe the actual changes to the river due to the dam removal and to test the modeled predictions, a significant monitoring effort has be in place on the Sandy River including bedload and suspended load measurements, discharge measurements, high-fidelity topographic surveys, repeat photography, multiple airborne LIDAR flights, long profile surveys, as well as mapping and characterizing the grain sizes throughout several reaches downstream of the dam. A key step in the quest to describe and predict the spatial distribution of the sediment throughout the downstream reach is to first account for all the sediment (both stored in the reservoir and supplied from upstream). Here, we examine the transport and deposition downstream of the dam through a 2-fraction sediment budget approach using the former dam as the upstream limit of the reach and choosing a the mouth of a bedrock gorge 7 km below the dam site as the downstream limit. Suspended sediment and bedload measurements taken by the USGS just below the dam site (Major et al, 2008 - abstract submitted) are combined with suspended sediment and bedload measurements collected just below the mouth of the gorge and the annual hydrograph to define the sediment fluxes into and out of the reach. Repeat surveys in the reach below the dam (Wallick et al, 2008 - abstract submitted) provide the measure of change in storage

  2. Effect of zeolite on toxicity of ammonia in freshwater sediments: Implications for toxicity identification evaluation procedures

    SciTech Connect

    Besser, J.M.; Ingersoll, C.G.; Leonard, E.N.; Mount, D.R.

    1998-11-01

    Techniques for reducing ammonia toxicity in freshwater sediments were investigated as part of a project to develop toxicity identification and evaluation (TIE) procedures for whole sediments. Although ammonia is a natural constituent of freshwater sediments, pollution can lead to ammonia concentrations that are toxic to benthic invertebrates, and ammonia can also contribute to the toxicity of sediments that contain more persistent contaminants. The authors investigated the use of amendments of a natural zeolite mineral, clinoptilolite, to reduce concentrations of ammonia in sediment pore water. Zeolites have been widely used for removal of ammonia in water treatment and in aqueous TIE procedures. The addition of granulated zeolite to ammonia-spiked sediments reduced pore-water ammonia concentrations and reduced ammonia toxicity to invertebrates. Amendments of 20% zeolite (v/v) reduced ammonia concentrations in pore water by {ge}70% in spiked sediments with ammonia concentrations typical of contaminated freshwater sediments. Zeolite amendments reduced toxicity of ammonia-spiked sediments to three taxa of benthic invertebrates (Hyalella azteca, Lumbriculus variegatus, and Chironomus tentans), despite their widely differing sensitivity to ammonia toxicity. In contrast, zeolite amendments did not reduce acute toxicity of sediments containing high concentrations of cadmium or copper or reduce concentrations of these metals in pore waters. These studies suggest that zeolite amendments, used in conjunction with toxicity tests with sensitive taxa such as H. azteca, may be an effective technique for selective reduction of ammonia toxicity in freshwater sediments.

  3. Effect of zeolite on toxicity of ammonia in freshwater sediments: Implications for toxicity identification evaluation procedures

    USGS Publications Warehouse

    Besser, J.M.; Ingersoll, C.G.; Leonard, E.N.; Mount, D.R.

    1998-01-01

    Techniques for reducing ammonia toxicity in freshwater sediments were investigated as part of a project to develop toxicity identification and evaluation (TIE) procedures for whole sediments. Although ammonia is a natural constituent of freshwater sediments, pollution can lead to ammonia concentrations that are toxic to benthic invertebrates, and ammonia can also contribute to the toxicity of sediments that contain more persistent contaminants. We investigated the use of amendments of a natural zeolite mineral, clinoptilolite, to reduce concentrations of ammonia in sediment pore water. Zeolites have been widely used for removal of ammonia in water treatment and in aqueous TIE procedures. The addition of granulated zeolite to ammonia-spiked sediments reduced pore-water ammonia concentrations and reduced ammonia toxicity to invertebrates. Amendments of 20% zeolite (v/v) reduced ammonia concentrations in pore water by ???70% in spiked sediments with ammonia concentrations typical of contaminated freshwater sediments. Zeolite amendments reduced toxicity of ammonia-spiked sediments to three taxa of benthic invertebrates (Hyalella azteca, Lumbriculus variegatus, and Chironomus tentans), despite their widely differing sensitivity to ammonia toxicity. In contrast, zeolite amendments did not reduce acute toxicity of sediments containing high concentrations of cadmium or copper or reduce concentrations of these metals in pore waters. These studies suggest that zeolite amendments, used in conjunction with toxicity tests with sensitive taxa such as H. azteca, may be an effective technique for selective reduction of ammonia toxicity in freshwater sediments.

  4. Using stream sediment lithology to explore the roles of abrasion and channel network structure in shaping downstream sediment yields

    NASA Astrophysics Data System (ADS)

    Mueller, E. R.; Smith, M. E.; Pitlick, J.

    2012-12-01

    Both the flux and characteristics of stream sediment evolve downstream in response to variations in sediment supply, abrasion rate, and channel network structure. We use a simple erosion-abrasion mass balance to model the downstream evolution of sediment flux in two adjacent watersheds draining differing mixtures of soft and resistant rock types in the northern Rocky Mountains. Measurements of bed sediment grain size and lithology are used in conjunction with measured bed load and suspended load sediment fluxes to constrain the model. The results show that the downstream evolution in bed load flux and composition can be strongly influenced by subtle differences in underlying geology, which shapes both the abrasion characteristics and travel path lengths of individual rock types. In the Big Wood basin, abrasion rapidly reduces the size of soft sedimentary and volcanic rocks exposed in headwater areas, concentrating resistant granitic rocks in the stream bed and depressing bed load in favor of suspended load. Alternatively, in the North Fork Big Lost basin, volcanic and sedimentary lithologies are exposed throughout the catchment, and the bed material becomes dominated by erodible but resistant quartzitic sandstones. The result is a much higher bed load flux best modeled with modest abrasion rates. In both cases, the best-fit model can reproduce within 5% the composition of the stream bed substrate using realistic erosion and abrasion parameters. The results also demonstrate a strong linkage between modern hillslopes and channel systems even in these formerly glaciated landscapes, as the sediment signature of the primary streams reflects the systematic tapping of distinct source areas. While this work shows promise, measurement of the spatial patterns in the size and composition of bed and suspended load fluxes at locations throughout a channel network would better elucidate that relative importance of supply, sorting, and abrasion processes.

  5. Elevated sulfate reduction in metal-contaminated freshwater lake sediments

    SciTech Connect

    Gough, H.L.; Dahl, A.L.; Tribou, E.; Noble, P.A.; Gaillard, J.-F.; Stahl, D.A.

    2009-01-06

    Although sulfate-reducing prokaryotes have long been studied as agents of metals bioremediation, impacts of long-term metals exposure on biologically mediated sulfur cycling in natural systems remains poorly understood. The effects of long-term exposure to metal stress on the freshwater sulfur cycle were studied, with a focus on biologic sulfate reduction using a combination of microbial and chemical methods. To examine the effects after decades of adaptation time, a field-based experiment was conducted using multiple study sites in a natural system historically impacted by a nearby zinc smelter (Lake DePue, Illinois). Rates were highest at the most metals-contaminated sites (-35 {mu}mol/cm{sup 3}/day) and decreased with decreased pore water zinc and arsenic contamination levels, while other environmental characteristics (i.e., pH, nutrient concentrations and physical properties) showed little between-site variation. Correlations were established using an artificial neural network to evaluate potentially non-linear relationships between sulfate reduction rates (SRR) and measured environmental variables. SRR in Lake DePue were up to 50 times higher than rates previously reported for lake sediments and the chemical speciation of Zn was dominated by the presence of ZnS as shown by X-ray Absorption Spectroscopy (XAS). These results suggest that long-term metal stress of natural systems might alter the biogeochemical cycling of sulfur by contributing to higher rates of sulfate reduction.

  6. Effects of Flaming Gorge Dam hydropower operations on downstream flow, stage, and sediment transport

    SciTech Connect

    Yin, S.C.L.; Tomasko, D.; Cho, H.E.; Williams, G.; McCoy, J.; Palmer, C.

    1996-11-01

    Hydropower operations at Flaming Gorge Dam, located on the Green River in Utah, can produce rapid downstream changes in flow and stage. These changes can in turn affect sediment transport and ecologic resources below the dam. To evaluate these effects, four hydropower operational scenarios with varying degrees of hydropower-release fluctuations were examined. This study demonstrates that the combined use of river-flow routing, water-surface profile, and sediment-transport models can provide useful information for evaluating the potential impacts of hydropower-operations on ecological and other resources downstream of the dam. Study results show that flow fluctuations may or may not persist for a long distance, depending on the initial magnitude of fluctuation and the duration of hydropower peaking. Stage fluctuations depend not only on flow fluctuations but also on river channel characteristics, such as channel width and longitudinal slope.

  7. Suspended sediment transport in the freshwater reach of the Hudson river estuary in eastern New York

    USGS Publications Warehouse

    Wall, G.R.; Nystrom, E.A.; Litten, S.

    2008-01-01

    Deposition of Hudson River sediment into New York Harbor interferes with navigation lanes and requires continuous dredging. Sediment dynamics at the Hudson estuary turbidity maximum (ETM) have received considerable study, but delivery of sediment to the ETM through the freshwater reach of the estuary has received relatively little attention and few direct measurements. An acoustic Doppler current profiler was positioned at the approximate limit of continuous freshwater to develop a 4-year time series of water velocity, discharge, suspended sediment concentration, and suspended sediment discharge. This data set was compared with suspended sediment discharge data collected during the same period at two sites just above the Hudson head-of-tide (the Federal Dam at Troy) that together represent the single largest source of sediment entering the estuary. The mean annual suspended sediment-discharge from the freshwater reach of the estuary was 737,000 metric tons. Unexpectedly, the total suspended sediment discharge at the study site in November and December slightly exceeded that observed during March and April, the months during which rain and snowmelt typically result in the largest sediment discharge to the estuary. Suspended sediment discharge at the study site exceeded that from the Federal Dam, even though the intervening reach appears to store significant amounts of sediment, suggesting that 30-40% of sediment discharge observed at the study site is derived from tributaries to the estuary between the Federal Dam and study site. A simple model of sediment entering and passing through the freshwater reach on a timescale of weeks appears reasonable during normal hydrologic conditions in adjoining watersheds; however, this simple model may dramatically overestimate sediment delivery during extreme tributary high flows, especially those at the end of, or after, the "flushing season" (October through April). Previous estimates of annual or seasonal sediment delivery

  8. Characterization of the efficiency of sedimentation basins downstream of harvested peat bogs

    NASA Astrophysics Data System (ADS)

    Samson-Do, Myriam; St-Hilaire, André

    2015-04-01

    Peat harvesting is a very lucrative industry in the provinces of Quebec and New-Brunswick (Canada). Peat enters in many potting mix used for horticulture. However, harvesting this resource has some impacts on the environment. First, industries need to drain the peat bog to dry the superficial layer. Then, it is harvested with industrial vacuums and the underlying layer is allowed to dry. The drained water is laden with suspended sediments (mostly organic peat fibers) that may affect biota of the stream where it is discharged. To counter the problem, this water does not go directly on the stream but first flows through a sedimentation basin, built to reduce suspended sediment loads. This work focuses on characterizing and eventually modeling the efficiency of those sedimentation basins. Seven basins were studied in Rivière-du-Loup, St-Valère and Escoumins (Quebec, Canada). They each have a different ratio basin area/drained area (4.7 10-4 to 20.3 10-4). To continuously monitor the sediment loads (calculated from sediment concentrations and discharge) entering and leaving basins, a nephelometer and a level logger were installed in the water column upstream and downstream of sedimentation basins. Their trapping efficiency was measured during the ice-free period (May to October) and for each significant rain event, since it is known that the rain and subsequent runoff induce most of the peat transport in and out of the basin. Results show that the event efficiency decreases as the basin is filled up with trapped sediments. For one basin, the efficiency was 85August. Trapping efficiency can be used as a tool to estimate basin dimensions. This has been done for municipal sedimentation ponds that trap minerals and will be adapted to the current context, where the dominant sediment is organic.

  9. Biomarkers in the freshwater bivalve Corbicula fluminea confined downstream a domestic landfill leachate discharge.

    PubMed

    de Oliveira, Luciana Fernandes; Santos, Caroline; Dos Reis Martinez, Claudia Bueno

    2016-07-01

    Landfills represent a severe environmental problem mainly due to the generation of leachates, and this study aimed to evaluate sublethal effects of a domestic landfill leachate in the freshwater bivalve Corbicula fluminea. Clams were submitted to in situ tests along a stream, at three sites, representing increasing distances from the leachate discharge (Pq1, Pq2, and Pq3), for 1, 5, and 15 days. The following biomarkers were analyzed in the gills and digestive glands: 7-ethoxyresorufin-O-deethylase (EROD) and glutathione S-transferase (GST) activities, multixenobiotic resistance mechanism (MXR), total antioxidant capacity (TAC), reactive oxygen species (ROS), and lipid peroxidation (LPO). Metallothionein (MT) content was determined in the gills and DNA damage in hemocytes. The mortality rate of animals during in situ tests was reduced as the distance from the leachate discharge source increased. On the other hand, biomarker results showed sublethal effects on C. fluminea confined at all sites of PqS. GST, TAC, ROS, and DNA damage were the most significant biomarkers for this species and should be considered for future monitoring and assessment of freshwater environments located in landfill areas. PMID:27040540

  10. Heavy metals in sediments of Ganga River: up- and downstream urban influences

    NASA Astrophysics Data System (ADS)

    Pandey, Jitendra; Singh, Rachna

    2015-09-01

    Bottom sediment in a river often acts as a sink and indicator of changes in water column and magnitude of anthropogenic influences through air and watersheds. Heavy metal concentration in sediments of Ganga River was studied along a 37-km stretch to assess whether there is a significant difference between sites situated upstream and downstream of Varanasi urban core. Metal concentration increased consistently along the study gradient, indicating the influence of urban sources. Concentration in the river sediment was found highest for Fe followed by Mn, Zn, Cr, Cu, Ni, Pb, and Cd. Mann-Kendall trend analysis showed marked seasonality in the concentration with values being highest in summer and lowest in rainy season. Enrichment factor revealed severe enrichment of Cd and Pb at downstream sites, and principal component analysis segregated sites into four distinct groups indicating source relationships. Concentrations of Cd, Pb, Ni, Cu, and Cr did exceed WHO standards. The study has relevance designing control measures and action plans for reducing sediment contamination in anthropogenic impacted rivers.

  11. IMPACTS OF IRON, NUTRIENTS, AND MINERAL FINES ON ANAEROBIC BIODEGRADATION OF CANOLA OIL IN FRESHWATER SEDIMENTS

    EPA Science Inventory

    Factors affecting anaerobic biodegradation kinetics of canola oil in freshwater sediments were investigated. An optimum dose of ferric hydroxide (10.5 g Fe(III)·kg-1 sediment) was found to stimulate anaerobic biodegradation of canola oil (18.6 g oil kg-1). ...

  12. Fractionation of mercury in sediments from coastal zone inundated by tsunami and in freshwater sediments from the rivers.

    PubMed

    Boszke, Leonard; Astel, Aleksander

    2007-06-01

    The study was undertaken to compare the mobility and bioavailability of mercury in tsunami sediments from the coastal zone of Thailand left after the 26 December 2004 tsunami event and freshwater sediments from the Vistula and the Warta rivers in Poland. The mobility and bioavailability of mercury in these sediments were determined by sequential extraction method. The environmental similarity/differences were estimated by statistical tests and cluster imaging technique. The coastal post-tsunami sediments were characterized by higher contributions of organomercury species (median 14%) and mercury sulphide (75%) than the freshwater sediments (5.4-9.3% and 60-68%, respectively), however, the contributions of water-soluble fraction (0.6%) and mercury bound to humic matter (7.6%) in the former was lower. In the river sediments the contributions of water-soluble mercury and mercury bound to humic matter were: 2.0-5.7% and 16-24%, respectively. The contributions of acid-soluble mercury were generally very low, but relatively higher in the post-tsunami sediments (0.7%) than in the freshwater sediments (0.3-0.4%). PMID:17558764

  13. Gully development in Pavon Creeks: Downstream sediment supply and sub-basin restoration

    NASA Astrophysics Data System (ADS)

    Pearce, S.; McKee, L. J.

    2011-12-01

    Sediment supply in watersheds is a function of geology, climate, and land use. Small watersheds in the Coast Ranges of California can provide large volumes of sediment to downstream waterbodies due to the active tectonic setting, the Mediterranean climate, and the history of intense land use. The Pavon Creeks sub-basin, a 1.1 km2 tributary to Pinole Creek which drains to San Francisco Bay, California, currently provides a large supply of fine-grained sediment to the detriment of creek function and native species habitat. The sub-basin is situated near the active Hayward Fault Zone, is underlain by highly erosive shales and siltstones, and has experienced over 100 years of cattle grazing. Despite only comprising 3% of the total watershed area, the Pavon Creeks sub-basin has been identified as one of the largest sources of fine sediment within the Pinole Creek watershed. To protect creek function and habitat, watershed stakeholders have prioritized preventing excess fine sediment delivery to Pinole Creek. The sub-basin includes four small ephemeral gully channels that are primarily actively eroding, downcutting, and extending over their length, and secondarily aggrading over a shorter localized reach. Field-based geomorphic data including channel cross-sections, longitudinal profiles, bank pins, and headcut monitoring have documented channel incision, erosion, and lengthening of the channel network over six years. During Water Year 2006, the first and wettest year of measurements, we observed maximum rates of incision of 0.75 m, lateral bank erosion of 2.5 m, and gully extension of 16.3 m. Annual repeat surveys show continued gully evolution, and allowed for quantitative assessment of incision, aggradation, and extension rates over this time period, as well as eroded sediment volume. We found that the largest storm events of a season cause the greatest instantaneous amount of change in the sub-basin, but cumulative seasonal rainfall determines the total amount and

  14. Geomorphic analysis of the river response to sedimentation downstream of Mount Rainier, Washington

    USGS Publications Warehouse

    Czuba, Jonathan A.; Magirl, Christopher S.; Czuba, Christiana R.; Curran, Christopher A.; Johnson, Kenneth H.; Olsen, Theresa D.; Kimball, Halley K.; Gish, Casey C.

    2012-01-01

    A study of the geomorphology of rivers draining Mount Rainier, Washington, was completed to identify sources of sediment to the river network; to identify important processes in the sediment delivery system; to assess current sediment loads in rivers draining Mount Rainier; to evaluate if there were trends in streamflow or sediment load since the early 20th century; and to assess how rates of sedimentation might continue into the future using published climate-change scenarios. Rivers draining Mount Rainier carry heavy sediment loads sourced primarily from the volcano that cause acute aggradation in deposition reaches as far away as the Puget Lowland. Calculated yields ranged from 2,000 tonnes per square kilometer per year [(tonnes/km2)/yr] on the upper Nisqually River to 350 (tonnes/km2)/yr on the lower Puyallup River, notably larger than sediment yields of 50–200 (tonnes/km2)/yr typical for other Cascade Range rivers. These rivers can be assumed to be in a general state of sediment surplus. As a result, future aggradation rates will be largely influenced by the underlying hydrology carrying sediment downstream. The active-channel width of rivers directly draining Mount Rainier in 2009, used as a proxy for sediment released from Mount Rainier, changed little between 1965 and 1994 reflecting a climatic period that was relatively quiet hydrogeomorphically. From 1994 to 2009, a marked increase in geomorphic disturbance caused the active channels in many river reaches to widen. Comparing active-channel widths of glacier-draining rivers in 2009 to the distance of glacier retreat between 1913 and 1994 showed no correlation, suggesting that geomorphic disturbance in river reaches directly downstream of glaciers is not strongly governed by the degree of glacial retreat. In contrast, there was a correlation between active-channel width and the percentage of superglacier debris mantling the glacier, as measured in 1971. A conceptual model of sediment delivery processes

  15. Sediment transport patterns and climate change: the downstream Tuul River case study, Northern Mongolia.

    NASA Astrophysics Data System (ADS)

    Pietroń, Jan; Jarsjö, Jerker

    2014-05-01

    Ongoing changes in the Central Asian climate including increasing temperatures can influence the hydrological regimes of rivers and the waterborne transport of sediments. Changes in the latter, especially in combination with adverse human activities, may severely impact water quality and aquatic ecosystems. However, waterborne transport of sediments is a result of complex processes and varies considerably between, and even within, river systems. There is therefore a need to increase our general knowledge about sediment transport under changing climate conditions. The Tuul River, the case site of this study, is located in the upper part of the basin of the Selenga River that is the main tributary to Lake Baikal, a UNESCO World Heritage Site. Like many other rivers located in the steppes of Northern Mongolia, the Tuul River is characterized by a hydrological regime that is not disturbed by engineered structures such as reservoirs and dams. However, the water quality of the downstream Tuul River is increasingly affected by adverse human activities - including placer gold mining. The largest contribution to the annual river discharge occurs during the relatively warm period in May to August. Typically, there are numerous rainfall events during this period that cause considerable river flow peaks. Parallel work has furthermore shown that due to climate change, the daily variability of discharge and numbers of peak flow events in the Tuul River Basin has increased during the past 60 years. This trend is expected to continue. We here aim at increasing our understanding of future sediment transport patterns in the Tuul River, specifically considering the scenario that peak flow events may become more frequent due to climate change. We use a one-dimensional sediment transport model of the downstream reach of the river to simulate natural patterns of sediment transport for a recent hydrological year. In general, the results show that sediment transport varies considerably

  16. Evaluating physical and biological influences on sedimentation in a tidal freshwater marsh with 7Be

    NASA Astrophysics Data System (ADS)

    Palinkas, Cindy M.; Engelhardt, Katharina A. M.; Cadol, Dan

    2013-09-01

    Key differences exist between tidal fresh- and saltwater marshes, such as the relative importance of mineral versus organic sedimentation and plant species diversity, that likely result in different drivers of sedimentation. In tidal freshwater marshes, we hypothesize that vegetation composition, along with physical marsh features (i.e., elevation and tidal channels), play a critical role in sedimentation. This hypothesis is evaluated in Dyke Marsh Preserve (Potomac River, VA, USA) by examining sediment character (grain size, organic content) and deposition rates across the marsh in spring and summer 2010 and 2011. 7Be is especially well suited to capture seasonal sedimentation patterns owing to its short half-life (53.3 d) and ability to assess both sediment deposition and erosion. However, its use in marshes can be challenging, especially due the presence of vegetation. In this study, 7Be-derived sedimentation rates are compared with sediment deposition observed on ceramic tiles to assess its utility in tidal freshwater marshes, and biophysical influences on sediment deposition are examined through statistical models. 7Be- and tile-derived sedimentation rates show similar spatial and temporal patterns, with highest rates occurring at sites closer to tidal channels, highlighting the importance of sediment availability. In addition, complex feedbacks between sedimentation and the plant community are discussed.

  17. Methods for measuring the toxicity and bioaccumulation of sediment-associated contaminants with freshwater invertebrates

    SciTech Connect

    Not Available

    1994-06-01

    The procedures are described for testing freshwater organisms in the laboratory to evaluate the toxicity or bioaccumulation of contaminants associated with whole sediments. Sediments may be collected from the field or spiked with compounds in the laboratory. Toxicity methods are outlined for two organisms, the amphipod Hyalella azteca and the midge Chironomus tentans. The toxicity tests are conducted for 10 d in 300 ml chambers containing 100 ml of sediment and 175 ml of overlying water. Overlying water is renewed daily and test organisms are fed during the toxicity tests. The endpoint in the toxicity test with H. azteca is survival and the endpoints in the toxicity test with C. tentans are survival and growth. Procedures are primarily described for testing freshwater sediments; however, estaurine sediments (up to 15%) can also be tested with H. azteca. Guidance for conducting 28-d bioaccumulation tests with the oligochaete Lumbriculus variegatus is provided in the manual.

  18. Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems

    USGS Publications Warehouse

    MacDonald, D.D.; Ingersoll, C.G.; Berger, T.A.

    2000-01-01

    Numerical sediment quality guidelines (SQGs) for freshwater ecosystems have previously been developed using a variety of approaches. Each approach has certain advantages and limitations which influence their application in the sediment quality assessment process. In an effort to focus on the agreement among these various published SQGs, consensus-based SQGs were developed for 28 chemicals of concern in freshwater sediments (i.e., metals, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and pesticides). For each contaminant of concern, two SQGs were developed from the published SQGs, including a threshold effect concentration (TEC) and a probable effect concentration (PEC). The resultant SQGs for each chemical were evaluated for reliability using matching sediment chemistry and toxicity data from field studies conducted throughout the United States. The results of this evaluation indicated that most of the TECs (i.e., 21 of 28) provide an accurate basis for predicting the absence of sediment toxicity. Similarly, most of the PECs (i.e., 16 of 28) provide an accurate basis for predicting sediment toxicity. Mean PEC quotients were calculated to evaluate the combined effects of multiple contaminants in sediment. Results of the evaluation indicate that the incidence of toxicity is highly correlated to the mean PEC quotient (R2 = 0.98 for 347 samples). It was concluded that the consensus-based SQGs provide a reliable basis for assessing sediment quality conditions in freshwater ecosystems.

  19. Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems.

    PubMed

    MacDonald, D D; Ingersoll, C G; Berger, T A

    2000-07-01

    Numerical sediment quality guidelines (SQGs) for freshwater ecosystems have previously been developed using a variety of approaches. Each approach has certain advantages and limitations which influence their application in the sediment quality assessment process. In an effort to focus on the agreement among these various published SQGs, consensus-based SQGs were developed for 28 chemicals of concern in freshwater sediments (i.e., metals, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and pesticides). For each contaminant of concern, two SQGs were developed from the published SQGs, including a threshold effect concentration (TEC) and a probable effect concentration (PEC). The resultant SQGs for each chemical were evaluated for reliability using matching sediment chemistry and toxicity data from field studies conducted throughout the United States. The results of this evaluation indicated that most of the TECs (i.e., 21 of 28) provide an accurate basis for predicting the absence of sediment toxicity. Similarly, most of the PECs (i.e., 16 of 28) provide an accurate basis for predicting sediment toxicity. Mean PEC quotients were calculated to evaluate the combined effects of multiple contaminants in sediment. Results of the evaluation indicate that the incidence of toxicity is highly correlated to the mean PEC quotient (R(2) = 0.98 for 347 samples). It was concluded that the consensus-based SQGs provide a reliable basis for assessing sediment quality conditions in freshwater ecosystems. PMID:10790498

  20. The effect of manipulations of freshwater sediments on responses of benthic invertebrates in whole-sediment toxicity tests

    SciTech Connect

    Day, K.E.; Kirby, R.S.; Reynoldson, T.B.

    1995-08-01

    Manipulations of freshwater sediment were performed to remove indigenous organisms prior to conducting toxicity tests with three species of benthic invertebrates. The effects of these treatments on end points in bioassays were compared within and between two sediments, i.e., a ``clean`` sediment and a ``contaminated`` sediment. In addition, the effects of manipulations on the physicochemical structure of the two sediments and the presence of metals, PAHs, and PCBs in the contaminated sediment were examined. The amphipod Hyalella azteca was most sensitive to the manipulations and had low survival in sediment that was sterilized. Growth (milligrams dry weight per individual) was affected by the presence of contaminants. Survival of Chironomus riparius was not affected by any manipulation but was reduced by contaminants as well as indigenous organisms. Growth of C. riparius was higher in autoclaved sediment but lower in sediment containing endemic tubificid worms. Production of young by Tubifex tubifex increased in sediment that was irradiated, possibly due to increased detrital material. Particle size distribution, metals, nutrients, and PAHs varied little as a function of manipulation; however, sieving of sediment through 250-{micro}m mesh did reduce percent total organic carbon (TOC), percent loss on ignition (LOI), and concentrations of some PCBs in either clean or contaminated sediment. Manipulation of sediments to remove endemic species should be determined on a case-by-case basis and is specific to the organisms used in toxicity tests.

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

    USGS Publications Warehouse

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

    2010-01-01

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

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

    PubMed

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

    2016-01-01

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

  3. Geomorphic analysis of the river response to sedimentation downstream of Mount Rainier, Washington

    USGS Publications Warehouse

    Czuba, Jonathan A.; Magirl, Christopher S.; Czuba, Christiana R.; Curran, Christopher A.; Johnson, Kenneth H.; Olsen, Theresa D.; Kimball, Halley K.; Gish, Casey C.

    2012-01-01

    A study of the geomorphology of rivers draining Mount Rainier, Washington, was completed to identify sources of sediment to the river network; to identify important processes in the sediment delivery system; to assess current sediment loads in rivers draining Mount Rainier; to evaluate if there were trends in streamflow or sediment load since the early 20th century; and to assess how rates of sedimentation might continue into the future using published climate-change scenarios. Rivers draining Mount Rainier carry heavy sediment loads sourced primarily from the volcano that cause acute aggradation in deposition reaches as far away as the Puget Lowland. Calculated yields ranged from 2,000 tonnes per square kilometer per year [(tonnes/km2)/yr] on the upper Nisqually River to 350 (tonnes/km2)/yr on the lower Puyallup River, notably larger than sediment yields of 50–200 (tonnes/km2)/yr typical for other Cascade Range rivers. These rivers can be assumed to be in a general state of sediment surplus. As a result, future aggradation rates will be largely influenced by the underlying hydrology carrying sediment downstream. The active-channel width of rivers directly draining Mount Rainier in 2009, used as a proxy for sediment released from Mount Rainier, changed little between 1965 and 1994 reflecting a climatic period that was relatively quiet hydrogeomorphically. From 1994 to 2009, a marked increase in geomorphic disturbance caused the active channels in many river reaches to widen. Comparing active-channel widths of glacier-draining rivers in 2009 to the distance of glacier retreat between 1913 and 1994 showed no correlation, suggesting that geomorphic disturbance in river reaches directly downstream of glaciers is not strongly governed by the degree of glacial retreat. In contrast, there was a correlation between active-channel width and the percentage of superglacier debris mantling the glacier, as measured in 1971. A conceptual model of sediment delivery processes

  4. Development of a bioavailability-based risk assessment approach for nickel in freshwater sediments.

    PubMed

    Schlekat, Christian E; Garman, Emily R; Vangheluwe, Marnix Lu; Burton, G Allen

    2016-10-01

    To assess nickel (Ni) toxicity and behavior in freshwater sediments, a large-scale laboratory and field sediment testing program was conducted. The program used an integrative testing strategy to generate scientifically based threshold values for Ni in sediments and to develop integrated equilibrium partitioning-based bioavailability models for assessing risks of Ni to benthic ecosystems. The sediment testing program was a multi-institutional collaboration that involved extensive laboratory testing, field validation of laboratory findings, characterization of Ni behavior in natural and laboratory conditions, and examination of solid phase Ni speciation in sediments. The laboratory testing initiative was conducted in 3 phases to satisfy the following objectives: 1) evaluate various methods for spiking sediments with Ni to optimize the relevance of sediment Ni exposures; 2) generate reliable ecotoxicity data by conducting standardized chronic ecotoxicity tests using 9 benthic species in sediments with low and high Ni binding capacity; and, 3) examine sediment bioavailability relationships by conducting chronic ecotoxicity testing in sediments that showed broad ranges of acid volatile sulfides, organic C, and Fe. A subset of 6 Ni-spiked sediments was deployed in the field to examine benthic colonization and community effects. The sediment testing program yielded a broad, high quality data set that was used to develop a Species Sensitivity Distribution for benthic organisms in various sediment types, a reasonable worst case predicted no-effect concentration for Ni in sediment (PNECsediment ), and predictive models for bioavailability and toxicity of Ni in freshwater sediments. A bioavailability-based approach was developed using the ecotoxicity data and bioavailability models generated through the research program. The tiered approach can be used to fulfill the outstanding obligations under the European Union (EU) Existing Substances Risk Assessment, EU Registration

  5. Natural stressors in uncontaminated sediments of shallow freshwaters: the prevalence of sulfide, ammonia, and reduced iron.

    PubMed

    Kinsman-Costello, Lauren E; O'Brien, Jonathan M; Hamilton, Stephen K

    2015-03-01

    Potentially toxic levels of 3 naturally occurring chemical stressors (dissolved sulfide, ammonia, and iron) can appear in freshwater sediments, although their roles in shaping ecosystem structure (i.e., plant and animal communities) and function (e.g., biologically mediated elemental cycles) have received little study. The present critical review discusses the prevalence and ecological effects of potentially toxic concentrations of sulfide, ammonia, and iron in uncontaminated freshwater sediments, including a review of the literature as well as a case study presenting previously unpublished data on sediment porewaters from a diverse set of shallow (<2 m) freshwater ecosystems in southwest Michigan, USA. Measured concentrations are compared with surface water quality criteria established by the US Environmental Protection Agency (USEPA) and with acute and chronic toxic thresholds in the published literature, where available. Based on USEPA criteria for aquatic life for these 3 stressors, the benthic environment of almost every freshwater ecosystem sampled was theoretically stressful to some component of aquatic life in some area or at some time (i.e., in at least 1 sample), and 54% of samples exceeded more than 1 criterion simultaneously. Organismal tolerances to chemical stressors vary, so the observed concentrations are likely shaping benthic animal communities and influencing rates of ecosystem processes. Consideration of the role of natural chemical stressors is important in shaping freshwater benthic environments and in developing bioassessments, restoration goals, and remediation plans. Environ Toxicol Chem 2015;34:467-479. © 2014 SETAC.

  6. ANAEROBIC BIODEGRADATION OF VEGETABLE OIL AND ITS METABOLIC INTERMEDIATES IN OIL-ENRICHED FRESHWATER SEDIMENTS

    EPA Science Inventory

    Anaerobic biodegradation of vegetable oil in freshwater sediments is strongly inhibited by high concentrations of oil, but the presence of ferric hydroxide relieves the inhibition. The effect of ferric hydroxide is not due to physical or chemical interactions with long-chain fatt...

  7. COSOLVENT EFFECTS ON PHENANTHRENE SORPTION-DESORPTION ON A FRESH-WATER SEDIMENT

    EPA Science Inventory

    This study evaluated the effects of the water-miscible cosolvent methanol on the sorption-desorption of phenanthrene by the natural organic matter (NOM) of a fresh-water sediment. A biphasic pattern was observed in the relationship between the log of the carbon-normalized sorpti...

  8. Tolerance of freshwater test organisms to formulated sediments for use as control materials in whole-sediment toxicity tests

    SciTech Connect

    Kemble, N.E.; Dwyer, F.J.; Ingersoll, C.G.; Dawson, T.D.; Norberg-King, T.J.

    1999-02-01

    A method is described for preparing formulated sediments for use in toxicity testing. Ingredients used to prepare formulated sediments included commercially available silt, clay, sand, humic acid, dolomite, and {alpha}-cellulose (as a source of organic carbon). {alpha}-Cellulose was selected as the source of organic carbon because it is commercially available, consistent from batch to batch, and low in contaminant concentrations. The tolerance of freshwater test organisms to formulated sediments for use as control materials in whole-sediment toxicity testing was evaluated. Sediment exposures were conducted for 10 d with the amphipod Hyalella azteca, the midges Chironomus riparius and C. tentans, and the oligochaete Lumbriculus variegatus and for 28 d with H. azteca. Responses of organisms in formulated sediments was compared with a field-collected control sediment that has routinely been used to determine test acceptability. Tolerance of organisms to formulated sediments was evaluated by determining responses to varying levels of {alpha}-cellulose, to varying levels of grain size, to evaluation of different food types, or to evaluation of different sources of overlying water. In the 10-d exposures, survival of organisms exposed to the formulated sediments routinely met or exceeded the responses of test organisms exposed to the control sediment and routinely met test acceptability criteria required in standard methods. Growth of amphipods and oligochaetes in 10-d exposures with formulated sediment was often less than growth of organisms in the field-collected control sediment. Additional research is needed, using the method employed to prepare formulated sediment, to determine if conditioning formulated sediments before starting 10-d tests would improve the growth of amphipods. In the 28-d exposures, survival of H. azteca was low when reconstituted water was used as the source of overlying water. However, when well water was used as the source of overlying water in

  9. Tolerance of freshwater test organisms to formulated sediments for use as control materials in whole-sediment toxicity tests

    USGS Publications Warehouse

    Kemble, N.E.; Dwyer, F.J.; Ingersoll, C.G.; Dawson, T.D.; Norberg-King, T. J.

    1999-01-01

    A method is described for preparing formulated sediments for use in toxicity testing. Ingredients used to prepare formulated sediments included commercially available silt, clay, sand, humic acid, dolomite, and ??- cellulose (as a source of organic carbon). ??-Cellulose was selected as the source of organic carbon because it is commercially available, consistent from batch to batch, and low in contaminant concentrations. The tolerance of freshwater test organisms to formulated sediments for use as control materials in whole-sediment toxicity testing was evaluated. Sediment exposures were conducted for 10 d with the amphipod Hyalella azteca, the midges Chironomus riparius and C. tentans, and the oligochaete Lumbriculus variegatus and for 28 d with H. azteca. Responses of organisms in formulated sediments was compared with a field-collected control sediment that has routinely been used to determine test acceptability. Tolerance of organisms to formulated sediments was evaluated by determining responses to varying levels of ??-cellulose, to varying levels of grain size, to evaluation of different food types, or to evaluation of different sources of overlying water. In the 10-d exposures, survival of organisms exposed to the formulated sediments routinely met or exceeded the responses of test organisms exposed to the control sediment and routinely met test acceptability criteria required in standard methods. Growth of amphipods and oligochaetes in 10-d exposures with formulated sediment was often less than growth of organisms in the field-collected control sediment. Additional research is needed, using the method employed to prepare formulated sediment, to determine if conditioning formulated sediments before starting 10-d tests would improve the growth of amphipods. In the 28-d exposures, survival of H. azteca was low when reconstituted water was used as the source of overlying water. However, when well water was used as the source of overlying water in 28-d exposures

  10. Chronic toxicity of nickel-spiked freshwater sediments: variation in toxicity among eight invertebrate taxa and eight sediments

    USGS Publications Warehouse

    Besser, John M.; Brumbaugh, William G.; Ingersoll, Christopher G.; Ivey, Chris D.; Kunz, James L.; Kemble, Nile E.; Schlekat, Christian E.; Garman, Emily R.

    2013-01-01

    This study evaluated the chronic toxicity of Ni-spiked freshwater sediments to benthic invertebrates. A 2-step spiking procedure (spiking and sediment dilution) and a 2-stage equilibration period (10 wk anaerobic and 1 wk aerobic) were used to spike 8 freshwater sediments with wide ranges of acid-volatile sulfide (AVS; 0.94–38 µmol/g) and total organic carbon (TOC; 0.42–10%). Chronic sediment toxicity tests were conducted with 8 invertebrates (Hyalella azteca, Gammarus pseudolimnaeus, Chironomus riparius, Chironomus dilutus, Hexagenia sp., Lumbriculus variegatus, Tubifex tubifex, and Lampsilis siliquoidea) in 2 spiked sediments. Nickel toxicity thresholds estimated from species-sensitivity distributions were 97 µg/g and 752 µg/g (total recoverable Ni; dry wt basis) for sediments with low and high concentrations of AVS and TOC, respectively. Sensitive species were tested with 6 additional sediments. The 20% effect concentrations (EC20s) for Hyalella and Gammarus, but not Hexagenia, were consistent with US Environmental Protection Agency benchmarks based on Ni in porewater and in simultaneously extracted metals (SEM) normalized to AVS and TOC. For Hexagenia, sediment EC20s increased at less than an equimolar basis with increased AVS, and toxicity occurred in several sediments with Ni concentrations in SEM less than AVS. The authors hypothesize that circulation of oxygenated water by Hexagenia led to oxidation of AVS in burrows, creating microenvironments with high Ni exposure. Despite these unexpected results, a strong relationship between Hexagenia EC20s and AVS could provide a basis for conservative site-specific sediment quality guidelines for Ni.

  11. Fine sediment as environmental stressor affecting freshwater mussel behavior and ecosystem services.

    PubMed

    Lummer, Eva-Maria; Auerswald, Karl; Geist, Juergen

    2016-11-15

    Fine sediment pollution is considered a major stressor for aquatic ecosystems and their biodiversity. In particular, fine sediments have been suggested to play a crucial role in the declines of freshwater mussels which are considered keystone fauna of streams and rivers. Whereas the effects of deposited fine sediments on recruitment failure are well known, effects of suspended fine sediments on adult mussel behavior are less studied. Therefore the aim of this study was to investigate the effects of fine sediment exposure on freshwater mussel behavior and on mussel-dependent ecosystem services. Unio pictorum mussels were used to test three behavioral endpoints: Hall activity, transition frequency and relative water clearance rate. Mussels were exposed to fine sediments of different particle size classes (<45μm, 45-63μm, 63-125μm) and different concentration (0-10gL(-1)) of the smallest particle size class. Hall sensor technology and turbidity measurements were used to detect mussel behavior in presence of suspended sediments. Results revealed that mussels improve clearance of suspended particles out of the water column by 35%, independent of particle size class and concentration. Transition frequency was determined an unsuitable behavioral endpoint for non-soluble substances. Contrary to previous studies, we could demonstrate that fine sediments do not interfere with filtration by mussels and that mussels have a great influence on water purification, providing a valuable ecosystem service. PMID:27422724

  12. Sediment Ammonia-Oxidizing Microorganisms in Two Plateau Freshwater Lakes at Different Trophic States.

    PubMed

    Yang, Yuyin; Zhang, Jingxu; Zhao, Qun; Zhou, Qiheng; Li, Ningning; Wang, Yilin; Xie, Shuguang; Liu, Yong

    2016-02-01

    Both ammonia-oxidizing archaea (AOA) and bacteria (AOB) can contribute to ammonia biotransformation in freshwater lake ecosystems. However, the factors shaping the distribution of sediment AOA and AOB in plateau freshwater lake remains unclear. The present study investigated sediment AOA and AOB communities in two freshwater lakes (hypertrophic Dianchi Lake and mesotrophic Erhai Lake) on the Yunnan Plateau (China). A remarkable difference in the abundance, diversity, and composition of sediment AOA and AOB communities was observed between Dianchi Lake and Erhai Lake. AOB usually outnumbered AOA in Dianchi Lake, but AOA showed the dominance in Erhai Lake. Organic matter (OM), total nitrogen (TN), and total phosphorus (TP) might be the key determinants of AOB abundance, while AOA abundance was likely influenced by the ration of OM to TN (C/N). AOA or AOB community structure was found to be relatively similar in the same lake. TN and TP might play important roles in shaping sediment AOA and AOB compositions in Dianchi Lake and Erhai Lake. Moreover, Nitrososphaera-like AOA were detected in Dianchi Lake. Nitrosospira- and Nitrosomonas-like AOB were dominant in Dianchi Lake and Erhai Lake, respectively. Sediment AOA and AOB communities in Dianchi Lake and Erhai Lake were generally regulated by trophic state. PMID:26111964

  13. Sediment Ammonia-Oxidizing Microorganisms in Two Plateau Freshwater Lakes at Different Trophic States.

    PubMed

    Yang, Yuyin; Zhang, Jingxu; Zhao, Qun; Zhou, Qiheng; Li, Ningning; Wang, Yilin; Xie, Shuguang; Liu, Yong

    2016-02-01

    Both ammonia-oxidizing archaea (AOA) and bacteria (AOB) can contribute to ammonia biotransformation in freshwater lake ecosystems. However, the factors shaping the distribution of sediment AOA and AOB in plateau freshwater lake remains unclear. The present study investigated sediment AOA and AOB communities in two freshwater lakes (hypertrophic Dianchi Lake and mesotrophic Erhai Lake) on the Yunnan Plateau (China). A remarkable difference in the abundance, diversity, and composition of sediment AOA and AOB communities was observed between Dianchi Lake and Erhai Lake. AOB usually outnumbered AOA in Dianchi Lake, but AOA showed the dominance in Erhai Lake. Organic matter (OM), total nitrogen (TN), and total phosphorus (TP) might be the key determinants of AOB abundance, while AOA abundance was likely influenced by the ration of OM to TN (C/N). AOA or AOB community structure was found to be relatively similar in the same lake. TN and TP might play important roles in shaping sediment AOA and AOB compositions in Dianchi Lake and Erhai Lake. Moreover, Nitrososphaera-like AOA were detected in Dianchi Lake. Nitrosospira- and Nitrosomonas-like AOB were dominant in Dianchi Lake and Erhai Lake, respectively. Sediment AOA and AOB communities in Dianchi Lake and Erhai Lake were generally regulated by trophic state.

  14. Effects of Methane Metabolism on Nitrification and Nitrous Oxide Production in Polluted Freshwater Sediment

    PubMed Central

    Roy, Réal; Knowles, Roger

    1994-01-01

    We report the effect of CH4 and of CH4 oxidation on nitrification in freshwater sediment from Hamilton Harbour, Ontario, Canada, a highly polluted ecosystem. Aerobic slurry experiments showed a high potential for aerobic N2O production in some sites. It was suppressed by C2H2, correlated to NO3- production, and stimulated by NH4+ concentration, supporting the hypothesis of a nitrification-dependent source for this N2O production. Diluted sediment slurries supplemented with CH4 (1 to 24 μM) showed earlier and enhanced nitrification and N2O production compared with unsupplemented slurries (≤1 μM CH4). This suggests that nitrification by methanotrophs may be significant in freshwater sediment under certain conditions. Suppression of nitrification was observed at CH4 concentrations of 84 μM and greater, possibly through competition for O2 between methanotrophs and NH4+ -oxidizing bacteria and/or competition for mineral N between these two groups of organisms. In Hamilton Harbour sediment, the very high CH4 concentrations (1.02 to 6.83 mM) which exist would probably suppress nitrification and favor NH4+ accumulation in the pore water. Indeed, NH4+ concentrations in Hamilton Harbour sediment are higher than those found in other lakes. We conclude that the impact of CH4 metabolism on N cycling processes in freshwater ecosystems should be given more attention. PMID:16349384

  15. Characterization of anaerobic heterotrophic bacteria isolated from freshwater lake sediments.

    PubMed

    Molongoski, J J; Klug, M J

    1976-01-01

    Strict anaerobic culture techniques were used to quantitatively and qualitatively evaluate the anaerobic heterotrophic bacteria present at the sediment-water interface of hyperutrophic Wintergreen Lake (Augusta, Mich.). Anaerobic plate counts remained constant from March through December, 1973, ranging from 2.4 X 10(6) to 5.7 X 10(6) organisms/g (dry weight) of sediment. The isolatable bacteria represented a small percentage of the total microbial community, which was shown by direct microscopic counts to be 2.0 X 10'' organisms/g (dry weight) of sediment during June and July. Bacteria of the genus Clostridium dominated the isolates obtained, accounting for 71.8% of the 960 isolates examined. A single species, Clostridium bifermentens, comprised 47.7% of the total. Additional bacterial groups and the percentage in which they were isolated included: Streptococcus sp. (10.8%), unidentified curved rods (9.5%y, gram-positive nonsporing rods (5.6%), and motile gram-negative rods (1.9%). Temperature growth studies demonstrated the ability of all the isolates to grow at in situ sediment temperatures. Gas-liqid radiochromatography was used to determine the soluble metabolic end products from [U-14C]glucose and a U-14C-labeled amino acid mixture by representative sedimentary clostridial isolates and by natural sediment microbial communities. At in situ temperatures the natural sediment microflora produced soluble fermentative end products characteristic of those elaborated by the clostridial isolates tested. These results are considered strong presumptive evidence that clostridia are actively metabolizing in the sediments of Wintergreen Lake.

  16. Sediment-phosphorus dynamics can shift aquatic ecology and cause downstream legacy effects after wildfire in large river systems.

    PubMed

    Emelko, Monica B; Stone, Micheal; Silins, Uldis; Allin, Don; Collins, Adrian L; Williams, Chris H S; Martens, Amanda M; Bladon, Kevin D

    2016-03-01

    Global increases in the occurrence of large, severe wildfires in forested watersheds threaten drinking water supplies and aquatic ecology. Wildfire effects on water quality, particularly nutrient levels and forms, can be significant. The longevity and downstream propagation of these effects as well as the geochemical mechanisms regulating them remain largely undocumented at larger river basin scales. Here, phosphorus (P) speciation and sorption behavior of suspended sediment were examined in two river basins impacted by a severe wildfire in southern Alberta, Canada. Fine-grained suspended sediments (<125 μm) were sampled continuously during ice-free conditions over a two-year period (2009-2010), 6 and 7 years after the wildfire. Suspended sediment samples were collected from upstream reference (unburned) river reaches, multiple tributaries within the burned areas, and from reaches downstream of the burned areas, in the Crowsnest and Castle River basins. Total particulate phosphorus (TPP) and particulate phosphorus forms (nonapatite inorganic P, apatite P, organic P), and the equilibrium phosphorus concentration (EPC0 ) of suspended sediment were assessed. Concentrations of TPP and the EPC0 were significantly higher downstream of wildfire-impacted areas compared to reference (unburned) upstream river reaches. Sediments from the burned tributary inputs contained higher levels of bioavailable particulate P (NAIP) - these effects were also observed downstream at larger river basin scales. The release of bioavailable P from postfire, P-enriched fine sediment is a key mechanism causing these effects in gravel-bed rivers at larger basin scales. Wildfire-associated increases in NAIP and the EPC0 persisted 6 and 7 years after wildfire. Accordingly, this work demonstrated that fine sediment in gravel-bed rivers is a significant, long-term source of in-stream bioavailable P that contributes to a legacy of wildfire impacts on downstream water quality, aquatic ecology, and

  17. Sediment-phosphorus dynamics can shift aquatic ecology and cause downstream legacy effects after wildfire in large river systems.

    PubMed

    Emelko, Monica B; Stone, Micheal; Silins, Uldis; Allin, Don; Collins, Adrian L; Williams, Chris H S; Martens, Amanda M; Bladon, Kevin D

    2016-03-01

    Global increases in the occurrence of large, severe wildfires in forested watersheds threaten drinking water supplies and aquatic ecology. Wildfire effects on water quality, particularly nutrient levels and forms, can be significant. The longevity and downstream propagation of these effects as well as the geochemical mechanisms regulating them remain largely undocumented at larger river basin scales. Here, phosphorus (P) speciation and sorption behavior of suspended sediment were examined in two river basins impacted by a severe wildfire in southern Alberta, Canada. Fine-grained suspended sediments (<125 μm) were sampled continuously during ice-free conditions over a two-year period (2009-2010), 6 and 7 years after the wildfire. Suspended sediment samples were collected from upstream reference (unburned) river reaches, multiple tributaries within the burned areas, and from reaches downstream of the burned areas, in the Crowsnest and Castle River basins. Total particulate phosphorus (TPP) and particulate phosphorus forms (nonapatite inorganic P, apatite P, organic P), and the equilibrium phosphorus concentration (EPC0 ) of suspended sediment were assessed. Concentrations of TPP and the EPC0 were significantly higher downstream of wildfire-impacted areas compared to reference (unburned) upstream river reaches. Sediments from the burned tributary inputs contained higher levels of bioavailable particulate P (NAIP) - these effects were also observed downstream at larger river basin scales. The release of bioavailable P from postfire, P-enriched fine sediment is a key mechanism causing these effects in gravel-bed rivers at larger basin scales. Wildfire-associated increases in NAIP and the EPC0 persisted 6 and 7 years after wildfire. Accordingly, this work demonstrated that fine sediment in gravel-bed rivers is a significant, long-term source of in-stream bioavailable P that contributes to a legacy of wildfire impacts on downstream water quality, aquatic ecology, and

  18. Patterns of short-term sedimentation in a freshwater created marsh.

    PubMed

    Harter, Sarah K; Mitsch, William J

    2003-01-01

    This study investigated different sedimentation measurement techniques and examined patterns of short-term sedimentation in two 1-ha replicate created freshwater marshes in central Ohio, USA. Short-term (one-year) sediment accumulation above feldspar, clay, glitter, and sand artificial marker horizons was compared at different water depths and distances from wetland inflow. A sediment budget was also constructed from turbidity and suspended sediment data for comparison with marker horizons. Glitter and sand marker horizons were the most successful for measuring sediment accumulation (81-100% marker recovery), while clay markers were completely unsuccessful. The sedimentation rate for both wetlands averaged 4.9 cm yr(-1) (36 kg m(-2) yr(-1)), and ranged from 1.82 to 9.23 cm yr(-1) (12.4 to 69.7 kg m(-2) yr(-1)). Sedimentation rates in deep, open water areas were significantly higher than in shallow, vegetated areas for both wetlands (t test, p < 0.05). However, observed sedimentation patterns may be attributed more to preferential flow through open water areas than to water depth or presence of vegetation. Contrary to the expected spatial distribution, sedimentation was highly variable within the wetlands, suggesting that bioturbation and turbulence may cause significant resuspension or that high hydrologic loads may distribute sediments throughout the basins. A sediment budget estimated sediment retention of approximately 740 g m(-2) yr(-1) per wetland (43% removal rate), yet gross sediment accumulation was 36,000 g m(-2) yr(-1) measured by marker horizons. These results suggest that erosive forces may have influenced sedimentation, but also may indicate problems with the sediment budget calculation methodology.

  19. Anaerobic Oxidation of Methane in Sediments of Lake Constance, an Oligotrophic Freshwater Lake▿

    PubMed Central

    Deutzmann, Jörg S.; Schink, Bernhard

    2011-01-01

    Anaerobic oxidation of methane (AOM) with sulfate as terminal electron acceptor has been reported for various environments, including freshwater habitats, and also, nitrate and nitrite were recently shown to act as electron acceptors for methane oxidation in eutrophic freshwater habitats. Radiotracer experiments with sediment material of Lake Constance, an oligotrophic freshwater lake, were performed to follow 14CO2 formation from 14CH4 in sediment incubations in the presence of different electron acceptors, namely, nitrate, nitrite, sulfate, or oxygen. Whereas 14CO2 formation without and with sulfate addition was negligible, addition of nitrate increased 14CO2 formation significantly, suggesting that AOM could be coupled to denitrification. Nonetheless, denitrification-dependent AOM rates remained at least 1 order of magnitude lower than rates of aerobic methane oxidation. Using molecular techniques, putative denitrifying methanotrophs belonging to the NC10 phylum were detected on the basis of the pmoA and 16S rRNA gene sequences. These findings show that sulfate-dependent AOM was insignificant in Lake constant sediments. However, AOM can also be coupled to denitrification in this oligotrophic freshwater habitat, providing first indications that this might be a widespread process that plays an important role in mitigating methane emissions. PMID:21551281

  20. Contemporary deposition and long-term accumulation of sediment and nutrients by tidal freshwater forested wetlands impacted by sea level rise

    USGS Publications Warehouse

    Noe, Gregory; Hupp, Cliff R.; Bernhardt, Christopher E.; Krauss, Ken W.

    2016-01-01

    Contemporary deposition (artificial marker horizon, 3.5 years) and long-term accumulation rates (210Pb profiles, ~150 years) of sediment and associated carbon (C), nitrogen (N), and phosphorus (P) were measured in wetlands along the tidal Savannah and Waccamaw rivers in the southeastern USA. Four sites along each river spanned an upstream-to-downstream salinification gradient, from upriver tidal freshwater forested wetland (TFFW), through moderately and highly salt-impacted forested wetlands, to oligohaline marsh downriver. Contemporary deposition rates (sediment, C, N, and P) were greatest in oligohaline marsh and lowest in TFFW along both rivers. Greater rates of deposition in oligohaline and salt-stressed forested wetlands were associated with a shift to greater clay and metal content that is likely associated with a change from low availability of watershed-derived sediment to TFFW and to greater availability of a coastal sediment source to oligohaline wetlands. Long-term accumulation rates along the Waccamaw River had the opposite spatial pattern compared to contemporary deposition, with greater rates in TFFW that declined to oligohaline marsh. Long-term sediment and elemental mass accumulation rates also were 3–9× lower than contemporary deposition rates. In comparison to other studies, sediment and associated nutrient accumulation in TFFW are lower than downriver/estuarine freshwater, oligohaline, and salt marshes, suggesting a reduced capacity for surface sedimentation (short-term) as well as shallow soil processes (long-term sedimentation) to offset sea level rise in TFFW. Nonetheless, their potentially large spatial extent suggests that TFFW have a large impact on the transport and fate of sediment and nutrients in tidal rivers and estuaries.

  1. Anaerobic versus aerobic degradation of dimethyl sulfide and methanethiol in anoxic freshwater sediments

    SciTech Connect

    Lomans, B.P.; Op den Camp, H.J.M.; Pol, A.; Vogels, G.D.

    1999-02-01

    Degradation of dimethyl sulfide and methanethiol in slurries prepared from sediments of minerotrophic peatland ditches were studied under various conditions. Maximal aerobic dimethyl sulfide-degrading capacities, measured in bottles shaken under an air atmosphere, were 10-fold higher than the maximal anaerobic degrading capacities determined from bottles shaken under N{sub 2} or H{sub 2} atmosphere. Incubations under experimental conditions which mimic the in situ conditions, however, revealed that aerobic degradation of dimethyl sulfide and methanethiol in freshwater sediments is low due to oxygen limitation. Inhibition studies with bromoethanesulfonic acid and sodium tungstate demonstrated that the degradation of dimethyl sulfide and methanethiol in these incubations originated mainly from methanogenic activity. Prolonged incubation under a H{sub 2} atmosphere resulted in lower dimethyl sulfide degradation rates. Kinetic analysis of the data resulted in apparent K{sub m} values (6 to 8 {micro}M) for aerobic dimethyl sulfide degradation which are comparable to those reported for Thiobacillus spp., Hyphomicrobium spp., and other methylotrophs. Apparent K{sub m} values determined for anaerobic degradation of dimethyl sulfide were of the same order of magnitude. The low apparent K{sub m} values obtained explain the low dimethyl sulfide and methanethiol concentrations in freshwater sediments that they reported previously. The observations point to methanogenesis as the major mechanism of dimethyl sulfide and methanethiol consumption in freshwater sediments.

  2. Distributions and biomass of benthic ciliates, foraminifera and amoeboid protists in marine, brackish, and freshwater sediments.

    PubMed

    Lei, Yan-Li; Stumm, Karen; Wickham, Stephen A; Berninger, Ulrike-G

    2014-01-01

    The quantitative importance of ciliates, foraminifers, and amoebae was investigated in marine, brackish, and freshwater sediments from 15 littoral stations. Total protozoan communities were usually dominated by ciliates in term of abundance, while amoebae often dominated in terms of biomass. Applying the biomass-metabolic rate equation, ciliates, amoebae, and foraminifera were estimated to contribute 66% of the total abundance and 33% of the biomass, but up to 55% of the combined metabolic rate to the micro- and meiobenthos in the 15 sediments. Statistical analyses using ciliate data demonstrated: (1) species composition and community structures represented significant differences between freshwater and marine/brackish sediments, and subsequently between temperate and arctic sampling sites; (2) the occurrence of dominant ciliates and their allocation to feeding types indicated that herbivory was the most common feeding strategy in these sediments; (3) multivariate analyses showed all of the tested environmental factors (temperature, salinity, silt/clay, carbon, nitrogen, and chlorophyll a) to be important to varying degrees, but especially the combination of salinity, temperature, and silt/clay. Multiple factor effects or comprehensive influences might be important in regulating the distribution of protozoa in sediments. The importance of protozoa in sediment systems and the potential ecological significance of cysts are discussed. PMID:24919761

  3. Heavy metal accumulation in sediment and freshwater fish in U.S. Arctic lakes

    SciTech Connect

    Allen-Gil, S.M.; Gubala, C.P.; Landers, D.H.; Lasorsa, B.K.; Crecelius, E.A.; Curtis, L.R.

    1997-04-01

    Metal concentrations in sediment and two species of freshwater fish (lake trout [Salvelinus namaycush], and grayling [Thymallus arcticus]) were examined in four Arctic lakes in Alaska. Concentrations of several metals were naturally high in the sediment relative to uncontaminated lakes in other Arctic regions and more temperate locations. For example, concentrations of Hg and Ni were 175 ng/g and 250 ng/g dry weight, respectively, in Feniak Lake surface sediment. If any anthropogenic enrichment has occurred, it is not distinguishable from background variability based on surface sediment to down core comparisons. With the exception of Hg, the site rank order of metal concentrations (Cu, Cd, Ni, Pb, and Zn) in sediment and freshwater fish tissue among lakes is not consistent. This suggests that a number of physical, chemical, and physiological parameters mediate metal bioavailability and uptake in these systems. Maximum concentrations of most metals in fish from this study are equal to or higher than those collected from remote Arctic lakes and rivers in Canada, Finland, and Russia. Muscle Hg concentrations in excess of 1 {micro}g/g wet weight were observed in lake trout from Feniak Lake, which has no identified Hg source other than naturally Hg-enriched sediments. Fish diet seems to influence some heavy metal burdens, as evidenced by the higher concentrations of some metals in lake trout compared to grayling, and differences among lakes for lake trout. Cadmium, Cu, and Zn burdens were higher in lakes where snails were consumed by trout compared to lakes without snails.

  4. Evidence for anaerobic ammonium oxidation process in freshwater sediments of aquaculture ponds.

    PubMed

    Shen, Li-dong; Wu, Hong-sheng; Gao, Zhi-qiu; Ruan, Yun-jie; Xu, Xiang-hua; Li, Ji; Ma, Shi-jie; Zheng, Pei-hui

    2016-01-01

    The anaerobic ammonium oxidation (anammox) process, which can simultaneously remove ammonium and nitrite, both toxic to aquatic animals, can be very important to the aquaculture industry. Here, the presence and activity of anammox bacteria in the sediments of four different freshwater aquaculture ponds were investigated by using Illumina-based 16S rRNA gene sequencing, quantitative PCR assays and (15)N stable isotope measurements. Different genera of anammox bacteria were detected in the examined pond sediments, including Candidatus Brocadia, Candidatus Kuenenia and Candidatus Anammoxoglobus, with Candidatus Brocadia being the dominant anammox genus. Quantitative PCR of hydrazine synthase genes showed that the abundance of anammox bacteria ranged from 5.6 × 10(4) to 2.1 × 10(5) copies g(-1) sediment in the examined ponds. The potential anammox rates ranged between 3.7 and 19.4 nmol N2 g(-1) sediment day(-1), and the potential denitrification rates varied from 107.1 to 300.3 nmol N2 g(-1) sediment day(-1). The anammox process contributed 1.2-15.3% to sediment dinitrogen gas production, while the remainder would be due to denitrification. It is estimated that a total loss of 2.1-10.9 g N m(-2) per year could be attributed to the anammox process in the examined ponds, suggesting that this process could contribute to nitrogen removal in freshwater aquaculture ponds.

  5. Distributions and biomass of benthic ciliates, foraminifera and amoeboid protists in marine, brackish, and freshwater sediments.

    PubMed

    Lei, Yan-Li; Stumm, Karen; Wickham, Stephen A; Berninger, Ulrike-G

    2014-01-01

    The quantitative importance of ciliates, foraminifers, and amoebae was investigated in marine, brackish, and freshwater sediments from 15 littoral stations. Total protozoan communities were usually dominated by ciliates in term of abundance, while amoebae often dominated in terms of biomass. Applying the biomass-metabolic rate equation, ciliates, amoebae, and foraminifera were estimated to contribute 66% of the total abundance and 33% of the biomass, but up to 55% of the combined metabolic rate to the micro- and meiobenthos in the 15 sediments. Statistical analyses using ciliate data demonstrated: (1) species composition and community structures represented significant differences between freshwater and marine/brackish sediments, and subsequently between temperate and arctic sampling sites; (2) the occurrence of dominant ciliates and their allocation to feeding types indicated that herbivory was the most common feeding strategy in these sediments; (3) multivariate analyses showed all of the tested environmental factors (temperature, salinity, silt/clay, carbon, nitrogen, and chlorophyll a) to be important to varying degrees, but especially the combination of salinity, temperature, and silt/clay. Multiple factor effects or comprehensive influences might be important in regulating the distribution of protozoa in sediments. The importance of protozoa in sediment systems and the potential ecological significance of cysts are discussed.

  6. Interaction of acetogens and methanogens in anaerobic freshwater sediments.

    PubMed

    Jones, J G; Simon, B M

    1985-04-01

    Anaerobic decomposition processes in the profundal sediments of Blelham Tarn (English Lake District) are often limited during late summer by the input of organic carbon. The concentration of acetate in the interstitial water fell from about 100 microM (immediately after sedimentation of the spring diatom bloom) to a relatively constant value of about 20 microM in late summer, during which acetate utilization appeared to be balanced by production. Addition of chloroform and molybdate caused an accumulation of cold acetate in large sediment cores and of [14C]acetate in small cores to which [14C]bicarbonate had been added. In both cases chloroform caused the greater accumulation, implying that acetoclastic methanogens were the more active consumers. The conversion of 14CO2 to [14C]acetate was inversely related, with depth, to its conversion to 14CH4. Methanogenesis from CO2 decreased during late summer, whereas acetogenesis and acetoclastic methanogenesis increased over the same time period. The production of acetate from CO2 was generally equivalent to less than 10% of the acetate carbon utilized but could be as high as 25% of that value. Hydrogen consumption by acetogens could be as high as 50% of that utilized in methanogenesis. The role of acetogenic bacteria in anaerobic processes may therefore be of greater significance in lakes such as Blelham Tarn than in more eutrophic systems. PMID:4004224

  7. Effect of bioturbation on metal-sulfide oxidation in surficial freshwater sediments

    SciTech Connect

    Peterson, G.S.; Ankley, G.T.; Leonard, E.N.

    1996-12-01

    Recent studies have demonstrated the role of acid-volatile sulfide (AVS) in controlling the bioavailability of several cationic metals in anoxic sediments. However, metal-sulfide complexes can be relatively labile with respect to oxidation associated with factors such as seasonal changes in rates of oxidation/production of AVS. Another potentially important mechanism of AVS oxidation in surficial sediments is bioturbation. The authors used different densities of the burrowing oligochaete Lumbriculus variegatus in a series of laboratory experiments to evaluate the effect of bioturbation on oxidation of AVS and subsequent bioavailability of cadmium and zinc spiked into freshwater sediments. Metal bioavailability was determined directly by bioaccumulation in the test organisms and indirectly through analysis of interstitial (pore) water metal concentrations. In the studies, horizon-specific sediment analyses were conducted to assess spatial differences in AVS and pore-water metal concentrations specifically related to organism activity. Burrowing activity of the oligochaete significantly reduced AVS concentrations in surficial sediments in a density-dependent manner and resulted in elevated interstitial water concentrations of cadmium but not zinc. Concentrations of cadmium in pore water from deeper horizons were consistently lower than those in the surficial sediments. The bioaccumulation of cadmium, but not zinc, but the oligochaetes. Overall, the results indicate that bioturbation can enhance the bioavailability of some cationic metals in surficial sediments, via oxidation of AVS, and demonstrate the importance of analyzing surficial sediments when assessing bioavailability of metals in sediments.

  8. Stratification of Archaea in the Deep Sediments of a Freshwater Meromictic Lake: Vertical Shift from Methanogenic to Uncultured Archaeal Lineages

    PubMed Central

    Borrel, Guillaume; Lehours, Anne-Catherine; Crouzet, Olivier; Jézéquel, Didier; Rockne, Karl; Kulczak, Amélie; Duffaud, Emilie; Joblin, Keith; Fonty, Gérard

    2012-01-01

    As for lineages of known methanogens, several lineages of uncultured archaea were recurrently retrieved in freshwater sediments. However, knowledge is missing about how these lineages might be affected and structured according to depth. In the present study, the vertical changes of archaeal communities were characterized in the deep sediment of the freshwater meromictic Lake Pavin. For that purpose, an integrated molecular approach was performed to gain information on the structure, composition, abundance and vertical stratification of archaeal communities thriving in anoxic freshwater sediments along a gradient of sediments encompassing 130 years of sedimentation. Huge changes occurred in the structure and composition of archaeal assemblages along the sediment core. Methanogenic taxa (i.e. Methanosaeta and Methanomicrobiales) were progressively replaced by uncultured archaeal lineages (i.e. Marine Benthic Group-D (MBG-D) and Miscellaneous Crenarchaeal Group (MCG)) which are suspected to be involved in the methane cycle. PMID:22927959

  9. 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...

