Sample records for total annual sediment

  1. Calculating net annual accumulation rates of sediment components exemplified by pollen

    Microsoft Academic Search

    Ulf Segerström; Ingemar Renberg

    1986-01-01

    The net annual accumulation rate of a sediment component can easily be estimated by determining the total content of the specific component (x) in a sediment sample, which represents a known number of years (yr) and certain area of the lake bottom (a), using the formula: annual accumulation = x\\/(yr·a). To illustrate and test this procedure we have calculated mean

  2. 24 CFR 886.308 - Maximum total annual contract commitment.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...total annual contract commitment. 886.308 Section...total annual contract commitment. (a) Number of units assisted. Based...for all the contract units in the project...maximum annual contract commitment per year...

  3. Concentrations and annual ?uxes of sediment-associated chemical constituents from conterminous US coastal rivers using bed sediment data

    USGS Publications Warehouse

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

    2012-01-01

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

  4. The measurement of total sediment load in alluvial streams

    USGS Publications Warehouse

    Benedict, P.C.; Matejka, D.Q.

    1953-01-01

    The measurement of the total sediment load transported by streams that flow in alluvial channels has been a perplexing problem to engineers and geologists for over a century. Until the last decade the development of equipment to measure bed load and suspended load was carried on almost independently, and without primary consideration of the fundamental laws governing the transportation of fluvial sediments. French investigators during the nineteenth century described methods of measurement and a mathematical approach for computing the rate of bed-load movement. The comprehensive laboratory investigations by Gilbert early in this century provided data that are still being used for studies of sediment transport. Detailed laboratory investigations of bed-load movement conducted during the last two decades by a number of investigators have resulted in the development of additional mathematical formulas for computing rates of bed-load movement. Likewise, studies of turbulent flow have provided the turbulence suspension theory for suspended sediment as it is known today.

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

    USGS Publications Warehouse

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

    2001-01-01

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

  6. Concentrations, loads, and yields of total phosphorus, total nitrogen, and suspended sediment and bacteria concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011-13

    USGS Publications Warehouse

    Buck, Stephanie D.

    2014-01-01

    The Poteau Valley Improvement Authority uses Wister Lake in southeastern Oklahoma as a public water supply. Total phosphorus, total nitrogen, and suspended sediments from agricultural runoff and discharges from wastewater treatment plants and other sources have degraded water quality in the lake. As lake-water quality has degraded, water-treatment cost, chemical usage, and sludge production have increased for the Poteau Valley Improvement Authority. The U.S. Geological Survey (USGS), in cooperation with the Poteau Valley Improvement Authority, investigated and summarized concentrations of total phosphorus, total nitrogen, suspended sediment, and bacteria (Escherichia coli and Enterococcus sp.) in surface water flowing to Wister Lake. Estimates of total phosphorus, total nitrogen, and suspended sediment loads, yields, and flow-weighted mean concentrations of total phosphorus and total nitrogen concentrations were made for the Wister Lake Basin for a 3-year period from October 2010 through September 2013. Data from water samples collected at fixed time increments during base-flow conditions and during runoff conditions at the Poteau River at Loving, Okla. (USGS station 07247015), the Poteau River near Heavener, Okla. (USGS station 07247350), and the Fourche Maline near Leflore, Okla. (USGS station 07247650), water-quality stations were used to evaluate water quality over the range of streamflows in the basin. These data also were collected to estimate annual constituent loads and yields by using regression models. At the Poteau River stations, total phosphorus, total nitrogen, and suspended sediment concentrations in surface-water samples were significantly larger in samples collected during runoff conditions than in samples collected during base-flow conditions. At the Fourche Maline station, in contrast, concentrations of these constituents in water samples collected during runoff conditions were not significantly larger than concentrations during base-flow conditions. Flow-weighted mean total phosphorus concentrations at all three stations from 2011 to 2013 were several times larger than the Oklahoma State Standard for Scenic Rivers (0.037 milligrams per liter [mg/L]), with the largest flow-weighted phosphorus concentrations typically being measured at the Poteau River at Loving, Okla., station. Flow-weighted mean total nitrogen concentrations did not vary substantially between the Poteau River stations and the Fourche Maline near Leflore, Okla., station. At all of the sampled water-quality stations, bacteria (Escherichia coli and Enterococcus sp.) concentrations were substantially larger in water samples collected during runoff conditions than in water samples collected during base-flow conditions from 2011 to 2013. Estimated annual loads of total phosphorus, total nitrogen, and suspended sediment in the Poteau River stations during runoff conditions ranged from 82 to 98 percent of the total annual loads of those constituents. Estimated annual loads of total phosphorus, total nitrogen, and suspended sediment in the Fourche Maline during runoff conditions ranged from 86 to nearly 100 percent of the total annual loads. Estimated seasonal total phosphorus loads generally were smallest during base-flow and runoff conditions in autumn. Estimated seasonal total phosphorus loads during base-flow conditions tended to be largest in winter and during runoff conditions tended to be largest in the spring. Estimated seasonal total nitrogen loads tended to be smallest in autumn during base-flow and runoff conditions and largest in winter during runoff conditions. Estimated seasonal suspended sediment loads tended to be smallest during base-flow conditions in the summer and smallest during runoff conditions in the autumn. The largest estimated seasonal suspended sediment loads during runoff conditions typically were in the spring. The estimated mean annual total phosphorus yield was largest at the Poteau River at Loving, Okla., water-quality station. The estimated mean annual total phosphorus yield was largest during base flow at the

  7. Annual maxima and totals of seasonally varying processes

    Microsoft Academic Search

    K. J. A. Revfeim

    1991-01-01

    The solar cycle induces strong periodicity in processes underlying monthly rainfall totals. Seasonally varying parameters of rainfall distributions can be estimated with reasonable reliability from relatively few years of monthly data. The distribution of annual totals or maxima in terms of these varying parameters can thus be used to predict long term annual characteristics from quite short records. Specification of

  8. Modelling of cohesive sediment transport in a tidal lagoon—an annual budget

    Microsoft Academic Search

    Ulrik Lumborg; Morten Pejrup

    2005-01-01

    The annual net sediment flux for an enclosed estuary is usually calculated as a residual value in sediment budget studies based mainly on sediment core dating. In this study, the numerical model MIKE 21 MT was used to directly model the annual net transport of cohesive sediment for the Lister Dyb tidal area in the northern part of the European

  9. Total Sediment Thickness of the World's Oceans and Marginal Seas

    NSDL National Science Digital Library

    This site consists of a digital total sediment thickness map and database for the world's oceans and marginal seas. The data are derived from previously published maps, ocean drilling results (Ocean Drilling Program and Deep Sea Drilling Project), and seismic reflection profiles (National Geophysical Data Center archives and Geological/Geophysical Atlas of the Pacific). Features include a JPEG image of the map, a downloadable data set available as either a NetCDF grd file or ASCII file, and bibliographical information.

  10. A study of the occurrence and distribution of bdellovibrios in estuarine sediment over an annual cycle

    Microsoft Academic Search

    H. N. Williams

    1988-01-01

    The recovery of bdellovibrios from estuarine sediments over an annual cycle was studied. Greater numbers of the predators were recovered in sediment than in the water column. Increases in the number of bdellovibrios recovered from sediment over various periods of time suggest that multiplication of the predators occurred. Sediment was observed to be an important ecosystem for the survival of

  11. Distribution of Total Mercury and Methyl Mercury in Water, Sediment, and Fish from South Florida Estuaries

    Microsoft Academic Search

    K. Kannan; R. F. Lee; H. L. Windom; P. T. Heitmuller; J. M. Macauley; J. K. Summers

    1998-01-01

    .   Concentrations of total mercury and methyl mercury were determined in sediment and fish collected from estuarine waters\\u000a of Florida to understand their distribution and partitioning. Total mercury concentrations in sediments ranged from 1 to 219\\u000a ng\\/g dry wt. Methyl mercury accounted for, on average, 0.77% of total mercury in sediment. Methyl mercury concentrations were\\u000a not correlated with total mercury

  12. ADJUSTMENT OF SEASONALLY ADJUSTED SERIES TO ANNUAL TOTALS

    Microsoft Academic Search

    Benoit Quenneville; Pierre Cholette; Guy Huot; Kim Chiu; Tommaso Di Fonzo

    This paper proposes methods to correct a seasonally adjusted series so that its annual totals match those of the raw series. The proposed methods are designed to preserve period-to-period movement like the Denton (1971) type of adjustments, but improve the adjustment at the ends. The methods can be applied to seasonally adjusted series obtained with any seasonal adjustment method such

  13. PCB congeners and hexachlorobenzene biota sediment accumulation factors for Macoma nasuta exposed to sediments with different total organic carbon contents

    Microsoft Academic Search

    Bruce L. Boese; H. II Lee; R. Randall; M. Winsor; S. Echols; J. Pelletier

    1995-01-01

    Deposit-feeding marine clams (Macoma nasuta) were exposed for 119 d to three sediment types that varied in total organic carbon (TOC) from 0.8 to 2.5%. Sediments were spiked with equal concentrations of 13 polychlorinated biphenyl congeners and hexachlorobenzene. Tissue residues were measured, and steady-state bioaccumulation factors (BAFs), the corresponding lipid, and TOC-normalized biota sediment accumulation factors (BSAFs) were determined. The

  14. An Accurate, Simple and Novel Analytical Method for the Determination of Total Organic Carbon in Sediment

    Microsoft Academic Search

    Nora F. Y. Tam; Michael W. Y. Yao

    1998-01-01

    An improvement to the Walkley-Black wet digestion method for accurate determination of total organic carbon (TOC) in mangrove and marine sediments was developed. Sediment samples were digested with acid dichromate in a domestic microwave for 7 minutes. The TOC results obtained from the proposed method were in excellent agreement with the conventional Walkley-Black method. The sediments were spiked with three

  15. River methane hot-spots: Continuous methane ebullition measurements over an annual cycle linked to river sediment production

    NASA Astrophysics Data System (ADS)

    Wilkinson, Jeremy; Maeck, Andreas; Ashboul, Zeyad; Lorke, Andreas

    2015-04-01

    Hot spot methane ebullition from impounded river reaches matches high rates observed around the globe. Ebullition dominates total methane flux in the Saar River (Germany) and is largely determined by sediment deposition rate. Using automated bubble traps developed in-house, and deployed over a year at four sites, we collected high resolution data showing that hydrodynamic disturbances from shipping, lock operations and hydrograph events trigger ebullition episodes. Reverse smoothing was used to integrate the observed ebullition back in time, and helped in visualizing the data, and provides a time-series closer to methane accumulation in the sediments, whereas ebullition shows the triggering and release of the accumulated gas. One major hydrological disturbance of shallow-water sediment released around 13% of the total annual ebullition at that site, and ebullition generally followed the seasonal sediment temperature variations. The same event damped ebullition from deeper water sites. Total annual ebullition values ranged from 200 to 500 gCH4 m-2 yr-1. Ebullition from shallow water sediments in winter ceased for extended periods, but continued un-broken from deeper sites. With on-going measurements we believe these findings will help to improve estimates and the modelling of methane emissions from impounded river systems.

  16. Total organic carbon in Lake Superior sediments: Comparisons with hemipelagic and pelagic marine environments1

    Microsoft Academic Search

    Thomas C. Johnson; James E. Evans; Steven J. Eisenreich

    Seventeen box cores from Lake Superior were analyzed for total organic carbon (TOC), porosity, and 210Pb activity. The data were trsed to determine relationships among bulk scdi- mentation rates, TOC sedimentation rates, and TOC degradation rates with depth in the core. Results are compared with predictive eqllations for TOC sedimentation rates and degradation rates in the oceans and show some

  17. Sedimentation rate, dilution, preservation and total organic carbon: some results of a modelling study

    Microsoft Academic Search

    R. V. Tyson

    2001-01-01

    A modelling exercise was undertaken to evaluate the positive (preservational) and negative (diluent) effects of sedimentation rate (SR) on the total organic carbon (TOC) content of marine sediments, and to use multiple regression analysis of modern data to predict TOC. Data presented show the predicted marine TOC using the carbon burial efficiency (BE) versus SR relationship of Betts and Holland

  18. TOTAL ORGANIC CARBON IN LAKE SUPERIOR SEDIMENTS: COMPARISONS WITH HEMIPELAGIC AND PELAGIC MARINE ENVIRONMENTS

    EPA Science Inventory

    Seventeen box cores from Lake Superior were analyzed for total organic carbon (TOC), porosity, and (210)Pb activity. The data were used to determine relationships among bulk sedimentation rates, TOC sedimentation rates, and TOC degradation rates with depth in the core. Results ar...

  19. Total nutrient and sediment loads, trends, yields, and nontidal water-quality indicators for selected nontidal stations, Chesapeake Bay Watershed, 1985–2011

    USGS Publications Warehouse

    Langland, Michael J.; Blomquist, Joel D.; Moyer, Douglas L.; Hyer, Kenneth E.; Chanat, Jeffrey G.

    2013-01-01

    The U.S. Geological Survey, in cooperation with Chesapeake Bay Program (CBP) partners, routinely reports long-term concentration trends and monthly and annual constituent loads for stream water-quality monitoring stations across the Chesapeake Bay watershed. This report documents flow-adjusted trends in sediment and total nitrogen and phosphorus concentrations for 31 stations in the years 1985–2011 and for 32 stations in the years 2002–2011. Sediment and total nitrogen and phosphorus yields for 65 stations are presented for the years 2006–2011. A combined nontidal water-quality indicator (based on both trends and yields) indicates there are more stations classified as “improving water-quality trend and a low yield” than “degrading water-quality trend and a high yield” for total nitrogen. The same type of 2-way classification for total phosphorus and sediment results in equal numbers of stations in each indicator class.

  20. Lateglacial calendar year chronology based on annually laminated sediments from Lake Meerfelder Maar, Germany

    Microsoft Academic Search

    Achim Brauer; Christoph Endres; Jörg F. W Negendank

    1999-01-01

    Annually laminated sediments from Lake Meerfelder Maar (MFM) in the Eifel, Germany, provide an independent calendar year timescale for the last glacial\\/interglacial transition. Changes in varve thickness and varve facies reflect significant environment variations during this period. The general micro facies pattern confirms that diatomaceous organic varves are favoured during warm climatic phases while cold periods generate higher allochthonous sediment

  1. PCB CONGENERS AND HEXACHLOROBENZENE BIOTA SEDIMENT ACCUMULATING FACTORS FOR MACOMA NASUTA EXPOSED TO SEDIMENTS WITH DIFFERENT TOTAL ORGANIC CARBON CONTENTS

    EPA Science Inventory

    Deposit-feeding marine clams (Macoma nasuta) were exposed for 119d to three sediment types that varied in total organic carbon (TOC) from 0.8 to 2.5%. ediments were spiked with equal concentrations of 13 polychlorinated biphenyl congeners and hexachlorobenzene. issue residues wer...

  2. Effects of lakes and reservoirs on annual river nitrogen, phosphorus, and sediment export in agricultural and forested landscapes

    USGS Publications Warehouse

    Powers, Steve M.; Robertson, Dale M.; Stanley, Emily H.

    2014-01-01

    Recently, effects of lakes and reservoirs on river nutrient export have been incorporated into landscape biogeochemical models. Because annual export varies with precipitation, there is a need to examine the biogeochemical role of lakes and reservoirs over time frames that incorporate interannual variability in precipitation. We examined long-term (~20?years) time series of river export (annual mass yield, Y, and flow-weighted mean annual concentration, C) for total nitrogen (TN), total phosphorus (TP), and total suspended sediment (TSS) from 54 catchments in Wisconsin, USA. Catchments were classified as small agricultural, large agricultural, and forested by use of a cluster analysis, and these varied in lentic coverage (percentage of catchment lake or reservoir water that was connected to river network). Mean annual export and interannual variability (CV) of export (for both Y and C) were higher in agricultural catchments relative to forested catchments for TP, TN, and TSS. In both agricultural and forested settings, mean and maximum annual TN yields were lower in the presence of lakes and reservoirs, suggesting lentic denitrification or N burial. There was also evidence of long-term lentic TP and TSS retention, especially when viewed in terms of maximum annual yield, suggesting sedimentation during high loading years. Lentic catchments had lower interannual variability in export. For TP and TSS, interannual variability in mass yield was often >50% higher than interannual variability in water yield, whereas TN variability more closely followed water (discharge) variability. Our results indicate that long-term mass export through rivers depends on interacting terrestrial, aquatic, and meteorological factors in which the presence of lakes and reservoirs can reduce the magnitude of export, stabilize interannual variability in export, as well as introduce export time lags.

  3. 16 CFR 801.11 - Annual net sales and total assets.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...Practices FEDERAL TRADE COMMISSION RULES, REGULATIONS, STATEMENTS AND INTERPRETATIONS UNDER THE HART-SCOTT-RODINO ANTITRUST IMPROVEMENTS ACT OF 1976 COVERAGE RULES § 801.11 Annual net sales and total assets. (a) The annual net...

  4. Investigation of Total and Methyl Mercury in Fish and Sediment of Lake Michigan

    EPA Science Inventory

    Sediment cores and fish collected between 1994 and 1996 as part of the Lake Michigan Mass Balance Project were analyzed for total and methyl mercury. Results of the fish analyses are being used to describe total and methyl mercury concentrations in forage fish and lake trout, re...

  5. Sediment concentration prediction and statistical evaluation for annual load estimation

    NASA Astrophysics Data System (ADS)

    Wang, You-Gan; Tian, Ting

    2013-03-01

    SummaryWe consider the development of statistical models for prediction of constituent concentration of riverine pollutants, which is a key step in load estimation from frequent flow rate data and less frequently collected concentration data. We consider how to capture the impacts of past flow patterns via the average discounted flow (ADF) which discounts the past flux based on the time lapsed - more recent fluxes are given more weight. However, the effectiveness of ADF depends critically on the choice of the discount factor which reflects the unknown environmental cumulating process of the concentration compounds. We propose to choose the discount factor by maximizing the adjusted R2 values or the Nash-Sutcliffe model efficiency coefficient. The R2 values are also adjusted to take account of the number of parameters in the model fit. The resulting optimal discount factor can be interpreted as a measure of constituent exhaustion rate during flood events. To evaluate the performance of the proposed regression estimators, we examine two different sampling scenarios by resampling fortnightly and opportunistically from two real daily datasets, which come from two United States Geological Survey (USGS) gaging stations located in Des Plaines River and Illinois River basin. The generalized rating-curve approach produces biased estimates of the total sediment loads by -30% to 83%, whereas the new approaches produce relatively much lower biases, ranging from -24% to 35%. This substantial improvement in the estimates of the total load is due to the fact that predictability of concentration is greatly improved by the additional predictors.

  6. Annually-laminated lake sediments and the study of Quaternary environmental changes — a review

    NASA Astrophysics Data System (ADS)

    O'Sullivan, P. E.

    Annually-laminated lake sediments (non-glacial varves) have in recent years been discovered in increasing abundance, especially since the development of in situ freezer samplers. So far, the majority of examples have been found in three main areas (Eastern North America, Northern and Central Europe, and East and Central Africa). A much more widespread distribution seems highly probable however. The formation of annual laminations in freshwater lakes is governed by a number of factors, the most important of which appears to be morphometry. Seasonality of sediment supply, which may be controlled by physical, biological or even cultural processes in the lake, or in its catchment, is also clearly significant. Four main types of laminations (here termed ferrogenic, calcareous, biogenic and clastic) have so far been recorded, although it is quite clear that others exist. Special field and laboratory techniques are needed in order that the particular properties of varved sediments may be fully exploited. Annually-laminated sediments have so far been applied to the investigation of a number of aspects of the Quaternary. These include the study of (a) geochronology (b) climatic change, (c) vegetation history, especially the role of fire in forest ecosystems, (d) the calculation of rates of sediment influx to lakes, and of rates of erosion from their catchments, and (e) the monitoring of processes in the modern environment such as heavy metal pollution, eutrophication, and 'acid rain'. Annually-laminated lake sediments combine an internal, independent chronology with the preservation of discrete, visible increments of seasonal and annual sedimentation. Given this unique property, and the likelihood that many more examples will be discovered, the prospects for further applications of studies of these sediments to the investigation of the Quaternary seem very good indeed.

  7. Total and methyl mercury in wetland soils and sediments of Louisiana's Pontchartrain Basin (USA).

    PubMed

    Yu, Kewei; Delaune, Ronald D; Devai, Istvan; Tao, Rui; Jugsujinda, Aroon

    2008-12-01

    Accumulation of methylmercury (MeHg) in aquatic biota is a primary toxicological concern associated with Hg contamination in the environment. This study reports total mercury (THg) and MeHg measurements in 11 swamp and 24 marsh soils/sediments in wetlands surrounding Lake Pontchartrain and Lake Maurepas located in Louisiana's Pontchartrain Basin. The salinity level ranged from fresh, brackish to salt water. Average THg content in the swamp soils/sediments (112.3 microg kg(-1), n = 10) was significantly higher (P = 0.04) than in the marsh soils/sediments (56.5 microg kg(-1), n = 24). The THg content in the marsh soils/sediments tended to decrease with salinity increase, probably due to geographical locations of the sampling sites with less Hg input in more saline regions. Average MeHg content in the soils/sediments was 1.3 microg kg(-1) (n = 34), higher than reported values in the bottom sediments of Lake Maurepas (0.8 microg kg(-1), n = 27) and Lake Pontchartrain (0.6 microg kg(-1), n = 147). Average MeHg/THg ratio in the marsh soils/sediments (0.022) was considerably higher than in the swamp soils/sediments (0.012). Analysis of MeHg/THg ratio along the salinity gradient at the marsh soils/sediments show that the highest MeHg/THg ratio (up to 0.040, n = 5) was found at the fresh/brackish water sites, and the lowest (0.002, n = 1) at the salt water site. Results suggest that there was a greater potential for MeHg formation in wetland soils/sediments than in bottom sediments of adjacent lakes. Results suggest that wetland surrounding the lakes may be a potential source of MeHg to the aquatic food chain and significance is governed by area of the adjacent wetland. PMID:18988103

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

    USGS Publications Warehouse

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

    2014-01-01

    Sediment-laden rivers and streams pose substantial environmental and economic challenges. Excessive sediment transport in rivers causes problems for flood control, soil conservation, irrigation, aquatic health, and navigation, and transports harmful contaminants like organic chemicals and eutrophication-causing nutrients. In Minnesota, more than 5,800 miles of streams are identified as impaired by the Minnesota Pollution Control Agency (MPCA) due to elevated levels of suspended sediment. The U.S. Geological Survey, in cooperation with the MPCA, established a sediment monitoring network in 2007 and began systematic sampling of suspended-sediment concentrations (SSC), total suspended solids (TSS), and turbidity in rivers across Minnesota to improve the understanding of fluvial sediment transport relations. Suspended-sediment samples collected from 14 sites from 2007 through 2011 indicated that the Zumbro River at Kellogg in the driftless region of southeast Minnesota had the highest mean SSC of 226 milligrams per liter (mg/L) followed by the Minnesota River at Mankato with a mean SSC of 193 mg/L. During the 2011 spring runoff, the single highest SSC of 1,250 mg/L was measured at the Zumbro River. The lowest mean SSC of 21 mg/L was measured at Rice Creek in the northern Minneapolis- St. Paul metropolitan area. Total suspended solids (TSS) have been used as a measure of fluvial sediment by the MPCA since the early 1970s; however, TSS concentrations have been determined to underrepresent the amount of suspended sediment. Because of this, the MPCA was interested in quantifying the differences between SSC and TSS in different parts of the State. Comparisons between concurrently sampled SSC and TSS indicated significant differences at every site, with SSC on average two times larger than TSS concentrations. The largest percent difference between SSC and TSS was measured at the South Branch Buffalo River at Sabin, and the smallest difference was observed at the Des Moines River at Jackson. Regression analysis indicated that 7 out of 14 sites had poor or no relation between SSC and streamflow. Only two sites, the Knife River and the Wild Rice River at Twin Valley, had strong correlations between SSC and streamflow, with coefficient of determination (R2) values of 0.82 and 0.80, respectively. In contrast, turbidity had moderate to strong relations with SSC at 10 of 14 sites and was superior to streamflow for estimating SSC at all sites. These results indicate that turbidity may be beneficial as a surrogate for SSC in many of Minnesota’s rivers. Suspended-sediment loads and annual basin yields indicated that the Minnesota River had the largest average annual sediment load of 1.8 million tons per year and the largest mean annual sediment basin yield of 120 tons of sediment per year per square mile. Annual TSS loads were considerably lower than suspended-sediment loads. Overall, the largest suspended-sediment and TSS loads were transported during spring snowmelt runoff, although loads during the fall and summer seasons occasionally exceeded spring runoff at some sites. This study provided data from which to characterize suspended sediment across Minnesota’s diverse geographical settings. The data analysis improves understanding of sediment transport relations, provides information for improving sediment budgets, and documents baseline data to aid in understanding the effects of future land use/land cover on water quality. Additionally, the data provides insight from which to evaluate the effectiveness and efficiency of best management practices at the watershed scale.

  9. The partitioning of the total sediment load of a river into suspended load and bedload

    Microsoft Academic Search

    J. M. Turowski; D. Rickenmann; S. J. Dadson

    2009-01-01

    The partitioning of the total sediment load of a river into suspended load and bedload is an important problem in fluvial geomorphology and sedimentation engineering: Bedload transport rates are notoriously hard to measure and at many sites only suspended load data is available. Often the bedload fraction is estimated with rule-of-thumb methods, which are inadequately field-tested. Here we discuss the

  10. Annual suspended sediment and trace element fluxes in the Mississippi, Columbia, Colorado, and Rio Grande drainage basins

    NASA Astrophysics Data System (ADS)

    Horowitz, Arthur J.; Elrick, Kent A.; Smith, James J.

    2001-05-01

    Suspended sediment, sediment-associated, total trace element, phosphorus (P), and total organic carbon (TOC) fluxes were determined for the Mississippi, Columbia, Rio Grande, and Colorado Basins for the study period (the 1996, 1997, and 1998 water years) as part of the US Geological Survey's redesigned National Stream Quality Accounting Network (NASQAN) programme. The majority (70%) of Cu, Zn, Cr, Ni, Ba, P, As, Fe, Mn, and Al are transported in association with suspended sediment; Sr transport seems dominated by the dissolved phase, whereas the transport of Li and TOC seems to be divided equally between both phases. Average dissolved trace element levels are markedly lower than reported during the original NASQAN programme; this seems due to the use of clean sampling, processing, and analytical techniques rather than to improvements in water quality. Partitioning between sediment and water for Ag, Pb, Cd, Cr, Co, V, Be, As, Sb, Hg, and Ti could not be estimated due to a lack of detectable dissolved concentrations in most samples.Elevated suspended sediment-associated Zn levels were detected in the Ohio River Basin and elevated Hg levels were detected in the Tennessee River, the former may affect the mainstem Mississippi River, whereas the latter probably do not. Sediment-associated concentrations of Ag, Cu, Pb, Zn, Cd, Cr, Co, Ba, Mo, Sb, Hg, and Fe are markedly elevated in the upper Columbia Basin, and appear to be detectable (Zn, Cd) as far downstream as the middle of the basin. These elevated concentrations seem to result from mining and/or mining-related activities. Consistently detectable concentrations of dissolved Se were found only in the Colorado River Basin.Calculated average annual suspended sediment fluxes at the mouths of the Mississippi and Rio Grande Basins were below, whereas those for the Columbia and Colorado Basins were above previously published annual values. Downstream suspended sediment-associated and total trace element fluxes increase in the Mississippi and Columbia Basins, whereas fluxes markedly decrease in the Colorado Basin. No consistent pattern in trace element fluxes was detected in the Rio Grande Basin. Published in 2001 by John Wiley & Sons, Ltd.

  11. Annual suspended sediment and trace element fluxes in the Mississippi, Columbia, Colorado, and Rio Grande drainage basins

    USGS Publications Warehouse

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

    2001-01-01

    Suspended sediment, sediment-associated, total trace element, phosphorus (P), and total organic carbon (TOC) fluxes were determined for the Mississippi, Columbia, Rio Grande, and Colorado Basins for the study period (the 1996, 1997, and 1998 water years) as part of the US Geological Survey's redesigned National Stream Quality Accounting Network (NASQAN) programme. The majority (??? 70%) of Cu, Zn, Cr, Ni, Ba, P, As, Fe, Mn, and Al are transported in association with suspended sediment; Sr transport seems dominated by the dissolved phase, whereas the transport of Li and TOC seems to be divided equally between both phases. Average dissolved trace element levels are markedly lower than reported during the original NASQAN programme; this seems due to the use of 'clean' sampling, processing, and analytical techniques rather than to improvements in water quality. Partitioning between sediment and water for Ag, Pb, Cd, Cr, Co, V, Be, As, Sb, Hg, and Ti could not be estimated due to a lack of detectable dissolved concentrations in most samples. Elevated suspended sediment-associated Zn levels were detected in the Ohio River Basin and elevated Hg levels were detected in the Tennessee River, the former may affect the mainstem Mississippi River, whereas the latter probably do not. Sediment-associated concentrations of Ag, Cu, Pb, Zn, Cd, Cr, Co, Ba, Mo, Sb, Hg, and Fe are markedly elevated in the upper Columbia Basin, and appear to be detectable (Zn, Cd) as far downstream as the middle of the basin. These elevated concentrations seem to result from mining and/or mining-related activities. Consistently detectable concentrations of dissolved Se were found only in the Colorado River Basin. Calculated average annual suspended sediment fluxes at the mouths of the Mississippi and Rio Grande Basins were below, whereas those for the Columbia and Colorado Basins were above previously published annual values. Downstream suspended sediment-associated and total trace element fluxes increase in the Mississippi and Columbia Basins, whereas fluxes markedly decrease in the Colorado Basin. No consistent pattern in trace element fluxes was detected in the Rio Grande Basin.

  12. Predictability of Annual Sediment Loads Based on Flood Events

    Microsoft Academic Search

    Momcilo Markus

    2006-01-01

    Water resources managers always are searching for cost-effective monitoring programs that provide maximum information for minimum cost. Monitoring of sediment discharges from streams and rivers is one of the expensive efforts that is always reduced or cut when financial resources are limited. This has resulted in a very limited number of long-term sediment monitoring sites in the United States. Instead

  13. 12 CFR Appendix K to Part 226 - Total Annual Loan Cost Rate Computations for Reverse Mortgage Transactions

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...Total Annual Loan Cost Rate Computations for Reverse Mortgage Transactions K Appendix K...Annual Loan Cost Rate Computations for Reverse Mortgage Transactions (a) Introduction...of total annual loan cost rates for each reverse mortgage transaction. This...

  14. 12 CFR Appendix K to Part 226 - Total Annual Loan Cost Rate Computations for Reverse Mortgage Transactions

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...Total Annual Loan Cost Rate Computations for Reverse Mortgage Transactions K Appendix K...Annual Loan Cost Rate Computations for Reverse Mortgage Transactions (a) Introduction...of total annual loan cost rates for each reverse mortgage transaction. This...

  15. Distribution of total and methyl mercury in sediments along Steamboat Creek (Nevada, USA)

    USGS Publications Warehouse

    Stamenkovic, J.; Gustin, M.S.; Marvin-DiPasquale, M. C.; Thomas, B.A.; Agee, J.L.

    2004-01-01

    In the late 1800s, mills in the Washoe Lake area, Nevada, used elemental mercury to remove gold and silver from the ores of the Comstock deposit. Since that time, mercury contaminated waste has been distributed from Washoe Lake, down Steamboat Creek, and to the Truckee River. The creek has high mercury concentrations in both water and sediments, and continues to be a constant source of mercury to the Truckee River. The objective of this study was to determine concentrations of total and methyl mercury (MeHg) in surface sediments and characterize their spatial distribution in the Steamboat Creek watershed. Total mercury concentrations measured in channel and bank sediments did not decrease downstream, indicating that mercury contamination has been distributed along the creek's length. Total mercury concentrations in sediments (0.01-21.43 ??g/g) were one to two orders of magnitude higher than those in pristine systems. At 14 out of 17 sites, MeHg concentrations in streambank sediments were higher than the concentrations in the channel, suggesting that low banks with wet sediments might be important sites of mercury methylation in this system. Both pond/wetland and channel sites exhibited high potential for mercury methylation (6.4-30.0 ng g-1 day-1). Potential methylation rates were positively correlated with sulfate reduction rates, and decreased as a function of reduced sulfur and MeHg concentration in the sediments. Potential demethylation rate appeared not to be influenced by MeHg concentration, sulfur chemistry, DOC, sediment grain size or other parameters, and showed little variation across the sites (3.7-7.4 ng g-1 day-1). ?? 2003 Elsevier B.V. All rights reserved.

  16. Distribution of surficial sediment in Long Island Sound and adjacent waters: Texture and total organic carbon

    USGS Publications Warehouse

    Poppe, L.J.; Knebel, H. J.; Mlodzinska, Z.J.; Hastings, M.E.; Seekins, B.A.

    2000-01-01

    The surficial sediment distribution within Long Island Sound has been mapped and described using bottom samples, photography, and sidescan sonar, combined with information from the geologic literature. The distributions of sediment type and total organic carbon (TOC) reveal several broad trends that are largely related to the sea-floor geology, the bathymetry, and the effects of modern tidal- and wind-driven currents. Sediment types are most heterogeneous in bathymetrically complex and shallow nearshore areas; the heterogeneity diminishes and the texture fines with decreasing bottom-current energy. Lag deposits of gravel and gravelly sand dominate the surficial sediment texture in areas where bottom currents are the strongest (such as where tidal flow is constricted) and where glacial till crops out at the sea floor. Sand is the dominant sediment type in areas characterized by active sediment transport and in shallow areas affected by fine-grained winnowing. Silty sand and sand-silt-clay mark transitions within the basin from higher- to lower-energy environments, suggesting a diminished hydraulic ability to sort and transport sediment. Clayey silt and silty clay are the dominant sediment types accumulating in the central and western basins and in other areas characterized by long-term depositional environments. The amount of TOC in the sediments of Long Island Sound varies inversely with sediment grain size. Concentrations average more than 1.9% (dry weight) in clayey silt, but are less than 0.4% in sand. Generally, values for TOC increase both toward the west in the Sound and from the shallow margins to the deeper parts of the basin floor. Our data also suggest that TOC concentrations can vary seasonally.

  17. Distribution of total mercury and methylmercury in lake sediments in Arctic Ny-?lesund.

    PubMed

    Jiang, Shan; Liu, Xiaodong; Chen, Qianqian

    2011-05-01

    The toxicities and bioavailabilities of total mercury (THg) and methylmercury (MeHg) in aquatic systems have made them the subjects of recent research. In this study, we collected a lake sediment core from Ny-?lesund in Svalbard and analyzed the distributions of THg and MeHg in the sediments. The increased trend of THg was caused by anthropogenic contamination since the 14th century through long-range transportation, especially after the industrial era. However, the peak values of Hg in surface sediment samples could be explained by the increased algal scavenging process in recent decades. All the biogeochemical proxies (e.g., pigments and diatom biomass) revealed recent sharp increases in aquatic primary production due to the current climate warming. Rock-Eval analyses indicated that algal-derived organic matter took up a large portion, and quantitative calculation showed that 89.6-95.8% of the Hg in post-1950 could be explained by scavenging. The distribution of MeHg has a close relationship with total Hg and organic matter. The oxidation-reduction condition is one of the possible factors affecting the methylation rates in H2 lake sediments. Higher algal productivity and organic matter actually led to the increased trend of methylation in the uppermost sediment. This study supports some new key hypotheses on climate-driven factors affecting Hg and MeHg cycling in High Arctic lake sediments. PMID:21306754

  18. Ecosystem engineering by annual intertidal seagrass beds: Sediment accretion and modification

    NASA Astrophysics Data System (ADS)

    Bos, Arthur R.; Bouma, Tjeerd J.; de Kort, Geertje L. J.; van Katwijk, Marieke M.

    2007-08-01

    Seagrasses are generally known as ecosystem engineers, as they reduce flow velocities in their canopies. In perennial subtidal meadows, this usually leads to increased net sedimentation rates and reduction of the grain size. The present study aims to describe the contribution of annual seagrass populations to these processes and elucidate the temporal dynamics. Sediment accretion and grain size modification were experimentally tested by transplanting seedlings of an annual intertidal eelgrass population to an unvegetated tidal flat. Within the planting units (79 shoots m -2) 4.7 mm of sediment accreted, whereas in the most dense parts of these units (199 shoots m -2) accretion amounted to 7.1 mm. The silt fraction (<63 ?m) increased and the sand fraction (63-500 ?m) decreased in the eelgrass beds, which provides evidence that higher silt content in seagrass beds is the result and not the cause of seagrass presence. Annual intertidal eelgrass beds significantly contribute to the immobilisation of sediment during the growing season with its magnitude depending on canopy density. During winter, the accumulated sediments were released again and could even induce additional erosion. Possible consequences of these sediment dynamics for the larger scale functioning of estuarine ecosystems are discussed.

  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. Effective Discharge and Annual Sediment Yield on Brazos River

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  1. Impact of total organic carbon (in sediments) and dissolved organic carbon (in overlying water column) on Hg sequestration by coastal sediments from the central east coast of India.

    PubMed

    Chakraborty, Parthasarathi; Sharma, Brijmohan; Babu, P V Raghunath; Yao, Koffi Marcellin; Jaychandran, Saranya

    2014-02-15

    Total organic carbon (TOC) (in sediment) and dissolved organic matter (DOM) (in water column) play important roles in controlling the mercury sequestration process by the sediments from the central east coast of India. This toxic metal prefers to associate with finer size particles (silt and clay) of sediments. Increasing concentrations of DOM in overlying water column may increase complexation/reduction processes of Hg(2+) within the water column and decrease the process of Hg sequestration by sediments. However, high concentrations of DOM in water column may increase Hg sequestration process by sediments. PMID:24355570

  2. The effects of sample scheduling and sample numbers on estimates of the annual fluxes of suspended sediment in fluvial systems

    USGS Publications Warehouse

    Horowitz, Arthur J.; Clarke, Robin T.; Merten, Gustavo Henrique

    2015-01-01

    Since the 1970s, there has been both continuing and growing interest in developing accurate estimates of the annual fluvial transport (fluxes and loads) of suspended sediment and sediment-associated chemical constituents. This study provides an evaluation of the effects of manual sample numbers (from 4 to 12?year?1) and sample scheduling (random-based, calendar-based and hydrology-based) on the precision, bias and accuracy of annual suspended sediment flux estimates. The evaluation is based on data from selected US Geological Survey daily suspended sediment stations in the USA and covers basins ranging in area from just over 900?km2 to nearly 2?million?km2 and annual suspended sediment fluxes ranging from about 4?Kt?year?1 to about 200?Mt?year?1. The results appear to indicate that there is a scale effect for random-based and calendar-based sampling schemes, with larger sample numbers required as basin size decreases. All the sampling schemes evaluated display some level of positive (overestimates) or negative (underestimates) bias. The study further indicates that hydrology-based sampling schemes are likely to generate the most accurate annual suspended sediment flux estimates with the fewest number of samples, regardless of basin size. This type of scheme seems most appropriate when the determination of suspended sediment concentrations, sediment-associated chemical concentrations, annual suspended sediment and annual suspended sediment-associated chemical fluxes only represent a few of the parameters of interest in multidisciplinary, multiparameter monitoring programmes. The results are just as applicable to the calibration of autosamplers/suspended sediment surrogates currently used to measure/estimate suspended sediment concentrations and ultimately, annual suspended sediment fluxes, because manual samples are required to adjust the sample data/measurements generated by these techniques so that they provide depth-integrated and cross-sectionally representative data. 

  3. Variations in trace metal and total organic carbon concentrations in marine sediments from Hong Kong

    Microsoft Academic Search

    P. A. Tanner; J. W. C. James; K. Chan; L. S. Leong

    1993-01-01

    Four marine cores to depth of 2.8 m, from the Urmston Road?Brothers Channel, Hong Kong, have been analyzed for the trace metals Cu, Zn, Cr, Ni, Mn and Pb, as well as total organic carbon and organochlorines. Most of these elements indicate enhanced concentrations due to anthropogenic inputs in the upper part of the sediment column, with an overall decrease

  4. Spatial and Habitat-Based Variations in Total and Methyl Mercury Concentrations in Surficial Sediments in the San Francisco Bay-Delta

    SciTech Connect

    Heim, Wesley A.; Coale, Kenneth H.; Stephenson, Mark; Choe, Key-Young; Gill, Gary A.; Foe, Chris

    2007-04-07

    Recent studies indicate significant amounts of mercury (Hg) are annually transported into the San Francisco Bay-Delta (Bay-Delta) as a result of historic gold and Hg mining activities. We examined temporal and spatial variation in concentrations of total Hg (HgT) and monomethylmercury (MMHg) in surficial sediments of various ecosystem types in the Bay-Delta. We sampled surficial sediments across the Bay-Delta system and found HgT sediment concentrations in the central Delta were generally100-200 ng g-1 and increased westward through Suisun Bay to 250-350 ng g-1. MMHg concentrations in the central Delta were between 1 and 3 ng g-1, while those in sediments in the perimeter waterways and adjacent bays were less than 1 ng g-1. Six sites were monitored monthly for over a year to identify seasonal changes in Hg sediment concentrations. HgT sediment concentrations ranged from 48 to 382 ng g-1 and varied as a function of location not season. However, MMHg concentrations varied seasonally, increasing from 1 ng g-1 during winter months to 6 ng g-1 during spring and summer. Transects conducted at three marshes in the central Delta revealed MMHg sediment concentrations of 4-8 ng g-1at the interior and 2 ng g-1 at the exterior of the marshes. Habitat type was a major factor controlling MMHg concentration and the MMHg to HgT ratio in sediments of the Bay-Delta. MMHg was significantly correlated to HgT (r 2 = 0.49) in marsh sediments.

  5. Evidence of annual layering in Holocene sediments of Soppensee, Switzerland

    Microsoft Academic Search

    André F. Lotter

    1989-01-01

    A succession of fine dark and light laminations, covering a time span of ca 6,000 years (Allerød to Atlantic), was observed in the sediment of Soppensee, Central Switzerland. These laminations, consisting of dark, organic and diatom-rich winter\\/spring layers and light calcite summer layers, are shown to be varves by means of several independent pollen and diatom analyses, as well as

  6. Sediment-Porewater Partitioning, Total Sulfur and Methylmercury Production in Estuaries

    PubMed Central

    Schartup, Amina T.; Balcom, Prentiss H.; Mason, Robert P.

    2014-01-01

    Mercury (Hg) speciation and the activity of Hg(II)-methylating bacteria are responsible for the rate of methylmercury (MeHg) production and thus bioaccumulation in marine foodwebs. Factors affecting porewater partitioning (Kd) and methylation of Hg(II) were examined at 11 sites in sediment of 4 biogeochemically diverse estuaries in the Northeast U. S. In Long Island Sound, 88% of total mercury (HgT) log Kd variability was described by porewater dissolved organic carbon concentration and sediment total sulfur (S) content. Whereas across all estuaries, regression analyses showed that S alone drives about 70% of Kd variability and 50% of changes in methylation rates; and the inclusion of DOC and sulfides did not improve the prediction. Thus, we demonstrated that S is a better predictor of HgT log Kd than the sediment organic matter across multiple estuaries, and while organic matter and S are interchangeable in small-scale studies, on a larger scale, sediment S content is the simplest and most effective variable to measure. PMID:24344684

  7. Sediment-porewater partitioning, total sulfur, and methylmercury production in estuaries.

    PubMed

    Schartup, Amina T; Balcom, Prentiss H; Mason, Robert P

    2014-01-21

    Mercury (Hg) speciation and the activity of Hg(II)-methylating bacteria are responsible for the rate of methylmercury production and thus bioaccumulation in marine foodwebs. Factors affecting porewater partitioning (Kd) and methylation of Hg(II) were examined at 11 sites in sediment of 4 biogeochemically diverse estuaries in the Northeast U.S. In Long Island Sound, 88% of total mercury (HgT) log Kd variability was described by porewater dissolved organic carbon concentration and sediment total sulfur (S) content. Whereas across all estuaries, regression analyses showed that S alone drives about 70% of Kd variability and 50% of changes in methylation rates; and the inclusion of DOC and sulfides did not improve the prediction. Thus, we demonstrated that S is a better predictor of HgT log Kd than the sediment organic matter across multiple estuaries, and while organic matter and S are interchangeable in small-scale studies, on a larger scale, sediment S content is the simplest and most effective variable to measure. PMID:24344684

  8. Total mercury and methylmercury distributions in surface sediments from Kongsfjorden, Svalbard, Norwegian Arctic.

    PubMed

    Liu, Yang; Chai, Xiaoli; Hao, Yongxia; Gao, Xiaofeng; Lu, Zhibo; Zhao, Youcai; Zhang, Jie; Cai, Minghong

    2015-06-01

    The total mercury (THg) and methylmercury (MeHg) distributions in the surface sediments of Kongsfjorden, Svalbard, in the Norwegian Arctic were investigated in this study. The results showed that THg concentrations ranged from 9.11 to 86.73 ng g(-1), whereas MeHg concentrations had an average of only 0.11 ng g(-1). Factors that control the distribution and methylated transformation of mercury were examined, and the results suggested that the movements of ocean currents and glaciers affect the THg distribution. The total organic carbon (TOC) and N contents in the sediments were positively correlated with THg concentration, which indicated that the THg distribution at these stations was primarily controlled by organic matter in the sediments. A complex relationship was observed between the THg and S contents, possibly due to anthropogenic activities involved in the perennial scientific expedition. MeHg and THg exhibited similar correlations with the sediment chemical characteristics for all stations suggesting that MeHg may be produced locally through the microbial methylation of mercury. PMID:25563828

  9. Isotope analyses of molecular and total organic carbon from miocene sediments

    Microsoft Academic Search

    Mark Pagani; KATHERINE H. FREEMAN; MICHAEL A. ARTHUR

    2000-01-01

    Carbon-isotope compositions of n-alkanes, pristane and phytane, and total organic carbon were measured and compared against isotopic trends of coeval alkadienones from Miocene sediments containing very low organic-carbon contents. Compound-specific isotope analysis of n-alkanes and isoprenoid lipids, in conjunction with abundance distributions of n-alkanes reveal the influence of terrestrially derived organic carbon at all sites analyzed. In general, n-alkanes are

  10. Total metal levels in crayfish Astacus leptodactylus (Eschscholtz, 1823), and surface sediments in Lake Terkos, Turkey.

    PubMed

    Kurun, Aysegül; Balkis, Nuray; Erkan, Melike; Balkis, Hüsamettin; Aksu, Abdullah; Er?an, Mahmut Selim

    2010-10-01

    The aim of this study was to determine the total metal accumulation (aluminium, copper, manganese, lead, cadmium and iron) in different organs and eggs of Astacus leptodactylus (Eschscholtz, 1823) and sediments total metal contents (aluminium, copper, manganese, lead, cadmium, iron, zinc, chromium, nickel) in Lake Terkos. Water and sediment samples were collected from two stations at two different depths (1 and 2 m) of Lake Terkos in May 2008. Crayfish samples were collected by trammel net at the same region. Primary hydrographic conditions, such as temperature (13.6-19.4 degrees C), salinity (0.27-0.34 per thousand), dissolved oxygen (7.04-12.30 mg l(-1)) and pH (7.42-8.51), were recorded for each sampling point. Moreover, the total organic carbon (1.65-5.44%) and the total calcium carbonate contents (19.44-41.16%) of sediment samples were determined. According to the Turkish Food Codex (J Zool 26:283-288, 2002), the maximum allowable Pb and Cd levels in crayfish are 0.5 mg/kg wet weight. Accordingly, the Pb and Cd levels determined in A. leptodactylus samples are below this limit. However, when compared with the acceptable metal limits defined by WHO, Australian National Health and Medical Research Council and Ministry of Agriculture in United Kingdom (UK), it is clear that the Cu level is at the limit and the Cd results exceed the limit. When the metal contents in sediment samples from Lake Terkos are examined, it is seen that the Al, Fe, Mn, Ni and Cu contents are lower while Zn, Cr, Cd and Pb contents are higher than the crustal average values. The high values draw attention to the land-based domestic and industrial inputs. Lake Terkos sediments have high enrichment factors (EF) of Zn, Cr, Cd and Pb metals which corroborate this result. The low EFs of Fe, Ni and Cu are due to the natural (terrigeneous) inputs. Additionally, there is no Al, Fe, Ni and Cu metal enrichment in these lake sediments because of the low contamination factor (CF) values. However, it is moderately contaminated by Zn, Cr and Pb, and heavily contaminated by Cd. PMID:19847663

  11. 16 CFR 801.11 - Annual net sales and total assets.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...Section 801.11 Commercial Practices FEDERAL TRADE COMMISSION RULES, REGULATIONS, STATEMENTS AND INTERPRETATIONS UNDER THE HART-SCOTT-RODINO ANTITRUST IMPROVEMENTS ACT OF 1976 COVERAGE RULES § 801.11 Annual net sales and total...

  12. Pluri-annual sediment budget in a navigated river system: the Seine River (France).

    PubMed

    Vilmin, Lauriane; Flipo, Nicolas; de Fouquet, Chantal; Poulin, Michel

    2015-01-01

    This study aims at quantifying pluri-annual Total Suspended Matter (TSM) budgets, and notably the share of river navigation in total re-suspension at a long-term scale, in the Seine River along a 225 km stretch including the Paris area. Erosion is calculated based on the transport capacity concept with an additional term for the energy dissipated by river navigation. Erosion processes are fitted for the 2007-2011 period based on i) a hydrological typology of sedimentary processes and ii) a simultaneous calibration and retrospective validation procedure. The correlation between observed and simulated TSM concentrations is higher than 0.91 at all monitoring stations. A variographic analysis points out the possible sources of discrepancies between the variabilities of observed and simulated TSM concentrations at three time scales: sub-weekly, monthly and seasonally. Most of the error on the variability of simulated concentrations concerns sub-weekly variations and may be caused by boundary condition estimates rather than modeling of in-river processes. Once fitted, the model permits to quantify that only a small fraction of the TSM flux sediments onto the river bed (<0.3‰). The river navigation contributes significantly to TSM re-suspension in average (about 20%) and during low flow periods (over 50%). Given the significant impact that sedimentary processes can have on the water quality of rivers, these results highlight the importance of taking into account river navigation as a source of re-suspension, especially during low flow periods when biogeochemical processes are the most intense. PMID:25241208

  13. Importance of Dissolved Neutral Hg-Sulfides, Energy Rich Organic Matter and total Hg Concentrations for Methyl Mercury Production in Sediments

    NASA Astrophysics Data System (ADS)

    Drott, A.; Skyllberg, U.

    2007-12-01

    Methyl mercury (MeHg) is the mercury form that biomagnifies to the greatest extent in aquatic food webs. Therefore information about factors determining MeHg concentrations is critical for accurate risk assessment of contaminated environments. The concentration of MeHg in wetlands and sediments is the net result of: 1) methylation rates, 2) demethylation rates, and 3) input/output processes. In this study, the main controls on Hg methylation rates and total concentrations of MeHg, were investigated at eight sites in Sweden with sediments that had been subjected to local Hg contamination either as Hg(0), or as phenyl-Hg. Sediments were selected to represent a gradient in total Hg concentration, temperature climate, salinity, primary productivity, and organic C content and quality. Most sediments were high in organic matter content due to wood fibre efflux from pulp and paper industry. The pore water was analysed for total Hg, MeHg, DOC, H2S(aq), pH, DOC, Cl and Br. The chemical speciation of Hg(II) and MeHg in pore water was calculated using equilibrium models. Potential methylation and demethylation rates in sediments were determined in incubation experiments at 23° C under N2(g) for 48 h, after addition of isotopically enriched 201Hg(II) and Me204Hg. In all surface (0-20 cm) sediments there was a significant (p<0.001) positive relationship between the experimentally determined specific potential methylation rate constant (Km, day-1) and % MeHg (concentrations of MeHg normalized to total Hg) in the sediment. This indicates that MeHg production overruled degradation and input/output processes of MeHg in surface sediments, and that % MeHg in surface sediments may be used as a proxy for net production of MeHg. To our knowledge, these are the first data showing significant positive relationships between short term (48 h) MeHg production and longer term accumulation of MeHg, across a range of sites with different properties (1). If MeHg was not normalized to total Hg, the relationship was not significant. For sub-sets of brackish waters (p<0.001, n=23), southern, high-productivity freshwaters (p<0.001, n=20) as well as northern, low-productivity freshwater (p=0.048, n=6), the sum of neutral Hg-sulfides [Hg(SH)20 (aq)] and [HgS0 (aq)] in the sediment pore water was significantly, positively correlated with both the potential methylation rate constant (Km) and total MeHg concentrations (2). This indicates that methylating sulphate reducing bacteria passively take up neutral Hg-sulfides, which are transformed to MeHg. Differences in slopes of the relationships were explained by differences in primary productivity and availability of energy-rich organic matter to methylating bacteria. High primary productivity at southern freshwater sites, reflected by a low C/N ratio (large contribution from free living algae and bacteria) in the sediment and a high annual temperature sum, resulted in high methylation rates. In conclusion, concentrations of neutral Hg-sulfides and availability of energy rich organic matter, but also total Hg concentrations in sediments are important factors behind net production and accumulation of MeHg . References: (1) Drott et. al. submitted, (2) Drott, A.; Lambertsson, L.; Björn, E.; Skyllberg, U. Importance of dissolved neutral mercury sulfides for methyl mercury production in contaminated sediments. Environmental Science & Technology 2007, 41, 2270-2276.

  14. Annual variation of total ozone at Syowa Station, Antarctica

    Microsoft Academic Search

    Shigeru Chubachi

    1997-01-01

    Analysis of total ozone data from Syowa (69°S, 40°E) for the years 1982 to 1994 reveals several new features in the behavior of ozone depletion. There is no significant year-to-year trend or seasonal variation of total ozone during the polar night (June and July), and the mean value for these months provides a baseline for determining the springtime ozone decrease.

  15. Annually laminated lake sediments and environmental changes in Bashang Plateau, North China

    Microsoft Academic Search

    Qiumin Zhai; Zhiyong Guo; Yongliang Li; Rongquan Li

    2006-01-01

    Angulinuo Lake is the biggest lake on the Bashang Plateau, North China, and is 47.6 km2 in area and 2–6 m in depth. A core from the inner part of Angulinuo Lake was sliced and the sediment was observed by Scanning Electronic Microscope (SEM). Annual laminations characterized by variable color and grain size were found and interpreted as recording the cyclic deposition

  16. Annual suspended-sediment loads in the Colorado River near Cisco, Utah, 1930-82

    USGS Publications Warehouse

    Thompson, K.R.

    1985-01-01

    The Colorado River upstream of gaging station 09180500 near Cisco, Utah, drains about 24,100 square miles in Utah and Colorado. Altitudes in the basin range from 12,480 feet near the headwaters to 4,090 feet at station 09180500. The average annual precipitation for 1894-1982 near the station was 7.94 inches. The average annual precipitation near the headwaters often exceeds 50 inches. Rocks ranging in age from Precambrian to Holocene are exposed in the drainage basin upstream from station 09180500. Shale, limestone, siltstone, mudstone, and sandstone probably are the most easily eroded rocks in the basin, and they contribute large quantities of sediment to the Colorado River. During 1930-82, the U.S. Geological Survey collected records of fluvial sediment at station 09180500. Based on these records, the mean annual suspended-sediment load was 11,390,000 tone, ranging from 2,038,000 tons in water year 1981 to 35,700,000 tons in water year 1938. The minimum daily load of 14 tons was on August 22, 1960, and the maximum daily load of 2,790,000 tons was on October 14, 1941. (USGS)

  17. Annual suspended-sediment loads in the Green River at Green River, Utah, 1930-82

    USGS Publications Warehouse

    Thompson, K.R.

    1984-01-01

    The Green River above gaging station 093150000 at Green River, Utah, drains about 44,850 square miles in Utah, Colorado, and Wyoming. The average annual precipitation near the station was 6.11 inches. Rocks ranging in age from Precambrian to Holocene are exposed in the Green River drainage basin above Green River, Utah. Shale, siltstone, and mudstone of Tertiary age probably are the most easily eroded rocks in the basin, and they contribute a large part of the sediment load in the Green River. During 1930-82, the U.S. Geological Survey collected records of fluvial sediment at station 093150000. Based on these records the mean annual suspended-sediment load was about 15,630,000 tons, ranging from 1,780,000 tons during 1934 to 43,400,000 tons during 1937. The minimum daily load of 54 tons was on September 27, 1956, and the maximum daily load of 2,230,000 tons was on July 11, 1936. Analysis of the suspended-sediment records collected from 1930-82 at station 093150000 indicated that the accuracy of the records is fair prior to 1945 and good for the remaining period of record. The records after 1945 reflect the use of improved sampling equipment. (USGS)

  18. Total petroleum hydrocarbons in sediments from the coastline and mangroves of the northern Persian Gulf.

    PubMed

    Mohebbi-Nozar, Seyedeh Laili; Zakaria, Mohamad Pauzi; Ismail, Wan Ruslan; Mortazawi, Mohammad Seddiq; Salimizadeh, Maryam; Momeni, Mohammad; Akbarzadeh, Gholamali

    2015-06-15

    To provide baseline information for the marine ecosystem of Hormozgan province, the distribution of petroleum hydrocarbons was evaluated in 52 stations involved in the mangrove and coastline ecosystem. Coastline sampling sites included areas facing harbor, river, domestic and industrial discharge. Sediment samples were analyzed based on ultraviolet fluorescence spectroscopy. Petroleum hydrocarbons showed narrow variations ranging from non-detectable (ND) to 1.71 and from 0.2 to 0.63?g/g dry weight for coastline and mangrove sediments, respectively. The detected concentrations for total petroleum hydrocarbons were lower than guideline values for ecological risk. Furthermore, the minimum environmental risk was confirmed by background levels for the Persian Gulf, the Sea of Oman, and detected values for reference areas. The results were regarded as background data in the studied area, and, considering the rapid expansion of activities related to the petroleum industry in Hormozgan province, the continuous monitoring of pollutants is recommended. PMID:25843439

  19. Macrobenthic community structure and total sediment respiration at cold hydrocarbon seeps in the northern Gulf of Mexico 

    E-print Network

    Nunnally, Clifton Charles

    2004-11-15

    -limited sites on the northern Gulf of Mexico continental slope. Cold seeps were richer in macrofauna densities and total sediment respiration, but were poorer in biomass and taxa diversity than normal slope communities. Decreased diversity is seen at most...

  20. Statistical analysis and estimation of annual suspended sediments of major rivers in Japan.

    PubMed

    Luo, Pingping; He, Bin; Chaffe, Pedro Luiz Borges; Nover, Daniel; Takara, Kaoru; Mohd Remy Rozainy, M A Z

    2013-05-01

    We evaluate the spatiotemporal trends of recent suspended sediment conditions in Japanese rivers. Statistical and spatiotemporal trend analysis is conducted on the 92 major rivers in Japan based on water quality monitoring data from 1992 to 2005. The Mann-Kendall non-parametric method was used to investigate the spatial and temporal trends for the suspended sediment indicator. Results show that the mean concentration of suspended sediments in Japanese rivers has generally declined in recent years, although there are still water quality problems at some monitoring sites (Kanto, Chubu, Kinki and Kyushu regions). A positive relationship between observed yearly discharge and suspended sediment load was found. Land use maps with 100 meter spatial resolution were used to apply an empirical model and develop a regression model for estimating annual suspended sediment loads directly from land use and hydrologic data. Rivers were assigned to three groups according to statistical cluster analysis of suspended sediment (SS) concentration. The correlation between the simulation result from the empirical model and the observed data had R(2) values of 0.62 and 0.71 for groups 2 and 3, and the correlation between the simulation result from the regression model and the observed data had R(2) values of 0.48 and 0.34 for groups 2 and 3. Results show that the proposed simulation technique can be used to predict the pollutant loads to river basins in Japan. Results also suggest prioritization methods and strategies that policy-makers can use to address suspended sediment pollution in rivers and water quality management in general. PMID:23563480

  1. Adjustment of total suspended solids data for use in sediment studies

    USGS Publications Warehouse

    Glysson, G.D.; Gray, J.R.; Conge, L.M.

    2000-01-01

    The U.S. Environmental Protection Agency identifies fluvial sediment as the single most widespread pollutant in the Nation's rivers and streams, affecting aquatic habitat, drinking water treatment processes, and recreational uses of rivers, lakes, and estuaries. A significant amount of suspended-sediment data has been produced using the total suspended solids (TSS) laboratory analysis method. An evaluation of data collected and analyzed by the U.S. Geological Survey and others has shown that the variation in TSS analytical results is considerably larger than that for traditional suspended-sediment concentration analyses (SSC) and that the TSS data show a negative bias when compared to SSC data. This paper presents the initial results of a continuing investigation into the differences between TSS and SSC results. It explores possible relations between these differences and other hydrologic data collected at the same stations. A general equation was developed to relate TSS data to SSC data. However, this general equation is not applicable for data from individual stations. Based on these analyses, there appears to be no simple, straightforward way to relate TSS and SSC data unless pairs of TSS and SSC results are available for a station.

  2. Variability of Total Organic Carbon and Nitrogen in Abyssal Sediments in the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Garcia, F. J.; Escobar Briones, E.

    2007-05-01

    Marine sediments represent the largest reservoir of carbon on Earth and an important factor in climate change and allow us to understand the role of the deep sea sediments as a reservoir for the organic carbon and the chemical balance of nitrogen in the basin. This study determined the precision (CV < 3%) and accuracy (CV < 3%) of the elemental analysis carried out that described the variability of total organic carbon (TOC) and nitrogen from samples collected at 115 locations during several cruises in a depth interval of 1025 and 3725 m. The average values recorded for abyssal sediment samples in the SW Gulf of Mexico were 0.95% +/- 0.135% for TOC and 0.12% +/- 0.025% for N with a C/N ratio of 7.96 +/- 1.406. Only samples from chemosynthetic locations (i.e. Chapopote asphalt volcano) recorded S in 3.35% +/- 1.503%. The elemental composition of TOC and N is controlled by depth and follows a polynomial pattern; the C/N followed a sigmoid pattern and together with TOC varies with the distance to the coast and depth. The presence of topographic features in the seafloor influence the distribution of TOC and N.

  3. Sediment contamination assessment in urban areas based on total suspended solids.

    PubMed

    Rossi, Luca; Chèvre, Nathalie; Fankhauser, Rolf; Margot, Jonas; Curdy, Romuald; Babut, Marc; Barry, D Andrew

    2013-01-01

    Sediment represents an important compartment in surface waters. It constitutes a habitat or spawning site for many organisms and is an essential trophic resource for higher level organisms. It can be impacted by anthropogenic activities, particularly through urban wet-weather discharges like stormwater and combined sewer overflows. An approach was presented for assessing the risks caused by urban wet-weather discharges to the sediment compartment based on total suspended solids (TSS). TSS is routinely measured in field surveys and can be considered as a tracer for urban wet-weather contamination. Three assessment endpoints linked with TSS were proposed: a) siltation of the riverbed, b) oxygen demand due to organic matter degradation and c) accumulation of ecotoxic contaminants on the riverbed (heavy metals, PAHs). These criteria were translated in terms of the maximal TSS accumulation load and exposure time (percentage of time exceeding the accumulation criteria) to account for sediment accumulation dynamics and resuspension in streams impacted by urban wet-weather discharges. These assessment endpoints were implemented in a stochastic model that calculates TSS behavior in receiving waters and allows therefore an assessment of potential impacts. The approach was applied to three Swiss case studies. For each, good agreement was found between the risk predictions and the field measurements confirming the reliability of the approach. PMID:23111128

  4. Distribution of total mercury in surface sediments of the western Jade Bay, Lower Saxonian Wadden Sea, southern North Sea.

    PubMed

    Jin, Huafang; Liebezeit, Gerd; Ziehe, Daniel

    2012-04-01

    A total of 114 surface sediment samples was equidistantly collected in the western part of the Jade Bay, southern North Sea, to analyse total mercury contents as well as grain size distribution and total organic carbon (TOC) contents. Total mercury was determined by oxygen combustion-gold amalgamation. Validation, precision and accuracy of the method were evaluated and controlled with two certified reference materials (HISS-1 and MESS-3). Total mercury contents varied between 8 and 243 ng/g dry sediment with a mean value of 103 ng/g dw. The mercury levels in surface sediments showed an inhomogeneous spatial distribution with higher contents in near-dike areas. The values are mostly in the range of natural background values (50–100 ng/g dw) and positively related to TOC and clay/silt contents (<63 ?m). The present total mercury contents are compared to those of previous studies, in order to estimate possible temporal trends of mercury contents in the study area over the last decades. Moreover, the comparison to sediment quality guidelines indicated that the surface sediments of the Jade Bay are not mercury contaminated. These results also suggested that the current mercury contents of Jade Bay surficial sediments are mostly affected by atmospheric deposition and re-emission. PMID:22301998

  5. Annually laminated lake sediments as recorders of flood events: evidence from combining monitoring and calibration

    NASA Astrophysics Data System (ADS)

    Kämpf, Lucas; Brauer, Achim; Mueller, Philip; Güntner, Andreas; Merz, Bruno

    2015-04-01

    The relation of changing climate and the occurrence of strong flood events has been controversially debated over the last years. One major limitation in this respect is the temporal extension of instrumental flood time series, rarely exceeding 50-100 years, which is too short to reflect the full range of natural climate variability in a region. Therefore, geoarchives are increasingly explored as natural flood recorders far beyond the range of instrumental flood time series. Annually laminated (varved) lake sediments provide particularly valuable archives since (i) lakes form ideal traps in the landscape continuously recording sediment flux from the catchment and (ii) individual flood events are recorded as detrital layers and can be dated with seasonal precision by varve counting. Despite the great potential of varved lake sediments for reconstructing long flood time series, there are still some confinements with respect to their interpretation due to a lack in understanding processes controlling the formation of detrital layers. For this purpose, we investigated the formation of detrital flood layers in Lake Mondsee (Upper Austria) in great detail by monitoring flood-related sediment flux and comparing detrital layers in sub-recent sediments with river runoff data. Sediment flux at the lake bottom was trapped over a three-year period (2011-2013) at two locations in Lake Mondsee, one located 0.9 km off the main inflow (proximal) and one in a more distal position at a distance of 2.8 km. The monitoring data include 26 floods of different amplitude (max. hourly discharge=10-110 cbm/s) which triggered variable fluxes of catchment sediment to the lake floor (4-760 g/(sqm*d)). The comparison of runoff and sediment data revealed empiric runoff thresholds for triggering significant detrital sediment influx to the proximal (20 cbm/s) and distal lake basin (30 cbm/s) and an exponential relation between runoff amplitude and the amount of deposited sediment. A succession of 20 sub-millimetre to maximum 8 mm thick flood-triggered detrital layers, deposited between 1976 and 2005, was detected in two varved surface sediment cores from the same locations as the sediment traps. Calibration of the detrital layer record with river runoff data revealed empirical thresholds for flood layer deposition. These thresholds are higher than those for trapped sediment flux but, similarly to the trap results, increasing from the proximal (50-60 cbm/s; daily mean=40 cbm/s) to the distal lake basin (80 cbm/s, 2 days>40 cbm/s). Three flood events above the threshold for detrital layer formation in the proximal and one in the distal lake basin were also recorded in the monitoring period. These events resulted in exceptional sediment transfer to the lake of more than 400 g/sqm at both sites, which is therefore interpreted as the minimum sediment amount for producing a visible detrital layer.

