Science.gov

Sample records for polvo sedimentable asma

  1. Polvo en la Región de los Troyanos

    NASA Astrophysics Data System (ADS)

    Gilhutton, R.; Brunini, A.; Coldwell, G.

    La posible existencia de un anillo de polvo en la resonancia 1:1 con Júpiter formado por partículas provenientes de colisiones de asteroides fue propuesta por Liou and Zook (Icarus 113, 403, 1995) y estudiada extensamente por Vieira Martins and Gomes (VIII Reunión Regional Latinoamericana de Astronomía, Montevideo,1995). Si bien las partículas quedarían atrapadas sólo por períodos de algunos miles de años, el proceso colisional continuo en el cinturón de asteroides mantendría constante la densidad, presentándose una mayor concentración en la región de los troyanos. En el presente trabajo se presentan resultados preliminares sobre observaciones polarimétricas realizadas desde CASLEO de la región de L5 que confirmarían la existencia y variaciones de densidad en el anillo de polvo.

  2. Dinámica y crecimiento de los granos de polvo en la nebulosa protoplanetaria

    NASA Astrophysics Data System (ADS)

    de La Fuente Marcos, Carlos

    2001-06-01

    En el escenario estándar de la formación planetaria, los planetesimales (cuerpos de tamaño kilométrico) crecen a partir de granos de polvo, similares a los interestelares, embebidos en un disco gaseoso denominado nebulosa protoplanetaria. Durante esta etapa, los movimientos del gas pueden tener gran influencia en la dinámica y el crecimiento de los granos de polvo, dado que el flujo kepleriano del gas frena el movimiento de los mismos haciendo que caigan hacia el Sol, y la turbulencia inhibe la inestabilidad gravitacional de la capa de polvo. Aunque se acepta que los planetesimales fueron los elementos constituyentes de los planetas, todavía se desconoce cómo se produjo la formación de los mismos. Por esta razón, en los estudios más recientes, existe un renovado interés por comprender mejor la evolución de la capa de polvo inmersa en el disco gaseoso de la Nebulosa. El gas que fluye en el disco puede engendrar estructuras carentes de simetría axial, como por ejemplo ondas espirales y vórtices, a partir de gran variedad de mecanismos de excitación e inestabilidad. En 1995, Barge y Sommeria pusieron de manifiesto que la existencia de vórtices gaseosos persistentes en la nebulosa solar tendría importantes consecuencias sobre la formación de los planetesimales y el posterior crecimiento de los planetas gigantes. La investigación desarrollada en esta Tesis analiza la relación entre el polvo y el gas debida al acoplamiento por fricción dinámica entre ambos; en concreto, se estudia el efecto del flujo medio del gas sobre la dinámica de las partículas de polvo. El primer objetivo es investigar en profundidad los procesos de captura y crecimiento de los granos de polvo dentro de un vórtice y su posible relevancia en cuanto a la formación de los planetesimales. El segundo objetivo es la exploración de los efectos de ondas espirales propagándose en el disco gaseoso sobre la dinámica y el crecimiento de las partículas. La presencia de líneas de

  3. Roles of the outer membrane protein AsmA of Salmonella enterica in the control of marRAB expression and invasion of epithelial cells.

    PubMed

    Prieto, Ana I; Hernández, Sara B; Cota, Ignacio; Pucciarelli, M Graciela; Orlov, Yuri; Ramos-Morales, Francisco; García-del Portillo, Francisco; Casadesús, Josep

    2009-06-01

    A genetic screen for suppressors of bile sensitivity in DNA adenine methylase (dam) mutants of Salmonella enterica serovar Typhimurium yielded insertions in an uncharacterized locus homologous to the Escherichia coli asmA gene. Disruption of asmA suppressed bile sensitivity also in phoP and wec mutants of S. enterica and increased the MIC of sodium deoxycholate for the parental strain ATCC 14028. Increased levels of marA mRNA were found in asmA, asmA dam, asmA phoP, and asmA wec strains of S. enterica, suggesting that lack of AsmA activates expression of the marRAB operon. Hence, asmA mutations may enhance bile resistance by inducing gene expression changes in the marRAB-controlled Mar regulon. In silico analysis of AsmA structure predicted the existence of one transmembrane domain. Biochemical analysis of subcellular fractions revealed that the asmA gene of S. enterica encodes a protein of approximately 70 kDa located in the outer membrane. Because AsmA is unrelated to known transport and/or efflux systems, we propose that activation of marRAB in asmA mutants may be a consequence of envelope reorganization. Competitive infection of BALB/c mice with asmA(+) and asmA isogenic strains indicated that lack of AsmA attenuates Salmonella virulence by the oral route but not by the intraperitoneal route. Furthermore, asmA mutants showed a reduced ability to invade epithelial cells in vitro.

  4. Roles of the Outer Membrane Protein AsmA of Salmonella enterica in the Control of marRAB Expression and Invasion of Epithelial Cells▿

    PubMed Central

    Prieto, Ana I.; Hernández, Sara B.; Cota, Ignacio; Pucciarelli, M. Graciela; Orlov, Yuri; Ramos-Morales, Francisco; García-del Portillo, Francisco; Casadesús, Josep

    2009-01-01

    A genetic screen for suppressors of bile sensitivity in DNA adenine methylase (dam) mutants of Salmonella enterica serovar Typhimurium yielded insertions in an uncharacterized locus homologous to the Escherichia coli asmA gene. Disruption of asmA suppressed bile sensitivity also in phoP and wec mutants of S. enterica and increased the MIC of sodium deoxycholate for the parental strain ATCC 14028. Increased levels of marA mRNA were found in asmA, asmA dam, asmA phoP, and asmA wec strains of S. enterica, suggesting that lack of AsmA activates expression of the marRAB operon. Hence, asmA mutations may enhance bile resistance by inducing gene expression changes in the marRAB-controlled Mar regulon. In silico analysis of AsmA structure predicted the existence of one transmembrane domain. Biochemical analysis of subcellular fractions revealed that the asmA gene of S. enterica encodes a protein of ∼70 kDa located in the outer membrane. Because AsmA is unrelated to known transport and/or efflux systems, we propose that activation of marRAB in asmA mutants may be a consequence of envelope reorganization. Competitive infection of BALB/c mice with asmA+ and asmA isogenic strains indicated that lack of AsmA attenuates Salmonella virulence by the oral route but not by the intraperitoneal route. Furthermore, asmA mutants showed a reduced ability to invade epithelial cells in vitro. PMID:19346309

  5. Formación estelar en NGC 6357: viendo a través del polvo con Gemini

    NASA Astrophysics Data System (ADS)

    Bosch, G.; Morrell, N.; Barbá, R.

    Presentamos aquí los primeros resultados de fotometría JHKs obtenidos con Flamingos I en el telescopio Gemini Sur. El mosaico comprendido por tres posiciones adyacentes tomadas a lo largo de varios semestres nos permite caracterizar la población estelar en la zona que presenta una interacción más importante entre las estrellas masivas y la nube molecular que les dió origen. Los diagramas color-magnitud nos permiten identificar numerosas fuentes con exceso infrarrojo, la mayoría de ellas imposible de detectarse en el rango óptico debido a la fuerte absorción del polvo presente en la región. Es altamente probable que la mayoría de estas fuentes con exceso sean protoestrellas, aunque es necesario realizar espectroscopía infrarroja de las mismas para confirmar su naturaleza.

  6. Lack of Clinical Relevance of ANA and ASMA Positivity in Patients with Liver Transplantation without a History of Autoimmune Diseases.

    PubMed

    Pellegrini, Lucienne; Parrilli, Gianpaolo; Santonicola, Antonella; Cinquanta, Luigi; Caputo, Cesare; Ciacci, Carolina; Zingone, Fabiana

    2017-01-01

    The relevance of isolated autoimmunity elevation in orthotopic liver transplantation (OLT) patients is unknown. Our aim was to analyse how serum autoantibodies change in time and to evaluate their clinical relevance in OLT patients. Patients were invited to provide samples to evaluate ANA, AMA, ASMA, and LKM at the time of enrolment (T0), after 6 months (T6), and after 12 months (T12). We included 114 patients in the study (76% males, median age 62.5 years), finding isolated elevation of at least one serum antibody in up to 80% of them. We described fluctuating positive autoantibodies in the one year of observation, with only 45.6% of patients positive for ANA and less than 2% positive for ASMA, at all three times. Isolated elevation of tissue antibodies was not related to gender, age, HCC at transplant, early rejection, cause of transplantation, immunotherapy taken, and age at the time of the study. We did not detect a higher prevalence of positive autoimmunity in patients with signs of liver injury. ANA and ASMA evaluation in patients with liver transplantation and no history of autoimmune disease has no clinical relevance, since it varies in time and is not related to any risk factors or liver injury. Routine autoimmunity evaluation should be avoided.

  7. Lack of Clinical Relevance of ANA and ASMA Positivity in Patients with Liver Transplantation without a History of Autoimmune Diseases

    PubMed Central

    Pellegrini, Lucienne; Parrilli, Gianpaolo; Santonicola, Antonella; Cinquanta, Luigi; Caputo, Cesare

    2017-01-01

    The relevance of isolated autoimmunity elevation in orthotopic liver transplantation (OLT) patients is unknown. Our aim was to analyse how serum autoantibodies change in time and to evaluate their clinical relevance in OLT patients. Patients were invited to provide samples to evaluate ANA, AMA, ASMA, and LKM at the time of enrolment (T0), after 6 months (T6), and after 12 months (T12). We included 114 patients in the study (76% males, median age 62.5 years), finding isolated elevation of at least one serum antibody in up to 80% of them. We described fluctuating positive autoantibodies in the one year of observation, with only 45.6% of patients positive for ANA and less than 2% positive for ASMA, at all three times. Isolated elevation of tissue antibodies was not related to gender, age, HCC at transplant, early rejection, cause of transplantation, immunotherapy taken, and age at the time of the study. We did not detect a higher prevalence of positive autoimmunity in patients with signs of liver injury. ANA and ASMA evaluation in patients with liver transplantation and no history of autoimmune disease has no clinical relevance, since it varies in time and is not related to any risk factors or liver injury. Routine autoimmunity evaluation should be avoided. PMID:28337446

  8. Synthesis and characterization of fac-Re(CO)3-aspartic-N-monoacetic acid, a structural analogue of a potential new renal tracer, fac-(99m)Tc(CO)3(ASMA).

    PubMed

    Klenc, Jeffrey; Lipowska, Malgorzata; Taylor, Andrew T; Marzilli, Luigi G

    2012-09-01

    The reaction of an aminopolycarboxylate ligand, aspartic-N-monoacetic acid (ASMA), with [Re(CO)3(H2O)3](+) was examined. The tridentate coordination of ASMA to this Re(I) tricarbonyl precursor yielded fac-Re(CO)3(ASMA) as a mixture of diastereomers. The chemistry is analogous to that of the Tc(I) tricarbonyl complex, which yields fac-(99m)Tc(CO)3(ASMA) under similar conditions. The formation, structure, and isomerization of fac-Re(CO)3(ASMA) products were characterized by HPLC, (1)H NMR spectroscopy, and X-ray crystallography. The two major fac-Re(CO)3(ASMA) diastereomeric products each have a linear ONO coordination mode with two adjacent five-membered chelate rings, but they differ in the endo or exo orientation of the uncoordinated acetate group, in agreement with expectations based on previous studies. Conditions have been identified for the expedient isomerization of fac-Re(CO)3(ASMA) to a mixture consisting primarily of one major product. Because different isomeric species typically have different pharmacokinetic characteristics, these conditions may provide for the practical isolation of a single (99m)Tc(CO)3(ASMA) species, thus allowing the isolation of the isomer that has optimal imaging and pharmacokinetic characteristics. This information will aid in the design of future (99m)Tc radiopharmaceuticals.

  9. Análisis del espectro infrarrojo del polvo interestelar asociado con cúmulos globulares y de su evolución temporal

    NASA Astrophysics Data System (ADS)

    Pellizza, L. J.; Forte, J. C.; Carpintero, D.

    El trabajo que se presenta investiga la dinámica de las partículas de polvo interestelar eyectadas por estrellas gigantes rojas en un cúmulo globular utilizando simulaciones numéricas de su interacción con el campo gravitatorio y con la radiación electromagnética de las estrellas. Se pretende con ello determinar la distribución espacial de ese material como una función del tiempo en un sistema similar a NGC 104 (47 Tuc). A partir de la distribución espacial resultante se obtuvo el espectro infrarrojo integrado el cual sugiere que el máximo contraste con la radiación estelar ocurre en longitudes de onda cercanas a 300 μm y que decrece rápidamente hacia longitudes de onda menores, en las que suelen realizarse las observaciones.

  10. Coastal sedimentation

    NASA Technical Reports Server (NTRS)

    Schubel, J. R.

    1980-01-01

    Several important coastal sedimentation problems are identified. Application of existing or anticipated remote sensing techniques to examine these problems is considered. Specifically, coastal fine particle sediment systems, floods and hy hurricanes and sedimentation f of coastal systems, routes and rates of sediment transport on continental shelves, and dredging and dredged material disposal are discussed.

  11. [Effects of hydroxycamptothecin on TGFb1, a-SMA and collagen I expression in rat hepatic satellite cells].

    PubMed

    Hu, Guo-xin; Wan, Zan-yan; Shao, Jia-liang; Zhang, Yi; Zhang, Lun-li; Gong, Zuo-jiong

    2012-06-01

    To investigate the molecular mechanism of hydroxycamptothecin (HCPT)-mediated anti-hepatic fibrosis by evaluting its effects on expression of tumor growth factor-beta 1 (TGFb1), alpha-smooth muscle actin (a-SMA) and collagen I (Col I) in hepatic satellite cells (HSCs). Cultured HSCs were treated with different concentrations of HCPT: low-dose group, 0.25 mg/L; middle-dose group, 0.5 mg/L; high-dose group, 0.75 mg/L; and control group, 0 mg/L. Cell proliferation was assessed by the MTT assay. The mRNA expressions of TGFb1, a-SMA and Col I were determined by reverse transcription-polymerase chain reaction. The protein expressions of TGFb1 and a-SMA were detected by Western blot. The content of Col I in the cultured HSCs' supernatant was measured by enzyme-linked immunosorbent assay. The MTT absorbance values of the low-dose group (0.631+/-0.074), middle-dose group (0.469+/- 0.012) and high-dose group (0.204+/- 0.001) were significantly lower than that of the control group (0.793+/-0.098; F = 82.86, P less than 0.01). Compared with the control group, the HCPT-treated groups showed significantly down-regulated gene expressions of TGFb1 (control: 0.716+/-0.064 vs. low: 0.611+/-0.040, middle: 0.510+/-0.014, high: 0.403+/-0.026), a-SMA (control: 0.696+/-0.075 vs. low: 0.579+/-0.037, middle: 0.470+/-0.024, high: 0.299+/-0.017), and Col I (control: 1.019+/-0.056 vs. low: 0.835+/-0.022, middle: 0.696+/-0.055, high: 0.322+/-0.104) (all, P less than 0.01). Meanwhile, HCPT-treated HSCs showed significantly reduced protein expressions of TGFb1 (control: 0.872+/-0.053 vs. low: 0.654+/-0.047, middle: 0.545+/-0.042, high: 0.436+/-0.039) and a-SMA (control: 0.858+/-0.050 vs. low: 0.620+/-0.045, middle: 0.525+/-0.042, high: 0.434+/-0.052) (all, P less than 0.01). The Col I levels secreted by HSCs were significantly lower in the HCPT-treated groups (low: 168.367+/-16.453 ng/ml; middle: 141.284+/-11.731 ng/ml; high: 132.910+/-10.048 ng/ml) than in the control group (188.733 +/-18

  12. Contaminated Sediment

    EPA Pesticide Factsheets

    Contaminated sediments are a significant problem in the Great Lakes basin. Persistent high concentrations of contaminants in the bottom sediments of rivers and harbors pose risks to aquatic organisms, wildlife, and humans.

  13. Aquatic Sediments.

    ERIC Educational Resources Information Center

    Sanville, W. D.; And Others

    1978-01-01

    Presents a literature review of aquatic sediments and its effect upon water quality, covering publications of 1976-77. This review includes: (1) sediment water interchange; (2) chemical and physical characterization; and (3) heavy water in sediments. A list of 129 references is also presented. (HM)

  14. Sediment Toxicity Testing

    EPA Science Inventory

    Sediment toxicity testing has become a fundamental component of regulatory frameworks for assessing the risks posed by contaminated sediments and for development of chemical sediment quality guidelines. Over the past two decades, sediment toxicity testing methods have advanced co...

  15. [Allergen immunotherapy: Mechanisms of action, and therapeutic and socioeconomic impact Consensus of the Asociación Colombiana de Alergia, Asma e Imunología].

    PubMed

    Sánchez, Jorge; Cardona, Ricardo; Caraballo, Luis; Serrano, Carlos; Ramírez, Ruth; Díez, Susana; García, Elizabeth; Segura, Ana María; Cepeda, Alfonso; Minotas, María

    2016-09-01

    Allergies comprise a set of highly prevalent diseases. When allergic processes are not controlled, they can endanger patients' health and lives, and have an important economic and social impact. The aim of this paper is to present a practical consensus of the scientific evidence on the use of immunotherapy in allergic diseases. A collaborative review made by various institutes and universities in Colombia was carried out upon request of the Asociación Colombiana de Alergia, Asma e Imunología, led by general practitioners, allergists, immunologists, internists and paediatricians with experience in the field of allergies. As a result, based on current national and international scientific evidence, we describe in detail what immunotherapy is about, its indications, contraindications and its economic and health benefits. Conclusions show immunotherapy as a clinically effective and safe treatment, which can substantially reduce the cost of the overall treatment of allergic patients.

  16. Superfund: Contaminated Sediments

    EPA Pesticide Factsheets

    Contaminated sediments are a significant environmental problem and contribute to the over 3,200 fish consumption advisories nationwide. The Superfund program cleans up sediment sites that present an unacceptable risk to human health or the environment.

  17. Indicators: Sediment Enzymes

    EPA Pesticide Factsheets

    Sediment enzymes are proteins that are produced by microorganisms living in the sediment or soil. They are indicators of key ecosystem processes and can help determine which nutrients are affecting the biological community of a waterbody.

  18. Sediment Toxicity Identification Evaluation

    EPA Science Inventory

    Approach combining chemical manipulations and aquatic toxicity testing, generally with whole organisms, to systematically characterize, identify and confirm toxic substances causing toxicity in whole sediments and sediment interstitial waters. The approach is divided into thre...

  19. Contaminated Sediment Core Profiling

    EPA Science Inventory

    Evaluating the environmental risk of sites containing contaminated sediments often poses major challenges due in part to the absence of detailed information available for a given location. Sediment core profiling is often utilized during preliminary environmental investigations ...

  20. Lagrangian Sediment Transport Model

    NASA Astrophysics Data System (ADS)

    Maderych, V.; Brovchenko, I.; Fenical, S.; Shepsis, V.

    2004-12-01

    A new two-dimensional Lagrangian sediment transport model was developed to simulate a wide-range of sediment transport processes, including sediment mobility under combined current and wave action, sediment transport and bed change under wave and currents effects, sediment transport patterns at nearshore coastal and offshore structures, and turbidity and sediment motion during dredging and dredged material placement. The Lagrangian technique was used to simulate transport of sediments, deposition, and re-suspension. The model can be applied to cohesive, non-cohesive, or mixed sediments. The sediment transport is simulated using bathymetry data, bed resistance characteristics, wave height and period, depth-averaged current velocity and bed material type, size and gradation, which vary throughout the model domain.The non-cohesive sediment transport model is based on a solution of two-dimensional mass conservation equations for the bed layer material and 2D equations for movement of sediment fractions either bed load or suspended load. The water column and bottom are divided into a set of layers: water layer, active layer, several active bed layers, and the bed layer. The model also takes into account the effects of armoring and changes in the bed composition. Cohesive sediments move entirely as suspended load in the water layer and sediment transport computations are based on a solution of the two-dimensional mass conservation equations for the bed layer material and two-dimensional equations for movement of sediment as suspended load. The water column and bed, as for non-cohesive sediments, was divided into a set of layers. Following the approach of Van Ledden (2002), the erosion of sediments made up of mud and sand mixtures is non-cohesive if the mud content is below a critical level. Above a critical mud content, the bed behaves cohesively. Deposition fluxes of mud and sand are independent. The sediment concentration in the water and active layer is represented by

  1. Sediment Budget and Sediment Fingerprinting as Management Strategies to Understand Sediment Contributions to Receiving Waters

    NASA Astrophysics Data System (ADS)

    Gellis, A.; Fitzpatrick, F.; Gorman-Sanisaca, L.

    2015-12-01

    A sound understanding of the sediment sources contributing to the sediment flux and the overall sediment budget of a watershed is key to total maximum daily load (TMDL) management strategies that focus on reducing sediment and sediment-related nutrient loadings to streams. This understanding can be provided by performing complementary sediment-source fingerprinting and sediment-budgeting investigations. The sediment fingerprinting approach quantifies the relative proportion of the potential sediment sources and the delivery of sediment from these sources. Sediment budget approaches provide information on the magnitude and location of the fluxes and the links between sources, sinks, and sediment output. Sediment budget approaches can include field based, photogrammetric, GIS, and modeling approaches to identify the important sources, erosion, and storage areas of sediment within a watershed. Combining sediment budget and sediment fingerprinting approaches provides resource managers with information on where to target mitigation measures that reduce erosion, and sediment delivery. Many watersheds across the U.S. have or are soon implementing TMDL allocations to reduce sediment and nutrient loadings. Streambank erosion is typically not accounted for in statistical, empirical, and process-based models, yet it is a major source of sediment in many watersheds. We present several examples of sediment budget and sediment fingerprinting studies from the Chesapeake Bay watershed and the Driftless Area, Wisconsin where information on loading of streambank sediment has been used (successfully) to shape upland and stream corridor management practices.

  2. The dirt on sediments

    USGS Publications Warehouse

    Smith, Loren M.; Euliss, Ned H. "Chip"

    2010-01-01

    In the wetland science field, sediment deposition is often thought of as being beneficial especially when one thinks of coastal estuarine systems. For example, sediments deposited from streams and rivers are necessary to naturally build and maintain tidal marshes. These sediments come from eroded upland soils in the interior of the continent. When these sediments are diverted from natural coastal deposition areas, such as occurs from river channelization, we lose marshes through subsidence as is happening throughout coastal Louisiana. However, the value of eroded soils is all a matter of hydrogeomorphic perspective.

  3. Methanogenesis in subglacial sediments.

    PubMed

    Boyd, Eric S; Skidmore, Mark; Mitchell, Andrew C; Bakermans, Corien; Peters, John W

    2010-10-01

    Methanogenic archaea have a unique role in Earth's global carbon cycle as producers of the greenhouse gas methane (CH4 ). However, despite the fact that ice covers 11% of Earth's continental landmass, evidence for methanogenic activity in subglacial environments has yet to be clearly demonstrated. Here we present genetic, biochemical and geochemical evidence indicative of an active population of methanogens associated with subglacial sediments from Robertson Glacier (RG), Canadian Rockies. Porewater CH4 was quantified in two subglacial sediment cores at concentrations of 16 and 29 ppmv. Coenzyme M (CoM), a metabolic biomarker for methanogens, was detected at a concentration of 1.3 nmol g sediment(-1) corresponding to ∼3 × 10(3) active cells g sediment(-1) . Genetic characterization of communities associated with subglacial sediments indicated the presence of several archaeal 16S rRNA and methyl CoM reductase subunit A (mcrA) gene phylotypes, all of which were affiliated with the euryarchaeal order Methanosarcinales. Further, CH4 was produced at 9-51 fmol g dry weight sediment(-1)  h(-1) in enrichment cultures of RG sediments incubated at 4°C. Collectively, these findings have important implications for the global carbon cycle in light of recent estimates indicating that the Earth's subglacial biome ranges from 10(4) to 10(6)  km(3) sediment.

  4. SEDIMENT GEOCHEMICAL MODEL

    EPA Science Inventory

    Until recently, sediment geochemical models (diagenetic models) have been only able to explain sedimentary flux and concentration profiles for a few simplified geochemical cycles (e.g., nitrogen, carbon and sulfur). However with advances in numerical methods, increased accuracy ...

  5. Indicators: Sediment Mercury

    EPA Pesticide Factsheets

    Sediment mercury is mercury that has become embedded into the bottom substrates of aquatic ecosystems. Mercury is a common pollutant of aquatic ecosystems and it can have a substantial impact on both human and wildlife health.

  6. Indicators: Streambed Sediments

    EPA Pesticide Factsheets

    Streambed sediments are fine mineral deposits and silt located on the streambed. In excess amounts, they can fill in the habitat spaces between stream cobbles and rocks where aquatic organisms live and breed.

  7. AMBIENT WATER, POREWATER, AND SEDIMENT

    EPA Science Inventory

    Sediment assessments may be performed for a variety of purposes; these include: dredging and dredged sediment disposal, for evaluations of sediments as a capping material, to determine sediment quality, to assess biological impairment and to assess the status of environment monit...

  8. Suspended Sediment Under Waves.

    DTIC Science & Technology

    1982-09-01

    Vortex Ripples 98 Grain Size Variation with Elevation over Vortex Ripples 107 Concentration Profiles over Flat Beds il1 Concentration Profiles over...investigations. The clearest results are obtained in relation to the near bed sediment distributions. Over fully developed vortex ripples we find...with the details of the turbulence or the vortex motion. Nevertheless, the latter are very important for the understanding of sediment entrainment

  9. Hydrodynamics of sediment threshold

    NASA Astrophysics Data System (ADS)

    Ali, Sk Zeeshan; Dey, Subhasish

    2016-07-01

    A novel hydrodynamic model for the threshold of cohesionless sediment particle motion under a steady unidirectional streamflow is presented. The hydrodynamic forces (drag and lift) acting on a solitary sediment particle resting over a closely packed bed formed by the identical sediment particles are the primary motivating forces. The drag force comprises of the form drag and form induced drag. The lift force includes the Saffman lift, Magnus lift, centrifugal lift, and turbulent lift. The points of action of the force system are appropriately obtained, for the first time, from the basics of micro-mechanics. The sediment threshold is envisioned as the rolling mode, which is the plausible mode to initiate a particle motion on the bed. The moment balance of the force system on the solitary particle about the pivoting point of rolling yields the governing equation. The conditions of sediment threshold under the hydraulically smooth, transitional, and rough flow regimes are examined. The effects of velocity fluctuations are addressed by applying the statistical theory of turbulence. This study shows that for a hindrance coefficient of 0.3, the threshold curve (threshold Shields parameter versus shear Reynolds number) has an excellent agreement with the experimental data of uniform sediments. However, most of the experimental data are bounded by the upper and lower limiting threshold curves, corresponding to the hindrance coefficients of 0.2 and 0.4, respectively. The threshold curve of this study is compared with those of previous researchers. The present model also agrees satisfactorily with the experimental data of nonuniform sediments.

  10. Subglacial conduits in sediments

    NASA Astrophysics Data System (ADS)

    Hewitt, Ian

    2016-04-01

    Much of the current understanding of subglacial hydrology is based on the R-channel type model, in which turbulent dissipation and melting causes a roughly semi-circular incision upwards into the ice. The prevalence of such R-channels beneath the Greenland and Antarctic ice sheets is poorly known. Beneath sediment-based ice, distributed water flow may prevail, or some form of conduits may still form due to a combination of upwards melting as well as downwards erosion into the subglacial sediments (often referred to as a canal). This study examines the dynamics of such conduits, and implications for large-scale subglacial drainage. Although a relatively standard set of equations has developed to model the evolution and efficiency of R-channels, models of sediment-floored conduits are much less well established; previous models assume steady state, or make ad hoc assumptions about the balance of processes controlling the channel walls. In this study I suggest a (relatively) simple model analogous to that for an R-channel. The model requires consideration of the energy balance that results in melting of the ice roof, and also the erosion, deposition, and creep of the sediments. Implications for the evolution of large-scale drainage systems over subglacial sediment will be discussed, for subglacial floods in Antarctica, and for subglacial erosion and landform development.

  11. Influenza-Sediment Interactions

    NASA Astrophysics Data System (ADS)

    Trusiak, A.; Block, K. A.; Katz, A.; Gottlieb, P.; Alimova, A.; Galarza, J.; Wei, H.; Steiner, J. C.

    2013-12-01

    A typical water fowl can secrete 1012 influenza virions per day. Therefore it is not unexpected that influenza virions interact with sediments in the water column. The influence of sediments on avian influenza virions is not known. With the threat of avian influenza emerging into the human population, it is crucial to understand virus survivability and residence time in a body of water. Influenza and clay sediments are colloidal particles and thus aggregate as explained by DLVO (Derjaguin & Landau, Verwey & Overbeek) theory. Of great importance is an understanding of the types of particulate or macromolecular components that bind the virus particles, and whether the virus remains biologically active. We present results of hetero-aggregation and transmission electron microscopy experiments performed with influenza A/PR8/38. Influenza particles are suspended with sediment and minimal nutrients for several days, after which the components are evaluated to determine influenza concentration and survivability. Transmission electron microscopy results are reported on the influenza-sediment aggregates to elucidate structure and morphology of the components.

  12. Sediment impacts on marine sponges.

    PubMed

    Bell, James J; McGrath, Emily; Biggerstaff, Andrew; Bates, Tracey; Bennett, Holly; Marlow, Joseph; Shaffer, Megan

    2015-05-15

    Changes in sediment input to marine systems can influence benthic environments in many ways. Sponges are important components of benthic ecosystems world-wide and as sessile suspension feeders are likely to be impacted by changes in sediment levels. Despite this, little is known about how sponges respond to changes in settled and suspended sediment. Here we review the known impacts of sedimentation on sponges and their adaptive capabilities, whilst highlighting gaps in our understanding of sediment impacts on sponges. Although the literature clearly shows that sponges are influenced by sediment in a variety of ways, most studies confer that sponges are able to tolerate, and in some cases thrive, in sedimented environments. Critical gaps exist in our understanding of the physiological responses of sponges to sediment, adaptive mechanisms, tolerance limits, and the particularly the effect of sediment on early life history stages.

  13. Autonomous sensor manager agents (ASMA)

    NASA Astrophysics Data System (ADS)

    Osadciw, Lisa A.

    2004-04-01

    Autonomous sensor manager agents are presented as an algorithm to perform sensor management within a multisensor fusion network. The design of the hybrid ant system/particle swarm agents is described in detail with some insight into their performance. Although the algorithm is designed for the general sensor management problem, a simulation example involving 2 radar systems is presented. Algorithmic parameters are determined by the size of the region covered by the sensor network, the number of sensors, and the number of parameters to be selected. With straight forward modifications, this algorithm can be adapted for most sensor management problems.

  14. Remediation technologies for contaminated sediments

    SciTech Connect

    Swanson, L.M.

    1995-09-01

    Although soil and groundwater remediation has been conducted for many years, sediment remediation is still in its infancy. Regulatory agencies are now beginning to identify areas where contaminated sediments exist and evaluate their environmental impact. As these evaluations are completed, the projects must shift focus to how these sediments can be remediated. Also as the criteria for aquatic disposal of dredged sediments become more stringent, remediation technologies must be developed to address contaminated sediments generated by maintenance dredging.This report describes the various issues and possible technologies for sediment remediation.

  15. 11. MOVABLE BED SEDIMENTATION MODELS. AUTOMATIC SEDIMENT FEEDER DESIGNED AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. MOVABLE BED SEDIMENTATION MODELS. AUTOMATIC SEDIMENT FEEDER DESIGNED AND BUILT BY WES. - Waterways Experiment Station, Hydraulics Laboratory, Halls Ferry Road, 2 miles south of I-20, Vicksburg, Warren County, MS

  16. Toxicity of contaminated sediments in dilution series with control sediments

    USGS Publications Warehouse

    Nelson, M.K.; Landrum, P.F.; Burton, G.A.; Klaine, S.J.; Crecelius, E.A.; Byl, T.D.; Gossiaux, Duane C.; Tsymbal, V.N.; Cleveland, L.; Ingersoll, Christopher G.; Sasson-Brickson, G.

    1993-01-01

    The use of dilutions has been the foundation of our approach for assessing contaminated water, and accordingly, it may be important to establish similar or parallel approaches for sediment dilutions. Test organism responses to dilution gradients can identify the degree of necessary sediment alteration to reduce the toxicity. Using whole sediment dilutions to represent the complex interactions of in situ sediments can identify the toxicity, but the selection of the appropriate diluent for the contaminated sediment may affect the results and conclusions drawn. Contaminated whole sediments were examined to evaluate the toxicity of dilutions of sediments with a diversity of test organisms. Dilutions of the contaminated sediments were prepared with differing diluents that varied in organic carbon content, particle size distribution, and volatile solids. Studies were conducted using four macroinvertebrates and a vascular, rooted plant. Responses by some test organisms followed a sigmoidal dose-response curve, but others followed a U-shaped curve. Initial dilutions reduced toxicity as expected, but further dilution resulted in an increase in toxicity. The type of diluent used was an important factor in assessing the sediment toxicity, because the control soil reduced toxicity more effectively than sand as a diluent of the same sediment. Using sediment chemical and physical characteristics as an indicator of sediment dilution may not be as useful as chemical analysis of contaminants, but warrants further investigation.

  17. SULFIDE MINERALS IN SEDIMENTS

    EPA Science Inventory

    The formation processes of metal sulfides in sediments, especially iron sulfides, have been the subjects of intense scientific research because of linkages to the global biogeochemical cycles of iron, sulfur, carbon, and oxygen. Transition metal sulfides (e.g., NiS, CuS, ZnS, Cd...

  18. PHYTOASSESSMENT OF ESTUARINE SEDIMENTS

    EPA Science Inventory

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

  19. Sediment and the environment

    NASA Astrophysics Data System (ADS)

    Hadley, Richard F.; Ongley, E. D.

    This symposium, held May 17-18 during the International Association of Hydrological Sciences Third Scientific Assembly, was organized and sponsored by the International Commission on Continental Erosion. The papers presented dealt with sediment problems and contaminants transport associated with both natural and disturbed environments. Topics discussed were divided into four general groups: sediment-associated transport of contaminants in nonpoint pollution; erosion control problems associated with mining, construction and waste disposal activities; time lag in sediment movement through drainage networks; and the modeling of runoff and sedimentation.Average attendance at each of the six sessions was about 50 persons. Of the 23 scheduled papers, 21 were presented by the authors; however, the two missing authors were replaced on the program by authors who had submitted abstracts but who did not complete their manuscripts in time for prepublication. Therefore 23 papers were presented and the program was complete. Participation by country was: Bolivia, 1; People's Republic of China, 2; Canada, 4; India, 2; Israel, 1; Netherlands, 2; United Kingdom, 1; and United States, 10.

  20. Sediment delivery after a wildfire

    USGS Publications Warehouse

    Reneau, S.L.; Katzman, D.; Kuyumjian, G.A.; Lavine, A.; Malmon, D.V.

    2007-01-01

    We use a record of sedimentation a small reservoir within the Cerro Grande burn area, New Mexico, to document postfire delivery of ash, other fine-grained sediment carried in suspension within floods, and coarse-grained sediment transported as bedload over a five-year period. Ash content of sediment layers is estimated using fallout 137Cs as a tracer, and ash concentrations are shown to rapidly decrease through a series of moderate-intensity convective storms in the first rainy season after the fire. Over 90% of the ash was delivered to the reservoir in the first year, and ash concentrations in suspended sediment were negligible after the second year. Delivery of the remainder of the fine sediment also declined rapidly after the first year despite the occurrence of higher-intensity storms in the second year. Fine sediment loads after five years remained significantly above prefire averages. Deposition of coarse-grained sediment was irregular in time and was associated with transport by snowmelt runoff of sediment stored along the upstream channel during short-duration summer floods. Coarse sediment delivery in the first four years was strongly correlated with snowmelt volume, suggesting a transport-limited system with abundant available sediment. Transport rates of coarse sediment declined in the fifth year, consistent with a transition to a more stable channel as the accessible sediment supply was depleted and the channel bed coarsened. Maximum impacts from ash and other fine-grained sediment therefore occurred soon after the fire, whereas the downstream impacts from coarse-grained sediment were attenuated by the more gradual process of bedload sediment transport. ?? 2007 Geological Society of America.

  1. Sulfur diagenesis in marine sediments

    NASA Technical Reports Server (NTRS)

    Goldhaber, M.

    1985-01-01

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

  2. Sediment Pond Removal and Enhanced Designs

    EPA Pesticide Factsheets

    Sediment Pond Removal Considerations; Scheduling, Baseflow diversion, Dewatering provisions, Sediment handling, Potential to discharge sediment, Down‐gradient sediment control(s), Erosion control(s), Stream reconstruction, Riparian vegetation.

  3. Sediment bioassays with oyster larvae

    SciTech Connect

    Chapman, P.M.; Morgan, J.D.

    1983-10-01

    Tests with naturally-occurring sediments are rare and sediment testing methodology is not standardized. The authors present a simple methodology for undertaking sediment bioassays with oyster larvae, and present data from a recent study to prove the utility of this method.

  4. Chesapeake Bay Sediment Flux Model

    DTIC Science & Technology

    1993-06-01

    that influence sediment-water fluxes. Sediment oxygen demand and sediment-water fluxes of sulfide, ammonium , nitrate , phosphate, and silica are...32- C. Nitrate Source from the Overlying Water...39- D. Nitrate Source from Nitrification ................................................................................ -40- E . M odel A

  5. COLLECTION OF UNDISTURBED SURFACE SEDIMENTS

    EPA Science Inventory

    The National Resource Council identified the need for a capability to collect undisturbed surface sediments. Surface sediments are an important source for most exposure of fish to polychlorinated biphenyls via direct uptake from water in contact with sediments. An innovative sedi...

  6. Anomalous Sediment Mixing by Bioturbation

    NASA Astrophysics Data System (ADS)

    Roche, K. R.; Aubeneau, A. F.; Xie, M.; Packman, A. I.

    2013-12-01

    Bioturbation, the reworking of sediments by animals and plants, is the dominant mode of sediment mixing in low-energy environments, and plays an important role in sedimentary biogeochemical processes. Mixing resulting from bioturbation has historically been modeled as a diffusive process. However, diffusion models often do not provide a sufficient description of sediment mixing due to bioturbation. Stochastic models, such as the continuous time random walk (CTRW) model, provide more general descriptions of mixing behavior that are applicable even when regular diffusion assumptions are not met. Here we present results from an experimental investigation of anomalous sediment mixing by bioturbation in freshwater sediments. Clean and heavy-metal-contaminated sediments were collected from Lake DePue, a backwater lake of the Illinois River. The burrowing worm species Lumbriculus variegatus was introduced to homogenized Lake DePue sediments in aerated aquaria. We then introduced inert fine fluorescent particles to the sediment-water interface. Using time-lapse photography, we observed the mixing of the fluorescent particles into the sediment bed over a two-week period. We developed image analysis software to characterize the concentration distribution of the fluorescent particles as a function of sediment depth, and applied this to the time-series of images to evaluate sediment mixing. We fit a one-dimensional CTRW model to the depth profiles to evaluate the underlying statistical properties of the mixing behavior. This analysis suggests that the sediment mixing caused by L. variegatus burrowing is subdiffusive in time and superdiffusive in space. We also found that heavy metal contamination significantly reduces L. variegatus burrowing, causing increasingly anomalous sediment mixing. This result implies that there can be important feedbacks between sediment chemistry, organism behavior, and sediment mixing that are not considered in current environmental models.

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

    USGS Publications Warehouse

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

    2005-01-01

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

  8. Sediment spiking for toxicity testing

    SciTech Connect

    Murdoch, M.H.; Norman, D.M.; Chapman, P.M.; Norman, D.M.; Quintino, V.M.

    1994-12-31

    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. Based on the concentration-response relationship(s), the relative toxicity of the spiked contaminants and their significance in sediment mixtures can be assessed. However, sediment spiking methods vary considerably. The present study details an appropriate methodology for amending sediments with a range of organic contaminant concentrations including different solvent schemes and an equilibration period. This methodology is described as appropriate because predicted and actual concentrations were similar, and responses in an acute 10-d amphipod test matched predictions and other data.

  9. Biogeochemistry of Intertidal Sediments

    NASA Astrophysics Data System (ADS)

    Jickells, T. D.; Rae, J. E.

    2005-07-01

    This authoritative volume includes contributions from a wide range of researchers of intertidal sediments. Individual chapters explore the underlying biogeochemical processes controlling the behavior of carbon, the nutrients nitrogen and phosphorus, and contaminants such as toxic organics, trace metals and artificial radionuclides in intertidal environments. The biogeochemistry of these environments is critical to understanding their ecology and management. Each of the chapters includes a comprehensive review and the results of recent research. The contributors are active researchers in this diverse and ecologically important field. This text is mainly for researchers and managers working with intertidal sediments, but it will also serve as a valuable senior undergraduate and graduate reference text in environmental chemistry, environmental science, earth science, and oceanography.

  10. Sedimentation-related meetings

    NASA Astrophysics Data System (ADS)

    The sedimentation committee would like to provide information on several meetings that took place in October 1983.The second annual meeting of the American Geomorphological Field Group was organized by S. Wells and T. Gardner and held in Chaco Canyon, N. Mex., October 7-10. Field excursions included visits to instrumented watersheds in badland areas, examination of the Quaternary history of Chaco Canyon, and investigation of fluvial problems associated with uranium mine tailings disposal and coal reclamation.

  11. Formulated sediment for use in whole-sediment toxicity testing

    SciTech Connect

    Kemble, N.E.; Dwyer, F.J.; Hardesty, D.K.; Ingersoll, C.G.

    1995-12-31

    A formulated control sediment was developed to provide consistent and acceptable biological endpoints for a variety of species used in whole sediment toxicity testing. In an attempt to develop such a sediment the authors conducted multiple tests to evaluate: (1) {alpha}-cellulose as an organic carbon source, (2) various TOC concentrations, (3) various grain sizes, (4) different food types, and (5) overlying waters. Studies were conducted with the amphipod Hyalella azteca the midges Chironomus riparius, Chironomus tentans and the oligochaete Lumbriculus variegatus in 10 d exposures and H. azteca in 28 d exposures. Sediment from West Bearskin Lake Minnesota was used as a control sediment with each species in each test. Survival of test organisms in all of the 10-d experiments, with the exception of C. riparius, was above the acceptable levels for a control sediment. Survival in the formulated sediments also was not significantly different when compared to the control sediment. Amphipod survival in the 28-d exposures was low; however, the use of reconstituted water in combination with the formulated sediment may have been a problem. The authors are currently evaluating various types of overlying water with formulated sediments and sublethal endpoints in each of the exposures (i.e., growth, sexual maturation or head capsule width).

  12. Inclined, collisional sediment transport

    NASA Astrophysics Data System (ADS)

    Berzi, Diego; Fraccarollo, Luigi

    2013-10-01

    We apply the constitutive relations of kinetic theory of granular gases to the transport of cohesionless sediments driven by a gravitational liquid turbulent stream in steady uniform conditions. The sediment-laden flow forms self-equilibrated mechanisms of resistance at the bed surface, below which the sediments are at rest. This geo-physical process takes place quite often in streams at moderate slope and may be interpreted through tools common to fluid mechanics and particle physics. Taking into account the viscous dissipation of the fluctuation energy of the particles, and using approximate methods of integration of the governing differential equations, permit to obtain a set of simple formulas for predicting how depths and flow rates adjust to the angle of inclination of the bed, without requiring additional tuning parameters besides the particle and fluid properties. The agreement with laboratory experiments performed with either plastic cylinders or gravel in water is remarkable. We also provide quantitative criteria to determine the range of validity of the theory, i.e., the values of the Shields number and the angle of inclination of the bed for which the particle stresses can be mostly ascribed to collisional exchange of momentum.

  13. Magnetism of quaternary sediments

    NASA Astrophysics Data System (ADS)

    Heller, Friedrich

    Magnetism of Quaternary sediments was the topic of a well-attended symposium held during the 13th INQUA (International Union of Quaternary Research) congress in Beijing, China, August 2-9. More than 40 papers were delivered by scientists from Belgium, England, France, Germany, Japan, New Zealand, Sweden, Switzerland, Taiwan, the United States, the Soviet Union, Yugoslavia, and other countries. The host country contributed to a productive session that was part of the first large scientific meeting to take place in Beijing after the June 4, 1989, upheaval.Nearly half of the studies focused on paleomagnetic and rock magnetic properties of loess in Alaska, Central Asia, China, and New Zealand. Magnetostratigraphic polarity dating was done at some sections in the western (Shaw et al.) and central Chinese loess plateau (Bai and Hus; Wang and Evans; Yue). The interpretation of the polarity pattern found in the western loess plateau still is not unambiguous. In the central part, certain polarity boundaries, such as the Brunhes/Matuyama (B/M) boundary, are found in slightly different stratigraphic positions (Hus et al.; Yue). In deep-sea sediments the lock-in depth of natural remanent magnetization (NRM) at the B/M boundary seems to be a linear function of sedimentation rate (de Menocal et al.). Although the magnetization process in the Chinese loess is not well understood, detailed records of polarity transitions have been reported for the B/M and the Jaramillo R→N transition (Ma et al.; Rolph).

  14. Beryllium Desorption from Sediments

    NASA Astrophysics Data System (ADS)

    Boschi, V.; Willenbring, J. K.

    2015-12-01

    Beryllium isotopes have provided a useful tool in the field of geochronology and geomorphology over the last 25 years. The amount of cosmogenic meteoric 10Be and native 9Be absorbed to soils often scales with the residence time and chemical weathering of sediments in a landscape, respectively. Thus, the concentrations in river sediment may be used to quantify the denudation of specific watersheds. When deposited in ocean sediment, these concentrations are thought to record the history of denudation on Earth over the last ~10 Ma. The use of both isotopes often relies on the premise of beryllium retention to sediment surfaces in order to preserve a landscape's erosion and weathering signature. Changes in setting, en route from the soil to fluvial system to the ocean, can cause beryllium desorption and may preclude some applications of the 10Be/9Be system. Four mechanisms were tested to determine the desorption potential of beryllium including a reduction in pH, an increase in ionic strength and complexation with soluble organic and inorganic species. These processes have the potential to mobilize beryllium into solution. For example, by both reducing the pH and increasing the ionic strength, competition for adsorption sites increases, potentially liberating beryllium from the sediment surface. In addition, organic and inorganic ligands can complex beryllium causing it to become mobilized. To determine which of these alterations influence beryllium desorption and to quantify the effect, we prepared separate solutions of beryllium bound to minerals and organic compounds and measured beryllium concentrations in solution before and after adjusting the pH, ionic strength, and changing inorganic and organic ligand concentrations. We conclude from our observations that overall, beryllium sorbed to organic compounds was more resistant to desorption relative to mineral-associated beryllium. Among the methods tested, a reduction in pH resulted in the greatest amount of

  15. Sedimentation of multicomponent viruses: evaluation of sedimentation coefficient ratios.

    PubMed

    Larcom, L L; Barnett, O W

    1978-01-01

    Ratios of the sedimentation coefficients for alfalfa mosaic virus components are shown to be independent of the virus concentration and the density of the solvent. Different numbers of components are observed in solvents of different density. This implies that in sedimentation velocity experiments an estimate of the number of components of a multicomponent virus should involve centrifugation in solvents of different density. For some viruses, estimates of the sedimentation coefficients of individual components can be obtained from the coefficient ratios observed in unfractionated solutions and the sedimentation coefficient of the most easily purified component.

  16. Sediment toxicity in Savannah Harbor

    USGS Publications Warehouse

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

    1995-01-01

    Savannah Harbor, located near the mouth of the Savannah River, Georgia and South Carolina, is impacted by industrial and municipal effluents. Potential release of contaminants stored in harbor sediments through dredging and shipping operations requires that contaminated areas be identified for proper management of the system and protection of wildlife resources. During 1991, Hyalella azteca were exposed in 10-d static-renewal toxicity tests to pore-water and solid-phase sediment samples collected from 26 sites within Savannah Harbor. Pore-water toxicity was more pronounced than that for solidphase sediment. Toxicity and reduced leaf consumption demonstrated impaired sediment quality at specific sites within Savannah Harbor and Back River. Factors responsible for the decreased sediment quality were ammonia, alkalinity, and metal concentrations (cadmium, chromium, lead, molybdenum, and nickel). Elevated concentrations of metals and toxicities in Back River sediments indicated impacts from adjacent dredge-spoil areas.

  17. Sulfur-rich Sediments

    NASA Astrophysics Data System (ADS)

    Goldhaber, M. B.

    2003-12-01

    Marine sediments with more than a few tenths of a percent of organic carbon, as well as organic-matter-bearing, nonmarine sediments with significant concentrations of sulfate in the depositional waters contain the mineral pyrite (FeS2). Pyrite, along with sulfur-bearing organic compounds, form indirectly through the metabolic activities of sulfate-reducing microorganisms. The geochemical transformations of sulfur in sediments leading to these products significantly impact the pathway of early sedimentary diagenesis, conditions for the localization of mineral deposits (Ohmoto and Goldhaber, 1997), the global cycling of sulfur and carbon, the abundance of oxygen in the Earth's atmosphere, and perhaps even the emergence of life on Earth (e.g., Russell and Hall, 1997). This chapter provides an overview of sedimentary-sulfur geochemistry from its microbial and abiologic pathways to the global consequences of these processes.The geochemistry of sulfur is complicated by its wide range of oxidation states (Table 1). Under oxidizing conditions (e.g., in the presence of atmospheric oxygen) sulfate, with sulfur in the +6 valence state, is the stable form of sulfur. Under reducing conditions (e.g., in the presence of H2), sulfide (S=-2 valent) is the stable oxidation state. However, a range of additional aqueous and solid-phase sulfur species exist with valences between these two end-members. What makes the study of sulfur geochemistry so exciting and challenging is that many of these intermediate-valent forms play key roles in sedimentary-sulfur transformations. Furthermore, many of these reactions are microbially mediated. As detailed below, these complex biogeochemical pathways are now yielding to research whose scope ranges from molecular to global level. Table 1. Forms of sulfur in marine sediments and their oxidation states Aqueous species or mineralFormulaOxidation state(s) of sulfur SulfideH2S(aq), HS-(aq)-2 Iron sulfideaFeS(s)-2 GreigiteFe3S4(s)-2, 0 PyriteFeS2(s)-2

  18. SEDIMENT TOXICITY IDENTIFICATION EVALUATION (TIE) ...

    EPA Pesticide Factsheets

    Sediment contamination in the United States has been amply documented and, in order to comply with the 1972 Clean Water Act, the U.S. Environmental Protection Agency must address the issue of toxic sediments. Contaminated sediments from a number of freshwater and marine sites have demonstrated acute and/or chronic toxicity to a variety of test species, as well as adverse ecological effects such as population declines and changes in community structure. However, simply knowing that a sediment is toxic has limited use. This document provides guidance on the performance of sediment Toxicity Identification and Evaluation (TIE). TIE methods allow for the identification of toxic chemicals or chemical classes causing observed toxicity. The identification of pollutants responsible for toxicity of contaminated sediments has broad application in a number of EPA programs as the methods can be used within the total maximum daily load (TMDL) framework, to link sediment toxicity to specific dischargers, to design cost-effective remediation programs, and to identify environmentally protective options for dredged material disposal. In addition, the identification of specific problem contaminants in sediments could prove to be very useful to EPA programs involved in the development of water or sediment quality guidelines, and the registration of new products such as pesticides. Finally, knowledge of the causes of toxicity that influence ecological changes such as community struc

  19. Transport Model of Underground Sediment in Soils

    PubMed Central

    Guangqian, Wang

    2013-01-01

    Studies about sediment erosion were mainly concentrated on the river channel sediment, the terrestrial sediment, and the underground sediment. The transport process of underground sediment is studied in the paper. The concept of the flush potential sediment is founded. The transport equation with stable saturated seepage is set up, and the relations between the flush potential sediment and water sediment are discussed. Flushing of underground sediment begins with small particles, and large particles will be taken away later. The pore ratio of the soil increases gradually. The flow ultimately becomes direct water seepage, and the sediment concentration at the same position in the water decreases over time. The concentration of maximal flushing potential sediment decreases along the path. The underground sediment flushing model reflects the flushing mechanism of underground sediment. PMID:24288479

  20. Optical sedimentation recorder

    DOEpatents

    Bishop, James K.B.

    2014-05-06

    A robotic optical sedimentation recorder is described for the recordation of carbon flux in the oceans wherein both POC and PIC particles are captured at the open end of a submersible sampling platform, the captured particles allowed to drift down onto a collection plate where they can be imaged over time. The particles are imaged using three separate light sources, activated in sequence, one source being a back light, a second source being a side light to provide dark field illumination, and a third source comprising a cross polarized light source to illuminate birefringent particles. The recorder in one embodiment is attached to a buoyancy unit which is capable upon command for bringing the sedimentation recorder to a programmed depth below the ocean surface during recordation mode, and on command returning the unit to the ocean surface for transmission of recorded data and receipt of new instructions. The combined unit is provided with its own power source and is designed to operate autonomously in the ocean for extended periods of time.

  1. Targeting sediment management strategies using sediment quantification and fingerprinting methods

    NASA Astrophysics Data System (ADS)

    Sherriff, Sophie; Rowan, John; Fenton, Owen; Jordan, Phil; hUallacháin, Daire Ó.

    2016-04-01

    Cost-effective sediment management is required to reduce excessive delivery of fine sediment due to intensive land uses such as agriculture, resulting in the degradation of aquatic ecosystems. Prioritising measures to mitigate dominant sediment sources is, however, challenging, as sediment loss risk is spatially and temporally variable between and within catchments. Fluctuations in sediment supply from potential sources result from variations in land uses resulting in increased erodibility where ground cover is low (e.g., cultivated, poached and compacted soils), and physical catchment characteristics controlling hydrological connectivity and transport pathways (surface and/or sub-surface). Sediment fingerprinting is an evidence-based management tool to identify sources of in-stream sediments at the catchment scale. Potential sediment sources are related to a river sediment sample, comprising a mixture of source sediments, using natural physico-chemical characteristics (or 'tracers'), and contributions are statistically un-mixed. Suspended sediment data were collected over two years at the outlet of three intensive agricultural catchments (approximately 10 km2) in Ireland. Dominant catchment characteristics were grassland on poorly-drained soils, arable on well-drained soils and arable on moderately-drained soils. High-resolution (10-min) calibrated turbidity-based suspended sediment and discharge data were combined to quantify yield. In-stream sediment samples (for fingerprinting analysis) were collected at six to twelve week intervals, using time-integrated sediment samplers. Potential sources, including stream channel banks, ditches, arable and grassland field topsoils, damaged road verges and tracks were sampled, oven-dried (<40oC) and sieved (125 microns). Soil and sediment samples were analysed for mineral magnetics, geochemistry and radionuclide tracers, particle size distribution and soil organic carbon. Tracer data were corrected to account for particle

  2. Acoustical Properties of Mud Sediments

    DTIC Science & Technology

    2015-09-30

    transmission loss and array response in shallow water over mud sediments and of acoustic detection, localization, and classification of objects buried...classification of objects buried in mud; and improvement of shallow water sonar systems and predictions with mud sediments. RELATED PROJECTS...Characterization Experiment. Collaboration is planned with colleagues at Woods Hole Oceanographic Institution (Jim Lynch, Tim Duda, and Ying-Tsong Lin

  3. Sediment flux and the Anthropocene.

    PubMed

    Syvitski, James P M; Kettner, Albert

    2011-03-13

    Data and computer simulations are reviewed to help better define the timing and magnitude of human influence on sediment flux--the Anthropocene epoch. Impacts on the Earth surface processes are not spatially or temporally homogeneous. Human influences on this sediment flux have a secondary effect on floodplain and delta-plain functions and sediment dispersal into the coastal ocean. Human impact on sediment production began 3000 years ago but accelerated more widely 1000 years ago. By the sixteenth century, societies were already engineering their environment. Early twentieth century mechanization has led to global signals of increased sediment flux in most large rivers. By the 1950s, this sediment disturbance signal reversed for many rivers owing to the proliferation of dams, and sediment load reduction below pristine conditions is the dominant signal today. A delta subsidence signal began in the 1930s and is now a dominant signal in terms of sea level for many coastal environments, overwhelming even the global warming imprint on sea level. Humans have engineered how most water and sediment are discharged into the coastal ocean. Hyperpycnal flow events have become more common for some rivers, and less common for other rivers. Bottom trawling is now widespread, suggesting that even continental shelves have received a significant but as yet quantified Anthropocene impact. The Anthropocene attains the level of a geological climate event, such as that seen in the transition between the Pleistocene and the Holocene.

  4. HANDBOOK: REMEDIATION OF CONTAMINATED SEDIMENTS

    EPA Science Inventory

    Contaminated sediments may pose risks to both human and environmental health. Such sediments may be found in

    large sites, such as the harbors of industrialized ports. However, they are also frequently found in smaller sites, such as streams, lakes, bayous, and rivers. In r...

  5. DESIGN CONSIDERATION INVOLVING ACTIVE SEDIMENT CAPS (PRESENTATION)

    EPA Science Inventory

    When contaminated sediments pose unacceptable risks to human health and the environment, management activities such as removal, treatment, or isolation of contaminated sediments may be required. Various capping designs are being considered for isolating contaminated sediment are...

  6. DESIGN CONSIDERATION INVOLVING ACTIVE SEDIMENT CAPS

    EPA Science Inventory

    When contaminated sediments pose unacceptable risks to human health and the environment, management activities such as removal, treatment, or isolation of contaminated sediments may be required. Various capping designs are being considered for isolating contaminated sediment are...

  7. Suspended-sediment transport measurement

    USGS Publications Warehouse

    Gray, John R.

    2007-01-01

    Of the two operationally defined phases of fluvial-sediment transport – suspended load and bedload – collection of suspended-load data is the more common. This is a reflection of a number of factors including the general predominance of suspended load over bedload in mass transport and the greater difficulty and costs associated with collecting bedload data. Acquisition of suspended-sediment data for sediment-transport computations requires collection of water-sediment samples that represent, or can be reliably adjusted to represent, the mean discharge-weighted concentration and particle-size distribution in a cross section at the time of sample collection. Analytical results from a sufficient number of representative samples obtained with concurrent water-discharge values are needed to compute suspended-sediment discharge for the period of interest.

  8. Sediments of Arabia

    NASA Technical Reports Server (NTRS)

    2005-01-01

    21 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows martian sediment in two basic forms: (1) light-toned, layered, sedimentary rock outcrops and (2) dark, windblown sand dunes. The dark sand of the dunes is most likely composed of grains rich in iron-, magnesium-, aluminum-, and silicon-bearing minerals. The hills and mounds of layered sedimentary rock were once more extensive, covering the entire scene shown here, which occurs on the floor of a crater in western Arabia Terra.

    Location near: 8.9oN, 1.2oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Autumn

  9. Estimating sediment discharge: Appendix D

    USGS Publications Warehouse

    Gray, John R.; Simões, Francisco J. M.

    2008-01-01

    Sediment-discharge measurements usually are available on a discrete or periodic basis. However, estimates of sediment transport often are needed for unmeasured periods, such as when daily or annual sediment-discharge values are sought, or when estimates of transport rates for unmeasured or hypothetical flows are required. Selected methods for estimating suspended-sediment, bed-load, bed- material-load, and total-load discharges have been presented in some detail elsewhere in this volume. The purposes of this contribution are to present some limitations and potential pitfalls associated with obtaining and using the requisite data and equations to estimate sediment discharges and to provide guidance for selecting appropriate estimating equations. Records of sediment discharge are derived from data collected with sufficient frequency to obtain reliable estimates for the computational interval and period. Most sediment- discharge records are computed at daily or annual intervals based on periodically collected data, although some partial records represent discrete or seasonal intervals such as those for flood periods. The method used to calculate sediment- discharge records is dependent on the types and frequency of available data. Records for suspended-sediment discharge computed by methods described by Porterfield (1972) are most prevalent, in part because measurement protocols and computational techniques are well established and because suspended sediment composes the bulk of sediment dis- charges for many rivers. Discharge records for bed load, total load, or in some cases bed-material load plus wash load are less common. Reliable estimation of sediment discharges presupposes that the data on which the estimates are based are comparable and reliable. Unfortunately, data describing a selected characteristic of sediment were not necessarily derived—collected, processed, analyzed, or interpreted—in a consistent manner. For example, bed-load data collected with

  10. Sediment Evaluation Framework for the Pacific Northwest

    EPA Pesticide Factsheets

    The Sediment Evaluation Framework provides a regional framework for assessment, characterization and management of sediments in the Pacific Northwest to determine suitability for unconfined in-water disposal.

  11. 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.

  12. Comparison of bulk sediment and sediment elutriate toxicity testing methods

    EPA Science Inventory

    Elutriate bioassays are among numerous methods that exist for assessing the potential toxicity of sediments in aquatic systems. In this study, interlaboratory results were compared from 96-hour Ceriodaphnia dubia and Pimephales promelas static-renewal acute toxicity tests conduct...

  13. Wood and Sediment Dynamics in River Corridors

    NASA Astrophysics Data System (ADS)

    Wohl, E.; Scott, D.