  10. Development and application of freshwater sediment-toxicity benchmarks for currently used pesticides.

    PubMed

    Nowell, Lisa H; Norman, Julia E; Ingersoll, Christopher G; Moran, Patrick W

    2016-04-15

    Sediment-toxicity benchmarks are needed to interpret the biological significance of currently used pesticides detected in whole sediments. Two types of freshwater sediment benchmarks for pesticides were developed using spiked-sediment bioassay (SSB) data from the literature. These benchmarks can be used to interpret sediment-toxicity data or to assess the potential toxicity of pesticides in whole sediment. The Likely Effect Benchmark (LEB) defines a pesticide concentration in whole sediment above which there is a high probability of adverse effects on benthic invertebrates, and the Threshold Effect Benchmark (TEB) defines a concentration below which adverse effects are unlikely. For compounds without available SSBs, benchmarks were estimated using equilibrium partitioning (EqP). When a sediment sample contains a pesticide mixture, benchmark quotients can be summed for all detected pesticides to produce an indicator of potential toxicity for that mixture. Benchmarks were developed for 48 pesticide compounds using SSB data and 81 compounds using the EqP approach. In an example application, data for pesticides measured in sediment from 197 streams across the United States were evaluated using these benchmarks, and compared to measured toxicity from whole-sediment toxicity tests conducted with the amphipod Hyalella azteca (28-d exposures) and the midge Chironomus dilutus (10-d exposures). Amphipod survival, weight, and biomass were significantly and inversely related to summed benchmark quotients, whereas midge survival, weight, and biomass showed no relationship to benchmarks. Samples with LEB exceedances were rare (n=3), but all were toxic to amphipods (i.e., significantly different from control). Significant toxicity to amphipods was observed for 72% of samples exceeding one or more TEBs, compared to 18% of samples below all TEBs. Factors affecting toxicity below TEBs may include the presence of contaminants other than pesticides, physical/chemical characteristics

  11. Development and application of freshwater sediment-toxicity benchmarks for currently used pesticides.

    PubMed

    Nowell, Lisa H; Norman, Julia E; Ingersoll, Christopher G; Moran, Patrick W

    2016-04-15

    Sediment-toxicity benchmarks are needed to interpret the biological significance of currently used pesticides detected in whole sediments. Two types of freshwater sediment benchmarks for pesticides were developed using spiked-sediment bioassay (SSB) data from the literature. These benchmarks can be used to interpret sediment-toxicity data or to assess the potential toxicity of pesticides in whole sediment. The Likely Effect Benchmark (LEB) defines a pesticide concentration in whole sediment above which there is a high probability of adverse effects on benthic invertebrates, and the Threshold Effect Benchmark (TEB) defines a concentration below which adverse effects are unlikely. For compounds without available SSBs, benchmarks were estimated using equilibrium partitioning (EqP). When a sediment sample contains a pesticide mixture, benchmark quotients can be summed for all detected pesticides to produce an indicator of potential toxicity for that mixture. Benchmarks were developed for 48 pesticide compounds using SSB data and 81 compounds using the EqP approach. In an example application, data for pesticides measured in sediment from 197 streams across the United States were evaluated using these benchmarks, and compared to measured toxicity from whole-sediment toxicity tests conducted with the amphipod Hyalella azteca (28-d exposures) and the midge Chironomus dilutus (10-d exposures). Amphipod survival, weight, and biomass were significantly and inversely related to summed benchmark quotients, whereas midge survival, weight, and biomass showed no relationship to benchmarks. Samples with LEB exceedances were rare (n=3), but all were toxic to amphipods (i.e., significantly different from control). Significant toxicity to amphipods was observed for 72% of samples exceeding one or more TEBs, compared to 18% of samples below all TEBs. Factors affecting toxicity below TEBs may include the presence of contaminants other than pesticides, physical/chemical characteristics

  12. Development and application of freshwater sediment-toxicity benchmarks for currently used pesticides

    USGS Publications Warehouse

    Nowell, Lisa H.; Norman, Julia E.; Ingersoll, Christopher G.; Moran, Patrick W.

    2016-01-01

    Sediment-toxicity benchmarks are needed to interpret the biological significance of currently used pesticides detected in whole sediments. Two types of freshwater sediment benchmarks for pesticides were developed using spiked-sediment bioassay (SSB) data from the literature. These benchmarks can be used to interpret sediment-toxicity data or to assess the potential toxicity of pesticides in whole sediment. The Likely Effect Benchmark (LEB) defines a pesticide concentration in whole sediment above which there is a high probability of adverse effects on benthic invertebrates, and the Threshold Effect Benchmark (TEB) defines a concentration below which adverse effects are unlikely. For compounds without available SSBs, benchmarks were estimated using equilibrium partitioning (EqP). When a sediment sample contains a pesticide mixture, benchmark quotients can be summed for all detected pesticides to produce an indicator of potential toxicity for that mixture. Benchmarks were developed for 48 pesticide compounds using SSB data and 81 compounds using the EqP approach. In an example application, data for pesticides measured in sediment from 197 streams across the United States were evaluated using these benchmarks, and compared to measured toxicity from whole-sediment toxicity tests conducted with the amphipod Hyalella azteca (28-d exposures) and the midge Chironomus dilutus (10-d exposures). Amphipod survival, weight, and biomass were significantly and inversely related to summed benchmark quotients, whereas midge survival, weight, and biomass showed no relationship to benchmarks. Samples with LEB exceedances were rare (n = 3), but all were toxic to amphipods (i.e., significantly different from control). Significant toxicity to amphipods was observed for 72% of samples exceeding one or more TEBs, compared to 18% of samples below all TEBs. Factors affecting toxicity below TEBs may include the presence of contaminants other than pesticides, physical

  13. Spatiotemporal variation of planktonic and sediment bacterial assemblages in two plateau freshwater lakes at different trophic status.

    PubMed

    Dai, Yu; Yang, Yuyin; Wu, Zhen; Feng, Qiuyuan; Xie, Shuguang; Liu, Yong

    2016-05-01

    Both planktonic and sediment bacterial assemblages are the important components of freshwater lake ecosystems. However, their spatiotemporal shift and the driving forces remain still elusive. Eutrotrophic Dianchi Lake and mesotrophic Erhai Lake are the largest two freshwater lakes on the Yunnan Plateau (southwestern China). The present study investigated the spatiotemporal shift in both planktonic and sediment bacterial populations in these two plateau freshwater lakes at different trophic status. For either lake, both water and sediment samples were collected from six sampling locations in spring and summer. Bacterioplankton community abundance in Dianchi Lake generally far outnumbered that in Erhai Lake. Sediment bacterial communities in Erhai Lake were found to have higher richness and diversity than those in Dianchi Lake. Sediments had higher bacterial community richness and diversity than waters. The change patterns for both planktonic and sediment bacterial communities were lake-specific and season-specific. Either planktonic or sediment bacterial community structure showed a distinct difference between in Dianchi Lake and in Erhai Lake, and an evident structure difference was also found between planktonic and sediment bacterial communities in either of these two lakes. Planktonic bacterial communities in both Dianchi Lake and Erhai Lake mainly included Proteobacteria (mainly Alpha-, Beta-, and Gammaproteobacteria), Bacteroidetes, Actinobacteria, Cyanobacteria, and Firmicutes, while sediment bacterial communities were mainly represented by Proteobacteria (mainly Beta- and Deltaproteobacteria), Bacteroidetes, Chlorobi, Nitrospirae, Acidobacteria, and Chloroflexi. Trophic status could play important roles in shaping both planktonic and sediment bacterial communities in freshwater lakes.

  14. Vegetation Influences on Tidal Freshwater Marsh Sedimentation and Accretion

    NASA Astrophysics Data System (ADS)

    Cadol, D. D.; Elmore, A. J.; Engelhardt, K.; Palinkas, C. M.

    2011-12-01

    Continued sea level rise, and the potential for acceleration over the next century, threatens low-lying natural and cultural resources throughout the world. In the national capital region of the United States, for example, the National Park Service manages over 50 km^2 of land along the shores of the tidal Potomac River and its tributaries that may be affected by sea level rise. Dyke Marsh Wildlife Preserve on the Potomac River south of Washington, DC, is one such resource with a rich history of scientific investigation. It is a candidate for restoration to replace marsh area lost to dredging in the 1960s, yet for restoration to succeed in the long term, accretion must maintain the marsh surface within the tidal range of rising relative sea level. Marsh surface accretion rates tend to increase with depth in the tidal frame until a threshold depth is reached below which marsh vegetation cannot be sustained. Suspended sediment concentration, salinity, tidal range, and vegetation community all influence the relationship between depth and accretion rate. The complex interactions among these factors make sedimentation rates difficult to generalize across sites. Surface elevation tables (SET) and feldspar marker horizons have been monitored at 9 locations in Dyke Marsh for 5 years, providing detailed data on sedimentation, subsidence, and net accretion rates at these locations. We combine these data with spatially rich vegetation surveys, a LiDAR derived 1-m digital elevation model of the marsh, and temperature-derived inundation durations to model accretion rates across the marsh. Temperature loggers suggest a delayed arrival of tidal water within the marsh relative to that predicted by elevation alone, likely due to hydraulic resistance caused by vegetation. Wave driven coastal erosion has contributed to bank retreat rates of ~2.5 m/yr along the Potomac River side of the marsh while depositing a small berm of material inland of the retreating shoreline. Excluding sites

  15. Distinguishing internal and external sediment sources in a tidal freshwater wetland, the Netherlands

    NASA Astrophysics Data System (ADS)

    van der Deijl, Eveline C.; van der Perk, Marcel; Kik, Nanda J.; Verschelling, Eelco; Middelkoop, Hans

    2015-04-01

    Many deltas across the globe suffer from drowning due to sea level rise or land subsidence in combination with sediment starvation. The process of drowning can be attenuated by enhancing sediment inputs or the sediment trapping efficiency of deltas. To examine the sediment budget of delta areas based on measurements of sediment deposition, it is essential to distinguish the sediment that has entered the area from upstream areas from sediment that has been redistributed within the area. This pilot study aims to explore the prospects to distinguish between external and internal sediment sources based on the geochemical composition of the sediment deposited. This study was carried out in the Kleine Noordwaard, which is part of the Brabantse Biesbosch, a former inland delta located in-between the Rhine and Meuse rivers in the south-western part of the Netherlands. A significant part of this area has been embanked and turned into polder areas in the early 19th century. In contrast to many tidal creeks and flats, the polder areas have not received inputs of severely contaminated river sediment between the 1930s and 1980s. A number of polders have recently or are currently being de-poldered again, i.e. converted from agricultural polder land into an inundated tidal freshwater wetland, in order to increase the conveyance capacity of the Rhine River during extreme discharge situations, thereby lowering the peak water levels upstream and to enhance the nature values of the area. The external and internal sediment sources of the sediment deposited in the Kleine Noordwaard could be discriminated based on the zinc (Zn) and rubidium (Rb) concentrations. These two elements exhibit a different linear relation for the more contaminated external sediment originating from the Rhine River and the less contaminated, internally redistributed sediment originating from the topsoil of the former polder area. The mixture proportion for each sediment sample could not be directly derived

  16. Different methods for extracting bacteria from freshwater sediment and a simple method to measure bacterial production in sediment samples.

    PubMed

    dos Santos Furtado, A L; Casper, P

    2000-08-01

    The efficiency of different treatments was tested to extract bacterial cells from freshwater sediment samples. The influence of sonication, density gradient centrifugation, fixation by formalin and centrifugation speed on bacterial recovery was investigated. The method developed by Smith and Azam [Mar. Microb. Food Webs 6 (1992) 107] to measure microbial activity on bacterioplankton (3H-leucine incorporation), was also evaluated in sediment samples. After 1 min of sonication bacterial abundance was reduced by about 47% in diluted sediments with tetrasodium pyrophosphate. With the addition of Percoll after sonication, bacterial counts were not significantly different (P<0.05). Fixation by formalin increased bacterial counts using sonication. However, higher bacterial abundance was estimated in non-sonicated samples. Bacterial abundance in samples centrifuged at 7000xg with and without Percoll was not significantly different (P<0.05). Highest bacterial abundance was obtained after centrifugation at low speed (750xg). Bacterial abundance decreased with higher centrifugation speed (750, 1500 and 3000xg), the difference, however, was not significant. Bacterial production ranged from 0.10 microg C cm(-3) d(-1) in autoclaved sediment to 0. 27 microg C cm(-3) d(-1) in untreated sediment. The radioactivity measured in controls of both untreated and autoclaved sediment was high (70 and 91%, respectively), indicating a high level of leucine adsorption in sediment particles. In contrast, radioactivity in control samples previously centrifuged was markedly lower (6%). Despite the high values of radioactivity in the controls, bacterial production in untreated sediment was significantly higher than in centrifuged sediment (P<0.05).

  17. Toxicity of nickel-spiked freshwater sediments to benthic invertebrates-Spiking methodology, species sensitivity, and nickel bioavailability

    USGS Publications Warehouse

    Besser, John M.; Brumbaugh, William G.; Kemble, Nile E.; Ivey, Chris D.; Kunz, James L.; Ingersoll, Christopher G.; Rudel, David

    2011-01-01

    This report summarizes data from studies of the toxicity and bioavailability of nickel in nickel-spiked freshwater sediments. The goal of these studies was to generate toxicity and chemistry data to support development of broadly applicable sediment quality guidelines for nickel. The studies were conducted as three tasks, which are presented here as three chapters: Task 1, Development of methods for preparation and toxicity testing of nickel-spiked freshwater sediments; Task 2, Sensitivity of benthic invertebrates to toxicity of nickel-spiked freshwater sediments; and Task 3, Effect of sediment characteristics on nickel bioavailability. Appendices with additional methodological details and raw chemistry and toxicity data for the three tasks are available online at http://pubs.usgs.gov/sir/2011/5225/downloads/.

  18. Scale and Seasonal Controls on Nitrate and Sediment Retention in Freshwater Tidal Wetlands

    NASA Astrophysics Data System (ADS)

    Prestegaard, K. L.; Seldomridge, E.; Statkiewicz, A.

    2013-12-01

    Channel networks in freshwater tidal wetlands convey water, sediment, and solutes into marsh interiors where sediment deposition and biogeochemical processes, such as denitrification and nitrogen uptake occur. Tidal inlets that connect these channel network systems to the main estuary define the initial solute or sediment load into these systems, but channel, soil, and vegetation characteristics influence nitrate and sediment retention. We used field measurements and remotely sensed images to determine marsh area, stream length, inlet morphology, and channel morphology for the 267 marshes in the freshwater tidal ecosystem. Discharge and water volume over high tidal cycles was measured at selected inlets representative of the range of inlet sizes in the ecosystem. Aquatic vegetation distribution and density was also measured at these inlets. These data were used to develop geomorphic-hydraulic relationships for the marshes for winter (no vegetation) and summer (vegetated) conditions. Nitrate and sediment retention were determined from field mass balance measurements based on water flux and concentration measurements taken over tidal cycle at inlets to selected marshes of varying size over a 3-year period. These mass balance data indicate that net nitrate retention is a simple function of tidal water volume for marshes of different sizes and for various vegetated conditions. These data suggest that nitrate retention is transport limited for the range of initial nitrate concentrations observed in this system. Although nitrate retention was a function of tidal water volume, it was also seasonally variable due to restrictions in water flow and volume caused by aquatic vegetation in summer months. Sediment retention is seasonally variable due to the strong controls exerted by emergent and submerged aquatic vegetation and decoupled from the water volume dependence observed for nitrate retention. Variations in sediment retention caused by vegetation resulted in channel

  19. Biotransformation of tetrabromobisphenol A (TBBPA) in anaerobic digester sludge, soils, and freshwater sediments.

    PubMed

    McAvoy, Drew C; Pittinger, Charles A; Willis, Alison M

    2016-09-01

    The biotransformation of tetrabromobisphenol A (TBBPA) was evaluated in anaerobic digester sludge, soils, and freshwater sediments. In anaerobic digester sludge, TBBPA biotransformed rapidly with a 50% disappearance time (DT50) of 19 days, though little mineralization (1.1%) was observed. In aerobic soils, mineralization of TBBPA ranged from 17.5% to 21.6% with 55.3-83.6% of the TBBPA incorporated into the soils as a non-extractable bound residue. The DT50 for TBBPA in aerobic soils ranged from 5.3 to 7.7 days. In anaerobic soils, 48.3-100% of the TBBPA was incorporated into the soils as non-extractable bound residue with <4% mineralized. The soil fate studies demonstrated extensive incorporation of TBBPA into the solid matrix and this association was related to the amount of organic carbon in the soils (i.e., greater association of TBBPA with soil at higher organic carbon content). In anaerobic sediments the DT50 for TBBPA ranged from 28 to 42 days, whereas in aerobic sediments the DT50 for TBBPA ranged from 48 to 84 days and depended on the initial dose concentration. Most of the TBBPA in the sediment studies was incorporated as a non-extractable bound residue with little mineralization observed. Sediment extracts revealed three unknown biotransformation products and bisphenol A (BPA). These results were consistent with previously published studies where TBBPA biotransformed in anaerobic environments (digester sludge and sediments) by debromination and slowly mineralized in the test environments (anaerobic digester sludge, soils, and freshwater sediments).

  20. 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.

  1. The palaeoecologic and biostratigraphic evaluation of Middle Miocene freshwater sediments and microfossils near Denkendorf (Bavaria)

    NASA Astrophysics Data System (ADS)

    Pirkenseer, C.; Reichenbacher, B.

    2009-04-01

    Isolated freshwater sediments that partially cover the Jurassic limestones of the Swabian and Franconian Alb represent the northernmost expansion of the Molasse sediments. These sediments represent the analogue to the Brackish Molasse and part of the Upper Freshwater Molasse (Ottnangian to Badenian). Samples of six drillcores from the vicinity of Denkendorf (Franconian Alb, Bavaria) yielded ostracods of the superfamily Cypridoidea, frequent oogonia of charophytes, otoliths of the family Gobiidae, teeth of several taxa of micromammals as well as abundant material of amphibians, reptiles and gastropods. The sediments show a general trend from basal, more clastic influenced deposits to uniformly developed marly sediments with freshwater carbonate intercalations. The acme of microfossil occurrences is associated with the latter section. The palaeoecologic analysis characterises the environment as structured littoral zone (e.g. Pseudocandona steinheimensis, Gyraulus sp., Planorbarius sp., Rana ridibunda, Triturus sp.) of a larger oligo- to mesotrophic (Chara spp., Nitellopsis spp.) low-energy freshwater system under a warm subtropical to tropical climate (Diplocynodon cf. D. styriacus, Channa sp.). The cooccurrence of suboxia- and oligotrophy-tolerant species like Palaeocarassius sp. and Channa sp. may indicate short intervals of regional depletion of oxygene and raise of nutrient content. Mediocypris candonaeformis and Gobius latiformis represent relict species of the preceding Brackwassermolasse. Terrestrial elements include Proboscidea (phalanx), Cervidae (astragalus), land turtles (Testudo sp.) and gastropods (Clausiliidae, Pupillidae, Cepaea sp.). The occurrence of Jurassic xenoclasts and bean iron ore indicate the presence of a tributary system. The faunal and floral assemblages show close affinities to other localities of the Molasse Basin (e.g., Sandelzhausen). In accordance with the depositional history this indicates a palaeogeographic connection with the

  2. Role of methanogens and other bacteria in degradation of dimethyl sulfide and methanethiol in anoxic freshwater sediments

    SciTech Connect

    Lomans, B.P.; Op den Camp, H.J.M.; Pol, A.; Drift, C. van der; Vogels, G.D.

    1999-05-01

    The roles of several trophic groups of organisms (methanogens and sulfate- and nitrate-reducing bacteria) in the microbial degradation of methanethiol (MT) and dimethyl sulfide (DMS) were studied in freshwater sediments. The incubation of DMS- and MT-amended slurries revealed that methanogens are the dominant DMS and MT utilizers in sulfate-poor freshwater systems. In sediment slurries, which were depleted of sulfate, 75 {micro}mol of DMS was stoichiometrically converted into 112 {micro}mol of methane. The addition of methanol or MT to DMS-degrading slurries at concentrations similar to that of DMS reduced DMS degradation rates. This indicates that the methanogens in freshwater sediments, which degrade DMS, are also consumers of methanol and MT. To verify whether a competition between sulfate-reducing and methanogenic bacteria for DMS or MT takes place in sulfate-rich freshwater systems, the effects of sulfate and inhibitors, like bromoethanesulfonic acid, molybdate, and tungstate, on the degradation of MT and DMS were studied. The results for these sulfate-rich and sulfate-amended slurry incubations clearly demonstrated that besides methanogens, sulfate-reducing bacteria take part in MT and DMS degradation in freshwater sediments, provided that sulfate is available. The possible involvement of an interspecies hydrogen transfer in these processes is discussed. In general, the study provides evidence for methanogenesis as a major sink for MT and DMS in freshwater sediments.

  3. Impact of a large tropical reservoir on riverine transport of sediment, carbon, and nutrients to downstream wetlands

    NASA Astrophysics Data System (ADS)

    Kunz, Manuel J.; Wüest, Alfred; Wehrli, Bernhard; Landert, Jan; Senn, David B.

    2011-12-01

    Large dams can have major ecological and biogeochemical impacts on downstream ecosystems such as wetlands and riparian habitats. We examined sediment removal and carbon (C), nitrogen (N), and phosphorus (P) cycling in Itezhi-Tezhi Reservoir (ITT; area = 364 km2, hydraulic residence time = 0.7 yr), which is located directly upstream of a high ecological value floodplain ecosystem (Kafue Flats) in the Zambezi River Basin. Field investigations (sediment cores, sediment traps, water column samples), mass balance estimates, and a numerical biogeochemical reservoir model were combined to estimate N, P, C, and sediment removal, organic C mineralization, primary production, and N fixation. Since dam completion in 1978, 330 × 103 tons (t) of sediment and 16 × 103, 1.5 × 103, 200 t of C, N, and P, respectively, have accumulated annually in ITT sediments. Approximately 50% of N inputs and 60% of P inputs are removed by the reservoir, illustrating its potential in decreasing nutrients to the downstream Kafue Flats floodplain. The biogeochemical model predicted substantial primary production in ITT (˜280 g C m-2 yr-1), and significant N-fixation (˜30% for the total primary production) was required to support primary production due to marginal inputs of inorganic N. Model simulations indicate that future hydropower development in the reservoir, involving the installation of turbines driven by hypolimnetic water, will likely result in the delivery of low-oxygen waters to downstream ecosystems and increased outputs of dissolved inorganic N and P by a factor of ˜4 and ˜2 compared to current dam management, respectively.

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

    PubMed

    Fetters, Kyle J; Costello, David M; Hammerschmidt, Chad R; Burton, G Allen

    2016-03-01

    Sediments in navigation-dominated waterways frequently are contaminated with a variety of particle-associated pollutants and are subject to frequent short-term resuspension events. There is little information documenting whether resuspension of metal-contaminated sediments has adverse ecological effects on resident aquatic organisms. Using a novel laboratory approach, the authors examined the mobilization of Zn, Cu, Cd, Pb, Ni, and Cr during resuspension of 1 freshwater and 2 coastal marine sediments and whether resuspension and redeposition resulted in toxicity to model organisms. Sediment flux exposure chambers were used to resuspend metal-contaminated sediments from 1 site in Lake DePue, Illinois (USA), and 2 sites in Portsmouth Naval Shipyard, Maine (USA). Short-term (4-h) resuspension of sediment at environmentally relevant suspended particulate matter concentrations (<1 g/L) resulted in metal mobilization to water that was sediment and metal specific. Overall, the net release of metals from suspended particles was limited, likely because of scavenging by organic matter and Fe oxides that formed during sediment interaction with oxic water. Minimal toxicity to organisms (survival of Hyalella azteca and Daphnia magna; survival, growth, and tissue metal concentration of Neanthes arenaceodentata; bioluminescence of Pyrocystis lunula) was observed during 4-h exposure to resuspended sediments and during 4-d to 10-d post-exposure recovery periods in uncontaminated water. Redeposited suspended particles exhibited increased metal bioavailability and toxicity to H. azteca, highlighting the potential for adverse ecological impacts because of changes in metal speciation. It is important to consider interactions between organisms' life histories and sediment disturbance regimes when assessing risks to ecosystems.

  5. Molecular diversity and tools for deciphering the methanogen community structure and diversity in freshwater sediments.

    PubMed

    Chaudhary, Prem Prashant; Brablcová, Lenka; Buriánková, Iva; Rulík, Martin

    2013-09-01

    Methanogenic archaeal communities existing in freshwater sediments are responsible for approximately 50 % of the total global emission of methane. This process contributes significantly to global warming and, hence, necessitates interventional control measures to limit its emission. Unfortunately, the diversity and functional interactions of methanogenic populations occurring in these habitats are yet to be fully characterized. Considering several disadvantages of conventional culture-based methodologies, in recent years, impetus is given to molecular biology approaches to determine the community structure of freshwater sedimentary methanogenic archaea. 16S rRNA and methyl coenzyme M reductase (mcrA) gene-based cloning techniques are the first choice for this purpose. In addition, electrophoresis-based (denaturing gradient gel electrophoresis, temperature gradient gel electrophoresis, and terminal restriction fragment length polymorphism) and quantitative real-time polymerase chain reaction techniques have also found extensive applications. These techniques are highly sensitive, rapid, and reliable as compared to traditional culture-dependent approaches. Molecular diversity studies revealed the dominance of the orders Methanomicrobiales and Methanosarcinales of methanogens in freshwater sediments. The present review discusses in detail the status of the diversity of methanogens and the molecular approaches applied in this area of research.

  6. Molecular diversity and tools for deciphering the methanogen community structure and diversity in freshwater sediments.

    PubMed

    Chaudhary, Prem Prashant; Brablcová, Lenka; Buriánková, Iva; Rulík, Martin

    2013-09-01

    Methanogenic archaeal communities existing in freshwater sediments are responsible for approximately 50 % of the total global emission of methane. This process contributes significantly to global warming and, hence, necessitates interventional control measures to limit its emission. Unfortunately, the diversity and functional interactions of methanogenic populations occurring in these habitats are yet to be fully characterized. Considering several disadvantages of conventional culture-based methodologies, in recent years, impetus is given to molecular biology approaches to determine the community structure of freshwater sedimentary methanogenic archaea. 16S rRNA and methyl coenzyme M reductase (mcrA) gene-based cloning techniques are the first choice for this purpose. In addition, electrophoresis-based (denaturing gradient gel electrophoresis, temperature gradient gel electrophoresis, and terminal restriction fragment length polymorphism) and quantitative real-time polymerase chain reaction techniques have also found extensive applications. These techniques are highly sensitive, rapid, and reliable as compared to traditional culture-dependent approaches. Molecular diversity studies revealed the dominance of the orders Methanomicrobiales and Methanosarcinales of methanogens in freshwater sediments. The present review discusses in detail the status of the diversity of methanogens and the molecular approaches applied in this area of research. PMID:23877581

  7. Suspended-sediment loads, reservoir sediment trap efficiency, and upstream and downstream channel stability for Kanopolis and Tuttle Creek Lakes, Kansas, 2008-10

    USGS Publications Warehouse

    Juracek, Kyle E.

    2011-01-01

    Continuous streamflow and turbidity data collected from October 1, 2008, to September 30, 2010, at streamgage sites upstream and downstream from Kanopolis and Tuttle Creek Lakes, Kansas, were used to compute the total suspended-sediment load delivered to and released from each reservoir as well as the sediment trap efficiency for each reservoir. Ongoing sedimentation is decreasing the ability of the reservoirs to serve several purposes including flood control, water supply, and recreation. River channel stability upstream and downstream from the reservoirs was assessed using historical streamgage information. For Kanopolis Lake, the total 2-year inflow suspended-sediment load was computed to be 600 million pounds. Most of the suspended-sediment load was delivered during short-term, high-discharge periods. The total 2-year outflow suspended-sediment load was computed to be 31 million pounds. Sediment trap efficiency for the reservoir was estimated to be 95 percent. The mean annual suspended-sediment yield from the upstream basin was estimated to be 129,000 pounds per square mile per year. No pronounced changes in channel width were evident at five streamgage sites located upstream from the reservoir. At the Ellsworth streamgage site, located upstream from the reservoir, long-term channel-bed aggradation was followed by a period of stability. Current (2010) conditions at five streamgages located upstream from the reservoir were typified by channel-bed stability. At the Langley streamgage site, located immediately downstream from the reservoir, the channel bed degraded 6.15 feet from 1948 to 2010. For Tuttle Creek Lake, the total 2-year inflow suspended-sediment load was computed to be 13.3 billion pounds. Most of the suspended-sediment load was delivered during short-term, high-discharge periods. The total 2-year outflow suspended-sediment load was computed to be 327 million pounds. Sediment trap efficiency for the reservoir was estimated to be 98 percent. The mean

  8. Evaluating the provenance of fine sediment in degraded Freshwater Pearl Mussel habitats.

    NASA Astrophysics Data System (ADS)

    Blake, Will; Haley, Steve; Goddard, Rupert; Stone, Peter; Broadhead, Kat

    2015-04-01

    Freshwater Pearl Mussels (FWPM), Margaritifera margaritifera, are among the most critically threatened freshwater bivalves worldwide. In addition to their important roles in particle processing, nutrient release, and sediment mixing, they also serve as an ideal target species for evaluation of aquatic ecosystem functioning especially in the context of their symbiotic relationship with Atlantic salmon Salmo salar and brown or sea trout Salmo trutta. Poor water quality, particularly eutrophication, and siltation are considered major contributory factors in the decline of the species hence management of diffuse water pollution from agriculture (DWPA) is a key priority in catchments that host FWPM habitats. Against this background, this study adopted a combined monitoring, surveying and sediment fingerprinting approach to determine the principal sources of fine sediment impacting FWPM habitats in the River Clun, a Special area of Conservation (SAC) for FWPMs in central western UK. Potential sediment production hotspot areas in the ca 200 km2 catchment area upstream of FWPM habitats were initially evaluated using the SCIMAP risk mapping tool. Suspended sediment monitoring was undertaken on the main stem channel where FWPM habitats are located and wet weather catchment walkover surveys undertaken along the upstream river and stream network. Within this monitoring framework, sediment fingerprinting was undertaken at two levels. The first level aimed to link primary catchment sources (cultivated and uncultivated soil, channel bank erosion, and material transported via roads and tracks) to suspended sediment output from each main tributary upstream of the FWPM beds. The second level linked silt in the FWMP beds to the main tributaries, as integrated source end-members, with the inclusion of main channel bank erosion, a notable feature of walkover surveys as an additional source. Geochemical fingerprints, determined by XRF spectroscopy, were dominated by conservative mineral

  9. Factors controlling the sediment trapping efficiency of a freshwater tidal wetland

    NASA Astrophysics Data System (ADS)

    van der Deijl, Eveline C.; Verschelling, Eelco; van der Perk, Marcel; Middelkoop, Hans

    2016-04-01

    Many freshwater tidal wetlands suffer from drowning due to sea level rise, increased river discharge or land subsidence in combination with sediment starvation. This drowning may be attenuated by enhancing the sediment input into a wetland or the sediment trapping efficiency within a wetland. The objective of this study is to identify this trapping efficiency (defined as the proportion of the incoming sediment that is deposited or trapped in the area) and the controlling factors for a recently re-opened freshwater tidal wetland polder in the Biesbosch inland delta in the southwest of the Netherlands. The wetland receives water and sediment from the Nieuwe Merwede River, a distributary of the Rhine River in the Netherlands. Water and sediment budgets were established for several events between July 2014 and March 2015, including a river discharge event, windstorm events, and different tidal ranges. Water levels, discharges and suspended sediment concentrations were measured automatically at the in- and outlet of the area at an interval of 10 minutes. The discharge was measured using Horizontal Acoustic Doppler Profilers calibrated using Vertical Acoustic Doppler Profiler measurements during regular field visits. The suspended sediment concentrations were measured using turbidity meters which were calibrated using water samples collected during the field campaigns. The area is mainly functioning as a side channel with a small storage capacity. The water balance of the area is primary influenced by the tidal water level variation at the in- and outlet points of the area. The tidal water level variation has a larger impact when the river discharge is low, while wind strength and direction further enhance or reduce the water flow through the area. The former polder area receives on average 48.8 ton per day, which corresponds to an average sediment trapping efficiency of 0.3. Although the amount of sediment trapped within the area increases at higher river discharge

  10. Effects of storage time on the toxicity of sediments to freshwater benthic invertebrates

    SciTech Connect

    DeFoe, D.L.; Ankley, G.T.

    1995-12-31

    The objective of this study was to define the effects of storage time on the toxicity of a series of freshwater sediments. Sixteen sediments with varying types of contaminants (metals, pesticides, PCBs, ammonia) were collected, held at 4 C, and periodically tested for toxicity to the amphipod Hyalella azteca and the midge Chironomus tentans for storage times ranging from 8.5 to 25 months. The sediments ranged from nontoxic to extremely toxic (100% mortality) in 10-d assays with both species, with the majority of samples displaying an intermediate degree of toxicity (e.g., partial kills, reduced growth). Toxicity of sediments causing total mortality of organisms in 10-d was quantified through the determination of LT50 (lethal time to 50% mortality) assays, in addition to the standard 10-d tests. Toxicity of nearly all the samples did not vary significantly with storage time; in those instances when toxicity did change, the same relative conclusions concerning sample toxicity generally would have been made regardless of when they were tested (e.g., toxic samples did not become non-toxic). This data suggests that current guidelines concerning sediment storage times (e.g., 0--8 weeks) may be overly restrictive, at least with respect to toxicity testing. The results also suggested that some test variability inherent in whole sediment assays can actually be reduced by short term storage. That is, among replicates, variability appeared to decrease with increasing storage time.

  11. Dual radiotracer measurement of zoobenthos-mediated solute and particle transport in freshwater sediments

    SciTech Connect

    Krezoski, J.R.; Robbins, J.A.; White, D.S.

    1984-09-01

    ..gamma.. spectroscopy methods have been applied to determine the effects of two freshwater benthic macroinvertebrates, on reworking of sediments and the transfer of solutes across the sediment-water interface. Natural lake sediments and overlying water were contained in temperature-regulated rectangular plastic cells. After addition of Stylodrilus (oligochaete worms) and Pontoporeia (crustacean amphipods) to these microcosms, the vertical distribution of Cs-137 (a tracer of particle transport) and Na-22 (a tracer of solute transport) were determined. In cells with Stylodrilus, the Cs-137 layer moved downward at a rate that decreased exponentially with time. In cells with Pontoporeia, Cs-137 activity was smeared downward in time owing to eddy diffusive mixing of sediments over a small range (1-2 cm). In cells without worms, the veneer of Cs active material remained at the interface while the penetration of Na-22 into sediments was consistent with diffusion in free solution with small corrections for sediment porosity and sorption. In cells with live Stylodrilus, penetration of Na-22 within the feeding zone was considerably more rapid. Advective transport arises from the incorporation of Na-22 into pore fluids moved downward as a result of conveyor-belt feeding. In cells with Pontoporeia, De is approximately twice that in control cells. In these cells, Na-22 profiles may be treated theoretically without advection. 47 references, 6 figures, 2 tables.

  12. Endpoints for sediment toxicity tests with the freshwater bivalve Sphaerium corneum

    SciTech Connect

    Looise, B.A.S.; Holwerda, D.A.; Foekema, E.M.

    1994-12-31

    Being a participant in the EU project `Sediment toxicity tests for poorly water soluble substances` the authors examined toxicological endpoints with the freshwater bivalve Sphaerium corneum. These included induction of two biotransformation enzymes, glutathione S-transferase and catalase, and survival time under anoxic stress. Animals were taken from the field and exposed to sediments spiked with contaminants or to contaminants in a water-only system. Also a field sediment from a contaminated area was included. Spiking substances were lindane, dieldrin, benzo[a]pyrene, and PCB. After 1--5 weeks of exposure to contaminated sediments or water, animals were examined for induction of the biotransformation enzymes glutathione S-transferase (GST) and catalase. GST activity in whole body soft tissue was measured spectrophotometrically by the amount of conjugate formed, using 1-chloro-2,4-dinitrobenzene as a substrate and glutathione as a co-substrate. Catalase activity was also measured spectrophotometrically by the transformation rate of the substrate, hydrogen peroxide. None of the treatments resulted in a significant increase of GST or catalase activities. After 2--5 weeks of exposure to contaminated sediment, the animals were transferred to individual 10-mL bottles. Results show significant decrease of survival times of animals exposed to contaminated sediments.

  13. Higher nitrate-reducer diversity in macrophyte-colonized compared to unvegetated freshwater sediment.

    PubMed

    Kofoed, Michael V W; Stief, Peter; Hauzmayer, Sandra; Schramm, Andreas; Herrmann, Martina

    2012-10-01

    Freshwater macrophytes stimulate rhizosphere-associated coupled nitrification-denitrification and are therefore likely to influence the community composition and abundance of rhizosphere-associated denitrifiers and nitrate reducers. Using the narG gene, which encodes the catalytic subunit of the membrane-bound nitrate reductase, as a molecular marker, the community composition and relative abundance of nitrate-reducing bacteria were compared in the rhizosphere of the freshwater macrophyte species Littorella uniflora and Myriophyllum alterniflorum to nitrate-reducing communities in unvegetated sediment. Microsensor analysis indicated a higher availability of oxygen in the rhizosphere compared to unvegetated sediment, with a stronger release of oxygen from the roots of L. uniflora compared to M. alterniflorum. Comparison of narG clone libraries between samples revealed a higher diversity of narG phylotypes in association with the macrophyte rhizospheres compared to unvegetated sediment. Quantitative PCR targeting narG- and 16S rRNA-encoding genes pointed to a selective enrichment of narG gene copies in the rhizosphere. The results suggested that the microenvironment of macrophyte rhizospheres, characterized by the release of oxygen and labile organic carbon from the root system, had a stimulating effect on the diversity and relative abundance of rhizosphere-associated nitrate reducers. PMID:23041409

  14. Ultrasound-assisted extraction method for the simultaneous determination of emerging contaminants in freshwater sediments.

    PubMed

    de Sousa, Diana Nara Ribeiro; Grosseli, Guilherme Martins; Mozeto, Antonio Aparecido; Carneiro, Renato Lajarim; Fadini, Pedro Sergio

    2015-10-01

    Sediments are the fate of several emerging organic contaminants, such as pharmaceuticals, personal care products and hormones, and therefore an important subject in environmental monitoring studies. In the present work, a simple and sensitive method was developed, validated and applied for the simultaneous extraction of atenolol, caffeine, carbamazepine, diclofenac, ibuprofen, naproxen, propranolol, triclosan, estrone, 17-β-estradiol and 17-α-ethinylestradiol using ultrasound-assisted extraction from freshwater sediment samples followed by solid-phase extraction clean-up and liquid chromatography with tandem mass spectrometry detection. The solvent type and extraction pH were evaluated to obtain the highest recoveries of the compounds. The best method shows absolute recoveries between 54.0 and 94.4% at 50 ng/g concentration. The method exhibits good precision with relative standard deviation ranging from 1.0-16%. The detection and quantification limits ranged from 0.006-0.067 and 0.016-0.336 ng/g, respectively. The developed method was successfully applied to freshwater sediment samples collected from different sites in Jundiaí River basin of São Paulo State, Brazil. The compounds atenolol, caffeine, propranolol and triclosan were detected in all the sampling sites with concentrations of 13.8, 41.0, 28.5 and 176 ng/g, respectively. PMID:26257164

  15. Estimating of suspended sediment loads of rivers in the Seine downstream basin and coastal rivers in Southeastern Channel

    NASA Astrophysics Data System (ADS)

    Landemaine, Valentin; Cerdan, Olivier; Laignel, Benoit; Fournier, Matthieu; Copard, Yoann

    2014-05-01

    Sediment exports in rivers constitute the essential of materials transfer from the land surface to the ocean and contribute significantly to the transfer of nutrients, pesticides, heavy metals which can affect water quality. Such problems of water pollution are particularly present at the Norman loess plateaus because soil erosion is a frequent phenomena and mudslides are common. In this context, the quantification of sediment load, as well as the short and long term variability analysis are a key component for any sustainable management project of water resources. The quantification of sediment fluxes is based on turbidity, suspended sediment concentrations (SSC) and discharge measurements. These measurements must be made with sufficient high frequency for integrating temporal variability of SSC and flows. However, the cost of a high frequency monitoring limits their use at large scale. In France, discharges are monitored using daily frequency (Banque Hydro), while SSC are measured in monthly or bimonthly frequency under the national water quality survey system (RNB). With these low frequency measurements, an algorithm must be used to reconstruct SSC temporal variability and to estimate a sediment flux. Many estimation algorithms have been developed in recent decades, from the simplest to the most elaborate, but no consensus has been reached on the use of a particular algorithm because of the complexity of SSC-discharge relationship. In this study, the analysis focuses on eight Channel coastal watersheds and nine Seine watersheds in the downstream part. We have a several years of high-frequency measurements on nine watersheds with highly variable area (10 km² to 10,000 km²) and low-frequency measurements for all watersheds. From these data, we compared the statistical performance of eleven algorithms to estimate sediment fluxes conventionally used in the literature. These algorithms are: averaging estimator, ratio estimator, linear interpolation, rating curve

  16. Downstream Patterns of Bed-material Grain Size in a Large, Lowland Alluvial River Subject to low Sediment Supply

    NASA Astrophysics Data System (ADS)

    Singer, M. B.

    2007-12-01

    Downstream patterns of bed-material grain size were investigated over ~380 km of the Sacramento River in northern California, USA. Representative subaqueous bed-material samples were collected from ~125 cross sections spaced ~2 km apart using the 8.2 liter Ponar dredge sampler (for fine beds) and the 23.2 liter Cooper Scooper drag bucket sampler (for mixed and coarse beds), both of which were deployed from a jet boat. Samples were extracted from crossing points in straight reaches that represent the integration of sediment transport through upstream bends. Single samples were collected at simple, narrow cross sections and up to three samples were collected at sections with variable cross-stream topography. Samples were aggregated for each cross section, dried, sieved through eleven phi-sized mesh sieves (0.063-128 mm), and weighed to compute grain size distributions. The largest grain in >95% of all aggregated samples made up <5% of the total sample dry weight, rendering them adequately representative. Sacramento River grain size data suggest departure from widely accepted notions of bed material sorting in rivers in three fundamental ways: 1) subaqueous grain size data differ systematically from nearby data collected from exposed bars; 2) the transition from gravel to sand is not abrupt, but instead extends for several hundred kilometers; and 3) tributaries tend to have a small impact on mainstem downstream grain size sorting. These findings either imply something unique about the Sacramento River dataset compared with prior published data or differences in data collection methods and both possibilities were investigated. The Sacramento River basin is subject to lower sediment supply compared with prior systematically surveyed basins. The impact of decreasing supply (associated with a declining glacial hangover and human impacts) is a decoupling between main channel sediment transport and bar deposition. Thus, in addition to the inherent processes of grain

  17. Effects of storage time on the toxicity of sediments to freshwater benthic invertebrates

    SciTech Connect

    DeFoe, D.L.; Ankley, G.T.

    1994-12-31

    Current guidance concerning recommended storage times for sediments to be subjected to toxicity tests has been based largely on limited studies with a small number of samples. The objective of this study was to better define the effects of storage time on the toxicity of a series of freshwater sediments. Eighteen sediments with varying types of contaminants (metals, pesticides, PCBs, ammonia) were collected, held at 4 C, and periodically tested for toxicity to the amphipod Hyalella azteca and the midge Chironomus tentans for storage times ranging from 4 to 16 months. The sediments ranged from non-toxic to, extremely toxic (100% mortality) in 10-d assays with both species, with the majority of samples displaying an intermediate degree of toxicity. Toxicity of most of the samples did not vary significantly with storage time; in those instances when toxicity did change, the same relative conclusions concerning sample toxicity generally would have been made regardless of when they were tested. Their data suggest that current guidelines concerning sediment storage times may be overly restrictive, at least with respect toxicity testing.

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

    PubMed

    Laverman, Anniet M; Canavan, Richard W; Slomp, Caroline P; Cappellen, Philippe Van

    2007-07-01

    Nitrogen transformations and their response to salinization were studied in bottom sediment of a coastal freshwater lake (Haringvliet Lake, The Netherlands). The lake was formed as the result of a river impoundment along the south-western coast of the Netherlands, and is currently targeted for restoration of estuarine conditions. Nitrate porewater profiles indicate complete removal of NO(3)(-) within the upper few millimeters of sediment. Rapid NO(3)(-) consumption is consistent with the high potential rates of nitrate reduction (up to 200 nmol N cm(-3) h(-1)) measured with flow-through reactors (FTRs) on intact sediment slices. Acetylene-block FTR experiments indicate that complete denitrification accounts for approximately half of the nitrate reducing activity. The remaining NO(3)(-) reduction is due to incomplete denitrification and alternative reaction pathways, most likely dissimilatory nitrate reduction to NH(4)(+) (DNRA). Results of FTR experiments further indicate that increasing bottom water salinity may lead to a transient release of NH(4)(+) and dissolved organic carbon from the sediment, and enhance the rates of nitrate reduction and nitrite production. Increased salinity may thus, at least temporarily, increase the efflux of NH(4)(+) from the sediment to the surface water. This work shows that salinity affects the relative importance of denitrification compared to alternative nitrate reduction pathways, limiting the ability of denitrification to remove bioavailable nitrogen from aquatic ecosystems.

  19. Methane production in Dutch freshwater sediments: No substantial contribution by ciliates

    SciTech Connect

    Hoek, A.H.A.M. van; Hackstein, J.H.P.; Drift, C. vd

    1996-12-31

    Methanogenesis, the presence of ciliates, and a number of biotic and abiotic parameters were monitored over the course of a year in four different freshwater sediments near Nijmegen, The Netherlands. All sample places exhibited substantial biotic and abiotic differences. Whereas three of the sample places contained several species of ciliates, one location was devoid of substantial numbers of anaerobic protozoa. This location had the highest content of photosynthetic organisms, the lowest conductivity and lacked all kinds of ciliates. The degrees of pollution and the amounts of organic material present in the four sediments differed substantially. The annual course of the in situ temperature of the sediments was comparable, and neither superficial freezing of the sample places nor elevated summer temperatures caused dramatic variations in the methanogenic potential of the sediments. Direct counts of ciliates, their removal by electromigration, and the selective killing of protozoa by heat shock allowed the authors to calculate the contribution by the anaerobic ciliates to the methane emissions. In all three sediments that contained substantial amounts of ciliates, the contribution by these protozoa was less than 5--10%. Only during one exceptional month, the contribution by ciliates raised to 25% of the methane emissions.

  20. Microbial community structure in methane hydrate-bearing sediments of freshwater Lake Baikal.

    PubMed

    Kadnikov, Vitaly V; Mardanov, Andrey V; Beletsky, Alexey V; Shubenkova, Olga V; Pogodaeva, Tatiana V; Zemskaya, Tamara I; Ravin, Nikolai V; Skryabin, Konstantin G

    2012-02-01

    Gas hydrates in marine sediments have been known for many years but recently hydrates were found in the sediments of Lake Baikal, the largest freshwater basin in the world. Marine gas hydrates are associated with complex microbial communities involved in methanogenesis, methane oxidation, sulfate reduction and other biotransformations. However, the contribution of microorganisms to the formation of gas hydrates remains poorly understood. We examined the microbial communities in the hydrate-bearing sediments and water column of Lake Baikal using pyrosequencing of 16S rRNA genes. Aerobic methanotrophic bacteria dominated the water sample collected at the lake floor in the hydrate-bearing site. The shallow sediments were dominated by Archaea. Methanogens of the orders Methanomicrobiales and Methanosarcinales were abundant, whereas representatives of archaeal lineages known to perform anaerobic oxidation of methane, as well as sulfate-reducing bacteria, were not found. Affiliation of archaea to methanogenic rather than methane-oxidizing lineages was supported by analysis of the sequences of the methyl coenzyme M reductase gene. The deeper sediments located at 85-90 cm depth close to the hydrate were dominated by Bacteria, mostly assigned to Chloroflexi, candidate division JS1 and Caldiserica. Overall, our results are consistent with the biological origin of methane hydrates in Lake Baikal. PMID:22092495

  1. Effects of temperature and redox conditions on degradation of chlorinated phenols in freshwater sediments

    SciTech Connect

    Rogers, J.E.; Kohring, G.W.; Wiegel, J.

    1988-11-01

    The effect of temperature and redox conditions on the anaerobic degradation of 2,4-dichlorophenol (2,4-DCP) was investigated in anaerobic sediment slurries, prepared from local freshwater pond sediments. Under methanogenic conditions, 2,4-DCP dechlorination occurred in the temperature range between 5 and 50 C. Although dechlorination was not observed above 50 C, anaerobic bacterial activity was indicated by methane formation up to 60 C. In sediment samples from two sites and at all temperatures from 5 to 50 C, 2,4-DCP was transformed to 4-chlorophenol (4-CP). The 4-CP intermediate was subsequently degraded after an extended lag period. Adaptation periods for 2,4-DCP transformation decreased between 5 and 25 C, were essentially constant between 25 and 35 C, and increased between 35 and 40 C. Degradation rates increased exponentially between 15 and 30 C, had a second peak at 35 C, and decreased to about 5% of the peak activity by 40 C. In one sediment sample, an increase in degradation rates was observed following the minimum at 40 C, suggesting that at least two different organisms were involved in the 2,4-DCP dechlorination. Storage of the original sediment slurries for 2 months at 12 C resulted in increased adaptation times but did not affect the degradation rates.

  2. Derivation and selection of freshwater sediment quality values in Washington state

    SciTech Connect

    Cubbage, J.; Breidenbach, S.; Batts, D.

    1995-12-31

    To derive chemical-based Freshwater Sediment Quality Values (FSQV), bioassay data (Hyalella azteca, Microtox, Chironomus tentans, Daphnia magna, Ceriodaphnia dubia, and Hexagenia limbata) and chemistry data (metals, PAH, pesticide/PCBs, and phenols) were merged from 33 studies and 245 sites in Washington and Oregon into a single database. Apparent Effects Thresholds (AET) and Probable AETs (PAET: 95th percentile of no effects sites) were calculated for Hyalella azteca (n = 228) and Microtox. The efficiency and sensitivity of these values in predicting biological response from chemical concentrations were compared with Ontario`s Severe Effects Level (SEL), Environment Canada`s Probable Effects Level (PEL) and Threshold Effects Level (TEL), EPA`s Equilibrium Partitioning (EQP), and Washington`s marine Sediment management Standards (SMS). For PAH, dry weight normalized values for AETs and PAETs were significantly more sensitive and efficient than organic carbon normalized values. TEL was always the most sensitive and least efficient.

  3. Toxicity of phenanthrene in freshwater sediments to the rooted submersed macrophyte, Vallisneria spiralis.

    PubMed

    Yan, Zai S; Hu, Ying; Jiang, He L

    2011-08-01

    A study was conducted to determine the response of the rooted submersed macrophyte, Vallisneria spiralis to phenanthrene in freshwater sediments with initial phenanthrene concentrations from 0 to 80 mg kg(-1) dry sediment. The sensitivity of various morphological endpoints was evaluated after 90 days of exposure. The most sensitive toxicity test endpoints were those that reflected root growth. Toxicological sensitivity of the endpoints changed with the effect level selected. The toxicity threshold from a plot of the EC(10) values was 1-2 orders of magnitude lower than those calculated for the threshold from plots of the EC(25) or EC(50) values. In addition, stimulatory responses (hormesis) on root growth were observed at subtoxic concentrations of phenanthrene, and a hormetic model should thus be incorporated for ecological risk assessment. PMID:21643831

  4. A field investigation of the relationship between zinc and acid volatile sulfide concentrations in freshwater sediments

    USGS Publications Warehouse

    Ankley, Gerald T.; Liber, Karsten; Call, Daniel J.; Markee, Thomas P.; Canfield, Timothy J.; Ingersoll, Christopher G.

    1996-01-01

    Understanding relationships between cationic metals such as cadmium, copper, nickel, lead and zinc, and amorphous iron sulfides, measured as acid volatile sulfide (AVS), is key to predicting metal bioavailability and toxicity insediments. The objective of the present study was to assess seasonal and spatial variations of AVS in freshwater sediments contaminated with zinc. Sediments were sampled from three streams with varying levels of zinc contamination at two different times, March and June of 1995, representing cold- and warm-weather situations. Interstitial (pore) water concentrations of zinc, and solid phase concentrations of AVS and zinc were measured in surficial and deep sediment horizons. Toxicity tests (10-d) with the amphipodHyalella azteca were conducted using intact cores. Sediment zinc concentrations from six sites within the primary test stream differed by about five-fold, and also varied seasonally. Acid volatile sulfide concentrations were generally lower than those of zinc, and pore water zinc concentrations typically were elevated. There was a positive correlation between solid-phase AVS and zinc concentrations, suggesting that the system was dominated by zinc, as opposed to iron sulfides. In contrast to expectations arising from some studies of seasonal variations of AVS in iron-dominated systems, AVS concentrations were smaller in June than in March. However, this was likely due to a major storm event and associated sediment scouring before the June sampling, rather than to seasonal processes related to variations in temperature and dissolved oxygen. Based upon an indirect analysis of depth variations in AVS, there was some indication that zinc sulfide might be less prone to oxidation than iron sulfide. There was a strong correlation between toxicity of the sediment samples toH. azteca and interstitial water concentrations of zinc; however, the possible contribution of other contaminants to sediment toxicity cannot be dismissed.

  5. Sequential anaerobic degradation of 2,4-dichlorophenol in freshwater sediments

    SciTech Connect

    Zhang, X.; Wiegel, J. )

    1990-04-01

    2,4-Dichlorophenol (2,4-DCP) was anaerobically degraded in freshwater lake sediments. From observed intermediates in incubated sediment samples and from enrichment cultures, the following sequence of transformations was postulated. 2,4-DCP is dechlorinated to 4-chlorophenol (4-CP), 4-CP is dechlorinated to phenol, phenol is carboxylated to benzoate, and benzoate is degraded via acetate to methane and CO2; at least five different organisms are involved sequentially. The rate-limiting step was the transformation of 4-CP to phenol. Sediment-free enrichment cultures were obtained which catalyzed only the dechlorination of 2,4-DCP, the carboxylation of phenol, and the degradation of benzoate, respectively. Whereas the dechlorination of 2,4-DCP was not inhibited by H2, the dechlorination of 4-CP, and the transformation of phenol and benzoate were. Low concentrations of 4-CP inhibited phenol and benzoate degradation. Transformation rates and maximum concentrations allowing degradation were determined in both freshly collected sediments and in adapted samples: at 31{degrees}C, which was the optimal temperature for the dechlorination, the average adaptation time for 2,4-DCP, 4-CP, phenol, and benzoate transformations were 7, 37, 11 and 2 days, respectively. The maximal observed transformation rates for these compounds in acclimated sediments were 300, 78, 2, 130, and 2,080 micromol/liter(-1)/day(-1), respectively. The highest concentrations which still allowed the transformation of the compound in acclimated sediments were 3.1 m/M 2,4-DCP, 3.1 mM 4-CP, 13 mM phenol, and greater than 52 mM benzoate. The corresponding values were lower for sediments which had not been adapted for the transformation steps.

  6. Freshwater sediments and sludges: two important terrestrial sinks for emissions from damaged NPPs

    NASA Astrophysics Data System (ADS)

    Fischer, Helmut W.; Evangelia Souti, Maria; Ulbrich, Susanne; Hormann, Volker

    2013-04-01

    Surface deposition of radionuclides released from the damaged Fukushima NPPs is well documented and emissions to the Pacific Ocean and their distribution with time and space are also subject to monitoring and research. In both cases, solid matter (soil and sea sediment, respectively) acts as a sink for radioisotopes after their transport through air and water. The possible hazards from direct irradiation of workers and public and from entry of radionuclides into food chains are well recognized. Apart from direct deposition onto soil, plants, building roofs etc., aerosols and contaminated rainwater will reach surface waters, leading to long-term deposition in freshwater sediments (and possibly to interim contamination of drinking water). In populated and industrial areas, drained rainwater will enter the wastewater collection and treatment chain if a combined rain and wastewater sewer is used. Depending on the processes in the wastewater treatment plant and chemical element and speciation, the isotopes will either concentrate in treatment sludge or be released with the effluent to rivers and lakes and their sediments. The mentioned media may act as long-term storage for radioisotopes when disposed of properly, but can also contribute to direct irradiation of workers or public, lead to continuous releases to the environment and possibly enter the food chain in the same way as soil and sea sediments. It appears therefore essential to monitor these environmental compartments as well. However, very few data on Fukushima-related radioisotope concentration in sludges and freshwater sediments have been published to date. We will therefore compare data for regional surface deposition and related concentrations in surface water, river sediments and sewage sludge obtained in Europe during 1986 to published data from Japan in 2011 for the most important common short-lived (I-131, half-life = 8.02 d) and long-lived (Cs-137, half-life = 30.17 yr) isotopes. As in central Europe

  7. Temporal variation of nitrification rates in experimental freshwater sediments enriched with ammonia or nitrite.

    PubMed

    Stief, Peter; Schramm, Andreas; Altmann, Dörte; Beer, Dirk

    2003-10-01

    Abstract Two freshwater sediments (organic-poor and organic-rich) that contained their distinct natural microbial communities were incubated in experimental microcosms with either NH(4) (+) or NO(2) (-) in the overlying water. Microsensor measurements revealed the thin oxic surface layer as a site of initially high rates of nitrification, i.e. O(2), NH(4) (+), and NO(2) (-) consumption, and NO(3) (-) production. Unexpectedly, during the subsequent 4-week incubation NH(4) (+) consumption decreased in both sediment types and NO(2) (-) consumption decreased in the organic-rich sediment. In the organic-rich sediment O(2) consumption and NO(3) (-) production paralleled these decreases, i.e. the reduced NH(4) (+) and NO(2) (-) consumption rates were most probably due to reduced activity of nitrifiers. These microsensor data imply factors other than frequently suggested competition between nitrifiers and heterotrophs for NH(4) (+), NO(2) (-) or O(2) as causes for the loss of nitrification activity. We hypothesize that experimental manipulations (e.g. removal of macrofauna, redistribution of particulate organic matter, permanent nutrient enrichment) rendered the performance of the microbial community unstable. It is thus recommendable to restrict experiments in such commonly used model systems to the period of highest stability.

  8. Response of bacteria and meiofauna to iron oxide colloids in sediments of freshwater microcosms.

    PubMed

    Höss, Sebastian; Frank-Fahle, Béatrice; Lueders, Tillmann; Traunspurger, Walter

    2015-11-01

    The use of colloidal iron oxide (FeOx) in the bioremediation of groundwater contamination implies its increasing release into the environment and requires an assessment of its ecotoxicological risk. Therefore, microcosm experiments were carried out to investigate the impact of ferrihydrite colloids on the bacterial and meiofaunal communities of pristine freshwater sediments. The effects of ferrihydrite colloids were compared with those of ferrihydrite macroaggregates to discriminate between colloid-specific and general FeOx impacts. The influence of ferrihydrite colloids on the toxicity of sediment-bound fluoranthene was also considered. At high concentrations (496 mg Fe kg(-1) sediment dry wt), ferrihydrite colloids had a significant, but transient impact on bacterial and meiofaunal communities. Although bacterial community composition specifically responded to ferrihydrite colloids, a more general FeOx effect was observed for meiofauna. Bacterial activity responded most sensitively (already at 55 mg Fe kg(-1) dry wt) without the potential of recovery. Ferrihydrite colloids did not influence the toxicity of sediment-bound fluoranthene. Significant correlations between bacterial activity and meiofaunal abundances were indicative of trophic interactions between bacteria and meiofauna and therefore of the contribution of indirect food web effects to the observed impacts. The results suggest that the application of ferrihydrite colloids for remediation purposes in the field poses no risk for benthic communities, given that, with the exception of generic bacterial activity, any negative effects on communities were reversible.

  9. Equilibrium or indeterminate? Where sediment budgets fail: Sediment mass balance and adjustment of channel form, Green River downstream from Flaming Gorge Dam, Utah and Colorado

    NASA Astrophysics Data System (ADS)

    Grams, Paul E.; Schmidt, John C.

    2005-10-01

    This study examines bed and bank adjustment in the 105-km reach of the Green River immediately downstream from Flaming Gorge Dam by the use of historical aerial and oblique photographs, analysis of current and abandoned stream-gaging records, and field observations. Although this segment has been previously characterized as sediment deficient, these data show that sediment is accumulating in all reaches and that the bed has not degraded at any location where historical data are available. Adjustment is occurring through a combination of deposition of post-dam sediment and stabilization of pre-dam deposits, resulting in a 10-30% reduction in average width of the channel. All post-dam surfaces are colonized by woody riparian vegetation. The style of channel adjustment varies between geomorphically defined reaches. In canyons dominated by debris fans and gravel-bedded restricted meandering reaches, gravel bars have become inactive and accumulated fine sediment. In the sand-bedded meandering reaches, existing islands have increased in size and new mid-channel islands have formed. In all of these types of reaches, post-dam deposits line the banks and sediment has accumulated in side-channels that previously separated islands from the bank. These findings demonstrate that sediment budgets that show a balance between inputs and outputs cannot necessarily be interpreted to indicate channel equilibrium. A sediment mass balance for 150-km reach between the dam and the first long-term gage indicates approximate balance of inputs and outputs for the pre- and post-dam periods. When uncertainty in budget components is considered, the mass balance is indeterminate. Although the Green River may have been in approximate equilibrium in the pre-dam period, we have shown that channel width is decreasing in the post-dam period. The post-dam deposits constitute a small but a significant component of the sediment budget upstream from the first major tributary. Sediment is supplied to

  10. The impact of a hydroelectric power plant on the sediment load in downstream water bodies, Svartisen, northern Norway.

    PubMed

    Bogen, J; Bønsnes, T E

    2001-02-01

    When the Svartisen hydroelectric power plant was put into operation, extensive sediment pollution was observed in the downstream fjord area. This paper discusses the impact of the power plant and the contribution from various sources of sediment. Computation of the sediment load was based on samples collected one to four times per day. Grain size distribution analyses of suspended sediments were carried out and used as input in a routing model to study the movement of sediments through the system. Suspended sediment delivered to the fjord before the power station was constructed was measured as 8360 metric tons as an annual mean for a 12-year period. During the years 1995-1996 when the power plant was operating, the total suspended load through the power station was measured as 32609 and 30254 metric tons, respectively. Grain size distribution analyses indicate a major change in the composition of the sediments from 9% clay before the power plant was operative to 50-60% clay afterwards. This change, together with the increase in sediment load, is believed to be one of the main causes of the drastic reduction in secchi depths in the fjord. The effect of the suspended sediment load on the fjord water turbidity was evaluated by co-plotting secchi depth and power station water discharge. Measurements during 1995 and 1996 showed that at the innermost of these locations the water failed to attain the minimum requirement of 2 m secchi depth. In later years secchi depths were above the specified level. In 1997 and 1998 the conditions improved. At the more distal locality, the conditions were acceptable with only a few exceptions. A routing model was applied to data acquired at a location 2 km from the power station in order to calculate the contributions from various sediment sources. This model indicated that the contribution from reservoir bed erosion dominated in 1994 but decreased significantly in 1995. Future operation of the power station will mostly take place with

  11. A comparison of the response of Simocephalus mixtus (Cladocera) and Daphnia magna to contaminated freshwater sediments.

    PubMed

    Martínez-Jerónimo, Fernando; Cruz-Cisneros, Jade Lizette; García-Hernández, Leonardo

    2008-09-01

    The southeast region of Mexico is characterized by intensive oil industry activities carried out by the national public enterprise Petróleos Mexicanos (PEMEX). The freshwater lagoon "El Limón", located in the municipality of Macuspana, state of Tabasco, Mexico, has received over 40 years discharges of untreated waste waters from the Petrochemical Complex "Ciudad PEMEX", located on the border of the lagoon. To assess the toxicity of the sediments and, hence, to obtain information on the biological effects of these contaminating discharges, the cladoceran Simocephalus mixtus was used as a test organism in acute (48h) and chronic (12d) toxicity assays. For comparison purposes, bioassays were also conducted with the reference cladoceran Daphnia magna. The sediments of this lagoon contain important amounts of metals and hydrocarbons that have been accumulated over time; however, the acute tests only registered reduced lethal effects on the test organisms (maxima of 10% and 17% mortality for D. magna and S. mixtus, respectively). This may be due to low bioavailability of the pollutants present in the sediments. On the other hand, partial or total inhibition and delay in the start of reproduction, reduction in clutch sizes, reduced survival, as well as reduction in the size of adults and offspring were recorded in the chronic assays. The most evident chronic effects were found in S. mixtus; in this species, reproduction was inhibited up to 72%, whereas D. magna was only affected by 24%. We determined that S. mixtus is a more sensitive test organism than D. magna to assess whole-sediment toxicity in tropical environments, and that chronic exposure bioassays are required for an integrated sediment evaluation. The sediments from "El Limón" lagoon induced chronic intoxication responses and, therefore, remediation measures are urgently needed to recover environmental conditions suitable for the development of its aquatic biota.

  12. Diversity of sulfur-cycle prokaryotes in freshwater lake sediments investigated using aprA as the functional marker gene.

    PubMed

    Watanabe, Tomohiro; Kojima, Hisaya; Takano, Yoshinori; Fukui, Manabu

    2013-09-01

    The diversity of sulfate-reducing prokaryotes (SRPs) and sulfur-oxidizing prokaryotes (SOPs) in freshwater lake ecosystems was investigated by cloning and sequencing of the aprA gene, which encodes for a key enzyme in dissimilatory sulfate reduction and sulfur oxidation. To understand their diversity better, the spatial distribution of aprA genes was investigated in sediments collected from six geographically distant lakes in Antarctica and Japan, including a hypersaline lake for comparison. The microbial community compositions of freshwater sediments and a hypersaline sediment showed notable differences. The clones affiliated with Desulfobacteraceae and Desulfobulbaceae were frequently detected in all freshwater lake sediments. The SOP community was mainly composed of four major phylogenetic groups. One of them formed a monophyletic cluster with a sulfur-oxidizing betaproteobacterium, Sulfuricella denitrificans, but the others were not assigned to specific genera. In addition, the AprA sequences, which were not clearly affiliated to either SRP or SOP lineages, dominated the libraries from four freshwater lake sediments. The results showed the wide distribution of some sulfur-cycle prokaryotes across geographical distances and supported the idea that metabolic flexibility is an important feature for SRP survival in low-sulfate environments.

  13. Autotrophic Growth of Bacterial and Archaeal Ammonia Oxidizers in Freshwater Sediment Microcosms Incubated at Different Temperatures

    PubMed Central

    Wu, Yucheng; Ke, Xiubin; Hernández, Marcela; Wang, Baozhan; Dumont, Marc G.; Jia, Zhongjun

    2013-01-01

    Both bacteria and archaea potentially contribute to ammonia oxidation, but their roles in freshwater sediments are still poorly understood. Seasonal differences in the relative activities of these groups might exist, since cultivated archaeal ammonia oxidizers have higher temperature optima than their bacterial counterparts. In this study, sediment collected from eutrophic freshwater Lake Taihu (China) was incubated at different temperatures (4°C, 15°C, 25°C, and 37°C) for up to 8 weeks. We examined the active bacterial and archaeal ammonia oxidizers in these sediment microcosms by using combined stable isotope probing (SIP) and molecular community analysis. The results showed that accumulation of nitrate in microcosms correlated negatively with temperature, although ammonium depletion was the same, which might have been related to enhanced activity of other nitrogen transformation processes. Incubation at different temperatures significantly changed the microbial community composition, as revealed by 454 pyrosequencing targeting bacterial 16S rRNA genes. After 8 weeks of incubation, [13C]bicarbonate labeling of bacterial amoA genes, which encode the ammonia monooxygenase subunit A, and an observed increase in copy numbers indicated the activity of ammonia-oxidizing bacteria in all microcosms. Nitrosomonas sp. strain Is79A3 and Nitrosomonas communis lineages dominated the heavy fraction of CsCl gradients at low and high temperatures, respectively, indicating a niche differentiation of active bacterial ammonia oxidizers along the temperature gradient. The 13C labeling of ammonia-oxidizing archaea in microcosms incubated at 4 to 25°C was minor. In contrast, significant 13C labeling of Nitrososphaera-like archaea and changes in the abundance and composition of archaeal amoA genes were observed at 37°C, implicating autotrophic growth of ammonia-oxidizing archaea under warmer conditions. PMID:23455342

  14. Downstream assessment of chlorinated organic compounds in the bed-sediment of Aiba Stream, Iwo, South-Western, Nigeria.

    PubMed

    Olutona, Godwin O; Olatunji, Stephen O; Obisanya, Joshua F

    2016-01-01

    This study investigated levels and distribution pattern of chlorinated organic compounds (COCs) otherwise known as organochlorine pesticides in sediment samples at downstream of Aiba watercourse in Iwo, South-western Nigeria. Soxhlet extraction method followed by GC-ECD analysis were used to ascertain levels of COCs in the sediment samples collected from four different locations along the stream. Eighteen COCs were detected with trans permethrin and endosulfan sulfate having highest and lowest concentrations of 375.70 ± 689.41 and 0.03 ± 0.05 µg/g, respectively. The varying levels of COCs as obtained in this study were attributed to organochlorine pesticides contamination emanated from different agricultural practices and domestic sewage loads of the study area. PMID:26839760

  15. Anaerobic biodegradation of 2,4-dichlorophenol in freshwater lake sediments at different temperatures

    SciTech Connect

    Kohring, G.W.; Rogers, J.E.; Wiegel, J.

    1989-02-01

    Anaerobic degradation of 2,4-dichlorophenol (2,4-DCP) between 5 and 72 degrees C was investigated. Anaerobic sediment slurries prepared from local freshwater pond sediments were partitioned into anaerobic tubes or serum vials, which then were incubated separately at the various temperatures. Reductive 2,4-DCP dechlorination occurred only in the temperature range between 5 and 50/degree/C, although methane was formed up to 60 degrees C. In sediment samples from two sites and at all tested temperatures from 5 to 50 degrees C, 2,4-DCP was transformed to 4-chlorophenol (4-CP). The 4-CP intermediate was subsequently degraded after an extended lag period in the temperature range from 15 to 40/degree/C. Adaptation periods for 2,4-DCP transformation decreased between 5 and 25/degree/C, were essentially constant between 25 and 35/degree/C, and increased in the tubes incubated at temperatures between 35 and 40/degree/C. The degradation rates increased exponentially between 15 and 30/degree/C, had a second peak at 35/degree/C, and decreased to about 5% of the peak activity by 40/degree/C. In tubes from one sediment sample, incubated at temperatures above 40/degree/C, an increase in the degradation rate was observed following the minimum at 40/degree/C. This suggests that at least two different organisms were involved in the transformation of 2,4-DCP to 4-CP. Storage of the original sediment slurries for 2 months at 12/degree/C resulted in increased adaptation times, but did not affect the degradation rates.

