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Sample records for sediment effect concentrations

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

    SciTech Connect

    Carr, R.S.; Biedenbach, J.M.; Long, E.R.; MacDonald, D.D.

    1995-12-31

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

  2. Effect of surfactants at low concentrations on the sorption of atrazine by natural sediment.

    PubMed

    Tao, Qing H; Wang, Dong S; Tang, Hong X

    2006-07-01

    A series of experiments were carried out to determine the effect of surfactants at low concentrations on the sorption of atrazine by natural sediments. With surfactant concentrations ranging from 0 to 20 mg/ L, anionic and cationic surfactants appreciably reduce the adsorption of atrazine, while nonionic surfactant decreases the adsorption of atrazine at concentrations equal to or less than 1 mg/L and increases adsorption at higher concentrations. Desorption of atrazine in the presence of different sodium dodecylbenzene sulfonate (SDBS) concentrations shows that a portion of the bound pesticide resists desorption in the SDBS free system. However, the addition of SDBS accelerates the desorption of atrazine. Furthermore, the nature of sediment and the contacting sequence of SDBS, at 10 mg/L, with the sediment, also influence the adsorption of atrazine. The conclusions in this study could be explained partially by the effect of the type and concentration of surfactants and the characteristics of sediments. PMID:16929634

  3. Light attenuation - a more effective basis for the management of fine suspended sediment than mass concentration?

    PubMed

    Davies-Colley, Robert J; Ballantine, Deborah J; Elliott, Sandy H; Swales, Andrew; Hughes, Andrew O; Gall, Mark P

    2014-01-01

    Fine sediment continues to be a major diffuse pollution concern with its multiple effects on aquatic ecosystems. Mass concentrations (and loads) of fine sediment are usually measured and modelled, apparently with the assumption that environmental effects of sediment are predictable from mass concentrations. However, some severe impacts of fine sediment may not correlate well with mass concentration, notably those related to light attenuation by suspended particles. Light attenuation per unit mass concentration of suspended particulate matter in waters varies widely with particle size, shape and composition. Data for suspended sediment concentration, turbidity and visual clarity (which is inversely proportional to light beam attenuation) from 77 diverse New Zealand rivers provide valuable insights into the mutual relationships of these quantities. Our analysis of these relationships, both across multiple rivers and within individual rivers, supports the proposition that light attenuation by fine sediment is a more generally meaningful basis for environmental management than sediment mass. Furthermore, optical measurements are considerably more practical, being much cheaper (by about four-fold) to measure than mass concentrations, and amenable to continuous measurement. Mass concentration can be estimated with sufficient precision for many purposes from optical surrogates locally calibrated for particular rivers. PMID:24804661

  4. Development and evaluation of consensus-based sediment effect concentrations for polychlorinated biphenyls

    USGS Publications Warehouse

    MacDonald, D.D.; Dipinto, L.M.; Field, J.; Ingersoll, C.G.; Long, E.R.; Swartz, R.C.

    2000-01-01

    Sediment-quality guidelines (SQGs) have been published for polychlorinated biphenyls (PCBs) using both empirical and theoretical approaches. Empirically based guidelines have been developed using the screening-level concentration, effects range, effects level, and apparent effects threshold approaches. Theoretically based guidelines have been developed using the equilibrium-partitioning approach. Empirically-based guidelines were classified into three general categories, in accordance with their original narrative intents, and used to develop three consensus-based sediment effect concentrations (SECs) for total PCBs (tPCBs), including a threshold effect concentration, a midrange effect concentration, and an extreme effect concentration. Consensus-based SECs were derived because they estimate the central tendency of the published SQGs and, thus, reconcile the guidance values that have been derived using various approaches. Initially, consensus-based SECs for tPCBs were developed separately for freshwater sediments and for marine and estuarine sediments. Because the respective SECs were statistically similar, the underlying SQGs were subsequently merged and used to formulate more generally applicable SECs. The three consensus-based SECs were then evaluated for reliability using matching sediment chemistry and toxicity data from field studies, dose-response data from spiked-sediment toxicity tests, and SQGs derived from the equilibrium-partitioning approach. The results of this evaluation demonstrated that the consensus-based SECs can accurately predict both the presence and absence of toxicity in field- collected sediments. Importantly, the incidence of toxicity increases incrementally with increasing concentrations of tPCBs. Moreover, the consensus-based SECs are comparable to the chronic toxicity thresholds that have been estimated from dose-response data and equilibrium-partitioning models. Therefore, consensus-based SECs provide a unifying synthesis of existing

  5. A field investigation of the effect of fine sediment concentration on suspended bed material load

    NASA Astrophysics Data System (ADS)

    Lu, Jau-Yau; Su, Chih-Chiang; Huang, Hsien-Li

    2014-05-01

    The estimation of sediment transport rate has been an important issue for river planning and management. Landslide and debris flow occur frequently in the watershed in Taiwan due to the weak geology and frequent earthquakes. For example, the Chi-Chi Earthquake (Richter scale of 7.3) occurred in central Taiwan in 1999 caused a total landslide area of more than 100 km2. It was the second-deadliest quake in recorded history in Taiwan. In this study, four sets of field experiments (3 typhoons and one large rain storm) were conducted during typhoon seasons of 2012 and 2013 to collect the hydraulic and sediment data at the Tzu-Chiang Bridge of the lower Cho-Shui River after the river incision. The main objectives of this study are to increase our understanding of the variations of the sediment transport characteristics, and to evaluate the suitability of the commonly used sediment transport equations for the lower Cho-Shui River after the Chi-Chi Earthquake. After comparing with the field data collected by Tsang's during 2006-2007, it was found that the concentration of wash load plays an important role in the sediment-laden flow. High concentration of fine sediment tends to damp the turbulence of the flow, and to reduce the uniformities of both the velocity and sediment concentration (bed material load) profiles. In addition, commonly used suspended load sediment transport equations in general under-predicted the sediment load for the lower Cho-Shui River. With consideration of the effect of concentration of fine sediment on the suspended bed material load, Chiu et al.'s (2000) equation was modified and gave more reasonable sediment discharge estimations. Reference Chiu, C. L., Jin, W., and Chen, Y.C., 2000, Mathematical models of distribution of sediment concentration, J. Hydraulic Eng., ASCE, 126(1), 16-23.

  6. A test of sediment effects concentrations: DDT and PCB in the Southern California Bight

    SciTech Connect

    Chapman, P.M.

    1996-07-01

    Full life-cycle (120-d) toxicity tests using the marine polychaete worm Neanthes arenaceodentata were conducted on Southern California Bight sediments contaminated with PCBs and DDTs. Independent efforts to determine concentrations of polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethanes (DDTs) along the Southern California Bight which result in adverse biological effects resulted in similar values. A correlative approach using historic data calculated the following likely sediment effects concentrations: total DDTs, 7.12 mg/dry kg (199 mg/kg organic carbon [OC]); and total PCBs, 0.592 mg/dry kg (30.4 mg/kg OC). Testing of field-collected sediments yielded the following no-observed-effect concentrations based on full life-cycle testing: total DDTs, 8.51 mg/dry kg (269 mg/kg OC); and total PCBs, 1.07 mg/dry kg (36.6 mg/kg OC).

  7. Incidence of adverse biological effects within ranges of chemical concentrations in marine and estuarine sediments

    NASA Astrophysics Data System (ADS)

    Long, Edward R.; MacDonald, Donald D.; Smith, Sherri L.; Calder, Fred D.

    1995-01-01

    Matching biological and chemical data were compiled from numerous modeling, laboratory, and field studies performed in marine and estuarine sediments. Using these data, two guideline values (an effects range-low and an effects range-median) were determined for nine trace metals, total PCBs, two pesticides, 13 polynuclear aromatic hydrocarbons (PAHs), and three classes of PAHs. The two values defined concentration ranges that were: (1) rarely, (2) occasionally, or (3) frequently associated with adverse effects. The values generally agreed within a factor of 3 or less with those developed with the same methods applied to other data and to those developed with other effects-based methods. The incidence of adverse effects was quantified within each of the three concentration ranges as the number of cases in which effects were observed divided by the total number of observations. The incidence of effects increased markedly with increasing concentrations of all of the individual PAHs, the three classes of PAHs, and most of the trace metals. Relatively poor relationships were observed between the incidence of effects and the concentrations of mercury, nickel, total PCB, total DDT and p,p'-DDE. Based upon this evaluation, the approach provided reliable guidelines for use in sediment quality assessments. This method is being used as a basis for developing National sediment quality guidelines for Canada and informal, sediment quality guidelines for Florida.

  8. Hysteresis effects in suspended sediment concentration of an allogenic river channel in a very arid environment

    NASA Astrophysics Data System (ADS)

    Yu, Guo-An; Disse, Markus; Yu, Yang

    2016-04-01

    Suspended sediment dynamics of the Tarim River, an allogenic and perennial river flowing in a very arid environment in China, are analyzed to examine the hysteresis effects based on data of flow discharge (Q) and suspended sediment concentration (SSC) from two hydrologic gauging stations in the river in the last five decades (1960-2011). Strong hysteresis effects existed in the sediment rating curves of the Tarim River. Under similar flow conditions, the first flood event in a year quite often causes higher suspended sediment concentration (SSC value), and form a rating curve visibly different from later flood processes. The successive flood events often form rating curves gradually from left to right progressively with time on the SSC-Q plot, indicating that higher flow intensity is needed for later flood events to reach the same SSC value of the earlier flood events. Three hysteresis loop forms, i.e., clockwise, anti-clockwise and Figure-eight existed with occurrence frequency of 57%, 27.3% and 15.6% respectively, showing that clockwise loop is the major hysteresis form and sediment load is generally derived from the channel bed. The very weak banks due to composition of quite homogeneous noncohesive particles (fine sand, silt and almost no clay content) often induce bank failure, which complicates suspended sediment dynamics and causes to shape different hysteresis loops. Somehow random but occurrence of bank collapse with higher possibility near the peak and at the falling limb of a flood hydrograph is probably the major reason causing anti-clockwise and figure-eight hysteresis loops.

  9. Effects of suspended sediment concentration and grain size on three optical turbidity sensors

    USGS Publications Warehouse

    Merten, Gustavo Henrique; Capel, Paul D.; Minella, Jean P.G.

    2014-01-01

    Purpose: Optical turbidity sensors have been successfully used to determine suspended sediment flux in rivers, assuming the relation between the turbidity signal and suspended sediment concentration (SSC) has been appropriately calibrated. Sediment size, shape and colour affect turbidity and are important to incorporate into the calibration process. Materials and methods: This study evaluates the effect of SSC and particle size (i.e. medium sand, fine sand, very fine sand, and fines (silt + clay)) on the sensitivity of the turbidity signal. Three different turbidity sensors were used, with photo detectors positioned at 90 and 180 degrees relative to the axis of incident light. Five different sediment ratios of sand:fines (0:100, 25:75, 50:50, 75:25 and 100:0) were also evaluated for a single SSC (1000 mg l-1). Results and discussion: The photo detectors positioned at 90 degrees were more sensitive than sensor positioned at 180 degrees in reading a wide variety of grain size particles. On average for the three turbidity sensors, the sensitivity for fines were 170, 40, and 4 times greater than sensitivities for medium sand, fine sand, and very fine sand, respectively. For an SSC of 1000 mg l-1 with the treatments composed of different proportions of sand and fines, the presence of sand in the mixture linearly reduced the turbidity signal. Conclusions: The results indicate that calibration of the turbidity signal should be carried out in situ and that the attenuation of the turbidity signal due to sand can be corrected, as long as the proportion of sand in the SSC can be estimated.

  10. Degradation of fipronil in anaerobic sediments and the effect on porewater concentrations.

    PubMed

    Brennan, Amanda A; Harwood, Amanda D; You, Jing; Landrum, Peter F; Lydy, Michael J

    2009-09-01

    The current study measured the degradation of fipronil in laboratory-spiked silt loam sediment under anaerobic conditions at different aging times. The half-life of fipronil in anaerobic sediments spiked at 5.8+/-0.049 and 21+/-1.4microg/kg dry weight (dw) was 21+/-0.22 and 15+/-0.11d, respectively. Fipronil-sulfide was the primary degradation product with fipronil-sulfone detected at lower concentrations. No degradation occurred to fipronil-sulfide and fipronil-sulfone over 200d in separate systems. A concurrent decline in sediment concentrations resulted in a decline of fipronil in sediment porewater with an increase in fipronil-sulfide and fipronil-sulfone measured by matrix-solid phase microextraction (matrix-SPME). Equilibrium among sediment, porewater, and matrix-SPME fiber occurred within 138d for fipronil and fipronil-sulfone; however, fipronil-sulfide did not reach equilibrium during the test, and modeling predicted upwards of 1083d to reach equilibrium. Regardless of the time to reach equilibrium, the rapid degradation of fipronil has little ecological significance given that fipronil-sulfide and fipronil-sulfone have equal or greater toxicity, and exhibit greater environmental stability in both the sediment and porewater, thereby becoming bioavailable. PMID:19576615

  11. Secondary grain-size effects on Li and Cs concentrations and appropriate normalization procedures for coastal sediments

    NASA Astrophysics Data System (ADS)

    Jung, Hoisoo; Lim, Dhongil; Xu, Zhaokai; Jeong, Kapsik

    2016-06-01

    The sediment grain-size effect (GSE), a fundamental factor relevant to the interpretation of elemental concentrations and isotopic compositions, has been normalized using conservative elements such as aluminum (Al), cesium (Cs), and lithium (Li) (C(Al,Cs,Li)), which serve as proxies for the natural metal-controlling variables of grain size, mineralogy, and organic matter. However, a secondary GSE reportedly remains even after compensation by the Al-normalization procedure, particularly for the concentrations of transition metals (CT.M). This secondary effect also occurred in the C(Li,Cs)/CAl ratios of the Korean coastal sediments examined in this study. The primary and secondary GSEs on Cs and Li concentrations can be explained by the quartz-dilution effect and the Cs- and Li-incorporation effect of phyllosilicate minerals, respectively, based on a model involving three component end-members: a Cs- and Li-free sand-dominated sediment component consisting mostly of quartz and feldspar, a Cs- and Li-bearing silt-dominated component of mica, and a Cs- and Li-enriched clay-dominated component of illite. Although the primary and secondary GSEs on the concentrations of transition metals (particularly Cu and Ni) in coastal sediments might be normalized by dividing the metal concentrations by the square of the Al concentration (CT.M./(CAl)2), the GSEs can also be normalized by dividing the concentrations by the exact Cs (or Li) concentration (CT.M./CCs).

  12. Effect of sampling method on measured concentrations of sulfide and ammonia in sediment toxicity tests

    SciTech Connect

    Phillips, B.M.; Anderson, B.S.; Hunt, J.W.

    1994-12-31

    Sulfide and ammonia are natural components of marine sediments which may occur in concentrations toxic to marine organisms. Because these compounds are toxic, it is important to measure them accurately to determine their influence on toxicity test results. Standard solid phase test protocols may not adequately address sampling methodology for ammonia and sulfide analysis. Samples are commonly taken from overlying water in test containers, which may not adequately characterize the medium to which test animals are exposed. As part of research conducted under the California State Water Resources Control Board`s Bay Protection and Toxic Cleanup Program, the authors are investigating alternative sampling methods to more accurately characterize sulfide and ammonia in sediments. Measurements taken from water overlying test sediment are compared to those taken from interstitial water in tests using Neanthes and Rhepoxynius. Pre-test interstitial samples are extracted from sediment using centrifugation. Final measurements are made on water centrifuged from sediment in an additional laboratory replicate. Oxidation can affect the measurement of both constituents, therefore efforts are made to reduce oxidation by centrifuging with no head space. Ammonia is analyzed immediately using an ion specific electrode, and sulfide samples are preserved for spectrophotometric analysis. In preliminary studies sulfide concentrations were 13 times higher and ammonia concentrations 4 times higher in the interstitial water than in samples taken from overlying water. Results will be discussed in terms of sulfide and ammonia toxicity and possible ways of improving sampling methodology.

  13. Effect of oxalic acid treatment on sediment arsenic concentrations and lability under reducing conditions.

    PubMed

    Sun, Jing; Bostick, Benjamin C; Mailloux, Brian J; Ross, James M; Chillrud, Steven N

    2016-07-01

    Oxalic acid enhances arsenic (As) mobilization by dissolving As host minerals and competing for sorption sites. Oxalic acid amendments thus could potentially improve the efficiency of widely used pump-and-treat (P&T) remediation. This study investigates the effectiveness of oxalic acid on As mobilization from contaminated sediments with different As input sources and redox conditions, and examines whether residual sediment As after oxalic acid treatment can still be reductively mobilized. Batch extraction, column, and microcosm experiments were performed in the laboratory using sediments from the Dover Municipal Landfill and the Vineland Chemical Company Superfund sites. Oxalic acid mobilized As from both Dover and Vineland sediments, although the efficiency rates were different. The residual As in both Dover and Vineland sediments after oxalic acid treatment was less vulnerable to microbial reduction than before the treatment. Oxalic acid could thus improve the efficiency of P&T. X-ray absorption spectroscopy analysis indicated that the Vineland sediment samples still contained reactive Fe(III) minerals after oxalic acid treatment, and thus released more As into solution under reducing conditions than the treated Dover samples. Therefore, the efficacy of enhanced P&T must consider sediment Fe mineralogy when evaluating its overall potential for remediating groundwater As. PMID:26970042

  14. Effects of salinity and particle concentration on sediment hydrodynamics and critical bed-shear-stress for erosion of fine grained sediments used in wetland restoration projects

    NASA Astrophysics Data System (ADS)

    Ghose-Hajra, M.; McCorquodale, A.; Mattson, G.; Jerolleman, D.; Filostrat, J.

    2015-03-01

    Sea-level rise, the increasing number and intensity of storms, oil and groundwater extraction, and coastal land subsidence are putting people and property at risk along Louisiana's coast, with major implications for human safety and economic health of coastal areas. A major goal towards re-establishing a healthy and sustainable coastal ecosystem has been to rebuild Louisiana's disappearing wetlands with fine grained sediments that are dredged or diverted from nearby rivers, channels and lakes to build land in open water areas. A thorough geo-hydrodynamic characterization of the deposited sediments is important in the correct design and a more realistic outcome assessment of the long-term performance measures for ongoing coastal restoration projects. This paper evaluates the effects of salinity and solid particle concentration on the re-suspension characteristics of fine-grained dredged sediments obtained from multiple geographic locations along the Gulf coast. The critical bed-shear-stress for erosion has been evaluated as a function of sedimentation time. The sediment hydrodynamic properties obtained from the laboratory testing were used in a numerical coastal sediment distribution model to aid in evaluating sediment diversions from the Mississippi River into Breton Sound and Barataria Bay.

  15. 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. PMID:26638155

  16. Effect of river landscape on the sediment concentrations of antibiotics and corresponding antibiotic resistance genes (ARG).

    PubMed

    Pei, Ruoting; Kim, Sung-Chul; Carlson, Kenneth H; Pruden, Amy

    2006-07-01

    The purpose of this study was to quantify antibiotic resistance genes (ARG) in the sediments of the mixed-landscape Cache La Poudre River, which has previously been studied and shown to have high concentrations of antibiotics related to urban and agricultural activities. River sediments were sampled during two events (high-flow and low-flow) from five sites with varying urban and agricultural impact levels. Polymerase-chain-reaction (PCR) detection assays were conducted for four sulfonamide resistance gene families, using newly designed primers, and five tetracycline resistance gene families, using previously published primers. Sul(I), sul(II), tet(W), and tet(O) gene families were further quantified by real-time quantitative polymerase chain reaction (Q-PCR). Resistance to four classes of antibiotics (tetracyclines, sulfonamides, ionophores, and macrolides) was also investigated using a culture-based approach. The quantities of resistance genes normalized to the 16S gene copy number were significantly different between the sites, with higher resistance gene concentrations at the impacted sites than at the pristine site. Total resistant CFUs were over an order of magnitude lower at the pristine site, but differences were less apparent when normalized to the total CFUs. Six tetracyclines and six sulfonamides were also quantified in the sediments and were found to be highest at sites impacted by urban and agricultural activity, with no antibiotics detected at the pristine sit. To the knowledge of the authors, this study is the first to demonstrate a relationship between urban and agricultural activity and microbial resistance in river sediments using quantitative molecular tools. PMID:16753197

  17. Effect of arsenic concentration on microbial iron reduction and arsenic speciation in an iron-rich freshwater sediment

    NASA Astrophysics Data System (ADS)

    Chow, Stephanie S.; Taillefert, Martial

    2009-10-01

    Depth profiles in the sediment porewaters of the Chattahoochee River (Georgia, USA) show that iron oxides scavenge arsenate in the water column and settle to the sediment-water interface (SWI) where they are reduced by iron-reducing bacteria. During their reduction, these particles seem to release arsenic to the porewaters in the form of arsenate only. Sediment slurry incubations were conducted to determine the effect of low concentrations of arsenic (⩽10 μM) on biogeochemical processes in these sediments. Experiments confirm that any arsenate (As(V)) added to these sediments is immediately adsorbed in oxic conditions and released in anoxic conditions during the microbial reduction of authigenic iron oxides. Incubations in the presence of ⩽1 μM As(V) reveal that arsenate is released but not concomitantly reduced during this process. Simultaneously, microbial iron reduction is enhanced significantly, spurring the simultaneous release of arsenate into porewaters and secondary formation of crystalline iron oxides. Above 1 μM As(V), however, the microbial reductive dissolution of iron oxides appears inhibited by arsenate, and arsenite is produced in excess in the porewaters. These incubations show that even low inputs of arsenic to riverine sediments may affect microbial processes, the stability of iron oxides and, indirectly, the cycling of arsenic. Possible mechanisms for such effects on iron reduction are proposed.

  18. Equilibrium Partitioning Approach for Assessing Toxicity of Contaminants in Sediments: Linking Measured Concentrations to Effects

    EPA Science Inventory

    A variety of approaches exist for assessing the degree, extent and/or risk of metals contamination in sediments. Selection of the “correct” approach depends on the nature of the question being asked (e.g., the degree of metals contamination in marine sediments may be estimated by...

  19. Comparison of the basin-scale effect of dredging operations and natural estuarine processes on suspended sediment concentration

    USGS Publications Warehouse

    Schoellhamer, D.H.

    2002-01-01

    Suspended sediment concentration (SSC) data from San Pablo Bay, California, were analyzed to compare the basin-scale effect of dredging and disposal of dredged material (dredging operations) and natural estuarine processes. The analysis used twelve 3-wk to 5-wk periods of mid-depth and near-bottom SSC data collected at Point San Pablo every 15 min from 1993-1998. Point San Pablo is within a tidal excursion of a dredged-material disposal site. The SSC data were compared to dredging volume, Julian day, and hydrodynamic and meteorological variables that could affect SSC. Kendall's ??, Spearman's ??, and weighted (by the fraction of valid data in each period) Spearman's ??w correlation coefficients of the variables indicated which variables were significantly correlated with SSC. Wind-wave resuspension had the greatest effect on SSC. Median water-surface elevation was the primary factor affecting mid-depth SSC. Greater depths inhibit wind-wave resuspension of bottom sediment and indicate greater influence of less turbid water from down estuary. Seasonal variability in the supply of erodible sediment is the primary factor affecting near-bottom SSC. Natural physical processes in San Pablo Bay are more areally extensive, of equal or longer duration, and as frequent as dredging operations (when occurring), and they affect SSC at the tidal time scale. Natural processes control SSC at Point San Pablo even when dredging operations are occurring.

  20. The effects of sediment depth and oxygen concentration on the use of organic matter: An experimental study using an infiltration sediment tank.

    PubMed

    Freixa, A; Rubol, S; Carles-Brangarí, A; Fernàndez-Garcia, D; Butturini, A; Sanchez-Vila, X; Romaní, A M

    2016-01-01

    Water flowing through hyporheic river sediments or artificial recharge facilities promotes the development of microbial communities with sediment depth. We performed an 83-day mesocosm infiltration experiment, to study how microbial functions (e.g., extracellular enzyme activities and carbon substrate utilization) are affected by sediment depth (up to 50 cm) and different oxygen concentrations. Results indicated that surface sediment layers were mainly colonized by microorganisms capable of using a wide range of substrates (although they preferred to degrade carbon polymeric compounds, as indicated by the higher β-glucosidase activity). In contrast, at a depth of 50 cm, the microbial community became specialized in using fewer carbon substrates, showing decreased functional richness and diversity. At this depth, microorganisms picked nitrogenous compounds, including amino acids and carboxyl acids. After the 83-day experiment, the sediment at the bottom of the tank became anoxic, inhibiting phosphatase activity. Coexistence of aerobic and anaerobic communities, promoted by greater physicochemical heterogeneity, was also observed in deeper sediments. The presence of specific metabolic fingerprints under oxic and anoxic conditions indicated that the microbial community was adapted to use organic matter under different oxygen conditions. Overall the heterogeneity of oxygen concentrations with depth and in time would influence organic matter metabolism in the sediment tank. PMID:25900223

  1. EFFECTS OF SUSPENDED SEDIMENT ON CHLOROPHYLL CONCENTRATION AND IMPLICATIONS FOR TMDL CRITERIA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Traditional agricultural practices often result in soil erosion that can lead to increased turbidity in oxbow lakes and subsequent reduced productivity. Suspended sediment has been identified as a primary cause of low productivity due to its interference with photosynthesis in phytoplankton. Conse...

  2. Uranium Adsorption to A Hanford Sediment Sample: Effects of Suspended Particle Concentration at High pH

    NASA Astrophysics Data System (ADS)

    Bai, J.; Ball, W. P.

    2006-05-01

    Adsorption (surface complexation) is an important retardation process involved in the transport of uranium(VI) in the subsurface environment at the Hanford, WA DOE site. Accurate evaluation of adsorption equilibrium by means of adsorption isotherm experiments is a prerequisite for understanding and modeling uranium(VI) transport and fate. In this study, several series of batch adsorption experiments were performed at controlled pH (8.0, 8.5 and 9.5) on replicate samples of a silt/clay-size fraction of sediment culled from core borings located roughly 43 meters below the SX Tank farm at the Hanford site. At pH 8.0 and 8.5, the adsorption isotherm was found to be reversible and independent of the concentration of suspended sediment particles, and to be well described by a Freundlich model. At pH 9.5, however, the observed adsorption was found to depend on the experimental conditions of particle concentration - 100g/L, 200g/L and 400g/L were tested. Stronger adsorption was observed for lower particle concentrations, and desorption was less complete under these conditions. Various hypotheses, including colloidal effects, solid aggregation, and surface precipitation, are being explored as explanation of these observations. Centrifugation and ultra-filtration results suggest that colloidal effects are unlikely, and flow-through columns are currently being conducted (with re-circulated stock uranium solution) to investigate whether physical phenomena (e.g. effects of particle-particle contact) are a possible cause. It is also possible that surface precipitation may be occurring under some conditions, and on- going investigations will explore this possibility.

  3. Bioleaching of heavy metals from contaminated sediment by indigenous sulfur-oxidizing bacteria in an air-lift bioreactor: effects of sulfur concentration.

    PubMed

    Chen, Shen-Yi; Lin, Jih-Gaw

    2004-01-01

    The effects of sulfur concentration on the bioleaching of heavy metals from the sediment by indigenous sulfur-oxidizing bacteria were investigated in an air-lift reactor. Increasing the sulfur concentration from 0.5 to 5 g/l enhanced the rates of pH reduction, sulfate production and metal solubilization. A Michaelis-Menten type equation was used to explain the relationships between sulfur concentration, sulfate production and metal solubilization in the bioleaching process. After 8 days of bioleaching, 97-99% of Cu, 96-98% of Zn, 62-68% of Mn, 73-87% of Ni and 31-50% of Pb were solubilized from the sediment, respectively. The efficiency of metal solubilization was found to be related to the speciation of metal in the sediment. From economical consideration, the recommended sulfur dosage for the bioleaching of metals from the sediment is 3g/l. PMID:15276736

  4. g Dependent particle concentration due to sedimentation

    NASA Astrophysics Data System (ADS)

    Haranas, Ioannis; Gkigkitzis, Ioannis; Zouganelis, George D.

    2012-11-01

    Sedimentation of particles in a fluid has long been used to characterize particle size distribution. Stokes' law is used to determine an unknown distribution of spherical particle sizes by measuring the time required for the particles to settle a known distance in a fluid of known viscosity and density. In this paper, we study the effects of gravity on sedimentation by examining the resulting particle concentration distributed in an equilibrium profile of concentration C m, n above the bottom of a container. This is for an experiment on the surface of the Earth and therefore the acceleration of gravity had been corrected for the oblateness of the Earth and its rotation. Next, at the orbital altitude of the spacecraft in orbit around Earth the acceleration due to the central field is corrected for the oblateness of the Earth. Our results show that for experiments taking place in circular or elliptical orbits of various inclinations around the Earth the concentration ratio C m, n / C m, ave , the inclination seems to be the most ineffective in affecting the concentration among all the orbital elements. For orbital experiment that use particles of diameter d p =0.001 μm the concentration ratios for circular and slightly elliptical orbits in the range e=0-0.1 exhibit a 0.009 % difference. The concentration ratio increases with the increase of eccentricity, which increases more for particles of larger diameters. Finally, for particles of the same diameter concentration ratios between Earth and Mars surface experiments are related in the following way C_{(m,n)_{mathit{Earth}}} = 0.99962 C_{(m,n)_{mathit{Mars}}}.

  5. San Francisco Bay Sediment Concentration

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This March 3, 2000 image of the San Francisco Bay region shows a 60 by 75 kilometer Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image in band 1 (near infrared, 0.52-0.60 microns). The color coded suspended sediment image was created from band 1 by blacking out the land, and assigning colors to the relative brightnesses in the water. High values were colored white, then red, yellow, green, and blue. Brighter values in band 1 indicate higher sediment load in the water. The highest values are in Suisun and San Pablo Bays, into which the Sacramento River empties, and along the coast of the San Francisco Peninsula. The Pacific Ocean and San Francisco Bay water are relatively clear. Image courtesy ASTER Science Team

  6. Effects of increasing temperatures on methane concentrations and methanogenesis during experimental incubation of sediments from oligotrophic and mesotrophic lakes

    NASA Astrophysics Data System (ADS)

    Fuchs, Andrea; Lyautey, Emilie; Montuelle, Bernard; Casper, Peter

    2016-05-01

    Global warming is expected to raise temperatures in freshwater lakes, which have been acknowledged to contribute up to 10% of the atmospheric methane concentrations. Increasing temperature enhances methane production and oxidation rates, but few studies have considered the balance between both processes at experimentally higher temperatures within lake sediments. The temperature dependence of methane concentrations, methane production rates, and methanogenic (mcrA) and methanotrophic (pmoA) community size was investigated in intact sediment cores incubated with aerobic hypolimnion water at 4, 8, and 12°C over 3 weeks. Sediment cores of 25 cm length were collected at two temperate lakes—Lake Stechlin (Germany; mesotrophic-oligotrophic, maximum depth 69.5 m) and Lake Geneva (France/Switzerland; mesotrophic, maximum depth 310 m). While methane production rates in Lake Stechlin sediments did not change with increasing temperatures, methane concentrations decreased significantly. In contrast, methane production rates increased in 20-25 cm in Lake Geneva sediments with increasing temperatures, but methane concentrations did not differ. Real-time PCR demonstrated the methanogenic and methanotrophic community size remained stable independently of the incubation temperature. Methane concentrations as well as community sizes were 1-2 orders of magnitude higher in Lake Stechlin than in Lake Geneva, while potential methane production rates after 24 h were similar in both lakes, with on average 2.5 and 1.9 nmol g-1 DW h-1, respectively. Our results suggest that at higher temperatures methane oxidation could balance, and even exceed, methane production. This suggests that anaerobic methane oxidation could be involved in the methane balance at a more important rate than previously anticipated.

  7. A data reconnaissance on the effect of suspended-sediment concentrations on dissolved-solids concentrations in rivers and tributaries in the Upper Colorado River Basin

    NASA Astrophysics Data System (ADS)

    Tillman, Fred D.; Anning, David W.

    2014-11-01

    The Colorado River is one of the most important sources of water in the western United States, supplying water to over 35 million people in the U.S. and 3 million people in Mexico. High dissolved-solids loading to the River and tributaries are derived primarily from geologic material deposited in inland seas in the mid-to-late Cretaceous Period, but this loading may be increased by human activities. High dissolved solids in the River causes substantial damages to users, primarily in reduced agricultural crop yields and corrosion. The Colorado River Basin Salinity Control Program was created to manage dissolved-solids loading to the River and has focused primarily on reducing irrigation-related loading from agricultural areas. This work presents a reconnaissance of existing data from sites in the Upper Colorado River Basin (UCRB) in order to highlight areas where suspended-sediment control measures may be useful in reducing dissolved-solids concentrations. Multiple linear regression was used on data from 164 sites in the UCRB to develop dissolved-solids models that include combinations of explanatory variables of suspended sediment, flow, and time. Results from the partial t-test, overall likelihood ratio, and partial likelihood ratio on the models were used to group the sites into categories of strong, moderate, weak, and no-evidence of a relation between suspended-sediment and dissolved-solids concentrations. Results show 68 sites have strong or moderate evidence of a relation, with drainage areas for many of these sites composed of a large percentage of clastic sedimentary rocks. These results could assist water managers in the region in directing field-scale evaluation of suspended-sediment control measures to reduce UCRB dissolved-solids loading.

  8. A data reconnaissance on the effect of suspended-sediment concentrations on dissolved-solids concentrations in rivers and tributaries in the Upper Colorado River Basin

    USGS Publications Warehouse

    Tillman, Fred D; Anning, David W.

    2014-01-01

    The Colorado River is one of the most important sources of water in the western United States, supplying water to over 35 million people in the U.S. and 3 million people in Mexico. High dissolved-solids loading to the River and tributaries are derived primarily from geologic material deposited in inland seas in the mid-to-late Cretaceous Period, but this loading may be increased by human activities. High dissolved solids in the River causes substantial damages to users, primarily in reduced agricultural crop yields and corrosion. The Colorado River Basin Salinity Control Program was created to manage dissolved-solids loading to the River and has focused primarily on reducing irrigation-related loading from agricultural areas. This work presents a reconnaissance of existing data from sites in the Upper Colorado River Basin (UCRB) in order to highlight areas where suspended-sediment control measures may be useful in reducing dissolved-solids concentrations. Multiple linear regression was used on data from 164 sites in the UCRB to develop dissolved-solids models that include combinations of explanatory variables of suspended sediment, flow, and time. Results from the partial t-test, overall likelihood ratio, and partial likelihood ratio on the models were used to group the sites into categories of strong, moderate, weak, and no-evidence of a relation between suspended-sediment and dissolved-solids concentrations. Results show 68 sites have strong or moderate evidence of a relation, with drainage areas for many of these sites composed of a large percentage of clastic sedimentary rocks. These results could assist water managers in the region in directing field-scale evaluation of suspended-sediment control measures to reduce UCRB dissolved-solids loading.

  9. Effects of polychlorinated biphenyl congener concentration and sediment supplementation on rates of methanogenesis and 2,3,6-trichlorobiphenyl dechlorination in an anaerobic enrichment

    SciTech Connect

    Boyle, A.W.; May, H.D. ); Blake, C.K. ); Price, W.A. )

    1993-09-01

    The release of polychlorinated biphenyls (PCBs) into the environment has caused public concern. PCBs are know known to be susceptible to biodegradation; PCBs in the Hudson river have been shown to be extensively dechlorinated, but the rate of dechlorination in anaerobic environments have been slow, over months or years. This study tested the effects of PCB concentration and sediment supplementation with 2,3,6-trichlorobiphenol, on the rate of PCB dechlorination and methanogenesis. The rates of meta dechlorination in sediment supplemented cultures were measured in the laboratory, including both the rate per bacterial cell and the rate of methanogenesis when dechlorination increases. 24 refs., 3 figs., 1 tab.

  10. Effects of cultivation and reforestation on suspended sediment concentrations: a case study in a mountainous catchment in China

    NASA Astrophysics Data System (ADS)

    Fang, N. F.; Chen, F. X.; Zhang, H. Y.; Wang, Y. X.; Shi, Z. H.

    2015-08-01

    Understanding how sediment concentrations vary with land use/cover is critical for evaluating the current and future impacts of human activities on river systems. This paper presents suspended sediment concentration (SSC) dynamics and the relationship between SSC and discharge (Q) in the 8973 km2 Du catchment and its sub-catchment (4635 km2). In the Du catchment and its sub-catchment, 4235 and 3980 paired Q-SSC samples, respectively, were collected over 30 years. Under the influence of the "Household Contract Responsibility System" and Grain-for-Green projects in China, three periods were designated, the original period (1980s), cultivation period (1990s), and reforestation period (2000s). The results of a Mann-Kendall test showed that rainfall slightly increased during the study years; however, the annual discharge and sediment load significantly decreased. The annual suspended sediment yield of the Du catchment varied between 4 and 332 kg s-1, and that of the sub-catchment varied between 2 and 135 kg s-1. The SSCs in the catchment and sub-catchment fluctuated between 1 and 22 400 g m-3 and between 1 and 31 800 g m-3, respectively. The mean SSC of the Du catchment was relatively stable during the three periods (±83 g m-3). ANOVA indicated that the SSC did not significantly change under cultivation for low and moderate flows, but was significantly different under high flow during reforestation of the Du catchment. The SSC in the sub-catchment was more variable, and the mean-SSC in the sub-catchment varied from 1058 g m-3 in the 1980s to 1256 g m-3 in the 1990s and 891 g m-3 in the 2000s. Reforestation significantly decreased the SSCs during low and moderate flows, whereas cultivation increased the SSCs during high flow. The sediment rating curves showed a stable relationship between the SSC and Q in the Du catchment during the three periods. However, the SSC-Q of the sub-catchment exhibited scattered relationships during the original and cultivation periods and a

  11. Effects of cultivation and reforestation on suspended sediment concentrations: a case study in a mountainous catchment in China

    NASA Astrophysics Data System (ADS)

    Fang, N. F.; Chen, F. X.; Zhang, H. Y.; Wang, Y. X.; Shi, Z. H.

    2016-01-01

    Understanding how sediment concentrations vary with land use/cover is critical for evaluating the current and future impacts of human activities on river systems. This paper presents suspended sediment concentration (SSC) dynamics and the relationship between SSC and discharge (Q) in the 8973 km2 Du catchment and its sub-catchment (4635 km2). In the Du catchment and its sub-catchment, 4235 and 3980 paired SSC-Q samples, respectively, were collected over 30 years. Under the influence of the Household Contract Responsibility System and Grain-for-Green projects in China, three periods were designated, the original period (1980s), cultivation period (1990s) and reforestation period (2000s). The results of a Mann-Kendall test showed that rainfall slightly increased during the study years; however, the annual discharge and sediment load significantly decreased. The annual suspended sediment yield of the Du catchment varied between 1.3 × 108 and 1.0 × 1010 kg, and that of the sub-catchment varied between 6.3 × 107 and 4.3 × 109 kg. The SSCs in the catchment and sub-catchment fluctuated between 1 and 22400 g m-3 and between 1 and 31800 g m-3, respectively. The mean SSC of the Du catchment was relatively stable during the three periods (±83 g m-3). ANOVA (analysis of variance) indicated that the SSC did not significantly change under cultivation for low and moderate flows, but was significantly different under high flow during reforestation of the Du catchment. The SSC in the sub-catchment was more variable, and the mean SSC in the sub-catchment varied from 1058 ± 2217 g m-3 in the 1980s to 1256 ± 2496 g m-3 in the 1990s and 891 ± 1558 g m-3 in the 2000s. Reforestation significantly decreased the SSCs during low and moderate flows, whereas cultivation increased the SSCs during high flow. The sediment rating curves showed a stable relationship between the SSC and Q in the Du catchment during the three periods. However, the SSC-Q of the sub-catchment exhibited

  12. The impact of different sediment concentrations and sediment transport formulas on the simulated floodplain processes

    NASA Astrophysics Data System (ADS)

    Benjankar, Rohan; Yager, Elowyn M.

    2012-07-01

    SummaryOverbank sedimentation is an important process in river floodplain ecosystems and is a component of the floodplain geomorphologic evolution. The impact of suspended sediment supply on floodplain processes is still unclear because sediment deposition can be influenced by many factors. We quantified the effect of sediment supply (suspended sediment) and transport formulas on simulated floodplain processes using a coupled two-dimensional hydrodynamic and sediment transport model (MIKE21C). Erosion and deposition depths, net sedimentation depth and total volume were quantified based on the last time step of the simulation period. The MIKE21C model was validated by comparing simulated water surface elevations to those from a one-dimensional hydrodynamic model. We compared the sediment transport model simulated suspended sediment concentrations (SSCs) to measured concentrations at a gage station. Erosion and deposition processes were simulated using five hydrograph scenarios as a function of high and low SSC and two sediment transport equations, Van Rijn (1984) and Engelund and Hansen (1967). A specific location could be an erosional or depositional zone at different time steps of the simulation. Thus, floodplain deposition is a discontinuous function of river discharge and varies spatially and temporally over the floodplain. Large flows with high SSC were more effective for floodplain deposition than lower discharges, which dominantly caused sediment scour. Coupled hydrodynamic and sediment transport models that account for feedback processes between topography and hydraulics should be given first preference for future floodplain restoration projects. From a restoration perspective, larger flows are required for greater floodplain deposition rates and maintenance of dynamic processes. The Engelund and Hansen (1967) equation simulated higher transport rates than the Van Rijn equation (1984). For future studies, transport equations should be selected based on the

  13. Assessment of crude oil biodegradation in arctic seashore sediments: effects of temperature, salinity, and crude oil concentration.

    PubMed

    Sharma, Priyamvada; Schiewer, Silke

    2016-08-01

    The expected increase in offshore oil exploration and production in the Arctic may lead to crude oil spills along arctic shorelines. To evaluate the potential effectiveness of bioremediation to treat such spills, oil spill bioremediation in arctic sediments was simulated in laboratory microcosms containing beach sediments from Barrow (Alaska), spiked with North Slope Crude, and incubated at varying temperatures and salinities. Biodegradation was measured via respiration rates (CO2 production); volatilization was quantified by gas chromatography/mass spectrophotometry (GC/MS) analysis of hydrocarbons sorbed to activated carbon, and hydrocarbons remaining in the sediment were quantified by GC/flame ionization detector (FID). Higher temperature leads to increased biodegradation by naturally occurring microorganisms, while the release of volatile organic compounds was similar at both temperatures. Increased salinity had a small positive impact on crude oil removal. At higher crude oil dosages, volatilization increased, however CO2 production did not. While only a small percentage of crude oil was completely biodegraded, a larger percentage was volatilized within 6-9 weeks. PMID:27072034

  14. The effects of unpaved roads on suspended sediment concentration of third- to fifth-order streams- A case study from southern Brazil

    NASA Astrophysics Data System (ADS)

    Thomaz, E. L.; Vestena, L. R.; Ramos-Scharron, C. E.

    2012-12-01

    Unpaved roads have earned a reputation of inducing adverse effects on downstream water resources by increasing suspended sediment concentration because they typically generate sediment at rates up to several orders of magnitude above background and because they may enhance the efficiency of sediment delivery to fluvial networks. Although much research has been conducted on road effects in forested landscapes, proper understanding of their hydro-geomorphic role in rural areas is still desired. Unpaved roads are fundamental in the agricultural systems employed for the cultivation of maize and black beans on topographically-steep, marginal lands of southern Brazil. Marginal lands generate a sizeable fraction of the agricultural production in the state of Paraná, one of Brazil's agricultural powerhouses. This study documents the localized impacts on suspended sediment concentration of seven unpaved road crossings in the Guarabiroba River Catchment, Paraná, Brazil. A total of 156 suspended sediment samples were manually collected both upstream and downstream of road-crossings between 22-Apr-09 and 26-Apr-10 during 14 rainfall events ranging between 16 and 96 mm in total rainfall. The average length of road directly delivering runoff to each crossing varied from 0.56 - 2.4 km, and the size of the catchment areas of the third to fifth order monitored streams ranged from 0.3 to 13.5 km2. In addition to stream samples, 78 samples representing unpaved road runoff were collected during the same rain events. Upstream and downstream mean concentration values were compared for each storm at every site based on a paired t-test analysis (0.05% level). Mean suspended sediment concentration at stream segments located upstream of road crossings was 0.04 mg L-1 (s.d. = 0.05 mg L-1), while the mean downstream concentration was 0.11 mg L-1 (s.d. = 0.14 mg L-1) or 2.9 times higher than upstream samples. Meanwhile, road runoff had an average concentration of 0.93 mg L-1 (s.d. = 0.97 mg

  15. Monitoring the effects of disposal of fine sediments from maintenance dredging on suspended particulate matter concentration in the Belgian nearshore area (southern North Sea).

    PubMed

    Fettweis, Michael; Baeye, Matthias; Francken, Frederic; Lauwaert, Brigitte; Van den Eynde, Dries; Van Lancker, Vera; Martens, Chantal; Michielsen, Tinne

    2011-02-01

    The impact of continuous disposal of fine-grained sediments from maintenance dredging works on the suspended particulate matter concentration in a shallow nearshore turbidity maximum was investigated during dredging experiment (port of Zeebrugge, southern North Sea). Before, during and after the experiment monitoring of SPM concentration using OBS and ADV altimetry was carried out at a location 5 km west of the disposal site. A statistical analysis, based on the concept of populations and sub-sampling, was applied to evaluate the effect. The data revealed that the SPM concentration near the bed was on average more than two times higher during the dredging experiment. The disposed material was mainly transported in the benthic layer and resulted in a long-term increase of SPM concentration and formation of fluid mud layers. The study shows that SPM concentration can be used as an indicator of environmental changes if representative time series are available. PMID:21122880

  16. Sedimentation of multisized particles in concentrated suspensions

    SciTech Connect

    Selim, M.S.; Kothari, A.C.; Turian, R.M.

    1983-11-01

    A model is developed for predicting the sedimentation velocity in suspensions of multisized nonflocculating solids, in which the retarding effect of the smaller particles on the setting velocities of the larger ones is taken into account. Tests of the model, and comparisons with other models, demonstrate that it provides improved prediction of data on suspensions comprising both discrete particle size mixtures and continuous size distributions, and that it is applicable to continuous countercurrent solid-liquid operations.

  17. Effects of near-bottom water oxygen concentration on biogeochemical cycling of C, N and S in sediments of the Gulf of Gdansk (southern Baltic)

    NASA Astrophysics Data System (ADS)

    Lukawska-Matuszewska, Katarzyna; Kielczewska, Joanna

    2016-04-01

    Sediments from four sampling sites in the Gulf of Gdansk were sampled to test how different oxygen concentrations in near-bottom water affects biogeochemical cycling of C, N and S. Vertical distributions of content of organic carbon (OC), total nitrogen (TN) and total sulfur (TS) and number of sulfate-reducing bacteria (SRB) in sediments were determined. Pore water total alkalinity (TA), dissolved inorganic carbon (DIC), sulfate, hydrogen sulfide, ammonium and phosphate were analyzed and benthic fluxes of DIC, hydrogen sulfide and ammonium were calculated. Concentrations of OC and TN decreased and concentration of TS increased with sediment depth. Highest concentrations of OC, TN and TS were observed in silty clay sediments from hypoxic and anoxic sediments below the permanent halocline. Organic matter (OM) accumulation in sediments and oxygen deficiency in near-bottom water stimulate preservation of OC and burial of TS in this area. Concentrations of TA, DIC, hydrogen sulfide, ammonium and phosphate in pore water increased, while concentration of sulfate decreased with sediment depth. Hydrogen sulfide, ammonium and phosphate was a significant additional source of TA in pore water under hypoxic and anoxic conditions. Mineralization of OM at oxygen concentrations <2 ml l-1 occurred mainly via bacterial sulfate reduction. Diurnal hydrogen sulfide fluxes under hypoxic conditions ranged from 400 to 1240 μmol m-2 d-1. Ammonium fluxes were estimated on 534 - 924 μmol m-2 d-1. Corresponding fluxes measured under anoxic conditions were 266 μmol m-2 d-1 and 106 μmol m-2 d-1. Sediments under oxic conditions became a place of the intensive regeneration of carbon - DIC flux from sediment reached 2775 μmol m-2 day-1. Sediment-water DIC fluxes under hypoxic and anoxic conditions were much lower and ranged from 1015 to 1208 μmol m-2 d-1.

  18. Dissolved Concentrations of PAHs and PCBs Are Often Over-predicted Using Sediment Concentrations and Literature Koc Values

    EPA Science Inventory

    There is an increasing amount of chemical and biological evidence that using sediment concentrations and commonly applied Koc values frequently overpredicts interstitial water concentrations of HOCs, and thereby overestimates uptake and/or effects of those chemicals on exposed or...

  19. A study of flow in alluvial channels: the effect of large concentrations of fine sediment on the mechanics of flow in a small flume

    USGS Publications Warehouse

    Haushild, William Leland; Simons, Daryl Baldwin; Richadrson, Everett V.

    concentration with the dune bed form and was increased by as much as 550 percent for the transition, standing wave, and antidune forms of bed roughness. Resistance to flow was less (C/√ g increased by 45 percent) with fine sediment-laden flow than with clear-water flow for the dune, and transition bed forms; and was greater (C/√ g   reduced by 25 percent) for the standing waves and the antidunes. A narrow range of bentonite concentration for each form of bed roughness was established as a limit below which only minor changes in bed form, bed material transport, and resistance to flow occurred. The variation of the liquid properties, specific weight and viscosity, for water-bentonite dispersions were studied and their effect on the properties of the bed material particles measured. The fall velocity of the particles in a dispersion of 100, 000 parts per million fine sediment in water was reduced to about one-half their fall velocity in clear water.

  20. Sediment acoustic index method for computing continuous suspended-sediment concentrations

    USGS Publications Warehouse

    Landers, Mark N.; Straub, Timothy D.; Wood, Molly S.; Domanski, Marian M.

    2016-01-01

    Once developed, sediment acoustic index ratings must be validated with additional suspended-sediment samples, beyond the period of record used in the rating development, to verify that the regression model continues to adequately represent sediment conditions within the stream. Changes in ADVM configuration or installation, or replacement with another ADVM, may require development of a new rating. The best practices described in this report can be used to develop continuous estimates of suspended-sediment concentration and load using sediment acoustic surrogates to enable more informed and accurate responses to diverse sedimentation issues.

  1. Adsorption and transport of As (V) in soil columns: Effect of As concentration, pH and sediment properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It has been proposed that ground water contaminated with low concentrations of As (V) be remediated by infiltration and recharge into infiltration basins using the subsurface materials to adsorb the metal. This low cost remediation scheme allows for production of water that meets the drinking water ...

  2. Mercury Concentrations in Coastal Sediment from Younger Lagoon, Central California

    NASA Astrophysics Data System (ADS)

    Hohn, R. A.; Ganguli, P. M.; Swarzenski, P. W.; Richardson, C. M.; Merckling, J.; Johnson, C.; Flegal, A. R.

    2013-12-01

    Younger Lagoon Reserve, located in northern Monterey Bay, is one of the few relatively undisturbed wetlands that remain along the Central Coast of California. This lagoon system provides protected habitat for more than 100 bird species and for populations of fish, mammals, and invertebrates. Total mercury (HgT) concentrations in water within Younger Lagoon appear to vary with rainfall conditions and range from about 5-15 pM. These concentrations are similar to HgT in water from six nearby lagoon systems. However, Younger Lagoon contains elevated concentrations of dissolved organic carbon (~1 mM) and monomethylmercury (MMHg, ~1 pM) relative to our comparison lagoon sites (DOC < 0.5 mM and MMHg < 0.5 pM). We attribute Younger Lagoon's high DOC and MMHg to its restricted connection to the ocean and minor riverine contribution. Coastal lagoons in this region typically form at the mouth of streams. They behave as small estuaries during the wet season when surface water discharge keeps the mouth of the stream open to the ocean, and then transition into lagoons in the dry season when a sand berm develops and effectively cuts off surface water exchange. At Younger Lagoon, the sand berm remains intact throughout the year, breaching only during particularly high tides or intense rain events. Therefore, the lagoon's connection to nearshore seawater is primarily via surface water - groundwater interaction through the sand berm. Because Younger Lagoon is largely isolated from a surface water connection with the ocean, runoff from upgradient urban and agricultural land has an enhanced impact on water (and presumably sediment) quality. As a result, the lagoon is eutrophic and experiences annual algal blooms. Groundwater surveys suggest surface water, groundwater, and coastal seawater are hydraulically connected at Younger Lagoon, and mixing among these water masses appears to influence water geochemistry. To date, no chemical analyses have been conducted on sediment from Younger

  3. The concentration instability of a sedimenting suspension of flexible fibers

    NASA Astrophysics Data System (ADS)

    Manikantan, Harishankar; Li, Lei; Spagnolie, Saverio; Saintillan, David

    2014-11-01

    The stability of a dilute suspension of sedimenting flexible fibers is studied theoretically. Fiber compliance causes individual particles to reorient while sedimenting in a quiescent fluid. We incorporate the rate of reorientation for weakly flexible fibers into a mean-field model to study the stability of a suspension of such fibers to perturbations in concentration. Fiber flexibility is shown to have two opposing effects on suspension stability. First, it establishes a base state that is anisotropic in orientation distribution. We show that such a base state is more prone to a concentration instability than an isotropic distribution, and we illustrate the underlying mechanism. Second, the proclivity of particles to reorient due to flexibility hinders horizontal migration - a key ingredient of the instability mechanism - and suppresses the growth of concentration fluctuations. We analyze this effect by extending our theory to the next order in fiber flexibility, and indeed the growth rate of perturbations is shown to decrease for more compliant fibers. In a Brownian suspension, the dominant effect depends on the relative scales of rotational diffusion and flexibility-induced reorientation.

  4. Sediment concentration rating curves for a monsoonal climate: upper Blue Nile

    NASA Astrophysics Data System (ADS)

    Moges, Mamaru A.; Zemale, Fasikaw A.; Alemu, Muluken L.; Ayele, Getaneh K.; Dagnew, Dessalegn C.; Tilahun, Seifu A.; Steenhuis, Tammo S.

    2016-07-01

    Information on sediment concentration in rivers is important for design of reservoirs and for environmental applications. Because of the scarcity of continuous sediment data, methods have been developed to predict sediment loads based on few discontinuous measurements. Traditionally, loads are being predicted using rating curves that relate sediment load to discharge. The relationship assumes inherently a unique relationship between concentration and discharge and therefore although performing satisfactorily in predicting loads, it may be less suitable for predicting concentration. This is especially true in the Blue Nile Basin of Ethiopia where concentrations decrease for a given discharge with the progression of the rainy monsoon phase. The objective of this paper is to improve the sediment concentration predictions throughout the monsoon period for the Ethiopian highlands with a modified rating type equation. To capture the observed sediment concentration pattern, we assume that the sediment concentration was at the transport limit early in the rainy season and then decreases linearly with effective rainfall towards source-limited concentration. The modified concentration rating curve was calibrated for the four main rivers in the Lake Tana basin where sediment concentrations affect fish production and tourism. Then the scalability of the rating type equation was checked in three 100 ha watersheds for which historic data were available. The results show that for predicting sediment concentrations, the (modified) concentration rating curve was more accurate than the (standard) load rating curve as expected. In addition loads were predicted more accurately for three of the four rivers. We expect that after more extensive testing over a wider geographical area, the proposed concentration rating curve will offer improved predictions of sediment concentrations in monsoonal climates.

  5. The effect of the "Great Flood of 1993" on subsequent suspended sediment concentrations and fluxes in the Mississippi River Basin, USA

    USGS Publications Warehouse

    Horowitz, A.J.

    2006-01-01

    During the spring/summer of 1993, the upper Midwestern USA experienced unusually heavy precipitation (200-350% above normal). More than 500 gauging stations in the region were simultaneously above flood stage, and nearly 150 major rivers and tributaries over-topped their banks. This was one of the costliest floods in the history of the USA, and came to be known as the "Great Flood of 1993". An examination of the long-term daily sediment record for the Mississippi River at Thebes, Illinois (representing the middle, or lower part of the upper basin), indicates that the flood had a severe and long-lasting impact on subsequent suspended sediment concentrations (SSC) and annual suspended sediment fluxes in the basin. At Thebes, pre1993 (1981-1992) median discharge and SSC were about 5400 m3 s-1 and 304 mg L-1, respectively; whereas, post-1993 (1994-2004) median discharge and SSC were about 5200 m3 s-1 and 189 mg L-1, respectively. Clearly, the 1993 flood removed substantial amounts of "stored" bed sediment and/or readily erodible flood plain deposits, eliminating a major source of SSC for the Thebes site. Examination of additional, but discontinuous sediment records (covering the period from 1981-2004) for other sites in the basin indicates that current post-flood declines in SSC and suspended sediment fluxes range from a low of about 10% to a high of about 36%.

  6. The effects of exploratory petroleum drilling in the northwest Gulf of Mexico on trace metal concentrations in near rig sediments and organisms

    SciTech Connect

    Boothe, P.N.; Presley, B.J. )

    1987-01-01

    For a typical offshore petroleum well, 500-1000 t (dry weight excluding cuttings) of drilling fluid solids are discharged into the sea. In this study, concentrations of selected trace elements present in drilling fluids (Ba, Cd, Cr, Cu, Fe, Pb, Ni, V), were determined in surface sediments and macroepifauna around a Gulf of Mexico exploratory drilling site before, during, and after drilling operations. Observed significant increases in the levels of Fe in organisms and Ba and Cr in sediments were attributable to drilling discharges. Shrimp, which constitute the largest commercial fishery in the region, were intensively studied. Shrimp collected during the last few days of drilling had abdominal muscle Fe concentrations more than twice those in shrimp sampled before or after drilling. Enhanced Fe solubility (bioavailability) in sea-water, caused by soluble organic chelating agents in the drilling fluids, is the most likely explanation for the observed increases. Significant increases in sediment Ba were observed at all sampling radii but large increases (up to 7.5 fold) were only observed within a few hundred meters of the drilling site. An accurate mass balance of total discharged (excess) Ba present in sediments within 1000 m of the drilling site was determined. Only 9.3% of the total Ba used, and presumably other similar drilling mud components traced by Ba, was present within 1000 m at the conclusion of drilling. After 2.6 mo. only 6.6% was present. Significant sediment resuspension and transport occurring in the high current nearshore study site (24 m water depth) was responsible for the low retention and rapid loss of discharged Ba in the sediment. The largest mean increase in sediment Cr (26%) occurred at the 1,000 m sampling radii.

  7. An investigation on the estimation of sediment concentration by artificial neural networks

    NASA Astrophysics Data System (ADS)

    Chen, A.; Chiang, Y.; Chang, S.; Chang, F.

    2010-12-01

    Estimation of sediment concentration in reservoirs, one of the important issues for watershed planning in Taiwan, is closely related to the water resources management in upstream river. It is difficult to continuously and effectively measure the sediment in the watershed. Furthermore, traditional methods such as regression analysis and sediment rating curve are not able to provide effective simulation of sediment concentration. As a result, there is a necessity of establishing an accurate model for estimating sediment concentration. The daily streamflow and sediment concentration data measured at Hsia-Yun gauging stations and precipitation data measured at 16 rainfall gauging stations in Shihmen Reservoir were collected in the years of 1982-2006. In this study, a total of 484 datasets were the inputs to an artificial neural network (ANN), in which 316, 77 and 91 datasets were arranged for model training, validation and testing accordingly. The artificial neural network was applied to estimating sediment concentration at Hsia-Yun gauging station. Results obtained from ANN were compared with those of conventional methods. The investigation revealed that the ANN provided a coefficient of efficiency of 0.77 in testing phase and performed much better than sediment rating curve. Keywords: watershed management, river sediment concentration, artificial neural network(ANN).

  8. Sediment concentration rating curves for a monsoonal climate: upper Blue Nile Basin

    NASA Astrophysics Data System (ADS)

    Moges, M. A.; Zemale, F. A.; Alemu, M. L.; Ayele, G. K.; Dagnew, D. C.; Tilahun, S. A.; Steenhuis, T. S.

    2015-12-01

    Information on sediment content in rivers is important for design of reservoirs and for environmental applications. Because of scarcity of continuous sediment data, methods have been developed to predict sediment loads based on few discontinuous measurements. Traditionally, loads are being predicted using rating curves that relate sediment load to discharge. The relationship assumes inherently a unique relationship between concentration and discharge and therefore although performing satisfactorily in predicting loads, it may be less suitable for predicting concentration. This is especially true in the Blue Nile basin of Ethiopia where concentrations decrease for a given discharge with the progression of the rainy monsoon phase. The objective of this paper is to improve the sediment concentration predictions throughout the monsoon period for the Ethiopian highlands with a modified rating type equation. To capture the observed sediment concentration pattern, we assume that the sediment concentration was at the transport limit early in the rainy season and then decrease linearly with effective rainfall towards source limited concentration. The modified concentration rating curve was calibrated for the four main rivers in the Lake Tana basin where sediment concentrations affect fish production and tourism. Then the scalability of the rating type equation was checked in three 100-ha watersheds for which historic data was available. The results show, that for predicting sediment concentrations, the (modified) concentration rating curve was more accurate than the (standard) load rating curve as expected. In addition loads were predicted more accurately for three of the four rivers. We expect that after more extensive testing over a wider geographical area, the proposed concentration rating curve will offer improved predictions of sediment concentrations in monsoonal climates.

  9. Heavy metal concentrations in natural and human-impacted sediments of Segara Anakan Lagoon, Indonesia.

    PubMed

    Syakti, A D; Demelas, C; Hidayati, N V; Rakasiwi, G; Vassalo, L; Kumar, N; Prudent, P; Doumenq, P

    2015-01-01

    The concentrations of eight elements (Cr, Cu, Fe, Mn, Ni, Ti, V, and Zn) in surface sediments from Segara Anakan Nature Reserve (SARN), Indonesia, were determined using inductively coupled plasma-atomic emission spectroscopy following microwave-assisted acid digestion. In general, the heavy metal concentrations of the sediments were found to decrease in the sequence Fe > Ti > Mn > Zn > V > Cu > Cr > Ni. Sediment pollution assessment was carried out using a pollution status index contamination factor, pollution load index, geoaccumulation index, and enrichment factor as well as by comparing the measured values with two sediment quality guidelines, i.e., threshold effect level and probable effect level. The evaluation showed that in the refinery site stations, Cr, Ni, and Zn concentrations found in the SANR sediments may cause the adverse effect to occur over a wider range of organisms and can contribute to a more serious harmful effect. PMID:25492704

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

    USGS Publications Warehouse

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

    1997-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1997-03-01

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

  12. Extraction and concentration of phenolic compounds from water and sediment

    USGS Publications Warehouse

    Goldberg, M.C.; Weiner, Eugene R.

    1980-01-01

    Continuous liquid-liquid extractors are used to concentrate phenols at the ??g l-1 level from water into dichloromethane; this is followed by Kuderna-Danish evaporative concentration and gas chromatography. The procedure requires 5 h for 18 l of sample water. Overall concentration factors around 1000 are obtained. Overall concentration efficiencies vary from 23.1 to 87.1%. Concentration efficiencies determined by a batch method suitable for sediments range from 18.9 to 73.8%. ?? 1980.

  13. Effect of environmental setting on sediment, nitrogen, and phosphorus concentrations in Albemarle-Pamlico drainage basin, North Carolina and Virginia, USA

    USGS Publications Warehouse

    McMahon, G.; Harned, D.A.

    1998-01-01

    Environmental settings were defined, through an overlay process, as areas of coincidence between categories of three mapped variables - land use, surficial geology, and soil drainage characteristics. Expert judgment was used in selecting factors thought to influence sediment and nutrient concentrations in the Albemarle-Pamlico drainage area. This study's findings support the hypothesis that environmental settings defined using these three variables can explain variations in the concentration of certain sediment and nutrient constituents. This finding underscores the importance of developing watershed management plans that account for differences associated with the mosaic of natural and anthropogenic factors that define a basin's environmental setting. At least in the case of sediment and nutrients in the Albemarle-Pamlico region, a watershed management plan that focuses only on anthropogenic factors, such as point-source discharges, and does not account for natural characteristics of a watershed and the influences of these characteristics on water quality, may lead to water-quality goals that are over- or underprotective of key environmental features and to a misallocation of the resources available for environmental protection.

  14. Effect of environmental setting on sediment, nitrogen, and phosphorus concentrations in Albemarle-Pamlico drainage basin, North Carolina and Virginia, USA

    SciTech Connect

    McMahon, G.; Harned, D.A.

    1998-11-01

    Environmental settings were defined, through an overlay process, as areas of coincidence between categories of three mapped variables--land use, surficial geology, and soil drainage characteristics. Expert judgment was used in selecting factors thought to influence sediment and nutrient concentrations in the Albemarle-Pamlico drainage area. This study`s findings support the hypothesis that environmental settings defined using these three variables can explain variations in the concentration of certain sediment and nutrient constituents. This finding underscores the importance of developing watershed management plans that account for differences associated with the mosaic of natural and anthropogenic factors that define a basin`s environmental setting. At least in the case of sediment and nutrients in the Albemarle-Pamlico region, a watershed management plan that focuses only on anthropogenic factors, such as point-source discharges, and does not account for natural characteristics of a watershed and the influences of these characteristics on water quality, may lead to water-quality goals that are over- or underprotective of key environmental features and to a misallocation of the resources available for environmental protection.

  15. Trace metal concentrations in tropical mangrove sediments, NE Brazil.

    PubMed

    Miola, Brígida; Morais, Jáder Onofre de; Pinheiro, Lidriana de Souza

    2016-01-15

    Sediment cores were taken from the mangroves of the Coreaú River estuary off the northeast coast of Brazil. They were analyzed for grain size, CaCO3, organic matter, and trace metal (Cd, Pb, Zn, Cu, Al, and Fe) contents. Mud texture was the predominant texture. Levels of trace metals in surface sediments indicated strong influence of anthropogenic processes, and diagenetic processes controlled the trace metal enrichment of core sediments of this estuary. The positive relationships between trace metals and Al and Fe indicate that Cu, Zn, Pb, and Cd concentrations are associated mainly with Al and Fe oxy-hydroxides and have natural sources. PMID:26608507

  16. Dietary assimilation of cadmium associated with bacterial exopolymer sediment coatings by the estuarine amphipod Leptocheirus plumulosus: Effects of Cd concentration and salinity

    USGS Publications Warehouse

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

    1999-01-01

    Bacterial extracellular substances (also known as exopolysaccharides, or EPS) may serve as vectors for trophic transfer of metals in benthic systems because these ubiquitous sediment coatings can sorb high concentrations of toxic metals, and because many benthic invertebrates assimilate EPS sediment coatings upon ingestion. We conducted 3 sets of experiments to determine the assimilative bioavailability of EPS-associated Cd to the benthic amphipod Leptocheirus plumulosus as a function of Cd concentration and salinity. Bioavailability was measured as L. plumulosus Cd assimilation efficiency (AE) from EPS-coated silica (EPS-Si) and from uncoated silica (NC-Si) using modified pulse-chase methods with the gamma-emitting radioisotope 109Cd. Cd AE was significantly greater from NC-Si than from EPS-Si at 7.5???, but not at 2.5 or 25???. Overall, Cd AE from EPS-Si was between 15.1 and 21.5%. Because EPS-Si sorbed more Cd than NC-Si, EPS coatings magnified the amount of Cd amphipods accumulated at each salinity by up to a factor of 10. Salinity did not directly affect Cd AE from EPS-Si, but because Cd-EPS partitioning increased with decreasing salinity, amphipods accumulated more Cd from EPS at the lowest Cd-EPS incubation salinity (2.5 ???) than at higher salinities (7.5 and 25 ???). Finally, Cd concentration in EPS exhibited an inverse relationship with Cd AE at 2.5 ???, but not at 25 ???. Specifically, Cd AE was 12 times greater at 1 compared with 10 ??g Cd ??g-1 EPS. Together, these results show that estuarine benthos can accumulate Cd from EPS sediment coatings, but that the degree to which this phenomenon occurs is dependent upon seawater salinity and Cd concentration in EPS.

  17. The effects of sediment and mercury mobilization in the South Yuba River and Humbug Creek Confluence Area, Nevada County, California: Concentrations, speciation, and environmental fate-Part 1: Field characterization

    USGS Publications Warehouse

    Fleck, Jacob A.; Alpers, Charles N.; Marvin-DiPasquale, Mark; Hothem, Roger L.; Wright, Scott A.; Ellett, Kevin; Beaulieu, Elizabeth; Agee, Jennifer L.; Kakouros, Evangelos; Kieu, Le H.; Eberl, Dennis D.; Blum, Alex E.; May, Jason T.

    2011-01-01

    Millions of pounds of mercury (Hg) were deposited in the river and stream channels of the Sierra Nevada from placer and hard-rock mining operations in the late 1800s and early 1900s. The resulting contaminated sediments are relatively harmless when buried and isolated from the overlying aquatic environment. The entrained Hg in the sediment constitutes a potential risk to human and ecosystem health should it be reintroduced to the actively cycling portion of the aquatic system, where it can become methylated and subsequently bioaccumulated in the food web. Each year, sediment is mobilized within these fluvial systems during high stormflows, transporting hundreds of tons of Hg-laden sediment downstream. The State of California and resource-management agencies, including the Bureau of Land Management (BLM) and the U.S. Forest Service, are concerned about additional disturbances, such as from suction gold dredging activities, which have the potential to mobilize Hg associated with buried sediment layers elevated in Hg that are otherwise likely to remain buried under normal storm conditions. The BLM initiated a study looking at the feasibility of removing Hg-contaminated sediment at the confluence of the South Yuba River and Humbug Creek in the northern Sierra Nevada of California by using standard suction-dredge technology. Additionally, the California State Water Resources Control Board (SWRCB) supported a comprehensive characterization of the intended dredge site. Together, the BLM and SWRCB supported a comprehensive characterization of Hg contamination at the site and the potential effects of sediment disturbance at locations with historical hydraulic mining debris on downstream environments. The comprehensive study consisted of two primary components: field studies and laboratory experiments. The field component, described in this report, had several study elements: 1) a preliminary, small-scale, in-stream dredge test; 2) comprehensive characterization of grain

  18. Calibration of Optical Back Scatterance for Suspended Sediment Concentration With San Francisco Bay Sediment

    NASA Astrophysics Data System (ADS)

    Keller, B.