    2015-12-01

    Large wood along rivers influences entrainment, transport, and storage of mineral sediment and particulate organic matter. We review how wood alters sediment dynamics and explore patterns among volumes of instream wood, sediment storage, and residual pools for dispersed pieces of wood, logjams, and beaver dams. We hypothesized that: volume of sediment per unit area of channel stored in association with wood is inversely proportional to drainage area; the form of sediment storage changes downstream; sediment storage correlates most strongly with wood load; and volume of sediment stored behind beaver dams correlates with pond area. Lack of data from larger drainage areas limits tests of these hypotheses, but analyses suggest a negative correlation between sediment volume and drainage area and a positive correlation between wood and sediment volume. The form of sediment storage in relation to wood changes downstream, with wedges of sediment upstream from jammed steps most prevalent in small, steep channels and more dispersed sediment storage in lower gradient channels. Use of a published relation between sediment volume, channel width, and gradient predicted about half of the variation in sediment stored upstream from jammed steps. Sediment volume correlates well with beaver pond area. Historically more abundant instream wood and beaver populations likely equated to greater sediment storage within river corridors. This review of the existing literature on wood and sediment dynamics highlights the lack of studies on larger rivers.

  14. Elwha River Restoration: Sediment Management

    NASA Astrophysics Data System (ADS)

    Kimbrel, S.; Bountry, J.; Randle, T. J.; Ritchie, A.; Huginin, H.; Torrance, A.

    2013-12-01

    The removal of Elwha and Glines Canyon Dams on the Elwha River relies on controlled reservoir drawdown increments and natural river flows to erode and redistribute the reservoir sediment, estimated to be a total of 23 (× 3) million m3. To mitigate for the predicted sediment effects, facilities have been constructed for water quality and flood protection. A sediment monitoring program is being implemented by an interdisciplinary team from Reclamation and National Park Service to integrate real-time measurements with continually updated numerical model predictions. The most recent numerical reservoir modeling and monitoring results indicate about 20 to 25 percent of the reservoir sediment has been released since the start of dam removal. Monitoring results in 2012 and early 2013 confirmed that controlled reservoir drawdown increments have induced sufficient vertical and lateral erosion of delta surfaces behind both dams. Predam channel and floodplain surface has been exposed in numerous portions of Lake Aldwell, with the release of coarse and fine sediment in the first few pools below Elwha Dam. The material released from Lake Aldwell has included organic material. With the removal of about three quarters of Glines Canyon Dam and the disappearance of Lake Mills, coarse bedload sediment has been continually released into the downstream river since late fall 2012. Field measurements and numerical modeling are being used to track the progression of the sediment wave downstream to the Elwha River mouth. Initial findings are that the aggradation was greatest immediately downstream of Glines Canyon Dam, and filled pools and transformed river planform from step-pool to glide for most of the 7 mile reach between Lake Mills and Lake Aldwell. Although there has not been a major flood, winter flows and spring snowmelt have significantly reworked the released sediment and remnants of the pre-sediment release pools and rapids have re-emerged. Large wood and organics have also

  15. CADDIS Volume 2. Sources, Stressors and Responses: Sediments

    EPA Pesticide Factsheets

    Introduction to the Sediments module, when to list Sediments as a candidate cause, ways to measure Sediments, simple and detailed conceptual diagrams for Sediments, Sediments module references and literature reviews.

  16. Calculation of longshore sediment transport

    NASA Astrophysics Data System (ADS)

    Leont'yev, I. O.

    2014-03-01

    Calculation approaches to longshore transport of sandy sediments are discussed. The estimation of the total sediment transport rate is shown to be possibly based on the so-called CERC formula, where the proportionality factor K should be calculated from relationships of Bayram et al. [8] or Leont'yev [4]. In both cases, the results are very close to each other if the author's determination of the wave breaking depth is used. Under the condition of contrasting variations in the sediment grain size over the coastal profile or in the case of fragmentary sand distribution on the surface of the bed, the local approach implying process-based modeling is more effective. A model is suggested to compute the local longshore sediment transport rates.

  17. Dating sediments using luminescence signals

    SciTech Connect

    Wintle, A. )

    1993-05-01

    Before siting a nuclear power station or a nuclear waste repository, it is necessary to establish that the area has been free of earthquake activity for a sufficient period of time. Evidence of past earthquake activity is often provided by faults in surface sediments. Age limits for fault formation can be set by obtaining the depositional ages of the sediment unit in which the fault was formed and the overlying sediment. A useful technique would be one that dating could be applied to the mineral grains that make up the sediments and that would give the time that has passed since the grains were blown or washed into position. Luminescence dating techniques, of which the most well known is thermo-luminescence (TL), provide such information. This approach has been successful in dating movement on the Wasatch Fault in Utah. A combination of TL and radiocarbon dates indicated that three faulting events had occurred within the past 5000 years. 2 refs., 1 fig.

  18. CONTAMINANTS IN WATER AND SEDIMENT

    EPA Science Inventory

    The Detroit River has experienced over a century of heavy contaminant discharges from industry and municipalities. The sources of contaminants vary, and include non-point sources, combined sewer overflows, point sources, tributaries, sediments, and upstream inputs. ---
    Demonst...

  19. 7 CFR 58.134 - Sediment content.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Sediment content. 58.134 Section 58.134 Agriculture... Milk § 58.134 Sediment content. (a) Method of testing. Methods for determining the sediment content of... for the Examination of Dairy Products. Sediment content shall be based on comparison with...

  20. 7 CFR 58.134 - Sediment content.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Sediment content. 58.134 Section 58.134 Agriculture... Milk § 58.134 Sediment content. (a) Method of testing. Methods for determining the sediment content of... for the Examination of Dairy Products. Sediment content shall be based on comparison with...

  1. Sulfur cycling in freshwater sediments

    NASA Technical Reports Server (NTRS)

    Klug, M. J.

    1985-01-01

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

  2. Suspended sediment in Minnesota streams

    USGS Publications Warehouse

    Tornes, L.H.

    1986-01-01

    Analysis showed that more than 90 percent of the annual sediment load was carried during 3 to 9 months of the year. On the average, almost 25 percent of the annual sediment load was transported during April. Generally, it was found that less than 4 percent of the average annual load was transported during December, January, and February, which indicates that sampling frequency could be reduced during winter.

  3. Measuring suspended sediment: Chapter 10

    USGS Publications Warehouse

    Gray, J.R.; Landers, M.N.

    2013-01-01

    Suspended sediment in streams and rivers can be measured using traditional instruments and techniques and (or) surrogate technologies. The former, as described herein, consists primarily of both manually deployed isokinetic samplers and their deployment protocols developed by the Federal Interagency Sedimentation Project. They are used on all continents other than Antarctica. The reliability of the typically spatially rich but temporally sparse data produced by traditional means is supported by a broad base of scientific literature since 1940. However, the suspended sediment surrogate technologies described herein – based on hydroacoustic, nephelometric, laser, and pressure difference principles – tend to produce temporally rich but in some cases spatially sparse datasets. The value of temporally rich data in the accuracy of continuous sediment-discharge records is hard to overstate, in part because such data can often overcome the shortcomings of poor spatial coverage. Coupled with calibration data produced by traditional means, surrogate technologies show considerable promise toward providing the fluvial sediment data needed to increase and bring more consistency to sediment-discharge measurements worldwide.

  4. Sediment segregation by biodiffusing bivalves

    NASA Astrophysics Data System (ADS)

    Montserrat, F.; Van Colen, C.; Provoost, P.; Milla, M.; Ponti, M.; Van den Meersche, K.; Ysebaert, T.; Herman, P. M. J.

    2009-08-01

    The selective processing of sediment fractions (sand and mud; >63 μm and ≤63 μm median grain size) by macrofauna was assessed using two size classes of inert, UV-fluorescent sediment fraction tracers (luminophores). The luminophores were applied to the sediment surface in 16 m 2 replicated plots, defaunated and control, and left to be reworked by infauna for 32 days. As the macrofaunal assemblage in the ambient sediment and the control plots was dominated by the common cockle Cerastoderma edule, this species was used in an additional mesocosm experiment. The diversity, abundance and biomass of the defaunated macrobenthic assemblage did not return to control values within the experimental period. Both erosion threshold and bed elevation increased in the defaunated plots as a response to the absence of macrofauna and an increase in microphytobenthos growth. In the absence of macrobenthos, we observed an accretion of 7 mm sediment, containing ca. 60% mud. Image analysis of the vertical distribution of the different luminophore size classes showed that the cockles preferentially mobilised fine material from the sediment, thereby rendering it less muddy and effectively increasing the sand:mud ratio. Luminophore profiles and budgets of the mesocosm experiment under "no waves-no current" conditions support the field data very well.

  5. Sedimentation dynamics about salt features

    SciTech Connect

    Lowrie, A.; Blake, D.W.

    1985-02-01

    Detailed side-scan sonar and gridded bathymetric surveys on continental margins reveal the existence of numerous submarine canyons. Recently published compilations of current velocities in submarine canyons indicate that alternating and undirectionaly flows often exceed 20-30 cm/sec with peak velocities ranging from 70 to 100 cm/sec. Current meters attached to the ocean floor have been lost at current velocities of 190 cm/sec. Such velocities are ample to transport sand-size sediments. The results of DSDP Leg 96 show the existence of massive sands and gravels on the Louisiana slope, deposited during the last glacial advance. Thus, present physical oceanographic data may be an analog to conditions during glacially induced lowered sea levels. Salt ridges and domes underlie much of the Louisiana slope, determining morphology. Submarine canyons lace the slope. Given a prograding shelf, the net sediment transport routes will be down the submarine canyons. Sediment deposition patterns around the salt ridges and domes include parallel-bedded foredrifts on the upslope side, lee drifts on the downslope side, and moats along the lateral flanks of the salt features. Major differences exist between the sedimentation patterns around a ridge and a dome. The size and shape of the flow pattern will determine whether there can be a flow over the salt feature with a resulting turbulent wave that may influence sedimentation. Sedimentation patterns about salt features on the present slope should be applicable to similar paleoenvironments.

  6. Fine sediments suppress detritivory on coral reefs.

    PubMed

    Tebbett, Sterling B; Goatley, Christopher H R; Bellwood, David R

    2017-01-30

    Increasing sediment inputs are recognised as an important factor leading to coral reef degradation. However, the role of sediments in ecological processes is poorly understood. This study used paired-choice trials to quantify the effects of sediment grain size and chemical composition on feeding by the abundant detritivorous reef fish, Ctenochaetus striatus. The size of sediments from algal turfs were also compared to those ingested by reef-dwelling C. striatus. Algal turfs containing coarser sediments were preferred by C. striatus, while sediment composition (reefal carbonates vs. riverine silicates) had little effect. On the reef, C. striatus ingested finer sediments than those present in algal turfs. C. striatus appears to prefer algal turfs with coarser sediments as this facilitates ingestion of fine detrital particles, while finer sediments prevent selective feeding on detritus. These findings suggest that fine sediments from terrestrial runoff or dredging may be detrimental to feeding by detritivorous species.

  7. Relationship of sediment discharge to streamflow

    USGS Publications Warehouse

    Colby, B.R.

    1956-01-01

    The relationship between rate of sediment discharge and rate of water discharge at a cross section of a stream is frequently expressed by an average curve. This curve is the sediment rating curve. It has been widely used in the computation of average sediment discharge from water discharge for periods when sediment samples were not collected. This report discusses primarily the applications of sediment rating curves for periods during which at least occasional sediment samples were collected. Because sediment rating curves are of many kinds, the selection of the correct kind for each use is important. Each curve should be carefully prepared. In particular, the correct dependent variable must be used or the slope of the sediment rating curve may be incorrect for computing sediment discharges. Sediment rating curves and their applications were studied for the following gaging stations: 1. Niobrara River near Cody, Nebr. 2. Colorado River near Grand Canyon, Ariz. 3. Rio Grande at San Martial, N. Mex. 4. Rio Puerto near Bernardo, N. Mex. 5. White River near Kadoka, S. Dak. 6. Sandusky River near Fremont, Ohio Except for the Sandusky River and the Rio Puerco, which transport mostly fine sediment, one instantaneous sediment rating curve was prepared for the discharge of suspended sands, at each station, and another for the discharge of sediment finer than 0.082 millimeter. Each curve was studied separately, and by trial-end-error multiple correlation some of the factors that cause scatter from the sediment rating curves were determined. Average velocity at the cross section, Water temperature, and erratic fluctuations in concentration seemed to be the three major factors that caused departures from the sediment rating curves for suspended sands. The concentration of suspended sands varied with about the 2.8 power of the mean velocity for the four sediment, rating curves for suspended sands. The effect of water temperature was not so consistent as that of velocity and

  8. Sediment fingerprinting in Northern Jordan - approaching sediment comparability

    NASA Astrophysics Data System (ADS)

    Kraushaar, Sabine; Schumann, Thomas; Ollesch, Gregor; Siebert, Christian; Vogel, Hans-Joerg

    2014-05-01

    Jordan has a quantitative and qualitative water problem in combination with a growing demand by population increase. Around 65% of the freshwater used in Jordan is reported to originate from surface waters and reservoirs. Sediment loads harm the quality of these water bodies and fill up dams. A sediment fingerprint pilot study was implemented in an exemplary catchment in the NW of Jordan to investigate the possibility of geochemical differentiation between 6 sediment sources and calculate their relative contribution to the sink, the Wadi Al-Arab reservoir. The sediment fingerprint method relies on the comparability of sediment properties of the sources and the sink. However, selection processes during transport, preferential adsorption of elements on fine particles, and differences in inorganic carbonate content prevent a direct comparison. In previous studies this has been solved through selective sampling and analyzing certain grain size fractions or the mathematical derivation of correction factors. As no pre-knowledge existed in the Wadi Al-Arab catchment, selective grain size sampling would have implied the risk of neglecting important information already during the sampling process. Hence, a method was established that includes several steps to identify influential parameters (IPs), eliminate their impact and take account of their interrelations. It is based on a stepwise multiple regression analysis model (SMRAM) and generates element specific correction factors that take account for possible interdependencies between influential parameters as clay percentage and total organic and inorganic carbonates. In the further selection process of suitable elements for the fingerprint, we complemented the common used methods by a solubility analysis. Therefore, water profiles were physicochemical investigated in the dam lake. Differences in the chemical milieus during transport and sedimentation that affect the conservativeness of the chosen elements could be detected

  9. Elwha River Restoration: Sediment Management

    NASA Astrophysics Data System (ADS)

    Randle, T. J.; Bountry, J.; Ritchie, A.; Hugunin, H.; Torrence, A.

    2012-12-01

    The 1 to 2-year removal of Elwha and Glines Canyon Dams on the Elwha River relies on controlled reservoir drawdown increments and natural river flows to erode and redistribute the reservoir sediment, estimated to be a total of 18 million m3. To mitigate for the predicted sediment effects, facilities have been constructed for water quality and flood protection, including water treatment plants, new wells, a new surface water intake, raising the height of existing levees, and the construction of new levees. A sediment monitoring program is being implemented by an interdisciplinary team from Reclamation and National Park Service to integrate real-time measurements with continually updated numerical model predictions. The most recent numerical reservoir modeling and monitoring results indicate about 50 percent of the reservoir sediment will remain in the reservoir while another 50 percent is predicted to be released downstream during dam removal and a few high flood periods following the completion of dam removal. Early monitoring results confirm that lowering the reservoir pool in a controlled increment, and then holding the reservoir pool at constant elevation, is inducing sufficient vertical and lateral erosion of the exposed delta surface. Predam channel and floodplain surface has been exposed in numerous portions of Lake Aldwell. The first major coarse sediment released from Lake Aldwell occurred in mid-April. This sediment release along with continued erosion during spring snowmelt of 2012 has resulted in deposition of the first few river pools below Elwha Dam. Deposition on riffles, where velocities are higher, has not occurred. Therefore, no major change to flood stage is predicted from the initial sediment release. The material released from Lake Aldwell has included organic material. About half of Glines Canyon Dam has been removal and Lake Mills is about one-quarter of its original size. Future monitoring will focus on continued tracking of the lateral

  10. Extraterrestrial Matter Chronometry of Sediments

    NASA Astrophysics Data System (ADS)

    Peucker-Ehrenbrink, B.; Waters, C. A.; Hoffman, P. F.; Kurz, M. D.

    2010-12-01

    Tracer records of extraterrestrial matter (ET) accumulation in sediments suggest that ET accretion rates are reasonable constant on time scales relevant to sediment accumulation in terrestrial and marine environments (1000-100,000 years), except during impact events. Geochemical tracers of ET matter in sediments are therefore informative rate indicators applicable to individual samples. This alleviates the need for interpolating rates between known chronometric tie points. The most sensitive tracers of ET accretion include noble gases, particularly helium, and the heavy platinum group elements osmium, iridium and platinum. Helium and osmium have tell-tale isotope signatures that are sensitive indicators of terrestrial vs. extraterrestrial pedigree. Here we investigate the use of coupled helium-osmium isotope and helium, osmium, iridium and platinum concentration analyses to determine sedimentation rates across Neoproterozoic glacial terminations. Bodiselitsch et al. (Science 308, 2005, 239ff) suggested that significant iridium anomalies at transitions from glacial to postglacial sediments constrain the duration of Neoproterozoic Marinoan glaciation to at least 3, and most likely 12 million years. Our data on Marinoan sections from NW Canada and Namibia reveal no large ET matter anomaly, and support a more nuanced interpretation of coupled geochemical indicators of accretion of ET matter across those transitions. Our records provide insights into environmental changes during periods of Neoproterozoic climate change.

  11. 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.

  12. Precambrian clastic sedimentation systems

    NASA Astrophysics Data System (ADS)

    Eriksson, P. G.; Condie, K. C.; Tirsgaard, H.; Mueller, W. U.; Altermann, W.; Miall, A. D.; Aspler, L. B.; Catuneanu, O.; Chiarenzelli, J. R.

    1998-09-01

    The unique and evolving nature of the Precambrian geological environment in many ways was responsible for significant differences between Precambrian clastic sedimentary deposits and their Phanerozoic-modern equivalents. Some form of plate tectonics, with rapid microplate collisions and concomitant volcanic activity, is inferred to have led to the formation of greenstone belts. Explosive volcanism promoted common gravity-flow deposits within terrestrial greenstone settings, with braided alluvial, wave/storm-related and tidal coastline sediments also being preserved. Late Archaean accretion of greenstone terranes led to emergence of proto-cratons, where cratonic and rift sedimentary assemblages developed, and these became widespread in the Proterozoic as cratonic plates stabilised. Carbonate deposition was restricted by the paucity of stable Archaean terranes. An Early Precambrian atmosphere characterised by greenhouse gases, including CO 2, in conjunction with a faster rotation of the Earth and reduced albedo, provide a solution to the faint young Sun paradox. As emergent continental crust developed, volcanic additions of CO 2 became balanced by withdrawal due to weathering and a developing Palaeoproterozoic microbial biomass. The reduction in CO 2, and the photosynthetic production of O 2, led to aerobic conditions probably being achieved by about 2 Ga. Oceanic growth was allied to atmospheric development, with approximately 90% of current ocean volume being reached by about 4 Ga. Warm Archaean and warm, moist Palaeoproterozoic palaeoclimates appear to have become more arid after about 2.3 Ga. The 2.4-2.3 Ga Huronian glaciation event was probably related to continental growth, supercontinent assembly and weathering-related CO 2 reduction. Despite many analogous features among both Precambrian and younger sedimentary deposits, there appear to be major differences as well. Two pertinent examples are rare unequivocal aeolian deposits prior to about 1.8 Ga and an

  13. Radionuclides in Chesapeake Bay sediments

    NASA Technical Reports Server (NTRS)

    Cressy, P. J., Jr.

    1976-01-01

    Natural and manmade gamma-ray emitting radionuclides were measured in Chesapeake Bay sediments taken near the Calvert Cliffs Nuclear Power Plant site. Samples represented several water depths, at six locations, for five dates encompassing a complete seasonal cycle. Radionuclide contents of dry sediments ranged as follows: Tl-208, 40 to 400 pCi/kg; Bi-214, 200 to 800 pCi/kg; K, 0.04 to 2.1 percent; Cs-137 5 to 1900 pCi/kg; Ru106, 40 to 1000 pCikg Co60, 1 to 27 pCi/kg. In general, radionuclide contents were positively correlated with each other and negatively correlated with sediment grain size.

  14. Rheometry of natural sediment slurries

    USGS Publications Warehouse

    Major, Jon J.; ,

    1993-01-01

    Recent experimental analyses of natural sediment slurries yield diverse results yet exhibit broad commonality of rheological responses under a range of conditions and shear rates. Results show that the relation between shear stress and shear rate is primarily nonlinear, that the relation can display marked hysteresis, that minimum shear stress can occur following yield, that physical properties of slurries are extremely sensitive to sediment concentration, and the concept of slurry yield strength is still debated. New rheometric analyses have probed viscoelastic behavior of sediment slurries. Results show that slurries composed of particles ??? 125 ?? m exhibit viscoelastic responses, and that shear stresses are relaxed over a range of time scales rather than by a single response time.

  15. Ancient aqueous sedimentation on Mars

    SciTech Connect

    Goldspiel, J.M.; Squyres, S.W. )

    1991-02-01

    Viking orbiter images are presently used to calculate approximate volumes for the inflow valleys of the ancient cratered terrain of Mars; a sediment-transport model is then used to conservatively estimate the amount of water required for the removal of this volume of debris from the valleys. The results obtained for four basins with well-developed inflow networks indicate basin sediment thicknesses of the order of tens to hundreds of meters. The calculations further suggest that the quantity of water required to transport the sediment is greater than that which could be produced by a single discharge of the associated aquifer, unless the material of the Martian highlands was very fine-grained and noncohesive to depths of hundreds of meters. 48 refs.

  16. Dynamical simulations of sedimenting spheres

    SciTech Connect

    Ladd, A.J.C. )

    1993-02-01

    The sedimentation of monodisperse suspensions of rigid spheres has been studied by dynamical simulation; computational techniques are described and numerical results are reported. It has been found that there is a slow relaxation of the suspension microstructure during sedimentation, so that compared with the initial equilibrium distribution, there is an increased number of pairs of particles near contact; this leads to a 5%--10% increase in the average sedimentation velocity. Individual particle velocities fluctuate about the mean fall speed; these fluctuations are large and persist for long times. The resulting hydrodynamically induced dispersion of the particles can be characterized by strongly anisotropic diffusion coefficients; however, the dispersion process is non-Fickian at high solids concentrations.

  17. Criteria for a sediment data set

    USGS Publications Warehouse

    Glysson, Douglas G.

    1989-01-01

    The transport of sediment through a hydrologic system or basin is an extremely complex phenomenon. Many factors affect this movement. Criteria are established for an 'ultimate' or complete sediment data set, and guidelines are given for the collection of alluvial data. The paper describes what parameters need to be measured and stored to obtain a complete sediment and hydraulic data set that could be used to compute sediment transport using any prominently known sediment-transport equation. The criteria address only the collection of data for noncohesive sediment.

  18. Data Evaluation Report for the Lower Rouge River Sediment Investigation

    EPA Pesticide Factsheets

    Describes a study of contaminated sediment, analyzes results, and makes recommendations for sediment remediation. Includes aerial views of study locations, photo log, data tables of sediment analysis.

  19. Hydroxyatrazine in soils and sediments

    USGS Publications Warehouse

    Lerch, R.N.; Thurman, E.M.; Blanchard, P.E.

    1999-01-01

    Hydroxyatrazine (HA) is the major metabolite of atrazine in most surface soils. Knowledge of HA sorption to soils, and its pattern of stream water contamination suggest that it is persistent in the environment. Soils with different atrazine use histories were collected from four sites, and sediments were collected from an agricultural watershed. Samples were exhaustively extracted with a mixed-mode extractant, and HA was quantitated using high performance liquid chromatography with UV detection. Atrazine, deethylatrazine (DEA), and deisopropylatrazine (DIA) were also measured in all samples. Concentrations of HA were considerably greater than concentrations of atrazine, DEA, and DIA in all soils and sediments studied. Soil concentrations of HA ranged from 14 to 640 ??g/kg with a median concentration of 84 ??g/kg. Sediment concentrations of HA ranged from 11 to 96 ??g/kg, with a median concentration of 14 ??g/kg. Correlations of HA and atrazine concentrations to soil properties indicated that HA levels in soils were controlled by sorption of atrazine. Because atrazine hydrolysis is known to be enhanced by sorption and pH extremes, soils with high organic matter (OM) and clay content and low pH will result in greater atrazine sorption and subsequent hydrolysis. Significant correlation of HA concentrations to OM, pH, and cation exchange capacity of sediments indicated that mixed-mode sorption (i.e., binding by cation exchange and hydrophobic interactions) was the mechanism controlling HA levels in sediment. The presence of HA in soils and stream sediments at the levels observed support existing hypotheses regarding its transport in surface runoff. These results also indicated that persistence of HA in terrestrial and aquatic ecosystems is an additional risk factor associated with atrazine usage.

  20. Reactive iron in marine sediments

    NASA Technical Reports Server (NTRS)

    Canfield, Donald E.

    1989-01-01

    The influence of reactive iron oxides on sediment pore-water chemistry is considered in detail. A carefully calibrated extraction scheme is used to determine the depth distributions of reactive iron phases at two very different localities: the relatively iron-rich Mississippi Delta and the relatively iron-poor FOAM site in Long Island Sound. Closed system incubations are used to characterize the rates of reaction between sulfide and both naturally occurring and pure iron mineral phases. Rates of iron liberation to pore solution are measured in the presence and absence of sulfate reduction, and the origin of dissolved iron in organic-rich sediments is speculated upon.

  1. Sediment transport and sedimentation along the Amazon floodplain

    SciTech Connect

    Dunne, T.; Mertes, A.K.L.; Meade, R.H.

    1985-01-01

    As the Amazon River leaves the Andean foothills and crosses the structural trough in its Brazilian segment, it receives a large increment of discharge, but a small increase in sediment load from the bounding cratons. The gradient of the river declines gradually from Iquitos, Peru, downstream to Coari, Brazil, before increasing downstream to the vicinity of Manaus as the river crosses a structural arch. Between Manaus and Obidos, the river slope declines sharply. The interplay of the variable gradient and increasing discharge creates a pattern of boundary shear stress and sediment transport which the authors have defined by measurement and calculation. The downstream divergence of suspended and bed load transport is responsible for the patterns of aggradation, channel behavior and floodplain morphology. Aggradation has been computed on the basis of three years of sediment transport measurements; floodplain morphology was documented from radar photography and navigation charts; and channel migration from these charts and from aerial and satellite photography. In the reach between the Peruvian border and Coari, the river deposits sand bars within and alongside the channel and shifts laterally at a relatively rapid rate, forming a scroll-bar floodplain topography with long, narrow lakes. In the middle, steeper reach no net aggradation was measured, sand-bar development and channel shifting are limited. Below Manaus, the rapid decline in gradient and the large influx of Andean sediment from the Rio Madeira result in deposition of almost the entire sand load and a portion of the silt.

  2. Sediment reworking rates in deep sediments of the Mediterranean Sea.

    PubMed

    Barsanti, M; Delbono, I; Schirone, A; Langone, L; Miserocchi, S; Salvi, S; Delfanti, R

    2011-07-01

    Different pelagic areas of the Mediterranean Sea have been investigated in order to quantify physical and biological mixing processes in deep sea sediments. Herein, results of eleven sediment cores sampled at different deep areas (> 2000 m) of the Western and Eastern Mediterranean Sea are presented. ²¹⁰Pb(xs) and ¹³⁷Cs vertical profiles, together with ¹⁴C dating, are used to identify the main processes characterising the different areas and, finally, controlling mixing depths (SML) and bioturbation coefficients (D(b)). Radionuclide vertical profiles and inventories indicate that bioturbation processes are the dominant processes responsible for sediment reworking in deep sea environments. Results show significant differences in sediment mixing depths and bioturbation coefficients among areas of the Mediterranean Sea characterised by different trophic regimes. In particular, in the Oran Rise area, where the Almeria-Oran Front induces frequent phytoplankton blooms, we calculate the highest values of sediment mixing layers (13 cm) and bioturbation coefficients (0.187 cm² yr⁻¹), and the highest values of ²¹⁰Pb(xs) and ¹³⁷Cs inventories. Intermediate values of SML and D(b) (~6 cm and ~0.040 cm² yr⁻¹, respectively) characterise the mesothrophic Algero-Balearic basin, while in the Southern Tyrrhenian Sea mixing parameters (SML of 3 cm and D(b) of 0.011 cm² yr⁻¹ are similar to those calculated for the oligotrophic Eastern Mediterranean (SML of 2 cm and D(b) of ~0.005 cm² yr⁻¹).

  3. Chesapeake Bay sediment flux model. Final report

    SciTech Connect

    Di Toro, D.M.; Fitzpatrick, J.J.

    1993-06-01

    Formulation and application of a predictive diagenetic sediment model are described in this report. The model considers two benthic sediment layers: a thin aerobic layer in contact with the water column and a thicker anaerobic layer. Processes represented include diagenesis, diffusion, particle mixing, and burial. Deposition of organic matter, water column concentrations, and temperature are treated as independent variables that influence sediment-water fluxes. Sediment oxygen demand and sediment-water fluxes of sulfide, ammonium, nitrate, phosphate, and silica are predicted. The model was calibrated using sediment-water flux observations collected in Chesapeake Bay 1985-1988. When independent variables were specified based on observations, the model correctly represented the time series of sediment-water fluxes observed at eight stations in the Bay and tributaries.... Chesapeake Bay, Models, Sediments, Dissolved oxygen, Nitrogen Eutrophication, Phosphorus.

  4. Beverage Cans Used for Sediment Collection.

    ERIC Educational Resources Information Center

    Studlick, Joseph R. J.; Trautman, Timothy A.

    1979-01-01

    Beverage cans are well suited for sediment collection and storage containers. Advantages include being free, readily available, and the correct size for many samples. Instruction for selection, preparation, and use of cans in sediment collection and storage is provided. (RE)

  5. Beneficial Use Of Contaminated Sediment

    EPA Science Inventory

    The western portion of the Lake George Branch of the Indian Harbor Canal (IHC) is no longer used for commercial purposes, but contains petroleum contaminated sediments. The IHC is considered an important habitat for many animal species. Several future development projects have ...

  6. Prediction of bedload sediment transport for heterogeneous sediments in shape

    NASA Astrophysics Data System (ADS)

    Durafour, Marine; Jarno, Armelle; Le Bot, Sophie; Lafite, Robert; Marin, François

    2015-04-01

    Key words: Particle shape, in-situ measurements, bedload transport, heterogeneous sediments Bedload sediment transport in the coastal area is a dynamic process mainly influenced by the type of hydrodynamic forcings involved (current and/or waves), the flow properties (velocity, viscosity, depth) and sediment heterogeneity (particle size, density, shape). Although particle shape is recognized to be a significant factor in the hydrodynamic behavior of grains, this parameter is not currently implemented in bedload transport formulations: firstly because the mechanisms of initiation of motion according to particle shape are still not fully understood, and secondly due to the difficulties in defining common shape parameters. In March 2011, a large panel of in-situ instruments was deployed on two sites in the Eastern English Channel, during the sea campaign MESFLUX11. Samples of the sediment cover available for transport are collected, during a slack period, per 2cm thick strata by divers and by using a Shipeck grab. Bedload discharges along a tidal cycle are also collected with a Delft Nile Sampler (DNS; Gaweesh and Van Rijn, 1992, 1994) on both sites. The first one is characterized by a sandy bed with a low size dispersion, while the other study area implies graded sediments from fine sands to granules. A detailed analysis of the data is performed to follow the evolution of in-situ bedload fluxes on the seabed for a single current. In-situ measurements are compared to existing formulations according to a single fraction approach, using the median diameter of the mixture, and a fractionwise approach, involving a discretization of the grading curve. Results emphasize the interest to oscillate between these two methods according to the dispersion in size of the site considered. The need to apply a hiding/exposure coefficient (Egiazaroff, 1965) and a hindrance factor (Kleinhans and Van Rijn, 2002) for size heterogeneous sediments is also clearly highlighted. A really good

  7. MODELING FRAMEWORK FOR EVALUATING SEDIMENTATION IN STREAM NETWORKS: FOR USE IN SEDIMENT TMDL ANALYSIS

    EPA Science Inventory

    A modeling framework that can be used to evaluate sedimentation in stream networks is described. This methodology can be used to determine sediment Total Maximum Daily Loads (TMDLs) in sediment impaired waters, and provide the necessary hydrodynamic and sediment-related data t...

  8. Modern Reservoir Sedimentation Management Techniques with Examples

    NASA Astrophysics Data System (ADS)

    Annandale, G. W.

    2014-12-01

    Implementation of reservoir sedimentation management approaches results in a win-win scenario, it assists in enhancing the environment by preserving river function downstream of dams while concurrently providing opportunities to sustainably manage water resource infrastructure. This paper summarizes the most often used reservoir sedimentation management techniques with examples of where they have been implemented. Three categories can be used to classify these technologies, i.e. catchment management, sediment routing and sediment removal. The objective of catchment management techniques is to minimize the amount of sediment that may discharge into a reservoir, thereby reducing the loss of storage space due to sedimentation. Reservoir routing is a set of techniques that aim at minimizing the amount of sediment that may deposit in a reservoir, thereby maximizing the amount of sediment that may be passed downstream. The third group consists of techniques that may be used to remove previously deposited sediment from reservoirs. The selection of reservoir sedimentation management approaches is site specific and depends on various factors, including dam height, reservoir volume, reservoir length, valley shape, valley slope, sediment type and hydrology. Description of the different reservoir sedimentation management techniques that are used in practice will be accompanied by case studies, including video, illustrating criteria that may be used to determine the potential success of implementing the techniques.

  9. Regional Models for Sediment Toxicity Assessment

    EPA Science Inventory

    This paper investigates the use of empirical models to predict the toxicity of sediment samples within a region to laboratory test organisms based on sediment chemistry. In earlier work, we used a large nationwide database of matching sediment chemistry and marine amphipod sedim...

  10. Dimpling in loose granular sediments

    NASA Astrophysics Data System (ADS)

    Díaz-Hernández, Jose Luis; Yepes, Jorge

    2010-05-01

    Dimpling is the name given to the centimetre-scale collapse of granular deposits covering the interior of alteration shelters in semi-arid badlands. The development of micro-collapses is favoured by the stable conditions found in these shelters, where they are safe from water flows, rain impact, and animal or human traffic. The floor of these shelters is usually covered by several centimetres of sandy sediment resulting from the alteration of the rocky substratum and characterised by apparently very low density and high porosity. We have observed that the dimpling phenomenon does not depend on the mineralogy of the sands and occurs in dry conditions. The dimples are the shapes resulting from this process and are fragile, conical depressions ranging from 1 to 12 cm in diameter. They are generally over 3 cm in depth, depending on the depth of the sandy layer. The dimples can be classified into three groups by diameter (Ø): Ø≤1cm, 1cm≤Ø≤10 cm and Ø≥10 cm. These three morphometrical ranges suggest three evolutionary stages of the shapes. The main mechanisms of evolution are the coalescence of neighbouring dimples and the accommodation of the lateral walls towards more open, stable shapes. In this process, the slope of the dimple walls decreases to the angle of equilibrium, or internal friction angle of the sediment, when they acquire a more stable, dense structure. This evolution occurs naturally over several months. The process begins when sufficient sediment with low apparent density accumulates. This takes place by vertical accretion of particles from the shelter walls, which pile up in a stack-of-cards type structure. The increase in weight of the sediment column causes punctual micro-collapses when the limit of the sediment's self-supporting capacity is reached. The process is gravitational. Thermal variations can also condition the structural instability of the sediment due to the dilation-retraction changes undergone by the sediment grains. We can

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

    NASA Astrophysics Data System (ADS)

    McDavitt, B.; O'Connor, M.

    2003-12-01

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

  12. Major sedimentation issues for the USGS

    USGS Publications Warehouse

    Jobson, Harvey E.; Andrews, Edmund D.; ,

    1990-01-01

    Historically, sediment information has been used primarily in planning for engineering structures that were designed to meet a single or a very limited number of objectives. Today most water-resource systems are fully developed, but society is asking that the existing systems be operated to meet multiple objectives, which often were not considered in the original system design. Sediment related problems that seem to be of highest priority today include: 1. The relation of sediment transport to the transport and fate of attached pollutants, 2. Documentation of the mean sediment concentration and load as well as the natural variability of instantaneous sediment concentrations and loads as related to land use, and 3. Evaluation of the effect of sediment on fish and wildlife habitat. The sediment program of the U.S. Geological Survey (USGS) is changing in response to these changing priorities as it attempts to remain relevant and responsive to current problems.

  13. Using sediment particle size distribution to evaluate sediment sources in the Tobacco Creek Watershed

    NASA Astrophysics Data System (ADS)

    Liu, Cenwei; Lobb, David; Li, Sheng; Owens, Philip; Kuzyk, ZouZou

    2014-05-01

    Lake Winnipeg has recently brought attention to the deteriorated water quality due to in part to nutrient and sediment input from agricultural land. Improving water quality in Lake Winnipeg requires the knowledge of the sediment sources within this ecosystem. There are a variety of environmental fingerprinting techniques have been successfully used in the assessment of sediment sources. In this study, we used particle size distribution to evaluate spatial and temporal variations of suspended sediment and potential sediment sources collected in the Tobacco Creek Watershed in Manitoba, Canada. The particle size distribution of suspended sediment can reflect the origin of sediment and processes during sediment transport, deposition and remobilization within the watershed. The objectives of this study were to quantify visually observed spatial and temporal changes in sediment particles, and to assess the sediment source using a rapid and cost-effective fingerprinting technique based on particle size distribution. The suspended sediment was collected by sediment traps twice a year during rainfall and snowmelt periods from 2009 to 2012. The potential sediment sources included the top soil of cultivated field, riparian area and entire profile from stream banks. Suspended sediment and soil samples were pre-wet with RO water and sieved through 600 μm sieve before analyzing. Particle size distribution of all samples was determined using a Malvern Mastersizer 2000S laser diffraction with the measurement range up to 600μm. Comparison of the results for different fractions of sediment showed significant difference in particle size distribution of suspended sediment between snowmelt and rainfall events. An important difference of particle size distribution also found between the cultivated soil and forest soil. This difference can be explained by different land uses which provided a distinct fingerprint of sediment. An overall improvement in water quality can be achieved by

  14. Smoke and Sediments in Sicily

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The waters along the shoreline of Sicily appear bright aquamarine in this image from April 7, 2002. Although other satellite images occasionally show lightening along the coast of Sicily and southern Italy, the water is unusually bright in this image. The bright water may have been caused by a recent storm that either stirred up sediment from relatively shallow sea bottom, or could be a springtime phytoplankton bloom. (Distinguishing phytoplankton from sediment is one of the challenges facing NASA researchers who study life in the oceans from satellites.) Another interesting feature of this image is the smoke plume from Mount Etna that is streaming almost directly to the East (right). Mt. Etna is one of the world's most active volcanos, and erupts up to several times a year. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  15. Sediment problems in urban areas

    USGS Publications Warehouse

    Guy, Harold P.

    1970-01-01

    One obstacle to a scientific recognition and an engineering solution to sediment-related environmental problems is that such problems are bound in conflicting and generally undefinable political and institutional restraints. Also, some of the difficulty may involve the fact that the scientist or engineer, because of his relatively narrow field of investigation, cannot always completely envision the less desirable effects of his work and communicate alternative solutions to the public. For example, the highway and motor-vehicle engineers have learned how to provide the means by which one can transport himself from one point to another with such great efficiency that a person's employment in this country is now commonly more than 5 miles from his residence. However, providing such efficient personal transport has created numerous serious environmental problems. Obstacles to recognition of and action to control sediment problems in and around urban areas are akin to other environmental problems with respect to the many scientific, engineering, economic, and social aspects.

  16. Sediment quality and aquatic life assessment

    SciTech Connect

    Adams, W.J. ); Kimerle, R.A.; Barnettt, J.W. Jr. )

    1992-10-01

    The protection of aquatic resources has assumed national and global prominence. Oil spills, medical wastes, and plastic debris presence on beaches, ocean incineration, ocean disposal of garbage and dredged materials, pesticide and fertilizer runoff, contaminated harbors, and diminishing fisheries have focused public attention on the need to adequately protect marine and freshwater resources-including sediments. Sediments are repositories for physical debris and [open quotes]sinks[close quotes] for a wide variety of chemicals. The concern associated with the chemicals sorbed to sediments is that many commercial species and food chain organisms spend a major portion of their life-cycle living in or on aquatic sediments. This provides a pathway for these chemicals to be consumed by higher aquatic life and wildlife, including avian species as well as humans. Direct transfer of chemicals from sediments to organisms is now considered to be a major route of exposure for many species. Concern has increased over the number of incidences of tumors being observed in many species of fish, especially those that have direct contact with sediments. These issues are focusing attention on sediment contamination and highlight the fact that sediments are an important resource. The purposes of this article are to provide background information on the status of sediment assessment in the United States, a review of the existing methods available for assessing sediment quality, an analysis of the complexity and uncertainty of the sediment assessment methodologies, and a proposed approach that utilizes the unique attributes of many of these methods in a tiered sediment assessment strategy. The authors hope that this sediment assessment strategy will help provide a mechanism for achieving cleaner sediments and wate rin the nation's aquatic ecosystems.

  17. Oxic and Anoxic Regions of Subseafloor Sediment

    NASA Astrophysics Data System (ADS)

    D'Hondt, S.; Pockalny, R. A.; Spivack, A. J.; Inagaki, F.; Murray, R. W.; Adhikari, R. R.; Gribsholt, B.; Kallmeyer, J.; McKinley, C. C.; Morono, Y.; Røy, H.; Sauvage, J.; Ziebis, W.

    2015-12-01

    Dissolved oxygen content defines two broad categories of subseafloor sediment. In areas with high rates of microbial respiration, most of the sediment column is anoxic and active anaerobic microbial communities are present for hundreds of meters or more below the seafloor. In these regions, O2 and aerobic communities penetrate only millimeters to centimeters into the sediment from the sediment-water interface. In some areas of active fluid flow through the underlying basalt, O2 may also penetrate meters upward into the sediment from the basalt. In areas with low sedimentary respiration, O2 and aerobic communities penetrate tens of meters downward from the seafloor and may persist throughout the entire sediment column. IODP Expedition 329 showed that microbial cells and aerobic respiration persist through the entire sediment sequence (to depths of at least 75 meters below seafloor) in the South Pacific Gyre. Extrapolating from these results and a global relationship of O2 penetration depth to sedimentation rate and sediment thickness, we suggest that oxygen and aerobic communities occur throughout the entire sediment sequence in 15-44% of the Pacific and 9-37% of the global seafloor. Subduction of sediment from largely anoxic regions and subduction of sediment and basalt from fully oxic regions are respectively sources of reduced and oxidized material to the mantle. The balance between oxic and anoxic regions has presumably changed considerably throughout Earth history. Regions with largely anoxic sediment and regions with fully oxic sediment present fundamentally different opportunities for understanding of (i) paleoceanographic history and (ii) the nature of microbial life under extreme energy limitations.

  18. Dynamic simulation of particle sedimentation

    NASA Astrophysics Data System (ADS)

    Zhang, Zhongzhen; Prosperetti, Andrea

    2004-11-01

    The sedimentation of 1024 spheres has been simulated via a recently developed method:Physalis Method. Particles are initially randomly distributed and periodic boundary conditions are assumed. The time evolution of the particle spatial distribution is studied by meassuering the structure factor. Properties of particles velocity distribution, e.g. variance, time autocorrelation, have been studied. The effects of particle rotation and collision are discussed.

  19. Submarine lithification of carbonate sediments.

    PubMed

    Milliman, J D

    1966-08-26

    Recrystallized planktonic limestones from two guyots in the North Atlantic are in oxygen-isotopic equilibrium with their present ambient waters, suggesting submarine lithifica tion and recrystallization. The early stages of submarine lithification of carbonates may involve precipitation of, and replacement by, magnesium-rich calcite; with time this may invert to magnesium-poor calcite. This type of lithification probably requires very low rates of sediment accumulation.

  20. Sediment Vertical Flux in Unsteady Sheet Flows

    NASA Astrophysics Data System (ADS)

    Hsu, T.; Jenkins, J. T.; Liu, P. L.

    2002-12-01

    In models for sediment suspension, two different boundary conditions have been employed at the sediment bed. Either the sediment concentration is given or the vertical flux of sediment is specified. The specification of the latter is usually called the pick-up function. Recently, several developments towards a better understanding of the sediment bed boundary condition have been reported. Nielson et al (Coastal Engineering 2002, 45, p61-68) have indicated a better performance using the sediment vertical flux as the bed boundary condition in comparisons with experimental data. Also, Drake and Calantoni (Journal of Geophysical Research 2001, 106, C9, p19859-19868) have suggested that in the nearshore environment with its various unsteady flow conditions, the appropriate sediment boundary conditions of a large-scale morphology model must consider both the magnitude the free stream velocity and the acceleration of the flow. In this research, a small-scale sheet flow model based on the two-phase theory is implemented to further study these issues. Averaged two-phase continuum equations are presented for concentrated flows of sediment that are driven by strong, fully developed, unsteady turbulent shear flows over a mobile bed. The particle inter-granular stress is modeled using collisional granular flow theory and a two-equation closure for the fluid turbulence is adopted. In the context of the two-phase theory, sediment is transported through the sediment vertical velocity. Using the fully developed sediment phase continuity equation, it can be shown that the vertical velocity of the sediment must vanish when the flow reaches a steady state. In other words, in fully developed conditions, it is the unsteadiness of the flow that induces the vertical motion of the sediment and that changes the sediment concentration profile. Therefore, implementing a boundary condition based on sediment vertical flux is consistent with both the two-phase theory and with the observation

  1. Sediment transport measurements: Chapter 5

    USGS Publications Warehouse

    Diplas, P.; Kuhnle, R.; Gray, J.; Glysson, D.; Edwards, T.; García, Marcelo H.

    2008-01-01

    Sediment erosion, transport, and deposition in fluvial systems are complex processes that are treated in detail in other sections of this book. Development of methods suitable for the collection of data that contribute to understanding these processes is a still-evolving science. Sediment and ancillary data are fundamental requirements for the proper management of river systems, including the design of structures, the determination of aspects of stream behavior, ascertaining the probable effect of removing an existing structure, estimation of bulk erosion, transport, and sediment delivery to the oceans, ascertaining the long-term usefulness of reservoirs and other public works, tracking movement of solid-phase contaminants, restoration of degraded or otherwise modified streams, and assistance in the calibration and validation of numerical models. This chapter presents techniques for measuring bed-material properties and suspended and bed-load discharges. Well-established and relatively recent, yet adequately tested, sampling equipment and methodologies, with designs that are guided by sound physical and statistical principles, are described. Where appropriate, the theory behind the development of the equipment and guidelines for its use are presented.

  2. Oligocene tectonics and sedimentation, California

    USGS Publications Warehouse

    Nilsen, T.H.

    1984-01-01

    During the Oligocene epoch, California was marked by extensive nonmarine sedimentation, in contrast to its pre-Oligocene and post-Oligocene depositional history. The Oligocene continental deposits are especially widespread in southern California and fill a number of small and generally partly restricted basins. Fluvial facies in many basins prograded over previously deposited lower Tertiary turbidites. Volcanism, from widespread centers, was associated with the nonmarine sedimentation. However, some basins remained marine and a few contain Oligocene turbidites and pelagic sediments deposited at bathyal depths. The Oligocene redbeds of California do not form a post-orogenic molasse sequence comparable to the Old Red Sandstone or Alpine molasse. They are synorogenic and record local uplift of basins and surrounding source areas. Late Cretaceous to contemporary orogenesis in California has been generally characterized by the formation of small restricted basins of variable depth adjacent to small upland areas in response to strike-slip faulting. Deposition of Oligocene redbeds was associated with climatic change from warm and humid to cold and semiarid, and a global lowering of sea level. Oligocene tectonism occurred during the transition from subduction of the Farallon Plate to initiation of the modern San Andreas transform system. However, the major influence that caused uplift, formation of fault-bounded basins, and extensive redbed deposition, especially in southern California, was the approach of the Pacific-Farallon spreading ridge to the western margin of California. ?? 1984.

  3. 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

  4. Mercury dynamics in lake sediments

    NASA Astrophysics Data System (ADS)

    Feyte, Stéphane; Gobeil, Charles; Tessier, André; Cossa, Daniel

    2012-04-01

    Triplicate porewater depth-profiles of pH and concentrations of total Hg (HgT), methylmercury (MeHg), Fe, Mn, sulfate, total sulfide, total zero-valent sulfur, organic C and major ions were determined at two sampling dates in a perennially oxygenated basin and a seasonally anoxic basin from Lake Tantaré, a Canadian Shield lake. The vertical distribution of HgT, MeHg, acid volatile sulfide, total S, Fe, Mn, Al and organic C were also determined in dated sediment cores from the same lake basins and from the deepest site of two other lakes, one also located in the Canadian Shield and the other in the Northeastern part of the Appalachian Mountains. Application of a one-dimensional transport-reaction equation to the dissolved HgT and MeHg profiles constrains the depth intervals (zones) where these species are produced or consumed in the sedimentary column and yields estimates of net reaction rates of HgT or MeHg in each of the zones as well as their fluxes at the sediment-water interface. Dissolved HgT and MeHg diffused from the overlying water into the sediments, except for MeHg at one of the sampling dates in the perennially oxygenated basin. About 97% and 50% of the MeHg flux to the sediments is presently deposited with settling particles in the perennially oxygenated and seasonally anoxic basins, respectively. Removal of porewater HgT and MeHg occurred at all dates and sampling sites. Comparison of the consumption zones of porewater HgT and MeHg with the profiles of ancillary parameters, coupled with thermodynamic calculations, suggest that pure Hg mineral phases do not form in the sediments, that HgT and MeHg adsorption onto authigenic Fe oxyhydroxides occurs in minor proportions, and that the association of HgT and MeHg to Fe sulfide phases or sulfidized organic matter is possible. Assuming that the net consumption of MeHg in the porewaters was essentially due to demethylation, an apparent first-order rate constant for MeHg demethylation of 0.04-0.8 d-1 was

  5. Fluvial sediments a summary of source, transportation, deposition, and measurement of sediment discharge

    USGS Publications Warehouse

    Colby, B.R.

    1963-01-01

    This paper presents a broad but undetailed picture of fluvial sediments in streams, reservoirs, and lakes and includes a discussion of the processes involved in the movement of sediment by flowing water. Sediment is fragmental material that originates from the chemical or physical disintegration of rocks. The disintegration products may have many different shapes and may range in size from large boulders to colloidal particles. In general, they retain about the same mineral composition as the parent rocks. Rock fragments become fluvial sediment when they are entrained in a stream of water. The entrainment may occur as sheet erosion from land surfaces, particularly for the fine particles, or as channel erosion after the surface runoff has accumulated in streams. Fluvial sediments move in streams as bedload (particles moving within a few particle diameters of the streambed) or as suspended sediment in the turbulent flow. The discharge of bedload varies with several factors, which may include particle size and a type of effective shear on the surface of the streambed. The discharge of suspended sediment depends partly on concentration of moving sediment near the streambed and hence on discharge of bedload. However, the concentration of fine sediment near the streambed varies widely, even for equal flows, and, therefore, the discharge of fine sediment normally cannot be computed theoretically. The discharge of suspended sediment also depends on velocity, turbulence, depth of flow, and fall velocity of the particles. In general, the coarse sediment transported by a stream moves intermittently and is discharged at a rate that depends on properties of the flow and of the sediment. If an ample supply of coarse sediment is available at the surface of the streambed, the discharge of the coarse sediment, such as sand, can be roughly computed from properties of the available sediment and of the flow. On the other hand, much of the fine sediment in a stream usually moves nearly

  6. AsMA journal covers, a history.

    PubMed

    Day, Pamela C

    2014-01-01

    The cover of our journal has changed quite often over the years. As we look forward to changing the name and design of the journal, it seems appropriate to reflect on the previous journal titles and covers. A brief history follows.

  7. New Zealand sediment toxicity testing methodologies

    SciTech Connect

    Hickey, C.W.; Roper, D.S.; Nipper, M.; Martin, M.L.

    1995-12-31

    Sediment toxicity testing in New Zealand is developing against a background of an increasing public desire for environmental protection and strict legislative requirements that contaminant discharges should not have any significant adverse effects on aquatic life. The importance of sediment contamination and its potential immediate and long term adverse effects on aquatic biota in general is becoming widely recognized, This has lead to an effort to develop acute and chronic sediment toxicity tests with organisms representative of the New Zealand indigenous biota. An amphipod species occurring in both freshwater and estuarine environments, Chaetocorophium cf lucasi, and the marine bivalve Macomona liliana, a common inhabitant of intertidal sandflats, have been evaluated for their sensitivity to natural sediment characteristics. The amphipod and bivalve are presently being used for testing sediment acute (10d) and chronic toxicity (20--30d), with survival and growth as test endpoints, and the bivalve has shown to be a useful organism for behavioral tests with burial and sediment avoidance by movement and drifting as endpoints. The estuarine bivalve Arthritica bifurca, abundant in muddy sediments, is a self-fertilizing hermaphroditic species and its suitability for sediment tests with a reproductive endpoint is underway. Freshwater sphaeriid bivalves, Sphaerium novazelandiae, are also being used for survival, growth, reproduction and behavioral endpoints. Sensitivity to reference toxicants and results for contaminated sediments will be presented and discussed in relation to sediment quality criteria developed elsewhere.

  8. Determination of brevetoxin in recent marine sediments.

    PubMed

    Mendoza, Wilson G; Mead, Ralph N; Brand, Larry E; Shea, Damian

    2008-11-01

    Harmful algal blooms (HAB) of Karenia brevis (K. brevis) produce a suite of lipid soluble polyether brevetoxins, known to cause environmental, health and economic ill effects. There is evidence that K. brevis has increased in abundance over the past 50 years, but the dataset is incomplete. The objective of this paper was to analyze sediment from an area where K. brevis blooms have occurred and investigate if these compounds are incorporated into the underlying sediment, thus potentially allowing the use of brevetoxins as an indicator of past K. Brevis blooms. The results from LC-ESI-MS-MS analyses of brevetoxin analogs detected in surficial sediments from three sites (Fort Meyers Beach [FMB], Big Hickory Pass [BHP] and Big Carlos Pass [BCP]) along the Southwest Florida coastline with prior HAB history are promising. The analogs detected from BHP sediments were PbTx-2 and PbTx-3 with values of 0.81 and 3.1 ng g(-1) dry sediment, respectively. The detected PbTx-2 from BCP was 3.6 ng g(-1) dry sediment, while the detected PbTx-3 from BCP was 9.7 ng g(-1) dry sediment. PbTx-3 was only detected at the FMB site (2.7 ng g(-1) dry sediment). The detection of brevetoxins in recent sediments where K. brevis have occurred indicates brevetoxin incorporation into marine sediments.

  9. Importance of elemental mercury in lake sediments.

    PubMed

    Bouffard, Ariane; Amyot, Marc

    2009-02-01

    Mercury (Hg) redox changes in sediments are poorly studied and understood, even though they potentially control Hg availability for methylation and can alter sediment-water Hg exchange. Elemental Hg (Hg(0)) concentrations in sediments of two Canadian Shield lakes were assessed by thermodesorption. Hg(0) concentrations in sediments varied between 6.3 and 60.3 pg g(-1) (wet weight) which represented 7.4-28.4% of total mercury (HgT) concentration. Hg(0) concentrations were similar in both lakes. Hg(0) was rapidly adsorbed on sediments in controlled adsorption experiments and surface sediments sampled in summer had a stronger affinity for Hg(0) than deeper sediments and sediments sampled in fall. This adsorption was positively correlated to organic matter content and negatively related to particle grain size, pH and oxygen concentration in overlying water. This study demonstrates that Hg(0) is a prevalent species in sediments, but not in porewater, because of the high sorptive capacity of sediments towards Hg(0). Its potential availability towards Hg methylating bacteria remains to be determined.

  10. Deposition of fine sediment in turbulent conditions

    NASA Astrophysics Data System (ADS)

    Capapé, Sergi; Martín-Vide, Juan Pedro; Colombo, Ferran

    2015-04-01

    Sediment transport is the responsible for reshaping the stream bed. There are multiple studies on the bedform formation, but data is scarce when the bed originates from a sediment-laden flow and the sediment is in the very fine range. The aim of this work is to evaluate the suspended sediment concentration at which deposition starts to occur. Specifically, non-cohesive fine sediment made of silica particles (D50 = 0.004 mm, σg = 2.45) is used to assess the transport of sediment in the wash-load size range. The second objective arises as a consequence of studying the first one: to analyse the relation between the flow properties and a developed bed composed of very fine sediment. The experiments are performed in a 15 m-long 0.37 m-wide flume (SIMGEO UB-CSIC, Faculty of Geology, University of Barcelona). Water and sediment are recirculated. The clean smooth metal surface of the flume is set to be the initial condition in each run. Hydraulic conditions in the flume are quasi-uniform. Flow parameters are controlled by the use of an ADV Vectrino, a current meter, a thermometer and siphons to collect samples of the suspension. Preliminary results show that very fine sediment transported in suspension settles on the bed as function of the elapsed time and the suspended sediment concentration. Bedform development may show the typical stages unless for the first partial-covered bed stage in which solitary lunate ripples migrate downstream.

  11. Nearshore sediment thickness, Fire Island, New York

    USGS Publications Warehouse

    Locker, Stanley D.; Miselis, Jennifer L.; Buster, Noreen A.; Hapke, Cheryl J.; Wadman, Heidi M.; McNinch, Jesse E.; Forde, Arnell S.; Stalk, Chelsea A.

    2017-04-03

    Investigations of coastal change at Fire Island, New York (N.Y.), sought to characterize sediment budgets and determine geologic framework controls on coastal processes. Nearshore sediment thickness is critical for assessing coastal system sediment availability, but it is largely unquantified due to the difficulty of conducting geological or geophysical surveys across the nearshore. This study used an amphibious vessel to acquire chirp subbottom profiles. These profiles were used to characterize nearshore geology and provide an assessment of nearshore sediment volume. Two resulting sediment-thickness maps are provided: total Holocene sediment thickness and the thickness of the active shoreface. The Holocene sediment section represents deposition above the maximum flooding surface that is related to the most recent marine transgression. The active shoreface section is the uppermost Holocene sediment, which is interpreted to represent the portion of the shoreface thought to contribute to present and future coastal behavior. The sediment distribution patterns correspond to previously defined zones of erosion, accretion, and stability along the island, demonstrating the importance of sediment availability in the coastal response to storms and seasonal variability. The eastern zone has a thin nearshore sediment thickness, except for an ebb-tidal deposit at the wilderness breach caused by Hurricane Sandy. Thicker sediment is found along a central zone that includes shoreface-attached sand ridges, which is consistent with a stable or accretional coastline in this area. The thickest overall Holocene section is found in the western zone of the study, where a thicker lower section of Holocene sediment appears related to the westward migration of Fire Island Inlet over several hundred years.

  12. Issues Relating To Sediment Toxicity Testing And Bioaccumulation Of Persistent Chemicals In SRS Sediments

    SciTech Connect

    WINONA, SPECHT

    2005-03-01

    Many chemical contaminants that enter a water body in an aqueous form are ultimately deposited to the sediments. Over time, the concentrations of contaminants in sediments may build up to concentrations that are much higher than those found in the water column. However, not all chemicals present in sediments are toxic/bioavailable. Factors that affect bioavailability include aqueous solubility, pH, redox, and composition of the sediment matrix (grain size, mineral constituents, organic matter), and for metals, the quantity of acid volatile sulfides that are present in the sediments. Many sediments contain multiple chemical contaminants, which may interact synergistically or antagonistically with respect to toxicity.

  13. 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.

    2016-07-11

    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.

  14. Sediment supply versus local hydraulic controls on sediment transport and storage in a river with large sediment loads

    USGS Publications Warehouse

    Dean, David; Topping, David; Schmidt, John C.; Griffiths, Ronald; Sabol, Thomas

    2016-01-01

    The Rio Grande in the Big Bend region of Texas, USA, and Chihuahua and Coahuila, Mexico, undergoes rapid geomorphic changes as a result of its large sediment supply and variable hydrology; thus, it is a useful natural laboratory to investigate the relative importance of flow strength and sediment supply in controlling alluvial channel change. We analyzed a suite of sediment transport and geomorphic data to determine the cumulative influence of different flood types on changing channel form. In this study, physically based analyses suggest that channel change in the Rio Grande is controlled by both changes in flow strength and sediment supply over different spatial and temporal scales. Channel narrowing is primarily caused by substantial deposition of sediment supplied to the Rio Grande during tributary-sourced flash floods. Tributary floods have large suspended-sediment concentrations, occur for short durations, and attenuate rapidly downstream in the Rio Grande, depositing much of their sediment in downstream reaches. Long-duration floods on the mainstem have the capacity to enlarge the Rio Grande, and these floods, released from upstream dams, can either erode or deposit sediment in the Rio Grande depending upon the antecedent in-channel sediment supply and the magnitude and duration of the flood. Geomorphic and sediment transport analyses show that the locations and rates of sand erosion and deposition during long-duration floods are most strongly controlled by spatial changes in flow strength, largely through changes in channel slope. However, spatial differences in the in-channel sediment supply regulate sediment evacuation or accumulation over time in long reaches (greater than a kilometer).