  16. Comparison of the 10-day freshwater sediment toxicity tests using Hyalella azteca and Chironomus tentans

    SciTech Connect

    Becker, D.S.; Bigham, G.N.; Rose, C.D.

    1995-12-01

    Comparisons were made of the performance of the 10-d freshwater sediment toxicity tests using the amphipod Hyalella azteca and midge Chironomus tentans. Sediments were collected from eight stations in Onondaga Lake, New York, and represented a wide range of toxicity. The biological end points were survival, biomass, and body length. The two tests were compared on the basis of correspondence among relative values of the end points and ability to statistically discriminate adverse effects relative to control responses (i.e., discriminatory ability). Minimum detectable differences (MDDs) and adverse response ranges of the end points were used to further evaluate the discriminatory ability of the end points. Relative responses and discriminatory abilities of the end points of both tests were similar, despite numerous differences that exist among characteristics of the test species and end points. Significant concordance was found among all end points with respect to relative toxicity of sediments from the eight stations. Although MDDs and adverse response ranges of the various end points differed substantially, the observed positive correlation between those two variables resulted in all end points having similar discriminatory ability. Although amphipod biomass and body length have rarely been used as end points in 10-d tests, both end points provided results comparable to those of the other end points evaluated in the present study.

  17. Methane fluxes of freshwater sediments in relation to temperature and salt stress

    SciTech Connect

    Said, W.A.; Crow, S.A.

    1997-09-01

    Dynamics of methane fluxes of freshwater sediments in response to temperature changes and saline stress were investigated with a set of laboratory sediment microcosms. Sediments actively evolved methane over a temperature range of 0{degrees} to 45{degrees}C. Arrhenius plots were biphasic with a break point at approximately 25{degrees}C. {open_quotes}Ea{close_quotes} values were 101.8 {+-} (13.6) and 61.7 {+-} (11.4) kJ mol{sup -1} above and below 25{degrees}C, respectively. Temperature coefficients (Q10 values) show an approximate 9-fold increase of the CH{sub 4} emission rate for the 10{degrees}C rise in temperature over the range of 25{degrees} to 35{degrees}C. Methane fluxes were measured within 2 hours of saline intrusion of NaCI (0.05 or 0.15 M). The initial response to 0.15M NaCI addition was an episodic methane flux that ranged from 3. 1 to 14.2 ng microcosms{sup -1} min{sup -1} in the form of a pulse of < 2h interval. Measurements of CH{sub 4} fluxes on day 28 after saline intrusion revealed sink capacities that ranged between -0.45 and - 0.54 ng microcosm{sup -1} min{sup -1}.

  18. Metagenomic analysis reveals potential biodegradation pathways of persistent pesticides in freshwater and marine sediments.

    PubMed

    Fang, Hua; Cai, Lin; Yang, Ying; Ju, Feng; Li, Xiangdong; Yu, Yunlong; Zhang, Tong

    2014-02-01

    The abundance and diversity of biodegradation genes (BDGs) and potential degradation pathways of dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexane (HCH), and atrazine (ATZ) in freshwater and marine sediments were investigated by metagenomic analysis using 6 datasets (16Gb in total). The datasets were derived using Illumina high-throughput sequencing and were based on BLAST against self-established databases of BDGs, DDT degradation genes (DDGs), HCH degradation genes (HDGs), and ATZ degradation genes (ADGs). The results showed that the abundance and diversity of BDGs, DDGs, HDGs, and ADGs varied with sample source and locations. The lip and mnp genes, which encode for peroxidase, and the carA gene, which encodes for laccase, were detected as the dominant genes for degradation of organic pollutants. The hdt, hdg, and atzB genes, which encode for hydratase, dehalogenase, and ethylaminohydrolase, were found to be the most abundant genes involved in DDT, HCH, and ATZ degradation, respectively. The identified 69 genera capable of degrading organic pollutants were mostly affiliated with Proteobacteria (49.3%) and Actinobacteria (21.7%). Four genera, including Plesiocystis, Anaerolinea, Jannaschia, and Mycobacterium, were the major biodegradation populations in all sediments. In this study, the nearly complete biodegradation pathways of DDT and ATZ were found, and the partial degradation pathway of HCH was detected in all sediments.

  19. Anaerobic biodegradation of 2,4-dichlorophenol in freshwater lake sediments at different temperatures

    SciTech Connect

    Kohring, G.W.; Rogers, J.E.; Wiegel, J.

    1989-01-01

    Anaerobic degradation of 2,4-dichlorophenol (2,4-DCP) between 5 and 72C was investigated. Anaerobic sediment slurries prepared from local freshwater sediments were partitioned into anaerobic tubes or serum vials, which then were incubated separately at the various temperatures. Reductive 2,4-DCP dechlorination occurred only in the temperature range between 5 and 50C, although methane was formed up to 60C. In sediment samples from two sites and at all temperatures from 5 to 50C, 2,4-DCP was transformed to 4-chlorophenol (4-CP). The 4-CP intermediate was subsequently degraded after an extended lag period in the temperature range from 15 to 40C. Adaptation periods for 2,4-DCP transformation decreased between 5 and 25C, were essentially constant between 25 and 35C, and increased in the tubes incubated at temperatures between 35 and 40C. This suggests that at least two different organisms were involved in the transformation of 2,4-DCP to 4-CP.

  20. Dual radiotracer measurement of zoobenthos-mediated solute and particle transport in freshwater sediments

    NASA Astrophysics Data System (ADS)

    Krezoski, John R.; Robbins, John A.; White, David S.

    1984-09-01

    Gamma spectroscopy methods have been applied to determine the effects of Stylodrilus heringianus and Pontoporeia hoyi, two freshwater benthic macroinvertebrates, on the reworking of sediments and the transfer of solutes across the sediment-water interface. Natural lake sediments (sieved to remove organisms) and overlying water were contained in temperature-regulated rectangular plastic cells. A submillimeter layer of sediment solids labeled with 137Cs was deposited on the sediment interface while overlying water was spiked with 22Na. After addition of Stylodrilus (oligochaete worms) and Pontoporeia (crustacean amphipods) to these microcosms, the vertical distributions of 137Cs (a tracer of particle transport) and 22Na (a tracer of solute transport) were determined at daily to weekly intervals for 3 months by scanning the length of the cells with a well-collimated NaI detector. In cells with Stylodrilus, the 137Cs layer moved downward at a rate that decreased exponentially with time. The displacement of the layer is the result of the conveyor-belt feeding mode of this organism. The rate of marked layer burial is consistent with that of other freshwater annelids (0.18×10-5 cm d-1 individual-1 m-2; 11.6°C). The exponential decrease in burial rate is ascribed to uniformly distributed feeding of Stylodrilus within the feeding zone of 4.4 cm. In cells with Pontoporeia, 137Cs activity was smeared downward in time owing to eddy diffusive mixing of sediments over a small range (1-2 cm). In cells without worms, the veneer of Cs active material remained at the interface while the penetration of 22Na into sediments was consistent with diffusion in free solution with small corrections for sediment porosity and sorption (KD = 0.17). The effective diffusion coefficient De for 22Na in this cell (8.2×10-6 cm2 s-1) was essentially the same as that for a cell that had been inhabited by worms for 3 weeks and then poisoned with formalin just before addition of 22Na. Thus the

  1. Vertical Segregation and Phylogenetic Characterization of Ammonia-Oxidizing Bacteria and Archaea in the Sediment of a Freshwater Aquaculture Pond.

    PubMed

    Lu, Shimin; Liu, Xingguo; Ma, Zhuojun; Liu, Qigen; Wu, Zongfan; Zeng, Xianlei; Shi, Xu; Gu, Zhaojun

    2015-01-01

    Pond aquaculture is the major freshwater aquaculture method in China. Ammonia-oxidizing communities inhabiting pond sediments play an important role in controlling culture water quality. However, the distribution and activities of ammonia-oxidizing microbial communities along sediment profiles are poorly understood in this specific environment. Vertical variations in the abundance, transcription, potential ammonia oxidizing rate, and community composition of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in sediment samples (0-50 cm depth) collected from a freshwater aquaculture pond were investigated. The concentrations of the AOA amoA gene were higher than those of the AOB by an order of magnitude, which suggested that AOA, as opposed to AOB, were the numerically predominant ammonia-oxidizing organisms in the surface sediment. This could be attributed to the fact that AOA are more resistant to low levels of dissolved oxygen. However, the concentrations of the AOB amoA mRNA were higher than those of the AOA by 2.5- to 39.9-fold in surface sediments (0-10 cm depth), which suggests that the oxidation of ammonia was mainly performed by AOB in the surface sediments, and by AOA in the deeper sediments, where only AOA could be detected. Clone libraries of AOA and AOB amoA sequences indicated that the diversity of AOA and AOB decreased with increasing depth. The AOB community consisted of two groups: the Nitrosospira and Nitrosomonas clusters, and Nitrosomonas were predominant in the freshwater pond sediment. All AOA amoA gene sequences in the 0-2 cm deep sediment were grouped into the Nitrososphaera cluster, while other AOA sequences in deeper sediments (10-15 and 20-25 cm depths) were grouped into the Nitrosopumilus cluster.

  2. Vertical Segregation and Phylogenetic Characterization of Ammonia-Oxidizing Bacteria and Archaea in the Sediment of a Freshwater Aquaculture Pond.

    PubMed

    Lu, Shimin; Liu, Xingguo; Ma, Zhuojun; Liu, Qigen; Wu, Zongfan; Zeng, Xianlei; Shi, Xu; Gu, Zhaojun

    2015-01-01

    Pond aquaculture is the major freshwater aquaculture method in China. Ammonia-oxidizing communities inhabiting pond sediments play an important role in controlling culture water quality. However, the distribution and activities of ammonia-oxidizing microbial communities along sediment profiles are poorly understood in this specific environment. Vertical variations in the abundance, transcription, potential ammonia oxidizing rate, and community composition of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in sediment samples (0-50 cm depth) collected from a freshwater aquaculture pond were investigated. The concentrations of the AOA amoA gene were higher than those of the AOB by an order of magnitude, which suggested that AOA, as opposed to AOB, were the numerically predominant ammonia-oxidizing organisms in the surface sediment. This could be attributed to the fact that AOA are more resistant to low levels of dissolved oxygen. However, the concentrations of the AOB amoA mRNA were higher than those of the AOA by 2.5- to 39.9-fold in surface sediments (0-10 cm depth), which suggests that the oxidation of ammonia was mainly performed by AOB in the surface sediments, and by AOA in the deeper sediments, where only AOA could be detected. Clone libraries of AOA and AOB amoA sequences indicated that the diversity of AOA and AOB decreased with increasing depth. The AOB community consisted of two groups: the Nitrosospira and Nitrosomonas clusters, and Nitrosomonas were predominant in the freshwater pond sediment. All AOA amoA gene sequences in the 0-2 cm deep sediment were grouped into the Nitrososphaera cluster, while other AOA sequences in deeper sediments (10-15 and 20-25 cm depths) were grouped into the Nitrosopumilus cluster. PMID:26834709

  3. Vertical Segregation and Phylogenetic Characterization of Ammonia-Oxidizing Bacteria and Archaea in the Sediment of a Freshwater Aquaculture Pond

    PubMed Central

    Lu, Shimin; Liu, Xingguo; Ma, Zhuojun; Liu, Qigen; Wu, Zongfan; Zeng, Xianlei; Shi, Xu; Gu, Zhaojun

    2016-01-01

    Pond aquaculture is the major freshwater aquaculture method in China. Ammonia-oxidizing communities inhabiting pond sediments play an important role in controlling culture water quality. However, the distribution and activities of ammonia-oxidizing microbial communities along sediment profiles are poorly understood in this specific environment. Vertical variations in the abundance, transcription, potential ammonia oxidizing rate, and community composition of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in sediment samples (0–50 cm depth) collected from a freshwater aquaculture pond were investigated. The concentrations of the AOA amoA gene were higher than those of the AOB by an order of magnitude, which suggested that AOA, as opposed to AOB, were the numerically predominant ammonia-oxidizing organisms in the surface sediment. This could be attributed to the fact that AOA are more resistant to low levels of dissolved oxygen. However, the concentrations of the AOB amoA mRNA were higher than those of the AOA by 2.5- to 39.9-fold in surface sediments (0–10 cm depth), which suggests that the oxidation of ammonia was mainly performed by AOB in the surface sediments, and by AOA in the deeper sediments, where only AOA could be detected. Clone libraries of AOA and AOB amoA sequences indicated that the diversity of AOA and AOB decreased with increasing depth. The AOB community consisted of two groups: the Nitrosospira and Nitrosomonas clusters, and Nitrosomonas were predominant in the freshwater pond sediment. All AOA amoA gene sequences in the 0–2 cm deep sediment were grouped into the Nitrososphaera cluster, while other AOA sequences in deeper sediments (10–15 and 20–25 cm depths) were grouped into the Nitrosopumilus cluster. PMID:26834709

  4. Review of samples of tailings, soils and stream sediment adjacent to and downstream from the Ruth Mine, Inyo County, California

    USGS Publications Warehouse

    Rytuba, James J.; Kim, Christopher S.; Goldstein, Daniel N.

    2011-01-01

    The Ruth Mine and mill are located in the western Mojave Desert in Inyo County, California (fig. 1). The mill processed gold-silver (Au-Ag) ores mined from the Ruth Au-Ag deposit, which is adjacent to the mill site. The Ruth Au-Ag deposit is hosted in Mesozoic intrusive rocks and is similar to other Au-Ag deposits in the western Mojave Desert that are associated with Miocene volcanic centers that formed on a basement of Mesozoic granitic rocks (Bateman, 1907; Gardner, 1954; Rytuba, 1996). The volcanic rocks consist of silicic domes and associated flows, pyroclastic rocks, and subvolcanic intrusions (fig. 2) that were emplaced into Mesozoic silicic intrusive rocks (Troxel and Morton, 1962). The Ruth Mine is on Federal land managed by the U.S. Bureau of Land Management (BLM). Tailings from the mine have been eroded and transported downstream into Homewood Canyon and then into Searles Valley (figs. 3, 4, 5, and 6). The BLM provided recreational facilities at the mine site for day-use hikers and restored and maintained the original mine buildings in collaboration with local citizen groups for use by visitors (fig. 7). The BLM requested that the U.S. Geological Survey (USGS), in collaboration with Chapman University, measure arsenic (As) and other geochemical constituents in soils and tailings at the mine site and in stream sediments downstream from the mine in Homewood Canyon and in Searles Valley (fig. 3). The request was made because initial sampling of the site by BLM staff indicated high concentrations of As in tailings and soils adjacent to the Ruth Mine. This report summarizes data obtained from field sampling of mine tailings and soils adjacent to the Ruth Mine and stream sediments downstream from the mine on June 7, 2009. Our results permit a preliminary assessment of the sources of As and associated chemical constituents that could potentially impact humans and biota.

  5. EFFECTS OF FERRIC HYDROXIDE ON THE ANAEROBIC BIODEGRADATION KINETICS AND TOXICITY OF VEGETABLE OIL IN FRESHWATER SEDIMENTS

    EPA Science Inventory

    Biodegradation of vegetable oil in freshwater sediments exhibits self-inhibitory characteristics when it occurs under methanogenic conditions but not under iron-reducing conditions. The basis of the protective effect of iron was investigated by comparing its effects on oil biodeg...

  6. Sediment concentrations, flow conditions, and downstream evolution of two turbidity currents, Monterey Canyon, USA

    USGS Publications Warehouse

    Xu, Jingping; Octavio E. Sequeiros,; Noble, Marlene A.

    2014-01-01

    The capacity of turbidity currents to carry sand and coarser sediment from shallow to deep regions in the submarine environment has attracted the attention of researchers from different disciplines. Yet not only are field measurements of oceanic turbidity currents a rare achievement, but also the data that have been collected consist mostly of velocity records with very limited or no suspended sediment concentration or grain size distribution data. This work focuses on two turbidity currents measured in Monterey Canyon in 2002 with emphasis on suspended sediment from unique samples collected within the body of these currents. It is shown that concentration and grain size of the suspended material, primarily controlled by the source of the gravity flows and their interaction with bed material, play a significant role in shaping the characteristics of the turbidity currents as they travel down the canyon. Before the flows reach their normal or quasi-steady state, which is defined by bed slope, bed roughness, and suspended grain size, they might pass through a preliminary adjustment stage where they are subject to capacity-driven deposition, and release heavy material in excess. Flows composed of fine (silt/clay) sediments tend to be thicker than those with sands. The measured velocity and concentration data confirm that flow patterns differ between the front and body of turbidity currents and that, even after reaching normal state, the flow regime can be radically disrupted by abrupt changes in canyon morphology.

  7. Impact of Reservoir Sediment Scour on Water Quality in a Downstream Estuary.

    PubMed

    Cerco, Carl F; Noel, Mark R

    2016-05-01

    The Conowingo Reservoir is situated at the lower terminus of the Susquehanna ---River watershed, immediately above Chesapeake Bay. Since construction, the reservoir has been filling with sediment to the point where storage capacity is nearly exhausted. The potential for release of accumulated sediments, organic matter, and nutrients, especially through the action of storm scour, causes concern for water quality in Chesapeake Bay. We used hydrodynamic and eutrophication models to examine the effects of watershed loads and scour loads on bay water quality under total maximum daily load conditions. Results indicate that increased suspended solids loads are not a threat to bay water quality. For most conditions, solids scoured from the reservoir settle out before the season during which light attenuation is critical. The organic matter and nutrients associated with the solids are, however, detrimental. This material settles to the estuary bottom and is mineralized in bed sediments. Carbon diagenesis spurs oxygen consumption in bottom sediments and in the water column via release of chemical oxygen demand. The nutrients are recycled to the water column and stimulate algal production. As a result of a scour event, bottom-water dissolved oxygen declines up to 0.2 g m, although the decline is 0.1 g m or less when averaged over the summer season. Surface chlorophyll increases 0.1 to 0.3 mg m during the summer growing season. PMID:27136156

  8. Sediment concentrations, flow conditions, and downstream evolution of two turbidity currents, Monterey Canyon, USA

    NASA Astrophysics Data System (ADS)

    Xu, J. P.; Sequeiros, Octavio E.; Noble, Marlene A.

    2014-07-01

    The capacity of turbidity currents to carry sand and coarser sediment from shallow to deep regions in the submarine environment has attracted the attention of researchers from different disciplines. Yet not only are field measurements of oceanic turbidity currents a rare achievement, but also the data that have been collected consist mostly of velocity records with very limited or no suspended sediment concentration or grain size distribution data. This work focuses on two turbidity currents measured in Monterey Canyon in 2002 with emphasis on suspended sediment from unique samples collected within the body of these currents. It is shown that concentration and grain size of the suspended material, primarily controlled by the source of the gravity flows and their interaction with bed material, play a significant role in shaping the characteristics of the turbidity currents as they travel down the canyon. Before the flows reach their normal or quasi-steady state, which is defined by bed slope, bed roughness, and suspended grain size, they might pass through a preliminary adjustment stage where they are subject to capacity-driven deposition, and release heavy material in excess. Flows composed of fine (silt/clay) sediments tend to be thicker than those with sands. The measured velocity and concentration data confirm that flow patterns differ between the front and body of turbidity currents and that, even after reaching normal state, the flow regime can be radically disrupted by abrupt changes in canyon morphology.

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

    PubMed

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

    2015-11-01

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

  10. Cytotoxicity of TiO{sub 2} nanoparticles towards freshwater sediment microorganisms at low exposure concentrations

    SciTech Connect

    Kumari, Jyoti; Kumar, Deepak; Mathur, Ankita; Naseer, Arif; Kumar, Ravi Ranjan; Thanjavur Chandrasekaran, Prathna; Chaudhuri, Gouri; Pulimi, Mrudula; Raichur, Ashok M.; Babu, S.; Chandrasekaran, Natarajan; Nagarajan, R.; Mukherjee, Amitava

    2014-11-15

    There is a persistent need to assess the effects of TiO{sub 2} nanoparticles on the aquatic ecosystem owing to their increasing usage in consumer products and risk of environmental release. The current study is focused on TiO{sub 2} nanoparticle-induced acute toxicity at sub-ppm level (≤1 ppm) on the three different freshwater sediment bacterial isolates and their consortium under two different irradiation (visible light and dark) conditions. The consortium of the bacterial isolates was found to be less affected by the exposure to the nanoparticles compared to the individual cells. The oxidative stress contributed considerably towards the cytotoxicity under both light and dark conditions. A statistically significant increase in membrane permeability was noted under the dark conditions as compared to the light conditions. The optical and fluorescence microscopic images showed aggregation and chain formation of the bacterial cells, when exposed to the nanoparticles. The electron microscopic (SEM, TEM) observations suggested considerable damage of cells and bio-uptake of nanoparticles. The exopolysaccrides (EPS) production and biofilm formation were noted to increase in the presence of the nanoparticles, and expression of the key genes involved in biofilm formation was studied by RT-PCR. - Highlights: • Toxicity of NPs towards freshwater sediment bacteria at sub-ppm concentrations. • Decreased toxicity of the nanoparticles in the consortium of microorganisms. • Enhanced bacterial resistance through EPS and biofilm formation in the presence of NPs. • Considerable surface damage of cells and internalization of NPs. • Gene expression analyses related to biofilm formation in the presence of NPs.

  11. The trace element analysis in freshwater fish species, water and sediment in Iyidere stream (Rize-Turkey).

    PubMed

    Verep, Bulent; Mutlu, Cengiz; Apaydin, Gokhan; Cevik, Ugur

    2012-07-15

    Many environmental problems like dam construction, agricultural debris, flooding and industrial establishments threaten Iyidere stream (Rize, Turkey) on the southeastern coast of the Black Sea (Turkey). The trace element concentrations in water, fish and sediments in lyidere stream (Rize, Turkey) were investigated in this study. The concentration of six different elements in ten freshwater fish species and sediment was determined using energy dispersive X-ray fluorescence method. A radioisotope excited X-ray fluorescence analysis using the method of multiple standard addition is applied for the elemental analysis of fish and sediments. Water samples for trace metals were analyzed using standard spectrophotometry methods. A qualitative analysis of spectral peaks showed that ten different freshwater fish samples (Chondrostoma colchicum, Chalcalburnus chalcoides, Salmo trutta labrax, Alburnoides bipunctatus, Leuciscus cephalus, Barbus taurus escherichia, Capoeta tinca, Neogobius kessleri, Rutilus frisii, Lampetra lanceolata) and sediment contained phosphorus (P), sulphur (S), chlorine (Cl), potassium (K), calcium (Ca) and titanium (Ti). Heavy metals as toxic elements for biota (Pb, Cd, Hg, Zn and Mn etc.) were not detected in fish, water and sediments. Thus, It can be declared that freshwater fish of Iyidere does not contains health risks for consumers in terms of metal pollution.

  12. Ecotoxicity of fluvial sediments downstream of the Ajka red mud spill, Hungary.

    PubMed

    Klebercz, Orsolya; Mayes, William M; Ánton, Aron Dániel; Feigl, Viktória; Jarvis, Adam P; Gruiz, Katalin

    2012-08-01

    An integrated assessment of biological activity and ecotoxicity of fluvial sediments in the Marcal river catchment (3078 km(2)), western Hungary, is presented following the accidental spill of bauxite processing residue (red mud) in Ajka. Red mud contaminated sediments are characterised by elevated pH, elevated trace element concentrations (e.g. As, Co, Cr, V), high exchangeable Na, and induce an adverse effect on test species across a range of trophic levels. While background contamination of the river system is highlighted by adverse effects on some test species at sites unaffected by red mud, the most pronounced toxic effects apparent in Vibrio fischeri bioluminescence inhibition, Lemna minor bioassay and Sinapis alba root and shoot growth occur at red mud depositional hotspots in the lower Torna Creek and upper Marcal. Heterocypris incongruens bioassays show no clear patterns, although the most red mud-rich sites do exert an adverse effect. Red mud does however appear to induce an increase in the density of aerobic and facultative anaerobic bacterial communities when compared with unaffected sediments and reference sites. Given the volume of material released in the spill, it is encouraging that the signal of the red mud on aquatic biota is visible at a relatively small number of sites. Gypsum-affected samples appear to induce an adverse effect in some bioassays (Sinapis alba and Heterocypris incongruens), which may be a feature of fine grain size, limited nutrient supply and greater availability of trace contaminants in the channel reaches that are subject to intense gypsum dosing. Implications for monitoring and management of the spill are discussed. PMID:22772744

  13. Biodegradation of trichloroethylene and its anaerobic daughter products in freshwater wetland sediments

    USGS Publications Warehouse

    Lorah, M.M.; Olsen, L.D.

    2001-01-01

    Laboratory microcosms were prepared under methanogenic, sulfate-reducing, and aerobic conditions using sediment and groundwater from a freshwater wetland that is a discharge area for a trichloroethylene (TCE) to evaluate potential biodegradation rates of TCE and its anaerobic daughter products (cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, and vinyl chloride (VC)). Anaerobic degradation of TCE was about an order of magnitude faster under methanogenic conditions than under sulfate-reducing conditions. Both 12DCE and VC were found under sulfate-reducing conditions in the microcosms containing the wetland sediment, but their production, especially for VC, was substantially slower than under methanogenic conditions. Methane concentrations remained approximately constant (when losses in the formalin-amended controls are considered) in the microcosms amended with TCE and increased in the microcosms amended with the 12DCE isomers and VC during the first 18-25 days of incubation. The most rapid decrease in concentrations of TCE, cis-12DCE, trans-12DCE, and VC was found after aerobic methane-oxidizing conditions were definitely established.

  14. Dominating Role of an Unusual Magnetotactic Bacterium in the Microaerobic Zone of a Freshwater Sediment

    PubMed Central

    Spring, Stefan; Amann, Rudolf; Ludwig, Wolfgang; Schleifer, Karl-Heinz; van Gemerden, Hans; Petersen, Nikolai

    1993-01-01

    A combination of polymerase chain reaction-assisted rRNA sequence retrieval and fluorescent oligonucleotide probing was used to identify in situ a hitherto unculturable, big, magnetotactic, rod-shaped organism in freshwater sediment samples collected from Lake Chiemsee. Tentatively named “Magnetobacterium bavaricum,” this bacterium is evolutionarily distant from all other phylogenetically characterized magnetotactic bacteria and contains unusually high numbers of magnetosomes (up to 1,000 magnetosomes per cell). The spatial distribution in the sediment was studied, and up to 7 × 105 active cells per cm3 were found in the microaerobic zone. Considering its average volume (25.8 ± 4.1 μm3) and relative abundance (0.64 ± 0.17%), “M. bavaricum” may account for approximately 30% of the microbial biovolume and may therefore be a dominant fraction of the microbial community in this layer. Its microhabitat and its high content of sulfur globules and magnetosomes suggest that this organism has an iron-dependent way of energy conservation which depends on balanced gradients of oxygen and sulfide. Images PMID:16349008

  15. Direct and indirect effects of copper-contaminated sediments on the functions of model freshwater ecosystems.

    PubMed

    Gardham, Stephanie; Chariton, Anthony A; Hose, Grant C

    2015-01-01

    Copper is acutely toxic to, and directly affects, primary producers and decomposers, which are key players in essential processes such as the nutrient cycle in freshwater ecosystems. Even though the indirect effects of metals (for example effects due to changes in species interactions) may be more common than direct effects, little is known about the indirect effects of copper on primary producers and decomposers. The effects of copper on phytoplankton, macrophytes, periphyton and organic matter decomposition in an outdoor lentic mesocosm facility were assessed, and links between the responses examined. Copper directly decreased macrophyte growth, subsurface organic matter decomposition, and the potential for high phytoplankton Chlorophyll a concentrations. However, periphyton cover and organic matter decomposition on the surface of the sediment were stimulated by the presence of copper. These latter responses were attributed to indirect effects, due to a reduction in grazing pressure from snails, particularly Physa acuta, in the higher copper-contaminated mesocosms. This permitted the growth of periphyton and other heterotrophs, ultimately increasing decomposition at the sediment surface. The present study demonstrates the pronounced influence indirect effects may have on ecological function, findings that may not be observed in traditional laboratory studies (which utilize single species or simplistic communities).

  16. Effect of indigenous animals on chronic end points in freshwater sediment toxicity tests

    SciTech Connect

    Reynoldson, T.B.; Day, K.E.; Clarke, C.; Milani, D. )

    1994-06-01

    Sediment toxicity tests were conducted using three species of benthic invertebrates, Chironomus riparius, Hyalella azteca, and Hexagenia limbata, with various densities of the oligochaete worm Tubifex tubifex. It was shown that indigenous animals, simulated by the presence of Tubifex tubifex, did not affect survival of the test species (P [>=] 0.05) but did reduce growth in all three test species and in two species at the lowest tested densities, equivalent to 1,460 worms per square meter. At densities of Tubifex tubifex equivalent to 20,000 m[sup [minus]2], the growth of Chironomus riparius was reduced by >90%, Hyalella azteca by >60%, and Hexagenia limbata by almost 50%. The densities of oligochaetes are equivalent to those found in many contaminated sites. Therefore, it is concluded that the presence of indigenous organisms can confound the interpretation of toxicity test results, based on chronic end points. It is recommended that removal of organisms by considered before toxicity tests are conducted with freshwater sediments from sites with large populations of benthic invertebrates, especially oligochaete worms.

  17. Influence of freshwater sediment on the survival of Escherichia coli and Salmonella sp. as measured by three methods of enumeration.

    PubMed

    Fish, J T; Pettibone, G W

    1995-05-01

    Growth and survival of enteric bacteria in freshwater sediments should be of concern to public health officials because of potential contributions of bacteria to the water column. Bacteria densities were measured in sediment and water using direct counts (DC), direct viable counts (DVC) and standard plate counts (PC). Both Salmonella sp. and Escherichia coli survived in microcosms containing autoclaved water and sediment for at least 28 d, as measured by all three methods of enumeration. Moreover, when bacteria were enumerated from sediment-containing microcosms, the DC, DVC and PC values were equivalent. Plate counts showed that both organisms were present at high densities on day 56. In addition, parallel platings on MacConkey agar of E. coli from microcosms containing sediment gave results identical to PC values, indicating that E. coli was not stressed in these microcosms. In microcosms containing water only, E. coli densities declined gradually over 2 weeks by all three measures of enumeration. By day 14, only 58% of total DC was viable as measured by DVC. Due to the protective nature of sediments, the use of standard media may be adequate to enumerate E. coli from some freshwater sediments.

  18. Field validation of 10-day freshwater sediment toxicity tests using Hyalella azteca and Chironomus tentans

    SciTech Connect

    Becker, D.S.; Bigham, G.N.

    1995-12-31

    Two of the toxicity tests commonly used to evaluate freshwater sediments are the 10-day amphipod (Hyalella azteca) and chironomid (Chironomus tentans) tests. EPA and ASTM have recently developed standardized protocols for these tests. Although both tests are considered sensitive indicators of sediment toxicity, little information exists on how well test results correspond to adverse biological effects in the field. In this study, the lethal and sublethal (i.e., biomass) responses of the two toxicity tests were compared with alterations of benthic macroinvertebrate assemblages (i.e., benthic effects) at 56 stations in Onondaga Lake, New York. The lake has received municipal and industrial discharges for more than 100 years, and sediment chemical concentrations range widely throughout the lake. Toxicity results for Onondaga Lake were compared with reference conditions using the t-test, and benthic effects were determined using classification analysis of log-transformed taxa abundances. In general, a relatively high level of agreement was found between results of the toxicity tests and alterations of benthic assemblages. Significant (P < 0.05) correlations were found between all toxicity test endpoints and taxa richness of benthic assemblages. In addition, significant concordance (P {le} 0.01, binomial test) was found between toxicity designations for the 56 stations based on toxicity tests and toxicity designations based on benthic effects. Despite the general level of agreement among the various biological indicators, chironomid biomass and benthic effects were found to be the most sensitive indicators of toxicity, whereas amphipod survival and biomass were the least sensitive indicators. This study suggests that results of the 10-day amphipod and chironomid toxicity tests are highly predictive of adverse biological effects in the field.

  19. Microbial community structures in anoxic freshwater lake sediment along a metal contamination gradient.

    PubMed

    Gough, Heidi L; Stahl, David A

    2011-03-01

    Contamination, such as by heavy metals, has frequently been implicated in altering microbial community structure. However, this association has not been extensively studied for anaerobic communities, or in freshwater lake sediments. We investigated microbial community structure in the metal-contaminated anoxic sediments of a eutrophic lake that were impacted over the course of 80 years by nearby zinc-smelting activities. Microbial community structure was inferred for bacterial, archaeal and eukaryotic populations by evaluating terminal restriction fragment length polymorphism (TRFLP) patterns in near-surface sediments collected in triplicate from five areas of the lake that had differing levels of metal contamination. The majority of the fragments in the bacterial and eukaryotic profiles showed no evidence of variation in association with metal contamination levels, and diversity revealed by these profiles remained consistent even as metal concentrations varied from 3000 to 27,000 mg kg(-1) total Zn, 0.125 to 11.2 μ pore water Zn and 0.023 to 5.40 μM pore water As. Although most archaeal fragments also showed no evidence of variation, the prevalence of a fragment associated with mesophilic Crenarchaeota showed significant positive correlation with total Zn concentrations. This Crenarchaeota fragment dominated the archaeal TRFLP profiles, representing between 35% and 79% of the total measured peak areas. Lake DePue 16S rRNA gene sequences corresponding to this TRFLP fragment clustered with anaerobic and soil mesophilic Crenarchaeota sequences. Although Crenarchaeota have been associated with metal-contaminated groundwater and soils, this is a first report (to our knowledge) documenting potential increased prevalence of Crenarchaeota associated with elevated levels of metal contamination.

  20. Limited reduction of ferrihydrite encrusted by goethite in freshwater sediment.

    PubMed

    Kikuchi, S; Makita, H; Konno, U; Shiraishi, F; Ijiri, A; Takai, K; Maeda, M; Takahashi, Y

    2016-07-01

    Many physical and chemical processes control the extent of Fe(III) oxyhydroxide reduction by dissimilatory Fe(III)-reducing bacteria. The surface precipitation of secondary Fe minerals on Fe(III) oxyhydroxides limits the extent of microbial Fe(III) reduction, but this phenomenon has not yet been observed in nature. This paper reports the observation of secondary Fe-mineral (goethite) encrustation on ferrihydrite surface within freshwater sediment up to 10 cm deep. The sediment surface was characterized by the predominance of ferrihydrites with biogenic stalks and sheaths. An Fe(II)-oxidizing bacterium (Gallionellaceae) was detected by 16S rRNA gene analysis at sediment depths of 1 and 2 cm. Fe(2+) concentration in the sediment pore water was relatively higher at 2-4 cm depths. The 16S rRNA genes affiliated with dissimilatory Fe(III)-reducing bacteria were detected at 1, 2, and 4 cm depths. The results of the Fe K-edge extended X-ray absorption fine structure (EXAFS) analysis suggested the presence of goethite and siderite at depths below 3 cm. However, the change in the Fe-mineral composition was restricted to sediment depths between 3 and 4 cm, despite the presence of abundant ferrihydrite at depths below 4 cm. An increase in CH4 concentration was observed at deeper than 6 cm. Stable isotopic analysis of CH4 in the pore water indicated that acetoclastic CH4 occurred at depths below 7 cm. Transmission electron microscope observations suggested the presence of goethite and siderite on stalks and sheaths at depths below 3 cm. Results from conversion electron yield EXAFS analysis suggested that goethite dominated at 10 cm depth, thereby indicating that ferrihydrite was encrusted by goethite at this depth. Moreover, the incomplete reduction of ferrihydrite below depths of 4 cm was not due to the lack of organic carbon, but was possibly due to the surface encrustation of goethite on ferrihydrite. PMID:27027643

  1. Speciation and Degrees of Contamination of Metals in Sediments from Upstream and Downstream Reaches along the Catchment of the Southern Bohai Sea, China

    PubMed Central

    Xu, Li; Li, Jing

    2015-01-01

    Environmental processes and biological community structures change along fluvial gradients within coastal river basins; the accumulation and associated risk of metal contamination would also be expected to change from upstream to downstream reaches. Speciation and degrees of contamination of metals in sediments from the upstream and downstream of river catchments of the southern Bohai Sea were investigated. The mean concentrations of Cu, Zn, Cr, Ni, Cd and Pb from upstream reaches were 82.6, 157, 63.6, 26.6, 0.18 and 24.9 mg/kg, respectively. The mean concentrations of Cu, Zn, Cr, Ni, Cd and Pb from downstream reaches were 38.0, 66.0, 38.9, 18.1, 0.16 and 24.0 mg/kg, respectively. Most of the Cu, Zn, Cr, Ni and Pb in sediments from both the upstream and downstream reaches was mainly associated with the residual fraction. However, Cd was preferentially bound to the exchangeable phase. A cluster analysis was used to study the degree of association between sites, and three distinct clusters were identified in both upstream and downstream sediments. A correlation analysis was conducted to determine the extent of association among metals and showed that metals in sediments from the upstream reaches have more affinity than those in the downstream area. Sediment quality guidelines were used to evaluate potential risks. The risks from Zn, Cr and Ni in the upstream reaches were higher than those from downstream reaches; however, the other three metals (Cu, Pb and Cd) showed opposite results. PMID:26184267

  2. Speciation and Degrees of Contamination of Metals in Sediments from Upstream and Downstream Reaches along the Catchment of the Southern Bohai Sea, China.

    PubMed

    Xu, Li; Li, Jing

    2015-07-01

    Environmental processes and biological community structures change along fluvial gradients within coastal river basins; the accumulation and associated risk of metal contamination would also be expected to change from upstream to downstream reaches. Speciation and degrees of contamination of metals in sediments from the upstream and downstream of river catchments of the southern Bohai Sea were investigated. The mean concentrations of Cu, Zn, Cr, Ni, Cd and Pb from upstream reaches were 82.6, 157, 63.6, 26.6, 0.18 and 24.9 mg/kg, respectively. The mean concentrations of Cu, Zn, Cr, Ni, Cd and Pb from downstream reaches were 38.0, 66.0, 38.9, 18.1, 0.16 and 24.0 mg/kg, respectively. Most of the Cu, Zn, Cr, Ni and Pb in sediments from both the upstream and downstream reaches was mainly associated with the residual fraction. However, Cd was preferentially bound to the exchangeable phase. A cluster analysis was used to study the degree of association between sites, and three distinct clusters were identified in both upstream and downstream sediments. A correlation analysis was conducted to determine the extent of association among metals and showed that metals in sediments from the upstream reaches have more affinity than those in the downstream area. Sediment quality guidelines were used to evaluate potential risks. The risks from Zn, Cr and Ni in the upstream reaches were higher than those from downstream reaches; however, the other three metals (Cu, Pb and Cd) showed opposite results. PMID:26184267

  3. Assimilation of remote sensing observations into a sediment transport model of China's largest freshwater lake: spatial and temporal effects.

    PubMed

    Zhang, Peng; Chen, Xiaoling; Lu, Jianzhong; Zhang, Wei

    2015-12-01

    Numerical models are important tools that are used in studies of sediment dynamics in inland and coastal waters, and these models can now benefit from the use of integrated remote sensing observations. This study explores a scheme for assimilating remotely sensed suspended sediment (from charge-coupled device (CCD) images obtained from the Huanjing (HJ) satellite) into a two-dimensional sediment transport model of Poyang Lake, the largest freshwater lake in China. Optimal interpolation is used as the assimilation method, and model predictions are obtained by combining four remote sensing images. The parameters for optimal interpolation are determined through a series of assimilation experiments evaluating the sediment predictions based on field measurements. The model with assimilation of remotely sensed sediment reduces the root-mean-square error of the predicted sediment concentrations by 39.4% relative to the model without assimilation, demonstrating the effectiveness of the assimilation scheme. The spatial effect of assimilation is explored by comparing model predictions with remotely sensed sediment, revealing that the model with assimilation generates reasonable spatial distribution patterns of suspended sediment. The temporal effect of assimilation on the model's predictive capabilities varies spatially, with an average temporal effect of approximately 10.8 days. The current velocities which dominate the rate and direction of sediment transport most likely result in spatial differences in the temporal effect of assimilation on model predictions.

  4. Preparation and characterization of nickel-spiked freshwater sediments for toxicity tests: toward more environmentally realistic nickel partitioning.

    PubMed

    Brumbaugh, William G; Besser, John M; Ingersoll, Christopher G; May, Thomas W; Ivey, Chris D; Schlekat, Christian E; Garman, Emily Rogevich

    2013-11-01

    Two spiking methods were compared and nickel (Ni) partitioning was evaluated during a series of toxicity tests with 8 different freshwater sediments having a range of physicochemical characteristics. A 2-step spiking approach with immediate pH adjustment by addition of NaOH at a 2:1 molar ratio to the spiked Ni was effective in producing consistent pH and other chemical characteristics across a range of Ni spiking levels. When Ni was spiked into sediment having a high acid-volatile sulfide and organic matter content, a total equilibration period of at least 10 wk was needed to stabilize Ni partitioning. However, highest spiking levels evidently exceeded sediment binding capacities; therefore, a 7-d equilibration in toxicity test chambers and 8 volume-additions/d of aerobic overlying water were used to avoid unrealistic Ni partitioning during toxicity testing. The 7-d pretest equilibration allowed excess spiked Ni and other ions from pH adjustment to diffuse from sediment porewater and promoted development of an environmentally relevant, 0.5- to 1-cm oxic/suboxic sediment layer in the test chambers. Among the 8 different spiked sediments, the logarithm of sediment/porewater distribution coefficient values (log Kd ) for Ni during the toxicity tests ranged from 3.5 to 4.5. These Kd values closely match the range of values reported for various field Ni-contaminated sediments, indicating that testing conditions with our spiked sediments were environmentally realistic.

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

    USGS Publications Warehouse

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

    2009-01-01

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

  6. Sediment characteristics in the San Antonio River Basin downstream from San Antonio, Texas, and at a site on the Guadalupe River downstream from the San Antonio River Basin, 1966-2013

    USGS Publications Warehouse

    Crow, Cassi L.; Banta, J. Ryan; Opsahl, Stephen P.

    2014-01-01

    San Antonio and surrounding municipalities in Bexar County, Texas, are in a rapidly urbanizing region in the San Antonio River Basin. The U.S. Geological Survey, in cooperation with the San Antonio River Authority and the Texas Water Development Board, compiled historical sediment data collected between 1996 and 2004 and collected suspended-sediment and bedload samples over a range of hydrologic conditions in the San Antonio River Basin downstream from San Antonio, Tex., and at a site on the Guadalupe River downstream from the San Antonio River Basin during 2011–13. In the suspended-sediment samples collected during 2011–13, an average of about 94 percent of the particles was less than 0.0625 millimeter (silt and clay sized particles); the 50 samples for which a complete sediment-size analysis was performed indicated that an average of about 69 percent of the particles was less than 0.002 millimeter. In the bedload samples collected during 2011–13, an average of 51 percent of sediment particles was sand-sized particles in the 0.25–0.5 millimeter-size range. In general, the loads calculated from the samples indicated that bedload typically composed less than 1 percent of the total sediment load. A least-squares log-linear regression was developed between suspended-sediment concentration and instantaneous streamflow and was used to estimate daily mean suspended-sediment loads based on daily mean streamflow. The daily mean suspended-sediment loads computed for each of the sites indicated that during 2011–12, the majority of the suspended-sediment loads originated upstream from the streamflow-gaging station on the San Antonio River near Elmendorf, Tex. A linear regression relation was developed between turbidity and suspended-sediment concentration data collected at the San Antonio River near Elmendorf site because the high-resolution data can facilitate understanding of the complex suspended-sediment dynamics over time and throughout the river basin.

  7. Validation and sensitivity comparisons of micro-scale toxicity tests for the evaluation of freshwater sediment toxicity

    SciTech Connect

    Riebel, P.; Bureau, J.; Blaise, C.; Michaud, J.R.

    1995-12-31

    A three-year study is currently underway to develop a representative and cost-effective battery of toxicity tests for evaluating freshwater sediment and porewater toxicity. Among the tests currently being evaluated are the following: Microtox{trademark} chronic test, Microtox{trademark} solid-phase test, Microtox{trademark} liquid phase test, Thamnotoxkit F{trademark}, Rotoxkit F{trademark}, Daphnia magna IQ test{trademark}, Sediment Toxkit, SOS Chromotest, a Selenastrum capricornutum short exposure assay, and trout hepatocyte assays. Conventional sediment tests with Chironomus tentans, Hyalella azteca and Lumbriculus variegatus, as well as benthic macroinvertebrate community assessments and sediment chemical characterizations are being conducted at two contaminated sites. Toxicity test reproducibility, sensitivity, practicality, cost and ecological relevance are discussed.

  8. Desulfotomaculum intricatum sp. nov., a sulfate reducer isolated from freshwater lake sediment.

    PubMed

    Watanabe, Miho; Kojima, Hisaya; Fukui, Manabu

    2013-10-01

    A novel spore-forming, sulfate-reducing bacterium, strain SR45(T), was isolated from sediment of a freshwater lake, Lake Mizugaki, in Japan. Cells of strain SR45 were rod-shaped (1.0-1.5×2.0-5.0 µm) and weakly motile; Gram staining and the KOH lysis test were negative. For growth, the optimum pH was 6.4-6.8 and the optimum temperature was 42-45 °C. Strain SR45(T) used sulfate, thiosulfate, sulfite and elemental sulfur as electron acceptors but not Fe(III). The G+C content of the genomic DNA was 41.1 mol%. Phylogenetic analyses based on genes for the 16S rRNA and DNA gyrase (gyrB) revealed that the isolated strain belonged to the family Peptococcaceae in the class Clostridia. The closest relative is Desulfotomaculum acetoxidans 5575(T), with 16S rRNA gene sequence similarity of 92-94 %. It is suggested that the strain is the second isolated member of Desulfotomaculum subcluster Ie. The isolate had multiple 16S rRNA gene copies, with 13 different sequences. On the basis of phylogenetic and phenotypic characterization, the name Desulfotomaculum intricatum sp. nov. is proposed, with the type strain SR45(T) ( = NBRC 109411(T) = DSM 26801(T)). PMID:23584284

  9. Effects of clay minerals and organic matter in formulated sediments on the bioavailability of sediment-associated uranium to the freshwater midge, Chironomus dilutus.

    PubMed

    Crawford, Sarah E; Liber, Karsten

    2015-11-01

    It is well established that bioavailability influences metal toxicity in aquatic ecosystems. However, the factors and mechanisms that influence uranium (U) bioavailability and toxicity in sediment have not been thoroughly evaluated, despite evidence that suggests different sediment components can influence the sorption and interaction of some metals. Given that dissolved U is generally accepted as being the primary bioavailable fraction of U, it is hypothesized that adsorption and interaction of U with different sediment components will influence the bioavailability of U in sediment. We investigated the effects of key sediment physicochemical properties on the bioavailability of U to a model freshwater benthic invertebrate, Chironomus dilutus. Several 10-day spiked sediment bioaccumulation experiments were performed, exposing C. dilutus larvae to a variety of formulated sediments spiked with different concentrations of U (5, 50 and/or 200 mg U/kg d.w.). Mean accumulation of U in C. dilutus larvae decreased significantly from 1195 to 10 mg U/kg d.w. as kaolin clay content increased from 0% to 60% in sediment spiked with 50 mg U/kg d.w. Similarly, higher organic matter content also resulted in a significant reduction of U bioaccumulation in C. dilutus larvae, indicating a reduction in U bioavailability. Concentrations of U in both the overlying water and sediment pore water displayed a strong positive relationship to U bioaccumulation in C. dilutus larvae (r(2) = 0.77, p<0.001 and r(2) = 0.57, p < 0.001, respectively) for all experiments, while total U concentrations in the sediment had a poor relationship to U bioaccumulation (r(2) = 0.10, p = 0.028). Results from this research confirm that sediment clay and organic matter content play a significant role in altering U bioavailability, which is important in informing risk assessments of U contaminated sites and in the development of site-specific sediment quality guidelines for U.

  10. Toxicity of sediments from lead-zinc mining areas to juvenile freshwater mussels (Lampsilis siliquoidea) compared to standard test organisms.

    PubMed

    Besser, John M; Ingersoll, Christopher G; Brumbaugh, William G; Kemble, Nile E; May, Thomas W; Wang, Ning; MacDonald, Donald D; Roberts, Andrew D

    2015-03-01

    Sediment toxicity tests compared chronic effects on survival, growth, and biomass of juvenile freshwater mussels (28-d exposures with Lampsilis siliquoidea) to the responses of standard test organisms-amphipods (28-d exposures with Hyalella azteca) and midges (10-d exposures with Chironomus dilutus)-in sediments from 2 lead-zinc mining areas: the Tri-State Mining District and Southeast Missouri Mining District. Mussel tests were conducted in sediments sieved to <0.25 mm to facilitate recovery of juvenile mussels (2-4 mo old). Sediments were contaminated primarily with lead, zinc, and cadmium, with greater zinc and cadmium concentrations in Tri-State sediments and greater lead concentrations in southeast Missouri sediments. The frequency of highly toxic responses (reduced 10% or more relative to reference sites) in Tri-State sediments was greatest for amphipod survival (25% of samples), midge biomass (20%), and mussel survival (14%). In southeast Missouri sediments, the frequency of highly toxic samples was greatest for mussel biomass (25%) and amphipod biomass (13%). Thresholds for metal toxicity to mussels, expressed as hazard quotients based on probable effect concentrations, were lower for southeast Missouri sediments than for Tri-State sediments. Southeast Missouri sites with toxic sediments had 2 or fewer live mussel taxa in a concurrent mussel population survey, compared with 7 to 26 taxa at reference sites. These results demonstrate that sediment toxicity tests with juvenile mussels can be conducted reliably by modifying existing standard methods; that the sensitivity of mussels to metals can be similar to or greater than standard test organisms; and that responses of mussels in laboratory toxicity tests are consistent with effects on wild mussel populations.

  11. Toxicity of sediments from lead-zinc mining areas to juvenile freshwater mussels (Lampsilis siliquoidea) compared to standard test organisms

    USGS Publications Warehouse

    Besser, John M.; Ingersoll, Christopher G.; Brumbaugh, William G.; Kemble, Nile E.; May, Thomas W.; Wang, Ning; MacDonald, Donald D.; Roberts, Andrew D.

    2015-01-01

    Sediment toxicity tests compared chronic effects on survival, growth, and biomass of juvenile freshwater mussels (28-d exposures with Lampsilis siliquoidea) to the responses of standard test organisms—amphipods (28-d exposures with Hyalella azteca) and midges (10-d exposures with Chironomus dilutus)—in sediments from 2 lead–zinc mining areas: the Tri-State Mining District and Southeast Missouri Mining District. Mussel tests were conducted in sediments sieved to <0.25 mm to facilitate recovery of juvenile mussels (2–4 mo old). Sediments were contaminated primarily with lead, zinc, and cadmium, with greater zinc and cadmium concentrations in Tri-State sediments and greater lead concentrations in southeast Missouri sediments. The frequency of highly toxic responses (reduced 10% or more relative to reference sites) in Tri-State sediments was greatest for amphipod survival (25% of samples), midge biomass (20%), and mussel survival (14%). In southeast Missouri sediments, the frequency of highly toxic samples was greatest for mussel biomass (25%) and amphipod biomass (13%). Thresholds for metal toxicity to mussels, expressed as hazard quotients based on probable effect concentrations, were lower for southeast Missouri sediments than for Tri-State sediments. Southeast Missouri sites with toxic sediments had 2 or fewer live mussel taxa in a concurrent mussel population survey, compared with 7 to 26 taxa at reference sites. These results demonstrate that sediment toxicity tests with juvenile mussels can be conducted reliably by modifying existing standard methods; that the sensitivity of mussels to metals can be similar to or greater than standard test organisms; and that responses of mussels in laboratory toxicity tests are consistent with effects on wild mussel populations.

  12. Storage and source of polycyclic aromatic hydrocarbons in sediments downstream of a major coal district in France.

    PubMed

    Bertrand, O; Mondamert, L; Grosbois, C; Dhivert, E; Bourrain, X; Labanowski, J; Desmet, M

    2015-12-01

    During the 20th century, the local economy of the Upper Loire Basin (ULB) was essentially based on industrial coal mining extraction. One of the major French coal districts with associated urban/industrial activities and numerous coking/gas plants were developed in the Ondaine-Furan subbasins, two tributaries of the upper Loire main stream. To determine the compositional assemblage, the level and the potential sources of contamination, the historical sedimentary chronicle of the 16 US EPA priority polycyclic aromatic hydrocarbons (PAHs) has been investigated. PAH concentrations were determined using gas chromatography/mass spectrometry (GC/MS) in a dated core, sampled in the Villerest flood-control reservoir located downstream of the Ondaine-Furan corridor (OFC). The most contaminated sediments were deposited prior to 1983 (Σ16PAHs ca. 4429-13,348 ng/g) and during flood events (Σ16PAHs ca. 6380 ng/g - 1996 flood; 5360 ng/g - 2003 flood; 6075 ng/g - 2008 flood), especially in medium and high molecular weight PAHs. Among them, typical pyrogenic PAHs such as FLT, PYR, BbF and BaP were prevalent in most of the core samples. In addition, some PAHs last decade data is available from the Loire Bretagne Water Agency and were analyzed using high-performance liquid chromatography with postcolumn fluorescence derivatization (HPLC/FLD). These results confirm that the most highly contaminated sediments were found downstream of OFC (Σ16PAHs ca. 2264-7460 ng/g). According to the observed molecular distribution, PAHs are originated largely from high-temperature pyrolytic processes. Major sources of pyrogenic PAHs have been emphasized by calculation of specific ratios and by comparison to reported data. Atmospheric deposition of urban and industrial areas, wood combustion and degraded coal tar derived from former factories of coking/gas plants seem to be the major pyrogenic sources. Specifically, particular solid transport conditions that can occur during major flood

  13. Storage and source of polycyclic aromatic hydrocarbons in sediments downstream of a major coal district in France.

    PubMed

    Bertrand, O; Mondamert, L; Grosbois, C; Dhivert, E; Bourrain, X; Labanowski, J; Desmet, M

    2015-12-01

    During the 20th century, the local economy of the Upper Loire Basin (ULB) was essentially based on industrial coal mining extraction. One of the major French coal districts with associated urban/industrial activities and numerous coking/gas plants were developed in the Ondaine-Furan subbasins, two tributaries of the upper Loire main stream. To determine the compositional assemblage, the level and the potential sources of contamination, the historical sedimentary chronicle of the 16 US EPA priority polycyclic aromatic hydrocarbons (PAHs) has been investigated. PAH concentrations were determined using gas chromatography/mass spectrometry (GC/MS) in a dated core, sampled in the Villerest flood-control reservoir located downstream of the Ondaine-Furan corridor (OFC). The most contaminated sediments were deposited prior to 1983 (Σ16PAHs ca. 4429-13,348 ng/g) and during flood events (Σ16PAHs ca. 6380 ng/g - 1996 flood; 5360 ng/g - 2003 flood; 6075 ng/g - 2008 flood), especially in medium and high molecular weight PAHs. Among them, typical pyrogenic PAHs such as FLT, PYR, BbF and BaP were prevalent in most of the core samples. In addition, some PAHs last decade data is available from the Loire Bretagne Water Agency and were analyzed using high-performance liquid chromatography with postcolumn fluorescence derivatization (HPLC/FLD). These results confirm that the most highly contaminated sediments were found downstream of OFC (Σ16PAHs ca. 2264-7460 ng/g). According to the observed molecular distribution, PAHs are originated largely from high-temperature pyrolytic processes. Major sources of pyrogenic PAHs have been emphasized by calculation of specific ratios and by comparison to reported data. Atmospheric deposition of urban and industrial areas, wood combustion and degraded coal tar derived from former factories of coking/gas plants seem to be the major pyrogenic sources. Specifically, particular solid transport conditions that can occur during major flood

  14. Evaluation of freshwater sediment quality values including apparent effects thresholds of Hyalella azteca and Microtox{reg_sign}

    SciTech Connect

    Cubbage, J.; Batts, D.

    1995-12-31

    Data from 36 studies in Washington State were merged into a single database to derive Apparent Effects Thresholds (AETS) for freshwater sediments and to evaluate other sediment quality values. Sediments from 235 sites were analyzed for several contaminants, Bioassays tested at 30 or more of these sites included Hyalella azteca, Daphnia magna and Chironomus tentans mortality, Ceriodaphnia dubia reproduction and growth, and Microtox{reg_sign} luminescence reduction. Adequate sample size (n > 50) and wide range of response were available for Hyalella (n = 235) and Microtox{reg_sign} (n = 61) to determine AETs for organic carbon normalized PAHs, pesticides, and PCBs, and dry weight normalized metals, phenols and chlorinated phenols. The ability of these AETs to predict response in any bioassay at the sites in the database was compared with Ontario Ministry Environment and Energy (OMEE) Sediment Quality Guidelines and the Environment Canada (EC) Interim Sediment Quality Values. Measures of sensitivity (number correctly predicted/number impacted) and efficiency (number correctly predicted/number predicted) were compared. The EC Threshold Effects Level (TEL) was the most sensitive (fewest Type 2 errors) at 92%, but the least efficient (most Type 1 errors) at 35%. The lowest AET (LAET) of Hyalella and Microtox{reg_sign}, derived from the current study, was the next most sensitive (77%) and more efficient (44%). The OMEE Severe Effects Level was the least sensitive (59%) and the most efficient (53%). The EC Probable Effects Level (PEL) was 50% efficient and 72% sensitive. Of the four sets of sediment quality values, the OMEE Severe Effects Level had the highest overall reliability (number of correct predictions of effects and non-effects/number of sites examined) in predicting bioassay effects in the Washington State freshwater sediment database.

  15. Determination of Premining Geochemical Background and Delineation of Extent of Sediment Contamination in Blue Creek Downstream from Midnite Mine, Stevens County, Washington

    USGS Publications Warehouse

    Church, Stanley E.; Kirschner, Frederick E.; Choate, LaDonna M.; Lamothe, Paul J.; Budahn, James R.; Brown, Zoe Ann

    2008-01-01

    Geochemical and radionuclide studies of sediment recovered from eight core sites in the Blue Creek flood plain and Blue Creek delta downstream in Lake Roosevelt provided a stratigraphic geochemical record of the contamination from uranium mining at the Midnite Mine. Sediment recovered from cores in a wetland immediately downstream from the mine site as well as from sediment catchments in Blue Creek and from cores in the delta in Blue Creek cove provided sufficient data to determine the premining geochemical background for the Midnite Mine tributary drainage. These data provide a geochemical background that includes material eroded from the Midnite Mine site prior to mine development. Premining geochemical background for the Blue Creek basin has also been determined using stream-sediment samples from parts of the Blue Creek, Oyachen Creek, and Sand Creek drainage basins not immediately impacted by mining. Sediment geochemistry showed that premining uranium concentrations in the Midnite Mine tributary immediately downstream of the mine site were strongly elevated relative to the crustal abundance of uranium (2.3 ppm). Cesium-137 (137Cs) data and public records of production at the Midnite Mine site provided age control to document timelines in the sediment from the core immediately downstream from the mine site. Mining at the Midnite Mine site on the Spokane Indian Reservation between 1956 and 1981 resulted in production of more than 10 million pounds of U3O8. Contamination of the sediment by uranium during the mining period is documented from the Midnite Mine along a small tributary to the confluence of Blue Creek, in Blue Creek, and into the Blue Creek delta. During the period of active mining (1956?1981), enrichment of base metals in the sediment of Blue Creek delta was elevated by as much as 4 times the concentration of those same metals prior to mining. Cadmium concentrations were elevated by a factor of 10 and uranium by factors of 16 to 55 times premining

  16. Influence of allochtonous carbon input and food-web structure on freshwater biotic communities and sedimentation process

    NASA Astrophysics Data System (ADS)

    Harrault, Loïc; Allard, Béatrice; Mériguet, Jacques; Carmignac, David; Perret, Samuel; Huon, Sylvain; Edeline, Eric; Lacroix, Gérard

    2013-04-01

    Soil erosion in freshwaters induces important changes in lake metabolism. The organic matter and the nutrients supplied by soil inputs can change internal biogeochemical cycles and subsidize the whole food web from basal organisms to top-predators. Since the last two decades, the role of allochthonous organic matter as a basal resource for aquatic food webs in natural and controlled conditions has received a growing attention. We studied the impact of soil on the functioning of pond ecosystems by performing monthly additions of soil in freshwater mesocosms. In addition, the food-web structure was manipulated by addition of omnivorous fish to study interactions between the bottom-up effect of soil addition and the top-down effect of fish. The effects of soil and fish addition on the, the elemental and the biochemical compositions of pelagic compartments and recent sediment, on the biomass of seston and zooplankton and on the sediment rates were studied. Soil inputs had no effect on biomass, stoichiometry and lipid composition of seston and zooplankton but fish growth was enhanced by soil addition. Soil treatment had several (but idiosyncratic) effects on the stoichiometry and on the lipid composition of recent sediment. However, the sedimentation rates and the potential biodegradability of recent sediment were not affected by soil inputs. Fish addition affected chlorophyll-a concentration of the water column, seston biomass, sedimentation rates and stoichiometry of seston, zooplankton and short-term sediment. The lipid composition of recent sediment was also influenced by fish addition. However, fish addition did not change the biodegradability of recent sediment. Finally, we did not observe any significant interaction between soil and fish treatments. Our results suggest that the addition of soil as allochthonous inputs to aquatic ecosystem induced a subsidize of the food web only on fish, probably due to direct foraging on bottom sediment. Nevertheless, this

  17. Water and sediment toxicity of freshwater mussels from population crashes of Asiatic clams

    SciTech Connect

    Scheller, J.L.; Cherry, D.S.; Yeager, M.M.; Lynde, S.R.; Shepard, N.D.

    1994-12-31

    The Clinch River watershed in Virginia contains one of the most diverse communities of freshwater bivalves or unionids in North America. These communities are becoming depleted over the past few decades due to various point (industrial, municipal) and nonpoint (roadside and agricultural runoff) discharges. By the latter 1980`s, the Asiatic clam (Corbicula fluminea) had invaded most reaches of this system and may be becoming a contributing factor to the demise of native mussels by the natural release of toxic ammonia from dense population crashes during late summer, low flow conditions. When densities surpassed 1,500 clams/m{sup 2}, crashes resulting in >99% mortality have been observed in various areas of the river. Total ammonia release from dying clams reached and sustained 70 mg/L for several days in laboratory artificial stream experiments. These ammonia levels resulted in acute toxicity and reproductive chronic impairment to Daphnia magna in 10-day sediment toxicity tests. Pediveliger larvae of Corbicula were acutely sensitive (48 hr LC{sub 50}) to 1.72 mg/L total ammonia (O.05 mg/L unionized), mortality was 100% to juvenile and adult clams in 9 to 13 days at 16.1 mg/L total (0.74 mg/L unionized ammonia). Mussel glochidia were sensitive to 24-hr ammonia exposures (LC{sub 50} = 3.29 and 0.11 mg/L as total and unionized ammonia, respectively). Juvenile and adult mussels are predicted to be less sensitive members of the unionid life cycle as observed from earlier studies involving copper toxicity in the Clinch River.

  18. Hymenobacter latericoloratus sp. nov. and Hymenobacter luteus sp. nov., isolated from freshwater sediment.

    PubMed

    Liu, Lan; Zhou, En-Min; Jiao, Jian-Yu; Manikprabhu, Deene; Ming, Hong; Liu, Wei-Hong; Hozzein, Wael N; Shu, Wen-Sheng; Li, Wen-Jun

    2015-01-01

    Two novel Gram-stain negative, non-motile, rod-shaped and aerobic bacterial strains, designated YIM 77920(T) and YIM 77921(T), were isolated from freshwater sediment of Jiuxiang cave, a tourism cave located in Yiliang county, Yunnan province, south-west China. The 16S rRNA gene sequences of strains YIM 77920(T) and YIM 77921(T) exhibited sequence similarities of 96.59 and 96.66 % to Hymenobacter xinjiangensis X2-Y(T), respectively, and indicated that the two isolates belong to the genus Hymenobacter. The major fatty acids present in the two strains were identified as C16:1 ω5c, iso-C15:0 and Summed Feature 4 (C17:1 anteiso B/iso I). MK-7 was identified as the respiratory quinone component for both strains. The polar lipids profile of strain YIM 77920(T) was found to consist of phosphatidylethanolamine, four unidentified polar lipids, three unidentified aminophospholipids, two unidentified phospholipids and two unidentified aminolipids, while that of strain YIM 77921(T) consisted of phosphatidylethanolamine, four unidentified polar lipids, two unidentified aminolipids, one unidentified phospholipid and four unidentified aminophospholipids. The DNA G+C contents of strains YIM 77920(T) and YIM 77921(T) were determined to be 57.5 and 59.6 mol%, respectively. DNA-DNA hybridization between them had a low value (56.55 %). Based on the morphological and physiological properties, and phylogenetic analyses, strains YIM 77920(T) and YIM 77921(T) are considered to represent two novel species of the genus Hymenobacter, for which the names Hymenobacter latericoloratus sp. nov. (type strain YIM 77920(T) = JCM 30327(T) = CCTCC AB 2012949(T)) and Hymenobacter luteus sp. nov. (type strain YIM 77921(T) = JCM 30328(T) = CCTCC AB 2012947(T)) are proposed. PMID:25348876

  19. Seed dormancy and persistent sediment seed banks of ephemeral freshwater rock pools in the Australian monsoon tropics

    PubMed Central

    Cross, Adam T.; Turner, Shane R.; Renton, Michael; Baskin, Jerry M.; Dixon, Kingsley W.; Merritt, David J.

    2015-01-01

    Background and Aims Rock pools are small, geologically stable freshwater ecosystems that are both hydrologically and biologically isolated. They harbour high levels of plant endemism and experience environmental unpredictability driven by the presence of water over variable temporal scales. This study examined the hypothesis that the sediment seed bank in monsoon tropical freshwater rock pools would persist through one or more periods of desiccation, with seed dormancy regulating germination timing in response to rock pool inundation and drying events. Methods Seeds were collected from seven dominant rock pool species, and germination biology and seed dormancy were assessed under laboratory conditions in response to light, temperature and germination stimulators (gibberellic acid, karrikinolide and ethylene). Field surveys of seedling emergence from freshwater rock pools in the Kimberley region of Western Australia were undertaken, and sediment samples were collected from 41 vegetated rock pools. Seedling emergence and seed bank persistence in response to multiple wetting and drying cycles were determined. Key Results The sediment seed bank of individual rock pools was large (13 824 ± 307 to 218 320 ± 42 412 seeds m−2 for the five species investigated) and spatially variable. Seedling density for these same species in the field ranged from 13 696 to 87 232 seedlings m−2. Seeds of rock pool taxa were physiologically dormant, with germination promoted by after-ripening and exposure to ethylene or karrikinolide. Patterns of seedling emergence varied between species and were finely tuned to seasonal temperature and moisture conditions, with the proportions of emergent seedlings differing between species through multiple inundation events. A viable seed bank persisted after ten consecutive laboratory inundation events, and seeds retained viability in dry sediments for at least 3 years. Conclusions The persistent seed bank in freshwater rock pools is likely to

  20. Assessment of the use of the AVS concept for the routine toxicity monitoring of contaminated freshwater sediments

    SciTech Connect

    Vangheluwe, M.L.; Janssen, C.R.; Goyvaerts, M.P.; Cooman, P.

    1995-12-31

    Acid volatile sulfides (AVS) have been shown to be an important factor mediating the bioavailability of heavy metals in sediments and have consequently been suggested as a possible predictive tool for toxicity assessment of these matrices. The potential use and limitations of the AVS method for predictive toxicity screening and priority setting was assessed in a large scale sediment monitoring study (Flanders, Belgium). The acute toxicity of 50 metal contaminated freshwater sediments, with varying metal concentrations and sediment characteristics, were tested using the Microtox{reg_sign} Solid Phase test and the 10 day test with Chironomus riparius and Hyalella azteca. Uni and multivariate statistical techniques were used to asses the relations between acute toxicity and SEM/AVS ratio`s and to evaluate the influence of sediment characteristics on metal bioavailability and toxicity. In general, the results of this study indicate that the AVS-toxicity relationship proposed in literature does have certain limitations. Finally, the potential use of a concentration-addition model for predicting metal-mixture toxicity in sediments will be presented and discussed.

  1. Benthic flagellates and ciliates in fine freshwater sediments: Calibration of a live counting procedure and estimation of their abundances.

    PubMed

    Gasol, J M

    1993-05-01

    Despite the recognized importance of protozoans (flagellates and ciliates) as predators of bacteria, there are very few estimates of their abundance in fine sediments of freshwater lakes. This is due, in part, to the lack of a standard methodology. Because of the low concentration of protists in relation to particles, epifluorescence counts can not always be used. Instead, dilution followed by live counting was used to solve the masking by sediment particles. One to twenty μ1 sample aliquots were diluted with filtered lake water in a Palmer-Maloney counting slide. Four to eight replicates were sufficient to minimize the counting error, while minimizing effort. The method is highly replicable and could potentially be calibrated for different sediment types because sediment masking depends on the mean particle size of the sediment. When this method was applied in a survey of benthic sites in Quebec lakes, flagellate abundances were found to range from 100 to 180,000 cells ml(-1), while ciliate numbers ranged from 26 to 11,000 cells ml(-1). Bacteria are 105 to 10(7) times more abundant than protists and, thus, the impact of these protists on sediment bacterial dynamics is likely to be minimal.