  6. Assessment of terrigenous organic carbon input to the total organic carbon in sediments from Scottish transitional waters Hydrology and Earth System Sciences, 6(6), 959970 (2002) EGS

    E-print Network

    Paris-Sud XI, Université de

    2002-01-01

    Assessment of terrigenous organic carbon input to the total organic carbon in sediments from of terrigenous organic carbon input to the total organic carbon in sediments from Scottish transitional waters This paper addresses the assessment of terrestrially derived organic carbon in sediments from two Scottish

  7. Predictions of nitrate diffusion in sediment using horizontal attenuated total reflection (HATR) by Fourier transform infrared (FTIR) spectrometry

    Microsoft Academic Search

    H. H. P. Fang; M. Zhang; T. Zhang; J. Chen

    2008-01-01

    Using a novel and simple method based on horizontal attenuated total reflection (HATR) by Fourier transform infrared (FTIR) spectrometry, the effective diffusion coefficient, De, of nitrate in a contaminated anthropogenic sediment was estimated as 7.34×10?6cm2s?1. This method, which requires as little as 1mL of sediment sample, was able to measure the De of a chemical species with a reproducibility of

  8. Siberian regional climate change recorded in annually-laminated lake sediments (Lake Shira, Khakassia, Lake Kucherla, Altai)

    NASA Astrophysics Data System (ADS)

    Darin, Andrey; Kalugin, Ivan; Maksimova, Natalya; Ovchinikov, Dmitrii; Rakshun, Yiakov

    2010-05-01

    During field work in 2009 were sampled cores of bottom sediments of Lake Shira (Khakassia) and Lake Kucherla (Altai). Sediments contain annually laminated layers (varves). The average thickness of layers in the Lake Shira sediments is 1.3 mm, in the Lake Kucherla sediments - 2.3 mm. Cores were impregnated with epoxy resin and then are prepared solid samples thickness of 2 mm for X-ray scan. X-ray scanning was carried out in the Siberian Synchrotron Radiation Center (Budker Institute of nuclear physics SB RAS, Novosibirsk) using the excitation energies of 18 and 24 keV by the methods described in papers [1, 2]. Scanning X-ray fluorescence analysis on synchrotron radiation (SR-XRFA) as a high-efficiency method of microelement analysis is adapted to determine more than 35 elements with minimal step 0.1 mm. A detailed study of the varves with a spatial resolution of 100 microns showed seasonal variation of trace-element composition within the annual layers. It was counting the number of annual layers using the geochemical variations of sediment. Key geochemical indicators of terrigenous (Ti, Ga, Rb, Sr, Zr) and organogenic (Zn, Br, U) components of sediments were identified. Comparison of meteorological data for the past 50 years with the lithological and geochemical parameters of sediments showed a stable dependence of trace-element composition of sediments with the climate variation in the region. Investigated lakes contain high-resolution records of regional climate changes. [1] K.V. Zolotarev et all. Nucl. Instrum. and Meth. A470 (2001),376. [2] A.V. Daryin et all. Nucl. Instrum. and Meth. A 543 (2005) 255.

  9. Features of annual and semiannual variations derived from the global ionospheric maps of total electron content

    Microsoft Academic Search

    B. Zhao; W. Wan; L. Liu; T. Mao; Z. Ren; M. Wang; A. B. Christensen

    2007-01-01

    In the present work we use the NASA-JPL global ionospheric maps of total electron content (TEC), firstly to construct TEC maps (TEC vs. magnetic local time MLT, and magnetic latitude MLAT) in the interval from 1999 to 2005. These TEC maps were, in turn, used to estimate the annual-to-mean amplitude ratio, A1, and the semiannual-to-mean amplitude ratio, A2, as well

  10. Rapid determination of total organic carbon concentration in marine sediments using Fourier transform near-infrared spectroscopy (FT-NIRS)

    Microsoft Academic Search

    Chris J. Leach; Thomas Wagner; Martin Jones; Stephen Juggins; Anthony C. Stevenson

    2008-01-01

    Fourier transform near-infrared spectroscopy (FT-NIRS) together with partial least squares regression was used to produce calibrations between spectra and concentrations of total organic carbon (TOC) in marine sediments collected from widely varying depositional settings. Samples from ODP 664 (oxic Quaternary, low TOC, deep sea ooze) and ODP 959 (anoxic Cretaceous black shale) were analysed using standard instrumental techniques and with

  11. Inter- and intra-annual variability of fluvial sediment transport in the proglacial river Riffler Bach (Weißseeferner, Ötztal Alps, Tyrol)

    NASA Astrophysics Data System (ADS)

    Baewert, Henning; Weber, Martin; Morche, David

    2015-04-01

    The hydrology of a proglacial river is strongly affected by glacier melting. Due to glacier retreat the effects of snow melt and rain storms will become more important in future decades. Additionally, the development of periglacial landscapes will play a more important role in the hydrology of proglacial rivers. The importance of paraglacial sediment sources in sediment budgets of glacier forefields is increasing, while the role of glacial erosion is declining. In two consecutive ablation seasons the fluvial sediment transport of the river Riffler Bach in the Kaunertal (Tyrol/Austria) was quantified. The catchment area of this station is 20 km² with an altitudinal range from 1929 m to 3518 m above msl. The "Weißseeferner" glacier (2.34 km² in 2012) is the greatest of the remaining glaciers. An automatic water sampler (AWS 2002) and a probe for water level were installed were installed at the outlet of the catchment. In order to calculate annual stage-discharge-relations, discharge (Q) was repeatedly measured with current meters. Concurrent to the discharge measurements bed load was collected using a portable Helley-Smith sampler. Bed load (BL) samples were weighted and sieved in the laboratory to gain annual bed load rating curves and grain size distributions. In 2012, 154 water samples were sampled during 7 periods and subsequently filtered to quantify suspended sediment concentrations (SSC). A Q-SSC-relation was calculated for every period due to the high variability in suspended sediment transport. In addition, the grain size distribution of the filtered material was determined by laser diffraction analysis. In 2013, the same procedure was performed for 232 water samples which were collected during 9 periods. Meteorological data were logged at the climate station "Weißsee", which is located in the centre of the study area. First results show a high variability of discharge and solid sediment transport both at the inter-annual as well as at the intra-annual timescale. In 2012, a larger amount of sediment was transported compared to 2013. A higher runoff during the snowmelt period 2012 and a heavy rain fall event in late August 2012 were the main reasons. Only 8 of 16 Q-SSC-relations show causal dependency. Thus, indicating that sediment transport strongly depends on the availability of sediment and the coupling of sediment sources to the fluvial system.

  12. Statistic analysis of annual total ozone extremes for the period 1964-1988

    NASA Technical Reports Server (NTRS)

    Krzyscin, Janusz W.

    1994-01-01

    Annual extremes of total column amount of ozone (in the period 1964-1988) from a network of 29 Dobson stations have been examined using the extreme value analysis. The extremes have been calculated as the highest deviation of daily mean total ozone from its long-term monthly mean, normalized by the monthly standard deviations. The extremes have been selected from the direct-Sun total ozone observations only. The extremes resulting from abrupt changes in ozone (day to day changes greater than 20 percent) have not been considered. The ordered extremes (maxima in ascending way, minima in descending way) have been fitted to one of three forms of the Fisher-Tippet extreme value distribution by the nonlinear least square method (Levenberg-Marguard method). We have found that the ordered extremes from a majority of Dobson stations lie close to Fisher-Tippet type III. The extreme value analysis of the composite annual extremes (combined from averages of the annual extremes selected at individual stations) has shown that the composite maxima are fitted by the Fisher-Tippet type III and the composite minima by the Fisher-Tippet type I. The difference between the Fisher-Tippet types of the composite extremes seems to be related to the ozone downward trend. Extreme value prognoses for the period 1964-2014 (derived from the data taken at: all analyzed stations, the North American, and the European stations) have revealed that the prognostic extremes are close to the largest annual extremes in the period 1964-1988 and there are only small regional differences in the prognoses.

  13. Anomalous South Pacific lithosphere dynamics derived from new total sediment thickness estimates off the West Antarctic margin

    NASA Astrophysics Data System (ADS)

    Wobbe, Florian; Lindeque, Ansa; Gohl, Karsten

    2014-12-01

    Paleotopographic models of the West Antarctic margin, which are essential for robust simulations of paleoclimate scenarios, lack information on sediment thickness and geodynamic conditions, resulting in large uncertainties. A new total sediment thickness grid spanning the Ross Sea-Amundsen Sea-Bellingshausen Sea basins is presented and is based on all the available seismic reflection, borehole, and gravity modeling data offshore West Antarctica. This grid was combined with NGDC's global 5 arc minute grid of ocean sediment thickness (Whittaker et al., 2013) and extends the NGDC grid further to the south. Sediment thickness along the West Antarctic margin tends to be 3-4 km larger than previously assumed. The sediment volume in the Bellingshausen, Amundsen, and Ross Sea basins amounts to 3.61, 3.58, and 2.78 million km3, respectively. The residual basement topography of the South Pacific has been revised and the new data show an asymmetric trend over the Pacific-Antarctic Ridge. Values are anomalously high south of the spreading ridge and in the Ross Sea area, where the topography seems to be affected by persistent mantle processes. In contrast, the basement topography offshore Marie Byrd Land cannot be attributed to dynamic topography, but rather to crustal thickening due to intraplate volcanism. Present-day dynamic topography models disagree with the presented revised basement topography of the South Pacific, rendering paleotopographic reconstructions with such a limited dataset still fairly uncertain.

  14. Toxic elements at a disused mine district: Particle size distribution and total concentration in stream sediments and mine tailings.

    PubMed

    Giuliano, V; Pagnanelli, F; Bornoroni, L; Toro, L; Abbruzzese, C

    2007-09-01

    Heavy metal and metalloid pollution at a disused pyrite mine was investigated. Five solid samples collected in the area (three stream sediments with different soil texture, a background soil sample and a mine tailing) were characterised by mineral and element composition, particle size distribution (by wet and dry sieving and laser diffraction) and total concentration by acid digestion (Mn, Zn, Cu, Pb, Hg, Cd, Sb and As). X-ray and element analyses denoted a common mineralogical and chemical composition of mainly quartz, clinochlore, muscovite, anorthite, and hematite. Particle size distributions of the five samples showed that stream sediments were characterised by larger percentage of sand range classes (2000-60 microm) while background sample and tailing are mainly characterised by gravel particles (>2000 microm). Wet and dry sieving procedures gave different particle size distributions, which can be interpreted by laser diffraction analysis and represented by Rosin-Rammler model. Concentrations of Zn, Cu and Cd were higher in the stream sediments than the tailing and background soil, while Mn, As, Sb and Hg are mainly concentrated in the tailing sample. Metal concentrations in the three stream sediment samples are correlated with both particle size dimensions (D(63.2)) and concentration of geochemical normalizers (iron and aluminium). These correlations are observed also for the pollutants that are mainly concentrated in tailing sample (Mn and As), denoting the importance of surface interactions also for the binding of these elements onto stream sediments. PMID:17400373

  15. Resuspended contaminated sediments cause sublethal stress to oysters: A biomarker differentiates total suspended solids and contaminant effects.

    PubMed

    Edge, Katelyn J; Dafforn, Katherine A; Simpson, Stuart L; Ringwood, Amy H; Johnston, Emma L

    2015-06-01

    Resuspended contaminated sediments represent an important route of contaminant exposure for aquatic organisms. During resuspension events, filter-feeding organisms are exposed to contaminants, in both the dissolved form (at the gills) and the particulate form (in the digestive system). In addition, these organisms must manage the physical stress associated with an increase in total suspended solids (TSS). To date, few studies have experimentally compared the contributions to biological stress of contaminated and clean suspended solids. The authors mixed field-collected sediments (<63??m) from clean and contaminated field sites to create 4 treatments of increasing metal concentrations. Sydney rock oysters were then exposed to sediment treatments at different TSS concentrations for 4 d, and cellular biomarkers (lysosomal membrane stability, lipid peroxidation, and glutathione) were measured to evaluate sublethal toxicity. Lysosomal membrane stability was the most sensitive biomarker for distinguishing effects from resuspended contaminated sediments, as increasing amounts of contaminated TSS increased lysosomal membrane destabilization. The authors' results illustrate the importance of considering contaminant exposures from resuspended sediments when assessing the toxicity of contaminants to aquatic organisms. Environ Toxicol Chem 2015;34:1345-1353. © 2015 SETAC. PMID:25677686

  16. Measuring total longshore sediment transport with a LISST instrumented mini-sled. 

    E-print Network

    Huchzermeyer, Erick Karl

    2006-04-12

    A surf zone sediment transport study was conducted in Jamaica Beach, Texas, using new oceanographic equipment. A mini-sled was constructed and outfitted with an instrument package that consisted of two velocimeters, one current profiler, three OBS...

  17. 76 FR 3142 - Notice of Annual Adjustment of the Cap on Average Total Assets That Defines Community Financial...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-19

    ...2011-N-01] Notice of Annual Adjustment of the Cap on Average Total Assets That Defines Community...Finance Agency (FHFA) has adjusted the cap on average total assets that defines a...has average total assets below a statutory cap. See 12 U.S.C....

  18. 78 FR 19262 - Notice of Annual Adjustment of the Cap on Average Total Assets That Defines Community Financial...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-29

    ...2013-N-04] Notice of Annual Adjustment of the Cap on Average Total Assets That Defines Community...Finance Agency (FHFA) has adjusted the cap on average total assets that defines a...has average total assets below a statutory cap.\\2\\ The Bank Act was amended in...

  19. 75 FR 9601 - Notice of Annual Adjustment of the Cap on Average Total Assets That Defines Community Financial...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-03

    ...2010-N-01] Notice of Annual Adjustment of the Cap on Average Total Assets That Defines Community...Finance Agency (FHFA) has adjusted the cap on average total assets that defines a...has average total assets below a statutory cap. See 12 U.S.C....

  20. 77 FR 14366 - Notice of Annual Adjustment of the Cap on Average Total Assets That Defines Community Financial...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-09

    ...2012-N-02] Notice of Annual Adjustment of the Cap on Average Total Assets That Defines Community...Finance Agency (FHFA) has adjusted the cap on average total assets that defines a...has average total assets below a statutory cap.\\2\\ The Bank Act was amended in...

  1. Evaluation of an interlaboratory proficiency-testing exercise for total mercury in environmental samples of soils, sediments and fish tissue

    Microsoft Academic Search

    R. Rocha; S RODRIGUES; M OTERO; M VALEGA; C LOPES; P PATO; J COELHO; A LILLEBO; A DUARTE; M PARDAL

    2008-01-01

    A proficiency-testing scheme concerning total mercury determination in soils and sediments (with different levels of contamination) and fish tissue involved 25 European laboratories as participants, who used their regular in-house analytical methods, and reference values were determined from the results obtained. The most precise results were obtained for the fish matrix. The majority of participants obtained satisfactory Z-scores, and laboratories

  2. Geospatial analysis of spatiotemporal patterns of pH, total suspended sediment and chlorophyll- a on the Amazon floodplain

    Microsoft Academic Search

    Cláudio Clemente Faria Barbosa; Evlyn Márcia Leão de Moraes Novo; John M. Melack; Mary Gastil-Buhl; Waterloo Pereira Filho

    2010-01-01

    We applied spatial data analysis and geostatistical procedures to pH, total suspended sediment and chlorophyll-a concentration data gathered on an Amazon floodplain lake. Variographic analysis and ordinary kriging interpolation were used\\u000a to identify and describe spatiotemporal patterns of variability in these parameters, which are relevant to understand the\\u000a dynamics of water circulation on the floodplain lake. In spite of the

  3. Suspended-sediment and suspended-sand concentrations and loads for selected streams in the Mississippi River Basin, 1940-2009

    USGS Publications Warehouse

    Heimann, David C.; Cline, Teri L.; Glaspie, Lori M.

    2011-01-01

    This report presents suspended-sediment concentration and streamflow data, describes load-estimation techniques used in the computation of annual suspended-sediment loads, and presents annual suspended-sediment loads for 48 streamgaging stations within the Mississippi River Basin. Available published, unpublished, and computed annual total suspended-sediment and suspended-sand loads are presented for water years 1940 through 2009. When previously published annual loads were not available, total suspended-sediment and sand loads were computed using available data for water years 1949 through 2009. A table of suspended-sediment concentration and daily mean streamflow data used in the computation of annual loads is presented along with a table of compiled and computed annual suspended-sediment and suspended-sand loads, annual streamflows, and flow-weighted concentrations for the 48 stations.

  4. Estimation of suspended-sediment concentration from total suspended solids and turbidity data for Kentucky, 1978-1995

    USGS Publications Warehouse

    Williamson, T.N.; Crawford, C.G.

    2011-01-01

    Suspended sediment is a constituent of water quality that is monitored because of concerns about accelerated erosion, nonpoint contamination of water resources, and degradation of aquatic environments. In order to quantify the relationship among different sediment parameters for Kentucky streams, long-term records were obtained from the National Water Information System of the U.S. Geological Survey. Suspended-sediment concentration (SSC), the parameter traditionally measured and reported by the U.S. Geological Survey, was statistically compared to turbidity and total suspended solids (TSS), two parameters that are considered surrogate data. A linear regression of log-transformed observations was used to estimate SSC from TSS; 72% of TSS observations were less than coincident SSC observations; however, the estimated SSC values were almost as likely to be overestimated as underestimated. The SSC-turbidity relationship also used log-transformed observations, but required a nonlinear, breakpoint regression that separated turbidity observations ???6nephelometric turbidity units. The slope for these low turbidity values was not significantly different than zero, indicating that low turbidity observations provide no real information about SSC; in the case of the Kentucky sediment record, this accounts for 30% of the turbidity observations. ?? 2011 American Water Resources Association. This article is a U.S. Government work and is in the public domain in the USA.

  5. Late Quaternary environmental and climatic changes in central Europe as inferred from the composition of organic matter in annually laminated maar lake sediments

    Microsoft Academic Search

    Andreas Fuhrmann; Thomas Fischer; Andreas Lücke; Achim Brauer; Bernd Zolitschka; Brian Horsfield; Jörg F. W. Negendank; Gerhard H. Schleser; Heinz Wilkes

    2004-01-01

    Geochemical (elemental analysis, bulk ?13CTOC, thermal degradation techniques, molecular analysis of n-alkanes) and microscopic investigations (maceral analysis, vitrinite reflectance) were performed (1) to characterize the organic matter (OM) in sediments from two maar lakes in the Westeifel volcanic field, Germany, and (2) to discuss paleoenvironmental processes which have controlled the accumulation and preservation of OM. The annually laminated sediments show

  6. NUTRIENT AND SEDIMENT TOTAL MAXIMUM DAILY LOADS FOR FIVE NORTH DAKOTA RESERVOIRS

    EPA Science Inventory

    Five North Dakota reservoirs will be target for the development of a sediment nutrient TMDL. For each TMDL, a project specific QAPP will be developed. As part of each TMDL, field sampling will include tributary discharge and chemical sampling, lake sampling, and the development...

  7. Differentiation between bioavailable and total hazard potential of sediment-induced DNA fragmentation as measured by the comet assay with Zebrafish embryos

    Microsoft Academic Search

    Thomas Kosmehl; Falk Krebs; Werner Manz; Thomas Braunbeck; Henner Hollert

    2007-01-01

    Goals, Scope and Background  While water quality strongly improved over decades in the Rhine River, sediments still reflect elapsed contaminations of organic\\u000a pollutants and heavy metals. In comparing genotoxic effects induced by both sediment extracts and whole sediments, a ratio\\u000a of bioavailable toxicity and total extractable toxicity is obtained. Since contaminated sites whose contaminants are toxic\\u000a and as well bioavailable present

  8. An evaluation of 14C age relationships between co-occurring foraminifera, alkenones, and total organic carbon in continental margin sediments

    Microsoft Academic Search

    Gesine Mollenhauer; Markus Kienast; Frank Lamy; Helge Meggers; Ralph R. Schneider; John M. Hayes; Timothy I. Eglinton

    2005-01-01

    Radiocarbon age relationships between co-occurring planktic foraminifera, alkenones, and total organic carbon in sediments from the continental margins of southern Chile, northwest Africa, and the South China Sea were compared with published results from the Namibian margin. Age relationships between the sediment components are site-specific and relatively constant over time. Similar to the Namibian slope, where alkenones have been reported

  9. Bacterial numbers and growth in surficial deep-sea sediments and phytodetritus in the NE Atlantic: Relationships with particulate organic carbon and total nitrogen

    Microsoft Academic Search

    C. M. Turley; J. L. Dixon

    2002-01-01

    Bacteria in deep-sea sediments constitute the largest global fraction of total benthic bacteria, and play a major role in most biogeochemical cycles. However, as yet the relationship between bacterial production and substrate availability (particulate organic carbon and nitrogen) in deep-sea sediments is not well understood. Therefore the aim of this study was to explore the relationships between bacterial numbers and

  10. A thermo extraction-UV/Vis spectrophotometric method for total iodine quantification in soils and sediments.

    PubMed

    Gilfedder, B S; Althoff, F; Petri, M; Biester, H

    2007-12-01

    Iodine in soils and sediments is a difficult element to analyze due to its volatility in acidic conditions. Traditionally it has been quantified using neutron activation analysis techniques, which, unfortunately, requires access to a nuclear reactor. We present here a simple method for solid-phase iodine analysis by thermo extraction at 1000 degrees C and quantification by UV/Vis photometry. Samples are combusted in an oxygen stream and trapped in Milli-Q water. The extracts are then quantified by an As3+-Ce4+ spectrometric method whereby iodide catalyzes the oxidation of As3+ to As5+ and reduction of Ce4+ to Ce3+. Three standard reference materials were analyzed with excellent recoveries (97-113%) and RSDs (<5%). Moreover, the detection limit was less than 50 ng absolute iodine with a confidence limit of 95%. When applied to carbonate-rich samples from sediment traps deployed in Lake Constance we found very low iodine levels (0.8-2 mg kg(-1)). Despite the low concentrations, the precision of the method was consistently better than 5% RSD. However, the method needed to be slightly modified for organic and iodine-rich sediments (20-30% organic carbon) from a lake in the Black Forest by increasing the oxygen flow rate and decreasing the combustion time. Using the modified method we were able to achieve RSDs lower than 5%. PMID:17924101

  11. Longitudinal dependence of annual cycle of total ozone in the Northern mid-latitudes

    NASA Astrophysics Data System (ADS)

    Milinevsky, Gennadi; Evtushevsky, Oleksandr; Grytsai, Asen

    2015-04-01

    In the Northern mid-latitudes, annual change of the total ozone content (TOC) in terms of zonal means is mainly determined by stratospheric ozone accumulation in winter and spring due to the Brewer-Dobson circulation (BDC) and following photochemical relaxation continuing to autumn. It is known from previous studies that annual TOC cycle in some regions could be close to or differ from the zonal mean one. For example, annual TOC minimum over Eastern Asia is observed two months earlier (August) than over Europe (October). In this work, a consecutive analysis of the TOC seasonality along the latitudinal belt 50-55°N in 36 segments (10°-step in longitude) is analyzed. The latitude range includes northern Ukraine and Kyiv-Goloseyev Dobson station. Analysis is based on the Merged Ozone Data Set (MOD) reanalysis 1979-2011 (http://acd-ext.gsfc.nasa.gov/Data_services/merged/). We use also the NCEP-NCAR reanalysis data (http://www.esrl.noaa.gov/psd/cgi-bin/data/composites/printpage.pl) to estimate seasonal changes in geopotential heights and tropopause heights. It is shown that the seasonal TOC cycle over the cyclonic anomalies (high mean TOC level) is shifted to the beginning of year in comparison with that over the anticyclonic anomalies (low mean TOC level). The largest TOC values over the Aleutian low (around 150°E) are characterized by the earliest seasonal maximum (February-March) and minimum (August). Here, the tropospheric dynamics (winter/summer extremes in the planetary wave activity and stationary pressure anomaly formation/disappearance) and related tropopause effects seem to have dominant influence on the earliest development of the annual TOC cycle. Zonal asymmetry in stratospheric ozone accumulation influences rather the maximum TOC levels in this region than timing of the TOC extremes. In the opposite longitude range (zonal TOC minimum in region of the Azores high influence, 20-30°W), the annual TOC cycle lags by 2-3 months reaching a TOC maximum in May and a TOC minimum in November. Seasonal changes in this subtropical anomaly (pressure and tropopause height) are weak. Hence, troposphere influence on the TOC seasonality here is small in comparison with Aleutian low region. Slow accumulation of the stratospheric ozone during winter and spring leads to the latest occurrence of seasonal TOC maximum. Photochemical ozone relaxation lasts also longer up to beginning of the next BDC intensification since December. The results of this analysis could be useful for explanation of the interannual variations in the local annual TOC cycles considering the climatological ones in neighboring segments of the northern midlatitudes. Possible effects of the TOC seasonality in regional climate changes could also be analyzed in future studies. Acknowledgments. This work was partly supported by the Polar FORCeS project no. 4012 of the Australian Antarctic Science Program.

  12. Monitoring Fine Sediment; Grande Ronde and John Day Rivers, 1998 Annual Report.

    SciTech Connect

    Purser, Michael D.; Rhodes, Jonathan J.

    1999-01-01

    Fine sediment levels in spawning substrate have a major effect on salmon survival from egg to smolt. Assessments have consistently concluded that fine sediment is a major problem for salmon in the Grande Ronde and, to a lesser extent, the John Day rivers. It is likely that fine sediment levels in these rivers must be reduced if salmon survival from egg to smolt is to be increased.

  13. Summary Report of the Seventh Annual NASA/Contractors Conference on Quality and Productivity: "Total Quality Leadership"

    NASA Technical Reports Server (NTRS)

    1991-01-01

    More than 750 NASA, government, contractor, and academic representatives attended the Seventh Annual NASA/Contractors Conference on Quality and Productivity on October 12-13, 1990, in Grenelefe, Florida. The panel presentations and keynote speeches revolving around the theme of 'Total Quality Leadership" provided a solid base of understanding of the importance, benefits, and principles of total quality management. The implementation of these strategies is critical if we are to effectively pursue our mission of continuous quality improvement and reliability in our products, processes, and services. The annual NASA/contractors conferences serve as catalysts for achieving success in this mission.

  14. The mineral magnetic properties of an annually laminated Holocene lake-sediment sequence in northern Sweden

    Microsoft Academic Search

    Ian Snowball; Per Sandgren; Gunilla Petterson

    1999-01-01

    Detailed mineral magnetic measurements were conducted on a 9000-year varved lake sediment sequence in northern Sweden (Lake Sarsjön). The results demonstrate that the paramagnetic susceptibility reflects the concentration of detrital minerogenic material in the lake sediments, which is controlled to a large extent by the intensity of the spring snow melt. In contrast, the concentration of ferrimagnetic magnetite (reflected by

  15. Annual and semiannual variations of vertical total electron content during high solar activity based on GPS observations

    Microsoft Academic Search

    M. P. Natali; A. Meza

    2011-01-01

    Annual, semiannual and seasonal variations of the Vertical Total Electron Content (VTEC) have been investigated during high solar activity in 2000. In this work we use Global IGS VTEC maps and Principal Component Analysis to study spatial and temporal ionospheric variability. The behavior of VTEC variations at two-hour periods, at noon and at night is analyzed. Particular characteristics associated with

  16. Impact of dams on Yangtze River sediment supply to the sea and delta intertidal wetland response

    Microsoft Academic Search

    S. L. Yang; J. Zhang; J. Zhu; J. P. Smith; S. B. Dai; A. Gao; P. Li

    2005-01-01

    On the basis of estimates of sediment accumulation in reservoirs, the impact of 50,000 dams on sediment supply and intertidal wetland response in the Yangtze River catchment is examined. The total storage capacity of reservoirs is 200 × 109 m3, or 22% of the Yangtze annual runoff. The sediment accumulation rate in reservoirs has increased from ?0 in 1950 to

  17. Paonia Reservoir Sediment Management

    NASA Astrophysics Data System (ADS)

    Kimbrel, S.; Collins, K.; Williams, C.

    2014-12-01

    Paonia Dam and Reservoir are located on Muddy Creek, a tributary of the North Fork Gunnison River in western Colorado. Since dam closure in 1962, the 2002 survey estimates an annual sedimentation rate of 153,000 m3/y, resulting in a 25% loss of total reservoir capacity. Long before sediment levels completely fill the reservoir, the outlet works have recently plugged with sediment and debris, adversely impacting operations, and emphasizing the urgency of formulating an effective sediment management plan. Starting in 2010-2011, operations were changed to lower the reservoir and flush sediment through the outlet works in early spring before filling the pool for irrigation. Even though the flushing strategy through the long, narrow reservoir (~5 km long and 0.3 km wide) has prevented outlet works plugging, a long term plan is needed to manage inflowing and deposited sediment more efficiently. Reclamation's Sedimentation and River Hydraulics Group is leading an effort to study the past and current sediment issues at Paonia Dam and Reservoir, evaluate feasible sediment management alternatives, and formulate a plan for future operations and monitoring. The study is building on previously collected data and the existing knowledge base to develop a comprehensive, sustainable sediment management plan. The study is being executed in three phases: Phase 1 consisted of an initial site visit to map and sample existing reservoir bottom sediments, a preliminary site evaluation upstream and downstream of the dam, and establishment of time-lapse photo sites and taking initial ground-based photos. Phase 2 includes a bathymetric survey of entire reservoir and 11 km of the river downstream of the dam, continuous suspended sediment monitoring upstream and downstream of the reservoir, and collection of additional core samples of reservoir bottom sediments. Phase 3 involves the evaluation of current and past operations and sediment management practices, evaluate feasible sediment management methods, and providing recommendations for future monitoring and sediment management operations. Data collected during Phases 1 and 2 are used in a one-dimensional numerical sediment transport model for evaluating past, current, and potential future sediment management options.

  18. Diatoms (Class Bacillariophyceae) and geochemistry from annually laminated mid-Holocene sediments, west coast Canada: insights into abrupt climate change in the past

    Microsoft Academic Search

    A. Chang; T. F. Pedersen

    2009-01-01

    A 115-year record of annually laminated sediments from Effingham Inlet, a small anoxic fjord on the west coast of Vancouver Island, British Columbia (49˚N, 125˚W), was analyzed for diatoms (species and abundances) and geochemistry (C and N isotopes, organic C and trace elements Ag, Cd, Re and Mo) from a piston core. The sediments were radiocarbon dated at approx. 4200-4400

  19. 24 CFR 884.104 - Maximum total annual contract commitment and project account (private-owner or PHA-owner projects).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...annual contract commitment and project account (private-owner or PHA-owner projects). 884.104 Section 884.104 Housing...annual contract commitment and project account (private-owner or PHA-owner projects). (a) Maximum total annual contract...

  20. 24 CFR 884.104 - Maximum total annual contract commitment and project account (private-owner or PHA-owner projects).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...annual contract commitment and project account (private-owner or PHA-owner projects). 884.104 Section 884.104 Housing...annual contract commitment and project account (private-owner or PHA-owner projects). (a) Maximum total annual contract...

  1. 24 CFR 884.104 - Maximum total annual contract commitment and project account (private-owner or PHA-owner projects).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...annual contract commitment and project account (private-owner or PHA-owner projects). 884.104 Section 884.104 Housing...annual contract commitment and project account (private-owner or PHA-owner projects). (a) Maximum total annual contract...

  2. 77 FR 62396 - Annual Company-Run Stress Test Requirements for Banking Organizations With Total Consolidated...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-12

    ...7100-AD-86 Annual Company-Run Stress Test Requirements for Banking Organizations...financial regulatory agency to conduct stress tests on an annual basis. The Board is adopting...rule to implement the company-run stress test requirements in the Dodd-Frank Act...

  3. Stable isotope record in annually laminated lake sediments from Lake ?abi?skie (NE Poland) for the last millennium.

    NASA Astrophysics Data System (ADS)

    Gabry?, Alicja; Piotrowska, Natalia; Tylmann, Wojciech; Bonk, Alicja; Filipiak, Janusz; Wacnik, Agnieszka; Hernandez-Almeida, Ivan; Grosjean, Martin

    2015-04-01

    Stable isotope record of carbon (13C) and oxygen (18O) has been analysed from an annually laminated sediment from Lake Zabinskie (Mazurian Lakeland, NE Poland) with high resolution (1-3 yrs). The sediment layers which were formed in each year during the last millennium contain information about environmental changes in the past. The calcite layers are formed in lake sediment in warm months of the year, therefore the reconstruction of summer climate variables in the past is potentially possible. The investigation of correlation between isotope dataset and instrumental climate data for years 1897-2008 AD confirmed that theory. The record of temperature, precipitation and SPEI (Standardised Precipitation Evaporation Index) coefficient, which is a combination of both temperature and precipitation, was tested. The strongest linear correlations were found for most samples for June, July, August (JJA) months but in some cases the correlation coefficient was stronger when also May was taken into account. For the whole 120-yrs series the correlation between ?18O and average JJA temperature is 0.007, average JJA precipitation is 0.16 and average JJA SPEI is 0.20. Analyzing the results for 1897-2008 we can distinguish period 1960-2008 with relevantly stronger correlations: R(temperature) = 0.19, R(precipitation) = 0.20 and R(SPEI) = 0.45. This period is connected with cessation of human activity close to Lake Zabinskie. Reconstruction of climate variables for the last millennium was made using transfer function obtained for calibration period (1897-2008). Reconstructions showed that known climate extremes like Medieval Warm Period, Little Ice Age with Sporer (1420-1570), Maunder (1645-1715) and Dalton (1790-1820) Minimum was recorded in sediment from Lake Zabinskie. The presented study is a part of the project "Climate of northern Poland during the last 1000 years: Constraining the future with the past (CLIMPOL)", funded within Polish-Swiss Research Programme. http://www.climpol.ug.edu.pl

  4. Organic matter diagenesis in freshwater sediments: The alkalinity and total CO2 balance and methane production in the sediments of Lake Washington

    Microsoft Academic Search

    KATHRYN M. KUIVILA; JAMES W. MURRAY

    1984-01-01

    The interstitial water chemistry of Lake Washington sediments collected with an in situ sampler was studied. The depth where the sulfate concentration reaches a low background value appears to delineate a transition within the sediments above and below which profiles oftotal C02, alkalinity, methane, and ammonium are linear, suggesting zones dominated by diffusion separated by a narrow zone of reaction.

  5. Mineralogy-based quantitative precipitation and temperature reconstructions from annually laminated lake sediments (Swiss Alps) since AD 1580

    NASA Astrophysics Data System (ADS)

    Trachsel, M.; Eggenberger, U.; Grosjean, M.; Blass, A.; Sturm, M.

    2008-07-01

    We present quantitative autumn, summer and annual precipitation and summer temperature reconstructions from proglacial annually laminated Lake Silvaplana, eastern Swiss Alps back to AD 1580. We used X-ray diffraction peak intensity ratios of minerals in the sediment layers (quartz qz, plagioclase pl, amphibole am, mica mi) that are diagnostic for different source areas and hydro-meteorological transport processes in the catchment. XRD data were calibrated with meteorological data (AD 1800/1864-1950) and revealed significant correlations: mi/pl with SON precipitation (r = 0.56, p < 0.05) and MJJAS precipitation (r = 0.66, p < 0.01); qz/mi with MJJAS temperature (r = -0.72, p < 0.01)and qz/am with annual precipitation (r = -0.54, p < 0.05). Geological catchment settings and hydro-meteorological processes provide deterministic explanations for the correlations. Our summer temperature reconstruction reproduces the typical features of past climate variability known from independent data sets. The precipitation reconstructions show a LIA climate moister than today. Exceptionally wet periods in our reconstruction coincide with regional glacier advances.

  6. ANNUAL REPORT. THE INFLUENCE OF CALCIUM CARBONATE GRAIN COATINGS ON CONTAMINANT REACTIVITY IN VADOSE ZONE SEDIMENTS

    EPA Science Inventory

    The primary objective of this project is to investigate the role of calcium carbonate grain coatings on adsorption and heterogeneous reduction reactions of key chemical and radioactive contaminants in sediments on the Hanford Site. Research will ascertain whether these coatings p...

  7. High-resolution past environmental reconstruction in East Asia using annually laminated lake sediments of Lake Megata in northeastern Japan

    NASA Astrophysics Data System (ADS)

    Yamada, K.; Gotanda, K.; Yonenobu, H.; Shinozuka, Y.; Kitagawa, J.; Makohonienko, M.; Schwab, M.; Haraguchi, T.; Yasuda, Y.

    2007-12-01

    37 m-long non-glacial varved sequences were taken from Ichi-no-Megata maar in Oga Peninsula, Akita, northern part of Japan. Ichi-no-Megata maar occupies 0.25 km2 with a maximum water depth of ca. 45.1 m. The shape of lake is a kettle-type basin and the deepest bottom basin is very flat. We took core samples (named IMG06 core) at the center of the lake in November to December in 2006. In order to take completely continuous maar sediment, we drilled three holes and take every sample from each hole which apart only few meters. In this drilling campaign, we can 37 m-long continuous maar sediment except thick volcanic deposits from 26.5 to 31.7m in core. The sedimentological feature of IMG06 core is dominated by thin lamination clay/silt from most top part up to 37 m with turbidites characterized upward fining structure. The SEM image observation of lamination reveals that sponge-like lamina consists of diatom assemblage against dark colored lamina consists of mixture of detritus minerals, clay minerals, and diatom. It means sponge-like lamina deposits during spring season, and later one deposits during another three seasons, and then these thin lamination of IMG06 core could be identified as annual lamination (varves). This interpretation is supported by the correlation of historic event as earthquake and tunnel construction. In this IMG06 core, six volcanic ashes are found and we have also analyzed radiocarbon dating from 38 horizons of the core to use leaf and seeds inter-bedded varves. As the results, the IMG06 core covers from 25,000 to 4,000 14C yr BP with stable sedimentation rates (0.71mm/year).

  8. Runoff losses of suspended sediment, nitrogen, and phosphorus from a small watershed in Korea

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objectives of this study were to develop annual and seasonal load-discharge relationships for Suspended Sediment (SS), Total Nitrogen (TN), and Total Phosphorus (TP) losses in runoff from a small mixed land use watershed, and to use these relationships to explicate the annual and monthly pattern...

  9. 24 CFR 884.104 - Maximum total annual contract commitment and project account (private-owner or PHA-owner projects).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...Maximum total annual contract commitment and project account (private-owner or PHA-owner projects). 884.104 Section 884.104 Housing...SET-ASIDE FOR SECTION 515 RURAL RENTAL HOUSING PROJECTS Applicability, Scope and Basic...

  10. 24 CFR 884.104 - Maximum total annual contract commitment and project account (private-owner or PHA-owner projects).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...Maximum total annual contract commitment and project account (private-owner or PHA-owner projects). 884.104 Section 884.104 Housing...SET-ASIDE FOR SECTION 515 RURAL RENTAL HOUSING PROJECTS Applicability, Scope and Basic...

  11. Recruitment of Total Phytoplankton, Chlorophytes and Cyanobacteria from Lake Sediments Recorded by Photosynthetic Pigments in a Large, Shallow Lake (Lake Taihu, China)

    NASA Astrophysics Data System (ADS)

    Cao, Huan-Sheng; Kong, Fan-Xiang; Tan, Jian-Kang; Zhang, Xiao-Feng; Tao, Yi; Yang, Zhou

    2005-08-01

    Recruitment of total phytoplankton, chlorophytes and cyanobacteria from lake sediments to the water column was studied using photosynthetic pigments at one site (1.5 m) in Lake Taihu, a large shallow lake in China. Samples were taken weekly from the migration traps installed on the bottom from March to May 2004. Abundance of total phytoplankton, chlorophytes and cyanobacteria were represented by Chlorophyll (Chl) a, b, and phycocyanin (PC), respectively. Over the three months, total phytoplankton, chlorophytes, and cyanobacteria corresponding to 48.9%, 68.9% and 316.2% of their initial concentrations in surface sediments were recruited in Lake Taihu. However, compared with their increase in pelagic abundance over the same period, the recruitment accounted for a rather small inoculum. Accompanying the recruitment, total phytoplankton and chlorophytes declined and cyanobacteria increased in the upper 0-2 cm sediments; colonies of Microcystis aeruginosa in the water column enlarged from small size with several cells to large colonies with hundreds of cells. Thus, overwintering and subsequent growth renewal of pelagic phytoplankton merits further study and comparison with benthic survival and recruitment.

  12. Determination of Total Free Sulphides in Sediment Porewater and Artefacts Related to the Mobility of Mineral Sulphides

    Microsoft Academic Search

    Kristina A. BrownEric; Eric R. McGreer; Bernie Taekema; Jay T. Cullen

    A field and laboratory study of the accuracy of a method commonly used to determine free sulphide concentrations in the porewater\\u000a of marine sediments is presented. The method uses an ion-selective electrode (ISE), sensitive to the sulphide ion (S2?), in sediments buffered to high pH (>12) and is commonly used in regulatory monitoring programs to assess the impacts of\\u000a open

  13. A doubling of microphytobenthos biomass coincides with a tenfold increase in denitrifier and total bacterial abundances in intertidal sediments of a temperate estuary.

    PubMed

    Decleyre, Helen; Heylen, Kim; Sabbe, Koen; Tytgat, Bjorn; Deforce, Dieter; Van Nieuwerburgh, Filip; Van Colen, Carl; Willems, Anne

    2015-01-01

    Surface sediments are important systems for the removal of anthropogenically derived inorganic nitrogen in estuaries. They are often characterized by the presence of a microphytobenthos (MPB) biofilm, which can impact bacterial communities in underlying sediments for example by secretion of extracellular polymeric substances (EPS) and competition for nutrients (including nitrogen). Pyrosequencing and qPCR was performed on two intertidal surface sediments of the Westerschelde estuary characterized by a two-fold difference in MPB biomass but no difference in MPB composition. Doubling of MPB biomass was accompanied by a disproportionately (ten-fold) increase in total bacterial abundances while, unexpectedly, no difference in general community structure was observed, despite significantly lower bacterial richness and distinct community membership, mostly for non-abundant taxa. Denitrifier abundances corresponded likewise while community structure, both for nirS and nirK denitrifiers, remained unchanged, suggesting that competition with diatoms for nitrate is negligible at concentrations in the investigated sediments (appr. 1 mg/l NO3-). This study indicates that MPB biomass increase has a general, significantly positive effect on total bacterial and denitrifier abundances, with stimulation or inhibition of specific bacterial groups that however do not result in a re-structured community. PMID:25961719

  14. A Doubling of Microphytobenthos Biomass Coincides with a Tenfold Increase in Denitrifier and Total Bacterial Abundances in Intertidal Sediments of a Temperate Estuary

    PubMed Central

    Decleyre, Helen; Heylen, Kim; Sabbe, Koen; Tytgat, Bjorn; Deforce, Dieter; Van Nieuwerburgh, Filip; Van Colen, Carl; Willems, Anne

    2015-01-01

    Surface sediments are important systems for the removal of anthropogenically derived inorganic nitrogen in estuaries. They are often characterized by the presence of a microphytobenthos (MPB) biofilm, which can impact bacterial communities in underlying sediments for example by secretion of extracellular polymeric substances (EPS) and competition for nutrients (including nitrogen). Pyrosequencing and qPCR was performed on two intertidal surface sediments of the Westerschelde estuary characterized by a two-fold difference in MPB biomass but no difference in MPB composition. Doubling of MPB biomass was accompanied by a disproportionately (ten-fold) increase in total bacterial abundances while, unexpectedly, no difference in general community structure was observed, despite significantly lower bacterial richness and distinct community membership, mostly for non-abundant taxa. Denitrifier abundances corresponded likewise while community structure, both for nirS and nirK denitrifiers, remained unchanged, suggesting that competition with diatoms for nitrate is negligible at concentrations in the investigated sediments (appr. 1 mg/l NO3-). This study indicates that MPB biomass increase has a general, significantly positive effect on total bacterial and denitrifier abundances, with stimulation or inhibition of specific bacterial groups that however do not result in a re-structured community. PMID:25961719

  15. Spatiotemporal climatic, hydrological, and environmental variations based on records of annually laminated lake sediments from northern Poland

    NASA Astrophysics Data System (ADS)

    Tylmann, W.; Blanke, L.; Kinder, M.; Loewe, T.; Mayr, C.; Ohlendorf, C.; Zolitschka, B.

    2009-12-01

    In northern Poland there is the unique opportunity to compare varved lake sediment records with distinct climatic trends along a 700 km long W-E transect. Annually laminated Holocene sediment sequences from Lake Lubinskie, Lake Suminko, Lake Lazduny, and Lake Szurpily were cored for high-resolution multiproxy climate and environmental reconstruction in the framework of the Polish-German project “Northern Polish Lake Research” (NORPOLAR). First results from a 139 cm long gravity core of Lake Lazduny (53°51.4’N, 21°57.3’E) document deposition of an organic (mean organic matter: 13.9%; mean biogenic opal: 9.8%) and highly carbonaceous gyttja (mean calcite content: 61.6%). The finely laminated sediment consists of biochemical varves. Pale spring/summer layers composed of autochthonous carbonates alternate with dark fall/winter layers made of organic and minerogenic detritus. The established chronology for the last 1500 calendar-years is based on thin section analysis supported by independent radiometric dating (C-14, Pb-210). Sedimentological, geochemical and stable isotope analyses were carried out with a decadal temporal resolution. Additionally, non-destructive and high-resolution XRF scanning data reveal a rhythmic variation in the Ca content that reflects seasonal calcite deposition. Redox-sensitive elements like Fe, Mn and S are interpreted to be the response to mean winter temperatures: colder winter temperatures ? extended lake ice cover ? intensification of meromixis ? increased Fe/Mn ratio. In turn, these parameters can be linked to NAO (North Atlantic Oscillation) variability, because a negative NAO is related to colder and drier conditions in northeastern Europe. Climate variability is also mirrored by the ?13C record of the endogenic calcite fraction. In mid-latitude lakes calcite precipitation is dominated by productivity-controlled consumption of the dissolved inorganic carbon (DIC) pool. Thus the ?13C record potentially provides a proxy for lacustrine primary production related to seasonal water temperature. As human land use considerably increased and modified the nutrient availability since the 19th century, this relationship is not applicable for the upper part of the record. Main future goals of NORPOLAR will be to (1) establish absolute chronologies for all available records covering the entire Holocene; (2) provide high-resolution data sets of paleoredox conditions, paleoproductivity, lake water balance, lacustrine carbon cycles and soil erosion in the catchment areas; (3) link paleodata with modern instrumental and monitoring data to improve the understanding of signal generation from forcing factors via processes to proxy records; and (4) provide regional data sets of reconstructed and quantified climate parameters to be compared with the output of regional climate models.

  16. Timescales of lateral sediment transport in the Panama Basin as revealed by radiocarbon ages of alkenones, total organic carbon and foraminifera

    Microsoft Academic Search

    Stephanie Kusch; Timothy I. Eglinton; Alan C. Mix; Gesine Mollenhauer

    2010-01-01

    Paired radiocarbon measurements on haptophyte biomarkers (alkenones) and on co-occurring tests of planktic foraminifera (Neogloboquadrina dutertrei and Globogerinoides sacculifer) from late glacial to Holocene sediments at core locations ME0005-24JC, Y69-71P, and MC16 from the south-western and central Panama Basin indicate no significant addition of pre-aged alkenones by lateral advection. The strong temporal correspondence between alkenones, foraminifera and total organic carbon

  17. Fluorine in the rocks and sediments of volcanic areas in central Italy: total content, enrichment and leaching processes and a hypothesis on the vulnerability of the related aquifers.

    PubMed

    De Rita, Donatella; Cremisini, Carlo; Cinnirella, Alessandro; Spaziani, Fabio

    2012-09-01

    Rock, sediment and water samples from areas characterised by hydrothermal alterations in the Sabatini and Vico Volcanic Districts, near Rome and the large city of Viterbo, respectively, were collected and analysed to determine the total fluorine (F) content and to understand the F geochemical background level in the volcanic districts of central Italy. Leaching and alteration processes controlling the high concentration of F in water were also investigated. Fluorine concentrations were directly determined (potentiometrically) by an F selective electrode in water samples, while the procedure for rock samples included preliminary F dissolution through alkaline fusion. F concentrations higher than 800 mg kg(-1) were commonly found in the analysed rocks and sediments; the concentration depended on the lithology and on the distance from the alteration areas. A specific successive sampling campaign was conducted in three areas where the F content in sediments was particularly high; in the same areas, measurements of CO(2) flux were also performed to investigate the possible deep origin of F. To verify the relationships among the high F contents in rocks and sediments, the leaching processes involved and the presence of F in the aquifer, we also collected water samples in the western sector of the Sabatini Volcanic District, where hydrothermal manifestations and mineral springs are common. The data were processed using a GIS system in which the F distribution was combined with morphological and geological observations. The main results of our study are that (1) F concentrations are higher in volcanic and recently formed travertine (especially in hydrothermally altered sediments) than in sedimentary rocks and decrease with distance from hydrothermal alteration areas, (2) F is more easily leached from hydrothermally altered rocks and from travertine and (3) sediments enriched with F may indicate the presence of deep regional fractures that represent direct pathways of hydrothermal fluids from the crust to the surface. PMID:21968879

  18. Measurement of the seasonal and annual variability of total column aerosol in a northeastern U.S. network

    SciTech Connect

    Michalsky, J.J.; Schlemmer, J.A.; Harrison, L.C.; Berkheiser, W.E. III [Univ. of Albany, NY (United States). Atmospheric Sciences Research Center; Larson, N.R.; Laulainen, N.S. [Pacific Northwest Lab., Richland, WA (United States)

    1994-09-01

    A network of multi-filter rotating shadowband radiometers has operated since late 1991 in the northeastern US. The data acquired are simultaneous measurements of total and diffuse horizontal irradiances in six narrowband filtered detectors and one broadband shortwave detector. The direct normal irradiances are calculated from these measurements. These direct data are corrected for cosine response and used to calculate extraterrestrial irradiance (I{sub o}) using the Langley method of regressing the natural logarithm of direct irradiance versus air mass. With frequent determinations of I{sub o}, changes in I{sub o} caused by soiling and filter degradation, for example, can be tracked. Using these I{sub o}`s, total optical depth is calculated for every clear 30-minute period in the record. Consequently, total optical depth may be obtained on a fair number of days throughout the year. Using daily average total optical depth the authors have calculated aerosol optical depths for five wavelengths by subtracting Rayleigh scattering optical depths and Chappuis ozone absorption optical depths at each wavelength. The aerosol pattern at nearly every site is an annual cycle superimposed on a decaying stratospheric loading associated with the Mount Pinatubo volcanic eruption. An attempt is made to remove the volcanic signal using data from another site.

  19. Artificial radionuclides ??Sr and ²?¹Am in the sediments of the Baltic Sea: total and spatial inventories and some temporal trends.

    PubMed

    Hutri, Kaisa-Leena; Mattila, Jukka; Ikäheimonen, Tarja Tuulikki; Vartti, Vesa-Pekka

    2013-05-15

    The Baltic Sea was contaminated by radioactivity following global nuclear fallout and later by the Chernobyl accident. Despite the decrease of radioactivity caused by radioactive decay, radionuclides have a prolonged residence time in the water of the Baltic Sea due to slow water exchange and relatively rapid sedimentation. Very little is known about the amounts or spatial differences of ??Sr and ²?¹Am in the Baltic Sea sediments. In this study, 20 sediment cores taken around the Baltic Sea were investigated to estimate inventories of these radionuclides. The rough results show that the Chernobyl fallout added the amount of ??Sr in the same areas where the increase of ¹³?Cs can be detected, whereas this is not the case for ²?¹Am which is more evenly distributed in the sea bottom. In addition, local differences occur in the concentrations. These results are an important amendment to the radioactivity baseline of the Baltic Sea. PMID:23582977

  20. Dioxin chronology and fluxes in sediments of the Houston Ship Channel, Texas: influences of non-steady-state sediment transport and total organic carbon.

    PubMed

    Yeager, Kevin M; Santschi, Peter H; Rifai, Hanadi S; Suarez, Monica P; Brinkmeyer, Robin; Hung, Chin-Chang; Schindler, Kimberly J; Andres, Michael J; Weaver, Erin A

    2007-08-01

    Polychlorinated dibenzo-p-dioxins and dibenzofurans (dioxins) are persistent contaminants that bioaccumulate and pose serious risks to humans. The primary objective of this study was to determine the history and mechanisms of dioxin accumulation in sediments of the Houston Ship Channel (HSC) using analytical data on natural and anthropogenic radionuclides (7Be, 137Cs, and 210Pb) and dioxins. Results showed that present-day sedimentary dioxin accumulation rates are orders of magnitude higher than atmospheric inputs to the HSC. Most stations showed dioxin peaks in the near surface, indicating continuing inputs despite federal regulations. Stations with high dioxin inventories reflect accentuated accumulation in the HSC as one moves west toward Houston, at the confluence of the HSC and the San Jacinto River and upstream in the San Jacinto River. These results indicate that a significant quantity of dioxins continues to be released into the environment here or that sedimentary storage and release of previously supplied dioxins is significant, or both. The results support the interpretation that the HSC is influenced by episodic sediment resuspension, erosion and lateral transport processes driven by tides, wind, shipping, and dredging, which can cause intermittently high accumulations of dioxins, and underscores the need for additional research on the roles of sedimentary processes in organic contaminant bioavailability. PMID:17822093

  1. Analysis of bottom sediment to estimate nonpoint-source phosphorus loads for 1981-96 in Hillsdale Lake, northeast Kansas

    USGS Publications Warehouse

    Juracek, K.E.

    1997-01-01

    Bottom sediment in Hillsdale Lake, northeast Kansas, was analyzed as a means of estimating the annual load of total phosphorus deposited in the lake from nonpoint sources. Topographic, bathymetric, and sediment-core data were used to estimate the total mass of phosphorus in the lake-bottom sediment. Available streamflow and water-quality data were used to compute the mean annual mass of phosphorus (dissolved plus suspended) exiting the lake as well as the mean annual load of phosphorus added to the lake from point sources. A simple mass balance then was used to compute the mean annual load of phosphorus from nonpoint sources. Mean annual sediment deposition from 1981 through 1996 was estimated to be 265 million pounds (120 million kilograms). The total mass of phosphorus in the lake-bottom sediment was estimated to be 924,000 kilograms, with a mean annual load of 62,000 kilograms. The mean annual mass of phosphorus exiting in the lake out-flow was estimated to be about 8,000 kilograms. The mean annual loads of phosphorus added to the lake from point and nonpoint sources were estimated to be 5,000 and 65,000 kilograms, respectively. Thus, the contribution to the total mean annual phosphorus load in Hillsdale Lake from point sources is about 7 percent and from nonpoint sources, about 93 percent.

  2. Riverine sediment inflow to Louisiana Chenier Plain in the Northern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Rosen, Timothy; Xu, Y. Jun

    2011-12-01

    The Louisiana Chenier Plain is a geomorphologic extension of the Mississippi Deltaic Plain, highly influenced by sediments originating from the Mississippi River. With the Mississippi River unable to avulse closer to the Plain local riverine sediment resources are integral to maintaining the physical and ecological integrity of the estuaries and marshlands. To gain insight into the sediment resources, this study assessed two decades (1990-2009) of discharge and total suspended solids (TSS) of four rivers, Sabine River, Calcasieu River, Mermentau River, and Vermilion River that flow into the Chenier Plain. The study quantified long-term sediment delivery, analyzed seasonal and inter-annual trends of sediment transport, and investigated the effect of hydrometeorological conditions on sediment yields. Total sediment delivery from the rivers over the 20-year period was 6.86 × 10 6 tonnes, with the Sabine River contributing 62% of the sediment load. The Sabine River also showed a significant decreasing trend ( p = 0.03) in annual sediment yield. Long-term trends of sediment loads in all the rivers were influenced by their discharge, not their TSS concentrations. Annual mean sediment load was 342,950 tonnes with higher sediment loading during the winter and spring months and lower during the summer and fall months. Annual sediment inflow has the capacity to create 2.3 × 10 7 m 2 of land to the depth of 1 cm, but most of this sediment is unable to reach the coastline. The greatest asset that these rivers provide for the Chenier Plain is sediment and freshwater for restoration of marsh lost to salinization or inundation.

  3. Wind erosion from a sagebrush steppe burned by wildfire: Measurements of PM10 and total horizontal sediment flux

    NASA Astrophysics Data System (ADS)

    Wagenbrenner, Natalie S.; Germino, Matthew J.; Lamb, Brian K.; Robichaud, Peter R.; Foltz, Randy B.

    2013-09-01

    Wind erosion and aeolian transport processes are under studied compared to rainfall-induced erosion and sediment transport on burned landscapes. Post-fire wind erosion studies have predominantly focused on near-surface sediment transport and associated impacts such as on-site soil loss and site fertility. Downwind impacts, including air quality degradation and deposition of dust or contaminants, are also likely post-fire effects; however, quantitative field measurements of post-fire dust emissions are needed for assessment of these downwind risks. A wind erosion monitoring system was installed immediately following a desert sagebrush and grass wildfire in southeastern Idaho, USA to measure wind erosion from the burned landscape. This paper presents measurements of horizontal sediment flux and PM10 vertical flux from the burned area. We determined threshold wind speeds and corresponding threshold friction velocities to be 6.0 and 0.20 m s-1, respectively, for the 4 months immediately following the fire and 10 and 0.55 m s-1 for the following spring months. Several major wind erosion events were measured in the months following the July 2010 Jefferson Fire. The largest wind erosion event occurred in early September 2010 and produced 1495 kg m-1 of horizontal sediment transport within the first 2 m above the soil surface, had a maximum PM10 vertical flux of 100 mg m-2 s-1, and generated a large dust plume that was visible in satellite imagery. The peak PM10 concentration measured on-site at a height of 2 m in the downwind portion of the burned area was 690 mg m-3. Our results indicate that wildfire can convert a relatively stable landscape into one that is a major dust source.

  4. Analysis of lake-bottom sediment to estimate historical nonpoint-source phosphorus loads

    USGS Publications Warehouse

    Juracek, K.E.

    1998-01-01

    Bottom sediment in Hillsdale Lake, Kansas, was analyzed to estimate the annual load of total phosphorus deposited in the lake from nonpoint sources. Topographic, bathymetric, and sediment-core data were used to estimate the total mass of phosphorus in the lake-bottom sediment. Available streamflow and water-quality data were used to compute the mean annual mass of phosphorus (dissolved plus suspended) exiting the lake. The mean annual load of phosphorus added to the lake from point sources was estimated from previous studies. A simple mass balance then was used to compute the mean annual load of phosphorus from nonpoint sources. The total mass of phosphorus in the lake-bottom sediment was estimated to be 924,000 kg, with a mean annual load of 62,000 kg. The mean annual mass of phosphorus exiting in the lake outflow was estimated to be about 8,000 kg. The mean annual loads of phosphorus added to the lake from point and nonpoint sources were estimated to be 5,000 and 65,000 kg, respectively. Thus, the contribution to the total mean annual phosphorus load in Hillsdale Lake is about 7 percent from point sources and about 93 percent from nonpoint sources.

  5. 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 implies that crayfish can be important drivers of sediment movement in infested rivers. Moreover, observations suggest that a large proportion of the sediment available for transport during winter floods is introduced by bank retreat caused by crayfish burrowing. This implies that the total effect of crayfish on sediment yield is substantially greater than estimates based on entrainment effects alone.

  6. Nutrient, suspended-sediment, and total suspended-solids data for surface water in the Great Salt Lake basins study unit, Utah, Idaho, and Wyoming, 1980-95

    USGS Publications Warehouse

    Hadley, Heidi K.

    2000-01-01

    Selected nitrogen and phosphorus (nutrient), suspended-sediment and total suspended-solids surface-water data were compiled from January 1980 through December 1995 within the Great Salt Lake Basins National Water-Quality Assessment study unit, which extends from southeastern Idaho to west-central Utah and from Great Salt Lake to the Wasatch and western Uinta Mountains. The data were retrieved from the U.S. Geological Survey National Water Information System and the State of Utah, Department of Environmental Quality, Division of Water Quality database. The Division of Water Quality database includes data that are submitted to the U.S. Environmental Protection Agency STOrage and RETrieval system. Water-quality data included in this report were selected for surface-water sites (rivers, streams, and canals) that had three or more nutrient, suspended-sediment, or total suspended-solids analyses. Also, 33 percent or more of the measurements at a site had to include discharge, and, for non-U.S. Geological Survey sites, there had to be 2 or more years of data. Ancillary data for parameters such as water temperature, pH, specific conductance, streamflow (discharge), dissolved oxygen, biochemical oxygen demand, alkalinity, and turbidity also were compiled, as available. The compiled nutrient database contains 13,511 samples from 191 selected sites. The compiled suspended-sediment and total suspended-solids database contains 11,642 samples from 142 selected sites. For the nutrient database, the median (50th percentile) sample period for individual sites is 6 years, and the 75th percentile is 14 years. The median number of samples per site is 52 and the 75th percentile is 110 samples. For the suspended-sediment and total suspended-solids database, the median sample period for individual sites is 9 years, and the 75th percentile is 14 years. The median number of samples per site is 76 and the 75th percentile is 120 samples. The compiled historical data are being used in the basinwide sampling strategy to characterize the broad-scale geographic and seasonal water-quality conditions in relation to major contaminant sources and background conditions. Data for this report are stored on a compact disc.

  7. Compilation of mean annual suspended-sediment yields for selected streams draining basins within and adjacent to coal fields in the eastern United States

    USGS Publications Warehouse

    Hickman, R.E.

    1989-01-01

    Mean annual suspended-sediment yields are listed for 481 selected stations on streams draining basins within and adjacent to the coal fields of the Eastern Coal Province and the eastern region of the Interior Coal Province of the Eastern United States. The drainage basin of each of these stations has an area of 100 and 10,000 sq km; one third or less of the basin drains to a manmade impoundment. Also listed are the percentage of the basin covered by forest, the mean stream-channel gradient of the basin, and any coal-mining activity in the basin. (USGS)

  8. The role of midlatitude mixing barriers in creating the annual variation of total ozone in high northern latitudes

    NASA Astrophysics Data System (ADS)

    Gille, John; Karol, Svetlana; Kinnison, Douglas; Lamarque, Jean-Francois; Yudin, Valery

    2014-08-01

    Data from the HIgh Resolution Dynamics Limb Sounder (HIRDLS), the Microwave Limb Sounder (MLS), and the Whole Atmosphere Community Climate Model (WACCM) are used to investigate the annual variation of total column ozone in high northern latitudes. Downward transport of ozone-rich air by the residual mean circulation during autumn and winter bends ozone isopleths down and increases the high-latitude ozone amounts, leading to an ozone maximum at the end of the winter. During the summer months eddy mixing acts to restore pre-fall distributions of ozone. In this study the large-scale mixing in the lower stratosphere is analyzed using Nakamura's (1996) equivalent length formulation with observed and simulated ozone. The analysis of ozone mixing is performed in the tracer equivalent latitude-potential temperature coordinate system. Steep latitudinal gradients of ozone isopleths below about 500 K occur during the winter, where there are minima in the equivalent length, indicating barriers to mixing at 30°N-40°N. This transport barrier allows large ozone maxima to develop poleward of it. The barrier disappears over the summer, permitting latitudinal mixing of the high ozone air. Above 500 K mixing is more effective during the winter, so a large winter maximum does not occur. In both midlatitude and high latitude the lower stratospheric layer from 330 to 500 K doubles its ozone content from autumn to spring, compared with much smaller changes in the layer from 500 to 650 K. Our results confirm that the presence of the winter transport barrier in the lower stratosphere controls the seasonal variation of total ozone.

  9. Physical and chemical characteristics including total and geochemical forms of phosphorus in sediment from the top 30 centimeters of cores collected in October 2006 at 26 sites in Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Simon, Nancy S.; Ingle, Sarah N.

    2011-01-01

    ?This study of phosphorus (P) cycling in eutrophic Upper Klamath Lake (UKL), Oregon, was conducted by the U.S. Geological Survey in cooperation with the U.S. Bureau of Reclamation. Lakebed sediments from the upper 30 centimeters (cm) of cores collected from 26 sites were characterized. Cores were sampled at 0.5, 1.5, 2.5, 3.5, 4.5, 10, 15, 20, 25, and 30 cm. Prior to freezing, water content and sediment pH were determined. After being freeze-dried, all samples were separated into greater than 63-micron (?m) particle-size (coarse) and less than 63-?m particle-size (fine) fractions. In the surface samples (0.5 to 4.5 cm below the sediment water interface), approximately three-fourths of the particles were larger than 63-?m. The ratios of the coarse particle-size fraction (>63 ?m) and the fine particle-size fraction (<63 ?m) were approximately equal in samples at depths greater than 10 cm below the sediment water interface. Chemical analyses included both size fractions of freeze-dried samples. Chemical analyses included determination of total concentrations of aluminum (Al), calcium (Ca), carbon (C), iron (Fe), poorly crystalline Fe, nitrogen (N), P, and titanium (Ti). Total Fe concentrations were the largest in sediment from the northern portion of UKL, Howard Bay, and the southern portion of the lake. Concentrations of total Al, Ca, and Ti were largest in sediment from the northern, central, and southernmost portions of the lake and in sediment from Howard Bay. Concentrations of total C and N were largest in sediment from the embayments and in sediment from the northern arm and southern portion of the lake in the general region of Buck Island. Concentrations of total C were larger in the greater than 63-?m particle-size fraction than in the less than 63-?m particle-size fraction. Sediments were sequentially extracted to determine concentrations of inorganic forms of P, including loosely sorbed P, P associated with poorly crystalline Fe oxides, and P associated with mineral phases. The difference between the concentration of total P and sum of the concentrations of inorganic forms of P is referred to as residual P. Residual P was the largest fraction of P in all of the sediment samples. In UKL, the correlation between concentrations of total P and total Fe in sediment is poor (R2<0.1). The correlation between the concentrations of total P and P associated with poorly crystalline Fe oxides is good (R2=0.43) in surface sediment (0.5-4.5 cm below the sediment water interface) but poor (R2<0.1) in sediments at depths between 10 cm and 30 cm. Phosphorus associated with poorly crystalline Fe oxides is considered bioavailable because it is released when sediment conditions change from oxidizing to reducing, which causes dissolution of Fe oxides.