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

    SciTech Connect

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

    1994-07-01

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

  16. Suspended sediment and sediment-associated contaminants in San Francisco Bay

    USGS Publications Warehouse

    Schoellhamer, D.H.; Mumley, T.E.; Leatherbarrow, J.E.

    2007-01-01

    Water-quality managers desire information on the temporal and spatial variability of contaminant concentrations and the magnitudes of watershed and bed-sediment loads in San Francisco Bay. To help provide this information, the Regional Monitoring Program for Trace Substances in the San Francisco Estuary (RMP) takes advantage of the association of many contaminants with sediment particles by continuously measuring suspended-sediment concentration (SSC), which is an accurate, less costly, and more easily measured surrogate for several trace metals and organic contaminants. Continuous time series of SSC are collected at several sites in the Bay. Although semidiurnal and diurnal tidal fluctuations are present, most of the variability of SSC occurs at fortnightly, monthly, and semiannual tidal time scales. A seasonal cycle of sediment inflow, wind-wave resuspension, and winnowing of fine sediment also is observed. SSC and, thus, sediment-associated contaminants tend to be greater in shallower water, at the landward ends of the Bay, and in several localized estuarine turbidity maxima. Although understanding of sediment transport has improved in the first 10 years of the RMP, determining a simple mass budget of sediment or associated contaminants is confounded by uncertainties regarding sediment flux at boundaries, change in bed-sediment storage, and appropriate modeling techniques. Nevertheless, management of sediment-associated contaminants has improved greatly. Better understanding of sediment and sediment-associated contaminants in the Bay is of great interest to evaluate the value of control actions taken and the need for additional controls. ?? 2007 Elsevier Inc. All rights reserved.

  17. Sediment ingestion of two sympatric shorebird species

    USGS Publications Warehouse

    Hui, C.A.; Beyer, W.N.

    1998-01-01

    Black-bellied Plovers (Pluvialis squatarola) have short bills and primarily peck while foraging whereas Willets (Catoptrophorus semipalmatus) have long bills and primarily probe with bills open in sediments. Intestinal digesta were collected from these species at sympatric overwintering sites in southern California near San Diego to relate sediment ingestion to bill length and feeding behavior. Plover digesta contained an estimated 29% sediment, and Willet digesta an estimated 3% sediment. Techniques based on acid insoluble ash and on the elemental markers of Al, Fe, and Ti in digesta provided similar results. High Ca concentrations in Willet digesta and our observations suggested that the willets in our sample fed primarily on molluscs and crustaceans. Sediment ingestion may be species specific, not necessarily linked to bill length or probing behaviors, and may greatly affect a bird?s exposure to environmental contaminants in sediment.

  18. Sediment measurement in estuarine and coastal areas

    NASA Technical Reports Server (NTRS)

    Shelley, P. E.

    1976-01-01

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

  19. South Florida Coastal Sediment Ecological Risk Assessment.

    PubMed

    Julian, Paul

    2015-08-01

    This study evaluated the degree of sediment contamination in several South Florida estuaries. During the 2010 National Condition Assessment, Florida Fish and Wildlife Research Institute collected water column, sediment and biotic data from estuaries across the entire state of Florida. Sediments were analyzed for arsenic, cadmium, chromium, lead, mercury, zinc and total polychlorinated biphenyls and were compared relative to empirically derived sediment quality guidelines. As a result of this data collection and assessment effort, it was determined that the degree of contamination with respect to sediment was low for all southern Florida estuaries assessed, except the Miami River which was determined to be considerably contaminated. However only one monitoring location was used to assess the Miami River, and as such should be viewed with caution. A low degree of contamination was determined for Biscayne Bay sediments, possibly indicating a recovery from its previously reported higher contaminant level.

  20. Arsenic in stream sediments of northern Alabama

    USGS Publications Warehouse

    Goldhaber, M.B.; Irwin, Elise; Atkins, Brian; Lee, Lopaka; Black, D.D.; Zappia, Humbert; Hatch, Joe; Pashin, Jack; Barwick, L.H.; Cartwright, W.E.; Sanzolone, Rick; Rupert, Leslie; Kolker, Allan; Finkelman, Robert

    2001-01-01

    OVERVIEW OF ARSENIC IN STREAM SEDIMENTS The overall range of arsenic in the NURE stream sediments was from 0.3 to 44 mg/kg sediment (ppm) As in the sample data set. The mean value was 4.3 ppm with a standard deviation of 4.1 ppm. For comparison, the crustal abundance of arsenic is 1.8 ppm (Taylor, 1964). Shale is higher, with average values of 15 ppm. Coal samples from the entire USGS National Coal Resource Data System coal database (Finkelman, 1994) average 24 ppm arsenic. A study of stream sediments from throughout the U.S. by the USGS NAWQA program reported that the 75th percentile for arsenic in 541 stream sediments was 9.5 ppm (Rice, 1999). Given the relatively low crustal abundance of arsenic, a number of stream-sediment samples in this study may be considered geochemically anomalous in this element.

  1. Continental margin sedimentation: from sediment transport to sequence stratigraphy

    USGS Publications Warehouse

    Nittrouer, Charles A.; Austin, James A.; Field, Michael E.; Kravitz, Joseph H.; Syvitski, James P.M.; Wiberg, Patricia L.; Nittrouer, Charles A.; Austin, James A.; Field, Michael E.; Kravitz, Joseph H.; Syvitski, James P. M.; Wiberg, Patricia L.

    2007-01-01

    This volume on continental margin sedimentation brings together an expert editorial and contributor team to create a state-of-the-art resource. Taking a global perspective, the book spans a range of timescales and content, ranging from how oceans transport particles, to how thick rock sequences are formed on continental margins. - Summarizes and integrates our understanding of sedimentary processes and strata associated with fluvial dispersal systems on continental shelves and slopes - Explores timescales ranging from particle transport at one extreme, to deep burial at the other - Insights are presented for margins in general, and with focus on a tectonically active margin (northern California) and a passive margin (New Jersey), enabling detailed examination of the intricate relationships between a wide suite of sedimentary processes and their preserved stratigraphy - Includes observational studies which document the processes and strata found on particular margins, in addition to numerical models and laboratory experimentation, which provide a quantitative basis for extrapolation in time and space of insights about continental-margin sedimentation - Provides a research resource for scientists studying modern and ancient margins, and an educational text for advanced students in sedimentology and stratigraphy

  2. Dewatering of contaminated river sediments

    NASA Technical Reports Server (NTRS)

    Church, Ronald H.; Smith, Carl W.; Scheiner, Bernard J.

    1994-01-01

    Dewatering of slurries has been successfully accomplished by the proper use of polymers in flocculating the fine particulate matter suspended in mineral processing streams. The U.S. Bureau of Mines (USBM) entered into a cooperative research effort with the U.S. Army Corps of Engineers (Corps) for the purpose of testing and demonstrating the applicability of mining flocculation technology to dredging activities associated with the removal of sediments from navigable waterways. The Corps has the responsibility for maintaining the navigable waterways in the United States. Current technology relies primarily on dredging operations which excavate the material from the bottom of waterways. The Corps is testing new dredging technology which may reduce resuspension of sediments by the dredging operation. Pilot plant dredging equipment was tested by the Corps which generated larger quantities of water when compared to conventional equipment, such as the clam shell. The transportation of this 'excess' water adds to the cost of sediment removal. The process developed by the USBM consists of feed material from the barge being pumped through a 4-in line by a centrifugal pump and exiting through a 4-in PVC delivery system. A 1,000-gal fiberglass tank was used to mix the polymer concentrate. The polymer was pumped through a 1-in line using a variable speed progressive cavity pump and introduced to the 4-in feed line prior to passing through a 6-in by 2-ft static mixer. The polymer/feed slurry travels to the clarifying tank where the flocculated material settled to the bottom and allowed 'clean' water to exit the overflow. A pilot scale flocculation unit was operated on-site at the Corps' 'Confined Disposal Facility' in Buffalo, NY.

  3. Notes on sedimentation activities calendar year 1977

    USGS Publications Warehouse

    ,

    1979-01-01

    The need for disseminating current information on activities in the field of sedimentation was proposed by the Chairman of the Federal Interagency River Basin Committee's Subcommittee on Sedimentation shortly after the subcommittee was formed in May 1946. At the fifth meeting of the subcommittee on September 17, 1946, the members approved this proposal and agreed to the issuance of a quarterly report as one means of effecting better coordination of the work of various Federal agencies in the field of sedimentation.

  4. Integrated Model for the Acoustics of Sediments

    DTIC Science & Technology

    2014-09-30

    acoustic interaction with the ocean floor including penetration, reflection and scattering in support of MCM and ASW needs. OBJECTIVES The...and smoothly transition from one type of sediment into another. This is necessary because it has been observed that ocean sediments are often...often too slow to be efficiently coupled to compressional waves in ocean sediments, and thereofore viewed as less important in sonar applications

  5. Biological Assessment of Upper Mississippi River Sediments.

    DTIC Science & Technology

    1980-12-01

    burrowed into the sediment layer, they were active and appeared to be in good condition. 10. Daphnia magna , a small water column crustacean known as...fleas Daphnia magna were conducted, both involving exposure to suspended particulate phase (SPP) of each of the four UMR sediments. The SPP, which is...Minnesota River sediment caused the least mortality to every other species tested. Water flea - Daphnia magna 37. The survival of D. magna in Experiment 1

  6. Integrated Field Screening for Rapid Sediment Characterization

    DTIC Science & Technology

    2004-08-01

    Screening for Rapid Sediment Characterization August 2004 Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the...Integrated Field Screening for Rapid Sediment Characterization 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...acceptance of three field screening techniques to delineate chemical concentrations and potential biological effects of sediment contaminants. Defining

  7. Sediment Budget: Mississippi Sound Barrier Islands

    DTIC Science & Technology

    2011-05-01

    TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) U.S. Army Engineer Research and Development Center,Coastal and...beaches, infrastructure, and navigation channels to increasing storm energy. The exchange of sediment between the barrier island littoral drift ...represent deposition (green to blue). 2375 Regional Sediment Budget Zones of erosion and accretion were identified throughout the sediment budget

  8. Urine sediment from a Chihuahua.

    PubMed

    Pallatto, Valarie; Wood, Michael; Grindem, Carol

    2005-12-01

    A 6-year-old, intact male Chihuahua was presented with stranguria and painful urination of 5 days duration. Cystine crystals were observed in low numbers in unstained urine sediment preparations, and a diagnosis of cystinuria was made. Uroliths were removed surgically from the urethra and the bladder, and mineral analysis indicated the stones were composed of 100% cystine. Cystinuria results from an inherited defect in renal tubular transport of cystine that affects many breeds and has been found as an autosomal recessive trait in Newfoundlands. Accurate identification of cystine crystals in urine is an important means of diagnosing cystinuria.

  9. SEDIMENT TOTAL ORGANIC CARBON: IS THIS A USEFUL INDICATOR OF SEDIMENT CONDITION FOR PACIFIC NORTHWEST ESTUARIES?

    EPA Science Inventory

    Total organic carbon (TOC) content of sediments has been used as an indicator of benthic community condition during multiple cycles of the EPA National Coastal Assessment (NCA). Because percent TOC is generally positively correlated with sediment percent fines, previous analyses...

  10. Suspended sediments limit coral sperm availability

    PubMed Central

    Ricardo, Gerard F.; Jones, Ross J.; Clode, Peta L.; Humanes, Adriana; Negri, Andrew P.

    2015-01-01

    Suspended sediment from dredging activities and natural resuspension events represent a risk to the reproductive processes of coral, and therefore the ongoing maintenance of reefal populations. To investigate the underlying mechanisms that could reduce the fertilisation success in turbid water, we conducted several experiments exposing gametes of the corals Acropora tenuis and A. millepora to two sediment types. Sperm limitation was identified in the presence of siliciclastic sediment (230 and ~700 mg L−1), with 2–37 fold more sperm required to achieve maximum fertilisation rates, when compared with sediment-free treatments. This effect was more pronounced at sub-optimum sperm concentrations. Considerable (>45%) decreases in sperm concentration at the water’s surface was recorded in the presence of siliciclastic sediment and a >20% decrease for carbonate sediment. Electron microscopy then confirmed sediment entangled sperm and we propose entrapment and sinking is the primary mechanism reducing sperm available to the egg. Longer exposure to suspended sediments and gamete aging further decreased fertilisation success when compared with a shorter exposure. Collectively, these findings demonstrate that high concentrations of suspended sediments effectively remove sperm from the water’s surface during coral spawning events, reducing the window for fertilisation with potential subsequent flow-on effects for recruitment. PMID:26659008

  11. Carbon content of sediments of small reservoirs

    SciTech Connect

    Ritchie, J.C. )

    1989-04-01

    Carbon content was measured in sediments deposited in 58 small reservoirs across the US. Reservoirs varied from 0.2 to 4,000 km{sup 2} in surface area. The carbon content of sediment ranged from 0.3 to 5.6 percent, with a mean of 1.9 {plus minus} 1.1 percent. No significant differences between the soil and sediment carbon content were found using a paired t-test or ANOVA. The carbon content of sediments in reservoirs was similar to the carbon content of surface soils in the watershed, except in watersheds with shrub or steppe (desert) vegetation. Based on the sediment accumulation rates measured in each reservoir, the calculated organic carbon accumulation rates among reservoirs ranged from 26 to 3,700 gC m{sup {minus}2} yr{sup {minus}1}, with a mean of 675 {plus minus} 739 gC m{sup {minus}2} yr{sup {minus}1}. The carbon content and accumulation rates were highest in sediments from grassland watersheds. High variability was found in carbon content, carbon accumulation, and sediment accumulation rates due to individual watershed and reservoir characteristics rather than to any broad physiographic patterns. The carbon accumulation rates in these reservoir sediments indicate that reservoir sediments could be a significant sink of organic carbon.

  12. Suspended sediments limit coral sperm availability.

    PubMed

    Ricardo, Gerard F; Jones, Ross J; Clode, Peta L; Humanes, Adriana; Negri, Andrew P

    2015-12-14

    Suspended sediment from dredging activities and natural resuspension events represent a risk to the reproductive processes of coral, and therefore the ongoing maintenance of reefal populations. To investigate the underlying mechanisms that could reduce the fertilisation success in turbid water, we conducted several experiments exposing gametes of the corals Acropora tenuis and A. millepora to two sediment types. Sperm limitation was identified in the presence of siliciclastic sediment (230 and ~700 mg L(-1)), with 2-37 fold more sperm required to achieve maximum fertilisation rates, when compared with sediment-free treatments. This effect was more pronounced at sub-optimum sperm concentrations. Considerable (>45%) decreases in sperm concentration at the water's surface was recorded in the presence of siliciclastic sediment and a >20% decrease for carbonate sediment. Electron microscopy then confirmed sediment entangled sperm and we propose entrapment and sinking is the primary mechanism reducing sperm available to the egg. Longer exposure to suspended sediments and gamete aging further decreased fertilisation success when compared with a shorter exposure. Collectively, these findings demonstrate that high concentrations of suspended sediments effectively remove sperm from the water's surface during coral spawning events, reducing the window for fertilisation with potential subsequent flow-on effects for recruitment.

  13. Sediment Sources in the Persian Gulf

    NASA Astrophysics Data System (ADS)

    Mahoutian, Mehrab

    2014-05-01

    Sediment Constituent Analysis is an effective tool for identifying sediment sources. Based on several sediment samples taken from different sites all over the Iranian coastlines, we have been able to show that an important portion of sediment on the beaches in the Persian Gulf is bio-clastic; that is, biologically created from the coral environment as well as other marine habitats. Unlike mineral (clastic) sediments, carbonate sediments are born not made. Furthermore, carbonate sand constituents are generally less durable than their quartz and mineral counterparts, and break down relatively quickly. Therefore, destruction of reefs and degradation of marine habitat are certain to reduce the sand supply to the shoreline in the Persian Gulf that is necessary to maintain beaches. Carbonate sands are also found on the coastline of the Oman Sea. One of the striking things about the sediments along the coastline of Iran is the high percentage of carbonate material. Molluscan debris is common, even ubiquitous. This reflects the populations living in the offshore waters. Some molluscs thrive in high-energy sandy environments, others like finer sediments. Some live at the surface, while some burrow down as much as a half-metre. A great deal of information can be gained from the study of the species of mollusk and their distribution in the sediments. This paper introduces a few case studies done in different parts of the Persian Gulf by using this method as a general assessment toolbox.

  14. Measuring the acute toxicity of estuarine sediments

    SciTech Connect

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

    1989-01-01

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

  15. Sediment reservoirs and sediment fluxes in high mountain environments: how does sediment move through the system at the decadal scale?

    NASA Astrophysics Data System (ADS)

    Micheletti, Natan; Lambiel, Christophe; Lane, Stuart N.

    2016-04-01

    Faced with rapid climate warming over recent decades, high mountain systems are likely to respond dramatically because of: (1) the vulnerability of permafrost, glacial and nival processes to temperature and precipitation changes; (2) the ample availability of unconsolidated, potentially mobile sediments left after deglaciation; and (3) steep slopes, that potentially aid sediment mobilization. We no surprisingly know little about these processes over the decadal scale because the geomorphic response is often complex, spatially and temporally, and there is little history of decadal scale measurement of these systems. In this paper, we focus upon a number of basins in the Southern Swiss Alps, with a wide range of primary sediment transfer mechanisms and altitude ranges up to 1,800 to 3,600 m asl. We are able to combine a set of unique data on: (1) erosion/deposition processes (derived from combined geomorphological maps and photogrammetrically-derived Digital Elevation Models); (2) sediment flux based upon tracking sediment using image correlation; (3) sediment connection quantified using a new approach to handle DEM noise; (4) changing stream sediment transport capacity derived from hydrodynamic modeling applied to long time series of river flow; and (5) sediment export measured at intakes flushed periodically as part of hydropower management. Results suggest a distinct landscape response to climatic forcing. A progressive acceleration of surface displacements for different landforms is observed throughout the last five decades. We observed that, with the beginning of a warmer period in the 1980s, glacier retreat and enhanced snowmelt caused water yield to increase considerably for various watersheds. This translates into enhancement of sediment transport capacities, which in combination with the intensification of landscape dynamics (greater erosion rates) explains the increase flushing frequency and hence sediment export registered in the basins. However, whilst

  16. Dating sediment in a fast sedimentation reservoir using 137Cs and 210Pb

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Over 10,000 reservoirs have been constructed in agricultural watersheds in the United States since the 1940s to control floods and sediments. Reservoir sedimentation records provide a unique opportunity to retrospectively study the effects of land use changes and climate variations on sediment produ...

  17. [Limnology of high mountain tropical lake, in Ecuador: characteristics of sediments and rate of sedimentation].

    PubMed

    Gunkel, Günter

    2003-06-01

    Equatorial high mountain lakes are a special type of lake occurring mainly in the South American Andes as well as in Central Africa and Asia. They occur at altitudes of a few thousand meters above sea level and are cold-water lakes (< 20 degrees C). Relatively little is known about them. A long-term limnological study was therefore undertaken at Lake San Pablo, Ecuador, to analyze the basic limnological processes of the lake, which has a tendency for eutrophication. Sediment quality of San Pablo Lake is given under consideration of horizontal and vertical distribution using sediment cores. Significance of sediments for eutrophication process of lakes is demonstrated using phosphorus concentration of sediments as well as the phosphorus retention capacity of the sediments by ratio Fe/P. Dating of the sediments is done using 137Cs and 210Pb, but the activity of 137Cs in the sediment was very low nearly at the detection level. Sedimentation rate is determined to be 3.5 mm/year and the sediment cores represent about 110 years. P concentration of the sediments is high (approximately 5 g/kg dry substance), and P retention capacity by Fe is insufficient (Fe/P = 4). The sediment quality did not change significantly during the past decades, and the trophic state of San Pablo Lake was already less or more eutrophic 110 years ago. The contamination of the lake sediments by heavy metals is insignificant.

  18. Sedimentation Velocity: A Classical Perspective.

    PubMed

    Correia, John J; Stafford, Walter F

    2015-01-01

    Here we give an overview of the history of sedimentation velocity analysis focusing on seminal and fundamental contributions that derived from early ultracentrifugation studies. We introduce the concepts of nonequilibrium thermodynamics and outline the derivation of the Svedberg and the Lamm equations and the requirements for including both hydrodynamic and thermodynamic nonideality. We introduce the phenomenological equations for coupled flows as developed from the principles of nonequilibrium or irreversible thermodynamics and derive a form of the Lamm equation that incorporates cross-diffusion coefficients and coupled gradient terms. We give an historical overview of solutions to the Lamm equation including Fujita-MacCosham solutions and Claverie finite-element numerical solutions and discuss the software that have implemented these solutions. We discuss the three major optical systems (absorbance, interference, and fluorescence) and recently developed multiwavelength systems. We also suggest a number of experimental practices and guidelines for optimizing the determination of s and D and discuss the appropriate centerpiece components and their utility. This chapter complements other recent reviews submitted by the authors (Correia, Lyons, Sherwood, & Stafford, 2015; Stafford, 2015) and should be considered an effort to revive the importance of irreversible thermodynamics in the understanding and analysis of sedimentation velocity ultracentrifugation data.

  19. Influence of wave and current flow on sediment-carrying capacity and sediment flux at the water-sediment interface.

    PubMed

    Zheng, Jun; Li, Ruijie; Yu, Yonghai; Suo, Anning

    2014-01-01

    In nearshore waters, spatial and temporal scales of waves, tidal currents, and circulation patterns vary greatly. It is, therefore, difficult to combine these factors' effects when trying to predict sediment transport processes. This paper proposes the concept of significant wave velocity, which combines the effects of waves, tides, and ocean currents using the horizontal kinetic energy superposition principle. Through a comparison of the relationship between shear stress at the water-sediment interface and sediment-carrying capacity, assuming equilibrium sediment flux, a new formula for sediment-carrying capacity, which incorporates the concept of significant wave velocities, is derived. Sediment-carrying capacity is a function of the critical velocity, which increases with water depth and decreases with increasing relative roughness of the sea bed. Finally, data from field observation stations and simulations are used to test the proposed formula. The results show that the new formula is in good agreement with both field and simulation data. This new formula for sediment-carrying capacity can be used to simulate nearshore sediment transport.

  20. Suspended sediment yield in Texas watersheds

    NASA Astrophysics Data System (ADS)

    Coonrod, Julia Ellen Allred

    The Texas Water Development Board collected suspended sediment samples across the state of Texas for approximately 60 years. Until this research, no comprehensive analysis of the data had been conducted. This study compiles the suspended sediment data along with corresponding streamflow and rainfall. GIS programs are developed which characterize watersheds corresponding to the sediment gauging stations. The watersheds are characterized according to topography, climate, soils, and land use. All of the data is combined to form several SAS data sets which can subsequently be analyzed using regression. Annual data for all of the stations across the state are classified temporally and spatially to determine trends in the sediment yield. In general, the suspended sediment load increases with increasing runoff but no correlation exists with rainfall. However, the annual average rainfall can be used to classify the watersheds according to climate, which improves the correlation between sediment load and runoff. The watersheds with no dams have higher sediment loads than watersheds with dams. Dams in the drier parts of Texas reduce the sediment load more than dams in the wetter part of the state. Sediment rating curves are developed separately for each basin in Texas. All but one of the curves fall into a band which varies by about two orders of magnitude. The study analyzes daily time series data for the Lavaca River near Edna station. USGS data are used to improve the sediment rating curve by the addition of physically related variables and interaction terms. The model can explain an additional 41% of the variability in sediment concentration compared to a simple bivariate regression of sediment load and flow. The TWDB daily data for the Lavaca River near Edna station are used to quantify temporal trends. There is a high correlation between sediment load and flowrate for the Lavaca River. The correlation can be improved by considering a flow-squared term and by

  1. Accounting for Long Term Sediment Storage in a Watershed Scale Numerical Model for Suspended Sediment Routing

    NASA Astrophysics Data System (ADS)

    Keeler, J. J.; Pizzuto, J. E.; Skalak, K.; Karwan, D. L.; Benthem, A.; Ackerman, T. R.

    2015-12-01

    Quantifying the delivery of suspended sediment from upland sources to downstream receiving waters is important for watershed management, but current routing models fail to accurately represent lag times in delivery resulting from sediment storage. In this study, we route suspended sediment tagged by a characteristic tracer using a 1-dimensional model that implicitly includes storage and remobilization processes and timescales. From an input location where tagged sediment is added, the model advects suspended sediment downstream at the velocity of the stream (adjusted for the intermittency of transport events). Deposition rates are specified by the fraction of the suspended load stored per kilometer of downstream transport (presumably available from a sediment budget). Tagged sediment leaving storage is evaluated from a convolution equation based on the probability distribution function (pdf) of sediment storage waiting times; this approach avoids the difficulty of accurately representing complex processes of sediment remobilization from floodplain and other deposits. To illustrate the role of storage on sediment delivery, we compare exponential and bounded power-law waiting time pdfs with identical means of 94 years. In both cases, the median travel time for sediment to reach the depocenter in fluvial systems less than 40km long is governed by in-channel transport and is unaffected by sediment storage. As the channel length increases, however, the median sediment travel time reflects storage rather than in-channel transport; travel times do not vary significantly between the two different waiting time functions. At distances of 50, 100, and 200 km, the median travel time for suspended sediment is 36, 136, and 325 years, orders of magnitude slower than travel times associated with in-channel transport. These computations demonstrate that storage can be neglected for short rivers, but for longer systems, storage controls the delivery of suspended sediment.

  2. Calibration of biological lake sediment records: Tracing diatom assemblages through the water column into the sediment

    NASA Astrophysics Data System (ADS)

    Maier, Dominique; Gälman, Veronika; Bigler, Christian; Renberg, Ingemar

    2013-04-01

    Paleolimnological studies rely on sediment cores taken from the deepest point of a lake. The deposited sediment and its embedded biological record are expected to be chronological and to display the lakes ecological past. Therefore many studies use micropalaeontological approaches, since, e. g., unicellular organisms like diatoms are directly dependent on habitat changes and thus mirror the prevailing weather conditions. In this study we combine a set of diatom samples from freeze cores of a varved sediment, a sediment trap and bi-weekly plankton survey data with environmental data to calibrate the biological sediment record of a lake. The annually laminated sediment of the boreal forest lake Nylandssjön in northern Sweden provides a very high temporal resolution, which allows us, even on a seasonal scale, a gapless comparison between in situ production and the sediment deposition. Analysis of the diatom assemblages through the water column into the sediment is expected to reveal quantitative and qualitative miss match in deposition, resuspension, seasonal and interannual delays caused by physical events or autochtonous interactions such as grazing in the water column. The overall comparison of the ten year plankton net record and the corresponding sediment trap samples reveals large shifts from season to season but also from year to year. The sediment trap diatom record indicates comparable abundance patterns for the main taxa (Asterionella formosa and Tabellaria flocculosa). Peaks and seasonal shifts are less pronounced in the sediment trap compared to the plankton data. An overall difficulty lies in the comparison of volumes of water and sediment, concentrations and fluxes, which needs to be solved. However, subsequent comparison with the sediment diatom assemblage is expected to lead us to understand interannual taphonomic processes affecting diatom records within ten years in the naturally formed sediment layers. More importantly we will be able to discover

  3. Variability of in situ sediment strength and pore pressure behavior of tidal estuary surface sediments

    NASA Astrophysics Data System (ADS)

    Lucking, Greg; Stark, Nina; Lippmann, Thomas; Smyth, Stephen

    2017-01-01

    Tidal estuaries feature spatially and temporally varying sediment dynamics and characteristics. Particularly, the variability of geotechnical sediment parameters is still poorly understood, limiting the prediction of long-term sediment stability and dynamics. This paper presents results from an in situ investigation of surficial sediments (≤50 cm) in a tidal estuary in New Hampshire (USA), using a portable free fall penetrometer. The aim is to investigate variations in sediment strength and pore pressure behavior with regard to sediment type and seabed morphology. The study also provides a detailed analysis of high velocity impact pore pressure data to derive information about sediment type and permeability. The penetrometer was deployed 227 times, and the findings are correlated to 78 sediment samples. Differences in sediment strength and type were found when transitioning from tidal flats to the deeper channels. Finer-grained sediments located predominantly on the tidal flats appeared well consolidated with noticeable and spatially consistent sediment strength (reflected in an estimate of quasi-static bearing capacity qsbcmax 10 kPa). Sediments with higher sand content (>75%) showed more variations in strength relating to differences in gradation, and likely represent loose and poorly consolidated sands (qsbcmax 10-55 kPa). The rate at which the recorded excess pore pressures approached equilibrium after penetration was classified and related to sediment type. The data indicate that the development of excess pore pressures upon impact and during penetration may provide additional insight into the nature and layering of bed material, such as identifying a desiccated or over-consolidated dilative surficial layer. In summary, with varying sediment grain size distributions, bulk densities and morphology, sediment strength and pore pressure behavior can vary significantly within a tidal estuary.

  4. Toutle/Cowlitz River Sediment Budget

    DTIC Science & Technology

    2010-05-18

    during the post 1998 period when spillway flows were supplying significantly more sediment to the downstream channel system, the specific gage... flows began permanently passing through the spillway . For the past 10 years sediment moving through the spillway of the SRS has contributed to...97 Figure 4.43 Cowlitz deposition for period prior to SRS filling to spillway

  5. Mathematical Model of Estuarial Sediment Transport.

    DTIC Science & Technology

    1977-10-01

    NUMBERS» Contract No. ^Ar DACW39-75-C-0080 ^^ 9. PERFORMING ORGANIZATION NAME AND ADDRESS Department of Civil Engineering...The original model, SEDIMENT I, was verified by comparison with measurements in a recirculating flume. The modified model, SEDIMENT II, developed for... organic matter from contiguous drainage areas, and waste materials. Clay minerals are hydrated aluminum silicates in a layer lattice crystal

  6. Field methods for measurement of fluvial sediment

    USGS Publications Warehouse

    Edwards, Thomas K.; Glysson, G. Douglas

    1999-01-01

    This chapter describes equipment and procedures for collection and measurement of fluvial sediment. The complexity of the hydrologic and physical environments and man's ever-increasing data needs make it essential for those responsible for the collection of sediment data to be aware of basic concepts involved in processes of erosion, transport, deposition of sediment, and equipment and procedures necessary to representatively collect sediment data. In addition to an introduction, the chapter has two major sections. The 'Sediment-Sampling Equipment' section encompasses discussions of characteristics and limitations of various models of depth- and point-integrating samplers, single-stage samplers, bed-material samplers, bedload samplers, automatic pumping samplers, and support equipment. The 'Sediment-Sampling Techniques'` section includes discussions of representative sampling criteria, characteristics of sampling sites, equipment selection relative to the sampling conditions and needs, depth and point-integration techniques, surface and dip sampling, determination of transit rates, sampling programs and related data, cold-weather sampling, bed-material and bedload sampling, measuring total sediment discharge, and measuring reservoir sedimentation rates.

  7. MISFIT BETWEEN SEDIMENT TOXICITY AND CHEMISTRY

    EPA Science Inventory

    In the United States, the EPA EMAP-Estuaries Program and the NOAA Bioeffects Surveys provide large data sets with which to test prosed relationships between sediment chemistry and toxicity. The conclusion is that no chemical measurement reliably predicts sediment toxicity. These ...

  8. Developing a biomonitoring tool for fine sediment

    NASA Astrophysics Data System (ADS)

    Turley, Matt; Bilotta, Gary; Brazier, Richard; Extence, Chris

    2014-05-01

    Sediment is an essential component of freshwater ecosystems; however anthropogenic activities can lead to elevated sediment delivery which can impact on the physical, chemical and biological characteristics of these ecosystems. Ultimately, this can result in a loss of ecosystem services worth more than 1.7 trillion per annum. As such it is important that sediment, which is one of the most commonly attributed causes of water quality impairment globally, is managed in order to minimise these impacts. The current EU environmental quality standard for sediment (monitored in the form of suspended solids) is 25 mg L-1 for all environments. It is widely recognised that this standard is unsuitable and not ecologically relevant. Furthermore, it requires a substantial resource investment to monitor sediment in this form as part of national and international water resource legislation. In recognition of this the development of sediment-specific biomonitoring tools is receiving increasing attention. The Proportion of Sediment-Sensitive Invertebrates (PSI) index is one such tool that is designed to indicate levels of fine sediment (

  9. An introduction to carbonate sediments and rocks

    SciTech Connect

    Scoffin, T.P.

    1986-01-01

    This book provides an approach to the study of carbonate sediments and sedimentary rocks. Topics covered include the following: nature and origins of common carbonate grains; processes of sedimentation; the growth and structure of coral reefs; distribution of modern marine carbonates; diagenesis; classification of limestone; facies models and sequences in ancient limestone; economic aspects; and field and laboratory techniques.

  10. Mercury-contaminated sediments affect amphipod feeding.

    PubMed

    Bundschuh, Mirco; Zubrod, Jochen P; Seitz, Frank; Newman, Michael C; Schulz, Ralf

    2011-04-01

    A 125-mile reach of the South River, Virginia, was contaminated with mercury during the first half of the 20th century. As increased concentrations of mercury have persisted, researchers have carefully studied its distribution in the river biota and estimated associated risks. The present study evaluated the influence of mercury on feeding rate and uptake by the amphipod Hyalella azteca. The test organisms were exposed for 7 days with leaf discs to reference and contaminated field sediment during the preliminary experiment and additionally to Sedimite (a commercial mercury-sequestering agent) amended sediments during the final experiment. The preliminary experiment demonstrated a decreased feeding rate (approximately 35%) of H. azteca in sediment from a contaminated site relative to sediment from a reference site. The test design of the final experiment took advantage of the knowledge gained in the preliminary experiment by increasing the number of replicates, which decreased the type II error rate. First, the results of the final experiment confirmed the results of the preliminary experiment by again demonstrating differences in the feeding rate of approximately 35% between reference and contaminated sediment. Second, the results indicated a lower feeding rate in reference sediment in the presence of Sedimite. Third, an opposite tendency, although not significant, was apparent for Sedimite-amended contaminated sediment. Thus, Sedimite appears to decrease sediment quality, whereas this conclusion is based on the feeding rate of H. azteca. However, Sedimite and its value as a mercury-sequestering agent requires further evaluation.

  11. Sediment and phosphorus transport in irrigation furrows.

    PubMed

    Bjorneberg, D L; Westermann, D T; Aase, J K; Clemmens, A J; Strelkoff, T S

    2006-01-01

    Sediment and phosphorus (P) in agricultural runoff can impair water quality in streams, lakes, and rivers. We studied the factors affecting P transfer and transport in irrigated furrows in six freshly tilled fallow fields, 110 to 180 m long with 0.007 to 0.012 m m-1 slopes without the interference of raindrops or sheet flow that occur during natural or simulated rain. The soil on all fields was Portneuf silt loam (coarse-silty, mixed, superactive, mesic Durinodic Xeric Haplocalcids). Flow rate, sediment concentration, and P concentrations were monitored at four, equally spaced locations in each furrow. Flow rate decreased with distance down the furrow as water infiltrated. Sediment concentration varied with distance and time with no set pattern. Total P concentrations related directly to sediment concentrations (r2=0.75) because typically >90% of the transported P was particulate P, emphasizing the need to control erosion to reduce P loss. Dissolved reactive phosphorus (DRP) concentrations decreased with time at a specific furrow site but increased with distance down the furrow as contact time with soil and suspended sediment increased. The DRP concentration correlated better with sediment concentration than extractable furrow soil P concentration. However, suspended sediment concentration tended to not affect DRP concentration later in the irrigation (>2 h). These results indicate that the effects of soil P can be overshadowed by differences in flow hydraulics, suspended sediment loads, and non-equilibrium conditions.

  12. Laboratory theory and methods for sediment analysis

    USGS Publications Warehouse

    Guy, Harold P.

    1969-01-01

    The diverse character of fluvial sediments makes the choice of laboratory analysis somewhat arbitrary and the pressing of sediment samples difficult. This report presents some theories and methods used by the Water Resources Division for analysis of fluvial sediments to determine the concentration of suspended-sediment samples and the particle-size distribution of both suspended-sediment and bed-material samples. Other analyses related to these determinations may include particle shape, mineral content, and specific gravity, the organic matter and dissolved solids of samples, and the specific weight of soils. The merits and techniques of both the evaporation and filtration methods for concentration analysis are discussed. Methods used for particle-size analysis of suspended-sediment samples may include the sieve pipet, the VA tube-pipet, or the BW tube-VA tube depending on the equipment available, the concentration and approximate size of sediment in the sample, and the settling medium used. The choice of method for most bed-material samples is usually limited to procedures suitable for sand or to some type of visual analysis for large sizes. Several tested forms are presented to help insure a well-ordered system in the laboratory to handle the samples, to help determine the kind of analysis required for each, to conduct the required processes, and to assist in the required computations. Use of the manual should further 'standardize' methods of fluvial sediment analysis among the many laboratories and thereby help to achieve uniformity and precision of the data.

  13. FIELD VALIDATION OF SEDIMENT TIE METHODS

    EPA Science Inventory

    Sediment toxicity is a widely recognized problem in many regions of the world. Frequently, however, the cause of toxicity is not known. The ability to identify the cause(s) of toxicity in sediments allows managers to determine sources of continuing contamination to support sele...

  14. Sediment Source Tracking in the Georgia Piedmont

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Preliminary results on the source of suspended sediment in a southern Piedmont stream are presented. Nuclear fallout radionuclide 137Cs and three other natural tracers were used to estimate the relative contribution of bank and upland sediment sources. Tracer concentrations were determined in potent...

  15. Phytoplankton and sediments in Yellow Sea

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Sediment and phytoplankton cloud the waters of the Yellow Sea in this true-color MODIS image acquired March 18, 2002. The swirls of sediment appear as a murky brownish blue color, while the phytoplankton are purely blue green and are concentrated around the small island in the lower right corner of the image.

  16. Mean sediment residence time in barchan dunes

    NASA Astrophysics Data System (ADS)

    Zhang, D.; Yang, X.; Rozier, O.; Narteau, C.

    2014-03-01

    When a barchan dune migrates, the sediment trapped on its lee side is later mobilized when exposed on the stoss side. Then sand grains may undergo many dune turnover cycles before their ejection along the horns, but the amount of time a sand grain contributes to the dune morphodynamics remains unknown. To estimate such a residence time, we analyze sediment particle motions in steady state barchans by tracking individual cells of a 3-D cellular automaton dune model. The overall sediment flux may be decomposed into advective and dispersive fluxes to estimate the relative contribution of the underlying physical processes to the barchan shape. The net lateral sediment transport from the center to the horns indicates that dispersion on the stoss slope is more efficient than the convergent sediment fluxes associated with avalanches on the lee slope. The combined effect of these two antagonistic dispersive processes restricts the lateral mixing of sediment particles in the central region of barchans. Then, for different flow strengths and dune sizes, we find that the mean residence time of sediment particles in barchans is equal to the surface of the central longitudinal dune slices divided by the input sand flux. We infer that this central slice contains most of the relevant information about barchan morphodynamics. Finally, we initiate a discussion about sediment transport and memory in the presence of bed forms using the advantages of the particle tracking technique.

  17. Climate variations, soil conservation and reservoir sedimentation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The integrated effects of soil conservation and a wetter climate on reservoir sedimentation were investigated for the Fort Cobb Reservoir watershed in west-central Oklahoma. A 12% wetter climate since the mid-1980s led to an increase in soil erosion and downstream sediment yield that offset the redu...

  18. Seasonal sediment and nutrients transport patterns

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It is essential to understand sediment and nutrient sources and their spatial and temporal patterns in order to design effective mitigation strategies. However, long-term data sets to determine sediment and nutrient loadings are scarce and expensive to collect. The goal of this study was to determin...

  19. Landscape self organisation: Modelling Sediment trains

    NASA Astrophysics Data System (ADS)

    Schoorl, J. M.; Temme, A. J. A. M.; Veldkamp, A.

    2012-04-01

    Rivers tend to develop towards an equilibrium length profile, independently of exogenous factors. In general, although still under debate, this so-called self-organisation is assumed to be caused by simple feedbacks between sedimentation and erosion. Erosion correlates positively with gradient and discharge and sedimentation negatively. With the LAPSUS model, which was run for the catchment of the Sabinal, a small river in the South of Spain, this interplay of erosion and sedimentation results in sediment pulses (sequences of incision and sedimentation through time). These pulses are visualised in a short movie ( see http://www.youtube.com/watch?v=V5LDUMvYZxU). In this case the LAPSUS model run did not take climate, base level nor tectonics into account. Therefore, these pulses can be considered independent of them. Furthermore, different scenarios show that the existence of the pulses is independent of precipitation, erodibility and sedimentation rate, although they control the number and shape of the pulses. A fieldwork check showed the plausibility of the occurrence of these sediment pulses. We conclude that the pulses as modelled with LAPSUS are indeed the consequence of the feedbacks between erosion and sedimentation and are not depending on exogenous factors. Keywords: Landscape self-organisation, Erosion, Deposition, LAPSUS, Modelling

  20. Fine-Sediment Loadings to Lake Tahoe

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Over the past 35 years, a trend of decreasing water clarity has been documented in Lake Tahoe, attributable in part to the delivery of fine-grained sediments emanating from upland and channel sources. The overall objective of the research reported here was to determine the amount of fine sediment de...

  1. Extrapolation of Biota-sediment Accumulation Factors

    EPA Science Inventory

    When assessing risks at sites with contaminated sediments, risk assessors need to estimate residues in fish and other aquatic biota based upon the levels of contaminants in the sediments. Unfortunately, risk assessors are often challenged by data limitations, i.e., i) contaminan...

  2. Deriving sediment Interstitial Water Remediation Goals ...

    EPA Pesticide Factsheets

    Background/Objectives. Passive sampling is becoming a frequently used measurement technique at Superfund sites with contaminated sediments. Passive sampling measures the concentrations of freely dissolved chemicals (Cfrees) in the sediment interstitial water. The freely dissolved chemical is a good surrogate for and a very practical means for estimating the concentrations of bioavailable chemical in the sediments. Building from this approach, a methodology is proposed to derive sediment Interstitial Water Remediation Goals (IWRGs) for the protection of benthic organisms from direct toxicity using Cfrees measured with passive sampling.Approach/Activities. In the early 2000s, EPA developed and released Equilibrium Partitioning Sediment Benchmarks (ESBs) for a series of chemicals. ESBs are intended to be chemical concentrations below which unacceptable toxicity to benthic organisms does not occur. The ESBs (expressed with the units of ug/g OC) were derived using the equations:ESB= K_OC×FCV where K_OC=0.00028+0.983K_OWThe KOC is the organic carbon normalized sediment-water chemical partition coefficient, FCV is the Final Chronic Value from EPA’s ambient water quality criteria for the protection of aquatic life, and KOW is the n-octanol/water partition coefficient for the chemical. At a specific site, the remedial goal (CS:ESB µg/kg-dw) in sediment are then derived using the site-specific fraction of organic carbon in the sediment (fOC:SS) at the site:C_

  3. Radioiodide sorption to sediment minerals

    SciTech Connect

    Kaplan, D.I.; Serne, R.J.; Parker, K.E.; Kutnyakov, I.V.

    1999-07-01

    Laboratory studies were conducted to quantify and understand the processes by which iodide (I{sup {minus}}) sorbs to minerals found in subsurface arid sediments. Little or no I{sup {minus}} sorbed to montmorillonite (K{sub d} = {minus}0.42 {+-} 0.08 mL/g), quartz (K{sub d} = 0.04 {+-} 0.02 mL/g), vermiculite (K{sub d} = 0.56 {+-} 0.21 mL/g), calcite (K{sub d} = 0.04 {+-} 0.01 mL/g), goethite (K{sub d} = 0.10 {+-} 0.03 mL/g), or chlorite (K{sub d} = {minus}0.22 {+-} 0.06 mL/g). A significant amount of I{sup {minus}} sorbed to illite (K{sub d} = 15.14 {+-} 2.84 mL/g). Upon treating the iodide-laden illite with dissolved F{sup {minus}}, Cl{sup {minus}}, Br{sup {minus}}, or {sup 127}I{sup {minus}}, desorption (or isotopic exchange in the case of {sup 127}I) removed, respectively, 43 {+-} 3%, 45 {+-} 0%, 52 {+-} 3, and 83 {+-} 1% of the I{sup {minus}} originally adsorbed to the illite. The fact that such large amounts of I{sup {minus}} could be desorbed suggests that the I{sup {minus}} was weakly adsorbed, and not chemically bonded to a soft metal, such as mercury or silver, that may have existed in the illite structure as trace impurities. Finally, I{sup {minus}} sorption to illite was strongly pH-dependent; the K{sub d} values decreased from 46 to 22 mL/g as the pH values increased from 3.6 to 9.4. Importantly, I{sup {minus}} sorbed to illite even under alkaline conditions. Together, these experiments suggest that illite removed I{sup {minus}} from the aqueous phase predominantly by reversible physical adsorption to the pH-dependent edge sites. Illites may constitute a substantial proportion of the clay-size fraction of many arid sediments and therefore may play an important role in retarding I{sup {minus}} movement in these sediments.

  4. 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...

  5. FIELD VALIDATION OF SEDIMENT TOXCITY IDENTIFCATION AND EVALUATION METHODS

    EPA Science Inventory

    Sediment Toxicity Identification and Evaluation (TIE) methods have been developed for both porewaters and whole sediments. These relatively simple laboratory methods are designed to identify specific toxicants or classes of toxicants in sediments; however, the question of whethe...

  6. Sediment chemoautotrophy in the coastal ocean

    NASA Astrophysics Data System (ADS)

    Vasquez-Cardenas, Diana; Meysman, Filip J. R.; van Breugel, Peter; Boschker, Henricus T. S.

    2016-04-01

    A key process in the biogeochemistry of coastal sediments is the reoxidation of reduced intermediates formed during anaerobic mineralization which in part is performed by chemoautotrophic micro-organisms. These microbes fix inorganic carbon using the energy derived from reoxidation reactions and in doing so can fix up to 32% of the CO2 released by mineralization. However the importance and distribution of chemoautotrophy has not been systematically investigated in these environments. To address these issues we surveyed nine coastal sediments by means of bacterial biomarker analysis (phospholipid derived fatty acids) combined with stable isotope probing (13C-bicarbonate) which resulted in an almost doubling of the number of observations on coastal sedimentary chemoautotrophy. Firstly, sediment chemoautotrophy rates from this study and rates compiled from literature (0.07 to 36 mmol C m-2 d-1) showed a power-law relation with benthic oxygen uptake (3.4 to 192 mmol O2 m-2 d-1). Benthic oxygen uptake was used as a proxy for carbon mineralization to calculate the ratio of the CO2 fixed by chemoautotrophy over the total CO2 released through mineralization. This CO2 efficiency was 3% in continental shelf, 9% in nearshore and 21% in salt marsh sediments. These results suggest that chemoautotrophy plays an important role in C-cycling in reactive intertidal sediments such as salt marshes rather than in the organic-poor, permeable continental shelf sediments. Globally in the coastal ocean our empirical results show that chemoautotrophy contributes ˜0.05 Pg C y-1 which is four times less than previous estimates. Secondly, five coastal sediment regimes were linked to the depth-distribution of chemoautotrophy: 1) permeable sediments dominated by advective porewater transport, 2) bioturbated sediments, and cohesive sediments dominated by diffusive porewater transport characterized by either 3) canonical sulfur oxidation, 4) nitrate-storing Beggiatoa, or 5) electrogenic sulfur

  7. Uncertainty in tsunami sediment transport modeling

    USGS Publications Warehouse

    Jaffe, Bruce E.; Goto, Kazuhisa; Sugawara, Daisuke; Gelfenbaum, Guy R.; La Selle, SeanPaul M.

    2016-01-01

    Erosion and deposition from tsunamis record information about tsunami hydrodynamics and size that can be interpreted to improve tsunami hazard assessment. We explore sources and methods for quantifying uncertainty in tsunami sediment transport modeling. Uncertainty varies with tsunami, study site, available input data, sediment grain size, and model. Although uncertainty has the potential to be large, published case studies indicate that both forward and inverse tsunami sediment transport models perform well enough to be useful for deciphering tsunami characteristics, including size, from deposits. New techniques for quantifying uncertainty, such as Ensemble Kalman Filtering inversion, and more rigorous reporting of uncertainties will advance the science of tsunami sediment transport modeling. Uncertainty may be decreased with additional laboratory studies that increase our understanding of the semi-empirical parameters and physics of tsunami sediment transport, standardized benchmark tests to assess model performance, and development of hybrid modeling approaches to exploit the strengths of forward and inverse models.

  8. Concentration-dependent sedimentation of colloidal rods

    NASA Astrophysics Data System (ADS)

    Dogic, Z.; Philipse, A. P.; Fraden, S.; Dhont, J. K. G.

    2000-11-01

    In this paper we first develop an approximate theory for the leading order concentration dependence of the sedimentation coefficient for rodlike colloids/polymers/macromolecules. To first order in volume fraction φ of rods, the sedimentation coefficient is written as 1+αφ. For large aspect ratios L/D (L is the rod length, D its thickness) α is found to vary like ∝(L/D)2/ln(L/D). This theoretical prediction is compared to experimental results. Then, experiments on fd virus are described, both in the isotropic and nematic phase. First-order in concentration results for this very long and thin (semiflexible) rod are in agreement with the above-mentioned theoretical prediction. Sedimentation profiles for the nematic phase show two sedimentation fronts. This result indicates that the nematic phase becomes unstable with the respect to isotropic phase during sedimentation.

  9. Deriving Sediment Interstitial Water Remediation Goals ...

    EPA Pesticide Factsheets

    This document contains a methodology for developing interstitial water remediation goals (IWRGs) for nonionic organic pollutants (toxicants) in sediments for the protection of benthic organisms. The document provides the basis for using the final chronic values (FCVs) from EPA’s aquatic water quality criteria (AWQC) for the protection of aquatic life to set the IWRGs for toxicants in sediments. Concentrations of the toxicants in the sediment interstitial water are measured using passive sampling. This document also discusses how to evaluate the consistency between passive sampling measurements and sediment toxicity test results. When these data are consistent, one can be reasonably assured that the causes of toxicity to benthic organisms in the sediment have been correctly identified and that the developed IWRGs for the toxicants will be protective of the benthic organisms at the site. The consistency evaluation is an important step in developing defensible IWRGs. To assist in developing defensible IWRGs.

  10. Snake and Columbia Rivers Sediment Sampling Project

    SciTech Connect

    Pinza, M. R.; Word, J. Q.; Barrows, E. S.; Mayhew, H. L.; Clark, D. R.

    1992-12-01

    The disposal of dredged material in water is defined as a discharge under Section 404 of the Clean Water Act and must be evaluated in accordance with US Environmental Protection Agency regulation 40 CFR 230. Because contaminant loads in the dredged sediment or resuspended sediment may affect water quality or contaminant loading, the US Army Corps of Engineers (USACE), Walla Walla District, has requested Battelle/Marine Sciences Laboratory to collect and chemically analyze sediment samples from areas that may be dredged near the Port Authority piers on the Snake and Columbia rivers. Sediment samples were also collected at River Mile (RM) stations along the Snake River that may undergo resuspension of sediment as a result of the drawdown. Chemical analysis included grain size, total organic carbon, total volatile solids, ammonia, phosphorus, sulfides, oil and grease, total petroleum hydrocarbons, metals, polynuclear aromatic hydrocarbons, pesticides, polychlorinated biphenyls, and 21 congeners of polychlorinated dibenzodioxins and dibenzofurans.

  11. Mixed sediment beach processes: Kachemak Bay, Alaska

    USGS Publications Warehouse

    Ruggiero, P.; Adams, P.N.; Warrick, J.A.

    2007-01-01

    Mixed sediment beaches are morphologically distinct from and more complex than either sand or gravel only beaches. Three digital imaging techniques are employed to quantify surficial grain size and bedload sediment transport rates along the mixed sediment beaches of Kachemak Bay, Alaska. Applying digital imaging procedures originally developed for quickly and efficiently quantifying grain sizes of sand to coarse sediment classes gives promising results. Hundreds of grain size estimates lead to a quantitative characterization of the region's sediment at a significant reduction in cost and time as compared to traditional techniques. Both the sand and coarse fractions on this megatidal beach mobilize into self-organized bedforms that migrate alongshore with a seasonally reflecting the temporal pattern of the alongshore component of wave power. In contrast, the gravel bedforms also migrate in the cross-shore without significant seasonally suggesting that swash asymmetry is sufficient to mobilize the gravel even during low energy summer conditions. ?? 2007 ASCE.

  12. A probabilistic sediment cascade model of sediment transfer in the Illgraben

    NASA Astrophysics Data System (ADS)

    Bennett, G. L.; Molnar, P.; McArdell, B. W.; Burlando, P.

    2014-02-01

    We present a probabilistic sediment cascade model to simulate sediment transfer in a mountain basin (Illgraben, Switzerland) where sediment is produced by hillslope landslides and rockfalls and exported out of the basin by debris flows and floods. The model conceptualizes the fluvial system as a spatially lumped cascade of connected reservoirs representing hillslope and channel storages where sediment goes through cycles of storage and remobilization by surface runoff. The model includes all relevant hydrological processes that lead to runoff formation in an Alpine basin, such as precipitation, snow accumulation, snowmelt, evapotranspiration, and soil water storage. Although the processes of sediment transfer and debris flow generation are described in a simplified manner, the model produces complex sediment discharge behavior which is driven by the availability of sediment and antecedent wetness conditions (system memory) as well as the triggering potential (climatic forcing). The observed probability distribution of debris flow volumes and their seasonality in 2000-2009 are reproduced. The stochasticity of hillslope sediment input is important for reproducing realistic sediment storage variability, although many details of the hillslope landslide triggering procedures are filtered out by the sediment transfer system. The model allows us to explicitly quantify the division into transport and supply-limited sediment discharge events. We show that debris flows may be generated for a wide range of rainfall intensities because of variable antecedent basin wetness and snowmelt contribution to runoff, which helps to understand the limitations of methods based on a single rainfall threshold for debris flow initiation in Alpine basins.

  13. Geochemistry of sediments in cores and sediment traps from Bear Lake, Utah and Idaho

    USGS Publications Warehouse

    Bischoff, James L.; Cummins, Kathleen; Shamp, Donald D.

    2005-01-01

    The present study of Bear Lake began in 1998. Initially, the study utilized sediments from three long cores (up to 5 m) previously collected in 1996 and short cores (up to 40 cm) collected in 1998. The short cores were specifically acquired to preserve the uppermost layers of sediment that may have been lost in the long cores. In addition, three arrays of sediment traps were deployed during the summer of 1998, and sediment from these traps was collected during the summers of 1999 and 2000 (see Dean and others, 2005, for core and sediment trap locations). The cores and sediment traps were sampled, and splits were distributed to various investigators for analyses of a wide variety of sediment parameters. The chemical composition of the acid-soluble component of the sediments is presented in this report. HCl or HNO3 treatment of the sediment quantitatively dissolves the authigenic component of the sediment, a component that includes carbonates, sulfates, and iron-mono sulfides. In the case of Bear Lake, CaCO3 is the major component of the sediment today and for most of the Holocene (Dean and others 2005). The chemical composition of the acid-soluble fraction gives important information on this component and, therefore, insight into the chemical conditions of the lake at the time of carbonate deposition.

  14. Sediment data sources and estimated annual suspended-sediment loads of rivers and streams in Colorado

    USGS Publications Warehouse

    Elliott, J.G.; DeFeyter, K.L.

    1986-01-01

    Sources of sediment data collected by several government agencies through water year 1984 are summarized for Colorado. The U.S. Geological Survey has collected suspended-sediment data at 243 sites; these data are stored in the U.S. Geological Survey 's water data storage and retrieval system. The U.S. Forest Service has collected suspended-sediment and bedload data at an additional 225 sites, and most of these data are stored in the U.S. Environmental Protection Agency 's water-quality-control information system. Additional unpublished sediment data are in the possession of the collecting entities. Annual suspended-sediment loads were computed for 133 U.S. Geological Survey sediment-data-collection sites using the daily mean water-discharge/sediment-transport-curve method. Sediment-transport curves were derived for each site by one of three techniques: (1) Least-squares linear regression of all pairs of suspended-sediment and corresponding water-discharge data, (2) least-squares linear regression of data sets subdivided on the basis of hydrograph season; and (3) graphical fit to a logarithm-logarithm plot of data. The curve-fitting technique used for each site depended on site-specific characteristics. Sediment-data sources and estimates of annual loads of suspended, bed, and total sediment from several other reports also are summarized. (USGS)

  15. Influence of sediment cohesion on deltaic shoreline dynamics and bulk sediment retention: A laboratory study

    NASA Astrophysics Data System (ADS)

    Straub, Kyle M.; Li, Qi; Benson, W. Matthew

    2015-11-01

    While boundary and forcing conditions influence the average location of a shoreline in deltaic systems, internal morphodynamics can drive high-magnitude deviations from the long-term trend. Here we explore the role of sediment cohesion on these morphodynamics using physical experiments. Specifically, we explore the role of sediment cohesion on the scales of autogenic shoreline transgressions and regressions. Results indicate that sediment cohesion enhances the time and space scales associated with autogenic cycles of channel formation, elongation, and abandonment. In systems with high sediment cohesion, this cycle can drive shoreline transgressions that produce flooding surfaces in the resulting stratigraphy which could be confused with surfaces produced by increases in sea level rise or subsidence rates. Enhanced channelization resulting from sediment cohesion also increases the pumping of fine-grained sediment into the marine realm, where it can bypass the delta foreset, thus decreasing total delta sediment retention rate.

  16. Martian sediments and sedimentary rocks

    NASA Technical Reports Server (NTRS)

    Markun, C. D.

    1988-01-01

    Martian sediments and sedimentary rocks, clastic and nonclastic, should represent a high priority target in any future return-sample mission. The discovery of such materials and their subsequent analysis in terrestrial laboratories, would greatly increase the understanding of the Martian paleoclimate. The formation of Martian clastic sedimentary rocks, under either present, low-pressure, xeric conditions or a postulated, high-pressure, hydric environment, depends upon the existence of a supply of particles, various cementing agents and depositional basins. A very high resolution (mm-cm range) photographic reconnaissance of these areas would produce a quantum jump in the understanding of Martian geological history. Sampling would be confined to more horizontal (recent) surfaces. Exploration techniques are suggested for various hypothetical Martian sedimentary rocks.

  17. Fluvial sediment flux to the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Gordeev, V. V.

    2006-10-01

    The paper presents an overview of recent publications on the fluvial suspended sediment flux to the Arctic Ocean. The total suspended matter exported from the Russian territory is 102 × 10 6 t/year and from the Canadian Arctic is 125 × 10 6 t/year. The total suspended matter (TSM) flux to the Arctic (227 × 10 6 t/year) is very low, only about 1% of the global flux. Mean concentrations of suspended matter and specific sediment discharge are approximately one order of magnitude lower than the global concentration. An analysis of the trends in the sediment loads based on records of up to 62 years in length shows decreases (Yenisey), increases (Kolyma) and stability (Ob). Among the reasons for the very low concentrations and fluxes of suspended sediment in the Arctic rivers are thin weathering crusts on the Arctic watersheds, low precipitation, extensive permafrost, low temperatures for most of the year, large areas of swamps and lakes and a low level of human activity. A stochastic sediment transport model by Morehead et al. [Morehead, M.D., Syvitski, J.P., Hutton, E.W., Peckham, S.D., 2003. Modeling the temporal variability in the flux of sediment from ungauged river basins. Glob. Planet. Change 39, 95-110] is applied to the Arctic rivers to estimate the sediment load increase should the surface temperature of the drainage basin increase. For every 2 °C of warming a 30% increase in the sediment flux could result and for each 20% increase in water discharge, a 10% increase in sediment load could follow. Based on this model, an increase of the sediment flux of six largest arctic rivers (Yenisey, Lena, Ob, Pechora, Kolyma and Severnaya Dvina) is predicted to range from 30% to 122% by 2100.

  18. Sediment dispersal in the northwestern Adriatic Sea

    USGS Publications Warehouse

    Harris, C.K.; Sherwood, C.R.; Signell, R.P.; Bever, A.J.; Warner, J.C.

    2008-01-01

    Sediment dispersal in the Adriatic Sea was evaluated using coupled three-dimensional circulation and sediment transport models, representing conditions from autumn 2002 through spring 2003. The calculations accounted for fluvial sources, resuspension by waves and currents, and suspended transport. Sediment fluxes peaked during southwestward Bora wind conditions that produced energetic waves and strengthened the Western Adriatic Coastal Current. Transport along the western Adriatic continental shelf was nearly always to the south, except during brief periods when northward Sirocco winds reduced the coastal current. Much of the modeled fluvial sediment deposition was near river mouths, such as the Po subaqueous delta. Nearly all Po sediment remained in the northern Adriatic. Material from rivers that drain the Apennine Mountains traveled farther before deposition than Po sediment, because it was modeled with a lower settling velocity. Fluvial sediment delivered to areas with high average bed shear stress was more highly dispersed than material delivered to more quiescent areas. Modeled depositional patterns were similar to observed patterns that have developed over longer timescales. Specifically, modeled Po sediment accumulation was thickest near the river mouth with a very thin deposit extending to the northeast, consistent with patterns of modern sediment texture in the northern Adriatic. Sediment resuspended from the bed and delivered by Apennine Rivers was preferentially deposited on the northern side of the Gargano Peninsula, in the location of thick Holocene accumulation. Deposition here was highest during Bora winds when convergences in current velocities and off-shelf flux enhanced delivery of material to the midshelf. Copyright 2008 by the American Geophysical Union.