    2005-12-01

    Optical back scatterance (OBS) is used by USGS to indirectly quantify suspended sediment concentration in the waters of San Francisco Bay. The use of one of the types of OBS instruments that is used in the Bay was evaluated for quantification of discharge water from sand yards, where dredged bay floor sand is brought on land for commercial purposes. The instrument response was calibrated with synthetic samples prepared from settled, previously suspended fine sediment, collected on various dates and derived from the same general area of central San Francisco Bay. The sediment samples were washed with fresh water, oven dried, sieved, and mixed into water in a test chamber. The responses of various sediment samples were compared with that of silica flour, a commercially available industrial material with similar particle size and density, that is white in color. Multiple tests with sediment samples from individual dates yielded extremely repeatable, almost linear instrument responses as a function of varying concentration. Sediment samples from different dates yielded varying responses, ranging from 2.0 to 2.8 times the response of silica flour. This response difference, a factor of approximately 1.4, is interpreted to be due to small differences in the darkness ("color") of the sediment samples. In a comparison with an EPA test method that uses filtration and weighing, performed at commercial laboratories, the "total suspended solids" (TSS, used synonymously with the term "suspended sediment concentration") analyses of the mixed synthetic sample waters yielded very poor results. Saline water samples were often associated with TSS test results that were higher than the known synthetic sample concentrations, indicating that the lab tests were often measuring dissolved salt rather than suspended sediment.

  19. An evaluation of sediment rating curves for estimating suspended sediment concentrations for subsequent flux calculations

    USGS Publications Warehouse

    Horowitz, A.J.

    2003-01-01

    In the absence of actual suspended sediment concentration (SSC) measurements, hydrologists have used sediment rating (sediment transport) curves to estimate (predict) SSCs for subsequent flux calculations. Various evaluations of the sediment rating-curve method were made using data from long-term, daily sediment-measuring sites within large (>1 000 000 km2), medium ( 1000 km2), and small (<1000 km2) river basins in the USA and Europe relative to the estimation of suspended sediment fluxes. The evaluations address such issues as the accuracy of flux estimations for various levels of temporal resolution as well as the impact of sampling frequency on the magnitude of flux estimation errors. The sediment rating-curve method tends to underpredict high, and overpredict low SSCs. As such, the range of errors associated with concomitant flux estimates for relatively short time-frames (e.g. daily, weekly) are likely to be substantially larger than those associated with longer time-frames (e.g. quarterly, annually) because the over- and underpredictions do not have sufficient time to balance each other. Hence, when error limits must be kept under ??20%, temporal resolution probably should be limited to quarterly or greater. The evaluations indicate that over periods of 20 or more years, errors of <1% can be achieved using a single sediment rating curve based on data spanning the entire period. However, somewhat better estimates for the entire period, and markedly better annual estimates within the period, can be obtained if individual annual sediment rating curves are used instead. Relatively accurate (errors sediment fluxes can be obtained from hydrologically based monthly measurements/samples. For 5-year periods or longer, similar results can be obtained from measurements/samples collected once every 2 months. In either case, hydrologically based sampling, as opposed to calendar-based sampling is likely to limit the magnitude of flux estimation

  20. Acetate concentrations and oxidation in salt marsh sediments

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Acetate concentrations and rates of acetate oxidation and sulfate reduction were measured in S. alterniflora sediments in New Hampshire and Massachusetts. Pore water extracted from cores by squeezing or centrifugation contained in greater than 0.1 mM acetate and, in some instances, greater than 1.0 mM. Pore water sampled nondestructively contained much less acetate, often less than 0.01 mM. Acetate was associated with roots, and concentrations varied with changes in plant physiology. Acetate turnover was very low whether whole core or slurry incubations were used. Radiotracers injected directly into soils yielded rates of sulfate reduction and acetate oxidation not significantly different from core incubation techniques. Regardless of incubation method, acetate oxidation did not account for a substantial percentage of sulfate reduction. These results differ markedly from data for unvegetated coastal sediments where acetate levels are low, oxidation rate constants are high, and acetate oxication rates greatly exceed rates of sulfate reduction. The discrepancy between rates of acetate oxidation and sulfate reduction in these marsh soils may be due either to the utilization of substrates other than acetate by sulfate reducers or artifacts associated with measurements of organic utilization by rhizosphere bacteria. Care must be taken when interpreting data from salt marsh sediments since the release of material from roots during coring may affect the concentrations of certain compounds as well as influencing results obtained when sediment incubations are employed.

  1. Rate of strontium sorption and the effects of variable aqueous concentrations of sodium and potassium on strontium distribution coefficients of a surficial sediment at the Idaho National Engineering Laboratory, Idaho

    USGS Publications Warehouse

    Bunde, R.L.; Rosentreter, J.J.; Liszewski, M.J.

    1998-01-01

    The rate of strontium sorption and the effects of variable aqueous concentrations of sodium and potassium on strontium sorption were measured as part of an investigation to determine strontium chemical transport properties of a surficial sediment at the Idaho National Engineering Laboratory (INEL), Idaho. Batch experimental techniques were used to determine the rate of strontium sorption and strontium distribution coefficients (K(d)s) between aqueous and solid phases. Rate experiments indicate that strontium in solution reached an apparent equilibrium with the sediment in 26 h. K(d)s were derived using the linear isotherm model at initial sodium concentrations from 100 to 5,000 mg/l and initial potassium concentrations from 2 to 150 mg/l. K(d)s ranged from 56 ?? 2 to 62 ?? 3 ml/g at initial aqueous concentrations of sodium and potassium equal to or less than 300 and 150 mg/l, respectively. K(d)s hinged from 4.7 ?? 0.2 to 19 ?? 1 ml/g with initial aqueous concentrations of sodium between 1,000 and 5,000 mg/l. These data indicate that sodium concentrations greater than 300 mg/l in wastewater increase the availability of strontium for transport beneath waste disposal ponds at the INEL by decreasing strontium sorption on the surficial sediment. Wastewater concentrations of sodium and potassium less than 300 and 150 mg/l, respectively, have little effect on the availability of strontium for transport.The rate of strontium sorption and the effects of variable aqueous concentrations of sodium and potassium on strontium sorption were measured as part of an investigation to determine strontium chemical transport properties of a surficial sediment at the Idaho National Engineering Laboratory (INEL), Idaho. Batch experimental techniques were used to determine the rate of strontium sorption and strontium distribution coefficients (Kds) between aqueous and solid phases. Rate experiments indicate that strontium in solution reached an apparent equilibrium with the sediment in 26

  2. Adsorption as a control of metal concentrations in sediment extracts

    SciTech Connect

    Rendell, P.S.; Batley, G.E.; Cameron, A.J.

    1980-03-01

    The adsorption of Cu, Pb, and Cd from selected extractant solutions, onto uncontaminated river sediments, has been investigated under typical extraction conditions. Significant adsorption of added metal was found to occur during overnight extraction with dilute HCl (pH>1.5), 0.1 M hydroxylamine hydrochloride (pH 2), 0.1 M sodium citrate (pH 4.6), 1 M ammonium acetate, 10% sodium citrate-1% sodium dithionite, and 25% acetic acid. Adsorption also occurred during a hydrogen peroxide digestion procedure. The inability of reagents to prevent losses of soluble metal in these experiments strongly suggests that a proportion of the metal actually released from a sediment sample during an extraction will be readsorbed. This may lead to serious misinterpretation of extraction data because the metal concentrations determined in the extract do not represent metal levels in the sediment fractions attacked.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    This review highlights the important role of the depth-averaged sediment concentration (DASC) to understand the formation of a number of coastal morphodynamic features that have an alongshore rhythmic pattern: beach cusps, surf zone transverse and crescentic bars, and shoreface-connected sand ridges. We present a formulation and methodology, based on the knowledge of the DASC (which equals the sediment load divided by the water depth), that has been successfully used to understand the characteristics of these features. These sand bodies, relevant for coastal engineering and other disciplines, are located in different parts of the coastal zone and are characterized by different spatial and temporal scales, but the same technique can be used to understand them. Since the sand bodies occur in the presence of depth-averaged currents, the sediment transport approximately equals a sediment load times the current. Moreover, it is assumed that waves essentially mobilize the sediment, and the current increases this mobilization and advects the sediment. In such conditions, knowing the spatial distribution of the DASC and the depth-averaged currents induced by the forcing (waves, wind, and pressure gradients) over the patterns allows inferring the convergence/divergence of sediment transport. Deposition (erosion) occurs where the current flows from areas of high to low (low to high) values of DASC. The formulation and methodology are especially useful to understand the positive feedback mechanisms between flow and morphology leading to the formation of those morphological features, but the physical mechanisms for their migration, their finite-amplitude behavior and their decay can also be explored.

  4. Metal concentrations in surface sediments of Boston Harbor - Changes with time

    USGS Publications Warehouse

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

    1998-01-01

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

  5. Priming effects in marine sediments

    NASA Astrophysics Data System (ADS)

    Gontikaki, Evina; Thornton, Barry; Witte, Ursula

    2013-04-01

    Continental margin sediments (<2000 m) cover merely 15 % of the ocean's seafloor but are responsible for more than 70 % of the global benthic mineralization. Understanding when these systems act as a source or sink of carbon (C) is thus of primary importance if we are to produce reliable global C budgets and predict the effects of future perturbations on the global C cycle. The chemical nature of organic matter (OM) is thought to be one of the major controls on the degradation/preservation balance in sediments; labile and refractory OM pools degrade at different rates but not independently. Priming effects (PE), i.e. changes in the decomposition of refractory organic matter following inputs of labile OM, have the potential to alter the C budget in sediments but have been largely ignored by marine scientists. Climate-driven changes in primary production, and land erosion and run-off are likely to change the quantity and composition of organic matter inputs in marine ecosystems and influence the magnitude and direction of PEs in seawater and sediments. Here, we attempt to evaluate the importance of priming effects on C cycling in marine sediments by use of labelled substrates of different quantity and quality in stable isotope tracer experiments and argue that PEs need to be incorporated in global change models.

  6. Radioisotope Concentration in Lake Sediments of Maracaibo, Venezuela

    SciTech Connect

    Salas, A. Rangel; Viloria, T.; Sajo-Bohus, L.; Barros, H.; Greaves, E. D.; Palacios, D.

    2007-10-26

    Maracaibo Lake is one of the most important water basing and oil producing regions in Venezuela. Changes in the local environment have been monitored for chemical pollution in the past. For this study we selected a set of sediment samples collected in the shore and analyzed for its radioisotope content. Results show the gamma emitting isotopes distribution. Isotopes concentrations have been determined within the natural K, Th and U families.

  7. Using ADV backscatter strength for measuring suspended cohesive sediment concentration

    NASA Astrophysics Data System (ADS)

    Ha, H. K.; Hsu, W.-Y.; Maa, J. P.-Y.; Shao, Y. Y.; Holland, C. W.

    2009-05-01

    Laboratory experiments were conducted at two institutes to reveal the relationship between acoustic backscatter strength and suspended sediment concentration (SSC). In total, three acoustic Doppler velocimeters (ADVs) with different frequencies (5, 10 and 16 MHz) were tested. Two different commercial clays and one natural sediment from Clay Bank site in the York River were checked for acoustic responses. The SSCs of selected sediments were artificially changed between a selected low and a high value in tap or de-ion water. Each ADV showed quite different backscatter responses depending on the sediment type and SSC. Not all devices had a good linear relationship between backscatter strength and SSC. Within a limited range of SSC, however, the backscatter strength can be well correlated with the SSC. Compared with optical backscattering sensor (OBS), the fluctuation of ADV backscatter signals was too noisy to be directly converted to the instantaneous changes of SSC due to high amplification ratio and small sampling volume. For the more accurate signal conversion for finding the fluctuation of SSC, the ensemble average should be applied to increase the signal-to-noise ratio. There are unexpected responses for the averaged backscatter wave strength: (1) high signals from small particles but low signals from large particles; and (2) two linear segments in calibration slope. These phenomena would be most likely caused by the different gain setting built in ADVs. The different acoustic responses to flocculation might also contribute somewhat if flocs are tightly packed. This study suggests that an ADV could be a useful instrument to estimate suspended cohesive sediment concentration and its fluctuation if the above concerns are clarified.

  8. Evaluation of suspended sediment concentrations, sediment fluxes and sediment depositions along a reservoir by using laser diffraction and acoustic backscatter data

    NASA Astrophysics Data System (ADS)

    Lizano, Laura; Haun, Stefan

    2015-04-01

    The construction of dams and reservoirs disturb the natural morphological behavior of rivers. A natural settling effect occurs due to the reduced turbulences and flow velocities. As a consequence, reservoirs fill up with sediments which results in a reduction of storage volume, influences the operation of hydropower plants and leads in several cases to flood protection problems. The sediment depositions in reservoirs are standardly evaluated by using bathymetric data, obtained by a single beam sonar from pre-defined cross sections or by an extensive evaluation of the reservoir bed by a side scan sonar. However, a disadvantage of this method is that it is not possible to evaluate the pore water content of the depositions, which may lead as consequence to an uncertainty in the measured amount of deposited sediments. Given that a major part of sediments entering reservoirs are transported in suspension, sediment flux measurements along defined transects could give more reliable information on the settled amount of sediments and additional information on the sediment transport mechanism within the reservoir. An evaluation of the sediment fluxes is in practice often conducted by a single suspended sediment concentration (SSC) measurement in combination with a cross sectional calibration factor to take changes in the SSC along the transect into account. However, these calibration factors are often developed only for one specific in-situ condition and may give unreliable results in case that the boundaries change e.g. the hydraulic conditions. Hence an evaluation of the sediment fluxes along the whole transect would give a more reliable number for the amount of transported sediments through the reservoir. This information can afterwards be used to calculate the amount of settled sediments in different sections of the reservoir and the amount of sediments which will enter the intake. For this study the suspended sediment transport within the Peñas Blancas reservoir in

  9. Biotic drivers of fluvial sediment transport: Aggregate effects of sediment mobilisation by crayfish on catchment-scale sediment yield

    NASA Astrophysics Data System (ADS)

    Rice, Stephen; Mathers, Kate; Reeds, Jake; Extence, Chris

    2015-04-01

    Small but prolific organisms may be significant zoogeomorphic agents that make cumulative contributions to the large-scale terrestrial sediment cascade in, as yet, unknown and unquantified ways. One such organism is the signal crayfish (Pacifastacus leniusculus), which has invaded many European rivers. The geographical extent and abundance of this animal ensure innumerable local, small-scale interactions with the fluvial sediment system that have the potential to yield a substantial effect when aggregated across larger spatial and temporal scales. Here we estimate, for the first time, the proportion of the total annual sediment yield associated with crayfish activity in an infested river and examine the variability in crayfish-driven sediment flux integrated across daily, monthly and seasonal time scales. We focused on one of several mechanisms by which crayfish activities affect sediment dynamics: the mobilisation of fine sediments by foraging, fighting and burrowing under hydraulic conditions that are otherwise insufficient to entrain sediment. On the Brampton Branch of the River Nene, UK, a 12-month record of suspended sediment concentration (derived from a calibration of turbidity data against measured SSC) allowed calculation of sediment fluxes and integrated sediment loads at ten-minute intervals. Concurrent measurements of water depth and crayfish movements (using PIT tagging) confirmed that night-time crayfish activity was often associated with increased sediment fluxes in the absence of any change in hydraulic conditions. Sediment loads calculated for these periods of crayfish activity were compared with total loads to estimate the contribution made to sediment mobilisation by crayfish. Crayfish-induced fluxes were most significant during summer low-flows, becoming less important during winter when the crayfish were inactive and competent high flows dominated sediment transport. Nevertheless, the seasonal cumulative effect of crayfish was substantial and

  10. Two-dimensional depth-averaged model simulation of suspended sediment concentration distribution in a groyne field

    NASA Astrophysics Data System (ADS)

    Duan, Jennifer G.; Nanda, S. K.

    2006-08-01

    SummaryRiver-training structures, such as spur dikes, are effective engineered methods used to protect banks and improve aquatic habitat. This paper reports the development and application of a two-dimensional depth-averaged hydrodynamic model to simulate suspended sediment concentration distribution in a groyne field. The governing equations of flow hydrodynamic model are depth-averaged two-dimensional Reynold's averaged momentum equations and continuity equation in which the density of sediment laden-flow varies with the concentration of suspended sediment. The depth-averaged two-dimensional convection and diffusion equation was solved to obtain the depth-averaged suspended sediment concentration. The source term is the difference between suspended sediment entrainment and deposition from bed surface. One laboratory experiment was chosen to verify the simulated flow field around a groyne, and the other to verify the suspended sediment concentration distribution in a meandering channel. Then, the model utility was demonstrated in a field case study focusing on the confluence of the Kankakee and Iroquois Rivers in Illinois, United States, to simulate the distribution of suspended sediment concentration around spur dikes. Results demonstrated that the depth-averaged, two-dimensional model can approximately simulate the flow hydrodynamic field and concentration of suspended sediment. Spur dikes can be used to effectively relocate suspended sediment in alluvial channels.

  11. A Time Series Separation and Reconstruction (TSSR) Technique to Estimate Daily Suspended Sediment Concentrations

    EPA Science Inventory

    High suspended sediment concentrations (SSCs) from natural and anthropogenic sources are responsible for biological impairments of many streams, rivers, lakes, and estuaries, but techniques to estimate sediment concentrations or loads accurately at the daily temporal resolution a...

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

    PubMed Central

    2014-01-01

    Background Coastal sediments in the northern Gulf of Mexico have a high potential of being contaminated by petroleum hydrocarbons, such as polycyclic aromatic hydrocarbons (PAHs), due to extensive petroleum exploration and transportation activities. In this study we evaluated the spatial distribution and contamination sources of PAHs, as well as the bioavailable fraction in the bulk PAH pool, in surface marsh and shelf sediments (top 5 cm) of the northern Gulf of Mexico. Results PAH concentrations in this region ranged from 100 to 856 ng g−1, with the highest concentrations in Mississippi River mouth sediments followed by marsh sediments and then the lowest concentrations in shelf sediments. The PAH concentrations correlated positively with atomic C/N ratios of sedimentary organic matter (OM), suggesting that terrestrial OM preferentially sorbs PAHs relative to marine OM. PAHs with 2 rings were more abundant than those with 5–6 rings in continental shelf sediments, while the opposite was found in marsh sediments. This distribution pattern suggests different contamination sources between shelf and marsh sediments. Based on diagnostic ratios of PAH isomers and principal component analysis, shelf sediment PAHs were petrogenic and those from marsh sediments were pyrogenic. The proportions of bioavailable PAHs in total PAHs were low, ranging from 0.02% to 0.06%, with higher fractions found in marsh than shelf sediments. Conclusion PAH distribution and composition differences between marsh and shelf sediments were influenced by grain size, contamination sources, and the types of organic matter associated with PAHs. Concentrations of PAHs in the study area were below effects low-range, suggesting a low risk to organisms and limited transfer of PAHs into food web. From the source analysis, PAHs in shelf sediments mainly originated from direct petroleum contamination, while those in marsh sediments were from combustion of fossil fuels. PMID:24641695

  13. Effect of aeration of sediment on cadmium binding

    SciTech Connect

    Zhuang, Y.; Allen, H.E.; Fu, G. . Dept. of Civil Engineering)

    1994-05-01

    Acid-volatile sulfide (AVS) has been shown to be the dominant phase reacting with metals in anoxic sediments. The AVS in sediment decreases upon resuspension due to storm and dredging, and in winter when the rate of aeration processes exceeds that of the formation of sulfide. The authors conducted a series of lab aeration experiments in batch reactors to investigate the effects of aeration of sediment on the sulfide content of sediment and on the partitioning of cadmium, a model toxic metal, to the sediment. Aeration of sediment results in rapid decrease of the AVS. The authors studied the sediment characteristics for aeration periods of approximately a month. During this time, the concentrations of dissolved metals increased by 200 to 400% or more, relative to the concentrations present at the beginning of the test. The concentration of metal associated with AVS and with pyrite decreased. During the aeration, there are increases in the concentrations of hydrous iron and manganese oxides, and these materials become increasingly more important in the binding of cadmium. Following the aeration, > 50% of the cadmium was associated with the extractable iron and manganese components of the sediment. Overall, the binding capacity of the sediments for cadmium decreased after aeration.

  14. Bioaccumulation of PCBs Across Concentration Gradients in Sediments

    EPA Science Inventory

    Sediment bioaccumulation tests with Lumbriculus variegatus quantify the relationships between the chemical residues in sediments and benthic invertebrates, and these relationships are expressed as biota-sediment accumulation factors (BSAF). At some field sites, BSAFs decr...

  15. Analysis of suspended-sediment concentrations and radioisotope levels in the Wild Rice River basin, northwestern Minnesota, 1973-98

    USGS Publications Warehouse

    Brigham, Mark E.; McCullough, Carolyn J.; Wilkinson, Philip M.

    2001-01-01

    We examined historical suspended-sediment data and activities of fallout radioisotopes (lead-210 [210Pb], cesium-137 [137Cs], and beryllium-7 [7Be]) associated with suspended sediments and source-area sediments (cultivated soils, bank material, and reference soils) in the Wild Rice River Basin, a tributary to the Red River of the North, to better understand sources of suspended sediment to streams in the region. Multiple linear regression analysis of suspended-sediment concentrations from the Wild Rice River at Twin Valley, Minnesota indicated significant relations between suspended-sediment concentrations and streamflow. Flow-adjusted sediment concentrations tended to be slightly higher in spring than summer-autumn. No temporal trends in concentration were observed during 1973-98. The fallout radioisotopes were nearly always detectable in suspended sediments during spring-summer 1998. Mean 210Pb and 7Be activities in suspended sediment and surficial, cultivated soils were similar, perhaps indicating little dilution of suspended sediment from low-isotopic-activity bank sediments. In contrast, mean 137Cs activities in suspended sediment indicated a mixture of sediment originating from eroded soils and from eroded bank material, with bank material being a somewhat more important source upstream of Twin Valley, Minnesota; and approximately equal fractions of bank material and surficial soils contributing to the suspended load downstream at Hendrum, Minnesota. This study indicates that, to be effective, efforts to reduce sediment loading to the Wild Rice River should include measures to control soil erosion from cultivated fields.

  16. Total phosphorus content of river sediments in relationship to calcium, iron and organic matter concentrations.

    PubMed

    House, William A; Denison, Frank H

    2002-01-23

    Data on the total concentrations of phosphorus, calcium, iron and organic matter in surface bed-sediments taken from rivers in the Thames catchment (Wey, Blackwater, Thame and Kennet), the River Swale in Yorkshire (data excludes the organic matter content) as well as the headwaters of the Great Ouse, are collated and compared. Total concentrations of phosphorus, iron and calcium range from 1.7-649, 12-8,333 and 9-4,605 micromol g(-1) (dry weight), respectively, with organic matter in the range of 0.6-19% by dry weight. For the Wey, Blackwater and Great Ouse, sewage inflows had no detectable effect on the sediment concentrations of total calcium, iron and organic matter whereas for the Blackwater and Great Ouse, the total phosphorus contents of the sediment were higher downstream of the effluent input in comparison with a less impacted upstream location. Relationships between the total phosphorus content of the sediments and contents of iron, calcium and organic matter indicated marked differences between the rivers. Although the organic matter content of the sediments was found to be a significant predictor for the total phosphorus concentration for the Blackwater and Great Ouse, the total iron content was also useful for the Blackwater and total calcium for the Great Ouse. It is postulated that this difference is a result of the sediment processes that are known to occur in these two systems, i.e. co-precipitation of phosphate with calcite in the Great Ouse and the formation of vivianite in anoxic sediments of the Blackwater. PMID:11846078

  17. The impact of channel deepening and dredging on estuarine sediment concentration

    NASA Astrophysics Data System (ADS)

    van Maren, D. S.; van Kessel, T.; Cronin, K.; Sittoni, L.

    2015-03-01

    Many estuaries worldwide are becoming more urbanised with heavier traffic in the waterways, requiring continuous channel deepening and larger ports, and increasing suspended sediment concentration (SSC). An example of a heavily impacted estuary where SSC levels are rising is the Ems Estuary, located between the Netherlands and Germany. In order to provide larger and larger ships access to three ports and a shipyard, the tidal channels in the Ems Estuary have been substantially deepened by dredging over the past decades. This has led to tidal amplification and hyper concentrated sediment conditions in the upstream tidal river. In the middle and outer reaches of the Ems Estuary, the tidal amplification is limited, and mechanisms responsible for increasing SSC are poorly understood. Most likely, channel and port deepening lead to larger SSC levels because of resulting enhanced siltation rates and therefore an increase in maintenance dredging. Additionally, channel deepening may increase up-estuary suspended sediment transport due to enhanced salinity-induced estuarine circulation. The effect of channel deepening and port construction on SSC levels is investigated using a numerical model of suspended sediment transport forced by tides, waves and salinity. The model satisfactorily reproduces observed water levels, velocity, sediment concentration and port deposition in the estuary, and therefore is subsequently applied to test the impact of channel deepening, historical dredging strategy and port construction on SSCs in the Estuary. These model scenarios suggest that: (1) channel deepening appears to be a main factor for enhancing the transport of sediments up-estuary, due to increased salinity-driven estuarine circulation; (2) sediment extraction strategies from the ports have a large impact on estuarine SSC; and (3) maintenance dredging and disposal influences the spatial distribution of SSC but has a limited effect on average SSC levels.

  18. Microplastic concentrations in beach sediments along the German Baltic coast.

    PubMed

    Stolte, Andrea; Forster, Stefan; Gerdts, Gunnar; Schubert, Hendrik

    2015-10-15

    The contamination with microplastic particles and fibres was evaluated on beaches along the German Baltic coast. Sediments were sampled near the Warnow and Oder/Peene estuaries, on Rügen island and along the Rostock coast to derive possible entry pathways. Seasonal variations were monitored along the Rostock coast from March to July 2014. After density separation in saline solution, floating particles were found to be dominated by sand grains. Water surface tension is shown to be sufficient to explain floatation of grains with sizes less than 1.5mm. Selecting intensely coloured particles and fibres, we find lower limits of the microplastic concentrations of 0-7 particles/kg and 2-11 fibres/kg dry sediment. The largest microplastic contaminations are measured at the Peene outlet into the Baltic Sea and in the North Sea Jade Bay. City discharges, industrial production sites, fishing activity and tourism are the most likely sources for the highest microplastic concentrations. PMID:26198261

  19. Assessment of sediment toxicity and chemical concentrations in the San Diego Bay region, California, USA

    SciTech Connect

    Fairey, R.; Roberts, C.; Jacobi, M.

    1998-08-01

    Sediment quality within San Diego Bay, Mission Bay, and the Tijuana River Estuary of California was investigated as part of an ongoing statewide monitoring effort (Bay Protection and Toxic Cleanup Program). Study objectives were to determine the incidence, spatial patterns, and spatial extent of toxicity in sediments and porewater; the concentration and distribution of potentially toxic anthropogenic chemicals; and the relationships between toxicity and chemical concentrations. Rhepoxynius abronius survival bioassays, grain size, and total organic carbon analyses were performed on 350 sediment samples. Strongylocentrotus purpuratus development bioassays were performed on 164 pore-water samples. Toxicity was demonstrated throughout the San Diego Bay region, with increased incidence and concordance occurring in areas of industrial and shipping activity. Trace metal and trace synthetic organic analyses were performed on 229 samples. Copper, zinc, mercury, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and chlordane were found to exceed ERM (effects range median) or PEL (probable effects level) sediment quality guidelines and were considered the six major chemicals or chemical groups of concern. Statistical analysis of the relationships between amphipod toxicity, bulk phase sediment chemistry, and physical parameters demonstrated few significant linear relationships. Significant differences in chemical levels were found between toxic and nontoxic responses using multivariate and univariate statistics. Potential sources of anthropogenic chemicals were discussed.

  20. Sediment concentration mapping in tidal estuaries. [Southeastern United States

    NASA Technical Reports Server (NTRS)

    Williamson, A. N.; Grabau, W. E.

    1974-01-01

    An analytical procedure has been developed that considers the ERTS-1 multispectral scanner as a reflectance spectrophotometer. ADP techniques requiring only very limited computer capability are utilized to search the data defining the spectral reflectance characteristics of a scene on a pixel-by-pixel basis, identify each pixel whose spectral reflectance matches a reference spectrum, and generate maps that identify pixel locations where spectrum matches occur and identify the spectrum that was matched. If the reference spectra are known to represent a specific condition on the ground, a map of the distribution of that condition can be output as a dimensionally accurate overlay to maps of any selected scale. Two applications are described: (1) mapping the distribution of water masses exhibiting specific suspended sediment concentrations; and (2) determining the location and delineation of surface water bodies in the southeastern U. S. The techniques described are being successfully used to map the land area inundated by the 1973 spring flood in the Lower Mississippi River Valley, map sediment distributions in Lake Pontchartrain (in Louisiana) as a result of opening the Bonnet Carre Floodway during the spring flood, and inventory lakes and reservoirs.

  1. Estimating suspended sediment concentrations in surface waters of the Amazon River wetlands from Landsat images

    SciTech Connect

    Mertes, L.A.K.; Smith, M.O.; Adams, J.B. )

    1993-03-01

    A method has been developed, based on spectral mixture analysis, to estimate the concentration of suspended sediment in surface waters of the Amazon River wetlands from Landsat MSS and TM images. Endmembers were derived from laboratory reflectance measurements of water-sediment mixtures with a range of sediment concentrations. Using these references spectra, the authors applied a linear mixture analysis to multispectral images after accounting for instrument and atmosphere gains and offsets. Sediment concentrations were estimated for individual pixels from the mixture analysis results based on a nonlinear calibration curve relating laboratory sediment concentrations and reflectance to endmember fractions. The uncertainty in the sediment concentrations derived from this analysis for three Amazon images is predicted to be within [plus minus] 20 mg/L, and the concentrations fall within a range of concentrations of suspended sediment that were measured at several times and places in the field over the past 15 years. The emphasis of their work is to use the patterns of sediment concentrations to compute the approximate volumes of sediment that are transferred between the main channel and floodplain of the Amazon River. However, the methodology can be applied universally if the optical properties of water and sediment at the site are known, and it is, therefore, useful for the study of suspended sediment concentrations in surface waters of wetlands elsewhere.

  2. EVALUATION OF A FLUOROMETRIC SCREENING METHOD FOR PREDICTING TOTAL PAH CONCENTRATIONS IN CONTAMINATED SEDIMENTS

    EPA Science Inventory

    A flurorometric screening method was used to estimate total polycyclic aromatic hydrocarbon concentrations in sediments collected from the St. Louis River Area of Concern in northeastern Minnesota. Sediments were collected as part of a Regional Environmental Monitoring and Asses...

  3. Influence of acid volatile sulfides and metal concentrations on metal partitioning in contaminated sediments

    USGS Publications Warehouse

    Lee, J.-S.; Lee, B.-G.; Luoma, S.N.; Choi, H.J.; Koh, C.-H.; Brown, C.L.

    2000-01-01

    The influence of acid volatile sulfide (AVS) on the partitioning of Cd, Ni, and Zn in porewater (PW) and sediment as reactive metals (SEM, simultaneously extracted metals) was investigated in laboratory microcosms. Two spiking procedures were compared, and the effects of vertical geochemical gradients and infaunal activity were evaluated. Sediments were spiked with a Cd-Ni-Zn mixture (0.06, 3, 7.5 ??mol/g, respectively) containing four levels of AVS (0.5, 7.5, 15, 35 ??mol/g). The results were compared to sediments spiked with four levels of Cd-Ni-Zn mixtures at one AVS concentration (7.5 ??mol/g). A vertical redox gradient was generated in each treatment by an 18-d incubation with an oxidized water column. [AVS] in the surface sediments decreased by 65-95% due to oxidation during incubation; initial [AVS] was maintained at 0.5-7.5 cm depth. PW metal concentrations were correlated with [SEM - AVS] among all data. But PW metal concentrations were variable, causing the distribution coefficient, Kd(pw) (the ratio of [SEM] to PW metal concentrations) to vary by 2-3 orders of magnitude at a given [SEM - AVS]. One reason for the variability was that vertical profiles in PW metal concentrations appeared to be influenced by diffusion as well as [SEM - AVS]. The presence of animals appeared to enhance the diffusion of at least Zn. The generalization that PW metal concentrations are controlled by [SEM - AVS] is subject to some important qualifications if vertical gradients are complicated, metal concentrations vary, or equilibration times differ.The influence of acid volatile sulfide (AVS) on the partitioning of Cd, Ni, and Zn in porewater (PW) and sediment as reactive metals (SEM, simultaneously extracted metals) was investigated in laboratory microcosms. Two spiking procedures were compared, and the effects of vertical geochemical gradients and infaunal activity were evaluated. Sediments were spiked with a Cd-Ni-Zn mixture (0.06, 3, 7.5 ??mol/g, respectively) containing

  4. Influence of mineralogical and heavy metal composition on natural radionuclide concentrations in the river sediments.

    PubMed

    Suresh, G; Ramasamy, V; Meenakshisundaram, V; Venkatachalapathy, R; Ponnusamy, V

    2011-10-01

    The natural radiation level has been determined for the sediment samples of the Ponnaiyar River with an aim of evaluating the radiation hazard. The mineralogical characterizations of the sediments have been carried out using the Fourier Transform Infrared (FTIR) spectroscopic technique. The relative distribution of major minerals is determined by calculating extinction coefficient. The concentration and spatial distribution of heavy metals (Pb, Cr, Cu, Zn and Ni) have been studied to understand the heavy metal contamination and its level of toxicity. To evaluate the potential toxicity, heavy metal concentrations are compared with different toxicological and geological reference values. The comparison results suggest that the present metals create an adverse effect on the aquatic ecosystems associated with this river. To assess the sediment contamination due to the studied heavy metals, the Pollution Load Index (PLI) is calculated. Multivariate Statistical analyses (Pearson Correlation, Cluster and Factor analysis) were carried out between the parameters obtained from radioactivity, mineralogical and geochemical analysis to know the existing relations. Obtained results showed that the effect of mineralogy on level of radioactivity should be significant. However, mineralogy effect on heavy metal composition in the sediments should be limited, indicating that other factors such as vicinity of the pollution sources are more important. Also, the influence of mineralogical characterization on level of radioactivity is significant, whereas the influence of the heavy metal composition on level of radioactivity should be limited. PMID:21636283

  5. Effects of lead-contaminated sediment on Rana sphenocephala tadpoles

    USGS Publications Warehouse

    Sparling, D.W.; Krest, S.K.; Ortiz-Santaliestra, M.

    2006-01-01

    We exposed larval southern leopard frogs (Rana sphenocephala) to lead-contaminated sediments to determine the lethal and sublethal effects of this metal. Tadpoles were laboratory-raised from early free-swimming stage through metamorphosis at lead concentrations of 45, 75, 180, 540, 2360, 3940, 5520, and 7580 mg/kg dry weight in sediment. Corresponding pore water lead concentrations were 123, 227, 589, 1833, 8121, 13,579, 19,038, and 24,427 ug/L. Tadpoles exposed to lead concentrations in sediment of 3940 mg/kg or higher died within 2 to 5 days of exposure. At lower concentrations, mortality through metamorphosis ranged from 3.5% at 45 mg/kg lead to 37% at 2360 mg/kg lead in sediment. The LC50 value for lead in sediment was 3728 mg/kg (95% CI=1315 to 72,847 mg/kg), which corresponded to 12,539 ug/L lead in pore water (95% CI= 4000 to 35,200 ug/L). Early growth and development were depressed at 2,360 mg/kg lead in sediment (8100 ug/L in pore water) but differences were not evident by the time of metamorphosis. The most obvious effect of lead was its pronounced influence on skeletal development. Whereas tadpoles at 45 mg/kg lead in sediment did not display permanent abnormalities, skeletal malformations increased in frequency and severity at all higher lead concentrations. By 2360 mg/kg, 100% of surviving metamorphs displayed severe spinal problems, reduced femur and humerus lengths, deformed digits, and other bone malformations. Lead concentrations in tissues correlated positively with sediment and pore water concentrations.

  6. Concentration, distribution, and bioavailability of mercury and methylmercury in sediments of Baltimore Harbor and Chesapeake Bay, Maryland, USA

    SciTech Connect

    Mason, R.P.; Lawrence, A.L.

    1999-11-01

    For the Chesapeake Bay, sediments in regions such as Baltimore Harbor have total mercury (Hg) concentrations that exceed environmental effects guidelines. However, fish concentrations do not appear elevated. Indeed, the factors controlling the transfer of sedimentary Hg, especially as monomethylmercury (MMHg), the most bioaccumulative form of Hg, to these aquatic organisms are poorly understood. To examine this, the authors have investigated the distribution and bioavailability of Hg and MMHg to benthic organisms in Baltimore harbor and the Chesapeake Bay, in Maryland, USA. The results discussed here show that sediment concentration for both total Hg and MMHg covaries with sediment organic content and that this parameter is a better predictor, for surface sediments, of concentration than iron content, acid volatile sulfide (AVS), or other factors. Furthermore, correlations between inorganic Hg and MMHg in benthic biota with sediment levels suggest that variation in the bioaccumulation factor (SBAF) for invertebrates is best explained in terms of sediment organic content. thus, the results from this study emphasize the importance of organic matter in regions removed from point source input in controlling both the concentration and bioavailability of MMHg to organisms. Because of the exponential nature of the SBAF/organic content relationship, there is a nonlinear organism response to MMHg in sediments that must be considered in any estimation of the toxic effect of sediment MMHg. Also, as a result of the decoupling between total Hg and MMHg concentration and bioavailability in surface sediments, any remediation evaluation of bioavailability and/or toxicity that is based only on total Hg concentration is unlikely to provide a reliable prediction.

  7. 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.

  8. Associations between female reproductive traits and polychlorinated biphenyl sediment concentrations in wild populations of brown bullhead (Ameiurus nebulosus).

    PubMed

    Farwell, Michelle; Drouillard, Ken G; Heath, Daniel D; Pitcher, Trevor E

    2013-11-01

    Aquatic contaminants, specifically polychlorinated biphenyls (PCBs), a class of persistent organic contaminants, have been associated with sublethal effects on reproduction in fishes. Female brown bullhead (Ameiurus nebulosus) were used to assess variation in reproductive traits across eight populations differing in sediment sum PCB concentrations in the Lower Great Lakes region. Differences in maternal carotenoid allocation patterns among these populations were also examined. No significant associations were found between sediment sum PCB concentrations corrected for organic content (OC) and reproductive traits. However, egg diameter was negatively correlated with sediment PCB concentrations not corrected for OC, suggesting that observed relationships between sediment sum PCB concentrations and reproductive traits are driven by classes of environmental contaminants whose bioavailability are not predicted by OC, such as metals. An unexpected positive relationship was also found between egg carotenoid concentrations and sediment PCB concentrations. This positive relationship was explained by the maternal allocation of carotenoids based on a negative correlation between female muscle and egg carotenoid concentrations, where females from less contaminated locations had lower egg and greater muscle carotenoid concentrations than those from more contaminated locations. The results of this study identify sublethal effects of environmental contaminants on reproductive life-history traits in female brown bullhead, and investigations of adaptive mechanisms underlying this variation are warranted. PMID:23887386

  9. Steep wave, turbulence, and sediment concentration statistics beneath a breaking wave field and their implications for sediment transport

    NASA Astrophysics Data System (ADS)

    Scott, Nicholas V.; Hsu, Tian-Jian; Cox, Daniel

    2009-11-01

    A new methodology based on wavelet analysis is used to estimate steep wave statistics under depth-limited conditions and the corresponding high concentration sediment statistics. Steep waves here are defined as wave crests within the wavelet transform exceeding a root mean square derived acceleration threshold. The method is applied to laboratory data obtained in a large-scale wave-flume experiment conducted in 2005 at Oregon State University's O. H. Hinsdale Wave Research Laboratory from an acoustic Doppler velocimeter and a fiber optic backscatter sensor array above a mobile sand bed. The steep wave and high concentration statistical results for the erosive condition suggest that sand suspensions are intermittent when a wave-breaking timescale (the ratio of breaking wave height and rms wave velocity) is used to detect the concurrence among steep wave, high velocity turbulent fluctuations, and sand concentration events near the bed. More importantly, at 1 cm above the bed, though the accretive case has more steep wave events, the erosive case has more steep waves and concurrent high concentration events, suggesting a more intense breaking wave process near the sensors. The use of a longer time window, based on the dominant wave period in the detection process of steep wave and high concentration events at 1 cm above the bed, does not change the resulting statistics for the erosive condition. However, increased percentages of high concentration events correlated with steep wave and high velocity turbulence events for the accretive condition are obtained. These increased percentages are conjectured to be due to advection of non-local turbulent events and sediment concentration peaks from upstream. A one-dimensional vertical two-phase model for sand transport is modified here to take measured breaking wave turbulence quantities as top boundary conditions to simulate the effect of breaking wave-turbulence on bottom sediment transport. Model results suggest that high

  10. Summary of Suspended-Sediment Concentration Data, San Francisco Bay, California, Water Year 2007

    USGS Publications Warehouse

    Buchanan, Paul A.; Morgan, Tara L.

    2010-01-01

    Suspended-sediment concentration data were collected by the U.S. Geological Survey in San Francisco Bay during water year 2007 (October 1, 2006-September 30, 2007). Optical sensors and water samples were used to monitor suspended-sediment concentration at two sites in Suisun Bay, two sites in Central San Francisco Bay, and one site in South San Francisco Bay. Sensors were positioned at two depths at most sites to help define the vertical variability of suspended sediments.Water samples were collected periodically and analyzed for concentrations of suspended sediment. The results of the analyses were used to calibrate the output of the optical sensors so that a record of suspended-sediment concentrations could be derived. This report presents the data-collection methods used and summarizes, in graphs, the suspended-sediment concentration data collected from October 2006 through September 2007. Calibration curves and plots of the processed data for each sensor also are presented.

  11. Summary of suspended-sediment concentration data, San Francisco Bay, California, water year 2008

    USGS Publications Warehouse

    Buchanan, Paul A.; Morgan, Tara L.

    2011-01-01

    Suspended-sediment concentration data were collected by the U.S. Geological Survey in San Francisco Bay during water year 2008 (October 1, 2007–September 30, 2008). Optical sensors and water samples were used to monitor suspended-sediment concentration at two sites in Suisun Bay, two sites in Central San Francisco Bay, and one site in South San Francisco Bay. Sensors were positioned at two depths at most sites to help define the vertical variability of suspended sediments. Water samples were collected periodically and analyzed for concentrations of suspended sediment. The results of the analyses were used to calibrate the output of the optical sensors so that a record of suspended-sediment concentrations could be derived. This report presents the data-collection methods used and summarizes, in graphs, the suspended-sediment concentration data collected from October 2007 through September 2008. Calibration curves and plots of the processed data for each sensor also are presented.

  12. Heavy metal concentrations in Louisiana waterways, sediments, and biota

    SciTech Connect

    Bundy, K.J.; Berzins, D.

    1994-12-31

    In this investigation polarographic methods (along with GFAAS and ICP) have been used to study the distribution of lead and chromium in Bayou Trepagnier and Devil`s Swamp. Both laboratory and field research have been conducted. Separation and extraction methodology appropriate for analysis of the contaminants at these sites have been developed. Particular attention has been paid to extraction methods for chromium which do not lead to valence state conversion. The availability of such techniques is essential to take full advantage of polarography, a method capable of performing speciation analysis. The results indicate that there is a very inhomogeneous distribution of heavy metals in these environments. In Devil`s Swamp, for example, separation and analysis of aqueous and variously sized particulate moieties in the water and sediment compartments were conducted to determine the partition of lead between them. The results showed that the average lead content was 14.7 ppb and 19.8 ppm, respectively, in these compartments. Apparently bull frogs in Devil`s Swamp can bioaccumulate lead (compared to the measured water level), since the muscle concentration was found to be about 0.6 ppm. This phenomenon is being investigated in a Xenopus frog laboratory model of heavy metal uptake. The basic methodology validated in this study should be fairly generally applicable to assays of other heavy metals.

  13. Distribution Characteristics, Concentrations, and Sources of Cd and Pb in Laoxiawan Channel Sediments from Zhuzhou, China.

    PubMed

    Chen, Wen-Wen; Zhang, Jian-Xin; Abass, Olusegun-Kazeem; Wen, Xin-Yu; Huang, Huan-Fang; Qu, Cheng-Kai; Qi, Shi-Hua

    2016-06-01

    Twenty sediment cores encompassing surface (0-20 cm) and deeper (50-60 cm) sediment layers were retrieved from the 3000 m-long Laoxiawan Channel, which receives industrial effluents from Zhuzhou City (China). Analytical results showed that cadmium (Cd) concentrations ranged between 115.7-1126.7 and 108.8-2059.3 mg/kg while lead (Pb) values ranged between 234-3000 and 145-4292 mg/kg in the surface and bottom sediments, respectively. The results also indicated that high levels of Cd and Pb were present in the vicinity of the channel mouth and confluence area. Indices for potential ecological risk and geo-accumulation were used to evaluate the environmental effects and intensity of heavy metal pollution over time. High concentrations of Cd and Pb in the bottom sediments of Laoxiawan Channel were mainly associated with wastewater discharge (10(6) m(3)/year). Thus, the Laoxiawan Channel may be an important metal contaminant source for the Xiang River. PMID:27025765

  14. The dependence of bacterial sulfate reduction on sulfate concentration in marine sediments

    NASA Astrophysics Data System (ADS)

    Boudreau, Bernard P.; Westrich, Joseph T.

    1984-12-01

    The effect of dissolved sulfate concentration on the rate of bacterial sulfate reduction in marine sediment from Long Island Sound was examined using a radio-sulfur technique. The experimental results show that the rate is independent of the dissolved sulfate concentration until low levels are reached (<3 mM), and that, when interpreted using a Monod-type rate law, a saturation constant, Ks, of 1.62 ± 0.16 M results. This weak dependence implies that the dissolved sulfate exerts only a limited influence on the rate of sulfate reduction in marine sediments. Given such a weak dependence, dissolved sulfate profiles in marine sediments must resemble profiles generated by models with sulfate independent kinetics. Initially, this would suggest that currently used sulfate-independent diagenetic models are appropriate in modelling sulfate profiles. However, comparison of these models with those containing weak sulfate-dependent kinetic terms shows that there exists considerable disagreement between these models when the parameter grouping (D sk) 1/2/w is larger than ~0.2 and smaller than ~3.0. (Here Ds is the SO ; 4 diffusion coefficient, k the organic matter decay constant and w the sediment burial velocity.) When the currently used models are corrected by employing physically meaningful boundary conditions, this divergence disappears. The modelling results, therefore, confirm the conclusion that any sulfate dependence inherent to the reduction kinetics does not appreciably affect sulfate pore water profiles, and that previous diagenetic studies using strong sulfate dependent models are erroneous.

  15. High concentration suspended sediment measurments using acontinuous fiber optic in-stream transmissometer

    SciTech Connect

    Campbell, Chris G.; Laycak, Danny T.; Hoppes, William; Tran,Nguyen T.; Shi, Frank G.

    2004-05-26

    Suspended sediment loads mobilized during high flow periods in rivers and streams are largely uncharacterized. In smaller and intermittent streams, a large storm may transport a majority of the annual sediment budget. Therefore monitoring techniques that can measure high suspended sediment concentrations at semi-continuous time intervals are needed. A Fiber optic In-stream Transmissometer (FIT) is presented for continuous measurement of high concentration suspended sediment in storm runoff. FIT performance and precision were demonstrated to be reasonably good for suspended sediment concentrations up to 10g/L. The FIT was compared to two commercially available turbidity devices and provided better precision and accuracy at both high and low concentrations. Both turbidity devices were unable to collect measurements at concentrations greater than 4 g/L. The FIT and turbidity measurements were sensitive to sediment particle size. Particle size dependence of transmittance and turbidity measurement poses the greatest problem for calibration to suspended sediment concentration. While the FIT was demonstrated to provide acceptable measurements of high suspended sediment concentrations, approaches to real-time suspended sediment detection need to address the particle size dependence in concentration measurements.

  16. Sediment concentration profiles in bed-near-bed layers under unsteady flow and sediment conditions : a CT-Scanned flume investigation

    NASA Astrophysics Data System (ADS)

    Leclair, Suzanne; Long, Bernard

    2015-04-01

    This paper presents a case study from a CT-scan flume experiment on the variation in sediment transport (concentration) under transitional, initially high-regime (but decreasing), sub-critical flow with bed erosion or no net aggradation. The objective is to better understand sediment transport during unsteady flows such as during a wining flood. In particular, the effect of mud-aggregate transport on sediment concentration in the bed-near-bed continuum was addressed. CT-scans were taken during sediment transport, with plane beds or dunes being the bed state. The density material (water and/or sediment) in over 105 volumes (voxels, each approximately equivalent to a grain of 0.8 mm) were analysed. Computed Tomography technology provides high-resolution results, both in time and space, and allows recognition of subtle changes in the shape of relative sediment concentration profile with bed states. The migration and attrition of mud aggregates in this experiment increased the mean volume fraction sediment concentration in the bed-near-bed layer (lower 5% of the flow) by a factor of about 2, from an inital value of 0.12 up to 0.25, and back to 0.13 when the supply ended. Also, the presence of mud-aggregates in the preserved deposits (transported as bedload) increases bed porosity. This case study demonstrates the great potential of Computed Tomography in process-oriented, experimental sedimentology. The community would benefit from more collaborative research using this technology, including data sharing as suggested by initiatives such as the Sediment Experimentalists Network (http://workspace.earthcube.org/sen)

  17. Suspended sediment concentration - discharge relationships in the (sub) humid Ethiopian highlands

    NASA Astrophysics Data System (ADS)

    Guzman, C. D.; Tilahun, S. A.; Zegeye, A. D.; Steenhuis, T. S.

    2012-07-01

    Loss of top soil and subsequent filling up of reservoirs in much of the lands with variable relief in developing countries degrades environmental resources necessary for subsistence. In the Ethiopia highlands, sediment mobilization from rain-fed agricultural fields is one of the leading factors causing land degradation. Sediment rating curves, produced from long-term sediment concentration and discharge data, attempt to predict suspended sediment concentration variations that exhibit a distinct shift with the progression of the rainy season. In this paper, we calculate sediment rating curves and examine this shift in concentration for three watersheds in which rain-fed agriculture is practiced to differing extents. High sediment concentrations with low flows are found in the beginning of the rainy season of the semi-monsoonal climate, while high flows and low sediment concentrations occur at the end of the rainy season. Results show that a reasonable unique set of rating curves were obtained by separating biweekly data into early, mid, and late rainfall periods and by making adjustments for the ratio of plowed cropland. The shift from high to low concentrations suggests that diminishing sediment supply and dilution from greater base flow during the end of the rainfall period play important roles in characterizing changing sediment concentrations during the rainy season.

  18. Suspended sediment concentration-discharge relationships in the (sub-) humid Ethiopian highlands

    NASA Astrophysics Data System (ADS)

    Guzman, C. D.; Tilahun, S. A.; Zegeye, A. D.; Steenhuis, T. S.

    2013-03-01

    Loss of top soil and subsequent filling up of reservoirs in much of the lands with variable relief in developing countries degrades environmental resources necessary for subsistence. In the Ethiopia highlands, sediment mobilization from rain-fed agricultural fields is one of the leading factors causing land degradation. Sediment rating curves, produced from long-term sediment concentration and discharge data, attempt to predict suspended sediment concentration variations, which exhibit a distinct shift with the progression of the rainy season. In this paper, we calculate sediment rating curves and examine this shift in concentration for three watersheds in which rain-fed agriculture is practiced to differing extents. High sediment concentrations with low flows are found at the beginning of the rainy season of the semi-monsoonal climate, while high flows and low sediment concentrations occur at the end of the rainy season. Results show that a reasonably unique set of rating curves were obtained by separating biweekly data into early, mid, and late rainfall periods and by making adjustments for the ratio of plowed cropland. The shift from high to low concentrations suggests that diminishing sediment supply and dilution from greater base flow during the end of the rainfall period play important roles in characterizing changing sediment concentrations during the rainy season.

  19. Tracking Metal Pollution in Lake Chapala: Concentrations in Water, Sediments, and Fish.

    PubMed

    Torres, Zaria; Mora, Miguel A; Taylor, Robert J; Alvarez-Bernal, Dioselina

    2016-09-01

    We measured concentrations of selected metals (Al, Ba, Cu, Mn, Hg, Sr, V, and Zn) in water, sediments, and fish from Lake Chapala and a reference site to evaluate potential negative effects on wildlife, particularly fish-eating birds. Fish metal concentrations ranged from 0.05 µg/g wet weight (ww) for Al and Cu to 64.70 µg/g ww for Sr. There was a positive and significant correlation between fish length and metals particularly for Ba, Cu, Mn, and Zn in Lake Chapala (p < 0.05). However, there were no significant correlations between metal concentrations and δ(15)N values in fish indicating no biomagnification through the food web. Overall, metal concentrations in water, sediments, and fish were similar to and in some cases below those reported for Lake Chapala over the last 20 years. Also, metal concentrations were below those that could be of concern for negative effects on fish and wildlife of Lake Chapala. PMID:27460823

  20. Shallow Sediment Trace Metal Concentrations and Short-Term Accumulation Rates in the Neponset River Estuary, Massachusetts, USA

    NASA Astrophysics Data System (ADS)

    Spencer, J. R.; Zhu, J.; Olsen, C. R.

    2010-12-01

    The Neponset River estuary is a small estuary that drains into the Boston Harbor on the east coast of the United States. It is also a highly urbanized estuary and has a long history of urban development over 450 years. In July 2006, six sediment cores were collected in the Neponset River estuary to examine particle dynamics and sediment accumulation via radionuclide (Beryllium-7) dating, and to determine sediment metal concentrations (As, Cu, Pb, and Zn) via ED-XRF measurements. Measured sediment Be-7 profiles indicate various sedimentation environments, where sediment accumulation, resuspension or redeposition is likely to occur. High metal concentrations were often corresponding to high Be-7 inventories in sediment cores. Possible sources of trace metal contaminants in the water column include: storm water run-off, Combined Sewer Overflows (CSOs), a well-documented industrial pollution event that occurred upstream in the early to mid twentieth century, and the resuspension of sediment. Existing and future data will provide baseline information for quantifying the effects of the proposed and pending environmental restoration project, which includes the removal of the Baker Dam. The combined pre- and post-Dam removal data may then be used in cost-benefit analyses for other similar estuarine restoration projects.

  1. Responses in sediment phosphorus and lanthanum concentrations and composition across 10 lakes following applications of lanthanum modified bentonite.

    PubMed

    Dithmer, Line; Nielsen, Ulla Gro; Lürling, Miquel; Spears, Bryan M; Yasseri, Said; Lundberg, Daniel; Moore, Alanna; Jensen, Nicholai D; Reitzel, Kasper

    2016-06-15

    A combined field and laboratory scale study of 10 European lakes treated between 2006 and 2013 with a lanthanum (La) modified bentonite (LMB) to control sediment phosphorus (P) release was conducted. The study followed the responses in sediment characteristics including La and P fractions and binding forms, P adsorption capacity of discrete sediment layers, and pore water P concentrations. Lanthanum phosphate mineral phases were confirmed by solid state (31)P MAS NMR and LIII EXAFS spectroscopy. Rhabdophane (LaPO4 · nH2O) was the major phase although indications of monazite (LaPO4) formation were also reported, in the earliest treated lake. Molar ratios between La and P in the sediments were generally above 1, demonstrating excess La relative to P. Lanthanum was vertically mixed in the sediment down to a depth of 10 cm for eight of the ten lakes, and recovery of La in excess of 100% of the theoretical aerial load indicated translocation of the LMB towards the deepest areas of the lakes. Lanthanum was generally recovered from bed sediment samples following sequential chemical extraction from the HCl fraction. Soluble reactive P (SRP) release experiments on intact sediment cores indicated conditions of P retention (with the exception of two lakes) by sediments, indicating effective control of sediment P release, i.e. between two and nine years after treatment. PMID:26971297

  2. Summary of Suspended-Sediment Concentration Data, San Francisco Bay, California, Water Year 2005

    USGS Publications Warehouse

    Buchanan, Paul A.; Lionberger, Megan A.

    2007-01-01

    Suspended-sediment concentration data were collected by the U.S. Geological Survey in San Francisco Bay during water year 2005 (October 1, 2004-September 30, 2005). Optical sensors and water samples were used to monitor suspended-sediment concentration at two sites in Suisun Bay, three sites in San Pablo Bay, two sites in Central San Francisco Bay, and three sites in South San Francisco Bay. Sensors were positioned at two depths at most sites. Water samples were collected periodically and analyzed for concentrations of suspended sediment. The results of the analyses were used to calibrate the output of the optical sensors so that a record of suspended-sediment concentrations could be derived. This report presents the data-collection methods used and summarizes, in graphs, the suspended-sediment concentration data collected from October 2004 through September 2005. Calibration curves and plots of the processed data for each sensor also are presented.

  3. The Use of Measured Suspended Sediment Concentrations at Alcatraz to Infer Net Suspended Sediment Transport at the Golden Gate

    NASA Astrophysics Data System (ADS)

    Erikson, L. H.; Wright, S. A.; Elias, E.; Hanes, D. M.; Schoellhamer, D. H.

    2012-12-01

    Numerical model simulations combined with physical measurements were used to estimate the net volumetric water and suspended sediment flux at teh Golden Gate between San Francisco Bay and the coastal ocean. Measurements were obtained using vessel-mounted acoustic Doppler current profilers and semi-empirical calibrations between backscatter intensity and in situ suspended-sediment concentrations throughout the water column. Transects across the inlet were repeated continuously for >12 h during both spring and neap tides to provide near-synoptic measurements over full tidal cycles. A numerical model was validated against volumetric water flux and calibrated against sediment flux measurements which were then used to estimate net sediment exchange. The product of current vectors computed with a numerical model and synoptic measurements of suspended- sediment concentrations at the nearby continuous monitoring site on Alcatraz Island showed reasonable correlation with tide-averaged sediment flux through the Gate; this provided a basis for the development of an analytical relationship to estimate suspended sediment flux through the Golden Gate using continuous measurements at Alcatraz as a proxy.

  4. Aerobic Biofilms Grown from Athabasca Watershed Sediments Are Inhibited by Increasing Concentrations of Bituminous Compounds

    PubMed Central

    Lawrence, John R.; Sanschagrin, Sylvie; Roy, Julie L.; Swerhone, George D. W.; Korber, Darren R.; Greer, Charles W.

    2013-01-01

    Sediments from the Athabasca River and its tributaries naturally contain bitumen at various concentrations, but the impacts of this variation on the ecology of the river are unknown. Here, we used controlled rotating biofilm reactors in which we recirculated diluted sediments containing various concentrations of bituminous compounds taken from the Athabasca River and three tributaries. Biofilms exposed to sediments having low and high concentrations of bituminous compounds were compared. The latter were 29% thinner, had a different extracellular polysaccharide composition, 67% less bacterial biomass per μm2, 68% less cyanobacterial biomass per μm2, 64% less algal biomass per μm2, 13% fewer protozoa per cm2, were 21% less productive, and had a 33% reduced content in chlorophyll a per mm2 and a 20% reduction in the expression of photosynthetic genes, but they had a 23% increase in the expression of aromatic hydrocarbon degradation genes. Within the Bacteria, differences in community composition were also observed, with relatively more Alphaproteobacteria and Betaproteobacteria and less Cyanobacteria, Bacteroidetes, and Firmicutes in biofilms exposed to high concentrations of bituminous compounds. Altogether, our results suggest that biofilms that develop in the presence of higher concentrations of bituminous compounds are less productive and have lower biomass, linked to a decrease in the activities and abundance of photosynthetic organisms likely due to inhibitory effects. However, within this general inhibition, some specific microbial taxa and functional genes are stimulated because they are less sensitive to the inhibitory effects of bituminous compounds or can degrade and utilize some bitumen-associated compounds. PMID:24056457

  5. Sediment concentrations of trace metals in the Berre lagoon (France): an assessment of contamination.

    PubMed

    Accornero, Alessandra; Gnerre, Rossella; Manfra, Loredana

    2008-04-01

    This paper reports the concentrations of eight trace metals (Cr, Zn, Cu, Pb, Ni, As, Cd, and Hg) in the surficial sediments of the Berre lagoon. This is a typical Mediterranean lagoon, seriously affected by human activities since the 1930s, when it became one of the most important industrial sites in France. The overall range of concentrations is 38-428 mg kg(-1) for chromium, 50-151 mg kg(-1) for zinc, 11-48 mg kg(-1) for copper, 18-82 mg kg(-1) for lead, 18-56 mg kg(-1) for nickel, 4-10 mg kg(-1) for arsenic, 0.2-1.6 mg kg(-1) for cadmium, and 0.15-0.40 mg kg(-1) for mercury. The spatial distribution of concentrations largely mirrors the localization of major impact sources, with the most affected area restricted to a radius of a few kilometers from point sources, due to the environmental conditions of the outfall zone (fine sediments, low hydrodynamic regime, confinement), which favor the in situ accumulation of pollutants. The extent of contamination from trace metals in the lagoon sediments is evaluated through a three-pronged approach: (i) by comparison with other areas (see Table 3 for an up-to-date review of trace metal concentrations in lagoon systems and coastal regions of the world ocean); (ii) by evaluating the metal enrichment in the sediments through the calculation of concentration factors (CF) for each trace metal and by combining the CFs to estimate a Metal Pollution Index (MPI) taking into account the differences in toxicity of trace metals; and (iii) by defining a potential level of biological risk by the use of quality criteria such as the Threshold Effect Level (TEL) and Effects Range-Low (ER-L) benchmarks. On the basis of the calculated CFs, sediments appear as particularly enriched with Pb and Cd throughout the lagoon and with Cr and Zn at some sites. Although no site can be classified as "unpolluted" when looking at the calculated MPIs, two regions--the Vaïne pond and the southwestern area--have been identified as critical points of

  6. Concentration and Spatial Distribution of Selected Constituents in Detroit River Bed Sediment Adjacent to Grassy Island, Michigan, August 2006

    USGS Publications Warehouse

    Hoard, C.J.

    2008-01-01

    In August 2006, the U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service, collected sediment?core samples from the bed of the Detroit River adjacent to Grassy Island. The goal of the sampling was to assess the distribution and concentration of chemical constituents in sediment adjacent to Grassy Island, which was operated from 1960 to 1982 as a confined disposal facility to hold dredge spoils. On August 31, 2006, seven samples were collected at four locations in the Detroit River on the north, south, east, and west sides of the island. Metals concentrations in the riverbed sediment tended to be higher on the west side of the island, whereas organic?compound concentrations were generally higher on the east side. Comparison of results from this sampling to concentrations reported in previous studies indicates that the concentrations of inorganic constituents, mainly metals, in the riverbed sediment around Grassy Island fell within the range of concentrations found regionally throughout the Detroit River and in most cases have lower mean and median values than found elsewhere regionally in the Detroit River. Comparison of results from the August 31, 2006, sampling to U.S. Environmental Protection Agency risk?based sediment?quality guidelines indicates that 18 organic constituents for which an ecological screening level (ESL), and (or) a threshold effect concentration (TEC), and (or) a probable effect concentration (PEC) has been defined exceeded one or more of these guidelines at least once. Further work would be needed to determine whether constituent concentrations in the river sediment are related to constituent runoff from Grassy Island.

  7. Metals concentrations in sediments and oyster Crassostrea gigas from La Pitahaya lagoon, Sinaloa, NW Mexico

    NASA Astrophysics Data System (ADS)

    Luna Varela, R.; Muñoz Sevilla, N.; Campos Villegas, L.; Rodriguez Espinosa, P.; Gongora Gomez, A.; MP, J.

    2013-05-01

    This present study was performed in a culture of Crassostrea gigas in La Pitahaya, Sinaloa, México. The main objective is to identify the enrichment pattern of trace elements (Cu, Cd, Cr, Ni, Pb, Zn, Hg, As, V) also was determine concentrations thereof in oyster. Four sampling sites were selected, two smaller channels which connect the lagoon directly , the region of culture and connection with the sea ; and each sampling consisted of 4 sample sediments and 50 oysters of commercial size per mounth . Concentrations of trace metals were determined using atomic absorption spectrophotometry (AAS). The higher concentration of elements in certain samples clearly suggests that they are directly fed by the smaller channels which connect the lagoon directly. These small channels often carry the contaminants which are absorbed and deposited in the sediments. The results were also compared with the Effect Range Low (ERL) and Effect Range Medium (ERM) of NOAA and it indicates that Ni is above the ERL values. Cadmium, lead, chrome and copper concentrations exceeded the limits permissible of bivalbe mollusks established by the sanitary regulations

  8. Evaluating suitability of MODIS-Terra images for reproducing historic sediment concentrations in water bodies: Lake Tana, Ethiopia

    NASA Astrophysics Data System (ADS)

    Kaba, Essayas; Philpot, William; Steenhuis, Tammo

    2014-02-01

    Government and NGO funded conservation programs are being implemented in developing countries with the potential benefit of reduced sediment inflow into fresh water lakes. However, these claims are difficult to verify due to limited historical sediment concentration data in lakes and rivers. Remote sensing can potentially aid in monitoring sediment concentration. With almost daily availability over the past ten years and consistent atmospheric correction applied to the images, Moderate Resolution Imaging Spectroradiometer (MODIS) 250 meter images are potential resources capable of monitoring future concentrations and reconstructing historical sediment concentration records. In this paper, site-specific relationships are developed between reflectance in near-infrared (NIR) images and three factors: total suspended solids (TSS), turbidity and Secchi depth for Lake Tana near the mouth of the Gumara River. The first two sampling campaigns on November 27, 2010 and May 13, 2011 are used in calibration. Reflectance in the NIR varies linearly with turbidity (R2 = 0.89) and TSS (R2 = 0.95). Secchi depth fit best to an exponential relation with R2 of 0.74. The relationships are validated using a third sample set collected on November 7, 2011 with RMSE of 11 Nephelometric Turbidity Units (NTU) for Turbidity, 16.5 mg l-1 for TSS and 0.12 meters for Secchi depth. The MAE was 10% for TSS, 14% for turbidity and 0.1% for Secchi depth. Using the relationship for TSS, a 10-year time series of sediment concentration in Lake Tana near the Gumara River was plotted. It was found that after the severe drought of 2002 and 2003 the concentration in the lake increased significantly. The results showed that MODIS images are potential cost effective tools to monitor suspended sediment concentration and obtain a past history of concentration for evaluating the effect of best management practices.

  9. 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.

  10. 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.

  11. Stream Water and Sediment Phosphorus Equilibrium Concentrations in Ozark Streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Little information is broadly available on the fate and transport of dissolved phosphorus (DP) in streams draining agricultural and urban catchments, although in-stream processes might have a substantial influence on downstream transport. This study evaluated sediment-water P equilibrium concentrat...

  12. Sediment carbon concentration and transport from small pastured watersheds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    With the current emphasis on the role of carbon in the environment, agricultural systems and their impacts on the carbon cycle are important parts of the overall issue. Pasture systems and carbon that is transported attached to sediment has been addressed at the North Appalachian Experimental Waters...

  13. Rhizon sampler alteration of deep ocean sediment interstitial water samples, as indicated by chloride concentration and oxygen and hydrogen isotopes

    NASA Astrophysics Data System (ADS)

    Miller, Madeline D.; Adkins, Jess F.; Hodell, David A.

    2014-06-01

    their potential to inform past ocean salinity, δ18O, and temperature, high-resolution depth profiles of interstitial water chloride concentration and hydrogen and oxygen isotopes exist in very few locations. One of the primary limitations to the recovery of these depth profiles is that traditional interstitial water sampling requires 5-10 cm whole rounds of the sediment core, which has the potential to interfere with stratigraphic continuity. The Rhizon sampler, a nondestructive tool developed for terrestrial sediment interstitial water extraction, has been proposed for efficient and nondestructive sampling of ocean sediment pore waters. However, there exists little documentation on the reliability and performance of Rhizon samplers in deep ocean sediments, particularly in regard to their effect on chloride concentration and oxygen and hydrogen isotopic measurements. We perform an intercomparison of chloride concentration and oxygen and hydrogen isotopic composition in samples taken using traditional squeezing versus those taken with Rhizon samplers. We find that samples taken with Rhizons have positive biases in both chloride concentration and stable isotopic ratios relative to those taken by squeezing water from sediments in a hydraulic press. The measured offsets between Rhizon and squeeze samples are consistent with a combination of absorption by and diffusive fractionation through the hydrophilic membrane of the Rhizon sampler. These results suggest caution is needed when using Rhizons for sampling interstitial waters in any research of processes that leave a small signal-to-noise ratio in dissolved concentrations or isotope ratios.