  10. Sedimentation, sediment quality, and upstream channel stability, John Redmond Reservoir, east-central Kansas, 1964-2009

    USGS Publications Warehouse

    Juracek, Kyle E.

    2010-01-01

    A combination of available bathymetric-survey information, bottom-sediment coring, and historical streamgage information was used to investigate sedimentation, sediment quality, and upstream channel stability for John Redmond Reservoir, east-central Kansas. Ongoing sedimentation is reducing the ability of the reservoir to serve several purposes including flood control, water supply, and recreation. The total estimated volume and mass of bottom sediment deposited between 1964 and 2009 in the conservation pool of the reservoir was 1.46 billion cubic feet and 55.8 billion pounds, respectively. The estimated sediment volume occupied about 41 percent of the conservation-pool, water-storage capacity of the reservoir. Water-storage capacity in the conservation pool has been lost to sedimentation at a rate of about 1 percent annually. Mean annual net sediment deposition since 1964 in the conservation pool of the reservoir was estimated to be 1.24 billion pounds per year. Mean annual net sediment yield from the reservoir basin was estimated to be 411,000 pounds per square mile per year Information from sediment cores shows that throughout the history of John Redmond Reservoir, total nitrogen concentrations in the deposited sediment generally were uniform indicating consistent nitrogen inputs to the reservoir. Total phosphorus concentrations in the deposited sediment were more variable than total nitrogen indicating the possibility of changing phosphorus inputs to the reservoir. As the principal limiting factor for primary production in most freshwater environments, phosphorus is of particular importance because increased inputs can contribute to accelerated reservoir eutrophication and the production of algal toxins and taste-and-odor compounds. The mean annual net loads of total nitrogen and total phosphorus deposited in the bottom sediment of the reservoir were estimated to be 2,350,000 pounds per year and 1,030,000 pounds per year, respectively. The estimated mean annual net yields of total nitrogen and total phosphorus from the reservoir basin were 779 pounds per square mile per year and 342 pounds per square mile per year, respectively. Trace element concentrations in the bottom sediment of John Redmond Reservoir generally were uniform over time. As is typical for eastern Kansas reservoirs, arsenic, chromium, and nickel concentrations typically exceeded the threshold-effects guidelines, which represent the concentrations above which toxic biological effects occasionally occur. Trace element concentrations did not exceed the probable-effects guidelines (available for eight trace elements), which represent the concentrations above which toxic biological effects usually or frequently occur. Organochlorine compounds either were not detected or were detected at concentrations that were less than the threshold-effects guidelines. Stream channel banks, compared to channel beds, likely are a more important source of sediment to John Redmond Reservoir from the upstream basin. Other sediment sources include surface-soil erosion in the basin and shoreline erosion in the reservoir.

  11. Diatoms (Class Bacillariophyceae) and geochemistry from annually laminated mid-Holocene sediments, west coast Canada: insights into abrupt climate change in the past

    NASA Astrophysics Data System (ADS)

    Chang, A.; Pedersen, T. F.

    2009-04-01

    A 115-year record of annually laminated sediments from Effingham Inlet, a small anoxic fjord on the west coast of Vancouver Island, British Columbia (49?N, 125?W), was analyzed for diatoms (species and abundances) and geochemistry (C and N isotopes, organic C and trace elements Ag, Cd, Re and Mo) from a piston core. The sediments were radiocarbon dated at approx. 4200-4400 years before present (yr BP) and show diatom enriched varves in the lower 70 years, with a sudden transition to diatom impoverished varves above. In the lower section, varves are thick (2-5 mm) and consist of well-defined Thalassiosira-Skeletonema-Chaetoceros spring bloom successions. Diatom concentrations average at 787 ± 733 million valves/g of dry sediment, del 15N at 7.0 ± 0.5 per mil, and organic C at 5.2 ± 0.5 wt. %. In the upper section, the varves are thinner (1-2 mm), do not clearly show the seasonal diatom succession, and contain increased terrigenous detritus. Diatom concentrations average at 388 ± 202 million valves/g with an increased relative abundance of benthic and freshwater taxa, del 15N at 7.3 ± 0.6 per mil and organic C at 5.7 ± 0.5 wt. %. Values of del 13C for both sections are similar, averaging at -24.0 ± 0.5 per mil. The trace element concentrations are quite variable throughout the section. However, several thin (<1 cm) nonlaminated intervals show decreased diatom abundances with concomitant increases in trace element concentrations, suggesting short-lived changes in surface productivity, upwelling and nutrient delivery, and/or anoxic conditions. The abrupt transition from diatom-rich to diatom-poor varves could reflect a shift in dominance of the North Pacific High and Aleutian Low atmospheric pressure systems over the northeast Pacific Ocean, not unlike the well-documented 1976/1977 climate regime shift which showed a change in upwelling and nutrient delivery. A transition between warm and sunny climates to cooler and wetter regimes at around 4000 yr BP has been noted in previous paleoenvironmental studies from British Columbia and the northern hemisphere in general. The Effingham Inlet sediment record data will also be compared with modern sediment trap data from the inlet.

  12. Evaluation of spatial and temporal variations in marine sediments quality using multivariate statistical techniques.

    PubMed

    Alvarez, Odalys Quevedo; Tagle, Margarita Edelia Villanueva; Pascual, Jorge L Gómez; Marín, Ma Teresa Larrea; Clemente, Ana Catalina Nuñez; Medina, Miriam Odette Cora; Palau, Raiza Rey; Alfonso, Mario Simeón Pomares

    2014-10-01

    Spatial and temporal variations of sediment quality in Matanzas Bay (Cuba) were studied by determining a total of 12 variables (Zn, Cu, Pb, As, Ni, Co, Al, Fe, Mn, V, CO?²?, and total hydrocarbons (THC). Surface sediments were collected, annually, at eight stations during 2005-2008. Multivariate statistical techniques, such as principal component (PCA), cluster (CA), and lineal discriminant (LDA) analyses were applied for identification of the most significant variables influencing the environmental quality of sediments. Heavy metals (Zn, Cu, Pb, V, and As) and THC were the most significant species contributing to sediment quality variations during the sampling period. Concentrations of V and As were determined in sediments of this ecosystem for the first time. The variation of sediment environmental quality with the sampling period and the differentiation of samples in three groups along the bay were obtained. The usefulness of the multivariate statistical techniques employed for the environmental interpretation of a limited dataset was confirmed. PMID:25015344

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

    USGS Publications Warehouse

    Von Guerard, Paul

    1989-01-01

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

  14. Millenial long near-annual summer temperature reconstruction from abiotic sediment characterstics of varved Lake Silvaplana (eastern Swiss Alps)

    Microsoft Academic Search

    M. Trachsel; C. Kamenik; M. Grosjean; I. Larocque; A. Blass; M. Sturm

    2009-01-01

    In this study we present a summer temperature reconstruction based on multiple geochemical and sedimentological climate proxies from annually laminated Lake Silvaplana (eastern Swiss Alps), covering the last millennium. These proxies, including mass accumulation rate, biogenic silica flux, XRD peak intensity ratios and in situ reflectance spectroscopy reflect summer temperature. Individually they show excellent calibration statistics on subdecadal time scales

  15. ANNUAL PROGRESS REPORT. SPECTROSCOPIC AND MICROSCOPIC CHARACTERIZATION OF CONTAMINANT UPTAKE AND RETENTION BY CARBONATES IN SOILS AND VADOSE ZONE SEDIMENTS

    EPA Science Inventory

    This report summarizes work completed after 21 months of a 36-month project. In a previous annual report we described results of contaminant uptake by natural caliche from the Pasco Basin area. The new results described here relate to studies of metal coprecipitation with calcite...

  16. Erosion, sediment discharge, and channel morphology in the Upper Chattahoochee River basin, Georgia

    USGS Publications Warehouse

    Faye, Robert E.; Carey, W.R.; Stamer, J.K.; Kleckner, R.L.

    1978-01-01

    Average annual rates of sheet erosion and sediment discharge were computed for several watersheds in the Upper Chattahoochee River basin in Georgia. Erosion yields ranged from about 900 to 6,000 tons per year per square mile in nine watersheds and were greatest where land use is largely agricultural or transitional. Suspended sediment yields from the same watershed ranged from about 300 to 800 tons per year per square mile and were greatest from urban areas and least from mostly forested watersheds. The impact of suspended sediment on stream quality was evaluated for 14 watersheds. In general, 60 percent or more of the total annual discharge of trace metals and phosphorus was contributed by suspended sediment. Yields of trace metals and nutrients in suspension were consistently greater in urban watersheds. Turbidity in basin streams increased geometrically with increasing concentrations of suspended sediment. (Woodard-USGS)

  17. A ca. 800Year Lithologic Record of Drought from Sub-annually Laminated Lake Sediment, East Java

    Microsoft Academic Search

    Shelley D. Crausbay; James M. Russell; Douglas W. Schnurrenberger

    2006-01-01

    Lithostratigraphic analyses of a sub-annually laminated core from Ranu Lamongan, a maar lake on the island of Java, document\\u000a considerable changes in the lake’s chemistry and water balance over the past ca. 800 calendar years. Composition of the dark\\u000a (clastics) and light (diatoms and\\/or calcium carbonate minerals) couplets suggests that these laminations form in response\\u000a to seasonal changes in rainfall

  18. SEDIMENTATION PATTERNS AND DEPOSITION IN THE PROGRADING WAX LAKE DELTA

    NASA Astrophysics Data System (ADS)

    Bailey, C. H.; Holm, G. O.

    2009-12-01

    The Mississippi River has been dammed and levied since the 1950s to control the river from flooding and support navigation and commerce. Sediments delivered to the Louisiana delta plain have decreased by half since the major projects of the 1950’s. Despite significant reductions in sediment load, the Wax Lake Delta is forming at the mouth of a man made dredged channel that flows off of the Atchafalaya River, which is the principal distributary of the Mississippi River. The remaining sediments carried by the Mississippi River are essential in the building of delta wetlands and helping to reverse coastal wetland loss. This study analyzes pre- and post-elevation data from 2008 and 2009 to understand the amount of elevation gain and sediment deposition associated with large river floods. Mean wetland elevation gain during the floods of 2008 and 2009 was 3.9 cm and 2.2 cm, respectively. Using soil bulk properties and mean elevation gain, I estimated that 2.3x106 Mt and 1.2x106Mt of sediment was deposited in the Wax Lake Delta wetlands for 2008 and 2009, respectively. If the total annual load of sediments in the Atchafalaya River is approximately 50Mt yr-1, we can estimate that <10% of the total available sediment load is deposited in the wetlands, just during spring flood events. This study provides good first order estimates of sediment deposition that can contribute to future research and understanding of the Wax Lake Delta formation and maintenance.

  19. Effects of Alder Mine on the Water, Sediments, and Benthic Macroinvertebrates of Alder Creek, 1998 Annual Report.

    SciTech Connect

    Peplow, Dan

    1999-05-28

    The Alder Mine, an abandoned gold, silver, copper, and zinc mine in Okanogan County, Washington, produces heavy metal-laden effluent that affects the quality of water in a tributary of the Methow River. The annual mass loading of heavy metals from two audits at the Alder Mine was estimated to exceed 11,000 kg per year. In this study, water samples from stations along Alder Creek were assayed for heavy metals by ICP-AES and were found to exceed Washington State's acute freshwater criteria for cadmium (Cd), copper (Cu), selenium (Se), and zinc (Zn).

  20. Development and evaluation of a new catchment-scale model of floodplain sedimentation

    NASA Astrophysics Data System (ADS)

    Nicholas, A. P.; Walling, D. E.; Sweet, R. J.; Fang, X.

    2006-10-01

    Fine-sediment storage within floodplain systems typically represents a significant component of the catchment sediment budget and a primary control on sediment-associated nutrient and contaminant fluxes at the basin scale. However, quantitative modeling of floodplain sedimentation within whole catchments represents a significant challenge, not least because hydraulic controls on sediment transport and deposition processes operate at fine spatial scales that cannot be resolved by basin-scale models. This paper outlines a new approach to addressing this problem in order to develop a computationally efficient model of floodplain sedimentation, which retains a strong physical basis. The approach involves two stages. First, a simple theoretical model of overbank sedimentation is presented, which quantifies the relationship between floodplain geometry, overbank discharge, and total sedimentation rate. Second, the precise form that such a relationship should take is established by analysis of the output from high-resolution flow and suspended sediment transport models applied to 22 floodplain reaches along three U.K. rivers. This analysis supports a simple power law model between discharge in excess of bankfull and sedimentation rate per unit valley floor length per unit sediment concentration. The power law model is then incorporated within a sediment budget framework and implemented using a Monte Carlo approach to allow an assessment of uncertainty in the model parameterization. The relative likelihood of competing model structures is determined using estimates of mean annual floodplain sediment storage derived by analysis of the 137Cs content of floodplain sediment cores. Comparison of 137Cs-derived sedimentation rates with uncertainty-bounded model predictions highlights the potential for assessing the significance of overbank sedimentation within catchment sediment budgets using the simple power law model.

  1. Comparative Aspects of Sulfur Mineralization in Sediments of a Eutrophic Lake Basin †

    PubMed Central

    King, Gary M.; Klug, M. J.

    1982-01-01

    The net mineralization of organic sulfur compounds in surface sediments of Wintergreen Lake was estimated from a mass-balance budget of sulfur inputs and sediment sulfur concentrations. The net mineralization of organic sulfur inputs is <50% complete, which is consistent with the dominance of organic sulfur (>80% of total sulfur) in sediment. Although sediment sulfur is predominantly organic, sulfate reduction is the most significant process in terms of the quantities of sulfur transformed in surface sediments. Rates of sulfate reduction in these sediments average 7 mmol/m2 per day. On an annual basis, this rate is 19-fold greater than net rates of organic sulfur mineralization and 65-fold greater than sulfate ester hydrolysis. PMID:16346037

  2. Long-term runoff and sediment yields from small semiarid watersheds in southern Arizona

    Microsoft Academic Search

    V. O. Polyakov; M. A. Nearing; M. H. Nichols; R. L. Scott; J. J. Stone; M. P. McClaran

    2010-01-01

    This study presents analysis of 34 years of precipitation, runoff, and sediment data collected from eight small (1.1–4.0 ha) semiarid rangeland watersheds in southern Arizona, USA. Average annual precipitation ranged between 354 and 458 mm with 53% of the total rainfall occurring from July through September. Runoff depth was 3.5%–13.9% of annual precipitation depth for individual watersheds and 9.2% on

  3. Sediment yield estimation in a small watershed on the northern Loess Plateau, China

    NASA Astrophysics Data System (ADS)

    Zhao, Guangju; Klik, Andreas; Mu, Xingmin; Wang, Fei; Gao, Peng; Sun, Wenyi

    2015-07-01

    Soil erosion is a major form of land degradation throughout the world and the key environmental problem that threatens the ecosystem of the Chinese Loess Plateau. In this study, we determined the sediment yield from a small dam-controlled watershed in the Huangfuchuan watershed, northern Loess Plateau, with a drainage area of 0.64 km2. The dam infill sediment provided evidence of at least 31 flood couplets, which corresponded to rain storms during 1958-1972. In total, 1.65 × 105 t sediment was accumulated within the whole check dams in this period. The annual sediment yield ranged from null in 1965 to 59,990 t in 1959. We used the modified WATEM/SEDEM model to simulate soil erosion and the sediment yield in the watershed and the sedimentation records were used for model verification. The model produced satisfactory results; the total soil erosion and sediment delivery ratio were estimated to be 1.97 × 105 t and 83.6%, respectively. Bare weathered stone in the steep gullies contributed > 90% of the sediment yield, while the remainder was derived mainly from bare loess slopes and the alluvial plain. This study suggests that analyzing sedimentation behind check dams and applying the WATEM/SEDEM model are useful for the quantitative analysis of sediment dynamics in ungauged basins on the Loess Plateau.

  4. SEPAL - a simple GIS-based tool to estimate sediment pathways in lowland catchments

    NASA Astrophysics Data System (ADS)

    Kiesel, J.; Schmalz, B.; Fohrer, N.

    2009-08-01

    Even though soil loss in the lowlands imposes not as much a restriction on land use and agricultural productivity as in erosion affected mountainous areas, the input of fine sediment into the rivers and streams is a concern due to water quality issues and substrate siltation. Drains, river banks and agricultural fields are the three main sources of fine sediment in lowland regions. For a successful implementation of measures to decrease sediment input a well-founded knowledge of the individual entry pathways is essential. To assess the importance of possible entry pathways, a GIS based methodology (SEPAL) has been established combining the ABAG, a river bank erosion formula and a regression approach to include the contributions of drains. SEPAL has been applied on a study catchment in Northern Germany. The results show that 15% of the sediment input into the river comes from agricultural drains, 71% from river banks and 14% from adjacent fields. A comparison of the results with field-mapping and -sampling shows that the approach is plausible. The calculated total annual sediment input is 616 t yr-1, while the measured suspended sediment load is 636 t yr-1. It can be concluded that the methodology is suitable for estimating sediment entry pathways and annual sediment loads in lowland catchments as a base for modelling projects and further investigations. However, further work is necessary for gaining sound knowledge about uncertainties and especially about the processes forcing sediment input from drains.

  5. Assessment of terrigenous organic carbon input to the total organic carbon in sediments from Scottish transitional waters (sea lochs): methodology and preliminary results

    Microsoft Academic Search

    P. S. Loh; A. D. Reeves; J. Overnell; S. M. Harvey; A. E. J. Miller

    2002-01-01

    This paper addresses the assessment of terrestrially derived organic carbon in sediments from two Scottish sea lochs. The results illustrate a smooth decrease in area-specific sediment oxygen uptake rates along a transect of six stations from the head of Loch Creran to the sea, from 18.7 mmol O2 m-2 d-1 to 6.6 mmol O2 m-2 d-1. Measurement of the losses

  6. Enforcing Academic Rules in Higher Education--A Total Quality Management Approach. AIR 1993 Annual Forum Paper.

    ERIC Educational Resources Information Center

    Burgar, Paul

    A case study was done of how Total Quality Management (TQM) was used in a Masters in Business Administration program to prevent rule infractions rather than to punish students. The program allowed students to take up to 20 hours of classes under an unclassified status before they took an admissions test. In order to continue, however, students…

  7. Total Quality Management: Statistics and Graphics III - Experimental Design and Taguchi Methods. AIR 1993 Annual Forum Paper.

    ERIC Educational Resources Information Center

    Schwabe, Robert A.

    Interest in Total Quality Management (TQM) at institutions of higher education has been stressed in recent years as an important area of activity for institutional researchers. Two previous AIR Forum papers have presented some of the statistical and graphical methods used for TQM. This paper, the third in the series, first discusses some of the…

  8. Total and size-fractionated mass of road-deposited sediment in the city of Prince George, British Columbia, Canada: implications for air and water quality in an urban environment

    Microsoft Academic Search

    Philip N. Owens; Katrina A. Caley; Sarah Campbell; Alexander J. Koiter; Ian G. Droppo; Kevin G. Taylor

    Purpose  The urban sedimentary system is attracting increasing interest because of its role in influencing air and water quality. A\\u000a large amount of road-deposited sediment (RDS) lies on the road network of Prince George, a city of about 80,000 people, in\\u000a British Columbia, Canada. The objectives of this study were: (1) to determine the total mass of RDS within the city,

  9. Depositional fluxes of metals and phytoplankton in Windermere as measured by sediment traps

    SciTech Connect

    Hamilton-Taylor, J.; Willis, M.; Reynolds, C.S.

    1984-07-01

    Monthly sediment trap samples collected from a deep water station (42 m) in Windermere for a period of 1 year were analyzed for 0.5 M HCl extractable and total Fe, Mn, Al, Pb, Cu, Zn, total C, N, and total solids. Concomitant algal counts showed the year to be fairly typical in terms of the known sequence of phytoplankton. The annual depositional fluxes are compared with previously determined values based on sediment studies. The ratio of the annual trap to sediment flux for Al indicates the absence of local sediment resuspension. The ratios for Fe, Pb, and Zn suggest some possible biogeochemical cycling at the sediment-water interface. The deposition of Fe, Al, and Pb is predominantly associated with detrital material and occurs mainly during winter. The behavior of Zn is largely independent of other variables examined. The ratios for C, total solids, and Cu are all significantly >1. The major influence on the deposition and recycling of Mn is its well-known redox cycle involving oxidative precipitation and reductive remobilization. Cu undergoes an independent deposition-remobilization cycle, probably related to uptake by diatoms and their rapid microbial decomposition after sedimentation.

  10. Temporal, spatial and size variation in the sediment transport in the Krishna River basin, India

    NASA Astrophysics Data System (ADS)

    Ramesh, R.; Subramanian, V.

    1988-03-01

    The total sediment transport of the Krishna River to the Bay of Bengal is estimated to be 4.11 × 10 6 ton yr -1. The sediment load decreases sharply from 67.72 × 10 6 ton yr -1 from the upstream region ((Morvakonda) to 4.11 × 10 6 ton yr -1 at the river mouth (Vijayawada). The depletion of sediment supply in the river mouth and lack of uniformity in sediment transport within the basin is mainly due to several human activities such as dams, cropping, etc. This has been substantiated by the temporal and spatial variation of the suspended sediments based on fourteen years data (1971-1984). One of the tributaries of the Krishna, the Bhima River is the main sediment contributor to the Krishna with an average annual sediment transport of 25.91 × 10 6 ton and sediment concentration of 2070 mg 1 -1. The bulk of sediment transport (> 95%) takes place in the monsoon period. Erosion rate shows no systematic relationship either spatially or temporarily. The total sediment erosion of the Krishna is estimated to be 16 ton km -2 yr -1. Rates of erosion calculated for various subbasins indicate that smaller basins erode more rapidly than larger basins. The particle size distribution of the suspended sediments were correlated with the mean monthly sediment transportation to evaluate the downstream and temporal variation of grain size with sediment transport. At the river mouth, it is seen that enormous amounts of fine particles (1-10 ?m) add to the monthly sediment load of the river.

  11. The role of two sediment-dwelling invertebrates on the mercury transfer from sediments to the estuarine trophic web

    NASA Astrophysics Data System (ADS)

    Coelho, J. P.; Nunes, M.; Dolbeth, M.; Pereira, M. E.; Duarte, A. C.; Pardal, M. A.

    2008-07-01

    The annual total and organic mercury bioaccumulation pattern of Scrobicularia plana and Hediste diversicolor was assessed to evaluate the potential mercury transfer from contaminated sediments to estuarine food webs. S. plana was found to accumulate more total and organic mercury than H. diversicolor, up to 0.79 mg kg -1 and 0.15 mg kg -1 (wet weight) respectively, with a maximum annual uptake of 0.21 mg kg -1 y -1, while for methylmercury the annual accumulation was similar between species and never exceeded 0.045 mg kg -1 y -1. The higher organic mercury fraction in H. diversicolor is related to the omnivorous diet of this species. Both species increase methylmercury exposure by burrowing activities and uptake in anoxic, methylmercury rich sediment layers. Integration with the annual biological production of each species revealed mercury incorporation rates that reached 28 ?g m -2 y -1, and to extract as much as 11.5 g Hg y -1 (of which 95% associated with S. plana) in the 0.4 km 2 of the most contaminated area, that can be transferred to higher trophic levels. S. plana is therefore an essential vector in the mercury biomagnification processes, through uptake from contaminated sediments and, by predation, to transfer it to economically important and exploited estuarine species.

  12. SEDIMENT REMOVAL

    EPA Science Inventory

    When properly conducted, sediment removal is an effective lake management technique. This chapter describes: (1) purposes of sediment removal, (2) environmental concerns, (3) appropriate depth of sediment removal, (4) sediment removal techniques, (5) suitable lake conditions, (6)...

  13. Sediment removal by prairie filter strips in row-cropped ephemeral watersheds.

    PubMed

    Helmers, Matthew J; Zhou, Xiaobo; Asbjornsen, Heidi; Kolka, Randy; Tomer, Mark D; Cruse, Richard M

    2012-01-01

    Twelve small watersheds in central Iowa were used to evaluate the effectiveness of prairie filter strips (PFS) in trapping sediment from agricultural runoff. Four treatments with PFS of different size and location (100% rowcrop, 10% PFS of total watershed area at footslope, 10% PFS at footslope and in contour strips, 20% PFS at footslope and in contour strips) arranged in a balanced incomplete block design were seeded in July 2007. All watersheds were in bromegrass ( L.) for at least 10 yr before treatment establishment. Cropped areas were managed under a no-till, 2-yr corn ( L.)-soybean [ (L.) Merr.] rotation beginning in 2007. About 38 to 85% of the total sediment export from cropland occurred during the early growth stage of rowcrop due to wet field conditions and poor ground cover. The greatest sediment load was observed in 2008 due to the initial soil disturbance and gradually decreased thereafter. The mean annual sediment yield through 2010 was 0.36 and 8.30 Mg ha for the watersheds with and without PFS, respectively, a 96% sediment trapping efficiency for the 4-yr study period. The amount and distribution of PFS had no significant impact on runoff and sediment yield, probably due to the relatively large width (37-78 m) of footslope PFS. The findings suggest that incorporation of PFS at the footslope position of annual rowcrop systems provides an effective approach to reducing sediment loss in runoff from agricultural watersheds under a no-till system. PMID:23099945

  14. Linking Sediment Characteristics to Methane Emission Potential in Subarctic Lakes

    NASA Astrophysics Data System (ADS)

    Logozzo, L. A.; Perry, A. L.; Wik, M.; Thornton, B. F.; Crill, P. M.; Johnson, J. E.; Varner, R. K.

    2014-12-01

    High latitudes are experiencing warmer average annual temperatures, resulting in the thawing of permafrost, and possibly, the increased emission of methane (CH4) from lakes and ponds. One potential impact of permafrost thaw is increased runoff of organic matter into streams, lakes and ponds. Warming can also potentially increase lake sediment temperatures, resulting in a lower methane (CH4) storage capacity and increased CH4 production. We focused our study on six lakes of varying size, location, and characteristics, located in the Stordalen Mire area in northernmost Sweden. We collected sediment cores in each lake and analyzed the dissolved CH4 in the sediment at various depths in the core. The sediment CH4 concentrations were compared to the grain sizes and compositions (total organic carbon (TOC), total sulfur (S), and total nitrogen) of the sediment at the corresponding depths. We also measured dissolved CH4 concentrations in the lake water and compared them to those of the sediment. We found that on average, the CH4 concentration was higher (16.7 ?gCH4 gds-1 ± 16.4) in sediments with more TOC (31.4 wt % ± 10.8). There was also a strong positive correlation between sediment CH4 and total S (r2 = 0.37, p = 0.165), between sediment CH4 and TOC (r2 = 0.53, p = 0.101), and between TOC and total S (r2 = 0.64, p = 0.066). This indicates in situ production of CH4­ in the lake sediment at depths of peak CH4 concentrations in at least two of the lakes. The peak of dissolved CH4 was located deeper in the cores although this depth varied among the lakes. In four lakes, we found high CH4 concentrations in the sediment, as well as high CH4 concentrations in the water, indicating little oxidation in the water column or persistent CH4 production in the sediment. This suggests that at least four of our studied lakes have great potential to release a substantial amount of their produced CH4 to the atmosphere.

  15. Simultaneously Extracted Metals/Acid-Volatile Sulfide and Total Metals in Surface Sediment from the Hanford Reach of the Columbia RIver and the Lower Snake River

    SciTech Connect

    Patton, Gregory W.; Crecelius, Eric A.

    2001-01-24

    Metals have been identified as contaminants of concern for the Hanford Reach because of upriver mining, industrial activities, and past nuclear material production at the US Department of Energy's Hanford Site. This study was undertaken to better understand the occurrence and fate of metals in sediment disposition areas in the Columbia and Snake Rivers.

  16. Sediment and Fecal Indicator Bacterial Loading in a Mixed Land Use Watershed: Contributions from Suspended and Bed Load Transport

    NASA Astrophysics Data System (ADS)

    Bradshaw, J. K.; Molina, M.; Sullivan, K.; Sidle, R. C.

    2014-12-01

    Water quality studies that quantify sediment and fecal bacteria loading commonly focus on suspended contaminants transported during high flows. Fecal contaminants in bed sediments are typically ignored and need to be considered because of their potential to increase pathogen loadings during high flows that produce bed load transport. Water (containing suspended sediment) and bed load samples (n = 145 & n = 28, respectively) were collected in a 122 km2 watershed located in N.E. Georgia, USA during the 2013 water year. Continuous discharge was calculated from level data using USGS rating curves. This study quantifies total sediment and fecal indicator bacteria loads (FIB) in an alluvial stream in a mixed land use watershed and provides valuable data for parameterization of watershed models that simulate sediment and bacteria transport. Annual loads for sediment and FIB were determined using linear relationships between the following: turbidity and total suspended solids (R2 = 0.96); turbidity and suspended Escherichia coli and enterococci (R2 = 0.54 and 0.67, respectively); discharge and bed load (R2 = 0.60), and discharge and sediment associated E. coli and enterococci (R2 = 0.55 and 0.50, respectively). The annual sediment load was 3660 t with approximately 95% attributed to suspended sediment load and 5% attributed to bed load. The annual E. coli load was 3.7 x 1014 colonies with approximately 99.5% attributed to suspended transport and 0.50% attributed to bed load sediment-associated transport. The annual enterococci load was 1.1 x 1015 colonies with approximately 100% attributed to suspended transport. Bed load sediment transport ranged from 2% to 8% of the total storm sediment load in several high flow events (Q = 5 to 40 m3 s-1). Bed sediment-associated E. coli load was 0.4% to 0.5% of the total storm E. coli load. Suspended transport is the predominant mechanism describing contaminant loading in this stream and load estimates can be determined using simple relationships between discharge and suspended concentrations.

  17. Use of sediment rating curves and optical backscatter data to characterize sediment transport in the Upper Yuba River watershed, California, 2001-03

    USGS Publications Warehouse

    Curtis, Jennifer A.; Flint, Lorraine E.; Alpers, Charles N.; Wright, Scott A.; Snyder, Noah P.

    2006-01-01

    Sediment transport in the upper Yuba River watershed, California, was evaluated from October 2001 through September 2003. This report presents results of a three-year study by the U.S. Geological Survey, in cooperation with the California Ecosystem Restoration Program of the California Bay-Delta Authority and the California Resources Agency. Streamflow and suspended-sediment concentration (SSC) samples were collected at four gaging stations; however, this report focuses on sediment transport at the Middle Yuba River (11410000) and the South Yuba River (11417500) gaging stations. Seasonal suspended-sediment rating curves were developed using a group-average method and non-linear least-squares regression. Bed-load transport relations were used to develop bed-load rating curves, and bed-load measurements were collected to assess the accuracy of these curves. Annual suspended-sediment loads estimated using seasonal SSC rating curves were compared with previously published annual loads estimated using the Graphical Constituent Loading Analysis System (GCLAS). The percent difference ranged from -85 percent to +54 percent and averaged -7.5 percent. During water year 2003 optical backscatter sensors (OBS) were installed to assess event-based suspended-sediment transport. Event-based suspended-sediment loads calculated using seasonal SSC rating curves were compared with loads calculated using calibrated OBS output. The percent difference ranged from +50 percent to -369 percent and averaged -79 percent. The estimated average annual sediment yield at the Middle Yuba River (11410000) gage (5 tons/mi2) was significantly lower than that estimated at the South Yuba River (11417500) gage (14 tons/mi2). In both rivers, bed load represented 1 percent or less of the total annual load throughout the project period. Suspended sediment at the Middle Yuba River (11410000) and South Yuba River (11417500) gages was typically greater than 85 percent silt and clay during water year 2003, and sand concentrations at the South Yuba River (11417500) gage were typically higher than those at the Middle Yuba River (11410000) gage for a given streamflow throughout the three year project period. Factors contributing to differences in sediment loads and grain-size distributions at the Middle Yuba River (11410000) and South Yuba River (11417500) gages include contributing drainage area, flow diversions, and deposition of bed-material-sized sediment in reservoirs upstream of the Middle Yuba River (11410000) gage. Owing to its larger drainage area, higher flows, and absence of man-made structures that restrict sediment movement in the lower basin, the South Yuba River transports a greater and coarser sediment load.

  18. Role of sediment resuspension in the remobilization of particulate-phase metals from coastal sediments

    USGS Publications Warehouse

    Kalnejais, Linda H.; Martin, William R.; Signell, Richard P.; Bothner, Michael H.

    2007-01-01

    The release of particulate-phase trace metals due to sediment resuspension has been investigated by combining erosion chamber experiments that apply a range of shear stresses typically encountered in coastal environments with a shear stress record simulated by a hydrodynamic model. Two sites with contrasting sediment chemistry were investigated. Sediment particles enriched in silver, copper, and lead, 4?50 times greater than the bulk surface-sediment content, were the first particles to be eroded. As the shear-stress level was increased in the chamber, the total mass eroded increased, but the enrichment of these trace metals fell, approaching the bulk-sediment content. From the temporal distribution of shear stress generated by the hydrodynamic model for a site in Boston Harbor, resuspension fluxes were estimated. The erosion threshold of this site is exceeded during spring tides, releasing the particles enriched in trace metals into the water column. Due to the higher trace metal content and the regularity of resuspension, low-energy resuspension events (up to a shear stress of 0.2 N/m2) contribute up to 60% of the resuspension metal flux in an average year. The estimated annual quantity of copper and lead resuspended into the water column is higher than estimates of the total riverine flux for these metals. These results indicate that sediment resuspension is a very important mechanism for releasing metals into the water column and provide new insight into the chemical and physical processes controlling the long-term fate of trace metals in contaminated sediments.

  19. Total Mercury, Methylmercury, Methylmercury Production Potential, and Ancillary Streambed-Sediment and Pore-Water Data for Selected Streams in Oregon, Wisconsin, and Florida, 2003-04

    USGS Publications Warehouse

    Marvin-DiPasquale, Mark C.; Lutz, Michelle A.; Krabbenhoft, David P.; Aiken, George R.; Orem, William H.; Hall, Britt D.; DeWild, John F.; Brigham, Mark E.

    2008-01-01

    Mercury contamination of aquatic ecosystems is an issue of national concern, affecting both wildlife and human health. Detailed information on mercury cycling and food-web bioaccumulation in stream settings and the factors that control these processes is currently limited. In response, the U.S. Geological Survey (USGS) National Water-Quality Assessment Program (NAWQA) conducted detailed studies from 2002 to 2006 on various media to enhance process-level understanding of mercury contamination, biogeochemical cycling, and trophic transfer. Eight streams were sampled for this study: two streams in Oregon, and three streams each in Wisconsin and Florida. Streambed-sediment and pore-water samples were collected between February 2003 and September 2004. This report summarizes the suite of geochemical and microbial constituents measured, the analytical methods used, and provides the raw data in electronic form for both bed-sediment and pore-water media associated with this study.

  20. Importance of Dissolved Neutral Hg-Sulfides, Energy Rich Organic Matter and total Hg Concentrations for Methyl Mercury Production in Sediments

    Microsoft Academic Search

    A. Drott; U. Skyllberg

    2007-01-01

    Methyl mercury (MeHg) is the mercury form that biomagnifies to the greatest extent in aquatic food webs. Therefore information about factors determining MeHg concentrations is critical for accurate risk assessment of contaminated environments. The concentration of MeHg in wetlands and sediments is the net result of: 1) methylation rates, 2) demethylation rates, and 3) input\\/output processes. In this study, the

  1. Streambank-Derived Sediment Delivery to the Great Barrier Reef from the Burnett River over Multiple Time Scales: Implications for Sediment Management

    NASA Astrophysics Data System (ADS)

    Simon, A.; Bankhead, N.; Wilson, P.

    2014-12-01

    Degradation of the Great Barrier Reef (GBR) is in part, the result of the delivery of fine-grained, terrestrial sediment from catchments draining to the Coral Sea. The Burnett River, draining the GBR experienced severe flooding in 2011 and 2013 with the latter flood breaking all historical records. Huge quantities of sediment were transported to the Coral Sea. The purpose of this study was to quantify the magnitude of sediment eroded from the channel banks during the floods, long term bank-erosion rates, and cost-effective protection measures. System-wide analysis combined with numerical modeling using the Bank-Stability and Toe-Erosion Model (BSTEM) was used to determine annual bank-erosion rates over periods ranging from 4.5 to 100 years. Analysis of 2009 and 2013 aerial imagery revealed that 47.3 Mt (10.4 MT/y) of sediment was eroded from the banks of the lower 300 km of the Burnett River. Erosion of these bank materials does not equate to an equal volume exported to the Coral Sea, as an unknown proportion is deposited. It can be assumed, however, that the majority of the fine-grained materials (54%) were transported out to sea. Long-term simulations (42 years) were conducted using BSTEM, to compare longer term averages with those determined by the catchment model SedNet. Over this longer time period, annual bank-erosion rates were about 3.1 Mt/y, about 18 times greater than the value predicted by SedNet. Assuming 100 years of simulation and using an empirical relation between the length of BSTEM simulations and calculated erosion rates, a conservative value for the annual rate of bank erosion is 2.0 Mt/y. The BSTEM results and analysis of aerial imagery are within 10%. Bank erosion, instead of being a minor source of sediment representing 8% of the total, was found to be the single largest contributor, representing between 44 and 73% of the total annual sediment budget. In absolute terms, this is an increase in the reported average, annual rate of bank erosion from 0.175 Mt/y to 2.0 Mt/y. The significance of bank erosion to total, fine-grained sediment loads are drastically different than those reported for the Burnett and other Reef Catchments where fields and uplands are listed as the leading sediment contributors. These results pose important implications for sediment management and protection of the GBR.

  2. Modeling the influence of river rehabilitation scenarios on bed material sediment flux in a large river over decadal timescales

    USGS Publications Warehouse

    Singer, M.B.; Dunne, T.

    2006-01-01

    A stochastic flood generator and calibrated sediment transport formulae were used to assess the decadal impact of major river rehabilitation strategies on two fraction bed material sediment flux and net storage, first-order indicators of aquatic riverine habitat, in a large river system. Model boundary conditions were modified to reflect the implementation of three major river rehabilitation strategies being considered in the Sacramento River Valley: gravel augmentation, setting back of levees, and flow alteration. Fifty 30-year model simulations were used to compute probabilities of the response in sediment flux and net storage to these strategies. Total annual average bed material sediment flux estimates were made at six gauged river cross sections, and ???60 km reach-scale sediment budgets were evaluated between them. Gravel augmentation to improve spawning habitat induced gravel accumulation locally and/or downstream, depending on the added mixture. Levee setbacks to recreate the river corridor reduced flow stages for most flows and hence lowered sediment flux. Flow alteration to mimic natural flow regimes systematically decreased total annual average flux, suggesting that high-magnitude low-frequency transport events do not affect long-term trends in bed material flux. The results indicate that each rehabilitation strategy reduces sediment transport in its target reaches and modulates imbalances in total annual bed material sediment budgets at the reach scale. Additional risk analysis is necessary to identify extreme conditions associated with variable hydrology that could affect rehabilitation over decades. Sensitivity analysis suggests that sorting of bed material sediment is the most important determinant of modeled transport and storage patterns. Copyright 2006 by the American Geophysical Union.

  3. Temporal and spatial variations in estuarine sedimentation

    Microsoft Academic Search

    John McManus

    1998-01-01

    Sedimentation in estuaries is normally viewed as a continuous process controlled by inputs of fluvial and marine materials,\\u000a which migrate in response to tidal circulation. Short-term examination yields reproducible and measurable rates of sedimentation;\\u000a measurement of annual cycles reveals that sediment may be eroded from a site normally subject to deposition. Likewise annual\\u000a migration patterns of turbidity maximum zones permits

  4. Sediment dynamics in the restored reach of the Kissimmee River Basin, Florida: A vast subtropical riparian wetland

    USGS Publications Warehouse

    Schenk, E.R.; Hupp, C.R.; Gellis, A.

    2012-01-01

    Historically, the Kissimmee River Basin consisted of a broad nearly annually inundated riparian wetland similar in character to tropical Southern Hemisphere large rivers. The river was channelized in the 1960s and 1970s, draining the wetland. The river is currently being restored with over 10?000 hectares of wetlands being reconnected to 70 river km of naturalized channel. We monitored riparian wetland sediment dynamics between 2007 and 2010 at 87 sites in the restored reach and 14 sites in an unrestored reference reach. Discharge and sediment transport were measured at the downstream end of the restored reach. There were three flooding events during the study, two as annual flood events and a third as a greater than a 5-year flood event. Restoration has returned periodic flood flow to the riparian wetland and provides a mean sedimentation rate of 11.3?mm per year over the study period in the restored reach compared with 1.7?mm per year in an unrestored channelized reach. Sedimentation from the two annual floods was within the normal range for alluvial Coastal Plain rivers. Sediment deposits consisted of over 20% organics, similar to eastern blackwater rivers. The Kissimmee River is unique in North America for its hybrid alluvial/blackwater nature. Fluvial suspended-sediment measurements for the three flood events indicate that a majority of the sediment (70%) was sand, which is important for natural levee construction. Of the total suspended sediment load for the three flood events, 3%–16% was organic and important in floodplain deposition. Sediment yield is similar to low-gradient rivers draining to the Chesapeake Bay and alluvial rivers of the southeastern USA. Continued monitoring should determine whether observed sediment transport and floodplain deposition rates are normal for this river and determine the relationship between historic vegetation community restoration, hydroperiod restoration, and sedimentation.

  5. Two periods of total testicular regression are peculiar events of the annual reproductive cycle of the black Myotis bat, Myotis nigricans (Chiroptera: Vespertilionidae).

    PubMed

    Beguelini, Mateus R; Góes, Rejane M; Taboga, Sebastião R; Morielle-Versute, Eliana

    2014-01-01

    Myotis nigricans presents few and controversial reproductive data, which indicate geographical variation in reproduction. Thus, this study aimed to evaluate the seasonal modifications in testicular and epididymal morphologies in a tropical environment, submitting these organs to morphometric and immunohistochemical analysis. The observations revealed that this species presents two peaks of spermatogenic activity followed by two periods of total testicular regression (a quiescent pre-pubertal-like morphology, where only Sertoli cells and spermatogonia could be observed), in the same annual reproductive cycle, which seem to be only indirectly influenced by abiotic factors. This testicular behaviour seems to be synchronised with the caput and corpus epididymidis, but not with the cauda epididymidis, which presents aspects of sperm storage in May-June. The control of this variation seems to be directly linked to the expression of the androgen receptor, since, throughout the year, it is high in periods of testicular recrudescence and low in periods of deactivation. It is not thought to be directly linked to apoptosis, which is more pronounced in periods of recrudescence than in periods of regression. PMID:23830483

  6. Sediment deposition and occurrence of selected nutrients and other chemical constituents in bottom sediment, Tuttle Creek Lake, Northeast Kansas, 1962-99

    USGS Publications Warehouse

    Juracek, K.E.; Mau, D.P.

    2002-01-01

    A combination of bathymetric surveying and bottom-sediment coring was used to investigate sediment deposition and the occurrence of selected nutrients (total ammonia plus organic nitrogen and total phosphorus), 44 metals and trace elements, 15 organochlorine compounds, and 1 radionuclide in bottom sediment of Tuttle Creek Lake, northeast Kansas. The total estimated volume and mass of bottom sediment deposited from 1962 through 1999 in the original conservation-pool area of the lake was 6,170 million cubic feet (142,000 acre-feet) and 292,400 million pounds (133,000 million kilograms), respectively. The volume of sediment occupies about 33 percent of the original conservation-pool, water-storage capacity of the lake. Mean annual net sediment deposition since 1962 was estimated to be 7,900 million pounds (3,600 million kilograms). Mean annual net sediment yield from the Tuttle Creek Lake Basin was estimated to be 821,000 pounds per square mile (1,440 kilograms per hectare). The estimated mean annual net loads of total ammonia plus organic nitrogen and total phosphorus deposited in the bottom sediment of Tuttle Creek Lake were 6,350,000 pounds per year (2,880,000 kilograms per year) and 3,330,000 pounds per year (1,510,000 kilograms per year), respectively. The estimated mean annual net yields of total ammonia plus organic nitrogen and total phosphorus from the Tuttle Creek Lake Basin were 657 pounds per square mile per year (1.15 kilograms per hectare per year) and 348 pounds per square mile per year (0.61 kilograms per hectare per year), respectively. No statistically significant trend for total phosphorus deposition in the bottom sediment of Tuttle Creek Lake was indicated (trend analysis for total ammonia plus organic nitrogen was not performed). On the basis of available sediment-quality guidelines, the concentrations of arsenic, chromium, copper, nickel, silver, and zinc in the bottom sediment of Tuttle Creek Lake frequently or typically exceeded the threshold-effects levels established by the U.S. Environmental Protection Agency. Sediment concentrations of metals and trace elements were relatively uniform over time. Organochlorine compounds either were not detected or were detected at concentrations generally less than the threshold-effects levels. Following an initial positive trend, a statistically significant negative depositional trend was indicated for DDE (degradation product of DDT), which was consistent with the history of DDT use. Other organochlorine compounds detected included aldrin, DDD, and dieldrin. Notable changes in human activity within the basin included a substantial increase in the production of grain corn and soybeans from the 1960s to the 1990s. This increase in production was accompanied by a pronounced increase in the number of irrigated acres. Also, during the same time period, there was an overall increase in hog production. These changes in human activity have not had a discernible effect on the deposition of chemical constituents in the bottom sediment of Tuttle Creek Lake.

  7. Keeping agricultural soil out of rivers: evidence of sediment and nutrient accumulation within field wetlands in the UK.

    PubMed

    Ockenden, Mary C; Deasy, Clare; Quinton, John N; Surridge, Ben; Stoate, Chris

    2014-03-15

    Intensification of agriculture has resulted in increased soil degradation and erosion, with associated pollution of surface waters. Small field wetlands, constructed along runoff pathways, offer one option for slowing down and storing runoff in order to allow more time for sedimentation and for nutrients to be taken up by plants or micro-organisms. This paper describes research to provide quantitative evidence for the effectiveness of small field wetlands in the UK landscape. Ten wetlands were built on four farms in Cumbria and Leicestershire, UK. Annual surveys of sediment and nutrient accumulation in 2010, 2011 and 2012 indicated that most sediment was trapped at a sandy site (70 tonnes over 3 years), compared to a silty site (40 tonnes over 3 years) and a clay site (2 tonnes over 3 years). The timing of rainfall was more important than total annual rainfall for sediment accumulation, with most sediment transported in a few intense rainfall events, especially when these coincided with bare soil or poor crop cover. Nutrient concentration within sediments was inversely related to median particle size, but the total mass of nutrients trapped was dependent on the total mass of sediment trapped. Ratios of nutrient elements in the wetland sediments were consistent between sites, despite different catchment characteristics across the individual wetlands. The nutrient value of sediment collected from the wetlands was similar to that of soil in the surrounding fields; dredged sediment was considered to have value as soil replacement but not as fertiliser. Overall, small field wetlands can make a valuable contribution to keeping soil out of rivers. PMID:24509365

  8. 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-?m sieve and the <63-?m 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 with potential source materials and the target sediment show that the two radionuclides used in combination with the Corg property provide effective source fingerprints. Additional work using a mixing model taking account of particle size effects is required to establish the relative contributions of the three sources to the fine sediment loads of the study catchments. This research is supported by the Chilean Government through FONDECYT Project 1090574 and by the IAEA through CRP D1.20.11 (Contract CHI-15531 and Technical Contract 15478) and the RLA 05/051 Project.

  9. Sediment resuspension, redeposition, and focusing in a small dimictic reservoir

    USGS Publications Warehouse

    James, W.F.; Barko, J.W.

    1993-01-01

    Rates of seston (dry mass) sedimentation, estimated from sediment traps (ST rates) and sediment cores (SC rates), were determined at four water depths to examine seasonal and annual sedimentation patterns in Eau Galle Reservoir, Wisconsin (USA). Annual ST rates overestimated annual SC rates at water depths less-than-or-equal-to 4 m, suggesting that sediment resuspension and redeposition in relatively shallow regions of the reservoir caused the overestimate. In contrast, annual ST and SC rates were similar at depths >4 m, suggesting minimal sediment resuspension and redeposition in deeper regions of the reservoir. Using variations in daily ST rates estimated during the autumn overturn of 1987, we developed a conceptual framework for estimating sediment resuspension, redeposition, and focusing. Resuspension of shallow sediments during this particular period accounted for over 50% of the annual ST rate at depths less-than-or-equal-to 4 m. At the same time, focusing of resuspended shallow sediments to deeper regions accounted for about 20% of the annual ST rate at depths >4 m. Our results indicate that during autumn overturn in this reservoir, peaks in sedimentation in the deep, profundal region, estimated from sediment traps, may reflect sediment focused from shallow regions rather than sediment resuspended from the profundal region.

  10. Recent sedimentation events at the head of Saguenay Fjord, Canada

    NASA Astrophysics Data System (ADS)

    Schafer, Charles T.; Smith, John N.; Loring, Douglas H.

    1980-05-01

    Unbioturbated marine sediments containing a record of high river discharge events occur at the head of Saguenay Fjord, near Saint Fulgence, eastern Canada. Preservation of allochthonous benthonic foraminifera, recognition of occasional rapid sedimentation events associated with the spring runoff of the Saguenay River, and the unmixed character of the sediment can be used in conjunction with several dating techniques to obtain a temporal resolution of paleoriverine events on a time scale of months to years. The geologic and geochemical record of the upper 150 cm of sediment reflects (1) the anoxic character of the benthic environment, resulting from the high flux of terrigeneous material to the bottom; (2) the transport and deposition of landslide-derived sediment into the head of the fjord over several years; (3) an indication of the nature and timing of dissolution processes that have altered or totally eliminated the allochthonous calcareous microfossil assemblage from the recycled sediment; and (4) a cyclic depositional pattern that may be useful in reconstructing pateoclimatologic trends that have influenced annual river discharge of this drainage system over the past millennium.

  11. 17 CFR 270.30b1-2 - Semi-annual report for totally-owned registered management investment company subsidiary of...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...investment company need not file a semi-annual report on Form N-SAR if financial information with respect to that subsidiary is reported in the parent's semi-annual report on Form N-SAR. [54 FR 10321, Mar. 13,...

  12. 17 CFR 270.30b1-2 - Semi-annual report for totally-owned registered management investment company subsidiary of...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...investment company need not file a semi-annual report on Form N-SAR if financial information with respect to that subsidiary is reported in the parent's semi-annual report on Form N-SAR. [54 FR 10321, Mar. 13,...

  13. 17 CFR 270.30b1-2 - Semi-annual report for totally-owned registered management investment company subsidiary of...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...investment company need not file a semi-annual report on Form N-SAR if financial information with respect to that subsidiary is reported in the parent's semi-annual report on Form N-SAR. [54 FR 10321, Mar. 13,...

  14. 17 CFR 270.30b1-2 - Semi-annual report for totally-owned registered management investment company subsidiary of...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...investment company need not file a semi-annual report on Form N-SAR if financial information with respect to that subsidiary is reported in the parent's semi-annual report on Form N-SAR. [54 FR 10321, Mar. 13,...

  15. 17 CFR 270.30b1-2 - Semi-annual report for totally-owned registered management investment company subsidiary of...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...investment company need not file a semi-annual report on Form N-SAR if financial information with respect to that subsidiary is reported in the parent's semi-annual report on Form N-SAR. [54 FR 10321, Mar. 13,...

  16. Nitrogen turnover in drying sediments of an Amazon floodplain lake.

    PubMed

    Koschorreck, Matthias

    2005-05-01

    In the Amazon floodplain large areas are subject to annual cycles of drying and rewetting. The turnover of nitrogen in the periodically drying sediments is an important regulator of floodplain fertility. In the present study the transition of a lake sediment from flooded to dry conditions was studied with respect to microbial nitrogen turnover. Soil nitrogen pools, as well as the activity and abundance of denitrifying and nitrifying bacteria, were investigated during one dry season. During the first weeks after drying, most of the inorganic nitrogen vanished from the sediment. The process was inhibited by a nitrification inhibitor, showing that coupled nitrification-denitrification was responsible for the nitrogen loss. Assimilation by plants or microbes, as well as leaching, were not important mechanisms of nitrogen loss. During a period of only 10 days, 59% of the total denitrification and 94% of the total N2O emission during the dry period occurred. Cell numbers of denitrifiers were not correlated with activities. Denitrification was not correlated with other sediment variables but was regulated by the patchy distribution of reduced and oxidized zones in the uppermost centimeters of the sediment. This heterogeneity was probably introduced by the bioturbation of small insects, which was restricted to a rather short time period shortly after drying. PMID:16047095

  17. Annual dissolved nitrite plus nitrate and total phosphorous loads for the Susquehanna, St. Lawrence, Mississippi-Atchafalaya, and Columbia River basins, 1968-2004

    USGS Publications Warehouse

    Aulenbach, Brent T.

    2006-01-01

    Annual stream-water loads were calculated near the outlet of four of the larger river basins (Susquehanna, St. Lawrence, Mississippi-Atchafalaya, and Columbia) in the United States for dissolved nitrite plus nitrate (NO2 + NO3) and total phosphorus using LOADEST load estimation software. Loads were estimated for the period 1968-2004; although loads estimated for individual river basins and chemical constituent combinations typically were for shorter time periods due to limitations in data availability. Stream discharge and water-quality data for load estimates were obtained from the U.S. Geological Survey (USGS) with additional stream discharge data for the Mississippi-Atchafalaya River Basin from the U.S. Army Corps of Engineers. The loads were estimated to support national assessments of changes in stream nutrient loads that are periodically conducted by Federal agencies (for example, U.S. Environmental Protection Agency) and other water- and land-resource organizations. Data, methods, and results of load estimates are summarized herein; including World Wide Web links to electronic ASCII text files containing the raw data. The load estimates are compared to dissolved NO2 + NO3 loads for three of the large river basins from 1971 to 1998 that the USGS provided during 2001 to The H. John Heinz III Center for Science, Economics and the Environment (The Heinz Center) for a report The Heinz Center published during 2002. Differences in the load estimates are the result of using the most up-to-date monitoring data since the 2001 analysis, differences in how concentrations less than the reporting limit were handled by the load estimation models, and some errors and exclusions in the 2001 analysis datasets (which resulted in some inaccurate load estimates).

  18. Distributed Hydrology Soil Vegetation Model (DHSVM) and Sediment Discharge Validation in a small, Pacific Northwestern Watershed

    NASA Astrophysics Data System (ADS)

    Huggett, B. W.; Stubblefield, A. P.; Dhakal, A. S.; Sullivan, K.

    2009-12-01

    The Distributed Soil Vegetation Model (DHSVM) and its sediment production prediction capabilities are evaluated in a small, gaged, timber-production watershed in northwestern California. McReady Creek drains a 5 km2 basin dominated by coastal redwood (Sequoia sempervirens). Forest soils are fine grained and poorly consolidated marine sediments approximately 40 kya. Stream and sediment discharge data collected by Humboldt State University and Humboldt Redwoods Company (HRC) from 2003 to present were used to calibrate and validate DHSVM. Model parameters like forest stand (over- and understory height, fractional coverage, monthly LAI, etc) and soil characteristics (porosity, bulk density, field capacity, etc) were measured via in-field investigations or gathered by HRC through timber cruising activities. All data was gridded to 10 meters for the analysis. Forest stand data was manipulated throughout the model run to reflect the operational nature of the watershed. Modeled stream discharge will be evaluated against observed discharge on an event by event basis, as well as against weekly and monthly totals. Modeled sediment discharge will be evaluated on a similar basis, including total annual sediment discharge. Sources of potential incoherence between modeled and observed data may be road density (6.7 km / km2) and road/stream connectivity or the presence of legacy forest practices that still produce sediment within the basin. Further work will involve field investigations that will clarify road/stream connectivity and legacy sediment production zones.

  19. Runoff and sediment-associated nutrient losses under different land uses in Tigray, Northern Ethiopia

    NASA Astrophysics Data System (ADS)

    Girmay, G.; Singh, B. R.; Nyssen, J.; Borrosen, T.

    2009-09-01

    SummaryNutrient transport in surface runoff associated with sediment constitutes an important nutrient loss in Tigray, Northern Ethiopia, but little information is available on this aspect. This paper analyses runoff coefficient, runoff volume, sediment yield and sediment-associated nutrient losses under different land uses (cultivated, grazing, eucalyptus plantation, and exclosure lands) in the Tigray highlands. Two years data on rainfall, runoff volume, sediment yield and sediment-associated nutrient losses were collected from 31 runoff plots of 20 m 2. Results show that runoff coefficient, runoff volume and sediment yield are significantly higher in cultivated land than in the other land uses. On average, runoff volume from cultivated land is two times higher than in open grazing land at Gum Selassa, but at Maileba it is 5, 6, 16 times higher than in plantation, open grazing, and exclosures, respectively when extreme rainfall events were excluded. The respective values for sediment yield from cultivated land at Maileba are 4, 5 and 27 times higher. Variation in total rainfall amount that produced runoff explained 69% of the annual runoff volume variability, and this in turn explained 76% of the annual sediment yield variability. Among the plot variables, vegetation ground cover was significantly and negatively correlated with runoff coefficient; and runoff generation tends to be negligible when the ground cover exceeds 72%. Concentration of sediment-associated nutrient losses decreased with increasing sediment yield, supposedly related to the important nutrient dissolution effect of high runoff volumes. Rainfalls with low amount and intensity are important for selective removal of nutrient-rich sediments. Annually, on average, nutrient and OC losses varied between 14.4 and 263.4 kg ha -1 y -1 for OC, 2.1-32.8 kg ha -1 y -1 for N, 0.02-0.2 kg ha -1 y -1 for available P and 0.35-5.25 kg ha -1 y -1 for available K, with the lowest values in all cases on exclosures and highest on cultivated land. The present study demonstrates the effectiveness of exclosures and plantation in controlling runoff, sediment and sediment-associated nutrient losses on steep degrading lands of the region.

  20. From agricultural intensification to conservation: Sediment transport in the Raccoon River, Iowa, 1916-2009

    USGS Publications Warehouse

    Jones, C.S.; Schilling, K.E.

    2011-01-01

    Fluvial sediment is a ubiquitous pollutant that negatively aff ects surface water quality and municipal water supply treatment. As part of its routine water supply monitoring, the Des Moines Water Works (DMWW) has been measuring turbidity daily in the Raccoon River since 1916. For this study, we calibrated daily turbidity readings to modern total suspended solid (TSS) concentrations to develop an estimation of daily sediment concentrations in the river from 1916 to 2009. Our objectives were to evaluate longterm TSS patterns and trends, and relate these to changes in climate, land use, and agricultural practices that occurred during the 93-yr monitoring period. Results showed that while TSS concentrations and estimated sediment loads varied greatly from year to year, TSS concentrations were much greater in the early 20th century despite drier conditions and less discharge, and declined throughout the century. Against a backdrop of increasing discharge in the Raccoon River and widespread agricultural adaptations by farmers, sediment loads increased and peaked in the early 1970s, and then have slowly declined or remained steady throughout the 1980s to present. With annual sediment load concentrated during extreme events in the spring and early summer, continued sediment reductions in the Raccoon River watershed should be focused on conservation practices to reduce rainfall impacts and sediment mobilization. Overall, results from this study suggest that eff orts to reduce sediment load from the watershed appear to be working. ?? 2011 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.

  1. Background Radioactivity in River and Reservoir Sediments near Los Alamos, New Mexico

    SciTech Connect

    S.G.McLin; D.W. Lyons

    2002-05-05

    As part of its continuing Environmental Surveillance Program, regional river and lake-bottom sediments have been collected annually by Los Alamos National Laboratory (the Laboratory) since 1974 and 1979, respectively. These background samples are collected from three drainage basins at ten different river stations and five reservoirs located throughout northern New Mexico and southern Colorado. Radiochemical analyses for these sediments include tritium, strontium-90, cesium-137, total uranium, plutonium-238, plutonium-239,-240, americium-241, gross alpha, gross beta, and gross gamma radioactivity. Detection-limit radioactivity originates as worldwide fallout from aboveground nuclear weapons testing and satellite reentry into Earth's atmosphere. Spatial and temporal variations in individual analyte levels originate from atmospheric point-source introductions and natural rate differences in airborne deposition and soil erosion. Background radioactivity values on sediments reflect this variability, and grouped river and reservoir sediment samples show a range of statistical distributions that appear to be analyte dependent. Traditionally, both river and reservoir analyte data were blended together to establish background levels. In this report, however, we group background sediment data according to two criteria. These include sediment source (either river or reservoir sediments) and station location relative to the Laboratory (either upstream or downstream). These grouped data are statistically evaluated through 1997, and background radioactivity values are established for individual analytes in upstream river and reservoir sediments. This information may be used to establish the existence and areal extent of trace-level environmental contamination resulting from historical Laboratory research activities since the early 1940s.

  2. Total Organic Carbon (TOC) of Lake Water During the Holocene Inferred from Lake Sediments and Near-infrared Spectroscopy (NIRS) in Eight Lakes from Northern Sweden

    Microsoft Academic Search

    Peter Rosén

    2005-01-01

    The aim of this study is to infer past changes in total organic carbon (TOC) content of lake water during the Holocene in\\u000a eight boreal forest, tree-limit and alpine lakes using a new technique – near-infrared spectroscopy (NIRS). A training set\\u000a of 100 lakes from northern Sweden covering a TOC gradient from 0.7 to 14.9 mg l?1 was used to establish a

  3. Rates of contemporary overbank sedimentation and sediment storage on the floodplains of the main channel systems of the Yorkshire Ouse and River Tweed, UK

    NASA Astrophysics Data System (ADS)

    Walling, Desmond E.; Owens, Philip N.; Leeks, Graham J. L.

    1999-05-01

    Rates of contemporary overbank sedimentation and sediment storage on the floodplains of the main channel systems of the Yorkshire Ouse and River Tweed, UK, have been investigated, so that the estimates of sediment flux obtained for these rivers within the framework of the LOIS Community Research Programme can be considered in relation to their overall suspended sediment budgets. Caesium-137 measurements have been used to establish the recent rates of accumulation of fine-grained overbank sediment deposits associated with sediment cores collected from a series of transects across the floodplains of the study rivers. Average annual sedimentation rates over the past 30-40 years estimated for individual cores ranged from 0 to c. 1·60 g cm-2 yr-1 in the Ouse Basin and from 0 to c. 0·70 g cm-2 yr-1 in the Tweed Basin. In general, highest accumulation rates occur closest to the channel and values decrease with increasing distance from the channel, although for some transects very low accumulation rates also occur near the channel. Average overbank sedimentation rates for individual transects ranged from 0·010 to 0·554 g cm-2 yr-1 in the Ouse Basin and from 0·016 to 0·218 g cm-2 yr-1 in the Tweed Basin, with the mean for all transects being 0·206 and 0·129 g cm-2 yr-1, respectively. The total annual storage of fine-grained sediment on the floodplains bordering the main channel systems of the study rivers have been estimated by extrapolating the sedimentation rates derived for the individual transects to the adjacent floodplain reaches and calculating the total mass of sediment deposited upstream of the tidal limits. The resulting values are 70 970 t for the River Ouse (including the River Wharfe) system and 43 920 t for the River Tweed. These values of floodplain storage have been compared with the annual suspended sediment loads at downstream gauging sites for 1995 and 1996 provided by the LOIS Core Monitoring Programme for the River Ouse and estimated from Harmonized Monitoring Programme data for the River Tweed. This comparison indicates that 39 and 40% of the total suspended sediment delivered to the main channel systems of the rivers Ouse (to Skelton) and Tweed (to Norham), respectively, is deposited and stored on their floodplains. For the River Wharfe, the conveyance loss is c. 50%, and this higher value is thought to reflect the low sediment loads recorded for 1995 and 1996, which are likely to underestimate the longer term average values with which the estimates of sediment storage should be compared. The results obtained have important implications for the interpretation of downstream suspended sediment fluxes in the study rivers in terms of sediment mobilization and transfer within the upstream drainage basin.

  4. ANNUAL REPORT. FIXATION MECHANISMS AND DESORPTION RATES OF SORBED CS IN HIGH-LEVEL WASTE CONTAMINATED SUBSURFACE SEDIMENTS: IMPLICATIONS TO FUTURE BEHAVIOR AND IN-GROUND STABILITY

    EPA Science Inventory

    Research is investigating mineralogic and geochemical factors controlling the desorption rate of 137Cs+ from subsurface sediments on the Hanford Site contaminated with different types of high-level waste. The project will develop kinetic data and models that describe the release ...

  5. ANNUAL PROGRESS REPORT. COLLOID GENESIS/TRANSPORT AND FLOW PATHWAY ALTERATIONS RESULTING FROM INTERACTIONS OF REACTIVE WASTE SOLUTIONS AND HANFORD VADOSE ZONE SEDIMENTS

    EPA Science Inventory

    The overall objective of this research is to improve our understanding on the effects of interactions between the tank waste solution and sediments on deep contaminant migration under Hanford Site conditions. This objective will be achieved through the following four tasks: (1) c...

  6. 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...

  7. AQUATIC SEDIMENTS

    EPA Science Inventory

    One hundred seventeen literature references in the area of freshwater sediments were abstracted and synthesized to produce a review of sediment-related research for the period November, 1975 through October, 1976. Research areas covered included sediment-water interchange, sampli...