  2. Wastewater as a point source of antibiotic-resistance genes in the sediment of a freshwater lake

    PubMed Central

    Czekalski, Nadine; Gascón Díez, Elena; Bürgmann, Helmut

    2014-01-01

    Antibiotic-resistance genes (ARGs) are currently discussed as emerging environmental contaminants. Hospital and municipal sewage are important sources of ARGs for the receiving freshwater bodies. We investigated the spatial distribution of different ARGs (sul1, sul2, tet(B), tet(M), tet(W) and qnrA) in freshwater lake sediments in the vicinity of a point source of treated wastewater. ARG contamination of Vidy Bay, Lake Geneva, Switzerland was quantified using real-time PCR and compared with total mercury (THg), a frequently particle-bound inorganic contaminant with known natural background levels. Two-dimensional mapping of the investigated contaminants in lake sediments with geostatistical tools revealed total and relative abundance of ARGs in close proximity of the sewage discharge point were up to 200-fold above levels measured at a remote reference site (center of the lake) and decreased exponentially with distance. Similar trends were observed in the spatial distribution of different ARGs, whereas distributions of ARGs and THg were only moderately correlated, indicating differences in the transport and fate of these pollutants or additional sources of ARG contamination. The spatial pattern of ARG contamination and supporting data suggest that deposition of particle-associated wastewater bacteria rather than co-selection by, for example, heavy metals was the main cause of sediment ARG contamination. PMID:24599073

  3. Laboratory culture of the freshwater benthic gastropod Bellamya aeruginosa (Reeve) and its utility as a test species for sediment toxicity.

    PubMed

    Ma, Taowu; Gong, Shuangjiao; Zhou, Ke; Zhu, Cheng; Deng, Kaidong; Luo, Qinghua; Wang, Zijian

    2010-01-01

    This study aimed to develop original laboratory culture and sediment toxicity testing protocols for the freshwater gastropod Bellamya aeruginosa (Reeve), a new potential species for sediment toxicity testing. B. aeruginosa was successfully cultured with an effective culture system under proposed laboratory conditions. Optimal ad libitum feeding levels for larvae, juveniles, and adults were 2.0, 6.0, and 16.0 mg fish food/(snail x day), respectively. Mean survival rates of juveniles were higher than 90%. The snails could be sexed at 9 weeks of age, and their generation time is approximately 4 months. Reproduction continued all year around; the mean fecundity was 0.55 newborn/(female x day). The utility of this species for bioassays was evaluated in both 10-day and 28-day case studies with artificial sediments. The 10-day LC50 of Cu for larvae was 480 gg/g dry weight (dw), and the lowest observed effects concentration of Cu for survival and growth of larvae was 195 microg/g dw. Survival and growth are reliable indicators of acute toxicity. Larvae accumulated more Cu than adults. B. aeruginosa exhibited a higher sensitivity to Cu exposure than standard test species (Hyalella azteca and Chironomus tentans). The 28-day test of sediment toxicity with adults showed that fecundity was a robust endpoint indicator of reproductive toxicity, and the biochemical endpoints of superoxide dismutase, catalase, and glutathione could be used as sensitive biomarkers for Cu-induced oxidative damage. B. aeruginosa can be therefore recommended as a candidate for the standardization of the freshwater sediment toxicity test protocol.

  4. Chironomus plumosus larvae increase fluxes of denitrification products and diversity of nitrate-reducing bacteria in freshwater sediment.

    PubMed

    Poulsen, Morten; Kofoed, Michael V W; Larsen, Lone H; Schramm, Andreas; Stief, Peter

    2014-02-01

    Benthic invertebrates affect microbial processes and communities in freshwater sediment by enhancing sediment-water solute fluxes and by grazing on bacteria. Using microcosms, the effects of larvae of the widespread midge Chironomus plumosus on the efflux of denitrification products (N2O and N2+N2O) and the diversity and abundance of nitrate- and nitrous-oxide-reducing bacteria were investigated. Additionally, the diversity of actively nitrate- and nitrous-oxide-reducing bacteria was analyzed in the larval gut. The presence of larvae increased the total effluxes of N2O and N2+N2O up to 8.6- and 4.2-fold, respectively, which was mostly due to stimulation of sedimentary denitrification; incomplete denitrification in the guts accounted for up to 20% of the N2O efflux. Phylotype richness of the nitrate reductase gene narG was significantly higher in sediment with than without larvae. In the gut, 47 narG phylotypes were found expressed, which may contribute to higher phylotype richness in colonized sediment. In contrast, phylotype richness of the nitrous oxide reductase gene nosZ was unaffected by the presence of larvae and very few nosZ phylotypes were expressed in the gut. Gene abundance of neither narG, nor nosZ was different in sediments with and without larvae. Hence, C. plumosus increases activity and diversity, but not overall abundance of nitrate-reducing bacteria, probably by providing additional ecological niches in its burrow and gut.

  5. The use of an aeration system to prevent thermal stratification of a freshwater impoundment and its effect on downstream fish assemblages.

    PubMed

    Miles, N G; West, R J

    2011-03-01

    Warm-water riverine fish assemblages were investigated downstream of an impoundment before and after thermal stratification and the associated cold-water pollution was prevented using an aeration system. Temperatures below the dam significantly increased after installation of the aeration system and this correlated with an increased abundance and greater number of species downstream. Overall, aeration appeared to be beneficial for both the lake (upstream) and the downstream riverine environments.

  6. The role of river sediments in contamination storage downstream of a waste water treatment plant in low flow conditions: Organotins, faecal indicator bacteria and nutrients

    NASA Astrophysics Data System (ADS)

    Chahinian, N.; Bancon-Montigny, C.; Caro, A.; Got, P.; Perrin, J. L.; Rosain, D.; Rodier, C.; Picot, B.; Tournoud, M. G.

    2012-12-01

    In intermittent rivers, characterised by a specific hydrological behaviour, sediment-water column interactions may influence water quality during low flows. The main objective of this work was to assess the extent of anthropogenic pollution (organotins, faecal indicator bacteria and nutrients) in the river sediment of an intermittent river and its impact on the downstream water bodies: The Vène River, main tributary of the Thau lagoon. We first investigated anthropogenic pollution from water and sediment samples collected in situ along the river course (1.5 km); then, during laboratory experiments, we assessed the survival of faecal bacteria and quantified the degradation rates of organotins on the same sediments. The results indicate the presence of anthropogenic pollution all along the study reach. The waste water treatment plant effluent is a direct pollution input source for anthropogenic pollution. The sediment data points to an urban drainage ditch as a secondary point pollution source while the organotins data highlights the presence of other diffuse sources, specific to this substance. The results of the laboratory experiments show that both faecal bacteria and organotins may persist in the river sediments for up to two months in summer and even longer in winter. This indicates that sediments may, under favourable conditions, become important pollutant stores which may later be released and transported to the Thau lagoon during floods.

  7. Behavior of osmium at the freshwater-saltwater interface based on Ganga derived sediments from the estuarine zone

    NASA Astrophysics Data System (ADS)

    Paul, M.; Reisberg, L.; Vigier, N.; France-Lanord, C.

    2011-12-01

    Leaching experiments performed on several sediments of the Ganga river suggest that between 10 and 20% of the osmium is in an easily exchangeable position. Analyses of sediments from two estuarine rivers (the Pussur and the lower Meghna) reveal no enrichment of Os in the saltwater-freshwater mixing zone relative to Ganga sediments of similar Al2O3/SiO2 ratio, suggesting that osmium is not significantly trapped in this estuary. However, a significant decrease of the 187Os/188Os ratio is observed in the Pussur sediments relative to the Ganga composition. These latter are derived entirely from the Ganga or from erosion of the Ganga paleodelta, and thus would be expected to have similar Os isotopic compositions. Nd isotopic results from the Pussur are indistinguishable from those of the Ganga, while the Sr isotopic results are at the lower end of the Ganga range, confirming the absence of a major source difference between Ganga and Pussur sediments. It thus seems unlikely that the difference in Os isotopic signature can be entirely explained by a change in provenance, suggesting instead that the Os compositions have been modified. Our results show that the less radiogenic Os compositions of the Pussur sediments cannot result simply from desorption of radiogenic Os or from scavenging of river or seawater Os. Instead, the decrease of the 187Os/188Os ratio could imply a complex exchange between dissolved Os, derived partly from seawater, and Os in the leachable fraction of sediments. This mechanism could therefore constitute both a source and a sink for seawater osmium and may significantly influence the osmium marine budget.

  8. GC-MS method for determining faecal sterols as biomarkers of human and pastoral animal presence in freshwater sediments.

    PubMed

    Battistel, Dario; Piazza, Rossano; Argiriadis, Elena; Marchiori, Enrico; Radaelli, Marta; Barbante, Carlo

    2015-11-01

    In order to determine sterols and stanols in freshwater sediments to reconstruct the past presence of humans and pastoral animals, we developed an analytical method based on pressurised liquid extraction (PLE), clean-up performed using solid phase extraction (SPE) and sterol determination using gas chromatography-mass spectrometry (GC-MS) analysis. PLE extraction conditions were optimised using dichloromethane (DCM) and DCM/methanol mixtures. Clean-up was performed with 2 g silica SPE cartridges, and the concentrated extracts were eluted with 70 mL DCM. Extraction yield was evaluated using an in-house reference material spiked with (13)C-labelled cholesterol and aged for 10 days. In comparison with pre-extraction, where the sediment is extracted and then spiked with a known analyte concentration, this approach preserves the original composition of the sediment. DCM and DCM/methanol mixtures resulted in high extraction yields ranging from 86 to 92 % with good reproducibility (relative standard deviation (RSD) 5-8 %). PLE extraction yields obtained with DCM as the extracting solvent were about 1.5 times higher than extractions using an ultrasonic bath. The solvent extraction mixture and matrix composition strongly affected the solvent extraction composition where higher overall recoveries (70-80 %) for each compound were obtained with DCM. The extraction mixture and matrix composition also affected the analyte concentrations, resulting in a method precision ranging from 1 to 18 %. Diatomaceous earth spiked with 10 to 100 ng of sterols, and environmental samples fortified with suitable amounts of sterols provided apparent recovery values ranging from 90 to 110 %. We applied the method to environmental samples both close to and upstream from sewage discharge zones, resulting in substantially higher faecal sterol (FeSt) concentrations near the sewage. In addition, we also applied the method to a 37-cm freshwater sediment core in order to evaluate its applicability for

  9. GC-MS method for determining faecal sterols as biomarkers of human and pastoral animal presence in freshwater sediments.

    PubMed

    Battistel, Dario; Piazza, Rossano; Argiriadis, Elena; Marchiori, Enrico; Radaelli, Marta; Barbante, Carlo

    2015-11-01

    In order to determine sterols and stanols in freshwater sediments to reconstruct the past presence of humans and pastoral animals, we developed an analytical method based on pressurised liquid extraction (PLE), clean-up performed using solid phase extraction (SPE) and sterol determination using gas chromatography-mass spectrometry (GC-MS) analysis. PLE extraction conditions were optimised using dichloromethane (DCM) and DCM/methanol mixtures. Clean-up was performed with 2 g silica SPE cartridges, and the concentrated extracts were eluted with 70 mL DCM. Extraction yield was evaluated using an in-house reference material spiked with (13)C-labelled cholesterol and aged for 10 days. In comparison with pre-extraction, where the sediment is extracted and then spiked with a known analyte concentration, this approach preserves the original composition of the sediment. DCM and DCM/methanol mixtures resulted in high extraction yields ranging from 86 to 92 % with good reproducibility (relative standard deviation (RSD) 5-8 %). PLE extraction yields obtained with DCM as the extracting solvent were about 1.5 times higher than extractions using an ultrasonic bath. The solvent extraction mixture and matrix composition strongly affected the solvent extraction composition where higher overall recoveries (70-80 %) for each compound were obtained with DCM. The extraction mixture and matrix composition also affected the analyte concentrations, resulting in a method precision ranging from 1 to 18 %. Diatomaceous earth spiked with 10 to 100 ng of sterols, and environmental samples fortified with suitable amounts of sterols provided apparent recovery values ranging from 90 to 110 %. We applied the method to environmental samples both close to and upstream from sewage discharge zones, resulting in substantially higher faecal sterol (FeSt) concentrations near the sewage. In addition, we also applied the method to a 37-cm freshwater sediment core in order to evaluate its applicability for

  10. Evaluation of the Reference Envelope Approach for Assessing Toxicity in Contaminated Surficial Urban Freshwater Sediments

    EPA Science Inventory

    The reference envelope (RE) has been proposed as an alternative approach to assess sediment toxicity to overcome limitations imposed by the use of control sediments including differences in non-contaminant characteristics and low statistical power when many test sediments are com...

  11. Glacial freshwater discharge events recorded by authigenic neodymium isotopes in sediments from the Mendeleev Ridge, western Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Jang, Kwangchul; Han, Yeongcheol; Huh, Youngsook; Nam, Seung-Il; Stein, Ruediger; Mackensen, Andreas; Matthiessen, Jens

    2013-05-01

    The freshwater budget of the Arctic Ocean is a key component governing the deep water formation in the North Atlantic and the global climate system. We analyzed the isotopic composition of neodymium (ɛNd) in authigenic phases of marine sediments on the Mendeleev Ridge in the western Arctic Ocean spanning an estimated time interval from present to about 75 ka BP. This continuous record was used to reconstruct the ɛNd of the polar deep water (PDW) and changes in freshwater sources to the PDW through time. Three deviations in ɛNd from a long term average of -10.2 were identified at estimated 46-51, 35-39 and 13-21 ka BP. The estimated 46-51 ka BP event can be traced to bursting of ice-dammed lakes accompanying the collapse of the Barents-Kara Ice Sheet, which would have released radiogenic Nd to the eastern Arctic Ocean. The cyclonic surface circulation in the eastern Arctic Ocean must have been stronger than at present for the event to be recorded on the Mendeleev Ridge. For the 35-39 and 13-21 ka BP events, it is likely that the Laurentide Ice Sheet (LIS) supplied the unradiogenic freshwater. The configuration of the anticyclonic circulation in the western Arctic was probably similar to today or expanded eastward. Our simple mass balance calculations suggest that large amounts of freshwater were released but due to significant deep water formation within the Arctic Ocean, the effect on the formation of NADW was probably minor.

  12. Responses of Hyalella azteca and Chironomus tentans to particle-size distribution and organic matter content of formulated and natural freshwater sediments

    SciTech Connect

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

    1994-10-01

    The freshwater amphipod, Hyalella azteca (Saussure), and midge, Chironomus tentans (Fabricius), were exposed to formulated sediments and nontoxic field-collected sediments for 10 d to determine their responses to varying sediment particle sizes and organic matter content of freshwater sediments. In experiments with formulated sediments, H. azteca survival was >80% when exposed for 10 d to all particle-size regimes examined. Subsequent exposures of H. azteca to field-collected sediments resulted in >80% H. azteca survival in all sediments. Field-collected sediments with organic matter content ranging from 0.12 to 7.8% yielded no observed effects on amphipod survival, which ranged from 84 to 100%. Survival of C. tentans ranged from 4 to 56% when exposed to formulated sediments for 10 d with 0% particulate organic matter content. A threshold organic matter content between 0.76 and 0.91% was observed for C. tentans exposed to formulated and field-collected sediments. Chironomus tentans survival was >80% in all cases when exposed to various particle-size regimes in formulated sediments containing 2.5% particulate organic matter. Formulated sediments were suitable for determining H. azteca and C. tentans responses to particle-size regimes and organic matter content of sediments, as test results using formulated and natural sediments were in agreement. Except for C. tentans observed intolerance of <0.76 to 0.91% organic matter content of sediments, C. tentans and H. azteca are suitable benthic toxicity testing organisms for determining the potential toxicity of sediments with a wide range of particle-size regimes and organic matter content.

  13. Seasonal variations in the concentrations of selected heavy metals and radionuclides in Sava River sediments upstream and downstream of NPP Krsko

    NASA Astrophysics Data System (ADS)

    Orescanin, Visnja; Mikelic, Luka; Lulic, Stipe; Pavlovic, Gordana; Coumbassa, Nana

    2007-10-01

    In order to estimate the influence of a nuclear power plant and other industrial and agricultural anthropogenic sources on the quality of Sava River sediments, samples taken from seven locations (one upstream and six downstream of the Krsko NPP) were characterized. Seasonal variations in the sediment composition were determined on the basis of four samplings taken during the year 2004 (in February, May, October and December). Total concentrations of the elements Cr, Mn, Fe, Cu, Zn, Co and Pb in the sediment fractions less than 0.5 mm have been measured by source excited energy dispersive X-ray fluorescence (EDXRF), while 40K, 137Cs, 131I, 7Be, 228Th, Th(228Ra), U(234Th), 226Ra and 210Pb were determined by gamma spectrometry. Mineralogical examinations of the samples were performed using the X-ray diffraction (XRD) method.

  14. Superfund record of decision (EPA Region 1): New London Submarine Base, soil and sediment at Area A Downstream Water Courses/Overbank Disposal Area, Groton, CT, March 31, 1998

    SciTech Connect

    1998-09-01

    Area A Downstream Water Courses/Overbank Disposal Area (Area A Downstream/OBDA) is located on the Naval Submarine Base New London (NSB-NLON), Groton, Connecticut. This Record of Decision (ROD) addresses the contaminated soil and sediment at this site. This ROD presents the following final remedy for soil and sediment at Area A Downstream/OBDA: Removal of surface water followed by treatment and discharge to Thames River; and Excavation of contaminated soil and sediment, followed by onsite dewatering and disposal at an offsite landfill.

  15. Selective pressure of antibiotics on ARGs and bacterial communities in manure-polluted freshwater-sediment microcosms

    PubMed Central

    Xiong, Wenguang; Sun, Yongxue; Ding, Xueyao; Wang, Mianzhi; Zeng, Zhenling

    2015-01-01

    The aim of this study was to investigate selective pressure of antibiotics on antibiotic resistance genes (ARGs) and bacterial communities in manure-polluted aquatic environment. Three treatment groups were set up in freshwater-sediment microcosms: tetracyclines group, sulfonamides group and fluoroquinolones group. Sediment and water samples were collected on day 14 after treatment. Antibiotic concentrations, ARGs abundances and bacterial community composition were analyzed. Antibiotic concentrations were determined by ultra-performance liquid chromatography-electrospray tandem mass spectrometry. ARGs abundances were quantified by real time quantitative PCR. Bacterial community composition was analyzed based on amplicon sequencing. Of the three classes of antibiotics analyzed in the treatment groups, accumulation amounts were tetracyclines> fluoroquinolone> sulfonamides in the sediment samples, while they were sulfonamides> fluoroquinolone> tetracyclines in the water samples. In the treatment groups, the relative abundances of some tet resistance genes [tet(W) and tet(X)] and plasmid-mediated quinolone resistance (PMQR) genes [oqx(B) and aac(6′)-Ib] in sediment samples were significantly higher than those in the paired water samples. Tetracyclines significantly selected the bacterial classes including Gammaproteobacteria, Clostridia, and the genera including Salmonella, Escherichia/Shigella, Clostridium, Stenotrophomonas in sediment samples. The significant selection on bacterial communities posed by sulfonamides and fluoroquinolones was also observed. The results indicated that sediment may supply an ideal setting for maintenance and persistence of tet resistance genes [tet(W) and tet(X)] and PMQR genes [oqx(B) and aac(6′)-Ib] under antibiotic pollution. The results also highlighted that antibiotics significantly selected specific bacterial communities including the taxa associated with opportunistic pathogens. PMID:25814986

  16. Factors influencing mercury in freshwater surface sediments of northeastern North America

    USGS Publications Warehouse

    Kamman, N.C.; Chalmers, A.; Clair, T.A.; Major, A.; Moore, R.B.; Norton, S.A.; Shanley, J.B.

    2005-01-01

    We report on an inventory and analysis of sediment mercury (Hg) concentrations from 579 sites across northeastern North America. Sediment Hg concentrations ranged from the limit of detection ca. 0.01-3.7 ??g g -1 (dry weight, d.w.), and the average concentration was 0.19 ??g g-1 (d.w.) Sediment methylmercury concentrations ranged from 0.15 to 21 ng g-1 (d.w.) and the mean concentration was 3.83 ng g -1 (d.w.). Total Hg concentrations (HgT) were greatest in lakes > reservoirs > rivers, although the proportion of Hg as methylmercury showed an inverse pattern. Total Hg was weakly and positively correlated with the sediment organic matter and percent of watershed as forested land, and weakly and negatively correlated with sediment solids content, drainage area, and agricultural land. Sediment methylmercury concentrations were weakly and positively correlated to wetland area, and weakly and negatively correlated to drainage area. Methylmercury, expressed as a percentage of HgT was positively correlated to agricultural land area. For sites with co-located sediment and fish-tissue sampling results, there was no relationship between sediment Hg and fish-tissue Hg. Finally, our data indicate that at least 44% of waters across the region have sediment HgT concentrations in excess of Canadian and United States minimum sediment contaminant guidelines for the protection of aquatic biota. ?? 2005 Springer Science+Business Media, Inc.

  17. Microbial diversity and community respiration in freshwater sediments influenced by artificial light at night

    PubMed Central

    Hölker, Franz; Wurzbacher, Christian; Weißenborn, Carsten; Monaghan, Michael T.; Holzhauer, Stephanie I. J.; Premke, Katrin

    2015-01-01

    An increasing proportion of the Earth's surface is illuminated at night. In aquatic ecosystems, artificial light at night (ALAN) may influence microbial communities living in the sediments. These communities are highly diverse and play an important role in the global carbon cycle. We combined field and laboratory experiments using sediments from an agricultural drainage system to examine how ALAN affects communities and alters carbon mineralization. Two identical light infrastructures were installed parallel to a drainage ditch before the start of the experiment. DNA metabarcoding indicated that both sediment communities were similar. After one was lit for five months (July–December 2012) we observed an increase in photoautotroph abundance (diatoms, Cyanobacteria) in ALAN-exposed sediments. In laboratory incubations mimicking summer and winter (six weeks each), communities in sediments that were exposed to ALAN for 1 year (July 2012–June 2013) showed less overall seasonal change compared with ALAN-naive sediments. Nocturnal community respiration was reduced in ALAN-exposed sediments. In long-term exposed summer-sediments, we observed a shift from negative to positive net ecosystem production. Our results indicate ALAN may alter sediment microbial communities over time, with implications for ecosystem-level functions. It may thus have the potential to transform inland waters to nocturnal carbon sinks. PMID:25780242

  18. Depositional influences on porewater arsenic in sediments of a mining-contaminated freshwater lake.

    PubMed

    Toevs, Gordon; Morra, Matthew J; Winowiecki, Leigh; Strawn, Daniel; Polizzotto, Matthew L; Fendorf, Scott

    2008-09-15

    Arsenic-containing minerals mobilized during mining activities and deposited to Lake Coeur d'Alene (CDA), Idaho sediments represent a potential source of soluble As to the overlying water. Our objective was to delineate the processes controlling porewater As concentrations within Lake CDA sediments. Sediment and porewater As concentrations were determined, and solid-phase As associations were probed using X-ray absorption near-edge structure (XANES) spectroscopy. Although maximum As in the sediment porewaters varied from 8.4 to 16.2 microM, As sorption on iron oxyhydroxides at the oxic sediment-water interface prevented flux to overlying water. Floods deposit sediment containing variable amounts of arsenopyrite (FeAsS), with majorfloods depositing large amounts of sediment that bury and preserve reduced minerals. Periods of lower deposition increase sediment residence times in the oxic zone, promoting oxidation of reduced minerals, SO4(2-) efflux, and formation of oxide precipitates. Depositional events bury oxides containing sorbed As, transitioning them into anoxic environments where they undergo dissolution, releasing As to the porewater. High Fe:S ratios limit the formation of arsenic sulfides in the anoxic zone. As a result of As sequestration at the sediment-water interface and its release upon burial, decreased concentrations of porewater As will not occur unless As-bearing erosional inputs are eliminated.

  19. Depositional Influences on Porewater Arsenic in Sediments of a Mining-Contaminated Freshwater Lake

    SciTech Connect

    Toevs, G.; Morra, M.J.; Winowiecki, L.; Strawn, D.; Polizzotto, M.L.; Fendorf, S.

    2009-05-26

    Arsenic-containing minerals mobilized during mining activities and deposited to Lake Coeur d'Alene (CDA), Idaho sediments represent a potential source of soluble As to the overlying water. Our objective was to delineate the processes controlling porewater As concentrations within Lake CDA sediments. Sediment and porewater As concentrations were determined, and solid-phase As associations were probed using X-ray absorption near-edge structure (XANES) spectroscopy. Although maximum As in the sediment porewaters varied from 8.4 to 16.2 microM, As sorption on iron oxyhydroxides at the oxic sediment-water interface prevented flux to overlying water. Floods deposit sediment containing variable amounts of arsenopyrite (FeAsS), with majorfloods depositing large amounts of sediment that bury and preserve reduced minerals. Periods of lower deposition increase sediment residence times in the oxic zone, promoting oxidation of reduced minerals, SO4(2-) efflux, and formation of oxide precipitates. Depositional events bury oxides containing sorbed As, transitioning them into anoxic environments where they undergo dissolution, releasing As to the porewater. High Fe:S ratios limit the formation of arsenic sulfides in the anoxic zone. As a result of As sequestration at the sediment-water interface and its release upon burial, decreased concentrations of porewater As will not occur unless As-bearing erosional inputs are eliminated.

  20. The impact of the Three Gorges Dam on the downstream distribution and texture of sediments along the middle and lower Yangtze River (Changjiang) and its estuary, and subsequent sediment dispersal in the East China Sea

    NASA Astrophysics Data System (ADS)

    Luo, X. X.; Yang, S. L.; Zhang, J.

    2012-12-01

    The grain size of river sediments changes systematically downstream from source to sink, and is influenced by catchment lithology, geomorphology, hydrology, oceanography and, in modern settings, anthropogenic impacts. Compared with small, gravel-bedded river systems, less is known about large, sandy-bed rivers, particularly from the river source to marine sink. In the present study, we examine longitudinal changes in sediment grain size along the middle and lower Yangtze River, downstream of the Three Gorges Dam (TGD), and along the major sediment dispersal pathway into the East China Sea, over a total length of 2100 km. We also examine the spatial patterns of seabed sediment grain size in the East China Sea adjacent to the Yangtze Estuary (70,000 km2 in area). In particular, we consider the impact of the TGD on the grain size of the riverbed and seabed sediments. Before the construction of the TGD, the relationship between median grain size and distance along the sandy bed of the middle and lower Yangtze showed a downstream fining trend that was exponential in form. After the TGD was built, erosion caused an abrupt gravel-sand transition to develop in the section immediately downstream of the TGD. In the Yangtze Estuary, flocculation and subsequent deposition of suspended riverine mud during the slack water period between flood and ebb tides led to the formation of an abrupt sand-mud transition. Muddy deposits along the major longshore sediment dispersal route also show an exponential fining trend. However, towards the open East China Sea, the modern riverine muds are replaced seawards by older sands. The mud margin there was found to have retreated landward significantly over the post-TGD period due to erosion driven by the significant decrease in sediment supply from the Yangtze River. We expect that the impact of the TGD on the grain size of bed sediments in the Yangtze River and the East China Sea will continue for some time, and the change in the grain size

  1. Sharing the rivers: Balancing the needs of people and fish against the backdrop of heavy sediment loads downstream from Mount Rainier, Washington

    NASA Astrophysics Data System (ADS)

    Magirl, C. S.; Czuba, J. A.; Czuba, C. R.; Curran, C. A.

    2012-12-01

    Despite heavy sediment loads, large winter floods, and floodplain development, the rivers draining Mount Rainier, a 4,392-m glaciated stratovolcano within 85 km of sea level at Puget Sound, Washington, support important populations of anadromous salmonids, including Chinook salmon and steelhead trout, both listed as threatened under the Endangered Species Act. Aggressive river-management approaches of the early 20th century, such as bank armoring and gravel dredging, are being replaced by more ecologically sensitive approaches including setback levees. However, ongoing aggradation rates of up to 8 cm/yr in lowland reaches present acute challenges for resource managers tasked with ensuring flood protection without deleterious impacts to aquatic ecology. Using historical sediment-load data and a recent reservoir survey of sediment accumulation, rivers draining Mount Rainer were found to carry total sediment yields of 350 to 2,000 tonnes/km2/yr, notably larger than sediment yields of 50 to 200 tonnes/km2/yr typical for other Cascade Range rivers. An estimated 70 to 94% of the total sediment load in lowland reaches originates from the volcano. Looking toward the future, transport-capacity analyses and sediment-transport modeling suggest that large increases in bedload and associated aggradation will result from modest increases in rainfall and runoff that are predicted under future climate conditions. If large sediment loads and associated aggradation continue, creative solutions and long-term management strategies are required to protect people and structures in the floodplain downstream of Mount Rainier while preserving aquatic ecosystems.

  2. Effect of presence of cellulose in the freshwater sediment on the performance of sediment microbial fuel cell.

    PubMed

    Sajana, T K; Ghangrekar, M M; Mitra, A

    2014-03-01

    The performance of sediment microbial fuel cells (SMFCs) was evaluated in the presence of cellulose in the aquaculture pond sediment as 2% (w/w) in SMFC-2, 4% in SMFC-3 and without adding cellulose in SMFC-1. From aquaculture water, average chemical oxygen demand (COD) and total nitrogen (TN) removal efficiencies of 80.6±0.3% and 83.0±0.01% were obtained in SMFC-1, 88.2±0.5% and 89.6±0.8% in SMFC-2 and 83.1±0.3% and 64.5±1.6% in SMFC-3, respectively. During the complete experimental period, acetic acid was the only short chain fatty acid detected in all three SMFCs. Sediment organic matter removal in SMFC-1, SMFC-2 and SMFC-3 were 16%, 22% and 18.6%, respectively. SMFCs demonstrated effective cellulose degradation from aquaculture pond sediment and maintained the oxidized sediment top layer favourable for aquaculture.

  3. Relative contribution of iron reduction to sediments organic matter mineralization in contrasting habitats of a shallow eutrophic freshwater lake.

    PubMed

    Chen, Mo; Jiang, He-Long

    2016-06-01

    Iron reduction is one of the important organic matter (OM) mineralization pathway in sediments. Here we investigated the rates and the relative contribution of iron reduction to OM mineralization in Zhushan bay (ZSB, cyanobacterial bloom biomass (CBB)-dominated habitats) and East Taihu Lake (ETL, submerged macrophypes (SM)-dominated habitats) of Lake Taihu, China. Anaerobic microcosm incubation revealed that the rate of iron reduction at ZSB (4.42 μmol cm(-3) d(-1)) in summer was almost 1.5 times higher than at ETL (3.13 μmol cm(-3) d(-1)). Iron reduction accounted for 66.5% (ZSB) and 31.8% (ETL) of total anaerobic carbon mineralization, respectively. No detectable methanogenesis was found at ZSB, while methanogenesis was responsible for 16.7% of total anaerobic respiration in sediments of ETL. Geochemical analysis of solid phase constituents indicated that ZSB surface sediments experienced highly oxidizing conditions with much higher amorphous Fe(III) (71 mmol m(-2)) than ETL (11 mmol m(-2)). Conversely, AVS inventories at ETL (38 mmol m(-2)) were up to 30 times higher than at ZSB (1.27 mmol m(-2)), indicating significant sulfate reduction in sediments of ETL. Overall results suggested that varying carbon sources and distinct geochemical characterizations of the sediments in contrasting habitats significantly influenced the rate of iron reduction and the pathway of C mineralization in a large freshwater lake. PMID:27038578

  4. MODIFICATION OF METAL PARTITIONING BY SUPPLEMENTING ACID VOLATILE SULFIDE IN FRESHWATER SEDIMENTS

    EPA Science Inventory

    Acid volatile sulfide is a component of sediments which complexes some cationic metals and thereby influences the toxicity of these metals to benthic organisms. EPA has proposed AVS as a key normalization phase for the development of sediment quality criteria for metals. Experime...

  5. Toxicity and bioaccumulation of sediment-associated contaminants using freshwater invertebrates: A review of methods and applications

    SciTech Connect

    Ingersoll, C.G.; Ankley, G.T.; Benoit, D.A.

    1995-11-01

    This paper reviews recent developments in methods for evaluating the toxicity and bioaccumulation of contaminants associated with freshwater sediments and summarizes example case studies demonstrating the application of these methods. Over the past decade, research has emphasized development of more specific testing procedures for conducting 10-d toxicity tests with the amphipod Hyalella azteca and the midge Chironomus tentans. Toxicity endpoints measured in these tests are survival for H. azteca and survival and growth for C. tentans. Guidance has also been developed for conducting 28-d bioaccumulation tests with the oligochaete Lumbriculus variegatus, including determination of bioaccumulation kinetics for different compound classes. These methods have been applied to a variety of sediments to address issues ranging from site assessments to bioavailability of organic and inorganic contaminants using field-collected and laboratory-spiked samples. Survival and growth of controls routinely meet or exceed test acceptability criteria. Results of laboratory bioaccumulation studies with L. variegatus have been confirmed with comparisons to residues (PCBs, PAHs, DDT) present from synoptically collected field populations of oligochaetes. Additional method development is currently underway to develop chronic toxicity tests and to provide additional data-confirming responses observed in laboratory sediment tests with natural benthic populations.

  6. Sheetflow Effects and Canal Backfilling on Sediment Source and Transport in Everglades Freshwater Marshes: Analysis of Molecular Organic Biomarkers

    NASA Astrophysics Data System (ADS)

    Regier, P.; He, D.; Saunders, C.; Coronado-Molina, C.; Jara, B.; Jaffe, R.

    2014-12-01

    Historic freshwater sheetflow in the Florida Everglades distributed sediment to form a ridge-and-slough landscape. However, drainage along with reduction and obstruction of flow has resulted in degradation of this ridged topography. The DECOMP Physical Model is a landscape-scale project aiming to reestablish natural sheetflow to the central and southern Everglades by redesigning barriers to flow. To validate proof of concept that increased flow will rebuild ridge-slough microtopography, biomarker proxies were established for ridge and slough organic matter sources. In addition, partial and complete canal backfill options were assessed via sediment trap accumulation in each backfill treatment area. Flocculent matter (floc) and sediment samples were collected, solvent extracted, chromatographically separated, and analyzed on a GC/MS using internal standard for quantification. Four molecular organic biomarkers were evaluated: the aquatic proxy (Paq), highly-branched isoprenoids (C20 HBI), kaurenes and botyrococcenes. Paq, an aquatic proxy of mid to long-chain n-alkanes, was shown to clearly differentiate between ridge-derived and slough-derived organic matter with Paq values increasing along ridge-to-slough transects. Kaurenes indicated presence of ridge-derived organic matter while C20 HBI and botyrococcenes were indicative of periphyton-derived organic matter which is commonly more abundant in sloughs. Biomarker distributions during both low (present day) and high (managed) water flow through the DECOMP experimental parcel were determined and discussed comparatively.

  7. Effect of iron on the sensitivity of hydrogen, acetate, and butyrate metabolism to inhibition by long-chain fatty acids in vegetable-oil-enriched freshwater sediments.

    PubMed

    Li, Zhengkai; Wrenn, Brian A; Venosa, Albert D

    2005-08-01

    Freshwater sediment microbial communities enriched by growth on vegetable oil in the presence of a substoichiometric amount of ferric hydroxide (sufficient to accept about 12% of the vegetable-oil-derived electrons) degrade vegetable oil to methane faster than similar microbial communities that develop when sediments are enriched by growth on vegetable oil in the absence of ferric hydroxide. This study examined the effects of enrichment in the presence of Fe(III) on the fatty-acid sensitivity of several important members of anaerobic triglyceride-degrading microbial communities in freshwater sediments. The fatty-acid sensitivity of three groups of microorganisms-hydrogenotrophic methanogens, acetate consumers, and hydrogen-producing acetogens-were investigated by comparing the rates of hydrogen, acetate, or butyrate consumption in the presence and absence of oleic acid. Methanogenesis from hydrogen was not affected by sediment enrichment conditions or by the presence of oleic acid, suggesting that hydrogenotrophic methanogens were insensitive to fatty acid inhibition in these sediments. Oleic acid inhibited the anaerobic degradation rates of acetate and butyrate by 38% and 63%, respectively, but enrichment in the presence of Fe(III) eliminated the fatty-acid sensitivity of acetate degradation and reduced the sensitivity of butyrate degradation by about half. These results suggest that iron-reducing bacteria may provide an alternative pathway through which vegetable oil can be converted to methane in anaerobic freshwater sediments.

  8. Effect Of Iron On The Sensitivity Of Hydrogen, Acetate, And Butyrate Metabolism To Inhibition By Long-Chain Fatty Acids In Vegetable-Oil-Enriched Freshwater Sediments

    EPA Science Inventory

    Freshwater sediment microbial communities enriched by growth on vegetable oil in the presence of a substoichiometric amount of ferric hydroxide (sufficient to accept about 12% of the vegetable-oil-derived electrons) degrade vegetable oil to methane faster than similar microbial c...

  9. Water Velocity and Bioturbation Alter Sediment Resuspension and Biogeochemistry in an Experimental Freshwater Mesocosm System

    NASA Astrophysics Data System (ADS)

    Spivak, A.; Vanni, M. J.

    2010-12-01

    Processes such as bioturbation and resuspension can affect organic matter decomposition by altering sediment redox conditions. Increased oxygen availability may, in turn, affect remineralization rates and larger scale processes such as benthic-pelagic coupling. However, relatively few studies have explicitly tested the simultaneous effects of bioturbation and water velocity on benthic biogeochemistry and sediment resuspension. Using a mesocosm system we conducted two experiments testing the effects of bioturbator identity on particulate and dissolved nutrient dynamics before and after a resuspension event (i.e. water velocity held constant at 0.12 m s-1 for 2 hr; Expt. 1) and rates of sediment resuspension with increasing water velocity (0.00 - 0.20 m s-1; Expt. 2). We manipulated bioturbator identity across four levels as sediments were undisturbed (control), manually punctured (2% of surface area), or disturbed by one of two fish species, either bluegill or catfish. For Expt. 1, the bioturbation treatments were applied for several days and measurements were made before and after the resuspension event. Initially, water column chlorophyll and total suspended sediment (TSS) concentrations were highest in the catfish treatments. Bioturbator identity did not affect the stoichiometry of TSS as strongly; C:N was unaffected by our treatments while N:P was lowest in the disturbed treatments. After the resuspension event, there was no difference in TSS concentrations or stoichiometric ratios across the bioturbation treatments. Dissolved nutrient flux rates were insensitive to the bioturbation treatments and were more strongly influenced by the resuspension event. For instance, sediment NO3- fluxes were negative (i.e. net flux into sediments) until after the resuspension event when they became positive. In Expt. 2, we gradually increased water velocity from 0.00 - 0.20 m s-1 and measured TSS concentrations only. TSS was initially highest in catfish treatments and lowest in

  10. Interlaboratory study of precision: Hyalella azteca and Chironomus tentans freshwater sediment toxicity assays

    USGS Publications Warehouse

    Burton, G.A.; Norberg-King, T. J.; Ingersoll, C.G.; Benoit, D.A.; Ankley, G.T.; Winger, P.V.; Kubitz, J.; Lazorchak, J.M.; Smith, M.E.; Greer, E.; Dwyer, F.J.; Call, D.J.; Day, K.E.; Kennedy, P.; Stinson, M.

    1996-01-01

    Standard 10-d whole-sediment toxicity test methods have recently been developed by the U.S. Environmental Protection Agency (EPA) for the amphipod Hyalella azteca and the midge Chironomus tentans. An interlaboratory evaluation of method precision was performed using a group of seven to 10 laboratories, representing government, academia, and environmental consulting firms. The test methods followed the EPA protocols for 4-d water-only reference toxicant (KCl) testing (static exposure) and for 10-d whole-sediment testing. Test sediments included control sediment, two copper-containing sediments, and a sediment contaminated primarily with polycyclic aromatic hydrocarbons. Reference toxicant tests resulted in H. azteca and C. tentans median lethal concentration (LC50) values with coefficents of variation (CVs) of 15.8 and 19.6%, respectively. Whole sediments which were moderately contaminated provided the best estimates of precision using CVs. Hyalella azteca and C. tentans tests in moderately contaminated sediments exhibited LC50 CVs of 38.9 and 13.5%, respectively. The CV for C. tentans growth was 31.9%. Only 3% (1 of 28) of samples exceeded acceptable interlaboratory precision limits for the H. azteca survival tests. No samples exceeded the intralaboratory precision limit for H. azteca or C. tentans survival tests. However, intralaboratory variability limits for C. tentans growth were exceeded by 80 and 100% of the laboratories for a moderately toxic and control sample, respectively. Interlaboratory variability limits for C. tentans survival were not exceeded by any laboratory. The results showed these test methods to have relatively low variance and acceptable levels of precision in interlaboratory comparisons.

  11. Tidal sediment transport versus freshwater flood events in the Konkouré Estuary, Republic of Guinea

    NASA Astrophysics Data System (ADS)

    Capo, Sylvain; Brenon, Isabelle; Sottolichio, Aldo; Castaing, Patrice; Le Goulven, Patrick

    2009-09-01

    In comparison to their temperate counterparts, sediment processes in tropical estuaries are poorly known and especially in African ones. The hydrodynamics of such environments is controlled by a combination of multiple processes including morphology, salinity, mangrove vegetation, tidal processes, river discharge, settling and erosion of mud and by physico-chemical processes as well as sediment dynamics. The aim of this study is to understand the sediment processes in this transitional stage of the estuary when the balance between river discharges and marine processes is reversing. Studying the hydrodynamics and sediment dynamics of the Konkouré Estuary has recently been made possible thanks to new data on bathymetry, sedimentary cover, salinity, water elevations, and current velocities. The Lower Konkouré is a shallow, funnel shaped, mesotidal mangrove-fringed, tide-dominated estuary, well mixed during low river discharge and stratified during high river discharge. The Konkouré Estuary is turbid despite the small amount of terrestrial input and its residual velocity at the mouth during low river discharges, landwards for two of the three branches, suggests a landward migration by tidal pumping of the suspended particulate matter. A Turbidity Maximum Zone (TMZ) is identified for typical states of the estuary with regard to fluvial and tidal components. Suspended sediment transport during a transitional stage between the rainy and dry seasons is known thanks to current velocity and Suspended Sediment Concentration (SSC) measurements taken in November 2003. The Richardson layered number calculation assesses that turbulence is the major mixing process in the water column, at least during the flood and ebb stages, whereas stratification occurs during the slack water periods. Tidal currents generate bottom erosion, and turbulence mixes the suspended sediment throughout the water column. As a result, a net sediment input is calculated from the western Konkouré outlet

  12. Regiospecific dechlorination of pentachlorophenol by dichlorophenol-adapted microorganisms in freshwater, anaerobic sediment slurries.

    PubMed Central

    Bryant, F O; Hale, D D; Rogers, J E

    1991-01-01

    The reductive dechlorination of pentachlorophenol (PCP) was investigated in anaerobic sediments that contained nonadapted or 2,4- or 3,4-dichlorophenol (DCP)-adapted microbial communities. Adaptation of sediment communities increased the rate of conversion of 2,4- or 3,4-DCP to monochlorophenols (CPs) and eliminated the lag phase before dechlorination was observed. Both 2,4- and 3,4-DCP-adapted sediment communities dechlorinated the six DCP isomers to CPs. The specificity of chlorine removal from the DCP isomers indicated a preference for ortho-chlorine removal by 2,4-DCP-adapted sediment communities and for para-chlorine removal by 3,4-DCP-adapted sediment communities. Sediment slurries containing nonadapted microbial communities either did not dechlorinate PCP or did so following a lag phase of at least 40 days. Sediment communities adapted to dechlorinate 2,4- or 3,4-DCP dechlorinated PCP without an initial lag phase. The 2,4-DCP-adapted communities initially removed the ortho-chlorine from PCP, whereas the 3,4-DCP-adapted communities initially removed the para-chlorine from PCP. A 1:1 mixture of the adapted sediment communities also dechlorinated PCP without a lag phase. Dechlorination by the mixture was regiospecific, following a para greater than ortho greater than meta order of chlorine removal. Intermediate products of degradation, 2,3,5,6-tetrachlorophenol, 2,3,5-trichlorophenol, 3,5-DCP, 3-CP, and phenol, were identified by a combination of cochromatography (high-pressure liquid chromatography) with standards and gas chromatography-mass spectrometry. PMID:1768102

  13. Freshwater macroinvertebrates

    SciTech Connect

    Quigley, M.A.

    1982-06-01

    Major aspects of the biology of freshwater macroinvertebrates with emphasis on man-induced environmental changes were reviewed in this report with 183 references. The effects of both chemical and physical environmental alteration are examined. The population dynamics of the macroinvertebrates are controlled by factors such as food and feeding habits, periodicity and drift, productivity and animal-sediment interactions.(KRM)

  14. Potential ecological risk of heavy metal contamination in sediments and macrobenthos in coastal wetlands induced by freshwater releases: A case study in the Yellow River Delta, China.

    PubMed

    Li, Ming; Yang, Wei; Sun, Tao; Jin, Yuwan

    2016-02-15

    We investigated the nine heavy metal contents in the sediments and macrobenthos of the Yellow River Delta Wetlands using three experimental areas that received freshwater releases and one reference area that did not. Heavy metal contents, the single-factor contamination index (SFCI), the metal contamination index (MCI), and the biota-sediment accumulation factor (BSAF) were used to evaluate the potential ecological risk and bioaccumulation. We found that As exceeded the national standard value by more than 50%, and that the ranges of SFCI for each metal were generally larger in autumn than in spring. MCI showed no clear pattern, but the BSAF results suggest that Cd bioaccumulates from sediments to macrobenthos. Pollution-resistant species such as Corophium sinense, Chironomus sp., and Einfeldia sp. became dominant in the areas receiving freshwater releases, and provide direct evidence of ecological risk in the wetlands. Our results provide preliminary information to guide managers for ecological risk assessments. PMID:26719069

  15. Survival of Frog Virus 3 in Freshwater and Sediment from an English Lake.

    PubMed

    Munro, James; Bayley, Amanda E; McPherson, Nicola J; Feist, Stephen W

    2016-01-01

    Ranaviruses can be transmitted by contaminated water and sediment but must retain infectivity for a sufficient period to reach and infect a susceptible host. To determine the risk a virus represents once it enters the environment, its persistence in that environment must be determined. We evaluated the survival of frog virus 3 (FV3) in water and sediment from an English lake at temperatures of 4, 15, 20, and 30 C over time. The virus survived in both water and sediment; however, survival times were significantly lower in sediment. The virus lost infectivity in both matrices with a rise in temperature. In water, time required for a 90% reduction in virus titer decreased from 34 d at 4 C to 5 d at 30 C. In sediment, required time for a 90% reduction decreased from 10 d at 4 C to 1 d at 30 C. These results can be used to estimate the persistence of FV3 in the environment and indicate that the virus could remain infectious in temperate locations for extended periods during winter.

  16. Water and sediment quality, nutrient biochemistry and pollution loads in an urban freshwater lake: balancing human and ecological services.

    PubMed

    Waltham, Nathan J; Reichelt-Brushett, Amanda; McCann, Damian; Eyre, Bradley D

    2014-12-01

    Optimizing the utility of constructed waterways as residential development with water-frontage, along with a productive and functional habitat for wildlife is of considerable interest to managers. This study examines Lake Hugh Muntz, a large (17 ha) freshwater lake built in Gold Coast City, Australia. A ten year water quality monitoring programme shows that the lake has increasing nutrient concentrations, and together with summer algal blooms, the lake amenity as a popular recreational swimming and triathlon training location is at risk. A survey of fish and aquatic plant communities showed that the lake supports a sub-set of species found in adjacent natural wetlands. Sediment contaminants were below the lower Australian trigger values, except As, Hg, Pb and Zn, probably a function of untreated and uncontrolled stormwater runoff from nearby urban roads. Sediment biogeochemistry showed early signs of oxygen depletion, and an increase in benthic organic matter decomposition and oxygen consumption will result in more nitrogen recycled to the water column as NH4(+) (increasing the intensity of summer algal blooms) and less nitrogen lost to the atmosphere as N2 gas via denitrification. A series of catchment restoration initiatives were modeled and the optimal stormwater runoff restoration effort needed for lake protection will be costly, particularly retrospective, as is the case here. Overall, balancing the lifestyles and livelihoods of residents along with ecosystem protection are possible, but require considerable trade-offs between ecosystem services and human use. PMID:25384753

  17. Biosensor determination of the microscale distribution of nitrate, nitrate assimilation, nitrification, and denitrification in a diatom-inhabited freshwater sediment

    SciTech Connect

    Lorenzen, J.; Larsen, L.H.; Kjaer, T.; Revsbech, N.P.

    1998-09-01

    High-resolution NO{sub 3}{sup {minus}} profiles in freshwater sediment covered with benthic diatoms were obtained with a new microscale NO{sub 3}{sup {minus}} biosensor characterized by absence of interference from chemical species other than NO{sub 2}{sup {minus}} and N{sub 2}O. Analysis of the microprofiles obtained indicated no nitrification during darkness, high rates of nitrification and a tight coupling between nitrification and denitrification during illumination, and substantial rates of NO{sub 3}{sup {minus}} assimilation during illumination. Nitrification during darkness could be induced by purging the bulk water with O{sub 2} gas, indicating that the stimulatory effect on nitrification by illumination was caused by algal production of O{sub 2}. NH{sub 4}{sup +} addition did not stimulate nitrification during darkness when O{sub 2} was restricted to the upper 1-mm layer, and there was thus a low nitrification potential in the permanently oxic top 1 mm of the sediment.

  18. Water and sediment quality, nutrient biochemistry and pollution loads in an urban freshwater lake: balancing human and ecological services.

    PubMed

    Waltham, Nathan J; Reichelt-Brushett, Amanda; McCann, Damian; Eyre, Bradley D

    2014-12-01

    Optimizing the utility of constructed waterways as residential development with water-frontage, along with a productive and functional habitat for wildlife is of considerable interest to managers. This study examines Lake Hugh Muntz, a large (17 ha) freshwater lake built in Gold Coast City, Australia. A ten year water quality monitoring programme shows that the lake has increasing nutrient concentrations, and together with summer algal blooms, the lake amenity as a popular recreational swimming and triathlon training location is at risk. A survey of fish and aquatic plant communities showed that the lake supports a sub-set of species found in adjacent natural wetlands. Sediment contaminants were below the lower Australian trigger values, except As, Hg, Pb and Zn, probably a function of untreated and uncontrolled stormwater runoff from nearby urban roads. Sediment biogeochemistry showed early signs of oxygen depletion, and an increase in benthic organic matter decomposition and oxygen consumption will result in more nitrogen recycled to the water column as NH4(+) (increasing the intensity of summer algal blooms) and less nitrogen lost to the atmosphere as N2 gas via denitrification. A series of catchment restoration initiatives were modeled and the optimal stormwater runoff restoration effort needed for lake protection will be costly, particularly retrospective, as is the case here. Overall, balancing the lifestyles and livelihoods of residents along with ecosystem protection are possible, but require considerable trade-offs between ecosystem services and human use.

  19. Evaluation of potential confounding factors in sediment toxicity tests with three freshwater benthic invertebrates

    SciTech Connect

    Ankley, G.T.; Benoit, D.A. ); Balogh, J.C. ); Reynoldson, T.B.; Day, K.E. ); Hoke, R.A. )

    1994-04-01

    The authors examined the effects of natural sediment physicochemical properties on the results of lab tests with the amphipod Hyalella azteca, the midge Chironomus tentans, and the oligochaete Lumbriculus variegatus. Ten-day exposures with the three species were conducted with 50 uncontaminated sediment samples from Lakes Erie, Huron, Superior, and Ontario, which differed markedly with regard to characteristics such as grain-size distribution, organic carbon content, and mineralogical composition. Tests were conducted both with and without the addition of exogenous food. Survival of Hyalella azteca, survival and growth of Chironomus tentans, and survival/reproduction and growth of Lumbriculus variegatus were significantly greater in tests in which the animals were fed vs, those in which they were not. Approximately 10% of the tests in which Hyalella azteca was not fed and 80% of tests in which the amphipods were fed resulted in >80% survival, a common criterion for defining the acceptability of tests with Hyalella azteca in clean control sediments. Similarly, a relatively high percentage of the tests in which Chironomus tentans was not fed would have failed a control survival criterion of 70% for the midge. Hence, there is significant potential for false positive results if Hyalella azteca or Chironomus tentans is not fed during sediment tests. Predictive modeling of the assay results in relationship to sediment physicochemical characteristics failed to reveal any additional factors that influenced survival of Hyalella azteca and Chrionomus tentans, or reproduction and growth of Lumbriculus variegatus in tests in which the organisms were fed. However, linear modeling did suggest that growth of fed as well as unfed Chironomus tentans may have been influenced by grain-size distribution of the test sediments.

  20. [Phosphorus forms of the suspended particulate matter in the Yellow River downstream during water and sediment regulation 2008].

    PubMed

    Wei, Jun-Feng; Chen, Hong-Tao; Liu, Yue-Liang; Shan, Kai; Yao, Qing-Zhen; He, Hui-Jun; Yu, Zhi-Gang

    2011-02-01

    Suspended particulate matter samples were collected from Lijin Station on the Yellow River during the 2008 water and sediment regulation. Using water elutriation method, samples were physically separated according to grain size, and phosphorus forms were detected by the improved SEDEX technology. Results show that authigenic apatite phosphorus and organic phosphorus are the dominant forms of the particulate phosphorus. During water and sediment regulation, concentrations of total particulate phosphorus, loosely adsorbed phosphorus, organic phosphorus and refractory phosphorus are lower than those in other time of the year, while the concentration of detrital fluorapatite phosphorus is higher than that in other time. Grain size is the primary variable in the determination of the content of various particulate phosphorus forms. In fine particles, loosely adsorbed phosphorus, organic phosphorus and refractory phosphorus concentrations are high, while detrital fluorapatite phosphorus concentration is high in coarse particles. About 28.3% of the total particulate phosphorus is in the form of bio-available phosphorus, of which organic phosphorus is the major component. During the water and sediment regulation, the fluxes of sediment, particulate phosphorus and particulate bio-available phosphorus are 6.63 x 10(7) t, 3.42 x 10(4) t, and 8.30 x 10(3) t, which are 83.2%, 78.6%, and 80.2% each of the total fluxes in 2008.

  1. The phosphorus speciations in the sediments up- and down-stream of cascade dams along the middle Lancang River.

    PubMed

    Liu, Qi; Liu, Shiliang; Zhao, Haidi; Deng, Li; Wang, Cong; Zhao, Qinghe; Dong, Shikui

    2015-02-01

    We detected the longitudinal variability of phosphorus speciations and its relation to metals and grain size distribution of sediments in three cascade canyon reservoirs (Xiaowan, Manwan and Dachaoshan) along Lancang River, China. Five phosphorus speciations including loosely bound P (ex-P), reductant soluble P (BD-P), metal oxide-bound P (NaOH-P) calcium-bound P (HCl-P) and residual-P were extracted and quantified. Results showed that in Manwan Reservoir HCl-P accounted for the largest part of total phosphorus (TP) (49.69%), while in Xiaowan and Dachaoshan reservoirs, NaOH-P was the most abundant speciation which accounted for 57.21% and 55.19% of total phosphorus respectively. Higher contents of bio-available phosphorus in Xiaowan and Dachaoshan reservoirs suggested a high rate of P releasing from sediments. Results also showed ex-P and HCl-P had positive correlation with Ca. Total phosphorus was positively correlated with Fe. The silt/clay contents of the sediments had close relationship with ex-P (r=0.413, p<0.05), NaOH-P (r=0.428, p<0.05) and BAP (r=0.458, p<0.05). The concentration of Ca, Mn and silt/clay speciation in the sediments explained 40%, 10% and 4% of the spatial variation of phosphorus speciations, respectively.

  2. The phosphorus speciations in the sediments up- and down-stream of cascade dams along the middle Lancang River.

    PubMed

    Liu, Qi; Liu, Shiliang; Zhao, Haidi; Deng, Li; Wang, Cong; Zhao, Qinghe; Dong, Shikui

    2015-02-01

    We detected the longitudinal variability of phosphorus speciations and its relation to metals and grain size distribution of sediments in three cascade canyon reservoirs (Xiaowan, Manwan and Dachaoshan) along Lancang River, China. Five phosphorus speciations including loosely bound P (ex-P), reductant soluble P (BD-P), metal oxide-bound P (NaOH-P) calcium-bound P (HCl-P) and residual-P were extracted and quantified. Results showed that in Manwan Reservoir HCl-P accounted for the largest part of total phosphorus (TP) (49.69%), while in Xiaowan and Dachaoshan reservoirs, NaOH-P was the most abundant speciation which accounted for 57.21% and 55.19% of total phosphorus respectively. Higher contents of bio-available phosphorus in Xiaowan and Dachaoshan reservoirs suggested a high rate of P releasing from sediments. Results also showed ex-P and HCl-P had positive correlation with Ca. Total phosphorus was positively correlated with Fe. The silt/clay contents of the sediments had close relationship with ex-P (r=0.413, p<0.05), NaOH-P (r=0.428, p<0.05) and BAP (r=0.458, p<0.05). The concentration of Ca, Mn and silt/clay speciation in the sediments explained 40%, 10% and 4% of the spatial variation of phosphorus speciations, respectively. PMID:25462310

  3. Influence of Reservoir Water Level Fluctuations on Sediment Methylmercury Concentrations Downstream of the Historical Black Butte Mercury Mine, OR

    EPA Science Inventory

    Mercury (Hg) is a pollutant of global concern due to its ability to accumulate as methylmercury (MeHg) in biota. Mercury is methylated by anaerobic microorganisms such as sulfate reducing bacteria (SRB) in water and sediment. Throughout North America, reservoirs tend to have e...

  4. Effects of Low Dissolved Oxygen on Organisms Used in Freshwater Sediment Toxicity Tests

    EPA Science Inventory

    This manuscript describes the results of tests to determine the tolerance of three benthic organisms to reduced dissolved oxygen (DO). These three organisms are those recommended by EPA for use in toxicity testing of contaminated sediments. The results of the exposures indicate ...

  5. Bioavailability and preservation of organic phosphorus in freshwater sediments and its role in lake eutrophication

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lake eutrophication in China is a serious environmental concern, especially in lakes from the middle and lower reaches of Yangtze River region and Southwestern China Plateau. The dissolution of organic matter can result in release of phosphorus (P) from lake sediments and organic phosphate (Po) itse...

  6. Distribution of brominated flame retardants and dechloranes between sediments and benthic fish--A comparison of a freshwater and marine habitat.

    PubMed

    Sühring, Roxana; Busch, Friederike; Fricke, Nicolai; Kötke, Danijela; Wolschke, Hendrik; Ebinghaus, Ralf

    2016-01-15

    A total of 53 halogenated flame retardants (HFRs) were analysed in sediments, European eels and dabs from both freshwater and marine sampling stations in the German Bight and the river Elbe. Classic HFRs, such as polybrominated diphenylethers (PBDEs), were the highest concentrated HFRs in eels as well as in most dabs (apart from 1,2,5,6-tetrabromocyclooctane (TBCO)). In sediments, on the other hand, alternate BFRs and especially dechloranes dominated the contamination pattern. Dabs were still found to be statistically representative for the contamination patterns and relative magnitude in sediments from their respective habitats. Contamination patterns in eels seemed to be more driven by the contamination situation in the food chain or historical contamination of their habitat. Unsuspectedly the alternate flame retardant TBCO was found in comparably high concentrations (up to 12 ng g(-1) ww) in dabs from two sampling stations as well as in sediments from these stations (up to 1.2 ng g(-1) dw). It could not be detected in any other analysed fish or sediment samples, indicating a localised contamination source in the area. This study provides information on HFR contamination patterns and behaviour in both marine and freshwater sediments and their potential role as contamination source for benthic fish. PMID:26544886

  7. Distribution of brominated flame retardants and dechloranes between sediments and benthic fish--A comparison of a freshwater and marine habitat.

    PubMed

    Sühring, Roxana; Busch, Friederike; Fricke, Nicolai; Kötke, Danijela; Wolschke, Hendrik; Ebinghaus, Ralf

    2016-01-15

    A total of 53 halogenated flame retardants (HFRs) were analysed in sediments, European eels and dabs from both freshwater and marine sampling stations in the German Bight and the river Elbe. Classic HFRs, such as polybrominated diphenylethers (PBDEs), were the highest concentrated HFRs in eels as well as in most dabs (apart from 1,2,5,6-tetrabromocyclooctane (TBCO)). In sediments, on the other hand, alternate BFRs and especially dechloranes dominated the contamination pattern. Dabs were still found to be statistically representative for the contamination patterns and relative magnitude in sediments from their respective habitats. Contamination patterns in eels seemed to be more driven by the contamination situation in the food chain or historical contamination of their habitat. Unsuspectedly the alternate flame retardant TBCO was found in comparably high concentrations (up to 12 ng g(-1) ww) in dabs from two sampling stations as well as in sediments from these stations (up to 1.2 ng g(-1) dw). It could not be detected in any other analysed fish or sediment samples, indicating a localised contamination source in the area. This study provides information on HFR contamination patterns and behaviour in both marine and freshwater sediments and their potential role as contamination source for benthic fish.

  8. Mercury species of sediment and fish in freshwater fish ponds around the Pearl River Delta, PR China: human health risk assessment.

    PubMed

    Shao, Dingding; Liang, Peng; Kang, Yuan; Wang, Hongsheng; Cheng, Zhang; Wu, Shengchun; Shi, Jianbo; Lo, Samuel Chun Lap; Wang, Wenxiong; Wong, Ming H

    2011-04-01

    This study investigated total mercury (THg) and methylmercury (MeHg) concentrations in five species of freshwater fish and their associated fish pond sediments collected from 18 freshwater fish ponds around the Pearl River Delta (PRD). The concentrations of THg and MeHg in fish pond surface sediments were 33.1-386 ng g(-1) dry wt and 0.18-1.25 ng g(-1) dry wt, respectively. The age of ponds affected the surface sediment MeHg concentration. The vertical distribution of MeHg in sediment cores showed that MeHg concentrations decreased with increasing depth in the top 10 cm. In addition, a significant correlation was observed between %MeHg and DNA from Desulfovibrionacaea or Desulfobulbus (p<0.05) in sediment cores. Concentrations of THg and MeHg in fish muscles ranged from 7.43-76.7 to 5.93-76.1 ng g(-1) wet wt, respectively, with significant linear relationships (r=0.97, p<0.01, n=122) observed between THg and MeHg levels in fish. A significant correlation between THg concentrations in fish (herbivorous: r=0.71, p<0.05, n=7; carnivorous: r=0.77, p<0.05, n=11) and corresponding sediments was also obtained. Risk assessment indicated that the consumption of largemouth bass and mandarin fish would result in higher estimated daily intakes (EDIs) of MeHg than reference dose (RfD) for both adults and children.

  9. Bioaccumulation and toxicity of a cationic surfactant (DODMAC) in sediment dwelling freshwater invertebrates.

    PubMed

    Comber, S D W; Rule, K L; Conrad, A U; Höss, S; Webb, S F; Marshall, S

    2008-05-01

    Dimethyldioctadecylammonium chloride (DODMAC, CAS No. 107-64-2) is the principal active component of Di(hydrogenated tallow alkyl) dimethylammonium chloride (DHTDMAC, CAS No. 61789-80-8), a cationic surfactant formerly used principally in laundry fabric softeners. After discharge to water, DODMAC partitions strongly to sediment, therefore the assessment of the effects of DODMAC to benthic organisms is essential in any risk assessment. Chronic toxicity studies were conducted with Lumbriculus variegatus (Oligochaete), Tubifex tubifex (Oligochaete) and Caenorhabditis elegans (Nematode). NOECs were greater than 5738, 1515 and 1351 mg/kg dw, respectively, even for sub-lethal effects. Measurement of the route of uptake of DODMAC by L. variegatus demonstrated the relative importance of uptake via ingestion (86%) compared with direct contact with the sediment and via pore water (14%). The overall tendency of DODMAC to bioaccumulate, however, was low with measured accumulation factors of 0.22 and 0.78 for L. variegatus and T. tubifex, respectively. PMID:17889974

  10. Fullerene nanoparticles exhibit greater retention in freshwater sediment than in model porous media.

    PubMed

    Zhang, Wei; Isaacson, Carl W; Rattanaudompol, U-sa; Powell, Tremaine B; Bouchard, Dermont

    2012-06-01

    Increasing production and use of fullerene-based nanomaterials underscore the need to determine their mobility in environmental transport pathways and potential ecological exposures. This study investigated the transport of two fullerenes (i.e., aqu/C(60) and water-soluble C(60) pyrrolidine tris-acid [C(60) PTA]) in columns packed with model porous media (Iota quartz and Ottawa sand) and a sediment from Call's creek under saturated and unsaturated steady-state flows. The fullerenes had the least retention in Iota quartz, and the greatest retention in the sediment at near neutral pH, correlating with the degree of grain surface chemical heterogeneity (e.g., amorphous Al hydroxides concentration increasing in the order of Iota quartzsediment). Surface roughness was elucidated as another important factor responsible for the greatest fullerene retention in the sediment. In accordance with the XDLVO energy calculations, C(60) PTA was less retained than aqu/C(60) at near neutral pH, due to its greater hydrophilicity measured by tolune-water partition coefficient, as well as smaller particle sizes revealed by atomic force microscopy. Fullerene retention exhibited a strong dependency on solution pH that could be explained partly by the pH-dependent surface charge of fullerenes and grain surface, and partly by increased hydrophobicity of C(60) PTA when solution pH approaches its isoelectric point (IEP). Finally, fullerene retention was enhanced in unsaturated media, implying that fullerenes may be more attenuated in the vadose zone than in groundwater. PMID:22445188

  11. EXAFS analysis of iron cycling in mangrove sediments downstream a lateritized ultramafic watershed (Vavouto Bay, New Caledonia)

    NASA Astrophysics Data System (ADS)

    Noël, Vincent; Marchand, Cyril; Juillot, Farid; Ona-Nguema, Georges; Viollier, Eric; Marakovic, Gregory; Olivi, Luca; Delbes, Ludovic; Gelebart, Frédéric; Morin, Guillaume

    2014-07-01

    Mangrove forests are the dominant intertidal ecosystem of tropical coastlines. In New Caledonia, mangroves act as a buffer zone between massive Fe lateritic deposits and a lagoon partly registered by UNESCO as a World Heritage site. The New Caledonian mangroves are characterized by a botanical gradient composed of three main vegetal stands (i.e., Rhizophora spp., Avicennia marina and salt flat), which relies on the duration of tidal immersion that imposes gradients of pore-water salinity, oxygenation, and organic content in the sediment. In the present study, we have determined the distribution and speciation of Fe in mangrove sediments along this botanical gradient by using X-ray absorption spectroscopy (XAS) at the Fe K-edge. Both XANES and EXAFS results show that iron speciation strongly follows the redox boundaries marking the intertidal and depth zonations. Fe-bearing minerals eroded from lateritic outcrops, mainly goethite (α-FeOOH) and phyllosilicates (serpentine and talc), are the major Fe hosts in the upward horizons. These mineral species progressively disappear with increasing depth where pyrite (FeS2) forms, in the hydromorphic Rhizophora and Avicennia zones. Sulfate reduction is not observed in the drier salt flat zone. In addition to these reduction processes, intense re-oxidation of aqueous Fe(II) and pyrite leads to the formation of poorly ordered ferrihydrite, lepidocrocite (γ-FeOOH) and likely goethite in the upper sediments beneath Avicennia and Rhizophora stands. The relative proportion of the newly formed poorly ordered ferrihydrite and lepidocrocite is found to be higher in the Rhizophora mangrove stand, which is the closest to the shore. Tidal fluctuations may thus be a major cause for continuous Fe reduction-oxidation cycles in the vegetated mangrove stands, which could significantly affect the iron mass balance in mangrove systems.

  12. Effects of spatial and temporal variation of acid-volatile sulfide on the bioavailability of copper and zinc in freshwater sediments

    SciTech Connect

    Besser, J.M.; Ingersoll, C.G.; Giesy, J.P.

    1996-03-01

    Variation in concentrations of acid-volatile sulfide (AVS) in sediments from the upper Clark Fork River of Montana, USA, was associated with differences in bioaccumulation of Cu and Zn and growth of larvae of the midge, Chironomus tentans. Growth of midge larvae was significantly greater and bioaccumulation of Cu was significantly less in surface sections (0--3 cm depth) of sediment cores, which had greater concentrations of AVS and lesser ratios of simultaneously extracted metals to AVS (SEM:AVS ratios) than in subsurface sediments (6--9 cm). Concentrations of AVS were significantly less in sediments incubated with oxic overlying water for 9 weeks than in the same sediments incubated under anoxic conditions. Bioaccumulation of Cu differed significantly between incubation treatments, corresponding to differences in concentrations of AVS and SEM:AVS ratios, although midge growth did not. Bioaccumulation of Zn did not differ significantly between depth strata of sediment cores or between incubation treatments. When results from the two sets of bioassays were combined, bioaccumulation of Cu and Zn, but not growth, was significantly correlated with SEM:AVS ratios and other estimates of bioavailable metal fractions in sediments. Growth of midge larvae was significantly correlated with bioaccumulation of Zn, but not Cu, suggesting that Zn was the greater contributor to the toxicity of these sediments. Assessments of the toxicity of metal-contaminated freshwater sediments should consider the effects of spatial and temporal variation in AVS concentrations on metal bioavailability.

  13. Desulfuromonas thiophila sp. nov., a new obligately sulfur-reducing bacterium from anoxic freshwater sediment

    USGS Publications Warehouse

    Finster, K.; Coates, J.D.; Liesack, W.; Pfennig, N.