  14. Nearshore bar migration and sediment-induced buoyancy effects

    NASA Astrophysics Data System (ADS)

    Falchetti, Silvia; Conley, Daniel C.; Brocchini, Maurizio; Elgar, Steve

    2010-02-01

    A 1-D General Ocean Turbulence Model that includes the effects of sediment-induced stratification is shown to simulate the observed onshore and offshore migration of a nearshore sandbar. The only two free parameters of the model, the bed reference concentration and the sediment diffusivity, are taken from the literature, rather than tuned to the data used here. The model results suggest that predictions of onshore bar migration, in which wave-induced sediment transport confined to within a few centimeters of the bottom dominates, are not greatly affected by accounting for buoyancy effects. The model results also suggest that both mean flows and waves transport sediment during offshore bar migration, with different components of transport dominating at different cross-shore locations across the bar-trough bathymetry. Neglecting the effects of sediment-induced stratification results in higher model skill during the largest waves, likely because the excess turbulence production simulated by the non-stratified model is counterbalanced by neglected breaking-wave-generated turbulence. Considering both onshore and offshore migration, the model that includes sediment-induced stratification has higher skill than the model without stratification.

  15. Suspended-sediment concentration and pool sedimentation data for the Gibbon River, Yellowstone National Park, Wyoming, September 2000 through October 2001

    USGS Publications Warehouse

    Wright, Peter R.; Zelt, Ronald B.

    2003-01-01

    This report presents data on streamflow, suspended-sediment concentration, geomorphic measurements of pools, and particle-size distribution of surficial bed material, collected along a 5-mile reach of the Gibbon River in Yellowstone National Park. The study was done in cooperation with the National Park Service. The Park Service was concerned about the potential effects that road reconstruction would have on water quality. A streamflow-gaging station and two automatic pumping samplers were installed in September 2000 to collect suspended-sediment samples. The gage and samplers were operated seasonally from March through September 2001. The geomorphic survey of pools and sampling of bed material occurred during October 2000.

  16. REVIEW OF HISTORICAL AND RECENT MERCURY CONCENTRATIONS IN GREAT LAKES SEDIMENTS

    EPA Science Inventory

    Sediments of the Great Lakes have been impacted by inputs of mercury to the lakes. The first measurements of mercury concentrations in Great Lakes sediments were for samples collected in 1968 for Lake Ontario, 1969 for Lake Huron, 1969-70 for Lake Michigan, 1970 for Lake St. Cl...

  17. Spatial Evaluation of Heavy Metals Concentrations in the Surface Sediment of Taihu Lake.

    PubMed

    Niu, Yong; Jiao, Wei; Yu, Hui; Niu, Yuan; Pang, Yong; Xu, Xiangyang; Guo, Xiaochun

    2015-12-01

    With regard to the size of China's freshwater lakes, Taihu Lake ranks third and it plays an important role in the supply of drinking water, flood prevention, farming and navigation, as well as in the travelling industry. The problem of environmental pollution has attracted widespread attention in recent years. In order to understand the levels, distribution and sources of heavy metals in sediments of Taihu Lake, random selection was carried out to obtain 59 samples of surface sediment from the entire lake and study the concentrations of Pb, Cd, Cu, Zn, Cr and Ni. Toxic units were also calculated to normalize the toxicities caused by various heavy metals. As a result, Cd and Cu in sediment were considered lower than the effect range low (ERL) at all regions where samples were gathered, while Pb and Ni were categorized into ERL-effect range median (ERM) at over 22% of the regions where samples were obtained. Nevertheless, all average concentrations of the samples were below the level of potential effect. According to the findings of this research, significant spatial heterogeneity existed in the above heavy metals. In conclusion, the distribution areas of heavy metals with higher concentrations were mainly the north bays, namely Zhushan Bay, Meiliang Bay as well as Gonghu Bay. The distribution areas of Cu, Zn, Cr and Ni with higher concentration also included the lake's central region, whereas the uniform distribution areas of those with lower concentrations were the lake's southeast region. In addition, it was most probable that the spatial distribution of heavy metals was determined by river inputs, whereas atmospheric precipitation caused by urban and traffic contamination also exerted considerable effects on the higher concentrations of Pb and Cd. Through evaluating the total amount of toxic units (ΣTU), it was found that higher toxicity existed primarily in the north bays and central region of the lake. If the heavy metals were sorted by the reduction of mean

  18. Spatial Evaluation of Heavy Metals Concentrations in the Surface Sediment of Taihu Lake

    PubMed Central

    Niu, Yong; Jiao, Wei; Yu, Hui; Niu, Yuan; Pang, Yong; Xu, Xiangyang; Guo, Xiaochun

    2015-01-01

    With regard to the size of China’s freshwater lakes, Taihu Lake ranks third and it plays an important role in the supply of drinking water, flood prevention, farming and navigation, as well as in the travelling industry. The problem of environmental pollution has attracted widespread attention in recent years. In order to understand the levels, distribution and sources of heavy metals in sediments of Taihu Lake, random selection was carried out to obtain 59 samples of surface sediment from the entire lake and study the concentrations of Pb, Cd, Cu, Zn, Cr and Ni. Toxic units were also calculated to normalize the toxicities caused by various heavy metals. As a result, Cd and Cu in sediment were considered lower than the effect range low (ERL) at all regions where samples were gathered, while Pb and Ni were categorized into ERL-effect range median (ERM) at over 22% of the regions where samples were obtained. Nevertheless, all average concentrations of the samples were below the level of potential effect. According to the findings of this research, significant spatial heterogeneity existed in the above heavy metals. In conclusion, the distribution areas of heavy metals with higher concentrations were mainly the north bays, namely Zhushan Bay, Meiliang Bay as well as Gonghu Bay. The distribution areas of Cu, Zn, Cr and Ni with higher concentration also included the lake’s central region, whereas the uniform distribution areas of those with lower concentrations were the lake’s southeast region. In addition, it was most probable that the spatial distribution of heavy metals was determined by river inputs, whereas atmospheric precipitation caused by urban and traffic contamination also exerted considerable effects on the higher concentrations of Pb and Cd. Through evaluating the total amount of toxic units (ΣTU), it was found that higher toxicity existed primarily in the north bays and central region of the lake. If the heavy metals were sorted by the reduction of

  19. Sediment Metal Concentration Survey Along the Mine-Affected Molonglo River, NSW, Australia.

    PubMed

    Wadige, Chamani P M Marasinghe; Taylor, Anne M; Krikowa, Frank; Maher, William A

    2016-04-01

    Metal concentrations were measured in sediments of the mine-affected Molonglo River to determine current metal concentrations and distribution along the river. Compared with an uncontaminated site at 6.5 km upstream of the Captains Flat mine, sediments collected from the river at ≤12.5 km distance below the mine had a significantly higher percentage of finely divided silt and clay with higher concentrations of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn). The measured metal concentrations in the mine affected sites of the river were in the following order: Zn = 697-6818 > Pb = 23-1796 > Cu = 10-628 > Cd = 0.13-8.7 µg/g dry mass. The highest recorded metal concentrations were Cd at 48, Cu at 45, Pb at 240, and Zn at 81 times higher than the background concentrations of these metals in the river sediments. A clear sediment metal-contamination gradient from the mine site to 63 km downstream was established for Cd, Cu, Pb, and Zn in the river sediments. Compared with sediment metal concentrations before a major flood in 2010, only Zn concentrations increased. For all of the mine-affected sites studied, Cd and Zn concentrations exceeded the (ANZECC/ARMCANZ, Australian and New Zealand guidelines for fresh and marine water quality. Australian and New Zealand Environment and Conservation Council/Agriculture and Resource Management Council of Australia and New Zealand, 2000) interim sediment-quality guidelines low values for Cd (1.5 µg/g dry mass) and the high value for Zn (410 µg/g dry mass). Existing metal loads in the riverbed sediments may still be adversely affecting the river infauna. PMID:26795293

  20. Reducing sediment concentration and soil loss using organic and inorganic amendments at plot scale

    NASA Astrophysics Data System (ADS)

    Sadeghi, S. H. R.; Gholami, L.; Homaee, M.; Khaledi Darvishan, A.

    2015-01-01

    Although various organic and inorganic mulches are used for soil conservation purposes, the comparative effectiveness of them on soil characteristics has not been comprehensively considered from different aspects. The present study is therefore an attempt to determine the efficiency of straw mulch, manure and TA-200 polyacrylamide with respective rates of 500, 300 and 50 g m-2, respectively, in changing sediment concentration and soil loss. The experiments were conducted for sandy-loam soil (collected from the top 0-20 cm-layer) taken from a summer rangeland, the Alborz Mountains, Northern Iran under laboratory conditions with simulated rainfall intensities of 30, 50, 70 and 90 mm h-1 and the slope of 30%. The results showed that the straw mulch decreased soil concentration at rate of 45.60% compared to the control plots, and performed better than manure (8.98% reduction) and PAM (4.74% reduction). The results showed that the maximum reduction in sediment concentration and soil loss for all soil amendments occurred in the rainfall intensity of 90 mm h-1 with the rates of 58.69 and 63.24%, for straw mulch, 14.65 and 13.14%, for manure and 20.15 and 23.44% for TA-200, respectively.

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

    EPA Science Inventory

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

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

    PubMed

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

    2012-01-01

    Hurricanes are relatively frequent ecological disturbances that may cause potentially long-term impacts to the coastal environment. Hurricane Katrina hit the Mississippi Gulf Coast in August 2005, and caused a storm surge with the potential to change the trace element content of coastal surface sediments. In this study, surface estuarine and marine sediments were collected monthly following the storm from ten sites along the Mississippi Gulf Coast (Mobile Bay, Grand Bay Bayous Heron and Cumbest, Pascagoula, Ocean Springs, Biloxi Gulf, Back Biloxi Bay, Gulfport Gulf, Gulfport Courthouse Rd, and Gulfport Marina). Concentrations of V, Cr, Mn, Fe, Co, Ni, Zn, As, Cd, and Pb were measured by inductively coupled plasma-mass spectrometry to evaluate their temporal and spatial variations in the year following Hurricane Katrina. Sediments were characterized by pH, particle size distribution and total carbon and nitrogen content. Trace element contents of the sediments were determined in both <2 mm and <63 μm grain size fractions. Results revealed no significant temporal and spatial variability in trace element concentrations, in either size fraction. Potential ecological risk of the sediments was assessed by using NOAA SQuiRTs' guideline values; most concentrations remained below probable adverse effects guidelines to marine organisms suggesting that trace elements redistributed by Hurricane Katrina would not cause an adverse impact on resident organisms. Instead, the concentrations of trace elements were site-dependent, with specific contaminants relating to the use of the area prior to Hurricane Katrina. PMID:21494829

  3. Seasonal variation of monomethylmercury concentrations in surface sediments of the Tagus Estuary (Portugal).

    PubMed

    Canário, João; Branco, Vasco; Vale, Carlos

    2007-07-01

    Surface sediments (0-2cm) were collected at 40 sites along the Tagus Estuary in July and December 2004. The sediments were analysed for total mercury, monomethylmercury (MMHg) and interpretative parameters (e.g. redox potential, pH, C(org)). No significant differences in total Hg, pH, Al, Fe, Mn and C(org) were found between sediments collected in the two periods, but MMHg concentrations were higher in July. On average sediments were warmer and more reducing in summer. On the basis of these results, an increase of 7kg of MMHg (+37%) in surface sediments of the Tagus Estuary was estimated. Presumably higher temperatures in summer promote the increase of microbial activity and higher methylation rates. The alterations observed in this study point to the potential importance of seasonal changes in MMHg production at surface sediments with eventual changes in the MMHg uptake by benthic invertebrates and other organisms in the food web. PMID:17240023

  4. Zinc, copper, cadmium, and lead concentrations in water, sediment, and Anadara senilis in a tropical estuary.

    PubMed

    Bakary, Inza; Yao, Koffi Marcellin; Etchian, Olivier Assoi; Soro, Metongo Bernard; Trokourey, Albert; Bokra, Yobou

    2015-12-01

    Spatial and seasonal contaminations of zinc, copper, cadmium, and lead were assessed simultaneously in water, sediment, and in the bivalve Arca senilis from the Milliardaires Bay (Cote d'Ivoire) between February and October 2008. The metal load in sediments doubled from the dry season to the rainy season. On the contrary, metal concentrations in waters decreased significantly from the dry season to the rainy season. Zn and Pb concentrations in A. senilis showed similar seasonal variation with sediments. On the other hand, A. senilis regulated Cu concentrations by eliminating about twelve times the concentration accumulated during the dry season. Apparent Zn, Cu, Cd, and Pb concentration gradients were observed, but no significant differences between stations for sediment, water, and A. senilis. Concentrations in sediment increased from stations close to Abidjan Harbor towards farther stations, while concentrations in A. senilis showed a reverse gradient. The distribution gradient of A. senilis indicates pollution from local sources, but a transplant experiment is needed to better understand the observed spatial trend. Zn and Cu concentrations may pose little risk to human health and the environment, but they are the highest on the regional scale. On the contrary, Cd and Pb concentrations in A. senilis exceeded the maximum allowable limits set by the European Commission. Complementary studies including chemical speciation should be considered to provide a more accurate assessment of the risk of heavy metals to the environment. PMID:26581608

  5. Trends in sediment metal concentrations in the River Avoca, South-east Ireland.

    PubMed

    Gaynor, Anne; Gray, N F

    2004-12-01

    Variation in sediment metal concentrations in the River Avoca, which is severely polluted by acid mine drainage (AMD) discharged from the abandoned sulphur and copper mines in Avoca, is reported. A survey of surface and subsurface sediments was repeated after seven years during exceptionally low flow conditions in 2001. The present study found that the reference (up-stream) site used in the original 1994 study was itself impacted by AMD, showing sediment metal enrichment by AMD to be greater than originally thought. The new reference site contained elevated Pb (570 microg g(-1)) in the subsurface sediment due to abandoned Pb-Zn mines 25 km further upstream. Concentrations of Cu (43 microg g(-1)), Zn (349 microg g(-1)) and Fe (4.0%) were normal for uncontaminated rivers. All the downstream sites showed sediment metal enrichment arising from the AMD (Cu and Zn p < 0.001; Fe p < 0.01). Subsurface concentrations of metals immediately below the mixing zone were Cu 904 microg g-1 (sd 335), Zn 723 microg g-1 (sd 93), Fe 6.3% (sd 1.5) and Pb 463 microg g(-1) (sd 279). Monthly variation in metal concentrations at sites was not significantly different (p > 0.05). Although surface sediment metal concentrations were more variable, they followed similar trends to subsurface sediment. There were no significant differences in the subsurface sediment concentrations for either Cu or Zn over the period 1994 and 2001 immediately below the mines, although at the lowest site Zn had decreased by 35% over the period (p < 0.01). However there was a significant (p < 0.01) decrease over the period in the Fe concentration at all the impacted sites. This corresponds to a reduction in Fe concentration in the AMD and indicates that some remediation has occurred in the river since 1994. PMID:15719164

  6. Effective Discharge and Annual Sediment Yield on Brazos River

    NASA Astrophysics Data System (ADS)

    Rouhnia, M.; Salehi, M.; Keyvani, A.; Ma, F.; Strom, K. B.; Raphelt, N.

    2012-12-01

    Geometry of an alluvial river alters dynamically over the time due to the sediment mobilization on the banks and bottom of the river channel in various flow rates. Many researchers tried to define a single representative discharge for these morphological processes such as "bank-full discharge", "effective discharge" and "channel forming discharge". Effective discharge is the flow rate in which, the most sediment load is being carried by water, in a long term period. This project is aimed to develop effective discharge estimates for six gaging stations along the Brazos River from Waco, TX to Rosharon, TX. The project was performed with cooperation of the In-stream Flow Team of the Texas Water Development Board (TWDB). Project objectives are listed as: 1) developing "Flow Duration Curves" for six stations based on mean-daily discharge by downloading the required, additional data from U.S Geological Survey website, 2) developing "Rating Curves" for six gaging stations after sampling and field measurements in three different flow conditions, 3) developing a smooth shaped "Sediment Yield Histogram" with a well distinguished peak as effective discharge. The effective discharge was calculated using two methods of manually and automatic bin selection. The automatic method is based on kernel density approximation. Cross-sectional geometry measurements, particle size distributions and water field samples were processed in the laboratory to obtain the suspended sediment concentration associated with flow rate. Rating curves showed acceptable trends, as the greater flow rate we experienced, the more sediment were carried by water.

  7. Concentration Levels and Ecological Risks of Persistent Organic Pollutants in the Surface Sediments of Tianjin Coastal Area, China

    PubMed Central

    Lu, Xiaoxia; Chen, Chaoqi; Zhang, Shu; Hou, Zhen; Yang, Junjun

    2013-01-01

    Sediments were sampled from different surface water bodies in Tianjin coastal area, China, and persistent organic pollutants (POPs) including polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) were measured using GC/MS or GC/ECD. The purposes were to investigate the concentration levels of the POPs and to assess their ecological risks. The results showed that all the 16 priority PAHs were detected from the 10 sediments sampled with the total concentrations of the 16 PAHs ranging from 274.06 μg/kg to 2656.65 μg/kg, while the concentrations of the halogenated POPs were generally low except in the Dagu waste discharging river where the total concentrations of 24 OCPs, 35 PCBs, and 14 PBDEs were 3103.36 μg/kg, 87.31 μg/kg, and 13.88 μg/kg, respectively. In the studied sediments, PAHs exhibited risks to benthonic organisms; particularly the concentrations of naphthalene and/or acenaphthene exceeded their probable effect concentrations in several locations. In comparison, only in the Dagu waste discharging river, OCPs exhibited risks with the concentrations of heptachlor epoxide and lindane exceeding their probable effect concentrations. PCBs and PBDEs posed rare risks in the studied area. PMID:23401668

  8. Concentrations of Elements in Sediments and Selective Fractions of Sediments, and in Natural Waters in Contact with Sediments from Lake Roosevelt, Washington, September 2004

    USGS Publications Warehouse

    Paulson, Anthony J.; Wagner, Richard J.; Sanzolone, Richard F.; Cox, Steven E.

    2006-01-01

    Twenty-eight composite and replicate sediment samples from 8 Lake Roosevelt sites were collected and analyzed for 10 alkali and alkaline earth elements, 2 non-metals, 20 metals, and 4 lanthanide and actinide elements. All elements were detected in all sediment samples except for silver (95 percent of the elements detected for 1,008 analyses), which was detected only in 4 samples. Sequential selective extraction procedures were performed on single composite samples from the eight sites. The percentage of detections for the 31 elements analyzed ranged from 76 percent for the first extraction fraction using a weak extractant to 93 percent for the four-acid dissolution of the sediments remaining after the third sequential selective extraction. Water samples in various degrees of contact with the sediment were analyzed for 10 alkali and alkaline earth elements, 5 non-metals, 25 metals, and 16 lanthanide and actinide elements. The filtered water samples included 10 samples from the reservoir water column at 8 sites, 32 samples of porewater, 55 samples from reservoir water overlying sediments in 8 cores from the site incubated in a field laboratory, and 24 water samples that were filtered after being tumbled with sediments from 8 sites. Overall, the concentrations of only 37 percent of the 6,776 analyses of the 121 water samples were greater than the reporting limit. Selenium, bismuth, chromium, niobium, silver, and zirconium were not detected in any water samples. The percentage of concentrations for the water samples that were above the reporting limit ranged from 14 percent for the lanthanide and actinide elements to 77 percent for the alkali and alkaline earth elements. Concentrations were greater than reporting limits in only 23 percent of the analyses of reservoir water and 29 percent of the analyses of reservoir water overlying incubation cores. In contrast, 47 and 48 percent of the concentrations of porewater and water samples tumbled with sediments, respectively

  9. Concentration of arsenic in water, sediments and fish species from naturally contaminated rivers.

    PubMed

    Rosso, Juan José; Schenone, Nahuel F; Pérez Carrera, Alejo; Fernández Cirelli, Alicia

    2013-04-01

    Arsenic (As) may occur in surface freshwater ecosystems as a consequence of both natural contamination and anthropogenic activities. In this paper, As concentrations in muscle samples of 10 fish species, sediments and surface water from three naturally contaminated rivers in a central region of Argentina are reported. The study area is one of the largest regions in the world with high As concentrations in groundwater. However, information of As in freshwater ecosystems and associated biota is scarce. An extensive spatial variability of As concentrations in water and sediments of sampled ecosystems was observed. Geochemical indices indicated that sediments ranged from mostly unpolluted to strongly polluted. The concentration of As in sediments averaged 6.58 μg/g ranging from 0.23 to 59.53 μg/g. Arsenic in sediments barely followed (r = 0.361; p = 0.118) the level of contamination of water. All rivers showed high concentrations of As in surface waters, ranging from 55 to 195 μg/L. The average concentration of As in fish was 1.76 μg/g. The level of contamination with As differed significantly between species. Moreover, the level of bioaccumulation of As in fish species related to the concentration of As in water and sediments also differed between species. Whilst some fish species seemed to be able to regulate the uptake of this metalloid, the concentration of As in the large catfish Rhamdia quelen mostly followed the concentration of As in abiotic compartments. The erratic pattern of As concentrations in fish and sediments regardless of the invariable high levels in surface waters suggests the existence of complex biogeochemical processes behind the distribution patterns of As in these naturally contaminated ecosystems. PMID:23179469

  10. Regional background concentrations of heavy metals (Cr, Co, Ni, Cu, Zn, Pb) in coastal sediments of the South Sea of Korea.

    PubMed

    Song, Yunho; Choi, Man Sik; Lee, Ji Youn; Jang, Dong Jun

    2014-06-01

    The background concentration (BC) of metals in coastal sediments may be a useful tool for assessing the extent of sediment contamination by human activities. This study presents an approach to establish BCs that are applicable at the regional scale, particularly for coastal areas with relatively tortuous coastlines and complex coastal geology and/or geomorphology like the South Sea of Korea. The approach is based on the sorption hypothesis for metal enrichment of coastal sediments and was verified using 33 core and 187 surface sediments. The concentrations of major and heavy metals, grain size parameters, organic carbon, and sedimentation rates were determined. Cs was selected as the most suitable geochemical normalizer to correct the grain-size effect. Non-contaminated samples from core sediments were selected according to the sedimentation rate, 32 types of profile pattern based on metal concentrations and metal/Cs ratios, and their variability in past sediments. Metal concentrations in the selected non-contaminated samples were well correlated with Cs, with a given Cs amounts in surface sediments corresponding to the lowest metal concentrations. This result supported the use of a procedure based on the sorption hypothesis, which was then used to synthesize all core samples and establish the regional BC of heavy metals in the coastal sediments. Linear regression equations between metal and Cs concentrations provided the following BCs of metals in coastal sediments in the South Sea of Korea: 70 (Cr), 13 (Co), 30 (Ni), 13 (Cu), 87 (Zn), and 23 (Pb)mg/kg at 8mg/kg of Cs (mean concentration of 393 sediments). PMID:24636889

  11. Controls of suspended sediment concentration, nutrient content, and transport in a subtropical wetland

    USGS Publications Warehouse

    Noe, G.B.; Harvey, J.W.; Schaffranek, R.W.; Larsen, L.G.

    2010-01-01

    Redistribution of largely organic sediment from low elevation sloughs to higher elevation ridges is a leading hypothesis for the formation and maintenance of the native ridge and slough landscape pattern found in peat wetlands of the Florida Everglades. We tested this redistribution hypothesis by measuring the concentration and characteristics of suspended sediment and its associated nutrients in the flowpaths of adjacent ridge and slough plant communities. Over two wet seasons we found no sustained differences in suspended sediment mass concentrations, particle-associated P and N concentrations, or sizes of suspended particles between ridge and slough sites. Discharge of suspended sediment, particulate nutrients, and solutes were nearly double in the slough flowpath compared to the ridge flowpath due solely to deeper and faster water flow in sloughs. Spatial and temporal variations in suspended sediment were not related to water velocity, consistent with a hypothesis that the critical sheer stress causing entrainment is not commonly exceeded in the present-day managed Everglades. The uniformity in the concentrations and characteristics of suspended sediment at our research site suggests that sediment and particulate nutrient redistribution between ridges and sloughs does not occur, or rarely occurs, in the modern Everglades.

  12. Sediment concentrations and loads in the Loxahatchee River estuary, Florida, 1980-82

    USGS Publications Warehouse

    Sonntag, Wayne H.; McPherson, Benjamin F.

    1984-01-01

    This study was conducted to estimate the magnitude of sediment loads and the general spatial and temporal patterns of sediment transport in the Loxahatchee River estuary, Florida. Mean concentrations of suspended sediment generally were higher in the Jupiter Inlet area than in the remainder of the embayment area. Concentrations of suspended sediment varied with season and weather conditions. Concentrations in selected tributaries following Tropical Storm Dennis in August 1981 immediately increased as much as 16 times over concentrations before the storm. Suspended-sediment loads from the tributaries were also highly seasonal and storm related. During a 61-day period of above-average rainfall that included Tropical Storm Dennis, 5 major tributaries discharged 926 tons (short) of suspended sediment to the estuary, accounting for 74 percent of the input for the 1981 water year and 49 percent of the input for the 20-month study period. Suspended-sediment loads at Jupiter Inlet and at the mouth of the estuary embayment on both incoming and outgoing tides far exceeded tributary loads, but the direction of long-term, net tidal transport was not determined. (USGS)

  13. Bedload monitoring under conditions of ultra-high suspended sediment concentrations

    NASA Astrophysics Data System (ADS)

    Liébault, F.; Jantzi, H.; Klotz, S.; Laronne, J. B.; Recking, A.

    2016-09-01

    The bedload response of the Moulin Ravine, a small alluvial system draining a very active Mediterranean badlands landscape entrenched into Jurassic black marls of the Southern French Prealps, has been investigated using an automatic Reid bedload slot sampler. This site is known for its exceptional sediment transport conditions thanks to a long-term monitoring program that started in the late 1980s, revealing a mean annual bedload yield of 2810 t km-2 yr-1, and suspended sediment concentrations (SSCs) during flow events commonly reaching 100 g L-1. With the deployment of the slot sampler, it has been possible to record instantaneous bedload fluxes during 10 s time increments and to investigate bedload response under flow conditions with ultra-high SSCs. Bedload records cover 4 flashy summer flow events induced by heavy convective storms including a 20-yr return period event. Due to the very high SSC conditions these events challenge bedload monitoring. Even if slot sampling has been recognized as insensitive to fine sediments (silts and clays), it has never been tested in such exceptional muddy flow conditions. The bedload slot sampler performed well in such conditions. A flow-invariant proportion of fines (∼15-20%) was captured in the slot sampler during flows. This proportion is equivalent to its content in the active bedload layer during summer flows, suggesting that fines enter the slot embedded with coarse particles. Instantaneous bedload fluxes recorded in the Moulin are amongst the highest hitherto reported values worldwide, providing evidence of the exceptional sediment transport conditions of marly alpine badlands. The dimensionless entrainment threshold is one order of magnitude higher than commonly reported for gravel-bed rivers, likely reflecting the cohesion effect of fines intruded in the channel surface and subsurface.

  14. Combined use of remote sensing and continuous monitoring to analyse the variability of suspended-sediment concentrations in San Francisco Bay, California

    USGS Publications Warehouse

    Ruhl, C.A.; Schoellhamer, D.H.; Stumpf, R.P.; Lindsay, C.L.

    2001-01-01

    Analysis of suspended-sediment concentration data in San Francisco Bay is complicated by spatial and temporal variability. In situ optical backscatterance sensors provide continuous suspended-sediment concentration data, but inaccessibility, vandalism, and cost limit the number of potential monitoring stations. Satellite imagery reveals the spatial distribution of surficial-suspended sediment concentrations in the Bay; however, temporal resolution is poor. Analysis of the in situ sensor data in conjunction with the satellite reflectance data shows the effects of physical processes on both the spatial and temporal distribution of suspended sediment in San Francisco Bay. Plumes can be created by large freshwater flows. Zones of high suspended-sediment concentrations in shallow subembayments are associated with wind-wave resuspension and the spring-neap cycle. Filaments of clear and turbid water are caused by different transport processes in deep channels, as opposed to adjacent shallow water.

  15. Summary of suspended-sediment concentration data, San Francisco Bay, California, water year 2009

    USGS Publications Warehouse

    Buchanan, Paul A.; Morgan, Tara L.

    2012-01-01

    Suspended-sediment concentration data were collected by the U.S. Geological Survey in San Francisco Bay during water year 2009 (October 1, 2008–September 30, 2009). Optical sensors and water samples were used to monitor suspended-sediment concentration at two sites in Suisun Bay, one site in San Pablo Bay, two sites in Central San Francisco Bay, and one site in South San Francisco Bay. Sensors were positioned at two depths at most sites to help define the vertical variability of suspended sediments. Water samples were collected periodically and analyzed for concentrations of suspended sediment. The results of the analyses were used to calibrate the output of the optical sensors so that a record of suspended-sediment concentrations could be derived. This report presents the data-collection methods used and summarizes, in graphs, the suspended-sediment concentration data collected from October 2008 through September 2009. Calibration curves and plots of the processed data for each sensor also are presented.

  16. Summary of suspended-sediment concentration data, San Francisco Bay, California, water year 2010

    USGS Publications Warehouse

    Buchanan, Paul A.; Morgan, Tara L.

    2014-01-01

    Suspended-sediment concentration data were collected by the U.S. Geological Survey in San Francisco Bay during water year 2010 (October 1, 2009–September 30, 2010). Turbidity sensors and water samples were used to monitor suspended-sediment concentration at two sites in Suisun Bay, one site in San Pablo Bay, three sites in Central San Francisco Bay, and one site in South San Francisco Bay. Sensors were positioned at two depths at most sites to help define the vertical variability of suspended sediments. Water samples were collected periodically and analyzed for concentrations of suspended sediment. The results of the analyses were used to calibrate the output of the turbidity sensors so that a record of suspended-sediment concentrations could be computed. This report presents the data-collection methods used and summarizes, in graphs, the suspended-sediment concentration data collected from October 2009 through September 2010. Calibration curves and plots of the processed data for each sensor also are presented.

  17. Summary of Suspended-Sediment Concentration Data, San Francisco Bay, California, Water Year 2006

    USGS Publications Warehouse

    Buchanan, Paul A.; Lionberger, Megan A.

    2009-01-01

    Suspended-sediment concentration data were collected by the U.S. Geological Survey in San Francisco Bay during water-year 2006 (October 1, 2005-September 30, 2006). Optical sensors and water samples were used to monitor suspended-sediment concentration at two sites in Suisun Bay, one site in San Pablo Bay, two sites in Central San Francisco Bay, and one site in South San Francisco Bay. Sensors were positioned at two depths at most sites to help define the vertical variability of suspended sediments. Water samples were collected periodically and analyzed for concentrations of suspended sediment. The results of the analyses were used to calibrate the output of the optical sensors so that a record of suspended-sediment concentrations could be derived. This report presents the data-collection methods used and summarizes, in graphs, the suspended-sediment concentration data collected from October 2005 through September 2006. Calibration curves and plots of the processed data for each sensor also are presented.

  18. Influence of acid volatile sulfide and metal concentrations on metal bioavailability to marine invertebrates in contaminated sediments

    USGS Publications Warehouse

    Lee, B.-G.; Lee, J.-S.; Luoma, S.N.; Choi, H.J.; Koh, C.-H.

    2000-01-01

    allowed use of metal concentrations typical of nature and evaluation of processes important to chronic metal exposure. A vertical sediment column similar to that often found in nature was used to facilitate realistic biological behavior. Results showed that AVS or porewater (PW) metals controlled bioaccumulation in only 2 of 15 metal-animal combinations. Bioaccumulation of all three metals by the bivalves was related significantly to metal concentrations extracted from sediments (SEM) but not to [SEM - AVS] or PW metals. SEM predominantly influenced bioaccumulation of Ni and Zn in N. arenaceodentata, but Cd bioaccumulation followed PW Cd concentrations. SEM controlled tissue concentrations of all three metals in H. filiformis and S. missionensis, with minor influences from metal-sulfide chemistry. Significant bioaccumulation occurred when SEM was only a small fraction of AVS in several treatments. Three factors appeared to contribute to the differences between these bioaccumulation results and the results from toxicity tests reported previously: differences in experimental design, dietary uptake, and biological attributes of the species, including mode and depth of feeding.Microcosms were used to simulate environmentally realistic metal, acid volatile sulfide (AVS), and geochemical gradients in sediments to evaluate effects of metal bioavailability. The 18-d study involved five test species: two bivalves and three polychaetes. Two series of experiments were designed to evaluate the effects of metal concentration and AVS on bioaccumulation, respectively. The metals of interest were cadmium, nickel, and zinc. Results showed that the concentrations of pore-water Cd, Ni, and Zn were controlled by the concentration of AVS. Organisms bioaccumulated significant amounts of metals from the sediments when the simultaneously extracted metal was only a small fraction of the AVS. Bioavailability increased linearly with the sediment metal concentration irrespective of AVS or pore-w

  19. Morphological abnormalities in chironomidae in relation to sediment metals concentrations in Empire Lake, Cherokee County, Kansas

    SciTech Connect

    Ferringington, L.C. Jr.

    1994-12-31

    Morphological abnormalities of headcapsule structures of chironomid larvae were quantified in relation to concentrations of heavy metals in sediments of Empire Lake. This reservoir is situated in a catchment downstream of a US EPA Superfund Site in the Tri-State Mining District of southeast Kansas, and receives discharges from several streams that flow through the abandoned mining areas. Sediments have elevated concentrations of Zinc, Lead, and Cadmium in varying concentrations. Chironomini had the highest incidence of morphological abnormalities, followed by Procladius. Although deformities of the mentum, premandibles, and antennae were found in several taxa, no clear trends were seen for increasing concentrations of any of the metals individually or collectively. From this study it appears as if the incidence of morphological abnormalities is not a linear function of metals concentrations in sediments of this reservoir.

  20. Use of fluorometrically determined gut chlorophyll-a concentrations to assess toxicity of sediments to the amphipod Ampelisca verrilli

    SciTech Connect

    Maier, P.P.; Van Dolah, R.F.; Jones, J.D.

    1995-12-31

    Concentrations of contaminants which do not cause measurable mortality in traditional acute bioassays may cause sublethal effects including reduction in the ability of amphipods to collect and ingest food. Measurement of feeding efficiency can provide an early indication of toxic stress and it may represent a more sensitive measure of sediment toxicity. Experiments conducted in this study utilize a fluorometric method of chlorophyll determination to quantify feeding of Ampelisca verrilli. Replicate 500 ml beakers with 150 ml of test or control sediment and 300 ml of seawater are inoculated with ten amphipods. At the end of a 96 hour exposure period, concentrated algae is added to bring each beaker concentration up to 500,000 cells/ml. After feeding for 1 hour, amphipods are collected by sieving and weighed. The animals from each container are then ground in buffered acetone, centrifuged, and the chlorophyll-a concentration of the supernatant is measured. The final concentrations are expressed as {micro}g chl-a/mg wet-weight of amphipod. Results obtained from feeding assays using toxic sediments will be compared with data obtained from standard 10-day sediment toxicity tests to evaluate the relative sensitivity of this sublethal endpoint.

  1. Settlement success of Favia fragum planulae exposed to different sediment types and concentrations from southern Puerto Rico

    EPA Science Inventory

    Sedimentation has been reported to adversely affect coral ecosystems, but the precise effects of sediment on coral larval settlement and metamorphosis are not well understood. Planulae from laboratory-cultured Favia fragum colonies were collected and exposed to sediment collected...

  2. Reducing sediment concentration and soil loss using organic and inorganic amendments at plot scale

    NASA Astrophysics Data System (ADS)

    Sadeghi, S. H. R.; Gholami, L.; Homaee, M.; Khaledi Darvishan, A.

    2015-04-01

    Various organic and inorganic mulches are used for soil conservation purposes, the effectiveness of which on soil characteristics has not been comprehensively considered from different aspects. The present study surveys the efficiency of straw mulch, manure and TA-200 polyacrylamide with respective rates of 500, 300 and 50 g m-2 in changing sediment concentration and soil loss. The experiments were conducted for sandy-loam soil taken from a summer rangeland, the Alborz Mountains, northern Iran. The experiments were performed under laboratory conditions with simulated rainfall intensities of 30, 50, 70 and 90 mm h-1 and a slope of 30%. The results showed that the straw mulch decreased soil erosion at rate of 45.60% compared to the control plots and performed better than manure (8.98% reduction) and PAM (4.74% reduction). The results showed that the maximum reduction in sediment concentration and soil loss for all soil amendments occurred at the rainfall intensity of 90 mm h-1 with the rates of 58.69 and 63.24% for straw mulch, 14.65 and 13.14% for manure and 20.15 and 23.44% for TA-200.

  3. Concentration of selected trace elements and PCBs in sediments from the Adriatic Sea

    SciTech Connect

    Fowler, S W; Hamilton, T F; Coquery, M; Villeneuve, J-P; Horvat, M

    2000-07-26

    A broad baseline study of the levels and distributions of trace metals and PCB compounds in sediments has been undertaken. PCB concentrations in surface sediments reflect the source of these contaminates in the region. The highest PCB concentrations as Aroclor 1260 (approximately 10 ng g{sup -1}) were found in sediments near the outflow of the Po river. The lowest concentrations (1.5 ng g{sup -1} dry) were associated with the sediments from the Jabuka Pit in the Middle Adriatic. These values are quite similar to total PCBs (<1.0-17) measured in surface sediments sampled off the coast of Croatia in 1977-78. Thus, based on the limited amount of new data available, it appears that there has been little, if any, decrease in PCB loading in Adriatic sediments over the past 15 years. Downcore profiles of PCBs in sediment cores are also discussed from a pollution history standpoint. Likewise, total mercury in surface sediments was also highest at stations off the Po (403-499 ng g{sup -1} dry) and lowest (67-224 ng g{sup -1}) in the Jabuka Pit. In one core located just south of the Po outflow, total Hg concentrations at all depths were relatively high decreasing gradually from approximately 400 ng g{sup -1} in the top 4 cm to roughly 200 ng g{sup -1} at a depth of 32 cm. Using a {sup 210}Pb-derived sedimentation rate of 0.26 em Y{sup -1} for this station, it appears that anthropogenic inputs of mercury may have been responsible for the gradual increase in total mercury noted over the last 125 years.

  4. Investigating changes in suspended sediment concentrations in the Peace-Athabasca Delta, Canada using MODIS satellite imagery

    NASA Astrophysics Data System (ADS)

    Long, C.; Pavelsky, T. M.

    2011-12-01

    Changes in the magnitude, distribution, and timing of sedimentary recharge to a freshwater delta have the potential to significantly affect the delta's hydrology, geomorphology, and ecology. The Peace-Athabasca Delta (PAD) in northeastern Alberta, Canada is one system potentially facing significant changes due to substantial decreases in discharge from the Athabasca River into the delta over at least the past four decades. We use bands 1 and 2 of daily 250-m Moderate-Resolution Imaging Spectroradiometer (MODIS) imagery, published river discharge data, and field measurements of suspended sediment concentrations to determine the effects of the decrease in Athabasca River flow on the delivery of sediment throughout the PAD. Daily MODIS images for every summer (May-September) from 2000 to 2011 are used to track the timing, magnitude, and spatial characteristics of the delivery and distribution of high sediment water from the Athabasca River into the delta. Comparison of this time-series of satellite images allows us to examine changes in sedimentary recharge throughout the last decade. Preliminary analysis for 2002 (the lowest water year of the decade) and 2005 (the highest water year) show that in 2005 the amount of sediment delivered to the delta was significantly higher than it was in 2002. This suggests that changes in river discharge do affect the delivery of sediment into the delta. Analysis of MODIS images also reveals that not all areas of the PAD are equally recharged with sediment with any given discharge from the Athabasca River. By comparing the spatial distribution of sediment with same-day discharge on the Athabasca River, we can determine flow thresholds required to deliver sediment to individual lakes. A map of these thresholds allows us to then identify which portions of the PAD are no longer being recharged with sediment under current flow conditions and which additional areas could be particularly vulnerable to further decreases in Athabasca River

  5. Natural and artificial radionuclide activity concentrations in surface sediments of Izmit Bay, Turkey.

    PubMed

    Ergül, Halim Aytekin; Belivermiş, Murat; Kılıç, Önder; Topcuoğlu, Sayhan; Çotuk, Yavuz

    2013-12-01

    Surface sediments from the north-eastern coast of the Marmara Sea, Turkey's most industrialized coastal region, were enriched with radioisotopes from the Chernobyl explosion in 1986. Caesium-137 in these sediments is also thought to originate from one former paper mill located nearby that used wood contaminated by Chernobyl explosion-originated (137)Cs for paper production. The average activity concentration of the (137)Cs was 21 Bq kg(-1), while naturally occurring radioisotopes, i.e. (40)K, (226)Ra, and (228)Ra, were 568, 18 and 24 Bq kg(-1), respectively, in surface sediments. The natural radionuclide activities reached their highest levels near petrochemical, phosphate and fertilizer processing facilities. Average (137)Cs activities were generally up to ten times higher than in Middle Eastern marine sediments and lower than those in Northern European sediments. PMID:23981563

  6. Cadmium distribution in sediment and the lugworm Arenicola marina in a low concentration exposure experiment

    SciTech Connect

    Everaarts, J.M.; SaralaDevi, K.

    1996-12-31

    In the central and southern North Sea, and in the Dutch coastal zone, total cadmium (Cd) concentrations in water are 0.02 {+-} 0.01 {mu}g/L and 0.06 {+-} 0.02 {mu}g/L, respectively Cadmium in the estuarine waters of the Dutch Wadden Sea varied from 0.3 {+-} 0.01 {mu}g/L in the western part to 0.08 {+-} 0.03 {mu}g/L in the eastern part. In whole sediment, the Cd background concentration for the Wadden Sea is 0.5 {+-} 0.01 {mu}g/g dry weight (dw), whereas the reference concentration is 0.08 {+-} 0.02 {mu}g/g dw. The concentrations of total-Cd in surface bulk sediments (0-2 cm) of the central North Sea (Oyster Grounds), and of intertidal mud-flats in the western Wadden Sea varied from 0.05 to 0.15 {mu}g/g dw and from 0.13 to 0.46 {mu}g dw, respectively (calculated from Kahn et al. 1992). These concentration ranges match the reference Cd concentration for Wadden Sea whole sediment (0.5 {+-} 0.01) {mu}g/g dw. Cadmium concentrations in surface sediments of the Dutch coastal zone and estuaries are only slightly elevated compared to the 0.2 {mu}g/g dw, considered as the background concentrations in pristine areas, but well below the level of 10 {mu}g/g dw at heavily contaminated sites. This laboratory study reports on the distribution of cadmium in the sediment column, and the uptake in the blood/coelomic fluid, intestine and body-wall of lugworms at low cadmium concentration exposure. The aim was to determine possible interaction between the vertical distribution of sediment-bound cadmium and the bioturbating activity of lugworms. 14 refs., 3 figs., 2 tabs.

  7. Effectiveness of bioremediation in reducing toxicity in oiled intertidal sediments

    SciTech Connect

    Lee, K.; Tremblay, G.H.; Siron, R.

    1995-12-31

    A 123-day field study was conducted with in situ enclosures to compare the effectiveness of bioremediation strategies based in inorganic and organic fertilizer additions to accelerate the biodegradation rates and reduce the toxicity of Venture{trademark} condensate stranded within sand-beach sediments. Comparison of the two fertilizer formulations with identical nitrogen and phosphorus concentrations showed that the organic fertilizer stimulated bacterial productivity within the oiled sediments to the greatest extent. However, detailed chemical analysis indicated that inorganic fertilizer additions were the most effective in enhancing condensate biodegradation rates. The Microtox{reg_sign} Solid-Phase Test (SPT) bioassay was determined to be sensitive to Venture Condensate in laboratory tests. Subsequent application of this procedure to oiled sediment in the field showed a reduction in sediment toxicity over time. However, the Microtox{reg_sign} bioassay procedure did not identify significant reductions in sediment toxicity following bioremediation treatment. An observed increase in toxicity following periodic additions of the organic fertilizer was attributed to rapid biodegradation rates of the fertilizer, which resulted in the production of toxic metabolic products.

  8. Background concentrations of radionuclides in soils and river sediments in northern New Mexico, 1974-1986

    SciTech Connect

    Purtymun, W.D.; Peters, R.J.; Buhl, T.E.; Maes, M.N.; Brown, F.H.

    1987-11-01

    This report documents the range and the upper limit for background concentrations of radionuclides and radioactivity in soils and river sediments that occur as natural rock-forming minerals and worldwide fallout from atmospheric nuclear weapons tests. Documentation is based on the collection of soil and sediment in northern New Mexico and analyzed for /sup 137/Cs, /sup 238/Pu, /sup 239,240/Pu, /sup 90/Sr, total uranium, gross gamma, and tritium. The data used to establish the statistical range and upper limit of background concentration cover a 9- or 13-year period ending in 1986. The knowledge of background levels is necessary to interpret soil and sediment data collected for the annual environmental surveillance report and other reports relating to radionuclides or radioactivity in soils and sediments. 11 refs., 1 fig., 5 tabs.

  9. PAHs concentration and toxicity in organic solvent extracts of atmospheric particulate matter and sea sediments.

    PubMed

    Ozaki, Noriatsu; Takeuchi, Shin-ya; Kojima, Keisuke; Kindaichi, Tomonori; Komatsu, Toshiko; Fukushima, Takehiko

    2012-01-01

    The concentration of polycyclic aromatic hydrocarbons (PAHs) and the toxicity to marine bacteria (Vibrio fischeri) were measured for the organic solvent extracts of sea sediments collected from an urban watershed area (Hiroshima Bay) of Japan and compared with the concentrations and toxicity of atmospheric particulate matter (PM). In atmospheric PM, the PAHs concentration was highest in fine particulate matter (FPM) collected during cold seasons. The concentrations of sea sediments were 0.01-0.001 times those of atmospheric PM. 1/EC50 was 1-10 L g(-1) PM for atmospheric PM and 0.1-1 L g(-1) dry solids for sea sediments. These results imply that toxic substances from atmospheric PM are diluted several tens or hundreds of times in sea sediments. The ratio of the 1/EC50 to PAHs concentration ((1/EC50)/16PAHs) was stable for all sea sediments (0.1-1 L μg(-1) 16PAHs) and was the same order of magnitude as that of FPM and coarse particulate matter (CPM). The ratio of sediments collected from the west was more similar to that of CPM while that from the east was more similar to FPM, possibly because of hydraulic differences among water bodies. The PAHs concentration pattern analyses (principal component analysis and isomer ratio analysis) were conducted and the results showed that the PAHs pattern in sea sediments was quite different to that of FPM and CPM. Comparison with previously conducted PAHs analyses suggested that biomass burning residues comprised a major portion of these other sources. PMID:22797225

  10. Spatial variability of suspended sediment concentration within a tidal marsh in San Francisco Estuary

    NASA Astrophysics Data System (ADS)

    Swanson, K.; Drexler, J. Z.; Schoellhamer, D. H.; Buffington, K.; Takekawa, J.

    2012-12-01

    The sustainability of existing marshes and feasibility of future marsh restoration projects in San Francisco Estuary and elsewhere are threatened by a potential imbalance between accelerating sea-level rise and tidal marsh accretion rates. Marsh accretion is, in large part, dependent upon the availability of suspended sediment supplied from adjacent waterways. As water and sediment move across a marsh plain, suspended sediment settles and is trapped by vegetation near the source, resulting in less suspended-sediment concentration (SSC) and deposition in the interior of the marsh. Measurements of deposition and limited observations of SSC within marshes have confirmed a decrease in sediment supply and accumulation from the marsh edge to the marsh interiors, but the spatial variability of SSC has not been quantified in a manner that allows for comparison to a theoretical sediment transport model. For this study, transects of SSC were collected within a marsh at China Camp State Park in the San Francisco Estuary which demonstrate that a dominant pattern of settling can be quantified and generally matches the exponentially decreasing pattern of SSC predicted by a simple advection-settling model. The observed pattern suggests that sediment settling and marsh flow characteristics are consistent both spatially (between transects) and temporally (between monthly sampling events). However, deviations from the predicted pattern occurred systematically at some locations and are likely related to resuspension of sediment from the marsh surface or small, unmapped creek channels that supply sediment to the marsh. Despite these deviations, our data show this simple 1-D model of advection and settling can be used to generalize within-marsh sediment transport as a function of distance from the nearest sediment source.

  11. Continuous automated sensing of streamflow density as a surrogate for suspended-sediment concentration sampling

    USGS Publications Warehouse

    Larsen, Matthew C.; Figueroa Alamo, Carlos; Gray, John R.; Fletcher, William

    2001-01-01

    A newly refined technique for continuously and automatically sensing the density of a water-sediment mixture is being tested at a U.S. Geological Survey streamflow-gaging station in Puerto Rico. Originally developed to measure crude oil density, the double bubbler instrument measures fluid density by means of pressure transducers at two elevations in a vertical water column. By subtracting the density of water from the value measured for the density of the water-sediment mixture, the concentration of suspended sediment can be estimated. Preliminary tests of the double bubbler instrument show promise but are not yet conclusive.

  12. Onsager’s reciprocal relations for electroacoustic and sedimentation: Application to (concentrated) colloidal suspensions

    SciTech Connect

    Gourdin-Bertin, S.; Chassagne, C.

    2015-05-21

    In this article, the relations for electroacoustic phenomena, such as sedimentation potential, sedimentation intensity, colloid vibration potential, colloid vibration intensity/current, or electric sonic amplitude, are given, on the basis of irreversible thermodynamics. This formalism allows in particular to discuss the different expressions for concentrated suspensions found by various authors, which are of great practical interest. It was found that some existing expressions have to be corrected. Relations between the electrophoretic mobilities assessed by the different experiments are derived.

  13. Onsager's reciprocal relations for electroacoustic and sedimentation: Application to (concentrated) colloidal suspensions

    NASA Astrophysics Data System (ADS)

    Gourdin-Bertin, S.; Chassagne, C.

    2015-05-01

    In this article, the relations for electroacoustic phenomena, such as sedimentation potential, sedimentation intensity, colloid vibration potential, colloid vibration intensity/current, or electric sonic amplitude, are given, on the basis of irreversible thermodynamics. This formalism allows in particular to discuss the different expressions for concentrated suspensions found by various authors, which are of great practical interest. It was found that some existing expressions have to be corrected. Relations between the electrophoretic mobilities assessed by the different experiments are derived.

  14. Chronic effects of organochlorine exposure in sediment to the marine polychaete Neanthes arenaceodentata

    SciTech Connect

    Murdoch, M.H.; Chapman, P.M.; Johns, D.M.; Paine, M.D.

    1997-07-01

    Organisms exposed to organochlorinated compounds in sediments are likely to suffer chronic rather than acute effects. Thus, acute toxicity tests are unlikely to truly assess their potential impact. A 120-d toxicity test was designed to assess the impact of polychlorinated biphenyl on the marine polychaete Neanthes arenacedodentata. A two-tiered approach was used: Tier 1 involved reference sediment spiked with a range of concentrations of the organochlorine bracketing the concentrations found in natural sediments, and tier 2 involved field sediments collected from a coastal area contaminated with high concentrations of the same organochlorine. Testing measured a number of endpoints, including survival, growth, and reproduction. Survival and growth were unaffected in either tier by any of the test sediments. Reproductive endpoints, however, were depressed in both tiers relative to the reference sediment.

  15. The influence of grain size, grain color, and suspended-sediment concentration on light attenuation: Why fine-grained terrestrial sediment is bad for coral reef ecosystems

    NASA Astrophysics Data System (ADS)

    Storlazzi, Curt D.; Norris, Ben K.; Rosenberger, Kurt J.

    2015-09-01

    Sediment has been shown to be a major stressor to coral reefs globally. Although many researchers have tested the impact of sedimentation on coral reef ecosystems in both the laboratory and the field and some have measured the impact of suspended sediment on the photosynthetic response of corals, there has yet to be a detailed investigation on how properties of the sediment itself can affect light availability for photosynthesis. We show that finer-grained and darker-colored sediment at higher suspended-sediment concentrations attenuates photosynthetically active radiation (PAR) significantly more than coarser, lighter-colored sediment at lower concentrations and provide PAR attenuation coefficients for various grain sizes, colors, and suspended-sediment concentrations that are needed for biophysical modeling. Because finer-grained sediment particles settle more slowly and are more susceptible to resuspension, they remain in the water column longer, thus causing greater net impact by reducing light essential for photosynthesis over a greater duration. This indicates that coral reef monitoring studies investigating sediment impacts should concentrate on measuring fine-grained lateritic and volcanic soils, as opposed to coarser-grained siliceous and carbonate sediment. Similarly, coastal restoration efforts and engineering solutions addressing long-term coral reef ecosystem health should focus on preferentially retaining those fine-grained soils rather than coarse silt and sand particles.

  16. The influence of grain size, grain color, and suspended-sediment concentration on light attenuation: why fine-grained terrestrial sediment is bad for coral reef ecosystems

    USGS Publications Warehouse

    Storlazzi, Curt; Norris, Benjamin; Rosenberger, Kurt

    2015-01-01

    Sediment has been shown to be a major stressor to coral reefs globally. Although many researchers have tested the impact of sedimentation on coral reef ecosystems in both the laboratory and the field and some have measured the impact of suspended sediment on the photosynthetic response of corals, there has yet to be a detailed investigation on how properties of the sediment itself can affect light availability for photosynthesis. We show that finer-grained and darker-colored sediment at higher suspended-sediment concentrations attenuates photosynthetically active radiation (PAR) significantly more than coarser, lighter-colored sediment at lower concentrations and provide PAR attenuation coefficients for various grain sizes, colors, and suspended-sediment concentrations that are needed for biophysical modeling. Because finer-grained sediment particles settle more slowly and are more susceptible to resuspension, they remain in the water column longer, thus causing greater net impact by reducing light essential for photosynthesis over a greater duration. This indicates that coral reef monitoring studies investigating sediment impacts should concentrate on measuring fine-grained lateritic and volcanic soils, as opposed to coarser-grained siliceous and carbonate sediment. Similarly, coastal restoration efforts and engineering solutions addressing long-term coral reef ecosystem health should focus on preferentially retaining those fine-grained soils rather than coarse silt and sand particles.

  17. Effects of waste discharges on Mississippi River sediments

    SciTech Connect

    Lin, S.D.; Evans, R. )

    1987-11-01

    Bottom sediments in the Mississippi River at East St. Louis, Illinois, were studied to determine the effect of discharging water treatment wastes into the river. Average quantities of water treated were 30 mgd by the conventional process and 13.5 mgd by hydrotreators. In this plant the principle sources of waste were flocculators, settling basins, clarifiers, and filters. The nature of the wastes was characterized as the suspended solids content of the raw water and the aluminum or iron hydroxide generated by coagulation. Average daily solids released from all filters was 4,180 lb. Waste discharges increased the iron, aluminum, moisture, and organics content of the sediments and changed the particle size distribution of the sediments. Changes were observed at three of the 35 sampling stations. The area of influence was about 100 ft offshore and 3,300 ft downstream of the outfall. Within this affected zone iron and aluminum concentrations increased 3.4- and 8-fold above the background concentrations of 2,490 and 760 mg/liter, respectively. During a waste discharge at normal river flow, sediments consisted of 92% sand, 8% gravel, and no silt and clay. However, at low flow silt and clay were found at two protected stations. This derived from the reintroduction of river silt and clay captured during treatment. No unnatural sludge deposit was found within the area of waste discharge influence. No measurable effects from the discharge were found one week after cleaning of the basins.

  18. PAH related effects on fish in sedimentation ponds for road runoff and potential transfer of PAHs from sediment to biota.

    PubMed

    Grung, Merete; Petersen, Karina; Fjeld, Eirik; Allan, Ian; Christensen, Jan H; Malmqvist, Linus M V; Meland, Sondre; Ranneklev, Sissel

    2016-10-01

    Road runoff is an important source of pollution to the aquatic environment, and sedimentation ponds have been installed to mitigate effects on the aquatic environment. The purpose of this study was to investigate if a) fish from sedimentation ponds were affected by road pollution and; b) the transfer of PAHs from road runoff material to aquatic organisms was substantial. Minnow from a sedimentation pond (Skullerud) near Oslo (Norway) had higher levels of CYP1A enzyme and DNA stand breaks than minnow from the nearby river, but high concentrations of PAH-metabolites in bile revealed that both populations were highly exposed. Principal component analysis revealed that CYP1A and age of fish were correlated, while levels of PAH-metabolites were not correlated to CYP1A or DNA damage. Minnow from a lake un-affected by traffic had much lower levels of PAH-metabolites than the exposed fish, and also an improved condition. The latter results indicate that fish health was affected by road runoff. A closer investigation of PAH levels of the ecosystems of two sedimentation ponds (Skullerud and Vassum) and nearby environments were conducted. The concentration of the 16 EPA PAHs in sediments of the sedimentation ponds were high (1900-4200ngg(-1)), and even higher levels were observed in plants. Principal component analysis of selected ion chromatograms of PAHs showed a clear separation of plants vs. sediments. The plants preferentially accumulated the high molecular PAHs, both from sedimentation ponds with a petrogenic PAH isomer ratio in sediments; and from a lake with pyrogenic PAH isomer ratio in sediments. PMID:27267726

  19. ANN modelling of sediment concentration in the dynamic glacial environment of Gangotri in Himalaya.

    PubMed

    Singh, Nandita; Chakrapani, G J

    2015-08-01

    The present study explores for the first time the possibility of modelling sediment concentration with artificial neural networks (ANNs) at Gangotri, the source of Bhagirathi River in the Himalaya. Discharge, rainfall and temperature have been considered as the main controlling factors of variations in sediment concentration in the dynamic glacial environment of Gangotri. Fourteen feed forward neural networks with error back propagation algorithm have been created, trained and tested for prediction of sediment concentration. Seven models (T1-T7) have been trained and tested in the non-updating mode whereas remaining seven models (T1a-T7a) have been trained in the updating mode. The non-updating mode refers to the scenario where antecedent time (previous time step) values are not used as input to the model. In case of the updating mode, antecedent time values are used as network inputs. The inputs applied in the models are either the variables mentioned above as individual factors (single input networks) or a combination of them (multi-input networks). The suitability of employing antecedent time-step values as network inputs has hence been checked by comparative analysis of model performance in the two modes. The simple feed forward network has been improvised with a series parallel non-linear autoregressive with exogenous input (NARX) architecture wherein true values of sediment concentration have been fed as input during training. In the glacial scenario of Gangotri, maximum sediment movement takes place during the melt period (May-October). Hence, daily data of discharge, rainfall, temperature and sediment concentration for five consecutive melt periods (May-October, 2000-2004) have been used for modelling. High Coefficient of determination values [0.77-0.88] have been obtained between observed and ANN-predicted values of sediment concentration. The study has brought out relationships between variables that are not reflected in normal statistical analysis. A

  20. Distribution of the concentration of heavy metals associated with the sediment particles accumulated on road surfaces.

    PubMed

    Zafra, C A; Temprano, J; Tejero, I

    2011-07-01

    The heavy metal pollution caused by road run-off water constitutes a problem in urban areas. The metallic load associated with road sediment must be determined in order to study its impact in drainage systems and receiving waters, and to perfect the design of prevention systems. This paper presents data regarding the sediment collected on road surfaces in the city of Torrelavega (northern Spain) during a period of 65 days (132 samples). Two sample types were collected: vacuum-dried samples and those swept up following vacuuming. The sediment loading (g m(-2)), particle size distribution (63-2800 microm) and heavy metal concentrations were determined. The data showed that the concentration of heavy metals tends to increase with the reduction in the particle diameter (exponential tendency). The concentrations ofPb, Zn, Cu, Cr, Ni, Cd, Fe, Mn and Co in the size fraction <63 microm were 350, 630, 124, 57, 56, 38, 3231, 374 and 51 mg kg(-1), respectively (average traffic density: 3800 vehicles day(-1)). By increasing the residence time of the sediment, the concentration increases, whereas the ratio of the concentration between the different size fractions decreases. The concentration across the road diminishes when the distance between the roadway and the sampling siteincreases; when the distance increases, the ratio between size fractions for heavy metal concentrations increases. Finally, the main sources of heavy metals are the particles detached by braking (brake pads) and tyre wear (rubber), and are associated with particle sizes <125 microm. PMID:21882553

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

    NASA Astrophysics Data System (ADS)

    Lee, G. H.; Park, H. B.

    2014-12-01

    Acoustic Doppler Current Profiler (ADCP), designed for measuring velocity profile, is now widely used for the estimation of suspended sediment concentration from acoustic backscatter intensity, but its application to estuarine environments has not been vigorously tested. In this study, we examined the inversion capability of two ADCPs with 600 and 1200 kHz at three Korean estuaries: macrotidal Han river estuary (HRE), microtidal Nakdong river estuary (NRE), and anthropogenically altered macrotidal Yeongsan river estuary (YRE). In particular, we examined the relative importance of the sound attenuations due to water (aw) and sediment (as) in response to sediment characteristics (size and concentration) as well as changing salinity and temperature. The inverted concentration was compared with reference concentrations obtained either water samples or Optical Backscatter Sensors. In NRE and YRE, where suspended sediment concentrations were smaller than 0.2 kg/m3, the acoustic inversion performed poorly only with as (R2 = 0.05 and 0.39 for NRE and YRE, respectively), but well with aw (R2 = 0.70 and 0.64 for NRE and YRE, respectively). Thus, it is important to accurately constrain aw in low-concentration estuarine environments. However, we did not find that the varying aw performed considerably better than the constant aw. On the other hand, the acoustic inversion was poorest at HRE regardless of aw and as (R2 = 0.58 and mean relative error =45%). The large discrepancy appears to result from the poorly constrained, spatially and temporally varying sediment characteristics (grain size, density and concentration) due to non-local sediment transport at macrotidal HRE.

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

    NASA Astrophysics Data System (ADS)

    Lee, Guan-hong; Park, Hyo-Bong

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Park, Hyo-Bong; Lee, Guan-hong

    2016-03-01

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

  4. Suspended sediment behavior in a coastal dry-summer subtropical catchment: Effects of hydrologic preconditions

    NASA Astrophysics Data System (ADS)

    Gray, A. B.; Warrick, J. A.; Pasternack, G. B.; Watson, E. B.; Goñi, M. A.

    2014-06-01

    Variation in fluvial suspended sediment-discharge behavior is generally thought to be the product of changes in processes governing the delivery of sediment and water to the channel. The objective of this study was to infer sediment supply dynamics from the response of suspended sediment behavior to antecedent hydrologic factors. The Salinas River (California) is seasonally active, moderately sized, and potentially susceptible to lasting impacts of hydrologic event history because of aridity, high discharge variability, and in-channel terminating flows. Forty-five years of suspended sediment data from the lower Salinas and 80 years of hydrologic data were used to construct hydrologic descriptors of basin preconditioning and to test the effects of these preconditions on suspended sediment behavior. Hydrologic precondition factors - including change in mean daily discharge and increasing elapsed time since the last moderate discharge event (~ 10-20 times mean discharge (Qmean)) - were found to have significant positive effects on discharge-corrected, fine suspended-sediment concentrations. Conversely, increased elapsed time since the last low discharge event (~ 0.1-0.4 times Qmean), and the sum of low flow conditions over interannual time scales were found to cause significant negative trends in fine suspended sediment concentration residuals. Suspended sand concentrations are suppressed by increased elapsed time after threshold discharges of ~ 0.1-2 and 5-100 times Qmean, and increased low to no flow days over time scales from 1 to 2000 days. Current and previous year water yield and precipitation magnitudes correlate positively with sand concentration. Addition of fine sediment from lower Salinas hillslope or channel sources on the rising limb of the hydrograph is the major mechanism behind an overall positive hysteretic pattern, which was forensically supported by the annual occurrence of in-channel suspended sediment deposition by early season, channel

  5. Biogeochemical Control on the Flux of Trace Elements from Estuarine Sediments: Water Column Oxygen Concentrations and Benthic Infauna

    NASA Astrophysics Data System (ADS)

    Riedel, Gerhardt F.; Sanders, James G.; Osman, Richard W.

    1997-01-01

    Trace element (arsenic, copper and manganese) fluxes between sediment and water were examined for approximately 2 months in replicated sediment/water microcosms. Treatments consisted of three oxygen levels in the water column (saturated, 10% saturation and anaerobic) and three different organism treatments (control, Macoma balthicaand Nereis succinea). Both arsenic and manganese were released from the sediment in the anoxic treatment, while copper was lost from the water. With the water column either saturated or at 10% oxygen saturation, both arsenic and manganese fluxes were negligible. In contrast, copper fluxes out of the sediment increased with increasing oxygen concentrations. The effect of organisms on the trace element fluxes were greatest immediately after their introduction to the microcosms, and declined substantially thereafter. Nereiscaused a substantial initial increase in manganese fluxes, but caused a negative flux (out of the water column) for arsenic. Macomahad a much smaller effect on flux than Nereis. Neither organism had a substantial effect on copper fluxes. Porewater profiles gave good predictions of arsenic and manganese fluxes in the anoxic treatment, but not in the 10% or saturated-oxygen treatments. Porewater profiles underestimated copper fluxes in the oxygenated treatments somewhat, and predicted copper flux in the opposite direction in the anoxic treatment. These results suggest that the annual cycle of anoxia in systems like Chesapeake Bay, and the resulting annual cycle of organism death and recruitment, can significantly alter the cycling of trace elements between the sediment and water column.

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

    SciTech Connect

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

    2000-02-01

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

  7. CONTAMINATED SEDIMENTS - ECOLOGICAL EFFECTS RESEARCH

    EPA Science Inventory

    NHEERL's research in this area focuses on ecological effects of bioaccumulative chemicals, such as PCBs. The research is designed with recognition that sites of different size and complexity require bioaccumulation models with correspondingly complex and/or extensive data requir...

  8. Acoustic observations of near-bed sediment concentration and flux statistics above migrating sand dunes

    NASA Astrophysics Data System (ADS)

    Wilson, G. W.; Hay, A. E.

    2016-06-01

    A coherent Doppler profiler was used to measure coincident time series of velocity (u,w), sediment mass concentration (c), and sediment grain size (d), above mobile sand dunes in unidirectional flow (˜1 m/s, ˜1 m water depth). The measurements are used to extract statistical distributions of sediment concentration and flux just above the bed. Observed mass fluxes (uc,wc) were well fit by quasi-exponential distributions, at all positions along the dune profile, similar to previous observations of single-particle momenta for bed load over flat beds. Observed concentrations of moving particles were well fit by negative-binomial distributions, also similar to previous observations over flat beds. These probability distributions relate to two recent stochastic theories, previously derived and verified for uniform flow over flat beds. It is hypothesized that these theories may also be used as a local approximation in natural-scale flows with bed forms.

  9. Estimating flow concentration and sediment redistribution in shrub-dominated rangeland communities

    NASA Astrophysics Data System (ADS)

    Nouwakpo, S. K.; Weltz, M.; McGwire, K. C.; Rossi, C.

    2014-12-01

    In arid and semi-arid rangelands where vegetation is typically sparse, a synergistic relationship is assumed to exist between spatial distribution of plants and hydrologic and erosion processes. It is believed that areas underneath plant canopy have been conditioned to act as sediment, nutrients and water sinks whereas interspaces evolve into flow concentration pathways acting as source areas. This vegetation - hydrology feedback mechanism is part of a broader Vegetation Driven Spatial Heterogeneity (VDSH) concept that has been traditionally studied from a theoretical stand point but with little support from experimental data. In shrub-dominated rangeland communities, this VDSH concept implies that spatial distribution of vegetation can be used to model: (1) the level of hillslope dissection into concentrated flow and sheet flow areas and (2) the magnitude of sediment entrapment (deposition) expected from a given vegetation spatial arrangement. In this study, we developed a methodology to test these two hypotheses and derive practical equations for modeling purposes. From a series of rainfall / runoff experiments on naturally vegetated shrubland erosion plots, flow concentration and erosion / deposition processes were quantified using a combination of sediment yield data and high resolution microtopographic changes detected with advance 3D reconstruction technologies (lidar and photogrammetry). This study is expected to produce for the first time (1) predictive equations for spatial frequency of flow concentration pathways in shrub-dominated rangeland communities and (2) equations for sediment delivery ratio, a measure of the portion of eroded sediment that reaches the hillslope outlet as a function of vegetation spatial arrangement.

  10. Effect of feeding in 30-day bioaccumulation assays using Hyalella azteca in fluoranthene-dosed sediment

    SciTech Connect

    Harkey, G.A.; Driscoll, S.K.; Landrum, P.F.

    1997-04-01

    Current protocols for conducting freshwater sediment bioaccumulation tests recommend that food not be added to exposures, whereas toxicity tests require food addition. To determine effects of adding food on exposure, 30-d sediment exposures were conducted with Hyalella azteca to sediment dosed with four fluoranthene concentrations. Accumulation was significantly greater in fed versus nonfed animals at all dose levels after 96 h of exposure and continued to be greater after 30 d in the low dose levels. At sediment concentrations above 478 nmol/g dry weight, survival of unfed animals dropped to 34% after 30 d. After 30 d of exposure, growth and reproduction were observed in fed animals exposed to sediment 10-d studies reported in the literature using sediment with comparable organic carbon concentrations. Samples of sediment in exposure breakers taken from the sediment-water interface (flocculant layer) and 1 to 2 cm below the interface had large differences in fluoranthene and organic carbon concentrations. The concentration of fluoranthene was 2 to 10 times greater in the flocculant layer, the area inhabited by H. azteca, compared to the deeper sediment. These data raise questions concerning the interpretation of standard toxicity and bioaccumulation tests when food is routinely added.

  11. 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.

  12. Effects of cadmium-enriched sediment on fish and amphibian embryo-larval stages

    SciTech Connect

    Francis, P.C.; Birge, W.J.; Black, J.A.