  8. Suspended sediment and bedload in the First Broad River Basin in Cleveland County, North Carolina, 2008-2009

    USGS Publications Warehouse

    Hazell, William F.; Huffman, Brad A.

    2011-01-01

    A study was conducted to characterize sediment transport upstream and downstream from a proposed dam on the First Broad River near the town of Lawndale in Cleveland County, North Carolina. Streamflow was measured continuously, and 381 suspended-sediment samples were collected between late March 2008 and September 2009 at two monitoring stations on the First Broad River to determine the suspended-sediment load at each site for the period April 2008-September 2009. In addition, 22 bedload samples were collected at the two sites to describe the relative contribution of bedload to total sediment load during selected events. Instantaneous streamflow, suspended-sediment, and bedload samples were collected at Knob Creek near Lawndale, North Carolina, to describe general suspended-sediment and bedload characteristics at this tributary to the First Broad River. Suspended- and bedload-sediment samples were collected at all three sites during a variety of flow conditions. Streamflow and suspended-sediment measurements were compared with historical data from a long-term (1959-2009) streamflow station located upstream from Lawndale. The mean streamflow at the long-term streamflow station was approximately 60 percent less during the study period than the long-term annual mean streamflow for the site. Suspended-sediment concentrations and continuous records of streamflow were used to estimate suspended-sediment loads and yields at the two monitoring stations on the First Broad River for the period April 2008-September 2009 and for a complete annual cycle (October 2008-September 2009), also known as a water year. Total suspended-sediment loads during water year 2009 were 18,700 and 36,500 tons at the two sites. High-flow events accounted for a large percentage of the total load, suggesting that the bulk of the total suspended-sediment load was transported during these events. Suspended-sediment yields during water year 2009 were 145 and 192 tons per square mile at the two monitoring stations. Historically, the estimated mean annual suspended-sediment yield at the long-term streamflow station during the period 1970-1979 was 250 tons per square mile, with an estimated mean annual suspended-sediment load of 15,000 tons. Drought conditions throughout most of the study period were a potential factor in the smaller yields at the monitoring stations compared to the yields estimated at the long-term streamflow station in the 1970s. During an extreme runoff event on January 7, 2009, bedload was 0.4 percent, 0.8 percent, and 0.1 percent of the total load at the three study sites, which indicates that during extreme runoff conditions the percentage of the total load that is bedload is not significant. The percentages of the total load that is bedload during low-flow conditions ranged from 0.1 to 90.8, which indicate that the bedload is variable both spatially and temporally.

  9. Sediment toxicity test results for the Urban Waters Study 2010, Bellingham Bay, Washington

    USGS Publications Warehouse

    Biedenbach, James M.

    2011-01-01

    The Washington Department of Ecology annually determines the quality of recently deposited sediments in Puget Sound as a part of Ecology's Urban Waters Initiative. The annual sediment quality studies use the Sediment Quality Triad (SQT) approach, thus relying on measures of chemical contamination, toxicity, and benthic in-faunal effects (Chapman, 1990). Since 2002, the studies followed a rotating sampling scheme, each year sampling a different region of the greater Puget Sound Basin. During the annual studies, samples are collected in locations selected with a stratified-random design, patterned after the designs previously used in baseline surveys completed during 1997-1999 (Long and others, 2003; Wilson and Partridge, 2007). Sediment samples were collected by personnel from the Washington Department of Ecology, in June of 2010 and shipped to the U. S. Geological Survey (USGS) laboratory in Corpus Christi, Texas (not shown), where the tests were performed. Sediment pore water was extracted with a pneumatic apparatus and was stored frozen. Just before testing, water-quality measurements were made and salinity adjusted, if necessary. Tests were performed on a dilution series of each sample consisting of 100-, 50-, and 25-percent pore-water concentrations. The specific objectives of this study were to: * Extract sediment pore water from a total of 30 sediment samples from the Bellingham Bay, Washington area within a day of receipt of the samples. * Measure water-quality parameters (salinity, dissolved oxygen, pH, sulfide, and ammonia) of thawed pore-water samples before testing and adjust salinity, temperature and dissolved oxygen, if necessary, to obtain optimal ranges for the test species. * Conduct the fertilization toxicity test with pore water using sea urchin (Stronylocentrotus purpuratus) (S. purpuratus) gametes. * Perform quality control assays with reference pore water, dilution blanks and a positive control dilution series with sodium dodecyl sulfate (SDS) in conjunction with each test. * Determine which samples caused a significant decrease in percent fertilization success relative to the negative control.

  10. SURROGATE TECHNIQUES FOR SUSPENDED-SEDIMENT MEASUREMENT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Physical, chemical, and biological sediment damage in North America has been estimated to be up to $16 billion dollars annually. Accepted methods of collecting sediment data are labor intensive, expensive and may be of unknown accuracy due to the large spatial and temporal variability associated wi...

  11. Sediment budget and interannual variations of suspended sediment load in the Rio Cordon (Italy). Three decades of monitoring and investigations (1987-2014).

    NASA Astrophysics Data System (ADS)

    García-Rama, Adriana; Rainato, Riccardo; Mao, Luca; Picco, Lorenzo; Aristide Lenzi, Mario

    2015-04-01

    This work shows the results of 28 years of measurements carried out in the Rio Cordon catchment, an Alpine watershed where a measuring station continuously recorded water discharge, bedload and suspended sediment transport since 1987. Hourly values of discharge and suspended sediment transport (or 5 min interval during flood events) have been studied throughout the whole study period. Annual and seasonal variations of suspended sediment load during the study period were analyzed along with their contribution to the total sediment yield. Comparing these almost three decades, the highest suspended solid transport occurred in 1994, 2001, 1987, 1998, 2002 and 2009, during which it was 2521.5, 1568.5, 792, 745, 551 and 514.8 t year-1, respectively. Summer and autumn contributions were significant in 1989, 1994, 1996, 1998, 2002, and 2005; on the other hand 2001 was characterized by a snowmelt flood that generated almost all the suspended load. A notable variability of the suspended solid transport can be observed taking in count snowmelt floods. Also 1987, 2001, 2008, 2009 and 2010 are characterized by a very important role of this kind of runoff. Data collected in the Rio Cordon for 28 years show that 75.2% of the total sediment load (10597.8 t of 14088.8 t) was due to suspended sediment transport. In 1994 and 2001, a large portion of the suspended sediment load was mainly supplied during the flood events that occurred in September 1994 and May 2001, which produced 198 and 1017.5 t respectively. Averaging 28 years of data, the mean annual specific sediment yield turns out to be around 102,9 t km-2 year-1. However, this value includes the 1986-1993 period characterized by ordinary flood events during which de mean sediment production was 65.34 t km-2 year-1, the massive sediment yield in 1994 (803.4 t km-2 year-1), the 1995-2000 period (93.2 t km-2 year-1), the 2001 (343.8 km-2 year-1) and the 2002-2014 period(54.5 t km-2 year-1). The highest values correspond to 1994, 2001, 1998 and 1987, respectively. Sediment availability decreased during the latest ten years, in which only snowmelt floods contributed significantly to the total suspended sediment yield. The reduction of the annual sediment budget in this period indicates an armoring process that is taking place in the riverbed. This research was funded by both Italian Research Project PRIN2010-2011-N° 20104ALME4-ITSE: National network for monitoring, modeling, and sustainable management of erosion processes in agricultural land and hilly-mountainous area and EU Project SedAlp: sediment management in Alpine basins, integrating sediment continuum, risk mitigation and hydropower, 83-4-3-AT.

  12. A sediment budget for the southern reach in San Francisco Bay, CA: implications for habitat restoration

    USGS Publications Warehouse

    Shellenbarger, Gregory G.; Wright, Scott A.; Schoellhamer, David H.

    2013-01-01

    The South Bay Salt Pond Restoration Project is overseeing the restoration of about 6000 ha of former commercial salt-evaporation ponds to tidal marsh and managed wetlands in the southern reach of San Francisco Bay (SFB). As a result of regional groundwater overdrafts prior to the 1970s, parts of the project area have subsided below sea-level and will require between 29 and 45 million m3 of sediment to raise the surface of the subsided areas to elevations appropriate for tidal marsh colonization and development. Therefore, a sufficient sediment supply to the far south SFB subembayment is a critical variable for achieving restoration goals. Although both major tributaries to far south SFB have been seasonally gaged for sediment since 2004, the sediment flux at the Dumbarton Narrows, the bayward boundary of far south SFB, has not been quantified until recently. Using daily suspended-sediment flux data from the gages on Guadalupe River and Coyote Creek, combined with continuous suspended-sediment flux data at Dumbarton Narrows, we computed a sediment budget for far south SFB during Water Years 2009–2011. A Monte Carlo approach was used to quantify the uncertainty of the flux estimates. The sediment flux past Dumbarton Narrows from the north dominates the input to the subembayment. However, environmental conditions in the spring can dramatically influence the direction of springtime flux, which appears to be a dominant influence on the net annual flux. It is estimated that up to several millennia may be required for natural tributary sediments to fill the accommodation space of the subsided former salt ponds, whereas supply from the rest of the bay could fill the space in several centuries. Uncertainty in the measurement of sediment flux is large, in part because small suspended-sediment concentration differences between flood and ebb tides can lead to large differences in total mass exchange. Using Monte Carlo simulations to estimate the random error associated with this uncertainty provides a more statistically rigorous method of quantifying this uncertainty than the more typical “sum of errors” approach. The results of this study reinforce the need for measurement of estuarine sediment fluxes over multiple years (multiple hydrologic conditions) to adequately detail the variability in flux. Additionally, the timing of breaching events for the restoration project could be tied to annual hydrologic conditions to capitalize on increased regional sediment supply.

  13. Diurnal variation in rates of calcification and carbonate sediment dissolution in Florida Bay

    USGS Publications Warehouse

    Yates, K.K.; Halley, R.B.

    2006-01-01

    Water quality and circulation in Florida Bay (a shallow, subtropical estuary in south Florida) are highly dependent upon the development and evolution of carbonate mud banks distributed throughout the Bay. Predicting the effect of natural and anthropogenic perturbations on carbonate sedimentation requires an understanding of annual, seasonal, and daily variations in the biogenic and inorganic processes affecting carbonate sediment precipitation and dissolution. In this study, net calcification rates were measured over diurnal cycles on 27 d during summer and winter from 1999 to 2003 on mud banks and four representative substrate types located within basins between mud banks. Substrate types that were measured in basins include seagrass beds of sparse and intermediate density Thalassia sp., mud bottom, and hard bottom communities. Changes in total alkalinity were used as a proxy for calcification and dissolution. On 22 d (81%), diurnal variation in rates of net calcification was observed. The highest rates of net carbonate sediment production (or lowest rates of net dissolution) generally occurred during daylight hours and ranged from 2.900 to -0.410 g CaCO3 m-2 d-1. The lowest rates of carbonate sediment production (or net sediment dissolution) occurred at night and ranged from 0.210 to -1.900 g CaCO3 m -2 night-1. During typical diurnal cycles, dissolution during the night consumed an average of 29% of sediment produced during the day on banks and 68% of sediment produced during the day in basins. Net sediment dissolution also occurred during daylight, but only when there was total cloud cover, high turbidity, or hypersalinity. Diurnal variation in calcification and dissolution in surface waters and surface sediments of Florida Bay is linked to cycling of carbon dioxide through photosynthesis and respiration. Estimation of long-term sediment accumulation rates from diurnal rates of carbonate sediment production measured in this study indicates an overall average accumulation rate for Florida Bay of 8.7 cm 1000 yr-1 and suggests that sediment dissolution plays a more important role than sediment transport in loss of sediment from Florida Bay. ?? 2006 Estuarine Research Federation.

  14. Laboratory-determined Phosphorus Flux from Lake Sediments as a Measure of Internal Phosphorus Loading

    PubMed Central

    Ogdahl, Mary E.; Steinman, Alan D.; Weinert, Maggie E.

    2014-01-01

    Eutrophication is a water quality issue in lakes worldwide, and there is a critical need to identify and control nutrient sources. Internal phosphorus (P) loading from lake sediments can account for a substantial portion of the total P load in eutrophic, and some mesotrophic, lakes. Laboratory determination of P release rates from sediment cores is one approach for determining the role of internal P loading and guiding management decisions. Two principal alternatives to experimental determination of sediment P release exist for estimating internal load: in situ measurements of changes in hypolimnetic P over time and P mass balance. The experimental approach using laboratory-based sediment incubations to quantify internal P load is a direct method, making it a valuable tool for lake management and restoration. Laboratory incubations of sediment cores can help determine the relative importance of internal vs. external P loads, as well as be used to answer a variety of lake management and research questions. We illustrate the use of sediment core incubations to assess the effectiveness of an aluminum sulfate (alum) treatment for reducing sediment P release. Other research questions that can be investigated using this approach include the effects of sediment resuspension and bioturbation on P release. The approach also has limitations. Assumptions must be made with respect to: extrapolating results from sediment cores to the entire lake; deciding over what time periods to measure nutrient release; and addressing possible core tube artifacts. A comprehensive dissolved oxygen monitoring strategy to assess temporal and spatial redox status in the lake provides greater confidence in annual P loads estimated from sediment core incubations. PMID:24637715

  15. Laboratory-determined phosphorus flux from lake sediments as a measure of internal phosphorus loading.

    PubMed

    Ogdahl, Mary E; Steinman, Alan D; Weinert, Maggie E

    2014-01-01

    Eutrophication is a water quality issue in lakes worldwide, and there is a critical need to identify and control nutrient sources. Internal phosphorus (P) loading from lake sediments can account for a substantial portion of the total P load in eutrophic, and some mesotrophic, lakes. Laboratory determination of P release rates from sediment cores is one approach for determining the role of internal P loading and guiding management decisions. Two principal alternatives to experimental determination of sediment P release exist for estimating internal load: in situ measurements of changes in hypolimnetic P over time and P mass balance. The experimental approach using laboratory-based sediment incubations to quantify internal P load is a direct method, making it a valuable tool for lake management and restoration. Laboratory incubations of sediment cores can help determine the relative importance of internal vs. external P loads, as well as be used to answer a variety of lake management and research questions. We illustrate the use of sediment core incubations to assess the effectiveness of an aluminum sulfate (alum) treatment for reducing sediment P release. Other research questions that can be investigated using this approach include the effects of sediment resuspension and bioturbation on P release. The approach also has limitations. Assumptions must be made with respect to: extrapolating results from sediment cores to the entire lake; deciding over what time periods to measure nutrient release; and addressing possible core tube artifacts. A comprehensive dissolved oxygen monitoring strategy to assess temporal and spatial redox status in the lake provides greater confidence in annual P loads estimated from sediment core incubations. PMID:24637715

  16. Sedimentation and pedogenesis in a Central Amazonian Black water basin

    Microsoft Academic Search

    A. Chauvel; I. Walker; Y. Lucas

    1996-01-01

    Sedimentation rates were estimated in a Central Amazonian Black-water inundation forest. Sediment deposition on the forest ground, remote from the river bed, during an annual flood period, is of the order of 1 to 10 tons per hectare, depending on water depth and duration of flooding. The sediments consisted of fine organic matter, kaolinite, quartz sands and biogenic particles of

  17. An integrated suspended sediment budgeting of the agricultural Can Revull catchment (Mallorca, Spain)

    NASA Astrophysics Data System (ADS)

    Estrany, J.; Garcia, C.

    2012-04-01

    The Mediterranean region of Europe has a long history of human settlement and human impacts. The very high spatial and temporal variability of fluvial processes in the region also creates problems for measurement and monitoring and for assessment of effects. Extensive rainfed herbaceous crops are one of the most representative agricultural elements of this region, which should be one of the major factor affecting erosion processes. Although land use is commonly seen as resulting in increased sediment yields, the implementation of soil and water conservation practices can have the reverse effect. Sediment budgets offer a means to assess the sources, storage, rates of transport, yields, and efficiency of delivery of sediment for a range of catchment scales. Field measurements were conducted in Can Revull, a small agricultural catchment (1.03 km2) on the island of Mallorca. This study uses 137Cs measurements, sediment source fingerprinting and continuous turbidity records of four hydrological years (2004-2005 to 2007-2008) to quantify the individual components of the budget. A large proportion of the material mobilized from cultivated fields without conservation practices (gross erosion was 775 t yr-1; 1,270 t km-2 yr-1) was, however, subsequently deposited either within the field of origin (112 t yr-1; 180 t km-2 yr-1) or at intermediate locations between the source field and the channel network (field-to-channel conveyance loss was 591 t yr-1; 1,090 t km-2 yr-1). The estimates of sediment accumulation rates on the floodplain in the lower reaches of the catchment indicate that the mean sedimentation rate was 0.47 g cm-2 yr-1. This value was extrapolated to the total area of the floodplain to estimate a total annual conveyance loss or storage of 150 t yr-1. Monitoring at the catchment outlet over the study period indicated a mean annual suspended sediment yield of 7 t km-2 yr-1. The sum of the estimates of sediment yield and floodplain storage (157 t yr-1) was taken to represent the total annual input of suspended sediment to the channel system. This value was subsequently apportioned using the information provided by the fingerprinting investigation, to estimate the mass of sediment reaching the channel network from cultivated fields and from eroding channel banks. Thus the annual contribution from channel banks was estimated to be 84 t yr-1. In the case of the contributions from cultivated fields, the estimates obtained were, as expected, significantly less than the values of net soil loss from these zones provided by the 137Cs measurements due to conveyance losses associated to field-to-channel conveyance loss. The overall sediment delivery ratios (<1%) indicate that approximately 99% of the sediment mobilized by erosion within the Can Revull catchment is subsequently deposited before reaching the monitoring station. As such, the low sediment outputs from the study catchment should be seen as reflecting the importance of conveyance losses and storage rather than a lack of sediment mobilization from the catchment surface, although part of the catchment headwaters was modified historically by means of terraces and transverse walls to prevent erosion.

  18. Runoff and Sediment Delivery from Bare and Graveled Forest Road Approaches to Stream Crossings

    NASA Astrophysics Data System (ADS)

    Brown, K. R.; McGuire, K. J.; Aust, W. M.

    2012-12-01

    Forested watersheds are typically associated with high quality water yield, yet forest roads and trails can adversely impact water quality draining forested watersheds. Increased stream sedimentation from forest road stream crossings often represents the most significant water quality threat associated with forestry operations. Quantification of sediment delivery rates is essential for the prescription of Best Management Practices (BMPs) that adequately address forest road stormwater runoff. Two different field experiments were implemented in the Virginia Piedmont to achieve the objectives of quantifying sediment delivery from forest roads where the road meets the stream (the road approach) and evaluating the sediment reduction efficacy of partially graveling road approaches. A forest operational experiment that included sediment traps and differential leveling was used to measure sediment delivery from five bare and four fully graveled road approaches for one year (August 2011 through July 2012). Rainfall simulation experiments were performed on six additional approaches to measure stormwater runoff volume, infiltration, and sediment delivery for 10 to 50-minute rain events with rainfall recurrence intervals of < 1 to 5-year return periods. Rainfall simulations were performed on newly-reopened bare approaches, with subsequent simulations on partially graveled approaches. The sediment trap study provides annual sediment delivery rates for bare and fully graveled road approaches. The rainfall simulation experiments characterize sediment delivery during storm events and provide an evaluation of different levels of Best Management Practice (BMP) implementation (i.e. ¼ to full gravel coverage) to minimize sediment inputs from road approaches. Sediment delivery from both experiments was related to rainfall amount, timing, and intensity, as well as road approach characteristics such as length, slope, and percentage of bare soil through stepwise multiple regression analysis. We found that the most important explanatory variables of sediment delivery over time are rainfall amount and approach length. Sediment delivery rates from the silt fence study ranged from 40 to 320 Mg ha-1 yr-1 for the bare approaches and from 11 to 20 Mg ha-1 yr-1 for the fully graveled approaches. Median total suspended solids (TSS) concentration of surface runoff during rainfall simulations ranged from 1.1-3.7, 1.1-2.0, and 0.2-1.1 g L-1, for the bare approach, first-, and second-gravel application treatments, respectively. These findings are particularly important for development and refinement of forestry BMPs as evidenced by recent and impending Federal court interpretations of the Clean Water Act. In addition, these controlled field experiments provide the data necessary to test model representation of hydrologic and soil erosion processes and to evaluate uncertainty in model predictions of runoff and sediment delivery.

  19. Long-term sediment yield of the Austdalsbreen glacier, southwest Norway

    NASA Astrophysics Data System (ADS)

    Xu, Mengzhen; Bogen, Jim; Ragulina, Galina; Read, Adrian

    2015-04-01

    Long-term sediment yield of Austdalsbreen glacier, an eastern outlet glacier of Jostedalsbreen ice cap in southwest Norway, was investigated by studies of sedimentation rates in the proglacial lakes Austdalsvatn and Styggevatn, along with subglacial topography radar survey and seismic surveys of the lake bed sediment. Sediment cores were taken from both lakes. Annual sedimentation throughout the cores was identified from high resolution photographs and X-ray scan analyses and was confirmed by three accelerator mass spectrometry (AMS) 14C datings. The seismic survey profiles revealed the distribution of these sediments. The impact of the subglacial topography on the sediment delivery from upstream, along with grain-size distribution and organic content analyses, were also taken into account in the interpretation of sediment cores. Possible impact of climate change on sediment delivery from the glacier was discussed by comparison of the average lake sedimentation rates during different periods of postglacial time. Around calibrated years 9000-8870 BP, Austdalsbreen glacier was subject to rapid retreat and calving. It was found that the glacier retreated rapidly from its maximum extension, which had totally covered the two lakes, in the 130 yrs in the early Holocene. About 1.4 million tons suspended load was delivered from the glacier during this short period, giving an average sediment yield of 400 t/yr km2. Such a high sediment yield was found to be due to rapid calving, fast ice motion, abundance of meltwater, and larger areal extension and volume of the glacier at that time. The glacier probably disappeared from the catchment around 6000 BP. The glacier advanced after the 1100s, reaching its Little Ice Age maximum before retreating to its present position. About 3.5 million tons suspended load was delivered from the glacier during the 800 yrs from 1186 to 1986 AD, corresponding to an average sediment yield of 290 t/yr km2, 30% lower than that of the early Holocene retreat. This difference is probably mostly due to the smaller volume of the modern glacier. Keywords: long-term sediment yield, postglacial time, proglacial lake, sediment core, seismic survey

  20. Aquatic sediments

    SciTech Connect

    DePinto, J.V.; Young, T.C.; Booty, W.G.

    1984-06-01

    This literature review includes conference proceedings on the interactions of PCBs. Papers range from the adsorption/desorption behavior of PCBs to the influence of suspended and benthic sediments on fate and transport modeling of PCBs in the Great Lakes. Other papers are included in the review which involve analytical and sampling methods, paleolimnology, and modeling and sediment transport. Two papers presented the results of using radionuclides (Pb-210, Ru-106, Cs-137) in the study of lake-sediment dynamics. 111 references.

  1. Predicting Sediment and Cesium-137 Transported to Offsite During Extreme Floods

    SciTech Connect

    Bao, Y.

    1999-04-12

    This paper presents the methods and results of a research project for predicting contaminated sediment transport from Oak Ridge Reservation to offside under potential extreme flood conditions. A computer model, Hydrologic Simulation Program--FORTRANE (HSPF), was calibrated and validated for White Oak Creek watershed using a five-year data. The model was then used to quantify the effects of a potential 100-year flood event in terms of the sediment transport and {sup 137}Cs movement. Results from computer simulation showed that during a 100-year flood event the watershed and channel bed became the major sources of the {sup 137}Cs. A 100-year flood event may result in 3.2 Ci of the total annual release of {sup 137}Cs which is six times of the averaged annual release observed during a five-year time period.

  2. Estimating suspended sediment and trace element fluxes in large river basins: Methodological considerations as applied to the NASQAN programme

    USGS Publications Warehouse

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

    2001-01-01

    In 1994, the NASQAN (National Stream Quality Accounting Network) programme was redesigned as a flux-based water-quality monitoring network for the Mississippi, Columbia, Colorado, and Rio Grande Basins. As the new programme represented a departure from the original, new sampling, processing, analytical, and data handling procedures had to be selected/developed to provide data on discharge, suspended sediment concentration, and the concentrations of suspended sediment and dissolved trace elements. Annual suspended sediment fluxes were estimated by summing daily instantaneous fluxes based on predicted suspended sediment concentrations derived from discharge-based log-log regression (rating-curve) models. The models were developed using both historical and current site-specific discharge and suspended sediment concentrations. Errors using this approach typically are less than ?? 10% for the 3-year reporting period; however, the magnitude of the errors increases substantially for temporal spans shorter than 1 year. Total, rather than total-recoverable, suspended sediment-associated trace element concentrations were determined by direct analysis of material dewatered from large-volume whole-water samples. Site-specific intra- and inter-annual suspended sediment-associated chemical variations were less (typically by no more than a factor of two) than those for either discharge or suspended sediment concentrations (usually more than 10-fold). The concentrations, hence the annual fluxes, for suspended sediment-associated phosphorus and organic carbon, determined by direct analyses, were higher than those determined using a more traditional paired, whole-water/filtered-water approach (by factors ranging from 1.5- to 10-fold). This may be important for such issues as eutrophication and coastal productivity. Filtered water-associated (dissolved) trace element concentrations were markedly lower than those determined during the historical NASQAN programme; many were below their respective detection limits. This resulted from the use of clean sampling, processing, and analytical protocols. Hence, the fluxes for filtered water-associated (dissolved) Ag, Pb, Co, V, Be, Sb, and Se, as well as the total (filtered water plus suspended sediment-associated) fluxes for these constituents, could not be estimated.

  3. Importance of elemental mercury in lake sediments

    Microsoft Academic Search

    Ariane Bouffard; Marc Amyot

    2009-01-01

    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 (Hg0) concentrations in sediments of two Canadian Shield lakes were assessed by thermodesorption. Hg0 concentrations in sediments varied between 6.3 and 60.3pgg?1 (wet weight) which represented 7.4–28.4% of total mercury (HgT) concentration.

  4. RELATIONSHIPS AMONG TOTAL LIPID, LIPID CLASSES AND POLYCHLORINATED BIPHENYL CONCENTRATIONS IN TWO INDIGENOUS POPULATIONS OF RIBBED MUSSELS (GUKENSIA DEMISSA) OVER AN ANNUAL CYCLE

    EPA Science Inventory

    Two indigenous ribbed mussel (Geukensia demissa) populations were sampled approximately every four weeks during 1997 to investigate the relationships among concentrations of total lipid, lipid classes, and polychlorinated biphenyls (PCBs). One population was located in a highly c...

  5. Aquatic sediments

    SciTech Connect

    Bonner, J.S.; Autenrieth, R.L.; Schreiber, L. (Texas A and M Univ., College Station (United States))

    1990-06-01

    The authors present a literature review concerning sediment properties, interactions, and conditions. Topics of discussion include the following: biological activity and toxicity; nutrients; metals; organic compounds; dredging; radionuclides; oxygen demand and organic carbon; mathematical modeling; sediment transport and suspension; and paleolimnology.

  6. Assessment of hydrology, suspended sediment and particulate organic carbon transport in a large agricultural catchment using SWAT model

    NASA Astrophysics Data System (ADS)

    Chantha, Oeurng; Sabine, Sauvage; José-Miguel, Sánchez-Pérez

    2010-05-01

    Suspended sediment transport from agricultural catchments to stream networks is responsible for aquatic habitat degradation, reservoir sedimentation and the transport of sediment-bound pollutants (pesticides, particulate nutrients, heavy metals and other toxic substances). Quantifying and understanding the dynamics of suspended sediment transfer from agricultural land to watercourses is essential in controlling soil erosion and in implementing appropriate mitigation practices to reduce stream suspended sediment and associated pollutant loads, and hence improve surface water quality downstream. Gascogne area, southwest France, has been dominated by anthropogenic activities particularly intensive agriculture causing severe erosion in recent decades. This leads to a major threat to surface water quality due to soil erosion. Therefore, the catchment water quality has been continuously monitored since January 2007 and the historical data of hydrology and suspended sediment has existed since 1998. In this study, the Soil and Water Assessment Tool (SWAT 2005) was applied to assess hydrology, suspended sediment and particulate organic carbon in this catchment Agricultural management practices (crop rotation, planting date, fertilizer quantity and irrigations) were taken into the model for simulation period of 11 years (July, 1998 to March, 2009). The investigation was conducted using a 11-year streamflow and two years of suspended sediment record from January 2007 to March 2009. Modelling strategy with dominant landuse and soil type was chosen in this study. The SWAT generally performs satisfactorily and could simulate both daily and monthly runoff and sediment yield. The simulated daily and monthly runoff matched the observed values satisfactorily (ENash>0.5). For suspended sediment simulation, the simulated values were compared with the observed continuous suspended sediment derived from turbidity data. Based on the relationship between SSC and POC (R2 = 0.93), POC was modelled by simulated SSC from SWAT. The model predicted that the average annual catchment rainfall of the 11-year evaluation period (726 mm) with evapotranspiration (78.3%), percolation/groundwater recharge (14.1%), transmission loss (0.5%), and yielding surface runoff (7.1%). The simulated average total water yield of 11 years accounted for 138 mm (observed=133mm) and annual sediment yield varying from 4766 t to 123000 t (Mean= 48 t km-2). The annual yield of particulate organic carbon ranged from 120 t to 3100 t (Mean=1.2 t km-2).

  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. Nutrient and suspended-sediment concentrations, trends, loads, and yields from the nontidal part of the Susquehanna, Potomac, Patuxent, and Choptank rivers, 1985-96

    USGS Publications Warehouse

    Darrell, Linda C.; Majedi, Brenda F.; Lizarraga, Joy S.; Blomquist, Joel D.

    1999-01-01

    The Chesapeake Bay River-Input Monitoring Program was established to characterize the water quality of four major rivers in Maryland, and to quantify the load and the long-term trends in concentrations of nutrients (nitrogen and phosphorus) and suspended sediment transported from the nontidal part of each river to the Chesapeake Bay. As part of the River-Input Monitoring Program, nutrient and suspended-sediment data and streamflow data were collected from 1985 through 1996 at the Susquehanna, Potomac, Patuxent, and Choptank Rivers above the points of tidal influence. The data were used to determine the effectiveness of strategies aimed at reducing nutrients entering Chesapeake Bay from its tributaries. Of the four rivers studied, the Patuxent River had the highest median concentrations of total nitrogen (2.6 milligrams per liter), total phosphorus (0.17 milligrams per liter), and suspended sediment (45 milligrams per liter) during the 12-year period. From 1985?96, flow-adjusted concentrations of total nitrogen decreased in all but the Potomac River, flow-adjusted concentrations of total phosphorus decreased in all four rivers, and flow-adjusted concentrations of suspended sediment decreased in all but the Susquehanna River. The rivers that contributed the greatest amount of streamflow to Chesapeake Bay, the Susquehanna and Potomac, also contributed the greatest nutrient loads and suspended-sediment loads to the Bay. The Susquehanna River transported the highest average-annual loads of total phosphorus (4.7 million pounds per year) and total nitrogen (146 million pounds per year), while the Potomac River transported the highest average-annual load of suspended sediment (4.1 billion pounds per year) to the Bay. Annual loads and annual mean streamflow were normalized by basin drainage area to account for some of the hydrologic differences among the river basins. An increase in precipitation from south to north is still apparent, however, when comparing the water yields among river basins. The Susquehanna River Basin had the highest median annual water yield during the study period; the other three basins all had similar water yields. The Susquehanna River and the Patuxent River had the highest median annual yields of nitrogen during the study period. The Patuxent River also had the highest median annual yield of total phosphorus during the study period, while the Potomac River had the highest median yield of suspended sediment. Annual yields of total phosphorus and suspended sediment from the Susquehanna and the Choptank River Basins are lower than those from the Potomac and Patuxent River Basins. These relatively small yields from the Susquehanna River may be due to the location of the sampling station below Conowingo Dam. A series of three dams upstream trap a large percentage of sediment and total phosphorus carried by the Susquehanna River to Chesapeake Bay.

  9. Cumulative sediment reduction to the Lower Mekong River from planned dams

    NASA Astrophysics Data System (ADS)

    Kondolf, G. M.; Rubin, Z.; Minear, J. T.; Alford, C.

    2012-12-01

    Cumulative sediment reduction to the Lower Mekong River from planned dams Kondolf, G.M.1, Rubin, Z.1, Alford, C.1 1University of California, Berkeley, USA T. Minear, US Geological Survey Essentially unregulated until the 1990s, the Mekong River system is now being rapidly changed by dam construction. On the Lancang River (the upper Mekong in China), a cascade of eight mainstem dams is under construction; on the Lower Mekong and tributaries, over 135 dams are planned or under construction. How will these dams alter the sediment load of the Mekong? Sediment data are lacking from important tributaries, and data from the better-sampled mainstem have data quality problems. Average annual suspended load of the entire Mekong is about 160 million tonnes per year (Mt/y) (Walling 2005), about half of which is derived from the Lancang drainage in China. Prior studies indicate that the eight Chinese dams will reduce sediment yield from the Lancang to the Lower Mekong River basin by 95%. Once the Lower Basin dams are built, what will be the likely cumulative reduction in sediment load? We first estimated sediment yields from tributaries to the lower Mekong River by delineating distinct geomorphic provinces, and based on geomorphic characteristics, the limited sediment sampling data available, and runoff, we reconstructed the unimpaired sediment loads for each tributary and each reach of the mainstem, such that the total load equaled the documented 160Mt/y. We next applied the 3W model of Minear and Kondolf (2009) (a network model that accounts for multiple reservoirs on a given river and changing trap efficiencies as reservoirs fill) to estimate the sediment trapping by various combinations of dams, from a near-term, 'definite-future' scenario to a full build-out scenario. Under the former scenario, the sediment load reaching the Delta will be about half of its pre-1990 level. With full build-out of dams in the Lower Mekong River basin, including mainstem dams, the sediment load reaching the Delta will be less than 5% of its pre-1990 load. This reduction will likely have profound implications for the productivity of agriculture and the fishery within the lower Mekong River and Delta, as well as the offshore fishery and the sustainability of the Delta landform itself. This reduction assumes no sediment bypass or pass-through strategies are implemented in these dams, but such measures could significantly reduce the sediment trapping and resulting sediment starvation.

  10. Biomarker evidence of Holocene climate and cryosphere variability: results from a 171m, annually laminated, sediment core from the Adélie coast, Antarctica (IODP Expedition 318)

    NASA Astrophysics Data System (ADS)

    Bendle, J. A.; Seki, O.; Kawamura, K.; Willmott, V.; Schouten, S.; Sangiorgi, F.; McKay, R.; Riesselman, C. R.; Dunbar, R. B.

    2012-12-01

    The Southern Ocean remains the least studied region on Earth with respect to Holocene climate variability. The few Antarctic proximal marine sedimentary records available tend to be short, low resolution, and discontinuous. However, sediments recently recovered from the Adélie drift during IODP Expedition 318 present a new opportunity to study East Antarctic Holocene climatic evolution, at a resolution that facilitates direct comparison with ice-cores. Expedition 318 recovered 171m of Holocene laminated diatom ooze from site U1357B. The sediments represent continuous Holocene accumulation up to the present day (based on 89 AMS 14C dates) and are characterised by 2-6cm thick, light/dark laminae couplets, interpreted as seasonal biogenic production and accumulation events. We present the results of initial biomarker analyses: fatty acid ?D and TEX86 measurements on lipid extracts from paired light/dark laminae throughout the Holocene. The C18 fatty acid is assumed to represent an integrated signal from the algal precursors and thus surface water conditions. The ?DC18-FA values show no consistent offset between the light and dark laminae, and values become isotopically heavier on average through the Holocene (ca. -220 to 140‰), in line with declining insolation at 65°S. Superimposed on this trend are millennial scale isotopic excursions of ca. 20 to 60‰, including a clear excursion coeval with an increase in grain size in U1356B and the late Holocene climate 'optimum' between 6 and 3 kyr, inferred from East Antarctic ice-cores. ?DC18-FA shows no clear relationship with TEXL86 sea-surface temperature estimates, which display pronounced early variability and relative warmth from 11.2 to 10.4 ka (0 to 6.5 °C, average ca. 3.5 °C), but almost no change after 10.4 ka, as cold, stable SSTs (average ca. 2 °C) persist through the rest of the Holocene. We explore the potential controls on the ?DC18-FA record and suggest the influence of isotopically depleted meltwater from the proximal ice-sheet (additive to a salinity effect) and/or upwelling could account for the millennial scale variability. The next steps are to ground-truth the proxies in this unique archive and to exploit the paleoclimatic information encoded in the abundant algal sterol compounds, the higher plant waxes and to apply compound-specific ?13C as well as additional ?D measurements.

  11. Sediment discharge from an area of highway construction, Applemans Run basin, Columbia County, Pennsylvania

    USGS Publications Warehouse

    Eckhardt, David A.V.

    1976-01-01

    The effects of highway construction on stream sediment loads were studied in Applemans Run basin, Columbia County, Pa., from October 1971 to May 1974. During the investigations, about 5,200 tons of suspended-sediment were discharged from the basin. Of this amount, about 2,700 tons, or about half the total sediment discharge, as derived from the highway construction area. Annual suspended-sediment yields from 17.5 acres under construction ranged from 40,000 to 66,000 tons/sq mi in the 1972 and 1973 water years, respectively. In the 1972 and 1973 er years of active construction, 83 percent of the sediment transported from the construction site was eroded each year in storms from January to June. Seasonal trends in sediment discharge for 1972 show that 69 percent of that year 's suspended-load was transported in April, May, and June, whereas less than 1 percent was transported in July, August, and September. (Woodard-USGS)

  12. Comparative seasonal changes, and inter-annual variability and stability, in a 26-year record of total phytoplankton biomass in four English lake basins

    Microsoft Academic Search

    J. F. Talling

    1993-01-01

    Long-term sequences of total phytoplankton biomass are described and analysed in relation to environmental conditions and species composition. They are based on largely weekly sampling of mean concentrations of chlorophyll a ([Chl]) in the euphotic zones of four English lake basins over 26 years. More restricted sampling is used to illustrate the regulation of vertical distribution, and a comparison with

  13. Allometric relations of total volumes of prolactin cells and corticotropic cells to body length in the annual cyprinodont Cynolebias whitei : effects of environmental salinity, stress and ageing

    Microsoft Academic Search

    J. M. Ruijter; S. E. Wendelaar Bonga

    1987-01-01

    An analysis of the allometric relations of the total volumes occupied by prolactin (PRL) and corticotropic (ACTH) cells (PRL volume and ACTH volume, respectively) to body length and a study of the immunocytochemical staining intensity of PRL and ACTH cells were used to determine the differences in activity of PRL and ACTH cells in freshwater-reared and in saltwater-reared Cynolebias whitei

  14. Sediment Flux and Fate of the Yangtze River Sediments Delivered to the East China Sea

    NASA Astrophysics Data System (ADS)

    Liu, P.; Li, A.; Yang, Z.; Xu, K.; Milliman, J. D.

    2004-12-01

    The continental shelf of the East China Sea (ECS), together with the Yellow Sea and Bohai Sea, forms a contiguous shelf of about 0.75\\times 1012 m2 in area. This wide( > 500 km) and shallow ( < 130 m) shelf also receives a large amount of terrigenous materials from two of the largest rivers in the world, the Yangtze River (Changjiang) and the Yellow River (Huanghe). The Yangtze River's annual sediment load has been about 480 million tons historically, combined with the adjacent Yellow River, equals more than 10% of the global total sediment flux to the ocean. Except for the part depositing in the river mouth, most fine sediment of the Yangtze River is believed to transport farther southward and accumulated offshore of Zhejiang and Fujian Provinces, which is commonly referred to as the "Mud belt deposit on the inner shelf of the ECS". However, for a long time, we have had no knowledge of the distribution, thickness, and sedimentary processes of this recent fine-grained deposit. In order to quantitatively define the Yangtze River's sediment transport and fate to the ocean, we conducted two geological and geophysical cruises in the summer of 2003 and 2004, with over 1000 km high-resolution Chirp sonar data, 8 gravity and box cores. The seismic profiles reveal a huge clinoform deposit off the coast of Zhejiang and Fujian Provinces, with a thickest ( ˜ 40 m) depocenter nearshore between the 20-30 m isobaths and progressively thins offshore (less than 100 km across the shelf) reaching water depths up 60 to 70 meters in the ECS. However, this Yangtze-derived mud wedge has also been found to transport southward at least 800 km from the river mouth, extending all the way into the middle of the Taiwan Strait where it possibly meets the Taiwan rivers-derived hyperpycnal mudflow. The total volume of this mud wedge is estimated to be about 1.2\\times 1012 m3, which is about 1.4\\times 1012 tons in total. Preliminary analysis of our seismic profiles and core data suggests that the Yangtze derived mud began to accumulate there only after the rapid sea-level rise of MWP-1B at around 11,000 yrs BP, when the sea level rose from -60 m to -40 m, together with the re-intensified Asian summer monsoon. But AMS C-14 dating suggest that major part of this mud has been transported southward along the shore since only about 7000 yrs BP by the newly formed Chinese coastal current after sea level reached its mid-Holocene highstand. This suggests that 2\\times 108 tons of sediment could be discharged annually southward from the river to the inner shelf, mainly in the winter season, which equals to nearly 50% of the current annual Yangtze's sediment discharge. The other half has been believed to be trapped in its estuary. The existing Taiwan Warm Current in the middle shelf and Kuroshio Current in the outer-middle shelf are also believed to play critical roles in blocking any Yangtze and Yellow-derived materials from being delivered further into the deep ocean.

  15. Quantifying sediment connectivity in Wadi Al-Arab (NW Jordan) using a sediment budget approach

    NASA Astrophysics Data System (ADS)

    Kraushaar, Sabine; Pöppl, Ronald

    2015-04-01

    Due to data scarcity, sediment connectivity most often only qualitatively describes the potential transfer of sediments through a landscape. However, quantitative information on sediment delivery is of special relevance for modelling approaches as well as for sustainable land and water management, especially in water scarce regions such as Jordan, where valuable water reservoirs suffer from sediment pollution. Measurements are needed to quantify sediment outputs of the different land units and to trace their pathways though the catchments. This study uses the outcomes of a multiple response sediment budget approach conducted in the Wadi al-Arab catchment in northwest Jordan (263.5 km²) to quantify sediment connectivity. The catchment shows a Mediterranean to semi arid climate and consists of carbonatic and marly geology of the Upper Cretaceous. The topography ranges from rolling hills in the East to steeper mountainous areas in the North and West were olive orchards are the main agricultural use. Soil erosion measurements in the main land use units and relevant sediment sources, such as olive orchards, agricultural fields, and natural vegetated slopes uncovered the potential ranges of soil erosion rates in these units. Furthermore, the annual sediment yield in the Wadi Al Arab water reservoir was calculated. With the extrapolation of the erosion rates of the main contributing land use units and the annual sediment amount that reaches the sink, a maximum value of lateral sediment connectivity could be quantified, reaching up to 18%. A multiple sediment fingerprint method was used to delineate the relative contribution of each measured source to the sink based on the lake sediment samples. Supported by additional 137Cs analysis of terrace samples and a survey of the Wadi bed a high longitudinal connectivity could be derived. The applied method mix allowed the quantification of lateral sediment connectivity on catchment scale and gave a comprehensive understanding of the longitudinal connectivity in the Wadi bed, this way serving as possible data base to test available sediment connectivity models.

  16. Distribution and partitioning of heavy metals in estuarine sediment cores: implications for sediment quality standards Hydrology and Earth System Sciences, 6(6), 989998 (2002) EGS

    E-print Network

    Paris-Sud XI, Université de

    2002-01-01

    Distribution and partitioning of heavy metals in estuarine sediment cores: implications and partitioning of heavy metals in estuarine sediment cores and implications for the use of sediment quality.spencer@gl.rhul.ac.uk Abstract Total metal concentrations in surface sediments and historically contaminated sediments were

  17. Sediment Transport

    NSDL National Science Digital Library

    Karen Williams

    Each student reviews a recent USGS publication detailing sediment transport data collection and reduction on the Yellowstone River. Using that report, they answer a series of questions about sediment transport and make some basic hydrologic and hydraulic calculations using data in the report. They also use USGS software to analyze cross-sections on the Yellowstone in a real world application. Designed for a geomorphology course

  18. Spatial variations of carbon, nitrogen, phosphorous and sulfur in the salt marsh sediments of the Yangtze Estuary in China

    NASA Astrophysics Data System (ADS)

    Zhou, Junli; Wu, Ying; Kang, Qinshu; Zhang, Jing

    2007-01-01

    Surface sediments and three sediment vibrocores were collected from the salt marsh of the Yangtze Estuary in order to examine the C, N, P and S distributions. Marsh plants and suspended particulate matter (SPM) from the river were also sampled and analyzed in order to determine their elemental compositions. The levels of total organic carbon (0.1-0.7%) and C/N ratios (6-11) in the surface sediments of the Yangtze Estuary salt marsh were relatively low compared with those reported for other salt marshes in European and North American coastal areas. The total organic carbon (TOC) level and C/N ratio of the surface sediments were similar to those of the SPM in the Yangtze Estuary, but were much lower than those of the marsh plant samples. These findings support the view that organic matter in the surface sediments is largely derived from SPM in the river, with minor contributions from the marsh vegetation. Total phosphorus (TP) showed irregular variation in its spatial distribution, whereas the TOC, total nitrogen (TN) and total sulfur (TS) concentrations were highest in the high marsh zones and lowest in the bare flat areas. This pattern was related to the spatial variability of the sediment grain size (i.e. clay-rich sediments in the high marsh zones resulted in elevated TOC, TN and TS contents). Some vibrocore sediments in the mid-depths of the high and low marsh zones, however, showed greater TOC contents than might have been predicted from the TOC-grain size relationship. This suggested the existence of additional organic inputs (i.e. marsh vegetation) for these vibrocore sediment sections, despite their original riverine source. After eliminating the effect of grain size, it was calculated that 22-55% of the TOC and 0.6-35% of the TN in the sediment samples were derived from the marsh vegetation. Considering both the vertical accretion rate and the ecosystem evolution of the salt marsh, it was estimated that the annual contributions of TOC and TN made by the marsh vegetation to the sediments in the Yangtze Estuary were 5.8 × 10 11 g C yr -1 and 2.3 × 10 10 g N yr -1, respectively, with corresponding accumulation rates of 1.1-1.5 × 10 10 g C yr -1 and 4.4-5.8 × 10 8 g N yr -1 at the present time.

  19. Routing Bedload Sediment Through River Networks Draining Steep Uplands

    NASA Astrophysics Data System (ADS)

    Cui, Y.; Dietrich, W. E.; Parker, G.

    2001-12-01

    River networks draining mountainous landscapes receive episodic and spatially variable sediment supply. The network structure itself imposes a distinct sediment loading structure in which steep, coarse bedded tributaries deliver significant point loads to less steep main stems. Landslides that fail directly into the main stem also introduce large local loads. These sediment pulses then become attenuated during downstream transport due to storage and particle breakdown. For both theoretical and practical reasons (e.g. dam removal, polluted sediment management, hillslope erosion management, and stream restoration) we need to be able to predict the downstream transit time of particles and quantify the controls on rates of signal attenuation downstream. Here we report a new, mechanistic numerical model for bedload routing that accounts for vertical storage, particle attrition, and stochastic sediment input and flow regime. The model uses observed channel slopes and channel widths. Flow is estimated through the network using drainage-area scaled annual flow duration. Sediment input varies around long-term average value by factors of a random number that co-varies with the randomly chosen flow duration curves and an independently selected random number, and input occurs along the channel banks and channel head. Debris flow transport is not considered. Simulations reported here were performed with data from the Noyo River, California as the prototype. Sample runs of the models revealed several important phenomena, many of which are fundamentally important in guiding future model development in mountain watersheds: a) in landscapes underlain by mechanically weak bedrock, particle attrition is probably the most important mechanism with which the bedload sediment is transported out of the system; b) due to particle attrition, bedload transport flux may decrease in the downstream direction even with the increased drainage area from tributary contributions, indicating the necessity for modifying the traditional sediment budget procedures in mountain watershed; c) coarse sediment pulses are damped by the stochastic driving flows and transient storage, leading to dispersion rather than translation, suggesting that the morphological response downstream of a sediment pulse is probably much smaller than generally expected, d) response times between introduction of an upstream load and arrival downstream is probably significantly shorter in channels where bedrock reaches are common, e) particle transit times are much shorter than celerity of the dampen sediment pulse, and f) although the network leads to significant downstream reduction in total boundary shear stress for a given flow, the grain size of the bed surface diminishes only slightly due to compensating effects of particle breakdown (reducing the total load), downstream widening channel bed area, and non-linear transport dependency on surface grain size. Further work is needed to account for lateral processes of transient channel width change in response to load fluctuations, the linkage between bank erosion and hillslope inputs, and the influence of debris flows. The model points to the need for field data on size distribution and strength properties of source sediment as well as the probability density function of sediment introduction across a landscape.

  20. Water Resources Center Annual Technical Report

    E-print Network

    in water resources, including the management of water resources among competing uses; controlling pollution Quality Focus Category: Water Quality, Sediments, Non Point Pollution Descriptors: AgricultureWater Resources Center Annual Technical Report FY 2001 Introduction Research Program Research

  1. A watershed-scale assessment of cost-effectiveness of sediment abatement with flow diversion terraces.

    PubMed

    Yang, Qi; Zhao, Zhengyong; Benoy, Glenn; Chow, Thien Lien; Rees, Herb W; Bourque, Charles P-A; Meng, Fan-Rui

    2010-01-01

    Soil conservation beneficial management practices (BMPs) are effective at controlling soil loss from farmlands and minimizing water pollution in agricultural watersheds. However, costs associated with implementing and maintaining these practices are high and often deter farmers from using them. Consequently, it is necessary to conduct cost-benefit analysis of BMP implementation to assist decision-makers with planning to provide the greatest level of environmental protection with limited resources and funding. The Soil and Water Assessment Tool (SWAT) was used to evaluate the efficacy of flow diversion terraces (FDT) in abating sediment yield at the outlet of Black Brook Watershed (BBW), northwestern New Brunswick. Different FDT-implementation scenarios were expressed as the ratio of land area protected by FDT to the total cultivated area. From this analysis, we found that average annual sediment yield decreased exponentially with increased FDT protection. When the proportion of FDT-protected areas was low, sediment reductions caused by FDT increased sharply with increasing use of FDT. Similarly, marginal sediment yield abatement costs (dollar per tonne of sediment reduction) increased exponentially with increasing proportion of FDT-protected area. The results indicated that increasing land protection with FDT from 6 to 50% would result in a reduction of about 2.1 tonne ha(-1) yr(-1) and costs of sediment reduction increased from $7 to $12 per tonne. Increasing FDT-protected cropland from 50 to 100%, a reduction of about 0.9 tonne of sediment ha(-1) yr(-1) would occur and the costs would increase from $12 to $53 per tonne of sediment yield reduction. PMID:20048309

  2. Two-dimensional sediment transport modeling for reservoir sediment management: Reventazón River, Costa Rica

    NASA Astrophysics Data System (ADS)

    Dubinski, I. M.

    2012-12-01

    Sedimentation is an ongoing concern for reservoirs that may be addressed using a variety of sediment management options. Sedimentation in reservoirs reduces reservoir storage and alters the sediment supply downstream. The objective of this study is to estimate the spatial and temporal distribution of deposited sediment in a proposed reservoir in the Reventazón River, Costa Rica over long-term operation (40 years) under different sediment management scenarios. The two-dimensional sediment transport model MIKE 21C by DHI is used to simulate sediment deposition for the base case (i.e., no sediment management) and assess the anticipated effectiveness of two sediment management strategies (i.e., full drawdown flushing and partial drawdown flushing). Incoming total sediment load is estimated using measured and estimated suspended sediment load combined with bed load estimated using the BAGS model with the Wilcock and Crowe (2003) equation. The base case simulation indicates that the anticipated storage loss in the absence of sediment management would amount to about 35% of the total and 33% of the active storage volume over a 40-year period. The predicted storage losses are significantly less when the performance of full drawdown flushing and partial drawdown flushing was simulated. In the case of full drawdown flushing the total anticipated storage loss is about 22%, while the loss in active storage is only 7%. In the case of partial drawdown flushing the predicted loss in total storage is 26%, while the anticipated loss in active storage is 8% after 40 years of operation. The simulations indicate that flushing is a viable and sustainable sediment management option for maintaining active storage in the proposed reservoir and passing through sediment.

  3. Sedimental Reasons

    NSDL National Science Digital Library

    Visitors to this site can view satellite imagery and read an account of how remote sensing was employed to evaluate the extent of flooding and sediment load in rivers on the coastal plain of North Carolina as a result of Hurricane Floyd in September, 1999. This feature is part of NASA's Earth Observatory, a publication that focuses on Earth's climate and environmental change.

  4. Sedimentation in arctic proglacial lakes: Mittivakkat Glacier, south-east Greenland

    NASA Astrophysics Data System (ADS)

    Hasholt, Bent; Walling, Desmond E.; Owens, Philip N.

    2000-03-01

    Several sediment cores were collected from two proglacial lakes in the vicinity of Mittivakkat Glacier, south-east Greenland, in order to determine sedimentation rates, estimate sediment yields and identify the dominant sources of the lacustrine sediment. The presence of varves in the ice-dammed Icefall Lake enabled sedimentation rates to be estimated using a combination of X-ray photography and down-core variations in 137Cs activity. Sedimentation rates for individual cores ranged between 0·52 and 1·06 g cm-2 year-1, and the average sedimentation rate was estimated to be 0·79 g cm-2 year-1. Despite considerable down-core variability in annual sedimentation rates, there is no significant trend over the period 1970 to 1994. After correcting for autochthonous organic matter content and trap efficiency, the mean fine-grained minerogenic sediment yield from the 3·8 km2 basin contributing to the lake was estimated to be 327 t km-2 year-1. Cores were also collected from the topset beds of two small deltas in Icefall Lake. The deposition of coarse-grained sediment on the delta surface was estimated to total in excess of 15 cm over the last c. 40 years. In the larger Lake Kuutuaq, which is located about 5 km from the glacier front and for which the glacier represents a smaller proportion of the contributing catchment, sedimentation rates determined for six cores collected from the centre of the lake, based on their 137Cs depth profiles, were estimated to range between 0·05 and 0·11 g cm-2 year-1, and the average was 0·08 g cm-2 year-1. The longer-term (sedimentation rate for one of the cores, estimated from its unsupported sedimentation rates in this lake have been essentially constant over the last sediment yield from the 32·4 kmsediment had accumulated on the delta surface over the last approximately 40 years. Caesium-137 concentrations associated with the most recently deposited (uppermost) fine-grained sediment in both Icefall Lake and Lake Kuutuaq were similar to those measured in fine-grained sediment collected from steep slopes in the immediate proglacial zone, suggesting that this material, rather than contemporary glacial debris, is the most likely source of the sediment deposited in the lakes. This finding is confirmed by the sediment collected from the Mittivakkat stream, which are very similar to those for proglacial material.

  5. Modern transport and deposition of settling particles in the northern South China Sea: Sediment trap evidence adjacent to Xisha Trough

    NASA Astrophysics Data System (ADS)

    Liu, Jianguo; Clift, Peter D.; Yan, Wen; Chen, Zhong; Chen, Han; Xiang, Rong; Wang, Dongxiao

    2014-11-01

    Studies on modern sediment transport and deposition, especially studies analyzing settling particles collected with sediment traps, have rarely been carried out in the northern South China Sea. Using sediment trap time series data from Site XS1 (17°24.5?N, 110°55.0?E, water depth 1690 m) adjacent to the Xisha Trough, variations in sediment source through time have been reconstructed. These observations include total particle flux (TPF) and current data, grain size distributions, and clay mineral compositions obtained from two sediment traps deployed in 500 m and 1500 m water depth, respectively. Time series records at Site XS1 changed seasonally for both sampled layers. TPF in the lower layer (426 mg/m2/d) was several times that of the upper layer (113 mg/m2/d) and is affected by lateral transport. However, mean grain size (Mz) of the upper layer is greater that of the lower layer (29 vs10 ?m) due to contributions from biogenic materials. There are no clear seasonal changes in clay mineral assemblage in either the upper or lower layers. The annual percentages of four main clay minerals were 82-83% illite, 7-9% kaolinite, 6-8% chlorite and 1-3% smectite. Taiwan was the dominant sediment source (42-74%), while sediment contributions from the Red River and Annamite Chain account for 23-53% and 0-15%, respectively. Sediment supply from Taiwan could be explained by deep water current flow, while coastal currents may aid sediment transport from the Red River and small mountainous rivers of central Vietnam.

  6. Notes on sedimentation activities calendar year 1992

    USGS Publications Warehouse

    U.S. Interagency Advisory Committee on Water Data- Subcommittee on Sedimentation

    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.

  7. Notes on sedimentation activities calendar year 1991

    USGS Publications Warehouse

    U.S. Interagency Advisory Committee on Water Data- Subcommittee on Sedimentation

    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.

  8. Notes on sedimentation activities calendar year 1990

    USGS Publications Warehouse

    U.S. Interagency Advisory Committee on Water Data- Subcommittee on Sedimentation

    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.

  9. Ammonia and sediment toxicity

    SciTech Connect

    Ogle, R.S.; Hansen, S.R. [S.R. Hansen and Associates, Concord, CA (United States)

    1994-12-31

    Ammonia toxicity to aquatic organisms has received considerable study, with most of these studies focusing on water column organisms. However, with the development and implementation of sediment (and pore water) toxicity tests, the toxicity of ammonia to benthic infauna and other sediment toxicity test organisms has become important, especially since sediment/porewater ammonia occurs at higher concentrations than in the water column. Unfortunately, there has been very little of this type information, especially for marine/estuarine organisms. This laboratory determined the toxicity of ammonia to three key marine/estuarine test organisms: the amphipod Eohaustorius estuarius, the bivalve Mytilus edulis, and the echinoderm Strongylocentrotus purpuratus. Because sediment/porewater pH can differ substantially from typical seawater pH, the toxicity evaluations covered a range of pH levels (6, 7, 8, and 9). Eohaustorius results indicate that while Total Ammonia increased in toxicity (measured as EC50) as pH increased (from 460 mg/L at pH 6, to 13 mg/L at pH 9), unionized ammonia toxicity decreased from 0.13 mg/L at pH 6 to 2.8 mg/L at pH 9. The amphipod was much less sensitive to ammonia than were the bivalve and echinoderm, with an unionized ammonia EC50 at pH 8 of 2.14 mg/L relative to 0.43 mg/L for the mussel and 0.13 mg/L for the purple urchin. These results are discussed with respect to design and interpretation of sediment toxicity test results, including an interpretation approach based on partitioning of Toxic Units (TU).

  10. Comment on "Wetland Sedimentation from Hurricanes Katrina and Rita"

    E-print Network

    Törnqvist, Torbjörn E.

    Comment on "Wetland Sedimentation from Hurricanes Katrina and Rita" Torbjörn E. Törnqvist,1 * Chris. (Reports, 20 October 2006, p. 449) measured sedimentation from Hurricanes Katrina and Rita in coastal, their annualized hurricane deposition rate is overestimated, whereas riverine deposition is underestimated

  11. Temporal trends in fluvial-sediment discharge in Ohio, 1950-1987

    USGS Publications Warehouse

    Hindall, S.M.

    1991-01-01

    Long-term fluvial-sediment records of annual suspended-sediment discharge data are available for eight daily suspended-sediment stations operated in Ohio. Graphical and statistical analyses of long-term sediment records indicate that, in general, no long-term (>3- to 5-year) trends are readily apparent in the relation between annual mean suspended-sediment discharge and water discharge in Ohio; however, some short-term, year-to-year changes in that relation occur for Ohio streams. Double-mass curves for five daily suspended-sediment stations and seasonal Kendall analysis of data from eight daily suspended-sediment stations clearly illustrate the lack of any discernible changes in the suspended-sediment-discharge/water-discharge relation or in suspended-sediment concentration for most Ohio streams over the past 36 years. -from Author

  12. 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 considering seasonal effects. Typically, sediment concentration is the highest during the warmest months. The infrequent high flows carry a large, disproportionate amount of sediment.

  13. Analysis of streamflow and sediment flux changes in the Yangtze River basin

    Microsoft Academic Search

    Guangju Zhao; Xingmin Mu; Buda Su; Peng Tian; Fei Wang; Jianqing Zhai; Ming Xiong

    2012-01-01

    The present paper focuses on the variation of the annual streamflow and sediment fluxes in the Yangtze River basin from 1956 to 2009 using annual observations at 10 hydrological gauging stations. Both simple linear regression analysis and the Mann-Kendall test are applied to the time series for trend detection, and the relations between streamflow and precipitation and between sediment flux

  14. Nashua Impoundment sediment sampling, June 1985

    Microsoft Academic Search

    Carleton

    1985-01-01

    The Iowa Department of Water, Air and Waste Management sampled the sediment of the Nashua Impoundment on the Cedar River in Chickasaw County during June, 1985. The sediment samples were analyzed using the Extraction Procedure (EP) Toxicity Test for eight heavy metals and six pesticides. The samples were also tested for total concentrations of cyanides, phenols, fluorides, chlorides, and eleven

  15. 76 FR 69239 - Annual Retail Trade Survey

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-08

    ...data covering annual sales, annual e-commerce sales, year-end inventories held...merchandise line sales, and percent of e-commerce sales to customers located outside...classification basis, annual sales, annual e-commerce sales, purchases, total...

  16. 77 FR 64463 - Annual Retail Trade Survey

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-22

    ...data covering annual sales, annual e- commerce sales, year-end inventories held...merchandise line sales, and percent of e-commerce sales to customers located outside...classification basis, annual sales, annual e-commerce sales, purchases, total and...

  17. 75 FR 63804 - Annual Retail Trade Survey

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-18

    ...data covering annual sales, annual e-commerce sales, year-end inventories held...class of customer, and percent of e-commerce sales to customers located outside...classification basis, annual sales, annual e-commerce sales, purchases, total...

  18. River sediments.

    PubMed

    Williams, Martin

    2012-05-13

    River history is reflected in the nature of the sediments carried and deposited over time. Using examples drawn from around the world, this account illustrates how river sediments have been used to reconstruct past environmental changes at a variety of scales in time and space. Problems arising from a patchy alluvial record and from influences external to the river basin can make interpretation difficult. The Nile is treated in some detail because its history is further complicated by tectonic, volcanic and climatic events in its headwaters and by enduring human impacts. It arose soon after 30 Ma. Since that time approximately 100,000 km(3) of rock have been eroded from its Ethiopian sources and deposited in the eastern Mediterranean, with minor amounts of sediment laid down along its former flood plains in Egypt and Sudan. From these fragmentary alluvial remains, a detailed history of Nile floods and droughts has been reconstructed for the last 15 kyr, and, with less detail, for the past 150 kyr, which shows strong accordance with global fluctuations in the strength of the summer monsoon, which are in turn perhaps modulated by changes in solar insolation caused by changes in the Earth's orbit and by variations in solar irradiance. PMID:22474677

  19. Total war

    Microsoft Academic Search

    Talbot Imlay

    2007-01-01

    This article reviews the five volume series, published by Cambridge University Press, on the history of total war from the American Civil War and Wars of German Unification to World War II. The discussion focuses on two questions: how to define total war; and is total war a useful conceptual tool for understanding warfare during this period? Although the editors

  20. Patterns and contributions of floodplain and legacy sediments remobilized from Piedmont streams of the mid-Atlantic U.S.

    NASA Astrophysics Data System (ADS)

    Donovan, Mitchell; Miller, Andrew; Baker, Matthew; Gellis, Allen

    2015-04-01

    The perceived role of streambank erosion as a contributor to watershed sediment yield is an important driver of policy decisions for managing downstream impacts in the United States. In the Piedmont physiographic province of the eastern U.S. and in other regions of the south and midwest, the issue of 'legacy' sediment stored in stream valleys has long been recognized as a consequence of rapid deforestation and erosive agricultural practices following European settlement. Remobilization of stored floodplain sediment by bank erosion is frequently cited as a dominant component of watershed sediment budgets, with legacy sediment comprising the largest portion of this source. However there are few published studies documenting spatially extensive measurements of channel change throughout the drainage network on time scales of more than a few years. In this study we document 1) rates of sediment remobilization from Baltimore County floodplains by channel migration and bank erosion, 2) proportions of streambank sediment derived from legacy deposits, and 3) potential contribution of net streambank erosion and legacy sediments to downstream sediment yield within the Mid-Atlantic Piedmont. We measured gross erosion and channel deposition rates over 45 years within the fluvial corridor along 40 valley segments from 18 watersheds with drainage areas between 0.18 and 155 km2 by comparing stream channel and floodplain morphology from LiDAR-based digital elevation data collected in 2005 with channel positions recorded on 1:2400-scale topographic maps from 1959-1961. Results were extrapolated to estimate contributions to watershed sediment yield from 1005 km2 of northern Baltimore County. Results indicate that legacy sediment is a dominant component (62%) of the sediment derived from bank erosion and that its relative importance is greater in larger valleys with broader valley floors and lower gradients. Although mass of sediment remobilized per unit channel length is greater in these downstream valleys, a majority of remobilized sediment (62%) is coming from first- and second-order tributaries because they represent the largest fraction of cumulative channel length in the drainage network. Floodplain segments are discontinuous along low-order tributaries but sediment contributions reported here are adjusted to account for the percent valley length bordered by floodplain sediments. Average annual lateral migration rates ranged from 0.04-0.19 m/y with higher rates along larger streams; however, when scaled by channel width, we find that on average streams are migrating 2.5% of channel width across all drainage areas. Direct measurements reported here account for in-channel deposition, but not floodplain deposition. Other studies in the region have demonstrated that redeposition on floodplains is an important component of the sediment budget and are necessary to avoid overestimating streambank erosion contributions to watershed sediment yield. We therefore adjust our measured sediment contributions by estimating the mass of sediment redeposited on floodplains within our study area. With this adjustment, extrapolated net stream bank sediment yields (72 Mg/km2/yr) are equivalent to 70% of the estimated average Piedmont watershed yield (104 Mg/km2/yr) cited by previous authors. Furthermore, our results demonstrate that measurements over adequate spatial and temporal scales- rather than short-term, localized observations- are required to accurately capture and measure patterns of streambank erosion across the drainage network. It is important to note that upland erosion rates- not measured here- have been reported with equivalent and greater magnitude for forested and cropland areas within the Maryland Piedmont and therefore should not be assumed to contribute only 30% of the total.