  19. Assessing the potential toxicity of resuspended sediment

    SciTech Connect

    Bonnet, C.; Babut, M.; Ferard, J.F.; Martel, L.; Garric, J.

    2000-05-01

    Two moderately contaminated freshwater sediments (Sorel Harbour, St. Lawrence River, Canada) were subjected to a suspension event. The objective was to assess the environmental impact of the disposal of dredged material in water, in particular, the short-term effects of dumping on the water column and the long-term effects of dredged sediment deposits. In a series of microcosms, the sediments were left to stand for 25 d under flow-through conditions. In a second series of microcosms, sediments were vigorously suspended for 15 min before being left to settle and were submitted to the same treatment as reference sediments during the following 25 d. Physicochemical and biological parameters (Daphnia magna and Hydra attenuata survival) were measured in overlying water throughout the experiment. Sediment toxicity was assessed with Chironomus tentans and Hyalella azteca exposed to sediments collected at both the beginning and end of the 25-d period. Pore-water toxicity was evaluated with D. magna. During the suspension process, in the Sorel Harbour mixed sediment overlying water, the authors observed effects on H. attenuata survival and ammonia and metals (chromium, copper, and zinc) releases. Meanwhile, in reference (nonmixed) and mixed sediments as well as in associated pore waters, there were no significant chemical modifications no biological effects after the 25-d experiments. The developed approach, which attempts to simulate a dumping process, aims at allowing the assessment of the short- and long-term hazards resulting from a resuspension process in overlying water and in resettled sediments using both chemical and biological measurements.

  20. Interstitial brines in playa sediments

    USGS Publications Warehouse

    Jones, B.F.; Van Denburgh, A.S.; Truesdell, A.H.; Rettig, S.L.

    1969-01-01

    Study of several closed drainages in the Great Basin has shown that the interstitial solutions of shallow, fine-grained playa deposits store a large quantity of dissolved solids and are often more concentrated than associated lakes and ponds, except in peripheral zones of stream or ground-water inflow. These interstitial fluids, when compared with local runoff, impoundments, or spring waters, commonly have a distinctive ionic composition which sometimes cannot be explained by either simple mixing of surface and subsurface inflow or by evaporative concentration. At Abert Lake, Oregon, the interstitial solute concentrations increased with depth to values as much as five times greater than the lake, except where springs indicate significant ground-water input. Where Na+, Cl, and CO2 species constitute more than 90% of the solutes, Na+ Cl- ratios in the lake water are lower than in interstitial solutions of bottom cores and higher than in playa fluids. At the same time, Na+ K+ ratios are highest in the fluids of lake bottom muds and lowest in playa interstitials. In deeper playa profiles, interstitial Na+ Cl- tended to decrease with depth (5 ft. maximum). In the Abert Lake area, as in other parts of the western Great Basin, Na+ Cl- ratios are indicative of total CO2 in solution and the effects of organic decay in surficial sediments. These ratios, coupled with data on silica and bulk density, show that higher PCO2 accompanying decay promotes silicate dissolution and hydrogen ion exchange, stripping alkalis from sediment which had preferentially adsorbed K+ when entering the lake. On subsequent loss of pore fluid in the playa regime, silica initially released to solution in the lake environment is readsorbed on dissolution products. ?? 1969.

  1. Relationship of Bacterial Richness to Organic Degradation Rate and Sediment Age in Subseafloor Sediment

    PubMed Central

    Walsh, Emily A.; Kirkpatrick, John B.; Pockalny, Robert; Sauvage, Justine; Spivack, Arthur J.; Murray, Richard W.; Sogin, Mitchell L.

    2016-01-01

    ABSTRACT Subseafloor sediment hosts a large, taxonomically rich, and metabolically diverse microbial ecosystem. However, the factors that control microbial diversity in subseafloor sediment have rarely been explored. Here, we show that bacterial richness varies with organic degradation rate and sediment age. At three open-ocean sites (in the Bering Sea and equatorial Pacific) and one continental margin site (Indian Ocean), richness decreases exponentially with increasing sediment depth. The rate of decrease in richness with increasing depth varies from site to site. The vertical succession of predominant terminal electron acceptors correlates with abundance-weighted community composition but does not drive the vertical decrease in richness. Vertical patterns of richness at the open-ocean sites closely match organic degradation rates; both properties are highest near the seafloor and decline together as sediment depth increases. This relationship suggests that (i) total catabolic activity and/or electron donor diversity exerts a primary influence on bacterial richness in marine sediment and (ii) many bacterial taxa that are poorly adapted for subseafloor sedimentary conditions are degraded in the geologically young sediment, where respiration rates are high. Richness consistently takes a few hundred thousand years to decline from near-seafloor values to much lower values in deep anoxic subseafloor sediment, regardless of sedimentation rate, predominant terminal electron acceptor, or oceanographic context. IMPORTANCE Subseafloor sediment provides a wonderful opportunity to investigate the drivers of microbial diversity in communities that may have been isolated for millions of years. Our paper shows the impact of in situ conditions on bacterial community structure in subseafloor sediment. Specifically, it shows that bacterial richness in subseafloor sediment declines exponentially with sediment age, and in parallel with organic-fueled oxidation rate. This result

  2. Advancing knowledge gained from sediment budgets through sediment age dating and fingerprinting in small watersheds

    NASA Astrophysics Data System (ADS)

    Skalak, K.; Benthem, A.; Gellis, A.; Harvey, J. W.; Hupp, C. R.; Larsen, L.; Noe, G. B.; Pizzuto, J. E.; Schenk, E.

    2013-12-01

    Dynamics and long-term trajectories of fine sediment generally remain poorly quantified in rivers, which have implications for nutrient and contaminant transport and remediation strategies. Here we focus on two streams within the Chesapeake Bay watershed, Difficult Run and Accotink Creek. These streams have varying degrees of urbanization and diverse best management practices, making possible a comparison of sediment sources, sinks, and residence times to illuminate how land management impacts fine sediment transport. Bank erosion and floodplain accumulation in Difficult Run has been previously determined and is ongoing in Accotink Creek. Current work advances sediment budgets by quantifying the role of in-channel fine sediment storage in the bed and margins. To understand the relative storage timescales for various geomorphic features (floodplain, in-channel, etc.) and develop age distributions, sediment is dated using radionuclides of varying half-lives such as Pb-210, Cs-137, Be-7, bomb radiocarbon, and optically stimulated luminescence (OSL). To determine the source of sediment that is transported in suspension, sediment fingerprinting has been completed in Difficult Run and initiated in Accotink Creek. Furthermore, the present study furthers our understanding of fine sediment dynamics by fingerprinting sources of stored sediment and evaluating how they evolve over storm events and stream size. For this, we sampled sediment in storage zones before and after storm events of a specified magnitude to determine their chemical signatures with respect to various source-tracking elements and isotopes. This study represents the first such work to integrate sediment dating, sediment fingerprinting and an analysis of storage zones to understand fine sediment dynamics and long-term trajectories.

  3. Effects of tubificid bioturbation on pore structures in sediment and the migration of sediment particles.

    PubMed

    Li, Yaorui; Hua, Xiuyi; Zheng, Fang; Dong, Deming; Liang, Dapeng; Guo, Zhiyong

    2016-04-01

    In this study, the effects of tubificid bioturbation near the water-sediment interface on pore structures and the migration of sediment particles were evaluated using a series of simulations. In these experiments, the distribution and variation of the tubificid burrows and the macropores in the sediment were investigated by X-ray computed tomography (CT) and digital image collecting, without sampling or disturbing the sediment. The migration of the sediment particles was also determined using CT by adding BaSO4 microspheres to the sediment as a tracer. The effects of tubificid bioturbation on the distribution and migration of contaminants in the sediment were verified by adding Pb-containing sediment layers to the sediment. The results indicate that after the addition of the tubificids, both the burrows and the macropores in the sediments increased with time, and the rate of increase slowed gradually. With the increased worm density, the burrows and the pore structures also increased. The in-depth distribution of the burrows and macropores was determined by the settlement time of the worms: with the settlement time increasing from 3 to 19 days, the depth of the zone with the highest density of burrows and macropores increased from 0-30 to 30-50 mm and from 0-10 to 30-60 mm, respectively. The distribution of the burrows and macropores was closely related to the distribution of the tubificids. Thickening of the oxidized zones in the superficial sediments in the presence of tubificid bioturbation was also observed. The main action of tubificids on the sediment particles was the transport of particles from the inner sediment (especially in the range of 30-50 mm in depth) to the water-sediment interface. The migration of Pb in the contaminated sediment with tubificid bioturbation could be interpreted by the variation in the burrows and macropores and the migration of sediment particles. Both the formation and the variation in the burrows and macropores, as well as

  4. Quantity, composition, and source of sediment collected in sediment traps along the fringing coral reef off Molokai, Hawaii

    USGS Publications Warehouse

    Bothner, Michael H.; Reynolds, R.L.; Casso, M.A.; Storlazzi, C.D.; Field, M.E.

    2006-01-01

    Sediment traps were used to evaluate the frequency, cause, and relative intensity of sediment mobility/resuspension along the fringing coral reef off southern Molokai (February 2000–May 2002). Two storms with high rainfall, floods, and exceptionally high waves resulted in sediment collection rates > 1000 times higher than during non-storm periods, primarily because of sediment resuspension by waves. Based on quantity and composition of trapped sediment, floods recharged the reef flat with land-derived sediment, but had a low potential for burying coral on the fore reef when accompanied by high waves. The trapped sediments have low concentrations of anthropogenic metals. The magnetic properties of trapped sediment may provide information about the sources of land-derived sediment reaching the fore reef. The high trapping rate and low sediment cover indicate that coral surfaces on the fore reef are exposed to transient resuspended sediment, and that the traps do not measure net sediment accumulation on the reef surface.

  5. SANDS - Sediment Analysis Network for Decision Support

    NASA Astrophysics Data System (ADS)

    Hardin, D. M.; Hawkins, L.; He, M.; Ebersole, S.

    2010-12-01

    Since the year 2000, Eastern Louisiana, coastal Mississippi, Alabama, and the western Florida panhandle have been affected by 28 tropical storms, seven of which were hurricanes. These tropical cyclones have significantly altered normal coastal processes and characteristics in the Gulf region through sediment disturbance. Although tides, seasonality, and agricultural development influence suspended sediment and sediment deposition over periods of time, tropical storm activity has the capability of moving the largest sediment loads in the shortest periods of time for coastal areas. The SANDS project is also investigating the effects of sediment immersed oil from the Deepwater Horizon disaster in April 2010 which has the potential to resurface as a result of tropical storm activity. The importance of sediments upon water quality, coastal erosion, habitats and nutrients has made their study and monitoring vital to decision makers in the region. Currently agencies such as United States Army Corps of Engineers (USACE), NASA, and Geological Survey of Alabama (GSA) are employing a variety of in-situ and airborne based measurements to assess and monitor sediment loading and deposition. These methods provide highly accurate information but are limited in geographic range, are not continuous over a region and, in the case of airborne LIDAR are expensive and do not recur on a regular basis. Multi-temporal and multi-spectral satellite imagery that shows tropical-storm-induced suspended sediment and storm-surge sediment deposits can provide decision makers with immediate and long-term information about the impacts of tropical storms and hurricanes. It can also be valuable for those conducting research and for projects related to coastal issues such as recovery, planning, management, and mitigation. The Sediment Analysis Network for Decision Support has generated a number of decision support products derived from MODIS, Landsat and SeaWiFS instruments that potentially support

  6. Managing Fine Sediment in Regulated Rivers

    NASA Astrophysics Data System (ADS)

    Schmidt, J. C.

    2015-12-01

    A paradigm useful in managing dams and diversions is that the combined effects of changing flow regime and sediment supply perturb regulated rivers into sediment deficit or sediment surplus. In the U.S. Southwest, large dams constructed on interregional rivers typically create sediment deficit segments >100 km long. Further downstream, sediment surplus may occur if desert tributaries deliver sufficient amounts of fine sediment, such as parts of the Rio Grande, lower Green River, and Colorado River delta. Sediment surplus also occurs on most smaller regional rivers. The protocols for managing rivers perturbed into sediment deficit have been refined for the Colorado River downstream from Glen Canyon Dam but are nonetheless challenged by externally determined water-supply agreements that require annual water deliveries that sometimes occur when there has been little tributary resupply. Virtually all of the naturally supplied sand to the depleted, 100-km long Marble Canyon comes from the Paria River. The sand delivery rate since 2012 was sufficiently large to trigger short-duration controlled floods under the High Flow Experiment (HFE) Protocol. The sand mass balance of Marble Canyon since 2012 when the HFE Protocol was adopted was positive due to the combination of relatively large sand delivery from the Paria River and average total annual flows. Large total annual flows have the potential to export large amounts of sand and create a negative sand mass balance. Despite the challenge of managing a scarce and highly variable sand supply and occasional years of large reservoir releases, the long-term (2006-2015) sand mass balance for the upstream half of Marble Canyon is indeterminant and is positive for the downstream half of Marble Canyon. The apparent success of managing sand in Grand Canyon under deficit conditions suggests that fine sediment management protocols might be developed for other regulated rivers. Implementation would require establishment of networks of

  7. Using sediment 'fingerprints' to assess sediment-budget errors, north Halawa Valley, Oahu, Hawaii, 1991-92

    USGS Publications Warehouse

    Hill, B.R.; DeCarlo, E.H.; Fuller, C.C.; Wong, M.F.

    1998-01-01

    Reliable estimates of sediment-budget errors are important for interpreting sediment-budget results. Sediment-budget errors are commonly considered equal to sediment-budget imbalances, which may underestimate actual sediment-budget errors if they include compensating positive and negative errors. We modified the sediment 'fingerprinting' approach to qualitatively evaluate compensating errors in an annual (1991) fine (<63 ??m) sediment budget for the North Halawa Valley, a mountainous, forested drainage basin on the island of Oahu, Hawaii, during construction of a major highway. We measured concentrations of aeolian quartz and 137Cs in sediment sources and fluvial sediments, and combined concentrations of these aerosols with the sediment budget to construct aerosol budgets. Aerosol concentrations were independent of the sediment budget, hence aerosol budgets were less likely than sediment budgets to include compensating errors. Differences between sediment-budget and aerosol-budget imbalances therefore provide a measure of compensating errors in the sediment budget. The sediment-budget imbalance equalled 25% of the fluvial fine-sediment load. Aerosol-budget imbalances were equal to 19% of the fluvial 137Cs load and 34% of the fluval quartz load. The reasonably close agreement between sediment- and aerosol-budget imbalances indicates that compensating errors in the sediment budget were not large and that the sediment-budget imbalance as a reliable measure of sediment-budget error. We attribute at least one-third of the 1991 fluvial fine-sediment load to highway construction. Continued monitoring indicated that highway construction produced 90% of the fluvial fine-sediment load during 1992. Erosion of channel margins and attrition of coarse particles provided most of the fine sediment produced by natural processes. Hillslope processes contributed relatively minor amounts of sediment.

  8. Sediment characteristics and sedimentation rates in Lake Michie, Durham County, North Carolina, 1990-92

    USGS Publications Warehouse

    Weaver, J.C.

    1994-01-01

    A reservoir sedimentation study was conducted at 508-acre Lake Michie, a municipal water-supply reservoir in northeastern Durham County, North Carolina, during 1990-92. The effects of sedimentation in Lake Michie were investigated, and current and historical rates of sedimentation were evaluated. Particle-size distributions of lake-bottom sediment indicate that, overall, Lake Michie is rich in silt and clay. Nearly all sand is deposited in the upstream region of the lake, and its percentage in the sediment decreases to less than 2 percent in the lower half of the lake. The average specific weight of lake-bottom sediment in Lake Michie is 73.6 pounds per cubic foot. The dry-weight percentage of total organic carbon in lake-bottom sediment ranges from 1.1 to 3.8 percent. Corresponding carbon-nitrogen ratios range form 8.6 to 17.6. Correlation of the total organic carbon percentages with carbon-nitrogen ratios indicates that plant and leaf debris are the primary sources of organic material in Lake Michie. Sedimentation rates were computed using comparisons of bathymetric volumes. Comparing the current and previous bathymetric volumes, the net amount of sediment deposited (trapped) in Lake Michie during 1926-92 is estimated to be about 2,541 acre-feet or slightly more than 20 percent of the original storage volume computed in 1935. Currently (1992), the average sedimentation rate is 38 acre-feet per year, down from 45.1 acre-feet per year in 1935. To confirm the evidence that sedimentation rates have decreased at Lake Michie since its construction in 1926, sediment accretion rates were computed using radionuclide profiles of lake-bottom sediment. Sediment accretion rates estimated from radiochemical analyses of Cesium-137 and lead-210 and radionuclides in the lake-bottom sediment indicate that rates were higher in the lake?s early years prior to 1962. Estimated suspended-sediment yields for inflow and outflow sites during 1983-91 indicate a suspended-sediment trap

  9. Equilibrium Partitioning Sediment Benchmarks (ESBs) for the ...

    EPA Pesticide Factsheets

    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 accounts for the varying bioavailability of chemicals in different sediments and allows for the incorporation of the appropriate biological effects concentration. This provides for the derivation of benchmarks that are causally linked to the specific chemical, applicable across sediments, and appropriately protective of benthic organisms.  This equilibrium partitioning sediment benchmark (ESB) document was prepared by scientists from the Atlantic Ecology Division, Mid-Continent Ecology Division, and Western Ecology Division, the Office of Water, and private consultants. The document describes procedures to determine the interstitial water concentrations of nonionic organic chemicals in contaminated sediments. Based on these concentrations, guidance is provided on the derivation of toxic units to assess whether the sediments are likely to cause adverse effects to benthic organisms. The equilibrium partitioning (EqP) approach was chosen because it is based on the concentrations of chemical(s) that are known to be harmful and bioavailable in the environment.  This document, and five others published over the last nine years, will be useful for the Program Offices, including Superfund, a

  10. Dense colloidal fluids form denser amorphous sediments

    PubMed Central

    Liber, Shir R.; Borohovich, Shai; Butenko, Alexander V.; Schofield, Andrew B.; Sloutskin, Eli

    2013-01-01

    We relate, by simple analytical centrifugation experiments, the density of colloidal fluids with the nature of their randomly packed solid sediments. We demonstrate that the most dilute fluids of colloidal hard spheres form loosely packed sediments, where the volume fraction of the particles approaches in frictional systems the random loose packing limit, φRLP = 0.55. The dense fluids of the same spheres form denser sediments, approaching the so-called random close packing limit, φRCP = 0.64. Our experiments, where particle sedimentation in a centrifuge is sufficiently rapid to avoid crystallization, demonstrate that the density of the sediments varies monotonically with the volume fraction of the initial suspension. We reproduce our experimental data by simple computer simulations, where structural reorganizations are prohibited, such that the rate of sedimentation is irrelevant. This suggests that in colloidal systems, where viscous forces dominate, the structure of randomly close-packed and randomly loose-packed sediments is determined by the well-known structure of the initial fluids of simple hard spheres, provided that the crystallization is fully suppressed. PMID:23530198

  11. Global sediment fluxes during the last millennium

    NASA Astrophysics Data System (ADS)

    Naipal, Victoria; Reick, Christian; Van Oost, Kristof; Hoffmann, Thomas; Pongratz, Julia

    2016-04-01

    Soil redistribution plays an important role in the transport of carbon and nutrients between terrestrial ecosystems. However, quantification of soil redistribution and its effects on the global biogeochemical cycles is currently unknown. This study aims at developing new tools and methods to represent soil redistribution on a global scale, and contribute to the quantification of anthropogenic disturbances to the biogeochemical cycles. We present a new large-scale coarse resolution sediment budget model that can simulate spatial patterns and long-term trends in soil redistribution in floodplains and on hillslope, resulting from external forces such as climate and land use change. First, we validated the model for the Rhine catchment using observed Holocene sediment storage data and observed scaling behavior between sediment storage and catchment area. Then, we applied the model on 20 large river catchments globally, using climate and land cover data from the Max Planck Institute Earth System Model (MPI-ESM) for the last millennium (850 - 2005AD). We show that the model can reproduce current observed sediment yields if uncertainty in the observations is taken into account. Furthermore, we find that the change in erosion rates during the last millennium resulted in a significant increase in sediment storage for different global catchments. We identify land use change as the main driver behind this change in sediment storage. Finally, catchments characteristics, such as area and slope, play an important role in buffering or amplifying the effect of land use and other external forces on the change in erosion and sediment storage.

  12. Evaluation of sediment transport in steep channels combining sediment impact sensors, tracer stones and TLS

    NASA Astrophysics Data System (ADS)

    Harb, Gabriele; Schneider, Josef; Sass, Oliver; Stangl, Johannes

    2016-04-01

    Torrential floods combined with sediment transport presents major hazards to human life and infrastructure in alpine catchments. Despite the importance of sediment transport due to the large damage caused in case of flood events, we lack data on sediment movement and sediment transport rates in steep channels and torrents to improve the understanding of sediment transport processes in this areas. This paper presents an improved application of sediment impact sensors (SIS) integrated in a unique measurement system in an Alpine catchment in Austria consisting of meteorological stations, runoff gauges and tracer stones. In addition sediment availability, mobilization and accumulation have been mapped and quantified by means of terrestrial laser scanning (TLS) and structure from motion using unmanned aerial vehicles (UAVs). Additionally a numerical model was used to simulate the bed load transport rates in the torrent. This contribution focuses on field measurements of bed load transport rates in steep channels based on SIS data, tracer stone data, bed load measurements, precipitation and discharge data. The measurement data was compared to several sediment transport formulae for steep slopes and validated with the observed deposited amount of sediment in the sediment retention basin at the outlet of the catchment.

  13. Micro structure of gas-hydrate sediment: in situ sub-sampling from pressured sedimental samples

    NASA Astrophysics Data System (ADS)

    Jin, Y.; Konno, Y.; Yoneda, J.; Egawa, K.; Kida, M.; Ito, T.; Suzuki, K.; Nakatsuka, Y.; Nagao, J.

    2013-12-01

    Porosity of gas-hydrate bearing sediment is a key of gas production efficient from natural gas-hydrate reservoir. Developable natural gas-hydrates by conventional gas/oil production apparatus almost exist in unconsolidated sedimental layer. Because in situ evaluation of porosity with hydrate in pores is difficult, porosity values were discussed from hydrate bearing sediment quenched by liquid nitrogen. In the case of quenched sample, sand matrix in GH sediments could have been changed by freezing water in pores. Therefore, porosity data in previous reports may be over estimated comparing with nature of sediments at in situ condition. We developed in situ sub-sampling system for pressured natural gas-hydrate sediments. A small sedimental piece can be sampled from pressured gas hydrate sediments without pressure-release to atmosphere by using the our developed apparatus. In this presentation, we demonstrated sub-sampling from an artificial gas-hydrate sediment and measured micro-scale structure of the sub-sampled gas-hydrate sedimental piece. This work was supported by funding from the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) planned by the Ministry of Economy, Trade and Industry (METI), Japan.

  14. Site-specific sediment clean-up objectives developed by the sediment quality triad

    SciTech Connect

    Redman, S.; Janisch, T.

    1995-12-31

    Sediment chemistry, sediment toxicity, and benthic macroinvertebrate community data were collected and evaluated in concert (1) to characterize adverse effects of hydrocarbon and metal contaminants in the sediments of a small inlet of Superior Bay, Lake Superior and a tributary creek and (2) to derive numeric objectives for the clean up of this system. Sediments from reference locations and eight study sites were analyzed for a range of contaminants, including hydrocarbons (measured both as diesel range organics (DRO) and oil and grease), lead, chromium, and ammonia. A range of sediment toxicity was observed across the eight study sites using a variety of tests and endpoints: Hyalella azteca (10 day survival and growth), Chironomus tentans (10 day survival and growth), Ceriodaphnia dubia (48 hour survival), and Daphnia magna (48 hour survival and 10 day survival and reproduction). A range of alterations of the benthic macroinvertebrate community compared with communities from reference locations were observed. Benthic community alterations were summarized quantitatively by taxa richness and Shannon-Weiner mean diversity. Lowest effect levels determined through this study included 150 {micro}g/g dry sediment for DRO (as measured in this study) and 40 {micro}g/g dry sediment for lead. Effects thresholds determined through this study included 1,500 {micro}g/g dry sediment for DRO and 90 {micro}g/g dry sediment for lead. These levels and concentrations measured in relevant reference locations are being used to define objectives for sediment clean up in the inlet and creek.

  15. Assessing contamination in Great Lakes sediments using benthic invertebrate communities and the sediment quality triad approach

    USGS Publications Warehouse

    Canfield, Timothy J.; Dwyer, F. James; Fairchild, James F.; Haverland, Pamela S.; Ingersoll, Christopher G.; Kemble, Nile E.; Mount, David R.; La Point, Thomas W.; Burton, G. Allen; Swift, M. C.

    1996-01-01

    Sediments in many Great Lakes harbors and tributary rivers are contaminated. As part of the USEPA's Assessment and Remediation of Contaminated Sediment (ARCS) program, a number of studies were conducted to determine the nature and extent of sediment contamination in Great Lakes Areas of Concern (AOC). This paper describes the composition of benthic invertebrate communities in contaminated sediments and is one in a series of papers describing studies conducted to evaluate sediment toxicity from three AOC's (Buffalo River, NY; Indiana Harbor, IN; Saginaw River, MI), as part of the ARCS Program. Oligochaeta (worms) and Chironomidae (midge) comprised over 90% of the benthic invertebrate numbers in samples collected from depositional areas. Worms and midge consisted of taxa identified as primarily contaminant tolerant organisms. Structural deformities of mouthparts in midge larvae were pronounced in many of the samples. Good concurrence was evident between measures of laboratory toxicity, sediment contaminant concentration, and benthic invertebrate community composition in extremely contaminated samples. However, in moderately contaminated samples, less concordance was observed between the benthos community composition and either laboratory toxicity test results or sediment contaminant concentration. Laboratory sediment toxicity tests may better identify chemical contamination in sediments than many commonly used measures of benthic invertebrate community composition. Benthic measures may also reflect other factors such as habitat alteration. Evaluation of non-contaminant factors are needed to better interpret the response of benthic invertebrates to sediment contamination.

  16. Comparison of sediment profile image data with profiles of oxygen and Eh from sediment cores

    NASA Astrophysics Data System (ADS)

    Diaz, Robert J.; Trefry, John H.

    2006-10-01

    A study of oil and gas development in the Gulf of Mexico provided a unique opportunity to compare data from sediment profile images (SPI) with that of sediment cores collected at locations in the central Gulf of Mexico from 1034 to 1175 m. Variables measured from SPI included sediment grain-size, sediment texture, apparent depth of oxygen penetration (aDOP) into the sediments, and parameters related to biogenic activity (tubes, burrows, feeding pits or mounds, and subsurface feeding voids). Variables measured from the sediment cores included sedimentation rate, dissolved oxygen profiles, and redox potential (Eh). There was a high degree of concordance between the two data sets based on correlation analysis. For example, the correlation between aDOP and maximum penetration of oxygen into the sediment was 0.69. For deep-sea sediment, SPI provides a means by which general geochemical conditions of near surface sediment can be remotely assessed providing a quick method for mapping surficial geochemistry over large areas.

  17. Flocculated sediments can reduce the size of sediment basin at construction sites.

    PubMed

    Kang, Jihoon; King, Scott E; McLaughlin, Richard A

    2016-01-15

    Due to stringent water quality regulations on stormwater discharges, there is increasing interest in chemically-assisted settling of suspended sediments at construction sites. This study investigated settling characteristics of flocculated sediment by polyacrylamide (PAM) in a top-loading settling tube. Studied sediment materials were obtained from construction sites in North Carolina, USA: Coastal Plain loamy sand (CPLS), Piedmont sandy clay loam (PSCL), Piedmont silt loam (PSL), and Mountain clay loam (MCL). The four different sediment suspensions mixed with and without dissolved PAM were introduced to the top of the column individually. During a 1-h settling period, samples were taken at 1-m depth from surface at various times and analyzed for total suspended solids (TSS). Flocculated sediment by PAM greatly increased its settled TSS fraction up to 95-97% only in 1-min settling period compared to those of unflocculated sediment (16-72%). The settling improvement by PAM was profound in the finer-textured soils (PSL and MCL) by increasing their median particle settling velocity (>2 cm s(-1)) compared to unflocculated counterparts (<1.1 cm s(-1)). Estimated surface area requirement of sediment basin suggested that the basins receiving flocculated sediment could be reduced in size (surface area) by 2- to 4-times compared to those receiving unflocculated sediment. Our results suggests that current sediment basin design could be modified when chemically-assisted settling is implemented, taking up less space and cost in construction sites.

  18. A process-based model for aeolian sediment transport and spatiotemporal varying sediment availability

    NASA Astrophysics Data System (ADS)

    Hoonhout, Bas M.; Vries, Sierd de

    2016-08-01

    Aeolian sediment transport is influenced by a variety of bed surface properties, like moisture, shells, vegetation, and nonerodible elements. The bed surface properties influence aeolian sediment transport by changing the sediment transport capacity and/or the sediment availability. The effect of bed surface properties on the transport capacity and sediment availability is typically incorporated through the velocity threshold. This approach appears to be a critical limitation in existing aeolian sediment transport models for simulation of real-world cases with spatiotemporal variations in bed surface properties. This paper presents a new model approach for multifraction aeolian sediment transport in which sediment availability is simulated rather than parameterized through the velocity threshold. The model can cope with arbitrary spatiotemporal configurations of bed surface properties that either limit or enhance the sediment availability or sediment transport capacity. The performance of the model is illustrated using four prototype cases, the simulation of two wind tunnel experiments from literature and a sensitivity analysis of newly introduced parameters.

  19. Microbial interactions with naturally occurring hydrophobic sediments: Influence on sediment and associated contaminant mobility.

    PubMed

    Droppo, I G; Krishnappan, B G; Lawrence, J R

    2016-04-01

    The erosion, transport and fate of sediments and associated contaminants are known to be influenced by both particle characteristics and the flow dynamics imparted onto the sediment. The influential role of bitumen containing hydrophobic sediments and the microbial community on sediment dynamics are however less understood. This study links an experimental evaluation of sediment erosion with measured sediment-associated contaminant concentrations and microbial community analysis to provide an estimate of the potential for sediment to control the erosion, transport and fate of contaminants. Specifically the paper addresses the unique behaviour of hydrophobic sediments and the role that the microbial community associated with hydrophobic sediment may play in the transport of contaminated sediment. Results demonstrate that the hydrophobic cohesive sediment demonstrates unique transport and particle characteristics (poor settling and small floc size). Biofilms were observed to increase with consolidation/biostabilization times and generated a unique microbial consortium relative to the eroded flocs. Natural oil associated with the flocs appeared to be preferentially associated with microbial derived extracellular polymeric substances. While PAHs and naphthenic acid increased with increasing shear (indicative of increasing loads), they tended to decrease with consolidation/biostabilization (CB) time at similar shears suggesting a chemical and/or biological degradation. PAH and napthenic acid degrading microbes decreased with time as well, which may suggest that there was a reduced pool of PAHs and naphthenic acids available resulting in their die off. This study emphasizes the importance that any management strategies and operational assessments for the protection of human and aquatic health incorporate the sediment (suspended and bed sediment) and biological (biofilm) compartments and the energy dynamics within the system in order to better predict contaminant

  20. Numerical Experiments on Sediment Pulse Dynamics

    NASA Astrophysics Data System (ADS)

    Morgan, J. A.; Nelson, P. A.

    2015-12-01

    Local channel morphology is highly dependent on sediment supply from upstream reaches. Sediment pulses are introduced to channels during natural and anthropogenic disturbances such as landslides, dam removal, or gravel augmentation. Flume studies have shown that sediment pulses tend to evolve through some combination of translation and dispersion, but the relative importance of the sediment pulse size, the grain size of the pulse material, flow unsteadiness, and channel nonuniformity is poorly understood. Here we use a one-dimensional morphodynamic model to simulate the evolution of various sediment pulses in a straight, rectangular channel. The model is capable of determining transcritical flows, using the energy equation for subcritical nodes and a reduced momentum equation for supercritical nodes. Bed evolution and grain size sorting are handled with the mixed-grain-size Exner equation for sediment continuity. A stratigraphy submodel allows the vertical grain size distribution created during deposition to provide feedbacks on morphodynamic processes encountered during degradation. We explore how pulse characteristics such as total mass, feed timing, and grain size distribution affect pulse translation and dispersion. We also consider the influence of steady versus unsteady water discharge and the existence of background sediment feed. Finally, we examine the effect of variations in channel width by varying the amplitude and wavelength of downstream sinusoidal width undulations. Preliminary results suggest that smaller sediment pulses experience a greater degree of translation than larger pulses. Width variations, particularly those of larger amplitudes, were found to result in increased pulse dispersion. Our results suggest that morphodynamic models can facilitate understanding of what controls sediment pulse dynamics, and they may improve predictions and the potential effectiveness of river restoration techniques such as dam removal and gravel augmentation.

  1. Hydraulic potential in Lake Michigan bottom sediments

    USGS Publications Warehouse

    Cartwright, K.; Hunt, C.S.; Hughes, G.M.; Brower, R.D.

    1979-01-01

    The magnitude and direction of groundwater flux in the bottom sediments of Lake Michigan were deduced from measurements made during three shipboard cruises between 1973 and 1975. These factors affect the geochemical environment of the sediments and therefore the distribution of trace elements reported to be present. The near-shore, sandy-bottom and fine-grained, soft, deep-lake sediments were investigated; areas of hard till or bedrock were not included in the study. Thirty-three piezometers were placed in near-shore sands in waters 5-15 m deep. The piezometers were placed an average of 3 m into the bottom sediment. Water levels from the piezometers averaged 0.6 cm above the lake level, equivalent to an upward hydraulic gradient of about 0.002 cm/cm. Water samples taken from the piezometers have a distinctly different chemical composition from that of the lake water. The total dissolved mineral content and hardness of the groundwater are about twice those of the lake water. Twenty-two hydraulic gradient measurements were made in the fine-grained soft deep-lake sediments in waters 48-140 m deep by using a differential-pressure transducer dropped into the sediments. These measurements show an upward gradient averaging 0.2 cm/cm. No chemical data were obtained for the groundwater in the deep-lake sediments. The results of this study indicate that the groundwater flux is upward through the bottom sediments into Lake Michigan and that there is a chemical change in the water near the water-sediment contact. ?? 1979.

  2. Trend analyses with river sediment rating curves

    USGS Publications Warehouse

    Warrick, Jonathan A.

    2015-01-01

    Sediment rating curves, which are fitted relationships between river discharge (Q) and suspended-sediment concentration (C), are commonly used to assess patterns and trends in river water quality. In many of these studies it is assumed that rating curves have a power-law form (i.e., C = aQb, where a and b are fitted parameters). Two fundamental questions about the utility of these techniques are assessed in this paper: (i) How well to the parameters, a and b, characterize trends in the data? (ii) Are trends in rating curves diagnostic of changes to river water or sediment discharge? As noted in previous research, the offset parameter, a, is not an independent variable for most rivers, but rather strongly dependent on b and Q. Here it is shown that a is a poor metric for trends in the vertical offset of a rating curve, and a new parameter, â, as determined by the discharge-normalized power function [C = â (Q/QGM)b], where QGM is the geometric mean of the Q values sampled, provides a better characterization of trends. However, these techniques must be applied carefully, because curvature in the relationship between log(Q) and log(C), which exists for many rivers, can produce false trends in â and b. Also, it is shown that trends in â and b are not uniquely diagnostic of river water or sediment supply conditions. For example, an increase in â can be caused by an increase in sediment supply, a decrease in water supply, or a combination of these conditions. Large changes in water and sediment supplies can occur without any change in the parameters, â and b. Thus, trend analyses using sediment rating curves must include additional assessments of the time-dependent rates and trends of river water, sediment concentrations, and sediment discharge.

  3. Denitrification in San Francisco Bay intertidal sediments

    USGS Publications Warehouse

    Oremland, Ronald S.; Umberger, Cindy; Culbertson, Charles W.; Smith, Richard L.

    1984-01-01

    The acetylene block technique was employed to study denitrification in intertidal estuarine sediments. Addition of nitrate to sediment slurries stimulated denitrification. During the dry season, sediment-slurry denitrification rates displayed Michaelis-Menten kinetics, and ambient NO3− + NO2− concentrations (≤26 μM) were below the apparent Km (50 μM) for nitrate. During the rainy season, when ambient NO3− + NO2− concentrations were higher (37 to 89 μM), an accurate estimate of the Km could not be obtained. Endogenous denitrification activity was confined to the upper 3 cm of the sediment column. However, the addition of nitrate to deeper sediments demonstrated immediate N2O production, and potential activity existed at all depths sampled (the deepest was 15 cm). Loss of N2O in the presence of C2H2 was sometimes observed during these short-term sediment incubations. Experiments with sediment slurries and washed cell suspensions of a marine pseudomonad confirmed that this N2O loss was caused by incomplete blockage of N2O reductase by C2H2 at low nitrate concentrations. Areal estimates of denitrification (in the absence of added nitrate) ranged from 0.8 to 1.2 μmol of N2 m−2 h−1 (for undisturbed sediments) to 17 to 280 μmol of N2 m−2 h−1 (for shaken sediment slurries).

  4. Denitrification in San Francisco Bay intertidal sediments

    SciTech Connect

    Oremland, R.S.; Umberger, C.; Culbertson, C.W.; Smith, R.L.

    1984-05-01

    The acetylene block technique was employed to study denitrification in intertidal estuarine sediments. Addition of nitrate to sediment slurries stimulated denitrification. During the dry season, sediment-slurry denitrification rates displayed Michaelis-Menten kinetics, and ambient NO/sub 3//sup -/ + NO/sub 2//sup -/ concentrations (less than or equal to26 ..mu..M) were below the apparent K/sub m/ (50 ..mu..M) for nitrate. During the rainy season, when ambient NO/sub 3//sup -/ + NO/sub 2//sup -/ concentrations were higher (37 to 89 ..mu..M), an accurate estimate of the K/sub m/ could not be obtained. Endogenous denitrification activity was confined to the upper 3 cm of the sediment column. However, the addition of nitrate to deeper sediments demonstrated immediate N/sub 2/O production, and potential activity existed at all depths sampled (the deepest was 15 cm). Loss of N/sub 2/O in the presence of C/sub 2/H/sub 2/ was sometimes observed during these short-term sediment incubations. Experiments with sediment slurries and washed cells suspensions of a marine pseudomonad confirmed that this N/sub 2/O loss was caused by incomplete blockage of N/sub 2/O reductase by C/sub 2/H/sub 2/ at low nitrate concentrations. Areal estimates of denitrification (in the absence of added nitrate) ranged from 0.8 to 1.2 ..mu..mol of N/sub 2/ m/sup -2/ h/sup -1/ (for undisturbed sediments) to 17 to 280 ..mu..mol of N/sub 2/ m/sup -2/ h/sup -1/ (for shaken sediment slurries). 32 references

  5. Sedimentation in mountain streams: A review of methods of measurement

    USGS Publications Warehouse

    Hedrick, Lara B.; Anderson, James T.; Welsh, Stuart; Lin, Lian-Shin

    2013-01-01

    The goal of this review paper is to provide a list of methods and devices used to measure sediment accumulation in wadeable streams dominated by cobble and gravel substrate. Quantitative measures of stream sedimentation are useful to monitor and study anthropogenic impacts on stream biota, and stream sedimentation is measurable with multiple sampling methods. Evaluation of sedimentation can be made by measuring the concentration of suspended sediment, or turbidity, and by determining the amount of deposited sediment, or sedimentation on the streambed. Measurements of deposited sediments are more time consuming and labor intensive than measurements of suspended sediments. Traditional techniques for characterizing sediment composition in streams include core sampling, the shovel method, visual estimation along transects, and sediment traps. This paper provides a comprehensive review of methodology, devices that can be used, and techniques for processing and analyzing samples collected to aid researchers in choosing study design and equipment.

  6. Suspended-sediment inflows to Watts Bar Reservoir. Revision 1

    SciTech Connect

    Ewing, L.K.

    1993-09-01

    Suspended-sediment inflows to Watts Bar Reservoir are important data that are required in numerical modeling of transport and deposition of sediment in the reservoir. Acceptable numerical modeling requires sediment inflow rates and locations in order to be able to compute the location and quantity of sediment deposited within the reservoir. Therefore, the representativeness of modeling results is highly dependent on the characteristics of sediment input to the model. The following recommendations, that account for suspended-sediment inflows to be used in the numerical modeling of sediment transport and deposition in Watts Bar Reservoir, were developed through an evaluation of available watershed and sediment deposition data. (1) Use the suspended-sediment rating regression equations of Gaydos et al., for Emory River at Oakdale, TN, and for Poplar Creek near Oak Ridge, TN, to represent the suspended-sediment inflows into Watts Bar Reservoir from its tributaries; (2) Use a suspended-sediment rating regression equation that was derived from suspended-sediment and streamflow data of the Little Tennessee River at McGhee, TN, to represent sediment inflow from the Little Tennessee River for simulation of any historical year before the completion of Tellico Dam; (3) Check the appropriateness of any assumption for suspended-sediment inflows from upstream reservoirs by using its long-term relationship to local suspended-sediment inflows and to the suspended-sediment outflow through Watts Bar Dam; and (4) Focus refinements to suspended-sediment inflow rates on the Clinch arm of Watts Bar Reservoir.

  7. Notes on sedimentation activities calendar year 1990

    USGS Publications Warehouse

    ,

    1991-01-01

    This report is a digest of information furnished by Federal agencies conducting sedimentation investigations. The decision to publish the report was made in 1946, from a proposal by the Chairman of the Federal Interagency River Basin Committee, Subcommittee on Sedimentation. The subcommittee approved the proposal and agreed to issue this report as a means of effecting better coordination of the work of various Federal agencies in the field of sedimentation. The report was issued on a quarterly basis in 1946 and 1947, from 1948 to 1953 reports were issued every 6 months, and from 1954 to the present, the report has been issued annually.

  8. Notes on sedimentation activities calendar year 1992

    USGS Publications Warehouse

    ,

    1994-01-01

    This report is a digest of information furnished by Federal agencies conducting sedimentation investigations. The decision to publish the report was made in 1946, from a proposal by the Chairman of the Federal Interagency River Basin Committee, Subcommittee on Sedimentation. The subcommittee approved the proposal and agreed to issue this report as a means of effecting better coordination of the work of various Federal agencies in the field of sedimentation. The report was issued on a quarterly basis in 1946 and 1947, from 1948 to 1953 reports were issued every 6 months, and from 1954 to present, the report has been issued annually.

  9. Notes on sedimentation activities calendar year 1991

    USGS Publications Warehouse

    ,

    1992-01-01

    This report is a digest of information furnished by Federal agencies conducting sedimentation investigations. The decision to publish the report was made in 1946, from a proposal by the Chairman of the Federal Interagency River Basin Committee, Subcommittee on Sedimentation. The subcommittee approved the proposal and agreed to issue this report as a means of effecting better coordination of the work of various Federal agencies in the field of sedimentation. The report was issued on a quarterly basis in 1946 and 1947, from 1948 to 1953 reports were issued every 6 months, and from 1954 to the present, the report has been issued annually.

  10. Amyloplast Sedimentation Kinetics in Corn Roots

    NASA Technical Reports Server (NTRS)

    Leopold, A. C.; Sack, F.

    1985-01-01

    Knowledge of the parameters of amyloplast sedimentation is crucial for an evaluation of proposed mechanisms of root graviperception. Early estimates of the rate of root amyloplast sedimentation were as low as 1.2 micron/min which may be too slow for many amyloplasts to reach the vicinity of the new lower wall within the presentation time. On this basis, Haberlandt's classical statolith hypothesis involving amyloplast stimulation of a sensitive surface near the new lower wall was questioned. The aim was to determine the kinetics of amyloplast sedimentation with reference to the presentation time in living and fixed corn rootcap cells as compared with coleoptiles of the same variety.

  11. Modeling Benthic Sediment Processes to Predict Water ...

    EPA Pesticide Factsheets

    The benthic sediment acts as a huge reservoir of particulate and dissolved material (within interstitial water) which can contribute to loading of contaminants and nutrients to the water column. A benthic sediment model is presented in this report to predict spatial and temporal benthic fluxes of nutrients and chemicals in Narragansett Bay. A benthic sediment model is presented in this report to identify benthic flux into the water column in Narragansett Bay. Benthic flux is essential to properly model water quality and ecology in estuarine and coastal systems.

  12. What controls sediment flux in dryland channels?

    NASA Astrophysics Data System (ADS)

    Michaelides, K.; Singer, M. B.

    2010-12-01

    Theories for the development of longitudinal and grain size profiles in perennial fluvial systems are well developed, allowing for generalization of sediment flux and sorting in these fluvial systems over decadal to millennial time scales under different forcings (e.g., sediment supply, climate changes, etc). However, such theoretical frameworks are inadequate for understanding sediment flux in dryland channels subject to spatially and temporally discontinuous streamflow, where transport capacity is usually much lower than sediment supply. In such fluvial systems, channel beds are poorly sorted with weak vertical layering, poorly defined bar forms, minimal downstream fining, and straight longitudinal profiles. Previous work in dryland channels has documented sediment flux at higher rates than their humid counterparts once significant channel flow develops, pulsations in bed material transport under constant discharge, and oscillations in dryland channel width that govern longitudinal patterns in erosion and deposition. These factors point to less well appreciated controls on sediment flux in dryland valley floors that invite further study. This paper investigates the relative roles of hydrology, bed material grain size, and channel width on sediment flux rates in the Rambla de Nogalte in southeastern Spain. Topographic valley cross sections and hillslope and channel particle sizes were collected from an ephemeral-river reach. Longitudinal grain-size variation on the hillslopes and on the channel bed were analysed in order to determine the relationship between hillslope supply characteristics and channel grain-size distribution and longitudinal changes. Local fractional estimates of bed-material transport in the channel were calculated using a range of channel discharge scenarios in order to examine the effect of channel hydrology on sediment transport. Numerical modelling was conducted to investigate runoff connectivity from hillslopes to channel and to examine the

  13. Remediation technologies for oil-contaminated sediments.

    PubMed

    Agarwal, Ashutosh; Liu, Yu

    2015-12-30

    Oil-contaminated sediments pose serious environmental hazards for both aquatic and terrestrial ecosystems. Innovative and environmentally compatible technologies are urgently required to remove oil-contaminated sediments. In this paper, various physical, chemical and biological technologies are investigated for the remediation of oil-contaminated sediments such as flotation and washing, coal agglomeration, thermal desorption, ultrasonic desorption, bioremediation, chemical oxidation and extraction using ionic liquids. The basic principles of these technologies as well as their advantages and disadvantages for practical application have been discussed. A combination of two or more technologies is expected to provide an innovative solution that is economical, eco-friendly and adaptable.

  14. A bioaccumulation bioassay for freshwater sediments

    USGS Publications Warehouse

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

    1990-01-01

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

  15. Sediment storage and yield in an urbanized karst watershed

    NASA Astrophysics Data System (ADS)

    Hart, Evan A.; Schurger, Stephen G.

    2005-08-01

    In karst watersheds, sinkholes and other drainage features control the temporal and spatial pattern of sediment storage across the landscape. However, studies dealing with sedimentation in karst watersheds are scarce and the sediment storage function of sinkholes and caves has not been investigated using a sediment budget approach. In this study, we use estimates of channel erosion, sinkhole sedimentation, and suspended sediment yield to examine changes in sediment storage in the 9 km 2 Upper Pigeon Roost Creek fluviokarst watershed near Cookeville, TN. The study watershed has undergone urbanization over the last ˜ 50 years, and sinkholes and caves in the area show signs of recent sedimentation (buried tree roots, buried cultural artifacts, etc.). While sinkholes are generally considered to be sediment sinks, sinkholes examined in this study are shown to cycle between periods of net sediment storage and net sediment loss. Using copyright dates on trash items buried in sinkhole deposits, we estimated the residence time of sinkhole-stored sediment to range from 6 to 10 years. However, other evidence indicates that some sinkholes may store sediment for several centuries. We propose that sediment storage within sinkholes is controlled by several factors including sinkhole drainage area, sinkhole morphology, and basin sediment yield. In addition, changes in sediment storage in karst watersheds are contingent upon random events such as sinkhole collapses. Annual sediment yield was estimated to be 111 Mg km - 2 year - 1 for the entire study watershed and ranged from 11 to 128 Mg km - 2 year - 1 for 3 sub-watersheds. Sediment eroded from the watershed, perhaps during historic settlement of the area, is stored within a large cave system underlying the city. However, the results of a partial sediment budget indicate that the cave is presently a net sediment source. Overall, the findings indicate that the sediment storage function of caves and sinkholes varies spatially and

  16. CADDIS Volume 2. Sources, Stressors and Responses: Sediments - Detailed Conceptual Diagram

    EPA Pesticide Factsheets

    Introduction to the Sediments module, when to list Sediments as a candidate cause, ways to measure Sediments, simple and detailed conceptual diagrams for Sediments, Sediments module references and literature reviews.

  17. CADDIS Volume 2. Sources, Stressors and Responses: Sediments - Simple Conceptual Diagram

    EPA Pesticide Factsheets

    Introduction to the Sediments module, when to list Sediments as a candidate cause, ways to measure Sediments, simple and detailed conceptual diagrams for Sediments, Sediments module references and literature reviews.

  18. Sediment pollution and dynamic in the Mar Piccolo of Taranto (southern Italy): insights from bottom sediment traps and surficial sediments.

    PubMed

    Bellucci, Luca Giorgio; Cassin, Daniele; Giuliani, Silvia; Botter, Margherita; Zonta, Roberto

    2016-07-01

    Major and trace element, PAH, and PCB concentrations were measured in surface sediments and particles from sediment traps collected in the First and Second Basin of the Mar Piccolo (Gulf of Taranto) in two periods (June-July and August-September, 2013). The aim of the study was to evaluate pollution degree, sediment transport and particle redistribution dynamic within the area. Results confirm the higher contamination of sediments from the First Basin observed by previous researches, particularly for Cu, Hg, Pb, total PAHs, and total PCBs. Advective transport from the First to the Second Basin appears to be the leading transfer mechanism of particles and adsorbed contaminants, as evidenced by measured fluxes and statistical analyses of contaminant concentrations in surficial sediments and particles from sediment traps. Long-range selective transports of PAHs and microbial anaerobic degradation processes for PCBs have been also observed. These results are limited to a restricted time window but are consistent with the presence of transport fluxes at the bottom of the water column. This mechanism deserves further investigation and monitoring activities, potentially being the main responsible of pollutant delivering to the less contaminated sectors of the Mar Piccolo.

  19. Bioavailability of sediment-associated PAHs by Lumbriculus variegatus in sediment cores

    SciTech Connect

    Harkey, G.A. |; VanHoof, P.L.; Landrum, P.F.

    1994-12-31

    Lumbriculus variegatus were exposed four weeks to sediment core sections. Sediment was taken from Lake George in northern Michigan and known to be historically contaminated with PAHs. Bioaccumulation was maximal at the 12--16 cm depth where sediment PAH concentrations were greatest. Accumulation was minimal in surficial and 44--48 cm sections. Accumulation peaked at about 96 h, then declined over the remainder of the study for some of the lower molecular weight PAHs. For most higher molecular weight compounds, accumulation peaked at 2 weeks, then slightly declined at 4 weeks. Uptake rate coefficients stayed relatively constant for specific PAH congeners over the range of sediment depths, suggesting constant bioavailability with sediment aging. Accumulation factors (AFs) of selected congeners were also consistent among sediment depths and were comparable to those calculated for other species reported in previous studies.

  20. Sediment availability on burned hillslopes

    NASA Astrophysics Data System (ADS)

    Nyman, Petter; Sheridan, Gary J.; Moody, John A.; Smith, Hugh G.; Noske, Philip J.; Lane, Patrick N. J.

    2013-12-01

    describes the inherent resistance of soil to erosion. Hillslope erosion models typically consider erodibility to be constant with depth. This may not be the case after wildfire because erodibility is partly determined by the availability of noncohesive soil and ash at the surface. This study quantifies erodibility of burned soils using methods that explicitly capture variations in soil properties with depth. Flume experiments on intact cores from three sites in western United States showed that erodibility of fire-affected soil was highest at the soil surface and declined exponentially within the top 20 mm of the soil profile, with root density and soil depth accounting for 62% of the variation. Variation in erodibility with depth resulted in transient sediment flux during erosion experiments on bounded field plots. Material that contributed to transient flux was conceptualized as a layer of noncohesive material of variable depth (dnc). This depth was related to shear strength measurements and sampled spatially to obtain the probability distribution of noncohesive material as a function of depth below the surface. After wildfire in southeast Australia, the initial dnc ranged from 7.5 to 9.1 mm, which equated to 97-117 Mg ha-1 of noncohesive material. The depth decreased exponentially with time since wildfire to 0.4 mm (or < 5 Mg ha-1) after 3 years of recovery. The results are organized into a framework for modeling fire effects on erodibility as a function of the production and depletion of the noncohesive layer overlying a cohesive layer.

  1. Identification of Regional Sediment Management (RSM) Opportunities Along the Upper Texas Coast Through Sediment Budget Analysis

    DTIC Science & Technology

    2013-03-01

    used to combine these three studies to develop a regional characterization of coastal (including beaches and inlets) sediment transport rates and...Sheridan Willey, Tricia Campbell, Samantha Lambert, Andrew Morang, David King, and Robert Thomas PURPOSE. The purpose of this Coastal and Hydraulics...Engineering Technical Note (CHETN) is to document development of a regional sediment budget and assessment of coastal sediment needs on the Upper Texas

  2. Sediment Analysis Network for Decision Support (SANDS)

    NASA Astrophysics Data System (ADS)

    Hardin, D. M.; Keiser, K.; Graves, S. J.; Conover, H.; Ebersole, S.

    2009-12-01

    Since the year 2000, Eastern Louisiana, coastal Mississippi, Alabama, and the western Florida panhandle have been affected by 28 tropical storms, seven of which were hurricanes. These tropical cyclones have significantly altered normal coastal processes and characteristics in the Gulf region through sediment disturbance. Although tides, seasonality, and agricultural development influence suspended sediment and sediment deposition over periods of time, tropical storm activity has the capability of moving the largest sediment loads in the shortest periods of time for coastal areas. The importance of sediments upon water quality, coastal erosion, habitats and nutrients has made their study and monitoring vital to decision makers in the region. Currently agencies such as United States Army Corps of Engineers (USACE), NASA, and Geological Survey of Alabama (GSA) are employing a variety of in-situ and airborne based measurements to assess and monitor sediment loading and deposition. These methods provide highly accurate information but are limited in geographic range, are not continuous over a region and, in the case of airborne LIDAR are expensive and do not recur on a regular basis. Multi-temporal and multi-spectral satellite imagery that shows tropical-storm-induced suspended sediment and storm-surge sediment deposits can provide decision makers with immediate and long-term information about the impacts of tropical storms and hurricanes. It can also be valuable for those conducting research and for projects related to coastal issues such as recovery, planning, management, and mitigation. The recently awarded Sediment Analysis Network for Decision Support will generate decision support products using NASA satellite observations from MODIS, Landsat and SeaWiFS instruments to support resource management, planning, and decision making activities in the Gulf of Mexico. Specifically, SANDS will generate decision support products that address the impacts of tropical storms

  3. BENTHIC COMMUNITY RESPONSE TO SEDIMENT AMENDMENTS

    EPA Science Inventory

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

  4. Suspended sediment yield mapping of Northern Eurasia

    NASA Astrophysics Data System (ADS)

    Maltsev, K. A.; Yermolaev, O. P.; Mozzherin, V. V.

    2015-03-01

    The mapping of river sediment yields at continental or global scale involves a number of technical difficulties that have largely been ignored. The maps need to show the large zonal peculiarities of river sediment yields, as well as the level (smoothed) local anomalies. This study was carried out to create a map of river sediment yields for Northern Eurasia (within the boundaries of the former Soviet Union, 22 × 106 km2) at a scale of 1:1 500 000. The data for preparing the map were taken from the long-term observations recorded at more than 1000 hydrological stations. The data have mostly been collected during the 20th century by applying a single method. The creation of this map from the study of river sediment yield is a major step towards enhancing international research on understanding the mechanical denudation of land due mainly to erosion.

  5. SEWER AND TANK SEDIMENT FLUSHING: CASE STUDIES

    EPA Science Inventory

    The objective of the report summarized here is to demonstrate that sewer system and storage tank flushing that reduces sediment deposition and accumulation is of prime importance to optimizing performance, maintaining structural integrity, and minimizing pollution of receiving wa...

  6. Isolation of cellulolytic actinomycetes from marine sediments

    SciTech Connect

    Veiga, M.; Esparis, A.; Fabregas, J.

    1983-07-01

    The cellulolytic activity of 36 actinomycetes strains isolated from marine sediments was investigated by the cellulose-azure method. Approximately 50% of the isolates exhibited various degrees of cellulolytic activity. 13 references.

  7. MEASURING CONTAMINANT RESUSPENSION RESULTING FROM SEDIMENT CAPPING

    EPA Science Inventory

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

  8. Quaternary sedimentation in Shelikof Strait, Alaska

    USGS Publications Warehouse

    Hampton, M.A.

    1985-01-01

    Shelikof Strait, a nearly parallel-sided marine channel between the Kodiak island group and the Alaska Penninsula, has experienced a succession of distinct sedimentary environments during Quaternary time. Pleistocene glaciers carved a deep basin into bedrock in the southwest part of the strait and a shallower platform surface with incised channels in the northeast. The basin and channels were filled with glacial and glacialmarine sediment before and during the time that ice retreated and oceanic conditions returned. Restricted marine conditions prevailed in early Holocene time and sediment prograded transversely into the strait from the adjacent landmasses, with some localized dispersal to the deep, central strait. Onset of modern open-marine conditions commenced when regional currents breached the sill across Kennedy and Stevenson Entrances to combine with sediment-laden outflow from Cook Inlet and deposit a blanket of well-stratified sediment throughout the strait. ?? 1985.

  9. Microplastic pollution in deep-sea sediments.

    PubMed

    Van Cauwenberghe, Lisbeth; Vanreusel, Ann; Mees, Jan; Janssen, Colin R

    2013-11-01

    Microplastics are small plastic particles (<1 mm) originating from the degradation of larger plastic debris. These microplastics have been accumulating in the marine environment for decades and have been detected throughout the water column and in sublittoral and beach sediments worldwide. However, up to now, it has never been established whether microplastic presence in sediments is limited to accumulation hot spots such as the continental shelf, or whether they are also present in deep-sea sediments. Here we show, for the first time ever, that microplastics have indeed reached the most remote of marine environments: the deep sea. We found plastic particles sized in the micrometre range in deep-sea sediments collected at four locations representing different deep-sea habitats ranging in depth from 1100 to 5000 m. Our results demonstrate that microplastic pollution has spread throughout the world's seas and oceans, into the remote and largely unknown deep sea.

  10. Sediment-Associated Reactions of Aromatic Amines

    EPA Science Inventory

    Sorption of aromatic amines to sediments and soils can occur by both reversible physical processes and irreversible chemical processes. To elucidate the significance of these sorption pathways, the sorption kinetics of aniline and pyridine were studied in resaturated pond sedimen...

  11. Pattern recognition of laminated sediments methodology

    NASA Astrophysics Data System (ADS)

    Barba-Rojo, Perla Karina; Solorza-Calderón, Selene; González-Fernández, Antonio

    2016-12-01

    This work presents a different aproach for laminae counting and thickness measurements on laminated sediment images. This is done by the use of morphological operations and minimum variance quantization.

  12. Magnesium Isotopic Composition of Subducting Marine Sediments

    NASA Astrophysics Data System (ADS)

    Hu, Y.; Teng, F. Z.; Plank, T. A.; Huang, K. J.