    1984-08-01

    Aquatic toxicity tests were conducted to evaluate the effects of cadmium-enriched sediment on embryo-larval stages of the goldfish (Carassius auratus), leopard frog (Rana pipiens), and largemouth bass (Micropterus salmoides). Natural stream sediment was collected and enriched with cadmium to nominal concentrations of 1.0, 10.0, 100, and 1000 mg/kg. Enriched sediments were placed in Pyrex dishes and covered with 350 ml of reconstituted water. Fertilized eggs were placed in the dishes and maintained through 4 days posthatching, giving a total exposure time of 6 to 7 days. For all tests the cadmium concentrations ranged from 1.1 to 76.5 micrograms/liter in water above sediments containing 1 to 1000 mg Cd/kg, respectively. Although low frequencies of mortality were observed in all tests, goldfish, leopard frog, and bass exposed to sediments enriched to 1000 mg Cd/kg accumulated 4.61, 12.55, and 60.0 micrograms Cd/g, respectively. No significant correlations were found between mortality of the goldfish and leopard frog and the cadmium concentrations in either water or sediment. However, all three species showed strong correlations between cadmium concentrations in water and tissue, sediment and tissue, and water and sediment. Tissue cadmium concentrations were related to the length of time test organisms were in direct contact with cadmium-enriched sediment.

  13. An evaluation of selenium concentrations in water, sediment, invertebrates, and fish from the Solomon River Basin.

    PubMed

    May, Thomas W; Fairchild, James F; Petty, Jim D; Walther, Michael J; Lucero, Jeff; Delvaux, Mike; Manring, Jill; Armbruster, Mike

    2008-02-01

    The Solomon River Basin is located in north-central Kansas in an area underlain by marine geologic shales. Selenium is an indigenous constituent of these shales and is readily leached into the surrounding groundwater. Portions of the Basin are irrigated primarily through the pumping of selenium-contaminated groundwater from wells onto fields in agricultural production. Water, sediment, macroinvertebrates, and fish were collected from various sites in the Basin in 1998 and analyzed for selenium. Selenium concentrations were analyzed spatially and temporally and compared to reported selenium toxic effect thresholds for specific ecosystem components: water, sediments, food-chain organisms, and wholebody fish. A selenium aquatic hazard assessment for the Basin was determined based on protocol established by Lemly. Throughout the Basin, water, macroinvertebrate, and whole fish samples exceeded levels suspected of causing reproductive impairment in fish. Population structures of several fish species implied that successful reproduction was occurring; however, the influence of immigration of fish from low-selenium habitats could not be discounted. Site-specific fish reproduction studies are needed to determine the true impact of selenium on fishery resources in the Basin. PMID:17587192

  14. An evaluation of selenium concentrations in water, sediment, invertebrates, and fish from the Solomon River Basin

    USGS Publications Warehouse

    May, T.W.; Fairchild, J.F.; Petty, J.D.; Walther, M.J.; Lucero, J.; Delvaux, M.; Manring, J.; Armbruster, M.

    2008-01-01

    The Solomon River Basin is located in north-central Kansas in an area underlain by marine geologic shales. Selenium is an indigenous constituent of these shales and is readily leached into the surrounding groundwater. Portions of the Basin are irrigated primarily through the pumping of selenium-contaminated groundwater from wells onto fields in agricultural production. Water, sediment, macroinvertebrates, and fish were collected from various sites in the Basin in 1998 and analyzed for selenium. Selenium concentrations were analyzed spatially and temporally and compared to reported selenium toxic effect thresholds for specific ecosystem components: water, sediments, food-chain organisms, and wholebody fish. A selenium aquatic hazard assessment for the Basin was determined based on protocol established by Lemly. Throughout the Basin, water, macroinvertebrate, and whole fish samples exceeded levels suspected of causing reproductive impairment in fish. Population structures of several fish species implied that successful reproduction was occurring; however, the influence of immigration of fish from low-selenium habitats could not be discounted. Site-specific fish reproduction studies are needed to determine the true impact of selenium on fishery resources in the Basin. ?? Springer Science+Business Media B.V. 2007.

  15. Passive sampling methods for contaminated sediments: Scientific rationale supporting use of freely dissolved concentrations

    PubMed Central

    Mayer, Philipp; Parkerton, Thomas F; Adams, Rachel G; Cargill, John G; Gan, Jay; Gouin, Todd; Gschwend, Philip M; Hawthorne, Steven B; Helm, Paul; Witt, Gesine; You, Jing; Escher, Beate I

    2014-01-01

    Passive sampling methods (PSMs) allow the quantification of the freely dissolved concentration (Cfree) of an organic contaminant even in complex matrices such as sediments. Cfree is directly related to a contaminant's chemical activity, which drives spontaneous processes including diffusive uptake into benthic organisms and exchange with the overlying water column. Consequently, Cfree provides a more relevant dose metric than total sediment concentration. Recent developments in PSMs have significantly improved our ability to reliably measure even very low levels of Cfree. Application of PSMs in sediments is preferably conducted in the equilibrium regime, where freely dissolved concentrations in the sediment are well-linked to the measured concentration in the sampler via analyte-specific partition ratios. The equilibrium condition can then be assured by measuring a time series or a single time point using passive samplers with different surface to volume ratios. Sampling in the kinetic regime is also possible and generally involves the application of performance reference compounds for the calibration. Based on previous research on hydrophobic organic contaminants, it is concluded that Cfree allows a direct assessment of 1) contaminant exchange and equilibrium status between sediment and overlying water, 2) benthic bioaccumulation, and 3) potential toxicity to benthic organisms. Thus, the use of PSMs to measure Cfree provides an improved basis for the mechanistic understanding of fate and transport processes in sediments and has the potential to significantly improve risk assessment and management of contaminated sediments. Integr Environ Assess Manag 2014;10:197–209. © 2014 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of SETAC. PMID:24288295

  16. Estimation of Bacterial Nitrate Reduction Rates at In Situ Concentrations in Freshwater Sediments

    PubMed Central

    Hordijk, Cornelis A.; Snieder, Marchel; van Engelen, Johannes J. M.; Cappenberg, Thomas E.

    1987-01-01

    A method was developed to follow bacterial nitrate reduction in freshwater sediments by using common high-performance liquid chromatographic equipment. The low detection limit (14 pmol) of the method enabled us to study concentration profiles and reaction kinetics under natural conditions. Significant nitrate concentrations (1 to 27 μM) were observed in the sediment of Lake Vechten during the nonstratified period; the concentration profiles showed a successive depletion of oxygen, nitrate, and sulfate with depth. The profiles were restricted to the upper 3 cm of the sediment which is rich in organics and loosely structured. Nitrate reduction in the sediment-water interface followed first-order reaction kinetics at in situ concentrations. Remarkably high potential nitrate-reducing activity was observed in the part of the sediment in which nitrate did not diffuse. This activity was also observed throughout the whole year. Estimates of Km varied between 17 and 100 μM and Vmax varied between 7.2 and 36 μmol cm−3 day−1 for samples taken at different depths. The diffusion coefficient of nitrate ([10 ± 0.4] × 10−6 cm2 s−1) across the sediment-water interface was estimated by a constant-source technique and applied to a mathematical model to estimate the net nitrate reduction during the nonstratified period. In this period, observed nitrate reduction rates by the model, 0.2 to 0.4 mmol m−2 day−1, were lower than those found for oxygen (27 mmol m−2 day−1) and sulfate (0.4 mmol m−2 day−1). During the summer stratification, nitrate was absent in the sediment and reduction could not be estimated by the model. PMID:16347270

  17. The effect of biological and physical disturbances on the transport of arsenic from contaminated estuarine sediments

    NASA Astrophysics Data System (ADS)

    Riedel, Gerhardt F.; Sanders, James G.; Osman, Richard W.

    1987-12-01

    From the distribution of dissolved and solid arsenic species in a contaminated estuarine sediment and measured rates of flux of the various arsenic species we propose an empirical model for the cycling of arsenic between sediments and water column. The chemical form of arsenic in the sediment was largely determined by the redox state of the sediment. Arsenite was the dominant dissolved and solid species in the deeper reduced sediment, and arsenate was dominant in the oxidized surface layer. Arsenite in the interstitial water diffused toward the surface layer, where it was mostly oxidized to arsenate prior to leaving the sediments. Some arsenate adsorbed to the surface sediments and produced a surface layer enriched in arsenic. Small concentrations of methyl and dimethyl arsenic were produced in the sediments, and these also diffused into the overlying water. Nereis succinea, a burrowing polychaete, affected distribution and flux of arsenic from the sediments by its production of irrigated burrows. These burrows increased both the effective surface area of the sediment and the diffusion of arsenic by a factor of five. When the relative effects of the activities of Nereis succinea and physical resuspension are compared, results indicate that although physical resuspension can produce large pulses of materials from contaminated sediments, continuous biological activity is likely to be more important in the mobilization of contaminants from sediments in many estuarine environments.

  18. Analysis of suspended-sediment concentrations and discharges at four long-term sediment stations in central and southern Illinois, 1975-92 water years

    USGS Publications Warehouse

    Terrio, Paul J.

    1996-01-01

    The U.S. Geological Survey and the U.S. Army Corps of Engineers, St. Louis District, have jointly operated four sediment stations in central and southern Illinois since May 1975--Illinois River at Valley City, Kaskaskia River at Cooks Mills, Kaskaskia River near Venedy Station, and Big Muddy River at Murphysboro. A comprehensive analysis of the historical data from these sediment stations was done to determine changes in the concentrations or amounts of suspended sediment transported in the streams. Generally, the highest suspended-sediment concentrations were found in the Illinois River at Valley City (the station with the largest drainage area), and the lowest concentrations were in the Kaskaskia River at Cooks Mills (the station with the smallest drainage area). Suspended-sediment concentrations were typically high in the spring and summer (March through August) and low in the fall or winter (September through February). The seasonal Kendall test for trends indicated a statistically significant downward trend in suspended-sediment concentrations at three of the sediment stations, including a downward trend of 5.50 milligrams per liter per year in the Illinois River at Valley City. Median suspended-sediment discharges at the four sediment stations ranged from 47.1 to 3,260 tons per day and corresponded to the size of the drainage areas. The largest median suspended sediment yield, 0.12 tons per square mile per day, was in the Illinois River at Valley City. Suspended-sediment discharges during the spring were larger than during other seasons. The seasonal Kendall test for trends indicated a statistically significant downward trend in suspended sediment discharges at two of the sediment stations (Kaskaskia River at Cooks Mills and Big Muddy River at Murphysboro).

  19. Estimation of suspended sediment concentration from turbidity measurements for agrarian watersheds of Navarre (Spain)

    NASA Astrophysics Data System (ADS)

    Madrona, Cecilia; Campo-Bescós, Miguel A.; Giménez, Rafael

    2016-04-01

    Studies of soil erosion at watershed scales have addressed this phenomenon from a holistic perspective, linking and prioritizing the dominant influence of the different factors involved in this complex process. Thus, the pattern of sediment transport in a watershed is an excellent indicator of the type and intensity of the dominant erosion processes as well as of the relationships between precipitation, infiltration and runoff. An optimal characterization of the dynamics of sediment requires reliable measurements and recording of the suspended sediment concentration (SSC) at the watershed outlet at a small time scale (minutes) since SSC normally fluctuates rapidly during storm events. But the latter is economically feasible only through indirect measurements; for example, by using turbidimeter. In fact, turbidity is a common subrogate of suspended sediment concentration; but for this purpose it is necessary first to define a suitable (empirical) turbidity-SSC model. But this is not an easy task since the wide range of possible suspended particles of different nature and composition (e.g., silt, clay, organic matter and microorganisms) often lead to a weak association between SSC and turbidity. In Navarre (Spain), soil erosion is an important problem affecting agricultural land. For this reason, the local Government owns and maintains a network of four experimental watersheds to assess the impact on the environment of typical agrarian activities. So that, the amount of sediment and solutes evacuated at the exit of each watershed has been recorded, along with other relevant hydrological and meteorological data. Furthermore, turbidity has been measured every ten minutes. But turbidity-SSC model - determined from average daily data of SSC- currently in use is unsatisfactory, especially for spring and summer events. The aim of this study is to find an appropriate turbidity-SSC relationship for (each of) the agrarian experimental watersheds of Navarre. Regression

  20. Predicting pollutant concentrations in the water column during dredging operations: Implications for sediment quality criteria.

    PubMed

    Wasserman, Julio Cesar; Wasserman, Maria Angélica V; Barrocas, Paulo Rubens G; Almeida, Aline Mansur

    2016-07-15

    The development of new dredging techniques that can reduce, or at least predict, the environmental impacts, is in high demand by governments in developing countries. In the present work, a new methodology was developed, to evaluate the level of metals contamination (i.e. cadmium, lead and zinc) of the water column, during a dredging operation. This methodology was used to evaluate the impacts of the construction of a new maritime terminal in Sepetiba Bay, Brazil. The methodology quantifies the amount of resuspended sediments and calculates the expected contaminants concentrations in the water column. The results indicated that sediment quality criteria were not compatible with water quality criteria, because the dredging of contaminated sediments does not necessarily yield contaminated water. It is suggested that the use of sediment quality criteria for dredging operations might be abandoned, and the methodology presented in this study applied to assess dredging's environmental impacts, predicting water contamination levels. PMID:27216043

  1. The effects of wildfire on the sediment yield of a coastal California watershed

    USGS Publications Warehouse

    Warrick, J.A.; Hatten, J.A.; Pasternack, G.B.; Gray, A.B.; Goni, M.A.; Wheatcroft, R.A.

    2012-01-01

    The occurrence of two wildfires separated by 31 yr in the chaparral-dominated Arroyo Seco watershed (293 km) of California provides a unique opportunity to evaluate the effects of wildfire on suspended-sediment yield. Here, we compile discharge and suspended-sediment sampling data from before and after the fires and show that the effects of the postfire responses differed markedly. The 1977 Marble Cone wildfire was followed by an exceptionally wet winter, which resulted in concentrations and fluxes of both fine and coarse suspended sediment that were ˜35 times greater than average (sediment yield during the 1978 water year was 11,000 t/km2/yr). We suggest that the combined 1977–1978 fire and flood had a recurrence interval of greater than 1000 yr. In contrast, the 2008 Basin Complex wildfire was followed by a drier than normal year, and although suspended-sediment fluxes and concentrations were significantly elevated compared to those expected for unburned conditions, the sediment yield during the 2009 water year was less than 1% of the post–Marble Cone wildfire yield. After the first postfire winters, sediment concentrations and yield decreased with time toward prefire relationships and continued to have significant rainfall dependence. We hypothesize that the differences in sediment yield were related to precipitation-enhanced hillslope erosion processes, such as rilling and mass movements. The millennial-scale effects of wildfire on sediment yield were explored further using Monte Carlo simulations, and these analyses suggest that infrequent wildfires followed by floods increase long-term suspended-sediment fluxes markedly. Thus, we suggest that the current approach of estimating sediment yield from sediment rating curves and discharge data—without including periodic perturbations from wildfires—may grossly underestimate actual sediment yields.

  2. Areal distribution and concentrations of contaminants of concern in surficial streambed and lakebed sediments, Lake Erie-Lake Saint Clair Drainages, 1990-97

    USGS Publications Warehouse

    Rheaume, S.J.; Button, D.T.; Myers, D.N.; Hubbell, D.L.

    2001-01-01

    Concerns about elevated concentrations of contaminants such as polychlorinated biphenyls and mercury in aquatic bed sediments throughout the Great Lakes Basin have resulted in a need for better understanding of the scope and severity of the problem. Various organochlorine pesticides, polychlorinated biphenyls, trace metals, and polycyclic aromatic hydrocarbons are a concern because of their ability to persist and accumulate in aquatic sediments and their association with adverse aquatic biological effects. The areal distribution and concentrations in surficial bed sediments of 20 contaminants of concern with established bed-sediment-toxicity guidelines were examined in relation to their potential effects on freshwater aquatic biota. Contaminants at more than 800 sampling locations are characterized in this report. Surficial bed-sediment-quality data collected from 1990 to 1997 in the Lake Erie?Lake Saint Clair Drainages were evaluated to reflect recent conditions. In descending order, concentrations of total polycyclic aromatic hydrocarbons, phenanthrene, total polychlorinated biphenyls, chrysene, benz[a]anthracene, benzo[a]pyrene, cadmium, lead, zinc, arsenic, and mercury were the contaminants that most commonly exceeded levels associated with probable adverse effects on aquatic benthic organisms. The highest concentrations of most of these contaminants in aquatic bed sediments are confined to the 12 specific geographic Areas of Concern identified in the 1987 Revisions to the Great Lakes Water Quality Agreement of 1972. An exception is arsenic, which was detected at concentrations exceeding threshold effect levels at many locations outside Areas of Concern.

  3. Effects of drainage on water, sediment and biota

    USGS Publications Warehouse

    Engberg, Richard A.; Sylvester, Marc A.; Feltz, Herman R.

    1991-01-01

    The U.S. Department of the Interior started a program in 1985 to identify effects of irrigation-induced trace constituents in water, bottom sediment and biota. The program was developed in response to concerns that contamination similar to that found in 1983 at Kesterson Reservoir in California might exist elsewhere. Studies are complete or underway for 26 sites in 15 western States. Selenium is the trace constituent most often found at elevated concentrations in all media. Maximum selenium concentrations in fish from 9 of 20 areas exceeded the threshold concentration for adverse reproductive effects. Maximum selenium concentrations in bird livers from 11 areas exceeded the level at which embryonic deformities are likely; deformed birds were observed in 5 areas. Trace constituent problems may be anticipated if geologic sources such as marine shales occur in an irrigation project area. The potential for problems is increased if closed basins or sinks are present.

  4. Heavy metal concentrations in water, suspended matter, and sediment from Gökova Bay, Turkey.

    PubMed

    Balkis, Nuray; Aksu, Abdullah; Okuş, Erdoğan; Apak, Reşat

    2010-08-01

    The contents of heavy metals (Fe, Mn, Pb, Cu, Cd, and Hg) dissolved in water and suspended solids of Gökova Bay--partly and fully sampled in 2005 and 2006, respectively--are quite higher than the average values encountered in uncontaminated sea water. The high concentrations are associated with terrestrial inputs from the mining zones and anthropogenic (domestic+industrial) sources. Moreover, the distribution of Fe and Cu is affected by primary production because these elements function as nutrients in biological activities. The Cr, Ni, and Fe concentrations of surface sediments are above the shale average. The Cr and Ni contents of surface sediments representative of river mouths strongly correlate with total phosphorus contents. In a sulfide-poor environment, Pb and Cu were concentrated at a higher ratio in surface sediments than Cd, probably due to higher stabilities of their surface complexes with amorphous iron oxides and clay minerals existing as major components in the sediments. The exceptional enrichment of Zn may be attributed to double oxide formation with amorphous iron oxides in sediments. The high metal values are most probably caused by terrestrial inputs from anthropogenic sources and the mining zones at the southeast part of the bay. The Al, Mn, Pb, Cu, Zn, and Hg contents are below the shale average. The low values have possibly originated from the coarse-grained sandy sediments having a low affinity for metals. There are no distinct differences in the metal distributions in water and suspended matter between the years 2005 and 2006 in the bay, probably due to low sedimentation rates. PMID:19565345

  5. A catchment-wide assessment of bed sediment metal concentrations in the first industrial city

    NASA Astrophysics Data System (ADS)

    Hurley, Rachel; Rothwell, James; Woodward, Jamie

    2016-04-01

    Manchester is often heralded as the 'first industrial city'. Rapid industrialisation in the 18th and 19th centuries saw vast quantities of fine-grained sediments (e.g. boiler ash and cinders) and contaminants (e.g. dyes, bleaches, and chemicals) deposited into the river channels of the Irwell and Mersey in a manner largely unchecked until the 1970s. Although water quality has improved in recent decades, there is a paucity of information on fluvial sediment quality and the extent to which a legacy of historical contamination persists in the contemporary river network. Forty five sites were sampled across the Irwell and Mersey catchments during low flow conditions in spring/summer 2015. Fine-grained bed sediment was collected using the Lambert and Walling (1988) method. Wet sieving was used to isolate the <63 μm fraction for geochemical analysis. Heavy metal concentrations were obtained via XRF with a particular focus on As, Cr, Cu, Pb and Zn. In order to explore controls on sediment-associated metal concentrations, additional characteristics of the bed sediment were also investigated, including particle size and organic matter content. Enrichment factors, based on mean concentrations obtained from pre-industrial floodplain deposits, were calculated. The enrichment factors reveal severe or very severe metal contamination across the whole catchment, including the headwater basins. Relationships between bed sediment quality and hotspots of historic industrial activity have been examined - these reveal complex spatial patterns associated with the high number and variety of historic contaminant inputs. These data form the first baseline assessment and will be used within a larger project investigating the impact of extreme hydrological events on bed sediment quality and transfer in these catchments.

  6. Present and Reference Concentrations and Yields of Suspended Sediment in Streams in the Great Lakes Region and Adjacent Areas

    USGS Publications Warehouse

    Robertson, Dale M.; Saad, David A.; Heisey, Dennis M.

    2006-01-01

    In-stream suspended sediment and siltation and downstream sedimentation are common problems in surface waters throughout the United States. The most effective way to improve surface waters impaired by sediments is to reduce the contributions from human activities rather than try to reduce loadings from natural sources. Total suspended sediment/solids (TSS) concentration data were obtained from 964 streams in the Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy River Basins from 1951 to 2002. These data were used to estimate median concentrations, loads, yields, and volumetrically (flow) weighted (VW) concentrations where streamflow data were available. SPAtial Regression-Tree Analysis (SPARTA) was applied to land-use-adjusted (residualized) TSS data and environmental-characteristic data to determine the natural factors that best described the distribution of median and VW TSS concentrations and yields and to delineate zones with similar natural factors affecting TSS, enabling reference or natural concentrations and yields to be estimated. Soil properties (clay and organic-matter content, erodibility, and permeability), basin slope, and land use (percentage of agriculture) were the factors most strongly related to the distribution of median and VW TSS concentrations. TSS yields were most strongly related to amount of precipitation and the resulting runoff, and secondarily to the factors related to high TSS concentrations. Reference median TSS concentrations ranged from 5 to 26 milligrams per liter (mg/L), reference median annual VW TSS concentrations ranged from 10 to 168 mg/L, and reference TSS yields ranged from about 980 to 90,000 kilograms per square kilometer per year. Independent streams (streams with no overlapping drainage areas) with TSS data were ranked by how much their water quality exceeded reference concentrations and yields. Most streams exceeding reference conditions were in the central part of the study area, where agricultural activities

  7. Bioaccumulation and molecular effects of sediment-bound metals in zebrafish embryos.

    PubMed

    Redelstein, R; Zielke, H; Spira, D; Feiler, U; Erdinger, L; Zimmer, H; Wiseman, S; Hecker, M; Giesy, J P; Seiler, T-B; Hollert, H

    2015-11-01

    Predicting the bioavailability and effects of metals in sediments is of major concern in context with sediment risk assessment. This study aimed to investigate the bioavailability and molecular effects of metals spiked into riverine sediments to zebrafish (Danio rerio) embryos. Embryos were exposed to a natural and an artificial sediment spiked with cadmium (Cd), copper (Cu), nickel (Ni) and zinc (Zn) individually or as a mixture at concentrations ranging from 150 to 3000 mg/kg dry weight (dw) over 48 h, and uptake of metals was determined. Furthermore, transcript abundances of the metallothioneins MT1 and MT2, the metal-responsive element-binding transcription factor (MTF) and the genes sod1, hsp70 and hsp90α1 were measured as indicators of metal-induced or general cellular stress. D. rerio embryos accumulated metals from sediments at concentrations up to 100 times greater than those spiked to the sediment with the greatest bioaccumulation factor (BAF) for Cu from artificial sediment (275.4 ± 41.9 (SD)). Embryos accumulated greater concentrations of all metals from artificial than from natural sediment, and accumulation was greater when embryos were exposed to individual metals than when they were exposed to the mixture. Exposure of embryos to Zn or the mixture exhibited up to 30-fold greater transcript abundances of MT1, MT2 and hsp70 compared to controls which is related to significant uptake of Zn from the sediment. Further changes in transcript abundances could not be related to a significant uptake of metals from sediments. These studies reveal that metals from spiked sediments are bioavailable to D. rerio embryos directly exposed to sediments and that the induction of specific genes can be used as biomarkers for the exposure of early life stages of zebrafish to metal-contaminated sediments. PMID:26354112

  8. Comparing polychlorinated biphenyl concentrations and patterns in the Saginaw River using sediment, caged fish, and semipermeable membrane devices

    USGS Publications Warehouse

    Echols, K.R.; Gale, R.W.; Schwartz, T.R.; Huckins, J.N.; Williams, L.L.; Meadows, J.C.; Morse, D.; Petty, J.D.; Orazio, C.E.; Tillitt, D.E.

    2000-01-01

    Three techniques of assessing bioavailable polychlorinated biphenyls (PCBs) in the Saginaw River, MI, were compared: sediments, caged fish, and semipermeable membrane devices (SPMDs). SPMDs and caged fish were placed in the river for 28 days at five sites where sediments were also sampled. The samples were analyzed for PCB congeners to determine concentrations and patterns. Total PCB concentrations ranged from 33 to 280 ng/g (dry weight) in sediments, 46 to 290 ng/g (wet weight) in caged fish, and 77 to 790 ng/g in SPMDs. Previously reported rates of PCB accumulation by SPMDs were used to estimate aqueous concentrations from the PCB concentrations detected in the SPMDs. Sediment-water partition coefficients were used to estimate aqueous PCB concentrations from sediment. Steady-state bioconcentration factors and depuration rate constants were used to estimate dissolved PCB concentrations from caged channel catfish. Relative PCB patterns from the SPMDs, caged fish, and sediment were compared using principal components analysis. SPMD and sediment samples provide complementary information. Sediments reflect long-term accumulation and weathering, while SPMDs integrate water concentrations only during the sampling period. Because of higher water solubilities of lower-chlorinated PCBs these predominate in the SPMDs as compared to in the fish and sediments. Contaminant profile differences between caged fish and SPMDs are likely due to metabolism and depuration of certain PCB congeners by fish.Three techniques of assessing bioavailable polychlorinated biphenyls (PCBs) in the Saginaw River, Ml, were compared: sediments, caged fish, and semipermeable membrane devices (SPMDs). SPMDs and caged fish were placed in the river for 28 days at five sites where sediments were also sampled. The samples were analyzed for PCB congeners to determine concentrations and patterns. Total PCB concentrations ranged from 33 to 280 ng/g (dry weight) in sediments, 46 to 290 ng/g (wet weight) in

  9. A step decrease in sediment concentration in a highly modified tidal river delta following the 1983 El Niño floods

    USGS Publications Warehouse

    Hestir, Erin L.; Schoellhamer, David H.; Morgan-King, Tara; Ustin, Susan L.

    2013-01-01

    Anthropogenic activities in watersheds can have profound effects on sediment transport through river systems to estuaries. Disturbance in a watershed combined with alterations to the hydro-climatologic regime may result in changes to the sediment flux, and exacerbate the impacts of extreme events (such as large-magnitude floods) on sediment transport. In the San Francisco Estuary, suspended sediment has been declining over the past 30 years as a result of declining sediment supply, contributing to dramatic changes in the ecology and geomorphology of the estuary. However, the decline has not been gradual. Recent observations of an abrupt decrease in suspended sediments in the San Francisco Bay have been explained by a model that suggests that the step change has occurred due to exceedance of a sediment regulation threshold that triggered the change from a sediment transport regime to a supply-limited system. We investigated structural changes in the historical record of total suspended solids (TSS) concentration measured in the upper estuary to verify the model predictions. TSS in the upper estuary exhibited an abrupt step decrease in 1983 corresponding to the record-high winter and summer flows from the 1982 to 1983 El Niño event. After this step change, TSS concentrations had a significant declining trend despite subsequent near-record high flows. The abrupt change in TSS followed by the declining trend provides evidence for the hypothesis of sediment supply limitation in the San Francisco Estuary.

  10. Are Stream and Ditch P Concentrations Related to Sediment P Status and Land Use?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High P levels in surface waters can cause algae blooms and increase water treatment costs in reservoirs used for potable water. Sediments can buffer soluble P concentrations in ditches and streams that feed into these reservoirs. Our study area included ditches and streams that serve as the headwate...

  11. Tidal river sediments in the Washington, D.C. area. 111 Biological effects associated with sediment contamination

    SciTech Connect

    Schlekat, C.E.; McGee, B.L.; Boward, D.M.

    1994-06-01

    Sediment toxicity and benthic marcroinvertebrate community structure were measured as one component of a study conceived to determine the distribution and effect of sediment contamination in tidal freshwater portions of the Potomac and Anacostia rivers in the Washington, D.C., area. Samples were collected at 15 sites. Analyses included a partial life cycle (28 d) whole sediment test using the amphipod Hyalella azteca (Talitridae) and an assessment of benthic community structure. Survival and growth (as estimated by amphipod length) were experimental endpoints for the toxicity test. Significant mortality was observed in 5 to 10 sites in the lower Anacostia River basin and at the main channel Potomac River site. Sublethal toxicity, as measured by inhibition of amphipod growth, was not observed. Toxicity test results were in general agreement with synoptically measured sediment contaminant concentrations. Porewater total ammonia (NH{sub 3} + NH{sub 4}{sup +}) appears to be responsible for the toxicity of sediments from the Potomac River, while correlation analysis and simultaneously extracted metals: acid volatile sulfide (SEM:AVA) results suggest that the toxicity associated with Anacostia River sediments was due to organic compounds. Twenty-eight macroinvertebrate taxa were identified among all sites, with richness varying from 5 to 17 taxa per site. Groups of benthic assemblages identified by group-average cluster analysis exhibited variable agreement with sediment chemical and sediment toxicity results. Integration of toxicological, chemical, and ecological components suggests that adverse environmental effects manifest in lower Anacostia River benthos result from chemical contamination of sediment. 37 refs., 2 figs., 7 tabs.

  12. Analysis of heavy metals concentration in water and sediment in the Hara biosphere reserve, southern Iran.

    PubMed

    Nowrouzi, Mohsen; Mansouri, Borhan; Nabizadeh, Sahar; Pourkhabbaz, Alireza

    2014-02-01

    This study determined the concentration of heavy metals (Al, Cr, Cu, and Zn) in water and sediments at nine sites in the Hara biosphere reserve of southern Iran during the summer and winter 2010. Determination of Al, Cr, Cu, and Zn in water was carried out by graphite furnace atomic absorption spectrometer (Shimadzu, AA 610s) and in sediment by flame atomic absorption spectrometer (Perkin Elmer, AA3030). Results showed that the heavy metal concentrations in the water samples decreased in the sequence of Zn > Al > Cu > Cr, while in sediment samples were Cr > Zn > Cu > Al. Data analysis indicated that with the exception of Al, there was a Pearson's correlation coefficient between pH and Cu, Zn, and Cr at α = 0.01, 0.05, and 0.001 in sediment (in winter), respectively. There were also significant differences between heavy metals of Cr, Cu, and Zn during the two seasons (p < 0.001) in the water and sediment. PMID:22740619

  13. Adapting SWAT hillslope erosion model to predict sediment concentrations and yields in large Basins.

    PubMed

    Vigiak, Olga; Malagó, Anna; Bouraoui, Fayçal; Vanmaercke, Matthias; Poesen, Jean

    2015-12-15

    The Soil and Water Assessment Tool (SWAT) is used worldwide for water quality assessment and planning. This paper aimed to assess and adapt SWAT hillslope sediment yield model (Modified Universal Soil Loss Equation, MUSLE) for applications in large basins, i.e. when spatial data is coarse and model units are large; and to develop a robust sediment calibration method for large regions. The Upper Danube Basin (132,000km(2)) was used as case study representative of large European Basins. The MUSLE was modified to reduce sensitivity of sediment yields to the Hydrologic Response Unit (HRU) size, and to identify appropriate algorithms for estimating hillslope length (L) and slope-length factor (LS). HRUs gross erosion was broadly calibrated against plot data and soil erosion map estimates. Next, mean annual SWAT suspended sediment concentrations (SSC, mg/L) were calibrated and validated against SSC data at 55 gauging stations (622 station-years). SWAT annual specific sediment yields in subbasin reaches (RSSY, t/km(2)/year) were compared to yields measured at 33 gauging stations (87station-years). The best SWAT configuration combined a MUSLE equation modified by the introduction of a threshold area of 0.01km(2) where L and LS were estimated with flow accumulation algorithms. For this configuration, the SSC residual interquartile was less than +/-15mg/L both for the calibration (1995-2004) and the validation (2005-2009) periods. The mean SSC percent bias for 1995-2009 was 24%. RSSY residual interquartile was within +/-10t/km(2)/year, with a mean RSSY percent bias of 12%. Residuals showed no bias with respect to drainage area, slope, or spatial distribution. The use of multiple data types at multiple sites enabled robust simulation of sediment concentrations and yields of the region. The MUSLE modifications are recommended for use in large basins. Based on SWAT simulations, we present a sediment budget for the Upper Danube Basin. PMID:26356993

  14. Effect of feeding in 30-day bioaccumulation assays using Hyalella azteca in fluoranthene-dosed sediment

    SciTech Connect

    Harkey, G.A.; Landrum, P.F.

    1995-12-31

    Current protocols for conducting freshwater sediment bioaccumulation tests require that food be added to exposures. To determine effects of adding food, 30-day bioaccumulation assays were conducted with H. azteca exposed to sediment dosed with four concentrations (0.05 to 1,267 nmol/g dry weight) of fluoranthene. Accumulation was significantly greater in fed versus non-fed animals at all dose levels after 96 and 240 hours of exposure and continued to be greater after 30 days in the low dose levels. At sediment concentrations above 634 nmol/g dw, survival of unfed animals dropped to 34% after 30 days, However, after 30 days, reproduction was observed in fed animals exposed to sediment concentrations > 16 times the expected LC50 calculated for fluoranthene in sediment. These data raise questions concerning the interpretation of standard toxicity and bioaccumulation tests when food is routinely added.

  15. Heavy metals' concentration in sediment, shrimp and two fish species from the northwest Persian Gulf.

    PubMed

    Monikh, Fazel Abdolahpur; Maryamabadi, Ammar; Savari, Ahmad; Ghanemi, Kamal

    2015-06-01

    The concentrations of heavy metals (cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn)) were measured in hepatopancreas and muscle of a commercial shrimp (Metapenaeus affinis), in the muscle, liver and gills of two fish species (Thryssa vitrirostris and Johnius belangerii) and in the sediment samples taken from the mouth of the Arvand river, Meleh estuary and Musa estuary in the northeast Persian Gulf. Concentration of heavy metals varied depending on different tissues, species and sampling sites. Liver of fish and hepatopancreas of shrimp exhibited higher metals' concentration than the other tissues. Generally, in the mouth of the Arvand river, the highest concentration of metals was found in benthic species; while in the mouth of Musa estuary, the highest level of the metals was found in pelagic fish species. Bioaccumulation factors were observed to follow the order: J. belangerii-liver-Cd > T. vitrirostris-liver-Pb > M. affinis-hepatopancreas-Zn >M. affinis-hepatopancreas-Cu >M. affinis- hepatopancreas-Ni. The analysed heavy metals were found in sediment samples at mean concentration in the sediment quality guideline proposed by National Oceanic and Atmospheric Administration (NOAA) and Regional Organization for the Protection of The Marine Environment (ROPME), except for Ni concentration in some cases. PMID:23406960

  16. PAH concentrations in lake sediment decline following ban on coal-tar-based pavement sealants in Austin, Texas

    USGS Publications Warehouse

    Van Metre, Peter C.; Mahler, Barbara J.

    2013-01-01

    Recent studies have concluded that coal-tar-based pavement sealants are a major source of polycyclic aromatic hydrocarbons (PAHs) in urban settings in large parts of the United States. In 2006, Austin, TX, became the first jurisdiction in the U.S. to ban the use of coal-tar sealants. We evaluated the effect of Austin’s ban by analyzing PAHs in sediment cores and bottom-sediment samples collected in 1998, 2000, 2001, 2012, and 2014 from Lady Bird Lake, the principal receiving water body for Austin urban runoff. The sum concentration of the 16 EPA Priority Pollutant PAHs (∑PAH16) in dated core intervals and surficial bottom-sediment samples collected from sites in the lower lake declined about 44% from 1998–2005 to 2006–2014 (means of 7980 and 4500 μg kg–1, respectively), and by 2012–2014, the decline was about 58% (mean of 3320 μg kg–1). Concentrations of ∑PAH16 in bottom sediment from two of three mid-lake sites decreased by about 71 and 35% from 2001 to 2014. Concentrations at a third site increased by about 14% from 2001 to 2014. The decreases since 2006 reverse a 40-year (1959–1998) upward trend. Despite declines in PAH concentrations, PAH profiles and source-receptor modeling results indicate that coal-tar sealants remain the largest PAH source to the lake, implying that PAH concentrations likely will continue to decline as stocks of previously applied sealant gradually become depleted.

  17. Uranium series isotopes concentration in sediments at San Marcos and Luis L. Leon reservoirs, Chihuahua, Mexico

    SciTech Connect

    Méndez-García, C.; Montero-Cabrera, M. E.; Renteria-Villalobos, M.; García-Tenorio, R.

    2008-01-01

    Spatial and temporal distribution of the radioisotopes concentrations were determined in sediments near the surface and core samples extracted from two reservoirs located in an arid region close to Chihuahua City, Mexico. At San Marcos reservoir one core was studied, while from Luis L. Leon reservoir one core from the entrance and another one close to the wall were investigated. ²³²Th-series, ²³⁸U-series, ⁴⁰K and ¹³⁷Cs activity concentrations (AC, Bq kg⁻¹) were determined by gamma spectrometry with a high purity Ge detector. ²³⁸U and ²³⁴U ACs were obtained by liquid scintillation and alpha spectrometry with a surface barrier detector. Dating of core sediments was performed applying CRS method to ²¹⁰Pb activities. Results were verified by ¹³⁷Cs AC. Resulting activity concentrations were compared among corresponding surface and core sediments. High ²³⁸U-series AC values were found in sediments from San Marcos reservoir, because this site is located close to the Victorino uranium deposit. Low AC values found in Luis L. Leon reservoir suggest that the uranium present in the source of the Sacramento – Chuviscar Rivers is not transported up to the Conchos River. Activity ratios (AR) ²³⁴U/²³⁸U and ²³⁸U/²²⁶Ra in sediments have values between 0.9–1.2, showing a behavior close to radioactive equilibrium in the entire basin. ²³²Th/²³⁸U, ²²⁸Ra/²²⁶Ra ARs are witnesses of the different geological origin of sediments from San Marcos and Luis L. Leon reservoirs.

  18. Uranium series isotopes concentration in sediments at San Marcos and Luis L. Leon reservoirs, Chihuahua, Mexico

    NASA Astrophysics Data System (ADS)

    Méndez-García, C.; Renteria-Villalobos, M.; García-Tenorio, R.; Montero-Cabrera, M. E.

    2014-07-01

    Spatial and temporal distribution of the radioisotopes concentrations were determined in sediments near the surface and core samples extracted from two reservoirs located in an arid region close to Chihuahua City, Mexico. At San Marcos reservoir one core was studied, while from Luis L. Leon reservoir one core from the entrance and another one close to the wall were investigated. 232Th-series, 238U-series, 40K and 137Cs activity concentrations (AC, Bq kg-1) were determined by gamma spectrometry with a high purity Ge detector. 238U and 234U ACs were obtained by liquid scintillation and alpha spectrometry with a surface barrier detector. Dating of core sediments was performed applying CRS method to 210Pb activities. Results were verified by 137Cs AC. Resulting activity concentrations were compared among corresponding surface and core sediments. High 238U-series AC values were found in sediments from San Marcos reservoir, because this site is located close to the Victorino uranium deposit. Low AC values found in Luis L. Leon reservoir suggest that the uranium present in the source of the Sacramento - Chuviscar Rivers is not transported up to the Conchos River. Activity ratios (AR) 234U/overflow="scroll">238U and 238U/overflow="scroll">226Ra in sediments have values between 0.9-1.2, showing a behavior close to radioactive equilibrium in the entire basin. 232Th/overflow="scroll">238U, 228Ra/overflow="scroll">226Ra ARs are witnesses of the different geological origin of sediments from San Marcos and Luis L. Leon reservoirs.

  19. Controls on Bacterial Concentrations in Sediment Grab Samples from the Hudson River Estuary

    NASA Astrophysics Data System (ADS)

    Batta, J.; Mailloux, B. J.; Nitsche, F. O.; Kenna, T. C.; Ferguson, A. S.; Cheung, J.; Layton, A.

    2010-12-01

    High levels of fecal bacteria resulting from sewage-related pollution are often present in the Hudson River Estuary. Die-off of the fecal bacteria in surface waters is relatively rapid but the fecal bacteria can also attach to particles and settle. It is known that fecal bacteria are present in the shallow sediments but controls on their distribution have not been closely examined. The goal of this work is to examine the relationship between the concentration of fecal indicator bacteria and sediment properties including estimates of sediment age. Forty sediment surface grabs were obtained from the Hudson River Estuary. Twenty samples were collected from near the George Washington Bridge (GWB) and twenty samples from a 15 mile transect near Hudson New York. Concentrations of fecal indicator bacteria were determined by the cultured based Enterolert and Colilert tests (Idexx Laboratories) and molecular based techniques for E. coli and Bacteroides. Sediments were analyzed for total metals, total organic carbon, grain size, and gamma emitting radionuclides including Beryllium-7, Lead-210, and Cesium-137. Enterococcus was present in the samples with a geometric mean of 88 cells/g and a range of 4 to 817 cells /g. Culturable E. Coli was present in the samples with a geometric mean of 168 cells /g and a range of 5 to 2247 cells /g. Enterococcus concentrations were significantly higher (p<0.05) in the northern transect. Molecular based concentrations were determined for the GWB samples and were significantly higher than culture based concentrations. Bacteroides was present in the samples with a geometric mean of 1.1x106 copies/g and a range of 3.9x104 to 4.7x106 copies /g. Molecular E. Coli was present in the samples with a geometric mean of 3.0x106 copies/g and a range of 8.7x104 to 8.9x107 copies /g. The results clearly show that a significant amount of fecal bacteria are present in the sediments. Simple linear correlations between bacterial concentrations and sediment

  20. Mud On the Move: Measuring Suspended Sediment Concentrations within Tidal Wetlands in the San Francisco Estuary

    NASA Astrophysics Data System (ADS)

    Callaway, J.; Ferner, M.; Lacy, J. R.; Schile, L. M.

    2014-12-01

    Supply of suspended sediment is critical for the development and sustainability of tidal wetlands. Suspended sediment concentration (SSC) is also a key parameter used in calibrating wetland accretion models, which aid in understanding restoration dynamics and projecting resilience to sea-level rise. Despite the importance of suspended sediment, few field studies have directly measured SSC within tidal wetlands, relying instead on measurements in adjacent waters or focusing on long-term rates of sediment accretion. We refined and tested a simple method for collecting SSC samples within wetlands on an incoming high tide, using siphon collectors. Bottles were positioned during low tide at set locations along transects extending away from either channels or the lower boundary of the vegetated wetland. This sampling protocol was developed collaboratively, with substantial input from local wetland managers and other stakeholders within the San Francisco Bay area and beyond. Simultaneously, we measured time series of SSC, water level, and tidal currents in the subtidal shallows, on the intertidal mudflats, and in two channels within the wetland. We observed significant sediment export during king tides in the wetland channels. Cumulative suspended sediment flux (SSF) over four days during the January 2014 king tides was approximately 10 tons/m of channel width, towards the bay. During neap tides SSF in the channels was directed landward but was lower in magnitude. Elevated velocities in the channels during ebb king tides suggest that resuspension within the channels, rather than erosion of the wetland, accounts for much of the bayward SSF. Within the wetland, SSC from the siphon samplers was highest at the bayward end of the cross-shore transects, indicating landward sediment flux. Taken together with long term accretion data which indicates sediment accumulation within the wetland, our results suggest that sediment is primarily supplied across the wetland-Bay interface

  1. Radionuclide concentrations in bed sediment and fish tissue within the Rio Grande drainage basin

    SciTech Connect

    Booher, J.L.; Fresquez, P.R.; Carter, L.F.; Gallaher, B.M.; Mullen, M.A.

    1998-02-01

    In 1992-93, Los Alamos National Laboratory collaborated with the U.S. Geological Survey in an effort to characterize radionuclide concentrations in bed sediment and fish tissue within the Rio Grande drainage basin from Colorado to Texas. Bed sediment was sampled from 18 locations for cesium ({sup 137}Cs), tritium ({sup 3}H), strontium ({sup 90}Sr), plutonium ({sup 238}Pu and {sup 239}Pu), americium ({sup 241}Am), total uranium ({sup tot}U) and alpha, beta, and gamma activity. Fish tissue was sampled from 12 locations for {sup 137}Cs, {sup 90}Sr, {sup 238}Pu, {sup 239}Pu and {sup tot}U.

  2. Sediment movement along the U.S. east coast continental shelf-II. Modelling suspended sediment concentration and transport rate during storms

    USGS Publications Warehouse

    Lyne, V.D.; Butman, B.; Grant, W.D.

    1990-01-01

    Long-term near-bottom wave and current observations and a one-dimensional sediment transport model are used to calculate the concentration and transport of sediment during winter storms at 60-80 m water depth along the southern flank of Georges Bank and in the Mid-Atlantic Bight. Calculations are presented for five stations, separated by more than 600 km alongshelf, that have different bottom sediment texture, bedforms and current conditions. A modified version of the sediment transport model presented by Grant and Glenn (1983, Technical Report to the American Gas Association), Glenn (1983, D.Sc. Thesis, M.I.T.), and Glenn and Grant (1987, Journal of Geophysical Research, 92, 8244-8264) is used to examine the influence of wave-current interaction, sediment stratification, and limitations on the erodibility of the bottom sediments on the concentration of sediment in the water column and on transport. Predicted suspended sediment concentrations are higher than observed, based on beam transmissometer measurements, unless an erosion limit of order a few millimeters for sediments finer than 94 ??m is imposed. The agreement between predicted and measured beam attenuation is better at stations that have significant amounts of silt plus clay in the surficial sediments than for stations with sandy sediments. Sediment concentrations during storms estimated by Moody et al. (1987, Continental Shelf Research, 7, 609-628) are within 50% of the model predictions. Sediment transport rates for sediments 94 ??m and finer are determined largely by the concentrations in the surficial sediment and the erosion depth limit. Large alongshelf transports in the direction of storm-driven currents are inferred for stations in the Mid-Atlantic Bight. During a 115-day period in winter 1979-1980, the net transport of sediment along the shelf was westward; benthic storms (defined as periods when the bottom wave stress exceeded the current stress by 2 dyn cm-2) occurred between 23 and 73% of the

  3. 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.

  4. 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.

  5. Comparison of methods for the concentration of suspended sediment in river water for subsequent chemical analysis

    USGS Publications Warehouse

    Horowltz, A.J.

    1986-01-01

    Centrifugation, settling/centrifugation, and backflush-filtration procedures have been tested for the concentration of suspended sediment from water for subsequent trace-metal analysis. Either of the first two procedures is comparable with in-line filtration and can be carried out precisely, accurately, and with a facility that makes the procedures amenable to large-scale sampling and analysis programs. There is less potential for post-sampling alteration of suspended sediment-associated metal concentrations with the centrifugation procedure because sample stabilization is accomplished more rapidly than with settling/centrifugation. Sample preservation can be achieved by chilling. Suspended sediment associated metal levels can best be determined by direct analysis but can also be estimated from the difference between a set of unfiltered-digested and filtered subsamples. However, when suspended sediment concentrations (<150 mg/L) or trace-metal levels are low, the direct analysis approach makes quantitation more accurate and precise and can be accomplished with simpler analytical procedures.

  6. Effect of phosphate and sediment bacteria on trichloroethylene dechlorination with zero valent iron.

    PubMed

    Min, Jee-Eun; Park, In Sun; Ko, Seokoh; Shin, Won Sik; Park, Jae-Woo

    2009-03-01

    The effects of sediment-isolated bacteria and phosphate on the efficacy of zero valent iron (ZVI) for the dechlorination of trichloroethylene (TCE) were examined in batch experiments. TCE (0.3 mM) and a constant concentration of sediment bacteria were simultaneously exposed to ZVI in the presence of 0 mmol, 15 mmol, and 30 mmol of phosphate. TCE profiles, starting from 0.3 mM to about 0.1 mM, exhibited two-phase of sorption kinetics at all three phosphate concentrations without the sediment bacteria. TCE removal was less and slower with phosphate in the system. With the sediment bacteria, however, more TCE was removed with the sediment bacteria than without it, unlike our initial hypothesis. With the sediment bacteria and phosphate, the concentration of ferrous (0.505 mM) ions was doubled that with phosphate only (0.271 mM). The sediment bacteria in this research, mainly Bacillus sp., could contribute to the long-term stability of ZVI reactivity for dechlorination of TCE in sediment. The sediment bacteria in this research could reduce the iron or chelate the evolved ferrous ions to retain the reducing reactivity of ZVI. PMID:19184703

  7. An evaluation of selenium concentrations in water, sediment, invertebrates, and fish from the Republican River Basin: 1997-1999

    USGS Publications Warehouse

    May, T.W.; Walther, M.J.; Petty, J.D.; Fairchild, J.F.; Lucero, J.; Delvaux, M.; Manring, J.; Armbruster, M.; Hartman, D.

    2001-01-01

    The Republican River Basin of Colorado, Nebraska, and Kansas lies in a valley which contains Pierre Shale as part of its geological substrata. Selenium is an indigenous constituent in the shale and is readily leached into surrounding groundwater. The Basin is heavily irrigated through the pumping of groundwater, some of which is selenium-contaminated, onto fields in agricultural production. Water, sediment, benthic invertebrates, and/or fish were collected from 46 sites in the Basin and were analyzed for selenium to determine the potential for food-chain bioaccumulation, dietary toxicity, and reproductive effects of selenium in biota. Resulting selenium concentrations were compared to published guidelines or biological effects thresholds. Water from 38% of the sites (n = 18) contained selenium concentrations exceeding 5 ??g L-1, which is reported to be a high hazard for selenium accumulation into the planktonic food chain. An additional 12 sites (26% of the sites) contained selenium in water between 3-5 ??g L-1, constituting a moderate hazard. Selenium concentrations in sediment indicated little to no hazard for selenium accumulation from sediments into the benthic food chain. Ninety-five percent of benthic invertebrates collected exhibited selenium concentrations exceeding 3 ??g g-1, a level reported as potentially lethal to fish and birds that consume them. Seventy-five percent of fish collected in 1997, 90% in 1998, and 64% in 1999 exceeded 4 ??g g-1 selenium, indicating a high potential for toxicity and reproductive effects. However, examination of weight profiles of various species of collected individual fish suggested successful recruitment in spite of selenium concentrations that exceeded published biological effects thresholds for health and reproductive success. This finding suggested that universal application of published guidelines for selenium may be inappropriate or at least may need refinement for systems similar to the Republican River Basin

  8. The influence of particle size on radionuclide activity concentrations in Tejo River sediments.

    PubMed

    Madruga, M J; Silva, L; Gomes, A R; Libânio, A; Reis, M

    2014-06-01

    Sediment samples from Tejo River were analyzed for (228)Ra, (226)Ra, (137)Cs and (40)K by HPGe gamma spectrometry. The activity concentration data were statistically analyzed. The activity concentrations values were in the range of about two orders of magnitude for each radionuclide. The influence of the particle size on the radionuclide concentrations was observed. The different environmental origins of the radionuclides (228)Ra, (226)Ra, (137)Cs and (40)K, in the sediments were demonstrated through correlation analysis. Cluster analysis showed a close relationship between (228)Ra and (226)Ra and a different behavior for (40)K. The data obtained in this study provides useful information on the background radioactivity of the studied area and can be further used for radiological mapping of the Tejo River. PMID:24561724

  9. Interannual heavy element and nutrient concentration trends in the top sediments of Venice Lagoon (Italy).

    PubMed

    Masiol, Mauro; Facca, Chiara; Visin, Flavia; Sfriso, Adriano; Pavoni, Bruno

    2014-12-15

    The elemental composition of surficial sediments of Venice Lagoon (Italy) in 1987, 1993, 1998 and 2003 were investigated. Zn and Cr concentrations resulted in higher than background levels, but only Cd and Hg were higher than legal quality standards (Italian Decree 2010/260 and Water Framework Directive 2000/60/EC). Contaminants with similar spatial distribution are sorted into three groups by means of correlation analysis: (i) As, Co, Cd, Cu, Fe, Pb, Zn; (ii) Ni, Cr; (iii) Hg. Interannual concentrations are compared by applying a factor analysis to the matrix of differences between subsequent samplings. A general decrease of heavy metal levels is observed from 1987 to 1993, whereas particularly high concentrations of Ni and Cr are recorded in 1998 as a consequence of intense clam fishing, subsequently mitigated by better prevention of illegal harvesting. Due to the major role played by anthropogenic sediment resuspension, bathymetric variations are also considered. PMID:25455371

  10. Partition of organochlorine concentrations among suspended solids, sediments and brown mussel Perna perna, in tropical bays.

    PubMed

    Galvao, Petrus; Henkelmann, Bernhard; Longo, Renan; Dorneles, Paulo Renato; Torres, João Paulo Machado; Malm, Olaf; Schramm, Karl-Werner

    2014-11-01

    For evaluating the brown mussel Perna perna as a sentinel organism regarding environmental concentrations of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), the present study reports original data on the relationship between the concentrations of these chemicals in bottom surface sediments, suspended solids (SS) and concentrations bioaccumulated by this bivalve. Three P. perna cultivation areas, located at three bays in southeastern Brazil were used in this study. The three estuaries are under different degrees of environmental impact. Variations in the OCP and PCB concentrations bioaccumulated by the bivalves tended to be similar to those observed in the sediment, but differed from those found in SS. This latter difference might suggest that the SS trapping apparatuses should have been left in place for approximately 60 days (not only 15 days). This longer period would allow the integration of the environmental variability of the OCP and PCB burden adsorbed to this compartment. Authors encourage future studies to evaluate P. perna exposure to OCPs and PCBs through the evaluation of sediment concentrations. PMID:25113178

  11. Factors affecting metal concentrations in the upper sediment layer of intertidal reedbeds along the river Scheldt.

    PubMed

    Du Laing, Gijs; Vandecasteele, Bart; De Grauwe, Pieter; Moors, Wouter; Lesage, Els; Meers, Erik; Tack, Filip M G; Verloo, Marc G

    2007-05-01

    Factors that play a role in determining metal accumulation in sediments of 26 intertidal marshes which are mainly vegetated by reed plants (Phragmites australis) were assessed along the Scheldt estuary (Belgium and The Netherlands). In the upper 20 cm sediment layer, several physico-chemical properties (clay, silt and sand content, organic matter, carbonate and chloride content, pH and conductivity) and aqua regia extractable metals (Cd, Cr, Cu, Ni, Pb, Zn) were determined. The sediments were significantly contaminated with trace metals. The Cd concentrations often exceeded the Flemish soil remediation thresholds for nature areas, whereas Cr, Cu and Zn levels indicated moderate contamination. Pb concentrations occasionally were high, whereas Ni concentrations leaned towards background values. Organic matter was the single most important predictor variable for total metal contents in regression models, except for Cr. Additional significant predictor variables were clay or chloride content, depending on the metal. Observed metal concentrations at sites within a range of a few km from specific point-sources of metals (e.g. shipyards, industrial areas with metallurgic activities, affluents, major motorways) were somewhat higher than predicted by the models, whereas they were lower than predicted at sites which are regularly subjected to flooding by water of high salinity. The ratio between observed and predicted concentrations seems to be a valuable tool for the identification of areas which are specifically impacted by point sources. PMID:17492090

  12. Model-based interpretation of sediment concentration and vertical flux measurements in a shallow estuarine environment

    USGS Publications Warehouse

    Brand, Andreas; Lacy, Jessica R.; Gladding, Steve; Holleman, Rusty; Stacey, Mark

    2015-01-01

    A one-dimensional numerical model describing tidally varying vertical mixing and settling was used to interpret sediment concentrations and vertical fluxes observed in the shoals of South San Francisco Bay by two acoustic Doppler velocimeters (ADVs) at elevations of 0.36 m and 0.72 m above bed. Measured sediment concentrations changed by up to 100 g m−3 over the semidiurnal tidal cycle. These dynamics were dominated by local resuspension and settling. Multiple particle class models suggested the existence of a class with fast settling velocities (ws of 9.0 × 10−4 m s−1 in spring and 5.8 × 10−4 m s−1 in fall) and a slowly settling particle fraction (ws of <1 × 10−7 m s−1 in spring and 1.4 × 10−5 m s−1 in fall). Modeled concentrations of slowly settling particles at 0.36 m were as high as 20 g m−3 during fall and varied with the spring-neap cycle while fine sediment concentrations in spring were constant around 5 g m−3. Analysis of in situ water column floc size distributions suggested that floc properties in the lower part of the water column were most likely governed by particle-size distribution on the bed and not by coagulation, validating our multiple particle size approach. A comparison of different sediment bed models with respect to model performance, sensitivity, and identifiability suggested that the use of a sediment erosion model linear in bottom shear stress τb (E = M (τb − τc)) was the most appropriate choice to describe the field observations when the critical shear stress τc and the proportionality factor M were kept constant.

  13. Effects of sediment characteristics on the toxicity of chromium(III) and chromium(VI) to the amphipod, Hyalella azteca

    USGS Publications Warehouse

    Besser, J.M.; Brumbaugh, W.G.; Kemble, N.E.; May, T.W.; Ingersoll, C.G.

    2004-01-01

    We evaluated the influence of sediment characteristics, acid-volatile sulfide (AVS) and organic matter (OM), on the toxicity of chromium (Cr) in freshwater sediments. We conducted chronic (28-42-d) toxicity tests with the amphipod Hyalella azteca exposed to Cr(VI) and Cr(III) in water and in spiked sediments. Waterborne Cr(VI) caused reduced survival of amphipods with a median lethal concentration (LC50) of 40 ??g/L. Cr(VI) spiked into test sediments with differing levels of AVS resulted in graded decreases in AVS and sediment OM. Only Cr(VI)-spiked sediments with low AVS concentrations (<1 ??mol/g) caused significant amphipod mortality. Waterborne Cr(III) concentrations near solubility limits caused decreased survival of amphipods at pH 7 and pH 8 but not at pH 6. Sediments spiked with high levels of Cr(III) did not affect amphipod survival but had minor effects on growth and inconsistent effects on reproduction. Pore waters of some Cr(III)-spiked sediments contained measurable concentrations of Cr(VI), but observed toxic effects did not correspond closely to Cr concentrations in sediment or pore waters. Our results indicate that risks of Cr toxicity are low in freshwater sediments containing substantial concentrations of AVS.

  14. 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.

  15. Heavy metal concentration in mangrove surface sediments from the north-west coast of South America.

    PubMed

    Fernández-Cadena, J C; Andrade, S; Silva-Coello, C L; De la Iglesia, R

    2014-05-15

    Mangrove ecosystems are coastal estuarine systems confined to the tropical and subtropical regions. The Estero Salado mangrove located in Guayaquil, Ecuador, has suffered constant disturbances during the past 20 years, due to industrial wastewater release. However, there are no published data for heavy metals present in its sediments and the relationship with anthropogenic disturbance. In the present study, metal concentrations were evaluated in surface sediment samples of the mangrove, showing that B, Cd, Cu, Pb, Se, V, and Zn levels exceeded those declared in international environmental quality standards. Moreover, several metals (Pb, Sn, Cd, Ag, Mo, Zn and Ni) could be linked to the industrial wastewater present in the studied area. In addition, heavy metal levels detected in this mangrove are higher than previous reports on mangrove sediments worldwide, indicating that this mangrove ecosystem is one of the most disrupted on earth. PMID:24685449

  16. Effects of copper on invertebrate-sediment interactions.

    PubMed

    Hunting, E R; Mulder, C; Kraak, M H S; Breure, A M; Admiraal, W

    2013-09-01

    Toxicants potentially decouple links between biodiversity and ecosystem processes. This study aimed to evaluate how toxicants affect invertebrate bioturbation and decomposition. Effects of copper on functionally distinct macrofaunal species (Asellus aquaticus and Tubifex spp.), decomposition (release of dissolved organic carbon, DOC) and Average Metabolic Response (AMR) and Community Metabolic Diversity (CMD) of bacteria were determined in 5-day microcosm experiments. Bioturbation was assessed as sediment redox potential (Eh) profiles. Concentration-response curves of the functional parameters DOC, and the faunal mediated AMR and CMD in the presence of Tubifex spp. depended on Tubifex spp. survival, i.e. similar EC50 values for both endpoints. In contrast, functional parameters in the presence of A. aquaticus were more sensitive than survival. Sediment Eh-profiles showed that reduced decomposition was caused by reduced sediment reworking by A. aquaticus at sub-lethal copper concentrations. These observations hint at a decoupling of invertebrate community structure and ecosystem functioning upon stress. PMID:23747821

  17. Discrimination of sediment provenance in the Yellow Sea: Secondary grain-size effect and REE proxy

    NASA Astrophysics Data System (ADS)

    Jung, Hoi-Soo; Lim, Dhongil; Jeong, Do-Hyun; Xu, Zhaokai; Li, Tiegang

    2016-06-01

    This study analyzed grain size and elemental concentrations (Al, Mg, Fe, and rare earth elements (REEs)) in 91 surface sediments to elucidate sediment provenance in the Yellow Sea. Elemental concentrations were normalized by Al concentration (Celement/CAl) to minimize the sediment grain-size effect (GSE). However, noticeable linear relationships between Al concentration (or mean grain size) and the ratio (e.g., Mg/Al or Fe/Al) appeared unexpectedly in pair diagrams. The spatial distribution patterns of Fe/Al and Mg/Al ratios were also similar to the pattern of mean grain size. This implies that the GSE was not removed completely, even after the normalization process. Thus, great care must be taken when applying the ratios of Celement/CAl as a proxy of sediment provenance. To improve provenance discrimination of the sediments in the Yellow Sea, the difference between the REE distribution patterns of Chinese and Korean river sediments, expressed as δ (δ = REE∗(La) - REE∗(Lu)), was calculated, and the spatial distribution patterns of the δ values were mapped. The δ values gradually increased from the western to the eastern part of the Yellow Sea, except for low δ values in the southeastern part of the Yellow Sea. This result indicates that the majority of Chinese and Korean river sediments are accumulating near to their respective coasts, except for a deposit along the southwestern coast of Korea in which a considerable amount of sediment from Chinese rivers has been accumulating.

  18. PCB concentration in fish in a river system after remediation of contaminated sediment

    SciTech Connect

    Bremle, G.; Larsson, P.

    1998-11-15

    An 1991 investigation of PCB concentrations in water and fish along a river was repeated in 1996 after the completion of a remediation of PCB-containing sediment in a lake within the river system. The PCB concentrations in the lake water decreased significantly, and the concentrations in fish was halved (significantly lower) after remediation. PCB still remaining in littoral sediment was probably the cause for a recorded gradient of PCB concentrations in fish from the lake and downstream. The PCB concentrations in water and fish was lower in 1996 compared to 1991 in all locations studied. The decreased levels of PCB in fish between the years for the two upstream locations, probably results from a decline in background PCB exposure. Monitoring data from 30 years back, recorded in a south Swedish lake, has shown a 5% decline per year in the PCB concentration in pike. The data on PCB concentration in fish from the two upstream locations were recalculated on the basis of this yearly decline and resulted in concentrations close to those measured in 1996. The results indicated, that changes in background exposure must be taken into account when evaluating the success of remedial actions measures carried out over several years.

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

    NASA Astrophysics Data System (ADS)

    Ikeuchi, Yoshihiro

    2003-09-01

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

  20. A comparison of load estimates using total suspended solids and suspended-sediment concentration data

    USGS Publications Warehouse

    Glysson, G.D.; Gray, J.R.; Schwarz, G.E.

    2001-01-01

    This paper presents the results to-date from a continuing investigation into the differences between total suspended solids (TSS) and suspended-sediment concentration (SSC) data and the ramifications of using each type of data to estimate sediment loads. It compares estimates of annual suspended-sediment loads that were made using regression equations developed from paired TSS and SSC data, to annual loads computed by the U.S. Geological Survey (USGS) using traditional techniques and SSC data. Load estimates were compared for 10 stations where sufficient TSS and SSC paired data were available to develop sediment-transport curves for the same time period that daily suspended-sediment records were available. Results of these analyses indicate that as the time frame over which the estimates were made increases, the overall errors associated with the estimates decreases with respect to loads computed using traditional USGS techniques. Using SSC data to compute loads tends to produce estimates closer to those computed by traditional techniques than those computed from TSS data. Loads computed from TSS data tend to be negatively biased with respect to those computed by traditional USGS techniques.

  1. Predicting the toxicity of sediment-associated trace metals with simultaneously extracted trace metal: Acid-volatile sulfide concentrations and dry weight-normalized concentrations: A critical comparison

    USGS Publications Warehouse

    Long, E.R.; MacDonald, D.D.; Cubbage, J.C.; Ingersoll, C.G.

    1998-01-01

    The relative abilities of sediment concentrations of simultaneously extracted trace metal: acid-volatile sulfide (SEM:AVS) and dry weight- normalized trace metals to correctly predict both toxicity and nontoxicity were compared by analysis of 77 field-collected samples. Relative to the SEM:AVS concentrations, sediment guidelines based upon dry weight-normalized concentrations were equally or slightly more accurate in predicting both nontoxic and toxic results in laboratory tests.

  2. Arsenic concentrations in Baltic Sea sediments close to chemical munitions dumpsites

    NASA Astrophysics Data System (ADS)

    Bełdowski, Jacek; Szubska, Marta; Emelyanov, Emelyan; Garnaga, Galina; Drzewińska, Anna; Bełdowska, Magdalena; Vanninen, Paula; Östin, Anders; Fabisiak, Jacek

    2016-06-01

    In addition to natural sources and land-originated pollution, the Baltic Sea has another anthropogenic source of arsenic in bottom sediments-arsenic-based Chemical Warfare Agents (CWA). To examine the potential usage of arsenic contents results for monitoring the leakage from chemical weapons, sediment samples were collected from officially reported and potential chemical weapon dumpsites located in the Baltic Sea, and total and inorganic arsenic concentrations were analyzed. Results showed an elevated arsenic content in dumpsite areas compared to reference areas. Correlations of arsenic with other metals and organic matter were studied to elucidate any unusual behavior of arsenic in the dumpsites. In the area of the Bornholm Deep, such behavior was observed for inorganic arsenic. It appears that in close vicinity of dumped munitions, the inorganic arsenic concentration of sediments is not correlated with either organic matter content or authigenic minerals formation, as is commonly observed elsewhere. Investigations on CWA concentrations, performed within the CHEMSEA (Chemical Munition Search and Assesment) project, allowed us to compare the results of arsenic concentrations with the occurrence of arsenic-containing CWA.

  3. Application of PAH concentration profiles in lake sediments as indicators for smelting activity.

    PubMed

    Warner, Wiebke; Ruppert, Hans; Licha, Tobias

    2016-09-01

    The ability of lake sediment cores to store long-term anthropogenic pollution establishes them as natural archives. In this study, we focus on the influence of copper shale mining and smelting in the Mansfeld area of Germany, using the depth profiles of two sediment cores from Lake Süßer See. The sediment cores provide a detailed chronological deposition history of polycyclic aromatic hydrocarbons (PAHs) and heavy metals in the studied area. Theisen sludge, a fine-grained residue from copper shale smelting, reaches the lake via deflation by wind or through riverine input; it is assumed to be the main source of pollution. To achieve the comparability of absolute contaminant concentrations, we calculated the influx of contaminants based on the sedimentation rate. Compared to the natural background concentrations, PAHs are significantly more enriched than heavy metals. They are therefore more sensitive and selective for source apportionment. We suggest two diagnostic ratios of PAHs to distinguish between Theisen sludge and its leachate: the ratio fluoranthene to pyrene ~2 and the ratio of PAH with logKOW<5.7 to PAH with a logKOW>5.7 converging to an even lower value than 2.3 (the characteristic of Theisen sludge) to identify the particulate input in lake environments. PMID:27176930

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

    USGS Publications Warehouse

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

    2012-01-01

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

  5. Correlating organic carbon concentration and composition with mineralogy in deep-sea pelagic sediments

    NASA Astrophysics Data System (ADS)

    Johnson, D.; Estes, E. R.; Hansel, C. M.; Anderson, C. H.; Murray, R. W.; Dyar, M. D.; Nordlund, D.; Wankel, S. D.; Spivack, A. J.; Sauvage, J.; McKinley, C. C.; Homola, K.; Present, T. M.; D'Hondt, S.

    2015-12-01

    The majority of organic matter sinking in the ocean is remineralized to carbon dioxide before it reaches the sea floor. Of the organic carbon (OC) that does reach the sediment-water interface, only a small fraction is buried. Organisms residing in the sediment column utilize minerals such as metal oxides as electron donors to degrade a portion of this carbon. However, there is evidence that these metal oxides may also, by adsorbing OC, enhance its preservation and thereby act as a sink for OC on geological timescales. The goal of this research is to examine the potential for mineral-based protection of OC in suboxic and oxic pelagic sediments. Using Elemental Analysis - Isotope Ratio Mass Spectrometry, we characterize the concentration and isotopic composition of OC and nitrogen in sediments collected during the R/V Knorr expedition 223 to the western subtropical North Atlantic in November 2014. Organic carbon concentrations range from 0.05 to 0.25 mol OC/kg sediment while organic nitrogen (ON) varies from 0.01 to 0.026 mol ON/kg sediment. OC concentrations initially decrease with depth but stabilize ~10 meters below core top, suggesting that OC is protected against remineralization since electron acceptors are still present to fuel anaerobic respiration. At the suboxic site, the ratio of OC/ON decreases sharply in the top two meters of the core and then stabilizes at a OC/ON value of approximately 5, illustrating an enrichment in ON relative to Redfield ratios. Oxidized solid-phase manganese (Mn), presumably Mn(III,IV) oxides, decreases with depth indicating active redox cycling. Conversely, solid-phase Fe(III) content as a proportion of total Fe remains relatively constant with depth. X-ray diffraction and density separations to isolate specific mineral classes, such as metal oxides and clays, were also employed to better correlate mineralogy with trends in OC concentrations. The relatively stable OC concentrations at depth suggest that OC is protected against

  6. Phosphorus amendment reduces hematological effects of lead in mallards ingesting contaminated sediments

    USGS Publications Warehouse

    Hoffman, D.J.; Heinz, G.H.; Audet, D.J.