  1. Sediment export from the Sepik River, Papua New Guinea: evidence for a divergent sediment plume

    Microsoft Academic Search

    G. C Kineke; K. J Woolfe; S. A Kuehl; J. D Milliman; T. M Dellapenna; R. G Purdon

    2000-01-01

    The Sepik River, with an estimated annual sediment load of ?85×106tyr?1, empties directly into a submarine canyon that transverses a narrow continental shelf (<5km) on the north coast of Papua New Guinea. As such, it serves as a possible analogue for rivers discharging onto margins during low stands of sea level. A substantial portion of the riverine sediment appears to

  2. 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...

  3. Sedimentation of chlorophylls in an Arctic fjord under freshwater discharge

    Microsoft Academic Search

    Pawel Dobrzyn; Alexander Keck; Andrzej Tatur

    2005-01-01

    Sedimentation of chlorophylls was studied during summer 1997 in Adventfjorden (Spitsbergen, Arctic). During the period of study, the water column was found to be well stratified by a freshened surface layer (salinity m. Total particulate matter sedimentation rates were about twice as high in June as in July. The following chlorophylls were distinguished in the sedimented particles: chl a and

  4. Anaerobic Oxalate Degradation: Widespread Natural Occurrence in Aquatic Sediments

    PubMed Central

    Smith, Richard L.; Oremland, Ronald S.

    1983-01-01

    Significant concentrations of oxalate (dissolved plus particulate) were present in sediments taken from a diversity of aquatic environments, ranging from 0.1 to 0.7 mmol/liter of sediment. These included pelagic and littoral sediments from two freshwater lakes (Searsville Lake, Calif., and Lake Tahoe, Calif.), a hypersaline, meromictic, alkaline lake (Big Soda Lake, Nev.), and a South San Francisco Bay mud flat and salt marsh. The oxalate concentration of several plant species which are potential detrital inputs to these aquatic sediments ranged from 0.1 to 5.0% (wt/wt). In experiments with litter bags, the oxalate content of Myriophyllum sp. samples buried in freshwater littoral sediments decreased to 7% of the original value in 175 days. This suggests that plant detritus is a potential source of the oxalate within these sediments. [14C]oxalic acid was anaerobically degraded to 14CO2 in all sediment types tested, with higher rates evident in littoral sediments than in the pelagic sediments of the lakes studied. The turnover time of the added [14C]oxalate was less than 1 day in Searsville Lake littoral sediments. The total sediment oxalate concentration did not vary significantly between littoral and pelagic sediments and therefore did not appear to be controlling the rate of oxalate degradation. However, depth profiles of [14C]oxalate mineralization and dissolved oxalate concentration were closely correlated in freshwater littoral sediments; both were greatest in the surface sediments (0 to 5 cm) and decreased with depth. The dissolved oxalate concentration (9.1 ?mol/liter of sediment) was only 3% of the total extractable oxalate (277 ?mol/liter of sediment) at the sediment surface. These results suggest that anaerobic oxalate degradation is a widespread phenomenon in aquatic sediments and may be limited by the dissolved oxalate concentration within these sediments. PMID:16346332

  5. Impact of river regulation on potential sediment mobilization and transport in an Alpine catchment

    NASA Astrophysics Data System (ADS)

    Costa, Anna; Molnar, Peter; Lane, Stuart N.; Bakker, Maarten

    2015-04-01

    The upper Rhône basin (upstream of Lake Geneva) has been heavily affected by human activities during the last century. The most evident impacts are related to river regulation, specifically flow impoundement, flow abstraction and channelization. In the last century and mainly since 1960, several large dams have been built along the main tributaries of the Rhône River, resulting in the water storage of a volume equal to 20% of the total annual river flow. The dams are part of hydropower systems which abstract water from streams and transfer it through complex networks (intakes, tunnels and pumping stations) to the reservoirs. Hydropower production leads to regulated flow in the Rhône: mostly an increase of winter flows, a reduction of summer flows, and a decrease of flood peaks. The sediment supply into Lake Geneva has decreased following dam construction (Loizeau & Dominik, 2000) due to the storage of sediment in upstream reservoirs, in rivers with reduced sediment transport capacity due to flow abstraction, and due to the development of sediment mining. Our hypothesis is that streamflow regulation itself has dramatically impacted the sediment transport dynamics of the system. We investigate the impacts of flow regulation on the sediment transport regime, by analysing the effects on potential sediment transport capacity (bedload). By the use of different bedload transport formulae (Meyer-Peter Müller, Wilcock and Crowe), the potential sediment transport capacity is computed at different cross sections within the basin. Potential sediment mobility occurs when the applied bed shear stress exceeds a critical value, ?>?c. The applied bed shear stress is computed as ?=?ghS, with water depth (h) measured from rating curves. We obtain an estimate of the energy slope (S) from the analysis of the river cross section, assuming uniform flow. The critical value of bed shear stress ?c is computed using empirical formulae as a function of the grain diameter (ds). To identify the grain size-dependent effects of streamflow regulation, computations are applied to different grain sizes taken from grain size distributions of river bed sediment. The results show that flow regulation has indeed resulted in higher potential mobility of finer grain sizes during winter due to the increased flow, but not for the coarsest fractions which are mobilized only during summer high flows. Many studies of the impacts of major flow regulation have focused upon the effects of dams and flow diversions on sediment flux. In contrast, here we focus upon the effects of flow regulation on sediment transport potential downstream of a region of major flow regulation in an Alpine catchment. We show that the seasonal changes in streamflow arising from flow regulation impact upon sediment transport potential and these may be important in terms of the seasonal dynamics of sediment production (e.g. glacier erosion, landslides, rockfalls produced by heavy seasonal rainfall). In this context we also analyse suspended sediment concentration data and turbidity data at the outlet of the basin, in order to identify specific features of fine sediment production and transport processes. The present work is part of the research project SEDFATE funded by the SNF Sinergia Programme, which aims at quantifying the human impacts on the observed reduction of suspended sediment inflows to Lake Geneva.

  6. 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. PMID:26084967

  7. RAPID Assessment of Extreme Reservoir Sedimentation Resulting from the September 2013 Flood, North St. Vrain Creek, CO

    NASA Astrophysics Data System (ADS)

    Rathburn, S. L.; McElroy, B. J.; Wohl, E.; Sutfin, N. A.; Huson, K.

    2014-12-01

    During mid-September 2013, approximately 360 mm of precipitation fell in the headwaters of the North St. Vrain drainage basin, Front Range, CO. Debris flows on steep hillslopes and extensive flooding along North St. Vrain Creek resulted in extreme sedimentation within Ralph Price Reservoir, municipal water supply for the City of Longmont. The event allows comparison of historical sedimentation with that of an unusually large flood because 1) no reservoir flushing has been conducted since dam construction, 2) reservoir stratigraphy chronicles uninterrupted delta deposition, and 3) this is the only on-channel reservoir with unimpeded, natural sediment flux from the Continental Divide to the mountain front in a basin with no significant historic flow modifications and land use impacts. Assessing the flood-related sedimentation prior to any dredging activities included coring the reservoir delta, a bathymetric survey of the delta, resistivity and ground penetrating radar surveys of the subaerial inlet deposit, and surveying tributary deposits. Over the 44-year life of the reservoir, two-thirds of the delta sedimentation is attributed to extreme discharges from the September 2013 storm. Total storm-derived reservoir sedimentation is approximately 275,000 m3, with 81% of that within the gravel-dominated inlet and 17% in the delta. Volumes of deposition within reservoir tributary inlets is negatively correlated with contributing area, possibly due to a lack of storage in these small basins (1-5 km2). Flood-related reservoir sedimentation will be compared to other research quantifying volumes from slope failures evident on post-storm lidar. Analysis of delta core samples will quantify organic carbon flux associated with the extreme discharge and develop a chronology of flood and fire disturbances for North St. Vrain basin. Applications of similar techniques are planned for two older Front Range reservoirs affected by the September flooding to fill knowledge gaps about event-based sedimentation and to expand these rates to annual and decadal scales.

  8. Potential microbial bioinvasions via ships' ballast water, sediment, and biofilm.

    PubMed

    Drake, Lisa A; Doblin, Martina A; Dobbs, Fred C

    2007-01-01

    A prominent vector of aquatic invasive species to coastal regions is the discharge of water, sediments, and biofilm from ships' ballast-water tanks. During eight years of studying ships arriving to the lower Chesapeake Bay, we developed an understanding of the mechanisms by which invasive microorganisms might arrive to the region via ships. Within a given ship, habitats included ballast water, unpumpable water and sediment (collectively known as residuals), and biofilms formed on internal surfaces of ballast-water tanks. We sampled 69 vessels arriving from foreign and domestic ports, largely from Western Europe, the Mediterranean region, and the US East and Gulf coasts. All habitats contained bacteria and viruses. By extrapolating the measured concentration of a microbial metric to the estimated volume of ballast water, biofilm, or residual sediment and water within an average vessel, we calculated the potential total number of microorganisms contained by each habitat, thus creating a hierarchy of risk of delivery. The estimated concentration of microorganisms was greatest in ballast water>sediment and water residuals>biofilms. From these results, it is clear microorganisms may be transported within ships in a variety of ways. Using temperature tolerance as a measure of survivability and the temperature difference between ballast-water samples and the water into which the ballast water was discharged, we estimated 56% of microorganisms could survive in the lower Bay. Extrapolated delivery and survival of microorganisms to the Port of Hampton Roads in lower Chesapeake Bay shows on the order of 10(20) microorganisms (6.8 x 10(19) viruses and 3.9 x 10(18) bacteria cells) are discharged annually to the region. PMID:17215010

  9. Anthropogenic sediment resuspension mechanisms in a shallow microtidal estuary

    USGS Publications Warehouse

    Schoellhamer, D.H.

    1996-01-01

    The mechanisms that resuspend bottom sediments in Hillsborough Bay, a shallow, microtidal, subtropical estuary in West-central Florida, were determined by analysing hydrodynamic and suspended-solids concentration data collected during several instrument deployments made in 1990 and 1991. Large vessels in a dredged ship channel can generate forced solitary long waves that cause large water velocities and sediment resuspension at the study sites. An experiment was conducted with a trawler that resuspended bottom sediments, and some of the resuspended sediments remained in suspension for at least 8 h. A secondary impact of vessel-generated long waves and trawling is that sediments that are resuspended and newly deposited are more susceptible to resuspension by tidal currents than undisturbed bottom sediments. Natural sediment resuspension by wind waves and tidal current is less frequent or of smaller magnitude than anthropogenic sediment resuspension. The annual mass of sediment resuspended by vessel-generated long waves is estimated to be one order of magnitude greater than the annual mass of sediment resuspended by wind waves generated by winter storms.

  10. 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. PMID:19091379

  11. Estimating selenium removal by sedimentation from the Great Salt Lake, Utah

    USGS Publications Warehouse

    Oliver, W.; Fuller, C.; Naftz, D.L.; Johnson, W.P.; Diaz, X.

    2009-01-01

    The mass of Se deposited annually to sediment in the Great Salt Lake (GSL) was estimated to determine the significance of sedimentation as a permanent Se removal mechanism. Lake sediment cores were used to qualitatively delineate sedimentation regions (very high to very low), estimate mass accumulation rates (MARs) and determine sediment Se concentrations. Sedimentation regions were defined by comparison of isopach contours of Holocene sediment thicknesses to linear sedimentation rates determined via analysis of 210Pb, 226Ra, 7Be and 137Cs activity in 20 short cores (<5 cm), yielding quantifiable results in 13 cores. MARs were developed via analysis of the same radioisotopes in eight long cores (>10 cm). These MARs in the upper 1-2 cm of each long core ranged from 0.019 to 0.105 gsed/cm2/a. Surface sediment Se concentrations in the upper 1 or 2 cm of each long core ranged from 0.79 to 2.47 mg/kg. Representative MARs and Se concentrations were used to develop mean annual Se removal by sedimentation in the corresponding sedimentation region. The spatially integrated Se sedimentation rate was estimated to be 624 kg/a within a range of uncertainty between 285 and 960 kg/a. Comparison to annual Se loading and other potential removal processes suggests burial by sedimentation is not the primary removal process for Se from the GSL. ?? 2009 Elsevier Ltd.

  12. Concentrations and transport of suspended sediment, nutrients, and pesticides in the lower Mississippi-Atchafalaya River subbasin during the 2011 Mississippi River flood, April through July

    USGS Publications Warehouse

    Welch, Heather L.; Coupe, Richard H.; Aulenbach, Brent T.

    2014-01-01

    High streamflow associated with the April–July 2011 Mississippi River flood forced the simultaneous opening of the three major flood-control structures in the lower Mississippi-Atchafalaya River subbasin for the first time in history in order to manage the amount of water moving through the system. The U.S. Geological Survey (USGS) collected samples for analysis of field properties, suspended-sediment concentration, particle-size, total nitrogen, nitrate plus nitrite, total phosphorus, orthophosphate, and up to 136 pesticides at 11 water-quality stations and 2 flood-control structures in the lower Mississippi-Atchafalaya River subbasin from just above the confluence of the upper Mississippi and Ohio Rivers downstream from April through July 2011. Monthly fluxes of suspended sediment, suspended sand, total nitrogen, nitrate plus nitrite, total phosphorus, orthophosphate, atrazine, simazine, metolachlor, and acetochlor were estimated at 9 stations and 2 flood-control structures during the flood period. Although concentrations during the 2011 flood were within the range of what has been observed historically, concentrations decreased during peak streamflow on the lower Mississippi River. Prior to the 2011 flood, high concentrations of suspended sediment and nitrate were observed in March 2011 at stations downstream of the confluence of the upper Mississippi and Ohio Rivers, which probably resulted in a loss of available material for movement during the flood. In addition, the major contributor of streamflow to the lower Mississippi-Atchafalaya River subbasin during April and May was the Ohio River, whose water contained lower concentrations of suspended sediment, pesticides, and nutrients than water from the upper Mississippi River. Estimated fluxes for the 4-month flood period were still quite high and contributed approximately 50 percent of the estimated annual suspended sediment, nitrate, and total phosphorus fluxes in 2011; the largest fluxes were estimated at the water-quality station located at Vicksburg, Mississippi. The majority of the suspended-sediment flux introduce into the lower Mississippi-Atchafalaya River subbasin during the 2011 flood was in the form of fine-grained particles from the upper Mississippi River—77 percent of the suspended-sediment flux compared to 23 percent from the Ohio River. As water moved downstream along the lower Mississippi River, there were losses in suspended-sediment flux because of deposition and backwater areas. Fluxes showed a greater response to increased streamflow in the Atchafalaya River than in the lower Mississippi River. The result was a gain in suspended-sediment flux with distance downstream in the Atchafalaya River because of resuspension of previously deposited materials—particularly sand particles. Overall, 13 percent less suspended sediment left the lower Mississippi-Atchafalaya River subbasin than entered it from the confluence of the upper Mississippi and Ohio Rivers during the flood. The loss in suspended-sediment flux during the flood accounted for 14 percent of the 2011 annual suspended-sediment flux loss within the lower Mississippi-Atchafalaya River subbasin. Nitrate composed approximately 70 percent of the total nitrogen flux at all of the sampled water-quality stations, excluding the Arkansas River. Almost 2.4 times more nitrate flux entered the lower Mississippi-Atchafalaya River subbasin from the upper Mississippi River than from the Ohio River. As nitrate moved down the lower Mississippi River and the Atchafalaya River, there were no substantial losses or gains in flux, indicating that nitrate moved conservatively within the subbasin during the 2011 flood. Although streamflow was the largest on record, nitrate flux during the flood period resulted in a zone of hypoxia in the Gulf of Mexico that was only the tenth largest on record. The flux of total phosphorus in the lower Mississippi-Atchafalaya River subbasin during the 2011 flood was strongly related to suspended-sediment flux at most of the stations. There were significant gains in total phospho

  13. 78 FR 68023 - Annual Wholesale Trade Survey

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-13

    ...collect data covering annual sales, e- commerce sales, purchases, total operating...will collect data covering sales, e-commerce sales, year-end inventories held...collect data covering annual sales, e-commerce sales, year-end inventories...

  14. 76 FR 64894 - Annual Wholesale Trade Survey

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-19

    ...collect data covering annual sales, e-commerce sales, purchases, total operating...will collect data covering sales, e- commerce sales, year-end inventories held...collect data covering annual sales, e-commerce sales, year-end inventories...

  15. Cladoceran remains in lake sediments: a comparison between plankton counts and sediment records

    Microsoft Academic Search

    Mirva Nykänen; Kirsi Vakkilainen; Mikko Liukkonen; Timo Kairesalo

    2009-01-01

    To evaluate the comparability of neo- and paleo-limnology, we made year-to-year as well as seasonal comparisons of contemporary\\u000a zooplankton data and cladoceran remains in thick (9–42 mm) annual laminations in sediment of Lake Vesijärvi, southern Finland.\\u000a We calculated the expected annual exuviae production of nine planktonic taxa in the water column using contemporary zooplankton\\u000a records, and compared the value to the

  16. Predicting reservoir sedimentation

    E-print Network

    Wooten, Stephanie

    1997-01-01

    Sediments accumulate in reservoirs and significantly decrease storage capacity. Predicting sedimentation is an important consideration in the design of new reservoir projects and in the management of existing reservoirs. Sedimentation rates may vary...

  17. Identifying trends in sediment discharge from alterations in upstream land use

    USGS Publications Warehouse

    Parker, R.S.; Osterkamp, W.R.

    1995-01-01

    Environmental monitoring is a primary reason for collecting sediment data. One emphasis of this monitoring is identification of trends in suspended sediment discharge. A stochastic equation was used to generate time series of annual suspended sediment discharges using statistics from gaging stations with drainage areas between 1606 and 1 805 230 km2. Annual sediment discharge was increased linearly to yield a given increase at the end of a fixed period and trend statistics were computed for each simulation series using Kendal's tau (at 0.05 significance level). A parameter was calculated from two factors that control trend detection time: (a) the magnitude of change in sediment discharge, and (b) the natural variability of sediment discharge. In this analysis the detection of a trend at most stations is well over 100 years for a 20% increase in sediment discharge. Further research is needed to assess the sensitivity of detecting trends at sediment stations.

  18. Nutrient and suspended-sediment trends, loads, and yields and development of an indicator of streamwater quality at nontidal sites in the Chesapeake Bay watershed, 1985-2010

    USGS Publications Warehouse

    Langland, Michael; Blomquist, Joel; Moyer, Douglas; Hyer, Kenneth

    2012-01-01

    The U.S. Geological Survey (USGS) updates information on loads of, and trends in, nutrients and sediment annually to help the Chesapeake Bay Program (CBP) investigators assess progress toward improving water-quality conditions in the Chesapeake Bay and its watershed. CBP scientists and managers have worked since 1983 to improve water quality in the bay. In 2010, the U.S. Environmental Protection Agency (USEPA) established a Total Maximum Daily Load (TMDL) for the Chesapeake Bay. The TMDL specifies nutrient and sediment load allocations that need to be achieved in the watershed to improve dissolved oxygen, water-clarity, and chlorophyll conditions in the bay. The USEPA, USGS, and state and local jurisdictions in the watershed operate a CBP nontidal water-quality monitoring network and associated database that are used to update load and trend information to help assess progress toward reducing nutrient and sediment inputs to the bay. Data collected from the CBP nontidal network were used to estimate loads and trends for two time periods: a long-term period (1985-2010) at 31 "primary" sites (with storm sampling) and a 10-year period (2001-10) at 33 primary sites and 16 "secondary" sites (without storm sampling). In addition, loads at 64 primary sites were estimated for the period 2006 to 2010. Results indicate improving flow-adjusted trends for nitrogen and phosphorus for 1985 to 2010 at most of the sites in the network. For nitrogen, 21 of the 31 sites showed downward (improving) trends, whereas 2 sites showed upward (degrading) trends, and 8 sites showed no trends. The results for phosphorus were similar: 22 sites showed improving trends, 4 sites showed degrading trends, and 5 sites indicated no trends. For sediment, no trend was found at 40 percent of the sites, with 10 sites showing improving trends and 8 sites showing degrading trends. The USGS, working with CBP partners, developed a new water-quality indicator that combines the results of the 10-year trend analysis with results from a greater number of sites (64 primary sites) where loads and yields of total nitrogen and phosphorus and sediment could be calculated. The new indicator shows fewer significant trends for the 10-year time period than for the long-term time period (1985-2010). For 2001-10, total nitrogen trends were downward (improving) at 14 sites and upward (degrading) at 2 sites; no trend was found at 17 sites. For total phosphorus, 12 sites showed improving trends, 4 sites showed degrading trends, and 17 sites showed no trend. For total sediment, most sites (21) did not exhibit a significant trend; 3 sites showed improving trends, and 10 sites showed degrading trends. Few significant trends were seen at the 16 secondary sites: improving trends for total nitrogen at 4 sites, improving trends for total phosphorus at 2 sites, and a degrading trend for sediment at 1 site. Total streamflow to the Chesapeake Bay was 20 percent higher in 2010 than in 2009 and is considered to be within the normal range of flow, whereas annual streamflow at 28 sites was greater in 2010 than in 2009. No trends in daily streamflow were detected at the 31 long-term sites. Combined loads for the farthest downstream nontidal monitoring sites (called "River Input Monitoring sites") increased 33 percent for total nitrogen, 120 percent for total phosphorus, and 330 percent for total sediment from 2009 to 2010. The large increase in phosphorus and sediment loads in 2010 was caused in large part by two large storm events that occurred during the spring in the Potomac River Basin. Yields (load per watershed area) of total nitrogen in the Chesapeake Bay watershed decreased from north to south (New York to Virginia). No spatial patterns were discernible for total phosphorus or sediment.

  19. Surface sediment analysis and modern sedimentation rates in Flandres Bay, Western Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Munoz, Y. P.; Wellner, J. S.; Mead, K. A.

    2012-12-01

    Flandres Bay is located on the west side of the Antarctic Peninsula, where temperatures have risen more than the global average over the last century and where many glaciers have shown signs of retreat in recent decades. The Antarctic Ice Cap drains through tidewater glaciers that flow into bays around the peninsula. In this study, multibeam swath bathymetry data, seismic profiles, and sediment cores were used to determine the distribution of surface sediment types and modern sedimentation rates and compare these to the sediment accumulation down core. The bathymetry of the fjord includes small basins with flat bottoms, highly irregular seamounts, and deep channels in the bedrock as well as subglacial geomorphic features carved by the flow of glaciers. Results of sediment analysis show a variation in sediment type throughout the bay from pebbles with minor matrix close to the glacial calving margin to muddy diatomaceous ooze in the outer bay. Sediment accumulation rates were measured using 137 Cs counts on bulk sediment and 14 C on carbonate, usually forams, found after sieving bulk sediment. Samples for 137 Cs were taken on the top few centimeters of sediment cores and show a higher rate of sediment accumulation compared to rates calculated using 14 C, which measures millennial scale accumulation rates to the base of the core. Density logs of the sediment cores have relatively consistent values, indicating that the change in calculated accumulation rates is not simply due to compaction. As predicted, accumulation rates are higher close to the glaciers, where there is a high occurrence of ice rafted debris and dropstones; the sedimentation rates decrease away from the source and sediment analysis shows an increase in the biogenic component in the sediment, especially diatoms, in the outer bay. Other fjords adjacent to Flandres Bay, including Beascochea to the south, show similar trends of increasing rates of sediment accumulation in the upper portions of cores. In a simple model, sediment accumulation rate at any one location would decrease as the ice margin retreats, leaving the sample location more and more distal from the sediment source. However, as our results show increasing sediment accumulation during modern day ice-margin retreat in Flandres Bay, we interpret this to indicate increased sediment yield across the basin with ice is in a retreat phase, possibly undergoing faster flow, yielding a greater total volume of sediment.

  20. A spatially referenced regression model (SPARROW) for suspended sediment in streams of the Conterminous U.S.

    USGS Publications Warehouse

    Schwarz, Gregory E.; Smith, Richard A.; Alexander, Richard B.; Gray, John R.

    2001-01-01

    Suspended sediment has long been recognized as an important contaminant affecting water resources. Besides its direct role in determining water clarity, bridge scour and reservoir storage, sediment serves as a vehicle for the transport of many binding contaminants, including nutrients, trace metals, semi-volatile organic compounds, a nd numerous pesticides (U.S. Environmental Protection Agency, 2000a). Recent efforts to addr ess water-quality concerns through the Total Maximum Daily Load (TMDL) process have iden tified sediment as the single most prevalent cause of impairment in the Nation’s streams a nd rivers (U.S. Environmental Protection Agency, 2000b). Moreover, sediment has been identified as a medium for the tran sport and sequestration of organic carbon, playing a potentia lly important role in understa nding sources and sinks in the global carbon budget (Stallard, 1998). A comprehensive understanding of sediment fate a nd transport is considered essential to the design and implementation of effective plans for sediment management (Osterkamp and others, 1998, U.S. General Accounting Office, 1990). An exte nsive literature addr essing the problem of quantifying sediment transport has produced a nu mber of methods for estimating its flux (see Cohn, 1995, and Robertson and Roerish, 1999, for us eful surveys). The accuracy of these methods is compromised by uncertainty in the concentration measurements and by the highly episodic nature of sediment movement, particul arly when the methods are applied to smaller basins. However, for annual or decadal flux es timates, the methods are generally reliable if calibrated with extended periods of data (Robertson and Roerish, 1999). A substantial literature also supports the Universal Soil Loss Equation (U SLE) (Soil Conservation Service, 1983), an engineering method for estimating sheet and rill erosion, although the empirical credentials of the USLE have recently been questioned (Tri mble and Crosson, 2000). Conversely, relatively little direct evidence is available concerning the fate of sediment. The common practice of quantifying sediment fate with a sediment deliv ery ratio, estimated from a simple empirical relation with upstream basin area, does not artic ulate the relative importance of individual storage sites within a basin (Wolman, 1977). Rates of sediment deposition in reservoirs and flood plains can be determined from empirical measurement s , but only a limited number of sites have been monitored, and net rates of deposition or loss from other potential sinks and sources is largely unknown (Stallard, 1998). In particular, little is known about how much sediment loss from fields ultimately makes its way to stream channels, and how much sediment is subsequently stored in or lost from th e streambed (Meade and Parker, 1985, Trimble and Crosson, 2000). This paper reports on recent progress made to a ddress empirically the question of sediment fate and transport on a national scale. The model pres ented here is based on the SPAtially Referenced Regression On Watershed attr ibutes (SPARROW) methodology, fi rst used to estimate the distribution of nutrients in str eams and rivers of the United Stat es, and subsequently shown to describe land and stream processes affecting the delivery of nutrients (Smith and others, 1997, Alexander and others, 2000, Preston and Brakeb ill, 1999). The model makes use of numerous spatial datasets, available at the national level, to explain long-term sediment water-quality conditions in major streams and rivers throughou t the United States. Sediment sources are identified using sediment erosion rates from the National Resources I nventory (NRI) (Natural Resources Conservation Service, 2000) and apportioned over the landscape according to 30- meter resolution land-use information from th e National Land Cover Data set (NLCD) (U.S. Geological Survey, 2000a). More than 76,000 reservoirs from the National Inventory of Dams (NID) (U.S. Army Corps of Engin eers, 1996) are identified as pot ential sediment sinks. Other, non-anthropogenic sou

  1. 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. PMID:25012206

  2. Distinguishing human and climate influences on the Columbia River: Changes in mean flow and sediment transport

    NASA Astrophysics Data System (ADS)

    Naik, Pradeep K.; Jay, David A.

    2011-07-01

    SummaryMost hydrologic trends result from a combination of climatic and human influences, and analyses of hydrologic changes often do not differentiate these factors, despite the obvious relevance of this distinction. Here, we separate human and climate influences on the Columbia River hydrologic cycle and sediment discharge on the basis of robust data analyses since 1858. Human influences include water withdrawal for irrigation, flow regulation, reservoir manipulation, mining and deforestation. The Columbia's streamflow and sediment discharge are strongly correlated with large-scale climate patterns, particularly the ENSO (El Niño Southern Oscillation) and PDO (Pacific Decadal Oscillation). The mean annual Columbia River virgin flow at The Dalles has decreased ˜16.5%, 8-9% due to climate change and 7-8% due to water withdrawal for irrigation. Climate impacts on the sediment discharge are larger than on streamflow because sediment discharge increases more than linearly with flow. Total sediment and sand transports have decreased >50% and >70% respectively, only a fraction of which is due to climate change. Changes in the timing of maximum flows from sub-basins, as influenced by flow regulation and irrigation withdrawal, determine freshet timing and play a larger role in determining the maximum flow and sediment transport levels. Flow regulation (since 1970) has decreased peak spring flows by ˜45% and increased flow during the rest of the year. The spring freshet flow decrease due to climate change is 11%; the decreases due to water withdrawal and flow regulation are about 12% and 26% respectively. The peak freshet flow now typically occurs 2-4 weeks earlier than before 1900.

  3. Spatial Variations in Archaeal Lipids of Surface Water and Core-Top Sediments in the South China Sea and Their Implications for Paleoclimate Studies?†

    PubMed Central

    Wei, Yuli; Wang, Jinxiang; Liu, Jie; Dong, Liang; Li, Li; Wang, Hui; Wang, Peng; Zhao, Meixun; Zhang, Chuanlun L.

    2011-01-01

    The South China Sea (SCS) is the largest marginal sea of the western Pacific Ocean, yet little is known about archaeal distributions and TEX86-based temperatures in this unique oceanic setting. Here we report findings of abundances in both core lipids (CL) and intact polar lipids (IPL) of Archaea from surface water (CL only) and core-top sediments from different regions of the SCS. TEX86-derived temperatures were also calculated for these samples. The surface water had extremely low abundances of CL (average of 0.05 ± 0.13 ng/liter; n = 75), with higher values present in regions where upwelling is known to occur. The core-top sediments had CL values of 0.1 to 0.9 ?g/g, which are on the low end of CL concentrations reported for other marine sediments and may reflect the oligotrophic nature of the open SCS. The IPL of Archaea accounted for 6 to 36.4% of total lipids (CL plus IPL), indicating that the majority of archaeal lipids in core-top sediments were derived from nonliving cells. The TEX86-based temperatures of surface water were overall lower than satellite-based sea surface temperatures or CTD-measured in situ temperatures. The core-top sediment samples, however, had TEX86 temperatures very close to the mean annual sea surface temperatures, except for samples with water depths of less than 100 m. Our results demonstrated low and heterogeneous distributions of archaeal lipids in surface water and core-top sediments of the SCS, which may reflect local or regional differences in productivity of Archaea. While TEX86-based temperatures for core-top marine sediments at deep water depths (>100 m) generally reflected mean annual sea surface temperatures, TEX86 temperatures in surface water varied basin wide and underestimated sea surface temperatures in most locations for the season when surface water samples were collected. PMID:21890672

  4. Mercury in Green Bay, Lake Michigan Surficial Sediments Collected between 1987 and 1990

    Microsoft Academic Search

    Ronald Rossmann; David N. Edgington

    2000-01-01

    Sediments were collected by gravity core from 74 locations in Green Bay, Lake Michigan. Surficial sediments (0 to 1 cm depth) from these stations were analyzed for total mercury for the purpose of describing the horizontal variation of mercury in Green Bay sediments, estimating mercury fluxes to surficial sediments, and identifying potential sources of mercury. With concentrations ranging between 0.006

  5. Dissolved and particulate carbohydrates in contrasting marine sediments

    NASA Astrophysics Data System (ADS)

    Burdige, D. J.; Skoog, A.; Gardner, K.

    2000-03-01

    Dissolved and particulate carbohydrates were examined in contrasting Chesapeake Bay (estuarine) and mid-Atlantic shelf/slope break (continental margin) sediments. Particulate carbohydrates (PCHOs) represented ˜5-9% of the total sediment particulate organic carbon (POC), and PCHO remineralization appeared to be a similar fraction of total sediment carbon oxidation (or C ox). When these results are compared with results from other coastal sediments and a pelagic turbidite, PCHO remineralization (as a percentage of C ox) did not vary by more than a factor of ˜2-3 over a 3-4 order of magnitude range in C ox values. The causes of this are not well understood, but may be related to specific effects associated with the remineralization of highly altered organic matter mixtures under aerobic conditions. Dissolved carbohydrates (DCHOs) in these sediment pore waters ranged from ˜30 to 400 ?M, increased with depth in a manner similar to total DOC, and represented ˜10 to 55% of pore water DOC. In Chesapeake Bay sediments this percentage decreased with sediment depth, while in these continental margin sediments it was constant (upper 30 cm). Of the DCHOs in these pore waters ˜30 to 50% could be identified as individual aldoses (monomeric neutral sugars), and total aldose yields (individual aldoses as a percentage of total DOC) were higher in these continental margin sediment pore waters (>9%) than they were in the estuarine sediment pore waters (<5%). A comparison of DCHO and PCHO concentrations in these sediments indicates that their concentrations are uncoupled, and that pore water DCHO concentrations are primarily controlled by sediment remineralization processes. Pore water DCHOs appeared to be preferentially found in the high molecular weight (HMW) DOC pool, and likely occur as some of the initial HMW intermediates produced and consumed during sediment POC remineralization. These results also support past suggestions about the differing controls on carbon remineralization processes in continental margin versus estuarine sediments.

  6. Climate, Ice, and Mud: investigating the relationship between glacier activity and sediment flux using varved lake sediments, Iceland

    NASA Astrophysics Data System (ADS)

    Larsen, D. J.; Miller, G. H.; Geirsdottir, A.; Flowers, G. E.; Bjornsson, H.

    2012-12-01

    The worldwide retreat of many glaciers during the 21st century is expected to have profound impacts on local and regional hydrologic cycles. Associated with the forecasted reductions in global ice volume are changes in meltwater runoff and sediment transport in glacially fed drainage systems. Alpine glaciers and small ice caps are particularly sensitive to climate change because their dimensions can respond quickly to changes in glacier mass balance. Records of past glacier fluctuations are important sources of paleoclimate data and also provide a context for current and future changes to glacier hydrologic systems. Annually laminated (varved) sediments from proglacial lake Hvítárvatn, central Iceland, offer a continuous archive of Langjökull ice cap (~925 km2) activity through the late Holocene. A multi-proxy record from this site indicates that Langjökull's size was more variable during the past millennium than during any other multi-centennial interval of the Holocene. Ice growth culminated in the Little Ice Age (LIA), when Langjökull advanced into Hvítárvatn and reached its maximum aerial extent of the past 10 ka. At present, roughly one-third of the ice cap's discharge flows into the lake catchment, constituting ~70% of the total inflow, and lake sedimentation rates are governed by the production and delivery of glacially eroded clastic material transported to the lake by four primary meltwater streams. Glacier fluctuations of the past 1 ka are reconstructed from physical proxies contained in sediment cores retrieved from six locations throughout the main basin. Total sediment yield and distribution during this period are calculated from sediment accumulation rates and from > 100 km of seismic reflection profiles. A tephra-constrained varve chronology provides high chronologic control, with a maximum age uncertainty of ± 10 years. Low and constant sedimentation rates characterize the 11th and 12th centuries, reflecting minimal glacier activity during medieval times. The onset of LIA cooling is marked by the first of two major advances of Langjökull, which began ~1275 AD and increased in magnitude around 1400 AD. The start of the second major glacier advance occurred at ~1700 AD, with Langjökull reaching the lakeshore by 1760 AD and achieving its maximum extent between 1840 and 1890 AD. The empirical record of Langjökull's activity during the past millennium is compared to a time series of model simulated ice cap area to evaluate spatial patterns in ice growth/retreat, temporal changes in sediment yield, and the relative contribution of glacially eroded sediment from different sectors of the ice cap within the lake catchment. The evolution of modeled ice cap extent, which is driven by the NGRIP ?18O record, shows remarkable similarity to changes in varve thickness over the past millenium. This comparison suggests it may be possible to quantify the relationship between changes in glacier size and corresponding changes in the fluvial transport of ice erosional products.

  7. 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

  8. Geochemistry of Peruvian near-surface sediments

    NASA Astrophysics Data System (ADS)

    Böning, Philipp; Brumsack, Hans-Jürgen; Böttcher, Michael E.; Schnetger, Bernhard; Kriete, Cornelia; Kallmeyer, Jens; Borchers, Sven Lars

    2004-11-01

    Sixteen short sediment cores were recovered from the upper edge (UEO), within (WO) and below (BO) the oxygen minimum zone (OMZ) off Peru during cruise 147 of R/V Sonne. Solids were analyzed for major/trace elements, total organic carbon, total inorganic carbon, total sulfur, the stable sulfur isotope composition (? 34S) of pyrite, and sulfate reduction rates (SRR). Pore waters were analyzed for dissolved sulfate/sulfide and ? 34S of sulfate. In all cores highest SRR were observed in the top 5 cm where pore water sulfate concentrations varied little due to resupply of sulfate by sulfide oxidation and/or diffusion of sulfate from bottom water. ? 34S of dissolved sulfate showed only minor downcore increases. Strong 32S enrichments in sedimentary pyrite (to -48‰ vs. V-CDT) are due to processes in the oxidative part of the sulfur cycle in addition to sulfate reduction. Manganese and Co are significantly depleted in Peruvian upwelling sediments most likely due to mobilization from particles settling through the OMZ, whereas release of both elements from reducing sediments only seems to occur in near-coastal sites. Cadmium, Mo and Re are exceptionally enriched in WO sediments (<600 m water depth). High Re and moderate Cd and Mo enrichments are seen in BO sediments (>600 m water depth). Re/Mo ratios indicate anoxic and suboxic conditions for WO and BO sediments, respectively. Cadmium and Mo downcore profiles suggest considerable contribution to UEO/WO sediments by a biodetrital phase, whereas Re presumably accumulates via diffusion across the sediment-water interface to precipitation depth. Uranium is distinctly enriched in WO sediments (due to sulfidic conditions) and in some BO sediments (due to phosphorites). Silver transfer to suboxic BO sediments is likely governed by diatomaceous matter input, whereas in anoxic WO sediments Ag is presumably trapped due to sulfide precipitation. Cadmium, Cu, Zn, Ni, Cr, Ag, and T1 predominantly accumulate via biogenic pre-concentration in plankton remains. Rhenium, Sb, As, V, U and Mo are enriched in accordance with seawater TE availability. Lead and Bi enrichment in UEO surface sediments is likely contributed by anthropogenic activity (mining). Accumulation rates of TOC, Cd, Mo, U, and V from Peruvian and Namibian sediments exceed those from the Oman Margin and Gulf of California due to enhanced preservation off Peru and Namibia.

  9. Sediment quality in Rivers and their estuaries of an olive oil production area, Messinia, Greece.

    NASA Astrophysics Data System (ADS)

    Anastasopoulou, Evaggelia; Pavlidou, Alexandra; Skoulikidis, Nikos; Dassenakis, Manos; Hatzianestis, Ioannis

    2014-05-01

    Sediment analysis at four major rivers (Pamisos, Aris, Velikas and Nedon) and their estuaries towards heavy metals took place in the Prefecture of Messinia, Greece, during two sampling campaigns in 2008 and 2011. The main industrial activity in the region is the operation of 250 olive oil industries and the main problem concerning pollution derives from the vast quantities of olive mill waste waters that are being generated annually most of which is currently discharged in nearby streams. Chemical parameters such as phenols, total organic carbon and certain heavy metals were found to be strongly correlated with the wastes from the olive oil industries. Major and minor elements (heavy metals) were measured in riverine and estuarine sediments. In parallel heavy metals were determined in the olive waste from a local industry, using atomic absorption spectrometry, in order to correlate the results with the sediment analysis. Major and Minor elements were recorded based upon the total percentage of the sediment samples and in order to eliminate the grain size effect, the concentrations were normalized towards Al. A pollution indice, the sediment enrichment factor, was also calculated, the high values of which towards Cr are of particular interest. Additionally organic carbon and total phenolic compounds were determined in rivers and their estuaries. High concentrations of Chromium were recorded in River Aris sediment, which seems to be the most polluted. Relatively high concentrations of zinc were encountered at rivers Aris and Pamisos while the chromium load seems to be higher near the estuaries of the rivers. The olive mill waste water analysis confirmed the existence of chromium in the waste and extremely elevated values were also found at a nearby station where these wastes tend to accumulate for decades. In contrast the results from the Nedon River indicated that it is not affected, since the low values found remained constant from the source of the river until its outfall in the Messinian Gulf. A significant enrichment in phenolic content of sediments as well in organic carbon was observed in 2011 when compared to 2008, in most of the cases, indicating degradation of the study aquatic ecosystems of Messinia Prefecture.

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

    PubMed

    Bogen, J; Bønsnes, T E

    2001-02-01

    When the Svartisen hydroelectric power plant was put into operation, extensive sediment pollution was observed in the downstream fjord area. This paper discusses the impact of the power plant and the contribution from various sources of sediment. Computation of the sediment load was based on samples collected one to four times per day. Grain size distribution analyses of suspended sediments were carried out and used as input in a routing model to study the movement of sediments through the system. Suspended sediment delivered to the fjord before the power station was constructed was measured as 8360 metric tons as an annual mean for a 12-year period. During the years 1995-1996 when the power plant was operating, the total suspended load through the power station was measured as 32609 and 30254 metric tons, respectively. Grain size distribution analyses indicate a major change in the composition of the sediments from 9% clay before the power plant was operative to 50-60% clay afterwards. This change, together with the increase in sediment load, is believed to be one of the main causes of the drastic reduction in secchi depths in the fjord. The effect of the suspended sediment load on the fjord water turbidity was evaluated by co-plotting secchi depth and power station water discharge. Measurements during 1995 and 1996 showed that at the innermost of these locations the water failed to attain the minimum requirement of 2 m secchi depth. In later years secchi depths were above the specified level. In 1997 and 1998 the conditions improved. At the more distal locality, the conditions were acceptable with only a few exceptions. A routing model was applied to data acquired at a location 2 km from the power station in order to calculate the contributions from various sediment sources. This model indicated that the contribution from reservoir bed erosion dominated in 1994 but decreased significantly in 1995. Future operation of the power station will mostly take place with a high water level in the reservoir and is likely to result in acceptable water quality in the fjord. However, during periods of low drawdown, sediment pollution may again become a problem. PMID:11258827

  11. Sediment and Particular Organic Carbon (POC) fluxes changes over the past decades in the Yellow River system

    NASA Astrophysics Data System (ADS)

    Lu, Xixi; Ran, Lishan

    2015-04-01

    The Yellow River system used to have very high sediment export to ocean (around 1.5 Gt/yr in the 1950s) because of severe soil erosion on the Loess Plateau. However, its sediment export has declined to <0.25 Gt/yr in recent years (in the 2000s), mainly due to human activities like construction of reservoirs and check dams and other soil and water conservations such as construction of terraces and vegetation restoration. Such drastic reduction in soil erosion and sediment flux and subsequently in associated Particular Organic Carbon (POC) transport can potentially play a significant role in carbon cycling. Through the sediment flux budget we examined POC budget and carbon sequestration through vegetation restoration and various soil and water conservations including reservoirs construction over the past decades in the Yellow River system. Landsat imageries were used to delineate the reservoirs and check dams for estimating the sediment trapping. The reservoirs and check dams trapped a total amount of sediment 0.94 Gt/yr, equivalent to 6.5 Mt C. Soil erosion controls through vegetation restoration and terrace construction reduced soil erosion 1.82 Gt/yr, equivalent to 12 Mt C. The annual NPP increased from 0.150 Gt C in 2000 to 0.1889 Gt C in 2010 with an average increment rate of 3.4 Mt C per year over the recent decade (from 2000 to 2010) through vegetation restoration. The total carbon stabilized on slope systems through soil erosion controls (12 Mt C per year) was much higher than the direct carbon sequestration via vegetation restoration (3.4 Mt C per year), indicating the importance of horizontal carbon mobilization in carbon cycling, albeit a high estimate uncertainty.

  12. Sediment dynamics in the Mekong basin- a multi-objective calibration on discharge and sediment load

    NASA Astrophysics Data System (ADS)

    Luedtke, Stefan; Apel, Heiko; Viet Dung, Nguyen; Merz, Bruno

    2013-04-01

    The Mekong delta is one of the most extensively used deltas world wide and provides natural resources to more than 17 million people. Environmental issues in the Mekong delta are closely linked to water usage and availability. In addition, the sediment input to the floodplains during the annual flood plays a crucial role in terms of nutrient supply to agriculture. Since flood magnitudes and sediment delivery are driven by human activities and hydrological processes along the entire Mekong river, it is highly important to assess the dynamics upstream of the Mekong delta. This study applies the hydrological model SWIM to the watershed upstream of Kratie/Cambodia with a size of approximately 650.000 km2 and gives a quantitative depiction on the sediment and discharge dynamics. The model is driven by different, mostly globally available data sources. After the identification of the sensitive parameters, a multi objective calibration, namely the NSGA-II algorithm, is applied. The model simulates the discharge values well, e.g. by capturing the annual flood season and sediment dynamics. The next steps comprise an assessment of different sources of uncertainty that are incorporated in the model. This includes the climate input data and the sparsely available and highly variable sediment data. Eventually, the study shall provide a basis to examine the future developments along the Mekong river, for example, quantifying the impacts of potential reservoirs on the flow regime and sediment dynamics.

  13. Notes on sedimentation activities calendar year 1987

    USGS Publications Warehouse

    U.S. Interagency Advisory Committee on Water Data- Subcommittee on Sedimentation

    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.

  14. Notes on sedimentation activities calendar year 1989

    USGS Publications Warehouse

    U.S. Interagency Advisory Committee on Water Data- Subcommittee on Sedimentation

    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.

  15. Notes on sedimentation activities calendar year 1984

    USGS Publications Warehouse

    U.S. Interagency Advisory Committee on Water Data- Subcommittee on Sedimentation

    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.

  16. Notes on sedimentation activities calendar year 1985

    USGS Publications Warehouse

    U.S. Interagency Advisory Committee on Water Data- Subcommittee on Sedimentation

    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.

  17. Notes on sedimentation activities calendar year 1988

    USGS Publications Warehouse

    U.S. Interagency Advisory Committee on Water Data- Subcommittee on Sedimentation

    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.

  18. Effect of an aquatic herbicide on sediment nutrient flux in a freshwater marsh

    Microsoft Academic Search

    L. G. Goldsborough; G. G. C. Robinson

    1985-01-01

    Three concentrations of the herbicide simazine were added to in situ macrophyte-free enclosures with and without sediment contact. Changes in the concentrations of total ammonia, total reactive phosphorus, and silicon were monitored, and net sediment flux was calculated from the difference in nutrient concentration between bottomed and unbottomed enclosures. Rates of sediment release for all three nutrients were unaltered by

  19. Scale as a factor in designing sampling programs for determination of annual trace element fluxes

    USGS Publications Warehouse

    Horowitz, A.J.

    1995-01-01

    Concentration data of suspended sediment-associated trace elements are a requisite for estimation of annual chemical fluxes. Fluvial suspended sediment and associated trace elements display marked shortterm spatial and temporal variability, suggesting that determination of annual fluxes requires high frequency depth and width integrated sampling and subsequent chemical analyses. When time scales are shifted from hours or days to a year, short-term variability is less important. A 2 year study on the Arkansas River indicates that it may be possible, after detailed site characterization of mean/median sediment chemical data, to estimate annual fluxes of trace elements solely through monitoring of discharge and suspended sediment concentration.

  20. Controls and budgets of riverine sediment fluxes to the Gulf of Lions (NW Mediterranean Sea) : Do coastal rivers better than the Rhone?

    NASA Astrophysics Data System (ADS)

    Sadaoui, Mahrez; Ludwig, Wolfgang; Bourrin, François; Raimbault, Patrick

    2015-04-01

    Riverine sediment yields can be highly variable among the various river systems on Earth and, despite an increasing amount of data and studies during recent years. Small rivers can be more efficient in the evacuation of freshly eroded materials, attributing greater sediment delivery ratios to these rivers compared to large river systems. The Gulf of Lions (GoL), north-western Mediterranean Sea, is one of the most extensive shelf regions in the Mediterranean Sea. Riverine sediment fluxes from small coastal rivers (SCR) along the Languedoc-Roussillon coast can be compared to the fluxes of the Rhone River, one of the largest in the Mediterranean. Since the late 1990, however, several research programs got interested in these river systems and individual rivers were studied more in detail. Long-term monitoring of the Tet and Rhone rivers was established and finally integrated in the French oceanographic observation system MOOSE (Mediterranean Ocean Observing system of the Environment). In this context, the present study aims to complete the existing studies by providing a reliable comparison of sediment load values for various catchments within lowland river basins. Therefore, we focused on the SCR and Rhone river basins, 7 catchments covering 86 % of this area. We first present a large database of area-specific suspended sediment yields (SSY) calculated from the suspended sediment concentration and flow discharge data over 46 years of measurements at gauging stations. A Simple Rating Curve Approach (SiRCA) using daily discharge data, which allows the estimation of mean annual sediment loads from infrequent sediment concentration data, was used to calculate sediment fluxes. Second, we analyze the temporal and spatial variability of the calculated of sediment load (SL) values, and the contribution of floods in the annual report of sediment yield. Finally, we estimate the contribution of the coastal rivers in total inputs in the GoL. The SL values at the outlet of the catchments range from 0.045 Mt.yr-1 to 8.37 Mt.yr-1, and the SSY values range from 19 to 87 t.km-2.yr-1. A comparison with the limited values available in the literature for this region corroborates our estimations. The most of sediments are exported during episodes of flooding, more of 50% of sediment exported during flash floods events which occur only 1.5 of time. The watershed area of all SCR presents 13.03 % face to Rhone. The inputs of SCR present 9.19 % compared to those of the Rhone over the period studied (46 years). Seasonally, the contribution of the SCR is especially important during late spring and autumn, when flash-floods can occur. Under these conditions, they can even contribute to >90% of the total monthly sediment discharge. Keywords: Gulf of Lion, SiRCA method, small coastal rivers, Rhone river, sediment load, specific sediment yields.

  1. Sources and transport of sediment, nutrients, and oxygen-demanding substances in the Minnesota River basin, 1989-92

    USGS Publications Warehouse

    Payne, G.A.

    1994-01-01

    The Minnesota River, 10 major tributaries, and 21 springs were sampled to determine the sources and transport of sediment, nutrients, and oxygen- demanding substances. The study was part of a four-year assessment of non-point source pollution in the Minnesota River Basin. Runoff from tributary watersheds was identified as the primary source of suspended sediment and nutrients in the Minnesota River mainstem. Suspended-sediment, phosphorus, and nitrate concentrations were elevated in all major tributaries during runoff, but tributaries in the south-central and eastern part of the basin produce the highest annual loading to the mainstem because of higher annual precipitation and runoff in that part of the basin. Particle-size analyses showed that most of the suspended sediment in transport consisted of silt- and clay-size material. Phosphorus enrichment was indicated throughout the mainstem by total phosphorus concentrations that ranged from 0.04 to 0.48 mg/L with a median value of 0.22 mg/L, and an interquartile range of 0.15 to 0.29 mg/L. Nitrate concentrations periodically exceeded drinking water standards in tributaries draining the south-central and eastern part of the basin. Oxygen demand was most elevated during periods of summer low flow. Correlations between levels of biochemical oxygen demand and levels of algal productivity suggest that algal biomass comprises much of the oxygen-demanding material in the mainstem. Transport of sediment, nutrients, and organic carbon within the mainstem was found to be conservative, with nearly all tributary inputs being transported downstream. Uptake and utilization of nitrate and orthophosphorus was indicated during low flow, but at normal and high flow, inputs of these constituents greatly exceeded biological utilization.

  2. 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 and taken account for. The study showed that common fingerprint elements and practices would have led to misinterpretations in the Wadi Al-Arab catchment and calls for a sound knowledge on catchment characteristics before the implementation of such a method.

  3. 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 erosion and progression of the delta front in Lake Mills, and the upcoming release of the coarse sediment from Lake Mills once the delta reaches the dam. The first wave of coarse bedload sediment is expected to be released in late fall of 2012.NPS web camera photograph of the Lake Mills delta upstream from Glines Canyon Dam.

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

    USGS Publications Warehouse

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

    2009-01-01

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

  5. Aliphatic hydrocarbons in sediments of Lake Washington

    Microsoft Academic Search

    STUART G. WAKEHAM; ROY CARPENTER

    1976-01-01

    Abslract The distribution of aliphatic hydrocarbons in sediments from several locations in Lake Washington have been determined by gas chromatographic, radiocarbon, and stable carbon isotope analysts. Most surface sediments contain an average of about 1,400 ,ug g-l dry wt total nliphatic hydrocarbons, of which about 10 mg g1 are n-paraffins. Gas chromatograms of these hydrocarbons and radiocarbon ages of about

  6. Tracing the origin of suspended sediment in a large Mediterranean river by combining continuous river monitoring and measurement of artificial and natural radionuclides.

    PubMed

    Zebracki, Mathilde; Eyrolle-Boyer, Frédérique; Evrard, Olivier; Claval, David; Mourier, Brice; Gairoard, Stéphanie; Cagnat, Xavier; Antonelli, Christelle

    2015-01-01

    Delivery of suspended sediment from large rivers to marine environments has important environmental impacts on coastal zones. In France, the Rhone River (catchment area of 98,000 km(2)) is by far the main supplier of sediment to the Mediterranean Sea and its annual solid discharge is largely controlled by flood events. This study investigates the relevance of alternative and original fingerprinting techniques based on the relative abundances of a series of radionuclides measured routinely at the Rhone River outlet to quantify the relative contribution of sediment supplied by the main tributaries during floods. Floods were classified according to the relative contribution of the main subcatchments (i.e., Oceanic, Cevenol, extensive Mediterranean and generalised). Between 2000 and 2012, 221 samples of suspended sediment were collected at the outlet and were shown to be representative of all flood types that occurred during the last decade. Three geogenic radionuclides (i.e., (238)U, (232)Th and (40)K) were used as fingerprints in a multivariate mixing model in order to estimate the relative contribution of the main subcatchment sources-characterised by different lithologies-in sediment samples collected at the outlet. Results showed that total sediment supply originating from Pre-Alpine, Upstream, and Cevenol sources amounted to 10, 7 and 2.10(6)tons, respectively. These results highlight the role of Pre-Alpine tributaries as the main sediment supplier (53%) to the Rhone River during floods. Other fingerprinting approaches based on artificial radionuclide activity ratios (i.e., (137)Cs/(239+240)Pu and (238)Pu/(239+240)Pu) were tested and provided a way to quantify sediment remobilisation or the relative contributions of the southern tributaries. In the future, fingerprinting methods based on natural radionuclides should be further applied to catchments with heterogeneous lithologies. Methods based on artificial radionuclides should be further applied to catchments characterised by heterogeneous post-Chernobyl (137)Cs deposition or by specific releases of radioactive effluents. PMID:25255199

  7. Rejuvenating Poldered Landscapes in a Tidally-Dominated, Sediment-Rich Delta: A Numerical Model and Analysis of the Effectiveness of Tidal River Management in Coastal Bangladesh

    NASA Astrophysics Data System (ADS)

    Tasich, C. M.; Goodbred, S. L., Jr.; Gilligan, J. M.; Wilson, C.

    2014-12-01

    The low-lying, coastal region of Bangladesh has relied on poldering (the creation of embanked islands) since the 1960s to mitigate the effects of tidal inundation and storm surge from tropical cyclones. The result has been an increase in total arable land and the ability to sustain food production for one of the most densely populated countries in the world. However, poldering has had the unintended consequences of starving embanked landscapes of sediment and increasing high water levels through tidal amplification. Thus, polder elevations have been declining while tidal channels have been aggrading. Recent small-scale engineering projects, locally referred to as tidal river management (TRM), have attempted to combat these effects by allowing water and sediment exchange between the polders and the tidal network. Anecdotal reports claim great success for TRM in some locations, but not in others. However, to date there has been almost no quantitative analysis. Here, we used measured sedimentation rates and water level data from Polder 32 (P32) and the adjacent pristine mangrove forest in southwest Bangladesh to parameterize a simple model of tidal inundation and resultant sediment accretion. P32 elevations are currently ~1 m lower than natural elevations resulting in ~105 cm of tidal inundation when embankments were breached versus only ~20 cm for the mangrove forest. We measured sedimentation rates of 20 cm/yr and 1 cm/yr, respectively. When normalized to the cumulative annual flooding depth, the resulting sediment extraction rates yield similar values of 300 mg/L and 230 mg/L. We employ these flooding depth and sediment extraction parameters in our model to quantify the amount of time and sediment needed to re-equilibrate the lowered polder elevation to that of the natural environment. Although relatively simple, results from this preliminary model corroborate anecdotes of TRM's effectiveness at restoring land-surface elevations in the polders of Bangladesh. Future work will add spatial variation and possibly integrate human actions with agent-based models.

  8. Diversity and distribution of bacterial communities in dioxin-contaminated sediments from the Houston ship channel 

    E-print Network

    Hieke, Anne-Sophie Charlotte

    2009-05-15

    the presence or absence of Dehalococcoides in HSC sediments. Molecular methods including PCR, cloning, restriction enzyme digest, and sequencing were used to determine the diversity of Dehalococcoides as well as total bacterial diversity in HSC sediments...

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

    NASA Astrophysics Data System (ADS)

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

    1995-06-01

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

  10. Modeling the Effects of Climate Change on Water, Sediment, and Nutrient Discharge from the Maumee River Watershed

    NASA Astrophysics Data System (ADS)

    Cousino, L. K.; Becker, R.; Zmijewski, K. A.

    2013-12-01

    A hydrologic model of the Maumee River watershed in NW Ohio, USA was constructed to test the effects of climate change on water flow and sediment and nutrient loading within the drainage basin. The Maumee River drains a larger area (17,100 km2) than any other watershed in the Great Lakes region before discharging into the Western Basin (WB) of Lake Erie. Approximately 70% of the land within the watershed is agricultural, resulting in excess sediment and nutrient loading in the WB. High nutrient concentrations, especially phosphate concentrations, contribute to harmful algal blooms (HABs) in Lake Erie, which is the source of drinking water for approximately 11 million people. After a decrease in Lake Erie HABs in the late 1980s and early 1990s, toxic cyanobacteria blooms have been prevalent in the WB every summer since 1995. To determine the effects of climate change on streamflow and sediment and nutrient loading in the Maumee River watershed, a Soil and Water Assessment Tool (SWAT) hydrologic model was constructed. Flow and suspended sediment calibrations were performed for 1995-1999 using observed data from four USGS gauging stations. Suspended sediment concentration, which correlates highly with total phosphorus concentration, was used as a proxy for total phosphorus loads. Downscaled climate projections from the World Climate Research Programme's (WCRP's) Coupled Model Intercomparison Project phase 3 (CMIP3) were inputted into the model to test the effects of climate change on the flow and suspended sediment discharge of the Maumee River. Validation was performed by inputting downscaled climate data for 1975-1999 and comparing the output to observed flow and suspended sediment data from the USGS gauging station at Waterville, Ohio. Model outputs for A1B, A2, and B1 climate scenarios indicate an overall decrease in annual flow over the next century, with higher flow in the winter and spring and lower total flow in the summer. However, model outputs also indicate large runoff events will become more frequent in the summer months, providing significant nutrient loads when conditions for HABs are most prevalent. Downscaled climate projections were also used to predict future changes in the magnitude and timing of suspended sediment loads in the Maumee River watershed. Large pulses of nutrients during summer months could fuel large HABs, decreasing the water quality of the WB of Lake Erie.

  11. Effect of water-column pH on sediment-phosphorus release rates in Upper Klamath Lake, Oregon, 2001

    USGS Publications Warehouse

    Fisher, Lawrence H.; Wood, Tamara M.

    2004-01-01

    Sediment-phosphorus release rates as a function of pH were determined in laboratory experiments for sediment and water samples collected from Shoalwater Bay in Upper Klamath Lake, Oregon, in 2001. Aerial release rates for a stable sediment/water interface that is representative of the sediment surface area to water column volume ratio (1:3) observed in the lake and volumetric release rates for resuspended sediment events were determined at three different pH values (8.1, 9.2, 10.2). Ambient water column pH (8.1) was maintained by sparging study columns with atmospheric air. Elevation of the water column pH to 9.2 was achieved through the removal of dissolved carbon dioxide by sparging with carbon dioxide-reduced air, partially simulating water chemistry changes that occur during algal photosynthesis. Further elevation of the pH to 10.2 was achieved by the addition of sodium hydroxide, which doubled average alkalinities in the study columns from about 1 to 2 milliequivalents per liter. Upper Klamath Lake sediments collected from the lake bottom and then placed in contact with lake water, either at a stable sediment/water interface or by resuspension, exhibited an initial capacity to take up soluble reactive phosphorus (SRP) from the water column rather than release phosphorus to the water column. At a higher pH this initial uptake of phosphorus is slowed, but not stopped. This initial phase was followed by a reversal in which the sediments began to release SRP back into the water column. The release rate of phosphorus 30 to 40 days after suspension of sediments in the columns was 0.5 mg/L/day (micrograms per liter per day) at pH 8, and 0.9 mg/L/day at pH 10, indicating that the higher pH increased the rate of phosphorus release by a factor of about two. The highest determined rate of release was approximately 10% (percent) of the rate required to explain the annual internal loading to Upper Klamath Lake from the sediments as calculated from a lake-wide mass balance and observed in total phosphorus data collected at individual locations.

  12. As was hypothesized, annual ET water losses appears to be driven by seasonal variations in the total aboveground biomass of the treatment wetland. We found that only air temperature and PAR were significant climatic drivers of ET. However, unlike

    E-print Network

    Hall, Sharon J.

    shore-to-open-water transects were distributed proportionally across a treatment flow cell based.T.A. 2003. Water and mass budgets of a vertical=-flow constructed wetland used for wastewater treatment· As was hypothesized, annual ET water losses appears to be driven by seasonal variations

  13. Hydrodynamic forcing and sediment character in Boston Harbor

    USGS Publications Warehouse

    Ravens, T.M.; Madsen, O.S.; Signell, R.P.; Adams, E.E.; Gschwend, P.M.

    1998-01-01

    Calculated annual excess skin friction stress at various locations in Quincy Bay (outer Boston Harbor) was found to be correlated positively with sediment sand content. The correlation was optimized when a critical shear stress (??c) of 0.085 Pa was assumed for the bay. The excess shear stress was correlated negatively with sediment lead (Pb) and polychlorinated biphenyl (PCB) concentrations. These correlations suggest that area surveys of properties like sand content may be sufficient to estimate ??C.

  14. Sediment accumulation of organic halogens in pristine forest lakes

    Microsoft Academic Search

    Kimmo P. Suominen; Timo Jaakkola; Eila Elomaa; Risto Hakulinen; Mirja S. Salkinoja-Salonen

    1997-01-01

    Sediment accumulation of organic halogen was studied in two forest lakes, one pristine and one which received 30 m3 of biologically purified bleaching wastewater from a kraft pulp mill in 1979 equivalent to ca. 2 kg of adsorbable organic\\u000a halogen (AOX). Lake sediments were dated with210Pb,134Cs and137Cs and the annual deposition rates of organic halogens and organic matter were calculated.

  15. Global Overview On Delivery Of Sediment To The Coast From Tropical River Basins

    NASA Astrophysics Data System (ADS)

    Syvitski, J. P.; Kettner, A. J.; Brakenridge, G. R.

    2011-12-01

    Depending on definition, the tropics occupy between 16% and 19% of the earth's land surface, and discharge ~18.5% of the earth's fluvial water runoff. These flow regimes are driven by three types of sub-regional climate: rainforest, monsoon, and savannah. Even though the tropics include extreme precipitation events, particularly for the SE Asian islands, the general rainfall pattern alternates between wet and dry seasons as the ITCZ follows the sun and where annual monsoonal rain occurs. ITCZ convective rainfall is the dominant style of precipitation but this can be influenced by rare intra-tropical cyclone events, and by atmospheric river events set up by strong monsoonal conditions. Though a rainy season is normal (for example, portions of India discharge in summer may reach 50 times that of winter), the actual rainfall events are in the form of short bursts of precipitation (hours to days) separated by periods of dry (hours to weeks). Some areas of the tropics receive more than 100 thunderstorms per year. Rivers respond to this punctuated weather by seasonal flooding. For the smaller island nations and locales (e.g. Indonesia, Philippines, Borneo, Hainan, PNG, Madagascar, Hawaii, Taiwan) flash floods are common. Larger tropical river systems (Niger, Ganges, Brahmaputra, Congo, Amazon, Orinoco, Magdalena) show typical seasonally modulated discharges. The sediment flux from tropical rivers is approximately 17% to 19% of the global total - however individual river basins offer a wide range in sediment yields reflecting highly variable differences in their hinterland lithology, tectonic activity and volcanism, land-sliding, and relief. Human influences also greatly influence the range for tropical river sediment yield. Some SE Asian Rivers continue to be greatly affected by deforestation, road construction, and monoculture plantations. Sediment flux is more than twice the pre-Anthropocene flux in many of these SE Asian countries, especially where dams and reservoir emplacements do not impact sediment delivery, as is the case in most temperate regions.