    2015-12-01

    Subducted marine sediments have recently been called upon to explain the heterogeneous Mg isotopic composition (δ26Mg, ‰) found in mantle wehrlites (-0.39 to +0.09 [1]) in the context of a homogeneous mantle (-0.25 ± 0.07 [2]). However, no systematic measurements of δ26Mg on marine sediments are currently available to provide direct support to this model. To characterize the Mg inputs to global subduction zones, we measured δ26Mg data for a total of 90 marine sediments collected from 12 drill sites outboard of the world's major subduction zones. These sediments span a 1.73‰ range in δ26Mg. The detritus-dominated sediments have δ26Mg (-0.59 to +0.53) comparable to those of weathered materials on continents (e.g. -0.52 to +0.92 [3]), while the calcareous oozes yield δ26Mg (as light as -1.20) more similar to the seawater value (-0.83 [4]). The negative correlation between δ26Mg and CaO/Al2O3 in these sediments indicates the primary control of mineralogy over the Mg isotopic distribution among different sediment types, as carbonates are enriched in light Mg isotopes (-5.10 to -0.40 [5]) whereas clay-rich weathering residues generally have heavier δ26Mg (e.g. up to +0.65 in saprolite [6]). In addition, chemical weathering and grain-size sorting drive sediments to a heavier δ26Mg, as indicated by the broad positive trends between δ26Mg with CIA (Chemical Index of Alteration [7]) and Al2O3/SiO2, respectively. Collectively, the arc systems sampled in this study represent ~30% of global arc length and the extrapolated global Mg flux of subducting marine sediments accounts for ~9% of the yearly Mg riverine input with a flux-weighted average δ26Mg at -0.26. Subduction of these heterogeneous sediments may not cause significant mantle heterogeneity on a global scale, but the highly variable Mg fluxes and δ26Mg of sediments delivered to different trenches are capable of producing local mantle variations. Volcanic rocks sourced from these mantle domains are thus

  13. Age Dating Fluvial Sediment Storage Reservoirs to Construct Sediment Waiting Time Distributions

    NASA Astrophysics Data System (ADS)

    Skalak, K.; Pizzuto, J. E.; Benthem, A.; Karwan, D. L.; Mahan, S.

    2015-12-01

    Suspended sediment transport is an important geomorphic process that can often control the transport of nutrients and contaminants. The time a particle spends in storage remains a critical knowledge gap in understanding particle trajectories through landscapes. We dated floodplain deposits in South River, VA, using fallout radionuclides (Pb-210, Cs-137), optically stimulated luminescence (OSL), and radiocarbon dating to determine sediment ages and construct sediment waiting time distributions. We have a total of 14 age dates in two eroding banks. We combine these age dates with a well-constrained history of mercury concentrations on suspended sediment in the river from an industrial release. Ages from fallout radionuclides document sedimentation from the early 1900s to the present, and agree with the history of mercury contamination. OSL dates span approximately 200 to 17,000 years old. We performed a standard Weibull analysis of nonexceedance to construct a waiting time distribution of floodplain sediment for the South River. The mean waiting time for floodplain sediment is 2930 years, while the median is approximately 710 years. When the floodplain waiting time distribution is combined with the waiting time distribution for in-channel sediment storage (available from previous studies), the mean waiting time shifts to approximately 680 years, suggesting that quantifying sediment waiting times for both channel and floodplain storage is critical in advancing knowledge of particle trajectories through watersheds.

  14. Assessing upper Mississippi River sediments using benthic invertebrates and the sediment quality triad

    SciTech Connect

    Canfield, T.J.; Brunson, E.L.; Dwyer, F.J.; Ingersoll, C.G.; Kemble, N.E.

    1995-12-31

    Benthic invertebrate samples were collected from 23 pools in the Upper Mississippi River (UMR) and from one station in the Saint Croix River (SCR) as part of study to assess the effects of the extensive flooding of 1993 on sediment contamination in the UMR system. Sediment contamination consists of organic and inorganic contaminants. Samples were collected with a petite ponar grab sampler Oligochaete and Chironomid abundance constituted over 80% of the community in samples from 18 of 23 pools in the UMR and in the SCR sample. Fingernail clams comprised a large portion of the community in 5 of 23 UMR pools. Total abundance values ranged from 333/m{sup 2} at pool 1 to 25,000/m{sup 2} at pool 19. Overall frequency of chironomid mouth part deformities was 3%, which is comparable to literature values for incidence of deformities in uncontaminated sediments. Occurrence of mouth part deformities ranged 0 to 13% at the UMR pools. Sediment contamination was generally low in the UMR pools and the SCR site. The degree of sediment contamination will be evaluated with data from laboratory toxicity exposures, sediment chemistry analyses and benthic community analyses using the Sediment Quality Triad approach. Preliminary evaluations show the sediments from the UMR and SCR are relatively uncontaminated and the flooding of `93 did not adversely effect sediment quality in the UMR system.

  15. Sediment contact tests as a tool for the assessment of sediment quality in German waters.

    PubMed

    Feiler, Ute; Höss, Sebastian; Ahlf, Wolfgang; Gilberg, Daniel; Hammers-Wirtz, Monika; Hollert, Henner; Meller, Michael; Neumann-Hensel, Helga; Ottermanns, Richard; Seiler, Thomas-Benjamin; Spira, Denise; Heininger, Peter

    2013-01-01

    A sediment contact test (SCT) battery consisting of five ecotoxicological test systems was applied to 21 native freshwater sediments characterized by a broad variety of geochemical properties and anthropogenic contamination. Higher plants (Myriophyllum aquaticum), nematodes (Caenorhabditis elegans), oligochaetes (Lumbriculus variegatus), zebrafish embryos (Danio rerio), and bacteria (Arthrobacter globiformis), representing various trophic levels and exposure pathways, were used as test organisms. The test battery detected sediment toxicity caused by anthropogenic pollution, whereas the various tests provided site-specific, nonredundant information to the overall toxicity assessment. Based on the toxicity pattern derived from the test battery, the sediments were classified according to a newly proposed classification system for sediment toxicity assessment. The SCT-derived classification generally agreed well with the application of consensus-based sediment quality guidelines (SQGs), especially with regard to sediments with high toxic potential. For sediments with low to medium toxic potential, the SQGs often underestimated the toxicity that was detected by the SCTs, underpinning the need for toxicity tests in sediment quality assessment.

  16. Self-sedimentation of fossil phytoplankton blooms, laminated hemipelagic sediments and the oceanic carbon cycle

    SciTech Connect

    Grimm, K.A.; Lange, C.B.

    1996-12-31

    The flux of phytoplankton-derived organic carbon from the surface ocean to the deep sea and underlying sediments is a nonuniform process that significantly impacts biogeochemical cycles, atmospheric pCO{sub 2} / O{sub 2} and organic carbon enrichment in marine sediments. Some marine phytoplankton actively drive the sedimentation process by the formation of sticky transparent gels which facilitate aggregation, rapid sinking and efficient export flux. Here we present fossil evidence of unfragmented, low-diversity phytoplankton assemblages preserved as sedimentary laminations and as preserved aggregates that are attributable to a similar phytoplankton-driven sedimentary mechanism, here termed {open_quotes}self-sedimentation{close_quotes}. Heterogeneities in the texture and/or composition of sediment supply are necessary for the production of laminatedhemipelagic sediments; the absence of hydraulic and biological reworking permits preservation of these sedimentary laminae. Distinctly-laminated core intervals are characterized by large compositional contrasts between adjacent laminae; many such high-bimodality couplets are attributable to self-sedimentation of phytoplankton blooms. Self-sedimentation propels the formation of some conspicuous hemipelagic sedimentary laminations and results in efficient carbon and opal flux to the sediments. These records suggest that phytoplankton-mediated changes in the efficiency of the biological carbon pump may govern many accumulations of organic-rich hydrocarbon source rock as well as many abrupt changes in atmospheric pCO{sub 2} and climate.

  17. Self-sedimentation of fossil phytoplankton blooms, laminated hemipelagic sediments and the oceanic carbon cycle

    SciTech Connect

    Grimm, K.A. ); Lange, C.B. )

    1996-01-01

    The flux of phytoplankton-derived organic carbon from the surface ocean to the deep sea and underlying sediments is a nonuniform process that significantly impacts biogeochemical cycles, atmospheric pCO[sub 2] / O[sub 2] and organic carbon enrichment in marine sediments. Some marine phytoplankton actively drive the sedimentation process by the formation of sticky transparent gels which facilitate aggregation, rapid sinking and efficient export flux. Here we present fossil evidence of unfragmented, low-diversity phytoplankton assemblages preserved as sedimentary laminations and as preserved aggregates that are attributable to a similar phytoplankton-driven sedimentary mechanism, here termed [open quotes]self-sedimentation[close quotes]. Heterogeneities in the texture and/or composition of sediment supply are necessary for the production of laminatedhemipelagic sediments; the absence of hydraulic and biological reworking permits preservation of these sedimentary laminae. Distinctly-laminated core intervals are characterized by large compositional contrasts between adjacent laminae; many such high-bimodality couplets are attributable to self-sedimentation of phytoplankton blooms. Self-sedimentation propels the formation of some conspicuous hemipelagic sedimentary laminations and results in efficient carbon and opal flux to the sediments. These records suggest that phytoplankton-mediated changes in the efficiency of the biological carbon pump may govern many accumulations of organic-rich hydrocarbon source rock as well as many abrupt changes in atmospheric pCO[sub 2] and climate.

  18. Alkaline Phosphatase Assay for Freshwater Sediments: Application to Perturbed Sediment Systems

    PubMed Central

    Sayler, Gary S.; Puziss, Marla; Silver, Martin

    1979-01-01

    The p-nitrophenyl phosphate hydrolysis-phosphatase assay was modified for use in freshwater sediment. Laboratory studies indicated that the recovery of purified alkaline phosphatase activity was 100% efficient in sterile freshwater sediments when optimized incubation and sonication conditions were used. Field studies of diverse freshwater sediments demonstrated the potential use of this assay for determining stream perturbation. Significant correlations between phosphatase and total viable cell counts, as well as adenosine triphosphate biomass, suggested that alkaline phosphatase activity has utility as an indicator of microbial population density and biomass in freshwater sediments. PMID:16345464

  19. Determining annual suspended sediment and sediment-associated trace element and nutrient fluxes

    USGS Publications Warehouse

    Horowitz, A.J.

    2008-01-01

    Suspended sediment is a major factor in the biological and geochemical cycling of trace elements and nutrients in aquatic systems. The design of effective studies involving the collection, processing, and subsequent chemical analysis of suspended sediment requires a clear understanding of the problems associated with using this sample medium. This review summarizes the current state of knowledge relative to the various issues/problems associated with the collection of representative suspended sediment samples in fluvial systems. It also addresses issues associated with accurately determining the concentrations and fluxes of sediment-associated trace elements and nutrients.

  20. A Manual to Identify Sources of Fluvial Sediment

    EPA Science Inventory

    Sedimentation is one of the main causes of stream/river aquatic life use impairments in R3. Currently states lack standard guidance on appropriate tools available to quantify sediment sources and develop sediment budgets in TMDL Development. Methods for distinguishing sediment t...

  1. A SEDIMENT TOXICITY METHOD USING LEMNA MINOR, DUCKWEED

    EPA Science Inventory

    We developed a Lemna minor sediment toxicity test method to assess sediment contaminants which may affect plants. This 96-hour test used 15 ml of sediment and 2 ml of overlying water which was renewed after 48 hours. Sand was used as the control sediment and also to dilute test ...

  2. Effective particle sizes of cohesive sediment in north Mississippi streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Knowledge of the size of cohesive sediment particles transported in streams is important information for predicting how the sediment and contaminants the sediment may be carrying will be transported by the flow. Cohesive sediments (less than 0.062 mm in diameter) generally are not transported in th...

  3. Inversion of elastic impedance for unconsolidated sediments

    USGS Publications Warehouse

    Lee, Myung W.

    2006-01-01

    Elastic properties of gas-hydrate-bearing sediments are important for quantifying gas hydrate amounts as well as discriminating the gas hydrate effect on velocity from free gas or pore pressure. This paper presents an elastic inversion method for estimating elastic properties of gas-hydrate-bearing sediments from angle stacks using sequential inversion of P-wave impedance from the zero-offset stack and S-wave impedance from the far-offset stack without assuming velocity ratio.

  4. Sulfide and methane production in sewer sediments.

    PubMed

    Liu, Yiwen; Ni, Bing-Jie; Ganigué, Ramon; Werner, Ursula; Sharma, Keshab R; Yuan, Zhiguo

    2015-03-01

    Recent studies have demonstrated significant sulfide and methane production by sewer biofilms, particularly in rising mains. Sewer sediments in gravity sewers are also biologically active; however, their contribution to biological transformations in sewers is poorly understood at present. In this study, sediments collected from a gravity sewer were cultivated in a laboratory reactor fed with real wastewater for more than one year to obtain intact sediments. Batch test results show significant sulfide production with an average rate of 9.20 ± 0.39 g S/m(2)·d from the sediments, which is significantly higher than the areal rate of sewer biofilms. In contrast, the average methane production rate is 1.56 ± 0.14 g CH4/m(2)·d at 20 °C, which is comparable to the areal rate of sewer biofilms. These results clearly show that the contributions of sewer sediments to sulfide and methane production cannot be ignored when evaluating sewer emissions. Microsensor and pore water measurements of sulfide, sulfate and methane in the sediments, microbial profiling along the depth of the sediments and mathematical modelling reveal that sulfide production takes place near the sediment surface due to the limited penetration of sulfate. In comparison, methane production occurs in a much deeper zone below the surface likely due to the better penetration of soluble organic carbon. Modelling results illustrate the dependency of sulfide and methane productions on the bulk sulfate and soluble organic carbon concentrations can be well described with half-order kinetics.

  5. Sediment transport in two mediterranean regulated rivers.

    PubMed

    Lobera, G; Batalla, R J; Vericat, D; López-Tarazón, J A; Tena, A

    2016-01-01

    Mediterranean climate is characterized by highly irregular rainfall patterns with marked differences between wet and dry seasons which lead to highly variable hydrological fluvial regimes. As a result, and in order to ensure water availability and reduce its temporal variability, a high number of large dams were built during the 20th century (more than 3500 located in Mediterranean rivers). Dams modify the flow regime but also interrupt the continuity of sediment transfer along the river network, thereby changing its functioning as an ecosystem. Within this context, the present paper aims to assess the suspended sediment loads and dynamics of two climatically contrasting Mediterranean regulated rivers (i.e. the Ésera and Siurana) during a 2-yr period. Key findings indicate that floods were responsible for 92% of the total suspended sediment load in the River Siurana, while this percentage falls to 70% for the Ésera, indicating the importance of baseflows on sediment transport in this river. This fact is related to the high sediment availability, with the Ésera acting as a non-supply-limited catchment due to the high productivity of the sources (i.e. badlands). In contrast, the Siurana can be considered a supply-limited system due to its low geomorphic activity and reduced sediment availability, with suspended sediment concentration remaining low even for high magnitude flood events. Reservoirs in both rivers reduce sediment load up to 90%, although total runoff is only reduced in the case of the River Ésera. A remarkable fact is the change of the hydrological character of the River Ésera downstream for the dam, shifting from a humid mountainous river regime to a quasi-invariable pattern, whereas the Siurana experiences the opposite effect, changing from a flashy Mediterranean river to a more constant flow regime below the dam.

  6. Classification of lake sediments using a hydrocyclone.

    PubMed

    Park, J H; Jo, Y M; Oh, J M

    2003-01-01

    The present work is a preliminary experiment for hydrocyclones as a primary process in lake sediment thickening. A few cyclones based on the Rietema standard geometry were prepared, and sample particles were sediments from a local lake and waste coal fly ash for a reference test. As a result of the chemical analysis, more organic contaminants were found in smaller particles. The experimental tests showed that physical characteristics of particles, configuration of the cyclone and operation conditions could affect the separation efficiency.

  7. Sediment transport monitoring for sustainable hydropower development

    NASA Astrophysics Data System (ADS)

    Rüther, Nils; Guerrero, Massimo; Stokseth, Siri

    2015-04-01

    Due to the increasing demand of CO2 neutral energy not only in Europe but also in World, a relatively large amount of new hydro power plants (HPP) are built. In addition, will existing ones refurbished and renewed in order to run them more cost effective. A huge thread to HPPs is incoming sediments in suspension from the rivers upstream. The sediments settle in the reservoir and reduce the effective head and volume and reduce consequently the life time of the reservoir. In addition are the fine sediments causing severe damages to turbines and infrastructure of a HPP. For estimating the amount of incoming sediments in suspension and therefore planning efficient counter measures, it is essential to monitor the rivers within the catchment of the HPP for suspended sediments. This work is considerably time consuming and requires highly educated personnel and is therefore expensive. Consequently will this study present a method to measure suspended sediment concentrations and their grain size distribution with a dual frequency acoustic Doppler current profiler (ADCP). This method is more cost effective and reliable in comparison to traditional measurement methods. Having more detailed information about the sediments being transported in a river, the hydro power plant can be planned, built, and operated much more efficiently and sustainable. The two horizontal ADCPs are installed at a measurement cross section in the Devoll river in Albania. To verify the new method, the suspended load concentrations will be monitored also in the traditional ways at the same cross sections. It is planned to install turbidity measurement devices included with an automatic sampling devices. It is also planned to use an optical in situ measurement device (LISST SL by Sequoia Inc.) to have detailed information of sediment concentration and grain sizes over the depth.

  8. Interaction of fine sediment with alluvial streambeds

    USGS Publications Warehouse

    Jobson, H.E.; Carey, W.P.

    1989-01-01

    An alluvial streambed can have a large capacity to store fine sediments that are extracted from the flow when instream concentrations are high and it can gradually release fine sediment to the flow when the instream concentrations are low. Several types of storage mechanisms are available depending on the relative size distribution of the suspended load and bed material, as well as the flow hydraulics. -from Authors

  9. Oceanic sediment volumes and continental drift.

    PubMed

    Gilluly, J

    1969-11-21

    The volume of sediment off the Atlantic Coast of the United States is at least six times as great as that off the Pacific Coast. This disparity is readily accounted for if the continent is drifting westward and has overrun large volumes of sediment on a former Benioff zone. Such an overrunning is also consonant with many features of the geology of the western United States.

  10. NUMERICAL MODELING OF FINE SEDIMENT PHYSICAL PROCESSES.

    USGS Publications Warehouse

    Schoellhamer, David H.

    1985-01-01

    Fine sediment in channels, rivers, estuaries, and coastal waters undergo several physical processes including flocculation, floc disruption, deposition, bed consolidation, and resuspension. This paper presents a conceptual model and reviews mathematical models of these physical processes. Several general fine sediment models that simulate some of these processes are reviewed. These general models do not directly simulate flocculation and floc disruption, but the conceptual model and existing functions are shown to adequately model these two processes for one set of laboratory data.

  11. Descriptions of WHOI Sediment Cores, Volume 8

    DTIC Science & Technology

    1993-05-01

    Siliceous Detrital grains Foraminifera Diatoms Micronodules Nannofossils Radiolaria Zeolites Discoasters Sponges Volcanic shards Pteropods...excess of 15%. 1 15% < % inorganic components < 30% detrital grains Mn micronodules (MAJOR SEDIMENT NAME) with zeolites volcanic ash -- etc. % inorganic...components > 30% detrital grains Mn micronodules (MAJOR SEDIMENT NAME) / zeolites volcanic ash -- etc. I 1 , u~ ;U L)I 0.1 CC - 12 P*- 4-)U UU 0 rm UU

  12. Evaluating Sediment Mobility for Siting Nearshore Berms

    DTIC Science & Technology

    2016-04-01

    Engineering Technical Note (CHETN) describes two methods to quickly assess sediment mobility relative to water depth as a function of local waves and...currents. Estimating dredged sediment mobility relative to placement depth and grain size is valuable for preliminary or reconnaissance engineering...Reynold’s number, Rw , relative roughness, r, and the semi-orbital excursion, A, which are given as ww U A R ν  (8) s Ar k  (9) and wU

  13. Dispersion of Sound in Marine Sediments

    DTIC Science & Technology

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Dispersion of Sound in Marine Sediments N. Ross...our understanding of the interaction of sound with the ocean bottom is the frequency dependence of sound speed and attenuation in marine sediments...The long term goals of this research project are related to the investigation of dispersion of sound speed and attenuation at low frequencies (< 2

  14. Gas Bubble Growth In Muddy Sediments

    DTIC Science & Technology

    2002-09-30

    1 Gas Bubble Growth In Muddy Sediments Bruce D . Johnson Department of Oceanography, Dalhousie University Halifax, Nova Scotia, Canada B3H 4J1 phone...that this information can be used to improve and test acoustic backscatter models for sediments and to better understand the ebullitive flux of...currently valid OMB control number. 1. REPORT DATE 30 SEP 2002 2. REPORT TYPE 3. DATES COVERED 00-00-2002 to 00-00-2002 4. TITLE AND SUBTITLE

  15. Gas Bubble Growth in Muddy Sediments

    DTIC Science & Technology

    2001-09-30

    1 Gas Bubble Growth In Muddy Sediments Bruce D . Johnson Department of Oceanography, Dalhousie University Halifax, Nova Scotia, Canada B3H 4J1 phone...that this information can be used to improve and test acoustic backscatter models for sediments and to better understand the ebullitive flux of...currently valid OMB control number. 1. REPORT DATE 30 SEP 2001 2. REPORT TYPE 3. DATES COVERED 00-00-2001 to 00-00-2001 4. TITLE AND SUBTITLE

  16. Dispersion of plutonium from contaminated pond sediments

    USGS Publications Warehouse

    Rees, T.F.; Cleveland, J.M.; Carl, Gottschall W.

    1978-01-01

    Sediment-water distributions of plutonium as a function of pH and contact time are investigated in a holding pond at the Rocky Flats plant of the Department of Energy. Although plutonium has been shown to sorb from natural waters onto sediments, the results of this study indicate that under the proper conditions it can be redispersed at pH 9 and above. Concentrations greater than 900 pCi Pu/L result after 34 h contact at pH 11 or 12 and the distribution coefficient, defined as the ratio of concentration in the sediment to that in the liquid, decreases from 1.1 ?? 105 at pH 7 to 1.2 ?? 103 at pH 11. The plutonium is probably dispersed as discrete colloids or as hydrolytic species adsorbed onto colloidal sediment particles whose average size decreases with increasing pH above pH 9. About 5% of the total plutonium is dispersed at pH 12, and the dispersion seems to readsorb on the sediment with time. Consequently, migration of plutonium from the pond should be slow, and it would be difficult to remove this element completely from pond sediment by leaching with high pH solutions. ?? 1978 American Chemical Society.

  17. The Geological Survey sediment program in California

    USGS Publications Warehouse

    Brown, E.

    1957-01-01

    The activities of the Water Resources Division of the U.S. Geological Survey in the State of California arise from the responsibility place on this agency by Congress for the determination and appraisal of the nation's water resources. The stream-sediment programs of the division are designed to carry out this broad responsibility and include systematic measurement of the sediment load carried by streams, studies of course and movement of fluvial sediment, and research on the mechanics of fluvial-sediment movement. In order to effectively consummate these programs over the Nation, finds are appropriated by Congress and earmarked in part from what is termed the federal program and in part for the cooperative program to match on a 50-50 basis, offerings at the State or local level. The federal stream-sediment program is comprised of investigations in which the federal steam-sediment program is comprised of investigations in which the federal or national interest is predominant and, accordingly, the costs are borne entirely by the federal government. It is expected that come all-federal finds will be allocated in fiscal year 1958 to projects in California, but the amount us not as yet known.

  18. Hydraulics characteristics of tipping sediment flushing gate.

    PubMed

    Bong, C H J; Lau, T L; Ab Ghani, A

    2013-01-01

    This paper highlights a preliminary study on the potential of a tipping flush gate to be used in an open storm drain to remove sediment. The investigation was carried out by using a plasboard model of the tipping flush gate installed in a rectangular flume. A steady flow experiment was carried out to determine the discharge coefficients and also the outflow relationship of the tipping flush gate. The velocity produced by the gate at various distances downstream of the gate during flushing operation was measured using a flowmeter and the velocity at all the points was higher than the recommended self-cleansing design available in the literature. A preliminary experiment on the efficiency of flushing was conducted using uniform sediment with d50 sizes of 0.81, 1.53 and 4.78 mm. Results generally showed that the number of flushes required to totally remove the sediment from the initial position by a distance of 1 m increased by an average of 1.50 times as the sediment deposit bed thickness doubled. An equation relating the number of flushes required to totally remove the sediment bed for 1 m with the sediment bed deposit thickness was also developed for the current study.

  19. Linking nutrient enrichment, sediment erodibility and biofilms

    NASA Astrophysics Data System (ADS)

    Conrad, B.; Mahon, R.; Sojka, S. L.

    2014-12-01

    Sediment movement in coastal lagoons affects nutrient flux and primary producer growth. Previous research has shown that sediment erodibility is affected by biofilm concentration and that growth of benthic organisms, which produce biofilm, is affected by nutrient enrichment. However, researchers have not examined possible links between nutrient addition and sediment erodibility. We manipulated nutrient levels in the water column of 16 microcosms filled with homogenized sediment from a shallow coastal lagoon and artificial seawater to determine the effects on biofilm growth, measured through chlorophyll a and colloidal carbohydrate concentrations. Erosion tests using a Gust microcosm were conducted to determine the relationship between sediment erodibility and biofilm concentration. Results show that carbohydrate levels decreased with increasing nutrient enrichment and were unrelated to chlorophyll concentrations and erodibility. The nutrient levels did not predictably affect the chlorophyll levels, with lower chlorophyll concentrations in the control and medium enrichment treatments than the low and high enrichment treatments. Controls on biofilm growth are still unclear and the assumed relationship between carbohydrates and erodibility may be invalid. Understanding how biofilms respond to nutrient enrichment and subsequent effects on sediment erodibility is essential for protecting and restoring shallow coastal systems.

  20. Sedimentation counting and morphology of Mycoplasma.

    PubMed

    Clark, H W

    1965-11-01

    Clark, Harold W. (The George Washington University School of Medicine, Washington, D.C.). Sedimentation counting and morphology of Mycoplasma. J. Bacteriol. 90:1373-1386. 1965.-The sedimentation technique for counting viral particles was applied to the quantitation and morphological identification of Mycoplasma in broth cultures. Mycoplasma, apparently in their native form, firmly adhered to the surface, when sedimented on glass cover slips or onto electron microscope grids. The sedimented cover slip preparations stained with crystal violet could be readily counted in the light microscope. The cultures sedimented onto electron microscope grids were readily counted at low magnification and provided excellent preparations for morphological examination at higher magnifications. It was found that air-dried Mycoplasma particles were enlarged considerably because of excessive flattening. Fixation of sedimented Mycoplasma particles in diluted OsO(4) prior to air drying yielded a more realistic morphology, with various sizes and shapes in the stages of the growth cycle exhibited. A new technique of differentially staining Mycoplasma colonies on agar plates was developed to facilitate the quantitation of viable colony-forming units for comparison with total counts. The use of plastic or Parafilm gaskets for dry mounting was developed to facilitate the handling and examination of the stained cover slip preparations. The results of this investigation indicated that the growth cycle of some Mycoplasma species includes a stage of hexadic fission with the cleavage of minimal reproductive units (less than 100 mmu) containing a limited deoxyribonucleic acid genetic coding molecule (approximately 4 x 10(6)).

  1. Nitrogen Metabolism Genes from Temperate Marine Sediments.

    PubMed

    Reyes, Carolina; Schneider, Dominik; Lipka, Marko; Thürmer, Andrea; Böttcher, Michael E; Friedrich, Michael W

    2017-03-10

    In this study, we analysed metagenomes along with biogeochemical profiles from Skagerrak (SK) and Bothnian Bay (BB) sediments, to trace the prevailing nitrogen pathways. NO3(-) was present in the top 5 cm below the sediment-water interface at both sites. NH4(+) increased with depth below 5 cm where it overlapped with the NO3(-) zone. Steady-state modelling of NO3(-) and NH4(+) porewater profiles indicates zones of net nitrogen species transformations. Bacterial protease and hydratase genes appeared to make up the bulk of total ammonification genes. Genes involved in ammonia oxidation (amo, hao), denitrification (nir, nor), dissimilatory NO3(-) reduction to NH4(+) (nfr and otr) and in both of the latter two pathways (nar, nap) were also present. Results show ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) are similarly abundant in both sediments. Also, denitrification genes appeared more abundant than DNRA genes. 16S rRNA gene analysis showed that the relative abundance of the nitrifying group Nitrosopumilales and other groups involved in nitrification and denitrification (Nitrobacter, Nitrosomonas, Nitrospira, Nitrosococcus and Nitrosomonas) appeared less abundant in SK sediments compared to BB sediments. Beggiatoa and Thiothrix 16S rRNA genes were also present, suggesting chemolithoautotrophic NO3(-) reduction to NO2(-) or NH4(+) as a possible pathway. Our results show the metabolic potential for ammonification, nitrification, DNRA and denitrification activities in North Sea and Baltic Sea sediments.

  2. Discharge of sediment in channelized alluvial streams

    USGS Publications Warehouse

    Simon, Andrew

    1989-01-01

    Approximately 400 million cubic feet of channel sediments have been delivered to the Mississippi River from the Obion-Forked Deer River system in the last 20 years. The discharge of sediment from these channelized networks in West Tennessee varies systematically with the stage of channel evolution. Maximum bed-material discharges occur during the initial phases of degradation (Stage III). In contrast, yields of suspended-sediment peak during the threshold stage (Stage IV: large-scale mass wasting) as sediments are delivered from main-channel banks and tributary beds. Suspended-sediment yields then decrease as aggradation (Stage V) becomes the dominant trend in the main channels, but remains relatively high through restabilization (Stage VI) because of continued degradation and widening in the tributaries. Bed-material discharges decrease from the degradation stage (III) to Stage V, and increase again during restabilization (Stage VI) because secondary aggradation increases gradients and incipient meandering serves to rework bed sediments. Additional aspects of the subject are discussed.

  3. Cokriging estimation of daily suspended sediment loads

    USGS Publications Warehouse

    Li, Z.; Zhang, Y.-K.; Schilling, K.; Skopec, M.

    2006-01-01

    Daily suspended sediment loads (S) were estimated using cokriging (CK) of S with daily river discharge based on weekly, biweekly, or monthly sampled sediment data. They were also estimated with ordinary kriging (OK) and a rating curve method. The estimated daily loads were compared with the daily measured values over a nine-year-period. The results show that the estimated daily sediment loads with the CK using the weekly measured data best matched the measured daily values. The rating curve method based on the same data provides a fairly good match but it tends to underestimate the peak and overestimate the low values. The CK estimation was better than the rating curve because CK considers the temporal correlation among the data values and honors the measured points whereas the rating curve method does not. For the site studied, weekly sampling may be frequent enough for estimating daily sediment loads with CK when daily discharge data is available. The estimated daily loads with CK were less reliable when the sediment samples were taken less frequently, i.e., biweekly or monthly. The OK estimates using the weekly measured data significantly underestimates the daily S because unlike CK and the rating curve, OK makes no use of the correlation of sediment loads with frequently measured river discharge. ?? 2005 Elsevier B.V. All rights reserved.

  4. Sedimentation of athermal particles in clay suspensions

    NASA Astrophysics Data System (ADS)

    Clotet, Xavier; Kudrolli, Arshad

    2015-03-01

    We discuss sedimentation of athermal particles in dense clay suspensions which appear liquid-like to glass-like. These studies are motivated by the physics important to a diverse range of problems including remediation of oil sands after the extraction of hydrocarbons, and formation of filter cakes in bore wells. We approach this problem by first considering collective sedimentation of athermal spherical particles in a viscous liquid in quasi-two dimensional and three dimensional containers. We examine the system using optical and x-ray tomography techniques which gives particle level information besides global information on the evolution of the volume fraction. Unlike sediments in the dilute limit - which can be modeled as isolated particles that sediment with a constant velocity and slow down exponentially as they approach the bottom of the container - we find interaction between the particles through the viscous fluids leads to qualitatively differences. We find significant avalanching behavior and cooperative motion as the grains collectively settle, and non-exponential increase in settling time. We discuss the effect of stirring caused by the sedimenting particles on their viscosity and consequently the sedimentation rates as a function of particle concentration. Supported by Petroleum Research Fund Grant PRF # 54045-ND9.

  5. Hypertrophic lagoon management by sediment disturbance.

    PubMed

    Lenzi, Mauro; Birardi, Francesca; Calzolai, Roberto; Finoia, Maria Grazia; Marcone, Francesco; Nocciolini, Stefano; Roffilli, Rugiada; Sgroi, Sergio; Solari, Duccio

    2010-01-01

    Experimental control of eutrophication in a small coastal lagoon was attempted by means of sediment disturbance. A specially designed boat was used to resuspend the top 3 cm of sediment by a jets of air-water directed towards the bottom. This disturbance was carried out for 3 months in each of two areas with a surface area of 24 and 20 hectares respectively. In a total of 80 stations in these two areas and in two undisturbed areas of 16 and 20 ha, organic matter, porosity, density and redox potential were monitored in sediment bimonthly and free sulphides were monitored in water close to the bottom. Before, during and after disturbance, the impact of daily sediment resuspension on the water column was monitored monthly, as ammonium nitrogen (N-NH4), soluble reactive phosphorus (SRP), dissolved oxygen (DO) and pH. In the whole lagoon, sediment texture was determined at the start and at the end of the experiment in 120 stations, and seaweed (mainly Chaetomorpha linum and Lophosiphonia subadunca) and seagrass (Ruppia cirrhosa) biomasses were estimated in 42 stations every month. The results showed a stable organic matter content in disturbed areas and an increase in undisturbed areas, as well as an increase in seaweed in areas distant from disturbed areas. No significant effect of sediment resuspension on water column N-NH4, SRP, DO or pH was found.

  6. Water-level fluctuations influence sediment porewater ...

    EPA Pesticide Factsheets

    Reservoirs typically have elevated fish mercury (Hg) levels compared to natural lakes and rivers. A unique feature of reservoirs is water-level management which can result in sediment exposure to the air. The objective of this study is to identify how reservoir water-level fluctuations impact Hg cycling, particularly the formation of the more toxic and bioaccumulative methylmercury (MeHg). Total-Hg (THg), MeHg, stable isotope methylation rates and several ancillary parameters were measured in reservoir sediments (including some in porewater and overlying water) that are seasonally and permanently inundated. The results showed that sediment and porewater MeHg concentrations were over 3-times higher in areas experiencing water-level fluctuations compared to permanently inundated sediments. Analysis of the data suggest that the enhanced breakdown of organic matter in sediments experiencing water-level fluctuations has a two-fold effect on stimulating Hg methylation: 1) it increases the partitioning of inorganic Hg from the solid phase into the porewater phase (lower log Kd values) where it is more bioavailable for methylation; and 2) it increases dissolved organic carbon (DOC) in the porewater which can stimulate the microbial community that can methylate Hg. Sulfate concentrations and cycling were enhanced in the seasonally inundated sediments and may have also contributed to increased MeHg production. Overall, our results suggest that reservoir management a

  7. Sediment transport in the nearshore area of Phoenix Island

    NASA Astrophysics Data System (ADS)

    Hu, Rijun; Ma, Fang; Wu, Jianzheng; Zhang, Wei; Jiang, Shenghui; Xu, Yongchen; Zhu, Longhai; Wang, Nan; Liu, Aijiang

    2016-10-01

    Based on the measured data, suspended sediment concentration, surface sediment grain size, current and waves, the sediment transport mechanisms and pathways in the Phoenix Island area were analyzed using methods of flux decomposition and Grain Size Trend Analysis (GSTA). The results show that net suspended sediment is mainly transported by average current, Stokes drift, and gravitational circulation. The transport direction of suspended sediment is varying and basically following the direction of residual tidal currents. Surface sediment transport pathways are primarily parallel to the coastline along with two convergent centers. Waves and longshore currents have a significant influence on sediment transport, but the influence is limited due to a steep and deep underwater bank. Tidal current is the main controlling factor for sediment transport, especially in the deep water area. Neither suspended nor surface sediment is transported towards the southwest. The South Shandong Coastal Current (SSCC) has little effect on sediment transport processes in the nearshore area of Phoenix Island.

  8. Bunker Hill Sediment Characterization Study

    SciTech Connect

    Neal A. Yancey; Debby F. Bruhn

    2009-12-01

    The long history of mineral extraction in the Coeur d’Alene Basin has left a legacy of heavy metal laden mine tailings that have accumulated along the Coeur d’Alene River and its tributaries (U.S. Environmental Protection Agency, 2001; Barton, 2002). Silver, lead and zinc were the primary metals of economic interest in the area, but the ores contained other elements that have become environmental hazards including zinc, cadmium, lead, arsenic, nickel, and copper. The metals have contaminated the water and sediments of Lake Coeur d’Alene, and continue to be transported downstream to Spokane Washington via the Spokane River. In 1983, the EPA listed the Bunker Hill Mining and Metallurgical Complex on the National Priorities List. Since that time, many of the most contaminated areas have been stabilized or isolated, however metal contaminants continue to migrate through the basin. Designation as a Superfund site causes significant problems for the economically depressed communities in the area. Identification of primary sources of contamination can help set priorities for cleanup and cleanup options, which can include source removal, water treatment or no action depending on knowledge about the mobility of contaminants relative to water flow. The mobility of contaminant mobility under natural or engineered conditions depends on multiple factors including the physical and chemical state (or speciation) of metals and the range of processes, some of which can be seasonal, that cause mobilization of metals. As a result, it is particularly important to understand metal speciation (National Research Council, 2005) and the link between speciation and the rates of metal migration and the impact of natural or engineered variations in flow, biological activity or water chemistry.

  9. Description of Contaminant Sediment-Water Interactions Using RECOVERY

    DTIC Science & Technology

    1993-04-01

    with organic carbon ranging from 1.2 to 9 percent were selectea. They were Mark Twain Lake (Missouri), Louisville (Kentucky), Brown’s Lake (Mississippi...Percent Oakland Inner Wayne Louisville Mark Twain Harbor Brown’s Lake County Constituent Lake Sediment Lake Sediment Sediment Sediment Sand 10.0 45.0...of fine material than Mark Twain , Oakland Harbor, and Wayne County sediments (Table 1). Organic carbon content was higher in Wayne County, Brown’s

  10. Sustainably Managing Sediment in Regulated Rivers: Recent Developments

    NASA Astrophysics Data System (ADS)

    Kondolf, G. M.; Gao, Y.; Annandale, G. W.; Morris, G. L.; Sumi, T.

    2014-12-01

    Inspired by the current drought and concerns about maintaining water storage capacity, California State Senate this year passed SB1259, directing the Department of Water Resources to assess the state's reservoirs for sedimentation problems. The need to actively manage sediment in reservoirs is increasingly recognized, as valuable reservoir storage capacity is lost and downstream reaches suffer from sediment starvation, manifesting problems such as channel incision, accelerated erosion of deltas, and loss of gravels important for habitat. With increased dam construction globally, these impacts will be widespread. Despite the opportunities to pass sediment through or around reservoirs (to preserve reservoir capacity and to minimize downstream impacts), these sustainable approaches to managing sediment are not applied in many situations where they would be effective. From a workshop involving international and Chinese experts and review of recent literature, collective global experience in managing reservoir sediments and mitigating downstream sediment starvation suggest that sediment management can be classified as catchment management (to reduce sediment inflow), sediment removal, and sediment routing through or around the reservoir. Sediment routing has the virtues of maintaining sediment flows to downstream reaches, as well as preserving reservoir capacity. Where geometry is favorable, sediment can often be bypassed around the reservoir (avoiding reservoir sedimentation and supplying sediment to downstream reaches) or sluiced through large-capacity outlets after flowing rapidly through the reservoir to avoid sedimentation. In narrow reservoirs with steep longitudinal gradients, sediments accumulated in the reservoir can often be re-suspended and flushed through when the reservoir is drawn down. Turbidity currents can often be 'vented' through the dam, with the advantage that the reservoir need not be drawn down to pass sediment. In planning dams, the expert group

  11. Incorporation of Fine-Grained Sediment Erodibility Measurements into Sediment Transport Modeling, Capitol Lake, Washington

    USGS Publications Warehouse

    Stevens, Andrew W.; Gelfenbaum, Guy; Elias, Edwin; Jones, Craig

    2008-01-01

    Capitol Lake was created in 1951 with the construction of a concrete dam and control gate that prevented salt-water intrusion into the newly formed lake and regulated flow of the Deschutes River into southern Puget Sound. Physical processes associated with the former tidally dominated estuary were altered, and the dam structure itself likely caused an increase in retention of sediment flowing into the lake from the Deschutes River. Several efforts to manage sediment accumulation in the lake, including dredging and the construction of sediment traps upriver, failed to stop the lake from filling with sediment. The Deschutes Estuary Feasibility Study (DEFS) was carried out to evaluate the possibility of removing the dam and restoring estuarine processes as an alternative ongoing lake management. An important component of DEFS was the creation of a hydrodynamic and sediment transport model of the restored Deschutes Estuary. Results from model simulations indicated that estuarine processes would be restored under each of four restoration alternatives, and that over time, the restored estuary would have morphological features similar to the predam estuary. The model also predicted that after dam-removal, a large portion of the sediment eroded from the lake bottom would be deposited near the Port of Olympia and a marina located in lower Budd Inlet seaward of the present dam. The volume of sediment transported downstream was a critical piece of information that managers needed to estimate the total cost of the proposed restoration project. However, the ability of the model to predict the magnitude of sediment transport in general and, in particular, the volume of sediment deposition in the port and marina was limited by a lack of information on the erodibility of fine-grained sediments in Capitol Lake. Cores at several sites throughout Capitol Lake were collected between October 31 and November 1, 2007. The erodibility of sediments in the cores was later determined in the

  12. Large-scale suspended sediment transport and sediment deposition in the Mekong Delta

    NASA Astrophysics Data System (ADS)

    Manh, N. V.; Dung, N. V.; Hung, N. N.; Merz, B.; Apel, H.

    2014-08-01

    Sediment dynamics play a major role in the agricultural and fishery productivity of the Mekong Delta. However, the understanding of sediment dynamics in the delta, one of the most complex river deltas in the world, is very limited. This is a consequence of its large extent, the intricate system of rivers, channels and floodplains, and the scarcity of observations. This study quantifies, for the first time, the suspended sediment transport and sediment deposition in the whole Mekong Delta. To this end, a quasi-2D hydrodynamic model is combined with a cohesive sediment transport model. The combined model is calibrated using six objective functions to represent the different aspects of the hydraulic and sediment transport components. The model is calibrated for the extreme flood season in 2011 and shows good performance for 2 validation years with very different flood characteristics. It is shown how sediment transport and sediment deposition is differentiated from Kratie at the entrance of the delta on its way to the coast. The main factors influencing the spatial sediment dynamics are the river and channel system, dike rings, sluice gate operations, the magnitude of the floods, and tidal influences. The superposition of these factors leads to high spatial variability of sediment transport, in particular in the Vietnamese floodplains. Depending on the flood magnitude, annual sediment loads reaching the coast vary from 48 to 60% of the sediment load at Kratie. Deposited sediment varies from 19 to 23% of the annual load at Kratie in Cambodian floodplains, and from 1 to 6% in the compartmented and diked floodplains in Vietnam. Annual deposited nutrients (N, P, K), which are associated with the sediment deposition, provide on average more than 50% of mineral fertilizers typically applied for rice crops in non-flooded ring dike floodplains in Vietnam. Through the quantification of sediment and related nutrient input, the presented study provides a quantitative basis for

  13. Earthflow sediment production and Holocene sediment record in a large Apennine catchment

    NASA Astrophysics Data System (ADS)

    Simoni, Alessandro; Ponza, Alessio; Picotti, Vincenzo; Berti, Matteo; Dinelli, Enrico

    2013-04-01

    Landscape evolution in active mountain chains can be dominated by gravitational slope movements. This is observed in a large portion of the Reno river catchment, Apennines, Italy, where weak rocks, such as clayshales, are subject to earthflows that control hillslope morphology and supply sediments to the channel network. In this paper, we evaluate the sediment flux generated by earthflows and compare it with Holocene-averaged deposition rates to assess the contribution of mass movements to landscape evolution. Present-day hillslope sediment flux is estimated by combining measured displacement rates (72 inclinometers) and spatial attributes of earthflows and historical frequency of reactivations. Averaged sediment yield (~ 1.6 x 103 t/km2/yr) compares well with similar studies on earthflow-dominated landscapes, despite notable differences in methodology. In the study area, the connectivity between hillslopes and the stream network is well developed and no significant sediment sinks influence the sediment transport processes. We document best estimates of regional sediment fluxes and related uncertainties, based on available data. Coarse limestone fragments, present in the clayshales, are used as a natural sediment tracer to allow a comparison with sedimentation rates taking place at the mouth of the intramontane catchment. Here, available borehole logs, 14C datings and stratigraphic correlations of the alluvial fan are used to obtain an estimate of the deposition that took place during Holocene times. Taking also into account the role of solute transport, sedimentation rates are compared to earthflow sediment production rates. Results show a good agreement and demonstrate that earthflows are the primary mass wasting process in these weak rock lithologies. We document best estimates of regional sediment fluxes and related uncertainties. Present earthflow sediment production outpaces Holocene-averaged sedimentation rates by a factor of two. The gap between sediment

  14. Estimating suspended sediment loads in the Pearl River Delta region using sediment rating curves

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Wei, Xiaoyan; Jinhai, Zheng; Yuliang, Zhu; Zhang, Yanjing

    2012-04-01

    In this study, sediment rating curves are employed to study the variations in relationships between water discharge and suspended sediment concentration based on the recent 50 years of monthly data set in the three major rivers of the Pearl River Delta. Results show that sediment rating parameters vary with time. The lowest rating coefficient, ln(a), and the highest rating exponent, b, mostly occur in the 1980s, indicating that sediment transport reached its peak in this decade at the same level as water discharge. This upward shift of sediment load is probably caused by exacerbated karst rocky desertification in the upper reaches of the Pearl River. However, since the beginning of the 1990s sediment loads from the Pearl River to its estuary began to show a dramatically decreasing trend, which is attributed mainly to deposition in the reservoirs, leading to an increase of ln(a) and a decrease of b. Furthermore, the sediment rating curve in 1957 to1970 is applied to estimate potential sediment load (1971 to 2006) in the absence of human influences. It is also estimated quantitatively by the sediment rating curves that in the 1980s, the annual sediment load decreased by 7.59×106 t/yr because of natural factors, while sediment increase induced by human activities was 20.07×106 t/yr, which resulted in an actual increased sediment load of 12.47×106 t/yr compared with the reference level in 1957 to 1970. In the last two decades, the difference between measured and estimated sediment loads became considerable, and the annual deficit sharply increased to 26.80×106 t/yr in the 1990s, and 50.46×106 t/yr in the 2000s, indicating that human activities, mainly referring to dam and reservoir construction, play a dominant role in the decrease of sediment load. The decrease in sediment supply from the Pearl River should be paid special attention because it may cause serious impacts on the river delta and the coastal ocean.

  15. Dynamic sediment trapping and episodic sediment accretion in fluviodeltaic environments: Implications for coastal restoration

    NASA Astrophysics Data System (ADS)

    Shen, Z.; Tornqvist, T. E.; Chamberlain, E. L.; Esposito, C. R.; Marshak, J.; Nijhuis, A.; Sandoval, L.; Mauz, B.

    2013-12-01

    Many large river deltas are experiencing severe land loss because of various natural and anthropogenic causes. This is truly the case for the Mississippi Delta where ~40 km2/yr land loess have been documented for the last 25 years. A solid understanding about fluviodeltaic sediment dispersion and accretion is essential to improve management of fluviodeltaic landscapes. Here we present field data collected from the Bayou Lafourche subdelta in the Mississippi Delta to investigate the sedimentary and chronologic development of the Bayou Lafourche floodplain. The textural composition of the floodplain deposits shows dramatic changes along Bayou Lafourche. In the upstream portion where Bayou Lafourche cut through swamp environments, the floodplain deposits are dominantly mud, similar in composition to sediment load of the Lower Mississippi River. This suggests that the floodplain in this reach has a relatively high sediment trapping efficiency, which is confirmed by a >50% sediment trapping efficiency estimated for a crevasse splay there. In contrast, Bayou Lafourche floodplain deposits are sand dominant in the downstream portion where the subdelta extended into an open water environment, which suggests a relatively low sediment trapping efficiency in open water environments, similar to the Wax Lake Delta in the Mississippi Delta. Optical chronology for the Bayou Lafourche floodplain deposits demonstrates that fluviodeltaic sedimentation is episodic at a centennial time scale. As a consequence of relatively high sediment trapping efficiency and the episodic pattern of fluviodeltaic deposition, sediment accretion rates on the upstream portion of Bayou Lafourche are on the order of cm/yr at a centennial time scale. Our data suggest that mud, which constitutes ~80% of the Lower Mississippi River sediment load, can be used efficiently for wetland creation if being diverted to locations favor a high trapping efficiency, such as inland vegetated swamps. The sediment accretion

  16. Sediment properties influencing the bioavailability of uranium to Chironomus dilutus larvae in spiked field sediments.

    PubMed

    Crawford, Sarah E; Liber, Karsten

    2016-04-01

    The partitioning of metals between dissolved and solid phases directly affects metal bioavailability to benthic invertebrates and is influenced by metal-binding properties of sediment phases. Little research has been done examining the effects of sediment properties on the bioavailability of uranium (U) to freshwater benthic invertebrates. In the present study, 18 field sediments with a wide range of properties (total organic carbon, fine fraction, cation exchange capacity, and iron content) were amended with the same concentrations of U to characterize the effects of these sediment properties on U bioavailability to freshwater midge, Chironomus dilutus. Bioaccumulation of U by C. dilutus larvae varied by over an order of magnitude when exposed to sediments spiked with 50 mg U kg(-1) d.w. (5-69 mg U kg(-1) d.w.) and 500 mg U kg(-1) d.w. (20-452 mg U kg(-1) d.w.), depending on the type of sediment. Variance in U bioaccumulation was best explained by differences in the cation exchange capacity, fine fraction (≤50 μm particle size), and Fe content of U-spiked sediment, with generated regression equations predicting observed bioaccumulation within a factor of two. The presented regression equations offer an easy-to-apply method for accounting for the influence of sediment properties on U bioavailability in freshwater sediment, with fine fraction being the single most practical variable. This research strongly supports that risk assessments and guidelines for U-contaminated sediments should not ignore the influence of sediment properties that can result in substantial differences in the bioaccumulation of U in benthic invertebrates.

  17. Transitioning sediment quality assessment into regulations: Challenges and solutions in implementing California's sediment quality objectives.

    PubMed

    Beegan, Chris; Bay, Steven M

    2012-10-01

    Development and promulgation of sediment quality criteria represents a substantial challenge for water quality agencies. Unlike water quality programs that rely on individual chemical thresholds to assess water quality, the complex processes affecting contaminant bioavailability in sediments preclude the use of contaminant concentrations to independently assess impacts or identify cause. Various multiple line of evidence approaches (e.g., sediment quality triad) have been developed for sediment quality assessment, but such frameworks are rarely fully incorporated into statewide regulatory programs due to a lack of standardized and validated tools. In 2003, California's State Water Resources Control Board (State Water Board) initiated development of sediment quality criteria and an assessment framework that required the developers to resolve many challenging technical and policy related issues to the satisfaction of stakeholders, scientists, and the general public. The first part of this multiyear effort has been completed and resulted in the development and validation of an integrated collection of tools, thresholds, and a data interpretation framework for assessing sediment contamination impacts on benthic community condition. The State Water Board's narrative sediment quality criteria and assessment framework became effective in 2009, following US Environmental Protection Agency approval. The results of this effort are described in a series of 6 articles published in this issue of Integrated Environmental Assessment and Management. The articles describe: 1) a multiple line of evidence framework for data integration and assessment, 2) calibration and evaluation of sediment quality guidelines for predicting toxic responses, 3) development and evaluation of sediment quality guidelines with respect to benthic macrofauna responses, 4) selection of toxicity test methods and thresholds, 5) identification and characterization of benthic community assemblages, 6) the

  18. Utilizing Turbidity and Measurements of Suspended Sediment Concentrations to Better Understand Sediment Transport within Urban Streams

    NASA Astrophysics Data System (ADS)

    Elkins, T. M.; Napieralski, J. A.

    2009-12-01

    The Rouge River watershed in Southeast Michigan is an urban watershed, which has been exposed to more than 100 years of anthropogenic activities related to industrialization and urbanization. This urbanization has degraded water quality by increasing erosion and altering the transport mechanism and chemistry of bed and suspended sediments. This study aims to explore the relationship between development within the Lower Rouge watershed and watershed hydrology through an examination of USGS discharge data, stream water quality and suspended sediment loads during storm and base flow. Two YSI dataloggers are used to continuously measure water quality parameters during baseflow and storm events (varying hydrologic conditions), including: turbidity, dissolved oxygen, conductivity, salinity, total dissolved solids, and temperature. Depth-integrated sediment samples are collected and analyzed for sediment concentration using Imhoff cones and filtration methods. Correlations between discharge weighted continuous turbidity measurements and discharge weighted suspended sediment samples are used to estimate sediment loads; essentially, turbidity readings and measured sediment concentrations form a near-linear relationship. In addition, sediment samples are analyzed for inorganic heavy metal contaminants common to Southeast Michigan to characterize both suspended sediments and sediments frequently deposited on adjacent floodplains. These metals (i.e. Lead, Copper, Chromium, Nickle) are commonly known as the “Michigan Metals” and represent indicator species of mobilized and deposited contaminants associated with urbanization and industrialization. The results will provide a baseline for better understanding the transport and fate of contaminated sediments within the Rouge watershed, as well as guide ongoing development and management practices along the Rouge River.

  19. Mercury in sediments of Ulhas estuary.

    PubMed

    Ram, Anirudh; Rokade, M A; Borole, D V; Zingde, M D

    2003-07-01

    Hg levels in water, suspended particulate matter and sediment of the Ulhas estuary are under considerable environmental stress due to the indiscriminate release of effluents from a variety of industries including chlor-alkali plants. Concentration ranges of dissolved (0.04-0.61 micro gl(-1)) and particulate (1.13-6.43 micro gg(-1)) Hg reveal a definite enhancement of levels in the estuary. The Hg burden in sediment upstream of the weir that limits the tidal influence is low (0.08-0.19 micro gg(-1)) with low C(org) content (1.8-2.9%). The high Hg content of the sediment just below the weir varies seasonally (highest concentration recorded being 38.45 micro gg(-1)) due to incremental accretion of sediment as the fresh water flow over the weir progressively decreases. The 30 km segment of the estuary sustains markedly high levels of Hg in the sediment with an exponential decrease in the seaward direction from the weir. Higher concentrations than the expected background prevail in all the estuarine cores up to the bottom, though the overall concentration decreases from about 20 micro gg(-1) in core 7 (inner estuary) to 1 micro gg(-1) in core 31 (outer estuary). The Hg in sediment is associated with C(org), while its correlation with Al, Fe and Mn is poor. The Hg profiles in cores from the Arabian Sea (stations 34, 35 and 37) have a distinct horizon of enhanced concentration in the 5-60 cm segment. Based on 210Pb dating of core 37, the sediment at the bottom of this core is inferred to have been deposited in the year 1949, roughly two year prior to the establishment of the first chlor-alkali plant and represents the background (0.06-0.10 micro gg(-1)). The Hg profiles in the offshore cores indicate a marked increase in transfer of Hg to sediment subsequent to 1980, with a peak around 1990-1992. Based on the index of geoaccumulation it is considered that the estuarine segment between stations 4 and 23 is extremely polluted, while the sediment from the open coast is

  20. Mercury in Long Island Sound sediments

    USGS Publications Warehouse

    Varekamp, J.C.; Bucholtz ten Brink, M. R.; Mecray, E.I.; Kreulen, B.

    2000-01-01

    Mercury (Hg) concentrations were measured in 394 surface and core samples from Long Island Sound (LIS). The surface sediment Hg concentration data show a wide spread, ranging from 600 ppb Hg in westernmost LIS. Part of the observed range is related to variations in the bottom sedimentary environments, with higher Hg concentrations in the muddy depositional areas of central and western LIS. A strong residual trend of higher Hg values to the west remains when the data are normalized to grain size. Relationships between a tracer for sewage effluents (C. perfringens) and Hg concentrations indicate that between 0-50 % of the Hg is derived from sewage sources for most samples from the western and central basins. A higher percentage of sewage-derived Hg is found in samples from the westernmost section of LIS and in some local spots near urban centers. The remainder of the Hg is carried into the Sound with contaminated sediments from the watersheds and a small fraction enters the Sound as in situ atmospheric deposition. The Hg-depth profiles of several cores have well-defined contamination profiles that extend to pre-industrial background values. These data indicate that the Hg levels in the Sound have increased by a factor of 5-6 over the last few centuries, but Hg levels in LIS sediments have declined in modern times by up to 30 %. The concentrations of C. perfringens increased exponentially in the top core sections which had declining Hg concentrations, suggesting a recent decline in Hg fluxes that are unrelated to sewage effluents. The observed spatial and historical trends show Hg fluxes to LIS from sewage effluents, contaminated sediment input from the Connecticut River, point source inputs of strongly contaminated sediment from the Housatonic River, variations in the abundance of Hg carrier phases such as TOC and Fe, and focusing of sediment-bound Hg in association with westward sediment transport within the Sound.

  1. Shifting Sediment Sources in the Quaternary Nile

    NASA Astrophysics Data System (ADS)

    Woodward, Jamie; Macklin, Mark; Fielding, Laura; Millar, Ian; Williams, Martin

    2016-04-01

    Invited Paper The Nile basin contains the longest river channel system in the world and drains about one tenth of the African continent. A dominant characteristic of the modern Nile is the marked spatial and temporal variability in the flux of water and sediment. Because the major headwater basins of the Nile are linked to key elements of the global climate system, the sedimentary records in the basin have attracted good deal of attention from the Quaternary palaeoclimate and palaeohydrology communities. Various approaches (from heavy minerals to strontium isotopes) have been employed to examine present and past patterns of sediment yield in the basin. A good deal of work has been carried out on the long sediment records in the delta and offshore which provide high resolution archives of hydrological changes in the upstream basin as well fluctuations in the input of dust from the desert. The sediment load of the modern desert Nile (downstream of Khartoum) is dominated by sediment inputs from the Blue Nile (61 +/- 5%) and Atbara (35 +/- 4%), whilst the White Nile contribution is meagre (3 +/- 2%) (Padoan et al. 2011). Recent work has shown that these values were very different during humid phases of the Quaternary when stronger Northern Hemisphere summer insolation produced wetter conditions across North Africa. In the early Holocene, for example, the Nile floodplain in Northern Sudan shows a tributary wadi input of 40-50%. This paper will review three decades of work on the sediment delivery dynamics of the Quaternary Nile and explore their palaeoclimatic implications. Padoan, M., Garzanti, E., Harlavan, Y., Villa, I.M. (2011) Tracing Nile sediment sources by Sr and Nd isotope signatures (Uganda, Ethiopia, Sudan). Geochim. Cosmochim. Acta 75 (12), 3627-3644.

  2. A numerical investigation of convective sedimentation

    NASA Astrophysics Data System (ADS)

    Snyder, Patrick J.; Hsu, Tian-Jian

    2011-09-01

    Understanding the fate of riverine sediment in the coastal environment is critical to the health of the coastal ecosystem and the changing morphology. One of the least understood mechanisms of initial deposition is the convective sedimentation of hypopycnal plumes. This study aims at investigating convective sedimentation by means of a numerical model for fine sediment transport solving the non-hydrostatic Reynolds-averaged Navier-Stokes equations for stratified turbulent flow. Model validation is sought by comparison to laboratory results for turbidity and saline currents over a changing slope. The model is shown to be capable of predicting both the upstream supercritical and the downstream subcritical flows. The numerical model is then utilized to study convective sedimentation and its depositional and mixing characteristics. By analyzing model results of more than 40 runs for different inlet sediment concentration (density ratio γ), settling velocity (particle Reynolds number Rep), and inlet velocity/height (inlet Reynolds number Re), four distinct flow regimes are revealed. For large γ, we observe divergent plumes with significant deposits near the inlet. For intermediate γ and large Rep, intense convective fingers are predicted which are only marginally affected by ambient shear flow. Further reducing the density ratio γ or Rep gives weak convective fingers that are significantly affected by the ambient shear flow. Eventually, no convective fingers are observed during the computation for very small γ or Rep. Sediment deposits in the divergent plume and intense convective finger regimes are relatively insensitive to Re. Deposit increases with Re in the weak convective finger regime.

  3. Magnetic seeding sedimentation (MSS) of coal slimes

    NASA Astrophysics Data System (ADS)

    Wu, Xiqing; Yue, Tao; Dai, Liang

    2017-01-01

    Magnetic seeding sedimentation (MSS), i.e. adding magnetic seeds and pre-magnetization for sedimentation, is a technique especially for sedimentation of fine slimes, improving the sedimentation performance by introducing the magnetic interactions between particles in a suspension and enlarging the apparent size of the fine particles. The fine coal slimes with a size of 66.68%-38μm were investigated by the MSS. Sedimentation tests were conducted, and some measurements, such as laser size analysis, magnetic susceptibility by vibrating sample magnetometer (VSM), were also applied in order to probe the mechanism of the MSS. Based on the tests, measurements and calculations it was demonstrated that the sedimentation of coal slimes increased with the additions of the magnetic seeds, and in the presence of the polyacrylamide, and also there appeared a relatively large apparent size of slimes after additions of magnetic seeds and/or polyacrylamide. So, the reason for the influence of MSS lies in fact that the presence of the polyacrylamide intensified the adsorption of magnetic seeds on the coal particles and the coverage of the magnetic seeds on the coal surface from 0.2% wt. to1.3% wt., resulting in increased magnetic susceptibility of coal particles from 9.13×10-9m3/kg to 22.17×10-9m3/kg and thus a low magnetic field strength of pre-magnetization needed for the magnetic agglomeration to happen among the coal particles (the threshold of magnetic field strength for agglomeration) from 602mT to 24mT prior to proper sedimentation.