    2006-01-01

    Lead poisoning of waterfowl has been reported for decades in the Coeur d?Alene River Basin (CDARB) in Idaho as a result of the ingestion of lead-contaminated sediments. This study was conducted to determine whether the addition of phosphoric acid to sediments would reduce the bioavailability and toxicity of lead to mallards (Anas platyrhynchos) as related to adverse hematological effects and altered plasma chemistries. Mallards received diets containing 12% clean sediment (controls) or 12% sediment from three different CDARB sites containing 4520, 5390, or 6990 :g/g lead (dw) with or without phosphoric acid amendment. Blood lead concentrations were significantly higher in all CDARB treatment groups and ranged from geometric mean values of 5.0 ug/g for the first two sites to 6.2 ug/g for the third site. With amendments, all blood lead concentrations became 41% to 64% lower. Red blood cell ALAD activity was depressed by 90% or more with lead-contaminated sediment from all sites and did not differ with amended diets. Free erythrocyte protoporphyrin (FEP) concentrations were elevated by contaminated sediment from all sites. Amendment decreased the elevations in FEP by as much as 80%. Hematocrit values and hemoglobin concentrations were lower for all lead site sediments by as much as 30% for site 3. Plasma enzyme activities for ALT, CK, and LDH-L were elevated by as much as 2.2-fold, and plasma creatinine concentration was 1.7-fold higher for site 3 sediment. Amendments restored hematocrit, hemoglobin, and plasma enzyme activities so that they did not differ from controls. Although amendments of phosphorus substantially reduced the bioavailability of lead and alleviated many of the adverse hematological effects, lead concentrations in the blood of mallards fed the amended sediments were still above those believed to be harmful to waterfowl under the present conditions.

  7. Effects of organic amendments on the toxicity and bioavailability of cadmium and copper in spiked formulated sediments

    USGS Publications Warehouse

    Besser, J.M.; Brumbaugh, W.G.; May, T.W.; Ingersoll, C.G.

    2003-01-01

    We evaluated the partitioning and toxicity of cadmium (Cd) and copper (Cu) spiked into formulated sediments containing two types of organic matter (OM), i.e., cellulose and humus. Amendments of cellulose up to 12.5% total organic carbon (TOC) did not affect partitioning of Cd or Cu between sediment and pore water and did not significantly affect the toxicity of spiked sediments in acute toxicity tests with the amphipod Hyalella azteca. In contrast, amendments of natural humus shifted the partitioning of both Cd and Cu toward greater concentrations in sediment and lesser concentrations in pore water and significantly reduced toxic effects of both metals. Thresholds for toxicity, based on measured metal concentrations in whole sediment, were greater for both Cd and Cu in sediments amended with a low level of humus (2.9% TOC) than in sediments without added OM. Amendments with a high level of humus (8.9% TOC) eliminated toxicity at the highest spike concentrations of both metals (sediment concentrations of 12.4 ??g Cd/g and 493 ??g Cu/g). Concentrations of Cd in pore water associated with acute toxicity were similar between sediments with and without humus amendments, suggesting that toxicity of Cd was reduced primarily by sorption to sediment OM. However, toxic effects of Cu in humus treatments were associated with greater pore-water concentrations than in controls, suggesting that toxicity of Cu was reduced both by sorption and by complexation with soluble ligands. Both sorption and complexation by OM tend to make proposed sediment quality guidelines (SQGs) based on total metal concentrations more protective for high-OM sediments. Our results suggest that the predictive ability of SQGs could be improved by models of metal interactions with natural OM in sediment and pore water.

  8. Effects of teflubenzuron on sediment processing by members of the Capitella species-complex.

    PubMed

    Méndez, Nuria

    2006-01-01

    The cosmopolitan deposit-feeding polychaete Capitella is widely used as an indicator of organic pollution and plays an important role in waste recycling at aquaculture sites. Teflubenzuron is currently employed by salmon farms as an in-feed compound to control ectoparasite infestations. Its occurrence in sediments could pose a hazard to local sediment infauna. A bioassay to investigate the effects of exposing Capitella sp I and Capitella sp B to sediment spiked with environmentally relevant concentrations of teflubenzuron (8.4, 25 and 41.8 microg/g dry wt. sediment) is described. No mortality was recorded for Capitella sp I, but increasing teflubenzuron concentrations significantly reduced egestion rates. Capitella sp B exhibited mortality, although egestion was not affected. These results using Capitella spp. indicated that teflubenzuron could affect the rate of sediment processing by polychaetes close to fish farms treated with this compound. Further studies are recommended to assess the potential of contaminants in aquaculture wastes. PMID:16084001

  9. Hydrogen concentrations as an indicator of the predominant terminal electron-accepting reactions in aquatic sediments

    USGS Publications Warehouse

    Lovley, D.R.; Goodwin, S.

    1988-01-01

    Factors controlling the concentration of dissolved hydrogen gas in anaerobic sedimentary environments were investigated. Results, presented here or previously, demonstrated that, in sediments, only microorganisms catalyze the oxidation of H2 coupled to the reduction of nitrate, Mn(IV), Fe(III), sulfate, or carbon dioxide. Theoretical considerations suggested that, at steady-state conditions, H2 concentrations are primarily dependent upon the physiological characteristics of the microorganism(s) consuming the H2 and that organisms catalyzing H2 oxidation, with the reduction of a more electrochemically positive electron acceptor, can maintain lower H2 concentrations than organisms using electron acceptors which yield less energy from H2 oxidation. The H2 concentrations associated with the specified predominant terminal electron-accepting reactions in bottom sediments of a variety of surface water environments were: methanogenesis, 7-10 nM; sulfate reduction, 1-1.5 nM; Fe(III) reduction, 0.2 nM; Mn(IV) or nitrate reduction, less than 0.05 nM. Sediments with the same terminal electron acceptor for organic matter oxidation had comparable H2 concentrations, despite variations in the rate of organic matter decomposition, pH, and salinity. Thus, each terminal electron-accepting reaction had a unique range of steady-state H2 concentrations associated with it. Preliminary studies in a coastal plain aquifer indicated that H2 concentrations also vary in response to changes in the predominant terminal electron-accepting process in deep subsurface environments. These studies suggest that H2 measurements may aid in determining which terminal electron-accepting reactions are taking place in surface and subsurface sedimentary environments. ?? 1988.

  10. Laboratory application of laser grain-size analyzer in determining suspended sediment concentration

    NASA Astrophysics Data System (ADS)

    Liu, Xiao; Feng, Xiuli; Liu, Jie; Lin, Lin

    2014-06-01

    Suspended sediment concentration (SSC) is an important parameter in marine sedimentology. With the development of technology, many acoustic and optical devices, such as the Laser In-Situ Scattering and Transmissometry, have been designed to measure in situ SSC and grain size distribution. But due to fund or other restrictions, many experiments were only conducted in laboratory, using an indoor laser grain-size analyzer and gravimetric method to measure grain size distribution and concentration, respectively. In this study the laboratory experiment is simplified by omitting the tiring step of gravimetric method. The connections between SSC and other parameters (obscuration, D50 and sorting index) were investigated based on 124 surface sediment samples collected from different offshore areas. A new method is developed for determining SSC in laboratory using a laser grain-size analyzer.

  11. Areal Distribution and Concentration of Contaminants of Concern in Surficial Streambed and Lakebed Sediments, Lake St. Clair and Tributaries, Michigan, 1990-2003

    USGS Publications Warehouse

    Rachol, Cynthia M.; Button, Daniel T.

    2006-01-01

    As part of the Lake St. Clair Regional Monitoring Project, the U.S. Geological Survey evaluated data collected from surficial streambed and lakebed sediments in the Lake Erie-Lake St. Clair drainages. This study incorporates data collected from 1990 through 2003 and focuses primarily on the U.S. part of the Lake St. Clair Basin, including Lake St. Clair, the St. Clair River, and tributaries to Lake St. Clair. Comparable data from the Canadian part of the study area are included where available. The data are compiled into 4 chemical classes and consist of 21 compounds. The data are compared to effects-based sediment-quality guidelines, where the Threshold Effect Level and Lowest Effect Level represent concentrations below which adverse effects on biota are not expected and the Probable Effect Level and Severe Effect Level represent concentrations above which adverse effects on biota are expected to be frequent. Maps in the report show the spatial distribution of the sampling locations and illustrate the concentrations relative to the selected sediment-quality guidelines. These maps indicate that sediment samples from certain areas routinely had contaminant concentrations greater than the Threshold Effect Concentration or Lowest Effect Level. These locations are the upper reach of the St. Clair River, the main stem and mouth of the Clinton River, Big Beaver Creek, Red Run, and Paint Creek. Maps also indicated areas that routinely contained sediment contaminant concentrations that were greater than the Probable Effect Concentration or Severe Effect Level. These locations include the upper reach of the St. Clair River, the main stem and mouth of the Clinton River, Red Run, within direct tributaries along Lake St. Clair and in marinas within the lake, and within the Clinton River headwaters in Oakland County. Although most samples collected within Lake St. Clair were from sites adjacent to the mouths of its tributaries, samples analyzed for trace-element concentrations

  12. Methane Concentrations and Biogeochemistry in Lake Sediments from Stordalen Mire, Sub-Arctic Sweden

    NASA Astrophysics Data System (ADS)

    Halloran, M.; DeStasio, J.; Erickson, L.; Johnson, J. E.; Varner, R. K.; Setera, J.; Prado, M. F.; Wik, M.; Crill, P. M.

    2013-12-01

    Lake sediments are an important global carbon sink of both allochthonous and autochthonous inputs. However, lakes are also known to emit carbon in gaseous form, most often as methane (CH4) or carbon dioxide (CO2), which are potent greenhouse gases. As northern latitudes warm, it is increasingly important to understand these gases and the sediments that store them. In July of 2013 we took 48 cores at 16 sites throughout three lakes surrounding a mire underlain by degrading permafrost in sub-arctic Sweden. The goal was to characterize the sedimentology and geochemistry of the lake sediments to better understand the production, distribution, and flux of CO2 and CH4 from these lakes. Villasjön is a shallow lake less than 1.5 meters deep, Mellan Harrsjön has a maximum depth of 7 meters and is stream-fed, and Inre Harrsjön has a maximum depth of 5 meters and is connected to Mellan Harrsjön. Published radiocarbon dates suggest that all three lakes formed approximately 3400 years ago. At each sample site, we retrieved 2 to 4 cores from the lake bottom, approximately 40-80 cm in length. The cores were sub-sampled for measurements of bulk TOC, TC, TN, TS, and CaCO3 (by difference) using a CHNS Elemental Analyzer, and grain size using a laser particle size analyzer. Headspace CO2 and CH4 by gas chromatography and infrared gas analysis (IRGA) yielded production rates and CH4 sediment concentrations. Dissolved inorganic carbon (DIC) from porewater extractions were analyzed using IRGA and stable carbon isotopes of DIC were analyzed via a Quantum Cascade Laser. The recovered sediments in the cores from all three lakes were composed of three layers: an upper layer of organic rich sediment (30-40 cm thick), a middle transition layer of mixed organic and lithogenic materials (5-10 cm thick), and a deep layer of grey lithogenic clay with less organic carbon (of variable thickness). Preliminary results from the 12 Villasjön sites indicate that CH4 is present and produced from the

  13. Elastic-wave velocity in marine sediments with gas hydrates: Effective medium modeling

    USGS Publications Warehouse

    Helgerud, M.B.; Dvorkin, J.; Nur, A.; Sakai, A.; Collett, T.

    1999-01-01

    We offer a first-principle-based effective medium model for elastic-wave velocity in unconsolidated, high porosity, ocean bottom sediments containing gas hydrate. The dry sediment frame elastic constants depend on porosity, elastic moduli of the solid phase, and effective pressure. Elastic moduli of saturated sediment are calculated from those of the dry frame using Gassmann's equation. To model the effect of gas hydrate on sediment elastic moduli we use two separate assumptions: (a) hydrate modifies the pore fluid elastic properties without affecting the frame; (b) hydrate becomes a component of the solid phase, modifying the elasticity of the frame. The goal of the modeling is to predict the amount of hydrate in sediments from sonic or seismic velocity data. We apply the model to sonic and VSP data from ODP Hole 995 and obtain hydrate concentration estimates from assumption (b) consistent with estimates obtained from resistivity, chlorinity and evolved gas data. Copyright 1999 by the American Geophysical Union.

  14. Impact of urbanization on the concentrations and distribution of organic contaminants in boreal lake sediments.

    PubMed

    Honkonen, Olga; Rantalainen, Anna-Lea

    2013-02-01

    The main goal of this study was to evaluate the impacts of a middle-sized Finnish urban area on the quality of sediments in an adjacent boreal lake. We investigated the sources and distribution of organic pollutants (polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs)) in the sediments from urban stormwater traps and from Lake Vesijärvi. Grab surface sediment samples were taken from Lake Vesijärvi at various distances (25-2,000 m) from four major stormwater drainage outlets and at 15 urban stormwater traps in areas with different degrees of urbanization. These samples were analysed for 16 PAHs and 28 PCBs with gas chromatography-mass spectrometry. The concentrations of pollutants in the lake sediments were elevated in the vicinity of the urban shore (∑PAH 3-16, ∑PCB up to 0.02-0.3 mg/kg dw) and decreased as a function of distance (∑PAH 0.1-2.5, ∑PCB 0.01-0.3 mg/kg dw at a distance of more than 500 m from the shore), whereas contamination levels in suburban areas were notably lower (∑PAH 0.1-3, ∑PCB < LOQ-0.03 mg/kg dw; did not decline with distance). Possible sources and pathways of contamination were also investigated. The majority of stormwater trap sediments contained predominantly asphalt-derived PAHs due to pulverized pavement. PAHs in lake sediments were of pyrogenic origin, including the combustion of gasoline, diesel and coal. Suggested pathways of lake contamination are urban runoff discharge, boat traffic and atmospheric deposition. PMID:22527470

  15. ESTIMATION OF BIOTA SEDIMENT ACCUMULATION FACTOR (BSAF) FROM PAIRED OBSERVATIONS OF CHEMICAL CONCENTRATIONS IN BIOTA AND SEDIMENT (FINAL REPORT)

    EPA Science Inventory

    Biota Sediment Accumulation Factor (BSAF) is a parameter describing bioaccumulation of sediment-associated organic compounds or metals into tissues of ecological receptors. The report provides information on methodologies to estimate BSAF for nonionic organic chemicals.

  16. Effects of the Release of Soil Organic Matter on Phenanthrene Sorption by Sediments.

    PubMed

    Zhang, Xiaoyan; Wu, Yaoguo; Hu, Sihai; Li, Tao

    2016-04-01

    The release of soil organic matter (SOM) has been frequently studied, while its effects on sorption kinetics and on the capacity of phenanthrene (PHE) on sediments have seldom been studied. In this study, sodium chloride (NaCl, 0-0.1 mol/L) was introduced to adjust the release of SOM, and three sediments were prepared: a raw sediment (S1), an eluted sediment (S2), and an SOM-removed sediment (S3). The release of SOM , with dissolved organic matter (DOM) formed in solution, was confirmed in sediment 1. Sorption kinetics on sediment 1 showed atypical results as three stages: rapid sorption, pseudo sorption with partial desorption, and slow sorption. Also, a defined "sorption valley" occurred in the kinetic curve, which can be qualitatively determined by the characteristics of the release of SOM, including its amount, rate and sequence in each SOM fraction. Sorption capacity on sediments 1 and 2 was negatively correlated with aqueous DOM concentrations. By changing sediment characteristics and solution properties, the release of SOM significantly impacts polycyclic aromatic hydrocarbons (PAHs) sorption behaviors. These results help clarify the transport of PAHs in sediment-water systems. PMID:27131058

  17. Peat formation concentrates arsenic within sediment deposits of the Mekong Delta

    NASA Astrophysics Data System (ADS)

    Stuckey, Jason W.; Schaefer, Michael V.; Kocar, Benjamin D.; Dittmar, Jessica; Pacheco, Juan Lezama; Benner, Shawn G.; Fendorf, Scott

    2015-01-01

    Mekong River Delta sediment bears arsenic that has been released to groundwater under anaerobic conditions over the past several thousand years. The oxidation state, speciation, and distribution of arsenic and the associated iron bearing phases are crucial determinants of As reactivity in sediments. Peat from buried mangrove swamps in particular may be an important host, source, or sink of arsenic in the Mekong Delta. The total concentration, speciation, and reactivity of arsenic and iron were examined in sediments in a Mekong Delta wetland by X-ray fluorescence spectrometry (XRF), X-ray absorption spectroscopy (XAS), and selective chemical extractions. Total solid-phase arsenic concentrations in a peat layer at a depth of 6 m below ground increased 10-fold relative to the overlying sediment. Extended X-ray absorption fine structure (EXAFS) spectroscopy revealed that arsenic in the peat was predominantly in the form of arsenian pyrite. Arsenic speciation in the peat was examined further at the micron-scale using μXRF and μX-ray absorption near-edge structure (XANES) spectroscopy coupled with principal component analysis. The multiple energy μXRF mapping and μXANES routine was repeated for both iron and sulfur phase analyses. Our μXRF/μXANES analyses confirm arsenic association with pyrite - a less reactive host phase than iron (hydr)oxides under anaerobic conditions. The arsenian pyrite likely formed upon deposition/formation of the peat in a past estuarine environment (∼5.5 ka BP), a process that is not expected under current geochemical conditions. Presently, arsenian pyrite is neither a detectable source nor a sink for aqueous arsenic in our sediment profile, and under present geochemical conditions represents a stable host of As under the reducing aquifer conditions of the Mekong Delta. Furthermore, organic carbon within the peat is unable to fuel Fe(III) reduction, as noted by the persistence of goethite which can be reduced microbially with the

  18. Shipboard magnetic field "noise" reveals shallow heavy mineral sediment concentrations in Chesapeake Bay

    USGS Publications Warehouse

    Shah, Anjana K.; Vogt, Peter R.; Rosenbaum, Joseph G.; Newell, Wayne; Cronin, Thomas M.; Willard, Debra A.; Hagen, Rick A.; Brozena, John; Hofstra, Albert

    2012-01-01

    Shipboard magnetic field data collected over Chesapeake Bay exhibit low-amplitude, short-wavelength anomalies that most likely indicate shallow concentrations of heavy mineral sediments. Piston core layers and black sand beach samples exhibit enhanced magnetic susceptibilities and carry remanent magnetization, with mineralogical analyses indicating ilmenite and trace magnetite and/or maghemite and hematite. The anomalies are subtle and would be filtered as noise using traditional approaches, but can instead be highlighted using spectral methods, thus providing nearly continuous coverage along survey tracks. The distribution of the anomalies provides constraints on relevant sorting mechanisms. Comparisons to sonar data and previous grab samples show that two of three areas surveyed exhibit short-wavelength anomalies that are clustered over sand-covered areas, suggesting initial sorting through settling mechanisms. This is supported by a correlation between core magnetic susceptibility and grain size. Near the Choptank River, where sediment resuspension is wave-dominated, anomalies show a sharp decrease with seafloor depth that cannot be explained by signal attenuation alone. In Pocomoke Sound, where both tidal currents and wave-action impact sediment resuspension, anomalies show a more gradual decrease with depth. Near the mouth of the bay, where there is a higher influx of sediments from the continental shelf, short-wavelength anomalies are isolated and do not appear to represent heavy mineral sand concentrations. These combined observations suggest the importance of further sorting by erosional processes in certain parts of the bay. Additionally, comparisons of these data to cores sampling pre-Holocene sediments suggest that the sorting of heavy minerals in higher energy, shallow water environments provides a mechanism for correlations between core magnetic susceptibility and sea-level changes.

  19. Assessing Sediment-Related Effects of Dam Removals

    NASA Astrophysics Data System (ADS)

    Wallick, J. Rose; Randle, Timothy

    2009-04-01

    Subcommittee on Sedimentation: Sediment Management and Dam Removal Workshop; Portland, Oregon, 14-16 October 2008; For a host of reasons including dam safety, maintenance costs, and ecological concerns, more dams are currently being removed each year in the United States than are being constructed. Because many reservoirs have accumulated sediments within their pools, dam removal can potentially impose a variety of sediment-related risks, including downstream effects on habitat, water quality, infrastructure, and flood storage. Sediment-related risks are particularly heightened when the sediment stored behind a dam is contaminated. Currently no standard procedure exists for assessing sediment-related risks associated with dam removal. As a result, there are wide-ranging levels of analysis used to predict and monitor sediment impacts after a dam is removed. To develop a decision framework for assessing sediment-related effects from dam removals, the U.S. Federal Subcommittee on Sedimentation (SOS) held a workshop in October on the campus of Portland State University, in Oregon, hosted by the U.S. Geological Survey's (USGS) Oregon Water Science Center. At the meeting, attendees crafted a decision framework that will help standardize data collection and analysis methods necessary for understanding sediment-related effects associated with dam removals.

  20. Coupling Between the Changes in CO2 Concentration and Sediment Biogeochemistry in the Salinas De San Pedro Mudflat, California, USA

    NASA Astrophysics Data System (ADS)

    Rezaie Boroon, M.; Diaz, S.; Torres, V.; Lazzaretto, T.; Dehyn, D.

    2013-12-01

    We investigated the effects of elevated carbon dioxide [CO2] on biogeochemistry of marsh sediment including speciation of selected heavy metals in Salinas de San Pedro mudflat in California. The Salinas de San Pedro mudflat has higher carbon (C) content than the vast majority of fully-vegetated salt marshes even with the higher tidal action in the mudflat. Sources for CO2 were identified as atmospheric CO2 as well as due to local fault degassing process. We measured carbon dioxide [CO2], methane [CH4], total organic carbon, dissolved oxygen, salinity, and heavy metal concentration in various salt marsh locations. Overall, our results showed that CO2 concentration ranging from 418.7 to 436.9 [ppm], which are slightly different in various chambers but are in good agreement with some heavy metal concentrations values in mudflat at or around the same location. The selected metal concentration values (ppm) ranging from 0.003 - 0.011(As); 0.001-0.005 (Cd); 0.04-0.02 (Cr); 0.13-0.38 (Cu); 0.11-0.38 (Pb); 0.0009-0.020 (Se); and 0.188-0.321 (Zn). The low dissolved O2 [ppm] in the pore water sediment indicates suboxic environment. Additionally, CO2 [ppm] and loss on ignition (LOI) [%] correlated inversely; the higher CO2 content, the lower was the LOI; that is to say the excess CO2 may caused higher rates of decomposition and therefore it leads to lower soil organic matter (LOI) [%] on the mudflat surface. It appears that the elevated CO2 makes changes in salt marsh pore water chemistry for instance the free ionic metal (Cu2+, Pb2+, etc.) speciation is one of the most reactive form because simply assimilated by the non-decayed or alive organisms in sediment of salt marsh and/or in water. This means that CO2 not only is a sign of improvement in plant productivity, but also activates microbial decomposition through increases in dissolved organic carbon availability. CO2 also increases acidification processes such as anaerobic degradation of microorganism and oxidation of

  1. Visualizing the internal structure of subaqueous, high-concentration sediment-laden flows: implication of rheology to flow structure

    NASA Astrophysics Data System (ADS)

    Perillo, M. M.; Buttles, J.; Mohrig, D. C.; Kane, I.; Pontén, A.; Brown, D.; Minton, B. W.

    2013-12-01

    Subaqueous sediment-laden flows are thought to be the main mechanism transporting sediments to the deep sea. Understanding the processes governing these flows is crucial to building predictive models of flow behaviour, sediment transport and deposition and is applicable to a wide range of disciplines. Physical modelling using a wide range of experimental facilities and measurement techniques has significantly advanced our understanding of these sediment-laden flows and their ability to erode, transport and deposit sediments. However, for the case of high-sediment concentration flows, measuring flow and depositional properties is still a challenge. Here, we present results from an acoustic reflection technique that allows for direct and noninvasive visualization of the internal structure of high concentration, clay-rich, sand-laden flows with a range of initial yield strengths (0-26 Pa). As the acoustic signal travels through the sediment-laden flow, it encounters zones of varying acoustic impedance that are due to temporal and spatial changes in sediment concentration, grain size and sorting, and flow mixing. The reflected signal is processed and interpreted using seismic techniques developed in exploration geophysics. The ultrasonic reflection data captured two distinct flow stages, an active stage and a post-depositional creeping stage. The clay-rich sand-laden flows showed stratification expressed by three clear vertical zones: (a) an upper relatively dilute turbulent zone, (b) a zone with high sediment concentration and significantly reduced mixing and (c) an aggrading bed of static grains.

  2. 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. PMID:26205073

  3. Concentrations of chlorinated organic compounds in biota and bed sediment in streams of the San Joaquin Valley, California

    USGS Publications Warehouse

    Brown, L.R.

    1997-01-01

    Samples of resident biota and bed sediments were collected in 1992 from 18 sites on or near the floor of the San Joaquin Valley, California, for analysis of 33 organochlorine compounds. The sites were divided into five groups on the basis of physiographic region and land use. Ten compounds were detected in tissue, and 15 compounds were detected in bed sediment. The most frequently detected compound in both media was p,p'-DDE. Concentrations of ??DDT (sum of o,p'- and p, p' forms of DDD, DDE, and DDT) were statistically different among groups of sites for both tissue and sediment (Kruskal- Wallis, p < 0.05). Concentrations in both media were highest in streams draining the west side of the valley. Concentrations of ??DDT in tissue were significantly correlated with specific conductance, pH, and total alkalinity (p < 0.05), which are indicators of the proportion of irrigation return flows in stream discharge. Concentrations in sediment on a dry-weight basis were not correlated with these water-quality parameters, but total organic carbon (TOC) normalized concentrations were significantly correlated with specific conductance and pH (p < 0.05). Regressions of the concentration of ??DDT in tissue, as a function of ??DDT in bed sediment, were significant and explained up to 76% of the variance in the data. The concentration of ??DDT in sediment may be related to mechanisms of soil transport to surface water with bioavailability of compounds related to the concentration of TOC in sediment. The results of this study did not indicate any clear advantage to using either bed sediment or tissues in studies of organochlorine chemicals in the environment. Some guidelines for protection of fish and wildlife were exceeded. Concentrations of organochlorine chemicals in biota, and perhaps sediment, have declined from concentrations measured in the 1970s and 1980s, but remain high compared to other regions of the United States.

  4. Organic carbon concentration profiles in recent cave sediments: records of agricultural pollution or diagenesis?

    PubMed

    Bottrell, S H

    1996-01-01

    Recent (<7 years old) cave sediments in Speedwell Cavern, Derbyshire, show an approximately exponential decay of organic carbon with depth. This phenomenon was thought to be due to one of two causes: (i) changing agricultural practice within the catchment feeding the cave, especially the increased use of sewage sludge and animal slurry as fertilizer; (ii) a relatively constant organic carbon concentration over time in the input sediment, with subsequent carbon mineralization during diagenesis. Carbon isotope composition of the organic material and the evolution of H/C ratio with depth indicate that the latter hypothesis is correct and that the profiles result from microbial diagenesis, not increased organic carbon inputs. By comparison with sediment of known (7 years) age, temporal decay constants for organic matter can be derived; these lie between rates previously determined for organic matter decomposition in marine sediments and soils. The H/C ratio of organic matter can be modelled as a function of time and proceeds in a similar fashion to soil organic material. PMID:15091425

  5. The effects of Hurricane Hugo on suspended-sediment loads, Lago Loiza Basin, Puerto Rico

    USGS Publications Warehouse

    Gellis, A.

    1993-01-01

    In the two main tributaries that enter Lago Loiza, Rio Grande de Loiza and Rio Gurabo, 99 600 tonnes of suspended sediment was transported by 58.2??106 m3 of runoff in a 48 h period. The storm-average suspended-sediment concentration in the Rio Grande de Loiza for Hurricane Hugo was 2290 mgl-1, the second lowest for the 12 storms that have been monitored at this site. In Rio Gurabo the storm-average suspended-sediment concentration was 1420 mg l -1, the sixth lowest recorded out of 15 monitored storms. In Quebrada Salvatierra, a small tributary to Rio Grande de Loiza, suspended-sediment concentrations were as low as 33 mg l-1 during peak runoff of 20m3s-1. Normally the suspended-sediment concentrations at this discharge are 300 mg l-1. Hurricane force winds seem to be the most important factor contributing to the lower than expected suspended-sediment loads. High winds caused vegetation and debris to be dislodged and displaced. Debris accumulated on hillslopes and in small channels, blocked bridges and formed debris dams. These dams caused local backwater effects that reduced stream velocities and decreased suspended-sediment loads. -from Author

  6. Copula frequency analyses of peak discharge, hydrograph volume and suspended sediment concentration

    NASA Astrophysics Data System (ADS)

    Bezak, Nejc; Mikoš, Matjaž; Brilly, Mitja; Šraj, Mojca

    2014-05-01

    The aim of the study was to carry out frequency analyses of peak discharge, hydrograph volume and suspended sediment concentration series on one station from Slovenia and on five stations from USA with the use of 3-dimensional symmetric and asymmetric copula functions. Many water resources manager's deals with problem of hydropower reservoir filling and turbine abrasion and proper procedures are needed in order to estimate suspended sediment loads. Furthermore most of the suspended material is transported during few extreme events, which are usually in coincidence with annual maximum peak discharge values and consequently also with corresponding hydrograph volumes. Univariate frequency analyses are mostly performed in hydrology to obtain relationship between design variables and return period. However many hydrological processes are multidimensional and therefore copulas seem to be an interesting option for simultaneous modelling of peak discharges, hydrograph volumes and suspended sediment concentrations. Stations with watershed areas between 920 km2 and 24996 km2 were used in order to test the proposed procedure of trivariate frequency analyses of peak discharge, hydrograph volume and suspended sediment concentration using copula functions. First baseflow was separated in order to determine hydrograph volumes. Different parametric marginal distribution functions were tested and optimal distributions were selected based on RMSE, MAE model selection criteria, Kolmogorov-Smirnov test and graphical QQ plots. Univariate distribution functions parameters were estimated with the use of method of L-moments, parameters of copulas were estimated with maximum pseudo-likelihood method. Symmetric and asymmetric versions of Gumbel-Hougaard, Frank and Clayton copulas were compared. Statistical (Cramér-von Mises) and graphical tests for copulas were used in order to determine the most appropriate copula function and also primary and secondary return periods were calculated (OR

  7. Relationship between Sediment Chemistry, Equilibrium Phosphorus Concentrations, and Phosphorus Concentrations at Baseflow in Rivers of the New Zealand National River Water Quality Network.

    PubMed

    McDowell, R W

    2015-05-01

    Stream sediments can act as a source or a sink of dissolved (filtered) phosphorus (P) via abiotic and biotic processes. The cumulative action and magnitude of abiotic processes has been quantified by the equilibrium P concentration at zero net sorption or desorption (EPC). The EPC was determined in 76 large rivers of contrasting climate, topography, and geology across New Zealand. Measurements of EPC (0.004-0.065 mg L) indicated sediments were acting as a source of filtered reactive P (FRP) to the water column. The EPC was related to the proportion of intensive agriculture in the catchment, the concentration of readily available P in the sediment, sediment size, and catchment slope and elevation. Determination of EPC will yield a relative assessment of the sediment's ability to supply P to the water column especially at baseflow. Furthermore, the EPC may be less prone to short-term variation (e.g., diurnal patterns) compared with grab samples. This information will help target efforts to mitigate FRP concentrations in rivers by managing sediment inputs. Additional work is required to determine, for instance, how long an EPC measurement remains valid before new sediment is deposited or existing sediment is scoured. PMID:26024272

  8. Effects of hurricanes Katrina and Rita on the chemistry of bottom sediments in Lake Pontchartrain, Louisiana, USA

    USGS Publications Warehouse

    Van Metre, P.C.; Horowitz, A.J.; Mahler, B.J.; Foreman, W.T.; Fuller, C.C.; Burkhardt, M.R.; Elrick, K.A.; Furlong, E.T.; Skrobialowski, S.C.; Smith, J.J.; Wilson, J.T.; Zaugg, S.D.

    2006-01-01

    The effects of Hurricanes Katrina and Rita and the subsequent unwatering of New Orleans, Louisiana, on the sediment chemistry of Lake Pontchartrain were evaluated by chemical analysis of samples of street mud and suspended and bottom sediments. The highest concentrations of urban-related elements and compounds (e.g., Pb, Zn, polycyclic aromatic hydrocarbons, and chlordane) in bottom sediments exceeded median concentrations in U.S. urban lakes and sediment-quality guidelines. The extent of the elevated concentrations was limited, however, to within a few hundred meters of the mouth of the 17th Street Canal, similar to results of historical assessments. Chemical and radionuclide analysis of pre- and post-Hurricane Rita samples indicates that remobilization of near-shore sediment by lake currents and storms is an ongoing process. The effects of Hurricanes Katrina and Rita on the sediment chemistry of Lake Pontchartrain are limited spatially and are most likely transitory. ?? 2006 American Chemical Society.

  9. Trace element, semivolatile organic, and chlorinated organic compound concentrations in bed sediments of selected streams at Fort Gordon, Georgia, February-April 2010

    USGS Publications Warehouse

    Thomas, Lashun K.; Journey, Celeste A.; Stringfield, Whitney J.; Clark, Jimmy M.; Bradley, Paul M.; Wellborn, John B.; Ratliff, Hagan; Abrahamsen, Thomas A.

    2011-01-01

    sediment samples from most nonreference sites exceeded concentrations in samples from reference sites at Fort Gordon. Bed sediments from one of the nonreference sites sampled contained the highest concentrations of copper and lead with elevated levels of zinc and chromium relative to reference sites. The percentage change of major ions, trace elements, and total organic carbon that had been detected at sites previously sampled in May 1998 and current bed sediment sites ranged from -4 to 8 percent with an average percentage change of less than 1 percent. Concentrations of major ions and trace elements in bed sediments exceeded probable effect levels for aquatic life (based on the amphipod Hyalella azteca) established by the U.S. Environmental Protection Agency at 46 and 69 percent of the current and previously sampled locations, respectively. The greatest frequency of exceedances for major ions and trace elements in bed sediments was observed for lead. Concentrations of semivolatile organic compounds, organochlorine pesticides, and polychlorinated biphenyls were detected in bed sediment samples at 94 percent of the sites currently sampled. Detections of these organic compounds were reported with greater frequency in bed sediments at upstream sampling locations, when compared to downstream locations. The greatest number of detections of these compounds was reported for bed sediment samples collected from two creeks above a lake. The percentage change of semivolatile organic compounds detected at previously sampled and current bed sediment sites ranged from -68 to 100 percent with the greatest percentage increase reported for one of the creeks above the lake. Concentrations of semivolatile organic compounds and polychlorinated biphenyls in bed sediments exceeded aquatic life criteria established by the U.S. Environmental Protection Agency at three sites. Contaminant compounds exceeding aquatic life criteria included fluoranthene, phenanthrene, anthracene, benzo(a)anthracene

  10. Evolution of platinum concentration in soil and sediment from urban environment

    NASA Astrophysics Data System (ADS)

    Jean-Soro, L.

    2012-04-01

    Since the 1990s, platinum is widely used in automotive catalytic converters in Europe. However, only few environmental data about this element are available. The aim of this study was: - in a first part, to detected changes that may occur on the concentration and the distribution of platinum in urban and peri-urban environment over the 20-years last period, to evaluate the long term urban soil retention capacity; - in a second part, to investigated the sorption capacity of soil components. The study was conducted on samples from a peri-urban area, particularly on soil and sediment. The soil was sampled along an highway (Nantes ring road, western France) and the sediment was sampled in a detention pond receiving highway runoff waters. The first site is a motorway which was opened in 1993 with an average daily traffic of 24,000 vehicles. To date, the average daily traffic is about 50,000 vehicles. The second site is a detention pond which receives highway runoff from the Cheviré bridge. This road started to operate in 1991 and the bridge supported an average daily traffic of about 50,000 vehicles. Now, the traffic is about 98,000 vehicles/day. A physico-chemical analysis of the samples was carried out to identify the nature of pollutants and to determine their concentrations. The first result concern the evolution of pollutant concentrations in the environment, taking into account the changes such as the use decrease of Pb in gasoline (until its ban in 2000) and the widespread use of automotive catalytic converters. The results obtained show an increase of platinum concentrations with time in the detention pond sediments. Platinum concentrations are ranged from 47 to 144 µg.kg-1. For roadside soil the higher concentration (106 µg.kg-1) was found in the road dust collected close to the road pavement. This accumulated dust can be remobilised by wind, traffic and runoff. Then, there is a decrease of concentration with the distance from the road. The second part of

  11. Effects of algae growth on cadmium remobilization and ecological risk in sediments of Taihu Lake.

    PubMed

    Ni, Lixiao; Li, Dandan; Su, Lili; Xu, Jiajun; Li, Shiyin; Ye, Xiang; Geng, Hong; Wang, Peifang; Li, Yi; Li, Yiping; Acharya, Kumud

    2016-05-01

    Indoor simulation experiment with 2.76 L microcosms using sediment from Taihu Lake were conducted to investigate the relationship between algae bloom and heavy metals release into a lake aquatic environment. The results showed that Microcystic aeruginosa (M. aeruginosa) growth can enhance cadmium (Cd) mobilization from sediments to overlying water due to increasing pH and DO content of overlying water and changing the redox condition of surface sediment (0-2 cm) from weak oxidation to weak reduction. The dissolved Cd concentration in overlying water can be decreased during algal growth process. The remobilization of Cd from sediment can effectively reduce the ecological risk of total Cd in sediments. The results of this study showed that both Igeo and Er(i) can be used to effectively evaluate the ecological risk of heavy metal Cd in different fractions. PMID:26923240

  12. Complex patterns in fish - sediment mercury concentrations in a contaminated estuary: The influence of selenium co-contamination?

    NASA Astrophysics Data System (ADS)

    Jones, H. J.; Swadling, K. M.; Butler, E. C. V.; Macleod, C. K.

    2014-01-01

    Environmental mercury (Hg) loads do not always correspond to Hg concentrations in resident fish and selenium (Se) presence has been reported to play a pivotal role in mitigating Hg bioaccumulation. Total mercury (THg), methylmercury (MeHg) and Se concentrations were measured in sediments and a benthic fish species (Platycephalus bassensis) from a contaminated estuary (Derwent Estuary, Tasmania). Elevated sediment concentrations of Se did not result in increased Se concentrations in fish, but low concentrations of Se were associated with increased MeHg bioavailability (% MeHg) from sediments to fish. Where MeHg (≈99% of total Hg) concentration in fish was high Se uptake also increased, indicating that maintaining positive Se:Hg ratios may reduce the toxicity of MeHg. MeHg was detectable in sediments throughout the estuary, and a molar excess of THg over Se suggested that there was insufficient Se to prevent methylation from the sediments. Se:Hg ratios of less than 1.0 in sediments, coupled with high %MeHg fraction and high biotic sediment accumulation factors for MeHg (BSAFMeHg), indicated that the lower region of the Derwent Estuary could be a hotspot for Hg methylation, despite having significantly lower THg concentrations. In contrast, Hg bioavailability to fish from sediments close to the source may be reduced by both inorganic Hg species complexation and lower methylation rates. There was a strong association between THg and Se in estuarine sediments, suggesting that Se plays an important role in sediment Hg cycling and should be a key consideration in any future assessments of Hg methylation, bioavailability and bioaccumulation.

  13. The use of modeling and suspended sediment concentration measurements for quantifying net suspended sediment transport through a large tidally dominated inlet

    USGS Publications Warehouse

    Erikson, Li H.; Wright, Scott A.; Elias, Edwin; Hanes, Daniel M.; Schoellhamer, David H.; Largier, John

    2013-01-01

    Sediment exchange at large energetic inlets is often difficult to quantify due complex flows, massive amounts of water and sediment exchange, and environmental conditions limiting long-term data collection. In an effort to better quantify such exchange this study investigated the use of suspended sediment concentrations (SSC) measured at an offsite location as a surrogate for sediment exchange at the tidally dominated Golden Gate inlet in San Francisco, CA. A numerical model was calibrated and validated against water and suspended sediment flux measured during a spring–neap tide cycle across the Golden Gate. The model was then run for five months and net exchange was calculated on a tidal time-scale and compared to SSC measurements at the Alcatraz monitoring site located in Central San Francisco Bay ~ 5 km from the Golden Gate. Numerically modeled tide averaged flux across the Golden Gate compared well (r2 = 0.86, p-value

  14. Improved Method for the Quantification of Methane Concentrations in Unconsolidated Lake Sediments.

    PubMed

    Tyroller, Lina; Tomonaga, Yama; Brennwald, Matthias S; Ndayisaba, Cyprien; Naeher, Sebastian; Schubert, Carsten; North, Ryan P; Kipfer, Rolf

    2016-07-01

    There is conclusive evidence that the methods most commonly used to sample methane (CH4) dissolved in the pore water of lake sediments produce results that are likely to be affected by gas loss or gas exchange with the atmosphere. To determine the in situ amount of CH4 per unit mass of pore water in sediments, we developed and validated a new method that combines techniques developed for noble-gas analysis in pore waters with a standard headspace technique to quantify the CH4 present in the pore space in dissolved and gaseous form. The method was tested at two sites: Lake Lungern, where CH4 concentrations were close to saturation; and Lake Rotsee, where CH4 concentrations are known to exceed saturation and where CH4 bubble formation and gas ebullition are commonly observed. We demonstrate that the new method, in contrast to the available methods, more reliably captures the total amount of CH4 per unit mass of pore water consisting of both dissolved and free CH4 (i.e., gas bubbles) in the pore space of the sediment. PMID:27244276

  15. A Stochastic Framework For Sediment Concentration Estimation By Accounting Random Arrival Processes Of Incoming Particles Into Receiving Waters

    NASA Astrophysics Data System (ADS)

    Tsai, C.; Hung, R. J.

    2015-12-01

    This study attempts to apply queueing theory to develop a stochastic framework that could account for the random-sized batch arrivals of incoming sediment particles into receiving waters. Sediment particles, control volume, mechanics of sediment transport (such as mechanics of suspension, deposition and resuspension) are treated as the customers, service facility and the server respectively in queueing theory. In the framework, the stochastic diffusion particle tracking model (SD-PTM) and resuspension of particles are included to simulate the random transport trajectories of suspended particles. The most distinguished characteristic of queueing theory is that customers come to the service facility in a random manner. In analogy to sediment transport, this characteristic is adopted to model the random-sized batch arrival process of sediment particles including the random occurrences and random magnitude of incoming sediment particles. The random occurrences of arrivals are simulated by Poisson process while the number of sediment particles in each arrival can be simulated by a binominal distribution. Simulations of random arrivals and random magnitude are proposed individually to compare with the random-sized batch arrival simulations. Simulation results are a probabilistic description for discrete sediment transport through ensemble statistics (i.e. ensemble means and ensemble variances) of sediment concentrations and transport rates. Results reveal the different mechanisms of incoming particles will result in differences in the ensemble variances of concentrations and transport rates under the same mean incoming rate of sediment particles.

  16. Method for relating suspended-chemical concentrations to suspended-sediment particle-size classes in storm-water runoff

    USGS Publications Warehouse

    Rinella, Joseph F.; McKenzie, Stuart W.

    1982-01-01

    A method has been developed to relate suspended-chemical concentrations (associated with suspended sediments) in storm-water runoff to suspended-sediment particle-size classes. These classes are based on settling velocities in quiescent native water. This method requires processing 20 liters of water having a suspended-sediment concentration greater than 500 milligrams per liter. However, samples with suspended-sediment concentrations as low as 250 milligrams per liter may be analyzed, if sample volumes are increased to 50 liters. The time required for one person to separate suspended sediments into particle-size classes ranges from 6 to 14 hours. This report outlines procedures for processing metal, nutrient, and organic samples. (USGS)

  17. Method for relating suspended-chemical concentrations to suspended-sediment particle-size classes in storm-water runoff

    USGS Publications Warehouse

    Rinella, Joseph F.; McKenzie, Stuart W.

    1982-01-01

    A method has been developed to relate suspended-chemical concentrations (associated with suspended sediments) in storm-water runoff to suspended-sediment particle-size classes. These classes are based on settling velocities in quiescent native water. This method requires processing 20 liters of water having a suspended-sediment concentration greater than 500 milligrams per liter. However, samples with suspended-sediment concentrations as low as 250 milligrams per liter may be analyzed, if sample volumes are increased to 50 liters. The time required for one person to separate suspended sediments into particle-size classes ranges from 6 to 14 hours. This report outlines procedures for processing metal, nutrient, and organic samples.

  18. Determination of respirable mass concentration using a high volume air sampler and a sedimentation method for fractionation

    SciTech Connect

    Johnson, J.

    1995-12-31

    A preliminary study of a new method for determining respirable mass concentration is described. This method uses a high volume air sampler and subsequent fractionation of the collected mass using a particle sedimentation technique. Side-by-side comparisons of this method with cyclones were made in the field and in the laboratory. There was good agreement among the samplers in the laboratory, but poor agreement in the field. The effect of wind on the samplers` capture efficiencies is the primary hypothesized source of error among the field results. The field test took place at the construction site of a hazardous waste landfill located on the Hanford Reservation.

  19. Towards science-based sediment quality standards-Effects of field-collected sediments in rainbow trout (Oncorhynchus mykiss).

    PubMed

    Brinkmann, Markus; Eichbaum, Kathrin; Reininghaus, Mathias; Koglin, Sven; Kammann, Ulrike; Baumann, Lisa; Segner, Helmut; Zennegg, Markus; Buchinger, Sebastian; Reifferscheid, Georg; Hollert, Henner

    2015-09-01

    Sediments can act as long-term sinks for environmental pollutants. Within the past decades, dioxin-like compounds (DLCs) such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) have attracted significant attention in the scientific community. To investigate the time- and concentration-dependent uptake of DLCs and PAHs in rainbow trout (Oncorhynchus mykiss) and their associated toxicological effects, we conducted exposure experiments using suspensions of three field-collected sediments from the rivers Rhine and Elbe, which were chosen to represent different contamination levels. Five serial dilutions of contaminated sediments were tested; these originated from the Prossen and Zollelbe sampling sites (both in the river Elbe, Germany) and from Ehrenbreitstein (Rhine, Germany), with lower levels of contamination. Fish were exposed to suspensions of these dilutions under semi-static conditions for 90 days. Analysis of muscle tissue by high resolution gas chromatography and mass spectrometry and of bile liquid by high-performance liquid chromatography showed that particle-bound PCDD/Fs, PCBs and PAHs were readily bioavailable from re-suspended sediments. Uptake of these contaminants and the associated toxicological effects in fish were largely proportional to their sediment concentrations. The changes in the investigated biomarkers closely reflected the different sediment contamination levels: cytochrome P450 1A mRNA expression and 7-ethoxyresorufin-O-deethylase activity in fish livers responded immediately and with high sensitivity, while increased frequencies of micronuclei and other nuclear aberrations, as well as histopathological and gross pathological lesions, were strong indicators of the potential long-term effects of re-suspension events. Our study clearly demonstrates that sediment re-suspension can lead to accumulation of PCDD/Fs and PCBs in fish

  20. Methane gas hydrate effect on sediment acoustic and strength properties

    USGS Publications Warehouse

    Winters, W.J.; Waite, W.F.; Mason, D.H.; Gilbert, L.Y.; Pecher, I.A.

    2007-01-01

    To improve our understanding of the interaction of methane gas hydrate with host sediment, we studied: (1) the effects of gas hydrate and ice on acoustic velocity in different sediment types, (2) effect of different hydrate formation mechanisms on measured acoustic properties (3) dependence of shear strength on pore space contents, and (4) pore pressure effects during undrained shear. A wide range in acoustic p-wave velocities (Vp) were measured in coarse-grained sediment for different pore space occupants. Vp ranged from less than 1 km/s for gas-charged sediment to 1.77–1.94 km/s for water-saturated sediment, 2.91–4.00 km/s for sediment with varying degrees of hydrate saturation, and 3.88–4.33 km/s for frozen sediment. Vp measured in fine-grained sediment containing gas hydrate was substantially lower (1.97 km/s). Acoustic models based on measured Vp indicate that hydrate which formed in high gas flux environments can cement coarse-grained sediment, whereas hydrate formed from methane dissolved in the pore fluid may not. The presence of gas hydrate and other solid pore-filling material, such as ice, increased the sediment shear strength. The magnitude of that increase is related to the amount of hydrate in the pore space and cementation characteristics between the hydrate and sediment grains. We have found, that for consolidation stresses associated with the upper several hundred meters of sub-bottom depth, pore pressures decreased during shear in coarse-grained sediment containing gas hydrate, whereas pore pressure in fine-grained sediment typically increased during shear. The presence of free gas in pore spaces damped pore pressure response during shear and reduced the strengthening effect of gas hydrate in sands.

  1. Heavy metal concentrations in litteral sediments from the Beagle Channel, Tierra del Fuego, Argentina.

    PubMed

    Amin, O; Ferrer, L; Marcovecchio, J

    1996-07-01

    For the first time the concentration of trace metals (Fe, Pb, Cu, Zn, Cd and total Hg) of sediments from the coastal zone of the Beagle Channel (Tierra del Fuego, in Southern Argentina) were measured. Atomic absorption spectrophotometry was utilized in order to determine the metal contents. The level of metals as observed in the sediments was recognized as the natural background, even though the use of normalization of lead, copper, and zinc to iron allowed the identification of the main sources of metal pollution for this environment. In order to develop future environmental monitoring programmes for the area of Ushuaia city and the Beagle Channel, the present results need to be considered. PMID:24193396

  2. Trace metal concentrations and their transfer from sediment to leaves of four common aquatic macrophytes.

    PubMed

    Łojko, Renata; Polechońska, Ludmiła; Klink, Agnieszka; Kosiba, Piotr

    2015-10-01

    In the present study, the concentrations of trace and alkali metals in leaves of four common helophytes, Sparganium erectum, Glyceria maxima, Phalaris arundinacea, and Phragmites australis, as well as in corresponding water and bottom sediments were investigated to ascertain plant bioaccumulation ability. Results showed that Mn and Fe were the most abundant trace metals in all plant species, while Co and Pb contents were the lowest. Leaves of species studied differed significantly in respect of element concentrations. The highest concentrations of Mg, Na, Fe, Mn, Cu, Pb, and Ni were noted in S. erectum while the highest contents of Co, Ca, Zn, and Cr in Phalaris arundinacea. Phragmites australis contained the lowest amounts of most elements. Concentrations of Co, Cr, Fe, and Mn in all species studied and Ni in all except for Phragmites australis were higher than natural for hydrophytes. The leaves/sediment ratio was more than unity for all alkali metals as well as for Cu and Mn in Phragmites australis; Cr, Co, and Zn in Phalaris arundinacea; Cr and Mn in S. erectum; and Cr in G. maxima. High enrichment factors and high levels of toxic metals in the species studied indicated a special ability of these plants to absorb and store certain non-essential metals and, consequently, their potential for phytoremediation of contaminated aquatic ecosystems. PMID:26004561

  3. Response of coliform populations in streambed sediment and water column to changes in nutrient concentrations in water

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aims: The focus of this work was to observe the response of water column and sediment coliform population to the change in nutrient concentrations in the water column. Methods and Results: The survival experiments were conducted in flow-through chambers containing sandy sediments. Bovine faeces wer...

  4. The Effect of Sediment Disturbance on the Carbon and Nitrogen Cycles Within Coastal Marine Lakes

    NASA Astrophysics Data System (ADS)

    Mills, A. R.; Wilson, S. R.; Jolley, D. F.

    2006-12-01

    A system allowing the ex situ quantification of the nitrogen cycle and various carbonaceous species (Organic Carbon, carbon dioxide, methane) in the air, water and sediment has been developed and used to monitor the effects of sediment disturbance on the nitrogen and carbon cycles. Measurements are made using standard wet chemical techniques for the sediment and water phases, and FTIR spectroscopy for the real-time monitoring of gas concentrations. Sediment collected from two temperate marine lakes on the eastern coast of Australia has been examined. In the laboratory it was found that the methane flux peaked three days after the initial disturbance; nitrous oxide flux peaked after 12 days while carbon dioxide flux varied throughout the experiment. Nitrite and nitrate concentrations in the overlying water peaked at the end of the second and third weeks, respectively. The total quantity of nitrogen within the system increased by ~ 35%. Sediment disturbance led to an initial release of nitrogenous nutrients from the sediment to the overlying water that were rapidly readsorbed to sediment particles and sequestered back into the sediment phase. The same technology was also adapted to allow this research to be undertaken in the field and used to study three new temperate marine sites within Lake Illawarra, New South Wales, Australia.

  5. Concentration ratios for small mammals collected from the exposed sediments of a 137Cs contaminated reservoir.

    PubMed

    Paller, Michael H; Timothy Jannik, G; Wike, Lynn D

    2006-01-01

    (137)Cs concentration ratios were computed for small mammals collected from the dried sediments of a partially drained, contaminated reservoir. Soil (137)Cs activity concentrations were heterogeneous on small and large spatial scales and had a geometric mean of 253 (range 23-2110) Bq/kg dry weight. Mean (137)Cs activity concentrations in composite cotton rat Sigmodon hispidus and cotton mouse Peromyscus gossypinus samples averaged 2480 (range 556-6670) and 471 (range 96-1000) Bq/kg whole body dry weight, respectively. About 50% of the variance in cotton rat tissue (137)Cs activity was explained by variation in soil (137)Cs activity. Soil-to-animal dry weight concentration ratios averaged 6.0 for cotton rats and 1.2 for cotton mice and were generally similar to (137)Cs concentration ratios for herbivorous, homeothermic animals from other contaminated ecosystems. In the RESRAD-BIOTA dose model, the default wet-weight concentration ratio for (137)Cs in terrestrial animals is 110 resulting in an estimate of internal and external radiation doses to terrestrial biota that is 44 times more than the dose calculated with the actual measured wet-weight concentration ratio for cotton rats (1.6). These results show that site-specific concentration ratios can significantly affect the estimation of dose. PMID:16963166

  6. Comparison of vapor concentrations of volatile organic compounds with ground-water concentrations of selected contaminants in sediments beneath the Sudbury River, Ashland, Massachusetts, 2000

    USGS Publications Warehouse

    Campbell, J.P.; Lyford, F.P.; Willey, Richard E.

    2002-01-01

    A mixed plume of contaminants in ground water, including volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), and metals, near the former Nyanza property in Ashland, Massachusetts, discharges to the Sudbury River upstream and downstream of Mill Pond and a former mill raceway. Polyethylene-membrane vapor-diffusion (PVD) samplers were installed in river-bottom sediments to determine if PVD samplers provide an alternative to ground-water sampling from well points for identifying areas of detectable concentrations of contaminants in sediment pore water near the ground-water and surface-water interface. In August and September 2000, the PVD samplers were installed near well points at depths of 8 to 12 inches in both fine and coarse sediments, whereas the well points were installed at depths of 1 to 5 feet in coarse sediments only. Comparison between vapor and water samples at 29 locations upstream from Mill Pond show that VOC vapor concentrations from PVD samplers in coarse river-bottom sediments are more likely to correspond to ground-water concentrations from well points than PVD samplers installed in fine sediments. Significant correlations based on Kendall's Tau were shown between vapor and ground-water concentrations for trichloroethylene and chlorobenzene for PVD samplers installed in coarse sediments where the fine organic layer that separated the two sampling depths was 1 foot or less in thickness. VOC concentrations from vapor samples also were compared to VOC, SVOC, and metals concentrations from ground-water samples at 10 well points installed upstream and downstream from Mill Pond, and in the former mill raceway. Chlorobenzene vapor concentrations correlated significantly with ground-water concentrations for 5 VOCs, 2 SVOCs, and 10 metals. Trichloroethylene vapor concentrations did not correlate with any of the other ground-water constituents analyzed at the 10 well points. Chlorobenzene detected by use of PVD samplers appears to be a

  7. New Insights into Phosphorus Mobilisation from Sulphur-Rich Sediments: Time-Dependent Effects of Salinisation

    PubMed Central

    van Diggelen, Josepha M. H.; Lamers, Leon P. M.; van Dijk, Gijs; Schaafsma, Maarten J.; Roelofs, Jan G. M.; Smolders, Alfons J. P.

    2014-01-01

    Internal phosphorus (P) mobilisation from aquatic sediments is an important process adding to eutrophication problems in wetlands. Salinisation, a fast growing global problem, is thought to affect P behaviour. Although several studies have addressed the effects of salinisation, interactions between salinity changes and nutrient cycling in freshwater systems are not fully understood. To tackle eutrophication, a clear understanding of the interacting effects of sediment characteristics and surface water quality is vital. In the present study, P release from two eutrophic sediments, both characterized by high pore water P and very low pore water iron (Fe2+) concentrations, was studied in a long-term aquarium experiment, using three salinity levels. Sediment P release was expected to be mainly driven by diffusion, due to the eutrophic conditions and low iron availability. Unexpectedly, this only seemed to be the driving mechanism in the short term (0–10 weeks). In the long term (>80 weeks), P mobilisation was absent in most treatments. This can most likely be explained by the oxidation of the sediment-water interface where Fe2+ immobilises P, even though it is commonly assumed that free Fe2+ concentrations need to be higher for this. Therefore, a controlling mechanism is suggested in which the partial oxidation of iron-sulphides in the sediment plays a key role, releasing extra Fe2+ at the sediment-water interface. Although salinisation was shown to lower short-term P mobilisation as a result of increased calcium concentrations, it may increase long-term P mobilisation by the interactions between sulphate reduction and oxygen availability. Our study showed time-dependent responses of sediment P mobilisation in relation to salinity, suggesting that sulphur plays an important role in the release of P from FeSx-rich sediments, its biogeochemical effect depending on the availability of Fe2+ and O2. PMID:25369128

  8. Effects of mud sedimentation on lugworm ecosystem engineering

    NASA Astrophysics Data System (ADS)

    Montserrat, F.; Suykerbuyk, W.; Al-Busaidi, R.; Bouma, T. J.; van der Wal, D.; Herman, P. M. J.

    2011-01-01

    Benthic ecosystem engineering organisms attenuate hydrodynamic or biogeochemical stress to ameliorate living conditions. Bioturbating infauna, like the lugworm Arenicola marina, determine intertidal process dynamics by maintaining the sediment oxygenated and sandy. Maintaining the permeability of the surrounding sediment enables them to pump water through the interstitial spaces, greatly increasing the oxygen availability. In a field experiment, both lugworm presence and siltation regime were manipulated to investigate to what extent lugworms are able to cope with sedimentation of increasing mud percentage and how this would affect its ecosystem engineering. Fluorescent tracers were added to experimentally deposited mud to visualise bioturbation effects on fine sediment fractions. Lugworm densities were not affected by an increasing mud percentage in experimentally deposited sediment. Negative effects are expected to occur under deposition with significantly higher mud percentages. Surface chlorophyll a content was a function of experimental mud percentage, with no effect of lugworm bioturbation. Surface roughness and sediment permeability clearly increased by lugworm presence, whereas sediment erosion threshold was not significantly affected by lugworms. The general idea that A. marina removes fine sediment fractions from the bed could not be confirmed. Rather, the main ecosystem engineering effect of A. marina is hydraulic destabilisation of the sediment matrix.

  9. Response of Benthic Foraminiferal Size to Oxygen Concentration in Antarctic Sediment Cores

    NASA Astrophysics Data System (ADS)

    Guo, D.; Keating-Bitonti, C.; Payne, J.

    2014-12-01

    Oxygen availability is important for biological reactions and the demand of oxygen is determined by the size of the organism. Few marine organisms can tolerate low oxygen conditions, but benthic foraminifera, a group of amoeboid protists that are highly sensitive to environmental factors, are known to live in these conditions. Benthic foraminifera may be able to live in oxygen stressed environments by changing the size and shape of their test. Low oxygen concentrations should favor smaller, thinner-shelled, flattened test morphologies. We hypothesize that the volume-to-surface area ratio of benthic foraminifera will decrease with decreasing dissolved oxygen concentrations. To test this hypothesis, we picked two calcareous species (Epistominella exigua and Cassulinoides porrectus) and one agglutinated species (Portatrochammina antarctica) from three sediment cores collected from Explorer's Cove, Antarctica. Starting at the sediment-water interface, each core spans approximately 5-8 cm of depth. Profiles of dissolved oxygen concentrations were measured at the time of collection. At specific depths within the cores, we measured the three dimensions of picked foraminiferal tests using NIS-Elements. We calculated the volume and surface area of the tests assuming the shape of the foraminifers was an ellipsoid. The size trends of E. exigua confirm our hypothesis that the test volume-to-surface area ratios correlate positively with dissolved oxygen concentrations (p-value < 0.001). However, the size trends of the other species refute our hypothesis: P. antarctica shows no correlation and C. porrectus shows a negative correlation (p-value < 0.001) to dissolved oxygen concentrations. Thus, our results show that the change in size in response to variations in dissolved oxygen concentrations is species dependent. Moreover, we find that calcareous species are more sensitive to oxygen fluctuations than agglutinated species.

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

    EPA Science Inventory

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

  11. METAL-COLLOID PARTITIONING IN ARTIFICIAL INTERSTITIAL WATERS OF MARINE SEDIMENTS: INFLUENCES OF SALINITY, PH AND COLLOIDAL ORGANIC CARBON CONCENTRATION

    EPA Science Inventory

    For decades, heavy metals have been deposited into marine sediments as a result of anthropogenic activities. Depending on their bioavailability, these metals may represent a risk to benthic organisms. Dissolved interstitial water metal concentrations have been shown to be better ...

  12. [Effect of nano-TiO2 on the release and activation of mercury in sediment].

    PubMed

    Zhang, Jin-Yang; Li, Chu-Xian; Wang, Ding-Yong; Zhou, Xiong; Sun, Rong-Guo; Zhang, Cheng; Li, Liang

    2014-12-01

    To investigate the effects of nano-TiO2 on mercury release and activation in sediment, flooding simulation experiments were conducted. The impacts of nano-TiO2 on total mercury and methylmercury concentrations in overlying water were analyzed. And the influences of nano-TiO2 on the migration and transformation of mercury were discussed based on changes of mercury speciation in sediment. The results indicated that nano-TiO2 promoted the release of mercury in sediment, leading to more mercury released into the water. Compared with the control, 4 g x kg(-1) TiO2 nanoparticles increased the total mercury by 91.32%, when the concentration of total mercury in overlying water was the highest. Release of mercury in soil was increased by approximately 10% finally. The main reason may be that the dissolution of oxidation state mercury was improved by nano-TiO2. It indicated that the risk of mercury contamination in water may increase. Moreover, under the experimental conditions, nano-TiO2 may reduce the formation of methylmercury in sediment in the short-term, but no significant effects in the long-term. Generally, the effects of nano-TiO2 on the release and transformation of mercury in sediment showed concentration dependence. Thus, with increasing nano-TiO2 content in sediment or soil, its impact on the geochemical cycle of mercury may increase. PMID:25826926

  13. Nutrient and sediment concentrations and corresponding loads during the historic June 2008 flooding in eastern Iowa

    USGS Publications Warehouse

    Hubbard, L.; Kolpin, D.W.; Kalkhoff, S.J.; Robertson, D.M.

    2011-01-01

    A combination of above-normal precipitation during the winter and spring of 2007-2008 and extensive rainfall during June 2008 led to severe flooding in many parts of the midwestern United States. This resulted in transport of substantial amounts of nutrients and sediment from Iowa basins into the Mississippi River. Water samples were collected from 31 sites on six large Iowa tributaries to the Mississippi River to characterize water quality and to quantify nutrient and sediment loads during this extreme discharge event. Each sample was analyzed for total nitrogen, dissolved nitrate plus nitrite nitrogen, dissolved ammonia as nitrogen, total phosphorus, orthophosphate, and suspended sediment. Concentrations measured near peak flow in June 2008 were compared with the corresponding mean concentrations from June 1979 to 2007 using a paired t test. While there was no consistent pattern in concentrations between historical samples and those from the 2008 flood, increased flow during the flood resulted in near-peak June 2008 flood daily loads that were statistically greater (p < 0.05) than the median June 1979 to 2007 daily loads for all constituents. Estimates of loads for the 16-d period during the flood were calculated for four major tributaries and totaled 4.95 x 10(7) kg of nitrogen (N) and 2.9 x 10(6) kg of phosphorus (P) leaving Iowa, which accounted for about 22 and 46% of the total average annual nutrient yield, respectively. This study demonstrates the importance of large flood events to the total annual nutrient load in both small streams and large rivers.

  14. Baseline-contaminant metal concentrations in sediments from Lake Manzalah, Nile Delta, Egypt: Aquaculture at risk

    SciTech Connect

    Siegel, F.R.; Slaboda, M.; Bagchi, S. . Dept. of Geology); Stanley, D.J. )

    1992-01-01

    Cored sediments collected from Lake Manzalah, Egypt, December, 1990, were analyzed for 24 chemical elements. These include metals from industrial discharge that may be bioaccumulated by fish and humans. Lake Manzalah provides more than 50% of the total Egyptian food fish catch. Half of this catch is from the Ginka sub-basin which receives sewage (nutrient) and other discharge via the Bahr-El-Baqar drain. C-14 dated long cores give a sedimentation rate of 0.5 cm/yr for the study area. The 1 m cores studied may contain an environmental geochemistry log of about 200 years. Pre-industrial metal values, and rate and timing of any pollutant input to the lake can be estimated. Of seven cores analyzed, two have high concentrations for several potentially toxic metals in their upper 20 cm (Hg, 822 ppb; Pb, 110 ppm; Zn, 635 ppm; Cd, 1.3 ppm; Cu, 275 ppm; As 7 ppm; Sn, 18 ppm; Cr, 215 ppm; and others). These elements correlate among themselves and with C-org suggesting their bioavailability. This correlation level is not found between element contents and mineralogy. The discharge resulting in high metal concentrations in these lake sediments may be from between 1960 and 1970. This suggests an origin in discharge from major industries that developed after the emplacement of the High Dam at Aswan in 1964. The core with the highest metal contents is close to the outfall from the Bahr-El-Baqar drain in the Ginka aquaculture sub-basin. A second core with high metal values is 1.6 km from the outfall along the sub-basin current flow. There is potential for bioaccumulation of heavy metals to high concentrations in fish from the Gink sub-basin of Lake Manzalah. If these metals pass through the food web to humans, continuous ingestion presents a long-term health risk to consumers. Metal contents of fish from this area should be closely monitored.

  15. Nutrient and sediment concentrations and corresponding loads during the historic June 2008 flooding in eastern Iowa.

    PubMed

    Hubbard, L; Kolpin, D W; Kalkhoff, S J; Robertson, D M

    2011-01-01

    A combination of above-normal precipitation during the winter and spring of 2007-2008 and extensive rainfall during June 2008 led to severe flooding in many parts of the midwestern United States. This resulted in transport of substantial amounts of nutrients and sediment from Iowa basins into the Mississippi River. Water samples were collected from 31 sites on six large Iowa tributaries to the Mississippi River to characterize water quality and to quantify nutrient and sediment loads during this extreme discharge event. Each sample was analyzed for total nitrogen, dissolved nitrate plus nitrite nitrogen, dissolved ammonia as nitrogen, total phosphorus, orthophosphate, and suspended sediment. Concentrations measured near peak flow in June 2008 were compared with the corresponding mean concentrations from June 1979 to 2007 using a paired t test. While there was no consistent pattern in concentrations between historical samples and those from the 2008 flood, increased flow during the flood resulted in near-peak June 2008 flood daily loads that were statistically greater (p < 0.05) than the median June 1979 to 2007 daily loads for all constituents. Estimates of loads for the 16-d period during the flood were calculated for four major tributaries and totaled 4.95 x 10(7) kg of nitrogen (N) and 2.9 x 10(6) kg of phosphorus (P) leaving Iowa, which accounted for about 22 and 46% of the total average annual nutrient yield, respectively. This study demonstrates the importance of large flood events to the total annual nutrient load in both small streams and large rivers. PMID:21488505

  16. Mercury and methylmercury concentrations in Mediterranean seafood and surface sediments, intake evaluation and risk for consumers.

    PubMed

    Spada, Lucia; Annicchiarico, Cristina; Cardellicchio, Nicola; Giandomenico, Santina; Di Leo, Antonella

    2012-04-01

    Total mercury and methylmercury concentrations were measured in sediments and marine organisms from the Taranto Gulf to understand their distribution and partitioning. Sediment concentrations ranged from 0.036 to 7.730 mg/kg (mean: 2.777 mg/kg d.w.) and from 1 to 40 μg/kg (mean: 11 μg/kg d.w.) for total mercury (THg) and methylmercury (Me-Hg), respectively. In mollusks THg ranged from n.d. to 1870 μg/kg d.w. while in fish from 324 to 1740 μg/kg d.w. Me-Hg concentrations in fish ranged from 190 to 1040 μg/kg d.w. and from n.d. to 1321 μg/kg d.w. in mollusks. THg exceeded the maximum level fixed by the European Commission (0.5 mg/kg w.w.) only in gastropod Hexaplex t. The calculated weekly intake was in many cases over the Provisional Tolerable Weekly Intake established by EFSA for all edible species. These results seem to indicate that dietary consumption of this seafood implicates an appreciable risk for human health. PMID:21968333

  17. Ratios of total suspended solids to suspended sediment concentrations by particle size

    USGS Publications Warehouse

    Selbig, W.R.; Bannerman, R.T.