  16. Co-occurrence correlations of heavy metals in sediments revealed using network analysis.

    PubMed

    Liu, Lili; Wang, Zhiping; Ju, Feng; Zhang, Tong

    2015-01-01

    In this study, the correlation-based study was used to identify the co-occurrence correlations among metals in marine sediment of Hong Kong, based on the long-term (from 1991 to 2011) temporal and spatial monitoring data. 14 stations out of the total 45 marine sediment monitoring stations were selected from three representative areas, including Deep Bay, Victoria Harbour and Mirs Bay. Firstly, Spearman's rank correlation-based network analysis was conducted as the first step to identify the co-occurrence correlations of metals from raw metadata, and then for further analysis using the normalized metadata. The correlations patterns obtained by network were consistent with those obtained by the other statistic normalization methods, including annual ratios, R-squared coefficient and Pearson correlation coefficient. Both Deep Bay and Victoria Harbour have been polluted by heavy metals, especially for Pb and Cu, which showed strong co-occurrence with other heavy metals (e.g. Cr, Ni, Zn and etc.) and little correlations with the reference parameters (Fe or Al). For Mirs Bay, which has better marine sediment quality compared with Deep Bay and Victoria Harbour, the co-occurrence patterns revealed by network analysis indicated that the metals in sediment dominantly followed the natural geography process. Besides the wide applications in biology, sociology and informatics, it is the first time to apply network analysis in the researches of environment pollutions. This study demonstrated its powerful application for revealing the co-occurrence correlations among heavy metals in marine sediments, which could be further applied for other pollutants in various environment systems. PMID:24559934

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

    USGS Publications Warehouse

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

    2010-01-01

    Coastal sediments in many regions are impacted by high levels of contaminants. Due to a combination of shallow water depths, waves, and currents, these sediments are subject to regular episodes of sediment resuspension. However, the influence of such disturbances on sediment chemistry and the release of solutes is poorly understood. The aim of this study is to quantify the release of dissolved metals (iron, manganese, silver, copper, and lead) and nutrients due to resuspension in Boston Harbor, Massachusetts, USA. Using a laboratory-based erosion chamber, a range of typical shear stresses was applied to fine-grained Harbor sediments and the solute concentration at each shear stress was measured. At low shear stress, below the erosion threshold, limited solutes were released. Beyond the erosion threshold, a release of all solutes, except lead, was observed and the concentrations increased with shear stress. The release was greater than could be accounted for by conservative mixing of porewaters into the overlying water, suggesting that sediment resuspension enhances the release of nutrients and metals to the dissolved phase. To address the long-term fate of resuspended particles, samples from the erosion chamber were maintained in suspension for 90. h. Over this time, 5-7% of the particulate copper and silver was released to the dissolved phase, while manganese was removed from solution. Thus resuspension releases solutes both during erosion events and over a longer timescale due to reactions of suspended particles in the water column. The magnitude of the annual solute release during erosion events was estimated by coupling the erosion chamber results with a record of bottom shear stresses simulated by a hydrodynamic model. The release of dissolved copper, lead, and phosphate due to resuspension is between 2% and 10% of the total (dissolved plus particulate phase) known inputs to Boston Harbor. Sediment resuspension is responsible for transferring a significant quantity of solid phase metals to the more bioavailable and mobile dissolved phase. The relative importance of sediment resuspension as a source of dissolved metals to Boston Harbor is expected to increase as continuing pollutant control decreases the inputs from other sources. ?? 2010 Elsevier B.V.

  18. Wetland sedimentation from hurricanes Katrina and Rita.

    PubMed

    Turner, R Eugene; Baustian, Joseph J; Swenson, Erick M; Spicer, Jennifer S

    2006-10-20

    More than 131 x 10(6) metric tons (MT) of inorganic sediments accumulated in coastal wetlands when Hurricanes Katrina and Rita crossed the Louisiana coast in 2005, plus another 281 x 10(6) MT when accumulation was prorated for open water area. The annualized combined amount of inorganic sediments per hurricane equals (i) 12% of the Mississippi River's suspended load, (ii) 5.5 times the inorganic load delivered by overbank flooding before flood protection levees were constructed, and (iii) 227 times the amount introduced by a river diversion built for wetland restoration. The accumulation from hurricanes is sufficient to account for all the inorganic sediments in healthy saltmarsh wetlands. PMID:16990516

  19. Assessment the spatial and temporary variability of sediments production taken into account the land use and the climate change, In the Paute river basin southern Ecuador

    NASA Astrophysics Data System (ADS)

    Cisneros, F.; Pacheco, E.; Coello, C.; Wyseure, G.

    2012-04-01

    Erosion processes and sediment production data for The Paute river basin watershed (5000 km2) located the south of Ecuador, are analyzed, its importance is in the hydroelectric sector in which the project generates 1200 Mw and that correspond approximately to 55% of the energy for the Ecuador. The anthropogenic intervention, the watershed geomorphologic characteristics, added to the great variability of present land use and to the non-uniform space and temporary distribution of the hydrologic events; contribute to the permanence of the erosive processes of formation of gullies, progressive degradation of land cover that is translated in a constant production of sediments. According to the load of suspended sediment monitoring campaign, values like 90% of the total production would occur during the rainy time and in very little number of variable intensities events, from this data, between 40% to 50% show values up to 25 mm h-1. Therefore it has been taken as an important criterion the Rain fall regime and the annual sediment production. Considering the later results, a scheme for projection of rates of erosion and sediment production has been settled down taken into account factors as: Regime and annual Rainfall average; Land cover type and its surface, and Space zoning of vulnerable areas. According to the degraded areas assessment and considering the current rainfall conditions regime and its land cover, and the available evidence with respect to the influence of the presence or absence of a good forest cover on rainfall it was settled down rates of erosion for the regional projection four main zones with the following ranks of annual erosion: i) natural zones < 5 t ha-1 a-1, II) zones of anthropogenic intervention from 5 to 50 t ha-1 a-1, III) zones of moderate erosion from 50 to 100 t has-1 a-1, and IV) high rates erosion zones > 100 t ha-1 a-1. Starting on 2010 is operating Mazar reservoir in the retention of sediments as support to Amaluza reservoir and therefore beneficial to increase the useful life of the dam that at the present time. The aim of the present paper is to establish if the impact of the processes of erosion and sedimentation in the Paute river basin would have direct consequences in the hydroelectric production and useful life of the dams; a scenario analysis of erosion processes with respect to main works of water retention for hydroelectrically production of the zone was done, the temporary scale of the analysis of sediments has been considered from year 2010 to year 2030; Using ECHAM A2 and the ECHAM B2 climate change scenarios.

  20. Predicting reservoir sedimentation 

    E-print Network

    Wooten, Stephanie

    1997-01-01

    Assessment Tool (SWAT) watershed model for developing relationships between streamflow discharge and sediment load, (2) use of historical sediment accumulation amounts determined from hydrographic surveys to adjust parameters in the watershed model, (3...

  1. A model to predict annual bed load transport in ungauged watersheds

    NASA Astrophysics Data System (ADS)

    Segura, C.; Pitlick, J.

    2014-12-01

    The prediction of bed load transport is relevant to many aspects of river management such as river engineering, channel stability, and stream ecology. However, given that the functions used to predict bed load transport are very sensitive to input values, the uncertainty associated with estimates of transport at a specific place or point in time can be quite large. In addition, if the goal is to predict annual loads, a distribution characterizing the frequency of sediment-transporting flows must also be known. In this work we develop a model to predict annual bed load transport in ungauged catchments by computing the sediment movement associated with discharge levels between ½ of bankfull and bankfull flow. The model incorporates both the prediction of daily flows based on a power function, and a field-based parameterization of the spatial-temporal distribution of boundary shear stress based on two-dimensional flow modelling. The data inputs for the model are channel geometry (depth, width, and slope), grain size distribution, and drainage area. We will present the results sites in Colorado and Idaho. The model can be used to explore how changes in the frequency of extreme events impacts the total annual bed load and the spatial-temporal disturbance regime of aquatic ecosystems.

  2. Testing the potential of 10Be in varved sediments from two lakes for solar activity reconstruction

    NASA Astrophysics Data System (ADS)

    Czymzik, Markus; Muscheler, Raimund; Brauer, Achim; Adolphi, Florian; Ott, Florian; Kienel, Ulrike; Dräger, Nadine; Slowinski, Michal; Aldahan, Ala; Possnert, Göran

    2015-04-01

    The potential of 10Be in annually laminated (varved) lake sediments for solar activity reconstruction is, to date, largely unexplored. It is hypothesized that 10Be contents in sediments from well-chosen lakes reflect the solar induced atmospheric production signal. The varved nature of these archives provides the chance to establish solar activity time-series with very high temporal precision. However, so far solar activity reconstruction from 10Be in varved lake sediments is hampered due to a lack of detailed knowledge of the process chain from production in the atmosphere to deposition on the lake floor. Calibrating 10Be time-series from varved lake sediments against complementary proxy records from the same sediment archive as well as instrumental meteorological and solar activity data will allow a process-based understanding of 10Be deposition in these lakes and a quantitative evaluation of their potential for solar activity reconstruction. 10Be concentration and flux time-series at annual resolution were constructed for the period 1983 to 2007 (approx. solar cycles 22 and 23) conducting accelerator mass spectrometry and varve chronology on varved sediments of Lakes Tiefer See and Czechowski, located on an east-west transect at a distance of about 450 km in the lowlands of northern-central Europe. 10Be concentrations vary between 0.9 and 1.8*108atoms/g, with a mean of 1.3*108atoms/g in Lake Tiefer See and between 0.6 and 1.6*108atoms/g, with a mean of 1*108atoms/g in Lake Czechowski. Calculated mean 10Be flux is 2.3*108atoms/cm2/year for Lake Tiefer See and 0.7*108atoms/cm2/year for Lake Czechowski. Calibrating the 10Be time-series against corresponding geochemical ?-XRF profiles, varve thickness and total organic carbon records as well as precipitation data from the nearby stations Schwerin for Lake Tiefer See and Koscierzyna for Lake Czechowski and a neutron monitor record of solar activity suggests (1) a complex interaction of varying processes influencing 10Be deposition in both lakes and (2) that neither 10Be concentrations nor fluxes are the most suitable indicator of solar variability alone. Multiple regression analyses indicate that the combined 10Be concentration and flux time-series account for about 80% (Tiefer See) and 40% (Lake Czechowski) of the variability in the neutron monitor record, sufficient to reconstruct variability related to the 11-year solar cycle.

  3. Sediment P in Agricultural Streams: Response to Land Use and Influence on TP Export

    NASA Astrophysics Data System (ADS)

    Rosamond, Madeline; Mohamed, Mohamed; Taylor, William

    2015-04-01

    Phosphorus export from agricultural streams can be a significant source to downstream water bodies, contributing to eutrophication, algal blooms and hypoxia. Sediment in agricultural streams can have very high P concentrations and has been proposed as a significant source of P to the water column though bioavailability can be low. Recent work suggests that sediments can sorb P from point sources such as WWTPs, and release this P during disturbances such as high flow events. However, it is unclear if sediment P responds to increased P application to the landscape, or if it is a significant source of P to annual TP export from agricultural streams. We examined 15 streams in southern Ontario, Canada, in highly agricultural catchments, comparing stream sediment P concentration to sediment geochemistry, P application, runoff, tile drainage, water column TP concentration and TP export. Stream sediment P was well correlated to sediment Fe and C and to tile drainage, and weakly correlated to manure P. This could suggest that sediment P responds to P addition, and may temporarily store P incoming from agricultural sources. Annual TP export was not correlated to stream sediment P concentration but was well correlated with runoff and tile drainage. This suggests P stored in sediment is a minor contributor to annual TP export. Effective agricultural P management strategies include implementing drainage water management, buffer zones etc. in catchments with high runoff and tile drainage.

  4. Sulfhydrolase Activity in Sediments of Wintergreen Lake, Kalamazoo County, Michigan †

    PubMed Central

    King, Gary M.; Klug, Michael J.

    1980-01-01

    The hydrolysis of p-nitrophenyl sulfate, p-nitrocatechol sulfate, and [35S]sodium dodecyl sulfate was examined in anoxic sediments of Wintergreen Lake, Michigan. Significant levels of sulfhydrolase activity were observed in littoral, transition, and profundal sediment samples. Rates of sulfate formation suggest that the sulfhydrolase system would represent a major source of sulfate within these sediments. Sulfate formed by ester sulfate hydrolysis can support dissimilatory sulfate reduction as shown by the incorporation of 35S from labeled sodium dodecyl sulfate into H235S. Sulfhydrolase activity varied with sediment depth, was greatest in the littoral zone, and was sensitive to the presence of oxygen. Estimations of ester sulfate concentrations in sediments revealed large quantities of ester sulfate (?30% of total sulfur). Both total sulfur and ester sulfate concentrations varied with the sediment type and were two to three orders of magnitude greater than the inorganic sulfur concentration. PMID:16345573

  5. Evaluations of bioavailable copper in amended wetland sediments

    SciTech Connect

    Deaver, E.; Rodgers, J.H. Jr. [Univ. of Mississippi, University, MS (United States)

    1994-12-31

    Copper sulfate was added to the water column of six of twelve wetland mesocosms. In successive 10d experiments using invertebrates Hyalella azteca and Chironomus tentans, sediment toxicity and copper bioavailability were examined in sediments collected monthly from wetlands amended with copper sulfate, untreated wetlands, and control sediments. Evaluations included examinations of temporal changes in toxicity, bioavailability of aqueous and sediment associated copper, and comparison of organism responses to copper. In some cases copper remained acutely toxic over the 6 month study period, however, total copper concentrations in sediment had no relation to bioavailable copper. The relationship of copper speciation to bioavailability was discerned by measuring total copper (AA), labile copper (ASV) and copper ion activity (ISE) during these sediment toxicity experiments.

  6. Low phosphorus sediments in a hypersaline marine bay

    NASA Astrophysics Data System (ADS)

    Atkinson, M. J.

    1987-03-01

    Shark Bay, Western Australia is a large, shallow, hypersaline coastal lagoon with low nutrient input. Dissolved inorganic P in the water column decreased from 0·2 ? M in the oceanic region of the bay to undetectable limits in the hypersaline areas of the bay. Organic C, total N, and total P were measured in the sediments along the salinity gradient. The sediment organic C was 1-3 mmol C g -1 and increased into the bay; total N was positively correlated with C; but P decreased from 15 ?mol P g -1 in the outer bay to less than 1 ?mol P g -1 in the hypersaline region. Sediment inorganic P comprised 80-90% of the total sediment P. The molar C:P ratio of the sediment organic phase increased from 1700 in the outer bay to 12 000 in the hypersaline region. Organic C and total P were also measured in the benthic plants. P content of the plants also decreased as salinity increased, resulting in an increase in the plant C:P ratio which was similar to the increase in the C:P ratio of the sediment organic phase. P composition of the coastal sediments can change dramatically in a relatively short distance as a result of net uptake and sedimentation by benthic communities.

  7. Sedimentation in Goose Pasture Tarn, 1965-2005, Breckenridge, Colorado

    USGS Publications Warehouse

    Elliott, John G.; Char, Stephen J.; Linhart, Samuel M.; Stephens, V. Cory; O'Neill, Gregory B.

    2006-01-01

    Goose Pasture Tarn, a 771-acre-foot reservoir in Summit County, Colorado, is the principal domestic water-storage facility for the Town of Breckenridge and collects runoff from approximately 42 square miles of the upper Blue River watershed. In the 40 years since the reservoir was constructed, deltaic deposits have accumulated at the mouths of two perennial streams that provide most of the inflow and sediment to the reservoir. The Blue River is a low-gradient braided channel and transports gravel- to silt-size sediment. Indiana Creek is a steep-gradient channel that transports boulder- to silt-size sediment. Both deltas are composed predominantly of gravel, sand, and silt, but silt has been deposited throughout the reservoir. In 2004, the U.S. Geological Survey, in cooperation with the Town of Breckenridge, began a study to determine the volume of accumulated sediment in Goose Pasture Tarn, the long-term sedimentation rate for the reservoir, and the particle-size and chemical characteristics of the sediment. Exposed delta deposits occupied 0.91 acre and had an estimated volume of 0.6 acre-foot in 2005. Aerial photographic analysis indicated both the Blue River and Indiana Creek deltas grew rapidly during time intervals that included larger-than-average annual flood peaks on the Blue River. Sediment-transport relations could not be developed for the Blue River or Indiana Creek because of minimal streamflow and infrequently observed sediment transport during the study; however, suspended-sediment loads ranged from 0.02 to 1.60 tons per day in the Blue River and from 0.06 to 1.55 tons per day in Indiana Creek. Bedload as a percentage of total load ranged from 9 to 27 percent. New reservoir stage-area and stage-capacity relations were developed from bathymetric and topographic surveys of the reservoir bed. The original 1965 reservoir bed topography and the accumulated sediment thickness were estimated from a seismic survey and manual probing. The surface area of Goose Pasture Tarn in 2005 was 66.4 acres, and the reservoir capacity was 771.1 acre-feet at a full-pool elevation of 9,886.4 feet. The 1965 surface area was 67.1 acres, and the reservoir capacity was 818.0 acre-feet, indicating that the reservoir surface area has decreased by 0.7 acre, or about 1.1 percent, and the reservoir capacity has decreased by 46.9 acre-feet, or about 5.7 percent over a 40-year period. Sediment thickness determined with seismic profiling ranged from 0 to 4.0 feet and averaged 0.7 foot, with lesser thicknesses in the deeper parts of the reservoir and greater thicknesses near the deltas. Probe-determined sediment thickness ranged from 1.0 to 4.4 feet and averaged 2.8 feet near the Blue River delta and ranged from 0.3 to 6.0 feet and averaged 3.6 feet near the Indiana Creek delta. Approximately 47.5 acre-feet of sediment has accumulated in Goose Pasture Tarn and in the Blue River and Indiana Creek deltas, or an average of 1.19 acre-feet per year. Sediment cores from several locations in the reservoir showed stratification, which is indicative of different depositional dates or mechanisms. Metal and trace-constituent levels from the cores were compared with three standards. Silver, cadmium, europium, lead, and zinc were present in greater concentrations than Southern Rocky Mountain background levels in four sediment cores, and cadmium, lead, and zinc levels also were equal to or exceeded the Threshold Effect Concentration standards. Lead exceeded the Probable Effect Concentration standard in silt from the Blue River delta and deep water near the north shore. Tin was present in greater concentrations than Southern Rocky Mountain background levels in deep water near the east shore, and chromium and copper levels were equal to or exceeded the Threshold Effect Concentration standards in these cores.

  8. Evaluation of proposed sediment quality criteria for metals in marine and freshwater surficial sediments

    SciTech Connect

    Hoke, R. [Science Applications International Corp., Hackensack, NJ (United States); Leonard, E.; Ankley, G. [Environmental Protection Agency, Duluth, MN (United States)

    1995-12-31

    A proposed approach to sediment quality criteria (SQC) for five metals (copper, cadmium, zinc, nickel, and lead) was evaluated with surficial sediments collected from Lake Michigan and the Virginian Province of the east coast of the US Environmental Monitoring and Assessment Program of the US Environmental Protection Agency. Concentrations of acid volatile sulfide (AVS), simultaneously extracted metals (SEM), total metals, and total organic carbon were measured in the sediments. Interstitial (pore) water concentrations of the five metals also were measured in the freshwater sediment samples. Overall, > 90% and 59% of surficial marine and freshwater sediments contained detectable AVS, respectively. Approximately 90% of the marine sediments contained greater concentrations of AVS that total SEM (molar sum of copper, cadmium, zinc, nickel, and lead); suggesting minimal bioavailability of the five metals. A smaller proportion of the freshwater samples (30%) contained greater concentrations of AVS than total SEM. However, pore water concentrations of the five metals were uniformly low and never exceeded approximately 0.3 toxic units using an additive toxicity model based on Final Chronic Values from EPA Water Quality Criteria.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  10. Fugacity approach to evaluate the sediment-water diffusion of polycyclic aromatic hydrocarbons.

    PubMed

    Wang, De-Gao; Alaee, Mehran; Byer, Jonathan; Liu, Yong-Jun; Tian, Chong-Guo

    2011-06-01

    Diffusion is an important process for sediment-water exchange and plays a vital role in controlling water quality. Fugacity fraction (ff) was used to estimate the sediment-water diffusion of polycyclic aromatic hydrocarbons (PAHs) between seawater and surficial sediment. A total of 33 surface sediment and sea water samples were collected concurrently from the northeast coastal area in China and 25 PAHs were analyzed including the alkylated and chlorated PAHs. Fugacity fraction was calculated based on the PAH concentrations in water and sediment, octanol-water partition coefficient of PAHs, organic matter content in sediment, and density of sediment. The calculated results showed that ff increased with decreasing molecular weight of PAHs. The low molecular weight PAHs (2-3 rings) transferred from sediment to water and the sediment acted as a secondary source to the water. The medium molecular weight PAHs (4-5 rings) were close to the sediment-water equilibrium and the transfer tendency shifted between sediment and water. The high molecular weight PAHs (5-6 rings) transferred from water into sediment and the sediment acted as a sink. Soot carbon and the difference of PAH concentrations between sediment and water were found to be important factors affecting the sediment-water diffusion. This study provided new insight into the process of sediment-water diffusion, which has a great influence on the quality of water, especially in severely-polluted sediment areas. PMID:21552633

  11. Splash-Saltation of Sand due to Wind-Driven Rain: Horizontal Flux and Sediment Transport Rate

    Microsoft Academic Search

    Wim M. Cornelis; Greet Oltenfreiter; Donald Gabriels; Roger Hartmann

    attempts were made to measure and model the sediment mass transport rates. Transport of sediment under wind-driven rains is generally not To predict the total budget of sediment transported accounted for in equations for sediment transport by wind. However, by wind over a given period, it is necessary not only to the contribution of this rainsplash-saltation process can be substantial.

  12. Modeling sediment entrainment and transport processes limited by bed armoring

    Microsoft Academic Search

    Christopher W. Reed; Alan W. Niedoroda; Donald J. P. Swift

    1999-01-01

    A sediment-transport model including a bed-armoring algorithm is used to ascertain the potential importance of bed-armoring processes. The parameters that control the bed-armoring effects on the suspension of granular sediments in the marine environment are examined using the numerical model and data from the Eel shelf. Results for the shelf indicate that bed armoring controls the total suspended-sediment load and

  13. Annual maximum 5-day rainfall total and maximum number of consecutive dry days over Central America and the Caribbean in the late twenty-first century projected by an atmospheric general circulation model with three different horizontal resolutions

    NASA Astrophysics Data System (ADS)

    Nakaegawa, T.; Kitoh, A.; Murakami, H.; Kusunoki, S.

    2014-04-01

    We simulated changes in annual maximum 5-day rainfall (RX5D) and annual maximum number of consecutive dry days (CDD) in Central America, Mexico, and the Caribbean with three different horizontal resolution atmospheric global general circulation models (AGCMs) and quantified the uncertainty of the projections. The RX5Ds and CDDs were projected to increase in most areas in response to global warming. However, consistent changes were confined to small areas: for RX5D, both coastal zones of northern Mexico and the Yucatan Peninsula; for CDD, the Pacific coastal zone of Mexico, the Yucatan Peninsula, and Guatemala. All three AGCMs projected that RX5Ds and CDDs averaged over only the land area and over the entire area (land and ocean) would increase. The dependence of RX5D probability density functions on the horizontal resolutions was complex. Precipitation unrelated to tropical cyclones was primarily responsible for the projected increases in the frequency of RX5Ds greater than 300 mm.

  14. Establishing Catchment Sediment Budgets

    NASA Astrophysics Data System (ADS)

    Walling, D. E.; Collins, A. L.

    2005-12-01

    The sediment budget concept, first introduced more than 40 years ago, is of fundamental importance to an understanding of the interaction between sediment mobilization, delivery, storage and yield within a catchment, and such understanding is a key requirement for designing effective sediment control and management strategies. However, despite its importance as a concept, from both a scientific and management perspective, there have to date been few successful attempts to establish detailed sediment budgets for individual catchments. Arguably, therefore, the sediment budget concept has yet to be fully exploited as a practical or operational tool within a management context. Recent advances in monitoring sediment loads, establishing sediment sources, documenting sediment mobilisation and storage on the slopes of a catchment and quantifying storage on river floodplains, in river channels and in other sediment sinks have, however, greatly advanced the potential for establishing reliable sediment budgets for small and intermediate sized catchments. In particular, the use of environmental or fallout radionuclides to trace sediment mobilization and transfer within a drainage basin has provided important new opportunities for obtaining spatially distributed and temporally integrated data on sediment mobilization, delivery and storage. Several examples of the application of these and related techniques to the establishment of sediment budgets for small and intermediate sized agricultural catchments in both the UK and overseas (e.g. Africa) will be presented. Despite such advances, significant problems still remain. These include the need to reconcile the different levels of temporal resolution associated with different techniques, and the inability to effect a rigorous budget closure in most investigations. The need for further work in developing techniques for establishing sediment budgets and in facilitating the application of the sediment budget concept as an operational tool will be reviewed.

  15. Erosion risk assessment and sediment yield production of the King Talal Watershed, Jordan

    Microsoft Academic Search

    M. S. Al-Sheriadeh; A. Z. Al-Hamdan

    1999-01-01

    King Talal Dam (KTD) watershed is the most important one in Jordan. At its outlet lies the KTD (80 MCM capacity) which serves\\u000a irrigation purposes in the Jordan Valley. However, the dam suffers from accelerated annual sedimentation. Therefore, this\\u000a study is directed to assess the erosion risk over the watershed, and to simulate actual annual sediment yield at the dam

  16. Lipid composition and vertical distribution of bacteria in aerobic sediments of the Venezuela Basin

    NASA Astrophysics Data System (ADS)

    Harvey, H. Rodger; Richardson, Michael D.; Patton, John S.

    1984-04-01

    Box cores of surface (0 to 30-cm) sediments from carbonate, hemipelagic, and turbidite sediment types of the deep (3493 to 5039-m) Venezuelan Basin were analyzed to investigate the relationship between the vertical distribution of bacteria, lipids, lipid phosphate, and grain size. The polar lipid fraction was isolated chromatographically and quantified by flame-ionization detection using the Iatroscan TH-10 analyzer. Total bacterial abundance was measured by epifluorescence microscopy in sediments (0 to 20-cm) from the carbonate and turbidite sediments. In all three sediment types investigated, both total and polar lipid concentrations decreased with increasing depth in the sediment. The highest total and polar lipid concentrations were at the sediment-water interface (0 to 2-cm) of hemipelagic sediments (62.0 and 25.7 ?g g -1 dry sediment, respectively) followed by the carbonate and turbidite sediments. A similar decline in lipid phosphate was also observed. Bacterial abundance was > 5 × 10 8 bacteria (per gram dry sediment) at the sediment surface in both sediments examined and over 1 × 10 7 bacteria 20 cm below the sediment-water interface. Polar lipid and lipid phosphate concentrations did not appear to correlate with estimates of bacterial biomass, even in regions where bacteria were apparently the only organisms present.

  17. Let's Bet on Sediments

    NSDL National Science Digital Library

    In their investigation of Hudson Canyon sediments, students will discover how sediment size is related to the amount of time the sediment is suspended in water. During this activity, students will investigate and analyze the patterns of sedimentation in the Hudson Canyon off the Atlantic coast of North America. They will observe how heavier particles sink faster than finer particles, learn that submarine landslides (trench slope failures) are sediment "avalanches" that occur in deep-ocean canyons, and infer that the passive side of a continental margin is not as geologically static as scientists previously believed. Students will also discover that when sediments such as sand, dirt, silt, and other fine particles become suspended in water by currents, the water becomes murky, or turbid and then may become a turbidity current, which is a down-slope movements of sediment-laden water that continuously erodes many submarine canyons such as the Hudson Canyon.

  18. Annual Report FY2012 University of Rhode Island

    E-print Network

    Rhode Island, University of

    $5.2 Energy $4.4 INT $1.1 Other $1.1 EDUC $.8 NASA $.7 EPA $.6 #12;Annual Report FY2012 3.4 AwardsAnnual Report FY2012 University of Rhode Island Division of Research and Economic Development 3 - FY2012 Totals in $Millions ARRA Awards Total Awards Non- ARRA #12;Annual Report FY2012 University

  19. Erosion and sedimentation research in agricultural watersheds in the USA: From past to present and beyond

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In ancient times, sediment and sedimentation were a blessing that brought fertility to the land and made it possible for people to live and prosper. This is the story of the Egyptians in the Nile Delta where they lived this way for thousands of years in harmony with annual floods that brought soil a...

  20. Effects of sediment mixing and benthic algal production on fossil pigment stratigraphies

    Microsoft Academic Search

    P. R. Leavitt; S. R. Carpenter

    1989-01-01

    Effects of sediment mixing and benthic algal production on fossil pigment profiles were quantified by fine-interval analysis of cores in a transect across the basin of Paul Lake, MI. Annually resolved profiles (1957–1986) of carotenoids and chlorophyll a from varved sediments at deepwater (15 m) sites were compared to fine-interval (2.5–3.5 mm) stratigraphies from sites with increasing sediment mixing and

  1. Fluorescent dissolved organic matter in marine sediment pore waters

    E-print Network

    Burdige, David

    ­water interface. Furthermore, the interplay between transport processes and the depth zonation of DOM cycling with sediment depth at almost all stations, and was closely correlated with total DOC. This fluorescence with depth during sediment diagenesis. Fluorescence­DOC relationships indicated that larger relative amounts

  2. EAOG Sville The fate of organic matter in mangrove sediments

    E-print Network

    Boyer, Edmond

    plants specific to these swamps. An elemental, pyrolytic and optical study of total sedimentary organic sediment only contains minute refractory debris of higher plants supplied with clay minerals of redox processes (oxic- suboxic-anoxic) and to strong variations of surface sediments salinity. In older

  3. Methane cycling in the sediments of Lake Washington

    Microsoft Academic Search

    K. M. KUIVILA; J. W. MURRAY; A. H. DEVOL; M. E. LIDSTROM; C. E. REIMERS

    1988-01-01

    Aerobic oxidation is important in the cycling of methane in the sediments of Lake Washington. About half of the methane flux from depth is oxidized to CO, in the upper 0.7 cm of the sediments and the remainder escapes into the water column. In terms of the total carbon budget of the lake, the upward flux of methane is insignificant

  4. Controls on flood and sediment wave propagation

    NASA Astrophysics Data System (ADS)

    Bakker, Maarten; Lane, Stuart N.; Costa, Anna; Molnar, Peter

    2015-04-01

    The understanding of flood wave propagation - celerity and transformation - through a fluvial system is of generic importance for flood forecasting/mitigation. In association with flood wave propagation, sediment wave propagation may induce local erosion and sedimentation, which will affect infrastructure and riparian natural habitats. Through analysing flood and sediment wave propagation, we gain insight in temporal changes in transport capacity (the flood wave) and sediment availability and transport (the sediment wave) along the river channel. Heidel (1956) was amongst the first to discuss the progressive lag of sediment concentration behind the corresponding flood wave based on field measurements. Since then this type of hysteresis has been characterized in a number of studies, but these were often based on limited amount of floods and measurement sites, giving insufficient insight into associated forcing mechanisms. Here, as part of a project concerned with the hydrological and geomorphic forcing of sediment transfer processes in alpine environments, we model the downstream propagation of short duration, high frequency releases of water and sediment (purges) from a flow intake in the Borgne d'Arolla River in south-west Switzerland. A total of >50 events were measured at 1 minute time intervals using pressure transducers and turbidity probes at a number of sites along the river. We show that flood and sediment wave propagation can be well represented through simple convection diffusion models. The models are calibrated/validated to describe the set of measured waves and used to explain the observed variation in wave celerity and diffusion. In addition we explore the effects of controlling factors including initial flow depth, flood height, flood duration, bed roughness, bed slope and initial sediment concentration, on the wave propagation processes. We show that the effects of forcing mechanisms on flood and sediment wave propagation will lead to different temporal and spatial erosion and deposition patterns. Knowledge of these forcing mechanisms and flood and sediment wave propagation in general can be applied in flow management and infrastructural/ecological development along the river. Heidel, S. G. (1956). "The progressive lag of sediment concentration with flood waves." Eos, Transactions American Geophysical Union 37(1): 56-66.

  5. Characterization of Siberian Arctic coastal sediments: Implications for terrestrial organic carbon export

    E-print Network

    Guo, Laodong

    were characterized for elemental composition (total organic carbon, TOC, black carbon, BC, and total NCharacterization of Siberian Arctic coastal sediments: Implications for terrestrial organic carbon of the Siberian Arctic. On average, 79 ± 9% of the total C in sediments was organic while 21 ± 9% was inorganic

  6. Petrographic and geochemical study of organic matter in surficial laminated sediments from an upwelling system

    E-print Network

    Paris-Sud XI, Université de

    . Sedimentary units dominated by light laminations have low values of total organic carbon, total nitrogen in the bottom sediments. In contrast, a unit rich in dark laminations with high values of total organic carbon of biogenic remains. Thus, in this kind of environment the organic carbon content of sediments may reach 10

  7. Seasonal dynamics of the North Sea sediments using a three-dimensional coupled sediment-water model system

    NASA Astrophysics Data System (ADS)

    Luff, Roger; Moll, Andreas

    2004-06-01

    A high-resolution early diagenetic model for the North Sea sediments has been coupled with a pelagic ecosystem model to quantify the three-dimensional processes in the coupled sediment-water system from the sea surface to a sediment depth of 11 cm focussing on the processes in the sediments of the North Sea. The pelagic ecosystem model ECOHAM1 simulates the 1986 phytoplankton dynamics considering circulation, temperature, nutrient availability in the water column and the resulting flux of particulate organic carbon (POC) onto the sediment. These seasonal and regional variable water column processes are considered as forcing for the early diagenetic model C. CANDI, which calculates the processes in the upper sediment column, represented by 14 dissolved and 6 solid species, resolved with 84 vertical levels. With the coupled model the daily benthic fluxes of POC, oxygen, nitrate, phosphate, and sulphate at the sediment-water interface for each of the 1158 horizontal cells covering the whole North Sea area has been determined. The simulations show the seasonal and regional variations in the pelagic and the sediment system. The coupled model reproduces very well measured oxygen and nitrate penetration depths at selected validation stations. A vertical section from Fair Isle into the German Bight in summer demonstrates high spatial phosphate variability in the water column and in the sediment. Observations on the sediment-water interface fluxes and of concentration distributions in the sediment are very sparse. The results of this high-resolution model allows the calculation of budgets at the sediment-water interface for the whole simulation area. The annual cumulated phosphate flux across the sediment-water interface exhibits strong fluxes concentrated in a narrow band off the continental coast in shallow waters over 40 mmol m -2 yr -1, whereas in the central North Sea fluxes are lower than 30 mmol m -2 yr -1. Simulated annual cycle of fluxes at the sediment-water interface at a position located in the central North Sea showed a phosphate flux shifted by 1 month compared to the organic matter flux, whereas the sulphate flux into the sediment showed an overall time lag of about 5 months.

  8. The role of cornice fall avalanche sedimentation in the valley Longyeardalen, Central Svalbard

    NASA Astrophysics Data System (ADS)

    Eckerstorfer, M.; Christiansen, H. H.; Rubensdotter, L.; Vogel, S.

    2012-12-01

    In arctic and alpine high relief landscapes snow avalanches are traditionally ranked behind rockfall in terms of their significance for mass wasting processes of rock slopes. Cornice fall avalanches are at present the most dominant snow avalanche type at two slope systems, called Nybyen and Larsbreen, in the valley Longyeardalen in Central Svalbard. Both slope systems are situated on NW-facing lee slopes underneath large summit plateau, where cornices form annually, and high frequency and magnitude cornice fall avalanching is observed by daily automatic time-lapse photography. In addition, rock debris sedimentation by these cornice fall avalanches was measured directly in either permanent sediment traps or by snow inventories. The results from a maximum of 7 yr of measurements in a total of 13 catchments show maximum avalanche sedimentation rates ranging from 8.2 to 38.7 kg m-2 at Nybyen and from 0.8 to 55.4 kg m-2 at Larsbreen. Correspondingly, the avalanche fan-surfaces accreted annually in a~maximum range from 3.7 to 13 mm yr-1 at Nybyen and from 0.3 to 21.4 mm yr-1 at Larsbreen. This comparably efficient rock slope mass wasting is due to collapsing cornices producing cornice fall avalanche with high rock debris content throughout the entire winter. The rock debris of different origin stems from the plateau crests, the adjacent free rock face and the transport pathway, accumulating distinct avalanche fans at both slope systems and contributing to the development of a rock glacier at the Larsbreen slope system.

  9. Modeling of suspended sediments in Chesapeake Bay

    NASA Astrophysics Data System (ADS)

    Kim, S.; Harris, C. K.; Cerco, C.

    2011-12-01

    For the Chesapeake Bay, the largest estuary in the United States, four movements have been identified as sediment pathways in which-seaward movement driven by the Susquehanna River at the head, movement from the Main Bay to tributaries, input from the ocean through the entrance of the Bay, and the shoreline erosion. To the management, this poses the source of sediments to the system. The sediment loading sources are identified as above-fall-line watershed loading, non-point source watershed loading, loading from shoreline erosion, and influx from the ocean through the entrance. The sediments introduced from the sources are transported through the water column as well as over the bed. The sediments are either accumulated (deposition) or winnowed from the bed (resuspension). The sediments in an estuary are in principle mixed sediments. Unlike many rivers, cohesive sediments dominate the sediment population. When a model is built to accommodate physical processes, the significance of physico-chemical and biological processes associated with cohesive sediments such as flocculation should be acknowledged. A modeling system is built upon the Chesapeake Bay Program (CBP) Water Quality (WQ) modeling platform. The watershed model, HSPF, provides sediment loading from the watershed to a water quality model, CE-QUAL-ICM, and hydrological forcing to a hydrodynamic model, CH3D. CH3D is also forced by meteorological forcing including surface heat flux and wind stress which separately forces a wave model. The sediment transport module was built into ICM and currently two independent models are included-one is ROMS-CSTM (regional ocean modeling system community sediment transport model) and SEDZLJ. The bottom currents from CH3D and wave forcing are input to a bottom boundary layer (BBL) model through which bottom shear stresses are calculated. Additional loading from shoreline erosion is also fed to the modeling system. Transport in the water column is controlled by the offline information from CH3D to CE-QUAL-ICM. Deposition on the bed is from the settling sediments in the water column. The bed strata are updated based on erosion-deposition processes. The model was calibrated and validated over 7 year time period between 1994 and 2000 using the CBP long term monitoring data. Both interannual and intra-annual signals were captured. Spatially both Estuary turbidity maximum (ETM) zone in the upper Bay and the secondary turbidity maximum (STM) in the lower Bay were reproduced. Surface TSS is correlated to watershed loading. Bottom TSS primarily responds to bottom stress. Upper Bay ETM vary with tidal and event scales. Cross-Bay sediment concentration varies with corresponding bottom stress as well as advection. The model has been integrated to ICM and provides long term sediment management for CBP.

  10. Unexpected spontaneous ignition of Late Glacial sediments from the palaeolake Wukenfurche (NE Germany)

    NASA Astrophysics Data System (ADS)

    Dräger, Nadine; Brademann, Brian; Theuerkauf, Martin; Wulf, Sabine; Tjallingii, Rik; S?owi?ski, Micha?; Schlaak, Norbert; B?aszkiewicz, Miros?aw; Brauer, Achim

    2015-04-01

    A new finely laminated sediment archive has been recovered from the palaeolake Wukenfurche, NE Germany, comprising the last Glacial to Interglacial transition. The site is located within the Eberswalde ice-marginal valley and south of the terminal moraine that was formed during the Pomeranian phase of the Weichselian glaciation. Two sediment cores were obtained from the presently swampy area in July 2014. From these individual profiles a 14.7 m long continuous composite profile has been compiled by correlation of distinct marker layers. Glacial sand deposits covered by basal peat are found at the base of the cores. A visible volcanic ash layer 6 cm above the transition from basal peat into the overlaying finely laminated lake sediments corresponds most likely to the late Allerød Laacher See Tephra (LST). Preliminary counting on core photographs of the 3.5 m thick package of reddish and black alternating laminae above the LST yields a total of ca. 2500 layer couplets. Further micro-facies analyses on large-scale thin sections will be applied to test if these couplets are of annual origin (i.e. varves). Standard preparation for large-scale thin sections involves freeze-drying (for 48 hours) of 10 cm-long sediment slabs stored in aluminum boxes. Immediately after releasing the vacuum of the freeze-dryer chamber we observed an unexpected spontaneous combustion of the sediment from a particular interval of the profile. The exothermic combustion process lasted for approximately 10 to 20 minutes during which temperatures of up to 350°C have been measured with an infrared camera. Preliminary results suggest that oxidation of iron sulfides contributes to the observed reaction. To our knowledge this is the first time that such spontaneous combustion of lake sediments after freeze-drying has been observed. Details of the combustion process and sediment characteristics will be provided. This study is a contribution to the Virtual Institute of Integrated Climate and Landscape Evolution Analysis -ICLEA- of the Helmholtz Association, grant number VH-VI-415.

  11. Rates of sediment supply and sea-level rise in a large coastal lagoon

    USGS Publications Warehouse

    Morton, R.A.; Ward, G.H.; White, W.A.

    2000-01-01

    Laguna Madre, Texas, is 3-7 km wide and more than 190 km long, making it one of the longest lagoons in the world. The lagoon encompasses diverse geologic and climatic regions and it is an efficient sediment trap that accumulates clastic sediments from upland, interior, and oceanic sources. The semi-arid climate and frequent tropical cyclones historically have been responsible for the greatest volume of sediment influx. On an average annual basis, eolian transport, tidal exchange, storm washover, mainland runoff, interior shore erosion, and authigenic mineral production introduce approximately one million m3 of sediments into the lagoon. Analyses of these sediment transport mechanisms and associated line sources and point sources of sediment provide a basis for: (1) estimating the long-term average annual sediment supply to a large lagoon; (2) calculating the average net sedimentation rate; (3) comparing introduced sediment volumes and associated aggradation rates with observed relative sea-level change; and (4) predicting future conditions of the lagoon. This comparison indicates that the historical average annual accumulation rate in Laguna Madre (<1 mm/yr) is substantially less than the historical rate of relative sea-level rise (~4 mm/yr). Lagoon submergence coupled with erosion of the western shore indicates that Laguna Madre is being submerged slowly and migrating westward rather than filling, as some have suggested.

  12. CAPS Annual 2010 Annual Report

    E-print Network

    Banaji,. Murad

    CAPS Annual 2010 1 Annual Report 2010 Centre for Astrophysics and Planetary Science School those with research interests in Astrophysics and Planetary Science, (b) to advance the Frontiers and planetary science research that crosses disciplinary borders, and to construct a larger coherent grouping. 2

  13. Sediment transfer dynamics in the Illgraben

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    Quantification of the volumes of sediment removed by rock-slope failure and debris flows and identification of their coupling and controls are pertinent to understanding mountain basin sediment yield and landscape evolution. We analyzed photogrammetrically-derived datasets of hillslope and channel erosion and deposition along with hydroclimatic variables from the Illgraben, an active debris flow catchment in the Swiss Alps, spanning 1963 - 2010. Two events in the recent history of the catchment make it particularly interesting and challenging to study: a large rock avalanche in 1961, which filled the channel with sediment, and the construction of check dams along the channel in the late 1960s and 1970s. We aimed to (1) identify the nature of hillslope-channel coupling, (2) identify the dominant controls of hillslope sediment production, channel sediment transfer and total sediment yield, (3) observe the response of the channel system to the 1961 rock avalanche and check dam construction, and (4) develop a conceptual model with which to investigate sediment transfer dynamics in various scenarios, including the absence of check dams along the channel. The study captures a multi-decadal period of channel erosion in response to the 1961 rock avalanche, punctuated by shorter cut-and-fill cycles that occur in response to changes in hillslope sediment supply and changes in transport capacity. Hillslopes eroded rapidly at an average rate of 0.34 myr¯ 1, feeding the channel head with sediment. A near doubling of hillslope erosion in the 1980s coincided with a significant increase of air temperature and reduction in snow cover duration and depth, whilst precipitation variables did not change significantly. We find that the main influence of check-dam construction on channel sediment transfer was an initial reduction in sediment transport and a drop in debris flow activity between 1963 and 1986. After 1986 sediment storages in the channel were filled and debris flow activity resumed. During this time hillslope erosion exceeded channel erosion by 0.14myr¯ 1 indicating that hillslopes eroded independently of channel incision. Channel sediment transfer was transport-limited at the scale of the study as suggested by the aggradation of the channel in periods of very high hillslope flux and its apparent relation to variables connected to runoff generation such as precipitation and snowmelt. We have developed a conceptual model of sediment transfer based on our data set with which to investigate sediment transfer dynamics in a probabilistic sense. A stochastic sediment input from the hillslopes is generated from our magnitude-frequency model of landslides. Sediment is fed into a hillslope storage component, where a fraction is redeposited in long-term storage. Sediment in short-term storage is subsequently fed into the channel system and is only removed given a transport event (rainfall or snowmelt) of sufficient magnitude and sufficient available sediment. Transport events are generated stochastically using a weather generator. We calibrate the model with available data. Despite its simplicity the model reproduces the storage and discharge behavior of the channel system observed over the study period and enables us to test the sensitivity of the system to different parameters and system structures.

  14. Global carbon cycles: A coupled atmosphere-ocean-sediment model

    SciTech Connect

    Tromp, T.K.

    1992-01-01

    A simple one-dimensional advective-diffusive ocean model with a polar outcrop is developed and calibrated to fit modern ocean temperature, phosphorus, oxygen, total carbon, and total alkalinity data. The ocean model includes an atmospheric box which predicts atmospheric P[sub CO2] and oxygen concentrations. In addition, a sediment model is designed to reproduce modern sediment profiles of solid organic carbon and calcite, and pore water oxygen, sulfate, carbonate bicarbonate and carbon dioxide. The organic matter sediment model is used to investigate the interplay of sedimentation rate, bioturbation and microbial kinetics on the total rates of organic carbon and phosphorus regeneration and accumulation in marine sediments. This is done for sediments ranging from coastal to deep ocean. The model is sensitive to the organic carbon flux, sedimentation rate, bottom water oxygen concentration, degradation kinetics and bioturbation rate. The type of diagenetic environment and the extent of remineralization is very dependent on these variables which are currently poorly constrained. The carbonate model uses organic carbon, oxygen and sulfate profiles from the organic sediment as input in addition to the total carbon and alkalinity of the overlying water. It predicts the carbonate, bicarbonate and carbon dioxide pore water concentrations and the sedimentary carbonate fraction. The lysocline and carbonate compensation depth are sensitive to the calcite dissolution rate, the organic to inorganic carbon ratio and organic matter degradation. The sediment and ocean models are combined to form an atmosphere-ocean-sediment model which is used to test the hypothesis that decreased polar surface nutrients and carbon is the cause of the 80 ppm reduction in atmospheric P[sub CO2] observed during the last ice age. The coupled model suggests that sediments play an important role in the global carbon budget.

  15. 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 lab with Sedflume, an apparatus for measuring sediment erosion-parameters. In this report, we present results of the characterization of fine-grained sediment erodibility within Capitol Lake. The erodibility data were incorporated into the previously developed hydrodynamic and sediment transport model. Model simulations using the measured erodibility parameters were conducted to provide more robust estimates of the overall magnitudes and spatial patterns of sediment transport resulting from restoration of the Deschutes Estuary.

  16. Comparative assessment of Fontan operation in modifications of atriopulmonary and total cavopulmonary anastomoses 1 This paper was presented at the Ninth Annual Meeting of the EACTS, Paris, September 1995. 1

    Microsoft Academic Search

    Vladimir P. Podzolkov; Sergey B. Zaets; Mikhail R. Chiaureli; Bagrat G. Alekyan; Lidiya M. Zotova; Igor G. Chernikh

    1997-01-01

    Objectives: The optimal technique of the Fontan operation remains disputable. This investigation was aimed at the comparison of atriopulmonary and total cavopulmonary anastomoses. Methods: The results of 81 operations of total cavopulmonary and 69 operations of atriopulmonary anastomosis, performed from 1983 to 1995 were analysed. A control study was carried out 1–10 (3.7+0.2) years after the operation in 80 patients

  17. Glacial marine sedimentation: Paleoclimatic significance

    SciTech Connect

    Anderson, J.B.; Ashley, G.M. (eds.)

    1991-01-01

    This publication resulted from a symposium held during the 1988 Annual Meeting of the Geological Society of America. Many, but not all, contributors to the symposium have papers in this volume. This Special Paper consists of 14 chapters and a Subject/Geographic index. Each chapter has is own list of references. The papers cover a wide range of modem climate/ ocean environments, including papers on glacial marine sediments from Antarctica, the fiords of Alaska, and sediments from the Canadian High Arctic. In addition, three papers discuss [open quote]old[close quotes] glacial marine records (i.e., pre-Tertiary), and one paper discusses the Yakataga Formation of the Gulf of Alaska which is a Miocene-to-late-Pleistocene sequence. The last chapter in the book includes a survey and summary of the evidence for the paleoclimatic significance of glacial marine sediments by the two editors, John Anderson and Gail Ashley. It is worth noting that Anderson and Domack state in the Foreword that there is a considerable variation in terminology; hence they employ a series of definitions which they urge the other authors to employ. They define and explain what they mean by [open quotes]polar ice cap,[close quotes] [open quote]polar tundra (subpolar),[close quotes] and [open quotes]temperate oceanic and boreal[close quotes] in terms of the dominant glacial and glacial marine processes. Although one might quarrel with the terminology, the broad differences between these three glaciological regimes are indeed fundamental and need to be sought in the geological record. The flavor of the volume can be judged by some of the chapter titles. Contributions on Antarctica include a paper by Anderson and other entitled [open quote]Sedimentary facies associated with Antarctica's floating ice masses[close quotes] and a companion paper by Anderson and Domack which deals with the extremely complex glacial marine facies (13 facies are delimited) in McMurdo Sound, Antarctica.

  18. Extraterrestrial 3 He in Paleocene sediments from Shatsky Rise: Constraints on

    E-print Network

    McGee, David

    Extraterrestrial 3 He in Paleocene sediments from Shatsky Rise: Constraints on sedimentation rate extraterrestrial helium Paleocene We attempt to constrain the variability of the flux of extraterrestrial 3 He.98%) is of extraterrestrial origin. The total helium in the sediments can be explained as a binary mixture of terrestrial

  19. EFFECT OF SEDIMENT ORGANIC CARBON ON SURVIVAL OF HYALELLA AZTECA EXPOSED TO DDT AND ENDRIN

    EPA Science Inventory

    Sediment toxicity tests were conducted with the freshwater amphipod Hyalella azteca using sediments ranging in total organic carbon (TOC) concentration from 3 to 11% and spiked with either DDT or endrin. hile the toxicity in the DDT-spiked sediment decreased with increasing TOC c...

  20. Quantification of bioavailable nickel in sediments and toxic thresholds to Hyalella azteca

    Microsoft Academic Search

    U Borgmann; R Néron; W. P Norwood

    2001-01-01

    Bioaccumulation and chronic toxicity of nickel (Ni) to Hyalella azteca in Ni-spiked sediments was strongly affected by the source of sediment used. The total range in LC50s on a sediment concentration basis ranged over 20 fold. Differences in Ni toxicity generally matched differences in Ni bioaccumulation, and toxicity expressed on a body concentration basis varied less than three fold. Body

  1. EFFECTS OF FREEZING ON TOXICITY OF SEDIMENTS CONTAMINATED WITH DDT AND ENDRIN

    EPA Science Inventory

    Two freshwater sediments containing 3 and 11% total organic carbon (TOC) were spiked with DDT and endrin to compare the effects of cold (4C) and frozen (-20C) storage of the sediment on toxicity to the amphipod Hyalella azteca in lO-d tests. oxicity of the DDT-spiked sediment was...

  2. Methylmercury and sulfate-reducing bacteria in mangrove sediments from Jiulong River Estuary, China

    Microsoft Academic Search

    Hao Wu; Zhenhua Ding; Yang Liu; Jinling Liu; Haiyu Yan; Jiayong Pan; Liuqiang Li; Huina Lin; Guanghui Lin; Haoliang Lu

    2011-01-01

    Estuaries are important sites for mercury (Hg) methylation, with sulfate-reducing bacteria (SRB) thought to be the main Hg methylators. Distributions of total mercury (THg) and methylmercury (MeHg) in mangrove sediment and sediment core from Jiulong River Estuary Provincial Mangrove Reserve, China were determined and the possible mechanisms of Hg methylation and their controlling factors in mangrove sediments were investigated. Microbiological

  3. Seston dynamics and tripton sedimentation in the pelagic zone of a shallow eutrophic lake

    Microsoft Academic Search

    Avital Gasith

    1976-01-01

    The transport of organic matter from the water column to the sediment and the relationship between the dynamics of the settleable fraction and that of the total suspended particulate matter were studied in shallow eutrophic Lake Wingra, Wisconsin. Tripton sedimentation was closely related to the dynamics of seston with a lag of 2 to 4 weeks. Sedimentation rate of tripton

  4. Status and trends in suspended-sediment discharges, soil erosion, and conservation tillage in the Maumee River basin--Ohio, Michigan, and Indiana

    USGS Publications Warehouse

    Myers, Donna N.; Metzker, Kevin D.; Davis, Steven

    2000-01-01

    The relation of suspended-sediment discharges to conservation-tillage practices and soil loss were analyzed for the Maumee River Basin in Ohio, Michigan, and Indiana as part of the U.S. Geological Survey?s National Water-Quality Assessment Program. Cropland in the basin is the largest contributor to soil erosion and suspended-sediment discharge to the Maumee River and the river is the largest source of suspended sediments to Lake Erie. Retrospective and recently-collected data from 1970-98 were used to demonstrate that increases in conservation tillage and decreases in soil loss can be related to decreases in suspended-sediment discharge from streams. Average annual water and suspended-sediment budgets computed for the Maumee River Basin and its principal tributaries indicate that soil drainage and runoff potential, stream slope, and agricultural land use are the major human and natural factors related to suspended-sediment discharge. The Tiffin and St. Joseph Rivers drain areas of moderately to somewhat poorly drained soils with moderate runoff potential. Expressed as a percentage of the total for the Maumee River Basin, the St. Joseph and Tiffin Rivers represent 29.0 percent of the basin area, 30.7 percent of the average-annual streamflow, and 9.31 percent of the average annual suspended-sediment discharge. The Auglaize and St. Marys Rivers drain areas of poorly to very poorly drained soils with high runoff potential. Expressed as a percentage of the total for the Maumee River Basin, the Auglaize and St. Marys Rivers represent 48.7 percent of the total basin area, 53.5 percent of the average annual streamflow, and 46.5 percent of the average annual suspended-sediment discharge. Areas of poorly drained soils with high runoff potential appear to be the major source areas of suspended sediment discharge in the Maumee River Basin. Although conservation tillage differed in the degree of use throughout the basin, on aver-age, it was used on 55.4 percent of all crop fields in the Maumee River Basin from 1993-98. Conservation tillage was used at relatively higher rates in areas draining to the lower main stem from Defiance to Waterville, Ohio and at relatively lower rates in the St. Marys and Auglaize River Basins, and in areas draining to the main stem between New Haven, Ind. and Defiance, Ohio. The areas that were identified as the most important sediment-source areas in the basin were characterized by some of the lowest rates of conservation tillage. The increased use of conservation tillage was found to correspond to decreases in suspended-sediment discharge over time at two locations in the Maumee River Basin. A 49.8 percent decrease in suspended-sediment discharge was detected when data from 1970-74 were compared to data from 1996-98 for the Auglaize River near Ft. Jennings, Ohio. A decrease in suspended-sediment discharge of 11.2 percent was detected from 1970?98 for the Maumee River at Waterville, Ohio. No trends in streamflow at either site were detected over the period 1970-98. The lower rate of decline in suspended-sediment discharge for the Maumee River at Waterville, Ohio compared to the Auglaize River near Ft. Jennings, may be due to resuspension and export of stored sediments from drainage ditches, stream channels, and flood plains in the large drainage basin upstream from Waterville. Similar findings by other investigators about the capacity of drainage networks to store sediment are supported by this investigation. These findings go undetected when soil loss estimates are used alone to evaluate the effectiveness of conservation tillage. Water-quality data in combination with soil-loss estimates were needed to draw these conclusions. These findings provide information to farmers and soil conservation agents about the ability of conservation tillage to reduce soil erosion and suspended-sediment discharge from the Maumee River Basin.

  5. Quantifying fluvial sediment transport in a mountain catchment (Schöttlbach, Styria) using sediment impact sensors

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    Sediment transport in river systems, being the output of geomorphic processes in the catchment, is a recurrent problem for geomorphological sediment budget studies, natural hazard assessment and river engineering. Sediment budgets of alpine catchments are likely to be modified by changing total precipitation and the probability of heavy precipitation events in the context of climate change, even if projections of precipitation change for Austria and the entire Alpine region are still very uncertain. Effective sediment management requires profound knowledge on the sediment cascade in the head-waters. However, bedload measurements at alpine rivers or torrents are rare; in Styria, they are altogether missing. Due to a three hour heavy rainfall event on 07-Jul 2011, which caused cata-strophic flooding with massive damage in the city of Oberwölz and its surrounding, we chose the catchment area of the Schöttlbach in the upper Mur river valley in Styria (Austria) as our study area. In the framework of the ClimCatch project, we intend to develop a conceptual model of coupled and decoupled sediment routing to quantify the most prominent sediment fluxes and sediment sinks, combining up-to-date geomorphological and river engineering techniques. Repeated Airborne Laser Scans will provide an overview of ongoing processes, diachronous TLS surveys (cut-and-fill analysis), ground-penetrating radar and 2D-geoelectric surveys should quantity the most important mass fluxes on the slopes and in the channels and derive a quantitative sediment budget, including the volume of temporary sediment stores. Besides quantifying slope processes, sediment sinks and total sediment output, the sediment trans-port in the torrents is of particular interest. We use sediment impact sensors (SIS) which were in-stalled in several river sections in the main stretch of the Schöttlbach and in its tributaries. The SIS mainly consists of two parts connected by a coated cable, the steel shell with the sensor mounted in the riverbed and the logger-case nearby the river. The number of clast impacts is recorded through an acceleration sensor installed underneath a steel plate. This type of sensor was developed by Richardson et al. and later applied e.g. by Raven et al. and Rickenmann & Fritschi. However, this device does not supply volumetric information of sediment flux. For data on sediment volumes we are monitoring the sediment retention dam at the outlet of the Schöttlbach using repeated TLS sur-veys. Our measurements focus on the representative sub-catchments and will deliver values on the in- and output of river sections. Tests and calibration are carried out in an artificial channel at the Water Engineering laboratory of the TU Graz; the sensors are sensitive enough to record impacts of parti-cles > 5 mm. Further calibrations are carried out in the field using mobile basket samplers. The SIS were installed in winter 2012/13. First results allow us to derive the start of sediment transport in dependence of precipitation or water level, respectively. ClimCatch should find out where the sediments of the Schöttlbach catchment actually derive from, which geomorphic processes are the most important in our study area and which catchment areas are significant for the overall sediment output.

  6. Characterization of suspended solids and total phosphorus loadings from small watersheds in Wisconsin

    USGS Publications Warehouse

    Danz, Mari E.; Corsi, Steven R.; Graczyk, David J.; Bannerman, Roger T.

    2010-01-01

    Knowledge of the daily, monthly, and yearly distribution of contaminant loadings and streamflow can be critical for the successful implementation and evaluation of water-quality management practices. Loading data for solids (suspended sediment and total suspended solids) and total phosphorus and streamflow data for 23 watersheds were summarized for four ecoregions of Wisconsin: the Driftless Area Ecoregion, the Northern Lakes and Forests Ecoregion, the North Central Hardwoods Ecoregion, and the Southeastern Wisconsin Till Plains Ecoregion. The Northern Lakes and Forests and the North Central Hardwoods Ecoregions were combined into one region for analysis due to a lack of sufficient data in each region. Urban watersheds, all located in the Southeastern Wisconsin Till Plains, were analyzed separately from rural watersheds as the Rural Southeastern Wisconsin Till Plains region and the Urban Southeastern Wisconsin Till Plains region. Results provide information on the distribution of loadings and streamflow between base flow and stormflow, the timing of loadings and streamflow throughout the year, and information regarding the number of days in which the majority of the annual loading is transported. The average contribution to annual solids loading from stormflow periods for the Driftless Area Ecoregion was 84 percent, the Northern Lakes and Forests/North Central Hardwoods region was 71 percent, the Rural Southeastern Wisconsin Till Plains region was 70 percent, and the Urban Southeastern Wisconsin Till Plains region was 90 percent. The average contributions to annual total phosphorus loading from stormflow periods were 72, 49, 61, and 76 percent for each of the respective regions. The average contributions to annual streamflow from stormflow periods are 20, 23, 31, and 50 percent for each of the respective regions. In all regions, the most substantial loading contributions for solids were in the late winter (February through March), spring (April through May), and early summer (June through July), with fall (October through November) and early winter (December through January) contributing the smallest loadings. The Northern Lakes and Forests/North Central Hardwoods region had some substantial loading in September. There was a similar pattern for total phosphorus loading in all regions, with the pattern somewhat less pronounced in urban watersheds. As with the loading results, average monthly streamflow values were greatest in late winter, spring, and early summer, with the lowest values typically in fall and early winter. Loading contributions were greater from stormflow than from base flow in all instances, except total phosphorus in the Northern Lakes and Forests/North Central Hardwoods region, which had equal or greater base-flow contribution for several months. Base flow constituted a greater percentage of the total streamflow than stormflow in all rural watersheds for all regions. Only a few storms each year dominated the annual loading totals for solids and total phosphorus. When daily loading values were ranked for the year, all regions reached 50 percent of the annual solids loading in the 5 highest loading days and nearly 50 percent of the annual total phosphorus loading in the 14 highest loading days.

  7. Assessment of nutrients, suspended sediment, and pesticides in surface water of the upper Snake River basin, Idaho and western Wyoming, water years 1991-95

    USGS Publications Warehouse

    Clark, Gregory M.

    1997-01-01

    Quality Assessment Program. As part of the investigation, intensive monitoring was conducted during water years 1993 through 1995 to assess surface-water quality in the basin. Sampling and analysis focused on nutrients, suspended sediments, and pesticides because of nationwide interest in these constituents. Concentrations of nutrients and suspended sediment in water samples from 19 sites in the upper Snake River Basin, including nine on the main stem, were assessed. In general, concentrations of nutrients and suspended sediment were smaller in water from the 11 sites upstream from American Falls Reservoir than in water from the 8 sites downstream from the reservoir where effects from land-use activities are most pronounced. Median concentrations of dissolved nitrite plus nitrate as nitrogen at the 19 sites ranged from less than 0.05 to 1.60 milligrams per liter; total phosphorus as phosphorus, less than 0.01 to 0.11 milligrams per liter; and suspended sediment, 4 to 72 milligrams per liter. Concentrations of nutrients and suspended sediment in the main stem of the Snake River, in general, increased downstream. The largest concentrations in the main stem were in the middle reach of the Snake River between Milner Dam and the outlet of the upper Snake River Basin at King Hill. Significant differences (p Nutrient and suspended sediment inputs to the middle Snake reach were from a variety of sources. During water year 1995, springs were the primary source of water and total nitrogen to the river and accounted for 66 and 60 percent of the total input, respectively. Isotope and water-table information indicated that the springs derived most of their nitrogen from agricultural activities along the margins of the Snake River. Aquacultural effluent was a major source of ammonia (82 percent), organic nitrogen (30 percent), and total phosphorus (35 percent). Tributary streams were a major source of organic nitrogen (28 percent) and suspended sediment (58 percent). In proportion to its discharge (less than 1 percent), the Twin Falls sewage-treatment plant was a major source of total phosphorus (13 percent). A comparison of discharge and loading in water year 1995 with estimates of instream transport showed a good correlation (relative difference of less than 15 percent) for discharge, total organic nitrogen, dissolved nitrite plus nitrate, total nitrogen, and total phosphorus. Estimates of dissolved ammonia and suspended sediment loads correlated poorly with instream transport; relative differences were about 79 and 61 percent, respectively. The pesticides EPTC, atrazine, desethylatrazine, metolachlor, and alachlor were the most commonly detected in the upper Snake River Basin and accounted for about 75 percent of all pesticide detections. All pesticides detected were at concentrations less than 1 microgram per liter and below water-quality criteria established by the U.S. Environmental Protection Agency. In samples collected from two small agriculturally dominated tributary basins, the largest number and concentrations of pesticides were detected in May and June following early growing season applications. At one of the sites, the pesticide atrazine and its metabolite desethylatrazine were detected throughout the year. On the basis of 37 samples collected basinwide in May and June 1994, total annual subbasin applications and instantaneous instream fluxes of EPTC and atrazine showed logarithmic relations with coefficients of determination (R2 values) of 0.55 and 0.62, respectively. At the time of sampling, the median daily flux of EPTC was about 0.0001 percent of the annual quantity applied, whereas the median daily flux of atrazine was between 0.001 and 0.01 percent.

  8. Concentrations of DDTs and dieldrin in Long Island Sound sediment.

    PubMed

    Yang, Lijia; Li, Xiqing; Zhang, Pengfei; Melcer, Michael E; Wu, Youxian; Jans, Urs

    2012-03-01

    The concentrations of three frequently detected organochlorine pesticides (OCPs) and one degradation product, p,p'-DDT, p,p'-DDD, dieldrin, and p,p'-DDE were determined in recently collected (2005-2006) and archived (1986-1989) surficial sediments and sediment cores from Long Island Sound (LIS). The concentration of dieldrin ranged from 0.05 to 5.27 ng g(-1) dry weight in the surficial sediments, and from 0.05 to 11.7 ng g(-1) dry weight in the sediment cores. Total DDXs (the sum of p,p'-DDE, p,p'-DDD and p,p'-DDT) concentrations ranged from 1.31 to 33.2 ng g(-1) in surficial sediments and 1.11 to 66.4 ng g(-1) in sediment cores. The results indicate that the three OCPs and DDE were still widely present in LIS surficial sediments two decades after the use of these pesticides in the United States was banned. In addition, the surficial concentrations did not decrease significantly when compared to the concentrations in archived samples collected two decades ago. Sediments in the western part of LIS were more contaminated (with concentrations in some western sites being still above probable effect levels) than those in the eastern part, probably as a result of the net westward sediment transport in LIS. The three OCPs and DDE were detected at all depths (down to ~50 cm) in the sediment cores, and concentration profiles indicated a depositional sedimentary environment with significant sediment mixing. Such mixing may redistribute OCPs deposited earlier (deeper in sediment bed) to the sediment surface and lead to enhanced persistence of OCP concentrations in surficial sediments. PMID:22281775

  9. Varves in lake sediments - a review

    NASA Astrophysics Data System (ADS)

    Zolitschka, Bernd; Francus, Pierre; Ojala, Antti E. K.; Schimmelmann, Arndt

    2015-06-01

    Downcore counting of laminations in varved sediments offers a direct and incremental dating technique for high-resolution climatic and environmental archives with at least annual and sometimes even seasonal resolution. The pioneering definition of varves by De Geer (1912) had been restricted to rhythmically deposited proglacial clays. One century later the meaning of 'varve' has been expanded to include all annually deposited laminae in terrestrial and marine settings. Under favourable basin configurations and environmental conditions, limnic varves are formed due to seasonality of depositional processes from the lake's water column and/or transport from the catchment area. Subsequent to deposition of topmost laminae, the physical preservation of the accumulating varved sequence requires the sustained absence of sediment mixing, for example via wave action or macrobenthic bioturbation. Individual (sub)laminae in varved lake sediments typically express contrasting colours, always differ in terms of their organic, chemical and/or mineralogical compositions, and often also differ with regard to grain-size. Various predominating climatic and depositional conditions may result in clastic, biogenic or endogenic (incl. evaporitic) varved sediments and their mixtures. To reliably establish a varve chronology, the annual character of laminations needs to be determined and verified in a multidisciplinary fashion. Sources and influences of possible errors in varve chronologies are best determined and constrained by repeated varve counts, and by including radioisotopes and correlation with historically documented events. A well-established varve chronology greatly enhances the scientific value of laminated limnic archives by securely anchoring the wealth of multi-proxy palaeoenvironmental information in the form of time-series for multidisciplinary investigations. Applications of varved records are discussed with special reference to advances since the 1980s. These span fields like calibrating radiometric dating methods, reconstructing past changes of the Earth's magnetic field or detecting fluctuations in solar forcing. Once a varve chronology is established it can be applied to precisely date events like volcanic ash layers, earthquakes or human impact, as well as short- and long-term climate (temperature, precipitation, wind, hydroclimatic conditions or flooding) and environmental changes (eutrophication, pollution). Due to their exceptional high temporal resolution and in combination with their robust and accurate "internal" time scale in calendar years, annually laminated sediments can be regarded as one of the most precious environmental archives on the continents. These records are necessary to extend temporally limited instrumental records back in time. As such they have societal relevance with regard to risk assessments related to natural hazards arising from e.g. flooding or volcanic eruptions.