  4. Tsunami inundation and sediment transport in a sediment-limited embayment on American Samoa

    USGS Publications Warehouse

    Apotsos, A.; Gelfenbaum, G.; Jaffe, B.; Watt, Sebastian; Peck, B.; Buckley, M.; Stevens, A.

    2011-01-01

    Field observations and numerical simulations are used to explore tsunami inundation and sediment transport in an embayment (Fagafue Bay) on the north side of Tutuila, American Samoa during the 29 September 2009 South Pacific tsunami. Field observations of the nearshore bathymetry and topography, tsunami flow depth and sediment deposition, and extent of movable sandy sediment remaining on the beach were collected during two field surveys approximately two and five weeks after the tsunami. Onshore measurements of flow depth at forty-eight locations indicate the wave inundated almost 250. m onshore with a depth exceeding 7. m locally. The tsunami deposited patchy areas of sediment up to 0.2. m thick interspersed with a thin dusting (< 0.01 m) of sandy sediment throughout most of the inundated area. A numerical simulation based on the best available topography and bathymetry and a simplified offshore wave forcing is calibrated with the onshore flow observations. The calibrated model is used to simulate tsunami-induced sediment transport within and onshore of both the actual embayment and several idealized embayments. The simulations show that the onshore deposition of sediment can be affected by more than 50% by both the amount of sediment available for transport and the steepness of the onshore topography, suggesting these effects may need to be considered when interpreting tsunami deposits.

  5. A COMPARISON OF BULK SEDIMENT TOXICITY TESTING METHODS AND SEDIMENT ELUTRIATE TOXICITY

    EPA Science Inventory

    Bulk sediment toxicity tests are routinely used to assess the level and extent of contamination in natural sediments. While reliable, these tests can be resource intensive, requiring significant outlays of time and materials. The purpose of this study was to compare the results ...

  6. EMAP SEDIMENTATION INDEX: LAND USE AND NATURAL HYDRAULIC CONTROLS ON STREAM SEDIMENTATION

    EPA Science Inventory

    Excessive erosion, transport and deposition of sediment in streams and rivers is a major problem in surface waters throughout the United States. It is important to have a reliable measure of stream sedimentation that properly accounts for natural controls on the amount of fine p...

  7. Nature and changes in organic matter in organic sediments. [organic matter in ocean sediments

    NASA Technical Reports Server (NTRS)

    Kaplan, I. R.

    1973-01-01

    A series of isoprenoid compounds were isolated from a heat treated marine sediment (from Tanner Basin) which were not present in the original sediment. Among the compounds identified were: phytol, dihydrophytol, C-18-isoprenoid ketone, phytanic and pristanic acids, C-19- and C-10-monoolefines, and the alkanes pristane and phytane. The significance and possible routes leading to these compounds is discussed.

  8. PREDICTING SEDIMENT METAL TOXICITY USING A SEDIMENT BIOTIC LIGAND MODEL: METHODOLOGY AND INITIAL APPLICATION

    EPA Science Inventory

    An extension of the simultaneously extracted metals/acid-volatile sulfide (SEM/AVS) procedure is presented that predicts the acute and chronic sediment metals effects concentrations. A biotic ligand model (BLM) and a pore water–sediment partitioning model are used to predict the ...

  9. Mechanistic Sediment Quality Guidelines Based on Contaminant Bioavailability: Equilibrium Partitioning Sediment Benchmarks

    EPA Science Inventory

    Globally, billions of metric tons of contaminated sediments are present in aquatic systems representing a potentially significant ecological risk. Estimated costs to manage (i.e., remediate and monitor) these sediments are in the billions of U.S. dollars. Biologically-based app...

  10. Reservoir Sedimentation and Upstream Sediment Sources: Perspectives and Future Research Needs on Streambank and Gully Erosion

    NASA Astrophysics Data System (ADS)

    Fox, G. A.; Sheshukov, A.; Cruse, R.; Kolar, R. L.; Guertault, L.; Gesch, K. R.; Dutnell, R. C.

    2016-05-01

    The future reliance on water supply and flood control reservoirs across the globe will continue to expand, especially under a variable climate. As the inventory of new potential dam sites is shrinking, construction of additional reservoirs is less likely compared to simultaneous flow and sediment management in existing reservoirs. One aspect of this sediment management is related to the control of upstream sediment sources. However, key research questions remain regarding upstream sediment loading rates. Highlighted in this article are research needs relative to measuring and predicting sediment transport rates and loading due to streambank and gully erosion within a watershed. For example, additional instream sediment transport and reservoir sedimentation rate measurements are needed across a range of watershed conditions, reservoir sizes, and geographical locations. More research is needed to understand the intricate linkage between upland practices and instream response. A need still exists to clarify the benefit of restoration or stabilization of a small reach within a channel system or maturing gully on total watershed sediment load. We need to better understand the intricate interactions between hydrological and erosion processes to improve prediction, location, and timing of streambank erosion and failure and gully formation. Also, improved process-based measurement and prediction techniques are needed that balance data requirements regarding cohesive soil erodibility and stability as compared to simpler topographic indices for gullies or stream classification systems. Such techniques will allow the research community to address the benefit of various conservation and/or stabilization practices at targeted locations within watersheds.

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

    PubMed Central

    Tenzer, R.; Gladkikh, V.

    2014-01-01

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

  12. Activities and geochronology of (137)Cs in lake sediments resulting from sediment resuspension.

    PubMed

    Matisoff, Gerald

    2017-02-01

    In lakes with a large surface area to watershed ratio (137)Cs delivery is primarily by direct atmospheric fallout to the lake surface, where its activity in the sediments has been used to estimate the exposure to organisms and sediment mass deposition rates. Comparison of (137)Cs in the historical atmospheric fallout record with (137)Cs activity profiles in sediment cores reveals that although the general features of a maxima in the fallout deposition can be matched to activity peaks in the core, the general shape of the (137)Cs profile is not an exact replica of the fallout history. Instead, the sediment reflects post-depositional processes such as resuspension, bioturbation, partitioning of (137)Cs between the sediment solids and the pore fluids, and molecular diffusion of (137)Cs through the pore fluids. Presented here is a model that couples these processes to a system time averaging (STA) model that accounts for the time history of (137)Cs fallout and the particle residence time in the water column or in the 'active' surface sediment subject to resuspension. Sediment profiles are examined by comparing reasonable ranges of each of the coefficients of each of these major processes and by applying the model to cores collected from two large, shallow lakes, Lake Erie (USA/Canada) and Lake Winnipeg (Canada). The results indicate that the STA model with molecular diffusion and sediment resuspension best describes the data from these large, shallow lakes.

  13. Reservoir Sedimentation and Upstream Sediment Sources: Perspectives and Future Research Needs on Streambank and Gully Erosion.

    PubMed

    Fox, G A; Sheshukov, A; Cruse, R; Kolar, R L; Guertault, L; Gesch, K R; Dutnell, R C

    2016-05-01

    The future reliance on water supply and flood control reservoirs across the globe will continue to expand, especially under a variable climate. As the inventory of new potential dam sites is shrinking, construction of additional reservoirs is less likely compared to simultaneous flow and sediment management in existing reservoirs. One aspect of this sediment management is related to the control of upstream sediment sources. However, key research questions remain regarding upstream sediment loading rates. Highlighted in this article are research needs relative to measuring and predicting sediment transport rates and loading due to streambank and gully erosion within a watershed. For example, additional instream sediment transport and reservoir sedimentation rate measurements are needed across a range of watershed conditions, reservoir sizes, and geographical locations. More research is needed to understand the intricate linkage between upland practices and instream response. A need still exists to clarify the benefit of restoration or stabilization of a small reach within a channel system or maturing gully on total watershed sediment load. We need to better understand the intricate interactions between hydrological and erosion processes to improve prediction, location, and timing of streambank erosion and failure and gully formation. Also, improved process-based measurement and prediction techniques are needed that balance data requirements regarding cohesive soil erodibility and stability as compared to simpler topographic indices for gullies or stream classification systems. Such techniques will allow the research community to address the benefit of various conservation and/or stabilization practices at targeted locations within watersheds.

  14. Development of a standardized sediment reference toxicant test using formulated sediment and copper sulfate

    SciTech Connect

    Suedel, B.C.; Hartzell, R.S.; Williams, C.W.; Connelly, R.A.

    1994-12-31

    The lack of suitable reference toxicant tests to assess the condition or health of populations of benthic test organisms is problematic because the precision and accuracy of definitive whole sediment tests cannot be assessed without this reference. To address this need, formulated sediment was prepared to provide a consistent substrate with respect to percent solids, particle size distribution, cation exchange capacity, organic carbon, organic matter, redox potential, and pH. Hyalella azteca and Chironomus tentans were exposed for 96-h to formulated sediment amended with serial dilutions of copper sulfate. Results indicate that (1) formulated sediments can be prepared consistently between batches with minimal variability with respect to sediment characteristics, providing a consistent test substrate; (2) when combined with formulated sediment, copper sulfate is a suitable sediment reference toxicant for assessing the condition and health of H. azteca and C tentans populations; and (3) formulated sediment provides a suitable substrate for H. azteca and C tentans (control survival > 80%). This method provides a means by which the health and sensitivity of benthic test organisms can be assessed and provides a measure of precision within and among laboratories through time.

  15. Pollutants' Release, Redistribution and Remediation of Black Smelly River Sediment Based on Re-Suspension and Deep Aeration of Sediment.

    PubMed

    Zhu, Lin; Li, Xun; Zhang, Chen; Duan, Zengqiang

    2017-04-01

    Heavily polluted sediment is becoming an important part of water pollution, and this situation is particularly acute in developing countries. Sediment has gradually changed from being the pollution adsorbent to the release source and has influenced the water environment and public health. In this study, we evaluated the pollutant distribution in sediment in a heavily polluted river and agitated the sediment in a heavily polluted river to re-suspend it and re-release pollutants. We found that the levels of chemical oxygen demand (COD), NH₄⁺-N, total nitrogen (TN), and total phosphorus (TP) in overlying water were significantly increased 60 min after agitation. The distribution of the pollutants in the sediment present high concentrations of pollutants congregated on top of the sediment after re-settling, and their distribution decreased with depth. Before agitation, the pollutants were randomly distributed throughout the sediment. Secondly, deep sediment aeration equipment (a micro-porous air diffuser) was installed during the process of sedimentation to study the remediation of the sediment by continuous aeration. The results revealed that deep sediment aeration after re-suspension significantly promoted the degradation of the pollutants both in overlying water and sediment, which also reduced the thickness of the sediment from 0.9 m to 0.6 m. Therefore, sediment aeration after suspension was efficient, and is a promising method for sediment remediation applications.

  16. Degradation rates of low molecular weight PAH correlate with sediment TOC in marine subtidal sediments.

    PubMed

    Hinga, K R

    2003-04-01

    The degradation rate of low molecular weight (LMW) polycyclic aromatic hydrocarbons (PAH) in subtidal marine sediments was found to correlate with sediment total organic carbon (TOC) in stations sampled two or more times after the North Cape No. 2 fuel oil spill. With 2.5-5 months between samplings, stations with lower sediment TOC had lower fractions of LMW PAH remaining at the time of the second sampling. Apparent first-order degradation rate constants calculated for each station varied by nearly an order of magnitude between stations with a range of TOC from 0.4% to 7.3%. The correlation of degradation rate with sediment TOC can be used to provide improved and site-specific predictions of the initial time-course of LMW PAH concentrations in sediments after oil spills.

  17. Applying sediment quality guidelines on soft sediments of the Gulf of Finland, Baltic Sea.

    PubMed

    Vallius, Henry

    2015-09-15

    The Gulf of Finland is known to have been rather largely contaminated by heavy metals during the last half of the 20th century, but indications of recovery have been reported. In order to investigate the recent levels of heavy metals and arsenic in the uppermost soft sediments of the off-shore Gulf of Finland coring of altogether 23 sites were performed. The subsamples of the cores are 605 in total and thus give a good picture of heavy metal levels in the surface sediments during the first decade of this century. In order to evaluate methods and predict sediment toxicity the sediment concentrations are compared to American SQG:s. Majority of the subsamples exceeded the threshold levels of both used SQG:s, but some exceeded also the midrange effects quality guidelines. As, Cd, Hg, and Zn concentrations still occur at unacceptably high levels in sediments of the off-shore Gulf of Finland.

  18. Sediment Burial Intolerance of Marine Macroinvertebrates.

    PubMed

    Hendrick, Vicki J; Hutchison, Zoë L; Last, Kim S

    2016-01-01

    The marine environment contains suspended particulate matter which originates from natural and anthropogenic sources. Settlement of this material can leave benthic organisms susceptible to smothering, especially if burial is sudden i.e. following storms or activities such as dredging. Their survival will depend on their tolerance to, and their ability to escape from burial. Here we present data from a multi-factorial experiment measuring burial responses incorporating duration, sediment fraction and depth. Six macroinvertebrates commonly found in sediment rich environments were selected for their commercial and/or conservation importance. Assessments revealed that the brittle star (Ophiura ophiura), the queen scallop (Aequipecten opercularis) and the sea squirt (Ciona intestinalis) were all highly intolerant to burial whilst the green urchin (Psammichinus miliaris) and the anemone (Sagartiogeton laceratus), showed intermediate and low intolerance respectively, to burial. The least intolerant, with very high survival was the Ross worm (Sabellaria spinulosa). With the exception of C. intestinalis, increasing duration and depth of burial with finer sediment fractions resulted in increased mortality for all species assessed. For C. intestinalis depth of burial and sediment fraction were found to be inconsequential since there was complete mortality of all specimens buried for more than one day. When burial emergence was assessed O. ophiura emerged most frequently, followed by P. miliaris. The former emerged most frequently from the medium and fine sediments whereas P. miliaris emerged more frequently from coarse sediment. Both A. opercularis and S. laceratus showed similar emergence responses over time, with A. opercularis emerging more frequently under coarse sediments. The frequency of emergence of S. laceratus increased with progressively finer sediment and C. intestinalis did not emerge from burial irrespective of sediment fraction or depth. Finally, and perhaps

  19. Sediment Burial Intolerance of Marine Macroinvertebrates

    PubMed Central

    Hendrick, Vicki J.; Hutchison, Zoë L.; Last, Kim S.

    2016-01-01

    The marine environment contains suspended particulate matter which originates from natural and anthropogenic sources. Settlement of this material can leave benthic organisms susceptible to smothering, especially if burial is sudden i.e. following storms or activities such as dredging. Their survival will depend on their tolerance to, and their ability to escape from burial. Here we present data from a multi-factorial experiment measuring burial responses incorporating duration, sediment fraction and depth. Six macroinvertebrates commonly found in sediment rich environments were selected for their commercial and/or conservation importance. Assessments revealed that the brittle star (Ophiura ophiura), the queen scallop (Aequipecten opercularis) and the sea squirt (Ciona intestinalis) were all highly intolerant to burial whilst the green urchin (Psammichinus miliaris) and the anemone (Sagartiogeton laceratus), showed intermediate and low intolerance respectively, to burial. The least intolerant, with very high survival was the Ross worm (Sabellaria spinulosa). With the exception of C. intestinalis, increasing duration and depth of burial with finer sediment fractions resulted in increased mortality for all species assessed. For C. intestinalis depth of burial and sediment fraction were found to be inconsequential since there was complete mortality of all specimens buried for more than one day. When burial emergence was assessed O. ophiura emerged most frequently, followed by P. miliaris. The former emerged most frequently from the medium and fine sediments whereas P. miliaris emerged more frequently from coarse sediment. Both A. opercularis and S. laceratus showed similar emergence responses over time, with A. opercularis emerging more frequently under coarse sediments. The frequency of emergence of S. laceratus increased with progressively finer sediment and C. intestinalis did not emerge from burial irrespective of sediment fraction or depth. Finally, and perhaps

  20. Sediment fluxes in transboundary Selenga river basin

    NASA Astrophysics Data System (ADS)

    Belozerova, Ekaterina

    2013-04-01

    Gathering reliable information on transboundary river systems remains a crucial task for international water management and environmental pollution control. Countries located in the lower parts of the river basins depend on water use and management strategies in adjacent upstream countries. One important issue in this context is sediment transport and associated contaminant fluxes across the state borders. The mass flows of dissolved ions, biogens, heavy metal concentrations, as far as suspended sediment concentration (SSC, mg/l) along upper Selenga river and its tributaries based on the literature review and results of field campaigns 2011-2012 were estimated. Based on the water discharges measurements Q, suspended load WR (t/day) and dissolved loads WL were calculated. In the Selenga basin the minimal WR (1,34-3,74 t/day) were found at small rivers. Maximal sediment loads (WR = 15 000 t/day) were found at the upper Orkhon river during flood event. The downstream point (Mongolia-Russia border) was characterized 2 220 t/day in 2011. Generally the prevalence of the accumulation is found through calculating sediment budget for all rivers (ΔW = WR (downstream) - WR (upstream) < 0). Downstream of Orkhon river (below confluence with Tuul) ΔW = - 1145 t/day. Below Selenga-Orkhon confluence sediment yield reached 2515 t/day, which is corresponded to transboundary sediment flux. Silt sediments (0,001 - 0,05 mm) form the main portion of the transported material. The maximal value of sand flux (302 t/day) was reported for middle stream station of Selenga river (upstream from confluence with Orkhon). The increase of human activities (mining and pastures) increases the portion of clay particles in total sediment load (e.g. at the downstream point of most polluted Orkhon river it reached 207,8 t/day). The existed estimates are compared with distribution of the main matter sources within basin: mining and industry, river-bank erosion and slope wash. The heaviest increase of

  1. Using Distributed Continuous Turbidity Monitoring to Inform Sediment and Sediment-bound Nutrient Budgets

    NASA Astrophysics Data System (ADS)

    Rizzo, D.; Hamshaw, S. D.; Underwood, K. L.; Wemple, B. C.; Dewoolkar, M.

    2014-12-01

    The State of Vermont is experiencing changing hydrological regimes due to increased precipitation resulting from climate change. Understanding the impacts this change may cause to river corridors and the water quality of receiving waters is a critical need. Estimating the loading of sediment and sediment-bound nutrients such as phosphorous from various sources is a key aspect. In particular, the proportion attributable to main stem bank erosion is of concern as it is suspected to be a significant source in river basins in the Northeast. Sediment and nutrient budgets have been utilized for many years to provide a conceptual framework for proportioning loading to different sources. In this study, a continuous turbidity monitoring station network informs the creation of a watershed sediment budget in a small watershed. Monitoring stations placed on select upstream tributaries as well as the downstream watershed outlet are used to characterize overall watershed yield as well as loading to the main stem from tributaries. Analysis of differential unit area loading from tributary and downstream monitoring sites estimate the proportion of the overall watershed sediment yield that could be attributed to main stem bank erosion. Regression models of suspended sediment and total phosphorous enable the quantification of sediment-bound phosphorous loadings from stream banks. To characterize loadings and overall watershed sediment and nutrient yields, a probabilistic framework is created using a Bayesian approach that enables updating of continuously-collected data and provides estimates of uncertainty resulting in credible ranges of sediment and phosphorous loading. These sediment and nutrient budget estimates along with their associated uncertainties help inform water resource managers of loading sources and enable prioritization of mitigation efforts.

  2. Anaerobic biodegradation of hexazinone in four sediments.

    PubMed

    Wang, Huili; Xu, Shuxia; Tan, Chengxia; Wang, Xuedong

    2009-05-30

    Anaerobic biodegradation of hexazinone was investigated in four sediments (L1, L2, Y1 and Y2). Results showed that the L2 sediment had the highest biodegradation potential among four sediments. However, the Y1 and Y2 sediments had no capacity to biodegrade hexazinone. Sediments with rich total organic carbon, long-term contamination history by hexazinone and neutral pH may have a high biodegradation potential because the former two factors can induce the growth of microorganisms responsible for biodegradation and the third factor can offer suitable conditions for biodegradation. The addition of sulfate or nitrate as electron acceptors enhanced hexazinone degradation. As expected, the addition of electron donors (lactate, acetate or pyruvate) substantially inhibited the degradation. In natural environmental conditions, the effect of intermediate A [3-(4-hydroxycyclohexyl)-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H, 3H)dione] on anaerobic hexazinone degradation was negligible because of its low level.

  3. Sedimentation coefficient distributions of large particles.

    PubMed

    Schuck, Peter

    2016-07-21

    The spatial and temporal evolution of concentration boundaries in sedimentation velocity analytical ultracentrifugation reports on the size distribution of particles with high hydrodynamic resolution. For large particles such as large protein complexes, fibrils, viral particles, or nanoparticles, sedimentation conditions usually allow migration from diffusion to be neglected relative to sedimentation. In this case, the shape of the sedimentation boundaries of polydisperse mixtures relates directly to the underlying size-distributions. Integral and derivative methods for calculating sedimentation coefficient distributions g*(s) of large particles from experimental boundary profiles have been developed previously, and are recapitulated here in a common theoretical framework. This leads to a previously unrecognized relationship between g*(s) and the time-derivative of concentration profiles. Of closed analytical form, it is analogous to the well-known Bridgman relationship for the radial derivative. It provides a quantitative description of the effect of substituting the time-derivative by scan differences with finite time intervals, which appears as a skewed box average of the true distribution. This helps to theoretically clarify the differences between results from time-derivative method and the approach of directly fitting the integral definition of g*(s) to the entirety of experimental boundary data.

  4. Mesoscale eddies transport deep-sea sediments.

    PubMed

    Zhang, Yanwei; Liu, Zhifei; Zhao, Yulong; Wang, Wenguang; Li, Jianru; Xu, Jingping

    2014-08-04

    Mesoscale eddies, which contribute to long-distance water mass transport and biogeochemical budget in the upper ocean, have recently been taken into assessment of the deep-sea hydrodynamic variability. However, how such eddies influence sediment movement in the deepwater environment has not been explored. Here for the first time we observed deep-sea sediment transport processes driven by mesoscale eddies in the northern South China Sea via a full-water column mooring system located at 2100 m water depth. Two southwestward propagating, deep-reaching anticyclonic eddies passed by the study site during January to March 2012 and November 2012 to January 2013, respectively. Our multiple moored instruments recorded simultaneous or lagging enhancement of suspended sediment concentration with full-water column velocity and temperature anomalies. We interpret these suspended sediments to have been trapped and transported from the southwest of Taiwan by the mesoscale eddies. The net near-bottom southwestward sediment transport by the two events is estimated up to one million tons. Our study highlights the significance of surface-generated mesoscale eddies on the deepwater sedimentary dynamic process.

  5. Flux saturation length of sediment transport

    NASA Astrophysics Data System (ADS)

    Pähtz, T.; Kok, J. F.

    2013-12-01

    Sediment transport along the surface ("bedload", "saltation") drives geophysical phenomena as diverse as wind erosion and dune formation. The main length-scale controlling the dynamics of sediment erosion and deposition is the saturation length L, which characterizes the flux response to a change in transport conditions. L partially determines the dynamics of bedforms, such as dunes, for instance by dictating the wavelength of elementary dunes on a sediment surface and the minimal size of crescent-shaped barchan dunes. Here, we present an analytical model predicting L as a function of the average sediment velocity under different physical environments. Our model accounts for both the characteristics of sediment entrainment and the saturation of particle and fluid velocities, and has only two physical parameters which we estimated directly from independent experiments. We show that our model is consistent with measurements of L in both aeolian and subaqueous transport regimes over at least five orders of magnitude in the ratio of fluid and particle density, including on Mars.

  6. Sedimentation profiles in Lake Tuscaloosa, Alabama, 2000

    USGS Publications Warehouse

    Stricklin, Victor E.

    2001-01-01

    Lake Tuscaloosa, created in 1969 by the impoundment of North River, is the primary water supply for the cities of Tuscaloosa and Northport, Alabama, and surrounding areas. In 1982, 17 cross-sections were established in the principal tributaries of the lake, which include North River, Dry Creek, Turkey Creek, Binion Creek, Tierce Creek, Carroll Creek, and Brush Creek. These cross-sections were resurveyed in 1986 to determine the amount of sedimentation or scour occurring in the lake at these areas. In May 2000, 14 of the 17 cross-sections were located for resurveying to determine the amount of sedimentation or scour since 1986. The maximum amount of sediment deposition determined from the 2000 survey occurred in the upper end of the Carroll Creek tributary at cross-section CC8 (3.0 feet). The maximum amount of scour occurred in the Turkey Creek tributary at cross-section TRC2 (7.0 feet). Of the 14 cross-sections, 6 indicated increased amounts of sediment deposition, 5 indicated scouring of bottom sediments, and 3 indicated little or no change.

  7. Amyloplast sedimentation kinetics in gravistimulated maize roots

    NASA Technical Reports Server (NTRS)

    Sack, F. D.; Suyemoto, M. M.; Leopold, A. C.

    1985-01-01

    Amyloplast sedimentation in gravistimulated maize (Zea mays L.) roots was measured using the change in angle from the center of the cell to each amyloplast as an index of sedimentation. Using tissue fixed after gravistimulation, the relationship between mean amyloplast angle and the duration of gravistimulation was found to be linear when plotted on a logarithmic time scale. Extrapolated values for the onset of angular change are 5.9 s after the start of gravistimulation for the entire population of amyloplasts and 11.8 s for lead amyloplasts. By multiplying the instantaneous angular velocity (in radians) by the cell center to amyloplast radius, it is possible to calculate the initial sedimentation velocity to be 19.1 micrometers min-1 at 5.9 s. During sedimentation, the mean amyloplast angles surpass the calculated cell corner angle of 123 at 2.2 min for all amyloplasts and at 19 s for lead amyloplasts near the new lower wall. Thus, substantial sedimentation occurs within the presentation time, calculated to be 4.1 min. These kinetics are consistent with several hypotheses of graviperception.

  8. Sediment isotope tomography (SIT) model version 1

    SciTech Connect

    Carroll, J.; Abraham, J.D.

    1996-03-08

    Geochronology using {sup 210}Pb is the principal method used to quantify sediment accumulation in rapidly depositing aquatic environments such as lakes, estuaries, continental shelves, and submarine canyons. This method is based on the radioactive decay of {sup 210}Pb with depth in a column of sediment. The decay through time of {sup 210}Pb P(t) is governed by the exponential law P(t) = P{sub 0} exp( -{lambda}t) where P{sub 0} is the surficial concentration at time t = 0, and {lambda} is the decay constant (3.114 {sm_bullet} 10{sup -2} year [yr]{sup -1} for {sup 210}Pb). If the sedimentation rate is constant, then elapsed time t is connected to burial depth x, through x = Vt where V is the sedimentation velocity. Accordingly, P(x) = P{sub 0}exp( -{lambda}x/V). The sedimentation velocity is obtained from an exponential fit to the measured {sup 210}Pb data P(x), with depth x.

  9. Phosphorus and nitrogen in coral reef sediments

    SciTech Connect

    Entsch, B.; Boto, K.G.; Sim, R.G.; Wellington, J.T.

    1983-05-01

    The occurrence of P and N in the sediments has been investigated on Davies Reef in the central region of the Great Barrier Reef Complex. Concentrations of inorganic P and N in the water were typical of nutrient-depleted tropical surface water. Carbonate sediments were found to contain a uniform pool of P (300 ppm by wt), principally in the form of inorganic phosphate. The interstitial water of the surface layer of sediment contained micromolar concentrations of inorganic P and even higher concentrations of inorganic N, principally as ammonium. These nutrient concentrations were considered too low to compete significantly with the uptake of available phasphate into algae. The presence of ammonium and soluble P was associated with anaerobic redox potentials in the sediments just below the surface. Soluble phosphorus was in equilibrium with a small, rapidly exchangeable fraction of the sedimentary pool of inorganic phosphate. Analyses of P in growing tips of Halimeda and corals (which supply more than half of reef sediments) suggested that the skeletons provide a biological mechanism for the replenishment of at least some of the sedimentary pool. Ratios of C:N:P for a selection of benthic algae were used as a preliminary indicator of thier N and P status.

  10. The transport of 'suspended' sediment by water

    NASA Astrophysics Data System (ADS)

    Parsons, Anthony; Cooper, James; Wainwright, John; Sekiguichi, Tomohiro

    2013-04-01

    Coherent turbulent flow structures, such as eddy-like, macro-turbulent structures and smaller scale bursting events, cause a two-way vertical exchange of momentum between the sediment bed and the water surface. Thus movement of suspended particles in open channel flows has a strong correlation with the advection and propagation of these turbulent flow structures, controlling entrainment , travel and deposition. Consequently, there is an argument in favour of the view that suspended sediment merely travels in suspension, but that its distance of travel is finite, and that between periods of travel it is at rest on the bed of the river. To test his hypothesis we added 25 kg of fluorescent sand, fine enough to be transported in suspension, into a steady flow discharge of 0.95 cumecs in the 160-m-long flume at Tsukuba University. After the flow event, a few grains of the sand were identified less than 5 m from the point of introduction and progressively (but irregularly) more downflume. Although our results are both limited and preliminary due to the nature of the existing flume, they clearly show that suspended sediment has a virtual velocity that is less than that of the flow in which the sediment is suspended. For the sediment-size range and flow velocity used in our experiment this virtual velocity is of the order of 50% of the water velocity.

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

    USGS Publications Warehouse

    Brim-Box, J.; Mossa, J.

    1999-01-01

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

  12. Mercury distribution in sediment profiles of six Louisiana Lakes.

    PubMed

    Gambrell, R P; DeLaune, R D; Patrick, W H; Jugsujinda, A

    2001-05-01

    A study was conducted of six Louisiana Lakes to examine the relationship between sediment properties including mercury content and health advisories associated with mercury levels in fish. Comparison was made between three lakes with health advisories (Black Lake, Chicot Lake, and Henderson Lake) and three lakes where the levels of mercury in fish are below health advisory levels (False River, Lake St. John, and Miller Lake). Three sediment core samples were collected from each lake and sectioned into 2-cm increments to a depth of 20 cm. Sediment properties measured in each depth increment of the sediment profile included total mercury, 137Cs activity (for sedimentation rate), and sediment organic matter content. Of the lakes studied, those lakes that have health advisories for mercury tended to have higher total mercury contents, usually higher sediment organic matter contents, and higher sedimentation rates than sediments in lakes where health advisories for mercury are not issued.

  13. Reach Scale Sediment Balance of Goodwin Creek Watershed, Mississippi

    NASA Astrophysics Data System (ADS)

    Ran, L.; Garcia, T.; Ye, S.; Harman, C. J.; Hassan, M. A.; Simon, A.

    2010-12-01

    Several reaches of Goodwin Creek, an experimental watershed within the Mississippi river basin, were analyzed for the period 1977-2007 in terms of long-term trends in sediment gain and loss in each reach, the relation of input and output to within-reach sediment fluxes, and the impacts of land use and bank erosion on reach sediment dynamics. Over the period 1977-2007, degradational and aggradational reaches were identified indicating slight vertical adjustment along the mainstream. Lateral adjustment was the main response of the channel to changes in flow and sediment regimes. Event-based sediment load was estimated using suspended concentration data, bedload transport rate, and changes in cross-sectional data. Bank erosion was estimated using cross-sectional data and models. The spatial and temporal patterns of within-reach sediment dynamics correspond closely with river morphology and also reflect basin conditions over the last three decades; thus they are conditioned by coeval trends in climate, hydrology, and land use. The sediment exchange within the mainstream was calculated by the development of reach sediment balances that reveal complex spatial and temporal patterns of sediment dynamics. Sediment load during the rising limb of the hydrograph was slightly higher than those estimated for the falling limb indicating the relative importance of sediment supply on reach sediment dynamic in the basin. Cumulative plots of sediment exchange reveal that major changes in within reach sediment storage are associated with large floods or major inputs from bank erosion.

  14. Mathematical simulation of sediment and radionuclide transport in estuaries

    SciTech Connect

    Onishi, Y.; Trent, D.S.

    1982-11-01

    The finite element model LFESCOT (Flow, Energy, Salinity, Sediment and Contaminant Transport Model) was synthesized under this study to simulate radionuclide transport in estuaries to obtain accurate radionuclide distributions which are affected by these factors: time variance, three-dimensional flow, temperature, salinity, and sediments. Because sediment transport and radionuclide adsorption/desorption depend strongly on sizes or types of sediments, FLESCOT simulates sediment and a sediment-sorbed radionuclide for the total of three sediment-size fractions (or sediment types) of both cohesive and noncohesive sediments. It also calculates changes of estuarine bed conditions, including bed elevation changes due to sediment erosion/deposition, and three-dimensional distributions of three bed sediment sizes and sediment-sorbed radionuclides within the bed. Although the model was synthesized for radionuclide transport, it is general enough to also handle other contaminants such as heavy metals, pesticides, or toxic chemicals. The model was checked for its capability for flow, water surface elevation change, salinity, sediment and radionuclide transport under various simple conditions first, confirming the general validity of the model's computational schemes. These tests also revealed that FLESCOT can use large aspect ratios of computational cells, which are necessary in handling long estuarine study areas. After these simple tests, FLESCOT was applied to the Hudson River estuary between Chelsea and the mouth of the river to examine how well the model can predict radionuclide transport through simulating tidally influenced three-dimensional flow, salinity, sediment and radionuclide movements with their interactions.

  15. Air emissions from exposed contaminated sediments and dredged material

    SciTech Connect

    Valsaraj, K.T.; Ravikrishna, R.; Reible, D.D.; Thibodeaux, L.J.; Choy, B.; Price, C.B.; Brannon, J.M.; Myers, T.E.; Yost, S.

    1999-01-01

    The sediment-to-air fluxes of two polycyclic aromatic hydrocarbons (phenanthrene and pyrene) and a heterocyclic aromatic hydrocarbon (dibenzofuran) from a laboratory-contaminated sediment and those of three polycyclic aromatic hydrocarbons (naphthalene, phenanthrene, and pyrene) from three field sediments were investigated in experimental microcosms. The flux was dependent on the sediment moisture content, air-filled porosity, and the relative humidity of the air flowing over the sediment surface. The mathematical model predictions of flux from the laboratory-spiked sediment agreed with observed values. The fluxes of compounds with higher hydrophobicity were more air-side resistance controlled. Conspicuous differences were observed between the fluxes from the laboratory-spiked and two of the three field sediments. Two field sediments showed dramatic increases in mass-transfer resistances with increasing exposure time and had significant fractions of oil and grease. The proposed mathematical model was inadequate for predicting the flux from the latter field sediments. Sediment reworking enhanced the fluxes from the field sediments due to exposure of fresh solids to the air. Variations in flux from the lab-spiked sediment as a result of change in air relative humidity were due to differences in retardation of chemicals on a dry or wet surface sediment. High moisture in the air over the dry sediment increased the competition for sorption sites between water and contaminant and increased the contaminant flux.

  16. Evolution of particle velocity correlations in sedimentation

    NASA Astrophysics Data System (ADS)

    Guazzelli, Elisabeth

    2000-11-01

    The problem of velocity fluctuations in sedimentation is still unresolved. The velocity fluctuations are observed experimentally to form into characteristic correlated regions [see Segre et al. (1997) and Bernard-Michel (2000)]. The origin of these correlations is still an open question. How correlation between particle velocities develops in a well mixed suspension? What is the ultimate structure of the sedimenting suspension? To tackle these questions, particle velocity fields are measured using particle image velocimetry. The sedimentation process is observed to be dominated by velocity fluctuation structures of the size of the container in the initial moments after the mixing, which diminish with time down to a size of the order of 20 interparticle spacings.

  17. Lipids of aquatic sediments, recent and ancient

    NASA Technical Reports Server (NTRS)

    Eglinton, G.; Hajibrahim, S. K.; Maxwell, J. R.; Quirke, J. M. E.; Shaw, G. J.; Volkman, J. K.; Wardroper, A. M. K.

    1979-01-01

    Computerized gas chromatography-mass spectrometry (GC-MS) is now an essential tool in the analysis of the complex mixtures of lipids (geolipids) encountered in aquatic sediments, both 'recent' (less than 1 million years old) and ancient. The application of MS, and particularly GC-MS, has been instrumental in the rapid development of organic geochemistry and environmental organic chemistry in recent years. The techniques used have resulted in the identification of numerous compounds of a variety of types in sediments. Most attention has been concentrated on molecules of limited size, mainly below 500 molecular mass, and of limited functionality, for examples, hydrocarbons, fatty acids and alcohols. Examples from recent studies (at Bristol) of contemporary, 'recent' and ancient sediments are presented and discussed.

  18. Toxicity of sediment-incorporated drilling fluids

    SciTech Connect

    Clark, J.R.; Patrick, J.M.

    1987-01-01

    The 24, 96, or 168-h LC50s of four used drilling fluids or barite incorporated into sediment were determined in toxicity tests with lancelets (Branchiostoma caribaeum), a benthic chordate. The number of lancelets that did not burrow into contaminated sediments was used to calculate EC50s at the same times that LC50s were determined. Observations of the burrowing behavior allowed quantitation of effects after 24-h exposures to each of the drilling fluids whereas lancelet mortality was sufficient to calculate 24-h LC50s for only one drilling fluid. Drilling fluids were less toxic to lancelets when incorporated into sediments than to mysids (Mysidopsis bahia) or benthic invertebrate communities in water-column exposures.

  19. Carotenoid diagenesis in a marine sediment

    NASA Technical Reports Server (NTRS)

    Watts, C. D.; Maxwell, J. R.

    1977-01-01

    The major carotenoids at three levels (3, 40, and 175 m below the sediment-water interface) in a core from a marine sediment (Cariaco Trench, off Venezuela) have been examined. Mass and electronic spectral data have provided evidence for the onset of a progressive reduction of carotenoids in the geological column. The time scale of the process appears to depend on the particular carotenoid. Reduction of up to two double bonds is observed for the diol, zeaxanthin, in the oldest sediment (about 340,000 years old) but no reduction is observed in the younger samples (about 5000 and 56,000 years old). The diketone, canthaxanthin, shows evidence of reduction of up to two double bonds in the 56,000-yr sample and up to five double bonds in the oldest sample. No reduction of beta-carotene was observed in any of the samples.

  20. Shear wave velocity measurements in marine sediments

    NASA Astrophysics Data System (ADS)

    Matthews, J. E.

    1982-09-01

    Pulsed ultrasonic techniques for the measurement of sound speed are reliable and well documented. Extension of these techniques to the measurement of shear wave velocities in marine sediments, generally was unsuccessful. Recently developed shear wave transducers, based upon piezoelectric benders operated at sonic frequencies, provide significantly improved transducer-sample mechanical coupling. This improved coupling allows the application of pulsed techniques to the measurement of shear wave velocities in marine sediments, and the rapid determination of sediment dynamic elastic properties. Two types of bender-based shear wave transducer and preliminary data are described: 1) a probe configuration for box core samples, and 2) a modification to the Hamilton Frame Velocimeter for cut samples.

  1. Marine clathrate mining and sediment separation

    DOEpatents

    Borns, David J.; Hinkebein, Thomas E.; Lynch, Richard W.; Northrop, David A.

    2001-01-01

    A method and apparatus for mining of hydrocarbons from a hydrocarbon-containing clathrate such as is found on the ocean floor. The hydrocarbon containing clathrate is disaggregated from sediment by first disrupting clathrate-containing strata using continuous mining means such as a rotary tilling drum, a fluid injector, or a drill. The clathrate-rich portion of sediment thus disrupted from the sea floor strata are carried through the apparatus to regions of relative lower pressure and/or relative higher temperature where the clathrate further dissociates into component hydrocarbons and water. The hydrocarbon is recovered with the assistance of a gas that is injected and buoys the hydrocarbon containing clathrate helping it to rise to regions of lower pressure and temperature where hydrocarbon is released. The sediment separated from the hydrocarbon returns to the ocean floor.

  2. History of the Federal Interagency Sedimentation Project

    USGS Publications Warehouse

    Skinner, John V.

    1989-01-01

    Since 1939, the date of the Project's inception, the team has operated under the direction of two lead agencies - the U.S. Geological Survey and U.S. Army Corps of Engineers. The supporting agencies are the Agricultural Research Service, Bureau of Reclamation, U.S. Forest Service, Bureau of Land Management, Federal Highway Administration, and the Tennessee Valley Authority. Overall direction of the Project rests with the Subcommittee on Sedimentation, Interagency Advisory Committee on Water Data. The Project's goals focus on improving and maintaining the quality of fluvial sediment data by (1) developing sediment samplers, laboratory analyzers, and automatic gages (2) evaluating methods, (3) standardizing equipment and methods and (4) procuring, calibrating and selling equipment.

  3. Meiofauna increases bacterial denitrification in marine sediments

    PubMed Central

    Bonaglia, S.; Nascimento, F. J. A; Bartoli, M.; Klawonn, I.; Brüchert, V.

    2014-01-01

    Denitrification is a critical process that can alleviate the effects of excessive nitrogen availability in aquatic ecosystems subject to eutrophication. An important part of denitrification occurs in benthic systems where bioturbation by meiofauna (invertebrates <1 mm) and its effect on element cycling are still not well understood. Here we study the quantitative impact of meiofauna populations of different abundance and diversity, in the presence and absence of macrofauna, on nitrate reduction, carbon mineralization and methane fluxes. In sediments with abundant and diverse meiofauna, denitrification is double that in sediments with low meiofauna, suggesting that meiofauna bioturbation has a stimulating effect on nitrifying and denitrifying bacteria. However, high meiofauna densities in the presence of bivalves do not stimulate denitrification, while dissimilatory nitrate reduction to ammonium rate and methane efflux are significantly enhanced. We demonstrate that the ecological interactions between meio-, macrofauna and bacteria are important in regulating nitrogen cycling in soft-sediment ecosystems. PMID:25318852

  4. Degradation of methyl bromide in anaerobic sediments

    USGS Publications Warehouse

    Oremland, R.S.; Miller, L.G.; Strohmaler, F.E.

    1994-01-01

    Methyl bromide (MeBr) was anaerobically degraded in saltmarsh sediments after reaction with sulfide. The product of this nucleophilic substitution reaction was methanethiol, which underwent further chemical and bacterial reactions to form dimethyl sulfide. These two gases appeared transiently during sediment incubations because they were metabolized by methanogenic and sulfate-reducing bacteria. A second, less significant reaction of MeBr was the exchange with chloride, forming methyl chloride, which was also susceptible to attack by sulfide. Incubation of 14C-labeled methyl iodide as an analogue of MeBr resulted in the formation of 14CH4 and 14CO2 and also indicated that sulfate-reducing bacteria as well as methanogens metabolized the methylated sulfur intermediates. These results suggest that exposed sediments with abundant free sulfide, such as coastal salt-marshes, may constitute a sink for atmospheric MeBr.

  5. Acyclic archaebacterial ether lipids in swamp sediments

    NASA Astrophysics Data System (ADS)

    Pauly, George G.; Van Vleet, Edward S.

    1986-06-01

    Acyclic phytanyl diether glycerol and biphytanyl ether lipids have been quantified in two modern swamp sediment cores in concentrations ranging up to 360 μg/ml porewater. Methanogenic bacteria are the only known source organisms which can inhabit the swamp sediments. Variations in relative abundance between these lipids may reflect taxonomic changes in methanogen populations or the stage of growth. Maxima in methanogen lipid concentrations coincide with local maxima of 13C of organic matter, possibly the result of a pool effect on CO 2 or acetate. Methane production estimates calculated from lipid concentrations in swamp sediments range from 0.1 to 1.3 mmol cm -2 yr -1, values which are consistent with published methane fluxes.

  6. Sediment thickness in the southern Canada Basin

    USGS Publications Warehouse

    May, S.D.; Grantz, A.

    1990-01-01

    Multichannel seismic reflection data are used, in conjunction with deep crustal seismic refraction data, to estimate the thickness of sediments in the southern Canada Basin of the Arctic Ocean north of Alaska. The sediments are interpreted to be of Hauterivian (mid-Early Cretaceous) to Holocene age. Comparison of the seismic reflection character of seismic reflections in the study area with that in other basins indicates that a base-of-sediment-top of oceanic layer 2 reflection is not present above the depth at which the water-bottom multiple obscures all deeper arrivals, which is in conflict with the conclusions drawn from aeromagnetic, refraction, and other reflection studies. Seismic velocity structure, determined from the reflection data, indicates that the reflections above the multiple are from sedimentary strata. In the absence of seismic reflection evidence for the top of layer 2 above the multiple, we estimate total sediment thickness by using the layer 3 refractions and subtracting an average assumed layer 2 thickness from the top of layer 3. Assuming that an average thickness of oceanic layer 2 (1.4 km) overlies layer 3 in the southern Canada Basin, sediment thickness in the study area is estimated to range between 6.5 km where water depth is 3.8 km to greater than 11 km where the water depth is 2 km. This is nearly double that of any previous estimates and should have a significant effect on calculations such as the age of Canada Basin, regional heat flow, and long-term sedimentation rates. ?? 1990.

  7. Metal and sediment ingestion by dabbling ducks

    USGS Publications Warehouse

    Beyer, W.N.; Spann, J.; Day, D.

    1999-01-01

    The chemical analysis of intestinal digesta from hunter-killed carcasses or of wildlife scat is a promising means of estimating the exposure of wildlife to those environmental contaminants that, like lead, are poorly absorbed in the digestive tract. When evaluating contaminants at a site, biologists may find the results of this non-destructive approach more straightforward to interpret in terms of exposure to wildlife than would be analyses of soils, sediments, water, or wildlife tissues. To illustrate the approach, we collected digesta from 47 waterfowl shot by hunters at Prime Hook National Wildlife Refuge, in Delaware, USA. The waterfowl digesta contained an average of approximately 2.4% sediment, estimated from the Al concentrations in the digesta, a marker for sediment. Al concentrations were significantly correlated with concentrations of Cr (Spearman's rank correlation coefficient, r=0.57), V (r=0.70), Ni (r=0.31), and Pb (r=0.55), and we concluded that these metals were ingested mainly with sediment. American widgeon (Anas americana) ingested sediment at a rate of about four times that of three other species of dabbling ducks (Anas crecca, A. acuta, A. rubripes) and had several times the exposure to the sediment-associated metals. The digesta of one American black duck contained a high concentration of lead (70 mg/kg, dry wt.), presumably from lead shot, but none of the other samples had notably elevated metal concentrations. We suggest that scat and digesta be analyzed more widely by biologists and resource managers seeking a simple, inexpensive assessment of contaminants in local wildlife habitat.

  8. Redistribution of intertidal sediment contaminants by microphytobenthos

    NASA Astrophysics Data System (ADS)

    Becker, Amani; Copplestone, David; Tyler, Andrew; Smith, Nick; Sneddon, Christopher

    2014-05-01

    Microphytobenthos (MPB) is a mixed community of microscopic algae inhabiting the top few millimetres of bottom sediment in the intertidal zone. It is a key component of the estuarine ecosystem, interacting with the sediment and fauna to influence sediment distribution and resuspension and forming the base of the estuarine food chain. Estuarine sediments, with which the MPB is closely associated, are a significant sink for contaminants from both fluvial and marine sources. Algae are known to have the capacity to take up contaminants, and the phytoplankton has been well studied in this respect, however there has been little research involving MPB. The extent to which contaminant uptake by MPB occurs and under what conditions is therefore very poorly understood. It seems probable that the paucity of research in this area is due to the complexity of the bioavailability of contaminants in the intertidal zone coupled with difficulties in separating MPB from the sediment. A series of experiments are proposed in which we will investigate (at a range of spatial scales) contaminant partitioning in the presence of MPB; the effect of changing temperatures on contaminant uptake and toxicity to MPB; effects of sediment resuspension on contaminant availability and uptake to MPB; and the uptake of contaminants from MPB to molluscs. A mesocosm (or experimental enclosure) is being constructed to replicate the natural system and enable manipulation of conditions of interest. This will attain greater realism than laboratory toxicity tests, with more statistical power than can be achieved through field studies. By gaining a better understanding of processes governing contaminant bioavailability and mechanisms for uptake by MPB it will be possible to relate these to projected climate change effects and ascertain potential consequences for contaminant redistribution.

  9. Sediment gravity flow—the conceptual problems

    NASA Astrophysics Data System (ADS)

    Dasgupta, Prabir

    2003-09-01

    The term sediment gravity flow was introduced to describe the major flow types involved in resedimentation processes and was defined as the flow of sediments or sediment-fluid mixture in which the interstitial fluid is driven by the grains moving under the action of gravity. Critical analysis of respective flow mechanism reveals that these flow types markedly depart from the definitive properties of a sediment gravity flow, and the possibility of natural existence of a sediment gravity flow sensu stricto appears doubtful. The flow types classified as sediment gravity flow are also different enough from each other to be considered under a single category based on flow mechanism, and a more general term, high-density flow, is proposed here as a rational alternative to designate them. Attempts made to classify these flows on the basis of rheologic properties also suffer from some serious limitations. Besides these basic problems, improper uses of different terminology cause problems in understanding these high-density flows. Critical review, however, leads to conclude that each of these flow types can be identified as a distinct segment of a continuous spectrum of high-density flows, and the process of transformation from one variety to the other often comes into existence. Even within a single flow, different parts may show distinct flow character developed through the process of flow transformation. An empirical relationship between these flow types thus can be established with reference to the grain/water ratio and grain composition, which broadly controls character and rheology of a specific variety or different parts of a composite flow. An attempt is made here to accommodate the high-density flows involved in resedimentation processes within a general classification of aqueous flows.

  10. Heavy metal removal from sediments by biosurfactants.

    PubMed

    Mulligan, C N; Yong, R N; Gibbs, B F

    2001-07-30

    Batch washing experiments were used to evaluate the feasibility of using biosurfactants for the removal of heavy metals from sediments. Surfactin from Bacillus subtilis, rhamnolipids from Pseudomonas aeruginosa and sophorolipid from Torulopsis bombicola were evaluated using a metal-contaminated sediment (110mg/kg copper and 3300mg/kg zinc). A single washing with 0.5% rhamnolipid removed 65% of the copper and 18% of the zinc, whereas 4% sophorolipid removed 25% of the copper and 60% of the zinc. Surfactin was less effective, removing 15% of the copper and 6% of the zinc. The technique of ultrafiltration and zeta potential measurements were used to determine the mechanism of metal removal by the surfactants. It was then postulated that metal removal by the biosurfactants occurs through sorption of the surfactant on to the soil surface and complexation with the metal, detachment of the metal from the soil into the soil solution and hence association with surfactant micelles. Sequential extraction procedures were used on the sediment to determine the speciation of the heavy metals before and after surfactant washing. The carbonate and oxide fractions accounted for over 90% of the zinc present in the sediments. The organic fraction constituted over 70% of the copper. Sequential extraction of the sediments after washing with the various surfactants indicated that the biosurfactants, rhamnolipid and surfactin could remove the organically-bound copper and that the sophorolipid could remove the carbonate and oxide-bound zinc. Therefore, heavy metal removal from sediments is feasible and further research will be conducted.

  11. Amylose-iodine complex. I. Sedimentation behavior.

    PubMed

    Dintzis, F R; Beckwith, A C; Babcock, G E; Tobin, R

    1976-01-01

    Sedimentation measurements are reported on solutions of blue amylose-iodine complexes in the range of 0.001 to 0.007% amylose. Amylose fractions B and F2, of weight average molecular weight average molecular weight 4.0 X 10(5) and 3.4 X 10(4), respectively, were used in this study. Iodine complexes of these fractions formed polydisperse solutions of limited solubility and stability. Sedimentation coefficients increased as a function of potassium iodide concentration. Values for fraction B complexes varied from (16.3 +/- 1.0) X 10(-13) at 1.2 X 10(-3) M KI to (57.2 +/- 7.5) X 10(-13) at 8.3 X 10(-3) M KI; values for fraction F2 complexes varied from (10.0 +/- 1.2) X 10(-13) at 1.2 X 10(-13) M KI to (24.8 +/- 3.9) X 10(-13) at 9.5 X 10(-3) M KI. At constant potassium iodide concentration, sedimentation coefficients, within our experimental error of 10 to 15% standard deviation, are independent of amylose concentration. Time dependence of sedimentation coefficient values was observed for solutions either saturated or unsaturated with respect to the iodine-binding capacity of amylose. For iodine-saturated complex solutions, sedimentation coefficients extrapolated to zero potassium iodide concentration were two to three times greater than for the parent amylose. Measurements are evaluated in terms of possible polyelectrolytic charge effects and aggregation. Under conditions used in these experiments, aggregation of amylose-iodide complexes appears to be the mechanism responsible for the large increase in sedimentation coefficients.

  12. Meiofauna Metabolism in Suboxic Sediments: Currently Overestimated

    PubMed Central

    Braeckman, Ulrike; Vanaverbeke, Jan; Vincx, Magda; van Oevelen, Dick; Soetaert, Karline

    2013-01-01

    Oxygen is recognized as a structuring factor of metazoan communities in marine sediments. The importance of oxygen as a controlling factor on meiofauna (32 µm-1 mm in size) respiration rates is however less clear. Typically, respiration rates are measured under oxic conditions, after which these rates are used in food web studies to quantify the role of meiofauna in sediment carbon turnover. Sediment oxygen concentration ([O2]) is generally far from saturated, implying that (1) current estimates of the role of meiofauna in carbon cycling may be biased and (2) meiofaunal organisms need strategies to survive in oxygen-stressed environments. Two main survival strategies are often hypothesized: 1) frequent migration to oxic layers and 2) morphological adaptation. To evaluate these hypotheses, we (1) used a model of oxygen turnover in the meiofauna body as a function of ambient [O2], and (2) performed respiration measurements at a range of [O2] conditions. The oxygen turnover model predicts a tight coupling between ambient [O2] and meiofauna body [O2] with oxygen within the body being consumed in seconds. This fast turnover favors long and slender organisms in sediments with low ambient [O2] but even then frequent migration between suboxic and oxic layers is for most organisms not a viable strategy to alleviate oxygen limitation. Respiration rates of all measured meiofauna organisms slowed down in response to decreasing ambient [O2], with Nematoda displaying the highest metabolic sensitivity for declining [O2] followed by Foraminifera and juvenile Gastropoda. Ostracoda showed a behavioral stress response when ambient [O2] reached a critical level. Reduced respiration at low ambient [O2] implies that meiofauna in natural, i.e. suboxic, sediments must have a lower metabolism than inferred from earlier respiration rates conducted under oxic conditions. The implications of these findings are discussed for the contribution of meiofauna to carbon cycling in marine sediments

  13. Sediment yield as a desertification risk indicator.

    PubMed

    Vanmaercke, M; Poesen, J; Maetens, W; de Vente, J; Verstraeten, G

    2011-04-01

    Soil erosion is often regarded as one of the main processes of desertification. This has led to the use of various desertification indicators that are related to soil erosion. Most of these indicators focus, however, on small spatial units, while little attention has been given to the amount of sediment exported at the catchment scale. Such a small spatial unit approach neglects the transfer of sediment through catchments as well as the scale-dependency of erosion processes. Furthermore, this approach does not consider important off-site impacts of soil erosion, such as sediment deposition in reservoirs, flooding as well as ecological impacts. This study aims to illustrate the importance of also considering catchment sediment yield (SY, t km(-2) y(-1)) in desertification assessment studies. Based on recently established databases of SY and soil loss rates in Europe and examples from previous studies, we illustrate that soil erosion rates at the plot scale are not representative for catchment SY, as they are often several orders of magnitude smaller. Also, the erosion response of catchments to changes in land use or climate often differs strongly from responses to those changes at the plot scale. We further discuss several of the impacts of SY and their link with desertification: i.e. the sedimentation of reservoirs, problems related to flooding, catchment hydrology, export of nutrients and ecological implications. Using earlier established criteria we evaluate the potential for using catchment SY as a desertification indicator and conclude that this could give an important added value to desertification studies. SY, used in combination with other indicators, allows the identification of other sediment sources than those considered at the plot scale and can reflect the results of desertification processes over longer time periods than periods over which assessments at the plot scale have been made. We argue therefore, that SY is a strong complementary indicator of

  14. Sediment sources and their contribution along northern coast of the South China Sea: Evidence from clay minerals of surface sediments

    NASA Astrophysics Data System (ADS)

    Liu, Jianguo; Yan, Wen; Chen, Zhong; Lu, Jun

    2012-09-01

    Clay minerals of surface sediment samples from nine bays/harbors along northern coast of the South China Sea (SCS) are used for sediment sources and contribution estimation in the study areas. Results reveal that sediments in the study bays/harbors seem to be a mixture of sediments from the Pearl, Hanjiang River and local islands/rivers, but their clay mineral assemblage is distinct from that of Luzon and Taiwan sediments, indicating that sediments are derived mainly from the neighboring sources through riverine input and partly from localized sediments. Due to input of local sediments in the northern SCS, sediments from both east of the Leizhou Peninsula (Area IV) and next to the Pearl River estuary (PRE, Area II) have high smectite percent. Affected by riverine input of the Pearl and Hanjiang Rivers, sediments in west of the PRE (Area III) and east of the PRE (Area I) have high illite (average 47%) and kaolinite (54%) percents, respectively. Sediment contributions of various major sources to the study areas are estimated as the following: (1) the Hanjiang River provide 95% and 84% sediments in Areas I and II, respectively, (2) the Pearl River supply 79% and 29% sediments in Areas III and IV, respectively and (3) local sediments contribute the rest and reach the maximum (˜71%) in Area IV.

  15. Estimated post-Messinian sediment supply and sedimentation rates on the Ebro continental margin, Spain

    USGS Publications Warehouse

    Nelson, C.H.

    1990-01-01

    Because of the extensive data base of seismic profiles, radiometric ages, and stratigraphic time markers such as the subaerial Messinian surface, sedimentation rates and Ebro River sediment discharge can be estimated for different periods and environments of the Ebro continental margin. New values for sediment discharge (i.e., 6.2 versus previous estimates of 2-3.5 million t/yr) for the Holocene highstand are more reliable but remain minimum estimates because a small proportion of Ebro sediment advected to the Balearic Rise and Abyssal Plain cannot be accounted for, especially during lowstands. The general highstand conditions of the Pliocene, which were similar to those of the Holocene, resulted in a low discharge of Ebro River sediment (ca. 6.5 million t/yr) and an even thickness of sediment across the margin that deposited at rates of about 24-40 cm/ky. In contrast, sediment supply increased two-three times during the Pleistocene, the margin prograded rapidly and deposition occurred at rates of 101-165 cm/ky on the outer shelf and slope, but basin floor rates remained anomalously low (21-26 cm/ky) because sediment was drained and broadly dispersed eastward in Valencia Trough. During the late Pleistocene rise of sea level, the main depocenters progressively shifted shoreward and sedimentation rates greatly decreased from 175 cm/ky on the upper slope during the early transgression to 106 cm/ky on the outer shelf and then to 63 cm/ky on the mid-shelf during the late transgression as the river sediment discharge dropped to half by Holocene time. Maximal sedimentation rates occurred in active depocenters of sediment dispersal such as the Holocene delta (370 cm/ky) or the youngest Pleistocene Oropesa channel-levee complex (705 cm/ky) where deposition rates increased by an order of magnitude or more compared to average Ebro shelf (38 cm/ky) or base-of-slope rates in the Pleistocene (21 cm/ky). The sedimentation rates verify the importance of sea-level control on the

  16. Assessment of heavy metals contamination in Mamut river sediments using sediment quality guidelines and geochemical indices.

    PubMed

    Mohammad Ali, Bibi Noorarlijannah; Lin, Chin Yik; Cleophas, Fera; Abdullah, Mohd Harun; Musta, Baba

    2015-01-01

    This paper describes the concentration of selected heavy metals (Co, Cu, Ni, Pb, and Zn) in the Mamut river sediments and evaluate the degree of contamination of the river polluted by a disused copper mine. Based on the analytical results, copper showed the highest concentration in most of the river samples. A comparison with Interim Canadian Sediment Quality Guidelines (ICSQG) and Germany Sediment Quality Guidelines (GSQG) indicated that the sediment samples in all the sampling stations, except Mamut river control site (M1), exceeded the limit established for Cu, Ni, and Pb. On the contrary, Zn concentrations were reported well below the guidelines limit (ICSQG and GSQG). Mineralogical analysis indicated that the Mamut river sediments were primarily composed of quartz and accessory minerals such as chalcopyrite, pyrite, edenite, kaolinite, mica, and muscovite, reflected by the geological character of the study area. Enrichment factor (EF) and geoaccumulation index (Igeo) were calculated to evaluate the heavy metal pollution in river sediments. Igeo values indicated that all the sites were strongly polluted with the studied metals in most sampling stations, specifically those located along the Mamut main stream. The enrichment factor with value greater than 1.5 suggested that the source of heavy metals was mainly derived from anthropogenic activity such as mining. The degree of metal changes (δfold) revealed that Cu concentration in the river sediments has increased as much as 20 to 38 folds since the preliminary investigation conducted in year 2004.