    1997-01-01

    A mesophilic, acetate-oxidizing, sulfur-reducing bacterium, strain NZ27(T), was isolated from anoxic mud from a freshwater sulfur spring. The cells were ovoid, motile, and gram negative. In addition to acetate, the strain oxidized pyruvate, succinate, and fumarate. Sulfur flower could be replaced by polysulfide as an electron acceptor. Ferric nitrilotriacetic acid was reduced in the presence of pyruvate; however, this reduction did not sustain growth. These phenotypic characteristics suggested that strain NZ27(T) is affiliated with the genus Desulfuromonas. A phylogenetic analysis based on the results of comparative 16S ribosomal DNA sequencing confirmed that strain NZ27(T) belongs to the Desulfuromonas cluster in the recently proposed family 'Geobacteraceae' in the delta subgroup of the Proteobacteria. In addition, the results of DNA-DNA hybridization studies confirmed that strain NZ27(T) represents a novel species. Desulfuromonas thiophila, a name tentatively used in previous publications, is the name proposed for strain NZ27(T) in this paper.

  14. Rotenone persistence in freshwater ponds: Effects of temperature and sediment adsorption

    USGS Publications Warehouse

    Dawson, V.K.; Gingerich, W.H.; Davis, R.A.; Gilderhus, P.A.

    1991-01-01

    The persistence of rotenone was compared between a cement-lined pond (0.04 hectare) and an earthen-bottom pond (0.02 hectare) treated with 5 I?L Noxfish/L (250 I?g rotenone/L) during spring, summer, and fall. Water temperatures on the days of treatment in each season were 8, 22, and 15A?C, respectively. Both ponds were filled with pond water from a common source 1 week before each of the three treatments. Water samples (filtered and unfiltered) and sediment samples were analyzed by high-performance liquid chromatography to monitor the decrease of rotenone until residues were at or below the detection limit (<2.0 I?g/L for water and < 25 ng/g for sediments). The loss of rotenone from water generally followed a first-order rate ofdecay. Rotenone disappeared two to three times faster in the earthen pond than in the concrete pond. The rotenone half-life times in the spring, summer, and fall treatments were 3.7, 1.3, and 5.2 d, respectively, in the concrete pond, and 1.8, 0.7, and 1.8 d in the earthen pond. Rates of decay in both ponds were directly correlated with water temperature. Filtered water samples from both ponds contained less rotenone than unfiltered water, indicating that some rotenone was bound to suspended material. The highest concentration of rotenone in sediment samples was 102 ng/g; residues decreased to below the detection limit within 14 d in the spring treatment and within 3 d in the summer and fall treatments.

  15. Influence of sulfate input on freshwater sediments: Insights from incubation experiments

    USGS Publications Warehouse

    Szynkiewicz, Anna; Jedrysek, Mariusz Orion; Kurasiewicz, M.; Mastalerz, Maria

    2008-01-01

    Incubation experiments were carried out under high and low SO42 - conditions to investigate the buffering capacity of lake sediments. Increased SO42 - content in the water column enhanced microbial SO42 - reduction, causing a continuous decrease of SO42 - content from 1086 to 83 mg/L paralleled by an increase of pH in the water column from 3.76 to 7.20. These changes were accompanied by decreased methanogenesis in the incubated sediments. The results demonstrate that the buffering capacity resulted from a variety of biodegradation pathways controlled to a large extent by SO42 - reduction, rather than by direct anaerobic oxidation of CH4. This is documented by distinctly lower ??13C values (from -73.99 to -65.24???) of the CH4 generated under higher SO42 - conditions compared to higher ??13C values (from -68.98 to -61.37???) of the CH4 generated under lower SO42 - conditions. ?? 2008 Elsevier Ltd. All rights reserved.

  16. Chemometrical assessment of the electrical parameters obtained by long-term operating freshwater sediment microbial fuel cells.

    PubMed

    Mitov, Mario; Bardarov, Ivo; Mandjukov, Petko; Hubenova, Yolina

    2015-12-01

    The electrical parameters of nine freshwater sediment microbial fuel cells (SMFCs) were monitored for a period of over 20 months. The developed SMFCs, divided into three groups, were started up and continuously operated under different constant loads (100, 510 and 1100 Ω) for 2.5 months. At this stage of the experiment, the highest power density values, reaching 1.2 ± 0.2 mW/m(2), were achieved by the SMFCs loaded with 510 Ω. The maximum power obtained at periodical polarization during the rest period, however, ranged between 26.2 ± 2.8 and 35.3 ± 2.8 mW/m(2), strongly depending on the internal cell resistance. The statistical evaluation of data derived from the polarization curves shows that after 300 days of operation all examined SMFCs reached a steady-state and the system might be assumed as homoscedastic. The estimated values of standard and expanded uncertainties of the electric parameters indicate a high repeatability and reproducibility of the SMFCs' performance. Results obtained in subsequent discharge-recovery cycles reveal the opportunity for practical application of studied SMFCs as autonomous power sources.

  17. Mississippi freshwater discharge and terrigenous sediment supply into the northern Gulf of Mexico and Loop Current dynamics over glacial/interglacial changes

    NASA Astrophysics Data System (ADS)

    Nuernberg, D.; Kujau, A.; Rieken, S.; Bahr, A.; Karas, C.; Ziegler, M.

    2011-12-01

    We here present (isotope)geochemical and sedimentological data from marine sediment cores from the northern Gulf of Mexico to approximate the temporally and spatially varying terrigenous sediment contribution via the Mississippi River and the related spread of freshwater over the last glacial-interglacial cycles, with specific focus on the last ca. 42.000 years. Our study is based on cores from the DeSoto Canyon (MD02-2576 and 2575), from ~90 km southeast off the Mississippi River delta (M78-181), and from southwest of the delta (IODP 1319A). The geochemical signature of the eastern cores closely matches that of the Mississippi catchment area rather than those of the Alabama and Mobile River catchments. In particular, the siliciclastic major element potassium (K), estimated from calibrated XRF core scanning, serves as a suitable proxy for Mississippi River sediment discharge, becoming less concentrated with distance from the delta. The K variability suggests enhanced glacial phase terrigenous influx triggered by strengthened fluvial runoff and changing fluvial and ice sheet dynamics. Mississippi River influx was at a maximum during glacial MIS 2/3, late MIS 8 and MIS 10, reflected by sedimentation rates being 4 to 5 times higher than in the Holocene. Late glacial to deglacial fluvial sediment supply, however, decreased abruptly at ca. 20 ka at our easternmost core location (MD02-2576), and ca. 2 kyr later at our core location closest to the Mississippi Delta, implying a gradual westward shift of the Mississippi outflow. Due to synchronous changes in sea-surface temperatures, we hypothesize an increasing impact of the northward extending Loop Current on the Mississippi outflow pattern. Combined stable oxygen isotope and element ratios from shallow and deep-dwelling as well as benthic foraminifers allow to approximate paleosalinity, and hence to follow the dispersal of freshwater across the Gulf of Mexico. According to our data, Mississippi freshwater discharge

  18. Unexpected Diversity of pepA Genes Encoding Leucine Aminopeptidases in Sediments from a Freshwater Lake.

    PubMed

    Tsuboi, Shun; Yamamura, Shigeki; Imai, Akio; Iwasaki, Kazuhiro

    2016-01-01

    We herein designed novel PCR primers for universal detection of the pepA gene, which encodes the representative leucine aminopeptidase gene, and investigated the genetic characteristics and diversity of pepA genes in sediments of hypereutrophic Lake Kasumigaura, Japan. Most of the amino acid sequences deduced from the obtained clones (369 out of 370) were related to PepA-like protein sequences in the M17 family of proteins. The developed primers broadly detected pepA-like clones associated with diverse bacterial phyla-Alpha-, Beta-, Gamma-, and Deltaproteobacteria, Acidobacteria, Actinobacteria, Aquificae, Chlamydiae, Chloroflexi, Cyanobacteria, Firmicutes, Nitrospirae, Planctomycetes, and Spirochetes as well as the archaeal phylum Thaumarchaeota, indicating that prokaryotes in aquatic environments possessing leucine aminopeptidase are more diverse than previously reported. Moreover, prokaryotes related to the obtained pepA-like clones appeared to be r- and K-strategists, which was in contrast to our previous findings showing that the neutral metalloprotease gene clones obtained were related to the r-strategist genus Bacillus. Our results suggest that an unprecedented diversity of prokaryotes with a combination of different proteases participate in sedimentary proteolysis. PMID:26936797

  19. Unexpected Diversity of pepA Genes Encoding Leucine Aminopeptidases in Sediments from a Freshwater Lake

    PubMed Central

    Tsuboi, Shun; Yamamura, Shigeki; Imai, Akio; Iwasaki, Kazuhiro

    2016-01-01

    We herein designed novel PCR primers for universal detection of the pepA gene, which encodes the representative leucine aminopeptidase gene, and investigated the genetic characteristics and diversity of pepA genes in sediments of hypereutrophic Lake Kasumigaura, Japan. Most of the amino acid sequences deduced from the obtained clones (369 out of 370) were related to PepA-like protein sequences in the M17 family of proteins. The developed primers broadly detected pepA-like clones associated with diverse bacterial phyla—Alpha-, Beta-, Gamma-, and Deltaproteobacteria, Acidobacteria, Actinobacteria, Aquificae, Chlamydiae, Chloroflexi, Cyanobacteria, Firmicutes, Nitrospirae, Planctomycetes, and Spirochetes as well as the archaeal phylum Thaumarchaeota, indicating that prokaryotes in aquatic environments possessing leucine aminopeptidase are more diverse than previously reported. Moreover, prokaryotes related to the obtained pepA-like clones appeared to be r- and K-strategists, which was in contrast to our previous findings showing that the neutral metalloprotease gene clones obtained were related to the r-strategist genus Bacillus. Our results suggest that an unprecedented diversity of prokaryotes with a combination of different proteases participate in sedimentary proteolysis. PMID:26936797

  20. Distribution and diversity of fungi in freshwater sediments on a river catchment scale

    PubMed Central

    Liu, Jie; Wang, Jianan; Gao, Guanghai; Bartlam, Mark G.; Wang, Yingying

    2015-01-01

    Fungal communities perform essential functions in biogeochemical cycles. However, knowledge of fungal community structural changes in river ecosystems is still very limited. In the present study, we combined culture-dependent and culture-independent methods to investigate fungal distribution and diversity in sediment on a regional scale in the Songhua River catchment, located in North-East Asia. A total of 147 samples over the whole river catchment were analyzed. The results showed that compared to the mainstream, the tributaries have a higher fungal community organization and culturable fungal concentration, but possess lower community dynamics as assessed by denaturing gradient gel electrophoresis (DGGE). Furthermore, phylogenetic analysis of DGGE bands showed that Ascomycota and Basidiomycota were the predominant community in the Songhua River catchment. Redundancy analysis revealed that longitude was the primary factor determining the variation of fungal community structure, and fungal biomass was mainly related to the total nutrient content. Our findings provide new insights into the characteristics of fungal community distribution in a temperate zone river at a regional scale, and demonstrate that fungal dispersal is restricted by geographical barriers in a whole river catchment. PMID:25954259

  1. Determination of plutonium isotopes in freshwater lake sediments by sector-field ICP-MS after separation using ion-exchange chromatography.

    PubMed

    Liao, Haiqing; Zheng, Jian; Wu, Fengchang; Yamada, Masatoshi; Tan, Mingguang; Chen, Jianmin

    2008-08-01

    The determination of Pu isotopes in lake sediments is important for many studies, such as Pu pollution source identification, sediment mixing estimation, erosion evaluation and establishment of deposition chronology in lakes. In this paper, a simple analytical method using sector field inductively coupled plasma mass spectrometry (ICP-MS) combined with two-stage chromatographic separation and purification of Pu was developed based on the optimization and adaptation of the previously published method for marine samples with an emphasis on the study of the elimination of interferences for the analysis of freshwater lake sediments. A strong base anion-exchange resin (AG MP-1M) was used to purify Pu isotopes with concentrated HBr as the final eluent for Pu elution. The chemical yields were ca. 64% and the decontamination factor for U was ca. 10(5). The developed method was validated using a freshwater lake sediment reference material (SRM-4354) and a marine sediment reference material (IAEA-368), and applied to the determination of Pu isotopes in sediment samples of Lake Poyang, East China. For the analysis of certified reference materials, both 239+240Pu activity of 31.6 mBq g(-1) and 240Pu/239Pu atom ratio of 0.033 for IAEA-368 were comparable to the certified value and/or literature values. As for SRM-4354, 239+240Pu activity of 3.90 mBq g(-1) agreed well with the certified value. However, the mean 240Pu/239Pu atom ratio of 0.144 was lower than those reported by other laboratories. This difference suggested that this material may be isotopically inhomogeneous. 240Pu/239Pu atom ratios of Poyang Lake sediment samples ranged from 0.185 to 0.192 with a mean value of 0.187+/-0.004, indicating that plutonium pollution originated from global fallout. PMID:18276148

  2. Methanobacterium lacus sp. nov., isolated from the profundal sediment of a freshwater meromictic lake.

    PubMed

    Borrel, Guillaume; Joblin, Keith; Guedon, Annie; Colombet, Jonathan; Tardy, Vincent; Lehours, Anne-Catherine; Fonty, Gérard

    2012-07-01

    An autotrophic, hydrogenotrophic methanogen, designated strain 17A1(T), was isolated from the profundal sediment of the meromictic Lake Pavin, France. The cells of the novel strain, which were non-motile, Gram-staining-negative rods that measured 2-15 µm in length and 0.2-0.4 µm in width, grew as filaments. Strain 17A1(T) grew in a mineral medium and its growth was stimulated by the addition of yeast extract, vitamins, acetate or rumen fluid. Penicillin, vancomycin and kanamycin reduced growth but did not completely inhibit it. Growth occurred at 14-41 °C (optimum 30 °C), at pH 5.0-8.5 (optimum pH 6.5) and with 0-0.4 M NaCl (optimum 0.1 M). The novel strain utilized H(2)/CO(2) and methanol/H(2) as substrates but not formate, acetate, methylamine/H(2), isobutanol or 2-propanol. Its genomic DNA G+C content was 37.0 mol%. In phylogenetic analyses based on 16S rRNA gene sequences, strain 17A1(T) appeared to be a member of the genus Methanobacterium, with Methanobacterium beijingense 8-2(T) (96.3% sequence similarity) identified as the most closely related established species. Based on phenotypic and phylogenetic data, strain 17A1(T) represents a novel species of methanogen within the genus Methanobacterium, for which the name Methanobacterium lacus sp. nov. is proposed. The type strain is 17A1(T) (=DSM 24406(T)=JCM 17760(T)).

  3. A DNA Microarray Platform Based on Direct Detection of rRNA for Characterization of Freshwater Sediment-Related Prokaryotic Communities

    PubMed Central

    Peplies, Jörg; Lachmund, Christine; Glöckner, Frank Oliver; Manz, Werner

    2006-01-01

    A DNA microarray platform for the characterization of bacterial communities in freshwater sediments based on a heterogeneous set of 70 16S rRNA-targeted oligonucleotide probes and directly labeled environmental RNA was developed and evaluated. Application of a simple protocol for the efficient background blocking of aminosilane-coated slides resulted in an improved signal-to-noise ratio and a detection limit of 10 ng for particular 16S rRNA targets. An initial specificity test of the system using RNA from pure cultures of different phylogenetic lineages showed a fraction of false-positive signals of ∼5% after protocol optimization and a marginal loss of correct positive signals. Subsequent microarray analysis of sediment-related community RNA from four different German river sites suggested low diversity for the groups targeted but indicated distinct differences in community composition. The results were supported by parallel fluorescence in situ hybridization in combination with sensitive catalyzed reporter deposition (CARD-FISH). In comparisons of the data of different sampling sites, specific detection of populations with relative cellular abundances down to 2% as well as a correlation of microarray signal intensities and population size is suggested. Our results demonstrate that DNA microarray technology allows for the fast and efficient precharacterization of complex bacterial communities by the use of standard single-cell hybridization probes and the direct detection of environmental rRNA, also in methodological challenging habitats such as heterogeneous lotic freshwater sediments. PMID:16820477

  4. Effect of Wastewater Treatment Plant Effluent on Microbial Function and Community Structure in the Sediment of a Freshwater Stream with Variable Seasonal Flow▿

    PubMed Central

    Wakelin, Steven A.; Colloff, Matt J.; Kookana, Rai S.

    2008-01-01

    We investigated the effects of wastewater treatment plant (WWTP) discharge on the ecology of bacterial communities in the sediment of a small, low-gradient stream in South Australia. The quantification of genes involved in the biogeochemical cycling of carbon and nitrogen was used to assess potential impacts on ecosystem functions. The effects of disturbance on bacterial community structure were assessed by PCR-denaturing gradient gel electrophoresis of 16S rRNA genes, and clone library analysis was used to phylogenetically characterize significant shifts. Significant (P < 0.05) shifts in bacterial community structures were associated with alteration of the sediment's physicochemical properties, particularly nutrient loading from the WWTP discharge. The effects were greatest at the sampling location 400 m downstream of the outfall where the stream flow is reduced. This highly affected stretch of sediment contained representatives of the gammaproteobacteria that were absent from less-disturbed sites, including Oceanospirillales and Methylococcaceae. 16S rRNA gene sequences from less-disturbed sites had representatives of the Caulobacteraceae, Sphingomonadaceae, and Nitrospirae which were not represented in samples from disturbed sediment. The diversity was lowest at the reference site; it increased with proximity to the WWTP outfall and declined toward highly disturbed (400 m downstream) sites (P < 0.05). The potential for biological transformations of N varied significantly with the stream sediment location (P < 0.05). The abundance of amoA, narG, and nifH genes increased with the distance downstream of the outfall. These processes are driven by N and C availability, as well as redox conditions. Together these data suggest cause and effect between nutrient loading into the creek, shift in bacterial communities through habitat change, and alteration of capacity for biogeochemical cycling of N. PMID:18344343

  5. Toxicokinetics of sediment-sorbed benzo[a]pyrene and hexachlorobiphenyl using the freshwater invertebrates Hyalella azteca, Chironomus tentans, and Lumbriculus variegatus.

    PubMed

    Schuler, Lance J; Wheeler, Matthew; Bailer, A John; Lydy, Michael J

    2003-02-01

    This study investigated the effect of long-term sediment aging on the toxicokinetics of benzo[a]pyrene (BaP) and hexachlorobiphenyl (HCBP) using three freshwater benthic invertebrates. Hyalella azteca, Chironomus tentans, and Lumbriculus variegatus were exposed to BaP- and HCBP-spiked sediments that were aged for 7 d or 1.5 years. The toxicokinetics of the two compounds were determined for each test organism using a two-compartment model. The modeling of BaP was more complex because biotransformation was included within the model. The results of this study showed that the HCBP uptake clearance rates (k(s)) for each species were generally an order of magnitude greater than those determined for BaP and this difference was most likely due to preferential and rapid binding of BaP to sediment particles. Overall, the bioavailability of HCBP in spiked sediments tended to decrease with duration of aging, based on k(s) values and bioaccumulation factors (BAFs). However, the decreases in bioavailability appear to be species specific. Benzo[a]pyrene did not decline in bioavailability for the species tested because it may resist movement into the micropores of the sediment due to its large size. In addition to the bioassays, this article outlines a method for toxicokinetic modeling of biotransformed compounds and methods for statistical comparisons of kinetic parameters (i.e., k(s), k(d)...) and BAF values.

  6. Effect of metal mixture (Cu, Zn, Pb, and Ni) on cadmium partitioning in littoral sediments and its accumulation by the freshwater macrophyte Eriocaulon septangulare

    SciTech Connect

    Stewart, A.R.; Malley, D.F.

    1999-03-01

    The effect of a metal mixture (Cu, Zn, Pb, and Ni) on Cd fractionation in sediment and its accumulation by the freshwater macrophyte Eriocaulon septangulare was examined in an in situ experiment in the littoral zone at the Experimental Lakes Area, northwestern Ontario, Canada. Fresh sediment was spiked with Cd alone and together with the metal mixture at three concentration levels. Macrophytes were planted in the spiked sediment and placed at a water depth of 0.5 m. The distribution of Cd among sediment fractions (easily reducible [ER], reducible [R-ER], and organic [ORG]), pore water, and macrophytes was determined every 2 weeks for 10 weeks. Small differences among treatment levels in the recovery of Cd from the geochemical fractions were observed after 2 and 8 weeks but not after 10 weeks. At the highest concentration of the metal mixture, Cd repartitioned from the ER fraction onto the R-ER fraction after 2 weeks in situ. After 10 weeks, Cd was accumulated by the shoots and roots of E. septangulare and had not reached steady state. Significantly higher Cd concentrations were found in the shoots of plants in the treatment with Cd alone and the treatment with the highest concentration of the metal mixture than in treatments with intermediate levels of the mixture. Partitioning of Cd among geochemical fractions in sediment alone did not explain differences in tissue Cd concentrations related to treatment level.

  7. Uptake and metabolism of benzo(a)pyrene absorbed to sediment by the freshwater invertebrate species Chironomus riparius and Sphaerium corneum

    SciTech Connect

    Borchert, J.; Karbe, L.; Westendorf, J.

    1997-01-01

    The polyaromatic hydrocarbon (PAH) Benzo(a)pyrene (BP) is a widespread contaminant, which is known to be carcinogenic in mammals after ic activation. BP is released into the environment and the water as a by-product of combustion of fossil and recent material (fuel, wood) in industry, traffic and households and is also released by natural sources. Most of the PAHs are highly lipophilic and therefore bound to humic substances, dissolved macromolecules and particulate matter which are at least deposited in the aquatic sediments. The BP concentrations in sediments of pristine waters do normally not exceed 1 {mu}g/g dry weight (dw). In polluted waters of industrial areas, the BP concentration may increase up to 100 {mu}g/g dw. The risk for environmental health caused by such sediment bound PAHs can be assessed by using BP as a model substance. One aim of this study was to investigate if the sediment bound BP is bioavailable to sediment dwelling organisms. For this purpose we examined the uptake of sediment bound BP. The metabolism of PAHs in insects has been investigated, however, only little is known about the Phase I and Phase II metabolism in clams, especially in freshwater species. The organisms choosen were two sediment inhabiting invertebrates, the larvae of the midge Chironomus riparius and the European fingernail clam Sphaerium corneum. Also investigated was the question of whether the BP taken up by the test organisms undergoes metabolic activation, since the toxicity of BP is modulated by metabolism. 11 refs., 3 figs., 4 tabs.

  8. Assessment of heavy metals and arsenic contamination in the sediments of the Moulouya River and the Hassan II Dam downstream of the abandoned mine Zeïda (High Moulouya, Morocco)

    NASA Astrophysics Data System (ADS)

    El Azhari, Abdellah; Rhoujjati, Ali; EL Hachimi, Moulay Laârabi

    2016-07-01

    To evaluate the sediment contamination level near the abandoned (PbZn) mine Zeïda, heavy metal concentrations were determined in sediment samples from the Moulouya River, the Ansegmir tributary and the Hassan II Dam located downstream of the abandoned mine. These samples were analysed for their geochemical properties: mineralogy by XRD, carbonate content, pH, particle size and the total concentrations of Pb, Zn, As and Cu elements by ICP-AES. The assessment of the sediment pollution extent was performed by using the multiple pollution indices: contamination factor (CF), pollution load index (PLI) and the geoaccumulation index (Igeo). The Highest CF values (>6) of Pb that have been observed downstream of the tailings promote a high Pb contamination in that specific area. The PLIs results showed that all stations, except for those upstream of the tailings and on the Hassan II Dam, have been found moderately to highly contaminated. The Igeo results confirmed the Pb high contamination but also the extreme As contamination. The potential ecological risk factor results and the comparison with the sediment quality guidelines revealed that the Pb and As levels are potentially toxic to the sediment-dwelling organisms. Based on the multivariate statistical analysis results and the spatial distribution of the sediment contamination level, the pollution of Pb and As have different sources. Pb contamination is located exclusively near and downstream of the tailings. These latter's may be considered as an important point source of Pb into the Moulouya River. The As contamination is derived from a larger scale input sources which can be related to anthropogenic and/or lithogenic effects.

  9. Methymercury Formation in Marine and Freshwater Systems: Sediment Characteristics, Microbial Activity and SRB Phylogeny Control Formation Rates and Food-Chain Exposure

    NASA Astrophysics Data System (ADS)

    King, J. K.; Saunders, F. M.

    2004-05-01

    Mercury research in freshwater and marine systems suggests that sediment characteristics such as organic substrate, mercury speciation, and sulfate/sulfide concentrations influence availability of inorganic mercury for methylation. Similarly, sediment characteristics also influence sulfate-reducing bacterial (SRB) respiration as well as the presence/distribution of phylogenetic groups responsible for mercury methylation. Our work illustrates that the process of methylmercury formation in freshwater and marine systems are not dissimilar. Rather, the same geochemical parameters and SRB phylogenetic groups determine the propensity for methylmercury formation and are applicable in both fresh- and marine-water systems. The presentation will include our integration of sediment geochemical and microbial parameters affecting mercury methylation in specific freshwater and marine systems. Constructed wetlands planted with Schoenoplectus californicus and amended with gypsum (CaSO4) have demonstrated a capacity to remove inorganic mercury from industrial outfalls. However, bioaccumulation studies of periphyton, eastern mosquitofish (Gambusia holbrooki) and lake chubsucker (Erimyzon sucetta) were conducted in order to ascertain the availability of wetland-generated methylmercury to biota. Total mercury concentrations in mosquitofish from non-sulfate treated controls and the reference location were significantly lower than those from the low and high sulfate treatments while mean total mercury concentrations in lake chubsuckers were also significantly elevated in the high sulfate treatment compared to the low sulfate, control and reference populations. Methylmercury concentrations in periphyton also corresponded with mercury levels found in the tissue of the lake chubsuckers, and these findings fit well given the trophic levels identified for both species of fish. Overall, data from this study suggest that the initial use of gypsum to accelerate the maturity of a constructed

  10. Streamflow and sediment data collected at seven stream-gaging stations in the James River basin downstream from Forestburg, South Dakota, from October 1, 1982 to September 30, 1983

    USGS Publications Warehouse

    Little, J.R.

    1985-01-01

    A compilation of streamflow and suspended-sediment data collected from October 1, 1982, to September 30, 1983, at seven gaging stations in the James River basin downstream from Forestburg, South Dakota, is presented in tabular and graphic form. Three of the gaging stations are on the main stem and four are on tributary streams. These are the results from the second year of a two-year study in cooperation with the Lower James Conservancy Sub-District. The data listed in the tables and figures include location, a summary of the streamflow for the period of record, tables listing the daily streamflow, mean suspended-sediment concentration, and suspended-sediment discharge; and figures showing the daily streamflow, mean suspended-sediment concentration and suspended-sediment discharge for each gaging station. Sandbars are developing in the river and this data is to be used in studies analyzing sources of the sediment and tributary sediment loads relative to those carried by the main stem. (USGS)

  11. Possible Climatic Signal Recorded by Alkenone Distributions in Sediments from Freshwater and Saline Lakes on the Skarvsnes and Skallen Areas, Antarctica

    NASA Astrophysics Data System (ADS)

    Sawada, K.; Takeda, M.; Takano, Y.

    2014-12-01

    The distribution of long-chain (C37 - C39) alkenones in marine sediment has been well documented to record paleo-sea surface temperatures. The alkenones were also found in sediments of terrestrial saline lakes, and recently the calibrations of alkenone unsaturation indices - temperature have been established in continental areas. Furthermore, these biomarkers have been identified in lacustrine sediments on high-latitudinal terrestrial areas such as Greenland and Antarctica. In the present study, the alkenones were identified in the lacustrine sediment cores in freshwater (Lake Naga-ike) and saline lakes (Lake Suribati and Lake Funazoko) on the Skarvsnes, and a saline lake (Lake Skallen Oh-ike) on the Skallen, Antarctica. Here, we report that the alkenone distribution in the Antarctic lakes was examined as paleotemperature proxy. C37-C38 Tetra- and tri-unsaturated alkenones and C37 tetra- and tri-unsaturated alkenoates are identified in all sediment samples. The C37 di-unsaturated (C37:2) alkenones can be identified in sediments of surface layers (0-15 cm) of Lake Naga-ike and layers of 160-190 cm depth, in which age is ca. 3000 years BP by 14C dating, in Lake Skallen Ohike, and alkenone unsaturation index (UK37) is analyzed from these sediments. By using a calibration obtained from a culture strain Chrysotila lamellosa as reported by Nakamura et al. (2014), paleotemperatures are calculated to be 9.2-15ºC in surface sediments of Lake Naga-ike and 6.8-8.6ºC in Lake Skallen Oh-ike, respectively. The estimated temperatures are concordant with summer temperature of lake waters observed in Lake Naga-ike. Also, the highest concentrations of the alkenones and alkenoates are observed in deeper (older) sediment layers from Lake Naga-ikes, which has not been connected the ocean and intruded sea water. This implies that the alkenones are originated from indigenous biological organism(s) in Antarctic lake water. The class distributions (unsaturation ratios) of alkenones

  12. Suspended-sediment and fresh-water discharges in the Ob and Yenisey rivers, 1960-1988

    USGS Publications Warehouse

    Meade, R.H.; Bobrovitskaya, N.N.; Babkin, V.I.

    2000-01-01

    Of the world's great rivers, the Ob and Yenisey rank among the largest suppliers of fresh water and among the smallest suppliers of suspended sediment to the coastal ocean. Sediment in the middle reaches of the rivers is mobilized from bordering terraces and exchanged between channels and flood plains. Sediment in the lower reaches of these great rivers is deposited and stored (permanently, on a millennial time scale) in flood plains. Sediment discharges, already small under natural conditions, are diminished further by large manmade reservoirs that trap significant proportions of the moving solids. The long winter freeze and sudden spring breakup impose a peakedness in seasonal water runoff and sediment discharge that contrasts markedly with that in rivers of the tropics and more temperate climates. Very little sediment from the Ob and Yenisey rivers is being transported to the open waters of the Arctic Ocean under present conditions.

  13. A comparison of equilibrium partitioning and critical body residue approaches for predicting toxicity of sediment-associated fluoranthene to freshwater amphipods

    SciTech Connect

    Driscoll, S.K.; Landrum, P.F.

    1997-10-01

    Equilibrium partitioning (EqP) theory predicts that the effects of organic compounds in sediments can be assessed by comparison of organic carbon-normalized sediment concentrations and estimated pore-water concentrations to effects determined in water-only exposures. A complementary approach, the critical body residue (CBR) theory, examines actual body burdens in relation to toxic effects. Critical body residue theory predicts that the narcotic effects of nonpolar compounds should be essentially constant for similar organisms, and narcosis should be observed at body burdens of 2 to 8 {micro}mol/g tissue. This study compares these two approaches for predicting toxicity of the polycyclic aromatic hydrocarbon (PAH) fluoranthene. The freshwater amphipods Hyalella azteca and Diporeia spp. were exposed for up to 30 d to sediment spiked with radiolabeled fluoranthene at concentrations of 0.1 (trace) to 3.940 nmol/g dry weight (= 346 {micro}mol/g organic carbon). Mean survival of Diporeia was generally high (>70%) and not significantly different from that of control animals. This result agrees with EqP predictions, because little mortality was observed for Diporeia in 10-d water-only exposures to fluoranthene in previous studies. After 10-d exposures, mortality of H. azteca was not significantly different from that of controls, even though measured interstitial water concentrations exceeded the previously determined 10-d water-only median lethal concentration (LC50). Equilibrium partitioning overpredicted fluoranthene sediment toxicity in this species. More mortality was observed for H. azteca at later time points, and a 16-d LC50 of 3.550 nmol/g dry weight sediment (291 {micro}mol/g organic carbon) was determined. A body burden of 1.10 {micro}mol fluoranthene-equivalents/g wet weight in H. azteca was associated with 50% mortality after 16-d exposures. Body burdens as high as 5.9 {micro}mol/g wet weight resulted in little mortality in Diporeia.

  14. Sources of suspended-sediment loads in the lower Nueces River watershed, downstream from Lake Corpus Christi to the Nueces Estuary, south Texas, 1958–2010

    USGS Publications Warehouse

    Ockerman, Darwin J.; Heitmuller, Franklin T.; Wehmeyer, Loren L.

    2013-01-01

    The HSPF model was calibrated to simulate suspended sediment using suspended-sediment data collected at the Mathis, Bluntzer, and Calallen gages during 2006-7. Model simulated suspended-sediment loads at the Calallen gage were within 5 percent of loads that were estimated, by regression, from suspended-sediment sample analysis and measured streamflow. The calibrated watershed model was used to estimate streamflow and suspended-sediment loads for 1958-2010, including loads transported to the Nueces Estuary. During 1958-2010, on average, an estimated 288 tons per day (tons/d) of suspended sediment were delivered to the lower Nueces River; an estimated 278 tons/d were delivered to the estuary. The annual suspended-sediment load was highly variable, depending on the occurrence of runoff events and high streamflows. During 1958-2010, the annual total sediment loads to the estuary varied from an estimated 3.8 to 2,490 tons/d. On average, 113 tons/d, or about 39 percent of the estimated annual suspended-sediment contribution, originated from cropland in the study watershed. Releases from Lake Corpus Christi delivered an estimated 94 tons/d of suspended sediment or about 33 percent of the 288 tons/d estimated to have been delivered to the lower Nueces River. Erosion of stream-channel bed and banks accou

  15. Extracting Length and Time Scales of Downstream Suspended Transport from Sediment Budget Data: ~100 to 1000-yr Travel Times from the Appalachians to the Chesapeake Bay, U.S.A

    NASA Astrophysics Data System (ADS)

    Pizzuto, J. E.; Schenk, E.; Hupp, C. R.; Gellis, A.; Noe, G. B.; Williamson, E.; Karwan, D. L.; O'Neal, M. A.; Marquard, J.; Aalto, R. E.; Newbold, J. D.

    2013-12-01

    Watershed Best Management Practices (BMPs) are often designed to reduce loadings of sediments and particle-borne contaminants, but the temporal lag between BMP implementation and improvement in receiving water quality is difficult to assess because particles spend long periods in storage between transport events. Here we present a theory that describes the downstream movement of suspended sediment particles accounting for the time particles spend in storage based on sediment budget data (by grain-size fraction) and information on particle transit times through storage reservoirs. The theory is used to define a suspended-sediment transport-length scale that describes how far particles are carried during transport events, and to estimate a downstream particle velocity that includes time spent in storage. At five upland watersheds of the mid-Atlantic region of the U.S.A., transport-length scales for silt-clay range from 3.5-76.1 km, while those for sand range from 0.9-139.6 km. Stratigraphic data and radiometric dating for a typical eroding bank section suggest an averaged sediment transit time through floodplain storage of 488 years. Mean sediment velocities for silt-clay range from 0.0072-0.16 km/yr, while those for sand range from 0.0008-0.25 km/yr, 4 to 6 orders of magnitude slower than the velocity of water in the channel. These results suggest lag times of 100-1000 years between BMP implementation and effectiveness in receiving waters such as the Chesapeake Bay (where BMPs are located upstream of the characteristic transport length scale). Many particles likely travel much faster than these average values, so further research is needed to define the range and distribution of transport rates within and across particle sizes.

  16. The adsorption/desorption of phosphorus in freshwater sediments from buffer zones: the effects of sediment concentration and pH.

    PubMed

    Zhang, Liang; Du, Yun; Du, Chao; Xu, Meng; Loáiciga, Hugo A

    2016-01-01

    Riparian buffer zones adjacent to reservoirs and lakes protect aquatic ecosystems from polluted surface runoff. Sediments, collected from the buffer zones of Danjiangkou Reservoir (SR) and Honghu Lake (SL) in an ecologically fragile region in central China, were evaluated to reveal their phosphorus-adsorbing/desorbing properties and storage capacities. A nonlinear regression method was used to fit the pseudo-second-order kinetic and the modified crossover-type Langmuir isotherm models to the experimental data. It is shown that the adsorption of phosphorus onto the studied sediments followed the pseudo-second-order kinetic expression. The modified crossover-type Langmuir isotherm model was found to be a suitable method for describing adsorption/desorption processes in the experimental sediments. The maximum adsorption capacities (Q m), partitioning coefficients (K p), native adsorbed exchangeable phosphorus (NAP), and equilibrium phosphorus concentration (EPC0) were subsequently obtained for the experimental sediments. The effects of sediment concentration and pH were also investigated by batch experiments and Fourier transformation infrared and scanning electron microscopy analyses. The adsorption/desorption characteristics of different phosphate species on the sediments from reservoir and lake buffer zones were identified.

  17. REQUEST FOR APPLICATIONS: THE ROLE OF SEDIMENTS IN THE TRANSPORT AND FATE OF POLLUTANTS IN FRESHWATER AND ESTUARIES

    EPA Science Inventory

    This is a request for grant applications to conduct research on the physical, chemical and biological processes controlling contaminant transport and transformation near the sediment-water interface of aquatic systems. It is believed that pollutants previously deposited in botto...

  18. A Sediment Budget Case Study: Comparing Watershed Scale Erosion Estimates to Modeled and Empirical Sediment Loads

    NASA Astrophysics Data System (ADS)

    McDavitt, B.; O'Connor, M.

    2003-12-01

    The Pacific Lumber Company Habitat Conservation Plan requires watershed analyses to be conducted on their property. This paper summarizes a portion of that analysis focusing on erosion and sedimentation processes and rates coupled with downstream sediment routing in the Freshwater Creek watershed in northwest California. Watershed scale erosion sources from hillslopes, roads, and channel banks were quantified using field surveys, aerial photo interpretation, and empirical modeling approaches for different elements of the study. Sediment transport rates for bedload were modeled, and sediment transport rates for suspended sediment were estimated based on size distribution of sediment inputs in relation to sizes transported in suspension. Recent short-term, high-quality estimates of suspended sediment yield that a community watershed group collected with technical assistance from the US Forest Service were used to validate the resulting sediment budget. Bedload yield data from an adjacent watershed, Jacoby Creek, provided another check on the sediment budget. The sediment budget techniques and bedload routing models used for this study generated sediment yield estimates that are in good agreement with available data. These results suggest that sediment budget techniques that require moderate levels of fieldwork can be used to provide relatively accurate technical assessments. Ongoing monitoring of sediment sources coupled with sediment routing models and reach scale field data allows for predictions to be made regarding in-channel sediment storage.

  19. Oxygen and phosphorus dynamics in freshwater sediment after the deposition of flocculated cyanobacteria and the role of tubificid worms.

    PubMed

    Zhang, Lei; Liao, Qianjiahua; Gu, Xiaozhi; He, Wei; Zhang, Zhe; Fan, Chengxin

    2014-02-15

    Flocculation is a promising method for controlling harmful algal blooms; however, little is known about the effects of algae deposition by flocculation on benthic oxygen (O2) and nutrient dynamics. In this study, we aimed to investigate the influence of cyanobacteria flocculation deposition on benthic O2 and phosphorus (P) dynamics and the role of tubificid worms in the process. Chitosan and sediment particles were used to flocculate and deposit cyanobacteria cells onto lake sediment. The impulse deposition of algal flocculation degraded the deposited algal cells, which decreased the O2 penetration depth in sediment and increased the O2 uptake rate. Algae deposition also increased the soluble reactive P (SRP) in pore water and loosely adsorbed P in sediment, and changed SRP flux. Tubificid worms transported algal cells deeper into the sediment, mitigated their degradation, and altered the O2 penetration depth, but not the O2 uptake rate. Tubificid worms enhanced the increase in pore-water SRP and loosely adsorbed P in sediment. Therefore, the deposition of algal flocculation modifies the benthic O2 and P dynamics, and tubificid worms can mitigate or enhance some of these processes.

  20. Accumulation of clinically relevant antibiotic-resistance genes, bacterial load, and metals in freshwater lake sediments in Central Europe.

    PubMed

    Devarajan, Naresh; Laffite, Amandine; Graham, Neil D; Meijer, Maria; Prabakar, Kandasamy; Mubedi, Josué I; Elongo, Vicky; Mpiana, Pius T; Ibelings, Bastiaan Willem; Wildi, Walter; Poté, John

    2015-06-01

    Wastewater treatment plants (WWTP) receive the effluents from various sources (communities, industrial, and hospital effluents) and are recognized as reservoir for antibiotic-resistance genes (ARGs) that are associated with clinical pathogens. The aquatic environment is considered a hot-spot for horizontal gene transfer, and lake sediments offer the opportunity for reconstructing the pollution history and evaluating the impacts. In this context, variation with depth and time of the total bacterial load, the abundance of faecal indicator bacteria (FIB; E. coli and Enterococcus spp. (ENT)), Pseudomonas spp., and ARGs (blaTEM, blaSHV, blaCTX-M, blaNDM, and aadA) were quantified in sediment profiles of different parts of Lake Geneva using quantitative PCR. The abundance of bacterial marker genes was identified in sediments contaminated by WWTP following eutrophication of the lake. Additionally, ARGs, including the extended-spectrum ß-lactam- and aminoglycoside-resistance genes, were identified in the surface sediments. The ARG and FIB abundance strongly correlated (r ≥ 0.403, p < 0.05, n = 34) with organic matter and metal concentrations in the sediments, indicating a common and contemporary source of contamination. The contamination of sediments by untreated or partially treated effluent water can affect the quality of ecosystem. Therefore, the reduction of contaminants from the source is recommended for further improvement of water quality. PMID:25933054

  1. Sources of suspended-sediment loads in the lower Nueces River watershed, downstream from Lake Corpus Christi to the Nueces Estuary, south Texas, 1958–2010

    USGS Publications Warehouse

    Ockerman, Darwin J.; Heitmuller, Franklin T.; Wehmeyer, Loren L.

    2013-01-01

    During 2010, additional suspended-sediment data were collected during selected runoff events to provide new data for model testing and to help better understand the sources of suspended-sediment loads. The model was updated and used to estimate and compare sediment yields from each of 64 subwatersheds comprising the lower Nueces River watershed study area for three selected runoff events: November 20-21, 2009, September 7-8, 2010, and September 20-21, 2010. These three runoff events were characterized by heavy rainfall centered near the study area and during which minimal streamflow and suspended-sediment load entered the lower Nueces River upstream from Wesley E. Seale Dam. During all three runoff events, model simulations showed that the greatest sediment yields originated from the subwatersheds, which were largely cropland. In particular, the Bayou Creek subwatersheds were major contributors of suspended-sediment load to the lower Nueces River during the selected runoff events. During the November 2009 runoff event, high suspended-sediment concentrations in the Nueces River water withdrawn for the City of Corpus Christi public-water supply caused problems during the water-treatment process, resulting in failure to meet State water-treatment standards for turbidity in drinking water. Model simulations of the November 2009 runoff event showed that the Bayou Creek subwatersheds were the primary source of suspended-sediment loads during that runoff event.

  2. Simulation of streamflow and suspended-sediment concentrations and loads in the lower Nueces River watershed, downstream from Lake Corpus Christi to the Nueces Estuary, South Texas, 1958-2008

    USGS Publications Warehouse

    Ockerman, Darwin J.; Heitmuller, Franklin T.

    2010-01-01

    The U.S. Geological Survey (USGS), in cooperation with the U.S. Army Corps of Engineers-Fort Worth District, City of Corpus Christi, Guadalupe-Blanco River Authority, San Antonio River Authority, and San Antonio Water System, developed, calibrated, and tested a Hydrological Simulation Program ? FORTRAN (HSPF) watershed model to simulate streamflow and suspended-sediment concentrations and loads during 1958-2008 in the lower Nueces River watershed, downstream from Lake Corpus Christi to the Nueces Estuary in South Texas. Data available to simulate suspended-sediment concentrations and loads consisted of historical sediment data collected during 1942-82 in the study area and suspended-sediment concentration data collected periodically by the USGS during 2006-07 at three USGS streamflow-gaging stations, Nueces River near Mathis, Nueces River at Bluntzer, and Nueces River at Calallen. The Nueces River near Mathis station is downstream from Wesley E. Seale Dam, completed in 1958 to impound Lake Corpus Christi. Suspended-sediment data collected before and after completion of Wesley E. Seale Dam provide insights to the effects of the dam and reservoir on suspended-sediment loads transported by the lower Nueces River from downstream of the dam to the Nueces Estuary. Annual suspended-sediment loads at a site near the Nueces River at Mathis station were considerably lower, for a given annual mean discharge, after the dam was completed than before the dam was completed. Most of the suspended sediment transported by the Nueces River downstream from Wesley E. Seale Dam occurred during high-flow releases from the dam or during floods. During October 1964-September 1971, about 532,000 tons of suspended sediment were transported by the Nueces River near Mathis. Of this amount, about 473,000 tons, or about 89 percent, were transported by large runoff events (mean streamflow exceeding 1,000 cubic feet per second). To develop the watershed model to simulate suspended-sediment

  3. Improving sediment-quality guidelines for nickel: development and application of predictive bioavailability models to assess chronic toxicity of nickel in freshwater sediments.

    PubMed

    Vangheluwe, Marnix L U; Verdonck, Frederik A M; Besser, John M; Brumbaugh, William G; Ingersoll, Christopher G; Schlekat, Christan E; Garman, Emily Rogevich

    2013-11-01

    Within the framework of European Union chemical legislations an extensive data set on the chronic toxicity of sediment nickel has been generated. In the initial phase of testing, tests were conducted with 8 taxa of benthic invertebrates in 2 nickel-spiked sediments, including 1 reasonable worst-case sediment with low concentrations of acid-volatile sulfide (AVS) and total organic carbon. The following species were tested: amphipods (Hyalella azteca, Gammarus pseudolimnaeus), mayflies (Hexagenia sp.), oligochaetes (Tubifex tubifex, Lumbriculus variegatus), mussels (Lampsilis siliquoidea), and midges (Chironomus dilutus, Chironomus riparius). In the second phase, tests were conducted with the most sensitive species in 6 additional spiked sediments, thus generating chronic toxicity data for a total of 8 nickel-spiked sediments. A species sensitivity distribution was elaborated based on 10% effective concentrations yielding a threshold value of 94 mg Ni/kg dry weight under reasonable worst-case conditions. Data from all sediments were used to model predictive bioavailability relationships between chronic toxicity thresholds (20% effective concentrations) and AVS and Fe, and these models were used to derive site-specific sediment-quality criteria. Normalization of toxicity values reduced the intersediment variability in toxicity values significantly for the amphipod species Hyalella azteca and G. pseudolimnaeus, but these relationships were less clearly defined for the mayfly Hexagenia sp. Application of the models to prevailing local conditions resulted in threshold values ranging from 126 mg to 281 mg Ni/kg dry weight, based on the AVS model, and 143 mg to 265 mg Ni/kg dry weight, based on the Fe model. PMID:23983116

  4. Improving sediment-quality guidelines for nickel: development and application of predictive bioavailability models to assess chronic toxicity of nickel in freshwater sediments

    USGS Publications Warehouse

    Vangheluwe, Marnix L. U.; Verdonck, Frederik A. M.; Besser, John M.; Brumbaugh, William G.; Ingersoll, Christopher G.; Schlekat, Christan E.; Rogevich Garman, Emily

    2013-01-01

    Within the framework of European Union chemical legislations an extensive data set on the chronic toxicity of sediment nickel has been generated. In the initial phase of testing, tests were conducted with 8 taxa of benthic invertebrates in 2 nickel-spiked sediments, including 1 reasonable worst-case sediment with low concentrations of acid-volatile sulfide (AVS) and total organic carbon. The following species were tested: amphipods (Hyalella azteca, Gammarus pseudolimnaeus), mayflies (Hexagenia sp.), oligochaetes (Tubifex tubifex, Lumbriculus variegatus), mussels (Lampsilis siliquoidea), and midges (Chironomus dilutus, Chironomus riparius). In the second phase, tests were conducted with the most sensitive species in 6 additional spiked sediments, thus generating chronic toxicity data for a total of 8 nickel-spiked sediments. A species sensitivity distribution was elaborated based on 10% effective concentrations yielding a threshold value of 94 mg Ni/kg dry weight under reasonable worst-case conditions. Data from all sediments were used to model predictive bioavailability relationships between chronic toxicity thresholds (20% effective concentrations) and AVS and Fe, and these models were used to derive site-specific sediment-quality criteria. Normalization of toxicity values reduced the intersediment variability in toxicity values significantly for the amphipod species Hyalella azteca and G. pseudolimnaeus, but these relationships were less clearly defined for the mayfly Hexagenia sp. Application of the models to prevailing local conditions resulted in threshold values ranging from 126 mg to 281 mg Ni/kg dry weight, based on the AVS model, and 143 mg to 265 mg Ni/kg dry weight, based on the Fe model

  5. Improving sediment-quality guidelines for nickel: development and application of predictive bioavailability models to assess chronic toxicity of nickel in freshwater sediments.

    PubMed

    Vangheluwe, Marnix L U; Verdonck, Frederik A M; Besser, John M; Brumbaugh, William G; Ingersoll, Christopher G; Schlekat, Christan E; Garman, Emily Rogevich

    2013-11-01

    Within the framework of European Union chemical legislations an extensive data set on the chronic toxicity of sediment nickel has been generated. In the initial phase of testing, tests were conducted with 8 taxa of benthic invertebrates in 2 nickel-spiked sediments, including 1 reasonable worst-case sediment with low concentrations of acid-volatile sulfide (AVS) and total organic carbon. The following species were tested: amphipods (Hyalella azteca, Gammarus pseudolimnaeus), mayflies (Hexagenia sp.), oligochaetes (Tubifex tubifex, Lumbriculus variegatus), mussels (Lampsilis siliquoidea), and midges (Chironomus dilutus, Chironomus riparius). In the second phase, tests were conducted with the most sensitive species in 6 additional spiked sediments, thus generating chronic toxicity data for a total of 8 nickel-spiked sediments. A species sensitivity distribution was elaborated based on 10% effective concentrations yielding a threshold value of 94 mg Ni/kg dry weight under reasonable worst-case conditions. Data from all sediments were used to model predictive bioavailability relationships between chronic toxicity thresholds (20% effective concentrations) and AVS and Fe, and these models were used to derive site-specific sediment-quality criteria. Normalization of toxicity values reduced the intersediment variability in toxicity values significantly for the amphipod species Hyalella azteca and G. pseudolimnaeus, but these relationships were less clearly defined for the mayfly Hexagenia sp. Application of the models to prevailing local conditions resulted in threshold values ranging from 126 mg to 281 mg Ni/kg dry weight, based on the AVS model, and 143 mg to 265 mg Ni/kg dry weight, based on the Fe model.

  6. Microbial Iron(II) Oxidation in Littoral Freshwater Lake Sediment: The Potential for Competition between Phototrophic vs. Nitrate-Reducing Iron(II)-Oxidizers

    PubMed Central

    Melton, E. D.; Schmidt, C.; Kappler, A.

    2012-01-01

    The distribution of neutrophilic microbial iron oxidation is mainly determined by local gradients of oxygen, light, nitrate and ferrous iron. In the anoxic top part of littoral freshwater lake sediment, nitrate-reducing and phototrophic Fe(II)-oxidizers compete for the same e− donor; reduced iron. It is not yet understood how these microbes co-exist in the sediment and what role they play in the Fe cycle. We show that both metabolic types of anaerobic Fe(II)-oxidizing microorganisms are present in the same sediment layer directly beneath the oxic-anoxic sediment interface. The photoferrotrophic most probable number counted 3.4·105 cells·g−1 and the autotrophic and mixotrophic nitrate-reducing Fe(II)-oxidizers totaled 1.8·104 and 4.5·104 cells·g−1 dry weight sediment, respectively. To distinguish between the two microbial Fe(II) oxidation processes and assess their individual contribution to the sedimentary Fe cycle, littoral lake sediment was incubated in microcosm experiments. Nitrate-reducing Fe(II)-oxidizing bacteria exhibited a higher maximum Fe(II) oxidation rate per cell, in both pure cultures and microcosms, than photoferrotrophs. In microcosms, photoferrotrophs instantly started oxidizing Fe(II), whilst nitrate-reducing Fe(II)-oxidizers showed a significant lag-phase during which they probably use organics as e− donor before initiating Fe(II) oxidation. This suggests that they will be outcompeted by phototrophic Fe(II)-oxidizers during optimal light conditions; as phototrophs deplete Fe(II) before nitrate-reducing Fe(II)-oxidizers start Fe(II) oxidation. Thus, the co-existence of the two anaerobic Fe(II)-oxidizers may be possible due to a niche space separation in time by the day-night cycle, where nitrate-reducing Fe(II)-oxidizers oxidize Fe(II) during darkness and phototrophs play a dominant role in Fe(II) oxidation during daylight. Furthermore, metabolic flexibility of Fe(II)-oxidizing microbes may play a paramount role in the

  7. Biogeochemical factors influencing net mercury methylation in contaminated freshwater sediments from the St. Lawrence River in Cornwall, Ontario, Canada.

    PubMed

    Avramescu, Mary-Luyza; Yumvihoze, Emmanuel; Hintelmann, Holger; Ridal, Jeff; Fortin, Danielle; Lean, David R S

    2011-02-01

    The activity of various anaerobic microbes, including sulfate reducers (SRB), iron reducers (FeRP) and methanogens (MPA) has been linked to mercury methylation in aquatic systems, although the relative importance of each microbial group in the overall process is poorly understood in natural sediments. The present study focused on the biogeochemical factors (i.e. the relative importance of various groups of anaerobic microbes (FeRP, SRB, and MPA) that affect net monomethylmercury (MMHg) formation in contaminated sediments of the St. Lawrence River (SRL) near Cornwall (Zone 1), Ontario, Canada. Methylation and demethylation potentials were measured separately by using isotope-enriched mercury species ((200)Hg(2+) and MM(199)Hg(+)) in sediment microcosms treated with specific microbial inhibitors. Sediments were sampled and incubated in the dark at room temperature in an anaerobic chamber for 96h. The potential methylation rate constants (K(m)) and demethylation rates (K(d)) were found to differ significantly between microcosms. The MPA-inhibited microcosm had the highest potential methylation rate constant (0.016d(-1)), whereas the two SRB-inhibited microcosms had comparable potential methylation rate constants (0.003d(-1) and 0.002d(-1), respectively). The inhibition of methanogens stimulated net methylation by inhibiting demethylationand by stimulating methylation along with SRB activity. The inhibition of both methanogens and SRB was found to enhance the iron reduction rates but did not completely stop MMHg production. The strong positive correlation between K(m) and Sulfate Reduction Rates (SRR) and between K(d) and Methane Production Rates (MPR) supports the involvement of SRB in Hg methylation and MPA in MMHg demethylation in the sediments. In contrast, the strong negative correlation between K(d) and Iron Reduction Rates (FeRR) shows that the increase in FeRR corresponds to a decrease in demethylation, indicating that iron reduction may influence net

  8. Simultaneous determination of organotin pesticides by HPLC-ICP-MS and their sorption, desorption, and transformation in freshwater sediments.

    PubMed

    Gui, Wenjun; Tian, Chunxia; Sun, Qianqian; Li, Shuying; Zhang, Wei; Tang, Jun; Zhu, Guonian

    2016-05-15

    In order to better assess their environmental risks, the sorption and degradation of triphenyltin hydroxide, azocyclotin and fenbutatin oxide were studied in two sediments under varying laboratory conditions in this study. An analytical method for simultaneous determination of the three organotins in environmental samples was firstly developed using high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). The limit of detection and limit of quantification for standards ranged from 0.13 to 1.46 μg/L. Fortification study showed that when spiked at 2-250 μg/kg the mass recoveries were 73.7-119.6%. Sorption isotherm experiments indicated that the organotins could be strongly adsorbed by the sediments, and organotin sorption kinetics obeyed the pseudo second-order kinetic model. The sorption affinity was inversely related to their water solubility. All isotherms fitted with the Henry mode fairly well (r(2) > 0.96) with distribution coefficients (Kd) ranging from 746.1 to 2465.2 mL/g. The three organotins could rapidly move from the upper water layer to the lower sediment layer, and they were all of moderate degradation compounds with the degradation half lives varying from 38.3 to 84.5d in anaerobic and aerobic water-sediment systems. The degradation rate seemed to be positively related to organic matter content of sediment. Result inferred that the three organotins had the low risks to pollute groundwater when applied on dry land and could moderately degrade in water-sediment system. However, more attention should still be paid to these organotins due to the wide application on agricultural field. PMID:26994697

  9. Development of rearing and testing protocols for a new freshwater sediment test species: the gastropod Valvata piscinalis.

    PubMed

    Ducrot, Virginie; Cognat, Claudine; Mons, Raphaël; Mouthon, Jacques; Garric, Jeanne

    2006-03-01

    This paper aimed at proposing rearing and testing protocols for Valvata piscinalis, a new potential species for sediment toxicity testing. Such tests were developed since this species reliably represents the bio/ecological characteristics of other gastropods. It may thus be representative of their sensitivity to chemicals. V. piscinalis was successfully cultured in our laboratory for six generations. Cultures provided a high productivity for a low working time and low costs. The tests conditions we proposed seemed to be relevant for the development of reliable tests with this species. Indeed, hatching probability of egg-capsules, as well as embryo, newborn and juvenile survival rates, were close to 100%. Moreover, growth rates and fecundity were significantly higher than in field and in other laboratory studies. Partial life-cycle tests on clean sediments were achieved for various feeding levels to determine survival, growth and reproduction patterns, ad libitum feeding level and life cycle parameters values. Ad libitum feeding levels for newborn, juveniles and adults were 0.1, 0.4 and 0.8 mg Tetramin/individual/working day. Growth tests with zinc-spiked sediments provided a no-effect concentration and a lowest effect concentration of respectively 200 and 624 mg zinc/kg dry sediment. Other growth tests on spiked sediments we ran at our laboratory with second, third and fourth instars larvae of Chironomus riparius pointed out that V. piscinalis was more sensible to zinc than the chironomid, which is a routine test species in ecotoxicology. According to these results, V. piscinalis is a promising candidate species for sediment toxicity testing.

  10. CRITICAL BODY RESIDUES FOR FRESHWATER AND SALTWATER AMPHIPODS EXPOSED TO SEDIMENT CONTAINING A MIXTURE OF HIGH KOW PAHS

    EPA Science Inventory

    Sediments were spiked with a mixture of 13 high log Kow (5.4-6.8) PAH compounds to determine critical body residues (CBR) in Hyalella azteca and Leptocheirus plumulosus. Hyalella were exposed for 28 d in a intermittent flow test and for 10 d in a static test to compare PAH uptake...

  11. Simulation of hydrologic conditions and suspended-sediment loads in the San Antonio River Basin downstream from San Antonio, Texas, 2000-12

    USGS Publications Warehouse

    Banta, J. Ryan; Ockerman, Darwin J.

    2014-01-01

    Suspended sediment in rivers and streams can play an important role in ecological health of rivers and estuaries and consequently is an important issue for water-resource managers. To better understand suspended-sediment loads and transport in a watershed, the U.S. Geological Survey (USGS), in cooperation with the San Antonio River Authority, developed a Hydrological Simulation Program—FORTRAN model to simulate hydrologic conditions and suspended-sediment loads during 2000–12 for four watersheds, which comprise the overall study area in the San Antonio River Basin (hereinafter referred to as the “USGS–2014 model”). The study area consists of approximately 2,150 square miles encompassing parts of Bexar, Guadalupe, Wilson, Karnes, DeWitt, Goliad, Victoria, and Refugio Counties. The USGS–2014 model was calibrated for hydrology and suspended sediment for 2006–12. Overall, model-fit statistics and graphic evaluations from the calibration and testing periods provided multiple lines of evidence indicating that the USGS–2014 model simulations of hydrologic and suspended-sediment conditions were mostly “good” to “very good.” Model simulation results indicated that approximately 1,230 tons per day of suspended sediment exited the study area and were delivered to the Guadalupe River during 2006–12, of which approximately 62 percent originated upstream from the study area. Sample data and simulated model results indicate that most of the suspended-sediment load in the study area consisted of silt- and clay-sized particles (less than 0.0625 millimeters). The Cibolo Creek watershed was the largest contributor of suspended sediment from the study area. For the entire study area, open/developed land and cropland exhibited the highest simulated soil erosion rates; however, the largest contributions of sediment (by land-cover type) were pasture and forest/rangeland/shrubland, which together composed approximately 80 percent of the land cover of the

  12. Development and application of an innovative expert decision support system to manage sediments and to assess environmental risk in freshwater ecosystems.

    PubMed

    Dagnino, Alessandro; Bo, Tiziano; Copetta, Andrea; Fenoglio, Stefano; Oliveri, Caterina; Bencivenga, Mauro; Felli, Angelo; Viarengo, Aldo

    2013-10-01

    With the aim of supporting decision makers to manage contamination in freshwater environments, an innovative expert decision support system (EDSS) was developed. The EDSS was applied in a sediment quality assessment along the Bormida river (NW, Italy) which has been heavily contaminated by an upstream industrial site for more than a century. Sampling sites were classified by means of comparing chemical concentrations with effect-based target values (threshold and probable effect concentrations). The level of each contaminant and the combined toxic pressure were used to rank sites into three categories: (i) uncontaminated (8 sites), (ii) mildly contaminated (4) and (iii) heavily contaminated (19). In heavily contaminated sediments, an environmental risk index (EnvRI) was determined by means of integrating chemical data with ecotoxicological and ecological parameters (triad approach). In addition a sediment risk index (SedRI) was computed from combining chemical and ecotoxicological data. Eight sites exhibited EnvRI values ≥0.25, the safety threshold level (range of EnvRI values: 0.14-0.31) whereas SedRI exceeded the safety threshold level at 6 sites (range of SedRI values: 0.16-0.36). At sites classified as mildly contaminated, sublethal biomarkers were integrated with chemical data into a biological vulnerability index (BVI), which exceeded the safety threshold level at one site (BVI value: 0.28). Finally, potential human risk was assessed in selected stations (11 sites) by integrating genotoxicity biomarkers (GTI index falling in the range 0.00-0.53). General conclusions drawn from the EDSS data include: (i) in sites classified as heavily contaminated, only a few exhibited some significant, yet limited, effects on biodiversity; (ii) restrictions in re-using sediments from heavily contaminated sites found little support in ecotoxicological data; (iii) in the majority of the sites classified as mildly contaminated, tested organisms exhibited low response levels

  13. Impacts of large dams on downstream fluvial sedimentation: An example of the Three Gorges Dam (TGD) on the Changjiang (Yangtze River)

    NASA Astrophysics Data System (ADS)

    Dai, Zhijun; Liu, James T.

    2013-02-01

    SummaryUnder the influence of climate and human activities, fluvial systems have natural ability to make adjustments so that the river hydrology, sediment movement, and channel morphology are in dynamic equilibrium. Taking the Changjiang (Yangtze River) for example. In the early stages after the Three Gorges Dam (TGD) began operational ten years ago, the suspended sediment content (SSC) and fluxes in the middle and lower reaches of the river decreased noticeably. At present, they appear to be in a stable state on the decadal scale. Although the river runoff has not shown any trends, the water level in the river decreased appreciably in time. In the meantime, channel down cutting along the thalweg almost existed throughout the river course. The riverbed has turned from depositional before the dam construction to erosional afterwards. In other words, the riverbed had turned from being sediment sinks to sediment sources. In the main channel of the Changjiang between Yichang and Nanjing, a distance of 1300 km, the riverbed sedimentation mode displays strong, intermediate, and weak erosion depending on the closeness to the TGD.

  14. Effects of the pesticides captan, deltamethrin, isoproturon, and pirimicarb on the microbial community of a freshwater sediment.

    PubMed

    Widenfalk, Anneli; Svensson, Jonas M; Goedkoop, Willem

    2004-08-01

    In three microcosm experiments, we exposed microbial communities of a natural sediment to environmentally relevant concentrations of the fungicide captan, the herbicide isoproturon, and the insecticides deltamethrin and pirimicarb. Exposure concentrations were estimated negligible concentrations (NCs), maximum permissible concentrations (MPCs), and 100 times MPC (100MPC). Experimental endpoints were microbial community respiration and biomass, bacterial activity, and denitrification. All four pesticides inhibited bacterial activity by 20 to 24% at MPC, which corresponded to concentrations in the range of microg/kg dry-weight sediment. Treatments with deltamethrin and isoproturon showed inhibiting effects on bacterial activity at NC exposures. Surprisingly, for captan, deltamethrin, and isoproturon, this inhibiting effect was not observed at 100MPC treatments. Microbial biomass was negatively effected in MPC treatments with deltamethrin and in NC treatments with isoproturon. The tested pesticides did not affect community respiration and denitrification rates. These results show that exposure to the tested pesticides may induce toxic responses in sediment microbial communities at concentrations that are predicted to be environmentally safe.

  15. Ecology of tidal freshwater marshes of the United States east coast: a community profile

    SciTech Connect

    Odum, W.E.; Smith, T.J. III; Hoover, J.K.; McIvor, C.C.

    1984-01-01

    Tidal freshwater marshes are a distinctive type of estuarine ecosystem located upstream from tidal saline marshes and downstream from non-tidal freshwater marshes. They are characterized by freshwater or nearly freshwater conditions most of the time, flora and fauna dominated by freshwater species, and daily lunar tidal flushing. This report examines the ecology of this community as it occurs along the Atlantic seaboard from southern New England to northern Florida. This marsh community is heavily influenced by river flow, which maintains freshwater conditions and deposits sediments high in silt and clay. The plant assemblage in tidal freshwater marshes is diverse both in numbers of species and structural plant types. Plant community structure is markedly diverse spatially and seasonally, and reflects the dynamic processing of energy and biomass in the marsh through high productivity, rapid decomposition and seasonal nutrient cycling. The diverse niches in this heterogeneous environment are exploited by a very diverse animal community of as many as 125 species of fish, 102 species of amphibians and reptiles, 280 species of birds, and 46 species of mammals over the community's broad range. Although fewer species are permanent residents or marsh breeders, use of his community for food and cover is high. This use, coupled with the marshes' capacity to be natural buffers and water filters, argue for their high value as natural resources. 349 references, 31 figures, 24 tables.

  16. On the apparent failure of silt fences to protect freshwater ecosystems from sedimentation: A call for improvements in science, technology, training and compliance monitoring.

    PubMed

    Cooke, S J; Chapman, J M; Vermaire, J C

    2015-12-01

    Excessive sedimentation derived from anthropogenic activities is a main factor in habitat and biodiversity loss in freshwater ecosystems. To prevent offsite movement of soil particles, many environmental regulatory agencies mandate the use of perimeter silt fences. However, research regarding the efficiency of these devices in applied settings is lacking, and fences are often ineffective due to poor installation and maintenance. Here, we provide an overview of the current state of research regarding silt fences, address the current culture surrounding silt fence installation and maintenance, and provide several recommendations for improving the knowledge base related to silt fence effectiveness. It is clear that there is a need for integrated long-term (i.e., extending from prior to fence installation to well after fence removal) multi-disciplinary research with appropriate controls that evaluates the effectiveness of silt control fences. Through laboratory experiments, in silico modelling and field studies there are many factors that can be experimentally manipulated such as soil types (and sediment feed rate), precipitation regimes (and flow rate), season, slope, level of site disturbance, fence installation method, type of fence material, depth of toe, type and spacing of support structures, time since installation, level of inspection and maintenance, among others, that all require systematic evaluation. Doing so will inform the practice, as well as identify specific technical research needs, related to silt fence design and use. Moreover, what constitutes "proper" installation and maintenance is unclear, especially given regional- and site-level variation in precipitation, slope, and soil characteristics. Educating and empowering construction crews to be proactive in maintenance of silt fencing is needed given an apparent lack of compliance monitoring by regulatory agencies and the realities that the damage is almost instantaneous when silt fences fail. Our

  17. On the apparent failure of silt fences to protect freshwater ecosystems from sedimentation: A call for improvements in science, technology, training and compliance monitoring.

    PubMed

    Cooke, S J; Chapman, J M; Vermaire, J C

    2015-12-01

    Excessive sedimentation derived from anthropogenic activities is a main factor in habitat and biodiversity loss in freshwater ecosystems. To prevent offsite movement of soil particles, many environmental regulatory agencies mandate the use of perimeter silt fences. However, research regarding the efficiency of these devices in applied settings is lacking, and fences are often ineffective due to poor installation and maintenance. Here, we provide an overview of the current state of research regarding silt fences, address the current culture surrounding silt fence installation and maintenance, and provide several recommendations for improving the knowledge base related to silt fence effectiveness. It is clear that there is a need for integrated long-term (i.e., extending from prior to fence installation to well after fence removal) multi-disciplinary research with appropriate controls that evaluates the effectiveness of silt control fences. Through laboratory experiments, in silico modelling and field studies there are many factors that can be experimentally manipulated such as soil types (and sediment feed rate), precipitation regimes (and flow rate), season, slope, level of site disturbance, fence installation method, type of fence material, depth of toe, type and spacing of support structures, time since installation, level of inspection and maintenance, among others, that all require systematic evaluation. Doing so will inform the practice, as well as identify specific technical research needs, related to silt fence design and use. Moreover, what constitutes "proper" installation and maintenance is unclear, especially given regional- and site-level variation in precipitation, slope, and soil characteristics. Educating and empowering construction crews to be proactive in maintenance of silt fencing is needed given an apparent lack of compliance monitoring by regulatory agencies and the realities that the damage is almost instantaneous when silt fences fail. Our

  18. Lanthanide concentrations in freshwater plants and molluscs, related to those in surface water, pore water and sediment. A case study in The Netherlands.