  10. High rates of organic carbon burial in fjord sediments globally

    NASA Astrophysics Data System (ADS)

    Smith, Richard W.; Bianchi, Thomas S.; Allison, Mead; Savage, Candida; Galy, Valier

    2015-06-01

    The deposition and long-term burial of organic carbon in marine sediments has played a key role in controlling atmospheric O2 and CO2 concentrations over the past 500 million years. Marine carbon burial represents the dominant natural mechanism of long-term organic carbon sequestration. Fjords--deep, glacially carved estuaries at high latitudes--have been hypothesized to be hotspots of organic carbon burial, because they receive high rates of organic material fluxes from the watershed. Here we compile organic carbon concentrations from 573 fjord surface sediment samples and 124 sediment cores from nearly all fjord systems globally. We use sediment organic carbon content and sediment delivery rates to calculate rates of organic carbon burial in fjord systems across the globe. We estimate that about 18 Mt of organic carbon are buried in fjord sediments each year, equivalent to 11% of annual marine carbon burial globally. Per unit area, fjord organic carbon burial rates are one hundred times as large as the global ocean average, and fjord sediments contain twice as much organic carbon as biogenous sediments underlying the upwelling regions of the ocean. We conclude that fjords may play an important role in climate regulation on glacial-interglacial timescales.

  11. Reconstructed Sediment Mobilization Processes in a Large Reservoir Using Short Sediment Cores

    NASA Astrophysics Data System (ADS)

    Cockburn, J.; Feist, S.

    2014-12-01

    Williston Reservoir in northern British Columbia (56°10'31"N, 124°06'33") was formed when the W.A.C. Bennett Dam was created in the late 1960s, is the largest inland body of water in BC and facilitates hydroelectric power generation. Annually the reservoir level rises and lowers with the hydroelectric dam operation, and this combined with the inputs from several river systems (Upper Peace, Finlay, Parsnip, and several smaller creeks) renews suspended sediment sources. Several short-cores retrieved from shallow bays of the Finlay Basin reveal near-annual sedimentary units and distinct patterns related to both hydroclimate variability and the degree to which the reservoir lowered in a particular year. Thin section and sedimentology from short-cores collected in three bays are used to evaluate sediment mobilization processes. The primary sediment sources in each core location is linked to physical inputs from rivers draining into the bays, aeolian contributions, and reworked shoreline deposits as water levels fluctuate. Despite uniform water level lowering across the reservoir, sediment sequences differed at each site, reflecting the local stream inputs. However, distinct organic-rich units, facilitated correlation across the sites. Notable differences in particle size distributions from each core points to important aeolian derived sediment sources. Using these sedimentary records, we can evaluate the processes that contribute to sediment deposition in the basin. This work will contribute to decisions regarding reservoir water levels to reduce adverse impacts on health, economic activities and recreation in the communities along the shores of the reservoir.

  12. Crenarchaeota in Lake Michigan sediment.

    PubMed Central

    MacGregor, B J; Moser, D P; Alm, E W; Nealson, K H; Stahl, D A

    1997-01-01

    RNA from Lake Michigan sediment was hybridized with a DNA probe for archaeal 16S rRNA. There was a peak of archaeal rRNA abundance in the oxic zone and another immediately below it. Six contributing species were identified by PCR amplification of extracted DNA with primers specific for archaeal rDNA: two related to Methanosarcina acetivorans and four related to marine crenarchaeotal sequences. rRNA quantification using a DNA probe specific for this crenarchaeotal assemblage showed it is most abundant in the oxic zone, where it accounts for about 10% of total archaeal rRNA. PMID:9055434

  13. 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.

  14. Evaluation of radiological hazards in the sediments of Ogun river, South-Western Nigeria

    NASA Astrophysics Data System (ADS)

    Jibiri, N. N.; Okeyode, I. C.

    2012-02-01

    The concentrations of natural radionuclides in the sediments of Ogun river in South Western Nigeria have been measured and determined using gamma-ray spectrometry. The mean activity concentrations of 40K, 226Ra, and 232Th at different locations along the course of the river were found to vary from 370.99±19.26 Bq/kg (at Olopade) to 608.02±24.66 Bq/kg (at Owere), 5.57±2.34 (at Ekerin) to 20.40±4.52 Bq/kg (at Sokori) and 5.04±2.24 Bq/kg (at mile 12-Maidan) to 23.10±4.81 Bq/kg (at Sokori) respectively. The overall calculated mean of the total indoor absorbed dose rates was 64.46±9.16 nGy/h with corresponding annual indoor effective dose of 0.32±0.05 mSv/y. Radium equivalent activity (Ra eq), external hazard index ( Hex), internal hazard index ( Hin) and representative gamma index ( I?r) were calculated in order to assess the radiation hazards associated with the use of these sediments in the construction of dwellings. The overall estimated values for the radium equivalent activity, external hazard index, internal hazard index and the representative gamma index were 67.96±10.74 Bq/kg, 0.18±0.03, 0.22±0.05 and 0.54±0.08, respectively. These values obtained for the river sediments were less than the recommended safe and criterion limits by UNSCEAR and also, they compared well with the values from other countries of normal radiation areas. It suffices to say therefore that sediments from Ogun river are safe and can be used for construction of buildings without undue radiological health concerns. Results of the study could serve as an important baseline radiometric data for future epidemiological studies and monitoring initiatives in the study area.

  15. Sedimentation Counting and Morphology of Mycoplasma

    PubMed Central

    Clark, Harold W.

    1965-01-01

    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 OsO4 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 m?) containing a limited deoxyribonucleic acid genetic coding molecule (approximately 4 × 106). Images PMID:5321487

  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. Large freshwater and sediment impoundments between the Mississippi River and the Louisiana coastline

    NASA Astrophysics Data System (ADS)

    Andersen, G. R.; Hall, B.; Aieta, E. M.

    2015-03-01

    An innovative system-level sediment and freshwater management plan is proposed for the coastal regions of Louisiana, USA. It involves the construction of large sediment and freshwater impoundments between the river and coastline fed periodically through large spillway structures during the rising hydrograph of the river when the highest concentration of sediment is in the water column. Sediment directing and trapping technologies are proposed for the river channel and spillways to capture the coarser-grained sediments. The embankments can be constructed from dredging and then enlarged by land-based harvesting of coarse-grained sediments from the traps. These impoundments will permit the continuous introduction of freshwater and finer-grained sediments to coastal marshlands for vegetation, land augmentation, protection from storm surges and salt water intrusion, while removing large amounts of sand from the river and decreasing annual maintenance dredging costs.

  18. Recent sedimentation patterns within the central Atchafalaya Basin, Louisiana

    USGS Publications Warehouse

    Hupp, C.R.; Demas, C.R.; Kroes, D.E.; Day, R.H.; Doyle, T.W.

    2008-01-01

    Sediment deposition and storage are important functions of forested bottomlands, yet documentation and interpretation of sedimentation processes in these systems remain incomplete. Our study was located in the central Atchafalaya Basin, Louisiana, a distributary of the Mississippi River and contains the largest contiguously forested riparian wetland in North America, which suffers from high sedimentation in some areas and hypoxia in others. We established 20 floodplain transects reflecting the distribution of depositional environments within the central Basin and monitored general and local sediment deposition patterns over a three-year period (2000-2003). Deposition rate, sediment texture, bulk density, and loss on ignition (LOI, percent organic material) were determined near or just above artificial markers (clay pads) located at each station per transect. Transect mean sedimentation rates ranged from about 2 to 42 mm/yr, mean percent organic material ranged from about 7% to 28%, mean percent sand (> 63 ??) ranged from about 5% to 44%, and bulk density varied from about 0.4 to 1.3. The sites were categorized into five statistically different clusters based on sedimentation rate; most of these could be characterized by a suite of parameters that included hydroperiod, source(s) of sediment-laden water, hydraulic connectivity, flow stagnation, and local geomorphic setting along transect (levee versus backswamp), which lead to distinct spatial sedimentation patterns. Sites with low elevation (long hydroperiod), high hydraulic connectivity to multiple sources of sediment-laden water, and hydraulic damming (flow stagnation) featured the highest amounts of sediment trapping; the converse in any of these factors typically diminished sediment trapping. Based on aerial extent of clusters, the study area potentially traps 6,720,000 Mg of sediment annually, of which, 820,000 Mg represent organic materials. Thus, the Atchafalaya Basin plays a substantial role in lowland sediment (and associated contaminant) storage, including the sequestration of carbon. Findings on local sedimentation patterns may aid in management of flow to control sediment deposition and reduce hypoxia. ?? 2008, The Society of Wetland Scientists.

  19. Characteristics of suspended sediment in the San Juan River near Bluff, Utah

    USGS Publications Warehouse

    Thompson, K.R.; Mundorff, J.C.

    1982-01-01

    Fluvial-sediment data were collected for the San Juan River near Bluff beginning in 1914 and terminating in 1980. A double-mass curve showed a change in relationship between annual suspended-sediment discharge and annual stream discharge between the water years 1941-44 and 73. Possible causes for these changes in laboratory procedures, and unusually large runoff that occurred in 1941 and 1972. An unknown or unidentified factor may also be involved. The actual reason for this change in relationship may never be fully understood. Navajo Dam apparently has had no significant effect on fluvial sediment at the sampling site. Mean annual suspended sediment discharge in the San Juan River near Bluff was about 25,410,000 tons ranging from 3,234,000 tons in 1978 to 112,400,000 tons in 1941. The use of annual stream discharge to predict annual suspended-sediment discharge at the site will produce poor results because of size and diversity of the basin and the quality of records available. A positive correlation exists between sand concentration and stream discharge at this site, however, considerable variability is evident. This relationship does not exist when stream discharge exceeds 6,000 cubic feet per second. It is recommended that if collection of suspended-sediment records be resumed in this reach of the river an alternative sampling site should be selected and the use of pumping samplers considered because of the remoteness of the area. (USGS)

  20. Time-integrated sampling of fluvial suspended sediment: a simple methodology for small catchments

    NASA Astrophysics Data System (ADS)

    Phillips, J. M.; Russell, M. A.; Walling, D. E.

    2000-10-01

    Fine-grained (<62·5 µm) suspended sediment transport is a key component of the geochemical flux in most fluvial systems. The highly episodic nature of suspended sediment transport imposes a significant constraint on the design of sampling strategies aimed at characterizing the biogeochemical properties of such sediment. A simple sediment sampler, utilizing ambient flow to induce sedimentation by settling, is described. The sampler can be deployed unattended in small streams to collect time-integrated suspended sediment samples. In laboratory tests involving chemically dispersed sediment, the sampler collected a maximum of 71% of the input sample mass. However, under natural conditions, the existence of composite particles or flocs can be expected to increase significantly the trapping efficiency. Field trials confirmed that the particle size composition and total carbon content of the sediment collected by the sampler were representative statistically of the ambient suspended sediment.

  1. Rare earth elements in intertidal sediments of Bohai Bay, China: concentration, fractionation and the influence of sediment texture.

    PubMed

    Zhang, Yong; Gao, Xuelu; Arthur Chen, Chen-Tung

    2014-07-01

    Surface sediments from intertidal Bohai Bay were assessed using a four-step sequential extraction procedure to determine their concentrations of rare earth elements (REEs) and the chemical forms in which those elements were present. The normalized ratios La/Gd and La/Yb showed that LREE contents were not significantly higher than the middle REEs or HREE contents. A negative Ce anomaly and positive Eu were observed in sand and silty sand sediments, whereas no significant Ce or Eu anomaly was found in clayey silt sediments. Residual fraction of REEs accounted for the majority of their total concentrations. Middle REEs were more easily leached than other REEs, especially in clayey silt sediment. REEs contents in the surface sediment from the intertidal Bohai Sea were consistent with data from the upper continental crust and China shallow sea sediments, indicating that they were generally unaffected by heavily anthropogenic effects from adjacent areas. PMID:24793516

  2. Trends in Streamflow and Nutrient and Suspended-Sediment Concentrations and Loads in the Upper Mississippi, Ohio, Red, and Great Lakes River Basins, 1975-2004

    USGS Publications Warehouse

    Lorenz, David L.; Robertson, Dale M.; Hall, David W.; Saad, David A.

    2009-01-01

    Many actions have been taken to reduce nutrient and suspended-sediment concentrations and the amount of nutrients and sediment transported in streams as a result of the Clean Water Act and subsequent regulations. This report assesses how nutrient and suspended-sediment concentrations and loads in selected streams have changed during recent years to determine if these actions have been successful. Flow-adjusted and overall trends in concentrations and trends in loads from 1993 to 2004 were computed for total nitrogen, dissolved ammonia, total organic nitrogen plus ammonia, dissolved nitrite plus nitrate, total phosphorus, dissolved phosphorus, total suspended material (total suspended solids or suspended sediment), and total suspended sediment for 49 sites in the Upper Mississippi, Ohio, Red, and Great Lakes Basins. Changes in total nitrogen, total phosphorus, and total suspended-material loads were examined from 1975 to 2003 at six sites to provide a longer term context for the data examined from 1993 to 2004. Flow-adjusted trends in total nitrogen concentrations at 19 of 24 sites showed tendency toward increasing concentrations, and overall trends in total nitrogen concentrations at 16 of the 24 sites showed a general tendency toward increasing concentrations. The trends in these flow-adjusted total nitrogen concentrations are related to the changes in fertilizer nitrogen applications. Flow-adjusted trends in dissolved ammonia concentrations from 1993 to 2004 showed a widespread tendency toward decreasing concentrations. The widespread, downward trends in dissolved ammonia concentrations indicate that some of the ammonia reduction goals of the Clean Water Act are being met. Flow-adjusted and overall trends in total organic plus ammonia nitrogen concentrations from 1993 to 2004 did not show a distinct spatial pattern. Flow-adjusted and overall trends in dissolved nitrite plus nitrate concentrations from 1993 to 2004 also did not show a distinct spatial pattern. Flow-adjusted trends in total phosphorus concentrations were upward at 24 of 40 sites. Overall trends in total phosphorus concentrations were mixed and showed no spatial pattern. Flow-adjusted and overall trends in dissolved phosphorus concentrations were consistently downward at all of the sites in the eastern part of the basins studied. The reduction in phosphorus fertilizer use and manure production east of the Mississippi River could explain most of the observed trends in dissolved phosphorus. Flow-adjusted trends in total suspended-material concentrations showed distinct spatial patterns of increasing tendencies throughout the western part of the basins studied and in Illinois and decreasing concentrations throughout most of Wisconsin, Iowa, and in the eastern part of the basins studied. Flow-adjusted trends in total phosphorus were strongly related to the flow-adjusted trends in suspended materials. The trends in the flow-adjusted suspended-sediment concentrations from 1993 to 2004 resembled those for suspended materials. The long-term, nonmonotonic trends in total nitrogen, total phosphorus, and suspended-material loads for 1975 to 2003 were described by local regression, LOESS, smoothing for six sites. The statistical significance of those trends cannot be determined; however, the long-term changes found for annual streamflow and load data indicate that the monotonic trends from 1993 to 2004 should not be extrapolated backward in time.

  3. Estimating Total Suspended Sediments in Tropical Open Bay Conditions

    E-print Network

    Gilbes, Fernando

    at approximately 1 meter deep Concentrations of TSS (mg/l) was determined with the standard weight difference Rainy 6 0 Research Cruises Details #12;MODIS images NASA Product (LAADS Web) File name: MOD02QKM · Band- Dark Subtract User Value #12;Complementary equation used to generate TSS products TSS vs. Rrs 645 nm

  4. Estimating Total Suspended Sediment Yield With Probability Sampling

    Microsoft Academic Search

    Robert B. Thomas

    1985-01-01

    ment record. The tested combinations of estimation technique and data collection method ranged from 70% below to 40% above the true value. Most of the estimates were less than 60% of the correct value. The variance of the estimators tended to increase as the accuracy improved, thus cancelling the benefits, and no approach emerged as the ideal choice for all

  5. Eutrophication and sedimentation patterns in complete exploitation of water resources scenarios: an example from Northwestern semi-arid Mexico.

    PubMed

    Sánchez-Carrillo, Salvador; Alatorre, Luis C; Sánchez-Andrés, Raquel; Garatuza-Payán, Jaime

    2007-09-01

    Water requirements to supply human needs lead water stakeholders to store more water during surplus periods to fulfil the demand during--not only--scarcity periods. At the reservoirs, mostly those in semi-arid regions, water level then fluctuates extremely between rises and downward during one single year. Besides of water management implications, changes on physical, chemical and biological dynamics of these drawdown and refilling are little known yet. This paper shows the results, throughout a year, on solids, nutrients (N and P), chlorophyll-a, and sedimentation changes on the dynamics, when the former policy was applied in a reservoir from the semi-arid Northwestern Mexico. Water level sinusoidal trend impinged changes on thermal stratification and mixing, modifying nutrient cycling and primary producer responses. According to nitrogen and phosphorus concentration as well as chlorophyll-a, reservoir was mesotrophic, becoming hypertrophic during drawdown. Nutrient concentrations were high (1.22 +/- 0.70 and 0.14 +/- 0.12 mg P l(-1)), increasing phosphorus and lowering N:P significantly throughout the study period, although no intensive agricultural, no urban development, neither industrial activities take place in the watershed. This suggests nutrient recycling complex mechanisms, including nutrient release from the sediment-water interface as the main nutrient pathway when shallowness, at the same time as mineralization, increases. Outflows controlled nitrogen and phosphorus availability on the ecosystem while organic matter depended on river inflows. As on other subtropical aquatic ecosystems, nitrogen limited primary productivity (Spearman correlation R = 0.75) but chlorophyll-a seasonal pattern showed an irregular trend, prompting other no-nutrient related limitants. Shallowness induced a homogeneous temporal pattern on water quality. This observed temporal variability was mainly explained statistically by changes on solids (mineral and organic), chlorophyll-a and flows (62.3%). Annual sedimentation rates of total solids ranged from 11.73 to 16.29 kg m(-2) year(-1) with organic matter comprising around 30%. N:P ratio on sedimentation rates were as high as could be expected in a resuspension dominated ecosystem, and spatially inverse related with N:P ratio on bottom sediments. Distance from river inlet into the reservoir reveals a marked spatial heterogeneity on solid and nitrogen sedimentation, showing the system dependence on river inflows and supporting resuspension as the main phosphorus pathway. Accretion rates (2.19 +/- 0.40 cm year(-1)) were not related to hydrological variability but decreased with the distance to the river input. Total sediment accumulation (9,895 tons km(-2) year(-1)) denotes siltation as other serious environmental problem in reservoirs but possibly not related with operational procedures. PMID:17171240

  6. First Assessment of the Importance of Land-Derived vs. Marine Organic Matter in Surface Sediments From Hudson Bay

    NASA Astrophysics Data System (ADS)

    Kuzyk, Z. A.; MacDonald, R. W.; Goni, M. A.; Stern, G.

    2006-12-01

    Hudson Bay is an inland sea that receives a large portion of Canada's freshwater runoff, more than the combined discharge of the Mackenzie and St. Lawrence Rivers. It represents a southern extension of Arctic Ocean water and is one of the southern-most seas having a complete cryogenic cycle. The effect of climate change on this system is becoming an urgent concern, with changes in river discharge, ice conditions, and ice-dependent components of the ecosystem already documented and further dramatic changes projected by the end of this century. Integrated studies to address major shortfalls in our knowledge of the Bay are just getting underway and hopefully will be continued during IPY. Here, we describe elemental, stable isotopic compositions, and CuO oxidation products from surface sediments distributed throughout Hudson Bay and from various source materials (river suspended sediments). Our results suggest that despite the extremely large (65-80 cm) annual yield of river water delivered to the Bay, surface sediments in most areas are dominated by marine organic carbon. We reach this conclusion based on relatively enriched d13C values (- 21.6 per mil) and d15N values (8.0 per mil), low organic carbon:total nitrogen ratios (8.8), and low organic- carbon normalized yields of lignin phenols (1.8 mg/ 100 mg OC) in the majority of surface sediment samples. Terrestrial carbon varies regionally in its elemental/isotopic composition and augments the marine carbon to a varying degree in different regions of the Bay. In most locations, we estimate that terrestrial organic carbon contributes only 15-25 per cent of the total carbon in the surface sediments. However, we have yet to account for inputs of old carbon (e.g. kerogen), devoid of recognizable biochemicals, exported into the Bay by erosion of sedimentary rocks. An exception to the general pattern is the relatively coarse-grained coastal sediments of the southwestern part of the Bay (off the Hudson Bay Lowlands), where the sediment organic carbon consists of more than 50 per cent terrestrial organic carbon and contains relatively large quantities (16 mg/ 100 mg OC) of relatively undegraded lignin products.

  7. Particle flux, and composition of sedimenting matter, in the Greenland Sea

    NASA Astrophysics Data System (ADS)

    Bauerfeind, E.; Bodungen, B. V.; Arndt, K.; Koeve, W.

    1994-12-01

    Vertical flux of particulate material was recorded with moored sediment traps during 1988/1989 in the Greenland Sea at 72°N, 10°W. This region exhibits pronounced seasonal variability in ice cover. Annual fluxes at 500 m water depth were 22. 79, 8.55, 2.39, 3.81 and 0.51 g m -2 for total flux (dry weight), carbonate particulate biogenic silicate, particulate organic carbon and nitrogen, respectively. Fluxes increased in April, maximum rates of all compounds occurred in May-June, and consistently high total flux rates of around 100 mg m -2d -1 prevailed the summer. The increasing flux of biogenic particles measured in April is indicative of an early onset of algal growth in spring. Small pennate diatoms dominated in the trap collections during April, and were still numerous during the high flux period when Thalassiosira species were the most abundant diatoms. During May-June, up to 22% of the Thalassiosira cells collected were viable-looking cells. The faecal pellet flux increased after the May-June event. Therefore we conclude that the diatoms settled as phytodetritus, most likely in rapidly sinking aggregates. From seasonal nutrient profiles it is concluded that diatoms contribute 25% to new production during spring and 50% on an annual basis. More than 50% of newly produced silicate particles are dissolved above the 500 m horizon. High new production during spring does not lead to a pronounced sedimentation pulse of organic matter during spring but elevated vertical export is observed during the entire growth period.

  8. A varved lake sediment record from Finland: between the North Atlantic Oscillation and Siberian High Pressure Cell

    NASA Astrophysics Data System (ADS)

    Saarni, Saija; Saarinen, Timo

    2015-04-01

    Varved lake sediments are widely used for paleoclimatological and paleoenvironmental studies. The advantages of such records are precise time control, which enables high resolution studies of even seasonal scale, and the length of the records extending potentially beyond thousands of years. The clastic organic varved sediments from a small boreal Lake Kalliojärvi (area 0.15 km2, maximum depth 12 m) in Central Finland, record environmental change and snow accumulation history for more than two thousand years. The high quality sediments of the Lake Kalliojärvi are laminated until the present day and reflect the annual circulation of boreal zone. A single varve year consists of two laminae that are composed of i) minerogenic clasts and ii) amorphous organic matter and microfossils. Total varve thickness was measured, and the accumulation of minerogenic and organic matter were analyzed using digital image analysis. The major element composition of the lake sediments was also determined using micro X-ray fluorescence (µ-XRF). The clastic laminae are interpreted as a proxy for catchment erosion, reflecting spring floods triggered by snow melt. Qualitative comparison of minerogenic matter accumulation and reconstructed North Atlantic Oscillation (NAO) phases reveal correspondence between the two records. Positive NAO conditions occur simultaneously with increased minerogenic lamina thicknesses which suggest that the changes in snow accumulation are induced by NAO. However, there are indications that the strong Siberian High Pressure Cell (SHPC) prevailing on eastern Scandinavia may be important for Scandinavian climate via blocking the westerly winds. Strong SHCP potentially leads to colder winter temperatures in Finland and increased ice formation. Stronger and prolonged ice cover in lake environments cause prolonged water column stratification and increased oxygen deficiency which is related to an increased Fe/Mn ratio. This study discusses the importance of NAO and SHPC for winter climate in Fennoscandia and evaluates the usability of the lake sediment Fe/Mn ratio as a proxy for strengthened Siberian High Pressure Cell.

  9. Influence of large wood on channel morphology and sediment storage in headwater mountain streams, Fraser Experimental Forest, Colorado

    NASA Astrophysics Data System (ADS)

    Ryan, Sandra E.; Bishop, Erica L.; Daniels, J. Michael

    2014-07-01

    Large fallen wood can have a significant impact on channel form and process in forested mountain streams. In this study, four small channels on the Fraser Experimental Forest near Fraser, Colorado, USA, were surveyed for channel geometries and large wood loading, including the size, source, and characteristics of individual pieces. The study is part of a larger effort to understand the impact of mountain pine beetle infestation on a suite of watershed properties. Here, we present baseline data collected at the onset of widespread tree mortality. Channels range from 1.5 to 2 m in width, with slopes ranging from 3 to > 10%. Median (D50) streambed particle sizes range from gravel to very coarse gravel. Channels are characterized as cascade, step-pool, and plane bed over varying scales. Large wood loads ranged from about 0.4 to 1.0 piece per meter length of channel, which is comparable to values reported for other Colorado sites. Much of the wood showed indications of being in place for long periods of time (decayed/rotten, broken into ramps, and partially buried in beds and banks). Nearly all surveyed reaches contained steps formed from small boulders and/or logs. Significant portions of the elevation drop in some of the reaches were made up by log steps, though the percentages varied (0 to 60%). Individual log steps trap a portion of the coarse sediment moved as bedload, forming wedge-shaped accumulations upstream of the logs. The particle size distributions for measured bedload and step accumulations largely overlapped, but more so for the coarse ends of the distributions, suggesting a trapping inefficiency for the finer component of bedload. Estimates of the total volume of sediment stored behind log steps were approximately an order of magnitude greater than the mean sediment volume exported on an annual basis, as determined from measured accumulations in weir ponds. The particle size distribution of sediment in the ponds - ranging from sand to medium gravel - is considerably finer than sediment stored in steps. The series of comparisons between storage volumes, particle size distributions, and sediment export suggests that log steps effectively trap coarse sediment moved in these small streams and act as a series of check dams that inhibit channel erosion, but may be less effective at trapping finer sediment (sand and small gravel).

  10. Risk of Gastrointestinal Disease Associated with Exposure to Pathogens in the Sediments of the Lower Passaic River?

    PubMed Central

    Donovan, E. P.; Staskal, D. F.; Unice, K. M.; Roberts, J. D.; Haws, L. C.; Finley, B. L.; Harris, M. A.

    2008-01-01

    High levels of pathogenic microorganisms have been documented previously in waters of the Lower Passaic River in northern New Jersey. The purpose of this study was to characterize the microbial contamination of river sediments near combined sewer overflows (CSOs), a known source of pathogens. Concentrations of fecal coliform, total coliform, fecal Streptococcus, fecal Enterococcus, Pseudomonas aeruginosa, Staphylococcus aureus, Giardia lamblia, and Cryptosporidium parvum organisms were measured in 16 samples from three mudflat locations along the Lower Passaic River, as well as from an upstream location. Selected samples were also analyzed for antibiotic resistance. All of the samples contained high concentrations of total coliform, fecal coliform, fecal Streptococcus, and fecal Enterococcus organisms. Analysis of isolates of Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli from several samples indicated that each strain was resistant to at least one antibiotic typically used in clinical settings. Eight of 16 samples contained Giardia, and one sample contained Cryptosporidium. With these sampling data, a quantitative microbial risk assessment was conducted to evaluate the probability of infection or illness resulting from incidental ingestion of contaminated sediments over a 1-year period. Three potential exposure scenarios were considered: visitor, recreator, and homeless person. Single-event risk was first evaluated for the three individual exposure scenarios; overall risk was then determined over a 1-year period using Monte Carlo techniques to characterize uncertainty. For fecal Streptococcus and Enterococcus, annualized risk estimates for gastrointestinal illness ranged from approximately 0.42 to 0.53 for recreators, 0.07 to 0.10 for visitors, and 0.62 to 0.72 for homeless individuals across the three sampling locations. Annualized risk of Giardia infection ranged from 0.14 to 0.64 for recreators, 0.01 to 0.1 for visitors, and 0.30 to 0.87 for homeless individuals, across all locations where detected. Cryptosporidium was detected at one location, and the corresponding annualized risk of infection was 0.32, 0.05, and 0.51 for recreators, visitors, and homeless individuals, respectively. This risk assessment suggests that pathogen-contaminated sediments near areas of CSO discharge in the Lower Passaic River could pose a health risk to individuals coming into contact with sediments in the mudflat areas. PMID:18156335

  11. New strategies for upscaling high-resolution flow and overbank sedimentation models to quantify floodplain sediment storage at the catchment scale

    NASA Astrophysics Data System (ADS)

    Nicholas, A. P.; Walling, D. E.; Sweet, R. J.; Fang, X.

    2006-10-01

    SummaryQuantitative models of catchment scale floodplain sediment storage must balance competing demands. For example, such approaches must incorporate a physically-based representation of controls on overbank sedimentation rates at the reach scale, but should also be computationally efficient so that catchment scale analysis remains a realistic goal. This paper reports the development of a novel nested modelling strategy that combines a high-resolution hydraulic model based on the shallow water form of the Navier-Stokes equations, with a reduced complexity overbank sedimentation model and coarse-resolution catchment sediment budget model. The approach is implemented within a Monte-Carlo framework to allow an assessment of uncertainty in the parameterisation of overbank sedimentation processes, and to derive uncertainty-bounded estimates of floodplain sedimentation rates over a range of spatial scales. This strategy is applied to a 26 km reach of the River Culm, Devon, UK. The relative performance of a wide range of model structures is evaluated by comparing model predictions with estimates of actual mean annual sedimentation rates derived by analysis of the caesium-137 content of floodplain sediment cores at 20 locations within each of eight study sites distributed throughout the catchment. The results of the current model application demonstrate the potential of the nested modelling strategy as a means of upscaling physically-based flow and sediment transport codes. Furthermore, the novel reduced-complexity overbank sedimentation model presented here is shown to provide a means of simulating complex patterns of suspended sediment transport and deposition, while reducing computing costs by 2-3 orders of magnitude compared with conventional high-resolution advection-diffusion codes. Uncertainty-bounded estimates of floodplain sediment storage for the River Culm confirm that floodplain sedimentation represents a primary component of the fine sediment budget of lowland catchments. Consequently, the modelling strategies developed here may also be of considerable value in attempts to quantify the fate of sediment-associated nutrients and contaminants at the basin scale.

  12. Toxicity and Geochemistry of Missouri Cave Stream Sediments

    NASA Astrophysics Data System (ADS)

    Lawler, C. A.; Besser, J.; Wicks, C. M.

    2005-05-01

    Water and sediment quality are among the most important variables affecting the survival of stygobites. In Tumbling Creek Cave, Taney County Missouri the population of the endangered cave snail, Antrobia culveri, has declined significantly over the past decade. The cause of the population decline is unknown but could be related to the quality of streambed sediment in which the cave snail lives. The objective of this study was to determine the toxicity and concentrations of heavy metals in the sediment of Tumbling Creek Cave and five other caves in Missouri. These sediments were analyzed to assess possible point sources from within the recharge areas of the caves and to provide baseline geochemical data to which Tumbling Creek Cave sediments could be compared. Standard sediment toxicity tests and ICP-MS analysis for heavy metals were conducted. Survival and reproduction of the amphipod, Hyalella azteca, did not differ significantly between cave sediments and a control sediment. However the growth of amphipods differed significantly among sites and was significantly reduced in sediments from Tumbling Creek Cave relative to controls. Concentrations of several metals in sediments differed substantially among locations, with elevated levels of zinc and copper occurring in Tumbling Creek Cave. However, none of the measured metal concentrations exceeded sediment quality guidelines derived to predict probable effects on benthic organisms and correlations between sediment metal concentrations and toxicity endpoints were generally weak. While elevated metal levels may play a part in the cave snail's decline, other factors may be of equal or greater importance. Ongoing analyses of persistent organic contaminants and total organic carbon in cave sediments, along with continued water quality monitoring, may provide data that will allow us to better understand this complicated problem.

  13. Combine the soil water assessment tool (SWAT) with sediment geochemistry to evaluate diffuse heavy metal loadings at watershed scale.

    PubMed

    Jiao, Wei; Ouyang, Wei; Hao, Fanghua; Huang, Haobo; Shan, Yushu; Geng, Xiaojun

    2014-09-15

    Assessing the diffuse pollutant loadings at watershed scale has become increasingly important when formulating effective watershed water management strategies, but the process was seldom achieved for heavy metals. In this study, the overall temporal-spatial variability of particulate Pb, Cu, Cr and Ni losses within an agricultural watershed was quantitatively evaluated by combining SWAT with sediment geochemistry. Results showed that the watershed particulate heavy metal loadings displayed strong variability in the simulation period 1981-2010, with an obvious increasing trend in recent years. The simulated annual average loadings were 20.21 g/ha, 21.75 g/ha, 47.35 g/ha and 21.27 g/ha for Pb, Cu, Cr and Ni, respectively. By comparison, these annual average values generally matched the estimated particulate heavy metal loadings at field scale. With spatial interpolation of field loadings, it was found that the diffuse heavy metal pollution mainly came from the sub-basins dominated with cultivated lands, accounting for over 70% of total watershed loadings. The watershed distribution of particulate heavy metal losses was very similar to that of soil loss but contrary to that of heavy metal concentrations in soil, highlighting the important role of sediment yield in controlling the diffuse heavy metal loadings. PMID:25169808

  14. ANNUAL REPORT 2002 57 Annual Financial Statements

    E-print Network

    Hickman, Mark

    ANNUAL REPORT 2002 57 Annual Financial Statements University Annual Financial Statements #12 and reporting of financial performance and position on a historical cost basis adjusted by the revaluation are recognised in the Statement of Financial Position. #12;ANNUAL REPORT 2002 59 Annual Financial Statements

  15. TOTAL DPS NYPD TOTAL DPS NYPD

    E-print Network

    Johnson Jr.,, Ray

    NYPD *Non DPS Section TOTAL Murder/Non-Negligent Manslaughter 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 TOTAL DPS NYPD *Non DPS TOTAL Murder/Non-Negligent Manslaughter 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 *Non DPS TOTAL TOTAL DPS NYPD *Non DPS TOTAL Murder/Non-Negligent Manslaughter 0 0 0 0 0 0 0 0 0 0 0 0

  16. Simultaneous determination of mercury and organic carbon in sediment and soils using a direct mercury analyzer based on thermal decomposition-atomic absorption spectrophotometry.

    PubMed

    Chen, Jingjing; Chakravarty, Pragya; Davidson, Gregg R; Wren, Daniel G; Locke, Martin A; Zhou, Ying; Brown, Garry; Cizdziel, James V

    2015-04-29

    The purpose of this work was to study the feasibility of using a direct mercury analyzer (DMA) to simultaneously determine mercury (Hg) and organic matter content in sediment and soils. Organic carbon was estimated by re-weighing the sample boats post analysis to obtain loss-on-ignition (LOI) data. The DMA-LOI results were statistically similar (p<0.05) to the conventional muffle furnace approach. A regression equation was developed to convert DMA-LOI data to total organic carbon (TOC), which varied between 0.2% and 13.0%. Thus, mercury analyzers based on combustion can provide accurate estimates of organic carbon content in non-calcareous sediment and soils; however, weight gain from moisture (post-analysis), measurement uncertainty, and sample representativeness should all be taken into account. Sediment cores from seasonal wetland and open water areas from six oxbow lakes in the Mississippi River alluvial flood plain were analyzed. Wetland sediments generally had higher levels of Hg than open water areas owing to a greater fraction of fine particles and higher levels of organic matter. Annual loading of Hg in open water areas was estimated at 4.3, 13.4, 19.2, 20.7, 129, and 135 ng cm(-2) yr(-1) for Beasley, Roundaway, Hampton, Washington, Wolf and Sky Lakes, respectively. Generally, the interval with the highest Hg flux was dated to the 1960s and 1970s. PMID:25847156

  17. Remineralization rates, recycling, and storage of carbon in Amazon shelf sediments

    NASA Astrophysics Data System (ADS)

    Aller, R. C.; Blair, N. E.; Xia, Q.; Rude, P. D.

    1996-04-01

    Diagenetic reactions and redox properties of Amazon shelf sediments are characterized by extensive vertical and lateral regions of Fe and Mn cycling. This is in contrast to many temperate estuarine and shelf deposits where S can dominate early diagenesis, but may be typical of wet-tropical regions draining highly weathered terrain with energetic coastlines. Although the major pathways of C org remineralization in surfical sediments apparently differ from previously studied areas, the absolute magnitude and relative importance of benthic decomposition on the Amazon shelf are comparable to many shallow water regions of equivalent depth range (10-40 m). Net ?C0 2 production over the upper ˜1-2 m of deposits is >50 mmol m -2 d -1 and has a predominantly planktonic isotopic composition (? 13C˜-21to-22%‰), indicating that marine organic matter largely drives diagenesic reactions and that >20% of average water-column primary production is metabolized on the seafloor. The ?CO 2 production rates in the upper 0-5 cm of sediment tend to increase slightly alongshelf away from the turbid river mouth, but are relatively uniform within cross-shelf transects any given season and independent of net sedimentation rate. Near uniformity in surface decomposition rates, despite substantial offshore increases in water-column productivity and net accumulation at the delta front, implies rapid cross-shelf particle exchange by estuarine circulation and tidal currents. Build-up patterns of pore-water ?CO 2 indicate in some cases that the upper ˜20 cm was deposited only a few days prior to core collection. Benthic ?C0 2 production is highest during periods of low or falling river flow, but no dramatic seasonality occurs. O 2 penetrates ˜2-4 mm into sediments and diffusive OZ uptake averages ˜13 mmol m -2 d -1 annually. Anaerobic metabolism accounts for >75% of sedimentary remineralization, but C/S burial ratios are usually >6 (average world shelf |2.8). Seasonal patterns in sedimentary Fe oxidation states indicate that sediments can be partially reoxidized to depths ˜0.6-1 m during erosion/redeposition and that subsequent Fe reduction can account for much of the anaerobic decomposition. Diffusive ?C0 2 fluxes and pore-water inventories imply substantial loss of remineralized C to authigenic sedimentary-carbonate formation or flux imbalances due to nonsteady-state ingrowth of disturbed pore-water profiles. Reoxidation of metabolites and nutrient release to the water column occur during massive physical remobilization of sediments. The total benthic N remineralization flux (recycled) is comparable to external riverine and shelf-upwelling fluxes. During stable seabed periods, however, little or no co-remineralized N (N 4+, N0 3-, NO 2- or P escapes diffusively into overlying water, indicating the potential for loss of up to ˜100% of the benthic remineralized N (by denitrification) and P (during authigenic mineral precipitation and adsorption). Overall, the shelf apparently acts as an efficient, fluidized-bed denitrification processor (˜50% recycled N) but an inefficient burial sink for riverine and upwelled N. In contrast to the atmospheric sink for N, rapidly regenerated P is eventually lost to the open ocean during sediment resuspension and desorption into the overlying water. Approximately 90% of the remineralized ?CO 2 production flux escapes the sediment and ˜10% is permanently buried as authigenic carbonate. Despite reoxidation and carbonate dissolution during reworking, net burial of C is ˜5 x 10 12 g C total per year, of which ˜25-30% is carbonate from remineralized organics (˜70% of this fraction is marine) ˜20% is residual marine C org, and the remaining (˜50% is residual terrestrial C org. "Refractory" terrestrial POC is apparently subject to repetitive co-oxidation and redox cycling, resulting in remineralization of ˜65-70% of input and leaving less than ˜30-35% of the riverine POC flux stored on the shelf.

  18. Heavy metals in surface sediments of the Jialu River, China: their relations to environmental factors.

    PubMed

    Fu, Jie; Zhao, Changpo; Luo, Yupeng; Liu, Chunsheng; Kyzas, George Z; Luo, Yin; Zhao, Dongye; An, Shuqing; Zhu, Hailiang

    2014-04-15

    This work investigated heavy metal pollution in surface sediments of the Jialu River, China. Sediment samples were collected at 19 sites along the river in connection with field surveys and the total concentrations were determined using atomic fluorescence spectrometer and inductively coupled plasma optical emission spectrometer. Sediment samples with higher metal concentrations were collected from the upper reach of the river, while sediments in the middle and lower reaches had relatively lower metal concentrations. Multivariate techniques including Pearson correlation, hierarchical cluster and principal components analysis were used to evaluate the metal sources. The ecological risk associated with the heavy metals in sediments was rated as moderate based on the assessments using methods of consensus-based Sediment Quality Guidelines, Potential Ecological Risk Index and Geo-accumulation Index. The relations between heavy metals and various environmental factors (i.e., chemical properties of sediments, water quality indices and aquatic organism indices) were also studied. Nitrate nitrogen, total nitrogen, and total polycyclic aromatic hydrocarbons concentrations in sediments showed a co-release behavior with heavy metals. Ammonia nitrogen, total nitrogen, orthophosphate, total phosphate and permanganate index in water were found to be related to metal sedimentation. Heavy metals in sediments posed a potential impact on the benthos community. PMID:24561322

  19. Analysis of sediment production from two small semiarid basins in Wyoming

    USGS Publications Warehouse

    Rankl, J.G.

    1987-01-01

    Data were collected at two small, semiarid basins in Wyoming to determine the relation between rainfall, runoff, and sediment production. The basins were Dugout Creek tributary and Saint Marys Ditch tributary. Sufficient rainfall and runoff data were collected at Dugout Creek tributary to determine the source of sediment and the dominant sediment production processes. Because runoff from only one storm occurred in Saint Marys Ditch tributary, emphasis of the study was placed on the analysis of data collected at Dugout Creek tributary. At Dugout Creek tributary, detailed measurements were made to establish the source of sediment. To determine the quantity of material removed from headcuts during the study, two headcuts were surveyed. Aerial photographs were used to define movement of all headcuts. The total quantity of sediment removed from all headcuts between September 26, 1982, and September 26, 1983, was estimated to be 1,220 tons, or 15%-25% of the estimated total sediment load passing the streamflow-gaging station. A soil plot was used to sample upland erosion. A rainfall and runoff modeling system was used to evaluate the interaction between the physical processes which control sediment production. The greatest change in computed sediment load was caused by changing the parameter values for equations used to compute the detachment of sediment particles by rainfall and overland flow resulted in very small changes in computed sediment load. The upland areas were the primary source of sediment. A relationship was developed between the peak of storm runoff and the total sediment load for that storm runoff. The sediment concentration used to compute the total sediment load for the storm runoff was determined from sediment samples collected by two automatic pumping samplers. The coefficient of variation of the relationship is 34% with a 0.99 correlation coefficient. (Author 's abstract)

  20. Effect of erosion-control structures on sediment and nutrient transport, Edgewood Creek drainage, Lake Tahoe basin, Nevada, 1981-83

    USGS Publications Warehouse

    Garcia, K.T.

    1988-01-01

    Three sites in the Edgewood Creek basin with a combined drainage area of about 1.2 sq mi were selected to assess the effect of erosion-control structures along Nevada State Highway 207, on sediment and nutrient transport. The flow at site one is thought to have been largely unaffected by urban development, and was completely unaffected by erosion control structures. The flow at site two was from a basin affected by urban development and erosion control structures. Site three was downstream from the confluence of streams measured at sites one and two. Most data on streamflow and water quality were collected between June 1981 and May 1983 to assess the hydrologic characteristics of the three sites. As a result of the erosion control structures, mean annual concentrations of total sediment were reduced from about 24,000 to about 410 mg/l at site two and from about 1,900 to about 190 ml/l at site three. Sediment loads were reduced from about 240 to about 10 tons/year at site two and from about 550 to about 110 tons/year at site three. At site one, in contrast, mean concentrations and loads remained low throughout the study period. At site two, sediment particle size changed from predominately coarse prior to construction, to predominately fine thereafter; at site three, it changed from about half coarse sediments to predominately fine. Mean concentration and loads of total iron also were significantly reduced after construction at sites two and three, whereas mean concentrations of nitrogen and phosphorus species did not change appreciably. (Author 's abstract)

  1. 75 FR 63805 - Annual Wholesale Trade Survey

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-18

    ...will collect data on annual sales, e-commerce sales, purchases, total operating...will collect data covering sales, e-commerce sales, year-end inventories held...collect data covering annual sales, e-commerce sales, year-end inventories...

  2. 35th Annual Official Education Construction Report

    ERIC Educational Resources Information Center

    Agron, Joe

    2009-01-01

    Spending on construction by the nation's education institutions increased in 2008, reversing four years of declines in total annual expenditures, according to "American School & University"'s 35th annual Official Education Construction Report. One of the reasons for the increase in spending was the fact that the majority of the construction…

  3. CALCULATING SEDIMENT COMPACTION FOR RADIOCARBON DATING OF INTERTIDAL SEDIMENTS

    Microsoft Academic Search

    M I Bird; L K Fifield; S Chua; B Goh

    2004-01-01

    This study estimates the maximum and minimum degrees of autocompaction for radiocarbon-dated Holocene mangrove sediments in Singapore, in order to correct apparent sediment accretion rates for the effects of sediment compres- sion due to autocompaction. Relationships developed for a suite of modern (surface) sediment samples between bulk density, particle-size distribution, and organic matter content were used to estimate the initial

  4. A new sampler design for measuring sedimentation in streams

    USGS Publications Warehouse

    Hedrick, Lara B.; Welsh, S.A.; Hedrick, J.D.

    2005-01-01

    Sedimentation alters aquatic habitats and negatively affects fish and invertebrate communities but is difficult to quantify. To monitor bed load sedimentation, we designed a sampler with a 10.16-cm polyvinyl chloride coupling and removable sediment trap. We conducted a trial study of our samplers in riffle and pool habitats upstream and downstream of highway construction on a first-order Appalachian stream. Sediment samples were collected over three 6-week intervals, dried, and separated into five size-classes by means of nested sieves (U.S. standard sieve numbers 4, 8, 14, and 20). Downstream sediment accumulated in size-classes 1 and 2, and the total amount accumulated was significantly greater during all three sampling periods. Size-classes 3 and 4 had significantly greater amounts of sediment for the first two sampling periods at the downstream site. Differences between upstream and downstream sites narrowed during the 5-month sampling period. This probably reflects changes in site conditions, including the addition of more effective sediment control measures after the first 6-week period of the study. The sediment sampler design allowed for long-term placement of traps without continual disturbance of the streambed and was successful at providing repeat measures of sediment at paired sites. ?? Copyright by the American Fisheries Society 2005.

  5. Seismic interpretation of pelagic sedimentation regimes in the 18-53 Ma eastern equatorial Pacific: Basin-scale sedimentation and infilling of abyssal valleys

    NASA Astrophysics Data System (ADS)

    Tominaga, Masako; Lyle, Mitchell; Mitchell, Neil C.

    2011-03-01

    Understanding how pelagic sediment has been eroded, transported, and deposited is critical to evaluating pelagic sediment records for paleoceanography. We use digital seismic reflection data from an Integrated Ocean Drilling Program site survey (AMAT03) to investigate pelagic sedimentation across the eastern-central equatorial Pacific, which represents the first comprehensive record published covering the 18-53 Ma eastern equatorial Pacific. Our goals are to quantify (1) basin-hill-scale primary deposition regimes and (2) the extent to which seafloor topography has been subdued by abyssal valley-filling sediments. The eastern Pacific seafloor consists of a series of abyssal hills and basins, with minor late stage faulting in the basement. Ocean crust rarely outcrops at the seafloor away from the rise crest; both hills and basins are sediment covered. The carbonate compensation depth is identified at 4440 m by the appearance of acoustically transparent clay intervals in the seismic data. Overall, we recognized three different sedimentation regimes: depositional (high sedimentation rate), transitional, and minimal sedimentation (low sedimentation rate) regimes. In all areas, the sedimented seafloor mimics the underlying basement topography, although the degree to which topography becomes subdued varies. Depositional regimes result in symmetric sedimentation within basins and subdued topography, whereas minimal sedimentation regimes have more asymmetric distribution of sediments within topographic lows and higher seafloor relief. Regardless of sedimentation regime, enhanced sediment deposition occurs within basins. However, we observe that basin infill is rarely more than twice as thick as sediment cover over abyssal hills. If this variation is due to sediment focusing, the focusing factor in the basins, as measured by 230Th, is no more than a factor of ˜1.3 of the total vertical particulate rain.

  6. Coal industry annual 1997

    SciTech Connect

    NONE

    1998-12-01

    Coal Industry Annual 1997 provides comprehensive information about US coal production, number of mines, prices, productivity, employment, productive capacity, and recoverable reserves. US Coal production for 1997 and previous years is based on the annual survey EIA-7A, Coal Production Report. This report presents data on coal consumption, coal distribution, coal stocks, coal prices, and coal quality for Congress, Federal and State agencies, the coal industry, and the general public. Appendix A contains a compilation of coal statistics for the major coal-producing States. This report includes a national total coal consumption for nonutility power producers that are not in the manufacturing, agriculture, mining, construction, or commercial sectors. 14 figs., 145 tabs.

  7. Factors influencing polycyclic aromatic hydrocarbon distributions in South Carolina estuarine sediments

    Microsoft Academic Search

    John R. Kucklick; Scott K. Sivertsen; Marion Sanders; Geoffrey I. Scott

    1997-01-01

    Surface (2 cm) sediment was collected from three South Carolina estuaries, Winyah Bay, Charleston Harbor and the North Edisto River estuary for a total of 64 samples. The sediment samples were analyzed for 24 individual polycyclic aromatic hydrocarbons (PAHs; two to six rings) by gas chromatography with ion trap mass spectrometric detection. Concentrations of total PAHs were extremely variable, ranging

  8. 25 CFR 39.710 - How does a school calculate annual bus transportation miles for day students?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...annual bus transportation miles for day students? 39.710 Section 39.710 Indians...THE INDIAN SCHOOL EQUALIZATION PROGRAM Student Transportation Calculating Transportation...annual bus transportation miles for day students? To calculate the total annual...

  9. 25 CFR 39.710 - How does a school calculate annual bus transportation miles for day students?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...annual bus transportation miles for day students? 39.710 Section 39.710 Indians...THE INDIAN SCHOOL EQUALIZATION PROGRAM Student Transportation Calculating Transportation...annual bus transportation miles for day students? To calculate the total annual...

  10. 25 CFR 39.710 - How does a school calculate annual bus transportation miles for day students?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...annual bus transportation miles for day students? 39.710 Section 39.710 Indians...THE INDIAN SCHOOL EQUALIZATION PROGRAM Student Transportation Calculating Transportation...annual bus transportation miles for day students? To calculate the total annual...

  11. 25 CFR 39.710 - How does a school calculate annual bus transportation miles for day students?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...annual bus transportation miles for day students? 39.710 Section 39.710 Indians...THE INDIAN SCHOOL EQUALIZATION PROGRAM Student Transportation Calculating Transportation...annual bus transportation miles for day students? To calculate the total annual...

  12. 25 CFR 39.710 - How does a school calculate annual bus transportation miles for day students?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...annual bus transportation miles for day students? 39.710 Section 39.710 Indians...THE INDIAN SCHOOL EQUALIZATION PROGRAM Student Transportation Calculating Transportation...annual bus transportation miles for day students? To calculate the total annual...

  13. Diffusive transport of organic colloids from sediment beds

    SciTech Connect

    Valsaraj, K.T.; Verma, S.; Sojitra, I.; Reible, D.D.; Thibodeaux, L.J. [Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Chemical Engineering

    1996-08-01

    Organic colloids resulting from sediment diagenesis in porewaters are transported across the sediment-water interface via Brownian diffusion. The sediment selected for this study was from the University Lake, Baton Rouge, La. The effects of electrolytes on the sediment-to-water flux of colloids varied depending on the type and concentration of the electrolyte. An ionic strength of 0.5 M reduced the flux of colloids; the effect being greater for KCl than for NaCl at the same ionic strength. The effects of different electrolytes (viz., NaCl, KCl, and CaCl{sub 2}) on the porewater colloid concentrations were studied in batch experiments. Below the ionic strength of 0.5 M, the electrolytes were effective in increasing the binding of the colloids to sediment surfaces, and hence decreased their pore-water concentrations. Above the ionic strength of 0.5 M, the amount of colloids released to the porewater was greatest in the presence of CaCl{sub 2}. The diffusive flux of colloids from sediment to water was modeled using an effective diffusivity as the single adjustable parameter. The effective diffusivity (D{sub eff}) was obtained using two complementary techniques. The first method utilized the sediment-to-water flux of colloids, which was fit to a model to extract D{sub eff}. For the second method, postmortem cores of the sediment were obtained after 82 d, the porewater colloids were extracted and analyzed. The porewater colloid profile as a function of sediment depth was used to obtain D{sub eff}. The effects of sediment diagenesis on the porewater colloids and the sediment total organic carbon (TOC) in a natural environment are illustrated using data from New Bedford Harbor (NBH), Mass. For this specific case only 0.43% of the organic matter delivered to the sediment was found to reappear in the water column as dissolved species.

  14. MAINTAINING ACCESS TO AMERICA'S INTERMODAL PORTS\\/TECHNOLOGIES FOR DECONTAMINATION OF DREDGED SEDIMENT: NEW YORK\\/NEW JERSEY HARBOR

    Microsoft Academic Search

    Eric A. Stern; Keith W. Jones; Kerwin Donato; John D. Pauling; J. G. SONTAG; N. L. CLESCERI; M. C. MENSINGER; C. L. WILDE

    1998-01-01

    One of the greatest drivers for maintaining access to America's Intermodal ports and related infrastructure redevelopment efforts over the next several years will be the control and treatment of contaminated sediments dredged from the nation's waterways. More than 306 million cubic meters (m³) (400 million cubic yards [cy]) of sediments are dredged annually from US waterways, and each year close

  15. The effects of disequilibria in the uranium and thorium decay chains on burial dose rates in fluvial sediments

    Microsoft Academic Search

    Jon M. Olley; Andrew Murray; Richard G. Roberts

    1996-01-01

    Buried sediments receive about 53% of their annual dose of ionising radiation from radionuclides in the uranium and thorium decay chains. In luminescence dating of sediment samples, it is usually assumed that the dose rate does not change over the period of burial, implying that the uranium and thorium decay series are in secular equilibrium. For the 232Th decay chain

  16. Effects of urban best management practices on streamflow and phosphorus and suspended-sediment transport on Englesby Brook in Burlington, Vermont, 2000-2010

    USGS Publications Warehouse

    Medalie, Laura

    2012-01-01

    An assessment of the effectiveness of several urban best management practice structures, including a wet extended detention facility and a shallow marsh wetland (together the "wet extended detention ponds"), was made using data collected from 2000 through 2010 at Englesby Brook in Burlington, Vermont. The purpose of the best management practices was to reduce high streamflows and phosphorus and suspended-sediment loads and concentrations and to increase low streamflows. Englesby Brook was monitored for streamflow, phosphorus, and suspended-sediment concentrations at a streamgage downstream of the best management practice structures for 5 years before the wet extended detention ponds were constructed in 2005 and for 4 years (phosphorus and suspended-sediment concentrations) or 5 years (streamflow) after they were constructed. The period after construction of the best management practice structures was wetter and had higher discharges than the period before construction. Despite the wetter conditions, streamflow duration curves provided evidence that the streamflow regime appeared to have shifted so that the percentages of low streamflows have increased and those of high streamflows may have slightly decreased. Two other hydrologic measures showed improvements in the years following construction of the best management practices: the percentage of annual discharge transported during the 3 days with highest discharges and the number of days with zero streamflow have both decreased. Evidence was mixed for the effectiveness of the best management practices in reducing phosphorus and suspended-sediment concentrations and loads. Annual phosphorus and suspended-sediment loads, monthly loads, low-streamflow concentrations, storm-averaged streamflow-adjusted concentrations, and total storm loads either did not change significantly or increased in the period after construction. These results likely were because of the wetter conditions in the period after construction. For example, monthly loads assessed using analysis of covariance, which compensated for the effects of streamflow on loads, suggested no difference in phosphorus or suspended-sediment loads between the two periods, whereas the comparison of monthly loads without factoring in streamflow showed an increase. This result could be viewed as evidence that the ponds may have mitigated the effect of greater discharges in the period after construction by preventing a corresponding increase in loads. In another analysis used to adjust for the difference in discharge between the two comparison periods, annual and monthly load results were grouped into dry and wet years. Large (50 percent) reductions in annual loads were observed when data from dry (or wet) years before construction were compared with data from dry (or wet) years after construction. When paired monthly loads of each constituent were grouped into dry and wet years, approximately the same number of months had increases as did decreases with the magnitudes of the decreases generally larger than the magnitudes of the increases. These differences in magnitude explain the decrease in annual loads for dry and wet years. The close association of phosphorus with suspended-sediment data suggested that most of the phosphorus was in the particulate form and was controlled by suspended-sediment dynamics.

  17. 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...

  18. Microcystin concentrations in the Nile River sediments and removal of microcystin-LR by sediments during batch experiments.

    PubMed

    Mohamed, Zakaria A; El-Sharouny, Hassan M; Ali, Wafaa S

    2007-05-01

    During the present study, microcystin (MCYST) concentrations in the Nile River and irrigation canal sediments, Egypt, were investigated during the period January-December 2001. Batch experiments were also conducted to confirm the adsorption of MCYSTs on these sediments. The results of field study showed that MCYST concentrations in the sediments were correlated with total count of cyanobacteria, particularly Microcystis aeruginosa, and MCYST within phytoplankton cells in most sites. No detectable levels of MCYSTs were found in the cell-free water of all studied sites in the Nile River and irrigation canals during the entire study period. The data obtained from batch adsorption experiments confirmed the capability of the Nile River and irrigation canal sediments for MCYST adsorption; and that adsorption was sediment weight-dependent and thus fitted the Freundlich adsorption isotherm. The results also revealed that both adsorption capacity (K(f)) and intensity (1/n) varied significantly with clay and organic matter contents of these sediments. The results of present study have two implications. First, the presence of cyanobacterial toxins in freshwater sediments can affect benthic organisms inhabiting these sediments, and thus it should be considered during biological monitoring of rivers and streams. Second, the ability of freshwater sediments to adsorb cyanobacterial toxins suggests that bank filtration could be used in developing countries (e.g., Egypt), which require an inexpensive and low-maintenance method for removing these toxins from drinking water. PMID:17380237

  19. Temperature-controlled organic carbon mineralization in lake sediments.

    PubMed

    Gudasz, Cristian; Bastviken, David; Steger, Kristin; Premke, Katrin; Sobek, Sebastian; Tranvik, Lars J

    2010-07-22

    Peatlands, soils and the ocean floor are well-recognized as sites of organic carbon accumulation and represent important global carbon sinks. Although the annual burial of organic carbon in lakes and reservoirs exceeds that of ocean sediments, these inland waters are components of the global carbon cycle that receive only limited attention. Of the organic carbon that is being deposited onto the sediments, a certain proportion will be mineralized and the remainder will be buried over geological timescales. Here we assess the relationship between sediment organic carbon mineralization and temperature in a cross-system survey of boreal lakes in Sweden, and with input from a compilation of published data from a wide range of lakes that differ with respect to climate, productivity and organic carbon source. We find that the mineralization of organic carbon in lake sediments exhibits a strongly positive relationship with temperature, which suggests that warmer water temperatures lead to more mineralization and less organic carbon burial. Assuming that future organic carbon delivery to the lake sediments will be similar to that under present-day conditions, we estimate that temperature increases following the latest scenarios presented by the Intergovernmental Panel on Climate Change could result in a 4-27 per cent (0.9-6.4 Tg C yr(-1)) decrease in annual organic carbon burial in boreal lakes. PMID:20651689

  20. Monitoring sediment transfer processes on the desert margin

    NASA Technical Reports Server (NTRS)

    Millington, Andrew C.; Arwyn, R. Jones; Quarmby, Neil; Townshend, John R. G.

    1987-01-01

    LANDSAT Thematic Mapper and Multispectral Scanner data have been used to construct change detection images for three playas in south-central Tunisia. Change detection images have been used to analyze changes in surface reflectance and absorption between wet and dry season (intra-annual change) and between different years (inter-annual change). Change detection imagery has been used to examine geomorphological changes on the playas. Changes in geomorphological phenomena are interpreted from changes in soil and foliar moisture levels, differences in reflectances between different salt and sediments and the spatial expression of geomorphological features. Intra-annual change phenomena that can be detected from multidate imagery are changes in surface moisture, texture and chemical composition, vegetation cover and the extent of aeolian activity. Inter-annual change phenomena are divisible into those restricted to marginal playa facies (sedimentation from sheetwash and alluvial fans, erosion from surface runoff and cliff retreat) and these are found in central playa facies which are related to the internal redistribution of water, salt and sediment.

  1. Nucleic acid concentrations (DNA, RNA) in the continental and deep-sea sediments of the eastern Mediterranean: relationships with seasonally varying organic inputs and bacterial dynamics

    NASA Astrophysics Data System (ADS)

    Danovaro, R.; Dell'anno, A.; Pusceddu, A.; Fabiano, M.

    1999-06-01

    In order to study temporal variations of the genetic material in the continental shelf and deep-sea sediments of the extremely oligotrophic Cretan Sea, samples were collected on seasonal basis from August 1994 to September 1995, with a multiple corer, at seven stations (from 40 to 1540 m depth). Surface sediments (0-1 cm) were sub-sampled and analyzed for nucleic acid content (DNA, RNA) and bacterial density. DNA concentrations in the sediments were high (on annual average, 25.0 ?g g -1) and declined with increasing water depth, ranging from 3.5 to 55.2 ?g g -1. DNA concentrations displayed wide temporal changes also at bathyal depths confirming the recent view of the large variability of the deep-sea environments. Also RNA concentrations decreased with increasing water depth (range: 0.4-29.9 ?g g -1). The ratio of RNA to DNA did not show a clear spatial pattern but was characterized by significant changes between sampling periods. DNA concentrations were significantly correlated with protein and phytopigment concentrations in the sediment, indicating a possible relationship with the inputs of primary organic matter from the photic layer. Bacterial densities were generally high (range: 0.9-4.6×10 8 cells g -1) compared to other deep-sea environments and decreased with increasing water depth. Estimates of the bacterial contribution to the sedimentary genetic material indicated that bacterial-DNA accounted, on annual average, for a small fraction of the total DNA pool (4.3%) but that bacterial-RNA represented a significant fraction of the total sedimentary RNA (26%). Bacterial contribution to nucleic acids increased, even though irregularly, with increasing depth. In deep-sea sediments, changes in RNA concentrations appear to be largely dependent upon bacterial dynamics. Estimates of the overall living contribution to the DNA pools (i.e. microbial plus meiofaunal DNA) indicated that the large majority (about 90%) of the DNA in continental and deep-sea sediments of the eastern Mediterranean was detrital. The non-living DNA pools reach extremely high concentrations up to 0.41 g DNA m -2 cm -1. Thus, especially in deep benthic habitats, characterized by low inputs of labile organic compounds, detrital DNA could represent a suitable and high quality food source or a significant reservoir of nucleic acid precursors for benthic metabolism.

  2. Wayne Interim Storage Site. Annual site environmental report, calendar year 1985. Formerly Utilized Sites Remedial Action Program (FUSRAP). [FUSRAP

    SciTech Connect

    Not Available

    1986-08-01

    The monitoring program at the Wayne Interim Storage Site (WISS) measures uranium, radium, and thorium concentrations in surface water, groundwater, and sediment; radon and thoron gas concentrations in air; and external gamma radiation dose rates. Potential radiation doses to the public are also calculated. During 1985, annual average thoron concentrations at the WISS ranged from 1 to 11% of the DOE guide. Annual average radon concentrations ranged from 13 to 39% of the DOE guide. The highest measured external dose rate at the WISS was 606 mrem/y, which is about six times the natural background rate and is in an area of known contamination. The highest average annual concentration of uranium in surface water monitored in the vicinity of the WISS was 3.2% of the Derived Concentration Guide; for /sup 232/Th it was 2.2%; for /sup 226/Ra it was 0.3%; and for radium-228 it was 3.0%. In groundwater, the highest annual average concentration of uranium was 2.4% of the Derived Concentration Guide; for /sup 232/Th it was 1.4%; for /sup 226/Ra it was 0.9%; and for /sup 228/Ra it was 2.7%. While there are no concentration guides for stream sediments, the highest annual average concentration of total uranium was 2.70 pCi/g, for /sup 232/Th it was 3.78 pCi/g, for /sup 226/Ra it was 5.10 pCi/g, and for /sup 228/Ra it was 6.90 pCi/g. These concentrations are below or approximately equal to the decontamination criteria. Radon concentrations and external gamma dose rates at the site were lower than those measured in 1984. Radionuclide concentrations in surface water were equal to background levels, and groundwater concentrations were similar to 1984 levels. For sediments, insufficient data are available to permit the establishment of trends. The calculated total radiation dose to the maximally exposed individual at the WISS, considering several exposure pathways, was 7 mrem, or 7% of the DOE radiation protection standard.