    2011-01-01

    Wet-sieving sand-sized particles from a whole storm-water sample before splitting the sample into laboratory-prepared containers can reduce bias and improve the precision of suspended-sediment concentrations (SSC). Wet-sieving, however, may alter concentrations of total suspended solids (TSS) because the analytical method used to determine TSS may not have included the sediment retained on the sieves. Measuring TSS is still commonly used by environmental managers as a regulatory metric for solids in storm water. For this reason, a new method of correlating concentrations of TSS and SSC by particle size was used to develop a series of correction factors for SSC as a means to estimate TSS. In general, differences between TSS and SSC increased with greater particle size and higher sand content. Median correction factors to SSC ranged from 0.29 for particles larger than 500m to 0.85 for particles measuring from 32 to 63m. Great variability was observed in each fraction-a result of varying amounts of organic matter in the samples. Wide variability in organic content could reduce the transferability of the correction factors. ?? 2011 American Society of Civil Engineers.

  18. Exploring the uncertainty in attributing sediment contributions in fingerprinting studies due to uncertainty in determining element concentrations in source areas.

    NASA Astrophysics Data System (ADS)

    Gomez, Jose Alfonso; Owens, Phillip N.; Koiter, Alex J.; Lobb, David

    2016-04-01

    One of the major sources of uncertainty in attributing sediment sources in fingerprinting studies is the uncertainty in determining the concentrations of the elements used in the mixing model due to the variability of the concentrations of these elements in the source materials (e.g., Kraushaar et al., 2015). The uncertainty in determining the "true" concentration of a given element in each one of the source areas depends on several factors, among them the spatial variability of that element, the sampling procedure and sampling density. Researchers have limited control over these factors, and usually sampling density tends to be sparse, limited by time and the resources available. Monte Carlo analysis has been used regularly in fingerprinting studies to explore the probable solutions within the measured variability of the elements in the source areas, providing an appraisal of the probability of the different solutions (e.g., Collins et al., 2012). This problem can be considered analogous to the propagation of uncertainty in hydrologic models due to uncertainty in the determination of the values of the model parameters, and there are many examples of Monte Carlo analysis of this uncertainty (e.g., Freeze, 1980; Gómez et al., 2001). Some of these model analyses rely on the simulation of "virtual" situations that were calibrated from parameter values found in the literature, with the purpose of providing insight about the response of the model to different configurations of input parameters. This approach - evaluating the answer for a "virtual" problem whose solution could be known in advance - might be useful in evaluating the propagation of uncertainty in mixing models in sediment fingerprinting studies. In this communication, we present the preliminary results of an on-going study evaluating the effect of variability of element concentrations in source materials, sampling density, and the number of elements included in the mixing models. For this study a virtual

  19. The effect of tidal forcing on biogeochemical processes in intertidal salt marsh sediments

    PubMed Central

    Taillefert, Martial; Neuhuber, Stephanie; Bristow, Gwendolyn

    2007-01-01

    Background Early diagenetic processes involved in natural organic matter (NOM) oxidation in marine sediments have been for the most part characterized after collecting sediment cores and extracting porewaters. These techniques have proven useful for deep-sea sediments where biogeochemical processes are limited to aerobic respiration, denitrification, and manganese reduction and span over several centimeters. In coastal marine sediments, however, the concentration of NOM is so high that the spatial resolution needed to characterize these processes cannot be achieved with conventional sampling techniques. In addition, coastal sediments are influenced by tidal forcing that likely affects the processes involved in carbon oxidation. Results In this study, we used in situ voltammetry to determine the role of tidal forcing on early diagenetic processes in intertidal salt marsh sediments. We compare ex situ measurements collected seasonally, in situ profiling measurements, and in situ time series collected at several depths in the sediment during tidal cycles at two distinct stations, a small perennial creek and a mud flat. Our results indicate that the tides coupled to the salt marsh topography drastically influence the distribution of redox geochemical species and may be responsible for local differences noted year-round in the same sediments. Monitoring wells deployed to observe the effects of the tides on the vertical component of porewater transport reveal that creek sediments, because of their confinements, are exposed to much higher hydrostatic pressure gradients than mud flats. Conclusion Our study indicates that iron reduction can be sustained in intertidal creek sediments by a combination of physical forcing and chemical oxidation, while intertidal mud flat sediments are mainly subject to sulfate reduction. These processes likely allow microbial iron reduction to be an important terminal electron accepting process in intertidal coastal sediments. PMID:17567893

  20. Passive equilibrium sampler for in situ measurements of freely dissolved concentrations of hydrophobic organic chemicals in sediments.

    PubMed

    Witt, Gesine; Lang, Susann-Cathrin; Ullmann, Dagny; Schaffrath, Gotja; Schulz-Bull, Detlef; Mayer, Philipp

    2013-07-16

    In this study, an equilibrium passive sampling device is introduced that facilitates the in situ measurement of hydrophobic organic chemicals bioavailability in sediments in terms of freely dissolved concentrations. The new field sampler allows SPME fibers and silicone hollow fibers to be immersed and equilibrated in situ, whereas an automated liner exchanger (ALEX) facilitates the quantitative transfer of analytes to the GC without the use of extraction solvents. The sampler was developed for environmental monitoring as follows: (1) It is of very solid construction and can be reused practically ad infinitum. (2) Fibers with varying surface to volume ratios can be exposed in parallel in order to confirm that equilibrium was reached between sampler and sediment. (3) The equilibrium times allow a temporal resolution that is suited for monitoring of both long-term trends and seasonal effects. The automated thermal desorption reduced sample treatment to a minimum and ensured cost- and time-efficient measurements while minimizing potential error sources after the sampling. The sampler is applicable in a multitude of aquatic environments, especially where currents are low and sediments are muddy and well-mixed, e.g. by bioturbation. Examples for such environments are mud flats, harbor basins, river banks, and lakes. PMID:23819657

  1. Estimation of Biota Sediment Accumulation Factor (BSAF) from Paired Observations of Chemical Concentrations in Biota and Sediment (External Review Draft)

    EPA Science Inventory

    This report was written in response to a March 2004 request from EPA's Ecological Risk Assessment Forum (ERAF) for information about estimating Biota-Sediment Accumulation Factors (BSAFs). BSAF is a parameter describing bioaccumulation of sediment-associated organic compounds or...

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

    PubMed

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

    2014-08-30

    Surface sediments were collected from sixteen locations in order to assess levels and sources of polycyclic aromatic hydrocarbons (PAHs) in sediments of Qatar exclusive economic zone (EEZ). Samples were analyzed for 16 parent PAHs, 18 alkyl homologs and for dibenzothiophenes. Total PAHs concentration (∑PAHs) ranged from 2.6 ng g(-1) to 1025 ng g(-1). The highest PAHs concentrations were in sediments in and adjacent to harbors. Alkylated PAHs predominated most of the sampling locations reaching up to 80% in offshore locations. Parent PAHs and parent high molecular weight PAHs dominated location adjacent to industrial activities and urban areas. The origin of PAHs sources to the sediments was elucidated using ternary plot, indices, and molecular ratios of specific compounds such as (Ant/Phe+Ant), (Flt/Flt+Pyr). PAHs inputs to most coastal sites consisted of mixture of petroleum and combustion derived sources. However, inputs to the offshore sediments were mainly of petroleum origin. PMID:24798421

  3. Effects of carbon and nitrate on denitrification in bottom sediments of an effluent-dominated river

    USGS Publications Warehouse

    Bradley, P.M.; McMahon, P.B.; Chapelle, F.H.

    1995-01-01

    Nitrogen and carbon limitation of denitrification in the bed sediments of an effluent-dominated stream were investigated by quantifying the effects of nitrate and glucose additions on the rate of sediment N2O production. Bed sediment samples were collected from a 30-km stretch of the South Platte River where up to 95% of the base flow discharge consists of effluent from a water treatment plant in Denver, Colorado. The rate of denitrification in upstream sediment samples incubated under in situ nitrate and carbon conditions was primarily limited by nitrate supply. The stimulatory effect of nitrate additions on the rate of bed sediment denitrification decreased with increasing distance downstream of the treatment plant. Approximately 35 km downstream of the treatment plant, denitrification in the bed sediment samples was carbon limited. The observed decreases in the concentration of total inorganic nitrogen (as NH4 + NO3) dissolved in the river and the organic carbon content of the bed sediments with increasing distance downstream of the treatment plant suggest that bed sediment denitrification is a significant sink for nitrogen in this stretch of the river.

  4. Predicting the toxicity of metal-contaminated field sediments using interstitial concentration of metals and acid-volatile sulfide normalizations

    SciTech Connect

    Hansen, D.J.; Berry, W.J.; Mahony, J.D.

    1996-12-01

    The authors investigated the utility of interstitial water concentrations of metals and simultaneously extracted metal/acid-volatile sulfide (SEM/AVS) ratios to explain the biological availability of sediment-associated divalent metals to benthic organisms exposed in the laboratory to sediments from five saltwater and four freshwater locations in the US, Canada, and China. The amphipod Ampelisca abdita or the polychaete Neanthes arenaceodentata were exposed to 70 sediments from the five saltwater locations, and the amphipod Hyalella azteca or the oligochaete Lumbriculus variegatus were exposed to 55 sediments from four freshwater locations in 10-d lethality tests. Almost complete absence of toxicity in spiked sediments and field sediments where metals were the only known source of contamination and where interstitial water toxic units (IWTUs) were < 0.5 indicates that toxicity associated with sediments having SEM/AVS ratios < 1.0 from two saltwater locations in industrial harbors was not metals-related as these sediments contained <0.5 IWTU. Metals-associated toxicity was absent in 100% of sediments from the remaining three saltwater field locations, where metals were the only known source of contamination and SEM/AVS ratios were {le} 1.0. Two-thirds of 45 sediments from seven saltwater and freshwater field locations having both IWTUs > 0.5 (55%) were used alone. The difference between the molar concentrations of SEM and AVS (SEM-AVS) can provide important insight into the extent of additional available binding capacity, the magnitude by which AVS binding has been exceeded, and, when organism response is considered, the potential magnitude of importance of other metal binding phases. SEM-AVS should be used instead of SEM/AVS ratios as a measure of metals availability. In published experiments with both metal-spiked and field sediments, SEM-AVS and IWTUs accurately identified absence of sediment toxicity and with less accuracy identified the presence of toxicity.

  5. Influence of mining-related activities on concentrations of metals in water and sediment from streams of the Black Hills, South Dakota

    USGS Publications Warehouse

    May, T.W.; Wiedmeyer, R.H.; Gober, J.; Larson, S.

    2001-01-01

    Water and sediment samples were collected from streams in Spearfish Creek, Whitewood Creek, and Bear Butte Creek watersheds in the Black Hills, SD, an area impacted by gold mining operations. Arsenic concentrations that exceeded the U.S. Environmental Protection Agency's Maximum Concentration Limit of 50 ??g/L for drinking water were found in water from Annie Creek, a tributary of Spearfish Creek, and from Whitewood Creek. Gold Run, a tributary of Whitewood Creek, and Annie Creek contained Se concentrations in water that exceeded the EPA Ecotox threshold of 5 ??g/L and were classified as a high hazard for Se accumulation from water into the planktonic food chain and for resultant toxicity to fish and aquatic birds. Concentrations of As, Cd, Cu, Hg, Ni, Pb, and Zn in sediment exceeded EPA Ecotox thresholds in one or more of the watersheds suggesting potential adverse ecological effects. Sediment from Rubicon Creek, a tributary of Spearfish Creek, contained Se concentrations high enough (4.0 ??g/g) to be a moderate hazard for accumulation from sediments into the benthic food chain, with resultant dietary toxicity to fish and aquatic birds. These results are discussed in light of historical mining activities and recent clean-up and reclamation efforts. Based on the results and comparisons to Ecotox tresholds, further studies of ecological effects are warranted.

  6. Suspended-sediment concentrations, loads, total suspended solids, turbidity, and particle-size fractions for selected rivers in Minnesota, 2007 through 2011

    USGS Publications Warehouse

    Ellison, Christopher A.; Savage, Brett E.; Johnson, Gregory D.

    2014-01-01

    Sediment-laden rivers and streams pose substantial environmental and economic challenges. Excessive sediment transport in rivers causes problems for flood control, soil conservation, irrigation, aquatic health, and navigation, and transports harmful contaminants like organic chemicals and eutrophication-causing nutrients. In Minnesota, more than 5,800 miles of streams are identified as impaired by the Minnesota Pollution Control Agency (MPCA) due to elevated levels of suspended sediment. The U.S. Geological Survey, in cooperation with the MPCA, established a sediment monitoring network in 2007 and began systematic sampling of suspended-sediment concentrations (SSC), total suspended solids (TSS), and turbidity in rivers across Minnesota to improve the understanding of fluvial sediment transport relations. Suspended-sediment samples collected from 14 sites from 2007 through 2011 indicated that the Zumbro River at Kellogg in the driftless region of southeast Minnesota had the highest mean SSC of 226 milligrams per liter (mg/L) followed by the Minnesota River at Mankato with a mean SSC of 193 mg/L. During the 2011 spring runoff, the single highest SSC of 1,250 mg/L was measured at the Zumbro River. The lowest mean SSC of 21 mg/L was measured at Rice Creek in the northern Minneapolis- St. Paul metropolitan area. Total suspended solids (TSS) have been used as a measure of fluvial sediment by the MPCA since the early 1970s; however, TSS concentrations have been determined to underrepresent the amount of suspended sediment. Because of this, the MPCA was interested in quantifying the differences between SSC and TSS in different parts of the State. Comparisons between concurrently sampled SSC and TSS indicated significant differences at every site, with SSC on average two times larger than TSS concentrations. The largest percent difference between SSC and TSS was measured at the South Branch Buffalo River at Sabin, and the smallest difference was observed at the Des Moines

  7. Sediment mixing and accumulation rate effects on radionuclide depth profiles in Hudson estuary sediments

    SciTech Connect

    Olsen, C.R.; Simpson, H.J.; Peng, T.; Bopp, R.F.; Trier, R.M.

    1981-11-20

    Measured anthropogenic radionuclide profiles in sediment cores from the Hudson River estuary were compared with profiles computed by using known input histories of radionuclides to the estuary and mixing coefficients which decreased exponentially with depth in the sediment. Observed /sup 134/Cs sediment depth profiles were used in the mixing rate computation because reactor releases were the only significant source for this nuclide, whereas the inputs of /sup 137/Cs and /sup 239.240/Pu to the estuary were complicated by runoff or erosion in upstream areas, in addition to direct fallout from precipitation. Our estimates for the rates of surface sediment mixing in the low salinity reach of the estuary range from 0.25 to 1 cm/sup 2//yr, or less. In some areas of the harbor adjacent to New York City, were fine-particle accumulation rates are generally >3 cm/yr, and often as high as 10 to 20 cm/yr, sediment mixing rates as high as 10 cm/sup 2//yr would have little effect on radionuclide peak distributions. Consequently, anthropogenic radionuclide maximum activities in subsurface sediments of the Hudson appear to be useful as time-stratigraphic reference levels, which can be correlated with periods of maximum radionuclide inputs for estimating rates and patterns of sediment accumulation.

  8. An estimate of the influence of sediment concentration and type on remote sensing penetration depth for various coastal waters

    NASA Technical Reports Server (NTRS)

    Whitlock, C. H.

    1976-01-01

    Under the assumptions of collimated light, a homogenous water column, zero molecular scattering, and constant ratio of volume scattering function to scattering coefficient, estimates of the remote sensing depth parameter, Z90, are made for various coastal waters at 540 nm. Calculations indicate that sediment concentration and type have a strong influence on remote sensing depth when concentrations are below 5 mg/theta. Above 5 mg/theta, the absorption coefficient of the sediments becomes large in comparison to that of water, causing Z90 values to be less than 2 m with only small differences between various sediment types.

  9. Brominated flame retardants in Korean river sediments, including changes in polybrominated diphenyl ether concentrations between 2006 and 2009.

    PubMed

    Lee, In-Seok; Kang, Hee-Hyung; Kim, Un-Jung; Oh, Jeong-Eun

    2015-05-01

    Brominated flame retardants were analyzed in sediment samples from the Nakdong River basin, Korea. The total concentrations of the 27 polybrominated diphenyl ethers (PBDEs), including decabrominated diphenyl ether (BDE 209), analyzed were 0.55-300 ng g(-1) dry weight (dw), the BDE 209 concentrations were 0.39-190 ng g(-1) dw, the tetrabromobisphenol A (TBBPA) concentrations were 0.05-150 ng g(-1) dw, and the total hexabromocyclododecane (sum of α-, β-, γ-HBCDs) concentrations were 0.11-19 ng g(-1) dw. The PBDE and HBCD concentrations were comparable to or lower than the concentrations found in sediments from other countries, whereas the TBBPA concentrations were comparable to or higher than the concentrations found in other countries. The TBBPA concentrations were similar to or lower than the PBDE concentrations, even though more than twice as much TBBPA as total PBDEs is consumed in Korea, and this phenomenon was probably caused by TBBPA and PBDEs being used differently during the manufacture of products, and their different half-lives in sediment and affinities for the particle phase in aquatic environments. Sediment samples from several sampling sites close to facilities where expandable polystyrene, epoxy, and polycarbonate resins are manufactured and handled had relatively high TBBPA and HBCD concentrations. Temporal changes in the PBDE concentration strongly correlated with temporal variations in the geochemical compositions such as total organic carbon content and grain size value of the sediment. The PBDE and HBCD distribution profiles in the sediment samples indicated that commercial PBDE and HBCD products were released locally. PMID:25655576

  10. Sediment erodability in sediment transport modelling: Can we account for biota effects?

    NASA Astrophysics Data System (ADS)

    Le Hir, P.; Monbet, Y.; Orvain, F.

    2007-05-01

    Sediment erosion results from hydrodynamic forcing, represented by the bottom shear stress (BSS), and from the erodability of the sediment, defined by the critical erosion shear stress and the erosion rate. Abundant literature has dealt with the effects of biological components on sediment erodability and concluded that sediment processes are highly sensitive to the biota. However, very few sediment transport models account for these effects. We provide some background on the computation of BSS, and on the classical erosion laws for fine sand and mud, followed by a brief review of biota effects with the aim of quantifying the latter into generic formulations, where applicable. The effects of macrophytes, microphytobenthos, and macrofauna are considered in succession. Marine vegetation enhances the bottom dissipation of current energy, but also reduces shear stress at the sediment-water interface, which can be significant when the shoot density is high. The microphytobenthos and secreted extracellular polymeric substances (EPS) stabilise the sediment, and an increase of up to a factor of 5 can be assigned to the erosion threshold on muddy beds. However, the consequences with respect to the erosion rate are debatable since, once the protective biofilm is eroded, the underlying sediment probably has the same erosion behaviour as bare sediment. In addition, the development of benthic diatoms tends to be seasonal, so that stabilising effects are likely to be minimal in winter. Macrofaunal effects are characterised by extreme variability. For muddy sediments, destabilisation seems to be the general trend; this can become critical when benthic communities settle on consolidated sediments that would not be eroded if they remained bare. Biodeposition and bioresuspension fluxes are mentioned, for comparison with hydrodynamically induced erosion rates. Unlike the microphytobenthos, epifaunal benthic organisms create local roughness and are likely to change the BSS generated

  11. [Concentrations and Distribution of Metals in the Core Sediments from Estuary and City Section of Liaohe River].

    PubMed

    Wang, Wei-jie; Zhou, Jun-li; Pei, Shu-wei; Liu, Zheng-tao

    2016-01-15

    The particle size, total organic carbon (TOC), total nitrogen (TN), C/N ratio and metal concentrations as well as activities of 210Pb were determined in Liaohe River estuary area (LN-2) and Shenyang area (LN-5), and the organic matter resources were discussed in two core sediments. Also the index of geoaccumulation (Igeo) and enrichment factors (EFs) methods were applied to evaluate the state of heavy metal contamination in the studied sties. The study showed that both sediment cores LN-2 and LN-5 were dominated by silts, and the vertical variations of grain-size composition and organic matter were well distributed in LN- 2 while fluctuated in LN-5. According to the organic matter source analysis through C/N ratio, C/N ratio varied in the scale of 5. 24-7.93 in LN-2 which was dominated by river source, and 9.94-14.21 in LN-5 which was dominated by terrestrial input. Al, Ca, Fe, Mn, Ni, Cu, Zn, Cd, Pb and Cr in two sediment cores had different vertical changing rules, Ni and Zn in LN-2 as well as Pb and Zn in LN-5 were affected by both natural and human factors, other elements had similar distributions to those of organic matters, which showed that these elements were mainly affected by the natural activities. Based on Igeo and EFs, both sediment cores were more severely polluted with Ni, Zn and Pb than other metals. The effects of human activities on the environment were also discussed in this study, combined with the economical development of Liaoning Province and the studied sites in the past 20 years. PMID:27078953

  12. Fine sediment sources in conservation effects assessment project watersheds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two naturally occurring radionuclides, 7Be and 210Pbxs , were used as tracers to discriminate eroded surface soils from channel-derived sediments in the fine suspended sediment loads of eight Conservation Effects Assessment Project (CEAP) benchmark watersheds. Precipitation, source soils, and suspe...

  13. Spatial variations in polycyclic aromatic hydrocarbons concentrations at surface sediments from the Cyprus (Eastern Mediterranean): relation to ecological risk assessment.

    PubMed

    Darılmaz, Enis; Kontaş, Aynur; Uluturhan, Esin; Akçalı, Idil; Altay, Oya

    2013-10-15

    The objective of the present study was to evaluate the distribution, sources, origins, and environmental risk assessment of polycyclic aromatic hydrocarbons (16 US EPA priority pollutants) pollution in 23 surface sediments from Cyprus coast. The mean total polycyclic aromatic hydrocarbons (PAHs) concentrations in the sediments from Gemi Konagi, Girne and Gazi Magusa areas were found 47, 52 and 50 ng/g, respectively. Molecular ratios and principle component analysis indicated that PAH pollution originated mainly from fossil sources, with higher pyrolytic contributions. The 2-3 ring PAHs were dominant in Cyprus sediments. Concentrations of PAHs observed in this study were compared with available soil quality guidelines and the concentrations were lower than the guideline values. The guideline values suggested that the Cyprus sediments were likely to be not contaminated by toxic PAH compounds. PMID:23948089

  14. Acetate in recent anoxic sediments: Direct and indirect measurements of concentration and turnover rates

    NASA Astrophysics Data System (ADS)

    Shaw, David G.; McIntosh, Douglas J.

    1990-12-01

    While acetate is generally regarded as an important intermediate in the mineralization of organic matter in anoxic sediment systems, some quantitative studies in marine systems (including our own) have measured acetate oxidation rates in excess of sulphate reduction rates where sulphate is known to be the principal electron acceptor. We revisited Skan Bay, Alaska, where we had previously made such observations, for a reexamination of acetate turnover. Measurements of acetate concentrations, production rate, oxidation rate and sulphate reduction rate as well as bioenergetic considerations led to the conclusion that acetate oxidation rate in 15-18-cm deep sediment is 1·1-1·5 μM h -1. The possibility that previous measurements were high because of a non-citric-acid-cycle pathway of acetate oxidation (suggested by recent laboratory studies) was excluded. It appears that our previous turnover measurements were high mainly because of high acetate concentrations. Procedures used for the isolation of porewater for acetate determination may influence results to an extent not previously recognized.

  15. Suspended sediment concentration and particle size distribution, and their relationship with heavy metal content

    NASA Astrophysics Data System (ADS)

    Sadeghi, S. H. R.; Harchegani, M. Kiani; Younesi, H. A.

    2012-02-01

    This paper aims at assessing the feasibility of suspended sediment concentration (SSC) estimation by using predictor variables of heavy metal concentration (HMC, viz., iron, chromium, zinc and nickel) transported in solution and solid. The study was conducted in the Research and Educational Forest Watershed of the Tarbiat Modares University (Kojour) which comprises an area of ca. 50000 ha. For this study, suspended sediment samples were collected from the left bank of the Kojour River twice a week, as well as during runoff events from November 2007 to June 2008. The samples were then prepared through direct digestion and finally analyzed by atomic absorption spectrophotometry (AAS). The relationship between SSC and particle size distribution (PSD) were correlated with HMC by using bivariate and multivariate regression models. Proposed models were then selected based on statistical criteria. The results showed high correlation between dissolved and particulate chromium content with efficiency coefficients beyond 77% ( P < 0.001). However, a lower relationship was found between SSC and nickel content. From these results, it is clearly shown that the HMC can practically be estimated by SSC in watersheds with different accuracy and vice versa. It is also understood that heavy metal pollution can be easily managed by controlling SSC.

  16. 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. PMID:26313755

  17. Concentrations and profiles of PCDD/Fs in sediments of major Polish rivers and the Gdansk Basin--Baltic Sea.

    PubMed

    Niemirycz, Elżbieta; Jankowska, Daria

    2011-10-01

    The present state of contamination of bottom sediments in southern part of the Baltic Sea with PCDD/Fs was compared to the findings made for the north-western and eastern Baltic Sea coastal areas of Finland, Sweden and Denmark. The extent of the study area--from marine the Gdańsk Basin, the lower Oder and Vistula Rivers up till Włocławek reservoir--allowed to obtain the sediment samples with diversified properties. Dioxin's concentrations in sediments examined in the Polish costal area allows us to evaluate this zone as relatively less contaminated. Higher dioxin concentration has been found in Wloclawek Dam Reservoir. Differences in congener patterns and temporal changes in marine sediment profiles were examined. The highest concentrations of tetra- and penta-congeners still remain in the surface layer of Gdansk Deep, whereas the decline in concentrations of these most toxic congeners, have been observed in the sediments from some other parts of the Baltic coast. Excess concentration of dioxins in sediments has a great impact on human being due to special ability of accumulation in the trophic chain as well as in water (fishes) and land (milk, meat). PMID:21917292

  18. Application of empirical model to predict background metal concentration in mixed carbonate-alumosilicate sediment (Adriatic Sea, Croatia).

    PubMed

    Felja, Igor; Romić, Marija; Romić, Davor; Bakić, Helena; Pikelj, Kristina; Juračić, Mladen

    2016-05-15

    A 96m long sediment core (S10-33) from the Mali Ston Channel (Adriatic Sea) showed large natural variation in carbonate share (between 1% and 95%) and concentration of elements. These variations indicate rather significant changes in fine-grained sediment that was deposited in this area during Younger Pleistocene and Holocene. Unaffected by anthropogenic influence, sediment in the core was used to determine background concentration of trace elements in sediment with various carbonate content. Here we propose a method of the normalization of trace elements to carbonate share, in order to assess natural/background concentration of metals in sediments consisting of carbonates and alumosilicates in various proportions. Six characteristic metals (Co, Cr, Cu, Ni, Pb, and Zn) that were normalized to carbonate share showed very good correlation, with much higher background concentrations in alumosilicate than in carbonate end member. Simple formulas were proposed to easily determine background concentration of these elements, in coastal and shelf depositional environments with mixed carbonate-alumosilicate sediments. PMID:26975609

  19. Sediment-transport characteristics and effects of sediment transport on benthic invertebrates in the Fountain Creek drainage basin upstream from Widefield, southeastern Colorado, 1985-88

    USGS Publications Warehouse

    Von Guerard, Paul

    1989-01-01

    Sediment and benthic-invertebrate data were collected during water years 1985 through 1988 in the Fountain Creek drainage basin upstream from Widefield, Colorado. Sediment data collected include suspended-sediment concentrations and particle size analysis of suspended sediment, bedload, and bed material. Sediment-transport equations were derived for total suspended-sediment discharge and suspended-sand discharge at seven periodic sampling sites. Annual suspended-sediment loads for water years 1985 through 1988 and mean suspended-sediment yields were computed for the seven periodic sampling sites. Mean annual suspended-sediment yield for 1985 through 1988 increased about 73% downstream in the Fountain Creek drainage basin primarily as a result of sediment discharging from Monument Creek. Bedload discharge was computed at six of the periodic sampling sites and ranged from 2.6 to 3,570 tons/day. Bedload discharge, as a percentage of total sediment discharge, ranged from 6 to 92%, and the smaller values occurred during rainfall runoff. Number of taxa, species density, and similarity indices were determined for benthic invertebrates at five of the periodic sampling sites. Multiple comparison tests were used to test for similarity of benthic invertebrates between the five sites. Multiple-regression analysis was done to determine the effects of sediment transport on benthic-invertebrate densities. Median grain size of bed material collected in conjunction with benthic- invertebrate samples and flooding during the 30 days prior to sampling consistently accounted for the most variation in mean densities of total organisms and major taxa groups sampled. (USGS)

  20. Spatiotemporal Trends Analysis of Pyrethroid Sediment Concentrations Spanning 10 Years in a Residential Creek in California.

    PubMed

    Hall, Lenwood W; Anderson, Ronald D; Killen, William D

    2016-02-01

    The objective of this study was to assess temporal and spatial trends for eight pyrethroids monitored in sediment spanning 10 years from 2006 to 2015 in a residential stream in California (Pleasant Grove Creek). The timeframe for this study included sampling 3 years during a somewhat normal non-drought period (2006-2008) and 3 years during a severe drought period (2013-2015). Regression analysis of pyrethroid concentrations in Pleasant Grove Creek for 2006, 2007, 2008, 2012, 2013, 2014, and 2015 using ½ the detection limit for nondetected concentrations showed statistically significant declining trends for cyfluthrin, cypermethrin, deltamethrin, permethrin, and total pyrethoids. Additional trends analysis of the Pleasant Grove Creek pyrethroid data using only measured concentrations, without nondetected values, showed similar statistically significant declining trends for cyfluthrin, cypermethrin, deltamethrin, esfenvalerate, fenpropathrin, permethrin, and total pyrethroids. Spatial trends analysis for the specific creek sites showed that six of the eight pyrethroids had a greater number of sites with statistically significant declining concentrations. Possible reasons for reduced pyrethroid concentrations in the stream bed in Pleasant Grove Creek during this 10-year period are label changes in 2012 that reduced residential use and lack of precipitation during the later severe drought years of 2013-2015. PMID:26643307

  1. Sodium chloride concentration determines exoelectrogens in anode biofilms occurring from mangrove-grown brackish sediment.

    PubMed

    Miyahara, Morio; Kouzuma, Atsushi; Watanabe, Kazuya

    2016-10-01

    Single-chamber microbial fuel cells (MFCs) were inoculated with mangrove-grown brackish sediment (MBS) and continuously supplied with an acetate medium containing different concentrations of NaCl (0-1.8M). Different from MFCs inoculated with paddy-field soil (high power outputs were observed between 0.05 and 0.1M), power outputs from MBS-MFCs were high at NaCl concentrations from 0 to 0.6M. Amplicon-sequence analyses of anode biofilms suggest that different exoelectrogens occurred from MBS depending on NaCl concentrations; Geobacter occurred abundantly below 0.1M, whereas Desulfuromonas was abundant from 0.3M to 0.6M. These results suggest that NaCl concentration is the major determinant of exoelectrogens that occur in anode biofilms from MBS. It is also suggested that MBS is a potent source of microbes for MFCs to be operated in a wide range of NaCl concentrations. PMID:27420153

  2. Guidelines for Assessing Sediment-Related Effects of DAM Removal

    NASA Astrophysics Data System (ADS)

    Greimann, B. P.; Randle, T.; Bountry, J.

    2010-12-01

    Dam removal is becoming more common in the United States as dams age and environmental concerns increase. Sediment management is an important part of many dam removal projects, but there are no commonly accepted methods to assess the level of risk associated with sediment stored behind dams. Therefore, the interagency Subcommittee on Sedimentation (SOS) is sponsoring the development of a decision framework for assessing sediment-related effects from dam removals. The decision framework provides guidance on the level of sediment data collection, analysis, and modeling needed for reservoir sediment management. The framework is based on criteria which scale the characteristics of the reservoir sediment to sediment characteristics of the river on which the reservoir is located. To assist with the framework development, workshops of invited technical experts from around the United States were convened October 2008 in Portland, Oregon and October 2009 in State College, Pennsylvania. The decision framework developed at these workshops is currently being validated with actual dam-removal case studies from across the United States including small, medium, and large reservoir sediment volumes. This paper provides the latest thinking on key components of the guidelines. The paper represents contributions from over 26 entities who have participated in the development of the guidelines. After completion of the case study application, the framework will be finalized and published.

  3. Inhibition Effect of Secondary Phosphate Mineral Precipitation on Uranium Release from Contaminated Sediments

    SciTech Connect

    Shi, Zhenqing; Liu, Chongxuan; Zachara, John M.; Wang, Zheming; Deng, Baolin

    2009-11-01

    The inhibitory effect of phosphate mineral precipitation on uranium release was evaluated using a U(VI)-contaminated sediment collected from the US Department of Energy (DOE) Hanford site. The sediment contained U(VI) that was associated with diffusion-limited intragrain regions within its mm-size granitic lithic fragments. The sediment was first treated to promote phosphate mineral precipitation in batch suspensions spiked with 1 and 50 mM aqueous phosphate, and calcium in a stoichiometric ratio of mineral hydroxyapatite. The phosphate-treated sediment was then leached to solubilize contaminant U(VI) in a column system using a synthetic groundwater that contained chemical components representative of Hanford groundwater. Phosphate treatment significantly decreased the extent of U(VI) release from the sediment. Within the experimental duration of about 200 pore volumes, the effluent U(VI) concentrations were consistently lower by over one and two orders of magnitude after the sediment was treated with 1 and 50 mM of phosphate, respectively. Measurements of solid phase U(VI) using various spectroscopes and chemical extraction of the sediment collectively indicated that the inhibition of U(VI) release from the sediment was caused by: 1) U(VI) adsorption to the secondary phosphate precipitates and 2) the transformation of initially present U(VI) mineral phases to less soluble forms.

  4. Concentrations of chlorinated organic compounds in biota and bed sediment in streams of the lower San Joaquin River drainage, California

    USGS Publications Warehouse

    Brown, Larry R.

    1998-01-01

    Samples of resident biota and bed sediments were collected in 1992 from 18 sites on or near the floor of the San Joaquin Valley, California, for analysis of 33 organochlorine compounds. The sites were divided into five groups on the basis of physiographic region and land use. Ten compounds were detected in tissue, and 16 compounds were detected in bed sediment. The most frequently detected compound in both media was p,p'-DDE. Concentrations of total DDT (sum of o,p'- and p,p'-forms of DDD, DDE, and DDT) were statistically different among groups of sites for tissue and sediment (Kruskal-Wallis, P < 0.05). Concentrations in both media were highest in streams draining the west side of the valley. Concentrations of total DDT in tissue were significantly correlated with specific conductance, pH, and total alkalinity (P < 0.05), which are indicators of the proportion of irrigation-return flows in stream discharge. Concentrations in sediment on a dry-weight basis were not correlated with these water-quality parameters, but total-organic- carbon (TOC) normalized concentrations were significantly correlated with specific conductance and pH (P < 0.05). Regressions of the concentration of total DDT in tissue as a function of total DDT in bed sediment were significant and explained as much as 76 percent of the variance in the data. The concentration of total DDT in sediment may be related to mechanisms of soil transport to surface water with bioavailability of compounds related to the concentration of TOC in sediment.

  5. Quartz concentration as an index of sediment mixing: hydraulic mine-tailings in the Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Allan James, L.

    1991-06-01

    Hydraulic gold mining delivered large volumes of sediment to northern California stream channels from 1853 to 1884. Distinctive quartz compositions of this sediment allow development of a sediment mixing index for determination of tailings concentrations in contemporaneous and reworked deposits. This index reveals patterns of sediment mixing in the Bear River, California over the last 100 years. A conceptual model summarizes the nature of sediment mixing in the Bear River basin through time and space. High terrace sediment compositions suggest that hydraulic mining sediment was diluted by about 22% other alluvium as it moved more than 60 km to the Sacramento Valley. This substantial volume of other alluvium was introduced during the mining period by human activities in addition to hydraulic mining. Sediment compositions in modern low-flow channels indicate that most channel reaches within the mining districts remain dominated by tailings due to sustained reworking of stored alluvium. Tailings are substantially diluted downstream in modern channel deposits, however, due to trapping of sediment by dams and local erosion of Quarternary alluvium.

  6. Timber Harvest Effects on Sediment and Water Yields and Analysis of Sediment Load Calculation Methods in the Interior Pacific Northwest

    NASA Astrophysics Data System (ADS)

    Elverson, C.; Karwan, D. L.

    2015-12-01

    Timber harvest practices have a long-standing association with changes in water and sediment yields. We quantify the trends in water and sediment yields in the Mica Creek Experimental Watershed (MCEW) in relation to management practices with linear regression and analysis of covariance (ANCOVA). From 1991 to 2013, an increase in water yield resulted from both clearcutting and thinning treatments, with monthly water yield rate increases of 13-57% and annual water yield increases up to 210 mm (40%) in the clearcut watershed. Following treatment, annual sediment yields increased in the clearcut watershed by 40-131% and the thinned watershed by 33-163%, both relative to the control watershed, with statistically-significant monthly load increases in the year immediately following treatment. Water and sediment yield changes do not follow the same post-treatment patterns. Water yields increased immediately following treatment and, over time, gradually dropped towards pre-harvest levels. Annual sediment yields increased in some years after the harvest, but in some cases the increase was years after treatment. Monthly sediment yields increased in the first year following the clearcut harvest, but elevated monthly loads following the partial cut harvest came years later. Hence, we investigate the changes in sediment yield through an examination of water yield and sediment concentration and in response to events. We test the sensitivity of our results to different methods for computing sediment yields based on total suspended solids concentration and continuous discharge measurements. Flow-weighted sediment yield averaged 24% higher than sediment yield computed from linear-interpolated total suspended solids concentration values. During typical summer and fall conditions, flow-weighting was found to overweight storm measurements and produce large sediment yield estimates. Further work is suggested to test methods of calculating monthly sediment yields with irregularly

  7. Effectiveness of post-fire channel treatments in reducing sediment transport

    NASA Astrophysics Data System (ADS)

    Wagenbrenner, J. W.; Robichaud, P. R.

    2010-12-01

    Wildfires can dramatically increase overland flow and thereby increase hillslope and channel erosion and sediment transport rates. Land managers often attempt to mitigate these effects by applying channel treatments, but questions about the effectiveness of post-fire channel treatments in reducing erosion and sediment transport rates in headwater streams remain largely unanswered. Further, the effects of these treatments on channel processes are not well-documented. We modeled a post-fire channel using a laboratory flume to determine if straw bale check dams reduce the sediment delivery rate or affect channel incision rates. The model was based on field measurements of post-wildfire peak flow rates and sediment concentrations from an instrumented watershed in Colorado. Sediment for the experiment was collected from a post-wildfire debris flood in central Idaho. The flume had a slope of 8.5%, a width of 0.4 m, and a length of 11.4 m. Five runoff events with flow rates between 0.0108 and 0.0120 m3 s-1, sediment addition rates between 0.5 and 2.4 kg s-1, and flow durations between 15 and 20 min were conducted in the untreated flume model. The channel was rebuilt with the addition of straw bale check dams before the same five events were repeated. Bed load sediment delivery rates were measured continuously during each runoff event. Channel topography was measured before and after each event using a laser elevation profiler. Initial results indicate that sediment production rates for the 5 untreated events produced 1030 kg of sediment while the treated channel produced 930 kg of sediment. Channel incision also was less in the treated channel. These results will help land managers assess the potential benefits of using straw bale check dams as a post-fire channel treatment.

  8. Concentration of Antifouling Biocides and Metals in Sediment Core Samples in the Northern Part of Hiroshima Bay

    PubMed Central

    Tsunemasa, Noritaka; Yamazaki, Hideo

    2014-01-01

    Accumulation of Ot alternative antifoulants in sediment is the focus of this research. Much research had been done on surface sediment, but in this report, the accumulation in the sediment core was studied. The Ot alternative antifoulants, Diuron, Sea-Nine211, and Irgarol 1051, and the latter’s degradation product, M1, were investigated in five samples from the northern part of Hiroshima Bay. Ot compounds (tributyltin (TBT) and triphenyltin (TPT)) were also investigated for comparison. In addition, metal (Pb, Cu, Zn, Fe and Mn) levels and chronology were measured to better understand what happens after accumulation on the sea floor. It was discovered that Ot alternative antifoulant accumulation characteristics in sediment were like Ot compounds, with the concentration in the sediment core being much higher than surface sediment. The concentration in sediment seems to have been affected by the regulation of Ot compounds in 1990, due to the concentration of Ot alternative antifoulants and Ot compounds at the survey point in front of the dock, showing an increase from almost the same layer after the regulation. PMID:24901529

  9. In-Stream Sediment Dynamics for predicted environmental concentration calculations of plant protection products in the FOCUSSW Scenarios

    NASA Astrophysics Data System (ADS)

    Strehmel, Alexander; Erzgräber, Beate; Gottesbüren, Bernhard

    2016-04-01

    The exposure assessment for the EU registration procedure of plant protection products (PPP), which is based on the 'Forum for the co-ordination of pesticide fate models and their use' (FOCUS), currently considers only periods of 12-16 months for the exposure assessment in surface water bodies. However, in a recent scientific opinion of the European Food Safety Authority (EFSA) it is argued that in a multi-year exposure assessment, the accumulation of PPP substances in river sediment may be a relevant process. Therefore, the EFSA proposed to introduce a sediment accumulation factor in order to account for enrichment of PPP substances over several years in the sediment. The calculation of this accumulation factor, however, would consider degradation in sediment as the only dissipation path, and does not take into account riverine sediment dynamics. In order to assess the influence of deposition and the possible extent of substance accumulation in the sediment phase, the hydraulic model HEC-RAS was employed for an assessment of in-stream sediment dynamics of the FOCUS stream scenarios. The model was parameterized according to the stream characteristics of the FOCUS scenarios and was run over a period of 20 years. The results show that with the distribution of grain sizes and the ranges of flow velocity in the FOCUS streams the main sediment process in the streams is transport. First modeling results suggest that about 80% of the eroded sediment mass from the adjacent field are transported to the downstream end of the stream and out of the system, while only about 20% are deposited in the river bed. At the same time, only about 30% of in-stream sediment mass stems from the adjacent field and is associated with PPP substance, while the remaining sediment consists of the substance-free base sediment concentration regarded in the scenarios. With this, the hydraulic modelling approach is able to support the development of a meaningful sediment accumulation factor by

  10. Remote-sensing reflectance of turbid sediment-dominated waters. Reduction of sediment type variations and changing illumination conditions effects by use of reflectance ratios.

    PubMed

    Doxaran, David; Froidefond, Jean-Marie; Castaing, Patrice

    2003-05-20

    Variations of sediment type (grain size and refractive index) and changing illumination conditions affect the reflectance signal of coastal waters and limit the accuracy of sediment-concentration estimations from remote-sensing measurements. These effects are analyzed from numerous in situ remote-sensing measurements carried out in the Gironde and Loire Estuaries and then reduced and partly eliminated when reflectance ratios between the near infrared and the visible are considered. These ratios showed high correlation with the sediment concentration. On the basis of the obtained relationships, performing correspondence functions were established that allow an accurate estimation of suspended sediments in the estuaries from Système Probatoire d'Observation de la Terre, Landsat, and Sea-Viewing Wide Field-of-View Sensor data, independently of the date of acquisition. PMID:12776997

  11. Modelling importance of sediment effects on fate and transport of enterococci in the Severn Estuary, UK.

    PubMed

    Gao, Guanghai; Falconer, Roger A; Lin, Binliang

    2013-02-15

    The paper detailed a water quality modelling study of a hyper-tidal estuary, undertaken to assess the impact of various bacteria input loads on the receiving waters in a coastal basin in the UK, by using the model developed in previous study of the same authors enterococci, used as the indicators for bathing water quality under the new European Union (EU) Bathing Water Directive, were numerically modelled using a hydro-environmental model. In particular, the numerical model used in this study includes the effects of sediment on bacteria transport processes in surface water. Finally, the importance of sediment bacteria inputs on the bathing water quality was also investigated under different weather and tidal condition. During spring tide, the bacteria input from the bed sediments are dominant for both wet and dry weather conditions. During neap tides and during dry weather conditions the inputs of bacteria from the bed sediment were still dominant, but during wet weather conditions the inputs from river were dominant. Under different tidal flow conditions some parameters had a more significant role than others. During high flow conditions the sediment re-suspensions processes were dominant, therefore the bed bacteria concentrations played a dominant role on the overall bacteria concentration levels in the water column. In contrast, during low flow conditions sediment deposition prevails and bacteria are removed from the water column. The partition coefficient was found to be more important than the bed bacteria concentrations, during low flow conditions. PMID:23290609

  12. Effects of uranium development on erosion and associated sedimentation in southern San Juan Basin, New Mexico

    USGS Publications Warehouse

    Cooley, Maurice E.

    1979-01-01

    A reconnaissance was made of some of the effects of uranium development on erosion and associated sedimentation in the southern San Juan Basin, where uranium development is concentrated. In general, the effects of exploration on erosion are minor, although erosion may be accelerated by the building of access roads, by activities at the drilling sites, and by close concentration of drilling sites. Areas where the greatest effects on erosion and sedimentation from mining and milling operations have occurred are: (1) in the immediate vicinity of mines and mills, (2) near waste piles, and (3) in stream channels where modifications, such as changes in depth have been caused by discharge of excess mine and mill water. Collapse of tailings piles could result in localized but excessive erosion and sedimentation.

  13. Regional variability in bed-sediment concentrations of wastewater compounds, hormones and PAHs for portions of coastal New York and New Jersey impacted by hurricane Sandy

    USGS Publications Warehouse

    Phillips, Patrick; Gibson, Cathy A; Fisher, Shawn C.; Fisher, Irene; Reilly, Timothy J.; Smalling, Kelly; Romanok, Kristin; Foreman, William; ReVello, Rhiannon C.; Focazio, Michael J.; Jones, Daniel K.

    2016-01-01

    Bed sediment samples from 79 coastal New York and New Jersey, USA sites were analyzed for 75 compounds including wastewater associated contaminants, PAHs, and other organic compounds to assess the post-Hurricane Sandy distribution of organic contaminants among six regions. These results provide the first assessment of wastewater compounds, hormones, and PAHs in bed sediment for this region. Concentrations of most wastewater contaminants and PAHs were highest in the most developed region (Upper Harbor/Newark Bay, UHNB) and reflected the wastewater inputs to this area. Although the lack of pre-Hurricane Sandy data for most of these compounds make it impossible to assess the effect of the storm on wastewater contaminant concentrations, PAH concentrations in the UHNB region reflect pre-Hurricane Sandy conditions in this region. Lower hormone concentrations than predicted by the total organic carbon relation occurred in UHNB samples, suggesting that hormones are being degraded in the UHNB region.

  14. Regional variability in bed-sediment concentrations of wastewater compounds, hormones and PAHs for portions of coastal New York and New Jersey impacted by hurricane Sandy.

    PubMed

    Phillips, Patrick J; Gibson, Catherine A; Fisher, Shawn C; Fisher, Irene J; Reilly, Timothy J; Smalling, Kelly L; Romanok, Kristin M; Foreman, William T; ReVello, Rhiannon C; Focazio, Michael J; Jones, Daniel K

    2016-06-30

    Bed sediment samples from 79 coastal New York and New Jersey, USA sites were analyzed for 75 compounds including wastewater associated contaminants, PAHs, and other organic compounds to assess the post-Hurricane Sandy distribution of organic contaminants among six regions. These results provide the first assessment of wastewater compounds, hormones, and PAHs in bed sediment for this region. Concentrations of most wastewater contaminants and PAHs were highest in the most developed region (Upper Harbor/Newark Bay, UHNB) and reflected the wastewater inputs to this area. Although the lack of pre-Hurricane Sandy data for most of these compounds make it impossible to assess the effect of the storm on wastewater contaminant concentrations, PAH concentrations in the UHNB region reflect pre-Hurricane Sandy conditions in this region. Lower hormone concentrations than predicted by the total organic carbon relation occurred in UHNB samples, suggesting that hormones are being degraded in the UHNB region. PMID:27177500

  15. Computing time-series suspended-sediment concentrations and loads from in-stream turbidity-sensor and streamflow data

    USGS Publications Warehouse

    Rasmussen, Patrick P.; Gray, John R.; Glysson, G. Doug; Ziegler, Andrew C.

    2010-01-01

    Over the last decade, use of a method for computing suspended-sediment concentration and loads using turbidity sensors—primarily nephelometry, but also optical backscatter—has proliferated. Because an in- itu turbidity sensor is capa le of measuring turbidity instantaneously, a turbidity time series can be recorded and related directly to time-varying suspended-sediment concentrations. Depending on the suspended-sediment characteristics of the measurement site, this method can be more reliable and, in many cases, a more accurate means for computing suspended-sediment concentrations and loads than traditional U.S. Geological Survey computational methods. Guidelines and procedures for estimating time s ries of suspended-sediment concentration and loading as a function of turbidity and streamflow data have been published in a U.S. Geological Survey Techniques and Methods Report, Book 3, Chapter C4. This paper is a summary of these guidelines and discusses some of the concepts, s atistical procedures, and techniques used to maintain a multiyear suspended sediment time series.

  16. Mercury concentrations in marine sediments near a former mercury cell chlor-alkali plant in eastern Canada.

    PubMed

    Walker, Tony R

    2016-06-15

    Concentrations of total mercury (THg) were measured in coastal marine sediments near a former chlor-alkali plant in Chaleur Bay, New Brunswick. The chlor-alkali plant has been a local point source of THg since operation began in 1963. Historical THg contamination of marine sediments and biota has been widely reported. No baseline assessment has been conducted following plant closure in 2008. Surface (0-2cm) oxidized marine sediments were sampled along a single 5.2km transect radiating from the former plant and analysed for THg. THg concentrations ranged from 0.04-0.28μgg(-1). Some localised THg concentrations exceeded Canadian marine sediment quality guidelines (n=4), but all samples (n=14) were significantly lower than previous studies conducted during plant operation. Plant closure (source control) and natural sediment recovery likely responsible for attenuating THg concentrations, but burial in deeper anoxic sediments may increase bioavilability of Hg that could pose ecological risks to marine biota. PMID:27016328

  17. Time changes in suspended sediment radiocesium concentration in rivers in Fukushima affected by the Fukushima Daiichi NPP accident

    NASA Astrophysics Data System (ADS)

    Onda, Y.

    2015-12-01

    Due to Fukushima Daiichi Nuclear Power Plant accident, radioactive materials including Cs-134 and Cs-137 were widely distributed in surrounded area. The radiocesium deposited in Fukushima area have been transported in river networks. The monitoring started at 6 sites from June 2011. Subsequently, additional 24 monitoring sites were installed between October 2012 and January 2013. Flow and turbidity (for calculation of suspended sediment concentration) were measured at each site, while suspended sediments and river water were collected every one or half month to measure Cs-134 and Cs-137 activity concentrations by gamma spectrometry. Our monitoring result data demonstrated that the Cs-137 activity concentration in sediment eroded from the runoff-erosion plot, has been almost constant for the past 3 years, however the Cs-137 concentration of suspended sediment from the forested catchment showed a slight decrease through with time. On the other hand, the suspended sediment from paddy fields and those in river water from large catchments exhibited rapid decrease in Cs-137 activity concentration with time. The decreasing trend of Cs-137 activity concentration was fitted using a two-component exponential model. Differences in the exponential reduction rates of the model were compared and discussed with respect to various land uses and catchment scales. Such analysis can provide important insights into the future prediction of radiocesium wash-off from catchments with different land uses.

  18. Insecticide concentrations in stream sediments of soy production regions of South America.

    PubMed

    Hunt, Lisa; Bonetto, Carlos; Resh, Vincent H; Buss, Daniel Forsin; Fanelli, Silvia; Marrochi, Natalia; Lydy, Michael J

    2016-03-15

    Concentrations of 17 insecticides were measured in sediments collected from 53 streams in soy production regions of South America (Argentina in 2011-2014, Paraguay and Brazil in 2013) during peak application periods. Although environmental regulations are quite different in each country, commonly used insecticides were detected at high frequencies in all regions. Maximum concentrations (and detection frequencies) for each sampling event ranged from: 1.2-7.4ng/g dw chlorpyrifos (56-100%); 0.9-8.3ng/g dw cypermethrin (20-100%); 0.42-16.6ng/g dw lambda-cyhalothrin (60-100%); and, 0.49-2.1ng/g dw endosulfan (13-100%). Other pyrethroids were detected less frequently. Banned organochlorines were most frequently detected in Brazil. In all countries, cypermethrin and/or lambda-cyhalothrin toxic units (TUs), based on Hyalella azteca LC50 bioassays, were occasionally>0.5 (indicating likely acute toxicity), while TUs for other insecticides were <0.5. All samples with total insecticide TU>1 were collected from streams with riparian buffer width<20m. A multiple regression analysis that included five landscape and habitat predictor variables for the Brazilian streams examined indicated that buffer width was the most important predictor variable in explaining total insecticide TU values. While Brazil and Paraguay require forested stream buffers, there were no such regulations in the Argentine pampas, where buffer widths were smaller. Multiple insecticides were found in almost all stream sediment samples in intensive soy production regions, with pyrethroids most often occurring at acutely toxic concentrations, and the greatest potential for insecticide toxicity occurring in streams with minimum buffer width<20m. PMID:26780136

  19. Determining modifications to bifenthrin toxicity and sediment binding affinity from varying potassium chloride concentrations in overlying water.

    PubMed

    Trimble, Andrew J; Belden, Jason B; Mueting, Sara A; Lydy, Michael J

    2010-06-01

    Bifenthrin, a current-use pyrethroid insecticide, has been repeatedly identified as a major contributor to toxicity in urban and residential stream sediment. Within an urban stream multiple stressors exist. However, other than pesticides, the influence of secondary stressors on bifenthrin toxicity has not been studied. The goal of this project was to study how dissolved ions, based on the model salt KCl, influence bifenthrin toxicity. The presence of these dissolved ions could influence bifenthrin toxicity either through joint action as a secondary toxicant or through changing the partitioning or bioavailability of bifenthrin between the sediment matrix and overlying water or pore water. The first objective was to determine if mixtures of bifenthrin and KCl, a commonly utilized reference toxicant, display additive toxicity to the benthic invertebrates Hyalella azteca and Chironomus dilutus using concentration addition and independent action mathematical models. The second objective of the present study was to examine how KCl dissolved in the overlying water influences partitioning and bioavailability of a pyrethroid (bifenthrin). Joint toxicity of bifenthrin and KCl was less than predicted by both concentration addition and independent action models. However, both models predicted the joint toxicity within a factor of two. Partitioning of bifenthrin was not significantly influenced by KCl concentrations based on K(oc) determinations and desorption to Tenax beads. This indicates that the fate and bioavailability of bifenthrin are not likely different in aquatic environments with varying dissolved ion concentrations. Therefore, the toxicological interaction that results in the antagonistic joint action between bifenthrin and KCl is likely due to the physiological effects of exposure to hypertonic solutions of KCl rather than alterations to bifenthrin bioavailability. PMID:20403629

  20. The effects of sample scheduling and sample numbers on estimates of the annual fluxes of suspended sediment in fluvial systems

    USGS Publications Warehouse

    Horowitz, Arthur J.; Clarke, Robin T.; Merten, Gustavo Henrique

    2015-01-01

    Since the 1970s, there has been both continuing and growing interest in developing accurate estimates of the annual fluvial transport (fluxes and loads) of suspended sediment and sediment-associated chemical constituents. This study provides an evaluation of the effects of manual sample numbers (from 4 to 12 year−1) and sample scheduling (random-based, calendar-based and hydrology-based) on the precision, bias and accuracy of annual suspended sediment flux estimates. The evaluation is based on data from selected US Geological Survey daily suspended sediment stations in the USA and covers basins ranging in area from just over 900 km2 to nearly 2 million km2 and annual suspended sediment fluxes ranging from about 4 Kt year−1 to about 200 Mt year−1. The results appear to indicate that there is a scale effect for random-based and calendar-based sampling schemes, with larger sample numbers required as basin size decreases. All the sampling schemes evaluated display some level of positive (overestimates) or negative (underestimates) bias. The study further indicates that hydrology-based sampling schemes are likely to generate the most accurate annual suspended sediment flux estimates with the fewest number of samples, regardless of basin size. This type of scheme seems most appropriate when the determination of suspended sediment concentrations, sediment-associated chemical concentrations, annual suspended sediment and annual suspended sediment-associated chemical fluxes only represent a few of the parameters of interest in multidisciplinary, multiparameter monitoring programmes. The results are just as applicable to the calibration of autosamplers/suspended sediment surrogates currently used to measure/estimate suspended sediment concentrations and ultimately, annual suspended sediment fluxes, because manual samples are required to adjust the sample data/measurements generated by these techniques so that they provide depth-integrated and cross

  1. Central Colorado Assessment Project (CCAP)-Geochemical data for rock, sediment, soil, and concentrate sample media

    USGS Publications Warehouse

    Granitto, Matthew; DeWitt, Ed H.; Klein, Terry L.

    2010-01-01

    This database was initiated, designed, and populated to collect and integrate geochemical data from central Colorado in order to facilitate geologic mapping, petrologic studies, mineral resource assessment, definition of geochemical baseline values and statistics, environmental impact assessment, and medical geology. The Microsoft Access database serves as a geochemical data warehouse in support of the Central Colorado Assessment Project (CCAP) and contains data tables describing historical and new quantitative and qualitative geochemical analyses determined by 70 analytical laboratory and field methods for 47,478 rock, sediment, soil, and heavy-mineral concentrate samples. Most samples were collected by U.S. Geological Survey (USGS) personnel and analyzed either in the analytical laboratories of the USGS or by contract with commercial analytical laboratories. These data represent analyses of samples collected as part of various USGS programs and projects. In addition, geochemical data from 7,470 sediment and soil samples collected and analyzed under the Atomic Energy Commission National Uranium Resource Evaluation (NURE) Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) program (henceforth called NURE) have been included in this database. In addition to data from 2,377 samples collected and analyzed under CCAP, this dataset includes archived geochemical data originally entered into the in-house Rock Analysis Storage System (RASS) database (used by the USGS from the mid-1960s through the late 1980s) and the in-house PLUTO database (used by the USGS from the mid-1970s through the mid-1990s). All of these data are maintained in the Oracle-based National Geochemical Database (NGDB). Retrievals from the NGDB and from the NURE database were used to generate most of this dataset. In addition, USGS data that have been excluded previously from the NGDB because the data predate earliest USGS geochemical databases, or were once excluded for programmatic reasons

  2. Elucidating Geochemical Controls on the Concentration and Composition of Organic Carbon in Deep Pelagic Sediments

    NASA Astrophysics Data System (ADS)

    Estes, E. R.; Hansel, C. M.; Anderson, C. H.; Murray, R. W.; Dyar, M. D.; Nordlund, D.; Wankel, S. D.; Johnson, D.; Spivack, A. J.; Sauvage, J.; McKinley, C. C.; Homola, K.; Present, T. M.; Pockalny, R. A.; D'Hondt, S.

    2015-12-01

    In marine sediments, total organic carbon (OC) content correlates strongly with mineral surface area as well as the abundance of specific mineral classes such as clays and metal oxides. Adsorption to mineral surfaces and the formation of mineral-organic matter aggregates are thought to provide protection against remineralization, yet the extent and mechanism(s) of this protection are unknown. Accordingly, the goal of this research is to elucidate the role of minerals in preserving carbon and the potential for this reservoir of mineral-hosted carbon to support heterotrophic metabolisms in the otherwise carbon-poor subseafloor. Here, we characterize the composition of OC in oxic and suboxic sediments collected during R/V Knorr expedition 223 to the subtropical western North Atlantic in November 2014. We find that OC concentrations decrease linearly over ~25 meters burial depth, from ~0.15 to 0.075 mol OC/kg solid. Organic C/N varies but is consistently less than Redfield values of ~6. Relative contributions of functional groups quantified using bulk-scale Fourier transform infrared (FTIR) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy change with depth and site lithology/geochemistry. We further observe microscale heterogeneity, including discrete carbonate particles amid disperse aromatic and amide/carboxylic-rich organic carbon, using scanning transmission X-ray microscopy (STXM) coupled to NEXAFS. In the suboxic sediments, there is a transition from Mn(III/IV) phases toward more reduced phases shown by X-ray absorption spectroscopy between ~3-11 meters below core top, approximately between the interstitial water nitrate and nitrite maxima. Conversely, Fe(III)-bearing minerals are present throughout the core and may contribute to stabilization of OC. By further coupling micro- and macro-scale analysis, the role of minerals in OC sequestration in the marine subsurface will come to light.

  3. Effect of membrane filtration artifacts on dissolved trace element concentrations

    USGS Publications Warehouse

    Horowitz, Arthur J.; Elrick, Kent A.; Colberg, Mark R.

    1992-01-01

    Among environment scientists, the current and almost universally accepted definition of dissolved constituents is an operational one; only those materials which pass through a 0.45-??m membrane filter are considered to be dissolved. Detailed laboratory and field studies on Fe and Al indicate that a number of factors associated with filtration, other than just pore size, can substantially alter 'dissolved' trace element concentrations; these include: filter type, filter diameter, filtration method, volume of sample processed, suspended sediment concentration, suspended sediment grain-size distribution, concentration of colloids and colloidally associated trace elements and concentration of organic matter. As such, reported filtered-water concentrations employing the same pore size filter may not be equal. Filtration artifacts may lead to the production of chemical data that indicate seasonal or annual 'dissolved' chemical trends which do not reflect actual environmental conditions. Further, the development of worldwide averages for various dissolved chemical constituents, the quantification of geochemical cycles, and the determination of short- or long-term environmental chemical trends may be subject to substantial errors, due to filtration artifacts, when data from the same or multiple sources are combined. Finally, filtration effects could have a substantial impact on various regulatory requirements.

  4. Effects of cadmium-spiked sediment on cadmium accumulation and bioturbation by nymphs of the burrowing mayfly Hexagenia bilineata

    USGS Publications Warehouse

    Bartsch, M.R.; Cope, W.G.; Rada, R.G.

    1999-01-01

    We assessed accumulation of cadmium (Cd) and bioturbation by nymphs of the burrowing mayfly Hexagenia bilineata as indicators of exposure to Cd- spiked sediment in a 21-d test. Surficial sediments (top 5 cm) from Pool 7 of the Upper Mississippi River were spiked with Cd to concentrations of 3, 7, and 15 ??g Cd g-1 dry weight. The experimental design was completely randomized, with three Cd-spiked sediment treatments plus an unspiked sediment control (1 ??g Cd g-1 dry weight), and 10 nymphs in each of six replicates per treatment. Nymphs accumulated Cd during the 21-d exposure; mean concentrations varied from 0.22 to 6.24 ??g g-1 dry weight, and tissue concentrations were correlated with Cd concentration in unfiltered test water (r = 0.93, P < 0.01) and test sediment (r = 0.93, P < 0.01). The effect of Cd on bioturbation by nymphs, as indicated by turbidity, differed significantly among treatments (P = 0.045) and over time within treatments (P = 0.01). Turbidity progressively decreased as Cd concentration in the sediment increased, up to 7 ??g g-1; however, turbidity in the 15 ??g g-1 treatment (our greatest exposure concentration) did not differ significantly from the control. Concentrations of Cd in unfiltered, overlying test water increased significantly within treatments during the test, indicating that nymphs mobilized sediment-associated Cd into the overlying water, presumably through burrowing and respiratory activities.

  5. Evaluation of data driven models for river suspended sediment concentration modeling

    NASA Astrophysics Data System (ADS)

    Zounemat-Kermani, Mohammad; Kişi, Özgür; Adamowski, Jan; Ramezani-Charmahineh, Abdollah

    2016-04-01

    Using eight-year data series from hydrometric stations located in Arkansas, Delaware and Idaho (USA), the ability of artificial neural network (ANN) and support vector regression (SVR) models to forecast/estimate daily suspended sediment concentrations ([SS]d) was evaluated and compared to that of traditional multiple linear regression (MLR) and sediment rating curve (SRC) models. Three different ANN model algorithms were tested [gradient descent, conjugate gradient and Broyden-Fletcher-Goldfarb-Shanno (BFGS)], along with four different SVR model kernels [linear, polynomial, sigmoid and Radial Basis Function (RBF)]. The reliability of the applied models was evaluated based on the statistical performance criteria of root mean square error (RMSE), Pearson's correlation coefficient (PCC) and Nash-Sutcliffe model efficiency coefficient (NSE). Based on RMSE values, and averaged across the three hydrometric stations, the ANN and SVR models showed, respectively, 23% and 18% improvements in forecasting and 18% and 15% improvements in estimation over traditional models. The use of the BFGS training algorithm for ANN, and the RBF kernel function for SVR models are recommended as useful options for simulating hydrological phenomena.

  6. Estimation of suspended sediment concentrations using Terra MODIS: an example from the Lower Yangtze River, China.

    PubMed

    Wang, J-J; Lu, X X

    2010-02-01

    Traditional measurements of suspended sediment concentrations (SSC) through in-situ sampling in rivers are expensive and time-consuming to perform. Thus, these methods cannot provide continuous SSC records. Although remote sensing has been used for SSC estimation, little research has been undertaken on inland rivers, especially for highly turbid rivers like the Yangtze. Previous studies have proposed Landsat TM/ETM+ Band 4 as a spectral SSC indicator for the Yangtze, but its limitation on temporal resolution is insufficient for the study of dynamic changes of sediment. This paper presents a method of estimating SSC of the Yangtze at Jiujiang using time-series satellite data of high temporal resolution Terra MODIS. It was found that differences in water reflectance between Band 2 and Band 5 could provide relatively accurate SSC estimation even when in-situ atmospheric conditions were unknown. After cross-validation, mean absolute relative error (ARE) and relative root mean square error (RRMSE) were relatively low (i.e., 25.5% and 36.5%, respectively). This empirical relationship was successfully applied to the estimation of SSC at Datong in the Lower Yangtze River, although the SSC values were generally underestimated. This study suggests that Terra MODIS could be used to estimate SSC in large turbid rivers, although some influencing factors require further study to improve the accuracy of SSC estimation. PMID:20022078

  7. Uranium hydrogeochemical and stream sediment reconnaissance of the Newcastle NTMS Quadrangle, Wyoming, including concentrations of forty-two additional elements

    SciTech Connect

    Goff, S.J.; Sandoval, W.F.; Gallimore, D.L.; Talcott, C.L.; Martinez, R.G.; Minor, M.E.; Mills, C.F.

    1980-06-01

    Water and sediment samples were collected and each water sample was analyzed for U, and each sediment sample was analyzed for 43 elements, including U and Th. Uranium concentrations in water samples range from below the detection limit of 0.02 ppB to 702.26 ppB and have a median of 1.73 ppB and a mean of 11.76 ppB. Water samples containing high uranium concentrations generally are associated with known uranium mining activity or units known to be uranium bearing. About one-third of the water samples containing high uranium concentrations were collected from locations within the Pumpkin Buttes and Turnercrest-Ross Districts. Nearly half of the water samples containing high uranium concentrations were collected from locations just west of the Monument Hill and Highland Flats-Box Creek Districts. Similar anomalous uranium concentrations in this region have been reported updip from Exxon's Highland uranium deposits. High uranium concentrations were also found associated with the Lance Creek-Old Woman Anticline District. Uranium concentrations in sediment samples range from 1.14 to 220.70 ppM and have a median of 3.37 ppM and a mean of 4.03 ppM. Throughout the major uranium mining districts of the Powder River Basin, sediment samples with high uranium concentrations were collected from dry streams located near wells producing water samples with high uranium concentrations. High uranium concentrations were also found associated with the Lance Creek oil field where uranium mineralization is known in the White River formation. High uranium concentrations were also found in sediment samples in areas where uranium mineralization is not known. These samples are from dry streams in areas underlain by the White River formation, the Niobrara formation, and the Pierre, Carlisle, Belle Fourche, and Mowry shales.

  8. Assessments of radioactivity concentration of natural radionuclides and radiological hazard indices in sediment samples from the East coast of Tamilnadu, India with statistical approach.

    PubMed

    Ravisankar, R; Chandramohan, J; Chandrasekaran, A; Prince Prakash Jebakumar, J; Vijayalakshmi, I; Vijayagopal, P; Venkatraman, B

    2015-08-15

    This paper reports on the distribution of three natural radionuclides (238)U, (232)Th and (40)K in coastal sediments from Pattipulam to Devanampattinam along the East coast of Tamilnadu to establish baseline data for future environmental monitoring. Sediment samples were collected by a Peterson grab samples from 10m water depth parallel to the shore line. Concentration of natural radionuclides were determined using a NaI(Tl) detector based γ-spectrometry. The mean activity concentration is ⩽2.21, 14.29 and 360.23Bqkg(-1) for (238)U, (232)Th and (40)K, respectively. The average activity of (232)Th, (238)U and (40)K is lower when compared to the world average value. Radiological hazard parameters were estimated based on the activity concentrations of (238)U, (232)Th and (40)K to find out any radiation hazard associated with the sediments. The radiological hazard parameters such as radium equivalent activity (Raeq), absorbed gamma dose rates in air (DR), the annual gonadal dose equivalent (AGDE), annual effective dose equivalent (AEDE), external hazard index (Hex) internal hazard index (Hin), activity utilization index (AUI) and excess lifetime cancer (ELCR) associated with the radionuclides were calculated and compared with internationally approved values and the recommended safety limits. Pearson correlation, principal component analysis (PCA) and hierarchical cluster analysis (HCA) have been applied in order to recognize and classify radiological parameters in sediments collected at 22 sites on East coast of Tamilnadu. The values of radiation hazard parameters were comparable to the world averages and below the recommended values. Therefore, coastal sediments do not to pose any significant radiological health risk to the people living in nearby areas along East coast of Tamilnadu. The data obtained in this study will serve as a baseline data in natural radionuclide concentration in sediments along the coastal East coast of Tamilnadu. PMID:26036177

  9. Effects of sulfate-reducing bacteria on methylmercury at the sediment-water interface.

    PubMed

    Zeng, Lingxia; Luo, Guangjun; He, Tianrong; Guo, Yanna; Qian, Xiaoli

    2016-08-01

    Sediment cores (containing sediment and overlying water) from Baihua Reservoir (SW China) were cultured under different redox conditions with different microbial activities, to understand the effects of sulfate-reducing bacteria (SRB) on mercury (Hg) methylation at sediment-water interfaces. Concentrations of dissolved methyl mercury (DMeHg) in the overlying water of the control cores with bioactivity maintained (BAC) and cores with only sulfate-reducing bacteria inhibited (SRBI) and bacteria fully inhibited (BACI) were measured at the anaerobic stage followed by the aerobic stage. For the BAC and SRBI cores, DMeHg concentrations in waters were much higher at the anaerobic stage than those at the aerobic stage, and they were negatively correlated to the dissolved oxygen concentrations (r=-0.5311 and r=-0.4977 for BAC and SRBI, respectively). The water DMeHg concentrations of the SRBI cores were 50% lower than those of the BAC cores, indicating that the SRB is of great importance in Hg methylation in sediment-water systems, but there should be other microbes such as iron-reducing bacteria and those containing specific gene cluster (hgcAB), besides SRB, causing Hg methylation in the sediment-water system. PMID:27521953

  10. Effects of ammonia on juvenile unionid mussels (Lampsilis cardium) in laboratory sediment toxicity tests

    USGS Publications Warehouse

    Newton, Teresa J.; Allran, John W.; O'Donnell, Jonathan A.; Bartsch, Michelle; Richardson, William B.