    PubMed

    Weltje, Lennart; Heidenreich, Heike; Zhu, Wangzhao; Wolterbeek, Hubert Th; Korhammer, Siegfried; de Goeij, Jeroen J M; Markert, Bernd

    2002-03-01

    Industrial emissions of lanthanides to aquatic ecosystems increase, but knowledge of the environmental fate of these metals is limited. Here we focus attention upon the distribution of lanthanides in freshwater ecosystems, describing lanthanide partitioning between sediment, water and biota. Since lanthanides are often used as oxidation-state analogues for actinides, their distribution can reflect long-term behaviour of the radioactive transuranics. Concentrations of all 14 naturally occurring lanthanides were measured by ICP-MS in Sago pondweed (Potamogeton pectinatus), common duckweed (Lemna minor), seven different mollusc species (tissue and shell), two sediment fractions (< 2 mm and < 63 microm), surface water and sediment pore water from five locations in The Netherlands. In all samples, the typical 'saw-tooth' lanthanide pattern was observed, which implies that lanthanides are transported as a coherent group through aquatic ecosystems. Typical deviations from this pattern were found for Ce and Eu and could be explained by their redox chemistry. The variation in concentrations in abiotic fractions was limited, i.e. within one order of magnitude. However, variations of up to three orders of magnitude were observed in biotic samples, suggesting different affinities among organisms for lanthanides as a group, with significant differences only among molluscs and pondweed samples in relation to sampling location. For P. pectinatus it was shown that pore water was the most important lanthanide source, and for snails, food (plants) seems to be the dominant lanthanide source. Lanthanides were not equally distributed between mollusc shell and tissue and the ratio of lanthanide concentrations in shell and tissue were dependent on the sampling location. Shells contained much lower concentrations and were relatively enriched in Eu, and to a lesser extent in Ce. Bioconcentration factors for lanthanides in plants and snails relative to surface water were typically between

  19. Sediment Transport During Three Controlled-Flood Experiments on the Colorado River Downstream from Glen Canyon Dam, with Implications for Eddy-Sandbar Deposition in Grand Canyon National Park

    USGS Publications Warehouse

    Topping, David J.; Rubin, David M.; Grams, Paul E.; Griffiths, Ronald E.; Sabol, Thomas A.; Voichick, Nicholas; Tusso, Robert B.; Vanaman, Karen M.; McDonald, Richard R.

    2010-01-01

    Three large-scale field experiments were conducted on the Colorado River downstream from Glen Canyon Dam in 1996, 2004, and 2008 to evaluate whether artificial (that is, controlled) floods released from the dam could be used in conjunction with the sand supplied by downstream tributaries to rebuild and sustainably maintain eddy sandbars in the river in Grand Canyon National Park. Higher suspended-sand concentrations during a controlled flood will lead to greater eddy-sandbar deposition rates. During each controlled flood experiment, sediment-transport and bed-sediment data were collected to evaluate sediment-supply effects on sandbar deposition. Data collection substantially increased in spatial and temporal density with each subsequent experiment. The suspended- and bed-sediment data collected during all three controlled-flood experiments are presented and analyzed in this report. Analysis of these data indicate that in designing the hydrograph of a controlled flood that is optimized for sandbar deposition in a given reach of the Colorado River, both the magnitude and the grain size of the sand supply must be considered. Because of the opposing physical effects of bed-sand area and bed-sand grain size in regulating suspended-sand concentration, larger amounts of coarser sand on the bed can lead to lower suspended-sand concentrations, and thus lower rates of sandbar deposition, during a controlled flood than can lesser amounts of finer sand on the bed. Although suspended-sand concentrations were higher at all study sites during the 2008 controlled-flood experiment (CFE) than during either the 1996 or 2004 CFEs, these higher concentrations were likely associated with more sand on the bed of the Colorado River in only lower Glen Canyon. More sand was likely present on the bed of the river in Grand Canyon during the 1996 CFE than during either the 2004 or 2008 CFEs. The question still remains as to whether sandbars can be sustained in the Colorado River in Grand

  20. Diversity of Geobacteraceae species inhabiting metal-polluted freshwater lake sediments ascertained by 16S rDNA analyses.

    PubMed

    Cummings, D E; Snoeyenbos-West, O L; Newby, D T; Niggemyer, A M; Lovley, D R; Achenbach, L A; Rosenzweig, R F

    2003-08-01

    The abundance, distribution, and phylogenetic diversity of members of the Fe(III)-reducing family Geobacteraceae were studied along a gradient of metal contaminants in Lake Coeur d'Alene, Idaho. Partial 16S rRNA gene fragments were amplified by PCR using primers directed toward conserved regions of the gene within the family Geobacteraceae. Analysis of amplicons separated by denaturing gradient gel electrophoresis (DGGE) suggested within-site variation was as great as between-site variation. Amplicons were cloned and grouped by RFLP type and DGGE migration distance and representatives were sequenced. Grouping clones with 3% or less sequence dissimilarity, 15 distinct phylotypes were identified compared to 16 distinct DGGE bands. Only 1 phylotype was recovered from all sites. This clone, B14, is most closely related to Geobacter metallireducens and constituted a greater portion of the pristine community than of the contaminated communities. A second phylotype, Q2, predominated in the contaminated communities and was notably absent from the pristine libraries. Clone Q2 presents a high degree of sequence similarity to two Geobacter spp. previously isolated from this region of Lake Coeur d'Alene. Six phylotypes were unique to the contaminated sediments, whereas two were found only in the pristine sediments. Indices of diversity (Shannon and Simpson) were consistently higher when calculated with DGGE data than when clone library data were used. Most-probable-number PCR and real-time PCR suggested that the Geobacteraceae phylotypes were spread relatively evenly across all three sites along the gradient. Our data indicate that the Geobacteraceae are diverse and abundant in Lake Coeur d'Alene sediments, regardless of metals content. These results provide insight into the ability of dissimilatory Fe(III)-reducing bacteria to colonize habitats with elevated metal concentrations, and they have important implications for the management and remediation of metal

  1. Geochemical baselines of heavy metals in the sediments of two large freshwater lakes in China: implications for contamination character and history.

    PubMed

    Wei, Chaoyang; Wen, Hailong

    2012-12-01

    The aim of this study was to estimate the geochemical baseline concentrations of various heavy metals in the surface sediments of two large freshwater lakes in Taihu and Dianchi, China, and to assess the character and history of heavy metal contamination around the two lakes. Heavy metal concentrations in the sediments were obtained by field surveys and were supplemented with published data. The statistical methods of cumulative frequency and normalization were employed to obtain the baselines. The respective baseline concentrations for As, Sb, Hg, Co, Cr, Cu, Ni, Pb and Zn were 9.92, 1.67, 0.14, 22.62, 100.56, 31.63, 31.97, 33.05 and 97.01 mg/kg, respectively, in Taihu, and 24.60, 4.29, 0.25, 36.78, 135.68, 90.05, 50.76, 73.56 and 208.76 mg/kg, respectively, in Dianchi. The baseline concentrations of these heavy metals in Lake Taihu were equivalent to the pre-industrial concentrations determined from lakes in Sweden and Europe. Conversely, those in Lake Dianchi were much higher than the pre-industrial values. Li, Fe, Sc, Ti, V and Al were found to be the suitable reference elements for normalization, and one of these elements could be used to predict the baseline concentrations of heavy metals except Hg. Most of the heavy metals had one inflexion, and only Cu and Pb in Taihu, Sb, Pb and Zn in Dianchi, were found to have two inflexions in the cumulative curves, suggesting remarkable anthropogenic inputs of Cu and Pb in Taihu, Sb, Pb and Zn in Dianchi, which are generally consistent with the respective industrial structure around Taihu and Dianchi. PMID:23001472

  2. Bacillus stamsii sp. nov., a facultatively anaerobic sugar degrader that is numerically dominant in freshwater lake sediment.

    PubMed

    Müller, Nicolai; Scherag, Frank D; Pester, Michael; Schink, Bernhard

    2015-09-01

    A novel type of anaerobic bacteria was previously isolated from profundal lake sediment by direct dilution of the sediment in mineral agar medium containing glucose and a background lawn of Methanospirillum hungatei as a syntrophic partner. The isolated bacteria grouped with aerobic Bacillus spp. according to their 16S rRNA gene sequence, and the most closely related species is Bacillus thioparans. Fermentative growth of the novel strain with glucose was possible only in the presence of syntrophic partners, and cocultures produced acetate and methane, in some cases also lactate and traces of succinate as fermentation products. In contrast, the closely related strains Bacillus jeotgali and Bacillus sp. strain PeC11 are able to grow with glucose axenically by mixed acid fermentation yielding lactate, acetate, formate, succinate, and ethanol as fermentation products. Alternatively, the isolated strain grew anaerobically in pure culture if pyruvate was added to glucose-containing media, and lactate, acetate and formate were the major fermentation products, but the strain never produced ethanol. Aerobic growth was found with a variety of organic substrates in the presence of partly reduced sulfur compounds. In the absence of sulfide and oxygen, nitrate served as an electron acceptor. Strain BoGlc83 was characterized as the type strain of a new species for which the name Bacillus stamsii sp. nov. (DSM 19598=JCM 30025) is proposed.

  3. Freshwater Macroinvertebrates.

    ERIC Educational Resources Information Center

    Nalepa, T. F.

    1978-01-01

    Presents a literature review of freshwater biology particularly freshwater macroinvertebrates and their effect on water pollution, covering publications of 1976-77. A list of 158 references is also presented. (HM)

  4. Differential toxicity of Al2O3 particles on Gram-positive and Gram-negative sediment bacterial isolates from freshwater.

    PubMed

    Bhuvaneshwari, M; Bairoliya, Sakcham; Parashar, Abhinav; Chandrasekaran, N; Mukherjee, Amitava

    2016-06-01

    The current study was aimed to explore the differential effects on Gram-positive and Gram-negative freshwater sediment bacterial isolates upon exposure to nano-particles and bulk particles of Al2O3 at low concentrations (0.25, 0.5, and 1 mg/L). The Gram-negative Pseudomonas aeruginosa was more susceptible to both the nano-forms and bulk forms than the Gram-positive Bacillus altitudinis. The generation of reactive oxygen species (ROS) and release of lipopolysaccharide due to membrane damage were dependent on the dose of nano-Al2O3. The Fourier transform infrared spectroscopy (FT-IR) studies confirmed the attachment of nano-Al2O3 on bacterial cells, which may lead to subsequent changes in the cell membrane composition and integrity. Internalization of nano-Al2O3 was estimated to be more for P. aeruginosa than for B. altitudinis cells. As a role of defense mechanism, the biofilm formation and production of extracellular polymeric substances (EPSs; polysaccharide and protein) were increased with respect to the concentration of toxicant. Nano-Al2O3 was estimated to cause more DNA damage than the bulk particles in both Gram-positive and Gram-negative bacterial strains.

  5. Arsenic and heavy metal pollution in wetland soils from tidal freshwater and salt marshes before and after the flow-sediment regulation regime in the Yellow River Delta, China

    NASA Astrophysics Data System (ADS)

    Bai, Junhong; Xiao, Rong; Zhang, Kejiang; Gao, Haifeng

    2012-07-01

    SummarySoil samples were collected in tidal freshwater and salt marshes in the Yellow River Delta (YRD), northern China, before and after the flow-sediment regulation. Total concentrations of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) were determined using inductively coupled plasma atomic absorption spectrometry to investigate the characteristics of heavy metal pollution in tidal wetlands before and after the regulation regime. The results demonstrated that marsh soils in both marshes had higher silt and total P contents, higher bulk density and lower sand contents after the flow-sediment regulation; moreover, soil salinity was significantly decreased in the tidal salt marsh. As and Cd concentrations were significantly higher in both marsh soils after the regulation than before, and there were no significant differences in the concentrations of Cu, Pb and Zn measured before and after the regulation. No significant differences in heavy metal concentrations were observed between freshwater and salt marsh soils, either before or after the regulation. Before the regulation regime, soil organic matter, pH and sulfer (S) were the main factors influencing heavy metal distribution in tidal freshwater marshes, whereas for tidal salt marshes, the main factors are soil salinity and moisture, pH and S. However, bulk density and total P became the main influencing factors after the regulation. The sediment quality guidelines and geoaccumulation indices showed moderately or strongly polluted levels of As and Cd and unpolluted or moderately polluted levels of Cu, Pb and Zn; As and Cd pollution became more serious after the regulation. Factor analysis indicated thatthese heavy metals including As were closely correlated and orginated from common pollution sources before the flow-sediment regulation; however, the sources of As and Cd separated from the sources of Cu, Pb and Zn after the regulation regime, implying that the flow-sediment regulation regime

  6. Geochemical data as indicators of environmental change and human impact in sediments derived from downstream marshes of an ephemeral river, Northeast China

    NASA Astrophysics Data System (ADS)

    Wang, Guo-Ping; Zhai, Zheng-Li

    2008-01-01

    Recent sedimentary history of natural environmental change and anthropogenic influence in an ephemeral river catchment has been reconstructed using selected major and trace elements, element ratios, and their different geochemical phases ( Tessier sequential extraction methods), pollen, and grain size combined with 210Pb- and 137Cs-dating method in marsh sedimentary cores. Attempts were made to use selected element ratios with different geochemical phases—residual phase of Ti, Al, V, Cr, Ni, Rb, K, Sr, and Ba; mobile Sr and Ba—combined with 210Pb- and 137Cs-chronology to interpret certain time information of environmental changes saved within the marsh sediments. Results indicate that there were two marked humid periods during 1850-1860 ad and 1890-1920 ad, and sand storm activities prevailed during 1920-1930 ad. After about 1900 ad, soil erosion has increased with the extensive agricultural activities in the Huolin River catchments, and further intensified after 1950s. After 1980, soil erosion has become even more intense, which is consistent with the reinforcement of human activities, the drastic loss of vegetation cover in the upstream lands, especially, the exploitation of the open cast coalmine in the upstream of Huolin River at that time. Influenced by the inundation of the Huolin River, the heavy metal pollution historical trends in Xianghai marsh wetland could be roughly divided into three periods by analysis of sediment enrichment factor (KSEF) and the index of geoaccumulation ( I geo):1760-1880 ad, 1880-1980 ad, and 1980-now. Human activities accelerate the inputs of heavy metal, which leads to degradation of the marsh. This study also investigated on source of marsh sediments (by Ti/Al), redox condition [by V/Cr and V/(V + Ni)], and salinization indicators (by Sr/Ba and Rb/K). The results demonstrate that sources of sediments and redox conditions were partly similar for both riparian and depressional marshes. Besides, some differences in degree of

  7. The effect of freshwater inflow on meiofaunal consumption of sediment bacteria and microphytobenthos in San Antonio Bay, Texas, U.S.A.

    NASA Astrophysics Data System (ADS)

    Montagna, Paul A.; Yoon, Won Bae

    1991-12-01

    If meiofauna are food-limited then they should respond with increased feeding rates when microbial production is stimulated. River inflow into estuaries is a source of organic matter that can be limiting to bacterial production, and nutrients that might limit primary production. Therefore, inflow should stimulate microbial primary and secondary production, and eventually meiofauna grazing rates should increase as a functional response to increased food availability and quality. To determine if meiofauna grazing rates were affected by inflow, two replicate stations were sampled in the upper, river-dominated end, of San Antonio Bay and contrasted with two replicate stations at the lower end of the estuary. The experiments were performed three times. Water column nutrients and sediment organic matter were higher in the upper end of the estuary than in the lower end. Benthic primary production was 2·5 times higher in the upper end than in the lower end. Benthic metabolism (measured by oxygen consumption) was also higher in the upper end, but bacterial production (measured by thymidine uptake) was not significantly different between the two ends. Grazing rates were 3·5 times higher on bacteria, and 2·5 times higher on microalgae in the upper end of the estuary than in the lower end, confirming our hypothesis that inflow would stimulate grazing rates. Grazing rates were dominated by juvenile molluscs (temporary meiofauna) which accounted for 39% of the microalgae and 68% of the bacteria ingested by the community. Juvenile molluscs were most prevalent in the upper, fresh-water zone. Harpacticoid copepods and nematodes had higher grazing rates in the lower end of the estuary. Grazing rates were higher on microalgae than on bacteria: 4% of the microalgae were removed per hour, compared to only 1% of the bacteria. Grazing rates on microalgae were 2·6 times higher than productivity, indicating meiofauna might be food-limited. Grazing on bacteria was low, and production

  8. Davis Pond Freshwater Prediversion Biomonitoring Study: Freshwater Fisheries and Eagles

    USGS Publications Warehouse

    Jenkins, Jill A.; Bourgeois, E. Beth; Jeske, Clint W.

    2008-01-01

    In January 2001, the construction of the Davis Pond freshwater diversion structure was completed by the U.S. Army Corps of Engineers. The diversion of freshwater from the Mississippi River is intended to mitigate saltwater intrusion from the Gulf of Mexico and to lessen the concomitant loss of wetland areas. In addition to the freshwater inflow, Barataria Bay basin would receive nutrients, increased flows of sediments, and water-borne and sediment-bound compounds. The purpose of this biomonitoring study was, therefore, to serve as a baseline for prediversion concentrations of selected contaminants in bald eagle (Haliaeetus leucocephalus) nestlings (hereafter referred to as eaglets), representative freshwater fish, and bivalves. Samples were collected from January through June 2001. Two similarly designed postdiversion studies, as described in the biological monitoring program, are planned. Active bald eagle nests targeted for sampling eaglet blood (n = 6) were generally located southwest and south of the diversion structure. The designated sites for aquatic animal sampling were at Lake Salvador, at Lake Cataouatche, at Bayou Couba, and along the Mississippi River. Aquatic animals representative of eagle prey were collected. Fish were from three different trophic levels and have varying feeding strategies and life histories. These included herbivorous striped mullet (Mugil cephalus), omnivorous blue catfish (Ictalurus furcatus), and carnivorous largemouth bass (Micropterus salmoides). Three individuals per species were collected at each of the four sampling sites. Freshwater Atlantic rangia clams (Rangia cuneata) were collected at the downstream marsh sites, and zebra mussels (Dreissena spp.) were collected on the Mississippi River. The U.S. Geological Survey (USGS) Biomonitoring of Environmental Status and Trends (BEST) protocols served as guides for fish sampling and health assessments. Fish are useful for monitoring aquatic ecosystems because they accumulate

  9. Stripping voltammetric determination of palladium, platinum and rhodium in freshwater and sediment samples from South African water resources.

    PubMed

    van der Horst, C; Silwana, B; Iwuoha, E; Somerset, V

    2012-01-01

    reproducibility was also observed and the practical applicability of the sensor was demonstrated with the analysis of environmental water and sediment samples.

  10. Stripping voltammetric determination of palladium, platinum and rhodium in freshwater and sediment samples from South African water resources.

    PubMed

    van der Horst, C; Silwana, B; Iwuoha, E; Somerset, V

    2012-01-01

    reproducibility was also observed and the practical applicability of the sensor was demonstrated with the analysis of environmental water and sediment samples. PMID:22871006

  11. The effect of mining and related activities on the sediment-trace element geochemistry of Lake Coeur d'Alene, Idaho, USA. Part III. Downstream effects: The Spokane River Basin

    USGS Publications Warehouse

    Grosbois, C.A.; Horowitz, A.J.; Smith, J.J.; Elrick, K.A.

    2001-01-01

    During 1998/1999, surface and subsurface sediment samples were collected along the entire length of the Spokane River from its outlet at the northern end of Lake Coeur d'Alene (CDA), Idaho, to Lake Roosevelt on the Columbia River, Washington. The study was conducted to determine if the trace element enrichments observed in Lake CDA and on the floodplain and in the CDA River extend through the Spokane River Basin (SRB). As in Lake CDA, surface sediments in the SRB are enriched in Pb, Zn, As, Cd, Sb and Hg relative to local background levels. Pb, Cd and Zn are the most elevated, with maximum enrichment occurring in the upper Spokane River in close proximity to Lake CDA. On average, enrichment decreases downstream, apparently reflecting both increased distance from the inferred source (the CDA River Basin), as well as increased dilution by locally derived but unenriched materials. Only Cd and Zn display marked enrichment throughout the SRB. Pb, Zn and Cd seem to be associated mainly with an operationally defined iron oxide phase, whereas the majority of the As and Sb seem to be matrix-held. Subsurface sediments also are enriched in Pb, Zn, As, Cd, Sb and Hg relative to background levels. Based on 137Cs and excess 210Pb dating, trace element enrichment began in the middle part of the SRB (Long Lake) between 1900 and 1920. This is contemporaneous with similar enrichments observed in Lake CDA, as well as the completion of Long Lake Dam (1913). In the most downstream part of the basin (Spokane River Arm of Lake Roosevelt), enrichment began substantially later, between 1930 and 1940. The temporal difference in enrichment between Long Lake and the River Arm may reflect the latter's greater distance from the presumed source of the enrichment (the CDA River Basin); however, the difference is more likely the result of the completion of Grand Coulee Dam (1934-1941), which formed Lake Roosevelt, backed up the Spokane River, and increased water levels in the River Armby about 30

  12. Modeling flow and sediment transport dynamics in the lowermost Mississippi River, Louisiana, USA, with an upstream alluvial-bedrock transition and a downstream bedrock-alluvial transition: Implications for land building using engineered diversions

    NASA Astrophysics Data System (ADS)

    Viparelli, Enrica; Nittrouer, Jeffrey A.; Parker, Gary

    2015-03-01

    The lowermost Mississippi River, defined herein as the river segment downstream of the Old River Control Structure and hydrodynamically influenced by the Gulf of Mexico, extends for approximately 500 km. This segment includes a bedrock (or more precisely, mixed bedrock-alluvial) reach that is bounded by an upstream alluvial-bedrock transition and a downstream bedrock-alluvial transition. Here we present a one-dimensional mathematical formulation for the long-term evolution of lowland rivers that is able to reproduce the morphodynamics of both the alluvial-bedrock and the bedrock-alluvial transitions. Model results show that the magnitude of the alluvial equilibrium bed slope relative to the bedrock surface slope and the depth of bedrock surface relative to the water surface base level strongly influence the mobile bed equilibrium of low-sloping river channels. Using data from the lowermost Mississippi River, the model is zeroed and validated at field scale by comparing the numerical results with field measurements. The model is then applied to predict the influence on the stability of channel bed elevation in response to delta restoration projects. In particular, the response of the river bed to the implementation of two examples of land-building diversions to extract water and sediment from the main channel is studied. In this regard, our model results show that engineered land-building diversions along the lowermost Mississippi River are capable of producing equilibrated bed profiles with only modest shoaling or erosion, and therefore, such diversions are a sustainable strategy for mitigating land loss within the Mississippi River Delta.

  13. Biological assessment of proposed US Army Corps of Engineers navigation dredging and disposal on freshwater mussels at sites downstream from Cordell Hull Dam, Cumberland River miles 303. 8 to 309. 2

    SciTech Connect

    Jenkinson, J.J.; Hickman, G.D.

    1983-10-01

    Preimpoundment survey data indicate that at least four freshwater mussel species now listed as endangered by the US Fish and Wildlife Service (Dromus dromas, Lampsilis orbiculata, Plethobasus cooperianus and Pleurobema plenum) once occurred in or near CRM 303 to 309. Post impoundment surveys, including this study, indicate the L. orbiculata is widespread but uncommon throughout at least a 40 mile reach of the upper Cumberland River while the other three species persist only as rare old individuals. This survey of potential dredge, disposal and adjacent sites in CRM 305.8 to 309.1 indicated that the mussel fauna consisted of 22 species and was not particularly abundant. Lampsilis orbiculata was found to occur in proposed dredge sites at CRM 305.3, 306.5 and 307.0. The diversity and density of other species at CRM 305.5 suggested that L. orbiculata also may occur at that proposed dredge site. The single potential disposal site where L. orbiculata was found is located at CRM 305.1 to .5. Pleurobema plenum was found only at the proposed dredge site at CRM 307.0. Extensive habitat modification at any of the five dredge or disposal sites where endangered species were found or suspected, could be expected to eliminate resident specimens. Loss of L. orbiculata specimens at these sites would not constitute a substantial impact to the species throughout its range or in this reach of the Cumberland River. Loss of P. plenum at CRM 307.0 would eliminate a few of the surviving specimens of this species in the river. 10 references, 2 figures, 4 tables.

  14. Survival and persistence of host-associated Bacteroidales cells and DNA in comparison with Escherichia coli and Enterococcus in freshwater sediments as quantified by PMA-qPCR and qPCR.

    PubMed

    Kim, Minji; Wuertz, Stefan

    2015-12-15

    Decay of the fecal source identifier Bacteroidales in sediments has not been studied until now. Two types of microcosms inoculated with human, cow and dog feces were constructed to investigate the survival and persistence of host-associated Bacteroidales cells and their DNA, respectively, in freshwater sediments: (i) a completely anaerobic microcosm where feces were entirely mixed with sediments for estimating decay of Bacteroidales in oxygen-free sediments at two temperatures (6 °C and 20 °C) and (ii) a core microcosm where feces in the overlying water column settled on top of undisturbed core sediments. Quantitative PCR (qPCR) along with propidium monoazide (PMA) was used to differentiate between genetic markers present in intact cells and total intracellular as well as extracellular marker DNA. Regulated fecal indicator bacteria were measured by cultivation (Escherichia coli and Enterococcus) and qPCR (Enterococcus) in relation to Bacteroidales-associated host markers. In anaerobic microcosms, the survival and persistence of Bacteroidales cells and DNA in sediments were considerably extended, especially at the lower temperature of 6 °C, with two-log reduction times (T99) >56 d (cells) and >169 d (DNA). Bacteroidales DNA persisted up to five times longer than cells in anaerobic microcosms at 6 °C, whereas decay rates of cells and DNA were not significantly different at 20 °C in anaerobic microcosms. In core microcosms, the levels of Bacteroidales cells and DNA decreased approximately six times more slowly in sediments than in overlying water; T99 values of Bacteroidales cells and DNA were 6-9 d (water) and 29-82 d (sediment). The survival of universal, human-, ruminant- and dog-associated Bacteroidales cells in sediments was similar in both microcosms under each given condition, as was the persistence of DNA. Decay rate constants of Bacteroidales cells and DNA were comparable with those of cultivable Enterococcus and E. coli cells in core sediments while

  15. Assessing the impacts of Three Gorges Dam on lake inundation areas across the downstream Yangtze floodplain

    NASA Astrophysics Data System (ADS)

    Wang, J.; Sheng, Y.; Wada, Y.

    2013-12-01

    China's Three Gorges Dam (TGD) has received worldwide attention due to its profound impacts on the downstream hydraulic, morphological, and ecological systems. The TGD operation results in direct alternation of the discharge to the middle and lower Yangtze reach, manifested as regulated flow and reduced sediment load. TGD's flow regulation, typically described as water storage in fall while release in winter and spring, interferes with the natural seasonality of downstream Yangtze River levels which are essentially important to the inundation dynamics of surrounding lakes/wetlands in the Yangtze floodplain. Concurrent decrease of sediment load has caused chronic downstream channel erosion which lowers Yangtze level in relation to flow and further affects the sustainability of riparian lakes and the related ecosystems. By integrating satellite observations, in situ measurement, and hydrologic simulations, this study presents a systematic assessment of the TGD impacts on the inundation areas of six major freshwater lakes across the entire Yangtze basin downstream of the TGD, during the time period from TGD's initial impoundment in June 2003 to early 2012. Despite the small number, the six targeted lakes cover a total area of ~5,000 km2 accounting for ~25% of the freshwater lake area in China, and were identified as the only natural lakes that remain in open connection to the Yangtze River across the downstream floodplain. Using daily MODIS imagery from 2000 to 2012, we revealed a significant year-round decline in the aggregated inundation area of the studied lakes by an average of ~580 km2 or 17.7% from the pre-dam to post-dam period (i.e., before and after June, 2003). To diagnose TGD's contribution to such lake area decline, we followed a two-step procedure by first quantifying the TGD impacts on the seasonal level regime along the complete longitudinal range of the Yangtze River downstream from TGD to the estuary [Wang et al., 2013], and then estimating the

  16. Use of Sediment Budgets for Watershed Erosion Control Planning: A Case Study From Northern California

    NASA Astrophysics Data System (ADS)

    O'Connor, M.; McDavitt, W.

    2002-05-01

    Erosion, sedimentation and peak flow increases caused by forest management for commercial timber production may negatively affect aquatic habitat of endangered anadromous fish such as coho salmon ({\\ it O. kisutch}). This paper summarizes a portion of a Watershed Analysis study performed for Pacific Lumber Company, Scotia, CA, focusing on erosion and sedimentation processes and rates and downstream sediment routing and water quality in the Freshwater Creek watershed in northwest California. Hillslope, road and bank erosion, channel sedimentation and sediment rates were quantified using field surveys, aerial photo interpretation, and empirical modeling approaches for different elements of the study. Sediment transport rates for bedload were modeled, and sediment transport rates for suspended sediment were estimated based on size distribution of sediment inputs in relation to sizes transported in suspension. The resulting sediment budget was validated through comparison using recent short-term, high-quality estimates of suspended sediment yield collected by a community watershed group at a downstream monitoring site with technical assistance from the US Forest Service. Another check on the sediment budget was provided by bedload yield data from an adjacent watershed, Jacoby Creek. The sediment budget techniques and bedload routing models used for this study provide sediment yield estimates that are in good agreement with available data. These results suggest that sediment budget techniques that require moderate levels of fieldwork can be used to provide relatively accurate technical assessments for use in the TMDL process. The sediment budget also identifies the most significant sediment sources and suggests a framework within which effective erosion control strategies can be developed.

  17. Microplastics in freshwater systems: a review of the emerging threats, identification of knowledge gaps and prioritisation of research needs.

    PubMed

    Eerkes-Medrano, Dafne; Thompson, Richard C; Aldridge, David C

    2015-05-15

    Plastic contamination is an increasing environmental problem in marine systems where it has spread globally to even the most remote habitats. Plastic pieces in smaller size scales, microplastics (particles <5 mm), have reached high densities (e.g., 100,000 items per m(3)) in waters and sediments, and are interacting with organisms and the environment in a variety of ways. Early investigations of freshwater systems suggest microplastic presence and interactions are equally as far reaching as are being observed in marine systems. Microplastics are being detected in freshwaters of Europe, North America, and Asia, and the first organismal studies are finding that freshwater fauna across a range of feeding guilds ingest microplastics. Drawing from the marine literature and these initial freshwater studies, we review the issue of microplastics in freshwater systems to summarise current understanding, identify knowledge gaps and suggest future research priorities. Evidence suggests that freshwater systems may share similarities to marine systems in the types of forces that transport microplastics (e.g. surface currents); the prevalence of microplastics (e.g. numerically abundant and ubiquitous); the approaches used for detection, identification and quantification (e.g. density separation, filtration, sieving and infrared spectroscopy); and the potential impacts (e.g. physical damage to organisms that ingest them, chemical transfer of toxicants). Differences between freshwater and marine systems include the closer proximity to point sources in freshwaters, the typically smaller sizes of freshwater systems, and spatial and temporal differences in the mixing/transport of particles by physical forces. These differences between marine and freshwater systems may lead to differences in the type of microplastics present. For example, rivers may show a predictable pattern in microplastic characteristics (size, shape, relative abundance) based on waste sources (e.g. household vs

  18. Microplastics in freshwater systems: a review of the emerging threats, identification of knowledge gaps and prioritisation of research needs.

    PubMed

    Eerkes-Medrano, Dafne; Thompson, Richard C; Aldridge, David C

    2015-05-15

    Plastic contamination is an increasing environmental problem in marine systems where it has spread globally to even the most remote habitats. Plastic pieces in smaller size scales, microplastics (particles <5 mm), have reached high densities (e.g., 100,000 items per m(3)) in waters and sediments, and are interacting with organisms and the environment in a variety of ways. Early investigations of freshwater systems suggest microplastic presence and interactions are equally as far reaching as are being observed in marine systems. Microplastics are being detected in freshwaters of Europe, North America, and Asia, and the first organismal studies are finding that freshwater fauna across a range of feeding guilds ingest microplastics. Drawing from the marine literature and these initial freshwater studies, we review the issue of microplastics in freshwater systems to summarise current understanding, identify knowledge gaps and suggest future research priorities. Evidence suggests that freshwater systems may share similarities to marine systems in the types of forces that transport microplastics (e.g. surface currents); the prevalence of microplastics (e.g. numerically abundant and ubiquitous); the approaches used for detection, identification and quantification (e.g. density separation, filtration, sieving and infrared spectroscopy); and the potential impacts (e.g. physical damage to organisms that ingest them, chemical transfer of toxicants). Differences between freshwater and marine systems include the closer proximity to point sources in freshwaters, the typically smaller sizes of freshwater systems, and spatial and temporal differences in the mixing/transport of particles by physical forces. These differences between marine and freshwater systems may lead to differences in the type of microplastics present. For example, rivers may show a predictable pattern in microplastic characteristics (size, shape, relative abundance) based on waste sources (e.g. household vs

  19. Reservoir impacts downstream in highly regulated river basins: the Ebro delta and the Guadalquivir estuary in Spain

    NASA Astrophysics Data System (ADS)

    Polo, María J.; Rovira, Albert; García-Contreras, Darío; Contreras, Eva; Millares, Agustín; Aguilar, Cristina; Losada, Miguel A.

    2016-05-01

    Regulation by reservoirs affects both the freshwater regime and the sediment delivery at the area downstream, and may have a significant impact on water quality in the final transitional water bodies. Spain is one the countries with more water storage capacity by reservoirs in the world. Dense reservoir networks can be found in most of the hydrographic basins, especially in the central and southern regions. The spatial redistribution of the seasonal and annual water storage in reservoirs for irrigation and urban supply, mainly, has resulted in significant changes of water flow and sediment load regimes, together with a fostered development of soil and water uses, with environmental impacts downstream and higher vulnerability of these areas to the sea level rise and drought occurrence. This work shows these effects in the Guadalquivir and the Ebro River basins, two of the largest regulated areas in Spain. The results show a 71 % decrease of the annual freshwater input to the Guadalquivir River estuary during 1930-2014, an increase of 420 % of the irrigated area upstream the estuary, and suspended sediment loads up to 1000 % the initial levels. In the Ebro River delta, the annual water yield has decreased over a 30 % but, on the contrary, the big reservoirs are located in the main stream, and the sediment load has decreased a 99 %, resulting in a delta coastal regression up to 10 m per year and the massive presence of macrophytes in the lower river. Adaptive actions proposed to face these impacts in a sea level rise scenario are also analyzed.

  20. Freshwater Wetlands.

    ERIC Educational Resources Information Center

    Naturescope, 1986

    1986-01-01

    Provides descriptions about freshwater wetlands, such as marshes, swamps, and bogs. Contains three learning activities which deal with unusual wetland plants, the animals and plants in a typical marsh, and the effects of a draught on a swamp. Included are reproducible handouts and worksheets for two of the activities. (TW)

  1. In-situ Subaqueous Capping of Mercury-Contaminated Sediments in a Fresh-Water Aquatic System, Part I-Bench-Scale Microcosm Study to Assess Methylmercury Production

    EPA Science Inventory

    Bench-scale microcosm experiments were designed to provide a better understanding of the potential for Hg methylation in sediments from an aquatic environment. Experiments were conducted to examine the function of sulfate concentration, lactate concentration, the presence/absenc...

  2. Mapping localised freshwater anomalies in the brackish paleo-lake sediments of the Machile-Zambezi Basin with transient electromagnetic sounding, geoelectrical imaging and induced polarisation

    NASA Astrophysics Data System (ADS)

    Chongo, Mkhuzo; Christiansen, Anders Vest; Fiandaca, Gianluca; Nyambe, Imasiku A.; Larsen, Flemming; Bauer-Gottwein, Peter

    2015-12-01

    A recent airborne TEM survey in the Machile-Zambezi Basin of south western Zambia revealed high electrical resistivity anomalies (around 100 Ωm) in a low electrical resistivity (below 13 Ωm) background. The near surface (0-40 m depth range) electrical resistivity distribution of these anomalies appeared to be coincident with superficial features related to surface water such as alluvial fans and flood plains. This paper describes the application of transient electromagnetic soundings (TEM) and continuous vertical electrical sounding (CVES) using geo-electrics and time domain induced polarisation to evaluate a freshwater lens across a flood plain on the northern bank of the Zambezi River at Kasaya in south western Zambia. Coincident TEM and CVES measurements were conducted across the Simalaha Plain from the edge of the Zambezi River up to 6.6 km inland. The resulting TEM, direct current and induced polarisation data sets were inverted using a new mutually and laterally constrained joint inversion scheme. The resulting inverse model sections depict a freshwater lens sitting on top of a regional saline aquifer. The fresh water lens is about 60 m thick at the boundary with the Zambezi River and gradually thins out and deteriorates in water quality further inland. It is postulated that the freshwater lens originated as a result of interaction between the Zambezi River and the salty aquifer in a setting in which evapotranspiration is the net climatic stress. Similar high electrical resistivity bodies were also associated with other surface water features located in the airborne surveyed area.

  3. Genotoxic and teratogenic effect of freshwater sediment samples from the Rhine and Elbe River (Germany) in zebrafish embryo using a multi-endpoint testing strategy.

    PubMed

    Garcia-Käufer, M; Gartiser, S; Hafner, C; Schiwy, S; Keiter, S; Gründemann, C; Hollert, H

    2015-11-01

    The embryotoxic potential of three model sediment samples with a distinct and well-characterized pollutant burden from the main German river basins Rhine and Elbe was investigated. The Fish Embryo Contact Test (FECT) in zebrafish (Danio rerio) was applied and submitted to further development to allow for a comprehensive risk assessment of such complex environmental samples. As particulate pollutants are constructive constituents of sediments, they underlay episodic source-sink dynamics, becoming available to benthic organisms. As bioavailability of xenobiotics is a crucial factor for ecotoxicological hazard, we focused on the direct particle-exposure pathway, evaluating throughput-capable endpoints and considering toxicokinetics. Fish embryo and larvae were exposed toward reconstituted (freeze-dried) sediment samples on a microcosm-scale experimental approach. A range of different developmental embryonic stages were considered to gain knowledge of potential correlations with metabolic competence during the early embryogenesis. Morphological, physiological, and molecular endpoints were investigated to elucidate induced adverse effects, placing particular emphasis on genomic instability, assessed by the in vivo comet assay. Flow cytometry was used to investigate the extent of induced cell death, since cytotoxicity can lead to confounding effects. The implementation of relative toxicity indices further provides inter-comparability between samples and related studies. All of the investigated sediments represent a significant ecotoxicological hazard by disrupting embryogenesis in zebrafish. Beside the induction of acute toxicity, morphological and physiological embryotoxic effects could be identified in a concentration-response manner. Increased DNA strand break frequency was detected after sediment contact in characteristic non-monotonic dose-response behavior due to overlapping cytotoxic effects. The embryonic zebrafish toxicity model along with the in vivo comet

  4. Sediment retention in a bottomland hardwood wetland in Eastern Arkansas

    USGS Publications Warehouse

    Kleiss, B.A.

    1996-01-01

    One of the often-stated functions of wetlands is their ability to remove sediments and other particulates from water, thus improving water quality in the adjacent aquatic system. However, actual rates of suspended sediment removal have rarely been measured in freshwater wetland systems. To address this issue, suspended sediment dynamics were measured in a 85-km2 bottomland hardwood (BLH) wetland adjacent to the highly turbid Cache River in eastern Arkansas during the 1988-1990 water years. A suspended sediment mass balance was calculated using depth-integrated, flow-weighted daily measurements at wetland inflow and outflow points. Over the three-year period, suspended sediment load decreased an average of 14% between upstream and downstream sampling points. To test the idea that the suspended sediments were retained by the adjacent wetland and to determine what portion of the BLH forest was most responsible for retaining the suspended sediments, concurrent measurements of sediment accretion were made at 30 sites in the wetland using feldspar clay marker horizons, sedimentation disks, the 137cesium method, and dendrogeomorphic techniques. Sedimentation rates exceeding 1 cm/yr were measured in frequently flooded areas dominated by Nyssa aquatica and Taxodium distichum. Maximum sedimentation rates did not occur on the natural levee, as would be predicted by classical fluvial geomorphology, but in the "first bottom," where retention time of the water reached a maximum. Multiple regression was used to relate sedimentation rates with several physical and biological factors. A combination of distance from the river, flood duration, and tree basal area accounted for nearly 90% of the variation in sedimentation rates.

  5. Field-based and laboratory stable isotope probing surveys of the identities of both aerobic and anaerobic benzene-metabolizing microorganisms in freshwater sediment.

    PubMed

    Liou, J S-C; Derito, C M; Madsen, E L

    2008-08-01

    Laboratory incubations of coal-tar waste-contaminated sediment microbial communities under relatively controlled physiological conditions were used to interpret results of a field-based stable isotope probing (SIP) assay. Biodegradation activity of 13C-benzene was examined by GC/MS determination of net 13CO2 production and by GC headspace analysis of benzene loss. Key experimental variables were: the site of the assays (laboratory serum-bottle incubations and in situ field sediments), benzene concentration (10, 36 or 200 p.p.m. in laboratory assays), and physiological conditions (anaerobic with or without sulfate or nitrate additions versus aerobic headspace or the uncontrolled field). In anaerobic laboratory incubations of benzene at 10 p.p.m., greater than 60% of the substrate was eliminated within 15 days. During anaerobic incubations of 200 p.p.m. benzene (70 days), 0.9% benzene mineralization occurred. When benzene (36 p.p.m.) was added to sediment with air in the serum-bottle headspace, 14% of the initial 13C was mineralized to 13CO2 in 2.5 days. In the field experiment (178 microg 13C-benzene dosed to undisturbed sediments), net 13CO2 production reached 0.3% within 8.5 h. After isopycnic separation of 13C (heavy)-labelled DNA from the above biodegradation assays, sequencing of 13C-DNA clone libraries revealed a broad diversity of taxa involved in benzene metabolism and distinctive libraries for each biodegradation treatment. Perhaps most importantly, in the field SIP experiment the clone libraries produced were dominated by Pelomonas (betaproteobacteria) sequences similar to those found in the anaerobic 10 p.p.m. benzene laboratory experiment. These data indicate that the physiological conditions that prevail and govern in situ biodegradation of pollutants in the field may be interpreted by knowing the physiological preferences of potentially active populations.

  6. Distribution of heavy metals in vegetation surrounding the Blackstone River, USA: considerations regarding sediment contamination and long term metals transport in freshwater riverine ecosystems.

    PubMed

    Ozdilek, Hasan Goksel; Mathisen, Paul P; Pellegrino, Don

    2007-04-01

    The Blackstone River, a 74 km interstate stream located in South Central Massachusetts and Rhode Island (USA), has had a long history of problems due to high concentrations of metals such as copper and lead. The river has been subjected to metals load that include contributions from urban runoff, wastewater discharges, contaminated sediments, and also resuspension of contaminated sediments in the river-bed. All of these effects lead to elevated concentrations of metals such as lead, copper, zinc, chromium, cadmium and arsenic. Furthermore, the contaminated sediments located behind impoundments become especially important when higher flows cause resuspension of the previously deposited sediments and associated metals. While it is known that high metals concentrations in this river are found in the bottom sediments, the fate of the metals and impact on the ecosystem are not well known. This paper addresses the potential impacts that metals may have on vegetation and plant tissues in the vicinity of the river Plant tissues (primarily mosses), were collected from a number of sampling sites along a 14 km stretch of this river. At each site, samples were collected from multiple distances from the riverbank. Laboratory analyses made use of both wet digestion and dry ashing digestion methods, followed by analysis using an atomic absorption spectrophotometer. The wet and dry ashing digestion methods yielded similar results, although the results afforded by the dry ashing methods were slightly lower than the results obtained from the wet method. The results showed that the metals concentrations in vegetation (as determined from plant tissue analyses) were generally inversely related to the distance between the vegetation and the riverbank, with higher metals concentrations existing in plant tissues located close to the riverbank. In addition, it was found that the transport of metals concentrations to the terrestrial vegetation adjacent to this section of the Blackstone

  7. In-situ subaqueous capping of mercury-contaminated sediments in a fresh-water aquatic system, Part I—Bench-scale microcosm study to assess methylmercury production

    SciTech Connect

    Randall, Paul M.; Fimmen, Ryan; Lal, Vivek; Darlington, Ramona

    2013-08-15

    Bench-scale microcosm experiments were designed to provide a better understanding of the potential for Hg methylation in sediments from an aquatic environment. Experiments were conducted to examine the function of sulfate concentration, lactate concentration, the presence/absence of an aqueous inorganic Hg spike, and the presence/absence of inoculums of Desulfovibrio desulfuricans, a strain of sulfate-reducing bacteria (SRB) commonly found in the natural sediments of aquatic environments. Incubations were analyzed for both the rate and extent of (methylmercury) MeHg production. Methylation rates were estimated by analyzing MeHg and Hg after 2, 7, 14, 28, and 42 days. The production of metabolic byproducts, including dissolved gases as a proxy for metabolic utilization of carbon substrate, was also monitored. In all treatments amended with lactate, sulfate, Hg, and SRB, MeHg was produced (37 ng/g-sediment dry weight) after only 48 h of incubation and reached a maximum sediment concentration of 127 ng/g-sediment dry weight after the 42 day incubation period. Aqueous phase production of MeHg was observed to be 10 ng/L after 2 day, reaching a maximum observed concentration of 32.8 ng/L after 14 days, and declining to 10.8 ng/L at the end of the incubation period (42 day). The results of this study further demonstrates that, in the presence of an organic carbon substrate, sulfate, and the appropriate consortia of microorganisms, sedimentary Hg will be transformed into MeHg through bacterial metabolism. Further, this study provided the basis for evaluation of an in-situ subaqueous capping strategy that may limit (or potentially enhance) MeHg production. -- Highlights: • Hg methylation by SRB is limited by the depletion of sulfate and carbon. • Hg methylation is sensitive to competition by methanogens for carbon substrate. • In high lactate environment, all lactate was utilized in the microcosms within seven days. • In the absence of adequate metabolic fuel, Me

  8. Freshwater Flow Charts - 1995

    SciTech Connect

    Kaiper, G V

    2003-11-21

    This report covers the following: (1) Explanation of Charts Showing Freshwater Flow in 1995; (2) Estimated U.S. Freshwater Flow in 1995 (chart); (3) Estimated California Freshwater Flow in 1995 (chart); (4) Estimated New Mexico Freshwater Flow in 1995 (chart); and (5) Web locations and credits.

  9. Thailand's downstream projects proliferate

    SciTech Connect

    Not Available

    1991-06-03

    Thailand continues to press expansion and modernization of its downstream sector. Among recent developments: Construction of an olefins unit at Thailand's second major petrochemical complex and a worldscale aromatics unit in Thailand is threatened by rising costs. Thailand's National Petrochemical Corp (NPC) let a 9 billion yen contract to Mitsui Engineering and Shipbuilding Co. and C. Itoh and Co. for a dual fuel cogeneration power plant at its Mab Ta Phud, Rayong province, petrochemical complex. Financing is in place to flash a green light for a $530 million Belgian-Thai joint venture sponsoring a worldscale polyvinyl chloride/vinyl chloride monomer plant in Thailand. Work is more than 50% complete on the $345 million second phase expansion of Thai Oil's Sri Racha refinery in Chon Buri province. Petroleum Authority of Thailand (PTT) endorsed a plan to install two more natural gas processing plants in Thailand to meet rapidly growing domestic demand for petroleum gas.

  10. Relevance of the bioavailable fraction of DDT and its metabolites in freshwater sediment toxicity: New insight into the mode of action of these chemicals on Dictyostelium discoideum.

    PubMed

    Sforzini, Susanna; Governa, Daniela; Boeri, Marta; Oliveri, Laura; Oldani, Alessandro; Vago, Fabio; Viarengo, Aldo; Borrelli, Raffaella

    2016-10-01

    In this work, the toxicity of lake sediments contaminated with DDT and its metabolites DDD and DDE (collectively, DDX) was evaluated with widely used toxicity tests (i.e., Vibrio fischeri, Daphnia magna, Pseudokirchneriella subcapitata, and Lumbriculus variegatus) and with the social amoeba Dictyostelium discoideum, a model organism that is also suitable for studying pollutant-induced alterations at the molecular and cellular levels. Although the DDX concentration in the sediments was high (732.5 ppb), the results suggested a minimal environmental risk; in fact, no evidence of harmful effects was found using the different bioassays or when we considered the results of more sensitive sublethal biomarkers in D. discoideum amoebae. In line with the biological results, the chemical data showed that the concentration of DDX in the pore water (in general a highly bioavailable phase) showed a minimal value (0.0071ppb). To confirm the importance of the bioavailability of the toxic chemicals in determining their biological effects and to investigate the mechanisms of DDX toxicity, we exposed D. discoideum amoebae to 732.5ppb DDX in water solution. DDX had no effect on cell viability; however, a strong reduction in amoebae replication rate was observed, which depended mainly on a reduction in endocytosis rate and on lysosomal and mitochondrial alterations. In the presence of a moderate and transient increase in reactive oxygen species, the glutathione level in DDX-exposed amoebae drastically decreased. These results highlight that studies of the bioavailability of pollutants in environmental matrices and their biological effects are essential for site-specific ecological risk assessment. Moreover, glutathione depletion in DDX-exposed organisms is a new finding that could open the possibility of developing new pesticide mixtures that are more effective against DDT-resistant malaria vectors. PMID:27340883

  11. Uptake of Cadmium, Copper, Lead, and Zinc from Sediments by an Aquatic Macrophyte and by Terrestrial Arthropods in a Freshwater Wetland Ecosystem.

    PubMed

    Kim, Heung-Tae; Kim, Jae Geun

    2016-08-01

    The objective of this study was to investigate trace-metal [cadmium (Cd), copper (Cu), lead (Pb), zinc (Zn)] biotransference and biomagnification in terrestrial biota at different trophic levels (primary producer-top predator) of a wetland ecosystem. We investigated whether metal concentrations in the sediment are reflected in terrestrial arthropods and aquatic plants. We sampled the floating-leaved plant Trapa japonica; its species-specific primary consumer, the leaf beetle Galerucella nipponensis; and two predatory arthropods (the water strider Gerris sp. and the wolf spider Arctosa sp.) from three wetlands with different sedimentary metal concentrations. The δ(13)C and δ(15)N signatures in the trophic link between the plants and the leaf beetles supported the specificity of their feeding relationship. The stable isotope signatures indicate that the leaf beetle could be an important link in the trophic transfer of the metals. Transference factors (TFs) were <1 for Pb in all trophic links, and concentrations in the organisms were negatively correlated with the trophic levels. There was no evidence of Pb biomagnification in the food chain. Cu and Zn had TF >1 for all biota, and the concentrations were positively correlated with the trophic levels. Thus, there may be Cu and Zn biomagnification in the arthropods. We noted TF <1 for Cd between the plants and the leaf beetles, but TF was >1 among the arthropods. Therefore, Cd is probably not biomagnified between T. japonica and G. nipponensis, but it might be biomagnified in the arthropods. The metal burden in terrestrial arthropods may also be influenced by uptake from the sediment by aquatic plants.

  12. Uptake of Cadmium, Copper, Lead, and Zinc from Sediments by an Aquatic Macrophyte and by Terrestrial Arthropods in a Freshwater Wetland Ecosystem.

    PubMed

    Kim, Heung-Tae; Kim, Jae Geun

    2016-08-01

    The objective of this study was to investigate trace-metal [cadmium (Cd), copper (Cu), lead (Pb), zinc (Zn)] biotransference and biomagnification in terrestrial biota at different trophic levels (primary producer-top predator) of a wetland ecosystem. We investigated whether metal concentrations in the sediment are reflected in terrestrial arthropods and aquatic plants. We sampled the floating-leaved plant Trapa japonica; its species-specific primary consumer, the leaf beetle Galerucella nipponensis; and two predatory arthropods (the water strider Gerris sp. and the wolf spider Arctosa sp.) from three wetlands with different sedimentary metal concentrations. The δ(13)C and δ(15)N signatures in the trophic link between the plants and the leaf beetles supported the specificity of their feeding relationship. The stable isotope signatures indicate that the leaf beetle could be an important link in the trophic transfer of the metals. Transference factors (TFs) were <1 for Pb in all trophic links, and concentrations in the organisms were negatively correlated with the trophic levels. There was no evidence of Pb biomagnification in the food chain. Cu and Zn had TF >1 for all biota, and the concentrations were positively correlated with the trophic levels. Thus, there may be Cu and Zn biomagnification in the arthropods. We noted TF <1 for Cd between the plants and the leaf beetles, but TF was >1 among the arthropods. Therefore, Cd is probably not biomagnified between T. japonica and G. nipponensis, but it might be biomagnified in the arthropods. The metal burden in terrestrial arthropods may also be influenced by uptake from the sediment by aquatic plants. PMID:27306449

  13. Methylation of Hg downstream from the Bonanza Hg mine, Oregon

    USGS Publications Warehouse

    Gray, John E.; Hines, Mark E.; Krabbenhoft, David P.; Thoms, Bryn

    2012-01-01

    Speciation of Hg and conversion to methyl-Hg were evaluated in stream sediment, stream water, and aquatic snails collected downstream from the Bonanza Hg mine, Oregon. Total production from the Bonanza mine was >1360t of Hg, during mining from the late 1800s to 1960, ranking it as an intermediate sized Hg mine on an international scale. The primary objective of this study was to evaluate the distribution, transport, and methylation of Hg downstream from a Hg mine in a coastal temperate climatic zone. Data shown here for methyl-Hg, a neurotoxin hazardous to humans, are the first reported for sediment and water from this area. Stream sediment collected from Foster Creek flowing downstream from the Bonanza mine contained elevated Hg concentrations that ranged from 590 to 71,000ng/g, all of which (except the most distal sample) exceeded the probable effect concentration (PEC) of 1060ng/g, the Hg concentration above which harmful effects are likely to be observed in sediment-dwelling organisms. Concentrations of methyl-Hg in stream sediment collected from Foster Creek varied from 11 to 62ng/g and were highly elevated compared to regional baseline concentrations (0.11-0.82ng/g) established in this study. Methyl-Hg concentrations in stream sediment collected in this study showed a significant correlation with total organic C (TOC, R2=0.62), generally indicating increased methyl-Hg formation with increasing TOC in sediment. Isotopic-tracer methods indicated that several samples of Foster Creek sediment exhibited high rates of Hg-methylation. Concentrations of Hg in water collected downstream from the mine varied from 17 to 270ng/L and were also elevated compared to baselines, but all were below the 770ng/L Hg standard recommended by the USEPA to protect against chronic effects to aquatic wildlife. Concentrations of methyl-Hg in the water collected from Foster Creek ranged from 0.17 to 1.8ng/L, which were elevated compared to regional baseline sites upstream and downstream

  14. Downstream in Mawrth Valles

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    The THEMIS VIS camera is capable of capturing color images of the Martian surface using five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from using multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.

    This false color image is from further downstream in Mawrth Valles than yesterday's image. The channel here is at the end of the vallis. This image was collected during the Northern Spring season.

    Image information: VIS instrument. Latitude 26.7, Longitude 340.2 East (19.8 West). 37 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages

  15. Evidence for the migration of steroidal estrogens through river bed sediments.

    PubMed

    Labadie, Pierre; Cundy, Andrew B; Stone, Kevin; Andrews, Michael; Valbonesi, Sam; Hill, Elizabeth M

    2007-06-15

    Estrogenic substances discharged from wastewater treatment plants have been detected in surface sediments of receiving waters, but little is known of their vertical migration through buried sediments and their potential to contaminate subsurface waters. The vertical profiles of estrogenic chemicals were investigated in sediment cores at an alluvial freshwater site (Ditchling) and a clay-rich estuarine site (Lewes), both of which are downstream of wastewater discharges into the River Ouse (Sussex, U.K.). Estrone (E1) was the predominant estrogen detected in surface and buried sediments at both sites and was detected in undisturbed clay sediments > 120 years old. Profiles of E1 at Ditchling were characterized by a prominent subsurface peak of E1 at the alluvium/clay interface (-15 cm) at a concentration (28.8 +/- 6.0 ng/g of dry wt) that was 9-fold higher than in the surface sediment. In contrast, a steady downcore decline in E1 concentrations was observed in the clay-rich Lewes core. This work provides the first in situ evidence of estrogen migration through river bed sediments and reveals that movement of estrogens through unconsolidated sediment can result in penetration to the underlying substrata and therefore the potential for groundwater contamination.

  16. 5. AERATOR VIEW FROM DOWNSTREAM. FLUSH VALVE AT RIGHT OPENS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. AERATOR VIEW FROM DOWNSTREAM. FLUSH VALVE AT RIGHT OPENS TO CLEAR THE SYSTEM ABOVE THE SILT AND DEBRIS AND TO STOP THE FLOW OF WATER INTO THE SYSTEM DOWN LINE. BOX FLUME CONTINUES DOWN LINE TO SEDIMENTATION CHAMBER. - Kalaupapa Water Supply System, Waikolu Valley to Kalaupapa Settlement, Island of Molokai, Kalaupapa, Kalawao County, HI

  17. Effects of Pollution on Freshwater Organisms.

    PubMed

    Choudri, B S; Baawain, Mahad

    2016-10-01

    This review includes works published in the general scientific literature during 2015 on the effects of anthropogenic pollutants on freshwater organisms. It begins with two broad sections: research reviews and broad field studies and surveys. This is followed by reviews of research categorized in sections to reflect the pollutant class. These sections include wastewater, stormwater and non-point source pollution, nutrients, sediment cap materials and suspended clays, botanical extracts, surfactants, metals, persistent organic pollutants, pharmaceuticals, endocrine disruptors, pesticides, petroleum hydrocarbons and polycyclic aromatic hydrocarbons (PAHs), ionic liquids, and nanomaterials. The final section includes works describing innovations in the field of freshwater pollution research. PMID:27620107

  18. What makes a healthy environment for native freshwater mussels?

    USGS Publications Warehouse

    ,

    2000-01-01

    Freshwater mussels are sensitive to contamination of sediment that they inhabit and to the water that they filter, making the presence of live, adult mussels an excellent indicator of ecosystem health and stability. Freshwater mussels are relatively immobile, imbedded in the streambed with part of the shell sticking up into the water so that they can filter water to obtain oxygen and food. This lack of mobility makes them particularly vulnerable to water and sediment contamination, changes in sedimentation, or prolonged drought. Thus, ecosystem health and stability are critical for their reproduction and survival.

  19. Simultaneous measurements of tidal straining and advection at two parallel transects far downstream in the Rhine ROFI

    NASA Astrophysics Data System (ADS)

    Rijnsburger, Sabine; van der Hout, Carola M.; van Tongeren, Onno; de Boer, Gerben J.; van Prooijen, Bram C.; Borst, Wil G.; Pietrzak, Julie D.

    2016-05-01

    This study identifies and unravels the processes that lead to stratification and destratification in the far field of a Region of Freshwater Influence (ROFI). We present measurements that are novel for two reasons: (1) measurements were carried out with two vessels that sailed simultaneously over two cross-shore transects; (2) the measurements were carried out in the far field of the Rhine ROFI, 80 km downstream from the river mouth. This unique four dimensional dataset allows the application of the 3D potential energy anomaly equation for one of the first times on field data. With this equation, the relative importance of the depth mean advection, straining and nonlinear processes over one tidal cycle is assessed. The data shows that the Rhine ROFI extends 80 km downstream and periodic stratification is observed. The analysis not only shows the important role of cross-shore tidal straining but also the significance of along-shore straining and depth mean advection. In addition, the nonlinear terms seem to be small. The presence of all the terms influences the timing of maximum stratification. The analysis also shows that the importance of each term varies in the cross-shore direction. One of the most interesting findings is that the data are not inline with several hypotheses on the functioning of straining and advection in ROFIs. This highlights the dynamic behaviour of the Rhine ROFI, which is valuable for understanding the distribution of fine sediments, contaminants and the protection of coasts.

  20. Ecogeomorphological feedbacks in a tidal freshwater marsh

    NASA Astrophysics Data System (ADS)

    Palinkas, C. M.; Engelhardt, K.

    2013-12-01

    Tidal freshwater marshes are critical components of fluvial and estuarine ecosystems. However, ecogeomorphological feedbacks (i.e., feedbacks between sediment dynamics and the vegetation community) in freshwater marshes have not received as much attention as within their saltwater counterparts. This study evaluates the role of these feedbacks in stabilizing marsh-surface elevation, relative to sea-level rise, in Dyke Marsh Preserve (Potomac River, USA). Specifically, we relate the composition of the vegetation community to current and historical patterns of sedimentation that occur on bimonthly to decadal time scales. Along with a ~3-year time series of bimonthly and seasonal-scale observations, 210Pb (half-life 22.3 y) profiles are used to identify sites with relatively steady sediment accumulation (i.e., stable sediments) and those with numerous deposition/erosion events (i.e., unstable sediments). Differences in the vegetation community (e.g., composition, stem density) and sediment character (e.g., organic content, grain size) among sites in each of these stability categories are examined with statistical techniques and compared to observations of marsh-surface elevation change. The resulting insights are placed into a geomorphological context to assess the potential response of this marsh to rapid global environmental change.

  1. Modeling downstream fining in sand-bed rivers. I: Formulation

    USGS Publications Warehouse

    Wright, S.; Parker, G.

    2005-01-01

    In this paper a numerical modeling formulation is presented for simulation of the development of the longitudinal profile and bed sediment distribution in sand-bed rivers. The objective of the model application, which is presented in the companion paper (Wright and Parker, 2005), is to study the development of two characteristics of large, low-slope, sand-bed rivers: (1) a downstream decrease in bed slope (i.e. concave upward longitudinal profile) and (2) a downstream decrease in characteristic bed sediment diameter (e.g. the median bed surface size D50). Three mechanisms that lead to an upward concave profile and downstream fining are included in the modeling formulation: (1) a delta prograding into standing water at the downstream boundary, (2) sea-level rise, and (3) tectonic subsidence. In the companion paper (Wright and Parker, 2005) the model is applied to simulate the development of the longitudinal profile and downstream fining in sand-bed rivers flowing into the ocean during the past 5000 years of relatively slow sea-level rise. ?? 2005 International Association of Hydraulic Engineering and Research.

  2. Freshwater foraminiferans revealed by analysis of environmental DNA samples.

    PubMed

    Holzmann, Maria; Habura, Andrea; Giles, Hannah; Bowser, Samuel S; Pawlowski, Jan

    2003-01-01

    Sediment-dwelling protists are among the most abundant meiobenthic organisms, ubiquitous in all types of aquatic ecosystems. Yet, because their isolation and identification are difficult, their diversity remains largely unknown. In the present work, we applied molecular methods to examine the diversity of freshwater Foraminifera, a group of granuloreticulosan protists largely neglected until now. By using specific PCR primers, we detected the presence of Foraminifera in all sediment samples examined. Phylogenetic analysis of amplified SSU rDNA sequences revealed two distinct groups of freshwater foraminiferans. All obtained sequences branched within monothalamous (single-chambered), marine Foraminifera, suggesting a repeated colonization of freshwater environments. The results of our study challenge the traditional view of Foraminifera as essentially marine organisms, and provide a conceptual framework for charting the molecular diversity of freshwater granuloreticulosan protists.

  3. Hydraulic Consequences of Hydrilla, an Invasive Submerged Aquatic Plant, in Freshwater Tidal Channels

    NASA Astrophysics Data System (ADS)

    Jenner, B. A.; Prestegaard, K. L.

    2010-12-01

    Hydrilla is a non-indigenous submerged aquatic plant that has become common in the southeast and mid-Atlantic regions of the United States. The purpose of this research is to evaluate the effects of Hydrilla on flow resistance, velocity, and discharge in freshwater tidal channels along the Patuxent River, MD. Hydrilla height is limited by the level of average low tide in tidal channels; therefore, it has preferentially invaded larger, deeper channels. Geomorphic and hydraulic measurements were made at 6 sites in the channel network of a large, freshwater tidal marsh in the spring, prior to Hydrilla regrowth, and in late summer when vegetation height was at a maximum. Field measurements of vegetation height (Zo), gauge height, energy gradient, velocity profiles, and maximum velocity were used to calculate mean channel velocity, shear velocity, and flow resistance (u/u* and Manning’s n) for the two vegetative conditions. “At-a-station” and “Downstream” hydraulic geometry relationships (the power function relationships of discharge to width, depth, and velocity) were also determined for maximum and minimum vegetation conditions. Results indicate that flow resistance increased and velocity decreased by an order of magnitude between Hydrilla minima and maxima heights. Tidal marsh channels typically exhibit rapid decreases in channel width and cross sectional area in the up-marsh direction. These decreases in width serve to maintain channel velocities and bring sediment, organic matter, and other materials into tidal marshes. Therefore, the downstream hydraulic geometry exponents for width are large and exponents are near zero for velocity, in most measured tidal marsh systems. Our measurements indicate that mean channel velocity decreases significantly in the up-marsh direction during maximum vegetation. This generates an exponent for velocity in the downstream hydraulic geometry relationships that is significantly larger than observed in other tidal systems

  4. Transport, fate and bioremediation of PCBs in freshwater systems

    SciTech Connect

    Birge, W.J.; Price, D.; Robison, A. |

    1995-12-31

    PCB monitoring studies were conducted on four riverine systems that varied in order, gradient, and substrate composition. Accumulation of PCBs was greater in fine-grained sediments with organic carbon content of 1 percent or more. Due to the short residence time of PCBs in water, downstream transport occurred mostly via erosion, suspension and resuspension of sediments and floodplain soils. Residues of PCBs in fish were lowest in the green sunfish and other species, higher in black bass, and highest in bottom feeders, (e.g., channel catfish, carp). Carp and catfish were the poorest indicators of real-time contamination but more useful in assessing historical conditions. Differences in PCB half-life in fish correlated with lipid content. Sunfish were the best indicators of current levels of contamination. PCB body burden in these species decreased markedly after curtailment of PCB outfall. Residues at or above 2 mg/Kg in sunfish decreased to 0.5 mg/Kg or less within 12 to 18 months. Percent tissue lipid was a major factor affecting the rate of metabolic degradation of PCBs in fish. High lipid content may prolong the biological half-life of PCBS, whereas low content may correlate with more rapid degradation, depending on the species. Sunfish, due to their localized range, lower lipid content, and ability to metabolize PCBs may be useful tools in the bioremediation of freshwater systems. They feed largely on primary consumers (e.g. detritivores, herbivores); are adaptable to a wide variety of warm water habitats; and management practices have been well established.

  5. Urbanization and nutrient retention in freshwater riparian wetlands

    USGS Publications Warehouse

    Hogan, D.M.; Walbridge, M.R.

    2007-01-01

    Urbanization can degrade water quality and alter watershed hydrology, with profound effects on the structure and function of both riparian wetlands (RWs) and aquatic ecosystems downstream. We used freshwater RWs in Fairfax County, Virginia, USA, as a model system to examine: (1) the effects of increasing urbanization (indexed by the percentage of impervious surface cover [%ISC] in the surrounding watershed) on nitrogen (N) and phosphorus (P) concentrations in surface soils and plant tissues, soil P saturation, and soil iron (Fe) chemistry; and (2) relationships between RW soil and plant nutrient chemistries vs. the physical and biotic integrity of adjacent streams. Soil total P and NaOH-extractable P (representing P bound to aluminum [Al] and Fe hydrous oxides) varied significantly but nonlinearly with %ISC (r2 = 0.69 and 0.57, respectively); a similar pattern was found for soil P saturation but not for soil total N. Relationships were best described by second-order polynomial equations. Riparian wetlands appear to receive greater P loads in moderately (8.6-13.3% ISC) than in highly (25.1-29.1% ISC) urbanized watersheds. These observations are consistent with alterations in watershed hydrology that occur with increasing urbanization, directing water and nutrient flows away from natural RWs. Significant increases in total and crystalline soil Fe (r 2 = 0.57 and 0.53, respectively) and decreases in relative soil Fe crystallinity with increasing %ISC suggest the mobilization and deposition of terrestrial sediments in RWs, likely due to construction activities in the surrounding watershed. Increases in RW plant tissue nutrient concentrations and %ISC in the surrounding watershed were negatively correlated with standard indices of the physical and biotic integrity of adjacent streams. In combination, these data suggest that nutrient and sediment inputs associated with urbanization and storm-water management are important variables that affect wetland ecosystem services

  6. Urbanization and nutrient retention in freshwater riparian wetlands.

    PubMed

    Hogan, Dianna M; Walbridge, Mark R

    2007-06-01

    Urbanization can degrade water quality and alter watershed hydrology, with profound effects on the structure and function of both riparian wetlands (RWs) and aquatic ecosystems downstream. We used freshwater RWs in Fairfax County, Virginia, USA, as a model system to examine: (1) the effects of increasing urbanization (indexed by the percentage of impervious surface cover [%ISC] in the surrounding watershed) on nitrogen (N) and phosphorus (P) concentrations in surface soils and plant tissues, soil P saturation, and soil iron (Fe) chemistry; and (2) relationships between RW soil and plant nutrient chemistries vs. the physical and biotic integrity of adjacent streams. Soil total P and NaOH-extractable P (representing P bound to aluminum [Al] and Fe hydrous oxides) varied significantly but nonlinearly with % ISC (r2 = 0.69 and 0.57, respectively); a similar pattern was found for soil P saturation but not for soil total N. Relationships were best described by second-order polynomial equations. Riparian wetlands appear to receive greater P loads in moderately (8.6-13.3% ISC) than in highly (25.1-29.1% ISC) urbanized watersheds. These observations are consistent with alterations in watershed hydrology that occur with increasing urbanization, directing water and nutrient flows away from natural RWs. Significant increases in total and crystalline soil Fe (r2 = 0.57 and 0.53, respectively) and decreases in relative soil Fe crystallinity with increasing %ISC suggest the mobilization and deposition of terrestrial sediments in RWs, likely due to construction activities in the surrounding watershed. Increases in RW plant tissue nutrient concentrations and %ISC in the surrounding watershed were negatively correlated with standard indices of the physical and biotic integrity of adjacent streams. In combination, these data suggest that nutrient and sediment inputs associated with urbanization and storm-water management are important variables that affect wetland ecosystem services

  7. Methanogenic archaea diversity in hyporheic sediments of a small lowland stream.

    PubMed

    Brablcová, Lenka; Buriánková, Iva; Badurová, Pavlína; Chaudhary, Prem Prashant; Rulík, Martin

    2015-04-01

    Abundance and diversity of methanogenic archaea were studied at five localities along a longitudinal profile of a Sitka stream (Czech Republic). Samples of hyporheic sediments were collected from two sediment depths (0-25 cm and 25-50 cm) by freeze-core method. Methanogen community was analyzed by fluorescence in situ hybridization (FISH), denaturing gradient gel electrophoresis (DGGE) and sequencing method. The proportion of methanogens to the DAPI-stained cells varied among all localities and depths with an average value 2.08 × 10(5) per g of dry sediment with the range from 0.37 to 4.96 × 10(5) cells per g of dry sediment. A total of 73 bands were detected at 19 different positions on the DGGE gel and the highest methanogen diversity was found at the downstream located sites. There was no relationship between methanogen diversity and sediment depth. Cluster analysis of DGGE image showed three main clusters consisting of localities that differed in the number and similarity of the DGGE bands. Sequencing analysis of representative DGGE bands revealed phylotypes affiliated with members belonging to the orders Methanosarcinales, Methanomicrobiales and Methanocellales. The knowledge about occurrence and diversity of methanogenic archaea in freshwater ecosystems are essential for methane dynamics in river sediments and can contribute to the understanding of global warming process.