  17. Modeling methane bubble growth in fine-grained muddy aquatic sediments: correlation with sediment properties

    NASA Astrophysics Data System (ADS)

    Katsman, Regina

    2015-04-01

    Gassy sediments contribute to destabilization of aquatic infrastructure, air pollution, and global warming. In the current study a precise shape and size of the buoyant mature methane bubble in fine-grained muddy aquatic sediment is defined by numerical and analytical modeling, their results are in a good agreement. A closed-form analytical solution defining the bubble parameters is developed. It is found that the buoyant mature bubble is elliptical in its front view and resembles an inverted tear drop in its cross-section. The size and shape of the mature bubble strongly correlate with sediment fracture toughness. Bubbles formed in the weaker sediments are smaller and characterized by a larger surface-to volume ratio that induces their faster growth and may lead to their faster dissolution below the sediment-water interface. This may prevent their release to the water column and to the atmosphere. Shapes of the bubbles in the weaker sediments deviate further from the spherical configuration, than those in the stronger sediments. Modeled bubble characteristics, important for the acoustic applications, are in a good agreement with field observations and lab experiments.

  18. Sediment studies at Bikini Atoll part 2. inventories of transuranium elements in surface sediments

    SciTech Connect

    Noshkin, V.E.; Eagle, R.J.; Wong, K.M.; Robison, W.L.

    1997-10-01

    This is the second of three reports on Bikini sediment studies, which discusses the concentrations and inventories of {sup 241}Am and {sup 239+240}Pu in sediments from the lagoon. Surface sediment samples were collected from 87 locations over the entire lagoon at Bikini Atoll during 1979. The collections were made to map the distribution of long-lived radionuclides associated with the bottom material and to show what modifications occurred in the composition of the sediment as a result of the testing program. Present inventories for {sup 241}Am and {sup 239+240}Pu in the surface 2 cm of sediment are estimated to be 14 and 17 TBq, respectively. These values are estimated to represent only 14% of the total inventory in the sediment column. Sediment inventories of {sup 239+240}Pu and {sup 241}Am are changing only slowly with time through chemical- physical processes that continuously mobilize small amounts of the transuranics to the water column. The lowest concentrations and inventories are associated with deposits logoonward of the eastern reef.

  19. Avoidance response of sediment living amphipods to zinc pyrithione as a measure of sediment toxicity.

    PubMed

    Eriksson Wiklund, Ann-Kristin; Börjesson, Therese; Wiklund, Stig Johan

    2006-01-01

    An avoidance test was developed using non-cultured individuals of the sediment dwelling amphipod Monoporeia affinis. As test substance we used zinc pyrithione, an antifouling agent and a common shampoo ingredient. The toxicity to Daphnia and fish is well known but sediment toxicity of this very hydrophobic compound is less known. The preference of juvenile M. affinis was tested in jars, each including 12 petri dishes. In each replicate, half of the petri dishes contained sediment mixed with six concentrations ranging from 0 to 10microg zinc pyrithione per L sediment and half of the petri dishes contained the corresponding sediment-substance mixture plus an extra food addition. The amphipods significantly avoided petri dishes with the three highest concentrations of zinc pyrithione and the calculated EC(50) was 9.65microgL(-1) sediment. No difference in mortality was observed between concentrations. Using the avoidance behaviour in sediment toxicity testing is a simple and cost-effective screening for toxicants.

  20. Evaluation of sediment yield and sediment data-collection network in the Piceance basin, northwestern Colorado

    USGS Publications Warehouse

    Kircher, J.E.; Von Guerard, Paul

    1982-01-01

    Statistical relationships were developed between suspended-sediment discharge and several regional factors of climate, physiography, and land use in the Piceance basin, northwestern Colorado. The purpose of the study was to evaluate the existing sediment collection network, especially in regard to detecting changes in suspended-sediment discharge due to the development in the basin. Spatial- and time variability were examined using multiple linear regression techniques. Because of the short period of record, monthly mean sediment loads were used to determine shifts or changes in trends due to mining and related activities in the basin. Dummy variable analysis was used to detect these premining and postmining differences in the regression lines and also to detect seasonal differences in the sediment discharge. Differences did exist in the sediment discharge from season to season and before and after mining; however, due to the variability and short period of record the cause of these differences could not be adequately determined. Part of the high variability in sediment discharge was due to variability in the water discharge. Therefore, if the network is to be improved, the emphasis needs to be on improvement of the water-discharge. The results of the monthly mean regression analysis were used in the mean monthly and mean annual analysis for determination of initial network design equations. These were only preliminary in nature and could be improved with additional data. (USGS)

  1. Marine sediments in Disko Trough reveal meltwater-influenced sedimentation during ice-stream retreat

    NASA Astrophysics Data System (ADS)

    Hogan, Kelly A.; Cofaigh, Colm Ó.; Jennings, Anne E.; Dowdeswell, Julian A.

    2015-04-01

    Marine geophysical data from middle and outer Disko Trough, West Greenland reveal thick (more than ten metres) acoustically-laminated, fine-grained sediments between subglacial tills at their base and post-glacial marine sediments at the seafloor. These sediments are interpreted as a transitional facies deposited as ice retreated from the trough during deglaciation. New sediment-core records indicate that these units were likely deposited by meltwater plumes emanating from a nearby grounded-ice margin, probably during stillstands in ice retreat. The retreat of ice in the trough may have been stabilised at a narrowing in DiskoTrough on the mid-shelf, as well as at the basalt escarpment south of Disko Island. Such thicknesses of deglacial or "transitional" glacimarine sediments are relatively unusual on high-latitude continental shelves and indicate a significant meltwater production in central West Greenland during deglaciation. This is consistent with the seafloor landforms in the inner and middle parts of the trough that include channels and moats around bedrock protrusions that look to have been eroded by water. IRD counts from the cores indicate that iceberg rafting also occurred during this transitional phase but that this signal was diluted by the fine-grained transitional sediments. Once ice had withdrawn from the area and sedimentation was hemipelagic in nature the IRD signal was less diluted.

  2. Notes on sedimentation activities calendar year 1988

    USGS Publications Warehouse

    ,

    1989-01-01

    This report is a digest of information furnished by Federal agencies conducting sedimentation investigations. The decision to publish the report was made in 1946, from a proposal by the Chairman of the Federal Interagency River Basin Committee, Subcommittee on Ground Water. The subcommittee approved the proposal and agreed to issue this report as a means of effecting better coordination of the work of various Federal agencies in the field of sedimentation. The report was issued on a quarterly basis in 1946 and 1947, from 1948 to 1953 reports were issued every 6 months, and from 1954 to the present, the report has been issued annually.

  3. Notes on sedimentation activities calendar year 1984

    USGS Publications Warehouse

    ,

    1985-01-01

    This report is a digest of information furnished by Federal agencies conducting sedimentation investigations. The decision to publish the report was made in 1946, from a proposal by the Chairman of the Federal Interagency River Basin Committee, Subcommittee on Ground Water. The Subcommittee approved the proposal and agreed to issue this report as a means of effecting better coordination of the work of various Federal agencies in the field of sedimentation. From 1946 to 1947 the report was issued on a quarterly basis, from 1948 to 1953 reports were issued every 6 months, and from 1954 to the present the report has been issued annually.

  4. Notes on sedimentation activities calendar year 1989

    USGS Publications Warehouse

    ,

    1990-01-01

    This report is a digest of information furnished by Federal agencies conducting sedimentation investigations. The decision to publish the report was made in 1946, from a proposal by the Chairman of the Federal Interagency River Basin Committee, Subcommittee on Ground Water. The subcommittee approved the proposal and agreed to issue this report as a means of effecting better coordination of the work of various Federal agencies in the field of sedimentation. The report was issued on a quarterly basis in 1946 and 1947, from 1948 to 1953 reports were issued every 6 months, and from 1954 to the present, the report has been issued annually.

  5. Notes on sedimentation activities calendar year 1985

    USGS Publications Warehouse

    ,

    1986-01-01

    This report is a digest of information furnished by Federal agencies conducting sedimentation investigations. The decision to publish the report was made in 1946, from a proposal by the Chairman of the Federal Interagercy River Basin Committee, Subcommittee on Ground Water. The subcommittee approved the proposal and agreed to issue this report as a means of effecting better coordination of the work of various Federal agencies in the field of sedimentation. From 1946 to 1947, the report was issued on a quarterly basis; from 1948 to 1953, reports were issued every 6 months; and from 1954 to the present, the report has been issued annually.

  6. Notes on sedimentation activities calendar year 1987

    USGS Publications Warehouse

    ,

    1988-01-01

    This report is a digest of information furnished by Federal agencies conducting sedimentation investigations. The decision to publish the report was made in 1946, from a proposal by the Chairman of the Federal Interagency River Basin Committee, Subcommittee on Ground Water. The subcommittee approved the proposal and agreed to issue this report as a means of effecting better coordination of the work of various Federal agencies in the field of sedimentation. The report was issued on a quarterly basis in 1946 and 1947, from 1948 to 1953 reports were issued every 6 months, and from 1954 to the present, the report has been issued annually.

  7. Anthropopression markers in lake bottom sediments

    NASA Astrophysics Data System (ADS)

    Nadolna, Anna; Nowicka, Barbara

    2014-05-01

    Lakes are vulnerable to various types of anthropogenic disturbances. Responses of lake ecosystems to environmental stressors are varied and depend not only on the type of a factor but also on the lake natural resistance to degradation. Within the EULAKES project an evaluation of anthropogenic stress extent in a flow-through, postglacial, ribbon lake (Lake Charzykowskie) was carried out. It was assumed, that this impact manifests unevenly, depending on a type and degree of the pressure on the shore zones, water quality of tributaries, lake basin shape and dynamics of a water movement. It was stated, that anthropogenic markers are substances accumulated in bottom sediments as a result of allochthonous substances inflow from the catchment and atmosphere. Along the selected transects 105 samples from the top layer of sediments (about 20 cm) was collected representing the contemporary accumulation (about 15 years). The content of selected chemical elements and compounds was examined, including nutrients (TN and TP), heavy metals (arsenic, cadmium, lead, chromium, nickel, copper, zinc, mercury, iron, and manganese) and pesticides (DDT, DDD, DDE, DMDT , γ-HCH). The research was conducted in the deepest points of each lake basin and along the research transects - while choosing the spots, the increased intensity of anthropogenic impact (ports, roads with heavy traffic, wastewater discharge zones, built-up areas) was taken into consideration. The river outlets to the lake, where there are ecotonal zones between limnic and fluvial environment, were also taken into account. Analysis of the markers distribution was carried out against the diversity of chemical characteristics of limnic sediments. Ribbon shape of the lake basin and the dominant wind direction provide an opportunity of easy water mixing to a considerable depth. Intensive waving processes cause removal of the matter from the littoral zone towards lake hollows (separated by the underwater tresholds), where the

  8. A new river sediment standard reference material.

    PubMed

    Epstein, M S; Diamondstone, B I; Gills, T E

    1989-01-01

    The collection, processing and certification of a new sediment Standard Reference Material (SRM), SRM 2704, is described. Collected from the bottom of the Buffalo River in New York State during the fall of 1986, SRM 2704 is certified for 25 elements with information provided on another 22 elements. Improvements in analytical methods as well as the application of well-defined quality-control procedures for collection, processing and analysis have resulted in a reference material that is more completely characterized than previous NIST sediment reference materials.

  9. Sediments at the top of Earth's core.

    PubMed

    Buffett, B A; Garnero, E J; Jeanloz, R

    2000-11-17

    Unusual physical properties at the core-mantle boundary have been inferred from seismic and geodetic observations in recent years. We show how both types of observations can be explained by a layer of silicate sediments, which accumulate at the top of the core as Earth cools. Compaction of the sediments expels most of the liquid iron but leaves behind a small amount of core material, which is entrained in mantle convection and may account for the isotopic signatures of core material in some hot spot plumes. Extraction of light elements from the liquid core also enhances the vigor of convection in the core and may increase the power available to the geodynamo.

  10. Gas Bubble Growth in Muddy Sediments

    DTIC Science & Technology

    2016-06-07

    it is fairly easy to show that R ~ eat (a = S/ρg), i.e. exponential growth , which is a far faster than has been suggested previously. We expect this...Gas Bubble Growth in Muddy Sediments Bernard P. Boudreau Department of Oceanography Dalhousie University Halifax, Nova Scotia B3H 4J1, Canada phone...objective is a working model for the growth of a single, isolated bubble in a marine sediment, validated with bubble growth data obtained in laboratory

  11. 300 Area process trench sediment analysis report

    SciTech Connect

    Zimmerman, M.G.; Kossik, C.D.

    1987-12-01

    This report describes the results of a sampling program for the sediments underlying the Process Trenches serving the 300 Area on the Hanford reservation. These Process Trenches were the subject of a Closure Plan submitted to the Washington State Department of Ecology and to the US Environmental Protection Agency in lieu of a Part B permit application on November 8, 1985. The closure plan described a proposed sampling plan for the underlying sediments and potential remedial actions to be determined by the sample analyses results. The results and proposed remedial action plan are presented and discussed in this report. 50 refs., 6 figs., 8 tabs.

  12. Examining Sediment-bound Radiocesium Dynamics in Two Fukushima Coastal Catchments with Sediment Fingerprinting Techniques

    NASA Astrophysics Data System (ADS)

    Laceby, J. P.; Lepage, H.; Bonté, P.; Joron, J. L.; Onda, Y.; Lefèvre, I.; Ayrault, S.; Evrard, O.

    2015-12-01

    The Fukushima Dai-ichi nuclear power plant accident resulted in the significant fallout of radiocesium (137Cs and 134Cs) over the Fukushima region. After deposition on the soil surface, radiocesium is primarily bound to fine soil particles. Subsequently, rainfall and snow melt run-off events result in the downstream migration of radiocesium. Understanding the spatial distribution and relative contribution of different sediment sources is therefore fundamental to the management of radiocesium migration. Sediment fingerprinting techniques were used to determine the location and relative contributions of different sediment sources in the Mano and Niida Rivers, in the Fukushima region. First, we modelled the relative contributions of radiocesium from the upstream portions of the catchment, that received greater proportions of the fallout (e.g. >20 kBq kg-1), to sediment sampled in the downstream coastal regions. Second, we examined the elemental geochemistry of the major soil types (e.g. Andosols, Cambisols, Fluvisols) within these catchments and modelled their relative contribution to sediment sampled throughout these catchments. Elemental composition was measured with neutron activation analysis, radiocesium with gamma-spectrometry and a distribution modelling approach quantified source contributions. In the Mano River ~20% of the radiocesium sampled was modelled to be derived from the upstream area compared to ~50% in the Niida River. The highest contribution of upstream radiocesium was modelled after the typhoon seasons in 2011 and 2013. Fluvisols were found to be the dominant source of sediment (76%). The dominance of Fluvisols indicates that sediments are likely derived from sources that are highly connected to the river network (e.g. rice paddy fields). Understanding the relative contributions of these different sediment sources will allow for more direct management of sediment and thus radiocesium transfers in these Fukushima coastal catchments.

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

    PubMed

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

    2007-01-01

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

  14. Hill-slope instability and sediment delivery: discerning geomorphological intensity from a lake sediment sequence.

    NASA Astrophysics Data System (ADS)

    Chiverrell, R. C.; Shen, Zhixiong; Bloemendal, J.

    2009-04-01

    An extensive database of radiocarbon dated alluvial fan and hill-slope gully systems identifies three phases of extensive hill-slope gullying after 2200, between 1250 and 700, and after 500 cal. BP in the uplands of northwest England. Regional pollen records reveal co-incident phases of increased human activity in these uplands, with small scale temporary clearances during the late Bronze Age / early Iron Age and more substantial clearances during the late Iron Age and Romano-British times (2300-1500 cal. BP), and later more substantial woodland clearances from c.1200-900 cal. BP, after which there has been little woodland recovery. This temporal pattern is similar to that in the geomorphology, and suggests that human activity is a critical factor mediating the late Holocene geomorphological record. To assess the linkages between geomorphic activity and adjacent lake basins a record of sediment delivery from a catchment to lake basin is provided by two c. 5.8 m long sediment cores from Crummock Water (NW England). A robust chronology for the sediment record is provided by parallel optical and 14C ages. The lake sediment magnetic and geochemical properties indicate a series of changes in sediment composition during the late Holocene, which correlate well with sediment lithology, water content and weight-loss-on-ignition. A comprehensive grid-based approach characterising the surface soil/sediment magnetic and geochemical properties has enabled a better understanding of source-sink linkages. In the upper 3-2 metres a suite of changes corresponds to the regional onset of human activity after 2000 BC, and particularly to the intensification of human activity at around AD 900. A comparison of the lake sediment magnetic properties and those of the catchment soils shows clear linkages for the period after AD 900. In contrast, detailed magnetic measurements of the early- through mid-Holocene sediments suggest that their magnetic properties are dominated by bacterial

  15. Toxicity of silicon carbide nanowires to sediment-dwelling invertebrates in water or sediment exposures

    USGS Publications Warehouse

    Mwangi, Joseph N.; Wang, Ning; Ritts, Andrew; Kunz, James L.; Ingersoll, Christopher G.; Li, Hao; Deng, Baolin

    2011-01-01

    Silicon carbide nanowires (SiCNW) are insoluble in water. When released into an aquatic environment, SiCNW would likely accumulate in sediment. The objective of this study was to assess the toxicity of SiCNW to four freshwater sediment-dwelling organisms: amphipods (Hyalella azteca), midges (Chironomus dilutus), oligochaetes (Lumbriculus variegatus), and mussels (Lampsilis siliquoidea). Amphipods were exposed to either sonicated or nonsonicated SiCNW in water (1.0 g/L) for 48 h. Midges, mussels, and oligochaetes were exposed only to sonicated SiCNW in water for 96 h. In addition, amphipods were exposed to sonicated SiCNW in whole sediment for 10 d (44% SiCNW on dry wt basis). Mean 48-h survival of amphipods exposed to nonsonicated SiCNW in water was not significantly different from the control, whereas mean survival of amphipods exposed to sonicated SiCNW in two 48-h exposures (0 or 15% survival) was significantly different from the control (90 or 98% survival). In contrast, no effect of sonicated SiCNW was observed on survival of midges, mussels, or oligochaetes. Survival of amphipods was not significantly reduced in 10-d exposures to sonicated SiCNW either mixed in the sediment or layered on the sediment surface. However, significant reduction in amphipod biomass was observed with the SiCNW either mixed in sediment or layered on the sediment surface, and the reduction was more pronounced for SiCNW layered on the sediment. These results indicated that, under the experimental conditions, nonsonicated SiCNW in water were not acutely toxic to amphipods, sonicated SiCNW in water were acutely toxic to the amphipods, but not to other organisms tested, and sonicated SiCNW in sediment affected the growth but not the survival of amphipods.

  16. Colorado River sediment transport 1. Natural sediment supply limitation and the influence of Glen Canyon Dam

    USGS Publications Warehouse

    Topping, D.J.; Rubin, D.M.; Vierra, L.E.

    2000-01-01

    Analyses of flow, sediment-transport, bed-topographic, and sedimentologic data suggest that before the closure of Glen Canyon Dam in 1963, the Colorado River in Marble and Grand Canyons was annually supply-limited with respect to fine sediment (i.e., sand and finer material). Furthermore, these analyses suggest that the predam river in Glen Canyon was not supply-limited to the same degree and that the degree of annual supply limitation increased near the head of Marble Canyon. The predam Colorado River in Grand Canyon displays evidence of four effects of supply limitation: (1) seasonal hysteresis in sediment concentration, (2) seasonal hysteresis in sediment grain size coupled to the seasonal hysteresis in sediment concentration, (3) production of inversely graded flood deposits, and (4) development or modification of a lag between the time of a flood peak and the time of either maximum or minimum (depending on reach geometry) bed elevation. Analyses of sediment budgets provide additional support for the interpretation that the predam river was annually supply-limited with respect to fine sediment, but it was not supply-limited with respect to fine sediment during all seasons. In the average predam year, sand would accumulate and be stored in Marble Canyon and upper Grand Canyon for 9 months of the year (from July through March) when flows were dominantly below 200-300 m3/s; this stored sand was then eroded during April through June when flows were typically higher. After closure of Glen Canyon Dam, because of the large magnitudes of the uncertainties in the sediment budget, no season of substantial sand accumulation is evident. Because most flows in the postdam river exceed 200-300 m3/s, substantial sand accumulation in the postdam river is unlikely.

  17. Sediment dispersal pattern in the Bay of Bengal - evidence for commencement of Bengal Fan sedimentation

    NASA Astrophysics Data System (ADS)

    Krishna, K. S.; Ismaiel, M.; Karlapati, S.; Gopala Rao, D.; Mishra, J.; D, S.

    2015-12-01

    The sediment succession in the Bay of Bengal records signatures corresponding to India-Asia collision, regional climate, and erosional processes of the Himalayan orogeny and the Indian subcontinent. The Bengal Fan - world's largest submarine fan - has been long studied to understand the link between the Himalayan tectonics and Asian monsoon climate, but early phase information of the Himalaya erosion is not retrieved from the Indian Ocean due to lack of deep-core samples. Therefore, the missing corresponding signals hampered the understanding of coupled processes between tectonics, climate and erosion. Seismic reflection profiles and industrial drill wells from the western Bay of Bengal show two different modes of sediment deposition: initially Indian peninsular rivers discharged sediments to the ocean at a rate ~20 m/m.y. until Oligocene-Miocene time (~23 Ma) with the exception of two fairly-enhanced sediment pulses from 65 to 54 and again from 34 to 23 Ma; since 23 Ma the Ganges and Brahmaputra rivers added huge volumes of sediments to the bay with variable rates range from 40 to >1000 m/m.y. Using seismic stratigraphic technique we found a distinct increase in sediment discharge (~140 m/m.y.) at 23 Ma is an important age marker for the onset of Bengal Fan sedimentation as a coupled connection between the Himalayan tectonics and Asian climate. Further rise in sedimentation rate during the period 6.8 - 0.8 Ma is surprisingly not in agreement with the decrease in sediment rate reported at ODP Leg 116 sites in the distal Bengal Fan, but coincident with the change in monsoon intensity. Here we provide well constrained ages for the growth of the Bengal Fan, which can serve as benchmark for interactions between the Himalayan exhumation and Asian climate.

  18. Development of a formulated control sediment for use in whole-sediment toxicity testing

    SciTech Connect

    Kemble, N.E.; Dwyer, F.J.; Ingersoll, C.G.

    1994-12-31

    Because natural bottom sediments may be contaminated with toxicants, it is difficult to obtain a sediment that permits consistent, acceptable biological endpoints (i.e., survival, growth and reproduction) for a variety of species and allows the study of the effects of a single substance to aquatic organisms. Therefore, a formulated control sediment which simulates natural sediments conditions (i.e., particle size and chemical composition) is needed for use in whole-sediment toxicity testing. In an attempt to develop this sediment, two tests were conducted. The first evaluated 11 sources of organic carbon at 2 concentrations (2% and 10%) in a formulated control sediment for 10d. The second sediment test evaluated aging maple leaves (for use as an organic carbon source) for up to 14 days. Three treatments of aged maple leaves were used (1) leaves aged with rabbit manure, (2) leaves aged with cow manure, and (3) leaves without manure treatment. Manure was added to the system to increase the nitrogen and phosphorus concentrations and to aid in leaf degradation. Low dissolved oxygen concentrations in overlying water were observed in 8 of the 11 organic carbon sources. Dissolved oxygen concentrations were consistently low in organic carbon sources. Dissolved oxygen concentrations were consistently low in organic carbon sources. Dissolved oxygen concentrations were consistently low in both the 2% and 10% organic carbon levels of these 8 treatments. Hyalella azteca survival in the 10d organic carbon test was significantly greater in the cow manure exposures (both 2 and 10%) compared to all other organic carbon sources. Preliminary results suggest that aging leaves for two weeks may be an adequate procedure for development of a organic compound source for use in formulating sediment.

  19. Sources of suspended sediment in the Lower Roanoke River, NC

    NASA Astrophysics Data System (ADS)

    Jalowska, A. M.; McKee, B. A.; Rodriguez, A. B.; Laceby, J. P.

    2015-12-01

    The Lower Roanoke River, NC, extends 220 km from the fall line to the bayhead delta front in the Albemarle Sound. The Lower Roanoke is almost completely disconnected from the upper reaches by a series of dams, with the furthest downstream dam located at the fall line. The dams effectively restrict the suspended sediment delivery from headwaters, making soils and sediments from the Lower Roanoke River basin, the sole source of suspended sediment. In flow-regulated rivers, bank erosion, especially mass wasting, is the major contributor to the suspended matter. Additional sources of the suspended sediment considered in this study are river channel, surface soils, floodplain surface sediments, and erosion of the delta front and prodelta. Here, we examine spatial and temporal variations in those sources. This study combined the use of flow and grain size data with a sediment fingerprinting method, to examine the contribution of surface and subsurface sediments to the observed suspended sediment load along the Lower Roanoke River. The fingerprinting method utilized radionuclide tracers 210Pb (natural atmospheric fallout), and 137Cs (produced by thermonuclear bomb testing). The contributions of surface and subsurface sources to the suspended sediment were calculated with 95% confidence intervals using a Monte-Carlo numerical mixing model. Our results show that with decreasing river slope and changing hydrography along the river, the contribution of surface sediments increases and becomes a main source of sediments in the Roanoke bayhead delta. At the river mouth, the surface sediment contribution decreases and is replaced by sediments eroded from the delta front and prodelta. The area of high surface sediment contribution is within the middle and upper parts of the delta, which are considered net depositional. Our study demonstrates that floodplains, often regarded to be a sediment sink, are also a sediment source, and they should be factored into sediment, carbon and

  20. Colonization dynamics of ciliate morphotypes modified by shifting sandy sediments.

    PubMed

    Risse-Buhl, Ute; Felsmann, Katja; Mutz, Michael

    2014-08-01

    Sandy stream-bed sediments colonized by a diverse ciliate community are subject to various disturbance regimes. In microcosms, we investigated the effect of sediment shifting on the colonization dynamics of 3 ciliate morphotypes differing in morphology, behavior and feeding strategy. The dynamics of the ciliate morphotypes inhabiting sediment pore water and overlying water were observed at 3 sediment shifting frequencies: (1) stable sediments, (2) periodically shifting sediments such as migrating ripples, and (3) continuously shifting sediments as occurring during scour events of the uppermost sediment. Sediment shifting significantly affected the abundance and growth rate of the ciliate morphotypes. The free-swimming filter feeder Dexiostoma campylum was vulnerable to washout by sediment shifting since significantly higher numbers occurred in the overlying water than in pore water. Abundance of D. campylum only increased in pore water of stable sediments. On the contrary, the vagile grasper feeder Chilodonella uncinata and the sessile filter feeder Vorticella convallaria had positive growth rates and successfully colonized sediments that shifted periodically and continuously. Thus, the spatio-temporal pattern of sediment dynamics acts as an essential factor of impact on the structure, distribution and function of ciliate communities in sand-bed streams.

  1. Fluvial sediment in the environment: a national challenge

    USGS Publications Warehouse

    Larsen, Matthew C.; Gellis, Allen C.; Glysson, G. Douglas; Gray, John R.; Horowitz, Arthur J.

    2010-01-01

    Sediment and sediment-associated constituents can contribute substantially to water-quality impairment. In the past, sediment was viewed mainly as an engineering problem that affected reservoir storage capacity, shipping channel maintenance, and bridge scour, as well as the loss of agricultural soil. Sediment is now recognized as a major cause of aquatic system degradation in many rivers and streams as a result of light attenuation, loss of spawning substrate due to fine-grained sediment infilling, reduction in primary productivity, decreases in biotic diversity, and effects from sediment-associated chemical constituents. Recent advances in sediment measurement, assessment, source-identification, and analytical protocols provide new capabilities to quantify sediment and solid-phase chemical fluxes in aquatic systems. Developing, maintaining, and augmenting current sediment- and water-quality-monitoring networks is essential for determining the health of U.S. waterways and for evaluating the effectiveness of management actions in reducing sediment-related problems. The application of new scientific capabilities that address the adverse effects of sediment and sediment- associated constituents represents a major step in managing the Nation’s water quality. A robust Federal, national-scale eff rt, in collaboration with vested stakeholders, is needed to address these sediment-related water-quality issues across the United States.

  2. Entrainment at a sediment concentration interface in turbulent channel flow

    NASA Astrophysics Data System (ADS)

    Salinas, Jorge; Shringarpure, Mrugesh; Cantero, Mariano; Balachandar, S.

    2016-11-01

    In this work we address the role of turbulence on entrainment at a sediment concentration interface. This process can be conceived as the entrainment of sediment-free fluid into the bottom sediment-laden flow, or alternatively, as the entrainment of sediment into the top sediment-free flow. We have performed direct numerical simulations for fixed Reynolds and Schmidt numbers while varying the values of Richardson number and particle settling velocity. The analysis performed shows that the ability of the flow to pick up a given sediment size decreases with the distance from the bottom, and thus only fine enough sediment particles are entrained across the sediment concentration interface. For these cases, the concentration profiles evolve to a final steady state in good agreement with the well-known Rouse profile. The approach towards the Rouse profile happens through a transient self-similar state. Detailed analysis of the three dimensional structure of the sediment concentration interface shows the mechanisms by which sediment particles are lifted up by tongues of sediment-laden fluid with positive correlation between vertical velocity and sediment concentration. Finally, the mixing ability of the flow is addressed by monitoring the center of mass of the sediment-laden layer. With the support of ExxonMobil, NSF, ANPCyT, CONICET.

  3. Catchment sediment flux: a lake sediment perspective on the onset of the Anthropocene?

    NASA Astrophysics Data System (ADS)

    Chiverrell, Richard

    2014-05-01

    Definitions of the Anthropocene are varied but from a geomorphological perspective broadly can be described as the interval of recent Earth history during which 'humans have had an 'overwhelming' effect on the Earth system' (Brown et al., 2013). Identifying the switch to a human-dominated geomorphic process regime is actually a challenging process, with in the 'Old World' ramping up of human populations and impacts on earth surface processes since the Neolithic/Mesolithic transition and the onset of agriculture. In the terrestrial realm lakes offer a unique window on changes in human forcing of earth surface processes from a sedimentary flux perspective, because unlike alluvial and hill-slope systems sedimentation is broadly continuous and uninterrupted. Dearing and Jones (2003) showed for a global dataset of lakes a 5-10 fold increase in sediment delivery comparing pre- and post-anthropogenic disturbance. Here sediment records from several lakes in lowland agricultural landscapes are presented to examine the changes in the flux and composition of materials delivered from their catchments. By definition the lakes record the switch to a human dominated system, but not necessary in accelerated sediment accumulation rates with changes in sediment composition equally important. Data from Crose, Hatch and Peckforton Meres, in lowland northwest England are interrogated producing quantitative land-cover reconstructions from pollen spectra calculated using the REVEALS model (Sugita, 2007), geochemical evidence for changes sediment provenance and flux, and 14C and stable Pb pollutant based chronological models detecting changes in sediment accumulation rate. The lake sediment geochemistry points to several phases of heightened human impact within these small agricultural catchments. Following small-in-scale forest cover reductions and limited impacts in terms of sediment flux during the Neolithic, the Bronze to Iron Age saw the first substantial reductions in forest cover

  4. RESULTS OF APPLYING TOXICITY IDENTIFICATION PROCEDURES TO FIELD COLLECTED SEDIMENTS

    EPA Science Inventory

    Identification of specific causes of sediment toxicity can allow for much more focused risk assessment and management decision making. We have been developing toxicity identification evaluation TIE) methods for contaminated sediments and are focusing on three toxicant groups (amm...

  5. Urban Runoff: Model Ordinances for Erosion and Sediment Control

    EPA Pesticide Factsheets

    The model ordinance in this section borrows language from the erosion and sediment control ordinance features that might help prevent erosion and sedimentation and protect natural resources more fully.

  6. Impact Of Groundwater Discharge On Contaminant Behavior In Sediments

    EPA Science Inventory

    The discharge of groundwater into surface water may influence the concentrations and availability of contaminants in sediments. There are three predominant pathways by which groundwater may affect the characteristics of contaminated sediments: 1) direct contribution of contamin...

  7. Characterization of bottom sediments from Osaka Bay, Japan

    NASA Astrophysics Data System (ADS)

    Tokunaga, S.; Hoshika, A.; Tatsumoto, H.

    1995-06-01

    The physical, chemical, and dewatering characteristics of 19 bottom sediments from Osaka Bay, Japan, have been analyzed to aid in the development of sediments in the coastal bay area. The sediments in the east near Osaka Port were highly polluted from the influence of human activities and were difficult to dewater. These sediments were composed of fine particles, low in pH, zetapotential, and initial settling rate, and were high in ignition loss, metal concentrations, compression volume, specific resistance, cake water content, and drying index. However, the sediments near Akashi Channel showed the reverse where they are affected by strong tidal current. A correlation analysis has been made of all the parameters. There are significant relationships between all the dewatering parameters. Therefore, sediments difficult to dewater by gravity settling are also difficult to dewater by vacuum filtration and solar evaporation. Sediments containing fine particles and pollutants are difficult to dewater. Several forms of pollutants can occur in the sediments.

  8. IDENTIFICATION OF TOXICANTS IN WHOLE MARINE SEDIMENTS: METHODS AND RESULTS

    EPA Science Inventory

    Identification of stressors in aquatic systems is critical to sound assessment and management of our nation's waterways. Information from stressor identification can be useful in designing effective sediment remediation methods, assessing options for sediment disposal, allowing m...

  9. List of Contaminated Sediments Technical Advisory Group Sites

    EPA Pesticide Factsheets

    The Contaminated Sediments Technical Advisory Group provides advice to large, complex, or controversial contaminated sediment sites. On this page are the operating procedures, the list of CSTAG sites, and CSTAG recommendations on each site.

  10. IDENTIFICATION OF SEDIMENT SOURCE AREAS WITHIN A WATERSHED

    EPA Science Inventory

    Identification of sediment source areas is crucial for designing proper abatement strategies that reduce sediment and associated contaminant loading to receiving water downstream. In this study, two methodologies were developed to identify the source areas and their relative stre...

  11. Sediment transport-based metrics of wetland stability

    NASA Astrophysics Data System (ADS)

    Ganju, Neil K.; Kirwan, Matthew L.; Dickhudt, Patrick J.; Guntenspergen, Glenn R.; Cahoon, Donald R.; Kroeger, Kevin D.

    2015-10-01

    Despite the importance of sediment availability on wetland stability, vulnerability assessments seldom consider spatiotemporal variability of sediment transport. Models predict that the maximum rate of sea level rise a marsh can survive is proportional to suspended sediment concentration (SSC) and accretion. In contrast, we find that SSC and accretion are higher in an unstable marsh than in an adjacent stable marsh, suggesting that these metrics cannot describe wetland vulnerability. Therefore, we propose the flood/ebb SSC differential and organic-inorganic suspended sediment ratio as better vulnerability metrics. The unstable marsh favors sediment export (18 mg L-1 higher on ebb tides), while the stable marsh imports sediment (12 mg L-1 higher on flood tides). The organic-inorganic SSC ratio is 84% higher in the unstable marsh, and stable isotopes indicate a source consistent with marsh-derived material. These simple metrics scale with sediment fluxes, integrate spatiotemporal variability, and indicate sediment sources.

  12. Sediment transport-based metrics of wetland stability

    USGS Publications Warehouse

    Ganju, Neil K.; Kirwan, Matthew L.; Dickhudt, Patrick J.; Guntenspergen, Glenn R.; Cahoon, Donald R.; Kroeger, Kevin D.

    2015-01-01

    Despite the importance of sediment availability on wetland stability, vulnerability assessments seldom consider spatiotemporal variability of sediment transport. Models predict that the maximum rate of sea level rise a marsh can survive is proportional to suspended sediment concentration (SSC) and accretion. In contrast, we find that SSC and accretion are higher in an unstable marsh than in an adjacent stable marsh, suggesting that these metrics cannot describe wetland vulnerability. Therefore, we propose the flood/ebb SSC differential and organic-inorganic suspended sediment ratio as better vulnerability metrics. The unstable marsh favors sediment export (18 mg L−1 higher on ebb tides), while the stable marsh imports sediment (12 mg L−1 higher on flood tides). The organic-inorganic SSC ratio is 84% higher in the unstable marsh, and stable isotopes indicate a source consistent with marsh-derived material. These simple metrics scale with sediment fluxes, integrate spatiotemporal variability, and indicate sediment sources.

  13. Sediment calibration strategies of Phase 5 Chesapeake Bay watershed model

    USGS Publications Warehouse

    Wu, J.; Shenk, G.W.; Raffensperger, J.; Moyer, D.; Linker, L.C.; ,

    2005-01-01

    Sediment is a primary constituent of concern for Chesapeake Bay due to its effect on water clarity. Accurate representation of sediment processes and behavior in Chesapeake Bay watershed model is critical for developing sound load reduction strategies. Sediment calibration remains one of the most difficult components of watershed-scale assessment. This is especially true for Chesapeake Bay watershed model given the size of the watershed being modeled and complexity involved in land and stream simulation processes. To obtain the best calibration, the Chesapeake Bay program has developed four different strategies for sediment calibration of Phase 5 watershed model, including 1) comparing observed and simulated sediment rating curves for different parts of the hydrograph; 2) analyzing change of bed depth over time; 3) relating deposition/scour to total annual sediment loads; and 4) calculating "goodness-of-fit' statistics. These strategies allow a more accurate sediment calibration, and also provide some insightful information on sediment processes and behavior in Chesapeake Bay watershed.

  14. APPLYING TOXICITY IDENTIFICATION PROCEDURES TO FIELD COLLECTED SEDIMENTS

    EPA Science Inventory

    Identification of specific causes of sediment toxicity can allow for much more focused risk assessment and management decision making. We have been developing toxicity identification evaluation (TIE) methods for contaminated sediments and focusing on three toxicant groups (ammoni...

  15. USDA-ARS National Sedimentation Laboratory: A historic perspective

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sediment from soil erosion is conceded by most authorities to be the largest single stream pollutant. Physical damage from sediment include reservoir storage loss, navigation channel filling, stream channel morphology alterations, ecological impacts, and clogging of drainage pathways. Ultimately, so...

  16. AN OVERVIEW OF TOXICANT IDENTIFICATION IN SEDIMENTS AND DREDGED MATERIALS

    EPA Science Inventory

    The identification of toxicants affecting aquatic benthic systems is critical to sound assessment and management of our nation?s waterways. Identification of toxicants can be useful in designing effective sediment remediation plans and reasonable options for sediment disposal. K...

  17. DISSIPATION OF PAHs IN SATURATED, DREDGED SEDIMENTS: A FIELD TRIAL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sediments dredged from navigable rivers often contain elevated concentrations of recalcitrant, potentially toxic organic compounds such as polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). The presence of these compounds often requires that the sediments be stored in fully conta...

  18. A field study on phytoremediation of dredged sediment contaminated by heavy metals and nutrients: the impacts of sediment aeration.

    PubMed

    Wu, Juan; Yang, Lihua; Zhong, Fei; Cheng, Shuiping

    2014-12-01

    Compared to traditional chemical or physical treatments, phytoremediation has proved to be a cost-effective and environmentally sound alternative for remediation of contaminated dredged sediment. A field study was conducted in a sediment disposal site predominantly colonized by Typha angustifolia under different sediment moisture conditions to estimate the phytoremediation effects of dredged sediment. The moisture content was 37.30 % and 48.27 % in aerated and waterlogged sediment, respectively. Total nitrogen (TN) content was higher in the waterlogged sediment than in the aerated sediment. The total Cd contents were lower in aerated sediment, which was mainly resulted from the lower exchangeable fraction of Cd. The bioaccumulation of P, Cu and Pb in T. angustifolia was promoted by waterlogging, and the belowground tissue concentrations and accumulation factors (AFs) of Cu were higher than that of other metals, which can be explained by that Cu is an essential micronutrient for plants. Consistent with many previous studies, T. angustifolia showed higher metal levels in roots than in above-ground tissues at both the sediment conditions. Due to the improved biomass produced in the aerated sediment, the removals of nutrients and the metals by plant harvest were higher from aerated sediment than from waterlogged sediment. It was indicated that maintaining the dredged sediment aerated can avoid release risk and plant uptake of metals, while the opposite management option can promote phytoextraction of these contaminants.

  19. Effect of sediment particle size on polycyclic aromatic hydrocarbon biodegradation: importance of the sediment-water interface.

    PubMed

    Xia, Xinghui; Wang, Ran

    2008-01-01

    Mechanisms for the effects of sediment on the biodegradation of organic compounds in the aquatic environment are not clear. In this research, effects of sediment characteristics on biodegradation kinetics of chrysene and benzo[a]pyrene were studied by inoculating polycyclic aromatic hydrocarbon (PAH)-degrading bacteria. Because water and PAHs can pass a polytetrafluoroethylene membrane yet bacteria and sediment cannot, a membrane experiment was performed to compare the biodegradation rates of PAHs in water and at the sediment-water interface, providing direct evidence that the PAH biodegradation rate is enhanced by the presence of sediment. Biodegradation of PAHs in water-sediment systems was fitted to zero-order kinetics; the order of biodegradation rate in water-sediment systems with different sediment was fine silt > clay > coarse silt. Biodegradation of PAHs in water-sediment systems occurred mainly at the sediment-water interface. According to membrane experiment results, when the biodegradation kinetics was fit to a zero-order equation, the maximum specific growth rates of bacteria (1/d) at the sediment-water interface were approximately three- to fourfold those in the water phase. Furthermore, the associated mechanisms regarding the effect of sediment characteristics were analyzed by investigating the process of bacterial growth and the distribution of bacteria and PAHs between water and sediment phases.

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

    SciTech Connect

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

    1995-08-01

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

  1. LITERATURE REVIEW AND REPORT: SURFACE-SEDIMENT ...

    EPA Pesticide Factsheets

    A literature review was conducted to identify available surface sediment sampling technologies with an ability to collect undisturbed sediments to depths of up to 1 meter below the water sediment interface. This survey was conducted using published literature and references, Environmental Protection Agency reports, professional sources, journal articles, internet web sites, sales brochures, and other sources as identified. For each piece of sampling equipment or sampling tool identified during the literature search, the following information was collected: general description of the equipment or tool, including its size, shape, weight, and composition; manufacturer's name, address, phone number, and email; a picture of the equipment or tool; the general mechanism of operation; sample volume collected; chemical and physical compatibility concerns; labor requirements; cost; and other requirements such as electrical power or specialized training. Sampling methodologies included in this investigation are grab or core types of sampling devices, as these types are most typically used in collecting surface sediments. In this review, 40 samplers were identified that included 13 grab samplers and 27 core samplers. Grab samplers included in the review are the Ponar, Birge-Ekman, Van Veen, Peterson, Mud Snapper, Scoopfish, Shipek, Smith-McIntyre, and others. Core samplers included in the review are the piston, splitcore, box, Vibracore, Mackereth, Ballchek, Craib, Gomex,

  2. Elastic properties of overpressured and unconsolidated sediments

    USGS Publications Warehouse

    Lee, Myung W.

    2003-01-01

    Differential pressure affects elastic velocities and Poisson?s ratio of sediments in such a way that velocities increase as differential pressure increases. Overpressured zones in sediments can be detected by observing an increase in Poisson?s ratio with a corresponding drop in elastic velocities. In highly overpressured sands, such as shallow water flow sands, the P-to S-wave velocity ratio (Vp/Vs) is very high, on the order of 10 or higher, due to the unconsolidated and uncemented nature of sediments. In order to predict elastic characteristics of highly overpressured sands, Biot-Gassmann theory by Lee (BGTL) is used with a variable exponent n that depends on differential pressure and the degree of consolidation/compaction. The exponent n decreases as differential pressure and the degree of consolidation increases, and, as n decreases, velocity increases and Vp/Vs decreases. The predicted velocity ratio by BGTL agrees well with the measured velocity ratio at low differential pressure for unconsolidated sediments.

  3. The Community Sediment Transport Modeling System

    DTIC Science & Technology

    2008-01-01

    addition to wave processes, the model includes the influence of flocculation, hindered settling, rheology, and turbulence -suppression by stratification...The extensive upwelling event occurred in March 2002 is better reproduced with evident appearance of submesoscale spiral eddies all over the inner...THE COMMUNITY SEDIMENT TRANSPORT MODELING SYSTEM W. Rockwell Geyer Woods Hole Oceanographic Institution MS 11, Woods Hole, MA 02543 phone

  4. Par Pond Fish, Water, and Sediment Chemistry

    SciTech Connect

    Paller, M.H.; Wike, L.D.

    1996-06-01

    The objectives of this report are to describe the Par Pond fish community and the impact of the drawdown and refill on the community, describe contaminant levels in Par Pond fish, sediments, and water and indicate how contaminant concentrations and distributions were affected by the drawdown and refill, and predict possible effects of future water level fluctuations in Par Pond.

  5. Quantifying Seepage Flux using Sediment Temperatures

    EPA Science Inventory

    This report provides a demonstration of different modeling approaches that use sediment temperatures to estimate the magnitude and direction of water flux across the groundwater-surface water transition zone. Analytical models based on steady-state or transient temperature solut...

  6. Carbonate to siliciclastic periplatform sediments: southwest Florida

    USGS Publications Warehouse

    Holmes, Charles W.

    1988-01-01

    Geophysical, geochemical, and sedimentological data suggest that the spatial relationships of these deposits are related to sea-level variations. During extreme lowstands, with much of the shelf exposed, the dominant sedimentation was in the form of siliciclastic deposition on the abyssal floor, and slope talus development at the edge of the shelf. During a subsequent rise in sea level, after carbonate production on the shelf was initiated, sediment was transported southward to the head of the canyons and funneled to the abyssal floor. Subsequent rising sea level shifted the axis of transport farther to the shelf, bypassing the canyons and funneling the sediment through breaks in the carbonate reef banks at the southern edge of the platform. At the sites of both the hemipelagic and the turbidite deposition, high-resolution seismic data indicate that at least three cycles of deposition have occurred. In the abyss, this cyclic nature has produced alternating layers of carbonate and noncarbonate sediments, recognizable in the sedimentary record as limestone units interlayered with fine shales. In the geologic record the hemipelagic deposits would be almost indistinguishable from deep-sea foraminiferal oozes.  

  7. Arsenate adsorption by unsaturated alluvial sediments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Arsenate adsorption as a function of solution arsenic concentration and solution pH was investigated on five alluvial sediments from the Antelope Valley, Western Mojave Desert, California. Arsenate adsorption increased with increasing solution pH, exhibited a maximum around pH 4 to 5, and then decr...

  8. Integrated Model for the Acoustics of Sediments

    DTIC Science & Technology

    2013-09-30

    Eng. 27, 3, 413-428, (2002). 2. R. D. Stoll. "Velocity dispersion in water- saturated granular sediment," J. Acoust. Soc. Am. 111, 2, 785-793, (2002...Goff, B. J. Kraft , L. A. Mayer, S. G. Schock, C. K. Sommerfield, H. C. Olson, S. P. S. Gulick, and S. Nordfjord. "Seabed characterization on the New

  9. Magnetostratigraphy of sediments in mammoth cave, kentucky.

    PubMed

    Schmidt, V A

    1982-08-27

    Clastic sediment deposits found within the caves of Mammoth Cave National Park have yielded a magnetostratigraphic pattern of magnetic polarity reversals which indicates-that they were deposited over a range of at least 1 million and most likely 2 million years.

  10. Magnetostratigraphy of Sediments in Mammoth Cave, Kentucky

    NASA Astrophysics Data System (ADS)

    Schmidt, Victor A.

    1982-08-01

    Clastic sediment deposits found within the caves of Mammoth Cave National Park have yielded a magnetostratigraphic pattern of magnetic polarity reversals which indicates that they were deposited over a range of at least 1 million and most likely 2 million years.

  11. Suspended Sediments Measured in the Surf Zone.

    DTIC Science & Technology

    1977-09-01

    described by Komar and Inman (1970). Sus- pended sediments were measured in situ by swimmers using a mechanical water sampling device which...PEÜüENC’-1 fH* 39 imt ^^m "/• ffr- 7 If) \\ h A /’ kl v \\ n/\\ i > ^ U, Vectra of onshore-offshore flow vs. nephelcmeter

  12. Upper Washita River experimental watersheds: Sediment Database

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improving the scientific understanding of the effectiveness of watershed conservation practices and floodwater-retardation structures to control floods and soil erosion is one of the primary objectives for sediment studies in the upper Washita River Experimental Watersheds. This paper summarizes se...

  13. Leishmania (infantum) chagasi in canine urinary sediment.

    PubMed

    de Mendonça, Ivete Lopes; Batista, Joilson Ferreira; Alves, Leucio Camara

    2015-01-01

    Canine visceral leishmaniasis (CVL) is difficult to diagnosis, mainly due to the presence of asymptomatic animals, the diversity of clinical symptoms and the difficulty in obtaining diagnostic evidence of high sensitivity and specificity. The purpose of this study was to diagnose CVL in urinary sediment of 70 dogs of different breeds, sexes and ages from the veterinary hospital of the Federal University of Piauí and Zoonosis Control Center of Teresina, Brazil. The serological tests were TR DPP® for CVL and enzyme-linked immunosorbent assay (ELISA) for CVL, parasitological exams of bone marrow and lymph nodes and urine sediment cultures. Leishmania was detected in the bone marrow and/or lymph node of 61.0% of the animals (43/70), and urine sediment culture was positive in 9.30% (4/43) of these animals. In the serological exams, 70.0% (49/70) were reactive using the DPP and 78.2% (55/70) were reactive using ELISA. The goal of this study was to diagnose the presence of L. (infantum) chagasi in a culture of urinary sediment.

  14. Sulfate reduction in deep-sea sediments

    NASA Technical Reports Server (NTRS)

    Canfield, D. E.

    1991-01-01

    Sulfate reduction rates calculated from about 200 DSDP pore water sulfate profiles have been contoured and plotted on a map covering most areas of the world ocean. Rates show a remarkable spatial consistency, with high rates observed near the continental margins, becoming progressively lower toward the central ocean basins. Relatively elevated rates are also found in the eastern equatorial Pacific, a site of upwelling and correspondingly high rates of primary organic production. Overall, the distribution of sulfate reduction in pelagic sediments looks very similar to the distribution of primary organic carbon production. When rates are directly compared, however, the correlation between sulfate reduction and primary production is only moderately strong. Perhaps the most important influence on sulfate reduction is sediment deposition rate and the control this has over the fraction of the sedimentary organic carbon flux that becomes available for sulfate reduction. The slower the rate of sediment deposition the more time for oxic respiration and the less organic carbon that escapes to the zone of sulfate reduction. To predict most accurately sulfate reduction rates, however, the variables of primary production, water depth, and sediment deposition rate must all be integrated.

  15. TOXICITY TESTS FOR SEDIMENT QUALITY ASSESSMENTS

    EPA Science Inventory

    Toxic sediments have contributed to a wide-variety of environmental problems around the world. The observed effects include direct toxic effects to aquatic life, bio-magnification of toxicants in the food chain, and economic impacts. This chapter discusses the use of toxicity...

  16. Hawaii Regional Sediment Management Needs Assessment

    DTIC Science & Technology

    2014-07-01

    innovative solutions in civil and military engineering, geospatial sciences, water resources, and environmental sciences for the Army, the...a) basic sediment processes, (b) engineered solutions , (c) RSM tools, (d) informatics, and (e) technology transfer and insertion. Purpose of the...composed of rejuvenated volcanic basalt. The shoreline is characterized mostly by embayments and fringing reef systems. The shore is exposed to large

  17. 7 CFR 58.134 - Sediment content.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... classified for sediment content, regardless of the results of the appearance and odor examination required in...: (1) Milk in cans. One or more cans of milk selected at random from each producer. (2) Milk in farm... shipments and accepting probational (No. 3) milk and rejecting No. 4 milk may be continued for not more...

  18. Clinton River Sediment Transport Modeling Study

    EPA Pesticide Factsheets

    The U.S. ACE develops sediment transport models for tributaries to the Great Lakes that discharge to AOCs. The models developed help State and local agencies to evaluate better ways for soil conservation and non-point source pollution prevention.

  19. A Sedimentation Experiment Using a Preparative Ultracentrifuge

    ERIC Educational Resources Information Center

    Boudreau, Raymond E.; And Others

    1975-01-01

    Describes an experiment that illustrates the use of the preparative ultracentrifuge in isolating and purifying bacterial ribosomes, determines the sedimentation coefficients of the ribonucleoprotein particles, and demonstrates the subunit structure of the 70-S ribosome and the role of the magnesium ion in the association of subunits. (Author/GS)

  20. Size of Suspended Sediment Over Dunes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Samples of suspended sediment were collected at four elevations simultaneously over two-dimensional mobile dunes in 0.5 mm sand in a laboratory flume channel. A constant sampling position relative to the dunes was maintained by adjusting the translation rate of the sampling carriage to be the same ...

  1. Size of Suspended Sediment over Dunes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Samples of suspended sediment were collected at four elevations simultaneously over two-dimensional mobile dunes in two mixtures of 0.5 mm sand in a laboratory flume channel. A constant sampling position relative to the dunes was maintained by adjusting the translation rate of the sampling carriage...

  2. Sediment transport in shallow overland flow

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil erosion is a highly complicated phenomenon consisting of many component processes. On upland areas, these processes are usually thought of as detachment and transport of soil particles by rainfall and surface flow. One of the most difficult processes to quantify is sediment transport. This proc...

  3. Seismoelectric Phenomena in Fluid-Saturated Sediments

    SciTech Connect

    Block, G I; Harris, J G

    2005-04-22

    Seismoelectric phenomena in sediments arise from acoustic wave-induced fluid motion in the pore space, which perturbs the electrostatic equilibrium of the electric double layer on the grain surfaces. Experimental techniques and the apparatus built to study this electrokinetic (EK) effect are described and outcomes for studies of seismoelectric phenomena in loose glass microspheres and medium-grain sand are presented. By varying the NaCl concentration in the pore fluid, we measured the conductivity dependence of two kinds of EK behavior: (1) the electric fields generated within the samples by the passage of transmitted acoustic waves, and (2) the electromagnetic wave produced at the fluid-sediment interface by the incident acoustic wave. Both phenomena are caused by relative fluid motion in the sediment pores--this feature is characteristic of poroelastic (Biot) media, but not predicted by either viscoelastic fluid or solid models. A model of plane-wave reflection from a fluid-sediment interface using EK-Biot theory leads to theoretical predictions that compare well to the experimental data for both sand and glass microspheres.

  4. Synchrotron Analysis Of Metal Immobilization In Sediments

    EPA Science Inventory

    Heavy metal contamination is a problem at many marine and fresh water environments as a result of industrial and military activities. Metals such as lead (Pb), zinc (Zn), copper (Cu), and chromium (Cr) are common contaminants in sediments due to many Navy activities. The mobile...

  5. Roughness configuration matters for aeolian sediment flux

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The parameterisation of surface roughness effects on aeolian sediment transport is a key source of uncertainty in wind erosion models. Roughness effects are typically represented by bulk drag-partitioning schemes that scale the threshold friction velocity (u*t) for soil entrainment by the ratio of s...

  6. Formulas for sediment porosity and settling velocity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The formulas of Komura (1963) and Han et al. (1981) for the initial porosity of sediment deposits were tested using data sets collected in different countries and regions. It was found that Komura’s formula slightly underestimates the dry density for sand and gravel deposits and overestimates those ...

  7. SEDIMENT TOXICOLOGY TESTING, ISSUES AND METHODS

    EPA Science Inventory

    The significant role that sediments play in aquatic ecosystems is well known. They serve as both a sink and a source of organic and inorganic materials, where critical cycling processes for organic matter and the critical elements (e.g., C, N, P, and S). The majority of decomposi...

  8. A Field Exercise in Fluvial Sediment Transport.

    ERIC Educational Resources Information Center

    Tharp, Thomas M.

    1983-01-01

    Describes an investigation which introduces the mathematical principles of stream hydraulics and fluvial sediment in a practical context. The investigation has four stages: defining hydrology of the stream; defining channel hydraulics in a study reach; measuring grain size; and calculating transportable grain size and comparing measure stream-bed…

  9. Chlorinated organic compounds in urban river sediments

    SciTech Connect

    Soma, Y.; Shiraishi, H.; Inaba, K.

    1995-12-31

    Among anthropogenic chemicals, many chlorinated organic compounds have been used as insecticides and detected frequently as contaminants in urban river sediments so far. However, the number and total amount of chemicals produced commercially and used are increasing year by year, though each amount of chemicals is not so high. New types of contaminants in the environment may be detected by the use of newly developed chemicals. Chlorinated organic compounds in the urban river sediments around Tokyo and Kyoto, large cities in Japan, were surveyed and recent trends of contaminants were studied. Contaminants of the river sediments in industrial areas had a variety, but PCB (polychlorinated biphenyls) was detected in common in industrial areas. Concentration of PCB related well to the number of factories on both sides of rivers, although the use of PCB was stopped 20 years ago. In domestic areas, Triclosan (5-chloro-2-(2,4-dichlorophenoxy)-phenol) and Triclocarban (3,4,4{prime}-trichlorocarbanilide)(both are contained in soap or shampoo for fungicides), p-dichlorobenzene (insecticides for wears) and TCEP(tris-chloroethyl phosphate) were detected. EOX(extracted organic halogen) in the sediments was 5 to 10 times of chlorinated organic compounds detected by GC/MS. Major part of organic halogen was suggested to be included in chlorinated organics formed by bleaching or sterilization.

  10. Mineralogical Signatures in Electrically Coupled Marine Sediments

    NASA Astrophysics Data System (ADS)

    Bauermeister, A.; Gorby, Y. A.; Schramm, J.

    2014-12-01

    'Electric cable bacteria' are organisms of the family Desulfobulbaceaethat exhibit a novel method of electron transport. Cells form conductive filaments that function like electric wires, transferring electrons over distances of more than 1 cm from deep sulfidic sediments to oxygen or other electron acceptors near the soil/water interface. The rate of electron transfer across redox boundaries far exceeds that of diffusion limited processes and generates pH gradients that can significantly influence geochemical reactions, leading to the formation of distinct mineralogical profiles unlikely to be created by abiotic means. Electrically coupled sediments are characterized by carbonate and iron sulfide dissolution reactions occurring at depth and formation of carbonate and metal oxide crusts at the surface, exhibiting a reverse pattern compared to conventional sediment geochemistry. Our research seeks to address the following questions: How prevalent are electric cable bacteria in diverse environments? How do biogeochemical conditions such as ion concentration influence mineral formation? Do biogenic minerals participate in charge transfer? What is the importance of electric charge transfer in the subsurface or other low energy habitats? Can mineral banding patterns caused by cable bacteria activity be preserved in the geologic record? With this research we hope to further elucidate the impact of biologically-induced electric fields on the mineralogy of sediments.

  11. Contaminated Sediments at Navy Facilities: Cleanup Alternatives

    DTIC Science & Technology

    2007-11-02

    catalyzed decomposition (destruction) • Electrokinetics (destruction) Biological Methods • Biopile /composting (destruction) • Slurry-phase bioreactors...incineration, vitrification, $110 to $1,350 • Sediment washing, $81 to $330 • Solidification/stabilization, $81 to $392 • Biopile /composting

  12. BIOREMEDIATION OF OIL-CONTAMINATED FINE SEDIMENTS.

    EPA Science Inventory

    Bioremediation of oil contamination has been shown to be effective for cobble and sandy shorelines. To assess the operational limitations of this technology, this project studied its potential to treat buried oil in fine sediments. The effectiveness of bioremediation by nutrient ...

  13. Contaminated sediment dynamics in peatland headwaters

    NASA Astrophysics Data System (ADS)

    Shuttleworth, Emma; Clay, Gareth; Evans, Martin; Hutchinson, Simon; Rothwell, James

    2016-04-01

    Peatlands are an important store of soil carbon, provide multiple ecosystem services, and when located in close proximity to urban and industrial areas, can also act as sinks of atmospherically deposited heavy metals. The near-surface layer of the blanket peats of the Peak District National Park, UK, is severely contaminated with high concentrations of anthropogenically derived, atmospherically deposited lead (Pb). These peats are severely degraded, and there is increasing concern that erosion is releasing considerable quantities of this legacy pollution into surface waters. Despite substantial research into Pb dynamics in peatlands formal description of the possible mechanisms of contaminated sediment mobilisation is limited. However, there is evidence to suggest that a substantial proportion of contaminated surface sediment may be redistributed elsewhere in the catchment. This study uses the Pb contamination stored near the peat's surface as a fingerprint to trace contaminated sediment dynamics and storage in three severely degraded headwater catchments. Erosion is exposing high concentrations of Pb on interfluve surfaces, and substantial amounts of reworked contaminated material are stored on other catchment surfaces (gully walls and floors). We propose a variety of mechanisms as controls of Pb release and storage on the different surfaces, including: (i) wind action on interfluves; (ii) the aspect of gully walls, and (iii) gully depth. Vegetation also plays an important role in retaining contaminated sediment on all surfaces.