    2003-01-01

    Ammonia is a relatively toxic compound generated in water and sediments by heterotrophic bacteria and accumulates in sediments and pore water. Recent data suggest that unionid mussels are sensitive to un-ionized ammonia (NH3) relative to other organisms. Existing sediment exposure systems are not suitable for ammonia toxicity studies with juvenile unionids; thus, we modified a system to expose juveniles to ammonia that was continuously infused into sediments. This system maintained consistent concentrations of ammonia in pore water up to 10 d. Juvenile Lampsilis cardium mussels were exposed to NH3 in pore water in replicate 96-h and 10-d sediment toxicity tests. The 96-h median lethal concentrations (LC50s) were 127 and 165 μg NH3-N/L, and the 10-d LC50s were 93 and 140 μg NH3-N/L. The median effective concentrations (EC50s) (based on the proportion affected, including dead and inactive mussels) were 73 and 119 μg NH3-N/L in the 96-h tests and 71 and 99 μg NH3-N/L in the 10-d tests. Growth rate was substantially reduced at concentrations between 31 and 76 μg NH3-N/L. The lethality results (when expressed as total ammonia) are about one-half the acute national water quality criteria for total ammonia, suggesting that existing criteria may not protect juvenile unionids.

  11. Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: Procedures for the Determination of the Freely Dissolved Interstitial Water Concentrations of Nonionic Organics

    EPA Science Inventory

    This document describes procedures to determine the concentrations of nonionic organic chemicals in sediment interstitial waters. In previous ESB documents, the general equilibrium partitioning (EqP) approach was chosen for the derivation of sediment benchmarks because it account...

  12. Effect of root exudates on sorption, desorption, and transport of phenanthrene in mangrove sediments.

    PubMed

    Jia, Hui; Lu, Haoliang; Dai, Minyue; Hong, Hualong; Liu, Jingchun; Yan, Chongling

    2016-08-15

    The effect of root exudates on the environmental behaviors of phenanthrene in mangrove sediments is poorly understood. In order to evaluate their influence, comprehensive laboratory experiments were performed using batch equilibrium and thin-layer chromatography (TLC) analyses. In the presence of root exudates, sorption of phenanthrene was inhibited, whereas desorption and mobility were promoted, and were elevated as root exudate concentrations increased. Among the three representative low molecular weight organic acids (LMWOAs) (citric, oxalic, and acetic acids), citric acid promoted desorption and mobility of phenanthrene more effectively than the other two. In addition, application of artificial root exudates (AREs) enhanced phenanthrene desorption, and mobility was always lower than that with the same concentration of LMWOAs, suggesting that LMWOAs predominantly affected the fate of phenanthrene in sediments. The results of this study could enhance our understanding of the mobility of persistent organic pollutants in sediment-water system. PMID:27293074

  13. Ecological effects of contaminated sediments following a decade of no industrial effluents emissions: the Sediment Quality Triad approach.

    PubMed

    Lopes, Marta Lobão; Rodrigues, Ana Maria; Quintino, Victor

    2014-10-15

    Sediments contaminated by industrial effluents a decade after the emissions were stopped were statistically compared to sediments from reference channels, using the Sediment Quality Triad approach. The metals and metalloid concentrations, mainly Hg and As, increased towards the upper part of a contaminated channel, where the industrial discharge was located. A bioaccumulation assay with Scrobicularia plana showed the highest bioaccumulation and mortality in the most contaminated sediments and bioaccumulation strongly correlated with the sediments metals and metalloid concentrations. The resident macroinvertebrate community also showed significant differences between the contaminated and reference channels, in the upper areas, where the community was most affected. All three elements of the quality triad rejected the null hypothesis and indicated that despite the emissions ceasing in 2004, sediments remain contaminated by high levels of metals and metalloid, leading to bioaccumulation and with severe community level consequences. PMID:25152187

  14. Heavy metal concentrations and enzymatic activities in the functional zone sediments of Haizhou Bay, Lianyungang, Jiangsu, China.

    PubMed

    Li, Yu; Liu, Fu-cheng

    2015-11-01

    Surface sediments were collected at 31 sites covering five functional zones of Haizhou Bay, Lianyungang, Jiangsu, China. Heavy metal concentrations and enzymatic activity of phosphatase and urease were determined on a dry-weight basis of sediments. Metal concentrations in sediments were comparable to the Chinese National Standard of Marine Sediment Quality and were as follows: Cu, 8.60-55.8 mg kg(-1); Zn, 107-384 mg kg(-1); Pb, 33.6-200 mg kg(-1); Cd, 0.24-2.57 mg kg(-1); Cr, 30.3-92.1 mg kg(-1); As, 12.9-110 mg kg(-1); Ni, 15.8-49.6 mg kg(-1); Mn, 379-1272 mg kg(-1); and Fe, 13,790-38,240 mg kg(-1). A geoaccumulation index (I geo) was calculated to help researchers understand the status of pollutants in the sediments. I geo showed that Cd and As contamination existed in the study area. The mobility of the metals and the relationship between heavy metal concentrations of chemical fractions and enzymatic activities were also investigated. Results showed that Cd and Mn had higher mobility than other metals, and enzymatic activities may play an important role in controlling the bioavailability and transformation trend of heavy metals from one fraction to another in sediments. PMID:26431704

  15. Effects of Deepwater Algae on C-N-P Cycling in Permeable Sediments

    NASA Astrophysics Data System (ADS)

    Sansone, F. J.; Spalding, H. L.; Smith, C. M.

    2007-12-01

    Extensive deepwater (50-100 m depth) meadows of native and introduced macroalgae occur offshore of the main Hawaiian Islands. Sediment porewater (to 25 cm sediment depth) and overlying seawater were collected during September and December 2004, and November and December 2006 from 13 vegetated and non-vegetated deepwater sites on sand and muddy-sand seafloors offshore from Oahu to Kaho'olawe. Porewater dissolved nutrient concentrations were comparable to those in nearshore permeable (sandy) sediments, with highly elevated concentrations at sediment depths available to algal holdfasts. Maximum observed concentrations were: 2.3 uM phosphate, 30 uM nitrate, 0.65 uM nitrite, 105 uM ammonium, and 88 uM silica. The sediment organic matter content was not correlated with the presence or absence of macroalgae. Vegetated sediments were consistently more oxidizing than non-vegetated sediments, judged from (nitrate + nitrite)/ammonium ratios. Halimeda-vegetated sediments had low DIN levels compared to other sites, suggesting algal uptake. These sands also exhibited dissolved inorganic carbon depletion at depth, perhaps also related to algal metabolism. In contrast, Udotea-vegetated sediments had high levels of DIN, indicating little or no algal DIN uptake and/or the presence of active N-fixation; these sands also had no DIC depletion at depth. Udotea-vegetated sediments also appeared highly oxidizing, evidenced by very high levels of dissolved nitrate and nitrite, along with low levels of ammonium. The calculated tracer N* was used to verify the conclusions regarding net DIN uptake; a similar calculated tracer, computed using Redfield-type N:Si ratios, was used to confirm the N* results. Unvegetated, nutrient- and organic-rich sandy mud along the flanks of Haleakala volcano showed near complete dissolved phosphate removal, perhaps due to adsorption onto freshly weathered iron oxy-hydroxides. Such phosphate removal was not seen at other sites, including a nearby non

  16. Metal concentrations in surface water and sediments from Pardo River, Brazil: human health risks.

    PubMed

    Alves, Renato I S; Sampaio, Carolina F; Nadal, Martí; Schuhmacher, Marta; Domingo, José L; Segura-Muñoz, Susana I

    2014-08-01

    Pardo River (Brazil) is suffering from an important anthropogenic impact due to the pressure of highly populated areas and the influence of sugarcane cultivation. The objective of the present study was to determine the levels of 13 trace elements (As, Be, Cd, Cr, Cu, Pb, Mn, Hg, Ni, Tl, Sn, V and Zn) in samples of surface water and sediments from the Pardo River. Furthermore, the human health risks associated with exposure to those metals through oral intake and dermal absorption were also evaluated. Spatial and seasonal trends of the data were closely analyzed from a probabilistic approach. Manganese showed the highest mean concentrations in both water and sediments, remarking the incidence of the agricultural activity and the geological characteristics within the basin. Thallium and arsenic were identified as two priority pollutants, being the most important contributors to the Hazard Index (HI). Since non-carcinogenic risks due to thallium exposure slightly exceeded international guidelines (HI>1), a special effort should be made on this trace element. However, the current concentrations of arsenic, a carcinogenic element, were in accordance to acceptable lifetime risks. Nowadays, there is a clear increasing growth in human population and economic activities in the Pardo River, whose waters have become a serious strategic alternative for the potential supply of drinking water. Therefore, environmental monitoring studies are required not only to assure that the current state of pollution of Pardo River does not mean a risk for the riverside population, but also to assess the potential trends in the environmental levels of those elements. PMID:24949813

  17. Effects of physical and chemical characteristics of surface sediments in the formation of shallow lake algae-induced black bloom.

    PubMed

    Shen, Qiushi; Liu, Cheng; Zhou, Qilin; Shang, Jingge; Zhang, Lei; Fan, ChengXin

    2013-12-01

    Surface sediments are closely related to lake black blooms. The dissolved oxygen (DO) distribution and its penetration depth in surface sediments as well as the migration and transformation of redox sensitive elements such as Fe and S at the sediment-water interface are important factors that could influence the formation of the black bloom. In this study, dredged and undredged sediment cores with different surface properties were used to simulate black blooms in the laboratory. The Micro Profiling System was employed to explore features of the DO and sigmaH2S distribution at the sediment-water interface. Physical and chemical characteristics in sediments and pore waters were also analyzed. The results showed that sediment dredging effectively suppressed the black blooms. In the undredged treatment, DO penetration depth was only 50 microm. Fe(2+) concentrations, sigmaH2S concentrations, and sigmaH2S production rates were remarkably higher in surface sediments and pore waters compared to control and dredged treatments. Furthermore, depletion of DO and accumulation of Fe(2+) and sigmaH2S in surface sediments and pore waters provided favorable redox environments and necessary material sources for the blooms. The study results proved that physical and chemical characteristics in surface sediments are important factors in the formation of the black bloom, and could provide scientific guidance for emergency treatment and long-term pre-control of black blooms. PMID:24649664

  18. Spatial characterization of riparian buffer effects on sediment loads from watershed systems.

    PubMed

    Momm, Henrique G; Bingner, Ronald L; Yuan, Yongping; Locke, Martin A; Wells, Robert R

    2014-09-01

    Understanding all watershed systems and their interactions is a complex, but critical, undertaking when developing practices designed to reduce topsoil loss and chemical/nutrient transport from agricultural fields. The presence of riparian buffer vegetation in agricultural landscapes can modify the characteristics of overland flow, promoting sediment deposition and nutrient filtering. Watershed simulation tools, such as the USDA-Annualized Agricultural Non-Point Source (AnnAGNPS) pollution model, typically require detailed information for each riparian buffer zone throughout the watershed describing the location, width, vegetation type, topography, and possible presence of concentrated flow paths through the riparian buffer zone. Research was conducted to develop GIS-based technology designed to spatially characterize riparian buffers and to estimate buffer efficiency in reducing sediment loads in a semiautomated fashion at watershed scale. The methodology combines modeling technology at different scales, at individual concentrated flow paths passing through the riparian zone, and at watershed scales. At the concentrated flow path scale, vegetative filter strip models are applied to estimate the sediment-trapping efficiency for each individual flow path, which are aggregated based on the watershed subdivision and used in the determination of the overall impact of the riparian vegetation at the watershed scale. This GIS-based technology is combined with AnnAGNPS to demonstrate the effect of riparian vegetation on sediment loadings from sheet and rill and ephemeral gully sources. The effects of variability in basic input parameters used to characterize riparian buffers, onto generated outputs at field scale (sediment trapping efficiency) and at watershed scale (sediment loadings from different sources) were evaluated and quantified. The AnnAGNPS riparian buffer component represents an important step in understanding and accounting for the effect of riparian

  19. Concentration of trace metals in sediments and soils from protected lands in south Florida: background levels and risk evaluation.

    PubMed

    Castro, Joffre E; Fernandez, Adolfo M; Gonzalez-Caccia, Valentina; Gardinali, Piero R

    2013-08-01

    A comprehensive environmental evaluation was completed on 20 metals: two reference metals (Fe, Al) and several minor trace metals (As, Ba, Co, Cr, Cu, Mn, Ni, Pb, V, and Zn) for surface soils and sediments collected from 50 sites in Everglades National Park (ENP), the coastal fringes of Biscayne National Park (BNP), and Big Cypress National Preserve. Samples were prepared by acid digestion (EPA3050) and analyzed by ICP/MS detection (EPA6020). Although no widespread contamination was detected across the two parks and one preserve, there were some specific areas where metal concentrations exceeded Florida's ecological thresholds, suggesting that some metals were of concern. A screening-level evaluation based on a proposed effect index grouped trace metals by their potential for causing negligible, possible, and probable effects on the biota. For example, Cu in BNP and Cr and Pb in ENP were considered of concern because their adverse effect likelihood to biota was assessed as probable; consequently, these trace metals were selected for further risk characterization. Also, stations were ranked based on a proposed overall contamination index that showed that: site BB10 in BNP and sites E3 and E5 in ENP had the highest scores. The first site was located in a marina in BNP, and the other two sites were along the eastern boundary of ENP adjacent to current or former agricultural lands. An assessment tool for south Florida protected lands was developed for evaluating impacts from on-going Everglades restoration projects and to assist State and Federal agencies with resource management. The tool consists of enrichment plots and statistically derived background concentrations based on soil/sediment data collected from the two national parks and one preserve. Finally, an equally accurate but much simplified approach is offered for developing enrichment plots for other environmental settings. PMID:23288595

  20. Effects of acid-volatile sulfide on zinc bioavailability and toxicity to benthic macroinvertebrates: A spiked sediment field experiment

    SciTech Connect

    Liber, K.; Call, D.J.; Markee, T.P.; Schmude, K.L.; Balcer, M.D.; Whiteman, F.W.; Ankley, G.T.

    1996-12-01

    Acid-volatile sulfide (AVS) has been proposed as the primary normalization phase for the development of sediment quality criteria for certain cationic metals. This study was designed to assist in this development by providing necessary field data on the relationships among season, AVS concentrations, and zinc bioavailability and toxicity in freshwater sediments. Zinc was spiked into uncontaminated sediments collected from a local pond, creating five simultaneously extracted metal (SEM) concentrations ranging from 0.8 to 12.0 {micro}mol/g dry weight. The spiked sediments were transferred to 4-L plastic trays, returned to the bottom of the pond, and sampled on five dates during 1993--1994. Results revealed a pronounced increase in AVS concentration with increasing zinc concentration. Acid-volatile sulfide concentrations in zinc-spiked sediments displayed only minor seasonal variation but were lowest in surficial (0--2 cm) sediments. Acid-volatile sulfide concentrations always exceeded SEM concentrations at {le}6.0 {micro}mol SEM/g; only at 12.0 {micro}mol SEM/g did SEM/AVS ratios exceed 1.0. Zinc was rarely detected in pore water at any treatment and never at concentrations which should have posed a hazard to benthic macroinvertebrates. No substantial effect on colonization of zinc-spiked sediments by benthic macroinvertebrates was observed. Only oligochaetes (Naididae) were significantly reduced in abundance at the high zinc treatment, although reductions were occasionally evident for other taxa. Lack of noteworthy pore-water zinc concentrations and lack of associated, ecologically meaningful effects were attributed to the increase in AVS levels observed with increasing SEM zinc sediment concentration. The increases in AVS theoretically resulted from a replacement of natural iron and manganese sulfides with the more stable zinc sulfide complex.

  1. Total and methyl mercury concentrations in sediment and water of a constructed wetland in the Athabasca Oil Sands Region.

    PubMed

    Oswald, Claire J; Carey, Sean K

    2016-06-01

    In the Athabasca Oil Sands Region in northeastern Alberta, Canada, oil sands operators are testing the feasibility of peatland construction on the post-mining landscape. In 2009, Syncrude Canada Ltd. began construction of the 52 ha Sandhill Fen pilot watershed, including a 15 ha, hydrologically managed fen peatland built on sand-capped soft oil sands tailings. An integral component of fen reclamation is post-construction monitoring of water quality, including salinity, fluvial carbon, and priority pollutant elements. In this study, the effects of fen reclamation and elevated sulfate levels on mercury (Hg) fate and transport in the constructed system were assessed. Total mercury (THg) and methylmercury (MeHg) concentrations in the fen sediment were lower than in two nearby natural fens, which may be due to the higher mineral content of the Sandhill Fen peat mix and/or a loss of Hg through evasion during the peat harvesting, stockpiling and placement processes. Porewater MeHg concentrations in the Sandhill Fen typically did not exceed 1.0 ng L(-1). The low MeHg concentrations may be a result of elevated porewater sulfate concentrations (mean 346 mg L(-1)) and an increase in sulphide concentrations with depth in the peat, which are known to suppress MeHg production. Total Hg and MeHg concentrations increased during a controlled mid-summer flooding event where the water table rose above the ground surface in most of the fen. The Hg dynamics during this event showed that hydrologic fluctuations in this system exacerbate the release of THg and MeHg downstream. In addition, the elevated SO4(2-) concentrations in the peat porewaters may become a problem with respect to downstream MeHg production once the fen is hydrologically connected to a larger wetland network that is currently being constructed. PMID:27017139

  2. Tracing metal sources in core sediments of the artificial lake An-Dong, Korea: Concentration and metal association.

    PubMed

    Choi, Mansik; Park, Jongkyu; Cho, Dongjin; Jang, Dongjun; Kim, Miseon; Choi, Jongwoo

    2015-09-15

    The concentration and source of trace metals in the artificial lake An-Dong, which has widespread abandoned mines and a Zn smelter upstream of the drainage basin, were investigated. Soils (18ea), stream waters (15ea) and sediments (15ea) in the main channel and five tributaries downstream of the Zn smelter towards the lake (~ 50 km downstream) were collected. And two core sediments were also taken from the middle of the lake. All samples were analyzed for trace metals in bulk and in a 1N HCl-leached fraction. Although the soil and stream sediments consisted mostly of sand-sized grains, concentrations of metals (Cu, Zn, Cd and Pb) were very high in all samples, including soils, stream waters and sediments at sites near the Zn smelter. However the metal concentrations decreased rapidly downstream, suggesting that the area of impact of the smelter lies within 5 km. Highly enriched metal concentrations were also found in dated core sediments from the lake; while the highest concentrations of Co, Ni, As, Cu, Zn, Cd and Pb were detected in the bottom of the sediment core (dated 1980) they decreased towards 2000, and only Cu, Zn and Cd concentrations increased again in present-day samples. Since the temporal variation in metal concentrations appeared consistent with historical variation in ore mining and Zn smelter production rates, a model combining the production rates of each was developed, which estimated 3%, 12% and 7% contributions from Zn smelter compared to ore mining production rate to levels of Cu, Cd and Zn, respectively, suggesting the different pathways by different sources. In addition, analysis of Cd/Zn and Cu/Zn ratios showed that contamination from ore mining decreased from 1980 to 2000, and smelting processes were most likely responsible for metal enrichment (Cu, Cd and Zn) from 2000 to the present. PMID:25981937

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

    USGS Publications Warehouse

    Madej, MaryAnn; Bundros, Greg; Klein, Randy

    2011-01-01

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

  4. Effects of titania nanoparticles on phosphorus fractions and its release in resuspended sediments under UV irradiation.

    PubMed

    Luo, Zhuanxi; Wang, Zhenhong; Li, Qingzhao; Pan, Qikun; Yan, Changzhou

    2010-02-15

    Little is known about the effects of nano-TiO(2) on the transformation and transport of phosphorus (P) in resuspended sediments. Chemical sequential extraction was used to investigate P fractions and its release in resuspended sediments under the influence of nano-TiO(2) and UV irradiation. The results showed that the contents of sediment P in all fractions decreased with increasing nano-TiO(2) concentration in UV irradiation, while increased in the dark controls. Furthermore, P release from all fractions was greater in UV irradiation than in the controls. Elevated concentrations (10-50 mg L(-1)) of nano-TiO(2) in UV irradiation significantly facilitated the release of P from organic and Fe oxide fractions, possibly resulting from the partial photo-degradation of organic matter and photochemical transformation of Fe oxides. Apparently, nano-TiO(2) in UV irradiation did not immobilize the loosely sorbed P and reductant soluble P release from the resuspended sediments, possible because (1) some of P released from those fractions were refurnished by the P released from OM; (2) photocatalysis of nano-TiO(2) reduced binding capacity of the resuspended sediments. Our results suggest that the photocatalysis of nano-TiO(2) may offer the potential to regulate the transformation and transport of sediment P in the aquatic environment. PMID:19850408

  5. Evaluation of suspended sediment concentrations in a hydropower reservoir by using a Laser In-Situ Scattering and Transmissometry instrument

    NASA Astrophysics Data System (ADS)

    Lizano, Laura; Haun, Stefan

    2014-05-01

    Sediment transported by rivers start to settle when they enter a reservoir due to reduced flow velocities and turbulences. Reservoir sedimentation is a common problem today and eliminates about 1% of the worldwide existing storage capacity annually. However, depending on the climate conditions and the geology in the catchment area this value can increase up to 5% and higher. Among the results of reservoir deposition is the loss of the storage capacity, a loss of flood control benefits or even blockage of intakes due to sediment accumulation in front of the structure. As a consequence, management tasks have to be planned and conducted to guarantee a safe and economical reservoir operation. A major part of the sediment particles entering the reservoir is transported as suspended sediment load. Hence, accurate knowledge of the transport processes of these particles in the reservoir is advantageous for planning and predicting a sustainable reservoir operation. Of special interest is the spatial distribution of the grain sizes in the reservoir, for example, which grain sizes can be expected to enter the waterway and have a major contribution in turbine abrasion. The suspended sediment concentrations and the grain size distribution along the Sandillal reservoir in Costa Rica were measured in this study by using a Laser In-Situ Scattering and Transmissometry instrument (LISST-SL). The instrument measures sediment concentrations as well as the grain size distributions instantaneously (32 grain sizes in the range between 2.1 and 350 μm) with a frequency of 0.5 Hertz. The measurements were applied at different pre-specified transects along the reservoir, in order to assess the spatial distribution of the suspended sediment concentrations. The measurements were performed in vertical lines, at different depths and for a period of 60 seconds. Additionally, the mean grain size distribution was calculated from the data for each measured point. The measurements showed that the

  6. Hydrothermal fluid effects on sediment column in Middle Valley, Juan de Fuca Ridge (northeast Pacific)

    SciTech Connect

    Al-Aasm, I.S.; Blaise, B.

    1987-05-01

    Core PAR 85-34, located near a high heat flow area in Middle Valley, northern Juan de Fuca Ridge, contains carbonate nodules of various sizes (less than or equal to 1-5 cm in length). Sedimentological, geochemical, and isotopic results allow us to understand the origin of these concretions and the effects of hydrothermal activity from nearby sulfide vents on the sediment column. The mineralogy of the olive-gray surface sediment (0-15 cm) is identical to unaffected hemipelagic sediments in the region except for a concentration of barite crystals (up to 1 cm) at the water-sediment interface. In the clay, mud fraction, and bulk sediment, the FeO, S, Ba, Cu, Ni, Pb, Zn and As are more enriched than in normal hemipelagic sediment in the area due to hydrothermal activity. Petrographic and SEM analysis of the nodules reveal iron calcite and barite minerals in cracks and on the outside part of the nodules with mineralogical and textural variations downcore. Stable isotope curves of these nodules appear to demonstrate the effects of both bacterial sulfate reduction and microbiological methane generation, with consequent extreme /sup 13/C-depletion in the precipitated carbonate. The curves also demonstrate that the hydrothermal fluid entering the system may have caused the negative shift in oxygen isotopes downcore, although this effect may have been of cyclic or episodic nature.

  7. Acetylcholinesterase in zebrafish embryos as a tool to identify neurotoxic effects in sediments.

    PubMed

    Kais, Britta; Stengel, Daniel; Batel, Annika; Braunbeck, Thomas

    2015-11-01

    In order to clarify the suitability of zebrafish (Danio rerio) embryos for the detection of neurotoxic compounds, the acetylcholinesterase assay was adapted and validated with a series of priority pollutants listed as relevant for the European water policy (Aroclor 1254, 2,3-benzofuran, bisphenol A, chlorpyrifos, paraoxon-methyl, quinoline, and methyl mercury chloride) as well as acetonic extracts from three sediments of known contamination. The acute toxicities of the model substances and the sediment extracts were determined by means of the fish embryo test as specified in OECD TG 236, and concentrations as low as the effective concentration at 10% inhibition (EC10) were used as the highest test concentration in the acetylcholinesterase test in order to avoid nonspecific systemic effects mimicking neurotoxicity. Among the model compounds, only the known acetylcholinesterase inhibitors paraoxon-methyl and chlorpyrifos produced a strong inhibition to about 20 and 33%, respectively, of the negative controls. For the sediment extracts, a reduction of acetylcholinesterase activity to about 60% could only be shown for the Vering Canal sediment extracts; this could be correlated to high contents of acetylcholinesterase-inhibiting polycyclic aromatic hydrocarbons (PAHs) as identified by chemical analyses. Co-incubation of the Vering Canal sediment extracts with chlorpyrifos at EC10 concentrations each did not significantly increase the inhibitory effect of chlorpyrifos, indicating that the mode of action of acetylcholinesterase inhibition by the sediment-borne PAHs is different to that of the typical acetylcholinesterase blocker chlorpyrifos. Overall, the study documents that zebrafish embryos represent a suitable model not only to reveal acetylcholinesterase inhibition, but also to investigate various modes of neurotoxic action. PMID:25567057

  8. Analysis of Bio-Obtainable Endocrine Disrupting Metals in River Water and Sediment, Sewage Influent/Effluent, Sludge, Leachate, and Concentrated Leachate, in the Irish Midlands Shannon Catchment

    PubMed Central

    Reid, Antoinette M.; Brougham, Concepta A.; Fogarty, Andrew M.; Roche, James J.

    2009-01-01

    The application of an acid digestion and subsequent solid-phase extraction (SPE) procedure were implemented as preliminary treatments prior to quantifying the levels of potentially endocrine disrupting metals (EDMs) in a variety of solid and liquid matrices. These included (solid) river sediment, leachate sediment and sewage sludge and also (liquid) river water, landfill leachate, concentrated leachate, sewage influent, and sewage effluent, sampled in the Irish Midlands. The total concentrations of cobalt (Co), cadmium (Cd), copper (Cu), chromium (Cr), nickel (Ni), lead (Pb), zinc (Zn), and manganese (Mn), after extraction and preconcentration, were determined by atomic absorption spectroscopy (AAS). Mercury (Hg) in sediment and sludge was determined using cold-vapour atomic fluorescence spectroscopy (AFS). For sewage sludge maximum values (mg/kgdw) of 4700 Ni, 1642 Mn, 100.0 Cd, 3400 Zn, 36.70 Co, 750.0 Pb, 485.8 Cr, and 1003 Cu were determined whilst in leachate sediment, maximum values (mg/kgdw) of 32.10 Ni, 815.0 Mn, 32.78 Cd, 230.3 Zn, 26.73 Co, 3525 Pb, 124.9 Cr, and 50.13 Cu were found. Over several months, the data showed elevated levels in sewage influents, effluents, and sludges compared to a battery of adjacent river water samples and corresponding sediments. There was a definite trend for target values for sediments to be exceeded, while intervention values were only exceeded for cadmium. Overall the pattern in terms of concentration was sewage > leachate > river matrices. A nonparametric assessment of the effect of sewage treatment method on median metal levels in sludge revealed statistically significant differences at the 95% level of confidence for Co, Cr, and Hg and at the 90% level of confidence for Cd. PMID:20150974

  9. Pyrethroid insecticide concentrations and toxicity in streambed sediments and loads in surface waters of the San Joaquin Valley, California, USA

    USGS Publications Warehouse

    Domagalski, J.L.; Weston, D.P.; Zhang, M.; Hladik, M.

    2010-01-01

    Pyrethroid insecticide use in California, USA, is growing, and there is a need to understand the fate of these compounds in the environment. Concentrations and toxicity were assessed in streambed sediment of the San Joaquin Valley of California, one of the most productive agricultural regions of the United States. Concentrations were also measured in the suspended sediment associated with irrigation or storm-water runoff, and mass loads during storms were calculated. Western valley streambed sediments were frequently toxic to the amphipod, Hyalella azteca, with most of the toxicity attributable to bifenthrin and cyhalothrin. Up to 100% mortality was observed in some locations with concentrations of some pyrethroids up to 20 ng/g. The western San Joaquin Valley streams are mostly small watersheds with clay soils, and sediment-laden irrigation runoff transports pyrethroid insecticides throughout the growing season. In contrast, eastern tributaries and the San Joaquin River had low bed sediment concentrations (<1 ng/g) and little or no toxicity because of the preponderance of sandy soils and sediments. Bifenthrin, cyhalothrin, and permethrin were the most frequently detected pyrethroids in irrigation and storm water runoff. Esfenvalerate, fenpropathrin, and resmethrin were also detected. All sampled streams contributed to the insecticide load of the San Joaquin River during storms, but some compounds detected in the smaller creeks were not detected in the San Joaquin River. The two smallest streams, Ingram and Hospital Creeks, which had high sediment toxicity during the irrigation season, accounted for less than 5% of the total discharge of the San Joaquin River during storm conditions, and as a result their contribution to the pyrethroid mass load of the larger river was minimal. ?? 2010 SETAC.

  10. Electron donor concentrations in sediments and sediment properties at the agricultural chemicals team research site near New Providence, Iowa, 2006-07

    USGS Publications Warehouse

    Maharjan, Bijesh; Korom, Scott F.; Smith, Erik A.

    2013-01-01

    The concentrations of electron donors in aquifer sediments are important to the understanding of the fate and transport of redox-sensitive constituents in groundwater, such as nitrate. For a study by the U.S. Geological Survey National Water-Quality Assessment Program, 50 sediment samples were collected from below the water table from 11 boreholes at the U.S. Geological Survey Agricultural Chemicals Team research site near New Providence, Iowa, during 2006-07. All samples were analyzed for gravel, sand (coarse, medium, and fine), silt, clay, Munsell soil color, inorganic carbon content, and for the following electron donors: organic carbon, ferrous iron, and inorganic sulfide. A subset of 14 sediment samples also was analyzed for organic sulfur, but all of these samples had concentrations less than the method detection limit; therefore, the presence of this potential electron donor was not considered further. X-ray diffraction analyses provided important semi-quantitative information of well-crystallized dominant minerals within the sediments that might be contributing electron donors.

  11. Effect of Wildfire on Sediment Sorting in a Steep Channel

    NASA Astrophysics Data System (ADS)

    Florsheim, J. L.; Chin, A.; O'Hirok, L.; Storesund, R.

    2014-12-01

    Wildfire is an external forcing factor in the landscape. In chaparral environments, wildfire initiates transport of well-sorted fine sediment through dry-ravel processes on hillslopes and facilitates delivery of sediment to stream channels. In turn, this periodic post-fire sediment influx governs sorting of channel-bed material during subsequent floods that mobilize and transport the sediment downstream. We investigated the effects of the May 2013 Springs Wildfire in the Santa Monica Mountains in semi-arid southern California with field measurements and terrestrial LiDAR scanning. Before the fire, sediment sorting within the heterogeneous bed material present in Big Sycamore Creek was controlled by organized step-pool bedforms. Boulders formed steps with relatively finer cobbles, gravel, and sand filling the pools. Before the fire, the grain size distribution present in the substrate between boulder steps was relatively coarse (D84 = 250 mm), in contrast to that in the influx of sediment contributed by post-fire dry-ravel processes deposited at channel margins (D84 = 8 mm). Flow shear stress during one small flood in 2014 (post-fire) was adequate to mobilize fine dry ravel- related sediment. Transport capacity was sufficient to mobilize and transport this sediment within a study reach; however, it was not adequate to flush the fine material downstream. Shear stress required to mobilize sediment contributed by dry ravel was substantially less than that required to transport the substrate material present before the wildfire. The small flood deposited fine sediment (D84 = 16 mm) as flow lost capacity. Resulting deposition buried bedforms, changing the step-pool profile to a plane bed. The relatively poorly sorted, coarse, rough bed changed to a well sorted, fine, smooth, bed. These changes have implications for sediment transport dynamics and aquatic ecology. In steep, semi-arid, chaparral fluvial systems, sediment derived from dry-ravel processes influences the

  12. Sorption and degradation of triclosan in sediments and its effect on microbes.

    PubMed

    Huang, Xiaolong; Wu, Chenxi; Hu, Hongjuan; Yu, Yuhe; Liu, Jiantong

    2015-06-01

    Sorption and degradation behavior of triclosan (TCS) and its effect on microbes were studied in three sediments spiked at different concentration levels (1, 10, and 100 μg g(-1)). TCS showed a strong affiliation to all the sediments with linear adsorption coefficients (Kd) that varied from 220 to 1092 L g(-1), and the adsorption capacity is related to the total organic carbon (TOC) contents of the sediments. The half-lives of TCS varied from 55 to 239 days, and were longer in sediment with higher Kd. TCS showed minor effect on the activities of fluorescein diacetate hydrolase, dehydrogenase, alkaline phosphatase, and urease in the 1 μg g(-1) treatment, but at higher levels, a short-term effect was observed followed by a rapid recovery except the urease activity in sediment with the lowest adsorption capacity. PCA plots of phospholipid fatty acid showed that the phenotypic community in sediments with low TOC were more sensitive to TCS. A positive relation between bacterial biomass and total microbial biomass suggests that changes of bacteria biomass were responsible for changes of total microbial biomass in treatments. Denaturing gradient gel electrophoresis analysis of the 16S rDNA showed that the bacterial community structure deviated further away from the control at higher TCS concentration levels, with similarity coefficients in Un-weighted Pair Group Mathematics Average clustering between control and 100 μg g(-1) treatment varied from 0.38 to 0.73. Both degradation rate and toxic effects of TCS decreased in sediment with higher sorption capacity, which can be attributed to a reduced bioavailablity. PMID:25770654

  13. Effect of salinity on heavy metal mobility and availability in intertidal sediments of the Scheldt estuary

    NASA Astrophysics Data System (ADS)

    Du Laing, G.; De Vos, R.; Vandecasteele, B.; Lesage, E.; Tack, F. M. G.; Verloo, M. G.

    2008-05-01

    The effect of the flood water salinity on the mobility of heavy metals was studied for intertidal sediments of the Scheldt estuary (Belgium). Soils and sediments of 4 sampling sites were flooded with water of different salinities (0.5, 2.5, and 5 g NaCl L -1). Metal concentrations were monitored in pore water and surface water. To study the potential effects of flood water salinity on metal bioavailability, duckweed ( Lemna minor) was grown in the surface water. The salinity was found to primarily enhance the mobility of Cd and its uptake by duckweed. Cadmium concentrations in pore water of soils and sediments and surrounding surface waters significantly exceeded sanitation thresholds and quality standards during flooding of initially oxidized sediments. Moreover, the effect was observed already at lower salinities of 0.5 g NaCl L -1. This implies that risks related to Cd uptake by organisms and Cd leaching to ground water are relevant when constructing flooding areas in the brackish zones of estuaries. These risks can be reduced by inducing sulphide precipitation because Cd is then immobilised as sulphide and its mobility becomes independent of flood water salinity. This could be achieved by permanently flooding the polluted sediments, because sulphates are sufficiently available in the river water of the brackish part of the estuary.

  14. Effect of Cosolutes on the Sorption of Phenanthrene onto Mineral Surface of River Sediments and Kaolinite

    PubMed Central

    2014-01-01

    Sorption of phenanthrene onto the natural sediment with low organic carbon content (OC%), organic-free sediment, and kaolinite was investigated through isotherm experiments. Effects of cosolutes (pyrene, 4-n-nonyphenol (NP), and humic acid (HA)) on phenanthrene sorption were also studied by comparing apparent solid-water distribution coefficients (Kdapp) of phenanthrene. Two addition sequences, including “cosolute added prior to phenanthrene” and “cosolute and phenanthrene added simultaneously,” were adopted. The Freundlich model fits phenanthrene sorption on all 3 sorbents well. The sorption coefficients on these sorbents were similar, suggesting that mineral surface plays an important role in the sorption of hydrophobic organic contaminants on low OC% sediments. Cosolutes could affect phenanthrene sorption on the sorbents, which depended on their properties, concentrations, and addition sequences. Pyrene inhibited phenanthrene sorption. Sorbed NP inhibited phenanthrene sorption at low levels and promoted sorption at high levels. Similar to NP, effect of HA on phenanthrene sorption onto the natural sediment depended on its concentrations, whereas, for the organic-free sediment and kaolinite, preloading of HA at high levels led to an enhancement in phenanthrene Kdapp while no obvious effect was observed at low HA levels; dissolved HA could inhibit phenanthrene sorption on the two sorbents. PMID:25147865

  15. Effects of sedimentation on soil nutrient dynamics in riparian forests.

    PubMed

    Lockaby, B G; Governo, R; Schilling, E; Cavalcanti, G; Hartsfield, C

    2005-01-01

    The influence of sedimentation rates on biogeochemistry of riparian forests was studied near ephemeral streams at Fort Benning, GA. Upper reaches of seven ephemeral streams had received varying rates of sedimentation stemming from erosion along unpaved roadways at the military installation. Two reference catchments were also included in the study. Decomposition of foliar litter, microbial C and N, N mineralization, and arthropod populations were compared within and among catchments. Rates of sedimentation over the past 25 yr ranged from 0 in references to 4.0 cm yr(-1). Decomposition rates declined exponentially with sedimentation rates as low as 0.20 to 0.32 cm yr(-1) and appeared to reach an equilibrium at a sedimentation rate of 0.5 cm yr(-1). Nitrogen mineralization and microbial C and N followed the same trend. Sedimentation had no discernible effect on arthropod populations. These data suggest that biogeochemical cycles may be altered by sedimentation rates that commonly occur in some floodplain forests. PMID:15647569

  16. Effects of sample homogenization on solid phase sediment toxicity

    SciTech Connect

    Anderson, B.S.; Hunt, J.W.; Newman, J.W.; Tjeerdema, R.S.; Fairey, W.R.; Stephenson, M.D.; Puckett, H.M.; Taberski, K.M.

    1995-12-31

    Sediment toxicity is typically assessed using homogenized surficial sediment samples. It has been recognized that homogenization alters sediment integrity and may result in changes in chemical bioavailability through oxidation-reduction or other chemical processes. In this study, intact (unhomogenized) sediment cores were taken from a Van Veen grab sampler and tested concurrently with sediment homogenate from the same sample in order to investigate the effect of homogenization on toxicity. Two different solid-phase toxicity test protocols were used for these comparisons. Results of amphipod exposures to samples from San Francisco Bay indicated minimal difference between intact and homogenized samples. Mean amphipod survival in intact cores relative to homogenates was similar at two contaminated sites. Mean survival was 34 and 33% in intact and homogenized samples, respectively, at Castro Cove. Mean survival was 41% and 57%, respectively, in intact and homogenized samples from Islais Creek. Studies using the sea urchin development protocol, modified for testing at the sediment/water interface, indicated considerably more toxicity in intact samples relative to homogenized samples from San Diego Bay. Measures of metal flux into the overlying water demonstrated greater flux of metals from the intact samples. Zinc flux was five times greater, and copper flux was twice as great in some intact samples relative to homogenates. Future experiments will compare flux of metals and organic compounds in intact and homogenized sediments to further evaluate the efficacy of using intact cores for solid phase toxicity assessment.

  17. 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. PMID:26199002

  18. The effects of highway construction on sediment discharge into Blockhouse Creek and Steam Valley Run, Pennsylvania

    USGS Publications Warehouse

    Hainly, Robert A.

    1980-01-01

    Stream relocation and diversion methods were successful in limiting the amount of sediment discharged by the new channels. Physical sediment-control methods limited sediment discharge during baseflow periods and small storms. Coarse sediments especially were controlled by these methods. The most effective method of sediment control was limiting the amount of time that the construction-area soils were exposed. (USGS)

  19. Spiking sediment with organochlorines for toxicity testing

    SciTech Connect

    Murdoch, M.H.; Chapman, P.M.; Norman, D.M.; Quintino, V.M.

    1997-07-01

    Sediment toxicity testing integrates responses to sediment variables and hence does not directly indicate cause and effect. One tool for determining cause and effect is sediment spiking, in which relatively uncontaminated sediment is amended with known amounts of contaminants, then tested for toxicity. However, sediment spiking methods vary considerably. The present study details appropriate methodologies (dry and wet spiking) for amending sediments with a range of organic contaminant concentrations, i.e., polychlorinated biphenyl (PCB). Target and actual concentrations were similar. A dose-response was determined, but PCB was not toxic in an acute sediment toxicity test. Chronic testing of these same sediments is reported in a companion article in this issue.

  20. [Effects of Perfluoroalkyl Substances on the Microbial Community Structure in Surface Sediments of Typical River, China].

    PubMed

    Sun, Ya-jun; Wang, Tie-yu; Peng, Xia-wei; Wang, Pei

    2015-07-01

    In order to reveal the relationship between Perfluoroalkyl substances (PFASs) contamination and the bacterial community composition, surface sediment samples were collected along the Xiaoqing River in Shandong Province in April and July 2014 (XQ1-XQ10), where many PFASs manufacturers were located. PFASs were quantified by HPLC/MS-MS, related environmental factors affecting the microbial community structure were measured, and the microbial community structure in surface sediments was measured by the second-generation sequencing technology Illumina MiSeq. The results not only revealed the degree of PFASs pollution in the sediments of Xiaoqing River, but also illustrated the relationship between PFASs pollution and the microbial community structure. Among the twelve kinds of PFASs detected in this study, PFOA was the predominant compound, and the highest PFOA concentrations were detected in the sample of XQ5 (April: 456. 2 ng. g-1; July: 748.7 ng . g-1) located at the downstream of Xiaoqing River with many fluoropolymer producing facilities. PFOA contamination was the main factor affecting the microbial community structure in April, accordingly community richness and evenness were significantly negatively correlated with PFOA levels. The abundance of Thiobacillus increased with the increasing PFOA concentration in the sediment PFOA. This suggested that Thiobacillus was sensitive to PFOA pollution and might be the potential indicator to reveal the degree of PFOA pollution in sediment. When the concentrations of PFOA were below 100 ng . g-1, no significant effects on the microbial community structure were observed. PMID:26489317

  1. Effects of storage temperature and duration on toxicity of sediments assessed by Crassostrea gigas oyster embryo bioassay

    SciTech Connect

    Beiras, R.; His, E.; Seaman, M.N.L.

    1998-10-01

    The effects of temperature and duration of storage on the toxicity of estuarine sediments were investigated with the Crassostrea gigas oyster embryo bioassay. Sediments ranging from unpolluted (controls) to extremely polluted with heavy metals (>100 ppm Hg, Cu, Zn, and Pb) and total hydrocarbons (>1,000 ppm) were collected from sites in southwest France and northern Spain, Control sediments were toxic only at the highest concentrations tested and after freezing in liquid nitrogen ({minus}196 C). Polluted sediments significantly reduced the success of oyster embryogenesis. Analysis of variance showed that the effect of storage temperature on toxicity increased with the prolongation of storage. Prolonged storage of fresh (4 C) sediments resulted in a loss of toxicity, which was more rapid in the less-polluted sediments. Deep-frozen sediments ({minus}196 C) were highly toxic regardless of origin and storage time, and because deep-freezing causes spurious toxicity in the control samples, it cannot be recommended for toxicological studies. In the context of the assessment of sediment toxicity by embryo-larval bioassays, fresh (4 C) storage is recommended when sediments need to be stored for no longer than a few days. The advisable duration of fresh storage to avoid false-negative results is directly related to the degree of toxicity. Should the sediments require prolonged storage, freezing at {minus}20 C appears to be the best choice.

  2. RECOLONIZATION OF SEDIMENT-ASSOCIATED MICROALGAE AND EFFECTS OF ESTUARINE INFAUNA ON MICROALGAL PRODUCTION

    EPA Science Inventory

    Experiments were performed to determine the rate of recolonization of sediment-associated microalgae and effects of infauna on microalgal biomass and production. Estuarine sediment was defaunated and transplanted to the field and the laboratory. Recolonization of sediment by flor...

  3. EFFECTS OF NATURAL SEDIMENT FEATURES ON SURVIVAL OF THE PHOXOCEPHALID AMPHIPOD, RHEPOXYNIUS ABRONIUS

    EPA Science Inventory

    Effects of sediment particle size and water content on the survival of the amphipod. hepoxynius abronius were examined by manipulating these natural sediment features within static laboratory microcosms. ean amphipod survival in fine uncontaminated field sediments (>/ 80% silt-cl...

  4. Developments in the SediView Technique for the processing of ADCP backscatter data to extract suspended sediment concentration profiles in flocculated sediments

    NASA Astrophysics Data System (ADS)

    Taylor, Jon; Manning, Andrew; Crossouard, Neil

    2014-05-01

    From its appearance in the 1980's researchers have recognised the possibilities offered by Acoustic Doppler Current Profiler's (ADCP's) as a means of obtaining information on fluid motion and concentration profiles in both muddy and sandy environments. To date much research effort has been directed in using ADCP's to indirectly observe variations in sandy sediments in suspension using the intensity of the backscattered energy returned from an ADCP and indeed to applications involving mixed suspensions of Sandy and Silty sediments. Studies of naturally flocculating sediment suspensions have however been limited due to practical difficulties in obtaining measurements of floc properties and the incomplete understanding of the interaction taking place between high frequency sound waves and the flocculated particles whilst those that are available have tended to be based on academic studies utilising multi-frequency acoustic sensors rather than the more ubiquitous Acoustic Doppler profilers used in commercial marine monitoring applications and hence their findings are limited in their application. In response to the need to provide water column concentration estimates for engineering applications the Sediview™ method was developed as a means of analysing acoustic backscatter data collected using standard ADCP profilers by means of a robust field methodology supported by software tools and the approach been applied to datasets collected in estuarine and fluvial environments worldwide through it's application on dredging and maritime engineering projects. The poster describes the application of Sediview™ methodology to the application of determining sediment concentration estimates from flocculated sediments measured at a site located within the Turbidity Maximum Zone of the Thames Estuary, UK, and in particular the application of a dual frequency approach to the problem. The experimental investigations described focused on the Acoustic backscatter from ADCPs

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

    PubMed

    Li, Xiaofei; Hou, Lijun; Li, Ye; Liu, Min; Lin, Xianbiao; Cheng, Lv

    2016-10-01

    Polycyclic aromatic hydrocarbons (PAHs) and black carbon (BC) have attracted many attentions, especially in the coastal environments. In this study, spatiotemporal distributions of PAHs and BC, and the correlations between BC and PAHs were investigated in the intertidal sediments of China coastal zones. BC in sediments was measured through dichromate oxidation (BCCr) and thermal oxidation (BCCTO). The concentrations of BCCr in the intertidal sediments ranged between 0.61 and 6.32mgg(-1), while BCCTO ranged between 0.57 and 4.76mgg(-1). Spatial variations of δ(13)C signatures in TOC and BC were observed, varying from -21.13‰ to -24.87‰ and from -23.53‰ to -16.78‰, respectively. PAH contents of sediments ranged from 195.9 to 4610.2ngg(-1) in winter and 98.2 to 2796.5ngg(-1) in summer, and significantly seasonal variations were observed at most sampling sites. However, the results of potential toxicity assessment indicated low ecological risk in the intertidal sediments of China coastal zones. Greater concentrations of PAHs measured in the sediments of estuarine environments indicated that rivers runoff may have been responsible for the higher PAH pollution levels in the intertidal sediments of China coastal zones. Pearson's correlation analysis suggested that pyrogenic compounds of PAH were significantly related to BC, due to that both BC and these compounds derived mainly from the combustion process of fossil fuels and biomass. Overall, increasing energy consumptions caused by anthropogenic activities can contribute more emissions of BC as well as PAHs and thus improve the importance of BC in indicating pyrogenic compounds of PAHs in the intertidal sediments of China coastal zones. PMID:27266522

  6. Elevated Concentrations of Primordial Radionuclides in Sediments from the Reedy River and Surrounding Creeks in Simpsonville, South Carolina

    SciTech Connect

    Powell, B A; Hughes, L D; Soreefan, A M; Falta, D; Wall, M; DeVol, T A

    2006-12-27

    A gamma-ray survey and analysis of sixteen riverbed samples from the Reedy River watershed near Simpsonville, SC were conducted and compared with national and international studies of primordial radionuclides. The study reported here follows on a recent discovery of anomalously high uranium concentrations in several private well waters in the area near Simpsonville, SC. A HPGe spectrometer was used for quantification of gamma emitting radionuclides in the sediments. All sediments contained radionuclides from the uranium and thorium series as well as {sup 40}K. Uranium-238 concentrations in sediment samples ranged from 11.1 to 74.2 Bq kg{sup -1}. The measured radionuclide concentrations were compared with data from UNSCEAR and NURE reports. The river and stream sediment data were augmented by in situ NaI(Tl) gamma-ray spectrometer measurements. Comparisons between the ex-situ and in-situ measurements indicate equivalently distributed uranium in the surface soils and stream sediments, the source of which is likely attributed to the monazite belts that are known to exist in the area.

  7. Phosphate concentration and association as revealed by sequential extraction and microprobe analysis: The case of sediments from two Argentinean reservoirs

    NASA Astrophysics Data System (ADS)

    Borgnino, L.; Orona, C.; Avena, M.; Maine, M. A.; RodríGuez, A.; de Pauli, C. P.

    2006-01-01

    This article reports the general characteristics of the sediments of two Argentinean reservoirs, which are used for water supply. The chemical composition, granulometry, and specific surface area are presented together with a study of total phosphate concentration and phosphate association by combining sequential extraction and microprobe analysis. In general, the sediments of both reservoirs have similar characteristics. Sequential extraction reveals that the main P fractions in the studied sediments are Ca-bound phosphate in river mouths and Fe-bound phosphate in the rest of the reservoir stations. Microprobe analysis appears to be an important complementary technique to sequential extraction. Combined with chemical fractionation and specific surface area measurements, these analyses indicate that Ca-bound phosphate is mainly distributed within grains or particles highly concentrated in Ca and P, whereas Fe-bound phosphate is rather homogeneously distributed in the sediments at the surface of fine particles. Microprobe analyses also revealed an important coating of phyllosilicate surfaces with Fe (hydr)oxides, which explains the good correlation found between Fe-bound phosphate, clay fraction, and specific surface area. The role of sediments as a potential source of phosphate is discussed in terms of P association in the solid phase and dissolved oxygen concentration profiles in the water column.

  8. Multidecadal Field Data Support Intimate Links between Phytoplankton Dynamics and PCB Concentrations in Marine Sediments and Biota.

    PubMed

    Everaert, Gert; De Laender, Frederik; Goethals, Peter L M; Janssen, Colin R

    2015-07-21

    We analyzed three decades of field observations in the North Sea with additive models to infer spatiotemporal trends of chlorophyll a concentration, sediment organic carbon content, and polychlorinated biphenyls (PCBs) concentrations in mussels and sediments. By doing so, we separated long-term changes in PCB concentrations from seasonal variability. Using the inferred seasonal variability, we demonstrated that phytoplankton blooms in spring and autumn correspond to the annual maxima of the organic carbon content (r = 0.56; p = 0.004) and the PCB concentrations in sediments (r = 0.57; p = 0.004). Furthermore, we found a negative correlation between the PCB concentrations in sediments and in blue mussels (Mytilus edulis; r = -0.33, p = 0.012), which is probably related to the cleansing of the dissolved PCB phase driven by sinking organic matter during phytoplankton blooms and the filter-feeding behavior of the blue mussel. The present research demonstrates the role of seasonal phytoplankton dynamics in the environmental fate of PCBs at large spatiotemporal scales. PMID:26079074

  9. Effects of sediments on the reproductive cycle of corals.

    PubMed

    Jones, R; Ricardo, G F; Negri, A P

    2015-11-15

    Dredging, river plumes and natural resuspension events can release sediments into the water column where they exert a range of effects on underlying communities. In this review we examine possible cause-effect pathways whereby light reduction, elevated suspended sediments and sediment deposition could affect the reproductive cycle and early life histories of corals. The majority of reported or likely effects (30+) were negative, including a suite of previously unrecognized effects on gametes. The length of each phase of the life-cycle was also examined together with analysis of water quality conditions that can occur during a dredging project over equivalent durations, providing a range of environmentally relevant exposure scenarios for future testing. The review emphasizes the need to: (a) accurately quantify exposure conditions, (b) identify the mechanism of any effects in future studies, and (c) recognize the close interlinking of proximate factors which could confound interpretation of studies. PMID:26384866

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

    SciTech Connect

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

    1993-01-01

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

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

    SciTech Connect

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

    1993-01-01

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

  12. Remote sensing of suspended sediment concentration, flow velocity, and lake recharge in the Peace-Athabasca Delta, Canada

    NASA Astrophysics Data System (ADS)

    Pavelsky, Tamlin M.; Smith, Laurence C.

    2009-11-01

    The transport of fine sediment, carried in suspension by water, is central to the hydrology, geomorphology, and ecological functioning of river floodplains and deltas. An extensive new field data set for the Peace-Athabasca Delta (PAD), Canada quantifies robust positive relationships between in situ suspended sediment concentration (SSC) and remotely sensed visible/near-infrared reflectance. These relationships are exploited using SPOT and ASTER satellite images to map suspended sediment concentrations across the PAD for four days in 2006 and 2007, revealing strong variations in water sources and flow patterns, including flow reversals in major distributaries. Near-daily monitoring with 276 MODIS satellite images tracks hydrologic recharge of floodplain lakes, as revealed by episodic infusions of sediment-rich water from the Athabasca River. The timing and magnitude of lake recharge are linked to springtime water level on the Athabasca River, suggesting a system sensitive to changes in river flow regime. Moreover, recharge timing differentiates lakes that are frequently and extensively recharged from those recharged more rarely. Finally, we present a first estimation of river flow velocity based on remotely sensed SSC, though saturation may occur at velocities >0.6 m/s. Viewed collectively, the different remote sensing methodologies presented here suggest strong value for visible/near-infrared remote sensing of suspended sediment to assess hydrologic and sediment transport processes in complex flow environments. Field observations including nephelometric turbidity, specific conductivity, water temperature, Secchi disk depth, suspended sediment concentration, and water level are archived at the Oak Ridge National Laboratory Distributed Active Archive Center for Biogeochemical Dynamics (available at http://daac.ornl.gov//HYDROCLIMATOLOGY/guides/PAD.html).

  13. EFFECTS OF VEGETATION ON TURBULENCE, SEDIMENT TRANSPORT AND STREAM MORPHOLOGY

    SciTech Connect

    Neary, Vincent S

    2012-01-01

    Vegetation, from an individual stem to multiple stems in various configurations, profoundly alters turbulent flows. These alterations influence sediment transport and stream morphology, but depend on complex interactions and relationships between flow, plants and sediment properties. This is illustrated for three case studies that represent a variety of macrophyte patterns and scales in the environment: flows through simulated uniformly distributed plant stems, emergent and submerged; flows with alternating simulated stem patches; and flow around an isolated stem in a flood plain. The emergent case demonstrates that when density is sparse the mean velocity and turbulence intensities vary horizontally around the stems, which would promote a heterogeneous bedform morphology. However, it is still unclear how density, submergence ratio, and flow Reynolds number, in combination, influence interference effects, vortex shedding and dissipation, and velocity, pressure and lift fluctuations that affect sediment entrainment. The submerged case demonstrates significant reduction of the mean velocity, turbulence intensities, and turbulent shear near the bed compared to an unobstructed flow and supports numerous observations that vegetation promotes deposition or stabilizes bed sediments. The case of alternating emergent vegetation patches illustrates how vegetation adjusts the bed promoting scour in open water and deposition within the patches. The isolated stem case illustrates the variety of coherent structures generated, their complex interaction, and their role in specific sediment transport phenomena observed. Additional research is required, however, to quantify thresholds and relationships for flow-vegetation-sediment interactions so that aquatic macrophyte plantings can be used more effectively in water resource management.

  14. Effect of the resuspension technique on distribution of the heavy metals in sediment and suspended particulate matter.

    PubMed

    Pourabadehei, Mehdi; Mulligan, Catherine N

    2016-06-01

    Harbour areas play important roles in the economy worldwide. Human activities, however, in those areas, generate contamination, which mostly accumulates in sediments. On the other hand, harbour areas have been facing deposition of significant amounts of sediment each year. As a consequence, shallowness and accumulation of contaminants in sediment become challenging issues in harbours. Among the various management options for remediation of contaminated sediments in harbours, resuspension technique was introduced as a new approach to address those issues. The concept of the resuspension method is that finer sediments have a greater tendency to adsorb the contamination. Therefore, removing the finer sediments instead of dredging the whole contaminated area is the main goal of the resuspension technique. The objective of this paper was to evaluate the effect of the resuspension method on reducing the concentration of contamination and distribution of heavy metals in sediment and suspended particulate matter. The resuspension method was successful in reducing the concentration of seven selected heavy metals (Cr, Ni, Cu, Zn, As, Cd and Pb) by removing just 4% of the contaminated sediment. The contamination intensity in the sediment, presented by geoaccumulation index, was reduced for Cd and Pb as the main contaminants by 26 and 28 percent and the rest of the selected heavy metals returned to the natural level. The results of the sequential extraction tests and enrichment factor implied that the resuspension technique is capable of decreasing the risk of remobilization of heavy metals in the aquatic ecosystem. PMID:27010167

  15. An Investigation of Effective Discharge for Suspended Sediment by Level III Ecoregion

    NASA Astrophysics Data System (ADS)

    Heins, A.; Simon, A.

    2002-12-01

    for seven ecoregions: Coast Range (1) Sierra Nevada (5), Snake River Basin (12), Arizona-New Mexico Plateau (22), Flint Hills (28), Central Irregular Plains (40) and the Mississippi Valley Loess Plains (74). Mean daily flow data for a substantial period of record were divided into 33 logarithmic classes and the percentage occurrence of each of these was computed. The total annual suspended sediment transport was then calculated for each class, using suspended-sediment rating equations generated through regression of instantaneous discharge and suspended sediment concentration historic sample data. The geometric midpoint of the class transporting the greatest annual sediment load was considered to be the effective discharge. Results to date demonstrate in environments as diverse the Sierra Nevada Mountains and the Mississippi Valley Loess Plains, the effective discharge for suspended sediment is close to the 1.5 year flow. In the former ecoregion, the mean recurrence interval of suspended sediment effective discharge was 1.526 years. The eventual aim of this project is to calculate effective discharges for all 2929 USGS gaging stations with sufficient instantaneous suspended sediment and associated discharges measurements. These sites cover all 84 level III ecoregions, permitting environmental and geographic patterns of effective discharge recurrence interval. Calculations will be repeated using higher temporal resolution (15 minute) flow data.

  16. Spatial distribution of radioisotope concentrations in the offshore water and sediment of the Bay of Bengal (Indian Ocean), Bangladesh.

    PubMed

    Bhuiyan, Md Khurshid Alam; Siddique, Mohammad Abdul Momin; Zafar, Mohammad; Mustafa Kamal, Abu Hena

    2014-01-01

    Concentrations of natural and fall-out radionuclides in the offshore seawater and sediment from some parts of the Bay of Bengal, Bangladesh, were determined using a coaxial germanium detector. The average activities of (238)U, (232)Th, (40)K and (137)Cs were recorded as 31.2±5.8, 51.9±9.4, 686.4±170.5 and 0.5±0.6 Bq kg(-1) dry weight, respectively, for sediment, and 4.8±1.2, 5.4±1.2 and 39.1±8.6 Bq L(-1) for (238)U, (232)Th and (40)K, respectively, in seawater. The concentration of (137)Cs in seawater was below the detection limit. The concentration of sediment (238)U was found to be positively correlated with (232)Th ([Formula: see text], p<0.05) and (40)K (r=0.96, p<0.01), while (232)Th was positively correlated with (40)K (r=0.91, p<0.05). In sediment, the concentration of (238)U was negatively correlated (r=-0.86, p<0.05) with sea depth. In the seawater sample, the only significant relationship found was between concentration of (232)Th and water depth (r=-0.86, p<0.05). One-factor analysis of variance (ANOVA) showed that the level of radioisotope concentrations of seawater and sediment was highly significant for (238)U (F=122, df=11, p=0.01), (232)Th (F=143, df=11, p=0.01) and (40)K (F=86, df=11, p=0.01). The results showed that the level of radioactivity decreased from coast to open sea. Imminent threat due to radioactivity was not observed in these parts of the Bay of Bengal. PMID:24090093

  17. Pesticide concentrations in water and sediment and associated invertebrate toxicity in Del Puerto and Orestimba Creeks, California, 2007-2008.

    PubMed

    Ensminger, Michael; Bergin, Rick; Spurlock, Frank; Goh, Kean S

    2011-04-01

    The California's San Joaquin River and its tributaries including Orestimba (ORC) and Del Puerto (DPC) Creeks are listed on the 2006 US EPA Clean Water Act §303(d) list for pesticide impairment. From December 2007 through June 2008, water and sediment samples were collected from both creeks in Stanislaus County to determine concentrations of organophosphorus (OP) and pyrethroid insecticides and to identify toxicity to Ceriodaphnia dubia and Hyalella azteca. OPs were detected in almost half (10 of 21) of the water samples, at concentrations from 0.005 to 0.912 μg L(-1). Diazinon was the most frequently detected OP, followed by chlorpyrifos and dimethoate. Two water samples were toxic to C. dubia; based on median lethal concentrations (LC50), chlorpyrifos was likely the cause of this toxicity. Pyrethroids were detected more frequently in sediment samples (18 detections) than in water samples (three detections). Pyrethroid concentrations in water samples ranged from 0.005 to 0.021 μg L(-1). These concentrations were well below reported C. dubia LC50s, and toxicity was not observed in laboratory bioassays. Cyfluthrin, bifenthrin, esfenvalerate, and λ-cyhalothrin were detected in sediment samples at concentrations ranging from 1.0 to 74.4 ng g(-1), dry weight. At DPC, all but one sediment sample caused 100% toxicity to H. azteca. Based on estimated toxicity units (TUs), bifenthrin was likely responsible for this toxicity and λ-cyhalothrin also contributed. At ORC, survival of H. azteca was significantly reduced in four of the 11 sediment samples. However, pyrethroids were detected in only two of these samples. Based on TUs, bifenthrin and λ-cyhalothrin likely contributed to the toxicity. PMID:20563640

  18. Radionuclide activities and metal concentrations in sediments of the Sebou Estuary, NW Morocco, following a flooding event.

    PubMed

    Laissaoui, A; Mas, J L; Hurtado, S; Ziad, N; Villa, M; Benmansour, M

    2013-06-01

    This study presents metal concentrations (Fe, Mg, Mn, Co, Cu, Zn, Pb, As, Sr and V) and radionuclide activities ((40)K, (137)Cs, (210)Pb, (226)Ra, (228)Ac, (234)Th and (212)Pb) in surface deposits and a sediment core from the Sebou Estuary, Northwest Morocco. Samples were collected in April 2009, about 2 months after a flooding event, and analysed using a well-type coaxial gamma-ray detector and inductively coupled plasma-quadrupole mass spectrometry. Activities of radionuclides and concentrations of almost all elements in surface samples displayed only moderate spatial variation, suggesting homogenous deposition of eroded local soil in response to intense precipitation. Excess (210)Pb displayed relatively constant activity throughout the sediment core, preventing dating and precluding determination of the historical accumulation rates of pollutants at the core site. Some elements showed non-systematic trends with depth and displayed local maxima and minima. Other elements presented relatively systematic concentration trends or relatively constant levels with discrete maxima and/or minima. Except for Mn, Sr and Cr, all metal concentrations in sediment were below levels typical of polluted systems, suggesting little human impact or losses of metals from sediment particles. PMID:23054286

  19. MERCURY CONCENTRATIONS IN SEDIMENT, WATER AND BIOTA COLLECTED FROM NEAR-COASTAL AREAS IMPACTED BY COMMON ESTUARINE STRESSORS

    EPA Science Inventory

    Mercury concentrations in non-commercial organisms indigenous to the Gulf of Mexico are not well characterized particularly when compared to potential sources. In response to this need, mercury levels were determined in sediment, water and various biota in reference and non-refer...

  20. Evaluation of intake efficiencies and associated sediment-concentration errors in US D-77 bag-type and US D-96-type depth-integrating suspended-sediment samplers

    USGS Publications Warehouse

    Sabol, Thomas A.; Topping, David J.

    2013-01-01

    of flume and tow tests alone. This study has three interrelated goals. First, the intake efficiencies of the older US D-77 bag-type and newer, FISP-approved US D-96-type1 depth-integrating suspended‑sediment samplers are evaluated at multiple cross‑sections under a range of actual-river conditions. The intake efficiencies measured in these actual-river tests are then compared to those previously measured in flume and tow tests. Second, other physical effects, mainly water temperature and the duration of sampling at a vertical, are examined to determine whether these effects can help explain observed differences in intake efficiency both between the two types of samplers and between the laboratory and field tests. Third, the signs and magnitudes of the likely errors in suspendedsand concentration in measurements made with both types of samplers are predicted based the intake efficiencies of these two types of depth-integrating samplers. Using the relative difference in isokinetic sampling observed between the US D-77 bag-type and D-96-type samplers during river tests, measured differences in suspended-sediment concentration in a variety of size classes were evaluated between paired equal-discharge-increment (EDI) and equal-width-increment (EWI) measurements made with these two types of samplers to determine whether these differences in concentration are consistent with the differences in concentrations expected on the basis of the 1940s FISP laboratory experiments. In addition, sequential single-vertical depth-integrated samples were collected (concurrent with velocity measurements) with the US D-96-type bag sampler and two different rigidcontainer samplers to evaluate whether the predicted errors in suspended-sand concentrations measured with the US D-96- type sampler are consistent with those expected on the basis of the 1940s FISP laboratory experiments. Results from our study indicate that the intake efficiency of the US D-96-type sampler is superior to that

  1. Mobilization of arsenic from subsurface sediments by effect of bicarbonate ions in groundwater.

    PubMed

    Anawar, Hossain M; Akai, Junji; Sakugawa, Hiroshi

    2004-02-01

    Arsenic leaching by bicarbonate ions has been investigated in this study. Subsurface sediment samples from Bangladesh were treated with different carbonate and bicarbonate ions and the results demonstrate that the arsenic leaching efficiency of the carbonate solutions decreased in the order of Na2CO3>NaHCO3>BaCO3>MnCO3. Sodium carbonate and bicarbonate ions extracted arsenic most efficiently; Na2CO3 leached maximum 118.12 microg/l of arsenic, and NaHCO3, 94.56 microg/l of arsenic from the Ganges delta sediments after six days of incubation. The arsenic concentrations extracted in the batch experiments correlated very well with the bicarbonate concentrations. The kinetics study of arsenic release indicates that arsenic-leaching rate increased with reaction time in bicarbonate solutions. Bicarbonate ions can extract arsenic from sediment samples in both oxic and anoxic conditions. A linear relationship found between arsenic contents in core samples and those in leachates suggests that dissolved arsenic concentration in groundwater is related to the amount of arsenic in aquifer sediments. In batch experiment, bicarbonate solutions effectively extracted arsenic from arsenic adsorbed iron oxyhydroxide, reflecting that bicarbonate solutions may mobilize arsenic from iron and manganese oxyhydroxide in sediments that are ubiquitous in subsurface core samples. Carbonate ion may form complexes on the surface sites of iron hydroxide and substitute arsenic from the surface of minerals and sediments resulting in release of arsenic to groundwater. Like in the batch experiment, arsenic and bicarbonate concentrations in groundwater of Bangladesh correlated very well. Therefore, bicarbonate leaching is presumed to be one important mechanism to mobilize arsenic in bicarbonate dominated reducing aquifer of Bangladesh and other parts of the world as well. PMID:14602108

  2. Concentrations, loads, and yields of total phosphorus, total nitrogen, and suspended sediment and bacteria concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011-13

    USGS Publications Warehouse

    Buck, Stephanie D.