  8. Paonia Reservoir Sediment Management

    NASA Astrophysics Data System (ADS)

    Kimbrel, S.; Collins, K.; Williams, C.

    2014-12-01

    Paonia Dam and Reservoir are located on Muddy Creek, a tributary of the North Fork Gunnison River in western Colorado. Since dam closure in 1962, the 2002 survey estimates an annual sedimentation rate of 153,000 m3/y, resulting in a 25% loss of total reservoir capacity. Long before sediment levels completely fill the reservoir, the outlet works have recently plugged with sediment and debris, adversely impacting operations, and emphasizing the urgency of formulating an effective sediment management plan. Starting in 2010-2011, operations were changed to lower the reservoir and flush sediment through the outlet works in early spring before filling the pool for irrigation. Even though the flushing strategy through the long, narrow reservoir (~5 km long and 0.3 km wide) has prevented outlet works plugging, a long term plan is needed to manage inflowing and deposited sediment more efficiently. Reclamation's Sedimentation and River Hydraulics Group is leading an effort to study the past and current sediment issues at Paonia Dam and Reservoir, evaluate feasible sediment management alternatives, and formulate a plan for future operations and monitoring. The study is building on previously collected data and the existing knowledge base to develop a comprehensive, sustainable sediment management plan. The study is being executed in three phases: Phase 1 consisted of an initial site visit to map and sample existing reservoir bottom sediments, a preliminary site evaluation upstream and downstream of the dam, and establishment of time-lapse photo sites and taking initial ground-based photos. Phase 2 includes a bathymetric survey of entire reservoir and 11 km of the river downstream of the dam, continuous suspended sediment monitoring upstream and downstream of the reservoir, and collection of additional core samples of reservoir bottom sediments. Phase 3 involves the evaluation of current and past operations and sediment management practices, evaluate feasible sediment

  9. Trapping of sediment along the Amazon tidal river in diverse floodplain environments

    NASA Astrophysics Data System (ADS)

    Fricke, A. T.; Nittrouer, C. A.; Ogston, A. S.; Nowacki, D. J.; Souza Filho, P. W.; Silveira, O.; Asp, N. E.

    2013-12-01

    The Amazon tidal river, the freshwater reach that is influenced by tides, extends roughly 800 kilometers upstream of the river mouth. Previous studies suggest that up to one third of the sediment measured at the upstream limit of tides does not reach the ocean, and is likely trapped along the tidal river. Here we present data from a variety of depositional environments along this reach, including intertidal vegetated floodplains, floodplain lakes, and drowned tributary confluences. Sediment delivery to each of these environments is temporally variable as a result of changing tides and river stage, and spatially variable along the continuum from the purely fluvial upstream condition to the strongly tidal downstream environment. Short-term instrument records and direct observations are paired with sedimentological and radiochemical techniques to identify mechanisms of sediment exchange between river and floodplain and associated patterns of sediment accumulation. Sediments in vegetated intertidal floodplains exhibit tidal laminations and incised channel networks similar to muddy marine intertidal areas. Floodplain lakes experience dramatic seasonal changes in size, and during high flows of the river skim water and sediment from the Amazon River by providing a shortcut relative to the meandering mainstem. Amazon sediment is fluxed into the drowned tributary confluences (rías) of the Xingu and Tapajos Rivers by density-driven underflows. In the Tapajos Ría, sediment from the Amazon River has built a 25-km long birdfoot delta, suggesting these tributaries may be net sinks of sediment, rather than sources. These findings help define the importance of each tidal environment in trapping Amazon sediment before it reaches the marine environment.

  10. A TOXICITY ASSESSMENT APPROACH TO EVALUATING IN-SITU BIOREMEDIATION OF PAH CONTAMINATED SEDIMENTS

    EPA Science Inventory

    Freshwater and marine sediment toxicity tests were used to measure baseline toxicity of sediment samples collected from New Jersey/New York Harbor (NJ/NY) (non-PAH- contaminated) sediment (ERC). Four freshwater toxicity tests were used: 1) amphipod (Hyalella azteca) mortality and...

  11. Sediment Budgeting in Dam-Affected Rivers: Assessing the Influence of Damming, Tributaries, and Alluvial Valley Sediment Storage on Sediment Regimes

    NASA Astrophysics Data System (ADS)

    Wilcox, A. C.; Dekker, F. J.; Riebe, C. S.

    2014-12-01

    Although sediment supply is recognized as a fundamental driver of fluvial processes, measuring how dams affect sediment regimes and incorporating such knowledge into management strategies remains challenging. To determine the influences of damming, tributary supply, and valley morphology and sediment storage on downstream sediment supply in a dryland river, the Bill Williams River (BWR) in western Arizona, we measured basin erosion rates using cosmogenic nuclide analysis of beryllium-10 (10Be) at sites upstream and downstream of a dam along the BWR, as well as from tributaries downstream of the dam. Riverbed sediment mixing calculations were used to test if the dam, which blocks sediment supply from the upper 85% of the basin's drainage area, increases the proportion of tributary sediment to residual upstream sediment in mainstem samples downstream of the dam. Erosion rates in the BWR watershed are more than twice as large in the upper catchment (136 t km-2 yr-1) than in tributaries downstream of Alamo Dam (61 t km-2 yr-1). Tributaries downstream of the dam have little influence on mainstem sediment dynamics. The effect of the dam on reducing sediment supply is limited, however, because of the presence of large alluvial valleys along the mainstem BWR downstream of the dam that store substantial sediment and mitigate supply reductions from the upper watershed. These inferences, from our 10Be derived erosion rates and mixing calculations, are consistent with field observations of downstream changes in bed material size, which suggest that sediment-deficit conditions are restricted to a 10 km reach downstream of the dam, and limited reservoir bathymetry data. Many studies have suggested that tributary sediment inputs downstream of dams play a key role in mitigating dam-induced sediment deficits, but here we show that in a dryland river with ephemeral tributaries, sediment stored in alluvial valleys can also play a key role and in some cases trumps the role of

  12. Freshwater mussels of Florida

    USGS Publications Warehouse

    Williams, James D.; Butler, Robert S.; Warren, Gary L.; Johnson, Nathan A.

    2014-01-01

    An exhaustive guide to all aspects of the freshwater mussel fauna in Florida,Freshwater Mussels of Florida covers the ecology, biology, distribution, and conservation of the many species of bivalve mollusks in the Sunshine State. In the past three decades, researchers, the public, businesses that depend on wildlife, and policy makers have given more attention to the threatened natural diversity of the Southeast, including freshwater mussels. This compendium meets the increasingly urgent need to catalog this imperiled group of aquatic organisms in the United States.

  13. Adjustment of the San Francisco estuary and watershed to decreasing sediment supply in the 20th century

    USGS Publications Warehouse

    Schoellhamer, David H.; Wright, Scott A.; Drexler, Judith Z.

    2013-01-01

    The general progression of human land use is an initial disturbance (e.g., deforestation, mining, agricultural expansion, overgrazing, and urbanization) that creates a sediment pulse to an estuary followed by dams that reduce sediment supply. We present a conceptual model of the effects of increasing followed by decreasing sediment supply that includes four sequential regimes, which propagate downstream: a stationary natural regime, transient increasing sediment supply, transient decreasing sediment supply, and a stationary altered regime. The model features characteristic lines that separate the four regimes. Previous studies of the San Francisco Estuary and watershed are synthesized in the context of this conceptual model. Hydraulic mining for gold in the watershed increased sediment supply to the estuary in the late 1800s. Adjustment to decreasing sediment supply began in the watershed and upper estuary around 1900 and in the lower estuary in the 1950s. Large freshwater flow in the late 1990s caused a step adjustment throughout the estuary and watershed. It is likely that the estuary and watershed are still capable of adjusting but further adjustment will be as steps that occur only during greater floods than previously experienced during the adjustment period. Humans are actively managing the system to try to prevent greater floods. If this hypothesis of step changes occurring for larger flows is true, then the return interval of step changes will increase or, if humans successfully control floods in perpetuity, there will be no more step changes.

  14. Chemical downstream etching of tungsten

    SciTech Connect

    Blain, M.G.; Jarecki, R.L.; Simonson, R.J.

    1998-07-01

    The downstream etching of tungsten and tungsten oxide has been investigated. Etching of chemical vapor deposited tungsten and e-beam deposited tungsten oxide samples was performed using atomic fluorine generated by a microwave discharge of argon and NF{sub 3}. Etching was found to be highly activated with activation energies approximated to be 6.0{plus_minus}0.5thinspkcal/mol and 5.4{plus_minus}0.4thinspkcal/mol for W and WO{sub 3}, respectively. In the case of F etching of tungsten, the addition of undischarged nitric oxide (NO) directly into the reaction chamber results in the competing effects of catalytic etch rate enhancement and the formation of a nearly stoichiometric WO{sub 3} passivating tungsten oxide film, which ultimately stops the etching process. For F etching of tungsten oxide, the introduction of downstream NO reduces the etch rate. {copyright} {ital 1998 American Vacuum Society.}

  15. Continuous downstream processing of biopharmaceuticals.

    PubMed

    Jungbauer, Alois

    2013-08-01

    Continuous manufacturing has been applied in many different industries but has been pursued reluctantly in biotechnology where the batchwise process is still the standard. A shift to continuous operation can improve productivity of a process and substantially reduce the footprint. Continuous operation also allows robust purification of labile biomolecules. A full set of unit operations is available to design continuous downstream processing of biopharmaceuticals. Chromatography, the central unit operation, is most advanced in respect to continuous operation. Here, the problem of 'batch' definition has been solved. This has also paved the way for implementation of continuous downstream processing from a regulatory viewpoint. Economic pressure, flexibility, and parametric release considerations will be the driving force to implement continuous manufacturing strategies in future.

  16. Continuous downstream processing of biopharmaceuticals.

    PubMed

    Jungbauer, Alois

    2013-08-01

    Continuous manufacturing has been applied in many different industries but has been pursued reluctantly in biotechnology where the batchwise process is still the standard. A shift to continuous operation can improve productivity of a process and substantially reduce the footprint. Continuous operation also allows robust purification of labile biomolecules. A full set of unit operations is available to design continuous downstream processing of biopharmaceuticals. Chromatography, the central unit operation, is most advanced in respect to continuous operation. Here, the problem of 'batch' definition has been solved. This has also paved the way for implementation of continuous downstream processing from a regulatory viewpoint. Economic pressure, flexibility, and parametric release considerations will be the driving force to implement continuous manufacturing strategies in future. PMID:23849674

  17. Effects of ammonia on freshwater mussels in the St. Croix River

    USGS Publications Warehouse

    Newton, Teresa J.

    2004-01-01

    The St. Croix River contains a diverse and abundant group of freshwater mussels. The St. Croix is one of the few rivers in the Midwest not substantially affected by the invasion of the exotic zebra mussel, which encrusts and kills native freshwater mussels. Increased concentrations of ammonia in river sediments, however, poses a significant threat to mussels.

  18. Downstream Yangtze River levels impacted by Three Gorges Dam

    NASA Astrophysics Data System (ADS)

    Wang, Jida; Sheng, Yongwei; Gleason, Colin J.; Wada, Yoshihide

    2013-12-01

    Changes in the Yangtze River level induced by large-scale human water regulation have profound implications on the inundation dynamics of surrounding lakes/wetlands and the integrity of related ecosystems. Using in situ measurements and hydrological simulation, this study reveals an altered Yangtze level regime downstream from the Three Gorges Dam (TGD) to the Yangtze estuary in the East China Sea as a combined result of (i) TGD’s flow regulation and (ii) Yangtze channel erosion due to reduced sediment load. During the average annual cycle of TGD’s regular flow control in 2009-2012, downstream Yangtze level variations were estimated to have been reduced by 3.9-13.5% at 15 studied gauging stations, manifested as evident level decrease in fall and increase in winter and spring. The impacts on Yangtze levels generally diminished in a longitudinal direction from the TGD to the estuary, with a total time lag of ˜9-12 days. Chronic Yangtze channel erosion since the TGD closure has lowered water levels in relation to flows at most downstream stations, which in turn counteracts the anticipated level increase by nearly or over 50% in winter and spring while reinforcing the anticipated level decrease by over 20% in fall. Continuous downstream channel erosion in the near future may further counteract the benefit of increased Yangtze levels during TGD’s water supplement in winter and accelerate the receding of inundation areas/levels of downstream lakes in fall.

  19. Impact of Mississippi River freshwater reintroduction on enhancing marsh accretionary processes in a Louisiana estuary

    NASA Astrophysics Data System (ADS)

    DeLaune, R. D.; Jugsujinda, A.; Peterson, G. W.; Patrick, W. H.

    2003-11-01

    To counteract extensive wetland loss a series of diversion projects have been implemented to introduce freshwater and sediment from the Mississippi River into Louisiana coastal wetlands. To keep pace with increases in water level due to subsidence Louisiana coastal marshes must vertically accrete through the accumulation of both organic matter and mineral sediment. The impact of Mississippi River freshwater diversion on enhancing vertical marsh accretion (mineral and organic matter accumulation) was examined in Breton Sound estuary, a coastal wetland experiencing marsh deterioration as result of subsidence and salt water intrusion. Using 137Cs dating and artificial marker horizons, increases in the rate of vertical marsh accretion were measured at marsh sites along a spatial gradient which has been receiving diverted water from the Mississippi River (Caernarvon diversion) since 1991. Vertical accretion and accumulation of mineral sediment organic matter and nutrients in the marsh soil profile, increased at marsh sites receiving freshwater and sediment input. Iron and manganese content of the marsh surface sediment were shown to be an excellent signature of riverine sediment deposition. Soil extractable phosphorus was higher and extractable sodium was lower at sites nearest freshwater and sediment input. Results demonstrated that freshwater diversion through sediment input and lowering of salinity will enhance marsh accretion and stability, slowing or reversing the rate of wetland loss.

  20. Using chromatography in downstream processing.

    PubMed

    Becker, C

    1989-01-01

    This article concludes the series on the use of chromatography for downstream processing. Although it has only scratched the surface when considering the number of parameters involved in process chromatography, it does give a broad overview including the choice of components through process standards. Pharmacia LKB Biotechnology has had more than 15 years experience in the design development and running of large scale chromatographic processes. During this time the company has gathered a vast amount of experience and information on the key points to successful product purification. Pharmacia LKB can advise on the choice of techniques and the development of a separation process up to full production scale.

  1. DENITRIFICATION AND NITROGEN DYNAMICS IN SEDIMENTS OF A MID-ATLANTIC INCISED STREAM DEPOSITED WITH DEEP LEGACY SEDIMENTS.

    EPA Science Inventory

    Excess legacy sediments deposited in former impounded streams frequently bury Holocene pre-settlement wetlands, decrease in-situ nitrogen removal, and increase nitrogen transport downstream, particularly where deep incised channels limit sediment-water interactions. This has prom...

  2. Modeling downstream fining in sand-bed rivers. II: Application

    USGS Publications Warehouse

    Wright, S.; Parker, G.

    2005-01-01

    In this paper the model presented in the companion paper, Wright and Parker (2005) is applied to a generic river reach typical of a large, sand-bed river flowing into the ocean in order to investigate the mechanisms controlling longitudinal profile development and downstream fining. Three mechanisms which drive downstream fining are studied: a delta prograding into standing water, sea-level rise, and tectonic subsidence. Various rates of sea-level rise (typical of the late Holocene) and tectonic subsidence are modeled in order to quantify their effects on the degree of profile concavity and downstream fining. Also, several other physical mechanisms which may affect fining are studied, including the relative importance of the suspended versus bed load, the effect of the loss of sediment overbank, and the influence of the delta bottom slope. Finally, sensitivity analysis is used to show that the grain-size distribution at the interface between the active layer and substrate has a significant effect on downstream fining. ?? 2005 International Association of Hydraulic Engineering and Research.

  3. ORGANOCHLORINE PESTICIDES AND POLYCHLORINATED BIPHENYLS (PCBS) IN SEDIMENTS AND BIOTA FROM FOUR US ARCTIC LAKES

    EPA Science Inventory

    Organochlorine (OC) concentrations in surface sediment, snails (Lymnea sp.), and two freshwater fish species (grayling, Thymallus arcticus; and lake trout, Salvelinus namaycush) from four lakes in the US Arctic were determined. In surface sediment, chlorinated benzenes (including...

  4. Antibiotic Resistance in Aeromonas Upstream and Downstream of a Water Resource Recovery Facility

    PubMed Central

    Henderson, Samantha K.; Askew, Maegan L.; Risenhoover, Hollie G.; McAndrews, Chrystle R.; Kennedy, S. Dawn; Paine, C. Sue

    2014-01-01

    Aeromonas strains isolated from sediments upstream and downstream of a water resource recovery facility (WRRF) over a two-year time period were tested for susceptibility to thirteen antibiotics. Incidence of resistance to antibiotics, antibiotic resistance phenotypes, and diversity (based on resistance phenotypes) were compared in the two populations. At the beginning of the study, the upstream and downstream Aeromonas populations were different for incidence of antibiotic resistance (p < 0.01), resistance phenotypes (p < 0.005), and diversity. However, these differences declined over time and were not significant at the end of the study. These results (1) indicate that antibiotic resistance in Aeromonas in stream sediments fluctuates considerably over time and (2) suggest that WRRF effluent does not, when examined over the long term, affect antibiotic resistance in Aeromonas in downstream sediment. PMID:25327024

  5. Antibiotic resistance in Aeromonas upstream and downstream of a water resource recovery facility.

    PubMed

    Cisar, Cindy R; Henderson, Samantha K; Askew, Maegan L; Risenhoover, Hollie G; McAndrews, Chrystle R; Kennedy, S Dawn; Paine, C Sue

    2014-09-01

    Aeromonas strains isolated from sediments upstream and downstream of a water resource recovery facility (WRRF) over a two-year time period were tested for susceptibility to 13 antibiotics. Incidence of resistance to antibiotics, antibiotic resistance phenotypes, and diversity (based on resistance phenotypes) were compared in the two populations. At the beginning of the study, the upstream and downstream Aeromonas populations were different for incidence of antibiotic resistance (p < 0.01), resistance phenotypes (p < 0.005), and diversity. However, these differences declined over time and were not significant at the end of the study. These results (1) indicate that antibiotic resistance in Aeromonas in stream sediments fluctuates considerably over time and (2) suggest that WRRF effluent does not, when examined over the long- term, affect antibiotic resistance in Aeromonas in downstream sediment.

  6. Mesozooplankton affinities in a recovering freshwater estuary

    NASA Astrophysics Data System (ADS)

    Chambord, Sophie; Maris, Tom; Colas, Fanny; Van Engeland, Tom; Sossou, Akoko-C.; Azémar, Frédéric; Le Coz, Maïwen; Cox, Tom; Buisson, Laetitia; Souissi, Sami; Meire, Patrick; Tackx, Michèle

    2016-08-01

    Water quality of the Scheldt estuary (Belgium/The Netherlands) has considerably improved in recent years, especially in the upstream, freshwater reaches. Within the zooplankton community, the copepod Eurytemora affinis, typically abundant in brackish water and quasi-absent from freshwater before 2007, has since substantially developed in the latter, where it now represents 90% of the crustacean mesozooplankton community. Simultaneously, cyclopoid copepod abundance has greatly decreased, while cladoceran abundance did not change. The study aim was: 1) to verify if the zooplankton community described for the period 2007-2009 by Mialet et al. (2011) has stabilized until present, and 2) to look for the environmental conditions favouring E. affinis development and causing changes in the upstream freshwater zooplankton community. The 2002-2012 temporal evolution of the zooplankton distribution at three stations in the upstream freshwater Scheldt estuary was analyzed. Water quality remained better after 2007 than before, and some factors revealed continuous improvement in annual mean concentrations (e.g. increase in O2, decrease in BOD5 and NH4sbnd N concentration). The increase in oxygen and the decrease in NH4sbnd N concentration, together with low discharge during summer were the main environmental factors explaining the development and timing of E. affinis in the upstream freshwater reach. In this reach, E. affinis maximal abundance is shifted to higher temperatures (summer) compared to its typical maximum spring abundance peak in the brackish zone of the Scheldt estuary and in most temperate estuaries. The changes in zooplankton community followed a temporal and spatial gradient induced by the spatio-temporal evolution of water quality improvement. The most downstream station (3) allowed E. affinis development (oxygen concentration > 4 mg L-1; NH4sbnd N concentration < 2 mg L-1, discharge (Q) < 50 m3 s-1) from 2007 onwards, and this station showed the highest E

  7. PAH occurrence in chalk river systems from the Jura region (France). Pertinence of suspended particulate matter and sediment as matrices for river quality monitoring.

    PubMed

    Chiffre, Axelle; Degiorgi, François; Morin-Crini, Nadia; Bolard, Audrey; Chanez, Etienne; Badot, Pierre-Marie

    2015-11-01

    This study investigates the variations of polycyclic aromatic hydrocarbon (PAH) levels in surface water, suspended particulate matter (SPM) and sediment upstream and downstream of the discharges of two wastewater treatment plant (WWTP) effluents. Relationships between the levels of PAHs in these different matrices were also investigated. The sum of 16 US EPA PAHs ranged from 73.5 to 728.0 ng L(-1) in surface water and from 85.4 to 313.1 ng L(-1) in effluent. In SPM and sediment, ∑16PAHs ranged from 749.6 to 2,463 μg kg(-1) and from 690.7 μg kg(-1) to 3,625.6 μg kg(-1), respectively. Investigations performed upstream and downstream of both studied WWTPs showed that WWTP discharges may contribute to the overall PAH contaminations in the Loue and the Doubs rivers. Comparison between gammarid populations upstream and downstream of WWTP discharge showed that biota was impacted by the WWTP effluents. When based only on surface water samples, the assessment of freshwater quality did not provide evidence for a marked PAH contamination in either of the rivers studied. However, using SPM and sediment samples, we found PAH contents exceeding sediment quality guidelines. We conclude that sediment and SPM are relevant matrices to assess overall PAH contamination in aquatic ecosystems. Furthermore, we found a positive linear correlation between PAH contents of SPM and sediment, showing that SPM represents an integrating matrix which is able to provide meaningful data about the overall contamination over a given time span.

  8. Freshwater Marsh. Habitat Pac.

    ERIC Educational Resources Information Center

    Fish and Wildlife Service (Dept. of Interior), Washington, DC.

    The materials in this educational packet are designed for use with students in grades 4 through 7. They consist of an overview, three lesson plans and student data sheets, and a poster. The overview describes how the freshwater marsh is an important natural resource for plant, animal, and human populations and how the destruction of marshes causes…

  9. Effects of marine-derived organic matter on fine sediment transport: implications for sediment and nutrient storage in gravel beds. (Invited)

    NASA Astrophysics Data System (ADS)

    Petticrew, E. L.; Rex, J. F.; Albers, S. J.

    2010-12-01

    Fine sediment transport from stream headwaters to downstream estuaries is often mediated by the interaction of sediment with organic matter. Particulate organic matter can move independently downstream or alternately combine via flocculation and aggregation with inorganic sediments. The generation of flocs allows an increase in the channel-bed delivery and retention of both the inorganic and organic portions as these larger particles are more likely to settle or be intercepted by the bed along the channel. The quality of organic matter available in stream systems has been identified as an important factor in the ability of flocs to form in situ. Marine-derived nutrients (MDN) are a significant source of high quality organic matter which is delivered from oceanic environments to freshwater streams as a pulse during carcass decay which follows the in-channel die-off of spawners. A study using a 30 m re-circulating flume simulated the mixing of salmon decay products and fine sediment following the active spawning event. Results indicate that MDN is delivered and retained in gravel beds for up to seven days due to settling and capture of flocs implying that the salmon spawning cycle is an important ecological component of these inland aquatic systems. A salmon-floc feedback loop was postulated emphasizing the significance of salmon actively resuspending sediments during redd building and contributing MDN via decay,such that nutrients are retained in the channel bed for continued productivity. In 2009, a regulated sockeye salmon spawning channel in the Horsefly River (B.C, Canada) was used experimentally to quantify both marine derived nutrients (MDN) and fine sediment trapped by benthic biofilms during salmon spawning and die-off. Biofilm abundance was monitored during salmon arrival, spawning activity and die-off to determine the magnitude of MDN uptake and sediment retention by biofilm. A strong correlation between biofilm abundance and sediment retention indicates

  10. Evidence of local short-distance spawning migration of tropical freshwater eels, and implications for the evolution of freshwater eel migration

    PubMed Central

    Arai, Takaomi

    2014-01-01

    Freshwater eels have fascinated biologists for centuries due to the spectacular long-distance migrations between the eels’ freshwater habitats and their spawning areas far out in the ocean and the mysteries of their ecology. The spawning areas of Atlantic eels and Japanese eel were located far offshore in the Atlantic Ocean and the Pacific Ocean, respectively, and their reproduction took place thousands of kilometers away from their growth habitats. Phylogenetic studies have revealed that freshwater eels originated in the Indonesian region. However, remarkably little is known about the life histories of tropical freshwater eels despite the fact that tropical eels are key to understanding the nature of primitive forms of catadromous migration. This study found spawning-condition tropical freshwater eels in Lake Poso, central Sulawesi, Indonesia, with considerably high gonadosomatic index values and with histologically fully developed gonads. This study provides the first evidence that under certain conditions, freshwater eels have conditions that are immediately able to spawn even in river downstream. The results suggest that, in contrast to the migrations made by the Atlantic and Japanese eels, freshwater eels originally migrated only short distances of <100 kilometers to local spawning areas adjacent to their freshwater growth habitats. Ancestral eels most likely underwent a catadromous migration from local short-distance movements in tropical coastal waters to the long-distance migrations characteristic of present-day temperate eels, which has been well established as occurring in subtropical gyres in both hemispheres. PMID:25614795

  11. Stormwater runoff drives viral community composition changes in inland freshwaters

    PubMed Central

    Williamson, Kurt E.; Harris, Jamie V.; Green, Jasmin C.; Rahman, Faraz; Chambers, Randolph M.

    2014-01-01

    Storm events impact freshwater microbial communities by transporting terrestrial viruses and other microbes to freshwater systems, and by potentially resuspending microbes from bottom sediments. The magnitude of these impacts on freshwater ecosystems is unknown and largely unexplored. Field studies carried out at two discrete sites in coastal Virginia (USA) were used to characterize the viral load carried by runoff and to test the hypothesis that terrestrial viruses introduced through stormwater runoff change the composition of freshwater microbial communities. Field data gathered from an agricultural watershed indicated that primary runoff can contain viral densities approximating those of receiving waters. Furthermore, viruses attached to suspended colloids made up a large fraction of the total load, particularly in early stages of the storm. At a second field site (stormwater retention pond), RAPD-PCR profiling showed that the viral community of the pond changed dramatically over the course of two intense storms while relatively little change was observed over similar time scales in the absence of disturbance. Comparisons of planktonic and particle-associated viral communities revealed two completely distinct communities, suggesting that particle-associated viruses represent a potentially large and overlooked portion of aquatic viral abundance and diversity. Our findings show that stormwater runoff can quickly change the composition of freshwater microbial communities. Based on these findings, increased storms in the coastal mid-Atlantic region predicted by most climate change models will likely have important impacts on the structure and function of local freshwater microbial communities. PMID:24672520

  12. A Downstream voyage with mercury

    USGS Publications Warehouse

    Heinz, Gary

    2016-01-01

    Retrospective essay for the Bulletin of Environmental Contamination and Toxicology.As I look back on my paper, “Effects of Low Dietary Levels of Methyl Mercury on Mallard Reproduction,” published in 1974 in the Bulletin of Environmental Contamination and Toxicology, a thought sticks in my mind. I realize just how much my mercury research was not unlike a leaf in a stream, carried this way and that, sometimes stalled in an eddy, restarted, and carried downstream at a pace and path that was not completely under my control. I was hired in 1969 by the Patuxent Wildlife Research Center to study the effects of environmental pollutants on the behavior of wildlife. A colleague was conducting a study on the reproductive effects of methylmercury on mallards (Anas platyrhynchos), and he offered to give me some of the ducklings. I conducted a pilot study, testing how readily ducklings approached a tape-recorded maternal call. Sample sizes were small, but the results suggested that ducklings from mercury-treated parents behaved differently than controls. That’s how I got into mercury research—pretty much by chance.

  13. A downstream voyage with mercury

    USGS Publications Warehouse

    Heinz, Gary

    2016-01-01

    Retrospective essay for the Bulletin of Environmental Contamination and Toxicology.As I look back on my paper, “Effects of Low Dietary Levels of Methyl Mercury on Mallard Reproduction,” published in 1974 in the Bulletin of Environmental Contamination and Toxicology, a thought sticks in my mind. I realize just how much my mercury research was not unlike a leaf in a stream, carried this way and that, sometimes stalled in an eddy, restarted, and carried downstream at a pace and path that was not completely under my control. I was hired in 1969 by the Patuxent Wildlife Research Center to study the effects of environmental pollutants on the behavior of wildlife. A colleague was conducting a study on the reproductive effects of methylmercury on mallards (Anas platyrhynchos), and he offered to give me some of the ducklings. I conducted a pilot study, testing how readily ducklings approached a tape-recorded maternal call. Sample sizes were small, but the results suggested that ducklings from mercury-treated parents behaved differently than controls. That’s how I got into mercury research—pretty much by chance.

  14. Suspended sediment transport trough a large fluvial-tidal channel network

    USGS Publications Warehouse

    Wright, Scott A.; Morgan, Tara

    2015-01-01

    The confluence of the Sacramento and San Joaquin Rivers, CA, forms a large network of interconnected channels, referred to as the Sacramento-San Joaquin Delta (the Delta). The Delta comprises the transition zone from the fluvial influences of the upstream rivers and tidal influences of San Francisco Bay downstream. Formerly an extensive tidal marsh, the hydrodynamics and geomorphology of Delta have been substantially modified by humans to support agriculture, navigation, and water supply. These modifications, including construction of new channels, diking and draining of tidal wetlands, dredging of navigation channels, and the operation of large pumping facilities for distribution of freshwater from the Delta to other parts of the state, have had a dramatic impact on the physical and ecological processes within the Delta. To better understand the current physical processes, and their linkages to ecological processes, the USGS maintains an extensive network of flow, sediment, and water quality gages in the Delta. Flow gaging is accomplished through use of the index-velocity method, and sediment monitoring uses turbidity as a surrogate for suspended-sediment concentration. Herein, we present analyses of the transport and dispersal of suspended sediment through the complex network of channels in the Delta. The primary source of sediment to the Delta is the Sacramento River, which delivers pulses of sediment primarily during winter and spring runoff events. Upon reaching the Delta, the sediment pulses move through the fluvial-tidal transition while also encountering numerous channel junctions as the Sacramento River branches into several distributary channels. The monitoring network allows us to track these pulses through the network and document the dominant transport pathways for suspended sediment. Further, the flow gaging allows for an assessment of the relative effects of advection (the fluvial signal) and dispersion (from the tides) on the sediment pulses as they

  15. Reclaiming freshwater sustainability in the Cadillac Desert

    PubMed Central

    Sabo, John L.; Sinha, Tushar; Bowling, Laura C.; Schoups, Gerrit H. W.; Wallender, Wesley W.; Campana, Michael E.; Cherkauer, Keith A.; Fuller, Pam L.; Graf, William L.; Hopmans, Jan W.; Kominoski, John S.; Taylor, Carissa; Trimble, Stanley W.; Webb, Robert H.; Wohl, Ellen E.

    2010-01-01

    Increasing human appropriation of freshwater resources presents a tangible limit to the sustainability of cities, agriculture, and ecosystems in the western United States. Marc Reisner tackles this theme in his 1986 classic Cadillac Desert: The American West and Its Disappearing Water. Reisner's analysis paints a portrait of region-wide hydrologic dysfunction in the western United States, suggesting that the storage capacity of reservoirs will be impaired by sediment infilling, croplands will be rendered infertile by salt, and water scarcity will pit growing desert cities against agribusiness in the face of dwindling water resources. Here we evaluate these claims using the best available data and scientific tools. Our analysis provides strong scientific support for many of Reisner's claims, except the notion that reservoir storage is imminently threatened by sediment. More broadly, we estimate that the equivalent of nearly 76% of streamflow in the Cadillac Desert region is currently appropriated by humans, and this figure could rise to nearly 86% under a doubling of the region's population. Thus, Reisner's incisive journalism led him to the same conclusions as those rendered by copious data, modern scientific tools, and the application of a more genuine scientific method. We close with a prospectus for reclaiming freshwater sustainability in the Cadillac Desert, including a suite of recommendations for reducing region-wide human appropriation of streamflow to a target level of 60%. PMID:21149727

  16. Reclaiming freshwater sustainability in the Cadillac Desert.

    PubMed

    Sabo, John L; Sinha, Tushar; Bowling, Laura C; Schoups, Gerrit H W; Wallender, Wesley W; Campana, Michael E; Cherkauer, Keith A; Fuller, Pam L; Graf, William L; Hopmans, Jan W; Kominoski, John S; Taylor, Carissa; Trimble, Stanley W; Webb, Robert H; Wohl, Ellen E

    2010-12-14

    Increasing human appropriation of freshwater resources presents a tangible limit to the sustainability of cities, agriculture, and ecosystems in the western United States. Marc Reisner tackles this theme in his 1986 classic Cadillac Desert: The American West and Its Disappearing Water. Reisner's analysis paints a portrait of region-wide hydrologic dysfunction in the western United States, suggesting that the storage capacity of reservoirs will be impaired by sediment infilling, croplands will be rendered infertile by salt, and water scarcity will pit growing desert cities against agribusiness in the face of dwindling water resources. Here we evaluate these claims using the best available data and scientific tools. Our analysis provides strong scientific support for many of Reisner's claims, except the notion that reservoir storage is imminently threatened by sediment. More broadly, we estimate that the equivalent of nearly 76% of streamflow in the Cadillac Desert region is currently appropriated by humans, and this figure could rise to nearly 86% under a doubling of the region's population. Thus, Reisner's incisive journalism led him to the same conclusions as those rendered by copious data, modern scientific tools, and the application of a more genuine scientific method. We close with a prospectus for reclaiming freshwater sustainability in the Cadillac Desert, including a suite of recommendations for reducing region-wide human appropriation of streamflow to a target level of 60%. PMID:21149727

  17. Reclaiming freshwater sustainability in the Cadillac Desert

    USGS Publications Warehouse

    Sabo, John L.; Sinha, Tushar; Bowling, Laura C.; Schoups, Gerrit H.W.; Wallender, Wesley W.; Campana, Michael E.; Cherkauer, Keith A.; Fuller, Pam L.; Graf, William L.; Hopmans, Jan W.; Kominoski, John S.; Taylor, Carissa; Trimble, Stanley W.; Webb, Robert H.; Wohl, Ellen E.

    2010-01-01

    Increasing human appropriation of freshwater resources presents a tangible limit to the sustainability of cities, agriculture, and ecosystems in the western United States. Marc Reisner tackles this theme in his 1986 classic Cadillac Desert: The American West and Its Disappearing Water. Reisner's analysis paints a portrait of region-wide hydrologic dysfunction in the western United States, suggesting that the storage capacity of reservoirs will be impaired by sediment infilling, croplands will be rendered infertile by salt, and water scarcity will pit growing desert cities against agribusiness in the face of dwindling water resources. Here we evaluate these claims using the best available data and scientific tools. Our analysis provides strong scientific support for many of Reisner's claims, except the notion that reservoir storage is imminently threatened by sediment. More broadly, we estimate that the equivalent of nearly 76% of streamflow in the Cadillac Desert region is currently appropriated by humans, and this figure could rise to nearly 86% under a doubling of the region's population. Thus, Reisner's incisive journalism led him to the same conclusions as those rendered by copious data, modern scientific tools, and the application of a more genuine scientific method. We close with a prospectus for reclaiming freshwater sustainability in the Cadillac Desert, including a suite of recommendations for reducing region-wide human appropriation of streamflow to a target level of 60%.

  18. Reclaiming freshwater sustainability in the Cadillac Desert.

    PubMed

    Sabo, John L; Sinha, Tushar; Bowling, Laura C; Schoups, Gerrit H W; Wallender, Wesley W; Campana, Michael E; Cherkauer, Keith A; Fuller, Pam L; Graf, William L; Hopmans, Jan W; Kominoski, John S; Taylor, Carissa; Trimble, Stanley W; Webb, Robert H; Wohl, Ellen E

    2010-12-14

    Increasing human appropriation of freshwater resources presents a tangible limit to the sustainability of cities, agriculture, and ecosystems in the western United States. Marc Reisner tackles this theme in his 1986 classic Cadillac Desert: The American West and Its Disappearing Water. Reisner's analysis paints a portrait of region-wide hydrologic dysfunction in the western United States, suggesting that the storage capacity of reservoirs will be impaired by sediment infilling, croplands will be rendered infertile by salt, and water scarcity will pit growing desert cities against agribusiness in the face of dwindling water resources. Here we evaluate these claims using the best available data and scientific tools. Our analysis provides strong scientific support for many of Reisner's claims, except the notion that reservoir storage is imminently threatened by sediment. More broadly, we estimate that the equivalent of nearly 76% of streamflow in the Cadillac Desert region is currently appropriated by humans, and this figure could rise to nearly 86% under a doubling of the region's population. Thus, Reisner's incisive journalism led him to the same conclusions as those rendered by copious data, modern scientific tools, and the application of a more genuine scientific method. We close with a prospectus for reclaiming freshwater sustainability in the Cadillac Desert, including a suite of recommendations for reducing region-wide human appropriation of streamflow to a target level of 60%.

  19. Canine adenovirus downstream processing protocol.

    PubMed

    Puig, Meritxell; Piedra, Jose; Miravet, Susana; Segura, María Mercedes

    2014-01-01

    Adenovirus vectors are efficient gene delivery tools. A major caveat with vectors derived from common human adenovirus serotypes is that most adults are likely to have been exposed to the wild-type virus and exhibit active immunity against the vectors. This preexisting immunity limits their clinical success. Strategies to circumvent this problem include the use of nonhuman adenovirus vectors. Vectors derived from canine adenovirus type 2 (CAV-2) are among the best-studied representatives. CAV-2 vectors are particularly attractive for the treatment of neurodegenerative disorders. In addition, CAV-2 vectors have shown great promise as oncolytic agents in virotherapy approaches and as vectors for recombinant vaccines. The rising interest in CAV-2 vectors calls for the development of scalable GMP compliant production and purification strategies. A detailed protocol describing a complete scalable downstream processing strategy for CAV-2 vectors is reported here. Clarification of CAV-2 particles is achieved by microfiltration. CAV-2 particles are subsequently concentrated and partially purified by ultrafiltration-diafiltration. A Benzonase(®) digestion step is carried out between ultrafiltration and diafiltration operations to eliminate contaminating nucleic acids. Chromatography purification is accomplished in two consecutive steps. CAV-2 particles are first captured and concentrated on a propyl hydrophobic interaction chromatography column followed by a polishing step using DEAE anion exchange monoliths. Using this protocol, high-quality CAV-2 vector preparations containing low levels of contamination with empty viral capsids and other inactive vector forms are typically obtained. The complete process yield was estimated to be 38-45 %. PMID:24132487

  20. Sustainably Managing Sediment in Regulated Rivers: Recent Developments

    NASA Astrophysics Data System (ADS)

    Kondolf, G. M.; Gao, Y.; Annandale, G. W.; Morris, G. L.; Sumi, T.

    2014-12-01

    Inspired by the current drought and concerns about maintaining water storage capacity, California State Senate this year passed SB1259, directing the Department of Water Resources to assess the state's reservoirs for sedimentation problems. The need to actively manage sediment in reservoirs is increasingly recognized, as valuable reservoir storage capacity is lost and downstream reaches suffer from sediment starvation, manifesting problems such as channel incision, accelerated erosion of deltas, and loss of gravels important for habitat. With increased dam construction globally, these impacts will be widespread. Despite the opportunities to pass sediment through or around reservoirs (to preserve reservoir capacity and to minimize downstream impacts), these sustainable approaches to managing sediment are not applied in many situations where they would be effective. From a workshop involving international and Chinese experts and review of recent literature, collective global experience in managing reservoir sediments and mitigating downstream sediment starvation suggest that sediment management can be classified as catchment management (to reduce sediment inflow), sediment removal, and sediment routing through or around the reservoir. Sediment routing has the virtues of maintaining sediment flows to downstream reaches, as well as preserving reservoir capacity. Where geometry is favorable, sediment can often be bypassed around the reservoir (avoiding reservoir sedimentation and supplying sediment to downstream reaches) or sluiced through large-capacity outlets after flowing rapidly through the reservoir to avoid sedimentation. In narrow reservoirs with steep longitudinal gradients, sediments accumulated in the reservoir can often be re-suspended and flushed through when the reservoir is drawn down. Turbidity currents can often be 'vented' through the dam, with the advantage that the reservoir need not be drawn down to pass sediment. In planning dams, the expert group

  1. Acidification of freshwaters

    SciTech Connect

    Cresser, M.S.; Edwards, A.C.

    1987-01-01

    This volume gives an account that draws not only on the main branches of chemistry but also on soil physics, chemistry, hydrology, meteorology, geography, geology, plant physiology, soil microbiology and zoology. The author examine the numerous interacting physical, chemical, and biological, processes that regulate the acidity of freshwaters, a phenomenon that has various causes, including precipitation; acidifying pollutions; and the interaction of plants, soils and water. The relative importance of the different processes is examined.

  2. Freshwater wetlands and wildlife

    SciTech Connect

    Sharitz, R.R.; Gibbons, J.W.

    1989-01-01

    This volume is a product of the Freshwater Wetlands and Wildlife symposium held in Charleston, South Carolina, on March 24--27, 1986 and contains 94 papers. The stimulus for the symposium came from our interest in augmenting the findings of the long-term research programs on freshwater wetlands and wildlife that have been carried out on the US Department of Energy's Savannah River Site in South Carolina. The symposium provided a forum on an international scale for the exchange of data about freshwater ecosystems: their functions, uses, and their future. The papers in this volume address issues related to natural, man-managed, and degraded ecosystems. The volume is divided into two sections. The first section deals with the functions and values of wetlands, including their use as habitat for plants and animals, their role in trophic dynamics, and their basic processes. The second section treats the subject of their status and management, including techniques for assessing their value, laws for protecting them, and plans for properly managing them. Individual papers will be indexed and entered separately on the energy data base.

  3. Anomalous Sediment Mixing by Bioturbation

    NASA Astrophysics Data System (ADS)

    Roche, K. R.; Aubeneau, A. F.; Xie, M.; Packman, A. I.

    2013-12-01

    Bioturbation, the reworking of sediments by animals and plants, is the dominant mode of sediment mixing in low-energy environments, and plays an important role in sedimentary biogeochemical processes. Mixing resulting from bioturbation has historically been modeled as a diffusive process. However, diffusion models often do not provide a sufficient description of sediment mixing due to bioturbation. Stochastic models, such as the continuous time random walk (CTRW) model, provide more general descriptions of mixing behavior that are applicable even when regular diffusion assumptions are not met. Here we present results from an experimental investigation of anomalous sediment mixing by bioturbation in freshwater sediments. Clean and heavy-metal-contaminated sediments were collected from Lake DePue, a backwater lake of the Illinois River. The burrowing worm species Lumbriculus variegatus was introduced to homogenized Lake DePue sediments in aerated aquaria. We then introduced inert fine fluorescent particles to the sediment-water interface. Using time-lapse photography, we observed the mixing of the fluorescent particles into the sediment bed over a two-week period. We developed image analysis software to characterize the concentration distribution of the fluorescent particles as a function of sediment depth, and applied this to the time-series of images to evaluate sediment mixing. We fit a one-dimensional CTRW model to the depth profiles to evaluate the underlying statistical properties of the mixing behavior. This analysis suggests that the sediment mixing caused by L. variegatus burrowing is subdiffusive in time and superdiffusive in space. We also found that heavy metal contamination significantly reduces L. variegatus burrowing, causing increasingly anomalous sediment mixing. This result implies that there can be important feedbacks between sediment chemistry, organism behavior, and sediment mixing that are not considered in current environmental models.

  4. Linking Short-term Upstream and Downstream Geomorphic Responses to the Removal of Condit Dam, White Salmon River, Washington

    NASA Astrophysics Data System (ADS)

    Wilcox, A. C.; O'Connor, J. E.; Major, J. J.; Coloaiacomo, E.

    2013-12-01

    Dynamiting a hole at the base of the 38-m-high Condit Dam, on the White Salmon River, Washington, resulted in rapid reservoir drainage and erosion and produced a downstream surge of water and sediment. To document the short-term upstream and downstream responses to the October 2011 Condit breach, we combined photographic methods, topographic surveys, stage and suspended sediment measurements, and stratigraphic observations. Initial reservoir erosion occurred as a result of mass failure of thick, fine-grained reservoir sediment, which was eventually supplemented by knickpoint migration as the erosion propagated upstream from the dam. About 10 percent of total reservoir sediment eroded in the first 90 minutes after the breach, and about one-third of the reservoir sediment had evacuated in the first week. Downstream, an initially sediment-poor discharge peak with an approximately 100-year recurrence interval was followed by a hyperconcentrated sediment pulse (32% by volume) that locally produced meters-thick sand deposits. The post-breach sediment dynamics at Condit were in many respects more analogous to sediment pulses introduced by volcanic eruptions or large mass failure events than by previous dam removals.

  5. Effects of pollution on freshwater organisms

    SciTech Connect

    Phipps, G.L.; Harden, M.J.; Leonard, E.N.; Roush, T.H; Spehar, D.L.; Stephan, C.E.; Pickering, Q.H.; Buikema, A.L. Jr.

    1984-06-01

    This review includes subjects in last year's reviews on effects of pollution on freshwater invertebrates and effects of pollution on freshwater fish and amphibians. This review also includes information on the effects of pollution on freshwater plants. 625 references.

  6. The use of carbon resin for the reduction of sediment toxicity to infaunal amphipods

    SciTech Connect

    Hurk, P. van den; Vogelbein, M.A.; McCullough, D.; Roberts, M.H. Jr.

    1995-12-31

    Commercially available carbon resins are designed to absorb non-polar organic compounds. To evaluate the potential of resins to absorb hydrophobic pore water pollutants and thus reduce the toxicity of sediments the Ambersorb 1500 resin was mixed with PAH-contaminated sediment samples and tested with infaunal amphipods. The sediments were collected at a freshwater site in the Little Scioto River, OH and at an estuarine site in the Elisabeth River, VA. The bulk chemical analysis of both sediments was comparable in that they both show creosote pollution. The sediments were tested in dilution series with clean reference sediments and with increasing amounts of resin (2, 4 and 8% dry sediment weight). The freshwater sediments were tested with both Hyalella azteca (a freshwater infaunal amphipod) and Leptocheirus plumulosus (an estuarine infaunal amphipod). The estuarine sediments were only tested with L. plumulosus. Significant effects of the resin were recognized by comparing polluted sediment LC50s with their 95% confidence intervals, as calculated with the Trimmed Spearman-Karber test. The results show that the freshwater samples were not very toxic to either of the species (LC50: 80--100% polluted sediment), and there was no significant effect of the resin. The estuarine samples were highly toxic (LC50: 3--13% polluted sediment) and there was a significant reduction of toxicity with increasing amount of resin. Pore water chemical analysis will be evaluated to explain the toxicity differences between the freshwater and estuarine samples.

  7. Freshwater biodiversity: importance, threats, status and conservation challenges.

    PubMed

    Dudgeon, David; Arthington, Angela H; Gessner, Mark O; Kawabata, Zen-Ichiro; Knowler, Duncan J; Lévêque, Christian; Naiman, Robert J; Prieur-Richard, Anne-Hélène; Soto, Doris; Stiassny, Melanie L J; Sullivan, Caroline A

    2006-05-01

    because it is influenced by the upstream drainage network, the surrounding land, the riparian zone, and - in the case of migrating aquatic fauna - downstream reaches. Such prerequisites are hardly ever met. Immediate action is needed where opportunities exist to set aside intact lake and river ecosystems within large protected areas. For most of the global land surface, trade-offs between conservation of freshwater biodiversity and human use of ecosystem goods and services are necessary. We advocate continuing attempts to check species loss but, in many situations, urge adoption of a compromise position of management for biodiversity conservation, ecosystem functioning and resilience, and human livelihoods in order to provide a viable long-term basis for freshwater conservation. Recognition of this need will require adoption of a new paradigm for biodiversity protection and freshwater ecosystem management - one that has been appropriately termed 'reconciliation ecology'.

  8. Freshwater biodiversity: importance, threats, status and conservation challenges.

    PubMed

    Dudgeon, David; Arthington, Angela H; Gessner, Mark O; Kawabata, Zen-Ichiro; Knowler, Duncan J; Lévêque, Christian; Naiman, Robert J; Prieur-Richard, Anne-Hélène; Soto, Doris; Stiassny, Melanie L J; Sullivan, Caroline A

    2006-05-01

    because it is influenced by the upstream drainage network, the surrounding land, the riparian zone, and - in the case of migrating aquatic fauna - downstream reaches. Such prerequisites are hardly ever met. Immediate action is needed where opportunities exist to set aside intact lake and river ecosystems within large protected areas. For most of the global land surface, trade-offs between conservation of freshwater biodiversity and human use of ecosystem goods and services are necessary. We advocate continuing attempts to check species loss but, in many situations, urge adoption of a compromise position of management for biodiversity conservation, ecosystem functioning and resilience, and human livelihoods in order to provide a viable long-term basis for freshwater conservation. Recognition of this need will require adoption of a new paradigm for biodiversity protection and freshwater ecosystem management - one that has been appropriately termed 'reconciliation ecology'. PMID:16336747

  9. Recent Advances in Studies of Coastal Marsh Sedimentation

    NASA Astrophysics Data System (ADS)

    Pasternack, G. B.; Leonard, L. A.

    2001-05-01

    Limited understanding of sedimentation processes in coastal marshes is a key constraint on the management of environmental impacts associated with sea level rise, degrading quality and quantity of aquatic habitats, and downstream impacts of watershed land use. The problem is exacerbated by complex interactions among physical, ecological, and chemical variables that impact sedimentation over a large range of spatio-temporal scales. These challenges are being met by increasingly sophisticated approaches which cross-fertilize from other disciplines or go even further to integrate multidisciplinary perspectives. One example of the former has been improved precision of fine scale measurements of fluid mechanics and sediment transport over marsh plains and application of those measurements in geomorphologic and coastal engineering models. This advancement has improved our understanding of marsh dynamics at a mechanistic level, which is key for improving the predictive capabilities of wetland models. An example of a multidisciplinary approach that has become very common is the combined usage of multiple monitoring, isotopic, and palynological methods for estimating sedimentation and erosion at a site over a range of time scales. By applying such combinations, it has been possible to piece apart the relative roles of natural processes such as sea level rise and storms from human impacts such as flow constrictions, channel dredging, and sediment supply changes. Beyond improving approaches used to study marshes, past work has led to new questions about marsh morphodynamics and how coastal marshes interact with upland watersheds. With the aid of chaos theory, some recent studies have asserted that coastal marsh channels are fractal and thus must follow universal laws in common with watershed drainages and other dendritic systems. Also, where marshes exist among a mosaic of habitats on a delta, research has revealed the relative roles of watershed versus coastal processes in

  10. Sediment delivery after a wildfire

    USGS Publications Warehouse

    Reneau, S.L.; Katzman, D.; Kuyumjian, G.A.; Lavine, A.; Malmon, D.V.

    2007-01-01

    We use a record of sedimentation a small reservoir within the Cerro Grande burn area, New Mexico, to document postfire delivery of ash, other fine-grained sediment carried in suspension within floods, and coarse-grained sediment transported as bedload over a five-year period. Ash content of sediment layers is estimated using fallout 137Cs as a tracer, and ash concentrations are shown to rapidly decrease through a series of moderate-intensity convective storms in the first rainy season after the fire. Over 90% of the ash was delivered to the reservoir in the first year, and ash concentrations in suspended sediment were negligible after the second year. Delivery of the remainder of the fine sediment also declined rapidly after the first year despite the occurrence of higher-intensity storms in the second year. Fine sediment loads after five years remained significantly above prefire averages. Deposition of coarse-grained sediment was irregular in time and was associated with transport by snowmelt runoff of sediment stored along the upstream channel during short-duration summer floods. Coarse sediment delivery in the first four years was strongly correlated with snowmelt volume, suggesting a transport-limited system with abundant available sediment. Transport rates of coarse sediment declined in the fifth year, consistent with a transition to a more stable channel as the accessible sediment supply was depleted and the channel bed coarsened. Maximum impacts from ash and other fine-grained sediment therefore occurred soon after the fire, whereas the downstream impacts from coarse-grained sediment were attenuated by the more gradual process of bedload sediment transport. ?? 2007 Geological Society of America.

  11. Arctic freshwater synthesis: Introduction

    NASA Astrophysics Data System (ADS)

    Prowse, T.; Bring, A.; Mârd, J.; Carmack, E.

    2015-11-01

    In response to a joint request from the World Climate Research Program's Climate and Cryosphere Project, the International Arctic Science Committee, and the Arctic Council's Arctic Monitoring and Assessment Program, an updated scientific assessment has been conducted of the Arctic Freshwater System (AFS), entitled the Arctic Freshwater Synthesis (AFSΣ). The major reason for joint request was an increasing concern that changes to the AFS have produced, and could produce even greater, changes to biogeophysical and socioeconomic systems of special importance to northern residents and also produce extra-Arctic climatic effects that will have global consequences. Hence, the key objective of the AFSΣ was to produce an updated, comprehensive, and integrated review of the structure and function of the entire AFS. The AFSΣ was organized around six key thematic areas: atmosphere, oceans, terrestrial hydrology, terrestrial ecology, resources and modeling, and the review of each coauthored by an international group of scientists and published as separate manuscripts in this special issue of Journal of Geophysical Research-Biogeosciences. This AFSΣ—Introduction reviews the motivations for, and foci of, previous studies of the AFS, discusses criteria used to define the domain of the AFS, and details key characteristics of the definition adopted for the AFSΣ.

  12. Hydrology and sediment dynamics above and below the St. Croix Falls dam, MN/WI

    NASA Astrophysics Data System (ADS)

    MacGregor, K. R.; Hornbach, D.; Hove, M.

    2011-12-01

    Sediment budgets in river networks are notoriously difficult to construct but key for quantifying both short and long-term changes to fluvial environments. Hydrologic and sedimentologic conditions in the St. Croix River, one of the first rivers in the US to be designated a National Wild and Scenic River, play a significant role in the stability of native freshwater mussel populations. The availability and transport of sediment controls overall geomorphology, riverbed composition, and water turbidity, all of which are important to mussel habitat. Mussel habitat analyses show a decrease in the grain size of bed sediment and a >90% decline in the juvenile mussel population in the last decade, but only in a region below the St. Croix Falls dam. This reach of the St. Croix River is home to two federally endangered mussel species; we need to better understand the controls on sediment transport into and out of this stretch of river to understand the causes for the mussel decline, and to evaluate future threats to these species. In conjunction with mussel habitat analyses, we collected surface and near-bed suspended sediment, as well as bedload transport samples below the dam. Since January 2008 we have collected suspended sediment samples weekly at four locations, two above the dam and two below. Comparison to data collected in the 1970's suggests a decrease in suspended sediment, although the frequency of summer/fall high flow events has increased. We measured near-bed sediment transport using a BL-84 bedload sampler at Wild River, a sandy habitat upstream of the St. Croix Falls dam and Interstate Park, a rockier habitat downstream of the dam. A significant relationship was found between water discharge and bed sediment transport at both high (>5000 cfs) and low flows at both sites. Using historical maps and recent bathymetric data, we used GIS to construct changes in reservoir volume over time. Our results indicate that there has been substantial sediment infilling

  13. Marine and freshwater toxins.

    PubMed

    Hungerford, James M

    2006-01-01

    In a very busy and exciting year, 2005 included First Action approval of a much needed official method for paralytic shellfish toxins and multiple international toxin symposia highlighted by groundbreaking research. These are the first-year milestones and activities of the Marine and Freshwater Toxins Task Force and Analytical Community. Inaugurated in 2004 and described in detail in last year's General Referee Report (1) this international toxins group has grown to 150 members from many regions and countries. Perhaps most important they are now making important and global contributions to food safety and to providing alternatives to animal-based assays. Official Method 2005.06 was first approved in late 2004 by the Task Force and subsequently Official First Action in 2005 (2) by the Methods Committee on Natural Toxins and Food Allergens and the Official Methods Board. This nonproprietary method (3) is a precolumn oxidation, liquid chromatographic method that makes good use of fluorescence detection to provide high sensitivity detection of the saxitoxins. It has also proven to be rugged enough for regulatory use and the highest level of validation. As pointed out in the report of method principle investigator and Study Director James Lawrence, approval of 2005.06 now provides the first official alternative to the mouse bioassay after many decades of shellfish monitoring. This past year in April 2005 the group also held their first international conference, "Marine and Freshwater Toxins Analysis: Ist Joint Symposium and AOAC Task Force Meeting," in Baiona, Spain. The 4-day conference consisted of research and stakeholder presentations and symposium-integrated subgroup sessions on ciguatoxins, saxitoxin assays and liquid chromatography (LC) methods for saxitoxins and domoic acids, okadaiates and azaspiracids, and yessotoxins. Many of these subgroups were recently formed in 2005 and are working towards their goals of producing officially validated analytical methods

  14. Sperm in "parhenogenetic" freshwater gastrotrichs.

    PubMed

    Weiss, M J; Levy, D P

    1979-07-20

    Freshwater members of the phylum Gastrotricha have been considered obligate parthenogens. In Lepidodermelia squammata, the species for which there is most evidence for parthenogenesis, sperm have been discovered. This finding will necessitate reexamination of the nature of sexuality and life cycles and of the concept of "species" in freshwater gastrotrichs. PMID:17747043

  15. Sperm in "parhenogenetic" freshwater gastrotrichs.

    PubMed

    Weiss, M J; Levy, D P

    1979-07-20

    Freshwater members of the phylum Gastrotricha have been considered obligate parthenogens. In Lepidodermelia squammata, the species for which there is most evidence for parthenogenesis, sperm have been discovered. This finding will necessitate reexamination of the nature of sexuality and life cycles and of the concept of "species" in freshwater gastrotrichs.

  16. New Zealand sediment toxicity testing methodologies

    SciTech Connect

    Hickey, C.W.; Roper, D.S.; Nipper, M.; Martin, M.L.

    1995-12-31

    Sediment toxicity testing in New Zealand is developing against a background of an increasing public desire for environmental protection and strict legislative requirements that contaminant discharges should not have any significant adverse effects on aquatic life. The importance of sediment contamination and its potential immediate and long term adverse effects on aquatic biota in general is becoming widely recognized, This has lead to an effort to develop acute and chronic sediment toxicity tests with organisms representative of the New Zealand indigenous biota. An amphipod species occurring in both freshwater and estuarine environments, Chaetocorophium cf lucasi, and the marine bivalve Macomona liliana, a common inhabitant of intertidal sandflats, have been evaluated for their sensitivity to natural sediment characteristics. The amphipod and bivalve are presently being used for testing sediment acute (10d) and chronic toxicity (20--30d), with survival and growth as test endpoints, and the bivalve has shown to be a useful organism for behavioral tests with burial and sediment avoidance by movement and drifting as endpoints. The estuarine bivalve Arthritica bifurca, abundant in muddy sediments, is a self-fertilizing hermaphroditic species and its suitability for sediment tests with a reproductive endpoint is underway. Freshwater sphaeriid bivalves, Sphaerium novazelandiae, are also being used for survival, growth, reproduction and behavioral endpoints. Sensitivity to reference toxicants and results for contaminated sediments will be presented and discussed in relation to sediment quality criteria developed elsewhere.

  17. Chronic effects of contaminated sediment on Daphnia magna and Chironomus tentans (journal version)

    SciTech Connect

    Nebeker, A.V.; Onjukka, S.T.; Cairns, M.A.

    1988-01-01

    Chronic tests were conducted with Daphnia magna (cladoceran) and Chironomus tentans (midge) to determine their usefulness as test organisms for chronic sediment assays, and to estimate the potential long-term impact of contaminated freshwater sediments and contaminated Superfund-site soils on freshwater invertebrates. These two species were used successfully in acute sediment tests and were shown to be useful in chronic tests in water.

  18. Chronic effects of contaminated sediment on Daphnia magna and Chironomus tentans

    SciTech Connect

    Nebeker, A.V.; Onjukka, S.T.; Cairns, M.A.

    1988-10-01

    Chronic tests were conducted with Daphnia magna (cladoceran) and Chironomus tentans (midge) to determine their usefulness as test organisms for chronic sediment assays, and to estimate the potential long-term impact of contaminated freshwater sediments and contaminated Superfund site soils on freshwater invertebrates. These two species have been used successfully in acute sediment tests, and have been shown to be useful in chronic tests in water--only bioassays.

  19. Phosphorus accumulation and eutrophication in feed-supply freshwater fishponds.

    PubMed

    Zhang, Ming-kui; Fang, Li-ping

    2006-01-01

    The rapid growth and intensification of freshwater fishery can cause imbalances between phosphorus (P) input in feed and its output in produce. This aquaculture can result in enriching exogenous P in fishponds and, consequently, accelerates the process of eutrophication. To assess relations among input, accumulation, release of P and as a consequence degrading water quality in terms of chlorophyll-a (Chl-a) in freshwater fishponds, fourteen fishponds with feed supply, nine fishponds without feed supply, and five non-fish ponds in Shaoxing Plain, southeast China were selected for comparing P accumulation in their waters and surface sediments. Surface sediment samples were collected from each pond to evaluate their total P, water soluble P, Olsen P, algal available P, and P fractions. Water samples were also collected from the ponds to measure concentrations of dissolved P and Chl-a. Total P in the sediments ranged from 0.88 to 1.73 g/kg in the fishponds with feed supply, that in the non-fish ponds ranged from 0.47 to 0.86 g/kg. Organic P, accounted for 23% to 60% of total P in the sediments, was an important P fraction and increased linearly with increasing organic matter. Long-term application of feeds resulted in increased P availability in the bottom sediments and degradation of water quality in the freshwater fishponds. Compared with non-fish ponds, sediments from the feed-supplied fishponds contained considerably higher Olsen P, algal available P, and water soluble P. Higher proportions of the labile P (NH4Cl-P) and potentially labile P (NaOH-IP) were also found in the sediments from the fishponds. High solubility of P in the sediments resulted in elevation of P and chlorophyll-a concentration in the pond water. The dissolved P concentration in the pond water increased in the order of non-fish ponds (12 microg/L) < fishponds without feed supply (24 microg/L) < fishponds with feed supply (66 microg/L). Linear correlations between concentrations of total P, Olsen

  20. Downstream channel adjustment in a low-relief, glacially conditioned watershed

    NASA Astrophysics Data System (ADS)

    Thayer, James B.; Phillips, Roger T. J.; Desloges, Joseph R.

    2016-06-01

    River management practices are often informed by theoretical expectations of downstream channel adjustment, which may not be valid in low relief, glacially conditioned watersheds such as those in the lower North American Great Lakes region. Downstream trends in channel morphology and bed material size within a low-relief, glacially conditioned watershed are explored here and compared to a theoretical watershed model where slope and grain size are expected to decline exponentially. The observed channel morphology is then tested against a theoretical concept of reach-scale channel grade. The downstream hydraulic geometry relations wbf ∝ Qbf0.51S- 0.02 and dbf ∝ Qbf0.32S- 0.21 were found to best describe downstream changes in channel morphology and are consistent with some prior studies. Bed material size varies irregularly down the channel. Slope-controlled downstream fining trends are evident where inputs from glacial materials and tributaries are negligible but are masked by cobble/boulder lag deposits where the channel is cut into these glacial deposits. The asynchronous variability in slope and grain size produces downstream variations in graded and nongraded, understeepened conditions separated at τ*ex = 0. Graded reaches exist where τ*ex > 0, but an upper boundary with nongraded, oversteepened reaches is less clear. The results emphasize the geomorphic legacy of inherited slopes and sediment sources in dictating the modern downstream patterns of fluvial characteristics and morphologies in glacially conditioned, and similarly complex, watersheds.

  1. Morphology and Sediment Transport Dynamics of the Selenga River Delta, Lake Baikal, Russia

    NASA Astrophysics Data System (ADS)

    Dong, T. Y.; Il'icheva, L.; Nittrouer, J. A.; Pavolv, M.

    2013-12-01

    The Selenga River fan delta is a lacustrine system located in southeastern Siberia, Russia, where Selenga River flows into Lake Baikal. The Selenga River is the largest source of sediment and water entering Lake Baikal. Covering ~550 km2, the Selenga delta is one of the largest freshwater deltas in the world. Evaluating the Selenga delta and its morphology is very important for local residents who rely upon the delta for both ecological and agricultural welfare. However, a sediment budget remains poorly constrained, as do estimates for the partitioning of water and sediment amongst the numerous bifurcating delta channels. This information is critical for addressing how the delta morphology evolves and influences the stratigraphic composition of the delta. To investigate the morphological characteristics of the delta, a field expedition was undertaken during July 2013 in collaboration with Russian scientists. The overall goal of the field work was to constrain delta dynamics through data collection. Field measurements included single-beam bathymetry data and sidescan sonar data to characterize: 1) channel geometries of the delta; 2) bedform sizes and distribution; and 3) grain-size composition of the channel bed. Flow velocity measurements were collected within the bifurcating channels to measure water discharge. Bedload samples were obtained within the active distributary channels to measure downstream sediment fining. Additionally, channel island cores were collected in order to analyze the internal architecture of the delta. The data reveal a systematic downstream sediment fining, from a predominantly gravel bed near the delta apex, to a fine-sand bed at the delta-lake interface (~40 km total distance). Bathymetry data document how width-to-depth ratios systematically decrease downstream in association with increasing channel bifurcations and decreasing channel-bed grain size. Furthermore, the investigations reveal that the delta is actively terraced, with the

  2. Modern Reservoir Sedimentation Management Techniques with Examples

    NASA Astrophysics Data System (ADS)

    Annandale, G. W.

    2014-12-01

    Implementation of reservoir sedimentation management approaches results in a win-win scenario, it assists in enhancing the environment by preserving river function downstream of dams while concurrently providing opportunities to sustainably manage water resource infrastructure. This paper summarizes the most often used reservoir sedimentation management techniques with examples of where they have been implemented. Three categories can be used to classify these technologies, i.e. catchment management, sediment routing and sediment removal. The objective of catchment management techniques is to minimize the amount of sediment that may discharge into a reservoir, thereby reducing the loss of storage space due to sedimentation. Reservoir routing is a set of techniques that aim at minimizing the amount of sediment that may deposit in a reservoir, thereby maximizing the amount of sediment that may be passed downstream. The third group consists of techniques that may be used to remove previously deposited sediment from reservoirs. The selection of reservoir sedimentation management approaches is site specific and depends on various factors, including dam height, reservoir volume, reservoir length, valley shape, valley slope, sediment type and hydrology. Description of the different reservoir sedimentation management techniques that are used in practice will be accompanied by case studies, including video, illustrating criteria that may be used to determine the potential success of implementing the techniques.

  3. Management and the conservation of freshwater ecosystems

    USGS Publications Warehouse

    Wipfli, Mark S.; Richardson, John S.

    2015-01-01

    Riparian and freshwater ecosystems are typically tightly coupled, especially in their natural states, and the linkages that couple them frequently exert strong influence on their associated invertebrate and fish fauna (e.g. Gregory et al., 1991; Naiman et al., 2010). Riparian habitats, and the condition of these habitats, further plays a key role in the ecology of these fresh waters, influencing critical processes such as water, nutrient and sediment delivery and dynamics; prey resources for fish and other consumers, and other organic materials exchanged between aquatic and terrestrial habitats (Nakano et al., 1999; Naiman et al., 2010); light and water temperature dynamics that in turn affect food web processes and fish metabolism and growth; aquatic physical habitat (wood); and terrestrial consumers that prey upon fishes (Bisson & Bilby, 1998; Naiman et al., 2010; Wipfli & Baxter, 2010). These processes in turn directly or indirectly influence fishes in freshwater systems (Wang et al., 2001; Pusey & Arthington, 2003; Allan, 2004; Richardson et al., 2010a).