  3. Re-suspension of bed sediment in a small stream - results from two flushing experiments

    NASA Astrophysics Data System (ADS)

    Eder, A.; Exner-Kittridge, M.; Strauss, P.; Blöschl, G.

    2014-03-01

    Streams draining small watersheds often exhibit multiple peaking sedigraphs associated with single peaking hydrographs. The process reasons of the multiple sediment peaks are not fully understood but they may be related to the activation of different sediment sources such as the stream bed itself, where deposited sediments from previous events may be available for resuspension. To understand resuspension of stream bed sediments at the reach scale we artificially flooded the small stream of the HOAL Petzenkirchen catchment in Austria by pumping sediment-free water into the stream. Two short floods were produced and flow, sediment and bromide concentrations were measured at three sites with high temporal resolution. Hydrologically, the two flood events were almost identical. The peak flows decreased from 57 to 7.9 L s-1 and the flow volumes decreased from 17 to 11.3 m2 along the 590 m reach of the stream. However, a considerably smaller sediment load was resuspended and transported during the second flood due to depletion of stream bed sediments. The exception was the middle section of the stream, where more sediment was transported during the second flood event which can be explained by differences between flow velocity and wave celerity and the resulting displacement of sediments within the stream. The results indicate that the first peak of the sedigraphs of natural events in this stream is indeed caused by the resuspension of stream bed sediments, accounting for up to six percent of the total sediment load depending on total flow volume.

  4. Tribal Training -- Sediment Devices

    USGS Multimedia Gallery

    USGS Research Hydrologist Art Horowitz and USGS Oklahoma Water Science Center Hydrologic Technician Ernie Smith describe streambed sediment collection devices for a Tribal training class at the Canadian River, Norman, Oklahoma....

  5. Annual Report FY2012 University of Rhode Island

    E-print Network

    Rhode Island, University of

    Annual Report FY2012 University of Rhode Island Division of Research and Economic Development 6 Development FY1991 - FY2012 #12;Annual Report FY2012 University of Rhode Island Division of Research FY1991 - FY2012 Totals in $Millions #12;Annual Report FY2012 University of Rhode Island Division

  6. Deposition of selenium and other constituents in reservoir bottom sediment of the Solomon River Basin, north-central Kansas

    USGS Publications Warehouse

    Christensen, Victoria G.

    1999-01-01

    The Solomon River drains approximately 6,840 square miles of mainly agricultural land in north-central Kansas. The Bureau of Reclamation, U.S. Department of the Interior, has begun a Resource Management Assessment (RMA) of the Solomon River Basin to provide the necessary data for National Environmental Policy Act (NEPA) compliance before renewal of long-term water-service contracts with irrigation districts in the basin. In May 1998, the U.S. Geological Survey (USGS) collected bottom-sediment cores from Kirwin and Webster Reservoirs, which are not affected by Bureau irrigation, and Waconda Lake, which receives water from both Bureau and non-Bureau irrigated lands. The cores were analyzed for selected physical properties, total recoverable metals, nutrients, cesium-137, and total organic carbon. Spearman's rho correlations and Kendall's tau trend tests were done for sediment concentrations in cores from each reservoir. Selenium, arsenic, and strontium were the only constituents that showed an increasing trend in concentrations for core samples from more than one reservoir. Concentrations and trends for these three constituents were compared to information on historical irrigation to determine any causal effect. Increases in selenium, arsenic, and strontium concentrations can not be completely explained by Bureau irrigation. However, mean selenium, arsenic, and strontium concentrations in sediment from all three reservoirs may be related to total irrigated acres (Bureau and non-Bureau irrigation) in the basin. Selenium, arsenic, and strontium loads were calculated for Webster Reservoir to determine if annual loads deposited in the reservoir were increasing along with constituent concentrations. Background selenium, arsenic, and strontium loads in Webster Reservoir are significantly larger than post-background loads.

  7. Ultrahigh resolution total organic carbon analysis using Fourier Transform Near Infrarred Reflectance Spectroscopy (FT-NIRS)

    NASA Astrophysics Data System (ADS)

    Pearson, Emma J.; Juggins, Steve; Tyler, Jonathan

    2014-01-01

    Fourier transform near infrared reflectance spectroscopy (FT-NIRS) is a cheap, rapid, and nondestructive method for analyzing organic sediment components. Here, we examine the robustness of a within lake FT-NIRS calibration using a data set of almost 400 core samples from Lake Suigetsu, Japan, as a means to rapidly reconstruct % total organic carbon (TOC). We evaluate the best spectra pretreatment, examine different statistical approaches, and provide recommendations for the optimum number of calibration samples required for accurate predictions. Results show that the most robust method is based on first-order derivatives of all spectra modeled with partial least squares regression. We construct a TOC model training set using 247 samples and a validation test set using 135 samples (for test set R2 = 0.951, RMSE = 0.280) to determine TOC and illustrate the use of the model in an ultrahigh resolution (e.g., 1 mm/annual) study of a long sediment core from a climatically sensitive archive.

  8. Paying your annual allowance charge from your pension savings You will be liable to the annual allowance charge if your pension savings are more

    E-print Network

    Painter, Kevin

    Paying your annual allowance charge from your pension savings You will be liable to the annual allowance charge if your pension savings are more than the total of the annual allowance for the year plus to report any excess pension savings over the annual allowance (after utilising any unused allowance you

  9. Anthropogenic sources of arsenic and copper to sediments in a Suburban Lake, Northern Virginia

    USGS Publications Warehouse

    Rice, K.C.; Conko, K.M.; Hornberger, G.M.

    2002-01-01

    Mass balances of total arsenic and copper for a suburban lake in densely populated northern Virginia were calculated using data collected during 1998. Mass-balance terms were precipitation; stream inflow, including road runoff; stream outflow; and contributions from leaching of pressure-treated lumber. More mass of arsenic and copper was input to the lake than was output; the 1998 lake-retention rates were 70% for arsenic and 20% for copper. The arsenic mass balance compared well with a calculated annual mass accumulation in the top 1 cm of the lake sediments; however, the calculated contribution of copper to the lake was insufficient to account for the amount of copper in this zone. Leaching experiments were conducted on lumber treated with chromated copper arsenate (CCA) to quantify approximate amounts of arsenic and copper contributed by this source. Sources to lake sediments included leaching of CCA-treated lumber (arsenic, 50%; copper, 4%), streamwater (arsenic, 50%; copper, 90%), and atmospheric deposition (arsenic, 1%; copper, 3%). Results of this study suggest that CCA-treated lumber and road runoff could be significant nonpoint sources of arsenic and copper, respectively, in suburban catchments.

  10. Estimation of erosion and sediment export from an agricultural catchment (1960 - 2000) confronting the outputs of an expert-based model and Cs-137 inventories

    NASA Astrophysics Data System (ADS)

    Evrard, Olivier; Nord, Guillaume; Cerdan, Olivier; Souchère, Véronique; Le Bissonnais, Yves; Bonté, Philippe

    2010-05-01

    Soil erosion leads to important environmental problems (e.g. muddy floods, reservoir sedimentation) in cultivated areas of the European loess belt. This study aimed to quantify erosion and to determine the impact of rainfall seasonality and land use change on soil erosion over the last 40 years in a 94-ha cultivated catchment of Normandy (France). To this end, scenarios representative of the different land use conditions were simulated using the STREAM expert-based erosion model. A 13-yrs long sequence of rainfall events was run with this model. Results showed that erosion increased dramatically after land consolidation (+168% on average). Interannual variability of erosion is important. After land consolidation, 79% of erosion was observed in summer and autumn, even though these seasons only accounted for 58% of annual rainfall kinetic energy. The bulk of erosion was hence produced by a few intense thunderstorms during this period. Thunderstorms correspond to 5% of rainfall events, but they generate 51% of total annual erosion after land consolidation (and up to 57% of erosion before land consolidation). Confrontation of the model outputs with the erosion rates derived from Cs-137 measurements suggested that soil redistribution within the catchment was very high but that sediment exports from the catchment remained limited (sediment delivery ratio between 1 - 10%). Erosion rates derived from Cs-137 measurements showed an important and organised spatial variability, but erosion rates integrated over larger areas remained in the same order of magnitude than those simulated by the model or were slightly higher. Water erosion would hence not be the only process generating erosion within this catchment. In this context, tillage erosion cannot be neglected to calculate the sediment budget over several decades. These findings show the necessity to simulate sequences of rainfall events to obtain reliable erosion predictions. They also demonstrate the interest of developping expert-based models simulating both water and tillage erosion at the catchment scale to conduct erosion studies over several decades.

  11. Potential effects of runoff, fluvial sediment, and nutrient discharges on the coral reefs of Puerto Rico

    USGS Publications Warehouse

    Larsen, M.C.; Webb, R.M.T.

    2009-01-01

    Coral reefs, the foundation and primary structure of many highly productive and diverse tropical marine ecosystems, have been degraded by human activity in much of the earth's tropical oceans. To contribute to improved understanding of this problem, the potential relation between river sediment and nutrient discharges and degradation of coral reefs surrounding Puerto Rico was studied using streamflow, suspended-sediment, and water-quality data. Mean annual runoff for the 8711 km2 island is 911 mm, about 57% of mean annual precipitation (1600 mm). Mean annual suspended-sediment discharge from Puerto Rico to coastal waters is estimated at 2.7-9.0 million metric tonnes. Storm runoff transports a substantial part of sediment: the highest recorded daily sediment discharge is 1-3.6 times the mean annual sediment discharge. Hurricane Georges (1998) distributed an average of 300 mm of rain across the island, equivalent to a volume of about 2.6 billion m3. Runoff of more than 1.0 billion m3 of water and as much as 5 to 10 million metric tonnes of sediment were discharged to the coast and shelf. Nitrogen and phosphorous concentrations in river waters are as much as 10 times the estimated presettlement levels. Fecal coliform and fecal streptococcus concentrations in many Puerto Rico rivers are near or above regulatory limits. Unlike sediment discharges, which are predominantly episodic and intense, river-borne nutrient and fecal discharge is a less-intense but chronic stressor to coral reefs found near the mouths of rivers. Negative effects of riverderived sediment and nutrient discharge on coral reefs are especially pronounced on the north, southwest, and west coasts.

  12. Impact of Natural (Storm) and Anthropogenic (Trawl) Resuspension the Sediment Transport on the Gulf of Lion's Shelf (NW Mediterranean)

    NASA Astrophysics Data System (ADS)

    Ferre, B.; Durrieu de Madron, X.; Estournel, C.; Ulses, C.; Le Corre, G.

    2006-12-01

    Modern sediment deposits on continental margins form a vast reservoir of particulate matter that is regularly affected by resuspension processes. On shelves with strong fishing activity, resuspension by bottom trawling processes can modify the scale of natural disturbance by waves and currents. Recent field data shows that the impact of bottom trawls on the resuspension of the fine sediments per unit surface is comparable with that of the largest storms. We assessed the impact of both natural and anthropogenic processes on the dispersal of river-borne particles and shelf sediments on the Gulf of Lion's Shelf. Realistic numerical simulations of resuspension and transport forced by currents and waves or by a fleet of bottom trawlers were developed. Simulations were conducted for a 16-month period to characterize the seasonal variability. The sediment dynamics takes into account bed armoring, ripple geometry and the cohesive and non-cohesive characteristics of the sediment. Essential but uncertain parameters (clay content, erosion fluxes and critical shear stress for cohesive sediment) were set with existing data. Resuspension by waves and currents is controlled by the shear stress, whereas resuspension by the bottom trawler fleet is controlled by its density and distribution. Natural resuspension by waves and currents mostly occurs during short winter episodes, and is concentrated on the inner-shelf. Trawling-induced resuspension, in contrast, occurs regularly throughout the year and is concentrated on the outer shelf. The total annual net resuspension by trawls (8×106 T y-1 is four orders of magnitude lower than the resuspension induced by waves and currents (4×1010 T y-1. However, because trawled regions are located on the outer shelf, closer to the continental slope, export of fine sediment resuspended by trawls (0.6×106 T y-1 is only one order of magnitude lower than export associated with natural resuspension (8×106 T y-1. A simulation combining both resuspension processes reveals a decrease of about 10% in resuspension and export rates, compared with the sum of each individual process.

  13. Empirical and conceptual modelling of the suspended sediment dynamics in a large tropical African river: the Upper Niger river basin

    NASA Astrophysics Data System (ADS)

    Picouet, C.; Hingray, B.; Olivry, J. C.

    2001-09-01

    A 7-year sediment transport monitoring on the Upper Niger rivers was used to study the relationship between suspended sediment concentration and river discharge. During annual floods, these relationships show positive hysteresis. This paper presents the results of two models that estimate the time evolution of suspended sediment concentration using water discharge data only. The first model is based on a statistical approach using two relationships, one for the rising stage period of the flood and one for the recession period of the annual flood; the second model is a lumped conceptual one; it supposes that the sediment flux observed in the river comes from two different sources of sediment and that these two sources may be regarded as two different reservoirs. The erosion of the first reservoir represents hillslope erosion observed during the runoff season. Sediment supply from this 'reservoir' is limited in time because depletion occurs during the runoff season. The second reservoir is unlimited in time and quantity and its erosion represents contributions coming from bank erosion and mobilisation of deposits in the channel network. Both of the models are compared with a simple rating curve based model. The model results show that the conceptual model has the highest efficiency to reproduce from weekly discharge only the time evolution of weekly suspended sediment concentrations, the time evolution of weekly sediment fluxes, and the global annual sediment yields.

  14. Amino acid diagenesis, organic carbon and nitrogen mineralization in surface sediments from the inner Oslofjord, Norway

    SciTech Connect

    Haugen, J.E. (National Inst. of Public Health, Oslo (Norway)); Lichtentaler, R. (Norwegian Inst. for Water Research, Oslo (Norway))

    1991-06-01

    Total hydrolyzed amino acids (THAA), total organic carbon (TOC), and total nitrogen (TN) have been measured in an oxic and anoxic surface sediment from the inner Oslofjord. Downcore variations of these parameters are ascribed to both diagenesis and changes in organic matter supply, the latter being most important. These changes are most prominent in the anoxic sediment, which reflects the eutrophication history of the innermost part of the fjord. Downcore, THAA content decreased from 3.8 to 2.0 mg/g (salt-free dry weight) in the oxic sediment and from 22.3 to 3.8 mg/g in the anoxic sediment. Total amino acid nitrogen varied between 17 and 34% of total nitrogen in the oxic, and 25 and 54% in the anoxic, sediment. Organic carbon and organic nitrogen accumulation rates and depth integrated mineralization rates are about three times higher in the anoxic sediment than in the oxic sediment. Recycling of amino acids accounted for 4 to 12% of the total organic carbon and 13 to 40% of the total organic nitrogen regenerated in these sediments.

  15. Copper Sediment Toxicity and Partitioning during Oxidation in a Flow-Through Flume.

    PubMed

    Costello, David M; Hammerschmidt, Chad R; Burton, G Allen

    2015-06-01

    The bioavailability of transition metals in sediments often depends on redox conditions in the sediment. We explored how the physicochemistry and toxicity of anoxic Cu-amended sediments changed as they aged (i.e., naturally oxidized) in a flow-through flume. We amended two sediments (Dow and Ocoee) with Cu, incubated the sediments in a flow-through flume, and measured sediment physicochemistry and toxicity over 213 days. As sediments aged, oxygen penetrated sediment to a greater depth, the relative abundance of Fe oxides increased in surface and deep sediments, and the concentration of acid volatile sulfide declined in Ocoee surface sediments. The total pool of Cu in sediments did not change during aging, but porewater Cu, and Cu bound to amorphous Fe oxides decreased while Cu associated with crystalline Fe oxides increased. The dose-response of the epibenthic amphipod Hyalella azteca to sediment total Cu changed over time, with older sediments being less toxic than freshly spiked sediments. We observed a strong dose-response relationship between porewater Cu and H. azteca growth across all sampling periods, and measurable declines in relative growth rates were observed at concentrations below interstitial water criteria established by the U.S. EPA. Further, solid-phase bioavailability models based on AVS and organic carbon were overprotective and poorly predicted toxicity in aged sediments. We suggest that sediment quality criteria for Cu is best established from measurement of Cu in pore water rather than estimating bioavailable Cu from the various solid-phase ligands, which vary temporally and spatially. PMID:25966043

  16. Hydrographic and sedimentation survey of Kajakai Reservoir, Afghanistan

    USGS Publications Warehouse

    Perkins, Don C.; Culbertson, James K.

    1970-01-01

    A hydrographic and sedimentation survey of Band-e Kajakai (Kajakai Reservoir) on the Darya-ye Hirmand (Helmand River) was carried out during the period September through December 1968. Underwater mapping techniques were used to determine the reservoir capacity as of 1968. Sediment range lines were established and monumented to facilitate future sedimentation surveys. Afghanistan engineers and technicians were trained to carry out future reservoir surveys. Samples were obtained of the reservoir bed and in the river upstream from the reservoir. Virtually no sediments coarser than about 0.063 millimeter were found on the reservoir bed surface. The median diameter of sands being transported into the reservoir ranged from 0.040 to 0.110 millimeter. The average annual rate of sedimentation was 7,800 acre-feet. Assuming an average density of 50 pounds per cubic foot (800 kilograms per cubic meter), the estimated average sediment inflow to the reservoir was about 8,500,000 tons (7,700,000 metric tons) per year. The decrease in capacity at spillway elevation for the period 1953 to 1968 due to sediment deposition was 7.8 percent, or 117,700 acre-feet. Redefinition of several contours above the fill area resulted in an increase in capacity at spillway elevation of 13,600 acre-feet; thus, the net change in capacity was 7.0 percent, or 104,800 acre-feet. Based on current data and an estimated rate of compaction of deposited sediment, the assumption of no appreciable change in hydrologic conditions in the drainage area, the leading edge of the principal delta will reach the irrigation outlet in 40-45 years. It is recommended that a resurvey of sediment range lines be made during the period 1973-75.

  17. Modeling In situ sediment oxygen demand in the Arroyo Colorado

    E-print Network

    Kasprzak, Kevin Ray

    2001-01-01

    and are targeted for rehabilitation under the Total Maximum Daily Load (TMDL) program. In some rivers, sediment oxygen demand (SOD) accounts for as much as 50% of the total oxygen depletion, making SOD a critical element in water quality modeling studies. SOD...

  18. Pollen distribution in marine surface sediments offshore Western Australia

    Microsoft Academic Search

    Sander van der Kaars; Patrick De Deckker

    2003-01-01

    We have examined the pollen content in sediments from the top of 38 cores taken offshore Western Australia (WA). Water depth for these cores ranges between 81 and 4090 m. All samples are used to plot maps of total pollen and total Pteridophyta spore concentration. Only the 26 core tops that yielded sufficient pollen grains (>35) are used in the

  19. 2001 Annual Energy Review

    NSDL National Science Digital Library

    The US Department of Energy's Energy Information Administration (EIA) describes itself as providing policy-independent data, forecasts, and analyses to promote sound policy making, efficient markets, and public understanding regarding energy and its interaction with the economy and the environment. The EIA Web site provides many informational pages and publications including the newly released 2001 Annual Energy Review. The report covers fossil fuels, nuclear electricity, renewable energy, and total energy by key activity -- all of which can be viewed online or downloaded. One handy feature of the site is the What's New link that contains all of the most important content changes that took place in this year's report.

  20. Sediment cascade modelling for stochastic torrential sediment transfers forecasting in a changing alpine climate

    NASA Astrophysics Data System (ADS)

    Rudaz, Benjamin; Bardou, Eric; Jaboyedoff, Michel

    2015-04-01

    Alpine ephemeral streams act as links between high altitude erosional processes, slope movements and valley-floor fluvial systems or fan storage. Anticipating future mass wasting from these systems is crucial for hazard mitigation measures. Torrential activity is highly stochastic, with punctual transfers separating long periods of calm, during which the system evolves internally and recharges. Changes can originate from diffuse (rock faces, sheet erosion of bared moraines), concentrated external sources (rock glacier front, slope instabilities) or internal transfers (bed incision or aggradation). The proposed sediment cascade model takes into account those different processes and calculates sediment transfer from the slope to the channel reaches, and then propagates sediments downstream. The two controlling parameters are precipitation series (generated from existing rain gauge data using Gumbel and Extreme Probability Distribution functions) and temperature (generated from local meteorological stations data and IPCC scenarios). Snow accumulation and melting, and thus runoff can then be determined for each subsystem, to account for different altitudes and expositions. External stocks and sediment sources have each a specific response to temperature and precipitation. For instance, production from rock faces is dependent on frost-thaw cycles, in addition to precipitations. On the other hand, landslide velocity, and thus sediment production is linked to precipitations over longer periods of time. Finally, rock glaciers react to long-term temperature trends, but are also prone to sudden release of material during extreme rain events. All those modules feed the main sediment cascade model, constructed around homogeneous torrent reaches, to and from which sediments are transported by debris flows and bedload transport events. These events are determined using a runoff/erosion curve, with a threshold determining the occurrence of debris flows in the system. If a debris flow is triggered, it propagates downstream and changes volume, depending on direction shift (lateral deposits), changes in bed slope (deposition or erosion) and debris flow volume (bulking). The model is applied to various torrential systems on which the model can be calibrated. The random sequence of precipitation events, annual variations in temperature, climate change affecting temperatures and/or precipitation produce a general trend in sediment production for a given torrential system. The results and sensibility analysis showcase the importance of mass wasting processes above streams, as well as the crucial role of rain-melt events in the spring and summer for alpine streams. The model correctly reproduces observed threshold behaviour of the stream system by external forcing, and stock exhaustion following an increase in extreme precipitation events. The model results, especially the size/frequency distribution of debris flow volumes are crucial to maintain mitigation measures such as retention dams, and give clues for future sediment cascade modelling.

  1. Characterizing toxicity of metal-contaminated sediments from mining areas

    USGS Publications Warehouse

    Besser, John M.; Brumbaugh, William G.; Ingersoll, Christopher G.

    2015-01-01

    This paper reviews methods for testing the toxicity of metals associated with freshwater sediments, linking toxic effects with metal exposure and bioavailability, and developing sediment quality guidelines. The most broadly applicable approach for characterizing metal toxicity is whole-sediment toxicity testing, which attempts to simulate natural exposure conditions in the laboratory. Standard methods for whole-sediment testing can be adapted to test a wide variety of taxa. Chronic sediment tests that characterize effects on multiple endpoints (e.g., survival, growth, and reproduction) can be highly sensitive indicators of adverse effects on resident invertebrate taxa. Methods for testing of aqueous phases (pore water, overlying water, or elutriates) are used less frequently. Analysis of sediment toxicity data focuses on statistical comparisons between responses in sediments from the study area and responses in one or more uncontaminated reference sediments. For large or complex study areas, a greater number of reference sediments is recommended to reliably define the normal range of responses in uncontaminated sediments – the ‘reference envelope’. Data on metal concentrations and effects on test organisms across a gradient of contamination may allow development of concentration-response models, which estimate metal concentrations associated with specified levels of toxic effects (e.g. 20% effect concentration or EC20). Comparisons of toxic effects in laboratory tests with measures of impacts on resident benthic invertebrate communities can help document causal relationships between metal contamination and biological effects. Total or total-recoverable metal concentrations in sediments are the most common measure of metal contamination in sediments, but metal concentrations in labile sediment fractions (e.g., determined as part of selective sediment extraction protocols) may better represent metal bioavailability. Metals released by the weak-acid extraction of acid-volatile sulfide (AVS), termed simultaneously-extracted metals (SEM), are widely used to estimate the ‘potentially-bioavailable’ fraction of metals that is not bound to sulfides (i.e., SEM-AVS). Metal concentrations in pore water are widely considered to be direct measures of metal bioavailability, and predictions of toxicity based on pore-water metal concentrations may be further improved by modeling interactions of metals with other pore-water constituents using Biotic Ligand Models. Data from sediment toxicity tests and metal analyses has provided the basis for development of sediment quality guidelines, which estimate thresholds for toxicity of metals in sediments. Empirical guidelines such as Probable Effects Concentrations or (PECs) are based on associations between sediment metal concentrations and occurrence of toxic effects in large datasets. PECs do not model bioavailable metals, but they can be used to estimate the toxicity of metal mixtures using by calculation of probable effect quotients (PEQ = sediment metal concentration/PEC). In contrast, mechanistic guidelines, such as Equilibrium Partitioning Sediment Benchmarks (ESBs) attempt to predict both bioavailability and mixture toxicity. Application of these simple bioavailability models requires more extensive chemical characterization of sediments or pore water, compared to empirical guidelines, but may provide more reliable estimates of metal toxicity across a wide range of sediment types.

  2. The effects of sieving and spatial variability of estuarine sediment toxicity samples on sediment chemistry.

    PubMed

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

    2004-11-01

    In 1998, we conducted a field-validation study of the chronic 28-day whole-sediment toxicity test with Leptocheirus plumulosus in Baltimore Harbor, MD, an area where this amphipod is indigenous. This study included an evaluation of the effect of sieving on sediment chemical concentrations and the use of field replicates, or separate grabs from the same site, which provided an estimation of within-site chemical and toxicologic variability. Six stations in Baltimore Harbor, MD, were included in this evaluation. Chemical analysis of two separate unsieved field replicates from the six sites indicated that, overall, the chemical concentrations of replicates within each site were similar, especially for metals. Organic contaminants particularly total PCBs, had the highest variability between replicates. Chemical variability did not appear to be related to differences in organic carbon content or grain size or to variability in toxicologic end points. Results supported the use of composite samples in sediment toxicity tests. In addition, in most cases, sieving had little effect on sediment chemistry. For the metals and trace elements, only selenium showed a substantial change after sieving, with some samples increasing after sieving and others decreasing. Concentrations of acid-volatile sulfide (AVS) increased 194.6% at one station after sieving, although in most other cases, AVS and simultaneously extracted metals remained relatively unchanged. As expected, concentrations of organics generally decreased after sieving, but in the majority of cases this decrease was small (i.e., coefficient of variation < or = 25%). Total benzene hexachloride and total chlordanes had the greatest changes, whereas polychlorinated biphenyl concentrations decreased at only two stations after sieving. Concentrations of polyaromatic hydrocarbons showed little change after sieving. These changes in sediment chemistry due to sieving must be viewed in the larger context of the potentially confounding effects that indigenous organisms may have on the interpretation of test results from whole-sediment toxicity tests. PMID:15499494

  3. Comprehensive Characteristics of Bottom Sediments of Water Bodies of Various Types in the Kiliya Delta of the Danube River

    EPA Science Inventory

    The "triad" approach, including analysis of the total content of toxicants, bioassay of bottom sediments, and the study of the structure of zoo- and phytobenthos communities, was used in assessing the quality of bottom sediments. It has been found that the studied bottom sediment...

  4. Episodic sediment delivery and landscape connectivity in the Mancos Shale badlands and Fremont River system, Utah, USA

    Microsoft Academic Search

    Andrew E. Godfrey; Benjamin L. Everitt; José F. Martín Duque

    2008-01-01

    The Fremont River drains about 1000 km2 of Mancos Shale badlands, which provide a large percentage of the total sediment load of its middle and lower reaches. Factors controlling sediment movement include: weathering that produces thin paralithic soils, mass movement events that move the soil onto locations susceptible to fluvial transport, intense precipitation events that move the sediment along rills and

  5. Urban rivers as conveyors of hydrocarbons to sediments of estuarine areas: source characterization, flow rates and mass accumulation.

    PubMed

    Mauad, Cristiane R; Wagener, Angela de L R; Massone, Carlos G; Aniceto, Mayara da S; Lazzari, Letícia; Carreira, Renato S; Farias, Cássia de O

    2015-02-15

    Aliphatic (n-C12-n-C40, unresolved complex mixture, resolved peaks) and aromatic hydrocarbons (46 PAH) were investigated in suspended particulate matter (SPM) sampled over eleven months in six of the major rivers and two channels of the Guanabara Bay Basin. PAH flow rates of the most contaminated rivers, the contribution to the PAH sediment load of the receiving bay, and the main sources of hydrocarbons were determined. PAH (38) ranged from 28 ng L(-1) to 11,514 ng L(-1). Hydrocarbon typology and statistical evaluation demonstrated contribution of distinct sources in different regions and allowed quantification of these contributions. Total flow rate for the five major rivers amounts to 3 t year(-1) and responds for 30% of the total PAH annual input into the northern area of the Guanabara Bay. For the first time PAH mass deposited in the bay sediments has been estimated and shall serve as base for decision making and source abatement. PMID:25434473

  6. 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 (?W = WR (downstream) - WR (upstream) < 0). Downstream of Orkhon river (below confluence with Tuul) ?W = - 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 suspended and dissolved matter transport is indicated along Tuul-Orkhon river system (right tributary of the Selenga river where Mongolia capital Ulaanbaator, gold mine Zaamar and few other mines). The results provide evidence on a connection between increased heavy metal concentrations in water-sediment systems of transboundary rivers and pollutant source zones at industrial and mining centers, both as in-channel erosion and land use.

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

    PubMed

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

    2013-11-01

    This study evaluated the chronic toxicity of Ni-spiked freshwater sediments to benthic invertebrates. A 2-step spiking procedure (spiking and sediment dilution) and a 2-stage equilibration period (10?wk anaerobic and 1?wk aerobic) were used to spike 8 freshwater sediments with wide ranges of acid-volatile sulfide (AVS; 0.94-38?µmol/g) and total organic carbon (TOC; 0.42-10%). Chronic sediment toxicity tests were conducted with 8 invertebrates (Hyalella azteca, Gammarus pseudolimnaeus, Chironomus riparius, Chironomus dilutus, Hexagenia sp., Lumbriculus variegatus, Tubifex tubifex, and Lampsilis siliquoidea) in 2 spiked sediments. Nickel toxicity thresholds estimated from species-sensitivity distributions were 97?µg/g and 752?µg/g (total recoverable Ni; dry wt basis) for sediments with low and high concentrations of AVS and TOC, respectively. Sensitive species were tested with 6 additional sediments. The 20% effect concentrations (EC20s) for Hyalella and Gammarus, but not Hexagenia, were consistent with US Environmental Protection Agency benchmarks based on Ni in porewater and in simultaneously extracted metals (SEM) normalized to AVS and TOC. For Hexagenia, sediment EC20s increased at less than an equimolar basis with increased AVS, and toxicity occurred in several sediments with Ni concentrations in SEM less than AVS. The authors hypothesize that circulation of oxygenated water by Hexagenia led to oxidation of AVS in burrows, creating microenvironments with high Ni exposure. Despite these unexpected results, a strong relationship between Hexagenia EC20s and AVS could provide a basis for conservative site-specific sediment quality guidelines for Ni. PMID:23657897

  8. Holocene and recent sediment accumulation rates in Southern Lake Michigan

    NASA Astrophysics Data System (ADS)

    Colman, S. M.; King, J. W.; Jones, G. A.; Reynolds, R. L.; Bothner, M. H.

    2000-11-01

    Rates of sediment accumulation in Lake Michigan are a key component of its geologic history and provide important data related to societal concerns such as shoreline erosion and the fate of anthropogenic pollutants. Previous attempts to reconstruct Holocene rates of sediment accumulation in Lake Michigan, as well as in the other Laurentian Great Lakes, have been bedeviled by the effect of refractory terrestrial material on radiocarbon ages from total organic carbon samples of lake sediments. AMS radiocarbon ages on small samples of biogenic carbonate (ostracodes and mollusks) in Lake Michigan provide accurate Holocene ages. The present bicarbonate reservoir effect is estimated from shells of mollusks collected live before atmospheric nuclear testing to be 250 yr. From paired samples of biogenic carbonate and terrestrial macrofossils, the past reservoir effect is thought to be less than 500 yr. The radiocarbon ages indicate a distinct decrease in sediment accumulation rates throughout the southern basin of Lake Michigan at about 5 ka, about the time when lake level stabilized at the Nipissing level after rising rapidly for several thousand years. Average rates of sediment accumulation for the historic period (the last 150 yr) can be estimated from radioisotopes ( 210Pb and 137Cs), pollen stratigraphy, and changes in sediment properties associated with human activity. Multiple methods are necessary because at any given site, problems arise in the assumptions or applicability of one or more methods. In general, the mass accumulation calculations suggest that sediments were deposited 4 to 11 times faster in the historic period than before human settlement. The character of the sediment did not change in a dramatic way, but sediment magnetic properties suggest shifts in the sources of sediment. The data suggest that some of the changes in sources and (or) character of the sediment occurred just before human settlement and were probably related to climatic changes associated with the Little Ice Age.

  9. Dark Carbon Fixation: An Important Process in Lake Sediments

    PubMed Central

    Santoro, Ana Lúcia; Bastviken, David; Gudasz, Cristian; Tranvik, Lars; Enrich-Prast, Alex

    2013-01-01

    Close to redox boundaries, dark carbon fixation by chemoautotrophic bacteria may be a large contributor to overall carbon fixation. Still, little is known about the relative importance of this process in lake systems, in spite the potentially high chemoautotrophic potential of lake sediments. We compared rates of dark carbon fixation, bacterial production and oxygen consumption in sediments from four Swedish boreal and seven tropical Brazilian lakes. Rates were highly variable and dark carbon fixation amounted up to 80% of the total heterotrophic bacterial production. The results indicate that non-photosynthetic carbon fixation can represent a substantial contribution to bacterial biomass production, especially in sediments with low organic matter content. PMID:23776549

  10. Influence of primary sedimentation on pre-denitrification system performances.

    PubMed

    Esposito, G; Bastianutti, C; Bortone, G; Pirozzi, F; Sgroi, S

    2001-01-01

    The effects of suppressing primary sedimentation on nitrogen removal efficiency of a pre-denitrification system have been evaluated for a large municipal wastewater treatment plant. Simulations have been carried out using the STOAT model. For both the process schemes with and without primary sedimentation, nitrification efficiencies are calculated for increasing influent loads of COD, total N and suspended solids. The sensitivity analysis shows that for the usual carbon to nitrogen ratios in the raw influent both the process schemes allow the requested removal efficiencies, whereas for significantly high C/N ratios the scheme with primary sedimentation is preferable. PMID:11496661

  11. Phosphorus cycling in sediments of the Bohai and Yellow Seas

    Microsoft Academic Search

    Su Mei Liu; Jing Zhang; Dao Ji Li

    2004-01-01

    Using a box-sampler, surface and core sediment samples were collected from the Bohai and Yellow Seas in 1998–1999. The sediments were sequentially extracted to determine six phosphorus fractions, and non-sequentially extracted for total P (TP) and inorganic P (IP), where the difference between TP and IP was assumed to be organic P (OP). It was found that more than 70%

  12. Evaluation of sedimentation coefficients in self-associating systems

    E-print Network

    Weirich, Charlotte Elaine

    1972-01-01

    for self-associating systems are apparent weight average sedimentation coefficients (s a) which are concentration dependent. The expression, over a small concentration range, for the values of the sedimentation coefficients for monomer (sl) and dimer (s...&) in a monomer-dimer self-associating system is given by: s )+8 BKci (1+Key)(1+gc) Where K is the equilibrium constant, c& is the concentration of the monomer, g, the hydrodynamic concentration dependence parame- ter, and c is the total solute...

  13. Behaviour of anthropogenic mercury in coastal marine sediments

    Microsoft Academic Search

    Christian Gagnon; Émilien Pelletier; Alfonso Mucci

    1997-01-01

    The diagenetic behaviour of anthropogenic mercury accumulated in sediments of the Saguenay Fjord (Canada) was investigated. Box-cores taken along its main axis and in the St. Lawrence estuary were analyzed for bulk sediment and porewater total and methyl-mercury concentrations as well as a number of other chemical variables. Mercury concentrations as high as 10,000 ng g?1 (dry weight) were measured

  14. Methane cycling in the sediments of Lake Washington

    USGS Publications Warehouse

    Kuivila, K.M.; Murray, J.W.; Devol, A.H.; Lidstrom, M.E.; Reimers, C.E.

    1988-01-01

    About half of the methane flux from depth is oxidized to CO2 in the upper 0.7 cm of the sediments and the remainder escapes into the water column. In terms of the total carbon budget of the lake, the upward flux of methane is insignificant with only about 2% of the carbon fixed by primary production being returned as methane. The upward flux of methane, however, does represent about 20% of the organic carbon decomposed within the sediments. -from Authors

  15. Recolonization of macrozoobenthos on defaunated sediments in a hypertrophic brackish lagoon: effects of sulfide removal and sediment grain size.

    PubMed

    Kanaya, Gen

    2014-04-01

    Influences of sediment types on recolonization of estuarine macrozoobenthos were tested using enclosures in a hypertrophic lagoon. Three types of azoic sediment, sand (S), sulfide-rich mud (M), and mud removed of sulfide through iron addition (MFe), were set in field for 35 days during a hypoxic period. A total of 14 taxa including opportunistic polychaetes and amphipods occurred. Infaunal community in S treatment was characterized by highest diversity, total density and biomass, and population density of five dominant taxa, while those parameters were lowest in M treatment. Sulfide removal in MFe treatment achieved much higher density, biomass, and population densities of several taxa in the sediment. Multivariate analyses demonstrated that the established community structure was unique to each treatment. These imply that dissolved sulfide level as well as sediment grain size is a key determinant for the community composition and recolonization speed of early colonists in estuarine soft-bottom habitats. PMID:24447433

  16. Skiff-based Sonar/LiDAR Survey to Calibrate Reservoir Volumes for Watershed Sediment Yield Studies: Carmel River Example

    NASA Astrophysics Data System (ADS)

    Smith, D. P.; Kvitek, R.; Quan, S.; Iampietro, P.; Paddock, E.; Richmond, S. F.; Gomez, K.; Aiello, I. W.; Consulo, P.

    2009-12-01

    Models of watershed sediment yield are complicated by spatial and temporal variability of geologic substrate, land cover, and precipitation parameters. Episodic events such as ENSO cycles and severe wildfire are frequent enough to matter in the long-term average yield, and they can produce short-lived, extreme geomorphic responses. The sediment yield from extreme events is difficult to accurately capture because of the obvious dangers associated with field measurements during flood conditions, but it is critical to include extreme values for developing realistic models of rainfall-sediment yield relations, and for calculating long term average denudation rates. Dammed rivers provide a time-honored natural laboratory for quantifying average annual sediment yield and extreme-event sediment yield. While lead-line surveys of the past provided crude estimates of reservoir sediment trapping, recent advances in geospatial technology now provide unprecedented opportunities to improve volume change measurements. High-precision digital elevation models surveyed on an annual basis, or before-and-after specific rainfall-runoff events can be used to quantify relations between rainfall and sediment yield as a function of landscape parameters, including spatially explicit fire intensity. The Basin-Complex Fire of June and July 2008 resulted in moderate to severe burns in the 114 km^2 portion of the Carmel River watershed above Los Padres Dam. The US Geological Survey produced a debris flow probability/volume model for the region indicating that the reservoir could lose considerable capacity if intense enough precipitation occurred in the 2009-10 winter. Loss of Los Padres reservoir capacity has implications for endangered steelhead and red-legged frogs, and groundwater on municipal water supply. In anticipation of potentially catastrophic erosion, we produced an accurate volume calculation of the Los Padres reservoir in fall 2009, and locally monitored hillslope and fluvial processes during winter months. The pre-runoff reservoir volume was developed by collecting and merging sonar and LiDAR data from a small research skiff equipped with a high-precision positioning and attitude-correcting system. The terrestrial LiDAR data were augmented with shore-based total station positioning. Watershed monitoring included benchmarked serial stream surveys and semi-quantitative assessment of a variety of near-channel colluvial processes. Rainfall in the 2009-10 water year was not intense enough to trigger widespread debris flows of slope failure in the burned watershed, but dry ravel was apparently accelerated. The geomorphic analysis showed that sediment yield was not significantly higher during this low-rainfall year, despite the wide-spread presence of very steep, fire-impacted slopes. Because there was little to no increase in sediment yield this year, we have postponed our second reservoir survey. A predicted ENSO event that might bring very intense rains to the watershed is currently predicted for winter 2009-10.

  17. Preferential flow and segregation of porewater solutes in Wetland sediment

    USGS Publications Warehouse

    Harvey, J.W.; Chambers, R.M.; Hoelscher, J.R.

    1995-01-01

    Sediment macropores (with effective diameters larger than 100 ??m) comprise 11% of the bulk sediment volume in a tidal freshwater wetland vegetated with Peltandra virginica. In order to determine effects of macroporous sediment structure on solute transport, we conducted a solute tracer experiment in the sediment. The effective transport volume (??eff, the volume of sediment through which solute was transported normalized to sediment bulk volume) was 0.15 cm3 cm-3, which is considerably smaller than the total pore space that is potentially available for transport (porosity of sediment is 0.63 cm3 cm-3). A mean transport time of 13 d was required to flush preferential flow paths in Peltandra hummocks; hydrologic turnover of the volumetrically dominant matrix pores (0.53 cm3 cm-3) was apparently much slower. Based on porewater sampler design and hydrological principles, we suggest that N2-purged tension solution samplers and diffusion equilibrators preferentially sample porewater from macropore and matrix domains, respectively. Dissolved ammonium and orthophosphate concentrations were three-fold higher in matrix pores compared to macropores, which is consistent with our finding that more rapid hydrological flushing occurred in macropores compared to matrix pores. Further evaluation of porewater sampler designs in macroporous sediment is needed to improve studies of hydrologic transport and biogeochemical cycling in wetlands. ?? 1995 Estuarine Research Federation.

  18. Volatilization of extensively dechlorinated polychlorinated biphenyls from historically contaminated sediments

    SciTech Connect

    Bushart, S.P.; Bush, B.; Barnard, E.L.; Bott, A. [State Univ. of New York, NY (United States). School of Public Health]|[New York State Dept. of Health, Albany, NY (United States)

    1998-10-01

    A study was conducted as a preliminary characterization of the ability of polychlorinated biphenyl (PCB)-contaminated sediments to volatilize PCBs into the air upon drying under conditions meant to be environmentally relevant. Sediments collected from the St. Lawrence River contained high levels of PCBs. The PCB contamination consisted of high levels of mainly ortho-substituted mono- and dichlorobiphenyls, suggesting that the original contamination had been transformed by microbial reductive dechlorination. These sediments lost 0.07 to 1.7% of their total PCB content to the air during a 24-h drying cycle. Sediments with varying amounts of overlying water lost significantly less PCB to the air within the first few cycles than native sediments with no overlying water. Losses due to PCB volatilization were well correlated to sediment PCB concentration and water loss but not to drying temperatures (4--43 C) within 24-h drying cycles. The PCB congeners representing >90% of those volatilized within the first 24 h of drying were those produced in the sediment samples as a result of microbial reductive dechlorination of the original PCB contamination. The presence of these congeners in volatilized air samples was positively confirmed by gas chromatography-mass spectrometry with Fourier transform infrared detection (FTIR). These results strongly suggest that significant amounts of mono-, di-, and trichlorobiphenyls may be volatilized from PCB-contaminated sediments at ambient environmental conditions and that this PCB volatilization may be enhanced by microbial reductive dechlorination.

  19. Hazelwood Interim Storage Site: Annual site environment report, Calendar year 1985

    SciTech Connect

    Not Available

    1986-11-01

    The Hazelwood Interim Storage Site (HISS) is presently used for the storage of low-level radioactively contaminated soils. Monitoring results show that the HISS is in compliance with DOE Derived Concentration Guides (DCGs) and radiation protection standards. During 1985, annual average radon concentrations ranged from 10 to 23% of the DCG. The highest external dose rate at the HISS was 287 mrem/yr. The measured background dose rate for the HISS area is 99 mrem/yr. The highest average annual concentration of uranium in surface water monitored in the vicinity of the HISS was 0.7% of the DOE DCG; for /sup 226/Ra it was 0.3% of the applicable DCG, and for /sup 230/Th it was 1.7%. In groundwater, the highest annual average concentration of uranium was 12% of the DCG; for /sup 226/Ra it was 3.6% of the applicable DCG, and for /sup 230/Th it was 1.8%. While there are no concentration guides for stream sediments, the highest concentration of total uranium was 19 pCi/g, the highest concentration of /sup 226/Ra was 4 pCi/g, and the highest concentration of /sup 230/Th was 300 pCi/g. Radon concentrations, external gamma dose rates, and radionuclide concentrations in groundwater at the site were lower than those measured in 1984; radionuclide concentrations in surface water were roughly equivalent to 1984 levels. For sediments, a meaningful comparison with 1984 concentrations cannot be made since samples were obtained at only two locations and were only analyzed for /sup 230/Th. The calculated radiation dose to the maximally exposed individual at the HISS, considering several exposure pathways, was 5.4 mrem, which is 5% of the radiation protection standard.

  20. Trends in suspended-sediment loads and concentrations in the Mississippi River Basin, 1950–2009

    USGS Publications Warehouse

    Heimann, David C.; Sprague, Lori A.; Blevins, Dale W.

    2011-01-01

    Trends in loads and concentrations of suspended sediment and suspended sand generally were downward for stations within the Mississippi River Basin during the 60-, 34-, and 12-year periods analyzed. Sediment transport in the lower Mississippi River has historically been, and continues to be, most closely correlative to sediment contributions from the Missouri River, which generally carried the largest annual suspended-sediment load of the major Mississippi River subbasins. The closure of Fort Randall Dam in the upper Missouri River in 1952 was the single largest event in the recorded historical decline of suspended-sediment loads in the Mississippi River Basin. Impoundments on tributaries and sediment reductions as a result of implementation of agricultural conservation practices throughout the basin likely account for much of the remaining Mississippi River sediment transport decline. Scour of the main-stem channel downstream from the upper Missouri River impoundments is likely the largest source of suspended sand in the lower Missouri River. The Ohio River was second to the Missouri River in terms of sediment contributions, followed by the upper Mississippi and Arkansas Rivers. Declines in sediment loads and concentrations continued through the most recent analysis period (1998–2009) at available Mississippi River Basin stations. Analyses of flow-adjusted concentrations of suspended sediment indicate the recent downward temporal changes generally can be explained by corresponding decreases in streamflows.

  1. Sediment modification by seagrass beds: Muddification and sandification induced by plant cover and environmental conditions

    NASA Astrophysics Data System (ADS)

    van Katwijk, M. M.; Bos, A. R.; Hermus, D. C. R.; Suykerbuyk, W.

    2010-09-01

    Seagrasses are well-known ecosystem engineers. They reduce water dynamics and sediment resuspension, and trap fine sediments. However, exceptions of this paradigm have been reported. To test whether these exceptions could be related to plant cover and environmental conditions, we investigated sediment modification under influence of seagrass presence in various annual eelgrass ( Zostera marina) beds with varying plant cover and sediment composition. At the relatively wave-exposed, sandy sites, dense vegetation caused muddification (increase in fine sediments and organic content) of the sediments. Sparse vegetation (<35% cover) had no effect, as such confirming the classical sediment trapping paradigm. In contrast, at the sheltered sites with muddy sediments, dense vegetation had no effect on the sediment composition, and in sparse vegetation sandification (decrease in fine sediments and organic content) was recorded. Sandification was never recorded before and was probably related to turbulence enhancement. Both, muddification and sandification are likely to provide a feedback on seagrass performance. Muddification may increase the nutrient input and, depending on the nutrient status of the system, either stimulate or reduce seagrass development. Similarly, sandification may postpone and even prevent extinction of seagrass beds when it occurs in areas that may have become too muddy for seagrass growth.

  2. 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.

  3. 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.

  4. Sediment contamination and associates laboratory-measured bioaccumulation in New York/New Jersey waterways

    SciTech Connect

    Rosman, L.B. [Army Corps of Engineers, New York, NY (United States); Barrows, E.S. [Battelle/Marine Sciences Lab., Sequim, WA (United States)

    1995-12-31

    Sediments from 10 New York/New Jersey waterways within the Hudson-Raritan Estuary and Long Island Sound were collected to depths representative of dredging activity. Composited core sediments representing each waterway were analyzed for metals, PAHs, PCBs, and pesticides. To assess bioaccumulation, sand worms (Nereis virens) and blunt-nose clams (Macoma nasuta) were exposed for 28 days to sediment composites and to New York Bight sediment. Tissues were analyzed for the same constituents as the sediment samples. The results highlight the range and magnitude of sediment contamination in NY/NJ waterways. Concentrations of some metals in sediments, compared with NY Bight sediment, were at least 10 times higher. Total PAHs reached 30,000 {micro}g/kg (dry weight). The sum of DDT, DDD, and DDE, the dominant pesticides, exceeded 3,000{micro}g/kg (dry weight). Total PCBs approached 3,000 {micro}g/kg (dry weight). Tissues exposed to sediments from several waterways bioaccumulated organic compounds at concentrations 10 times greater than those exposed to New York Bight sediments. Metals were bioaccumulated to a lesser degree. The presence and extent of bioaccumulated contaminants, along with sediment chemistry and benthic toxicity, create a profile characterizing each waterway.

  5. Effect of Elodea nuttallii roots on bacterial communities and MMHg proportion in a Hg polluted sediment.

    PubMed

    Regier, Nicole; Frey, Beat; Converse, Brandon; Roden, Eric; Grosse-Honebrink, Alexander; Bravo, Andrea Garcia; Cosio, Claudia

    2012-01-01

    The objective of this study was to assess the effect of a rooted macrophyte Elodea nuttallii on rhizosphere bacterial communities in Hg contaminated sediments. Specimens of E. nuttallii were exposed to sediments from the Hg contaminated Babeni reservoir (Olt River, Romania) in our microcosm. Plants were allowed to grow for two months until they occupied the entirety of the sediments. Total Hg and MMHg were analysed in sediments where an increased MMHg percentage of the total Hg in pore water of rhizosphere sediments was found. E. nuttallii roots also significantly changed the bacterial community structure in rhizosphere sediments compared to bulk sediments. Deltaproteobacteria dominated the rhizosphere bacterial community where members of Geobacteraceae within the Desulfuromonadales and Desulfobacteraceae were identified. Two bacterial operational taxonomic units (OTUs) which were phylogenetically related to sulfate-reducing bacteria (SRB) became abundant in the rhizosphere. We suggest that these phylotypes could be potentially methylating bacteria and might be responsible for the higher MMHg percentage of the total Hg in rhizosphere sediments. However, SRB were not significantly favoured in rhizosphere sediments as shown by qPCR. Our findings support the hypothesis that rooted macrophytes created a microenvironment favorable for Hg methylation. The presence of E. nuttallii in Hg contaminated sediments should therefore not be overlooked. PMID:23029102

  6. Effect of Elodea nuttallii Roots on Bacterial Communities and MMHg Proportion in a Hg Polluted Sediment

    PubMed Central

    Regier, Nicole; Frey, Beat; Converse, Brandon; Roden, Eric; Grosse-Honebrink, Alexander; Bravo, Andrea Garcia; Cosio, Claudia

    2012-01-01

    The objective of this study was to assess the effect of a rooted macrophyte Elodea nuttallii on rhizosphere bacterial communities in Hg contaminated sediments. Specimens of E. nuttallii were exposed to sediments from the Hg contaminated Babeni reservoir (Olt River, Romania) in our microcosm. Plants were allowed to grow for two months until they occupied the entirety of the sediments. Total Hg and MMHg were analysed in sediments where an increased MMHg percentage of the total Hg in pore water of rhizosphere sediments was found. E. nuttallii roots also significantly changed the bacterial community structure in rhizosphere sediments compared to bulk sediments. Deltaproteobacteria dominated the rhizosphere bacterial community where members of Geobacteraceae within the Desulfuromonadales and Desulfobacteraceae were identified. Two bacterial operational taxonomic units (OTUs) which were phylogenetically related to sulfate-reducing bacteria (SRB) became abundant in the rhizosphere. We suggest that these phylotypes could be potentially methylating bacteria and might be responsible for the higher MMHg percentage of the total Hg in rhizosphere sediments. However, SRB were not significantly favoured in rhizosphere sediments as shown by qPCR. Our findings support the hypothesis that rooted macrophytes created a microenvironment favorable for Hg methylation. The presence of E. nuttallii in Hg contaminated sediments should therefore not be overlooked. PMID:23029102

  7. Environmental controls on the speciation and distribution of mercury in surface sediments of a tropical estuary, India.

    PubMed

    Chakraborty, Parthasarathi; Babu, P V Raghunadh

    2015-06-15

    Distribution and speciation of mercury (Hg) in the sediments from a tropical estuary (Godavari estuary) was influenced by the changing physico-chemical parameters of the overlying water column. The sediments from the upstream and downstream of the estuary were uncontaminated but the sediments from the middle of the estuary were contaminated by Hg. The concentrations of Hg became considerably less during the monsoon and post monsoon period. Total Hg concentrations and its speciation (at the middle of the estuary) were dependent on the salinity of the overlying water column. However, salinity had little or no effect on Hg association with organic phases in the sediments at downstream. Increasing pH of the overlying water column corresponded with an increase in the total Hg content in the sediments. Total organic carbon in the sediments played an important role in controlling Hg partitioning in the system. Uncomplexed Hg binding ligands were available in the sediments. PMID:25935803

  8. 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

  9. 9. SEDIMENTATION CHAMBER, VIEW DOWNSTREAM. AFTER SEDIMENTATION, WATER FLOWS INTO ...

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

    9. SEDIMENTATION CHAMBER, VIEW DOWNSTREAM. AFTER SEDIMENTATION, WATER FLOWS INTO ONE 8" CAST-IRON PIPELINE. - Kalaupapa Water Supply System, Waikolu Valley to Kalaupapa Settlement, Island of Molokai, Kalaupapa, Kalawao County, HI

  10. Geochemical anomalies in carbonate lacustrine sediments as seasonal and centennial environmental proxy for continental climate conditions in South Siberia during the last 2450 yrs.

    NASA Astrophysics Data System (ADS)

    Kalugin, I.; Darin, A.; Tretyakov, G.; Rogozin, D.; Khromykh, S.; Kholodova, L.; Maksimova, N.

    2012-04-01

    Sedimentation history of saline lakes efficiently reflects environmental change in catchment area especially for wet-arid conditions. Different sediment carbonates allows quantitative assessment of physicochemical conditions and bioproduction. Shira lake in South Siberia is a good representative object for detail weather-climate modeling due to it`s local hydroclimatic information and annually laminated bottom sediments. Thermodynamic estimation of rock-water multisystem in conformity with local conditions and source matter gives grounds for interpretation of measured geochemical parameters in sediments as environmental indicators like temperature, salinity, pH etc. At the same time using a modern scanning X-ray fluorescence technique for sub-millimeter microstratigraphic study of varves results quantitative environmental reconstruction year by year. Meromictic Shira Lake is closed shallow (25 m) basin 9,4x5,3 km2 of brackish water (total salinity up to 19 g/l) inflowed by small Son river. Continental climate provides mean July temperature 18o and January -20oC. A long-term waterbody stratification with intra-annual chemocline depth 11-16,2 m is observed as well as level oscillations up to 7 m Sediment has thin laminated structure, where black clay-carbonate organic bearing layers are coupled with white organic free ones. Thickness of rhythms varied from 2 mm in the uppermost 20 cm of core to 0.4 mm close to the bottom. Clastic components quartz, feldspar, micas, chlorite are distributed under dust and flood events but not regularly. Visible 6 light intervals depleted of organics are revealed along the core. They have 45-120 mm in thickness and are repeated every 200-250 mm. Dark and light sediments are different in water content as well as rock-forming element composition. LOI<500oC is rather lower in light components, that confirms lack organic matter. Correspondingly, calcite (18-30%) and monohydrocalcite (13-14%) predominate in black muds coloured by organics and hydrotroilite, but dolomite (54%), less calcite (11%) with a touch of strontianite are concentrated in light layers. To construct depth-age model 137s is measured in upper part subsampled by 5 mm. Coincidence between isotope dating and counting of individual layers corroborates annual origin of them. Then varves with average thickness 0.6 mm were counted for the complete core, and age of bottom is estimated as 2450 yrs BP. Three radiocarbon dates showed the same result on the assumption of 1200 years reservoir effect for each measurement due to input of soluble ancient carbonate from bedrocks. Computer physicochemical simulation in natural rock-water-gas multisystem of Shira lake is executed by "Selector" software used method of thermodynamic potentials minimization under local equilibrium state. Thermodynamic estimations proves that carbonate matter within annual couple is corresponded to cold (winter) conditions, and organic component - to warm season. Inverse temperature dependence for solubility product of strontianite and positive correlation between transpiration and strontianite content in solid phase both contribute to concentrate Sr in sediments during cold season due to decreasing temperature and increasing water salinity through ice cover as well. Also inverse correlation is revealed between Sr content and lake level documented from 1920 year. So light carbonate Sr-enriched layers formed during each cold season as well as at the time of extremely low lake level periods with higher saline water every 450-550 yrs. Sr signal was also measured in similar carbonate sediments of Telmen lake situated in Northern Mongolia ~800 km south-east from Shira.

  11. Climatic control of sediment yield in dry lands following climate and land cover change

    Microsoft Academic Search

    D. B. G. Collins; R. L. Bras

    2008-01-01

    Long-term climate and short-term environmental change both affect catchment sediment yield, yet isolating the respective contributions has been difficult. To help separate the different roles, a numerical ecogeomorphic model has been used to explore the erosional impacts of different environmental changes across a gradient of annual rainfall in water-limited fluvial landscapes. Results demonstrate that following vegetation disturbances, sediment yield is

  12. Concentrations and loads of suspended sediment and trace element pollutants in a small semi-arid urban tributary, San Francisco Bay, California.

    PubMed

    McKee, Lester J; Gilbreath, Alicia N

    2015-08-01

    Water-quality policy documents throughout the world often identify urban stormwater as a large and controllable impact to sensitive ecosystems, yet there is often limited data to characterize concentrations and loads especially for rare and more difficult to quantify pollutants. In response, concentrations of suspended sediments and silver, mercury and selenium including speciation, and other trace elements were measured in dry and wet weather stormwater flow from a 100 % urban watershed near San Francisco. Suspended sediment concentrations ranged between 1.4 and 2700 mg/L and varied with storm intensity. Turbidity was shown to correlate strongly with suspended sediments and most trace elements and was used as a surrogate with regression to estimate concentrations during unsampled periods and to compute loads. Mean suspended sediment yield was 31.5 t/km(2)/year. Total mercury ranged between 1.4 and 150 ng/L and was, on average, 92 % particulate, 0.9 % methylated, and 1.2 % acid labile. Total mercury yield averaged 5.7 ?g/m(2)/year. Total selenium ranged between non-detect and 2.9 ?g/L and, on average, the total load (0.027 ?g/m(2)/year) was 61 % transported in dissolved phase. Selenate (Se(VI)) was the dominant species. Silver concentrations ranged between non-detect and 0.11 ?g/L. Concentrations and loads of other trace elements were also highly variable and were generally similar to other urban systems with the exceptions of Ag and As (seldom reported) and Cr and Zn which exhibited concentrations and loads in the upper range of those reported elsewhere. Consistent with the semi-arid climatic setting, >95 % of suspended sediment, 94 % of total Hg, and 85-95 % of all other trace element loads were transported during storm flows with the exception of selenium which showed an inverse relationship between concentration and flow. Treatment of loads is made more challenging in arid climate settings due to low proportions of annual loads and greater dissolved phase during low flow conditions. This dataset fills an important local data gap for highly urban watersheds of San Francisco Bay. The field and interpretative methods, the uniqueness of the analyte list, and resulting information have general applicability for managing pollutant concentrations and loads in urban watersheds in other parts of the world and may have particularly useful application in more arid climates. PMID:26160738

  13. Early depositional history of metalliferous sediments in the Atlantis II Deep of the Red Sea: Evidence from rare earth element geochemistry

    NASA Astrophysics Data System (ADS)

    Laurila, Tea E.; Hannington, Mark D.; Petersen, Sven; Garbe-Schönberg, Dieter

    2014-02-01

    The Atlantis II Deep is a brine-filled depression on the slowly spreading Red Sea rift axis. It is by far the largest deposit of hydrothermally precipitated metals on the present ocean floor and the only known modern deposit that is analogous to laminated Fe-rich chemical sediments, such as banded iron formation (BIF). The brine pool at the bottom of the Atlantis II Deep creates an environment where most of the hydrothermally sourced elements can be dispersed and deposited over an area of ˜60 km2. We analyzed the rare earth element concentrations in 100 small-volume samples from 9 cores in different parts of the Atlantis II Deep to better understand the origins of different types of metalliferous sediments (detrital, proximal hydrothermal and distal hydrothermal). Our results agree with earlier studies based on larger bulk samples that show the composition of the major depositional units is related to major changes in the location and intensity of hydrothermal activity and the amount of hydrothermal versus background sedimentation. In this paper, we address the origins of chemically distinct laminae (down to sub-millimeter) that correspond to ˜annual deposition. REE patterns clearly reflect 3 different sources (e.g., detrital, scavenging, direct hydrothermal input). Detrital REE that are delivered to the Deep from outside account for most of the REE in the sediments of the Atlantis II Deep, similar to BIF, and are unaffected by fractionation due to hydrothermal processes during deposition and diagenesis. Fe- and Mn-(oxy)hydroxides that form at the anoxic-oxic boundary scavenge REE from the brine pool as they settle. The Fe-(oxy)hydroxides contain a larger proportion of REE from seawater than any other sediment-type and also scavenge REE from pore waters after deposition. In contrast, the Mn-(oxy)hydroxides dissolve before deposition and thus function as transporting agents between seawater and the brine. However, there is little evidence for direct seawater influence in the REE geochemistry of the sediments (e.g., Y/Ho ratio). Non-ferrous sulfides form proximal to the hydrothermal vent source and inherit an hydrothermal REE pattern. The total REE content of the presently forming Fe-(oxy)hydroxides is very low due to limited input of REE into the brine. The largest proportion of non-detrital REE appears to have been deposited early in the history of the basin from an initial brine pool that was relatively enriched in REE, followed by a change in REE chemistry in later sediments. Similar abrupt changes in the REE chemistry of ancient chemical sediments may record similar processes, including changes in local basin evolution and input of REE from different sources.

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

    NASA Astrophysics Data System (ADS)

    Lizano, Laura; Haun, Stefan

    2015-04-01

    The construction of dams and reservoirs disturb the natural morphological behavior of rivers. A natural settling effect occurs due to the reduced turbulences and flow velocities. As a consequence, reservoirs fill up with sediments which results in a reduction of storage volume, influences the operation of hydropower plants and leads in several cases to flood protection problems. The sediment depositions in reservoirs are standardly evaluated by using bathymetric data, obtained by a single beam sonar from pre-defined cross sections or by an extensive evaluation of the reservoir bed by a side scan sonar. However, a disadvantage of this method is that it is not possible to evaluate the pore water content of the depositions, which may lead as consequence to an uncertainty in the measured amount of deposited sediments. Given that a major part of sediments entering reservoirs are transported in suspension, sediment flux measurements along defined transects could give more reliable information on the settled amount of sediments and additional information on the sediment transport mechanism within the reservoir. An evaluation of the sediment fluxes is in practice often conducted by a single suspended sediment concentration (SSC) measurement in combination with a cross sectional calibration factor to take changes in the SSC along the transect into account. However, these calibration factors are often developed only for one specific in-situ condition and may give unreliable results in case that the boundaries change e.g. the hydraulic conditions. Hence an evaluation of the sediment fluxes along the whole transect would give a more reliable number for the amount of transported sediments through the reservoir. This information can afterwards be used to calculate the amount of settled sediments in different sections of the reservoir and the amount of sediments which will enter the intake. For this study the suspended sediment transport within the Peñas Blancas reservoir in Costa Rica was investigated where huge depositions have been recorded since the reservoir was built. The SSC's were measured with a LISST-SL (Laser In-Situ Scattering and Transmissometry instrument) which is based on the laser diffraction method and measures simultaneously the SSC as well as the particle size distribution. The measured SSC's were subsequently used to calculate the sediment fluxes within the transects, based on the intensity of backscattered sound from an acoustic measurement device. The total amount of deposited sediments could be calculated from the sediment fluxes, obtained by moving ADCP measurements (Acoustic Doppler Current Profiler) along chosen transects and so an image of the amount of settled sediments could be drawn. The results of this study show the advantage of using two highly sophisticated measurement devices in parallel to receive accurate numbers for sediment fluxes within reservoirs, which can in addition be used in further studies to develop management strategies to reduce sediment depositions.

  15. Sediment Deposition and Accretion in a Mid-Atlantic (U.S.A.) Tidal Freshwater Marsh

    NASA Astrophysics Data System (ADS)

    Neubauer, S. C.; Anderson, I. C.; Constantine, J. A.; Kuehl, S. A.

    2002-04-01

    Sediment deposition and accretion rates in a Virginia tidal freshwater marsh were measured to provide insight to the processes and time scales that are important for maintaining marsh surface elevation. Short-term sediment deposition rates (biweekly to monthly) measured using sediment collection tiles were spatially and temporally variable. Rates were greatest near a tidal creak and decreased along a transect extending toward the marsh interior. When integrated across the entire marsh, annual sediment deposition (as organic carbon) averaged 517±353 g C m -2 y -1 and was sufficient to balance the effects of existing relative sea level rise and marsh respiration rates. At the creekbank, the highest deposition rates were measured during summer although rates were relatively constant over time at the interior sites. Similar spatial and temporal patterns were obtained when deposition rates were calculated from 7Be inventories (monthly time scale). Sediment inventories of 7 Be were greater than those supported atmospherically, indicating that the spatial patterns of sedimentation were not due to sediment erosion and redistribution within the marsh. Accretion rates calculated from 137Cs (decadal scale) and 14 C dating (centuries to millennia) were substantially less than annual deposition rates, with a decrease in accretion rate with increasing time scale. Mineralization rates of recently deposited sediments (measured as O 2 consumption) indicated that sediment metabolism could potentially remove ˜30% of recently deposited carbon within one month of deposition. The metabolism of a labile sediment fraction could explain a portion of the observed decrease in accretion rate with increasing time scale, with the remainder due to periodic storm-induced erosion and historical variability in sediment deposition rates.

  16. Wheat Evolution: Sedimentation Testing

    NSDL National Science Digital Library

    Biotechnology and Biological Sciences Research Council

    2012-01-01

    In this activity (p.8-9 of PDF), learners investigate the evolution of wheat by conducting