  14. Effects of intensive mariculture on sediment biochemistry.

    PubMed

    Pusceddu, Antonio; Fraschetti, Simonetta; Mirto, Simone; Holmer, Marianne; Danovaro, Roberto

    2007-07-01

    The exponential growth of off-shore mariculture that has occurred worldwide over the last 10 years has raised concern about the impact of the waste produced by this industry on the ecological integrity of the sea bottom. Investigations into this potential source of impact on the biochemistry of the sea floor have provided contrasting results, and no compelling explanations for these discrepancies have been provided to date. To quantify the impact of fish-farm activities on the biochemistry of sediments, we have investigated the quantity and biochemical composition of sediment organic matter in four different regions in the temperate-warm Mediterranean Sea: Akrotiri Bay (Cyprus), Sounion Bay (Greece), Pachino Bay (Italy), and the Gulf of Alicante (Spain). In these four study regions, the concentrations of phytopigments, proteins, carbohydrates, and lipids in the sediments were measured, comparing locations receiving wastes from fish farms to control locations in two different habitats: seagrass beds and soft nonvegetated substrates. Downward fluxes were also measured in all of the regions, up to 200 m from the fish farms, to assess the potential spatial extent of the impact. In all four regions, with the exception of seagrass sediments in Spain, the biochemistry of the sediments showed significant differences between the control and fish-farm locations. However, the variables explaining the differences observed varied among the regions and between habitats, suggesting idiosyncratic effects of fish-farm waste on the biochemistry of sediments. These are possibly related to differences in the local physicochemical variables that could explain a significant proportion of the differences seen between the control and fish-farm locations. Biodeposition derived from the fish farms decreased with increasing distance from the fish-farm cages, but with different patterns in the four regions. Our results indicate that quantitative and qualitative changes in the organic loads of

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

    EPA Science Inventory

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

  16. Comparing Sediment and Pore-water Measurements as Predictors of PCB Uptake by Oligochaetes from Sediments

    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...

  17. Flocculation and Settling Velocity Estimates for Reservoir Sedimentation Analysis

    DTIC Science & Technology

    2016-02-01

    physical sediment process descriptions (relevant to reservoir sedimentation and sediment bypassing) into U.S. Army Corps of Engineers (USACE) numerical...assortment of physical , chemical, and biological factors. A key component of fine-sediment dynamics is the settling process resulting in deposition of... physical , chemical, and biological processes and are associated with apparent densities between 1,010 and 1,200 kilograms per cubic meter (kg/m3) (van

  18. Erythrocyte sedimentation rate and C-reactive protein.

    PubMed

    Harrison, Michael

    2015-06-01

    C-reactive protein is a better indicator of inflammation than the erythrocyte sedimentation rate. It is more sensitive and responds more quickly to changes in the clinical situation. False negative and false positive results are more common when measuring the erythrocyte sedimentation rate. Renal disease, female sex and older age increase the erythrocyte sedimentation rate. The erythrocyte sedimentation rate has value in detecting low-grade bone infection, and in monitoring some patients with systemic lupus erythematosus.

  19. /sup 137/Cs radioactive dating of Lake Ontario sediment cores

    SciTech Connect

    Ward, T.E.; Breeden, J.; Komisarcik, K.; Porter, R.; Czuczwa, J.; Kaminski, R.; McVeety, B.D.

    1987-12-01

    The distribution of /sup 137/Cs in sediment cores from Lake Ontario provides estimates of the sediment accumulation rates. Geochronology with /sup 210/Pb dating and distribution of Ambrosia (ragweed) pollen compare well with /sup 137/Cs dating. These methods can determine with precision, changes in sedimentation occurring over the past 100 years or so. Typical sedimentation rates of 0.18-0.36 cm/yr were measured. 16 refs., 3 figs., 2 tabs.

  20. Sediment discharge from highway construction near Port Carbon, Pennsylvania

    USGS Publications Warehouse

    Helm, Robert E.

    1978-01-01

    About 16,000 tons of suspended-sediment was discharged from the basin during the construction. The highway construction produced about 8,000 tons or 50 percent of the total sediment discharge. Steep slopes, the availability of fine coal wastes, coal-washing operations, and other land uses in the basin were responsible for most of the remaining sediment discharge. Seventy percent of the total suspended-sediment discharge occurred during eight storms.

  1. Hydrodynamic Conditions and Sediment Movement at Port of Port Orford

    DTIC Science & Technology

    2015-05-15

    pathways of sediment particles deposited in the port’s navigation channel. The current fields show the wind driven flow pattern. Extreme winter storms ...sediment transport pathways during storms . Wave actions in coastal areas are more likely to enhance the transport of sediment due to wave-induced...harbor shoaling due to storm induced sediment transport and breakwater degradation. Without periodic maintenance dredging, vessel access to the

  2. Use of Sediment Trend Analysis (STA) (Registered) for Coastal Projects

    DTIC Science & Technology

    2005-06-01

    Washington: Department of Ecology: Toxics Cleanup Program) 568 1994 Sediment trend analysis (STA) of Anacostia River Baltimore District (as part of...during storm periods, transport by ocean currents, and sediment carried by river flows and deposited from the sediment plume in the nearshore region...specific site will be based on the number of different types of sediment environments thought to be present, e.g., beach sand, river silt deposits, etc

  3. Geophysical Constraints on Sediment Dispersal Systems

    NASA Astrophysics Data System (ADS)

    Johnstone, Elizabeth Anne Carruthers

    Geophysical and geological approaches were employed to understand sediment dispersal systems and their response to various forcing functions (i.e., sea level fluctuations, tectonic deformation, sediment supply, and climate change). Two end member marine environments were studied; one with high precipitation and sediment discharge (Gulf of Papua, Papua New Guinea) and the other with low precipitation and sediment discharge (Oceanside Littoral Cell). The high-sedimentation rate in the Gulf of Papua (GoP) yields high-fidelity records of Earth history. As part of the NSF Margins Source-to-Sink (S2S) program, we acquired CHIRP and core data across the GoP continental shelf that complemented onshore and offshore research in the region. CHIRP seismic data imaged three Holocene sedimentary lobes. The older Central lobe is downlapped by two younger lobes to the north and south. Sediment analysis showed that the older Central lobe has an elemental signature similar to the younger Northern lobe with both sourced from the Purari River watershed and lobe migration appears to be climatically controlled. The Southern lobe has elemental signatures more consistent with the Fly River watershed. Our results suggest the northern rivers began depositing sediments on the shelf during the Holocene sea level rise in the central region of the GoP and migrated abruptly north at ~2 kybp. Conversely, during the early Holocene transgression, sediments in the Fly drainage system were sequestered onshore infilling accommodation created in the large low-relief coastal plain during the sea level rise. Upon infilling the onshore accommodation, the Fly River delivered sediment to the ocean and formed the Southern lobe. Such differences in onshore storage capacity may introduce a lag between low-gradient rivers (Type I) with a large coastal plain versus high-gradient river systems (Type II) with small coastal plains. The second study site is in the sediment-starved Oceanside Littoral Cell (OCL) of

  4. The role of sediment accumulation on lowland floodplains in modulating sediment discharge and recycling

    NASA Astrophysics Data System (ADS)

    Aalto, R.

    2006-12-01

    I will summarize recent advances in techniques used to study floodplain accumulation rates, dates, and processes in lowland rivers and resulting empirical discoveries regarding the trapping and recycling rates by floodplains within mobile, sand-bedded river-floodplain systems. I will then briefly compare and contrast processes in pristine versus anthropogenically perturbed rivers spanning various tectonic settings. The studied pristine rivers are: 1) the Strickland R. of Papua New Guinea, which traverses a drowned valley basin with both a high sediment discharge and a steep slope, 2) the Fly R. of PNG, which traverses a similar basin with a lower sediment load and slope, 3) the Beni R. of Bolivia, which traverses an enormous foreland basin with a very high sediment load and slope, and 4) the Mamore R. of Bolivia, traversing a similar basin with a lower sediment discharge and slope. Processes of sediment transport, deposition, and recycling differ between these basins, due to differences in slope, sediment and water supply, local hydrology, basin geometry, and tectonic activity. However, in all cases the rates of these processes and the resulting modulation of sediment delivery downstream by large, natural, lowland floodplains are significant, especially when compared to rates in human-influenced floodplains. The human-perturbed rivers discussed are 1) the Sacramento R. of California (USA), which has a moderate sediment load and slope, but is heavily engineered for channel stability and flood control along most of its lowland floodplains, and 2) the Danube R. of Romania, a large river that is also highly engineered, but with more separation between its levees. These engineered floodplains have largely ceased to function as depocenters that both capture and recycle a significant portion of the total sediment load, although the degree of this effect varies with the spacing of the engineered levees. For the natural systems, the floodplains essentially buffer extreme

  5. Sediment source fingerprinting to quantify fine sediment sources in forested catchments, Chile.

    NASA Astrophysics Data System (ADS)

    Schuller, P.; Walling, D. E.; Iroume, A.; Castillo, A.; Quilodran, C.

    2012-04-01

    A study to improve the understanding of the primary sediment sources and transfer pathways in catchments disturbed following forest plantation harvesting is being undertaken in South-Central Chile. The study focuses on two sets of paired experimental catchments (treatment and control), located about 400 km apart, with similar soil type but contrasting mean annual rainfall: Nacimiento (1,200 mm year-1) and Los Ulmos (2,500 mm year-1). Sediment source fingerprinting techniques are being used to document the primary fine sediment sources. In each catchment, three potential sediment sources were defined: clearcut slopes (Z1), forest roads (Z2) and the stream channel (Z3). In each catchment, multiple representative composite samples of the different potential source materials were collected before harvest operations from the upper 1 cm layer in Z1, Z2, and from the channel bank and bed for Z3. A time-integrating trap sampler installed in the discharge monitoring station constructed at the outlet of each catchment has been used to collect samples of the suspended sediment and these have been supplemented by sediment collected from the weir pools. Total suspended sediment load is been quantified in the monitoring stations using discharge records and integrated water sampling. Caesium-137 (137Cs), excess lead-210 (210Pbex) and other sediment properties are being used as fingerprints. After air-drying, oven-drying at 40°C and disaggregation, both the source material samples and the sediment samples collected in the discharge monitoring stations were sieved through a 63-μm sieve and the <63-μm fractions were used for subsequent analyses. For radionuclide assay, the samples were sealed in Petri dishes and after 4 weeks the mass activity density (activity concentration) of 137Cs and 210Pbex was determined by gamma analysis, using an ORTEC extended range Ge detector of 53% relative efficiency. The 137Cs and 210Pbex activity and organic carbon (Corg) concentration associated

  6. Comparison of Erosion Rates Estimated by Sediment Budget Techniques and Suspended Sediment Monitoring and Regulatory Implications

    NASA Astrophysics Data System (ADS)

    O'Connor, M.; Eads, R.

    2007-12-01

    Watersheds in the northern California Coast Range have been designated as "impaired" with respect to water quality because of excessive sediment loads and/or high water temperature. Sediment budget techniques have typically been used by regulatory authorities to estimate current erosion rates and to develop targets for future desired erosion rates. This study examines erosion rates estimated by various methods for portions of the Gualala River watershed, designated as having water quality impaired by sediment under provisions of the Clean Water Act Section 303(d), located in northwest Sonoma County (~90 miles north of San Francisco). The watershed is underlain by Jurassic age sedimentary and meta-sedimentary rocks of the Franciscan formation. The San Andreas Fault passes through the western edge of watershed, and other active faults are present. A substantial portion of the watershed is mantled by rock slides and earth flows, many of which are considered dormant. The Coast Range is geologically young, and rapid rates of uplift are believed to have contributed to high erosion rates. This study compares quantitative erosion rate estimates developed at different spatial and temporal scales. It is motivated by a proposed vineyard development project in the watershed, and the need to document conditions in the project area, assess project environmental impacts and meet regulatory requirements pertaining to water quality. Erosion rate estimates were previously developed using sediment budget techniques for relatively large drainage areas (~100 to 1,000 km2) by the North Coast Regional Water Quality Control Board and US EPA and by the California Geological Survey. In this study, similar sediment budget techniques were used for smaller watersheds (~3 to 8 km2), and were supplemented by a suspended sediment monitoring program utilizing Turbidity Threshold Sampling techniques (as described in a companion study in this session). The duration of the monitoring program to date

  7. Improved understanding of Diatom stratigraphy in a varved sediment through lake monitoring and sediment trap data

    NASA Astrophysics Data System (ADS)

    Maier, Dominique Beatrice; Bigler, Christian

    2016-04-01

    Biological remains in lake sediments reflect past conditions in the lake itself and within its catchment. However, it is difficult to disentangle to which extent the environmental drivers are natural (e.g. population dynamics, climate) or human-induced (e.g. agriculture, forestry). Therefore, comprehensive lake monitoring is crucial to understand taphonomy and sediment formation, and enhances the value of the paleolimnological archive. In this study, we analyze survey data of a varved lake in northern Sweden (Nylandssjön, Nordingrå) with special focus on the diatom record. Different monitoring components are combined, i.e. (1) bi-weekly data of chemical parameters (chlorophyll a, nutrients) covering the period from 2012 to 2015, (2) physical parameters (temperature, oxygen, ice-cover) covering the period from 2000-2015, (3) high-resolution data from a sequential sediment trap covering the period from 2000-2015 and (4) annually resolved diatom data from the sediment varves. Early and intense spring mixing in 2012 translates into a short but vertically pervasive chlorophyll a band which is simultaneously recorded in the sequential trap with a high diatom peak (500 000 valves cm2 d-1). The years 2013 and 2014 show higher chlorophyll a concentrations in the water column, but diatoms do not form a peak flux (>100 000 diatoms cm2 d-1) at any time in the sediment trap, probably due to stratification patterns. The trap record from 2012 indicates a spring bloom dominating the sediment signal, but this is not repeated in 2013 and 2014. Future analyses will be directed towards linking the monitored in-lake processes to annually or even seasonally resolved environmental characteristics. The multiplicity of potential ecological and environmental drivers led us to reverse our analytical view by starting with the diatom stratigraphy in the varved sediment, continuing through the data from sediment trap and water column into the lake catchment to identify deviations (timing

  8. In Situ Sediment Treatment Using Activated Carbon: A Demonstrated Sediment Cleanup Technology

    PubMed Central

    Patmont, Clayton R; Ghosh, Upal; LaRosa, Paul; Menzie, Charles A; Luthy, Richard G; Greenberg, Marc S; Cornelissen, Gerard; Eek, Espen; Collins, John; Hull, John; Hjartland, Tore; Glaza, Edward; Bleiler, John; Quadrini, James

    2015-01-01

    This paper reviews general approaches for applying activated carbon (AC) amendments as an in situ sediment treatment remedy. In situ sediment treatment involves targeted placement of amendments using installation options that fall into two general approaches: 1) directly applying a thin layer of amendments (which potentially incorporates weighting or binding materials) to surface sediment, with or without initial mixing; and 2) incorporating amendments into a premixed, blended cover material of clean sand or sediment, which is also applied to the sediment surface. Over the past decade, pilot- or full-scale field sediment treatment projects using AC—globally recognized as one of the most effective sorbents for organic contaminants—were completed or were underway at more than 25 field sites in the United States, Norway, and the Netherlands. Collectively, these field projects (along with numerous laboratory experiments) have demonstrated the efficacy of AC for in situ treatment in a range of contaminated sediment conditions. Results from experimental studies and field applications indicate that in situ sequestration and immobilization treatment of hydrophobic organic compounds using either installation approach can reduce porewater concentrations and biouptake significantly, often becoming more effective over time due to progressive mass transfer. Certain conditions, such as use in unstable sediment environments, should be taken into account to maximize AC effectiveness over long time periods. In situ treatment is generally less disruptive and less expensive than traditional sediment cleanup technologies such as dredging or isolation capping. Proper site-specific balancing of the potential benefits, risks, ecological effects, and costs of in situ treatment technologies (in this case, AC) relative to other sediment cleanup technologies is important to successful full-scale field application. Extensive experimental studies and field trials have shown that when

  9. Sedimentation and mixing rates of radionuclides in Barents Sea sediments off Novaya Zemlya

    NASA Astrophysics Data System (ADS)

    Smith, J. N.; Ellis, K. M.; Naes, K.; Dahle, S.; Matishov, D.

    Radionuclide measurements have been conducted on sediment cores collected in 1992 in the south-eastern region of the Barents Sea, known as the Pechora Sea. Cesium-137 and 239,24OPu activities in surface sediments are generally less than 30 Bq/kg, with the highest levels being measured in sediments off the southwestern coastline of the island of Novaya Zemlya. High correlations between both 137Cs and 239,24OPu and the concentration of fine (< 63 μm) particles in surface sediments indicate that much of the variance in radionuclide concentrations throughout the Pechora Sea can be explained by particle size fractionation. However, elevated activities of 137Cs (138 Bq/kg), 60Co (92 Bq/kg), 241Am (433 Bq/kg), and especially 239,24OPu (8.47 × 103 Bq/kg) were measured in one surface sediment sample from the fjord of Chernaya Bay on the southern coast of Novaya Zemlya. The source of radioactive contamination is two underwater nuclear tests conducted in Chernaya Bay in 1955 and 1957. The 238Pu /239,240Vu activity ratio of 0.0245 in Chernaya Bay is equivalent to values measured in global fallout. The 240Pu /239Pu atom ratio (0.0304), measured by mass spectrometry, is much lower than values (0.18) typical of global fallout, but is consistent with ratios measured for fallout from the early (1951-1955) series of weapons tests at the Nevada Test Site. The timing of the Chernaya Bay source term, estimated from the 241Am /241Pu ratio, is consistent with the timing of the 1955 and 1957 underwater nuclear tests. Relatively low initial yields of 241Pu ( 241Pu /239Pu atom ratio = 0.00 123) in these tests have resulted in relatively low 241Am /239,240Pu activity ratios (0.05) in recent sediments in Chernaya Bay. Radionuclide tracer profiles in cores from the Pechora Sea can be simulated using a two-layer biodiffusion model with rapid, near-homogeneous mixing in the surface mixed layer and reduced mixing in the deep layer. Lead-210 profiles are consistent with a wide range of

  10. Computations of total sediment discharge, Niobrara River near Cody, Nebraska

    USGS Publications Warehouse

    Colby, Bruce R.; Hembree, C.H.

    1955-01-01

    A natural chute in the Niobrara River near Cody, Nebr., constricts the flow of the river except at high stages to a narrow channel in which the turbulence is sufficient to suspend nearly the total sediment discharge. Because much of the flow originates in the sandhills area of Nebraska, the water discharge and sediment discharge are relatively uniform. Sediment discharges based on depth-integrated samples at a contracted section in the chute and on streamflow records at a recording gage about 1,900 feet upstream are available for the period from April 1948 to September 1953 but are not given directly as continuous records in this report. Sediment measurements have been made periodically near the gage and at other nearby relatively unconfined sections of the stream for comparison with measurements at the contracted section. Sediment discharge at these relatively unconfined sections was computed from formulas for comparison with measured sediment discharges at the contracted section. A form of the Du Boys formula gave computed tonnages of sediment that were unsatisfactory. Sediment discharges as computed from the Schoklitsch formula agreed well with measured sediment discharges that were low, but they were much too low at measured sediment discharges that were higher. The Straub formula gave computed discharges, presumably of bed material, that were several times larger than measured discharges of sediment coarser than 0.125 millimeter. All three of these formulas gave computed sediment discharges that increased with water discharges much less rapidly than the measured discharges of sediment coarser than 0.125 millimeter. The Einstein procedure when applied to a reach that included 10 defined cross sections gave much better agreement between computed sediment discharge and measured sediment discharge than did anyone of the three other formulas that were used. This procedure does not compute the discharge of sediment that is too small to be found in the stream bed in

  11. Habitat heterogeneity reflected in mesophotic reef sediments

    NASA Astrophysics Data System (ADS)

    Weinstein, D. K.; Klaus, J. S.; Smith, T. B.

    2015-11-01

    Modern reef sediments reflect the physical and chemical characteristics of the environment as well as the local reef fauna. Analysis of sedimentary reef facies can thus provide a powerful tool in interpreting ancient reef deposits. However, few studies have attempted to differentiate sedimentary facies in mesophotic coral ecosystems, low light habitats defined as residing 30-150 m below sea level. The low-angle shelf mesophotic coral ecosystem south of the northern U.S. Virgin Islands (USVI) consists of reefs with different structural characteristics ideal for studying the relationship between habitat variability and sedimentary facies. Textural, compositional, and geochemical analyses of surface sediments were used to identify mesophotic reef subfacies associated with distinct benthic communities and structural habitats. Sediment grain composition and bulk geochemistry were found to broadly record the distribution and abundance of coral and macroalgae communities, foundational mesophotic reef benthic organisms. Overall, sediment composition was found to be a good indicator of specific reef environments in low-angle mesophotic reef habitats. Sedimentological analyses indicate that hydrodynamic forces do not transport a significant amount of allochthonous sediment or potentially harmful terrigenous material to USVI mesophotic reefs. Episodic, maximum current velocities prevented deposition of most silt-size grains and smaller, but biological processes were found to have a greater influence on subfacies partitioning than hydrodynamic processes. Results provide a new analog for studies of ancient mesophotic coral ecosystem geological history and document the relationship between mesophotic reef subfacies, structural complexity, and habitat heterogeneity. They also demonstrate how mesophotic reefs along the same shelf system do not always share similar sedimentary characteristics and thus record a diverse set of ecological and environmental conditions.

  12. Indices of benthic community tolerance in contaminated Great Lakes sediments: Relations with sediment contaminant concentrations, sediment toxicity, and the sediment quality triad

    USGS Publications Warehouse

    Wildhaber, M.L.; Schmitt, C.J.

    1998-01-01

    We evaluated the toxic-units model developed by Wildhaber and Schmitt (1996) as a predictor of indices of mean tolerance to pollution (i.e., Lenat, 1993; Hilsenhoff, 1987) and other benthic community indices from Great Lakes sediments containing complex mixtures of environmental contaminants (e.g., polychlorinated biphenyls - PCBs, polycyclic aromatic hydrocarbons PAHs, pesticides, chlorinated dioxins, and metals). Sediment toxic units were defined as the ratio of the estimated pore-water concentration of a contaminant to its chronic toxicity as estimated by U.S. Environmental Protection Agency Ambient Water Quality Criteria (AWQC) or other applicable standard. The total hazard of a sediment to aquatic life was assessed by summing toxic units for all contaminants quantified. Among the benthic community metrics evaluated, total toxic units were most closely correlated with Lenat's (1993) and Hilsenhoff's (1987) indices of community tolerance (T(L), and T(H), respectively); toxic units accounted for 42% (T(L)) and 53% (T(H)) of variability in community tolerance as measured by Ponar grabs. In contrast, taxonomic richness and Shannon-Wiener diversity were not correlated (P > 0.05) with toxic units. Substitution of order- or family-level identifications for lowest possible (mostly genus- or species-) level identifications in the calculation of T(L) and T(H) indices weakened the relationships with toxic units. Tolerance values based on order- and family-level identifications of benthos for artificial substrate samples were more strongly correlated with toxic units than tolerance values for benthos from Ponar grabs. The ability of the toxic-units model to predict the other two components (i.e., laboratory-measured sediment toxicity and benthic community composition) of the Sediment Quality Triad (SQT) may obviate the need for the SQT in some situations.

  13. Sediment Distribution on Skeidararsandur, Southeast Iceland.

    NASA Astrophysics Data System (ADS)

    Gomez, B.; Russell, A. J.; Finnegan, D. C.; Smith, L. C.; Knudsen, O.

    2001-12-01

    The zone of outwash accumulation is perhaps the most distinctive feature of the proglacial environment. Its gross morphology is determined by the topography of the proglacial zone, the volume of the sediment input, and the processes responsible for sediment distribution. The largest unconfined, active outwash plain on Earth, Skeidararsandur, extends seawards across the coastal plain of southeastern Iceland. Investigations of the proximal surface of Skeidararsandur using a variety of data sources, including Landsat Thematic Mapper imagery, Synthetic Aperture Radar data, Airborne Topographic Mapper laser altimeter data and high-resolution aerial photography, have provided a synoptic perspective of the proglacial drainage system. Over the past 50 yr Skeidararjokull has become decoupled from the sandur and the original, highly diffuse, multipoint distubutary system, inactive remnants of which are preserved on the sandur's proximal surface, has been transformed into an integrated drainage network, with only three primary outlets. These entrenched channels constrain jokulhlaups and ablation dominated flows alike, and permit most meltwater to bypass the proximal surface. The shift from a diffuse to a channelized (point source) distributary system has had a significant impact on the magnitude and style of sedimentation throughout the proximal zone, and also on the size of sediment supplied to the sandur. Stratigraphic evidence suggests both jokulhlaups and glacier surges have a significant influence on the development of the fluvial succession in the proximal zone, but a diffuse, multipoint distributary system is required to sustain active accretion across the sandur as a whole. The contemporary meltwater distributary system on Skeidararsandur, which is a product of glacier retreat, may thus represent one end of the spectrum of channel configurations that facilitate sediment distribution on sandar.

  14. Karst is a repository for old sediments

    SciTech Connect

    Hobbs, H.C. )

    1994-04-01

    The Paleozoic plateau of southeastern Minnesota has been repeatedly glaciated, and has accumulated several sheets of loess. In the eastern part of this area, most of the older sediments have been eroded away and the late Wisconsinan Peoria loess directly overlies limestone. A lag of erratics from one or more older tills occurs sporadically on the bedrock surface. A more complete record is preserved in some sinkholes and solution cavities. Sinkholes (surface depressions) contain material that washed or collapsed into the hole, as well as material that was deposited directly (such as loess). Solution cavities contain only material sorted by water. Sinkhole fills exposed in roadcuts and quarry walls commonly lack the surface expression and black-dirt funnel'' of active sinkholes. Several of these contain erratic-bearing sediment interpreted as slopewash and mudflow. One appears to contain actual till--unsorted, unbedded pebble-loam that is not mixed with other materials commonly found on the limestone surface, such as red clay or loess. It cannot be determined whether this material was deposited directly or collapsed in later. Solution cavities are typically packed with sediment right up to the top. The bulk of such deposits is typically clay and silt; however, erratic pebbles are present in some. The fine sediment is sorted and bedded, at least in places. In one large cavity fill, a layer of rip-up clay clasts occurs near the top. Study of the stratigraphy of karst sediments in southeastern Minnesota is still preliminary. Techniques which are used to correlate them include: physical characteristics, texture analysis (on material that has not been sorted), sand and pebble lithology, and magnetic polarity. Techniques that could be used include clay mineralogy, geochemical analysis, and thermoluminescence.

  15. River sediment flux and shelf sediment accumulation rates on the Pacific Northwest margin

    NASA Astrophysics Data System (ADS)

    Wheatcroft, R. A.; Sommerfield, C. K.

    2005-02-01

    To test the generality of insight obtained from recent STRATAFORM studies of northern California's Eel margin, river sediment sources and continental shelf sinks were examined on the Pacific Northwest margin from 38° to 44.5°N. River discharge and sediment concentration data acquired by the US Geological Survey were used to update long-term annual suspended-sediment loads for 17 rivers that range in basin area from 635 to ˜22,000 km 2. Resulting annual load estimates vary over 3 orders of magnitude (0.065-18×10 9 kg/yr), with major suspended-sediment fluxes supplied by, in decreasing order, the Eel, Klamath/Trinity, Mad, Rogue, Umpqua and Russian rivers. Down-core profiles of excess 210Pb and 137Cs were used to estimate sediment accumulation rates (SARs) at prescribed depths (70 and 110 m) and distances (0-40-km north and south along-shelf) from each of the major rivers. SARs were found to vary much less than the river flux estimates, and are mostly in the range of 1.5 to 6 mm/yr. Most significantly, shelf SARs on the other Pacific Northwest margins are only slightly less than those observed on the Eel shelf, implying that much higher proportions of riverine sediment are retained on those shelves. Likely reasons that the Eel dispersal system exhibits greater off-shelf transport are (1) the narrower and steeper shelf geometry, and (2) the existence of a newly documented cross-isobath sediment transport mechanism that involves wave-modulated fluid mud flows. Testing whether the fluid mud flows are a consequence of the Eel River basin's high sediment yield, and are thus unique to the Eel, or are caused by intense wave energy during discharge events, and hence are operative on many other margins, awaits future bottom-boundary layer measurements.

  16. Microbioirrigation of marine sediments in dysoxic environments: Implications for early sediment fabric formation and diagenetic processes

    NASA Astrophysics Data System (ADS)

    Pike, Jennifer; Bernhard, Joan M.; Moreton, Steven G.; Butler, Ian B.

    2001-10-01

    It is manifest in the study of dysoxic sediments from the geological record that infaunal burrowing is considered so severely limited by the lack of dissolved oxygen as to be nonexistent. Although the effects of megafauna and macrofauna on sedimentary and geochemical processes are well known, the effects of meiofauna are largely ignored. Here we document abundant meiofauna in the recent severely dysoxic, laminated sediments from the Santa Barbara basin, California margin, and also microcavities and microtunnels in laminated deglacial sediments from Palmer Deep, west Antarctic Peninsula, that we interpret to be open, relict nematode burrows. Santa Barbara basin box-core subcores were sieved to quantify metazoan abundance, and others were embedded with resin for examination of meiofaunal life positions using confocal microscopy. Metazoan densities in the surface centimeters of sediment range from 80.7 to 117.9 cm-3, and nematode populations, together with their abundant burrows, remain quite high to at least 3 cm. Scanning electron microscope analysis of fractured surfaces in Palmer Deep sediments revealed that the rigid diatom ooze framework aids the preservation of ˜50 μm diameter open nematode burrows. These structures were observed to at least 40 m below the seafloor surface. This is the first description of a nematode-produced open burrow network preserved in the geological record. Optical microscopy of resin-embedded thin sections revealed widespread sediment redistribution without significant lamina disruption. The implications of abundant nematode burrows in surface sediments, and their preservation in the geological record, are wide ranging for both modern and ancient dysoxic marine environments, including for determining early sediment fabric production, geochemical processes, and diagenetic reactions in the oxic and suboxic zones.

  17. Commercially available control sediment for use in Hyalella azteca whole sediment toxicity testing

    SciTech Connect

    Smith, M.E.; Herrin, L.E.; Lazorchak, J.M.

    1995-12-31

    A commercially available potting soil was used as a control sediment in 7 and 10 day Hyalella azteca whole sediment tests. Results show the potting soil sediment (PSS) provides better growth for H. azteca than an artificial sediment (AS). This was believed to be due to an overall increase in the organic content of the potting soil versus the artificial sediment. In side by side tests lasting 7 days, the mean survival of the H. azteca in PSS ranged from 90% to 99% and mean dry weights ranging from 0.104 to 0.129 mg/organism. Mean survival in the AS ranged from 90% to 99% with mean dry weights ranging from 0.039 to 0.097 mg/organism. Tests conducted with natural sediment at this same time resulted in mean survival ranging from 80% to 99%, with mean dry weights ranging from 0.075 to 0.111 mg/organism. In 10 day control tests with PSS and AS, mean survival of the H. azteca in PSS ranged from 83% to 100% with mean dry weights ranging from 0.164 to 0.218 mg/organism. H. azteca tested in AS over this same time period had mean survival ranging from 89% to 100% with mean dry weights ranging from 0.097 to 0.138 mg/organism. The authors conclude that commercially available potting soil will provide a source for a consistent control sediment, with growth, measured as mean dry weight, that more closely approximates many non-contaminated natural sediments.

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

    PubMed Central

    Lenstra, Wytze; Jong, Dirk; Meysman, Filip J. R.; Sapart, Célia J.; van der Veen, Carina; Röckmann, Thomas; Gonzalez, Santiago; Slomp, Caroline P.

    2016-01-01

    Globally, the methane (CH4) efflux from the ocean to the atmosphere is small, despite high rates of CH4 production in continental shelf and slope environments. This low efflux results from the biological removal of CH4 through anaerobic oxidation with sulfate in marine sediments. In some settings, however, pore water CH4 is found throughout the sulfate-bearing zone, indicating an apparently inefficient oxidation barrier for CH4. Here we demonstrate that rapid sediment accumulation can explain this limited capacity for CH4 removal in coastal sediments. In a saline coastal reservoir (Lake Grevelingen, The Netherlands), we observed high diffusive CH4 effluxes from the sediment into the overlying water column (0.2–0.8 mol m-2 yr-1) during multiple years. Linear pore water CH4 profiles and the absence of an isotopic enrichment commonly associated with CH4 oxidation in a zone with high rates of sulfate reduction (50–170 nmol cm-3 d-1) both suggest that CH4 is bypassing the zone of sulfate reduction. We propose that the rapid sediment accumulation at this site (~ 13 cm yr-1) reduces the residence time of the CH4 oxidizing microorganisms in the sulfate/methane transition zone (< 5 years), thus making it difficult for these slow growing methanotrophic communities to build-up sufficient biomass to efficiently remove pore water CH4. In addition, our results indicate that the high input of organic matter (~ 91 mol C m-2 yr-1) allows for the co-occurrence of different dissimilatory respiration processes, such as (acetotrophic) methanogenesis and sulfate reduction in the surface sediments by providing abundant substrate. We conclude that anthropogenic eutrophication and rapid sediment accumulation likely increase the release of CH4 from coastal sediments. PMID:27560511

  19. LITERATURE REVIEW AND REPORT: SURFACE-SEDIMENT SAMPLER DATABASE

    EPA Science Inventory

    A literature review was conducted to identify available surface sediment sampling technologies with an ability to collect undisturbed sediments to depths of up to 1 meter below the water sediment interface. This survey was conducted using published literature and references, Envi...

  20. ASSESSING STREAM BED STABILITY AND EXCESS SEDIMENTATION IN MOUNTAIN STREAMS

    EPA Science Inventory

    Land use and resource exploitation in headwaters catchments?such as logging, mining, and road building?often increase sediment supply to streams, potentially causing excess sedimentation. Decreases in mean substrate size and increases in fine stream bed sediments can lead to inc...

  1. A FIELD VALIDATION OF TWO SEDIMENT-AMPHIPOD TOXICITY TESTS

    EPA Science Inventory

    A field validation study of two sediment-amphipod toxicity tests was conducted using sediment samples collected subtidally in the vicinity of a polycyclic aromatic hydrocarbon (PAH)-contaminated Superfund site in Elliott Bay, WA, USA. Sediment samples were collected at 30 stati...

  2. 30 CFR 817.45 - Hydrologic balance: Sediment control measures.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... limitations, (3) Minimize erosion to the extent possible. (b) Sediment control measures include practices... reclamation techniques are applied to reduce erosion and control sediment. Sediment control measures consist... protected channels or pipes through disturbed areas so as not to cause additional erosion; (6) Using...

  3. 30 CFR 816.45 - Hydrologic balance: Sediment control measures.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... limitations, (3) Minimize erosion to the extent possible. (b) Sediment control measures include practices... reclamation techniques are applied to reduce erosion and control sediment. Sediment control measures consist... protected channels or pipes through disturbed areas so as not to cause additional erosion; (6) Using...

  4. 30 CFR 817.45 - Hydrologic balance: Sediment control measures.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... limitations, (3) Minimize erosion to the extent possible. (b) Sediment control measures include practices... reclamation techniques are applied to reduce erosion and control sediment. Sediment control measures consist... protected channels or pipes through disturbed areas so as not to cause additional erosion; (6) Using...

  5. 30 CFR 817.45 - Hydrologic balance: Sediment control measures.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... limitations, (3) Minimize erosion to the extent possible. (b) Sediment control measures include practices... reclamation techniques are applied to reduce erosion and control sediment. Sediment control measures consist... protected channels or pipes through disturbed areas so as not to cause additional erosion; (6) Using...

  6. 30 CFR 817.45 - Hydrologic balance: Sediment control measures.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... limitations, (3) Minimize erosion to the extent possible. (b) Sediment control measures include practices... reclamation techniques are applied to reduce erosion and control sediment. Sediment control measures consist... protected channels or pipes through disturbed areas so as not to cause additional erosion; (6) Using...

  7. 30 CFR 816.45 - Hydrologic balance: Sediment control measures.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... limitations, (3) Minimize erosion to the extent possible. (b) Sediment control measures include practices... reclamation techniques are applied to reduce erosion and control sediment. Sediment control measures consist... protected channels or pipes through disturbed areas so as not to cause additional erosion; (6) Using...

  8. 30 CFR 816.45 - Hydrologic balance: Sediment control measures.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... limitations, (3) Minimize erosion to the extent possible. (b) Sediment control measures include practices... reclamation techniques are applied to reduce erosion and control sediment. Sediment control measures consist... protected channels or pipes through disturbed areas so as not to cause additional erosion; (6) Using...

  9. 30 CFR 817.45 - Hydrologic balance: Sediment control measures.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... limitations, (3) Minimize erosion to the extent possible. (b) Sediment control measures include practices... reclamation techniques are applied to reduce erosion and control sediment. Sediment control measures consist... protected channels or pipes through disturbed areas so as not to cause additional erosion; (6) Using...

  10. 30 CFR 816.45 - Hydrologic balance: Sediment control measures.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... limitations, (3) Minimize erosion to the extent possible. (b) Sediment control measures include practices... reclamation techniques are applied to reduce erosion and control sediment. Sediment control measures consist... protected channels or pipes through disturbed areas so as not to cause additional erosion; (6) Using...

  11. 30 CFR 816.45 - Hydrologic balance: Sediment control measures.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... limitations, (3) Minimize erosion to the extent possible. (b) Sediment control measures include practices... reclamation techniques are applied to reduce erosion and control sediment. Sediment control measures consist... protected channels or pipes through disturbed areas so as not to cause additional erosion; (6) Using...

  12. Riparian Sediment Delivery Ratio: Stiff Diagrams and Artifical Neural Networks

    EPA Science Inventory

    Various methods are used to estimate sediment transport through riparian buffers and grass jilters with the sediment delivery ratio having been the most widely applied. The U.S. Forest Service developed a sediment delivery ratio using the stiff diagram and a logistic curve to int...

  13. Carbon enrichment in windblown sediment on the Columbia Plateau

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sediment flux into the atmosphere from agricultural soils during high wind events can impact resource management and the environment. For example, nutrients in the sediment represent a loss of fertilizer from soils that must be replenished for sustained crop production. In addition, sediments that a...

  14. Ultrasonic interferometry: study of particle sedimentation in liquid.

    PubMed

    Razavian, S M; Boynard, M; Guillet, R; Bertholom, P; Beuzard, Y

    1991-08-01

    An ultrasonic interferometry method was designed to study sedimentation of particles in liquid. The method, based on A mode echography, measures the amplitude of ultrasonic waves reflected (echo E1) by a fixed interface I1 called "solid plate-sediment" interface formed when particles are sedimenting on a solid plate. The amplitude of the echo depends both on mechanical properties of the three media (solid plate, sediment and suspension) on the thickness of the sediment and on the presence of a second mobile interface I2 called "sediment-suspension" interface. In the first phase of sedimentation when the second interface is very close to the first, two reflected waves interfere. Then, in the second phase of sedimentation when the sediment is thick enough, the amplitude of the echo E1 depends only on the sediment and solid plate properties. The first phase will give information on the sedimentation rate of particles (SR). We have compared SR of particles determined by this method with SR measured in a cylindrical tube of the same geometry as the ultrasonic measurement cell and with theoretical values of the sedimentation rate given by theoretical models.

  15. Lead Speciation And Bioavailability In Apatite-Amended Sediments

    EPA Science Inventory

    The in situ sequestration of lead (Pb) in sediment with a phosphate amendment was investigated by Pb speciation and bioavailability. Sediment Pb in preamendment samples was identified as galena (PbS) with trace amounts of absorbed Pb. Sediment exposed to atmospheric conditions ...

  16. A Manual to Identify Sources of Fluvial Sediment | Science ...

    EPA Pesticide Factsheets

    Sedimentation is one of the main causes of stream/river aquatic life use impairments in R3. Currently states lack standard guidance on appropriate tools available to quantify sediment sources and develop sediment budgets in TMDL Development. Methods for distinguishing sediment types for TMDL development will focus stream restoration and soil conservation efforts in strategic locations in a watershed and may better target appropriate BMPs to achieve sediment load reductions. Properly identifying sediment sources in a TMDL will also help focus NPDES permitting, stream restoration activities and other TMDL implementation efforts. This project will focus on developing a framework that will be published as a guidance document that outlines steps and approaches to identify the significant sources of fine-grained sediment in 303D listed watersheds. In this framework, the sediment-fingerprinting and sediment budget approaches will be emphasized. This project will focus on developing a framework that will be published as a guidance document that outlines steps and approaches to identify the significant sources of fine-grained sediment in 303D listed watersheds. In this framework, the sediment-fingerprinting and sediment budget approaches will be emphasized.

  17. Sediment Bioaccumulation Test with Lumbriculus variegatus: Effects of Organism Loading

    EPA Science Inventory

    Sediment bioaccumulation tests with Lumbriculus variegatus were performed on seven sediments with a series of ratios of total organic carbon in sediment to L. variegatus (dry weight) (TOC/Lv) that spanned the recommendation of no less than 50:1. With increasing loading of organi...

  18. Sequestration of nonylphenol in sediment from Bohai Bay, North China.

    PubMed

    Jin, Fen; Hu, Jianying; Liu, Jinlin; Yang, Min; Wang, Fu; Wang, Hong

    2008-02-01

    The ubiquity of nonylphenol (NP) in aquatic environments has been well documented, and the long-term fate of NP in sediments is a concern from the viewpoint of risk assessment due to its endocrine-disrupting effects. This paper reports on the assessment of long-term fate of NP in marine sediments by determining extractable and nonextractable fractions of NP in surface sediments and a sediment core from Bohai Bay, North China. The extractable fraction was operationally defined as the fraction of NP that was extracted with a solvent mixture of methanol/methylene chloride, and the nonextractable fraction was the portion of NP that can be released from the sediments by alkaline hydrolyzing after the initial solvent extraction. The total concentrations (extractable and nonextractable) of NP were 3.4-34.3 ng/g dw in the surface sediments and 2.2-17.7 ng/g dw in the sediment core. Depending on the sedimentation time, the percentage of nonextractable NP relative to the total NP in the core ranged from 38 to 99%. Based on the relationship between the percentage of nonextractable NP in sediments and sedimentation time, the sequestration rate of NP in the sediment core from Bohai Bay was estimated to be 0.94% x a(-1). These results have important implications in understanding the geochemical fate of NP in sediments.

  19. SEDIMENTS: A RESERVOIR OF HISTORIC CONTAMINATION OF THE ENVIRONMENT

    EPA Science Inventory

    Sediments contain contaminants derived from past activities that seriously degraded the environment.

    During low water, sediments are subject to natural erosion or removal for navigation.

    Erosion or dredging of sediment will release contaminants into the environment ...

  20. Sediment tracers in water erosion studies: Current approaches and challenges

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The interest in the use of sediment tracers as a complementary tool to traditional water soil erosion or deposition measurements or assessment has increased due to the additional information they may provide such as sediment source identification and tracking of sediment movement over the landscape ...

  1. Incorporating Contaminant Bioavailability into Sediment Quality Assessment Frameworks

    EPA Science Inventory

    The recently adopted sediment quality assessment framework for evaluating bay and estuarine sediments in the State of California incorporates bulk sediment chemistry as a key line of evidence(LOE) but does not address the bioavailability of measured contaminants. Thus, the chemis...

  2. Sediment source determination using fallout Cesium-137 in arid rangelands.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sediment source identification in arid rangelands is necessary to understanding rangeland conditions and developing management practices to improve rangeland health and reduce sediment load to streams. The purpose of this research was to use Cesium-137 to identify sources of sediments in an arid ran...

  3. Virginia Erosion and Sediment Control Handbook. Standards, Criteria and Guidelines.

    ERIC Educational Resources Information Center

    Virginia State Soil and Water Conservation Commission, Richmond, VA.

    Guidelines and technical standards for development of local erosion and sediment control programs and conservation standards to meet the goals established by the Virginia Erosion and Sediment Control law are presented in this handbook. Part I defines natural and manmade erosion, sedimentation, and the hazards of uncontrolled wear and damage to the…

  4. Sediment bioaccumulation test with Lumbriculus variegatus: Effects of feeding

    EPA Science Inventory

    Sediment bioaccumulation tests with Lumbriculus variegatus were performed on seven sediments with a series of ratios of total organic carbon in sediment to L. variegatus (dry weight) (TOC/Lv) that spanned the recommendation of no less than 50:1. With increasing loading of organi...

  5. Comparing Laboratory and Field Measured Biota-sediment Accumulation Factors

    EPA Science Inventory

    The report presents a review of studies where biota-sediment accumulation factors (BSAFs) were measured in the field, and the same sediment samples were tested in the laboratory using sediment bioaccumulation testing protocols. The focus of this review was to document the extent...

  6. Effects of Sediment Composition on Growth of Submersed Aquatic Vegetation

    DTIC Science & Technology

    1986-01-01

    weight loss on ignition. Total sediment carbon and Inorganic carbon were determined directly using a Leco carbon analyzer. Humus fractions (fulvic...and huinic acids) were quantified spectrophotometrically following a series of acid-base extractions of wet sediment ( Stevenson 1982). Sediment... Humus fractions (fulvic and humic acids), non- humic organic matter, and total Kjeldahl nitrogen (TKN) were all positively and significantly

  7. DENITRIFICATION AND NITROGEN DYNAMICS IN SEDIMENTS OF A MID-ATLANTIC INCISED STREAM DEPOSITED WITH DEEP LEGACY SEDIMENTS.

    EPA Science Inventory

    Excess legacy sediments deposited in former impounded streams frequently bury Holocene pre-settlement wetlands, decrease in-situ nitrogen removal, and increase nitrogen transport downstream, particularly where deep incised channels limit sediment-water interactions. This has prom...

  8. Bedded Sediment Conditions and Macroinvertebrate Responses in New Mexico Streams: A First Step in Establishing Sediment Criteria

    EPA Science Inventory

    Aquatic life protection was the impetus for a New Mexico Environment Department (NMED) effort to define bedded sediment conditions in streams that were natural and tolerable, especially to benthic macroinvertebrates. Sediments were measured using surveys of streambed particles to...

  9. Effect of sediment size on bioleaching of heavy metals from contaminated sediments of Izmir Inner Bay.

    PubMed

    Guven, Duyusen E; Akinci, Gorkem

    2013-09-01

    The effect of sediment size on metals bioleaching from bay sediments was investigated by using fine (< 45 microm), medium (45-300 microm), and coarse (300-2000 microm) size fractions of a sediment sample contaminated with Cr, Cu, Pb, and Zn. Chemical speciation of the metals in bulk and size fractions of sediment were studied before and after bioleaching. Microbial activity was provided with mixed cultures of Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans. The bioleaching process was carried out in flask experiments for 48 days, by using 5% (W/V) of solid concentration in suspension. Bioleaching was found to be efficient for the removal of selected heavy metals from every size fraction of sediments, where the experiments with the smaller particles resulted in the highest solubilization ratios. At the end of the experimental period, Cr, Cu, Pb and Zn were solubilized to the ratios of 68%, 88%, 72%, and 91% from the fine sediment, respectively. Higher removal efficiencies can be explained by the larger surface area provided by the smaller particles. The changes in the chemical forms of metals were determined and most of the metal releases were observed from the reducible and organic fractions independent from grain size. Higher concentrations were monitored in the residual fraction after bioleaching period, suggesting they are trapped in this fraction, and cannot be solubilized under natural conditions.

  10. The Materosion project, a sediment cascade modeling for torrential sediment transfers: final results and perspectives

    NASA Astrophysics Data System (ADS)

    Rudaz, Benjamin; Loye, Alexandre; Mazotti, Benoit; Bardou, Eric; Jaboyedoff, Michel

    2013-04-01

    The Materosion project, conducted between the swiss canton of Valais (CREALP) and University of Lausanne (CRET) aims at forecasting sediment transfer in alpine torrents using the sediment cascade concept. The study site is the high Anniviers valley, around the village of Zinal (Valais). The torrents are divided in homogeneous reaches, to and from which sediments are transported by debris flows and bedload transport events. The model runs simulations of 100 years, with a 1-month time step, each with a given a random meteorological event ranging from no activity up to high magnitude debris flows. These events are calibrated using local rain data and observed corresponding debris flow frequencies. The model is applied to ten torrent systems with variable geological context, watershed geometries and sediment supplies. Given the high number of possible event scenarios, 10'000 simulations per torrent are performed, giving a statistical distribution of cumulated volumes and an event size distribution. A way to visualize the complex results data is proposed, and a back-analysis of the internal sediment cascade dynamic is performed. The back-analysis shows that the results' distribution stabilize after ~5'000 simulations. The model results, especially the range of debris flow volumes are crucial to maintain mitigation measures such as retention dams, and give clues for future sediment cascade modeling.

  11. Heavy metal concentrations and toxicity in water and sediment from stormwater ponds and sedimentation tanks.

    PubMed

    Karlsson, Kristin; Viklander, Maria; Scholes, Lian; Revitt, Mike

    2010-06-15

    Sedimentation is a widely used technique in structural best management practices to remove pollutants from stormwater. However, concerns have been expressed about the environmental impacts that may be exerted by the trapped pollutants. This study has concentrated on stormwater ponds and sedimentation tanks and reports on the accumulated metal concentrations (Cd, Cr, Ni, Pb, and Zn) and the associated toxicity to the bacteria Vibrio fischeri. The metal concentrations are compared with guidelines and the toxicity results are assessed in relation to samples for which metal concentrations either exceed or conform to these values. The water phase metal concentrations were highest in the ponds whereas the sedimentation tanks exhibited a distinct decrease towards the outlet. However, none of the water samples demonstrated toxicity even though the concentrations of Cu, Pb, and Zn exceeded the threshold values for the compared guidelines. The facilities with higher traffic intensities had elevated sediment concentrations of Cr, Cu, Ni, and Zn which increased towards the outlet for the sedimentation tanks in agreement with the highest percentage of fine particles. The sediments in both treatment facilities exhibited the expected toxic responses in line with their affinity for heavy metals but the role of organic carbon content is highlighted.

  12. Algal Turf Sediments and Sediment Production by Parrotfishes across the Continental Shelf of the Northern Great Barrier Reef

    PubMed Central

    Goatley, Christopher H. R.; Bellwood, David R.

    2017-01-01

    Sediments are found in the epilithic algal matrix (EAM) of all coral reefs and play important roles in ecological processes. Although we have some understanding of patterns of EAM sediments across individual reefs, our knowledge of patterns across broader spatial scales is limited. We used an underwater vacuum sampler to quantify patterns in two of the most ecologically relevant factors of EAM sediments across the Great Barrier Reef: total load and grain size distribution. We compare these patterns with rates of sediment production and reworking by parrotfishes to gain insights into the potential contribution of parrotfishes to EAM sediments. Inner-shelf reef EAMs had the highest sediment loads with a mean of 864.1 g m-2, compared to 126.8 g m-2 and 287.4 g m-2 on mid- and outer-shelf reefs, respectively. High sediment loads were expected on inner-shelf reefs due to their proximity to the mainland, however, terrigenous siliceous sediments only accounted for 13–24% of total mass. On inner-shelf reef crests parrotfishes would take three months to produce the equivalent mass of sediment found in the EAM. On the outer-shelf it would take just three days, suggesting that inner-shelf EAMs are characterised by low rates of sediment turnover. By contrast, on-reef sediment production by parrotfishes is high on outer-shelf crests. However, exposure to oceanic swells means that much of this production is likely to be lost. Hydrodynamic activity also appears to structure sediment patterns at within-reef scales, with coarser sediments (> 250 μm) typifying exposed reef crest EAMs, and finer sediments (< 250 μm) typifying sheltered back-reef EAMs. As both the load and grain size of EAM sediments mediate a number of important ecological processes on coral reefs, the observed sediment gradients are likely to play a key role in the structure and function of the associated coral reef communities. PMID:28122042

  13. Algal Turf Sediments and Sediment Production by Parrotfishes across the Continental Shelf of the Northern Great Barrier Reef.

    PubMed

    Tebbett, Sterling B; Goatley, Christopher H R; Bellwood, David R

    2017-01-01

    Sediments are found in the epilithic algal matrix (EAM) of all coral reefs and play important roles in ecological processes. Although we have some understanding of patterns of EAM sediments across individual reefs, our knowledge of patterns across broader spatial scales is limited. We used an underwater vacuum sampler to quantify patterns in two of the most ecologically relevant factors of EAM sediments across the Great Barrier Reef: total load and grain size distribution. We compare these patterns with rates of sediment production and reworking by parrotfishes to gain insights into the potential contribution of parrotfishes to EAM sediments. Inner-shelf reef EAMs had the highest sediment loads with a mean of 864.1 g m-2, compared to 126.8 g m-2 and 287.4 g m-2 on mid- and outer-shelf reefs, respectively. High sediment loads were expected on inner-shelf reefs due to their proximity to the mainland, however, terrigenous siliceous sediments only accounted for 13-24% of total mass. On inner-shelf reef crests parrotfishes would take three months to produce the equivalent mass of sediment found in the EAM. On the outer-shelf it would take just three days, suggesting that inner-shelf EAMs are characterised by low rates of sediment turnover. By contrast, on-reef sediment production by parrotfishes is high on outer-shelf crests. However, exposure to oceanic swells means that much of this production is likely to be lost. Hydrodynamic activity also appears to structure sediment patterns at within-reef scales, with coarser sediments (> 250 μm) typifying exposed reef crest EAMs, and finer sediments (< 250 μm) typifying sheltered back-reef EAMs. As both the load and grain size of EAM sediments mediate a number of important ecological processes on coral reefs, the observed sediment gradients are likely to play a key role in the structure and function of the associated coral reef communities.

  14. A manual to identify sources of fluvial sediment

    USGS Publications Warehouse

    Gellis, Allen; Fitzpatrick, Faith; Schubauer-Berigan, Joseph

    2017-01-01

    Sediment is an important pollutant of concern that can degrade and alter aquatic habitat. A sediment budget is an accounting of the sources, storage, and export of sediment over a defined spatial and temporal scale. This manual focuses on field approaches to estimate a sediment budget. We also highlight the sediment fingerprinting approach to attribute sediment to different watershed sources. Determining the sources and sinks of sediment is important in developing strategies to reduce sediment loads to water bodies impaired by sediment. Therefore, this manual can be used when developing a sediment TMDL requiring identification of sediment sources.The manual takes the user through the seven necessary steps to construct a sediment budget:Decision-making for watershed scale and time period of interestFamiliarization with the watershed by conducting a literature review, compiling background information and maps relevant to study questions, conducting a reconnaissance of the watershedDeveloping partnerships with landowners and jurisdictionsCharacterization of watershed geomorphic settingDevelopment of a sediment budget designData collectionInterpretation and construction of the sediment budgetGenerating products (maps, reports, and presentations) to communicate findings.Sediment budget construction begins with examining the question(s) being asked and whether a sediment budget is necessary to answer these question(s). If undertaking a sediment budget analysis is a viable option, the next step is to define the spatial scale of the watershed and the time scale needed to answer the question(s). Of course, we understand that monetary constraints play a big role in any decision.Early in the sediment budget development process, we suggest getting to know your watershed by conducting a reconnaissance and meeting with local stakeholders. The reconnaissance aids in understanding the geomorphic setting of the watershed and potential sources of sediment. Identifying the potential

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

    USGS Publications Warehouse

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

    2004-01-01

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

  16. Sediment Supply as a Control on Plant-Morphodynamic Interactions

    NASA Astrophysics Data System (ADS)

    Manners, R.; Wilcox, A. C.; Kui, L.; Stella, J. C.; Lightbody, A.; Sklar, L. S.

    2014-12-01

    The caliber and quantity of sediment delivered to a channel influences its size and shape, yet we know little about how the sediment supply affects rivers whose geomorphic form is influenced by riparian vegetation. We present results from flume experiments that test the impact of sediment supply on plant-morphodynamic interactions. We introduced two sediment supply conditions to a 28-meter long, sand bedded flume (60 cm wide and 71 cm deep) at the UC-Berkeley Richmond Field Station: equilibrium (balance between sediment transport and supply) and deficit (transport exceeds sediment supply). We conducted ten runs with different riparian seedling configurations (individual plants or patches) and species (tamarisk or cottonwood), and stem and leaf density (0.003-0.47 cm2/cm2), under both sediment supply conditions. Plant species, size, and configuration were important in predicting the topographic adjustments that occurred during our experiments. These influences may be attributed to differences in plant morphology; tamarisk is shrubby while cottonwood is more tree-like, with a single stem and leaves concentrated higher on the plant. The plant-morphodynamic relationship, however, differed for the two sediment supply conditions. During sediment equilibrium, only patches of cottonwood served as sediment sinks compared to an unvegetated bed, but tamarisk patches had no impact on the sediment mass balance. During sediment deficit, in contrast, tamarisk patches accumulated more sediment than unvegetated beds. Stem and leaf density also controlled changes in bed elevation. During equilibrium conditions, increasing the density of cottonwood stems and leaves resulted in greater bed degradation. Conversely, aggradation occurred with increases in the density of tamarisk. For sediment deficit conditions, the relationship between stem and leaf density and the rate of bed change was negative for both species (i.e., higher density resulted in faster rate of scour). The shifting

  17. Protecting sediment-sensitive aquatic species inmountain streams through the application of biologically based streambed sediment criteria

    EPA Science Inventory

    We evaluated several lines of evidence to identify bedded fine sediment levels that should protect and maintain self-sustaining populations of native sediment-sensitive aquatic species in the western US. To identify these potential criterion values for streambed sediments ≤0.06 ...

  18. Let's Bet on Sediments! Hudson Canyon Cruise--Grades 9-12. Focus: Sediments of Hudson Canyon.

    ERIC Educational Resources Information Center

    National Oceanic and Atmospheric Administration (DOC), Rockville, MD.

    These activities are designed to teach about the sediments of Hudson Canyon. Students investigate and analyze the patterns of sedimentation in the Hudson Canyon, observe how heavier particles sink faster than finer particles, and learn that submarine landslides are avalanches of sediment in deep ocean canyons. The activity provides learning…

  19. Geomorphic coupling and sediment connectivity in an alpine catchment — Exploring sediment cascades using graph theory

    NASA Astrophysics Data System (ADS)

    Heckmann, Tobias; Schwanghart, Wolfgang

    2013-01-01

    Through their relevance for sediment budgets and the sensitivity of geomorphic systems, geomorphic coupling and (sediment) connectivity represent important topics in geomorphology. Since the introduction of the systems perspective to physical geography by Chorley and Kennedy (1971), a catchment has been perceived as consisting of landscape elements (e.g. landforms, subcatchments) that are coupled by geomorphic processes through sediment transport. In this study, we present a novel application of mathematical graph theory to explore the network structure of coarse sediment pathways in a central alpine catchment. Numerical simulation models for rockfall, debris flows, and (hillslope and channel) fluvial processes are used to establish a spatially explicit graph model of sediment sources, pathways and sinks. The raster cells of a digital elevation model form the nodes of this graph, and simulated sediment trajectories represent the corresponding edges. Model results are validated by visual comparison with the field situation and aerial photos. The interaction of sediment pathways, i.e. where the deposits of a geomorphic process form the sources of another process, forms sediment cascades, represented by paths (a succession of edges) in the graph model. We show how this graph can be used to explore upslope (contributing area) and downslope (source to sink) functional connectivity by analysing its nodes, edges and paths. The analysis of the spatial distribution, composition and frequency of sediment cascades yields information on the relative importance of geomorphic processes and their interaction (however regardless of their transport capacity). In the study area, the analysis stresses the importance of mass movements and their interaction, e.g. the linkage of large rockfall source areas to debris flows that potentially enter the channel network. Moreover, it is shown that only a small percentage of the study area is coupled to the channel network which itself is

  20. Diagenetic regimes in Arctic Ocean sediments: Implications for sediment geochemistry and core correlation

    NASA Astrophysics Data System (ADS)

    Meinhardt, A.-K.; März, C.; Schuth, S.; Lettmann, K. A.; Schnetger, B.; Wolff, J.-O.; Brumsack, H.-J.

    2016-09-01

    Dark brown sediment layers are a potential stratigraphic tool in Quaternary Arctic Ocean sediments. They are rich in Mn, Fe, and trace metals scavenged from the water column and were most likely deposited during interglacial intervals. In this study, we combine sediment and pore water data from sediment cores taken in different parts of the Arctic Ocean to investigate the influence of early diagenetic processes on sediment geochemistry. In most studied cores, Mn, Co, and Mo are released into the pore waters from Mn oxide dissolution in deeper (>1.5 m) sediment layers. The relationship between sedimentary Mn, Co, and Mo contents in excess of the lithogenic background (elementxs) shows that Coxs/Moxs values are a diagnostic tool to distinguish between layers with diagenetic metal addition from the pore waters (Coxs/Moxs < 1), layers affected by Mn oxide dissolution and metal release (Coxs/Moxs > 10), and unaffected layers (Coxs/Moxs from 1 to 10). Steady-state calculations based on current pore water profiles reveal that in the studied cores, the diagenetic addition of these metals from the pore water pool alone is not sufficient to produce the sedimentary metal enrichments. However, it seems evident that dissolution of Mn oxides in the Mn reduction zone can permanently alter the primary geochemical signature of the dark brown layers. Therefore, pore water data and Coxs/Moxs values should be considered before core correlation when this correlation is solely based on Mn contents and dark sediment color. In contrast to the mostly non-lithogenic origin of Mn in the dark brown layers, sedimentary Fe consists of a large lithogenic (80%) and a small non-lithogenic fraction (20%). Our pore water data show that diagenetic Fe remobilization is not currently occurring in the sediment. The dominant Fe sources are coastal erosion and river input. Budget calculations show that Fe seems to be trapped in the modern Arctic Ocean and accumulates in shelf and basin sediments. The Fe