  4. Geomorphic response of rivers to glacial retreat and increasing peak flows downstream from Mount Rainier, Washington

    NASA Astrophysics Data System (ADS)

    Czuba, J. A.; Barnas, C. R.; Magirl, C. S.; Voss, F. D.

    2010-12-01

    On Mount Rainier, Washington, the National Park Service has documented widespread aggradation of as much as 10 m since the early 20th century, of rivers draining the glaciated stratovolcano. This rapid sedimentation appears to be related to glacial retreat and also may be a function of the increased magnitude and timing of peak flows that mobilize and transport sediment. We are conducting an assessment of the Puget Lowland rivers that drain Mount Rainier, 25-100 km downstream from the park boundary, to document the geomorphic response of the downstream reaches given the widespread aggradation upstream. These downstream reaches provide critical aquatic habitat for spawning and rearing of several species of salmonids, including endangered Chinook salmon and steelhead. Fluvial sedimentation can have both deleterious and beneficial effects on aquatic habitat depending on sediment particle size, river slope and width, and river management. To date, our work shows sedimentation of as much as 2 m between 1984 and 2009 in these lowland rivers. Aggradation rates that were calculated by comparing channel change at 156 cross sections, ranged between 4.8 and 9.1 cm/yr in reaches where rivers exit the mountain front and enter the lowland. Analysis of streamflow-gaging station data from throughout the watersheds draining Mount Rainier show rapid incision and aggradation, suggesting pulses of coarse-grained bedload may be moving down the mountainous rivers as kinetic waves. Preliminary results, however, seem to indicate that the rivers in the Puget Lowland have not yet experienced significant widespread sedimentation directly related to glacial retreat. Estimating the time of arrival of mobilized alluvium is a critical need for resource managers given the potential effects of sedimentation on river flood-conveyance capacity, fish habitat, and estuarine wetlands.

  5. Arctic Ocean freshwater as a trigger for abrupt climate change

    NASA Astrophysics Data System (ADS)

    Bradley, Raymond; Condron, Alan; Coletti, Anthony

    2016-04-01

    The cause of the Younger Dryas cooling remains unresolved despite decades of debate. Current arguments focus on either freshwater from Glacial Lake Agassiz drainage through the St Lawrence or the MacKenzie river systems. High resolution ocean modeling suggests that freshwater delivered to the North Atlantic from the Arctic Ocean through Fram Strait would have had more of an impact on Atlantic Meridional Overturning Circulation (AMOC) than freshwater from the St Lawrence. This has been interpreted as an argument for a MacKenzie River /Lake Agassiz freshwater source. However, it is important to note that although the modeling identifies Fram Strait as the optimum location for delivery of freshwater to disrupt the AMOC, this does not mean the freshwater source came from Lake Agassiz. Another potential source of freshwater is the Arctic Ocean ice cover itself. During the LGM, ice cover was extremely thick - many tens of meters in the Canada Basin (at least), resulting in a hiatus in sediment deposition there. Extreme ice thickness was related to a stagnant circulation, very low temperatures and continuous accumulation of snow on top of a base of sea-ice. This resulted in a large accumulation of freshwater in the Arctic Basin. As sea-level rose and a more modern circulation regime became established in the Arctic, this freshwater was released from the Arctic Ocean through Fram Strait, leading to extensive sea-ice formation in the North Atlantic (Greenland Sea) and a major reduction in the AMOC. Here we present new model results and a review of the paleoceanographic evidence to support this hypothesis. The bottom line is that the Arctic Ocean was likely a major player in causing abrupt climate change in the past, via its influence on the AMOC. Although we focus here on the Younger Dryas, the Arctic Ocean has been repeatedly isolated from the world ocean during glacial periods of the past. When these periods of isolation ended, it is probable that there were significant

  6. Microbial Sulfate Reduction Enhances Arsenic Mobility Downstream of Zerovalent-Iron-Based Permeable Reactive Barrier.

    PubMed

    Kumar, Naresh; Couture, Raoul-Marie; Millot, Romain; Battaglia-Brunet, Fabienne; Rose, Jérôme

    2016-07-19

    We assessed the potential of zerovalent-iron- (Fe(0)) based permeable reactive barrier (PRB) systems for arsenic (As) remediation in the presence or absence of microbial sulfate reduction. We conducted long-term (200 day) flow-through column experiments to investigate the mechanisms of As transformation and mobility in aquifer sediment (in particular, the PRB downstream linkage). Changes in As speciation in the aqueous phase were monitored continuously. Speciation in the solid phase was determined at the end of the experiment using X-ray absorption near-edge structure (XANES) spectroscopy analysis. We identified thio-As species in solution and AsS in solid phase, which suggests that the As(V) was reduced to As(III) and precipitated as AsS under sulfate-reducing conditions and remained as As(V) under abiotic conditions, even with low redox potential and high Fe(II) content (4.5 mM). Our results suggest that the microbial sulfate reduction plays a key role in the mobilization of As from Fe-rich aquifer sediment under anoxic conditions. Furthermore, they illustrate that the upstream-downstream linkage of PRB affects the speciation and mobility of As in downstream aquifer sediment, where up to 47% of total As initially present in the sediment was leached out in the form of mobile thio-As species. PMID:27309856

  7. Microbial Sulfate Reduction Enhances Arsenic Mobility Downstream of Zerovalent-Iron-Based Permeable Reactive Barrier.

    PubMed

    Kumar, Naresh; Couture, Raoul-Marie; Millot, Romain; Battaglia-Brunet, Fabienne; Rose, Jérôme

    2016-07-19

    We assessed the potential of zerovalent-iron- (Fe(0)) based permeable reactive barrier (PRB) systems for arsenic (As) remediation in the presence or absence of microbial sulfate reduction. We conducted long-term (200 day) flow-through column experiments to investigate the mechanisms of As transformation and mobility in aquifer sediment (in particular, the PRB downstream linkage). Changes in As speciation in the aqueous phase were monitored continuously. Speciation in the solid phase was determined at the end of the experiment using X-ray absorption near-edge structure (XANES) spectroscopy analysis. We identified thio-As species in solution and AsS in solid phase, which suggests that the As(V) was reduced to As(III) and precipitated as AsS under sulfate-reducing conditions and remained as As(V) under abiotic conditions, even with low redox potential and high Fe(II) content (4.5 mM). Our results suggest that the microbial sulfate reduction plays a key role in the mobilization of As from Fe-rich aquifer sediment under anoxic conditions. Furthermore, they illustrate that the upstream-downstream linkage of PRB affects the speciation and mobility of As in downstream aquifer sediment, where up to 47% of total As initially present in the sediment was leached out in the form of mobile thio-As species.

  8. Modeling grain size adjustments in the downstream reach following run-of-river development

    NASA Astrophysics Data System (ADS)

    Fuller, Theodore K.; Venditti, Jeremy G.; Nelson, Peter A.; Palen, Wendy J.

    2016-04-01

    Disruptions to sediment supply continuity caused by run-of-river (RoR) hydropower development have the potential to cause downstream changes in surface sediment grain size which can influence the productivity of salmon habitat. The most common approach to understanding the impacts of RoR hydropower is to study channel changes in the years following project development, but by then, any impacts are manifest and difficult to reverse. Here we use a more proactive approach, focused on predicting impacts in the project planning stage. We use a one-dimensional morphodynamic model to test the hypothesis that the greatest risk of geomorphic change and impact to salmon habitat from a temporary sediment supply disruption exists where predevelopment sediment supply is high and project design creates substantial sediment storage volume. We focus on the potential impacts in the reach downstream of a powerhouse for a range of development scenarios that are typical of projects developed in the Pacific Northwest and British Columbia. Results indicate that increases in the median bed surface size (D50) are minor if development occurs on low sediment supply streams (<1 mm for supply rates 1 × 10-5 m2 s-1 or lower), and substantial for development on high sediment supply streams (8-30 mm for supply rates between 5.5 × 10-4 and 1 × 10-3 m2 s-1). However, high sediment supply streams recover rapidly to the predevelopment surface D50 (˜1 year) if sediment supply can be reestablished.

  9. Wave-Induced Groundwater Flows in a Freshwater Beach Aquifer

    NASA Astrophysics Data System (ADS)

    Malott, S. S.; Robinson, C. E.; O'Carroll, D. M.

    2014-12-01

    Wave-induced recirculation across the sediment-water interface can impact the transport of pollutants through a beach aquifer and their ultimate flux into coastal waters. The fate of nutrients (e.g. from septic and agricultural sources) and fecal indicator bacteria (e.g. E. coil) near the sediment-water interface are of particular concern as these pollutants often lead to degradation of recreational water quality and nearshore ecosystems. This paper presents detailed field measurements of groundwater flows in a freshwater beach aquifer on Lake Huron over periods of intensified wave conditions. Quantifying wave-driven processes in a freshwater beach aquifer enables wave effects to be studied in isolation from density and tidal effects that complicate groundwater flows in marine beaches. Water exchange across the sediment-water interface and groundwater flow patterns were measured using groundwater wells, arrays of vertically nested pressure transducers and manometers. Results show that wave action induces rapid infiltration/exfiltration across the sediment-water interface and a larger recirculation cell through the beach aquifer. Field data is used to validate a numerical groundwater model of wave-induced groundwater flows. While prior studies have simulated the effects of waves on beach groundwater flows, this study is the first attempt to validate these sophisticated modeling approaches. Finally, field data illustrating the impact of wave-induced groundwater flows on nutrient and bacteria fate and transport in beach aquifers will also be presented.

  10. An estimation of radiation doses to benthic invertebrates from sediments collected near a Canadian uranium mine.

    PubMed

    Thomas, P; Liber, K

    2001-10-01

    A new method is described for calculating radiation doses to benthic invertebrates from radionuclide concentrations in freshwater sediment. Both internal and external radiation doses were estimated for all 14 principal radionuclides of the uranium-238 decay series. Sediments were collected from three sites downstream of a uranium mining operation in northern Saskatchewan, Canada. Sediments from two sites, located approximately 1.6 and 4.4 km downstream from mining operations, yielded absorbed doses to both larval midges, Chironomus tentans, and adult amphipods, Hyalella azteca, of 59-60 and 19 mGy/year, respectively, compared to 3.2 mGy/year for a nearby control site. External beta radiation from protactinium-234 (234Pa) and alpha radiation from uranium (U) contributed most of the dose at the impacted sites, whereas polonium-210 (210Po) was most important at the control site. If a weighting factor of 20 was employed for the greater biological effect of alpha vs. beta and gamma radiation, then total equivalent doses rose to 540-560 mGy/year at the site closest to uranium operations. Such equivalent doses are above the 360-mGy/year no-observed-effect level for reproductive effects in vertebrates from gamma radiation exposure. Data are not available to determine the effect of such doses on benthic organisms, but they are high enough to warrant concern. Detrimental effects have been observed in H. azteca at similar uranium concentration in laboratory toxicity tests, but it remains unclear whether the radiotoxicity or the chemotoxicity of uranium is responsible for these effects.

  11. An estimation of radiation doses to benthic invertebrates from sediments collected near a Canadian uranium mine.

    PubMed

    Thomas, P; Liber, K

    2001-10-01

    A new method is described for calculating radiation doses to benthic invertebrates from radionuclide concentrations in freshwater sediment. Both internal and external radiation doses were estimated for all 14 principal radionuclides of the uranium-238 decay series. Sediments were collected from three sites downstream of a uranium mining operation in northern Saskatchewan, Canada. Sediments from two sites, located approximately 1.6 and 4.4 km downstream from mining operations, yielded absorbed doses to both larval midges, Chironomus tentans, and adult amphipods, Hyalella azteca, of 59-60 and 19 mGy/year, respectively, compared to 3.2 mGy/year for a nearby control site. External beta radiation from protactinium-234 (234Pa) and alpha radiation from uranium (U) contributed most of the dose at the impacted sites, whereas polonium-210 (210Po) was most important at the control site. If a weighting factor of 20 was employed for the greater biological effect of alpha vs. beta and gamma radiation, then total equivalent doses rose to 540-560 mGy/year at the site closest to uranium operations. Such equivalent doses are above the 360-mGy/year no-observed-effect level for reproductive effects in vertebrates from gamma radiation exposure. Data are not available to determine the effect of such doses on benthic organisms, but they are high enough to warrant concern. Detrimental effects have been observed in H. azteca at similar uranium concentration in laboratory toxicity tests, but it remains unclear whether the radiotoxicity or the chemotoxicity of uranium is responsible for these effects. PMID:11686646

  12. PROCEDURES FOR THE DERIVATION OF EQUILIBRIUM PARTITIONING SEDIMENT BENCHMARKS (ESBS) FOR THE PROTECTION OF BENTHIC ORGANISMS: COMPENDIUM OF TIER 2 VALUES FOR NONIONIC ORGANICS

    EPA Science Inventory

    This equilibrium partitioning sediment benchmark (ESB) document describes procedures to derive concentrations for 32 nonionic organic chemicals in sediment which are protective of the presence of freshwater and marine benthic organisms. The equilibrium partitioning (EqP) approach...

  13. The origin, composition, and reactivity of dissolved iron(III) complexes in coastal organic- and iron-rich sediments

    NASA Astrophysics Data System (ADS)

    Beckler, Jordon S.; Jones, Morris E.; Taillefert, Martial

    2015-03-01

    The redox chemistry and speciation of Fe in both solid and dissolved phases were characterized in the organic- and Fe-rich sediments of the Satilla River estuary in South-East Georgia (USA) on a series of four cruises between July 2007 and January 2008. Results indicate that dissolved Fe is present in relatively high concentration in the overlying waters at the freshwater end of the estuary and flocculates along the river as the salinity increases downstream. Soluble organic-Fe(III) complexes comprise the majority of dissolved Fe (<0.2 μm) in the suboxic pore waters of the upriver stations that are characterized by high concentrations of poorly crystalline Fe(III) (oxy)hydroxides. In contrast, SO42--reducing conditions downstream prevent the accumulation of organic-Fe(III) in the pore waters by titrating Fe from the sediment. Separation of dissolved Fe by size exclusion chromatography revealed that Fe(II) is complexed by organic ligands in the pore waters while the organic-Fe(III) complexes are either small or highly reactive with the column matrix. Finally, dissimilatory Fe(III) reduction, stimulated by inoculating anaerobic sediments with a Fe(III)-reducing bacterium (FeRB), Shewanella putrefaciens strain 200, increased production of soluble organic-Fe(III) complexes, and addition of reactive Fe(III) hydroxides accelerated the non-reductive dissolution of Fe(III) (oxy)hydroxides irrespective of the presence of exogenous FeRB. These findings suggest soluble organic-Fe(III) complexes in suboxic pore waters may be produced both as intermediates during the dissimilatory reduction of Fe(III) (oxy)hydroxides by Fe(III)-reducing microorganisms and during the oxidation of organic-Fe(II) complexes by Fe(III) (oxy)hydroxides. These soluble organic-Fe(III) complexes are stable in pore waters and may flux from the sediments to the continental shelf.

  14. Comparative Geomorphology of Salt and Tidal Freshwater Marsh Environments

    NASA Astrophysics Data System (ADS)

    Pasternack, G. B.

    2002-05-01

    Temperate estuaries include a spectrum of coastal marshes ranging from highly saline near the ocean to fresh in tributaries with substantial watershed drainage. While the hydrologic, sedimentary, and geomorphic dynamics of salt marshes have been thoroughly investigated, those aspects of tidal freshwater marshes have only begun to be addressed. Based on a recent burst in research on tidal freshwater systems in Chesapeake Bay by different universities, an attempt is made here to provide comparative geomorphology. In terms of similarities, both have tidal channels whose hydraulic geometry is primarily controlled by the tidal prism. Both show decreasing sedimentation and increasing organics with elevation and distance from channels. At seasonal to interannual time scales, the morphodynamics of both show similarities in the interplay among hydroperiod, vegetation, and geomorphology. Rather than simply evolving from youth to maturity, both systems exhibit strong evidence for dynamic equilibrium between process and morphology. Despite these similarities, there are key differences that motivate further research of tidal freshwater marshes. First, whereas salt marshes are limited by sediment supply, tidal fresh ones may not be limited depending on upstream basin size. E.g., fringing marshes along Pumunkey River have very low sediment supply, while deltaic marshes in Bush River and Sassafras River are not supply-limited. Instead, the growth of deltaic fresh marshes is transport limited, as winds and tides can only generate low momentum and turbulence for sediment transport. As illustrated in multiple systems, a constant availability of sediment leads to higher sedimentation in fresh marshes. Second, in high latitude salt marshes where the tidal range is large and the climate cold, ice acts as a strong erosional agent. In fresh marshes, ice serves to sequester sediment and buffer the erosional impact of autumnal vegetation dieback. Third, the high spatial variation in plant

  15. Philippines' downstream sector poised for growth

    SciTech Connect

    Not Available

    1992-05-11

    This paper reports that the Philippines' downstream sector is poised for sharp growth. Despite a slip in refined products demand in recent years, Philippines products demand will rebound sharply by 2000, East-West Center (EWC), Honolulu, predicts. Philippines planned refinery expansions are expected to meet that added demand, EWC Director Fereidun Fesharaki says. Like the rest of the Asia-Pacific region, product specifications are changing, but major refiners in the area expect to meet the changes without major case outlays. At the same time, Fesharaki says, push toward deregulation will further bolster the outlook for the Philippines downstream sector.

  16. Accounting for Long Term Sediment Storage in a Watershed Scale Numerical Model for Suspended Sediment Routing

    NASA Astrophysics Data System (ADS)

    Keeler, J. J.; Pizzuto, J. E.; Skalak, K.; Karwan, D. L.; Benthem, A.; Ackerman, T. R.

    2015-12-01

    Quantifying the delivery of suspended sediment from upland sources to downstream receiving waters is important for watershed management, but current routing models fail to accurately represent lag times in delivery resulting from sediment storage. In this study, we route suspended sediment tagged by a characteristic tracer using a 1-dimensional model that implicitly includes storage and remobilization processes and timescales. From an input location where tagged sediment is added, the model advects suspended sediment downstream at the velocity of the stream (adjusted for the intermittency of transport events). Deposition rates are specified by the fraction of the suspended load stored per kilometer of downstream transport (presumably available from a sediment budget). Tagged sediment leaving storage is evaluated from a convolution equation based on the probability distribution function (pdf) of sediment storage waiting times; this approach avoids the difficulty of accurately representing complex processes of sediment remobilization from floodplain and other deposits. To illustrate the role of storage on sediment delivery, we compare exponential and bounded power-law waiting time pdfs with identical means of 94 years. In both cases, the median travel time for sediment to reach the depocenter in fluvial systems less than 40km long is governed by in-channel transport and is unaffected by sediment storage. As the channel length increases, however, the median sediment travel time reflects storage rather than in-channel transport; travel times do not vary significantly between the two different waiting time functions. At distances of 50, 100, and 200 km, the median travel time for suspended sediment is 36, 136, and 325 years, orders of magnitude slower than travel times associated with in-channel transport. These computations demonstrate that storage can be neglected for short rivers, but for longer systems, storage controls the delivery of suspended sediment.

  17. SEDIMENT TOXICITY IDENTIFICATION EVALUATION (TIE)PHASE I,II,III GUIDANCE DOCUMENT

    EPA Science Inventory

    Sediment contamination in the United States has been amply documented and, in order to comply with the 1972 Clean Water Act, the U.S. Environmental Protection Agency must address the issue of toxic sediments. Contaminated sediments from a number of freshwater and marine sites hav...

  18. Proposed sediment quality criteria for the protection of benthic organisms: Dieldrin

    SciTech Connect

    Hansen, D.J.; Berry, W.J.; Di Toro, D.M.; Paquin, P.; Davanzo, L.

    1991-11-01

    The criteria presented in the document are the EPA's best recommendation of the concentrations of a substance in sediment that will not unacceptably affect benthic organisms. These criteria are applicable to a variety of freshwater and marine sediments because they are based on the biologically available concentration of dieldrin in sediments.

  19. A TOXICITY ASSESSMENT APPROACH FOR THE EVALUATION OF IN-SITU BIOREMEDIATION OF PAH CONTAMINATED SEDIMENTS

    EPA Science Inventory

    Freshwater and marine sediment toxicity test were used to measure baseline toxicity of sediment samples collected from New York/New Jersey Harbor (NY/NJH) and East River (ER) (PAH contaminated) sediments and to determine the effectiveness of the developed biotreatment strategies ...

  20. Sediment properties influencing the bioavailability of uranium to Chironomus dilutus larvae in spiked field sediments.

    PubMed

    Crawford, Sarah E; Liber, Karsten

    2016-04-01

    The partitioning of metals between dissolved and solid phases directly affects metal bioavailability to benthic invertebrates and is influenced by metal-binding properties of sediment phases. Little research has been done examining the effects of sediment properties on the bioavailability of uranium (U) to freshwater benthic invertebrates. In the present study, 18 field sediments with a wide range of properties (total organic carbon, fine fraction, cation exchange capacity, and iron content) were amended with the same concentrations of U to characterize the effects of these sediment properties on U bioavailability to freshwater midge, Chironomus dilutus. Bioaccumulation of U by C. dilutus larvae varied by over an order of magnitude when exposed to sediments spiked with 50 mg U kg(-1) d.w. (5-69 mg U kg(-1) d.w.) and 500 mg U kg(-1) d.w. (20-452 mg U kg(-1) d.w.), depending on the type of sediment. Variance in U bioaccumulation was best explained by differences in the cation exchange capacity, fine fraction (≤50 μm particle size), and Fe content of U-spiked sediment, with generated regression equations predicting observed bioaccumulation within a factor of two. The presented regression equations offer an easy-to-apply method for accounting for the influence of sediment properties on U bioavailability in freshwater sediment, with fine fraction being the single most practical variable. This research strongly supports that risk assessments and guidelines for U-contaminated sediments should not ignore the influence of sediment properties that can result in substantial differences in the bioaccumulation of U in benthic invertebrates. PMID:26802266

  1. Sediment properties influencing the bioavailability of uranium to Chironomus dilutus larvae in spiked field sediments.

    PubMed

    Crawford, Sarah E; Liber, Karsten

    2016-04-01

    The partitioning of metals between dissolved and solid phases directly affects metal bioavailability to benthic invertebrates and is influenced by metal-binding properties of sediment phases. Little research has been done examining the effects of sediment properties on the bioavailability of uranium (U) to freshwater benthic invertebrates. In the present study, 18 field sediments with a wide range of properties (total organic carbon, fine fraction, cation exchange capacity, and iron content) were amended with the same concentrations of U to characterize the effects of these sediment properties on U bioavailability to freshwater midge, Chironomus dilutus. Bioaccumulation of U by C. dilutus larvae varied by over an order of magnitude when exposed to sediments spiked with 50 mg U kg(-1) d.w. (5-69 mg U kg(-1) d.w.) and 500 mg U kg(-1) d.w. (20-452 mg U kg(-1) d.w.), depending on the type of sediment. Variance in U bioaccumulation was best explained by differences in the cation exchange capacity, fine fraction (≤50 μm particle size), and Fe content of U-spiked sediment, with generated regression equations predicting observed bioaccumulation within a factor of two. The presented regression equations offer an easy-to-apply method for accounting for the influence of sediment properties on U bioavailability in freshwater sediment, with fine fraction being the single most practical variable. This research strongly supports that risk assessments and guidelines for U-contaminated sediments should not ignore the influence of sediment properties that can result in substantial differences in the bioaccumulation of U in benthic invertebrates.

  2. Downstream dilution of a lahar: transition from debris flow to hyperconcentrated streamflow.

    USGS Publications Warehouse

    Pierson, T.C.; Scott, K.M.

    1985-01-01

    Nearly instantaneous melting of snow and ice by the March 19, 1982, eruption of Mount St. Helens, released a 4 X 106 m3 flood of water from the crater that was converted to a lahar (volcanic debris flow) through erosion and incorporation of sediment by the time it reached the base of the volcano. Over the next 81 km that it traveled down the Toutle River, the flood wave was progressively diluted through several mechanisms. A transformation from debris flow to hyperconcentrated streamflow began to occur about 27 km downstream from the crater, when the total sediment concentration had decreased to about 78% by weight (57% by volume).-from Authors

  3. Modeling tidal freshwater marsh sustainability in the Sacramento-San Joaquin Delta under a broad suite of potential future scenarios

    USGS Publications Warehouse

    Swanson, Kathleen M.; Drexler, Judith Z.; Fuller, Christopher C.; Schoellhamer, David H.

    2015-01-01

    In this paper, we report on the adaptation and application of a one-dimensional marsh surface elevation model, the Wetland Accretion Rate Model of Ecosystem Resilience (WARMER), to explore the conditions that lead to sustainable tidal freshwater marshes in the Sacramento–San Joaquin Delta. We defined marsh accretion parameters to encapsulate the range of observed values over historic and modern time-scales based on measurements from four marshes in high and low energy fluvial environments as well as possible future trends in sediment supply and mean sea level. A sensitivity analysis of 450 simulations was conducted encompassing a range of eScholarship provides open access, scholarly publishing services to the University of California and delivers a dynamic research platform to scholars worldwide. porosity values, initial elevations, organic and inorganic matter accumulation rates, and sea-level rise rates. For the range of inputs considered, the magnitude of SLR over the next century was the primary driver of marsh surface elevation change. Sediment supply was the secondary control. More than 84% of the scenarios resulted in sustainable marshes with 88 cm of SLR by 2100, but only 32% and 11% of the scenarios resulted in surviving marshes when SLR was increased to 133 cm and 179 cm, respectively. Marshes situated in high-energy zones were marginally more resilient than those in low-energy zones because of their higher inorganic sediment supply. Overall, the results from this modeling exercise suggest that marshes at the upstream reaches of the Delta—where SLR may be attenuated—and high energy marshes along major channels with high inorganic sediment accumulation rates will be more resilient to global SLR in excess of 88 cm over the next century than their downstream and low-energy counterparts. However, considerable uncertainties exist in the projected rates of sea-level rise and sediment avail-ability. In addition, more research is needed to constrain future

  4. [Geographic variations in freshwater molluscs].

    PubMed

    Vinarskiĭ, M V

    2012-01-01

    The phenomenon of geographic variation is known in practically all taxa of living beings. However, the reality of this phenomenon in freshwater molluscs (snails and bivalves) has many times been questioned in the past. It was accepted that these animals do not demonstrate spatially-oriented variation, where specific "local race" is arisen in each specific habitat. Till the beginning of 1970s, there was no statistical evidence that geographic clines in freshwater molluscs really exist. However, a few species of freshwater molluscs has been studied in this respect so far, therefore it is almost impossible to draw any general patterns of geographical variation in this group of animals. Most species of freshwater molluscs studied to the date exhibit statistically significant decrease of their body size in the south-north direction. Perhaps, it may be explained by decrease of the duration of the growth season in high latitudes. Some species of freshwater snails demonstrate clinal changes in shell proportions. This allows to reject subspecies separation within these species since diagnostic characters of such "subspecies" may blur when geographic variation is taken into consideration. The data on geographic variation in anatomical traits in freshwater molluscs is much more scarce. At least one species of pond snails (Lymnaea terebra) demonstrates clinal variation in proportions of the copulative apparatus in the south-north direction. Further studies of geographic variation in freshwater molluscs should reveal whether it is truly adaptive, i.e. whether geographical clines have underlying genetic basis. Otherwise, the clines may arise as a result of direct modifying effect of a habitat.

  5. STABLE NITROGEN ISOTOPES AS INDICATORS OF ANTHOPOGENIC ACTIVITIES IN SMALL FRESHWATER SYSTEMS

    EPA Science Inventory

    Stable nitrogen isotope ratios ( 15N) were measured in fish, mussel, and sediment samples taken from 17 small freshwater sites to examine food chain length and trophic position across sites affected by differing levels of anthropogenic activity. Both shoreline development and fis...

  6. Assessment of mercury and methylmercury in water, sediment, and biota in Sulphur Creek in the vicinity of the Clyde Gold Mine and the Elgin Mercury Mine, Colusa County, California

    USGS Publications Warehouse

    Hothem, Roger L.; Rytuba, James J.; Brussee, Brianne E.; Goldstein, Daniel N.

    2013-01-01

    At the request of the U.S. Bureau of Land Management, we performed a study during April–July 2010 to characterize mercury (Hg), monomethyl mercury (MMeHg), and other geochemical constituents in sediment, water, and biota at the Clyde Gold Mine and the Elgin Mercury Mine, located in neighboring subwatersheds of Sulphur Creek, Colusa County, California. This study was in support of a Comprehensive Environmental Response, Compensation, and Liability Act - Removal Site Investigation. The investigation was in response to an abatement notification from the California Central Valley Regional Water Quality Control Board to evaluate the release of Hg from the Clyde and Elgin mines. Samples of water, sediment, and biota (aquatic macroinvertebrates) were collected from sites upstream and downstream from the two mine sites to evaluate the level of Hg contamination contributed by each mine to the aquatic ecosystem. Physical parameters, as well as dissolved organic carbon, total Hg (HgT), and MMeHg were analyzed in water and sediment. Other relevant geochemical constituents were analyzed in sediment, filtered water, and unfiltered water. Samples of aquatic macroinvertebrates from each mine were analyzed for HgT and MMeHg. The presence of low to moderate concentrations of HgT and MMeHg in water, sediment, and biota from the Freshwater Branch of Sulphur Creek, and the lack of significant increases in these concentrations downstream from the Clyde Mine indicated that this mine is not a significant source of Hg to the watershed during low flow conditions. Although concentrations of HgT and MMeHg were generally higher in samples of sediment and water from the Elgin Mine compared to the Clyde Mine, concentrations in comparable biota from the two mine areas were similar. It is likely that highly saline effluent from nearby hot springs contribute more Hg to the West Fork of Sulphur Creek than the mine waste material at the Elgin Mine.

  7. Morphodynamics, stratigraphy, and sediment transport patterns of the Kennebec River estuary, Maine, USA

    NASA Astrophysics Data System (ADS)

    Fenster, M. S.; FitzGerald, D. M.

    1996-12-01

    Sediment transport and circulation patterns within the lower Kennebec River estuary, Maine (˜20 km) have been investigated over a two year and nine month period using fathometer profiles and side-scan sonograms in conjunction with flow measurements, fresh-water discharge data, and grain-size data. The geologic history of the estuary is inferred from high-resolution seismic profiles and bridge borings. Subbottom data corroborate a five-stage evolutionary history that has been determined for other areas of the west-central Maine coast. Scattered deposits of glacial till (diamict) and stratified drift overly a Precambrian to Paleozoic metasedimentary bedrock basement. The glacio-marine blue clay of the Presumpscot Formation unconformably overlies the diamict and drift and drapes the basement, where till is absent. The clay surface is an erosional unconformity formed during the last sea-level lowstand. During subsequent sea-level rise, a relatively coarse-grained estuarine fill was deposited within a flood-dominated, relatively large paleo-Kennebec River estuary. As the rates of sea-level rise slowed, the system shifted to an ebb-dominated estuary in which the estuarine fill underwent reworking and downstream net transport. Bathymetric data show a hierarchical arrangement of bedforms ranging in size and morphology from well-developed, ebb-oriented transverse bars to superimposed simple, straight-crested megaripples. The transverse bars were stable over the study period. The reworking and migration of the smaller forms are closely linked to seasonal variations in the relative contributions between tidal flow and fresh-water discharge. During the spring, large-magnitude discharge events augment ebb-tidal flows. The ebb-reinforced flows dominate the system and result in a net downstream transport of medium- to coarse-grained sand. Estuarine stratification plays an important role in sediment transport during non-spring months. From mid-summer to fall, salinity gradients

  8. Measuring benefits of protected area management: trends across realms and research gaps for freshwater systems.

    PubMed

    Adams, Vanessa M; Setterfield, Samantha A; Douglas, Michael M; Kennard, Mark J; Ferdinands, Keith

    2015-11-01

    Protected areas remain a cornerstone for global conservation. However, their effectiveness at halting biodiversity decline is not fully understood. Studies of protected area benefits have largely focused on measuring their impact on halting deforestation and have neglected to measure the impacts of protected areas on other threats. Evaluations that measure the impact of protected area management require more complex evaluation designs and datasets. This is the case across realms (terrestrial, freshwater, marine), but measuring the impact of protected area management in freshwater systems may be even more difficult owing to the high level of connectivity and potential for threat propagation within systems (e.g. downstream flow of pollution). We review the potential barriers to conducting impact evaluation for protected area management in freshwater systems. We contrast the barriers identified for freshwater systems to terrestrial systems and discuss potential measurable outcomes and confounders associated with protected area management across the two realms. We identify key research gaps in conducting impact evaluation in freshwater systems that relate to three of their major characteristics: variability, connectivity and time lags in outcomes. Lastly, we use Kakadu National Park world heritage area, the largest national park in Australia, as a case study to illustrate the challenges of measuring impacts of protected area management programmes for environmental outcomes in freshwater systems.

  9. Sediment discharge data for the lower reach of Campbell Creek, Anchorage, Alaska; May to September 1987

    USGS Publications Warehouse

    Lipscomb, S.W.

    1988-01-01

    Streamflow and suspended-sediment data were collected at three sites, two upstream and one downstream from the proposed bridge construction site in Anchorage, Alaska. Immediately downstream from the study reach, the creek enters Campbell Lake, an artificial impoundment in which sedimentation is becoming of concern to recreational users and lakeside residents. (USGS)

  10. Sediment discharge data for the lower reach of Campbell Creek, Anchorage, Alaska; May to October 1986

    USGS Publications Warehouse

    Lipscomb, S.W.

    1987-01-01

    Streamflow and suspended sediment data were collected at two sites in Anchorage, Alaska, one upstream and one downstream from the proposed bridge construction site. Immediately downstream from the study reach, the creek enters Campbell Lake, an artificial impoundment in which sedimentation is becoming of concern to recreational users and lakeside residents. (USGS)

  11. Terrestrial and freshwater Tardigrada of the Americas.

    PubMed

    Meyer, Harry A

    2013-12-16

    This paper provides a comprehensive list of the freshwater and terrestrial tardigrade fauna reported from the Americas (North America, South America, Central America and the West Indies), their distribution in the Americas, and the substrates from which they have been reported. Data were obtained from 316 published references. Authors' identifications were accepted at face value unless subsequently amended. Taxa were assigned to sub-national units (states, provinces, etc.). Many areas, in particular large portions of Central America and the West Indies, have no reported tardigrade fauna.        The presence of 54 genera and 380 species has been reported for the Americas; 245 species have been collected in the Nearctic ecozone and 251 in the Neotropical ecozone. Among the tardigrade species found in the Americas, 52 are currently considered cosmopolitan, while 153 species have known distributions restricted to the Americas. Based on recent taxonomic revision of the genus Milnesium, the vast majority of records of M. tardigradum in the Americas should now be reassigned to Milnesium tardigradum sensu lato, either because the provided description differs from M. tardigradum sensu stricto or because insufficient description is provided to make a determination; the remainder should be considered Milnesium cf. tardigradum.        Most terrestrial tardigrade sampling in the Americas has focused on cryptogams (mosses, lichens and liverworts); 90% of the species have been collected in such substrates. The proportion of species collected in other habitats is lower: 14% in leaf litter, 20% in soil, and 24% in aquatic samples (in other terrestrial substrates the proportion never exceeds 5%). Most freshwater tardigrades have been collected from aquatic vegetation and sediment. For nine species in the Americas no substrates have been reported. 

  12. Terrestrial and freshwater Tardigrada of the Americas.

    PubMed

    Meyer, Harry A

    2013-01-01

    This paper provides a comprehensive list of the freshwater and terrestrial tardigrade fauna reported from the Americas (North America, South America, Central America and the West Indies), their distribution in the Americas, and the substrates from which they have been reported. Data were obtained from 316 published references. Authors' identifications were accepted at face value unless subsequently amended. Taxa were assigned to sub-national units (states, provinces, etc.). Many areas, in particular large portions of Central America and the West Indies, have no reported tardigrade fauna.        The presence of 54 genera and 380 species has been reported for the Americas; 245 species have been collected in the Nearctic ecozone and 251 in the Neotropical ecozone. Among the tardigrade species found in the Americas, 52 are currently considered cosmopolitan, while 153 species have known distributions restricted to the Americas. Based on recent taxonomic revision of the genus Milnesium, the vast majority of records of M. tardigradum in the Americas should now be reassigned to Milnesium tardigradum sensu lato, either because the provided description differs from M. tardigradum sensu stricto or because insufficient description is provided to make a determination; the remainder should be considered Milnesium cf. tardigradum.        Most terrestrial tardigrade sampling in the Americas has focused on cryptogams (mosses, lichens and liverworts); 90% of the species have been collected in such substrates. The proportion of species collected in other habitats is lower: 14% in leaf litter, 20% in soil, and 24% in aquatic samples (in other terrestrial substrates the proportion never exceeds 5%). Most freshwater tardigrades have been collected from aquatic vegetation and sediment. For nine species in the Americas no substrates have been reported.  PMID:25113595

  13. Physical modeling of artificial river replenishment techniques to restore morphological conditions downstream of dams

    NASA Astrophysics Data System (ADS)

    Battisacco, Elena; Franca, Mário J.; Schleiss, Anton J.

    2015-04-01

    The river behavior downstream of dams may be strongly modified in terms of morphology, sediment transport and hydrodynamics. Over the last decades, a reduction on the supply of bed load sediments has been observed in these reaches in several alpine rivers. The main effects resulting from the reduction of sediment supply are bed armoring, river incision and bank instability which can affect negatively the aquatic ecosystem. Artificial river replenishment is one of the proposed technique to mitigate the problem of sediment deficit downstream dams and to restore the sediment continuum along these rivers. Many field experiments were performed in Japan and United States and, more recently, also in Europe. Generally, the full erosion of the replenished volumes was rarely observed and the distance travelled by the sediments in the downstream direction was often not sufficient to reestablish natural morphological conditions. In order to improve the practical applicability of replenishment technique a series of laboratory tests are performed with the purpose to investigate the hydrodynamics of the river flow once artificial replenishment is performed. Erodible volumes, reproducing sediment replenishments, are positioned along the banks of an experimental channel. A 15 m long and 2.5 m flume is used to implement two parallel test channels with trapezoidal cross section with a 0.4 m bed width and 2:3 (V:H) of bank slope. Different geometrical combinations of erodible replenishment, in terms of length, distance between volumes and position along the banks, are tested in the experimental flume. For the replenished volumes colored gravel is used which allows the visual tracking of the temporal evolution of the erosion by means of image analysis. The bed morphology is measured at the beginning and end of the tests by a high definition laser scanner. The influence of discharge is evaluated considering different submergence conditions of the replenishment volumes. The first results

  14. Ecoenzymatic Stoichiometry of Microbial Organic Nutrient Acquisition in Soil and Sediment

    EPA Science Inventory

    Terrestrial soils and freshwater sediments contain reserves of organic carbon estimated at 1500 Pg and 0.2 Pg, respectively. Mineralization of this organic matter by heterotrophic microorganisms drives global carbon and nutrient cycles, controlling plant production and atmospher...

  15. Dramatic inundation changes of China's two largest freshwater lakes linked to the Three Gorges Dam.

    PubMed

    Feng, Lian; Hu, Chuanmin; Chen, Xiaoling; Zhao, Xi

    2013-09-01

    Ever since its planning in the 1990s, the Three Gorges Dam (TGD) caused endless debate in China on its potential impacts on the environment and humans. However, to date, synoptic assessment of environmental changes and their potential linkage with the TGD is still lacking. Here, we combine remote sensing, meteorological, and hydrological observations to investigate the potential influence of the TGD on the downstream freshwater lakes. A 10 year Moderate Resolution Imaging Spectroradiometer (MODIS) time series from 2000 to 2009 revealed significantly decreasing trends (3.3 and 3.6%/year) in the inundation areas of the two largest freshwater lakes of China (Poyang Lake and Dongting Lake) downstream of the TGD since its impoundment in 2003, after which both relative humidity and surface runoff coefficient of the lakes' drainages also dropped dramatically. These environmental changes appear to be linked to the TGD.

  16. Dramatic inundation changes of China's two largest freshwater lakes linked to the Three Gorges Dam.

    PubMed

    Feng, Lian; Hu, Chuanmin; Chen, Xiaoling; Zhao, Xi

    2013-09-01

    Ever since its planning in the 1990s, the Three Gorges Dam (TGD) caused endless debate in China on its potential impacts on the environment and humans. However, to date, synoptic assessment of environmental changes and their potential linkage with the TGD is still lacking. Here, we combine remote sensing, meteorological, and hydrological observations to investigate the potential influence of the TGD on the downstream freshwater lakes. A 10 year Moderate Resolution Imaging Spectroradiometer (MODIS) time series from 2000 to 2009 revealed significantly decreasing trends (3.3 and 3.6%/year) in the inundation areas of the two largest freshwater lakes of China (Poyang Lake and Dongting Lake) downstream of the TGD since its impoundment in 2003, after which both relative humidity and surface runoff coefficient of the lakes' drainages also dropped dramatically. These environmental changes appear to be linked to the TGD. PMID:23919680

  17. 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

  18. Aquatic Sediments.

    ERIC Educational Resources Information Center

    Sanville, W. D.; And Others

    1978-01-01

    Presents a literature review of aquatic sediments and its effect upon water quality, covering publications of 1976-77. This review includes: (1) sediment water interchange; (2) chemical and physical characterization; and (3) heavy water in sediments. A list of 129 references is also presented. (HM)

  19. A Copernicus downstream service for surface displacement monitoring in Germany

    NASA Astrophysics Data System (ADS)

    Cahyadi Kalia, Andre; Frei, Michaela; Lege, Thomas

    2016-04-01

    SAR Interferometry is a powerful technique able to detect and monitor various surface displacements caused by e.g. gravitative mass movement, subrosion, groundwater extraction, fluid injection, natural gas extraction. These processes can e.g. cause damage to buildings, infrastructure, affect ecosystems, agriculture and the economic use of the geological underground by influencing the hydro(geo)logical setting. Advanced techniques of interferometric processing (Persistent Scatterer Interferometry, PSI) allow highly precise displacement measurements (mm precision) by analyzing stacks of SAR imagery. The PSI mapping coverage can be increased to entire nations by using several adjacent satellite tracks. In order to assist the operational use of this technique a German-wide, officially approved, PSI dataset is under development. The intention of this presentation is to show i) the concept of the Copernicus downstream service for surface displacement monitoring in Germany and ii) a pilot study to exemplarily demonstrate the workflow and potential products from the Copernicus downstream service. The pilot study is focusing on the built up of an officially approved wide-area PSI dataset. The study area covers an area of more than 30.000 km² and is located in the Northwest German Basin. Several natural processes (e.g. compaction of marine sediments, peat loss) and anthropogenic activities (e.g. natural gas extraction, rock salt mining) are causing surface displacements in the study area. The PSI analysis is based on six ERS-1/-2 data stacks covering the timespan from 1992 until 2001. Each data stack consists of 49 to 73 ERS-1/-2 SAR images. A comparison of the PSI results with thematic data (e.g. volume and location of extracted natural gas) strongly indicates that a part of the detected land subsidence is caused by natural gas extraction. Furthermore, land subsidence caused by e.g. fluid injection and rock salt mining were successfully detected by the PSI analysis.

  20. A new sampler design for measuring sedimentation in streams

    USGS Publications Warehouse

    Hedrick, Lara B.; Welsh, S.A.; Hedrick, J.D.

    2005-01-01

    Sedimentation alters aquatic habitats and negatively affects fish and invertebrate communities but is difficult to quantify. To monitor bed load sedimentation, we designed a sampler with a 10.16-cm polyvinyl chloride coupling and removable sediment trap. We conducted a trial study of our samplers in riffle and pool habitats upstream and downstream of highway construction on a first-order Appalachian stream. Sediment samples were collected over three 6-week intervals, dried, and separated into five size-classes by means of nested sieves (U.S. standard sieve numbers 4, 8, 14, and 20). Downstream sediment accumulated in size-classes 1 and 2, and the total amount accumulated was significantly greater during all three sampling periods. Size-classes 3 and 4 had significantly greater amounts of sediment for the first two sampling periods at the downstream site. Differences between upstream and downstream sites narrowed during the 5-month sampling period. This probably reflects changes in site conditions, including the addition of more effective sediment control measures after the first 6-week period of the study. The sediment sampler design allowed for long-term placement of traps without continual disturbance of the streambed and was successful at providing repeat measures of sediment at paired sites. ?? Copyright by the American Fisheries Society 2005.

  1. Freshwater diatomite deposits in the western United States

    USGS Publications Warehouse

    Wallace, Alan R.; Frank, David G.; Founie, Alan

    2006-01-01

    Freshwater diatomite deposits in the Western United States are found in lake beds that formed millions of years ago. These diatom-rich sediments are among the Nation's largest commercial diatomite deposits. Each deposit contains billions of tiny diatom skeletons, which are widely used for filtration, absorption, and abrasives. New studies by the U.S. Geological Survey (USGS) are revealing how ancient lakes in the Western States produced such large numbers of diatoms. These findings can be used by both land-use managers and mining companies to better evaluate diatomite resources in the region.

  2. Inhabitants of the Fresh-Water Community.

    ERIC Educational Resources Information Center

    Jorgensen, Joseph; Schroeder, Marlene

    This learner's guide is designed to assist middle school students in studying freshwater organisms. Following a brief introduction to freshwater ecology, simple line drawings facilitate the identification of plants and animals common to Florida's freshwater ecosystems. Emphasis of the short text which accompanies each illustration is upon the…

  3. Methods for preparing synthetic freshwaters.

    PubMed

    Smith, E J; Davison, W; Hamilton-Taylor, J

    2002-03-01

    Synthetic solutions that emulate the major ion compositions of natural waters are useful in experiments aimed at understanding biogeochemical processes. Standard recipes exist for preparing synthetic analogues of seawater, with its relatively constant composition, but, due to the diversity of freshwaters, a range of compositions and recipes is required. Generic protocols are developed for preparing synthetic freshwaters of any desired composition. The major problems encountered in preparing hard and soft waters include dissolving sparingly soluble calcium carbonate, ensuring that the ionic components of each concentrated stock solution cannot form an insoluble salt and dealing with the supersaturation of calcium carbonate in many hard waters. For acidic waters the poor solubility of aluminium salts requires attention. These problems are overcome by preparing concentrated stock solutions according to carefully designed reaction paths that were tested using a combination of experiment and equilibrium modeling. These stock solutions must then be added in a prescribed order to prepare a final solution that is brought into equilibrium with the atmosphere. The example calculations for preparing hard, soft and acidic freshwater surrogates with major ion compositions the same as published analyses, are presented in a generalized fashion that should allow preparation of any synthetic freshwater according to its known analysis. PMID:11902783

  4. Stream sediment sampling and analysis. Final report

    SciTech Connect

    Means, J.L.; Voris, P.V.; Headington, G.L.

    1986-04-01

    The objectives were to sample and analyze sediments from upstream and downstream locations (relative to the Goodyear Atomic plant site) of three streams for selected pollutants. The three streams sampled were the Scioto River, Big Beaver Creek, and Big Run Creek. Sediment samples were analyzed for EPA's 129 priority pollutants (Clean Water Act) as well as isotopic uranium (/sup 234/U, /sup 235/U, and /sup 238/U) and technetium-99.

  5. Estimation of Downstream Cesium Concentrations Following a Postulated PAR Pond Dam Break

    SciTech Connect

    Chen, K.F.

    2002-07-08

    Following a postulated PAR Pond dam break, some of the PAR Pond sediment including the cesium could be eroded and be transported downstream to the Savannah River through the Lower Three Runs Creek. Studies showed that most of the eroded sediment including the cesium would deposit in the Lower Three Runs Creek and the remainder would discharge to the Savannah River from the mouth of Lower Three Runs Creek. A WASP5 model was developed to simulate the eroded sediment and cesium transport from the Lower Three Runs Creek mouth to the Atlantic coast. The dissolved cesium concentrations at the Highway 301 bridge and near the City of Savannah Industrial and Domestic Water Supply Plant are 30 and 27 pCi/l, respectively. The concentrations at both locations are less than the U. S. Environmental Protection Agency drinking water standard of 200 pCi/l.

  6. Rapid reservoir erosion, hyperconcentrated flow, and downstream deposition triggered by breaching of 38 m tall Condit Dam, White Salmon River, Washington

    USGS Publications Warehouse

    Wilcox, Andrew C.; O'Connor, James E.; Major, Jon J.

    2014-01-01

    Condit Dam on the White Salmon River, Washington, a 38 m high dam impounding a large volume (1.8 million m3) of fine-grained sediment (60% sand, 35% silt and clay, and 5% gravel), was rapidly breached in October 2011. This unique dam decommissioning produced dramatic upstream and downstream geomorphic responses in the hours and weeks following breaching. Blasting a 5 m wide hole into the base of the dam resulted in rapid reservoir drawdown, abruptly releasing ~1.6 million m3 of reservoir water, exposing reservoir sediment to erosion, and triggering mass failures of the thickly accumulated reservoir sediment. Within 90 min of breaching, the reservoir's water and ~10% of its sediment had evacuated. At a gauging station 2.3 km downstream, flow increased briefly by 400 m3 s−1during passage of the initial pulse of released reservoir water, followed by a highly concentrated flow phase—up to 32% sediment by volume—as landslide-generated slurries from the reservoir moved downstream. This hyperconcentrated flow, analogous to those following volcanic eruptions or large landslides, draped the downstream river with predominantly fine sand. During the ensuing weeks, suspended-sediment concentration declined and sand and gravel bed load derived from continued reservoir erosion aggraded the channel by >1 m at the gauging station, after which the river incised back to near its initial elevation at this site. Within 15 weeks after breaching, over 1 million m3 of suspended load is estimated to have passed the gauging station, consistent with estimates that >60% of the reservoir's sediment had eroded. This dam removal highlights the influence of interactions among reservoir erosion processes, sediment composition, and style of decommissioning on rate of reservoir erosion and consequent downstream behavior of released sediment.

  7. Rapid reservoir erosion, hyperconcentrated flow, and downstream deposition triggered by breaching of 38 m tall Condit Dam, White Salmon River, Washington

    NASA Astrophysics Data System (ADS)

    Wilcox, Andrew C.; O'Connor, Jim E.; Major, Jon J.

    2014-06-01

    Condit Dam on the White Salmon River, Washington, a 38 m high dam impounding a large volume (1.8 million m3) of fine-grained sediment (60% sand, 35% silt and clay, and 5% gravel), was rapidly breached in October 2011. This unique dam decommissioning produced dramatic upstream and downstream geomorphic responses in the hours and weeks following breaching. Blasting a 5 m wide hole into the base of the dam resulted in rapid reservoir drawdown, abruptly releasing ~1.6 million m3 of reservoir water, exposing reservoir sediment to erosion, and triggering mass failures of the thickly accumulated reservoir sediment. Within 90 min of breaching, the reservoir's water and ~10% of its sediment had evacuated. At a gauging station 2.3 km downstream, flow increased briefly by 400 m3 s-1 during passage of the initial pulse of released reservoir water, followed by a highly concentrated flow phase—up to 32% sediment by volume—as landslide-generated slurries from the reservoir moved downstream. This hyperconcentrated flow, analogous to those following volcanic eruptions or large landslides, draped the downstream river with predominantly fine sand. During the ensuing weeks, suspended-sediment concentration declined and sand and gravel bed load derived from continued reservoir erosion aggraded the channel by >1 m at the gauging station, after which the river incised back to near its initial elevation at this site. Within 15 weeks after breaching, over 1 million m3 of suspended load is estimated to have passed the gauging station, consistent with estimates that >60% of the reservoir's sediment had eroded. This dam removal highlights the influence of interactions among reservoir erosion processes, sediment composition, and style of decommissioning on rate of reservoir erosion and consequent downstream behavior of released sediment.

  8. Turbocharger with downstream pressure-gain combustor

    SciTech Connect

    Sherikar, S.V.

    1991-05-14

    This patent describes a turbocharger. It comprises: an internal combustion engine; a compressor located upstream of the internal combustion engine for increasing the inlet pressure of the internal combustion engine; a turbine located down stream of the internal combustion engine and mechanically coupled to the compressor for driving the compressor; and a pressure-gain combustor located downstream of the turbine for decreasing the outlet pressure of the internal combustion engineer and thus increasing the turbine power output and improving the starting characteristics of the turbocharger.

  9. The impact of silt trapping in large reservoirs on downstream morphology: the Yangtze River

    NASA Astrophysics Data System (ADS)

    van Maren, Dirk Sebastiaan; Yang, Shi-Lun; He, Qing

    2013-06-01

    The sediment load of the Yangtze River (China) is decreasing because of construction of dams, of which the Three Gorges Dam (TGD) is the best known example. The rate of the decline in sediment load is well known, but changes in the sediment grain size distribution have not been given much attention. The TGD mostly traps sand and silt while clay is flushed through the reservoir. A large amount of sand is available in the Yangtze River downstream of the reservoir, and therefore the pre-dam sand concentration is not substantially reduced. The availability of silt on the Yangtze River bed is limited, and it is expected that most silt will be removed from the riverbed within one to two decades. In order to evaluate the impact of the change in grain size distribution on the tidal flats of the Yangtze Estuary, a highly schematized tidal flat model is setup. This model broadly reveals that the observed deposition rates are exceptionally large because of the high sediment concentration, the abundance of silt, the seasonal dominance of waves (shaping a concave profile), and the offshore tidal asymmetry. The model further suggests that deposition rates will be limitedly influenced by reductions in clay or fine silt but strongly impacted by reductions in median to coarse silt. The response of the downstream morphology to reservoir sedimentation therefore strongly depends on the type of trapped sediment. As a consequence, silt-dominated rivers, such as the Yangtze River and the Yellow River may be more strongly impacted than sand-dominated systems.

  10. Influence of Wastewater Discharge on the Metabolic Potential of the Microbial Community in River Sediments.

    PubMed

    Li, Dong; Sharp, Jonathan O; Drewes, Jörg E

    2016-01-01

    To reveal the variation of microbial community functions during water filtration process in river sediments, which has been utilized widely in natural water treatment systems, this study investigates the influence of municipal wastewater discharge to streams on the phylotype and metabolic potential of the microbiome in upstream and particularly various depths of downstream river sediments. Cluster analyses based on both microbial phylogenetic and functional data collectively revealed that shallow upstream sediments grouped with those from deeper subsurface downstream regions. These sediment samples were distinct from those found in shallow downstream sediments. Functional genes associated with carbohydrate, xenobiotic, and certain amino acid metabolisms were overrepresented in upstream and deep downstream samples. In contrast, the more immediate contact with wastewater discharge in shallow downstream samples resulted in an increase in the relative abundance of genes associated with nitrogen, sulfur, purine and pyrimidine metabolisms, as well as restriction-modification systems. More diverse bacterial phyla were associated with upstream and deep downstream sediments, mainly including Actinobacteria, Planctomycetes, and Firmicutes. In contrast, in shallow downstream sediments, genera affiliated with Betaproteobacteria and Gammaproteobacteria were enriched with putative functions that included ammonia and sulfur oxidation, polyphosphate accumulation, and methylotrophic bacteria. Collectively, these results highlight the enhanced capabilities of microbial communities residing in deeper stream sediments for the transformation of water contaminants and thus provide a foundation for better design of natural water treatment systems to further improve the removal of contaminants.

  11. Sediment supply versus local hydraulic controls on sediment transport and storage in a river with large sediment loads

    USGS Publications Warehouse

    Dean, David; Topping, David; Schmidt, John C.; Griffiths, Ronald; Sabol, Thomas

    2016-01-01

    The Rio Grande in the Big Bend region of Texas, USA, and Chihuahua and Coahuila, Mexico, undergoes rapid geomorphic changes as a result of its large sediment supply and variable hydrology; thus, it is a useful natural laboratory to investigate the relative importance of flow strength and sediment supply in controlling alluvial channel change. We analyzed a suite of sediment transport and geomorphic data to determine the cumulative influence of different flood types on changing channel form. In this study, physically based analyses suggest that channel change in the Rio Grande is controlled by both changes in flow strength and sediment supply over different spatial and temporal scales. Channel narrowing is primarily caused by substantial deposition of sediment supplied to the Rio Grande during tributary-sourced flash floods. Tributary floods have large suspended-sediment concentrations, occur for short durations, and attenuate rapidly downstream in the Rio Grande, depositing much of their sediment in downstream reaches. Long-duration floods on the mainstem have the capacity to enlarge the Rio Grande, and these floods, released from upstream dams, can either erode or deposit sediment in the Rio Grande depending upon the antecedent in-channel sediment supply and the magnitude and duration of the flood. Geomorphic and sediment transport analyses show that the locations and rates of sand erosion and deposition during long-duration floods are most strongly controlled by spatial changes in flow strength, largely through changes in channel slope. However, spatial differences in the in-channel sediment supply regulate sediment evacuation or accumulation over time in long reaches (greater than a kilometer).

  12. [Effect of Drought and Subsequent Re-wetting Cycles on Transferable Nitrogen and Its Form Distribution in the Sediment of Water Level Fluctuating Zone in the Tributary of Three Gorge Reservoir Areas].

    PubMed

    Lin, Jun-jie; Zhang, Shuai; Yang, Zhen-yu; He, Li-ping; Zhou, Nong; Zhang, Qian-ru

    2015-07-01

    Nitrogen is the most comment source of eutrophication in freshwater systems. In current study, we investigated the various forms of transferable nitrogen in sediments, which potentially contributed to the nitrogen output into waters. Sediments samples were collected in the water level fluctuating zone of Pengxi River crossing three hydrological sections, e. g. upstream, midstream and downstream and two water level altitudes, 160 m and 170 m, with multiple depths for each site, 0-20, 20-40, 40-60, 60-80, 80-100 cm. To characterize the response of transformation of nitrogen in sediment of the water level fluctuating zone towards cycles of drought and re-wetting processes, we analyzed the content and distribution of transferable nitrogen (TF-N) and its forms. The result showed that the changing of the amount of total nitrogen followed the pattern of upstream > midstream > downstream, the mean value was in the range of 313.02-3 255.53 mg. kg-1, while the content of total transferable nitrogen was on an average of 639.40 mg . kg-1 and coincided with the pattern of total nitrogen. In addition, TF-N followed the pattern of OSF-N > IMOF-N > OSF-N > IEF-N. It indicated that both OSF-N and IMOF-N dominated the form of TF-N in sediments by proportions of 50. 9% and 33. 3%, respectively. Since the transformation rate of OSF-N into dissolved phase was relatively slow, its contribution as a source of nitrogen to eutrophication was limited. We, thus, concluded that IMOF-N was the most important fraction which could be potentially affected by water fluctuation and contributed as dissolved nitrogen into water phase. This study indicated that the manner of manipulating water resource in the Three Gorges Reservoir area has raised the potential risk of transforming IMOF-N from sediment into water phase.

  13. Genotoxicity monitoring of freshwater environments using caged crayfish (Astacus leptodactylus).

    PubMed

    Klobučar, Göran I V; Malev, Olga; Šrut, Maja; Štambuk, Anamaria; Lorenzon, Simonetta; Cvetković, Želimira; Ferrero, Enrico A; Maguire, Ivana

    2012-03-01

    Genotoxicity of freshwater pollution was assessed by measuring DNA damage in haemocytes of caged freshwater crayfish Astacus leptodactylus by the means of Comet assay and micronucleus test, integrated with the measurements of physiological (total protein concentration) and immunological (total haemocyte count) haemolymph parameters as biomarkers of undergone stress. Crayfish were collected at the reference site (River Mrežnica) and exposed in cages for 1 week at three polluted sites along the Sava River (Zagreb, Sisak, Krapje). The long term pollution status of these locations was confirmed by chemical analyses of sediments. Statistically significant increase in DNA damage measured by the Comet assay was observed at all three polluted sites comparing to the crayfish from reference site. In addition, native crayfish from the mildly polluted site (Krapje) cage-exposed on another polluted site (Zagreb) showed lower DNA damage than crayfish from the reference site exposed at the same location indicating adaptation and acclimatisation of crayfish to lower levels of pollution. Micronuclei induction showed similar gradient of DNA damage as Comet assay, but did not reach the statistical significance. Observed increase in total haemocyte count and total protein content in crayfish from polluted environments in the Sava River also confirmed stress caused by exposure to pollution. The results of this study have proved the applicability of caging exposure of freshwater crayfish A. leptodactylus in environmental genotoxicity monitoring using Comet assay and micronucleus test.

  14. Vannellid Species Isolated from Freshwater Source in a Park in Jamaica, West Indies.

    PubMed

    Todd, Cheridah D; Reyes-Batlle, María; Valladares, Basilio; Lindo, John F; Lorenzo-Morales, Jacob

    2015-01-01

    Free-living amoebae (FLA) occupy a wide range of freshwater, marine, and soil habitats, and are opportunistic pathogens in human beings. While Acanthamoeba spp., Naegleria fowleri, and Balamuthia mandrillaris are well-known opportunistic organisms, Vannella epipetala is nonpathogenic. Sediments were collected from a freshwater source from a park in Jamaica to investigate the presence of FLA. Acanthamoeba and Naegleria spp. were not recovered; however, a Vannellid species identified by microscopy and PCR analysis as V. epipetala was isolated. These nonpathogens pose a threat to human beings as they may act as Trojan horses for microsporidian parasites and other pathogens, thereby facilitating their transmission to human beings. PMID:26512204

  15. Vannellid Species Isolated from Freshwater Source in a Park in Jamaica, West Indies

    PubMed Central

    Todd, Cheridah D.; Reyes-Batlle, María; Valladares, Basilio; Lindo, John F.; Lorenzo-Morales, Jacob

    2015-01-01

    Free-living amoebae (FLA) occupy a wide range of freshwater, marine, and soil habitats, and are opportunistic pathogens in human beings. While Acanthamoeba spp., Naegleria fowleri, and Balamuthia mandrillaris are well-known opportunistic organisms, Vannella epipetala is nonpathogenic. Sediments were collected from a freshwater source from a park in Jamaica to investigate the presence of FLA. Acanthamoeba and Naegleria spp. were not recovered; however, a Vannellid species identified by microscopy and PCR analysis as V. epipetala was isolated. These nonpathogens pose a threat to human beings as they may act as Trojan horses for microsporidian parasites and other pathogens, thereby facilitating their transmission to human beings. PMID:26512204

  16. Isotopic Composition of Inorganic Mercury and Methylmercury Downstream of a Historical Gold Mining Region.

    PubMed

    Donovan, Patrick M; Blum, Joel D; Singer, Michael Bliss; Marvin-DiPasquale, Mark; Tsui, Martin T K

    2016-02-16

    We measured total mercury (THg) and monomethyl mercury (MMHg) concentrations and mercury (Hg) isotopic compositions in sediment and aquatic organisms from the Yuba River (California, USA) to identify Hg sources and biogeochemical transformations downstream of a historical gold mining region. Sediment THg concentrations and δ(202)Hg decreased from the upper Yuba Fan to the lower Yuba Fan and the Feather River. These results are consistent with the release of Hg during gold mining followed by downstream mixing and dilution. The Hg isotopic composition of Yuba Fan sediment (δ(202)Hg = -0.38 ± 0.17‰ and Δ(199)Hg = 0.04 ± 0.03‰; mean ± 1 SD, n = 7) provides a fingerprint of inorganic Hg (IHg) that could be methylated locally or after transport downstream. The isotopic composition of MMHg in the Yuba River food web was estimated using biota with a range of %MMHg (the percent of THg present as MMHg) and compared to IHg in sediment, algae, and the food web. The estimated δ(202)Hg of MMHg prior to photodegradation (-1.29 to -1.07‰) was lower than that of IHg and we suggest this is due to mass-dependent fractionation (MDF) of up to -0.9‰ between IHg and MMHg. This result is in contrast to net positive MDF (+0.4 to +0.8‰) previously observed in lakes, estuaries, coastal oceans, and forests. We hypothesize that this unique relationship could be due to differences in the extent or pathway of biotic MMHg degradation in stream environments.

  17. Isotopic composition of inorganic mercury and methylmercury downstream of a historical gold mining region

    USGS Publications Warehouse

    Donovan, Patrick M.; Blum, Joel D.; Singer, Michael B.; Marvin-DiPasquale, Mark C.; Tsui, Martin T.K.

    2016-01-01

    We measured total mercury (THg) and monomethyl mercury (MMHg) concentrations and mercury (Hg) isotopic compositions in sediment and aquatic organisms from the Yuba River (California, USA) to identify Hg sources and biogeochemical transformations downstream of a historical gold mining region. Sediment THg concentrations and δ202Hg decreased from the upper Yuba Fan to the lower Yuba Fan and the Feather River. These results are consistent with the release of Hg during gold mining followed by downstream mixing and dilution. The Hg isotopic composition of Yuba Fan sediment (δ202Hg = −0.38 ± 0.17‰ and Δ199Hg = 0.04 ± 0.03‰; mean ± 1 SD, n = 7) provides a fingerprint of inorganic Hg (IHg) that could be methylated locally or after transport downstream. The isotopic composition of MMHg in the Yuba River food web was estimated using biota with a range of %MMHg (the percent of THg present as MMHg) and compared to IHg in sediment, algae, and the food web. The estimated δ202Hg of MMHg prior to photodegradation (−1.29 to −1.07‰) was lower than that of IHg and we suggest this is due to mass-dependent fractionation (MDF) of up to −0.9‰ between IHg and MMHg. This result is in contrast to net positive MDF (+0.4 to +0.8‰) previously observed in lakes, estuaries, coastal oceans, and forests. We hypothesize that this unique relationship could be due to differences in the extent or pathway of biotic MMHg degradation in stream environments.

  18. Isotopic Composition of Inorganic Mercury and Methylmercury Downstream of a Historical Gold Mining Region.

    PubMed

    Donovan, Patrick M; Blum, Joel D; Singer, Michael Bliss; Marvin-DiPasquale, Mark; Tsui, Martin T K

    2016-02-16

    We measured total mercury (THg) and monomethyl mercury (MMHg) concentrations and mercury (Hg) isotopic compositions in sediment and aquatic organisms from the Yuba River (California, USA) to identify Hg sources and biogeochemical transformations downstream of a historical gold mining region. Sediment THg concentrations and δ(202)Hg decreased from the upper Yuba Fan to the lower Yuba Fan and the Feather River. These results are consistent with the release of Hg during gold mining followed by downstream mixing and dilution. The Hg isotopic composition of Yuba Fan sediment (δ(202)Hg = -0.38 ± 0.17‰ and Δ(199)Hg = 0.04 ± 0.03‰; mean ± 1 SD, n = 7) provides a fingerprint of inorganic Hg (IHg) that could be methylated locally or after transport downstream. The isotopic composition of MMHg in the Yuba River food web was estimated using biota with a range of %MMHg (the percent of THg present as MMHg) and compared to IHg in sediment, algae, and the food web. The estimated δ(202)Hg of MMHg prior to photodegradation (-1.29 to -1.07‰) was lower than that of IHg and we suggest this is due to mass-dependent fractionation (MDF) of up to -0.9‰ between IHg and MMHg. This result is in contrast to net positive MDF (+0.4 to +0.8‰) previously observed in lakes, estuaries, coastal oceans, and forests. We hypothesize that this unique relationship could be due to differences in the extent or pathway of biotic MMHg degradation in stream environments. PMID:26789018

  19. Trait-based modelling of bioaccumulation by freshwater benthic invertebrates.

    PubMed

    Sidney, Livia Alvarenga; Diepens, Noël J; Guo, Xiaoying; Koelmans, Albert A

    2016-07-01

    Understanding the role of species traits in chemical exposure is crucial for bioaccumulation and toxicity assessment of chemicals. We measured and modelled bioaccumulation of polychlorinated biphenyls (PCBs) in Chironomus riparius, Hyalella azteca, Lumbriculus variegatus and Sphaerium corneum. We used a battery test procedure with multiple enclosures in one aquarium, which maximized uniformity of exposure for the different species, such that the remaining variability was due mostly to species traits. The relative importance of uptake from either pore water or sediment ingestion was manipulated by using 28 d aged standard OECD sediment with low (1%) and medium (5%) OM content and 13 months aged sediment with medium OM (5%) content. Survival was ≥76% and wet weight increased for all species. Reproduction of H. azteca and weight gain of H. azteca and S. corneum were significantly higher in the medium OM aged sediments than in other sediments, perhaps due to a more developed microbial community (i.e., increase in food resources). Biota-sediment accumulation factors (BSAF) ranged from 3 to 114, depending on species and PCB congener, with C. riparius (3-10)freshwater taxonomic groups were compared with their marine counterparts and showed overlapping values. The dynamic bioaccumulation model with species-specific bioaccumulation parameters fitted well to the experimental data and showed that bioaccumulation parameters were depended on species traits. Enclosure-based battery tests and mechanistic BSAF models are expected to improve the quality of the exposure assessment in whole sediment toxicity tests. PMID:27126443

  20. Trace elements in freshwater ecosystems in the Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Borg, H.

    2003-05-01

    The expedition Tundra North West 99 visited 17 sites across the Canadian Arctic in order to sample freshwater, sediments, soil and biotic compartments of the ecosystems. Trace metal concentrations were determined using ICP-MS. Dating of sediment profiles using ^137Cs showed a very low sedimentation rate in these lakes (<1 mm/yr). The lake waters were mostly well buffered with high pH