    2014-01-01

    The Poteau Valley Improvement Authority uses Wister Lake in southeastern Oklahoma as a public water supply. Total phosphorus, total nitrogen, and suspended sediments from agricultural runoff and discharges from wastewater treatment plants and other sources have degraded water quality in the lake. As lake-water quality has degraded, water-treatment cost, chemical usage, and sludge production have increased for the Poteau Valley Improvement Authority. The U.S. Geological Survey (USGS), in cooperation with the Poteau Valley Improvement Authority, investigated and summarized concentrations of total phosphorus, total nitrogen, suspended sediment, and bacteria (Escherichia coli and Enterococcus sp.) in surface water flowing to Wister Lake. Estimates of total phosphorus, total nitrogen, and suspended sediment loads, yields, and flow-weighted mean concentrations of total phosphorus and total nitrogen concentrations were made for the Wister Lake Basin for a 3-year period from October 2010 through September 2013. Data from water samples collected at fixed time increments during base-flow conditions and during runoff conditions at the Poteau River at Loving, Okla. (USGS station 07247015), the Poteau River near Heavener, Okla. (USGS station 07247350), and the Fourche Maline near Leflore, Okla. (USGS station 07247650), water-quality stations were used to evaluate water quality over the range of streamflows in the basin. These data also were collected to estimate annual constituent loads and yields by using regression models. At the Poteau River stations, total phosphorus, total nitrogen, and suspended sediment concentrations in surface-water samples were significantly larger in samples collected during runoff conditions than in samples collected during base-flow conditions. At the Fourche Maline station, in contrast, concentrations of these constituents in water samples collected during runoff conditions were not significantly larger than concentrations during base

  3. Uranium hydrogeochemical and stream sediment reconnasissance of the Trinidad NTMS Quadrangle, Colorado, including concentrations of forty-two additional elements

    SciTech Connect

    Shannon, S.S. Jr.

    1980-05-01

    Uranium and other elemental data resulting from the Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) of the Trinidad National Topographic Map Series (NTMS) quadrangle, Colorado, by the Los Alamos Scientific Laboratory (LASL) are reported herein. This study was conducted as part of the United States Department of Energy's National Uranium Resource Evaluation (NURE), which is designed to provide improved estimates of the availability and economics of nuclear fuel resources and to make available to industry information for use in exploration and development of uranium resources. The HSSR data will ultimately be integrated with other NURE data (e.g., airborne radiometric surveys and geological investigations) to complete the entire NURE program. This report is a supplement to the HSSR uranium evaluation report for the Trinidad quadrange (Morris et al, 1978), which presented the field and uranium data for the 1060 water and 1240 sediment samples collected from 1768 locations in the quadrangle. The earlier report contains an evaluation of the uranium concentrations of the samples as well as descriptions of the geology, hydrology, climate, and uranium occurrences of the quadrange. This supplement presents the sediment field and uranium data again and the analyses of 42 other elements in the sediments. All uranium samples were redetermined by delayed-neutron counting (DNC) when the sediment samples were analyzed for 31 elements by neutron activation. For 99.6% of the sediment samples analyzed, the differences between the uranium contents first determined (Morris et al, 1978) and the analyses reported herein are less than 10%.

  4. Bacterial concentration and diversity in fresh tropical shrimps (Penaeus notialis) and the surrounding brackish waters and sediment.

    PubMed

    Dabadé, D Sylvain; Wolkers-Rooijackers, Judith C M; Azokpota, Paulin; Hounhouigan, D Joseph; Zwietering, Marcel H; Nout, M J Rob; den Besten, Heidy M W

    2016-02-01

    This study aimed at determining bacterial concentration and diversity in fresh tropical shrimps (Penaeus notialis) and their surrounding brackish waters and sediment. Freshly caught shrimp, water and sediment samples were collected in Lakes Nokoue and Aheme in Benin (West Africa) during two periods with different water salinity and temperature. We used complementary culture-dependent and culture-independent methods for microbiota analysis. During both sampling periods, total mesophilic aerobic counts in shrimp samples ranged between 4.4 and 5.9 log CFU/g and were significantly higher than in water or sediment samples. In contrast, bacterial diversity was higher in sediment or water than in shrimps. The dominant phyla were Firmicutes and Proteobacteria in shrimps, Firmicutes, Proteobacteria, and Actinobacteria in water, and Proteobacteria and Chloroflexi in sediment. At species level, distinct bacterial communities were associated with sediment, water and shrimps sampled at the same site the same day. The study suggests that the bacterial community of tropical brackish water shrimps cannot be predicted from the microbiota of their aquatic environment. Thus, monitoring of microbiological quality of aquatic environments might not reflect shrimp microbiological quality. PMID:26656527

  5. Effect of organic carbon and metal accumulation on the bacterial communities in sulphidogenic sediments.

    PubMed

    Bueche, Matthieu; Junier, Pilar

    2016-06-01

    A unique geochemical setting in Lake Cadagno, Switzerland, has led to the accumulation of insoluble metal sulphides in the sedimentary record as the result of past airborne pollution. This offers an exceptional opportunity to study the effect of these metals on the bacterial communities in sediments, and in particular to investigate further the link between metal contamination and an increase in the populations of endospore-forming bacteria observed previously in other metal-contaminated sediments. A decrease in organic carbon and total bacterial counts was correlated with an increase in the numbers of endospores in the oldest sediment samples, showing the first environmental evidence of a decrease in nutrient availability as a trigger of sporulation. Proteobacteria and Firmicutes were the two dominant bacterial phyla throughout the sediment, the former in an area with high sulphidogenic activity, and the latter in the oldest samples. Even though the dominant Firmicutes taxa were stable along the sediment core and did not vary with changes in metal contamination, the prevalence of some molecular species like Clostridium sp. was positively correlated with metal sulphide concentration. However, this cannot be generalized to all endospore-forming species. Overall, the community composition supports the hypothesis of sporulation as the main mechanism explaining the dominance of endospore formers in the deepest part of the sediment core, while metal contamination in the form of insoluble metal sulphide deposits appears not to be linked with sporulation as a mechanism of metal tolerance in this sulphidogenic ecosystem. PMID:26780045

  6. Hydrocarbon concentrations in sediments and clams (Rangia cuneata) in Laguna de Pom, Mexico

    SciTech Connect

    Alvarez-Legorreta, T.; Gold-Bouchot, G.; Zapata-Perez, O.

    1994-01-01

    Laguna de Pom is a coastal lagoon within the Laguna de Terminos system in southern Gulf of Mexico. It belongs to the Grijalva-Usumacinta basin, and is located between 18{degrees} 33{prime} and 18{degrees} 38{prime} north latitude and 92{degrees} 01{prime} and 92{degrees} 14{prime} west longitude, in the Coastal Plain physiographic Province of the Gulf. It is ellipsoidal and approximately 10 km long, with a surface area of 5,200 ha and a mean depth of 1.5 m. Water salinity and temperature ranges are 0 to 13 {per_thousand} and 25{degrees} to 31{degrees}C, respectively. Benthic macrofauna is dominated by bivalves such as the clams Rangia cuneata, R. flexuosa, and Polymesoda carolineana. These clams provide the basis of an artisanal fishery, which is the main economic activity in the region. The presence of several oil-processing facilities around the lagoon is very conspicuous, which together with decreasing yields has created social conflicts, with the fishermen blaming the mexican state oil company (PEMEX) for the decrease in the clam population. This work aims to determine if the concentration of hydrocarbons in the clams (R. cuneata) and sediments of Laguna de Pom are responsible for the declining clam fishery. 11 refs., 4 figs., 2 tabs.

  7. Effect of PCB Bioavailability Changes in Sediments on Bioaccumulation in Fish.

    PubMed

    Fadaei, Hilda; Watson, Aaron; Place, Allen; Connolly, John; Ghosh, Upal

    2015-10-20

    In situ sediment amendment with sorbents such as activated carbon (AC) can effectively reduce the bioavailability of hydrophobic organic chemicals such as polychlorinated biphenyls (PCBs). However, there is limited experimental or modeling assessment of how bioavailability changes in sediments impact bioaccumulation in fish - the primary risk driver for exposure to humans and top predators in the aquatic ecosystem. In the present study we performed laboratory aquarium experiments and modeling to explore how PCB sorption in sediments impacted exposure pathways and bioaccumulation in fish. Results showed that freely dissolved PCBs in porewater and overlying water measured by passive sampling were reduced by more than 95% upon amendment with 4.5% fine granular AC. The amendment also reduced the PCB uptake in fish by 87% after 90 days of exposure. Measured freely dissolved concentrations were incorporated in equilibrium and kinetic models for predicting uptake by fish. Predicted uptake using the kinetic model was generally within a factor of 2 for total PCBs measured in fish. The kinetic model output was most sensitive to overlying water PCBs, lipid fraction, and dissolved oxygen concentration (regulating gill ventilation). Our results indicate that by incorporating changes in freely dissolved PCB concentrations in bioaccumulation models it is possible to predict effectiveness of sediment remediation in reducing PCB uptake in fish. PMID:26402889

  8. Data and statistical summaries of background concentrations of metals in soils and streambed sediments in part of Big Soos Creek drainage basin, King County, Washington

    USGS Publications Warehouse

    Prych, E.A.; Kresch, D.L.; Ebbert, J.C.; Turney, G.L.

    1995-01-01

    Twenty-nine soil samples from 14 holes at 9 sites in part of the Big Soos Creek drainage basin in southwest King County, Washington, were collected and analyzed to obtain data on the magnitude and variability of background concentrations of metals in soils. Seven streambed-sediment samples and three streamwater samples from three sites also were collected and analyzed. These data are needed by regulating government agencies to determine if soils at sites of suspected contamination have elevated concentrations of metals, and to evaluate the effectiveness of remediation at sites with known contamination. Concentrations of 43 metals were determined by a total method, and concentrations of 17 metals were determined by a total-recoverable method and two different leaching methods. Metals analyzed for by all methods included most of those on the U.S. Environmental Protection agency list of priority pollutants, plus alluminum, iron, and manganese. Ranges of concentrations of metals determined by the total method are within ranges found by others for the conterminous United States. Concentrations of mercury, manganese, phosphorus, lead, selenium, antimony, and zinc as determined by the total method, and of some of these plus other metals as determined by the other methods were larger in shallow soil (less than 12 inches deep) than in deep soil (greater than 12 inches). Concentrations of metals in streambed sediments were more typical of shallow than deep soils.

  9. Uranium hydrogeochemical and stream sediment reconnaissance of the Newcastle NTMS quadrangle, Wyoming, including concentrations of forty-two additional elements

    SciTech Connect

    Goff, S.J.; Sandoval, W.F.; Gallimore, D.L.; Talcott, C.L.; Martinez, R.G.; Minor, M.E.; Mills, C.F.

    1980-06-01

    During the summer and fall of 1977, 533 water and 1226 sediment samples were collected from 1740 locations within the 18,000 km/sup 2/ area of the Newcastle quadrangle, Wyoming. Water samples were collected from wells and springs; sediment samples were collected from stream channels and from springs. Each water sample was analyzed for uranium, and each sediment sample was analyzed for 43 elements, including uranium and thorium. Uranium concentrations in water samples range from below the detection limit of 0.02 ppB to 702.26 ppB and have a median of 1.73 ppB and a mean of 11.76 ppB. Water samples containing high uranium concentrations (>20 ppB) generally are associated with known uranium mining activity or units known to be uranium bearing. About one-third of the water samples containing high uranium concentrations were collected from locations within the Pumpkin Buttes and Turnercrest-Ross Districts. Nearly half of the water samples containing high uranium concentrations were collected from locations just west of the Monument Hill and Highland Flats-Box Creek Districts. Similar anomalous uranium concentrations in this region have been reported updip from Exxon's Highland uranium deposits. High uranium concentrations were also found associated with the Lance Creek-Old Woman Anticline District.

  10. Phosphorus released from sediment of Dianchi Lake and its effect on growth of Microcystis aeruginosa.

    PubMed

    Liu, Junzhuo; Luo, Xiongxin; Zhang, Naiming; Wu, Yonghong

    2016-08-01

    Phosphorus stored in lake sediments is an inner nutrient source and can be released into overlying water to exacerbate algal blooms. A simulated microcosm of Dianchi Lake was built to investigate phosphorus release from sediments to overlying water and its effect on the growth of Microcystis aeruginosa. The sediments of Dianchi Lake had a total phosphorus (TP) content of 1.7-1.8 mg g(-1) with Ca bound phosphorus (Ca-P, 50-54 %) and organic phosphorus (Org-P, 28-32 %) as the main fractions. The sediments released 8 % of TP into the overlying water with Fe/Al bound phosphorus (Fe/Al-P, 26 %) and Org-P (65 %) being the main fractions released. The phosphorus concentration of the overlying water increased from 0.14-0.16 to 0.28-0.33 mg L(-1). The biomass density of M. aeruginosa was positively correlated (R (2) = 0.825) with the concentration of orthophosphate, which was the predominant bioavailable phosphorus fraction for algal growth. Org-P can be partly utilized by M. aeruginosa but will not cause a bloom. A good understanding of the geochemical cycles of phosphorus is needed for regulating phosphorus release from sediments and thereby reducing the risk of cyanobacterial blooms. PMID:27155834

  11. Characterizing the effects of bisphenol A on sediment-dwelling benthic organisms.

    PubMed

    Staples, Charles; Mihaich, Ellen; Ortego, Lisa; Caspers, Norbert; Klečka, Gary; Woelz, Jan; Hentges, Steven

    2016-03-01

    Bisphenol A (BPA) is a high production volume chemical intermediate used primarily in the production of polycarbonate plastics and epoxy resins. It primarily enters surface water and sediment via effluent discharges during its manufacture and use. The physical properties of BPA suggest that sediment is a potential sink and may result in exposure to benthic organisms. Currently there are no studies measuring the chronic toxicity of BPA to benthic organisms via direct sediment exposure. The present study examined the chronic toxicity of BPA to 3 commonly used test organisms that are generally representative of invertebrates occupying the base of the benthic food web and for which standardized testing protocols are available: the oligochaete Lumbriculus variegatus (mean numbers and biomass), the midge Chironomus riparius (emergence and development rate), and the estuarine amphipod Leptocheirus plumulosus (survival, growth, and reproduction). No-observed-effect concentrations (NOECs) for the 3 species ranged from 12 mg/kg to 54 mg/kg dry weight. All NOEC values were higher than all measured concentrations of BPA in freshwater and marine sediments reported in reliable, fully reported studies from North America and Europe from the 1990s to the present. For the first time, there are studies with BPA measuring the chronic toxicity to 3 taxa of sediment dwelling invertebrates, which are suitable to support region-specific risk assessments. PMID:26297924

  12. A multiple-state discrete-time Markov chain for estimating suspended sediment concentrations in open channel flow

    NASA Astrophysics Data System (ADS)

    Tsai, Christina; Wu, Nai-Kuang

    2015-04-01

    In this study, transport processes of uniform size sediment particles under steady and uniform flow are described by the multi-state discrete-time Markov chain. The multi-state discrete-time Markov chain is employed to estimate the suspended sediment concentration distribution versus water depth for various steady and uniform flow conditions. Model results are validated against available measurement data and the Rouse profile. Moreover, the multi-state discrete-time Markov chain can be used to quantify the average time spent for the flow to reach the dynamic equilibrium of particle deposition and entrainment processes. In the first part of this study, suspended sediment concentration under three different flow conditions are discussed. As the Rouse number decreases, the difference between the suspended sediment concentration estimated by the Markov chain model and the Rouse profile becomes more significant, and such discrepancy can be observed at a larger relative height from the bed. It can be attributed to the fact that the use of the terminal settling velocity in the transport process can lead to underestimation of the model residence probability and overestimation of the deposition probability. In the second part, laboratory experiments are used to validate the proposed multi-state discrete-time Markov chain model. It is observed that it would take more time for the sediment concentration to reach a dynamic equilibrium as the Rouse number decreases. In addition, the flow depth is found to be a contributing factor that impacts the time spent to reach the concentration dynamic equilibrium. It is recognized that the performance of the proposed multi-state discrete-time Markov chain model relies significantly on the knowledge of the vertical distribution of the turbulence intensity.

  13. Impact of seasonal variation on Escherichia coli concentrations in the riverbed sediments in the Apies River, South Africa.

    PubMed

    Abia, Akebe Luther King; Ubomba-Jaswa, Eunice; Momba, Maggy Ndombo Benteke

    2015-12-15

    Many South Africans living in resource-poor settings with little or no access to pipe-borne water still rely on rivers as alternative water sources for drinking and other purposes. The poor microbial quality of such water bodies calls for appropriate monitoring. However, routine monitoring only takes into consideration the microbial quality of the water column, and does not include monitoring of the riverbed sediments for microbial pollution. This study sought to investigate the microbial quality of riverbed sediments in the Apies River, Gauteng Province, South Africa, using Escherichia coli as a faecal indicator organism and to investigate the impact of seasonal variation on its abundance. Weekly samples were collected at 10 sampling sites on the Apies River between May and August 2013 (dry season) and between January and February 2014 (wet season). E. coli was enumerated using the Colilert®-18 Quanti-Tray® 2000 system. All sites tested positive for E. coli. Wastewater treatment work effluents had the highest negative impact on the river water quality. Seasonal variations had an impact on the concentration of E. coli both in water and sediments with concentrations increasing during the wet season. A strong positive correlation was observed between temperature and the E. coli concentrations. We therefore conclude that the sediments of the Apies River are heavily polluted with faecal indicator bacteria and could also harbour other microorganisms including pathogens. The release of such pathogens into the water column as a result of the resuspension of sediments due to extreme events like floods or human activities could increase the health risk of the populations using the untreated river water for recreation and other household purposes. There is therefore an urgent need to reconsider and review the current South African guidelines for water quality monitoring to include sediments, so as to protect human health and other aquatic lives. PMID:26318680

  14. Time Scales in Turbulence and Sediment Concentration Over Mobile Sand Dunes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The relationship between turbulent fluid motions and sediment particles over mobile sand dunes may be better understood by examining the time scales over which the quantities fluctuate. In laboratory experiments performed at the USDA-ARS-National Sedimentation Laboratory, profiles of acoustic backs...

  15. Microplastics in sediments: A review of techniques, occurrence and effects.

    PubMed

    Van Cauwenberghe, Lisbeth; Devriese, Lisa; Galgani, François; Robbens, Johan; Janssen, Colin R

    2015-10-01

    Microplastics are omnipresent in the marine environment and sediments are hypothesized to be major sinks of these plastics. Here, over 100 articles spanning the last 50 year are reviewed with following objectives: (i) to evaluate current microplastic extraction techniques, (ii) to discuss the occurrence and worldwide distribution of microplastics in sediments, and (iii) to make a comprehensive assessment of the possible adverse effects of this type of pollution to marine organisms. Based on this review we propose future research needs and conclude that there is a clear need for a standardized techniques, unified reporting units and more realistic effect assessments. PMID:26095706

  16. The role of acid-volatile sulfide and interstitial water metal concentrations in determining bioavailability of cadmium and nickel from contaminated sediments to the marine polychaete Neanthes arenaceodentata

    SciTech Connect

    Pesch, C.E.; Hansen, D.J.; Boothman, W.S. . Environmental Research Lab.); Berry, W.J. ); Mahony, J.D. . Chemistry Dept.)

    1995-01-01

    This study investigated the influence of acid-volatile sulfide (AVS) and interstitial water (IW) metal concentrations on bioavailability and toxicity of Cd and Ni to an infaunal sediment-ingesting marine worm, Neanthes Arenaceodentata. Ten-d exposures were conducted with sediments, contaminated primarily with Cd and Ni, from Foundry Cove (Hudson River, NY), and with uncontaminated sediments spiked with Cd or Ni. Molar ratios of simultaneously extracted metal (SEM)/AVS ranged from < 0.02 to 44 for Cd-spiked, 0.02 to 241 for Ni-spiked, and <0.06 to 125 for Foundry Cove sediments. In all experiments, significant mortality was not observed when SEM/AVS ratios were <1.0 and interstitial water toxic units (IWTU) were <1.0. In the Cd and Ni-spiked experiments, when SEM/AVS ratios or IWTUs were >1.0, sediments were either lethal or worms did not burrow. Mortality of worms in Foundry Cove sediments was [le] 20%, and worms burrowed in all these sediments. However, IW contained <1.0 TU (Ni + Cd) in all Foundry Cove sediments except one (IWTU = 1.69). Metal concentrations in worms generally increased with increases in sediment metal concentration, SEM/AVS molar ratio, and IW metal concentration. The presence of metal in worms from sediments from SEM/AVS ratios <1.0 may be evidence of release of Cd or Ni from oxidized metal sulfide (a result of burrowing), uptake of metal from ingested sediment, or adsorption to body surfaces. These results support the hypothesis that when the concentration of AVS in sediments exceeds that of divalent metals sediments will not be acutely toxic. However, a greater number of sediments was correctly predicted to be nontoxic when interstitial water metal concentration of <1.0 TU was used.

  17. Methane and carbon dioxide concentrations in sediments and diffusive fluxes at the sediment-water interface from three tropical systems in Brazil during the pre-impoundment phase

    NASA Astrophysics Data System (ADS)

    Abe, D. S.; Sidagis-Galli, C.; Grimberg, D. E.; Blanco, F. D.; Rodrigues-Filho, J. L.; Tundisi, J. G.; Matsumura-Tundisi, T.; Tundisi, J. E.; Cimbleris, A. C.; Damázio, J. M.; Project Balcar

    2013-05-01

    The concentrations of methane and carbon dioxide in the sediments pore water were quantified by gas chromatography in three hydroelectric reservoirs under construction during the pre-impoundment phase. Sediment sampling was performed in ten to twelve stations in each river by a Kajak-Brinkhurst corer coupled to a 3 m long aluminum rod in four seasons. The theoretical diffusive fluxes of these gases at the sediment-water interface were also calculated using the Fick's first law of diffusion. The mean annual concentration and diffusive flux of methane were highest in the sediments of the Xingu River (12.71 ± 3.03 mmol CH4 m-2 and 3.84 ± 0.91 mmol CH4 m-2 d-1), located in the Amazon, influenced by the presence of organic matter originating from the surrounding forest. The mean annual concentration of carbon dioxide was highest in the São Marcos River (71.36 ± 10.36 mmol CO2 m-2), located in an area of cerrado savanna, while the highest diffusive flux of carbon dioxide was observed in the Madeira River (30.23 ± 2.41 mmol CO2 m-2 d-1), which rises in the Andes Cordillera and has a very high water flow. The mean concentration and diffusive flux of carbon dioxide in the three studied systems were much higher (64-98%) in comparison with the methane, influenced by the oxic condition in these lotic systems. Nevertheless, the present study shows that the sediments of these systems, especially in the Xingu River, have significant amount of methane dissolved in the pore water which is being diffused to the overlying water. The information obtained in this study during the pre-filling phase will be important for the calculation of net flows of greenhouse gases after the impoundment of these future reservoirs. This study is part of the Strategic Project "Monitoring Emissions of Greenhouse Gases in Hydroelectric Reservoirs" - Call 099/2008 of the Brazilian Agency of Electric Energy (ANEEL) and sponsored by ELETRONORTE, FURNAS and CHESF.

  18. Eutrophication-driven sediment microbial processes can explain the regional variation in phosphorus concentrations between Baltic Sea sub-basins

    NASA Astrophysics Data System (ADS)

    Lehtoranta, Jouni; Ekholm, Petri; Pitkänen, Heikki

    2008-11-01

    Despite the ecological significance of microbial iron and sulphate reduction in aquatic environments, the processes involved have been poorly studied in Baltic Sea sediments. On the basis of indirect evidence, we conclude that the bottom sediments of the non-stratified and oligotrophic northernmost, and the poorly stratified and mesotrophic next northern, sub-basins of the Baltic have tolerated the external nutrient load rather well, as they are still in a state in which iron reduction and coupled cycling of iron and phosphorus prevail in the surface sediments. Since iron-reducing bacteria are unable to reduce ferric oxides completely, part of the iron-bound phosphorus may be permanently buried in the sediments. The good ability of the sediment to retain phosphorus results in low concentrations of phosphorus in water, a state that in turn promotes phosphorus limitation of primary production. In contrast, the sediments of the nutrient-loaded and stratified sub-basins, the Gulf of Finland (the most eutrophied sub-basin) and the Baltic Proper, appeared to have reached a state in which sulphate reduction is the dominant mineralisation pathway. Sulphate reduction followed by sulphide formation leads to efficient reduction of ferric oxides. Subsequently, iron-bound phosphorus dissolves into the pore water and is transported to the overlying water, whereas iron is buried as sulphides (uncoupled iron and phosphorus cycling). The capacity of sediments to retain phosphorus is limited; high amounts of bioavailable phosphate exist in the water column, primary production tends to be nitrogen limited and extensive blue-green algal blooms are common. We maintain that the decisive factors controlling the above regional distribution of iron and sulphate reduction are the flux of labile organic matter to the sediments and the variation in hydrodynamics. Sulphate reduction will be triggered when the flux of organic matter reaches a critical threshold value, resulting in anoxia at the

  19. Effects of cadmium on sediment processing on members of the Capitella species-complex.

    PubMed

    Méndez, Nuria; Baird, Donald J

    2002-01-01

    The effect of cadmium on sediment processing by laboratory-cultured specimens of Capitella sp I and Capitella sp B was investigated. Specimens were exposed to 0, 60, 90 and 140 microg Cd g(-1) dry weight sediment for a 10 day period (two census days) to observe effects of cadmium on their feeding activity. Under unstressed conditions, Capitella sp I specimens were larger, had higher biomass and produced more fecal pellets than Capitella sp B. Cadmium concentrations had no effect on pellet production and body mass of the studied populations. However, cadmium exposure time significantly affected Capitella sp B pellet production and body mass of both populations following different trends: after 10 days of exposure, the average processed sediment per unit worm mass decreased in Capitella sp I but increased in Capitella sp B. The latter population did not reduce its feeding activity in the presence of cadmium maybe related to the fact that it is derived from a highly polluted environment. This study has shown an unimpaired response of Capitella sp I and Capitella sp B to cadmium in their sediment processing activity, which indicates the potential importance of this species complex in the trophic transfer of metals from sediments to other marine organisms. PMID:12395842

  20. Marine sediment and interstitial water: Effects on bioavailability of cadmium to gills of the clam Protothaca staminea

    SciTech Connect

    Hardy, J.T.; Schmidt, R.L.; Apts, C.W.

    1981-12-01

    A study was made to determine first, the kinetics of cadmium sorption on a natural marine sediment and second, the degree to which this sorption as well as interstitial water might effect bioavailability of cadmium to gills of the clam Protothaca staminea. Surface sediment from Sequim Bay, Washington was labelled with Cd 109 and total cadmium concentration determined by radioassay. Gills were added to three types of exposures: 1) control (0.45 um filtered seawater, 2) sediment interstitial water and 3) washed sediment. Prepared samples of gills were counted in a liquid scintillation counter. Results show that addition of a small quantity of washed sediment to the exposure system reduced cadmium accumulation by gills to only 17% of the control. Interstitial water had no significant effect. 1 table, 3 figures (JMT)

  1. A comparison of instrumental dewatering methods for the separation and concentration of suspended sediment for subsequent trace element analysis

    USGS Publications Warehouse

    Horowitz, A.J.; Elrick, K.A.; Hooper, R.C.

    1989-01-01

    The continuous-flow centrifuges can process whole water at an influent feed rate of 41 per minute; however, when suspended sediment concentrations are low (<30 mg l-1), when small volumes of whole water are to be processed (30 to 401), or when suspended sediment mean grain size is very fine (<10 ??m), influent feed rates of 21 per minute may be more efficient. Tangential-flow filtration can be used to process samples at the rate of 11 per minute. -from Authors

  2. Effects of algal bloom formation, outbreak, and extinction on heavy metal fractionation in the surficial sediments of Chaohu Lake.

    PubMed

    Wang, Shu-guang; Diao, Xiao-jun; He, Lian-sheng

    2015-09-01

    The effects of algal bloom (AB) on the physicochemical and biochemical properties of water and sediment in lakes have been widely studied. However, limited attention has been directed toward the effects of the processes of AB formation, outbreak, and extinction on heavy metal fractionation in sediment. In this study, water and sediment samples were collected from the AB and free algal bloom (FAB) regions of Chaohu Lake from May to September in 2012. The chemical fractionation of seven heavy metals (Cd, Cr, Cu, Mn, Ni, Fe, and Pb) in sediment was determined by using a modified three-step sequential procedure. Evident processes of AB formation, outbreak, and extinction were observed in the AB region, but not in the FAB region. The TN and TP concentrations in water and sediment in the AB region were significantly higher than those in the FAB region. The water DO concentration was higher in the AB region than that in the FAB region before the early stage of the AB outbreak, but an opposite trend was observed in the stages that followed. Metal fractionation in sediment showed that except for Mn and Cu, the majority of metals were in the residual fraction regardless of the AB process. The AB process slightly altered the concentrations of metal fractions, except for reducible Fe and oxidizable Cu. The result showed that AB formation, outbreak, and extinction slightly affected heavy metal fractionation in sediment though water properties were significantly different among AB processes. PMID:25976327

  3. Ecological implications of heavy metal concentrations in the sediments of Burullus Lagoon of Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Chen, Zhongyuan; Salem, Alaa; Xu, Zhuang; Zhang, Weiguo

    2010-02-01

    This paper examines the spatial and temporal distribution of heavy metals (Fe, Al, Cu, Zn, Mn, Cd, Pb and Ni) from three short sediment cores collected from Burullus lagoon of the Nile delta, Egypt. 210Pb and 137Cs measurement is applied to understand sedimentation rate and related chronology. Remarkably low isotopic activities and intensive bioturbation in the lagoonal sediments rendered age determination difficult. Samples with detectable 137Cs in the upper core sediments together with sediment lithology could help infer a sedimentation rate of about 2.0 mm yr -1, thereby indicating post-dam (after 1964) sedimentation of the upper 10-cm core sediments. Our results demonstrate that most heavy metals in the surficial sediments after normalization to Al decrease seaward, showing a function of distance to the sewerage outlet on the inland lake coast. Also, there is an upwardly increasing trend of normalized heavy metals, especially in the upper 10-cm core sediments. Relevancy analysis has identified Mn, Pb and Cd as the diagnostic heavy metals in Burullus lagoon, most likely derived from Tanta and Kafrelsheihk, the major downtowns in the central Nile delta plain, from where wastewaters are directly discharging into the lake via canal networks. Although Burullus lagoon is presently least affected by pollution as compared to other major lagoons of the Nile delta, the increasing quantities of diagnostic metals, especially Mn, are extremely toxic, as they are potentially linked to the risks of digestive issues and pancreatic cancer reportedly. The situation calls for a rational planning for sewerage treatment in the protected Burullus coast.

  4. Bioavailability of PAHs in aluminum smelter affected sediments: evaluation through assessment of pore water concentrations and in vivo bioaccumulation.

    PubMed

    Ruus, Anders; Bøyum, Olav; Grung, Merete; Næs, Kristoffer

    2010-12-15

    Bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) from coal tar pitch polluted sediments was predicted by (1) a generic approach based on organic carbon-water partitioning and Gibbs linear free energy relationship (between K(OW) and K(OC)), and (2) measurements of freely dissolved concentrations of PAHs in the sediment pore water, using passive samplers and solid phase extraction. Results from these predictions were compared with those from in vivo bioaccumulation experiments using Nereis diversicolor (Polychaeta), Hinia reticulata (Gastropoda), and Nuculoma tenuis (Bivalvia). Measured sediment/water partition coefficients were higher than predicted by the generic approach. Furthermore, predicted biota-to-sediment accumulation factors (BSAFs) derived from measured pore water concentrations were more in agreement with the bioaccumulation observed for two of the three species. Discrepancies associated with the third species (N. tenuis) were likely a result of particles remaining in the intestine (as shown by microscopic evaluation). These results indicate the importance of conducting site-specific evaluations of pore water concentrations and/or bioaccumulation studies by direct measurements to accurately provide a basis for risk assessment and remediation plans. The importance of knowledge regarding specific characteristics of model organisms is emphasized. PMID:21077669

  5. Effects of dam construction on sediment phosphorus variation in a semi-enclosed bay of the Seto Inland Sea, Japan

    NASA Astrophysics Data System (ADS)

    Jin, Guangzhe; Onodera, Shin-ichi; Amano, Atsuko; Saito, Mitsuyo; Shimizu, Yuta; Satou, Takaharu

    2013-12-01

    This study investigated the effects of dam construction on sediment phosphorus concentrations in a semi-enclosed bay in western Japan. Long sediment core samples spanning over 100 years were collected from the bay, and their P fractions were analyzed. Sediment P concentrations and the P accumulation rate in an artificial lake increased after the construction of a coastal dam in 1959. The amount of P accumulated in the 60 years after the dam construction was ˜1.7 times that prior to the dam construction. Moreover, concentrations of mobile forms of P, primarily redox-sensitive P species, were higher in freshwater sediments above the dam than in saline sediments below the dam. The redox-sensitive forms of P in freshwater sediments increased sharply after the dam construction, from 100 to ˜900 μg/g, accompanied by a decrease in chloride (Cl-) concentrations to <2000 mg/l. In the artificial lake, the maximum values of total P (TP) and redox-sensitive P concentrations were ˜1200 μg/g and ˜900 μg/g at depths of 23 cm and 3 cm, respectively. Smaller peaks observed in the TP and redox-sensitive P concentration values likely corresponded to the recycled P released from sediments. The maximum values corresponded to hypereutrophic conditions that were caused by extensive discharges of sewage during the 1970s. The lake has been gradually recovering from these hypereutrophic conditions, as observed from the trophic state index. However, despite a substantial decrease in P loading after the 1980s, the lake still has a high trophic level. The presently high mobile P concentrations in surface sediments may lead to high-magnitude P releases with environmental changes in the future.

  6. Mercury concentrations in common carp (Cyprinus carpio) tissues, sediment and water from fish farm along the Karoun River in Iran

    PubMed Central

    Maktabi, Payvand; Javaheri Baboli, Mehran; Jafarnejadi, Ali Reza; Askary Sary, Abolfazl

    2015-01-01

    The Karoun River is major source of water for warm‌water fish culture industry in southwest of Iran. The aim of the present study was to investigate the distribution of mercury in tissues of marketable common carp and in bottom sediments of fish farms in Khouzestan province. This study was carried out on 45 fish farms that are located on the bank of the Karoun River in Khouzestan province, south-west Iran. Concentration of mercury (Hg) was determined using spectrophotometery in three tissues (muscles, liver and gills) of farmed common carp (Cyprinus carpio), water and bottom sediments of fish farms collected from three regions (North, center and south) of the Karoun River, in Khouzestan province, Iran. The concentrations of Hg in muscle tissue (2.71 mg kg-1 dry matter) of fish from the south were significantly higher (p < 0.05) than from the other two sites. In the center and south sampling zones, Hg concentration in muscle was found to be above the maximum tolerable values provided by Food and Drug Administration standards. The Hg concentration of fish farm sediment and water samples were ranged as 0.46 to 0.48 mg kg-1 dry matter and 3.10 to 4.11 μg Hg L-1, respectively. Finally, Hg concentrations at downstream site were higher than upstream site. PMID:26893811

  7. Occurrence and concentrations of benzotriazole UV stabilizers in marine organisms and sediments from the Ariake Sea, Japan.

    PubMed

    Nakata, Haruhiko; Murata, Sayaka; Filatreau, Julien

    2009-09-15

    The benzotriazole UV stabilizers, which are used in a variety of plastic products, were analyzed in marine organisms and sediments collected from the Ariake Sea, Japan. The UV stabilizers, such as UV-320, UV-326, UV-327, and UV-328 were detected in all of the samples analyzed, suggesting the production and use of these compounds in Japan. High concentrations of UV stabilizers were found in clams, oysters, and gastropods collected from the tidal flat at concentrations on the order of several hundreds of ng/g on a lipid weight (wt.) basis. The higher trophic species, such as hammerhead sharks and coastal birds, accumulated UV stabilizers, with mean concentrations of 190 ng/g and 74 ng/g (lipid wt.), respectively. These results indicate that benzotriazole UV stabilizers are persistent and bioaccumulative in the marine food-chains. The benzotriazole UV stabilizers were also detected in coastal and river sediments around the Ariake Sea, at concentrations in the range of 7.9-720 ng/g (dry weight basis). Significant correlations were found between concentrations of UV stabilizers and organic carbon content in sediments, implying adsorption of these compounds to organic matter. To our knowledge, this is the first report of ubiquitous contamination and bioaccumulation of benzotriazole UV stabilizers in the marine environment. PMID:19806721

  8. Exploring the uncertainty in attributing sediment contributions in fingerprinting studies due to uncertainty in determining element concentrations in source areas.

    NASA Astrophysics Data System (ADS)

    Gomez, Jose Alfonso; Owens, Phillip N.; Koiter, Alex J.; Lobb, David

    2016-04-01

    One of the major sources of uncertainty in attributing sediment sources in fingerprinting studies is the uncertainty in determining the concentrations of the elements used in the mixing model due to the variability of the concentrations of these elements in the source materials (e.g., Kraushaar et al., 2015). The uncertainty in determining the "true" concentration of a given element in each one of the source areas depends on several factors, among them the spatial variability of that element, the sampling procedure and sampling density. Researchers have limited control over these factors, and usually sampling density tends to be sparse, limited by time and the resources available. Monte Carlo analysis has been used regularly in fingerprinting studies to explore the probable solutions within the measured variability of the elements in the source areas, providing an appraisal of the probability of the different solutions (e.g., Collins et al., 2012). This problem can be considered analogous to the propagation of uncertainty in hydrologic models due to uncertainty in the determination of the values of the model parameters, and there are many examples of Monte Carlo analysis of this uncertainty (e.g., Freeze, 1980; Gómez et al., 2001). Some of these model analyses rely on the simulation of "virtual" situations that were calibrated from parameter values found in the literature, with the purpose of providing insight about the response of the model to different configurations of input parameters. This approach - evaluating the answer for a "virtual" problem whose solution could be known in advance - might be useful in evaluating the propagation of uncertainty in mixing models in sediment fingerprinting studies. In this communication, we present the preliminary results of an on-going study evaluating the effect of variability of element concentrations in source materials, sampling density, and the number of elements included in the mixing models. For this study a virtual

  9. Solute concentration effect on osmotic reflection coefficient.

    PubMed Central

    Adamski, R P; Anderson, J L

    1983-01-01

    A theory for the effect of concentration on osmotic reflection coefficient, correct to first order, was developed at the molecular level by considering the effect of solute-solute interactions on solute concentration and the fluid stress tensor within a solvent-filled pore. The solvent was modeled as a continuous fluid and potential energies between solute molecules and the pore wall were assumed to be pairwise additive. Although the theory is more general, calculations are presented only for excluded volume effects (hard-sphere for solute, hard-wall for pore). The relationship between the first-order concentration effect and the infinite dilution value of reflection coefficient appears to be geometry independent. The theory is discussed in light of experimental studies of osmotic flow that have recently appeared in the literature. PMID:6626681

  10. Vitamin B1 in marine sediments: pore water concentration gradient drives benthic flux with potential biological implications

    PubMed Central

    Monteverde, Danielle R.; Gómez-Consarnau, Laura; Cutter, Lynda; Chong, Lauren; Berelson, William; Sañudo-Wilhelmy, Sergio A.

    2015-01-01

    Vitamin B1, or thiamin, can limit primary productivity in marine environments, however the major marine environmental sources of this essential coenzyme remain largely unknown. Vitamin B1 can only be produced by organisms that possess its complete synthesis pathway, while other organisms meet their cellular B1 quota by scavenging the coenzyme from exogenous sources. Due to high bacterial cell density and diversity, marine sediments could represent some of the highest concentrations of putative B1 producers, yet these environments have received little attention as a possible source of B1 to the overlying water column. Here we report the first dissolved pore water profiles of B1 measured in cores collected in two consecutive years from Santa Monica Basin, CA. Vitamin B1 concentrations were fairly consistent between the two years ranging from 30 pM up to 770 pM. A consistent maximum at ~5 cm sediment depth covaried with dissolved concentrations of iron. Pore water concentrations were higher than water column levels and represented some of the highest known environmental concentrations of B1 measured to date, (over two times higher than maximum water column concentrations) suggesting increased rates of cellular production and release within the sediments. A one dimensional diffusion-transport model applied to the B1 profile was used to estimate a diffusive benthic flux of ~0.7 nmol m−2 d−1. This is an estimated flux across the sediment-water interface in a deep sea basin; if similar magnitude B-vitamin fluxes occur in shallow coastal waters, benthic input could prove to be a significant B1-source to the water column and may play an important role in supplying this organic growth factor to auxotrophic primary producers. PMID:26029181

  11. Effects of Drought-Induced Sediment Resuspension on Phosphorus Availability in Lake Powell, Utah

    NASA Astrophysics Data System (ADS)

    Wildman, R. A.; Miller, J.; Hering, J. G.

    2006-12-01

    The damming of a large river creates a lake ecosystem that differs substantially from that of the unaltered river upstream. Unlike a natural lake, this ecosystem is subject to large perturbations resulting from reservoir management decisions. For example, significant change in water surface elevation can lead to resuspension of lakebed sediments in the inflow region of the reservoir and may have important implications for the nutrient dynamics of a reservoir. Impounded by Glen Canyon Dam, Lake Powell is a large, long, and narrow reservoir on the mainstem of the Colorado River in Arizona and Utah. A severe drought in the Rocky Mountains has significantly decreased inflows to the lake. Constant yearly dam releases have led to a precipitous drop in the surface elevation and water storage of Lake Powell, including a record low in April 2005. The incoming Colorado River now cuts through the previously-undisturbed sediment delta. Thus, much of the incoming suspended load may come from the resuspension of deltaic sediments. Since these sediments likely contain phosphorus, this deltaic resuspension could be a major new source of nutrients to the oligotrophic, phosphorus-limited lake ecosystem. To quantify the resuspension and phosphorus concentration in the Lake Powell deltaic sediments, 70 and 100 cm cores were collected from the lakebed and shore sediments of Lake Powell March and May 2006. Cores were collected at six locations along the Colorado River delta in the inflow region of the lake and at three shore locations where the former delta sediments have been exposed. Water and suspended sediment samples were also collected at various depths at the same locations as the lakebed cores. Phosphorus concentration was measured in all samples. Sequential extractions were performed to assess the distribution of phosphorus in the solid phase. Ancillary sediment analyses included organic carbon and particle size measurements. The two sampling events captured different

  12. Environmental effects of dredging. New technique for sediment/organism equilibrium partitioning studies. Technical notes

    SciTech Connect

    McFarland, V.A.; Feldhaus, J.; Ace, L.N.; Brannon, J.M.

    1992-12-01

    Equilibrium partitioning (EqP) studies on bioaccumulation of organic chemicals in aquatic organisms typically require long-term exposures. In the case of highly hydrophobic neutral organic chemicals, such as polychiorinated biphenyls (PCBs), dioxins, and dibenzofurans, exposures of up to 6 months have been used (Pruell and others 1990). During long-term laboratory exposures, changes can occur in the condition of both organism and sediment. Sediments can be depleted of the bioavailable fraction of chemical, thereby reducing exposure. Nutrient quality and amount may decline and sublethal toxicity may occur, affecting the health of organisms and causing loss of lipids. Metabolic degradation of bioaccumulating chemicals may occur in long-term exposures, reducing bioaccumulation. Induction of metabolizing enzymes caused by the chemical under investigation or by other chemicals in the sediment may exacerbate this effect. Growth during the exposure period can dilute tissue concentrations causing reduced apparent bioaccumulation. Spawning and other seasonal changes also affect bioaccumulation (Lee and others 1989).

  13. Effectiveness of a sediment time critical removal action-PCB reduction in fish tissue, surface water, and sediment via wet excavation.

    PubMed

    Santini, Andrew D; King, Todd; Krawczyk, Keith; Kern, John W

    2015-01-01

    (federal, state, and local agencies and responsible parties) provided data demonstrating TCRA effectiveness. Before TCRA, surface sediment PCB concentration in instream and formerly inundated sediment combined was 83 mg/kg (with a maximum of 700 mg/kg). Instream sediments that are more representative of fish exposures had a pre-TCRA surface weighted average concentration (SWAC) of 27 mg/kg. The post-TCRA SWAC for instream and floodplain sediments combined was 0.26 mg/kg. Average surface water concentrations at the downstream end of the BMP were reduced from 0.11 µg/L pre-TCRA to 0.0025 µg/L post-TCRA. Tissue samples for adult carp fillets decreased from 4 mg/kg pre-TCRA to 0.26 mg/kg post-TCRA; whole body white suckers from 3 mg/kg pre-TCRA to 0.1 mg/kg post-TCRA; whole body channel catfish from 39 mg/kg-L pre-TCRA to 2.6 mg/kg-L post-TCRA. Concentrations of PCBs in 2 species of resident fish (carp and white suckers), caged channel catfish, surface water, and sediment were reduced by over 1 order of magnitude within 1 year of completion, substantively accelerating natural recovery processes. A slight increase in PCB concentration was observed in both whole body suckers and adult carp fillets in the second monitoring period post-TCRA; however, these concentrations are still near an order of magnitude less than pre-TCRA concentrations and appear to be currently stable or on a slight downward trend. PMID:25070026

  14. The sediment-contact test using the ostracod Heterocypris incongruens: Effect of fine sediments and determination of toxicity thresholds.

    PubMed

    Casado-Martinez, M Carmen; Burga-Pérez, Karen F; Bebon, Rebecca; Férard, Jean-François; Vermeirssen, Etienne L M; Werner, Inge

    2016-05-01

    The toxicity test using freshwater ostracods of the species Heterocypris incongruens is a sub-chronic static test that exposes individuals to whole sediments over a period of 6 d, the endpoints being mortality and growth. We tested the hypothesis that endpoints of the sediment bioassay using Heterocypris incongruens are affected by the presence of fine sediment particles by testing control sediment supplied with the commercial test kit with increasing proportions of kaolin clay as a proxy for fines. While mortality was not affected, the results showed that increasing the presence of clay reduced ostracod growth. Based on the variability in growth, a sublethal toxicity threshold of 35% is proposed to distinguish effects due to sediment properties from those due to toxicity. The relevance of this threshold was verified using data from toxicity tests of ambient sediment samples with low levels of contamination. PMID:26943743

  15. Harmful metals concentration in sediments and fishes of biologically important estuary, Bay of Bengal

    PubMed Central

    2013-01-01

    Study on the accumulation level of heavy metals was conducted on sediment and fishes from estuaries of Bay of Bengal. Heavy metals were determined by using Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) and the results were compared to permissible limits of WHO/USEPA. The accumulation patterns of Fe and Cd were found predominantly in all samples tested when correlated with other metals. It was found that the concentration of metals such as Cd (3.90 ± 0.25 μg/g), Cr (0.44 ± 0.05 μg/g), Ni (0.33 ± 0.01 μg/g), and Mn (1.1 ± 0.11 μg/g) were exceeding the permissible limit, whereas Fe, Co, Pb, and Zn were found within the limit of WHO/USEPA at station 1. In station 2, Cd (16.5 ± 0.4 μg/g), Mn (0.67 ± 0.11 μg/g), and Cr (0.80 ± 0.01 μg/g) were exceeding the permissible limit, whereas Fe, Co, Pb, Ni, and Zn were found within the limit. This study emphasizes that Cd and Mn levels in both stations, are far higher than the acceptable values set by WHO/USEPA and may therefore present human health hazards. It is therefore mandatory to carry out extensive research to evaluate the possible environmental risk factors in the vicinity of both estuaries with respect to heavy metals. PMID:24355110

  16. Pelagic molybdenum concentration anomalies and the impact of sediment resuspension on the molybdenum budget in two tidal systems of the North Sea

    NASA Astrophysics Data System (ADS)

    Kowalski, Nicole; Dellwig, Olaf; Beck, Melanie; Gräwe, Ulf; Neubert, Nadja; Nägler, Thomas F.; Badewien, Thomas H.; Brumsack, Hans-Jürgen; van Beusekom, Justus E. E.; Böttcher, Michael E.

    2013-10-01

    The seasonal dynamics of molybdenum (Mo) were studied in the water column of two tidal basins of the German Wadden Sea (Sylt-Rømø and Spiekeroog) between 2007 and 2011. In contrast to its conservative behaviour in the open ocean, both, losses of more than 50% of the usual concentration level of Mo in seawater and enrichments up to 20% were observed repeatedly in the water column of the study areas. During early summer, Mo removal by adsorption on algae-derived organic matter (e.g. after Phaeocystis blooms) is postulated to be a possible mechanism. Mo bound to organic aggregates is likely transferred to the surface sediment where microbial decomposition enriches Mo in the pore water. First δ98/95Mo data of the study area disclose residual Mo in the open water column being isotopically heavier than MOMo (Mean Ocean Molybdenum) during a negative Mo concentration anomaly, whereas suspended particulate matter shows distinctly lighter values. Based on field observations a Mo isotope enrichment factor of ɛ = -0.3‰ has been determined which was used to argue against sorption on metal oxide surfaces. It is suggested here that isotope fractionation is caused by biological activity and association to organic matter. Pelagic Mo concentration anomalies exceeding the theoretical salinity-based concentration level, on the other hand, cannot be explained by replenishment via North Sea waters alone and require a supply of excess Mo. Laboratory experiments with natural anoxic tidal flat sediments and modelled sediment displacement during storm events suggest fast and effective Mo release during the resuspension of anoxic sediments in oxic seawater as an important process for a recycling of sedimentary sulphide bound Mo into the water column.

  17. EFFECTS OF SUSPENDED SEDIMENTS ON PHOTOLYSIS RATES OF DISSOLVED POLLUTANTS

    EPA Science Inventory

    Data are presented concerning the effects of suspended sediments upon photolysis rates of dissolved ultraviolet (u.v.) absorbing pollutants. The malachite green leucocyanide actinometer was found to be a convenient and sensitive device for measurement of solar u.v. radiation (abo...

  18. Modelling the effects of Zostera noltei meadows on sediment dynamics: application to the Arcachon lagoon

    NASA Astrophysics Data System (ADS)

    Kombiadou, Katerina; Ganthy, Florian; Verney, Romaric; Plus, Martin; Sottolichio, Aldo

    2014-10-01

    A three-dimensional model has been modified to describe the complex interactions between hydrodynamics, sediment dynamics and biological parameters in the presence of Zostera noltei. The model treats seagrass leafs as flexible blades that bend under hydrodynamic forcing and alter the local momentum and turbulence fluxes and, therefore, the benthic shear conditions; these changes cause related changes to the mass balance at the boundary of the bed, in turn affecting the suspended matter in the column and ultimately primary productivity and the growth of the dwarf-grass. Modelling parameters related to the impact of Z. noltei to the local flow and to erosion and deposition rates were calibrated using flume experimental measurements; results from the calibration of the model are presented and discussed. The coupled model is applied in the Arcachon Bay, an area with high environmental significance and large abundance of dwarf-grass meadows. In the present paper, results from preliminary applications of the model are presented and discussed; the effectiveness of the coupled model is assessed comparing modelling results with available field measurements of suspended sediment concentrations and seagrass growth parameters. The model generally reproduces sediment dynamics and dwarf-grass seasonal growth in the domain efficiently. Investigations regarding the effects of the vegetation to the near-bed hydrodynamics and to the sediment suspension in the domain show that dwarf-grass meadows play an important part to velocity attenuation and to sediment stabilisation, with flow and suspended sediment concentrations damping, compared to an unvegetated state, to reach 35-50 and 65 %, respectively, at peak seagrass growth.

  19. Alaska Geochemical Database (AGDB)-Geochemical data for rock, sediment, soil, mineral, and concentrate sample media

    USGS Publications Warehouse

    Granitto, Matthew; Bailey, Elizabeth A.; Schmidt, Jeanine M.; Shew, Nora B.; Gamble, Bruce M.; Labay, Keith A.

    2011-01-01

    The Alaska Geochemical Database (AGDB) was created and designed to compile and integrate geochemical data from Alaska in order to facilitate geologic mapping, petrologic studies, mineral resource assessments, definition of geochemical baseline values and statistics, environmental impact assessments, and studies in medical geology. This Microsoft Access database serves as a data archive in support of present and future Alaskan geologic and geochemical projects, and contains data tables describing historical and new quantitative and qualitative geochemical analyses. The analytical results were determined by 85 laboratory and field analytical methods on 264,095 rock, sediment, soil, mineral and heavy-mineral concentrate samples. Most samples were collected by U.S. Geological Survey (USGS) personnel and analyzed in USGS laboratories or, under contracts, in commercial analytical laboratories. These data represent analyses of samples collected as part of various USGS programs and projects from 1962 to 2009. In addition, mineralogical data from 18,138 nonmagnetic heavy mineral concentrate samples are included in this database. The AGDB includes historical geochemical data originally archived in the USGS Rock Analysis Storage System (RASS) database, used from the mid-1960s through the late 1980s and the USGS PLUTO database used from the mid-1970s through the mid-1990s. All of these data are currently maintained in the Oracle-based National Geochemical Database (NGDB). Retrievals from the NGDB were used to generate most of the AGDB data set. These data were checked for accuracy regarding sample location, sample media type, and analytical methods used. This arduous process of reviewing, verifying and, where necessary, editing all USGS geochemical data resulted in a significantly improved Alaska geochemical dataset. USGS data that were not previously in the NGDB because the data predate the earliest USGS geochemical databases, or were once excluded for programmatic reasons

  20. A dynamic sediment model based on satellite-measured concentration of the surface suspended matter in the East China Sea

    NASA Astrophysics Data System (ADS)

    Mao, Zhihua; Pan, Delu; Tang, Charles L.; Tao, Bangyi; Chen, Jianyu; Bai, Yan; Chen, Peng; He, Xianqiang; Hao, Zengzhou; Huang, Haiqing; Zhu, Qiankun

    2016-04-01

    The concentration of total suspended matter (TSM) at the sea surface is derived from satellite data using a complex proxy TSM model in East China Sea from 1997 to 2008. The structure of the mean TSM image is similar to that of the topography, indicating that the distribution of the surface concentration is strongly related to the water depth. A dynamic sediment model (DSM) is constructed to relate the TSM concentration at the sea surface with suspended sediment at the benthic boundary layer, the Rouse number, and the water depth. The DSM model is improved through iteration with a convergence identified by the mean relative difference between two adjacent bottom TSM images which becomes smaller with the more iterations and the value is less than 1% after 50 iterations. The performance of the DSM model is validated by satellite-measured concentration with a mean relative error of 5.2% for the monthly mean images. The DSM model is used to deduce the bottom TSM concentration at the benthic boundary layer and the distribution of the Rouse number. The spatial distribution of the sea surface TSM concentration is determined predominately by both the bottom suspended sediment concentration and water depth. The temporal variation of the sea surface concentration mainly depends upon the Rouse number in the water column. Our result shows that the discharge of the Changjiang River can change the distribution of the Rouse number to form a band-shaped region in the Changjiang Estuary. The DSM model provides a framework for understanding some of the mechanisms of the formation and variation of the primary TSM plume and the secondary plume in the ECS. The primary TSM plume corresponds approximately to the region with depth shallower than 20 m and the secondary plume corresponds to the region with depths between 20 and 50 m.

  1. Effects of Aggregation on Blood Sedimentation and Conductivity

    PubMed Central

    Zhbanov, Alexander; Yang, Sung

    2015-01-01

    The erythrocyte sedimentation rate (ESR) test has been used for over a century. The Westergren method is routinely used in a variety of clinics. However, the mechanism of erythrocyte sedimentation remains unclear, and the 60 min required for the test seems excessive. We investigated the effects of cell aggregation during blood sedimentation and electrical conductivity at different hematocrits. A sample of blood was drop cast into a small chamber with two planar electrodes placed on the bottom. The measured blood conductivity increased slightly during the first minute and decreased thereafter. We explored various methods of enhancing or retarding the erythrocyte aggregation. Using experimental measurements and theoretical calculations, we show that the initial increase in blood conductivity was indeed caused by aggregation, while the subsequent decrease in conductivity resulted from the deposition of erythrocytes. We present a method for calculating blood conductivity based on effective medium theory. Erythrocytes are modeled as conducting spheroids surrounded by a thin insulating membrane. A digital camera was used to investigate the erythrocyte sedimentation behavior and the distribution of the cell volume fraction in a capillary tube. Experimental observations and theoretical estimations of the settling velocity are provided. We experimentally demonstrate that the disaggregated cells settle much slower than the aggregated cells. We show that our method of measuring the electrical conductivity credibly reflected the ESR. The method was very sensitive to the initial stage of aggregation and sedimentation, while the sedimentation curve for the Westergren ESR test has a very mild slope in the initial time. We tested our method for rapid estimation of the Westergren ESR. We show a correlation between our method of measuring changes in blood conductivity and standard Westergren ESR method. In the future, our method could be examined as a potential means of accelerating

  2. Polychlorinated dibenzo-p-dioxin and dibenzofuran concentration profiles in sediment and fish tissue of the Willamette Basin, Oregon

    USGS Publications Warehouse

    Bonn, B.A.

    1998-01-01

    Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) are highly hydrophobic compounds that have been implicated as carcinogens and, more recently, as estrogen disrupters. An occurrence and distribution study of these compounds in the Willamette Basin, Oregon, was conducted by the U.S. Geological Survey as part of the National Water-Quality Assessment Program. Bed sediment was collected from 22 sites; fish tissue was collected from eight sites. PCDD/F were found to be ubiquitous in Willamette Basin sediment. A distinct homolog profile, dominated by octachlorodibenzo-p-dioxin, was observed in sediment throughout the basin. The PCDD homolog profile was consistent at all sites, regardless of total PCDD/F concentration, presence of point sources, subbasin size, geographic location or land use. Principal components analysis revealed a gradient among the homolog profiles that showed increasing dominance of highly chlorinated congeners where human and industrial activity increased. Tissue and bed sediment obtained from the same site did not have similar PCDD/F concentrations or homolog profiles. Fish tissue showed enrichment in less chlorinated congeners and congeners with chlorine substitutions in the 2, 3, 7 and 8 positions.

  3. Toxic Elements in Aquatic Sediments: Distinguishing Natural Variability from Anthropogenic Effects

    PubMed Central

    DeLaune, Ronald D.; Tan, MeiHuey; Reams, Margaret; Laws, Edward

    2016-01-01

    Regressions of aluminum against potentially toxic elements in the sediments of freshwater aquatic systems in Louisiana were used to distinguish natural variability from anthropogenic pollution when elemental concentrations exceeded screening effects levels. The data were analyzed using geometric mean model II regression methods to minimize, insofar as possible, bias that would have resulted from the use of model I regression. Most cadmium concentrations exceeded the threshold effects level, but there was no evidence of an anthropogenic impact. In Bayou Trepagnier, high concentrations of Cr, Cu, Pb, Ni, and Zn appeared to reflect anthropogenic pollution from a petrochemical facility. In Capitol Lake, high Pb concentrations were clearly associated with anthropogenic impacts, presumably from street runoff. Concentrations of potentially toxic elements varied naturally by as much as two orders of magnitude; hence it was important to filter out natural variability in order to identify anthropogenic effects. The aluminum content of the sediment accounted for more than 50% of natural variability in most cases. Because model I regression systematically under-estimates the magnitude of the slope of the regression line when the independent variable is not under the control of the investigator, use of model II regression methods in this application is necessary to facilitate hypothesis testing and to avoid incorrectly associating naturally high elemental concentrations with human impacts. PMID:27330231

  4. Oil effect in freshly spiked marine sediment on Vibrio fischeri, Corophium volutator, and Echinocardium cordatum.

    PubMed

    Brils, Jos M; Huwer, Sherri L; Kater, Belinda J; Schout, Peter G; Harmsen, Joop; Delvigne, Gerard A L; Scholten, Martin C Th

    2002-10-01

    The purpose of this study was to provide data to be used in The Netherlands for development of ecotoxicologically based quality criteria for oil-contaminated sediments and dredged material. In addition, the relation of toxicity to specific oil boiling-point fraction ranges was explored. Natural marine sediment, with a moisture, organic carbon, and silt content of approximately 80, 1.8, and 33% of the dry weight, respectively, was artificially spiked using a spiking method developed in this project. Aliquots of one part of the sediment were spiked to several concentrations of Gulf distillate marine grade A (DMA) gasoil (containing 64% C10-19) and aliquots of the other part to several concentrations of Gulf high viscosity grade 46 (HV46) hydraulic oil (containing 99.2% C19-40). Thus, for each individual oil type, a concentration series was created. Vibrio fischeri (endpoint: bioluminescence inhibition), Corophium volutator (endpoint:mortality), and Echinocardium cordatum (endpoint:mortality) were exposed to these spiked sediments for 10 min, 10 d and 14 d, respectively. Based on the test results, the effective concentration on 50% of the test animals was statistically estimated. For DMA gasoil and HV46 hydraulic oil, respectively, the effective concentrations were 43.7 and 2,682 mg/kg dry weight for V. fischeri, 100 and 9,138 mg/kg dry weight for C. volutator, 190, and 1064 mg/kg dry weight for E. cordatum. This study shows that the toxicity is strongly correlated with the lower boiling-point fractions and especially to those within the C10-C19 range. PMID:12371504

  5. A comparison of measured and modeled suspended sediment concentration profiles during different types of meteorological events on the inner-shelf of Long Bay, South Carolina

    NASA Astrophysics Data System (ADS)

    Wren, P. A.; Ma, Y.

    2010-12-01

    An instrumented quadrapod was deployed on the inner-shelf of Long Bay, South Carolina at a depth of approximately 7 meters from July 2008 - December 2009. A multi-frequency Acoustic Backscatter Sensor (ABS) and a pulse-coherent Acoustic Doppler Current Profiler (PC-ADCP) were used to collect co-located long-term measurements of suspended sediment concentrations and high-resolution velocity profiles throughout the bottom boundary layer. To invert the acoustic backscatter voltage collected by the ABS, a semi-empirical backscattering theory (Thorne and Hanes, 2002) was first verified with sediment chamber measurements using local sediments. The verified theory was then employed to determine sediment grain size and suspended sediment concentrations. Additionally, to complement the field observations, two different 1-D bottom boundary layer models (Styles and Glenn, 2000 and Wiberg and Smith, 1983) were applied to estimate the bed shear stress, velocity and suspended sediment concentration profiles. Although both models are based on boundary layer theory (Smith,1977; Grant and Madsen, 1979), and require as inputs of wave and current velocities as well as characteristics of sea-bed sediment, they are distinct in some practical applications such as eddy-viscosity profile, ripple dimension estimation, model gridding, etc. Recorded waves, currents, and acoustic backscatter data revealed that nineteen sediment transport events occurred during the eighteen month study period, which resulted in an order of magnitude range of suspended sediment concentrations. Comparisons of sediment concentration profiles between the two 1-D models and the field measurements were conducted during several different types of sediment transport events. The events that were used for the comparisons included two types of frequently occurring frontal systems, as well a direct hit from Tropical Storm Hannah. During the selected events near-bottom orbital velocities ranged from 20 - 60 cm s-1 and

  6. Surface Sediment Effects on Teleseismic P Wave Ground Displacement

    NASA Astrophysics Data System (ADS)

    Zhou, Y.; Nolet, G.; Dahlen, F. A.

    2001-12-01

    Large scatter in short-period body-wave amplitude measurements over short distances have been widely observed. "Station corrections" are essential when amplitude data are applied to determine event magnitude, and, occasionally, to explore deeper subsurface structures. In this paper, we investigated the effects of surface sediments on teleseismic P wave displacement amplitude assuming layered crust structures. Local scattering effects are ignored since we are interested in the teleseismic waves with dominant frequency well below 1 Hz. Generally, displacements are amplified as seismic waves propagate into a low-impedance sediment layer. As the wavefield interacts with a surface sediment layer, P wave reverberations de-amplify the ground displacement recorded by seismic sensors at the surface. The de-amplification effect is dependent on the period of the seismic wave. Numerical calculations show when the period of the seismic wave is much longer than P wave 2-way travel time in the surface sediment layer, it doesn't "feel" the existance of the sediment layer, which leaves amplitudes intact except for about a factor of 2 amplification effect caused by the free-surface. At shorter period, the amplification effect is approximately linearly-dependent on the period of seismic waves. When the period of seismic wave is short and within a couple of times of the P wave 2-way travel time in the sediment, the amplification effects varies greatly over a small range of seismic wave period. It indicates that surface displacement amplitude of high-frequency P wave could vary laterally up to an order of magnitude where P wave velocity in the surface weathering layer is low (less than few hundred meters per second) and lateral variations of the relative impedance are extremely large. A 7-layer 2x2 degree global crust model, {Crust2.0} (Laske et al) is used to estimate frequency-dependent station corrections in the continents and the stable period range of teleseismic P waves for

  7. Effects of sediment physical properties on the phosphorus release in aquatic environment

    NASA Astrophysics Data System (ADS)

    Zhu, HongWei; Wang, DaoZeng; Cheng, PengDa; Fan, JingYu; Zhong, BaoChang

    2015-02-01

    Particle size, porosity, and the initial phosphorus concentration in sediments are the main factors affecting phosphorus release flux through the sediment-water interface. Sediments can be physically divided to muddy and sandy matters, and the adsorption-desorption capacity of sediment with phosphorus depends on particle size. According to phosphorus adsorption-desorption experiments, phosphorus sorption capacity of the sediment decreases with the increase of particle dimension. But among the size-similar particles, sediment with a bigger particle size has the larger initial phosphorus release rate. In terms of muddy and sandy sediments, there are inversely proportional relationships between the release rate and the flux. Due to the contact of surface sediment and the overlying water, the release flux from the sediment is either from direct desorption of surface sediment layer or from the diffusion of pore water in the sediment layer, which is mainly determined by sediment particle size and porosity. Generally, static phosphorus release process may include two stages: the first is the initial release. As for coarse particles, phosphorus is desorbed from surface sediment. And for fine particles, phosphorus concentration in water often decreases, mainly from pore water by the molecular diffusion. During the second stage, pore water flows faster in coarse sediment, and phosphorus is easy to desorb from the surface of the particles as diffusion dominates. For the smaller liquid-solid ratio of fine particles and the larger amount of phosphorus adsorption, the release flux from pore water due to diffusion is very small with longer sorption duration.

  8. Effect of check dams on runoff, sediment yield and retention on small semi-arid watersheds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Erosion dynamics in semi-arid environments are defined by high magnitude, low frequency rainfalls that produce runoff with high sediment concentration. Check dams are widely used in this environment as sedimentation mitigation technique, however their impact on overall watershed sediment balance is ...

  9. A Comparison of Turbidity-Based and Streamflow-Based Estimates of Suspended-Sediment Concentrations in Three Chesapeake Bay Tributaries

    USGS Publications Warehouse

    Jastram, John D.; Moyer, Douglas; Hyer, Kenneth

    2009-01-01

    Fluvial transport of sediment into the Chesapeake Bay estuary is a persistent water-quality issue with major implications for the overall health of the bay ecosystem. Accurately and precisely estimating the suspended-sediment concentrations (SSC) and loads that are delivered to the bay, however, remains challenging. Although manual sampling of SSC produces an accurate series of point-in-time measurements, robust extrapolation to unmeasured periods (especially highflow periods) has proven to be difficult. Sediment concentrations typically have been estimated using regression relations between individual SSC values and associated streamflow values; however, suspended-sediment transport during storm events is extremely variable, and it is often difficult to relate a unique SSC to a given streamflow. With this limitation for estimating SSC, innovative approaches for generating detailed records of suspended-sediment transport are needed. One effective method for improved suspended-sediment determination involves the continuous monitoring of turbidity as a surrogate for SSC. Turbidity measurements are theoretically well correlated to SSC because turbidity represents a measure of water clarity that is directly influenced by suspended sediments; thus, turbidity-based estimation models typically are effective tools for generating SSC data. The U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency Chesapeake Bay Program and Virginia Department of Environmental Quality, initiated continuous turbidity monitoring on three major tributaries of the bay - the James, Rappahannock, and North Fork Shenandoah Rivers - to evaluate the use of turbidity as a sediment surrogate in rivers that deliver sediment to the bay. Results of this surrogate approach were compared to the traditionally applied streamflow-based approach for estimating SSC. Additionally, evaluation and comparison of these two approaches were conducted for nutrient estimations. Results

  10. Comparability of suspended-sediment concentration and total suspended-solids data for two sites on the L'Anguille River, Arkansas, 2001 to 2003

    USGS Publications Warehouse

    Galloway, Joel M.; Evans, Dennis A.; Green, W. Reed

    2005-01-01

    Suspended-sediment concentration and total suspended solids data collected with automatic pumping samplers at the L'Anguille River near Colt and the L'Anguille River at Palestine, Arkansas, August 2001 to October 2003 were compared using ordinary least squares regression analyses to determine the relation between the two datasets for each of the two sites. The purpose of this report is to describe the suspended-sediment concentration and total suspended-solids data and examine the comparability of the two datasets for each site. Suspended-sediment concentration and total suspended solids data for the L'Anguille River varied spatially and temporally from August 2001 to October 2003. The site at the L'Anguille River at Palestine represents a larger portion of the L'Anguille River Basin than the site near Colt, and generally had higher median suspended-sediment concentration and total suspended solids and greater ranges in values. The differences between suspended-sediment concentration and total suspended solids data for the L'Anguille River near Colt appeared inversely related to streamflow and not related to time. The relation between suspended-sediment concentration and total suspended solids at the L'Anguille River at Palestine was more variable than at Colt and did not appear to have a relation with flow or time. The relation between suspended-sediment concentration and total suspended solids for the L'Anguille River near Colt shows that total suspended solids increased proportionally as suspended-sediment concentration increased. However, the relation between suspended-sediment concentration and total suspended solids for the L'Anguille River at Palestine showed total suspended solids increased less proportionally as suspended-sediment concentration increased compared to the L'Anguille River near Colt. Differences between the two analytical methods may partially explain differences between the suspended-sediment concentration and total suspended solids data at